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Biomedical subjects

M M Clark

Publications and source records attributed to M M Clark.

At least 19 recordsLinked to original sources
PubMed1998

Morphology of the inferior frontal gyrus in developmentally language-disordered adults.

The inferior frontal gyrus has traditionally been considered an important cortical region for language and may be important for understanding developmental language disorders. The morphology of the inferior frontal gyrus, as it appeared on T1-weighted sagittal magnetic resonance imaging (MRI) scans, was evaluated using a classification system that distinguished between seven basic morphological variants of the gyral and sulcal patterns in this region. This classification scheme was applied to the MRI scans of 41 neurologically normal adult subjects. To examine the relation between sulcal morphology and subject status, these subjects were sorted first by family history for developmental language disorders and then resorted by expression of behavioral signs consistent with a diagnosis of this disorder as determined by standardized testing. Morphological types that included an extra sulcus in the inferior frontal gyrus were statistically associated with the behaviorally based classification of subjects, but not with a positive family history for developmental language disorders. Because gyral patterns are prenatally determined, this finding is consistent with the theory that altered prenatal development contributes to the expression of a developmental language disorder.

Adult↗
PubMed1998

Intrauterine position, parenting, and nest-site attachment in male Mongolian gerbils.

We housed male Mongolian gerbils, their mates, and foster litters of standardized size and sex ratio in enclosures that provided cover in two locations. Males had been gestated in known intrauterine positions: either between two females (2F males) or between two males (2M males). From Days 1 to 20 postpartum, we examined the frequency with which both males and females were in contact with the pups they were rearing. We found that 2F males spent more time with pups than did 2M males both during entire observation periods and when females were away from the nest. Further, when pups were moved from the nest site. 2M males spent more time than did 2F males in the vacated nest site. We concluded that 2F male gerbils spent more time with pups than 2M males not because of a greater attachment of 2F than 2M males to places of concealment, their male, or their nest site. Rather, 2F males were more attracted to pups than were 2M males.

Analysis of Variance↗
PubMed1997

Reproductive profiles of adult Mongolian gerbils gestated as the sole fetus in a uterine horn.

We compared reproductive profiles of Mongolian gerbils gestated alone in a uterine horn (Isolate males and Isolate females) with those of gerbils gestated in intrauterine positions between two male fetuses (2M males and 2M females) and two female fetuses (2F males and 2F females). We found that, when adult, the reproductive profiles of gerbils that had been gestated as isolates resembled that of gerbils that had been gestated as 2F fetuses: 1. Isolate females gestated litters containing both the same proportion of males as the litters of 2F females and a significantly smaller proportion of males than litters of 2M females. 2. Isolate males, like 2F males, were less likely to impregnate females than were 2M males, and 3. both 2F males and isolate males exhibited disturbed patterns of copulation and reduced levels of scent-marking relative to 2M males. Our results were entirely consistent with the view that intrauterine exposure to males, but not to females, was responsible for previously described differences in the reproductive profiles of 2M and 2F Mongolian gerbils.

Animals↗
PubMed1997

Effects of intrauterine position on the metabolic capacity of the hypothalamus of female gerbils.

The intrauterine position that a rodent fetus occupies relative to members of the same or opposite gender affects both its reproductive physiology and behavior when adult. Cytochrome oxidase histochemistry was used to assess regional differences in the oxidative metabolic capacity of the hypothalamus of female Mongolian gerbils that developed in utero between 2 female fetuses (n = 15) or between 2 male fetuses (n = 14). Cytochrome oxidase reactivity was measured densitometrically by experimenters unaware of subject intrauterine position. Gray-to-white matter ratios of optical density in 11 brain regions were used as a normalized index of metabolic capacity. Significant group differences in the metabolic capacity of the medial and the posterior parts of the anterior hypothalamus were revealed. Females that developed in utero between 2 male fetuses showed significant increases (19-22%) in cytochrome oxidase reactivity in these brain regions compared to that in females that developed between 2 female fetuses. The medial part of the anterior hypothalamus contributes to copulatory behavior, whereas the posterior part of the anterior hypothalamus may be involved in the control of pituitary gonadotropin secretion. Both these functions are influenced by intrauterine position during fetal life. To our knowledge, this is the first demonstration of metabolic changes in hypothalamic areas of the adult related to the differences in intrauterine position.

