Effect of a patient-centered hypertension delivery strategy on all-cause mortality: Secondary analysis of SEARCH,a community-randomized trial in rural Kenya and Uganda

BackgroundHypertension treatment reduces morbidity and mortality yet has not been broadly implemented in many low-resource settings, including sub-Saharan Africa (SSA). We hypothesized that a patient-centered integrated chronic disease model that included hypertension treatment and leveraged the HIV care system would reduce mortality among adults with uncontrolled hypertension in rural Kenya and Uganda.Methods and findingsThis is a secondary analysis of the SEARCH trial (NCT:01864603), in which 32 communities underwent baseline population-based multidisease testing, including hypertension screening, and were randomized to standard country-guided treatment or to a patient-centered integrated chronic care model including treatment for hypertension, diabetes, and HIV. Patient-centered care included on-site introduction to clinic staff at screening, nursing triage to expedite visits, reduced visit frequency, flexible clinic hours, and a welcoming clinic environment. The analytic population included nonpregnant adults (≥18 years) with baseline uncontrolled hypertension (blood pressure ≥140/90 mm Hg). The primary outcome was 3-year all-cause mortality with comprehensive population-level assessment. Secondary outcomes included hypertension control assessed at a population level at year 3 (defined per country guidelines as at least 1 blood pressure measure <140/90 mm Hg on 3 repeated measures). Between-arm comparisons used cluster-level targeted maximum likelihood estimation.Among 86,078 adults screened at study baseline (June 2013 to July 2014), 10,928 (13%) had uncontrolled hypertension. Median age was 53 years (25th to 75th percentile 40 to 66); 6,058 (55%) were female; 677 (6%) were HIV infected; and 477 (4%) had diabetes mellitus. Overall, 174 participants (3.2%) in the intervention group and 225 participants (4.1%) in the control group died during 3 years of follow-up (adjusted relative risk (aRR) 0.79, 95% confidence interval (CI) 0.64 to 0.97, p = 0.028). Among those with baseline grade 3 hypertension (≥180/110 mm Hg), 22 (4.9%) in the intervention group and 42 (7.9%) in the control group died during 3 years of follow-up (aRR 0.62, 95% CI 0.39 to 0.97, p = 0.038). Estimated population-level hypertension control at year 3 was 53% in intervention and 44% in control communities (aRR 1.22, 95% CI 1.12 to 1.33, p < 0.001). Study limitations include inability to identify specific causes of death and control conditions that exceeded current standard hypertension care.ConclusionsIn this cluster randomized comparison where both arms received population-level hypertension screening, implementation of a patient-centered hypertension care model was associated with a 21% reduction in all-cause mortality and a 22% improvement in hypertension control compared to standard care among adults with baseline uncontrolled hypertension. Patient-centered chronic care programs for HIV can be leveraged to reduce the overall burden of cardiovascular mortality in SSA.Trial registrationClinicalTrials.gov {"type":"clinical-trial","attrs":{"text":"NCT01864603","term_id":"NCT01864603"}}NCT01864603.

Matthew Hickey and co-workers report on outcomes of the SEARCH trial of hypertension screening and care in sub-Saharan Africa.     

Studies on PVP hydrogel-supported luminol chemiluminescence: 1. Kinetic and mechanistic aspects using multivariate factorial analysis.

The chemiluminescent oxidation of luminol by hydrogen peroxide in the presence of hemin is revisited in an UV-C cross-linked PVP hydrogel. Chemiluminescence properties such as initial light intensity (I(0)), area of emission (S) and observed rate constants (k(obs)) are studied, varying the concentration of all reactants using a multivariate factorial approach.     

