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Biomedical subjects

W H Peters

Publications and source records attributed to W H Peters.

At least 37 records · Page 2Linked to original sources
PubMed2000

Plasma thiol status in preeclampsia.

OBJECTIVE: To measure plasma thiol levels in women with normal pregnancies, women with preeclampsia, and nonpregnant controls to define plasma thiol's effect on glutathione homeostasis and pathophysiology of preeclampsia. METHODS: Total plasma cysteine, gamma-glutamylcysteine, homocysteine, cysteinylglycine, and glutathione levels were measured in ten nonpregnant women, ten women with normotensive pregnancies, and 20 women with preeclampsia at delivery. RESULTS: Median total plasma levels of all thiols in normotensive pregnant women were significantly lower than in nonpregnant women. Median total plasma cysteine and homocysteine levels in women with preeclampsia were significantly higher compared with pregnant controls (254 versus 190 micromol/L, P < .001; and 13.3 versus 8.4 micromol/L, P < .02, respectively), whereas glutathione levels were significantly lower in women with preeclampsia compared with those in pregnant controls (5.1 versus 6.3 micromol/L, P < .05). CONCLUSION: In women with preeclampsia, homocysteine and cysteine levels, which are lowered in normotensive pregnancy, were comparable to levels in nonpregnant women, whereas glutathione levels were lower. Those results suggest that in women with preeclampsia, glutathione use is higher or its synthesis is disturbed. Therefore, glutathione might affect pathophysiology of preeclampsia.

Adult↗
PubMed2000

Association of human liver bilirubin UDP-glucuronyltransferase activity with a polymorphism in the promoter region of the UGT1A1 gene.

BACKGROUND/AIMS: Gilbert's syndrome is a benign form of a deficiency in bilirubin glucuronidation. It is associated with a homozygous polymorphism, A(TA)7TAA instead of A(TA)6TAA, in the TATA-box of the promoter region of the bilirubin UDP-glucuronyltransferase gene. In this study the correlation between this promoter region polymorphism and in vitro human liver bilirubin UDP-glucuronyltransferase enzyme activity was investigated. METHODS: Liver samples from organ transplant donors n=39) and two known Gilbert's syndrome patients were used for measuring bilirubin UDP-glucuronyltransferase enzyme activity and for isolation of DNA followed by detection of the promoter region polymorphism by polymerase chain reaction. Genotypes were assigned as follows; 6/6: homozygous for the A(TA)6TAA-allele, 7/7: homozygous for the A(TA)7TAA-allele, and 6/7: heterozygous with one of each alleles. RESULTS: Seventeen out of 39 subjects (44%) had the homozygous 6/6 genotype, 18 subjects (46%) had the heterozygous 6/7 genotype, whereas four individuals (10%) and the two individuals with Gilbert's syndrome had the 7/7 genotype correlated with Gilbert's syndrome. This resulted in an allele frequency of 0.33 for the A(TA)7TAA-allele. The median bilirubin UDP-glucuronyltransferase enzyme activity of the 17 subjects with the 6/6 genotype (1565 nmol/g liver/h) was significantly higher than the activity of the 18 subjects with the 6/7 genotype (985 nmol/g liver/h; p<0.05) and the six individuals with the 7/7 genotype (749 nmol/g liver/h; p<0.005). No significant differences in enzyme activity were found between the 6/7 and the 7/7 genotype groups. CONCLUSIONS: The results indicate a close association between the promoter region genotype and the expression of hepatic bilirubin UDP-glucuronyltransferase enzyme activity. Subjects who have a 7/7 genotype have the lowest enzyme activity, whereas subjects with the heterozygous 6/7 genotype have an intermediate enzyme activity.

Alleles↗
PubMed2000

Antral glutathione concentration and glutathione S-transferase activity in patients with and without Helicobacter pylori.

