By Kristie Stoick, M.P.H., and John J. Pippin, M.D.
Alternatives to Animal Research
 Chimp Genome Project
Shows Tiny Difference Makes All the Difference
Employing the results of the recently completed Chimp Genome Sequencing
Project, researchers at the University of California San Diego
have linked human-chimp genetic differences to two important
species-specific disease findings. One is the discovery of the
first human-specific protein that is also expressed in brain
cells associated with human brain diseases that do not occur
in chimps, such as Alzheimer’s disease, multiple sclerosis,
and HIV-related dementia. The second is a single oxygen atom
difference that makes humans and chimpanzees resistant to each
other’s malarial parasites.
Says Ajit Varki, M.D., coauthor
of both studies, “Chimpanzees
have long been thought of as a model for studying human diseases. In fact,
what is most remarkable is that many of our diseases are rather different,
either in incidence or in severity.” If a single oxygen atom difference
can convey malaria resistance, it’s small wonder that chimp research
is such a poor surrogate for human studies.
Hayakawa T, Angata T, Lewis AL, et al. A human-specific gene in
microglia. Science. 2005;309:1693.
Martin MJ, Rayner JC, Gagneux P, et al. Evolution of human-chimpanzee
differences in malaria susceptibility: relationship to human genetic
loss of N-glycolylneuraminic acid. PNAS. 2005;102:12819-12824.
New Cells Allow Cruelty-Free Drug Testing
St. Paul, Minn.-based biotechnology company BioE has become the
first company to produce and market multilineage progenitor cells
(MLPCs) from human cord blood. These stem cells are isolated
from umbilical cord blood after birth, and scientists can coax
the cells into at least nine different cell types: fat cells,
three different types of nerve cells, liver and pancreas precursor
cells (which could then be differentiated into hepatic or pancreatic
cells), muscle cells, blood vessel wall cells, and bone cells.
Drug and chemical companies can use these progenitor cells, and
their derived descendant cells, to test the metabolism and toxicity
of new compounds in the species of interest—humans. Researchers
can gain a better knowledge of the biochemical and genetic characteristics
of human cells—which is important for cancer and other
disease research—and develop potential tissue and gene
therapies for diseases that attack these organs.
Interested researchers can find out more at www.bioe.com.
 Fewer Dogs and Cats Used in Experiments
Since 1973, the number of dogs, hamsters, cats, guinea pigs, and
rabbits used in experiments has decreased by at least 40 percent,
according to the recently released 2004 USDA Animal Care Report.
But the number of primates used has increased by 30 percent—up
to 54,998—as has the number of farm animals, up 58 percent
since 1990, when use of these animals was first reported.
The
report did not include figures on rats, mice, birds, or reptiles—who
are involved in 95 percent to 99 percent of experiments but are
not counted by the USDA or covered by the Animal Welfare Act. Recent
reports estimate the number of rats and mice used in laboratories
at 80 million to 100 million, and that figure is increasing every
year.
USDA Animal Care Report Fiscal Year 2004. APHIS Web
site. Available at: http://www.aphis.usda.gov/ac/awreports/awreport2004.pdf.
Accessed Feb. 24, 2006.
Carbone, L. What Animals Want. New York, NY: Oxford University
Press; 2004:25-28.
By Dulcie Ward, R.D., and Susan Levin, M.S., R.D.
Bone Health
 Calcium Supplements Don’t Reduce Fracture
Risk
Calcium and vitamin D supplementation did not significantly reduce
the incidence of fractures in a recent study. The 36,282 postmenopausal
participants enrolled in the Women’s Health Initiative
clinical trial were given either a supplement containing 500
milligrams of calcium plus 200 IU vitamin D or a placebo daily.
Hip fractures were 12 percent less frequent in the supplemented
group, but that result was considered to have been attributable
to chance. The supplemented group had no reduction in vertebral
fracture, fracture of the lower arm or wrist, or total fractures.
There was also a 17 percent increase in kidney stone formation
among the supplemented group. The results reinforce earlier studies
showing that increased calcium intake does not necessarily mean
stronger bones and better health. Other factors that seem to
play a more important role in bone health include sodium intake,
smoking, physical activity, and intake of animal protein, which
leaches calcium from the bones.
Jackson RD, LaCroix AZ, Gass M, Wallace RB, Robbins J, Lewis CE,
et al. Calcium plus vitamin D supplementation and the risk of fractures. N
Engl J Med. 2006;354:669-683.
Weight Loss
Dairy Products Fail to Stop Weight Gain
A new study from Harvard’s Health Professionals Follow-up
Study gives no support to the advertising claim that milk helps
control weight. In a group of 51,529 men ages 40 to 75, those who
consumed the most calcium or dairy products at the study’s
onset gained the same amount of weight as those who consumed the
least.
 In an unadjusted analysis, men who increased their calcium
or dairy intake during the study seemed to gain slightly less weight
(approximately a 1-pound difference over a 12-year period). However,
when the results were controlled for smoking, exercise, fruit and
vegetable intake, fiber intake, and other confounders, the apparent
benefit of calcium and dairy products disappeared. This suggests
that, in studies implying that calcium or dairy products protect
against weight gain, it is actually other healthy lifestyle factors
that are responsible for weight control.
Rajpathak SN, Rimm EB, Rosner B, Willett WC, Hu FB. Calcium and
dairy intakes in relation to long-term weight gain in US men. Am
J Clin Nutr. 2006;83(3):559-566.
 Obesity Decreases Chance of Surviving Breast Cancer
In a study in Shanghai, China, investigators followed a group of
1,455 women with breast cancer. They found that being overweight
at or soon after diagnosis of breast cancer was related to a
decrease in chance of survival and disease-free survival. This
is one of only a few studies to look at weight’s effect
on breast cancer in an Asian population. Most Asian women are
slim by Western standards. After a five-year follow-up, the survival
rates were higher for those with the lowest body mass index (BMI),
a measure of body weight adjusted for height. The lowest BMI
group had an 86.5 percent survival rate, while the highest BMI
group had an 80.1 percent survival rate. Corresponding disease-free
rates were 81.9 percent for the lowest BMIs and 76.6 percent
for the highest. Excessive adipose tissue, which increases hormonal
activity and stimulates cell growth, may be what promotes the
tumor development and metastasis. The results support previous
findings that weight control can have a substantial effect on
incidence and survival of breast cancer.
Tao MH, Shu XO, Ruan ZX, Gao YT, Zheng W. Association of overweight
with breast cancer survival. Am J Epidemiol. 2006;163:101-107.
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