Evidence that cyclic AMP may regulate Ca2+-mobilization and phospholipases in thrombin-stimulated human platelets

The regulation of human platelet responses by cyclic AMP (cAMP) has been investigated by measuring thrombin-stimulated serotonin release, Ca²⁺ uptake and phospholipase activity. Thrombin-induced 1,2-diacylglycerol (DG) formation as a result of phospholipase C activation was inhibited by pretreatment with dibutyryl cAMP (dbcAMP) in a dose-dependent manner. Subsequent failure to produce phosphatidic acid (PA), which is converted from 1,2-DG by phosphorylation and would serve as intracellular Ca²⁺ ionophore, appeared to parallel the decrease in Ca²⁺ uptake activity. Phospholipase A₂ activity, monitored by the production of [³H]lysophosphatidylcholine and [³H]lysophosphatidylethanolamine, was also suppressed by dbcAMP. These data indicate that the intracellular cAMP level may be closely associated with Ca²⁺ uptake and phospholipases activation. In addition, it is suggested that alteration of intracellular cAMP regulates phospholipase activation and consequently platelet responses, perhaps by controlling available Ca²⁺ content.     

Thermal shock hemolysis in human red cells. I. The effects of temperature, time, and osmotic stress

Thermal shock is a form of hemolysis which occurs in human red cells exposed to greater than a critical level of osmotic stress of 1.4 Osm and subsequently cooled from above about 12 degrees C to below that temperature. Higher concentrations and higher cooling rates each increase the amount of hemolysis, within limits. Incubation for varying periods in hypertonic solutions and varying temperatures of incubation affect the amount of thermal shock. The effect of cooling rate on thermal shock is independent of the period of exposure to hypertonic solutions. Thermal shock is not the cause of freezing injury in human red cells, at least above -10 degrees C.     

Molecular cloning of the human gastrin gene.

A genomic clone that contains the human gastrin gene was isolated from a human gene library. Restriction endonuclease mapping and DNA sequencing analysis revealed that this gene is about 0.7 kb long, and has an intron. The intron is located at a position that separates the coding region into the peptide region essential for biological activities of gastrin and the non-essential, N-terminal peptide region.     

The incorporation of amino acids and nucleic acid bases into the seedling,reproductive stage and young ear portion of rice plants

Summary The incorporation of C¹⁴-amino acids (aspartic acid, glutamic acid, threonine and proline) and C¹⁴-nucleic acid bases (adenine, guanine, cytosine and uracil) into the seedling, reproductive stage and young ear portion of rice plant was investigated. It was found that C¹⁴-aspartic acid was incorporated into the rice seedling more rapidly than C¹⁴-threonine or C¹⁴-proline; on the other hand C¹⁴-proline was found to be more rapidly incorporated than C¹⁴-aspartic acid into reproductive stage plant and young ear portion. Similarly C¹⁴-adenine was incorporated into the rice seedling more rapidly than other C¹⁴-labelled bases. On the other hand C¹⁴-uracil was preferentially incorporated to C¹⁴-adenine or C¹⁴-guanine into the reproductive stage plant and young ear portion. It is suggested from the results obtained that proline is polymerized into polypeptide or protein in the rice plant more rapidly at the reproductive stage than at the seedling stage and that a higher proportion of pyrimidine bases might be involved into the metabolic process at the reproductive stage of rice plant.     

Ultrastructural detection of single-stranded DNA in rat liver nucleus by the electronmicroscopic immuno-peroxidase method

Single-stranded DNA (ssDNA) in nucleus of rat liver cell was detected electron-microscopically by an indirect immuno-peroxidase technique using anti-thymine antibody. Anti-thymine was made by immunizing a rabbit with thymine-bovine serum albumin (BSA) conjugate. Anti-thymine was prepared from anti-thymine-BSA serum by adsorption with insolubilized BSA. Immunochemical analysis of anti-thymine was performed by gel diffusion and confirmed the reactivity of antithymine with ssDNA. The enzymatic reaction products showing single-stranded DMA were detected in the chromatin areas of nuclei of both normal and regenerating rat liver cells. The specificity of the reaction product was checked by control experiments.     

Release of LH after administration of an analog of synthetic LH-RH in cattle

The $\text{in vivo}$ effect of an analog of LH-RH, (Des-Gly-NH₂¹⁰, Proethylamide⁹)-LH-RH, on LH release, was studied in one bull with azooapermia, and one cow with cystic follicle. The single intravenous injection of 100 μg LH-RH analog caused abrupt and marked increase in serum LH and the high levels of LH were maintained for 3 hours. The highest levels of serum LH were 48 and 114 times as high as the pre-treatment levels in a bull and a cow, respectively. Further studies are being undertaken to evaluate this compound for improving reproductive function in cattle.