Biomedical subjects

G Feldmann

Publications and source records attributed to G Feldmann.

At least 181 records · Page 10Linked to original sources

PubMed1988

Albumin and alpha-fetoprotein gene expression in various nonhepatic rat tissues.

Albumin and alpha-fetoprotein (AFP), two major serum proteins, are synthesized predominantly in the liver and yolk sac of mammals. In the present paper we report on the developmental expression of the corresponding genes in nonhepatic rat tissues. Significant quantities of mature albumin and AFP mRNAs were revealed in kidney, pancreas, heart, and lung of fetal and/or newborn rats using dot blot and Northern blot assays. Very low levels of these mRNA sequences were also detected in adult kidney and pancreas using sensitive RNA-cDNA solution hybridization assays. In situ hybridization analysis revealed that the albumin and AFP gene transcripts are present in the tubular cells of the 20-day-old fetal kidney. In order to elucidate further the mechanisms governing this expression, we studied the chromatin structure and methylation pattern in the 5'-end of these two genes. A faint band, corresponding to a specific DNase I-hypersensitive site upstream from the albumin gene, was detected in the fetal and neonatal kidney nuclei but not in adult kidney. For both genes, a site CG, demethylation of which is correlated with expression in liver and hepatoma cell lines, is highly methylated in fetal kidney even though AFP and albumin genes are expressed. Taken together, these results show the presence of a cell population in the rat kidney that actively transcribes both the albumin and AFP genes. The expression of these genes may be mediated by mechanisms differing in at least some steps from those exerted in the liver.

Animals↗

PubMed1988

Ultrastructural study of the semicircular canal cells of the frog Rana esculenta.

The ultrastructure of the nonsensory cells (dark cells, transitional cells, and undifferentiated cells) of the frog semicircular canal was studied by using transmission electron microscopy in an attempt to correlate the structure with the functions of these epithelial cells. All the nonsensory cells were linked by tight junctions and desmosomes; this suggested that there is little paracellular ionic transport from perilymph to endolymph. In the dark cell epithelium, the apical intercellular spaces were dilated; in the basal part, numerous basolateral plasma membrane infoldings, containing mitochondria, delimited electron-lucent spaces. The undifferentiated cells and the transitional cells were devoid of any basal membrane infolding. Surrounding the semicircular canal, very flattened and interdigitated mesothelial cells constituted a thin multilayer tissue which limited the perilymphatic space. The morphological aspect of the dark cells suggests that they may play a role in the secretion and/or in the reabsorption of endolymph, which bathes the apical pole of these cells. The undifferentiated and transitional cells can play a role in the maintenance of the endolymphatic ionic composition because of their apical tight junctions and desmosomes.

Animals↗

PubMed1988

Liver phospholipidosis induced by parenteral nutrition: histologic, histochemical, and ultrastructural investigations.

Histochemical and electron microscopic examinations of the liver were performed in 5 adults receiving parenteral nutrition for greater than 18 mo and in 4 adults receiving parenteral nutrition for less than 5 mo. Phospholipidosis, reflected by the presence of cytoplasmic phospholipid deposits at histochemical examination and the presence of multilamellar lysosomes at electron microscopy, was marked and present in hepatocytes, Kupffer cells, and portal macrophages in all 5 patients receiving parenteral nutrition for greater than 18 mo. Mild phospholipidosis, affecting only hepatocytes, was demonstrated in 3 of the 4 patients receiving parenteral nutrition for less than 5 mo. These findings indicate that liver phospholipidosis is relatively common in patients receiving parenteral nutrition and that the degree of liver phospholipidosis depends on the duration of parenteral nutrition. Liver phospholipidosis might be due to intrahepatic accumulation of intravenous phospholipids provided by fat-emulsion sources.

Adult↗

PubMed1988

Peliosis hepatis, nodular regenerative hyperplasia of the liver, and light-chain deposition in a patient with Waldenström's macroglobulinemia.

