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Biomedical subjects

J Petrik

Publications and source records attributed to J Petrik.

At least 19 recordsLinked to original sources
PubMed1999

Ontogeny of hepatitis C virus (HCV) hypervariable region 1 (HVR1) heterogeneity and HVR1 antibody responses over a 3 year period in a patient infected with HCV type 2b.

Hypervariable region 1 (HVR1) sequences of 96 clones at six time-points representing 27 variants in two major and one minor group were identified in a patient with chronic hepatitis C virus (HCV) infection over 3 years. Major and selected minor variants were used to design synthetic peptides corresponding to the HVR1 C terminus. Peptide ELISA reactivity with IgG was plotted against the corresponding clone frequency, and three patterns emerged: (1) three peptides were unreactive; (2) antibodies against two peptides followed emergence of the corresponding variant, suggesting isolate-specificity; (3) antibodies against four peptides preceded the appearance of the corresponding variant, indicating cross-reactivity or previous exposure. Cross-reactivity was investigated further: sera from six time-points were tested against 11 unrelated HVR1 peptides, seven of which (63.6%) showed cross-reactivity at all time-points. Cross-reactivity of nine patient-specific peptides tested against a panel of 45 heterologous sera from chronic HCV carriers ranged between 0 and 20%. Only three of 27 variants appeared at more than one time-point and in two cases specific and/or cross-reactive HVR1 antibodies coexisted with the corresponding variant, consistent with emergence of escape mutants. In addition, analysis of HVR1 IgG reactivity within a group of closely related patient-specific peptides revealed a loss of reactivity in one peptide attributable to a single amino acid substitution. Interferon-alpha treatment considerably reduced viral RNA but, paradoxically, heterogeneity increased.

Adult↗
PubMed1999

Overexpression of insulin-like growth factor-II in transgenic mice is associated with pancreatic islet cell hyperplasia.

We have used an insulin-like growth factor (IGF)-II transgenic mouse model in which mouse IGF-II is widely overexpressed, resulting in increased fetal size and selective organ overgrowth, to investigate the effects on the development of the endocrine pancreas. Fetuses examined on day 19.5-20 of gestation had significantly elevated circulating levels of IGF-II, compared with control mice. The pancreatic islets in transgenic animals were of irregular shape and had a mean area five times greater than in controls, whereas the mean number of islets per tissue section was not altered. The size of individual endocrine cells was not altered. Although the islets in animals expressing the IGF-II transgene were considerably larger, immunohistochemistry for insulin and glucagon showed that the relative proportion of beta-cells was significantly less, and that of alpha-cells was higher. Normal islet morphology was disrupted, with alpha-cells appearing in small groups within the islets, as well as on the periphery, whereas beta-cells were often seen at the edge of the islets. Twice as many islet cells (21.9% vs. 11.4%) were involved in cell replication, detected by the presence of immunoreactive proliferating cell nuclear antigen, in pancreata from transgenic mice vs. controls, whereas the number of cells undergoing apoptosis was significantly reduced. Abundant IGF-II messenger RNAwas found within the islets of transgenic animals by in situ hybridization, and the relative area of islets demonstrating immunoreactive IGF-II was significantly greater. Immunoreactive IGF-I was much less abundant and was further reduced in islets of transgenic animals. The area of islets immunopositive for IGF binding protein-2 was unaltered. Despite the presence of islet hyperplasia, circulating insulin levels and serum glucose levels were not significantly different between transgenic and control mice. These results show that an overexpression of IGF-II in fetal life has a profound effect on islet morphology and causes islet hyperplasia while reducing the attrition of islet cells by apoptosis.

Animals↗
PubMed1999

Cellular distribution and ontogeny of insulin-like growth factors (IGFs) and IGF binding protein messenger RNAs and peptides in developing rat pancreas.

