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Biomedical subjects

D West

Publications and source records attributed to D West.

At least 73 records · Page 4Linked to original sources
PubMed1990

Diet in the epidemiology of gastric cancer.

We examined the nutritional epidemiology of gastric cancer in 293 cases and neighborhood-, age-, and sex-matched controls in communities throughout the counties of Niagara, Monroe, and Erie in western New York. The interview was highly detailed, requiring two and one-half hours to complete; it attempted to provide an estimate of total calories ingested as well as of macro- and micronutrients and behaviors that could affect alimentary exposures, such as the use of refrigeration. We found that risk was enhanced by sodium, fat, and retinol. Substantial reductions in risk were associated with ingestion of carotene, especially raw vegetables (including celery, cucumbers, carrots, green peppers, tomatoes, and onions), as well as with increased use of low-temperature food storage. Both refrigeration and carotene could inhibit oxidation products that could act as carcinogens in the stomach.

Adult↗
PubMed1990

Studies on the mechanism of monoclonal antibody inhibition of enzyme activity of phenobarbital-induced cytochrome P-450.

Four monoclonal antibodies (MAbs) to phenobarbital-induced cytochrome P-450 (PB-P-450) show different patterns of inhibition of PB-P-450 catalyzed aryl hydrocarbon hydroxylase (AHH), 7-ethoxycoumarin deethylase, benzphetamine demethylase and ethylmorphine demethylase. The inhibition constants vary depending on the individual monoclonal antibody and the individual substrate. Two of the four monoclonal antibodies completely inhibit the reduction of cytochrome P-450 by NADPH cytochrome c (P-450) reductase. The same cytochrome P-450 bound to carbon monoxide, however, can be reduced chemically by sodium dithionite in the presence of the monoclonal antibody. These data indicate that the two MAbs examined completely prevent electron transfer by NADPH cytochrome c (P-450) reductase. Substrate binding is partially inhibited by the monoclonal antibody. The type I substrate-binding spectrum of benzphetamine is inhibited more than the type II binding spectrum of aniline. The degree of inhibition of the substrate binding as indicated by the spectrum is less than that observed for the inhibition of catalytic enzyme activity by the monoclonal antibodies. The data indicate that each of the MAbs are directed toward epitopes on the cytochromes P-450 with different relationships to the active catalytic site.

Animals↗
PubMed1990

Mothers as effective therapists for autistic children's phobias.

Two autistic children were treated for specific fears. A three-component participant modeling procedure was implemented within a multiple baseline design across subjects. Children were exposed gradually to fearful situations, with mothers serving as therapists and reinforcers. Dependent measures were (a) number of approach steps completed, (b) frequency of verbalizations and vocalizations of fear, and (c) overall appearance of fear. Following treatment, the children functioned effectively in previously fearful situations without verbalizations or appearance of fear. Five-month and 1-year follow-up assessments with 1 child showed maintenance of treatment effects.

Arousal↗
PubMed1989

Effects of hypothyroidism on the sensitivity of glycolysis and glycogen synthesis to insulin in the soleus muscle of the rat.

1. The effects of hypothyroidism on the sensitivity of glycolysis and glycogen synthesis to insulin were investigated in the isolated, incubated soleus muscle of the rat. 2. Hypothyroidism, which was induced by administration of propylthiouracil to the rats, decreased fasting plasma levels of free fatty acids and increased plasma levels of glucose but did not significantly change plasma levels of insulin. 3. The sensitivity of the rates of glycogen synthesis to insulin was increased at physiological, but decreased at supraphysiological, concentrations of insulin. 4. The rates of glycolysis in the hypothyroid muscles were decreased at all insulin concentrations studied and the EC50 for insulin was increased more than 8-fold; the latter indicates decreased sensitivity of this process to insulin. However, at physiological concentrations of insulin, the rates of glucose phosphorylation in the soleus muscles of hypothyroid rats were not different from controls. This suggests that hypothyroidism affects glucose metabolism in muscle not by affecting glucose transport but by decreasing the rate of glucose 6-phosphate conversion to lactate and increasing the rate of conversion of glucose 6-phosphate to glycogen. 5. The rates of glucose oxidation were decreased in the hypothyroid muscles at all insulin concentrations.