Animals↗
PubMed1997

Perceived changes in sexual functioning and body image following weight loss in an obese female population: a pilot study.

This study assessed perceived changes in sexual behavior and body image after weight loss in a clinically obese population. Thirty-two women enrolled in a hospital-based multidisciplinary weight management program completed retrospective questionnaires about their sexual functioning and body image before and after weight loss. Subjects reported significant increases in the frequency of their sexual activity. Subjects also perceived significant improvements in their body image. These findings suggest that obese people experience positive changes in sexual functioning and body image after weight loss.

Body Image↗
PubMed1996

Intrauterine position affects motoneuron number and muscle size in a sexually dimorphic neuromuscular system.

The intrauterine position occupied by a rodent fetus influences the amount of testosterone to which it is exposed before birth. Animals that are gestated between two male fetuses (2M) are exposed to higher circulating levels of testosterone than are animals positioned between two female fetuses (2F) and there are reliable differences in the reproductive physiology and behavior of 2M and 2F animals when adult. To determine whether intrauterine position modifies development of the central nervous system, we examined the sexually dimorphic spinal nucleus of the bulbocavernosus (SNB) in male and female gerbils from known intrauterine positions. We found that adult 2M female gerbils had 16% more SNB motoneurons than did 2F females. 2M males did not differ from 2F males in SNB motoneuron number, but the bulbocavernosus muscle, which is innervated by SNB motoneurons, was approximately 50% larger in 2M than in 2F males. These data indicate that intrauterine position can influence the morphology of the sexually dimorphic SNB neuromuscular system.

Animals↗
PubMed1996

Preventive dentistry and the family physician.

Family physicians care for infants and toddlers during a critical period for dental health, and before most children have seen a dentist. The risk of dental disease can be reduced in children by encouraging appropriate diet and hygiene, avoidance of harmful bottle habits, optimal fluoride intake and application of dental sealants to permanent posterior teeth. Fluoride effectively reduces dental caries, but combined intake from water, beverages, foods, dentifrices and inappropriate supplementation has led to an increase in dental fluorosis. New guidelines for fluoride use recommend that fluoride supplementation be delayed until the child is six months of age. Physicians can provide parents with valuable counsel related to teething concerns, thumb-sucking and prevention of dental trauma and disease.

Dentistry↗
PubMed1996

Changes in self-efficacy following obesity treatment.

Self-efficacy is an important component in the treatment of obesity. However, there is limited research examining changes in self-efficacy following obesity treatment. In this quasi-experimental study, 26 obese subjects demonstrated significant improvement on the Weight Efficacy Life-Style Questionnaire (WEL) following participation in a 26-week multidisciplinary VLCD program. Subjects demonstrated significant improvement from pre- to post-treatment on total WEL scores and on all five of the situational factors: Negative Emotions, Availability, Social Pressure, Physical Discomfort and Positive Activities. These results provide further construct validity for the WEL and offer guidelines for the amount of change that subjects may demonstrate on the WEL following obesity treatment.

Adult↗
PubMed1996

Sex and intrauterine position influence the size of the gerbil hippocampus.

Sex differences in home range size and spatial ability are predictive of sex differences in the relative size of the hippocampus in rodents. Such differences in behavior and hippocampal volume are presumed to be, in part, the result of differences in perinatal exposure to hormones. We predicted from differences in the size of home ranges of male and female Mongolian gerbils (Meriones unguiculatus) in the wild that the hippocampus of male gerbils would be relatively larger than that of females. We examined the effect of prenatal hormonal influences on hippocampal size by comparing hippocampal volume of males and females from 2F and 2M intrauterine positions to that of randomly selected males and females. We found that, as predicted, randomly selected males had a significantly larger hippocampus, relative to telencephalon, than did randomly selected females. However, males and females from 2F and 2M intrauterine positions did not differ in relative hippocampal size. Possible explanations for the absence of a sex difference in hippocampal size in male and female gerbils from 2F and 2M intrauterine positions are discussed.

