Superoxide potently induces ceramide formation in glomerular endothelial cells.

Recent evidence suggests that the sphingolipid-derived second messenger ceramide and oxidative stress are intimately involved in apoptosis induction. Here we report that exposure of microcapillary glomerular endothelial cells to superoxide-generating substances, including hypoxanthine/xanthine oxidase and the redox cyclers DMNQ and menadione results in a dose-dependent and delayed increase in the lipid signaling molecule ceramide. Long-term incubation of endothelial cells for 2-30 h with either DMNQ or hypoxanthine/xanthine oxidase leads to a continuous increase in ceramide levels. In contrast, short-term stimulation for 1 min up to 1 h had no effect on ceramide formation. The DMNQ-induced delayed ceramide formation is dose-dependently inhibited by reduced glutathione, whereas oxidized glutathione was without effect. Furthermore, N-acetylcysteine completely blocks DMNQ-induced ceramide formation. All superoxide-generating substances were found to dose-dependently trigger endothelial cell apoptosis. In addition, glutathione and N-acetylcysteine also prevented superoxide-induced apoptosis and implied that ceramide represents an important mediator of superoxide-triggered cell responses like apoptosis.

Suppression of apoptosis by glucocorticoids in glomerular endothelial cells: effects on proapoptotic pathways.

Tumour necrosis factor-alpha (TNF-alpha)- and lipopolysaccharide (LPS)-induced apoptosis of bovine glomerular endothelial cells is now recognized as an important part in the pathogenesis of glomerulonephritis characterized by early mitochondrial cytochrome c release, mitochondrial permeability transition, Bak protein upregulation, Bcl-X(L) protein downregulation and caspase-3 activation. Co-treatment of cells with 10 nM dexamethasone and TNF-alpha or LPS blocked roughly 90% of apoptotic cell death in glomerular endothelial cells. The action of glucocorticoids could be documented in that they prevented all apoptotic markers such as DNA laddering, DNA fragmentation measured by the diphenylamine assay as well as morphological alterations. To mechanistically elucidate the action of glucocorticoids we evaluated whether glucocorticoids elicit a time-dependent effect. For dexamethasone, to maximally inhibit DNA fragmentation a preincubation period was not required. Even if dexamethasone was supplemented 6 h following TNF-alpha or LPS we observed a maximal inhibitory effect. Concerning its influence on TNF-alpha and LPS signal transduction, we found that dexamethasone only partially prevented cytochrome-c-release as a first sign of apoptotic cell death but efficiently blocked mitochondrial permeability transition. Moreover, TNF-alpha- and LPS-induced Bak upregulation, Bcl-X(L)-downregulation, and the activation of caspase-3-like proteases, measured fluorometrically using DEVD-AMC and PARP cleavage, were efficiently blocked by dexamethasone. We postulate that glucocorticoids exert their inhibitory action upstream of the terminal death pathways but downstream of primary receptor mediated signals by blocking pro-apoptotic signals pre- and/or post cytochrome c release and mitochondrial signalling.

Suppression and recovery of adrenal response after short-term, high-dose glucocorticoid treatment.

BACKGROUND: Suppression of the adrenal response is an unpredictable consequence of glucocorticoid treatment. To investigate the kinetics of the adrenal response after short-term, high-dose glucocorticoid treatment, we measured the adrenal response to the low-dose (1 microg) corticotropin stimulation test. METHODS: We studied 75 patients who received the equivalent of at least 25 mg prednisone daily for between 5 days and 30 days. After discontinuation of glucocorticoid treatment, 1 microg corticotropin was administered intravenously, and stimulated plasma cortisol concentrations were measured 30 min later. In patients with a suppressed response to 1 microg corticotropin, the test was repeated until stimulated plasma cortisol concentrations reached the normal range. FINDINGS: The adrenal response to 1 microg corticotropin was suppressed in 34 patients and normal in 41. Subsequent low-dose corticotropin tests showed a steady recovery of the adrenal response within 14 days. In two patients, the adrenal response remained suppressed for several months. There was no correlation between plasma cortisol concentrations and the duration or dose of glucocorticoid treatment. INTERPRETATION: Suppression of the adrenal response is common after short-term, high-dose glucocorticoid treatment. The low-dose corticotropin test is a sensitive and simple test to assess the adrenal response after such treatment.

