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Biomedical subjects

C Bell

Publications and source records attributed to C Bell.

At least 289 records · Page 16Linked to original sources
PubMed1976

Purification of herpesvirus nucleocapsids by fluorocarbon extraction.

Purified nucleocapsids were prepared from herpes simplex virus type-1 and herpes simplex virus type-2 infected cells, using a fluorocarbon extraction technique with Freon 113. Fifty to 85% of the total nucleocapsid population remained 'nucleated' or full in terms of the nucleic acid core making them useful as a source of DNA. CsCl banded DNA represented 30--40% of the theoretical yield of the total nucleocapsid population.

Capsid↗
PubMed1975

The staging of Hodgkin's disease. Preoperative clinical assessment versus operative evaluation.

Fifty consecutive patients with the diagnosis of Hodgkin's disease, confirmed by lymph node biopsy, underwent preoperative clinical assessment and staging laparotomy between 1969 and 1974. Preoperative evaluation consisted of bone marrow examination, liver and spleen scans, intravenous pyelograms, lymphangiograms, and standard chemical laboratory tests. Operative evaluation consisted of splenectomy, liver biopsy, periaortic, mesenteric, and celiac lymph node biopsy, appendectomy, and iliac crest bone biopsy. Twenty-three patients (46 per cent) were improperly staged by preoperative clinical assessment, with twelve patients being overstaged and eleven patients being understaged. Liver and spleen scans, and intravenous pyelograms were of little value in assessing organ involvement with Hodgkin's disease. Lymphangiograms similarly were of questionable value, being interpreted as positive in twenty-one patients but histologically involved in only seven patients (overread, 67 per cent. Fourteen patients had negative lymphangiograms, with five being histologically involved (underread, 36 per cent). There was a 22 per cent incidence of pulmonary complication (atelectasis, pneumonitis) but no deaths or life-threatening complications.

Biopsy↗
PubMed1975

Vascular dopamine receptors in the canine hindlimb.

1 Increases in femoral blood flow were produced by intra-arterial injections of dopamine (5-50 mug) in some but not all anaesthetized dogs studied, following treatment with the alpha-adrenoceptor antagonist, phentolamine. 2 The dilator effect of dopamine was not due to inhibition of adrenergic vasomotor tone as it was not affected by pharmacological procedures which completely abolished the activity of vastomotor nerves. 3 Blockade of vascular beta-adrenoceptors using propanolol reduced the flow increases produced by dopamine much less than it did those produced by isoprenaline. 4 Responses to dopamine were significantly depressed by intra-arterial administration of ergometrine (0.5 mg). This dose of ergometrine did not reduce femoral dilator responses to acetylcholine, histamine, isopienaline, bradykinin, or 5-hydroxytryptamine. 5 It is concluded that the femoral vascular bed in the dog contains specific vasodilator receptors for dopamine. Ergometrine appears to be a selective antagonist of dopamine at these receptors.

Acetylcholine↗
PubMed1975

Effects of chronic oral contraceptive treatment on the conversion of angiotensin I to angiotensin II in the rat.

The effects of chronic ingestion of oral contraceptive preparations with "low" and "high" estrogen contents on conversion of angiotensin I (AI) to angiotensin II (AII) have been examined in the rat. The dosage employed was 1.0 mg/kg/day for a period of 3 to 4 weeks. Blood pressure responses in anesthesized animals showed that in vivo conversion of AI was increased by about 40% with either drug treatment. The activity of injected renin was increased to the same extent as that of AI following treatment with the low-estrogen preparation, and to a greater extent following treatment with the high-estrogen preparation. Blood pressure responses to AII were also slightly increased above control values in those animals which received high-estrogen treatment. However, conversion of AI in isolated perfused lungs or in plasma from treated rats was not significantly altered from normal. It is concluded that conversion of AI to AII can constitute the rate-limiting step in AII production under certain circumstances and that increased conversion may play a part in the changes in the renin-angiotensin system associated with high circulating estrogen levels. The increased conversion is unlikely to be due to a change in pulmonary or plasma converting enzyme activity.

Angiotensin II↗
PubMed1974

Effects of dipyridamole on neurogenic and non-neurogenic dilator responses of arterial smooth muscle.

1 In the isolated, perfused parametrial artery of the guinea-pig dipyridamole (10-100 ng/ml) potentiated dilator responses to adenosine 5'-triphosphate (ATP), glyceryl trinitrate and non-cholinergic, non-adrenergic inhibitory nerve stimulation to similar extents. In contrast dilator responses to acetylcholine were generally unaffected or reduced.2 These results support previous electro-physiological evidence that in this preparation cholinergic vasodilatation is mediated by a cellular mechanism different from that involved in the response to non-cholinergic dilator nervous activation.3 The results also suggest that potentiation of a neurally-mediated inhibitory response of smooth muscle by dipyridamole does not necessarily implicate ATP as the transmitter involved in this response.

Acetylcholine↗
PubMed1974

Ergometrine and apomorphine as selective antagonists of dopamine in the canine renal vasculature.

1 Increases in renal blood flow were produced by intra-arterial injections of dopamine (5-50 mug) in anaesthetized dogs pretreated with alpha- and beta-adrenoceptor antagonists.2 Intra-arterial administration of ergometrine (0.5 mg) or apomorphine (1 mg) produced a depression of the renal dilator responses to dopamine, without affecting renal dilatations in response to intra-arterial acetylcholine (0.1-1 mug) or histamine (2-50 mug).3 The depression of dopamine responses lasted 10-15 min, and was greater with ergometrine than with apomorphine.4 It is concluded that both ergometrine and apomorphine can be used as specific blocking agents at vascular dopamine receptors. Ergometrine is the preferred drug for this purpose.

Acetylcholine↗
PubMed1974

Release of endogenous noradrenaline from an isolated elastic artery.

1. The overflow of noradrenaline following field stimulation of vasoconstrictor nerves has been studied in isolated preparations of the guineapig thoracic aorta.2. Stimulation with trains of 3000 pulses at 5 and 25 pulses.s(-1) resulted in mean overflows of 0.15 and 0.17 (ng.g(-1)).pulse(-1) respectively.3. These overflows were not affected by pre-treatment of the aortae with the inhibitor of neuronal amine re-uptake desmethylimipramine (10(-5)M) or with the inhibitors of extraneuronal amine uptake metanephrine (5 x 10(-4)M) or desoxycorticosterone (2.5 x 10(-5)M).4. In contrast, inhibition of monoamine oxidase and catechol-O-methyl transferase with pargyline (1 x 10(-4)M) and tropolone (2.5 x 10(-4)M) caused the mean overflows to be increased to 0.27 and 0.31 (ng.g(-1)).pulse(-1) in response to stimulation at 5 and 25 pulses.s(-1) respectively. Inhibition of either enzyme alone had little effect.5. It is concluded that in the guinea-pig aorta nervously released noradrenaline is inactivated primarily by enzymic metabolism, while neural re-uptake is insignificant. This situation is the reverse of that existing in the uterine artery of the same species.6. Phenoxybenzamine (10(-5)M) also caused pronounced increases in overflow at both high and low frequencies of stimulation. This could be due to an effect of phenoxybenzamine on release of noradrenaline or on some tissue uptake mechanism distinct from the normal neuronal and extraneuronal pathways.7. Calculations based on the overflow at 5 pulses.s(-1) following total enzyme inhibition indicated that a single stimulating pulse liberated 2.1 x 10(-4) of the total transmitter store.

Journal Article↗