Dual in-aquifer and near surface processes drive arsenic mobilization in Cambodian groundwaters

Millions of people globally, and particularly in South and Southeast Asia, face chronic exposure to arsenic from reducing groundwaters in which. Arsenic release to is widely attributed largely to reductive dissolution of arsenic-bearing iron minerals, driven by metal reducing bacteria using bioavailable organic matter as an electron donor. However, the nature of the organic matter implicated in arsenic mobilization, and the location within the subsurface where these processes occur, remains debated. In a high resolution study of a largely pristine, shallow aquifer in Kandal Province, Cambodia, we have used a complementary suite of geochemical tracers (including ¹⁴C, ³H, ³He, ⁴He, Ne, δ¹⁸O, δD, CFCs and SF₆) to study the evolution in arsenic-prone shallow reducing groundwaters along dominant flow paths. The observation of widespread apparent ³H-³He ages of <55years fundamentally challenges some previous models which concluded that groundwater residence times were on the order of hundreds of years. Surface-derived organic matter is transported to depths of >30m, and the relationships between age-related tracers and arsenic suggest that this surface-derived organic matter is likely to contribute to in-aquifer arsenic mobilization. A strong relationship between ³H-³He age and depth suggests the dominance of a vertical hydrological control with an overall vertical flow velocity of ~0.4±0.1m·yr^-1 across the field area. A calculated overall groundwater arsenic accumulation rate of ~0.08±0.03μM·yr^-1 is broadly comparable to previous estimates from other researchers for similar reducing aquifers in Bangladesh. Although apparent arsenic groundwater accumulation rates varied significantly with site (e.g. between sand versus clay dominated sequences), rates are generally highest near the surface, perhaps reflecting the proximity to the redox cline and/or depth-dependent characteristics of the OM pool, and confounded by localized processes such as continued in-aquifer mobilization, sorption/desorption, and methanogenesis.

Effects of personal air pollution exposure on asthma symptoms, lung function and airway inflammation

BACKGROUND

There is evidence that air pollution increases the risk of asthma hospitalizations and healthcare utilization, but the effects on day-to-day asthma control are not fully understood.

OBJECTIVE

We undertook a prospective single-centre panel study to test the hypothesis that personal air pollution exposure is associated with asthma symptoms, lung function and airway inflammation.

METHODS

Thirty-two patients with a clinical diagnosis of asthma were provided with a personal air pollution monitor (Cairclip NO₂ /O₃ ) which was kept on or around their person throughout the 12-week follow-up period. Ambient levels of NO₂ and particulate matter were modelled based upon satellite imaging data. Directly measured ozone, NO₂ and particulate matter levels were obtained from a monitoring station in central Leicester. Participants made daily electronic records of asthma symptoms, peak expiratory flow and exhaled nitric oxide. Spirometry and asthma symptom questionnaires were completed at fortnightly study visits. Data were analysed using linear mixed effects models and cross-correlation.

RESULTS

Cairclip exposure data were of good quality with clear evidence of diurnal variability and a missing data rate of approximately 20%. We were unable to detect consistent relationships between personal air pollution exposure and clinical outcomes in the group as a whole. In an exploratory subgroup analysis, total oxidant exposure was associated with increased daytime symptoms in women but not men.

CONCLUSIONS AND CLINICAL RELEVANCE

We did not find compelling evidence that air pollution exposure impacts on day-to-day clinical control in an unselected asthma population, but further studies are required in larger populations with higher exposure levels. Women may be more susceptible than men to the effects of air pollution, an observation which requires confirmation in future studies.

