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Y Israel

Publications and source records attributed to Y Israel.

At least 55 records · Page 3Linked to original sources
PubMed1993

A new approach for the rapid detection of common and atypical aldehyde dehydrogenase alleles.

A strong protection against the development of alcoholism is exerted by a point mutation in the gene coding for low Km aldehyde dehydrogenase (ALDH), i.e. ALDH2. We report a non-radioactive method for determining the common and atypical human mitochondrial aldehyde dehydrogenase (ALDH2) genotypes. This method is based on the fact that the base change (G-->A) in Exon 12 of the ALDH2 gene abolishes an Eco57 I restriction site (CTGAAG-->CTAAAG). A GC-clamp attached oligonucleotide was designed to yield a 176 base pair product by the polymerase chain reaction. After amplification, the resulting fragment containing the normal nucleotide sequence is cut by Eco57 I into two segments (131 base pairs + 45 base pairs) while the fragment containing the mutated sequence remains intact (176 base pairs). These are visualized by staining with ethidium bromide on agarose gels without blotting, hybridization or autoradiography.

Alcoholism↗
PubMed1993

Acetate-induced adenosine mediated effects of ethanol.

Ethanol administration leads to a marked increase in hepatic blood flow, resulting from an increase in mesenteric blood flow. Studies presented indicate that the increase in portal blood flow induced by ethanol is mediated by acetate. Acetate infusion at rates which achieve blood concentrations equal to those following ethanol administration, fully reproduce this effect of ethanol. The adenosine receptor blocker 8-phenyltheophilline (8PT) fully abolishes the increase in portal blood flow induced by both ethanol and acetate. We have proposed that the extrahepatic metabolism of acetate into acetyl-CoA yields AMP and adenosine. Studies also indicate that adenosine receptor activation has a major contribution to the CNS depressant effects of ethanol at low concentrations of ethanol (below 1.5 g/kg) where the production of acetate is near maximal and the physico-chemical effects of ethanol are minor. Acetate significantly potentiates the CNS depressant effects of general anesthetics. Data to be presented indicate that for some behaviours, acetate through an adenosine-receptor activation potentiates the effects of ethanol while in other behavioural tests they antagonize ethanol effects.

Acetates↗
PubMed1993

Effect of propylthiouracil on the ethanol-induced increase in liver oxygen consumption in awake rats.

It has been postulated that the beneficial effects of the antithyroid drug propylthiouracil in the treatment of alcoholic liver disease depend primarily on the action of propylthiouracil in suppressing the increase in hepatic oxygen consumption induced by ethanol. The evidence for this effect of propylthiouracil is derived from studies in which liver oxygen consumption has been determined in in vitro preparations. In our study the effects of ethanol and propylthiouracil on liver oxygen consumption were assessed in vivo in an unrestrained and unanesthetized rat model, where liver blood flow and hepatic vein and portal vein oxygen content can be measured. Data show that the liver oxygen consumption increased in rats treated with ethanol-containing liquid diets for 4 to 6 wk, both on withdrawal of alcohol (30%, p < 0.01), and after readministration of ethanol (50%, p < 0.01). Single-dose ethanol administration increased portal tributary blood flow without affecting hepatic arterial blood flow in both controls and rats withdrawn from long-term ethanol treatment. Long-term ethanol administration per se had no effect on portal tributary blood flow; however, hepatic arterial blood flow was increased by 38% (p < 0.01). Treatment with propylthiouracil for 5 days resulted in complete suppression of the increase in liver oxygen consumption induced by long-term ethanol administration. Propylthiouracil treatment also attenuated the increase in portal tributary blood flow after the administration of a single dose of ethanol. These determinations were made 24 hr after the last dose of propylthiouracil.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Cloning and nucleotide sequence of human liver cDNA encoding for cystathionine gamma-lyase.

We have cloned and sequenced a full-length cDNA (1083 bp) encoding the human liver cystathionine-gamma-lyase enzyme (cystathionase). The human cystathionase sequence presented a substantial deletion of 132 bases (44 amino acids) compared to that reported for rat cystathionase, and of 135 bases (45 amino acids) compared to that reported for yeast cystathionase. After re-alignment for the missing nucleotides, the human cDNA sequence shows significant amino acid homology to that for the rat enzyme (85%) and the yeast enzyme (50%). A search for an undeleted cDNA, by the polymerase chain reaction, yielded a second clone which contained the missing 132 bases. Flanking nucleotides in the latter clone were identical to those in the cDNA clone containing the deletion. The two forms of human cystathionase deduced from the two cDNA clones may be derived from two different genes or may be splice variants.

