Biomedical subjects

S G Spitzer

Publications and source records attributed to S G Spitzer.

22 records · Page 2Linked to original sources

PubMed1986

Assembly in an in vitro splicing reaction of a mouse insulin messenger RNA precursor into a 60-40S ribonucleoprotein complex.

An SP6/mouse insulin RNA precursor containing two exons and one intron can be spliced in a partially purified nuclear extract isolated from MOPC-315 mouse myeloma cells. We have detected the putative RNA splicing intermediate (intron-3'exon) in a lariat form, the excised intron in a lariat form, and the mRNA spliced product. The in vitro splicing reaction of gel-purified RNA precursors requires ATP and Mg2+ and was accompanied by the formation of a 60-40S ribonucleoprotein complex. The formation of the 60S complex requires ATP. At least two Sm snRNPs containing U1 and U2 RNAs are components of the 60-40S complex. The assemble of those snRNPs occurs early during the splicing reaction and it requires ATP and intron containing pre-mRNAs.

Adenosine Triphosphate↗

PubMed1986

Endonuclease IV (nfo) mutant of Escherichia coli.

A cloned gene, designated nfo, caused overproduction of an EDTA-resistant endonuclease specific for apurinic-apyrimidinic sites in DNA. The sedimentation coefficient of the enzyme was similar to that of endonuclease IV. An insertion mutation was constructed in vitro and transferred from a plasmid to the Escherichia coli chromosome. nfo mutants had an increased sensitivity to the alkylating agents methyl methanesulfonate and mitomycin C and to the oxidants tert-butyl hydroperoxide and bleomycin. The nfo mutation enhanced the killing of xth (exonuclease III) mutants by methyl methanesulfonate, H2O2, tert-butyl hydroperoxide, and gamma rays, and it enhanced their mutability by methyl methanesulfonate. It also increased the temperature sensitivity of an xth dut (dUTPase) mutant that is defective in the repair of uracil-containing DNA. These results are consistent with earlier findings that endonuclease IV and exonuclease III both cleave DNA 5' to an apurinic-apyrimidinic site and that exonuclease III is more active. However, nfo mutants were more sensitive to tert-butyl hydroperoxide and to bleomycin than were xth mutants, suggesting that endonuclease IV might recognize some lesions that exonuclease III does not. The mutants displayed no marked increase in sensitivity to 254-nm UV radiation, and the addition of an nth (endonuclease III) mutation to nfo or nfo xth mutants did not significantly increase their sensitivity to any of the agents tested.

Alkylating Agents↗

PubMedDate not supplied

Effect of an ionic compared to a non-ionic X-ray contrast agent on platelets and coagulation during diagnostic cardiac catheterisation.

The aim of the present study was to evaluate the effects of ionic (ioxaglate) and non-ionic (iopromide) contrast media on haemostatic parameters ex vivo. In 40 patients undergoing coronary angiography, platelet function (platelet reactivity and serotonin concentration) and coagulation markers [thrombin-antithrombin III complexes, prothrombin fragments (F1+2) and the D-dimers] were measured. The use of an ionic X-ray contrast agent (XCA) (ioxaglate) in diagnostic cardiac catheterisation angiography is associated with lower thrombin generation and lower activation of the platelet system than when a non-ionic XCA is employed (iopromide). The results thus confirm the results of various in vitro studies and animal investigations.

Aged↗

PubMedDate not supplied

Isolation of Cryptococcus neoformans chromosome-specific probes using expressed sequence tags.

Clinical and environmental isolates of Cryptococcus neoformans exhibit a high degree of karyotypic variability. Analysis of the molecular basis of karyotypic differences requires a large set of chromosome-specific probes. We have determined the chromosomal distribution of a set of randomly selected C. neoformans cDNA clones and have explored the feasibility of identifying these clones through partial DNA sequencing. Forty-four randomly selected cDNA clones were labelled and hybridized to PFGE blots of C. neoformans. Expressed sequence tags were generated by sequencing the 5'-end of each clone. Thirty-five clones hybridized to single bands on PFGE blots. At least seven chromosomes were recognized by these probes. Homology searches identified potential homologs of several groups of proteins not previously studied in C. neoformans. PFGE hybridization and sequencing of random cDNA clones is an efficient method for identifying chromosomal-specific probes in fungi that lack extensive sets of genetic markers.

Chromosomes, Fungal↗