Journal and Proceedings of the Royal
Society of New South Wales
ABSTRACTS OF STUDENT THESES IN
VOLS 118-132: Part 1 of 5 (VOLS 118-122)
CONTENTS
(in chronological order of publication)
1985 [v118 pts 1-2]
Fong, Joyce
Synthesis of GABA Analogues for Neurochemical Studies
The Population Structure and Reproductive Biology of Ceratonereis limnetica
Glasby, C
(Polychaeta : Nereididae) at Lower Portland, Hawkesbury River, N.S.W.
1985 [v118 pts 3-4]
Pharmacological Properties of Himbacine: An Alkaloid from Galbulimima
Gilani, S.A.
Species
1986 [v119 pts 1-2]
A Study of Hyperfid Amphipods (Peracarida: Crustacea) Associated With a
Young, Jock W.
Warm Core Eddy in the Tasman Sea
NMR Studies of the Uptake and Degradation of Peptides by Human
King, G.F.
Erythrocytes
Rodger, P.
Stochastic Theories of Solution Dynamics
Mark
Rodger, Alison Symmetry Selection Rules Analytic Development and Chemical Application
NMR Studies on the Intracellular Viscosity and Cell Volume of Human
Endre, Zoltán H.
Erythrocytes
Acute and Chronic Effects of Lead and Other Metals on GABA
Drew, Colleen A.
Neurochemistry
1987 [v119 pts 3-4]
Seow, K.T.F.P. Pancreatic Fluid and Electrolyte Secretion
Fitness Components of Chromosomal Homozygotes In Drosophila melanogaster
Pascoe, Leigh
In Age Structured Populations
Andrew Walsh Photographic Measurements of Bubble Populations from Oceanic Whitecaps
1988 [v120 pts 1-2]
[No abstracts of theses published in this issue]
1988 [v120 pts 3-4]
Pollard, G.H.
A Stochastic Analysis of Scoring Systems
Gibbons, D.S. Ultra-Violet and Tactile Pollination Guides of Some Fabaceae
1988 [v121 pts 1-2]
Studies in the Bioactivation of Chemical Carcinogens: Role of in vitro Cell
Bonin, A.M.
Mutagenesis
Chan, Hak-Kim Crystal Growth and Aerodynamics of Drug Particles
Chrisp, Jeremy
Kinetic Aspects of Calcium Metabolism in Forage Fed Sheep
Stormer
Murphy, A.B.
Observations of Alfven Waves in a Tokamak Plasma
1989 [v121 pt 3]
[No abstracts of theses published in this issue]
1989 [v121 pt 4]
Characterisation of Urban Storm Water Run-Off Quality, Jamieson Park,
McNamara, R.
N.S.W.
Palaeoecological Studies of the Ordovician Fossil Hill Limestone, Central New
Yue, Lei
South Wales
1989 [v122 pts 1-2]
Dawes, Judith,
A new Approach to Transient Electron Spin Resonance Spectroscopy
M.
Everett, David Rheological Properties of Coagulated Colloidal Suspensions
Transmembrane Chemical Shift Differences of the 31P NMR Spectra of
Kirk, Kiaran
Erythrocyte Suspensions: Origins and Applications
1990 [v122 pts 3-4]
[No abstracts of theses published in this issue]
1990-1993 [v123 pts 1-2 to v126 pts 3-4]
Go to Theses Abstracts Archive Part 2
1994-1995 [v127 pts 1-2 to v128 pts 3-4]
Go to Theses Abstracts Archive Part 3
1996-1997 [v129 pts 1-2 to v130 pts 3-4]
Go to Theses Abstracts Archive Part 4
1998-1999 [v131 pts 1-2 to v132 pts 3-4]
Go to Theses Abstracts Archive Part 5
Vol 118 parts 1-2, pp.59 [1985]
[Return to Volume’s Index]
Synthesis of GABA Analogues for Neurochemical Studies
Joyce Fong
Thesis for the Degree of Doctor of Philosophy at The University of Sydney, N.S.W., 2006.
(Department of Pharmacology)
Abstract. In my thesis, the synthesis is described of fifteen new GABA analogues. They are
from three different series, namely β-diketone derivatives, unsaturated nipecotic acid analogues,
and derivatives in the cyclopentane series. The GABA-mimetic activity of these compounds has
been assayed by measuring the inhibition of [3H]GABA binding, the potentiation of
[3H]diazepam binding, the inhibition of [3H]GABA uptake, the inhibition of GABAtransaminase activity, and the substrate-activity of GABA-transaminase in rat brain membranes,
as well as the transient contraction of the guinea-pig ileum.
The β-diketone derivatives, octahydro-1H-2-pyrindine-5,7-dione (1) and its diazo and 6-bromo
derivatives, showed negligible or very weak activity as GABA agonists with respect to inhibition
of [3H]ABA binding, uptake and transamination.
1,2,3,6-Tetrahydropyridine-3-carboxylic acid (neoguvacine) (2), the β,γ-unsaturated derivative of
the GABA uptake inhibitor nipecotic acid, has been synthesized via the dilithium salt of the N-tbutyloxycarbonyl-protected intermediate. Substitution of the intermediate with alkylating agents
or an aldehyde gave predominantly α-alkylated products as expected, but chlorination with Nchlorosuccinimide provided a route to the γ-substituted amino acids. Derivatives with bulky αand γ-substituents are less active at inhibiting GABA uptake. However, a smaller α-methyl group
and the more polar γ-hydroxyl group are better accommodated at the active site and these
derivatives retain a relatively high potency. Structure-activity studies in this series included noncyclic analogues of neoguvacine such as the β,γ-unsaturated cis, trans olefinic and acetylenic
derivatives of 5-amino-pentanoic acid. These emphasized the preference of the active site for
GABA uptake for folded conformations represented by cis-5-aminopent-3-enoic acid and
neoguvacine.
In the cyclopentane series, trans-4-aminocyclopent-2-ene carboxylic acid (3) was synthesized via
the thermal isomerization of the cis N-phthaloyl acid derivative and was resolved via crystalline
diastereomeric 2,3-isopropylidene-D-ribonolactone and D-pantolactone esters. Both optical
isomers of the β,γ-unsaturated and the saturated amino acid could be obtained from these esters.
Although the unsaturated (+)-trans-(1R,4R)-4-aminocyclopent-2-ene-1-carboxylic acid was less
active as a GABA agonist than its saturated counterpart, its potential to be converted into
tritiated radioligand was demonstrated by its reduction to the saturated amino acid without
isomerization. The conjugated (+)-(4S)-4-aminocyclopent-2-ene-1-carboxylic acid was found to
be particularly selective and potent as a GABA receptor agonist while its (-)-(4R) isomer was
conversely selective and potent at inhibiting [3HIGABA uptake into rat brain tissue.
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Vol 118 parts 1-2, pp.60 [1985]
[Return to Volume’s Index]
The Population Structure and Reproductive Biology of Ceratonereis limnetica
(Polychaeta : Nereididae) at Lower Portland, Hawkesbury River, N.S.W.
C. Glasby
Thesis for the Degree of Master of Science at the University of Sydney, N.S.W 2006, Australia.
Abstract. The reproduction and population structure of Ceratonereis linnetica occurring at Lower
Portland, a near fresh water site, was investigated over a 19 month period. The species had a
relatively short life span of 9 – 15 months. Animals spawned once, in spring and early summer,
in the benthos. There was no heteronereid metamorphosis, epitoky presumably having been
suppressed. Embryonic development was non-pelagic with larval stages brooded within the
parental tube. Very few juveniles were detected at Lower Portland, but were abundant further
downstream. It is speculated that the reproductive success of this species at Lower Portland was
poor over the study period and that individuals were recruited from further downstream. The
reproduction and life histories of other nereidids, especially fresh water species, were reviewed
and compared with Ceratonereis limnetica.
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Vol 118 parts 3-4, pp. 213-214
[1986]
[Return to Volume’s Index]
Doctoral Thesis Abstract: Pharmacological Properties of Himbacine: An Alkaloid from
Galbulimima Species
SYED ANWAR-UL HASSAN GILANI
This study was undertaken to investigate the pharmacological properties of himbacine, an
alkaloid isolated from Galbulimima species native to Australia and Papua-New Guinea. In vitro
experiments were performed on various smooth muscle and cardiac preparations as well as in vivo
experiments on anaesthetized cats.
In smooth muscle preparations, himbacine (0.1-30 μM) was found to inhibit muscarinic receptor
activation. The antagonism of acetylcholine or carbachol was competitive and a similar pA2 value
(around 7.2) was found in all smooth muscle preparations studied irrespective of whether the
tissues responded to cholinomimeties by contraction (guinea-pig ileum, trachea and oesophagus,
rat uterus and stomach) or by relaxation (rabbit aorta). When compared with atropine, himbacine
was found to be 70 - 110 times less-potent and its potency was similar to that of homatropine.
