Showing papers by "University of Adelaide published in 2005"
TL;DR: Treatment of gestational diabetes reduces serious perinatal morbidity and may also improve the woman's health-related quality of life.
Abstract: Background We conducted a randomized clinical trial to determine whether treatment of women with gestational diabetes mellitus reduced the risk of perinatal complications. Methods We randomly assig...
2,732 citations
TL;DR: This review focuses on those experimental studies that have investigated the critical windows during which perturbations of the intrauterine environment have major effects, the nature of the epigenetic, structural, and functional adaptive responses which result in a permanent programming of cardiovascular and metabolic function, and the role of the interaction between the pre- and postnatal environment in determining final health outcomes.
Abstract: The "fetal" or "early" origins of adult disease hypothesis was originally put forward by David Barker and colleagues and stated that environmental factors, particularly nutrition, act in early life to program the risks for adverse health outcomes in adult life. This hypothesis has been supported by a worldwide series of epidemiological studies that have provided evidence for the association between the perturbation of the early nutritional environment and the major risk factors (hypertension, insulin resistance, and obesity) for cardiovascular disease, diabetes, and the metabolic syndrome in adult life. It is also clear from experimental studies that a range of molecular, cellular, metabolic, neuroendocrine, and physiological adaptations to changes in the early nutritional environment result in a permanent alteration of the developmental pattern of cellular proliferation and differentiation in key tissue and organ systems that result in pathological consequences in adult life. This review focuses on those experimental studies that have investigated the critical windows during which perturbations of the intrauterine environment have major effects, the nature of the epigenetic, structural, and functional adaptive responses which result in a permanent programming of cardiovascular and metabolic function, and the role of the interaction between the pre- and postnatal environment in determining final health outcomes.
1,814 citations
TL;DR: Three genetic variants of the gene encoding catecholamine-O-methyltransferase determine COMT activity in humans that inversely correlates with pain sensitivity and the risk of developing TMD.
Abstract: Pain sensitivity varies substantially among humans. A significant part of the human population develops chronic pain conditions that are characterized by heightened pain sensitivity. We identified three genetic variants (haplotypes) of the gene encoding catecholamine-O-methyltransferase (COMT) that we designated as low pain sensitivity (LPS), average pain sensitivity (APS) and high pain sensitivity (HPS). We show that these haplotypes encompass 96% of the human population, and five combinations of these haplotypes are strongly associated (P 5 0.0004) with variation in the sensitivity to experimental pain. The presence of even a single LPS haplotype diminishes, by as much as 2.3 times, the risk of developing myogenous temporomandibular joint disorder (TMD), a common musculoskeletal pain condition. The LPS haplotype produces much higher levels of COMT enzymatic activity when compared with the APS or HPS haplotypes. Inhibition of COMT in the rat results in a profound increase in pain sensitivity. Thus, COMT activity substantially influences pain sensitivity, and the three major haplotypes determine COMT activity in humans that inversely correlates with pain sensitivity and the risk of developing TMD.
1,209 citations
TL;DR: Halloysite clay minerals are ubiquitous in soils and weathered rocks where they occur in a variety of particle shapes and hydration states as discussed by the authors and diversity also characterizes their chemical composition, cation exchange capacity and potassium selectivity.
Abstract: Halloysite clay minerals are ubiquitous in soils and weathered rocks where they occur in a variety of particle shapes and hydration states. Diversity also characterizes their chemical composition, cation exchange capacity and potassium selectivity. This review summarizes the extensive but scattered literature on halloysite, from its natural occurrence, through its crystal structure, chemical and morphological diversity, to its reactivity toward organic compounds, ions and salts, involving the various methods of differentiating halloysite from kaolinite. No unique test seems to be ideal to distinguish these 1:1 clay minerals, especially in soils. The occurrence of 2:1 phyllosilicate contaminants appears, so far, to provide the best explanation for the high charge and potassium selectivity of halloysite. Yet, hydration properties of the mineral probably play a major role in ion sorption. Clear trends seem to relate particle morphology and structural Fe. However, future work is required to understand the possible mechanisms linking chemical, morphological, hydration and charge properties of halloysite.
