QSAR models for anti-androgenic effect--a preliminary study.

Three modelling systems (MultiCase®, LeadScope® and MDL® QSAR) were used for construction of androgenic receptor antagonist models. There were 923-942 chemicals in the training sets. The models were cross-validated (leave-groups-out) with concordances of 77-81%, specificity of 78-91% and sensitivity of 51-76%. The specificity was highest in the MultiCase® model and the sensitivity was highest in the MDL® QSAR model. A complementary use of the models may be a valuable tool when optimizing the prediction of chemicals for androgenic receptor antagonism. When evaluating the fitness of the model for a particular application, balance of training sets, domain definition, and cut-offs for prediction interpretation should also be taken into account. Different descriptors in the modelling systems are illustrated with hydroxyflutamide and dexamethasone as examples (a non-steroid and a steroid anti-androgen, respectively). More research concerning the mechanism of anti-androgens would increase the possibility for further optimization of the QSAR models. Further expansion of the basis for the models is in progress, including the addition of more drugs.

QSAR models for P450 (2D6) substrate activity.

Human Cytochrome P450 (CYP) is a large group of enzymes that possess an essential function in metabolising different exogenous and endogenous compounds. Humans have more than 50 different genes encoding CYP enzymes, among these a gene encoding for the CYP isoenzyme 2D6, a CYP able to metabolise drugs and other chemicals. A training set of 747 chemicals primarily based on in vivo human data for the CYP isoenzyme 2D6 was collected from the literature. QSAR models focusing on substrate/non-substrate activity were constructed by the use of MultiCASE, Leadscope and MDL quantitative structure-activity relationship (QSAR) modelling systems. They cross validated (leave-groups-out) with concordances of 71%, 81% and 82%, respectively. Discrete organic European Inventory of Existing Commercial Chemical Substances (EINECS) chemicals were screened to predict an approximate percentage of CYP 2D6 substrates. These chemicals are potentially present in the environment. The biological importance of the CYP 2D6 and the use of the software mentioned above were discussed.

QSAR models for reproductive toxicity and endocrine disruption in regulatory use--a preliminary investigation.

A special challenge in the new European Union chemicals legislation, Registration, Evaluation and Authorisation of Chemicals, will be the toxicological evaluation of chemicals for reproductive toxicity. Use of valid quantitative structure-activity relationships (QSARs) is a possibility under the new legislation. This article focuses on a screening exercise by use of our own and commercial QSAR models for identification of possible reproductive toxicants. Three QSAR models were used for reproductive toxicity for the endpoints teratogenic risk to humans (based on animal tests, clinical data and epidemiological human studies), dominant lethal effect in rodents (in vivo) and Drosophila melanogaster sex-linked recessive lethal effect. A structure set of 57,014 European Inventory of Existing Chemical Substances (EINECS) chemicals was screened. A total of 5240 EINECS chemicals, corresponding to 9.2%, were predicted as reproductive toxicants by one or more of the models. The chemicals predicted positive for reproductive toxicity will be submitted to the Danish Environmental Protection Agency as scientific input for a future updated advisory classification list with advisory classifications for concern for humans owing to possible developmental toxic effects: Xn (Harmful) and R63 (Possible risk of harm to the unborn child). The chemicals were also screened in three models for endocrine disruption.

Occupational arsenic exposure and glycosylated haemoglobin.

In a group of 40 workers occupationally exposed to arsenic (As workers) biological markers for cardiovascular diseases were studied. The median arsenic concentration in urine samples from the exposed group was 22.3 nmol of As per mmol of creatinine, while the individual maximum level was 294.5 nmol of As per mmol of creatinine. That of the reference group was 12 nmol of As per mmol of creatinine and significantly below the level of the exposed group (p < 0.001). The arsenic concentration in urine samples from colleagues of the persons working with arsenic containing products was similar to the arsenic concentration in urine samples from the As workers. The concentration of glycosylated haemoglobin (Hgb A1C) was increased in whole blood from the As workers. The level of the As workers was 5.4% (median), similar to that of colleagues (5.5%), while that of the reference group was 4.4%. The differences were significant (p < 0.001). Multiple regression analysis showed a significant connection (p = 0.034) between the concentration of Hgb A1C in whole blood and the arsenic level in urine from the As workers. The systolic blood pressure was 125 mm Hg in the As workers and 117 mm Hg in the control group. The difference was significant (p = 0.023). It is concluded that arsenic exposure has an influence on carbohydrate metabolism, increases the systolic blood pressure and finally may result in increased risk of development of cardiovascular diseases.

