Knowledge, attitudes, practices and prevalence of hepatitis B and C and hepatitis B vaccination coverage among public sector healthcare workers in Cambodia

Healthcare workers (HCWs) are a key population at high risk for hepatitis B (HBV) and hepatitis C (HCV) infections. We aim to study HBV vaccination coverage, seroprevalence, knowledge, attitudes, and practices towards HBV and HCV infections among HCWs in public sector in Cambodia. A nationally representative cross-sectional study was implemented in 2019, among Cambodian HCWs. A standardized questionnaire was administered to randomly selected HCWs whose blood was then sampled. We used univariate and multivariate regression to determine predictors of outcomes. Among 755 participants, we found 4.9% positive HBsAg and 2.3% positive anti-HCV Ab. HBV vaccination coverage was 59.3%. Lack of knowledge was found on the route of transmission, HBV vaccination, diagnosis and treatment of HBV and HCV. 67% of HCWs thought that all patients should be screened for HBV and HCV and about 30% of them would refuse to take care of infected patients. 58% of HCWs always recapped the needle after use. In univariate analysis, older age-group (> 50 years) is more likely to have positive anti-HCV (OR: 9.48; 95% CI: 2.36-38.18). HCWs who were younger, female or having higher education or having ever been tested, were more likely to have gotten HBV vaccinated. Multivariate analysis reconfirmed these predictors of getting vaccinated. Study findings indicated an urgent need of a national policy for Cambodian HCWs given the high prevalence of hepatitis among this group. Policy should include an effective in-service training program to improve knowledge and practices, a testing and vaccination program for HCWs and it should emphasize stigma intervention towards people living with HBV/HCV.

The genomic landscape of swine influenza A viruses in Southeast Asia

Swine are a primary source for the emergence of pandemic influenza A viruses. The intensification of swine production, along with global trade, has amplified the transmission and zoonotic risk of swine influenza A virus (swIAV). Effective surveillance is essential to uncover emerging virus strains; however gaps remain in our understanding of the swIAV genomic landscape in Southeast Asia. More than 4,000 nasal swabs were collected from pigs in Cambodia, yielding 72 IAV-positive samples by RT-qPCR and 45 genomic sequences. We unmasked the cocirculation of multiple lineages of genetically diverse swIAV of pandemic concern. Genomic analyses revealed a novel European avian-like H1N2 swIAV reassortant variant with North American triple reassortant internal genes, that emerged approximately seven years before its first detection in pigs in 2021. Using phylogeographic reconstruction, we identified south central China as the dominant source of swine viruses disseminated to other regions in China and Southeast Asia. We also identified nine distinct swIAV lineages in Cambodia, which diverged from their closest ancestors between two and 15 B.P., indicating significant undetected diversity in the region, including reverse zoonoses of human H1N1/2009 pandemic and H3N2 viruses. A similar period of cryptic circulation of swIAVs occurred in the decades before the H1N1/2009 pandemic. The hidden diversity of swIAV observed here further emphasizes the complex underlying evolutionary processes present in this region, reinforcing the importance of genomic surveillance at the human-swine interface for early warning of disease emergence to avoid future pandemics.

In-hospital mortality risk stratification in children aged under 5 years with pneumonia with or without pulse oximetry: A secondary analysis of the Pneumonia REsearch Partnership to Assess WHO REcommendations (PREPARE) dataset

OBJECTIVES

We determined the pulse oximetry benefit in pediatric pneumonia mortality risk stratification and chest-indrawing pneumonia in-hospital mortality risk factors.

METHODS

We report the characteristics and in-hospital pneumonia-related mortality of children aged 2-59 months who were included in the Pneumonia Research Partnership to Assess WHO Recommendations dataset. We developed multivariable logistic regression models of chest-indrawing pneumonia to identify mortality risk factors.

RESULTS

Among 285,839 children, 164,244 (57.5%) from hospital-based studies were included. Pneumonia case fatality risk (CFR) without pulse oximetry measurement was higher than with measurement (5.8%, 95% confidence interval [CI] 5.6-5.9% vs 2.1%, 95% CI 1.9-2.4%). One in five children with chest-indrawing pneumonia was hypoxemic (19.7%, 95% CI 19.0-20.4%), and the hypoxemic CFR was 10.3% (95% CI 9.1-11.5%). Other mortality risk factors were younger age (either 2-5 months [adjusted odds ratio (aOR) 9.94, 95% CI 6.67-14.84] or 6-11 months [aOR 2.67, 95% CI 1.71-4.16]), moderate malnutrition (aOR 2.41, 95% CI 1.87-3.09), and female sex (aOR 1.82, 95% CI 1.43-2.32).

CONCLUSION

Children with a pulse oximetry measurement had a lower CFR. Many children hospitalized with chest-indrawing pneumonia were hypoxemic and one in 10 died. Young age and moderate malnutrition were risk factors for in-hospital chest-indrawing pneumonia-related mortality. Pulse oximetry should be integrated in pneumonia hospital care for children under 5 years.

Assembling a global database of child pneumonia studies to inform WHO pneumonia management algorithm: Methodology and applications

Background

The existing World Health Organization (WHO) pneumonia case management guidelines rely on clinical symptoms and signs for identifying, classifying, and treating pneumonia in children up to 5 years old. We aimed to collate an individual patient-level data set from large, high-quality pre-existing studies on pneumonia in children to identify a set of signs and symptoms with greater validity in the diagnosis, prognosis, and possible treatment of childhood pneumonia for the improvement of current pneumonia case management guidelines.

Methods

Using data from a published systematic review and expert knowledge, we identified studies meeting our eligibility criteria and invited investigators to share individual-level patient data. We collected data on demographic information, general medical history, and current illness episode, including history, clinical presentation, chest radiograph findings when available, treatment, and outcome. Data were gathered separately from hospital-based and community-based cases. We performed a narrative synthesis to describe the final data set.

Results

Forty-one separate data sets were included in the Pneumonia Research Partnership to Assess WHO Recommendations (PREPARE) database, 26 of which were hospital-based and 15 were community-based. The PREPARE database includes 285 839 children with pneumonia (244 323 in the hospital and 41 516 in the community), with detailed descriptions of clinical presentation, clinical progression, and outcome. Of 9185 pneumonia-related deaths, 6836 (74%) occurred in children <1 year of age and 1317 (14%) in children aged 1-2 years. Of the 285 839 episodes, 280 998 occurred in children 0-59 months old, of which 129 584 (46%) were 2-11 months of age and 152 730 (54%) were males.

Conclusions

This data set could identify an improved specific, sensitive set of criteria for diagnosing clinical pneumonia and help identify sick children in need of referral to a higher level of care or a change of therapy. Field studies could be designed based on insights from PREPARE analyses to validate a potential revised pneumonia algorithm. The PREPARE methodology can also act as a model for disease database assembly.

Derivation and validation of a novel risk assessment tool to identify children aged 2–59 months at risk of hospitalised pneumonia-related mortality in 20 countries

Introduction

Existing risk assessment tools to identify children at risk of hospitalised pneumonia-related mortality have shown suboptimal discriminatory value during external validation. Our objective was to derive and validate a novel risk assessment tool to identify children aged 2–59 months at risk of hospitalised pneumonia-related mortality across various settings.

Methods

We used primary, baseline, patient-level data from 11 studies, including children evaluated for pneumonia in 20 low-income and middle-income countries. Patients with complete data were included in a logistic regression model to assess the association of candidate variables with the outcome hospitalised pneumonia-related mortality. Adjusted log coefficients were calculated for each candidate variable and assigned weighted points to derive the Pneumonia Research Partnership to Assess WHO Recommendations (PREPARE) risk assessment tool. We used bootstrapped selection with 200 repetitions to internally validate the PREPARE risk assessment tool.

Results

A total of 27 388 children were included in the analysis (mean age 14.0 months, pneumonia-related case fatality ratio 3.1%). The PREPARE risk assessment tool included patient age, sex, weight-for-age z-score, body temperature, respiratory rate, unconsciousness or decreased level of consciousness, convulsions, cyanosis and hypoxaemia at baseline. The PREPARE risk assessment tool had good discriminatory value when internally validated (area under the curve 0.83, 95% CI 0.81 to 0.84).

