PubMed Health⌕ Search

Biomedical subjects

M M Clark

Publications and source records attributed to M M Clark.

At least 19 recordsLinked to original sources
PubMed1992

Intrauterine positions and testosterone levels of adult male gerbils are correlated.

Those male Mongolian gerbils (Meriones unguiculatus) that developed in intrauterine positions between two male fetuses had significantly higher levels of serum testosterone, as adults, than did those adult male gerbils that developed in intrauterine positions between two female fetuses. The endogenous testosterone levels of adult male gerbils were significantly positively correlated with both the sizes of their ventral scent glands and their frequencies of scent marking. We found no evidence of pulsatile release of testosterone in adult male gerbils.

Animals↗
PubMed1992

Increased saliva cotinine concentrations in smokers during rapid weight loss.

Although the effect of smoking cessation on weight gain is well-documented, little is known about the effect of weight loss on smoking. We examined the association between saliva cotinine levels and weight loss in a group of 9 obese female smokers during participation in a protein-sparing modified fast (Optifast). For the first 3 months of treatment, subjects consumed only the protein-sparing supplement; for the next 3 months, food was gradually reintroduced. Body mass index and saliva cotinine concentration were assessed at study entry and at 3 and 6 months. A significant weight loss was noted at 3 and 6 months, yet the cotinine level increased significantly over this time. It is unclear whether the cotinine increase is due to metabolic changes or an actual increase in nicotine intake. The results suggest that smoking-related health risks may increase during periods of significant weight loss.

Adult↗
PubMed1992

Current treatment of obesity: a behavioral medicine perspective.

Obesity is a complex biopsychosocial phenomenon. It has a profound effect on patients' physical and psychological health. Due to the complexity of the problem and the recidivism following treatment, it is recommended that obese patients receive in-depth interdisciplinary evaluation to match them appropriately to comprehensive treatment. Participation in an interdisciplinary comprehensive active weight loss treatment program followed by participation in a professionally led biweekly behavioral maintenance program that included social influence and aerobic exercise has generated maintenance of 83% of initial weight loss at an 18-month follow up. This comprehensive multi-disciplinary treatment approach, best offered in a behavioral medicine center setting, represents state-of-the-art treatment at this time and can result in long-term medical and psychological benefits for the obese patient.

Behavior Therapy↗
PubMed1991

Nonrandom sex composition of gerbil, mouse, and hamster litters before and after birth.

Examining data describing the sex composition of 1074 Caesarean-delivered litters of house mice, 253 Caesarean-delivered and 265 vaginally delivered litters of Mongolian gerbils, and 854 vaginally delivered litters of golden hamsters, we determined whether segregation of sexes between uterine horns and correlations between litter size and litter sex ratio were present in each of the three rodent species studied. Although significant deviations from expected distributions of male and female fetuses were found, these deviations from chance were not the same in any two of the three species examined. Analyses also indicated that the correlation between litter size and litter sex ratio that Huck, Seger, and Lisk (1990) found in vaginally delivered infant hamsters is present in vaginally delivered infant Mongolian gerbils, but not in their Caesarean-delivered colony mates. In gerbils, and perhaps hamsters as well, the correlation between litter size and litter sex ratio appears to be a result of sex-biased perinatal mortality correlated with litter size rather than of sex-biased conception correlated with litter size.

Animals↗
PubMed1991

Unconfounded evidence of sex-biased, postnatal maternal effort by Mongolian gerbil dams.

In previous studies of effects of offspring sex on postnatal maternal effort there has often been unintentional confounding of the sex ratio of the pups that a dam reared with the sex ratio of the litter that she gestated. By controlling the sex ratio of litters that female subjects gestated, we showed that (1) the probability of dams retrieving pups was influenced by the sex ratio of the litters dams gestated, not by the sex of litters that dams reared and (2) both frequency of nursing and duration of vaginal closure were influenced by the sex of litters that dams reared, not by the sex ratios of litters that dams gestated.

Animals↗
PubMed1991

Concentrations of sex steroid hormones in pregnant and fetal Mongolian gerbils.

