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.     

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."     

Congenital herpes simplex retinitis

An 1,810-g girl born at 37 weeks of gestation had true congenital herpes simplex virus type 2 infection. The neonate was born with hypo-pigmented skin lesions, brain lesions, and old heavily pigmented retinal scars in the posterior pole. There was no active ocular disease. Viral cultures, immunoperoxidase stains, and antibody determination by enzyme-linked immunosorbent assay were all positive for herpes simplex virus. Treatment with acyclovir healed the lesions within ten days. The clinical and laboratory findings indicated that the herpetic infection probably occurred in the second trimester.     

Paediatric lung transplantation.

Since 1990, lung transplantation has been performed in infants, children and adolescents in small numbers, and the numbers, in comparison with adult transplants, remain small today. The indications for lung transplantation are similar in childhood when compared with adults, but the disease entities are distinct. In children, severe pulmonary vascular disease is most commonly associated with developmental abnormalities or congenital heart disease, as opposed to idiopathic pulmonary hypertension. Cystic fibrosis is the dominant indication for lung transplantation in older childhood and adolescence. The operative approach to lung transplantation in early life differs from that in adults, in that cardiopulmonary bypass is more likely to be utilised and bilateral lung transplantation is strongly preferred to single lung transplantation. Living donor lung transplantation is proportionately more common in children and adolescents than in adults. Post-transplant complications related to viral infection and post-transplant lymphoproliferative disease are more common and more likely to be severe and life-threatening. Bronchiolitis obliterans is the most important complication after paediatric lung transplantation and limits both the quality of life and duration of survival, as in adults.     

Localization of amyloid precursor protein in GAP43-immunoreactive aberrant sprouting neurites in Alzheimer's disease.

Previous in vitro studies have suggested that amyloid precursor protein (APP) could be involved in cell surface adhesion, neuritic growth and survival of hippocampal neurons. In the present study, involvement of APP in aberrant sprouting in Alzheimer's disease (AD) was studied by comparing immunolabeling patterns of anti-APP and anti-growth-associated protein 43 (anti-GAP43). Confocal laser imaging of frontal cortex sections double-immunolabeled for APP and GAP43 showed an increase, in AD, of presynaptic boutons immunostained with anti-GAP43 that contained anti-APP immunoreactivity. The neuritic plaques in AD cases presented intense anti-GAP43 immunoreactive abnormal neurites colocalized with anti-APP. Three-dimensional reconstruction of the plaques showed that anti-APP was colocalized with anti-GAP43 in 57.5% of the aberrant sprouting neurites. We conclude that co-expression of APP with GAP43 in the plaque might be involved in the aberrant sprouting response observed in AD.     

Three-dimensional analysis of the relationship between synaptic pathology and neuropil threads in Alzheimer disease.

Recent studies have shown that the Alzheimer disease (AD) neocortex is characterized by a loss of large neurons, the presence of dilated terminal axons, widespread loss of synapses, and a disruption of the dendritic cytoskeleton which is manifested as Tau immunoreactive threads. In the present study we have investigated the relationship between synaptic and dendritic abnormalities in the neocortex of Alzheimer patients and examined the extent to which these structural alterations correlate with the severity of cognitive impairment in AD. Quantitative neuroanatomical data were obtained from immunofluorescence-labeled specimens using a laser-scanning confocal microscope, computer-assisted image processing and serial section reconstruction techniques. We found that the AD cases showed a 34% loss in the number of presynaptic terminals per 100 square (sq) microns, many of which showed structural abnormalities. The AD neuropil had an average of 10 +/- 7 dendritic threads per 1,000 sq microns, with the average thread measuring 2 sq microns. Severe AD cases had thicker threads compared with mild to moderate AD cases. Three-dimensional analysis showed clustering of synapses around threads, as well as presynaptic boutons apposed to dendritic neuropil threads. Statistical analysis showed that the strongest correlation was between synapse density and Blessed score of cognitive impairment. Thread counts did not correlate with either but were correlated with tangle counts. Stepwise multiple regression analysis showed that tangle counts, but not threads, strengthened the correlation between Blessed score and synapses. We conclude that synaptic damage may precede dendritic thread and tangle formation, and that threads do not necessarily induce synaptic pathology. Instead, dendrite sprouting in the denervated regions could be associated with increased accumulation of cytoskeletal proteins observed in the dendritic threads.     

Multiple cutaneous granular cell tumors in childhood

We have described two children with multiple cutaneous granular cell tumors (GCT) and have reviewed the literature. Multiple tumors of the skin are relatively rare, especially in children, with only 18 pediatric cases previously reported. Surgical excision of rapidly growing or symptomatic lesions is the treatment of choice. In these two children with multiple GCT, three lesions were excised. Specific stains for enolase and S-100 protein clearly demarcated tumor margins after surgical excision. Despite intensive investigation, the histogenesis of this tumor is still in dispute. The most tenable theory at this time is that these tumors are derived either directly from Schwann cells or from undifferentiated cells developing neural characteristics.