Biochemical changes in blood at lead intoxication and pectin correction

The results of changes in liver biochemical parameters (AST, ALT, alkaline phosphatase, total protein, urea, and bilirubin) indicating the presence and type of liver injury in lead intoxication and subsequent correction with pectin.     

Effect of the composition of branched chain amino acids, taurine, and tryptophan on the amino acid metabolism in experimental models of alcoholism

Ethanol withdrawal after forced alcoholization of rats according to Majchrowicz led to the development of amino acid imbalance in the pool of free amino acids in the liver (increasing levels of alanine, aspartate, glutamate, glutamine and histidine, decreasing levels of glycine, lysine, threonine and taurine) and blood plasma (increasing levels of tyrosine and alanine, decreasing levels of most glycogen aminoacids, branched-chain aminoacids and Lys). Less profound changes were observed after prolonged alcohol intoxication (decreasing levels of alanine, ornitine, citrulline and increasing level of Glu in liver, increasing levels of sulfur-containing compounds, Asp and Lys in blood plasma). Amino acid mixture which contained branched-chain amino acids, taurine and tryptophan administered intragastrically was found to correct levels of sulfur-containing amino acids, threonine, lysine and isoleucine after ethanol withdrawal and to eliminate disorders in urea cycle, exchange of threonine, glycine and phenylalanine after prolonged alcohol intoxication.     

The content of glycogen and its fractions in human hepatocytes in traumatic disease

A cytofluorometric study was made of the total glycogen and its of fractions in liver cells of patients with hard mechanic trauma with or without intoxication. For studying glycogen dynamics in the course of traumatic illness, the aspiration biopsy material was obtained (30 patients) using repeated liver biopsy of one and the same patient. The total glycogen was found to change insignificantly in liver cells of patients with traumatic illness, both under favourable conditions and with intoxication, and at the normal level. The labile glycogen fraction in liver cells of patients with traumatic illness without intoxication is contained almost at the normal level (80-95%) of the total glycogen and is not changed for a long time. At that time the relative content of the labile glycogen fraction decreases appreciably in some cases to 45-50% due to intoxication development. A relative content of the labile glycogen fraction in hepatocytes with hard mechanical intoxication correlates well with the degree of intoxication. This makes hepatocyte glycogen microfluorometry a diagnostic tool in measuring the functional state of liver in the course of intoxication.     

Effect of arginine administration on disturbances of hepatic glutamine metabolism during acute ammonia intoxication in the rat]

The present study is concerned with the effects of L-arginine hydrochloride administration on the disturbances of liver glutamine metabolism following acute ammonia intoxication in the rat. Our results show that arginine administration does not suppress the decrease in the hepatic glutamine level and the marked activation of liver glutaminase I induced by ammonia. These alterations do not therefore appear to be related to the limitation of ammonia detoxication through the urea cycle.     

Endogenous antioxidant defence system in rat liver following mercury chloride oral intoxication

Mercury is a highly toxic metal which induces oxidative stress. Superoxide dismutases, catalase, and glutathion peroxidase are proteins involved in the endogenous antioxidant defence system. In the present study rats were administered orally, by gavage, a single daily dose of HgCl2 for three consecutive days. In order to find a relation between the proteins involved in the antioxidant defence and mercury intoxication, parameters of liver injury, redox state of the cells, as well as intracellular protein levels and enzyme activities of Mn-dependent superoxide dismutase (MnSOD), Cu-Zn-dependent superoxide dismutase (CuZnSOD), catalase, and glutathione peroxidase (GPx) were assayed both in blood and in liver homogenates. HgCl2 at the doses of 0.1 mg/kg produced liver damage which that was detected by a slight increase in serum alanine aminotransferase and gamma glutamyl transferase. Hepatic GSH/GSSG ratio was assayed as a parameter of oxidative stress and a significant decrease was detected, as well as significant increases in enzyme activities and protein levels of hepatic antioxidant defence systems. Changes in both MnSOD and CuZnSOD were parallel to those of liver injury and oxidative stress, while the changes detected in catalase and GPx activities were progressively increased along with the mercury intoxication. Other enzyme activities related to the glutathione redox cycle, such as glutathione reductase (GR) and glucose-6-phosphate dehydrogenase (G6PDH), also increased progressively. We conclude that against low doses of mercury that produce a slight oxidative stress and liver injury, the response of the liver was to induce the synthesis and activity of the enzymes involved in the endogenous antioxidant system. The activities of all the enzymes assayed showed a rapidly induced coordinated response.     

