Chromosome Specificity of Polysomy Promotion by Disruptions of the Saccharomyces cerevisiae RNA1 Gene

Previously, we showed that a disruption of the yeast RNA1 gene with LEU2 sequences promotes polysomy for chromosome XIII. Here we demonstrate that this phenotype is due to sequences specific to the RNA1 gene and that the disruption allele does not affect nondisjunction of three other chromosomes or polysomy of a minichromosome. Hence polysomy appears to be restricted to chromosome XIII.     

An immunoenzyme triple-staining method using both polyclonal and monoclonal antibodies from the same species. Application of combined direct, indirect, and avidin-biotin complex (ABC) technique

For immunohistological analysis, simultaneous detection of multiple cellular epitopes, as compared to single staining of serial sections, is sometimes needed. Therefore, immunoenzyme triple-staining protocols were tested with polyclonal and monoclonal antibodies on tissue sections and cytospin preparations. Various immunoconjugates were used in different combinations of methods, of which not all proved to be suitable. Of the tested protocols, one yielded superior results for both monoclonal and polyclonal antibodies, with optimal preservation of their original avidity. The method consists of a combination of indirect, direct, and avidin-biotin complex technique. The three antigens can be distinguished clearly and selectively by the reaction products of the enzyme activities of beta-galactosidase (green), alkaline phosphatase (blue), and horseradish peroxidase (red).     

Burkitt-type lymphoma. Diagnosis by fine needle aspiration cytology

Forty cases of lymphoma were categorized as Burkitt-type lymphoma in a study of fine needle aspiration (FNA) smears. These constituted 14.3% of all cases of non-Hodgkin's lymphoma diagnosed between 1974 and 1982. The median age was 22 years in these cases, 81.8% of which had extranodal tumors. The majority of the cells in the smears (59.8% +/- 8.32%) were in the 11 micron to 15 micron size range and 60.3% +/- 10.3% had noncleaved nuclei. An average 71% of the cells contained cytoplasmic and/or nuclear vacuolizations. Nonneoplastic macrophages were present in the smears in 87.5% of the cases. A study of paraffin-embedded sections in 17 cases revealed the characteristic "starry-sky" appearance in 11; in 5 it was not clearly appreciated and in 1 the nonneoplastic macrophages were absent. FNA cytology was found to be quite reliable for arriving at a diagnosis of Burkitt-type lymphoma. More than 50% of the cases were managed without resort to subsequent surgical biopsy. Exploratory laparotomy was avoided in 69% of the cases having abdominal tumors.     

Prostaglandins can modify gamma-radiation and chemical induced cytotoxicity and genetic damage in vitro and in vivo

The effect of prostaglandin E1, E2, and F2 alpha on gamma-radiation, benzo(a)pyrene and diphenylhydantoin-induced cytotoxicity in vivo and genotoxicity in vitro was investigated. Prostaglandin E1 prevented both cytotoxic and genotoxic actions of all the three agents, where as both PGE2 and PGF2 alpha were ineffective. In fact, it was seen that both PGE2 and PGF2 alpha are genotoxic by themselves. Gamma-linolenic acid and dihomogamma-linolenic acid, the precursor of PGE1 were also as protective as that of PGE1, where as arachidonic acid, the precursor of 2 series PGs, has genotoxic actions to human lymphocytes in vitro. These results suggest that prostaglandins and their precursors can determine the susceptibility of cells to cytotoxic and genotoxic actions of chemicals and radiation. This study is particularly interesting since, it is known that some tumor cells contain excess of PGE2 and PGF2 alpha and many carcinogens can augment the synthesis of 2 series of PGs.     

Effect of calcium overload on the phosphoinositide breakdown in the rat left ventricular papillary muscle

We investigated the effect of Ca²⁺ overload on the phospholipase C-catalyzed hydrolysis of phosphoinositides in the rat left ventricular papillary muscle. Ca²⁺ overload on the papillary muscle was induced by treatment with 0.3 mM ouabain in Ca²⁺-containing medium following either Ca²⁺-containing or Ca²⁺-free superfusion. The phosphoinositide breakdown was evaluated by determining accumulations of [³H]inositol phosphates ([³H]IPs) in the tissues prelabeled with [³H]inositol. Ca²⁺ repletion following Ca²⁺-free superfusion resulted in a rapid but small increase in resting tension that was not followed by contracture, nor was it associated with a significant increase in [³H]IPs accumulations. Treatment with ouabain following Ca²⁺-containing superfusion increased resting tension after a lag period of several minutes and produced contracture associated with an increase in [³H]IPs accumulations. The ouabain induced increases in resting tension, and accumulations of [³H]IPs were significantly potentiated by prior Ca²⁺-free superfusion instead of Ca²⁺-containing superfusion. There was a significant positive correlation between increases in resting tension and the phosphoinositide breakdown. The increased resting tension and the accumulations of [³H]IPs were not antagonized by treatments with prazosin plus atropine or indomethacin, but were abolished by superfusion with Ca²⁺-free buffer solution. Although the enhanced phospholipase C-catalyzed hydrolysis of phosphoinositides appears to be a consequence rather than a cause of increased intracellular Ca²⁺, such a biochemical change may provoke a positive feedback mechanism to develop the muscle contracture through the putative intracellular messenger action of inositol triphosphate and diacylglycerol.Abbreviations [³H]IPs [³H]Inositol Phosphates - IP Inositol Phosphate - IP₂ Inositol Bisphosphate - IP₃ Inositol Trisphosphate - PI Phosphatidylinositol - PI-4-P Phosphatidylinositol-4-phosphate - PI-4,5-P₂ Phosphatidylinositol 4,5-bisphosphate - PRZ Prazosin - ATR Atropine - INDO Indomethacin - min Minutes