PGC-1ß regulates HER2-overexpressing breast cancer cells proliferation by metabolic and redox pathways.

Breast cancer is a prevalent neoplastic disease among women worldwide which treatments still present several side effects and resistance. Considering that cancer cells present derangements in their energetic homeostasis, and that peroxisome proliferator-activated receptor- gamma coactivator 1 (PGC-1) is crucial for cellular metabolism and redox signaling, the main objective of this study was to investigate whether there is a relationship between PGC-1 expression, the proliferation of breast cancer cells and the mechanisms involved. We initially assessed PGC-1ß expression in complementary DNA (cDNA) from breast tumor of patients bearing luminal A, luminal B, and HER2-overexpressed and triple negative tumors. Our data showed that PGC-1ß expression is increased in patients bearing HER2-overexpressing tumors as compared to others subtypes. Using quantitative PCR and immunoblotting, we showed that breast cancer cells with HER2-amplification (SKBR-3) have greater expression of PGC-1ß as compared to a non-tumorous breast cell (MCF-10A) and higher proliferation rate. PGC-1ß expression was knocked down with short interfering RNA in HER2-overexpressing cells, and cells decreased proliferation. In these PGC-1ß-inhibited cells, we found increased citrate synthase activity and no marked changes in mitochondrial respiration. Glycolytic pathway was decreased, characterized by lower intracellular lactate levels. In addition, after PGC-1ß knockdown, SKBR-3 cells showed increased reactive oxygen species production, no changes in antioxidant activity, and decreased expression of ERRα, a modulator of metabolism. In conclusion, we show an association of HER2-overexpression and PGC-1ß. PGC-1ß knockdown impairs HER2-overexpressing cells proliferation acting on ERRα signaling, metabolism, and redox balance.

Poor prognosis indicators of type-2 diabetic COVID-19 patients.

Diabetes is associated with a worse prognosis and a high risk of morbidity and mortality in COVID-19 patients. We aimed to evaluate the main factors involved in the poor prognosis in diabetic patients. A total of 984 patients diagnosed with COVID-19 admitted to the hospital were included in this study. Patients were first divided into type-2 diabetic (DM+) and non-diabetic (DM-) groups. The participants were analyzed based on the National Early Warning Score (NEWS) and on the Quick-Sequential Organ Failure Assessment (qSOFA) to find the best prognostic risk score for our study. The DM+ and DM- groups were divided into non-severe and severe groups. Comparative and correlative analyses were used to identify the physiological parameters that could be employed for creating a potential risk indicator for DM+ COVID-19 patients. We found a poorer prognosis for the DM+ COVID-19 patients with a higher ICU admission rate, mechanical ventilation rate, vasopressor use, dialysis, and longer treatment times compared with the DM- group. DM+ COVID-19 patients had increased plasma glucose, lactate, age, urea, NEWS, and D-dimer levels, herein referred to as the GLAUND set, and worse prognosis and outcomes when compared with infected DM- patients. The NEWS score was a better indicator for assessing COVID-19 severity in diabetic patients than the q-SOFA score. In conclusion, diabetic COVID-19 patients should be assessed with the NEWS score and GLAUND set for determining their prognosis COVID-19 prognosis.

PPARγ expression is increased in systemic lupus erythematosus patients and represses CD40/CD40L signaling pathway.

Systemic lupus erythematosus (SLE) is a heterogeneous disease involving several immune cell types and pro-inflammatory signals, including the one triggered by binding of CD40L to the receptor CD40. Peroxisome-proliferator activated receptor gamma (PPARγ) is a transcription factor with anti-inflammatory properties. Here we investigated whether CD40 and PPARγ could exert opposite effects in the immune response and the possible implications for SLE. Increased PPARγ mRNA levels were detected by real-time PCR in patients with active SLE, compared to patients with inactive SLE PPARγ/GAPDH mRNA = 2.21 ± 0.49 vs. 0.57 ± 0.14, respectively (p < 0.05) or patients with infectious diseases and healthy subjects (p < 0.05). This finding was independent of the corticosteroid therapy. We further explored these observations in human THP1 and in SLE patient-derived macrophages, where activation of CD40 by CD40L promoted augmented PPARγ gene transcription compared to non-stimulated cells (PPARγ/GAPDH mRNA = 1.14 ± 0.38 vs. 0.14 ± 0.01, respectively; p < 0.05). This phenomenon occurred specifically upon CD40 activation, since lipopolysaccharide treatment did not induce a similar response. In addition, increased activity of PPARγ was also detected after CD40 activation, since higher PPARγ-dependent transcription of CD36 transcription was observed. Furthermore, CD40L-stimulated transcription of CD80 gene was elevated in cells treated with PPARγ-specific small interfering RNA (small interfering RNA, siRNA) compared to cells treated with CD40L alone (CD80/GAPDH mRNA = 0.11 ± 0.04 vs. 0.05 ± 0.02, respectively; p < 0.05), suggesting a regulatory role for PPARγ on the CD40/CD40L pathway. Altogether, our findings outline a novel mechanism through which PPARγ regulates the inflammatory signal initiated by activation of CD40, with important implications for the understanding of immunological mechanisms underlying SLE and the development of new treatment strategies.