Animals↗
PubMed1996

Effects of perinatal testosterone on handedness of gerbils: support for part of the Geschwind-Galaburda hypothesis.

When assuming their species-typical tripodal stance, male Mongolian gerbils (Meriones unguiculatus) use their right forepaw for support more frequently than do females. This experiment determined whether, as N. Geschwind and A. M. Galaburda (1987) have proposed, the direction of such sexually dimorphic lateral asymmetry of forelimb use is affected by perinatal exposure to testosterone (TP). It was found that male gerbils injected with TP when 4 days old were significantly less likely to rest on their right forepaw when in a tripodal stance than were their oil-injected siblings. Female gerbils injected with TP when 6 days old were more likely than oil-injected controls to use their right forepaws for support. The findings demonstrate effects of perinatal exposure to TP on handedness in gerbils and suggest that the relationship between TP exposure and asymmetrical forelimb use is not always as direct as Geschwind and Galaburda's model suggests.

Animals↗
PubMed1996

Classification of adults for family studies of developmental language disorders.

A variety of approaches has been used to classify the status of adult subjects in familial studies of developmental language disorders. In this report, we directly compare the results of four different methods that appear in the research literature. Two of the approaches rely on case history reports, and two are performance-based methods. Subjects included 24 parents (12 mothers, 12 fathers) of children with developmental language disorders and 24 unrelated adult control subjects (12 female, 12 male) who completed case history items and standardized language testing designed for classification purposes. All classification methods identified more parents than control subjects as "affected". However, classification by case history methods resulted in fewer affected adults than classification through standardized testing. This outcome suggests that the variability in classification rates in studies to date may be the result of method rather than subject sample differences.

Adult↗
PubMed1996

Effect of regular terbutaline on the airway response to inhaled budesonide.

BACKGROUND: The rebound increase in bronchial reactivity and fall in forced expiratory volume in one second (FEV1) following treatment with beta agonists seen in several studies has occurred regardless of concurrent steroid therapy. Little is known about the effect of adding beta agonists to corticosteroids, but in a recent study regular treatment with terbutaline appeared to reduce some of the beneficial effects of budesonide. The effects of budesonide alone and in combination with regular terbutaline treatment on lung function, symptom scores, and bronchial reactivity were therefore examined. METHODS: Sixteen subjects with mild stable asthma inhaled budesonide 800 micrograms twice daily for two periods of 14 days with terbutaline 1000 micrograms three times daily or placebo in a double blind crossover fashion. FEV1 and the dose of histamine or adenosine monophosphate (AMP) causing a 20% fall in FEV1 (PD20) were measured before and 12 hours after the final dose of treatment, and changes from baseline were compared. Seven day mean values for daily morning and evening peak expiratory flow (PEF) values, symptom scores, and rescue medication were compared before and during treatment. RESULTS: Morning and evening PEF rose more with budesonide plus terbutaline than with budesonide alone, with a mean difference of 19 l/min occurring in the evening (95% confidence interval (CI) 2 to 36). There was no difference in symptom scores during treatment. Following treatment the mean increase in FEV1 was 150 ml higher with budesonide alone (95% CI-10 to 300). There was no difference between treatments in change in histamine and AMP PD20. CONCLUSIONS: Evening PEF was greater when budesonide was combined with regular terbutaline. There was no evidence of a difference in bronchial reactivity following the two treatment regimens. The findings of a previous study were not confirmed as the reduction in FEV1 after budesonide and terbutaline was smaller and not statistically significant. Further work is needed to determine whether this disparity in findings in the two studies is due to a type 2 statistical error in this study or a spurious finding in the previous study.

Adrenergic beta-Agonists↗
PubMed1996

Effect of cessation of short-term therapy with ipratropium bromide on lung function and airway responsiveness.

