Effects of unsaturated fatty acids on the peroxisomal enzyme activities of Tetrahymena pyriformis

The effects of unsaturated fatty acids on the activities of peroxisomal enzymes of Tetrahymena pyriformis were investigated. When saturated fatty acids and the corresponding unsaturated fatty acids (C18) were added to the culture medium at 0.05%, the activities of peroxisomal enzymes [fatty acyl-CoA oxidase (FAO), carnitine acetyltransferase (CAT), isocitrate lyase (ICL), and malate synthase (MS)] were significantly increased. The order of effectiveness was linoleic acid greater than oleic acid greater than stearic acid. However, alpha-linolenic acid and gamma-linolenic acid at the same concentration were lethal to the cells. The inhibitory effect on growth disappeared upon addition of an antioxidant, alpha-tocopherol. Lipid peroxides derived from unsaturated fatty acids induced marked cell lysis. In the presence of a low concentration (0.005%) of linolenic acid the production of lipid peroxide was lower and no inhibitory effect on the growth was observed, while the activities of peroxisomal enzymes participating in lipid metabolism and that of catalase were significantly increased. These results indicate that the peroxisomal enzyme systems related to the beta-oxidations of fatty acids and the glyoxylate cycle are regulated by unsaturated long-chain fatty acids, including linolenic acid, at low concentrations, as well as by saturated fatty acid in the medium.

Impaired B cell proliferation by Staphylococcus aureus Cowan 1 in patients with systemic lupus erythematosus

We examined the proliferative response to Staphylococcus aureus Cowan 1 (SAC) by enriched peripheral blood B cells from patients with systemic lupus erythematosus (SLE). Responses of B cells from patients with active and inactive SLE were significantly lower than those of B cells from normal individuals. Hyporesponsiveness to SAC was not observed in healthy family members of SLE patients. This hyporesponsiveness did not correlate with prednisolone therapy and could not be attributed to serum factors; it did correlate with the presence of suppressor monocytes. However, we could not exclude the possibility of enhanced sensitivity of SLE B lymphocytes to suppressive signals delivered by the monocytes.

Possible mechanism of action of diazepam as an adenosine potentiator

Diazepam (10(-5)-3 X 10(-4) M) selectively enhanced the negative inotropic responses of guinea-pig atria and the relaxation of guinea-pig taenia coli caused by adenosine and ATP. In the atria, the effect of 2-chloroadenosine, a stable analog of adenosine, was not affected by diazepam. Segments of guinea-pig atria or taenia coli took up 3H-activity during incubation with [3H]adenosine but did not take up 32P-activity from [32P]ATP. Diazepam at concentrations sufficient to enhance the in vitro responses reduced by half the uptake of 3H-activity into the preparations. Adenosine (10(-6) M) and ATP (10(-6) M) were degraded to inactive inosine during incubation with atrial segments and their degradation was inhibited by diazepam. In contrast, in rat atria, diazepam did not enhance the negative inotropic effects of adenosine and ATP, and did not prevent the uptake of adenosine. These results suggest that in guinea-pig atria and taenia coli, diazepam like dipyridamole, acts as an adenosine potentiator by preventing the uptake and degradation of adenosine.

The regulation of peroxisomal enzyme systems of Tetrahymena pyriformis by fatty acid composition, glucose and oxygen in the medium

The effect of the chain length of fatty acids on peroxisomal enzyme activities of Tetrahymena pyriformis was investigated. The growth of cells and the activities of peroxisomal enzymes were inhibited markedly by the addition of medium-chain fatty acids (C6-C12) to the culture medium, whereas the addition of longer-chain fatty acids (C14-C18) resulted in a slight increase of growth and in the marked stimulation of enzyme activities concerned with fatty acid beta-oxidation and the glyoxylate cycle in peroxisomes. Peroxisomal beta-oxidation (fatty acyl-CoA oxidase) was more potent towards longer-chain fatty acids than the mitochondrial activity (fatty acyl-CoA dehydrogenase). The induction of the peroxisomal beta-oxidation system by palmitate was repressed both by the addition of glucose and the aeration of the culture medium, whereas that of the peroxisomal glyoxylate cycle was repressed only by the addition of glucose to the medium. These results indicate that peroxisomal enzyme systems related to the beta-oxidation of fatty acids and the glyoxylate cycle are regulated by the compositions of fatty acids, glucose, and oxygen in the medium.

The role of interferon-gamma in induction of differentiation of human myeloid leukemia cell lines, ML-1 and HL-60

Highly purified natural interferon-gamma (IFN-gamma) induced differentiation having characteristics that are associated with the human promyelocytic leukemia cell line, HL-60. Monoclonal antibody to INF-gamma neutralized its activity. However, the natural IFN-gamma had almost no inducing activity in ML-1, a human myeloblastic leukemia cell line. Similar results were obtained using recombinant IFN-gamma. Mitogen stimulated human leukocyte conditioned medium (LCM) induced differentiation of both ML-1 and HL-60 cells. After treatment of LCM with monoclonal antibody to IFN-gamma, LCM activity was reduced more than 50% in ML-1 cells, and 80% in HL-60 cells. Even if IFN-gamma was eliminated from LCM by affinity chromatography, the LCM induced differentiation of ML-1 and HL-60 cells, but IFN-gamma markedly enhanced the ML-1 cell differentiation induced by IFN-gamma free LCM. The results suggest that leukocytes produce differentiation inducing factor(s) other than IFN-gamma, and that IFN-gamma is both an inducer and an enhancer of induction of human myelogenous leukemia cells.

