Vasopressin in septic shock: effects on pancreatic, renal, and hepatic blood flow

INTRODUCTION: Vasopressin has been shown to increase blood pressure in catecholamine-resistant septic shock. The aim of this study was to measure the effects of low-dose vasopressin on regional (hepato-splanchnic and renal) and microcirculatory (liver, pancreas, and kidney) blood flow in septic shock. METHODS: Thirty-two pigs were anesthetized, mechanically ventilated, and randomly assigned to one of four groups (n = 8 in each). Group S (sepsis) and group SV (sepsis/vasopressin) were exposed to fecal peritonitis. Group C and group V were non-septic controls. After 240 minutes, both septic groups were resuscitated with intravenous fluids. After 300 minutes, groups V and SV received intravenous vasopressin 0.06 IU/kg per hour. Regional blood flow was measured in the hepatic and renal arteries, the portal vein, and the celiac trunk by means of ultrasonic transit time flowmetry. Microcirculatory blood flow was measured in the liver, kidney, and pancreas by means of laser Doppler flowmetry. RESULTS: In septic shock, vasopressin markedly decreased blood flow in the portal vein, by 58% after 1 hour and by 45% after 3 hours (p < 0.01), whereas flow remained virtually unchanged in the hepatic artery and increased in the celiac trunk. Microcirculatory blood flow decreased in the pancreas by 45% (p < 0.01) and in the kidney by 16% (p < 0.01) but remained unchanged in the liver. CONCLUSION: Vasopressin caused marked redistribution of splanchnic regional and microcirculatory blood flow, including a significant decrease in portal, pancreatic, and renal blood flows, whereas hepatic artery flow remained virtually unchanged. This study also showed that increased urine output does not necessarily reflect increased renal blood flow.

Inverse thermodilution with conventional pulmonary artery catheters for the assessment of cerebral, hepatic, renal, and femoral blood flow

Assessment of regional blood flow changes is difficult in the clinical setting. We tested whether conventional pulmonary artery catheters (PACs) can be used to measure regional venous blood flows by inverse thermodilution (ITD). Inverse thermodilution was tested in vitro and in vivo using perivascular ultrasound Doppler (USD) flow probes as a reference. In anesthetized pigs, PACs were inserted in jugular, hepatic, renal, and femoral veins, and their measurements were compared with simultaneous USD flow measurements from carotid, hepatic, renal, and femoral arteries and from portal vein. Fluid boluses were injected through the PAC's distal port, and temperature changes were recorded from the proximally located thermistor. Injectates of 2 and 5 mL at 22 degrees C and 4 degrees C were used. Flows were altered by using a roller pump (in vitro), and infusion of dobutamine and induction of cardiac tamponade, respectively. In vitro: At blood flows between 400 mL . min-1 and 700 mL . min-1 (n = 50), ITD and USD correlated well (r = 0.86, P < 0.0001), with bias and limits of agreement of 3 +/- 101 mL . min-1. In vivo: 514 pairs of measurements had to be excluded from analysis for technical reasons, and 976 were analyzed. Best correlations were r = 0.87 (P < 0.0001) for renal flow and r = 0.46 (P < 0.0001) for hepatic flow. No significant correlation was found for cerebral and femoral flows. Inverse thermodilution using conventional PAC compared moderately well with USD for renal but not for other flows despite good in vitro correlation in various conditions. In addition, this method has significant technical limitations.

Elevated levels of endocannabinoids in chronic hepatitis C may modulate cellular immune response and hepatic stellate cell activation.

The endocannabinoid (EC) system is implicated in many chronic liver diseases, including hepatitis C viral (HCV) infection. Cannabis consumption is associated with fibrosis progression in patients with chronic hepatitis C (CHC), however, the role of ECs in the development of CHC has never been explored. To study this question, anandamide (AEA) and 2-arachidonoyl glycerol (2-AG) were quantified in samples of HCV patients and healthy controls by gas and liquid chromatography mass spectrometry. Fatty acid amide hydrolase (FAAH) and monoaclyglycerol lipase (MAGL) activity was assessed by [3H]AEA and [3H]2-AG hydrolysis, respectively. Gene expression and cytokine release were assayed by TaqMan PCR and ELISpot, respectively. AEA and 2-AG levels were increased in plasma of HCV patients, but not in liver tissues. Hepatic FAAH and MAGL activity was not changed. In peripheral blood mononuclear cells (PBMC), ECs inhibited IFN-γ, TNF-α, and IL-2 secretion. Inhibition of IL-2 by endogenous AEA was stronger in PBMC from HCV patients. In hepatocytes, 2-AG induced the expression of IL-6, -17A, -32 and COX-2, and enhanced activation of hepatic stellate cells (HSC) co-cultivated with PBMC from subjects with CHC. In conclusion, ECs are increased in plasma of patients with CHC and might reveal immunosuppressive and profibrogenic effects.