Previously we demonstrated an inverse relation between cancer of the gastrointestinal tract and glutathione S-transferase activity of the gastrointestinal mucosa. Chronic infection with H. pylori has been associated with an increased risk of gastric cancer. The aim of this study was to investigate the levels of glutathione and glutathione S-transferase activity in H. pylori-infected and noninfected antral mucosa. Glutathione and glutathione S-transferases were measured in antral biopsies of patients with nonulcer dyspepsia without H. pylori infection (A), with prior H. pylori infection who became H. pylori negative after eradication therapy (B) and with proven H. pylori infection (C). Glutathione concentration and glutathione S-transferase activity in group A were 31.0 (range 6.0-59.6) nmol/mg protein and 810 (range 165-1312) nmol/min/mg protein, in group B 27.0 (range 5.0-53.8) nmol/mg protein and 745 (range 403-1199) nmol/min/mg protein, and in group C 18.5 (range 1.6-55.8) nmol/mg protein and 572 (range 144-1047) nmol/min/mg protein, respectively. The glutathione and glutathione S-transferase values were significantly lower in patients infected with H. pylori than in patients who were H. pylori negative.

Adult↗
PubMed2000

The effect of unfiltered coffee on potential biomarkers for colonic cancer risk in healthy volunteers: a randomized trial.

BACKGROUND: Epidemiologic studies suggest that coffee use might protect against colorectal cancer. Inconsistencies as to the effect of coffee use and colorectal cancer between epidemiologic studies might be related to the type of coffee brew. OBJECTIVE: We studied the effect of unfiltered coffee consumption on putative biomarkers for colonic cancer risk. DESIGN: A total of 64 healthy volunteers (31 men and 33 women), with a mean age of 43 +/- 11 years were randomly assigned to two groups in a crossover design, with two intervention periods of 2 weeks separated by a washout period of 8 weeks. Treatments were 1 L of cafetière (French press) coffee daily or no coffee. At the end of each intervention period, fasting blood samples, colorectal biopsies and 48 h faeces were collected. RESULTS: No effect of coffee on colorectal cell proliferation, assayed by estimating the Proliferating Cell Nuclear Antigen labelling index, was seen. Additionally, no effects were seen on the concentrations of faecal soluble bile acids and colorectal mucosal glutathione S-transferase activity. However, unfiltered coffee significantly increased the glutathione content in the colorectal mucosa by 8% and in plasma by 15%. Other aminothiols in plasma also increased on coffee. CONCLUSION: Unfiltered coffee does not influence the colorectal mucosal proliferation rate, but might increase the detoxification capacity and anti-mutagenic properties in the colorectal mucosa through an increase in glutathione concentration. Whether this effect indeed contributes to a lower colon cancer risk remains to be established.

Adult↗
PubMed2000

Low levels of colonic glutathione S-transferase in patients with X-linked agammaglobulinaemia.

BACKGROUND: Patients with X-linked agammaglobulinaemia, a primary immunodeficiency disorder, suffer from recurrent infections of the respiratory and intestinal tract. Rapidly progressive colorectal cancer was diagnosed in three unrelated young adults with X-linked agammaglobulinaemia. This finding implies a 30-fold increase of risk for this cancer in this patient group. Glutathione S-transferases are a family of biotransformation enzymes involved in the detoxification of cytotoxic and carcinogenic compounds, that may function in the prevention of carcinogenesis. We investigated the possible role of the glutathione S-transferase enzyme system in the apparently increased colorectal cancer risk in X-linked agammaglobulinaemia patients. MATERIALS AND METHODS: We analysed the glutathione levels and the glutathione S-transferase enzyme activity and iso-enzyme composition in normal colonic biopsies of eight X-linked agammaglobulinaemia patients, 25 patients with a recent history of colonic adenomas and 10 healthy volunteers. RESULTS: X-linked agammaglobulinaemia patients had significantly lower glutathione S-transferase enzyme activities at all sites in the normal colonic mucosa as compared to adenoma patients. In X-linked agammaglobulinaemia patients the rectal glutathione S-transferase enzyme activity was lower than in the proximal colon and significantly lower as compared to controls. CONCLUSION: This lower glutathione S-transferase enzyme activity might play a role in the apparently increased colorectal cancer risk in X-linked agammaglobulinaemia patients, assuming that detoxification of carcinogenic compounds plays a role in the aetiology of colon cancer of these patients.

Adenoma↗
PubMed2000

Deficient detoxifying capacity in the pathophysiology of preeclampsia.