We report the case of a female patient suffering from Waldenström's macroglobulinemia with three different liver lesions: peliosis hepatis, nodular regenerative hyperplasia, and light-chain deposits within the sinusoidal walls. We hypothesize that both peliosis hepatis and nodular regenerative hyperplasia might be the consequence of a disordered intrahepatic circulation determined by light-chain deposits infiltrating the sinusoidal walls.

Biopsy↗

PubMed1988

Amitriptyline-induced prolonged cholestasis.

We report the case of a patient in whom amitriptyline administration for 5 wk was followed by prolonged cholestasis. Jaundice and pruritus lasted 19 and 20 mo, respectively. Three liver biopsies were performed at different stages of the disease showing the course of liver lesions. Cholestasis initially located in the region of the hepatic venule came to be associated with the progressive development of portal tract lesions consisting of inflammatory infiltration, fibrosis, and disappearance of interlobular bile ducts. Amitriptyline hydroxylation and dextromethorphan O-demethylation are deficient in subjects with the poor metabolizer phenotype of debrisoquine. Drug oxidation phenotyping with dextromethorphan showed that this patient had the extensive metabolizer phenotype. This observation demonstrates that amitriptyline can induce prolonged cholestasis and suggests that the susceptibility to develop liver injury while taking this drug may not be related to a genetic deficiency of its hydroxylation.

Adult↗

PubMed1988

Epithelioid hemangioendothelioma of the liver. Diagnostic features and role of liver transplantation.

Five cases of epithelioid hemangioendothelioma of the liver are reported. This unusual type of vascular tumor is often difficult to diagnose; its angiogenic nature is not overt at the radiologic level and may be overlooked by conventional histologic examination. At imaging procedures, epithelioid hemangioendothelioma of the liver presents as multiple focal hypovascular areas, disseminated in both lobes. The combination of these imaging abnormalities with a peculiar set of demographic and clinical features, including young age, good general condition, and progressive course, is suggestive. However, the final diagnosis can be established only by histologic examination of appropriate material collected by guided liver biopsies and may be helped by immunohistochemistry and ultrastructural examination. The accurate diagnosis of epithelioid hemangioendothelioma of the liver is of clinical and therapeutic relevance. In view of its favorable clinical course, orthotopic liver transplantation may be considered for the treatment of this tumor when intrahepatic dissemination contraindicates partial hepatectomy and extrahepatic extension, excluded by exploratory laparotomy, is absent.

Adult↗

PubMed1988

Alpha fetoprotein and albumin gene transcripts are detected in distinct cell populations of the brain and kidney of the developing rat.

We report the cellular localization of alpha-fetoprotein (AFP) and albumin (ALB) gene transcripts in rat kidney and brain as detected by in situ hybridization on tissue sections with [35S]-labelled alpha-fetoprotein and albumin cDNA probes. Both types of mRNA were present in distinct cell populations of the developing kidney and brain. In the kidney, both gene transcripts were distributed over all developing tubular cells in the 20-day-old fetus. During the first 3 weeks of life, a gradual decrease in the expression of AFP and ALB mRNA was apparent, the rate of decrease being greater on proximal tubules than on the other tubular cells. From the 4th week onwards, a weak signal for both mRNAs persisted in the majority of the tubular cells. In the brain, all neuronal cells expressed both genes. Transcript cellular distribution was mainly cytoplasmic during fetal and early postnatal life and became predominantly nuclear at 3, 4 and 5 weeks, suggesting that posttranscriptional mechanisms are involved in the control of AFP and ALB gene expression at these stages. In the adult brain no significant signal was recorded thereafter. Coexpression of AFP and ALB transcripts by specific cell types, together with their gradual disappearance concomitant with postnatal organ maturation, suggests a possible role for these proteins in terminal differentiation processes of tubular and neuronal cells.

Aging↗

PubMed1988

Immunoperoxidase localization of bile salts in rat liver cells. Evidence for a role of the Golgi apparatus in bile salt transport.

