Risk factors and outcome for colistin-resistant Acinetobacter nosocomialis bacteraemia in patients without previous colistin exposure

The clinical characteristics of patients with colistin-resistant Acinetobacter baumannii bacteraemia have been documented, but those of patients with bacteraemia caused by other Acinetobacter species remain unknown. Previous exposure to colistin has been shown to be associated with the emergence of colistin resistance, but may be not the only predisposing factor. In the current study, we highlight the risk and outcome of patients without previous exposure to colistin who acquired colistin-resistant Acinetobacter nosocomialis (ColRAN) bacteraemia. This 11-year single-centre retrospective study analysed 58 patients with ColRAN bacteraemia and 213 patients with colistin-susceptible A. nosocomialis (ColSAN) bacteraemia. Antimicrobial susceptibilities were determined with an agar dilution method. The clonal relationship of ColRAN isolates was determined with pulsed-field gel electrophoresis. A conjugation mating-out assay was conducted to delineate the potential transfer of colistin resistance genes. Multivariable analysis was performed to evaluate the risk factors for ColRAN bacteraemia. Chronic obstructive pulmonary disease (COPD) was independently associated with ColRAN bacteraemia (OR 3.04; 95% CI 1.45-6.37; p 0.003). Patients with ColRAN bacteraemia had higher APACHE II scores, but the two groups showed no significant differences in 14-day mortality (10.3% vs. 10.3%) or 28-day mortality (15.5% vs. 15.0%). ColRAN isolates had greater resistance than ColSAN isolates to all antimicrobial agents except for ciprofloxacin (0% vs. 6.6%). There were 16 different ColRAN pulsotypes, and two major clones were found. Colistin resistance did not transfer to colistin-susceptible A. baumannii or A. nosocomialis. These results show that COPD is an independent risk factor for acquisition of ColRAN bacteraemia. The mortality rates were similar between patients with ColRAN and ColSAN bacteraemia.

Cytotoxic effects of MgO nanoparticles on human umbilical vein endothelial cells in vitro

The MgO nanoparticles are widely used in many fields. However, the toxicity of these nanoparticles to cells and organs remains fairly undiscovered. In this study, the cytotoxicity of MgO nanoparticles on human umbilical vein endothelial cells (HUVECs) in vitro was examined. The morphology and size of MgO nanoparticles were analysed by the transmission electron microscope (TEM) and nanoparticle size analyser. MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2 h-tetrazolium bromide) assay, 4',6-diamidino-2-phenylindole (DAPI) staining analysis, NO release and total antioxidation competence (T-AOC) assay were used to evaluate the cytotoxicity of MgO nanoparticles. The results showed that most MgO nanoparticles were spherical with agglomerated state and the diameter of single particle was about 100 nm. Meanwhile, low concentration (below 200 [micro sign]g/ml) of MgO nanoparticles suspension showed no cytotoxicity by MTT assay. However, once the concentration of MgO nanoparticles was higher than 500 [micro sign]g/ml, the relative growth rate was lower than the control. The DAPI staining analysis results showed no significant difference of the cells morphology between the groups with or without MgO nanoparticles. In addition, the MgO nanoparticles significantly enhanced the NO release and T-AOC content of the HUVECs. The testing results indicated that low concentration of MgO nanoparticles exhibited non-cytotoxicity.

SIRT1 RNAi knockdown induces apoptosis and senescence, inhibits invasion and enhances chemosensitivity in pancreatic cancer cells

The NAD(+)-dependent deacetylase, sirtuin 1 (SIRT1), has been recently been suspected to have a role in tumorigenesis. We investigated the expression of SIRT1 in pancreatic cancer and the effect of SIRT1-targeted RNA interference (RNAi) on cell proliferation and tumor formation in a pancreatic cancer cell line, PANC1. The expression of SIRT1 was investigated in 49 specimens of pancreatic cancer and adjacent normal pancreatic tissues. SIRT1 was overexpressed in pancreatic cancer tissues at both the mRNA and protein levels, with increased SIRT1 positivity associated with tumors from patients over 60 years old, tumors larger than 4 cm, higher TNM (extent of tumor (T), the extent of spread to lymph nodes (N), and presence of distant metastasis (M)) stage or the presence of lymph node or hepatic metastases. The PANC-1 was stably transfected with a SIRT1 small hairpin RNA (shRNA) expression plasmid and compared with untransfected and PANC-1-negative RNAi cells. Proliferation of PANC-1-SIRT1-RNAi cells was significantly reduced, accompanied by increased rates of apoptosis, G1 arrest and senescence. Furthermore, FOXO3a expression was markedly upregulated in PANC-1-SIRT1-RNAi cells, but no significant difference in p53 expression was observed. The invasive ability of PANC-1-SIRT1-RNAi cells was markedly reduced in vitro, which was linked to increased E-cadherin and reduced-MMP expression. Additionally, PANC-1-SIRT1-RNAi cells had a significantly reduced capacity to form tumors in vivo compared with untransfected and PANC-1-negative RNAi cells. These results suggest that SIRT1 may promote cell proliferation and tumor formation in pancreatic cancer, and downregulation of SIRT1 using shRNA could provide a novel therapeutic treatment.