An imbalance between oxidative stress and maternal detoxification or antioxidant capacity may explain the symptoms of preeclampsia and the haemolysis-elevated liver enzymes-low platelets (HELLP) syndrome. Oxidative stress is known to induce damage of the endothelium, which is one of the pathophysiological features of preeclampsia and the HELLP syndrome. Administration of N-acetylcysteine, an antioxidant itself and a precursor of the endogenous antioxidant glutathione, might stabilize or even partly recover the process of endothelial damage and may lead to prolongation of pregnancy.

Acetylcysteine↗
PubMed2000

Plasma protein carbonyls in nonpregnant, healthy pregnant and preeclamptic women.

Increased reactive oxygen species (ROS) and lipid peroxidation may be implicated in the pathogenesis of preeclampsia by causing cell (membrane) damage and impaired endothelial function. Carbonyl derivatives of proteins, or protein carbonyls, may be sensitive biomarkers of ROS-mediated damage. The aim of the study was to compare levels of protein carbonyls in plasma of preeclamptic, healthy pregnant and healthy nonpregnant women. Plasma protein carbonyls were measured in 47 preeclamptic, 45 healthy pregnant and 22 healthy nonpregnant women by using a sensitive ELISA-method. ANOVA, the unpaired t-test and Pearson's correlation were used for statistical analysis. Preeclamptic women had significantly higher plasma protein carbonyl levels than healthy pregnant women (P < 0.0001). Healthy pregnant women showed significantly higher protein carbonyl levels (P < 0.001) as compared to nonpregnant controls. The higher levels of protein carbonyls as compared to nonpregnant controls suggest that increased oxygen free radical damage occurs in normal pregnancy and to a much higher extent in preeclampsia.

Adult↗
PubMed2000

Methylenetetrahydrofolate reductase polymorphisms in preeclampsia and the HELLP syndrome.

OBJECTIVE: To investigate the prevalence of the 677 (C --> T) and 1298 (A --> C) polymorphisms in the methylenetetrahydrofolate reductase (MTHFR) gene in our preeclamptic population. For a summary estimation of the risk of the 677 (C --> T) polymorphism for preeclampsia, we also performed a meta-analysis on four previously published case-control studies to which our results were added. METHODS: Genotypes were analyzed by polymerase chain reaction followed by restriction enzyme analysis. The results of 176 nonpregnant women, previously hospitalized for preeclampsia in a tertiary care center, were compared with 403 Dutch population-based controls. Results were statistically analyzed with a chi-square test. MEAN OUTCOME MEASURES: The incidence of the 677 (C --> T) and 1298 (A --> C) polymorphisms in the MTHFR gene. RESULTS: The incidence of both MTHFR missense polymorphisms was not significantly different between cases and controls. We found an odds ratio (OR) of 1.5 [95% confidence interval (CI) 0.8-2.6, p = 0.17] and an OR of 1.0 (95% CI 0.6-1.9, p = 0.23) for the 677 (C --> T) and the 1298 (A --> C) polymorphism, respectively, in cases comparing the prevalence of the homozygous genotype versus the other two genotypes. The meta-analysis resulted in a significant OR of 2.0 (95% CI 1.4-2.9). CONCLUSIONS: In contrast to four previous studies, we were neither able to confirm an increased risk for preeclampsia to the 677 (C --> T) polymorphism nor did we find an increased risk for preeclampsia to the 1298 (A --> C) polymorphism. From the meta-analysis, however, we conclude that it cannot be ruled out that the homozygous 677TT genotype is a modest but significant risk factor for preeclampsia.

Case-Control Studies↗
PubMed2000

Polymorphisms in biotransformation enzymes and the risk for recurrent early pregnancy loss.

