Radon in dwellings

Summary Whereas lung cancer mortality surveys in French departments obviously demonstrate the effect of smoking or of living in strongly industrialized areas, the same survey does not give evidence of lung cancer deaths increases in the departments where the radon concentrations in dwellings are the highest.     

Radon in dwellings: The importance of ventilation

Summary People who live in industrial countries receive a radioactive dose of 2.4 mSv/y: the most important contribution to this dose is given by radon decay products. Radon is a noble gas generated from the disintegration of radium, which is found in soils and building materials. Owing to a bad air circulation, radon and its daughters may accumulate in a house. By using a mathematical model it may be shown that radon concentration is inversely proportional to the ventilation rate. Measurements of radon concentration through the method of activated carbon canisters, show that in a room with a double-pane window, kept continuously closed, the mean radon concentration can exceed the concentration of a similar room with a single-pane window of 190%. However, the radon concentration inside the energy-saving room may be decreased up to values slightly higher than those measured in the conventional window room, by simply opening the double-pane window a few minutes a day. A set of measurements carried out in a group of house in Reggio Emilia validates the effectiveness of that practice: radon concentrations in rooms with double-pane window closely approximated to those of rooms with ordinary window.     

Radon survey in dwellings of Gansu,China: the influence of thoron and an attempt for correction

Alpha track detectors used in a previous investigation of the US National Cancer Institute and the China Ministry of Health on indoor radon ((222)Rn) in Gansu, China, proved to be influenced by (220)Rn (thoron), thus overestimating the (222)Rn level. Therefore, the detector was improved used in the previous survey. The new detectors allow discrimination between the two isotopes without any disturbance of the (222)Rn measurement. With this detector, a semi-annual study was conducted in 49 traditional dwellings of a village in Gansu. The arithmetic (AM) and geometric (GM) mean (222)Rn concentrations were 120 +/- 61 and 105 Bq m(-3) (with geometric standard deviation GSD = 1.8), respectively, while the mean (220)Rn concentrations at 2.5 cm wall distance were 430 +/- 210 Bq m(-3) (AM) and 350 Bq m(-3) (GM) with GSD = 2.3. The high thoron concentrations demonstrate the importance of the (220)Rn contribution to radiation exposure, in the investigated area. The actual level of indoor (222)Rn was about three times lower than that in the previous investigation which was affected by (220)Rn. A correction method for the radon results of the previous study is proposed, which provides (222)Rn and (220)Rn values comparable with those obtained in the study presented here.     

Genetical and epidemiological studies of polydactyly in Hungary

Polydactyly is one of the most frequently observed human congenital limb malformations. Sporadic cases of polydactyly have been described, but most show an autosomal dominant pattern of inheritance. The purpose of this study was to investigate the frequency of polydactyly among children born between 1980 and 1997 in Hungary. The predominance of the postaxial type over the preaxial one was less than expected. These malformations affected significantly more boys than girls. The proportion of children with low birth weight affected by polydactyly was higher than expected. Among mothers giving life to offspring with polydactyly, the prevalence was high in the older age group. We analysed the regional distribution in Hungary and the twin frequency in connection with polydactyly. From our results comparing it to the current literature data we made conclusions about the possible causes of the development of polydactyly.     

Genetic and epidemiological studies in Dagestan highland isolates

Interpopulation differences in the epidemiology and age of onset of complex diseases, as well as expression of some vital parameters, have been found. The relationship between these interpopulation differences and the genetic processes that have been occurring in the populations throughout their history has been demonstrated. The Daghestan genetic isolates studied are characterized by aggregation of certain complex diseases. In each genetic isolate, almost all affected subjects with homogeneous clinical phenotypes belong to the same large pedigree with a limited number of founders. There is evidence for a large variance of the population risk of schizophrenia (morbid risk) in Daghestan isolates (this parameter varies from 0 to 5%). Examination of 211 cases of schizophrenia earlier diagnosed in Daghestan psychiatric hospitals has shown that only 139 of them meet the DSM-IV criteria for schizophrenia. The remaining 72 subjects have, according to DSM-IV criteria, various schizoaffective and affective disorders; all of these subjects are close relatives of the schizophrenic patients. The age of onset of schizophrenia in the isolates studied varies from 14 to 40 years (20.84 +/- 0.568 years). Offspring of consanguineous marriages exhibit later age at onset and a higher risk of schizophrenia than offspring of exogamous marriages. The results of multivariate genetic analysis indicate that different gene complexes are involved in the pathogeneses of early-onset and late-onset forms of schizophrenia. An association of schizophrenia incidence, its age dependence, and reproductive parameters with polymorphisms of some microsatellite loci have been demonstrated.     

