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Biomedical subjects

J Schaeffer

Publications and source records attributed to J Schaeffer.

48 records · Page 3Linked to original sources

Increasing participation and improving the quality of discussions in seventh-grade social studies classes.

An experiment was conducted to evaluate procedures to improve classroom discussions in seventh-grade social studies classes. An increased number of students participated in discussions when rules were stated for discussions, students were praised for their contributions, the teacher restated or paraphrased students' contributions aloud or on the blackboard, the teacher planned an outline of discussion questions, student contributions to discussions were recorded and were used to determine part of the students' grades for the class, and discussion grades were publicly posted.The second part of the study focused on procedures designed to improve quality of classroom discussions. Students were taught to participate in discussions by providing reasons for their statements, comparisons between different points, or examples supporting their statements. As each type of contribution was taught, recorded, and counted toward part of the students' classroom grades, each type of contribution increased. Ratings of discussions by outside judges consisting of junior high school teachers, junior high school students, and persons experienced in conducting discussions, indicated that the training increased the overall quality of the discussions. Use of the quality training procedures, however, resulted in decreased levels of overall participation in discussion, a decrease that was reversed by the use of a group contingency for participation. Finally, the discussions after training seemed to be preferred by both the teacher and the students.

Journal Article↗

Cognition and long-term use of ganja (Cannabis).

Neuropsychological variables and urine cannabinoid metabolites were evaluated in ten subjects born, raised, and educated in the United States and having histories of heavy or prolonged use of cannabis. No impairment of cognitive function was found. Cannabinoid metabolites in excess of 50 nanograms per milliliter were present in the ten urine samples. The tetrahydrocannabinol content of cannabis exceeded 8.0%.

Adult↗

Platelet free calcium concentrations measured with fura-2 are influenced by the transmembrane sodium gradient.

The influence of the transmembrane Na+ gradient on the intracellular free calcium concentration, [Ca2+]i, was studied in Sepharose gel-filtered platelets from healthy human subjects, using the Ca-sensitive fluorescent dye, fura-2. Raising the internal Na+ concentration, [Na+]i, by Na+ pump inhibition with 0.05 mM ouabain, without changing external Na+ did not cause a significant increase in [Ca2+]i. Substitution of extracellular Na+ by iso-osmolar sucrose induced a rapid (half-time about 2 min) and significant rise in [Ca2+]i; this effect was amplified in Na-loaded platelets. Partial restitution of external Na+ in these cells with increased [Ca2+]i promoted a significant and rapid Na+ concentration-dependent fall in [Ca2+]i; little decline in [Ca2+]i was observed if K+ was used instead of Na+. These observations represent in vitro evidence for the existence of a Na/Ca exchange mechanism in human platelets that may, in vivo, participate in the control of [Ca2+]i.

Benzofurans↗

Red cell cotransport activity and sodium content in black men. Relationship to essential hypertension.

Furosemide-sensitive sodium and potassium cotransport and intracellular sodium content ([Na]i) were measured in erythrocytes (red blood cells, RBCs) from a population of 90 adult black men with and without essential hypertension (EH). The mean values for sodium cotransport activity, expressed as furosemide-sensitive Na efflux (mmol/liter RBC/hr), were not significantly different among the EH patients and two control groups, normotensive subjects with a positive history (N+) and those with a negative family history (N-) for hypertensive disease (EH: 154 +/- 123, n = 53; N+: 167 +/- 93, n = 12; and N-: 207 +/- 142, n = 20; all values are means +/- SD). The mean [Na]i 9.66 +/- 3.02 mmol/liter RBC (n = 56) for the EH group was greater than the mean value for the N- control group (7.96 +/- 1.97, n = 20; p less than 0.05). The N+ group also displayed a higher mean [Na]i (10.38 +/- 3.18, n = 12; N+ vs N- p less than 0.01). Although there was substantial overlapping of [Na]i values between the groups and no clear dividing line, the distribution curve of the [Na]i values in EH was skewed toward higher concentrations than in N-. Nevertheless, we must conclude that erythrocyte cotransport and [Na]i are not clinically useful in the identification of EH in black men.

Adult↗