Amino Acid Sequence↗
PubMed1992

Characteristics of a new urine, serum, and saliva alcohol reagent strip.

We have tested an ethanol reagent strip developed at the Addiction Research Foundation of Ontario. Alcohol dehydrogenase and nicotinamide adenine dinucleotide, in the presence of pyrazole, react with ethanol to yield acetaldehyde plus reduced nicotinamide adenine dinucleotide. The latter reduces iodonitrotetrazolium chloride in the presence of diaphorase, generating an intense red color. The rate of color development is proportional to the concentration of ethanol. Color is compared at a specific time against a calibrated color scale ranging from green (negative) to red, representing alcohol concentrations of 0, 25, 50, 100, 200, and 400 mg/dl (0-0.4%; 0-87 mmol/liter). We were able to interpolate the color observed between the calibrated blocks. When tested on urine, serum/plasma, and saliva, ethanol concentration determined by the reagent strip correlates well with ethanol concentration as determined by gas chromatography or by automated enzymatic analysis (r = 0.92-0.98, p less than 0.001; slope 0.83-1.16). The reagent strip was shown to be used appropriately by nonexperienced individuals following a 1-min explanation (reagent strip values, r = 0.92; p less than 0.001, slope = 0.97, versus gas chromatography). The reagent strip does not react with methanol (wood alcohol), isopropanol (rubbing alcohol), and ethylene glycol (antifreeze) often found in accidental poisonings. In 379 clinical samples obtained without exclusion criteria from 12 hospital emergency rooms and a liver clinic, the sensitivity of the reagent strip in detecting ethanol was 98%. Specificity was 99%. The reagent strip was found to have virtually unlimited stability under refrigeration (4 degrees C) and to be stable for 3 to 4 months at room temperature (22-23 degrees C).(ABSTRACT TRUNCATED AT 250 WORDS)

Alcohol Drinking↗
PubMed1992

Hemoglobin-acetaldehyde adducts in human alcohol abusers.

BACKGROUND: Previous observations have indicated that acetaldehyde can bind irreversibly to proteins in vitro, yielding immunogenic determinants, which can stimulate production of antibodies against the acetaldehyde adducts. EXPERIMENTAL DESIGN: We have developed sensitive two-site enzyme-linked immunosorbent assays for measurement of hemoglobin-acetaldehyde adducts. These adducts were measured from the red blood cells of 169 alcohol abusers, 66 social drinkers, 18 abstainers, and 73 hospitalized control patients. RESULTS: While the immunoreactive acetaldehyde adducts were found to be increased in 50% of the alcohol abusers (p less than 0.01), 24% of the social drinkers (p less than 0.05) also exceeded the reference interval obtained from the abstaining controls. Adducts were also increased in 17 (23%) hospitalized controls, seven of whom could retrospectively be verified as heavy drinkers. Upon abstinence from ethanol, the adducts decreased during a period of 1-3 weeks. CONCLUSIONS: The studies indicate that acetaldehyde adducts are frequently elevated in the erythrocytes of human alcohol consumers. Measurements of such adducts may prove to be valuable in the early identification of excessive alcohol consumption and of hazardous social drinking and in the comprehensive assessment and treatment of patients with alcohol-related diseases.

Acetaldehyde↗
PubMed1992

Hypersensitivity to acetaldehyde-protein adducts.

