Effects of platelet-activating factor on single potassium channel currents in guinea pig ventricular myocytes

Platelet-activating factor (PAF) has been implicated as one of the mediators of cardiac anaphylaxis. This phospholipid has been shown to have numerous effects on a variety of tissues, including the heart. Among these effects are alterations in the resting potential and generation of arrhythmias at very low concentrations. This suggests that PAF may modulate the activity of the background, inwardly-rectifying potassium current (I_K1). Thus, the effects of PAF on I_K1 were examined at the single channel level. Ventricular cells were isolated from adult guinea pig hearts and single channel currents recorded from cell-attached patches. PAF had substantial effects on the single channel currents at sub-nanomolar concentrations (10^–11 to 10^–10 M). PAF initially caused flickering of the channels, followed by a gradual prolonged depression of channel activity. Since these potassium channels play a major role in determining the resting potential and excitability of the cardiac cell, the effects of PAF on I_K1 may play a major role in the deleterious electrophysiological actions of PAF on the heart.Abbreviations I_K1 Inwardly-rectifying background potassium current - Lyso-PAF Lyso-platelet-activating factor - PAF Platelet-activating factor     

DXS28 (C7) maps centromeric to DXS68 (L1-4) and DXS67 (B24) by deletion analysis

Complex glycerol kinase deficiency (CGKD) is a contiguous gene syndrome consisting of glycerol kinase deficiency together with Duchenne muscular dystrophy (DMD), congenital adrenal hypoplasia, and/or Aland Island eye disease. Deletion mapping of genomic DNA from patients with CGKD was carried out and allowed definitive ordering of loci DXS28 (C7), DXS68 (L1-4), and DXS67 (B24). Most reports have placed DXS68 centromeric to DXS28 and DXS67 on the basis of the initial mapping of the Iowa patient 3, but others have presented evidence consistent with the placement of DXS28 telomeric to DXS68 and DXS67. Through the use of DNA from CGKD patients with a variety of genomic deletions, this controversy is resolved and the order Xcen...DMD-DXS28-DXS68-DXS67...pter is definitively demonstrated.     

Oat Bran as a Cholesterol-Reducing Dietary Adjunct in a Young,Healthy Population

In a study to examine the effects of dietary oat bran on serum lipids, subjects who ate two oat bran muffins a day for 28 days showed a 5.3% reduction in serum total cholesterol and an 8.7% reduction in low-density-lipoprotein-cholesterol levels, while no changes were noted in subjects consuming wheat or mixed wheat and oat bran muffins. Similarly, those who ingested oat bran muffins showed an 8.3% reduction in serum triglyceride values as contrasted with an overall increase of 6.4% in the other groups combined. These findings suggest that oat bran taken daily can significantly lower serum cholesterol and triglyceride levels in a young, healthy population.     

Primer protein of bacteriophage M2 exposes the RGD receptor site upon linking the first deoxynucleotide

Summary Using electroporation with the phage PRD1 genome, we set up a high-frequency DNA transfer system for a linear dsDNA molecule with 5-covalently linked terminal proteins. The transfer was saturated when more than 100 ng of PRD1 genome was used. Electroporation efficiency was about four orders of magnitude higher than that obtained with transfection. Removal of the terminal protein abolished plaque formation, which could not be rescued by supplying the terminal protein or phage DNA polymerase or both in trans.     

Mouse Chromosome 13

Chair of Committee for Mouse Chromosome 13     

The malmö polymorphism of coagulation factor IX, an immunologic polymorphism due to dimorphism of residue 148 that is in linkage disequilibrium with two other F.IX polymorphisms

A mouse monoclonal antibody (MAB 9.9) to coagulation factor IX (F.IX) detects a polymorphism in the plasma of normal people. Its epitope has been narrowed down to <6 amino acids in the activation peptide of the X-linked F.IX protein. The activation peptide contains a dimorphism—Thr:Ala—at position 148 of the protein. Using synthetic oligonucleotides, we have demonstrated that (1) the F.IX which reacts with 9.9 has Thr at position 148 and (2) that which does not has Ala. Positive reactors (148^thr) are designated Malmö A, and negative reactors (148^ala) are designated Malmö B. The plasma levels of AA women are indistinguishable from those of A men, and both B men and BB women are null against MAB 9.9. The plasma level of Malmö A in AB women is approximately half that of AA women, and “lyonization” is clearly operating in the heterozygotes. The dimorphism is in strong linkage disequilibrium with two other intragenic RFLPs, TaqI and XmnI. Furthermore, intragenic crossing-over—including double crossing-over—appears to have occurred between the three sites. Seven of the eight possible haplotypes have been identified, five in men and two others in women. The immunoassay that identifies ～50% of the AB women in the pool of Malmö A females with 95% confidence identifies men unambiguously as A or B. The assay would be very useful for population-genetic studies of the Malmö epitope if the studies were limited to men.     

Amino acids of the Torpedo marmorata acetylcholine receptor alpha subunit labeled by a photoaffinity ligand for the acetylcholine binding site

The acetylcholine-binding sites on the native, membrane-bound acetylcholine receptor from Torpedo marmorata were covalently labeled with the photoaffinity reagent [3H]-p-(dimethylamino)-benzenediazonium fluoroborate (DDF) in the presence of phencyclidine by employing an energy-transfer photolysis procedure. The alpha-chains isolated from receptor-rich membranes photolabeled in the absence or presence of carbamoylcholine were cleaved with CNBr and the radiolabeled fragments purified by high-performance liquid chromatography. Amino acid and/or sequence analysis demonstrated that the alpha-chain residues Trp-149, Tyr-190, Cys-192, and Cys-193 and an unidentified residue(s) in the segment alpha 31-105 were all labeled by the photoaffinity reagent in an agonist-protectable manner. The labeled amino acids are located within three distinct regions of the large amino-terminal hydrophilic domain of the alpha-subunit primary structure and plausibly lie in proximity to one another at the level of the acetylcholine-binding sites in the native receptor. These findings are in accord with models proposed for the transmembrane topology of the alpha-chain that assign the amino-terminal segment alpha 1-210 to the synaptic cleft. Furthermore, the results suggest that the four identified [3H]DDF-labeled residues, which are conserved in muscle and neuronal alpha-chains but not in the other subunits, may be directly involved in agonist binding.     

Herbal medicine among the miskito of Eastern Nicaragua

Medicinal plants identified by Miskito informants in Awastara, Nicaragua, were collected in the field. They are listed and botanically identified in this paper. Particularly interesting among the collection of 23 plant species are those used to cure snakebite and athlete’s foot, as observed in the field.