Effects of prostacyclin inhibition on splanchnic hyposensitivity to glypressin in a hemorrhage-transfused rat model of portal hypertension

BACKGROUND

Hyposensitivity to vasopressin is a well-documented phenomenon in animals with portal hypertension and patients with cirrhosis and hemorrhage. Similar findings exist with infusion of glypressin (a long-acting vasopressin analogue), and this phenomenon could be ameliorated by inhibition of nitric oxide (NO) synthase. Besides NO, excessive formation of prostacyclin (PGI2) has been shown to play an important role in the development of hyperdynamic circulation and the mediation of hyporeactivity to vasoconstrictors in portal-hypertensive states. This study was designed to investigate whether the blockade of PGI2 activity by indomethacin infusion could enhance the portal-hypotensive effect of glypressin in portal-hypertensive rats with bleeding.

METHODS

Portal hypertension was induced by partial portal vein ligation (PVL). Fourteen days after operation systemic and portal hemodynamics were measured in stable or bleeding PVL rats receiving intravenous glypressin (0.07 mg/kg) or indomethacin (5 mg/kg) followed by glypressin infusion. In rats with a hypotensive hemorrhage 4.5 ml of blood was withdrawn, and 50% of the withdrawn blood was reinfused before the administration of glypressin or indomethacin.

RESULTS

Splanchnic hyposensitivity to glypressin was shown in hemorrhage-transfused PVL rats. Indomethacin infusion did not cause significant systemic and portal-hemodynamic changes in bleeding PVL rats (P > 0.05). The addition of indomethacin significantly enhanced the portal-hypotensive effects of glypressin and potentiated the increases in mean arterial pressure induced by glypressin infusion in bleeding PVL rats.

CONCLUSIONS

The improvement of splanchnic hyposensitivity to glypressin in a hemorrhage-transfused rat model of portal hypertension by the administration of indomethacin suggests that PGI2 has in the development of this hyposensitivity.

Establishment of an animal model of hepatic encephalopathy

BACKGROUND

Hepatic encephalopathy is a neuropsychiatric syndrome associated with acute liver failure, chronic parenchymal liver disease or portal systemic anastomosis. The spectrum of symptoms may vary from subtle mental changes to a disrupted circadian rhythm to hepatic coma. In order to investigate the possible pathogenetic mediators and the use of potential new therapies, the aim of our study was to create a reliable animal model for research on hepatic encephalopathy.

METHODS

Forty male Sprague-Dawley rats were used. Fulminant hepatic failure was induced by intraperitoneal injection of thioacetamide (TAA, 350 mg/kg) for three consecutive days (n = 30). Rats treated with normal saline served as controls (n = 10). The clinical stage of hepatic encephalopathy in TAA-treated rats was graded according to neurobehavioral testing. Spontaneous motor activities of rats were calculated using the Opto-Varimex animal activity meter. We also investigated the relationships between the neurobehavioral score and the motor activity count.

RESULTS

Compared with normal, saline-treated rats, those receiving consecutive injections of TAA had apparently lower neurobehavioral scores (p < 0.001) accompanied by significantly blunted motor activities (p < 0.001). A significant correlation was demonstrated between the neurobehavioral score and total movements in rats with encephalopathy (r = 0.71, p < 0.001). In addition, the neurobehavioral score also correlated well with ambulatory movements (r = 0.73, p < 0.001) and vertical movements (r = 0.45, p < 0.05).

CONCLUSIONS

The rat model is acceptable for the study of hepatic encephalopathy, as established in this study. This experimental model can be used to explore the pathogenesis and management of hepatic encephalopathy.

Treatment of mastalgia with tamoxifen in male patients with liver cirrhosis: a randomized crossover study

OBJECTIVE

Mastalgia is occasionally found in patients with liver cirrhosis, especially in those receiving spironolactone for treatment of ascites. The pathogenesis is still unclear. Estrogen excess in cirrhotic patients and estrogenic effects of the spironolactone are possible leading causes. Treatment directed against the preponderance of estrogenic stimulation in these patients has never been investigated. This study was designed to investigate the efficacy and safety of tamoxifen, an estrogen antagonist, on mastalgia in patients with liver cirrhosis.

METHODS

A total of 16 male cirrhotic patients with mastalgia were randomly assigned to two groups. One group was treated with tamoxifen (20 mg p.o., b.i.d.) for 1 month, followed by placebo for the next month. The other group was treated in the reverse order. All patients received spironolactone for ascites and/or peripheral edema, and the drug was continued during the study period. The size of the breasts and the degree of breast pain and tenderness were recorded in all subjects before and after the treatment periods. Serum levels of estradiol and testosterone were measured using the radioimmunoassay method.

RESULTS

Of the 16 patients, 14 experienced a decrease or disappearance of the breast pain and/or tenderness during the tamoxifen treatment period, whereas only two of the 16 patients felt an improvement during the placebo period (p < 0.05). There were significant improvements in the breast pain and tenderness scores and decreases in the breast sizes during the tamoxifen treatment period (before vs after: 1.4+/-0.3 vs 0.4+/-0.2, p = 0.002; 1.9+/-0.2 vs 0.5+/-0.2, p < 0.001; and 6.8+/-0.6 vs 5.5+/-0.6 cm, p = 0.02, respectively), whereas no obvious change was seen during the placebo period. Serum levels of estradiol and testosterone did not change significantly after the tamoxifen or placebo treatments (p > 0.05). No major side effects were noted during the therapeutic periods.

CONCLUSIONS

Tamoxifen is effective and safe in the management of mastalgia in male cirrhotic patients taking spironolactone.