Conclusions

The PREPARE risk assessment tool had good discriminatory ability for identifying children at risk of hospitalised pneumonia-related mortality in a large, geographically diverse dataset. After external validation, this tool may be implemented in various settings to identify children at risk of hospitalised pneumonia-related mortality.

Nasopharyngeal Viral and Bacterial Co-Detection among Children from Low- and Middle-Income Countries with and without Pneumonia

The role of microbial coinfection in the pathogenesis of pneumonia in children is not well known. The aim of this work was to describe the prevalence of microorganism co-detection in nasopharyngeal samples (NPS) of pneumonia cases and control subjects and to study the potential association between nasopharyngeal microorganism co-detection and pneumonia. A case-control study was carried out from 2010 to 2014 in nine study sites located in low- or middle-income countries. The data from 888 children under 5 years of age with pneumonia (cases) and 870 children under 5 without pneumonia (controls) were analyzed. Nasopharyngeal samples were collected; reverse transcription polymerase chain reaction (RT-PCR) enabled the detection of five bacteria and 19 viruses. Multiple, mixed-effects logistic regression modeling was undertaken to evaluate the association between microorganism co-detection and pneumonia. A single Streptococcus pneumoniae colonization was observed in 15.2% of the controls and 10.1% of the cases (P = 0.001), whereas S. pneumoniae and a single virus co-detection was observed in 33.3% of the cases and in 14.6% of the controls (P < 0.001). Co-detections with rhinovirus, respiratory syncytial virus, parainfluenza virus, human metapneumovirus, and influenza virus were more frequent in the cases compared with the controls (P < 0.001) and were significantly associated with pneumonia in multiple regression analysis. The proportion of single virus detection without bacterial co-detection was not different between cases and controls (13.6% versus 11.3%, P = 0.13). This study suggests that coinfection of S. pneumoniae and certain viruses may play a role in the pathophysiology of pneumonia in children.

External validation of the RISC, RISC-Malawi, and PERCH clinical prediction rules to identify risk of death in children hospitalized with pneumonia

BACKGROUND

Existing scores to identify children at risk of hospitalized pneumonia-related mortality lack broad external validation. Our objective was to externally validate three such risk scores.

METHODS

We applied the Respiratory Index of Severity in Children (RISC) for HIV-negative children, the RISC-Malawi, and the Pneumonia Etiology Research for Child Health (PERCH) scores to hospitalized children in the Pneumonia REsearch Partnerships to Assess WHO REcommendations (PREPARE) data set. The PREPARE data set includes pooled data from 41 studies on pediatric pneumonia from across the world. We calculated test characteristics and the area under the curve (AUC) for each of these clinical prediction rules.

RESULTS

The RISC score for HIV-negative children was applied to 3574 children 0-24 months and demonstrated poor discriminatory ability (AUC = 0.66, 95% confidence interval (CI) = 0.58-0.73) in the identification of children at risk of hospitalized pneumonia-related mortality. The RISC-Malawi score had fair discriminatory value (AUC = 0.75, 95% CI = 0.74-0.77) among 17 864 children 2-59 months. The PERCH score was applied to 732 children 1-59 months and also demonstrated poor discriminatory value (AUC = 0.55, 95% CI = 0.37-0.73).

CONCLUSIONS

In a large external application of the RISC, RISC-Malawi, and PERCH scores, a substantial number of children were misclassified for their risk of hospitalized pneumonia-related mortality. Although pneumonia risk scores have performed well among the cohorts in which they were derived, their performance diminished when externally applied. A generalizable risk assessment tool with higher sensitivity and specificity to identify children at risk of hospitalized pneumonia-related mortality may be needed. Such a generalizable risk assessment tool would need context-specific validation prior to implementation in that setting.

Serotypes of Streptococcus pneumoniae in Children Aged <5 Years Hospitalized With or Without Pneumonia in Developing and Emerging Countries: A Descriptive, Multicenter Study

BACKGROUND

Improving knowledge regarding Streptococcus pneumoniae distribution in pneumonia cases is important to better target preventive and curative measures. The objective was to describe S. pneumoniae serotypes in children with or without pneumonia.

METHODS

It was a case-control study carried out in 8 developing and emerging countries between 2010 and 2014. Cases were children aged <5 years admitted to the hospital for pneumonia. Controls were children admitted for surgery or routine outpatient care.

RESULTS

In nasopharyngeal samples, S. pneumoniae were detected in 68.2% of the cases and 47.5% of the controls (P < .001). Nasopharyngeal carriage was associated with a higher risk of being a case in 6/8 study sites (adjusted odds ratio ranged from 0.71 [95% confidence interval [CI], .39-1.29; P = .26] in India [Pune/Vadu] to 11.86 [95% CI, 5.77-24.41; P < .001] in Mongolia). The 13-valent pneumococcal conjugate vaccine (PCV13) serotypes were more frequently detected in cases with nasopharyngeal carriage (67.1%) than in controls with nasopharyngeal carriage (54.6%), P < .001. Streptococcus pneumoniae was detected in blood by polymerase chain reaction in 8.3% of the cases. Of 34 cases with an S. pneumoniae serotype detected in blood, 27 (79%) had the same serotype in the nasopharyngeal sample.

CONCLUSIONS

The results confirm the assumption that the isolate carrying or causing disease in an individual is of the same serotype. Most serotypes independently associated with nasopharyngeal carriage or pneumonia are covered by PCV13, suggesting that increased PCV coverage would reduce the burden of S. pneumoniae-related pneumonia.

MALDI-TOF mass spectrometry for sub-typing of Streptococcus pneumoniae

Background

Serotyping of Streptococcus pneumoniae is important for monitoring of vaccine impact. Unfortunately, conventional and molecular serotyping is expensive and technically demanding. This study aimed to determine the ability of matrix-assisted laser desorption-ionisation time-of-flight (MALDI-TOF) mass spectrometry to discriminate between pneumococcal serotypes and genotypes (defined by global pneumococcal sequence cluster, GPSC). In this study, MALDI-TOF mass spectra were generated for a diverse panel of whole genome sequenced pneumococcal isolates using the bioMerieux VITEK MS in clinical diagnostic (IVD) mode. Discriminatory mass peaks were identified and hierarchical clustering was performed to visually assess discriminatory ability. Random forest and classification and regression tree (CART) algorithms were used to formally determine how well serotypes and genotypes were identified by MALDI-TOF mass spectrum.

Results

One hundred and ninety-nine pneumococci, comprising 16 serotypes and non-typeable isolates from 46 GPSC, were analysed. In the primary experiment, hierarchical clustering revealed poor congruence between MALDI-TOF mass spectrum and serotype. The correct serotype was identified from MALDI-TOF mass spectrum in just 14.6% (random forest) or 35.4% (CART) of 130 isolates. Restricting the dataset to the nine dominant GPSC (61 isolates / 13 serotypes), discriminatory ability improved slightly: the correct serotype was identified in 21.3% (random forest) and 41.0% (CART). Finally, analysis of 69 isolates of three dominant serotype-genotype pairs (6B-GPSC1, 19F-GPSC23, 23F-GPSC624) resulted in the correct serotype identification in 81.1% (random forest) and 94.2% (CART) of isolates.

Conclusions

This work suggests that MALDI-TOF is not a useful technique for determination of pneumococcal serotype. MALDI-TOF mass spectra appear more associated with isolate genotype, which may still have utility for future pneumococcal surveillance activities.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12866-020-02052-7.

Antimicrobial resistance in Cambodia: a review

OBJECTIVES

Following the launch of the Global Antimicrobial Resistance Surveillance System (GLASS), antimicrobial resistance (AMR) rates in many countries remain poorly described. This review provides an overview of published AMR data from Cambodia in the context of recently initiated national human and food-animal surveillance.

METHODS

PubMed and the Cochrane Database of Systematic Reviews were searched for articles published from 2000 to 2018, which reported antimicrobial susceptibility testing (AST) data for GLASS specific organisms isolated from Cambodia. Articles were screened using strict inclusion/exclusion criteria. AST data was extracted, with medians and ranges of resistance rates calculated for specific bug-drug combinations.

