Second Kamal A. Shair Central Research Science Laboratory Research Conference.
Research Vision
Saturday 14 May 2011
Hostler Auditorium.
Abstracts.
TALKS
Vision for research
Rose-Mary Boustany
Neurogenetics program and division of pediatric neurology
Departments of pediatrics and biochemistry, FM, AUB.
My vision for research is for a community of “scientists without borders”. This not
only applies to geography but also to the previously dogmatically held beliefs of clearly
demarcated disciplines of molecular biology, chemistry, cell biology, physiology. My
journey in science has not been a traditional one. I started out as a clinician who was
drawn into basic science because I wanted fundamental questions answered that my ivory
tower colleagues in the sciences would not get excited about. My clinical training was in
neurology and genetics, a.k.a. neurogenetics. As a young Assistant Professor at HMS,
and then Duke, I realized I had to step back and become a basic scientist. Molecular
biology was de rigueur at the time. I acquired that skill first. It helped identify genes and
mutations of the neuronal ceroid lipofuscinoses (NCLs), a group of deadly progressive
neurological disorders. That became insufficient although it opened the door for further
scientific research. One had to learn the tools of biochemistry, cell biology, then
signaling, lipid biochemistry and be ably to apply them all to one project to make
headway. We will illustrate with examples from our work in identifying the CLN3 gene
defective in the juvenile form of this disease or JNCL. The second valuable lesson I
learnt was studying obscure diseases, like the NCLs, can have huge payoffs This
protein we ultimately established is antiapoptotic. Antiapoptotic drugs or treatments
uncovered to be helpful in this disorder can be effective in many other neurodegenerative
disorders. As neurodegenerative disorders and cancer are two sides of the same coin, the
CLN3 gene defective in JNCL is upregulated in many cancers, and presently is being
developed as a biomarker for breast cancer in Lebanese women. A third lesson or
important conclusion is that all our scientific endeavors evoke much more excitement,
passion and support when they are in the service of man and womankind. A fourth and
valuable lesson is one has to continuously learn and be open to new ideas and
technologies. After struggling with a scientific problem or problems for a decade novel
technologies like microarray anaylsis of copy number variations and homozygosity
mapping as well as second generation sequencing can solve problems in one or two
experiments. A novel NCL (CLN9) variant that had eluded us for 10 years was finally
cracked using these technologies a few months ago. Also, the study of the genetics of
autism, seemingly complex and impossible just a decade ago, is now yielding scores of
new autism susceptibility genes, and in our hands, in the Lebanese population as well.
I was lost and now I'm found
El Haddad S.1, Khoury M.1, Daoud M.1, Kantar R.1, Mousallem T.2, Alzate O.4 and
Boustany RM.1,2,3
1
Neurogenetics Program and Division of Pediatric Neurology, Departments of Pediatrics
and Biochemistry, American University of Beirut, Beirut, Lebanon. 2 Duke University
Medical Center, Departments of 2Pediatrics and 3Neurobiology, Durham, NC, USA, 4
Department of Cell and Developmental Biology, University of North Carolina at Chapel
Hill, Chapel Hill, NC. 27599. USA
A distinct juvenile variant of the Neuronal Ceroid Lipofuscinoses (NCL), CLN9, was
described in 2004 (1). Clinical, pathological and neuroradiological features suggested
this was a new NCL variant. These included a marked increase in growth and apoptosis
rates in patient cells compared to normal controls. At that time, CLN5 was thought to be
a rare NCL variant with predominant incidence in Finland. DNA from CLN5 patients
was not available for comparison by genechip analysis. Efforts at identifying the gene
responsible for CLN9 resulted in the delineation of a number of candidate genes, none of
which were mutated in the CLN9 patient DNA.With the current marked increase in
resolution of microarray technology we embarked on homozygosity mapping of the DNA
from our patients and their families. Homozygosity mapping revealed a long contiguous
stretch of homozygosity on chromosome 13 common to probands and absent in the
parents and the non-affected siblings. This area harbored the CLN5 locus. Sequencing of
the exons and promoter revealed a substitution in Exon 3 leading to a novel premature
stop codon and a truncated protein. CLN5 overexpression in patient cells corrects growth
and apoptotic abnormalities. The first description of non-Finnish CLN5 cases was first
reported in 2006 (2). In 2010, 14 CLN5 mutations were reported in patients of diverse
ethnic backgrounds, confirming the broad geographical prevalence of CLN5 and
suggesting that it was more heterogeneous than originally expected (3). Previous data on
the biochemistry and cellular biology of what was known as CLN9, still hold true and is
now attributed to this CLN5 variant.
We highlight the role of array based homozygosity mapping in the identification of genes
responsible for rare autosomal recessive disorders.
References:
1. Schulz, A., Dhar, S., Rylova, S., Dbaibo, G., Alroy, J., Hagel, C., Artacho, I.,
Kohlschütter, A., Lin, S. and Boustany, R.-M. Impaired cell adhesion and
apoptosis in a novel CLN9 Batten disease variant. Ann Neurol 2004; 56: 342–350.
2. Bessa, C., Teixeira, C.A.F., Mangas, M., Dias, A., Miranda, M.C., Guimaraes, A.,
Ferreira, J.C., Canas, N., Cabral, P., Ribeiro, M.G. Two novel CLN5 mutations in
a Protuguese patient with vLINCL: Insights into molecular mechanisms of CLN5
deficiency. Mol Genet Metab. 2006; 89: 245-253.
3. Xin, W., Mullen, T.E., Kiely, R., Min, J., Feng, X., Cao, Y., O’Malley L., Shen,
Y., Chu-Shore, C., Mole, S.E., Goebel, H.H., Sims, K. CLN 5 mutations are
frequent in juvenile and late-onset non-Finnish patients with NCL. Neurology
2010; 74: 565-571.
The future of human immunodeficiency virus type 1 (HIV-1) and HBV
vaccines.
HIV-1 Study: Nada M. Melhem1, Kellie N. Smith2, Bonnie A. Colleton3, and Charles
R. Rinaldo Jr2
1
Medical Laboratory Sciences Program, Faculty of Health Sciences, American
University of Beirut, Beirut, Lebanon; 2 Department of Infectious Diseases and
Microbiology, Graduate School of Public Health, University of Pittsburgh, Pittsburgh,
Pennsylvania, USA; 3 Department of Public Health Sciences, Hershey Medical Center,
College of Medicine, Pennsylvania State University, Hershey, Pennsylvania, USA
HBV Study: Nada M. Melhem1, Rami Mahfouz2, Rolla Khatib1, Umayya
Musharrafieh3, Sara Shamra1, Ghassan Hamadeh3, Sami Ramia1.
1
Medical Laboratory Sciences Program, Faculty of Health Sciences, American
University of Beirut, Beirut, Lebanon; 2 Department of Laboratory Medicine and
Pathology, Faculty of Medicine, American University of Beirut, Beirut, Lebanon;
Department of Family Medicine, Faculty of Medicine, American University of Beirut,
Beirut, Lebanon
1 Corresponding author: Nada M. Melhem
HIV-1 Study
Background & Results: The control of human immunodeficiency virus type 1(HIV-1)
replication depends mainly on CD8+ T cell responses specific for immunodominant viral
epitopes. An important challenge in the development of HIV-1 vaccines is the diversity
of clinical isolates coupled with the propensity for the virus to undergo escape mutations
in T cell epitopes through selective pressure in vivo.HIV-1 vaccines that increase the
breadth of epitope-specific T cell responses are likely to contribute to containing HIV-1.
