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Biomedical subjects

A A Fryer

Publications and source records attributed to A A Fryer.

108 records · Page 6Linked to original sources
PubMed1994

Progression of cervical intraepithelial neoplasia to cervical cancer: interactions of cytochrome P450 CYP2D6 EM and glutathione s-transferase GSTM1 null genotypes and cigarette smoking.

The factors that determine progression of cervical intraepithelial neoplasia (CIN) to squamous cell carcinoma (SCC) are unknown. Cigarette smoking is an independent risk factor for cervical neoplasia, suggesting that polymorphism at detoxicating enzyme loci such as cytochrome P450 CYP2D6 and glutathione S-transferase GSTM1 may determine susceptibility to these cancers. We have studied the frequencies of genotypes at these loci in women suffering low-grade CIN, high-grade CIN and SCC. A non-cancer control group was provided by women with normal cervical histology suffering menorrhagia. Comparison of the frequency distributions of the CYP2D6 PM, HET and EM genotypes (G-->A transition at intron 3/exon 4 and base pair deletion in exon 5) revealed no significant differences between the menorrhagia and SCC groups. Frequency distributions in the menorrhagia group, however, were significantly different (P < 0.04) from those in the low- and high-grade CIN groups. Thus, the proportion of EM was significantly larger (P < 0.03) and of HET generally lower. We found that the frequency of GSTM1 null in the menorrhagia and case groups was not significantly different. Interactive effects of enzyme genotypes with cigarette smoking were studied by comparing the multinomial frequency distributions of CYP2D6 EM/GSTM1 null/smoking over mutually exclusive categories. These showed no significant differences between the menorrhagia group and SCC or low-grade CIN groups. The frequency distribution in high-grade CIN, however, was significantly different to that in the menorrhagia group and in both SCC and low-grade CIN groups. This study was identified, for the first time, an inherited characteristic in women with high-grade CIN who appear to be at reduced risk of SCC. Thus, women with CYP2D6 EM who smoke have increased susceptibility to high-grade CIN but are less likely to progress to SCC, possibly because they effectively detoxify an unidentified chemical involved in mediating disease progression.

Adult↗
PubMed1993

Use of site-directed mutagenesis of allele-specific PCR primers to identify the GSTM1 A, GSTM1 B, GSTM1 A,B and GSTM1 null polymorphisms at the glutathione S-transferase, GSTM1 locus.

We describe the identification of the GSTM1 null, GSTM1 A, GSTM1 B and GSTM1 A,B polymorphisms at the glutathione S-transferase GSTM1 locus using a single-step PCR method. Target DNA was amplified using primers to intron 6 and exon 7 with site-directed mutagenesis being used to introduce a restriction site in DNA amplified from GSTM1 *A, thereby allowing differentiation of this allele and GSTM1 *B. The accuracy of this approach in identifying the GSTM1 A, GSTM1 B, GSTM1 A,B and GSTM1 null polymorphisms was confirmed by comparison with, firstly, an established PCR method that distinguishes GSTM1 *0 homozygotes from individuals with the other GSTM1 genotypes and, secondly, GSTM1 phenotypes determined using chromatofocusing.

Alleles↗
PubMed1993

The glutathione S-transferases: polymerase chain reaction studies on the frequency of the GSTM1 0 genotype in patients with pituitary adenomas.

The frequency of the GSTM1 0 polymorphism at the glutathione S-transferase M1 locus has been determined in controls and patients with pituitary adenomas by using the polymerase chain reaction to amplify genomic DNA in the exon 4-5 region of the gene. The frequency of the genotype in patients with prolactinomas, non-functional adenomas, corticotrophinomas and somatotrophinomas varied between 52-67% compared with 44% in the controls. In the patients with prolactinomas the frequency of the genotype (67%) was significantly greater than in controls with odds ratio analysis indicating that GSTM1 0 individuals have a 2.56-fold greater risk of developing this adenoma.

Adenoma↗
PubMed1993

Plasma protein levels in normal human fetuses: 13 to 41 weeks' gestation.

OBJECTIVES: To establish reference ranges for the levels of alpha-fetoprotein, albumin, prealbumin (transthyretin) alpha-1-antitrypsin, transferrin, ceruloplasmin and total protein in the plasma of normal human fetuses and newborn babies. DESIGN: Prospective study of individual normal cases to fulfil objectives. SETTING: Pathology laboratories of the University of Edinburgh and the biochemistry laboratories of the University of Keele. SUBJECTS: Twenty-two normal fetuses 13 to 22 weeks of gestation and 66 babies born between 24 and 41 weeks gestation. RESULTS: Albumin is the predominant plasma protein throughout gestation. The levels of alpha-fetoprotein and prealbumin fell significantly with increasing gestation, whereas the concentrations of the other proteins studied increased. The ratios of individual proteins to total protein demonstrated similar trends. CONCLUSIONS: This study provides developmental profiles of normal human fetal plasma proteins to serve as possible reference data for abnormal fetuses. Declining levels of prealbumin (transthyretin) were unexpected and suggest a functional role for this protein in early pregnancy.

