Ultrastructure of the acidophilic aerobic photosynthetic bacterium Acidiphilium rubrum

The ultrastructure of cells of Acidiphilium rubrum, which is an acidophilic aerobic photosynthetic bacterium containing zinc-complexed bacteriochlorophyll a, was studied by electron microscopy with the rapid substitution technique. Thin-section electron microscopy indicated that any type of internal photosynthetic membranes was not present in this organism despite a relatively high content of the photopigment. The majority of cells had poly-beta-hydroxybutyrate granules and electron-dense spherical bodies identified as being polyphosphate granules. When the organism was grown chemotrophically with 0.1% FeSO(4), it produced another group of electron-dense granules that were associated with the inner part of the cytoplasmic membrane. An energy-dispersive X-ray analysis showed that these membrane-bound, electron-dense granules contained iron.

High-frequency occurrence of chromosome translocation in a mutant strain of Candida albicans by a suppressor mutation of ploidy shift

Significant occurrence of high-ploidy cells is commonly observed among many Candida albicans strains. We isolated two isogenic strains, STN21 and STN22, each from a half sector of a colony obtained after mild UV-irradiation of a Arg(-) derivative of CBS5736. The two strains were different from each other in ploidy states and chromosome organization. Although cells of STN22 were homogeneous in size and had a single nucleus, high-ploidy cells, with either a single large nucleus or several nuclei, were present together with apparently normal cells with a single nucleus in the cell population of STN21. Flow cytometry showed that STN22 was a stable diploid; however, STN21 seemed to be the mixture of different ploidy states, including diploid and tetraploid. The phenotype of STN21 containing high-ploidy cells is referred to here as the Sps(-) phenotype (suppressor of ploidy shift). STN22 showed a typical electrophoretic karyotype similar to strain 1006 in C. albicans. However, an extra chromosomal band appeared in some clones of STN21 at high frequency. By assignment of several DNA probes, this extra chromosome was shown to be a translocation of the 7F-7G portion of chromosome 7 with the 470 kb DNA segment containing H SfiI fragment from chromosome 4. Thus, this extra chromosome is a hybrid of 4H and 7F-7G. Since the isogenic Sps(+) strain STN22 exhibited no extra chromosome bands, a correlation is suggested between the Sps(-) phenotype and the occurrence of chromosome translocations.

Circulating p53 antibody in patients with colorectal cancer: relation to clinicopathologic features and survival

The presence of serum anti-p53 antibody has been reported to be associated with survival of patients with breast cancer, ovarian cancer, and hepatocellular carcinoma. To clarify prognostic significance of p53 antibody in colorectal cancer, serum p53 antibody was measured in patients with colorectal cancer. The 89 patients included 71 with colorectal cancer and 18 with colon polyp. An enzyme-linked immunosorbent assay was used to detect p53 antibodies in serum. Clinicopathological parameters such as age, sex, degree of differentiation of cancer, location of tumor, liver metastasis, stage classification, Dukes classification, CEA, CA19-9, and immunostaining of p53 and anti-p53 antibody were evaluated as prognostic factors of colorectal cancer. p53 antibody was positive in 18 of 71 (25%) with colorectal cancer, whereas it was positive in only 1 of 18 (6%) with colon polyp. The patients with p53 antibody had higher CEA and CA19-9 levels, higher positive rates of p53 protein expression in cancer cells, and higher liver metastasis rates. The p53 antibody positivity at stage classification I-IIIb/ Dukes classification A-C was significantly lower than that at stage classification IV/Dukes classification D. Overall survival in colorectal cancer patients with p53 antibody was significantly shorter than in those without p53 antibody. A Cox regression analysis showed that liver metastasis, stage classification, Dukes classification, CA19-9, and p53 antibody were significant prognostic factors in colorectal cancer. Serum anti-p53 antibody could serve as one of the prognostic factors in patients with colorectal cancer.