We believe that the stimulation of a broad primary T-cell immune response by monocytederived dendritic cells (DC) loaded with HIV-1 peptide sequences could be important for
an effective HIV-1 vaccine. We demonstrate that DC of HIV-1-naïve adults loaded with
consensus HIV-1 peptides sequences can prime multispecific and polyfunctional CD8+ T
cell responses to HIV-1. Autologous HIV peptide sequences at different time points
during the course of infection were synthesized and evolutionary changes spanning the
viral genome of infected individuals were spotted. These sequences were used in the in
vitro priming assay and we also demonstrate successful in vitro priming of naïve T cells
by DC loaded with HIV-1 variant peptide sequences, in an entirely autologous system.
These results provide critical insights about the use of DC-based vaccines to stimulate the
primary responses of naïve CD8+ T cells to genetically diverse HIV-1 epitopes.
HBV Study
Background and Results: Results from long-term vaccination studies in different
populations showed that non-responsiveness to hepatitis B virus (HBV) vaccination is
common. Moreover, human leukocyte antigen (HLA) allele association with nonresponsiveness as well as response exists with variability observed in different ethnicities.
The interaction between HLA class I and/or class II molecules with different killer cell
immunoglobulin receptors (KIR) have been described among HIV-1 and HCV positive
individuals. Individuals positive for HLA-Bw4-80I and highly expressing the inhibitory
KIR3DL1 on their natural killer (NK) cells, show a slower progress to AIDS. KIR3DS1
with Bw4-80I was reported to protect against disease progression as well as opportunistic
infections in HIV infected subjects. Moreover, KIR2DL3 and its ligand HLA-C1 were
found to affect clearance of hepatitis C virus (HCV) among Caucasians and African
Americans exposed to low doses of the virus. Little is known about these interactions
during the course of HBV infection and following vaccination among responders and
non-responders. Our project aims at understanding the molecular nature of this
interaction in Lebanon. We have recruited 100 individuals, HBV- vaccinated and nonvaccinated. Isolated peripheral blood mononuclear cells (PBMCs) from freshly drawn
blood of the study groups and their matched control group were used for DNA extraction
for the genotyping of HLA Class I, Class II as well as KIR. We are in the process of
testing sera for the titers of anti-HBs as a measure of protection (response to
vaccinations) as well as levels of antibodies directed against the core antigen (anti-HBc )
and HBsAg (surface antigen) as a measure of infection. We will apply correlation
analyses to determine the relationship between levels of protection or non-protection in
the study and control groups in relation with HLA and KIR alleles. The data generated
will offer critical insight to the field of antiviral immunity and will set the stage for future
functional studies on HBV as well as other viruses in Lebanon and the region.
Present and Future Programs of Escherichia coli-Induced Mastitis in Dairy Cattle
Elie K. Barbour
Animal and veterinary sciences department, FAFS, AUB
Mastitis is the inflammation of the mammary gland of both domestic animals and
humans. This disease is present on almost every farm of dairy cows in this world, costing
losses to the world’s dairy industry equivalent to 2.6 billion US dollars/year.
The vision in our current and future programs is to diagnose mastitis (clinical and
subclinical) in dairy cattle of Lebanon, determine the involvement of Escherichia coli
etiologic agents, accomplish procedures to detect virulence genes responsible for
pathogenesis, and attempt to modulate the drug-resistance in these strains, targeting a
future enhancement of drug therapy regimen, and the development of vaccines against
the highly virulent Escherichia coli serotypes. These programs will result in sustainability
of the dairy cattle industry by improving the milk yield and its quality, thus contributing
to the food safety and security strategy of our Lebanese Government.
Escherichia coli-induced mastitis in cows of Lebanon: virulence genes
frequency and antimicrobial resistance modulation
Kassabian, J.T.1, Barbour, E.K. 1, Sleiman, F.T. 1, Hamadeh, S.K.1, Kassaify, Z. 2
1
Animal and Veterinary Sciences Department, FAFS, AUB
2
Nutrition and Food Sciences Department, FAFS, AUB
This is the first research in Lebanon aimed at studying the Escherichia coli-induced
mastitis in cows, frequency of virulence genes, and modulation of antimicrobial
resistance in the etiologic agents. Sixty seven cows were randomly chosen on 10 farms,
present in the four provinces of Lebanon. California Mastitis Test (CMT) was used to
diagnose clinical and subclinical mastitis in different quarters of the cow’s udder.
Isolation and biochemical characterization of Escherichia coli recovered from mastitic
milk samples was concluded. The frequency of eae virulence gene in Escherichia colietiologic agents involved in mastitis was determined. The involvement of K99 serotype
of Escherichia coli in mastitis was studied, due to its role in calf diarrhea, an economic
disease of dairy industry. Modulation of antimicrobial resistance in Escherichia colietiologic agents was successful by using a synergism mechanism of nine natural
substances.
This study established a base-line data on nature of Escherichia coli-virulence genes
frequency, the need for successful vaccination against K99 economic infections, and the
future use of synergistic preparations to change drug resistant-Escherichia coli to
susceptible strains, a new approach that will enhance the success of chemotherapy against
mastitis of cows.
Conservation Agriculture in Lebanon
Isam Bashour and Kassem Jouni
Agricultural Science Department, FAFS, AUB
The German International Cooperation (giz) is sponsoring a program to promote
conservation agriculture (CA) in several countries in the Middle East. The agricultural
science department is the technical partner of the CA program in Lebanon since 2007.
The objectives of the program are to introduce CA the Lebanese farmers and compare the
effect of conventional and CA on: a) water conservation, b) soil degradation, and c)
production cost. Several field experiments were conducted in Beqaa, North, South, and
Mount Lebanon. Results of the last three years indicate that CA increased moisture and
nutrient levels in the soil, gave higher yields for leguminous crops and fruit trees, and at
the same time, reduced cost of production by about $250/ha. More field work and data
will be collected in the coming future to verify the obtained results
Antibiotic uptake by plants from manure-amended soils
Rani Bassil and Isam Bashour
Agricultural science department, FAFS, AUB
Antibiotics have been used in order to treat infectious diseases in both humans and
animals. But with the growth of intensive farming, a significant quantity of these
antibiotics is used on animals as preventative treatments. Most antibiotics fed/injected to
animals are poorly absorbed in the animal gut and substantial amounts of these antibiotics
are excreted in urine and feces, which in turn end up in manure. A study was conducted
to investigate how much of the antibiotics given to animals under Lebanese conditions
(streptomycin and gentamicin) are absorbed by plants. For this purpose, a pot experiment
RCBD was conducted using lettuce, carrot and radish as indicator crops. The results of
this study will shed some light on the uptake of streptomycin and gentamicin, commonly
used antibiotics in Lebanon, and applied to soils via manure on plant quality.
The aquaculture research program at AUB:
What is it all about?
Imad Patrick Saoud
Biology department, FAS, AUB
Aquaculture is defined as the rearing of organisms in water. It includes everything from
rice farming to food production to zoos and aquariums to maintenance of squid for
biomedical research. At the AUB biology department we do aquaculture research for
three main reasons. First, we study the environmental physiology of aquatic organisms in
order to develop optimal protocols for farming them. Second, we determine their
environmental tolerances in order to model their distribution in natural environments
depending on season and location. This also helps forecast invasiveness of the species
and competition with native species. Third, we use aquaculture as a tool to decrease
consumptive water use and increase freshwater productivity in semi-arid and arid regions
of the world. This helps reduce urban migration and increase rural productivity in protein.