An imbalance between phase I drug metabolizing enzymes and phase II detoxification enzymes may contribute to the development of pre-eclampsia. Polymorphic variants in the phase I enzyme, cytochrome P450 genes may lead to increased toxification, whereas polymorphisms in the phase II enzyme, glutathione S-transferase genes may result in impaired detoxification. Most abundant in placenta and decidua is glutathione S-transferase P1-1, which may therefore be of particular importance in reproduction. We studied the frequencies of polymorphic variants in those enzymes in 187 women with recurrent early pregnancy loss and in 109 women with an uncomplicated obstetric history. DNA was extracted and subsequently polymerase chain reaction based genotyping assays were used. chi(2)-Analysis and Fisher's exact test were used for statistical evaluation. The glutathione S-transferase P1b-1b genotype was found significantly more often in women with recurrent early pregnancy loss than in controls (12% versus 5%, P = 0.03), in particular in those who consumed coffee (P = 0.02) or smoked cigarettes (P = 0.04). Polymorphisms in other glutathione S-transferase and cytochrome P450 genes occurred equally frequently in cases and controls. In conclusion, the occurrence of the glutathione S-transferase P1b-1b genotype, leading to lower glutathione S-transferase Pi enzyme activity and consequently to impaired placental detoxification, may represent a risk factor for recurrent early pregnancy loss.

Abortion, Habitual↗
PubMed2000

Expression of glutathione S-transferase alpha, P1-1 and T1-1 in the human gastrointestinal tract.

Glutathione S-transferases (GSTs) form a family of enzymes, which play an important role in the prevention of cancer by detoxifying numerous potentially carcinogenic compounds. GSTs catalyze the conjugation of glutathione to such harmful molecules, and enable their secretion. Human GSTs can be divided into five main classes. The theta class of isoenzymes was only recently identified and limited (immunohistochemical) data on these enzymes are available. In the present study, paraffin-embedded sections of different gastrointestinal tissues were analyzed immunohistochemically for GSTalpha, GSTP1-1 and GSTT1-1 expression using specific antibodies. GSTalpha, GSTP1-1 and GSTT1-1 were highly expressed in all gastrointestinal tissues examined, with a unique cellular distribution. GSTT1-1 is the first GST isoenzyme demonstrated in duodenal Paneth cells and glands of Brunner. The common expression of GSTalpha, GSTT1-1 and GSTP1-1 in many cell types along the human gastrointestinal tract suggests an important role in the protection against carcinogens and other xenobiotics.

Digestive System↗
PubMed2000

Urinary excretion of glutathione S transferases alpha and pi in patients with proteinuria: reflection of the site of tubular injury.

In patients with renal diseases, proteinuria is a major determinant of progressive renal failure, probably by causing tubular cell injury. Little is known on extent and site of tubular cell injury in patients with proteinuria. Glutathione S transferases (GST) are cytosolic enzymes. The alpha isoform is present only in proximal tubular cells, whereas the pi isoform is confined to distal tubular cells. We have studied the urinary excretion of both isoenzymes in 56 (38 male and 18 female) patients with glomerular diseases and proteinuria. The mean age was 45 +/- (SD) 16 years, the median creatinine clearance was 80 (range 27-159) ml/min, and the median albuminuria was 4.2 (range 0.7-16.9) g/10 mmol creatinine. The excretions of both GST alpha (median 35.9 ng/10 mmol creatinine) and GST pi (median 24.8 ng/10 mmol creatinine) were elevated as compared with control values (upper limits 10 and 12 ng/10 mmol creatinine, respectively). The urinary excretion of GST pi, but not that of GST alpha, was inversely correlated with the creatinine clearance. The highest levels of GST alpha were found in patients with a well-preserved renal function, whereas highest levels of GST pi were found in patients with renal failure. In a small number of patients we performed immunofluorescent studies of renal tissue. An increased urinary excretion of GST alpha correlated with brush border damage and decreased staining of proximal tubules for that isoenzyme. Our data suggest that in patients with proteinuria initial injury is apparent at the proximal tubules. Measurements of GST alpha and GST pi appear useful to study longitudinal timing and site of proteinuria-induced tubular cell injury.

Acetylglucosaminidase↗
PubMed2000

Plasma glutathione S-transferase pi 1-1 AND alpha 1-1 levels in patients with bladder cancer.

