Clearance of Pseudomonas aeruginosa Foreign-Body Biofilm Infections through Reduction of the Cyclic Di-GMP Level in the Bacteria

Opportunistic pathogenic bacteria can engage in biofilm-based infections that evade immune responses and develop into chronic conditions. Because conventional antimicrobials cannot efficiently eradicate biofilms, there is an urgent need to develop alternative measures to combat biofilm infections. It has recently been established that the secondary messenger cyclic diguanosine monophosphate (c-di-GMP) functions as a positive regulator of biofilm formation in several different bacteria. In the present study we investigated whether manipulation of the c-di-GMP level in bacteria potentially can be used for biofilm control in vivo. We constructed a Pseudomonas aeruginosa strain in which a reduction in the c-di-GMP level can be achieved via induction of the Escherichia coli YhjH c-di-GMP phosphodiesterase. Initial experiments showed that induction of yhjH expression led to dispersal of the majority of the bacteria in in vitro-grown P. aeruginosa biofilms. Subsequently, we demonstrated that P. aeruginosa biofilms growing on silicone implants, located in the peritoneal cavity of mice, dispersed after induction of the YhjH protein. Bacteria accumulated temporarily in the spleen after induction of biofilm dispersal, but the mice tolerated the dispersed bacteria well. The present work provides proof of the concept that modulation of the c-di-GMP level in bacteria is a viable strategy for biofilm control.     

Different regulation of p27 and Akt during cardiomyocyte proliferation and hypertrophy

Postnatal cardiomyocytes normally grow by hypertrophy but show a limited proliferate response to certain stimuli. Although the proliferative capacity declines shortly after birth, neonatal cardiomyocytes can grow both by hypertrophy and by proliferation. Therefore, we have used neonatal cardiomyocytes to investigate the molecular differences between hypertrophic and proliferative growth of cardiomyocytes. Stimulation of neonatal cardiomyocytes with angiotensin II mainly induced hypertrophy, whereas PDGF only had a minor effect on the size of the myocytes. In contrast, PDGF induced significant proliferation in the cardiomyocyte cultures whereas angiotensin II treatment only resulted in a small increase in the number of cells. Measurement of cyclin D-dependent kinase specific phosphorylation of pRb by immunohistochemistry showed that, both stimuli activate the G1 phase of the cell cycle. By western blotting we found that PDGF-induced proliferation correlates with activation of Akt, inactivation of GSK-3β and downregulation of the cyclin-dependent kinase inhibitor p27, whereas angiotensin II only had a small effect on Akt, GSK-3β and p27. Our data support the hypothesis that, the hypertrophic and proliferative responses are both activated by G1 cell cycle molecules. The difference between the two responses appears to be that high amounts of p27 are present during hypertrophic growth, whereas proliferation involves downregulation of p27 and GSK-3β activity and upregulation of Akt.     

New population-based exome data are questioning the pathogenicity of previously cardiomyopathy-associated genetic variants

Cardiomyopathies are a heterogeneous group of diseases with various etiologies. We focused on three genetically determined cardiomyopathies: hypertrophic (HCM), dilated (DCM), and arrhythmogenic right ventricular cardiomyopathy (ARVC). Eighty-four genes have so far been associated with these cardiomyopathies, but the disease-causing effect of reported variants is often dubious. In order to identify possible false-positive variants, we investigated the prevalence of previously reported cardiomyopathy-associated variants in recently published exome data. We searched for reported missense and nonsense variants in the NHLBI-Go Exome Sequencing Project (ESP) containing exome data from 6500 individuals. In ESP, we identified 94 variants out of 687 (14%) variants previously associated with HCM, 58 out of 337 (17%) variants associated with DCM, and 38 variants out of 209 (18%) associated with ARVC. These findings correspond to a genotype prevalence of 1:4 for HCM, 1:6 for DCM, and 1:5 for ARVC. PolyPhen-2 predictions were conducted on all previously published cardiomyopathy-associated missense variants. We found significant overrepresentation of variants predicted as being benign among those present in ESP compared with the ones not present. In order to validate our findings, seven variants associated with cardiomyopathy were genotyped in a control population and this revealed frequencies comparable with the ones found in ESP. In conclusion, we identified genotype prevalences up to more than one thousand times higher than expected from the phenotype prevalences in the general population (HCM 1:500, DCM 1:2500, and ARVC 1:5000) and our data suggest that a high number of these variants are not monogenic causes of cardiomyopathy.     