Lymphocyte antigens in Norwegian goats: serological and genetic studies

Altogether, 292 goat alloantisera were screened for antilymphocyte reactivity in a two-step dye exclusion microcytotoxicity test. Fifteen different lymphocyte antigen specificities were characterized by cluster analysis and absorption studies. The specificities were designated N1-N15 (N for Norwegian). Lymphocytes from 247 Norwegian dairy goats were tested. Each animal displayed from none to four of the characterized specificities. Lysostrip testing and family studies indicated that the specificities N1-N14 were coded for by multiple alleles belonging to at least two closely linked loci. It is suggested that these loci are part of the caprine major histocompatibility complex. Family studies gave strong evidence that the specificity N15 was not coded for by genes located in the same region as the other 14 specificities. Absorption studies showed that this specificity was located on both lymphocytes and erythrocytes.     

Ecological and epidemiological studies of histoplasmosis in the United States of America

Histoplasmosis is a disease that is transmitted from nature to man. The causative agent,Histoplasma capsulatum, grows freely in the soil and the infection is spread by inhalation of the infectious spores. The infection is highly endemic in the central United States. Soil contaminated with fecal droppings of chickens, starlings, blackbirds, and other avian species is a principal source of infection.Paper read at the Eighth International Congresses for Tropical Medicine and Malaria, September 1968, Teheran (Iran).     

Importance of allele frequency estimates in epidemiological studies

This study addresses the issue of appropriate allelic frequency estimates in epidemiological studies. Reasons for imprecise estimate of allele frequency may be population stratification, and lack of power of many published studies to define true allele frequencies in the general population. As an example of the lack of power of epidemiological studies, we plot the frequency of GSTM1 deletion versus sample size for the 79 studies from the GSEC pooled analysis. The estimate of allele frequency derived from small groups of controls deviates more from the true frequency than the estimate derived from larger studies. We discuss the possible consequences of not properly defining allele frequencies in the population. This may reflect on the conduct of association studies, on assessment of the effects of multigenic mechanisms, and on the determination of genetic diversity.     

Exposure classification of MRI workers in epidemiological studies

We estimate that there are about 100,000 workers from different disciplines, such as radiographers, nurses, anesthetists, technicians, engineers, etc., who can be exposed to substantial electromagnetic fields (compared to normal background levels) around magnetic resonance imaging (MRI) scanners. There is a need for well‐designed epidemiological studies of MRI workers but since the exposure from MRI equipment is a very complex mixture of static magnetic fields, switched gradient magnetic fields, and radiofrequency electromagnetic fields (RF EMF), it is necessary to discuss how to assess the exposure in epidemiological studies. As an alternative to the use of job title as a proxy of exposure, we propose an exposure categorization for the different professions working with MRI equipment. Specifically, we propose defining exposure in three categories, depending on whether people are exposed to only the static field, to the static plus switched gradient fields or to the static plus switched gradient plus RF fields, as a basis for exposure assessment in epidemiological studies. Bioelectromagnetics 34:81–84, 2013. © 2012 Wiley Periodicals, Inc.     

Hyper-insulinaemia and cancer, meta-analyses of epidemiological studies

BACKGROUND: A substantial body of evidence links sex hormones, diet, excess body weight and physical activity to the risk of developing cancer at several sites common in affluent countries. The hypothesis that high circulating levels of insulin could be the underlying factor increasing cancer risk has been proposed. Epidemiological studies on markers of hyper-insulinaemia and cancer are reviewed and summarized. METHODS: Studies of cancers of the colon and rectum, pancreas, breast, and endometrium examining the association with blood levels of C-peptide, insulin, glucose, glycated haemoglobin (HbA1c) were searched in PubMed. Multivariate, adjusted relative risks (RR) and their 95% confidence intervals were abstracted and summarized by meta-analyses. RESULTS: Most of the studies identified were cohorts that relied on measurements obtained at baseline or assessed in blood stored at low temperature several years before the onset of cancer. The meta-analyses showed excess risks of colorectal and pancreatic cancers associated with higher levels of circulating C-peptide/insulin and with markers of glycaemia. Significant heterogeneity was found among four epidemiological studies of endometrial cancer and C-peptide giving a summary RR compatible with no association. Overall breast cancer risk was significantly higher in the upper categories of C-peptide/insulin, however, the excess derived entirely from retrospective studies. CONCLUSION: Current evidence suggests that subjects who develop colorectal and pancreatic cancers have increased pre-diagnostic blood levels of insulin and glucose.     

Erythrocyte antigens in Norwegian goats: serological and genetic studies.

Goat alloantisera and bovine blood typing reagents were used to characterize eight erythrocyte antigen specificities in Norwegian goats by cluster analysis, absorption and family studies. Most of the goat sera were produced by injecting dams once or twice with blood cells or blood from their own kids. The characterized specificities were designated N1-N8. The two specificities N5 and N8 were recognized both by goat alloantisera and by reagents against the bovine factors E'1 and E'2 (N5) and I (N8), which are allelic factors in the bovine B-system. In goat families, the two specificities also behaved as alleles. Consequently, the locus or gene system coding for these specificities was called the B-system of goats. The six other erythrocyte antigens were provisionally assigned to six separate loci. In addition, a bovine anti-sheep R factor reagent reacted with cells from 3.3% of the goats tested, whereas a monoclonal antibody against the Forssman antigen reacted with all the goats tested.     

