Chronic fluoride toxicity decreases the number of nicotinic acetylcholine receptors in rat brain

In order to investigate the molecular mechanism(s) underlying brain dysfunction caused by chronic fluorosis, neuronal nicotinic acetylcholine receptors (nAChRs) in the brain of rats receiving either 30 or 100 ppm fluoride in their drinking water for 7 months were analyzed in the present study employing ligand binding and Western blotting. There was a significant reduction in the number of [³H]epibatidine binding sites in the brain of rats exposed 100 ppm of fluoride, but no alteration after exposed to 30 ppm. On the other hand, the number of [¹²⁵I]-BTX binding sites was significantly decreased in the brains of rats exposed to both levels of fluoride. Western blotting revealed that the level of the nAChR 4 subunit protein in the brains of rats was significantly lowered by exposure to 100 ppm, but not 30 ppm fluoride; whereas the expression of the 7 subunit protein was significantly decreased by both levels of exposure. In contrast, there was no significant change in the level of the β2 subunit protein in the brains of rats administered fluoride. Since nAChRs play major roles in cognitive processes such as learning and memory, the decrease in the number of nAChRs caused by fluoride toxicity may be an important factor in the mechanism of brain dysfunction in the disorder.     

Detection and characterization of a novel functional polymorphism in the GSTT1 gene

A novel functional polymorphism in the GSTT1 gene associated with the non-conjugator phenotype has been identified. Sequencing of GSTT1 cDNA revealed a single nucleotide substitution, 310A>C, that altered the amino acid residue 104 from threonine to proline (T104P). Modelling studies of GSTT1 have suggested that residue 104 is located in the middle of alpha-helix 4. Introduction of an alpha-helix-disrupting proline most likely distorts the conformation of the protein. Individuals that lacked GSTT1 activity and carried the variant allele, tentatively denoted GSTT1*B, had no detectable GSTT1 immunoreactive protein. An allele-specific polymerase chain reaction method was developed to determine the frequency of the GSTT1*B allele. In 497 ethnic Swedes, the frequency of the active GSTT1*A allele was 0.65 [95% confidence interval (CI) 0.62-0.68] whereas the frequencies of the non-functional alleles GSTT1*O and the novel GSTT1*B allele were 0.34 (CI 0.31-0.37) and 0.01 (CI 0.01-0.02), respectively. In 100 Swedish Saamis, the GSTT1*B allele appeared to be slightly more common with a frequency of 0.03 (CI 0.01-0.07). The GSTT1 enzyme activity was measured in erythrocytes using methyl chloride as substrate. Individuals with the GSTT1*A/*A genotype had a two-fold higher GSTT1 activity compared to individuals with the GSTT1*A/*B genotype and subjects with the GSTT1*O/*B genotype totally lacked GSTT1 activity, indicating a strict gene-dose effect. By combining the analyses for the novel single nucleotide polymorphism with analyses for the deletion polymorphism, the accuracy in predicting all three GSTT1 conjugator phenotypes was improved from 96% to 99%.     

A quantitative real-time PCR method for tissue factor mRNA

BACKGROUND: Tissue factor (TF) is primarily known for its function to initiate blood coagulation. The range of in vivo expression of TF is wide and requires a dynamic assay for monitoring. A general method for TF mRNA quantitation that is dynamic, sensitive and applicable to a variety of experimental systems or clinical situations is therefore desirable. OBJECTIVES: To develop a method for sensitive and dynamic quantitation of TF mRNA in human blood cells. METHODS: TF mRNA expression was analysed and evaluated in monocyte isolations, in whole blood (healthy volunteers and patients scheduled for percutaneous coronary intervention, PCI) and in a panel of human cell lines. RNA was extracted, reverse transcribed and subjected to real-time PCR amplification, according to the TaqMan technology. A TF plasmid was constructed as calibrator of the assay. Two housekeeping genes used as endogenous controls for cDNA quality and integrity were evaluated. RESULTS: The assay was linear by seven orders of magnitude and detected down to 10(2) copies of the TF plasmid. The coefficient of variation was 4% intra-assay and 28% between the assays when using beta2MG as endogenous control. The beta-actin gene expression was induced by treatment with lipopolysaccharide (LPS) in blood leukocytes and could not be used as an endogenous control. However, beta2MG showed only minor variations upon treatment with LPS. The TF mRNA and antigen expression, measured in a Western blot, correlated well (R(2)=0.903) in a panel of 11 human cell lines. CONCLUSIONS: We have established a method for sensitive and dynamic quantitation of TF mRNA in experimental systems and for clinical situations.     

Influence on coagulation activity by subcutaneous LMW heparin as an adjuvant treatment to fibrinolysis in acute myocardial infarction

In this study, which includes 101 patients with acute ST segment-elevated myocardial infarction, we investigated the influence on the increased coagulation activity after streptokinase treatment by adding low-molecular-weight (LMW) heparin or placebo and the relation between the coagulation activity and ischemic episodes, coronary patency, and mortality. The expected increase of prothrombin fragment 1+2 (F1+2), thrombin-antithrombin (TAT), and D-dimer were significantly attenuated at 2, 6, and 18 h (D-dimer only at 18 h) in the dalteparin group compared to placebo. Ischemic episodes during the first 24 h appeared significantly more often in patients with F1+2 levels above the median at 18 h. There was a tendency to a lower frequency of Thrombolysis In Myocardial Infarction Trial (TIMI) grade 3 flow in the infarct-related artery in patients with TAT and D-dimer levels above the median at 18 h. F1+2, TAT, and D-dimer were significantly higher after 18, 6, and 18 h, respectively, in the deceased compared to surviving patients. Also, the lack of reduction of the levels of F1+2 between 6 and 18 h was related to a raised mortality. In conclusion, adjuvant treatment with LMW heparin to streptokinase attenuates increased coagulation activity. This might be of importance as remaining high coagulation activity is associated with signs of early reocclusion and raised mortality.     

