Expression of the glutathione enzyme system of human colon mucosa by localisation, gender and age.

BACKGROUND: The glutathione S-transferases (GST) can metabolise endogenous and exogenous toxins and carcinogens by catalysing the conjugation of diverse electrophiles with reduced glutathione (GSH). Variations of GST enzyme activity could influence the susceptibility of developing cancers in certain areas of the gastrointestinal tract. AIMS: The expression of the components of the glutathione system in the colon was investigated with respect to age, gender and localisation. METHODS: Biopsies of macroscopically normal mucosa from both proximal and distal colon were collected from 208 patients (106 females, 102 males; mean age 61 years), who underwent colonoscopy for various clinical reasons. GSH content, total GST enzyme activity and the levels of the GST isoenzymes glutathione S-transferase P1 (GSTP1) and glutathione S-transferase M1 (GSTM1) were determined. RESULTS: GST enzyme activity, GSH and GSTP1 levels decreased significantly from proximal to distal colon (GST activity: 264 vs. 244 nmol/min/mg protein, p < 0.001, GSH content: 32 vs. 30 nmol/mg protein, p = 0.022 and GSTP1 levels: 2.25 vs. 2.10 mug/mg protein, p < 0.001). In female patients there was a significant stepwise increase of GST-activities and GSTP1 levels from the age of under 50 years to over 70 years. Oral sex hormone substitution among female patients between 50 and 70 years suppressed GST-activities and GSTP1 content. CONCLUSIONS: The GSH-system in the colonic mucosa is expressed at a lower level in the distal colon (sigma) than in the colon transversum; whether this small difference translates into variations of incidence of colorectal cancer remains to be seen. Females express higher enzyme levels as they grow older, while in males no significant age effects were found. Elderly females might be better equipped with protective GSH-enzymes in the colon than males and this could contribute to the lower incidence of colorectal carcinomas in females.

Antipyrine elimination and hepatic microsomal enzyme activity in patients with liver disease.

Induction of hepatic monooxygenases reflected by 7-ethoxycoumarin O-deethylase has been proposed to be associated with the initiation of liver damage. This study investigated a possible correlation between 7-ethoxycoumarin O-deethylase, reduced nicotinamide adenine dinucleotide phosphate cytochrome c reductase and benzypyrene hydroxylase activity in liver biopsy specimens of 31 patients with liver disease and antipyrine elimination, an in vivo parameter of hepatic monooxygenase activity. No correlation was found between the enzyme activities and antipyrine clearance or half-life. When microsomal enzyme activities were compared with the formation rate of 4-hydroxyantipyrine, 3-methylhydroxyantipyrine, and norantipyrine, a correlation was found only between benzo[alpha]pyrene hydroxylase and 3-methylhydroxyantipyrine (r = 0.89; p less than 0.0005). There was also a correlation between 7-ethoxycoumarin O-deethylase and reduced nicotinamide adenine dinucleotide phosphate cytochrome c reductase (0.56; p less than 0.05). Our data suggest that antipyrine elimination is not related to 7-ethoxycoumarin O-deethylase activity in liver disease. However, the formation rate of antipyrine metabolites, rather than antipyrine half-life and clearance, may correlate with the activity of certain microsomal enzymes.

Interactions and non-interactions with ranitidine.

