HÉMA-VIGIE…always on the lookout! A Monthly Newsletter Summarizing Important Advances in Transfusion Volume 3, Number 1 West Nile virus – infected birds: an early
tral role in the peripheral circulation problems commonly
warning sign of upcoming human infec-
encountered in sickle-cell disease patients.
Reiter, C. D., et al. (2002). Cell-free hemoglobin limits nitric oxide bioavailability in sickle-cell disease. Nat
To gain further insights on this emerging pathogen, Gup-
Med 8 (12): 1383-1389. doi: 10.1038/nm799.
till et al. (U.S. Geological Survey, VA, USA) analyzed
epidemiological data on the prevalence of infected birds and human infections per US county as a function of time
Are there bacteria in the blood of healthy
in 2001 and 2002. Their results indicate that for a given
individuals?
area, the identification of infected birds early in the sea-
son when the virus is active increases the likelihood of
Up until now, the vascular compartment of healthy indi-
viduals was thought to be devoid of bacteria. The results
of a collaborative effort led by Eddie C. S. Chan (McGill
Guptill, S. C., et al. (2003). Early-season avian deaths
University, Montreal) suggest that bacteria are found in
from West Nile virus as warnings of human infection.
low numbers in the blood of otherwise healthy individuals.
Presumably harmless, the isolated bacteria are particu-
larly difficult to grow, which may partly explain why they
Transmissible spongiform encephalopathies (TSE): Antibodies against prions are protec-
McLaughlin, R. W., et al. (2002). Are there naturally occurring pleomorphic bacteria in the blood of heal- thy humans? J Clin Microbiol 40 (12): 4771-4775. doi:
White et al., under the supervision of Simon Hawke (Im-
perial College, London, United Kingdom) demonstrate
that prophylactic infusion of antibodies specific to the
Gene therapy for anemia by controlled ex-
prion protein prevent encephalopathy in mice previously inoculated with an infectious prion in the abdominal cav-
pression of erythropoietin (EPO)
ity. However, treatment has to be started relatively early
after infection, i.e., before infectious prions reach the
Two articles describing animal models of gene therapy
central nervous system, in order to be efficacious.
designed for treatment of anemia have been recently
published. Samakoglu, Bohl, and Heard (Pasteur Insti-
White, A. R., et al. (2003). Monoclonal antibodies in-
tute, Paris, France) succeeded in controlling EPO ex-
hibit prion replication and delay the development of
pression from a gene therapy vector using a pharmacol-
prion disease. Nature 422 (6927): 80-83. doi:
ogical agent. Furthermore, Binley et al. (Oxford Bio-
Medica (UK) Ltd., Oxford, United Kingdom) designed a
gene therapy vector whereby EPO expression is auto-regulated in response to oxygen concentration in the
Hemolysis-induced vasoconstriction: In-
tissue in which the vector is delivered.
sights on the molecular mechanisms
Samakoglu, S., Bohl, D., and Heard, J. M. (2002). Me-
Sickle-cell disease, an inherited disorder affecting red
chanisms leading to sustained reversion of beta-
blood cell hemoglobin, results in frequent peripheral vas-
thalassemia in mice by doxycycline-controlled Epo
cular occlusions caused by the abnormal rigidity of sick-
delivery from muscles. Mol Ther 6 (6): 793-803. doi:
led red blood cells. These episodes are often associated
with hemolysis, that is, free hemoglobin in blood. A group
led by Mark T. Gladwin (National Institutes of Health,
Binley, K., et al. (2002). Long-term reversal of chronic
Bethesda, MD, USA) presents results suggesting that
anemia using a hypoxia-regulated erythropoietin
nitric oxide inactivation by free hemoglobin plays a cen-
gene therapy. Blood 100 (7): 2406-2413. doi: 10.1182/blood-2002-02-0605.
NOTICE. This newsletter aims at informing Héma-Québec personnel and partners of the most recent scientific developments which may exert an impact in the field of blood and transfusion. The information contained herein should not be interpreted as exhaustive accounts of the findings being presented. Opinions and analyses presented herein constitute personal interpretations of scientific articles and/or newsclips presented to the reader and are the sole responsibility of the author. Héma-Québec denies any liability whatsoever with regards to the use or misuse by the reader of the information contai-ned herein.
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HÉMA-VIGIE…always on the lookout!