Search PubMed⌕ Search

Biomedical subjects

R De Vos

Publications and source records attributed to R De Vos.

87 records · Page 5Linked to original sources
PubMed1979

Electron microscopy of hepatitis B virus components in chronic active liver disease.

Eighteen liver biopsy specimens from patients with hepatitis B surface antigen (HBsAg) positive chronic aggressive hepatitis were studied by electron microscopy. All cases were selected on the basis of positive liver cell membrane fluorescence for HBsAg on immunohistochemical investigation. Striking changes in the morphology of the liver cell membrane were observed in nearly all cases. Furthermore, a dual aspect of hepatitis B core antigen (HBcAg) is described. HBcAg particles may occur as either 'naked' or 'cloudy' particles surrounded by semi electron dense material. The nature of the 'cloud' remains to be identified.

Chronic Disease↗
PubMed1978

Morphologic changes of the junctional complex of the hepatocytes in rat liver after bile duct ligation.

Using freeze-fracture techniques, we have examined the changes in the morphology of the tight junctional network around the canalicular lumen of the hepatocytes in rat liver after experimental bile-duct ligation. The more or less regular belt of parallel strands formed by the tight junctions around the canalicular lumen of normal hepatocytes is changed after extrahepatic obstruction. A more irregular network is formed withe a reduced number of strands which also extend more in an abluminal direction with formation of irregular loops. Striking changes are seen at the gap junctions: the small patches normally situated within the tight junctional network become less numerous; at some canaliculi they are even absent; also the larger gap junctional areas normally present in deeer abluminal extensions of the lateral cell membrane become hard to find or are even absent. This altered tight junctional pattern suggests an increased permeability so that the pathway of intercellular escape of biliary constituents towards the blood stream in cholestasis becomes as plausible as transhepatocytic regurgitation. The disappearance of the gap junctions would result in a lack of intercellular communication and uncoupling of liver cells, which may lead to a more individual behaviour of adjecent hepatocytes, explaining the heterogeneity in canalicular changes in cholestasis.

Animals↗
PubMed1977

Perinatal development of bilirubin UDP-glycosyltransferase activities in rat liver.

Bilirubin UDP-glucuronyltransferase and UDP-xylosyltransferase activity could already be demonstrated in rat liver from day 19 of fetal life onwards (4 days before birth). Bilirubin-glucuronide was present in hepatocytes of 21-day-old fetal liver strongly suggesting that the enzyme detected in vitro was really active in vivo. This further supports the theory that secretion from the cell is also immature. The known deficiency of UDP-glucose dehydrogenase in fetal and neonatal rat liver could lead to decreased intracellular concentrations of UDP-glucuronic acid and possibly to increased concentrations of UDP-glucose. However, no glucosides were present in the fetal hepatocytes.

Animals↗
PubMed1975

Progressive intrahepatic cholestasis (Byler's disease): case report.

This paper reports the case of a child in which the clinical and laboratory data indicate a progressive intrahepatic cholestasis of the type described as Byler's disease. The histological and histochemical findings suggest an intrahepatic cholestasis. Electron microscopy reveals interruptions of the bile canalicular membrane, which have been described as characteristic of this disease. A striking feature in the present case is the remarkable increase of microfilamentous structures in the pericanalicular ectoplasm and in the hepatocytic cytoplasm. The findings suggest a primary disturbance in bile acid secretion as the casue of cholestasis, entailing a hypertrophy of pericanalicular microfilaments which supposedly play a role in the final step of biliary secretion.

Bile Acids and Salts↗
PubMedDate not supplied

Are nuclear particles specific for non-A, non-B hepatitis?

This study reports the findings of an electron microscopic search for so-called non-A, non-B nuclear particles in liver biopsies from patients with mainly chronic or prolonged liver disease and from chimpanzees. In patients without hepatitis B virus or acute hepatitis A virus serological markers, non-A, non-B-like nuclear particles were seen in hepatocytes in 28 of 31 cases of presumed non-A, non-B hepatitis, but also in 11 of 12 cases of liver disease not usually attributed to hepatitis viruses. They were also seen in 22 of 24 patients with HBsAg, in 3 of 3 patients with anti-HBc and no HBsAg, in 1 of 2 patients with hepatitis A, in a case of cytomegalovirus hepatitis, and in 16 of 19 patients whose serology was not available or inconclusive. The particles were present in 1 of 8 untreated HBsAg-negative chimpanzees and in 2 of 2 HBsAg-positive chimpanzees. They appeared in 4 of 4 chimpanzees developing non-A, non-B hepatitis following exposure to various inocula. Three patterns of particle aggregates were distinguished, all of which had been shown by others in non-A, non-B hepatitis. Dense aggregates were predominant, while others have shown intermediate aggregates more often; reasons for this difference could be technical. No pattern was specific for any condition. Either non-A, non-B-like nuclear particles, although associated with non-A, non-B hepatitis, are not specific for this condition, or non-A, non-B hepatitis viruses are extremely more common than is currently appreciated.

