Biomedical subjects

S Eriksson

Publications and source records attributed to S Eriksson.

At least 91 records · Page 5Linked to original sources

PubMed2000

Dual-label time-resolved immunofluorometric assay of free and total prostate-specific antigen based on recombinant Fab fragments.

BACKGROUND: Recombinant Fab fragments are attractive as reagents for novel sandwich immunoassays, but no such assays have been described. We developed a dual-label two-site immunoassay based entirely on recombinant Fab fragments and compared it to the same assay with intact monoclonal antibodies. METHODS: The capture Fab fragment, which binds free prostate-specific antigen (PSA) and PSA in complex with alpha(1)-antichymotrypsin on an equimolar basis, is site-specifically biotinylated and attached to the solid phase in streptavidin-coated microtitration wells. The Fab fragment that detects only free PSA is site-specifically labeled with a fluorescent europium chelate, and the Fab fragment that detects both free and serpin-complexed PSA in an equimolar fashion is labeled with a fluorescent terbium chelate. Time-resolved fluorescence is used to measure both europium and terbium signals in one well. RESULTS: The detection limits of the assay (mean + 3 SD of zero calibrator) were 0.043 and 0.28 microgram/L, respectively, for free and total PSA. The within-run and day-to-day CVs were 2-11% and 4-10%, respectively. Mean recoveries were 93% and 98% in female and male sera, respectively. Compared with the commercial ProStatus PSA Free/Total Assay, the intercepts of the regression equations (r >0. 99) were not significantly different from zero, and the slopes were 0.95-1.01. In one female serum sample, PSA was falsely increased with the monoclonal assay but was undetectable with the recombinant assay. CONCLUSIONS: The performance of this novel assay based on recombinant components is comparable to a conventional assay based on monoclonal antibodies. The more complete control of the essential characteristics of site-specifically derivatized recombinant Fab fragments will be valuable for the design of miniaturized and multianalyte assay concepts where correct antibody orientation, density, and capacity as well as uncompromised binding affinity are required.

Antibodies, Monoclonal↗

PubMed2000

Enzymatic mutation detection in the P53 gene.

BACKGROUND: The enzymatic mutation detection (EMD) assay uses the bacteriophage resolvase T4 endonuclease VII, which cleaves preformed heteroduplex molecules at mismatch sites, forming two shorter fragments that can be resolved by gel electrophoresis. The method can be used to detect single and multiple base changes, as well as insertions and deletions. METHODS: The sensitivity, specificity, and positional accuracy of mutation detection by EMD with the PASSPORT(TM) Mutation Scanning Kit were assessed in a blind fashion for three analytical platforms (radioactive detection and automated laser sequencers ALFexpress and ABI PRISM 377). PCR products of 703 bp covering codons 188-393 of the P53 gene were prepared from colorectal tumor samples and analyzed by EMD; the results were compared to data from cDNA sequencing. A 1362-bp PCR product prepared from IL4r gene was used to test detection of multiple base changes in long PCR products. RESULTS: The sensitivity for detection of mutations using EMD exceeded 90%, and the specificity exceeded 80% on all analysis platforms. The method localized 90% of mutations to within two codons and four codons for automated laser sequencers and detection by radioactivity, respectively. The method detected at least five mismatches in heteroduplexes >1 kb. CONCLUSIONS: The EMD system facilitates efficient detection of genetic variation in fragments exceeding 1 kb irrespective of location and type. The technology is particularly well suited to the detection of mutations in genes frequently mutated at unpredictable locations.

Colorectal Neoplasms↗

PubMed1999

Stereoisomeric selectivity of human deoxyribonucleoside kinases.

