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Biomedical subjects

S Linder

Publications and source records attributed to S Linder.

At least 91 records · Page 5Linked to original sources
PubMed1996

Inhibition of tumor cell growth by monoterpenes in vitro: evidence of a Ras-independent mechanism of action.

(+)-Limonene (d-limonene) and related monoterpenes show chemopreventive activity against rodent mammary carcinoma and inhibit the growth of cancer cells in vitro. One suggested mechanism for the anti-tumorigenic effect of (+)-limonene is inhibition of the post-translational isoprenylation of growth controlling Ras oncoproteins. We have here examined the growth inhibitory effect of (+)-limonene and other related monoterpenes on PANC-1 pancreas carcinoma cells (carrying a K-ras mutation) and on 12V-H-ras-transformed rat fibroblasts. (+)- and (-)-perillyl alcohol, 7-methyl-perillyl alcohol, (+)-limonene oxide and (+)-perillic acid methyl ester were all found to efficiently inhibit cell growth at 1 mM, whereas (+)-limonene caused an approximately 50% growth reduction at 5 mM. Whereas BZA-5B, an inhibitor of Ras farnesyl transferase, was found to induce morphological reversion of 12V-H-ras-transformed cells, (+)-perillyl alcohol and (+)-limonene did not induce reversion. Furthermore, monoterpenes did not decrease MAP kinase enzyme activity or collagenase promoter activity in PANC-1 cells, two functions known to be down-stream from Ras. We conclude that although effective in inhibiting the growth of tumor cells harboring activated ras oncogenes, limonene and (+)-perillyl alcohol are unlikely to act by inhibiting Ras function.

Alkyl and Aryl Transferases↗
PubMed1996

A short peptide eluted from the H-2Kb molecule of a polyomavirus-positive tumor corresponds to polyomavirus large T antigen peptide at amino acids 578 to 585 and induces polyomavirus-specific immunity.

A short peptide in complex with the H-2Kb molecule on PyRMA, a polyomavirus transfectant of the mouse lymphoma cell line RMA, was identified as a polyomavirus tumor-specific transplantation antigen. The peptide was obtained by affinity chromatography, acidic extraction, and reverse-phase high-pressure liquid chromatography (HPLC). In one HPLC fraction, a peptide sequence in which 5 of 8 amino acids, GKxGLxxA, corresponded to residues 578 to 585 of polyomavirus large T antigen was identified. In tumor rejection assays, we therefore tested three related synthetic peptides, corresponding to the octapeptide LT 578-585, GKTGLAAA; the nonapeptide LT 578-586, GKTGLAAAL; and the decapeptide LT 578-587, GKTGLAAALI. The octapeptide was found to give the most effective immunization against the outgrowth of the polyomavirus DNA-positive PyRMA tumor. However, none of the three peptides immunized against the original polyoma-virus-negative RMA line.

Amino Acid Sequence↗
PubMed1995

The DNA binding domains of the yeast Gal4 and human c-Jun transcription factors interact through the zinc-finger and bZIP motifs.

Different Gal4 fusion proteins, expressing unrelated transcription activator domains, were found to activate transcription from promoters containing dimerized AP1 DNA binding sites. Transactivation was dependent on the first 74 amino acids of Gal4. A direct interaction between Gal4 and c-Jun was demonstrated using a GSTGal4 fusion protein and in vitro translated human c-Jun. The interaction required the zinc finger containing DNA binding domain of Gal4 and the basic-leucine zipper region of c-Jun. These results demonstrated that the specificity of Gal4 fusion proteins in transient transfection experiments in mammalian cells is not restricted to reporters containing Gal4 binding sites, but also includes promoters containing AP1 binding sites. Furthermore, the Gal4 fusion proteins also activated transcription from a pUC18 vector fragment containing several putative AP1 binding sites. Finally, our results indicate that Gal4 activator proteins binding to Gal4 binding sites and to DNA bound AP1 factors can co-operatively activate transcription.

Base Sequence↗
PubMed1995

Sample preparation of human tumors prior to two-dimensional electrophoresis of proteins.

