Unequal distribution of membrane components between pseudopodia and cell bodies of platelets.

Platelet pseudopodia were compared to platelet cell bodies with respect to their lipid composition, fatty acid distribution and protein composition. The methodology for producing pseudopodial preparations of platelets stimulated with thrombin, ADP or calcium ionophore was established. The separation of pseudopodia and cell bodies was verified by electron microscopic examination of the respective platelet components. Lipid analyses demonstrated a preponderance of lysophospholipids and sphingomyelin in pseudopodial preparations and a large increase in mono-, di- and tri-ene fatty acids as compared to cell bodies. Changes were also evident in the protein composition evaluated by one- and two-dimensional SDS-polyacrylamide gel electrophoresis and by [32P]ATP labeling of exofacial membrane proteins. A protein of approximately 68 kDa which reacted strongly with antibody to PlA1, was prominantly displayed in platelet pseudopodia. Thus, our studies demonstrate a heterogeneous distribution of lipids and proteins in a mammalian membrane system which may have important implications for the functional behavior of the cell.

Permeabilization of platelets: an investigation of biochemical, ultrastructural and functional aspects.

The biochemical, ultrastructural and functional aspects of digitonin-permeabilized platelets were investigated. Human platelets were permeabilized by exposure to the steroid glycoside digitonin. A 60 microM concentration of this permeabilizer produced a very substantial release of cytosolic enzymes from the platelets. Release from subcellular granules was relatively low and did not inhibit the response of platelets to a series of agonists. Although digitonin-permeabilized platelets required higher threshold concentrations of the usual stimulants, both primary and secondary aggregation as well as the release of nucleotides and enzymes from their respective granules remained intact. Transmission electron micrographs revealed discontinuities in the plasma membrane of digitonin-treated platelets, but scanning electron microscopy showed no difference between control and permeabilized platelets. No substantial loss of structural or membrane proteins could be detected by one- and two-dimensional gel electrophoresis. The pore size produced by digitonin treatment was sufficient to allow entry of 125I-labeled IgG into the platelet cytosolic space.

Cerebral amyloid angiopathy manifesting as recurrent intracerebral hemorrhage.

Over a period of eight years, a normotensive woman experienced eight strokelike episodes. Computed tomographic (CT) scans obtained during each of the last seven episodes demonstrated intracerebral lobar hemorrhage. Cerebral angiography and contrast-enhanced CT scans demonstrated no underlying abnormality. Our patient had recurrent intracerebral hemorrhage (ICH) with no predisposing factors or dementia. The clinical diagnosis was primary cerebral amyloid angiopathy (CAA). Brain biopsy specimens demonstrated light microscopic and ultrastructural evidence of amyloid in cerebral arterioles. We believe that the combined clinical, CT, and ultrastructural changes in this case are unique. Recurrent ICH visualized by CT scanning has diagnostic value in CAA.

Lectin binding to parietal cells of human gastric mucosa.

A light microscopic and ultrastructural analysis of lectin receptors on parietal cells from human gastric mucosa was performed utilizing 12 biotinylated lectins in conjunction with an avidin-biotin-peroxidase complex. Peanut agglutinin conjugated directly to peroxidase was also used. Several fixatives and fixation regimens were evaluated for optimal preservation of parietal cell saccharide moieties. Formalin proved to be the most practical fixative for light microscopic studies. A periodate-lysine-paraformaldehyde (PLP) combination provided good preservation of lectin binding capacity but yielded relatively poor ultrastructure. Conversely, glutaraldehyde provided excellent preservation of ultrastructure but a somewhat diminished lectin binding activity, which was overcome by using long incubation times and high concentrations of reagents. Parietal cells reacted strongly with Bandieraea simplicifolia, Dolichos biflorus, peanut agglutinin, and soybean agglutinin (all specific for galactosyl/galactosaminyl groups) and weakly with Ulex europaeus (specific for fucose). At the light microscopic level a beaded, perinuclear staining pattern was observed which, ultrastructurally, corresponded to an intense staining of intracytoplasmic canaliculi. The membranes of the intracytoplasmic canaliculi were characterized by an abundance of galactosyl residues, a paucity of fucosyl groups, and a lack of mannosyl and glucosyl residues. The biochemical and physiological significance of these findings is discussed.

Gastric adenocarcinoma: prognostic significance of several pathologic parameters and histologic classifications.

