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S Eriksson

Publications and source records attributed to S Eriksson.

At least 217 records · Page 12Linked to original sources
PubMed1995

In vitro fibril formation from alpha 1-antitrypsin-derived C-terminal peptides.

Fragments from various proteolytically degraded precursor proteins can form beta-amyloid fibrils. We studied, by electron microscopy and quantitative Congo red binding, the ability of three synthetic peptides, corresponding to residues 359-374 (C-36), 370-374 (C-5) and 375-394 (C-20) from the C-terminal part of alpha 1-antitrypsin (AAT) to form beta-amyloid fibrils in vitro. The peptides C-36 and C-5 had a pronounced tendency to form fibrils. C-20 lacked this property, suggesting that residues 359-375 and/or 370-374 are most critical for fibril formation. Native AAT added to peptide 125I-C-36 could bind and form complexes with the peptide, resulting in inhibition of amyloid fibril formation. Moreover, native AAT added to preformed fibrils induced disaggregation of fibrillar structures. The structural rearrangements of AAT that occurred during this 'autointeraction' included polymerization of the serpin, and an increase of its thermal stability. Also, following interaction, an increase (20-40%) of AAT's antielastase activity was noted. The demonstration of an in vitro beta-amyloid fibril formation from the AAT derived C-terminal peptides C-36 and C-5 and its regulation by the intact AAT molecule may have important in vivo implications.

Amino Acid Sequence↗
PubMed1995

Role of phosphodiesterase III in the antilipolytic effect of insulin in vivo.

The effect of three types of phosphodiesterase (PDE) inhibitors on in vivo antilipolysis was investigated in healthy subjects using a 2-h euglycemic, hyperinsulinemic (40 mU.m-2.min) clamp together with microdialysis of abdominal subcutaneous adipose tissue. During hyperinsulinemia (approximately 330 pmol/l), the circulating glycerol concentration was reduced to approximately 50% of the basal level of 53.2 +/- 3.6 mumol/l, indicating an antilipolytic effect. The decrease in adipose tissue dialysate glycerol, which mirrors the change in interstitial glycerol concentration, was about 40% during hyperinsulinemia when Ringer's solution alone was perfused. Local perfusion with a selective PDE IV inhibitor, rolipram (10(-4) mol/l), did not influence the insulin-induced decrease in dialysate glycerol (F = 0.8 vs. perfusion with Ringer's solution by two-factor analysis of variance [ANOVA]), although rolipram increased the dialysate glycerol level by 144 +/- 7% of the baseline value. However, local perfusion with a selective PDE III inhibitor, amrinone (10(-3) mol/l), or a nonselective PDE inhibitor, theophylline (10(-2) mol/l), abolished the ability of insulin to lower dialysate glycerol (F = 16.5, P < 0.01 and F = 8.5, P < 0.01, respectively, as compared with perfusion with Ringer's solution). The findings could not be explained by changes in the local blood flow (as measured by a microdialysis--ethanol escape technique), which was not affected by hyperinsulinemia in the presence or the absence of PDE inhibitors in the dialysis solvent. We conclude that PDEs play an important role in mediating the antilipolytic effect of insulin in vivo and that PDE III is the dominant isoenzyme modulating this effect.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1995

Induction of resistance to 2',2'-difluorodeoxycytidine in the human ovarian cancer cell line A2780.

2',2'-Difluorodeoxycytidine (gemcitabine; dFdC) is a nucleoside analog with promising antitumor activity. To be active it must be phosphorylated by deoxycytidine kinase (dCK). We induced resistance to gemcitabine in the human ovarian carcinoma cell line A2780 by exposure to increasing concentrations of gemcitabine. At 72 hours' exposure the IC50, defined as the concentration of gemcitabine causing 50% growth inhibition, increased from 0.6 nmol/L gemcitabine in A2780 to 92 mumol/L in the resistant variant, AG6000. AG6000 is cross-resistant to other drugs that require activation by dCK, such as I-beta-D-arabinofuranosylcytosine, 5-aza-2'-deoxycytidine, and 2-chlorodeoxyadenosine. AG6000 was also cross-resistant to 2',2'-difluorodeoxyuridine (dFdU), the deamination product of gemcitabine. In addition, cross-resistance to the multidrug-resistance drugs doxorubicin and vincristine was observed. This was not associated with induction of P-glycoprotein. No accumulation of gemcitabine triphosphate could be detected in AG6000 cells, in contrast to the parental A2780 cells. There was no specific dCK activity in extracts from AG6000 cells. Western blot analysis using a polyclonal anti-dCK antibody did not reveal any dCK protein in AG6000 cell extracts. Reverse transcribed and polymerase chain reaction amplified mRNA, using specific dCK primers, demonstrated that AG6000 expressed a normal length amplicon of 701 base pairs, besides an aberrant amplicon of 500 base pairs. Although the resistant cell line is routinely cultured in 6 mumol/L gemcitabine, the resistant phenotype can be maintained for at least 10 passages without gemcitabine. These results indicate that the gemcitabine resistance phenotype is stable and mainly due to dCK deficiency.

