Cyanobacteria as a critical reservoir of the environmental antimicrobial resistome

Antimicrobial resistance (AMR) is predicted to cause a worldwide annual toll of 10 million deaths by 2050. This looming public health threat has been linked to antibiotic overuse and pollution, which places selective pressures on AMR maintenance and transfer in and between microbial populations. We examined the distribution, diversity and potential mobility of AMR genes in cyanobacteria. While cyanobacteria are not pathogenic, we hypothesised that they could be a major environmental reservoir for AMR genes. Genes encoding AMR to seven antimicrobial drug classes were found in 10% of cyanobacterial genomes. AMR genes were found in 13% of freshwater, 19% of terrestrial, 34% of symbiotic, 2% of thermal spring, and 3% of marine genomes. AMR genes were found in five cyanobacterial orders with 23% of Nostocales and 8% of Oscillatoriales strains containing AMR genes. The most frequently observed alleles were ansamycin resistance genes, which were present in 7% of strains. AMR genes responsible for resistance to broad-spectrum β-lactams, chloramphenicols, tetracyclines, macrolides, and aminoglycosides were associated with mobile genetic elements or plasmid replicons or both. These results suggest that cyanobacteria are an extensive reservoir, and potential vector, for AMR genes in diverse terrestrial and aquatic habitats.

Do all ischemic stroke subtypes benefit from organized inpatient stroke care?

BACKGROUND

There are limited data on the effectiveness of organized stroke care in different ischemic stroke subtypes in the real-world setting. We analyzed the effect of organized stroke care in all stroke subtypes in a longitudinal cohort study using data from the Registry of the Canadian Stroke Network.

METHODS

Between July 2003 and September 2007, there were 6,223 consecutive patients with ischemic stroke subtype information by Trial of Org 10172 in Acute Stroke Treatment criteria. Subtypes were categorized as large artery atherosclerotic disease, lacunar, cardioembolic, or other. The amount of organized stroke care was quantified using the previously published organized care index (OCI), graded 0-3 based on the presence or absence of occupational therapy or physiotherapy, stroke team assessment, and admission to a stroke unit.

RESULTS

Mortality at 30 days was associated with both stroke subtype and OCI. Higher OCI (defined as score 2-3 compared to 0-1) was strongly associated with lower odds of 30-day mortality in each ischemic stroke subtype (adjusted odds ratio estimates ranged from 0.16 to 0.43, p < 0.001, controlling for age, gender, stroke severity, and medical comorbidities by logistic regression). These estimates were essentially unchanged after excluding patients treated with palliative care. Numbers needed to treat, to prevent 1 death at 30 days, ranged from 4 to 9 across the subtypes.

CONCLUSIONS

A strong association between higher OCI and lower 30-day mortality was apparent in each ischemic stroke subtype. These data suggest that organized stroke care should be provided to stroke patients regardless of stroke subtype.

Aspects of infection in intensive care unit--prevention and control

Nosocomial infections are the main source of infection in a hospitalized patient. Source of contaminant may be multiple. In a cardiac ICU the vulnerable open heart surgery patients are with multiple invasive lines and monitors. Pediatrics and neonates are more vulnerable because of their poor immunity and nutritional debility. Frequent indwelling line access makes a patient more prone to systemic infection with variable organisms. Our aim is to minimize the chances of hospital acquired infection as far as possible by the use of systemic approach to the patients as guided by the international standard hospital protocol.

Loss of PTEN expression as a prognostic marker for tongue cancer

BACKGROUND

Abnormalities of PTEN, a candidate tumor suppressor gene located at 10q23.3, play an important role in the tumorigenesis of multiple tumor types.

OBJECTIVES

To investigate the expression of PTEN and its clinical implication in squamous cell carcinoma of the tongue.

DESIGN

Retrospective analysis of PTEN protein expression in archived primary oral tongue tumor samples.

SETTING

Academic center.

PATIENTS AND METHODS

PTEN expression was determined by immunohistochemical analysis in tissue samples from 41 patients with stage II, III, and IV squamous cell carcinoma of the tongue. All the patients underwent curative surgical treatment with a median follow-up of 81 months. The Kaplan-Meier method was used for survival analysis. Multivariate analysis was performed according to the Cox proportional hazards model.

RESULTS

Lack of staining for PTEN was demonstrated in 12 (29%) of the 41 tumors. Patients whose tumors lacked PTEN expression had a significantly shorter overall survival time (P = .03) and event-free survival time (P = .01) than those patients with positive PTEN expression. Multivariate regression analysis demonstrated that PTEN expression is an independent predictor of poor outcome when compared with tumor stage and nodal status.

CONCLUSIONS

Although genetic alterations of the PTEN gene are rare in head and neck squamous cell carcinoma, loss of PTEN is not an uncommon event in squamous cell carcinoma of the tongue. Lack of PTEN expression may be an independent prognostic indicator for clinical outcome in patients with this tumor type.