High Temperatures and Net CO2 Uptake, Growth, and Stem Damage for the Hemiepiphytic Cactus Hylocereus undatus1

Hylocereus undatus, which is native to tropical forests experiencing moderate temperatures, would not be expected to tolerate the extremely high temperatures that can be tolerated by cacti native to deserts. Nevertheless, total daily net CO₂ uptake by this hemiepiphytic cactus, which is widely cultivated for its fruits, was optimal at day/night air temperatures of 30/20°C, temperatures that are higher than those optimal for daily net CO₂ uptake by cacti native to arid and semiarid areas. Exposure to 35/25°C for 30 weeks led to lower net CO₂ uptake than at 10 weeks; exposure to 40/30°C led to considerable necrosis visible on the stems at 6 weeks and nearly complete browning of the stems by 19 weeks. Dry mass gain over 31 weeks was greatest for plants at 30/20°C, with root growth being especially noteworthy and root dry mass gain representing an increasing percentage of plant dry mass gain as day/night air temperatures were increased. Viability of chlorenchyma cells, assayed by the uptake of the vital stain neutral red into the central vacuoles, was decreased 50 percent by a one‐hour treatment at 55°C compared with an average of 64°C for 18 species of cacti native to deserts. The lower high‐temperature tolerance for H. undatus reflected its low high‐temperature acclimation of only 1.4°C as growth temperatures were raised by 10°C compared with an average acclimation of 5.3°C for the other 18 species of cacti. Thus, this tropical hemiepiphytic cactus is not adapted to day/night air temperatures above ca 40/30°C, although its net CO₂ uptake is optimal at the relatively high day/night air temperatures of 30/20°C.     

A comparative study of the action of melittin on sphingomyelin and phosphatidylcholine bilayers

To investigate whether lipid solubilization is of relevance in describing the interaction between melittin and biological membranes, we studied melittin-induced polymorphism using model membranes composed of the biological lipid sphingomyelin (bovine brain). The behavior of the system was monitored by solid state ³¹P-NMR and turbidity measurements and compared to the peptides well-characterized action on the synthetic lipid dipalmitoylphosphatidylcholine. It was found that melittin-induced macroscopic changes of sphingomyelin membranes are qualitatively the same as in the case of dipalmitoylphosphatidylcholine bilayers. The sphingomyelin/melittin system is thus proposed to show a reversible vesicle-to-disc transition (fluid-to-gel phase) through an intermediate fusion or aggregation event centered at the main transition temperature, T_m, as reported in the case of saturated phosphatidylcholine. In the case of spontaneous disc formation at 37 °C, the lipid-to-peptide molar ratio in the discoidal objects was determined to be approximately 20 for dipalmitoylphosphatidylcholine and about 12 in the case of natural sphingomyelin. Melittin partition coefficients between membranes and the aqueous medium at 37 °C were found to be 6.1±0.8 mm ^–1 and 3.7±0.4 mm ^–1 for sphingomyelin and dipalmitoylphosphatidylcholine, respectively. For very high peptide quantities (lipid-to-peptide molar ratio, R_i≤5) mixed micelles are formed over the entire temperature range (20° to 60 °C) for both kinds of lipids.     

Carbon and nitrogen in the root-zone of barley (Hordeum vulgare L.) supplied with nitrogen fertilizer at two rates

