4-Aminopyridine affects synaptosomal protein phosphorylation in rat hippocampal slices

Rat brain hippocampal slices were incubated with or without the convulsant 4-aminopyridine (4-AP). From these slices a crude mitochondrial/synaptosomal membrane fraction was prepared and analyzed for endogenous protein phosphorylation. 4-AP (10(-5) M) stimulated the phosphorylation of a 50 kDa protein by 86%. The phosphorylation of this 50 kDa protein is Ca2+/calmodulin-dependent and we suggest that this protein is the lower molecular weight subunit of Ca2+/calmodulin-dependent protein kinase II (CaMK II).     

Levels of metals in hair of young children as an indicator of environmental pollution

In 1982 the levels of lead (Pb), cadmium (Cd), vanadium (V), copper (Cu), and selenium (Se) were determined in hair of 231 four- to five-year-old children. The objective was to explore the feasibility of using metal-in-hair levels in groups of children as an indicator of environmental pollution. The study was carried out in four areas, which were assumed to differ in ambient pollution by metals. A questionnaire on personal data, socioeconomic status, intake of beverages, and life-style was completed by the parents. The metal-in-hair levels covered a large range. The variables pertaining to location together with sex, presence of a garden, and drinking of coffee and/or tea explained 32% of the variance of Pb, 24% of the variance of Cd, and 21% of the variance of V. The total variance explained by all measured questionnaire items was at best 38%. The location was the most important factor. Cu and Se levels did not differ between the locations.     

Actions of phencyclidine on the action potential and membrane currents of single guinea-pig myocytes

The direct actions of phencyclidine (PCP) on mammalian sarcolemma were examined by determination of the drug's effects on the action potentials of isolated guinea-pig ventricular cells, and on the underlying ionic currents. PCP (10(-6) to 10(-4) M) did not alter the resting membrane potential but produced a dose-dependent prolongation of the duration of the action potential, and a reduction of the rate of depolarization of phase 0 (Vmax) of the action potential. Voltage clamp experiments revealed that PCP blocks both myocardial Ca++ channels and myocardial time-dependent K+ channels. The K+ channel blockade was shown to exhibit an apparent voltage-dependence. The effects of PCP on these ionic channels could explain previous reports of it prolonging myocardial action potentials and conflicting reports of positive and negative inotropism.     

Association between human IgM autoantibodies and kappa chain allotypes

The relationship between the immunoglobulin kappa light chain allotypes and autoantibodies was studied in a series of seven human monoclonal kappa-bearing IgM antibodies with Rheumatoid Factor (RF) activity, two IgM anti-low density lipoprotein (LDL) antibodies, and one IgM anti-intermediate filament (IF) antibody. Residues at amino acid positions 153 and 191 related to the Km allotypes in human kappa chains were determined by an HPLC tryptic fingerprint and corroborated by amino acid sequence analysis. All the autoantibodies shared similar variable regions derived from the V kappa IIIb gene(s). The seven RF and the anti-IF were associated with the Km(3) constant region allotype whereas the two anti-LDL were associated with the Km(1,2) allotype. Thus, monoclonal autoantibodies showed the same Km allotypic distribution as the normal population. However, although the number of samples is small, it seems likely that a preferential association may exist between particular V kappa genes and Km alleles in the generation of autoantibodies with different specificities.     

Renal stone analysis: LITHOS, an expert system for evaluation of X-ray diffractograms of urinary calculi

An expert system for evaluation of X-ray diffraction patterns of urinary calculi is described and evaluated. The software was developed using the PERSONAL CONSULTANT expert system shell from Texas Instruments.