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Biomedical subjects

I Levenson

Publications and source records attributed to I Levenson.

7 recordsLinked to original sources
PubMed1998

New AUG initiation codons in a long 5' UTR create four dominant negative alleles of the Drosophila C2H2 zinc-finger gene ovo.

Promoters active in the germline produce OVO-A and OVO-B mRNAs encoding isoforms of a putative transcription factor. The isoforms have a common C2H2 zinc-finger domain but different N-termini that include potential effector domains. Single point mutations in three dominant-negative ovoD mutations result in new in-frame initiation codons in OVO-B mRNAs and amino acid substitutions within charged regions of OVO-A proteins. Three lines of evidence suggest that the dominant activity is due to the new initiation codons in OVO-B mRNAs and not the amino acid substitutions in OVO-A. First, we made a fourth ovoD allele by inserting a new in-frame AUG. This ovoD4 allele encodes a nearly full-length OVO-A isoform from OVO-B mRNAs. Second, engineered stop codons in ovoD1 downstream of the new AUG abolished dominant negative activity. Third, a substantial deletion of an OVO-A region encoding a highly charged amino acid domain fully rescued loss-of-function ovo alleles. These data suggest that ovoD mutations result in inappropriate expression of OVO-A in the female germline.

Alleles↗
PubMed1991

The effect of low-dose oral contraceptives on lipids and lipoproteins in two at-risk populations: young female smokers and older premenopausal women.

Young women who smoke and women over age 35 are considered to be at high risk for cardiovascular complications associated with oral contraceptive use. This study evaluated the effects of low-dose oral contraceptives on lipid and lipoprotein concentrations in 45 high-risk patients before, during, and after 6 months of treatment. Neither group showed a significant change from baseline in cholesterol, HDL cholesterol, LDL cholesterol or cholesterol ratios. Triglycerides increased and HDL2a levels decreased significantly in both groups but returned to baseline after treatment was discontinued, with the largest changes in both triglycerides and HDL2a levels occurring at 1 month. The change in triglyceride and HDL2a blood levels were within the laboratories' reference range. The lipid profile of these patients, therefore, was not worsened significantly through 6 months of oral contraceptive use. The young women who smoked did have consistently lowered levels of HDL cholesterol and its HDL2a subfraction when compared to their elder non-smoking cohort.

Adult↗
PubMed1985

The effects of low-dose oral contraceptives on coagulation and fibrinolysis in two high-risk populations: young female smokers and older premenopausal women.

A study was undertaken to determine the effect of a low-dose oral contraceptive on the coagulation and inhibitory system of coagulation in 22 young healthy women who smoke and in 15 nonsmoking healthy women between the ages of 34 and 41. Smokers showed statistically significant oral contraceptive-related procoagulant alterations in prothrombin time, thrombin time, and fibrinogen antigen. Antithrombin III antigen and activity were significantly reduced, whereas plasminogen antigen and activity were increased. Inhibitor and fibrinolytic activity was either unaffected or enhanced by oral contraceptives in women over the age of 34: antithrombin III activity was unchanged, plasminogen antigen and activity increased (p less than 0.0007), and alpha 2-antiplasmin was significantly reduced (p less than 0.07). Whereas usage of oral contraceptives in young smokers may initiate biochemical changes in favor of thrombogenesis, their usage in nonsmoking older women enhanced fibrinolysis and had a neutral effect on inhibition and a minimal procoagulant effect.

Adult↗