Pathology of Runting in Farmed Saltwater Crocodiles (Crocodylus porosus) in Australia

Extremely poor growth of some individuals within a birth cohort (runting) is a significant problem in crocodile farming. We conducted a pathological investigation to determine if infectious disease is associated with runting in farmed saltwater crocodiles ( Crocodylus porosus) and to look for evidence of other etiologies. In each of 2005 and 2007, 10 normal and 10 runt crocodiles, with an average age of 5.5 months and reared under identical conditions, were sampled. Laboratory testing included postmortem; histological examination of a wide variety of tissues (with quantitation of features that were noted subjectively to be different between groups); hematology; serum biochemistry (total protein, albumin, globulins, total calcium, phosphorus, and iron); bacterial culture of liver and spleen (2005 only); viral culture of liver, thymus, tonsil, and spleen using primary crocodile cell lines (2007 only); and serum corticosterone (2007 only). The only evidence of infectious disease was mild cutaneous poxvirus infection in 45% of normal and 40% of runt crocodiles and rare intestinal coccidia in 5% of normal and 15% of runt crocodiles. Bacterial and viral culture did not reveal significant differences between the 2 groups. However, runt crocodiles exhibited significant ( P < .05) increases in adrenocortical cell cytoplasmic vacuolation and serum corticosterone, decreased production of bone (osteoporosis), and reduced lymphoid populations in the spleen, tonsil, and thymus. Runts also exhibited moderate anemia, hypoalbuminemia, and mild hypophosphatemia. Taken together, these findings suggest an association between runting and a chronic stress response (hyperactivity of the hypothalamic-pituitary-adrenal axis).

Children's palliative care: a global concern

Children's palliative care (CPC) is a specialty in itself, albeit closely related to adult palliative care (World Health Organization (WHO), 2002). However, although there are many children who require palliative care, in much of the world CPC has a poor profile and is inaccessible to those who need it (Downing et al, 2010; Knapp et al, 2011). The provision of high-quality palliative care for children is a global concern, with 27% of the world population being under the age of 15, rising to as many as 49% in countries such as Uganda (WHO, 2010). It has been estimated that as many as 7 million of these children around the world will need palliative care each year (Rushton et al, 2002), although the true figure is likely to be higher. The public health approach to palliative care is key to the development of CPC services, as is the development of models that integrate services into existing health structures.

Issues associated with the use of modified texture foods

Use of modified texture foods (MTF) is common in the geriatric population. There is a potential for increased prevalence of use of MTF due in part to longer survival of persons with dementia, those who have suffered from a stroke, as well as other degenerative diseases that affect chewing and swallowing. Unfortunately, little clinical, nutritional and sensory research has been conducted on MTF to inform practice. This review highlights issues identified in the literature to date that influence nutritional and sensory quality and acceptability of these foods. Use of MTF is highly associated with undernutrition, however causality is difficult to demonstrate due to confounding factors such as the requirement for feeding assistance. Knowledge gaps and considerations that need to be taken into account when conducting research are identified.

Cloning and pharmacological characterization of the dog P2X7 receptor

BACKGROUND AND PURPOSE

Human and rodent P2X7 receptors exhibit differences in their sensitivity to antagonists. In this study we have cloned and characterized the dog P2X7 receptor to determine if its antagonist sensitivity more closely resembles the human or rodent orthologues.

EXPERIMENTAL APPROACH

A cDNA encoding the dog P2X7 receptor was isolated from a dog heart cDNA library, expressed in U-2 OS cells using the BacMam viral expression system and characterized in electrophysiological, ethidium accumulation and radioligand binding studies. Native P2X7 receptors were examined by measuring ATP-stimulated interleukin-1beta release in dog and human whole blood.

KEY RESULTS

The dog P2X7 receptor was 595 amino acids long and exhibited high homology (>70%) to the human and rodent orthologues although it contained an additional threonine at position 284 and an amino acid deletion at position 538. ATP possessed low millimolar potency at dog P2X7 receptors. 2'-&3'-O-(4benzoylbenzoyl) ATP had slightly higher potency but was a partial agonist. Dog P2X7 receptors possessed relatively high affinity for a number of selective antagonists of the human P2X7 receptor although there were some differences in potency between the species. Compound affinities in human and dog blood exhibited a similar rank order of potency as observed in studies on the recombinant receptor although absolute potency was considerably lower.