Effects of short-term overfeeding with fructose, fat and fructose plus fat on plasma and hepatic lipids in healthy men

The present study aimed to assess the effects of excess fat, fructose and fat-plus-fructose intakes on intrahepatocellular lipid (IHCL).

Garlic extract induces intestinal P-glycoprotein, but exhibits no effect on intestinal and hepatic CYP3A4 in humans

Garlic extracts have been shown to decrease drug exposure for saquinavir, a P-glycoprotein and cytochrome P450 3A4 substrate. In order to explore the underlying mechanisms and to study the effects of garlic on pre-systemic drug elimination, healthy volunteers were administered garlic extract for 21 days. Prior to and at the end of this period, expression of duodenal P-glycoprotein and cytochrome P450 3A4 protein were assayed and normalized to villin, while hepatic cytochrome P450 3A4 function and simvastatin, pravastatin and saquinavir pharmacokinetics were also evaluated. Ingestion of garlic extract increased expression of duodenal P-glycoprotein to 131% (95% CI, 105-163%), without increasing the expression of cytochrome P450 3A4 which amounted to 87% (95% CI, 67-112%), relative to baseline in both cases. For the erythromycin breath test performed, the average result was 96% (95% CI, 83-112%). Ingestion of garlic extract had no effect on drug and metabolite AUCs following a single dose of simvastatin or pravastatin, although the average area under the plasma concentration curve (AUC) of saquinavir decreased to 85% (95% CI, 66-109%), and changes in intestinal P-glycoprotein expression negatively correlated with this change. In conclusion, garlic extract induces intestinal expression of P-glycoprotein independent of cytochrome P450 3A4 in human intestine and liver.

Systemic and hepatic vein galectin-3 are increased in patients with alcoholic liver cirrhosis and negatively correlate with liver function

Recently we demonstrated higher galectin-3 in portal venous serum (PVS) compared to hepatic venous serum (HVS) in a small cohort of patients with normal liver function suggesting hepatic removal of galectin-3. Here, galectin-3 was measured by ELISA in PVS, HVS and systemic venous blood (SVS) of 33 patients with alcoholic liver cirrhosis and a larger cohort of 11 patients with normal liver function. Galectin-3 was cleared by the healthy but not the cirrhotic liver, and subsequently HVS and SVS galectin-3 levels were significantly increased in the patients with liver cirrhosis compared to controls. In healthy liver galectin-3 was produced by cholangiocytes and synthesis by hepatocytes was only observed in cirrhotic liver. Hepatic venous pressure gradient did not correlate with galectin-3 levels excluding hepatic shunting as the principal cause of higher SVS galectin-3. Galectin-3 was elevated in all blood compartments of patients with CHILD-PUGH stage C compared to patients with CHILD-PUGH stage A, and was higher in patients with ascites than patients without this complication. Galectin-3 was negatively associated with antithrombin-3 whose synthesis is reduced with worse liver function. Galectin-3 positively correlated with urea and creatinine, and PVS galectin-3 showed a negative association with creatinine clearance as an accepted measure of kidney function. To summarize in the current study systemic, portal and hepatic levels of galectin-3 were found to be negatively associated with liver function in patients with alcoholic liver cirrhosis and this may in part be related to impaired hepatic removal and/or increased synthesis in cirrhotic liver.

Interleukin-17 signaling in inflammatory, Kupffer cells, and hepatic stellate cells exacerbates liver fibrosis in mice

Interleukin (IL)-17 signaling has been implicated in lung and skin fibrosis. We examined the role of IL-17 signaling in the pathogenesis of liver fibrosis in mice.