Transition between Acute and Chronic Hepatotoxicity in Mice Is Associated with Impaired Energy Metabolism and Induction of Mitochondrial Heme Oxygenase-1

The formation of protein inclusions is frequently associated with chronic metabolic diseases. In mice, short-term intoxication with 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC) leads to hepatocellular damage indicated by elevated serum liver enzyme activities, whereas only minor morphological changes are observed. Conversely, chronic administration of DDC for several weeks results in severe morphological damage, characterized by hepatocellular ballooning, disruption of the intermediate filament cytoskeleton, and formation of Mallory-Denk bodies consisting predominantly of misfolded keratins, Sqstm1/p62, and heat shock proteins. To evaluate the mechanistic underpinnings for this dichotomy we dissected the time-course of DDC intoxication for up to 10 weeks. We determined body weight change, serum liver enzyme activities, morphologic alterations, induction of antioxidant response (heme oxygenase-1, HO-1), oxidative damage and ATP content in livers as well as respiration, oxidative damage and the presence and activity of HO-1 in endoplasmic reticulum and mitochondria (mtHO-1). Elevated serum liver enzyme activity and oxidative liver damage were already present at early intoxication stages without further subsequent increase. After 2 weeks of intoxication, mice had transiently lost 9% of their body weight, liver ATP-content was reduced to 58% of controls, succinate-driven respiration was uncoupled from ATP-production and antioxidant response was associated with the appearance of catalytically active mtHO-1. Oxidative damage was associated with both acute and chronic DDC toxicity whereas the onset of chronic intoxication was specifically associated with mitochondrial dysfunction which was maximal after 2 weeks of intoxication. At this transition stage, adaptive responses involving mtHO-1 were induced, indirectly leading to improved respiration and preventing further drop of ATP levels. Our observations clearly demonstrate principally different mechanisms for acute and chronic toxic damage.     

Carbohydrate, protein and glycoprotein metabolism by the guinea-pig liver in chronic metribuzin poisoning

Male guinea-pigs weighing 400-600 g, 8 months old, were given metribuzin directly into the gastric lumen over a period of 30 days (20 animals) or 90 days (20 animals) 6 times a week. In the liver of the poisoned animals, the glycogen level and the AspAT and AlAT activities, while in the serum the total protein and the fractions albumin, alpha 1-globulin and gamma-globulin significantly decreased; serum glucose and the serum fractions alpha 2-globulin and beta-globulin, each showed an increase. The glycogen level in the liver, total protein, glucose as well as the alpha 1 and alpha 2 globulin fractions in the serum showed not appreciable difference between 30 and 90 days of intoxication. After 90 days of metribuzin treatment AspAT and AlAT dropped in the liver and rose in the serum, in comparison to the 30-day values. As to the parameters of glycoprotein metabolism, the intoxicated animals showed a significant decrease and increase in concentration of hexosamines and sialic acids in the liver and serum, respectively. Metribuzin intoxication also cause a significant decrease in activity of glucosamine phosphate isomerase and significant increase in activity of glycosidases in the liver. The results suggest that metribuzin disturbs the metabolism of carbohydrates, proteins and glycoproteins in the guinea-pig liver.     

Inhibition of the initiation of hepatic protein synthesis during ethionine mediated ATP depletion in vivo: modification to ribosomal subunits, evidence of impaired ternary complex formation and a subcellular redistribution of eIF-2 alpha

