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Biomedical subjects

C A Bryant

Publications and source records attributed to C A Bryant.

At least 19 recordsLinked to original sources
PubMed2004

Stroke, dementia, and drug delivery.

Stroke and dementia represent a major health burden for elderly subjects as they are associated with significant morbidity and mortality. The rates of stroke and dementia are progressively increasing due to the ageing population in most westernized countries. Therefore, both these conditions represent a major therapeutic target. However, the therapeutic options available for the management of stroke and dementia remain largely unsatisfactory, the main reason being the difficulty in transferring the results obtained in animal and in vitro studies to the clinical setting. This review focuses on the recent advances in pathophysiology and treatment of these conditions and future directions for research. Moreover, the technique of functional magnetic resonance imaging is discussed in detail as a tool to assess the effects of therapeutic agents on the central nervous system and monitor the progression of diseases. Finally, an overview of the issue of drug delivery into the central nervous system is presented.

Anticholesteremic Agents↗
PubMed2001

Developing youth capacity for community-based research: the Sarasota County demonstration project.

Although youth involvement in health promotion efforts is not a new concept, projects that actively involve youths in planning research, collecting data, and making research design decisions are rare. This article describes the evaluation process and outcomes for a youth-directed data collection initiative. Eleven youth researchers conducted 112 personal in-depth interviews and 22 focus groups involving 206 youths in 5th through 12th grade. Youth researchers felt confident they could conduct focus groups and in-depth interviews and staff ratings of youths' effectiveness in moderating focus groups indicated they were successful in carrying out the qualitative research.

Adolescent↗
PubMed2000

Chronic daily ethanol and withdrawal: 1. Long-term changes in the hypothalamo-pituitary-adrenal axis.

BACKGROUND: Hypothalamo-pituitary-adrenal (HPA) function has been demonstrated to be compromised for weeks and even months after alcoholics cease ethanol consumption. Because nonalcoholic subjects with family history-associated increased risk for alcoholism also exhibit compromised HPA function, it is not clear whether defects in the HPA axis of abstinent alcoholics reflect a preexisting condition that may be responsible for increased risk for alcohol abuse versus a persisting adaptational change in response to prolonged alcohol abuse. Consequently, we investigated whether chronic daily ethanol consumption and withdrawal by male Sprague Dawley rats would induce persistent HPA changes consistent with those demonstrated in abstinent alcoholics. METHODS AND RESULTS: In an initial experiment in which ethanol (5%, w/v) was incrementally introduced to liquid diet over a 1 week period followed by 4 weeks of chronic ethanol consumption, not only ethanol-treated rats but also pair-fed control rats exhibited decreased (p < 0.05 vs. ad-libitum-fed controls) anterior pituitary pro-opiomelanocortin (POMC) mRNA concentrations and associated decreases in plasma corticosterone and adrenocorticotropin (ACTH) levels for at least 3 weeks after gradual withdrawal of ethanol from the diet. Pair-feeding-induced decreases (p < 0.05) in thymus and spleen weights suggested that the pair-fed controls were likely stressed in this model, probably in response to the marked and irregular suppression of liquid diet consumption immediately after introduction of ethanol. Consequently, a second model was developed in which ethanol was introduced to the liquid diet much more gradually (i.e., over 3 weeks). In contrast with the rapid ethanol-introduction model, this more prolonged ethanol introduction followed by 4 weeks of chronic daily ethanol consumption increased plasma corticosterone levels (p < 0.05), increased adrenal gland weight (p < 0.05), and decreased thymus and spleen weights (both p < 0.01) without altering any of these parameters in the pair-fed controls. Three weeks after gradual withdrawal of ethanol from the diet, anterior pituitary POMC mRNA concentrations were suppressed (p < 0.05) and thymus and spleen weights were increased (p < 0.05) versus both pair-fed and ad-libitum-fed controls, accompanied by trends for decreased basal plasma corticosterone and adrenal weights. CONCLUSIONS: Chronic daily ethanol treatment induced changes in the HPA axis that persisted for at least 3 weeks after complete cessation of ethanol consumption. These persistent alterations in the HPA axis are similar to the aberrant HPA regulation of abstinent alcoholics, sons of alcoholics, Lewis rats, and individuals who suffer from posttraumatic stress disorder and some types of depression, that is, categories of individuals who all exhibit increased risk for high ethanol consumption. Thus, these chronic daily ethanol-induced persistent changes in the HPA axis may have significant roles in alcohol abstinence syndrome and may increase vulnerability to relapse.