Xanthohumol ameliorates atherosclerotic plaque formation, hypercholesterolemia, and hepatic steatosis in ApoE-deficient mice

SCOPE: Xanthohumol (XN), a prenylated antioxidative and anti-inflammatory chalcone from hops, exhibits positive effects on lipid and glucose metabolism. Based on its favorable biological properties, we investigated whether XN attenuates atherosclerosis in western-type diet-fed apolipoprotein-E-deficient (ApoE(-/-) ) mice. METHODS AND RESULTS: XN supplementation markedly reduced plasma cholesterol concentrations, decreased atherosclerotic lesion area, and attenuated plasma concentrations of the proinflammatory cytokine monocyte chemoattractant protein 1. Decreased hepatic triglyceride and cholesterol content, activation of AMP-activated protein kinase, phosphorylation and inactivation of acetyl-CoA carboxylase, and reduced expression levels of mature sterol regulatory element-binding protein (SREBP)-2 and SREBP-1c mRNA indicate reduced lipogenesis in the liver of XN-fed ApoE(-/-) mice. Concomitant induction of hepatic mRNA expression of carnitine palmitoyltransferase-1a in ApoE(-/-) mice-administered XN suggests increased fatty acid beta-oxidation. Fecal cholesterol concentrations were also markedly increased in XN-fed ApoE(-/-) mice compared with mice fed western-type diet alone. CONCLUSION: The atheroprotective effects of XN might be attributed to combined beneficial effects on plasma cholesterol and monocyte chemoattractant protein 1 concentrations and hepatic lipid metabolism via activation of AMP-activated protein kinase.

Tie2 receptor expression and phosphorylation in cultured cells and mouse tissues

Accumulating experimental evidence indicates that endothelial cell growth and blood vessel morphogenesis are processes that are governed by the activity of specifically expressed receptor tyrosine kinases (RTKs). We have used two new rat monoclonal antibodies (mAbs) to study the expression and phosphorylation of one such receptor, mouse Tie2 (tyrosine kinase that contains immunoglobulin-like loops and epidermal-growth-factor-similar domains 2]), in transfected cells, endothelioma cell lines and mouse tissues. The Tie2 receptor was found to be constitutively autophosphorylated when over-expressed in COS7 cells. In contrast, the endogenous Tie2 protein was not phosphorylated in endothelioma cell lines. However, in these cell lines, Tie2 could be induced to become tyrosine phosphorylated, and this activation was found to be independent of Tie1. Studying Tie2 receptor activity during angiogenesis in mouse development, the receptor was only weakly phosphorylated in the early postnatal mouse brain whereas a stronger activation could be detected in mouse embryos at day 10.5 post coitum.

Effects of dexamethasone on mRNA abundance of nuclear receptors and hepatic nuclear receptor target genes in neonatal calves

Hepatic nuclear receptors (NR), particularly constitutive androstane receptor (CAR) and pregnane X receptor (PXR), are involved in the coordinated transcriptional control of genes that encode proteins involved in the metabolism and detoxification of xeno- and endobiotics. A broad spectrum of metabolic processes are mediated by NR acting in concert with ligands such as glucocorticoids. This study examined the role of dexamethasone on hepatic mRNA expression of CAR, PXR and several NR target genes. Twenty-eight male calves were allotted to one of four treatment groups in a 2 x 2 arrangement of treatments: feed source (colostrum or milk-based formula) and glucocorticoid administration (twice daily intramuscular dexamethasone). Liver biopsies were obtained at 5 days of age. Real-time reverse transcription polymerase chain reaction was used to quantify mRNA abundances. No effects of feed source on mRNA abundances were observed. For the NR examined, mRNA abundance of both CAR and PXR in dexamethasone-treated calves was lower (p < 0.05) by 39% and 40%, respectively, than in control calves. Abundance of NR target genes exhibited a mixed response. SULT1A1 mRNA abundance was 39% higher (p < 0.05) in dexamethasone-treated calves compared with control calves. mRNA abundance of CYP2C8 tended also to be higher (+44%; p = 0.053) after dexamethasone treatment. No significant treatment effects (p > 0.10) were observed for mRNA abundances of CYP3A4, CYP2E1, SULT2A1, UGT1A1 or cytochrome P450 reductase (CPR). In conclusion, an enhanced glucocorticoid status, induced by pharmacological amounts of dexamethasone, had differential and in part unexpected effects on NR and NR target systems in 5-day-old calves. Part of the unexpected responses may be due the immaturity of NR and NR receptor target systems.