Acute ethionine intoxication is known to induce a reversible hepatic injury in female rats by reducing the level of hepatic ATP. The injury indirectly impairs the initiation of hepatic protein synthesis, with resultant polysome disaggregation. Administration of adenine rapidly restores the ATP levels and protein synthesis. Analysis of liver polysome and ribosomal subunits reveals that polysome disaggregation occurs following 3 h of the intoxication, and reaggregation occurs following the administration of adenine. Inactive hepatic ribosomes accumulate as monomers and disomes when analysed by sucrose gradient sedimentation in low-salt buffers. High-salt buffers dissociate the inactive ribosomes into the component 40 S and 60 S subunits. The level of higher density, 1.48 g/cc, 40 S subunit increases during the inhibition of protein synthesis, while the lower density, 1.41 g/cc, 40 S subunit species does not change significantly. Hepatic microsomal and cytosolic extracts examined for their ability to support the formation of the ternary complex of eIF-2-GTP and [35S]Met-tRNAi demonstrate that during acute ethionine intoxication, ternary complex formation in the two extracts decrease 65% and 85%, respectively. These changes are coincident with polysome disaggregation. Administration of adenine to reverse the intoxication restores the ternary complex forming ability of the cytosolic extract, but does not affect the activity of the microsomal salt wash extracts. Mixing experiments indicate the accumulation of an inhibitor of ternary complex formation in the microsomal salt wash fraction. The application of quantitative western blotting demonstrates that the level of antigenic eIF-2 alpha in the microsomal salt wash extract increases 31% during the inhibition. These observations are consistent with the idea that the inhibition of the initiation of hepatic protein synthesis induced by ethionine is mediated by eIF-2 alpha phosphorylation. The latter results in an inhibition of ternary complex formation, redistribution of eIF-2 to the microsome fraction, polysomal disaggregation, and accumulation of inactive ribosomal subunits.     

Acute and chronic ethanol consumption differentially impact pathways limiting hepatic protein synthesis

This review identifies the various pathways responsible for modulating hepatic protein synthesis following acute and chronic alcohol intoxication and describes the mechanism(s) responsible for these changes. Alcohol intoxication induces a defect in global protein synthetic rates that is localized to impaired translation of mRNA at the level of peptide-chain initiation. Translation initiation is regulated at two steps: formation of the 43S preinitiation complex [controlled by eukaryotic initiation factors 2 (eIF2) and 2B (eIF2B)] and the binding of mRNA to the 40S ribosome (controlled by the eIF4F complex). To date, alcohol-induced alterations in eIF2 and eIF2B content and activity are best investigated. Ethanol decreases eIF2B activity when ingested either acutely or chronically. The reduced eIF2B activity most likely is a consequence of twofold increased phosphorylation of the alpha-subunit of eIF2 on Ser(51) following acute intoxication. The increase in eIF2alpha phosphorylation after chronic alcohol consumption is the same as that induced by acute ethanol intoxication, and protein synthesis is not further reduced by long-term alcohol ingestion despite additional reduced expression of initiation factors and elongation factors. eIF2alpha phosphorylation alone appears sufficient to maximally inhibit hepatic protein synthesis. Indeed, pretreatment with Salubrinal, an inhibitor of eIF2alpha(P) phosphatase, before ethanol treatment does not further inhibit protein synthesis or increase eIF2alpha phosphorylation, suggesting that acute ethanol intoxication causes maximal eIF2alpha phosphorylation elevation and hepatic protein synthesis inhibition. Ethanol-induced inhibition of hepatic protein synthesis is not rapidly reversed by cessation of ethanol consumption. In conclusion, sustained eIF2alpha phosphorylation is a hallmark of excessive alcohol intake leading to inhibition of protein synthesis. Enhanced phosphorylation of eIF2alpha represents a unique response of liver to alcohol intoxication, because the ethanol-induced elevation of eIF2alpha(P) is not observed in skeletal muscle or heart.     

Perturbations in nitrogen metabolism of brain and liver of rat following repeated benthiocarb administration

Effects of repeated administration of benthiocarb on the nitrogen metabolism of hepatic and neuronal systems have been studied. Repeated benthiocarb treatment was associated with significant decrease in proteins with a concomitant increase in free amino acids (FAA) and specific activity levels of proteases suggesting impaired protein synthesis or elevated proteolysis. The glycogenic aminotransferases showed a significant elevation in both the tissues indicating high feeding of ketoacids into oxidative pathway for efficient operation of TCA cycle to combat energy crisis during induced benthiocarb stress. However, the activity levels of branched-chain aminotransferases decreased suggesting their reduced contribution of intermediates to TCA cycle. A comparative evaluation of the activity levels of ammonogenic enzymes, AMP deaminase, adenosine deaminase and glutamate dehydrogenase (GDH) indicated that ammonia was mostly contributed by nucleotide deamination rather than by oxidative deamination. GDH exhibited reduced activity due to low availability of glutamate. In accordance with increased levels of urea, the activity levels of arginase, a terminal enzyme of urea cycle was increased suggesting increased urea cycle operation in order to combat the increased ammonia content. As the presence of urea cycle in the brain is rather doubtful, the conversion of ammonia to glutamine for the synthesis of GABA is envisaged in brain whereas in liver, excess ammonia was converted to urea through ornithine-arginine reacting system. The increased glutaminase activity observed during benthiocarb intoxication is accounted for counteracting acidosis or maintenance of metabolic homeostasis. Arginase, a terminal enzyme of ornithine cycle showed increased activity denoting the efficient potentiality of tissues to avert ammonia toxicity. The changes observed in tissues of rat administered with benthiocarb reflects a shift in nitrogen metabolism for efficient mobilization of end products of protein catabolism.     

