New method of cardiac output measurement using ultrasound velocity dilution in rats.

The aim of this study was to validate a new technique for the measurement of cardiac output (CO) based on ultrasound and dilution (COUD) in anesthetized rats. A transit time ultrasound (TTU) probe was placed around the rat carotid artery, and ultrasound velocity dilution curves were generated on intravenous injections of saline. CO by COUD were calculated from the dilution curves for normal and portal hypertensive rats in which CO was known to be increased. COUD was compared with the radiolabeled microsphere method and with direct aortic TTU flowmetry for baseline CO and drug-induced CO variations. CO in direct aortic TTU flowmetry was the ascending aorta blood flow measured directly by TTU probe (normal use of TTU flowmetry). The reproducibility of COUD within the same animal was also determined under baseline conditions. COUD detected the known CO increase in portal hypertensive rats compared with normal rats. CO values by COUD were correlated with those provided by microsphere technique or direct aortic TTU flowmetry (adjusted r = 0.76, P < 10(-4) and r = 0.79, P < 0.05, respectively). Baseline CO values and terlipressin-induced CO variations were detected by COUD and the other techniques. Intra- and interobserver agreements for COUD were excellent (intraclass r = 0.99 and 0.98, respectively). COUD was reproducible at least 10 times in 20 min. COUD is an accurate and reproducible method providing low-cost, repetitive CO measurements without open-chest surgery. It can be used in rats as an alternative to the microsphere method and to direct aortic flowmetry.

New quantitative assay of hepatitis B and C viruses by competitive PCR using alternative internal sequences.

A competitive PCR was developed for quantitation of hepatitis B virus (HBV) DNA and hepatitis C virus (HCV) RNA, alternatively, using only two constructions containing both priming sites. DNAs corresponding to the HBV-S gene and the HCV-5' non-coding region were introduced into distinct plasmids. HBV plasmid was used as a standard for HBV-DNA quantitation, in competition with the HCV plasmid as internal control. HBV and HCV plasmids also served as template for transcription of HBV-RNA, and HCV-RNA, which was used as internal control and standard, respectively, in competition for HCV-RNA quantitation. The analyzed samples for HBV and HCV quantitation were processed in the same way in competition with the internal controls and to the respective calibration curves obtained by serial dilutions of the mimic standard. This method showed very good specificity and sensitivity, allowing absolute quantitation in a large linear range from 5 viral genomic copies per assay up to 10(6) copies, in sera of chronically HBV and HCV infected patients, as well as in supernatants of cell cultures inoculated with these viruses.

Human cytomegalovirus DNA kinetics using a novel HCMV DNA quantitative assay in white blood cells of immunocompromised patients under Ganciclovir therapy.

The clearance of human cytomegalovirus (HCMV) was evaluated in infected patients under Ganciclovir (GCV) treatment, using a novel HCMV DNA quantitation assay (HCMV DNA hybrid capture system, Murex Diagnostics). Peripheral white blood cells (WBC) from whole blood specimens of seven AIDS patients, three kidney and two allogeneic bone marrow transplant (BMT) recipients suffering from HCMV disease, were assessed by this method. HCMV DNA 50 and 90% mean clearances were observed at 2.11 +/- 1.97 and 6.22 +/- 4.31 days, respectively, after initial GCV treatment. The viral DNA kinetics were correlated with positive and negative pp65 antigenaemia and viral blood culture. Two-fold higher clearances and initial DNA levels were observed in the AIDS group compared to the transplant group. Neither clinical nor virological relapses were observed under GCV treatment. HCMV DNA quantitation in WBC appears well adapted for a therapeutic follow up of patients with HCMV disease.

Measurement of collateral circulation blood flow in anesthetized portal hypertensive rats.