Antibiotics, Antineoplastic↗
PubMed1995

Omeprazole and H2-receptor antagonists in the acute treatment of duodenal ulcer, gastric ulcer and reflux oesophagitis: a meta-analysis.

This paper is a meta-analysis of 30 published, double-blind clinical trials comparing omeprazole with ranitidine or cimetidine for the treatment of duodenal ulcer, gastric ulcer and reflux oesophagitis. These studies compare the recommended doses of omeprazole with those for ranitidine and cimetidine, and the confidence intervals for the therapeutic gain show that the findings are highly reliable. The difference in healing rates favoured omeprazole over ranitidine in patients with duodenal ulcer after 2 weeks of treatment (15.2 percentage units; P < 0.001), and after 4 weeks of treatment in patients with gastric ulcer (9.9 percentage units; P = 0.005), or reflux oesophagitis (23 percentage units; P < 0.001). Similarly, omeprazole gave a 20.6 percentage units higher average healing rate than cimetidine in patients with duodenal ulcer after 2 weeks of treatment (P < 0.0001). Significantly more patients treated with omeprazole were free of symptoms at their first follow-up visit than patients treated with ranitidine or cimetidine.

Adult↗
PubMed1995

Ultrasonographic findings after conservative treatment of acute appendicitis and open appendicectomy.

In a randomized study we investigated the effects of antibiotics as the only treatment in acute appendicitis. Forty patients were examined, 19 after antibiotic treatment (one operated due to perforation) and 21 after surgery. All patients were examined prior to randomization, after 10 days and after 30 days. Of the positive ultrasonographic (US) findings, 18 (86%) of the 21 operated patients had histologically proven acute appendicitis. At the 10th day, 9 patients had a seroma under the scar, which had disappeared a month after surgery in all patients. In the 19 patients conservatively treated with antibiotics, the appendix could be visualized in 8 symptom-free cases on the 10th day. In 5 of the 8 patients the appendix was still visualized after 1 month. Three of these 5 had recurrent appendicitis within a year. It is concluded that US can be used not only in diagnosing acute appendicitis, but also in the evaluation of treatments such as antibiotics.

Acute Disease↗
PubMed1995

Sensitivity of interleukin-6 and C-reactive protein concentrations in the diagnosis of acute appendicitis.

OBJECTIVE: To evaluate the interleukin-6 (IL-6) concentration in the diagnosis of acute appendicitis, either as a single or four-hourly test. DESIGN: Open study. SETTING: Teaching hospital, Sweden. SUBJECTS: 165 consecutive patients admitted with suspected acute appendicitis. MAIN OUTCOME MEASURES: Correlation of concentrations of IL-6 and C-reactive protein with white cell count, duration of symptoms, and histological appearance of the appendix. RESULTS: Of 165 patients, 101 patients had their appendices removed, and of these 86 had histologically confirmed appendicitis. An IL-6 concentration of less than 15 ng/l was accepted as the reference. On admission IL-6 concentrations above 15 ng/l gave a sensitivity of 66% and a specificity of 31% for acute appendicitis. Repeated tests were of no value. When the patients operated on were divided in groups depending on the duration of symptoms, C-reactive protein was the most valuable test after 24 hours' abdominal pain. Total white cell count has the most sensitive in patients with abdominal pain of less than 24 hours' duration. CONCLUSIONS: Measurement of IL-6 concentrations does not increase the accuracy of the diagnosis of acute appendicitis. There was no significant correlation between IL-6 and C-reactive protein concentrations.

Acute Disease↗
PubMed1995

Leucocyte elastase as a marker in the diagnosis of acute appendicitis.