Splanchnic endotoxin levels in cirrhotic rats induced by carbon tetrachloride

BACKGROUND

Bacterial translocation (passage of intestinal bacteria to mesenteric lymph nodes) observed in cirrhosis may be a source of endotoxin that can stimulate nitric oxide production and participate in the pathogenesis of hyperdynamic circulation. Currently, there are no published data concerning splanchnic endotoxin levels in cirrhotic rats. This study was designed to determine systemic and portal hemodynamics and to detect endotoxins in the portal and systemic circulation.

METHODS

Liver cirrhosis was induced by carbon tetrachloride intragastric gavage. Systemic and splanchnic endotoxin levels in control rats and cirrhotic rats with or without ascites were measured using a chromogenic Limulus assay. In addition, systemic and portal hemodynamic data were obtained using a thermodilution technique and catheterization.

RESULTS

Cirrhotic rats with ascites had the lowest systemic vascular resistance (2.6 +/- 0.1 mmHg.ml-1.min.100 g body weight, BW) compared with control rats (6.3 +/- 0.3 mmHg.ml-1.min.100 g BW; p < 0.05) and cirrhotic rats without ascites (3.7 +/- 0.3 mmHg.ml-1.min.100 g BW; p < 0.05). Cirrhotic rats with ascites displayed the highest splanchnic levels of endotoxin (10.6 +/- 3.1 pg/ml) compared with cirrhotic rats without ascites (2.0 +/- 0.7 pg/ml; p < 0.05) and control rats (2.0 +/- 0.4 pg/ml; p < 0.05). There was no difference in the splanchnic endotoxin levels between control rats and cirrhotic rats without ascites (p > 0.05). Similar results were observed with systemic endotoxin values (cirrhotic rats with ascites, 10.8 +/- 2.8 pg/ml; cirrhotic rats without ascites, 2.7 +/- 0.6 pg/ml; control rats, 2.5 +/- 0.4 pg/ml; p < 0.05). A significant correlation existed between portal and systemic endotoxin values in cirrhotic rats with or without ascites (r = 0.96, p < 0.001 and r = 0.9, p < 0.05, respectively), whereas this correlation did not exist in control rats (r = 0.5, p > 0.05).

CONCLUSIONS

Cirrhotic rats with ascites had the lowest systemic vascular resistance and the highest splanchnic endotoxin levels when compared with cirrhotic rats without ascites and control rats. These results suggest that splanchnic endotoxemia may be involved in the development and/or maintenance of hyperdynamic circulation.

Motor skills training enhances lesion-induced structural plasticity in the motor cortex of adult rats

To assess behavioral experience effects on synaptic plasticity after brain damage, the present study examined the effects of complex motor skills training (the acrobatic task) on synaptic changes in layer V of the motor cortex opposite unilateral damage to the forelimb sensorimotor cortex (FLsmc). Adult male rats were given lesions or sham operations followed by 28 d of training on the acrobatic task [acrobat condition (AC)]. As a motor activity control [motor control (MC)], lesion and sham animals were given simple repetitive exercise. Previously, FLsmc lesions and acrobatic training have independently been found to result in increases in synapse to neuron ratios in the intact motor cortex relative to controls, and both of these effects were replicated in the present study. In addition, acrobat training after lesions significantly increased layer V synapses per neuron relative to sham-AC and lesion-MC rats. Thus, the combination of acrobatic training and lesions resulted in an enhanced synaptogenic response. Synapse subtypes were also differentially affected by the conditions. Lesion-MC and sham-AC primarily had increases in the number of synapses per neuron formed by multiple synaptic boutons in comparison to sham-MC. In contrast, lesion-AC had increases in both multiple and single synapses. Multiple synaptic spines and perforated synapses were also differentially affected by training versus lesions. On tests of coordinated forelimb use, lesion-AC rats performed better than lesion-MC rats. In addition to supporting a link between behavioral experience and structural plasticity after brain damage, these findings suggest that adaptive neural plasticity may be enhanced using behavioral manipulations as "therapy."

Effects of vasopressin on portal-systemic collaterals in portal hypertensive rats: role of nitric oxide and prostaglandin

This study investigated the effect of vasopressin on portal-systemic collaterals in portal hypertensive rats and the influence of nitric oxide (NO) and prostaglandin on the responsiveness of collateral vessels to vasopressin. The vascular responsiveness to graded concentrations of vasopressin was tested with or without the incubation of n(omega)-nitro-L-arginine (NNA) (100 micromol/L) and/or indomethacin (10 micromol/L) in perfused collateral vascular beds of rats with portal hypertension induced by partial portal vein ligation. In addition, concentration-response curves to vasopressin with incubation of a vasopressin V(1) receptor antagonist d(CH(2))(5)Tyr(Me) arginine vasopressin and concentration-response curves to a V(2) receptor agonist 1-desamino-8-D-arginine vasopressin were performed. Vasopressin significantly increased the perfusion pressure of collaterals, and this effect was suppressed by the addition of the V(1) receptor antagonist. Perfusion with the V(2) receptor agonist had no effect on the collaterals. Incubation with NNA, indomethacin, or both significantly potentiated the response of collaterals to vasopressin. In addition, the pressor response to vasopressin in the combination group was significantly higher than that in the NNA-alone group. The results show that vasopressin produces a direct vasoconstrictive effect on the portal-systemic collaterals of portal hypertensive rats. This effect is mediated by the vasopressin V(1,) but not V(2), receptors. The attenuation of the response to vasopressin by NO and prostaglandin suggest a function role of both mediators in the regulation of the portal-systemic collateral circulation in portal hypertensive rats.