AIMS: The aim of this study was to develop a technique to measure collateral blood flow in portal hypertensive rats. METHODS: Morphological techniques included inspection, casts and angiographies of portosystemic shunts. The main hemodynamic measurements were splenorenal shunt blood flow (transit time ultrasound method), percentage of portosystemic shunts and regional blood flows (microsphere method). In study 1, a model of esophageal varices was developed by ligating the splenorenal shunt. In study 2, morphological studies of the splenorenal shunt were performed in rats with portal vein ligation. In study 3, the relationship between splenorenal shunt blood flow with percentage of portosystemic shunts was evaluated in dimethylnitrosamine cirrhosis. In study 4, secondary biliary, CCl4 and dimethylnitrosamine cirrhosis were compared. In study 5, rats with portal vein ligation received acute administration of octreotide. In study 6, rats with dimethylnitrosamine cirrhosis received acute administration of vapreotide. RESULTS: Blood flow of para-esophageal varices could not be measured. SRS blood flow was correlated with the mesenteric percentage of portosystemic shunts (r = 0.74, P < 0.05), splenic percentage of portosystemic shunts (r = 0.54, P < 0.05) and estimated portosystemic blood flow (r = 0.91, P < 0.01). Splenorenal shunt blood flow was 6 to 12 times higher in portal hypertensive rats, e.g., in portal vein ligated rats: 2.8 +/- 2.7 vs 0.3 +/- 0.1 mL.min-1 in sham rats (P < 0.01), and was similar in the different cirrhosis models but was higher in portal vein ligated rats than in cirrhotic rats (1.2 +/- 0.7 vs 0.6 +/- 0.6 mL.min-1.100 g-1, P = 0.05). Octreotide significantly decreased splenorenal shunt blood flow: -23 +/- 20% (P < 0.01) vs -6 +/- 8% (not significant) in placebo rats. The variation of splenorenal shunt blood flow after vapreotide was significant but not that of the splenic percentage of portosystemic shunts compared to placebo. CONCLUSIONS: The splenorenal shunt is the main portosystemic shunt in rats. The measurement of splenorenal shunt blood flow is easy, accurate and reproducible and should replace the traditional measurement of the percentage of portosystemic shunts in pharmacological studies.

Effects of octreotide on intestinal transit and bacterial translocation in conscious rats with portal hypertension and liver fibrosis.

In cirrhosis, delayed intestinal transit may be responsible for increased endoluminal bacterial overgrowth and increased bacterial translocation. Octreotide has been reported to reduce intestinal transit. Therefore, we evaluated whether octreotide administration influences bacterial translocation in a model of liver fibrosis secondary to dimethylnitrosamine (DMNA) administration. Twenty-nine conscious rats were randomly assigned to three groups (sham rats + placebo as controls, DMNA + placebo, DMNA + octreotide, 1.5 microg/kg thrice daily subcutaneously), and including portal pressure, intestinal transit (radioactive method), and bacterial translocation were measured. Three of four variables measuring intestinal transit suggested a significant delay in intestinal transit in DMNA rats compared to controls (eg, cumulated radioactivity 50%: controls: 5.3+/-1.5, DMNA + placebo: 3.2+/-1.2, DMNA + octreotide: 2.7+/-1.9, P < 0.01). This delay tended to be enhanced by octreotide but the effect was only significant with one of the intestinal transit variables. Bacterial translocation was significantly increased in DMNA rats compared to controls but octreotide did not increase translocation [eg, germ count (log) in lymph nodes: controls: 3.1+/-3.6, DMNA + placebo: 12.3+/-4.4, DMNA + octreotide: 10.6+/-6.0, P < 0.001]. There was no significant correlation of portal pressure, intestinal transit, and bacterial translocation in this study. In conclusion, our results show that, although octreotide worsens delayed intestinal transit, it has no influence on the level of bacterial translocation.

Novel DNA assay for cytomegalovirus detection: comparison with conventional culture and pp65 antigenemia assay.

