The Last Swiddens of Sarawak, Malaysia

Swidden cultivation was observed to be under pressure but still persisting in many areas in Sarawak, Malaysia around 2000–2003. Since then rapid development of smallholder oil palm and rubber, continuing urbanization and rural to urban migration appear to have considerably reduced the area under swidden cultivation. With the aim of understanding the extent and impacts of this development, 55 households in three communities that were interviewed in 2002–2003 were re-interviewed in 2011. In an area with rapid oil palm development, the households engaged in smallholder oil palm production have experienced considerable improvements in income and wealth whereas the other households have experienced more limited wealth increases or even a decline in income. Many households have decreased or abandoned cultivation of upland rice, which used to be the core of the swidden cultivation system, and the upland soils in the area are now dominated by oil palm. In another area, where no oil palm development has taken place because of a hydroelectric dam, upland rice fields under swidden cultivation have also decreased and new high yielding rubber is now being planted because of the favorable rubber prices. Moreover, tourism has in this area gained further economic importance and overtaken agriculture as the main economic activity of households. The demise of swidden has not yet occurred in Sarawak, but a continued decline has been observed. However, there is a possibility that the new smallholder oil palm and rubber may provide an opportunity for a new type of ‘productive fallow’ that will allow continued cultivation of upland rice on a small scale.     

Induced pluripotent stem cells used to reveal drug actions in a long QT syndrome family with complex genetics

Understanding the basis for differential responses to drug therapies remains a challenge despite advances in genetics and genomics. Induced pluripotent stem cells (iPSCs) offer an unprecedented opportunity to investigate the pharmacology of disease processes in therapeutically and genetically relevant primary cell types in vitro and to interweave clinical and basic molecular data. We report here the derivation of iPSCs from a long QT syndrome patient with complex genetics. The proband was found to have a de novo SCN5A LQT-3 mutation (F1473C) and a polymorphism (K897T) in KCNH2, the gene for LQT-2. Analysis of the biophysics and molecular pharmacology of ion channels expressed in cardiomyocytes (CMs) differentiated from these iPSCs (iPSC-CMs) demonstrates a primary LQT-3 (Na⁺ channel) defect responsible for the arrhythmias not influenced by the KCNH2 polymorphism. The F1473C mutation occurs in the channel inactivation gate and enhances late Na⁺ channel current (I_NaL) that is carried by channels that fail to inactivate completely and conduct increased inward current during prolonged depolarization, resulting in delayed repolarization, a prolonged QT interval, and increased risk of fatal arrhythmia. We find a very pronounced rate dependence of I_NaL such that increasing the pacing rate markedly reduces I_NaL and, in addition, increases its inhibition by the Na⁺ channel blocker mexiletine. These rate-dependent properties and drug interactions, unique to the proband’s iPSC-CMs, correlate with improved management of arrhythmias in the patient and provide support for this approach in developing patient-specific clinical regimens.     

Synthesis of 3, N4-Dimethylcytidine

Abstract

Two procedures are described for the synthesis of 3, N⁴-dimethylcytidine, a compound usually obtained in only trace quantities.     

Olig2/Plp-positive progenitor cells give rise to Bergmann glia in the cerebellum

NG2 (nerve/glial antigen2)-expressing cells represent the largest population of postnatal progenitors in the central nervous system and have been classified as oligodendroglial progenitor cells, but the fate and function of these cells remain incompletely characterized. Previous studies have focused on characterizing these progenitors in the postnatal and adult subventricular zone and on analyzing the cellular and physiological properties of these cells in white and gray matter regions in the forebrain. In the present study, we examine the types of neural progeny generated by NG2 progenitors in the cerebellum by employing genetic fate mapping techniques using inducible Cre–Lox systems in vivo with two different mouse lines, the Plp-Cre-ER^T2/Rosa26-EYFP and Olig2-Cre-ER^T2/Rosa26-EYFP double-transgenic mice. Our data indicate that Olig2/Plp-positive NG2 cells display multipotential properties, primarily give rise to oligodendroglia but, surprisingly, also generate Bergmann glia, which are specialized glial cells in the cerebellum. The NG2+ cells also give rise to astrocytes, but not neurons. In addition, we show that glutamate signaling is involved in distinct NG2+ cell-fate/differentiation pathways and plays a role in the normal development of Bergmann glia. We also show an increase of cerebellar oligodendroglial lineage cells in response to hypoxic–ischemic injury, but the ability of NG2+ cells to give rise to Bergmann glia and astrocytes remains unchanged. Overall, our study reveals a novel Bergmann glia fate of Olig2/Plp-positive NG2 progenitors, demonstrates the differentiation of these progenitors into various functional glial cell types, and provides significant insights into the fate and function of Olig2/Plp-positive progenitor cells in health and disease.     

