Vesicle movement in rat hepatocytes is reduced by ethanol exposure: Alterations in microtubule-based motor enzymes

BACKGROUND & AIMS: Ethanol is known to alter vesicle-mediated protein trafficking in hepatocytes by undefined mechanisms. In this study, the effects of long- and short-term ethanol exposure on vesicle movements were measured in isolated hepatocytes, and alterations in the function of the microtubule-associated motor enzymes dynamin, kinesin, and dynein, which are believed to support the transport and/or budding of vesicles along microtubules, were tested. METHODS: Vesicular movements in isolated hepatocytes exposed to short- and long-term ethanol treatment were measured. Motor adenosine triphosphatase activities and their association with specific membrane organelles were assessed in response to long-term administration of ethanol in vivo or acetaldehyde in vitro. RESULTS: Hepatocytes exposed to short- or long-term ethanol treatment showed a significant reduction in the number of motile vesicles. No alterations in the levels of motor messenger RNA, protein, or enzymatic activity were observed. Interestingly, ethanol had no effect on the association of dynein and kinesin with membranes, whereas there was a significant increase in the amount of dynamin associated specifically with Golgi membranes. CONCLUSIONS: Long- and short-term ethanol exposure markedly reduces hepatocellular vesicle transport by a mechanism apparently independent of any alteration in the enzymatic activity of molecular motors, possibly involving a change in the function of dynamin. (Gastroenterology 1997 Dec;113(6):1938-48)     

Specific receptors for phorbol diesters on freshly isolated human myeloid and lymphoid leukemia cells: comparable binding characteristics despite different cellular responses

Freshly isolated human leukemia cells have been shown in the past to display varying in vitro responses to phorbol diesters, depending on their cell type. Specific receptors for the phorbol diesters have been demonstrated on numerous different cells. This study was designed to characterize the receptors for phorbol diesters on leukemia cells freshly isolated from patients with different kinds of leukemia and to determine if differences in binding characteristics for tritium-labeled phorbol 12,13-dibutyrate (3H-PDBu) accounted for the different cellular responses elicited in vitro by phorbol diesters. Cells from 26 patients with different kinds of leukemia were studied. PDBu or phorbol 12- myristate 13-acetate (PMA) caused cells from patients with acute myeloblastic leukemia (AML), acute promyelocytic (APML), acute myelomonocytic (AMML), acute monocytic (AMoL), acute erythroleukemia (AEL), chronic myelocytic leukemia (CML) in blast crisis (myeloid), acute undifferentiated leukemia (AUL), and hairy cell leukemia (HCL) (n = 15) to adhere to plastic and spread. However, they caused no adherence or spreading and only slight aggregation of cells from patients with acute lymphocytic leukemia (ALL), chronic lymphocytic leukemia (CLL), or CML-blast crisis (lymphoid) (n = 11). All leukemia cells studied, irrespective of cellular type, displayed specific receptors for 3H-PDBu. The time courses for binding by all leukemia types were similar, with peak binding at 5-10 min at 37 degrees C and 120 min at 4 degrees C. The binding affinities were similar for patients with ALL (96 +/- 32 nM, n = 4), CLL (126 +/- 32 nM, n = 6), and acute nonlymphoid leukemia (73 +/- 14 nM, n = 11). Likewise, the numbers of specific binding sites/cell were comparable for the patients with ALL (6.2 +/- 1.3 X 10(5) sites/cell, n = 4), CLL (5.0 +/- 2.0 X 10(5) sites/cell, n = 6), and acute nonlymphoid leukemia (4.4 +/- 1.9 X 10(5) sites/cell, n = 11). Thus, the differing responses to phorbol diesters of various types of freshly isolated leukemia cells appear to be due to differences other than initial ligand-receptor binding.     

Body composition in systemic lupus erythematosus

The objectives were to determine the body composition, and the effects of disease and corticosteroid therapy on body composition, in a population of female patients with systemic lupus erythematosus (SLE). All female SLE patients managed through a single centre were invited to participate in a cross-sectional study of body composition. Data were collected by standardized interview and examination, and review of medical records. Body composition was assessed by dual-energy X-ray absorptiometry (DXA). Eighty-two subjects were evaluated, 30 of whom were post-menopausal. Univariate linear regression analysis revealed a significant association of reduced fat-free mass with SLE severity [as measured by the Systemic Lupus International Collaborative Clinics (SLICC)] (P = 0.020), a history of corticosteroid exposure (P = 0.043) and age (P = 0.048). Reduced total body bone mineral density (BMD) was also significantly associated with SLICC (P < 0.001) and corticosteroid exposure (P = 0.017), and with age (P < 0.001), post-menopausal status (P = 0.003) and the duration of menopause (P < 0.001). Stepwise multiple linear regression analysis revealed a significant association between fat-free mass and total body, lumbar spine and femoral neck BMD (P = 0.007, P = 0.025, P = 0.003, respectively). Fat mass was significantly associated only with lumbar spine BMD (P = 0.008). In this SLE population, disease severity and corticosteroid exposure were independently associated with a negative effect both on total body BMD and on fat-free mass. Fat-free mass was a significant predictor of lumbar spine, femoral neck and total body BMD.      

Screening blood donors for gastrointestinal illness: a strategy to eliminate carriers of Yersinia enterocolitica

Recent reports of fatal transfusion-associated Yersinia enterocolitica sepsis prompted a study of the feasibility of adding a question to the routine donor health history as a method of reducing this risk. In three American Red Cross blood centers, 11,323 donors were asked one of two questions about gastrointestinal symptoms during their health history screenings. Affirmative responses were obtained from 0.6 or 4.0 percent of the donors, depending on how the question was asked. In one center, more than 6 percent of donors gave affirmative answers. The efficacy of asking a relatively simple question about gastrointestinal symptoms as a way of preventing Y. enterocolitica should be evaluated further, because relatively large numbers of donors may respond affirmatively. Other methods of reducing the risk of transfusion-associated Y. enterocolitica infection should be pursued.