Necrotrophic growth of legionella pneumophila

This study examined whether Legionella pneumophila is able to thrive on heat-killed microbial cells (necrotrophy) present in biofilms or heat-treated water systems. Quantification by means of plate counting, real-time PCR, and flow cytometry demonstrated necrotrophic growth of L. pneumophila in water after 96 h, when at least 100 dead cells are available to one L. pneumophila cell. Compared to the starting concentration of L. pneumophila, the maximum observed necrotrophic growth was 1.89 log units for real-time PCR and 1.49 log units for plate counting. The average growth was 1.57 ± 0.32 log units (n = 5) for real-time PCR and 1.14 ± 0.35 log units (n = 5) for plate counting. Viability staining and flow cytometry showed that the fraction of living cells in the L. pneumophila population rose from the initial 54% to 82% after 96 h. Growth was measured on heat-killed Pseudomonas putida, Escherichia coli, Acanthamoeba castellanii, Saccharomyces boulardii, and a biofilm sample. Gram-positive organisms did not result in significant growth of L. pneumophila, probably due to their robust cell wall structure. Although necrotrophy showed lower growth yields compared to replication within protozoan hosts, these findings indicate that it may be of major importance in the environmental persistence of L. pneumophila. Techniques aimed at the elimination of protozoa or biofilm from water systems will not necessarily result in a subsequent removal of L. pneumophila unless the formation of dead microbial cells is minimized

How to assess success of treatment when using multiple doses: the case of misoprostol for medical abortion.

Background: The assessment of treatment success in clinical trials when multiple (repeated) doses (courses) are involved is quite common, for example, in the case of infertility treatment with assisted reproductive technology (ART), and medical abortion using misoprostol alone or in combination with mifepristone. Under these or similar circumstances, most researchers assess success using binomial proportions after a certain number of consecutive doses, and some have used survival analysis. In this paper we discuss the main problems in using binomial proportions to summarize (the overall) efficacy after two or more consecutive doses of the relevant treatment, particularly for the case of misoprostol in medical abortion studies. We later discuss why the survival analysis is best suited under these circumstances, and illustrate this by using simulated data. Methods: The formulas required for the binomial proportion and survival analysis (without and with competing risks) approaches are summarized and analytically compared. Additionally, numerical results are computed and compared between the two approaches, for several theoretical scenarios. Results: The main conceptual limitations of the binomial proportion approach are identified and discussed, caused mainly by the presence of censoring and competing risks, and it is demonstrated how survival analysis can solve these problems. In general, the binomial proportion approach tends to underestimate the “real” success rate, and tends to overestimate the corresponding standard error. Conclusions: Depending on the rates of censored observations or competing events between repeated doses of the treatment, the bias of the binomial proportion approach as compared to the survival analysis approaches varies; however, the use of the binomial approach is unjustified as the survival analysis options are well known and available in multiple statistical packages. Our conclusions also apply to other situations where success is estimated after multiple (repeated) doses (courses) of the treatment

Achieving Pregnancy Safely in HIV-Affected Individuals and Couples: An Important Strategy to Eliminate HIV Transmission From Mother-To-Child and Between Sexual Partners