Evidence against a role for endotoxin in the hyperdynamic circulation of rats with prehepatic portal hypertension

BACKGROUND/AIMS

Excessive formation of nitric oxide may mediate the generalized vasorelaxation and hyporesponsiveness to vasoconstrictors observed in portal hypertensive states. Endotoxin, released from the bowel and detoxified by the liver, could stimulate inducible nitric oxide synthase directly or indirectly via the cytokine cascade. This study investigated the effect of chronic intraperitoneal injection of polymyxin B, a neutralizing antagonist of endotoxin, on the hemodynamics of partially portal vein-ligated (PVL) rats.

METHODS

Concomitantly with endotoxin (600 EU) and dactinomycin (80 microg), polymyxin B (0.1 mg) or normal saline (N/S) was administered via an intraperitoneal route to male Sprague-Dawley rats. Twenty-four hours later, mean arterial pressure was determined. In PVL rats polymyxin B (0.1 mg in 5 cc N/S) or N/S was given intraperitoneally twice daily from 2 days prior to operation until 5 days (short-term) or 14 days (long-term) after the operation. Long-term polymyxin B- or N/S-treated sham-operated rats were included as controls. Hemodynamic studies with a thermodilution technique were performed at the end of treatment. Blood samples were collected from another series of PVL rats with long-term treatment to determine plasma levels of endotoxin and tumor necrosis factor-alpha. Plasma levels of endotoxin and tumor necrosis factor-alpha were measured by Limulus assay and the ELISA method, respectively.

RESULTS

With the dosage of 0.1 mg polymyxin B, hypotension in rats subjected to endotoxin and dactinomycin administration could be corrected (polymyxin B vs. placebo: 130.0+/-7.7 vs. 108.8+/-6.7 mm Hg, p<0.05). However, long-term or short-term treatment with the same dosage of polymyxin B failed to ameliorate the hyperdynamic circulation of PVL rats. In addition, long-term treatment with polymyxin B did not change systemic and portal hemodynamics in sham-operated rats. Plasma levels of endotoxin and tumor necrosis factor-alpha were comparable in PVL rats treated with long-term polymyxin B or N/S (p>0.05).

CONCLUSIONS

Our findings do not support the role of endotoxin in the hyperdynamic circulation of PVL rats.

Spider angiomas in patients with liver cirrhosis: role of alcoholism and impaired liver function

BACKGROUND

Spider angioma is a common sign in patients with liver cirrhosis, but the pathogenesis is still unclear. Alcohol and hyperestrogenemia are both possible etiologies. This study was designed to investigate the relationship of spider angiomas in patients with liver cirrhosis to alcohol, liver function test results, and plasma levels of sex hormones.

METHODS

Eighty-two patients with liver cirrhosis and 18 healthy subjects were enrolled in this study. The number, size, and location of the spider angiomas were recorded for all subjects. Plasma levels of estradiol and testosterone were measured.

RESULTS

Cirrhotic patients had significantly higher estradiol/testosterone ratios (26.8 +/- 5.1 x 10(-3) versus 8.8 +/- 2.0 x 10(-3); P = 0.002) than healthy controls. Twenty-seven (33%) of the 82 cirrhotic patients had spider angiomas. Cirrhotic patients with spider angiomas were younger (56 +/- 3 versus 66 +/- 1 years; P = 0.002) and had higher serum bilirubin levels (3.3 +/- 0.6 versus 1.7 +/- 0.2 mg/dl; P = 0.002), longer prothrombin time (16.8 +/- 0.8 versus 14.8 +/- 0.4 sec; P = 0.01), and higher prevalence of alcoholism (41% versus 20%; P = 0.04) than those without. Stepwise logistic regression showed that alcoholism and serum bilirubin level were the only significant and independent predictors associated with the presence of spider angiomas in cirrhotic patients (odds ratio = 3.5; 95% confidence interval = 1.2-10.8; P = 0.03, and odds ratio = 2.8; 95% confidence interval = 1.3-5.7; P = 0.006, respectively).

CONCLUSIONS

Alcoholism and impaired liver function are important predictors of the presence of spider angiomas in patients with liver cirrhosis.

Plasma concentrations of interferon-alpha in patients with liver cirrhosis: relationship to systemic and portal hemodynamics

BACKGROUND

Nitric oxide (NO) plays an important role in the pathogenesis of the hyperdynamic circulation observed in portal hypertensive states. Interferon (IFN)-alpha can stimulate NO formation directly or indirectly via cytokines. However, IFN-alpha concentrations seem to increase or decrease in cirrhotic patients. This study investigated the plasma concentration of IFN-alpha in patients with cirrhosis and its relationship to systemic and portal hemodynamics.

METHODS

Thirty-six patients with cirrhosis and 47 healthy controls had blood samples taken for the determination of plasma concentrations of IFN-alpha by enzyme-linked immunosorbent assay. Systemic and portal hemodynamics were measured in patients with cirrhosis on the same day of blood sampling using Swan-Ganz catheterization and the thermodilution technique.

RESULTS

As compared with healthy subjects, patients with cirrhosis demonstrated a significantly higher IFN-alpha detectable rate (> 3 pg/ml, 14.9% vs 36.1%, p < 0.05). In cirrhotic patients, the IFN-alpha detectable rates were similar between those with and without decompensation, a hepatic venous pressure gradient greater than 12 mmHg, or the presence of large esophageal varices (p > 0.05). There was no significant difference in the systemic vascular resistance or hepatic venous pressure gradient between cirrhotic patients with and without a detectable plasma IFN-alpha concentration.