Glucocorticoids potently block tumour necrosis factor-alpha- and lipopolysaccharide-induced apoptotic cell death in bovine glomerular endothelial cells upstream of caspase 3 activation.

1. Endothelial cell damage in glomeruli and kidney arterioles appears to play a pivotal role in glomerular inflammatory diseases. Glomerular endothelial cells, a specialized microvascular cell type involved in the regulation of glomerular ultrafiltration, die by apoptosis in response to tumour necrosis factor-alpha (TNF-alpha), TNF-alpha/basic fibroblast growth factor (bFGF), TNF-alpha/cycloheximide, and bacterial lipopolysaccharide (LPS). Apoptotic cell death is characterized by extensive DNA cleavage, DNA ladder formation, and characteristic morphological alterations. 2. In search for apoptosis-preventing signals, we identified glucocorticoids as potent death preventing factors. Co-treatment of cells with 10 nM dexamethasone and TNF-alpha, TNF-alpha/bFGF, TNF-alpha/cycloheximide, or LPS blocked roughly 90% of apoptotic cell death in glomerular endothelial cells. 3. Similarly to dexamethasone (TNF-alpha- and LPS-induced apoptosis are prevented with IC50 values of 0.8 and 0.9 nM, respectively), other synthetic and natural forms of glucocorticoids, such as fluocinolone, prednisolone, hydrocortisone, and corticosterone potently inhibited cell death with IC50 values of 0.2, 6, 50 and 1000 nM, for TNF-alpha and 0.7, 8, 100 and 500 nM for LPS, respectively. 4. Apart from glucocorticoids, mineralocorticoids such as aldosterone also blocked TNF-alpha/LPS-induced apoptosis (IC50 approximately 500 nM for TNF-alpha and approximately 500 nM for LPS), whereas sex hormones, i. e. beta-estradiol and testosterone remained without effect. 5. The protective effect of glucocorticoids (and mineralocorticoids) required glucocorticoid receptor binding as it could be antagonized by the glucocorticoid receptor antagonist RU-486. Concerning TNF-alpha and LPS signal transduction, we found that dexamethasone efficiently prevented TNF-alpha- and LPS-induced activation of caspase-3-like proteases. Therefore, we postulate inhibitory mechanisms upstream of terminal death pathways.

Tumor necrosis factor-alpha and lipopolysaccharide induce apoptotic cell death in bovine glomerular endothelial cells.

BACKGROUND: The glomerular endothelial cell is a specialized microvascular cell type involved in the regulation of glomerular ultrafiltration. During gram-negative sepsis, glomerulonephritis, and acute renal failure, bacterial lipopolysaccharide (LPS) and tumor necrosis factor-alpha (TNF-alpha) may cause severe cell damage. Our aim was to study and compare the direct effects of TNF-alpha and LPS on the induction of apoptosis in bovine glomerular endothelial cells. METHODS: Primary bovine glomerular endothelial cells were stimulated with TNF-alpha or LPS, and apoptotic cell death was investigated by DNA fragmentation analysis, morphological studies, measurement of cytochrome c efflux and mitochondrial permeability transition, Bak, Bad, Bax, Bcl-2, Bcl-xL protein expression, and caspase-3-like protease activity. RESULTS: TNF-alpha, as well as LPS, elicited apoptotic cell death both time and concentration dependently. Along with DNA ladder formation, we detected the formation of 50 kbp high molecular weight DNA fragments, nuclear condensation, and mitochondrial permeability transition. Concerning all parameters, LPS signaling proved to be more rapid than TNF-alpha. Mechanistically, TNF-alpha-induced cell death was preceded by an efflux of mitochondrial cytochrome c into the cytosol and, subsequently, by a marked increase in the proapoptotic protein Bak and a decrease in the anti-apoptotic Bcl-xL protein content. Comparable but more pronounced effects were seen with LPS. Later, caspase-3-like protease activity was first detectable after 10 hours and was continuously increased up to 24 hours in both TNF-alpha- and LPS-stimulated cells. Correspondingly, we detected an extended cleavage of the nuclear enzyme poly(ADP-ribose) polymerase. Caspase inhibitors Z-Asp-CH2-DCB and Z-VAD-fmk blocked both TNF-alpha- and LPS-induced apoptosis in a comparable manner. Only Z-Asp-CH2-DCB was able to block apoptotic cell death completely. CONCLUSION: Both bacterial LPS and TNF-alpha potently induced apoptotic cell death in glomerular endothelial cells. Direct endotoxin-induced apoptosis may therefore be relevant in the progression of acute renal failure, which is a frequent complication of gram-negative sepsis.