A genetic linkage map for the ectomycorrhizal fungus Laccaria bicolor and its alignment to the whole-genome sequence assemblies

A genetic linkage map for the ectomycorrhizal basidiomycete Laccaria bicolor was constructed from 45 sib-homokaryotic haploid mycelial lines derived from the parental S238N strain progeny. For map construction, 294 simple sequence repeats (SSRs), single-nucleotide polymorphisms (SNPs), amplified fragment length polymorphisms (AFLPs) and random amplified polymorphic DNA (RAPD) markers were employed to identify and assay loci that segregated in backcross configuration. Using SNP, RAPD and SSR sequences, the L. bicolor whole-genome sequence (WGS) assemblies were aligned onto the linkage groups. A total of 37.36 Mbp of the assembled sequences was aligned to 13 linkage groups. Most mapped genetic markers used in alignment were colinear with the sequence assemblies, indicating that both the genetic map and sequence assemblies achieved high fidelity. The resulting matrix of recombination rates between all pairs of loci was used to construct an integrated linkage map using JoinMap. The final map consisted of 13 linkage groups spanning 812 centiMorgans (cM) at an average distance of 2.76 cM between markers (range 1.9-17 cM). The WGS and the present linkage map represent an initial step towards the identification and cloning of quantitative trait loci associated with development and functioning of the ectomycorrhizal symbiosis.

A dense linkage map of hybrid cottonwood (Populus fremontii × P. angustifolia) contributes to long-term ecological research and comparison mapping in a model forest tree

Cottonwoods are foundation riparian species, and hybridization among species is known to produce ecological effects at levels higher than the population, including effects on dependent species, communities and ecosystems. Because these patterns result from increased genetic variation in key cottonwood traits, novel applications of genetic tools (for example, QTL mapping) could be used to place broad-scale ecological research into a genomic perspective. In addition, linkage maps have been produced for numerous species within the genus, and, coupled with the recent publication of the Populus genome sequence, these maps present a unique opportunity for genome comparisons in a model system. Here, we conducted linkage analyses in order to (1) create a platform for QTL and candidate gene studies of ecologically important traits, (2) create a framework for chromosomal-scale perspectives of introgression in a natural population, and (3) enhance genome-wide comparisons using two previously unmapped species. We produced 246 backcross mapping (BC(1)) progeny by crossing a naturally occurring F(1) hybrid (Populus fremontii x P. angustifolia) to a pure P. angustifolia from the same population. Linkage analysis resulted in a dense linkage map of 541 AFLP and 111 SSR markers distributed across 19 linkage groups. These results compared favorably with other Populus linkage studies, and addition of SSR loci from the poplar genome project provided coarse alignment with the genome sequence. Preliminary applications of the data suggest that our map represents a useful framework for applying genomic research to ecological questions in a well-studied system, and has enhanced genome-wide comparisons in a model tree.

The genome of black cottonwood, Populus trichocarpa (Torr. & Gray)

We report the draft genome of the black cottonwood tree, Populus trichocarpa. Integration of shotgun sequence assembly with genetic mapping enabled chromosome-scale reconstruction of the genome. More than 45,000 putative protein-coding genes were identified. Analysis of the assembled genome revealed a whole-genome duplication event; about 8000 pairs of duplicated genes from that event survived in the Populus genome. A second, older duplication event is indistinguishably coincident with the divergence of the Populus and Arabidopsis lineages. Nucleotide substitution, tandem gene duplication, and gross chromosomal rearrangement appear to proceed substantially more slowly in Populus than in Arabidopsis. Populus has more protein-coding genes than Arabidopsis, ranging on average from 1.4 to 1.6 putative Populus homologs for each Arabidopsis gene. However, the relative frequency of protein domains in the two genomes is similar. Overrepresented exceptions in Populus include genes associated with lignocellulosic wall biosynthesis, meristem development, disease resistance, and metabolite transport.

