Fetal exposure to bisphenol A as a risk factor for the development of childhood asthma: an animal model study

<p>Abstract</p> <p>Background</p> <p>The prevalence of asthma in industrialized countries has been increasing dramatically and asthma is now the most common chronic disease of children in the United States. The rapidity of the increase strongly suggests that changes in environmental exposures are the likely cause of this epidemic. Further, the early onset of allergic manifestations suggests that these exposures may act on the prenatal development of the immune system. We have focused on the potential effects of bisphenol A (BPA), a chemical pollutant with one of the largest productions, on the development of childhood asthma. We have reported that perinatal BPA exposure promotes the development of allergic asthma in a mouse model. The current study was designed to identify a critical period of BPA exposure and to begin elucidating the mechanisms for this susceptibility.</p> <p>Methods</p> <p>Female BALB/c mice received 10 micro g/ml BPA in their drinking water from one week before pregnancy until the end of the study. Some of the pups were transferred in the first 48 h of life from their BPA-loaded mother to an unexposed mother, or vice versa. Half of the pups were sensitized with a low dose of the experimental allergen ovalbumin (OVA), the rest received PBS as an unsensitized controls. On day 22, the pups were challenged by inhalations of ovalbumin or PBS followed by quantification of eosinophils in and hyperreactivity of their airways, major indicators of experimental asthma in this classical mouse model. Hepatic expression of two isoforms of UDP-glucuronosyltransferase (Ugt) was quantified by quantitative RT-PCR at various ages.</p> <p>Results</p> <p>Pups exposed to BPA in utero and through breast milk, or in utero only, displayed an asthma phenotype in response to their "suboptimal" allergic sensitization, whereas, pups only exposed to BPA postnatally from breast milk, did not. The expression of Ugt2b1, an isoform related to BPA clearance in rats, was not detectable in mouse fetuses and newborn pups, but increased by day 5 and approached adult levels by day 25.</p> <p>Conclusions</p> <p>Prenatal exposures that produce environmentally relevant burdens of BPA, followed by postnatal allergic sensitization and challenges, promote the development of experimental allergic asthma. Delayed expression of BPA-metabolizing enzymes may explain, at least in part, the enhanced fetal susceptibility to this common environmental contaminant.</p

Quantitative measurements of inequality in geographic accessibility to pediatric care in Oita Prefecture, Japan: Standardization with complete spatial randomness

<p>Abstract</p> <p>Background</p> <p>A quantitative measurement of inequality in geographic accessibility to pediatric care as well as that of mean distance or travel time is very important for priority setting to ensure fair access to pediatric facilities. However, conventional techniques for measuring inequality is inappropriate in geographic settings. Since inequality measures of access distance or travel time is strongly influenced by the background geographic distribution patterns, they cannot be directly used for regional comparisons of geographic accessibility. The objective of this study is to resolve this issue by using a standardization approach.</p> <p>Methods</p> <p>Travel times to the nearest pediatric care were calculated for all children in Oita Prefecture, Japan. Relative mean differences were considered as the inequality measure for secondary medical service areas, and were standardized with an expected value estimated from a Monte Carlo simulation based on complete spatial randomness.</p> <p>Results</p> <p>The observed mean travel times in the area considered averaged 4.50 minutes, ranging from 1.83 to 7.02 minutes. The mean of the observed inequality measure was 1.1, ranging from 0.9 to 1.3. The expected values of the inequality measure varied according to the background geographic distribution pattern of children, which ranged from 0.3 to 0.7. After standardizing the observed inequality measure with the expected one, we found that the ranks of the inequality measure were reversed for the observed areas.</p> <p>Conclusions</p> <p>Using the indicator proposed in this paper, it is possible to compare the inequality in geographic accessibility among regions. Such a comparison may facilitate priority setting in health policy and planning.</p

Ceramic Water Filter for Point-Of-Use Water Treatment in Developing Countries: Principles, Challenges and Opportunities

Drinking water source contamination poses a great threat to human health in developing countries. Point-of-use (POU) water treatment techniques, which improve drinking water quality at the household level, offer an affordable and convenient way to obtain safe drinking water and thus can reduce the outbreaks of waterborne diseases. Ceramic water filters (CWFs), fabricated from locally sourced materials and manufactured by local labor, are one of the most socially acceptable POU water treatment technologies because of their effectiveness, low-cost and ease of use. This review concisely summarizes the critical factors that influence the performance of CWFs, including (1) CWF manufacturing process (raw material selection, firing process, silver impregnation), and (2) source water quality. Then, an in-depth discussion is presented with emphasis on key research efforts to address two major challenges of conventional CWFs, including (1) simultaneous increase of filter flow rate and bacterial removal efficiency, and (2) removal of various concerning pollutants, such as viruses and metal(loid)s. To promote the application of CWFs, future research directions can focus on: (1) investigation of pore size distribution and pore structure to achieve higher flow rates and effective pathogen removal by elucidating pathogen transport in porous ceramic and adjusting manufacture parameters; and (2) exploration of new surface modification approaches with enhanced interaction between a variety of contaminants and ceramic surfaces