Circulating p53 antibody in patients with colorectal cancer: relation to clinicopathologic features and survival

The presence of serum anti-p53 antibody has been reported to be associated with survival of patients with breast cancer, ovarian cancer, and hepatocellular carcinoma. To clarify prognostic significance of p53 antibody in colorectal cancer, serum p53 antibody was measured in patients with colorectal cancer. The 89 patients included 71 with colorectal cancer and 18 with colon polyp. An enzyme-linked immunosorbent assay was used to detect p53 antibodies in serum. Clinicopathological parameters such as age, sex, degree of differentiation of cancer, location of tumor, liver metastasis, stage classification, Dukes classification, CEA, CA19-9, and immunostaining of p53 and anti-p53 antibody were evaluated as prognostic factors of colorectal cancer. p53 antibody was positive in 18 of 71 (25%) with colorectal cancer, whereas it was positive in only 1 of 18 (6%) with colon polyp. The patients with p53 antibody had higher CEA and CA19-9 levels, higher positive rates of p53 protein expression in cancer cells, and higher liver metastasis rates. The p53 antibody positivity at stage classification I-IIIb/ Dukes classification A-C was significantly lower than that at stage classification IV/Dukes classification D. Overall survival in colorectal cancer patients with p53 antibody was significantly shorter than in those without p53 antibody. A Cox regression analysis showed that liver metastasis, stage classification, Dukes classification, CA19-9, and p53 antibody were significant prognostic factors in colorectal cancer. Serum anti-p53 antibody could serve as one of the prognostic factors in patients with colorectal cancer.

Minimum chemical requirements for adhesin activity of the acid-stable part of Candida albicans cell wall phosphomannoprotein complex

This study was conducted to define adhesive characteristics of the acid-stable moiety of the Candida albicans phosphomannoprotein complex (PMPC) on adherence of this fungus to marginal zone macrophages of the mouse spleen. Complete digestion of the acid-stable moiety (Fr.IIS) of the C. albicans PMPC with an alpha-mannosidase or hydrolysis with 0.6 N sulfuric acid destroyed adhesin activity, as determined by the inability of the soluble digests to inhibit yeast cell adherence to the splenic marginal zone. Fr.IIS adhesin activity was decreased following digestion with an alpha-1,2-specific mannosidase. Oligomannosyls consisting of one to six mannose units, which were isolated from the acid-stable part of the PMPC, did not inhibit yeast cell binding and thus do not function alone as adhesin sites in the PMPC. To gain more insight into the minimum requirements for adhesin activity, PMPCs were isolated from a Saccharomyces cerevisiae wild-type strain and from mutant strains mnn1, mnn2, and mnn4; the PMPCs were designated scwt/Fr.II, scmn1/Fr.II, scmn2/Fr.II, and scmn4/Fr.II, respectively. S. cerevisiae scmn2/Fr.II lacks oligomannosyl side chain branches from the outer core mannan, and scmn2/Fr.II was the only PMPC without adhesin activity. S. cerevisiae scwt/Fr.II, scmn1/Fr.II, and scmn4/Fr.II showed adhesin activities less than that of C. albicans Fr.II. These three S. cerevisiae PMPCs are generally similar to Fr. IIS, except that the S. cerevisiae structure has fewer and shorter side chains. Immunofluorescence microscopy show that the acid-stable part of the PMPC is displayed homogeneously on the C. albicans yeast cell surface, which would be expected for a surface adhesin. Our results indicate that both the mannan core and the oligomannosyl side chains are responsible for the adhesin activity of the acid-stable part of the PMPC.

Cloning and characterization of CAD1/AAF1, a gene from Candida albicans that induces adherence to endothelial cells after expression in Saccharomyces cerevisiae

Adherence to the endothelial cell lining of the vasculature is probably a critical step in the egress of Candida albicans from the intravascular compartment. To identify potential adhesins that mediate the attachment of this organism to endothelial cells, a genomic library from C. albicans was used to transform a nonadherent strain of Saccharomyces cerevisiae. The population of transformed yeasts was enriched for highly adherent clones by repeated passages over endothelial cells. One clone which exhibited a fivefold increase in endothelial cell adherence, compared with S. cerevisiae transformed with vector alone, was identified. This organism also flocculated. The candidal DNA fragment within this adherent/flocculent organism was found to contain a single 1.8-kb open reading frame, which was designated CAD1. It was found to be identical to AAF1. The predicted protein encoded by CAD1/AAF1 contained features suggestive of a regulatory factor. Consistent with this finding, immunoelectron microscopy revealed that CAD1/AAF1 localized to the cytoplasm and nucleus but not the cell wall or plasma membrane of the transformed yeasts. Because yeasts transformed with CAD1/AAF1 both flocculated and exhibited increased endothelial cell adherence, the relationship between adherence and flocculation was examined. S. cerevisiae expressing either of two flocculation phenotypes, Flo1 or NewFlo, adhered to endothelial cells as avidly as did yeasts expressing CAD1/AAF1. Inhibition studies revealed that the flocculation phenotype induced by CAD1/AAF1 was similar to Flo1. Thus, CAD1/AAF1 probably encodes a regulatory protein that stimulates endothelial cell adherence in S. cerevisiae by inducing a flocculation phenotype. Whether CAD1/AAF1 contributes to the adherence of C. albicans to endothelial cells remains to be determined.

