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Biomedical subjects

C L Johnson

Publications and source records attributed to C L Johnson.

At least 199 records · Page 11Linked to original sources
PubMed1977

Attitudes toward parenting in dual-career families.

The authors interviewed 28 dual-career families with young children and found that the wives and mothers in particular experience difficulties in respect to the proliferation of role demands in both home and job situations. The greatest strain was in the maternal role; guilt and anxiety were prominent. The literature is reviewed, techniques used by dual-career families to resolve role strain are discussed, and suggestions are made for the clinician's role as facilitator for reducing role strain among career mothers.

Adaptation, Psychological↗
PubMed1977

The interaction of histamine and guanylnucleotides with cardiac adenylate cyclase and its relationship to cardiac contractility.

Histamine stimulates adenylate cyclase activity in a washed membrane preparation from guinea-pig ventricle. Marked synergistic effects are observed with histamine and GTP. In the absence of GTP, the degree of stimulation of the enzyme by histamine is slight and occurs only in the presence of relatively high concentrations of ATP suggesting that ATP, or contaminating GTP in commercial preparations of ATP, may partially satisfy the guanylnucleotide requirement. The GTP analog, GppNHp, strongly and irreversibly activates the cardiac enzyme. Preincubation studies, in which the membranes are treated with GppNHp alone or in combination with histamine followed by estensive washing, indicate that histamine markedly increases the rate of activation of the enzyme by the guanylnucleotide. It is suggested that the mechanism of action of histamine on adenylate cyclase involves a facilitation of the interaction of guanylnucleotides with the regulatory site of the enzyme. The relative activities for stimulation of adenylate cyclase of a series of histamine analogs correlate quite well with the activities of these derivatives on four H2-receptor systems, including atrial rate and ventricular contractility and do not correlate with the activities on H1-receptors. The H2-receptor antagonists, burimamide and metiamide, competitively inhibit hitamine-stimulated adenylate cyclase and the dissociation constants for these antagonists on the enzyme agree with the pharmacological data on the H2-receptors in the atria and ventricles. Our results suggest that histamine-stimulated cardiac adenylate cyclase can be classified inotorpic and chronotropic effects of histamine on the intact heart.

Adenylyl Cyclases↗
PubMed1977

Comparison of the daily endogenous faecal magnesium excretion from sheep eating grass with high sodium or high potassium concentrations.

Metabolism trials were conducted with two sheep to determine the daily endogenous faecal magnesium excretion and the true magnesium availability of grass which had either a high potassium or a high sodium content. The experiment was conducted as a simple cross-over design and the isotope dilution technique using 28Mg was employed. The sheep ate sodium fertilised grass containing 0-73 per cent Na and 1-55 per cent K and potassium fertilised grass containing 0-15 per cent Na and 3-12 per cent K in the dry matter. The daily endogenous faecal magnesium excretion was not found to be significantly different for each sheep on both grasses; this excretion was approximately 13 per cent of the total faecal magnesium output. The true availability of magnesium was greater in the sodium fertilised grass than in the potassium fertilised grass. It was concluded that the daily endogenous faecal magnesium excretion was not affected by altering the herbage levels of sodium and potassium.

Animal Feed↗
PubMed1976

Quantitative structure-activity studies on monoamine oxidase inhibitors.

Quantitative structure-activity studies were carried out on a series of N-isopropylaryl hydrazides which inhibits monoamine oxidase (MAO). The inhibitory potencies of these compounds of MAO were found to correlate with the electron-withdrawing capacity of the aryl ring substituents as estimated by both empirical Hammet sigma constants and electronic indices from molecular orbital calculations. Based on these correlations and previously published data on other classes of MAO inhibitors, a general model for the inhibitor pharmacophore is proposed: potent MAO of an aromatic ring; electron-withdrawing groups on the aromatic ring or replacing the phenyl ring with certain types of heterocyclic rings will tend to increase the potency.

Hydrazines↗
PubMed1976

Treatment of lumbar disks with chymopapain.

Symptoms arising from a herniated disk appear when the nucleus pulposus or soft inner portion of the disk bulges against a nerve root. When conservative treatment fails to help the patient, the enzyme chymopapain is currently being used in the treatment of such conditions. Injected directly into the disk, the chymopapain dissolves the nucleus by enzymatic action which selectively breaks certain bonds within the nucleus. The pressure within the center is decreased, hence the pressure against the nerve root is relieved, alleviating the symptoms. Because back care is particularly important following such treatment, physical therapy is valuable in promoting continued relief. The major emphasis of the therapy back care program is on abdominal strengthening exercises and postural training.

Chymopapain↗
PubMed1975

Citrate uptake in membrane vesicles of Klebsiella aerogenes.

In whole cells of Klebsiella aerogenes grown anaerobically on citrate as sole carbon source, citrate uptake is followed by rapid catabolism of the substrate via the inducible citrate fermentation pathway. Membrane vesicles prepared from such cells take up citrate but do not catabolize it. Vesicles process d-lactate dehydrogenase and the Na+-requiring oxalacetate decarboxylase. Citrate is taken up in the presence of Na+, and other monovalent cations, such as NH4+, Rb+, Cs+, or K+, do not substitute for Na+. Li+ appears to act synergistically with Na+. Citrate uptake is inhibited by N-2, cyanide, azide, sulfhydryl reagents, dinitrophenol, fluorcitrate, and hydroxycitrate.

Anaerobiosis↗
PubMed1975

Lamellation of the diploe in the skulls of patients with sickle cell anaemia.

This study describes the radiological and pathological findings in a necropsy series of 70 skulls of Nigerian patients with sickle cell gene, and 70 controls matched for sex and age with no sickle cell gene. 6 (35%) of the 17 patients with sickle anaemia, or 17% of 35 patients with sickle cell gene excluding the trait, all under age 10 years, were shown to have bone trabeculae within the diploe arranged in stripes parallel to the curvature of the cranial tables on radiography. Histological examination of the skulls with curvilinear stripes showed long trabeculae of bone within the diploe similarly arranged in parallel rows but joint at variable intervals by short bridges of bone. The radiolucent areas between trabeculae corresponded to areas of marrow hyperplasia. A skull radiograph in an African child presenting with this radiological sign should raise the suspicion of sickel cell disease.

Adolescent↗