Considerable controversy exists about the value of histologic classifications of gastric adenocarcinoma in the prediction of patient survival. Histologic sections of 75 consecutive gastrectomies were used to compare Lauren and Ming classifications with emphasis on clinical stage, size, location of tumor, desmoplasia, inflammatory reaction, and 5-year survival. Both classifications generally correlated and, when combined, proved helpful in defining certain cases. At surgery, about one third of the total cases of intestinal (INT, Lauren) and expanding (ET, Ming) were in early stages, whereas almost all the diffuse (DT, Lauren) and infiltrative (INF, Ming) types were in late stages. When the Lauren classification was applied to preoperative endoscopic biopsies, a 72% diagnostic correlation with the surgical specimens was found. Followup revealed no survivors of the DT and INF and 12 and 11 survivors of INT and ET, respectively, regardless of stage. Inflammatory response was associated with good prognosis. Desmoplasia and size had no prognostic significance. Tumors of the cardia had worse prognoses than those in the body or antrum. Both Lauren and Ming classifications, and especially the degree of inflammation, were significant in predicting survival. Lauren INT and Ming ET should be declared only when they are the sole or predominant features.

Lymphocytic bronchiolitis associated with HIV infection.

Patients with the acquired immune deficiency syndrome (AIDS) frequently develop interstitial lung disease. This is due most commonly to opportunistic infections, but malignancy and lymphocytic interstitial pneumonitis have also been associated with the syndrome. In contrast, there has been little reported about airways disease in patients with HIV infection. We describe a patient with AIDS-related complex who presented with symptoms and radiographic evidence of micronodular interstitial lung disease. Transbronchial biopsy revealed a lymphocytic bronchiolitis but no evidence of interstitial lung disease and a marked T-suppressor lymphocytosis was found on analysis of the bronchoalveolar lavage (BAL) specimen. Routine fungal, viral and bacterial cultures did not yield an etiologic agent. This case raises the possibility that lymphocytic bronchiolitis may represent another pulmonary manifestation of HIV infection.

Primary hepatic carcinoid tumor. An electron microscopic and immunohistochemical study.

A case of primary carcinoid tumor of the liver with striking morphologic and electron microscopic features is reported. Conventional histologic examination showed a prominent paranuclear clear zone in numerous tumor cells. By electron microscopic examination, this clear zone corresponded to a paranuclear mass of intermediate filaments admixed with neurosecretory granules and other cytoplasmic organelles.

False-positive reactions in the latex agglutination test for Cryptococcus neoformans antigen.

The latex agglutination test for Cryptococcus neoformans antigen is a simple and rapid procedure for the diagnosis of cryptococcal meningitis. Although the test is sensitive, care must be taken to prevent contamination of the sample, which may result in false-positive reactions. It was discovered in our laboratory that immersion of a platinum wire inoculating loop into a sample of cerebrospinal fluid prior to testing introduced interfering substances leading to nonspecific agglutination. After further studies, it was determined that trace amounts of surface condensation (syneresis fluid) from agar, either added to the cerebrospinal fluid or adhering to the loop, were the probable source of contamination. It is suggested that the latex agglutination test for C. neoformans antigen be performed prior to culture or on a separate sample.

Restrictive pulmonary disease due to interlobular septal fibrosis associated with disseminated infection by Strongyloides stercoralis.

Strongyloidiasis is caused by the nematode Strongyloides stercoralis. The parasite has a unique life cycle that enables it to cause a hyperinfection syndrome in which pulmonary involvement is characteristic. We describe the case of a 68-yr-old Hispanic male from Puerto Rico with disseminated strongyloidiasis who developed intense granulomatous reaction in the lung associated with interlobular septal fibrosis. Granulomatous lung disease leading to fibrosis within the lung has been well demonstrated in schistosomiasis, another parasitic disease. This case represents the first report, as far as we are aware, of fibrosis within the lung and restrictive pulmonary disease in association with Strongyloides stercoralis.

Erythropoietin has a mitogenic and positive chemotactic effect on endothelial cells.

Erythropoietin is known to be a hematopoietic growth factor with a singularly specific action on the proliferation and differentiation of erythroid progenitor cells. We have observed a dose-dependent proliferative action of human recombinant erythropoietin on human umbilical vein endothelial cells and bovine adrenal capillary endothelial cells. Binding studies with radioiodinated recombinant human erythropoietin revealed a large number (approximately 27,000) of an apparent single class of receptors with an affinity in the 10(-9) M range. Linkage of the radiolabeled ligand to its receptor via a bifunctional crosslinking agent allowed us to identify an endothelial cell protein of 45 kDa as the principal receptor associated with this mitogenic effect of erythropoietin. Recombinant human erythropoietin also enhanced the migration of endothelial cells.