Below-ground carbon (C) production and nitrogen (N) flows in the root-zone of barley supplied with high or low amounts of N-fertilizer were investigated. Interest was focused on the effect of the level of N-fertilizer on the production of root-derived C and on gross immobilization (i) and gross mineralization (m) rates. The plants were grown for 46 days in a sandy loam soil. Principles of pool dilution and changes in ¹⁵N pool abundances were used in conjunction with mathematical modelling to calculate the flows of N. N was applied at a high or a low rate, as (¹⁵NH₄)₂SO₄ solution (17.11 atom% ¹⁵N excess), before sowing. Nitrification was inhibited by using nitrapyrin (N-Serve). Pots were sampled four or five times during the experimental period, i.e. 0, 22, 30, 38 and 46 days after germination. On the three last sampling occasions, samples were also collected from pots in a growth chamber with ¹⁴C-labelled atmosphere.The release of ¹⁴C, measured as the proportion of the total ¹⁴C translocated below ground, was higher in the high-N treatment, but the differences between treatments were small. Our results were not conclusive in demonstrating that high-N levels stimulate the decomposition and microbial utilization of root-released materials. However, the internal circulation of soil-N, calculated N fluxes (m), which were in accordance with C mineralization rates and amounts of unlabelled N found in the plants (PU), suggested that the decomposition of native soil organic matter was hampered in the high-N treatment. Apparently, towards the end of the experimental period, microorganisms in the low-N treatment used C from soil organic matter to a greater extent than C they used from root released material, presumably because lower amounts of mineral N were available to microorganisms in the low-N treatment. Immobilization of N appeared to be soil driven (organisms decomposing soil organic matter account for the N demand) at low-N and root-driven (organisms decomposing roots and root-derived C account for the N demand) at high-N.Abbreviations AU Ammonium N-unlabelled - AL Ammonium N-labelled - AT Ammonium N-labelled and unlabelled (total) - NU Nitrate N-unlabelled - OU Organic N-unlabelled - OL Organic N-labelled - OT Organic N-total - PU Plant N-unlabelled (shoots and roots) - PL Plant N-labelled (shoots and roots) - PT Plant N-total (shoots and roots) - SL Sink or source of N-labelled - S Source or sink of N, mainly to and from the outer part of the cylinder - SU Sink or source of N-unlabelled - m Mineralization rate - i Immobilization rate - ua Uptake of ammonium - un Uptake of nitrate - la Loss of ammonium.     

Evidence for a human-specific Escherichia coli clone

Escherichia coli is a widespread commensal of the vertebrate intestinal tract. Until recently, no strong association between a particular clone and a given host species has been found. However, members of the B2 subgroup VIII clone with an O81 serotype appear to be human host specific. To determine the degree of host specificity exhibited by this clone, a PCR-based assay was used to screen 723 faecal and clinical isolates from humans, and 904 faecal isolates from animals. This clone was not detected among the animal isolates, but was discovered in people living in Africa, Europe and South America. The clone is rarely isolated from people suffering from intestinal or extraintestinal disease and is avirulent in a mouse model of extraintestinal infection. Fine-scale epidemiological analysis suggests that this clone is competitively dominant relative to other members of the B2 phylogenetic group and that it has increased in frequency over the past 20 years. This clone appears to be a good candidate for use as a probiotic, and may be suitable as an indicator of human faecal contamination in microbial source tracking studies.     

Improved proteome coverage by using iTRAQ labelling and peptide OFFGEL fractionation

Background  

The development of mass spectrometric techniques and fractionation methods now allows the investigation of very complex protein mixtures ranging from subcellular structures to tissues. Nevertheless, this work is particularly difficult due to the wide dynamic range of protein concentration in eukaryotic tissues. In this paper, we present a shotgun method whereby the peptides are fractionated using OFFGEL electrophoresis after iTRAQ labelling.     

