Genetic time-series analysis identifies a major QTL for in vivo alcohol metabolism not predicted by in vitro studies of structural protein polymorphism at the ADH1B or ADH1C loci

After ingestion of a standardized dose of ethanol, alcohol concentrations were assessed, over 3.5 hours from blood (six readings) and breath (10 readings) in a sample of 412 MZ and DZ twins who took part in an Alcohol Challenge Twin Study (ACTS). Nearly all participants were subsequently genotyped on two polymorphic SNPs in the ADH1B and ADH1C loci known to affect in vitro ADH activity. In the DZ pairs, 14 microsatellite markers covering a 20.5 cM region on chromosome 4 that includes the ADH gene family were assessed, Variation in the timed series of autocorrelated blood and breath alcohol readings was studied using a bivariate simplex design. The contribution of a quantitative trait locus (QTL) or QTL's linked to the ADH region was estimated via a mixture of likelihoods weighted by identity-by-descent probabilities. The effects of allelic substitution at the ADH1B and ADH1C loci were estimated in the means part of the model simultaneously with the effects sex and age. There was a major contribution to variance in alcohol metabolism due to a QTL which accounted for about 64% of the additive genetic covariation common to both blood and breath alcohol readings at the first time point. No effects of the ADH1B*47His or ADH1C*349Ile alleles on in vivo metabolism were observed, although these have been shown to have major effects in vitro. This implies that there is a major determinant of variation for in vivo alcohol metabolism in the ADH region that is not accounted for by these polymorphisms. Earlier analyses of these data suggested that alcohol metabolism is related to drinking behavior and imply that this QTL may be protective against alcohol dependence.

Molecules and morphology in phylogenetic studies of the Hemiuroidea (Digenea : Trematoda : Platyhelminthes)

Phylogenies of trematodes based on characters derived from morphology and life cycles have been controversial. Here, we add molecular data to the phylogenetic study of a group of trematodes, members of the superfamily Hemiuroidea Looss, 1899. DNA sequences from the V4 domain of the nuclear small subunit (18S) rRNA gene and a matrix of morphological characters modified from a previous study were used. There was no significant incongruence between the molecular and the morphological data. However, this was probably due largely to the limited resolving power of the morphological data. Analyses support a monophyletic Hemiuroidea containing at least the families Accacoeliidae, Derogenidae, Didymozoidae, Hirudinellidae, Sclerodistomidae, Syncoeliidae, Isoparorchiidae, Lecithasteridae, and Hemiuridae. These families fall into two principal clades. One contains the first six families and the other the Hemiuridae and lecithasterine lecithasterids. The positions of the hysterolecithine lecithasterids and the Isoparorchiidae were poorly resolved. The Ptychogonimidae may be the sister group of the remaining Hemiuroidea, but there was no support from the molecular data for the placement of the Azygiidae within the superfamily. (C) 1998 Academic Press.

Mild myocardial infarction - A classification problem in epidemiologic studies

In studies assessing the trends in coronary events, such as the World Health Organization (WHO) MONICA Project (multinational MONItoring of trends and determinants of CArdiovascular disease), the main emphasis has been on coronary deaths and non-fatal definite myocardial infarctions (MI). It is, however, possible that the proportion of milder MIs may be increasing because of improvements in treatment and reductions in levels of risk factors. We used the MI register data of the WHO MONICA Project to investigate several definitions for mild non-fatal MIs that would be applicable in various settings and could be used to assess trends in milder coronary events. Of 38 populations participating in the WHO MONICA MI register study, more than half registered a sufficiently wide spectrum of events that it was possible to identify subsets of milder cases. The event rates and case fatality rates of MI are clearly dependent on the spectrum of non-fatal MIs, which are included. On clinical grounds we propose that the original MONICA category ''non-fatal possible MI'' could bt:divided into two groups: ''non fatal probable MI'' and ''prolonged chest pain.'' Non-fatal probable MIs are cases, which in addition to ''typical symptoms'' have electrocardiogram (EGG) or enzyme changes suggesting cardiac ischemia, but not severe enough to fulfil the criteria for non-fatal definite MI In more than half of the MONICA Collaborating Centers, the registration of MI covers these milder events reasonably well. Proportions of non-fatal probable MIs vary less between populations than do proportions of non fatal possible MIs. Also rates of non-fatal probable MI are somewhat more highly correlated with rates of fatal events and non-fatal definite MI. These findings support the validity of the category of non-fatal probable MI. In each center the increase in event rates and the decrease in case-fatality due to the inclusion of non-fatal probable MI was lar er for women than men. For the WHO MONICA Project and other epidemiological studies the proposed category of non-fatal probable MIs can be used for assessing trends in rates of milder MI. Copyright (C) 1997 Elsevier Science Inc.