OBJECTIVE: To investigate the value of measuring the activity of the leucocyte elastase complex in plasma in the diagnosis of acute appendicitis, either as a single or four-hourly test. DESIGN: Open study. SETTING: Teaching hospital, Sweden. SUBJECTS: 165 consecutive patients admitted with suspected acute appendicitis. MAIN OUTCOME MEASURES: Correlation of concentrations of leucocyte elastase complex (elastase) and total white blood cell count (WBC) with C-reactive protein concentration and histological appearance of the appendix. RESULTS: Of 165 patients, 101 patients had their appendixes removed, and of these 86 had histologically confirmed appendicitis. An elastase value of less than 54 micrograms/l was considered to be the reference range. Elastase activity measured on admission gave a sensitivity of 61% and a specificity of 43% for acute appendicitis compared with the WBC which had a sensitivity of 81% and a specificity of 36%. The above blood tests were taken on two or more occasions four hourly after admission in 29 patients. Appendicitis was found in 25 of the 29 cases (87%), in which repeated tests showed a significant reduction in WBC together with a definite but not significant reduction in the elastase activity during the preoperative period. Repeated tests were of no value. CONCLUSIONS: Measurement of the leucocyte elastase complex in plasma does not increase the accuracy of the diagnosis of acute appendicitis. There was no significant correlation between the leucocyte elastase activity and the total white cell count.

Acute Disease↗
PubMed1994

2 cloning and expression of mouse deoxycytidine kinase. Pure recombinant mouse and human enzymes show differences in substrate specificity.

A cDNA encoding mouse deoxycytidine kinase (dCK) (EC 2.7.1.74) was cloned from a mouse T-cell lambda ZAP cDNA library. An insert of 2.8 kilobases (kb) contained the entire coding sequence of 780 base pairs. The protein coding sequence was 88% homologous at the nucleotide level with human dCK cDNA (Chottiner, E. G., Shewach, D. S., Datta, N. S., Ashcraft, E., Gribbin, D., Ginsburg, D., Fox, I. H., and Mitchell, B. S. (1991) Proc. Natl. Acad. Sci. U. S. A. 88, 1531-1535). At the amino acid level the homology was greater with only 16 of the 260 amino acids being different. Northern blot analyses revealed a size of 3.4 kb for mouse dCK mRNA as compared with 2.8 kb for human dCK. Part of the 3'-untranslated region was conserved between human and mouse dCK cDNA in contrast to the remainder of the 3'-sequence which was unrelated and about 500 nucleotides longer in mouse dCK cDNA. Mouse dCK cDNA showed cross-hybridization with several bands in EcoRI-digested genomic DNA from seven different mammalian species and chicken but not with yeast DNA. Both mouse and human dCK were cloned into the T5 promotor pQE30 vector system, expressed in Escherichia coli and purified to homogeneity. The kinetic constants for dCyd phosphorylation were similar for the human and mouse enzymes and also similar to what previously has been observed for dCK purified from human tissues. Mouse dCK was less efficient with regard to dAdo, dGuo, and ddCyd phosphorylation as compared with human dCK when using ATP as phosphate donor in a phosphoryl transfer assay.

Amino Acid Sequence↗
PubMed1994

Development and molecular characterization of a 2',2'-difluorodeoxycytidine-resistant variant of the human ovarian carcinoma cell line A2780.