In the past few years students working in the aquaculture lab have studied topics ranging
from 1- water temperature effects on fish to 2- energy use relative to water movement, to
3- nutritive requirements of herbivorous marine fish, to 4- intraspecific competition
among schooling fish, to 5- compartmentalization of heavy metals and aromatics within
sea urchins, to 6- variation in omega-3 fatty acids with season and diet, to 7- effects of
water toxins such as ammonia and nitrite on fish, to 8- developing a hematological test
for fish health evaluation to 9- distribution of fertilizing minerals with soil and plant
systems when aquaculture water is used for irrigation. We hope to continue to be one of
the innovative labs in the field. We are today one of the most productive (if not the most
productive) labs in the Arab world and are always open to collaboration with faculty
members and students from AUB and elsewhere. We are always hungry to learn new
techniques and open to new ideas.
Herbal compounds for cancer treatment: an ongoing saga
Hala Gali-Muhtasib
Biology department, FAS, AUB.
Over the past 17 years at the AUB, research in my laboratory has focused on the fields of
cancer chemotherapy and cancer prevention to identifying potential “targets” for
prevention and therapy using plant-derived compounds. Recently, I have been
particularly interested in translational research that specifically aims at understanding the
mechanisms of action of plant-derived anticancer drugs. This basic understanding is then
used to discover new ways for effective treatments, i.e. targeted therapies. I have
researched the biological activities of a multitude of compounds including vitamin E,
thymoquinone from black seed, linalyl acetate and terpeniol from sage, tannins from
perennial plants, among others.
Upon realizing that the Lebanese and Middle East floristic richness represents an
untapped resource for the potential discovery of new therapeutic agents, I and other
researchers founded the AUB’s Nature Conservation Center for Sustainable Futures
(IBSAR) in 2002. Through my involvement with IBSAR, we were the first to decipher
the molecular mechanisms of action of the anticancer drug thymoquinone in colon cancer
and to identify a new molecule (Salograviolide A) from Centaurea ainetensis (Shawk Aldardar) with anticancer activities. Before our published work on this plant, there were no
research papers investigating its activity against cancer. In the future, I will continue my
efforts to pioneer research on the use of herbal extracts and herbal compounds for cancer
treatment. I will also sustain an active and well-funded research program to train
graduate students, inspire them, and promote excellence in individuals who would
hopefully shape a better world for us all.
The Zn chelator TPEN induces apoptosis in human colon cancer cells
Hazar Haidar1, Maamoun Fatfat1, Khaled Machaca2 and Hala Gali-Muhtasib1
1
Department of Biology, American University of Beirut, Lebanon, Department of
2
Physiology and Biophysics, Weill Cornell Medical College, Qatar
Zinc is an essential trace element with cofactor functions in a large number of proteins of
intermediary metabolism, hormone secretion pathways, immune defense mechanisms,
and as a cofactor of transcription factors it is also involved in the control of gene
expression. Our study demonstrates that treatment of the three colon cancer cell lines
(HCT116 p53+/+, p53-/- and p21-/-) with different concentrations of the cell permeable zinc
chelator, N, N, N’, N’ tetrakis (2-pyridylmethy)ethylenediamine (TPEN) resulted in
significant cell death. Viability of HCT116 cells was measured using the MTT assay after
exposure to TPEN and confirmed by the propidium iodide results showing cell death in
all three cell lines with differences in their sensitivity to TPEN treatment. Features of
apoptosis such as apoptotic bodies and nuclear fragmentation identified by Hoechst
staining accompanied the TPEN-induced cell death. TUNEL and Annexin assays were
also performed and confirmed the apoptotic effect of TPEN as well as the variation in the
drug response among the three cell lines. The antioxidant N-Acetyl-L-Cysteine inhibited
the cytotoxic effect of TPEN indicating that oxidative stress is the likely mediator of Zndeficiency-related cell death. Our results suggest that Zn2+ chelation by TPEN may be a
promising therapeutic approach against colon cancer. This project was supported by the
Qatar National Research Fund.
Keywords: Zinc chelator, TPEN, colon cancer, apoptosis
The flower-head infesting Tephritids in Lebanon
Khouzama Knio
Biology department, FAS, AUB
My research focuses on the biology and ecology of fruit flies belonging to the
Family Tephritidae. In 1995, I initiated a survey on the flower head infesting tephritids
associated with thistles in Lebanon and showed the existence of eighteen species that
were reared from twenty species of Lebanese thistles. Fifteen of these tephritid species
were reported to occur for the first time in Lebanon. Most of the tephritids had a narrow
host race. The few polyphagous species, that infested several host plants, showed high
intraspecific variations. This morphological diversity within the generalist species led to
the investigation of host race formation in fruit flies. Host race formation involves
morphological and biological adaptations of allochronically isolated populations to their
host plant. We have demonstrated this phenomenon in the highly oligophagous tephritid,
Chaetostomella cylindrica, and the oligophagous species, Terellia fuscicornis, and
Terellia serratulae.
Host Race Formation in Terellia serratulae
Stephanie G. Haddad, Colin A. Smith, and Khouzama M. Knio
Biology Department, American University of Beirut, Lebanon
Host race formation is a common phenomenon in tephritid flies involving morphological
and biological adaptations of allochronically isolated populations to their host plant. The
oligophagous fruit fly Terellia serratulae (Linnaeus 1758) is found at various locations in
Lebanon and at different elevations from May to October. It infests six thistles: Carduus
argentatus, Carduus pycnocephalus, Carduus arabicus, Cirsium phyllocephalum,
Cirsium lappaceum, and Cirsium acarna. The difference in phenology among its six
hosts suggests host race formation which necessitated a study to determine the extent of
morphological and genetic variation among its populations. A canonical discriminant
analysis performed using two head and four wing measurements showed that the different
populations of T. serratulae could be separated morphometrically where the individual
flies clustered into distinguishable groups, each representing a population associated with
a specific host plant. Ovipositor comparative studies showed that flies emerging from C.
acarna differed significantly from the rest in that they had morphologically distinct
ovipositors that were largest in length. Sequencing a 442bp mtND1 gene fragment in
different populations reared from different hosts at different elevations revealed 19 single
nucleotide polymorphisms (SNPs) and 9 haplotypes, whereas sequencing a 546bp
mtCOX1 gene fragment revealed 24 SNPs and 7 haplotypes. Haplotype sequences of
flies emerging from C. acarna showed a sequence divergence of over 3% for both COX1
and ND1 genes. This study provides morphometric and molecular evidence supporting
that the T. serratulae population associated with C. acarna most likely constitutes a
distinct host race.
The role of melanisation in defense against fungal infections
in the malaria vector Anopheles gambiae
Layla Kamareddine, Hassan Yassine and Mike Osta*
Biology Department, FAS, AUB. *Principle Investigator
Melanization is an immediate immune response in arthropods involving melanin
synthesis and its deposition on the surfaces of invading microorganisms leading to their
sequestration. It is also a prominent wound healing process manifested by the blackening
of the wound area in arthropods. Melanization is triggered by pattern recognition
receptors (PRRs) that upon binding pathogen associated molecular patterns (PAMPs)
activate a cascade of serine proteases culminating in the proteolytic cleavage and
conversion of the prophenoloxidase (PPO) zymogen into active phenoloxidase (PO). We
have previously reported that abolishing PO activity in the malaria vector A. gambiae, by
silencing CLIPA8, did not affect mosquito survival after infection with Escherichia coli
or Staphylococcus aureus {Schnitger, 2007 #304}. Both bacterial species were cleared
from CLIPA8-silenced mosquitoes as efficiently as from controls suggesting that
melanisation is not critical for anti-bacterial defense in the mosquito. In contrast, here we
report that the melanisation response in A. gambiae mosquitoes plays an important role in
defense against natural fungal infections.