CONCLUSIONS AND IMPLICATIONS

Dog recombinant and native P2X7 receptors display a number of pharmacological similarities to the human P2X7 receptor. Thus, dog may be a suitable species for assessing target-related toxicity of antagonists intended for evaluation in the clinic.

Degradation of extracellular matrix components by defined proteinases from the greenbottle larva Lucilia sericata used for the clinical debridement of non-healing wounds

BACKGROUND

Larvae of the greenbottle fly Lucilia sericata are used routinely for the clinical treatment of difficult necrotic and infected wounds. Degradation by proteinases contained in larval excretory/secretory (ES) products is thought to contribute to wound debridement by removal of dead tissue. However, proteinase activity may also affect host tissue remodelling processes.

OBJECTIVES

To identify proteolytic enzymes derived from L. sericata ES products with activities against fibrin and extracellular matrix (ECM) components.

METHODS

Larval proteinase activities were assayed in vitro using class-specific substrates and inhibitors. Their action against fibrin and ECM components was examined using sodium dodecyl sulphate-polyacrylamide gel electrophoresis.

RESULTS

Three classes of proteolytic enzyme were detected in the secretions using fluorescein isothiocyanate-labelled casein as a model substrate. The predominant activity belonged to serine proteinases (pH optima 8-9) of two different subclasses (trypsin-like and chymotrypsin-like), with a weaker aspartyl proteinase (pH 5) and a metalloproteinase (pH 9) with exopeptidase characteristics also present. Using skin-relevant ECM components as substrates L. sericata ES products solubilized fibrin clots and degraded fibronectin, laminin and acid-solubilized collagen types I and III. Hydrolysis of ECM macromolecules was inhibited by preincubating ES products with phenylmethylsulphonyl fluoride but not 4-amidinophenylmethylsulphonyl fluoride, indicating that degradation was due to the 'chymotrypsin-like' serine proteinase.

CONCLUSIONS

These data suggest that a combination of L. sericata ES proteinases involving chymotrypsin-like and trypsin-like activities could potentially influence wound healing events when maggots are introduced into necrotic and infected wounds, with the chymotrypsin-like activity involved in the remodelling of ECM components.

Factors associated with long-term institutionalization of older people with dementia: data from the Canadian Study of Health and Aging

BACKGROUND

In Canada, half the people with dementia live in institutions. Factors associated with institutionalization should be identified with the goal of implementing strategies not only to permit those with dementia to stay in their homes as long as is feasible but also to ensure that steps are taken for timely institutionalization when appropriate.

METHODS

Informal caregivers of 326 individuals with dementia living in the community were identified and interviewed as part of the Canadian Study of Health and Aging (CSHA). These subjects were contacted again 2.5 and 5 years after the baseline interview to collect information on the status of their care recipients. Survival analyses using clinical data for the individuals with dementia and data from the interviews with their informal caregivers were carried out using Cox proportional hazard modeling to estimate the hazard ratio (HR).

RESULTS

Over the 5-year period, 166 individuals with dementia (50.9%) were institutionalized and the median time to admission was 41 months. From the multivariate analysis, the factors significantly associated with institutionalization were: type of dementia (Alzheimer's disease: HR = 1.83), severity of disability (mild: 1.51; moderate: 2.34; total impairment: 4.02), caregiver's age over 60 (1.83), caregiver not a spouse or child (1.55), and severe caregiver burden (1.71). Caregiver's burden was associated with the care-receiver's behavioral disturbance (partial r =.55) and the caregiver's depressive mood (r =.55).

CONCLUSIONS

Screening caregivers for burden and depression and designing interventions to decrease the consequences of behavioral disturbance on caregivers would be relevant avenues to explore to decrease institutionalization of people with dementia.