Dopamine receptor binding in vivo: the feasibility of autoradiographic studies

Several minutes after the injection of small quantities of ³H-spiroperidol into the tail vein of the rat, radioactivity in the brain exhibited the characteristics of a major association with dopamine receptors. These characteristics included: a regional distribution paralleling that of dopamine receptors; saturability; an appropriate pharmacology in that only dopaminergic drugs blocked the accumulation; lack of metabolism of ³H-spiroperidol. Autoradiographs revealed a great density of ³H-spiroperidol binding sites in the neuropil of the striatum, nucleus accumbens and olfactory tubercle, all areas receiving a dopaminergic input. Other areas without such an input exhibited background levels of autoradiographic grains.     

Challenges and recommendations for conducting epidemiological studies in the field of epilepsy pharmacogenetics

Epilepsy is one of the most prevalent neurological disorders, afflicting approximately 50 million Indians. Owing to affordability and easy availability, use of first-generation antiepileptic drugs (AEDs) is heavily encouraged for the treatment of epilepsy in resource-limited countries such as India. Although first-generation AEDs are at par with second-generation AEDs in terms of efficacy, adverse drug reactions (ADRs) are quite common with them. This could be attributed to the inferior pharmacokinetic parameters such as nonlinear metabolism, narrow therapeutic index and formation of toxic intermediates. In addition, epilepsy patients may differ in the pharmacokinetic and pharmacodynamic profiles, with about 1/3(rd) of the population failing to respond to treatment. A proportion of this interindividual variability in response may be explained by genetic heterogeneity in the activity and expression of the network of proteins such as metabolizing enzymes, transporters and targets of AEDs. Over the last two decades, a considerable effort has been made by the scientific community for unraveling this genetic basis of variable response to AEDs. However, there have been inconsistencies in such genetic association studies conducted across different territories of the world. There could be several reasons underlying the poor replicability of these studies, mainly nonuniform phenotypic definitions, poor sample size and interethnic variability. In the present review article, we provide an overview of heterogeneity in study designs for conducting pharmacogenetic studies. In addition, critical recommendations required for overcoming such challenges imposed by pharmacogenetic epidemiological studies have been briefly discussed.     

Cognitive impairment and oxidative stress in the elderly: results of epidemiological studies

Cognitive impairment is a major component of age-related dementing diseases and it has been suggested that it could share the same pathological pathways with neurodegenerative processes and cerebrovascular lesions. The free radical theory of ageing could be one of these pathways. Implication of free radical damage in processes related to cerebral ageing is a good argument in favour of the hypothesis that antioxidants may protect against cognitive impairment. Observational studies (mostly cross-sectional) of relationships between cognitive impairment and antioxidant status are based on the evaluation of dietary intake or on the levels of carotenoids, selenium and vitamins A, C and E in plasma or red blood cells. More convincing results were obtained on vitamin C and carotenoids. Despite some limitations, the comparison between results obtained in various populations is becoming increasingly informative and these studies argue for a protective effect of antioxidants on cognitive performance.     

Genetic and epidemiological studies on electrolyte transport systems in hypertension

In recent years several different tests of cations in human cells have been studied to detect and to define possible roles in the development of essential hypertension. The goal of this report is to summarize what has been learned in genetic and epidemiological studies of human populations. The seven tests reviewed in greatest detail include sodium-lithium countertransport, intraerythrocytic sodium, sodium (or lithium)-potassium cotransport, lithium leak, sodium-potassium ATPase pump, sodium pump sites (ouabain binding), and circulating sodium pump inhibitor ('digoxin-like factor' in some studies). Countertransport, intraerythrocytic sodium and cotransport consistently show different values in hypertensives compared to normotensives and even in normotensives with a positive family history of hypertension when compared to controls without a positive family history. Thorough genetic studies have been carried out only for sodium-lithium countertransport and intraerythrocytic sodium. Both of these tests are highly heritable with a combination of both polygenic and major gene effects. Cotransport, leak, and pump sites also seem to be quite significantly heritable whereas the ATPase pump activity and the circulating pump inhibitor seem to be largely determined by nongenetic factors. Some of the most dramatic changes in these tests have been observed during pregnancy. Significant increases are seen in countertransport, cotransport, ouabain binding sites, and digoxin-like factor. Oral contraceptives also seem to affect at least cotransport. Plasma triglyceride level and body weight are some of the strongest correlates of countertransport, cotransport, and lithium leak. Cotransport increases with higher dietary sodium intake and decreases with the use of the diuretic medication. In the current developmental stage these tests have several significant limitations. In most population studies there is a considerable overlap of test values between persons with high and normal blood pressure. There are substantial variations in the methods used by different laboratories for the same tests. They are expensive, complex and usually must be done on fresh cells. There are conflicts between the results of several different reported studies that could be due to the way in which their subjects were selected, the effects of medications or other uncontrolled variables, or even due to the differences in laboratory methodologies.(ABSTRACT TRUNCATED AT 400 WORDS)