Adrenocorticotropic Hormone↗
PubMed1998

Psychomotor performance: investigating the dose-response relationship for caffeine and theophylline in elderly volunteers.

OBJECTIVE: The aim of the study was to investigate the dose-response relationship for psychomotor performance, caffeine and theophylline in healthy elderly volunteers. METHODS: In a randomized, double-blind, placebo-controlled, six-period cross-over study we compared the effect of three doses of theophylline (predicted peak concentrations of 3, 6 mg. 1(-1) and 12 mg . 1(-1), two doses of caffeine (predicted peak concentrations of 4.5 mg. 1(-1) and 9 mg. 1 (-1) and placebo on ten healthy elderly volunteers. Psychomotor performance was measured using a continuous attention task, symbol digit substitution test and choice reaction time. Subjective effects were assessed using visual analogue scales. Following drug administration, subjects received the test battery at 30-min intervals, up to 150 min. Maximum and mean effects from baseline on each variable were included in the analysis. RESULTS: Significant improvement on the continuous attention task was seen at the lowest concentration of caffeine and theophylline used, while at higher concentrations there was a non-significant trend towards placebo scores. There was little effect of either drug on the subjective effects measured by visual analogue scales. CONCLUSION: Caffeine and theophylline increase psychomotor performance measures of attention at low plasma concentrations in healthy elderly volunteers. This effect is not increased by higher drug concentrations and there is trend towards a return to placebo scores. The lack of effect of both caffeine and theophylline on subjective measures is consistent with previous studies of caffeine in the elderly.

Aged↗
PubMed1998

Functional imaging of the brain in the evaluation of drug response and its application to the study of aging.

Functional neuroimaging techniques including single photon emission computerised tomography (SPECT), positron emission tomography (PET) and functional magnetic resonance imaging (FMRI) can provide insight into the functional connectivity of the human brain in both health and disease, including the effects of aging and drugs on brain function. Neuroimaging measurement techniques can either be direct, using radio-specific ligands, or indirect, using the neurophysiological consequences of pharmacological interventions. Both approaches can be combined with sensorimotor or cognitive activation to examine the interaction between the targeted receptor function and the sensorimotor or cognitive process implicit in the study design. Using radionuclides, PET can provide absolute measurement of cerebral blood flow to regions of interest and can measure changes in cerebral metabolism using labelled fluorodeoxyglucose. PET offered the first opportunity to image brain activation caused by a variety of stimuli and hence to measure the effect of drugs on brain activation. PET also enables the study of drug disposition within the brain. SPECT has been used to study relative changes in cerebral blood flow associated with disease processes and also receptor occupancy. FMRI, by contrast, does not involve ionising radiation and has better spatial and temporal resolution. It is still a relatively new technique and limited by its ability to only measure haemodynamic changes through the blood oxygen level-dependent (BOLD) signal. The effects of aging on drug responsiveness and the effects of drug treatment of diseases associated with old age are relatively unexplored areas of functional neuroimaging research.

Aging↗
PubMed1998

Acute alcohol effects on opiomelanocortinergic regulation.

To assess acute effects of alcohol on forebrain and pituitary opiomelanocortinergic regulation, a model was developed in which "experienced" (previously introduced to ethanol administration, so the subjective response was not a novel stimulus) male Sprague-Dawley rats received pulsatile intragastric ethanol infusions during the dark (active) photophase to produce and sustain (for 3 hr) behaviorally relevant (0, 40 to 70, 80 to 110, or 120 to 150 mg/dl) plasma ethanol levels. The effects of alcohol on hypothalamo-pituitary-adrenal (H-P-A) axis function were biphasic with respect to dosage (inhibition with low dosage and stimulation with higher dosages) and time (initial stimulation with higher dosages was followed by rapid return to control levels even though elevated plasma ethanol levels were maintained). The effects of alcohol on H-P-A activation were also inconsistent; some of the animals did not appear to respond even though elevated (i.e., >100 mg/dl) plasma ethanol levels were produced. Induction of moderate (80 to 110 mg/dl) plasma ethanol levels acutely (within 30 min) increased immunoreactive (i) beta-endorphin concentrations in the ventral tegmental area of the brain; higher (120 to 150 mg/dl) plasma ethanol levels increased i beta-endorphin concentrations in both the ventral tegmental area and the nucleus accumbens, whereas i beta3-endorphin concentrations were not significantly altered in other brain areas. High (120 to 150 mg/dl) plasma ethanol levels also increased mediobasohypothalamic pro-opiomelanocortin (biosynthetic precursor of forebrain beta-endorphin) mRNA concentrations at 3 and 6 hr after initiation of ethanol infusions. Results demonstrate that atraumatic induction of physiologically meaningful plasma alcohol levels by gastric ethanol infusion activates the forebrain opiomelanocortinergic opioid system and exerts complex effects on the interrelated H-P-A system, consistent with evidence that these systems may interact to mediate or modulate some responses to alcohol ingestion.