Blood Proteins↗
PubMed1993

GSTM1 null polymorphism at the glutathione S-transferase M1 locus: phenotype and genotype studies in patients with primary biliary cirrhosis.

Studies were carried out to test the hypothesis that the GSTM1 null phenotype at the mu (mu) class glutathione S-transferase 1 locus is associated with an increased predisposition to primary biliary cirrhosis. Starch gel electrophoresis was used to compare the prevalence of GSTM1 null phenotype 0 in patients with end stage primary biliary cirrhosis and a group of controls without evidence of liver disease. The prevalence of GSTM1 null phenotype in the primary biliary cirrhosis and control groups was similar; 39% and 45% respectively. In the primary biliary cirrhosis group all subjects were of the common GSTM1 0, GSTM1 A, GSTM1 B or GSTM1 A, B phenotypes while in the controls, one subject showed an isoform with an anodal mobility compatible with it being a product of the putative GSTM1*3 allele. As the GSTM1 phenotype might be changed by the disease process, the polymerase chain reaction was used to amplify the exon 4-exon 5 region of GSTM1 and show that in 13 control subjects and 11 patients with primary biliary cirrhosis, GSTM1 positive and negative genotypes were associated with corresponding GSTM1 expressing and non-expressing phenotypes respectively. The control subject with GSTM1 3 phenotype showed a positive genotype.

Base Sequence↗
PubMed1993

Alpha, mu and pi class glutathione S-transferases in human synovium and cultured synovial fibroblasts: effects of interleukin-1 alpha, hydrogen peroxide and inhibition of eicosanoid synthesis.

We describe expression of alpha, mu and pi class glutathione S-transferase (GST) and, CuZn- and Mn superoxide dismutase (SOD) in human synovium and cultured synovial fibroblasts. Immunohistochemical and immunoblotting studies showed synovium and cultured cells expressed pi GST and both isoforms of SOD. Cellular localisation was largely perinuclear. No expression of alpha or mu GST was detected even though polymerase chain reaction analysis showed 4/6 subjects had positive genotypes at the polymorphic, mu class GSTM1 locus. Incubation of cultured synovial fibroblasts with H2O2, IL-1 alpha and the cyclooxygenase and lipoxygenase inhibitor, Tenidap, did not induce expression of alpha, mu or pi GST though treatment with IL-1 alpha caused a marked increase in the expression of Mn SOD.

Arthritis, Rheumatoid↗
PubMed1992

The human glutathione S-transferases: comparison of isoenzyme expression in normal and astrocytoma brain.

We describe expression of alpha, mu and pi class glutathione S-transferases (GST) in brain tissue from 21 controls and uninfiltrated and tumour tissue from 17 glioma patients. GST were sequentially resolved by chromatofocusing into the GST2, GST1, GST5, GST2 (5.5), GST3, GST6 sets and the contribution of each to total activity determined. The immunological identity of these isoforms was studied using immunoblotting. The pi class GST3 isoform was the major contributor to activity in control tissue (70.9%) and, uninfiltrated (75.1%) and tumour samples (82.4%). Expression was significantly greater in the tumours (P less than 0.05). Expression of alpha isoforms GST2 and GST2 (5.5) was variable with most subjects demonstrating no detectable GST2 (B1 and B2 chromatofocused monomers). An isoform termed GST2 (5.5) chromatofocussed at pH 5.5 and cross-reacted with antisera to B1. It was detected in most control and glioma patients and comprised about 5% of total activity. The contribution of GST2 and GST2 (5.5) to activity was similar in control, uninfiltrated and tumour tissue. Two mu class enzymes, GST1 and GST5, were identified. GST1 isoforms were detected in 9 of 21 control samples, the phenotype of these and matched liver samples were identical. GST1 isoforms were detected in 4 of 16 tumour samples, a significantly lower incidence than in a previously established control group. GST5 was expressed in most samples, the contribution of this locus to activity was significantly reduced in the tumours (5.2%) compared with control samples (14.5%).

Astrocytoma↗
PubMed1991

Developmental profile of plasma proteins in human fetal cerebrospinal fluid and blood.

