Recovery of soil streptomycetes from arid habitats in Jordan and their potential to inhibit multi-drug resistant <Emphasis Type="Italic">Pseudomonas aeruginosa</Emphasis> pathogens

A total of 161 different Streptomyces isolates were recovered from 5 soil samples representing the driest habitats of Jordan. These were then characterized and assessed for their antagonistic activity against four clinical multi-drug resistant Pseudomonas aeruginosa test pathogens. Results indicated that only 3 strains out of 139 and 6 out of 22 isolated at 27°C and 45°C, respectively, were active against at least three strains of pathogenic Pseudomonas. However, three Streptomyces strains (J_2b, J₄, and J₁₂) that were isolated at 45°C inhibited all of the tested pathogens with an inhibition zone ranging between 5 and 16 mm in diameter. Data obtained from comparing the inhibition activity of these unique Streptomyces strains toward multi-resistant Pseudomonas pathogens with standard used antibiotics revealed that these isolates produce possible different inhibitory bioactive compounds other than the standard antibiotics.     

PSGL-1 from the murine leukocytic cell line WEHI-3 is enriched for core 2-based O-glycans with sialyl Lewis x antigen

Leukocyte trafficking involves specific recognition between P-selectin and L-selectin and PSGL-1 containing core 2-based O-glycans expressing sialyl Lewis x (SLe(x)) antigen. However, the structural identity of the glycan component(s) displayed by murine neutrophil PSGL-1 that contributes to its P-selectin counter-receptor activity has been uncertain, since these cells express little if any SLe(x) antigen, and because there have been no direct studies to examine murine PSGL-1 glycosylation. To address this uncertainty, we studied PSGL-1 glycosylation in the murine cell line WEHI-3 using metabolic-radiolabeling with (3)H-monosaccharide precursors to detect low-abundance O-glycan structures. We report that PSGL-1 from WEHI-3 cells expresses a di-sialylated core 2 O-glycan containing the SLe(x) antigen. This fucosylated O-glycan is scarce on PSGL-1 and essentially undetectable in total leukocyte glycoproteins from WEHI-3 cells. These results demonstrate that WEHI-3 cells selectively fucosylate PSGL-1 to generate functionally important core 2-based O-glycans containing the SLe(x) antigen.     

Ecosystem Approach to Human Health in Two Villages of the North Jordan Valley: Scoping the Problems

North Jordan Valley (NJV) is a narrow rift valley that extends from lake Tiberius in the north to the Dead Sea in the south. It follows the River Jordan and contains the most fertile lands in Jordan. With a population around 140,000, primarily working in agriculture, NJV is Jordan’s premier agricultural production area. NJV is an ecosystem that is stressed both naturally and by human activities. Limited precipitation and very hot summer seasons are stresses that are inherent parts of the ecosystem itself. However, human activities like agriculture, poor sanitation, and tourism produce health risks to the people through the pollution and degradation of natural resources. The area also faces several socioeconomic problems such as poverty, large family size, and unemployment. In NJV, women typically work at home as housewives taking care of large families and are engaged in agricultural activities through which they are exposed, along with men and children, to high temperature and high concentration of pesticides. This article presents the findings of a Participatory Rapid Appraisal (PRA) study that focused on assessing local communities’ perception and awareness of the linkages between disruption of the ecosystem and prevailing public health problems. From an academic point of view, one of the key challenges of implementing ecosystem approaches to human health is the incorporation of various stakeholders as full partners throughout the research process rather than as contributors to a research designed from the sole perspective and interests of the academic research team. This study was conceptualized as a preliminary study to guide and inform the design of a larger research study on health and environment linkages in the NJV. The process was considered key for ensuring that research questions would reflect and build upon the priorities of multiple stakeholders, including community members, and would involve them in the design of the research. In addition to the successful involvement of local communities and other stakeholders in the identification of primary health problems and community priorities in the study area, the research played a key role in introducing various stakeholders to the basics of the Ecosystem Approaches to Human Health (Ecohealth) concept. The study took place in two small villages in NJV (Tal Al-Arbaeen and Tal Al-Menteh). The first village is located upstream of the junction point where King Abdullah Canal’s fresh water mixes with marginal quality water of King Talal Reservoir (KTR) while the second one is situated downstream. Results of this study showed that local communities are generally aware of the linkages between the health of the ecosystem and human health and well-being. According to the results of the study, key stressors to the environment (socioeconomic and institutional) include the use/abuse of agrochemicals and household insecticides, spread of flies (associated to organic agriculture), mismanagement of organic fertilizers, lack of sanitation services, unsanitary household conditions, and a serious problem of stray dogs and rodents. Problems associated with poverty and large family size were also commonly mentioned. Diarrhea, respiratory diseases, and infectious and parasitic diseases were believed to be the most common health problems in both villages. Local communities showed great interest and concern for the various health problems to which they are confronted and expressed eagerness to contribute to potential mitigation/intervention measures.     

Validation of an in vivo method for monitoring ovarian development in the grey mullet (Mugil cephalus L.)

The validity of using extruded intra-ovarian oocytes for in vivo assessment of ovarian maturity in the grey mullet was established. The diameter of sampled, unfixed oocytes was used as a reference point for comparative purposes. Analysis of variations in oocyte diameters among samples removed from seven different ovarian locations indicated that mullet oocytes develop in synchrony and that in vivo samples taken from any area in the ovary would be representative of the entire ovary. Statistical analyses of oocyte diameters and diameter-frequency distributions data from duplicate in vivo samples removed from the same ovarian site in each of 17 females showed no significant differences and validated the accuracy of the method. Similar comparisons of data from in vivo and in vitro samples revealed no statistically significant differences.     

