Structure, biochemistry, and inhibition of essential 4'-phosphopantetheinyl transferases from two species of Mycobacteria

4′-Phosphopantetheinyl transferases (PPTase) post-translationally modify carrier proteins with a phosphopantetheine moiety, an essential reaction in all three domains of life. In the bacterial genus Mycobacteria, the Sfp-type PPTase activates pathways necessary for the biosynthesis of cell wall components and small molecule virulence factors. We solved the X-ray crystal structures and biochemically characterized the Sfp-type PPTases from two of the most prevalent Mycobacterial pathogens, PptT of M. tuberculosis and MuPPT of M. ulcerans. Structural analyses reveal significant differences in cofactor binding and active site composition when compared to previously characterized Sfp-type PPTases. Functional analyses including the efficacy of Sfp-type PPTase-specific inhibitors also suggest that the Mycobacterial Sfp-type PPTases can serve as therapeutic targets against Mycobacterial infections.

Prevalence and correlates of alcohol use and subsequent sexual activity among adult males in a rural community of ethnic minorities in Yunnan Province, China

This community-based cross-sectional study examined alcohol use and HIV risks among a sample of predominantly ethnic males in Yunnan Province, China. Information about alcohol use, sexual behavior, sex after drinking, and HIV infection was collected using face-to-face interviews and blood testing. Out of 497 potential male participants, 382 males agreed to participate in this study. Of these males, 70% were ethnic minorities, 74.1% were currently married, 95.5% were sexually experienced, 27.5% had used drugs, and 6% were HIV-infected. Over 81% were current drinkers and 55.7% started drinking before the age of 18. Among current drinkers, 44.5% drank daily and 31.9% had drunk heavily in the past 30 days. Baijiu (a Chinese liquor distilled from sorghum with an ethanol content of at least 40%) was the preferred drink of choice. Excessive alcohol use was associated with being an ethnic Jingpo (OR = 1.96), being a smoker (OR = 2.09) and having multiple lifetime sex partners (OR = 1.55). Over 21% reported having ever engaged in sex after drinking. Those who were aged 26 to 35 (OR = 3.80), started drinking before age 18 (OR = 2.14), who were heavy drinkers (OR = 1.99), or who had ever used drugs (OR = 2.00) were more likely to have ever engaged in sex after drinking. Health education programs for alcohol abuse and unwanted outcomes, particularly the risk of HIV, are urgently needed for ethnic males in Yunnan.

Dual-frequency High Intensity Focused Ultrasound (HIFU) Accelerating Therapy

By cutting a spherical focused transducer into two coaxial and confocal transducer elements, a confocal complex transducer used in dual-frequency HIFU system was obtained. The lesion induced by dual-frequency HIFU in freshly excised porcine livers were obviously larger than that induced by conventional single-frequency HIFU at the same exposure conditions. The experiment results have also shown that injecting ultrasound contrast agents to the tissue or selecting appropriate difference frequency could further improve the lesioning effect. The dual-frequency HIFU would bring a new approach to accelerate ablating large tumor with HIFU and also provide a new method to miniaturize the conventional HIFU apparatus.

Modulation of ascorbic acid-induced DNA cleavage by polyamide: cleavage manner, kinetics and mechanism

Manipulation of DNA presents a great interest in biotechnology and therapeutics. The molecules that damage DNA selectively offer new prospects for controlled manipulation of DNA. The conjugations of DNA-code reading molecules such as polyamides to reagents that induce DNA damages provide an approach to reach this goal. In this work, a new compound which contained polyamide and ascorbic acid conjugated by flexible linker (polyamide-Vc), was successfully synthesized, characterized, and evaluated as DNA cleavage agent, compared with that by using ascorbic acid molecule. The kinetics data showed that polyamide-Vc successfully promoted the cleavage of plasmid DNA, with k(max) of 0.314 h(-1) and K(d) of 0.105 mM. The evaluation of DNA linearization elicited that the activity of cleaving double-strand in the supercoiled pUC18 plasmid DNA by polyamide-Vc was enhanced remarkably, achieving n1/n2 ratio of 13.9 at 1.2 mM for 1 h. The introduction of polyamide to Vc could also partially weaken the inhibition of hydrogen radical to double-strand cleavage process because of its good binding activity to DNA. We anticipate that this work could provide a method for improving the efficiency of double-strand cleavage, especially to oxidative cleavage agents.