Biomonitoring of genotoxic exposure among stainless steel welders.

A biosurvey in the Danish metal industry measured the genotoxic exposure from stainless steel welding. The study comprised measurements of chromosomal aberrations (CA), sister-chromatid exchanges (SCE), unscheduled DNA synthesis (UDS) in peripheral lymphocytes and serum immunoglobulin G. Environmental monitoring of welding fumes and selected metal oxides, biomonitoring of chromium and nickel in serum and urine and mutagenic activity in urine, and evaluation of semen quality were also done. Manual metal arc (MMA) welding and tungsten inert gas (TIG) welding were the dominant welding processes. A higher frequency of chromosomal aberrations, classified as translocations, double minutes, exchanges and rings, was observed in stainless steel welders than in non-welders. SCE was lower in welders working with both MMA and TIG welding than in reference persons. N-Acetoxy-N-acetylaminofluorene (NA-AAF)-induced UDS was lower in 23 never-smoking welders than in 19 unexposed never-smokers. Smoking was a confounding factor resulting in significantly higher CA, SCE, NA-AAF binding to DNA and mutagenic activity in urine. Age was also a confounder: CA, SCE, NA-AAF binding to DNA and UDS increased significantly with age. No significant correlation between SCE and CA or between CA and UDS was found. UDS decreased significantly with increasing lymphocyte count and a higher lymphocyte count was seen in MMA welders than in reference persons and in smokers than in non-smokers. Differences in the composition among lymphocytes in exposed persons compared with non-exposed are suggested. MMA welding gave the highest exposure to chromium, an increased number of chromosomal aberrations and a decrease in SCE when compared with TIG welding. Consequently improvements in the occupational practice of stainless steel welding with MMA is recommended.

Occupational and environmental exposure to arsenic--increased urinary arsenic level in children.

The sum of concentrations of inorganic arsenic, methylarsonic acid (MMAA) and dimethylarsinic acid (DMAA) in urine from adults and children living in an unpolluted area was compared with the corresponding sum measured in urine from adults and children living in an area polluted with arsenic and in urine from persons occupationally exposed to arsenic. The median values for 22 adults and 10 children aged 3-10 years living in the unpolluted area were 9.3 and 19.8 nmol As/mmol creatinine, respectively. The corresponding ranges were 3.2-27.9 and 7.7-57.8 nmol As/mmol creatinine, respectively. The difference between adults and children was tested by Mann-Whitney's non-parametric test and found to be significant (p less than 0.0025). No significant difference was found in arsenic concentration in urine from 73 adults and 10 children living in the polluted area compared with the arsenic concentration in urine from those living in the unpolluted area. The arsenic level in urine from adult workers handling arsenic-treated wood was approximately four-fold higher (p less than 0.001), with a maximum recorded concentration corresponding to 814.9 nmol As/mmol creatinine. The arsenic levels in urine from two glass workers were nine- and two-fold higher, respectively. No significantly increased arsenic levels were found in urine from workers impregnating wood and in urine from lead accumulator workers.

Selenium in chronic neurologic diseases. Multiple sclerosis and Batten's disease.