CONCLUSIONS

Plasma IFN-alpha concentrations tended to increase in patients with cirrhosis. However, IFN-alpha concentrations do not play a role in the hyperdynamic circulation observed in patients with cirrhosis.

p53 gene mutations and rearrangements in non-Hodgkin's lymphoma

BACKGROUND

Alterations of the p53 gene have been associated with the progression of certain human malignancies. To establish further the correlation between p53 gene alterations and progression of non-Hodgkin's lymphomas (NHLs), the authors analyzed both mutations and rearrangements of the p53 gene in a cohort of 84 NHLs.

METHODS

Eighty-four NHLs were analyzed for p53 gene alterations. Point mutations of exons 5-9 were studied by polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP), and DNA rearrangements were studied by Southern blot analysis. RESULTS. Point mutations and DNA rearrangements of the p53 gene were detected in 6 (7.2%) and 3 (3.6%) patients, respectively. All p53 gene abnormalities were found exclusively in B-cell NHLs. Taken together, patients with p53 gene alterations had poorer survival than other patients (P = 0.024). However, of the three patients with p53 gene rearrangements, the two who appeared to have one normal allele showed a relatively better response to chemotherapy and had longer survival (27 and 47 months). In contrast, the remaining patient who had rearranged bands much stronger than the germline, and thus appeared to have both alleles rearranged, was refractory to chemotherapy and had poorer survival (6 months).

CONCLUSIONS

Patients with NHLs of intermediate and high grades who carried point mutations or rearrangements of p53 genes had worse outcomes than other patients. Patients with one abnormal p53 allele and one residual normal allele had a more favorable prognosis than those with two abnormal alleles.

Role of substance P in the pathogenesis of spider angiomas in patients with nonalcoholic liver cirrhosis

OBJECTIVE

Cutaneous spider angioma is a common sign observed in patients with liver cirrhosis, but its pathogenesis is still unclear. Increased plasma levels of estrogen, vascular dilation, and neovascularization are possible etiologies. This study was designed to investigate the relationship of spider angiomas in patients with nonalcoholic liver cirrhosis to the plasma levels of sex hormones and various vasodilators and hemodynamic parameters.

METHODS

A total of 60 patients with nonalcoholic liver cirrhosis and 20 healthy subjects were included in this study. The number, size, and location of the spider angiomas were recorded. Plasma levels of estradiol, testosterone, substance P, calcitonin gene-related peptide, and nitrate/nitrite and forearm hemodynamics were measured.

RESULTS

Cirrhotic patients showed higher plasma estradiol/testosterone ratios (28.3+/-47.2 x 10(-3), median 10.5 x 10(-3) vs 8.2+/-8.3 x 10(-3), median 5.7 x 10(-3), p = 0.003) and levels of nitrate/ nitrite (29.9+/-17.5, median 23.8 vs 21.4+/-10.0, median 20.6 micromol/L, p = 0.01) and substance P (47.5+/-62.5, median 29.2 vs 15.2+/-7.7, median 12.3 pg/ml, p < 0.001) than healthy controls. Sixteen (27%) of the 60 cirrhotic patients had spider angiomas. Cirrhotic patients with spider angiomas disclosed higher plasma levels of substance P (84.7+/-105.3, median 53.1 vs 34.5+/-30.7, median 25.8 pg/ml, p = 0.006) and serum levels of bilirubin (3.9+/-3.8, median 1.9 vs 1.9+/-1.9, median 1.2 mg/dl, p = 0.02) than those without. Stepwise logistic regression showed substance P was the only significant and independent predictor associated with the presence of spider angiomas in cirrhotic patients (odds ratio = 3.0, 95% confidence interval = 1.4-6.6, p = 0.01).

CONCLUSION

Plasma levels of substance P are elevated in patients with nonalcoholic cirrhosis and may play an important role in the pathogenesis of spider angiomas.

Aminoguanidine ameliorates splanchnic hyposensitivity to glypressin in a haemorrhage-transfused rat model of portal hypertension

1. Hyposensitivity to vasopressin is a well-documented phenomenon in animals with portal hypertension and patients with cirrhosis subjected to haemorrhage. Excessive formation of nitric oxide is at least partly responsible for the vascular hyporesponsiveness to vasoconstrictors observed in experimental portal hypertension or in rats with haemorrhagic shock. This study investigated whether addition of aminoguanidine, a preferential inducible nitric oxide synthase inhibitor, to glypressin (a long-acting vasopressin analogue) could enhance its portal hypotensive effect in portal-hypertensive rats with bleeding.2. Portal hypertension was induced by partial portal vein ligation. Fourteen days after operation, systemic and portal haemodynamics were measured in stable or bleeding portal vein-ligated rats receiving intravenous glypressin (0.07 mg/kg) or aminoguanidine (70 mg/kg) followed by glypressin infusion. In rats with a hypotensive haemorrhage, 4.5 ml of blood was withdrawn and 50% of the withdrawn blood was reinfused before the administration of glypressin or aminoguanidine.3. Glypressin resulted in a significantly greater decrease in portal pressure in portal vein-ligated rats without bleeding than in those with bleeding (P<0.001). In contrast, glypressin induced similar changes in mean arterial pressure between the two groups (P>0.05). The addition of aminoguanidine significantly potentiated the portal-hypotensive effect of glypressin in bleeding portal vein-ligated rats (P<0.005) without an effect on the changes in mean arterial pressure induced by glypressin infusion (P>0.05).4. Splanchnic hyposensitivity to glypressin exists in a haemorrhage-transfused rat model of portal hypertension. This hyposensitivity can be ameliorated by the administration of aminoguanidine.