The situation of sanitary systems in rural areas in the Miyun catchment, China

The Miyun Reservoir provides most of Beijing's drinking water. Despite its importance, the Miyun reservoir suffers from decreasing water quality caused by uncontrolled wastewater discharges, inadequate land use and over fertilization, which increase the pressure on soil and water resources. The major pollutants are nitrogen and phosphorus which emanate to some extent from untreated sewage. So far there is little data about the existing wastewater quantity and quality in rural settlements in northern China. This study was conducted in typical villages situated along upstream rivers in the catchment of the Miyun Reservoir. The main objective was to determine the current situation and efficiency of the wastewater treatment system in rural settlements.

Experimental study on the atlanto-axial joint and related structures with regional anatomy and medical imaging

OBJECTIVE

To evaluate the anatomy and medical imaging characteristics in a study observing the atlanto-axial joint (AAJ) and related structures.

METHODS

Eight cadaveric specimens of the AAJ segment were studied with both anatomical and imaging methods. The vertebral arteries of the AAJ segment (VA-A), the first and second cervical nerves (CN1, CN2) and synovial fold (SF) of the AAJ were observed and measured.

RESULT

After extending from the vertebral canal, the CN1 goes between the posterior arch of the atlas and VA-A, and the CN2 passes between the posterior arch of the atlas and axis, and is posterior to VA-A. Among the eight cases, six were found in the SF in the central anterior AAJ and five in lateral. The vertebral arteries of the AAJ segment go along the AAJ with four curves, of which the second and fourth are away from the bone structure of the AAJ. The distance from CN1, CN2 to VA-A and that from the second, fourth curve of VA-A to AAJ is 0.0-2.2 mm, 0.0-3.6 mm and 0.0-4.8 mm, 2.0-7.9 mm respectively. There is no significant difference between the measurements made anatomically and those by the imaging method (p > 0.05).

CONCLUSION

The anatomical method has advantages in observing the CN and SF, while the imaging method shows clearly and directly the VA-A and AAJ. Both are mutually complementary with consistent measurements. The combined use of the two provides a new way to study the complicated anatomy in this region.

Nitric oxide-releasing nanoparticle combination therapy to overcome drug resistance in platinum-resistant breast cancers

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Background: The most successful cancer chemotherapy regimens usually involve the administration of multiple cytotoxic agents simultaneously. Because different chemotherapies may have different mechanisms of action; it is difficult for cancer cells to become resistant to combination therapy. Recent investigations have discovered that nitric oxide (NO) may be involved in the reversal of cisplatin (CDDP) resistance in chemotherapy. Therefore, we sought to develop a combination regimen involving a NO-releasing prodrug (NO1) and cisplatin for the treatment of breast cancer.

Methods: The prodrug NO1 was synthesized to be localized in tumor cells and to release nitric oxide over 10 hours. The antiproliferative activity of NO1 was determined in human breast cancer cell line, MDA-MB-468LN. To evaluate the effectiveness of the CDDP/NO combination regimen, platinum-resistant MDA-MB-468LN cells were treated with either cisplatin alone ([CDDP]=0.01, 0.02 or 0.03 mM) or the CDDP/NO combination ([CDDP]=0.01, 0.02 or 0.03 mM; [NO1]=0.02 mM). The cell viability was determined 48 hours post-treatment using a live/dead trypan blue exclusion assay.

Results: The toxicity to breast cancer cells was higher than JS-K, a systemic NO agent currently in preclinical development. (NO1: IC50=26µM; JS-K: IC50=42 µM). In addition, NO1 had a long sustained release of nitric oxide, approximately one fold longer than JS-K (NO1: t1/2=6 h; JS-K: t1/2=3 h). The combination treatments resulted in 6.6-, 6.9- and 7.5-fold increase in cell death compared to cisplatin treatment alone at cisplatin concentrations of 0.01, 0.02 and 0.03 mM, respectively. A subsequent study in a murine xenograft of head and neck cancer found NO-1 conjugated to nanoparticles increased survival a mean of 10 weeks compared to controls (p<0.0001).