Animals↗
PubMed1989

Can growth of capillaries in the heart and skeletal muscle be explained by the presence of an angiogenic factor?

Capillary growth was induced in rabbit hearts by long-term bradycardial pacing, and in skeletal muscles by long-term electrical stimulation. In order to find out what factors may be responsible for it, samples of all tissues were analysed for angiogenic activity (AA). To estimate the possible role of mechanical factors, blood flow was measured at rest and during maximal dilatation. Rabbit hearts were paced at half the normal frequency for 24 h/day for 1-2 months by electrodes implanted in the right atrium. Gastrocnemius-plantaris muscles were stimulated at 10 Hz via implanted electrodes, 8 h/day for 14 days. Unpaced hearts and non-stimulated muscles served as controls. Capillary density (estimated in frozen cross-sections stained for alkaline phosphatase) was higher in paced than in control hearts (2235 +/- 86, s.e.m. cap/mm2, 1815 +/- 83, P less than 0.005); capillary/fibre ratio was 2.84 +/- 0.21 in stimulated and 1.243 +/- 0.06 in control gastrocnemius (P less than 0.001). The presence of AA was assayed on chicken chorioallantoic membrane (CAM). All paced and 50% of control hearts showed positive CAM results. Control gastrocnemii gave positive results in 25%, plantaris in 30%: stimulated muscles showed 30% and 37.5% positive responses. Coronary blood flow at rest was significantly lower in chronically paced than control hearts (2.172 g/ml/min, 3.025 +/- 0.187, P less than 0.05) and not significantly different during maximal dilatation (9.217 +/- 1.722 and 11.166 +/- 1.158 respectively). Blood flow per heart beat was significantly higher during acute bradycardia as well as in bradycardially paced hearts at rest. Blood flow in stimulated muscles was significantly higher than in controls both at rest (26.2 +/- 3.36 ml/100 g/min as compared to 8.5 +/- 2.15, P less than 0.001) and during muscle contractions (56.1 +/- 4.5 and 20.7 +/- 2.6). It can thus be concluded that growth of capillaries in skeletal muscles may be due to mechanical factors connected with the increased blood flow while in the heart AA may act in concert with blood flow changes.

Angiogenesis Inducing Agents↗
PubMed1988

Effects of hyperthyroidism on the sensitivity of glycolysis and glycogen synthesis to insulin in the soleus muscle of the rat.

1. The effects of hyperthyroidism on the sensitivity and responsiveness of glycolysis and glycogen synthesis to insulin were investigated in the isolated incubated soleus muscle of the rat. 2. Hyperthyroidism, which was induced by administration of tri-iodothyronine (T3) to rats for 2, 5 or 10 days, increased fasting plasma concentrations of glucose, insulin and free fatty acids. 3. Administration of T3 for 2 or 5 days increased the rates of glycolysis at all insulin concentrations studied: this was due to increased rates of both glucose phosphorylation and glycogen breakdown, but there was no effect of T3 on the sensitivity of glycolysis to insulin. However, administration of T3 for 10 days increased the sensitivity of the rate of glycolysis to insulin. 4. The concentration of adenosine in the gastrocnemius muscles of the rats was not different from controls after 5 days, but it was markedly decreased after 10 days of T3 administration. If these changes are indicative of changes in the soleus muscle, the increased sensitivity of glycolysis to insulin found after 10 days' T3 administration could be due to the decrease in the concentration of adenosine. 5. Administration of T3 decreased the sensitivity of glycogen synthesis to insulin and the glycogen content of the soleus muscles. This may explain the decreased rates of non-oxidative glucose disposal found in spontaneous and experimental hyperthyroidism in man. 6. The rates of glucose oxidation did not change after 2 days, but they were increased after 5 and 10 days of T3 administration.

Adenosine↗
PubMed1988

Dietary epidemiology of cancer of the colon in western New York.

