Search PubMed⌕ Search

Biomedical subjects

M Wilson

Publications and source records attributed to M Wilson.

At least 667 records · Page 37Linked to original sources
PubMed1981

A study of the electron transfer properties of the heme undecapeptide from cytochrome c by 1H nmr spectroscopy.

Nuclear magnetic resonance (nmr) spectroscopy has been used to investigate the heme undecapeptide from cytochrome c. Assignments of resonances to specific residues have been made based on spin decoupling, redox titration, and the pH and temperature dependence of resonance lines. An outline structure is presented based on the assignments, secondary shift data, and the x-ray crystal structure of cytochrome c. An equation is derived to relate the width of an nmr line during a redox titration to the percentage of each oxidation state. Using this equation the self-exchange rate constant for electron transfer for the heme peptide is 1.3 x 10(7) M-1 sec-1 at 330 degrees K. Discussion of the self-exchange rate constants of cytochrome c, cytochrome c3, and cytochrome c551 is related to this constant for the heme undecapeptide.

Animals↗
PubMed1981

Suicidal behavior: toward an explanation of differences in female and male rates.

The explanation of sex differences is based on Breed's five "components of a basic suicide syndrome" which appears to be a satisfactory model for explaining male suicide. Thus far it has not been used to explain female suicidal behavior and sex differences in attempts. It appears that if sex differences are noted the model is adequate. This is because the same factors affect the sexes differently; the content and structure of the roles are different. Failure for males is obvious, but the female role is diffuse and lacking in standards for both success and failure. Female commitment to role and cultural goals is not less, just different and diffuse. Rigidity of roles varies but male goals are usually more specific. Shame, when men do blame themselves, is in the context of a narrow role. Contrary to popular belief, isolation of men is probably greater than that of women.

Dominance-Subordination↗
PubMed1980

The effects of vitamin C, vitamin B6, vitamin B12, folic acid, riboflavin, and thiamin on the breast milk and maternal status of well-nourished women at 6 months postpartum.

The effects of vitamin supplements and/or diet on the vitamin levels in milk of women were determined at 6 months postpartum. Six subjects consumed a daily supplement (Natalins, Mead-Johnson) in addition to a well-balanced diet--supplemented group, and six subjects consumed only a well-balanced diet--nonsupplemented group. The subjects expressed milk for 3 days at 4-hr intervals, 0, 4, 8, and 12 hr after awakening or taking their vitamin supplement. A 4-day diet record, fasting blood sample, and 24-hr urine samples were collected on each subject at 6 months postpartum. Nutrient intake from diet alone did not differ significantly between the two groups except for riboflavin intake which was significantly higher in the supplemented group. The nutritional status of all women indicated excellent dietary intakes, which vitamin supplementation did not alter significantly. Milk concentration of vitamin B6, vitamin B12, folate, thiamin, riboflavin, and vitamin C, did not differ significntly between groups. Thiamin, vitamin B12, and vitamin B6 concentration in the milk did appear to plateau during the day. Vitamin supplementatin at 6 months postpartum did not affect the breast milk concentration or the nutritional status of well-nourished women.

Ascorbic Acid↗
PubMed1980

Behaviour of the rod network in the tiger salamander retina mediated by membrane properties of individual rods.

