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Biomedical subjects

W Mertens

Publications and source records attributed to W Mertens.

At least 19 recordsLinked to original sources
PubMed2006

Use of a (proposed) standard protocol to validate Terumo TSCD-II connections between dissimilar blood bag tubing.

BACKGROUND AND OBJECTIVES: ISO standards for blood bags do not adequately define and control the dimensions of blood bag transfer tubing. This lack of standardization presents potential difficulties when making sterile connections between the wide range of tubing that has evolved in the absence of such standards. We aim to validate the suitability of the TSCD-II and provide a minimum standard for assessing the suitability of sterile connections (welds) between dissimilar tubing. MATERIALS AND METHODS: The Terumo TSCD-II was used in this study to connect by hermetic welding seven tubing types with a wide range of dimensions from five suppliers. Thirty sterile connections were made between each combination split between dry/dry, wet/wet and dry/wet connections. Welds were assessed for visual defects, by tensile stress test (TST) and pressure tests. RESULTS: All welds passed visual inspection and pressure tests. All welds had a minimum tensile strength of greater than 40 N and mean of greater than 45 N. CONCLUSION: Successful connections have been made between dissimilar tube types and this work does not support the requirement for 'tight' tubing dimensional specifications. We have recommended to the ISO Technical Committee 76 Work Group 1 that ISO 3826-1 be revised and should include a minimum standard validation protocol for joining dissimilar tubing.

Blood Component Transfusion↗
PubMed2001

Neoadjuvant estramustine and etoposide followed by concurrent estramustine and definitive radiotherapy for locally advanced prostate cancer: feasibility and preliminary results.

PURPOSE: Current therapy for locally advanced prostate cancer is suboptimal. A treatment regimen was designed to improve systemic control by neoadjuvant targeting of hormone-sensitive and -insensitive micrometastatic disease and to improve local control by escalating the biologic effective dose to the prostate using estramustine (EMP) concurrently with radiotherapy. PATIENTS AND METHODS: Eighteen patients with locally advanced prostate cancer (Stages T3/T4 or T1c/T2b/T2c with a Gleason score of > or =7 and a serum PSA >15 ng/ml) were entered onto this trial. Therapy consisted of two 21-day cycles of oral estramustine (10 mg/kg/day) in three divided doses and oral etoposide (50 mg/m(2)/day, in two divided doses), followed by concurrent estramustine (10 mg/kg/day, PO) and three-dimensional conformal radiotherapy. RESULTS: Two patients required discontinuation of chemotherapy due to development of Grade 3 and 4 toxicity. All others completed both components of therapy per protocol guidelines. Minor toxicities included alopecia (100% of patients), anemia (69%), leukopenia (37%), thrombocytopenia (19%), and nausea (6%) but did not require dose modifications. There were no fatalities. Actuarial 3-year overall survival and disease-free survival (DFS) were 88% and 73%, respectively. Local control rate, assessed by repeated prostate biopsies at 18 months post completion of therapy, was 71%. CONCLUSION: The described regimen is well tolerated, and preliminary efficacy data are encouraging. The underlying concepts of early targeting of both hormone-sensitive and -insensitive micrometastatic clones, in combination with aggressive local therapy, warrant further investigation.

Aged↗
PubMed1998

Binding of the Co(NH3)4 derivative of (2')3'-O-[N-methyl-anthraniloyl]-ATP to the E2ATP site of Na+/K+-transporting ATPase lowers the conformational flexibility of its E1ATP site.

Na+/K+-activated ATP hydrolysis by the sodium pump is catalyzed by the interaction of high-affinity and low-affinity ATP-binding sites [Thoenges, D. & Schoner, W. (1997) J. Biol. Chem. 272, 16315-16321]. To explore how binding of ATP to the low-affinity E2ATP site affects the conformational flexibility of the high-affinity E1ATP site due to interaction with Na+ or K+ ions, the E2ATP site was blocked with a fluorescent MgATP complex analog and fluorescence changes of the E1ATP site modified by FITC (fluorescein 5'-isothiocyanate) were studied. The fluorescent MgATP complex analog Co(NH3)4MANT-ATP [beta,gamma-bidentate complex of 2'(3')-O-(N-methylanthraniloyl)-ATP] inactivated Na+/K+-ATPase in a time-dependent and concentration-dependent process with a Kd of 0.17 mM and an inactivation rate constant, k, of 0.031 min(-1). ATP protected against the inactivation with a Kd of 0.43 mM. Consistent with a modification of the E2ATP binding site, Co(NH3)4MANT-ATP inactivated the K+-activated phosphatase activity in an enzyme whose E1ATP site had already been modified by FITC. Inactivation by Co(NH3)4MANT-ATP was due to tight binding which resulted in a loss of fluorescence. Tightly bound Co(NH3)4MANT-ATP could only be released by denaturation with SDS. Analysis of the conformational flexibility of the E1ATP site after labeling with FITC led to a K+-dependent quench of fluorescence which is reversed by Na+. This flexibility was lost upon the blockade of the E2ATP site by Co(NH3)4MANT-ATP.

