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Biomedical subjects

C Davis

Publications and source records attributed to C Davis.

At least 199 records · Page 11Linked to original sources
PubMed1994

Relationship between evoked potentials and clinical status in spinal cord ischemia.

STUDY DESIGN: Sciatic neurogenic motor-evoked potentials (sciatic-NMEP), spinal-evoked potentials (spinal-EP), and somatosensory-evoked potentials (SEP) were recorded in the lumbar cord during progressive ligation of segmental arteries. Relationship between electrophysiologic assessment and clinical status was studied. OBJECTIVES: In 12 anesthetized dogs that had arterial ischemia of the lumbar cord produced by ligation of segmental arteries, the aforementioned evoked potentials were recorded, and their presence or absence was compared with the clinical status of repeated wake-up tests. SUMMARY OF BACKGROUND DATA: Both sciatic-NMEP loss and ligation level producing cord ischemia were not associated with severity of wake-up test. Sciatic-NMEPs were lost earlier than spinal-EP and SEPs after progressive ligation. The false-negative rate of sciatic-NMEP, SEP at high spine and at low spine was 12.5%, 20.8%, and 41.7%, respectively. The waveform morphology of potentials by cord ischemia decreased in amplitude and in the number of peaks without a shift of latency. METHODS: First, baseline NMEPs and SEPs were obtained, lumbar arteries were ligated, evoked potentials were recorded continuously, and wake-up test was administered. If sciatic-NMEPs were not lost, intercostal arteries were ligated, and potentials and clinical status were reassessed. RESULTS: Though these results were complicated, sciatic-NMEP was more sensitive to the spinal cord ischemia and a better predictor of clinical outcome than spinal-EP and SEP. However, the presence was not a guarantee of normal function. Somatosensory-evoked potentials are not a good predictor of clinical motor status. The initial morphologic change of these potentials secondary to ischemia consisted of a decrease in amplitude and in the number of peaks without a shift of latency. CONCLUSIONS: The peripheral-NMEP is a better warning system to spinal cord ischemia and its adoption may prevent cord ischemia during surgery, whereas SEP and spinal-EP can not be indicies.

Animals↗
PubMed1994

The influence of body fat content and bone diameter measurements on body dissatisfaction in adult women.

This study investigated the simultaneous influence of various anthropometric factors on body dissatisfaction in adult women while controlling for psychological and behavioral factors known to covary with it. Multiple regression analyses confirmed that neuroticism, skeletal frame size, and percent body fat were positively, and age and physical activity inversely, related to dissatisfaction. Subsequent analyses substituted separate bone diameter measurements in place of the composite frame size variable and found that hip diameter, correcting for fatness, was a more salient factor in the determination of body dissatisfaction than the more general estimate of frame size. In pursuit of the perfect ultra-slender body women are encouraged to diet and exercise for weight loss more than ever before. It appears, however, that anatomical factors that are resistant to change by caloric restriction or physical activity, are a significant influence in the degree to which women report discontent with their body shape.

Adolescent↗
PubMed1994

Results of mucosal proctectomy versus extrarectal dissection for ulcerative colitis and familial polyposis in children and young adults.

Over a 5-year period, the authors examined 30 consecutively treated patients, aged 16 years or younger, who underwent total colectomy and ileal pouch-anal anastomosis, (IPAA) using two different surgical methods. In 16 patients (group I), extrarectal dissection with stapled J pouch and anastomosis was performed. In 14 patients (group II), mucosal proctectomy with hand-sewn S pouch and anastomosis was performed. The mean follow-up period this study was approximately two years (range, 1 to 5 years). With regard to postoperative complications, quality of life, and occurrence of pouchitis, there were no significant differences between the groups. Stool frequency was not significantly different between the two groups, and approached four bowel movements per day at 1 year after surgery. In both groups, daytime continence was achieved by all patients 6 months after surgery. A greater number of patients in group II demonstrated temporary nocturnal leakage than in group I, but this difference was not statistically significant (P = .09). The authors conclude that both methods of IPAA are equally effective in preserving normal sphincter function. In patients with severe rectal inflammation, extrarectal dissection with stapled anastomosis may obviate the need for extended preoperative hyperalimentation or subtotal colectomy, but may carry a small increased risk of recurrent anorectal inflammation. The long-term risk of dysplasia is unknown, but may be slightly higher after extrarectal dissection with stapled anastomosis. Further study of both methods of IPAA is recommended.