Nitric oxide stimulates chronic ceramide formation in glomerular endothelial cells.

Exposure of glomerular endothelial cells for 24 h to compounds releasing NO, including spermine-NO, MAHMA-NO, and S-nitroso-glutathione, results in a dose-dependent and delayed (after 24 h) increase in the lipid signaling molecule ceramide. This NO-induced stimulation occurs in a cGMP-independent fashion since the membrane-permeant cGMP analogue dibutyryl cGMP has no effect on chronic ceramide production. Short-term incubation of endothelial cells for 20 min reveals that NO and dibutyryl cGMP fail to stimulate an acute ceramide increase, whereas TNF-alpha, a well-known activator of sphingomyelinases, is able to acutely increase ceramide formation. Interestingly, N-oleoylethanolamine, an acidic ceramidase inhibitor, potentiates NO-induced chronic ceramide production, indicating that ceramide generation rather than ceramide metabolism is modulated by NO. Furthermore, NO-induced delayed ceramide formation is partially inhibited by the thiol-specific inhibitor iodoacetamide and the radical scavenger alpha-tocopherol, suggesting a regulatory role of thiol-containing enzymes and the involvement of a redox-sensitive mechanism. In addition, NO causes an increased DNA fragmentation in glomerular endothelial cells which is further enhanced by N-oleoylethanolamine and can be mimicked by exogenous ceramide. In summary, these results imply that ceramide represents an important mediator of NO-triggered chronic cell responses like apoptosis. Inhibition of ceramide synthesis may provide a new therapeutic approach to the treatment of pathological conditions involving increased NO formation.

[Neurosarcoidosis]. / Die Neurosarkoidose.

Signs and symptoms of neurosarcoidosis are variable and depend on location and size of granulomas. Clinical studies suggest a rate of 5% and autopsy results a rate of more than 25% of central nervous system (CNS) involvement in sarcoidosis. Statistical analysis of 57,789 patients admitted to the Department of Medicine in Lucerne over an 11-year period revealed 51 patients (0.9/1000) with the diagnosis of sarcoidosis. Six of these (12%) had sarcoidosis affecting the CNS. Neurosarcoidosis presented as: leptomeningeal granulomas, cranial nerve palsy, hypothalamic-pituitary syndrome, diabetes insipidus, pareses, paresthesia, pyramidal signs, dementia, urine retention, and asymptomatic granulomas. Neurosarcoidosis has predilections for the base of the brain, cranial nerves (facial nerve palsy is the most common) and meninges, but any part of the CNS may be affected. Therefore, the diagnosis of neurosarcoidosis may be extremely difficult, especially when it occurs as an isolated finding. Positive findings in transbronchial biopsy and lavage may demonstrate asymptomatic pulmonary involvement in as many as 50% of patients with neurosarcoidosis. Angiotensin-converting enzyme levels may be raised in the blood or cerebrospinal fluid in some 50% of cases. Kveim test has a low sensitivity in neurosarcoidosis and thus is of little use. Gallium uptake may demonstrate extracranial granuloma available for biopsy. All these tests, and also computed tomography and magnetic resonance imaging, may be helpful. However, when in selected cases with isolated CNS disease standard investigations are not conclusive, meningeal or cerebral biopsy may be required in order to exclude other causes such as other granulomatous disorders, tumor metastasis, lymphoma, vasculitis, Sjögren syndrome, infection, neurologic disease such as multiple sclerosis, or systemic diseases such as Whipple's disease. CNS involvement in the acute phase of the disease has a favorable prognosis, while chronic courses respond less well to therapy. Treatment is initiated most frequently with corticosteroids (0.5-1 mg/kg body weight/day or pulses of 1 g/day of methylprednisolone in severe cases). Improvement is seen within 1-2 months. Side effects of corticosteroids, aggressive disease or frequent recurrences may require other immunosuppressive drugs (methotrexate, azathioprine, chlorambucil, cyclosporine A). Cerebral irradiation may be successful in some cases when other treatments fail.

Feedback regulation of extracellular ATP-stimulated phosphoinositide hydrolysis by protein kinase C-alpha in bovine glomerular endothelial cells.