Deoxynucleoside kinases catalyze the 5'-phosphorylation of 2'-deoxyribonucleosides with nucleoside triphosphates as phosphate donors. One of the cellular kinases, deoxycytidine kinase (dCK), has been shown to phosphorylate several L-nucleosides that are efficient antiviral agents. In this study we investigated the potentials of stereoisomers of the natural deoxyribonucleoside to serve as substrates for the recombinant cellular deoxynucleoside kinases. The cytosolic thymidine kinase exhibited a strict selectivity and phosphorylated only beta-D-Thd, while the mitochondrial thymidine kinase (TK2) and deoxyguanosine kinase (dGK) as well as dCK all had broad substrate specificities. TK2 phosphorylated Thd and dCyd stereoisomers in the order: beta-D- > or = beta-L- >> alpha-D- > or = alpha-L-isomer. dCK activated both enantiomers of beta-dCyd, beta-dGuo, and beta-dAdo with similar efficiencies, and alpha-D-dCyd also served as a substrate. dGK phosphorylated the beta-dGuo enantiomers with no preference for the ribose configuration; alpha-L-dGuo was also phosphorylated, and beta-L-dAdo and beta-L-dCyd were substrates but showed reduced efficiencies. The anomers of the 2',3'-dideoxy-D-nucleosides (ddNs) were tested, and TK2 and dCK retained their low selectivities. Unexpectedly, alpha-dideoxycytidine (ddC) was a 3-fold better substrate for dCK than beta-ddC. Similarly, alpha-dideoxythymidine (ddT) was a better substrate for TK2 than beta-ddT. dGK did not accept any D-ddNs. Thus, TK2, dCK, and dGK, similar to herpes simplex virus type 1 thymidine kinase (HSV-1 TK), showed relaxed stereoselectivities, and these results substantiate the functional similarities within this enzyme family. Docking simulations with the Thd isomers and the active site of HSV-1 TK showed that the viral enzyme may in some respects serve as a model for studying the substrate specificities of the cellular enzymes.

Binding Sites↗

PubMed1999

Molecular and biochemical mechanisms of fludarabine and cladribine resistance in a human promyelocytic cell line.

2F-Adenine arabinoside (fludarabine, Fara-A) and 2-chloro-2'-deoxyadenosine (cladribine, CdA) are nucleoside analogues with antineoplastic activity in vitro and in vivo. Lack of clinical resistance between CdA and Fara-A has been demonstrated in patients with chronic lymphocytic leukemia (G. Juliusson et al., N. Engl. J. Med., 327: 1056-1061, 1992). To clarify the differences in mechanism of resistance to CdA and Fara-A in vitro, we developed two stable, resistant cell lines, HL60/CdA and HL60/ Fara-A, by exposure to increasing concentrations of analogues over a period of 8 months. Resistant cells tolerated >8,000 and 5-fold higher concentrations of CdA and Fara-A, respectively. The specific activity of the nucleoside phosphorylating enzyme (using deoxycytidine as substrate) in cell extracts from HL60/CdA and HL60/Fara-A mutants was about 10 and 60%, respectively, compared with the parental cell line. Western blot analysis using a polyclonal antibody showed no detectable deoxycytidine kinase (dCK) protein in CdA-resistant cells, whereas in Fara-A-resistant cells, it was at the same level as in the parental cells. The mitochondrial enzyme deoxyguanosine kinase was not altered in resistant cell lines. The HL60/CdA cells showed cross-resistance to 2-chloro-2'-arabino-fluoro-2'-deoxyadenosine, Fara-A, arabinofuranosyl cytosine, difluorodeoxyguanosine, and difluorodeoxycytidine toxicity, most likely because of the decreased phosphorylation of these analogues by dCK. Using real-time quantitative PCR, the mRNA levels of dCK and cytosolic 5'-nucleotidase (5'-NT), a major nucleoside dephosphorylating enzyme, were measured. It was shown that the dCK mRNA levels in both CdA- and Fara-A resistant cells were decreased in parallel with the activity. The expression of 5'-NT mRNA was not significantly elevated in CdA- and Fara-A resistant cells, as compared with the parental cells. Ribonucleotide reductase maintains a balanced supply of deoxynucleotide triphosphate pools in the cell and may also be a major cellular target for CdA and Fara-A nucleotides. Except for the deoxycytidine triphosphate level, the intracellular deoxynucleotide triphosphate pools were significantly higher in Fara-A-resistant cells compared with the parental cell line. This might be a consequence of mutation or altered regulation of ribonucleotide reductase activity and may explain the 2-5-fold cross-resistance to several nucleoside analogues observed with HL60/Fara-A cells. It is likely that the resistance for CdA was mainly attributable to a dCK deficiency, and Fara-A-resistant cells might have another contributing factor to the resistance beyond the dCK deficiency.

Antineoplastic Agents↗

PubMed1999

A randomized trial of risperidone, placebo, and haloperidol for behavioral symptoms of dementia.