A crossreactivity at the immunoglobulin E level of the cell wall mannoproteins of Candida albicans with other pathogenic Candida and airborne yeast species

BACKGROUND

Candida albicans crossreacts with Saccharomyces cerevisiae or Pityrosporum ovale at the IgE level. However, the extent of crossreactivity of C. albicans with other yeast species is not known.

OBJECTIVE

The crossreactivity at the immunoglobulin E (IgE) level of Candida albicans with other pathogenic Candida species and to the airborne yeast species Cryptococcus and Rhodotorula was studied by immunoblot analysis.

METHODS

Crude antigens, designated as heat extract, were prepared from 13 different yeast species and a dot blot test was performed to detect IgE antibodies against each of the heat extracts in 349 patients with allergies who were positive for IgE antibodies against C. albicans in a CAP system.

RESULTS

In the dot blot test, most of the sera reacted with the heat extracts of not only C. albicans but also those prepared from the other yeast species. The sera of 41 of the 349 patients (11.7%) reacted with the heat extracts of all 13 yeast species. The extent of the binding of IgE antibodies to multiple yeast species correlated with both the fluorescence intensities measured in the CAP system and the intensities of dots generated by the heat extract of C. albicans in the dot blot test. In an inhibition dot blot test, mannoproteins, but not proteins, of C. albicans strongly inhibited the subsequent binding of IgE antibodies to all yeast species.

CONCLUSION

Our data suggest that the C. albicans mannoproteins are responsible for the crossreactivity among these yeast species at the IgE level.

Biochemical characterization of Candida albicans epitopes that can elicit protective and nonprotective antibodies

We previously reported that the immunoglobulin M (IgM) monoclonal antibody (MAb) B6.1 protects mice against disseminated candidiasis, whereas the IgM MAb B6 does not. Both MAbs are specific for an adhesin fraction isolated from the cell surface of Candida albicans, but their epitope specificities differ. In the present study, we examined the surface locations of both epitopes and obtained structural information regarding the B6.1 epitope. Immunofluorescence confocal microscopic analysis of C. albicans yeast forms showed that epitope B6.1 is displayed rather homogeneously over the entire cell surface, whereas epitope B6 appears to have a patchy distribution. Both antibodies were essentially nonreactive with the surfaces of mycelial forms of the fungus, indicating that neither epitope is expressed on the surfaces of these forms. For isolation of the B6.1 epitope, the adhesin fraction consisting of cell surface phosphomannan was subjected to mildly acidic (10 mM HCl) hydrolysis and was fractionated into acid-labile and acid-stable portions by size exclusion chromatography. Antibody blocking experiments showed that the B6.1 epitope is an acid-labile moiety of the phosphomannan and that the B6 epitope is located in the acid-stable fraction. The B6 epitope appeared to be mannan because it was stable to heat (boiling) and protease treatments but was destroyed by alpha-mannosidase digestion. The B6.1 epitope eluted from the size exclusion column in two fractions. Mass spectroscopic analyses showed that one fraction contained material with the size of a mannotriose and that the other was a mixture of mannotriose- and mannotetraose-size substances. Dose response inhibition tests of the fractions indicated that the B6.1 epitope is associated with the mannotriose. Nuclear magnetic resonance (NMR) spectroscopic analysis of the epitope yielded data consistent with a beta-(1-->2)-linked mannotriose. The fine structure of the B6 epitope is under investigation. Information derived from these investigations will be useful both in understanding protective versus nonprotective antibody responses to C. albicans and in improving anti-Candida vaccine formulations.