In glomerular endothelial cells, extracellular ATP stimulates a phospholipase C with subsequent hydrolysis of polyphosphoinositides and an increase in cytosolic free Ca2+ concentration ([Ca2+]i). Short-term (30 min) pretreatment of endothelial cells with 12-O-tetradecanoylphorbol 13-acetate (TPA), a potent activator of protein kinase C (PKC), decreases the ATP-stimulated phosphoinositide degradation and Ca2+ mobilization. However, this inhibition was lost after incubating the cells for four hours with TPA. Longer-term pretreatment (10 to 48 hr) even potentiated ATP-induced phosphoinositide breakdown and Ca2+ mobilization. In addition, pretreating the cells for 30 minutes with the specific PKC inhibitor Ro 31-8220 dose-dependently increased ATP-stimulated phosphoinositide hydrolysis, thus clearly indicating a regulatory role for PKC in the inositol lipid signaling pathway in glomerular endothelial cells. By using specific antibodies recognizing the different PKC isoenzymes, it is observed that glomerular endothelial cells express five isoenzymes: PKC-alpha, -delta, -epsilon, -zeta and -theta. No PKC-beta, -gamma, -eta and -mu isoenzymes were detected. On exposure to TPA, a complete depletion of PKC-alpha is observed within four hours. In contrast, PKC-epsilon was more resistant to phorbol ester, and even after 48 hours of TPA treatment, only 60% of PKC-epsilon was down-regulated. PKC-theta decreased very slowly from the cytosol (47% left after 24 hr of phorbol ester treatment) and translocated to the Triton X100-insoluble fraction. Moreover, PKC-delta and PKC-zeta were not significantly affected by 48 hours of phorbol ester incubation. Thus, only PKC-alpha is depleted with a kinetic that corresponds to the loss of feedback inhibition of ATP-stimulated phosphoinositide turnover. In the next step, [Ca2+]i changes were measured in single cells loaded with Fura-2 after microinjection of neutralizing PKC isoenzyme-specific antibodies. Injection of antibodies specific for PKC-alpha potently increased Ca2+ mobilization in response to ATP stimulation when compared to cells injected with buffer only or antibodies specific for PKC-epsilon. These results provide evidence that PKC-alpha mediates feedback inhibition of ATP-stimulated phosphoinositide hydrolysis in glomerular endothelial cells.

Nitric oxide donors induce apoptosis in glomerular mesangial cells, epithelial cells and endothelial cells.

Renal mesangial cells exposed to inflammatory cytokines produce high concentrations of nitric oxide (NO) which may exert cytotoxic actions. We report here that glomerular mesangial cells, endothelial cells and epithelial cells in culture are themselves targets for NO and undergo apoptotic cell death upon exposure to high concentrations of NO. NO generated from different NO-releasing compounds as well as NO-saturated solution induce apoptosis in all three cell types as demonstrated by internucleosomal DNA fragmentation, an enrichment of cytosolic DNA/histone complexes, an increasing number of cellular 3'-OH-fragmented DNA ends and typical nuclear chromatin condensation. Induction of apoptosis was found to be dependent on protein synthesis and is preceded by expression of the tumour suppressor gene product p53 in mesangial cells. Induction of inducible NO synthase in mesangial cells by interleukin-1 beta leads to excessive formation of NO by the cells as measured by nitrite production. However, there was no evidence for apoptotic changes in mesangial cells triggered by endogenously produced NO. Co-cultures of glomerular endothelial or epithelial cells with interleukin-1 beta-activated mesangial cells expressing inducible NO synthase do not show apoptotic alterations in endothelial or epithelial cells. Moreover, preincubation of mesangial cells with interleukin-1 beta protects the cells from apoptosis induced by subsequent addition of exogenous NO thus suggesting that interleukin-1 beta not only triggers the expression of inducible NO synthase and massive NO formation but simultaneously stimulates a protecting principle in the cells. In summary, these results suggest that exogenous NO can induce apoptosis in all three types of intrinsic glomerular cells. However, whether endogenously produced NO can fulfil this function critically depends on a balance between a yet to be defined protective mechanism and inducible NO synthase expression in mesangial cells in response to interleukin-1 beta and eventually other inflammatory cytokines.

[Skin and hair]. / Haut und Haar.