Mutability of HK022 Nun protein reveals the requirements
for specificity and function
Caroline S. Tawk , Ingrid Ghattas, Colin A. Smith
Biology Department, FAS, AUB.
Lambdoid bacteriophage N-antitermination requires structurally similar binding of the
arginine-rich domains of N proteins to small, boxB hairpin RNAs. Phage HK022 Nun
protein competes with lambda N protein to bind lambda boxB and induces termination of
viral transcripts. N and Nun recognition of boxB appear structurally similar by NMR.
Though the lambda N-boxB interaction has been extensively examined, the recognition
of boxB by Nun requires understanding the basis of Nun-boxB specificity. In this study,
plasmid libraries expressing Nun with individually randomized codons in the argininerich domain were constructed, screened for ability to prevent lambda replication, and
assayed for activity using reporter system. Frequent functional mutants support the
neutral theory of molecular evolution. Immutable residues D26, R28, R32 and W33 were
identified in the 22-40 Nun binding domain. The binding requirement of these residues is
not revealed by the NMR model and it is different from N-boxB. The same Nun libraries
were cloned into N and tested for antitermination; mutability was different for some
residues in this context. Surprisingly, the four immutable mutants in Nun showed similar
restriction in N. The quantified activity of Nun mutants for Nun termination and N
antitermination suggests how recognition strategies evolve as well as improves the
proposed structural model.
Harvesting energy through thermoelectrics: Optimizing materials for power
generation and cooling
M. Kazan and M. Tabbal
Physics department , FAS, AUB
High efficiency thermoelectric materials are extremely needed for powergeneration-devices that are designed to convert waste heat into electrical power. Such
materials would play an important role in our current challenge to develop alternative
energy technologies to reduce our dependence on fossil fuels and reduce greenhouse gas
emission. In addition, the thermoelectric materials are extremely needed to be used in
solid-state refrigeration devices and microprocessors for better performing of the
electronic devices, and acceleration of the computational speed. The efficiency of
thermoelectric modules depends on the dimensionless thermoelectric figure of merit ZT,
which is a function of the Seebeck coefficient, electrical conductivity, thermal
conductivity and absolute temperature. Values of ZT=1 are considered good, and values
of at least in the 3-4 range are considered to be essential for thermoelectrics to compete
with electrical generation and refrigeration in efficiency. To date the best reported ZT
value is ~2.4. However, there are no theoretical limits to the possible values of ZT.
Certainly, theoretical guidance, in terms of thermal conductivity, Seebeck coefficient, and
electronic band structure and related properties are essential to identifying the most
promising thermoelectric materials and nanostructures. In the first stage of our research
program we optimize theoretically materials in bulk, thin films, superlattice, and
nanostructure forms characterized by very promising ZT values in a broad temperature
range. We understand and describe the various physical processes at the nanoscale level
which can further increase the ZT value. On the basis of the results obtained we will grow
the optimized materials and structures by plasma-assisted pulsed laser deposition method
which reported recently relevant experimental results showing the high potential of this
growth technique. In conclusion, the combination of advanced theoretical predictions,
efficient synthesis method and efficient measurement technique with a resolution on the
nanometer scale is expected to optimize new thermoelectric materials and nanostructures
suitable for the realization of new generation of thermoelectric devices for highefficiency energy saving by exploiting waste heat and refrigeration without moving parts
or the use of toxic gases.
Microstructural investigation of the oxidation of tungsten thin
films using remote plasmas
Al Mohtar, M. Kazan and M. Tabbal
Physics department, FAS, AUB
A low-pressure plasma system operating at microwave frequencies (2.45 GHz) in pure
oxygen has been developed to perform surface treatment of materials. The aim of this
work is to use this plasma reactor to induce the formation of the electro-chromic material
tungsten trioxide, WO3, starting from tungsten thin films. The experimental procedure is
to deposit pure and metallic tungsten thin films, with thicknesses ranging between 25 and
250 nm, using Pulsed Laser Deposition. The films are then exposed to the oxygen plasma
in order to induce oxidation of the films. The plasma has been characterized using
Langmuir probes and optical spectroscopy in order to determine ion densities and atomic
oxygen generation. A parametric study has been performed on the films as a function of
gas pressure, exposure time and substrate temperature, in order to determine the optimal
conditions for tungsten oxidation. A variety of materials characterization techniques, such
as X-Ray Diffraction, Rutherford Backscattering Spectrometry and Atomic Force
Microscopy have been used to study the properties of the synthesized material. Our
results show that operation of the plasma at low pressure (10 mTorr) and high power (400
W) for a duration of one hour with the substrate held at a temperature of 500 o C is
suitable in obtaining high quality WO3 thin films. An analysis and discussion of these
results will also be presented.
Infrared analysis and modeling of thin films
M. Shamseddine, M. Kazan and M. Tabbal
Physics department, FAS, AUB
Optical and electrical properties of semiconductor materials related to the recent
technological advancements that are playing a vital role in the integrated-circuit
manufacturing, optoelectronics, and countless industrial applications are often critical to
the functionality and performance of many devices. The combination of scientific interest
and technological impact calls for optical characterization methods as valuable in
characterizing optical properties.
Among the optical characterization techniques, Fourier Transform Infrared Reflectivity
FTIR is the most quantitative one in which simple theories can be used to analyze the
response of semiconductors to these infrared wavelengths as well as to the reflectivity
from layered systems. In addition, FTIR can probe even important intrinsic and extrinsic
semiconductor properties such as: lattice vibrations and phonon features, impurities
behavior and defects concentration, band characteristics, thickness, free carriers transport
as well as the geometry and interface behavior of microstructures on a layer-by-layer
basis.
For quantitative analysis, the reflectivity spectra of good quality thin films grown by a
typical PLD high vacuum system on commonly used substrates (silicon carbide SiC,
sapphire Al2O3) are fitted to a theoretical model for the reflectivity of unpolarized
infrared beam from anisotropic material. The developed model considers layer-by-layer
interface using the frequency dependent infrared dielectric function as given by the
damped Lorentz oscillator model (DLOM), in addition to the lattice and Plasmon
vibration contributions. The key development in our model is that the crystal anisotropy
as well as the interface condition has been taken into account. In addition to the
anharmonic vibrational properties of the host material, this model accounts for the crystal
point-defects, disorder, strain, and free carriers concentration and mobility through
classical and perturbation techniques.
The good agreement with the experimental results demonstrated that the proposed model
is a viable tool for the characterization of thin films. It’s a fast non-destructive tool that
provides an insight into the effect of growth conditions on the ordinary and extraordinary
physical properties of thin films. Besides, it brings very relevant information concerning
key parameters for technological applications namely, optical parameters, thermal and
electrical ones, mobility, doping level, thickness of the film, thermal conductivity,
crystallographic orientations and stresses at interface that reveal the crystalline of the
investigated samples. All these results make this model expensive for the semiconductor
industry.