PURPOSE: Transitional cell carcinomas of the human bladder and many gastrointestinal tumors often contain high amounts of the detoxification enzyme glutathione S-transferase pi (GSTP1-1). Elevated levels of GSTP1-1 have been found in serum and plasma from patients with gastrointestinal, lung or head and neck cancer. GSTP1-1 and glutathione S-transferase alpha (GSTA1-1) have been reported to be increased in 10 of 15 patients (67%) with bladder cancer. We evaluate the role of GSTP1-1 and GSTA1-1 as plasma tumor markers in 50 patients with bladder cancer before and after treatment. MATERIALS AND METHODS: Blood from patients with bladder cancer was sampled in ethylenediaminetetraacetic acid tubes. Plasma GSTA1-1 and GSTP1-1 were measured using the sensitive and specific sandwich enzyme-linked immunosorbent assay. RESULTS: Respective plasma GSTA1-1 and GSTP1-1 levels were above the upper normal reference limit in 2 (4%) and 14 (28%) of the 50 patients with bladder cancer. No significant decrease in plasma GSTA1-1 or GSTP1-1 was noted in matched pairs of plasma samples collected before and after treatment. CONCLUSIONS: In contrast to earlier reports, only a limited number of patients with bladder cancer had increased plasma GSTA1-1 or GSTP1-1, which did not decrease after tumor resection. These findings argue against the use of GSTP1-1 or GSTA1-1 as plasma markers for bladder cancer.

Adult↗
PubMed2000

Effects of Helicobacter pylori infection on endocrine and exocrine mucosal functions in the upper gastrointestinal tract.

BACKGROUND: Helicobacter pylori infection affects the concentration of regulatory peptides such as gastrin, somatostatin and cholecystokinin and the concentration and activity of glutathione and glutathione S-transferases in the gastric mucosa. METHODS: Literature review. RESULTS: Although some of these peptides have been known since the beginning of this century, their action has changed since the discovery of H. pylori infection in 1983. Chronic infection with H. pylori might lead to an increased risk in developing gastric cancer. Glutathione S-transferases are involved in the cellular detoxification of xenobiotics and other toxic compounds. Since there is a close inverse relationship between the activity of glutathione S-transferase and incidence of malignancies in the gastrointestinal tract, the possible relation between H. pylori infection and activity of glutathione S-transferases in the gastric mucosa is discussed. CONCLUSION: The effect of H. pylori infection on regulatory peptides and glutathione/glutathione S-transferases might play a role in the development of neoplastic changes of the H. pylori-infected gastric mucosa.

Animals↗
PubMed1999

Polymorphic expression of the glutathione S-transferase P1 gene and its susceptibility to Barrett's esophagus and esophageal carcinoma.

Factors determining individual susceptibility to esophageal cancer or premalignant Barrett's epithelium are still largely unclear. An imbalance between phase I drug metabolism [e.g., cytochrome P450 (CYP)] and phase II detoxification [e.g., glutathione S-transferase (GST)] may contribute to the development of these diseases. Polymorphic variants in the CYP1A1 gene were described leading to increased levels of bioactive compounds, whereas polymorphisms in GST genes often resulted in impaired detoxification. We studied the frequencies of polymorphic variants in CYP1A1, GSTP1, GSTT1, and GSTM1 genes in 98 patients with Barrett's epithelium and 34 patients with esophageal cancer. The results were compared with those obtained from 247 healthy blood donors. DNA was extracted, and PCR-RFLP methods were used to detect genetic polymorphisms. Chi2 analysis, Spearman rank correlation, and Wilcoxon rank sum tests were used for statistical evaluation. Polymorphisms in CYP1A1, GSTM1, and GSTT1 occurred at an equal frequency in patients and controls. Occurrence of the polymorphic GSTP1b variant in the GSTP1 gene resulted in a significantly lower GST enzyme activity (P < 0.05), and GSTP1b was found significantly more often in patients with Barrett's epithelium (70%; P < 0.001) and patients with esophageal adenocarcinoma (76%; P = 0.005), as compared to healthy blood donors (41%). In conclusion, presence of the GSTP1b allele leads to lower GST enzyme activity levels and, consequently, impaired detoxification. This most important esophageal GST isoform may, therefore, contribute to the development of Barrett's epithelium and adenocarcinoma.

