PADGEM (GMP140) is a component of Weibel-Palade bodies of human endothelial cells

PADGEM protein (PADGEM), also known as GMP140, is a platelet alpha- granule membrane protein that is translocated to the external membrane after platelet activation. Although the biosynthesis of this protein was originally thought to be confined to megakaryocytes, the synthesis of PADGEM in endothelial cells was recently demonstrated (McEver et al: Blood 70:1974a, 1987). We now describe the subcellular localization of this protein in endothelial cells. Immunofluorescence staining of permeabilized human umbilical vein endothelial cells with KC4, a well characterized monoclonal antibody to PADGEM, showed positively stained elongated structures similar in distribution and shape to Weibel-Palade bodies. Their identity as Weibel-Palade bodies was confirmed by double label immunofluorescence using KC4 and a polyclonal antiserum to von Willebrand factor (vWf), a protein known to be specifically stored in these organelles. All Weibel-Palade bodies were found to contain PADGEM. In contrast to strong perinuclear staining produced with anti- vWf antibodies, no significant perinuclear staining was obtained with KC4, indicating that relatively little PADGEM is present in the endoplasmic reticulum and in the Golgi apparatus. In endothelial cells treated with secretagogues that stimulate vWf release the elongated structures positive for PADGEM disappeared, further identifying these structures as Weibel-Palade bodies. This observation extends the parallels between Weibel-Palade bodies and alpha-granules and suggests a possible functional association between vWf and PADGEM.     

Slowly progressive aphasia without generalized dementia: studies with positron emission tomography

Slowly progressive aphasia without generalized dementia is a degenerative syndrome selectively affecting dominant hemisphere language areas. We report changes in regional glucose metabolism measured by positron emission tomography in two patients with this condition. Striking abnormalities of glucose utilization in the left cerebral cortex were demonstrated in both patients. The findings of other neurodiagnostic studies were relatively unremarkable. The first patient had a 3-year history of progressive anomia and impaired auditory verbal recall. An electroencephalogram was normal, and computed tomography showed mild left perisylvian atrophy. Positron emission tomography revealed profound hypometabolism in the left temporal regions. The second patient also had a 3-year history of progressive anomia. Electroencephalography, computed tomography, and magnetic resonance imaging scans were normal. Positron emission tomography showed a major reduction in left parietal glucose utilization, with a lesser decrement in left temporal metabolism. Neither patient demonstrated significant contralateral or global abnormalities such as those reported in positron emission tomographic studies of Alzheimer's disease with or without focal clinical features. These observations support the concept of adult-onset progressive aphasia without dementia as a clinical syndrome distinct from Alzheimer's disease.     

Gated myocardial perfusion single photon emission computed tomography in the clinical outcomes utilizing revascularization and aggressive drug evaluation (COURAGE) trial, Veterans Administration Cooperative study no. 424

Background  Stress gated myocardial perfusion single photon emission computed tomography (gSPECT) is increasingly used before and after intercurrent therapeutic intervention and is the basis for ongoing evaluation in the Department of Veterans Affairs clinical outcomes utilizing revascularization and aggressive drug evaluation (COURAGE) trial. Methods and Results  The COURAGE trial is a North American multicenter randomized clinical trial that enrolled 2287 patients to aggressive medical therapy vs percutaneous coronary intervention plus aggressive medical therapy. Three COURAGE nuclear substudies have been designed. The goals of substudy 0 are to examine the diagnostic accuracy of the extent and severity of inducible ischemia at baseline in COURAGE patients compared with patient symptoms and quantitative coronary angiography and to explore the relationship between inducible ischemia and the benefit from revascularization when added to medical therapy. Substudy 1 will correlate the extent and severity of provocative ischemia with the frequency, quality, and instability of recurrent symptoms in postcatheterization patients. Substudy 2 (n _ 300) will examine the usefulness of sequential gSPECT monitoring 6 to 18 months after therapeutic intervention. Together, these nuclear substudies will evaluate the role of gSPECT to determine the effectiveness of aggressive risk-factor modifications, lifestyle interventions, and anti-ischemic medical therapies with or without revascularization in reducing patients’ ischemic burdens. Conclusions  The unfolding of evidence on the application of gSPECT in trials such as COURAGE defines a new era for nuclear cardiology. We hope the evidence that emerges from the COURAGE trial will further establish the role of nuclear imaging in the evidence-based management of patients with stable coronary disease. The COURAGE trial was supported by the Cooperative Studies Program of the Department of Veterans Affairs Office of Research and Development in collaboration with the Canadian Institutes of Health Research. Unrestricted research grants were obtained from Merck & Co; Pfizer Pharmaceuticals; Bristol-Myers Squibb Medical Imaging; Astellas Pharma; Kos Pharmaceuticals; Data Scope; Astra Zeneca Pharmaceuticals; Astra-Zeneca-Canada; Schering-Plough Coorporation, Ltd; Sanofi-Aventis, Inc; First Horizon; and GE Healthcare. All industrial funding for this trial was directed through the Department of Veterans Affairs. Additional funding for this substudy was provided by grants to the Department of Veterans Affairs and Canadian Institutes of Health Research from Astellas Pharma and Bristol-Myers-Squibb Medical Imaging.     

