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Biomedical subjects

S Linder

Publications and source records attributed to S Linder.

At least 109 records · Page 6Linked to original sources
PubMed1993

Nonenzymatic extraction of cells from clinical tumor material for analysis of gene expression by two-dimensional polyacrylamide gel electrophoresis.

We have compared different methods of preparation of malignant cells for two-dimensional electrophoresis (2-DE). We found all methods using fresh tissue to be superior compared to methods using frozen tissue. Our results indicate that nonenzymatic methods of preparation of tumor cells, including fine needle aspiration, scraping and squeezing, have advantages over methods using enzymatic extraction of cells. Nonenzymatic methods are rapid, appear to reduce loss of high molecular protein species, and alleviate the necessity of separating viable and nonviable cells by Percoll gradient centrifugation. Using these techniques, high-quality 2-DE maps were derived from tumors of the lung and breast. In the resulting polypeptide patterns, heat shock proteins, non-muscle tropomyosins and intermediate filament were identified. We conclude that nonenzymatic extraction of malignant cells from fresh tumor tissue improves the possibilities that these techniques may be useful in clinical diagnosis.

Animals↗
PubMed1993

Repression of stromelysin metalloprotease expression in rat fibrosarcoma cells by dimethylsulfoxide.

Metalloproteases are implicated in conferring invasive properties to tumor cells. We show here that treatment of ras-oncogene-transformed rat fibroblasts with dimethylsulfoxide (DMSO) results in a reversible decrease in stromelysin mRNA. Furthermore, stromelysin expression was found to be repressed by DMSO, but not by glucocorticoid hormone, in a fibrosarcoma cell line showing low AP-1 (fos/jun) transcription factor activity. In two fibrosarcoma cell lines which express high levels of stromelysin and low levels of 68 kDa type IV collagenase, the DMSO-induced decrease in stromelysin expression was paralleled by a decreased invasive propensity.

Animals↗
PubMed1993

Serum levels of CA 19-9 and CA 50 in relation to Lewis blood cell status in patients with malignant and benign pancreatic disease.

Serum expression of the cancer-associated antigens CA 19-9 and CA 50 and their relation to Lewis blood cell status were studied in 26 patients with pancreatic duct carcinoma and 26 patients with pancreatitis. The discriminating capacity between benign and malignant disease was high for both tumor markers. The correspondence between serum levels of CA 19-9 and CA 50 was close irrespective of the Lewis phenotype of the patient. All cancer patients with normal levels of CA 19-9 and CA 50 were of the phenotype Le(a-b-). Knowledge of the Lewis phenotype may therefore add vital information when tumor marker assays are used for diagnosis and monitoring of malignant pancreatic disease.

Adult↗
PubMed1993

Bile duct pressure, hormonal influence and recurrent bile duct stones.

An obstacle to the outflow from the bile duct not only increases bile duct pressure but also facilitates the formation of primary bile duct stones. The bile duct pressure, an indicator of the balance between bile inflow and outflow, was studied postoperatively under similar conditions in 123 patients, who had been operated on for bile duct stones. Secondary bile duct stones had been present in 86 patients (group CC) and primary stones in 26 (group C), while 11 without sphincter of Oddi function were used as a control group. The basal bile duct pressure was similar in groups CC and C, but significantly lower in the controls. Intraductal injection of saline solution caused a similar increase in bile duct pressure in groups CC and C, but not in the controls. Intravenous administration of secretin and somatostatin increased the bile duct pressure in groups CC and C, while a "normal" response to cholecystokinin, a decrease in bile duct pressure, was observed only in group CC. The "abnormal" response to cholecystokinin found in group C indicates a motor dysfunction of the sphincter of Oddi, which may have been responsible for, or at least contributed to, the formation of recurrent bile duct stones in this group.

Adult↗
PubMed1993

Lack of c-jun expression in a transformed cell line isolated by glucocorticoid promotion of ras-transfected rat embryo fibroblasts.