At present, there are two H2-receptor antagonists available for the treatment of peptic ulcer disease - cimetidine and ranitidine. Cimetidine is well known to interact with a number of concurrently administered drugs. Like cimetidine, ranitidine binds to cytochrome P-450 in the liver where it appears to exert an inhibitory effect, but to a lesser extent than cimetidine. Both H2-receptor antagonists may also reduce hepatic blood flow. Several drugs which are known to interact with cimetidine have been found not to interact significantly with ranitidine, including propranolol, lignocaine, phenytoin and diazepam. However, significant pharmacokinetic interactions between ranitidine and several other drugs have been established. These interactions may be attributed variously to an effect of ranitidine on hepatic metabolism or to an effect on the absorption of concomitantly administered drugs. For example, the bioavailability of midazolam is significantly increased due to the influence of ranitidine on gastric pH and thus on absorption of midazolam, leading to an increased soporific effect of this benzodiazepine; an effect of ranitidine on oxidative liver metabolism also appears to be a contributory factor in this interaction. Conversely, ranitidine distinctly reduced protein-bound cobalamin absorption from a mean of 7.66% prior to ranitidine administration to 0.84% during treatment with ranitidine 300 mg daily. A significant pharmacokinetic interaction has also been demonstrated between ranitidine and procainamide: the AUC of procainamide increased and the renal clearance fell significantly from a mean of 378 to 309 ml/min with ranitidine co-administration. However, this interaction is due to a different mechanism. In this case, ranitidine appears to compete with procainamide for the common renal proximal tubular secretion site. The reported interactions of ranitidine with warfarin, metoprolol, nifedipine, theophylline and fentanyl appear to be due to inhibition of cytochrome P-450. In a clinical study, warfarin clearance was significantly reduced from 66.7 to 48.7 ml/min by ranitidine, and by cimetidine to 42.9 ml/min. Similarly, the elimination half-lives of metoprolol and nifedipine were distinctly prolonged and the AUCs significantly increased by ranitidine. However, the latter pharmacokinetic interactions appear unlikely to be of clinical significance since the clinical effects of metoprolol and nifedipine were unaffected by ranitidine treatment. In therapeutic concentrations, ranitidine inhibited the disappearance of fentanyl from an in vitro microsomal preparation, indicating that it inhibits microsomal drug metabolism.(ABSTRACT TRUNCATED AT 400 WORDS)

Biotransformation of xenobiotics in human intestinal mucosa.

Drug-metabolizing enzymes, especially monooxygenases, play a major role in biotransformation and detoxification of many foreign compounds including environmental carcinogens. Although largely localized in the liver they are also found in the small intestine, which is the portal of entry of dietary toxins. Therefore cytochrome P-450 content as well as monooxygenase (7-ethoxycoumarin O-deethylase) and NADPH-cytochrome c reductase activities were determined in surgical specimens of the human small intestine and in jejunal biopsy material obtained from patients by use of a hydraulic biopsy instrument. Microsomes were prepared from surgical material; these ranged in P-450 content from 30 to 120 pmole/mg protein and in monooxygenase activity from 60 to 110 pmole/min-mg protein. In the 20,000g supernatant of the homogenized biopsy material, monooxygenase activity was undetectable in patients who had total villous atrophy, and low enzyme rates were found when the mucosa showed a partial villous atrophy. The mucosal monooxygenase activity of patients with normal jejunal histology and steatorrhea was significantly higher than in mucosa with villous atrophy but was only half of that observed in normal controls. These eight control patients had normal histology and no malassimilation. Our results suggest that monooxygenase activity in the human small intestine is dependent on the morphological integrity of the mucosa and that in normal mucosa the enzyme rates are reduced when malassimilation is present.

[Anti-inflammatory effects of tea-flavonoids]. / Anti-inflammatorische Wirkungen der Tee-Flavonoide.

Tea flavonoids belong to the large group of polyphenols and display antioxidative, anti-inflammatory and anti-neoplastic activities. These phytochemicals are xenobiotics and are synthesized by tea plants such as Camellia sinensis and Camomilla recucita. These botanicals exhibit in vivo activities similar to that of biologicals which are widely used for chronic inflammatory diseases (rheumatoid arthritis, chronic inflammatory bowel disease). Epigallocathechin gallate and apigenin from these plants inhibit cytokines, chemokines and activated immune cells in vivo and in vitro. Clinical disorders with induced inflammatory pathways could benefit from flavonoid treatment. Dietary supplementation with specific tea-flavonoids could be used for Crohn's disease, ulcerative colitis and irritable bowel syndrome. Suppression of cytokine production could ultimately lead to inhibition of carcinogenesis. This mechanism could explain why flavonoids are effective in the prevention of intestinal neoplasia. This innovative new form of therapy should be tested in controlled, randomized clinical studies.