Endothelin-1 inhibits nitric oxide synthesis in vascular smooth muscle cells

We investigated the effects of endothelin-1 on nitric oxide synthesis in vascular smooth muscle cells. We measured the production of nitrite, a stable metabolite of nitric oxide, and the expression of inducible nitric oxide synthase mRNA and protein in cultured rat vascular smooth muscle cells. Incubation of the cultures with interleukin-1 beta (10 ng/mL) for 24 hours caused a significant increase in nitrite production. Endothelin-1 significantly decreased the interleukin-1 beta-induced nitrite production by vascular smooth muscle cells in a dose-dependent manner (10(-11) to 10(-8) mol/L). Incubation with interleukin-1 beta for 24 hours induced expression of inducible nitric oxide synthase mRNA and protein in vascular smooth muscle cells, whereas endothelin-1 showed a suppressive effect on their expressions. Addition of the endothelin type A receptor antagonist BQ-485, but not the endothelin type B receptor antagonist BQ-788, dose-dependently inhibited the effect of endothelin-1. After protein kinase C activity was functionally depleted by treatment of cells with phorbol 12-myristate 13-acetate for 24 hours, the effect of endothelin-1 was abolished. These results indicate that endothelin-1 acts on endothelin type A receptors and inhibits nitric oxide synthesis in interleukin-1 beta-stimulated vascular smooth muscle cells at least partially through a protein kinase C-dependent pathway.

Adrenomedullin augments inducible nitric oxide synthase expression in cytokine-stimulated cardiac myocytes

BACKGROUND

Plasma levels of adrenomedullin are increased in patients with congestive heart failure, but there has been no report concerning the effects of adrenomedullin on the heart. We investigated the effects of adrenomedullin on NO synthase activity in cardiac myocytes.

METHODS AND RESULTS

We measured the production of nitrite, a stable metabolite of NO, in cultured neonatal rat cardiac myocytes with the Griess reagent. Inducible NO synthase mRNA and protein expression were assayed by Northern and Western blotting, respectively. Incubation of the cultures with interleukin-1 beta (10 ng/mL) for 24 hours caused a significant increase in nitrite accumulation. Adrenomedullin significantly augmented nitrite production by interleukin-1 beta-stimulated but not by unstimulated cardiac myocytes in a dose-dependent manner (10(-10) to 10(-6) mol/L). The adrenomedullin-induced nitrite production by interleukin-1 beta-stimulated cells was accompanied by increased inducible NO synthase mRNA and protein expression. In the presence of dibutyryl cAMP, the interleukin-1 beta-induced nitrite accumulation was increased further, but the stimulatory effect of adrenomedullin on nitrite production was abolished. Adrenomedullin dose-dependently increased intracellular cAMP levels in cardiac myocytes. Addition of the calcitonin gene-related peptide (CGRP) receptor antagonist CGRP[8-37] to the culture dose-dependently inhibited both cAMP and NO generation stimulated by adrenomedullin.

CONCLUSIONS

These results indicate that adrenomedullin acts on cardiac myocytes and augments NO synthesis in these cells under cytokine-stimulated conditions, at least partially through a cAMP-dependent pathway.

Highly hydrogenated dietary soybean oil modifies the responses to polychlorinated biphenyls in rats

The effects of dietary highly hydrogenated soybean oil (HSO) upon the changes caused by dietary polychlorinated biphenyls (PCBs) were examined in rats. Six groups of rats were fed the following diets for 30 d: a 20% soybean oil-containing diet (control diet), a diet in which a half of soybean oil was substituted with HSO (HSO-A diet), a diet in which cellulose powder was replaced with HSO (HSO-B diet) and these diets supplemented with 100 ppm PCBs (control + PCBs, HSO-A + PCBs and HSO-B + PCBs diets). Hepatic concentration of PCBs and relative liver weight were markedly decreased in rats fed with the HSO-A + PCBs diet compared with those fed with the other diets containing PCBs. Liver lipids and liver cholesterol were considerably decreased with a reciprocal increase in fecal sterol excretion by rats fed the HSO-A + PCBs and the HSO-B + PCBs diets compared with those fed with the control + PCBs diet. The fatty acid composition in hepatic phospholipids showed an independent increase of the saturated fatty acid content induced by dietary HSO and PCBs. Dietary PCBs also caused decreases in the amounts of monounsaturated and n-3 polyunsaturated fatty acids. These results suggest that dietary HSO prevents accumulation of PCBs in the liver and promotes the excretion of lipids stimulated by PCBs, accompanied by a change in fatty acid metabolism.

