Mechanism of carbon tetrachloride autoprotection: an in vivo study based on 13C-aminopyrine and 13C-galactose breath tests

Therapeutic effects of the oriental herbal medicine Sho-saiko-to on liver cirrhosis and carcinoma

The traditional Chinese herbal medicine Sho-saiko-to is a mixture of seven herbal preparations that has long been used in the treatment of chronic liver disease. Various clinical trials have shown that Sho-saiko-to protects against the development of hepatocellular carcinoma in cirrhotic patients. However, the mechanism by which Sho-saiko-to protects hepatocytes against hepatic fibrosis and carcinoma is not yet known. Basic science studies have demonstrated that Sho-saiko-to reduces hepatocyte necrosis and enhances liver function. Sho-saiko-to significantly inhibits hepatic fibrosis by inhibiting the activation of stellate cells, the major producers of collagen in the liver, as well as by inhibiting hepatic lipid peroxidation, promoting matrix degradation, and suppressing extracellular matrix (ECM) accumulation. Furthermore, clinical trials have shown that Sho-saiko-to lowers the rate of hepatocellular carcinoma (HCC) development in patients with cirrhosis and increases the survival of patients with HCC. Unfortunately, some case reports have shown the side effects of Sho-saiko-to. Most of the side effects were interstitial pneumonia and acute respiratory failure induced by Sho-saiko-to in Japan. As a result of analyzing these case reports, the incidence and risk are increased by co-administration of interferon, duration of medication, and, high in an elderly population. This review discusses the properties of Sho-saiko-to with regards to the treatment of chronic liver diseases and suggests the side effects of Sho-saiko-to.

Systems responses of rats to aflatoxin B1 exposure revealed with metabonomic changes in multiple biological matrices

Exposure to aflatoxins causes liver fibrosis and hepatocellular carcinoma posing a significant health risk for human populations and livestock. To understand the mammalian systems responses to aflatoxin-B1 (AFB1) exposure, we analyzed the AFB1-induced metabonomic changes in multiple biological matrices (plasma, urine, and liver) of rats using (1)H NMR spectroscopy together with clinical biochemistry and histopathologic assessments. We found that AFB1 exposure caused significant elevation of glucose, amino acids, and choline metabolites (choline, phosphocholine, and glycerophosphocholine) in plasma but reduction of plasma lipids. AFB1 also induced elevation of liver lipids, amino acids (tyrosine, histidine, phenylalanine, leucine, isoleucine, and valine), choline, and nucleic acid metabolites (inosine, adenosine, and uridine) together with reduction of hepatic glycogen and glucose. AFB1 further caused decreases in urinary TCA cycle intermediates (2-oxoglutarate and citrate) and elevation of gut microbiota cometabolites (phenylacetylglycine and hippurate). These indicated that AFB1 exposure caused hepatic steatosis accompanied with widespread metabolic changes including lipid and cell membrane metabolisms, protein biosynthesis, glycolysis, TCA cycle, and gut microbiota functions. This implied that AFB1 exposure probably caused oxidative-stress-mediated impairments of mitochondria functions. These findings provide an overview of biochemical consequences of AFB1 exposure and comprehensive insights into the metabolic aspects of AFB1-induced hepatotoxicity in rats.

Methods and functions: Breath tests

Breath tests provide a valuable non-invasive diagnostic strategy to in vivo assess a variety of enzyme activities, organ functions or transport processes. Both the hydrogen breath tests and the (13)C-breath tests using the stable isotope (13)C as tracer are non-radioactive and safe, also in children and pregnancy. Hydrogen breath tests are widely used in clinical practice to explore gastrointestinal disorders. They are applied for diagnosing carbohydrate malassimilation, small intestinal bacterial overgrowth and for measuring the orocecal transit time. (13)C-breath tests non-invasively monitor the metabolisation of a (13)C-labelled substrate. Depending on the choice of the substrate they enable the assessment of gastric bacterial Helicobacter pylori infection, gastric emptying, liver and pancreatic function as well as measurements of many other enzyme activities. The knowledge of potential pitfalls and influencing factors are important for correct interpretation of breath test results before drawing clinical conclusions.