Sex steroid concentrations in the plasma of 24-day pregnant Mongolian gerbils (Meriones unguiculatus) and their male and female fetuses were measured using radioimmunoassays. It was found that, on Day 24 of gestation: (a) androgen levels were higher in those male fetuses developing adjacent to no female fetuses than in those male fetuses developing between two female fetuses and (b) androgen levels were higher in those female fetuses developing between two male fetuses than in those female fetuses with no immediate, male neighbours. Further, plasma taken from 24-day pregnant dams that had exhibited vaginal opening at a relatively early age had significantly lower androgen levels and significantly higher estradiol levels than did plasma taken from 24-day pregnant dams that had exhibited relatively late vaginal opening. The data provide direct evidence of hormonal mediation of previously described differences both in the morphology and reproductive biology of male and female adult gerbils as a function both of their fetal intrauterine locations relative to members of the other sex and of the age at vaginal introitus of their respective dams.

Animals↗
PubMed1991

Self-efficacy in weight management.

Self-efficacy is an important mediating mechanism in advancing understanding of the treatment of obesity. This study developed and validated the Weight Efficacy Life-Style Questionnaire (WEL), improving on previous studies by the use of clinical populations, cross-validation of the initial factor analysis, exploration of the best fitting theoretical model of self-efficacy, and examination of change in treatment. The resulting 20-item WEL consists of five situational factors: Negative Emotions, Availability, Social Pressure, Physical Discomfort, and Positive Activities. A hierarchical model was found to provide the best fit to the data. Results from two separate clinical treatment studies (total N = 382) show that the WEL is sensitive to changes in global scores as well as to a subset of the five situational factor scores. Treatment programs may be incomplete if they change only a subset of the situational dimensions of self-efficacy. Theoretical and clinical implications are discussed.

Adult↗
PubMed1990

Sexual segregation in the left and right horns of the gerbil uterus: "the male embryo is usually on the right, the female on the left" (Hippocrates).

We examined reproductive tracts of 253 female Mongolian gerbils (Meriones unguiculatus) and recorded the uterine locations (relative to siblings of opposite sex) in which 812 male and 823 female fetuses were found. Within-litter comparisons revealed that sexes were not distributed randomly across uterine horns. The percentage of males in right horns (55.0%) was greater than the percentage of males in left horns (41.8%) and the percentage of females in right horns (45.0%) was significantly less than the percentage of females (58.2%) in left horns. We did not find differences in the total number of fetuses in left and right uterine horns or a sex bias in the total sample of 1635 fetuses. Results were discussed in terms of: (a) effects of sexual segregation of fetuses on expected probabilities of fetuses developing adjacent to 0, 1, or 2 fetuses of opposite sex and (b) consequent alterations in expected frequencies of behavioral phenotypes in populations of gerbils.

Animals↗
PubMed1990

Fetal uterine position affects copulation and scent marking by adult male gerbils.

Those male Mongolian gerbils (Meriones unguiculatus) that as fetuses resided in uterine locations adjacent to no females, when adult, scent marked more frequently, mounted estrous females with shorter latencies, and ejaculated after fewer intromissions than did those male gerbils that as fetuses resided in uterine locations adjacent to two females. Both the scent-marking frequencies and copulatory patterns of adult males were positively correlated with three indices of their circulating levels of testosterone: ventral gland size, anogenital distance, and relative testes weights. Also, those males that scent marked relatively frequently copulated more reliably than did those males that scent marked relatively infrequently.

Androgens↗
PubMed1989

Measuring rates of sexual development in female Mongolian gerbils.

In previous experiments, we have shown that age at vaginal introitus predicts adult patterns of reproductive, maternal, and aggressive behavior of female Mongolian gerbils. In the present series of studies, we explored the relationship in gerbils between age at vaginal patency and three other indices of rate of female sexual development: ovarian weight, occurrence of vaginal estrus, and onset of attractiveness to males. We found that female gerbils, classified on the basis of their ages at vaginal introitus as early-maturing: (a) exhibited greater ovarian weights throughout development than did their late-maturing, female sibs; (b) exhibited estrus and Diestrus I stage vaginal smears and, by inference, ovulation at an earlier age than did late-maturing females; and (c) elicited mounting by males at an earlier mean age than did late-maturing females. The data were consistent with the hypothesis that age at vaginal introitus is a reliable indicator of rate of sexual development in female Mongolian gerbils.

Animals↗
PubMed1989

Uterine positions and schedules of urination: correlates of differential maternal anogenital stimulation.

