Distribution of 16S rRNA methylases among different species of Gram-negative bacilli with high-level resistance to aminoglycosides

16S rRNA methylases confer high-level resistance to most aminoglycosides in Gram-negative bacteria. Seven 16S rRNA methylase genes, armA, rmtA, rmtB, rmtC, rmtD, rmtE and npmA, have been identified since 2003. We studied the distribution of methylase genes in more than 200 aminoglycoside-resistant Gram-negative clinical isolates collected in 2007 at our hospital in Shanghai, China. 16S rRNA methylase genes were amplified by polymerase chain reaction (PCR) among 217 consecutive clinical isolates of Gram-negative bacilli resistant to gentamicin and amikacin by a disk diffusion method. 16S rRNA methylase genes were present in 97.5% (193/198) of clinical isolates highly resistant to amikacin (≥512 μg/ml), with armA and rmtB detected in 67.2 and 30.3% of strains, respectively, while no 16S rRNA methylase genes were detected in 19 strains with amikacin minimum inhibitory concentration (MIC) ≤256 μg/ml. armA or rmtB genes were detected in 100% of 104 strains of Enterobacteriaceae, and these two genes were equally represented (49 vs. 55 strains). Genes for armA or rmtB were detected in 94.7% (89/94) of Acinetobacter baumannii and Pseudomonas aeruginosa strains, and armA was predominant (84 vs. 5 strains with rmtB). No rmtA, rmtC, rmtD or npmA genes were found. Enterobacterial repetitive intergenic consensus sequence (ERIC-PCR) indicated that armA and rmtB genes were spread by both horizontal transfer and clonal dissemination.

CD spectrum of bacteriorhodopsin: Best evidence against exciton model

We summarize the predictions of the exciton model that was originally proposed to explain the observed biphasic band shape of its CD spectrum in the visible region of bacteriorhodopsin (bR). It is shown that to reconcile these predictions with the observed results on the linear dichroism, the retinal isomerization time and, the retinal-retinal distance, the biphasic nature of the observed CD spectrum of bR becomes itself an evidence against the exciton model because of the uncertainty principle.Reduced bR (RbR), which retains its hexagonal structure, shows a monophasic CD spectrum with relatively small rotational strength as compared to bR. This is shown to disagree with predictions made by the exciton model. The results could best be explained in terms of retinal-protein heterogeneity leading to two or more types of bR in which their retinals suffer opposite sense of intramolecular rotational distortion along their retinal long axis. Such a retinal-protein heterogeneity disappears in reduced bR which is known to have a planar (nondistorted) retinal conjugated system, resulting in a monophasic CD with reduced rotational strength, as observed.

Circular dichroism and photocycle kinetics of partially detergent solubilized and partially retinal regenerated bacteriorhodopsin

The circular dichroism (CD) spectra and the kinetics of the M(412) formation have been determined and compared for bacteriorhodopsin (bR) partially delipidated by the addition of Triton X-100 and partially reconstituted by the addition of retinal to apoprotein at pH 6.8 and 22 degrees C. As the degree of delipidation increases or the fraction of reconstitution decreases, the following observations are made: (a) the shape of the visible CD band changes from biphasic, as found in bR, to a single monomer type band; (b) the CD spectra and the deprotonation rate constants change in a similar way; (c) the relative amplitudes of the components of the deprotonation kinetics do not change upon reconstitution, but change greatly upon delipidation. These results lead to the conclusion that the CD band shape as well as the deprotonation rate constants are sensitive to one type of perturbation, which is linked to the retinal structure within the protein environment, whereas the relative amplitudes of the components of the deprotonation kinetics are sensitive to another type, which may be linked to acid-base equilibria of the amino acid side groups within the active site.

Genomic polymorphisms within alpha 7 nicotinic acetylcholine receptor and severe sepsis in Chinese Han population

Alpha 7 nicotinic acetylcholine receptor, a kind of ligand-gated ion channel mainly expressed in macrophages, plays a crucial role in improving survival in sepsis via suppressing proinflammatory cytokines. The predisposition of genomic polymorphisms within alpha 7 nicotinic acetylcholine receptor gene (CHRNA7) to sepsis has not been investigated. The current association study was performed to analyse six common genetic variations within 5'-upstream region of CHRNA7 gene in 229 patients with severe sepsis and 267 controls. Neither allelic frequencies nor genotype distributions were significantly different between patients and controls, as well as between surviving and nonsurviving patients. The frequencies of estimated haplotypes were also comparable between above defined groups. The present study suggests that genomic polymorphisms in the 5'-upstream region of CHRNA7 gene may not be a major risk factor for severe sepsis in Chinese Han population.