Sample preparation procedures are critical for obtaining high quality two-dimensional electrophoresis (2-DE) separations from clinical tumor materials. In this communication, we describe procedures which we have found satisfactory for preparing various tumor samples for 2-DE. By these procedures, tumor cells are enriched from serum proteins and contaminating stromal cells. Tumors can be prepared with good reproducibility to obtain high resolution using these techniques.

Electrophoresis, Gel, Two-Dimensional↗
PubMed1995

Combined use of nuclear morphometry and DNA ploidy as prognostic indicators in nonresectable adenocarcinoma of the pancreas.

The introduction of combined modality treatment has only marginally affected the prognosis in nonresectable pancreatic carcinoma. Evaluation of easily accessible prognostic variables could be of clinical importance when selecting patients for proper therapy. DNA ploidy and morphometric variables were chosen as prognostic markers and assessed on cytologic material obtained by fine-needle aspiration biopsy (FNAB) from 128 patients with pancreatic carcinoma. The nuclear DNA content was measured by image cytometry. Patients were categorized as short-term (< or = 6 mo) and long-term survivors (> 6 mo). Ninety-eight of 116 nonresectable patients were possible to evaluate. There were significant differences between short- and long-term survivors with regard to DNA ploidy (p < 0.01) and the morphonuclear variable anisokaryosis (p < 0.001). In patients with either DNA aneuploid tumors or anisokaryosis > or = 0.6, the survival time was 6 mo or less in 85 and 93%, respectively. When both these criteria were fulfilled, only 5% survived for more than 6 mo. Thus, DNA ploidy and morphometry, separately or in combination, may provide prognostic information in nonresectable pancreatic carcinoma.

Adenocarcinoma↗
PubMed1995

Variation in the ratio of shoot silhouette area to needle area in fertilized and unfertilized Norway spruce trees.

We compared the range and variation in shoot silhouette area to projected leaf area ratio (SPAR) in fertilized and unfertilized (control) Norway spruce (Picea abies (L.) Karst.) trees. We measured SPAR for several view directions of 169 shoots at different depths in the crown of fertilized and control trees. There was an increase in SPAR with depth in the crown in both control and fertilized trees. In the fertilized trees, however, mean SPAR was larger overall, the increase with depth in the crown was steeper, and there was a larger variation in SPAR with inclination and rotation angle of the shoot (relative to the view direction). In particular, shoots in the lower crown of fertilized trees were rotationally asymmetrical ("flat") and had high values of the maximum ratio of shoot silhouette area to projected leaf area (SPAR(max)). Differences in SPAR between fertilized and control trees were explained by changes in shoot structure in response to fertilization and shading. Shoots of fertilized trees were larger and had more needle area than shoots of control trees. However, the ratio of needle area to shoot size was smaller in fertilized trees than in control trees, implying less within-shoot shading and, consequently, a larger SPAR. Also, the increase in SPAR with increased shading (depth in the crown) could be explained by a decrease in the ratio of needle area to shoot size. In addition, because fertilized trees had more needle area than control trees, the effect of shading at a given depth in the crown was more pronounced in fertilized trees than in control trees.

Journal Article↗
PubMed1995

Apoptosis and c-jun induction by cisplatin in a human melanoma cell line and a drug-resistant daughter cell line.

Cisplatin resistance was developed in the human melanoma cell line RPMI8322 by repeated short-term exposures to cisplatin. The most resistant daughter cell line, RPMI8322/CDDP-300, was 4-fold resistant to cisplatin, and partially cross-resistant to carboplatin, melphalan and UV, but not to BCNU. RPMI8322/CDDP-300 cells showed less apoptosis after cisplatin than the parental cells. The cisplatin resistance was not paralleled by a similar reduction in cellular cisplatin accumulation or DNA cross-links in RPMI8322/CDDP-300 cells, and these cells exhibited no increase in cellular glutathione or in mRNA encoding the DNA excision repair protein ERCC1 and XPB. Induction of c-jun mRNA by cisplatin was considerably lower in RPMI8322/CDDP-300 cells than in RPMI8322 cells, consistent with the possibility that c-jun induction may be involved in a pathway that triggers apoptosis after exposure to DNA damaging agents. However, c-jun induction is not necessary for apoptosis, since cisplatin also induced apoptosis in A14 rat embryo fibroblasts, cells in which the c-jun gene is deleted.