1,156 citations
TL;DR: A framework for understanding how zero-inflated data sets originate and deciding how best to model them is proposed and the different kinds of zeros that occur in ecological data are defined and classified.
Abstract: A common feature of ecological data sets is their tendency to contain many zero values. Statistical inference based on such data are likely to be inefficient or wrong unless careful thought is given to how these zeros arose and how best to model them. In this paper, we propose a framework for understanding how zero-inflated data sets originate and deciding how best to model them. We define and classify the different kinds of zeros that occur in ecological data and describe how they arise: either from 'true zero' or 'false zero' observations. After reviewing recent developments in modelling zero-inflated data sets, we use practical examples to demonstrate how failing to account for the source of zero inflation can reduce our ability to detect relationships in ecological data and at worst lead to incorrect inference. The adoption of methods that explicitly model the sources of zero observations will sharpen insights and improve the robustness of ecological analyses.
870 citations
TL;DR: In this paper, the authors integrated Neoproterozoic palaeomagnetic solutions from the various blocks that made up eastern Gondwana, with the large amount of recent geological data available from the orogenic belts that formed as eastern gondwana amalgamated.
810 citations
TL;DR: In this article, the authors used a sample of actual consumers from an Australian state capital city Confirmatory factor analysis employing structural equations modelling was used to measure consumer-based brand equity.
Abstract: Purpose – The present research aims to improve the measurement of consumer‐based brand equity Current measurement of consumer‐based brand equity suffers from limitations, including: a lack of distinction between the dimensions brand awareness and brand associations, the use of non‐discriminant indicators in the measurement scales and of student samplesDesign/methodology/approach – Based on the recommendations of extant research, the scale constructed to measure consumer‐based brand equity in this study included brand personality measures Brand associations were measured using a different set of items Unlike many of the previous studies that had used student samples, the present study used a sample of actual consumers from an Australian state capital city Confirmatory factor analysis employing structural equations modelling was used to measure consumer‐based brand equity in two product categories and across six brandsFindings – Results support the hypothesised four‐dimension model of consumer‐based b
747 citations
TL;DR: In this paper, the authors investigate, analyse and critique contemporary research in social and environmental accounting, focusing on practice and policy and offer an empirical analysis of the profile of SEA publication.
Abstract: Purpose – To investigate, analyse and critique contemporary research in social and environmental accountingDesign/methodology/approach – An analysis and critique of the social and environmental accountability (SEA) research field since the late 1980s The study revisits two key prior seminal papers on the field, examines the remit for SEA researchers' focus on practice and policy and offers an empirical analysis of the profile of SEA publicationFindings – Theories are identified in two groups: augmentation and heartland theories These have been more deductively than inductively generated, evidencing limited attention to field‐based engagement An alternative to the elusive all‐embracing unitary SEA theory is presented Researchers' concerns with capture of the SEA field is critiqued and an alternative researcher engagement orientation is offered Environmental research dominates more recent SEA published output, the dominant methodological approach is literature‐based theorising, and national practices
723 citations
TL;DR: This article examined the relationship between resource abundance and several indicators of human welfare and found that, given an initial income level, resource-intensive countries tend to suffer lower levels of human development.
623 citations
TL;DR: An improved protocol that performs RNA linker ligation before the SDS-PAGE step is presented, and its application to the specific purification and amplification of RNA ligands of Nova in neurons is described.
611 citations
TL;DR: It is demonstrated that, in humans, not only impaired or abolished gene function but also increased MeCP2 dosage causes a distinct phenotype, which justifies quantitative screening of MECP2 in this group of patients.