Effect of chlormethiazole on the hepatic monooxygenase enzyme system.

Ethanol abuse has been shown to induce hepatic monooxygenase activity. In order to study the effect of chlormethiazole on the hepatic monooxygenase enzyme system, the O-deethylation of 7-ethoxycoumarin was studied. Chlormethiazole was found to inhibit ethanol-induced monooxygenase activity.

[Enzyme induction of the liver caused by chronic alcoholism as risk factor in hepatotoxicity]. / Enzyminduktion der Leber durch chronischen Alkoholismus als Risikofaktor der Hepatotoxizität.

Abuse of ethanol has shown to induce the drug-metabolizing enzyme activity of the liver in rats and in humans. Therefore, we studied cytochrome P-450 dependent monooxygenase and conjugating enzyme activity in needle liver biopsy specimens of patients using the following substrates and enzyme assays: 7-ethoxycoumarin O-deethylase (EOD), p-nitroanisol O-demethylase (PNA), NADPH-cytochrome c reductase, 1-naphtol glucuronyltransferase (NGT). Among alcoholics induction of EOD, PNA and NGT was only found in patients with active alcoholic liver damage (elevated transaminases and necrosis of the liver cells). The other groups had either normal enzyme activity (abstinent alcoholics, residual alcoholic liver damage) or low activity (liver cirrhosis, cholestatic liver disease). Surprisingly, nonabstinent alcoholics with normal liver histology did not reveal enzyme induction. Enzyme induction was dependent on time of abstinence. Within 20 days of abstinence the induction tapered off concomitantly with the resolution of active liver injury. The hyperactive ethanol-induced enzyme system could produce toxic oxygen radicals leading to liver injury and also toxify drugs (paracetamol, halogenated hydrocarbons, INH). Induction of hepatic monooxygenase activity by ethanol, although originally an adaptive response, might therefore increase the risk of hepatotoxicity of certain drugs.

[Foreign substance-degrading enzyme system of the human liver. Modification by alcohol, other exogenous factors and liver diseases]. / Fremdstoff-abbauendes Enzym-System der menschlichen Leber. Beeinflussung durch Alkohol, andere exogene Faktoren und Lebererkrankungen.

Ethanol was found to be capable to stimulate the microsomal xenobiotic-metabolizing enzyme system of human liver. However, this effect was seen only in cases of alcoholic liver damage (fatty liver, alcoholic hepatitis). Alcoholics without alcoholic liver injury had enzyme activities comparable to control patients, who had no liver disease. On ethanol abstinence the enzyme stimulation was reversible within 20 days. Stimulation of xenobiotic-metabolizing enzyme activity in alcoholic liver disease seems to be related to ethanol induced toxicity. The highest enzyme activities were observed in patients on enzyme inducing drugs (2- to 6 fold increase), whereas in alcoholic liver disease enzyme activities were doubled. These results suggest that the stimulation of the microsomal enzyme system caused by ethanol is different from the enzyme induction seen on inducing drugs.

[Small bowel biopsy as a cause of pseudomonas aeruginosa septicemia in a patient with intestinal lymphoma? (author's transl)]. / Dünndarmbiopsie als Ursache einer Pseudomonas-aeruginosa-Sepsis bei einem Patienten mit intestinalem Lymphom?

A patient with intestinal lymphoma developed a gram-negative septicemia 48 hours following a peroral biopsy of the small intestine. The bacteriological examination of the instrument proved the same bacteria (Pseudomonas aeruginosa) which was the cause of septicemia. On the basis of our observation and of other reports it seems reasonable besides gassterilization or effective disinfection of the instruments to carry out cultural examinations of the instrument before and following endoscopic and bioptic investigations of patients with impaired resistance; it would then be possible to start an appropriate antibiotic treatment in case of a septic complication.