Chronic administration of octreotide ameliorates portal hypertension and portal hypertensive gastropathy in rats with cirrhosis

1. Portal hypertension and hyperdynamic circulation have been postulated to play a role in the pathogenesis of portal hypertensive gastropathy. Administration of octreotide to portal hypertensive rats has been shown to reduce portal pressure and ameliorate hyperdynamic circulation. 2. This study investigated the effects of chronic administration of octreotide on systemic and portal haemodynamics and the development of portal hypertensive gastropathy in carbon tetrachloride-induced cirrhotic rats. 3. After 12 weeks of carbon tetrachloride induction, cirrhotic rats were randomly assigned to receive either placebo (5% dextrose in water) or octreotide (65 micrograms/kg in 5% dextrose in water) subcutaneously twice daily for 10 days. Haemodynamic studies with a thermodilution technique and gastric morphometric analyses were performed at 10 days after treatment. 4. In cirrhotic rats, octreotide treatment induced a significant increase in systemic vascular resistance (2.7 +/- 0.2 versus 3.4 +/- 0.2 mmHg/ml.min-1.100 g-1, P < 0.05) and decrease in portal pressure (12.5 +/- 1.2 versus 9.9 +/- 0.5 mmHg, P < 0.05) compared with placebo-treated rats. In addition, octreotide treatment significantly reduced the mean cross-sectional area of gastric mucosal vessels (2290 +/- 145 versus 1810 +/- 101 micron 2, P < 0.05). 5. This study shows that chronic octreotide treatment ameliorates the development of portal hypertensive gastropathy in cirrhotic rats. The effect of octreotide on portal hypertensive gastropathy may, at least partly, be due to the alleviation of portal hypertension and hyperdynamic circulation.

Plasma substance P levels in patients with liver cirrhosis: relationship to systemic and portal hemodynamics

OBJECTIVES

Nitric oxide has been proposed as being responsible for the hyperdynamic circulation observed in portal hypertensive states. Substance P, a neuropeptide partly cleared by liver, induces vasodilation through the activation of the endothelial nitric oxide pathway. This study investigated the plasma levels of substance P in cirrhotic patients and the relationship of these levels to systemic and portal hemodynamics.

METHODS

Sixty-four patients with cirrhosis and 53 healthy controls had blood samples taken for determining plasma values of substance P by ELISA. Systemic and portal hemodynamics were measured on the same day of blood sampling using a Swan-Ganz catheterization and thermodilution technique.

RESULTS

Plasma levels of substance P were higher in cirrhotic patients than in healthy controls (45.7 +/- 2.0 vs 32.9 +/- 1.0 pg/ml, p < 0.001) and directly correlated with Child-Pugh's score (r = 0.52, p < 0.0001). Compared with compensated cirrhotic patients, decompensated cirrhotic patients had higher plasma levels of substance P accompanied by a lower systemic vascular resistance and higher hepatic venous pressure gradient. There was no significant correlation between plasma levels of substance P and systemic vascular resistance and hepatic venous pressure gradient. In addition, no significant difference in plasma levels of substance P was observed between cirrhotic patients with and cirrhotic patients without a hepatic venous pressure gradient > 12 mm Hg or between patients with and patients without large esophageal varices.

CONCLUSIONS

Plasma levels of substance P are increased in patients with cirrhosis and may contribute to the pathogenesis and/or maintenance of hyperdynamic circulation in decompensated patients. The severity of cirrhosis is more important than portal hypertension and the severity of esophageal varices for the development of increased plasma substance P levels.

Prognostic value of plasma endotoxin levels in patients with cirrhosis

BACKGROUND

Endotoxemia has frequently been observed in patients with cirrhosis. Previous studies have shown that cirrhotic patients with endotoxemia have a higher mortality than those without. We evaluated the clinical value of plasma endotoxin level in predicting short-term (3 months) and long-term (2 years) survival among cirrhotic patients and compared it with the Child-Pugh score.

METHODS

Plasma endotoxin levels were determined in 102 cirrhotic patients without clinical evidence of infection by a quantitative Limulus assay. The patients were followed up for 3 months to assess short-term survival and for 2 years for long-term survival.

RESULTS

Plasma endotoxin levels increased progressively as liver function deteriorated. In short-term survival analysis, plasma endotoxin levels were significantly higher in non-survivors than those in survivors (10.6 +/- 2.2 pg/ml versus 5.8 +/- 0.5 pg/ml; P < 0.05). Both plasma endotoxin and serum bilirubin levels, but not the Child-Pugh score, were significant factors in predicting short-term survival in multivariate analysis. In long-term survival analysis, plasma endotoxin levels did not differ significantly between survivors and non-survivors (6.1 +/- 0.6 pg/ml versus 7.3 +/- 1.1 pg/ml; P > 0.05) and was not an independent predictor of long-term survival. In contrast, both Child-Pugh score and serum bilirubin levels were significant predictors of long-term survival in multivariate analysis.

CONCLUSIONS

In patients with cirrhosis, plasma endotoxin levels progressively increase as liver function deteriorates and may be useful in predicting short-term survival.

