The impact of food type, temperature and starvation on larval development of Balanus amphitrite Darwin (Cirripedia: Thoracica)

The impact of diatom food species (Chaetoceros calcitrans and Skeletonema costatum), temperature and starvation on the larval development of Balanus amphitrite was evaluated. Starvation threshold levels for different ages of larvae (0- to 5-day-old) fed with C. calcitrans and S. costatum and then starved at 5, 15 and 25 °C temperature were estimated as ultimate recovery hour (URH; denoting the starvation point in hours at the end of which larvae can recover and continue development). Effect of temperature on starvation threshold varied significantly with larval age and food species. The URH declined with larval age at 5 °C, but not at 15 and 25 °C. The URH and grazing rates were high for early instars fed on C. calcitrans, and for advanced instars fed on S. costatum. Carbon gain through feeding was maximum for 2-day-old larvae when fed with C. calcitrans and decreased with larval age. However, when fed with S. costatum carbon gain increased with larval age. This confirms that with development the utility of food types changes. The differences in the carbon gain can be attributed to differences in grazing rate due to variations in the size of the diatom cells, larval intersetular distance, diatom sinking rate and the photo-taxic behavior of larvae. Molting was observed at times when larvae were undergoing starvation and this could be viewed as stress-induced molting, and it differed with the larval age and food organisms.     

Unlocking the potential of metagenomics through replicated experimental design

Metagenomics holds enormous promise for discovering novel enzymes and organisms that are biomarkers or drivers of processes relevant to disease, industry and the environment. In the past two years, we have seen a paradigm shift in metagenomics to the application of cross-sectional and longitudinal studies enabled by advances in DNA sequencing and high-performance computing. These technologies now make it possible to broadly assess microbial diversity and function, allowing systematic investigation of the largely unexplored frontier of microbial life. To achieve this aim, the global scientific community must collaborate and agree upon common objectives and data standards to enable comparative research across the Earth's microbiome. Improvements in comparability of data will facilitate the study of biotechnologically relevant processes, such as bioprospecting for new glycoside hydrolases or identifying novel energy sources.     

Analysis by NMR spectroscopy of the structural homology between the linear and the cyclic peptide recognized by anti-human leukocyte antigen class I monoclonal antibody TP25.99*

The anti-human leukocyte antigen (HLA) class I monoclonal antibody (mAb) TP25.99 has a unique specificity since it recognizes both a conformational and a linear determinant expressed on the beta(2)-mu-associated and beta(2)-mu-free HLA class I heavy chains, respectively. Previously, we reported the identification of a cyclic and a linear peptide that inhibits mAb TP25.99 binding to the beta(2)-mu-associated and beta(2)-mu-free HLA class I heavy chains (S. A. Desai, X. Wang, E. J. Noronha, Q. Zhou, V. Rebmann, H. Grosse-Wilde, F. J. Moy, R. Powers, and S. Ferrone, submitted for publication). The linear X(19) and cyclic LX-8 peptides contain sequence homologous to residues 239-242, 245, and 246 and to residues 194-198, respectively, of HLA class I heavy chain alpha(3) domain. Analysis by two-dimensional transfer nuclear Overhauser effect spectroscopy of the induced solution structures of the linear X(19) and cyclic LX-8 peptides in the presence of mAb TP25.99 showed that the two peptides adopt a similar structural motif despite the lack of sequence homology. The backbone fold is suggestive of a short helical segment followed by a tight turn, reminiscent of the determinant loop region (residues 194-198) on beta(2)-mu-associated HLA class I heavy chains. The structural similarity between the linear X(19) and cyclic LX-8 peptides and the lack of sequence homology suggests that mAb TP25.99 predominantly recognizes a structural motif instead of a consensus sequence.     

Decellularized amnion scaffold with activated PRP: a new paradigm dressing material for burn wound healing

Direct application of amnion has greater risk of immunological rejection and infection. Decellularization is an effective method to lower the risk of immune complications and infections. The bioreactor assembly with multiple cassettes was designed for decellurization of multiple amnions with different cell types simultaneously in single run. A detergent-based protocol was modified to remove all cellular components from amnion and diminish the DNA content to render it non-immunogenic. Amnion (n = 10) were treated with 2% sodium dodecyl sulphate (SDS), 5% dimethyl sulfoxide (DMSO) and 2% sodium deoxycholeate (SD). Decellularized amnion samples were analyzed by haematoxylin–eosin staining (HE), Alcian blue pH 1 (AB-pH-1), 4,6-diamnionidino-2-phenylindol (DAPI), Massion’s trichrome stain, DNA quantification, mechanical testing and scanning electron microscopy (SEM). Histological analysis showed complete removal of cellular components and the histoarchitecture of scaffold remained intact. Amnion scaffold activated with platelet rich plasma (PRP) and calcium chloride composition supported better adherence to the wound than amnion alone. Only single application showed good healing. In vivo assessment of activated amnion revealed stable dressing. It has good promising outcome. At day 7, histologically the wounds treated with activated amnion were almost closed without scarring and showed well differentiated epidermis, proliferation of keratinocytes, hair follicles and basement membrane as compared to controls and silver nitrate gel dressings in a mouse (Mus musculus). Cryopreservation had no adverse effect on the mechanical properties of the amnion scaffold. Cryopreservation of decellularized amnion by Dulbecco’s modified eagle medium (DMEM) was expected to prepare off-the-shelf skin substitutes and preserve them to be immediately available upon request of patients’ needs.     