RESULTS

Twenty-four papers were included for final analysis, with 20 describing isolates from human populations. Escherichia coli was the most commonly described organism, with median resistance rates from human isolates of 92.8% (n=6 articles), 46.4% (n=4), 55.4% (n=8), and 46.4% (n=5) to ampicillin, 3^rd generation cephalosporins, fluoroquinolones, and gentamicin respectively.

CONCLUSIONS

Whilst resistance rates are high for several GLASS organisms, there were insufficient data to draw robust conclusions about the AMR situation in Cambodia. The recently implemented national AMR surveillance systems will begin to address this data gap.

Microorganisms Associated With Pneumonia in Children <5 Years of Age in Developing and Emerging Countries: The GABRIEL Pneumonia Multicenter, Prospective, Case-Control Study

Background

Pneumonia, the leading infectious cause of child mortality globally, mainly afflicts developing countries. This prospective observational study aimed to assess the microorganisms associated with pneumonia in children aged <5 years in developing and emerging countries.

Methods

A multicenter, case-control study by the GABRIEL (Global Approach to Biological Research, Infectious diseases and Epidemics in Low-income countries) network was conducted between 2010 and 2014 in Cambodia, China, Haiti, India (2 sites), Madagascar, Mali, Mongolia, and Paraguay. Cases were hospitalized children with radiologically confirmed pneumonia; controls were children from the same setting without any features suggestive of pneumonia. Nasopharyngeal swabs were collected from all subjects; 19 viruses and 5 bacteria were identified by reverse-transcription polymerase chain reaction. Associations between microorganisms and pneumonia were quantified by calculating the adjusted population attributable fraction (aPAF) after multivariate logistic regression analysis adjusted for sex, age, time period, other pathogens, and site.

Results

Overall, 888 cases and 870 controls were analyzed; ≥1 microorganism was detected in respiratory samples in 93.0% of cases and 74.4% of controls (P < .001). Streptococcus pneumoniae, Mycoplasma pneumoniae, human metapneumovirus, rhinovirus, respiratory syncytial virus (RSV), parainfluenza virus 1, 3, and 4, and influenza virus A and B were independently associated with pneumonia; aPAF was 42.2% (95% confidence interval [CI], 35.5%-48.2%) for S. pneumoniae, 18.2% (95% CI, 17.4%-19.0%) for RSV, and 11.2% (95% CI, 7.5%-14.7%) for rhinovirus.

Conclusions

Streptococcus pneumoniae, RSV, and rhinovirus may be the major microorganisms associated with pneumonia infections in children <5 years of age from developing and emerging countries. Increasing S. pneumoniae vaccination coverage may substantially reduce the burden of pneumonia among children in developing countries.

Comparative symbiotic plasmid analysis indicates that symbiosis gene ancestor type affects plasmid genetic evolution

Rhizobial symbiotic plasmids play vital roles in mutualistic symbiosis with legume plants by executing the functions of nodulation and nitrogen fixation. To explore the gene composition and genetic constitution of rhizobial symbiotic plasmids, comparison analyses of 24 rhizobial symbiotic plasmids derived from four rhizobial genera was carried out. Results illustrated that rhizobial symbiotic plasmids had higher proportion of functional genes participating in amino acid transport and metabolism, replication; recombination and repair; carbohydrate transport and metabolism; energy production and conversion and transcription. Mesorhizobium amorphae CCNWGS0123 symbiotic plasmid - pM0123d had similar gene composition with pR899b and pSNGR234a. All symbiotic plasmids shared 13 orthologous genes, including five nod and eight nif/fix genes which participate in the rhizobia-legume symbiosis process. These plasmids contained nod genes from four ancestors and fix genes from six ancestors. The ancestral type of pM0123d nod genes was similar with that of Rhizobium etli plasmids, while the ancestral type of pM0123d fix genes was same as that of pM7653Rb. The phylogenetic trees constructed based on nodCIJ and fixABC displayed different topological structures mainly due to nodCIJ and fixABC ancestral type discordance. The study presents valuable insights into mosaic structures and the evolution of rhizobial symbiotic plasmids.

SIGNIFICANCE AND IMPACT OF THE STUDY

This study compared 24 rhizobial symbiotic plasmids that included four genera and 11 species, illuminating the functional gene composition and symbiosis gene ancestor types of symbiotic plasmids from higher taxonomy. It provides valuable insights into mosaic structures and the evolution of symbiotic plasmids.

Burden of Influenza in Less Than 5-Year-Old Children Admitted to Hospital with Pneumonia in Developing and Emerging Countries: A Descriptive, Multicenter Study

This descriptive 4-year study reports the proportion of detection of influenza viruses in less than 5-year-old children hospitalized for pneumonia in eight developing and emerging countries and describes clinical and microbiological characteristics of influenza-related pneumonia cases. Hospitalized children presenting radiologically confirmed pneumonia aged 2-60 months were prospectively enrolled in this observational standardized study. Mean proportion of isolated influenza virus was 9.7% (95% confidence interval: 7.9-11.8%) among 888 pneumonia children analyzed, with moderate heterogeneity between countries-ranging from 6.2% in Cambodia to 18.8% in Haiti. The clinical characteristics of children with influenza-related pneumonia were not substantially different from those of other pneumonia cases. Influenza A H1N1-related pneumonia cases appeared as more severe than pneumonia cases related to other strains of influenza. Streptococcus pneumoniae was detected more often in blood samples from influenza-related cases than in those without detected influenza viruses (19.7% versus 9.5%, P = 0.018). Influenza-related pneumonia is frequent among children less than 5 years old with pneumonia, living in developing and emerging countries. Influenza might be a frequent etiologic agent responsible for pneumonia or a predisposing status factor for pneumococcal-related pneumonia in this population.

Molecular genetic diversity of Gongylonema neoplasticum (Fibiger & Ditlevsen, 1914) (Spirurida: Gongylonematidae) from rodents in Southeast Asia

More than a dozen Gongylonema spp. (Spirurida: Spiruroidea: Gongylonematidae) have been described from a variety of rodent hosts worldwide. Gongylonema neoplasticum (Fibiger & Ditlevsen, 1914), which dwells in the gastric mucosa of rats such as Rattus norvegicus (Berkenhout) and Rattus rattus (Linnaeus), is currently regarded as a cosmopolitan nematode in accordance with global dispersion of its definitive hosts beyond Asia. To facilitate the reliable specific differentiation of local rodent Gongylonema spp. from the cosmopolitan congener, the genetic characterisation of G. neoplasticum from Asian Rattus spp. in the original endemic area should be considered since the morphological identification of Gongylonema spp. is often difficult due to variations of critical phenotypical characters, e.g. spicule lengths and numbers of caudal papillae. In the present study, morphologically identified G. neoplasticum from 114 rats of seven species from Southeast Asia were selected from archived survey materials from almost 4,500 rodents: Thailand (58 rats), Cambodia (52 rats), Laos (three rats) and Philippines (one rat). In addition, several specimens from four rats in Indonesia were used in the study. Nucleotide sequences of the ribosomal RNA gene (rDNA) (5,649 bp) and the cytochrome c oxidase subunit 1 gene (cox1) (818 bp) were characterised. The rDNA showed little nucleotide variation, including the internal transcribed spacer (ITS) regions. The cox1 showed 24 haplotypes, with up to 15 (1.83%) nucleotide substitutions regardless of parasite origin. Considering that Rattus spp. have been shown to originate from the southern region of Asia and G. neoplasticum is their endogenous parasite, it is reasonable to propose that the present study covers a wide spectrum of the genetic diversity of G. neoplasticum, useful for both the molecular genetic speculation of the species and the molecular genetic differentiation of other local rodent Gongylonema spp. from the cosmopolitan congener.

