Direct evidence of lower viral replication rates in vivo in human immunodeficiency virus type 2 (HIV-2) infection than in HIV-1 infection

Studies have shown that human immunodeficiency virus type 2 (HIV-2) is less pathogenic than HIV-1, with a lower rate of disease progression. Similarly, plasma viral loads are lower in HIV-2 infection, suggesting that HIV-2 replication is restricted in vivo in comparison to that of HIV-1. However, to date, in vivo studies characterizing replication intermediates in the viral life cycle of HIV-2 have been limited. In order to test the hypothesis that HIV-2 has a lower replication rate in vivo than HIV-1 does, we quantified total viral DNA, integrated proviral DNA, cell-associated viral mRNA, and plasma viral loads in peripheral blood samples from groups of therapy-na?ve HIV-1-infected (n = 21) and HIV-2-infected (n = 18) individuals from Dakar, Senegal, with CD4(+) T-cell counts of >200/microl. Consistent with our previous findings, total viral DNA loads were similar between HIV-1 and HIV-2 and plasma viral loads were higher among HIV-1-infected individuals. Proportions of DNA in the integrated form were also similar between these viruses. In contrast, levels of viral mRNA were lower in HIV-2 infection. Our study indicates that HIV-2 is able to establish a stable, integrated proviral infection in vivo, but that accumulation of viral mRNA is attenuated in HIV-2 infection relative to that in HIV-1 infection. The differences in viral mRNA are consistent with the differences in plasma viral loads between HIV-1 and HIV-2 and suggest that lower plasma viral loads, and possibly the attenuated pathogenesis of HIV-2, can be explained by lower rates of viral replication in vivo.     

Effect of weight loss on predicted cardiovascular risk: change in cardiac risk after bariatric surgery

Objective: Our goal was to assess the effect of bariatric surgery on cardiovascular risk estimations of preventable, long‐term adverse outcomes. Research Methods and Procedures: We performed a population‐based, historical cohort study between 1990 and 2003 of 197 consecutive patients from Olmsted County, MN, with Class II to III obesity (defined as BMI ≥35 kg/m²) treated with Roux‐en‐Y gastric bypass and 163 non‐operative patients assessed in a weight‐reduction program. We used the observed change in cardiovascular risk factors and risk models derived from data from the National Health and Nutrition Examination Survey (NHANES) I and the NHANES I Epidemiological Follow‐up Study (NHEFS) to calculate the predicted impact on cardiovascular events and mortality for the operative and non‐operative groups. Results: Mean follow‐up was 3.3 years. Hypertension, diabetes, and dyslipidemia all improved after bariatric surgery. The estimated 10‐year risk for cardiovascular events for the operative group decreased from 37% at baseline to 18% at follow‐up, while the estimated risk for the non‐operative group did not change from 30% at baseline to 30% at follow‐up. Risk modeling to predict 10‐year outcomes estimated 4 overall deaths and 16 cardiovascular events prevented by bariatric surgery per 100 patients compared with the non‐operative group. Conclusions: Bariatric surgery induces an improvement in cardiovascular risk factors in patients with Class II to III obesity. Weight loss predicts a major, 10‐year reduction in cardiovascular events and deaths. Bariatric surgery should be considered as an alternative approach to reduce cardiovascular risk in patients with Class II to III obesity.     

Spherical Deconvolution of Multichannel Diffusion MRI Data with Non-Gaussian Noise Models and Spatial Regularization

Spherical deconvolution (SD) methods are widely used to estimate the intra-voxel white-matter fiber orientations from diffusion MRI data. However, while some of these methods assume a zero-mean Gaussian distribution for the underlying noise, its real distribution is known to be non-Gaussian and to depend on many factors such as the number of coils and the methodology used to combine multichannel MRI signals. Indeed, the two prevailing methods for multichannel signal combination lead to noise patterns better described by Rician and noncentral Chi distributions. Here we develop a Robust and Unbiased Model-BAsed Spherical Deconvolution (RUMBA-SD) technique, intended to deal with realistic MRI noise, based on a Richardson-Lucy (RL) algorithm adapted to Rician and noncentral Chi likelihood models. To quantify the benefits of using proper noise models, RUMBA-SD was compared with dRL-SD, a well-established method based on the RL algorithm for Gaussian noise. Another aim of the study was to quantify the impact of including a total variation (TV) spatial regularization term in the estimation framework. To do this, we developed TV spatially-regularized versions of both RUMBA-SD and dRL-SD algorithms. The evaluation was performed by comparing various quality metrics on 132 three-dimensional synthetic phantoms involving different inter-fiber angles and volume fractions, which were contaminated with noise mimicking patterns generated by data processing in multichannel scanners. The results demonstrate that the inclusion of proper likelihood models leads to an increased ability to resolve fiber crossings with smaller inter-fiber angles and to better detect non-dominant fibers. The inclusion of TV regularization dramatically improved the resolution power of both techniques. The above findings were also verified in human brain data.     