Adjusting for fat-free mass in metabolic studies

in a recent publication, Eriksson et al. [1] explored the relationship between size at birth and resting metabolic rate and body composition in adulthood in a cohort of over 300 men and women. They reported an unexpected finding that people of both sexes who had a low birth weight also had a higher metabolic activity per unit muscle tissue. This conclusion was drawn from an analysis where resting metabolic rate (expressed as kcal/kg fat-free mass) in adulthood was examined relative to the birth weight of the subject. One explanation that they suggested was that the apparent increased activity of muscle tissue resulted from an increased sympathetic drive associated with low birth weight. There may be a less physiological reason for the findings of Eriksson et al. Whilst the data are not given specifically in the text, it can be seen clearly from Fig. 1 in the paper that the mean fat-free mass measured in adulthood increased, in both sexes, from the lightest birth weight group to the heaviest birth weight group when the cohort were divided into tertiles based on birth weight. The crux of the issue is that in many - indeed most - cases, expressing resting energy expenditure as kcal/kg fat-free mass does not totally adjust for fat-free mass [2 - 5], and a bias is introduced so that those who have a higher fat-free mass will tend to have a lower resting energy expenditure when expressed per kg fat-free mass. This bias found when expressing many physiological parameters relative to body size, body weight or body composition has long been known [6], and should be carefully considered by appropriate adjustment and hence analysis.

The Mallory body as an aggresome: In vitro studies

Prior in vivo studies supported the concept that Mallory bodies (MBs) are aggresomes of cytokeratins 8 and 18. However, to test this hypothesis an in vitro model is needed to study the dynamics of MB formation. Such a study is difficult because MBs have never been induced in tissue culture. Therefore, MBs were first induced in vivo in drug-primed mice and then primary cultures of hepatocytes from these mice were studied. Two approaches were utilized: 1. Primary cultures were transfected with plasmids containing the sequence for cytokeratin 18 (CK 18) tagged with green fluorescent protein (GFP). 2. Immunofluorescent staining was used to localize the ubiquitin-proteasome pathway components involved in MB-aggresome complex formation in primary hepatocyte cultures. The cells were double stained with a ubiquitin antibody and one of the following antibodies: CK 8, CK 18, tubulin, mutant ubiquitin (UBB+ 1), transglutaminase, phosphothreonine, and the 20S and 26S proteasome subunits P25 and Tbp7, respectively. In the first approach, fluorescence was observed in keratin filaments and MBs 48 h after the cells were transfected with the CK 18 GFP plasmid. Nascent cytokeratin 18 was preferentially concentrated in MBs. Less fluorescence was observed in the normal keratin filaments. This indicated that MBs continued to form in vitro. The immunofluorescent staining of the hepatocytes showed that CK 8 and 18, ubiquitin, mutant ubiquitin (UBB+ 1), P25, Tbp7, phosphothreonine, tubulin, and transglutaminase were all located at the border or the interior of the MB. These results support the concept that MBs are aggresomes of CK 8 and CK 18 and are a result of inhibition of the ubiquitin-proteasome pathway of protein degradation possibly caused by UBB+ 1. (C) 2002 Elsevier Science.