OBJECTIVE: To compare effects of risperidone with placebo (efficacy and tolerability) and haloperidol (tolerability) for treating demented patients with aggression and other behavioral symptoms. METHODS: A 13-week double-blind study involving 344 patients with dementia randomly assigned to receive placebo or flexible doses (0.5 to 4 mg/d) of risperidone or haloperidol. Behavioral symptoms were assessed by the Behavior Pathology in Alzheimer's Disease Rating Scale (BEHAVE-AD), the Cohen-Mansfield Agitation Inventory (CMAI), and the Clinical Global Impression (CGI) scale. Tolerability assessments included the Extrapyramidal Symptom Rating Scale, sedation levels, Functional Assessment Staging, Mini-Mental State Examination, and incidence of adverse events. RESULTS: The mean dose at endpoint was 1.1 mg/d of risperidone and 1.2 mg/d of haloperidol. Although not significant, a higher percentage of patients receiving risperidone than those receiving placebo showed clinical improvement (> or =30% reduction from baseline to endpoint in BEHAVE-AD total score) at endpoint and week 12. Reductions in the BEHAVE-AD total score were significantly greater with risperidone than with placebo at week 12. In a further analysis of aggression, the most dominant symptom in these patients, BEHAVE-AD and CMAI aggression cluster scores were significantly reduced compared with placebo at endpoint and week 12. CGI scores were also significantly reduced at endpoint and week 12. Severity of extrapyramidal symptoms with risperidone did not differ significantly from that of placebo and was less than that of haloperidol. A post hoc analysis showed significantly greater reductions in the BEHAVE-AD aggressiveness score with risperidone than haloperidol at week 12. CONCLUSION: Low-dose risperidone (mean 1.1 mg/d) was well tolerated and associated with reductions in the severity and frequency of behavioral symptoms, particularly aggression, in elderly patients with dementia.

Aged↗

PubMed1999

Cloning and characterization of mouse deoxyguanosine kinase. Evidence for a cytoplasmic isoform.

Deoxyguanosine kinase (dGK) is a nuclear gene product that catalyzes the phosphorylation of purine deoxyribonucleosides and their analogues. The human enzyme is located predominantly in the mitochondria, as shown by biochemical fractionation studies and in situ localization of the overexpressed recombinant protein. Here we describe the cloning of mouse dGK cDNA and the identification of a novel amino-terminally truncated isoform that corresponds to about 14% of the total dGK mRNA population in mouse spleen. In situ fluorescence assays suggest that the new isoform cannot translocate into the mitochondria and thus may represent a cytoplasmic enzyme. Expression of mouse dGK mRNA was highly tissue-specific and differed from the tissue distribution observed in humans. Recombinant mouse dGK showed similar specific activity and substrate specificity as compared with the human enzyme. The broad specificity, restricted tissue distribution, and location of mouse dGK in multiple cellular compartments raise new considerations with respect to the role of the individual deoxynucleoside kinases in nucleotide metabolism.

Amino Acid Sequence↗

PubMed1999

Synthesis of 5-(carboranylalkylmercapto)-2'-deoxyuridines and 3-(carboranylalkyl)thymidines and their evaluation as substrates for human thymidine kinases 1 and 2.

Derivatives of thymidine containing o-carboranylalkyl groups at the N-3 position and derivatives of 2'-deoxyuridine containing o-carboranylalkylmercapto groups at the C-5 position were synthesized. The alkyl spacers consist of 4-8 methylene units. The synthesis of the former compounds required 3-4 reaction steps in up to 75% overall yield and that of the latter 9-10 reaction steps with significantly lower overall yield. Derivatives of thymidine substituted with carboranylalkyl substituents at the N-3 position and short spacers were phosphorylated by both recombinant and purified cytosolic thymidine kinase (TK1) to a relatively high degree. None of the tested 2'-deoxyuridine derivatives possessing carboranyl substituents at the C-5 position were phosphorylated by either recombinant or purified TK1. The amounts of phosphorylation product detected for some of the C-5-substituted nucleosides with recombinant mitochondrial thymidine kinase (TK2) were low but significant and decreased with increasing lengths of the alkyl spacer. The data obtained in this study do not seem to support the tether concept applied in the synthesis of the new C-5- and N-3-substituted carboranyl nucleosides intended to reduce possible steric interference in the binding of carboranyl nucleosides with deoxynucleoside kinases. Instead, it appeared that a closer proximity of the bulky carborane moiety to the nucleoside scaffold resulted in better substrate characteristics.