The mechanisms of intracellular transport of bile acids from the sinusoidal pole to the canalicular pole of the hepatocyte are poorly understood. There is physiological and autoradiographic evidence for a vesicular pathway. The purpose of this study was to determine the localization of natural bile acids in the liver using antibodies against cholic acid conjugates and ursodeoxycholic acid. An indirect immunoperoxidase technique was used on rat liver sections fixed either with paraformaldehyde (PF) and saponin, a membrane-permeabilizing agent that allows penetration of antibodies into the cell, or with PF alone. Retention of taurocholate in the liver after tissue processing was 26 +/- SD 15% of the bile acid initially present. When sections fixed with PF and saponin were incubated with the antibody against cholic acid conjugates, a granular cytoplasmic staining was observed by light microscopy in all hepatocytes. By electron microscopy, strong electron-dense deposits were observed mostly on vesicles of the Golgi apparatus (GA) and, sometimes, in the smooth endoplasmic reticulum (SER). After taurocholate infusion, the intensity of the reaction increased. When the liver was fixed with PF alone, almost no reaction was visible on light microscopy, but on electron microscopy the label was localized on the hepatocyte plasma membrane, mainly on the bile canalicular domain and to a lesser extent on the sinusoidal domain. With the antibody against ursodeoxycholic acid, no staining was observed in three of four livers, and a slight staining was observed in one. However, after infusion of ursodeoxycholic acid, staining of GA and SER vesicles was observed when the liver was fixed with PF and saponin. With PF alone, the reaction was intense on the canalicular membrane. These results support the view that, within the limits of the method, vesicles from the GA and possibly vesicles of the SER are involved in the intracellular transport of bile acids before canalicular secretion.

Animals↗

PubMed1988

Analysis of hepatocyte plasma membrane domains during rat development using monoclonal antibodies.

The plasma membrane of adult rat hepatocyte consists of three domains, which have been identified by the monoclonal antibodies A39 and A59 as markers of the sinusoidal domain, B1 of the lateral, and B10 of the canalicular domains (Eur J Cell Biol 39:122, 1985). These monoclonal antibodies were used to study, by indirect immunocytochemistry, formation of the hepatocyte plasma membrane domains during development, from day 15 of gestation to day 35 post partum. The antigens defined by A39, B1, and B10 were detected, from day 15, over the major part of the hepatocyte plasma membrane except for the membranes of newly formed bile canaliculi, which were not labeled by B1 and only poorly labeled, if at all, by A39 and B10. As soon as fetuses were 16 days old, B1 labeled predominantly the lateral domain, as in the adult. Labeling with B10 progressively intensified on the membranes of bile canaliculi, but localization was not exclusively canalicular until day 21 post partum. A39 intensely labeled the canalicular membranes at 19-21 days of gestation, while at 35 days post partum it exhibited the predominantly sinusoidal labeling observed in adult hepatocytes. The antigen defined by A59 was not detected before birth and was found exclusively on the sinusoidal domain, as in the adult. These results show that the patterns of antigen distribution on different plasma membrane domains establish themselves at different rates. The marked differences observed between fetal or neonatal and adult hepatocytes might be responsible for immaturity of liver functions in the neonate.

Animals↗

PubMed1988

Formation of plasma membrane domains in rat hepatocytes and hepatoma cell lines in culture.

In vivo, proteins of the hepatocyte plasma membrane are asymmetrically distributed, making it possible to distinguish a sinusoidal, a lateral and a canalicular domain. The conditions that determine hepatocyte plasma membrane polarity have been investigated in vitro, using three monoclonal antibodies directed against integral membrane proteins, which were characteristic of each domain. The localization of the three antigens was studied by immunolabelling of hepatocytes isolated from adult rat liver, primary monolayer cultures and rat hepatoma cell lines. When hepatocytes were isolated, the three antigens spread over the entire cell surface. The lateral antigen redistributed at lateral sites as soon as cell-cell contacts were established, 4 h after the beginning of primary culture. The sinusoidal and canalicular antigens became asymmetrically distributed after 48 h of primary culture, after the formation of bile canaliculus-like structures. In most of the hepatoma lines studied, the three antigens were expressed, except that the canalicular antigen was fully expressed in differentiated clones only. The lateral antigen was always distributed on the contiguous membranes of clustered hepatoma cells, whereas the sinusoidal and canalicular antigens were localized on the entire plasma membrane. However, in a few cells of some clones in which bile canaliculus-like structures were observed, the canalicular membranes were strongly labelled only with the canalicular antibody. In the absence of bile canalicular formations, in both primary culture and cell lines, the canalicular antigen and, to a lesser extent, the sinusoidal antigen accumulated in the Golgi apparatus, suggesting that their transport to the cell surface was altered in the absence of a bile pole. These results show that in hepatic cells, polarization of the plasma membrane is determined by: (1) the existence of cell-cell contacts, which is correlated with the domain-specific localization of the lateral antigen; and (2) the formation of bile canaliculi, which would trigger the development of an asymmetrical distribution of the sinusoidal and canalicular antigens.