A rapid method for determining recent sunscreen use in field studies

The role of sunscreens in preventing skin cancer and melanoma is the focus of ongoing research. Currently, there is no objective measure which can be used in field studies to determine whether a person has applied sunscreen to their skin, and researchers must use indirect assessments such as questionnaires. We sought to develop a rapid, non-invasive method for identifying sunscreen on the skin for use in epidemiological studies. Our basic method is to swab the skin, elute any residues which have been adsorbed onto the swab by rinsing in ethanol, and submit the eluted washings for spectrophotometric analysis. In a controlled study, we applied 0.1 ml of sunscreen to a 50 cm(2) grid on both forearms of 21 volunteers. Each forearm was allocated one of 10 different sunscreen brands. The skin was swabbed after intervals of 20 min, 1 h, 2 h and 4 h. In a field study conducted among 12 children aged 2-4 years attending a child care centre, sunscreen was applied to the faces of half the children. Swabs were then taken from the face and back of all children without knowledge of sunscreen status. In the controlled study, sunscreen was clearly detectable up to 2 h after application for all brands containing organic sunscreen, and marginally detectable at 4 h. In the field study, this method correctly identified all children with and without sunscreen. We conclude that spectrophotometric analysis of skin swabs can reliably detect the presence of sunscreen on the skin for up to 2 It after application. (C) 2002 Elsevier Science B.V. All rights reserved.

In situ studies on service life and pick consumption characteristics of shearer drums

Longwall shearers usually suffer from excessive pick and pickholder consumptions and severe wear of the backplate of the clearance ring section of shearer drums. In practice, most of the drums were seen to be withdrawn from the face due to the abovementioned problems, while vane picks and their holders were intact due to the improper lacing design of the clearance ring picks. However, few underground investigations and their results on the effect of lacing arrangement of clearance picks on the service life of shearer drums have been published. Nevertheless, the pick consumption characteristics of shearer drums were not investigated in detail, since these are fewer pick consumptions with shearers when compared to roadheaders. This paper is concerned with the comprehensive in situ trials on the effect of lacing of clearance ring picks on the lifespan of shearer drums, and the pick consumption characteristics of longwall shearers at Cayirhan Coal Mine in Turkey. The lifespan of shearer drums employed with shearers in this mine increased 70 per cent, while the consumption rate of clearance ring picks decreased three fold through using an alternative lacing for clearance picks, indicating the significance of utilizing proper design techniques for clearance ring picks for the service life of shearer drums. Statistical analyses carried out, using the raw pick consumption data, implied that the clearance ring picks experienced much higher loads than vane picks, revealing that special attention must be paid to designing clearance ring picks. An average maximum consumption value of 41 was determined for clearance ring picks, with corner-cutting picks having the most replacements, while it was 35 for vane picks, on three-day based pick replacements.

In vitro studies on the colonization of bovine colonic mucosa by Shiga-toxigenic Escherichia coli (STEC)

This study investigated host-related factors that influence intestinal colonization by Shiga-toxigenic E. coli (STEC). A quantitative colonization assay was developed to comparatively measure attachment of STEC to bovine colonic tissues maintained in vitro. No differences were determined in colonization susceptibility between tissues derived from weaning calves and adult cattle, or for tissues from cattle fed grain and forage-based rations. Substrate conditions designed to represent various intra-enteric environments were tested for their effect on STEC/mucosal interaction. Under conditions corresponding to a well-fed ruminant (high volatile fatty acid and lactate concentrations, low pH), significantly less STEC colonized the mucosal surface of colonic biopsies. These results may help explain why fasted. poorly or intermittently fed cattle and pre-ruminant calves excrete STEC to a greater degree. Studies on the ecology of STEC within the ruminant gut help identify mechanisms to reduce their threat to public health.

Interpretation of the temperature dependence of rate constants in biosensor studies

A comparison is made between Arrhenius and transition-state analyses of the temperature dependence of rate constants reported in four published biosensor studies. Although the Eyring transition-state theory seemingly affords a more definitive solution to the problem of characterizing the activation energetics, the analysis is equivocal because of inherent assumptions about reaction mechanism and the magnitude of the transmission coefficient. In view of those uncertainties it is suggested that a preferable course of action entails reversion to the empirical Arrhenius analysis with regard to the energy of activation and a preexponential factor. The former is essentially equivalent to the enthalpy of activation, whereas the magnitude of the latter indicates directly the extent of disparity between the frequency of product formation and the universal frequency factor (temperature multiplied by the ratio of the Boltzmann and Planck constants) and hence the likelihood of a more complicated kinetic mechanism than that encompassed by the Eyring transition-state theory. (C) 2004 Elsevier Inc. All rights reserved.