Abstract: Loss-of-function mutations of the MECP2 gene at Xq28 are associated with Rett syndrome in females and with syndromic and nonsyndromic forms of mental retardation (MR) in males. By array comparative genomic hybridization (array-CGH), we identified a small duplication at Xq28 in a large family with a severe form of MR associated with progressive spasticity. Screening by real-time quantitation of 17 additional patients with MR who have similar phenotypes revealed three more duplications. The duplications in the four patients vary in size from 0.4 to 0.8 Mb and harbor several genes, which, for each duplication, include the MR-related L1CAM and MECP2 genes. The proximal breakpoints are located within a 250-kb region centromeric of L1CAM, whereas the distal breakpoints are located in a 300-kb interval telomeric of MECP2. The precise size and location of each duplication is different in the four patients. The duplications segregate with the disease in the families, and asymptomatic carrier females show complete skewing of X inactivation. Comparison of the clinical features in these patients and in a previously reported patient enables refinement of the genotype-phenotype correlation and strongly suggests that increased dosage of MECP2 results in the MR phenotype. Our findings demonstrate that, in humans, not only impaired or abolished gene function but also increased MeCP2 dosage causes a distinct phenotype. Moreover, duplication of the MECP2 region occurs frequently in male patients with a severe form of MR, which justifies quantitative screening of MECP2 in this group of patients.
TL;DR: This article addresses the following questions: what is TI, how important and widespread is it, how does it work and where should the authors focus their future research efforts?
TL;DR: The input determination methodology is applied to a real-world case study in order to determine suitable model inputs for forecasting salinity in the River Murray, South Australia, 14 days in advance.
TL;DR: A modified version of the Neighbourhood Environment Walkability Scale was used to compare residents' perceptions of the attributes of two neighbourhoods that differed on measures derived from Geographic Information System databases, finding that perceived neighbourhood environment characteristics had moderate to high test-retest reliabilities.
TL;DR: Understanding the role of plant-microbe-soil interactions in governing nutrient availability in the rhizosphere will enhance the economic and environmental sustainability of crop production.
Abstract: Crop nutrition is frequently inadequate as a result of the expansion of cropping into marginal lands, elevated crop yields placing increasing demands on soil nutrient reserves, and environmental and economic concerns about applying fertilizers. Plants exposed to nutrient deficiency activate a range of mechanisms that result in increased nutrient availability in the rhizosphere compared with the bulk soil. Plants may change their root morphology, increase the affinity of nutrient transporters in the plasma membrane and exude organic compounds (carboxylates, phenolics, carbohydrates, enzymes, etc.) and protons. Chemical changes in the rhizosphere result in altered abundance and composition of microbial communities. Nutrient-efficient genotypes are adapted to environments with low nutrient availability. Nutrient efficiency can be enhanced by targeted breeding through pyramiding efficiency mechanisms in a desirable genotype as well as by gene transfer and manipulation. Rhizosphere microorganisms influence nutrient availability; adding beneficial microorganisms may result in enhanced availability of nutrients to crops. Understanding the role of plant-microbe-soil interactions in governing nutrient availability in the rhizosphere will enhance the economic and environmental sustainability of crop production.
TL;DR: In this article, a study of first-year tertiary students investigated the relationship between EI and a number of life skills (academic achievement, life satisfaction, anxiety, problem-solving and coping).
TL;DR: T careful analysis of existing prokaryotic molybdate transport mechanisms, as well as a re-examination of know anion transport mechanisms present in plants, will help to resolve how this important trace element is accumulated.
TL;DR: The complex molecular interactions of the ligands and receptors of the IGF system underlie all the biological actions mentioned above and will be the focus of this review.
TL;DR: This review summarises the current understanding of the physiology of responses to seminal plasma in the female reproductive tract and considers the evolutionary significance of seminal Plasma in influencing female tissues to promote the success of pregnancy.
Abstract: In mammals, insemination results in the transmission of seminal factors that act, in the female reproductive tract, to promote sperm survival, to “condition” the female immune response to tolerate the conceptus and to organise molecular and cellular changes in the endometrium to facilitate embryo development and implantation. These events are initiated when signalling agents, including transforming growth factor-β and other cytokines and prostaglandins secreted by seminal vesicle and prostate glands, interact with epithelial cells in the cervix and uterus to activate cytokine synthesis and to induce cellular and molecular changes resembling a classical inflammatory cascade. The consequences are the recruitment and activation of macrophages, granulocytes and dendritic cells, which have immune-regulatory and tissue-remodelling roles that culminate in improved endometrial receptivity to the implanting embryo. Cytokines elicited by seminal activation have embryotrophic properties and also contribute directly to the optimal development of the early embryo. This review summarises our current understanding of the physiology of responses to seminal plasma in the female reproductive tract and considers the evolutionary significance of seminal plasma in influencing female tissues to promote the success of pregnancy.