A modified mouse-tail lymphedema model.

One of the main obstacles to studying the pathophysiology of lymphedema development is the lack of appropriate experimental models. Fol-lowing up on a mouse-tail method that has been described, we performed changes to the method which made it easier to perform in our hands and demonstrated similar results. Twenty C57Black mice were operated on using the previous tech-nique and euthanized after 3 or 6 weeks. Another twenty mice were submitted to the new technique developed in our laboratory and euthanized at the same time points. Tissue samples were collected from the proximal part of the tail (control) and from the distal part (lymphedema) for both mod-els. Animals in both operative groups developed marked edema in the distal part of the tail. This was characterized by lymph vessels dilation, edema, inflammatory cell infiltration, and adipose tissue deposition. Lymphedema was detected after 3 weeks in both models, reaching its maximum after 6 weeks. Adipocytes detected by histology (Oil red O staining) and molecular markers for adipogenesis, lymphangiogenesis and inflam-mation (lipin 1 and 2, SLP76, and F4-80) were demonstrated to be increased equally in both models. In conclusion, both models provide a reliable method to study lymphedema pathophys-iology. However, our modified technique is easier and faster to perform while still providing reliable and consistent results.

Risk factors for surgical site infection after surgery for esophageal perforation.

Esophageal perforations carry a high potential for morbidity and mortality. The prognosis depends on rapid and precise diagnosis and management. Surgical site infections (SSIs) are very common following the surgical treatment of esophageal lesions. We aimed identify significant risk factors for SSI after surgery for esophageal perforation via an historical cohort study including patients who underwent surgical management of esophageal perforation. The predictive variables were analyzed by bivariate analysis and multiple logistic regression. Eighty-one patients were studied during a 10-year period ending in 2004. The mean age was 42.6 years. In 44% of the patients the time interval between the perforation and surgery was up to 6 h and in 30% it was > 24 h. Associated lesions occurred in other cavities; 17% in the chest, 5% in the abdomen, 5% in the extremities, 4% in the spinal column and bone marrow and 2% in the face. There were grade I lesions in eight cases (10%), grade II in 64 cases (79%) and grade III in nine cases (11%). The mean time of surgery procedure was 117.2 min. The mean SSI was 7.99. SSIs occurred in 33 patients (41%). The risk factors for SSI following surgical management of esophageal perforation were: age > or = 50 years, time delay to treatment > 24 h, associated lesion in another cavity and Injury Severity Score > or = 15.

Poor prognosis indicators of type-2 diabetic COVID-19 patients

Diabetes is associated with a worse prognosis and a high risk of morbidity and mortality in COVID-19 patients. We aimed to evaluate the main factors involved in the poor prognosis in diabetic patients. A total of 984 patients diagnosed with COVID-19 admitted to the hospital were included in this study. Patients were first divided into type-2 diabetic (DM+) and non-diabetic (DM-) groups. The participants were analyzed based on the National Early Warning Score (NEWS) and on the Quick-Sequential Organ Failure Assessment (qSOFA) to find the best prognostic risk score for our study. The DM+ and DM- groups were divided into non-severe and severe groups. Comparative and correlative analyses were used to identify the physiological parameters that could be employed for creating a potential risk indicator for DM+ COVID-19 patients. We found a poorer prognosis for the DM+ COVID-19 patients with a higher ICU admission rate, mechanical ventilation rate, vasopressor use, dialysis, and longer treatment times compared with the DM- group. DM+ COVID-19 patients had increased plasma glucose, lactate, age, urea, NEWS, and D-dimer levels, herein referred to as the GLAUND set, and worse prognosis and outcomes when compared with infected DM- patients. The NEWS score was a better indicator for assessing COVID-19 severity in diabetic patients than the q-SOFA score. In conclusion, diabetic COVID-19 patients should be assessed with the NEWS score and GLAUND set for determining their prognosis COVID-19 prognosis.

