Characterization of an associated 16-kDa tyrosine phosphoprotein required for Ly-49D signal transduction

Ly-49D is an activating receptor on NK cells that does not become tyrosine phosphorylated upon activation. This report demonstrates that immunoprecipitation of Ly-49D, following pervanadate treatment or specific Ab cross-linking, coprecipitates a 16-kDa tyrosine-phosphorylated protein (pp16). Immunoblotting experiments and data from TCR-zeta/Fc epsilonRIgamma double knockout mice confirm that pp16 is not TCR-zeta, TCR-eta, or Fc epsilonRIgamma. Association of pp16 with Ly-49D involves a transmembrane arginine since mutation to leucine (Ly-49D[R54L]) abolishes association with pp16 in transfected P815 cells. In addition, Ly-49D(R54L) transfectants fail to mediate Ca2+ mobilization following Ab cross-linking. Therefore, signaling through Ly49D on NK cells depends on association with a distinct tyrosine phosphoprotein (pp16) in a manner analogous to that of TCR and FcR. Expression of this novel signaling peptide in both the NK and myeloid lineages indicates that pp16 is likely involved in the signal transduction cascade of additional receptor families.     

The role of pneumolysin and autolysin in the pathology of pneumonia and septicemia in mice infected with a type 2 pneumococcus

Mice were infected intranasally with a serotype 2 pneumococcus, a pneumolysin-negative derivative (PLN-A), or an autolysin-negative derivative (AL-2). Numbers of wild type pneumococci were seen in the lung from approximately 12 h after infection and were first detected in the blood around this time. Immunofluorescent staining of lung sections showed that pneumolysin was produced in vivo. Pneumococcal infection resulted in alteration of the composition of the blood but not the bone marrow. Some of the hematologic changes did not occur after PLN-A. PLN-A had a slower growth rate in the lung and bacteremia was delayed. AL-2 was rapidly cleared from the lungs and was not detected in the blood. These events paralleled the pattern of histology in the lung, with the severity of inflammation reduced with PLN-A and no inflammation or hematologic changes with AL-2.     

Adjustment to residential placement in Alzheimer disease patients: does premorbid personality matter?

AIM: To evaluate the influence of premorbid personality on adaptation to placement in a long-term care facility. SUBJECTS: Twenty-eight persons with probable Alzheimer disease (AD) residing in an academically affiliated nursing home for 6-9 months. METHODS: Premorbid personality was described retrospectively by two informants for each resident using the revised NEO Personality Inventory (NEO-PI-R). Standardized tests and rating scales were used on admission to the facility to assess cognition, mood state, physical dependency and general health. Nurses rated each AD resident's social behaviour, participation in activities and quality of sleep. RESULTS: Poorer adjustment was associated with more severe dementia but better physical health. None of the NEO-PI-R domain scores predicted adjustment. CONCLUSIONS: Contrary to popular belief, premorbid personality is relatively inconsequential for an AD patient's adaptation to a long-term care facility.     

The contribution of classical (beta1/2-) and atypical beta-adrenoceptors to the stimulation of human white adipocyte lipolysis and right atrial appendage contraction by novel beta3-adrenoceptor agonists of differing selectivities