At concentrations greater than 30 μM, himbacine caused inhibition of smooth muscle
contractions induced by histamine, 5-hydroxytryptamine, Ba++ or K+ and was 6 10 times less
potent than papaverine.
In guinea-pig atria, pA2 values of himbacine for the antagonism of cholinomimetics were around
8.3 which represent at least 10 times greater potency than that found in smooth muscle
preparations. In contrast, pA2 values for atropine or homatropine in atria were similar to those
determined in smooth muscle preparations.
Gallamine, a known cardio-selective musearinic receptor antagonist was studied for comparison
and had 11 times greater affinity for cardiac muscarinic receptors than for muscarinic receptors
of ileal smooth muscle. However, antagonism of acetylcholine or carbachol, at higher
concentrations was less than expected for a competitive antagonist and exhibited nonlinear
Schild plots with slopes progressively departing from unity. The degree of antagonism of
acetylcholine was less than for carbachol at higher concentrations of gallamine.
In contrast, himbacine was a competitive antagonist over a wide range of concentrations,
exhibiting linear Schild plots with slopes not significantly different from 1. The Schild plots for
the antagonism of both acetylcholine or carbachol were similar and himbacine was
approximately 500 times more potent than gallamine.
At higher concentrations (> 1 μM), himbacine caused dose-dependent decreases in spontaneous
rate of atrial contraction, similar to the effects of quinidine and papaverine.
The effective refractory period of guinea-pig atria was prolonged by himbacine in a similar
concentration range to that causing bradycardia. The effect was qualitatively similar to that of
quinidine but himbacine was 3 times less potent.
In vivo, himbacine (1-4 mg/kg), produced dose-dependent falls in blood pressure and heart rate
in anaesthetized cats. These effects were similar in atropinised areflexic cats suggesting that no
central nervous component was involved. Himbacine at these doses was found to be devoid of
any effect on responses of cat nictitating membranes to pre-ganglionic stimulation in contrast to
hexamethonium.
It is concluded from these results that himbacine may be the prototype of a novel class of
competitive antimuscarinic agents with cardic-selectivity. Because of its selective action for
cardiac musearinic receptors, himbacine has clinical potential in the therapeutic correction of the
brady-arrhythmias currently treated by atropine.
Department of Pharmacology,
University of Sydney,
N.S.W., 2006, Australia.
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Vol 119 parts 1-2, p.135 [1986]
[Return to Volume’s Index]
Masters Thesis Abstract (University of Sydney): A Study of Hyperiid
Amphipods (Peracarida: Crustacea) Associated With a Warm Core Eddy in the
Tasman Sea
JOCK W. YOUNG
Hyperiid amphipods were sampled from in and around a warm core eddy (J) in the Tasman Sea
during three cruises between August and October, 1979. Samples were taken at night to a depth
of 400 m using a midwater trawl (RW-8). In total, 11,891 hyperiids representing 38 species and
10 families were caught, adding 13 new records for Eastern Australian waters. Synoptic
information is given for each species on taxonomy, life history data, vertical distribution,
geographic range and behavioural associations with gelatinous zooplankton. Seven species
contributed 87.1% to the total. Of these, Phrosina semilunata, Brachyacelus crusculum, Primno johnsoni,
Phronima sedentaria and Phronima atlantica were all found in significantly higher numbers outside the
eddy. Only one dominant species (Streetsia challengeri) was abundant inside the eddy and only
during August. Outside the eddy, samples were characterized by large numbers of few species
while inside, samples had a more even representation of species. Cluster analysis of species
composition and abundance showed broad groupings correlating with depth and temperature
(August), position with respect to the eddy (September, October) and the presence of salps
(September, October). It is proposed that the differences between the inside and outside hyperiid
communities are due to the response of hyperiids not only to the physical environment of the
eddy but also to their association with gelatinous zooplankton.
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Vol 119 parts 1-2, pp.137-138
[1986]
[Return to Volume’s Index]
Doctoral Thesis Abstract (University of Sydney): NMR Studies of the Uptake
and Degradation of Peptides by Human Erythrocytes
G. F. KING
The teleologically unsatisfying hypothesis that the cytosolic exopeptidases of the human
erythrocyte are merely non-functional vestiges of red-cell differentiation is critically examined.
The efficancy of 1H spin-echo NMR spectroscopy for monitoring the kinetics of exopeptidasecatalysed reactions in situ in human erythrocyte lysates and intact-cell suspensions is
demonstrated. The ability of this technique to simultaneously monitor the substrates and
products of such reactions enabled a new procedure to be developed for determining the
concentrations of reactants; this involved the calculation of unique NMR extinction coefficients
for each sample, which obviated the need for preparation of calibration curves. Furthermore, a
new, time-efficient method was developed for non-linear regression of the integrated MichaelisMenten equation, which is an implicit function of the substrate or product concentration, onto
reactant-versus-time progress curves for the purpose of obtaining steady-state kinetic parameters
for the reactions. Derivation of the sensitivity functions for the integrated Michaelis-Menten
equation revealed under what initial conditions this procedure yields the most reliable parameter
estimates.
Since peptides are not products of normal erythrocyte metabolism, the work presented in the
thesis examined the possibility that substrates for the cytosolic exopeptidases of these cells may
arise from extracellular sources. It is shown, for the first time, that a range of di- and tripeptides
may enter the human erythrocyte via saturable membrane transport system(s) which are
describable by simple Michaelis-Menten kinetics; all such peptides are shown to be rapidly
hydrolysed upon entering the intracellular milieu. However, preliminary evidence revealed that
the rate of peptide uptake by human erythrocytes declines markedly as the residue-number is
increased beyond three; it is consequently suggested that there may be a critical residue-number
or hydrodynamic volume which determines whether peptides are permeant to these cells.
Potential physiological roles were assigned to some of these coupled (in the kinetic sense)
peptide transport-intracellular exopeptidase systems. For example, it was demonstrated that
glutamate, which is impermeant to human erythrocytes, may be supplied to these cells via the
absorption and subsequent intracellular hydrolysis of plasma a-glutamyl-peptides. Calculations
based on the experimentally-derived steady-state kinetic parameters for the uptake and hydrolytic
processes revealed that the plasma concentration of α-glutamyl-peptides would only need to
exceed 7.3μM for this coupled system to provide enough glutamate to sustain the observed rate
of intracellular glutathione synthesis.
Figure 1: A schematic representation of the putative role of human erythrocytes, and other
tissues, in whole-body peptide turnover. The dotted line is meant to portray current uncertainty
about the exact role of human erythrocytes in the deactivation of circulating peptide hormones.
However, it was shown that human erythrocytes play only a minor role in the turnover of plasma
prolyl-peptides and that absence of erythrocyte prolidase is probably not a major factor in the
aetiology of the clinical manifestations of generalised prolidase deficiency. It was demonstrated
that the rates of cis-trans isomerisation of imidodipeptide substrates of prolidase can be
monitored using inversion-transfer NMR spectroscopy. Data obtained from such a study,
combined with progress curves obtained from 1H NMR experiments monitoring all reaction
species in the prolidase-catalysed hydrolysis of L-alanyl-L-proline, enabled the isomeric
specificity of the enzyme to be determined; it was shown that prolidase has exceptionally high, or
absolute, specificity for the trans isomer of its substrates. This information, combined with data
from the literature, enabled a new model of the active site of prolidase to be constructed.
Finally, it is proposed that human erythrocytes, by virtue of their extensive distribution, large
numbers, and peptide and amino-acid transporting capabilities, may play an important role in
whole-body peptide turnover by assimilating plasma peptides and distributing the hydrolytic
products to other tissues (see Figure 1). The clinical value of the illicit transport of otherwise
impermeant drugs into human erythrocytes by way of their peptide transport system(s) is also
discussed.
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Vol 119 parts 1-2, pp.139-140
[1986]
[Return to Volume’s Index]
Doctoral Thesis Abstract (University of Sydney): Stochastic Theories of
Solution Dynamics
P. MARK RODGER
This work undertakes an investigation into the manner in which the characteristic motion of a
molecule changes when it is immersed in a solvent (ie, solution dynamics, denoted S.D.).
Particular attention is paid to the rates of very fast (picosecond) reactions such as occurs in the
geminate recombination of iodine, or the dihedral motion of 1,1’-binaphthyl.