Liver mitochondrial dysfunction and oxidative stress in the pathogenesis of experimental nonalcoholic fatty liver disease.

Oxidative stress and hepatic mitochondria play a role in the pathogenesis of nonalcoholic fatty liver disease. The aim of the present study was to evaluate the role of hepatic mitochondrial dysfunction and oxidative stress in the pathogenesis of the disease. Fatty liver was induced in Wistar rats with a choline-deficient diet (CD; N = 7) or a high-fat diet enriched with PUFAs-omega-3 (H; N = 7) for 4 weeks. The control group (N = 7) was fed a standard diet. Liver mitochondrial oxidation and phosphorylation were measured polarographically and oxidative stress was estimated on the basis of malondialdehyde and glutathione concentrations. Moderate macrovacuolar liver steatosis was observed in the CD group and mild liver steatosis was observed in the periportal area in the H group. There was an increase in the oxygen consumption rate by liver mitochondria in respiratory state 4 (S4) and a decrease in respiratory control rate (RCR) in the CD group (S4: 32.70 +/- 3.35; RCR: 2.55 +/- 0.15 ng atoms of O2 min-1 mg protein-1) when compared to the H and control groups (S4: 23.09 +/- 1.53, 17.04 +/- 2.03, RCR: 3.15 +/- 0.15, 3.68 +/- 0.15 ng atoms of O2 min-1 mg protein-1, respectively), P < 0.05. Hepatic lipoperoxide concentrations were significantly increased and the concentration of reduced glutathione was significantly reduced in the CD group. A choline-deficient diet causes moderate steatosis with disruption of liver mitochondrial function and increased oxidative stress. These data suggest that lipid peroxidation products can impair the flow of electrons along the respiratory chain, causing overreduction of respiratory chain components and enhanced mitochondrial reactive oxygen species. These findings are important in the pathogenesis of nonalcoholic fatty liver disease.

Oxidative stress as a signaling mechanism of the vascular response to injury: the redox hypothesis of restenosis.

The prominent role of redox processes in tissue injury and in vascular cell signaling suggest their involvement in the repair reaction to vessel injury, which is a key determinant of restenosis post-angioplasty. Experimental studies showed a protective effect of superoxide dismutase or antioxidants on vasospasm, neointimal thickening or remodeling after balloon injury. It was also shown that oxidized thiols induce chelatable metal-dependent amplification of the vascular repair reaction. Ongoing or completed clinical trials show a promising effect of the antioxidant probucol against restenosis. However, few studies addressed the molecular physiological mechanisms underlying the redox hypothesis of restenosis. We recently showed evidence for marked oxidative stress early after balloon injury, with superoxide production mediated primarily by non-endothelial NAD(P)H oxidase-type flavoenzyme(s). This effect was closely related to the degree of injury. There is evidence supporting a role for such early redox processes in apoptotic cell loss and NF-kappa B activation. We present new data on the time course of oxidative stress after balloon injury of intact rabbit iliac arteries. Our data show that despite substantial neointimal growth and lumen narrowing, superoxide production and glutathione levels are unaltered at day 14 and 28 after balloon injury. At day 7 after injury, the peak neointimal proliferation in this model, there was significant decrease of vascular superoxide dismutase activity, without clear evidence of spontaneous superoxide production. Thus, oxidative stress after injury is likely to be an early transient event, which parallels the inflammatory and proliferative phases of the vascular response. We propose that such early redox processes act as dose-dependent signal transducers of gene programs that affect the final repair.

Sorafenib prevents liver fibrosis in a non-alcoholic steatohepatitis (NASH) rodent model.