Global, regional, and national disease burden estimates of acute lower respiratory infections due to respiratory syncytial virus in young children in 2015: a systematic review and modelling study

BACKGROUND

We have previously estimated that respiratory syncytial virus (RSV) was associated with 22% of all episodes of (severe) acute lower respiratory infection (ALRI) resulting in 55 000 to 199 000 deaths in children younger than 5 years in 2005. In the past 5 years, major research activity on RSV has yielded substantial new data from developing countries. With a considerably expanded dataset from a large international collaboration, we aimed to estimate the global incidence, hospital admission rate, and mortality from RSV-ALRI episodes in young children in 2015.

METHODS

We estimated the incidence and hospital admission rate of RSV-associated ALRI (RSV-ALRI) in children younger than 5 years stratified by age and World Bank income regions from a systematic review of studies published between Jan 1, 1995, and Dec 31, 2016, and unpublished data from 76 high quality population-based studies. We estimated the RSV-ALRI incidence for 132 developing countries using a risk factor-based model and 2015 population estimates. We estimated the in-hospital RSV-ALRI mortality by combining in-hospital case fatality ratios with hospital admission estimates from hospital-based (published and unpublished) studies. We also estimated overall RSV-ALRI mortality by identifying studies reporting monthly data for ALRI mortality in the community and RSV activity.

FINDINGS

We estimated that globally in 2015, 33·1 million (uncertainty range [UR] 21·6-50·3) episodes of RSV-ALRI, resulted in about 3·2 million (2·7-3·8) hospital admissions, and 59 600 (48 000-74 500) in-hospital deaths in children younger than 5 years. In children younger than 6 months, 1·4 million (UR 1·2-1·7) hospital admissions, and 27 300 (UR 20 700-36 200) in-hospital deaths were due to RSV-ALRI. We also estimated that the overall RSV-ALRI mortality could be as high as 118 200 (UR 94 600-149 400). Incidence and mortality varied substantially from year to year in any given population.

INTERPRETATION

Globally, RSV is a common cause of childhood ALRI and a major cause of hospital admissions in young children, resulting in a substantial burden on health-care services. About 45% of hospital admissions and in-hospital deaths due to RSV-ALRI occur in children younger than 6 months. An effective maternal RSV vaccine or monoclonal antibody could have a substantial effect on disease burden in this age group.

FUNDING

The Bill & Melinda Gates Foundation.

The Relevance of a Novel Quantitative Assay to Detect up to 40 Major Streptococcus pneumoniae Serotypes Directly in Clinical Nasopharyngeal and Blood Specimens

For epidemiological and surveillance purposes, it is relevant to monitor the distribution and dynamics of Streptococcus pneumoniae serotypes. Conventional serotyping methods do not provide rapid or quantitative information on serotype loads. Quantitative serotyping may enable prediction of the invasiveness of a specific serotype compared to other serotypes carried. Here, we describe a novel, rapid multiplex real-time PCR assay for identification and quantification of the 40 most prevalent pneumococcal serotypes and the assay impacts in pneumonia specimens from emerging and developing countries. Eleven multiplex PCR to detect 40 serotypes or serogroups were optimized. Quantification was enabled by reference to standard dilutions of known bacterial load. Performance of the assay was evaluated to specifically type and quantify S. pneumoniae in nasopharyngeal and blood samples from adult and pediatric patients hospitalized with pneumonia (n = 664) from five different countries. Serogroup 6 was widely represented in nasopharyngeal specimens from all five cohorts. The most frequent serotypes in the French, South African, and Brazilian cohorts were 1 and 7A/F, 3 and 19F, and 14, respectively. When both samples were available, the serotype in blood was always present as carriage with other serotypes in the nasopharynx. Moreover, the ability of a serotype to invade the bloodstream may be linked to its nasopharyngeal load. The mean nasopharyngeal concentration of the serotypes that moved to the blood was 3 log-fold higher than the ones only found in the nasopharynx. This novel, rapid, quantitative assay may potentially predict some of the S. pneumoniae serotypes invasiveness and assessment of pneumococcal serotype distribution.

Biodiversity and health: Lessons and recommendations from an interdisciplinary conference to advise Southeast Asian research, society and policy

Southeast Asia is an economic, biodiverse, cultural and disease hotspot. Due to rapid socio-economic and environmental changes, the role of biodiversity and ecosystems for human health ought to be examined and communicated to decision-makers and the public. We therefore summarized the lessons and recommendations from an interdisciplinary conference convened in Cambodia in 2014 to advise Southeast Asian societies on current research efforts, future research needs, and to provide suggestions for improved education, training and science-policy interactions. First, we reviewed several examples of the important role of ecosystems as 'sentinels' in the sense that potentially harmful developments for human health become first apparent in ecosystem components. Other ecosystem services which also benefit human well-being are briefly summarized. Second, we summarized the recommendations of the conference's roundtable discussions and added recent developments in the science-policy interface. The recommendations were organized along five themes: Ethical and legal considerations; implementation of the One Health approach; education, training, and capacity building; future research priorities; and potential science-policy interactions. While the role of biodiversity for human health needs further research, especially for zoonoses and emerging diseases, many direct and indirect benefits to human health are already apparent, but have yet to filter down to the science-policy interface in order to influence legislation and enforcement. Therefore, efforts to strengthen the interface in Southeast Asia should become a high priority in order to strengthen the health and resilience of Southeast Asian societies.

Multicenter case-control study protocol of pneumonia etiology in children: Global Approach to Biological Research, Infectious diseases and Epidemics in Low-income countries (GABRIEL network)

BACKGROUND

Data on the etiologies of pneumonia among children are inadequate, especially in developing countries. The principal objective is to undertake a multicenter incident case-control study of <5-year-old children hospitalized with pneumonia in developing and emerging countries, aiming to identify the causative agents involved in pneumonia while assessing individual and microbial factors associated with the risk of severe pneumonia.

METHODS/DESIGN

A multicenter case-control study, based on the GABRIEL network, is ongoing. Ten study sites are located in 9 countries over 3 continents: Brazil, Cambodia, China, Haiti, India, Madagascar, Mali, Mongolia, and Paraguay. At least 1,000 incident cases and 1,000 controls will be enrolled and matched for age and date. Cases are hospitalized children <5 years with radiologically confirmed pneumonia, and the controls are children without any features suggestive of pneumonia. Respiratory specimens are collected from all enrolled subjects to identify 19 viruses and 5 bacteria. Whole blood from pneumonia cases is being tested for 3 major bacteria. S. pneumoniae-positive specimens are serotyped. Urine samples from cases only are tested for detection of antimicrobial activity. The association between procalcitonin, C-reactive protein and pathogens is being evaluated. A discovery platform will enable pathogen identification in undiagnosed samples.

DISCUSSION

This multicenter study will provide descriptive results for better understanding of pathogens responsible for pneumonia among children in developing countries. The identification of determinants related to microorganisms associated with pneumonia and its severity should facilitate treatment and prevention.

Plasma concentrations, efficacy and safety of efavirenz in HIV-infected adults treated for tuberculosis in Cambodia (ANRS 1295-CIPRA KH001 CAMELIA trial)

OBJECTIVE

To assess efavirenz plasma concentrations and their association with treatment efficacy and tolerance of efavirenz 600 mg daily in HIV-tuberculosis co-infected patients.

METHODS

HIV-infected adults with CD4+ T cell count ≤ 200/mm(3) received standard 6-month tuberculosis treatment and antiretroviral therapy including a daily-dose of 600 mg of efavirenz, irrespective of their body weight. Mid-dose blood samples were drawn both on tuberculosis treatment (week +2 and week +6 after antiretroviral therapy initiation, and week 22 of follow-up) and off tuberculosis treatment (week 50 of follow-up). Considered therapeutic range was 1,000 to 4,000 ng/mL. Multivariate analysis was performed to evaluate the association between efavirenz concentration below 1,000 ng/mL and virological failure. Linear regression was used to test the association between efavirenz exposure and CD4+ T cell gain. Severe side effects potentially related to efavirenz were described and their association with efavirenz exposure was tested by multivariate analysis.

