Free radicals in alcoholic myopathy: Indices of damage and preventive studies

Chronic alcoholic myopathy affects up to two-thirds of all alcohol misusers and is characterized by selective atrophy of Type If (glycolytic, fast-twitch, anaerobic) fibers. In contrast, the Type I fibers (oxidative, slow-twitch, aerobic) are relatively protected. Alcohol increases the concentration of cholesterol hydroperoxides and malondialdehyde-protein adducts, though protein-carbonyl concentration levels do not appear to be overtly increased and may actually decrease in some studies. In alcoholics, plasma concentrations of a-tocopherol may be reduced in myopathic patients. However, a-tocopherol supplementation has failed to prevent either the loss of skeletal muscle protein or the reductions in protein synthesis in alcohol-dosed animals. The evidence for increased oxidative stress in alcohol-exposed skeletal muscle is thus inconsistent. Further work into the role of ROS in alcoholic myopathy is clearly warranted. (C) 2002 Elsevier Science Inc.

PrrC from Rhodobacter sphaeroides, a homologue of eukaryotic Sco proteins, is a copper-binding protein and may have a thiol-disulfide oxidoreductase activity

PrrC from Rhodobacter sphaeroides provides the signal input to a two-component signal transduction system that senses changes in oxygen tension and regulates expression of genes involved in photosynthesis (Eraso, J.M. and Kaplan, S. (2000) Biochemistry, 39, 2052-2062; Oh, J.-I. and Kaplan, S. (2000) EMBO J. 19, 42374247). It is also a homologue of eukaryotic Sco proteins and each has a C-x-x-x-C-P sequence. In mitochondrial Sco proteins these cysteines appear to be essential for the biogenesis Of the Cu-A centre of respiratory cytochrome oxidase. Overexpression and purification of a water-soluble and monomeric form of PrrC has provided sufficient material for a chemical and spectroscopic study of the properties of the four cysteine residues of PrrC, and its ability to bind divalent cations, including copper. PrrC expressed in the cytoplasm of Escherichia coli binds Ni2+ tightly and the data are consistent with a mononuclear metal site. Following removal of Ni2+ and formation of renatured metal-free rPrrC (apo-PrrC), Cu2+ could be loaded into the reduced form of PrrC to generate a protein with a distinctive UV-visible spectrum, having absorbance with a lambda(max) of 360 nm. The copper:PrrC ratio is consistent with the presence of a mononuclear metal centre. The cysteines of metal-free PrrC oxidise in the presence of air to form two intramolecular disulfide bonds, with one pair being extremely reactive. The cysteine thiols with extreme O-2 sensitivity are involved in copper binding in reduced PrrC since the same copper-loaded protein could not be generated using oxidised PrrC. Thus, it appears that PrrC, and probably Sco proteins in general, could have both a thiol-disulfide oxidoreductase function and a copper-binding role. (C) 2002 Published by Elsevier Science B.V. on behalf of the Federation of European Biochemical Societies.

A review of animal models for the study of arsenic carcinogenesis

As inorganic arsenic is a proven human carcinogen, significant effort has been made in recent decades in an attempt to understand arsenic carcinogenesis using animal models, including rodents (rats and mice) and larger mammals such as beagles and monkeys. Transgenic animals were also used to test the carcinogenic effect of arsenicals, but until recently all models had failed to mimic satisfactorily the actual mechanism of arsenic carcinogenicity. However, within the past decade successful animal models have been developed using the most common strains of mice or rats. Thus dimethylarsinic acid (DMA), an organic arsenic compound which is the major metabolite of inorganic arsenicals in mammals, has been proven to be tumorigenic in such animals. Reports of successful cancer induction in animals by inorganic arsenic (arsenite and arsenate) have been rare, and most carcinogenetic studies have used organic arsenicals such as DMA combined with other tumor initiators. Although such experiments used high concentrations. of arsenicals for the promotion of tumors, animal models using doses of arsenicals species closed to the exposure level of humans in endemic areas are obviously the most significant. Almost all researchers have used drinking water or food as the pathway for the development of animal model test systems in order to mimic chronic arsenic poisoning in humans; such pathways seem more likely to achieve desirable results. (C) 2002 Elsevier Science Ireland Ltd. All rights reserved.