Liver fibrosis occurring as an outcome of non-alcoholic steatohepatitis (NASH) can precede the development of cirrhosis. We investigated the effects of sorafenib in preventing liver fibrosis in a rodent model of NASH. Adult Sprague-Dawley rats were fed a choline-deficient high-fat diet and exposed to diethylnitrosamine for 6 weeks. The NASH group (n=10) received vehicle and the sorafenib group (n=10) received 2.5 mg·kg(-1)·day(-1) by gavage. A control group (n=4) received only standard diet and vehicle. Following treatment, animals were sacrificed and liver tissue was collected for histologic examination, mRNA isolation, and analysis of mitochondrial function. Genes related to fibrosis (MMP9, TIMP1, TIMP2), oxidative stress (HSP60, HSP90, GST), and mitochondrial biogenesis (PGC1α) were evaluated by real-time quantitative polymerase chain reaction (RT-qPCR). Liver mitochondrial oxidation activity was measured by a polarographic method, and cytokines by enzyme-linked immunosorbent assay (ELISA). Sorafenib treatment restored mitochondrial function and reduced collagen deposition by nearly 63% compared to the NASH group. Sorafenib upregulated PGC1α and MMP9 and reduced TIMP1 and TIMP2 mRNA and IL-6 and IL-10 protein expression. There were no differences in HSP60, HSP90 and GST expression. Sorafenib modulated PGC1α expression, improved mitochondrial respiration and prevented collagen deposition. It may, therefore, be useful in the treatment of liver fibrosis in NASH.

Vascular oxidant stress early after balloon injury: evidence for increased NAD(P)H oxidoreductase activity.

Available evidence for oxidative stress after angioplasty is indirect or ambiguous. We sought to characterize the pattern, time course, and possible sources of free radical generation early after arterial balloon injury. Ex vivo injury performed in arterial rings in buffer with lucigenin yielded a massive oxygen-dependent peak of luminescence that decayed exponentially and was proportional to the degree of injury. Signals for injured vs. control arteries were 207. 1 +/- 17.9 (n = 13) vs 4.1 +/- 0.7 (n = 22) cpm x 10(3)/mg/min (p <. 001). Data obtained with 0.25 mmol/l lucigenin were validated with 0. 005-0.05 mmol/l lucigenin or the novel superoxide-sensitive probe coelenterazine (5 micromol/l). Gentle removal of endothelium prior to injury scarcely affected the amount of luminescence. Lucigenin signals were amplified 5- to 20-fold by exogenous NAD(P)H, and were >85% inhibited by diphenyliodonium (DPI, a flavoenzyme inhibitor). Antagonists of several other potential free radical sources, including xanthine oxidase, nitric oxide synthase, and mitochondrial electron transport, were without effect. Overdistension of intact rabbit iliac arteries in vivo (n = 7) induced 72% fall in intracellular reduced glutathione and 68% increase in oxidized glutathione, so that GSH/GSSG ratio changed from 7.93 +/- 2.14 to 0. 81 +/- 0.16 (p <.005). There was also 28.7% loss of the glutathione pool. Further studies were performed with electron paramagnetic resonance spectroscopy. Rabbit aortas submitted to ex vivo overdistension in the presence of the spin trap DEPMPO (5-diethoxy-phosphoryl-5-methyl-1-pyrroline-N-oxide, 100 mmol/l, n = 5) showed formation of radical adduct spectra, abolished by DPI or superoxide dismutase. Computer simulation indicated a mixture of hydroxyl and carbon-centered radical adducts, likely due to decay of superoxide adduct. Electrical mobility shift assays for NF-kappaB activation were performed in nuclear protein extracts from intact or previously injured rabbit aortas. Balloon injury induced early NF-kappaB activation, which was decreased by DPI. In conclusion, our data show unambiguously that arterial injury induces an immediate profound vascular oxidative stress. Such redox imbalance is likely accounted for by activation of vessel wall NAD(P)H oxidoreductase(s), generating radical species potentially involved in tissue repair.

The balloon catheter induces an increase in contralateral carotid artery reactivity to angiotensin II and phenylephrine.

1. The effects of balloon injury on the reactivity of ipsilateral and contralateral carotid arteries were compared to those observed in arteries from intact animals (control arteries). 2. Carotid arteries were obtained from Wistar rats 2, 4, 7, 15, 30 or 45 days after injury and mounted in an isolated organ bath. Reactivity to angiotensin II (Ang II), phenylephrine (Phe) and bradykinin (BK) was studied. Curves were constructed in the absence or presence of endothelium or after incubation with 10 microm indomethacin, 500 microm valeryl salicylate or 0.1 microm celecoxib. 3. Phe, Ang II and BK maximum effects (Emax) were decreased in ipsilateral arteries when compared to control arteries. No differences were observed among pD2 or Hill coefficient. 4. Emax to Phe (4 and 7 days) and to Ang II (15 and 30 days) increased in the contralateral artery. In addition, Phe or Ang II reactivity was not significantly different in aorta rings from control or carotid-injured animals. 5. The increased responsiveness of contralateral artery was not due to changes in carotid blood flow or resting membrane potential. The endothelium-dependent inhibitory component is not present in the contraction of contralateral arteries and it is not related to superoxide anion production. 6. Indomethacin decreased contralateral artery responsiveness to Phe and Ang II. Valeryl salicylate reduced the Ang II response in contralateral and control arteries. Celecoxib decreased the Phe Emax of contralateral artery. 7. In conclusion, decreased endothelium-derived factors and increased prostanoids appear to be responsible for the increased reactivity of contralateral arteries after injury.