The role of phytosterols in plant adaptation to temperature

Membranes of composition approaching those found in “rafts” of plants, fungi and mammals were investigated by means of solidstate ²H-NMR, using deuterated dipalmitoyl-phosphatidylcholine (²H-DPPC) as a reporter. The dynamics of such membranes was determined through measuring of membrane ordering or disordering properties. The presence of the liquid-ordered, lo, phase, as an indicator of rigid sterol-sphingolipid domains, was detected in all cases. Of great interest, the dynamics of mixtures mimicking rafts in plants showed the lesser temperature sensitivity to thermal shocks. The presence of an additional ethyl group branched on the alkyl chain of major plant sterols (sitosterol and stigmasterol) is proposed as reinforcing the membrane cohesion. The fine tuning of the sterol structure thus appears to be the evolution response for plant adaptation to large temperature variations.Key words: sitosterol, stigmasterol and glucosylcerebrosides, regulation of membrane dynamics, membrane rafts, deuterium NMRIt is widely recognized that lipids play multiple roles that either individually or collectively influence cell processes. Glycerolipids and sphingolipids through charge and structure are involved in DNA replication, protein translocation, cell recognition, signalling pathways, energetic, signal transduction, and cell trafficking. Together with diacylglycerols their collective properties modulate lipid polymorphism, through phase transitions (lamellar, hexagonal, cubic, micelles), which are involved in enzyme conformational changes, cell division, cell fusion, and apoptosis.¹Sterols, the third lipid class, also regulate biological processes and sustain the domain structure of cell membranes where they are considered as membrane reinforcers.^2,3 While cholesterol (CHO) is the major sterol of vertebrates, ergosterol plays a key role in fungi. Plants usually possess more complex sterol compositions. Stigmasterol (STI) and sitosterol (SIT), two 24-ethyl sterols, are major constituents of the sterol profiles of plant species. They are involved in the embryonic growth of plants.^4,5 Sterols are critical for the formation of liquid-ordered (lo) lipid domains (lipid rafts) that are supposed to play an important role in fundamental biological processes like signal transduction, cellular sorting, cytoskeleton reorganization and infectious diseases.^6,7 In plants, specialized lipid domains are involved in the polarized growth of pollen tube and root hair⁸ and the asymmetric growth of plant cells is in general due to the asymmetric distribution of membrane components.We recently documented the effect of sitosterol and stigmasterol, two major plant sterols, on the structure and dynamics of membranes whose composition is representative of domains (rafts) in plants.⁹ Liposomes of phytosterols associated with glucosylcerebroside (GC) and with deuterium-labelled dipalmitoylphosphatidylcholine (²H-DPPC) were analysed with deuterium solid state nuclear magnetic resonance (²H-NMR). For comparison, membrane systems representative of raft composition in fungi and mammals were also investigated. ²H-NMR is known to be the best non-invasive technique to analyse membrane dynamics¹⁰ because it is non-destructive and because replacement of DPPC protons with their deuterium isotope brings very little membrane perturbation.^11,12 Acyl chain deuteration affords analysis of both structure and dynamics of the hydrophobic membrane interior. Spectra such as that shown in Figure 1 insert, allow detection of the lo phase, characteristic of a membrane state half-way between solid-ordered (so) and liquid-disordered (ld) states. The so state, also called “gel”, is found at low temperatures (below 35°C), when membranes are essentially composed of sphingomyelins (SM)¹³ or GC (Fig. 1). This membrane state allows little biological function because in forbids membrane trafficking due to its very rigid state (order parameter close to 1). In turn, the ld or “fluid” state is found at high temperatures, in the absence of SM, GC and sterols (low order parameter). At the opposite such a high membrane dynamics may lead to excessive membrane passages. Following with ²H-NMR the temperature behaviour of membrane systems containing GC and plant sterols, we found that the so-ld, order-disorder, transition was totally abolished: SIT and STI fluidized the so state and ordered the ld state to produce the lo state where membrane fluctuations vary smoothly with temperature (Fig. 1). This effect was already documented with CHO in mammals^14–16 but on a much narrower temperature range. The case of the fungus system was found in between that of plants and mammals.Open in a separate windowFigure 1Regulation of temperature-driven membrane dynamics by plant sterols. Central panel: first spectral moment (left y-axis) or order parameter (right y-axis) as a function of temperature; solid line: ²H-DPPC with glucosylcerebroside; open circles: plus stigmasterol; filled circles: plus sitosterol. Insert: ²H-NMR spectrum typical of a liquid-ordered, lo, state. Left panel: schematics of solid-ordered, so (gel), and liquid-disordered, ld (fluid), membrane states. Right panel: schematics of the lo (raft) membrane state together with the structures of cholesterol and sitosterol. Adapted from reference ⁹.Summarizing, it appears that plant membranes of “raft” composition are less sensitive to temperature variations than those of animals. This suggests that cell membrane components like sitosterol, stigmasterol and glucosylcere-brosides, which are typical of plants, are produced in order to extend the temperature range in which membrane-associated biological processes can take place. This observation is well in accordance with the fact that plants have to face higher temperature variations than animals, which usually can either regulate their body temperature or change their location in order to avoid extreme heat or coldness.Compared to cholesterol, the two phytosterols possess additional ethyl groups branched on C-24 (Fig. 1). We proposed that the presence of an additional ethyl group may reinforce the attractive van der Waals interactions leading to more membrane cohesion and therefore less temperature sensitivity. Our results also suggest that domains of smaller size would be promoted in the presence of phytosterols and especially with sitosterol. Such domains may be viewed as dynamic, with sterols laterally exchanging at the microsecond time scale.¹⁴ In plant cells, enzymes transfer alkyl groups to the C-24 of sterols. If we suppose that the relative activities of the different branches of the plant sterol biosynthesis are regulated, the concentrations of major sterols in plants, like sitosterol, stigmasterol, and cholesterol could be controlled.^4,17 This shows the importance of equilibrated sterol concentrations for plant growth and development. Sterols have been historically considered as membrane reinforcers because they bring order to membranes.^2,3Our works^{9,15,16,18,19} show that they could better be named as “membrane dynamics regulators”, by maintaining the membrane in a state of microfluidity suitable for cell function on large temperature scales. It thus appears that a fine tuning of the sterol structure, i.e., the presence of branched ethyl groups in plant sterols increasing membrane cohesion through formation of smaller membrane domains, may be the evolution response for plant adaptation to large temperature variations.     