To determine the role of insulin-like growth factors (IGFs) and their binding proteins (IGFBPs) in the development of the pancreas, and specifically of the islets of Langerhans, we have examined the cellular distribution and developmental changes in the expression of IGFs and IGFBPs in the pancreas of the fetal and neonatal rat between 19.5 days of gestation and postnatal day 28. This represents a period of substantial growth and restructuring of the beta cell component in islets of this species. IGF-I, IGF-II, and IGFBPs-1 to -6 mRNAs were localized by in situ hybridization, and peptides by immunohistochemistry, in histological sections. IGF-II mRNA was highly expressed in islet cells and some ductal epithelial cells in late fetal and early neonatal life, but was barely detectable by postnatal day 28. IGF-II peptide showed a similar distribution. IGF-I mRNA was barely detected in the fetus or neonate and was localized predominantly in the ductal and acinar tissues after postnatal day 7. IGF-I immunoreactivity was associated with some islet cells in the fetus and neonate, suggesting an endocrine rather than a paracrine source. We performed co-localization studies to assess whether the distribution of IGFs within the pancreas might be due to a sequestration by locally produced IGFBPs. The presence of mRNAs for both IGFBPs-1 and -2 was minimal in the pancreas prior to postnatal day 7, although subsequently IGFBP-1 mRNA was seen in islet cells, while IGFBP-2 mRNA was localized in both islets and acinar tissues. In contrast, both IGFBPs-1 and -2 immunoreactivities were identified in islets from late fetal life, suggesting a circulatory source for these IGFBPs during early pancreatic development. IGFBPs-3 to -5 mRNAs and immunoreactivities were identified within islet cells throughout fetal and neonatal life, with IGFBPs-3 and -5 being mainly associated with the alpha cell-rich islet mantle. The results show a compartmentalization of IGFs within pancreatic tissue, reflecting both paracrine and endocrine sources. The localization and action of IGFs in pancreas likely involves sequestration and distribution by endogenous as well as circulating IGFBPs.

Animals↗
PubMed1999

Insulin-like growth factors prevent cytokine-mediated cell death in isolated islets of Langerhans from pre-diabetic non-obese diabetic mice.

Interleukin-1beta (IL-1beta), tumour necrosis factor-alpha (TNF-alpha) and interferon-gamma (IFN-gamma) contribute to the initial stages of the autoimmune destruction of pancreatic beta cells. IL-1beta is released by activated macrophages resident within islets, and its cytotoxic actions include a stimulation of nitric oxide (NO) production and the initiation of apoptosis. Insulin-like growth factors (IGFs)-I and -II prevent apoptosis in non-islet tissues. This study investigated whether IGFs are cytoprotective for isolated islets of Langerhans from non-obese diabetic mice (NOD) mice exposed to cytokines. Pancreatic islets isolated from 5-6-week-old, pre-diabetic female NOD mice were cultured for 48 h before exposure to IL-1beta (1 ng/ml), TNF-alpha (5 ng/ml), IFN-gamma (5 ng/ml) or IGF-I or -II (100 ng/ml) for a further 48 h. The incidence of islet cell apoptosis was increased in the presence of each cytokine, but this was significantly reversed in the presence of IGF-I or -II (IL-1beta control 3.5+/-1.6%, IL-1beta 1 ng/ml 27.1+/-5.8%, IL-1beta+IGF-I 100 ng/ml 4.4+/-2.3%, P<0.05). The majority of apoptotic cells demonstrated immunoreactive glucose transporter 2 (GLUT-2), suggesting that they were beta cells. Islet cell viability was also assessed by trypan blue exclusion. Results suggested that apoptosis was the predominant cause of cell death following exposure to each of the cytokines. Co-incubation with either IGF-I or -II was protective against the cytotoxic effects of IL-1beta and TNF-alpha, but less so against the effect of IFN-gamma. Exposure to cytokines also reduced insulin release, and this was not reversed by incubation with IGFs. Immunohistochemistry showed that IGF-I was present in vivo in islets from pre-diabetic NOD mice which did not demonstrate insulitis, but not in islets with extensive immune infiltration. Similar results were seen for IGF-binding proteins (IGFBPs). These results suggest that IGFs protect pre-diabetic NOD mouse islets from the cytotoxic actions of IL-1beta, TNF-alpha and IFN-gamma by mechanisms which include a reduction in apoptosis.