Journal Article•
TL;DR: This paper examined the underlying epistemological beliefs of popular constructivist theories and their criticisms and concluded that confusions about Vygotsky's theory often arise from concepts taken literally and from the lack of appreciation of the general philosophical orientation underpinning his works.
Abstract: Criticisms have recently been voiced of constructivism, the leading metaphor of human learning since the 1970s. Inspired by inconsistencies in interpretations of constructivism in current literature, we examine the underlying epistemological beliefs of popular constructivist theories and their criticisms. We find that popular constructivist claims and criticisms, instead of being based on contrasting philosophical ideas, are similarly grounded on the dualist separatism of the human mind and the external world. We then present our interpretation of Vygotsky’s historical-dialectical-monist philosophy, through discussions of Vygotskyan concepts including social environment of learning, the role of language, and individual consciousness. The paper concludes that confusions about Vygotsky’s theory often arise from concepts taken literally and from the lack of appreciation of the general philosophical orientation underpinning his works. Constructivism, criticisms, Vygotsky’s philosophy, historical-dialectical-monism, paradigmatic philosophy
TL;DR: The 3/4 power scaling of RMRpp is part of a wider trend where, with the notable exception of cold-induced maximum MR, large herbivores are therefore less likely to be postabsorptive when MR is measured, and are likely to have a relatively high MR if not post absorptionptive.
Abstract: The importance of size as a determinant of metabolic rate (MR) was first suggested by Sarrus and Rameaux over 160 years ago. Max Rubner's finding of a proportionality between MR and body surface area in dogs (in 1883) was consistent with Sarrus and Rameaux's formulation and suggested a proportionality between MR and body mass (Mb) raised to the power of 2/3. However, interspecific analyses compiled during the first half of the 20th century concluded that mammalian basal MR (BMR, ml O2 h(-1)) was proportional to Mb3/4, a viewpoint that persisted for seven decades, even leading to its common application to non-mammalian groups. Beginning in 1997, the field was re-invigorated by three new theoretical explanations for 3/4-power BMR scaling. However, the debate over which theory accurately explains 3/4-power scaling may be premature, because some authors maintain that there is insufficient evidence to adopt an exponent of 3/4 over 2/3. If progress toward understanding the non-isometric scaling of BMR is ever to be made, it is first essential to know what the relationship actually is. We re-examine previous investigations of BMR scaling by standardising units and recalculating regression statistics. The proportion of large herbivores in a data set is positively correlated both with the scaling exponent (b, where BMR=aMb b) and the coefficient of variation (CV: the standard deviation of ln-ln residuals) of the relationship. Inclusion of large herbivores therefore both inflates b and increases variation around the calculated trendline. This is related to the long fast duration required to achieve the postabsorptive conditions required for determination of BMR, and because peak post-feeding resting MR (RMRpp) scales with an exponent of 0.75+/-0.03 (95% CI). Large herbivores are therefore less likely to be postabsorptive when MR is measured, and are likely to have a relatively high MR if not postabsorptive. The 3/4 power scaling of RMRpp is part of a wider trend where, with the notable exception of cold-induced maximum MR (b=0.65+/-0.05), b is positively correlated with the elevation of the relationship (higher MR values scale more steeply). Thus exercise-induced maximum MR (b=0.87+/-0.05) scales more steeply than RMRpp, field MR (b=0.73+/-0.04), thermoneutral resting MR (RMRt, b=0.712+/-0.013) and BMR. The implication of this observation is that contamination of BMR data with non-basal measurements is likely to increase the BMR scaling exponent even if the contamination is randomly distributed with respect to Mb. Artificially elevated scaling exponents can therefore be accounted for by the inclusion of measurements that fail to satisfy the requirements for basal metabolism, which are strictly defined (adult, non-reproductive, postabsorptive animals resting in a thermoneutral environment during the inactive circadian phase). Similarly, a positive correlation between Mb and body temperature (Tb) and between Tb and mass-independent BMR contributes to elevation of b. While not strictly a defined condition for the measurement of BMR, the normalisation of BMR measurements to a common Tb (36.2 degrees C) to achieve standard metabolic rate (SMR) further reduces the CV of the relationship. Clearly the value of the exponent depends on the conditions under which the data are selected. The exponent for true BMR is 0.686 (+/-0.014), Tb normalised SMR is 0.675 (+/-0.013) and RMRt is 0.712 (+/-0.013).
