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Biomedical subjects

A Dawson

Publications and source records attributed to A Dawson.

At least 163 records · Page 9Linked to original sources
PubMed1982

Conditioned medium increases the rate of neurite elongation: separation of this activity from the substratum-bound inducer of neurite outgrowth.

Heart cell-conditioned medium supports extensive neurite outgrowth from dissociated parasympathetic neurons of the chicken embryo ciliary ganglion. We have shown previously that neurite outgrowth in this system depends on the deposition of a substratum-conditioning factor from conditioned medium onto the polyornithine culture substratum. However, in the presence of only the substratum-bound material, neurite outgrowth is never as extensive as in whole conditioned medium. The present report demonstrates that a different and soluble component of conditioned medium is required to achieve the rates of neurite elongation normally observed in whole conditioned medium. This second component, while unable by itself to support neurite outgrowth, is able to increase the rate of neurite elongation approximately 3-fold within 30 to 60 min of its addition. This conclusion is based on direct time-lapse observations of the rate of elongation of individual neurites before and after the addition of fractions of conditioned medium previously depleted of the substratum-conditioning factor. Correlated with the effect of such fractions of conditioned medium on the rate of neurite elongation is a change in the morphology of the growth cones, which become larger and more spread. The activity of the soluble, elongation-promoting component of conditioned medium is nondialyzable and is sensitive to treatments known to affect proteins, such as repeated freeze-thawing, heating, and trypsinization. Fractions of conditioned medium which contain the elongation-promoting activity also contain all of the survival factor for parasympathetic neurons previously shown to be present in heart cell-conditioned medium. The methods described here represent a convenient new assay which we have used recently to demonstrate elongation-promoting factors with neuronal specificity in extracts of rat hippocampus.

Animals↗
PubMed1981

Cell cultures and their use in drug sensitivity prediction.

This paper reviews briefly the advantages of in vitro methods for predictive drug sensitivity testing and then summarizes the present situation. Clear evidence of variation in chemosensitivity at the cellular level is now available, the value of the test for predicting in vivo resistance is confirmed, and some evidence that treatment of advanced carcinoma of the ovary on the basis of a predictive test prolongs survival is presented. Ways in which the laboratory test might be improved are suggested and outstanding clinical problems, in particular the need for a very large number of patients in any prospective trial designed to detect a small improvement in treatment, are discussed.

Antineoplastic Agents↗
PubMed1979

A comparison of the effects of labetalol, bendrofluazide and their combination in hypertension.

1 Bendrofluazide (10 mg/day) or labetalol (300 mg and 600 mg/day) produced significant reductions in lying, standing, and post-exercise blood pressure in ten hypertensives. 2 Active treatments were approximately equivalent in anti-hypertensive effect. However, comparing lying and standing determinations, labetalol (600 mg/day) produced significantly greater additional postural falls in systolic blood pressure than during placebo or bendrofluazide treatment. 3 Systolic blood pressure rose after exercise during placebo or bendrofluazide treatment. However, on labetalol, mean changes in systolic blood pressure after exercise were negative and significantly different from those seen on placebo. 4 Greater reductions in lying and post-exercise systolic blood pressure were produced by combination treatment than by either individual drug. Additional postural and exercise-related falls in systolic blood pressure tended to be smaller with combination treatment than during treatment with labetalol alone. 5 Labetalol significantly reduced lying, standing, or post-exercise heart rate by comparison with placebo or bendrofluazide. 6 Labetalol significantly reduced lying, standing, or post-exercise heart rate by comparison with placebo or bendrofluazide. 6 Labetalol moderately reduced plasma renin activity, whereas bendrofluazide caused marked elevation. The effect of bendrofluazide predominated during combination treatment.

Adult↗
PubMed1977

Electron spin resonance as a useful technique in the management of Hodgkin's disease.

Electron spin resonance spectroscopy has proved a useful and simple technique for the measurement of levels of caeruloplasmin and iron transferrin in whole blood from 50 patients with Hodgkin's disease. Those patients with clinically active disease show higher caeruloplasmin levels and lower iron transferrin levels than those with inactive disease. The results indicate that these tests are good indicators of the state of the disease and that serial measurement of these parameters may help in early prediction of clinical reactivity and in monitoring response to treatment. The combined information from iron transferrin and caeruloplasmin levels appears to be more predictive than that from the erythrocyte sedimentation rate and neutrophil alkaline phosphatase score.

Adolescent↗
PubMed1977

Electron spin resonance measurements of blood caeruloplasmin and iron transferrin levels in patients with non-Hodgkin's lymphoma.