Inducing efficacy of ethanol on hepatic drug metabolizing enzymes in patients.

In liver biopsy material of eighty-nine patients with suspected liver disease the drug-metabolizing function was investigated. The capacity of the liver to oxidatively metabolize drugs was assessed by determination of cytochrome P-450 dependent monooxygenase activity in vitro. The biotransformational function of these microsomal enzymes was tested with compounds representing the activity of oxidative drug metabolism (7-ethoxycoumarin, p-nitroanisol and cytochrome c). From the eight-nine patients sixty-one had various liver diseases not related to ethanol and twenty-eight abused ethanol. When both groups were matched for age, sex, smoking, treatment with sedatives, drugs and degree of liver damage the alcoholic group had significantly higher activities of 7-ethoxycoumarin O-deethylase (EOD: 76.9 +/- 31.1 pmol min-1 mg-1 protein, mean +/- SD) than the non-alcoholic liver disease group (42.7 +/- 14.1). The inducing effect of ethanol was most striking on the EOD activity, less for the O-demethylation of p-nitroanisol (PNA) and not present for the NADPH-cytochrome c reductase. The induced patients were analysed in detail to find out which factors were responsible for the observed scatter of enzyme activities within the alcoholic group. Alcoholics with fatty liver (n = 7) had the highest EOD activities (108.9 +/- 25.0), patients with alcoholic hepatitis (n = 10) had significantly less activity (66.0 +/- 1.9) than the former group. However, alcoholics without liver damage (n = 6) had activities not significantly different (46.0 +/- 15.8) from controls (39.4 +/- 9.1). These subgroups among the alcoholics were comparable in terms of sex, age, smoking and drinking habits.(ABSTRACT TRUNCATED AT 250 WORDS)

Distribution of glutathione and its related enzymes in small intestinal mucosa of rats.

Glutathione (GSH) concentration of whole mucosa was 2.96 +/- 0.26 (mean +/- SEM) mumol/g wet weight in all segments: however the tip cell layer contained significantly less GSH than the lower mucosal cells. GSH S-transferase (GSH-T) activities displayed a striking gradient with highest values in the duodenum and lowest in the terminal ileum. gamma-glutamyl transpeptidase (GGT) activities were also highest in the proximal segment but lowest in the fifth segment among eight divided segments. Along the villus/crypt axis GGT and to a lesser degree GSH-T were also polarized with highest activities in the villus tip cell region. GSH peroxidase (GSH-Px) and glutathione reductase (GSSG-R) had an even distribution along the intestinal tube and among the mucosal cell populations. This distinct pattern of distribution suggests a functional adaptation of GSH and its related enzymes; GSH-T might be important for detoxification of exogenous luminal compounds which enter the body in the upper intestinal segments while GSH-Px might be responsible for peroxidation of endogenously produced compounds.

Cyclophosphamide-induced remission in Weber-Christian panniculitis.

A patient with Weber-Christian panniculitis is described in this report in which treatment with prednisone and hydroxychloroquine caused no improvement of the disease, and even led to a worsening of the symptoms. In contrast, administration of oral cyclophosphamide led to a rapid remission of the disease. As Weber-Christian disease has no known aetiology and no specific treatment has been established, the successful therapy with the cytostatic drug cyclophosphamide may shed light on the pathogenesis of Weber-Christian panniculitis.

[Differential diagnosis in fever of unknown origin: significance of concomitant clinical symptoms]. / Differentialdiagnose bei bisher ungeklärtem Fieber: Bedeutung klinischer Begleitsymptome.