Effect of oral D-tagatose on liver volume and hepatic glycogen accumulation in healthy male volunteers

Standard toxicity tests with high levels of D-tagatose showed a reversible enlargement of the liver in Sprague-Dawley rats without increase of liver enzymes. The present study tests the hypotheses that partial substitution of dietary sucrose by D-tagatose for 28 days increases the volume of human liver and the concentration of liver glycogen. Twelve healthy, male volunteers were studied in a double-blind crossover study with ingestion of D-tagatose (3x15 g daily) and placebo (sucrose, 3x15 g daily) for periods of 28 days each. Liver volume and glycogen concentration have been determined by magnetic resonance (MR) imaging and spectroscopy, which were accompanied by routine medical examinations. MR examinations before and after the treatments revealed no effects (P>0.05) of treatment, period, or subject for changes in liver volume or glycogen concentration. A steady increase of liver volumes, independent of the D-tagatose or placebo intake, has been observed over the study in parallel with a slight increase in body weight. The treatment with D-tagatose was not associated with clinically relevant changes of the examined clinico-chemical and hematological parameters, including liver enzymes and uric acid.

Treatment of intestinal and hepatic mucormycosis in an immunocompromized child

During ALL chemotherapy, a 4-year-old patient presented with febrile neutropenia and abdominal pain. Ultrasound examinations were repeatedly normal. Computerized tomography on day 7 demonstrated appendicitis and multiple hepatic foci identified as mucormycosis (Absidia corymbifera). Successful outcome was achieved by aggressive re-surgery, long-term antifungal therapy with serum level-monitored posaconazole, and recovery of neutrophil counts. Considering the interference of posaconazole with CYP3A4, vincristine was administered during 72 hr posaconazole windows. Pediatric intestinal mucormycosis, still associated with a >70% case-fatality rate, calls for early imaging and surgery to establish the diagnosis, reduce the fungal mass, and provide a rationale for using posaconazole.

Quantification of global DNA methylation with infrared fluorescence in liver and muscle tissues of differentially fed boars

Methylation of cytosine residues at CpG sites is involved in various biological processes to control gene regulation and gene expression. Global DNA methylation is changed in different tumors and in cloned animals. Global DNA methylation can be accurately quantified by dot blot analysis with infrared (IR) fluorophores. Methylated lambda DNA was used as model DNA to develop and validate an immunochemical assay with IR fluorescence detection. Two different IR fluorophores were used, one to detect 5-methylcytosine and another to account for DNA loading. A sensitive infrared detection method was established which is suitable for accurate and reproducible quantification of global DNA methylation across a wide dynamic range. This method was subsequently employed to quantify global DNA methylation in liver and in muscle tissues of boars which have received either a control diet or a methyl supplemented diet in an ongoing study. A significant difference in global DNA methylation is indicated in muscle but not in liver tissue between the two groups of boars.

Congenital Hepatic Fibrosis in the Franches-Montagnes Horse Is Associated with the Polycystic Kidney and Hepatic Disease 1 (PKHD1) Gene

Congenital hepatic fibrosis has been described as a lethal disease with monogenic autosomal recessive inheritance in the Swiss Franches-Montagnes horse breed. We performed a genome-wide association study with 5 cases and 12 controls and detected an association on chromosome 20. Subsequent homozygosity mapping defined a critical interval of 952 kb harboring 10 annotated genes and loci including the polycystic kidney and hepatic disease 1 (autosomal recessive) gene (PKHD1). PKHD1 represents an excellent functional candidate as variants in this gene were identified in human patients with autosomal recessive polycystic kidney and hepatic disease (ARPKD) as well as several mouse and rat mutants. Whereas most pathogenic PKHD1 variants lead to polycystic defects in kidney and liver, a small subset of the human ARPKD patients have only liver symptoms, similar to our horses with congenital hepatic fibrosis. The PKHD1 gene is one of the largest genes in the genome with multiple alternative transcripts that have not yet been fully characterized. We sequenced the genomes of an affected foal and 46 control horses to establish a comprehensive list of variants in the critical interval. We identified two missense variants in the PKHD1 gene which were strongly, but not perfectly associated with congenital hepatic fibrosis. We speculate that reduced penetrance and/or potential epistatic interactions with hypothetical modifier genes may explain the imperfect association of the detected PKHD1 variants. Our data thus indicate that horses with congenital hepatic fibrosis represent an interesting large animal model for the liver-restricted subtype of human ARPKD.