The role of beta3- and other putative atypical beta-adrenoceptors in human white adipocytes and right atrial appendage has been investigated using CGP 12177 and novel phenylethanolamine and aryloxypropanolamine beta3-adrenoceptor (beta3AR) agonists with varying intrinsic activities and selectivities for human cloned betaAR subtypes. The ability to demonstrate beta1/2AR antagonist-insensitive (beta3 or other atypical betaAR-mediated) responses to CGP 12177 was critically dependent on the albumin batch used to prepare and incubate the adipocytes. Four aryloxypropanolamine selective beta3AR agonists (SB-226552, SB-229432, SB-236923, SB-246982) consistently elicited beta1/2AR antagonist-insensitive lipolysis. However, a phenylethanolamine (SB-220646) that was a selective full beta3AR agonist elicited full lipolytic and inotropic responses that were sensitive to beta1/2AR antagonism, despite it having very low efficacies at cloned beta1- and beta2ARs. A component of the response to another phenylethanolamine selective beta3AR agonist (SB-215691) was insensitive to beta1/2AR antagonism in some experiments. Because no [corrected] novel aryloxypropanolamine had a beta1/2AR antagonist-insensitive inotropic effect, these results establish more firmly that beta3ARs mediate lipolysis in human white adipocytes, and suggest that putative 'beta4ARs' mediate inotropic responses to CGP 12177. The results also illustrate the difficulty of predicting from studies on cloned betaARs which betaARs will mediate responses to agonists in tissues that have a high number of beta1- and beta2ARs or a low number of beta3ARs.     

Nutritional issues and therapy in inflammatory bowel disease

The molecular motions of D-alpha-galacturonic acid monohydrate (GA) and its derivative methyl-alpha-D-galacturonic acid methyl ester monohydrate (MGAM) in the solid state have been studied using 1H NMR. Both protonated and deuterium exchanged samples have been used. Spin-lattice relaxation times in the laboratory and rotating frames as well as second moments have been measured over the temperature range 90-370 K. Analysis of results has shown that in GA spin-lattice relaxation is chiefly by hydroxyl groups and water of crystallization. In MGAM, methyl groups dominate spin-lattice relaxation in the laboratory frame at the low temperature. Hydroxyl groups and water of crystallization contribute to the spin-lattice relaxation in the laboratory frame in the high temperature region. In the rotating frame motion of hydroxyl groups and water of crystallization provide the main relaxation pathway. Changes in the static second moment with temperature can be reasonably well predicted using values of correlation time and motionally averaged second moments obtained by fitting the spin-lattice relaxation data. 13C CPMAS spectra for GA and MGAM are also described.     

Ethanol inhibits hepatocyte proliferation in insulin receptor substrate 1 transgenic mice

BACKGROUND & AIMS: Long-term ethanol consumption is known to impair the ability of the liver to regenerate, but the molecular mechanisms are poorly understood. Multiple growth factors promote hepatocyte proliferation, some of which involve the insulin receptor substrate 1 (IRS-1)-mediated signal transduction pathway. To explore effects of ethanol on the IRS-1 signal liver growth in vivo, studies in transgenic mice overexpressing IRS-1 in the liver were performed because these mice show constitutive activation of the downstream signal transduction pathways leading to enhanced hepatocyte proliferation. METHODS: Tyrosyl phosphorylation of IRS-1 and subsequent protein-protein interactions were examined in liver lysates from animals fed ethanol or control diet. Activity of phosphatidylinositol-3 kinase (PI3K) and mitogen-activated protein kinase (MAPK) was assessed by specific enzymatic assays. Hepatocyte proliferation was measured by incorporation of [3H]thymidine into liver DNA. RESULTS: Tyrosyl phosphorylation of IRS-1, association of IRS-1 with PI3K, and activation of downstream PI3K and MAPK pathways were greatly reduced as a result of long-term ethanol consumption. Ethanol virtually abolished the enhanced hepatocyte DNA synthesis induced by expression of the IRS-1 transgene. CONCLUSIONS: Altered transmission of growth signals through the IRS-1-mediated signal transduction cascade may represent a molecular mechanism of how ethanol inhibits hepatocyte proliferation.     

Investigation on the strength–size relationship in fibrous structures including composites

The size effects due to changes in gauge length and the influence of the fragmentation phenomenon in fibrous structures are examined. First, a theoretical analysis of the differences of the size effects in single fibre and in a fibrous structure is conducted. Then comprehensive experimental work is presented on single fibres, fibre bundles, and twisted yarns which can be considered as pseudo-composites. Next a comparison is made between the theoretical predictions and the experimental data. Causes for the size effect in a fibrous structure are explored. © 1998 Chapman & Hall