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A Geerts

Publications and source records attributed to A Geerts.

83 records · Page 5Linked to original sources
PubMedDate not supplied

Purified rat liver fat-storing cells in culture divide and contain collagen.

Primary cultures and cell lines were established from suspensions of purified fat-storing cells isolated from the rat liver. When seeded at a suitable density, fat-storing cells in primary culture reached confluency in 3 to 4 days and could be transferred and established as cell lines for at least two passages. The typical morphological characteristics of fat-storing cells in vivo were retained in the cells during primary culture. Vitamin A fluorescence was still associated with lipid droplets of cells in culture up to and including the second passage. Investigation of the cytoskeletal structure by indirect immunofluorescence showed the presence of vimentin, actin and tubulin in the cells; no alpha-prekeratin was present. The presence of vimentin suggested a fibroblastic or possible myogenic origin for fat-storing cells. The presence of connective tissue components in fat-storing cells in culture was demonstrated by indirect immunofluorescence. Collagen Types I and IV and laminin were present intracellularly in small granules in fat-storing cells in primary culture and in the first passage. Cells in the fourth passage contained only collagen Type 1. Fibronectin was only aligned extracellularly along the cell membrane, which did not exclude an extracellular source. Rat liver fat-storing cells in culture show a high proliferating capacity. Cell multiplication during prolonged culture was associated with phenotypic transition to a more fibroblastic appearance and gradual disappearance of vitamin A. These results indicate that fat-storing cells may be among the cell types involved in pathological changes observed during development of liver fibrosis.

Actins↗
PubMedDate not supplied

Antioxidant enzyme gene expression in rats with remnant kidney induced chronic renal failure.

Reactive oxygen intermediates play a role in chronic renal injury and glomerulosclerosis. We investigate changes in renal cortex antioxidant enzyme gene expression in the rat remnant-kidney model of chronic renal failure and compare the new data to enzyme activities published earlier. Antioxidant enzyme gene expression is evaluated by Northern blot analysis of cortex mRNA, using cDNA probes for catalase, copper/zinc-containing superoxide dismutase, and glutathione peroxidase. Catalase gene expression decreases during development of renal failure; this decrease is accompanied by decreased catalase activity during the glomerulosclerosis phase of the remnant-kidney model. Copper/zinc superoxide dismutase and glutathione peroxidase gene expression remain at a normal level during progression of the model, whereas their activities show a temporary decrease in the early remnant kidney. In the remnant-kidney model, catalase seems to be more vulnerable to reactive oxygen intermediates than superoxide dismutase and glutathione peroxidase. Our results show that antioxidant enzyme activity and gene expression do not change in the same direction at all times during disease development and that all antioxidant enzymes do not respond in the same way.

Actins↗
PubMedDate not supplied

Pyruvate-induced long-term maintenance of glutathione s-transferase in rat hepatocyte cultures.

The addition of pyruvate to the culture medium has been reported to improve the maintenance of P450-dependent enzyme expression in primary rat hepatocyte cultures. In this study, the effects of 30mM pyruvate on cell morphology, albumin secretion and glutathione S-transferase (GST) expression were investigated as a function of the time in culture. The effect of triiodothyronine (T3) exposure on GST expression was also measured in pyruvate-treated cultures. Transmission electron microscopy showed that untreated hepatocytes deteriorated after culture for 7 days, whereas the morphology of the pyruvate-treated cells was similar to that observed in intact liver tissue. The albumin secretion rate was significantly higher in rat hepatocytes exposed to pyruvate than in control cells. In the presence of pyruvate, mu and alpha class GST activities were well maintained, whereas GST pi activity was increased over the entire culture period. HPLC analysis revealed that the complement of GST subunits present in hepatocytes is altered during culture with pyruvate: mu,class proteins remained relatively constant, whereas a decrease in the alpha class content was accompanied by a strong increase in GST subunit P1 (GSTP1). The induction of GSTP1 was confirmed at the mRNA level. In control cultures, pi class GST activity was increased, but total, mu, and alpha class GST activities continuously declined as a function of culture time and became undetectable beyond 7 days in culture. At the protein and mRNA levels, a much smaller increase in GSTP1 was observed than in the pyruvate cultures. When the pyruvate-treated cell cultures were exposed to T3, an inhibitory effect on GST activities and proteins was found. These results indicate that this simple culture model could be useful for studying the expression and regulation of GST.

Albumins↗
PubMedDate not supplied

Insufficient TGF-beta 1 production inactivates the autocrine growth suppressive circuit in human ovarian cancer cell lines.