Phylogeography and Molecular Epidemiology of Yersinia pestis in Madagascar

Plague, caused by the bacterium Yersinia pestis, has been a problem in Madagascar since it was introduced in 1898. It mainly affects the central highlands, but also has caused several large outbreaks in the port city of Mahajanga, after it was reintroduced there in the 1990s. Despite its prevalence, the genetic diversity and related geographic distribution of different genetic groups of Y. pestis in Madagascar has been difficult to study due to the great genetic similarity among isolates. We subtyped a set of Malagasy isolates and identified two major genetic groups that were subsequently divided into 11 and 4 subgroups, respectively. Y. pestis appears to be maintained in several geographically separate subpopulations. There is also evidence for multiple long distance transfers of Y. pestis, likely human mediated. Such transfers have resulted in the reintroduction and establishment of plague in the port city of Mahajanga where there is evidence for multiple transfers both from and to the central highlands. The maintenance and spread of Y. pestis in Madagascar is a dynamic and highly active process that relies on the natural cycle between the primary host, the black rat, and its flea vectors as well as human activity

Assessing the Quality of Clinical Teachers: A Systematic Review of Content and Quality of Questionnaires for Assessing Clinical Teachers

BACKGROUND: Learning in a clinical environment differs from formal educational settings and provides specific challenges for clinicians who are teachers. Instruments that reflect these challenges are needed to identify the strengths and weaknesses of clinical teachers. OBJECTIVE: To systematically review the content, validity, and aims of questionnaires used to assess clinical teachers. DATA SOURCES: MEDLINE, EMBASE, PsycINFO and ERIC from 1976 up to March 2010. REVIEW METHODS: The searches revealed 54 papers on 32 instruments. Data from these papers were documented by independent researchers, using a structured format that included content of the instrument, validation methods, aims of the instrument, and its setting. Results : Aspects covered by the instruments predominantly concerned the use of teaching strategies (included in 30 instruments), supporter role (29), role modeling (27), and feedback (26). Providing opportunities for clinical learning activities was included in 13 instruments. Most studies referred to literature on good clinical teaching, although they failed to provide a clear description of what constitutes a good clinical teacher. Instrument length varied from 1 to 58 items. Except for two instruments, all had to be completed by clerks/residents. Instruments served to provide formative feedback ( instruments) but were also used for resource allocation, promotion, and annual performance review (14 instruments). All but two studies reported on internal consistency and/or reliability; other aspects of validity were examined less frequently. CONCLUSIONS: No instrument covered all relevant aspects of clinical teaching comprehensively. Validation of the instruments was often limited to assessment of internal consistency and reliability. Available instruments for assessing clinical teachers should be used carefully, especially for consequential decisions. There is a need for more valid comprehensive instruments

Immunoglobulin Genomics in the Guinea Pig (Cavia porcellus)

In science, the guinea pig is known as one of the gold standards for modeling human disease. It is especially important as a molecular and cellular biology model for studying the human immune system, as its immunological genes are more similar to human genes than are those of mice. The utility of the guinea pig as a model organism can be further enhanced by further characterization of the genes encoding components of the immune system. Here, we report the genomic organization of the guinea pig immunoglobulin (Ig) heavy and light chain genes. The guinea pig IgH locus is located in genomic scaffolds 54 and 75, and spans approximately 6,480 kb. 507 VH segments (94 potentially functional genes and 413 pseudogenes), 41 DH segments, six JH segments, four constant region genes (μ, γ, ε, and α), and one reverse δ remnant fragment were identified within the two scaffolds. Many VH pseudogenes were found within the guinea pig, and likely constituted a potential donor pool for gene conversion during evolution. The Igκ locus mapped to a 4,029 kb region of scaffold 37 and 24 is composed of 349 Vκ (111 potentially functional genes and 238 pseudogenes), three Jκ and one Cκ genes. The Igλ locus spans 1,642 kb in scaffold 4 and consists of 142 Vλ (58 potentially functional genes and 84 pseudogenes) and 11 Jλ -Cλ clusters. Phylogenetic analysis suggested the guinea pig’s large germline VH gene segments appear to form limited gene families. Therefore, this species may generate antibody diversity via a gene conversion-like mechanism associated with its pseudogene reserves