13C-breath tests: current state of the art and future directions

13C-breath tests provide a non-invasive diagnostic method with high patient acceptance. In vivo, human and also bacterial enzyme activities, organ functions and transport processes can be assessed semiquantitatively using breath tests. As the samples can directly be analysed using non-dispersive isotope selective infrared spectrometers or sent to analytical centres by normal mail breath tests can be easily performed also in primary care settings. The 13C-urea breath test which detects a Helicobacter pylori infection of the stomach is the most prominent application of stable isotopes. Determination of gastric emptying using test meals labelled with 13C-octanoic or 13C-acetic acid provide reliable results compared to scintigraphy. The clinical use of 13C-breath tests for the diagnosis of exocrine pancreatic insufficiency is still limited due to expensive substrates and long test periods with many samples. However, the quantification of liver function using hepatically metabolised 13C-substrates is clinically helpful in special indications. The stable isotope technique presents an elegant, non-invasive diagnostic tool promising further options of clinical applications. This review is aimed at providing an overview on the relevant clinical applications of 13C-breath tests.

Honokiol protects against carbon tetrachloride induced liver damage in the rat

This study aims to investigate the possible hepato-protective effects of honokiol against liver damage and cirrhosis induced by carbon tetrachloride (CCl(4)) in the rat. Rats were treated acutely, or chronically with CCl(4) at 5 day intervals (0.06 mL/100 g body weight, administered as 50% vol/vol solution in liquid paraffin) by gavage, in combination with phenobarbitone in drinking water (0.5 g/L for 7 days prior to, and during CCl(4) treatment) to induce liver damage. Some were also co-treated with 0.1 mg/kg or 0.03 mg/kg honokiol (i.p.) or with appropriate vehicle. In vivo measurement of the liver sinusoidal area was performed using confocal microscopy following i.v. fluorescein isothiocyanate (FITC) dextran. Liver histology and function tests were performed, and liver and body weights were measured. Confocal microscopy showed that acute and chronic CCl(4) treatment significantly reduced the sinusoidal area. Honokiol (0.1 mg/kg, but not 0.03 mg/kg) partially reversed the decrease in the sinusoidal area after acute or chronic treatments with CCl(4). Acute and chronic CCl(4) treatment produced significant histological liver damage. Honokiol (0.1 mg/kg) significantly reduced the histological damage caused by chronic treatment. Chronic treatment with CCl(4) caused a significant increase in the bilirubin level that was not observed following the high dose of honokiol (0.1 mg/kg). In conclusion, this study showed that honokiol exhibits potent hepato-protective effects in rats treated with CCl(4).

Effects of Sho-saiko-to extract and its components, Baicalin, baicalein, glycyrrhizin and glycyrrhetic acid, on pharmacokinetic behavior of salicylamide in carbon tetrachloride intoxicated rats

To elucidate the effects of Sho-saiko-to extract and its components, baicalin, baicalein, glycyrrhizin and glycyrrhetic acid, against the effects of longer periods of acute hepatic injury induced by CCl4, we measured serum ALT activity in male Wistar rats for five days after ip administration of CCl4 (0.2 ml/kg), and examined the daily changes of the pharmacokinetic behavior of salicylamide (SAM) for five days. Serum ALT activity rose to a maximum level within a day after administration of CCl4 and then decreased to the control level after three. Sho-saiko-to extract and its components could suppress this acute change in serum ALT activity to less than 50% of CCl4 alone. However, the pharmacokinetics of SAM showed that liver function recovers in a biphasic manner, so that plasma clearance (CL) decreased significantly at days 1 and 3 after administration of CCl4 (P<0.05). We concluded that the CL change at day 1 corresponds to the acute action of CCl4 intoxication, and that the change at day 3 is effect of physiologically reduced liver function due to the liver regeneration for tissue repair after the CCl4 hepatic injury. Sho-saiko-to extract and its components were shown to suppress acute hepatic injury induced by CCl4, and to bring about an early recovery in liver function.

Relationship between thrombopoietin serum levels and liver function in patients with chronic liver disease related to hepatitis C virus infection

OBJECTIVES

Thrombopoietin (Tpo) is an important regulator of megakaryocyte maturation and platelet production, and is mainly produced by the liver. A decrease in Tpo production is partly responsible for the thrombocytopenia observed in patients with chronic liver disease (CLD). The aim of this study was to evaluate the relationship between Tpo serum levels and liver function in patients with CLD related to hepatitis C virus (HCV) infection.

METHODS

We studied 37 patients with various degrees of HCV-related CLD. Of the patients, 17 had chronic hepatitis and 20 liver cirrhosis. Liver function was evaluated in all patients by the following hepatic blood flow dependent and independent tests that explore various hepatic metabolic functions: carbon-13 (13C)-aminopyrine breath test (13C-ABT), 13C-galactose breath test (13C-GBT), and monoethylglycinexylidide (MEGX) test. Liver function tests results were correlated with Tpo serum levels.