1. The spread of electrical signals between rods in the salamander retina was examined by passing current into one rod and recording the voltage responses in nearby rods. Rod network behaviour, measured in this way, was simulated from data on rod membrane properties gathered in voltage-clamp experiments on single isolated rods.2. The network voltage responses to square current pulses became smaller, more transient, and had a longer time-to-peak, for rods further away from the site of current injection. Depolarizing currents produced smaller responses than hyperpolarizing currents of the same magnitude.3. Neighbouring rods and cones were coupled less strongly than neighbouring rods.4. The response of the rod network to current injection was unaffected by 2 mm-aspartate(-), which eliminates transmission from receptors to horizontal cells.5. The input resistance of single isolated rods, measured at the resting potential, varied between 100 and 680 MOmega. The lower values were probably due to damage by the micro-electrodes. Electrical coupling was found to be very strong between the rod inner and outer segments.6. A strong ;instantaneous' outward rectification seen in isolated rods at potentials positive to -35 mV was reduced, but not abolished, by 15 mm-TEA.7. In normal solution, isolated rods exhibited a voltage- and time-dependent current, I(A), whose kinetics were approximated by a single first-order gating variable, and whose activation curve spanned the range between -40 and -80 mV. The time constant for the current varied with voltage and was 60-200 msec between -140 and -40 mV.8. A reversal potential for I(A) could not be found between -140 and -40 mV in normal solution, and the fully activated current, I(A), was approximately voltage-independent, with a magnitude of approximately 0.1 nA over this potential range.9. By several criteria, I(A) behaved as a single inward current activated by hyperpolarization. Pharmacological studies suggest, however, that it is the sum of at least two currents with very similar kinetics.10. Most isolated rods exhibited a very slow (tau approximately 3 sec) increase in net outward current on depolarizing beyond -35 mV. The magnitude of this current varied considerably between cells.11. Assuming that the rod network can be approximated by a square lattice of individual rods, resistively coupled together, the voltage-clamp data on isolated rods were used to predict the response of the network to current injection at one cell. The theoretical and observed network behaviour were in good agreement. The resistance coupling neighbouring rods was estimated to be approximately 300 MOmega. The current I(A) plays a major role in determining the behaviour of the rod network.12. The time-dependent current, I(A), is responsible for the peak-plateau wave form of the response to a bright flash. A current similar to I(A) could also account for the negative propagation velocity of the peak of the dim flash response, through the rod network of the turtle, observed by Detwiler, Hodgkin & McNaughton (1978).

Animals↗
PubMed1980

Serologic cross-reactions with sera from patients with echinococcosis and cysticercosis.

Serum specimens from persons with pathologically confirmed Echinococcus granulosus hydatidosis and Taenia solium cysticercosis were tested in indirect hemagglutination tests using both Echinococcus and Taenia antigens. There were cross-reactions with most sera, and it was not possible to distinguish specific reactions by comparing titers with the homologous or heterologous antigens. Using immunoelectrophoresis or double diffusion tests with E. granulosus antigens, the Echinococcus-specific arc 5 was demonstrated in 11 of 21 hydatidosis sera and in 1 of 20 cysticercosis sera.

Adolescent↗
PubMed1979

Age and sex specific reference limits for carbohydrate tolerance.

Glucose estimations in the absence of diabetic symptoms may lead to diagnostic problems when clinicians are confronted with borderline results. This study on 28 581 estimations of post-prandial plasma glucose values gives age and sex specific reference limits derived from regression analysis at the 97.5 percentage point. A linear relationship exists between age and glucose tolerance in both sexes which is affected by the time of specimen collection. No evidence was found in support of bimodality; hence, it is believed that the observed diminution of carbohydrate tolerance with age is characteristic of the entire population.

Adult↗
PubMed1979

Inhibition of mammary tumorigenesis in GR mice with 2-bromo-alpha-ergocryptine.

A high incidence of mammary tumors is found in multiparous GR mice during the 2nd and 3rd pregnancies and in nulliparous GR mice treated with estrone/progesterone. The purpose of this study was to determine if prolactin is a contributing hormone in the genesis of these neoplasms. In one series of experiments, 238 15-week-old nulliparous GR mice were treated with estrone (drinking water, 0.5 mg/liter) plus progesterone (30 mg progesterone pellet with cholesterol, implanted SC once monthly) for a period of 13 weeks. Half of these mice were injected SC once daily with 100 micrograms of the prolactin-suppressing drug 2-bromo-alpha-ergocryptine (CB-154) for the duration of hormone treatment, and the other half were injected SC once daily with 0.9% NaCl solution (controls). In another series of experiments, 87 pregnant GR mice were divided into two groups and injected SC once daily from day 7 to 21 of pregnancy with 0.9% NaCl solution (controls) or CB-154 (100 micrograms/mouse). In the first series, the numbers of mice with mammary tumors and total number of mammary tumors were: controls, 58/119 (49%) and 73; CB-154 treatment, 34/119 (29%) and 37, respectively. In the second series, the numbers were: controls, 39/44 (89%) and 73; CB-154 treatment, 24/43 (56%) and 43, respectively. In both studies, CB-154 treatment significantly (p less than 0.05-0.005) reduced the percentage of mice with mammary tumors and total number of mammary tumors. These results provide evidence that prolactin is a contributing hormone in the genesis of estrone/progesterone and pregnancy-induced mammary tumors in female GR mice.

Animals↗