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 In rats with a hypotensive haemorrhage, 4.5 ml of blood was withdrawn and 50% of the withdrawn blood was reinfused before the administration of glypressin or aminoguanidine.3.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.

Alterations of the PPP2R1B gene in human lung and colon cancer

The PPP2R1B gene, which encodes the beta isoform of the A subunit of the serine/threonine protein phosphatase 2A (PP2A), was identified as a putative human tumor suppressor gene. Sequencing of the PPP2R1B gene, located on human chromosome 11q22-24, revealed somatic alterations in 15% (5 out of 33) of primary lung tumors, 6% (4 out of 70) of lung tumor-derived cell lines, and 15% (2 out of 13) of primary colon tumors. One deletion mutation generated a truncated PP2A-Abeta protein that was unable to bind to the catalytic subunit of the PP2A holoenzyme. The PP2R1B gene product may suppress tumor development through its role in cell cycle regulation and cellular growth control.

Development of Bacillus thuringiensis fermentation and process control from a practical perspective

Bacillus thuringiensis (Bt) is the most widely used biopesticide producer in the biological control market. It is very critical for the Bt pesticide industry to be able to achieve a high yield in the Bt fermentation process in order to reduce its cost and compete with chemical pesticides in the market. We review the overall development of Bt fermentation process research and provide our point of view for the future research opportunities and potential improvements. This minireview covers the areas of fermentation physiology, growth dynamics and high-yield process control. It is pointed out that many studies aimed to improve spore count and process research focusing on toxin protein yield is lacking. In addition, significant development opportunities reside in the process development for the genetically engineered Bt strains expressing multiple toxin proteins.

HBV core promoter mutations prevail in patients with hepatocellular carcinoma from Guangxi, China

The development of primary liver cancer frequently is associated with persistent HBV infection, and tumours may arise in individuals who are anti-HBe positive. However, it is unclear whether viruses with an HBeAg-negative phenotype are associated with tumour development or are selected, during seroconversion, after chromosomal integration of wild-type viral DNA. In order to investigate the temporal evolution of the HBV genome in such individuals, the polymerase chain reaction was used to amplify HBV DNA from tumour tissue and serum of 14 patients from Guangxi, China with hepatocellular carcinoma. Comparison of nucleotide and amino acid sequences of the precore and proximal core region of HBV from the two sites in each patient produced evidence of divergence following integration in the tumour, but in most cases, HBeAg-negativity could not be explained by precore mutations. Sequences from the core promoter region were therefore examined and mutations were found in the majority, which are believed to upregulate transcription of the core (and pregenomic) RNA but to downregulate precore mRNA. To determine whether this finding merely reflected sequence variation among geographical isolates of HBV, the same region of HBV DNA from asymptomatic controls was sequenced and these mutations were found to be rare. We hypothesise that HBV with the core promoter mutations replicates at higher levels than the wild type, with the consequence that more integrations occur into the hepatocyte chromosomes during the early stages of infection. These hepatocytes may expand clonally and be targets for further mutagenic events leading to tumour development.

Transcriptional and posttranscriptional control of tyrosine hydroxylase gene expression during persistent stimulation of pituitary adenylate cyclase-activating polypeptide receptors on PC12 cells: regulation by protein kinase A-dependent and protein kinase A-independent pathways

Pituitary adenylate cyclase-activating polypeptide (PACAP) stimulates catecholamine release and biosynthesis in sympathetic postganglionic cells. Moreover, PACAP receptor activation in cultured adrenal chromaffin and superior cervical ganglion cells has been reported to increase the expression of the gene coding for tyrosine hydroxylase (TH), the rate-limiting enzyme in catecholamine biosynthesis. However, the relative contribution of transcriptional and posttranscriptional mechanisms to the effects of PACAP on TH gene expression has not been evaluated. Therefore, in this study we compared the temporal effects of PACAP on TH gene transcription with the duration of its effects on TH mRNA levels. We had previously shown that vasoactive intestinal polypeptide, peptide histidine isoleucine, and secretin, peptides closely related to PACAP, induce TH gene expression through a cyclic AMP (cAMP)-dependent pathway. Therefore, using a mutant PC12 cell line deficient in cAMP-dependent protein kinase II (PKA), we also evaluated the role of the cAMP pathway in the effect of PACAP on TH gene expression. Continuous treatment of wild-type PC12 cells with PACAP (1 nM) increased TH mRNA levels maximally by 12 h and maintained TH mRNA at near maximal levels for at least 2 days. In contrast, the rate of TH gene transcription, as measured by a nuclear run-on assay, was maximal by 1 h and returned to basal levels by 3 h. The fact that a new steady-state level of TH mRNA was achieved and maintained for days in the absence of a sustained increase in TH gene transcription supports the involvement of posttranscriptional mechanisms. Removal of PACAP after 12 h, a time at which TH gene transcription was at basal levels, resulted in a subsequent return of TH mRNA to unstimulated levels within 36 h. Thus, continuous PACAP stimulation is required to maintain sustained increases in TH mRNA levels in the absence of a sustained elevation of transcription. To examine the role of the cAMP pathway in these effects, we compared the effects of PACAP in wild-type PC12 cells and in a mutant PC12 cell line (A126-1B2) that is deficient in PKA. PACAP failed to stimulate either TH mRNA levels or TH gene transcription in the mutant cells. In contrast to the effects of PACAP, dexamethasone increased TH mRNA levels by the same magnitude in both cell lines. It is noteworthy that stimulation of the PKA-deficient mutant cells with a combination of PACAP and dexamethasone (1 microM) produced a synergistic increase in TH mRNA levels, which was nearly twice that induced by dexamethasone stimulation alone. This synergistic effect was not transcriptionally mediated. The effect of the combined treatment on TH gene transcription was identical to the effect of dexamethasone alone. Taken together, these data indicate that PACAP regulates TH gene expression through a transcriptional mechanism requiring an intact cAMP pathway and through posttranscriptional mechanisms under the control of a cAMP-independent pathway(s).