Adenosine Triphosphate↗
PubMed1998

Costsaving in the operating room: the Procedure Pack.

The concept of the Procedure Pack is very relevant in this era of managed care. By collecting more items in one pack, the hidden costs will be reduced and the pack will become relatively cheaper than the sum of every item. This paper compares the price of the Procedure Pack with the price of the separate items used for routine phaco-emulsification. The Procedure Pack is 2% more expensive, but the benefits by reducing the hidden costs are substantial and will be analyzed.

Belgium↗
PubMed1995

Localization and reactivity of an immunodominant domain in the NS3 region of hepatitis C virus.

Analysis of the amino acid sequences of the nonstructural region 3 (NS3) of the hepatitis C virus type 1 revealed four points with a high average hydrophilicity (Ah). Two of these potential antigenic sites were expressed in E. coli as short fragments. The first fragment of 91 residues (NS3f3: residues 1359-1449) harbors the hexapeptide K-K-K-C-D-E with an Ah of 2.33; the second fragment is 73 residues long (NS3f4: residues 1460-1532) and encompasses the heptapeptide R-S-N-R-R-G-R with an Ah of 1.79. Both fragments were expressed with truncated hepatitis B core (tHBc) as a carrier protein. The fusion proteins were purified from the bacterial lysates by affinity chromatography on immobilized monoclonal antibodies against HBc, and evaluated as antigens in an enzyme immunoassay for the detection of HCV antibodies. In a specificity control panel, reactivity with NS3f3 was only found in proven HCV carriers, while reactivity with NS3f4 was weak in HCV carriers but accounted for some of the nonspecific serological reactions. In a group of 48 genotyped HCV-infected volunteer blood donors, antibodies against NS3f3 were detected in 90% (27/30) of HCV-type 1 infections and in all HCV-type 4 infections (5/5).(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1995

Prognostic significance of cellular proliferation in renal cell carcinoma: a comparison of synthesis-phase fraction and proliferating cell nuclear antigen index.

DNA aneuploidy has repeatedly been shown to be a significant prognostic indicator in renal cell carcinoma; however, few studies have emphasized the importance of measurements of cellular proliferation. This study evaluated 55 patients treated by radical nephrectomy and for whom clinical follow-up was available. There were 36 men and 19 women with a mean age of 61 yr. Robson stage distribution was I, 38 cases; II, five cases; and III, 12 cases. Flow cytometric analysis in 44 cases revealed 29 DNA diploid and 15 DNA aneuploid tumors with a median synthesis-phase fraction (SPF) of 4.4% (range 1.0 to 31.4%). The median proliferating cell nuclear antigen index was 3.9% (range 0.1 to 58.0%). There was a significant correlation between SPF and proliferating cell nuclear antigen index (R = 0.769) in the 33 cases in which both were available. Cellular proliferation, as determined by SPF, was a significant prognostic indicator (P < 0.02), but proliferating cell nuclear antigen index did not correlate with outcome (P > 0.05). Other significant predictors in this study were Robson stage (P = 0.03) and nuclear grade (P = 0.0003). DNA ploidy did not correlate with outcome (P > 0.05). We conclude that cellular proliferation, as measured by SPF analysis, is a significant predictor of outcome for renal cell carcinoma. Although the proliferating cell nuclear antigen index correlated with SPF, it did not achieve statistical significance as a prognostic indicator.

Adult↗
PubMed1995

[Why (some) psychoanalytic therapies (must) have a long duration. Thoughts on appropriate catamnestic methods].

