Pattern mixture models for multivariate normal data: a simulation study

Little&Wand (1996) introduced the pattern mixture model for wave nonresponse as a special case of multivariate normal longitudinal data with fixed covariate matrix. This paper was the theoretical foundation and the induce to investigate the pattern mixture model compared with complete case analysis by means of simulations. The main point of interest was the mean square error of the estimated model parameters and the efficiency of the estimations. To estimate the variance of the model parameters we examine the Jackknife method. Parameter estimates by the pattern mixture model are very satisfying under ignorable mechanism but they have to be scanned carefully under nonignorable mechanism. The Jackknife method seems to be, with restrictions, a good estimator for the variance of the model parameters

Longitudinal data with dropouts: a comparison of pattern mixture models with complete case analysis

Pattern mixture models constitute an alternative to selection models (Little & Rubin, 1987). Little & Wang (1996) introduced pattern mixture models for analyzing multivariate normal longitudinal data with missing values. This paper was the theoretical foundation and the induce to investigate the small sample properties of pattern mixture models compared with complete case analysis. The main point of interest, of the simulations, was the mean square error of the estimated model parameters. Parameters estimated by the pattern mixture model are very satisfying under ignorable mechanism but they have to be scanned carefully under nonignorable mechanism

Granularzelltumor des Larynx

Zusammenfassung: Granularzelltumoren (GZT) sind subkutan oder submukös gelegene, gutartige Tumoren neurogenen Ursprungs. Sie treten häufig im Kopf-Hals-Bereich auf, insbesondere in der Zunge. Bisher wurden etwa 200 laryngeale GZT beschrieben. Meist sind dabei die Stimmlippen und die posteriore Glottis betroffen. Eine Unterscheidung von einer chronischen Entzündung oder einem Malignom ist nur mittels Biopsie möglich. Als Therapie der Wahl wird die vollständige Exzision empfohlen, wobei Tumorausdehnung und zu erwartende Morbidität die Radikalität des Vorgehens bestimmen. Bei vollständiger Entfernung sind Rezidive selte

HACD1, a regulator of membrane composition and fluidity, promotes myoblast fusion and skeletal muscle growth

The reduced diameter of skeletal myofibres is a hallmark of several congenital myopathies, yet the underlying cellular and molecular mechanisms remain elusive. In this study, we investigate the role of HACD1/PTPLA, which is involved in the elongation of the very long chain fatty acids, in muscle fibre formation. In humans and dogs, HACD1 deficiency leads to a congenital myopathy with fibre size disproportion associated with a generalized muscle weakness. Through analysis of HACD1-deficient Labradors, Hacd1-knockout mice, and Hacd1-deficient myoblasts, we provide evidence that HACD1 promotes myoblast fusion during muscle development and regeneration. We further demonstrate that in normal differentiating myoblasts, expression of the catalytically active HACD1 isoform, which is encoded by a muscle-enriched splice variant, yields decreased lysophosphatidylcholine content, a potent inhibitor of myoblast fusion, and increased concentrations of ≥C18 and monounsaturated fatty acids of phospholipids. These lipid modifications correlate with a reduction in plasma membrane rigidity. In conclusion, we propose that fusion impairment constitutes a novel, non-exclusive pathological mechanism operating in congenital myopathies and reveal that HACD1 is a key regulator of a lipid-dependent muscle fibre growth mechanism

Structural and optical quality of GaN grown on Sc2O3/Y2O3/Si(111)

Thick (∼900 nm) GaN layers were grown by molecular beam epitaxy on cost-effective Sc2O3/Y2O3/Si(111) substrates and characterized by x-ray diffraction and photoluminescence. Samples grown in Ga-rich condition show superior structural and optical quality with reduced density of cubic GaN inclusions within the hexagonal matrix and a relatively strong photoluminescence emission at 3.45 eV at 10 K. Cubic inclusions are formed in the initial growth stage and their concentration is reduced with increasing film thickness and after rapid thermal annealing