The selenium levels in whole blood and the activity of glutathione peroxidase in hematogenous cells of normal Danes have been defined taking into account sex and confounding factors such as smoking and aging. No differences related to sex could be found with regard to the selenium level, and peroxidase activity assayed with hydrogen peroxide. However, the peroxidase activity assayed with t-butyl hydroperoxide was higher in females than in males (p less than .05). The peroxidase activities are dependent on age. Thus, the peroxidase levels assayed with both substrates show a minimum value in the age group from 40 to 50 yr for both smokers and nonsmokers. Smokers did show more homogeneous values as a function of age than nonsmokers. Smokers had significantly lower selenium values than nonsmokers, but glutathione peroxidase values identical with those of nonsmokers. Multiple sclerosis (MS) patients suffer from a chronic relapsing/remitting demyelinating disease. A theory explaining the pathogenesis of MS concerns increased stickiness of cellular plasma membranes, hampering normal vascular function of the brain. In agreement with that theory, the present communication demonstrates significantly lowered selenium values and lowered glutathione peroxidase activities of major types of hematogenous cells. In close agreement with these findings, hematogenous cells in MS show increased peroxidation rates. A nonblinded biochemical dietary experiment on MS patients showed that all abnormalities could be normalized by daily intake of selenium, vitamin E, and vitamin C. Batten's disease is a recessive inherited neurodegenerative disorder clinically characterized by progressive loss of vision, epilepsy, and dementia. Neuropathologically, this disease is characterized by storage of lipofuscin in nervous tissue. We have in a few cases documented a low selenium status and low glutathione peroxidase activities of hematogenous cells. As in MS, we normalized the biochemical abnormalities by an antioxidative treatment. Like in similar Finnish studies, the biochemical parameters can be normalized. Further, the Finnish studies indicate it possible by an antioxidative treatment to inhibit progression of the mental deterioration. The data presented will be discussed in relationship both to specific pathological parameters of the diseases and to the low dietary energy expenditures of handicapped immobile patients.

Periodic disklike structures of the adult human loop of Henle. Light and electron microscopic studies.

A total of 51 adult human kidneys was examined for the presence of the periodic disklike thickenings recently described by Belliveau in the basement membrane of the loop of Henle. These "Belliveau bodies" formed a PAS-positive rectangular lattice within the basement membrane and appeared limited to the loop of Henle. The bodies were seen in the medulla of every kidney examined but varied considerably in the frequency of their appearance from case to case. This variability did not correlate with predominant illness, organ weight, or time interval between death and autopsy. They averaged 9 to 14 micron in diameter with a horizontal and vertical periodicity of 12 and 16 micron, respectively. Although the bodies were PAS positive and diastase resistant, they did not stain with Congo red, mucicarmine, reticulin, or elastin staining techniques. Ultrastructurally, they consisted of multilaminated areas of basement membrane material. The constancy of their appearance in the material examined suggests that they are a normal anatomic feature or possibly an age-related change of the basement membrane of Henle's loop in the human kidney.

Gold-associated nephropathy.

Renal biopsy specimens from 11 cases of gold-associated nephropathy were studied by light, immunofluorescence, and electron microscopy. Seven biopsy specimens disclosed the typical glomerular lesions of membranous nephropathy. Four cases disclosed other patterns of glomerular injury, including minimal-change nephrotic syndrome. Although a membranous pattern of immune complex deposition is the most frequent type seen in gold nephropathy, our data indicate that other patterns of immune complex deposition may occur in renal biopsy specimens of patients receiving gold therapy.

Glutathione peroxidase and reductase, glucose-6-phosphate dehydrogenase and catalase activities in multiple sclerosis.

Our previous studies have demonstrated a decreased glutathione feroxidase (GSH-Px) activity of erythrocytes and leucocytes from multiple sclerosis (MS) patients. In the present communication these activities were compared with the activities of associated enzymes (glutathione reductase (GSSG-RD), glucose-6-phosphate dehydrogenase (G-6-PD) and catalase). All enzymic activities were compared between MS patients, other neurologic patients (ON patients) and normal control individuals. Compared to data of ON patients and normal controls, in MS the ratio of GSHPx/GSSGRD in lympho- and granulocytes was significantly decreased (2 alpha less than or equal to 0.05) by 35% and 51%, respectively. The significant correlation between GSSG-RD and the GSH-Px activity (2 alpha less than or equal to 0.05, r = 0.501) found in control lymphocytes was not present in MS lymphocytes. However, the lymphocyte GSH-Px activities of controls as well as of MS correlated with the corresponding serum selenium levels (2 alpha less than or equal to 0.05, r = 0.594 and 2 alpha less than or equal to 0.01, r = 0.967, respectively). The G-6-PD activity was insignificantly increased by 41% in MS lymphocytes compared to normal control. Catalase activity was unchanged in lymphocytes but decreased 50% in MS granulocytes compared to normal control. No significant differences were found between MS and the ON group. The catalase activity of MS erythrocytes was increased by 63% (2 alpha less than or equal to 0.05) in comparison with both the normal control and ON data.

Leucocyte glutathione peroxidase activity and selenium level in Batten's disease.

