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Biomedical subjects

C Wright

Publications and source records attributed to C Wright.

At least 361 records · Page 20Linked to original sources
PubMed1983

Corticotrophin releasing factor is more potent than some corticotrophin-related peptides in affecting passive avoidance behaviour in rats.

The peptides corticotrophin releasing factor (CRF), ACTH4-10 and alpha-MSH have previously been shown to be behaviourally and neurochemically active. Using a passive avoidance task, we studied the effects of intra-ventricular administration of these peptides (0, 10 or 100 ng/rat) given either immediately following the learning trial, or 1 h prior to retention (24 h post-learning) test. We found that they affected behaviour; in some cases improving and in others disrupting performance. Statistical examination of the data suggests that these substances probably act on arousal mechanisms, in a manner reminiscent of the effects of vasopressin [13, 15].

Adrenocorticotropic Hormone↗
PubMed1983

A comparison of the effects of vasopressin and oxytocin with amphetamine and chlordiazepoxide on passive avoidance behaviour in rats.

On the basis of results obtained from passive avoidance studies, we have argued that the neuropeptide vasopressin could act on arousal, rather than memory processes in rats (Sahgal et al. 1982). In this report, we examine the effects of substances that are known to increase (d-amphetamine) or decrease (chlordiazepoxide) behavioural arousal, and compare the data with those obtained after vasopressin or oxytocin treatment. All four substances yielded broadly similar bimodal results (although the oxytocin data failed to reach significance). We argue for an arousal interpretation which suggests that performance and arousal are related in an "inverted-U" manner. The data also indicate that care must be taken in selecting appropriate statistical tests.

Animals↗
PubMed1983

Assessment of mitogenesis of the hormone-responsive NMU rat mammary tumor grown in culture in soft agar, using 3H-thymidine incorporation into DNA.

We have recently shown that the soft agar clonogenic assay is suitable for growing the hormone-responsive N-nitrosomethylurea (NMU) rat mammary tumor and for evaluating the factors affecting its growth. In order to improve our assessment of tumor mitogenesis beyond simple colony counting, we have validated and characterized in our system the use of 3H-thymidine (3H-ThD) incorporation of DNA. In time-course studies, we observed that in most tumors an initial peak of 3H-ThD uptake occurred on day 1 after plating followed by a decline in counts on day 2 and a second peak on day 3. 3H-ThD incorporation was markedly diminished on day 4 and 6 when maximal colony formation occurred. In experiments where NMU rat mammary tumors were plated at different cell concentrations, we observed that increasing the number of cells plated resulted in a parallel increase in counts on day 1 and colonies on day 6. Overall, a highly significant correlation was observed between 3H-ThD uptake and colony formation (r = 0.86, p less than 0.001). These results demonstrate that the 3H-ThD incorporation assay is a fast and effective method for assessing mitogenesis of hormone-responsive NMU mammary tumors grown in the soft agar clonogenic assay.

Animals↗
PubMed1983

Eucaryote thermophily: role of lipids in the growth of Talaromyces thermophilus.

The effects of growth temperature on the fatty acid composition of the phospholipids of the fungus Talaromyces thermophilus were investigated. This thermophilic organism was unable to increase the degree of unsaturation of its fatty acids when shifted from high to low growth temperatures. Inhibition of fatty acid synthesis by the antibiotic cerulenin was reversed by the addition of a mixture of palmitic, stearic, and oleic acids and ergosterol. The data obtained were consistent with the hypothesis that the thermophilic character of T. thermophilus is due to metabolic limitations that restrict its ability to regulate membrane fluidity.

Ascomycota↗
PubMed1983

Ambulatory electrocardiographic ST segment changes in healthy volunteers.

