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Biomedical subjects

B Cotton

Publications and source records attributed to B Cotton.

15 recordsLinked to original sources
PubMed2001

In vitro and in vivo estrogenicity of UV screens.

Ultraviolet (UV) screens are increasingly used as a result of growing concern about UV radiation and skin cancer; they are also added to cosmetics and other products for light stability. Recent data on bioaccumulation in wildlife and humans point to a need for in-depth analyses of systemic toxicology, in particular with respect to reproduction and ontogeny. We examined six frequently used UVA and UVB screens for estrogenicity in vitro and in vivo. In MCF-7 breast cancer cells, five out of six chemicals, that is, benzophenone-3 (Bp-3), homosalate (HMS), 4-methyl-benzylidene camphor (4-MBC), octyl-methoxycinnamate (OMC), and octyl-dimethyl-PABA (OD-PABA), increased cell proliferation with median effective concentrations (EC(50)) values between 1.56 and 3.73 microM, whereas butyl-methoxydibenzoylmethane (B-MDM) was inactive. Further evidence for estrogenic activity was the induction of pS2 protein in MCF-7 cells and the blockade of the proliferative effect of 4-MBC by the estrogen antagonist ICI 182,780. In the uterotrophic assay using immature Long-Evans rats that received the chemicals for 4 days in powdered feed, uterine weight was dose-dependently increased by 4-MBC (ED(50 )309mg/kg/day), OMC (ED(50) 935 mg/kg/day), and weakly by Bp-3 (active at 1,525 mg/kg/day). Three compounds were inactive by the oral route in the doses tested. Dermal application of 4-MBC to immature hairless (hr/hr) rats also increased uterine weight at concentrations of 5 and 7.5% in olive oil. Our findings indicate that UV screens should be tested for endocrine activity, in view of possible long-term effects in humans and wildlife.

Animals↗
PubMed2001

Mushroom bodies and post-mating behaviors of Drosophila melanogaster females.

After mating, Drosophila melanogaster females lay substantially more eggs and mate rarely. Central to these changes is Sex peptide (SP), a male peptide transferred into the female during copulation. Injected into virgins, SP induces the same post mating response as observed after mating. In this study we investigated the role of the mushroom body (MB) in the SP response system. The SP response of females with either chemically ablated or mutant MBs was analyzed. After injection of SP, females with chemically ablated MBs reduce their receptivity and increase their ovulation and oviposition to the level of females with intact MBs. Virgin females with ablated MBs, however, show a constitutively elevated oviposition rate. Hence in untreated females, MBs are not implicated in the SP-induced reduction of receptivity and increase of ovulation. However, they depress the oviposition rate of virgins. Thus, SP has two functions for oviposition: it de-represses the MB-dependent block on the egg laying activity of virgins and additionally stimulates oviposition. SP-injected mushroom body miniature (mbm) females lay fewer eggs, ovulate less frequently, and mate more often than wild-type females. A model of the putative role of MBs and the gene product of mbm in SP-induced oviposition is presented.

Animals↗
PubMed1999

Viability of Trichomonas vaginalis in transport medium.

The ability of Amies gel agar transport medium to maintain the viability of Trichomonas vaginalis was determined by comparing transported vaginal specimens to specimens immediately inoculated into culture medium. The prevalence of trichomonosis in the study population was 26% (68 of 260 women). The immediate inoculation method detected infections in 64 of 68 infected women (sensitivity of 94.1%). The transport method detected 62 of 68 infections (sensitivity of 91.2%). There was no significant difference between the two methods.

Agar↗
PubMed1985

The primary structure of the precursor of chicken mitochondrial aspartate aminotransferase. Cloning and sequence analysis of cDNA.