Boron Compounds↗

PubMed1999

Effects of ethidium bromide on DNA loop organisation in human lymphocytes measured by anomalous viscosity time dependence and single cell gel electrophoresis.

The effects of ethidium bromide (EtBr) on human lymphocytes were studied by the method of anomalous viscosity time dependence (AVTD) and by the comet assay. EtBr at low concentrations increased the maximum viscosity and time of radial migration as measured with AVTD at neutral conditions of lysis. A pronounced relaxation of DNA loops was observed with the neutral comet assay. The maximal comet length corresponded to 2 Mb DNA loops. At high concentrations of EtBr, 2 mg/ml, significant reduction in AVTD below control level was seen that suggested hypercondensation of chromatin. The hypercondensation was directly observed with the neutral comet assay. EtBr did not induce DNA strand breaks as measured by the alkaline comet assay. The hypercondensed nuclei could be decondensed by irradiation with gamma-rays or exposure to light. The data provide evidence that EtBr at high concentrations resulted in hypercondensation of chromatin below control level. The comet assay confirmed that the increase in AVTD peaks deals with relaxation of loops and AVTD decrease is caused by chromatin condensation. The prediction of the AVTD theory for a correlation between time of radial migration and condensation of chromatin was verified. Further, the data show that the comet assay at neutral conditions of lysis is rather sensitive to DNA loop relaxation in the absence of DNA damage. Finally, donor specificity was found for the hypercondensation.

Adult↗

PubMed1999

A pre-steady-state kinetic analysis of substrate binding to human recombinant deoxycytidine kinase: a model for nucleoside kinase action.

Deoxycytidine kinase (dCK) is an enzyme with broad substrate specificity which can phosphorylate pyrimidine and purine deoxynucleosides, including important antiviral and cytostatic agents. In this study, stopped-flow experiments were used to monitor intrinsic fluorescence changes induced upon binding of various phosphate donors (ATP, UTP, and the nonhydrolyzable analogue AMP-PNP) and the acceptor dCyd to recombinant dCK. Monophasic kinetics were observed throughout. The nucleotides as well as dCyd bound to the enzyme by a two-step mechanism, involving a rapid initial equilibrium step, followed by a protein conformational change that is responsible for the fluorescence change. The bimolecular association rate constants for nucleotide binding [(4-10) x 10(3) M-1 s-1] were 2-3 orders of magnitude lower than those for dCyd binding [(1.3-1.5 x 10(6) M-1 s-1]. This difference most likely is due predominantly to the large difference in the forward rate constants of the conformational changes (0.04-0.26 s-1 vs 560-710 s-1). Whereas the kinetics of the binding of ATP, UTP, and AMP-PNP to dCK showed some differences, UTP exhibiting the tightest binding, no significant differences were observed for the binding of dCyd to dCK in the presence or absence of phosphate donors. However, the binding of dCyd to dCK in the presence of ATP or UTP was accompanied by a 1.5- or 3-fold higher quenching amplitude as compared with dCyd alone or in the presence of AMP-PNP. We conclude that ATP and UTP induce a conformational change in the enzyme, thereby enabling efficient phosphoryl transfer.

Adenosine Triphosphate↗

PubMed1999

[A high degree of accuracy is possible in the diagnosis of appendicitis. Laboratory tests, ultrasonography and computerized tomography are of great value].

Although acute appendicitis is often difficult to diagnose and negative laparotomy rates of 25 per cent are common, several options are currently available for the preoperative work-up. Careful history taking and physical examination are essential, together with analysis of inflammatory variables (C-reactive protein and white cell count). After admission, additional help is available in the form of ultrasonography and computerised tomography (CT), ultrasonography apparently being best in slender and normal weight patients (body mass indices < 25) and CT in overweight patients. The article reports how, without using invasive laparoscopy, a negative laparotomy rate of 7.2 per cent (11% in women and 4% in men) was obtained in 1998 at a hospital serving a population of 330,000.

Appendicitis↗

PubMed1999

Novel Salmonella typhimurium properties in host--parasite interactions.

