Acidic pH of the lateral intercellular spaces of MDCK cells cultured on permeable supports

The pH of the lateral intercellular space (LIS) of Madin-Darby canine kidney (MDCK) cell monolayers grown on permeable supports was investigated by microspectrofluorimetry using BCECF (2',7'-bis(carboxyethyl)-5,6-carboxyfluorescein). The permeability of the support was selectively reduced by growing Zn-Al-silicate crystals inside its pores. The diffusion of BCECF across the filter was sufficiently retarded to allow measurements of fluorescence in the LIS. The LIS pH and intracellular pH of the cells surrounding them were determined in HEPES-buffered solutions. When the perfusate pH was 7.4, the LIS pH was more acidic (7.06 +/- 0.02) and equaled the cytoplasmic pH (7.08 +/- 0.05). When perfusate was changed to pH 7.0 or 7.8, the LIS changed linearly by about half the magnitude of the perfusate pH. Intracellular pH followed LIS pH variations between perfusate pH 7.0 and 7.4 but was significantly higher when perfusate pH was 7.8. Tight junctional H+ permeability was undetectably low. The low steady-state pH in the LIS was not altered by inhibitors of acid transport or low temperature. Rapid perturbations of pH in the LIS showed that protons were not immobilized in the LIS. The acidic microenvironment within the LIS may be the result of buffering by the cell surface proteins.     

Fibroblast growth factor-2 alters the effect of eroding polylactide-polyglycolide on osteogenesis in the bone chamber

The effects of recombinant human fibroblast growth factor-2 (rhFGF-2) in the presence of eroding 50:50 poly(DL-lactide-co-glycolide) (PDLLG) on acute bone healing were studied in the optical bone chamber (BCI). BCIs were loaded with disks of PDLLG surrounded by one of four rhFGF-2 doses. Fifty-two female rabbit right tibias were implanted. Commencing the third week post implantation (W3) healing in the BCI compartment was observed weekly, using intravital microscopy, until W8. The doses were: unloaded, loaded with polymer only, and polymer plus 0.5, 1.0, and 10 microg rhFGF-2. Videotaped and photographed bone images were measured and analyzed using a frame-grabber digitizing system. Comparison with controls revealed that ossification rates were significantly above normal in rabbits loaded with polymer plus any of the rhFGF-2 doses. Comparison with polymer-only BCIs showed that PDLLG plus any of the three rhFGF-2 doses was linked with ossification rates significantly higher than baseline. The results indicated that FGF-2 in the dose range studied effectively can overcome the retarding effects of eroding polymer on ossification that has been reported by this laboratory. Interpretation of the retarding effects of the polymer disks, although consistent with previously studied washer-shaped devices of the same material, was complicated by a difference in erosion rate. This result supports the notion that erodible device geometry is a major factor in determining biocompatibility and must be considered in the design of carriers. Accordingly, programming of dose specificity for delivering a given polypeptide cytokine to a given host site must allow for the inhibitory effects of an eroding carrier and the influence of device geometry on these effects and erosion.     

Comparison of autologous bone marrow transplantation and intensive chemotherapy as postremission therapy in adult acute myeloid leukemia. The Groupe Ouest Est Leucémies Aigu?s Myéloblastiques (GOELAM)

Three intensive consolidation strategies are currently proposed to younger adults with acute myeloid leukemia (AML) in first complete remission (CR): allogeneic or autologous bone marrow transplantation (BMT) and intensive consolidation chemotherapy (ICC). Patients aged 15 to 50 years with de novo AML received an induction treatment with 7 days of cytarabine and either idarubicin or rubidazone. After achievement of a CR, patients up to the age of 40 and having an HLA-identical sibling were assigned to undergo an allogeneic BMT. All the other patients received a first course of ICC with high-dose cytarabine and the same anthracycline as for induction. They were then randomly assigned to either receive a second course of ICC with amsacrine and etoposide or a combination of busulfan and cyclosphosphamide followed by an unpurged autologous BMT. Of 517 eligible patients, 367 had a CR, but only 219 (59.5%) actually received the planned intensive postremission treatment (73 allogeneic BMT, 75 autologous BMT, and 71 ICC). With a median follow-up of 62 months, the 4-year disease-free survival (DFS) of the 367 patients in CR was 39.5%. The 4-year overall survival (OS) of the 517 eligible patients was 40.5%. In multivariate analysis, DFS and OS were influenced only by the initial white blood cell count and by the French-American-British classification. The type of postremission therapy had no significant impact on the outcome. There was no difference in the 4-year DFS and OS between 88 patients for whom an allogeneic BMT was scheduled (respectively, 44% and 53%) and 134 patients of the same age category and without an HLA-identical sibling (respectively, 38% and 53%). Similarly, there was no difference in the outcome between autologous BMT and ICC. The 4-year DFS was 44% for the 86 patients randomly assigned to autologous BMT and 40% for the 78 patients assigned to ICC (P = .41). The 4-year OS was similar in the two groups (50% v 54.5%, P = .72). The median duration of hospitalization and thrombocytopenia were longer after autologous BMT (39 v 32 days, P = .006, and 109.5 v 18.5 days, P = .0001, respectively). After a first course of ICC, a second course of chemotherapy is less myelotoxic than an unpurged autologous BMT but yields comparable DFS and OS rates.     