Lactating Mongolian gerbils, like lactating Norway rats, reliably lick some pups in their litters more than they lick others. Male gerbil pups are licked more by their dams than are their sisters and some males and some females within each litter are licked more often than are their sibs of the same sex. In the present article, we explore the characteristics of same-sex littermates that are correlated with elicitation of extreme amounts of maternal anogenital licking. We found that both the male pup and the female pup in a litter of gerbils that received the most maternal anogenital licking: (1) released greater quantities of urine and (2) exhibited longer latencies to begin to urinate in response to artificial anogenital stimulation than did the male pup and the female pup in a litter that received the least amount of maternal anogenital licking. We also found that foster mothers rearing Caesarean-delivered litters spent more time licking the anogenital areas of: (1) those male pups that, as fetuses, had occupied uterine locations adjacent to relatively few females and (2) those female pups that, as fetuses, had occupied uterine locations adjacent to relatively many males. We discuss implications of these findings for understanding of how maternal behavior may mediate hormonal effects on the development of young gerbils.

Animals↗
PubMed1988

Effects of uterine position on rate of sexual development in female Mongolian gerbils.

Examination of the rate of sexual maturation of 79 female gerbils from 32 Caesarean-delivered, foster-reared litters revealed that those females that, as fetuses, occupied uterine positions adjacent to one or two males (1M and 2M females) were less likely than those females occupying uterine positions not adjacent to males (0M females) to exhibit early vaginal opening. Our data further indicated that the uterine environment provided by late-maturing female gerbils biased their fetal daughters to themselves be late maturing to a greater extent than the daughters' uterine positions could explain. Daughters of late-maturing females in 1M and 2M uterine locations were more likely to be late-maturing than were daughters of early-maturing females in similar uterine locations. Because in female Mongolian gerbils age at vaginal opening is a powerful predictor of future reproductive strategy, the present results indicate that in female gerbils both prenatal maternal influence and uterine location are important determinants of future reproductive behaviors.

Animals↗
PubMed1988

Differentiating the etiology of male erectile dysfunction using the Millon Behavioral Health Inventory and self-report measures.

This study examines the effectiveness of using the Millon Behavioral Health Inventory in conjunction with self-report measures of erectile dysfunction to classify the etiology of erectile dysfunction in males. Subjects were 70 males with erectile dysfunction. The results indicate that 47% of the subjects with psychogenic etiology, 65% with mixed etiology, and 71% of the subjects with organic etiology were correctly classified. These and previous findings indicate that the MBHI is an effective method of assessing the etiology of erectile dysfunction.

Adult↗
PubMed1987

Early education and children with special needs.

Changing issues in the field of preschool education will be discussed, set in the context of two of my studies which have been concerned with children with special needs in 'ordinary' preschool education, one 'pre-Warnock' in Scotland, and the other 'post-Warnock' in the West Midlands. The concept of special needs will then be widened to include children for whom English is a second language, and also gifted children. Finally, the discussion is extended to early education rather than preschool education with a discussion of the dangers of treating preschool education in isolation.

Child, Preschool↗
PubMed1987

Indirect enzyme-linked immunosorbent assay for measurement of human immunoglobulins E and G to purified cow's milk proteins: application in diagnosis of cow's milk allergy.

An indirect double-antibody enzyme-linked immunosorbent assay (ELISA) was developed for the measurement of human immunoglobulin E (IgE) and IgG to the cow's milk proteins (CMP) alpha-casein, alpha-lactalbumin, and beta-lactoglobulin. Human serum albumin was used as the negative-antigen control. Rabbit anti-human IgE or IgG served as the primary antibody, and horseradish peroxidase-conjugated swine anti-rabbit immunoglobulin served as the secondary antibody. Positive control sera were obtained from patients with well-documented histories of cow's milk allergy, while negative control sera were obtained from cord bloods of healthy full-term infants and from normal adult volunteers without known milk allergy. Test sera were obtained from 41 children (ages, 3 months to 13 years; average age, 2.6 years) with suspected cow's milk allergy and clinical manifestations that included wheezing, rhinitis, atopic dermatitis, urticaria, or gastrointestinal disturbances. The patients were simultaneously evaluated by prick skin testing with scratch test antigen to whole CMP. Although only 13 (32%) of the 41 patients were positive by the prick skin test, 25 (61%) were positive by the IgE ELISA. Of the 25 IgE ELISA-positive patients, 20 were also positive by the IgG ELISA. There was concordance of positive results between skin testing and the IgE ELISA in only 9 patients (22%), and there was concordance of negative results in 12 patients (29%). Discordant results were observed in 20 patients (49%). These results indicate that the ELISA is more sensitive than prick skin testing in the identification of individuals with elevated levels of IgE to CMP.

Adult↗