Toward the remediation of accidental pollutions using advanced oxidation processes
coupled with smart on line monitoring analytical techniques
Antoine Ghauch
Chemistry department, FAS, AUB
Accidental pollution becomes one of the most important issues that several industrialized
countries are facing. Rapid solutions to a catastrophic scenario should be reliable and
easy to implement in order to avoid human damages and irreversible environmental
deterioration as well. The development of miniature analytical sensors able to provide the
local authorities with serious alerts is acknowledged as part of the solution. However,
those are not covering the majority of potential environmental contaminants. Emission
spectroscopy using imaging sensing systems equipped with engineered designed optical
fibres and sophisticated detectors can be used for the detection of abnormal
concentrations of conventional aqueous organic contaminants and emerging contaminants
e.g. pharmaceuticals as well. Once the alert is confirmed, an automatic water cleaning
process should be launched by releasing in-situ some remedial species like sodium
persulfate and zerovalent iron capable to reduce the concentration of contaminants for the
long-term without affecting the natural composition of water. An on-line monitoring of
the variation in the concentration of the contaminants probe allows therefore decision
makers to control a catastrophic scenario by minimizing its consequence on the
population and the environment as well.
Keywords: Advanced oxidation processes, zerovalent iron, water treatment, on line
monitoring devices, accidental pollution.
Ultrasonic/Fe0/H2O2 systems for the removal of sulfamethoxazole
antibiotic from water
Antoine Ghauch, Habib Baydoun, Peter Dermesropian
Chemistry department, FAS, AUB
In this study, water charged with sulfamethoxazole (SMX) was subjected to low
frequency ultrasonication at 20oC and pH 5 under H2O2 feeding in the presence of
nanometric (US/nFe0/H2O2 system) and/or micrometric (US/mFe0/H2O2 system) zero
valent iron particles. Removal rates of SMX from experiments of nanometric (synthetic
slurry material) and commercial micrometric iron particles have been compared under
different H2O2 additives and iron loads. Double distilled, carbonate-enriched double
distilled, tap and underground waters were used as different matrices for potential
decontamination applications in field. Results showed that SMX removal was positively
affected by the presence of carbonate species favoring iron corrosion that enhances H2O2
activation. Experiments showed also that nanometric iron particles were not efficient in
activating H2O2 while micrometric iron particles showed better efficiency in double
distilled water. This was ascribed to the increase in the nucleation sites at the proximity
of micrometric iron particle surface favoring the process of cavitations inception
increasing thereby the probability of formation of hydroxyl radicals. The developed
system showed clearly that advanced oxidation processes work better in a Fenton-like
process by heterogeneous catalysis in US/mFe0/H2O2 system instead of nanometric iron
slurry solution e.g. US/nFe0/H2O2 system.
Keywords: Sulfamethoxazole, ultrasonication, nanomertic iron, micrometric iron,
advanced oxidation processes.
Oxidation of bisoprolol in heated persulfate/H2O systems:
kinetics and products
Antoine Ghauch, Al Muthanna Tuqan
Chemistry department, FAS, AUB
The oxidative removal of dissolved aqueous bisoprolol fumarate (BIS), prescribed to treat
hypertension, by thermally activated sodium persulfate (Na2S2O8; SPS) was investigated
in a phosphate buffer solution at pH 7 and different temperatures. Several BIS/SPS ratios
were used in order to determine the reaction order with respect to SPS and BIS reagents
for reactions expanded over 60 min. The results showed that BIS disappearance was
pseudo-first order for 1-4 half-lives and the resulting rate constants-measured from 40 to
70oC – fit the Arrhenius equation, yielding apparent activation energy of 14.2 ± 1.3 kJ
mol-1. The observed aqueous phase BIS degradation half-lives ranged from 1.9 to 93.1
min. The effect of various inorganic additives on maintaining high stoichiometric
efficiency and SPS activation was studied. The results indicated that only HCO3- slightly
affected BIS degradation rate although full degradation was noticed at 60 oC. A test on
BIS spiked local mineral water showed full degradation of BIS after 1 h of reaction.
HPLC/MS analysis showed the presence of intermediate oxidized products. The high
stoichiometric efficiency obtained demonstrated that the use of BIS is a suitable
pharmaceutical probe for further investigations.
Keywords: Bisoprolol; persulfate; thermal activation; chemical oxidation, water
treatment.
Exploitation of fluorescence based techniques in understanding biophysical
processes, comprehending photonics of nanomaterials and developing optical
sensors
Digambara Patra
Chemistry department, FAS, AUB
Fluorescence techniques have been playing a pivotal role in chemistry, physics, biology,
medicine, nanotechnology and biotechnology due to its versatility, high selectivity,
sensitivity, simplicity and fastness. Using fluorescence as the major tool, we aspire to
understand the process of unfolding and refolding of protein molecules; fluidity,
dynamics and phase transition of artificial membranes; association and aggregation
process in micelle; kinetics and photochemistry of novel microcapsules, nanocrystals,
nanomaterials, organic molecules, metal complexes and encapsulated molecules. Our
motivation is further expanded to integrate our study in developing novel optical sensor
for various analytes of biological, industrial and environmental importance such as
protein, anti-oxidants, ammonia, pH, glucose etc, and fabricate a single molecule
fluorescence imaging set up to investigate photonics of individual molecules in films and
solution. Some of the present research results and future plan for next couple of years are
presented in this talk.
Keywords: Fluorescence; Membrane; Protein; Nanomaterials, Probe; Sensor; Photonics;
Spectroscopy.
Curcumin as a sensitive fluorescent molecular probe for investigating DPPC and
DMPC bilayer membrane properties
Elsy El Khoury, Rana M. Tafech, Digambara Patra*,
Chemistry department, FAS, AUB
1,7-bis(4-hydroxy-3-methoxyphenyl)-1,6-heptadiene-3,5-dione, popularly known as
curcumin, is extensively used as a spice, food preservative, colouring agent. It serves in
traditional medicine and cosmetics in many Asian Countries. Recently it is noted that
curcumin may find wide applications as a novel drug in the near future to control various
diseases, including inflammatory disorders, carcinogenesis and oxidative stress-induced
pathogenesis. In this study curcumin has been explored as a sensitive fluorescent
molecular probe to investigate lipid bilayer systems. Curcumin shows solvatochromic
behaviour in various solvents. The partition coefficients of curcumin with phospholipids
such as dipalmitoylphosphatidylcholine (DPPC) and dimyristoylphosphatidylcholine
(DMPC) in the gel as well as sol phase have been estimated. The phase transition
temperature of phospholipids from gel to sol phase could be determined by modulating
fluorescence intensity of curcumin. The effect of cholesterol on phase transition
temperature and the role of ionic liquid in lipid membrane have been explored using
fluorescence probing method. The same technique is applied to inspect the interdigitation
of lipid bilayer by hydrogen peroxide.
Keywords: Curcumin; Fluorescence Probing; Membrane; DMPC; DPPC; Cholesterol;
Ionic Liquid; Hydrogen Peroxide.
The atmospheric and analytic laboratory (AAL)
Najat Aoun Saliba
Chemistry department, FAS, AUB
The scientific knowledge established at the Atmospheric and Analytic Laboratory (AAL)
is meant to serve the environmental community in Lebanon and the region. At the
atmospheric level, our work focuses on determining aerosol concentrations and their
chemical composition in polluted atmospheres, assess their sources and sinks, and
understand their atmospheric transformations. Our work, also, involves the speciation of
smoke emitted from narghile: a local, highly popular and traditional smoking tool, and
the understanding of their sources, their mechanisms of formation in tobacco pyrolysis
and their stability and fates. At the analytical level, AAL uses the state of the art
analytical techniques to isolate and identify potent anti-cancer and anti-inflammation
agents and thereby validate endemic knowledge on medicinal terrestrial and marine
organisms.