We compared conventional cytomegalovirus (CMV) isolation, rapid viral culture, a CMV pp65 antigenemia assay, and a novel CMV DNA hybrid capture system (HCS). A total of 309 blood samples from individuals in different risk groups were assessed by at least two of the methods mentioned above. Leukocytes were recovered either after centrifugation in Leucosep tubes containing 1.080 Ficoll for pp65 assay or after simple differential lysis steps for DNA detection. HCS was based on DNA hybridization with a CMV RNA probe and its capture by antibodies to DNA-RNA hybrids. The CMV pp65 lower matrix protein was detected by fluorescence with c10-c11 monoclonal antibody in formalin-fixed leukocytes. Concordant results were observed for 92.9, 78.3, and 82.7% of the patients when comparing (i) viral culture and the pp65 antigenemia assay, (ii) viral culture and HCS, and (iii) the pp65 antigenemia assay and HCS, respectively. Discordant results were observed between a positive HCS result and negative culture and/or pp65 results. These results were associated with relatively low DNA levels (< 20 pg/10(6) cells) and positive viruria. In conclusion, the pp65 antigenemia assay is a rapid and reliable method of detecting CMV and is preferable to culture, but the Murex HCS appears to be more sensitive for CMV detection.

Hemodynamic effects of terlipressin and octreotide administration alone or in combination in portal hypertensive rats.

BACKGROUND/AIMS: The action sites and kinetic effects of octreotide and terlipressin may be different. Therefore, we studied the hemodynamic effects of acute administration of these drugs alone or in combination in rats with portal hypertension due to portal vein ligation. METHODS: In a first study performed in anesthetized rats, hemodynamics were measured before and after drug administration (placebo, octreotide: 8 microg x kg(-1) x h(-1) for 30 min, terlipressin: 50 microg/kg bolus, terlipressin + octreotide at the same doses). The second study, performed in conscious rats, included the same groups and drug doses; hemodynamics were measured every 10 min for 1 h. The third study tested the effect of preinfusion of octreotide on responsiveness to terlipressin. RESULTS: Terlipressin produced more marked systemic effects than octreotide by decreasing heart rate and cardiac output and increasing mean arterial pressure. Terlipressin produced a greater decrease in portal pressure than octreotide: placebo: -3+/-5%, terlipressin: -42+/-8%, octreotide: -16+/-10%, combination: -44+/-8% (conscious rats at 20 min, p<10(-4)). The decrease in portal pressure was immediate and lasted at least 60 min with both drugs. Octreotide significantly decreased spleno-renal shunt blood flow (% variation): placebo: -6+/-8, terlipressin: -15.5+/-20, octreotide: -22.5+/-20, combination: -27+/-10 (p<10(-2)). Octreotide preinfusion significantly increased the responsiveness of arterial pressure and heart rate to terlipressin. CONCLUSIONS: Terlipressin decreases portal pressure significantly more than octreotide, while only octreotide significantly decreases collateral blood flow. Simultaneous administration of these drugs does not have significant additive effects but has complementary effects. The preadministration of octreotide alters systemic response to terlipressin.

Long-term administration of PGE1 increases liver fibrosis and collateral blood flow in bile-duct-ligated rats.

BACKGROUND/AIMS: The aim of this study was to assess the effect of early and chronic administration of a prostaglandin E1 analogue (misoprostol) in the prevention of liver fibrosis and portal hypertension. METHODS: Liver fibrosis was induced by bile duct ligation. Controls had a sham operation. Bile-duct-ligated rats were divided into two groups: placebo (vehicle only) and misoprostol (10 microg/d by gavage) for 4 weeks after surgery. Liver fibrosis was assessed by the area of fibrosis (image analysis), liver hydroxyproline content and serum hyaluronate. Systemic and splanchnic hemodynamics were evaluated including spleno-renal shunt blood flow by the transit-time ultrasound technique. RESULTS: Mean arterial pressure was significantly lower in the misoprostol group (p<0.01). There was an unexpected increase in fibrosis parameters in the misoprostol group compared to the placebo group, e.g. area of fibrosis: 9.5+/-4.0 vs 15.0+/-8.1% (p<0.05). Spleno-renal shunt blood flow was significantly higher in the misoprostol group than in the placebo group (4.6+/-3.7 vs 2.2+/-2.0 ml/min, p<0.05) while portal pressure was unchanged. CONCLUSIONS: The early and chronic administration of misoprostol enhances porto-collateral circulation blood flow and the development of liver fibrosis in bile-duct-ligated rats.