Animals↗
PubMedDate not supplied

Ultrastructural immunocytochemical demonstration of HLA class I antigens in human pathological liver tissue.

Major histocompatibility complex products Class I (HLA Class I) antigens are not expressed on the surface of normal human hepatocytes but become so in pathological conditions. The purpose of this study was to specify the ultrastructural topography of HLA Class I antigens expression. Nine human liver specimens, known from light microscopic investigation to display membranous positivity for HLA Class I antigens, were processed for immunoelectronmicroscopy using monoclonal anti-HLA Class I in an indirect immunoperoxidase procedure. HLA Class I antigens were detected on the basolateral membrane of hepatocytes and bile duct cells; some cisternae of the endoplasmic reticulum were also positive. The membranes of normal bile canaliculi of hepatocytes and the apical border of bile duct cells were negative. In one case of presumably drug-induced cholestasis, abnormal cholestatic canaliculi displayed HLA Class I antigens. These results indicate that HLA Class I antigens are synthesized by the hepatocytes and bile duct cells and incorporated into the plasma membrane; the basolateral expression follows the pattern as in other polarized cells. The expression in cholestatic canaliculi suggests a disturbed polarity of the hepatocyte.

Bile Ducts↗
PubMedDate not supplied

COMFORT scale: a reliable and valid method to measure the amount of stress of ventilated preterm infants.

OBJECTIVE: Assessment of clinimetric properties and diagnostic quality of a stress measurement scale (COMFORT scale). DESIGN: Sample of an open population. SETTING: Neonatology department (Neonatal Intensive Care Unit), Academic Medical Centre/Emma Children's Hospital, Amsterdam, The Netherlands. METHOD: One clinical expert and 9 observers observed ventilated premature born babies simultaneously. Criterion validity was assessed by correlating the COMFORT scale with the clinical judgment regarding the amount of stress. Interobserver reliability was assessed on the clinical judgment as well as on the COMFORT scale. Diagnostic qualities were evaluated with a ROC curve. RESULTS: On 19 ventilated prematurely born babies (mean gestational age 30 weeks, mean birth weight 1385 gm), one clinical expert and 9 observers made 30 paired observations. The criterion validity of the COMFORT scale was good (Pearson's r of 0.84). The interobserver reliability of the clinical judgment was very good (weighted Kappa 0.84). The interobserver reliability of each item varied from good to almost perfect (weighted Kappa of 0.64 for muscle tone to 1.00 on heart rate). The reliability of the total COMFORT scale score was satisfying (intra-class correlation coefficient of 0.94). The diagnostic quality of the COMFORT scale was excellent, at a cut-off point of 20 the sensitivity was 100 percent, the specificity was 77 percent, and the area under the curve (AUC) of 0.95. CONCLUSION: In this first evaluation, the COMFORT scale appears to be a valid and reliable measurement tool to assess the stress of ventilated prematurely born babies.

Female↗
PubMedDate not supplied

Plasmacytoid monocytes in epithelioid cell granulomas: ultrastructural and immunoelectron microscopic study.

Plasmacytoid monocytes, the so-called plasmacytoid T cells, were originally described in rare cases of lymphadenitis. Recent immunohistochemical studies have demonstrated their monocytic origin. Plasmacytoid monocytes have in common with epithelioid cells and multinucleated giant cells the expression of several antigens; they also occur in close topographic association with epithelioid and multinucleated giant cells in epithelioid cell granulomas. On the basis of these data it has been suggested that plasmacytoid monocytes may transform into epithelioid cells. The present ultrastructural and immunoelectron microscopic study of epithelioid cell granulomas provides further arguments in favor of this hypothesis. Moreover, the existence of a transitional cell type with characteristics of plasmacytoid monocytes and epithelioid cells is documented. Subplasmalemmal linear densities present on focal areas of the plasma membrane of the main cell components of granulomas are also discussed.

Antigens, Surface↗