Dietary antioxidant curcumin inhibits microtubule assembly through tubulin binding

Curcumin, a component of turmeric, has potent antitumor activity against several tumor types. However, its molecular target and mechanism of antiproliferative activity are not clear. Here, we identified curcumin as a novel antimicrotubule agent. We have examined the effects of curcumin on cellular microtubules and on reconstituted microtubules in vitro. Curcumin inhibited HeLa and MCF-7 cell proliferation in a concentration-dependent manner with IC(50) of 13.8 +/- 0.7 microm and 12 +/- 0.6 microm, respectively. At higher inhibitory concentrations (> 10 microm), curcumin induced significant depolymerization of interphase microtubules and mitotic spindle microtubules of HeLa and MCF-7 cells. However, at low inhibitory concentrations there were minimal effects on cellular microtubules. It disrupted microtubule assembly in vitro, reduced GTPase activity, and induced tubulin aggregation. Curcumin bound to tubulin at a single site with a dissociation constant of 2.4 +/- 0.4 microm and the binding of curcumin to tubulin induced conformational changes in tubulin. Colchicine and podophyllotoxin partly inhibited the binding of curcumin to tubulin, while vinblastine had no effect on the curcumin-tubulin interactions. The data together suggested that curcumin may inhibit cancer cells proliferation by perturbing microtubule assembly dynamics and may be used to develop efficacious curcumin analogues for cancer chemotherapy.     

Role of an ABC Importer in Mycobacterial Drug Resistance

Phosphate specific transporter (Pst) in bacteria is involved in phosphate transport. Pst is a multisubunit system which belongs to the ABC family of transporters. The import function of this transporter is known to be operative at media phosphate concentrations below the millimolar range. However, we found amplification of this transporter in a laboratory generated ciprofloxacin resistant Mycobacterium smegmatis colony (CIP^r) which was grown in a condition when phosphate scavenging function of this operon was inoperative. Our results therefore argue the role of this ABC importer in conferring high level of fluoroquinolone resistance in CIP^r.     

Hexarelin protects rat cardiomyocytes from angiotensin II-induced apoptosis in vitro

Loss of cardiomyocytes by apoptosis is proposed to cause heart failure. Angiotensin II (ANG II), an important neurohormonal factor during heart failure, can induce cardiomyocyte apoptosis. Inasmuch as hexarelin has been reported to have protective effects in this process, we examined whether hexarelin can prevent cardiomyocytes from ANG II-induced cell death. Cultured cardiomyocytes from neonatal rats were stimulated with ANG II. Apoptosis was evaluated using fluorescence microscopy, TdT-mediated dUTP nick-end labeling (TUNEL) method, flow cytometry, DNA laddering, and analysis of cell viability by (3,4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT). It was found that incubation with 0.1 micromol/l ANG II for 48 h increased cardiomyocyte apoptosis. Administration of 0.1 micromol/l hexarelin significantly decreased this ANG II-induced apoptosis and DNA fragmentation and increased myocyte viability. To further investigate the underlying mechanisms, caspase-3 activity assay and mRNA expression of Bax, Bcl-2, and growth hormone secretagogue receptor (GHS-R; the supposed hexarelin binding site) were examined. GHS-R mRNA was abundantly expressed in cardiomyocytes and was upregulated after administration of hexarelin. These results suggest that hexarelin abates cardiomyocytes from ANG II-induced apoptosis possibly via inhibiting the increased caspase-3 activity and Bax expression induced by ANG II and by increasing the expression of Bcl-2, which is depressed by ANG II. Whether the upregulated expression of GHS-R induced by hexarelin is associated with this antiapoptotic effect deserves further investigation.     

An efficient oxidizing reagent for the synthesis of mixed backbone oligonucleotides via the H-phosphonate approach

The mixture of carbon tetrachloride, N-methyl morpholine (NMM), pyridine and water in acetonitrile has been exploited for the oxidation of dinucleoside H-phosphonate diesters to the corresponding phosphates. The system is found to be inert to the phosphoramidate (P-N) and the phosphorothioate (P-S) linkages and has successfully been applied to the solid phase synthesis of mixed-backbone oligonucleotides (MBOs).     