Animals↗
PubMed1998

Serum hyaluronic acid is a useful marker of liver fibrosis in chronic hepatitis C virus infection.

Patients with chronic hepatitis C virus (HCV) infection are often asymptomatic with few clinical signs of liver disease. Recognition of the presence of fibrosis or cirrhosis is difficult without liver biopsy, but with the availability of effective treatments, such as interferon, and the potential for progression to hepatoma in some cases, an accurate measure of the stage of disease is important. Serum hyaluronic acid (HA) has been identified as a potential marker of fibrosis or cirrhosis in other settings. In a prospective study in 130 chronic HCV carriers therefore, serum HA concentrations were compared with conventional liver function tests (including alanine aminotransferase (ALT), a-glutathione-S transferase (GST) and serum HCV RNA in order to determine which identified the stage of liver fibrosis as assessed by liver biopsy most accurately. The median HA concentrations according to the stage of fibrosis 0, 1 & 2, 3 and 4 & 5 were 17 g l-1 (range 5-37), 17 g l-1 (5-80), 30 g l-1 (10-105) and 350 g l-1 (20-800) respectively. The median HA concentration in stage 4 & 5 was significantly greater than in stages 0, 1 & 2 or 3. Serum HA concentration rose with age, but even when adjusted for age the median HA at stage 4 & 5 was greater than all other groups (95% CI of difference between the medians exceeded 0). Thus, serum HA gave a sensitivity and specificity for stage 4 & 5 fibrosis of 85% and 88% respectively, exceeding those for ALT or GST. In contrast, serum ALT or GST levels were not correlated with the stage of fibrosis although ALT was significantly greater in the cirrhotic group when compared to the group with no fibrosis (stage 0). There was no correlation between serum HA and either the grade of inflammatory changes or serum HCV RNA. These results suggest that serum hyaluronic acid is a useful marker of liver fibrosis in patients with chronic HCV infection. It could therefore be used to monitor patients at risk of progressive fibrosis, in controlled clinical trials, as a measure of response to antifibrotic therapy and in those in whom liver biopsy is difficult or contraindicated.

Adolescent↗
PubMed1998

Hepatic histology in hepatitis C virus carriers coinfected with hepatitis G virus.

BACKGROUND: A novel flavivirus has been described recently and designated hepatitis G virus (HGV). The virus is transmitted by the parenteral route but it is uncertain whether it is associated with chronic liver disease because liver biopsy is difficult to justify in this group. AIMS: To examine histological features of liver biopsy in patients infected with hepatitis C virus (HCV) according to the presence or absence of HCV and HGV RNA. METHODS: One hundred and thirty one consecutive HCV carriers undergoing staging liver biopsy were studied retrospectively. In each, HCV RNA and HGV RNA were detected by reverse transcription polymerase chain reaction on serum samples collected at the time of biopsy. The presence of each RNA was correlated with histological features blind to the RNA results; individual histological features of inflammation or fibrosis were scored separately. RESULTS: Nineteen patients were positive for both HGV and HCV RNA in serum, 91 were positive for HCV RNA alone, two were positive for HGV RNA alone, and 19 were negative for both RNA species. Neither age nor sex differed between the groups; a greater proportion of intravenous drug users were HGV RNA positive, but this was not statistically significant. There was no effect of HGV coinfection on the stage of fibrosis or any other histological parameter except steatosis; patients with HCV and HGV RNA had a higher mean score for fat than those patients with HCV RNA alone (p < 0.05). CONCLUSIONS: HGV coinfection has no important effects on histological features in chronic HCV carriers. It is unlikely that HGV infection causes chronic liver disease.