Inflammatory bowel disease (IBD) comprises different diseases in the gastrointestinal tract in human, of which Crohn's disease (CD) and ulcerative colitis (UC) are the most prominent. A key factor in the etiology of IBD is the chronic inflammatory process, and a large body of evidence suggests that the transcription factor nuclear factor-kappa B (NF-kappaB) is the key regulator of responses determining the clinical inflammatory condition. Recent findings using antisense oligonucleotides provide direct evidence that the p65 subunit of NF-kappaB plays a central role in chronic intestinal inflammation. It has previously been shown that the Gram negative bacteria Yersinia pseudotubercolosis targets the eukaryotic signal transduction pathway(s) that lead to NF-kappaB activation (and thus avoid an anti-bacterial inflammatory response). In this paper, growth-based selected Salmonella typhimurium clones have been used to generate a clearer picture of the molecular mechanisms involved in host-parasite interactions. From the results presented here, S. typhimurium and Y. pseudotubercolosis may use the same mechanism to block NF-kappaB activation, following host cell infection. A new adaptational feature could also be shown, where a growth-based selected bacteria avoided the normally induced translocation of NF-kappaB in host cells.

Biological Transport↗

PubMed1999

Generation of a new protein purification matrix by loading ceramic hydroxyapatite with metal ions--demonstration with poly-histidine tagged green fluorescent protein.

The gene encoding the green fluorescent protein (GFP) from the jellyfish Aequorea victoria, was inserted under transcriptional control of the polyhedrin promoter of the Autographa californica nuclear polyhedrosis virus and expressed in the Spodoptera frugiperda insect cell line Sf9 during viral infection. The baculovirus transfervector pBlueBacHisB was used for constructing the recombinant baculovirus, so that the green fluorescent protein could be tagged with a poly-histidine tail. This fusion protein was utilized as a marker for evaluating the properties of metal ion loaded ceramic hydroxyapatite as a matrix in protein purification. Ceramic hydroxyapatite loaded with Zn(II) was the best choice for purifying this poly-histidine tagged GFP, followed by Fe(III) of the metal ions tested. Ni(II) that is superior especially in many poly-histidine purification systems did not, when loaded to hydroxyapatite, have binding properties comparable to Zn(II) or Fe(III). Elution of poly-histidine tagged GFP was best performed with phosphate buffers or EDTA that could compete with the phosphate molecules in hydroxyapatite or complexly bind the metal ions, respectively.

Animals↗

PubMed1999

Decreased resistance to gemcitabine (2',2'-difluorodeoxycitidine) of cytosine arabinoside-resistant myeloblastic murine and rat leukemia cell lines: role of altered activity and substrate specificity of deoxycytidine kinase.

We determined the potential activity of 2',2'-difluorodeoxycytidine (gemcitabine, dFdC) in 1-beta-D-arabinofuranosylcytidine (ara-C)-sensitive and-resistant leukemia cell lines. Both drugs are phosphorylated by deoxycytidine kinase (dCK); the triphosphates, dFdCTP and ara-CTP, respectively, are incorporated into DNA. In the murine leukemia cell line L1210, induction of resistance to ara-C resulted in the 2200-fold resistant subline L4A6. The Brown Norway rat myelocytic leukemia ara-C-sensitive cell line (BCLO) was >300-fold more sensitive to ara-C than its variant Bara-C. In L1210 cells, gemcitabine was 8-fold more active than ara-C; in L4A6, BCLO, and Bara-C cells, gemcitabine was 16-, 28-, and more than 3-fold more active than ara-C, respectively. A partial explanation for these differences may be the higher dCK activity in the parental cell lines L1210 and BCLO with gemcitabine compared to ara-C as a substrate. DCK activity was not or hardly detectable in the resistant L4A6 and Bara-C cell. In the rat leukemia cell lines, deoxycytidine (dCyd) phosphorylation activity showed an aberrant pattern, since the activity with dCyd was 1.5-fold higher in the Bara-C cell line compared with BCLO, possibly due to thymidine kinase 2. The wild-type L1210 cells accumulated at least 3-fold more ara-CTP and dFdCTP than the rat leukemia cell line BCLO. The ara-C-resistant variants L4A6 and Bara-C did not accumulate dFdCTP or ara-CTP. In conclusion, gemcitabine was more active than ara-C in all leukemia cell lines tested. The sensitivity of the wild-type cell lines correlates with the accumulation of dFdCTP and ara-CTP, but is independent of dCK. However, both resistant variants had decreased dCK activities, but were relatively more sensitive to dFdC than to ara-C.