Phase II and pharmacokinetic study of paclitaxel therapy for unresectable hepatocellular carcinoma patients

Hepatocellular carcinoma (HCC) is a common lethal disease in Asia and there is no effective chemotherapy. Identification of new effective drugs in the treatment of inoperable HCC is urgently need. This is a phase II clinical study to investigate the efficacy, toxicity and pharmacokinetics of paclitaxel in HCC patients. Twenty patients with measurable, unresectable HCC, normal serum bilirubin, normal bone marrow and renal functions were studied. Paclitaxel 175 mg m(-2) was given intravenously over 3 h every 3 weeks. No complete or partial responses were observed. Five patients had stable disease. Major treatment toxicities (grade 3-4) were neutropenia (25%), thrombocytopenia (15%), infection (10%) and allergy (10%). Treatment-related deaths occurred in two patients. The median survival was 12 weeks (range 1-36). Paclitaxel is metabolized by the liver and the pharmacokinetics of paclitaxel in cancer patients with liver involvement or impairment may be important clinically. Pharmacokinetic study was completed in 13 HCC patients. The paclitaxel area under the curve was significantly increased (P < 0.02), clearance decreased (P < 0.02) and treatment-related deaths increased (P = 0.03) in patients with hepatic impairment. In conclusion, paclitaxel in this dose and schedule has no significant anti-cancer effect in HCC patients. Paclitaxel should be used with caution in cancer patients with liver impairment.

Recurrent spontaneous bacterial empyema in cirrhosis: a case report

Spontaneous bacterial empyema occurs in about 0.4% of cirrhotic patients, but recurrent attack has rarely been reported. Herein we report a case of repeat episodes of spontaneous bacterial empyema. The patient presented with fever, shortness of breath and three episodes of spontaneous bacterial empyema (accompanied by septic shock in two episodes) within six months. Chest roentgenography showed massive right-side pleural effusion. Thoracentesis yielded pleural effusion containing a neutrophil count of more than 500/microliter. A blood culture grew non-O1 Vibrio cholerae in one episode and the pleural effusion culture grew Aeromonas hydrophila. A chest-tube was inserted during the latest episode due to a low pH and glucose concentration in the pleural fluid. The patient recovered well after medical treatment. The etiology, diagnosis and management of spontaneous bacterial empyema are discussed.

Oxidative stress: an important phenomenon with pathogenetic significance in the progression of acute pancreatitis

BACKGROUND

Reactive oxygen species and related oxidative damage have been implicated in the initiation of acute pancreatitis. Changes in these parameters during disease progression merit further investigation.

AIMS

To evaluate changes and the clinical relevance of superoxide radicals, endogenous antioxidants, and lipid peroxidation during the course of acute pancreatitis.

PATIENTS AND METHODS

Superoxide radicals (measured as lucigenin amplified chemiluminescence), ascorbic acid, dehydroascorbic acid, alpha tocopherol, and lipid peroxidation (measured as thiobarbiturate reactive substances) were analysed in blood samples from 56 healthy subjects, 30 patients with mild acute pancreatitis, and 23 patients with severe acute pancreatitis. The association with grades of disease severity was analysed. Measurements were repeated one and two weeks after onset of pancreatitis.

RESULTS

In the blood from patients with acute pancreatitis, there were increased levels of the superoxide radical as well as lipid peroxides. There was notable depletion of ascorbic acid and an increased fraction of dehydroascorbic acid. Changes in alpha tocopherol were not great except in one case with poor prognosis. Differences between severe and mild acute pancreatitis were significant (p < 0.01). Variable but significant correlations with disease severity scores were found for most of these markers. The normalisation of these indexes postdated clinical recovery one or two weeks after onset of disease.

