Quantitative aspects in the assessment of liver injury.
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Liver function data are usually difficult to use in their original form when one wishes to compare the hepatotoxic properties of several chemical substances. However, procedures are available for the conversion of liver function data into quantal responses. These permit the elaboration of dose-response lines for the substances in question, the calculation of median effective doses and the statistical analysis of differences in liver-damaging potency. These same procedures can be utilized for estimating the relative hazard involved if one compares the liver-damaging potency to the median effective dose for some other pharmacologie parameter. Alterations in hepatic triglycerides, lipid peroxidation, and the activities of various hepatic enzymes can also be quantitiated in a dose-related manner. This permits the selection of equitoxic doses required for certain comparative studies and the selection of doses in chemical interaction studies. The quantitative problems involved in low-frequency adverse reactions and the difficulty these present in the detection of liver injury in laboratory animals are discussed. (+info)
Activities of citrate synthase, NAD+-linked and NADP+-linked isocitrate dehydrogenases, glutamate dehydrogenase, aspartate aminotransferase and alanine aminotransferase in nervous tissues from vertebrates and invertebrates.
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1. The activities of citrate synthase and NAD+-linked and NADP+-linked isocitrate dehydrogenases were measured in nervous tissue from different animals in an attempt to provide more information about the citric acid cycle in this tissue. In higher animals the activities of citrate synthase are greater than the sum of activities of the isocitrate dehydrogenases, whereas they are similar in nervous tissues from the lower animals. This suggests that in higher animals the isocitrate dehydrogenase reaction is far-removed from equilibrium. If it is assumed that isocitrate dehydrogenase activities provide an indication of the maximum flux through the citric acid cycle, the maximum glycolytic capacity in nervous tissue is considerably greater than that of the cycle. This suggest that glycolysis can provide energy in excess of the aerobic capacity of the tissue. 2. The activities of glutamate dehydrogenase are high in most nervous tissues and the activities of aspartate aminotransferase are high in all nervous tissue investigated. However, the activities of alanine aminotransferase are low in all tissues except the ganglia of the waterbug and cockroach. In these insect tissues, anaerobic glycolysis may result in the formation of alanine rather than lactate. (+info)
Blockade of type beta transforming growth factor signaling prevents liver fibrosis and dysfunction in the rat.
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We eliminated type beta transforming growth factor (TGF-beta) signaling by adenovirus-mediated local expression of a dominant-negative type II TGF-beta receptor (AdCATbeta-TR) in the liver of rats treated with dimethylnitrosamine, a model of persistent liver fibrosis. In rats that received a single application of AdCATbeta-TR via the portal vein, liver fibrosis as assessed by histology and hydroxyproline content was markedly attenuated. All AdCATbeta-TR-treated rats remained alive, and their serum levels of hyaluronic acid and transaminases remained at low levels, whereas all the AdCATbeta-TR-untreated rats died of liver dysfunction. The results demonstrate that TGF-beta does play a central role in liver fibrogenesis and indicate clearly in a persistent fibrosis model that prevention of fibrosis by anti-TGF-beta intervention could be therapeutically useful. (+info)
Phase I and pharmacokinetic study of the topoisomerase II catalytic inhibitor fostriecin.
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We conducted a phase I and pharmacokinetic study of the topoisomerase II catalytic inhibitor fostriecin. Fostriecin was administered intravenously over 60 min on days 1-5 at 4-week intervals. Dose was escalated from 2 mg m(-2) day(-1) to 20 mg m(-2) day(-1) in 20 patients. Drug pharmacokinetics was analysed with high performance liquid chromatography with UV-detection. Plasma collected during drug administration was tested in vitro for growth inhibition of a teniposide-resistant small-cell lung cancer (SCLC) cell line. The predominant toxicities were elevated liver transaminases (maximum common toxicity criteria (CTC) grade 4) and serum creatinine (maximum CTC grade 2). These showed only a limited increase with increasing doses, often recovered during drug administration and were fully reversible. Duration of elevated alanine-amino transferase (ALT) was dose-limiting in one patient at 20 mg m(-2). Other frequent toxicities were grade 1-2 nausea/vomiting, fever and mild fatigue. Mean fostriecin plasma half-life was 0.36 h (initial; 95% CI, 0-0.76 h) and 1.51 h (terminal; 95% CI, 0.41-2.61 h). A metabolite, most probably dephosphorylated fostriecin, was detected in plasma and urine. No tumour responses were observed, but the plasma concentrations reached in the patients were insufficient to induce significant growth inhibition in vitro. The maximum tolerated dose (MTD) has not been reached, because drug supply was stopped at the 20 mg m(-2) dose level. However, further escalation seems possible and is warranted to achieve potentially effective drug levels. Fostriecin has a short plasma half-life and longer duration of infusion should be considered. (+info)
Influences of Kupffer cell stimulation and suppression on immunological liver injury in mice.