RESULTS

Efavirenz plasma concentrations were available in 540 patients. Median [interquartile range] efavirenz concentrations were 2,674 ng/mL [1,690-4,533], 2,667 ng/mL [1,753-4,494] and 2,799 ng/mL [1,804-4,744] at week +2, week +6, week 22, respectively, and 2,766 ng/mL [1,941-3,976] at week 50. Efavirenz concentrations were lower at week 50 (off rifampicin) compared to week 22 (on rifampicin) (p<0.001). Late attendance to study visit and low hemoglobinemia were the only factors associated with an increased risk of efavirenz concentration below 1,000 ng/mL. Efavirenz concentration below 1,000 ng/mL was not associated with treatment failure. Efavirenz concentration above 4,000 ng/mL was associated with higher risk of central nervous system side effects (p<0.001) and of hepatotoxicity (p<0.001).

CONCLUSION

Body weight and tuberculosis treatment were not associated with low efavirenz concentrations or treatment failure, supporting the 600 mg daily-dose of efavirenz in HIV-tuberculosis co-infected patients. High efavirenz concentrations were related to a higher risk of central nervous system side effects and hepatotoxicity.

TRIAL REGISTRATION

ClinicalTrials.gov NCT01300481.

Plasma concentrations of efavirenz with a 600 mg standard dose in Cambodian HIV-infected adults treated for tuberculosis with a body weight above 50 kg

BACKGROUND

The optimal dose of efavirenz for HIV-infected patients receiving a tuberculosis regimen including rifampicin remains debated, especially for subjects weighing over 50 kg. To address this issue, we measured plasma efavirenz concentrations from Cambodian adults with tuberculosis enrolled in the CAMELIA randomized trial (ClinicalTrials.gov number, NCT01300481) 6 weeks after the onset of antiretroviral therapy.

METHODS

Efavirenz concentrations and proportions of patients with concentrations below 1,000 ng/ml were compared across patient body weight below or above 50 kg using a Student's t-test and a χ(2) test, respectively. Factors associated with efavirenz concentrations below 1,000 ng/ml were identified by logistic regression analysis. Logistic regression analysis was also performed to check if efavirenz concentrations below 1,000 ng/ml were associated with virological failure.

RESULTS

Plasma efavirenz concentrations were higher in the 332 patients who weighed <50 kg compared with the 150 who weighed ≥50 kg (median [IQR] 2,859 [1,787-4,749] and 2,060 [1,425-3,575] ng/ml, respectively; P=0.02). However, the proportion of patients with efavirenz concentrations below 1,000 ng/ml was not different between those weighing less than or more than 50 kg (6% and 10%, respectively; P=0.13) and a body weight above 50 kg was not associated with a higher risk of plasma efavirenz concentrations below 1,000 ng/ml. When plasma efavirenz concentrations below 1,000 ng/ml were present, they were not associated with virological failure.

CONCLUSIONS

The current WHO guidelines recommending 600 mg efavirenz daily irrespective of patient's body weight remains a safe and effective approach to treating coinfected adults needing simultaneous tuberculosis and HIV therapy.

Performance of "VIKIA Malaria Ag Pf/Pan" (IMACCESS®), a new malaria rapid diagnostic test for detection of symptomatic malaria infections

Background

Recently, IMACCESS® developed a new malaria test (VIKIA Malaria Ag Pf/Pan™), based on the detection of falciparum malaria (HRP-2) and non-falciparum malaria (aldolase).

Methods

The performance of this new malaria rapid diagnostic test (RDT) was assessed using 1,000 febrile patients seeking malaria treatment in four health centres in Cambodia from August to December 2011. The results of the VIKIA Malaria Ag Pf/Pan were compared with those obtained by microscopy, the CareStart Malaria™ RDT (AccessBio®) which is currently used in Cambodia, and real-time PCR (as “gold standard”).

Results

The best performances of the VIKIA Malaria Ag Pf/Pan™ test for detection of both Plasmodium falciparum and non-P. falciparum were with 20–30 min reading times (sensitivity of 93.4% for P. falciparum and 82.8% for non-P. falciparum and specificity of 98.6% for P. falciparum and 98.9% for non-P. falciparum) and were similar to those for the CareStart Malaria™ test.

Conclusions

This new RDT performs similarly well as other commercially available tests (especially the CareStart Malaria™ test, used as comparator), and conforms to the World Health Organization’s recommendations for RDT performance. It is a good alternative tool for the diagnosis of malaria in endemic areas.

A one-year study to assess the safety and efficacy of the CB1R inverse agonist taranabant in overweight and obese patients with type 2 diabetes

AIM

To evaluate the efficacy and safety of taranabant in overweight and obese patients with type 2 diabetes mellitus (T2DM).

METHODS

This was a multicenter, double-blind, randomized, placebo-controlled study in overweight and obese patients with T2DM (ages > or = 18 and < or = 75 years) with a BMI > or = 27 kg/m(2) and < or = 43 kg/m(2) and HbA1c > or =7.0 and < or = 10.0%, who were either not on an antihyperglycaemic agent or on a stable dose of metformin (> or = 1500 mg/day). After a 2-week placebo run-in, patients were randomized to placebo (N = 156) or taranabant 0.5-mg (N = 155), 1-mg (N = 157), or 2-mg (N = 155) once daily for 52 weeks. Primary efficacy endpoints were changes from baseline in body weight (BW) and HbA1c at Week 36, with results at Week 52 being key secondary endpoints.

RESULTS

In the all-patients-treated population, using a last-observation-carried-forward analysis, reductions in BW were -2.5, -3.7, -4.5 and -5.1 kg at Week 36 and -2.4, -4.0, -4.6 and -5.3 kg at Week 52 in the placebo, 0.5-, 1- and 2-mg groups, respectively (all doses significant vs. placebo at both time points). The proportion of patients who lost > or = 5 and > or = 10% of their baseline BW was significantly greater in the 1- and 2-mg groups vs. placebo at Week 36 and all taranabant groups vs. placebo at Week 52. Reductions in HbA1c were -0.40, -0.47, -0.68 and -0.71% at Week 36 and -0.30, -0.43, -0.65 and -0.64% at Week 52, in the placebo, 0.5-, 1- and 2-mg groups, respectively (1- and 2-mg doses significant vs. placebo at both time points). After 52 weeks, the incidences of adverse experiences classified in the gastrointestinal (diarrhoea, nausea, vomiting), nervous system-related (dizziness, sensory-related), and psychiatric (irritability, depression-related) organ systems were numerically higher or statistically significantly higher in all taranabant groups compared with the placebo group.

CONCLUSIONS

After 36 and 52 weeks, treatment with taranabant at the 1- and 2-mg doses led to clinically significant weight loss and improvement in glycaemic parameters in overweight and obese patients with T2DM that was associated with dose-related increases in adverse experiences. Based on these data and data from other Phase III clinical studies, it was determined that the overall safety and efficacy profile of taranabant did not support further development for the treatment of obesity.

Sub-microscopic malaria cases and mixed malaria infection in a remote area of high malaria endemicity in Rattanakiri province, Cambodia: implication for malaria elimination

BACKGROUND

Malaria microscopy and rapid diagnostic tests are insensitive for very low-density parasitaemia. This insensitivity may lead to missed asymptomatic sub-microscopic parasitaemia, a potential reservoir for infection. Similarly, mixed infections and interactions between Plasmodium species may be missed. The objectives were first to develop a rapid and sensitive PCR-based diagnostic method to detect low parasitaemia and mixed infections, and then to investigate the epidemiological importance of sub-microscopic and mixed infections in Rattanakiri Province, Cambodia.

METHODS

A new malaria diagnostic method, using restriction fragment length polymorphism analysis of the cytochrome b genes of the four human Plasmodium species and denaturing high performance liquid chromatography, has been developed. The results of this RFLP-dHPLC method have been compared to 1) traditional nested PCR amplification of the 18S rRNA gene, 2) sequencing of the amplified fragments of the cytochrome b gene and 3) microscopy. Blood spots on filter paper and Giemsa-stained blood thick smears collected in 2001 from 1,356 inhabitants of eight villages of Rattanakiri Province have been analysed by the RFLP-dHPLC method and microscopy to assess the prevalence of sub-microscopic and mixed infections.