Synthesis and characterization of precursors for group II metal aluminates

Precursors to Group II metal aluminates (MAI 2 O 4 , M=Mg, Ca, Ba, Sr) are synthesized from inexpensive starting materials including Group II metal oxides/hydroxides, Al(OH) 3 , triethanolamine (TEA) and ethylene glycol, in a one-pot synthesis process. The precursors are soluble in common organic solvents and can be handled in moist air for a reasonable period of time. On pyrolysis in air to 1200 °C, all three precursors transform to the corresponding Group II metal aluminates. A termetallic double alkoxide, ‘ionomer-like’ structure is proposed, wherein the alkaline-earth metal is encapsulated by a TEA molecule bridging two alumatrane units. The precursors were characterized using TGA, NMR, mass spectroscopy and elemental analyses, and the pyrolysed precursors were briefly characterized using x-ray diffraction analysis. © 1997 John Wiley & Sons, Ltd.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/38300/1/666_ftp.pd

“Feeling Warmth and Close to Her”: Communication and Resilience Reflected in Turning Points in Positive Adult Stepchild–Stepparent Relationships

With the goal of understanding the development of positive stepchild–stepparent relationships, the researchers focused on turning points characterizing the interaction of adult stepchildren who have a positive bond with a stepparent. Engaging a relational turning points perspective, 38 stepchildren (males and females, ages 25 to 52 years old) who reported a positive stepparent relationship were interviewed, generating 269 turning points which were categorized into 15 turning point types and coded by valence. Turning points occurring most frequently were: prosocial actions, quality time, conflict/ disagreement, changes in household/family composition, and rituals. Findings are discussed, including implications for developing and enacting resilient and positive stepchild–stepparent relationships and future directions for researchers wanting to focus on positive family interaction

“Feeling Warmth and Close to Her”: Communication and Resilience Reflected in Turning Points in Positive Adult Stepchild–Stepparent Relationships

With the goal of understanding the development of positive stepchild–stepparent relationships, the researchers focused on turning points characterizing the interaction of adult stepchildren who have a positive bond with a stepparent. Engaging a relational turning points perspective, 38 stepchildren (males and females, ages 25 to 52 years old) who reported a positive stepparent relationship were interviewed, generating 269 turning points which were categorized into 15 turning point types and coded by valence. Turning points occurring most frequently were: prosocial actions, quality time, conflict/ disagreement, changes in household/family composition, and rituals. Findings are discussed, including implications for developing and enacting resilient and positive stepchild–stepparent relationships and future directions for researchers wanting to focus on positive family interaction

Absence of the neutrophil serine protease cathepsin G decreases neutrophil granulocyte infiltration but does not change the severity of acute pancreatitis

Acute pancreatitis is characterized by an early intracellular protease activation and invasion of leukocytes into the pancreas. Cathepsins constitute a large group of lysosomal enzymes, that have been shown to modulate trypsinogen activation and neutrophil infiltration. Cathepsin G (CTSG) is a neutrophil serine protease of the chymotrypsin C family known to degrade extracellular matrix components and to have regulatory functions in inflammatory disorders. The aim of this study was to investigate the role of CTSG in pancreatitis. Isolated acinar cells were exposed to recombinant CTSG and supramaximal cholezystokinin stimulation. In CTSG(-/-) mice and corresponding controls acute experimental pancreatitis was induced by serial caerulein injections. Severity was assessed by histology, serum enzyme levels and zymogen activation. Neutrophil infiltration was quantified by chloro-acetate ersterase staining and myeloperoxidase measurement. CTSG was expessed in inflammatory cells but not in pancreatic acinar cells. CTSG had no effect on intra-acinar-cell trypsinogen activation. In CTSG(-/-) mice a transient decrease of neutrophil infiltration into the pancreas and lungs was found during acute pancreatitis while the disease severity remained largely unchanged. CTSG is involved in pancreatic neutrophil infiltration during pancreatitis, albeit to a lesser degree than the related neutrophil (PMN) elastase. Its absence therefore leaves pancreatitis severity essentially unaffected