Data deriving from comprehensive hospital monitoring systems suggest that drug-induced skin effects occur in 2-5% of patients receiving any drug medication. Exanthematous (maculopapular) reaction (75%) and urticaria with/without angioedema (30%) are the most frequent of all cutaneous reactions to drugs. The incidence of cutaneous reactions relates to the quantity of the drugs which is prescribed and consumed worldwide. Thus penicillin, sulfonamides and nonsteroidal antiinflammatory drugs show the highest rate of cutaneous side effects. Drug reactions may be classified as either predictable (e.g. chemotherapy-induced alopecia) or unpredictable. Unpredictable side effects of drugs may be the result of allergic (type I to IV) or non-allergic reactions. Hereditary and acquired enzyme deficiency and variations in metabolic pathway may delay drug metabolism and cause nonallergic, toxic side effects. Such a mechanism is known to occur in patients with a low acetylation rate under hydralazine, INH or sulfonamide treatment. Some immunologic although nonallergic factors may facilitate eruptions in patients with infectious mononucleosis under ampicillin medication and in AIDS patients on co-trimoxazole therapy. When a cutaneous drug reaction is diagnosed, withdrawal of the drug is recommended. In instances in which patients display mild drug eruptions and no alternative therapy is available, the drug may be continued. However, it should be kept in mind that mild morbiliform eruption is often the initial presentation of toxic epidermal necrolysis. In AIDS patients sulfonamides most frequently have been implicated as a risk factor for the development of toxic epidermal necrolysis. In other than type 1 hypersensitivity reactions, skin testing and in vitro tests have low sensitivity and specificity.

Prevention of cancellous bone loss but persistence of renal bone disease despite normal 1,25 vitamin D levels two years after kidney transplantation.

Osteopenia has been observed to occur frequently after renal transplantation. The present study was undertaken to assess whether an immunosuppressive regimen combining cyclosporine with no or the lowest possible maintenance doses of glucocorticoid may prevent osteopenia after kidney transplantation. Thirty-four patients were prospectively followed for two years. Serial blood drawings were done for determination of serum indices of calcium and bone metabolism and an iliac crest bone biopsy was performed at time of transplantation. A second bone biopsy was done in 20 patients during the second year of observation. Creatinine clearance was 56 +/- 6 ml/min one year and 46 +/- 6 ml/min two years after transplantation. Serum parathyroid hormone levels were elevated in 24 patients at time of grafting, decreased significantly thereafter, but remained above the normal range. Ten patients had low or normal serum parathyroid hormone levels at time of transplantation and showed a significant increase after grafting. Two years after transplantation, the mean cumulative dose of prednisone was 5.9 +/- 0.5 g. After the first six months, 30-40% of the patients were not on maintenance doses of steroids. None of the patients experienced fractures, and cancellous bone volume was within or above the normal range in all repeat bone biopsies. It is of note that metabolic bone abnormalities did not resolve 1-2 years after transplantation despite normalization of serum 1,25 vitamin D levels. The histologic abnormalities at the time were consistent with the bone findings in renal failure suggesting resistance of bone to normal circulating levels of 1,25 vitamin D.

Proliferative mechanisms in kidney cells.

The activation of the mitogen-activated protein kinase cascade is one of the major signalling pathways by which growth factors transmit their mitogenic messages from the cell membrane to the nucleus. Two major breakthroughs reported in the past months are the cross-communication between the mitogen-activated protein kinase cascade and the cAMP-protein kinase A signal pathway, and the role of alpha- and beta gamma-complexes of heterotrimeric G proteins in activating the mitogen-activated protein kinase pathway. These signalling strategies have now also been demonstrated in renal mesangial cells. Another important step has been the identification of a candidate gene for polycystic kidney disease. Knowledge of the molecular mechanisms of action of growth factors in the kidney will promote greatly our understanding of the aetiology of renal disease.

ATP stimulates Ca2+ mobilization by a nucleotide receptor in glomerular endothelial cells.

