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Biomedical subjects

B Walker

Publications and source records attributed to B Walker.

At least 325 records · Page 18Linked to original sources
PubMedDate not supplied

Effects of some neurokinin A analogues on tachykinin-induced contraction of guinea pig trachea.

A series of analogues of neurokinin A (NKA) has been synthesized and characterized by testing for their abilities, in vitro, to contract guinea pig tracheal smooth muscle or to antagonize NKA-, NKB- and SP-induced contraction of this tissue. Substitution of NKA residues Gly8 or Leu9 by conformationally restricting amino acids produced peptides that were antagonists of NKA action, but the type and specificity of the antagonism depended on the size of the peptide. Thus, while [Ala5, Aib8, Leu10]NKA(2-10) showed no agonism and was a specific, competitive antagonist of NKA, [Ala5, Aib8, Leu10]NKA(4-10) was a noncompetitive antagonist of NKA and substance P (SP) and was itself a weak agonist at concentrations above 10(-7) M.

Amino Acid Sequence↗
PubMedDate not supplied

Diabetes update.

This article is a brief overview of the incidence, classification, and diagnosis of diabetes mellitus. Current concepts of diabetes management, including nutrition, exercise, and medication, are introduced.

Diabetes Mellitus↗
PubMedDate not supplied

Mechanisms of protection induced by attenuated simian immunodeficiency virus. IV. Protection against challenge with virus grown in autologous simian cells.

Attenuated simian immunodeficiency virus (SIV) induces potent protection against infection with wild-type virus, but the mechanism of this immunity remains obscure. Allogeneic antibodies, which arise within animals as a result of SIV infection, might protect against challenge with exogenous SIV grown in allogeneic cells. To test this hypothesis, eight macaques were infected with attenuated SIV and subsequently challenged with wild-type SIV grown in autologous cells or heterologous cells. The results clearly demonstrated that animals infected with attenuated SIV are protected against wild-type SIV grown in autologous or heterologous cells. Thus, the hypothesis that live attenuated SIV protects by the induction of allogeneic antibodies is not tenable.

AIDS Vaccines↗
PubMedDate not supplied

Role of endogenous prostaglandins in volume expansion and during furosemide infusion in conscious dogs.

The renal effects of two structurally dissimilar inhibitors of prostaglandin synthesis (Meclofenamate and RO-20-5720) were studied in conscious, chronically instrumented dogs during mild volume expansion and during a constant infusion of furosemide. When either inhibitor was administered following volume expansion, urinary excretion of PGE2 and urine flow rate were reduced by more than 50%. In contrast, renal plasma flow fell by less than 10% while glomerular filtration rate, sodium excretion, and plasma renin activity (PRA) were unchanged. In separate studies, infusion of furosemide increased renal plasma flow, urine flow rate, sodium excretion, PRA, and urinary excretion of PGE2, while glomerular filtration rate decreased. Administration of inhibitors of prostaglandin synthesis during constant infusion of furosemide reduced the urinary excretion of PGE2 to control levels, as renal plasma flow and glomerular filtration rate fell below control level. Despite these hemodynamic alterations, the furosemide-induced diuresis and increase in PRA were only partly attenuated by prostaglandin inhibition. It is concluded that in conscious dogs, intrarenal prostaglandins modulate urine flow rate during mild volume expansion and play a major role in mediating the renal hemodynamic effects of furosemide.

Animals↗
PubMedDate not supplied

Hemoglobin A1c levels in children and adolescents with diabetes mellitus.

Hemoglobin A1c (HbA1c) was measured as an indicator of glucose control in 180 children and adolescents with diabetes mellitus who received two daily injections of insulin as part of a highly structured treatment program. A total of 426 HbA1c determinations was made in the group of 180 patients. HbA1c values were elevated in most patients despite the aggressive treatment. The HbA1c level was very elevated at diagnosis, fell to near normal after 60-90 days of insulin therapy, increased gradually, and reached a plateau after approximately 4 yr duration (at about twice the level in normal subjects) (mean +/- SEM, 10.0 +/- 0.2% and 5.34 +/- 0.07%, respectively). Mean insulin dose (U/kg/24 h) paralleled both HbA1c and duration of diabetes. The relationship between endogenous insulin secretion and glucose control was examined in those patients with diabetes for longer than 5 yr. Patients were separated into three groups based on HbA1c levels: those with HbA1c less than 9% (N = 22), between 9 and 11% (N = 26), and greater than 11% (N = 28). Serum C-peptide and glucose concentrations were measured 2 h after a standard breakfast in those patients in the "low" and "high" HbA1c groups (mean HbA1c values 8.2% and 12.7%, respectively). C-peptide was detectable in all patients and the mean C-peptide levels did not differ significantly in the two groups, although postprandial glucose concentrations were significantly lower in the "low" HbA1c group (means +/- SEM, 96 +/- 11 and 211 +/- 21 mg/dl, respectively; P less than 0.001).