Reproductive changes in fluctuating house mouse populations in southeastern Australia

House mice (Mus domesticus) in the Victorian mallee region of southeastern Australia show irregular outbreaks. Changes in reproductive output that could potentially drive changes in mouse numbers were assessed from 1982 to 2000. Litter size in females is positively correlated with body size. When standardized to an average size female, litter size changes seasonally from highest in spring to lowest in autumn and winter. Litter size is depressed throughout breeding seasons that begin when the abundance of mice is high, but is similar in breeding seasons over which the abundance of mice increases rapidly or remains low. Breeding begins early and is extended on average by about five weeks during seasons when mouse abundance increases rapidly. The size at which females begin to reproduce is larger during breeding seasons that begin when mouse abundance is high. An extended breeding season that begins early in spring is necessary for the generation of a house mouse plague, but it is not in itself sufficient. Reproductive changes in outbreaks of house mice in Australia are similar but not identical to reproductive changes that accompany rodent population increases in the Northern Hemisphere. We conclude that food quality, particularly protein, is a probable mechanism driving these reproductive changes, but experimental evidence for field populations is conflicting.

Short-term adverse health effects in a community exposed to a large polyvinylchloride plastics fire

The purpose of this study was the documentation of the short-term morbidity and mortality experiences of an urban community exposed to the airborne byproducts of a large polyvinylchloride plastics fire. The authors administered a survey to representatives of each household who had lived in an area evacuated during the fire. A time-series analysis was performed on emergency room visits and admissions for all hospitals in the city. Chloracne surveillance was instituted. Sixty-two percent of the individuals surveyed from the evacuation area reported no health concerns or symptoms related to the fire. Thirty-eight percent of the residents reported symptoms, and less than 2% of those surveyed reported that they sought medical attention for their health concerns. There was no evidence of increased hospital admissions or emergency room use during and immediately following the fire. No cases of chloracne were reported, and no deaths or serious injuries occurred during the fire. Polyvinylchloride plastics recycling plants pose potential health hazards to civilian populations. Public health authorities should be prepared to assess population health status rapidly and to disseminate relevant health information in a timely way during a crisis.

Using the U.S. Behavior Risk Factor Surveillance System's health related quality of life survey tool in a Canadian city

As responsibility for health funding shifts from central to local governments, providers find themselves in decision-making roles or asked to give guidance in allocation of resources. To develop a picture of a population's health, data are needed about the effects that illness and disability have on a person's ability to function and thus on quality of life. This study assessed the validity in a Canadian city, of a Health-related Quality of Life (HRQoL) instrument developed by the US Centers for Disease Control and used in the US Behavioral Risk Factor Surveillance System. The HRQoL was administered to a random sample of 1,042 adults. The patterns of association among the HRQoL questions, and the direction of the relationships among independent variables and HRQoL were consistent with those hypothesized. The accumulating evidence for validity of the HRQoL support its use in monitoring the performance of local health initiatives in Canada.

Relationships between drinking motives and drinking restraint

Relationships between drinking motives (self-perceived reasons for drinking alcohol) and drinking restraint (preoccupation with controlling alcohol intake) were examined in a nonclinical young adult sample. Ninety-seven undergraduate university drinkers completed the Temptation and Restraint Inventory (Collins & Lapp, 1992), the Drinking Motives Questionnaire (Cooper, Russell, Skinner, & Windle, 1992), and measures of demographics (age and gender) and social desirability. Results indicated that after accounting for the influences of demographic and social desirability information, Coping Motives and Enhancement Motives scores from the Drinking Motives Questionnaire were significant predictors of Cognitive and Emotional Preoccupation scores on the Temptation and Restraint Inventory, and Coping Motives scores were a significant predictor of Cognitive and Behavioral Control scores on the Temptation and Restraint Inventory. Social Motives scores on the Drinking Motives Questionnaire did not significantly predict either Cognitive and Emotional Preoccupation or Cognitive and Behavioral Control scores. Further analyses suggested that actual behavioral attempts at alcohol restriction on the Temptation and Restraint Inventory were predicted by Enhancement Motives scores, whereas cognitive concerns about drinking were predicted by Coping Motives scores. Results are discussed in terms of implications for risk for excessive and problem drinking in enhancement and coping-motivated young adult drinkers.

