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Y Schmitt

Publications and source records attributed to Y Schmitt.

15 recordsLinked to original sources
PubMed2004

Evaluation of sensitivity for wild type and mutant forms of hepatitis B surface antigen by four commercial HBsAg assays.

Hepatitis B surface antigen is one of the most important serological markers used to diagnose an HBV infection. Improvements in HBsAg assay sensitivity have been achieved constantly over the years since introduction of the first commercial assays. It is generally assumed that diagnostic assay sensitivity includes the ability to detect wild type and viral variants at the same level. Thus it would be expected, as newer HBsAg assays are developed, that viral mutation would be considered in assay design and that assay sensitivity would be equivalent for wild type as well as mutant forms. Two newly launched HBsAg assays (Bayer ADVIA Centaur and Ortho VITROS ECi) were compared to two established HBsAg assays (Abbott AxSYM and Roche Elecsys) in order to test the assumption that assay sensitivity for variants is equivalent to wild type HBsAg. The four assays were challenged with a standard HBsAg sensitivity panel of both ad and ay subtypes as well as a 13 member mutant panel comprised of both recombinant and native HBsAg members. Results demonstrate that the analytical sensitivity for wild type HBsAg is comparable for all assays tested. In contrast, significant differences were observed for detection of mutants. AxSYM HBsAg detected all mutant samples while all other asssays missed 10 out of 13 samples tested. It is noteworthy that the most frequently reported HBsAg mutation, G145 R, remained undetected in three of the assays tested. It is discussed whether the reduced sensitivity for mutants of the most recent assays represents a new risk for the diagnosis of HBV infection.

DNA, Viral↗
PubMed2001

Performance characteristics of quantification assays for human immunodeficiency virus type 1 RNA.

Quantification of human immunodeficiency virus type 1 (HIV-1) is useful in obtaining information about the prognosis of patients and monitoring of antiviral therapy. Today, commercial assays based on reverse transcription-polymerase chain reaction (RT-PCR), the branched DNA (bDNA) technology and on nucleic acid sequence-based amplification (NASBA) are available. Clinical relevance of those assays is limited because of relatively poor reproducibility, especially for low copy numbers and unequal amplification dynamics for different genotypes. Better standardisation is most important in order to improve the reliability of quantitative molecular assays.

HIV Infections↗
PubMed2000

Screening for abnormalities of the protein C anticoagulant pathway using the ProC Global assay. Results of a European multicenter evaluation.

ProC Global is a new global clotting assay designed to evaluate the functionality of the protein C anticoagulant pathway. It is based on the ability of endogenous activated protein C, generated by activation of protein C by Protac, to prolong an activated partial thromboplastin time, and the results are expressed in protein C activation time normalized ratio (PCAT-NR), after normalization. This multicenter trial involving five European laboratories was designed in order to determine the ability of the ProC Global assay to distinguish patients with and without abnormalities of the protein C pathway. The PCAT-NR was significantly lower in the patients with a thrombotic history not on oral anticoagulant treatment (n = 627) than in the healthy controls (n = 148), even after exclusion from both groups of the patients with abnormality of the protein C pathway. Using receiver operator characteristics analysis, the cut-off level of PCAT-NR = 0.80 was found to provide the best sensitivity-specificity ratio. All the carriers of the factor V Leiden mutation (n = 73), as well as all the patients with activated protein C resistance (n = 42), had a PCAT-NR below 0.80. The ProC Global assay performed well in patients with combined defects (97.0%, n = 33) or protein C deficiency (91.3%, n = 46), but it failed to detect all of them, and one patient with combined defects as well as four patients with a low protein C level had a PCAT-NR above the cut-off level. The sensitivity of the assay for protein S deficiency (n = 58) was weak (only 69.0%) and, surprisingly, more than 40% of the 375 patients without any of these abnormalities of the protein C pathway had a PCAT-NR below the cut-off level.

Activated Protein C Resistance↗
PubMed1997

Copper and zinc determination in plasma and corpuscular components of peripheral blood of patients with preterminal and terminal renal failure.

Homeostasis of trace elements is an essential condition for the activation and regulation of metabolic processes. Its disturbance results in clinical symptoms. Since most trace elements are eliminated via the renal system, their balance is disturbed in patients with preterminal or terminal renal insufficiency. However, only a low percentage of trace elements can be detected in plasma, so that the intracellular determination of trace elements in corpuscular components in peripheral blood cells might be of interest. After blood was taken from the shunt vessel, the cells were isolated by density gradient centrifugation media. The concentrations of the trace elements copper and zinc in peripheral blood cells and plasma were determined by means of electrothermal atomic absorption spectrometry. Compared with healthy blood donors, in patients with preterminal and terminal renal insufficiency concentrations in plasma and peripheral blood cells were altered but in different directions. In renal insufficiency copper concentration in plasma (median: 13.9 mumol/l) and erythrocytes (median: 0.8 mumol/ 10(9) cells) was normal and in the lower reference range, respectively, whereas copper concentration in the platelets was elevated (median of 20 mumol/1 10(9) cells). As regards zinc, patients with preterminal and terminal renal insufficiency both suffered from low values in plasma (median: 8.6 mumol/l). In contrast, the concentration in erythrocytes and thrombocytes was elevated (medians: 17.9 mumol/10(9) cells and 14.0 mumol/10(9) cells, respectively)). In conclusion, the intracellular determination of the trace elements copper and zinc is of value for diagnosis and monitoring of the trace element deficiency status.