Animals↗

PubMed1999

Human thymidine kinase 2: molecular cloning and characterisation of the enzyme activity with antiviral and cytostatic nucleoside substrates.

Based on amino acid sequence information from purified mitochondrial thymidine kinase (TK2), a cDNA of 1930 bp was cloned, containing an open reading frame encoding 232 amino acid residues starting with the N-terminal sequence determined from the native human protein preparation. Northern blot analysis with the cDNA coding region demonstrated several TK2 mRNAs, with 2 and 4 kb forms present in many tissues. We also characterised N-terminally truncated (starting at position 18) human TK2 with pharmacologically important antiviral and cytostatic nucleoside analogues. Results were highly similar to those with the native TK2 preparation. The anti-leukaemic drug arabinosyl cytosine is phosphorylated. The antitumour drug difluorodeoxycytidine and its metabolite difluorodeoxyuridine are good substrates, with K(m) values of 66 and 29 microM, respectively, and a relative Vmax of 0.6 compared to that of thymidine. Negative cooperativity was found with thymidine and the anti-HIV drug 3'-azidothymidine, but the reaction followed Michaelis-Menten kinetics with deoxycytidine, arabinosyl cytosine, and arabinosyl thymine. The results demonstrate a broad substrate specificity and complex kinetics, and suggest a role for TK2 in the activation of chemotherapeutic nucleoside analogues.

Amino Acid Sequence↗

PubMed1999

Low enantioselectivities of human deoxycytidine kinase and human deoxyguanosine kinase with respect to 2'-deoxyadenosine, 2'-deoxyguanosine and their analogs.

The antiviral activity of L-nucleoside analogs depends in part on the enantioselectivity of nucleoside kinases which catalyse their monophosphorylation. The substrate properties of human recombinant deoxycytidine kinase (dCK) and human recombinant deoxyguanosine kinase (dGK) with respect to L-adenosine and L-guanosine analogs, in the presence of saturating amounts of ATP and relatively high concentrations of substrates, demonstrated a marked lack of enantioselectivity of both these enzymes. Human dCK catalysed the phosphorylation of D- and L-enantiomers of beta-dA, beta-araA, and beta-dG with enantioselectivities favoring the unnatural enantiomer for the adenosine derivatives and the natural enantiomer for 2'-deoxyguanosine. No other tested L-adenosine or L-guanosine analog was a substrate of dCK. Similarly, D- and L-enantiomers of beta-dA, beta-araA, and beta-dG were substrates of human dGK but with different enantioselectivities compared to dCK, especially concerning beta-dA. The present results indicate that human dCK and dGK have similar properties including substrate properties, relaxed enantioselectivities, and possibly catalytic cycles.

Deoxyadenosines↗

PubMed1999

Treatment of normal and malignant cells with nucleoside analogues and etoposide enhances deoxycytidine kinase activity.

Deoxycytidine kinase (dCK), one of the rate-limiting enzymes in the intracellular metabolism of many antileukaemic drugs, was shown to be stimulated after treatment of human tonsillar lymphocytes by 2-chloro-2'-deoxyadenosine (cladribine, CdA) (Sasvári-Székely, et al., Biochem Pharmacol 1998, 56, 1175-1179). Here we present a comparative study of different normal and malignant cells in respect to the activation of dCK by CdA. G-phase lymphocytes showed a higher sensitivity for dCK stimulation than S-phase cells. Normal and leukaemic peripheral blood mononuclear cells, as well as the promyelocytic cell line HL60 responded to CdA treatment by a 2-5-fold increase in activity of dCK. However, no significant stimulation was detected either in CCRF-CEM T-lymphoblastoid cells, or in K562 myeloid cells. Thymidine kinase (TK) activity was not stimulated in any cases. Treatment of these cells with several other analogues beside CdA, such as 2-chloro-2'-arabino-fluoro-2'-deoxyadenosine (CAFdA), 2-fluoro-1-beta-D-arabinosyladenine (Fludarabine, FaraA) and 1-beta-D-arabinosylcytosine (cytarabine, araC) gave similar results to CdA treatment. Enhancement of dCK activity could also be achieved with the topoisomerase II inhibitor, etoposide. In contrast, 2-chloro-riboadenosine (CrA) had no effect on the dCK at concentrations of 10 microM or less, while dCyd and 5-aza-dCyd caused slight inhibition. These results indicate that treatment of cells with several inhibitors of DNA synthesis potentiates the dCK activity. The drugs widely differ in their stimulatory effect on dCK, and there are also 'responsive' and 'non-responsive' cells with respect to dCK activation. Thus, enhancement of the dCK activity by specific drugs in 'responsive' cells might give a rationale for combination chemotherapy.

