Differentiation Dependent Activation of the Myelin Genes In Purified Oligodendrocytes is Highly Resistant to Hypoglycemia

We have previously demonstrated that the developmental upregulation of myelin-specific genes in mixed glial cultures is strongly attenuated by hypoglycemia. The present study was designed to evaluate the effect of hypoglycemia on differentiation-dependent upregulation of myelin genes in purified oligodendrocyte cultures. The expression of major myelin protein genes, i.e., proteolipid protein (PLP), basic protein (BP) and myelin associated glycoprotein (MAG) were monitored by Northern blot analysis. In control cultures maintained at 6 mg/ml of glucose, the expression of all the genes upregulated rapidly, and plateaued at approximately day 4. A similar pattern of differentiation-dependent upregulation was observed for the gene encoding a lipogenic enzyme, i.e., malic enzyme (ME). In contrast to mixed glial cultures, however, this developmental gene upregulation was not significantly affected by severe hypoglycemia (approximately 0.02 mg/ml). The results indicate that the effect of glucose deprivation on oligodendrocyte genes observed in mixed glial cultures is mediated by other cells. The upregulation of the genes in differentiating oligodendrocytes was accompanied by the production of myelin-related membrane that was isolated by density gradient fractionation. In contrast to the effect on gene expression, this anabolic activity was highly dependent on glucose, as seen from a profound suppression by severe hypoglycemia.     

A comparison of several agents with two delivery systems for the prevention of airway narrowing induced by nebulised pentamidine isethionate

Bronchial narrowing is the major side effect of inhaled nebulised pentamidine isethionate, used for the prophylaxis and treatment of Pneumocystis carinii pneumonia. Several agents and delivery systems were assessed for prophylaxis of bronchial narrowing in HIV-positive males receiving regular nebulised pentamidine isethionate. In a previous study we found the mean maximum fall in FEV1 with nebulised pentamidine alone to be 21%. FEV1 was measured before and after inhaling nebulised pentamidine, preceded by one of the following bronchodilator/immunoregulatory agents: Terbutaline metered dose inhaler (500 micrograms), nebulised salbutamol (5 mg), nebulised ipratropium bromide (500 micrograms), nebulised sodium cromoglycate (20 mg), and nedocromil sodium metered dose inhaler (4 mg). Each agent was administered once only to ten different subjects. Nebulised salbutamol gave most effective prophylaxis against bronchial narrowing induced by nebulised pentamidine (mean maximum fall in FEV1 = 5% vs. 21%, P less than 0.001). Terbutaline given by metered dose inhaler was significantly less effective than high dose terbutaline (10 mg) given by nebuliser, demonstrated in the previous study (mean maximum fall in FEV1 = 14% vs. 6%, P less than 0.05). Mean maximum falls in FEV1 for ipratropium bromide, sodium cromoglycate and nedocromil sodium were 16, 17 and 16%, respectively. High dose beta 2-agonists administered by nebuliser give more effective prophylaxis against nebulised pentamidine-induced bronchial narrowing than either lower doses given by metered dose inhaler, anticholinergics or immunoregulatory drugs.     

Variations in Staff Characteristics, Programmes and Recruitment Practices among Halfway Houses for Problem Drinkers

In a sample of halfway houses for problem drinkers those with staff oriented to Alcoholics Anonymous tended to recruit residents less involved in skid-row than houses whose staff were not oriented to A.A. In general, however, staff ideologies and house programmes were not clearly related to the characteristics of the residents recruited. Overall retention was unrelated to staff ideology or the intensity of the in-house programme. Residents less involved in skid-row, however, tended to slay longer in houses with well articulated, structured programmes.     

The Composite Severity Score for Lumbar Spine MRI: a Metric of Cumulative Degenerative Disease Predicts Time Spent on Interpretation and Reporting

Conventional measures of radiologist efficiency, such as the relative value unit, fail to account for variations in the complexity and difficulty of a given study. For lumbar spine MRI (LMRI), an ideal performance metric should account for the global severity of lumbar degenerative disease (LSDD) which may influence reporting time (RT), thereby affecting clinical productivity. This study aims to derive a global LSDD metric and estimate its effect on RT. A 10-year archive of LMRI reports comprising 13,388 exams was reviewed. Objective reporting timestamps were used to calculate RT. A natural language processing (NLP) tool was used to extract radiologist-assigned stenosis severity using a 6-point scale (0?=?“normal” to 5?=?“severe”) at each lumbar level. The composite severity score (CSS) was calculated as the sum of each of 18 stenosis grades. The predictive values of CSS, sex, age, radiologist identity, and referring service on RT were examined with multiple regression models. The NLP tool accurately classified LSDD in 94.8% of cases in a validation set. The CSS increased with patient age and differed between men and women. In a univariable model, CSS was a significant predictor of mean RT (R²?=?0.38, p?<?0.001) and independent predictor of mean RT (p?<?0.001) controlling for patient sex, patient age, service location, and interpreting radiologist. The predictive strength of CSS was stronger for the low CSS range (CSS?=?0–25, R²?=?0.83, p?<?0.001) compared to higher CSS values (CSS?>?25, R²?=?0.15, p?=?0.05). Individual radiologist study volume was negatively correlated with mean RT (Pearson’s R?=????0.35, p?<?0.001). The composite severity score predicts radiologist reporting efficiency in LMRI, providing a quantitative measure of case complexity which may be useful for workflow planning and performance evaluation.

     

Membrane shape as a reporter for applied forces

Recent advances have enabled 3-dimensional reconstructions of biological structures in vivo, ranging in size and complexity from single proteins to multicellular structures. In particular, tomography and confocal microscopy have been exploited to capture detailed 3-dimensional conformations of membranes in cellular processes ranging from viral budding and organelle maintenance to phagocytosis. Despite the wealth of membrane structures available, there is as yet no generic, quantitative method for their interpretation. We propose that by modeling these observed biomembrane shapes as fluid lipid bilayers in mechanical equilibrium, the externally applied forces as well as the pressure, tension, and spontaneous curvature can be computed directly from the shape alone. To illustrate the potential power of this technique, we apply an axial force with optical tweezers to vesicles and explicitly demonstrate that the applied force is equal to the force computed from the membrane conformation.