Adenocarcinoma↗
PubMed1999

Glutathione S-transferase isoenzymes in decidua and placenta of preeclamptic pregnancies.

OBJECTIVE: To investigate a possible involvement of glutathione S-transferases, major detoxificating enzymes, in the pathophysiology of preeclampsia. METHODS: Levels of glutathione S-transferase isoforms and enzyme activity were assessed in placental and decidual tissues in 22 preeclamptic and 21 normotensive women. Measured values were analyzed statistically using the Mann-Whitney U test for comparison between groups, and the signed-rank test for comparison within groups. RESULTS: Glutathione S-transferase pi is the main glutathione S-transferase isoform in normal placental and decidual tissue. Lower median placental and decidual glutathione S-transferase pi levels were found in preeclamptic women compared with controls: 1268 (range: 524-3925) and 2185 (range: 503-6578), P = .05, for placenta; 1543 (range: 681-2967) and 2169 (range: 893-3929), P = .02, for decidua. The total amount of glutathione S-transferases in control and preeclamptic pregnancies was higher in decidua than in placenta. CONCLUSION: Reduced levels of glutathione S-transferase class pi in preeclampsia might indicate a decreased capacity of the glutathione/glutathione S-transferase detoxification system. A higher total amount of glutathione S-transferases in decidual tissue might point to a more pronounced protective role of decidua compared with placenta.

Adult↗
PubMed1999

Glutathione and glutathione-related enzymes in reproduction. A review.

Glutathione and glutathione-related enzymes are pivotal for the normal functioning of several important biological processes in humans. Glutathione and glutathione-related enzymes are involved in the metabolism and detoxification of cytotoxic and carcinogenic compounds as well as reactive oxygen species. The role of reactive oxygen species in reproduction was the subject of many investigations, and there is compelling evidence for the involvement of these species in the physiology and pathology of both male and female reproductive systems. The glutathione/glutathione-related enzyme system was extensively studied in gynaecological oncology, but to a lesser extent in other topics related to reproduction. In this paper a review is provided on the glutathione/glutathione-related enzyme system in reproduction. Attention is given to its role as a detoxicating system, and as an early marker for disease.

Female↗
PubMed1999

Glutathione S-transferase Alpha 1-1 and aminotransferases in umbilical cord blood.

Recent data suggest that levels of glutathione S-transferase Alpha 1-1 in umbilical cord plasma may be a good indicator of neonatal hepatocellular integrity. In order to fully understand the significance of this new marker we compared the values of glutathione S-transferase Alpha 1-1 (GSTA1-1) with that of the well known liver function markers alanine aminotransferase (ALT) and aspartate aminotransferase (AST) in arterial and corresponding venous umbilical cord blood of 93 patients. In addition, in 49 of these patients maternal venous blood was also studied. Both arterial and venous umbilical cord GSTA1-1 and AST levels were significantly higher than corresponding maternal venous levels, whereas ALT levels were not. Arterial umbilical cord GSTA1-1 correlated significantly with the corresponding AST and ALT levels (R = 0.46, P < 0.0001 and R = 0.41, P < 0.0001, respectively). Arterial umbilical cord AST correlated significantly with corresponding ALT levels (R = 0.58, P < 0.0001). Arterial umbilical cord plasma GSTA1-1 levels were significantly lower in the cesarean delivery group as compared to the vaginal birth group, whereas no difference was noted for AST or ALT. Arterial umbilical cord AST and GSTA1-1 levels correlated significantly with base deficit (R = 0.29, P = 0.005; R = 0.29, P = 0.005, respectively), whereas ALT did not (R = 0.06, P = 0.54). Arterial umbilical cord AST, ALT, and GSTA1-1 levels correlated significantly with birthweight. In conclusion, GSTA1-1 levels as assessed in neonatal umbilical cord blood, being unrelated to maternal levels, seem to be a more sensitive marker for early neonatal hepatocellular integrity as compared to ALT or AST and even might detect impaired hepatocellular integrity due to the vaginal birth process. Umbilical cord GSTA1-1 may provide a valuable indicator of neonatal condition immediately after birth, the clinical relevance of which needs to be further established.

Adult↗