Twenty four hour ambulatory monitoring was performed on 120 healthy volunteers using a frequency modulated recorder: 50 men and 50 women below 40 years and 20 men between 40 and 60 years were studied. Twenty eight subjects had episodes of ST segment elevation (range 1-3 mm), which occurred almost invariably at night with a slow heart rate 62.4 +/- 10.4 beats/min). ST segment elevation occurred most often in men, and was not found in subjects over the age of 37. Also in 10 subjects horizontal or downsloping ST segment depression (range 1-2 mm) was recorded, usually in association with tachycardia (135 +/- 10.5 beats/min). Nine of these exercised on a bicycle ergometer, and widespread ST segment depression was observed in eight. Thus ST segment changes, which are often interpreted as myocardial ischaemia in patients with ischaemic heart disease, are commonly seen in 24 hour electrocardiographic monitoring of healthy volunteers.

Adult↗
PubMed1983

Effect of tamoxifen and alpha-difluoromethylornithine on clones of nitrosomethylurea-induced rat mammary tumor cells grown in soft agar culture.

N-Nitrosomethylurea-induced mammary tumors were grown in a bilayer soft-agar culture system. The antiestrogen tamoxifen prevented formation of 50% of colonies formed in this in vitro system. Possible mediation of these antimitotic effects through the polyamine pathway was suggested by a similar inhibition of colony formation by difluoromethylornithine (DFMO), a suicide inhibitor of ornithine decarboxylase, and the lack of additivity of DFMO and tamoxifen. The cytostatic effect of DFMO was found to be dose dependent. The specificity of the DFMO effect through the polyamine pathway was indicated by the dose-dependent rescue of colony growth with exogenous administration of putrescine, the polyamine distal to the site of inhibition. A lack of alteration of colony size in proliferating clones was uniformly observed. These data indicate that the soft-agar culture technique can be successfully used to investigate the endocrine mechanisms affecting the growth of individual experimental mammary cancers. The data also suggest an important role of polyamines in mediating the growth of this mammary tumor model.

Agar↗
PubMed1983

Teaching health.

Explore the source record for details and available documents.

Health Promotion↗
PubMed1982

Failure of vasopressin to enhance memory in a passive avoidance task in rats.

Several authors have suggested that the neurohypophysial hormone arginine-8-vasopressin (AVP) facilitates both the consolidation and the retrieval of memory. This conclusion has relied mainly on the finding that AVP increases the latency of re-entry into a box where shock has previously been encountered, that is, in a passive avoidance task. Our results do not support this interpretation. On the contrary, we found that post-trial, intraventricular (i.t.) administration of AVP (1 ng in 1 microliter) produced relatively short as well as long latencies (a bimodal effect), suggesting that the peptide acts on motivational processes, for example by increasing arousal.

Animals↗
PubMed1982

Effects of gluten on schizophrenics.

Previous studies have suggested that a cereal- and milk-free diet may be beneficial to schizophrenics and that the gluten in regular diets is harmful to schizophrenics. In an effort to replicate these findings, with improved control vehicles, patients on a locked ward were placed on a cereal- and milk-free diet. Thirteen schizophrenics were given gluten-free peanut-flour supplementary cookies and 13 were given virtually identical cookies with gluten added. Tests and rating scales before and after the ten-day study period showed no greater improvement for those receiving the gluten-free cookies than for those receiving the gluten-added cookies. Contrary to expectations, the group receiving gluten-added cookies showed significantly greater improvement of Profile on Mood States measures of tension-anxiety and anger-hostility. Previous findings were not supported. Perhaps a longer time on the diet is required for any beneficial effects to appear.

Adolescent↗
PubMed1981

The relationship between twelve-month home stimulation and school achievement.

Home Observation for Measurement of the Environment (HOME) was designed to reflect parental support of early cognitive and socioemotional development. 12-month HOME scores were correlated with elementary school achievement, 5--9 years later. 50 low-income children were rank ordered by a weighted average of centile estimates of achievement test scores, letter grades, and curriculum levels in reading and math. 24 children were classified as having significant school achievement problems. The HOME total score correlated significantly, r = .37, with school centile scores among the low-income families. The statistically more appropriate contingency table analysis revealed a 68% correct classification rate and a significantly reduced error rate over random or blanket prediction. The results supported the predictive value of the 12-month HOME for school achievement among low-income families. In an additional sample of 21 middle-income families, there was insufficient variability among HOME scores to allow prediction. The HOME total scores were highly correlated, r = .86, among siblings tested at least 10 months apart.

Achievement↗