RESULTS

Tpo serum levels were significantly lower in patients with liver cirrhosis (88 +/- 23 pg/ml) as compared to those in patients with chronic hepatitis (128 +/- 55 pg/ml, p=0.0031). However, they did not correlate with serum albumin, bilirubin, or prothrombin activity. Tpo serum levels showed a significant positive correlation with 13C-ABT results (hourly dose at 30 min, rs=0.489, p=0.002; cumulative dose at 120 min, rs=0.425, p=0.008). Moreover, they showed a fair, positive correlation with 13C-GBT hourly dose at 30 min (rs=0.366, p=0.028), and a trend toward a positive correlation with the various MEGX test sampling times (MEGX15, rs=0.314, p=0.059; MEGX30, rs=0.284, p=0.088; and MEGX60, rs=0.320, p=0.059).

CONCLUSIONS

In this study we have shown that a progressive decline in liver function in patients with HCV-related CLD is paralleled by a decrease in Tpo production. The different correlations observed between Tpo and the various liver function tests suggests that this finding is mainly the result of a decrease in hepatic functional mass rather than dependent on alteration in splanchnic hemodynamic.

Impairment of cytochrome P-450-dependent liver activity in cirrhotic patients with Helicobacter pylori infection

BACKGROUND

Helicobacter pylori gastric infection has been associated with various digestive and extra-digestive diseases. The systemic influence of gastric H. pylori infection seems to be mediated by the release of various cytokines. In liver disease, bacterial infections have been associated with the impairment of liver metabolic function.

AIMS

To evaluate the influence of H. pylori infection on liver function as assessed by means of the monoethylglycinexylidide test, which depends upon liver blood flow and cytochrome P-450 activity, and the 13C-galactose breath test, which depends on cytosolic enzymatic activity and is correlated with hepatic functional mass. Moreover, to evaluate whether H. pylori-associated modifications of liver function may be related to tumour necrosis factor-alpha serum levels.

PATIENTS AND METHODS

Thirty-five patients with liver cirrhosis of various aetiologies, who underwent monoethylglycinexylidide and 13C-galactose breath tests, were retrospectively evaluated for H. pylori infection by means of anti-H. pylori immunoglobulin G. The main clinical, biochemical and functional characteristics of the patients as well as their tumour necrosis factor-alpha serum levels were then analysed on the basis of the presence of H. pylori infection.

RESULTS

Twenty-one patients tested positive for H. pylori infection (60%), and 11 tested negative (31.4%). No clinical or biochemical differences were observed between H. pylori-infected and non-infected patients. H. pylori infection showed no difference in distribution according to Child-Pugh classes (A, 55%; B and C, 67%). The monoethylglycinexylidide test results were significantly lower at each sampling time in H. pylori-positive patients compared to H. pylori-negative patients (MEGX15, P=0.027; MEGX30, P=0.014; MEGX60, P=0.028), while 13C-galactose breath test showed no significant differences considering both cumulative percentage dose and percentage dose/h. The median tumour necrosis factor-alpha serum levels were no different between H. pylori-positive (16.1 pg/mL, 95% confidence interval, 8.7-28.7) and H. pylori-negative (12.3 pg/mL, 95% confidence interval, 8.7-23.4) patients.

CONCLUSIONS

In cirrhotic patients, H. pylori infection seems to selectively affect cytochrome P-450 liver activity, while hepatic functional mass does not seem to be impaired. Tumour necrosis factor-alpha does not seem to be the mediator of this impairment. Further studies are needed to evaluate the impact of H. pylori eradication on parameters of liver function.

13C breath tests: visions and realities

Breath tests have been used in research laboratories for over 25 y. Originally, the tests were based on the use of (14)C, rather than on the nonradioactive isotope, (13)C. When (13)C became widely available at a reasonable cost, research groups in the United States and Europe developed methodologies to measure (13)C abundance in samples of CO(2). The tests used a variety of substrates and measured pancreatic function, fat absorption, bacterial overgrowth and P(450) mixed-function oxidase. Thus far, the only test to be approved by the Food and Drug Administration is the (13)C-urea breath test. This manuscript describes the process by which approval is gained, and indicates the steps necessary for other tests to receive Food and Drug Administration approval.