The mitochondrial isoenzyme of aspartate amino-transferase (mAspAT; subunit Mr 45,000) is synthesized on free polysomes in the cytosol as a precursor of higher Mr (pre-mAspAT; Sonderegger, P., Jaussi, R., Christen, P., and Gehring, H. (1982) J. Biol. Chem. 257, 3339-3345). We have isolated three overlapping cDNA clones that correspond almost to the full length of pre-mAspAT mRNA with 100 nucleotides at the 5' end missing. The mRNA is 2.1 kilobase pairs long and has a 3' noncoding region of 0.7 kilobase pairs. The cDNAs code for the 401 amino acid residues of mAspAT plus an NH2-terminal pre-piece. Deviations from the reported amino acid sequence were found at positions 154 and 202 where the cDNA specifies Gln instead of Glu. The pre-piece consists of 22 amino acid residues, among them 4 arginine and no acidic residues.

Amino Acid Sequence↗
PubMed1985

Detection of specific proenzyme activators in snake venoms by a new immunoabsorbant-chromogenic substrate method.

In separate experiments, antibodies to plasminogen, factor X and protein C were applied to microtitre trays as commonly used in enzyme-linked immunoassays. After incubation with dilute normal human plasma as a source of the corresponding proenzyme antigen, the wells were exposed to dilutions of various snake venoms. After thorough washing, the microtitre tray wells were tested overnight with chromogenic tripeptide substrates known to be relatively specific for the activated forms of the above factors, i.e., plasmin, factor Xa and activated protein C. The immunochromometric assay described detected two new activators of protein C in Agkistrodon piscivorus and Agkistrodon contortrix venoms and a new factor X activator in Agkistrodon rhodostoma venom. Gel filtration of the latter venom indicated that the factor X activator eluted with high molecular weight, was clearly distinct from the peak fibrinogen clotting activity (Ancrod) and appeared to have no procoagulant activity. Although several Bothrops venoms appeared to contain plasminogen activator by this technique, the observed strong chromogenic activity was observed in microtitre wells independently of plasminogen and represented nonspecific amidase activity.

Enzyme Activation↗
PubMed1982

Mutations affecting the indirect flight muscles of Drosophila melanogaster.

The development of the indirect flight muscles of Drosophila melanogaster was studied by analysing mutations that cause flightlessness. Twenty-five mutations on the X-chromosome and two on the third chromosome were examined. The X-chromosomal mutations form ten complementation units. The ten loci were assigned preliminary map positions by meiotic recombination and deficiencies and duplications. The two autosomal mutations represent two genes. Gynandromorph analyses suggest that many of these mutations have their primary effect in the presumptive thoracic muscle region of the embryo. The mutations cause a variety of characteristic defects, such as absence of the bulk of the thoracic muscle mass, or absence of only one of the two fibrillar muscle groups. Electronmicroscopic studies of sixteen mutants representing all twelve loci reveal abnormal myofibrillar organization in some of these mutants, e.g. aberrant or missing Z-bands, or absence of the thin filaments. Mutant protein patterns, obtained by SDS-polyacrylamide gel electrophoresis, show the following differences from wild type: ten mutants are characterized by absence of reduction of the 54 K protein, and most mutants exhibit a reduction and modification of the 80 and 90 K proteins. The absence of reduction of the 54 K protein was strongly correlated with aberrant Z-bands.

Animals↗
PubMed1980

Role of cerebral hemispheric processing in the visual half-field stimulus-response compatibility effect.

Two experiments were conducted to test theories of the stimulus-response (S-R) compatibility effect. Stimuli presented above and below a fixation point in the left and right visual field signaled choice responses in the midsagittal plane. Even though the duration of stimulus presentation in Experiment 1 was sufficiently brief, such that the possibility of eye movements was precluded, a visual half-field S-R compatibility effect was still obtained. That such an effect is found when it can be adequately specified to which hemisphere stimulus information is presented suggests that an explanation in terms of cerebral laterality factors be considered. The second experiment employed arbitrary symbols to represent the spatial property of stimuli used in prior experiments, and a similar pattern of results was obtained. These results are discussed in terms of a functional view of cerebral organization.

Dominance, Cerebral↗