The prostaglandin and cyclic nucleotide levels in the organs of mice with experimental anthrax intoxication]

In this work the influence of Bacillus anthracis toxin, introduced intraperitoneally in a dose of LD100, on the content of prostaglandins E and F2 alpha, 6-ketoprostaglandin F1 alpha, thromboxane, cAMP and cGMP in the lungs, heart, liver and spleen of BALB/c mice in the time course of experimental intoxication has been studied. The concentration and proportion of prostaglandins and cyclic nucleotides have been shown to undergo-sharp changes in all organs under study in the process of intoxication. The level and proportion of prostaglandins in the lungs ensures the development of vaso- and bronchodilatation processes even at early stages of the action of the toxin. B. anthracis toxin sharply increases the content of cGMP in the organs under study and cAMP in the liver. The activating effect on the adenylate cyclase system of tissue cells is not linked with the action of the edematous factor of the toxin. The role of cyclic nucleotides and prostaglandins in the development of pulmonary edema in intoxication with B. anthracis toxin is discussed.     

Plasma and liver amino acids in rats after administration of ethanol or acetaldehyde

The changes in the level and pattern of free amino acids in plasma and liver after ethanol or acetaldehyde intoxication has been investigated in rats. After administration of 30% (w/v) ethanol, 6 g kg-1, or 1.5% (w/v) acetaldehyde, 0.3 ml kg-1, for 4 weeks we found a decrease in plasma and liver branched-chain amino acids and an increase in plasma aromatic amino acids and methionine. The results are analogous to those found in studies of damaged liver.     

Alpha-fetoprotein and serum hormone levels following liver intoxication with carbon tetrachloride

Rats were submitted to carbon tetrachloride intoxication at two different doses. Serum level of estradiol, progesterone, cortisol and thyroxin were measured by radioimmunoassays and correlated with the histological evidences of liver regeneration and serum alpha-fetoprotein levels. A two fold increase of progesterone was observed 48hrs after CCl₄ administration. Cortisol levels were moderately increased at both doses of CCl₄. Despite the five fold increase of alpha-fetoprotein (which is the major estradiol binding protein in these sera) no changes in estradiol levels were observed. Thyroxin levels showed a two fold increase after 72hrs. This result contrasts with the drop of this hormone after partial hepatectomy which has been previously published. These experiments show that a new hormonal imbalance (directly or indirectly due to the toxic) is involved both in liver regeneration and alpha-feto-protein synthesis.     

Effect of alcohol intoxication on ascorbic and dehydroascorbic acid levels in rat tissue. and human blood

It is found that acute ethanol intoxication is accompanied by a decrease in the ascorbic acid content in the brain, liver and kidneys. The content of dehydroascorbic acid in kidneys in this case increases and in the brain tends to decrease. The chronic alcohol intoxication of rats has an opposite (as compared to the acute intoxication) effect on changes in the content of ascorbic and dehydroascorbic acids in the studied organs. People with chronic alcohol intoxication have the lower content of ascorbic acid in blood plasma and the higher content in erythrocytes, the content of dehydroascorbic acid being increased.     

A proteomics approach to identify protein expression changes in rat liver following administration of 3,5,3'-triiodo-L-thyronine

We analyzed whole cell protein content of rat liver following T3 administration. Fourteen differentially expressed proteins were unambiguously identified and were involved in substrates and lipid metabolism, energy metabolism, detoxification of cytotoxic products, calcium homeostasis, amino acid catabolism, and the urea cycle. This study represents the first systematic identification of T3-induced changes in liver protein expression profile and provides novel information at the molecular, cellular, and tissue level of T3 action.     

