Interleukin-3, GM-CSF, and TPA induce distinct phosphorylation events in an interleukin 3-dependent multipotential cell line

The mechanism of action of the hemopoietic growth factor, murine interleukin-3 (mIL-3), was investigated using an mIL-3-dependent multipotential hematopoietic cell line, B6SUtA1. Murine granulocyte- macrophage colony-stimulating factor (mGM-CSF) was as potent as mIL-3 in stimulating these cells. In addition, sodium orthovanadate, an inhibitor of phosphotyrosine phosphatase, and 12-O-tetradecanoyl- phorbol-13-acetate (TPA), a known activator of protein kinase C, also stimulated DNA synthesis in these cells, suggesting that protein phosphorylation might be involved in the mechanism of action of mIL-3 and mGM-CSF. To assess this possibility, intact B6SUtA1 cells exposed for brief periods to mIL-3, mGM-CSF, and TPA were analyzed for changes in phosphorylation patterns using metabolic 32P-labeling and antibodies to phosphotyrosine. Both mIL-3 and mGM-CSF induced the serine-specific phosphorylation of a 68-Kd cytosolic protein, whereas all three agents stimulated the serine-specific phosphorylation of a 68-Kd membrane protein. Furthermore, mIL-3 stimulated tyrosine phosphorylation of the 68-Kd membrane protein, as well as of 140-, 90-, 55, and 40-Kd proteins. The 90-Kd protein was also tyrosine phosphorylated in response to mGM-CSF. These phosphotyrosine containing proteins were not detected in TPA-treated cells. These results indicate that protein phosphorylations on tyrosine and serine residues occur in B6SUtA1 cells following short-term incubation with mIL-3 or mGM-CSF and that most of these phosphorylation events are mediated by kinases other than protein kinase C (PkC).     

Targeted disruption of the IA-2beta gene causes glucose intolerance and impairs insulin secretion but does not prevent the development of diabetes in NOD mice

Insulinoma-associated protein (IA)-2beta, also known as phogrin, is an enzymatically inactive member of the transmembrane protein tyrosine phosphatase family and is located in dense-core secretory vesicles. In patients with type 1 diabetes, autoantibodies to IA-2beta appear years before the development of clinical disease. The genomic structure and function of IA-2beta, however, is not known. In the present study, we determined the genomic structure of IA-2beta and found that both human and mouse IA-2beta consist of 23 exons and span approximately 1,000 and 800 kb, respectively. With this information, we prepared a targeting construct and inactivated the mouse IA-2beta gene as demonstrated by lack of IA-2beta mRNA and protein expression. The IA-2beta(-/-) mice, in contrast to wild-type controls, showed mild glucose intolerance and impaired glucose-stimulated insulin secretion. Knockout of the IA-2beta gene in NOD mice, the most widely studied animal model for human type 1 diabetes, failed to prevent the development of cyclophosphamide-induced diabetes. We conclude that IA-2beta is involved in insulin secretion, but despite its importance as a major autoantigen in human type 1 diabetes, it is not required for the development of diabetes in NOD mice.     

Identification of an oncogenic form of the thrombopoietin receptor MPL using retrovirus-mediated gene transfer

Thrombopoietin and its receptor (MPL) are important regulators of megakaryopoiesis. We have identified an activating mutation of MPL using a combination of a retrovirus-mediated gene transfer and polymerase chain reaction-driven random mutagenesis. This point mutation causes a single amino acid substitution from Ser498 to Asn498 in the transmembrane region and abrogates factor-dependency of all interleukin-3-dependent cell lines tested. Murine interleukin-3- dependent Ba/F3 cells expressing the mutated but not the normal form of MPL were tumorigenic when transduced into syngeneic mice. Analysis of intracellular signaling pathways indicated that the mutant MPL protein constitutively activated two distinct signaling pathways, SHC-Raf-MAPK and JAK2-STAT3/STAT5.     

Safety and Effectiveness of Transvenous Lead Extraction in Octogenarians

Transvenous Lead Extraction . Introduction: As the population ages, the number of elderly patients with implantable cardiac devices referred for transvenous lead extraction will dramatically increase in Western countries. The safety and effectiveness of lead extraction in elderly patients has not been well evaluated. We report the safety and effectiveness of transvenous lead extraction in octogenarians. Methods and Results: From January 2005 to January 2011, we reviewed data from consecutive patients ≥ 80 years referred to our institutions for transvenous lead extraction because of cardiac device infection or lead malfunction. Clinical characteristics, procedural features, and periprocedural major and minor complications were compared between octogenarians and younger patients. Out of 849 patients undergoing lead extraction in the participating institutions during the study period, 150 (18%) patients were octogenarians (mean age 84 years; range 80–96; 64% males). A significantly higher percentage of octogenarians presented with chronic renal failure (55% vs 26%; P < 0.001), history of malignancy (22% vs 6%; P < 0.001), and chronic obstructive pulmonary disease (46% vs 19%; P < 0.001). Complete lead extraction rates were similar in the 2 age groups (97% in octogenarians vs 96% in patients <80 years; P = 0.39). Periprocedural death occurred in 2 (1.3%) patients ≥80 years and in 5 (0.72%) patients <80 years (P = 0.45 for comparison). No differences in terms of other periprocedural major and minor complications were found between the 2 age groups. Conclusion: Despite presenting with a significantly higher rate of comorbidities, transvenous lead extraction can be performed safely and successfully in octogenarians. (J Cardiovasc Electrophysiol, Vol. 23 pp. 1103‐1108, October 2012)     

Factors Affecting Job Satisfaction and Their Correlation with Educational Standards among Dental Assistants

A disparity exists in the educational qualifications of dental assistants working in various public and private institutions in Riyadh, Saudi Arabia. The aim of this study was to assess the influence of professional and personal characteristics on job satisfaction among dental assistants. A cross-sectional survey was performed among dental assistants using a 24-item self-administered questionnaire. Multinomial logistic regression was used to assess the relationship between overall job satisfaction and other variables. The overall response rate was 72.1%. Factor analysis suggested that five underlying factors were related to job satisfaction. The mean score for overall job satisfaction was 3.86 (satisfied) out of 5. Among the work environment factors, the highest mean score, 4.26 (satisfied), was obtained for quality of service, and the lowest mean score, 2.78 (neutral), was obtained for the perception of income. The income and general prospects of the profession was significantly associated with overall job satisfaction. This study suggests that for dental assistants, professional and personal life, quality of service, perception of income and prestige and self-respect are important factors for job satisfaction. Despite differences in professional formation standards, in general, the study participants were considerably satisfied with their jobs.     

Father involvement with three-to-four-year olds at home: giving fathers a chance

This study examined fathers' perceptions regarding their home-based activities (HBA) and the influence of fathers' demographic characteristics on their perceptions and practices at home. A total of 396 fathers completed a survey questionnaire describing their demographic information, perceptions and their practices regarding their involvement in HBA. Results indicated that fathers have moderate level of practice concerning their HBA, yet they have low perception of their actual practice at HBA. In addition, there was a statistical significance in HBA due to fathers' age, educational level and specialisation which had an influence on their perceptions as well. Recommendations and implications of future research were discussed.