Sorafenib prevents liver fibrosis in a non-alcoholic steatohepatitis (NASH) rodent model

Liver fibrosis occurring as an outcome of non-alcoholic steatohepatitis (NASH) can precede the development of cirrhosis. We investigated the effects of sorafenib in preventing liver fibrosis in a rodent model of NASH. Adult Sprague-Dawley rats were fed a choline-deficient high-fat diet and exposed to diethylnitrosamine for 6 weeks. The NASH group (n=10) received vehicle and the sorafenib group (n=10) received 2.5 mg·kg-1·day-1 by gavage. A control group (n=4) received only standard diet and vehicle. Following treatment, animals were sacrificed and liver tissue was collected for histologic examination, mRNA isolation, and analysis of mitochondrial function. Genes related to fibrosis (MMP9, TIMP1, TIMP2), oxidative stress (HSP60, HSP90, GST), and mitochondrial biogenesis (PGC1α) were evaluated by real-time quantitative polymerase chain reaction (RT-qPCR). Liver mitochondrial oxidation activity was measured by a polarographic method, and cytokines by enzyme-linked immunosorbent assay (ELISA). Sorafenib treatment restored mitochondrial function and reduced collagen deposition by nearly 63% compared to the NASH group. Sorafenib upregulated PGC1α and MMP9 and reduced TIMP1 and TIMP2 mRNA and IL-6 and IL-10 protein expression. There were no differences in HSP60, HSP90 and GST expression. Sorafenib modulated PGC1α expression, improved mitochondrial respiration and prevented collagen deposition. It may, therefore, be useful in the treatment of liver fibrosis in NASH.

Purine nucleotides reduce superoxide production by nitric oxide synthase in a murine sepsis model.

Sepsis involves a systemic inflammatory response of multiple endogenous mediators, resulting in many of the injurious and sometimes fatal physiological symptoms of the disease. This systemic activation leads to a compromised vascular response and endothelial dysfunction. Purine nucleotides interact with purinoceptors and initiate a variety of physiological processes that play an important role in maintaining cardiovascular function. The purpose of the present study was to investigate the effects of ATP on vascular function in a lipopolysaccharide (LPS) model of sepsis. LPS induced a significant increase in aortic superoxide production 16 h after injection. Addition of ATP to the organ bath incubation solution reduced superoxide production by the aortas of endotoxemic animals. Reactive Blue, an antagonist of the P2Y receptor, blocked the effect of ATP on superoxide production, and the nonselective P2Y agonist MeSATP inhibited superoxide production. Nitric oxide synthase (NOS) inhibition by L-NAME blocked vascular relaxation and reduced superoxide production in LPS-treated animals. In the presence of L-NAME there was no ATP effect on superoxide production. A vascular reactivity study showed that ATP increased maximal relaxation in LPS-treated animals compared to controls. The presence of ATP induced increases in Akt and endothelial NOS phosphorylated proteins in the aorta of septic animals. ATP reduces superoxide release resulting in an improved vasorelaxant response. Sepsis may uncouple NOS to produce superoxide. We showed that ATP through Akt pathway phosphorylated endothelial NOS and "re-couples" NOS function.

Treatment of hemorrhagic shock with hypertonic saline solution modulates the inflammatory response to live bacteria in lungs.