Blood Cells↗
PubMed1996

[Mechanical autotransfusion also in transurethral resection of prostatic adenoma? Studies of preserved washed erythrocyte concentrates before possible retransfusion].

AIM: Does cell-saving during transurethral resection of prostatic adenoma (TURP) provide autologous washed erythrocyte concentrates (AWECs) of the same haematological and bacteriological quality as that of established indications of a cell-saving device? Should the cell-saving device be used routinely in TURP? METHODS: 37 patients underwent TURP with written, informed consent. All patients had antibiotic therapy prior to surgery. Shed blood was processed by a cell-saving device. AWECs specimens were analysed for red blood count, electrolytes, LDH, extracellular haemoglobin, osmotic fragility, blood culture and bacterial concentration. In addition, data of urine cultures, adenoma cultures and adenoma histology were analysed. AWEcs were not retransfused. RESULTS: Haematological quality was shown to be comparable to that of established applications of a cell-saving device. However, 82% of the AWECs were contaminated with bacteria. Concentrations were as high as > 10(6) bacteria/ml. Isolated bacteria ranged from e. coli and pseudomonas to staphylococci, streptococci and candidae. Bacteria found in the urine cultures of patients with urinary tract infections could also be isolated in their AWECs. 16% of the patients had prostatic cancer not know preoperatively. Mass of resected adenoma and volume of AWEC did not correlate. CONCLUSIONS: In despite of good haematological quality we considered the rate of 82% bacterial and 16% tumour cell contamination of the AWECs unacceptable and, contrary to some literature data, we no longer use a cell-saving device in TURP.

Aged↗
PubMed1993

[The effect of highly unsaturated fatty acids on the parameters of lipoprotein metabolism and rheology during their administration to patients undergoing chronic hemodialysis treatment].

Fifteen hemodialysis patients were treated with capsules of highly unsaturated fatty acids given in addition to their normal diet over a period of 6 months. At study start they received 12 capsules daily, each containing 105 mg eicosapentaenoic acid and 75 mg docosahexaenoic acid. There was a significant fall of triglycerides from an initial 521 mg/dl on average to 334 mg/dl. Total cholesterol was reduced from 266 mg/dl to 233 mg/dl with a continuous fall throughout the study period, ldl cholesterol being the main part, falling from 227 mg/dl to 192 mg/dl. These changes were accompanied by a reduction of apolipoprotein A1 from 118 mg/dl to 109 mg/dl and of B from 212 mg/dl to 204 mg/dl. Parameters of whole blood viscosity decreased significantly (viscous component eta' from 6.81 to 6.44 mPas--elastic component eta" from 1.85 to 1.53 mPas), while the plasma viscosity remained unchanged with 1.44 mPas. The improvement of flow properties results from adherence of omega-3 fatty acids to the phospholipids of the red cell membrane. The conclusion is that supplementation with fish oil in addition to normal food intake of dialysis patients contributes to an improvement of lipoprotein metabolism and flow properties. Thus, two risk factors concerning thrombosis and cardiovascular diseases can be positively influenced.

Aged↗
PubMed1993

Determination of the trace elements zinc, copper, nickel and chromium in bone marrow and plasma of patients with non-Hodgkin lymphomas.

The concentrations of zinc, copper, nickel and chromium were determined in bone marrow and plasma of 37 patients suffering from non-Hodgkin-lymphomas (NHL). The results were compared with a control group of 10 patients with negative histopathologic results in bone marrow. The results demonstrate that all patients with low grade and high grade NHL have elevated trace element levels in bone marrow compared to the control group. In plasma there are also differences in the trace element levels of patients with NHL compared to the control group; the levels, however, are partly higher and lower than those of the control group. Altogether the plasma level differences are not as noticeable as those in the bone marrow. At the moment it is not yet possible to draw final conclusions from these results for the prognosis or therapy of NHL, but the study tends to show that intracellular measurement of trace elements is more reliable than intraplasmic measurement.

Aged↗
PubMed1993

Low-molecular-weight heparin (LMWH): influence on blood lipids in patients on chronic haemodialysis.