Cadmium levels in the lung, liver, kidney cortex, and urine samples from Australians without occupational exposure to metals

The authors undertook this study to assess levels of cadmium exposure in the general population. Samples of lung, liver, and kidney were obtained from 61 cadavers (43 males, 18 females; 2-89 yr of age, mean age = 38.5 yr) who died from accidental causes and who were subject to postmortem examinations at the John Tonge Centre for Forensic Sciences, Queensland Health Scientific Services, Brisbane, Australia, in 1997 and 1998. Samples of bladder urine were also obtained from 22 cadavers. Tissue and urine samples were analyzed for cadmium, zinc, and copper with inductively coupled plasm (ICP) mass spectrometry. The overall mean values for cadmium in the lung, liver, and kidney cortex samples were 0.13, 0.95, and 15.45 mug/gm wet tissue weight. The average renal cadmium level in subjects with high lung-cadmium levels (n = 13) was 6 mug/gm wet tissue weight higher than that of similarly aged subjects who had medium lung-cadmium levels (n = 30). In females, the average level of cadmium in the liver was 74% greater than in males, and the average liver cadmium in females with high lung-cadmium levels was 100% higher than in males in the same age range who had the same high lung-cadmium levels. Renal cadmium accumulation tended to be greater in females than in males who were in the same age range and who had similar lung-cadmium levels, a result that suggested that there was a higher absorption rate of cadmium in females. The mean value for a urinary cadmium excretion of 2.30 mug/gm creatinine was found in a subset of samples that had a mean age of 39 yr and a renal cortex cadmium concentration of 18.6 mug/gm wet tissue weight. Urinary cadmium excretion rates were correlated more strongly with lung and kidney cadmium content than with age or liver cadmium levels. The results suggest that urinary cadmium excretion may be increased in smokers and could provide some estimate of body cadmium burdens in future Australian epidemiological studies.

Polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans in sediments from Hong Kong

Concentrations of 2,3,7,8-substituted polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) were determined in 14 sediment samples collected from four sites in the Mai Po Marshes Nature Reserve (within a RAMSAR Site) and from another six sites in Victoria Harbour and along the Hong Kong coastline. Elevated levels of PCDDs, and particularly OCDD, were detectable in all samples collected from the Mai Po Marshes and five of the six sites. In contrast to PCDDs, PCDFs were mainly found in sediment samples collected from industrial areas (Kwun Tong and To Kwa Wan) in Victoria Harbour. PCDD/F levels and congener profiles in the samples from the Mai Po Marshes Nature Reserve in particular show strong similarities to those reported in studies which have attributed similar elevated PCDD concentrations to nonanthropogenic PCDD sources. (C) 2002 Elsevier Science Ltd. All rights reserved.

Variation in coumarin 7-hydroxylase activity associated with genetic polymorphism of cytochrome P450 2A6 and the body status of iron stores in adult Thai males and females

The relationships between catalytic activity of cytochrome P450 2A6 (CYP2A6), polymorphism of CYP2A6 gene, gender and levels of body iron stores were analysed in a sample group of 202 apparently healthy Thais, aged 1947 years. Eleven individuals were found to have high activity of CYP2A6, judged by the relatively large amounts (11.2-14.6 mg) of 7-hydroyxcoumarin (7-OHC) excreted 3 h following administration of 15 mg of coumarin. Ten individuals, however, did not excrete any 7-OHC. Of these 10, four were found to have no CYP2A6 gene (whole gene deletion; CYP2A6*4 allele). The frequency of the CYP2A6 alleles; *1A, *1B and *4 in the whole sample group was 52, 40 and 8% while the frequency of the CYP2A6 gene types; *1A/* 1A, *1A/* 1B, *1B/* 1B, *1A/* 4, *1BI* 4, *4/* 4 was 29, 41, 16, 7, 5 and 2%. Subjects having CYP2A6* 1A/* 1B gene-type group were found to have higher rates of coumarin 7-hydroxylation compared with those of the CYP2A6* 1B/* 1B and CYP2A6* 1A/* 4 gene types. The inter-individual variability in CYP2A6 catalytic activity was therefore attributed in part to the CYP2A6 genetic polymorphism. Variation in CYP2A6 activity in this sample group was not associated with gender but, interestingly, it did show an inverse association with plasma ferritin; an indicator of body iron stores. Higher rates of coumarin 7-hydroxylation were found in individuals with low body iron stores (plasma ferritin < 20 μg/l) compared with subjects having normal body iron store status. Subjects (n = 16) with iron overload (plasma ferritin > 300 mug/l) also tended to have elevated rates of coumarin 7-hydroxylation. These results suggest an increased CYP2A6 expression in subjects who have excessive body iron stores. Further investigations into the underlying factors that may lead to increased expression of CYP2A6 in association with abnormal body iron stores are currently in progress in our laboratory. Pharmacogenetics 12:241-249 (C) 2002 Lippincott Williams Wilkins.