CONCLUSIONS

Heightened oxidative stress appears early in the course of acute pancreatitis and lasts longer than the clinical manifestations. The dependence of disease severity on the imbalance between oxidants and natural defences suggests that oxidative stress may have a pivotal role in the progression of pancreatitis and may provide a target for treatment.

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.

Extracorporeal membrane oxygenation support for single lung transplantation in a patient with primary pulmonary hypertension

Left single lung transplantation was performed under perioperative extracorporeal membrane oxygenation (ECMO) support for a patient of primary pulmonary hypertension. Continuous ECMO in this patient for one day after the transplantation decreased the pulmonary blood flow and probably served to minimize the potential complication of reperfusion edema of the graft. During this period, the ECMO was gradually weaned so that the grafted lung could adapt itself to the gradually increased blood flow through it. The patient was extubated without difficulty 2 days alter the removal of ECMO and made a smooth recovery.

Severe colonic complications in acute pancreatitis

BACKGROUND

Colonic complications in patients with acute pancreatitis may be very severe and have rarely been analyzed in Chinese patients.

METHODS

We retrospectively evaluated 1,637 patients with acute pancreatitis who were admitted to the Veterans General Hospital-Taipei from January 1986 to December 1995 in order to identify those with severe colonic complications. The clinical, radiologic and pathologic features and surgical findings in these patients are reviewed.

RESULTS

Eight of 1,637 patients with acute pancreatitis had severe colonic complications. Six of them were diagnosed between two and eight weeks after the onset of clinical pancreatitis. All had a Ranson's score of at least 3. Four patients, including one with hematochezia, had a strong positive reaction for occult blood in stool specimens. Computed tomography (CT) revealed necrotizing pancreatitis and colonic wall swelling in all eight patients. Colonic involvement was discovered by CT in two patients prior to surgery, one with colocutancous fistula and the other with colonic perforation. The other six patients were found to have colonic involvement incidentally at the time of laparotomy. All of the colonic involvements were located near the splenic flexure. In addition to necrosectomy, three patients underwent segmental hemicolectomy and the remaining five patients had simple closure of the perforation. Diverting loop ileostomy or colostomy was also carried out in all patients. Three patients (34%) died of overwhelming sepsis superimposed on the subsequent multiple organ failure between 44 and 122 days after the onset of pancreatitis.

CONCLUSIONS

Severe colonic complications of acute pancreatitis are rare. Although preoperative diagnosis is difficult, CT may be helpful to make an early diagnosis. These complications should be suspected in patients with severe acute pancreatitis when acute lower gastrointestinal hemorrhage or positive stool occult blood is found two to eight weeks after the onset of pancreatitis or when CT reveals necrotizing pancreatitis and colonic wall swelling; this will allow early surgical intervention.

Two novel antifibrotics, HOE 077 and Safironil, modulate stellate cell activation in rat liver injury: differential effects in males and females

The perisinusoidal stellate cells of the liver in an injury milieu undergo activation, acquiring a myofibroblast-like phenotype. In this state, they are the principal source of collagen and related proteins in fibrosis. The present studies evaluate the mechanism of action of two novel antifibrotic compounds, HOE 077 and Safironil, which were designed as competitive inhibitors of collagen protein synthesis. Fibrosis was induced in rats by administration of carbon tetrachloride, and activation was monitored as the level of collagen I mRNA or smooth muscle alpha-actin. Both male and female rats were studied. Stellate cell activation, rather than collagen synthesis, proved to be the target of both HOE 077 and Safironil in the intact liver. In culture, the drugs not only prevented the activation of stellate cells but also accelerated their deactivation. They were no more effective in co-cultures containing hepatocytes than in pure stellate cell cultures, indicating that metabolic conversion of HOE 077 was not required. Interestingly, the response of cells from females was greater than that of male cells, leading to the conclusion that stellate activation is sexually dimorphic. This finding may be relevant to the observation that fibrosis in chronic viral hepatitis progresses less rapidly and that hepatocellular carcinoma is less frequent in females than in males.