Adrenocorticotropic Hormone↗
PubMed1997

Discovery and biological activity of orally active peptidyl trifluoromethyl ketone inhibitors of human neutrophil elastase.

Previously we had shown that tripeptidyl trifluoromethyl ketones (TFMKs) possessing an N-terminal diarylacylsulfonamide, such as ICI 200,880 and ICI 200,355, displayed unparalleled protection against the lung damage induced by human neutrophil elastase (HNE) when the inhibitors were administered intratracheally. Since the diarylacylsulfonamides were designed specifically to afford a long residence time in the lung, it was not unexpected that inhibitors from this class of TFMKs were not active when administered orally. Upon evaluating a large number of peptidyl TFMKs possessing a variety of N-terminal groups, several compounds were identified which demonstrated oral activity. Compounds were evaluated for their oral activity by measuring their ability to inhibit the increase in lung weight relative to body weight (Lw/Bw), the increase in red blood cells, and the increase in white blood cells induced by intratracheally administered HNE (100 micrograms/hamster). A number of tripeptidyl trifluoromethyl ketones containing neutral N-terminal groups displayed good oral activity, while those containing basic, acidic, or polar groups did not. Compound 50, possessing an N-terminal 4-(CH3O)C6H4CO group, was particularly effective, reducing Lw/Bw by 77%, red cells by 89%, and white cells by 91% when dosed at 37.5 mg/kg orally. Thus, by modifying the N-terminal group of tripeptidyl TFMKs, inhibitors can be designed which are effective in vivo when administered either orally or intratracheally.

Administration, Oral↗
PubMed1995

Health professionals and breastfeeding counseling: client and provider views.

Health care providers are the most influential and trusted source of information about breastfeeding, yet many are neither prepared nor able to provide good breastfeeding counseling to their clients. This paper reports findings on low-income mothers' and on providers' perceptions of professional breastfeeding counseling. Data collection included focus group discussions with mothers recruited from public health department clinics in the Southeast USA and who were stratified by age, parity, rural/urban residence and feeding method, and focus groups and individual interviews were conducted with health care providers from the same geographic area. The results of the study indicate a gap between the promotion and support processes for breastfeeding, and point to areas where breastfeeding counseling can be strengthened.

Attitude of Health Personnel↗
PubMed1992

A strategy for promoting breastfeeding among economically disadvantaged women and adolescents.

Best Start is an innovative social marketing approach to promote breastfeeding among low-income women. Focus group interviews were used to identify the determinants of infant-feeding decisions and the most effective strategies for encouraging women to breastfeed. Motivations and perceived barriers related to breastfeeding and social network influences on feeding choice are discussed. The findings were used to design a multifaceted breastfeeding promotion campaign aimed at new mothers, family members, health professionals, and the community at large.

Adolescent↗
PubMed1990

Serum lipid response of hypercholesterolemic men to single and divided doses of canned beans.

Dried beans lower serum lipid concentrations in healthy and hyperlipidemic subjects. To determine the effects of canned beans on serum lipid concentrations, 24 hyperlipidemic men ate one of three bean diets for 21 d in a metabolic ward. Diets A and B included 227 g canned beans (120 g beans with 107 g tomato sauce) daily, in a single dose for diet A and in a divided dose for diet B. Diet C included 182 g canned beans (162 g beans with 20 g tomato sauce) daily in a divided dose. All bean diets combined lowered serum cholesterol and triglyceride concentrations 10.4% (p less than 0.001) and 10.8% (p less than 0.025), respectively. Diet B was as effective as diet C, and the groups on those diets had greater cholesterol reductions than did the group on diet A. Serum cholesterol reduction was positively correlated (p less than 0.01) with intake of total dietary fiber and soluble fiber. The ratios of low- to high-density-lipoprotein cholesterol remained constant for all groups. Body weight decreased 1.0-1.5 kg for all groups despite constant energy intakes. Canned beans may make an important contribution to hyperlipidemia management.