Biofilm formation in spent nuclear fuel pools and bioremediation of radioactive water.

Microbiological studies of spent nuclear fuel pools at the Cofrentes Nuclear Power Plant (Valencia, Spain) were initiated to determine the microbial populations in the pools' water. Biofilm formation at the nuclear power plant facilities and the potential use of those microbial populations in the bioremediation of radioactive water were also studied. Biofilm formation was analyzed by immersing different austenitic stainless steel coupons (UNS S30400, UNS S30466, UNS S31600), as well as balls of stainless steel (UNS S44200) and titanium (99.9%) in a spent nuclear fuel pool (under static and dynamic conditions) for 34 months. Epifluorescence microscopy and scanning electron microscopy revealed that biofilm formed on the samples, in spite of the radioactive and oligotrophic conditions of the water. Based on standard culture methods and sequencing of 16S rDNA fragments, 57 bacteria belonging to alpha-, beta-, and gamma-Proteobacteria, Firmicutes and Actinobacteridae were identified in the biofilms. The radioactivity of the biofilm was measured using gamma-ray spectrometry, which revealed that biofilms were able to retain radionuclides, especially (60)Co. Using metallic materials to decontaminate radioactive water could become a new approach for bioremediation.     

A high-protein neonatal formula induces a temporary reduction of adiposity and changes later adipocyte physiology

The high-protein content of formula offered to low-birth weight babies is suspected to increase the risk of obesity later in life. This study assesses the immediate and subsequent effects of a protein intake in excess during suckling on hormonal and metabolic status and adipose tissue features in a porcine model of intrauterine growth restriction. Piglets were fed milk replacers formulated to provide an adequate (AP) or a high (HP) protein supply from day 2 to day 28. A subset of piglets was killed at day 28. After weaning, the remaining piglets had free access to the same solid high-fat diet until day 160. From day 2 to day 28, HP piglets had a greater daily weight gain (P < 0.05). Relative weight of perirenal adipose tissue (PAT), adipocyte mean diameters, activities of lipogenic enzymes in PAT and subcutaneous adipose tissue (SCAT), and leptinemia were lower (P < 0.05) in HP piglets than in AP piglets. Genes related to glucose utilization and lipid anabolism in PAT and SCAT were (P < 0.05) or tended (P < 0.1) to be downregulated in HP piglets. At day 160, adipocytes were enlarged, whereas lipogenic rates in adipocytes were reduced (P < 0.05) in SCAT of HP compared with AP pigs. Percent body fat, mRNA levels of genes controlling lipid metabolism, and plasma concentrations of hormones and metabolites were similar in HP and AP pigs. In conclusion, a HP neonatal formula induced a temporary reduction of adiposity and changed adipocyte physiology at peripubertal age.     

Identification and functional validation of the novel antimalarial resistance locus PF10_0355 in Plasmodium falciparum

The Plasmodium falciparum parasite's ability to adapt to environmental pressures, such as the human immune system and antimalarial drugs, makes malaria an enduring burden to public health. Understanding the genetic basis of these adaptations is critical to intervening successfully against malaria. To that end, we created a high-density genotyping array that assays over 17,000 single nucleotide polymorphisms (～ 1 SNP/kb), and applied it to 57 culture-adapted parasites from three continents. We characterized genome-wide genetic diversity within and between populations and identified numerous loci with signals of natural selection, suggesting their role in recent adaptation. In addition, we performed a genome-wide association study (GWAS), searching for loci correlated with resistance to thirteen antimalarials; we detected both known and novel resistance loci, including a new halofantrine resistance locus, PF10_0355. Through functional testing we demonstrated that PF10_0355 overexpression decreases sensitivity to halofantrine, mefloquine, and lumefantrine, but not to structurally unrelated antimalarials, and that increased gene copy number mediates resistance. Our GWAS and follow-on functional validation demonstrate the potential of genome-wide studies to elucidate functionally important loci in the malaria parasite genome.     

KAP degradation by calpain is associated with CK2 phosphorylation and provides a novel mechanism for cyclosporine A-induced proximal tubule injury

The use of cyclosporine A (CsA) is limited by its severe nephrotoxicity that includes reversible vasoconstrictor effects and proximal tubule cell injury, the latter associated whith chronic kidney disease progression. The mechanisms of CsA-induced tubular injury, mainly on the S3 segment, have not been completely elucidated. Kidney androgen-regulated protein (KAP) is exclusively expressed in kidney proximal tubule cells, interacts with the CsA-binding protein cyclophilin B and its expression diminishes in kidneys of CsA-treated mice. Since we reported that KAP protects against CsA toxicity in cultured proximal tubule cells, we hypothesized that low KAP levels found in kidneys of CsA-treated mice might correlate with proximal tubule cell injury. To test this hypothesis, we used KAP Tg mice developed in our laboratory and showed that these mice are more resistant to CsA-induced tubular injury than control littermates. Furthermore, we found that calpain, which was activated by CsA in cell cultures and kidney, is involved in KAP degradation and observed that phosphorylation of serine and threonine residues found in KAP PEST sequences by protein kinase CK2 enhances KAP degradation by calpain. Moreover, we also observed that CK2 inhibition protected against CsA-induced cytotoxicity. These findings point to a novel mechanism for CsA-induced kidney toxicity that might be useful in developing therapeutic strategies aimed at preventing tubular cell damage while maintaining the immunosuppressive effects of CsA.     