Animals↗
PubMed1994

Correlation between stromelysin-3 mRNA level and outcome of human breast cancer.

The expression level of stromelysin-3 (ST3) mRNA was analyzed by in situ hybridization of formalin-fixed, paraffin-embedded primary breast-tumor samples from 76 patients. Digital image analysis of the dark-field in situ hybridization signal was used to measure the maximal level of ST3 expression in each tumor. All 55 invasive ductal carcinomas and 9 of 10 invasive lobular carcinomas were positive for ST3. Invasive tumors had significantly higher levels of ST3 than in situ tumors. Furthermore, ST3 levels were higher in invasive ductal carcinomas than in invasive lobular carcinomas. The ST3 expression level was significantly correlated to fatal metastatic disease (mean follow-up 104 months). ST3 levels of < 2,500 units were associated with distant metastasis in 46% of patients, whereas levels of > 2,500 units were associated with metastasis in 79% of patients selected for study. ST3 mRNA levels did not correlate with tumor size, microvessel density, DNA ploidy or estrogen-receptor levels. Studies of ST3 expression may provide information valuable for the understanding of breast cancer biology and for prognosis.

Adult↗
PubMed1994

Gallstone pancreatitis. The role of preoperative endoscopic retrograde cholangiopancreatography.

OBJECTIVES: To evaluate the efficacy of endoscopic retrograde cholangiopancreatography (ERCP) and laparoscopic cholecystectomy in patients with gallstone pancreatitis and to determine criteria predictive of common bile duct stones (CBDS). DESIGN: Retrospective chart review. PATIENTS: Seventy-one consecutive patients with gallstone pancreatitis. MAIN OUTCOME MEASURES: Identification and endoscopic management of CBDS, complications, and mortality. RESULTS: Preoperatively, ERCP revealed CBDS in seven of 22 patients and postoperatively, in five of six patients. All stones were successfully removed. Laboratory values and common bile duct dilatation on admission did not predict CBDS. Persistent hyperamylasemia (> 150 U/L) and persistent hyperbilirubinemia (> 29.07 mumol/L [1.7 mg/dL]) were associated with CBDS on ERCP or intraoperative cholangiography. All five patients with cholangitis underwent ERCP, and CBDS were found and removed in four. There were no deaths and there was a 7% complication rate. CONCLUSIONS: Gallstone pancreatitis can be effectively managed by selective ERCP, endoscopic sphincterotomy, and laparoscopic cholecystectomy. Preoperative ERCP can be restricted to patients with cholangitis, persistent hyperbilirubinemia, or persistent hyperamylasemia.

Adolescent↗
PubMed1994

Induction of the collagenase phorbol ester response element by staurosporine.

The indol alkaloid staurosporine is a potent inhibitor of protein kinase C, but has also been shown to have certain effects paradoxically similar to those of protein kinase C-activating phorbol esters. We show here that collagenase mRNA expression is stimulated by 10 nM staurosporine in normal and ras-oncogene-transformed rat fibroblasts. The kinetics of collagenase mRNA induction by staurosporine were slow compared to induction by phorbol ester. Staurosporine induction of the collagenase promoter appeared to be mediated via the TPA response element (TRE). Induction did not involve any increase in jun mRNA expression and did not require expression of c-Jun. Prolonged treatment with phorbol ester to deplete protein kinase C did not inhibit stimulation of the collagenase promoter by staurosporine. Instead, involvement of cAMP-dependent protein kinase (PKA) was indicated by inhibition of staurosporine induction by the PKA inhibitor H-89. In addition, raised levels of cAMP were observed during the first hour of staurosporine treatment. Altogether, our data indicate that staurosporine induces a PKA-dependent pathway leading to c-Jun-independent activation of the collagenase TRE element.