Total protein, alphafetoprotein, albumin, prealbumin, alpha-1-antitrypsin, transferrin and ceruloplasmin levels were measured in samples of human fetal and neonatal cerebrospinal fluid (CSF) (97 cases), obtained between 12 and 41 weeks of gestation. In 39 of these cases (13 to 40 weeks gestation) plasma was also available for comparative analysis. CSF was collected from lateral ventricles in the first half of gestation and from the lumbar region in the second. Since these CSF samples were obtained from different sites, the protein levels in the lateral ventricle (early) samples could not be compared directly with those in the lumbar (later) samples. However, the mean protein levels in the lumbar samples were lower than those in the ventricular samples, which is in accord with the decline in CSF protein levels described in maturing animal fetuses. Despite a wide scatter of results, particularly in the first half of gestation, significant decline in the level of CSF alphafetoprotein was demonstrated during both first and second halves of gestation, and of albumin and prealbumin in the second half. No sex differences were found except for ceruloplasmin in lumbar CSF later in gestation, when males had higher levels than females. In fetal plasma, protein levels increased with increasing gestation apart from alphafetoprotein and prealbumin which both declined progressively. CSF/plasma ratios were dissimilar for different proteins, and changed with increasing gestation. These findings support the concept that the human fetal blood brain barrier matures early.

Blood Proteins↗
PubMed1990

Glutathione S-transferase in human brain.

The glutathione S-transferases are a complex group of multifunctional enzymes which may detoxify a wide range of toxic substances including drugs and carcinogens. Different isoenzymes vary in substrate specificity, tissue distribution and level of expression during development. Following reports of cell-specific and age-dependent expression in rat brain we have studied, immunohistochemically, expression of the Pi and Alpha class isoenzymes in 10 adult and 21 human fetal brains. Whilst Alpha isoenzyme is expressed only in adult brain, and then only focally, Pi isoenzyme is strongly expressed from as early as 12 weeks gestation. In the adult, expression is localized to choroid plexus, vascular endothelium, ventricular lining cells, pia-arachnoid and astrocytes. In fetal brain, expression is also strong in cells with the morphology of tanycytes and in the cell bodies of radial glia. Neurons are consistently negative. Pi isoenzyme thus localizes to the sites of the blood-CSF barrier, blood-brain barrier, CSF-brain barrier and pia-arachnoid-brain barrier. It is ideally placed to regulate neuronal exposure to potentially toxic substances derived from blood or cerebrospinal fluid. Expression so early in gestation is of significance and may imply a role in protection of the developing human brain.

Adult↗
PubMed1990

Lipid peroxidation and expression of copper-zinc and manganese superoxide dismutase in lungs of premature infants with hyaline membrane disease and bronchopulmonary dysplasia.

The putative involvement of reactive oxygen species in the etiology of lung damage in infants receiving mechanical ventilation has been examined by comparing the levels of peroxidation and expression of the antioxidant enzymes, CuZn and Mn superoxide dismutase, in lungs from control and affected infants as well as from fetuses and infants who died postnatally after term delivery. Mean levels (+/- SD) of lung peroxidation, determined with a thiobarbituric acid method, were similar in affected and control premature neonates and in fetal subjects (1.87 +/- 1.26, 1.92 +/- 2.07, and 1.19 +/- 1.36 nmol/mg protein, respectively). Expression of CuZn and Mn superoxide dismutases was also similar in these subjects and in the patients who died postnatally. Thus activity measurements and immunoblotting studies showed continuous expression of these enzymes throughout development with no apparent change in protein levels or size. Immunohistochemical examination of lung tissue showed expression of CuZn and Mn superoxide dismutases in epithelial, smooth muscle, endothelial, and some mesenchyme components. In patients with bronchopulmonary dysplasia, alveolar walls were thickened by an excess of fibrous tissue and terminal air spaces were lined mainly by type II pneumatocytes. All structures, including abnormal fibrous components, were positive for both CuZn and Mn superoxide dismutase. Our data show that, unlike some experimental animals, expression of at least these antioxidant enzymes in human infants born prematurely is similar to that in adults, and indicate that such infants are better adapted for life in an oxygen-containing environment than previously suspected.(ABSTRACT TRUNCATED AT 250 WORDS)

Bronchopulmonary Dysplasia↗
PubMed1988

Studies on the expression of Cu,Zn superoxide dismutase in human tissues during development.

The developmental expression of Cu,Zn superoxide dismutase in human lung and erythrocytes has been studied using activity measurements, immunoblotting and immunohistochemistry. Enzyme activity in erythrocytes increased significantly during gestation but no developmental trend was seen in lung. Immunoblotting identified a single enzyme form that was present in a variety of tissues and immunohistochemistry showed the enzyme to have widespread distribution in lung tissue. These data indicate that Cu,Zn superoxide dismutase is consistently expressed during human development and that, unlike in other species, no late-fetal surge in expression occurs.

