Search PubMed⌕ Search

Biomedical subjects

J Kaplan

Publications and source records attributed to J Kaplan.

At least 469 records · Page 26Linked to original sources
PubMed1973

Electron spin resonance studies of spin-labeled mammalian cells by detection of surface-membrane signals.

Lipid-soluble spin labels were incorporated into human lymphocytes and mouse L-cells and the resulting electron spin resonance spectra were compared with spectra obtained from similarly labeled human erythrocytes. Spin labels were found in all subcellular fractions of the nucleated cells that contained membranes. Spinlabeled cells remained viable and capable of replicating in vitro. Electron spin resonance signals from spin-labeled nucleated cells underwent a time- and temperature-dependent decay that was reversed by bathing the cells in K(3)Fe(CN)(6). The demonstration of a relative cell impermeability to ferricyanide, as measured by both colorimetric and radioisotopic label methods, indicated that only spin-labeled molecules in the surface membrane were reactivated when ferricyanide was added to spin-labeled cells after the electron spin resonance signal had decayed.

Androstanes↗
PubMed1973

Altered immune function in hypercholesterolemic monkeys.

Humoral and cellular immune responses to several antigens were compared in control and hypercholesterolemic groups of monkeys. Chronic hypercholesterolemia, with concomitant hyperphospholipidemia and hypotriglyceridemia, was produced experimentally by feeding monkeys a high-fat, high-cholesterol diet. When studied prior to infection, hypercholesterolemic monkeys exhibited impaired development of precipitating antibodies against ovalbumin, enhanced sensitivity to tuberculin antigen (stimulated apparently by mycobacterial components in complete Freund adjuvant), and an increased rate of clearance of colloidal carbon from blood. During pneumococcal infection the ability of neutrophiles from hypercholesterolemic monkeys to reduce nitroblue tetrazolium dye showed an increase greater than that of control monkeys; both groups exhibited increased but comparable final clearance rates of colloidal carbon, although the increment of increase was smaller in hypercholesterolemic monkeys.

Animals↗
PubMed1973

Task analysis in curriculum design: a hierarchically sequenced introductory mathematics curriculum.

A method of systematic task analysis is applied to the problem of designing a sequence of learning objectives that will provide an optimal match for the child's natural sequence of acquisition of mathematical skills and concepts. The authors begin by proposing an operational definition of the number concept in the form of a set of behaviors which, taken together, permit the inference that the child has an abstract concept of "number". These are the "objectives" of the curriculum. Each behavior in the defining set is then subjected to an analysis that identifies hypothesized components of skilled performance and prerequisites for learning these components. On the basis of these analyses, specific sequences of learning objectives are proposed. The proposed sequences are hypothesized to be those that will best facilitate learning, by maximizing transfer from earlier to later objectives. Relevant literature on early learning and cognitive development is considered in conjunction with the analyses and the resulting sequences. The paper concludes with a discussion of the ways in which the curriculum can be implemented and studied in schools. Examples of data on individual children are presented, and the use of such data for improving the curriculum itself, as well as for examining the effects of other treatment variables, is considered.

Journal Article↗
PubMed1972

Behavioral changes of chronic schizophrenic patients given L-5-hydroxytryptophan.

Oral administration of the serotonin precursor L-5-hydroxytryptophan with a peripheral decarboxylase inhibitor produced Mild to moderate improvement in six of seven chronic undifferentiated schizophrenic patients who were resistant to phenothiazine treatment, as compared to an oral administration of a placebo. Two of four chronic paranoid schizophrenic patients who were resistant to phenothiazine treatment became worse with 5-hydroxytryptophan, one improved. It is presumed that these psychological changes were directly or indirectly produced from increases in brain serotonin. Indirect data from animals and humans indicate that there may be an abnormality in serotonin metabolism in some schizophrenics. While our data are consistent with this hypothesis, other explanations for our data must be entertained.

5-Hydroxytryptophan↗