The results of some molecular dynamics computer simulations (M.D.) modelling a series of
monatomic and diatomic molecules in a different monatomic solvent are presented. It is found
that some simple macroscopic concepts, such as solvent viscosity and surface tension, are useful
on a molecular scale. Of particular interest to the reaction rate problem is the coefficient
describing the friction experienced by the solute molecule, ζ. From the simulations, we have
elucidated an easy-to-use three step procedure for evaluating ζ from the solvent viscosity, ϒ : (i)
an uncommon, but general form of Stokes’ law is used to calculate a value of ζ that is applicable
to the long timescale motion of spherical particles, viz. ζ°=3rϒ /(d2δρ), where δ is the solute
diameter, and δρ is the difference between the solute and solvent densities, (ii) changes in
molecular shape were found to induce changes in ζ° that were proportional to the corresponding
changes in the cross-sectional area of the solute, and (iii) a functional form for the frequency
dependence of ζ due to M.G. Sceats and D.P. Millar [to be published] was found to give a good
description of how the frequency of the solute motion modifies ζ°.
An analytic theory of S.D. that incorporates the dynamic structure of the solvent in terms of a
locally time dependent friction coefficient is developed. This theory is combined with the
computer simulations already cited to provide the basis for an extensive discussion of the
existing theories, with particular emphasis on the level of complexity required to adequately
explain the experimental observations. A rationale is thereby proposed to explain why the
simplest model (variously referred to as the Brownian motion, Langevin, Fokker-Planck, or
Kramers formalism) appears to work far better than theory suggests it should.
In the remainder of this thesis, two extensions to the Brownian theory are presented. The first of
these allows for the inclusion of long range solute-solvent interactions, which may, in principle,
be very sensitive to the conformation of the solute. A model is proposed, that leads to an
analytic expression for the rate of escape across a potential barrier under the influence of such
long range interactions; by way of example, this is applied to the problem of dihedral motion in
1,1’binaphthyl. The second extension is a procedure by which the number of degrees of freedom
in a system may be reduced by the incorporation of an effective potential energy surface. The
method is applied to the relative radial motion of diatomic molecules, as occurs, for example, in
the geminate recombination of iodine; the three dimensional problem is found to reducible to a
one dimensional problem by supplementing the intramolecular potential with a -2kTln ϒ term. It
is conjectured that this procedure is of general validity, and is not restricted to the Brownian
model; this conjecture is shown to be supported by the M.D. simulations of this work.
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Vol 119 parts 1-2, p. 141 [1986]
[Return to Volume’s Index]
Doctoral Thesis Abstract (University of Sydney): Symmetry Selection Rules
Analytic Development and Chemical Application
ALISON RODGER
This work is concerned with the development and application of symmetry selection rules for
systems with point symmetry. Relationships between point groups are developed which enable
the full structure of a point group to be expressed in terms of relationships between a limited
number of generating operations. These relationships are used in two different ways. The first
begins with the development of a group augmentation procedure, whereby a group is built up
from one of its subgroups by augmenting the subgroup with a new operation. The augmentation
procedure then enables tonsorial invariants of arbitrary order to be analytically determined for all
point groups. The Generalized Selection Rules of P.E. Schipper (GSR) (which require firstly the
determination of symmetry invariant operator products and secondly the determination of
symmetry invariant matrix elements) can now be implemented. Particular application of the GSR
is made to expressions derived for the circular dichroism (CD) of magnetic dipole allowed (mda)
transitions in systems where the transition of interest is essentially localized on an achiral
chromophore.
The theoretical analysis of mda CD proceeds by using perturbation theory to express the CD
induced into a non CD active transition by the presence of a chiral species. When the interaction
is written as a multipole expansion, the induced CD appears as a sum of terms involving
different multipole transition moments. Each term is then analysed using the GSR. The results
of this analysis are used firstly to understand experimental data to be found in the literature,
about which there has been much controversy. They are then coupled to the first systematic
experimental study of systems in which the CD results from the presence of chiral species which
(i) do not preferentially associate and (ii) do preferentially associate to the achiral chromophore.
The achiral systems studied were Coffil) metal complexes, and a range of monosaccharides were
chosen as the chiral species for (i), and tartaric acid for (ii). The metal complexes were chosen to
have a wide range of symmetries so as to comprehensively test the theoretical results which had
been developed.
The second way in which the expression of group structure in terms of relationships between
generating operations is used, is in the derivation of matrix irreducible representations (i-r’s) of
cyclic, dihedral and cubic groups. I-r’s are not available in the literature for any but the simplest
point groups despite their well-known utility for projecting out orthogonal symmetry adapted
functions. Another application for which the i-r’s are well-suited is the analysis of the symmetry
changes a system undergoes in the course of molecular vibrations or geometry changes. In this
work this is used to analyse relationships between: (i) symmetry changes and geometry changes,
and (ii) between geometry changes and the potential energy of a system; a straightforward
symmetry selection rule procedure for generating symmetry allowed reaction mechanisms (i.e.
those not precluded by symmetry) is thereby developed. Some attention is also paid to the
determining the most probable of the symmetry allowed mechanisms.
Throughout the thesis the philosophical approach taken is a two step one of firstly analytically
incorporating and fully exploiting the symmetry of the system, and secondly, where it proves
necessary, to determine details by calculation or experiment.
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Vol 119 parts 1-2, pp.143-144
[1986]
[Return to Volume’s Index]
Doctoral Thesis Abstract (University of Sydney): NMR Studies on the
Intracellular Viscosity and Cell Volume of Human Erythrocytes
ZOLTAN H. ENDRE
Viscosity estimates were made from correlation times calculated from 13C NMR measurements
of the spin-lattice relaxation time (T 1) of a constant low concentration of [α-13C]glycine in BSA
and glycerol solutions and in intact human erythrocytes. The estimates in erythrocytes were
compared with those obtained from T measurements of [glycyl-α-13C] glutathione labelled in situ
in intact erythrocytes, by utilising the glycine-exchange reaction catalysed by glutathione
synthetase. The modulation of glycine exchange was studied in order to optimise incorporation
of the 13C-labelled glycine into GSH.
Identical estimates of NMR-glycine-viscosity were obtained when either isotropic sherical [sic,
should be ‘spherical’?] rotor or prolate ellipsoidal rotor models were used to calculate probe
correlation times from the T measurements. Comparison of the estimates of NMR viscosity
obtained using [α-13C]glycine in free solution with measurements of the bulk viscosity obtained
using capillary viscometry demonstrated that: 1) with increasing solute concentration there was
progressive deviation of the estimates, and 2) different values of the NMR-glycine-viscosity were
obtained in BSA and glycerol solutions with the same bulk viscosity.
The deviation of the NMR- from the bulk viscosity values was found to result from the
progressive deviation with increasing viscosity of the measured probe correlation times froe the
theoretical values predicted for an “ideal” solution. By application of mathematical expressions
defining the concentration-dependence of the viscosity of concentrated solutions it was possible to
calculate phenomenological interaction parameters which allowed both NMR- and bulk viscosity
estimates to be defined as functions of the volume fraction of solute. These interaction
parameters were then used to quantify the relationship between bulk and NMR-glycine-viscosity
estimates phenomenologically, i.e., without the need to consider the nature of the probe-solutesolvent interaction (Figure 1). The method developed here, for calculating bulk from NMRviscosity and vice versa, is applicable to other methods of investigation where correlation times are
studied, e.g. ESR. A simple geometrical model, based on the relative sizes of probe and solute
molecules, was proposed to explain the differences between the estimates of NMR-viscosity
obtained in solutions containing different solutes but with the same bulk viscosity.
Figure 1. [α-13C]glycine correlation time as a function of normalised bulk viscosity.
Temperature, 37°C. Open circles, viscosity adjusted with BSA; solid circles, viscosity
adjusted with glycerol. The line marked “ideal” is a plot of ϒ R = 4πηro3/3kT) with ro (1.583
* 10-8 cm) determined from the solution of lowest (normalised) viscosity. The log-log plot
was used for compression of the axes. The lines fitted to the empirical data were calculated
similarly but using a theoretical function for η such that ηN = ηBΨ, where
Ψ = νN/{νB+1n(ΨB)[kB - kN]}. Thus the first equation becomes ϒ R = (4πro3kT) = ηBΨ which
allows ϒ R to be calculated in terms of the bulk viscosity using the interaction parameters νN,
νV, kN, ahd kβ which are easily estimated using non-linear least squares analysis of
normalised viscosity-Φ data.
The similarity between the estimates of NMR-viscosity, which were obtained in intact
erythroctes by using either [α-13C]glycine or [glycyl-α-13C]GSH as physiological viscosity probes,
indicated that the NMR-glycine-viscosity estimates were obtained from intra- not extracellular
glycine. Both probes yielded estimates of the NMR-viscosity of ~1.4 mPa.s at 37°C, indicating
that the restriction to motion of these small molecules in erythrocyte cytoplasm was ~1.8 times
that of isotonic saline. Estimates of NMR-glycine-viscosity in intact erythrocytes were calibrated
in situ against the intracellular haemoglobin concentration by obtaining viscosity estimates at
different cell volumes. It was then demonstrated that cell volume could be estimated from the
viscosity measurements and vice-versa. This allowed the physiological range of NMR-glycineviscosities (~1.1 to ~1.7 mPa.s) to be calculated from the physiological range of erythrocyte
volumes.