Rat embryo fibroblasts (REFs) are inefficiently transformed by the T24-ras oncogene. A contributing factor to cellular resistance to transformation is the limited tolerance to p21-ras oncoprotein expression. Here we present data suggesting that long-term glucocorticoid treatment of ras oncogene-transfected REFs results in increased tolerance to p21-ras oncoproteins, leading to expression of the transformed phenotype. Stably transformed cell lines that expressed high levels of H-ras and could be maintained in the absence of hormone were isolated. In three out of four lines studied, the AP-1-dependent collagenase gene was expressed at a low level. In one of these lines, low collagenase expression was paralleled by lack of c-jun mRNA. Immunochemical analysis revealed that progression to hormone independence was not paralleled by mutations in the p53 gene. We propose that a decreased expression of AP-1-driven genes may result in increased tolerance to p21-ras oncoprotein.

Animals↗
PubMed1992

Elevated stromelysin-1 and reduced collagenase-IV expression in invasive rat embryo fibroblasts expressing E1A deletion mutants + T24-H-ras.

We have studied the in vitro invasive properties of 3 cell lines derived from the co-transfection of rat embryo fibroblasts (REF) with EIA genes deficient in exon 2 and T24-ras. All 3 cell lines showed invasive properties at passage 10 after isolation. Invasive cells expressed elevated levels of stromelysin-1 and reduced levels of 68-kDa type-IV collagenase compared with untransfected REF. In 2 cell lines the invasive capacity increased during in vitro propagation. The expression of stromelysin-1 increased during this process, whereas 68-kDa type-IV collagenase was persistently expressed at reduced levels. In the third clone analyzed, the invasive capacity decreased during culture, in parallel with decreased expression of stromelysin-1. The low level of stromelysin-1 expression observed in this cell line did not result from loss of AP-1-transcription-factor activity, and was not reversed by phorbol-ester treatment.

Adenovirus Early Proteins↗
PubMed1992

The carboxy-terminal exon of the adenovirus E1A protein is required for E4F-dependent transcription activation.

The adenovirus-2 E1A 289R transcription activator protein contains a 49 amino acid sequence (designated CR3) that has been suggested to represent the minimal domain required for E1A-induced activation of viral early transcription. We show here that the non-conserved carboxy-terminal E1A exon contains two interchangeable elements that are required for efficient CR3-dependent transactivation of the adenovirus E4 promoter in HeLa cells. These two elements do not encode independent transactivation functions and have been designated auxiliary regions (ARs) 1 and 2. The effects of AR1 and AR2 are not additive, suggesting that they contribute a mechanistically analogous function in transcription. Previous studies have suggested that two cellular transcription factors, ATF-2 and E4F, can function together with E1A to induce transcription of the E4 promoter. The importance of respective factors for E4 transcription has not been resolved. We find that E1A activation of E4F, but not ATF-2 (or other ATF factors), is AR1- and AR2-dependent. This result suggests that E1A induction of the E4 promoter in HeLa cells is primarily mediated by E4F.

Activating Transcription Factors↗
PubMed1992

Clinical relevance of tumour markers CA 19-9 and CA-50 in sera from patients with pancreatic duct carcinoma.

Serum levels of the tumour antigens CA 19-9 and CA-50 and their relation to the extent of the disease were studied in 97 patients with carcinoma of the pancreas. Of 13 patients with normal serum concentrations of CA 19-9, 11 (84.6%) had irresectable disease, whereas 87.5% of the patients with resectable disease expressed antigen levels above cut-off. Following attempted radical surgery, preoperatively elevated serum levels decreased in eight patients (50%). Unchanged and high levels were associated with residual disease and early death. Clinical signs of recurrence were preceded by elevated serum levels of both tumour antigens.

Aged↗
PubMed1992

Enhanced invasive properties of rat embryo fibroblasts transformed by adenovirus E1A mutants with deletions in the carboxy-terminal exon.

E1A genes deficient in the carboxy-terminal exon can cooperate with activated ras oncogenes to induce transformation of rat embryo fibroblasts. However, the resulting transformed foci show a distinct appearance characterized by a decreased adhesion of the cells to the substrate. Here, we demonstrate that cell lines derived from foci showing the variant morphology are defective in down-regulation of stromelysin 1 metalloprotease expression and show an increased invasive propensity compared with cells transformed by wild-type E1A. The altered focus morphology, the high invasive propensity and the elevated stromelysin 1 expression were abrogated by glucocorticoid treatment. Our results show that E1A functions necessary for transformation and inhibition of invasive properties may be separated, and indicate that a 23 amino acid serine/threonine-rich region within the E1A carboxy-terminal exon is required for efficient repression of metalloprotease expression in transformed cells.

