Effects of chronic run training on Na+-dependent Ca2+ efflux from rat left ventricular myocytes

The effects of endurance run training on Na+-dependent Ca2+ regulation in rat left ventricular myocytes were examined. Myocytes were isolated from sedentary and trained rats and loaded with fura 2. Contractile dynamics and fluorescence ratio transients were recorded during electrical pacing at 0.5 Hz, 2 mM extracellular Ca2+ concentration, and 29 degreesC. Resting and peak cytosolic Ca2+ concentration ([Ca2+]c) did not change with exercise training. However, resting and peak [Ca2+]c increased significantly in both groups during 5 min of continuous pacing, although diastolic [Ca2+]c in the trained group was less susceptible to this elevation of intracellular Ca2+. Run training also significantly reduced the rate of [Ca2+]c decay during relaxation. Myocytes were then exposed to 10 mM caffeine in the absence of external Na+ or Ca2+ to trigger sarcoplasmic reticular Ca2+ release and to suppress cellular Ca2+ efflux. This maneuver elicited an elevated steady-state [Ca2+]c. External Na+ was then added, and the rate of [Ca2+]c clearance was determined. Run training significantly reduced the rate of Na+-dependent clearance of [Ca2+]c during the caffeine-induced contractures. These data demonstrate that the removal of cytosolic Ca2+ was depressed with exercise training under these experimental conditions and may be specifically reflective of a training-induced decrease in the rate of cytosolic Ca2+ removal via Na+/Ca2+ exchange and/or in the amount of Ca2+ moved across the sarcolemma during a contraction.     

Phosphoinositide 3-kinase induces scattering and tubulogenesis in epithelial cells through a novel pathway

Hepatocyte growth factor/scatter factor (HGF/SF) treatment of the Madin-Darby canine kidney epithelial cell line causes scattering of cells grown in monolayer culture and the formation of branching tubules by cells grown in collagen gels. HGF/SF causes prolonged activation of both the mitogen-activated protein (MAP) kinase extracellular signal-regulated kinase 2 (ERK2) and the phosphoinositide 3-OH kinase (PI 3-kinase) target protein kinase B (PKB)/Akt; inhibition of either the MAP kinase pathway by the MAP kinase/ERK kinase inhibitor PD98059 or the PI 3-kinase pathway by LY294002 blocks HGF/SF induction of scattering, although in morphologically distinct ways. Expression of constitutively activated PI 3-kinase, Ras, or R-Ras will cause scattering, but activated Raf will not, indicating that activation of the MAP kinase pathway is not sufficient for this response. Downstream of PI 3-kinase, activated PKB/Akt and Rac are both unable to induce scattering, implicating a novel pathway. Scattering induced by Ras or PI 3-kinase is sensitive to PD98059, as well as to LY294002, suggesting that basal MAP kinase activity is required, but not sufficient, for the scattering response. Induction of MDCK cell tubulogenesis in collagen gels by HGF/SF is inhibited by PD98059; expression of activated Ras and Raf causes disorganized growth in this system, but activated PI 3-kinase or R-Ras causes branching tubule formation similar to that seen with HGF/SF treatment. These data indicate that multiple signaling pathways acting downstream of Met and Ras are needed for these morphological effects; scattering is induced primarily by the PI 3-kinase pathway, which acts through effectors other than PKB/Akt or Rac and requires at least basal MAP kinase function. Elevated PI 3-kinase activity induces tubulogenesis, but total inhibition and excess activation of the MAP kinase pathway both oppose this effect.     

Gustin from human parotid saliva is carbonic anhydrase VI

It has been found that yeast mutants deficient in cytosolic superoxide dismutase CuZnSOD are hypersensitive to ferrous iron. In contrast mutants that are deficient in catalases and cytochrome c peroxidase do not differ from the standard strain in this respect. These findings suggest that iron toxicity may depend on the redox status of the cell. They also shed light on the role of superoxide dismutases in preventing the toxic effects of oxygen.     

The gp200-MR6 molecule which is functionally associated with the IL-4 receptor modulates B cell phenotype and is a novel member of the human macrophage mannose receptor family

The human gp200-MR6 molecule has previously been shown to have either an antagonistic or agonistic effect on IL-4 function, demonstrated by inhibition of IL-4-induced proliferation of T cells or mimicking of IL-4-induced maturation of epithelium, respectively. We now show that gp200-MR6 ligation can also mimic IL-4 and have an anti-proliferative pro-maturational influence within the immune system, causing up-regulation of co-stimulatory molecules on B lymphocytes. Biochemical analysis and cDNA cloning reveal that gp200-MR6 belongs to the human macrophage mannose receptor family of multidomain molecules. It comprises 1722 amino acids in toto (mature protein, 1695 amino acids; signal sequence, 27 amino acids) organized into 12 external domains (an N-terminal cysteine-rich domain, a fibronectin type II domain and 10 C-type carbohydrate recognition domains), a transmembrane region and a small cytoplasmic C terminus (31 amino acids) containing a single tyrosine residue (Y1679), but no obvious kinase domain. Strong amino acid sequence identity (77%) suggests that gp200-MR6 is the human homologue of the murine DEC-205, indicating that this molecule has much wider functional activity than its classical endocytic role. We also show that the gp200-MR6 molecule is closely associated with tyrosine kinase activity; the link between gp200-MR6 and the IL-4 receptor may therefore be via intracellular signaling pathways, with multifunctionality residing in its extracellular multidomain structure.     