Cloud-point extraction and preconcentration of cyanobacterial toxins (microcystins) from natural waters using a cationic surfactant

A new cloud-point extraction and preconcentration method, using a cationic, surfactant, Aliquat-336 (tricaprylyl-methy;ammonium chloride), his-been developed for the determination of cyanobacterial toxins, microcystins, in natural waters. Sodium sulfate was used to induce phase separation at 25 degreesC. The phase behavior of Aliquat-336 with respect to concentration of Na2SO4 was studied. The cloud-point system revealed a very high phase volume ratio compared to other established systems of nonionic, anionic, and cationic surfactants: At pH 6-7, it showed an outstanding selectivity in ahalyte extraction for anionic species. Only MC-LR and MC-YR, which are known to be predominantly anionic, were extracted (with averaged recoveries of 113.9 +/- 9% and 87.1 +/- 7%, respectively). MC-RR, which is likely to be amphoteric at the above pH range, was. not cle tectable in.the extract. Coupled to HPLC/UV separation and detection, the cloud-point extraction method (with 2.5 mM Aliquat-336 and 75 mM Na2SO4 at 25 degreesC) offered detection limits of 150 +/- 7 and 470 +/- 72 pg/mL for MC-LR and MC-YR, respectively, in 25 mL of deionized water. Repeatability of the method was 7.6% for MC-LR and 7.3% for MC-YR: The cloud-point extraction process can be. completed within 10-15 min with no cleanup steps required. Applicability of the new method to the determination of microcystins in real samples was demonstrated using natural surface waters, collected from a local river and a local duck pond spiked with realistic. concentrations of microcystins. Effects of salinity and organic matter (TOC) content in the water sample on the extraction efficiency were also studied.

Who does not gain weight? Prevalence and predictors of weight maintenance in young women

OBJECTIVE: To investigate the prevalence and predictors of weight maintenance over time in a large sample of young Australian women. DESIGN: This population study examined baseline and 4y follow-up data from the cohort of young women participating in the Australian Longitudinal Study on Women's Health. SUBJECTS: A total of 8726 young women aged 18 - 23y at baseline. MEASURES: Height, weight and body mass index (BMI); physical activity; time spent sitting; selected eating behaviours (eg dieting, disordered eating, takeaway food consumption); cigarette smoking, alcohol consumption; parity; and socio-demographic characteristics. RESULTS: Only 44% of the women reported their BMI at follow-up to be within 5% of their baseline BMI (maintainers); 41% had gained weight and 15% had lost weight. Weight maintainers were more likely to be in managerial or professional occupations; to have never married; to be currently studying; and not to be mothers. Controlling for sociodemographic factors, weight maintainers were more likely to be in a healthy weight range at baseline, and to report that they spent less time sitting, and consumed less takeaway food, than women who gained weight. CONCLUSIONS: Fewer than half the young women in this community sample maintained their weight over this 4y period in their early twenties. Findings of widespread weight gain, particularly among those already overweight, suggest that early adulthood, which is a time of significant life changes for many women, may be an important time for implementing strategies to promote maintenance of healthy weight. Strategies which encourage decreased sitting time and less takeaway food consumption may be effective for encouraging weight maintenance at this life stage.

Investigations into the PCDD contamination of topsoil, river sediments and kaolinite clay in Queensland, Australia

Recent findings of elevated PCDDs from an unknown source in the coastal marine environment of Queensland, Australia has instigated further investigations into the distribution of, and environments associated with the PCDD contamination. This study presents data for OCDD concentrations in the coastal, mountainous and inland environment of Queensland. Additionally, full 2,3,7,8-substituted polychlorinated dibenzo-p-dioxins and dibenzofuran (PCDD/F) profiles from different land-use types and environments in the coastal region were analysed. Distinct east-west gradients were detected in topsoil collected from various bushland regions with elevated OCDD concentrations confined to the coastal region. However, PCDD/F results from topsoil and river sediments collected in the Queensland coastal region suggest that elevated OCDD concentrations cannot be attributed to any of the environments, land-use or industry types investigated. PCDD/F congener profiles from select samples were remarkably similar to those previously described in marine sediments collected along the entire Queensland coastline. In addition, kaolinite clay samples from Queensland exhibited elevated OCDD concentrations, and PCDD/F profiles in these samples were similar to those detected in kaolinite clays elsewhere. Natural formation processes have been hypothesised as the source of elevated PCDDs in Queensland and other locations, where similar PCDD/F profiles and the general lack of anthropogenic sources are evident. This study presents additional data supporting this hypothesis and provides further information that may assist in the identification of the processes involved in the natural formation of PCDDs. (C) 2002 Elsevier Science Ltd. All rights reserved.