Cytosol↗
PubMed1987

Studies on the developmental expression of glutathione S-transferase isoenzymes in human heart and diaphragm.

The developmental expression of the basic, near-neutral and acidic isoenzymes of glutathione S-transferase (RX:glutathione R-transferase, EC 2.5.1.18) has been studied in heart and diaphragm. Neither these enzymes nor the putative muscle-specific GST4 isoenzyme demonstrated any developmental trends in expression. In vitro hybridisation and SDS-discontinuous polyacrylamide gel electrophoresis were used to show that the GST4 isoenzyme is a homodimer composed of monomers that have a slightly larger molecular weight than the near-neutral isoenzyme. The sensitivity of GST4 to inhibitors also appeared similar to that of the GST1 2 isoenzyme. Immunodiffusion and immunoblotting techniques were used to show that the acidic enzyme in muscle is immunologically identical to that in other tissues.

Chromatography↗
PubMed1986

The development of glutathione S-transferase and glutathione peroxidase activities in human lung.

The development of glutathione S-transferase and glutathione peroxidase activities has been studied in human lung cytosols. Whilst no clear change in glutathione peroxidase activity was identified, expression of the acidic glutathione S-transferase isoenzyme decreased markedly after 15 weeks of gestation so that at birth the level of activity of this isoenzyme was only about 20% of that in samples obtained during the first trimester. Basic glutathione S-transferase isoenzymes were weakly expressed during development and usually comprised less than 10% of cytosolic activity. Ion-exchange studies identified several basic isoenzymes that may correspond to the alpha, beta, gamma, delta and epsilon set previously identified in liver. Weak expression of apparently near-neutral isoenzymes was also detected; they were detected in only a few cytosols.

Chromatography, Ion Exchange↗
PubMedDate not supplied

Glutathione S-transferase GSTM1 and GSTT1 genotypes in ovarian cancer: association with p53 expression and survival.

The objective of this study was to determine whether the association between GSTM1 null/GSTTI null and survival in ovarian cancer is mediated by the influence of these genes on p53 expression. In 81 women with pure invasive ovarian cancer, GSTM1 null and GSTT1 null genotypes were identified using polymerase chain reaction and p53 expression was assessed using immunohistochemistry. The association of these factors with survival was examined using Cox's proportional hazards regression models. Performance status (P < 0.001), operative stage (P = 0.004), residual disease (P = 0.001), histologic subtype (P = 0.05), tumor grade (P = 0.007), and the combined GSTMI null/GSTTl null genotype (P = 0.023) were all individually associated with survival. p53 expression was not associated with survival (P = 0.45). In a multivariate analysis, the effects of GSTM1 null/GSTT1 null on survival were lost when residual disease and tumor grade were included. The effects of p53 expression on survival were unchanged when residual disease, tumor grade, operative stage, and performance score were included. GSTM1 null/GSTT1null did not influence the effects of p53 expression on survival and vice versa. The GSTM1 null/GSTT1 null genotype was associated with response to primary chemotherapy (P = 0.007) but p53 expression was not. We conclude that the association of GSTM1 null/GSTTl null with survival appears to be mediated through different mechanisms to p53 expression in ovarian cancer and in addition, may be a better predictor of outcome.

Adult↗
PubMedDate not supplied

The role of polymorphisms of glutathione S-transferases GSTM1, M3, P1, T1 and A1 in susceptibility to alcoholic liver disease.

AIMS AND METHODS: Oxidant stress is proposed to be an important pathogenic factor in liver damage related to alcohol. The glutathione S-transferases (GSTs) are a group of polymorphic enzymes that are important in protection against oxidant stress. As there is evidence for genetic susceptibility to alcohol-related liver disease we have compared the frequency of polymorphisms of GSTM1, M3, P1, T1 and A1 by polymerase chain reaction (PCR) on leucocyte DNA in patients from North Staffordshire, Birmingham and Liverpool with alcohol-related chronic liver disease heavy drinking and normal local controls. RESULTS: There were no significant differences in GSTM1, GSTM3 or GSTP1 genotype frequencies among patients, drinking and non-drinking controls from the three centres. There was a significant increase in the GSTT1 null Liverpool alcoholic liver disease (ALD) patients compared with corresponding non-drinking controls (26.3 and 14.6%, respectively; P = 0.044, odds ratio (OR) = 2.1, 95% CI = 1.1-4.7) though this was not repeated in the Birmingham and North Staffordshire cohorts. For GSTA1, the -69 CC genotype was associated with increased risk of ALD in the Liverpool group, but a reduced risk in the North Staffordshire group. CONCLUSIONS: We have failed to demonstrate within the limitation of a case-control study a reproducible significant association of GST polymorphisms with susceptibility to ALD but there are suggestions that GSTA1 and GSTT1 warrant further study.

