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Biomedical subjects

R Lewinsohn

Publications and source records attributed to R Lewinsohn.

16 recordsLinked to original sources

Medical theories, science, and the practice of medicine.

Ours is the age of science and technology. The conclusions of modern medical science and theories are derived from experimental research developed since the last century by the life sciences, with the methods of the exact and physical sciences, and the invaluable aid of technology. This paper compares past systems of medicine with our own, and examines the role of science and theory in medical practice, in the remote and recent past and at present. Has medical science and theory in the past been of benefit to medical practice? Has it helped the physician to understand disease? To treat the sick? Finally, the paper looks at a number of uncomfortable questions raised by medical practice in our own time. The widespread rejection of today's medical practice with its flawed doctor-patient relationship, its super-specialization and mechanization, and its incessantly growing reliance on technology, is examined in the light of the prodigious advances of modern medical science and some of its abuses and exorbitant claims as well as its rejection of the value of past medical systems. Our need is for an integration of the old and the new, in a synthesis that will lead us back to a more human medicine.

Greece↗

Mammalian monoamine-oxidizing enzymes, with special reference to benzylamine oxidase in human tissues.

A review is presented of the monoamine-oxidizing enzymes with special reference to the activity of benzylamine oxidase (BzAO) in human tissues. Methods of study of amine oxidases, properties (chiefly of BzAO) and some problems concerning substrate and inhibitor specificity and multiple forms of monoamine oxidase (MAO) are surveyed. The substrate specificity of human plasma BzAO is compared with that of amine-oxidizing enzymes in plasma or serum of other species. Correlations of plasma BzAO and platelet MAO activity with clinical findings are discussed. The distribution of amine oxidase activities in solid human tissues is reviewed, in particular BzAO in blood vessels and richly-vascularized tissues, as well as kinetic constants and altered patterns of activity of BzAO in human atherosclerosis. Activities of the amine oxidases in non-vascular smooth muscle, in cultured cells, and in various tissues related to human gestation, are discussed. The present knowledge of BzAO is discussed in terms of its possible clinical relevance to several human disease states, and the importance of the enzyme in the human body.

Adult↗

Monoamine-oxidizing enzymes in human pregnancy.

The activity of benzylamine oxidase (BzAO) was investigated in human maternal blood at all stages of gestation, including parturition, as well as in the puerperium. In addition, BzAO and monoamine oxidase (MAO) A and B activities were assayed in amniotic fluid, placenta, placental vessels and umbilical vessels. No correlation was found between BzAO values in maternal blood and fetal growth. Highly significant variations in maternal plasma BzAO activity were seen by the end of the first trimester, at parturition and at 6-72 h post-partum. The predominance of MAO A in placenta was again confirmed, whereas in vascular tissue and amniotic fluid, BzAO was clearly preponderant; in the latter, no MAO A activity could be detected. Placental vessels showed significantly higher MAO A activity than umbilical vessels. BzAO and what appears to be a true, soluble MAO B were demonstrated in amniotic fluid. The physiological implications of these findings are discussed.

Amniotic Fluid↗

Amine oxidase in human blood vessels and non-vascular smooth muscle.

The pattern of amine oxidation was studied in human blood vessels at various stages of development, and in tissues with muscular layers made up predominantly or exclusively of smooth muscle. Specific activity of benzylamine oxidase, present in all vascular tissues examined, was higher in vessels than in other tissue; the enzyme, in organs rich in non-vascular smooth muscle, though lower than in blood vessels, was significantly higher than in striated muscle or connective tissue. The localization of benzylamine oxidase activity in smooth muscle, as opposed to connective tissue, may have important physiological implications.

Aged↗

Amine oxidase histochemistry of the human uterus during the menstrual cycle.

The enzymes monoamine oxidase A (MAO A), monoamine oxidase B (MAO B) and benzylamine oxidase (BzAO) have been locaized histochemically in the human uterus during various phases of the menstrual cycle. The results show a large increase in MAO A activity in th endometrial gland cells in the secretory phase of the cycle. MAO B activity was found in both endometrium and myometrium but did not show a cyclical variations in activity. BzAO was localized primarily in the tunica media of the myometrial blood vessels. These observations have been supported by parallel biochemical assay.s

Benzylamine Oxidase↗

A coupled peroxidatic oxidation technique for the histochemical localization of monoamine oxidase A and B and benzylamine oxidase.

A coupled peroxidatic oxidation technique is presented which employs benzylamine and tyramine as substrates and clorgyline, deprenyl, phenelzine and pargyline as specific inhibitors. Using this technique with frozen sections of human term placenta and rat liver, the histochemical localization of monocamine oxidase A and B and bnezylamine oxidase has been demonstrated.

Animals↗

Human serum amine oxidase. Enzyme activity in severely burnt patients and in patients with cancer.

During a study of serum amine oxidase (SAO) levels in patients with fibrotic disease processes, 127 patients (100 adults and 27 children) with moderate to severe burns were investigated. Of these, 55 adults and 20 children, classified as severe, had enzyme levels of 2.7 +/- 0.3 and 4.6 +/- 0.9 McEwen Units (McE.U) (mean +/- S.E.) respectively, which, compared with those for normal healthy adults (18.3 +/- 0.6 McE.U), gave a difference of striking significance (t=21.05 for 130 d.f., and t=10.33 for 95 d.f., respectively). Subsequently, 125 patients with proven cancer were studied. 52 percent of the untreated and 41 percent of the treated showed remarkably low enzyme activity. The mean of the group of untreated patients was 9.6 +/- 1.1 McE.U, that of the treated 11.6 +/- 1.0 McE.U, and that of the entire group 10.7 +/- 0.7 McE.U. The difference between these values and normal activity is highly significant (p less than 10(-6)). Sequential SAO estimations on severly burnt patients and those with cancer established the time course of enzyme activity in these patients. Our observations suggest that estimation of SAO activity may be useful not only for the classification, monitoring and prognosis of severe burns, but also in the diagnosis of cancer and the evaluation of its treatment.

Adolescent↗

Human serum monoamine oxidase.

A study on serum monoamine oxidase (MAO) levels in fibrotic disease processes led us to investigate patients with moderate to severe burns. Strikingly low serum MAO activity was found in patients with relatively recent, severe injuries. So far, we have no explanation to offer for the phenomena observed.

Burns↗

Anaemia in mice with concomitant Schistosoma mansoni and Plasmodium berghei yoelii infection.

1. The effect on anaemia in mice given Plasmodium berghei yoelii 3 and 5 weeks after exposure to Schistosoma mansoni cercariae, was investigated. 2. Haematological criteria (PCV and haemoglobin levels), reticulocytosis, parasitaemia and splenomegaly were used as indices. 3. Anaemia was severe in the animals given P. b. yoelii and in those with mixed infection (P. b: yoelii plus S. mansoni). Malaria was found to dominate the picture until the clearance of the parasitaemia. The effect of the interaction between the diseases on the anaemia was nil. 4. Toward the end of the experiment, moderate splenomegaly was observed in the mice with mixed infection.

Anemia↗

[Chagas disease].

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Brazil↗