"Stem cell" origin of the hematopoietic defect in dyskeratosis congenita

We have used the long-term bone marrow culture (LTBMC) system to analyze hematopoiesis in three patients with dyskeratosis congenita (DC), two of whom had aplastic anemia, and the third had a normal blood count (apart from mild macrocytosis) and normal BM cellularity. Hematopoiesis was severely defective in all three patients, as measured by a low incidence of colony-forming cells and a low level of hematopoiesis in LTBMC. The function of the marrow stroma was normal in its ability to support the growth of hematopoietic progenitors from normal marrows seeded onto them in all three cases, but the generation of hematopoietic progenitors from patients marrow cells inoculated onto normal stromas was reduced, thus suggesting the defect to be of stem cell origin. The parents and unaffected brother of one of the families have also been studied in LTBMC and all showed normal hematopoietic and stromal cell function. From this study we speculate that there are some similarities between DC and the defect in the W/Wv mouse.     

Incentives for recruiting trainee participants in medical education research

Introduction: In the growing field of medical education research, participant recruitment can be challenging. Incentives, either tangible or intangible, may be offered to encourage participation. This study aimed to understand these incentives and explore the relationship between study quality and incentives in medical education research.

Methods: We reviewed research studies examining medical trainees published in five major journals in 2008. Tangible and intangible incentives used in recruitment were extracted by two researchers. For each quantitative article, medical education research quality instrument (MERSQI) score was calculated and citation counts for all articles were compiled.

Results: Of 215 included articles, 8% explicitly reported incentives. Tangible incentives (value range $15–$60 USD) were offered in 7.9% of studies. Intangible incentives were identified in 30% of studies but only one specifically discussed their use. Tangible incentives correlated with a higher MERSQI score (p?p?Conclusion: Most studies in medical education did not describe incentives for participation. Information regarding incentives should be reported in all studies to help inform future recruitment efforts and also to understand the study context including factors that may influence participants motivation.     

From recipe to research: introducing undergraduate students to the nature of science using a hybrid practical course centred on drug discovery for neglected diseases

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Improving care for patients with chronic heart failure in the community: the importance of a disease management program

STUDY OBJECTIVE: Utilizing a comparison group of patients with congestive heart failure (CHF) discharged to their primary care physicians, we sought to determine if disease management in a short-term, aggressive-intervention heart failure clinic (HFC) following hospital discharge is associated with improved outcomes. DESIGN: Chart review. SETTING: An integrated health-care center serving a tristate area. PATIENTS: Inclusion criteria were discharge from the hospital with a primary diagnosis of CHF, outpatient follow-up within the hospital system, and the presence of left ventricular systolic dysfunction as the basis for CHF. Patients were categorized into group 1 if they were referred to the HFC after hospital discharge, and into group 2 if follow-up care was provided by their primary care physician. MEASUREMENTS AND RESULTS: There were 38 patients in group 1 and 63 patients in group 2. There was a trend toward a shorter time to the first outpatient visit following discharge (11 days vs 15 days, p = 0.09), more outpatient visits within 90 days (10 visits vs 2 visits, p < 0.001), and more patient-initiated contacts (four contacts vs one contact, p = < 0.001) in group 1 compared to group 2, respectively. The combined hospital readmission and mortality rate at 90 days (10% vs 30%, p < 0.018) and 1 year (21% vs 43%, p < 0.02) was lower in group 1. There was a 77% relative risk reduction for 30-day hospital readmission in favor of group 1, and a statistically lower rate of readmissions at 90 days and 1 year. Utilization and maintenance of standardized CHF medications were significantly higher in patients who attended the HFC. CONCLUSIONS: A comprehensive disease management program for patients discharged with a diagnosis of CHF resulted in fewer rehospitalizations and improved event-free survival compared to patients followed up by their primary care physicians.     

Effectiveness of diclofenac versus paracetamol in knee osteoarthritis: a randomised controlled trial in primary care

Background

The effectiveness of diclofenac versus paracetamol in primary care patients with pain caused by knee osteoarthritis is unclear.

Aim

To assess the effectiveness of diclofenac compared with paracetamol over a period of 2, 4, and 12 weeks in patients with knee osteoarthritis.

Design and setting

Randomised controlled trial in general practice.

Method

There were 104 patients included in the study, they were aged ≥45 years consulting their GP with knee pain caused by knee osteoarthritis. Patients were randomly allocated to diclofenac (n = 52) or paracetamol (n = 52) for at least 2 weeks. Primary outcomes were daily knee pain severity, and knee pain and function measured with the Knee Injury and Osteoarthritis Outcome Score (KOOS).