Hyperdynamic circulation of cirrhotic rats with ascites: role of endotoxin, tumour necrosis factor-alpha and nitric oxide

1. Hyperdynamic circulation observed in portal hypertensive states is characterized by generalized vasodilation, increased cardiac index and increased systemic and regional blood flows. Endotoxin, tumour necrosis factor-alpha (TNF-alpha) and nitric oxide (NO) have been reported to be involved in the pathogenesis of hyperdynamic circulation, but the interactions between endotoxin, TNF-alpha and NO in cirrhotic rats with ascites have never been specifically addressed. 2. This study was designed to determine systemic and portal haemodynamics and plasma levels of endotoxin, TNF-alpha and nitrate/nitrite in cirrhotic rats with ascites and investigate the relationships between these substances. 3. Plasma concentrations of endotoxin, TNF-alpha and nitrate/nitrite (an index of NO production) were determined in 25 cirrhotic rats with ascites and 17 control rats using the Limulus assay, ELISA and a colorimetric assay respectively. In addition, haemodynamic studies were performed in another ten cirrhotic rats with ascites and ten control rats. 4. Cirrhotic rats with ascites had hyperdynamic circulation accompanied by increased plasma levels of endotoxin, TNF-alpha and nitrate/nitrite, as compared with control rats. Significant correlation existed between plasma levels of endotoxin and nitrate/ nitrite (r = 0.59, P < 0.0001) and between plasma levels of endotoxin and TNF-alpha (r = 0.63, P < 0.0001). No correlation was detected between plasma levels of TNF-alpha and nitrate/nitrite (r = 0.24, P > 0.05). 5. This study suggests that endotoxaemia developed in cirrhotic rats with ascites may stimulate NO formation directly or indirectly via cytokine cascade, and consequently participate in the development and/or maintenance of hyperdynamic circulation.

Prolonged bleeding time: a new clinical manifestation of hepatocellular carcinoma?

The association between prolonged bleeding time and hepatocellular carcinoma (HCC) has not been well studied. We investigated whether bleeding time is prolonged in cirrhotic patients with HCC and studied the role of clinical characteristics, tumour size, and laboratory data in predicting bleeding time prolongation. After excluding patients that presented with blood dyscrasia and uraemia, 58 cirrhotic patients with HCC, 106 cirrhotic patients without HCC, and 44 age-and sex-matched healthy subjects were included in the study. Bleeding time, imaging studies, clinical characteristics and biochemical data were obtained for every patient. Cirrhotic patients with and without HCC had longer bleeding times (554 +/- 32 s, respectively) compared with healthy controls (357 +/- 13 s, P < 0.05). Hepatocellular carcinoma patients with a large tumour burden (> 5 cm in diameter) had a significantly longer bleeding time than those patients without (663 +/- 105 vs 376 +/- 23 s, respectively, P < 0.05). After excluding patients with a platelet count < or = 80 000/mm3, cirrhotic patients classified as Child-Pugh's grading A and with a large tumour burden had longer bleeding times(580 +/- 87 s) than patients with a small tumour burden (< or = 5cm in diameter) and cirrhotic patients without HCC (371 +/- 22 and 416 +/- 29 s, respectively, P < 0.05). In cirrhotic patients with HCC, higher serum bilirubin levels, a Child-Pugh's grading C, and a tumour size > 5 cm in diameter were found to be significant predictors for prolonged bleeding time on univariate analysis. On multivariate analysis, both tumour size > 5 cm in diameter and a Child-Pugh's grading C (odd's ratio, 95% confidence interval and P value were measured as 38.5, 2.8-534.7, < 0.001, and 10.5, 0.9-117.6, 0.02, respectively) were the significant independent predictors. A significant correlation existed between tumour diameter and bleeding time (r = 0.44, P < 0.01). In conclusion, these results suggest that prolonged bleeding time may be categorized as a new clinical manifestation in patients with HCC. In addition to cirrhosis, HCC itself may also participate in the pathogenesis of bleeding time prolongation.

Hyperdynamic circulation of cirrhotic rats: role of substance P and its relationship to nitric oxide

BACKGROUND

It has been suggested that excessive formation of nitric oxide (NO) is responsible for the hyperdynamic circulation observed in portal hypertension. Substance P is a neuropeptide partly cleared by the liver and causes vasodilatation through the activation of the endothelial NO pathway. However, there are no previously published data concerning the plasma level of substance P in cirrhotic rats and its relationship to NO.

METHODS

Plasma concentrations of substance P and nitrate/nitrite (an index of NO production) were determined in control rats and cirrhotic rats with or without ascites using an enzyme-linked immununosorbent assay and a colorimetric assay, respectively. In addition, systemic and portal hemodynamics were evaluated by a thermodilution technique and catheterization.

RESULTS

Cirrhotic rats with and without ascites had a lower systemic vascular resistance (2.6 +/- 0.2 and 3.9 +/- 0.4 mmHg ml(-1) x min x 100 g body weight, respectively) and higher portal pressure (14.6 +/- 0.6 and 11.3 +/- 1.8 mmHg) than control rats (6.5 +/- 0.3 mmHg x ml(-1) x min x 100 g BW and 6.8 +/- 0.2 mmHg, respectively, P < 0.05), and cirrhotic rats with ascites had the lowest systemic vascular resistance. Plasma levels of nitrate/nitrite progressively increased in relation to the severity of liver dysfunction (control rats, 2.7 +/- 0.5 nmol/ml; cirrhotic rats without ascites, 5.6 +/- 1.3 nmol/ml; cirrhotic rats with ascites, 8.3 +/- 2.2 nmol/ml; P < 0.05). Cirrhotic rats with ascites displayed higher plasma values of substance P (57.7 +/- 5.9 pg/ml) than cirrhotic rats without ascites (37.9 +/- 3.1 pg/ml, P < 0.05) and control rats (30.1 +/- 1.0 pg/ml, P < 0.05). There was no significant difference in plasma substance P values between control rats and cirrhotic rats without ascites (P > 0.05). No correlation was found between plasma levels of substance P and nitrate/nitrite (r = 0.318, P > 0.05).