[1-(13)C] breath test of galactose and fructose for quantitative liver function

BACKGROUND

Using a rat model of hepatectomy, we investigated whether the severity of hepatopathy could be quantitatively measured from changes in expiratory (13)CO(2) levels after intravenous administration of [1-(13)C]fructose or [1-(13)C]galactose.

MATERIALS AND METHODS

Under nembutal anesthesia, 100 mg/kg of [1-(13)C]fructose or [1-(13)C]galactose was administered to rats via the femoral vein, and expiratory (13)CO(2) levels were measured for 120 min. Then, 30, 70, or 90% hepatectomy was performed. In the control group, simple laparotomy was performed. A breath test was conducted 20 min after laparotomy. We examined the correlation of a single point (13)CO(2) level (SP) every 5 min until 30 min, and at 45 and 60 min with liver wt/body wt (LW/BW) (%).

RESULTS

In the control group and all groups undergoing hepatectomy, the [1-(13)C]fructose breath test graph reached a plateau level at about 25 min. In the control group, the [1-(13)C]galactose breath test graph reached a plateau level, but in all groups undergoing hepatectomy a plateau level was not reached during measurement. The correlation coefficient between SP(5) after [1-(13)C]fructose administration and LW/BW was the highest, 0.656 (P = 0.0017). The correlation coefficient between SP(25) after [1-(13)C]galactose administration and LW/BW was the highest, 0.923 (P < 0.0001).

CONCLUSION

In the breath test with intravenously administered [1-(13)C]fructose, hepatopathy could not be quantitatively evaluated accurately. However, hepatopathy could be quantitatively evaluated accurately by measuring SP(25) in the breath test with intravenously administered [1-(13)C]galactose over a short period.

[13C]-Galactose breath test: correlation with liver fibrosis in chronic hepatitis C

BACKGROUND

The galactose elimination capacity test is a quantitative liver function test that has been shown to be a potential surrogate marker for death in advanced chronic liver diseases. However, this test lacks sensitivity in early liver disease. The goal of this study was to evaluate a [13C]-galactose breath test (GBT) in a population of patients with chronic hepatitis C.

DESIGN

The GBT was performed in 10 control subjects and 50 patients with chronic hepatitis C; the results were compared with the METAVIR pathological scoring of liver biopsy specimens and with standard biochemical liver function tests.

RESULTS

In 10 patients, oral vs. intravenous administration of galactose yielded similar results for the GBT (3.01% +/- 0.12% dose h-1 for oral galactose vs. 2.98 +/- 0.21 for intravenous). The GBT was then performed orally in the remaining 40 patients and 10 control subjects. A significant difference was observed between control subjects and patients (4.51% +/- 0.18% vs. 2.97% +/- 0.14% dose h-1, P < 0.0001). A significant difference for GBT results was observed between each fibrosis stage, but not with regard to the activity score.

CONCLUSIONS

The GBT results are dependent on the severity of liver fibrosis in chronic hepatitis C. Further studies are needed to evaluate the usefulness of the GBT for the follow-up of chronic hepatitis C.

Continuous monitoring of 13C-aminopyrine metabolism in rats: effects of cold exposure and noradrenaline

A system was developed to allow constant monitoring of hepatic cytochrome P450 activity in awake and unrestrained rats. A continuous 13C-aminopyrine perfusion was performed, and breath samples obtained for endogenous CO2 production and 13C measurements, to calculate 13C O2 production due to aminopyrine demthylation. Increasing doses of 13C-aminopyrine produced a hyperbolic increase of expired 13CO2, compatible with an in vivo measurement of enzymatic activity. Acute-cold exposure of the rats during 13C-aminopyrine perfusion produced a two-fold increase of endogenous CO2 production, together with a 27% increased 13C-aminopyrine metabolism (p<0.05 vs basal conditions). In contrast, noradrenaline (20 microg/kg BW/min), despite a similar effect on energy expenditure, did not significantly change 13C-aminopyrine metabolism. Acute-cold exposure is known to stimulate both adrenal catecholamine secretion and the sympathetic nervous system. The observed difference in 13C-aminopyrine demthylation during cold exposure and nonadrenaline perfusion, therefore, could be due to a more specific effect of adrenal catecholamines on liver aminopyrine metabolism. These results suggest the possibility of prolonged in vivo monitoring of liver metabolism pathways such as aminopyrine demethylation, thus allowing the study of drug acute interactions with cytochrome P450 system.