Animals↗

PubMed1988

Osseointegrated oral implants. A Swedish multicenter study of 8139 consecutively inserted Nobelpharma implants.

Fourteen Swedish teams outside the University of Gothenburg, each with minimally three years' experience in the Nobelpharma osseointegrated implant participated in a retrospective multiclinic study. The total number of consecutively inserted implants at the 14 clinics was 8139. The outcome of every implant was reported and all implant failures, irrespective of when they occurred, were published. The success criteria included absence of implant mobility, absence of radiolucent zones on x-rays, and an annual bone loss after the first year of less than 0.2 mm. In the mandible 334 implants were followed for five to eight years, with only three failures, for a success rate of 99.1%. In the maxilla 106 implants were followed for five to seven years, with a success rate of 84.9%. In irradiated and grafted mandibles, 56 implants were inserted and none was lost during a follow-up of up to five years. In the irradiated maxilla there were 16 implants inserted with three reported failures and in the grafted upper jaw 71 implants were inserted with 12 failures. The proportions of mandibular and maxillary sleeping implants were 0.8 and 0.3%, of patient drop-out implants 0.3 and 0.6%, and of patient death implants 0.9 and 1.2%, respectively. It was concluded that the osseointegrated implant, if inserted according to the guidelines of Brånemark, results in a very high degree of clinical success, thereby meeting any published oral implant success criteria.

Clinical Trials as Topic↗

PubMed1988

Cellular analysis of alpha-fetoprotein gene activation during carbon tetrachloride and D-galactosamine-induced acute liver injury in rats.

To analyze the cellular mechanisms of alpha-fetoprotein (AFP) gene activation during liver regeneration, we have measured the steady-state level of liver AFP mRNA by dot blot and revealed AFP transcripts and protein in liver sections by in situ hybridization and immunoperoxidase. AFP gene activation was studied from rats intoxicated with carbon tetrachloride or D-galactosamine, two toxics inducing different patterns of liver necrosis and regeneration. At 48 and 72 hours of carbon tetrachloride intoxication, liver AFP mRNA steady-state levels were slightly increased. On liver sections, large necrotic centrilobular areas were apparent with a 7- to 10-fold increase of hepatocyte mitotic index as compared with controls. At the same times of intoxication, a 2-fold increase in the signal level for AFP mRNA over all nonnecrotic hepatocytes was observed, whereas the protein remained undetectable in most of the hepatocytes. In contrast, after D-galactosamine intoxication, no increase of AFP mRNA steady-state levels was detectable. Scattered necrotic hepatocytes were visible at 48 and 72 hours of intoxication, with only a 2-fold increase of hepatocyte mitotic index, as compared with controls. Moreover, while the hybridization signal level for AFP mRNA was not increased over hepatocytes, large amounts of AFP mRNA and protein were detected in proliferated oval cells and bile duct-like structures. These results suggest that at least two distinct mechanisms at the cellular level may explain AFP gene activation during chemically-induced liver regeneration: (a) a moderate increase of AFP mRNA by all the remaining hepatocytes probably linked to their reentry into the proliferative cycle, which appears the main mechanism after carbon tetrachloride intoxication, and (b) a quantitatively important AFP expression by a small number of proliferated cells with new phenotypes (oval cells and bile-duct like structures), observed in the D-galactosamine model.

Animals↗

PubMed1988

Peliosis hepatis and sinusoidal dilation during infection by the human immunodeficiency virus (HIV). An ultrastructural study.