Effects of high dose octreotide on retrograde bile salt-induced pancreatitis in rats

The effects of somatostatin and octreotide (a long acting somatostatin analogue) in acute pancreatitis are inconclusive. This study examined the prophylactic and therapeutic effects of different doses of octreotide on retrograde sodium taurodeoxycholate-induced acute necrotizing pancreatitis in rats. The rats were divided into 4 groups receiving subcutaneous injection of saline, octreotide 10 microg/kg, 20 microg/kg at 0, 8 and 16 h and octreotide 20 microg/kg at 5, 13 and 21 h, separately. The serum levels of amylase and lipase, pancreatic histopathology, mortality and hemodynamics were examined. Octreotide significantly reduced serum levels of amylase and lipase at 12 h and the degree of pancreatic edema, necrosis and hemorrhage at 18-24 h as compared to the control group. Prophylactic octreotide 10 microg/kg significantly decreased the 24-h mortality from 100% to 44.4% (p < 0.05). The 24-h mortality further reduced to 12.5% and 10% with prophylactic and therapeutic octreotide 20 microg/kg, respectively. The decrease of mean arterial pressure at 12 h was significantly lower in octreotide groups than in the control group. We conclude that octreotide improves pancreatic histopathology and survival in acute necrotizing pancreatitis in rats.

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.

Bladder cancer and drinking water: a population-based case-control study in Washington County, Maryland (United States)

A population-based case-control study was conducted in Washington County, Maryland (United States) to explore the association between incident bladder cancer and exposure to drinking water from chlorinated surface sources. Cancer cases were White residents, enumerated in a 1975 county census and reported to the Washington County Cancer Registry (n = 294) between 1975 and 1992. White controls, frequency matched by age (+/- 5 years) and gender, were selected randomly from the census (n = 2,326). Households receiving municipal water, which generally derived from chlorinated surface waters, were treated as having 'high exposure' and all others, as 'low exposure.' Duration of exposure to type of drinking water was based on length of residence in the census household prior to 1975. Odds ratios (OR) were calculated using logistic regression methods, adjusting for age, gender, tobacco use, and urbanicity. Bladder cancer risk was associated weakly in the general population with duration of exposure to municipal water. The association was limited to those who had smoked cigarettes. In ever-smokers compared with never-smokers with low exposure, the adjusted ORs for bladder cancer risk with increasing exposure were 1.3, 1.4, 1.4, 1.7, 2.2, 2.8, respectively, for 0, 1-10, 11-20, 21-30, 31-40, > 40 years' exposure duration. The ORs in smokers were not diminished after adjusting for smoking history and intensity.

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.

Chemical two-photon uncaging: a novel approach to mapping glutamate receptors

Functional mapping of neurotransmitter receptors requires rapid and localized application of transmitter. The usefulness of caged glutamate for this purpose has been limited, because photolysis by unfocused light above and below the target cell limits depth resolution. This problem is eliminated by using a double-caged glutamate that requires absorption of two photons for conversion to active glutamate, resulting in a substantial improvement in spatial resolution over conventional caged glutamate. This method was used to map the distribution of glutamate receptors on hippocampal pyramidal neurons. A higher density of AMPA receptors was found on distal apical dendrites than on basal or primary apical dendrites, suggesting that synaptic efficacy is locally heterogeneous. Such "chemical two-photon uncaging" offers a simple, general, and economical strategy for spatially localized photolysis of caged compounds.

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.

Synthesis and cytotoxic evaluation of substituted sulfonyl-N-hydroxyguanidine derivatives as potential antitumor agents

A series of sulfonyl-N-hydroxyguanidine derivatives was designed and synthesized for cytotoxic evaluation as potential anticancer agents on the basis of the lead compound LY-181984. Replacement of the ureido moiety of the lead compound with hydroxyguanidine provided a stable cytotoxic agent. The conformation of sulfonyl-N-hydroxyguanidine derivatives, such as N-(4-chlorophenyl)-N'-[(benzo[2,1,3]thiadiazol-4-yl)sulfonyl]-N"- hydroxyguanidine (4g), investigated utilizing HMBC NMR, theoretical calculations, and X-ray crystallography, indicated stacking of the two aromatic rings. The derivatives were evaluated for in vitro cytoxicity against five human tumor cell lines, including HepG2, TSGH 8302, COLO 205, KB, and MOLT-4. The cytotoxic activities of the derived compounds against the human tumor cell lines were equal to or greater than that of the lead compound. N-(4-Chlorophenyl)-N'-[[3,5-dichloro-4-(4-nitrophenoxy)phenyl]sulfonyl]- N"- hydroxyguanidine (4n) and N-(4-chlorophenyl)-N'-[[3,5-dichloro-4-(2-chloro-4-nitrophenoxy)phenyl] sulfonyl]-N"-hydroxyguanidine (4o) exhibited the greatest growth inhibition of solid tumor cell lines. Compound 4o was found to possess antitumor activity against murine K1735/M2 melanoma xenografts.

Tobacco smoking and cancer: the promise of molecular epidemiology

Neoplastic development is a multistage process that includes multiple genetic changes. In this article the authors review studies on molecular epidemiology of tobacco. Current concepts of the multistage carcinogenic model are reviewed, as are their use in observational studies. Finally, benzo[a]pyrene are analyzed as an example.