Increased risk of high-grade hypertension with bevacizumab in cancer patients: a meta-analysis

BACKGROUND

Hypertension is associated with the use of bevacizumab, an angiogenesis inhibitor widely used in cancer therapy. Currently, the risk of severe hypertension associated with bevacizumab is unclear. We performed a systematic review and meta-analysis of published randomized-controlled clinical trials (RCTs) to assess the risk of high-grade hypertension in cancer patients treated with bevacizumab.

METHODS

Databases from PUBMED, the Web of Science, and abstracts presented at the American Society of Clinical Oncology conferences until May 2009 were searched to identify relevant studies. Eligible studies included prospective RCTs in which bevacizumab was directly compared with controls in cancer patients receiving concurrent antineoplastic therapy. Summary incidence, relative risk (RR), and 95% confidence interval (CI) were calculated employing a fixed- or random-effects model based upon the heterogeneity of the included studies.

RESULTS

A total of 12,656 patients with a variety of tumors from 20 studies were included for the analysis. The incidence of all-grade hypertension in patients receiving bevacizumab was 23.6% (95% CI: 20.5-27.1) with 7.9% (95% CI: 6.1-10.2) being high-grade (grade 3 or 4). Patients treated with bevacizumab had a significantly increased risk of developing high-grade hypertension with an RR of 5.28 (95% CI: 4.15-6.71, P < 0.001) in comparison with controls. Even though not statistically significant, there was a trend suggesting that bevacizumab may increase the risk of hypertensive crisis (grade 4) with an RR of 3.16 (95% CI: 0.91-10.90). The increased risk of high-grade hypertension was observed in patients receiving bevacizumab at 2.5 mg/kg/week (RR = 4.78, 95% CI: 3.59-6.36) as well as 5 mg/kg/week (RR = 5.39, 95% CI: 3.68-7.90). The risk of high-grade hypertension may vary with tumor types, with RRs ranging from 2.49 (95% CI: 0.94-6.59) in patients with mesothelioma to 14.80 (95% CI: 0.92-238.51) in patients with breast cancer.

CONCLUSION

Bevacizumab may significantly increase the risk of high-grade hypertension in cancer patients. Close monitoring and adequate management are highly recommended to decrease cardiovascular complications.

Surgical treatment of a 56-year-old woman with an intracardiac type of total anomalous pulmonary venous connection

Total anomalous pulmonary venous connection (TAPVC) is a rare congenital cardiac anomaly. Death usually occurs in the first 3 months of life in about 50% of neonates with this disease, and no more than 20% of patients survive to the age of 1 year. The patient with the longest recorded survival is 49 years old. Here, we report successful surgical treatment of this disease in a 56-year-old female patient. This patient was discharged in good health about 1 month after operation, with no evidence of recurrence of heart failure at 13 months' follow-up.

Menopausal transition and changes of body composition: a prospective study in Chinese perimenopausal women

OBJECTIVES

Whether age or menopause per se influences fat distribution remains controversial. This study aimed to investigate the change of body composition, particularly body fat distribution, in relation to menopausal transition in a 30-month prospective study of perimenopausal women.

METHODS

A total of 438 community-based healthy women aged 44-55 years participated in the Hong Kong Perimenopausal Women Osteoporosis Study. Data were obtained at baseline, and at 9-, 18- and 30-month during the follow-up. Soft tissue measurements consisting of fat mass and lean muscle mass of the trunk and whole body were obtained by the dual energy X-ray absorptiometry. Percentage change of body measurements over the follow-up period was compared between women who remained premenopausal, those who went through menopausal transition, and those who were menopausal since baseline.

RESULTS

A slight decrease in the lean mass but an increase in the total fat mass and trunk fat mass (TFM) over the follow-up period were noted. Multivariate linear regression analysis showed that age was negatively associated with an increase in central obesity. Adjusted for the important predictors--age, age of menarche and education level, menopausal status was a significant and independent predictor of the decrease in lean mass and the increase in percent of body fat, TFM and trunk-leg fat mass ratio.

CONCLUSION

Our 30-month longitudinal study showed that menopause has an independent effect on an increase in fat mass, and an increase in central obesity in perimenopausal Chinese women.