The description of hepatic sinusoidal lesions in a significant number of acquired immunodeficiency syndrome (AIDS) patients prompted the authors to undertake an ultrastructural study of the sinusoidal barrier abnormalities during human immunodeficiency virus (HIV) infection, in order to compare these lesions with those described in other conditions and to discuss their possible origin. In a series of 29 patients with serologic evidence of HIV infection and liver abnormalities, 8 (28%) had sinusoidal lesions. Peliosis hepatis was present in 2 cases, and sinusoidal dilatation in 6. These patients were classified as follows: 3 AIDS, 4 AIDS-related complex, 1 unclassifiable. Ultrastructural lesions of the sinusoidal barrier were observed in all the cases. They closely mimicked the changes previously reported in peliotic and peliotic-like changes of various origins. A striking particularity was, however, the presence of numerous and hyperplastic sinusoidal macrophages. This work suggests that an injury of the endothelial cells, directly or indirectly related to the presence of HIV, may be incriminated in the pathogenesis of sinusoidal lesions during HIV infection.

AIDS-Related Complex↗

PubMed1988

Transferrin secretion and hepatocyte ploidy: analysis at the single cell level using a semi-automatic image analysis method.

In a previous work it was shown that transferrin (Tf) secretion is directly related to the membrane surface area of hepatocytes (Péchinot D. et al. [31]). The aim of the present work was to search for a possible relationship between Tf secretion and hepatocytic ploidy using a semi-automatic image analysis method. A determination of Tf secretion by isolated normal adult hepatocytes was achieved at the single cell level, using a modified reverse hemolytic plaque test. A Feulgen reaction was also performed on these hepatocytes. It allowed the evaluation, for each secreting hepatocyte, of the quantity of Tf secreted and its nuclear characteristics. Discrimination between diploid (2c) and tetraploid (4c and 2c2c) hepatocytes was performed and the amount of Tf secreted by each subpopulation determined. It appeared that a 2-fold secretion ratio was not found between tetraploid and diploid hepatocytes. These results suggest, as Tf production is not directly proportional to the degree of ploidy of hepatocytes, that some not yet elucidated regulatory mechanisms may act on Tf gene expression.

Animals↗

PubMed1987

Biosynthesis and regulation of rat alpha 1-inhibitor3, a negative acute-phase reactant of the macroglobulin family.

The biosynthesis of rat alpha 1-inhibitor3, a negative acute-phase reactant specifically found in rodents, was studied in vitro in a cell-free translation system from rabbit reticulocytes, in rat hepatocyte primary cultures and in vivo by immunocytochemistry using normal and turpentine-injected rats. By sucrose-gradient centrifugation and subsequent translation of the fractionated RNA in vitro it was found that the mRNA coding for alpha 1-inhibitor3 exhibited a size of about 28S. For the alpha 1-inhibitor3 translated in vitro an apparent Mr of 155,000 was determined. A continuous decrease in the level of alpha 1-inhibitor3 in serum during experimental inflammation induced by turpentine injection was demonstrated by means of quantitative 'rocket' immunoelectrophoresis. This result agrees with the observation by immunocytochemistry of a drastic decrease in alpha 1-inhibitor3 levels in hepatocytes 24 h after turpentine injection. At that time alpha 1-inhibitor3 is mainly located in the Golgi apparatus, whereas it is also present in the membranes of the rough and smooth endoplasmic reticulum when normal liver is used. All hepatocytes, but no other hepatic cells, contain alpha 1-inhibitor3. When hepatocyte primary cultures were labelled with [35S]methionine and alpha 1-inhibitor3 was immunoprecipitated from the hepatocyte medium and the supernatant of homogenized cells, two different forms of alpha 1-inhibitor3 were found. The intracellular form of alpha 1-inhibitor3, with an apparent Mr of 173,000, is characterized by oligosaccharide side chains of the high-mannose type. The form of alpha 1-inhibitor3 in the medium exhibited an Mr of 186,000 and carried carbohydrate side chains of the complex type. After labelling hepatocytes with radioactive sugars, [3H]mannose was found in both forms of alpha 1-inhibitor3, whereas [3H]fucose and [3H]galactose were incorporated only into the form found in the medium. In the presence of tunicamycin an unglycosylated alpha 1-inhibitor3 with an apparent Mr of 154,000 was found in cells and in the medium. In a pulse-chase experiment it was shown that inhibition of glycosylation by tunicamycin resulted in a marked delay of secretion of alpha 1-inhibitor3. Thus the oligosaccharide side chains of alpha 1-inhibitor3 play an important role during its transport into the medium.

