Comparative informative value of chromosome aberrations and sister chromatid exchanges in the evaluation of metals in the environment

The effects of met-enkephalin, leu-enkephalin, D-Ala2-metenkephalin, and somatostatin on Wenckebach arrhythmia and atrioventricular dissociation was investigated in experiments on anesthesized cats. Arrhythmias were induced by stimulation of the vagus with short repetitive bursts of pulses. Enkephalins evoked a protective effect in both arrhythmias whereas somatostatin had no antiarrhythmic properties. The protective effect of enkephalins persisted after blockage of mu-opiate receptors with naloxone (0.2 mg/kg), but in high doses (2 mg/kg), which blocked both mu- and delta-opiate receptors, antiarrhythmic effects was abolished. It is concluded that the protective effect of enkephalins against vagally induced arrhythmias may be due to the stimulation of delta-opiate receptors located on the presynaptic vagal endings. As a results, stimulation-evoked acetylcholine release is diminished, which prevent the arrhythmogenic effect of the vagus nerve.     

A novel molecular determinant for cAMP-dependent regulation of the frog heart Na+-Ca2+ exchanger

Na+-Ca2+ exchanger is one of the major sarcolemmal Ca2+ transporters of cardiac myocytes. In frog ventricular myocytes the exchanger is regulated by isoproterenol via a beta-adrenoreceptor/adenylate-cyclase/cAMPdependent signaling pathway providing a molecular mechanism for the relaxant effect of the hormone. Here, we report on the presence of a novel exon of 27-base pair insertion, which generates a nucleotide binding motif (P-loop) in the frog cardiac Na+-Ca2+ exchanger. To examine the functional role of this motif, we constructed a full-length frog heart Na+-Ca2+ exchanger cDNA (fNCX1a) containing this exon. The functional expression of fNCX1a in oocytes showed characteristic voltage dependence, divalent (Ni2+, Cd2+) inhibition, and sensitivity to cAMP in a manner similar to that of native exchanger in frog myocytes. In oocytes expressing the dog heart NCX1 or the frog mutant (DeltafNCX1a) lacking the 9-amino acid exon, cAMP failed to regulate Na+-dependent Ca2+ uptake. We suggest that this motif is responsible for the observed cAMP-dependent functional differences between the frog and the mammalian hearts.     

Use of polyethylene glycol for the microinjection of exogenous protein into cultured murine cells

Polyethylene glycol was applied to microinject two exogenous proteins: bovine serum albumin and non-histone protein derived from mouse spleen chromatin, into the mouse L-cells. The effectiveness of fusion of mammal (human, in the given case) erythrocytes in which hemoglobin is substituted for the protein under study was shown to be higher than when Sendai virus was used. The microinjected proteins preserve their specificity to subcellular structures.     

Genetic control of isolating mechanisms in the genus Drosophila]

Published data on the genetic control of isolating mechanisms in the genus Drosophila are discussed. The main isolation types of genetic mechanisms (ecological isolation, behavioral isolation, hybrid sterility, and the inviability or impaired development of interspecific hybrids) are considered. It is shown that each of the isolation barriers between different species is controlled by a small number of genes. However, as each pair of sibling species is usually separated by several barriers, the total number of isolation genes is about 20 to 30. The probable sequence of events in the appearance of isolation barriers during the divergence of novel species is discussed. A concept of the consolidation of a new species is proposed. This concept is based on the assumption of the genetic determination of behavior that promotes crossing between individuals of the new genotype and constrains their crosses with individuals of the ancestral genotype.     

Successful salvage using mismatched umbilical cord blood transplant in an adult with recurrent acute myelogenous leukemia failing autologous peripheral blood progenitor cell transplant: a case history and review

OBJECTIVE: To investigate the relationship between asthma and obesity in children and adolescents. DESIGN: Medical record review. SETTING: Urban community health center. PARTICIPANTS: One hundred seventy-one children aged 4 to 16 years, 85 with asthma and 86 nonasthmatic controls. MAIN OUTCOME MEASURES: Diagnosis of asthma, age, and sex-adjusted body mass index (weight in kilograms divided by the square of the height in meters). RESULTS: Seventy-eight percent of the sample was Hispanic, 17% was African American, 2% were white, and 3% were other minorities. There were significantly more children with asthma (30.6%) who were very obese (> or =95th body mass index percentile) compared with controls (11.6%) (P=.004). Children with asthma were also significantly more overweight than controls (mean+/-SD, 22.5%+/-28.3% vs 12.0%+/-19.6% overweight; P=.004). The difference in obesity between children with asthma and controls was significant for both sexes and across the 4.5 to 10.9 years and 11 to 16 years age groups. Asthma severity was not related to obesity. CONCLUSION: Asthma is a risk factor for obesity in children and adolescents.