RESULTS

The sensitivity and specificity of the new RFLP-dHPLC was similar to that of the other molecular methods. The RFLP-dHPLC method was more sensitive and specific than microscopy, particularly for detecting low-level parasitaemia and mixed infections. In Rattanakiri Province, the prevalences of Plasmodium falciparum and Plasmodium vivax were approximately two-fold and three-fold higher, respectively, by RFLP-dHPLC (59% and 15%, respectively) than by microscopy (28% and 5%, respectively). In addition, Plasmodium ovale and Plasmodium malariae were never detected by microscopy, while they were detected by RFLP-dHPLC, in 11.2% and 1.3% of the blood samples, respectively. Moreover, the proportion of mixed infections detected by RFLP-dHPLC was higher (23%) than with microscopy (8%).

CONCLUSIONS

The rapid and sensitive molecular diagnosis method developed here could be considered for mass screening and ACT treatment of inhabitants of low-endemicity areas of Southeast Asia.

Exercise primes a molecular memory for brain-derived neurotrophic factor protein induction in the rat hippocampus

Exercise is an important facet of behavior that enhances brain health and function. Increased expression of the plasticity molecule brain-derived neurotrophic factor (BDNF) as a response to exercise may be a central factor in exercise-derived benefits to brain function. In rodents, daily wheel-running exercise increases BDNF gene and protein levels in the hippocampus. However, in humans, exercise patterns are generally less rigorous, and rarely follow a daily consistency. The benefit to the brain of intermittent exercise is unknown, and the duration that exercise benefits endure after exercise has ended is unexplored. In this study, BDNF protein expression was used as an index of the hippocampal response to exercise. Both daily exercise and alternating days of exercise increased BDNF protein, and levels progressively increased with longer running duration, even after 3 months of daily exercise. Exercise on alternating days was as effective as daily exercise, even though exercise took place only on half as many days as in the daily regimen. In addition, BDNF protein remained elevated for several days after exercise ceased. Further, after prior exercise experience, a brief second exercise re-exposure insufficient to cause a BDNF change in naïve animals, rapidly reinduced BDNF protein to levels normally requiring several weeks of exercise for induction. The protein reinduction occurred with an intervening "rest" period as long as 2 weeks. The rapid reinduction of BDNF by an exercise stimulation protocol that is normally subthreshold in naïve animals suggests that exercise primes a molecular memory for BDNF induction. These findings are clinically important because they provide guidelines for optimizing the design of exercise and rehabilitation programs, in order to promote hippocampal function.

Enhanced expression of renal endothelin-converting enzyme-1 and endothelin-A-receptor mRNA in rats with interstitial fibrosis following ureter ligation

Endothelin-1 (ET-1) has been implicated in many chronic renal glomerular diseases. The purpose of this study was to investigate whether the levels of mRNA expression of endothelin-converting enzyme-1 (ECE-1) and endothelin-A- and -B- (ET(A) and ET(B)) receptors are altered during the progression of interstitial fibrosis following ureter ligation. Rats were subjected to left ureter ligation or a sham operation and euthanized 5 days afterward. Kidneys were fixed in Carnoy's fixative, embedded in paraffin, and sectioned for assessment of interstitial fibrosis by staining for collagen III using immunofluorescence techniques. The area occupied by collagen staining was quantified by image analysis. Kidneys from obstructed rats showed a 54% increase in the area occupied by collagen III staining compared to the contralateral kidney, and an 89% increase compared to sham-operated kidneys. The mRNA levels of ECE-1, as well as ET(A)- and ET(B)-receptors in the kidney were analyzed by Northern blots. It was found that the ECE-1 and ET(A)-receptor mRNA levels in kidneys subjected to ureter ligation increased by 92% and 71%, respectively, when compared with those obtained from the contralateral kidneys. In contrast, mRNA levels of ET(B)-receptors were not significantly different between the two groups. These results suggest that ET-1, through interaction with the ET(A)-receptors, may play a role in the progression of interstitial fibrosis following ureter ligation.

Attenuation of puromycin aminonucleoside-induced glomerular lesions in rats by CGS 26303, a dual neutral endopeptidase/endothelin-converting enzyme inhibitor

Endothelin-1 (ET-1) has been implicated in the pathogenesis of various renal diseases. The purpose of this study was to investigate the effect of CGS 26303, an endothelin-converting enzyme (ECE) inhibitor, on puromycin aminonucleoside (PA)-induced nephrosis in rats. The animals (three groups; n = 8 per group) received 50 mg/kg PA or NaCl, intravenously. CGS 26303 (5 mg/kg/day, s.c. via osmotic minipumps) or vehicle was administered to the PA-treated animals for 4 weeks, starting within 5 min after PA injection. Uninephrectomy was performed 2 weeks after PA to accelerate the renal damage. Rats received no treatment between 4 and 8 weeks. At 8 weeks rats were euthanized and kidneys removed for histology and analysis for mRNA levels of endothelin-A- and -B- (ET(A) and ET(B)) receptors and ECE-1. Glomeruli (100 glomeruli/section; 800/group) were graded as normal (N), mild lesion (ML = few periodic acid-Schiff positive [PAS+] droplets and small adhesions to Bowman's capsule), and moderate to severe lesion (SL = many PAS+ droplets, adhesions to and thickening of Bowman's capsule, mesangial expansion, and cystic dilations of glomerular capillaries). In the PA + vehicle group N, ML and SL were 39.5%, 11.9% and 48.6%, respectively, while the respective values were 68.3%, 9.4%, and 22.3% in PA + CGS 26303-treated rats. However, the renal mRNA levels of ECE-1 and ET(A)- and ET(B)-receptors were not significantly different among the three groups. These results confirm the efficacy of ECE inhibition in this disease model. On the other hand, the mRNA data suggest that either there was no change in the expression of the genes examined or their levels had already returned to normal by the end of the experiment.

Design and synthesis of a potent and selective endothelin-converting enzyme inhibitor, CGS 35066

CGS 26303 has previously been shown to inhibit human endothelin converting enzyme-1 (ECE-1) with an IC50 of 410 nM and to be efficacious in several animal disease models. However, it is a more potent inhibitor of neutral endopeptidase 24.11 (NEP) with an IC50 of 1 nM. The aim of this study was to optimize CGS 26303 for greater potency and selectivity towards ECE-1 inhibition. The in vivo activity of the compounds was assessed by inhibition of the big endothelin-1 (ET-1)-induced pressor response in anesthetized rats at 90 min after treatment with a dose of 10 mg/kg, i.v. Under these conditions, CGS 26303 inhibited the pressor response to big ET-1 by 50%. Replacement of the biphenyl and tetrazol groups in CGS 26303 with a dibenzofuran and carboxylic acid, respectively, yielded CGS 35066, a potent ECE-1 inhibitor having an IC50 of 22 nM. In contrast, these substitutions markedly weakened the NEP inhibitory activity of the compound to an IC50 of 2.3 microM. CGS 35066 also exhibited a potent and sustained ECE-1 inhibitory activity in vivo, blocking the pressor response to big ET-1 by 84%. Its orally active prodrug, CGS 35339, was obtained by introducing two phenyl groups at the phosphonic acid substituent in CGS 35066. Therefore, CGS 35066 and CGS 35339 represent novel compounds for assessing the pathogenic role of ET-1 overproduction in various disease states.

CGS 34043: a non-peptidic, potent and long-acting dual inhibitor of endothelin converting enzyme-1 and neutral endopeptidase 24.11

Endothelin-1 (ET- 1) is a potent vasoconstrictor. Its biosynthesis is catalyzed by endothelin converting enzyme (ECE). In contrast, atrial natriuretic peptide (ANP) is a potent vasorelaxant and diuretic, and it is mainly degraded by neutral endopeptidase 24.11 (NEP). Therefore, compounds that can suppress the production of ET-1 by inhibiting ECE while simultaneously potentiating the levels of ANP by inhibiting NEP may be novel agents for the treatment of cardiovascular and renal dysfunction. CGS 34043 is one such compound, which inhibited the activities of ECE-1a and NEP with IC50 values of 5.8 and 110 nM, respectively. In vivo, it inhibited the pressor response induced by big ET-1, the precursor of ET-1, dose-dependently in rats, and the inhibition was sustained for at least 2 hr. In addition, CGS 34043 increased plasma ANP by 150% up to 4 hr after an intravenous dose of 10 mg/kg in conscious rats infused with ANP. However, this compound had no effect on the angiotensin I-induced pressor response. These results demonstrate that CGS 34043 is a potent and long-lasting dual inhibitor of ECE-1 and NEP. Consequently, it may be beneficial for the treatment of diseases in which an overproduction of ET-1 and/or enhanced degradation of ANP plays a pathogenic role. The activity of CGS 34753, an orally active prodrug of CGS 34043, is also described.