Papaverine enhances the effect of adenosine in guinea-pig atria

Papaverine, while enhancing the force of contraction of guinea-pig atria, remarkably and dose-dependently enhanced the negative inotropic response of the atria to adenosine. It also enhanced the actions of ATP and other adenine nucleotides, but not those of 2-chloroadenosine and ACh. At similar concentrations, papaverine inhibited the uptake of adenosine by the atrial tissue during incubation with adenosine. Adenosine in the medium was degraded to inactive inosine during incubation with the atrial tissue, and papaverine reduced its degradation. The enhancing effect of papaverine on the action of adenosine on guinea-pig atria was like those of dipyridamole, 6-(2-hydroxy-5-nitrobenzyl)thioguanosine and cinepazide. The effect seemed to be due mainly to inhibition of adenosine uptake into the tissue. Inhibition of adenosine degradation may also have contributed to the action of papaverine, but this action was probably much less important than inhibition of adenosine uptake.

Tripeptides acting on opioid receptors in rat colon

The tripeptides SD-34 and SD-25 induced atropine-, guanethidine-, antihistaminics-resistant but naloxone-sensitive contractions of isolated rat distal colon. They appeared to act on an opioid receptor, probably of the mu subtype, distinct from those for methionine enkephalin and morphine, because the pA2 values of naloxone for the peptides were similar to those for mu-agonists but different from those for methionine enkephalin and morphine, and because the peptides caused contractions of colon that had been desensitized to morphine. Mr 2266, a supposed kappa-antagonist, inhibited the actions of the peptides, ethylketocyclazocine and dynorphin at concentrations much lower than those inhibiting the actions of methionine enkephalin and morphine. Thus these peptides seem to act on the mu- and/or kappa-receptors. The actions of the tripeptides were inhibited by methysergide and methylergometrine, but not by the 5-HT2 antagonist ketanserin, and were not affected by 5-HT or substance P autodesensitization . Thus their actions do not seem to involve 5-HT, histamine, ACh or substance P. It seems likely that the tripeptides, through opioid receptors, directly activate the muscle, or remove some inhibitory modulation of myogenic activity, thus causing contractions.

Immunopathology of vitiligo vulgaris, Sutton's leukoderma and melanoma-associated vitiligo in relation to steroid effects. I. Circulating antibodies for cultured melanoma cells

Sera of patients with various types of vitiligo have been found to contain circulating antibodies for the cytoplasmic components of human melanoma cell lines. This incidence is high, especially in generalized vitiligo vulgaris with or without Sutton's phenomenon. There is good correlation between the antibodies and positive microsome test, thyroid test, DNA test, as well as the effect of steroid ointment.

Immunopathology of vitiligo vulgaris, Sutton's leukoderma and melanoma-associated vitiligo in relation to steroid effects. II. The IgG and C3 deposits in the skin

Microsome, thyroid and DNA tests on patients with generalized vitiligo vulgaris, with or without Sutton's leukoderma, show a high positive rate without thyroid diseases. A small, but not negligible, amount of IgG and C3 deposits in the basement-membrane zone and keratinocytes, has been frequently seen in these diseases by immunohistology and immuno-electron microscopy. This evidence strongly suggests an autoimmune character for these diseases.

Gastrointestinal and hepatic first-pass metabolism of aspirin in rats

The first-pass effect of aspirin was measured in male Wistar rats by comparing the plasma concentration after intravenous, oral or intraportal administration (10 mg kg-1) of the drug. Approximately 88 and 86% of the dose was excreted mostly as salicylic acid and its conjugated forms, glucuronide and sulphate, in urine within 48 h of i.v. or oral administration, respectively. This suggests that the gastrointestinal absorption of aspirin was essentially complete in rats. On the average, the area under the plasma concentration-time curve for unchanged aspirin following oral dosing (AUCo) was 0.35 of that obtained following i.v. administration (AUCi.v.) and 0.53 of that following intraportal administration (AUCp). Therefore, orally administered aspirin is subject to first-pass metabolism both in the gut and in the liver of rats. The gastrointestinal first-pass effect is estimated to be relatively more important than the hepatic effect.

Histamine release from rat mast cells induced by an extract from the sea urchin Toxopneustes pileolus

The extract caused a dose-dependent release of histamine from rat peritoneal mast cells which was slower in onset than that of compound 48/80. It is also suggested that the extract-induced histamine release is dependent on aerobic glycolysis.

Interaction of cinepazide with adenosine on guinea-pig atria

The negative inotropic effects of adenosine and adenine nucleotides, such as ATP and cAMP, on guinea-pig atria were selectively and dose-dependently augmented by cinepazide in concentrations insufficient to produce any effect alone (3 X 10(-5) M-3 X 10(-4)M). Adenosine (10(-5) M, 10 microCi) was degraded to inosine and hypoxanthine during incubation with atrial tissue. Cinepazide (3 X 10(-4) M) retarded the degradation of adenosine, and the formation of inosine and hypoxanthine. Incubation of the atrial tissue with adenosine (8.1 X 10(-9) M, 0.1 microCi) resulted in accumulation of 3H-activity. Cinepazide (3 X 10(-5) M-3 X 10(-4) M) inhibited this accumulation. These results suggest that cinepazide potentiates the negative inotropic effect of adenosine on guinea-pig atria by preventing both its degradation by deaminase and its accumulation by atrial tissue.