First the author discusses some of the reasons why psychoanalytic therapy takes time, showing in the process how the psychoanalytic understanding of time is at odds with the everyday concept of it. He then makes out a case against the unthinking adoption of the psychometric procedures and evaluation techniques used hitherto in determining the success of psychotherapy. In this way certain erroneous developments in traditional psychology can be avoided in psychoanalytic catamnesis. In the concluding section the author outlines an alternative methodology of catamnesis geared to the specific epistemological requirements inherent in the process of psychoanalysis.

Follow-Up Studies↗
PubMed1994

Evaluation of third-generation screening and confirmatory assays for HCV antibodies.

A third-generation (gen.) screening and immunoblot assay (Ortho EIA-3.0; Chiron RIBA-3 prototype), using antigens derived from the capsid and different nonstructural regions (NS3, NS4 and NS5) of the hepatitis C virus viral genome, were evaluated in comparison with the corresponding second-gen. assays (Ortho EIA-2.0; revised Ortho EIA-2.5; Chiron RIBA-2). In 203 depository sera of blood donors, positive in EIA-2.0, specificity of the screening assays was improved as shown by an increase in positive predictive value for viral carrier state from 0.23 (EIA-2.0) to 0.37 (EIA-2.5) and 0.52 (EIA-3.0). Comparing the confirmation patterns on RIBA-2 and RIBA-3, this amelioration was mainly due to the specific elimination of false-positive c22-3 and c100-3 reactions. Antibody response to the newly added NS5 antigen was not as prevalent as to the other antigens and had only a minor influence in sample allocation. In contrast, screening of 1,560 volunteer blood donors and 47 hemodialysis patients revealed 3 additional positive sera, only reacting with the NS5 antigen. However none of these isolated NS5 reactions could be confirmed on synthetic peptides [INNO-LIA: NS5(p)] and none was PCR positive. A documented seroconversion, detected earlier with EIA-3.0, was related to a better immunological response to the NS3 antigen and not to the additional NS5. From this pilot study third-gen. assays appeared extremely useful in the reevaluation of HCV-seropositive depository sera. However the additional value of the NS5 antigen in blood donor screening is still hypothetical and remains to be established in larger screening studies.

Antigens, Viral↗
PubMed1994

[Psychoanalysis on trial? On the empirically disguised professional politics of Klaus Grawe].

In the introduction the question is answered, why the meta-analysis of Klaus Grawe, Ruth Donati und Friederike Bernauer should be taken seriously by psychoanalysts. Above all is a problem, that implicit in this meta-analytical evaluation there are methods and criterions of the empirical behavioristic psychotherapy research, which favour automatically the behavioral therapy. The abuse of empirical research to denigrate psychoanalytic training and training institutes is criticized. Reflection on adequate assumptions for a psychoanalytical psychotherapy research is pleaded for and some requirements are mentioned. In view of the mentioned deficiencies the claim of Grawe et al. to deduce important conclusions on their meta-analysis, must be evaluated as false.

Behavior Therapy↗
PubMed1993

The mitochondrial tricarboxylate carrier.

The tricarboxylate carrier has recently been purified from rat liver mitochondria by three distinct scientific groups using different methods. A 37-38-kDa protein has been prepared by silca gel 60 chromatography by our group (Claeys and Azzi, 1989; Glerum et al., 1990). The specific citrate transport activity of this preparation is not significantly different from that measured in mitochondria and it is inhibitable by 1,2,3-benzenetricarboxylic acid. Bisaccia et al. (1990) have reported the isolation of a 30-kDa protein by Celite 535 chromatography, and Kaplan's group (Kaplan et al., 1990) have isolated a 32.5-kDa protein by Matrex Orange, Matrex Blue, and Affi-Gel chromatography. Peptide mapping has failed to support any structural homologies between the 37-38-kDa and the 30-32.5-kD proteins. The 38-kD protein is N-terminally blocked. The peptides obtained by several cleavage procedures have been partially sequenced. Their sequence information has been used to obtain different cDNA clones by a dual approach, the polymerase chain reaction and screening of a lambda ZAP cDNA library. The largest cDNA which could be isolated is 2,986 bp in length and contains a 1071-bp-long open reading frame and an unusually long 3' untranslated region, both of which have been completely sequenced. The protein sequence of the carrier from the first in-frame methionine is 322 amino acids in length and exhibits a molecular mass of 35,546. Comparison of the protein sequence to the sequences of the four members of the mitochondrial carrier protein family (ADP/ATP carrier, phosphate carrier, 2-oxoglutarate/malate carrier, and uncoupling protein) does not reveal significant similarity (cf. Walker et al., 1987). A tripartite internal homology, which is a characteristic of these proteins, is not present in the sequence of the tricarboxylate carrier protein. The mRNA for the tricarboxylate carrier is expressed in rat liver and brain, but not in rat heart.