Dietary regulation of ornithine transcarbamylase mRNA in liver and small intestine

In the rat, changes in dietary protein intake give rise to changes in the levels of ornithine transcarbamylase (OTC) in liver and small intestine--an increase in liver and decrease in small intestine. The changes in enzyme level are accompanied by similar changes in levels of specific mRNA. Thus in liver, there is an increase in the level of specific mRNA when protein intake is increased, whereas in small intestine there is a small decrease. Comparison of changes in specific mRNA with total poly-A-containing RNA showed that the change in OTC mRNA in liver paralleled the change in total RNA levels. In contrast, in small intestine the small decrease in OTC mRNA levels when protein intake was increased was in the face of an increase in the level of total mRNA. Whereas the level of OTC is 20-fold higher in liver than in small intestine, the mRNA level for the enzyme differs by only 2.5-fold.     

Translational control of the circadian rhythm of liver sterol carrier protein

Rat liver sterol carrier protein (SCP), a major regulator of lipid metabolism and transport, undergoes a rapid turnover and dramatic circadian variation in amount. The level of SCP was quantitated by a specific immunochemical assay using an antibody to homogeneous liver SCP. During a 12-h dark, 12-h light cycle, liver exhibits a biphasic pattern in SCP level. A 7-fold increase in SCP (i.e. from 1 to 7 mg/g of liver) occurs in the dark period, peaking at the midpoint and returning to basal levels by the beginning of the light period. A similar but smaller pattern of variation in SCP amount occurs in the light cycle. To elucidate the basic mechanism responsible for these changes in SCP level, the relative synthetic rate of SCP and mRNA functional activity for SCP were measured during the dark-light cycle. Alterations in the rate of SCP synthesis can account for the variations in SCP concentration. Although large changes occur in relative synthetic rate, no significant changes were found in the level of mRNA for SCP. Therefore, the circadian rhythm in SCP synthesis and amount does not reflect variations in the concentration of mRNA for SCP, but instead is caused by some mechanism controlling the efficiency of translation of SCP mRNA.     

Phosphoinositides of the brain and liver of rats in ethanol poisoning]

Alcohol intoxication induced in the rat brain significant decrease in the monophosphoinositides level, but the di- and triphosphoinositides quantity did not change; the content of all the three studied fractions of the inositol-containing phospholipids in the liver decreased. The tendency to retain the normal level of di- and triphosphoinositides in the brain following alcohol intoxication may be considered as an important factor providing physiological condition of the brain metabolism.     

Concentrations of protein sulfhydryl and amino groups in the brain during acute and chronic alcoholic intoxication

The content of sulphydryl and amine groups in water- and salt- soluble proteins of different areas of the rat brain was studied as affected by acute and chronic alcohol intoxication. With a relatively unchanged content of sulphydryl groups, noticeable variations are observed in the level of amine groups, most pronounced in proteins of the intermediate and middle areas of the brain. Under chronic intoxication the greatest changes in the content of the functional groups occur on the fourth day after cessation of the alcohol administration, when changes in the clinical state of the animals are most pronounced. It is supposed that the found shifts are caused by an acetaldehyde reversible blockade of amino groups and by the conformation rearrangement of protein molecules.     

Protective effect of blackcurrant on liver cell membrane of rats intoxicated with ethanol

Chronic ethanol intoxication oxidative stress participates in the development of many diseases. Nutrition and the interaction of food nutrients with ethanol metabolism may modulate alcohol toxicity. One such compound is blackcurrant, which also has antioxidant abilities. We investigated the effect of blackcurrant as an antioxidant on the composition and electrical charge of liver cell membranes in ethanol-intoxicated rats. Qualitative and quantitative phospholipid composition and the presence of integral membrane proteins were determined by high-performance liquid chromatography. Electrophoresis was used to determine the surface charge density of the rat liver cell membranes. Ethanol intoxication is characterized by changes in cell metabolism that alter the structure and function of cell membrane components. Ethanol increased phospholipid levels and altered the level of integral proteins as determined by decreased phenylalanine, cysteine, and lysine. Ethanol significantly enhanced changes in the surface charge density of the liver cell membranes. Administration of blackcurrant to rats intoxicated with ethanol significantly protected lipids and proteins against oxidative modifications. It is possible that the beneficial effect of blackcurrant is connected with its abilities to scavenge free radicals and to chelate metal ions.