Activation of melanoma antigen tumor antigens occurs early in lung carcinogenesis

The melanoma antigen (MAGE)-encoding genes are expressed in various tumor types, including lung, and are thought to be silent in all normal tissues except testis. In search of biomarkers for early lung cancer detection and cancer risk assessment, we investigated frequencies of expressional activation of MAGE-A1, -A3, and -B2 genes in non-small cell lung cancers (NSCLCs). Expression of these genes was evaluated by reverse transcription-PCR (RT-PCR) in 20 primary NSCLC samples and corresponding normal lung tissues as well as in 20 bronchial brush specimens from former smokers without lung cancer. mRNA in situ hybridization was done to confirm the gene expression pattern at the cellular level. Methylation-specific PCR was performed to evaluate the hypomethylation status of CpG sites in the promoter regions of these genes. Among the 20 primary NSCLC samples analyzed, 14 (70%) expressed MAGE-A1 and 17 (85%) each expressed MAGE-A3 and MAGE-B2. A substantial number of normal lung tissues adjacent to NSCLC also had a detectable level of MAGE expression (65, 75, and 80% for MAGE-A1, -A3, and -B2, respectively). We found that 7 (35%), 10 (50%), and 11 (55%) of the adjacent normal lung tissue samples exhibited promoter hypomethylation at MAGE-A1, -A3, and -B2, respectively, compared with 15 (75%), 16 (80%), and 16 (80%) of the NSCLC samples. Among the 20 bronchial epithelium samples from former smokers, 7 (35%), 10 (50%), and 12 (60%) had also detectable -A1, -A3, and -B2 expression, respectively. Activation of MAGE-A1, -A3, and -B2 genes is common not only in NSCLC but also in bronchial epithelium with severe carcinogen insult. These results suggest that MAGE genes may be activated very early in lung carcinogenesis and may be considered as targets for lung cancer prevention.

Clinical significance of cyclin B1 protein expression in squamous cell carcinoma of the tongue

PURPOSE

Cyclin B1 plays an important role in control of the G(2)-M transition of the cell cycle. We have shown recently that overexpression of cyclin B1 is associated with poor outcome in patients with early stage squamous cell carcinoma (SCC) of the lung.

EXPERIMENTAL DESIGN

To determine the role of cyclin B1 in SCC of the tongue, we analyzed tumor specimens from 41 patients with stage II-IV SCC of the tongue who underwent curative surgery using immunohistochemistry.

RESULTS

The median follow-up of all patients was 83 months. Overexpression of cyclin B1 was observed in 15 (37%) of the 41 tumors, a similar frequency to that found in SCC of the lung. Patients whose tumors showed overexpression of cyclin B1 had a poor event-free survival compared with those lacking this feature (P = 0.04 by Log-rank test). Multivariate analysis of traditional clinical/pathological factors showed that cyclin B1 overexpression was an independent prognostic indicator.

CONCLUSIONS

Our study indicates that cyclin B1 is overexpressed in a subset of SCC of the tongue and is associated with a more aggressive biological behavior of the disease.

Angiotensin II binding and extracellular matrix remodelling in a rat model of myocardial infarction

Clinical evidence points to a role for angiotensin II (Ang II) in the post-infarction remodelling of cardiac hypertrophy. The present study was designed to investigate the remodelling process in an animal model of myocardial infarction (MI) using the following criteria: 1) histological studies to examine the re-vascularisation process and collagen deposition in different regions of the myocardium; 2) histological evidence to investigate the cell type distribution using cell-specific markers; 3) histological and Western blot analysis to localise Ang II receptor subtypes (AT(1)-receptor and AT(2)-receptor) and to study their regulation; 4) kinetics of the binding of Ang II to its receptors in a heart perfusion model; and 5) to assess the effect of the Ang II antagonist (losartan) on these parameters. MI was induced by ligation of the left anterior descending coronary artery of Sprague-Dawley rats. Four different animal groups were established: 1) sham-operated, non-treated; 2) sham-operated, treated with losartan; 3) myocardial infarct, non-treated; and 4) myocardial infarct, treated with losartan. In infarcted rat hearts, fibroblasts and collagen types I and III increased in the remnant viable region of the left ventricle compared with sham-operated rats. One month of losartan treatment in myocardial infarcted rats revealed insignificant changes in fibroblasts and collagen types I and III compared with sham controls. Also, myocardial infarction increased AT(1)-receptor protein levels compared with sham-operated controls, as judged by Western blotting. In losartan-treated myocardial infarct animals, no changes were detected at the level of AT(1)-receptor expression compared with non-treated myocardial infarct rats. Binding studies of Ang II on endothelial cell lining and directly on myocytes in sham-operated and infarcted perfused rat hearts revealed that, in myocardial infarcted-animals, Ang II binding affinity increased both in the endothelium and in myofibres. This may be considered a major putative effect of the peptide in potentiating the pharmacodynamics of hypertrophy. In losartan-treated myocardial infarcted-animals, a marked increase in the binding affinities of Ang II for the AT(2)-receptor subtype was observed. Hence, potential cardioprotective effects of the AT(1)-receptor antagonist are proposed.