Ras membrane targeting is essential for glucose signaling but not for viability in yeast.

Ras proteins are small GTP binding proteins that serve as critical relays in a variety of signal transduction pathways in eukaryotic cells. Like most metazoan Ras proteins, yeast Ras is post-translationally modified by addition of a farnesyl and a palmitoyl moiety, and these modifications are required for targeting the protein to the cytoplasmic face of the plasma membrane and for biological activity of the protein. We have constructed mutants of the yeast (Saccharomyces cerevisiae) Ras that are farnesylated in vivo but are not palmitoylated. These mutant proteins are not localized to the plasma membrane but function in the cell as well as the wild-type protein. Such mutants are viable but fail to induce a transient increase in intracellular cAMP concentration in response to glucose addition, although this deficiency does not yield a marked growth phenotype. These results are consistent with the hypothesis that the essential role of the farnesyl moiety on yeast Ras is to enhance productive interaction between Ras and its essential downstream target, adenylyl cyclase, rather than to localize Ras to the plasma membrane.     

Subtype B and subtype C HIV type 1 recombinants in the northeastern state of Manipur, India

The predominant HIV-1 strain circulating in India is subtype C. However, subtype A and B strains of HIV-1 have also been reported in India. In 1999, the first A/C recombinant strain was reported from Pune in India. Intravenous drug users (IVDUs) from the northeastern region of India have a high HIV-1 seroprevalence. Studies carried out in intravenous drug users in the northeastern region of India have shown that HIV-1 subtype C is the predominant strain infecting IVDUs. Fourteen blood samples were collected from HIV-1-infected individuals from the northeastern region of India and screened by env and gag heteroduplex mobility assays (HMA). Where the env and gag HMA results from a sample yielded different subtypes, sequencing of env and gag PCR products was carried out to confirm the presence of HIV-1 recombinants. Of the 14 samples subtyped, nine samples belonged HIV-1 subtype C (gag C/env C), one to HIV-1 subtype B (gag B/env B), and the remaining were B/C recombinants (gag C/env B). This is the first report of HIV-1 B/C recombinants from India.     

Advanced glycation end products contribute to amyloidosis in Alzheimer disease.

Alzheimer disease (AD) is characterized by deposits of an aggregated 42-amino-acid beta-amyloid peptide (beta AP) in the brain and cerebrovasculature. After a concentration-dependent lag period during in vitro incubations, soluble preparations of synthetic beta AP slowly form fibrillar aggregates that resemble natural amyloid and are measurable by sedimentation and thioflavin T-based fluorescence. Aggregation of soluble beta AP in these in vitro assays is enhanced by addition of small amounts of pre-aggregated beta-amyloid "seed" material. We also have prepared these seeds by using a naturally occurring reaction between glucose and protein amino groups resulting in the formation of advanced "glycosylation" end products (AGEs) which chemically crosslink proteins. AGE-modified beta AP-nucleation seeds further accelerated aggregation of soluble beta AP compared to non-modified "seed" material. Over time, nonenzymatic advanced glycation also results in the gradual accumulation of a set of posttranslational covalent adducts on long-lived proteins in vivo. In a standardized competitive ELISA, plaque fractions of AD brains were found to contain about 3-fold more AGE adducts per mg of protein than preparations from healthy, age-matched controls. These results suggest that the in vivo half-life of beta-amyloid is prolonged in AD, resulting in greater accumulation of AGE modifications which in turn may act to promote accumulation of additional amyloid.     

Efficacy of Withania somnifera chemotypes NMITLI – 101R, 118R and Withaferin A against experimental visceral leishmaniasis

The immunoprophylactic and therapeutic potentials of root extracts of Withania somnifera chemotypes (NMITLI‐118, NMITLI‐101) and pure withanolide–withaferin A was investigated against Leishmania donovani infection in hamsters. The naive animals, fed orally with immunostimulatory doses of chemotypes 101R, 118R (10 and 3 mg/kg) and withaferin A (9 and 3 mg/kg) for five consecutive days and challenged with Leishmania parasites on day 6, were euthanized on days 30 and 45 p.c. for the assessment of parasite clearance, real‐time analysis of mRNAs of Th1/Th2 cytokines (IFN‐γ, IL‐12, TNF‐α, iNOS/IL‐4, IL‐10 and TGF‐β), NO production, reactive oxygen species (ROS) generation, lymphocyte transformation test and antibody responses. By day 45 p.c., there was a significant increase in the mRNA expression of iNOS, IFN‐γ, IL‐12 and TNF‐α but decrease in IL‐4, IL‐10 and TGF‐β, an enhanced Leishmania‐specific LTT response as well as ROS, NO and antileishmanial IgG2 levels in 101R‐treated hamsters followed by 118R‐ and withaferin A‐treated ones, respectively. When these chemotypes were given to L. donovani‐infected hamsters at different doses, there was moderate therapeutic efficacy of chemotype 101R (~50%) at 30 mg/kg × 5 followed by the other two. The results established that the 101R is the most potential chemotype and can be evaluated for combination therapy along with available antileishmanials.     