Shock and resuscitation render patients more susceptible to acute lung injury due to an exacerbated immune response to subsequent inflammatory stimuli. To study the role of innate immunity in this situation, we investigated acute lung injury in an experimental model of ischemia-reperfusion (I-R) followed by an early challenge with live bacteria. Conscious rats (N = 8 in each group) were submitted to controlled hemorrhage and resuscitated with isotonic saline (SS, 0.9% NaCl) or hypertonic saline (HS, 7.5% NaCl) solution, followed by intratracheal or intraperitoneal inoculation of Escherichia coli. After infection, toll-like receptor (TLR) 2 and 4 mRNA expression was monitored by RT-PCR in infected tissues. Plasma levels of tumor necrosis factor alpha and interleukins 6 and 10 were determined by ELISA. All animals showed similar hemodynamic variables, with mean arterial pressure decreasing to nearly 40 mmHg after bleeding. HS or SS used as resuscitation fluid yielded equal hemodynamic results. Intratracheal E. coli inoculation per se induced a marked neutrophil infiltration in septa and inside the alveoli, while intraperitoneal inoculation-associated neutrophils and edema were restricted to the interseptal space. Previous I-R enhanced lung neutrophil infiltration upon bacterial challenge when SS was used as reperfusion fluid, whereas neutrophil influx was unchanged in HS-treated animals. No difference in TLR expression or cytokine secretion was detected between groups receiving HS or SS. We conclude that HS is effective in reducing the early inflammatory response to infection after I-R, and that this phenomenon is achieved by modulation of factors other than expression of innate immunity components.

Increased endothelin-1 reactivity and endothelial dysfunction in carotid arteries from rats with hyperhomocysteinemia.

BACKGROUND AND PURPOSE: There are interactions between endothelin-1 (ET-1) and endothelial vascular injury in hyperhomocysteinemia (HHcy), but the underlying mechanisms are poorly understood. Here we evaluated the effects of HHcy on the endothelin system in rat carotid arteries. EXPERIMENTAL APPROACH: Vascular reactivity to ET-1 and ET(A) and ET(B) receptor antagonists was assessed in rings of carotid arteries from normal rats and those with HHcy. ET(A) and ET(B) receptor expression was assessed by mRNA (RT-PCR), immunohistochemistry and binding of [(125)I]-ET-1. KEY RESULTS: HHcy enhanced ET-1-induced contractions of carotid rings with intact endothelium. Selective antagonism of ET(A) or ET(B) receptors produced concentration-dependent rightward displacements of ET-1 concentration response curves. Antagonism of ET(A) but not of ET(B) receptors abolished enhancement in HHcy tissues. ET(A) and ET(B) receptor gene expressions were not up-regulated. ET(A) receptor expression in the arterial media was higher in HHcy arteries. Contractions to big ET-1 served as indicators of endothelin-converting enzyme activity, which was decreased by HHcy, without reduction of ET-1 levels. ET-1-induced Rho-kinase activity, calcium release and influx were increased by HHcy. Pre-treatment with indomethacin reversed enhanced responses to ET-1 in HHcy tissues, which were reduced also by a thromboxane A(2) receptor antagonist. Induced relaxation was reduced by BQ788, absent in endothelium-denuded arteries and was decreased in HHcy due to reduced bioavailability of NO. CONCLUSIONS AND IMPLICATIONS: Increased ET(A) receptor density plays a fundamental role in endothelial injury induced by HHcy. ET-1 activation of ET(A) receptors in HHcy changed the balance between endothelium-derived relaxing and contracting factors, favouring enhanced contractility.

Effects of mercury on the isolated perfused rat tail vascular bed are endothelium-dependent.

