Using stereology and immunoelectron microscopy we examined the pathway of Golgi cluster formation during treatment with the phosphatase inhibitor okadaic acid. During the first hour the Golgi stack of suspension HeLa cells lost 90% of its membrane without appreciable reduction in the number of cisternae. During this time clusters of tubules and vesicles (Golgi clusters) appeared and these contained only a fraction of the Golgi membrane present in untreated cells. Despite the overall reduction in membrane the total amount of immunolabeling for galactosyltransferase over the Golgi clusters of a typical cell was maintained, indicating that galactosyltransferase had been retained in Golgi membranes. The observation that, after 40 min okadaic acid treatment, labeling density for galactosyltransferase within trans Golgi cisternae increased 1.6-fold (n = 3, CE 10%) suggests that membrane loss from trans cisternae was selective. Careful evaluation of immunolabeled clusters showed that most of the galactosyltransferase labeling was located over complex tubular profiles and not vesicular profiles. Tubular structures were also observed during disassembly and these were found both connected to disassembling cisternae and within forming Golgi clusters, indicating that they were intermediates in cluster formation. We also investigated the role of vesicular transport in cluster formation. During disassembly we found no accumulation of COP-coated buds and vesicles over Golgi membrane. However, aluminium fluoride, previously found to arrest transport in the Golgi stack, completely inhibited membrane depletion and stack disassembly. Taken together, our results indicate that during Golgi cluster formation, membrane leaves the Golgi but galactosyltransferase is retained within a tubular reticulum which is a direct descendant of trans-Golgi cisternae. Membrane depletion may require ongoing vesicular transport and we postulate that it arises because of an imbalance in membrane traffic into and out of the Golgi apparatus.

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PubMedDate not supplied

Differentiation of cultured mice bone marrow into osteoblast-like cells results in acquisition of sex-specific responsiveness to gonadal steroids.

We have previously demonstrated that mouse skeletal tissue, rat bone as well as rat or human derived bone cells in culture, show a sex-specific response to gonadal steroids in stimulation of the specific activity of the BB isozyme of creatine kinase (CK). This response could be modified by manipulation of the endocrine environment during early postnatal development. Moreover, pretreatment with vitamin D up-regulated the sex-specific responsiveness and sensitivity to gonadal steroids. In the present study we examine the differentiation pattern into osteoblast-like cells using dexamethasone (DEX) and 1,25 dihydroxy vitamin D3 (1,25D) and their effect on the acquisition of responsiveness to gonadal steroids by the differentiated cells. Cultured femoral bone marrow in the presence of DEX or 1,25D or both, were examined for their response to gonadal steroids by measuring the specific activities of alkaline phosphatase (AP) and CK BB. The constitutive level of CK in both male- and female-derived bone cells was decreased by DEX, by 1,25D or by both, whereas the constitutive level of AP was increased by DEX while decreased by 1,25D or by both. Following incubation of the bone marrow cultures with DEX, treatment with estradiol 17beta (E2, 30 nM, 24 h) stimulated CK activity in female derived bone cells, with no effect of treatment with dihydrotestosterone (DHT, 300 nM). In contrast, in male derived bone cells, DHT but not E2 increased CK activity. This sex-specific response was also achieved upon culturing with 1,25D and was significantly augmented by culturing with both. No response to gonadal steroids was seen with undifferentiated bone marrow cells. All cultures responded to IGF-I when cultured with or without DEX and/or 1,25D but with no augmentation by 1,25D. Gonadal steroids increased AP to a much lesser extent; but enzyme activity decreased in the presence of 1,25D. IGF-I stimulated AP slightly with no effect of 1,25D. These findings suggest that manipulation of the hormonal milieu in early stages of differentiation sequence of osteoblast-like cells, determines the subsequent selective responsiveness of the developing bone tissue to gonadal steroids.

Animals↗

PubMedDate not supplied

Suppression of malaria infection by oxidant-sensitive host erythrocytes.

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Anemia↗

PubMedDate not supplied

Sustaining work redesign innovations through shared governance.

Organizational change, in the form of work redesign, is widespread in hospitals across the country. How can the resulting patient-focused care models be sustained when "sustaining" means continuously changing and improving? The authors describe one hospital's use of a multidisciplinary shared governance system to provide the structure and process support for the innovative changes initiated by work redesign.

Costs and Cost Analysis↗

PubMedDate not supplied

Role of a stroke data bank in evaluating cerebral infarction subtypes: patterns and outcome of 1,776 consecutive patients from the Besançon stroke registry.

UNLABELLED: The purpose of this study was to estimate the frequency of various risk factors, courses and outcome of infarct subtypes in a large hospital-based stroke registry. METHODS: From 1987 to 1994, 1,776 stroke patients with a first-ever infarction were included in the Besançon Stroke Registry. All patients were evaluated by a standard protocol (risk factors, stroke onset, stroke courses, clinical characteristics, neuroimaging, Doppler ultrasonography and cardiac investigations). Outcome was evaluated at 30 days using the Rankin scale. RESULTS: There were 1,012 men (mean age 67.2 +/- 13.7 years) and 764 women (mean age 71.4 +/- 15.6 years). At least two neuroimaging examinations were performed in 81.4% (n = 1,446) of the patients and an infarct was visible in 80.9% (n = 1,436). The second neuroimaging examination (CT or MRI) was performed after 8.2 +/- 1.6 days. 85.4% of patients were admitted on the first day of the stroke: 28.3% within 3 h and 48.4% within 6 h. In addition, stroke severity was well correlated with the short time interval between stroke onset and admission. Past medical history of hypertension was the major risk factor occurring in 57.5% of all types of infarction. While diabetes was more frequently found in small deep infarct, atrial fibrillation and history of heart failure were found in anterior circulation infarcts. The distribution of clinical presentations was conventional. Hemorrhagic transformation was found in 14.9% of the patients, especially in MCA and PCA infarcts. In all patients, logistic regression analysis determined independent predictive factors for death: clinical deterioration at the 48th hour (OR 7.5, 95% CI 4.9-11.3), initial loss of consciousness (OR 3. 3, 95% CI 2.1-4.9), age (OR 1.05, 95% CI 1.03-1.06), complete motor deficit (OR 2.6, 95% CI 1.7-3.8), history of heart failure (OR 1.9, 95% CI 1.3-3.0), lacunar syndrome (OR 0.25, 95% CI 0.10-0.60) and regressive stroke onset (OR 0.24, 95% CI 0.10-0.52). However, the outcome was clearly correlated with the infarct location. The in-hospital mortality rate was lowest in patients with small deep infarct (2.9%) or border zone infarcts (3.4%) and the highest in patients with total middle cerebral artery infarct (47.4%) or multiple infarcts (27.6%). CONCLUSION: Our registry appears to be a useful tool to understand the course and outcome of a large group of nonselected patients with subtypes of infarction. It can also help to analyze the influence of specific stroke management in the different categories of stroke types.

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