Flavin-containing monooxygenase: a major detoxifying enzyme for the pyrrolizidine alkaloid senecionine in guinea pig tissues

Evidence based on optimal pH, thermal stability, and enzyme inhibition data suggests that the NADPH-dependent microsomal N-oxidation of the pyrrolizidine alkaloid senecionine is carried out largely by flavin-containing monooxygenase in guinea pig liver, lung, and kidney. In contrast, the hepatic microsomal conversion of senecionine to the pyrrole metabolite (+/-)-6,7-dihydro-7-hydroxy-1-hydroxymethyl-5H-pyrrolizine (DHP) is catalyzed largely by cytochrome P450. However, the rate of senecionine N-oxide formation (detoxication) far exceeded the rate of DHP formation (activation) in guinea pig liver microsomes over a range of pHs (pH 6.8 to 9.8). In guinea pig lung and kidney microsomes, N-oxide was the major metabolite formed from senecionine with little or no production of DHP. The high rate of detoxication coupled with the low level of activation of senecionine in liver, lung, and kidney may help explain the apparent resistance of the guinea pig to intoxication by senecionine and other pyrrolizidine alkaloids.

Disproportionate alpha- and beta-mRNA sodium pump subunit content in canine vascular smooth muscle

Total RNA isolated from canine saphenous vein smooth muscle cells was examined for Na+ pump alpha- and beta-mRNA content by three increasingly sensitive methods: Northern analysis, RNase protection assay, and polymerase chain reaction. Northern analysis clearly showed the presence of beta-mRNA. An alpha 1 signal was not demonstrable using either Northern analysis with a 1.5-kb cDNA probe or RNase protection. However, an "alpha 1-like" transcript was detected using polymerase chain reaction with two sets of primers constructed to selected areas of the rat alpha 1-cDNA. These data suggest that beta-mRNA in canine blood vessels is in large excess of the alpha 1-mRNA. This discrepancy may be reflected in the relatively low number of Na+ pump sites in this tissue.

The effect of lipopolysaccharide on bovine mammary macrophage function

The effect of Escherichia coli lipopolysaccharide (LPS) on the expression of major histocompatibility complex (MHC) class II molecules by bovine mammary macrophages was examined. The ability of LPS-treated mammary macrophages to support antigen-specific T-cell proliferation, as a measure of their antigen presentation ability, was also evaluated. For this purpose, control and LPS-treated macrophages were pulsed with heat-killed Staphylococcus aureus and then cultured with S. aureus-sensitized T-cells. Our data show that LPS had no significant effect on the expression of MHC class II molecules on the surface of mammary macrophages. Furthermore, LPS-induced macrophages were no more active in supporting T-cell proliferation on a per cell basis than unstimulated macrophages. The lack of macrophage response to LPS with respect to expression of MHC class II molecules and the antigen presentation ability is another example of the hyporesponsive nature of macrophages isolated from the bovine mammary gland.

Secretion of interleukin-1 by bovine milk macrophages

The relative sensitivity of bovine blood monocytes and macrophages isolated from milk to lipopolysaccharide, with respect to interleukin 1 (IL-1) production, was evaluated. Addition of lipopolysaccharide (0 to 30 microgram/ml) to the culture medium resulted in increases in secreted and intracellular IL-1 activity for monocytes and milk macrophages, with maximal stimulation achieved at 30 micrograms of lipopolysaccharide/ml of medium. At this concentration of lipopolysaccharide, monocytes released 76% of the total IL-1, whereas milk macrophages released only 26% of the total IL-1 produced within the cell. Secretion of a small quantity of IL-1 was a common property of macrophages isolated from healthy and mastitic quarters. We concluded that limited secretion of IL-1 may render the milk macrophages less efficient in promoting lymphocyte activation.

Comparison of rainbow trout and mammalian cytochrome P450 enzymes: evidence for structural similarity between trout P450 LMC5 and human P450IIIA4

Studies were undertaken to determine the immunochemical relationship between constitutive trout cytochrome P450s and mammalian cytochrome P450IIIA enzymes. Polyclonal antibodies (IgG) generated against trout P450 LMC5 reacted strongly with P450IIIA1 in dexamethasone-induced rat liver microsomes and with P450IIIA4 in human liver microsomes in immunoblots. In contrast, rabbit anti-P450 LMC1 IgG did not recognize these proteins in rat and human liver microsomes. Reciprocal immunoblots using anti-rat P450IIIA1 showed that this antibody does not recognize trout P450 LMC1 or LMC5. However, anti-human P450IIIA4 IgG was found to cross react strongly with P450 LMC1 and LMC5. Progesterone 6 beta-hydroxylase activity of trout liver microsomes, a reaction catalyzed by P450 LMC5, was markedly inhibited by anti-P450IIIA4 and by gestodene, a mechanism-based inactivator of P450IIIA4. These results provide evidence for a close structural similarity between trout P450 LMC5 and human P450IIIA4.