Caeruloplasmin and iron transferrin level were measured in blood of patients with non-Hodgkin's lymphoma in different stages of disease activity and compared with erythrocyte sedimentation rate and NAP level in the same samples. It was found that both caeruloplasmin level and sedimentation rate showed a slight increase in mean level in patients with active disease as compared with those in remission, particularly in the group of patients with poorly or undifferentiated diffuse disease. No difference was observed in levels of iron transferrin or NAP. Both caeruloplasmin and sedimentation rate showed occasional abnormal values in patients in remission but in most cases where both were elevated the patients subsequently entered a more active phase of the disease.

Adult↗
PubMed1977

The transient anti-hypertensive effect of phentolamine in patients receiving beta-blocker treatment.

In seven hypertensives receiving beta-blocker drugs, and additional reduction in standing blood pressure occurred between 60 and 90 minutes after 40 mg phentolamine by mouth. The occurrence of the postural hypotensive effect was delayed in relation to the reported time of peak plasma concentration of unchanged phentolamine. Supine blood pressure and heart rate were unaffected. Phentolamine has no clinically useful anti-hypertensive effect in conjunction with beta-blockers in patients with essential hypertension.

Adult↗
PubMed1976

Cell kinetics of a chondrosarcoma.

The cell kinetics of the transplantable DC-II mouse chondrosarcoma have been studied by the pulse labelled mitoses method. The analysis gave the following estimates for the phases of the cell cycle: G1, 10-5 hr; S, 9-5 hr; G2, 4 hr with an intermitotic time of 23-5 hr. Consideration of the overall growth of the tumour indicated that the growth fraction and cell loss factor both had values of about 0-5. The results are compared with cell kinetic data from sarcomas and other cartilage tissues.

Animals↗
PubMed1976

Interrelations between ABO blood group, plasminogen, alpha1-antitrypsin, alpha2-macroglobulin and the platelet count in blood donors.

The level of plasminogen alpha1-antitrypsin, alpha2-macroglobulin and the platelet count were measured in 511 blood donors. The mean level of alpha1-antitrypsin was significantly lower in men of group B compared with that of group O. No other differences between the blood groups reached statistical significance. Woman had higher mean levels of alpha1-antitrypsin and alpha2-macroglobulin and a higher platelet count than men. The levels of plasminogen and alpha1-antitrypsin were significantly higher in women using oral contraceptive compared with those who were not. The level of alpha2-marcoglobulin fell with age until the 60-64 year age-group in men and the 40-49 year age-group in women. A positive correlation existed between the alpha1-antitrypsin and the alpha2-macroglobulin level and between the platelet count and the plasminogen level.

ABO Blood-Group System↗
PubMed1976

Regional lung function in chronic pulmonary congestion with and without mitral stenosis.

Relative regional ventilation and perfusion were measured with xenon-133 in 16 seated patients with pure or predominant mitral stenosis (group 1) and in 12 patients with chronic pulmonary congestion due to left-sided heart disease without mitral stenosis (group 2). The apex-base perfusion gradient was abnormally reduced and often reversed in group 1 patients. There was a significant negative correlation between perfusion gradient and mean pulmonary capillary pressure in both groups, but for a given elevation of pulmonary capillary pressure the perfusion gradient tended to be greater (i.e., less abnormal) in group 2. The regression line of perfusion gradient on pulmonary capillary pressure indicated that perfusion gradient had a value of zero (indicating reversal of the perfusion gradient) at a mean pulmonary capillary pressure of 26 mm Hg in group 2 but at only 18 mm Hg in group 1. Relative lower zone ventilation was abnormally reduced in group 1 and there was a significant negative correlation between ventilation gradient and pulmonary capillary pressure in group 1 but not group 2 patients. Comparison of the distribution of slowly inhaled small volume boluses, large volume boluses, and inspiratory capacity breaths of 133Xe suggested that the lower zone hypoventilation was due mainly to closure of peripheral airways but that selectively increased resistance and reduced compliance in the lower zones may contribute in some patients. Both ventilation and perfusion were reduced at the lung bases in group 1 patients, and between regions nonuniformity of relative ventilation/perfusion was significantly less than normal. Although ventilation distribution was relatively normal in group 2 patients, they also had significantly less regional ventilation/perfusion nonuniformity than normal subjects.

Adult↗
PubMed1974

Assessment of an in vitro screening test of cytotoxic agents in the treatment of advanced malignant disease.

The value of a screening test for sytoxic chemotherapeutic agents in the treatment of advanced malignant disease is assessed by comparing the performances of 32 patients whose treatment followed closely the test recommendations with that of 31 patients whose treatment did not follow the predictions. The significant improvement in short-term prognosis (p=0.004) indicates that the test is of clinical value. The limitations of retrospective analysis are discussed in detail.

Adult↗