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Biomedical subjects

M M Clark

Publications and source records attributed to M M Clark.

At least 73 records · Page 4Linked to original sources
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↗
PubMed1986

Responses to novel odors mediate maternal behavior and concaveation in gerbils.

In a series of three experiments we examined: (Experiment 1) responses to novel odors by early- and late-maturing not-pregnant, pregnant, nursing and postweaning female Mongolian gerbils, (Experiment 2) the response of the same eight groups of female gerbils to unfamiliar pups, and (Experiment 3) the rate of induction of maternal behavior by concaveation in early- and late-maturing nulliparous gerbils. We found: (1) that those females that responded relatively positively to novel odors in Experiment 1 were more likely to retrieve and less likely to attack unfamiliar pups in Experiment 2 than those females responding relatively negatively to novel odors in Experiment 1, and (2) that early-maturing nulliparous gerbils both responded more positively to novel odors and exhibited more rapid induction of maternal behavior by concaveation than late-maturing nulliparous gerbils. The results both confirm and extend Fleming and Rosenblatt's (1974) hypothesis that differences in response to novel odors mediate individual differences in maternal responsiveness.

Animals↗
PubMed1986

Postnatal effects on reproduction and maternal care in early- and late-maturing gerbils.

In previous papers, we have identified a number of differences in both the reproductive profiles and patterns of maternal care shown by female gerbils exhibiting vaginal opening either before or after weaning. Early-maturing females delivered their first litters when younger, produced a greater percentage of female offspring/litter, and a greater percentage of early-maturing daughters than late-maturing females. Further, early-maturing females exhibited reduced levels of maternal care, as assessed by time spent nursing, time pups were gathered in the nest, and probability of retrieval of displaced young. In the present experiments, we found that equating age at first parity of early- and late-maturing females (Experiment 1) eliminated differences between them in pup gathering, but not in pup retrieval or nursing. Further, equating age at first parity affected neither sex-ratios of litters at birth nor rate of maturation of daughters. Equating litter size at birth, sex-ratio of litters at birth, and maternal age at first parturition (Experiment 2) eliminated differences in the nursing behavior of early- and late-maturing females and reduced differences in retrieval behavior, but left rate of maturation of daughters unaffected. Last (Experiment 3), both daughters born to early-maturing females, reared by late-maturing females, and daughters born to late-maturing females, reared by early-maturing females, exhibited rates of maturation typical of daughters reared by their natural mothers.

Age Factors↗
PubMed1986

An investigation of factors affecting postoperative rewarming of adult patients.

Aural canal temperature was measured for one hour after arrival in the recovery room in 200 adult patients who underwent one of the following types of major surgery: abdominal, pelvic, vascular, orthopaedic or prostatic. One group of 100 patients was studied in the recovery room of Hammersmith Hospital which was not equipped with a controlled system for constant ventilation and humidification, while the other 100 patients were studied in the recovery room of Edgware General Hospital, which had a constant ambient temperature and controlled relative humidity with 20 air changes/hour. The rate of rewarming was found to be similar in both groups. Within the range of ambient temperatures and relative humidities measured, patients over 60 years of age rewarmed more slowly than did patients under 60 years (p less than 0.05). General anaesthesia was associated with significantly faster rewarming than was local anaesthesia (p less than 0.01).

Age Factors↗
PubMed1986

Impaired chemotaxis and neutrophil (polymorphonuclear leukocyte) function in glycogenosis type IB.

Polymorphonuclear leukocyte (PMN) function was investigated in two patients with glycogen storage disease type IB and neutropenia. Glycogen storage disease type IB was documented by liver biopsy and a normal amount of latent glucose-6-phosphatase activity. Patient A had stomatitis, skin infections, and septicemia; patient B had respiratory infections, periodontitis, and oral candidiasis. Absolute neutrophil counts ranged from 114 to 2580/mm3. Diminished and delayed migration of PMN into a skin "window" occurred in B. Random and directed PMN migration under agarose toward f-Met-Leu-Phe, pepstatin A, and zymosan-activated serum were severely diminished in both patients. At 10(-7) M f-Met-Leu-Phe, mean random and directed migration were 52 and 23% (A, n = 3) and 48 and 13% (B, n = 4) of controls. These results were independent of incubation time and chemoattractant concentration. Patients' PMN had diminished quantitative nitroblue tetrazolium reduction compared to controls. B had a significant defect in PMN bactericidal activity with Escherichia coli with less than 0.2 log killing at 2 h. These results further characterize the defect in PMN migration reported by Beaudet et al. (J Pediatr 97:906, 1980). The finding of other abnormalities of PMN function suggests a metabolic defect in the neutrophil which may be related to the microsomal membrane defect in hepatocytes in glycogen storage disease type IB.

Adolescent↗
PubMed1986

Improving the productivity of breeding colonies of Mongolian gerbils (Meriones unguiculatus).

The productivity of breeding colonies of Mongolian gerbils can be substantially enhanced by using as breeding stock only the 40% of females that exhibit vaginal opening before reaching 25 days of age. Early-maturing females are more likely to breed successfully on first pairing. The lifetime fecundity of early-maturing females is more than twice that of their late-maturing sisters. In those cases in which early-maturing females fail to breed with the first male with which they are paired, they (but not late-maturing females) can be mated with a second male with a high probability of success. Two-thirds of the early-maturing females that failed to reproduce following a first pairing became pregnant following a second. Only 11% of late-maturing females did so.

Age Factors↗