Chi-Square Distribution↗
PubMedDate not supplied

Association between glutathione-S-transferase GSTP1 genotypes, GSTP1 over-expression, and outcome in epithelial ovarian cancer.

Ovarian cancer accounts for the majority of deaths from gynaecological malignancy, and polymorphisms in genes encoding the glutathione-S-transferase (GST) GSTP1 detoxifying enzymes may lead to variation in detoxification of carcinogens. We describe a study involving 81 women with invasive epithelial ovarian cancer. A number of important clinical variables and outcome data were obtained. GSTP1 genotyping was undertaken using PCR-based techniques, and GSTP1 expression was quantified using immunohistochemistry (IHC). A Cox's proportional hazard regression model was used to analyze the effects on outcome. We also independently examined 11 women with borderline or low malignant potential (LMP) tumors using IHC only. The mean age of the women was 61.5 years +/- 12 (1 SD) (range 36-88 years), the median overall survival was 26 months, and median progression free interval (PFI) 21 months. There was a significant association between GSTP1 (Val(104)/Val(104)) genotypes, and reduced survival (P = 0.05) and the GTP1 (Ile(104)/Val(104)) genotype appeared to have the best outcome (HR = 0.34, P = 0.045, 95% CI = 0.12-0.98). There was no significant association between the GSTP1 genotypes and any clinico-pathological parameters; there were also no associations between GSTP1 genotypes and response to postoperative chemotherapy. Specific nuclear GSTP1 over-expression was associated with less residual disease (P = 0.05); specific cytoplasmic GSTP1 over-expression with more favourable performance status (P = 0.014)). We found that 10/11 (91%) of the LMP (borderline) tumors over-expressed nuclear GSTP1 compared to only 52% of the invasive tumors (chi(2) ((1)) = 5.95, P = 0.015). There was no significant association between the level of GSTP1 expression and response to postoperative chemotherapy. The overall level of GSTP1 expression and the subcellular localization of GSTP1 expression were not associated with either survival or PFI. There was a significant association between the GSTP1 (Ile(104)/Ile(104)) genotypes and increased overall GSTP1 expression (P = 0.049), and the GSTP1 (Ile(104)/Val(104)) genotypes and reduced overall GSTP1 expression (P = 0.046). We speculate that GSTP1 Ile(104)/Val(104) genotypes are associated with improved outcome because the protein/enzyme, which is expressed, may provide a better balance between the effects of detoxification of carcinogens and the effects of metabolism of chemotherapy agents. In addition, over-expression of nuclear GSTP1 appears to be associated with more favorable ovarian tumor characteristics. In our preliminary study, we also reported a relationship between overall GSTP1 expression and certain GSTP1 genotypes. As far as we are aware, this is the first time that a relationship between the GSTP1 genotypes, GSTP1 expression and outcome has been described in ovarian cancer. Whether the genotype directly determines GSTP1 expression is at present unclear and the precise mechanism of this interaction is unknown.

Adult↗
PubMedDate not supplied

A comparison of risk factors for malignant melanoma, squamous cell carcinoma and basal cell carcinoma in the UK.

Cutaneous malignant melanoma (MM), squamous cell carcinoma (SCC) and basal cell carcinoma (BCC) exhibit markedly different natural histories, but few studies have compared risk factors in individuals from a single population. Using logistic regression analysis in case and control groups, we assessed, the association of individual characteristics with MM (n = 240) and SCC (n = 184). We also compared differences in risk factors (eye/hair colour, skin type, smoking history, occupation, social class, tumour site) between MM/BCC and SCC/BCC. MM patients were more likely to have red/blonde hair and blue/green eyes than controls, and those with SCC more likely to have red/blonde hair, blue/green eyes, outdoor occupation, skin type 1 and to have smoked more. There were few differences in individual characteristics between the skin cancer groups, illustrating their non-specific nature. Tumour site, however, showed marked differences: MM patients were more likely to have a tumour on the trunk or limbs than BCC patients, while patients with SCC were more likely to have a tumour on the limbs. Reasons for this variation are unclear. The relatively weak effect of individual factors supports the view of a multifactorial disease and suggests that interactions between UV exposure and genetic predisposition may be more significant determinants of risk.

Adult↗