Between 1978 and 1984, 169 patients were admitted to the hospital for fever of unknown origin which was repeatedly above 38.3 degrees C. After a retrospective analysis of their records the patients were divided into two groups on the basis of the following new criteria. The first group (74 patients) was described as having "monosymptomatic fever", i.e. fever without any other physical signs, whereas the second group (95 patients) had "polysymptomatic fever", i.e. fever with additional physical signs. In 56 patients (76%) of the monosymptomatic group fever had lasted longer than 3 weeks prior to admission. In 86% of these patients case history, physical examination, microbiological tests, serological tests for microorganisms and outoimune antibodies, and microscopic inspections of tissue and/or bone marrow led to a diagnosis. Malignancies, factitious fever and fever of unknown origin were found only in this group. The patients with malignancies were generally older than the rest of the patients (p less than 0.05), and eight of ten patients suffering from connective tissue diseases also had monosymptomatic fever. The incidence of infections in this group was 42% (31 cases), in contrast to 88% (84 cases) in the polysymptomatic group (p less than 0.05). Whereas the latter had significantly more bacterial infections (p less than 0.05), viral infections prevailed in the monosymptomatic group (p less than 0.05). Thus, the etiology of polysymptomatic fever distinctly differed from that of monosymptomatic fever. Since the frequency distribution of etiologies in the monosymptomatic group corresponded to that of the cases of fever of unknown origin in the literature, differentiation into monosymptomatic and polysymptomatic fever might be helpful in determining further diagnostic workup of patients with fever of unknown origin.

Glutathione and its related enzymes in the small intestinal mucosa of rats: effects of starvation and diet.

Starvation for 24 h causes a striking fall in glutathione content from 3.19 +/- 0.27 to 1.88 +/- 0.14 (X +/- SEM) mumol/g tissue and of GGT activity from 31.75 +/- 4.17 to 19.49 +/- 3.13 (X +/- SEM) nmol/min/mg protein in the homogenate from whole mucosa of the upper small intestinal segments. This was associated with a significant increase in GSH-Px activity and the content of lipid peroxides (measured by the thiobarbituric assay). On semi-synthetic iron-supplemented diet the activities of GSH-T and GGT were significantly decreased as compared with crude diet. On semisynthetic iron-depleted diet GSH-T and GGT activities were further depressed, but this was accompanied with an additional depression of GSH, glutathione reductase (GSSG-R), and glutathione peroxidase (GSH-Px) activities and lipid peroxide concentrations. Food deprivation significantly lowers the mucosal GSH-content and could lead to a destabilization of this system presumably by increased oxidative stress. As compared to normal "crude" diet, semisynthetic diets and oral iron depletion have been shown to cause a depression of the intestinal GSH system. As a consequence of these effects, the resistance of the small intestinal mucosa toward exogeneous dietary toxins might be reduced.

[Benign symmetrical lipomatosis with polyneuropathy and mental performance deficits]. / Lipomatosis symmetrica benigna mit Polyneuropathie und Hirnleistungsdefiziten.

Lipomatosis symmetrica benigna is a rare condition, usually found in association with the complications of chronic alcoholism. A case is reported which showed the typical clinical picture, and diagnosis and therapy will are discussed.

Effects of semisynthetic diets on xenobiotic metabolizing enzyme activity and morphology of small intestinal mucosa in humans.