Acetaldehyde, the first product in the metabolism of ethanol, is known to condense with plasma proteins, forming stable adducts. We have previously shown that these adducts can be recognized as foreign by the immune system. In the present study the existence of type I hypersensitivity-mediating antibodies against these adducts was investigated in humans and in animals. Immunization of mice with acetaldehyde-protein condensates, followed by adoptive transfer of splenocytes, led to the production of IgE anti-acetaldehyde adducts. A monoclonal IgE antibody was obtained by the hybridization technique. This antibody recognized acetaldehyde adducts, independently of the carrier protein used, indicating that the acetaldehyde moiety behaves as a hapten. The affinity of the antibody for the acetaldehyde adduct of polylysine was 7 orders of magnitude higher than that for polylysine. Passive immunization by intradermal or intravenous administration of this monoclonal antibody to rats rendered the animals hypersensitive to acetaldehyde-protein conjugates, as shown by marked anaphylaxis. A study was conducted to determine the existence of naturally occurring hypersensitivity reactions to alcohol in > 1000 non-Oriental individuals. A prevalence of severe hypersensitivity reactions of 0.46% was found. The reactions were severe enough to deter these individuals from consuming all types of alcoholic beverages. Individuals presenting such reactions had significantly elevated levels of circulating anti-acetaldehyde-protein IgE antibodies.

Acetaldehyde↗
PubMed1992

Acetaldehyde-modified hemoglobin as a marker of alcohol consumption: comparison of two new methods.

We examined the diagnostic value of acetaldehyde-hemoglobin adducts in the detection of heavy drinking and alcoholism. Acetaldehyde adducts from red cells were measured by new chromatographic and immunologic methods. The study population included 20 men with well-documented histories of chronic alcoholism, 18 men who were heavy drinkers, 22 male healthy control subjects, and 8 control subjects with liver disease that was not related to alcohol use. In addition, 20 healthy volunteers and 5 control subjects participated in the study to determine the effect of an acute dose of ethanol. The results that were obtained by the two new methods correlated significantly (r = 0.38, p = 0.002). With both methods, the concentrations of acetaldehyde-hemoglobin adducts were found to be significantly higher in red cells of heavy drinkers (p less than 0.001) and subjects with alcoholism (p less than 0.001) when compared with control subjects. Acetaldehyde-modified hemoglobins appear to have at least the same sensitivity (chromatographic determination = 50% and immunologic determination = 50%) to detect heavy drinking as the most widely accepted conventional biochemical markers of alcohol abuse, gamma-glutamyltransferase (39%) or mean corpuscular volume (17%). In a group of 20 healthy volunteers, acetaldehyde-hemoglobin adducts increased significantly even after a single high dose of ethanol (2 gm/kg), whereas there was no change in the conventional markers of alcohol consumption at the same time. Acetaldehyde-hemoglobin adducts assays should be useful for the detection of heavy drinking in clinical settings.

Acetaldehyde↗
PubMed1991

Histochemical demonstration of sinusoidal gamma-glutamyltransferase activity by substrate protection fixation: comparative studies in rat and guinea pig liver.

Most histochemical methods for the detection of an enzymatic activity are preceded by tissue fixation with chemical agents that partially inactivate the enzymes. It is well known that substrates exert a marked protection against fixative-induced inactivation. The conventional histochemical methods for the demonstration of hepatic gamma-glutamyltransferase activity have not been successful in detecting the activity of the enzyme on the sinusoidal side of the hepatocytes despite mounting biochemical evidence for its presence on that pole of the hepatocyte. Under conventional fixation the enzymatic activity in hepatocytes is only seen on the bile canalicular side. This may be the result of a preferential protective effect of gamma-glutamyltransferase by its normal substrate, glutathione, present in the bile canaliculus at concentrations 500 times higher than in the sinusoidal lumen (8 mmol/L vs. 10 to 20 mumol/L). To test this hypothesis and to reduce the degree of fixative-induced inhibition of the enzyme activity, glutathione was either incorporated in the fixative solution or the livers were perfused with high concentrations of glutathione (10 mmol/L) before fixation. Our results histochemically demonstrate, in the normal adult rat liver, the existence of gamma-glutamyltransferase activity not only on the bile canalicular pole but also on the sinusoidal pole of the hepatocytes. Visualization of the enzyme activity on the sinusoidal pole is dependent on glutathione protection. Guinea pig livers, which present a 10-fold higher gamma-glutamyltransferase activity than rat livers (similar to that in human beings), showed marked sinusoidal gamma-glutamyltransferase activity even in the absence of glutathione protection. Glutathione protection further increased this sinusoidal activity.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Trauma in cirrhosis: an indicator of the pattern of alcohol abuse in different societies.