Early diagnosis of Alzheimer disease with positron emission tomography

The emergence of drugs that may slow progression of Alzheimer disease, if administered early during its course, has necessitated early diagnosis of the disease itself. Among the functional imaging methods that could assist in early diagnosis, positron emission tomography has an important role in providing quantitative measures of various aspects of brain function affected by the disease. Positron emission tomography studies in patients with Alzheimer disease have revealed a typical pattern of metabolic deficits in the temporal and parietal lobes. Additionally, converging evidence from numerous studies indicates that a similar pattern of deficits can be observed in nondemented subjects who are at risk of developing the disease, such as those with recognized genetic traits such as familial Alzheimer disease with mutations in chromosomes 21 and 14, Down syndrome, subjects with the epsilon4 allele of the apolipoprotein E gene, and individuals with mild cognitive impairment. These findings might have implications for the selection of patients for clinical trials, defining the outcome measures and evaluation of treatment efficacy and responder characteristics, but should be confirmed by prospective studies comprising larger samples and include clinicopathologic correlations.     

SIOP working committee on psychosocial issues in pediatric oncology

Recognizing the importance of psycho-social issues in the care and cure of the child with cancer, the board of the International Society of Pediatric Oncology (SIOP) in 1991 constituted a Working Committee on Psychosocial Issues in Pediatric Oncology, with Giuseppe Masera as chair and John Spinetta as co-chair. This committee met for the first time in Rhodes, Greece, in October 1991. The committee discussed various psychosocial issues and developed a document on Aims and Recommendations, summarizing the experiences of major centers. This document was approved by the SIOP board, which recommended diffusion of the document to the pediatric oncology community. © 1993 Wiley-Liss, Inc.     

A study on skin tumour formation in mice with 50 Hz magnetic field exposure

In order to test the possibility that magnetic fields (MF) actas a tumour promoter, a long-term skin carcinogenicity studyof 50 Hz sinusoidal MF with flux densities of 50 µT and0.5 mT was performed in female NMRI mice. 7, 12–dimethylbenz[a]anthracene(DMBA) in acetone was applied to the dorsal skin, as an initiator,and exposure to MF was performed for 19 (weekdays) or 21 h/day(weekends and holidays) for 103 weeks starting one week afterthe initiator treatment. The phorbol ester 12–O–tetradecanoylphorbol-13-acetate(TPA) was used as a positive control for skin tumour promotingactivity. MF was also evaluated for complete carcinogenic actionin groups of mice that were treated with acetone only. Six animalsfrom each group were taken for skin hyperplasia analysis andwere killed after 9, 26 and 52 weeks. The appearance of skinlesions were carefully followed and histopathological diagnosiswas made for all neoplasms present at death. The statisticalanalyses on occurrence of skin tumour bearing animals and cumulatedskin tumours, with corrections for survival, did not reveala difference between the controls and the MF exposed groups.The epithelial thickness of DMBA + MF-treated animals was ofthe same magnitude as for DMBA-treated animals. Leukaemia wasa little more frequent among animals exposed to 0.5 mT MF comparedto the control animals. However this difference was not statisticallysignificant.     

Screening for minimal brain dysfunction (MBD/DAMP) at six years of age: results of motor test in relation to perinatal conditions, development and family situation

The aim of this study was to investigate if children aged 6 years of age, classified as having minimal brain dysfunction (MBD) or deficit in attention, motor control and perception (DAMP), exhibit special medical problems, specific developmental features or if special psychosocial conditions exist in the family. The screening program, using the psychoneurological part of the method developed by Gillberg et al., included 234 children who were followed-up prospectively from pregnancy and birth. The results were related to the physical and mental development of the children, to the psychosocial and socioeconomic conditions of the families, to pre- and postnatal conditions and to “reduced optimality score”, as defined by Prechtl. Mental development was assessed by the use of Griffiths' test at 10-14 months and at 4-5 years of age. At the second Griffiths' test, the mother was also interviewed about the presence of aggressiveness and other symptoms of childhood psychopathology in her child, as defined by the DSM-III criteria, and a psychological observation was also made. In addition to screening for MBD/DAMP, at 6 years of age the parents were asked to complete a questionnaire aimed at identifying attention deficit disorder (ADD). No medical or psychological intervention was made before this stage. Fourteen children (9M, 5F) (6%) were identified as having a positive MBD/DAMP screening result. The results of the screening procedure showed a weak correlation with those obtained using the questionnaire based on the DSM-III criteria for ADD. Compared with the rest of the children, those with a positive MBD/DAMP screening result had an increased number of complications during pregnancy but not a reduced optimality score. At 4 years of age the performance on the Griffiths' test was lower and the rate of child psychiatric symptoms such as aggressiveness and signs of the mother having difficulties in setting limits for the child were more common than among the rest of the cohort. No relation was found with the psychosocial or socioeconomic conditions of the family. We conclude that children suspected of having MBD/DAMP at the start of school may have exhibited signs of delayed psychoneurological development and symptoms of psychopathology at 4 years of age.