Intermittent Preventive Treatment of Malaria in Pregnancy with Mefloquine in HIV-Infected Women Receiving Cotrimoxazole Prophylaxis: A Multicenter Randomized Placebo-Controlled Trial

Background

Intermittent preventive treatment in pregnancy (IPTp) with sulfadoxine-pyrimethamine (SP) is recommended for malaria prevention in HIV-negative pregnant women, but it is contraindicated in HIV-infected women taking daily cotrimoxazole prophylaxis (CTXp) because of potential added risk of adverse effects associated with taking two antifolate drugs simultaneously. We studied the safety and efficacy of mefloquine (MQ) in women receiving CTXp and long-lasting insecticide treated nets (LLITNs).

Methods and Findings

A total of 1,071 HIV-infected women from Kenya, Mozambique, and Tanzania were randomized to receive either three doses of IPTp-MQ (15 mg/kg) or placebo given at least one month apart; all received CTXp and a LLITN. IPTp-MQ was associated with reduced rates of maternal parasitemia (risk ratio [RR], 0.47 [95% CI 0.27–0.82]; p = 0.008), placental malaria (RR, 0.52 [95% CI 0.29–0.90]; p = 0.021), and reduced incidence of non-obstetric hospital admissions (RR, 0.59 [95% CI 0.37–0.95]; p = 0.031) in the intention to treat (ITT) analysis. There were no differences in the prevalence of adverse pregnancy outcomes between groups. Drug tolerability was poorer in the MQ group compared to the control group (29.6% referred dizziness and 23.9% vomiting after the first IPTp-MQ administration). HIV viral load at delivery was higher in the MQ group compared to the control group (p = 0.048) in the ATP analysis. The frequency of perinatal mother to child transmission of HIV was increased in women who received MQ (RR, 1.95 [95% CI 1.14–3.33]; p = 0.015). The main limitation of the latter finding relates to the exploratory nature of this part of the analysis.

Conclusions

An effective antimalarial added to CTXp and LLITNs in HIV-infected pregnant women can improve malaria prevention, as well as maternal health through reduction in hospital admissions. However, MQ was not well tolerated, limiting its potential for IPTp and indicating the need to find alternatives with better tolerability to reduce malaria in this particularly vulnerable group. MQ was associated with an increased risk of mother to child transmission of HIV, which warrants a better understanding of the pharmacological interactions between antimalarials and antiretroviral drugs.

Trial registration

ClinicalTrials.gov {"type":"clinical-trial","attrs":{"text":"NCT 00811421","term_id":"NCT00811421"}}NCT 00811421; Pan African Clinical Trials Registry PACTR 2010020001813440 Please see later in the article for the Editors'' Summary     

Sputum mediator profiling and relationship to airway wall geometry imaging in severe asthma

Background

Severe asthma is a heterogeneous disease and the relationship between airway inflammation and airway remodelling is poorly understood. We sought to define sputum mediator profiles in severe asthmatics categorised by CT-determined airway geometry and sputum differential cell counts.

Methods

In a single centre cross-sectional observational study we recruited 59 subjects with severe asthma that underwent sputum induction and thoracic CT. Quantitative CT analysis of the apical segment of the right upper lobe (RB1) was performed. Forty-one mediators in sputum samples were measured of which 21 mediators that were assessable in >50% of samples were included in the analyses.

Results

Independent of airway geometry, sputum MMP9 and IL-1β were elevated in those groups with a high sputum neutrophil count while sputum ICAM was elevated in those subjects with a low sputum neutrophil count. In contrast, sputum CCL11, IL-1α and fibrinogen were different in groups stratified by both sputum neutrophil count and airway geometry. Sputum CCL11 concentration was elevated in subjects with a low sputum neutrophil count and high luminal and total RB1 area, whereas sputum IL1α was increased in subjects with a high sputum neutrophil count and low total RB1 area. Sputum fibrinogen was elevated in those subjects with RB1 luminal narrowing and in those subjects with neutrophilic inflammation without luminal narrowing.

Conclusions

We have demonstrated that sputum mediator profiling reveals a number of associations with airway geometry. Whether these findings reflect important biological phenotypes that might inform stratified medicine approaches requires further investigation.     

An Analysis of Pregnancy-Related Mortality in the KEMRI/CDC Health and Demographic Surveillance System in Western Kenya

Background

Pregnancy-related (PR) deaths are often a result of direct obstetric complications occurring at childbirth.