Conclusions: Nitric oxide prodrug NO-1 and nanoparticles of it have high anticancer activity in vivo and they can reverse platinum resistance in vitro. Ongoing studies are examining the safety and efficacy of CDDP/NO combination therapy in mouse xenografts of human breast cancer.

Impact of prior seasonal influenza vaccination and infection on pandemic A (H1N1) influenza virus replication in ferrets

Early epidemiologic and serologic studies have suggested pre-existing immunity to the pandemic A (H1N1) 2009 influenza virus (H1N1pdm) may be altering its morbidity and mortality in humans. To determine the role that contemporary seasonal H1N1 virus infection or trivalent inactivated vaccine (TIV) might be playing in this immunity we conducted a vaccination-challenge study in ferrets. Vaccination with TIV was unable to alter subsequent morbidity or contact transmission in ferrets following challenge with H1N1pdm. Conversely, prior infection with the contemporary seasonal H1N1 strain altered morbidity, but not transmission, of H1N1pdm despite the detection of only minimal levels of cross reactive antibodies.

Disclosure of HIV-positive serostatus to sexual partners and associated factors in southern China

In light of an increased push for disclosure of HIV-positive serostatus to sexual partners (partner disclosure, PD) in China as reflected by national and local policies, the objective of this study was to determine the proportion and evaluate associated factors of PD among people living with HIV/AIDS (PLWHA) in HIV/AIDS high-risk areas in southern China. Of the 946 HIV-positive individuals, the proportion of those who disclosed positive serostatus results to their sexual partners was 90.2% (625/693). Variables independently associated with non-disclosure included testing in Guangxi province (adjusted relative ratio [ARR] = 0.33), becoming infected with HIV via injecting drug use (IDU) transmission (ARR = 0.32), having not reported discussing disclosure with health department staff during post-test counselling (ARR = 0.41) and having a sexual relationship of ≤2 years' duration (ARR = 0.31). This study also identified a relatively larger differential between the proportion of disclosure to regular partners and the proportion of disclosure to casual partners (94.8% versus 13.0%) in comparison with other studies. Findings from this study may aid policies for future consideration.

Defects of synaptic vesicle turnover at excitatory and inhibitory synapses in Niemann-Pick C1-deficient neurons

Niemann-Pick disease type C (NPC) is a progressive neurodegenerative disorder characterized by accumulation of free cholesterol in late endosomes/lysosomes. The pathological basis for the disease is poorly understood. In the present study, electrophysiological and fluorescent dye studies were applied to examine neuron-specific functions of Niemann-Pick disease type C1 (NPC1) and to determine whether excitatory and inhibitory synapses are differentially impaired by NPC1 deficiency. Densities of spines and postsynaptic receptor clusters were not affected by NPC1 deficiency over the period examined. However, drastic defects on exocytosis were found both in glutamatergic and GABAergic synapses. The defects were caused in part by a delay in the time required for replacement of excytosed vesicles with new fusion-competent ones. Moreover, we found that the delay of synaptic vesicle turnover was longer in inhibitory synapses (>3 s) than in excitatory synapses (<0.2 s). These defects may be early indicators, and could provide a potential explanation for key features of the disease, such as dystonia and seizures.

Heritable and non-genetic factors as variables of pharmacologic phenotypes in lymphoblastoid cell lines

Publicly available genetic and expression data on lymphoblastoid cell lines (LCLs) make them a unique resource for understanding the genetic underpinnings of pharmacological outcomes and disease. LCLs have been used for pharmacogenomic discovery and validation of clinical findings associated with drug response. However, variation in cellular growth rate, baseline Epstein-Barr virus (EBV) copy number and ATP levels can all be confounders in such studies. Our objective is to better define confounding variables that affect pharmacological end points in LCLs. To this end, we evaluated the effect of these three variables on drug-induced cytotoxicity in LCLs. The drugs evaluated included daunorubicin, etoposide, carboplatin, cisplatin, cytarabine, pemetrexed, 5'-deoxyfluorouridine, vorinostat, methotrexate, 6-mercaptopurine, and 5-fluorouracil. Baseline ATP or EBV copy number were not significantly correlated with cellular growth rate or drug-induced cytotoxicity. In contrast, cellular growth rate and drug-induced cytotoxicity were significantly, directly related for all drugs except vorinostat. Importantly, cellular growth rate is under appreciable genetic influence (h²=0.30-0.39) with five suggestive linkage regions across the genome. Not surprisingly, a percentage of SNPs that significantly associate with drug-induced cytotoxicity also associate with cellular growth rate (P ≤ 0.0001). Studies using LCLs for pharmacologic outcomes should therefore consider that a portion of the genetic variation explaining drug-induced cytotoxicity is mediated via heritable effects on growth rate.

