Author
V.A. Lazar
Bio: V.A. Lazar is an academic researcher. The author has contributed to research in topics: White Muscle Disease. The author has an hindex of 1, co-authored 1 publications receiving 215 citations.
Topics: White Muscle Disease
Papers
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TL;DR: This report presents a map of the U. S. showing areas where the Se content of plants is adequate to protect animals from WMD, and areas where low levels of Se in plants may lead to Se-responsive diseases in animals, and describes how it was prepared.
Abstract: Selenium-responsive diseases of livestock occur frequently
in the United States and have been responsible
for serious economic losses. White muscle disease
(WMD) of lambs and calves is perhaps the most common
of these disorders. The occurrence of WMD is
related to the geologic nature of the soil parent material
(19). There is also evidence that regional patterns of
occurrence of WMD are related to regional differences in
the Se concentration of feed crops (3).
In the U. S., there are also areas where Se toxicity
has been evident in livestock. These areas have been
studied extensively, and the distribution of geologic
formations that form soils capable of producing high-Se
plants has been established (14, 17, 21).
This report presents a map of the U. S. showing
areas where the Se content of plants is adequate to
protect animals from WMD, and areas where low levels
of Se in plants may lead to Se-responsive diseases in
animals, and describes how it was prepared. A similar
survey of plant Se levels has been reported from western
Australia (9).
215 citations
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TL;DR: Severe reproductive impacts were found in aquatic birds nesting on irrigation drainwater ponds in the San Joaquin Valley of California, and aquatic birds may experience similar problems in other areas where selenium occurs at elevated levels.
601 citations
TL;DR: A point-by-point comparison of the chemistry of selenium with the atom it replaces in biology, sulfur, shows that redox chemistry is the largest chemical difference between the two chalcogens.
Abstract: The authors were asked by the Editors of ACS Chemical Biology to write an article titled “Why Nature Chose Selenium” for the occasion of the upcoming bicentennial of the discovery of selenium by the Swedish chemist Jons Jacob Berzelius in 1817 and styled after the famous work of Frank Westheimer on the biological chemistry of phosphate [Westheimer, F. H. (1987) Why Nature Chose Phosphates, Science 235, 1173–1178]. This work gives a history of the important discoveries of the biological processes that selenium participates in, and a point-by-point comparison of the chemistry of selenium with the atom it replaces in biology, sulfur. This analysis shows that redox chemistry is the largest chemical difference between the two chalcogens. This difference is very large for both one-electron and two-electron redox reactions. Much of this difference is due to the inability of selenium to form π bonds of all types. The outer valence electrons of selenium are also more loosely held than those of sulfur. As a result,...
531 citations
TL;DR: The results support earlier findings that higher selenium intakes may reduce the risk of prostate cancer and further prospective studies and randomized trials of this relationship should be conducted.
Abstract: Background In a recent randomized intervention trial, the risk of prostate cancer for men receiving a daily supplement of 200 microg selenium was one third of that for men receiving placebo. By use of a nested case-control design within a prospective study, i.e., the Health Professionals Follow-Up Study, we investigated the association between risk of prostate cancer and prediagnostic level of selenium in toenails, a measure of long-term selenium intake. Methods In 1986, 51,529 male health professionals aged 40-75 years responded to a mailed questionnaire to form the prospective study. In 1987, 33,737 cohort members provided toenail clippings. In 1988, 1990, 1992, and 1994, follow-up questionnaires were mailed. From 1989 through 1994, 181 new cases of advanced prostate cancer were reported. Case and control subjects were matched by age, smoking status, and month of toenail return. Selenium levels were determined by neutron activation. All P values are two-sided. Results The selenium level in toenails varied substantially among men, with quintile medians ranging from 0.66 to 1.14 microg/g for control subjects. When matched case-control data were analyzed, higher selenium levels were associated with a reduced risk of advanced prostate cancer (odds ratio [OR] for comparison of highest to lowest quintile = 0.49; 95% confidence interval [CI] = 0.25-0.96; P for trend = .11). After additionally controlling for family history of prostate cancer, body mass index, calcium intake, lycopene intake, saturated fat intake, vasectomy, and geographical region, the OR was 0.35 (95% CI = 0.16-0.78; P for trend = .03). Conclusions Our results support earlier findings that higher selenium intakes may reduce the risk of prostate cancer. Further prospective studies and randomized trials of this relationship should be conducted.
522 citations
TL;DR: Selenium exerts a strong protective action against the poisoning effects of many heavy metals and of some organic toxicants in birds, mammals, and man and may also be a needed micronutrient for man, but the data are sparse.
Abstract: (1980). Toxicology of selenium: A review. Clinical Toxicology: Vol. 17, No. 2, pp. 171-230.
403 citations
TL;DR: Selenium prevents several type of chemically induced cancer in animals, and, where more selenium occurs in the environment, human cancer death rates are lower and human heart disease mortality is lower.
341 citations