Acute-Phase Proteins↗

PubMed1987

Comparison of the effects of a preliminary hepatic washing and of saponin on the intracellular penetration of peroxidase-labeled anti-rat albumin antibodies in hepatocytes.

The effect of a preliminary hepatic washing with saline before liver fixation either by perfusion or immersion was compared to the effect of saponin, a membrane-permeabilizing agent, in order to ascertain which procedure is best to obtain a homogeneous distribution of albumin-containing hepatocytes in the hepatic lobule. Albumin was located in the hepatocytes by peroxidase-labeled antibodies using light and electron microscopy. The efficacy of the two procedures on the intracellular penetration of labeled antibodies in liver sections was judged by preparing transverse ultrathin sections. Both procedures yielded similar results. Liver fixation by perfusion with saponin and without a preliminary washing, however, distributes albumin-containing hepatocytes more homogeneously in the hepatic lobule and enables labeled antibodies to penetrate more satisfactorily. In contrast, when the liver is fixed by immersion, the preliminary washing is the only way to obtain an even distribution of albumin-containing hepatocytes, as saponin is not effective under these conditions. In conclusion, the localization of albumin in the hepatocytes must be adapted according to the technique used to fix the liver.

Albumins↗

PubMed1987

The hepatic sinusoid in hairy cell leukemia: an ultrastructural study of 12 cases.

Ultrastructural lesions of the liver were studied in 12 cases of hairy cell leukemia, with the alterations of the sinusoidal barrier receiving special emphasis. Portal and sinusoidal tumoral infiltration was observed in all cases. It was associated with angiomatous lesions of the sinusoids in eight cases; these lesions consisted of randomly distributed cavities lined by hairy cells and containing hairy cells and erythrocytes. In addition to the attachment of hairy cells to the sinusoidal wall, other striking electron microscopic abnormalities of the sinusoids included 1) wide areas of communication between the sinusoidal lumen and Disse's space, allowing extravasation of blood cells; 2) focal disruption of the sinusoidal wall; and 3) replacement of the sinusoidal cell lining by tumor cells in close contact with hepatocytes. Most of these changes closely resembled those observed in peliosis hepatis. As in peliosis, sinusoidal alterations in hairy cell leukemia might be due to the destruction of the sinusoidal wall, and tumor cells could play a role in the pathogenesis of the lesions. The pattern of liver involvement in hairy cell leukemia, which is peculiar among hepatic localizations of blood malignancies, might reflect the unique phenotype of the tumor cells.

Humans↗

PubMed1987

Detection of albumin mRNAs in rat liver by in situ hybridization: usefulness of paraffin embedding and comparison of various fixation procedures.

Our aim was to define optimal conditions for efficient and reproducible albumin mRNA detection in rat liver by in situ hybridization. We used an albumin-specific [3H]-labeled cDNA probe with a specific activity of 6-8.10(6) cpm/microgram DNA. In situ hybridization is as efficient on paraffin sections as on cryostat sections for detecting albumin mRNAs. Perfusion fixation with a 4% paraformaldehyde solution results in homogeneous RNA retention within tissue blocks, in contrast with immersion fixation, which yields heterogeneous RNA preservation. Comparison of immersion fixation with three different fixatives (paraformaldehyde, ethanol-acetic acid, and Bouin's fixative) shows that the highest level of hybridization signal is obtained with paraformaldehyde. Ethanol-acetic acid and Bouin's fixative appear less efficient for albumin mRNA detection. Loss of mRNAs within liver tissue blocks over time is largely although not completely prevented by paraffin embedding.

Albumins↗