While some morbidities associated with the excessive use of alcohol are related to the total amount of alcohol consumed--cirrhosis being an example--other pathologies, such as trauma and those of psycho-social origin, are mainly related to the frequency of acute alcoholic intoxication rather than to the total amount consumed. The balance between these two types of alcohol-associated morbidities can provide an indication of the relative frequency of intoxication, and thus of the pattern of alcohol abuse in a population. Since trauma is highly associated with acute alcoholic intoxication, the prevalence of bone fractures was determined in cirrhotics in nine countries. The prevalence of rib and vertebral fractures on routine chest x-rays showed a 17-fold variation in the different countries, from 2% and 6% in Spain and Italy to 30% and 34% in Canada and the USA, suggesting marked differences in the pattern of alcohol abuse to intoxication. Conversely, the prevalence of cirrhosis is twice as high in Spain and Italy than in Canada and the USA. A strong positive correlation between per capita consumption and cirrhosis mortality (r = 0.86; p less than 0.01) exists among the nine countries studied, while the correlation between per capita alcohol consumption and the prevalence of trauma is not statistically significant (r = 0.40). Supporting a strong association between trauma and alcoholic intoxication, the prevalence of trauma was found to be highly correlated: r = 0.88, p less than 0.002, with the degree of concern for the psycho-social consequences of alcohol abuse in the different countries. Data indicate that trauma can be used as an objective indicator to assess the pattern of alcohol abuse in a population.

Alcohol Drinking↗
PubMed1991

Central nervous system effects of acetate: contribution to the central effects of ethanol.

Acetate, resulting from ethanol metabolism in the liver, is released into the circulation and is utilized in a number of tissues, including the brain. In its metabolism, acetate leads to the production of adenosine, a powerful physiological mediator. We have investigated the effect of acetate on central nervous system (CNS) function in rodents. Sodium acetate in doses resulting in blood concentrations comparable to those attained after the administration of 1 to 2 g/kg ethanol, had significant CNS effects. Both ethanol and acetate produced a dose-dependent impairment of motor coordination. This effect of acetate was fully blocked by the adenosine receptor blocker 8-phenyltheophylline (8PT), whereas the dose-response relationship for ethanol was shifted to the right by about 30%. The inspired concentration of sevoflurane to achieve anesthesia was significantly reduced by both these agents. General anesthesia was potentiated in a dose-dependent fashion by ethanol and by acetate. The effect of acetate on anesthetic requirements was fully blocked by 8PT. The effect of ethanol on sevoflurane anesthetic requirements was inhibited by 22 to 35% by 8PT. Locomotor activity in mice was reduced by acetate in a dose-dependent fashion, an effect that was also fully blocked by 8PT. On the other hand, ethanol at a dose of 1 to 2 g/kg increased locomotor activity. This likely results from a direct stimulatory effect of ethanol, opposed by an inhibitor effect of acetate. The administration of 8PT enhanced the stimulation of locomotor activity induced by ethanol. In conclusion, acetate, a product of ethanol metabolism has significant CNS effects that can either potentiate or antagonize the effects of the ethanol molecule per se.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetates↗
PubMed1990

Human dopamine D1 receptor encoded by an intronless gene on chromosome 5.

Receptors for dopamine have been classified into two functional types, D1 and D2. They belong to the family of receptors acting through G (or guanine nucleotide-binding) proteins. D2 receptors inhibit adenylyl cyclase, but D1 receptors stimulate adenylyl cyclase and activate cyclic AMP-dependent protein kinases. Dopamine D1 and D2 receptors are targets of drug therapy in many psychomotor disorders, including Parkinson's disease and schizophrenia, and may also have a role in drug addiction and alcoholism. D1 receptors regulate neuron growth and differentiation, influence behaviour and modify dopamine D2 receptor-mediated events. We report here the cloning of the D1 receptor gene, which resides on an intronless region on the long arm of chromosome 5, near two other members of the G-linked receptor family. The expressed protein, encoded by 446 amino acids, binds drugs with affinities identical to the native human D1 receptor. The presence of a D1 receptor gene restriction fragment length polymorphism will be helpful for future disease linkage studies.

Amino Acid Sequence↗
PubMed1990

Cloning of two additional catecholamine receptors from rat brain.