CONCLUSIONS

Excessive formation of NO may be responsible, at least partly, for the hemodynamic derangements in cirrhosis. Although substance P may not participate in the initiation of a hyperdynamic circulation in cirrhosis, it may contribute to the maintenance of the hyperdynamic circulation observed in cirrhotic rats with ascites.

Hemodynamic studies and esophageal morphometric analyses in portal hypertensive rats with left adrenal vein ligation

BACKGROUND

Despite many attempts to create esophageal varices in experimental animals, most of them have failed. This study investigated whether rats with partial portal vein ligation (PVL) and left adrenal vein ligation (LAL) develop hyperdynamic circulation and dilated esophageal submucosal veins as compared with sham-operated (Sham) plus LAL rats.

METHODS

Two series of experiments were performed to measure (a) systemic and portal hemodynamics and (b) the cross-sectional area of esophageal submucosal veins in Sham, PVL, Sham plus LAL, and PVL plus LAL rats. Hemodynamic studies with a thermodilution technique and esophageal morphometric analyses were performed 14 days after the operation.

RESULTS

PVL rats with or without LAL had a significantly lower mean arterial pressure and systemic vascular resistance accompanied by a significantly cardiac index and portal pressure than Sham rats with or without LAL (P < 0.05). LAL did not induce changes in mean arterial pressure, cardiac index, systemic vascular resistance, hear rate, or portal pressure in either Sham or PVL rats (P > 0.05). The mean cross-sectional area of esophageal submucosal veins in PVL rats with LAL (7340 +/- 833 microns2) was significantly larger than that in Sham rats with LAL (4236 +/- 556 microns2; P < 0.05). There was no significant difference in the mean cross-sectional area of esophageal submucosal veins between PVL and Sham rats without LAL.

CONCLUSIONS

PVL rats with LAL developed hyperdynamic circulation similar to PVL rats without LAL. In addition, PVL plus LAL rats had larger esophageal submucosal veins than Sham plus LAL rats. This study shows that the esophageal submucosal veins of the 14-day partially portal vein-ligated rats with LAL resemble the structural abnormalities observed in human esophageal varices, suggesting that this model could be useful to investigate this entity.

Hyperdynamic circulation in prehepatic portal hypertension: role of tumor necrosis factor-alpha

BACKGROUND

Portal hypertension is associated with a hyperdynamic circulation characterized by increased cardiac output and reduced systemic vascular resistance. Tumor necrosis factor-alpha (TNF-alpha) is a peptide mediator released by mononuclear cells on activation by endotoxin, tissue injury and malignancy. This cytokine induces vasodilatation by activating nitric oxide synthesis. The aim of this study is to investigate if TNF-alpha is involved in the pathogenesis of hyperdynamic circulation observed in portal vein-ligated (PVL) rats.

METHODS

Systemic and portal hemodynamics were determined in seven PVL and five sham-operated (SHAM) rats using a thermodilution technique. In addition, plasma TNF-alpha concentrations were determined in another 34 PVL and 16 SHAM rats using commercially available enzyme-linked immunosorbent assay.

RESULTS

PVL rats had a significantly lower mean arterial pressure (109 +/- 17 mmHg vs. 133 +/- 12 mmHg, p < 0.001) and systemic vascular resistance (2.5 +/- 0.6 mmHg.ml-1.min.100 g BW vs. 4.6 +/- 0.8 mmHg.ml-1.min.100 g BW, p < 0.001) accompanied by a significantly higher portal pressure (14 +/- 1.9 mmHg vs. 9 +/- 2.1 mmHg, p < 0.001) and cardiac index (47.0 +/- 12.1 ml.min-1.100 g BW-1 vs. 29.3 +/- 3.5 ml.min-1.100 g BW-1, p < 0.001) when compared with SHAM rats. Also, PVL rats had significantly higher plasma levels of TNF-alpha as compared with SHAM rats (13.8 +/- 0.9 pg/ ml vs. 11.1 +/- 0.5 pg/ml, p < 0.05).

CONCLUSIONS

This study suggests that elevated plasma levels of TNF-alpha observed in PVL rats may participate in the development and/or maintenance of the hyperdynamic circulation occurring in prehepatic portal hypertension.

Aminoguanidine corrects hyperdynamic circulation without ameliorating portal hypertension and portal hypertensive gastropathy in anesthetized portal hypertensive rats

BACKGROUND/AIMS

Portal hypertension and hyperdynamic circulation (i.e. generalized vasodilation and increased cardiac output and regional organ blood flows) may play an important role in the development of portal hypertensive gastropathy. This study investigated the effect of chronic administration of aminoguanidine, a selective inducible nitric oxide synthase inhibitor, to portal hypertensive rats on hemodynamics and the development of portal hypertensive gastropathy.

METHODS

Partial portal vein-ligated or sham-operated rats were randomly assigned to receive either placebo (distilled water) or aminoguanidine (approximately 100 mg/kg per day subcutaneously) for 2 days prior to and 14 days. Hemodynamic studies with a thermodilution technique and gastric morphometric analysis were performed at 14 days after the operation.