Potent and selective non-peptidic inhibitors of endothelin-converting enzyme-1 with sustained duration of action

Potent and selective non-peptidic inhibitors of human endothelin-converting enzyme-1 (ECE-1) have been designed as potential modulators of endothelin (ET-1) production in vivo. Because of its unique structural characteristics and long duration of action in vivo, the dual ECE-1 and neutral endopeptidase 24.11 (NEP) inhibitor, CGS 26303, was selected as an attractive lead for further optimization of potency and selectivity. Replacement of the P(1)' biphenyl substituent of CGS 26303 by a conformationally restricted 3-dibenzofuranyl group led to more potent and more selective ECE-1 inhibitors, such as the tetrazole 27. The remarkable effect of this P(1)' modification allowed for the first time phosphonomethylcarboxylic acids, such as 29, to display both potent (IC(50) = 22 nM) and selective (104-fold vs NEP) ECE-1 inhibition. Chemoenzymatic syntheses of the new alpha-amino acid (S)-3-dibenzofuran-3-ylalanine intermediate were developed, and improved procedures to generate substituted alpha-aminoalkylphosphonic acids were devised to support the production of various analogues. Although additional gains in intrinsic ECE-1 inhibitory potency could occasionally be achieved by addition of a P(1) side chain, these compounds (e.g. 43a) showed poor functional activity in vivo in the big ET-1 pressor test. Phosphonoalkyl dipeptides featuring 3-dibenzofuranyl groups in both the P(1)' and P(2)' positions were also very potent ECE-1 inhibitors, albeit lacking the desired selectivity against NEP. Functionally, 27and 29 were the two most efficacious compounds from this study, producing sustained inhibition of ECE-1 activity in rats, as measured by their ability to block the hypertensive effects induced by big ET-1. This profile was similar to that of a potent ET(A)/ET(B) dual receptor antagonist, SB 209670. Due to their favorable in vitro and in vivo profiles, 27 (CGS 34043) and 29 (CGS 35066) constitute new pharmacological tools useful in assessing the role of ECE-1 in pathological conditions.

Use of bioluminescent aequorin for the pharmacological characterization of 5HT receptors

A convenient functional assay for 5HT2a and 5HT2c receptors is reported utilizing the bioluminescent aequorin to detect intracellular calcium changes. Using this assay, the pharmacological properties of many 5HT ligands can be determined in a 96-well format. The data indicate that the aequorin detection method is superior to the inositol phosphate assay with regard to speed and scope. This system is also appropriate for kinetic studies of receptor desensitization. We showed that the human 5HT2c receptor desensitizes in a biphasic manner, with a fast desensitization of approximately 90% of the total response occurring within 15 minutes while the remaining 10% response remains for at least 3 hours.

Feasibility of bioremediation of trichloroethylene contaminated sites by nitrifying bacteria through cometabolism with ammonia

The autotrophic ammonia-oxidizing bacteria (Nitrosomonas sp.) are able to dechlorinate trichloroethylene (TCE) through cometabolism using ammonia (NH(3)) as a growth substrate. Cometabolic kinetics models suggest that TCE is a potent competitive inhibitor of NH(3) oxidation because it competes with NH(3) for oxidation by the enzyme of ammonia monooxygenase (AMO). In this study, an enriched culture of nitrifying bacteria was used to investigate the efficiencies of cometabolism of TCE by AMO. In addition, the relationships among specific growth substrate (NH(3)) utilization rate (qNH(3)), specific nongrowth substrate (TCE) cometabolic rate (qTCE), NH(3) and TCE concentrations, and NH(3)/TCE and TCE/NH(3) ratios were also analyzed. We found that the relationships between qNH(3) and NH(3) for the systems with and without TCE followed the Alvarez-Cohen competitive inhibition model and Monod model, respectively. Our results demonstrate that TCE could be cometabolized in a nitrification system when sufficient oxygen and NH(3)200 microg/l) were also found to show inhibitory effects towards NH(3) oxidation in enriched nitrifying culture. We also found that the NH(3)/TCE ratio rather than TCE concentrations alone exhibited strong correlation with qNH(3), much the same as the Ely activity recovery model presented. Our results suggest that the relationship between qTCE and TCE concentrations followed the Oldenhuis enzyme inactivation model for systems without NH(3).

Effect of matrix metalloproteinase inhibition on progression of atherosclerosis and aneurysm in LDL receptor-deficient mice overexpressing MMP-3, MMP-12, and MMP-13 and on restenosis in rats after balloon injury

The broad-spectrum MMP inhibitor CGS 27023A was tested to determine its potential as a therapy for atherosclerosis, aneurysm, and restenosis. LDL receptor-deficient (LDLr -/-) mice fed a high-fat, cholic acid-enriched diet for 16 weeks developed advanced aortic atherosclerosis with destruction of elastic lamina and ectasia in the media underlying complex plaques. Lesion formation correlated with a 4.6- to 21.7-fold increase in MMP-3, -12, and -13 expression. Treatment with CGS 27023A (p.o., b.i.d. at 50 mg/kg) had no effect on the extent of aortic atherosclerosis (36 +/- 4% versus 30 +/- 2% in controls), but both aortic medial elastin destruction and ectasia grade were significantly reduced (38% and 36%, respectively, p < 0.05). In the rat ballooned-carotid-artery model, CGS 27023A (12.5 mg/kg/day via osmotic minipump) reduced smooth muscle cell migration at 4 days by 83% (p < 0.001). Intimal lesions were reduced by 85% at 7 days (p < 0.001), but intimal smooth muscle proliferation was unaffected, and inhibitory efficacy was lost with time. At 12 days, intimal lesion reduction was less potent (52%, p < 0.01). At 3 and 6 weeks, reductions of 11% and 4%, respectively, were not significant. This demonstrates that it is essential to include late time points when the ballooned-carotid-artery model is employed to ensure that lesion size does not "catch up" when a compound solely inhibits smooth muscle cell migration. In summary, MMP inhibitor therapy delayed but did not prevent intimal lesions, thereby demonstrating little promise to prevent restenosis. In contrast, MMP inhibitor therapy may prove useful to retard progression of aneurysm.

NH4+ transport system of a psychrophilic marine bacterium, Vibrio sp. strain ABE-1

NH4(+) transport system of a psychrophilic marine bacterium Vibrio sp. strain ABE-1 (Vibrio ABE-1) was examined by measuring the uptake of [14C]methylammonium ion (14CH3NH3+) into the intact cells. 14CH3NH3+ uptake was detected in cells grown in medium containing glutamate as the sole nitrogen source, but not in those grown in medium containing NH4Cl instead of glutamate. Vibrio ABE-1 did not utilize CH3NH3+ as a carbon or nitrogen source. NH4Cl and nonradiolabeled CH3NH3+ completely inhibited 14CH3NH3+ uptake. These results indicate that 14CH3NH3+ uptake in this bacterium is mediated via an NH4+ transport system and not by a specific carrier for CH3NH3+. The respiratory substrate succinate was required to drive 14CH3NH3+ uptake and the uptake was completely inhibited by KCN, indicating that the uptake was energy dependent. The electrochemical potentials of H+ and/or Na+ across membranes were suggested to be the driving forces for the transport system because the ionophores carbonylcyanide m-chlorophenylhydrazone and monensin strongly inhibited uptake activities at pH 6.5 and 8.5, respectively. Furthermore, KCl activated 14CH3NH3+ uptake. The 14CH3NH3+ uptake activity of Vibrio ABE-1 was markedly high at temperatures between 0 degrees and 15 degrees C, and the apparent Km value for CH3NH3+ of the uptake did not change significantly over the temperature range from 0 degrees to 25 degrees C. Thus, the NH4+ transport system of this bacterium was highly active at low temperatures.