The glutathione peroxidase (GSHPx) activity was found significantly reduced in whole lymphocytes from patients suffering from Batten's disease. By means of two different procedures for isolation of subcellular fractions of lymphocytes it was possible to demonstrate an increased GSHPx activity of the particulate fractions (20.000 g-av and 105.000 g-av precipitates). However, the GSHPx activity of the supernatants was decreased. The GSHPx activity of the 20.000 g-av supernatant correlated significantly with the serum selenium content both in normal controls and in Batten's disease. A similar correlation was traced with GSHPx activity of erythrocyte haemolysate and serum selenium level in Batten's disease but not in normal controls. The GSHPx activity was also found decreased in the 20.000 g-av and 105.000 g-av supernatants of granulocytes. The abnormal subcellular distribution of GSHPx activities was related to the distribution of enzymes which were used as markers for different subcellular components. The data presented are discussed in relationship to the theory that Batten's disease is due to an increased peroxidation damaging the cellular membranes.

Subcellular distribution of the cytochrome P-450 complex and glutathione peroxidase activity in vitamin E and essential fatty acid deficiency.

Glutathione peroxidase (EC 1.11.1.9.) (GSHPx) and P-450 activity were measured in hepatic mitochondrial and microsomal fractions from rats deficient in vitamin E and/or essential fatty acids (EFA). The data were compared to corresponding normal values. GSHPx was significantly decreased in the mitochondrial matrix from animals in all 3 deficiency states. In vitamin E deficiency, a non-significant decreased GSHPx activity was found in mitochondrial membranes. Opposite to these findings, GSHPx was significantly increased in mitochondrial membranes of EFA-deficient animals. In combined EFA and vitamin E deficiency, the mitochondrial membrane GSHPx activity was only insignificantly increased. The P-450 complex activity was not detectable in the mitochondrial matrix. In mitochondrial membranes and microsomes, the P-450 complex activity changed parallel to the GSHPx activity.

Glutathione peroxidase activity in vitamin e and essential fatty acid-deficient rats.

Gluthathione peroxidase (EC 1.11.1.9, GSHPx) activity was measured in whole liver, in hepatic cytosol and in whole mitochondria from normal rats and from rats subjected to experimentally induced vitamin e and/or essential fatty acid (EFA) deficiency. The animals were fed and raised on the specific diets for 6 months. The GSHPx activity was significantly decreased in all samples of EFA-deficient rats. This group exhibited a significant increased 29:3omega9 content and to low 20:4omega6 content. In rats fed a vitamin E-deficient diet, the GSHP x activity was significantly decreased in hepatic cytosol. When the data of all experimental groups were pooled the specific GSHP x activities of the hepatic cytosol correlated significantly to that of whole mitochondria. The specific GSHP x activity of the whole liver, the mitochondrial and the cytosol fractions were found higher in female than in male rats in controls as well as in deficient animals. This difference was affected by the EFA deficiency. In EFA-deficient mitochondria the sex difference in enzymic activity was decreased (half of normal difference). In EFA-deficient cytosol the difference was increased (double of normal difference). However, the total hepatic GSHPx activities were not significantly higher in female than in male rats in any of the groups studied. Thus, EFA deficiency is added to the list of factors influencing the GSHPx activity. It is concluded that it is not possible to use GSHPx activity as a marker for the selenium status in domestic animals such as suggested previously. Thus, selenium is only one of the factors governing the GSHPx level.

Leucocyte glutathione peroxidase activity and selenium level in multiple sclerosis.

In continuation of our previous studies, which demonstrated a decreased glutathione peroxidase (GSH-Px) activity of erythrocytes from multiple sclerosis (MS) patients the activity of some enzymes regulating the peroxide level (GSH-PX and glutathione reductase (GSSG-Rd)) in leucocytes and erythrocytes respectively, the selenium level of whole blood and the beta-glucuronidase activity of serum (marker of lysosomal membrane damage) were assayed in this group of patients. GSH-Px activity in lymphocytes and granulocytes from MS patients was significantly (2 alpha smaller than or equal to 0.01) decreased by 35-50%. Erythrocyte glutathione reductase activity was only insignificantly decreased in MS patients. Erythrocyte GSH-Px : GSSG-Rd ratio was 11.0 for the control group, but 8.0 for the MS group. The selenium content of whole blood and serum from Danish MS patients was normal. The selenium level in erythrocytes from Danish MS patients was however higher than the selenium level in erythrocytes from controls.