Adolescent↗
PubMedDate not supplied

A prospective study of symptomatic hypoglycemia in young diabetic patients.

The frequency of symptomatic hypoglycemia was determined prospectively over an 18-mo period in 147 children and adolescents with diabetes mellitus. All patients were treated with two daily injections of insulin. The data were analyzed to determine the relationship between episodes of symptomatic hypoglycemia and blood glucose control as assessed by hemoglobin A1c measurements. There were 542 patient visits during the study period. During each clinic visit, patients were separated into one of four hypoglycemic categories based on the medical history since the preceding visit. These categories were: no reactions, mild to occasional reactions, mild to frequent reactions, and severe reactions. Reactions were considered severe if they were characterized by altered central nervous system function or prolonged sympathetic nervous system symptoms. Forty-seven percent of the patients reported at least one reaction during the 18-mo study period, but only 4% (i.e., 6 out of 147 patients) reported severe reactions. The mean hemoglobin A1c level was significantly lower in patients who reported reactions than in patients who did not report reactions [hemoglobin A1c values (x +/- SEM) = 7.78 +/- 0.1% vs. 9.48 +/- 0.1%, respectively; P less than 0.001]. The severity of hypoglycemia was inversely related to the degree of altered blood glucose control; episodes of frequent or severe symptomatic hypoglycemia occurred almost exclusively in patients with well-controlled diabetes as reflected in their near-normal hemoglobin A1c levels. There were no significant differences in mean insulin dose/kg, age, or duration of diabetes comparing patients in the four hypoglycemic categories. The results indicate that the hemoglobin A1c level can be a useful clinical guide to identify patients who are most likely to develop serious symptomatic hypoglycemia.

Adolescent↗
PubMedDate not supplied

The relationship between psychological factors and blood glucose regulation in insulin-dependent diabetic adolescents.

Fifty-two insulin-dependent diabetic, white, rural, middle-class adolescent subjects who had diabetes 5 or more years participated in a project comparing psychological and personality variables to the degree of altered blood glucose regulation as measured by hemoglobin A1c (HbA1c) levels. An HbA1c level of 9.5% was arbitrarily chosen as a cutoff score to divide subjects into two groups: those having "adequate" (N = 25) and those having "inadequate" (N = 27) blood glucose regulation. There were no significant differences between high and low HbA1c groups for all psychological variables tested, i.e., anxiety, locus of control, self-concept, and various personality traits measured by the High School Personality Questionnaire (HSPQ). Female subjects scored significantly higher on the anxiety scale and had significantly higher HbA1c values and weight percentiles compared with male subjects. Six self-report diabetes questionnaires dealing with various aspects of diabetes care and adjustment were completed by mothers and five similar questionnaires were completed by the adolescents. There were no significant differences in the mean scores of the 11 diabetes questionnaires between the high and low HbA1c groups. Girls scored significantly higher than boys in "self-care" and on individual items pertaining to dysphoric feelings about diabetes. Our findings may have resulted from the homogeneity of the sample, but underlying metabolic and genetic factors need to be considered in differentiating subjects according to the level of blood glucose regulation.

Adolescent↗
PubMedDate not supplied

Legislative report.

Explore the source record for details and available documents.

Environmental Health↗
PubMedDate not supplied

The Occupational Safety and Health Act. The national policy for the prevention of work-related illness.

Occupational health and safety issues are increasingly important on the broader health agendas of both industrial and non-industrial communities. These issues go beyond traditional industrial hygiene into areas of environmental epidemiology and public health engineering. The policy framework for addressing such issues is the Occupational Safety and Health Act of 1970.

Environmental Health↗
PubMedDate not supplied

The present role of the local health department in environmental toxicology.

Environmental health concerns are focusing sharply on health risks associated with exposure to toxic substances. The local health department role in responding to these concerns is becoming more crucial as well as more difficult. Commercial production of toxic chemicals is increasing rapidly. Individuals are being exposed to these substances in their residential communities as well as in their workplaces. Over two dozen major federal laws exercise some control over toxic substances, but much responsibility for implementation rests at the local level. Local health department responsibility is primarily in the areas of education, services, and regulation. Education must be provided for local government officials and for those who render and receive local environmental services. Services must include surveillance to identify environmental causes of disease, documentation of disease and dysfunctions possibly related to toxic substances, and coordination of environmental toxicology services with related community activities. Regulatory activities call for careful risk assessment and risk management, accomplished in cooperation with other government agencies, universities, and industry.

Environmental Exposure↗