A mutant rat strain is described with autosomal recessive conjugated hyperbilirubinemia. Transport of conjugated bilirubin and tetrabromosulfophthalein from liver to bile is severely impaired whereas uptake of organic anions from plasma to liver is normal. During the first 10 days of life, serum bilirubin levels are 147 +/- 11 mumoles per liter with 68.7% diconjugates and 27.9% monoconjugates. In adult rats, serum bilirubin is 33 +/- 8 mumoles per liter with 81.8% diconjugates and 12.1% monoconjugates vs. 0.3 +/- 0.1 mumole per liter unconjugated bilirubin in normal adult rats. Bile acid metabolism is only mildly affected. In young rats, serum bile acid levels are normal. In adult rats, bile acid levels are elevated to 49 +/- 11 mumoles per liter vs. 10 +/- 6 mumoles per liter in normal rats. The bile flow in mutant rats is reduced to about 50%. This might be caused by a reduction of the bile acid-independent bile fraction. Liver marker enzyme activities in mutant rat serum are normal. Liver morphology is also normal. Total urinary coproporphyrin excretion is not elevated but urinary coproporphyrin isomer I excretion is increased, a pattern like that in Dubin-Johnson syndrome in humans. However, unlike Dubin-Johnson syndrome, the mutant rats do not have the characteristic black hepatic pigment. These rats provide a unique model to study mechanisms of bile formation and cholestasis.

Animals↗

PubMedDate not supplied

Selective hepatobiliary transport defect for organic anions and neutral steroids in mutant rats with hereditary-conjugated hyperbilirubinemia.

Mutant rats (TM rats) with abnormal hepatic excretory function were used to study biliary transport of dibromosulfophthalein, ouabain, tributylmethyl ammonium, cholate and taurocholate. In whole animals, dibromosulfophthalein and ouabain clearance is reduced to 7 and 37% of normal, respectively, due to severely impaired excretion from liver to bile. Initial uptake rates of these agents are relatively little affected. In the isolated perfused liver preparation, dibromosulfophthalein is retained within liver and perfusion medium, and the 60-min recovery on bile is reduced to 1.5 vs 75% in normal controls. Biliary excretion of cholate, taurocholate and the quaternary ammonium cation, [14C]tributylmethyl ammonium, is not impaired. These results provide evidence for a selective defect of organic anion and neutral steroid transport in TM rats and confirm that multiple pathways exist for the hepatobiliary excretion of organic anions, neutral steroids, bile acids and cations. Bile flow in whole animals and in the isolated perfused liver is reduced to 50 and 30% of normal, respectively. This suggests that a normal function of the excretory systems for organic anions and neutral steroids is important for the maintenance of normal bile flow.

Animals↗

PubMedDate not supplied

Protein carbonyls in decidua and placenta of pre-eclamptic women as markers for oxidative stress.

Enhanced levels of reactive oxygen species (ROS) and decreased levels of antioxidants may contribute to the development of pre-eclampsia. Protein carbonyls may be sensitive biomarkers for ROS-mediated protein damage, whereas the ferric reducing ability of plasma (FRAP) value may serve as marker for antioxidant capacity.Twenty-two healthy pregnant women and 50 patients with severe pre-eclampsia, 25 of whom with concurrent (haemolysis, elevated liver enzymes, low platelets) HELLP syndrome were investigated prospectively with respect to placental and decidual levels of protein carbonyls and FRAP antioxidant capacity. Measurements were evaluated using the Kruskal-Wallis or Mann-Whitney U -tests for comparison between groups, and the Wilcoxon signed-rank test for comparison within groups. Spearman's correlation tests were used for correlation analyses. Placental and decidual protein carbonyl levels were higher in pre-eclampsia with HELLP than in healthy pregnancy, whereas FRAP levels were lower. Differences between pre-eclampsia and healthy pregnancy showed the same trend, but did not reach statistical significance. In pre-eclampsia with HELLP syndrome carbonyl levels as well as FRAP levels were significantly higher in placenta as compared with decidua.Higher levels of protein carbonyls and lower antioxidant capacity in both placenta and decidua in pre-eclampsia with concurrent HELLP syndrome as compared to healthy pregnancy may indicate that considerable ROS-mediated damage occurs in this disorder.

Adult↗

PubMedDate not supplied

Effects of dietary anticarcinogens on rat gastrointestinal glutathione peroxidase activity.