Adenomatous Polyposis Coli↗
PubMed1994

The role of physical activity in the development and maintenance of eating disorders.

This study was intended to establish the pathogenic significance of sport and exercise in the development of eating disorders. Hospitalized eating disordered patients and an age-matched control group were assessed. Historical and current physical activity data were collected. An indepth interview was also conducted to ascertain the age of onset of the diagnostic symptoms for eating disorders, and to determine whether: (i) exercising predated dieting; (ii) patients had been involved in competitive athletics; (iii) exercise was excessive; and (iv) weight loss was inversely related to level of exercise. The results indicated that patients were more physically active than controls from adolescence onwards, and prior to the onset of the primary diagnostic criteria for anorexia nervosa. A content analysis of the interview data indicated that 78% of patients engaged in excessive exercise, 60% were competitive athletes prior to the onset of their disorder, 60% reported that sport or exercise pre-dated dieting, and 75% claimed that physical activity levels steadily increased during the period when food intake and weight loss decreased the most. Together our results suggest that overactivity should not be routinely viewed as a secondary symptom in anorexia nervosa, equivalent to other behaviours. For a number of anorexic women, sport/exercise is an integral part of the pathogenesis and progression of self-starvation.

Adolescent↗
PubMed1994

Exercise-induced analgesia and the role of reactivity in pain sensitivity.

The present study was designed to evaluate whether pain perception and pain tolerance are altered by submaximal aerobic exercise. Sixty male volunteers were randomly assigned to one of two control or experimental groups in the first of two sessions. In session 1, baseline measures of pain tolerance and pain perception were obtained for half of the subjects in each of the experimental and control groups, respectively. In addition, all subjects completed the Reactivity Scale, followed by estimation of their maximum aerobic power (VO2 max) using the Canadian Home Fitness Test. In session 2, the subjects in the two experimental groups exercised for 12 min by climbing a double step to pre-recorded musical cadences, working on average at 63% VO2 max, whereas the subjects in the two control groups spent approximately 12 min completing two short unrelated questionnaires. Measures of pain tolerance and pain perception were obtained from all subjects after exercising or completing questionnaires. Pain tolerance was assessed by the amount of time (up to 10 min) that subjects could voluntarily endure a 2300 g pressure to the index finger of their dominant hand. Pain perception was defined by participants' intensity ratings on an 11-point scale, made at 30 and 60 s. The results showed that reactivity and exercise were significant predictors of pain tolerance, together accounting for approximately 22% of the variance. The finding that submaximal workloads produce analgesia supports the potential usefulness of exercise in therapeutic intervention.

Adolescent↗
PubMed1994

Achieving dietary recommendations: whole-grain foods in the Food Guide Pyramid.

The Food Guide Pyramid illustrates USDA's food guide developed to help people follow the Dietary Guidelines for Americans. Unlike earlier food guides, the new food guide specifies foods for a total diet; that is, it addresses both concerns about adequacy and moderation. The food guide recommends increased intakes of the vegetable, fruit, and grain groups with special emphasis on dark-green leafy vegetables, legumes, and whole-grain products. These foods are important sources of several vitamins and minerals, complex carbohydrates, and dietary fiber, and they are generally low in fat. Analyses of expected nutrient levels provided by the food guide diet patterns indicate that the nutrient contribution of whole-grain products is particularly important for diets at lower calorie levels. In these diets, it is recommended that at least half the number of servings in the grain group be whole-grain products. In all diets, it is recommended that several servings of whole-grain products be included each day. Average intakes of vegetables, fruits, and grain products are less than recommended. The pyramid graphic has been especially helpful in emphasizing to the public the importance of increased consumption of vegetables, fruits, and grain products for a healthful diet.