Evidence for the presence of immunoglobulin E antibodies specific to the cell wall phosphomannoproteins of Candida albicans in patients with allergies

To determine the major antigenic component of Candida albicans against immunoglobulin E (IgE) antibodies in the sera of patients with allergies who were positive for IgE antibodies to C. albicans crude antigen in a CAP system, phosphomannoproteins (CAMP/A or CAMP/B for serotype A or B strain, respectively) and their acid-stable portions (CAMP-S/A or CAMP-S/B) were isolated from beta-mercaptoethanol (2-ME) extracts of C. albicans cells of serotypes A and B, and IgE antibodies against these components were compared with those against protein complex and enolase (CAE) fractions isolated from C. albicans cells. The dot blot test, which was used to detect IgE antibodies to the C. albicans antigens, showed that IgE antibodies to the 2-ME extract and phosphomannoprotein fractions were present in the sera of 98.0% (2-ME extract), 96.8% (CAMP/A), 93.2% (CAMP-S/A), 97.2% (CAMP/B), and 81.5% (CAMP-S/B) of the patients, whereas IgE antibodies to the protein complex and CAE fractions were found in the sera of 73.6 and 48.8% of the patients, respectively. The extent of IgE binding to the 2-ME extract and phosphomannoproteins was well correlated with the fluorescence intensities estimated with the CAP system. Furthermore, the results obtained from the inhibition experiment with the CAP system indicated that the binding of IgE antibodies to Candida antigens is strongly inhibited by the phosphomannoprotein fraction and is an indication that the serum of the patients contained IgE antibodies specific to the cell wall phosphomannoproteins of C. albicans. Finally, an initial chemical analysis indicated that the epitopes for IgE antibodies on the phosphomannoproteins is a carbohydrate portion, since the ability of CAMP/A to inhibit the binding of IgE antibodies to the homologous CAMP/A was destroyed after oxidation by sodium periodate but not after digestion with proteinase K.

Daunomycin unfolds compactly packed DNA

Daunomycin is an antitumor antibiotic known to inhibit DNA replication and transcription. Although the inhibition is assumed to be caused by a direct interaction of the drug with DNA, the exact effect of daunomycin on the higher order DNA structure remains uncertain. We studied the effect of daunomycin on DNA compacted states using fluorescence and electron microscopies. Structural changes in individual DNA molecules were examined under the following conditions. T4 phage DNA (166 kbp) was first compacted by spermidine followed by the addition of daunomycin to the compacted DNA. A direct observation of individual single duplex DNAs by fluorescence microscopy indicated that daunomycin induced unfolding of the compacted DNA. Electron microscopic observation of the morphological changes of the higher order DNA structure supported the results obtained by fluorescence microscopy. We discuss here the mechanisms of the unfolding of the compacted structure following intercalation of daunomycin into DNA particularly in terms of the free energy.

Folding and aggregation of DNA chains induced by complexation with lipospermine: formation of a nucleosome-like structure and network assembly

Dioctadecylamidoglycylspermine (DOGS) is a cationic lipid vector capable of efficiently introducing DNA into various eukaryotic cells. We investigated the higher-order structure of the DNA/DOGS complex using fluorescence and electron microscopy. Our results show that the DNA/DOGS complex exhibits a nucleosome-like structure in which DNA wraps around an aggregate of DOGS molecules. In addition, DNA/DOGS complexes tend to associate with each other to form network structures. The resulting network assembly may play a role in effective gene transfection.

Effect of cilostazol, a cAMP phosphodiesterase inhibitor, on nitric oxide production by vascular smooth muscle cells

We investigated the effects of cilostazol, a cAMP phosphodiesterase inhibitor, on nitric oxide (NO) synthesis in cultured rat vascular smooth muscle cells. Incubation of the cultures with interleukin-1 beta (10 ng/ml) for 24 h caused a significant increase in the accumulation of nitrite, a stable metabolite of NO. Although cilostazol itself showed no effect on nitrite accumulation, it stimulated interleukin-1 beta-induced nitrite accumulation in a concentration-dependent manner (10(-8)-10(-5) M). This effect of cilostazol was completely abolished in the presence of NG-monomethyl-L-arginine, actinomycin D or dexamethasone. The cilostazol-induced nitrite production was accompanied by increased inducible NO synthase protein expression. In the presence of dibutyryl-cAMP, interleukin-1 beta-induced nitrite accumulation was further increased, but the stimulatory effect of cilostazol on nitrite accumulation was blunted. The effect of cilostazol was also abolished in the presence of Rp-8-bromoadenosine-3',5-cyclic monophosphorothioate, a competitive inhibitor of protein kinase A. Addition of cilostazol to the cultures significantly increased intracellular cAMP levels of vascular smooth muscle cells. These results indicate that cilostazol increases NO synthesis in interleukin-1 beta-stimulated smooth muscle cells, at least partially through a cAMP-dependent pathway.