A Proposed EPR Approach to Evaluating Agonist Binding Site of a Peptide Receptor

Angiotensin II (Ang II) and its transmembrane AT₁ receptor were selected in order to test an innovative strategy that might allow the assessment of the agonist binding site in the receptor molecule. With the use of the 2,2,6,6-tetramethylpiperidine-1-oxyl-4-amino-4-carboxylic acid (TOAC) paramagnetic probe, a biologically active agonist (TOAC¹-Ang II), as well as an inactive control (TOAC⁴-Ang II) analogs were mixed in solution with various synthesized AT₁ fragments. Comparative intermolecular interactions, as estimated by analyzing the EPR spectra of solutions, suggested the existence of an agonist binding site containing a sequence composed of portions of the N-terminal (13-17) and the third extracellular loop (266-278) fragments of the AT₁ molecule. Therefore, this combined EPR-TOAC approach shows promise as an alternative for use also in other applications related to specific intermolecular association processes. In memoriam of Professor Paiva.     

E2F and p53 induce apoptosis independently during Drosophila development but intersect in the context of DNA damage

In mammalian cells, RB/E2F and p53 are intimately connected, and crosstalk between these pathways is critical for the induction of cell cycle arrest or cell death in response to cellular stresses. Here we have investigated the genetic interactions between RBF/E2F and p53 pathways during Drosophila development. Unexpectedly, we find that the pro-apoptotic activities of E2F and p53 are independent of one another when examined in the context of Drosophila development: apoptosis induced by the deregulation of dE2F1, or by the overexpression of dE2F1, is unaffected by the elimination of dp53; conversely, dp53-induced phenotypes are unaffected by the elimination of dE2F activity. However, dE2F and dp53 converge in the context of a DNA damage response. Both dE2F1/dDP and dp53 are required for DNA damage-induced cell death, and the analysis of rbf1 mutant eye discs indicates that dE2F1/dDP and dp53 cooperatively promote cell death in irradiated discs. In this context, the further deregulation in the expression of pro-apoptotic genes generates an additional sensitivity to apoptosis that requires both dE2F/dDP and dp53 activity. This sensitivity differs from DNA damage-induced apoptosis in wild-type discs (and from dE2F/dDP-induced apoptosis in un-irradiated rbf1 mutant eye discs) by being dependent on both hid and reaper. These results show that pro-apoptotic activities of dE2F1 and dp53 are surprisingly separable: dp53 is required for dE2F-dependent apoptosis in the response to DNA damage, but it is not required for dE2F-dependent apoptosis caused simply by the inactivation of rbf1.