Syntheses of novel antimycobacterial combinatorial libraries of structurally diverse substituted pyrimidines by three-component solid-phase reactions

A new pyrimidine based scaffold has been developed by three-component solid-phase syntheses. The utility of scaffolds was demonstrated by synthesizing libraries of 80 substituted pyrimidines (a-p), (a-p), 14(a-p), 15(a-p), 16(a-p). Among 80 compounds screened, six compounds, 12i, 13c, 14d, 14e, 14o, and 15d showed in vitro activity against Mycobacterium tuberculosis (MABA) at a concentration of 50 and 25 microg/mL     

Expression of βA3/A1-crystallin in the developing and adult rat eye

Crystallins are very abundant structural proteins of the lens and are also expressed in other tissues. We have previously reported a spontaneous mutation in the rat βA3/A1-crystallin gene, termed Nuc1, which has a novel, complex, ocular phenotype. The current study was undertaken to compare the expression pattern of this gene during eye development in wild type and Nuc1 rats by in situ hybridization (ISH) and immunohistochemistry (IHC). βA3/A1-crystallin expression was first detected in the eyes of both wild type and Nuc1 rats at embryonic (E) day 12.5 in the posterior portion of the lens vesicle, and remained limited to the lens fibers throughout fetal life. After birth, βA3/A1-crystallin expression was also detected in the neural retina (specifically in the astrocytes and ganglion cells) and in the retinal pigmented epithelium (RPE). This suggested that βA3/A1-crystallin is not only a structural protein of the lens, but has cellular function(s) in other ocular tissues. In summary, expression of βA3/A1-crystallin is controlled differentially in various eye tissues with lens being the site of greatest expression. Similar staining patterns, detected by ISH and IHC, in wild type and Nuc1 animals suggest that functional differences in the protein, rather than changes in mRNA/protein level of expression, likely account for developmental abnormalities in Nuc1.     

Wnt/Ca2+ signaling pathway: a brief overview

The non-canonical Wnt/Ca(2+) signaling cascade is less characterized than their canonical counterpart, the Wnt/β-catenin pathway. The non-canonical Wnt signaling pathways are diverse, defined as planer cell polarity pathway, Wnt-RAP1 signaling pathway, Wnt-Ror2 signaling pathway, Wnt-PKA pathway, Wnt-GSK3MT pathway, Wnt-aPKC pathway, Wnt-RYK pathway, Wnt-mTOR pathway, and Wnt/calcium signaling pathway. All these pathways exhibit a considerable degree of overlap between them. The Wnt/Ca(2+) signaling pathway was deciphered as a crucial mediator in development. However, now there is substantial evidence that the signaling cascade is involved in many other molecular phenomena. Many aspects of Wnt/Ca(2+) pathway are yet enigmatic. This review will give a brief overview of the fundamental and evolving concepts of the Wnt/Ca(2+) signaling pathway.     

Increased PTH and 1.25(OH)(2)D levels associated with increased markers of bone turnover following bariatric surgery

The objective of this study was to characterize changes in metabolic bone parameters following bariatric surgery. Seventy-three obese adult patients who underwent either gastric banding (GB), Roux-en-Y gastric bypass (RYGB), or biliopancreatic diversion with duodenal switch (BPD/DS) were followed prospectively for 18 months postoperatively. Changes in the calcium-vitamin D axis (25-hydroxyvitamin D (25OHD), 1,25-dihydroxyvitamin D (1,25(OH)(2)D), calcium, parathyroid hormone (PTH)), markers of bone formation (osteocalcin, bone-specific alkaline phosphatase) and resorption (urinary N-telopeptide (NTx)), as well as bone mineral density (BMD) were assessed at 3-month intervals during this time period. Bariatric surgery resulted in significant and progressive weight loss over 18 months. With supplementation, 25OHD levels increased 65.3% (P < 0.0001) by 3 months, but leveled off and decreased <30 ng/ml by 18 months. PTH initially decreased 21.4% (P = 0.01) at 3 months, but later approached presurgery levels. 1,25(OH)(2)D increased significantly starting at month 12 (50.3% increase from baseline, P = 0.008), and was positively associated with PTH (r = 0.82, P = 0.0001). When stratified by surgery type, median PTH and 1,25(OH)(2)D levels were higher following combined restrictive and malabsorptive operations (RYGB and BPD/DS) compared to GB. Bone formation/resorption markers were increased by 3 months (P < 0.05) and remained elevated through 18 months. Radial BMD decreased 3.5% by month 18, but this change was not significant (P = 0.23). Our findings show that after transient improvement, preoperative vitamin D insufficiency and secondary hyperparathyroidism persisted following surgery despite supplementation. Postoperative secondary hyperparathyroidism was associated with increased 1,25(OH)(2)D levels and increased bone turnover markers.     