Scalable production of embryonic stem cell-derived cardiomyocytes

Cardiomyocyte transplantation could offer a new approach to replace scarred, nonfunctional myocardium in a diseased heart. Clinical application of this approach would require the ability to generate large numbers of donor cells. The purpose of this study was to develop a scalable, robust, and reproducible process to derive purified cardiomyocytes from genetically engineered embryonic stem (ES) cells. ES cells transfected with a fusion gene consisting of the alpha-cardiac myosin heavy chain (MHC) promoter driving the aminoglycoside phosphotransferase (neomycin resistance) gene were used for cardiomyocyte enrichment. The transfected cells were aggregated into embyroid bodies (EBs), inoculated into stirred suspension cultures, and differentiated for 9 days before selection of cardiomyocytes by the addition of G418 with or without retinoic acid (RA). Throughout the culture period, EB and viable cell numbers were measured. In addition, flow cytometric analysis was performed to monitor sarcomeric myosin (a marker for cardiomyocytes) and Oct-4 (a marker for undifferentiated ES cells) expression. Enrichment of cardiomyocytes was achieved in cultures treated with either G418 and retinoic acid (RA) or with G418 alone. Eighteen days after differentiation, G418-selected flasks treated with RA contained approximately twice as many cells as the nontreated flasks, as well as undetectable levels of Oct-4 expression, suggesting that RA may promote cardiac differentiation and/or survival. Immunohistological and electron microscopic analysis showed that the harvested cardiomyocytes displayed many features characteristic of native cardiomyocytes. Our results demonstrate the feasibility of large-scale production of viable, ES cell-derived cardiomyocytes for tissue engineering and/or implantation, an approach that should be transferable to other ES cell derived lineages, as well as to adult stem cells with in vitro cardiomyogenic activity.

A likelihood approach for mapping growth trajectories using dominant markers in a phase-unknown full-sib family

Dominant markers have been commonly used in mapping quantitative trait loci (QTLs) in outcrossing species, in which not much prior genome information is available. But the dominant nature of these markers may lead to reduced QTL mapping precision and power. A new statistical method is proposed to incorporate growth laws into a QTL mapping framework, under which the use of the efficiency of dominant markers can be increased. This new method can be used to identify specific QTLs affecting differentiation in growth trajectories, and further estimate the timing of a QTL to turn on, or turn off, affecting growth during the entire ontogeny of a species. Using this method based on dominant markers we have successfully mapped a QTL for stem height growth trajectories to a linkage group in a forest tree. The implications of this method for the understanding of the genetic architecture of growth using dominant markers are discussed.

[Histopathological changes of prostate cancer after castration therapy and correlative factors]

OBJECTIVE

To study the histopathological changes of prostate cancer after castration therapy among Chinese and correlative factors.

METHODS

Needle biopsy specimens and prostatectomy specimens were obtained from 17 cases of prostate cancer and examined by light microscopy and image analysis system.

RESULTS

Glandular atrophy, cytoplasmic vacuolization, nuclear pyknosis, and relative increase of stroma could be seen after orchectomy. There was a close correlation between atrophy of neoplastic tissue in prostate gland and patients' age (P < 0.05). The atrophy of neoplastic tissue in prostate gland was not correlated with the serum PSA, tumor staging and grading before castration therapy (P > 0.05).

CONCLUSION

Castration is effective for treatment of prostate cancer, especially among the elderly patients. It is important for pathologists to recognize the histopathological changes in the prostectomy specimens made untypical by castration.

Preliminary interspecific genetic maps of the populus genome constructed from RAPD markers

We have constructed RAPD-based linkage maps for an interspecific cross between two species of the genus Populus (P. adenopoda and P. alba), based on a double pseudo-test-cross strategy. Of a total of 360 polymorphic fragments scored, 290 showed a test-cross configuration, corresponding to DNA polymorphisms heterozygous in one parent and null in the other. In the female parent, P. adenopoda, 82 markers were grouped in 19 different linkage groups (553 cM), whereas in the male parent P. alba, 197 markers established a much more complete framework map with an observed genome length of 2300 cM covering 87% of the total P. alba genome. The larger number of test-cross markers detected for the P. alba parent than for the P. adenopoda parent might be due to a higher level of heterozygosity in the former than in the latter. In this study, we detected only a small percentage (2%) of the intercross dominant markers heterozygous in both parents and segregating 3:1 in the progeny. The further focus in this mapping study should be on the identification of more intercross markers, to align the two parent-specific maps into a consensus map for mapping important genes causing species differentiation during long evolutionary divergences.

[Study of blood dynamics of ophthalmic artery in patients with sudden sensorineural hearing loss using color Doppler flow imaging]

OBJECTIVE

To investigate the relationship between the pathogenesis of sudden sensorineural hearing loss (SSHL) and the disorder of blood circulation in inner ear.

METHOD

Blood dynamics of the ophthalmic artery were studied quantitatively using color doppler imaging in 34 patients with SSHL.

RESULT

Compared with 34 self-controls and 15 normal controls, 28 patients (82.4%) with SSHL had significantly lower blood flow velocities and higher resistance indices (P < 0.05), and there was no significant difference between the self-control group and the normal control group (P > 0.05).

CONCLUSION

The study suggested that the blood situations--the decreased blood flow velocities and perfusion and increased resistance of ophthalmic artery in patients with SSHL maybe play a role in the pathogenesis of SSHL.