Consideration of the physiological range of NMR-glycine-viscosities indicated that: 1) increases
in intracellular viscosity resulting from observed increases in the concentration of haemoglobin
are unlikely to account for the experimentally observed decline with age in the activity of
erythrocyte superoxide dismutase, 2) these age-dependent increases in intracellular viscosity
markedly increase the calculated bulk viscosity of erythrocyte cytoplasm and that the resulting
increase in erythrocyte rididity could contribute to the splenic clearing of senescent erythrocytes
from the circulation, and 3) increases in NMR-glycine-viscosity associated with physiologically or
pathologically-induced changes in erythrocyte volume are unlikely to affect the rates of very fast
reactions unless the substrates of these reactions are present in “limiting” concentrations.
The effect of changing intracellular viscosity on the signal intensity of resonances in spectra
obtained using 1H NMR was studied by varying the volume of human erythrocytes and obtaining
spectra by using either the spin-echo or inversion-recovery spin-echo pulse sequences. In
additional studies measurements of T2 and volume magnetic susceptibility were als performed.
These studies demonstrated that marked changes in signal intensity of resonances from intraand extracellular species occurred as cell volume varied. The changes in signal intensity could not
be explained by changes in intracellular viscosity or volume magnetic susceptibility; however,
they could be accounted for by variation in the homogeneity of the magnetic field in the
erythrocyte suspensions consequent upon the-changes in erythrocyte shape which follow
alteration of erythrocyte volume. The field inhomogeneity in intra- and extracellular
compartments of erythrocytes at different cell volumes was estimated in terms of the average
field gradients in these compartments.
In other 1H NMR studies extracellular viscosity and volume susceptibility were altered. These
latter studies demonstrated that: 1) signal intensity in spin-echo spectra was a function of the
magnitude of both the viscosity and of the magnetic field gradients, 2) matching intracellular
susceptibility by adding bovine serum albumin to the extracellular compartment could enhance
the intensity of resonances in the intracellular compartment, 3) the magnitude of intracellular
field gradients in suspensions of erythrocytes at high haematocrit was determined principally by
the field gradients at the external boundary of nearby cells and not those generated within the
individual erythrocytes, and 4) the dephasing effects of the field gradients and the subsequent
echo attenuation were functions of the restriction to both rotational and translational rates of
diffusion calculated not from the value of the bulk viscosity of the solution but from that of the
NMR-viscosity experienced by the individual molecular species.
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Vol 119 parts 1-2, pp.145
[1986]
[Return to Volume’s Index]
Doctoral Thesis Abstract (University of Sydney): Acute and Chronic Effects of
Lead and Other Metals on GABA Neurochemistry
COLLEEN ANN DREW
The acute and chronic effects of lead salts on central systems related to the neurotransmitter γaminobutyric acid (GABA) have been studied (in vitro) in untreated adult rat brain and in brains
from neonatal and young adult rats following the chronic administration of lead to dams from
conception and pups from weaning. Lead was shown to affect GABA systems in vitro and to
have consistent, binding site specific effects in the chronically treated animals.
1. As divalent lead cations are readily complexed by some of the anions used to buffer
physiologcal media, the role played by the choice of buffer in variability of reported results was
investigated. The effect of load and other metal ions on the uptake, release and binding of [3H]GABA in adult rat brain was studied using buffers with varying capacity to complex divalent
ions.
Minimal effects on uptake and release were seen in solutions buffered with either phosphate or
carbonate (which complex metal cations) whereas marked effects were observed when Tris-HCl
(which does not form stable metal complexes) was used as a buffer.
The effects of lead and other metal salts on calcium-dependent, bicuculline-insensitive (GAB%)
and calcium-independent, bicuculline-sensitive (GABAA) [3H]-GABA binding to synaptic
membranes of adulut rat wholebrain were investigated us`ing Tris-citrate and Tris-HCl buffers.
As for the transport studies minimal metal effects were seen in the buffer which complexes
divalent cations (Tris-citrate), whereas marked (ion specific) effects were seen when assays were
carried out in the Tris-HCl buffer. Calcium-dependent bicuculline-insensitive/GABAB GABA
binding sites were found to be more susceptible to the effects of lead and some metal ions than
calcium-independent bicuculline-sensitive/GABAA sites.
2. The binding of [3H]-(-)-baclofen (a stereo specific agonist for the calcium-dependent,
bicuculline-insensitive/GABAb GABA binding sites), to synaptic membranes of rat cerebella was
investigated. [3H]-(-)-Baclofen showed increased specific binding, a higher affinity and lower
receptor density than equivalent studies [3H]-(±)-baclofen.
The kinetics of bicuculline-insensitive [3H]-GABA binding to cerebellar membranes and the
effects of some conformationally-restricted analogues of GABA on this and [3H]-(±)baclofen
binding indicated that folded analogues of GABA may interact with a class of GABA binding
sites insensitive to both bicuculline and (-)-baclofen.
3. The development of calcium-dependent bicuculline insensitive/GABAB (forebrain and
cerebellum and calcium-independent bicueulline-sensitive/GABAA [3H] GABA binding
(forebrain) at 10, 21 and 84 days postnatally, and the effect of chronic treatment with lead on this
development was studied in neonatal animals whose dams received either lead acetate or sodium
acetate in their drinking water from conception to weaning and normal animals given only water.
The developmental profiles of the normal animals, for both calcium-dependent bicucullineinsensitive/GABAB and calcium-independent bicuctilline-sensitive/GABAA binding of the
normal animals were similar, showing relatively constant affinity but greatly increased receptor
density from birth to 21 days postnatally.
4. Chronic lead treatment produced receptor specific effects on binding to the different sites
during development. Calcium-dependent, bicuculline insensitive/GABAB binding was reduced
during this period in a manner consistent with a decrease in synaptogenesis but appeared to have
recovered at maturity. Calcium-independent, bicuculline-sensitive/GABAA binding, while
unaffected during development was increased in the adult animals suggestive of ‘acute’ rather
than structural lead effects.
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Vol 119 parts 3-4, pp.165-166
[1987]
[Return to Volume’s Index]
Doctorial Thesis Abstract (University of Sydney): Pancreatic Fluid and
Electrolyte Secretion
K.T.F.P. Seow
The isolate, vascularly perfused rat pancreas requires adequate perfusion in order to achieve a
secretory response that is compatible with the in vivo secretory rate. Perfusion rates of 7.4 – 5.2
ml/min is adequate for this purpose. However, with perfusion rates lower than 5.2 (3.4 ml/min
was tested), secretory responses of the glands were lower than both the in vivo pancreas and
glands that were perfused at higher rates.
The rat pancreatic ducts, simulated [sic: should be ‘stimulated’?] by secretin (4.0 nmol/l), require
the simultaneous presence of extracellular HCO3- and Cl- for maximum secretion. Acetate alone
or when used as a replacement for either HCO3- or Cl-, was only capable of supporting about
53% of control fluid output during secretin stimulation. Cl- alone supported only minimal
secretion (7%). The pancreatic ductal secretion in the rat is not sensitive to furosemide (1
nmol/l). Therefore the inhibition of fluid secretion during Cl- withdrawal cannot be due to a
non-operative Na-Cl symport. This symport, so well defined in tissue such as shark rectal gland,
kidney tubule and mandibular gland is sensitive to furosemide. This results can best be explained
by postulating a system of paired antiports, Na+/B+ and Cl-/HCO3<sup-, located in the
basolateral membrane, an anion channel in the luminal membrane (probably HCO3<sup-selective and of limited conductance) and tight junctions of poor cation-selectivity. Studies with
specific ihhibitors like amiloride, (Na+/B+ blocker) and SITS (B+ and Cl-/HCO3<sup- blocker)
show that the pancreatic secretion is sensitive to those inhibitors (Evans & Young, Proc. Aust.
Physiol. Pharmacol. Soc., 1985).
The rate acinar was stimulated with an analogue of cholecystokinin, caerulein (17.7 psol/l). In
contrast to the ducts, it shows no requirement for extracellular HCO3-. However, Cl- is essential
for fluid secretion at this site its requirement is specific as other halide (Br- and I -) were unable
to support secretion to any significant extent when used to replace Cl-. Other anions used such
as isethionate, gluconate and melthylsuplphate were similar tot e halides substitutions. The fluid
secretion in the acini is sensitive to furosemite and its analogues, piretanide and numetanide,
suggesting that a Na/Cl- symport is responsible for salt translocation and thus fluid secretion.