The role of c-mos proto-oncoprotein in mammalian meiotic maturation

The developmentally regulated expression of c-mos oncogene has led to the speculation that this gene may be involved in gametogenesis and early development. To directly test this possibility, we have used an electric field mediated transfer method to introduce an antibody against the c-mos gene product into living immature mouse oocytes. Control oocytes exposed to the electric field without antibody, non-immune IgG, or c-mos antibody pre-absorbed with the mos peptide underwent normal germinal vesicle breakdown (GVBD) (90%) and formed a polar body by 8 h. Oocytes transferred with antibody against c-mos product underwent GVBD, and chromosome condensation as judged by Hoechst 33258 staining. However, antibody transferred oocytes did not form a polar body. Confocal fluorescence microscopy using antibodies against tubulin demonstrated that 90% of the oocytes that received antibody against c-mos did not assemble a meiotic spindle. In a few instances an abnormal spindle-like structure did form. Electron microscopy confirmed that the nuclear envelope disassembled and revealed many microtubules in a disorganized manner. Western blot analysis showed the presence of p39c-mos in mouse mature oocytes, spermatocytes and granulosa cells. These results suggest a role for c-mos in regulating the assembly and/or function of the spindle during meiotic division in murine.

IGF-I receptors in embryonic skeletal muscle of three strains of chickens selected for differences in growth capacity

IGF-I receptors in embryonic skeletal muscle from three strains of chickens have been characterized. Specific receptors for IGF-I were present in breast and thigh skeletal muscle of 13 d chicken embryos. Dissociation rate constants (Kd) for breast muscle of a slow growing layer strain (Leghorn), an intermediate growth strain (Synthetic Whiterock), and a fast growing broiler strain (Cornish) were 3.24, 3.04, and 2.68 nM, respectively. Kd for the thigh muscle of the slow, intermediate and fast growing strains were 3.30, 2.90 and 3.29 nM, respectively. Kd values were not significantly different between strains or between tissues (p greater than .05). Receptor concentration (Bmax) in breast muscle of slow, intermediate and fast growing strains were 1.22, 1.08 and 0.92 pM/mg protein, respectively. Receptor concentration in thigh muscle of the slow, intermediate and fast growing strains were 0.95, 0.76, and 0.79 pM/mg protein, respectively. Bmax values were significantly different (p less than .05) between breast muscle (1.08 +/- .05 pM/mg protein) and thigh muscle (.84 +/- .05 pM/mg protein). IGF-I receptor number for breast muscle although not statistically significant (p greater than .05), indicated a trend towards differences between the slow growing Leghorn strain and the faster growing Cornish strain. The results suggest that strains of birds with different growth capacity may have different densities of IGF-I receptors in breast skeletal muscle plasma membranes.

[Identification of 10 kinds of Zanthoxylum by pyrolysis GC]

In this paper, pyrolysis GC was applied to differentiate and fingerprint 10 kinds of Zanthoxylum on an OV-101 capillary column. Analytical conditions with this column, operating temperature, pyrolysis time and peak identifications are discussed.

[Adrenomyeloneuropathy in 4 brothers]

Four brothers with adrenomyeloneuropathy are reported. They have developed darkening of the skin the sign of adrenal insufficiency at age of 5-10. During 10 years after that time progressive spastic paraparesis has appeared gradually in all of them and has had aggrevative tendency abruptly in late. Three male cousins of the proband probably died of "juvenile type" of adrenoleucodystrophy.

Requirement of the c-mos protein kinase for murine meiotic maturation

Anti-sense mos oligonucleotides have been shown to block steps required for meiotic maturation of oocytes. In Xenopus oocytes, the block prevents germinal vesicle breakdown (GVBD), an early step in oocyte maturation. In mice the block induced by anti-sense mos occurs at a later step in oocyte maturation concerned with the first polar body emission. Here, we show that mouse oocyte maturation is blocked by introduction of anti-mos antibodies into immature functional oocytes. Antibodies that inhibit the mos kinase blocked GVBD. In contrast, anti-mos antibodies that permit the mos kinase to function do not block GVBD, but interfere with polar body formation. Antibodies pre-reacted with excess cognate peptide had no observable effects on maturation. These results indicate that the c-mos kinase function is required for activation of maturation-promoting factor (MPF) during meiosis. These findings are also consistent with our previous studies which show that the mos kinase directly phosphorylates cyclin B2, a component of MPF (Roy et al., 1990).