An approach based on the polymerase chain reaction (PCR) was used to isolate additional members of the G-linked receptor family from a rat striatal lambda gtII cDNA library. Priming with one degenerate probe corresponding to highly conserved consensus sequences in the third transmembrane (TM) domain of 15 G-linked receptors and sequences in the phage vector resulted in one clone (G-13) encoding a dopamine D2 receptor variant with a 29 amino acid insert in the third cytoplasmic loop. In addition, the amino acid sequence encoded by clone G-36 contained conserved sequences characteristic of the G-linked class of receptors and displayed sequence homology in TM domains with the beta 2-adrenergic receptor (48%). Two conserved serine residues in TM5 postulated to be part of a ligand binding site in the adrenergic receptor, suggests that G-36 encodes a catecholaminergic receptor. Northern blot analysis confirmed the expression of G-36 in rat brain, but not in kidney, heart and lung. Several strong hybridizing bands to G-36 were obtained in both human and rat genomic DNA. The general PCR strategy employed here should prove to be extremely useful for the isolation of other members of the G-linked receptor family.

Amino Acid Sequence↗
PubMed1990

Role of hepatic gamma-glutamyltransferase in the degradation of circulating glutathione: studies in the intact guinea pig perfused liver.

The role of hepatic gamma-glutamyltransferase in the breakdown of circulating glutathione was studied in the perfused guinea pig liver. Hepatic gamma-glutamyltransferase activity in the guinea pig is sevenfold higher than in the rat and is comparable to its activity in man. Guinea pig livers were found to remove, in a single pass, 50% to 90% of glutathione (10 to 50 mumol/L) added to the portal perfusate. Removal of portal glutathione was totally dependent on the activity of gamma-glutamyltransferase and led to the near quantitative appearance of cysteinyl-glycine and cysteine in the caval perfusate. Glutathione removal by the intact liver followed saturation with a Michaelis constant (Km) of 59 mumol/L for glutathione and a maximum velocity of 235 nmol glutathione/min/gm of liver weight. The capacity of the guinea pig liver to remove circulating glutathione was estimated to be sevenfold to 10-fold higher than its net rate of output of glutathione into the circulation. Inhibition of gamma-glutamyltransferase activity in the perfused liver led to threefold to sixfold increases in the hepatic output of glutathione into the circulation, indicating that more than two thirds of glutathione transported extracellularly is broken down. Data obtained demonstrate a major role of hepatic gamma-glutamyltransferase, both in the removal of portally carried glutathione and in the degradation of glutathione molecules released by the liver itself into the sinusoids. These findings suggest the existence of an intraorgan transport of glutathione in the liver, whereby periportal cells could provide glutathione precursors to pericentral cells.

Animals↗
PubMed1990

Genotyping of mitochondrial aldehyde dehydrogenase locus of Native American Indians.

Using the polymerase chain reaction to amplify genomic DNA from hair roots, we have examined the mitochondrial aldehyde dehydrogenase (ALDH2) genotypes of 28 individuals from the South American Mapuche Indians. We have determined that individuals from this population previously reported to lack (ALDH2) activity do not show the presence of the inactive (ALDH2(2] allele frequently found in Orientals.

Adult↗
PubMed1990

Hemoglobin-acetaldehyde adducts in human volunteers following acute ethanol ingestion.

Rabbit antibodies against albumin-acetaldehyde adduct were used in an enzyme-linked immunosorbent assay to detect acetaldehyde-hemoglobin condensates from the blood of 12 volunteers following ingestion of 1.3 to 2.9 g of ethanol per kg body weight during 8 hr. Blood samples were drawn before drinking and between 2 to 46 hr after starting the drinking session. While there were no significant increases in blood acetaldehyde levels in these samples, acetaldehyde-hemoglobin adducts were significantly increased in the samples drawn after ethanol had been eliminated from the body. Administration of ethanol (0.1 g/kg) to an Oriental flusher resulted in an increase both in blood acetaldehyde and the hemoglobin-acetaldehyde adduct levels. These results suggest that acetaldehyde-hemoglobin condensates are formed in vivo following acute ethanol ingestion. Such condensates may be of value to mark alcohol consumption.

Acetaldehyde↗