Whatever the furosemide sensitive transport process may involve, this transport protein(s) is
more sensitive to furosemide in the absence of extracellular HCO3- than in its presence. The half
maximal inhibitory cncentrations for the “loop” diuretics studied were increased by some
thenfold in the presence of HCO3-. In the absence of extracellular HCO3- amiloride,
methazolamide and SITS were equally effective in inhibiting fluid secretion. However, in the
presence of HCO3- amiloride was more potent than SITS or methazolamide. This change in
inhibitor sensitivity is probably due to the dependence of secretion on the production of HCO3from metabolic CO2 when the extracellular HCO3- is absent. It is proposed that acini also secrete
fluid like the ducts by a system of paired antiports (Na+/H+ and Cl-/HCO3-) but with a Cl-selective luminal channel. The inhibitory action of the “loop” diuratics on secretion can be
attributed to the inhibition of Cl-/HCO3- antiport and carbonic anhydrase for which furosemide
has been shown to act.
In addition to the change in sensitivity of acinar secretion to “loop” diuretics by extracellular
HCO3-, the inhibitory effect of these drugs are different, at least for piretanide. Instead of a
simple one step inhibition, a biphasic inhibition was observed. Furosemide appeared not to have
such an action while that of piretanide was pronouced and bumetanide was intermediate.
When isenthionate was used as extracellular Cl- replacement, some pancreases showed large
secretory responses 30 minutes after the start of caerulein stimulation. Isethionate entered the
cytoplasm of pancreatic tissue, at least fome compartment not accessible to inulin. The
occupation of this space was unaffected by the Cl-/HCO3- antiport blocker, SITS (0.1 nmol/l).
Its distribution in the pancreatic tissue appeared to be passive diffusion of the undissociated acid
similar to weak acids such as acetic acid. With the aid of an alternative experimental protocol
which reduced the exposure time of the pancreas to isethionate solution, it was shown that
isethionate was not capable of supporting acinar secretion. The large secretory responses seen in
some pancreases were experimentally induced artifact due to the loss of epithelial integrity. This
allowed ultrafiltration to contribute significantly to secretion, if not entirely.
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Vol 119 parts 3-4, pp.167-168
[1987]
[Return to Volume’s Index]
Doctoral Thesis Abstract (University of Sydney): Fitness Components of
Chromosomal Homozygotes In Drosophila melanogaster In Age Structured
Populations
LEIGH PASCOE
This thesis is concerned with the measurement of fitness components of second Chromosome
homozygotes of D. melanogaster in population cages. The fitness components are of intrinsic
interest as an explanation of the observed fitness depression in chromosome homozygotes.
Additionally however, the population cages are a suitable system in which to investigate the
problems of estimating fitness components in populations with continuous generations.
The principal experimental result of this thesis is that relative viability of larvae is a major
contributor to the lowered fitness of chromosome homozygotes. The result was unexpected as
test crosses of non lethal bearing chromosomes give relative viabilities close to unity. Relative
viability appears to be density dependent and under cage conditions is considerably lower than
values observed in low density test crosses. For a sample of lines studied the relative viability
under cage conditions was .432±.113 compared with relative viability under sampling densities of
.901±.040.
Analysis of cage sample frequencies shows that the cage test is a repeatable fitness measure,
however it may give biased estimates if the relative viability estimates differ from that actually
experienced in samples or if an inappropriate model is being used. In two lines studied parental
crowding leads to a reduced relative viability among progeny and if this observation is a general
one past estimates of fitness may be downwardly biased. The parental crowding effect could also
be the reason for consistently negative fitness estimates in some lines, although the use of
inappropriate models can lead to the same result.
A further observation in all lines studied was that the complex inversions in the balancer
chromosome, or some other factor, leads to a reduced absolute viability of progeny from SM1/+
females. This observation could be of some relevance to the low fitness of SM1/+ genotypes
relative to random heterozygotes.
Adult fitness components were also found to contribute to the lowered fitness of the
homozygotes. Mean male mating ability in 3 lines studied was .413±.054 while mean female
fecundity of 5 lines was .482±.044.
In tests of male mating ability the conditions of the test and the method of scoring can markedly
affect the results. A simple mating model is proposed to explain these observations and the
scoring of first matings in a number of test is the recommended method. Three methods of
assessing female fecundity were examined for efficiency by the maximum likelihood method and
subsequent experiments indicated that relative fecundity is not unduly sensitive to frequency, but
is affected by density. Experiments were also carried out on age specific rates of mortality and
fecundity for three of the lines studied. The fecundity of homozygotes was consistently below
that of heterzygotes, but relative values could be expected to increase with age. Adult mortality
did not differ between the sexes for two of the lines but in a third line females suffered a much
higher death rate. The latter line also experienced a heavier mortality overall than the other two.
For the lines in which sufficient information was obtained to predict overall fitness from the
components a value of .193 was predicted. This compares favorably with the observed mean
fitness of .194 and implies an inbreeding depression of 81%. Of the observed inbreeding
depression, 51% may be attributed to reduced relative viability in both sexes and 49% is due to
adult components. The latter figure may be further subdivided into 23% in female and 26% in
male adult fitness components.
In the thesis I have also looked at age specific models of selection in populations subject to
density dependent control of numbers. The control of population size is assumed to affect all
genotypes equally so that selection could be described as density independent. Nevertheless the
relative fitnesses in the population are dependent on the specific model of population regulation
assumed. This result arises because of changes in the age structure of the equilibrium population
(Charlesworth and Giesel 1972a,b). In a regulated population the weighting given to
reproduction at a particular age may be greater than, equal to or less than that in an expanding
population and consequently early reproduction will vary in importance in the different models.
Specifically, a gene which causes a shift forward in the whole reproductive schedule, but which
has no other effect on the vital rates, will not always be favored by natural selection.
The model is also extended to include density dependent control in two critical age groups in the
population. This model, in which mortality in each group depends on a limiting resource unique
to each group, is used to explain the experimental observations of Ayala (1970) that population
size is independently affected by variation in food and living space.
It is argued in the thesis that the measurement of fitness in populations with continuous
generations requires studies on the manner in which population numbers are regulated and
measurement of age specific vital rates.
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Vol 119 parts 3-4, p. 169
[1987]
[Return to Volume’s Index]
M.Sc. Thesis Abstract (University of Sydney): Photographic Measurements of
Bubble Populations from Oceanic Whitecaps
Andrew Walsh
A photographic technique was used to measure bubble size spectra at depths of 0.5 – 2.0 m in
windspeeds of 2-14 ms-1. Sampled bubble populations were fond to be highly variable with time.
The bubble density was found to be a strong function of windspeed, W, varying as W3.3 and few
bubbles were found below 6 ms-1. For wind speeds between 6 ms-1 and 14 ms-1 the total air
volume entrained by bubbles increased as W4.9.The state of development of the wave height
spectrum also appeared to influence the bubble density. Bubble size spectra varied with radius, r,
on average, as r-4. The more limited oceanic results of previous workers are compatible with
these findings.
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Vol 120 parts 3-4, p.147 [1988]
[Return to Volume’s Index]
Doctoral Thesis Abstract (The Australian National University): A Stochastic
Analysis of Scoring Systems
G. H. POLLARD
Many scoring systems can be seen as statistical tests of hypotheses. In tennis singles, for
example, the scoring system used can be seen as a test involving two binomial probabilities pa
and pb where pa(pb ) is the probability player A (player B) wins a point initiated by player A (player
B). Tennis singles is thus a “bipoints” game. The tennis scoring system is an inefficient test
relative to the sequential probability ratio test (SPRT) based on pairs of these points. When pa +
pb > 1 (the tennis context), an SPRT based on the “play-the-loser” (PL) rule is super-efficient.
Chapter 2 shows that when pa + pb > 1 there is in fact a spectrum of superefficient tests (with
even durations) based on “partialPL”(PPL) rules. The most efficient tests within this spectrum,
when pa + pb > 1 , are the SPRT based on the (full) PL rule. Chapter 3 extends this spectrum of
tests to produce the total spectrum of tests (including those with odd durations).
Points within the tennis scoring system have different “importances” whereas points within any
member of the above (efficient) spectrum of PPL systems are equally “important” when pa = pb .
Intuitively, the differing importances of the points within the tennis scoring system contribute to
the inefficiency of that system. Chapter 4 establishes a relationship between the efficiency of a
bipoints scoring system and the importances of the points within it; a relationship which is used
in Chapter 5 to show that the SPRT based on the PL rule has an optimal efficiency property
when pa + pb > 1. Thus chapter 5 solves the classical hypothesis testing problem of finding the
most powerful test for determining the greater of two binomial probabilities.