Diet↗
PubMed1994

Comparative profile of tizanidine in the management of spasticity.

The therapeutic profile of a new antispastic drug cannot be defined solely on the basis of placebo-controlled studies. Its potential advantages must be evaluated in comparison with existing drugs. This review compares the efficacy and tolerability of tizanidine, a newer muscle relaxant, with that of baclofen and diazepam, the most widely used antispastic agents, for a variety of diagnoses and target symptoms associated with spasticity. More than 20 double-blind, comparative studies were conducted between 1977 and 1987. These included a total of 777 patients suffering from spasticity of various causes. The collected clinical data have been integrated into a combined analysis. Tizanidine emerges from this comparison as a valuable drug in the treatment of spasticity related to cerebral and spinal disorders.

Activities of Daily Living↗
PubMed1993

Body composition correlates of weight dissatisfaction and dietary restraint in young women.

Previous research found that when Body Mass Index (BMI) was statistically controlled in a multiple regression model, the percentage of body fat accounted for no additional variance in dietary restraint scores among women although, on its own, it was a significant predictor of this variable. These results imply that anatomical factors, besides fatness, influence dieting behaviour. The present study was designed to compare the relative influence on dietary restraint and weight dissatisfaction, of three body composition measures, each of which contributes in a different way to subjective impressions of body size (viz. BMI, body fat content, and skeletal frame size). Measures of emotional reactivity ('neuroticism'), body dissatisfaction, , and body focus were also included in the regression model. Results indicated that these psychological variables were strongly and positively related to restraint. Frame size was also a significant predictor of restraint and weight dissatisfaction. In fact, when frame size was controlled in the regression model, neither percentage of body fat nor BMI were able to explain any additional variance in restraint scores. These findings indicate that weight concerns and dieting behaviour are influenced, at least among young women, more by the size of their skeletal structure than their degree of adiposity. The irony of these findings is obvious and disheartening. An anatomical feature which is essentially resistant to change by dieting or exercise appears to be a primary influence in women's weight dissatisfaction and their tendency to diet. It is acknowledged, however, that this relationship may not obtain among very obese women.

Adipose Tissue↗
PubMed1993

Behavioral frequency and psychological commitment: necessary concepts in the study of excessive exercising.

Efforts to understand the associations among exercising, personality factors, and disordered eating have been the focus of much debate. However, research has been plagued by inconsistent findings, and there is evidence that classification and measurement differences are fundamental to these problems. To date, there are no studies which have defined exercise as a multifaceted construct. The purposes of this study were to establish the factor structure of a questionnaire developed to assess the core features believed to characterize excessive exercisers and to assess relationships between exercise (operationally defined as a function of behaviors and attitudes) and a number of putative risk factors. Results indicated that exercise was strongly related to weight preoccupation among women and men and that, among men, obsessive-compulsiveness was also positively related--findings which support claims that exercising and dieting tend to coexist, and they are associated with an obsessive-compulsive personality profile.

Adolescent↗
PubMed1993

Colour Doppler imaging of the acute paediatric scrotum.

The differentiation of the causes of acute scrotal pathology by clinical means alone is prone to inaccuracy, resulting in inappropriate surgical exploration. Colour Doppler imaging (CDI) provides the facility to assess blood flow. Torsion of the testis impedes blood flow, whereas it is enhanced or normal in inflammatory pathology. We have investigated 40 cases of acute scrotal disease by means of CDI in which the radiologist performing the test was unaware of the preliminary clinical diagnosis. The clinical diagnostic accuracy was 60%, whereas the diagnostic accuracy of CDI was 82%. CDI provides an effective means of enhancing diagnostic accuracy.

Acute Disease↗
PubMed1993

Acute effects of marijuana smoking on aggressive, escape and point-maintained responding of male drug users.