Organochlorine compounds in adipose tissue of Greenlanders and southern Danes.

Abdominal fat tissue samples from the general population of Greenland and from southern Denmark were analyzed for o,p'-DDE and p,p'-DDE [1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene], p,p,-DDT [1,1,1-trichloro-2,2-bis(p-chlorophenyl)-ethane], o,p'-DDT and p,p'-DDD [1,1-dichloro-2,2-bis(p-chlorophenyl)ethane], lindane (1,2,3,4,5,6-hexachlorocyclohexane), aldrin (1,2,3,4,10,10-hexachloro-1,4,4a,5,8,8a-hexahydro-endo-exo-1,4:5,8-dimethanonaphthalene), dieldrin (1,2,3,4,10,10-hexachloro-6,7-epoxy-1,4,4a,5,6,7,8,8a-octahydro-endo-exo-1,4:5,8-dimethanonaphthalene), heptachlor (1,4,5,6,7,8,8-heptachloro-3a,4,7,7a-tetrahydro-4,7-methanoindene), heptachlor epoxide, and polychlorinated biphenyls (PCBs). Fat tissue from Greenlanders contained significantly higher amounts of p,p'-DDE (p less than or equal to 0.05), p,p'-DDT (p less than or equal to 0.01), and total DDT (SIGMA DDT, the sum of DDT and its metabolites) (p less than or equal to 0.01) than southern Danes. Lindane, aldrin-like residue, dieldrin heptachlor-like residue, heptachlor epoxide, and PCBs were present in adipose tissue of both groups and there were no significant differences between the groups. The p,p'-DDE level in Greenland was lower than that in the United States, eastern Europe, and India. Among Greenlanders of different ages the highest sigma DDT was found in the age group of 22-45 yr; the content of PCBs increased with age. Among southern Danes the highest sigma DDT was found in a higher age group than in Greenlanders. Among Greenlanders the content of aldrin-like residue decreased with age and that of dieldrin increased with age. A significant correlation was found (on the basis of wet weight) between p,p'-DDE and PCB content in southern Danes (p less than or equal to 0.02). The correlation between sigma DDT and PCB content was also significant in this population (p less than or equal to 0.01). These two relationships were not significantly correlated for the Greenlanders. The DDE/PCB and sigma DDT/PCB ratios were higher in Greenlanders than in southern Danes. These ratios are age-dependent and are highest in the age group 22-45 yr among the Greenlanders. A low DDE/PCB ratio and a low sigma DDT/PCB ratio have been proposed as markers for industrialization. In Greenlanders p,p'-DDE represented about 70% of sigma DDT. For southern Danes this level was about 90%. The data obtained are presented and discussed on the basis of both lipid and wet weight levels.

Serum fatty acids and peroxidase abnormalities in Batten's disease.

The linoleic acid content of serum lipids was measured in 10 paitents with Batten's disease and 11 healthy control subjects by gas liquid chromatography. The fatty acid patterns of serum lipids in this disease may reflect a primary or secondary deficiency in essential fatty acid (linoleic acid) probably related to a glutathione peroxidase abnormality.

Biochemical abnormalities in Batten's syndrome.

The present data indicate that a group of ten patients with Batten's syndrome showed reduced activity of erythrocyte glutathione (GSH) peroxidase (Px) (glutathione: H2O2 oxidoreductase, EC 1.1.1.9.) using H2O2 as peroxide donor. Assay of erythrocyte GSHPx using H2O2, cumene hydroperoxide and t-butyl hydroperoxide as donors also makes it possible biochemically to divide Batten's syndrome into two types: (1) one type with decreased values when H2O2 and cumene hydroperoxide are used, and (2) one type with increased values when t-butyl hydroperoxide is used. Furthermore an increased content of palmitic, oleic and of eicosatrienoic acid but decreased linoleic acid content was found in serum from patients with Batten syndrome. An inverse relationship between erythrocyte GSHPx and serum eicosatrienoic acid was found in the patients. Finally normal selenium levels were found in erythrocytes, but decreased values were traced in whole blood. In normal human beings a connection was found between the erythrocyte selenium content and GSHPx activity assayed by cumene hydroperoxide as a peroxide donor.