The Pirh2-keratin 8/18 interaction modulates the cellular distribution of mitochondria and UV-induced apoptosis

Intermediate filaments (IFs) provide crucial structural support in higher eukaryotic cells. Accumulating evidences show that IFs also participate in various cellular activities including stress responses, cell growth, cell death and cell migration through dynamic interactions with various non-structure proteins. Here we report the identification of Pirh2, a RING-H2-type ubiquitin E3 ligase, as a novel binding partner of the cytoplasmic IF proteins keratin 8/18 (K8/18). Phosphorylation of either Pirh2 or K8/18 affects their association. Although Pirh2 was not found to influence the stability of K8/18, it displayed an unexpected role in regulating the organization of the network of K8/18 keratin filaments. Disruption of Pirh2-K8/K18 interaction by either UV irradiation or knockdown with Pirh2 or K18 led to the aggregation of K8/18 keratin filaments. It further induced mitochondrial redistribution, and this process is likely through a microtubule-mediated pathway. The abnormal localization of mitochondria in Pirh2-knockdown cells may partially account for its increased cell sensitivity to UV-induced apoptosis, probably through enhancing the release of pro-apoptotic proteins, such as cytochrome c and Smac/DIABLO to the cytosol. Overall, our data reveal the novel role of the Pirh2-K8/18 complex in governing the distribution of mitochondria.

Association of HLA genes with ankylosing spondylitis in Han population of eastern China

Ankylosing spondylitis (AS) is a chronic inflammatory disorder with a multifactorial genetic basis. HLA-B27 was reported with the greatest susceptibility to AS but did not act alone. The aim of this study was to search for other gene(s) associated with AS independently of HLA-B27 using 13 microsatellite markers spanning 1.5 Mb from locus TAP1 to HLA-Cw and a single-nucleotide polymorphism marker within NFkappaBIL1 gene promoter. Genotyping for microsatellites was performed in 175 AS patients of eastern Chinese and 219 ethnically matched healthy controls using polymerase chain reaction with fluorescence-labelled primers, whereas the SNP marker was genotyped by direct DNA sequencing. Allele as well as haplotype frequencies were compared between cases and controls, and a linkage disequilibrium analysis was performed to estimate the LD relationship between the candidate regions. The frequencies of alleles D6S2811*128, STR_MICA*A5.1 and D6S2672*109, as well as haplotypes D6S2811*128-D6S2927*213-D6S2810*340, D6S2927* 221-D6S2810*350-MICA*A5.1, and D6S2810*350-MICA*A5.1-D6S2800* 136 were significantly increased in B27-positive AS patients when compared with B27-positive controls. The results indicated that there may be other gene(s) within the HLA region, especially around locus HLA-B or HLA-Cw, with susceptibility to AS independently of HLA-B27.

Living environment and schooling of children with HIV-infected parents in southwest China

A cross-sectional household survey was conducted in Longchuan County, China, to study the lives of children with HIV-infected parents. Registered HIV-infected drug users and their households were approached and information about the living environment of children < or =15 years of age was collected. Of the 266 households interviewed, there were 213 children < or =15 years old. Forty percent of the children had lost at least one parent. Most of the children resided in a household with low economic status and a high dependency ratio. One-half of the children experienced discordant family relations, family anxiety and shame. Compared to orphans, non-orphans and their families were less likely to receive social support from the community. Orphans and older children were less likely to attend school and more likely to be truant if enrolled in school. Findings in the current study suggest that many children whose parents are infected with HIV or have died from HIV are living in stressful environments with minimal support from the community. Efforts should be taken to provide support and supervision to these children.