The authors interviewed 428 pathologically confirmed cases of colon cancer and controls matched on age, sex, race, and neighborhood in the New York counties containing the cities of Buffalo, Niagara Falls, and Rochester. Risk of colon cancer in both males and females, studied separately, appeared to increase with the amount of total fats and total calories ingested. In addition, we found the risk to increase with increases in the Quetelet index of relative weight (weight (kg)/height (m)2). Dietary fiber was only equivocally associated with risk. Fats and Quetelet index were associated with increased risk in a regression analysis adjusting each factor for the other, as well as for fiber, age, and socioeconomic status. The same was true for calories and Quetelet index. Future efforts to clarify a possible protective role for fiber and to disentangle the effects of fats and calories need to be undertaken. The fact that calories ingested and obesity are each associated with increased risk suggests the importance of studying calorie expenditure.

Body Height↗
PubMed1987

The aftermath of rape. Profiles of immediate and delayed treatment seekers.

Seventy-eight sexual assault victims who sought treatment within 1 month of their assaults were compared with 40 victims who delayed seeking treatment. Demographic, rape situation, and psychiatric history characteristics were examined as were postrape symptom profiles and responses to treatment. More of the delayed treatment seekers were raped by a "friend," and fewer used physical means to defend themselves against the assailant. With respect to symptomatology, delayed treatment seekers reported considerable rape-related distress and were more anxious and significantly more fearful than were recent rape victims. Implications for clinical practice and for the tailoring of services for victims of sexual assault are suggested.

Anxiety Disorders↗
PubMed1987

Diabetes insipidus with renal resistance to vasopressin in the desoxycorticosterone-treated dog: a possible role for prostaglandins.

We examined the release of vasopressin and the renal response to exogenous vasopressin before and during desoxycorticosterone acetate (DOCA) administration in the dog. As treatment with DOCA produced potassium loss, urine volume increased, urinary osmolality decreased, and urinary PGE2 tended to increase. The increase in urine volume was accompanied by increases in serum sodium, in plasma osmolality and in plasma arginine vasopressin. The threshold for vasopressin release measured during polyuria was higher than control but the rate of vasopressin release was unchanged. The DOCA-induced polyuria was not affected by treatment with vasopressin which further increased plasma vasopressin. Treatment with indomethacin which corrected the increase in urinary PGE2 excretion but not the hypokalemia, restored the renal responsiveness to vasopressin, decreased the secretion of vasopressin, and corrected the polyuria and the hypernatremia. These findings suggest that DOCA-induced polyuria is attributable to a decrease in renal responsiveness to vasopressin which may be mediated in part by an increase in the renal synthesis of prostaglandins.

Animals↗
PubMed1987

Wound healing: the effect of macrophage and tumour derived angiogenesis factors on skin graft vascularization.

Angiogenic factors prepared from rat Walker 256 mammary carcinoma, (TAF) and activated mouse peritoneal macrophages (MAF), were tested for their ability to stimulate vascularization during healing. They were applied to one of a pair of bilaterally symmetrical, autologous, isotopic, full thickness skin grafts in mice. Blood flow to treated and untreated graft pairs was compared by their uptake of injected 86Rb Cl, at 3 and 7 days after grafting. No difference was detected after treatment with either agent. We conclude that while angiogenic factors are important in vascularization during healing, this normally occurs at a near maximal rate and cannot be further enhanced.

Angiogenesis Inducing Agents↗
PubMed1986

Processing of phage T4 td-encoded RNA is analogous to the eukaryotic group I splicing pathway.

Several features of the split td gene of phage T4 suggest an RNA processing mechanism analogous to that of the self-splicing rRNA of Tetrahymena and other group I eukaryotic introns. Previous work has revealed conserved sequence elements and the ability of td-encoded RNA to self-splice in vitro. We show here that a noncoded guanosine residue is covalently joined to the 5' end of the intron during processing. Further, we demonstrate the existence of linear and circular intron forms in RNA extracted from T4-infected cells and from uninfected Escherichia coli expressing the cloned td gene. Sequence analysis of the intron cyclization junction indicates that the noncoded guanosine and one additional nucleotide are lost from the 5' end of the intron upon cyclization. This analysis places a uridine residue upstream of the cyclization site, in analogy to three other group I cyclization junctions. These striking similarities to the splicing intermediates of eukaryotic group I introns point not only to an analogous processing pathway and conserved features of cyclization site recognition but also to a common ancestry between this prokaryotic intervening sequence and the group I eukaryotic introns.

Animals↗