HIV-infected individuals are living longer, more productive lives. HIV-affected individuals and couples experience personal and social desires to reproduce for all the same reasons as uninfected individuals and couples,1 and thus require safe reproductive options. HIV prevention interventions often do not consider the childbearing desires of HIV-affected individuals or couples, especially in low- and middle-income countries (LMICs). Failure to assist women with desired fertility can contribute to continued HIV transmission and must be addressed within national elimination of mother-to-child transmission (eMTCT) strategies. A human rights perspective suggests that HIV-affected couples* should have the same ability to choose if and when to have children as HIV-unaffected couples, including access to pre-pregnancy counseling, contraceptives, and, when needed, abortion services. This holistic view includes assistance in mitigating HIV transmission risk when children are desired. In high-income countries, HIV-affected individuals and couples have access to an array of options: (1) treatment of the HIV-infected partner as prevention of transmission to the uninfected partner in conjunction with timed condomless intercourse2**; (2) preexposure prophylaxis (PrEP) for the uninfected partner3; (3) assisted reproductive services, including timed vaginal insemination and sperm washing with intrauterine insemination or in-vitro fertilization4,5 4,5; (4) sperm donation; and (5) adoption.1,6 1,6 In contrast, access to methods of becoming pregnant in LMICs are limited by cost, availability, and sometimes a lack of appreciation by policymakers of the desires and rights of HIV-affected individuals/couples to have children safely. Simple fertility methods may not be discussed as a component of routine HIV care and treatment counseling due to a lack of awareness or knowledge about their safety, affordability, or efficacy.7 To enhance the armamentarium of HIV prevention and reproductive services to achieve zero perinatal and sexual transmission, “safer conception”, and fertility services should be integrated into existing PMTCT strategies. The existing four-pronged prevention of mother-to-child transmission (PMTCT) strategy, developed by the World Health Organization (WHO), includes (1) prevention of HIV in women of reproductive age; (2) prevention of unintended pregnancy in women with HIV; (3) prevention of HIV transmission from mother to child; and (4) the provision of ongoing care and support to mothers, their children, and their families.8 All four prongs are rooted in prevention of sexual and perinatal HIV transmission, HIV testing, use of ART for mothers and infants, exclusive breastfeeding, and access to contraceptive services. The continuum of care services are included within the third WHO prong, including antenatal, intrapartum, and postpartum/postnatal health care services (Fig. 1). However, provision of education and clinical services for achieving pregnancy safely is not uniquely addressed in the current WHO eMTCT strategy,8 and we believe that they should be included within the continuum of care services of the third prong of the strategy that addresses: “prevention of HIV transmission from mother to child.

Cluster coherent potential approximation for electronic structure of disordered alloys

We extend the single-site coherent potential approximation (CPA) to include the effects of non-local disorder correlations (alloy short-range order) on the electronic structure of random alloy systems. This is achieved by mapping the original Anderson disorder problem to that of a selfconsistently embedded cluster. This cluster problem is then solved using the equations of motion technique. The CPA is recovered for cluster size $N_{c}=1$, and the disorder averaged density-of-states (DOS) is always positive definite. Various new features, compared to those observed in CPA, and related to repeated scattering on pairs of sites, reflecting the effect of SRO are clearly visible in the DOS. It is explicitly shown that the cluster-CPA method always yields positive-definite DOS. Anderson localization effects have been investigated within this approach. In general, we find that Anderson localization sets in before band splitting occurs, and that increasing partial order drives a continuous transition from an Anderson insulator to an incoherent metal.Comment: 7 pages, 6 figures. submitted to PR

Clinical relevance of Aspergillus isolation from respiratory tract samples in critically ill patients

INTRODUCTION: The diagnosis of invasive pulmonary aspergillosis, according to the criteria as defined by the European Organisation for the Research and Treatment of Cancer/Mycoses Study Group (EORTC/MSG), is difficult to establish in critically ill patients. The aim of this study is to address the clinical significance of isolation of Aspergillus spp. from lower respiratory tract samples in critically ill patients on the basis of medical and radiological files using an adapted diagnostic algorithm to discriminate proven and probable invasive pulmonary aspergillosis from Aspergillus colonisation. METHODS: Using a historical cohort (January 1997 to December 2003), all critically ill patients with respiratory tract samples positive for Aspergillus were studied. In comparison to the EORTC/MSG criteria, a different appreciation was given to radiological features and microbiological data, including semiquantitative cultures and direct microscopic examination of broncho-alveolar lavage samples. RESULTS: Over a 7 year period, 172 patients were identified with a positive culture. Of these, 83 patients were classified as invasive aspergillosis. In 50 of these patients (60%), no high risk predisposing conditions (neutropenia, hematologic cancer and stem cell or bone marrow transplantation) were found. Typical radiological imaging (halo and air-crescent sign) occurred in only 5% of patients. In 26 patients, histological examination either by ante-mortem lung biopsy (n = 10) or necropsy (n = 16) was performed, allowing a rough estimation of the predictive value of the diagnostic algorithm. In all patients with histology, all cases of clinical probable pulmonary aspergillosis were confirmed (n = 17). Conversely, all cases classified as colonisation had negative histology (n = 9). CONCLUSION: A respiratory tract sample positive for Aspergillus spp. in the critically ill should always prompt further diagnostic assessment, even in the absence of the typical hematological and immunological host risk factors. In a minority of patients, the value of the clinical diagnostic algorithm was confirmed by histological findings, supporting its predictive value. The proposed diagnostic algorithm needs prospective validation

Early detection of cervical cancer in western Kenya : determinants of healthcare providers performing a gynaecological examination for abnormal vaginal discharge or bleeding