MEC-12, an alpha-tubulin required for touch sensitivity in C. elegans

mec-12 is one of a dozen genes required for touch receptor neuron function in Caenorhabditis elegans. Some mec-12 mutants (mechanosensory-defective) lack the large-diameter microtubules that are characteristic of these neurons (15 protofilaments, as opposed to 11). Mutants of mec-7, a alpha-tubulin encoding gene, have a similar phenotype. We have identified the nature of mec-12 by germline transformation rescue and characterization of a point mutation. Sequence analysis of the mec-12 encoded product (MEC-12) indicates that it corresponds to a novel C. elegans alpha-tubulin. MEC-12 is the only identified C. elegans alpha-tubulin that contains a lysine at position 40, a known site of post-translational acetylation. Some mec-12 mutations eliminate microtubule acetylation as assayed immunocyto-chemically; phenotypic rescue using a MEC-12 variant lacking the lysine-40 showed that acetylation is not required for MEC-12 activity. Although functionally needed only in the touch neurons, mec-12 is expressed in several other neuron types. These results support the notion that tubulin isotype diversity contributes to the formation of distinct classes of microtubules; 15-protofilament microtubule assembly requires MEC-12 alpha-tubulin and MEC-7 beta-tubulin, which are both highly expressed in the touch receptor neurons. MEC-12 is the first reported alpha-tubulin isotype that appears to be required in a single class of neuronal microtubules.

Temporal patterns of DNA adduct formation and glutathione S-transferase activity in the testes of rats fed aflatoxin B1: a comparison with patterns in the liver

Fisher-344 male rats were fed 1.6 ppm of aflatoxin B1 (AFB1) continuously and intermittently for several weeks. At various time periods, DNA was isolated from the testes and livers and analyzed for AFB1-DNA adducts. The ability of the testis to detoxify AFB1 was also investigated by the glutathione S-transferase (GST) activity assay and compared with that of the liver. The levels of testicular AFB1-DNA adducts were 2.4 to 8.1 times lower than those of the liver after 4 to 16 weeks of continuous treatment and 2.2 to 46.2 times lower after 8 to 20 weeks of intermittent treatment. The testicular DNA adducts markedly decreased over time. By 16 weeks of continuous and 20 weeks of intermittent exposure, they had decreased 37 and 91%, respectively. In contrast, hepatic AFB1-DNA adducts increased four-fold from 4 to 16 weeks of continuous treatment but increased at a much slower rate after intermittent exposure. In both the liver and testis, significant levels of AFB1-DNA adducts persisted for at least 1 month after ending the treatment, suggesting that this type of lesion was poorly repaired. In control rats, the testis showed significantly higher GST activity than the liver. In treated rats, these differences were significant during the first 12 weeks of continuous treatment but not at later times. Tissue-specific differences such as germ-cell depletion and increased testicular detoxification may play an important role in the observed differential pattern of DNA adduct formation between the testis and liver.

Production of leptin in Escherichia coli: a comparison of methods

A procedure is described for gram-scale refolding of Escherichia coli-derived human leptin inclusion bodies. Refolding was achieved by gradually reducing denaturant using a diafiltration method. Refolded leptin is characterized by in vivo modulation of food intake, reduction in body weight, and lowering of insulin and glucose levels in ob/ob mice. In addition, refolded leptin is characterized by radioimmunoassay (RIA) and activation of the leptin receptor in a cell-based assay. For comparison we also refolded leptin by a simple dilution method and produced periplasmic derived leptin, which did not require ex vivo folding. Leptin produced by these three methods and leptin obtained from commercial sources were compared using the RIA and the cell-based assay and appeared to be of comparable quality and potency.

Design and synthesis of potent, selective inhibitors of endothelin-converting enzyme

Endothelin-1 is the most potent peptidic vasoconstrictor discovered to date. The final step of posttranslational processing of this peptide is the conversion of its precursor by endothelin-converting enzyme-1 (ECE-1), a metalloprotease which displays high amino acid sequence identity with neutral endopeptidase 24.11 (NEP) especially at the catalytic center. A series of potent and selective arylacetylene-containing ECE-1 inhibitors have been prepared. (S, S)-3-Cyclohexyl-2-[[5-(2, 4-difluorophenyl)-2-[(phosphonomethyl)amino]pent-4-ynoyl]amino] propio nic acid (47), an arylacetylene amino phosphonate dipeptide, was found to inhibit ECE-1 and NEP with IC50 values of 14 nM and 2 microM, respectively. Similarly, (S)-[[1-[(2-biphenyl-4-ylethyl)carbamoyl]-4-(2-fluorophenyl)but-3- yny l]amino]methyl]phosphonic acid (56), an arylacetylene amino phosphonate amide, had IC50's of 33 nM and 6.5 microM for ECE-1 and NEP, respectively. Slight modification of the aryl moiety was found to have dramatic effects on ECE-1/NEP selectivity. The 2-fluoro dipeptide analogue, (S, S)-2-[[5-(2-fluorophenyl)-2-[(phosphonomethyl)amino]pent-4-ynoyl]+ ++amin o]-4-methylpentanoic acid (40), showed a 72-fold selectivity for ECE-1 over NEP, while the 3-fluoro dipeptide analogue, (S, S)-2-[[5-(3-fluorophenyl)-2-[(phosphonomethyl)amino]pent-4-ynoyl]+ ++amin o]-4-methylpentanoic acid (22), was equipotent for ECE-1 and NEP. Several of these inhibitors were shown to be potent in blocking ET-1 production in vivo as demonstrated by the big ET-1-induced pressor response in rats. These potent inhibitors are the most selective for ECE-1 reported to date and are envisaged to have a variety of therapeutic applications.

Sulfonamide-based hydroxamic acids as potent inhibitors of mouse macrophage metalloelastase

The structural requirements of sulfonamide-based hydroxamic acid 1 for inhibition of macrophage metalloelastase (MME) were investigated. A short aliphatic group at the R2 position together with an aromatic group at the R3 position significantly improved the inhibitory activity. Compounds 32, 34, and 40 were the most potent inhibitors of MME with IC50 values between 5 and 6 nM.

Suppression of substance P biosynthesis in sensory neurons of dorsal root ganglion by prodrug esters of potent peptidylglycine alpha-amidating monooxygenase inhibitors

Substance P as well as many other neuropeptides are synthesized as glycine-extended precursors and converted to the biologically active C-terminal amides by posttranslational modification. The final step of posttranslational processing is catalyzed by peptidylglycine alpha-amidating monooxygenase (PAM). In a previous study, N-substituted homocysteine analogs were found to be potent inhibitors of PAM partially purified from conditioned medium of cultured rat medullary thyroid carcinoma CA-77 cells. These compounds, however, were only modest inhibitors of substance P production in cultured dorsal root ganglion cells, possibly because of poor cell penetration. Several ester derivatives of hydrocinnamoyl-phenylalanyl-homocysteine, one of the most potent PAM inhibitors, were prepared to increase the intracellular accessibility of these compounds. Hydrocinnamoyl-phenylalanyl-(S-benzoyl-homocysteine) benzyl ester was identified as the most potent compound, inhibiting substance P biosynthesis in dorsal root ganglion cells with an IC50 of 2 microM. Inhibition of PAM resulted in a concomitant increase in the glycine-extended substance p (substance P-Gly) precursor peptide. In the presence of 3 microM benzyl ester derivative, the intracellular substance P-Gly level was 2.4-fold higher while the substance P level was 2.1-fold lower than the corresponding peptides in control cells. These results suggest that PAM inhibition represents an effective method for suppression of substance P biosynthesis and, therefore, may have therapeutic utility in conditions associated with elevated substance P levels. Furthermore, PAM inhibition may also prove useful in decreasing other amidated peptides.