In Vivo Dynamic Deformation of Articular Cartilage in Intact Joints Loaded by Controlled Muscular Contractions

When synovial joints are loaded, the articular cartilage and the cells residing in it deform. Cartilage deformation has been related to structural tissue damage, and cell deformation has been associated with cell signalling and corresponding anabolic and catabolic responses. Despite the acknowledged importance of cartilage and cell deformation, there are no dynamic data on these measures from joints of live animals using muscular load application. Research in this area has typically been done using confined and unconfined loading configurations and indentation testing. These loading conditions can be well controlled and allow for accurate measurements of cartilage and cell deformations, but they have little to do with the contact mechanics occurring in a joint where non-congruent cartilage surfaces with different material and functional properties are pressed against each other by muscular forces. The aim of this study was to measure in vivo, real time articular cartilage deformations for precisely controlled static and dynamic muscular loading conditions in the knees of mice. Fifty and 80% of the maximal knee extensor muscular force (equivalent to approximately 0.4N and 0.6N) produced average peak articular cartilage strains of 10.5±1.0% and 18.3±1.3% (Mean ± SD), respectively, during 8s contractions. A sequence of 15 repeat, isometric muscular contractions (0.5s on, 3.5s off) of 50% and 80% of maximal muscular force produced cartilage strains of 3.0±1.1% and 9.6±1.5% (Mean ± SD) on the femoral condyles of the mouse knee. Cartilage thickness recovery following mechanical compression was highly viscoelastic and took almost 50s following force removal in the static tests.     

Fluorescence recovery after photobleaching: direct measurement of diffusion anisotropy

Biomechanics and Modeling in Mechanobiology - Fluorescence recovery after photobleaching (FRAP) is a widely used technique for studying diffusion in biological tissues. Most of the existing...     

Review: Diagnosis and treatment of dementia: 3. Mild cognitive impairment and cognitive impairment without dementia

Background

Mild cognitive impairment and cognitive impairment, no dementia, are emerging terms that encompass the clinical state between normal cognition and dementia in elderly people. Controversy surrounds their characterization, definition and application in clinical practice. In this article, we provide physicians with practical guidance on the definition, diagnosis and treatment of mild cognitive impairment and cognitive impairment, no dementia, based on recommendations from the Third Canadian Consensus Conference on the Diagnosis and Treatment of Dementia, held in March 2006.

Methods

We developed evidence-based guidelines using systematic literature searches, with specific criteria for study selection and quality assessment, and a clear and transparent decision-making process. We selected studies published from January 1996 to December 2005 that had mild cognitive impairment or cognitive impairment, no dementia, as the outcome. Subsequent to the conference, we searched for additional articles published between January 2006 and January 2008. We graded the strength of evidence using the criteria of the Canadian Task Force on Preventive Health Care.

Results

We identified 2483 articles, of which 314 were considered to be relevant and of good or fair quality. From a synthesis of the evidence in these studies, we made 16 recommendations. In brief, family physicians should be aware that most types of dementia are preceded by a recognizable phase of mild cognitive decline. They should be familiar with the concepts of mild cognitive impairment and of cognitive impairment, no dementia. Patients with these conditions should be closely monitored because of their increased risk for dementia. Leisure activities, cognitive stimulation and physical activity could be promoted as part of a healthy lifestyle in elderly people and those with mild cognitive impairment. Vascular risk factors should be treated optimally. No other specific therapies can yet be recommended.

Interpretation

Physicians will increasingly see elderly patients with mild memory loss, and learning an approach to diagnosing states such as mild cognitive impairment is now warranted. Close monitoring for progression to dementia, promotion of a healthy lifestyle and treatment of vascular risk factors are recommended for the management of patients with mild cognitive impairment.

Articles to date in this series

• Chertkow H. Diagnosis and treatment of dementia: Introduction. Introducing a series based on the Third Canadian Consensus Conference on the Diagnosis and Treatment of Dementia. CMAJ 2008;178:316-21.
• Patterson C, Feightner JW, Garcia A, et al. Diagnosis and treatment of dementia: 1. Risk assessment and primary prevention of Alzheimer disease. CMAJ 2008;178:548-56.
• Feldman HH, Jacova C, Robillard A, et al. Diagnosis and treatment of dementia: 2. Diagnosis. CMAJ 2008;178:825-36.

     

Distinct functions of MLH3 at recombination hot spots in the mouse

The four mammalian MutL homologs (MLH1, MLH3, PMS1, and PMS2) participate in a variety of events, including postreplicative DNA repair, prevention of homeologous recombination, and crossover formation during meiosis. In this latter role, MLH1-MLH3 heterodimers predominate and are essential for prophase I progression. Previous studies demonstrated that mice lacking Mlh1 exhibit a 90% reduction in crossing over at the Psmb9 hot spot while noncrossovers, which do not result in exchange of flanking markers but arise from the same double-strand break event, are unaffected. Using a PCR-based strategy that allows for detailed analysis of crossovers and noncrossovers, we show here that Mlh3(-/-) exhibit a 85-94% reduction in the number of crossovers at the Psmb9 hot spot. Most of the remaining crossovers in Mlh3(-/-) meiocytes represent simple exchanges similar to those seen in wild-type mice, with a small fraction (6%) representing complex events that can extend far from the initiation zone. Interestingly, we detect an increase of noncrossovers in Mlh3(-/-) spermatocytes. These results suggest that MLH3 functions predominantly with MLH1 to promote crossovers, while noncrossover events do not require these activities. Furthermore, these results indicate that approximately 10% of crossovers in the mouse are independent of MLH3, suggesting the existence of alternative crossover pathways in mammals.