Effects of long-term administration of interferon alpha in two models of liver fibrosis in rats.

BACKGROUND/AIMS: The aim of this study was to assess the effect of the early and chronic administration of interferon alpha in the prevention of hepatic fibrosis and portal hypertension. METHODS: Rats with liver fibrosis due to bile duct ligation or CCl4 were divided into three groups: sham, placebo and interferon alpha2a 100,000 UI/day. Liver fibrosis was assessed by the area of fibrosis (image analysis), liver hydroxyproline and mRNA (fibronectin, procollagen alpha2(I)) contents, and serum hyaluronate. Systemic and splanchnic hemodynamics were also evaluated. RESULTS: Interferon alpha significantly decreased fibrosis in the CCl4 model only: area of fibrosis: 13.9+/-3.7 vs 10.5+/-3.3% (p<0.05), hydroxyproline: 1.8+/-0.6 vs 1.2+/-0.2 mg/g wet liver (p<0.001), respectively placebo vs interferon alpha. There was a significant correlation between the area of fibrosis and hydroxyproline liver content (r=0.77 in the biliary model and r=0.87 in the CCl4 model, p<0.0001). Interferon decreased spleno-renal shunt blood flow (2.0+/-1.8 vs 0.9+/-0.7 ml/min; p<0.05) but not portal pressure in the CCl4 model. No significant effects were observed in rats with biliary fibrosis. CONCLUSIONS: The early and chronic administration of interferon alpha prevents the development of liver fibrosis and porto-collateral circulation in the CCl4 model but not in the biliary model. However, the antifibrotic effects of interferon need to be confirmed in further studies.

Spleno-renal shunt blood flow is an accurate index of collateral circulation in different models of portal hypertension and after pharmacological changes in rats.

BACKGROUND/AIMS: Recently, we developed a new method to measure collateral blood flow in rats: splenorenal shunt (SRS) blood flow (BF). The aims were to evaluate the reproducibility of SRSBF measurement in different models of portal hypertension, and to investigate the ability of SRSBF to disclose pharmacological changes. METHODS: Hemodynamics were determined in anesthetized rats with secondary biliary, CCl4 or DMNA cirrhosis and portal vein ligation (PVL) under baseline and pharmacological (octreotide, vapreotide) conditions. The main measurements performed were: SRSBF by the transit time ultrasound (TTU) method and % portosystemic shunts (PSS) by the microsphere method. RESULTS: SRSBF was 6 to 10 times higher in portal hypertensive rats and was similar in the different models of cirrhosis but was higher in portal vein ligated rats than in cirrhotic rats (1.1+/-0.7 vs 0.6+/-0.7 ml x min(-1) x 100 g(-1), p=0.01). SRSBF was correlated with mesenteric %PSS (r=0.61, p<0.01), splenic %PSS (r=0.54, p<0.05), portal pressure (r= 0.32, p<0.05) and the area of liver fibrosis (r=0.33, p<0.05). Octreotide significantly decreased SRSBF (-23+/-20%, p<0.01 vs placebo: -6+/-8%, NS). Vapreotide significantly decreased SRSBF but not mesenteric or splenic %PSS compared to placebo. The variations in SRSBF (-26+/-32%) and in splenic %PSS (0+/-15%) with vapreotide were significantly different (p<0.05) and not correlated (r=-0.1, NS). CONCLUSIONS: Determination of SRSBF by TTU is an accurate way to measure collateral blood flow in different models of intra- and extra-hepatic portal hypertension in rats. Its sensitivity provides accurate measurement of pharmacological changes, unlike the traditional estimation of %PSS by the microsphere method.

Splenorenal shunt blood flow by transit-time ultrasound as an index of collateral circulation in portal hypertensive rats.