Aggressive, escape and point-maintained operant responding of male marijuana smokers were measured during six 25-min sessions conducted over an 8-h experimental day. Aggressive responding ostensibly subtracted points exchangeable for money from another subject. Escape responding protected the subject's counter from point subtractions initiated by the other subject for some period of time. Aggressive and escape responding were engendered by subtracting points from the subjects and maintained by initiation of intervals free of point subtractions. Point subtractions presented to the subjects were attributed to other persons. Subjects earned points exchangeable for money on a third response option. Subjects participated in one session prior to smoking and five sessions after smoking. Subjects smoked placebo or three different potencies of active marijuana cigarettes. Marijuana smoking effects on escape responding were not significant and depended upon the frequency of provocation. Point-maintained responding was decreased after marijuana smoking. Aggressive responding was increased for the first hour after smoking and returned to placebo levels later in the day. These effects of marijuana smoking on aggressive responding are discussed in terms of subject characteristics, particularly drug use history.

Adult↗
PubMed1993

Perinatal factors influencing survival at twenty-four weeks' gestation.

OBJECTIVE: Our objective was to identify those obstetric and neonatal factors associated with survival in infants delivered at 24 weeks' gestation. STUDY DESIGN: The obstetric and pediatric data bases from the two hospitals in our perinatal center were examined to ascertain all infants delivered between 1987 and 1989 whose gestational age was 24 weeks to 24 weeks 6 days. This time interval was chosen to coincide with the introduction of prophylactic exogenous surfactant. Data were abstracted from the maternal antepartum and intrapartum records and the neonatal records, with specific attention to objective risk factors related to survival. RESULTS: Forty-five pregnant patients were identified and delivered of 52 infants. Seventeen newborn infants survived (33%). Univariate comparisons between survivors and nonsurvivors revealed more aggressive intrapartum care in the former cohort as represented by the frequencies of internal fetal heart rate monitoring (p = 0.005), maternal oxygen therpay (p = 0.003), and maternal position change to remediate decelerations (p = 0.001). Planned exclusion of cesarean delivery was more common in those pregnancies that ended in fetal or neonatal death (29/35 vs 7/17; p = 0.006). Although a greater proportion of infants delivered by cesarean section survived (6/11 vs 11/41), this difference was not significant (p = 0.17). With the use of logistic regression, the best predictor of survival was gestational age at delivery. Neonatal care was more aggressive among survivors, as measured by the relative frequencies of resuscitation and surfactant administration. Respiratory distress syndrome was either absent (n = 6) or mild (n = 6) in a majority of the survivors, and respiratory insufficiency was the major cause of neonatal death. CONCLUSION: Perinatal outcome at 24 weeks' gestation appears most dependent on gestational age at delivery. The intensity of intrapartum care and neonatal support, as well as clinical biases regarding survivability, may also influence outcome.

Birth Weight↗
PubMed1993

A mutation in CFTR produces different phenotypes depending on chromosomal background.

Cystic fibrosis (CF) is caused by mutations in the CF transmembrane conductance regulator (CFTR) gene but the association between mutation (genotype) and disease presentation (phenotype) is not straightforward. We have been investigating whether variants in the CFTR gene that alter splicing efficiency of exon 9 can affect the phenotype produced by a mutation. A missense mutation, R117H, which has been observed in three phenotypes, was found to occur on two chromosome backgrounds with intron 8 variants that have profoundly different effects upon splicing efficiency. A close association is shown between chromosome background of the R117H mutation and phenotype. These findings demonstrate that the genetic context in which a mutation occurs can play a significant role in determining the type of illness produced.

Base Sequence↗
PubMed1993

Human submandibular saliva aggregates HIV.

Incubation of HIV with human whole, parotid, or submandibular saliva leads to a decrease in viral infectivity in Sup-T1 cells. The effect is most pronounced with submandibular saliva. Inhibition is seen within 2 min, and increases with time. There is little inhibition seen after incubation of saliva with HSV, and no effect with adenovirus, suggested that there is some viral specificity. Electron microscopic studies revealed that HIV-saliva aggregates are trapped in 0.45-microns pore size nitrocellulose filters. If these inhibitory effects are manifest in vivo, this could account for the low level of virus detected in oral secretions.

Adenoviridae↗