BUILDING THE FOUNDATION OF EXCELLENCE IN HEART FAILURE NURSING

This column contains the presidential address presented during the Third Annual Meeting of the American Association of Heart Failure Nurses on June 28, 2007, in San Diego, California, titled "Building the Foundation of Excellence in Heart Failure Nursing."     

Predicting occupational performance: handwriting versus keyboarding.

PURPOSE: To determine whether there is a correlation between handwriting and keyboarding speed and accuracy, and whether handwriting and keyboarding share common underlying components. METHODS: Sixty-three typically developing 5th-grade students attended a series of 15 keyboarding lessons for a total of 5 hours. Prior to the lessons, cognitive, sensory, and motor skills related to handwriting were evaluated. Prior to and following the lessons keyboarding and handwriting accuracy and speed were also tested. Correlations were employed to examine relationships between handwriting and keyboarding skills and multiple regression analyses were used to examine the contribution of performance components to handwriting and keyboarding performance. RESULTS: Following keyboarding instruction, a significant correlation was found between handwriting and keyboarding speed, but not in accuracy of these tasks. Similarly, some of the specific tests measuring tactile and oculo-motor functions were found to be related to both handwriting and keyboarding speed, yet accuracy of these tasks did not share common underlying components. CONCLUSIONS: It appears that handwriting and keyboarding accuracy may entail different skills, suggesting that keyboarding may be a potential alternative writing tool for students with handwriting difficulties. It also appears that when students write slowly, handwriting speed should be considered prior to recommending keyboarding for these students. Additional research is required to further support these findings.     

Mutations of the human thyrotropin-beta subunit glycosylation site reduce thyrotropin synthesis independent of changes in glycosylation status.

In recent studies, site-directed mutagenesis has been used to alter the tripeptide glycosylation recognition sequences of glycoprotein hormone subunits, thereby affecting their structure and function. However, it is not known whether these effects result from changes in glycosylation status, amino acid sequence, or both. We therefore studied the synthesis of wild-type and mutant recombinant human thyrotropins produced by transient transfection of a human cell line. Mutating the TSH-beta subunit glycosylation recognition sequence, Asn-Thr-Thr (codons 23-25), to either Gln-Thr-Thr or Asn-Thr-Tyr abolished subunit glycosylation, as demonstrated by the inability to incorporate 3H-carbohydrates. However, a third mutation (Asn-Thr-Ser) contained an intact glycosylation recognition sequence site, and was shown to retain glycosylation. The mutations that abolished TSH-beta subunit glycosylation resulted in greater than 90% decreases in TSH synthesis. However, the glycosylation recognition sequence mutant that retained beta subunit glycosylation exhibited a 70% decrease in TSH production. These decreases were not attributable to the intracellular accumulation of TSH or its free beta subunit. We also engineered two TSH-beta subunit mutations that did not alter the glycosylation recognition sequence. A glycine to arginine mutation adjacent to the glycosylation recognition sequence, in a region thought to be critical for heterodimer formation, abolished TSH production. In contrast, shortening the TSH-beta subunit carboxyterminus by six amino acids increased TSH synthesis.(ABSTRACT TRUNCATED AT 250 WORDS)