Severe depletion of mucosal CD4+ T cells in AIDS-free simian immunodeficiency virus-infected sooty mangabeys

HIV-infected humans and SIV-infected rhesus macaques experience a rapid and dramatic loss of mucosal CD4+ T cells that is considered to be a key determinant of AIDS pathogenesis. In this study, we show that nonpathogenic SIV infection of sooty mangabeys (SMs), a natural host species for SIV, is also associated with an early, severe, and persistent depletion of memory CD4+ T cells from the intestinal and respiratory mucosa. Importantly, the kinetics of the loss of mucosal CD4+ T cells in SMs is similar to that of SIVmac239-infected rhesus macaques. Although the nonpathogenic SIV infection of SMs induces the same pattern of mucosal target cell depletion observed during pathogenic HIV/SIV infections, the depletion in SMs occurs in the context of limited local and systemic immune activation and can be reverted if virus replication is suppressed by antiretroviral treatment. These results indicate that a profound depletion of mucosal CD4+ T cells is not sufficient per se to induce loss of mucosal immunity and disease progression during a primate lentiviral infection. We propose that, in the disease-resistant SIV-infected SMs, evolutionary adaptation to both preserve immune function with fewer mucosal CD4+ T cells and attenuate the immune activation that follows acute viral infection protect these animals from progressing to AIDS.     

Sensitive fluorescence polarization technique for rapid screening of alpha-synuclein oligomerization/fibrillization inhibitors

Parkinson's disease (PD) is characterized by the accumulation of fibrillar alpha-synuclein (alpha-Syn) inclusions known as Lewy bodies (LBs) and Lewy neurites. Mutations in the alpha-Syn gene or extra copies thereof cause familial PD or dementia with LBs (DLB) in rare kindreds, but abnormal accumulations of wildtype alpha-Syn also are implicated in the pathogenesis of sporadic PD, the most common movement disorder. Insights into mechanisms underlying alpha-Syn mediated neurodegeneration link alpha-Syn oligomerization and fibrillization to the onset and progression of PD. Thus, inhibiting alpha-Syn oligomer or fibril formation is a compelling target for discovering disease modifying therapies for PD, DLB, and related synucleinopathies. Although amyloid dyes recognize alpha-Syn fibrils, efficient detection of soluble oligomers remains a challenge. Here, we report a novel fluorescence polarization (FP) technique for examining alpha-Syn assembly by monitoring changes in its relative molecular mass during progression of normal alpha-Syn from highly soluble monomers to higher order multimers and thence insoluble amyloid fibrils. We report that FP is more sensitive than conventional amyloid dye methods for the quantification of mature fibrils, and that FP is capable of detecting oligomeric alpha-Syn, allowing for rapid automated screening of potential inhibitors of alpha-Syn oligomerization and fibrillization. Furthermore, FP can be combined with an amyloid dye in a single assay that simultaneously provides two independent biophysical readouts for monitoring alpha-Syn fibrillization. Thus, this FP method holds potential to accelerate discovery of disease modifying therapies for LB PD, DLB, and related neurodegenerative synucleinopathies.     

Maternity length of stay modelling by gamma mixture regression with random effects

Maternity length of stay (LOS) is an important measure of hospital activity, but its empirical distribution is often positively skewed. A two-component gamma mixture regression model has been proposed to analyze the heterogeneous maternity LOS. The problem is that observations collected from the same hospital are often correlated, which can lead to spurious associations and misleading inferences. To account for the inherent correlation, random effects are incorporated within the linear predictors of the two-component gamma mixture regression model. An EM algorithm is developed for the residual maximum quasi-likelihood estimation of the regression coefficients and variance component parameters. The approach enables the correct identification and assessment of risk factors affecting the short-stay and long-stay patient subgroups. In addition, the predicted random effects can provide information on the inter-hospital variations after adjustment for patient characteristics and health provision factors. A simulation study shows that the estimators obtained via the EM algorithm perform well in all the settings considered. Application to a set of maternity LOS data for women having obstetrical delivery with multiple complicating diagnoses is illustrated.     

Effect of agitation on violacein production in Pseudoalteromonas luteoviolacea isolated from a marine sponge

AIMS: Experiments were designed to investigate the effect of agitation on the production of violacein by a marine bacterium Pseudoalteromonas luteoviolacea. METHODS AND RESULTS: A marine sponge-associated bacterium, P. luteoviolacea, was grown at different agitation speeds. Agitation did not have a significant effect on bacterial growth, but had a profound effect on the size of bacterial aggregate. The production of violacein was the highest under stagnant conditions and decreased with the increase of the agitation speed. CONCLUSIONS: Agitation affected the aggregation of bacterial cells, which, in turn, affected violacein production by P. luteoviolacea. SIGNIFICANCE AND IMPACT OF THE STUDY: This study suggests that P. luteoviolacea produced the highest amount of violacein when it was cultured under stagnant conditions.