Results

Over a period of 2- and 4-weeks follow-up, no significant difference in daily knee pain was found between the patient groups: estimated differences of 0.5 (95% CI = −0.2 to 1.3) and −0.2 (95% CI = −1.0 to 0.7), respectively. Over the 12-weeks follow-up, no significant differences were found between both groups for KOOS pain: estimated difference of −2.8 (95% CI = −10.7 to 5.1) and KOOS function of −2.7 (−10.6 to 5.0).

Conclusion

Over a period of 2- and 4-weeks follow-up no significant difference in daily measured knee pain severity was found between primary care patients with knee osteoarthritis taking paracetamol or diclofenac. Also, over a period of 12-weeks follow-up no significant differences were found regarding KOOS pain and KOOS function between both groups. Patients more frequently reported minor adverse events after taking diclofenac (64%) than paracetamol (46%).     

Differential effects of nitric oxide on erythroid and myeloid colony growth from CD34+ human bone marrow cells

Nitric oxide (NO) is a reactive molecule with numerous physiologic and pathophysiologic roles affecting the nervous, cardiovascular, and immune systems. In previous work, we have demonstrated that NO inhibits the growth and induces the monocytic differentiation of cells of the HL- 60 cell line. We have also demonstrated that NO inhibits the growth of acute nonlymphocytic leukemia cells freshly isolated from untreated patients and increases monocytic differentiation antigens in some. In the present work, we studied the effect of NO on the growth and differentiation of normal human bone marrow cells in vitro. Mononuclear cells isolated from human bone marrow were cultured in semisolid media and treated with the NO-donating agents sodium nitroprusside (SNP) or S- nitroso-acetyl penicillamine (SNAP) (0.25 to 1 mmol/L). Both agents decreased colony-forming unit-erythroid (CFU-E) and colony-forming unit- granulocyte macrophage (CFU-GM) formation by 34% to 100%. When CD34+ cells were examined, we noted that these cells responded to SNP and SNAP differently than did the mononuclear cells. At a concentration range of 0.25 to 1 mmol/L, SNP inhibited the growth of CFU-E by 30% to 75%. However, at the same concentration range, SNP increased the number of CFU-GM by up to 94%. At concentrations of 0.25 to 1 mmol/L, SNAP inhibited the growth of CFU-E by 33% to 100%. At a concentration of 0.25 mmol/L, SNAP did not affect CFU-GM. At higher concentrations, SNAP inhibited the growth of CFU-GM. Although SNP increased intracellular levels of cGMP in bone marrow cells, increasing cGMP in cells by addition of 8-Br-cGMP (a membrane permeable cGMP analogue) did not reproduce the observed NO effects on bone marrow colonies. These results demonstrate that NO can influence the growth and differentiation of normal human bone marrow cells. NO (generated in the bone marrow microenvironment) may play an important role modulating the growth and differentiation of bone marrow cells in vivo.     

Protein N-myristoylation in Escherichia coli: reconstitution of a eukaryotic protein modification in bacteria.

Protein N-myristoylation refers to the covalent attachment of a myristoyl group (C14:0), via amide linkage, to the NH2-terminal glycine residue of certain cellular and viral proteins. Myristoyl-CoA:protein N-myristoyltransferase (NMT) catalyzes this cotranslational modification. We have developed a system for studying the substrate requirements and biological effects of protein N-myristoylation as well as NMT structure-activity relationships. Expression of the yeast NMT1 gene in Escherichia coli, a bacterium that has no endogenous NMT activity, results in production of the intact 53-kDa NMT polypeptide as well as a truncated polypeptide derived from proteolytic removal of its NH2-terminal 39 amino acids. Each E. coli-synthesized NMT species has fatty acid and peptide substrate specificities that are indistinguishable from those of NMT recovered from Saccharomyces cerevisiae, suggesting that the NH2-terminal domain of this enzyme is not required for its catalytic activity. By using a dual plasmid system, N-myristoylation of a mammalian protein was reconstituted in E. coli by simultaneous expression of the yeast NMT1 gene and a murine cDNA encoding the catalytic (C) subunit of cAMP-dependent protein kinase (PK-A). The fatty acid specificity of N-myristoylation was preserved in this system: [9,10(n)-3H]myristate but not [9,10(n)3H]palmitate was efficiently linked to Gly-1 of the C subunit. [13,14(n)-3H]10-Propoxydecanoic acid, a heteroatom-containing analog of myristic acid with reduced hydrophobicity but similar chain length, was an effective alternative substrate for NMT that also could be incorporated into the C subunit of PK-A. Such analogs have recently been shown to inhibit replication of certain retroviruses that depend upon linkage of a myristoyl group to their gag polyprotein precursors (e.g., the Pr55gag of human immunodeficiency virus type 1). A major advantage of the bacterial system over eukaryotic systems is the absence of endogenous NMT and substrates, providing a more straightforward way of preparing myristoylated, analog-substituted, and nonmyristoylated forms of a given protein for comparison of their structural and functional properties. The system should facilitate screening of enzyme inhibitors as well as alternative NMT fatty acid substrates for their ability to be incorporated into a specific target protein. Our experimental system may prove useful for recapitulating other eukaryotic protein modifications in E. coli so that structure-activity relationships of modifying enzymes and their substrates can be more readily assessed.     