RESULTS

In rats given placebo, portal vein-ligated rats had a significantly lower mean arterial pressure and systemic vascular resistance associated with a significantly higher cardiac index and portal pressure than sham-operated rats (p<0.05). In portal vein-ligated rats aminoguanidine induced a significant increase in mean arterial pressure and systemic vascular resistance accompanied by a significant decrease in cardiac index (p<0.05) without changes in portal pressure (p>0.05). Despite persistence of portal hypertension, the aminoguanidine-treated portal vein-ligated rats had similar mean arterial pressure, cardiac index, and systemic vascular resistance as seen in placebo-treated sham-operated rats. The mean cross-sectional area of gastric mucosal vessels was significantly higher in placebo-treated portal vein-ligated than in placebo-treated sham-operated rats (p<0.05). Treatment with aminoguanidine did not induce changes in the mean cross-sectional area of gastric mucosal vessels in either portal vein-ligated or sham-operated rats (p>0.05).

CONCLUSIONS

The results show that in portal hypertensive rats long-term aminoguanidine therapy corrects the hyperdynamic circulation without inducing changes in portal pressure and ameliorating the development of portal hypertensive gastropathy. This study suggests that, instead of correcting hyperdynamic circulation, treatment of portal hypertensive gastropathy should be aimed at reducing portal pressure.

Efficiency of cytoplasmic delivery by pH-sensitive liposomes to cells in culture

The intracellular processing of pH-sensitive liposomes composed of cholesterylhemisuccinate (CHEMS) and dioleoylphosphatidylethanolamine (DOPE) by eukaryotic cell lines has been compared to non-pH-sensitive liposomes made of CHEMS and dioleoylphosphatidylcholine (DOPC). The pH-sensitive liposomes can deliver encapsulated fluorescent molecules [calcein, fluoresceinated dextran, fluoresceinated polypeptide, and diphtheria toxin A chain (DTA)] into the cytoplasm. Cytoplasmic delivery can be blocked in the presence of ammonium chloride or EDTA, indicating that the process requires a low-pH environment and the presence of divalent cations. Inhibition of cellular protein synthesis by DTA delivery from the pH-sensitive liposome is orders of magnitude greater than from the non-pH-sensitive liposome composition. The delivery of DTA into the cytoplasm by pH-sensitive liposomes is at least 0.01% of cell-associated liposomal DTA. There is no significant difference in the degradation rate of bovine serum albumin (BSA) or the rate of acidification of pH-sensitive dye, 8-hydroxy-1,3,6-pyrene-trisulfonate (HPTS), when delivered to cells in pH-sensitive and non-pH-sensitive liposomes. Thus the efficiency of cytoplasmic delivery is less than 10% of the cell-associated liposome contents, which is the smallest difference that can be detected by these two assays. Based upon the various assays used to measure liposome content disposition in the cell, we conclude that the efficiency of cytoplasmic delivery by the CHEMS/DOPE liposomes is greater than 0.01% and less than 10% of the cell-associated liposomal contents.

Increased efficacy of phosphonoformate and phosphonoacetate inhibition of herpes simplex virus type 2 replication by encapsulation in liposomes

Phosphonoformate and phosphonoacetate encapsulated in liposomes have substantially greater activity against herpes simplex virus type 2 in Vero cell tissue culture than the nonencapsulated compounds at the same dose. Encapsulation of phosphonoformate in liposomes resulted in a 30-fold increase of the antiviral effect with no increase in cytotoxicity measured by inhibition of thymidine incorporation into normal Vero cells. Thus, the selectivity of the liposomal drug increased 27-fold compared with the nonencapsulated compound. Liposome encapsulation of phosphonoacetate at a ratio of 0.3 mumol/mumol of lipid resulted in a 150-fold increase of antiviral activity with a concomitant 250-fold increase in cytotoxicity. However, the selectivity of phosphonoacetate could be increased by reducing the drug-to-lipid ratio. Liposome uptake by Vero cells, measured by the cell association of a nonexchangeable radiolabeled lipid, plateaued after 24 h of incubation and saturated at 60 nmol of lipid per mg of cellular protein at a lipid concentration of 300 microM. The saturation of liposome uptake on the Vero cells may account for the 27-fold increase in selectivity observed with the liposomal phosphonoformate. The greater activity of the encapsulated phosphono compounds is most likely due to their increased transport into the cytoplasm; this occurs subsequent to the uptake and processing of the liposome in the lysosomes of the cell. Liposome encapsulation of these agents may result in superior efficacy against viral infections residing in endocytotically and phagocytically active cells such as macrophages.

Cytolysis of rat glioma cells in vitro by autonomic drugs

The results of glioma chemotherapy obtained so far have been rather disappointing. New attempts have been made to kill glioma cells with autonomic drugs. Experiments were done with rat C-6 glioma cells in the cell culture. Among all cholinergic blockers tested, only the irreversible cholinergic blockers such as bromoacetylcholine (BrACh), iodoacetylcholine and alphabungarotoxin were effective to inhibit glioma cells (with 50% cytolytic doses of 6.7 x 10(-6)M, 3.0 x 10(-6)M and 7.4 x 10(-5)M respectively). It is interesting to note that the hydrolytic product of BrACh, bromoacetate, was as potent as BrACh to inhibit glioma cells. Most of the adrenergic blockers, both reversible and irreversible ones, showed no cytolytic activity on glioma cells with concentrations up to 1.0 x 10(-4)M except phentolamine and propranolol which showed weak cytolytic activities. It is interesting to note, on the other hand, that 6-hydroxydopamine (an adrenergic neuron degenerating agent) and 5,6-dihydroxytryptamine (a serotonergic neuron degenerating agent) also showed mild cytolytic effects on glioma cells with 50% cytolytic doses of 5.0 x 10(-5)M and 5.3 x 10(-5)M, respectively.