Development of a simple disposable six minibioreactor system for suspension mammalian cell culture

A simple disposable six minibioreactor system has been developed in order to perform multiple cell culture experiments in parallel, as a tool to accelerate experimentation in cell culture optimization. The system consists of a fixed part containing all instrumentation, sensors and actuators, and a disposable part, a compact unit with six minibioreactors with 10–15 mL of working volume each. This single-use unit is made of transparent biocompatible plastic material (polystyrene). Each one of the minibioreactors is equipped with agitation, headspace aeration supply and two optical probes, one for total cells measurement and pH, and another for dissolved oxygen measurement (and consequently the evaluation of Oxygen Uptake Rate, OUR). As an example of application, the performance of the system is successfully demonstrated for the culture of hybridoma cells growing in suspension under different conditions. The results allowed confirming the reproducibility of the system, and the feasibility to follow-up continuously the differences in cell growth, pH, pO₂ and OUR evolution when hybridoma cells are cultured in different experimental conditions. For this, three different sets of experiments are considered. First, the use of the same culture medium DMEM supplemented with 10% fetal calf serum in all six minibioreactors. Second, the use of DMEM supplemented with three different FCS percentages (0, 1 and 10%) in two minibioreactors each. Third, the use of two different media (DMEM supplemented with 10% FCS and a chemically defined medium) in three minibioreactors each.     

Maternal malaria induces a procoagulant and antifibrinolytic state that is embryotoxic but responsive to anticoagulant therapy

Low birth weight and fetal loss are commonly attributed to malaria in endemic areas, but the cellular and molecular mechanisms that underlie these poor birth outcomes are incompletely understood. Increasing evidence suggests that dysregulated hemostasis is important in malaria pathogenesis, but its role in placental malaria (PM), characterized by intervillous sequestration of Plasmodium falciparum, proinflammatory responses, and excessive fibrin deposition is not known. To address this question, markers of coagulation and fibrinolysis were assessed in placentae from malaria-exposed primigravid women. PM was associated with significantly elevated placental monocyte and proinflammatory marker levels, enhanced perivillous fibrin deposition, and increased markers of activated coagulation and suppressed fibrinolysis in placental plasma. Submicroscopic PM was not proinflammatory but tended to be procoagulant and antifibrinolytic. Birth weight trended downward in association with placental parasitemia and high fibrin score. To directly assess the importance of coagulation in malaria-induced compromise of pregnancy, Plasmodium chabaudi AS-infected pregnant C57BL/6 mice were treated with the anticoagulant, low molecular weight heparin. Treatment rescued pregnancy at midgestation, with substantially decreased rates of active abortion and reduced placental and embryonic hemorrhage and necrosis relative to untreated animals. Together, the results suggest that dysregulated hemostasis may represent a novel therapeutic target in malaria-compromised pregnancies.     

Seroprevalence of Pertussis in Senegal: A Prospective Study

Background

Pertussis, also known as whooping cough, is a vaccine-preventable respiratory disease caused by Bordetella pertussis infection, against which Senegalese children are immunized with the diphtheria-tetanus-whole cell pertussis vaccine (DTwP). Seroepidemiology of pertussis has been widely described in industrialized countries, but rare are the studies referring to it in developing countries.

Methods

We conducted a longitudinal survey in Northern Senegal to investigate the epidemiology of B. pertussis by evaluating the IgG antibody (Ab) response against pertussis toxin (PT). A cohort of 410 children aged 1 to 9 from five villages in the Middle Senegal River Valley were followed-up for 18 months. During that period, five visits were made to assess the immunological status of the children.

Principal Findings

PT-specific IgG responses were significantly different according to age. Until the age of 3, there was a decrease in the Ab response, which then increased in the older groups. Assessment of IgG antibodies to PT (IgG-PT) suggested evidence of recent exposures to the pathogen. Surprisingly, in one of the five villages the average Ab response to PT was very low at all ages during the first 6 months of the study. At the third visit, IgG-PT concentrations peaked to very high levels, to slightly decline at the end of the survey. This indicates an outbreak of B. pertussis, whereas in the other villages a pertussis endemic profile could be observed.

Conclusions

Pertussis is endemic in Northern Senegal despite the introduction of vaccination. The circulation of the bacteria seems to differ between geographic locations and over time. A more complete understanding of the epidemiology of pertussis and its environmental determinants could provide information to adapt vaccination programs.