Patterns of self-reported health care use in injured and uninjured older adults

METHOD

Using cross-sectional data obtained from the 1994 National Population Health Survey, we have compared self-reported health-care use between injured and non-injured older adults.

RESULTS

Over 12 months, 9% of non-institutionalized people over 65 reported an injury. The commonest injuries were sprains or strains and fractures and half of these were caused by a fall. Older people sustaining injuries are more likely to spend a night in hospital and receive physiotherapy.

Enzymatically active papain preferentially induces an allergic response in mice

Human exposure to papain, a cysteine proteinase, is associated with hypersensitivity reactions. We demonstrate in mice that enzymatically active papain preferentially induces an IgG1 response and results in mast cell degranulation, both features typical of an allergic reaction. Inactive papain, blocked with E-64, appears to desensitize mice to subsequent challenge by active enzyme. These results suggest that the enzymatic activity of papain is critical in inducing an allergic response and that the use of inactive allergens may be a possible strategy for desensitizing allergic individuals.

Prospective care of elderly patients in family practice. Is screening effective?

OBJECTIVE

To evaluate cost and benefits of screening for and treating health and lifestyle risks among community-dwelling elderly.

DESIGN

Randomized controlled trial.

SETTING

Primary care.

PARTICIPANTS

An opportunistic and prompted sample of 619 rostered elderly patients presenting for treatment who screened positive.

INTERVENTIONS

One third (209) of experimental subjects had screening questionnaires placed in their charts with concerns highlighted for referrals. Two control groups received usual care.

MAIN OUTCOME MEASURES

Yearly assessments of health service use and multidimensional functional capacity.

RESULTS

Overall, screening and treatment of functionally active, elderly, middle-class people had no significant beneficial effect. Almost half of the experimental sample was ineligible because of treatment noncompliance. Generally ineligible subjects were older and more severely impaired. Subjects 75 years and older with risk factors showed improvement in daily living activities, and those living alone were found to have improved mental health and social functions (11% and 22%, respectively).

CONCLUSIONS

Screening and treatment was ineffective in improving total functional capacity of all seniors 65 years and older. Elderly people 75 years and older, however, who were living alone or lonely did benefit from screening and treatment showing an improvement in daily activities, mental health scores, and social functions. This finding has implications for selective preventive health care spending for the elderly. A 2-year follow-up period could be too brief to detect long-term effects of early intervention with younger, middle-class seniors, especially those who are already functionally active.

A review of risk factors for child pedestrian injuries: are they modifiable?

PURPOSE

To identify modifiable risk factors for child pedestrian injuries.

DATA SOURCES

(1) MEDLINE search from 1985 to 1995; search term used was traffic accidents; (2) review of reference lists from retrieved articles and books; (3) review of reference lists from three systematic reviews on childhood injuries and (4) consultation with 'key informants'.

STUDY SELECTION

All studies that examined the risk factors for child pedestrian injuries were targeted for retrieval. Seventy potentially relevant articles were identified using article titles, and, when available, abstracts. Of the 70 retrieved articles, 44 were later assessed as being relevant.

QUALITY ASSESSMENT

Articles were classified on the basis of study design as being either descriptive (hypothesis generating) (26) or analytical (hypothesis testing) (18) studies. Consensus was used for difficult to classify articles.

DATA EXTRACTION

Variables judged to be risk factors for child pedestrian injuries were extracted by one author.

DATA SYNTHESIS

A qualitative summary of the information extracted from relevant articles is presented in tabular form.

RESULTS

Risk factors for child pedestrian injuries were classified as: (1) child, (2) social and cultural, (3) physical environment, and (4) driver. Risk factors within each classification are summarized and discussed.