Adenovirus Early Proteins↗
PubMed1991

Duodenal varicose veins.

Duodenal varices (DV) are rare. We present a review of published cases with emphasis on the management and outcome, as illustrated by our own cases, which reflects the experience reported in the literature. The diagnosis of DV must be considered in patients with gastrointestinal bleeding. Two-thirds of all reported cases have portal venous hypertension caused by hepatic cirrhosis. In the remaining one-third prehepatic portal hypertension as a consequence of either a compromised portal venous circulation (caused by perivenous tumor or inflammation) or a primary haematological disease is the underlying cause. Previously, duodenoscopy has often failed to detect and correctly interpret DV, and was similarly unsuccessful in our case. This case report demonstrates the problems and shortcomings in the management of DV and documents a hither to unreported cause. Treatment depends on the severity of bleeding. When conservative measures cannot control the haemorrhage, emergency laparotomy may be indicated. The type of surgery should be chosen according to the aetiology, site and extent of the bleeding DV. Among 112 reported cases of DV, information on outcome exists for only 35 patients who presented with haemorrhage. The aetiology was liver cirrhosis in 26 of these patients, 10 of whom had a fatal outcome, and prehepatic portal hypertension in the remaining 9, 1 of whom had a fatal outcome.

Adult↗
PubMed1991

Glucocorticoid hormones may partially substitute for adenovirus E1A in cooperation with ras.

The effects of hormonal promotion of T24-ras oncogene-transfected rat embryo fibroblasts (REF) were compared to cotransformation of these cells with adenovirus E1A and ras. Cotransfection of E1A + ras resulted in the appearance of morphologically transformed cells which were very efficiently established into cell lines. Addition of glucocorticoid hormones to T24-ras-transfected REF cells resulted in cells with a transformed morphology and a capacity to form foci. These foci were, however, inefficiently established into stable cell lines. Removal of hormone from growing cells resulted in retarded growth, suggesting that the hormone acted as a growth factor on these cells. Both E1A-transformed cells and hormone-treated ras-transformed cells showed a reduction in synthesis of high molecular weight tropomyosin isoforms and a decreased expression of surface fibronectin. Control experiments demonstrated that the effects of hormone were mediated through the glucocorticoid receptor. Our findings suggest that glucocorticoid hormones may promote the in vitro growth of ras-initiated REF cells into stably transformed cell lines, but that this ability is limited compared to that of adenovirus E1A.

Adenoviridae↗
PubMed1991

Independent transformation activity by adenovirus-5 E1A-conserved regions 1 or 2 mutants.

Two conserved regions (CR1 and CR2) on the adenovirus E1A proteins have previously been shown to be required for cooperation with the ras oncogene in the transformation of primary rodent cells. Sequences within these regions are essential for the ability of E1A to associate with the 105K product of the retinoblastoma susceptibility gene, p105-RB, as well as with other cellular proteins, including a 107K (p107) and a 300K (p300) species. In this paper, we show that CR1 mutants deficient in p300 binding and CR2 mutants with lost or reduced binding of p105-RB and/or p107 have a low, but not abolished focus formation activity. In contrast, CR1/CR2 double mutants were deficient in focus formation, suggesting that the transformation activities displayed by the single CR1 or CR2 mutants were due to an independent transformation activity by both CR1 and CR2. No strict correlation between p105-RB binding and E1A-mediated transformation was observed. The E1A enhancer repression function was found to correlate with the binding of p300 but not with E1A-mediated transformation. Complex formation between E1A and p107, similar to the p105-RB binding, required sequences within both CR1 and CR2. The CR2 sequences required for binding of p107K or p105-RB were overlapping, but not identical. Finally, a larger segment of CR2 was required for stable complex formation between E1A and phosphorylated forms of p105-RB or p107 compared to corresponding unphosphorylated species.

Adenovirus Early Proteins↗
PubMed1991

Pachymeningitis associated with a pulmonary nodule.

The authors report a case of hypertrophic pachymeningitis, a rare cause of spinal cord compression. In this patient, dural inflammation was associated with a histologically identical pulmonary lesion. Such an association has not been described previously and supports the hypothesis that this disease is related to other connective tissue disorders.

Humans↗
PubMed1990

[An unusual anaphylactic reaction following succinylcholine chloride in a 21-month-old child].