Images of a Healthy Worksite: A Group-Randomized Trial for Worksite Weight Gain Prevention With Employee Participation in Intervention Design

Objectives. We assessed the effects of a worksite multiple-component intervention addressing diet and physical activity on employees’ mean body mass index (BMI) and the percentage of employees who were overweight or obese.Methods. This group-randomized trial (n = 3799) was conducted at 10 worksites in the northeastern United States. Worksites were paired and allocated into intervention and control conditions. Within- and between-groups changes in mean BMIs and in the percentage of overweight or obese employees were examined in a volunteer sample.Results. Within-group mean BMIs decreased by 0.54 kilograms per meter squared (P = .02) and 0.12 kilograms per meter squared (P = .73) at the intervention and control worksites, respectively, resulting in a difference in differences (DID) decrease of 0.42 kilograms per meter squared (P = .33). The within-group percentage of overweight or obese employees decreased by 3.7% (P = .07) at the intervention worksites and increased by 4.9% (P = .1) at the control worksites, resulting in a DID decline of 8.6% (P = .02).Conclusions. Our findings support a worksite population strategy that might eventually reduce the prevalence of overweight and obesity by minimizing environmental exposures to calorically dense foods and increasing exposures to opportunities for energy expenditure within worksite settings.Sixty-eight percent of adults residing in the United States are overweight or obese,1 and these conditions affect more than 1.4 billion adults worldwide.2 Traditional obesity control strategies, which have focused on changing diet and physical activity (PA) behaviors, provide significant individual benefits3 but are considered insufficient to reduce population disease burdens,4,5 for which broad, population-based approaches are needed.6 In addition to individual biology and behaviors, the physical, social, and cultural environment appears to contribute to the upward trend in population estimates of overweight and obesity7,8 by facilitating high-energy, low-nutrient diets and reducing the need to be physically active to perform activities of daily life.9Worksites are feasible self-contained environments with established communication systems in which interventions manipulating the food and PA environment and the social marketing of lifestyle changes can be implemented. Given that 58.4% of the US population aged 16 years or older is employed,10 worksite interventions have the potential to reach large number of adults11 and can foster the participation of employees in project development and sustainability.12–14 Moreover, participatory worksite interventions address workers’ needs, priorities, and interests and allow strategies to be adapted to the realities of individual sites.13 There is also a business case for weight control programs. In comparison with their nonobese counterparts, overweight and obese employees have higher absenteeism rates, have more work limitations, and are less productive.15–18With these issues in mind, the National Heart, Lung, and Blood Institute developed the Obesity Prevention in the Worksite initiative, a population-based approach to promoting behavioral change through environmental interventions that address prevention and control of weight gain.19 Prior to this initiative, worksite trials were either limited scope interventions, targeting a few aspects of the food or PA environment,9,20–23 or broader scope efforts simultaneously targeting risk factors for cardiovascular disease and cancer (e.g., smoking, diet).24–28 In addition, few studies addressed environmental influences related to excessive weight gain.Here we report the results of Images of a Healthy Worksite, one of the studies that is part of the Obesity Prevention in the Worksite initiative; this comprehensive nutrition and PA intervention was designed to promote healthy lifestyles and to stop the shift to the right of the population body mass index (BMI) curve. In this study, worksites were designated to receive an environmental intervention, and employees participated in intervention design. We hypothesized that mean BMIs among employees at the intervention worksites and the percentages of employees who were overweight or obese would not increase over a 2-year period or would increase less than at control worksites.