Adult↗
PubMed1998

Apoptosis in the pancreatic islet cells of the neonatal rat is associated with a reduced expression of insulin-like growth factor II that may act as a survival factor.

Islet cell ontogeny will define adult beta-cell mass and will consist of a balance of islet cell birth and death. We have investigated the ontogeny of factors that may be related to developmental apoptosis in the islets, insulin-like growth factor II (IGF-II) and inducible nitric oxide synthase (iNOS), in pancreata of young Wistar rats. Pancreata were collected from rats of 21 days gestation to 29 days postnatal age. In situ hybridization and immunohistochemistry showed that IGF-II was expressed and present in fetal and neonatal islet cells, but declined rapidly 2 weeks after birth. Little IGF-I was associated with fetal or postnatal islets. Apoptosis in islet cells was visualized by molecular histochemistry for DNA breakage in tissue sections. Apoptosis was low in the fetus, but increased in incidence postnatally so that 13% of islet cells were undergoing apoptosis on postnatal day 14, with the incidence declining thereafter. Immunohistochemistry for iNOS showed that it was expressed within beta-cells and was most abundant 12 days after birth. When islets were isolated from rat pancreata 20-22 days after birth, islet cell viability, DNA synthetic rate, and insulin release were reduced after incubation with interleukin-1beta, tumor necrosis factor, or interferon-gamma. An increased rate of islet cell survival was found after simultaneous incubation with IGF-I or -II. Cytokine-mediated islet cell death involved the induction of apoptosis. Islets isolated from neonatal rats were not killed after exposure to these cytokines at the same concentrations, but cytokine-induced cell death was seen when neonatal islets were incubated with a neutralizing antibody against IGF-II. These experiments show that a peak of islet cell apoptosis that is maximal in the rat pancreas 14 days after birth is temporally associated with a fall in the islet cell expression of IGF-II. IGF-II was shown to function as an islet survival factor in vitro. The induction of islet cell apoptosis in vivo may involve an increased expression of iNOS within beta-cells.

Animals↗
PubMed1998

Growth factors and the regulation of fetal growth.

Fetal growth demands a coordinated increase in size of the fetus and the placenta, and both are determined, in part, by locally produced peptide growth factors. The availability of growth factors to individual tissues may be due to local changes in gene expression, but it is also controlled by proteolytic release from extracellular matrix stores. Members of the fibroblast growth factor (FGF) family are stored within basement membranes, while insulin-like growth factors (IGFs) are stored in association with specific binding proteins (IGFBPs). Insulin is a major trophic hormone in utero, and pancreatic beta-cell mass is determined by locally produced IGF-II and members of the FGF family. The mitogenic effects of IGF-II on beta-cells are determined by IGFBPs, which are themselves expressed with a distinct ontogeny within the islets of Langerhans. Overexpression of IGF-II or IGFBP-I can result in nesidioblastosis. Shortly after birth in rodents, many pancreatic beta-cells are destroyed by a process of apoptosis but are simultaneously replaced as a result of beta-cell neogenesis. This process may enrich the pancreas in beta-cells suited to the metabolic demands of postnatal life. The wave of beta-cell apoptosis coincides with a dramatic decrease in the local expression of IGF-II. These events may be functionally linked, because exogenous IGF-II will protect isolated islets from cytokine-induced apoptosis. FGF-2 is also widely expressed within fetal tissues and may be an important regulator of placental angiogenesis. FGF-2 appears in the maternal circulation during pregnancy, with peak values late in the 2nd trimester. It is associated with a circulating binding protein derived from the extracellular domain of the FGFR1 receptor. Levels of FGF-2 in maternal serum correlate positively with fetal size both in the 2nd trimester and at term. The expression of FGF-2 in placenta and its presence in maternal blood are elevated in pregnancies complicated by diabetes and are greatest in diabetic pregnancies associated with retinopathy. Thus, maternal FGF-2 may be a useful indicator of both fetal development and the risk of maternal pathology in pregnancies complicated by diabetes.