Effects of a bradykinin receptor antagonist (HOE140) on taurocholate-induced acute pancreatitis in rats

The effect of a potent and long-acting bradykinin B2-receptor antagonist (HOE140) on acute pancreatitis induced by retrograde infusion of trypsin and taurocholate into the pancreatic duct was studied in rats. HOE140 was administered subcutaneously immediately before and 3 h after the induction of pancreatitis and the systemic blood pressure, ascites volume, serum amylase, 24-h survival rate, and pathology of the pancreas were evaluated. Plasma concentrations of bradykinin increased significantly 15 min after the induction of pancreatitis and decreased to basal levels at 90 min. HOE140 (0.1 mg/kg) alleviated hypotension developing immediately after the induction of pancreatitis and reduced the ascites volume. The 24-h survival rate in rats treated with 0.1 mg/kg HOE140 (70.3%) was significantly higher than that in controls (35.6%). Treatment with 0.01, 0.3, 1.0, and 3.0 mg/kg of HOE140, however, had no beneficial effect on the survival rate. Ascites volume, serum amylase, and pathology of the pancreas at 24 h were not improved by treatment with HOE140. These data suggest that HOE140 may improve the survival rate by maintaining hemodynamics in the early stage of experimental acute pancreatitis.

Alpha-adrenergic stimulation enhances inducible nitric oxide synthase expression in rat cardiac myocytes

We investigated the effects of alpha 1-adrenergic stimulation on nitric oxide (NO) production by cardiac myocytes. Incubation of cultured neonatal rat cardiac myocytes with interleukin-1 beta (IL-1 beta) caused a significant increase in the production of nitrite, a stable metabolite of NO. Addition of phenylephrine significantly augmented nitrite production by IL-1 beta-stimulated but not by unstimulated myocytes in a dose-dependent manner. The effect of phenylephrine was completely abolished in the presence of NG-monomethyl-L-arginine (L-NMMA) or actinomycin D. Northern blotting revealed increased inducible NO synthase mRNA accumulation in cardiac myocytes treated with IL-1 beta and phenylephrine compared with those treated with IL-1 beta alone. After protein kinase C activity was functionally depleted by treating cells with phorbol 12-myristate 13-acetate for 24 h, phenylephrine did not augment IL-1 beta-induced NO production. The effect of phenylephrine was also abolished in the presence of protein kinase C inhibitor calphostin C. These observations suggest that alpha 1-adrenergic stimulation causes an upregulation of cytokine-induced NO production by cardiac myocytes, which is mediated at least partially via activation of protein kinase C.

Adrenomedullin increases inducible nitric oxide synthase in rat vascular smooth muscle cells stimulated with interleukin-1

We investigated the effects of adrenomedullin on nitric oxide synthesis by measuring the production of nitrite, a stable metabolite of nitric oxide, in cultured rat vascular smooth muscle cells. Incubation of cultures with interleukin-1beta (10 ng/mL) for 24 hours caused a significant increase in nitrite generation. The interleukin-1beta-induced nitrite production by vascular smooth muscle cells was significantly increased by adrenomedullin in a dose-dependent manner (10(-10) to 10(-6) mol/L). This effect of adrenomedullin was significantly inhibited in the presence of Ng-monomethyl-L-arginine. The adrenomedullin-induced nitrite production by interleukin-1beta-stimulated cells was accompanied by increased inducible nitric oxide synthase mRNA accumulation. In the presence of the phosphodiesterase inhibitor isobutylmethylxanthine, interleukin-1beta-induced nitrite accumulation was further increased, but the effect of adrenomedullin was not additive or synergistic. Adrenomedullin dose dependently increased intracellular cAMP levels of vascular smooth muscle cells. These results indicate that adrenomedullin augments nitric oxide synthesis in interleukin-1beta-stimulated vascular smooth muscle cells, at least partially through a cAMP-dependent pathway.