Chapter 6 shows that some complex SPRT systems can be decomposed into smaller
independent components called “modules” which can in turn be analysed to produce values
from which the asymptotic efficiency of the complete SPRT system can be evaluated. This
module approach is then used in Chapter 7 to address the question as to whether the
superefficiency of the PL rule carries over to the case of tennis doubles.
The particular scoring system used in tennis is analysed in detail in Chapter 8 and the
methodolgy used is seen to be useful for analysing any “nested” scoring system (e.g. tennis is 3nested: points-games-sets). A new tennis scoring system is also proposed.
Chapter 9 contains a brief discussion of some of the characteristics the designer of a scoring
system needs to consider. The study of the importances of points is extended in Chapter 10 and
in Chapter 11 team play with associated countback rules is investigated.
In Chapter 12 it is shown that the classical scoring system used in multiple choice examinations
can be considerably improved by modifying that scoring system and instructing the examinees to
cross any boxes known to be incorrect when the correct box for that question is unknown.
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Vol 120 parts 3-4, p. 148
[1988]
[Return to Volume’s Index]
M.Sc. Thesis Abstract (The University of Sydney): Ultra-Violet and lhetile
Pollination Guides of Some Fabaceae
D. S. GIBBONS
The pollination ecology of eighty species, from ten tribes of the Family Fabaceae are investigated
in relation to their coevolutionary development with some native and the feral member of the
Super Family Apoidea. The literature relating to descriptive analysis of spectral polymorphism is
reviewed and mention is made of the history of Australian Pollination Ecology till 1979.
Apparently integrated anatomical and morphological adaptions of flower and vector are
described. In particular the spectral polymorphism, ultrastructure, mictrotopography and
cytology of the flower is examined and the relationship between these and vector vision and
tactile sensitive organs investigated. Three generalised patterns of spectral polymorphism of the
standard occur in the species studied. It is suggested that these correspond to three pollination
strategies based upon different vectors. Microtopography of the petal surface also shows some
distinctive differences and it is suggested that insects orientate themselves on the flower using
the microscopic parallel ridge systems. The tactile sensors on the insect appendages are of a size
consistent with this hypothesis. Vector pressure and ultimate flower pollination is investigated
with the imbalance of pressure applied by the introduced feral bee Apis mellifera suggesting a
negative effect on the native flora and fauna in the Mangrove Creek study area. Statistical analysis
of petal surface striae, vector sensitive hairs and hair tips and pollen size and shape is presented
and conclusions and predictions relating to flower/vector pollination ecology presented.
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Vol 121 parts 1-2, pp. 39-40
[1988]
[Return to Volume’s Index]
Doctoral Thesis Abstract (The University of Sydney): Studies in the
Bioactivation of Chemical Carcinogens: Role of in vitro Cell Mutagenesis
A. M. BONIN
There are many compounds In the environment, particularly pollutants such as polycyclic
aromatic hydrocarbons (PAH) and closely related polycyclic azaaromatics (PAA), which cause
cancer in mammals as well as man. These cancers are believed to result from a series of steps
which commences with bioactivation of these compounds to reactive intermediate metabolites,
followed by reaction of the activated metabolites with critical cellular molecules such as DNA.
Such intermediates are termed “genotoxic” and their affinity for the genetic material of cells is
exploited in a number of “short-term” assays which have been developed for their rapid
detection, employing the induction of mutations as the end point.
The in vitro metabolic activation system employed in mutagenicity assays has long been
considered a serious limitation because of the inherent inability to simulate in vivo metabolism.
One aspect of this thesis describes a study of inducing agents on the mixed function oxidase
(MFO) system which metabolises foreign molecules (xenobiotics) such as the PAH and PAA.
Induction of the MFO in rat liver by the suspect carcinogen, DDT, resulted in a different profile
of mutagenic metabolites compared with the standard inducing agent, Aroclor 1254, as
determined by both mutagenic and metabolic data. DDT-induced liver MFO enzymes failed,
however, to activate the inducing agent itself to a mutagenic intermediate in bacteria
(Salmonella/mutagenicity assay).
Furthermore, guinea pig liver microsomes induced by 3-methyl-cholanthrene (MC) were superior
to Aroclor rat liver microsomes in activating all carcinogenic PAR and PAA substances tested to
mutagens. The weak carcinogen, benz[c]acridine, was also mutagenic, but only when activated by
this preparation.
Another aspect of this thesis reports on a study of the efficacy of mutagenesis assays using
bacteria and cultured mammalian (V79) cells in the elucidation of the metabolic pathway
whereby two specific PAA, 7MBAC (7-methylbenz[c]acridine) and DRAJAC
(dibenz[a,j]acridine) are activated to their ultimate reactive intermediates. Mutagenicity results of
synthetic metabolites obtained in both assays implicate bay region diol epoxide formation as a
major bioactivation pathway for these compounds, consistent with the bay region theory of
carcinogenicity which has been proposed for PAH generally.
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Vol 121 parts 1-2, p. 41[1988]
[Return to Volume’s Index]
Doctoral Thesis Abstract (The University of Sydney): Crystal Growth and
Aerodynamics of Drug Particles
HAK-KIM CHAN
Solid forms of three therapeutic agents were studied for crystal habit modifications and/or
aerodynamic properties with the aim to improve the therapeutic efficiency in direct pulmonary
administration.
Firstly, cromaglycic acid (CA), characterized by physical and chemical methods, was prepared in
forms of elongated fibrous particles suitable for inhalation. The fibres have a geometric standard
deviation (σg) = 1.88 and a mass median aerodynamic diameter (MMAD) = 0.65μm which is in
the respirable range. As compared to the currently used sodium cromoglycate, CA has a much
lower aqueous solubility which thus minimizes the hygroscopic growth of the drug particles and
favours the pulmonary deposition that may offer a therapeutic advantage. Theoretical
calculations of the aerodynamic diameters indicate that the calculated MMAD and σg assuming a
perpendicular flight orientation of the fibres are in reasonable agreement with the values
obtained by cascade impactor.
Secondly, three solid forms of methotrexate (MTX), a widely used chemotherapeutic agent, were
found and characterized: tetragonal crystals from hot water crystallization; the original powder
with a lower degree of crystallinity from the manufacturer, and an amorphous powder from
methanol. Single crystals were prepared with size sufficiently large for the structure to be solved
by X-ray diffraction. The results show that conformation of MTX molecules in the crystal is a
potential energy minimum and is similar to the proposed structure of dihydrofolate bound to
dihydrofolate reductase (DHFR). These results are in disagreement with theoretical studies
which suggested that the bound forms of MTX were highly strained, and are therefore of
importance to those attempting to design new inhibitor of DHFR. Subsequent habit
modification of MTX crystals using various crystallization conditions revealed a similar rounding
effect on crystal habit by different additives. The results suggest that rounding of drug particle
may be possible simply by using additives during crystallization. This might be useful
pharmaceutically for preparing spherical particles to improve the handling and processin
characteristics of crystalline solids.
Lastly, mechanistic studies of the formation of 2 distinct crystal habits of
hexamethylmelamine(HMM) in different solvents revealed that growth of compact crystals in
both polar and non-polar solvents is controlled by volume diffusion. Formation of needle
crystals on fast evaporation from polar solvents is the result of diffusion controlled growth along
the [0001] direction and surface controlled growth along the [1100] direction. Discrepancies were
found between the α-values and the observed growth rates, which may be attributed to volume
diffusion. Solute-solvent interactions in solutions are found to be very weak and no statistically
predominant stereospecific interaction can be identified as responsible for the habit
modifications in different solvents. A solvate of HMM-hexafluorobenzene was also identified.
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Vol 121 parts 1-2, p. 43[1988]
[Return to Volume’s Index]
Doctoral Thesis Abstract (The University of Sydney): Kinetic Aspects of
Calcium Metabolism in Forage Fed Sheep
JEREMY STORER CHRISP
Calcium kinetics in forage fed sheep were investigated by an isotopic dilution technique in three
trials. The data from the two lactation and one growth trials were analysed by compartmental
analysis using the SAAM program (Simulation Analysis and Modelling). During early lactation
(trial one) calcium metabolism was determined in Poll dorset ewes consuming either fresh
ryegrass-white clover (Dry Matter Digestibility: DMD = 71% and calcium content: Ca = 5.48
mg/g DM) or greenfeed oats (DMD = 69% and Ca = 3.79 mg/g DM). The importance of
supplementary protein to the metabolism of calcium in ewes consuming clover swards was also
investigated and further examined in trial two. In the third trial, net faecal endogenous loss of
calcium was estimated in Romney wether hoggets consuming either fresh herbage (DMD = 73%
& Ca = 12.1 mg/g DM) or a conserved forage (DMD = 57% & Ca 6.41 mg/g DM). These latter
diets were selected to provide variation in the amount of indigestible matter and calcium passing
through the gastrointestinal tract.