Amino Acid Sequence↗
PubMed1993

Hepatitis C virus confirmation in blood donor screening.

A combination of different enzyme immunoassays (EIAs) was used for the serological confirmation of sera that were positive in a hepatitis C virus (HCV) second-generation screening EIA. Different reaction patterns were related with the probability of the HCV-carrier state as determined by polymerase chain reaction (PCR). Five hundred and eight sera of volunteer blood donors were send for confirmation and at first reexamined with both Abbott and Ortho second-generation screening EIA. A group of 195 sera, positive in both assays, was further evaluated by the Abbott Supplemental Assay, the Monolisa anti-HCV and an EIA with only the amino terminal part of the nucleocapsid protein as antigen. In addition PCR on the 5'-noncoding region of the viral genome was performed. We observed that 75 of the 78 PCR-positive sera were found in a group of 89 sera that were strongly positive in the four EIAs used. Moreover all but 1 PCR-positive sera were reactive against the nucleocapsid protein of the virus. Hence we concluded that a genuine antibody response to the nucleocapsid protein is highly suggestive for the HCV-carrier state.

Blood Donors↗
PubMed1992

Synthesis and biochemical characterization of the new sulfhydryl-reactive ATP analogue 8-thiocyano-ATP. Its interaction with Na,K-ATPase and kinases.

The synthesis of 8-thiocyano-ATP (CNS8-ATP) is described. At 37 degrees C the ATP analogue inactivates Na,K-ATPase, hexokinase, and pyruvate kinase. In all three cases, inactivation can be prevented by the addition of ATP, thus indicating that CNS8-ATP is recognized within the ATP binding site of the above enzymes. Incubation of the inactivated enzymes with dithiothreitol restores the catalytic activities. Therefore, it is likely that in these enzymes a mixed disulfide (E-S-S8-ATP) is formed between a sulfhydryl in the ATP binding site (E-SH) and the ATP analogue: [formula: see text] From the pseudo-first-order inactivation kinetics, a KD = 2.7 microM with k2 = 0.142 min-1 is calculated for the hexokinase and a KD = 40 microM with k2 = 0.347 min-1 is calculated for the pyruvate kinase interactions with the ATP analogue. At 4 degrees C, Na,K-ATPase recognizes CNS8-ATP with a KD = 8.3 microM. At 37 degrees C, the enzyme becomes inactivated by the ATP analogue in a biphasic manner. Inactivation results in the incorporation of [alpha-32P]8-CNS8-ATP into the catalytic alpha-subunit of the enzyme. Limited tryptic digestion in the presence of 150 mM KCl results in the formation of a radioactive peptide of Mr = 56,000, known to bear the purine binding domain of Na,K-ATPase. The results described in this article verify CNS8-ATP as a sulfhydryl-reactive ATP analogue and characterize this new ATP analogue as a useful tool for structure/function studies on ATP-recognizing enzymes.

Adenosine Triphosphate↗
PubMed1991

Azido derivative of tricarboxylic acid for photoaffinity labeling.

A new photoaffinity probe, 5-(1-hydroxy-4-azidophenylazo)-1,2,3-benzenetricarboxylic acid, was synthesized and characterized. This reagent can be potentially used in photoaffinity labeling of the mitochondrial tricarboxylate carrier, as well as of enzymes interacting with tricarboxylic acids. Inhibition and labeling of the mitochondrial tricarboxylate carrier is presented.

Affinity Labels↗
PubMed1990

The tricarboxylate carrier from rat liver mitochondria. Purification, reconstitution and kinetic characterization.

The tricarboxylate carrier from rat liver mitochondria has been purified and reconstituted into phospholipid vesicles. Its activity has been characterized by both a radioactive citrate uptake assay and a coupled enzymatic assay. A Km of 40 microM and a Vmax of 1.56 mumol x min-1 x mg-1 have been determined for the carrier. Cholesterol levels of between 5-10% of total lipid content are shown to cause a decrease in carrier activity.

Animals↗