In brief, we are here to sniff alien emissions into the air and if the smell gets concentrated
due, for example, to tobacco smoke, we would be there to look into aerosol formation,
dilution, content, adsorption, absorption, deposition and re-evaporation from our hair,
clothes, surrounding surfaces of walls, glass, sofas, chairs, and others. However, when
the smell gains an aromatic flavor from herbs, trees, fruits, and marine habitats, we would
be curious to investigate the molecular structure of its causes.
Which one kills you faster? Cigarette or arghile?
Elizabeth Sepetdjian
Chemistry department, FAS, AUB
To answer this question arghile smoke samples were prepared in the aerosol lab, and
chemical analysis were done to the particle and gas phase of the smoke according to
certified methods (EPA, Canada Health, coresta) applied for cigarette smoke. Although
the same toxins were analyzed in the two types of smoking, analytical methods for
arghile smoke were optimized because of the major differences between arghile and
cigarette smoking in terms of tobacco combustion, smoking duration, tobacco amount,
presence of charcoal and amount of TPM.
Arghile smoke components were analyzed both in mainstream and sidestream smoke for
a standard arghile session, such as CO, nicotine, PAH, aldehydes, HCN, phenols and
nitrosamines. Also optimized analytical methods were applied on cigarette smoke
samples as control. Quantification of the chemicals was done using calibration standards,
internal standards; also the recovery, precision and detection limits were assessed for
each analyte.
Recently, chemical analysis were done for arghile topography samples that have realistic
puff parameters (number ,volume, duration…) recorded in VCU (Virginia
Commonwealth University), also a comparison between smoking maasal tobacco,
placebo tobacco and cigarette was performed in terms of nicotine, CO, aldehydes and
PAH.
Identifying the Chemical Marker Differentiating Water Pipe Smoke from Cigarette
Smoke.
Nadine Abdallah
AAL- Atmospheric and Analytical Chemistry Lab. Chemistry department, FAS, AUB
In recent years, the Narghile (Water Pipe) has become an increasingly popular smoking
method among populations worldwide. In comparison to cigarettes, which have had
decades of research dedicated to their scientific study and analysis, very little is known
about the exact composition of Water Pipe Smoke (WPS) and its possible effects on
human health. In this study, a comprehensive analytical investigation is conducted with
the aim of isolating a discernable chemical marker in WPS in contrast to the known
chemicals that compose cigarette smoke.
Using a smoking machine designed and operated by the aerosol lab in the Department of
Mechanical Engineering at AUB, cigarette and water pipe smoke were collected on
different glass fiber filters. An extraction and fractioning process followed. The
identification and analysis of the final extraction products was done using Gas
Chromatography and Mass Spectrometry (GCMS). While several compounds were found
to be similar, we were successful to isolate markers for WPS.
The Highway is Our Airway
Qassem Al-Asaad
AAL- Atmospheric and Analytical Chemistry Lab. Chemistry department, FAS, AUB
Continuous measurements of number size distribution of fine (0.25≤Dp<1μm) and coarse
(1≤d≤31μm) particles are performed at AUB and on the road connecting Beirut to North
Lebanon, from February up until today. The effects of particles on human health are of
greatest concern in urban areas. Epidemiological studies showed relationships between
fine particle concentration and respiratory and cardiovascular diseases. Our work focuses
on understanding the environmental effects of atmospheric particles based on measuring
particle number size distributions. Using a particle counter that measures up to 31
different particle channels, we measure on daily basis the particle distribution on road
during rush hours and contrast it with measurements conducted at AUB. Interesting
results and significant differences between the road and the background site at AUB were
observed.
Absorbed Residue Analysis of the Beirut Amphora
Marshall Woodworth
History and archaeology department, AAL- Atmospheric and Analytical Chemistry Lab.
Chemistry department, FAS, AUB.
Amphorae are transport containers that were used during antiquity for long-distance,
seaborne trade. While the general types of goods transported in this group of vessels has
been established, the original content of specific classes of amphorae is still poorly
understood. In order to improve our understanding of inter-regional economics during
antiquity, the determination of what goods were being traded to where (i.e. the original
content of amphorae) is necessary.
Chromatographic methods, most notably that of Gas Chromatography (GC) coupled with
Mass Spectrometry (MS), allow for the molecular-level identification of complex organic
samples and are the analytical methods of choice in organic residue analysis. Current
GC/MS methodologies have proven successful in analyzing organic residue absorbed in
the bodies of ceramic vessels. The initial process involves testing for tartaric acid as an
indicator of wine (as well as other carboxylic acids specific to grape and/or fermented
products). A subsequent round will focus on lipid analysis.
It is generally believed that the “Beirut amphora” contained wine, the purpose of this
project is to establish this empirically. At present, the preliminary results have been
completed for the 'wine biomarker' round of analysis.
POSTERS
Autism susceptibility genes in the Lebanese population.
Soueid J.1, Ghanem S.1, Boustany R-M1-3.
1
Neurogenetics Program and Division of Pediatric Neurology, Departments of Pediatrics
and Biochemistry, 2Departements of Pathology and Laboratory Medicine, American
University of Beirut Medical Center, Beirut, Lebanon, 3Departments of Pediatrics and
Neurobiology, Duke University Medical Center, Durham, NC, USA
Autism is a neurodevelopmental disorder characterized by three core symptom domains:
ritualistic-repetitive behaviors, impaired social interaction, and impaired communication and
language development. Although patients with autism share a core set of symptoms, the
underlying genetics are varied and poorly understood. Recent studies have highlighted
etiologically relevant recurrent copy number changes in autism, such as 16p11.2 deletions and
duplications, as well as the involvement of many candidate genes such as PTEN, SHANK, and
NLGN4, many of which involve the neuronal synapse. Our aim is to either confirm previously
identified loci or uncover novel autism susceptibility genes in the Lebanese population. Thus, we
are using Affymetrix 250K NspI GeneChip Microarray and Cytogenetics 2.7M Microarray
technology to detect microdeletions and duplications in a subset of Lebanese autistic children,
and to map homozygous regions in each family. The Lebanese population is ideal for
homozygosity mapping because of its high rate of shared ancestors and number of siblings per
family. Our preliminary results implicate genes previously identified as autism, schizophrenia and
mental disorders susceptibility genes. These are PLXNA4, CACNA1C, CSMD3. We also
detected using homozygosity mapping in one family a homozygous region only in affected
siblings encompassing the VPS13B gene (also known as COH1 gene) associated with Cohen
syndrome, a disorder with autistic features. More interestingly, several of the deletions and
duplications include new candidate genes for autism such as Gephyrin (GPHN) which has a role
in GABA receptor clustering, Interleukin 3 (IL-3) coding a cytokine with neurotrophic activity,
Protein Tyrosine Phosphate Receptor type T (PTPRT) involved in synapses, and thus are
candidates for involvement with learning. These preliminary results highlight the effectiveness of
homozygosity mapping in searching for susceptibility and candidate genes associated with
autism. We are screening a larger number of families, and will validate results with other
techniques like PCR and sequencing.
Exogenous Galactosylceramide Corrects Growth and Apoptotic
Defects in Human CLN3-Deficient Cells and Behavioral Deficits in
CLN3Δex7/8 Knock-in Male Mice by Lowering Ceramide
El Chebib H, Harati H, Noutsi B, ElMaoued A, Cotman S and
Boustany R-M
Neurogenetics Program/Department of Pediatrics departments.