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AIM: To study the possible involvement of Kupffer cells (KC) in immunological liver injury in mice. METHODS: Liver injury was induced by i.v. injection of Bacillus Calmette-Guerin (BCG) 5 x 10(7) viable bacilli followed by i.v. injection of lipopolysaccharides (LPS) 7.5 micrograms to each mouse. Indian ink and silica were i.v. injected to suppress KC and retinol was given po to stimulate KC in these mice. Plasma alanine aminotransferase (AlaAT), aspatate aminotransferase (AspAT), nitric oxide (NO), and liver tissue were examined. RESULTS: Injection of LPS following BCG injection resulted in a remarkable elevation of plasma NO, AlaAT, and AspAT levels, and severe liver damage. The damages were enhanced by the activation of KC with retinol and reduced by suppression of KC with silica and Indian ink. CONCLUSION: The degree of liver injury induced by BCG + LPS is closely correlated with the status of KC, and NO from KC plays an important role in the pathogenesis of the liver damage in mice. (+info)
Effect of epidermal growth factor on cultured rat hepatocytes poisoned by CCl4.
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AIM: To study the effects of epidermal growth factor (EGF) on CCl4-induced primary cultured hepatocytes injury. METHODS: Alanine amino-transferase (AlaAT) and aspartate aminotransferase (AspAT) activities and K+ concentractions were determined by the Auto-biochemistry Assay System. Malondialdehyde (MDA) was determined by thiobarbituric acid method. Radioactivity was determined by liquid scintillometry. Light microscopy and electron microscopy were used. RESULTS: EGF 40 micrograms.L-1 decreased CCl4 (10 mmol.L-1)-induced damages of rat primary cultured hepatocytes by decreasing AlaAT and AspAT leakage and MDA production, and promoted RNA and DNA synthesis, with a high positive correlation between intracellular K+ leakage and DNA syntheses (r = 0.99, P < 0.01). Cytopathological study showed that EGF decreased damage of liver cells. CONCLUSION: EGF maintains the stability of cellular lipid membrane and promotes syntheses of RNA and DNA of hepatocytes, and intracellular K+ transference is a promotor of the message transmission of DNA synthesis. (+info)
Continuous versus intermittent portal triad clamping for liver resection: a controlled study.
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OBJECTIVE: The authors compared the intra- and postoperative course of patients undergoing liver resections under continuous pedicular clamping (CPC) or intermittent pedicular clamping (IPC). SUMMARY BACKGROUND DATA: Reduced blood loss during liver resection is achieved by pedicular clamping. There is controversy about the benefits of IPC over CPC in humans in terms of hepatocellular injury and blood loss control in normal and abnormal liver parenchyma. METHODS: Eighty-six patients undergoing liver resections were included in a prospective randomized study comparing the intra- and postoperative course under CPC (n = 42) or IPC (n = 44) with periods of 15 minutes of clamping and 5 minutes of unclamping. The data were further analyzed according to the presence (steatosis >20% and chronic liver disease) or absence of abnormal liver parenchyma. RESULTS: The two groups of patients were similar in terms of age, sex, nature of the liver tumors, results of preoperative assessment, proportion of patients undergoing major or minor hepatectomy, and nature of nontumorous liver parenchyma. Intraoperative blood loss during liver transsection was significantly higher in the IPC group. In the CPC group, postoperative liver enzymes and serum bilirubin levels were significantly higher in the subgroup of patients with abnormal liver parenchyma. Major postoperative deterioration of liver function occurred in four patients with abnormal liver parenchyma, with two postoperative deaths. All of them were in the CPC group. CONCLUSIONS: This clinical controlled study clearly demonstrated the better parenchymal tolerance to IPC over CPC, especially in patients with abnormal liver parenchyma. (+info)
Folate nutriture alters choline status of women and men fed low choline diets.
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Choline and folate share methylation pathways and, in studies of rats, were shown to be metabolically inter-related. To determine whether choline status is related to folate intake in humans, we measured the effect of controlled folate depletion and repletion on the plasma choline and phosphatidylcholine concentrations of 11 healthy men (33-46 y) and 10 healthy women (49-63 y) fed low-choline diets in two separate metabolic unit studies. Total folate intake was varied by supplementing low folate (25 and 56 microg/d for men and women, respectively) and low choline (238 and 147 mg/d for men and women, respectively) diets with pteroylglutamic acid for 2-6 wk following folate-depletion periods of 4-5 wk. The low folate/choline intakes resulted in subclinical folate deficiencies; mean plasma choline decreases of 28 and 25% in the men and women, respectively; and a plasma phosphatidylcholine decrease of 26% in the men (P < 0. 05). No functional choline deficiency occurred, as measured by serum transaminase and lipid concentrations. The decreases in choline status measures returned to baseline or higher upon moderate folate repletion and were more responsive to folate repletion than plasma folate and homocysteine. Feeding methionine supplements to the men did not prevent plasma choline depletion, indicating that folate is a more limiting nutrient for these methylation pathways. The results indicate that 1) choline is utilized as a methyl donor when folate intake is low, 2) the de novo synthesis of phosphatidylcholine is insufficient to maintain choline status when intakes of folate and choline are low, and 3) dietary choline is required by adults in an amount > 250 mg/d to maintain plasma choline and phosphatidylcholine when folate intake is low. (+info)