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Biomedical subjects

S Petrou

Publications and source records attributed to S Petrou.

46 records · Page 3Linked to original sources
PubMed1993

Developmental changes in the acetylcholine influence on heart muscle of Rana catesbeiana: in situ and in vitro effects.

The influence of acetylcholine (ACh) on cardiac performance of larval (Taylor Kollros [TK] stages II-XVIII) and postmetamorphic (3-609 g) Rana catesbeiana was analyzed in situ (circulatory system intact) and in vitro (isolated heart or ventricular strip preparations). Topical application of ACh to the heart in situ resulted in a dose-dependent decrease in heart rate and in a slight decrease in systolic ventricular pressure in all developmental stages. Injection of acetylcholine into the ventricle lumen in situ caused a dose-dependent transient decrease in systolic ventricular pressure, with little heart rate effect. Intraventricular ACh injection also changed the hemodynamic coupling between ventricle and conus arteriosus, generating a biphasic pressure profile in the conus due to sequential contractions of the ventricle and of the conus. In situ the sensitivity of the ventricle to ACh decreased during larval development, with the lowest sensitivity in small postmetamorphic adults. ACh applied in vitro to cardiac muscle strips or small hearts produced a negative inotropic effect. The ACh dose necessary to induce a 50% reduction in muscle strip contraction force in vitro decreased substantially during larval development, indicating an increase in ACh sensitivity with development. The effects of ACh both in vitro and in situ were diminished or eliminated by topical application or injection of atropine, suggesting the presence of muscarinic cholinergic receptors. After preincubation with the acetylcholinesterase blocker eserine, injection of ACh into the conus arteriosus decreased systolic ventricular pressure with a delay of 4-10 seconds, probably representing the minimum blood circulation time.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetylcholine↗
PubMed1993

The QALY: a guide for the public health physician.

This paper considers the background to the rational allocation of health resources at DHA level within the context of the new purchaser/provider regime. A popular approach to this problem has been that of cost utility analysis, using quality adjusted life years (QALYs) as the measure of the benefit derived from a health intervention. This paper seeks to offer the practising public health physician an appraisal of the practical value and pitfalls of a QALY-based approach. To this end, the theoretical background to QALYs and their practical use are described and some of the practical and ethical problems and pitfalls are discussed. It is concluded that the QALY concept provides a useful tool in aiding decision making in the allocation of health care resources, but that it is too early for a universal application of the approach.

Cost-Benefit Analysis↗
PubMed1992

Management of corporal veno-occlusive dysfunction.

Veno-occlusive dysfunction has become a recognized cause of organic impotence. The existence of concomitant arterial and sinus smooth-muscle disease makes this disorder often difficult to diagnose. It rarely can be the sole etiology for impotence. The authors' experience in the treatment of this disorder in over 100 patients is presented. The authors rely on cavernosometry/pharmacocavernosometry/pharmacocavernosogr aphy and the color duplex Doppler screening test (to eliminate concomitant arterial disease) as the primary diagnostic tools. Twenty-two patients of 58 (38%) have achieved long-lasting success from the surgery so that they are able to have vaginal intercourse. Another 12 patients (21%) have been improved but must depend upon pharmacological injection therapy to obtain a sufficient erection for intercourse. There has been a 41% failure rate, and these are discussed.

Arterial Occlusive Diseases↗
PubMed1979

The course of untreated mild T3 toxicosis.

A selected group of 12 patients with mild T3 toxicosis, has been assessed without treatment during a period of from seven to 38 months. Progression to typical hyperthyroidism with combined T4 and T3 excess occurred in one case of solitary toxic adenoma, while a spontaneous remission with return of the thyrotropin response to thyrotropin-releasing hormone occurred in one patient with a diffuse goitre. The other 10 patients showed persistence of isolated high levels of T3 without clinical or biochemical progression. These findings suggest that progression to typical hyperthyroidism is infrequent in mild T3 toxicosis. Because of the possible adverse effects of therapy it may be appropriate to observe, rather than treat, some patients with mild clinical and biochemical features of hyperthyroidism.

Humans↗
PubMedDate not supplied

Direct effects of fatty acids and other charged lipids on ion channel activity in smooth muscle cells.

A variety of fatty acids increase the activity of certain types of K+ channels. This effect is not dependent on the three enzymatic pathways that convert arachidonic acid to various bioactive oxygenated metabolites. One type of K+ channel in toad stomach smooth muscle cell membranes in activated by fatty acids and other single chain lipids which possess both a negatively charged head group and a sufficiently hydrophobic acyl chain. Neutral lipids have no effect on K+ channel activity, while positively charged lipids with a sufficiently hydrophobic acyl chain suppress channel activity. Acyl Coenzyme A's, which do not flip across the bilayer, act only from the cytosolic surface of the membrane, suggesting that the binding site for channel activation is also located there. This fatty acid-activated channel is also activated by membrane stretch. Moreover, this mechanical response is either mediated or modulated by fatty acids. Thus, fatty acids and other charged single chain lipids may comprise another class of first or second messenger molecules that target ion channels.

Acyl Coenzyme A↗
PubMedDate not supplied

Survival and the use and costs of hospital services for London AIDS patients treated with AZT.

The aim of this study was to evaluate the survival patterns and use and cost of hospital services of AIDS patients treated with azidothymidine (AZT) at St Mary's Hospital, London. A retrospective analysis of inpatient and outpatient case notes was performed, as was a survey of HIV-related care costs in 37 clinical departments. Of the 183 AIDS patients managed between 1 January 1987 and 30 September 1989, 132 were treated with AZt and 51 without AZT. Mean age at time of AIDS diagnosis for these predominantly homosexual men was 37.5 years for those treated with AZT compared with 40.7 years for those not on AZT. Median survival time from date of AIDS diagnosis was significantly longer for patients treated with AZT compared with those not treated with AZT (23 vs 13.5 months, P = 0.0004). The interval from diagnosis of HIV infection to date of AIDS diagnosis did not differ significantly between groups. Inpatients and outpatients use of services was greater for those receiving AZT than for those who did not. Costs reflected this increase use of services and the costs for those treated with AZT were pounds 3061 per AIDS patient-year higher compared with AIDS patients not receiving AZT; 36% of this cost was directly attributable to the cost of AZT itself. The introduction of AZT into routine clinical practice seems to have been a cost-effective intervention though it has been associated with an increased use of hospital services and associated costs per AIDS patient-year as well as increases survival time from AIDS diagnosis.

Acquired Immunodeficiency Syndrome↗