Multiple microRNAs modulate p21Cip1/Waf1 expression by directly targeting its 3' untranslated region

Cyclin-dependent kinase inhibitor 1A (CDKN1A), also known as p21Cip1/Waf1, is a master downstream effector of tumor suppressors. In this study, we experimentally demonstrate through a high-throughput luciferase reporter screen that p21Cip1/Waf1 can be directly targeted by nearly 28 microRNAs (miRNAs). The results were further confirmed by a series of mutational analyses and luciferase reporter assays. These 28 miRNAs can substantially inhibit p21Cip1/Waf1 expression, predominantly at translational level. Many of these miRNAs were upregulated in cancers and might serve as modulators of oncogenesis. Furthermore, 8 of these 28 p21-regulating miRNAs are located in the chromosome 19 miRNA cluster, the largest miRNA gene cluster in humans, and they can clearly promote cell proliferation and cell-cycle progression in choriocarcinoma cells. In conclusion, our screening strategy provides an alternative approach to uncovering miRNA modulators of an individual mRNA, and it has identified multiple miRNAs that can suppress p21Cip1/Waf1 expression by directly targeting its 3' untranslated region.

Antihypertensive and anti-arrhythmic effects of an extract of Radix Stephaniae Tetrandrae in the rat

In this study, we determined the effects of an extract of Radix Stephaniae Tetrandrae (RST) on arterial blood pressure and heart weight in deoxycorticosterone acetate-salt (DOCA-salt) hypertensive rats. We also determined the effects of the extract on arrhythmia and infarct induced by myocardial ischaemia and reperfusion in anaesthetized rats. We further compared the effects of the extract with those of tetrandrine, which makes up 7% of the extract and is known to act as a calcium-channel antagonist, and verapamil, a prototype calcium-channel antagonist. Treatment with RST extract returned the arterial blood pressure, cardiac compliance and coronary flow towards normal, and reduced right ventricular hypertrophy in the DOCA-salt hypertensive rat. In the anaesthetized rat, the RST extract reduced arrhythmia and infarct size induced by myocardial ischaemia and reperfusion; the effects were similar to those of tetrandrine and verapamil. The findings indicate that the RST extract acts like a calcium-channel antagonist. It may be used in the treatment of cardiovascular diseases, as are the calcium-channel antagonist and tetrandrine. More interestingly, the effects of the RST extract were of the same potency as tetrandrine. Since only 7% of the extract was tetrandrine, the observation indicates that tetrandrine was not the only component that was responsible for the actions of the extract.

Analysis of genetically engineered oncolytic herpes simplex viruses in human prostate cancer organotypic cultures

Oncolytic herpes simplex viruses type 1 (oHSVs) such as G47Delta and G207 are genetically engineered for selective replication competence in cancer cells. Several factors can influence the overall effectiveness of oHSV tropism, including HSV-1 receptor expression, extracellular matrix milieu and cellular permissiveness. We have taken advantage of human prostate organ cultures derived from radical prostatectomies to investigate oHSV tropism. In this study, we show that both G47Delta and G207 specifically replicate in epithelial cells of the prostatic glands but not in the surrounding stroma. In contrast, both the epithelial and stromal cell compartments were readily infected by wild-type HSV-1. Analysis of oHSV replication in prostate surgical specimens 3 days post infection showed that G47Delta generated approximately 30-fold more viral progeny than did G207. This correlated with the enhanced expression of G47Delta-derived glycoprotein gB protein levels as compared with G207. In benign prostate tissues, G207 and G47Delta titers were notably reduced, whereas strain F titers were maintained at similar levels compared with prostate cancer specimens. Overall, our results show that these oncolytic herpes vectors show both target specificity and replication competence in human prostate cancer specimens and point to the utility of using human prostate organ cultures in assessing oHSV tropism and cellular specificity.

Gender-Dependent Penetrance of Small Heterodimer Partner (SHP) Gene Deficiency in Overweight/Obese Chinese Pedigrees

Mutations of the small heterodimer partner ( SHP) gene have been associated with mild obesity in Japanese subjects. This study was designed to investigate whether there was a similar association in 772 Chinese adults. A total of 272 subjects were normal weight, 423 were overweight and 77 were obese. Four non-synonymous mutations (R34X, H53fsdel10, G171A, G189E) were identified in 10 out of the 500 overweight/obese subjects, but were not seen in the normal weight controls (prevalence 2.00% versus 0.00%, respectively). The relatives of proband carriers, including 25 carriers and 33 non-carriers from three generations, were also screened for 10 multigenerational non-consanguineous pedigrees. A gender-dependent penetrance effect was observed in the pedigrees. Furthermore, the frequency of SHP gene mutations was significantly higher in those with type 2 diabetes compared with the non-diabetics (61.5% versus 28.1%, respectively). These data provide evidence of a gender-dependent effect on penetrance for SHP deficiency and suggest that SHP mutations increase susceptibility to type 2 diabetes.