In the first lactation trial, protein supplementation (100 g/d/head of protected casein per os.)
served to increase milk production by up to 24% and changed the rates of calcium transport.
The gastrointestinal calcium absorption rate increased (mean +/- s.e.m.: 51.8 +/- 15.3 v 75.4
+/- 4.4 mg/d/kg LW for control & protein groups, respectively) as did skeletal calcium
accretion (41.7 +/- 3.8 v 48.6 +/- 5.3 mg/d/kg LW, respectively). Skeletal resorption decreased
(66.9 +/- 14.4 v 59.9 +/- 8.6 mg/d/kg LW, respectively) and the overall calcium balance
improved (-25.2 +/- 17.2 v -11.5 +/~ 4.2 mg/d/kg LW, respectively). In the second lactation
trial, unprotected casein was infused (100 g/d/head abomasally) and milk production was
balanced between control and supplemented groups offered a similar ryegrass-white clover
herbage (DMD = 78% and Ca = 6.47 mg/d DM). Protein supplementation consistently altered
the rates of calcium transport in both these trials but not to a significant extent. This was despite
a significant improvement in nitrogen balance. Possible reasons for this include: the preference
of supplementary casein for energy metabolism rather than for bone matrix synthesis, the
suitability of casein as a source of amino acid for this synthesis, or alternatively, that bone
mineral losses are inevitable during early lactation.
The availability of dietary calcium from the greenfeed oats was lower than that from the ryegrasswhite clover (17 v 19%, respectively). This was unexpected both because of the lower calcium
content of the oats and also the high requirement for calcium which resulted from high levels of
milk production. All availability values obtained were much lower than the current Agricultural
Research Councils value of 68%. The term, availability, was discussed as to its meaning and
value.
Net faecal endogenous loss of calcium varied with dry matter intake in the wethers (196 to 53.6
mg/d/kg LW). When data from all the three trials were combined, the best predictor of
endogenous loss was faecal calcium output. A distinction was made between the parameter of
net faecal endogenous loss as opposed to a gastrointestinal secretion of calcium and the
relationship between these two identities was also examined.
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Vol 121 parts 1-2, p. 45 [1988]
[Return to Volume’s Index]
Doctoral Thesis Abstract (The University of Sydney): Observations of Alfvén
Waves in a Tokamak Plasma
A. B. MURPHY
In order to heat a tokamak plasma to the temperatures required for thermonuclear fusion to
occur, a source of energy additional to the ohmic heating due to the current flowing through the
plasma will almost certainly be required. Radiofrequency heating through the excitation of
Alfvén waves is a possible means of providing this power.
The thesis is predominately concerned with an experimental investigation of the excitation and
propagation of Alfv’en waves in a tokamak plasma, and in particular the potential application of
Alfvén waves to the heating of a fusion plasma.
A general introduction to the Alfvén wave heating scheme and its theoretical basis is given. A
detailed discussion of the effect of a low density edge plasma (which is normally present in a
tokamak) on the compressional Alfvén wave dispersion relation is presented.
The TORTUS tokamak, and the radiofrequency apparatus and procedures employed in the
experiments, are described in detail. The construction of the antennas used, and their properties
in the absence of a plasma, are discussed.
Experimental investigations of the plasma loading of a large number of antenna configurations
are presented. It is demonstrated that the anomalously large resistive and inductive loading of
some antenna configurations is due to the connection of extra current paths by the plasma. The
dependence of antenna loading on antenna configuration and excitation frequency, and plasma
parameters, is discussed.
Measurements of the poloidal and radial distribution of the magnetic fields associated with the
waves excited by a Faraday shielded antenna, oriented in a poloidal plane of the tokamak, are
presented. It is shown that the antenna directly couples to the torsional Alfvén wave, which
propagates along magnetic field lines in the edge plasma. The antenna excitation frequency and
plasma electron density dependence of this undesirable coupling is investigated. Means of
minimising the coupling are suggested.
Coupling of energy from the antenna to Alfvén resonance surfaces well inside the central plasma
(as required for Alfvén wave heating) is also observed, through significant wave field
enhancement at the theoretically predicted radii. Experiments utilising a phased array of three
toroidally spaced antennas indicate that energy is coupled to the Alvén resonance surfaces
through excitation of the surface branch of the compressional Alfvén wave. A significant
proportion of the total wave energy is shown to be coupled to surfaces well inside the central
plasma, which is a result favourable to the prospects of the Alvén wave heating scheme.
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Vol 121 part 4, pp.185 [1989]
[Return to Volume’s Index]
M.Sc. Thesis Abstract (The University of Sydney): Characterisation of Urban
Storm Water Run-Off Quality, Jamieson Park, N.S.W.
R. McNamara
During 1983 and 1984 the State Pollution Control Commission collected urban runoff water
quality data from Jamison Park, a 17.1 hectare recently developed residential catchment in
Sydney’s outer western suburbs. Additional water quality data was collected during 1986 and
1987. Initial analysis indicated the significance of the urban environment as a source of pollution,
with soluble pollutant concentrations (NH3–N, NOx–N and O.P) comparable to secondary
treated sewage and suspended solids (NFR) been comparable to raw sewage. This was further
demonstrated when pollutant loads were determined. For example, on the basis of this data it
was estimated that about 680 kg/ha of suspended solids and 2.7 kg/ha of free ammonia would
be removed via runoff from this catchment in a normal rainfall year. These values were
consistent with those reported in both the local and international literature.
When the data was examined for temporal variations it was found that a first flush, i.e., highest
concentrations in initial runoff, existed in all pollutants examined. In terms of load, about 45 60% of the total pollution load was removed by the initial 50% of runoff for most storm events
sampled. It was found that pollutants washed out of the atmosphere by initial rainfall as well as a
standing load of pollutants in the in-pipe drainage network that are rapidly mobilised by initial
runoff were partly responsible for the first flush. Furthermore, when the upper reaches of the
catchment begin to contribute runoff to the outlet hydrograph pollutants from this area are been
diluted by relatively clean water that is been delivered from the lower reaches. When the
infiltration rate of this catchment was overcome (> 5 mm rainfall intensity) or when field
capacity was reached (10 - 12 mm of rainfall) a second flush in both suspended solids and
soluble pollutants was observed, with about 40% of the total storm pollution load been
associated with this second peak. Therefore, urban runoff water quality is conceptually a two
stage process with a first flush of pollutants from impervious areas and a second flush of
pollutants from pervious parts of the catchment if the infiltration rate is overcome or if field
capacity is reached. The implication of these findings for pollution abatement stratergies are that
if a catchments “typical hydrograph” is comprised of runoff from both impervious and pervious
areas then abatement measures will need to consider the pollution in runoff from both these
sources.
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Vol 121 part 4, pp.59 [1989]
[Return to Volume’s Index]
M.Sc. Thesis (The University of Sydney): Paleoecological Studies of the
Ordovician Fossil Hill Limestone, Central New South Wales
LEI YUE
The thesis incorporates the paleoecology of the Upper Ordovician Fossil Hill Limestone
Formation, Cliefden Caves area, central New South Wales, with an appendix dealing with a
group of new fossils Polylappetida Yue, Ord. Nov..
First, the biostrome in the Kalimna Limestone Member on Fossil Hill is entirely dominated by
and composed of large in situ colonies of Tetradium cribriforme, which occupy some 90% of the
biovolume. The minor elements stromatoporoid Cystistroma, corals Bajgolia, Hillophyll um,
Nyctopora, the stromatolite Cliefdenia, together with brachiopods, bryozoans, gastropods,
ostracodes and calcareous algae, occupy the interspaces of thein situ colonies of T. cribriforme. The
slender columns of the stromatolite Cliefdenia cluster, the presence of birdseye’s structures,
diagenetic silts in the matrix, oncoids and algal-coated grains suggest the low sedimentation,
shallow water origin of the biostrome.