We studied the effects of semisynthetic (elemental) diets on the function and morphology of the human small intestine. The enzymatic capacity of the intestinal mucosa to metabolize lipophilic xenobiotics was investigated using jejunal biopsy specimens from 15 normal subjects who were on an isocaloric, nutritionally balanced semisynthetic diet for 7 days and thereafter on a normal home diet. Each subject underwent biopsy twice: on day 7 of semisynthetic diet and again on home diet 2-6 wk later. The jejunal mucosal tissue was examined by histologic morphometry and stereomicroscopy. Moreover, 25-50 mg of the biopsy material was homogenized and the following enzyme activities were determined in 20,000 g supernatant: for cytochrome P450-dependent monooxygenase activity with 7-ethoxycoumarin O-deethylase (EOD) and with nicotinamide adenine dinucleotide phosphate (NADPH)-cytochrome c reductase and for conjugation activity with 1-naphthol glucuronyltransferase (NGT). The NGT and reductase activities were unchanged by the dietary alterations. However, the EOD activity was significantly depressed on semisynthetic diet and rose to control range on home diet (from 5.3 +/- 2.5 to 12.4 +/- 8.6 pmol/min X 10 mg wet wt). Male subjects had significantly higher EOD activities than female subjects on semisynthetic diet (6.6 +/- 2.3 vs. 3.2 +/- 0.9) as well as on home diet (16.3 +/- 9.0 vs. 6.4 +/- 3.0). Semisynthetic diet also reduced the jejunal villous height significantly when compared with home diet (408 +/- 49 vs. 373 +/- 44 micron). Therefore, on semisynthetic diet the toxicity of dietary xenobiotics that are inactivated by the intestinal mucosa may be increased.

Isolation of human hepatic microsomes and their inhibition by cimetidine and ranitidine.

Human hepatic microsomes were isolated from wedge biopsies of the liver from 13 patients undergoing abdominal surgery. Ultrasonic homogenisation was used to increase the yield of microsomal monooxygenase activity (7-ethoxycoumarin O-deethylase, NADPH-cytochrome c reductase), resulting in a 30% higher total enzyme activity per g liver than preparation by other techniques. In 4 individual microsomal preparations the influence of cimetidine and ranitidine on Michaelis-Menten kinetics of O-deethylation and of reductase activity were studied. Without the H2-receptor blocking drugs, enzyme kinetics of O-deethylation with a Km of 51.0 +/- 16.4 microM (n = 3) were obtained using Lineweaver-Burke plots. Both, cimetidine and ranitidine inhibited the O-deethylation; cimetidine had a five-fold higher inhibitory affinity (Ki 1.01 and 3.94 mM) to the monooxygenase than ranitidine (Ki 4.96 and 17.70 mM) in the uninduced liver. However, in liver from a patient with induced enzyme activity (Km = 478.0 microM), the Ki of ranitidine was similar to that of cimetidine (Ki ran 3.57 versus Ki cim 2.49 mM). The reductase activity was not inhibited by ranitidine and only marginally so by cimetidine. The results suggest that in human hepatic microsomes oxidative drug metabolism is inhibited by both H2-receptor antagonists. However, the inhibitory potency of the compounds seems to depend on the individual isozyme pattern of the hepatic microsomes. Thus, while cimetidine is an relatively nonspecific enzyme inhibitor, ranitidine might more selectively inhibit induced drug metabolizing enzymes.

Effect of rifampicin treatment on hepatic drug metabolism and serum bile acids in patients with primary biliary cirrhosis.

Six patients with primary biliary cirrhosis (PBC) were treated with a daily oral dose of 600 mg rifampicin for 2 weeks to induce the hepatic metabolism of drugs and bile acids. On rifampicin 5 of 6 patients experienced a pronounced decrease of their pruritus. In all patients the oxidative cytochrome P-450 dependent drug metabolism was induced as shown by an increase of antipyrine-clearance from 36.3 +/- 8.8 to 80.6 +/- 20.1 ml/min and an enhanced urinary excretion of 6-beta-hydroxycortisol from 454 +/- 1.99 to 1607 +/- 362 micrograms/24 h. Furthermore, in all 6 patients the serum alkaline phosphatase declined. In the 3 cholestatic patients (bilirubin greater than 1.0 mg/dl) the serum concentration of total and conjugated bile acids was strikingly reduced. Thus, rifampicin is an inducer of hepatic metabolism in PBC-patients, ameliorates the pruritus and can lower serum concentrations of alkaline phosphatase and bile acids.