2',2'-Difluorodeoxycytidine (gemcitabine, dFdCyd) is a deoxycytidine analogue with promising antitumor activity. In order to be active it must be phosphorylated by deoxycytidine kinase (dCK). We induced resistance to dFCyd in the human ovarian carcinoma cell line A2780 by exposure to increasing concentrations of dFdCyd. The IC50, defined as the concentration of dFdCyd causing 50% growth inhibition, at 72 h exposure increased from 0.6 nM dFdCyd in A2780 to 92 microM in the resistant variant, named AG6000. Although the resistant cell line is routinely cultured in 6 microM dFdCyd, the resistant phenotype can be maintained for at least 10 passages without dFdCyd. AG6000 is cross-resistant to other drug which require activation by dCK, such as 1-beta-D-arabinofuranosylcytosine, 5-aza-2'-deoxycytidine, and 2-chlorodeoxyadenosine. There was no specific dCK activity in extracts from AG600 cells. Western blot analysis using a polyclonal anti-dCK antibody did not reveal any dCK protein in AG6000 cell extracts. Reverse-transcribed and PCR-amplified mRNA, using specific dCK primers, demonstrated that AG6000 expressed a normal length amplicon of 701 base pairs, besides an aberrant amplicon of 500 base pairs. Chromosome spreads from the cell lines showed no major differences between A2780 and AG6000. The latter cell line was also cross-resistant to 2',2'-difluorodeoxyurdine, the deamination product of dFdCyd. Additionally, cross-resistance to the multidrug resistant drugs doxorubicin and vincristine was observed. This was not associated with the induction of P-glycoprotein, as determined by the RNase protection assay. Injection of AG6000 cells s.c. into nude mice demonstrated that the cell line had retained its tumorigenicity; AG6000 xenografts were not sensitive to dFdCyd treatment, in contrast to the parental A2780 tumors. No dFdCyd triphosphate accumulation was found in the resistant tumors, in contrast to the parental A2780 tumors. These results indicate that the dFdCyd resistance phenotype is stable, and mainly due to dCK deficiency.

Animals↗
PubMed1994

The interaction of hydrophobic bile acids with the alpha 1-proteinase inhibitor.

An in vitro complex formation between cholesterol and human alpha 1-proteinase inhibitor (alpha 1-antitrypsin, alpha 1-Pi) has been described. Hydrophobic bile acids were studied for a similar interaction using lithocholic acid (LC) as a prototype of a hydrophobic acid. At a molar ratio of 5:1, LC induced conformational changes of alpha 1-Pi reflected in an abnormal gel-electrophoretic appearance, loss of anodal immunoreactivity on crossed immunoelectrophoresis, exposition of new antigenic determinant(s) on immunodiffusion, and loss of antiproteinase activity. After 6 h incubation, LC and alpha 1-Pi form a complex of approximately 200 kDa molecular mass seen following gel-filtration. After prolonged (24 h) interaction a series of large alpha 1-Pi polymers were seen on SDS-PAGE under reducing conditions followed by Western blotting. Glycolitho-, sulfolitho-, deoxycholic and 3-beta-hydroxy-5-cholenoic acids induced similar but less pronounced changes of alpha 1-Pi, whereas transferrin remained unaffected. Hydrophilic acids lacked effect on alpha 1-Pi. The results are compatible with a specific, irreversible interaction of alpha 1-Pi with hydrophobic bile acids affecting its physical and proteinase inhibitory properties. The cholestatic potency of the hydrophobic acids studied and their ability to induce alpha 1-Pi polymerization may be important in cholestatic conditions.

Animals↗
PubMed1994

Induction of DNA strand breaks by ethylene oxide in human diploid fibroblasts.

In vitro exposure of normal human diploid fibroblasts (strain VH-10) to ethylene oxide (EtO) induced DNA strand breaks in the dose range of 2.5-30 mMh of EtO. Alkaline DNA unwinding (ADU), neutral filter elution (NFE), pulsed field gel electrophoresis (PFGE), and the comet assay were used to measure DNA single (SSBs) and double strand breaks (DSBs). Different induction rates of SSBs and DSBs, depending on applied method and also on treatment conditions (cells in monolayer or in suspension were used), were found. A dose-dependent increase of DNA strand breaks was found by the ADU method in the dose range of 2.5-20 mMh of EtO when treatment was performed in monolayer and in suspension. DSBs were detected by NFE only when the cells were treated with EtO in suspension (doses 10-30 mMh). The highest induction rate of DSBs (about 4 DSBs per 100 Mbp per 1 mMh of EtO) was detected in suspension with PFGE applied. We have shown that heat-labile sites are formed by EtO. Presumably, the different DSB levels detected by PFGE and NFE result from the conversion of these sites to DSBs during cell lysis at elevated temperature in the PFGE method. The results of the comet assay confirmed that apoptotic processes are not involved in the formation of DSBs in our experimental conditions (less than 1% of apoptotic cells were observed at all doses studied). Possible mechanisms for the induction of DNA strand breaks by EtO-treatment are discussed. The capacity to repair DSBs in EtO-exposed (5-7.5 mMh) cells was studied, and it was found that a considerable part of the damage (about 50%) could be repaired during 18 hr of incubation.

Cells, Cultured↗
PubMed1994

Properties and levels of deoxynucleoside kinases in normal and tumor cells; implications for chemotherapy.