Background In western Kenya, women often present with late-stage cervical cancer despite prior contact with the health care system. The aim of this study was to predict primary health care providers' behaviour in examining women who present with abnormal discharge or bleeding. Methods This was a cross-sectional survey using the theory of planned behaviour (TPB). A sample of primary health care practitioners in western Kenya completed a 59-item questionnaire. Structural equation modelling was used to identify the determinants of providers' intention to perform a gynaecological examination. Bivariate analysis was conducted to investigate the relationship between the external variables and intention. Results Direct measures of subjective norms (DMSN), direct measures of perceived behavioural control (DMPBC), and indirect measures of attitude predicted the intention to examine patients. Negative attitudes toward examining women had a suppressor effect on the prediction of health workers' intentions. However, the predictors of intention with the highest coefficients were the external variables being a nurse (beta = 0.32) as opposed to a clinical officer and workload of attending less than 50 patients per day (beta = 0.56). In bivariate analysis with intention to perform a gynaecological examination, there was no evidence that working experience, being female, having a lower workload, or being a private practitioner were associated with a higher intention to conduct vaginal examinations. Clinical officers and nurses were equally likely to examine women. Conclusions The TPB is a suitable theoretical basis to predict the intention to perform a gynaecological examination. Overall, the model predicted 47% of the variation in health care providers' intention to examine women who present with recurrent vaginal bleeding or discharge. Direct subjective norms (health provider's conformity with what their colleagues do or expect them to do), PBC (providers need to feel competent and confident in performing examinations in women), and negative attitudes toward conducting vaginal examination accounted for the most variance. External variables in this study also contributed to the overall variance. As the model in this study could not explain 53% of the variance, investigating other external variables that influence the intention to examine women should be undertaken

Early detection of cervical cancer in western Kenya: determinants of healthcare providers performing a gynaecological examination for abnormal vaginal discharge or bleeding

Background: In western Kenya, women often present with late-stage cervical cancer despite prior contact with the health care system. The aim of this study was to predict primary health care providers’ behaviour in examining women who present with abnormal discharge or bleeding. Methods: This was a cross-sectional survey using the theory of planned behaviour (TPB). A sample of primary health care practitioners in western Kenya completed a 59-item questionnaire. Structural equation modelling was used to identify the determinants of providers’ intention to perform a gynaecological examination. Bivariate analysis was conducted to investigate the relationship between the external variables and intention. Results: Direct measures of subjective norms (DMSN), direct measures of perceived behavioural control (DMPBC), and indirect measures of attitude predicted the intention to examine patients. Negative attitudes toward examining women had a suppressor effect on the prediction of health workers’ intentions. However, the predictors of intention with the highest coefficients were the external variables being a nurse (β = 0.32) as opposed to a clinical officer and workload of attending less than 50 patients per day (β = 0.56). In bivariate analysis with intention to perform a gynaecological examination, there was no evidence that working experience, being female, having a lower workload, or being a private practitioner were associated with a higher intention to conduct vaginal examinations. Clinical officers and nurses were equally likely to examine women. Conclusions: The TPB is a suitable theoretical basis to predict the intention to perform a gynaecological examination. Overall, the model predicted 47% of the variation in health care providers’ intention to examine women who present with recurrent vaginal bleeding or discharge. Direct subjective norms (health provider’s conformity with what their colleagues do or expect them to do), PBC (providers need to feel competent and confident in performing examinations in women), and negative attitudes toward conducting vaginal examination accounted for the most variance. External variables in this study also contributed to the overall variance. As the model in this study could not explain 53% of the variance, investigating other external variables that influence the intention to examine women should be undertaken

Effect of neon plasma pre-irradiation on surface morphology and deuterium retention of tungsten

Neon and deuterium plasma irradiation of polycrystalline tungsten targets have been performed at high fluxes of ∼1024&nbsp;ions&nbsp;m−2&nbsp;s−1 to study the interaction of neon with tungsten and the influence of neon on deuterium retention. Tungsten exposure to neon plasma leads to the formation of wavy nanostructures on the surface. Subsequent exposure to high-flux deuterium plasma leads to blister formation of micrometer size on top of the wavy structures. The total deuterium retention is decreased by neon pre-irradiation for all surface temperatures used in the present experiments. It is suggested that a barrier of trapped Ne is formed that interrupts the D transport and reduces D retention.</p