Juvenile neuronal ceroid lipofuscinosis (JNCL) is an inherited neurodegenerative
disorder manifesting as vision loss, seizures, cognitive and motor decline and premature
death in the second to third decade. The wild type (WT) CLN3 gene is antiapoptotic with
mutations resulting in negative modulation of cell growth and increased apoptosis. CLN3
protein (CLN3p) localizes to Golgi, endosomes and lipid rafts (LRs), and harbors a
galactosylceramide (GalCer) LR-binding domain. There is evidence it may be a
transporter for GalCer from Golgi to LRs. GalCer and CLN3p are diminished in LRs
derived from JNCL-derived cells. After transfection with WT-CLN3, GalCer is restored
to LRs, and growth and apoptosis are corrected. Negative modulation of growth and
increased apoptosis was achieved with siRNA knockdown of the enzyme catalyzing
GalCer synthesis, GalCer synthase, in lymphoblasts. CLN3 siRNA knockdown of human
lymphoblasts resulted in diminished proliferation and increased apoptosis. Growth and
apoptosis rates were corrected after addition of GalCer to both CLN3-deficient and
GalCer-deficient cells. Total ceramide was increased in siRNA knocked-out CLN3 cells
and addition of GalCer normalized ceramide. GalCer is significantly higher than control
in brains of CLN3Δex7/8 mice after intravenous injections of GalCer. Astrocytosis in
CLN3Δex7/8 mice brain was significantly higher compared to normal controls. This was
normalized after GalCer intravenous injections. CLN3Δex7/8 mice exhibit behavioral
changes and shortened life span. CLN3Δex7/8 mice injected with GalCer performed
significantly better in the rotarod and pole climbing tests than both normal controls and
vehicle injected CLN3Δex7/8 mice. This work suggests that mutant CLN3-dependent
lowering of GalCer contributes to neuronal loss in JNCL via increased ceramide and that
GalCer supplementation may lower ceramide halting cell death and ensuing
neurodegeneration. In conclusion, these results show that GalCer supplementation
lowered the pro-apoptotic ceramide and positively affected the behavior of CLN3Δex7/8
mice, laying the groundwork for possible future human application.
CLN3 expression in breast cancer
Noutsi P1, Raad M, Farran B1, El Khoury M1, Boulos F2, Zaatari G2, Boustany R-M1,3
1
Neurogenetics Program and Division of Pediatric Neurology, Departments of Pediatrics
and Biochemistry, American University of Beirut, 2Department of Pathology, American
University of Beirut Medical Center, Beirut, Lebanon, 3Departments of Pediatrics and
Neurobiology, Duke University Medical Center, Durham, NC, USA
CLN3 is an anti-apoptotic gene and when defective causes Juvenile Neuronal Ceroid
Lipofuscinosis. It is an autosomal recessively inherited neurodegenerative disease.
Rylova et al., have shown the overexpression of CLN3 at the RNA and protein level in
ovarian cancer, breast carcinoma cell lines, and in solid human colon cancer (1). The
work focuses on invasive ductal carcinoma (IDC), the most common type of sporadic
breast cancer. Breast Cancer accounts for more than a third of all cancers diagnosed in
Lebanon every year and is more aggressive relative to the US or Europe.
Overexpression of an antiapoptotic gene, like CLN3, could aggravate the grade of the
tumor resulting in a worse prognosis or faster progression. A goal is to determine whether
CLN3p is overexpressed in IDC patients in Lebanese breast cancer patients and to
delineate the underlying mechanism. This overexpression may be attributed to loss of
tumor suppressor genes. Other mechanisms might be hypomethylation of the CLN3
promoter (3). Q RT-PCR was performed to study CLN3 expression in 45 IDC cases of
grades I, II and III. A methylation assay established the percentage of methylation in the
CLN3 promoter region in normal tissue versus breast cancer. Cytogenetics assays using
2.7M cytochips were performed on 2 FFPE cases. Early analysis showed several gains
and losses covering genes related to apoptosis such as TAOK2 and DNA repair
mechanisms e.g ERCC4 (restriction endonuclease). A gain of a ras related oncogene
RAB26 was detected. Q RT-PCR results show that CLN3 is overexpressed in 82.4%,
60% and 58.3% of grade III, II and I cases respectively. Its promoter region is
hypomethylated in some but not all breast cancer samples relative to normal controls. Our
research may lead to establishment of CLN3 as a biomarker of breast cancer, its
progression or be developed as a therapeutic target.
References:
1. Rylova SN, Amalfitano A, Persaud-Sawin DA, Guo WX, Chang J, Jansen PJ. The
CLN3 gene is a novel molecular target for cancer drug discovery. Cancer Res. 2002;
62(3): 801-808.
2. Stange DE, Radlwimmer B, Schubert F, Traub F, Pich A, Toedt G. High-resolution
genomic profiling reveals association of chromosomal aberrations on 1q and 16p with
histologic and genetic subgroups of invasive breast cancer. Clin Cancer Res. 2006;
12(2):345-352.
3. Kristensen LS, Nielsen HM, Hansen LL. Epigenetics and cancer treatment. Eur J
Pharmacol. 2009; 625(1-3):131-142.
Keywords: Breast cancer, juvenile neuronal ceroid lipofuscinosis, CLN3, methylation,
invasive ductal carcinoma
Use of chromosomal microarray analysis in the diagnosis of neurogenetic disorders
in Lebanon
Ghanem S1, Dabbagh O2, Boustany R-M1-3, and Farra C4.
1
Neurogenetics Program and Division of Pediatric Neurology, Departments of Pediatrics
and Biochemistry, American University of Beirut, Beirut, Lebanon
2
Departments of Pediatrics and Adolescent Medicine, American University of Beirut
Medical Center, Beirut, Lebanon
3
Departments of Pediatrics and Neurobiology, Duke University Medical Center, Durham,
NC, USA
4
Departements of Pathology and Laboratory Medicine, American University of Beirut
Medical Center, Beirut, Lebanon
Microarrays have greatly improved the detection of microdeletions and/or
microduplications in patients with abnormal clinical phenotypes and normal karyotypes.
In this study and for the first time, Affymetrix Cytogenetics 2.7 M arrays were performed
on a sample of Lebanese children. This chip has unique, non polymorphic probes
covering the whole genome for detection of copy number variation (CNV) and loss of
heterozygosity (LOH). In this study, nineteen patients have so far been referred for
microarray analysis. Of these, six had developmental delay, three had dysmorphic
features, three had muscular weakness, five had mental retardation, one had myoclonic
ataxic disorder, and one had psychomotor delay. Genomic DNA was extracted from 2 ml
of peripheral blood then fragmented, labeled and hybridized. Analysis using Chas
software showed possible CNVs and LOH. One patient with developmental delay and
another with muscular weakness showed no pathogenic CNV. Apart from CNVs, LOH
was present for numerous chromosomal regions reflecting parental consanguinity or
shared ancestry. In the remaining 17 cases (approximately 90%), abnormalities were
found. Certain cases had few regions of genomic imbalances that overlapped with
reported CNVs indicating no known clinical significance, while others were interpreted
as having unknown clinical significance. Some of these CNVs encompass known
pathogenic genes and others encompass putative genes. One patient showed
microduplications that were not present in parental DNA indicating de novo CNVs. The
genes were on chromosomes 2 and 20 covering genes HOXD4, HOXD13, HOXD10, and
JAG1. Microarray analysis by cytogenetics 2.7 M arrays has become a powerful tool in
identifying candidate genes in the etiology of disorders. Many abnormal phenotypes may
be a result of submicroscopic CNVs of gene(s) that conventional cytogenetic studies are
unable to detect. Thus, Cytogenetics 2.7 M arrays represent an interesting diagnostic tool
uncovering genetic abnormalities previously impossible to ascertain.