Animals↗
PubMed1997

Hepatitis C virus genomic variability in untreated and immunosuppressed patients.

To investigate whether immune pressure enhances the genetic diversity of the hepatitis C virus (HCV) hypervariable region 1, nucleotide sequences were compared in multiple sera, collected longitudinally, from three untreated patients and four patients undergoing liver transplantation for HCV-related cirrhosis. A minor variant became dominant in three of three patients following transplantation and persisted unchanged for months. Compared with untreated HCV carriers, transplant recipients had fewer quasispecies, fewer nucleotide changes (1.61 and 2.58/month), fewer amino acid sequence changes (0.40 and 1.94/month), as well as higher ratio of transitional to transversional mutations (2.57 and 0.98, P < 0.02) and lower replacement to silent mutations (1.33 and 8.21, P < 0.01). The two patients with the least genomic variation died of HCV graft infection. The data suggest that HCV variants which infect the graft are selected by recipient immune pressure at the time of transplant and that preferential replication in the graft is enhanced by routine immunosuppression.

Amino Acid Sequence↗
PubMed1997

Reactivity of synthetic peptides representing selected sections of hepatitis C virus core and envelope proteins with a panel of hepatitis C virus-seropositive human plasma.

A series of 54 synthetic peptides, 15-20 residues long, that represented selected parts of the structural proteins of hepatitis C virus (HCV) were tested for immunoreactivity with a panel of 45 plasma samples from potential blood donors who were known to be seropositive for anti-HCV. Most of the ten peptides that represented the core protein showed reactivity with most of the panel samples. All except one of the 20 peptides that represented non-hypervariable regions of envelope proteins E1 and E2 showed little or no reactivity. In contrast, 18 of the the 24 peptides that represented variants of the hypervariable region 1 of the E2 protein reacted with at least one panel sample. Notably, 40% of the panel samples cross-reacted with two or more different peptides sequences some of which differed by more than 50%. Two panel samples each cross-reacted with seven different peptide sequences. The results suggest a broad anti-hypervariable region antibody specificity in many anti-HCV-seropositive samples and possible limits on the mutability of hypervariable region sequences. The work contributes to understanding the immunogenicity and persistence of HCV.

Amino Acid Sequence↗
PubMed1997

High throughput PCR detection of HCV based on semiautomated multisample RNA capture.

An amplification procedure based on a semiautomated 60-sample RNA capture, including combined reverse transcription/polymerase chain reaction (RT-PCR) and nested PCR/Taqman amplicon detection. is described. It can be completed within a working day and is suitable for the development of a fully automated system. HCV RNA-specific capture is independent of the sequence variations as it targets the poly(U) tract commonly present at the 3'-end of the HCV genome (U-capture). The type specificity of the assay determined in a panel of 56 confirmed HCV antibody-positive samples (genotypes 1-6) was slightly better when compared to a commercial assay. The sensitivity evaluated on serial dilutions of representative samples was equal for genotypes 1, 2, 5, 6, or increased for genotypes 3 and 4 with the U-capture assay.

Automation↗
PubMed1997

The role for liver biopsy in haemophiliacs infected with the hepatitis C virus.