Antineoplastic Agents, Phytogenic↗

PubMed1999

Extrahepatic manifestations of chronic hepatitis C infection and the interrelationship between primary Sjögren's syndrome and hepatitis C in Swedish patients.

OBJECTIVE: To analyse the frequency of some extrahepatic manifestations of chronic hepatitis C virus (HCV) infection in northern European patients, including a postulated association between HCV and primary Sjögren's syndrome (SS). DESIGN: Cohort study. SETTING: Department of Medicine, Malmö University Hospital, Sweden. PATIENTS: Twenty-one patients with HCV infection and 53 with primary SS (according to the Copenhagen criteria). MAIN OUTCOME MEASURES: Cryoglobulins were analysed in all patients, while patients with primary SS were investigated with regard to markers of HCV infection, and HCV patients with objective tests of SS (Schirmer-1 test, break-up time, van Bijsterveld score, sialometry, labial salivary gland biopsy) and antibodies against nuclear antigens, smooth muscle (SMA) and mitochondria (AMA). HCV antigens in small salivary glands from lower lip biopsies were detected by immunohistochemical analysis. RESULTS: Only one of the SS patients had detectable cryoprecipitates, while another was HCV-positive. None of the 21 HCV patients had cryoprecipitates. A total of 14/21 (67%) patients with HCV infection had at least one abnormal objective test suggestive of xerostomia or keratoconjunctivitis sicca, while eight (38%) had objective evidence of both eye and salivary gland involvement. HCV antigens were not detected in affected glands. Only two patients had clinical symptoms of SS, and two fulfilled the Copenhagen criteria for SS. None of the HCV-positive patients had detectable antibodies against SS-A, SS-B, RNP, Jo-1, PCNA or Scl-70, and the frequency of ANA/SMA/AMA was low. CONCLUSIONS: While involvement of salivary and lacrimal glands was common in Swedish patients with HCV infection, cryoglobulinaemia was not observed. The pathogenetic mechanism responsible for glandular inflammation appears to be different from that in primary SS. HCV infection does not seem to be an aetiological factor for primary SS in this population. These observations suggest that viral, genetic or possibly environmental factors may be responsible for the reported high frequencies of systemic complications associated with chronic hepatitis C infection in southern Europe.

Adult↗

PubMed1999

Is there a relationship between abdominal aortic aneurysms and alpha1-antitrypsin deficiency (PiZ)?

OBJECTIVE: To determine if the frequency of alpha 1AT deficiency (PiZ) is increased in patients with abdominal aortic aneurysm (AAA), and, to investigate whether aneurysmal stiffness and other clinical characteristics differ in AAA patients with and without alpha 1AT deficiency. METHODS: We identified alpha 1AT-deficient individuals by a monoclonal-antibody ELISA technique, in 102 consecutive patients with AAA. Positive ELISA samples were further phenotyped by isoelectric focusing to differentiate between the heterozygosity (PiZ) and homozygosity (PiZZ) state. Aneurysmal diameter and stiffness was measured using echotracking sonography and blood pressure measurements. RESULTS: The frequency of heterozygous alpha 1AT deficiency (PiZ) in patients with AAA was similar to that in the general population (6.8% and 4.7%, respectively, p > 0.3). The frequency of popliteal and femoral aneurysm was similar in male PiZ-carriers and non-carriers with AAA, as were age at diagnosis of AAA, aneurysmal diameter, aneurysmal stiffness, and presence of factors that may be associated with AAA (i.e. smoking, hypertension, diabetes mellitus, and family history of AAA). Occurrence of ischaemic heart disease was more frequent in male non-PiZ-carriers than in male PiZ-carriers with AAA (p = 0.03). CONCLUSIONS: The frequency of alpha 1AT deficiency (PiZ) was not increased in our series of patients with AAA and patients in whom the two disorders coexisted did not appear to have different clinical characteristics except for the lower occurrence of ischaemic heart disease among the PiZ-carriers.

Aged↗