An anaphylactoid reaction occurring after the intravenous administration of succinylcholine in a 21-month-old child is reported. The clinical manifestations and signs were limited to the upper airways and eyelids. The child was not known to be allergic or atopic. The IgE level was normal. The search for specific anti-choline IgE antibodies was negative. The skin tests were strongly positive for succinylcholine. The physiopathological and immunoallergic differences between anaphylaxis and anaphylactoid reaction are briefly discussed.

Adenoidectomy↗
PubMed1990

Immortalization of primary cells by DNA tumor viruses.

Cellular senescence is characterized by a decline in sensitivity to growth factors resulting in cessation of cellular growth. The expression of cellular or viral oncogenes may result in the establishment of cell lines with unlimited proliferative potential ("immortalization"). A variety of viral and cellular oncogenes have been reported to immortalize cells, suggesting that multiple mechanisms may lead to an escape from senescence. Immortalization has been reported to occur as a result of an interaction of viral proteins with cellular suppressor gene products or may result from the elevated expression of "transforming" oncoproteins (such as the polyomavirus middle-t antigen). Here we speculate that a selection for cells with a further decreased probability of cell cycle withdrawal can occur during the growth of cells expressing viral early genes, resulting in a process of tumor progression. Explaining immortalization in terms of mitogenic stimulation due to the expression of viral oncogenes followed by genetic/epigenetic changes may help to explain why lytic DNA viruses have a biological activity which may not be necessary for their life cycle.

Animals↗
PubMed1990

Complete transformation of embryonal rat fibroblasts by polyomavirus occurs during passage in vitro.

The tumorigenicity of secondary rat embryo fibroblasts transfected with a plasmid harboring a replication origin-defective polyomavirus was found to increase during in vitro propagation. Thus, polyomavirus-transfected cells were found to be more than 10,000-fold more tumorigenic when injected into syngenic rats at 3 months after transfection compared to those injected at an earlier time point. Furthermore, most clones of polyomavirus-transfected cells did not grow in semisolid medium at 52 days after transfection but did grow at 95 days. Addition of glucocorticoid hormones, but not of 25% fetal calf serum, to the growth medium of the early passage cells resulted in limited anchorage-independent growth. An altered level of expression of a number of proteins was found in cells analyzed at different times after transfection. Notably, the expression of a component of the actin filament system, tropomyosin 2, was shown to decrease during growth in vitro. The development of a more fully transformed phenotype at late passages correlated with loss of the requirement for large T-antigen for growth. Thus, cells transfected with a polyomavirus mutant encoding a thermolabile large T-antigen did not grow at the restrictive temperature at 6 weeks after transfection, but grew well at 5 months after transfection. We suggest that these phenomena may be explained by assuming that establishment of rodent fibroblasts, and thereby sensitivity to transformation by middle T-antigen, is not an immediate consequence of expression of large T-antigen but occurs after a period of growth in vitro.

Animals↗
PubMed1990

A viable mouse polyomavirus mutant without immortalizing or transforming activities.

The polyomavirus mutant, dl1041, has a 375-base pair deletion. It removes most of the sequences that are unique to rodent polyomaviruses and encodes part of the large and middle T-antigens. The mutant was conditionally viable, although both the immortalizing and transforming functions of the T-antigens produced by this mutant were found to be defective. However, the dl1041 mutant was found to be capable of DNA replication in rapidly growing mouse 3T6 cells. In contrast, dl1041 DNA synthesis could not be detected in serum-deprived mouse 3T3 cells. In these cells, the low efficiency of dl1041 DNA replication could be attributed to deficiencies in both large and middle T-antigen, suggesting a link between the mitogenic and oncogenic activities of these proteins. Transfection of growing mouse 3T6 cells with dl1041 DNA resulted in the formation of infectious virus, demonstrating that the dl1041 mutant is able to complete an infection cycle. The ability to activate the viral late promoter in trans was retained by the dl1041 mutant large T-antigen, suggesting that immortalization and trans-activation of the late promoter represent two distinct activities of the protein. An essential element of the immortalizing activity in the large T-antigen polypeptide chain appeared to be in a segment consisting of amino acid residues 136-184, since the dl1041 deletion abolished the activity and the 184 amino acid residue N-terminal dl1354 fragment of large T-antigen retained the activity.

Animals↗