[The seroepidemiological observation on hepatitis delta virus infection]

To assess the relationship between hepatitis delta virus (HDV) infection and HBV and reveal the distribution of HDV infection and the feature of epidemic, we collected 271 cases of HBV infected people in Shijiazhuang area and tested anti-HD with EIA from April 1987 to October 1988. This study found the prevalence of HDV infection was as high as 12.92% (35/271), and male prevalence of anti-HD was 14.06% (27/192) and female 10.13% (8/79), but there was no significance difference (P greater than 0.05). This suggested that the area of Shijiazhuan was a spot where HDV infection was high. Among these people, the positive rate of anti-HD in chronic active hepatitis, chronic persistent hepatitis and cirrhosis was much higher than that in HBsAg carriers. These finding indicated that HDV infection (coinfection and superinfection) was important in pathogenesis of chronic hepatitis B and in exacerbating liver disease to cirrhosis. This study confirmed that there was no significant difference between HDV infection and age, sex and occupation among HBV infected people.

[Drug modulation of thromboxane A2/prostacyclin balance and lipid peroxidation in patients with coronary artery disease]

Sixty patients with coronary artery disease (CAD) were investigated in a randomized, placebo-controlled study. Therapeutic dose of diltiazem markedly inhibited the production of whole blood thromboxane A2(TXA2), but had no effect on the production of prostacyclin(PGI2). Both aspirin 20mg/d and diltiazem plus aspirin had marked inhibitive effects on both TXA2 and PGI2. The order of potency of the three regimens in decreasing TXA2/PGI2 ratio was diltiazem plus aspirin greater than diltiazem greater than aspirin. Diltiazem, aspirin and combination of both all decreased significantly serum lipid peroxides level, but had no effect on serum superoxide dismutase concentration. The results indicate that both therapeutic dose of diltiazem and low-dose of aspirin may modulate TXA2/PGI2 balance and inhibit lipid peroxidation in CAD and that the combination of both drugs may result in best therapeutic effect.

Expression and nucleotide sequence analysis of the Legionella pneumophila recA gene

The nucleotide sequence of the L pneumophila recA gene was determined. The coding region was 1044 nucleotides (348 codons), specifying a 37,934 Da protein. Preceding the recA gene was a tandem set of transcription regulatory sequences and putative LexA binding sites. When expressed in E. coli, the cloned recA gene yield two proteins with molecular weights of approximately 38,000 and 35,500 Da. The larger of these two proteins shared 70.4% and 74.6% identity with the E. coli and Pseudomonas aeruginosa RecA proteins, respectively. The 35,500 Da recA encoded protein was presumed to be the product of translation from Met26 which was preceded by an alternate ribosomal binding site.

Effects of N-acetylimidazole on oxytocin binding in bovine mammary tissue

The effects of N-acetylimidazole on specific binding of oxytocin to microsomal fractions of bovine mammary gland were studied. N-acetylimidazole suppressed oxytocin binding, with time and concentration dependence. Decreased oxytocin binding activity appeared to be due to decreased affinity of the hormone for its receptor. Acetylation of oxytocin, rather than of oxytocin receptors, seemed to be responsible for the decreased binding.

Genome-specific repetitive sequences in the genus Oryza

Repetitive DNA sequences are useful molecular markers for studying plant genome evolution and species divergence. In this paper, we report the isolation and characterization of four genome-type specific repetitive DNA sequences in the genus Oryza. Sequences specific to the AA, CC, EE or FF genome types are described. These genome-type specific repetitive sequences will be useful in classifying unknown species of wild or domestic rice, and in studying genome evolution at the molecular level. Using an AA genome-specific repetitive DNA sequence (pOs48) as a hybridization probe, considerable differences in its copy number were found among different varieties of Asian-cultivated rice (O. sativa) and other related species within the AA genome type. Thus, the relationship among some of the members of AA genome type can be deduced based on the degree of DNA sequence similarity of this repetitive sequence.

Establishment of human mesothelioma cell lines (MS-1, -2) and production of a monoclonal antibody (anti-MS) with diagnostic and therapeutic potential

We have established and characterized two mesothelioma cell lines, MS-1 and MS-2, in four attempts at long-term culture of these cells. Both MS-1 and MS-2 cells consistently express cytokeratin and vimentin, and both have long, slender microvilli. The cells that grew indefinitely (MS-1, MS-2) had a higher DNA index and a higher nucleus:cytoplasm ratio than did those cells that failed to grow (MS-3, MS-4). All mesothelioma cells, both in short- and in long-term culture, responded to phorbol ester induction by displaying morphological differentiation, such as an increase in the number of microvilli. The distribution of vimentin and cytokeratin in the cells, however, remained the same regardless of the growth pattern or the phorbol-ester treatment of the cells. We have used MS-1 cells to produce a monoclonal antibody (anti-MS) that reacts with mesothelioma cells, but rarely with reactive or normal mesothelial cells or with cells of normal tissues. The antibody does not induce the modulation of antigen, and it causes no direct or complement-mediated cytotoxicity of MS-1 or MS-2 cells. If a toxin or an isotope conjugate of the antibody is used, it may be valuable in the near future to test it for use in immunoimaging or immunotherapy.