The use of Haemophilus influenzae type b-tetanus toxoid conjugate vaccine mixed with diphtheria-tetanus-pertussis vaccine in Gambian infants

In preparation for an efficacy trial of PRP-T Haemophilus influenzae type b conjugate vaccine, 251 Gambian infants were randomized to receive three doses of PRP-T and diphtheria-tetanus-pertussis (DTP) vaccines at 2, 3 and 4 months of age, either by separate injections, or combined in the same syringe. One month after the third dose, there was no difference between anti-PRP levels in those infants who received the vaccines separately (GMT 5.83 micrograms ml-1), and those who received the vaccines combined (GMT 5.57 micrograms ml-1). The proportions achieving levels of 1.0 microgram ml-1 were 89% and 92% in the "separate" and "combined" vaccine groups, respectively. There were no significant differences between groups in levels of antibody to diphtheria or tetanus. Geometric mean titres of antibody directed against pertussis antigens in the "separate" and "combined" groups were as follows: pertussis toxin 14.2 and 13.1 ELISA units (EU) ml-1; filamentous haemagglutinin 12.2 and 9.7 EU ml-1; pertactin 17.2 and 9.0 EU ml-1 (P < 0.05), fimbrial 2/3 antigens 449 and 364 EU ml-1. The combination of PRP-T and DTP in the syringe prior to administration is safe and immunogenic. The lower levels of anti-pertussis antibody are of unknown clinical significance.     

Plateletapheresis with a next generation blood cell separator

Baeyer-Villiger monooxygenases (BVMOs) are enzymes able to perform highly regio-plus steroselective nucleophilic and electrophilic biooxygenations on various substrates. The resultant chiral products (lactones and sulfoxides) can be valuable for the chemoenzymatic synthesis of a wide range of useful compounds. Recent studies have provided a number of alternative active-site models that attempt to explain the exquisite and unusual selectivity of BVMOs. This article reviews some of the established applications, and considers the merits of the various predictive models.     

Prospective, randomized trial of prolonged intracoronary urokinase infusion for chronic total occlusions in native coronary arteries

OBJECTIVES: The purpose of this study was to determine the safety and efficacy of three dosing regimens of intracoronary urokinase for facilitated angioplasty of chronic total native coronary artery occlusions. BACKGROUND: Percutaneous transluminal coronary angioplasty of chronically occluded (>3 months) native coronary arteries is associated with low initial success secondary to an inability to pass the guide wire beyond the occlusion. METHODS: Patients were enrolled if a chronic total occlusion >3 months old could not be crossed with standard angioplasty equipment. Of the 101 patients enrolled, 41 had successful guide wire passage and were excluded from urokinase treatment. The remaining 60 patients were randomized to receive one of three intracoronary dosing regimens of urokinase over 8 h (group A = 0.8 million U; group B = 1.6 million U; group C = 3.2 million U), and angioplasty was again attempted after completion of the urokinase infusion in 58 patients. RESULTS: Coronary angioplasty was successful in 32 patients (53%) (group A 52%, group B 50%, group C 59%, p = 0.86). This study had a 90% power to detect at least a 50% difference between dosing groups at alpha 0.05. Bleeding complications requiring blood transfusion did not differ significantly among the dosing groups (A 0%, B 15%, C 6%, p = 0.14), although major bleeding episodes were less common in group A (p < 0.05). There were no major procedural or in-hospital complications. Angiographic follow-up in 69% of the patients with successful angioplasty revealed target vessel patency in 91% but an angiographic restenosis rate of 59%. CONCLUSIONS: A prolonged supraselective intracoronary infusion of urokinase can be safely administered and may facilitate angioplasty of chronic total occlusions. Lower doses of urokinase are equally effective and result in fewer bleeding complications than do higher dosage regimens. Vessel patency is frequently maintained, but restenosis remains a problem.     

Attachment relationships in infant twins: the effect of co-twin presence during separation from mother

In this study the roles of the mother and the co-twin in inhibiting emotional arousal and reducing manifest distress of a twin who had been isolated in a modified strange situation were compared. The subjects were 15 children, each a member of a twin pair. The subjects were placed in a playroom under three conditions in the following order: (a) mother and twins present; (b) twins together, mother absent; (c) subject isolated from both co-twin and mother. The episodes in which all partners were together were alternated with brief separations. The subjects' distress was minimal when they were separated from the mother with the co-twin present. Upon reunion, stable social behavior was quickly restored. However, separation from the mother and co-twin produced a high level of distress for the subjects. When reunited, the isolated twin initiated physical contact with the mother, soliciting and receiving comfort from her. Furthermore, the distress of the isolated twin was transmitted to the co-twin who had remained with the mother during the isolation period. The nonisolated twin also solicited comfort from the mother. The presence of the co-twin during the reunion following isolation had little effect in reducing the subject twin's distress.