TL;DR: Of all the known epilepsy genes SCN1A is currently the most clinically relevant, with the largest number of epilepsy related mutations so far characterized, and some clustering of mutations is observed in the C‐terminus and the loops between segments 5 and 6 of the first three domains of the protein.
Abstract: SCN1A is part of the SCN1A-SCN2A-SCN3A gene cluster on chromosome 2q24 that encodes for alpha pore forming subunits of sodium channels. The 26 exons of SCN1A are spread over 100 kb of genomic DNA. Genetic defects in the coding sequence lead to generalized epilepsy with febrile seizures plus (GEFS+) and a range of childhood epileptic encephalopathies of varied severity (e.g., SMEI). All published mutations are collated. More than 100 novel mutations are spread throughout the gene with the more debilitating usually de novo. Some clustering of mutations is observed in the C-terminus and the loops between segments 5 and 6 of the first three domains of the protein. Functional studies so far show no consistent relationship between changes to channel properties and clinical phenotype. Of all the known epilepsy genes SCN1A is currently the most clinically relevant, with the largest number of epilepsy related mutations so far characterized.
TL;DR: The results suggest that JARID1C mutations are a relatively common cause of XLMR and that this gene might play an important role in human brain function.
Abstract: In families with nonsyndromic X-linked mental retardation (NS-XLMR), >30% of mutations seem to cluster on proximal Xp and in the pericentric region. In a systematic screen of brain-expressed genes from this region in 210 families with XLMR, we identified seven different mutations in JARID1C, including one frameshift mutation and two nonsense mutations that introduce premature stop codons, as well as four missense mutations that alter evolutionarily conserved amino acids. In two of these families, expression studies revealed the almost complete absence of the mutated JARID1C transcript, suggesting that the phenotype in these families results from functional loss of the JARID1C protein. JARID1C (Jumonji AT-rich interactive domain 1C), formerly known as "SMCX," is highly similar to the Y-chromosomal gene JARID1D/SMCY, which encodes the H-Y antigen. The JARID1C protein belongs to the highly conserved ARID protein family. It contains several DNA-binding motifs that link it to transcriptional regulation and chromatin remodeling, processes that are defective in various other forms of mental retardation. Our results suggest that JARID1C mutations are a relatively common cause of XLMR and that this gene might play an important role in human brain function.
TL;DR: Evidence is provided of a methamphetamine withdrawal syndrome that can be categorized into two phases, the acute phase lasting 7-10 days during which overall symptom severity declined in a linear pattern from a high initial peak, and a subacute phase lasting at least a further 2 weeks.
Abstract: Aims To characterize the natural history of methamphetamine withdrawal during the first 3 weeks of abstinence. Design Cross-sectional study with comparison group. Setting A substance use treatment facility in Chiang Mai Province, Thailand. Participants The sample comprised 21 in-patients undergoing treatment for methamphetamine dependence. Nine age- and sex-matched non-dependent individuals provided comparison data. Measurements Instruments including: the Amphetamine Withdrawal Ques- tionnaire, a modified version of the Cocaine Selective Severity Assessment, Clin- ical Global Impression scale and the St Mary's Hospital Sleep Questionnaire were completed daily for the first 3 weeks of abstinence. Findings Methamphetamine withdrawal severity declined from a high initial peak within 24 hours of the last use of amphetamines reducing to near control levels by the end of the first week of abstinence (the acute phase). The acute phase of amphetamine withdrawal was characterized by increased sleeping and eating, a cluster of depression-related symptoms and less severely, anxiety and craving-related symptoms. Following the acute withdrawal phase most with- drawal symptoms remained stable and at low levels for the remaining 2 weeks of abstinence. Conclusions This study has provided evidence of a methamphetamine with- drawal syndrome that can be categorized into two phases, the acute phase last- ing 7-10 days during which overall symptom severity declined in a linear pattern from a high initial peak, and a subacute phase lasting at least a further 2 weeks.