Inhibitory effects of arsenic trioxide and interferon alpha on the proliferation of
chronic myeloid leukemia cell lines and fresh CML cells, supported by in vivo
preliminary results
Saliba Jessica, Iskandarani Ahmad1, El Eit Rabab1, De The Hugues2, Bazarbachi Ali1,
Nasr Rihab1
1
Department of Anatomy, Cell Biology and Physiological Sciences, American University
of Beirut, Beirut, Lebanon
2
Université de Paris 7/CNRS UMR 7151, Hôpital St. Louis, Paris, France
Imatinib is currently the standard of care in the treatment of chronic myeloid leukemia
(CML) patients. However, imatinib is not curative since most patients who discontinue
therapy will relapse. Interferon alpha (IFN) induces hematologic and cytogenetic
remissions and interestingly, prior exposure to IFN allowed imatinib discontinuation in
some CML patients. Arsenic trioxide (As) inhibits the proliferation of BCR-ABLexpressing cells.
We have investigated the effects of the combination of As/IFN on the proliferation of
CML cell lines. We found that IFN alone had minimal effect. Arsenic alone significantly
decreased their proliferation in a time and dose-dependent manner. Interestingly, the
addition of IFN to arsenic was synergistic in AR230 and additive in K562. This
synergistic effect between IFN and arsenic was accompanied by dose-dependent
apoptosis as evidenced by TUNEL positivity and caspase activation. Colony-forming
assay was performed on bone marrow and CD34+ cells collected from CML patient.
Interestingly, arsenic and IFN produced a synergistic decrease in myeloid colony
formation, especially when compared to Imatinib. Preliminary results of an in vivo study
of a murine CML model showed prolonged survival of leukemic mice when treated with
the combination of As/IFN, as compared to untreated controls or to mice treated with
each drug separately.
These results suggest that arsenic and IFN synergize to inhibit proliferation and induce
apoptosis in CML cells, thus providing a rationale for their combined use in the treatment
of CML in the future, to target dormant CML stem cells that are spared by imatinib.
Zinc chelators as anticancer agents
Maamoun Fatfat1, Hazar Haidar1, Khaled Machaca2 and Hala Gali-Muhtasib1
1
Department of Biology, American University of Beirut, Lebanon, 2Department of
Physiology and Biophysics, Weill Cornell Medical College, Qatar
Zinc is a versatile element that has important regulatory roles and acts as a cofactor for
hundreds of enzymes. Recent evidence indicates that Zn2+ chelators are promising
anticancer agents.
One of the most widely used transition metal chelators is the cell permeable high affinity
intracellular Zn2+ chelator TPEN in addition to the cell membrane impermeable and
extracellular Zn2+chelator DTPA. Both compounds were found to result in the death of
many cancer cell types, although TPEN is a more efficient Zn2+ chelator than DTPA. In
this study, the anti-neoplastic effects of TPEN and DTPA were evaluated in three human
colon cancer HCT116 cell lines (p53+/+, p53-/- and p21-/-). Treatment of colon cancer cells
with TPEN resulted in significant cell death at concentrations much lower than those
used for DTPA (IC50= 3.5μM TPEN vs 250μM DTPA). This noticed difference in time
and dose response among both drugs could be attributed to the mechanism of DTPA’s
action as an extracellular chelator of Zn whilst it cannot chelate intracellular Zn as TPEN.
Cell cycle progression analysis using flow cytometry and cell with PI staining showed an
increase in cell death that was much more significant in cells treated with TPEN than
those with DTPA. To make sure that the cell death induced by TPEN treatment was due
to apoptosis, Hoechst nuclear staining was performed and apoptotic characteristics were
observed in the treated cells, which was further confirmed by TUNEL and ANNEXIN
assays. Apoptosis by TPEN was completely prevented by exogenous addition of ZnSO4
or by the pretreatment with the antioxidant compound N-acetylcysteine (NAC). Our
results suggest that Zn2+ chelation is a promising approach in colon cancer therapy. This
project was supported by the Qatar National Research Fund.
Keywords: Zinc chelator, TPEN, colon cancer, ROS, apoptosis
The role of the Retinoblastoma protein, pRb, during adult neurogenesis in the
olfactory bulb
Naser Rayan1, Vandenbosch Renaud2, Al Lafi Sawsan1, Slack S. Ruth2 and Ghanem
Noël1*
1
2
Department of Biology, American University of Beirut, Lebanon
Department of Cellular and Molecular Medicine, University of Ottawa, Ontario, Canada
*Corresponding author
The retinoblastoma protein, pRb, is a tumour suppressor gene that plays a critical role in
the control of cell proliferation and differentiation during development. However, Rb’s
function in the adult brain remains unknown and Rb conditional knockout mice in the
telencephalon die at birth. To uncover Rb’s role in the adult brain, we generated an
inducible Rb deletion specifically in stem cells and progenitor cells by crossing the
Nestin-Cre ERT2; YFP/YFP reporter mice with Rb floxed/floxed mice. In this system,
upon tamoxifen administration, Cre translocates into the nucleus to delete Rb and activate
the expression of the yellow fluorescent protein, YFP. 5-6 weeks old mice were injected
with tamoxifen and sacrificed 2 or 4 weeks later. We then assessed neurogenesis in the
adult subventricular zone (SVZ) and the olfactory bulb (OB) in Rb mutant versus control
animals. Using BrdU labelling, we show that Rb deletion leads to: 1) increased
progenitor proliferation in the SVZ and the rostral migratory stream (RMS); 2) more
neuroblasts migrating to the olfactory bulb as indicated by the presence of more YFP+
granule cells in the mutant OB. Since most GABAergic neurons in the OB are derived
from SVZ progenitors, we analyzed the distribution of the distinct GABAergic subtypes
in the bulb and detected an increase in Calretinin-expressing interneurons (CR) but not
Calbidin- (CB) or Tyrosine hydroxylase-positive interneurons (TH) in the absence of Rb.
Our data indicates that Rb is required for the proliferation and specification of specific
subtypes of inhibitory neurons in the brain.
Synthesis of tungsten trioxide by PLD for electrochromic devices
E.Bacha, A. Al Mohtar, M.Tabbal
Physics department, FAS, AUB
Tungsten trioxide (WO3) has attracted attention due to the optical properties when
applying a voltage. For that it is extensively used in electrochromic devices that permit to
a transparent window to be colored under a specific DC current. Nowadays,
electrochromic devices could be obtained by several materials such as polymers but the
most important electroactive layer are the metal oxides especially WO3 [1]. The
difference between the transparent and colored form is related to the oxidation and
reduction form of the material. In the case of WO3, the W6+ oxidation form provides the
transparency whereas the W5+ (MxWO3) reduction form provides the coloration which is
deep blue [2].
Our work is based on the elaboration of a tungsten oxide electrochromic device where
tungsten thin film is prepared by PLD (pulsed laser deposition) on ITO (indium tin oxide)
coated glass than oxidized in order to obtain WO3 thin film. The construction of this
device is based on three elements: ITO|WO3|LiClO4|counter electrode|ITO. The latest
could be an electrochromic layer or a conductive electrode like platinum. The
microstructure, the grain size and the thickness of the WO3 film affects directly the
optical properties. Therefore our study is first based on the optimization of the structural
properties of the tungsten trioxide thin film on ITO transparent foil.
[1] R. Baetens, B.P. Jelle, A. Gustavsen, Solar Energy Materials & Solar Cells, 94, 87-105, 2010.
[2] Y. Suda, H. Kawasaki, T. Oshima, Y. Yagyuu, Thin solid film, 516, 4397-4401, 2008.