Annotated Bibliography
Danielle Hunter
Mentor: Dr. Susan Hutson
Brainum J. Branching Out for More Muscle. Iron Man Magazine 2008.
The purpose of this article is to explain what research has been done on branched chain amino
acid (BCAA) supplements. The outcome of the article was to make your own decision about
whether taking a BCAA supplement is beneficial or not based on the situation. The article
discussed many studies done about BCAA, such as that a lack of leucine can lead to decreased
abdominal fat and liver fat. Brainum advises not to do it, because death is a result of removing
leucine from the diet. An issue with the article is that many studies are discussed, but none of
them are cited in text. There is a list of citations at the end, but the citations should be cited within
the text. Brainum is a nutrition consultant, but is not accredited in any field even though he has
written hundreds of researched-based articles. Even though it is in Iron Man Magazine, there
should be an author that is recognized in the field in order to give valid data. There is also a
limited audience due to the title of the magazine. The article is targeted towards body builders
and others interested in gaining more muscle. If the article was in a different magazine, more
people could potentially read the article and learn more about branched chain amino acids.
Shaughnessy S, Smith ER, Kodukula S, Storch J, Fried SK. Adipocyte metabolism in adipocyte
fatty acid binding protein knockout mice (aP2-/-) after short-term high-fat feeding: functional
compensation by the keratinocyte [correction of keritinocyte] fatty acid binding protein. Diabetes.
Jun 2000;49(6):904-911.
The adipocyte fatty acid binding protein (AFABP) knockout mouse was compared to the
wildtype on a high-fat diet since it was previously found that the knockout increased expression
of the kerationocyte fatty acid binding protein (KFABP). Fat metabolism was the main focus by
doing lipolysis, which involves preparing adipocytes and incubating them to determine the
glycerol level. It was found that basal lipolysis was similar between the two mice and
norepinephrine stimulated lipolysis was actually lower on the high-fat diet as compared to the
low-fat dieted mice. Overall, it was found that KFABP can make up for the lack of AFABP. One
of the authors, Fried, is highly well-known and respected in this field and therefore makes the
journal article accepted. Her main interest of research is obesity and adipose tissue biology. Even
though this topic has a limited audience, it has been cited 53 times in 10 years. The main reason it
is cited is due to the protocols used, since adipocyte isolation has become an important aspect of
fat metabolism research, which was mostly developed by Fried.
She P, Reid TM, Bronson SK, Vary TC, Hajnal A, Lynch CJ, Hutson SM. Disruption of BCATm
in mice leads to increased energy expenditure associated with the activation of a futile protein
turnover cycle. Cell Metab. Sep 2007;6(3):181-194.
The journal article looks at the three types of the BCATm mouse. The wildtype (wt) has the
enzyme BCATm, whereas the knockout (KO) does not have the enzyme BCATm. The
heterozygous mouse has some of the BCATm gene as well. It focuses on the reason for the
knockout mouse having a lower weight as compared to the wildtype. The study describes other
studies that have previously discovered that protein intake can affect energy outtake positively.
Due to this, the study looks at ways that the knockout mouse can affect energy by putting mice on
a high-fat diet to see the outcome since the wildtype mouse has previously weighed significantly
more than the knockout. The wildtype mouse was about 12 g higher in weight than the knockout
as well as the knockout consuming more food than the wildtype. This suggests that that knockout
has the ability to increase energy expenditure. There was not a final determination about how or
why the knockout mouse can do this. Protein metabolism was examined, but fat metabolism was
not. The study’s final observation was that a high protein turnover rate is the factor that causes the
knockout to be leaner. Since decreased fat was found in the knockout, the study should have
looked at fat metabolism to see what the difference was between the wildtype and the knockout.
This article has been cited 28 times, which is a reasonable amount considering this is a very
specific field. Pengxiang has not been in many publications, but has done extensive research in
this field. Another author, Hutson, is also very well-versed in the BCATm protein and has been in
a large number of publications and has spoke at a lot of conferences. The results of the article can
help others determine how branched chain amino acids can help fight obesity in the future.
She P, Van Horn C, Reid T, Hutson SM, Cooney RN, Lynch CJ. Obesity-related elevations in
plasma leucine are associated with alterations in enzymes involved in branched-chain amino acid
metabolism. Am J Physiol Endocrinol Metab. Dec 2007;293(6):E1552-1563.
The study investigates the enzymes in branched chain amino acid (BCAA) metabolism to see if
they are modified in obesity. The first two steps in BCAA were examined, BCATm,
mitrochondrial branched chain amino acid aminotransferase and BCKD, branched chain a-keto
acid dehydrogenase. Two models were used for this study, both mice and Zucker rats. The article
discusses that adult rodents do not have the BCATm enzyme in the liver, but BCKD is believed
to be in the highest concentration in the liver. In high-fat diet-induced obesity in mice, there were
high plasma BCAA levels in both mice and rats. Overall, alterations in BCAA metabolism can
potentially be a factor in high plasma BCAA levels. This in turn can increase protein synthesis in
order to protect protein loss. This article has been cited 17 times in the past 3 years. Again, this
article has a specific audience, but more research is being done on the branched chain amino
acids, especially leucine. This article can provide others with information about BCAA
metabolism to further research in the future dealing with obesity.
Metabolism and clinical implications of branched chain amino and ketoacids : proceedings of the
International Symposium on Metabolism and Clinical Implications of Branched Chain Amino
and Ketoacids, held at the Kiawah Island Conference Center, Charleston, South Carolina, U.S.A.,
November 15-16, 1980 / editors, Mackenzie Walser and John R. Williamson.
This study concentrates on leucine metabolism in a fed and fasted state. In a fasted rat’s muscle
leucine can potentially spare glucose. The study claims that leucine is the only branched chain
amino acid to do, but it did not explain why or give previous evidence. In order to determine if
BCAA can stimulate the production of glutamine and alanine, the levels were looked at in
isolated skeletal muscle. Alanine was more of the focus as compared to glutamine, even though it
was thought that glutamine was more of an important form. It was not described why glutamine
was the more important form, or why alanine was looked at more closely. Throughout the study,
there are many discussions about further research that needs to be done on different topics that
were discussed briefly. Even though this is from 1981 and more research needed to be done on
the topic, the study was not as thorough as it should have been. There was also discussion about
the regulation of leucine metabolism in adipose tissue since leucine was thought to be the only
amino acid to be metabolism in the muscle. At one point, the study claims they did “extensive”
studies, but does not describe what these studies are. This happens throughout the paper, and
many times the study is not explained in detail. Goldberg has been published with numerous
articles, most of which have been cited a couple hundred times. This shows that his research was
the basis of more research in the future.