Toxaphene, PCB, DDT, and Chlordane Analyses of Beluga whale blubber

Beluga whales bioaccumulate organochlorines from their environment. Blubber samples of Beluga Whales from Alaska's north coast contain organochlorines, including Toxaphene (polychlorinated camphenes) PCBs, DDTs and chlordane. Toxaphene was the organochlorine pesticide found in the highest concentration in all samples with the exception of the 6 year old male where PCBs were highest. The source of these organochlorines is likely global distillation from lower latitudes. Males had higher concentrations than females and the oldest male had higher concentration than the younger male. Females exhibit a decrease in concentrations with age. The fetus had about 10% higher concentrations for all organochlorines compared to the mother. Transplacental transfer of organochlorines and lactation lower the contaminant concentration in females. Older females have lower contaminate concentrations likely due to continual reproductive success. Consumption of older males will expose humans to higher levels of organochlorines.

The house dust mite allergen Der p1 catalytically inactivates alpha 1-antitrypsin by specific reactive centre loop cleavage: a mechanism that promotes airway inflammation and asthma

Der p1, a cysteine proteinase derived from the house dust mite (HDM) Dermatophagoides pteronyssinus, is a major component of the allergic immune response in HDM atopic individuals. Recent evidence suggests that cysteine proteinase activity is important in the disease process as it increases the permeability of the allergen in the respiratory tract and disrupts the regulation of IgE synthesis. Der p1 is found in high concentrations in the faecal pellets of mites which are aerosolised and inhaled via the respiratory tract. The serine proteinase inhibitor, alpha 1-antitrypsin, protects the lower respiratory tract against damage by proteinases released in the lung during inflammation. Der p1 catalytically inactivates alpha 1-antitrypsin by a thiol-dependent mechanism involving specific cleavage of the reactive centre loop and we propose that this mechanism may be important in the pathogenesis of asthma.

NIST SRM 1945, whale blubber, NIST SRM 1974a, organics in mussel tissue, and NIST SRM 1941a, organics in marine sediment as certified reference materials for polychlorinated dioxins and furans in marine ecosystems

Few natural matrix Standard Reference Materials are available for the validation of analytical methods measuring polychlorinated dioxins and furans (PCDDs and PCDFs) in marine ecosystems. The concentrations of PCDDs and PCDFs in NIST SRM 1945, SRM 1974a, and SRM 1941a are of interest because the analysis of marine mammal, mussel tissues and sediments have become important tools in the determination of organochlorine contamination of the environment. Because these SRMs have been demonstrated to be homogenous for other organic contaminants, they would be expected to be reliable standards for validation of polychlorinated dioxins and furans in marine mammals, mussels and sediments as well.

Reversal of baseline relations and stimulus equivalence: II. Children

In a systematic replication of a study using college-student subjects (Pilgrim & Galizio, 1990), 5- to 7-year-old children learned two conditional discriminations (i.e., A1B1, A2B2, A1C1, and A2C2) in a two-choice arbitrary match-to-sample task and showed the emergence of two three-member equivalence classes (A1B1C1 and A2B2C2). Baseline conditional discrimination performance were quickly controlled by reversals of the AC reinforcement contingencies (i.e., choosing Comparison Stimulus C2 was reinforced given Sample A1, and choosing C1 was reinforced given Sample A2) when the reversals were introduced in restricted baselines. On reflexivity, symmetry, and transitivity/equivalence probes following the reversal, there was some limited indication of equivalence-class reorganization (i.e., A1B1C2 and A2B2C1) in keeping with the concurrently performed baseline relations for 2 of 5 subjects, but the predominant pattern across probe trials was one of inconsistent conditional control. These findings suggest that, given similar challenges, equivalence-class performances may be more easily disrupted in young children than in adults.

Piloting short workshops on the critical appraisal of reviews

This paper describes a pilot programme of short workshops on the critical appraisal of review articles. The twelve workshops, which ran in various parts of the United Kingdom during 1992 and 1993, lasted either one or two half-days, and consisted of a mixture of large-group sessions and critical appraisal in small groups of a systematic review. The 274 participants came from varied backgrounds, though chiefly in public health and purchasing. The workshops were well received and were oversubscribed. Participants reported that they found them useful and that they raised their awareness of the place of evidence about effectiveness in decision-making. The challenge now is to evaluate the impact of such workshops more rigorously.