Liquid chromatography-tandem mass spectrometry (LC-MS-MS) method for simultaneous determination of venlafaxine and its active metabolite O-desmethyl venlafaxine in human plasma

A rapid and sensitive liquid chromatography-tandem mass spectrometry (LC-MS-MS) method has been developed and validated for simultaneous quantification of venlafaxine (VEN) and O-desmethyl venlafaxine (ODV) in human plasma. The analytes were extracted from human plasma by using solid-phase extraction (SPE) technique. Escitalopram (ESC) was used as the internal standard. A Betasil C18 column provided chromatographic separation of analytes followed by detection with mass spectrometry. The mass transition ion-pair has been followed as m/z 278.27-->121.11 for VEN, m/z 264.28-->107.10 for ODV and m/z 325.00-->262.00 for ESC. The method involves a solid phase extraction from plasma, simple isocratic chromatography conditions and mass spectrometric detection that enables detection at nanogram levels. The proposed method has been validated with linear range of 3-300 ng/ml for VEN and 6-600 ng/ml for ODV. The intrarun and interrun precision and accuracy values are within 10%. The overall recoveries for VEN and ODV were 95.9 and 81.7%, respectively. Total elution time as low as 3 min only.     

Facile exchange of glycosyl S,S-acetals to their O,O-acetals and preparation of glycofuranosides from acyclic glycosyl S,S-acetals under metal-free reaction conditions in the presence of 1,3-dibromo-5,5-dimethylhydantoin

Exchange of acyclic glycosyl dithioacetals to their O,O-acetals has been achieved by a generalized reaction protocol mediated by 1,3-dibromo-5,5-dimethylhydantoin under mild, metal-free and neutral conditions. This methodology has been extended to the synthesis of alkyl glycofuranosides.     

HClO4-SiO2 catalyzed per-O-acetylation of carbohydrates

An efficient per-O-acetylation of carbohydrates catalyzed by HClO4-SiO2 is reported using a stoichiometric quantity of acetic anhydride avoiding the use of pyridine and excess acetic anhydride under solvent-free conditions.     

Comparison of 16S rRNA gene sequences of genus <Emphasis Type="Italic">Methanobrevibacter</Emphasis>

Background  

The phylogeny of the genus Methanobrevibacter was established almost 25 years ago on the basis of the similarities of the 16S rRNA oligonucleotide catalogs. Since then, many 16S rRNA gene sequences of newly isolated strains or clones representing the genus Methanobrevibacter have been deposited. We tried to reorganize the 16S rRNA gene sequences of this genus and revise the taxonomic affiliation of the isolates and clones representing the genus Methanobrevibacter.     

Chromosome measurements on an XXp+ male

Summary Measurements carried out on an XX male show that there is a significant difference between the lengths of the short arm of the 2 X chromosomes of this patient and that the short arm of the longer X is also significantly different from that of the X chromosomes derived from normal individuals. The difference lies specifically in the size of the terminal band of the short arm. These results are consistent with the X-Y interchange hypothesis of Ferguson-Smith.     

Prevalence and Incidence of Hypoglycaemia in 532,542 People with Type 2 Diabetes on Oral Therapies and Insulin: A Systematic Review and Meta-Analysis of Population Based Studies

Objective

To collate and evaluate the current literature reporting the prevalence and incidence of hypoglycaemia in population based studies of type 2 diabetes.

Research Design and Methods

Medline, Embase and Cochrane were searched up to February 2014 to identify population based studies reporting the proportion of people with type 2 diabetes experiencing hypoglycaemia or rate of events experienced. Two reviewers independently screened studies for eligibility and extracted data for included studies. Random effects meta-analyses were carried out to calculate the prevalence and incidence of hypoglycaemia.

Results

46 studies (n = 532,542) met the inclusion criteria. Prevalence of hypoglycaemia was 45% (95%CI 0.34,0.57) for mild/moderate and 6% (95%CI, 0.05,0.07) for severe. Incidence of hypoglycaemic episodes per person-year for mild/moderate and for severe was 19 (95%CI 0.00, 51.08) and 0.80 (95%CI 0.00,2.15), respectively. Hypoglycaemia was prevalent amongst those on insulin; for mild/moderate episodes the prevalence was 50% and incidence 23 events per person-year, and for severe episodes the prevalence was 21% and incidence 1 event per person-year. For treatment regimes that included a sulphonylurea, mild/moderate prevalence was 30% and incidence 2 events per person-year, and severe prevalence was 5% and incidence 0.01 events per person-year. A similar prevalence of 5% was found for treatment regimes that did not include sulphonylureas.

Conclusions

Current evidence shows hypoglycaemia is considerably prevalent amongst people with type 2 diabetes, particularly for those on insulin, yet still fairly common for other treatment regimens. This highlights the subsequent need for educational interventions and individualisation of therapies to reduce the risk of hypoglycaemia.