The present study investigates ATP effects on Ca2+ mobilization in bovine glomerular endothelial cells (GEC) and the receptors mediating ATP response. Extracellular ATP stimulated a rise in inositol 1,4,5-trisphosphate and cytosolic free Ca2+ concentration ([Ca2+]i) in a dose-dependent manner. Extracellular Ca2+ depletion did not prevent [Ca2+]i rise. ATP effects were not mediated by P1, P2x, and P2t purinoceptors, since the P1 receptor agonist adenosine and the P2x receptor agonist [alpha,beta-CH2]ATP had no effect on inositol 1-monophosphate (IP) formation and Ca2+ mobilization and ATP does not activate P2t receptors. The P2y receptor antagonist reactive blue (10(-3) M) had little inhibitory effect on ATP (10(-5) M)-stimulated IP formation (15.6 +/- 4.2%) and Ca2+ rise (7.0 +/- 3.0%). According to the classification of purinoceptors, ATP is less potent than 2-methylthioadenosine 5'-triphosphate (2-MeS-ATP) in stimulating P2y receptors. In GEC, however, the rank order of potency in stimulating IP and [Ca2+]i rise was ATP > 2-MeS-ATP > ADP. The pyrimidine nucleotide UTP (10(-3) M) induced maximal IP formation (653 +/- 37%) and Ca2+ mobilization (591 +/- 22 nM) similar to ATP (IP 647 +/- 27%; [Ca2+]i 583 +/- 15 nM). At submaximal (10(-5) M) but not at maximal (10(-3) M) doses ATP and UTP effects were additive. ATP and UTP induced specific cross-desensitization. It is concluded that the purinergic nucleotide ATP and pyrimidine nucleotide UTP mediate their effects by a common nucleotide receptor. This receptor differs from P2z and P2y1 receptors, since by definition UTP does not activate these receptors.(ABSTRACT TRUNCATED AT 250 WORDS)

Atrial natriuretic peptide and cGMP inhibit Na+/H+ antiporter in vascular smooth muscle cells in culture.

The aim of the present paper was to study the mechanisms of the inhibitory effect of atrial natriuretic peptide (ANP) on the sustained contraction phase of vascular smooth muscle cells (VSMC). Specifically, the potential role of ANP on the Na+/H+ antiporter and Na+ transport systems was investigated. Both ANP and 8-bromo cGMP inhibited 22Na+ uptake and decreased intracellular Na ([Na+]i) in VSMC, an effect that was mimicked by the specific Na+/H+ antiporter inhibitor, hexamethylen amiloride (HMA). The effect of ANP was not additive with HMA, therefore suggesting that both inhibit the same 22Na+ transport pathway. On the other hand, the inhibition of 22Na+ accumulation by ANP was additive with the inhibition by furosemide or bumetanide, thus suggesting that both drugs act on different Na+ exchange systems. In HEPES-buffered medium, ANP, cGMP, and HMA significantly inhibited the AVP-induced intracellular alkalinization, an effect which was associated with significant inhibition of the AVP-induced shape change. In bicarbonate buffered medium, ANP and cGMP decreased the pH level below the baseline after application of AVP, and an inhibition by ANP and cGMP of AVP-induced VSMC shape change was also observed. The recovery of cellular pH after three different types of acid load, namely, ammonium chloride pulse, nigericin clamp and lowering of extracellular pH, was significantly decreased by ANP and cGMP. Taken together, these results indicate that ANP/cGMP inhibit the activity of the Na+/H+ antiporter in VSMC, either in hormone- or pH-stimulated conditions.

Cytokine-stimulated secretion of group II phospholipase A2 by rat mesangial cells. Its contribution to arachidonic acid release and prostaglandin synthesis by cultured rat glomerular cells.

Potent pro-inflammatory cytokines, such as interleukin 1 (IL-1) or tumor necrosis factor (TNF) alpha have been found to increase group II phospholipase A2 (PLA2) synthesis and secretion by mesangial cells. In all cases 85-90% of the enzyme is secreted from the cells and a parallel increase in prostaglandin (PG)E2 synthesis is observed. We report here that co-incubation with a monoclonal antibody that specifically binds and neutralizes rat group II PLA2 attenuates IL-1 beta and TNF alpha-stimulated PGE2 production by 45% and 52%, respectively. CGP43182, a specific inhibitor of group II PLA2, potently blocks mesangial cell group II PLA2 in vitro with a half-maximal inhibitory concentration (IC50) of 1.5 microM, while only slightly affecting mesangial cell high molecular weight PLA2. CGP 43182 markedly attenuates IL-1 beta- and TNF alpha-stimulated PGE2 synthesis in intact mesangial cells with IC50's of 1.3 and 1.0 microM, respectively. PLA2 secreted from cytokine-stimulated mesangial cells was purified to homogeneity. Addition of the purified enzyme to unstimulated mesangial cells causes a marked release of arachidonic acid and a subsequent increased synthesis of PGE2. Moreover, addition of purified PLA2 to a cloned rat glomerular epithelial cell line and cultured bovine glomerular endothelial cells augmented both arachidonic acid release and PGE2 synthesis, with the endothelial cells being especially sensitive. Thus, cytokine-triggered synthesis and secretion of group II PLA2 by mesangial cells contributes, at least in part, to the observed synthesis of PGE2 that occurs in parallel to the enzyme secretion. Furthermore, extracellular PLA2 secreted by mesangial cells is able to stimulate arachidonic acid release and PGE2 synthesis by the adjacent endothelial and epithelial cells. These data suggest that expression and secretion of group II PLA2 triggered by pro-inflammatory cytokines may crucially participate in the pathogenesis of inflammatory processes within the glomerulus.