Assessment of chronic hepatitis C virus infection requires a liver biopsy in most circumstances. There is a reluctance to perform liver biopsy in haemophiliacs because of a perceived risk of haemorrhage, although with adequate factor concentrate replacement in patients without factor concentrate inhibitors it should be safe. We report a 4-year experience of liver biopsy in patients with haemophilia infected with chronic hepatitis C virus. Of 55 patients seropositive for anti-HCV, 35 have undergone liver biopsy; the median age of this group was 33 years (range 13-68). Seven patients had a normal liver. 22 had portal tract inflammation, four with lymphoid aggregates. Mild piece-meal necrosis was observed in only two and no bile duct injury was found. 11 patients had mild mixed micro- and macro-vesicular fat. 19 patients had no evidence of fibrosis despite an estimated median duration of disease of 20 years (range 8-43). In the remaining 16 patients the maximum degree of fibrosis achieved was stage III. Patients with more significant fibrosis could not be identified on the basis of ALT or HCV RNA. There were no complications of liver biopsy in this series. Liver biopsy following a well-defined protocol in chronic hepatitis C virus haemophiliac carriers is safe in the absence of factor concentrate inhibitors. In this young group of patients without HIV infection there was no evidence of significant liver disease despite a considerable duration of disease. Performing liver biopsy allows accurate information to be given to the patient and avoids unnecessary therapy. The relative youth of this group may be important in the light of the benign histology.

Adolescent↗
PubMed1997

Importance of age in chronic hepatitis C virus infection.

This study was designed to investigate the value of liver biopsy in the management of patients with chronic hepatitis C virus infection and to identify risk factors for fibrosis. It was a prospective audit of clinical, biochemical, virological and radiological features for predicting liver fibrosis in 140 consecutive patients seropositive for antibody against hepatitis C virus. Seventy-five per cent of patients were asymptomatic and 69% had no clinical signs of chronic liver disease. Serum transaminase levels were normal in 44% of patients, less than twice normal in 35% and more than twice normal in 21%. Ultrasound scan was unremarkable in 85%. Sixty-nine per cent of patients were viraemic at the time of liver biopsy. Liver histology revealed that fibrosis was absent in only 10% of patients (stage 0) while cirrhosis was evident in 7% (stage 5). Liver fibrosis was detected in 90% of patients (stage 1, 11%; stage 2, 41%; stage 3, 21%; and stage 4, 10%). Univariate analysis showed that increasing age, clinical signs of chronic liver disease and abnormal ultrasound scan findings were associated with liver fibrosis (P<0.05); however, multiple linear regression analysis of all the clinical features did not reveal a useful model (sensitivity 42% and specificity 23%) for predicting liver fibrosis. Hence, no combination of clinical, biochemical, virological or radiological data was reliable in discriminating the stage of liver fibrosis in patients with chronic hepatitis C virus infection. However, older patients, especially those with clinical signs of chronic liver disease and abnormal ultrasound scan findings, were more likely to have advanced fibrosis. We recommend liver biopsy as the single most important investigation in detecting liver fibrosis.

Adolescent↗
PubMed1996

Ankle arthroscopy: outcome in 79 consecutive patients.

Seventy-nine consecutive ankle arthroscopies were analyzed at a minimum 2-year follow-up to evaluate the risks and benefits of the procedure. All arthroscopies were performed over a 2-year period by a single surgeon using the same nonskeletal traction technique. Forty-four arthroscopies were performed for therapeutic reasons only, whereas 35 were performed for both diagnostic and therapeutic purposes. Clinical examination with visual analog scores were used for assessment preoperatively and postoperatively. The diagnoses were osteochondral lesions of the talus in 21; post-ankle fracture scarring in 14, osteoarthritis and chondromalacia in 11, anterior bony impingement in 14; anterolateral soft tissue impingement or synovitis in 15; miscellaneous diagnosis in 4. Overall, 63 of 79 patients benefited in some way from the procedure. There were diagnostic benefits in 27 of 35 (77%) of ankles in which the diagnosis was clarified by the arthroscopy. In those ankles in which the procedure was performed for therapeutic purposes only, 36 of 44 (82%) of the patients benefited. Those patients with an underlying diagnosis of osteoarthritis of the ankle, posttraumatic chondromalacia and arthrofibrosis, or who were on disability and worker's compensation benefits, had poor results, whereas patients with a localized osteochondral lesion of the talus, localized bony or soft tissue impingement, or localized lateral plica had the best results. There were three significant neurological complications from ankle arthroscopy in this series. Two patients developed a postoperative partial deep peroneal nerve neuropraxia, and one patient had superficial peroneal nerve irritation at the site of the anterolateral portal. Ankle arthroscopy appears to be a relatively low-risk procedure with substantial benefits, particularly in localized disease of the ankle joint. Skeletal distraction was not used in any of these cases.