TL;DR: A developmental framework of evidence-based practice is presented that builds and expands on the work of leaders in the field ofevidence-based healthcare; is contextualised; is inclusive of diverse forms of evidence; and incorporates understandings of knowledge transfer and utilisation.
Abstract: Evidence-based healthcare as it is contemporarily conceived is based on the view that clinical decisions should be based on the best available scientific evidence but recognising patient preferences, the context of healthcare and the judgement of the clinician. The ongoing debate on the nature of evidence for practice across all of the health professions is influenced by the experience of clinicians in everyday practice who, in using the evidence, assert that there are diverse sources of research-based and non-research-based evidence and that the process of evidence-based practice should be placed within a broader context that is grounded in practice; recognises different evidentiary bases; and is directed towards improving global health across vasty different practice contexts. We present a developmental framework of evidence-based practice that builds and expands on the work of leaders in the field of evidence-based healthcare; is contextualised; is inclusive of diverse forms of evidence; and incorporates understandings of knowledge transfer and utilisation. The conceptual model attempts to situate healthcare evidence and its role and use within the complexity of practice settings globally.
TL;DR: These results are the first to demonstrate that oocyte-secreted factors, and particularly BMP15 and BMP6, maintain the low incidence of cumulus cell apoptosis by establishing a localized gradient of bone morphogenetic proteins.
Abstract: Paracrine factors secreted by the oocyte regulate a broad range of cumulus cell functions. Characteristically, cumulus cells have a low incidence of apoptosis and we proposed that this is due to oocyte-secreted factors acting in an anti-apoptotic manner. Bovine cumulus-oocyte complexes (COC) were aspirated from abattoir-derived ovaries and oocytectomized (OOX) by microsurgical removal of the oocyte. OOX were treated with doses of either denuded oocytes (DO) or various growth factors for 24 hours (+/- rFSH; 0.1 IU/ml). Proportions of apoptotic cumulus cells were assessed using TUNEL and laser confocal scanning microscopy followed by image analysis. Quantification of Bcl-2 and Bax proteins in OOX was undertaken by western analysis. Oocyte removal led to a significant increase in cumulus cell apoptosis compared with COC controls (35% versus 9% TUNEL positive, respectively; P<0.001). Levels of OOX apoptosis were significantly reversed (P<0.001) in a dose-dependent manner when co-cultured with oocytes. Furthermore, the anti-apoptotic effect of oocyte-secreted factors followed a gradient from the site of the oocyte(s). Growth differentiation factor 9 (GDF9) had no significant effect on cumulus cell apoptosis. By contrast, cumulus cell apoptosis was significantly (P<0.001) reduced by bone morphogenetic proteins (BMP) 15, 6 or 7. Accordingly, levels of anti-apoptotic Bcl-2 were high in OOX+DO and OOX+BMP15 and low with OOX+GDF9 or OOX alone, whereas the reverse was observed for pro-apoptotic Bax. DO, BMP15 and BMP6 were also able to protect cumulus cells from undergoing apoptosis induced by staurosporine. FSH partially prevented apoptosis in all treatment groups (P<0.001). Follistatin and a BMP6 neutralizing antibody, which antagonized the anti-apoptotic effects of BMP15 and BMP6, respectively, whether alone or combined, blocked approximately 50% of the anti-apoptotic actions of oocytes. These results are the first to demonstrate that oocyte-secreted factors, and particularly BMP15 and BMP6, maintain the low incidence of cumulus cell apoptosis by establishing a localized gradient of bone morphogenetic proteins.