Are the High Hip Fracture Rates Among Norwegian Women Explained by Impaired Bone Material Properties?

Hip fracture rates in Norway rank among the highest in the world, more than double that of Spanish women. Previous studies were unable to demonstrate significant differences between the two populations with respect to bone mass or calcium metabolism. In order to test whether the difference in fracture propensity between both populations could be explained by differences in bone material quality we assessed bone material strength using microindentation in 42 Norwegian and 46 Spanish women with normal BMD values, without clinical or morphometric vertebral fractures, no clinical or laboratory signs of secondary osteoporosis, and without use of drugs with known influence on bone metabolism. Bone material properties were assessed by microindentation of the thick cortex of the mid tibia following local anesthesia of the area using the Osteoprobe device (Active Life Scientific, Santa Barbara, CA, USA). Indentation distance was standardized against a calibration phantom of methylmethacrylate and results, as percentage of this reference value, expressed as bone material strength index units (BMSi). We found that the bone material properties reflected in the BMSi value of Norwegian women was significantly inferior when compared to Spanish women (77 ± 7.1 versus 80.7 ± 7.8, p < 0.001). Total hip BMD was significantly higher in Norwegian women (1.218 g/cm² versus 0.938 g/cm², p < 0.001) but regression analysis revealed that indentation values did not vary with BMD r² = 0.03 or age r² = 0.04. In conclusion Norwegian women show impaired bone material properties, higher bone mass, and were taller than Spanish women. The increased height will increase the impact on bone after falls, and impaired bone material properties may further enhance the risk fracture after such falls. These ethnic differences in bone material properties may partly explain the higher propensity for fracture in Norwegian women. © 2015 American Society for Bone and Mineral Research.     

AN ELASTIC EXERCISE BAND MOUNTED WITH A BANDCIZER? CAN DIFFERENTIATE BETWEEN COMMONLY PRESCRIBED HOME EXERCISES FOR THE SHOULDER

Background

Home‐exercise is commonly prescribed for rehabilitation of the shoulder following injury. There is a lack of technology available to monitor if the patient performs the exercises as prescribed.

Purpose

The purpose of this study was to investigate the validity of using three dimensional (3D) gyroscope data recorded with the Bandcizer™ sensor to differentiate between three elastic band exercises performed in the shoulder joint: abduction, flexion, and external rotation.

Design

Concurrent validity study.

Methods

This study was performed over two phases. In the first phase, 20 subjects performed three sets of 10 of shoulder abduction, external rotation and flexion exercises with a Thera‐Band mounted with a Bandcizer, while supervised by a physical therapist. The Bandcizer has an inbuilt three‐dimensional gyroscope, capable of measuring angular rotation. Gyroscope data were analyzed in Matlab, and a one‐way ANOVA was used to test for significant differences between each of the three exercises. An algorithm was then created in Matlab based on the exercise‐data from the gyroscope, to enable differentiation between the three shoulder exercises. Twenty new subjects were then recruited to cross‐validate the algorithm and investigate if the algorithm could differentiate between the three different shoulder exercises.

Results

A blinded assessor using the Matlab algorithm could correctly identify 56 out of 60 exercise sets. The kappa agreement for the three exercises ranged between 0.86‐0.91.

Conclusion

The ability to differentiate between the home exercises performed by patients after shoulder injury has great implications for future clinical practice and research. When home exercises are the treatments‐of‐choice, clinicians will be able to quantify if the patient performed the exercise as intended. Further research should be aimed at investigating the feasibility of using the Bandcizer™ in a home‐based environment.

Word count

2429

Level of Evidence

2     

Schizophrenia and Metacognition: An Investigation of Course of Illness and Metacognitive Beliefs Within a First Episode Psychosis

Cognitive Therapy and Research - The Self Regulatory Executive Function (S-REF) model implicates maladaptive metacognitive beliefs and processes in the predisposition and/or maintenance of positive...