Mucin histochemistry of intestinal metaplasia in Barrett's esophagus.

Histological and histochemical evaluation of 33 biopsies and 8 distal esophagectomy specimens revealed specialized columnar epithelium with intestinal features [intestinal metaplasia (IM)] to be the most common type (91%) of metaplasia in Barrett's esophagus (BE). Junctional epithelium was found in only 3 of the 33 biopsies. The type III subvariety of IM (TIII-M), characterized by the presence of sulfomucins in the non-goblet columnar cells, was found in 58% of all our biopsies and 62% of operative specimens. Six of the 7 cases of epithelial dysplasia were associated with TIII-M; one of them subsequently developed an adenocarcinoma. The transitional epithelium adjacent to adenocarcinomas in the operative specimens also showed TIII-M in five of six cases. Our findings indicate that TIII-M is almost as common in Barrett's-associated carcinoma as in nonneoplastic cases of BE, thereby limiting the usefulness of this histological marker as an indicator of neoplastic change (P = 0.5). On the other hand, TIII-M seems to be significantly associated with mild dysplasia in BE. The value of TIII-M as a prognostic indicator regarding the subsequent development of esophageal carcinoma remains in doubt and could be more precisely assessed by a prospective study.

Bronchoalveolar lavage in talc induced lung disease.

A 65 year old woman with a history of occupational talc inhalation presented with hypoxaemia, cough, and dyspnoea with a normal chest radiograph. Bronchoalveolar lavage showed considerable lymphocytosis, with a predominance of T8+ T lymphocytes, and open lung biopsy showed peribronchiolar granulomas containing talc crystals. Corticosteroid treatment resulted in dramatic improvement. Bronchoalveolar lavage may aid in the diagnosis of talc related lung injury.

Comparative sensitivities and specificities of the mass measurements of CK-MB2, CK-MB, and myoglobin for diagnosing acute myocardial infarction.

We evaluated the clinical utility of the mass measurement of the tissue isoform of creatine kinase MB isoenzyme (CK-MB2) in the diagnosis of an acute myocardial infarction (AMI) by determining its sensitivity, specificity, and predictive value relative to those of CK-MB mass and myoglobin. Samples were obtained at 0, 4, 8, and 16 h postpresentation from 100 patients (41% with AMI). The order of sensitivity for the sample proportions taken at 0-2 h from the onset of symptoms was myoglobin > CK-MB2 > CK-MB. At all other time points, the sensitivity of CK-MB2 either equaled or surpassed that of both CK-MB and myoglobin, although the 95% confidence intervals for the population proportions each of these markers overlapped. Of the 41 AMI patients, 31 (76%) exhibited concurrent abnormal increases of CK-MB and %CK-MB2; the other 10 (24%; 8 non-Q wave, 2 Q wave) exhibited abnormal values for %CK-MB2 before their CK-MB exceeded the upper limit of normal. The specificity of myoglobin was statistically lower than that for either CK-MB2 or CK-MB at all time points.

Erythropoietin receptor mRNA expression in human endothelial cells.

A previous report demonstrated that endothelial cells have erythropoietin receptors and respond to this hormone with enhanced proliferation. The present study demonstrates the existence of mRNA for erythropoietin receptor in human umbilical vein endothelial cells. We have reverse transcribed mRNA of endothelial cells and then used different PCR primers to amplify erythropoietin receptor target cDNA between exons 5 and 6 as well as 3-5 in addition to an internal standard DNA fragment. Correspondence of size as well as location of restriction endonuclease scission (Ava II) was used in comparing the amplified fragments of human endothelial cell erythropoietin receptor to those of two human erythroleukemia cell lines, OCIM1 and K562. No alpha- or gamma-globin mRNA was detected in endothelial cells but was readily demonstrable in OCIM1 cells. In addition, to determine whether the expression of human erythropoietin receptor on endothelial cells occurs in vivo, sections of umbilical cord and placenta were immunostained with antibodies against the extracellular portion of the receptor; the results showed strong positive staining of the vascular endothelium.