TGF-beta 1 is a secreted polypeptide that elicits an antiproliferanve response in many cell types. However, many epithelial cancer cell lines are resistant to TGF-beta 1 growth inhibition. We investigated the in vitro growth suppressive effect of TGF-beta 1 on five ovarian cancer cell lines. Two of these (OVCAR-3 and AZ364) were growth inhibited by TGF-beta 1. The other three cell lines (SKOV-3, AZ224 and AZ547), were resistant to the antiproliferative action of the cytokine. All five cell lines produce TGF-beta 1 mRNA at very different levels and also secrete the TGF-beta 1 polypeptide, but mainly in a biologically latent form as tested by ELISA; this probably explains the fact that the TGF-beta 1 autocrine growth inhibition circuit is not active, even in sensitive cell lines. Even complete activation of the in vitro secreted latent form would be insufficient to induce growth arrest when compared to the levels of exogenous TGF-beta 1 needed to induce growth arrest in sensitive cell lines. The TGF-beta 1 receptor type I mRNA is expressed by all five ovarian cancer cell lines, but two of them (AZ224 and AZ547) lack detectable TGF-beta 1 receptor type II mRNA expression. Since TGF-beta 1 signaling requires both receptor types, the lack of receptor type II in two cell lines may explain their resistance to growth inhibition. Further experiments should be carried out on receptors and downstream components to pinpoint the cause of resistance in the SKOV cell line.

Activin Receptors, Type I↗
PubMedDate not supplied

Trichostatin A, lead compound for development of antifibrogenic drugs.

Eukaryotic gene expression has mainly been studied in the context of trans-acting transcription factors and their interaction with regulatory cis-elements. Evidence is accumulating, that the higher order structure of chromatin also plays an essential role in eukaryotic gene expression. Hepatic stellate cells are the major cellular source of extracellular matrix synthesis in chronic liver diseases leading to fibrosis. We explored the antifibrogenic effect of the histone deacetylase inhibitor trichostatin A (TSA) on hepatic stellate cells in vitro. Primary hepatic stellate cells as well as activated, subcultured stellate cells were exposed to 10(-7) M-10(-9) M TSA. Collagens type I and III, and smooth muscle alpha-actin (alpha-SMA), a marker for transdifferentiation, were investigated at the protein and mRNA level by performing Northern hybridisation and quantitative immunoprecipitation. The antiproliferative effect was examined by 3H-thymidine incorporation and cell counting. Hyperacetylation of histone H4 was demonstrated by acid urea Triton-X-100 (AUT) polyacrylamide gel electrophoresis. TSA at 10(-7) M retarded the morphological changes characteristics for activation of primary stellate cells. Synthesis of collagens type I and III, and alpha-SMA was strongly inhibited at both protein and mRNA level. The proliferation rate of primary hepatic stellate cells was strongly suppressed by 10(-7) M TSA. Hyperacetylation of histone H4 showed to be maximal at 10(-7) M TSA. Primary hepatic stellate cells were more affected by TSA than subcultured stellate cells.

Animals↗
PubMedDate not supplied

Metastatic follicular dendritic cell sarcoma of the stomach: a case report and review of the literature.

Follicular dendritic cell (FDC) sarcomas are rare tumours, typically seen in lymph nodes. However, in about one third of the reported cases, a FDC sarcoma presents as an extranodal mass. Involvement of the gastrointestinal tract is extremely rare, and only 3 cases have been described to date. We report on a 40-year-old female patient with a follicular dendritic cell sarcoma located in the stomach and the presence of a metastasis in the liver at the time of diagnosis. Severe asthenia, nausea, back pain and loss of weight were the presenting symptoms. A CT scan of the abdomen and an upper gastrointestinal endoscopy revealed a tumour mass in the stomach. The diagnosis of a FDC sarcoma was made on histological and immunohistochemical findings. We report the second case of a FDC sarcoma presenting in the stomach. Due to its rarity, a FDC sarcoma seldom enters the differential diagnosis of spindle cells neoplasms of the gastrointestinal tract. Complete surgical resection is the treatment of choice for FDC sarcoma.

Adult↗
PubMedDate not supplied

Contributions of light and transmission electron microscopy to the study of the human fat-storing cell.

We examined the human fat-storing cell (Ito cell, lipocyte) in normal and pathologic liver biopsies using toluidine blue staining and transmission electron microscopy. We studied 5 normal patients, 6 non-alcoholic patients with liver steatosis, 8 patients with early alcoholic liver damage, 4 patients with extrahepatic cholestasis, 10 patients with chronic active hepatitis B (N = 2) or C (N = 8) with mild fibrosis, 5 patients with alcoholic cirrhosis and 4 with posthepatitic cirrhosis. We found that fat-storing cells were increased in patients with alcoholic steatofibrosis and extrahepatic cholestasis and decreased in cirrhotic patients. The mean number of lipid droplets per fat-storing cell was significantly increased in patients with alcoholic steatofibrosis. Transmission electron microscopy confirmed the light microscopic findings, especially the accumulation of lipid droplets in fat storing cells in early alcoholic liver disease. Sometimes lipid droplets with different electron density were noted. In cirrhosis there was a more prominent development of intracellular organelles, and cells often changed into a more elongated, myofibroblast-like shape.

Adipose Tissue↗