TL;DR: In this article, the performance of various turbulence, combustion, and chemical kinetic models in predicting the JHC flames was evaluated using the eddy-dissipation concept (EDC) solver.
Posted Content•
TL;DR: In this paper, the authors explored the effects of three unique intangibility dimensions on a consumer's ability to evaluate goods and services, and the perceived risk associated with the transaction.
Abstract: Intangibility has long been studied as a unidimensional construct with the focus being placed upon the physical element. This paper explores the effects of three unique intangibility dimensions on a consumer’s ability to evaluate goods and services, and the perceived risk (PR) associated with the transaction. The authors examine these relationships in purchase environments that include both traditional bricks-and-mortar retailers and the Internet. Their investigation further incorporates prior knowledge as a moderating factor into the proposed framework. This allows for a thorough comparison of the effects and relationships that exist between intangibility and its consequences in general, evaluation difficulty (ED) and perceived risk (PR) in particular. The authors develop hypotheses pertaining to the proposed model and test them with two experiments. The empirical results are broadly supportive of the hypotheses. Theoretical and managerial implications to the services marketing literature are discussed.
TL;DR: There is a need for both increased monitoring data for toxins in drinking water and epidemiological studies on adverse health effects in exposed populations to clarify the extent of the health risk.
Abstract: Cyanobacterial toxins have caused human poisoning in the Americas, Europe and Australia. There is accumulating evidence that they are present in treated drinking water supplies when cyanobacterial blooms occur in source waters. With increased population pressure and depleted groundwater reserves, surface water is becoming more used as a raw water source, both from rivers and lakes/reservoirs. Additional nutrients in water which arise from sewage discharge, agricultural run-off or storm water result in overabundance of cyanobacteria, described as a ‘water bloom’. The majority of cyanobacterial water-blooms are of toxic species, producing a diversity of toxins. The most important toxins presenting a risk to the human population are the neurotoxic alkaloids (anatoxins and paralytic shellfish poisons), the cyclic peptide hepatotoxins (microcystins) and the cytotoxic alkaloids (cylindrospermopsins). At the present time the only cyanobacteral toxin family that have been internationally assessed for health risk by the WHO are the microcystins, which cause acute liver injury and are active tumour promoters. Based on sub-chronic studies in rodents and pigs, a provisional Guideline Level for drinking water of 1μg/L of microcystin-LR has been determined. This has been adopted in legislation in countries in Europe, South America and Australasia. This may be revised in the light of future teratogenicity, reproductive toxicity and carcinogenicity studies. The other cyanobacterial toxin which has been proposed for detailed health risk assessment is cylindrospermopsin, a cytotoxic compound which has marked genotoxicity, probable mutagenicity, and is a potential carcinogen. This toxin has caused human poisoning from drinking water, and occurs in water supplies in the USA, Europe, Asia, Australia and South America. An initial health risk assessment is presented with a proposed drinking water Guideline Level of 1μg/L. There is a need for both increased monitoring data for toxins in drinking water and epidemiological studies on adverse health effects in exposed populations to clarify the extent of the health risk.
TL;DR: Survival time may be enhanced by strong social networks among older Australians, and these may be important in lengthening survival.
Abstract: Study objectives: To examine if social networks with children, relatives, friends, and confidants predict survival in older Australians over 10 years after controlling for a range of demographic, health, and lifestyle variables.
Design: Prospective longitudinal cohort study (the Australian longitudinal study of aging)
Setting: Adelaide, South Australia.
Participants: 1477 persons aged 70 years or more living in the community and residential care facilities.
Main results: After controlling for a range of demographic, health, and lifestyle variables, greater networks with friends were protective against mortality in the 10 year follow up period. The hazard ratio for participants in the highest tertile of friends networks compared with participants in the lowest group was 0.78 (95%CI 0.65 to 0.92). A smaller effect of greater networks with confidants (hazard ratio = 0.84; 95%CI = 0.71 to 0.98) was seen. The effects of social networks with children and relatives were not significant with respect to survival over the following decade.
Conclusions: Survival time may be enhanced by strong social networks. Among older Australians, these may be important in lengthening survival.