Deoxynucleoside kinases are key enzymes in deoxyribonucleoside salvage, activating several clinically important chemotherapeutic drugs. The four known kinases, cytosolic thymidine kinase (TK1) and deoxycytidine kinase (dCK) and the mitochondrial thymidine kinase (TK2) and deoxyguanosine kinase (dGK), have been purified and characterized as to the subunit structure as well as specificity with a large number of analogs. These results are summarized and used to establish selective assays for the four enzymes in crude extracts of normal and malignant human peripheral blood mononuclear cells, gastrointestinal tissues and sarcomas. TK2 and dGK activities were found at low levels in all tissues, possibly correlated to the content of mitochondria. TK1 activity was detected only in samples containing a significant number of S phase cells. We have measured dCK activity as well as dCK polypeptide level by immuno blotting in these extracts. High levels of dCK were found in normal mononuclear leukocytes (91-145 ng dCK/mg protein) and in B-cell chronic lymphocytic leukemia (80 +/- 30 ng/mg, n = 23). Hairy cell leukemia contained lower levels (28 +/- 23 ng/mg, n = 7), as did unexpectedly three samples of T-cell chronic lymphocytic leukemia (18 +/- 14 ng/mg). Phytohemaglutinine stimulation of normal lymphocytes did not lead to any substantial increase in either dCK activity or expression (less than 2.5-fold). In colon adenocarcinomas, the dCK content was significantly higher (21 +/- 9.3 ng/mg, n = 20) than in normal colon mucosa (8.2 +/- 3.7 ng/mg, n = 19, p < 0.05). A similar pattern of dCK expression was found in gastric adenocarcinomas (21 +/- 13 ng/mg, n = 5) and normal ventricular mucosa (6.2 +/- 5.4 ng/mg, n = 5, p < 0.15). One leiomyosarcoma and one extra-skeletal osteosarcoma showed a dCK levels comparable to those found in normal lymphocytes (84 +/- 6 and 109 +/- 4 ng/mg), while other sarcoma samples contained levels comparable to the gastrointestinal adenocarcinomas (20 +/- 7 ng/mg, n = 12). We confirm that dCK is expressed constitutively and predominantly in lymphoid cells, but conclude that a significant expression may be found in non-lymphoid tissues as well, with increased levels in the corresponding tumor tissue. 2-Chlorodeoxyadenosine (CdA), an antileukemic agent used in treatment of hairy cell leukemia and chronic lymphocytic leukemias (B-CLL), is phosphorylated by dCK which was used as the selective substrate for this enzyme. A study was performed to investigate if there was a correlation between the dCK levels and the response to CdA treatment.(ABSTRACT TRUNCATED AT 400 WORDS)

Adenocarcinoma↗
PubMed1994

Protection of rhesus macaques from SIV infection by immunization with different experimental SIV vaccines.

The immunogenicity and efficacy of an inactivated whole SIVmac (32H) preparation adjuvanted with muramyl dipeptide (SIV-MDP) and a gp120-enriched SIVmac (32H) ISCOM preparation (SIV-ISCOM), were compared by immunizing four rhesus macaques (Macaca mulatta) four times with SIV-MDP and four others in the same way with SIV-ISCOM. Two monkeys immunized with whole inactivated measles virus (MV) adjuvanted with MDP (MV-MDP) and two monkeys immunized with MV-ISCOM served as controls. In the SIV-ISCOM-immunized monkeys higher SIV-specific serum antibody titres were found than in the SIV-MDP-immunized monkeys. In contrast to the MV-immunized monkeys all SIV-MDP- and SIV-ISCOM-immunized monkeys were protected against intravenous challenge 2 weeks after the last immunization with 10 median monkey infectious doses (MID50) of a cell-free SIVmac (32H) challenge stock propagated in the human T-cell line C8166. After 43 weeks the protected monkeys were reboosted and 2 weeks later rechallenged with 10 MID50 of the same virus produced in peripheral blood mononuclear cells (PBMC) from a rhesus macaque. None of these animals proved to be protected against this challenge. In a parallel experiment in which the same numbers of monkeys were immunized in the same way, the animals were challenged intravenously with 10 MID50 of PBMC from an SIVmac (32H)-infected rhesus macaque. Two out of four SIV-MDP- and two out of four SIV-ISCOM-immunized monkeys proved to be protected from SIV infection.

Animals↗