Characterization of the biosynthesis, processing and kinetic mechanism of action of the enzyme deficient in mucopolysaccharidosis IIIC

Heparin acetyl-CoA:alpha-glucosaminide N-acetyltransferase (N-acetyltransferase, EC 2.3.1.78) is an integral lysosomal membrane protein containing 11 transmembrane domains, encoded by the HGSNAT gene. Deficiencies of N-acetyltransferase lead to mucopolysaccharidosis IIIC. We demonstrate that contrary to a previous report, the N-acetyltransferase signal peptide is co-translationally cleaved and that this event is required for its intracellular transport to the lysosome. While we confirm that the N-acetyltransferase precursor polypeptide is processed in the lysosome into a small amino-terminal alpha- and a larger ß- chain, we further characterize this event by identifying the mature amino-terminus of each chain. We also demonstrate this processing step(s) is not, as previously reported, needed to produce a functional transferase, i.e., the precursor is active. We next optimize the biochemical assay procedure so that it remains linear as N-acetyltransferase is purified or protein-extracts containing N-acetyltransferase are diluted, by the inclusion of negatively charged lipids. We then use this assay to demonstrate that the purified single N-acetyltransferase protein is both necessary and sufficient to express transferase activity, and that N-acetyltransferase functions as a monomer. Finally, the kinetic mechanism of action of purified N-acetyltransferase was evaluated and found to be a random sequential mechanism involving the formation of a ternary complex with its two substrates; i.e., N-acetyltransferase does not operate through a ping-pong mechanism as previously reported. We confirm this conclusion by demonstrating experimentally that no acetylated enzyme intermediate is formed during the reaction.     

Visual acuity and associated factors. The Central India Eye and Medical Study

Visual acuity is a major parameter for quality of vision and quality of life. Information on visual acuity and its associated factors in rural societies almost untouched by any industrialization is mostly non-available. It was, therefore, the purpose of our study to determine the distribution of visual acuity and its associated factors in a rural population not marked influenced by modern lifestyle. The population-based Central India Eye and Medical Study included 4711 subjects (aged 30+ years), who underwent a detailed ophthalmologic examination including visual acuity measurement. Visual acuity measurements were available for 4706 subjects with a mean age of 49.5±13.4 years (range: 30–100 years). BCVA decreased significantly (P<0.001) from the moderately hyperopic group (0.08±0.15 logMAR) to the emmetropic group (0.16±0.52 logMAR), the moderately myopic group (0.28±0.33 logMAR), the highly hyperopic group (0.66±0.62 logMAR) and finally the highly myopic group (1.32±0.92 logMAR). In multivariate analysis, BCVA was significantly associated with the systemic parameters of lower age (P<0.001), higher level of education (P<0.001), higher body stature (P<0.001) and higher body mass index (P<0.001), and with the ophthalmic parameters of more hyperopic refractive error (spherical equivalent) (P<0.001), shorter axial length (P<0.001), lower degree of nuclear cataract (P<0.001), and lower intraocular pressure (P = 0.006). The results suggest that in the rural population of Central India, major determinants of visual acuity were socioeconomic background, body stature and body mass index, age, refractive error, cataract and intraocular pressure.     

Therapy with sodium stibogluconate in stearylamine-bearing liposomes confers cure against SSG-resistant Leishmania donovani in BALB/c mice

Background

Resistance of Leishmania donovani to pentavalent antimonials, the first-line treatment of visceral leishmaniasis (VL), has become a critical issue worldwide. Second-line and new drugs are also not devoid of limitations. Suitable drug-delivery systems can improve the mode of administration and action of the existing antimonials, thus increasing their clinical life.

Methodology/Principal Findings

We investigated the efficacy of sodium stibogluconate (SSG) in phosphatidylcholine (PC)–stearylamine-bearing liposomes (PC-SA-SSG), PC-cholesterol liposomes (PC-Chol-SSG) and free amphotericin B (AmB) against SSG-resistant L. donovani strains in 8-wk infected BALB/c mice. Animals were sacrificed and parasites in liver, spleen and bone marrow were estimated 4-wk post-treatment by microscopic examination of stamp smears and limiting dilution assay. A set of PC-SA-SSG and AmB treated mice were further studied for protection against reinfection. Serum antibodies and cytokine profiles of ex-vivo cultured splenocytes were determined by ELISA. Uptake of free and liposomal SSG in intracellular amastigotes was determined by atomic absorption spectroscopy. Rhodamine 123 and 5-carboxyfluorescein, known substrates of Pgp and MRP transporter proteins, respectively, were used in free and liposomal forms for efflux studies to estimate intracellular drug retention. Unlike free and PC-Chol-SSG, PC-SA-SSG was effective in curing mice infected with two differentially originated SSG-unresponsive parasite strains at significantly higher levels than AmB. Successful therapy correlated with complete suppression of disease-promoting IL-10 and TGF-β, upregulation of Th1 cytokines and expression of macrophage microbicidal NO. Cure due to elevated accumulation of SSG in intracellular parasites, irrespective of SSG-resistance, occurs as a result of increased drug retention and improved therapy when administered as PC-SA-SSG versus free SSG.

Conclusions/Significance

The design of this single-dose combination therapy with PC-SA-SSG for VL, having reduced toxicity and long-term efficacy, irrespective of SSG-sensitivity may prove promising, not only to overcome SSG-resistance in Leishmania, but also for drugs with similar resistance-related problems in other diseases.     

Enzymatic toxins from snake venom: structural characterization and mechanism of catalysis

Snake venoms are cocktails of enzymes and non-enzymatic proteins used for both the immobilization and digestion of prey. The most common snake venom enzymes include acetylcholinesterases, l-amino acid oxidases, serine proteinases, metalloproteinases and phospholipases A(2) . Higher catalytic efficiency, thermal stability and resistance to proteolysis make these enzymes attractive models for biochemists, enzymologists and structural biologists. Here, we review the structures of these enzymes and describe their structure-based mechanisms of catalysis and inhibition. Some of the enzymes exist as protein complexes in the venom. Thus we also discuss the functional role of non-enzymatic subunits and the pharmacological effects of such protein complexes. The structures of inhibitor-enzyme complexes provide ideal platforms for the design of potent inhibitors which are useful in the development of prototypes and lead compounds with potential therapeutic applications.