The absorption and excretion of fluoride and arsenic in humans

The absorption and excretion of fluoride and arsenic were measured in a group of healthy volunteers given drinking water with naturally high concentration of fluoride (F 2.3 mg/l), or high concentration of arsenic (As 0.15 mg/l), or high concentrations of both fluoride and arsenic (F 2.25 mg/l, As 0.23 mg/l and F 4.05 mg/l, As 0.58 mg/l), respectively. The results indicated that, for arsenic, the absorption rate, the proportion of urinary excretion and the biological-half-life did not show statistically significant differences between drinking water containing high arsenic alone and drinking water containing different levels of high arsenic and fluoride. Excretion and retention of arsenic were positively correlated to the total arsenic intake. Similar results were observed for fluoride. This suggests that there are different metabolic processes for arsenic and fluoride in respect to absorption and excretion; and no joint action can be attributed by these two elements. (C) 2002 Elsevier Science Ireland Ltd. All rights reserved.

Structural ordering of coal char during heat treatment and its impact on reactivity

The effect of heat treatment on the structure of an Australian semi-anthracite char was studied in detail in the 850-1150degreesC temperature range using XRD, HRTEM, and electrical resistivity techniques. It was found that the carbon crystallite size in the char does not change significantly during heat treatment in the temperature range studied, for both the raw coal and its ash-free derivative obtained by acid treatment. However, the fraction of the organized carbon in the raw coal chars, determined by XRD, increased with increase of heat treatment time and temperature, while that for the ash-free coal chars remained almost unchanged. This suggests the occurrence of catalytic ordering during heat treatment, supported by the observation that the electrical resistivity of the raw coal chars decreased with heat treatment, while that of the ash-free coal chars did not vary significantly. Further confirmatory evidence was provided by high resolution transmission electron micrographs depicting well-organized carbon layers surrounding iron particles. It is also found that the fraction of organized carbon does not reach unity, but attains an apparent equilibrium value that increases with increase in temperature, providing an apparent heat of ordering of 71.7 kJ mol(-1) in the temperature range studied. Good temperature-independent correlation was found between the electrical resistivity and the organized carbon fraction, indicating that electrical resistivity is indeed structure sensitive. Good correlation was also found between the electrical resistivity and the reactivity of coal char. All these results strongly suggest that the thermal deactivation is the result of a crystallite-perfecting process, which is effectively catalyzed by the inorganic matter in the coal char. Based on kinetic interpretation of the data it is concluded that the process is diffusion controlled, most likely involving transport of iron in the inter-crystallite nanospaces in the temperature range studied. The activation energy of this transport process is found to be very low, at about 11.8 kJ mol(-1), which is corroborated by model-free correlation of the temporal variation of organized carbon fraction as well as electrical resistivity data using the superposition method, and is suggestive of surface transport of iron. (C) 2002 Elsevier Science Ltd. All rights reserved.

A field study conducted at Kidston Gold Mine, to evaluate the impact of arsenic and zinc from mine tailing to grazing cattle

The grazing trial at Kidston Gold Mine, North Queensland, was aimed specifically to assess the uptake of metals from the tailing and the potential for unacceptable contamination of saleable meat. Further aims included estimating metal dose rates and identifying potential exposure pathways including plant uptake of heavy metals, mine tailings adhered to plants and direct ingestion of mine tailing. It was found that of the 11 metals analysed (As, Zn, Co, Cd, Cr, Sn, Pb, Sb, Hg, Se and Ni) in the animal's liver, muscle and blood during the 8-month trial period, only accumulation of arsenic and zinc occurred. A risk assessment including these two metals was conducted to determine the potential for chronic metal toxicity and long-term contamination, using the estimates of metal dose rate. It was concluded that no toxicity or long-term contamination in cattle was likely at this site. Management procedures were therefore not required at this site; however, the results highlight percent ground cover and standing dry matter (DM) as important factors in decreasing metal exposure from direct ingestion of tailings and dust adhered to plants. (C) 2002 Elsevier Science Ireland Ltd. All rights reserved.

Porphyrins as early biomarkers for arsenic exposure in animals and humans

We studied the effect of arsenic exposure on the haem biosynthetic pathway in the rat and humans. Significant increases in protoporphyrin IX, coproporphyrin III, coproporphyrin I were observed in the blood, liver and kidney, and in the urine of rats after a single dose of arsenic. The level of increase was dependent on the arsenic species present. Most of porphyrin concentrations in the tissues increased within 24 hr and urinary excretion elevated within 48 hr. In the human study, we collected urine samples from 113 people who live in Xing Ren of Guizhou Province, a coal-borne arsenicosis endemic area in southwest of PR China and from 30 people who live in Xing Yi (about 80 km southwest of Xing Ren) where arsenicosis is not prevalent. We analyzed the urinary porphyrins using HPLC. Results indicate that all urinary porphyrins were higher in the arsenic exposed group than those in the control group. Women, children and older age people spend much of their time indoors, they had greater increases of urinary arsenic and porphyrins. They were the higher risk groups among the study subjects. A positive correlation between the urinary arsenic levels and porphyrin concentrations demonstrated the effect of arsenic on haem biosynthesis. Significant alteration in the porphyrin excretion profiles of the younger age (