Two cases of protothecosis in Nagoya, Japan

Two cases of protothecosis caused by Prototheca wickerhamii have been reported from Nagoya in a 12 year period in both cases the infection presented on the cheeks of otherwise healthy women. Biopsies showed numerous PAS positive staining organisms with the distinctive mulberry like endosporulation in the dermis. Prototheca wickerhamii was identified on sugar assimilation tests of colonies isolated from tissue on Sabouraud agar. Case 1 responded to 11 months of oral ketoconazole therapy. Case 2 might not respond to itraconazole. The source of the infections has not been identified.

Inflammatory cytokines and rat vascular tone

1. Experiments were performed to examine the effect of inflammatory cytokines, interleukin-2 (IL-2), IL-6 and IL-8, on the contractility of rat aorta. 2. Pretreatment of the endothelium-denuded aortic ring with IL-6 for 3 h caused a significant inhibition of its contraction (58.9 +/- 7.8%, n = 9, P < 0.01) when induced by 10(-6) mol/L phenylephrine. 3. On the other hand, IL-2 and IL-8 failed to show significant effects on the contractility of the aorta. 4. This inhibitory effect of IL-6 on phenylephrine-induced contraction showed dose-dependency, and completely disappeared in the presence of 10(-5) mol/L indomethacin. 5. In cultured rat vascular smooth muscle cells (VSMC), the release of 6-keto-prostaglandin F1alpha into the extracellular medium was significantly increased by exposure to IL-6, but not by exposure to IL-2 or IL-8. 6. IL-2, IL-6 and IL-8 showed no effects on the release of nitrite, a stable metabolite of nitric oxide (NO), from VSMC. 7. These results indicate that IL-6, not IL-2 or IL-8, is a potent inhibitor of the alpha-adrenergic-stimulated contraction of vascular smooth muscle and its action is mediated by the increased synthesis of prostacyclin rather than NO.

Effects of inflammatory cytokines on vascular tone

OBJECTIVE

To assess the direct effects of the inflammatory cytokines interleukin-2 (IL-2), interleukin-6 (IL-6) and interleukin-8 (IL-8) on vascular smooth muscle contraction.

METHODS

Smooth muscle contractility was studied in the thoracic aorta isolated from male Sprague-Dawley rats. Syntheses of cAMP and nitric oxide (NO) were investigated in cultured rat vascular smooth muscle cells (VSMC).

RESULTS

Pretreatment of the rings with IL-6 (10 ng/ml) for 180 min caused a significant inhibition of their contraction in response to 10(-5) M phenylephrine, wile Il-2 (10 ng/ml) and IL-8 (100 ng/ml) showed no significant effect on the contraction. The inhibitory effect of IL-6 exhibited a dose-dependency (0.1 approximately 10 ng/ml). In cultured rat VSMC, synthesis of cAMP was increased time-dependently by IL-6, while IL-2 and IL-8 failed to show any significant effects. IL-2, IL-6 and IL-8 did not affect the production of nitrite, a stable metabolite of NO, by VSMC.

CONCLUSIONS

IL-6, but not IL-2 and IL-8, is a potent inhibitor of vascular contraction, which effect is mediated through the increased cAMP synthesis.

Aldosterone inhibits nitric oxide synthesis in rat vascular smooth muscle cells induced by interleukin-1 beta

We investigated the effects of aldosterone on nitric oxide (NO) synthesis in vascular smooth muscle cells. We measured the production of nitrite, a stable metabolite of NO, and the expression of inducible NO synthase mRNA and protein in cultured rat vascular smooth muscle cells. Incubation of the cultures with interleukin-1 beta (10 ng/ml) for 24 h caused a significant increase in nitrite generation. The interleukin-1 beta-induced nitrite production by vascular smooth muscle cells was significantly inhibited by aldosterone in a dose (10(-9) approximately 10(-6) M)-dependent manner. Incubation with interleukin-1 beta for 12 approximately 24 h caused inducible NO synthase mRNA expression in vascular smooth muscle cells, whereas aldosterone had a suppressive effect on its expression. Aldosterone also decreased interleukin-1 beta-induced NO synthase protein accumulation. These results indicate that aldosterone inhibits NO synthesis under interleukin-1 beta-stimulated conditions in vascular smooth muscle cells.