Yolk-sac–derived macrophages regulate fetal testis vascularization and morphogenesis

Organogenesis of the testis is initiated when expression of Sry in pre-Sertoli cells directs the gonad toward a male-specific fate. The cells in the early bipotential gonad undergo de novo organization to form testis cords that enclose germ cells inside tubules lined by epithelial Sertoli cells. Although Sertoli cells are a driving force in the de novo formation of testis cords, recent studies in mouse showed that reorganization of the vasculature and of interstitial cells also play critical roles in testis cord morphogenesis. However, the mechanism driving reorganization of the vasculature during fetal organogenesis remained unclear. Here we demonstrate that fetal macrophages are associated with nascent gonadal and mesonephric vasculature during the initial phases of testis morphogenesis. Macrophages mediate vascular reorganization and prune errant germ cells and somatic cells after testis architecture is established. We show that gonadal macrophages are derived from primitive yolk-sac hematopoietic progenitors and exhibit hallmarks of M2 activation status, suggestive of angiogenic and tissue remodeling functions. Depletion of macrophages resulted in impaired vascular reorganization and abnormal cord formation. These findings reveal a previously unappreciated role for macrophages in testis morphogenesis and suggest that macrophages are an intermediary between neovascularization and organ architecture during fetal organogenesis.Mammalian testis morphogenesis is a highly orchestrated process involving pre-Sertoli cells, germ cells, interstitial/mesenchymal cells, and vascular endothelial cells (1), providing an ideal model system to study cellular interactions during fetal organ patterning. In the mouse, cells in the XY (male) gonad undergo extensive cellular rearrangements between embryonic day (E) 11.5 and E12.5 that lead to the formation of testis cords, the precursors of seminiferous tubules in the adult organ (2). Pre-Sertoli cells express sex-determining genes, such as sex determining region of chromosome Y (Sry) and sex determining region Y (SRY)-box 9 (Sox9) (3, 4), and traditionally have been considered the main driving force in generating testicular architecture. However, recent evidence from our laboratory and others suggests that endothelial and other interstitial mesenchymal cells also play critical roles in testis morphogenesis (5–8).Mononuclear phagocytes (MPs) represent a diverse subset of the myeloid immune cell lineage which includes macrophages and dendritic cells. MPs play diverse roles in developmental and disease contexts (9, 10), likely acting through their control of vessel anastomosis, clearing of apoptotic cells and other cellular debris, secretion of cytokines and growth factors, and modulation of extracellular matrix (9, 11). MPs are nearly ubiquitous in adult organs throughout the body and are involved in the morphogenesis of multiple tissues, such as bone, mammary gland ducts, pancreatic islets, and eye vasculature (12–15). However, almost all these processes are postnatal tissue-remodeling events.The origin and function of MPs during fetal organogenesis is poorly understood. Traditional models assumed that hematopoietic stem cells (HSCs) differentiate into monocytes, which circulate through peripheral blood and subsequently are recruited to target tissues via local secretion of cytokines, leading to their differentiation into monocyte-derived lineages, e.g., granulocytes, dendritic cells, or macrophages (reviewed in ref. 10). Definitive hematopoiesis (and the appearance of HSCs) occurs initially in the yolk sac, placenta, and aorta-gonad-mesonephros region (AGM) at different time points between E8.5 and E10.5. HSCs populate the fetal liver shortly thereafter (E11.5–E13.5), before the establishment of the bone marrow. However, “primitive” hematopoiesis, originating from unique yolk-sac–derived progenitor cells, takes place at around E7.5, before definitive hematopoiesis, and gives rise to hematopoietic cell types, including erythrocytes and macrophages, that migrate through the yolk-sac vasculature to colonize the fetus (16). Yolk-sac–derived primitive macrophages can contribute to adult hematopoiesis and adult cell types (17–19). In particular, lineage-tracing analyses showed that adult microglia (brain-specific macrophages) are derived exclusively from primitive yolk-sac precursors (17). Yolk-sac–derived macrophages are distinct from HSC-derived macrophages: Yolk-sac–derived macrophages are F4/80-bright, CD11b-dim, and myeloblastosis oncogene (Myb)- and FMS-like tyrosine kinase 3 (Flt3)-independent, whereas HSC-derived macrophages are F4/80-dim, CD11b-bright, and Myb- and Flt3-dependent (19). It is likely that the distinct origins of these cells impart unique identities and functions.In the postnatal and adult testis, macrophages make up a large portion of the interstitial compartment (20) and are important for Leydig cell development and steroidogenic function (21, 22). However, macrophages have not been detected or functionally characterized during fetal testis morphogenesis. We show that yolk-sac–derived macrophages are the only major myeloid cell type in the fetal gonad during morphogenesis of the testis. These macrophages interacted with multiple cell types but were prominent near developing vasculature. Specific depletion of macrophages resulted in significant vascular and architectural abnormalities in the fetal testis. These studies uncover a previously unidentified role for gonadal–mesonephric macrophages in testis morphogenesis, consistent with a broader role for macrophages in fetal development and organogenesis.     