Regular exposure to antimuscarinic drugs would be expected to upregulate airway muscarinic receptors and could cause a transient increase in airways obstruction if treatment was stopped or omitted. We have examined peak expiratory flow rate (PEFR) during treatment and forced expiratory flow in one second (FEV1) and airway responsiveness to three constrictor agonists (as the provocative dose of agonist causing a 20% fall in FEV1, (PD20)) following cessation of regular inhaled ipratropium bromide, in 13 subjects with mild stable asthma. Subjects inhaled placebo and ipratropium bromide, 80 microg q.i.d. for 14 days in a cross-over fashion with a 1 week run-in/wash-out period before and after each treatment period. Subjects recorded symptom scores and PEFR throughout the study, and FEV1 and PD20 to histamine, methacholine and metabisulphite were measured before and after cessation of treatment. When compared to baseline, FEV1 was lower after cessation of ipratropium than after placebo, with a significant difference 30 h after the last dose (difference 190 mL; 95% confidence interval (95% CI) 310-70 mL; p<0.02). FEV1 measured 6-10 days later, did not differ significantly. PEFR was significantly lower after cessation of ipratropium than after placebo on Day 15 (19-37 h after the last dose) (mean difference 4.6%; 95% CI 1.6-7.5%; p<0.01) but not on Day 16. There were no significant changes in PD20 histamine, methacholine and metabisulphite, symptom scores or rescue bronchodilator use after cessation of treatment. Thus, transient bronchoconstriction was found around 30 h after cessation of regular therapy with inhaled ipratropium for 2 weeks. The mechanism is unclear, as no evidence of muscarinic receptor upregulation was found. Although the changes were small and unlikely to be important for most patients, the results of this study indicate that the timing of lung function measurements relative to the last dose of ipratropium is important when interpreting the course of lung function in long-term studies.

Administration, Inhalation↗
PubMed1996

Theories and techniques for promoting physical activity behaviours.

The primary goal of this article is to review theoretical models utilised in designing physical activity interventions for healthy adults. Physical activity offers numerous benefits for improved physical and psychological health. However, the majority of the population is sedentary and therefore at increased risk for morbidity and mortality. Many techniques have been developed for intervening with physical activity behaviours, some of which are based on theoretical models. While some of these models show more promise than others, no model is sufficient to thoroughly explain exercise behaviours or how to best intervene. In the final section, recommendations for future research are presented, and promising areas of development in physical activity interventions are discussed. This is not an exhaustive review of theoretical models but rather focuses on models most commonly applied to physical activity.

Adult↗
PubMed1996

Tentative direct antimicrobial susceptibility testing in urine.

PURPOSE: Tentative direct disk susceptibilities in bacteriuria compared to standard techniques were reevaluated. MATERIALS AND METHODS: A sterile cotton swab was saturated with urine and uniformly streaked over the surface of a Mueller-Hinton agar plate. Susceptibility disks were added within 5 minutes and the zone of inhibition around the antibiotic disk was read after 16 to 18 hours of incubation. RESULTS: The tentative direct susceptibilities showed an accuracy of 98.2% compared to standard techniques in 2,906 positive pure cultures. The false-positive rate was 0.53% and the false-negative rate was 0.14%. CONCLUSIONS: Results of tentative direct antibiotic susceptibility in bacteriuria are comparable to those of standard techniques and are obtained 24 hours sooner.

Bacteria↗
PubMed1995

Medical care of the dental patient.

The family physician frequently makes decisions relating to patients' dental health. The physician can address patients' concerns about tooth eruption or the adverse effects of mercury amalgam. Predisposing factors for dental disease, such as use of certain medications, existing medical conditions (e.g., xerostomia) and traumatic injury, often are first noted by the family physician. Dental emergencies, including abscess and avulsion, can be initially managed by the physician and then referred to the dentist. The physician can coordinate care with a dentist when a patient has dental trauma, requires medical management for a dental procedure or has a medical condition that increases the likelihood of dental disease.

Emergencies↗