Second, the algal-coated grain mounds of the Taplow Limestone Member to the west of the
Boonderoo shearing shed produce a unique group of the coated grain deposits in the geological
history. Three types of algal-coated grains are described and interpreted: 1) spherical dense
coated grains; 2) subspherical-spherical loose coated grains; 3) spongy algal-coated grains. The
type of the coated grains is controlled by the shape of the skeletal cores and the energy level. The
elongated skeletons tend to be the core of the loose and spongy coated grains and the spherical subspherical skeletons are related to dense coated grains. The higher the energy, the higher
proportion of the dense coated grains. The lime mudstone mounds of the member produces a
unique group of fossils: Polylappetida Yue, Ord. Nov.. The new order includes one family:
Polylappetidae Yue, Fam. Nov., four genera and six species: Cliefdenoconus regularis Yue, gen. et sp.
nov., Dianfanoconus wyomingensis Yue, gen. et sp., Linoconus erectus Yue, gen. et sp.nov. Hillophyllum
taplowensis Yue, gen et sp. nov., Hillophyllum regularis Yue, gen. et sp. nov. H. dunhillensis Yue, gen.
et sp. nov..
Last, the six specific coral/stromatoporoid associations from the Dunhill Bluff Limestone
Member to the west of the Boonderoo shearing shed have been recognized: 1) Cliefdeniadominated association; 2) Nyctopora-Labechiella association; 3) Coccoseris-Labechiella-Sphaerocodillum
association; 4)Stratodictyon-Labechiella association; 5) Labechiella-Coccoseris association; 6) LabechiellaTetradium association.
Vol 122 parts 1-2, p.122 [1989]
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Doctoral Thesis Abstract: A new Approach to Transient Electrum Spin
Resonance Spectroscopy
JUDITH M. DAWES
Transient electron spin resonance (esr) offers the most general method for the detection of short
lived reactive free radicals, which are common chemical intermediates. It is currently limited to
10 to 100 ns time resolution by the lack of suitable high power short pulsed microwave sources,
and by the dead time associated with cavity resonances of these sources. In this thesis, a new
approach to overcome these problems is presented. A laser driven semiconductor device has
been designed to produce subnanosecond microwave pulses, for use in time resolved esr
experiments.
Microstripline technology has been adopted for both the sample cell and microwave detection as
well m for the microwave pulse generator. This offers advantages of broad bandwidth, low loss
and high power handling capability. It also enables access to the sample by a laser photolysis
pulse. As the laser pulse is synchronized with the microwave pulse, it is possible to study the
kinetics of reaction intermediates by optical pump – microwave probe spectroscopy.
Since the microwave pulse generator depends on semiconductor photoconductivity, some simple
photoconductive devices were investigated experimentally. The charge carrier recombination,
which governs the long time behaviour of these switches, was theoretically modelled in two and
three dimensions for comparison.
The devices for microwave generation, absorption and detection were constructed using
microlithography techniques. These devices were characterized and tested experimentally.
The lasers which were developed to drive the microwave generator are also described. A mode
locked, Q-switched and cavity dumped laser operating with high power and stability at a
repetition rate of up to 12 kHz, was used to pump a dye laser amplifier to provide short pulses of
sufficient energy for microwave generation. Some pulse compression experiments using optical
fibre were also performed to investigate the potential of chirped pulse amplification.
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Vol 122 parts 1-2, p.77 [1989]
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M.Sc. Thesis Abstract: Rheological of Coagulated Colloidal Suspensions
DAVID EVERETT
Monodisperse spherical colloids were prepared (poly-styrene and poly-methyl methacrylate by
emulsion polymerisation techniques and coagulated by the addition of cationic surfactant, cetyl
trimethyl ammonium bromide (CTAB), or by compression of the double layer as a consequence
of increasing the ionic strength. The elastic shear modulus (G) was measured on coagulated
samples using a pulse shearometer and compared with viscous data obtained from a couette
viscometer. Both elastic and viscous parameters were related to colloid chemical parameters such
as particle radius, particle volume fraction and the zeta potential. Values for shear modulus were
compared with a previously developed semiempirical model based on viscous parameters, and
some correlation was observed. A model was developed to predict the primary yield stress of a
coagulated sal as a function of the zeta potential and volume fraction. Yield stress values from
the model were in reasonable agreement with estimates obtained from viscous data, measured
using a constant stress Deer rheameter.
Shear modulus was measured for different volume fractions and was found to be proportional to
volume fraction to the power of 2.6 at constant zeta potential. This was explained by assuming
the existence of regions of close packed particles within the internal floc structure of a
coagulated sal. A model was developed to describe the increasing G values over time in terms of
the kinetics of interparticle bond formation. This model enabled estimates to be made of the
energy barrier to coagulation of the diffusion controlled process at different zeta patentials.
Values obtained were of order 3 kT.
Rhealogical measurements were performed on coagulated kaolinite mineral suspensions as a
function of pH and ionic strength. Time dependent shear modulus experiments were performed
using the pulse shearometer, and the results were explained in terms of different charges on the
kaolinite surface and the subsequent variations in aggregate structure.
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Vol 122 parts 1-2, p.79 [1989]
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Doctoral Thesis Abstract: Transmembrane Chemical Shift Differences in the
31P NMR Spectra of Erythrocyte Suspensions: Origins and Applications
KIARAN KIRK
Trimethyl phosphate, triethyl phosphate, dimethyl methylphosphonate, diethyl
methylphosphonate, trimethylphosphine oxide and the hypophosphite, phenylphosphinate and
diphenylphosphinate ions all contain the phosphoryl functional group. When added to a
suspension of intact human erythrocytes at WC, seven of these eight compounds (the exception
being triethyl phosphate) gave rise to intra- and extracellular 31P NMR resonances that differed in
their chemical shifts. Triethyl phosphate added to an erythrocyte suspension gave rise to only a
single 31P NMR resonance; the significantly different intra- and extracellular chemical shifts were
averaged by the fast transport of the compound across the cell membrane. The intra- and
extracellular chemical shifts of the phosphoryl compounds varied with the haematocrit, osmotic
pressure and temperature of the suspension, as did the difference between the intra- and
extracellular chemical shifts.
The transmembrane chemical shift differences could not be attributed to the operation of any
single mechanism but, rather, resulted from a combination of different effects. For
carbonmonoxygenated cells suspended in physiological saline, the magnetic susceptibility of the
intracellula? compartment was lower than that of the extracellular compartment, largely as a
result of the diamagnetic susceptibility of intracellular haemoglobin. The corresponding
difference between the bulk magnetic field in the two compartments was less than that calculated
using a simple two-compartment model. It was sufficient to account for most (if not all) of the
relatively small difference between the intra- and extracellular chemical shifts of trimethyl
phosphate and triethyl phosphate, but the same was not true for the other six compounds of
interest. Despite obvious structural similarities between the eight compounds, the
transmembrane chemical shift differences for the phosphonates, phosphinates, phosphite and
phosphine oxide were very much larger than that for the two phosphates and, therefore, larger
than could be accounted for by magnetic susceptibility effects alone. For these other phosphoryl
compounds an additional effect was operating to cause the intra- and extracellular chemical shifts
to differ. The various intra- and extracellular solutes were shown to influence the 31P NMR
chemical shifts of these compounds to different extents by a susceptibility-independent
mechanism. The largest such effect was that exerted by haemoglobin, which was therefore
identified as being the agent primarily responsible for the transmembrane chemical shift
differences. Lysozyme was shown to exert a similar (susceptibility-independent) effect on the
phosphoryl chemical shifts; it therefore seems likely that the effect involves a property of
proteins in general and not a property unique to haemoglobin.
In experiments with a range of different solvents, it was demonstrated that the 31P NMR
chemical shifts of trimethyl phosphate and triethyl phosphate were entirely insensitive to factors
affecting the formation of hydrogen bonds at the phosphoryl oxygen atom. The same was not
true of the other six compounds; their 31P NMR chemical shifts decreased markedly in response
to any disruption of hydrogen bonding. It was therefore proposed that haemoglobin exerted its
susceptibility-independent chemical shift effects by perturbing the hydrogen bonding of the
phosphoryl groups to solvent water. Such a hypothesis accounts for the lack of a significant
susceptibility-independent effect of haemoglobin on the 31P NMR chemical shifts of the two
phosphates.
Irrespective of the origin of the transmembrane chemical shift differences, the phenomenon was
shown to have a number of useful applications. The observation of separate 31P NMR
resonances for the intra- and extracellular populations of the hypophosphite ion allowed the
estimation of the relative concentrations of hypophosphite in the intra- and extracellular
compartments. Incorporation of the hypophosphite distribution ratio into the Nemst equation
yielded an estimate of the membrane potential. The cell volume-dependence of the
transmembrane chemical shift difference for dimethyl methylphosphonate was shown to provide
a convenient means of monitoring cell volume changes using 31P NMR spectroscopy.
Furthermore, the separation of the intra- and extracellular resonances of dimethyl
methylphosphonate allowed the application of the NMR saturation transfer technique to
measuring and characterising the equilibrium exchange of the compound across the erythrocyte
membrane. The results of the transport measurements were fully consistent with the hypothesis
that the molecule crosses the membrane solely by a process of simple diffusion through the lipid
bilayer.
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