Triphala inhibits alpha-synuclein fibrillization and their interaction study by NMR provides insights into the self-association of the protein

The process of assembly and accumulation of the intrinsically disordered protein (IDP), alpha-synuclein (αSyn) into amyloid fibrils is a pathogenic process leading to several neurodegenerative disorders such as Parkinson''s disease, multiple system atrophy and others. Although several molecules are known to inhibit αSyn fibrillization, the mechanism of inhibition is just beginning to emerge. Here, we report the inhibition of fibrillization of αSyn by Triphala, a herbal preparation in the traditional Indian medical system of Ayurveda. Triphala was found to be a rich source of polyphenols which are known to act as amyloid inhibitors. ThT fluorescence and TEM studies showed that Triphala inhibited the fibrillization of αSyn. However, it was observed that Triphala does not disaggregate preformed αSyn fibrils. Further, native-PAGE showed that Triphala reduces the propensity of αSyn to oligomerize during the lag phase of fibrillization. Our NMR results showed that certain stretches of residues in the N-terminal and NAC regions of αSyn play an anchor role in the self-association process of the protein, thereby providing mechanistic insights into the early events during αSyn fibrillization.

Triphala inhibits αSyn self-association by interacting with anchoring regions which are responsible for αSyn oligomerization.     

A diabetes perception study among rural and urban individuals of West Bengal,India: are we ready for the pandemic?

International Journal of Diabetes in Developing Countries - Type 2 diabetes is a pandemic in India, yet studies regarding knowledge, attitude, and practices in diabetes in various Indian...     

Decreased white matter integrity in fronto-occipital fasciculus bundles: Relation to visual information processing in alcohol-dependent subjects

Chronic alcohol abuse is characterized by impaired cognitive abilities with a more severe deficit in visual than in verbal functions. Neuropathologically, it is associated with widespread brain structural compromise marked by gray matter shrinkage, ventricular enlargement, and white matter degradation. The present study sought to increase current understanding of the impairment of visual processing abilities in alcohol-dependent subjects, and its correlation with white matter microstructural alterations, using diffusion tensor imaging (DTI). To that end, a DTI study was carried out on 35 alcohol-dependent subjects and 30 healthy male control subjects. Neuropsychological tests were assessed for visual processing skills and deficits were reported as raw dysfunction scores (rDyS). Reduced FA (fractional anisotropy) and increased MD (mean diffusivity) were observed bilaterally in inferior and superior fronto-occipital fasciculus (FOF) fiber bundles. A significant inverse correlation in rDyS and FA values was observed in these fiber tracts whereas a positive correlation of these scores was found with the MD values. Our results suggest that FOF fiber bundles linking the frontal lobe to occipital lobe might be related to visual processing skills. This is the first report of an alteration of the white matter microstructure of FOF fiber bundles that might have functional consequences for visual processing in alcohol-dependent subjects who exhibit no neurological complications.