Methods and Findings

To estimate the burden of and characterize risk factors for PR mortality, we evaluated deaths that occurred between 2003 and 2008 among women of childbearing age (15 to 49 years) using Health and Demographic Surveillance System data in rural western Kenya. WHO ICD definition of PR mortality was used: “the death of a woman while pregnant or within 42 days of termination of pregnancy, irrespective of the cause of death”. In addition, symptoms and events at the time of death were examined using the WHO verbal autopsy methodology. Deaths were categorized as either (i) directly PR: main cause of death was ascribed as obstetric, or (ii) indirectly PR: main cause of death was non-obstetric. Of 3,223 deaths in women 15 to 49 years, 249 (7.7%) were PR. One-third (34%) of these were due to direct obstetric causes, predominantly postpartum hemorrhage, abortion complications and puerperal sepsis. Two-thirds were indirect; three-quarters were attributable to human immunodeficiency virus (HIV/AIDS), malaria and tuberculosis. Significantly more women who died in lower socio-economic groups sought care from traditional birth attendants (p = 0.034), while less impoverished women were more likely to seek hospital care (p = 0.001). The PR mortality ratio over the six years was 740 (95% CI 651–838) per 100,000 live births, with no evidence of reduction over time (χ² linear trend = 1.07; p = 0.3).

Conclusions

These data supplement current scanty information on the relationship between infectious diseases and poor maternal outcomes in Africa. They indicate low uptake of maternal health interventions in women dying during pregnancy and postpartum, suggesting improved access to and increased uptake of skilled obstetric care, as well as preventive measures against HIV/AIDS, malaria and tuberculosis among all women of childbearing age may help to reduce pregnancy-related mortality.     

Cobalamin producers and prokaryotic consumers in the Northwest Atlantic

Cobalamin availability can influence primary productivity and ecological interactions in marine microbial communities. The characterization of cobalamin sources and sinks is a first step in investigating cobalamin dynamics and its impact on productivity. Here, we identify potential cobalamin sources and sinks on the Scotian Shelf and Slope in the Northwest Atlantic Ocean. Functional and taxonomic annotation of bulk metagenomic reads, combined with analysis of genome bins, were used to identify potential cobalamin sources and sinks. Cobalamin synthesis potential was mainly attributed to Rhodobacteraceae, Thaumarchaeota, and cyanobacteria (Synechococcus and Prochlorococcus). Cobalamin remodelling potential was mainly attributed to Alteromonadales, Pseudomonadales, Rhizobiales, Oceanospirilalles, Rhodobacteraceae, and Verrucomicrobia, while potential cobalamin consumers include Flavobacteriaceae, Actinobacteria, Porticoccaceae, Methylophiliaceae, and Thermoplasmatota. These complementary approaches identified taxa with the potential to be involved in cobalamin cycling on the Scotian Shelf and revealed genomic information required for further characterization. The Cob operon of Rhodobacterales bacterium HTCC2255, a strain with known importance in cobalamin cycling, was similar to a major cobalamin producer bin, suggesting that a related strain may represent a critical cobalamin source in this region. These results enable future inquiries that will enhance our understanding of how cobalamin shapes microbial interdependencies and productivity in this region.     

SDS-capped 1-pyrenecarboxaldehyde nanoprobe for selective detection of Cu2+ ion from water samples: Spectroscopic approach

Sodium dodecyl sulfate (SDS)-capped 1-pyrenecarboxaldehyde nanoparticles (PyalNPs) were prepared using a reprecipitation method in an aqueous medium and exhibited red-shifted aggregation-induced enhanced emission (AIEE). The dynamic light scattering (DLS) examination showed narrower particle size distribution with an average particle size of 41 nm, whereas −34.5 mV zeta potential value indicate the negative surface charge and good stability of nanoparticles (NPs) in an aqueous medium. The AIEE was seen at λ_max = 473 nm in a fluorescence spectrum of a PyalNP suspension. In the presence of Cu²⁺ ions, the fluorescence of PyalNPs quenches very significantly, even in the presence of other metal ions like Ba²⁺, Ca²⁺, Cd²⁺, Co²⁺, Al³⁺, Fe²⁺, Hg²⁺, Ni²⁺ and Mg²⁺. The changes in the fluorescence lifetime of PyalNPs in the presence of Cu²⁺ ions suggested that the type of quenching was dynamic. The fluorescence quenching data for the NPs suspension fitted well into a typical Stern–Volmer relationship in the concentration range 1.0–25 μg/ml of Cu²⁺ ions. The estimated value of the correlation coefficient R² = 0.9877 was close to 1 and showed the linear relationship between quenching data and Cu²⁺ ion concentration. The limit of detection (LOD) was found to be 0.94 ng/ml and is far below the tolerable intake limit value of 1.3 μg/ml accepted by the World Health Organization for Cu²⁺ ions in drinking water. The fluorescence quenching approach for a SDS-capped Pyal nanosuspension for copper ion quantification is of high specificity and coexisting ions were found to interfere very negligibly. The developed method was successfully applied for the estimation of copper ions in river water samples.