Adolescent↗
PubMed1996

Safety and efficacy of hepatitis C virus antibody screening of blood donors with two sequential screening assays.

BACKGROUND: Reactive samples in hepatitis C virus (HCV) antibody screening of blood donors are currently referred for a confirmatory assay. This scheme is not optimally efficient and is expensive because of the lack of specificity and cost of confirmatory tests, as well as the need to discard false-positive donations. As in some human immunodeficiency virus antibody-confirmatory schemes, the safety and efficacy of confirming anti-HCV with two sequential screening assays were evaluated. STUDY DESIGN AND METHODS: Three combinations of two anti-HCV screening assays were used to test 75,874 blood donors. Results were compared with the routine testing scheme and HCV RNA detection in any enzyme immunoassay-repeatably reactive samples. RESULTS: The use of an alternative screening assay for repeat testing decreased the proportion of enzyme immunoassay-positive donors from 0.28 to 0.05 percent. All samples that were "confirmed" as positive by the standard combination of immunoassays and all HCV RNA-positive samples were detected by the sequential screening assays. No samples that had discordant results on primary and secondary screening assays were confirmed by recombinant immunoblot assay or were found to contain detectable HCV RNA. CONCLUSION: The combination of screening assays for anti-HCV confirmation was as safe as, cheaper than, and nearly as efficient as the standard testing scheme.

Blood Donors↗
PubMed1995

Ochratoxin A impairs activity of the membrane bound enzymes in rat pancreas.

Ochratoxin A is a mycotoxin produced by Aspergillus ochraceus and is a natural contaminant of moldly food. Ochratoxin A has a number of toxic effects, some of which may be related to the changes in the cell membrane. We measured the activities of 5 pancreatic, membrane bound enzymes in female Fisher rats that were given low oral doses of ochratoxin A (120 micrograms/kg body weight per day) during 20-35 days. The amount of toxin corresponds to 1.5 mg/kg in the feed, daily. These doses are in the range of natural contamination found in feed. The enzymes studied were alanine aminopeptidase, alkaline phosphatase, ecto-Ca2+/Mg(2+)-ATPase, gamma-glutamyl transferase and ecto-5'-nucleotidase. Treatment lasting 20 days caused a strong decrease in the activity of alanine aminopeptidase, Ca2+/Mg(2+)-ATPase and alkaline phosphatase to 0.76 +/- 0.04, 0.53 +/- 0.03 and 0.30 +/- 0.02 of the control values, respectively (p < 0.05). No significant changes in the activity of gamma-glutamyl transferase and 5'-nucleotidase were observed. However, activity of alanine aminopeptidase returned to normal values after 35 days of treatment, suggesting an adaptation of the organism, or a substitution of a released enzyme. Activities of alkaline phosphatase and Ca2+/Mg(2+)-ATPase remained significantly reduced to 0.42 +/- 0.03 and 0.52 +/- 0.04, respectively (p < 0.01). We conclude that treatment of rats with low doses of ochratoxin A resulted in reduction of the activities of the membrane bound enzymes, most probably by inducing their release, as a result of the impairment of the functional integrity of cell membranes.

5'-Nucleotidase↗
PubMed1994

TOCOEN project.

The basic goals of the TOCOEN project (Toxic Organic COmpounds in the ENvironment) are to detect and understand the fate of selected organic pollutants (PAHs, PCBs and PCDDs/Fs mainly) in the environment. The TOCOEN project was established in 1988 as a free association of Czech and Slovak environmental chemists, ecototoxicologists and other environmentalists.

Air Pollutants↗