Requirement for a macromolecular factor for sodium azide activation of guanulate cyclase.

Sodium azide, a highly nucleophilic agent and a potent metabolic inhibitor, markedly increased guanylate cyclase activity from supernatant fractions of rat liver homogenates. The effect of sodium azide was not observed with partially purified guanulate cyclase from liver or crude soluble guanylate cyclase from cerebral cortex. However, the effect of sodium azide could be restored by the readdition of a fraction isolated from rat liver homogenates. The macromolecular factor required for the sodium azide effect was separated from soluble guanylate cyclase of rat liver with DEAE-cellulose column chromatography, and some of its properties were examined. The factor was nondialyzable and heat labile.     

Mechanism and stereospecificity of alpha-hydroxylation of lignoceric acid in rat brain.

Cerebronic acid (2-hydroxytetracosanoic acid) is the major fatty acid component of cerebrosides and sulfatides in mammalian brain. Our previous communication demonstrated the synthesis of cerebronic acid from lignoceric acid (tetracosanoic acid) by a rat brain preparation in the presence of molecular oxygen and a reduced pyridine nucleotide (Hoshi, M., and Kishimoto, Y. (1973) J. Biol. Chem., 248, 4123–4130). The present'studies on the conversion of (RS)-[2-³H]-, (RS)-[3-³H]-, (R)-[2-³H]-, and (S)-[2-³H]lignoceric acids to cerebronic acid by rat brain preparations establish that the pro-R hydrogen at the α-carbon of lignoceric acid is replaced by a hydroxyl group with overall retention of configuration.     

Human chromosome 19 carries a poliovirus receptor gene

The chromosome complements of human/mouse hybrid cell lines of mouse 3T3-4E and RAG parentage have been analyzed using chromosome banding methods. Three lines that were susceptible to lytic infection with poliovirus contained eleven to seventeen human chromosomes, including chromosome 19. Polio-resistant sublines of these contained no chromosome 19 and showed no other consistent change in the complement of human chromosomes. Human chromosome 19 therefore is essential for polio-sensitivity. Since polio sensitivity was correlated with receptor activity in these lines, we conclude that chromosome 19 carries the structural gene for the poliovirus receptor. Sensitivity to echo-7 and Rhino-1A viruses could not be related to the presence of a specific human chromosome.     

Adenosine 3′,5′-monophosphate and guanosine 3′,5′-monophosphate: concentrations in Morris hepatomas of different growth rates

Cyclic AMP and cyclic GMP levels were examined in Morris hepatoma explants in vivo. All eight tumor lines examined had significantly elevated cyclic AMP and cyclic GMP levels when compared to normal liver from tumor-bearing rats. No apparent correlation was observed between the rates of tumor growth and cyclic nucleotide levels; however, two tumor lines (3924A and 7288ctc) had very high levels of cyclic GMP.     

Purified guanylate cyclase: characterization, iodination and preparation of monoclonal antibodies

Guanylate cyclase was purified from the soluble fraction of rat lung using a modification of procedures published previously. The purified enzyme exhibited specific activities, at pH 7.6, of 219-438 nmoles/mg protein/min and 34-60 nmoles/mg protein/min with Mn2+ and Mg2+ as cation cofactors, respectively. The specific activity changed as a function of the protein concentration due to a change in Vmax with no alteration of the Km for GTP. The enzyme migrated as a single band coincident wih guanylate cyclase activity on nondenaturing polyacrylamide and isoelectric focusing gels (isoelectric point = 5.9). Purified guanylate cyclase had an apparent molecular weight of 150,000 daltons as determined by gel filtration chromatography and polyacrylamide gel electrophoresis. Electrophoresis in the presence of sodium dodecyl sulfate revealed a single subunit of 72,000 daltons, suggesting that the enzyme is a dimer of an identical subunit. The purified enzyme could be activated by nitric oxide, indicating that this compound interacts directly with the enzyme.     

Dual-parameter flow cytometric analysis coupling the measurements of forward-angle light scatter and DNA content of archival ovarian carcinomas of low malignant potential

Paraffin-embedded archival specimens from 45 cases of ovarian carcinoma of low malignant potential (OCLMP) were analyzed by flow cytometry (FCM) using propidium iodide (PI) staining. Since single-parameter FCM analysis is often deficient in the resolution of subtle near-diploid DNA-aneuploid populations, forward-angle light scatter (FALS) was measured as a second parameter. DNA aneuploidy was identified in 15 cases (33%). In 7 of those 15 cases, aneuploidy was resolved with single-parameter FCM; in the remaining 8 cases, DNA aneuploidy was resolved only following dual-parameter analysis coupling DNA content and FALS. In all 15 cases, a single near-diploid aneuploid population was observed (mean DNA index = 1.2); there were no tetraploid aneuploid cases. The proliferative activity for all 45 cases studied ranged from 1.0% to 8.9%, with a mean of 3.5%. No difference in mean proliferative activity was observed between the aneuploid and diploid tumors (P greater than .05). To exclude the possibility that PI staining artifacts caused the observed aneuploidy, five of the eight cases shown to be aneuploid by dual-parameter analysis were further studied using an alternate DNA-binding dye, DAPI, yielding similar results. To exclude the possibility that contaminating stromal and/or inflammatory cells caused the observed aneuploidy, samples from a subset of the dual-parameter cases were sorted, revealing the aneuploid populations to be composed primarily of tumor nuclei.(ABSTRACT TRUNCATED AT 250 WORDS)     

Bacterial SCP from methanol in Kuwait: Product revovery and composition

The rationale behind KISR's involvement in SCP is explained and emphasis towards the use of aerobic thermophilic/thermotolerant methanol-utilizing bacterial cultures is stressed. An attempt is made to correlate different pilot plant harvesting procedures for biomass recovery with product quality. The latter is expressed as crude and true protein content, moisture and ash content, mineral composition of the ash, and amino acids profiles. The most suitable harvesting procedures were found to be those using a mild heat-acid or acid-heat treatment. Both of these procedures gave high recovery efficiencies and suitable product nutrition.     

Binding and penetration ofRhizobium japonicum to cultured soybean cells

A cultured soybean cell line, SB-1 was used to evaluate the initial interaction between the soybean cells andRhizobium japonicum. Co-culturing ofR. japonicum with SB-1 cells in suspension resulted in strain-specific polar attachment. This attachment can be inhibited by galactose and antibodies raised against seed soybean agglutinin (SBA). A lectin was purified from SB-1 cells which shares properties with SBA in terms of immunological reactivity, sugar binding activity, polypeptide molecular weight and peptide maps. When the SB-1 cells were co-cultured withR. japonicum for three weeks in solid agar medium, histological staining revealed bacterial penetration into certain SB-1 cells. Furthermore, there were focal regions of cells with prominent nuclei representing actively proliferating regions. These observations are analogous to that ofin vivo nodule initiation in soybean roots.     

Response of primary human mammary tumor cell cultures to a monoclonal antibody-recombinant ricin A chain immunotoxin

Summary Malignant epithelial tumor cells were isolated and cultured from ten human mammary specimens of cancerous origin. The 260F9 monoclonal antibody (MAB) bound to frozen sections of all of the human breast tumors tested and to primary cultured cells from the tumors. Cultured cells from all ten breast tumors were sensitive to the clonal inhibitory effects of immunotoxin 260F9 MAB-recombinant ricin A chain. At an immunotoxin concentration of 200 ng/ml (about 1 nM), inhibition of colony formation was >99% for all ten tumors.