Several naturally occurring and synthetic food components reduce gastrointestinal cancer. Many of these compounds are scavengers of free radicals, formed during oxidative stress. Glutathione peroxidases (GPxs) protect against free radicals by catalysing their inactivation, thereby consuming glutathione (GSH). This might be one of the mechanisms leading to cancer prevention. We studied the effect of several dietary anticarcinogens on gastrointestinal GPx enzyme activities in male Wistar rats. Total as well as selenium-dependent and non-selenium-dependent GPx (t-GPx, Se-GPx and nSe-GPx) enzyme activities were determined in cytosolic fractions of oesophagus, gastric and colonic mucosa and liver. d-Limonene induced all three types of GPx activities in the oesophagus. d-Limonene and PEITC induced colonic t-GPX and nSe-GPx activity. beta-Carotene induced all three colonic GPx activities and hepatic t-GPx and Se-GPx activity. Coumarin and alpha-tocopherol induced gastric t-GPx and colonic nSe-GPx activity. Oltipraz enhanced oesophageal and gastric t-GPx and oesophageal, gastric and colonic Se-GPx. All other anticarcinogens induced one type of GPx activity at one site. In conclusion, the specific enhancement of GPx enzyme activities by dietary anticarcinogens might lead to a more efficient reduction of organic hydroperoxides and hydrogen peroxide and thus add to prevention of carcinogenesis in these organs.

Animals↗

PubMedDate not supplied

Correlation between iododeoxyuridine and MIB-1 labelling index in gastric carcinoma and adjacent normal gastric tissue.

BACKGROUND: In vivo labelling with synthetic thymidine analogues, such as Iododeoxyuridine (IdU) and Bromodeoxyuridine (BrdU), has frequently been used to estimate tumour proliferation. However, this method requires intravenous administration of IdU or BrdU, thymidine analogues that are potential mutagens. Recently, the monoclonal antibody MIB-1 has been developed, recognizing the Ki-67 nuclear antigen, which is associated with cell cycle proliferation and is found throughout the cell cycle (G1, S, G2 and M phases), but not in resting (G0) cells. We studied the correlation between the MIB-1 labelling index (LI) and the IdU labelling index in normal and malignant gastric tissue. PATIENTS AND METHODS: Twenty patients with gastric cancer received an intravenous injection of IdU (200 mg/m2) before surgery. Specimens were obtained from gastric carcinoma and adjacent normal gastric tissue. The samples were fixed in formalin and immunohistochemical analyses of IdU LI and MIB-1 LI were performed. The LI was defined as the percentage of labelled nuclei of 5000 nuclei counted. RESULTS: The IdU LI ranged from 3.3% to 18.2% in gastric carcinoma and from 0.5% to 5.6% in adjacent normal gastric mucosa, whereas the MIB-1 LI ranged from 4.2% to 46.0% in gastric cancer and from 1.3% to 25.1% in adjacent normal gastric mucosa. Comparison of IdU LI with MIB-1 LI, using the Spearman rank correlation coefficient test showed a significant correlation between IdU LI and MIB-1 LI in normal gastric tissue (r = 0.63, p < 0.05). However, in gastric carcinoma no significant correlation was found between either proliferation marker (r = 0.07, N.S.). CONCLUSION: MIB-1 accurately reflects the in vivo IdU LI in normal gastric tissue, whilst in gastric carcinoma the MIB-1 LI does not seem to be a substitute for the in vivo IdU LI.

Aged↗

PubMedDate not supplied

Glutathione S-transferases and iododeoxyuridine labelling index during chemotherapy of gastric cancer.

BACKGROUND: Resistance to chemotherapeutic agents is a major problem in the treatment of patients with gastric cancer. Many factors may play a role in the resistance to cytotoxic drugs. The purpose of this study was to investigate the significance of glutathione (GSH), glutathione S-transferases (GSTs) and cell proliferation as parameters for response and resistance to chemotherapy in patients with gastric cancer. METHODS: In endoscopic biopsies of normal and malignant gastric tissue from 15 patients with gastric cancer treated by chemotherapy, the GSH content, GST activity and levels of GST Alpha, Mu and Pi isoenzymes were determined before the start of chemotherapy and after 2 and 6 cycles. Furthermore, cell proliferation was determined in these biopsies after in vivo Iododeoxyuridine (IdU) labelling. RESULTS: None of the above mentioned parameters were predictive for response to chemotherapy. After 2 courses of chemotherapy there was an increase of median GSH content (367%) in three patients with partial response (PR), whereas there was a decrease (43%) in five patients with progressive disease (PD) (p < 0.05). Median GST activity increased (257%) in patients with PR and declined (31%) in patients with PD (p < 0.05). GST Pi showed a median increase of 326% in responding patients and a 59% decrease in progressive patients (p < 0.05). There were no significant changes in GST Alpha and Mu. In seven patients with stable disease (SD) there were no significant changes in GSH/GST parameters. CONCLUSION: GSH/GST parameters and IdU labelling index determined before the start of chemotherapy were not predictive for response to that chemotherapy. However, the differences of GSH and GST parameters between responding and progressive patients suggests a role for the GSH/GST system in the susceptibility of gastric tumor cells to chemotherapy.