Alkaloids↗
PubMed1994

Oscillations in cytoplasmic free calcium concentration in human pancreatic islets from subjects with normal and impaired glucose tolerance.

Plasma insulin levels in healthy subjects oscillate and non-insulin-dependent diabetic patients display an irregular pattern of such oscillations. Since an increase in cytoplasmic free Ca2+ concentration ([Ca2+]i) in the pancreatic beta cell is the major stimulus for insulin release, this study was undertaken to investigate the dynamics of electrical activity, [Ca2+]i-changes and insulin release, in stimulated islets from subjects of varying glucose tolerance. In four patients it was possible to investigate more than one of these three parameters. Stimulation of pancreatic islets with glucose and tolbutamide sometimes resulted in the appearance of oscillations in [Ca2+]i, lasting 2-3 min. Such oscillations were observed even in some islets from patients with impaired glucose tolerance. In one islet from a diabetic patient there was no response to glucose, whereas that islet displayed [Ca2+]i-oscillations in response to tolbutamide, suggesting that sulphonylurea treatment can mimic the complex pattern of glucose-induced [Ca2+]i-oscillations. We also, for the first time, made patch-clamp recordings of membrane currents in beta-cells in situ in the islet. Stimulation with glucose and tolbutamide resulted in depolarization and appearance of action potentials. The islet preparations responded to stimulation with a number of different secretagogues with release of insulin. The present study shows that human islets can respond to stimulation with glucose and sulphonylurea with oscillations in [Ca2+]i, which is the signal probably underlying the oscillations in plasma insulin levels observed in healthy subjects. Interestingly, even subjects with impaired glucose tolerance had islets that responded with oscillations in [Ca2+]i upon glucose stimulation, although it is not known to what extent the response of these islets was representative of most islets in these patients.

Aged↗
PubMed1994

Prognostic significance of DNA ploidy in pancreatic carcinoma.

The nuclear DNA content was assessed by image cytometry on cytologic specimens obtained with fine-needle aspiration biopsy in 96 patients with pancreatic duct carcinoma. Twenty-two of these patients had pancreaticoduodenal resection. According to DNA analysis there were 27 (28%) diploid, 17 (18%) tetraploid, and 52 (54%) aneuploid tumors. The corresponding patient median survival times were 8, 5, and 4 months, respectively. Resectable tumors were more often DNA diploid (10 of 22) than nonresectable tumors (17 of 74) (p < 0.05). A Cox multivariate regression analysis demonstrated that surgical resection (p < 0.001) and diploid DNA pattern (p < 0.05) were factors associated with longer patient survival time. Although the difference in survival time was small, the data indicate that DNA diploid tumors represent a less aggressive subset of pancreatic carcinoma.

Adult↗
PubMed1994

Morphometric characteristics in adenocarcinoma of the pancreas and chronic pancreatitis.

BACKGROUND: Morphometric analysis whereby size and form of cellular nuclei are transformed into quantities has previously been shown to be a valuable adjunct to the histopathologic differential diagnosis between chronic pancreatitis and pancreatic carcinoma. The present study aims to assess the clinical value of morphometry performed on cytologic material from benign and malignant pancreatic lesions. METHODS: Cytologic specimens from 100 patients with the diagnosis of pancreatic carcinoma and 15 patients with chronic pancreatitis were evaluated by interactive morphometry using a digital image analyzer system. RESULTS: There were significant differences (p < 0.001) for all morphometric variables between the malignant and benign groups (mean area p 50, 135.41 microns 2 versus 69.66 microns 2; anisokaryosis, 0.74 versus 0.41; and polymorphism, 0.13 versus 0.09). CONCLUSIONS: Morphometry may be used as a complementary tool in the cytologic diagnosis of pancreatic carcinoma.

Adenocarcinoma↗
PubMed1994

Tumorigenic and metastatic properties of two ras-oncogene transfected rat fibrosarcoma cell lines defective in c-jun.