Adult↗
PubMed1990

Oat-bran cereal lowers serum total and LDL cholesterol in hypercholesterolemic men.

Oat bran lowers serum lipid concentrations in healthy and hyperlipidemic subjects. To determine the effects of a ready-to-eat oat-bran cereal on lipid concentrations, we fed control (corn flakes) and oat-bran cereal diets for 2 wk to 12 men with undesirably high serum total-cholesterol concentrations. Subjects were randomly assigned to one of the two diets upon admission to the metabolic ward. After completing the first diet, subjects completed 2 wk on the alternate diet. Intakes of carbohydrate, protein, fat, and cholesterol were virtually identical on the two diets. The oat-bran cereal provided 25 g oat bran/d. The oat-bran cereal diet compared with the corn flakes diet lowered serum total-cholesterol and serum LDL-cholesterol concentrations significantly by 5.4% (p less than 0.05) and 8.5% (p less than 0.025), respectively. Final body weights on each of the diets were similar. Ready-to-eat oat-bran cereal provides a practical means to incorporate soluble fiber into the diet to lower serum cholesterol.

Aged↗
PubMed1987

Dietary fiber and diabetes: a comprehensive review and practical application.

Diabetes takes an enormous human and monetary toll each year. Current treatment too often revolves around insulin and drug therapy, neglecting diet and exercise. A comprehensive review was undertaken to assess and summarize the effects of dietary fiber on diabetes. Fiber supplement studies with guar, wheat bran, and apple fiber produced mixed results; some studies reported lowered fasting glucose and cholesterol values and less glycosuria. However, many available fiber supplements cause side effects. High-carbohydrate, high-fiber diets providing 55% to 60% of energy as carbohydrates, 15% to 20% as protein, and 20% to 25% as fat and including 50 gm or more fiber daily hold the most potential for long-term use. These diets reduce insulin requirements, improve glycemic control, lower fasting serum cholesterol and triglyceride values, and promote weight loss. Studies show good long-term adherence with these diets. Dietitians assume primary responsibility for educating individuals on the benefits and use of high-carbohydrate, high-fiber diets. Diets must be individualized, with special modifications for obesity, hyperlipidemia, or physiological states such as pregnancy and lactation. Widespread use of high-fiber diets will ultimately improve metabolic control and decrease health care costs for thousands of diabetic and non-diabetic individuals.

Adult↗
PubMed1986

Quality assessment of tetanus prophylaxis in the wounded patient.

New guidelines on tetanus prophylaxis in wound management have been prepared by the American College of Surgeons and are available in a poster format or in bulletins. The purpose of this study was to determine the impact of these educational brochures on tetanus prophylaxis in a hospital setting. The results of this study indicate that these informational brochures and posters had insignificant impact on the quality of prophylaxis against tetanus in our hospital. Innovative programs of information exchange and quality assurance are urgently needed to improve the delivery of health care.

Diphtheria Toxoid↗
PubMed1985

Efficacy of burned surface area estimates calculated from charts--the need for a computer-based model.

An accurate estimation of burn surface area is needed to correctly calculate initial fluid resuscitation, nutritional requirements, prognosis, and comparisons of treatment protocols among burn centers. The following experiment was conducted to test the accuracy of physicians compared to a computer-assisted method. Twenty-seven physicians were asked to estimate the per cent of burned surface area from an adult patient diagram. Physicians were found to consistently overestimate the percentage of burned surface area. The average physician estimate was 42% compared to 29.6% calculated by a computer-assisted program. The degree of error between physician estimates and actual TBSA burned is significant and may critically affect patient management. Additional benefits of computer assistance include a permanent record of injury, burn wound trend analysis, and meaningful statistics involving morbidity, mortality, and comparative treatment protocols among burn centers.

Body Surface Area↗