ATP-Binding Cassette Transporters↗

PubMedDate not supplied

Urinary GSTP1-1 excretion is markedly increased in normotensive pregnancy as well as in preeclampsia.

BACKGROUND: Glutathione S-transferases (GSTs) are present in large amounts in the human kidney, where they demonstrate a specific distribution. The assessment of urinary excretion of GST alpha (proximal tubules) and pi (distal and collecting tubules) could be helpful in determining if, and to what degree renal tubular damage is present in preeclampsia and whether this damage is in the proximal or distal region. METHODS: Urine samples were collected from 22 women with severe preeclampsia and/or HELLP syndrome (PE), from 30 non-pregnant women with a history of severe preeclampsia (HPE), from 18 women with uncomplicated pregnancies (PC) and from 30 non-pregnant women with a history of uncomplicated pregnancies (HPC). GSTA1-1 and GSTP1-1 were assayed by ELISA and were expressed as nanograms per 10 mmol creatinine (Cr). RESULTS: Median urinary GSTP1-1 concentrations were significantly (p<0.001) higher in women with preeclampsia [62.2 (4.3-291.2) ng/10 mmol Cr] compared to non-pregnant women with a history of preeclampsia [22.3 (0-142.6) ng/10 mmol Cr]). In addition, in normotensive pregnant women, urinary GSTP1-1 concentrations were significantly (p<0.01) higher [82.6 (8.3-206.7) ng/10 mmol Cr]) compared to non-pregnant controls [5.1 (0-66.7) ng/10 mmol Cr]. No difference in GSTP1-1 concentrations was found between women with preeclampsia and normotensive pregnant women. GSTA1-1 concentrations were not significantly different between the four groups of women investigated. There were no correlations between the degree of proteinuria and urinary GSTP1-1 or GSTA1-1 concentrations. CONCLUSION: GSTP1-1 metabolism in the distal tubule changes during normotensive as well as preeclamptic pregnancy. Whether this is due to tubular cell damage, disturbed resorption or an increase in cellular levels cannot be determined as yet.

Adult↗

PubMedDate not supplied

Immunohistochemical determination of glutathione S-transferases in gastric carcinomas and in adjacent normal gastric epithelium.

Glutathione S-transferases (GSTs) are a family of isoenzymes that play an important role in protecting cells against cytotoxic and carcinogenic agents. The distribution and levels of GST Alpha and Pi in normal and malignant gastric tissue of 34 patients with gastric cancer were examined immunohistochemically. Expression of GST Alpha and Pi was observed in 47 and 100 percent of the tumors, respectively. In normal mucosa both enzyme classes were present in 100 percent of the specimens. Mucous cells showed staining for GST Alpha and Pi in 88 and 97 percent, parietal cells in 93 and 67 percent, and chief cells in 82 and 30 percent, respectively. No correlation was observed between the amount or pattern of GST Alpha or Pi in carcinomas and the clinical and pathological characteristics of the patients. So it can be concluded that both GST Alpha and Pi cannot be considered as prognostic factors for gastric cancer.

Adult↗

PubMedDate not supplied

Glutathione S-transferases in gastric carcinomas and in adjacent normal gastric epithelium: immunohistochemical and biochemical analyses.

Glutathione S-transferases (GSTs) are enzymes involved in the detoxification of xenobiotics and are divided into four subclasses. Alpha, Mu, Pi and Theta. Most human gastrointestinal tumors contain increased amounts of GST Pi. In order to compare data on the expression of GSTs obtained by biochemical as well as immunohistochemical methods, we characterized the presence of GST Alpha and Pi by Western blot analysis and immunohistochemistry in 22 samples of human gastric carcinoma and adjacent non-neoplastic mucosa. Biochemical analyses revealed the presence of GST Alpha and Pi in 95% and 91% of normal tissues and in 82% and 100% of tumor specimens, respectively. Immunohistochemically all cases of normal gastric tissue stained for both GST Alpha and Pi, whereas immunostaining for GST Alpha and Pi was seen in 36% and 100% of the gastric tumor specimens, respectively. No statistically significant correlation however was observed between biochemical and immunohistochemical determination of GST Alpha and Pi both in normal as well as in malignant tissue. The absence of a statistically significant correlation between biochemical and immunohistochemical determination of GST Alpha and Pi implies that a high degree of caution must be taken in interpretating data derived solely from biochemical or immunohistochemical assays.

Adult↗