We here report the spontaneous loss of both homologues of the c-jun gene in two cell lines, isolated after transfection of rat embryo fibroblasts with single ras-oncogenes. These cells lines (designated A14 and B25) grow rapidly in vitro, have transformed morphologies and are invasive through reconstituted basal membranes. Both c-jun defective cell lines were found to be tumorigenic and metastatic in athymic mice. Loss of c-jun was paralleled by a dramatic decrease in interstitial collagenase expression, whereas stromelysin mRNA expression in c-jun- A14 and B25 cells was similar to that observed in c-jun+ transformed cell lines. Transient transfection experiments using reporter plasmids showed that stromelysin promoter activity in A14 cells was severely impaired by a point mutation in the -71 to -65 AP-1 motif, and was inhibited by a Jun dominant negative mutant. Gel mobility shift studies demonstrated the presence of a factor in A14 nuclear extracts capable of binding the stromelysin TRE. This factor bound JunB, JunD and Fos antibodies. Our findings suggest that c-Jun is not required for the tumorigenic and metastatic potential of ras-transformed fibrosarcoma cells, and that AP-1 protein(s) lacking c-Jun are capable of activating the stromelysin gene promoter.

Animals↗
PubMed1993

Chronic lymphocytic leukemia cells with allelic deletions at 13q14 commonly have one intact RB1 gene: evidence for a role of an adjacent locus.

We have previously shown that 30% of patients with B-cell chronic lymphocytic leukemia (B-CLL) have hemizygous deletions of the retinoblastoma (RB1) gene at 13q14. RB1 gene deletions may thus participate in malignant transformation of B-CLL, but it is also possible that a neighboring gene on 13q is the relevant one. To answer this question the remaining RB1 allele of eight clones with hemizygous deletions was studied by reverse transcription-polymerase chain reaction (RT-PCR), single-strand conformation polymorphism (SSCP) analysis, and immunofluorescense techniques. Cells from 10 patients without RB1 gene deletions were also studied by these methods. Lack of RB1 mRNA and RB protein expression was seen in leukemia cells from one of the patients. All other cases were found to be normal with regard to immunofluorescense, RT-PCR, and SSCP analysis, indicating at least one functional RB1 allele and supporting the importance of another gene in the 13q14 deletions. We then performed extended Southern blot analyses of the 13q region, using probes for 10 different loci. In 14 of 31 CLL clones (45%), deletions of a region telomeric to the RB1 gene (D13S25) were observed. In 4 of the cases the deletions were homozygous. Hemizygous deletions of the RB1 gene were observed in 11 of these patients and in none of the patients without D13S25 deletions. These data thus indicate that a gene(s) telomeric to RB1 is involved in the malignant transformation of CLL clones and that deletions of this region are a common event in this disease.

Base Sequence↗
PubMed1993

Biochemical evidence that phytochrome of the moss Ceratodon purpureus is a light-regulated protein kinase.

The phytochrome gene of the moss Ceratodon purpureus (phyCer) codes for a novel phytochrome polypeptide with a predicted molecular mass of 145 kDa that has a COOH-terminal domain which is homologous to the catalytic domain of eukaryotic protein kinases. In this paper we report the first biochemical evidence that in fact, as predicted from the gene sequence, PhyCer represents an active, light-regulated protein kinase. In vitro phosphorylation experiments with protonemata extracts revealed the existence of a 140 kDa protein, phosphorylated in a red/far-red light dependent manner. The binding of a polyclonal antibody directed to the protein kinase catalytic domain of PhyCer enhanced the phosphorylation of a 140 kDa band when assayed in a renaturation-auto-phosphorylation experiment with nitrocellulose bound protein. These findings strongly implicate that the phyCer gene product has protein kinase activity and is capable of auto-phosphorylation. The results of the renaturation-phosphorylation experiments were essentially the same, no matter whether protein extracts from light grown or dark adapted moss protonemata were used. Thus, phyCer expression most likely is not light regulated.

Genes↗