The effects of mercury on vascular smooth muscle results in vasoconstriction, but the mechanism of this action is not elucidated yet. To investigate this issue we examined the effects of HgCl(2) in the isolated rat tail vascular bed. The tail artery was dissected, cannulated, and perfused at a constant flow (2.5 ml/min) with Krebs solution plus EDTA 0.03 mM at 36 degrees C. After equilibration for 30 min the effects of increasing concentrations of HgCl(2) (0.5, 1, 2, 5, and 10 microM) on the perfusion pressure were investigated. Concentrations of HgCl(2), 2 microM and above, significantly increased perfusion pressure. Blockade of alpha receptors (prazosin 84 ng/ml) did not alter the responses to HgCl(2), suggesting that the metal does not induce the release of neurotransmitters from sympathetic nerve terminals. To investigate the possible role of endothelium on the vasoconstriction produced by HgCl(2), preparations were precontracted with 10(-7) M phenylepherine or perfused with 5 microM HgCl(2) for 20 min. Acetylcholine-vasodilated preparations precontracted with phenylepherine demonstrating the integrity of the endothelial nitric oxide-releasing mechanism. In contrast, after perfusion with 5 microM HgCl(2), the vasodilation produced by acetylcholine was abolished. In the presence of either phenylephrine or HgCl(2) the effects of sodium nitroprusside remained unchanged. Pretreatment with 30 microM indomethacin fully prevented the HgCl(2)-induced vasoconstriction. However, the endothelium-dependent vasodilation in response to acetylcholine was significantly reduced after indomethacin plus HgCl(2) treatment, meanwhile the vasodilation produced by nitroprusside remained unchanged. Pretreatment with L-arginine (1 mM) did not prevent the vasoconstriction induced by HgCl(2), nor did it restore the ability of acetylcholine to produce vasodilation, and it did not alter the response to sodium nitroprusside. The possibility of HgCl(2)'s actions mediated by the formation of free radicals was also investigated. The administration of 10 mM histidine significantly reduced the vasoconstrictor response if used before HgCl(2) treatment without improving the reduced vasodilation produced by acetylcholine. These results are consistent with the hypothesis that the vasoconstriction produced by HgCl(2) may be mediated by the formation of superoxide anions, stimulating the production of a COX-derived vasoconstrictor agent and by reducing the endothelial vasodilator activity.

Treatment of portal vein obstruction by percutaneous transhepatic angioplasty.

A case of extrahepatic portal hypertension and gastric variceal bleeding due to portal vein occlusion, most probably secondary to chronic pancreatitis, was treated by percutaneous transhepatic angioplasty. After the portal angioplasty there was marked clinical improvement, with control of the variceal bleeding and significant reduction of the pressure gradient within the portal system.

Vascular NAD(P)H oxidase is distinct from the phagocytic enzyme and modulates vascular reactivity control.

An NAD(P)H oxidase has been hypothesized to be the main source of reactive oxygen species (ROS) in vessels; however, questions remain about its function and similarity with the neutrophil oxidase. Therefore, vascular superoxide generation was measured by electron paramagnetic resonance spectroscopy using the spin-trap 5,5'-dimethly-pyrroline-N-oxide in aortas from wild-type (WT) and gp91(phox)-deficient mice (gp91(phox)-/-), which do not have a functioning neutrophil NADPH oxidase. There was no significant difference between radical adduct formation by WT or gp91(phox)-/- mouse aortas either at baseline or after stimulation with NADPH or NADH. Also, spin-adduct formation was identical in the 100,000-g pellets obtained from WT and gp91(phox)-/- mouse aortas. SOD mimetics and the flavoenzyme inhibitor diphenyleneiodonium blocked spin-adduct formation from both intact vessels and particulate fractions. Other pharmacological inhibitors of metabolic pathways involved in ROS generation had no effect on this phenomenon. To examine the role of this enzyme in vascular tone control, aortic rings were suspended in organ chambers and preconstricted with phenylephrine to reach half-maximal contraction. Exposure to NADPH elicited a 20% increase in vascular tone, which was decreased by SOD mimetics in a concentration-dependent manner, suggesting that superoxide was responsible for this phenomenon. NADH had no effect on vascular tone. Thus superoxide is generated in the vessel wall by an NAD(P)H-dependent oxidase, which modulates vascular contractile tone. This enzyme is structurally and genetically distinct from the neutrophil NADPH oxidase.

Blunt gastric injury. A multicentre experience.

A multicentre retrospective analysis of blunt gastric injuries from four trauma centres in Brazil was performed. From January 1982 to May 1996, 33 patients were found to have blunt gastric injury: 26 were male and the mean age was 26.2 years. The most frequent mechanism of injury was automobile versus pedestrian (17) followed by motor vehicle accidents (seven). Abdominal pain was the most common finding (29) and peritoneal signs were present in 14. There were 21 grade I, seven grade II, four grade III and one grade IV blunt gastric injuries. Simple suture was the treatment of choice in 24 patients, eight required no treatment, and only one patient underwent gastric resection. The liver and spleen were the most commonly associated injured organs. Two patients had isolated gastric injury. There were two gastric fistulae and both patients died. Overall morbidity and mortality was 12 (36%) and nine (27%), respectively. The ISS was higher in the non-survivor group (P=0.03) and the gastric organ injury score did not reach statistical significance when comparing survivors and non-survivors. We conclude that blunt gastric injury is uncommon and is associated with other injuries of greater magnitude, which generally influence mortality.