[Hypertensive crisis]. / Die hypertensive Krise.

Hypertensive crisis is a life-threatening situation caused by acute elevation of blood pressure. The rise in blood pressure is very rapid and thus overwhelms protective adaptive mechanisms in the arterioles which occur under physiological conditions. Endothelial damage results. Focal vessel wall ischemia, inappropriate constriction and dilatation of arterioles, and increase in vascular permeability develop and cause functional disturbances of the heart, central nervous system or kidneys. Without immediate treatment, irreversible organ damage results due to ischemia and hemorrhage. The goal of therapy is to lower blood pressure by 25% within one hour. Blood pressure should be maintained at this level for 24 hours. Thereafter, blood pressure may be reduced by an additional 25% or to 180/100 mm Hg. Initial reduction in blood pressure by 55% may provoke irreversible end organ ischemia and infarction although blood pressure still may be well above the normal range. Most frequently, hypertensive crisis is treated with sodium nitroprusside as it allows controlled reduction in blood pressure due to its very rapid onset but short duration of action. Cyanide toxicity may develop in patients treated with high doses of sodium nitroprusside or with renal or kidney failure. Other agents used may have disadvantages such as unpredictable antihypertensive effects (calcium channel blockers, angiotensin converting enzyme inhibitor [ACEI]), tachycardia (calcium channel blockers, phentolamine, dihydralazine) or reduced renal blood flow (betablocker, ACEI).

Divergent effects of acute and chronic ethanol exposure on contraction and Ca2+ mobilization in cultured vascular smooth muscle cells.

In cultured rat vascular smooth muscle cells (VSMC), acute preincubation of 100 mmol/L ethanol for 30 min attenuated the number of contracting cells in response to (10(-7) mol/L) arginine vasopressin (AVP) (P < .01). In contrast, VSMC cultured chronically for 3 days in medium supplemented with 100 mmol/L ethanol enhanced (10(-7) mol/L) AVP-induced shape change (P < .01). Specific 3H-AVP binding to VSMC after acute or chronic exposure to 100 mmol/L ethanol did not differ from those of control experiments. Acute ethanol pretreatment attenuated basal, 10(-7) mol/L AVP-, 65 mmol/L K(+)-stimulated Ca2+ uptake, in a dose-dependent manner. In contrast, 100 mmol/L ethanol for 4 days enhanced the (P < .001) AVP- 10(-7) mol/L and (P < .01) 65 mmol/L K(+)-stimulated 45Ca2+ uptake. Acute ethanol exposure inhibited and chronic ethanol administration enhanced Ca2+ uptake stimulated by 6 x 10(-7) mol/L Bay K 8644, an activator of voltage-sensitive Ca2+ channels. Nifedipine, a blocker of these Ca2+ channels, diminished AVP-stimulated (P < .02) and K(+)-induced (P < .001) Ca2+ uptake more potently in VSMC pretreated for 4 days with 100 mmol/L ethanol than in control cells. Acute ethanol preexposure for 30 min attenuated AVP-stimulated inositol trisphosphate (IP3) formation (P < .05) and the rise in cytosolic free Ca2+ ([Ca2+]i) (P < .01). In contrast, chronic ethanol-treated VSMC enhanced IP3 formation (P < .05) and the rise in [Ca2+]i (P < .01) in response to AVP.(ABSTRACT TRUNCATED AT 250 WORDS)