Monitoring of polyethylene wear in nonmetal-backed acetubular cups by digitized anteroposterior pelvic radiography

The aim of this study was to assess polyethylene wear in a total hip prosthesis by digitized radiography of the whole pelvis in the anteroposterior (AP) plane. The three-dimensional (3-D) pose of the nonmetal-backed acetubular cup, materialized by its metal ring and the femoral head made of metal or ceramic, was estimated using iterative algebraic algorithms with inner bias correction and bootstrapping for variance reduction. Points of interest were obtained by maximizing the correlation between sampled density profiles and 3-D geometric models degraded by the modulation transfer function (MTF) of the radiographic system and the film scanner. The error in the maximal correlation estimate were inferred from noise power spectra (NPS) and allowed the calculation of the point covariance matrix. Both NPS and MTF were modeled for each stage and estimated using least-square fitting of the overall NPS model to the autospectral density function calculated in stationary regions. Comparison of the radiographic time series was made possible by the high accuracy level and 3-D matching from the cup orientation. The feasibility of the full 3-D measurement, the assumption of negligible lateral wear and its influence on AP wear are discussed on simulated and real radiographic data.     

Neuronal spike activity in the nucleus accumbens of behaving rats during ethanol self-administration

Many lines of evidence support the importance of the nucleus accumbens (NAC) for ethanol-reinforced behavior. The nature of the neuronal activity that occurs in this region during ethanol self-administration is not known. We recorded from ensembles of single-units primarily located within the shell of the NAC during operant responding for oral ethanol solutions by well-trained rats. Of 90 units recorded from seven sessions from seven rats, 41 (46%) did not exhibit significant changes in relation to the experimental events. Of the 49 units (54%) that did exhibit significant phasic changes, alterations in firing rate occurred in relation to the following experimental events: operant response (63%), tone stimulus (20%), and ethanol delivery (63%). In addition, changes in spike activity during the intervals between the three experimental events were noted in 33% of the units. Most units (55% of responsive units) responded to multiple experimental events. Thus different but overlapping populations of neurons in the NAC represent each event that occurs along the temporal dimension of a single trial performed to obtain ethanol reward. The data suggest that the NAC plays a crucial role in linking together conditioned and unconditioned internal and external stimuli with motor plans to allow for ethanol-seeking behavior to occur.     

Cell-mediated autoimmunity in paraneoplastic neurological syndromes with anti-Hu antibodies

The authors investigated the association of caffeinated coffee, decaffeinated coffee, and tea with myocardial infarction in a study of 340 cases and age-, sex-, and community-matched controls. The odds ratio for drinking > or = 4 cups/day of caffeinated coffee versus drinking < or = 1 cup/week was 0.84 (95% confidence interval (CI) 0.49-1.42) after adjustment for coronary risk factors (1 cup = 237 ml). The odds ratio for drinking > 1 cup/day of decaffeinated coffee versus nondrinkers was 1.25 (95% CI 0.76-2.04). For tea, the odds ratio for drinking > or = 1 cup/day versus nondrinkers was 0.56 (95% CI 0.35-0.90). In these data, only tea was associated with a lower risk of myocardial infarction.     

Haemolysis complicating acute viral hepatitis in patients with normal or deficient glucose-6-phosphate dehydrogenase activity

Haemolytic anaemia as a complication of acute hepatitis has been reported in up to 23% of patients. However, the incidence may rise up to 70-87% in patients who have glucose-6-phosphate dehydrogenase (G6PD) deficiency. Massive intravascular haemolysis with renal failure, hepatic encephalopathy and even death have been reported. In our retrospective study of patients with acute viral hepatitis, the overall incidence of acute haemolysis was 4% (17/434). Only 53% (9/17) of them had G6PD deficiency. Patients with acute haemolysis had a significantly higher peak bilirubin level and required more prolonged hospitalization. Since hepatitis A virus vaccination, unlike hepatitis B virus vaccination, is not yet recommended for routine immunization, we suggest subjects who are G6PD-deficient should be vaccinated against hepatitis A. In endemic areas of hepatitis A virus infection, universal immunization remains the definitive answer.     

Age-dependent tetrahydrothiophenium ion formation in young children and adults receiving high-dose busulfan

Busulfan, a bifunctional alkylating agent, is a mainstay of myeloablative preparative regimens before hematopoietic stem cell transplantation. The apparent oral clearance of busulfan expressed relative to body surface area is 2-3-fold higher in children 1-4 years old than it is in adults. The first step in busulfan elimination is the formation of a tetrahydrothiophenium ion (THT+) in a glutathione S-transferase-catalyzed reaction. We present computer simulations that demonstrate that the ratio of the AUC of THT+ to that of busulfan over 6 h [(AUC(THT+)/AUC(BU))(0-->6)] is highly correlated (r2 = 0.805) with the determinants of THT+ formation and is virtually independent of the determinants of its elimination (r2 = 0.0201). We compared (AUC(THT+)/AUC(BU))(0-->6) determined in 14 children (0.5-4 years) to that of 11 adults (12-54 years) and found a 1.5-fold elevation in the area ratio (P = 0.0098) and a similarly significant increase in busulfan apparent oral clearance expressed relative to body surface area (P = 0.042). The only common explanation for the elevated busulfan apparent oral clearance and (AUC(THT+)/AUC(BU))(0-->6) is an enhanced ability of children to metabolize busulfan through glutathione conjugation.