The aim of this study was to develop a technique that could serve as an index of portosystemic shunt (PSS) blood flow in portal hypertensive rats whose main shunt is the splenorenal shunt (SRS). The main hemodynamic measurements performed were: SRS blood flow by the transit-time ultrasound (TTU) method, percentage of PSS, and regional blood flows by the microsphere method. We determined the accuracy and reproducibility of SRS blood flow measurements under baseline and pharmacological (octreotide) conditions. SRS blood flow was compared with other hemodynamic characteristics. Two models of portal hypertension were used: secondary biliary and dimethylnitrosamine cirrhosis. The SRS blood flow was correlated with mesenteric (r = .76; P < .001) and splenic (r = .67; P < .01) PSS percentages. The intra- and interobserver agreements for SRS blood flow were excellent: ric = .99 and ric = .98, respectively. SRS blood flow was six times higher in portal hypertensive rats (0.6 +/- 0.7 mL . min-1 . 100 g-1) than in sham rats (0.1 +/- 0.1 mL . min-1 . 100 g-1 [P < .01]). Octreotide significantly decreased SRS blood flow but not mesenteric or splenic PSS percentages. SRS is the main PSS in rats. The measurement of SRS blood flow by TTU is accurate and reproducible. This method can be used to identify new mechanisms in hemodynamic studies that differ from those identified by the measurement of the percentage of PSS by the microsphere method, especially in pharmacological studies.

Antifibrotic and hemodynamic effects of the early and chronic administration of octreotide in two models of liver fibrosis in rats.

The aim of this study was to assess the effect of the early and chronic administration of octreotide in the prevention of hepatic fibrosis and portal hypertension (PHT). Two experimental models of liver fibrosis caused by bile duct ligation (BDL) or CCl4 were divided into 4 rat groups: sham, placebo, and octreotide (10 and 100 micrograms/kg twice daily, subcutaneously). Liver fibrosis was assessed by the area of fibrosis (image analysis), liver hydroxyproline and fibronectin mRNA contents, and serum hyaluronate. Systemic and splanchnic hemodynamic changes were also evaluated, including the splenorenal shunt blood flow by the transit-time ultrasound (TTU) technique. In both models, splenorenal shunt blood flow was significantly lower in the octreotide groups than in the placebo group (P <.05), while portal pressure was not significantly decreased. There was a significant decrease in fibrosis by octreotide in the CCl4 model only: area of fibrosis: 13.9% +/- 3.7% vs. 9.8% +/- 2.5% (P <.01), hydroxyproline: 1.8 +/- 0.6 vs. 1.3 +/- 0.4 mg/g wet liver (P <.05), respectively, placebo vs. octreotide 10 micrograms/kg. There was a significant correlation between the area of fibrosis and hydroxyproline liver content (r =.87 in the biliary model and r =.91 in the CCl4 model; P <.0001). The early and chronic administration of octreotide prevents the development of portocollateral blood flow without reducing portal pressure in two models of liver fibrosis and the development of liver fibrosis in the CCl4 model.

Relationship between vascular reactivity in vitro and blood flows in rats with cirrhosis.

In cirrhosis there is a hyperdynamic circulation, which occurs mainly in the systemic and splanchnic regions. Using isolated-vessel models, previous studies have shown reduced aortic reactivity to vasoconstrictors in rats with cirrhosis. The aim of the present study was to evaluate and compare the vascular responsiveness to phenylephrine in arterial rings and the blood flows from different regions in rats with cirrhosis and controls. Reactivity was studied in isolated thoracic aortic, superior mesenteric arterial and carotid arterial rings from sham-operated and bile-duct-ligated rats by measuring the cumulative concentration-dependent tension induced by phenylephrine (10(-9)-10(-4) M). Blood flows were measured by the radioactive microsphere method. In rats with cirrhosis, a significant hyporeactivity to phenylephrine was observed in both the aorta and the superior mesenteric artery compared with the corresponding arteries of normal rats. This hyporesponsiveness was corrected by N(omega)-nitro-L-arginine (0.1 mM). In contrast, carotid artery reactivity and the responses to N(omega)-nitro-L-arginine were similar in the cirrhotic and control groups. In each case, cardiac output and mesenteric arterial blood flow were significantly higher in cirrhotic than in normal rats. Cerebral blood flows were not significantly different between the two groups. In cirrhotic rats, arterial hyporeactivity may be a consequence of increased regional blood flow and increased production of nitric oxide.