A low-molecular-weight heparin (LMWH) has been compared to conventional heparin in haemodialysis in a 12-month study. In a group of 22 patients who had been on chronic haemodialysis for longer than 12 months, the conventional, unfractionated heparin was replaced by a low-molecular-weight analogue (LMWH) (Fragmin, Kabi-Pharmacia Erlangen) for 6 months. Baseline values of lipoprotein profile prior to the intervention were compared with results obtained after 2, 4 and 6 months of LMWH. Control values were obtained 3 and 6 months after switching back to conventional heparin. During the LMWH treatment total cholesterol decreased significantly. This coincided with a significant decrease in LDL cholesterol and a minor decrease in total HDL cholesterol. There was no noticeable change in the HDL cholesterol subfractions. The decrease of LDL and HDL was accompanied by a distinct and continuous decrease of apolipoprotein B throughout the LMWH period while the apolipoprotein A1 declined during the first 2 months and then stabilized at this lower value. Triglycerides increased significantly during the first 2 months and then rebounded to the initial values by the end of the LMWH treatment period. After switching back again to conventional heparin the lipoprotein parameters returned to the starting values. We conclude that the long-term use of low-molecular-weight heparin instead of conventional heparin for anticoagulation during dialysis may contribute to a reduction of the cardiovascular risk factors of haemodialysis patients.

Adult↗
PubMed1992

Chromatographic separation of serum proteins and estimation of their zinc and copper content.

Human serum proteins of blood donors and dialysis patients were separated by means of gel filtration chromatography. The resulting fractions were analyzed for copper and zinc. Separation resulted in 3 zinc peaks with a molecular weight of about 700,000, 300,000, and 75,000 Dalton, with alpha 2-macroglobulin co-eluting in the first and albumin co-eluting in the third zinc peak. The zinc protein(s) of the second peak remained unidentified. The three peaks contained, in succession, 0.72 +/- 0.30 mumol/L (4.8 +/- 1.6%), 1.26 +/- 0.37 mumol/L (8.5 +/- 1.7/1000) and 12.8 +/- 2.1 mumol/L (86.8 +/- 2.8%) of total zinc in the case of blood donors, and 1.19 +/- 1.05 mumol/L (9.2 +/- 7.2%), 0.97 +/- 0.22 mumol/L (8.0 +/- 2.6%), and 10.4 +/- 1.66 mumol/L (82.7 +/- 6.7%) in the case of dialysis patients. Separation followed by copper analysis resulted in the three peaks, as well, with a molecular weight of about 750,000, 140,000, and 75,000 dalton. The copper protein of the first peak remained unidentified, while coeruloplasmin co-eluted in the second and albumin in the third peak. The three peaks contained, in succession, 0.4 +/- 0.16 mumol/L (2.3 +/- 0.95%), 14.6 +/- 0.7 mumol/L (83.9 +/- 4.1%), and 2.4 +/- 0.6 mumol/L (13.7 +/- 3.5%) of total copper in the case of blood donors, and 0.5 +/- 0.73 mumol/L (2.2 +/- 3.2%), 19.5 +/- 1.1 mumol/L (90.5 +/- 4.9%), and 1.6 +/- 0.66 mumol/L (7.3 +/- 3.0/1000) in the case of dialysis patients. Limitation of the method is shown regarding separation of major from minor proteins and albumin from transferrin.

Blood Donors↗
PubMed1991

[Effect of the administration of highly-unsaturated fatty acids on the parameters of lipoprotein metabolism and rheology of patients under chronic hemodialysis treatment].

15 hemodialysis patients with hypertriglyceridemia were treated with capsules of highly unsaturated fatty acids given in addition to their normal diet over a period of 6 months. At study start they received 12 capsules daily, each containing 105 mg eicosapentaenoic acid and 75 mg docosahexaenoic acid. There was a significant fall in triglycerides from an initial 521 mg/dl on average to 334 mg/dl. Total cholesterol was reduced from 266 mg/dl to 233 mg/dl with a continuous fall throughout the study period, chiefly involving LDL cholesterol which fell from 227 mg/dl to 192 mg/dl. Total HDL cholesterol remained essentially unchanged with a mean of 25 mg/dl. These changes were accompanied by a reduction in apolipoprotein A1 from 118 mg/dl to 109 mg/dl and in B from 212 mg/dl to 204 mg/dl. Parameters of whole blood viscosity decreased significantly, while plasma viscosity remained unchanged. The conclusion which may be drawn is that supplementation with fish oil in addition to the normal food intake of dialysis patients contributes to an improvement in lipoprotein metabolism and so may reduce long-term cardiovascular risk factors.

Blood Viscosity↗
PubMed1991

[Low molecular weight heparin: how does it modify lipid metabolism in chronic hemodialysis patients?].

22 patients on chronic hemodialysis underwent low-molecular-weight-heparine (LMWH) (Fragmin, Kabi Chemie Corp., München) instead of conventional heparine (CH) for anticoagulation during dialysis. Blood evaluations before start, 2, 4 and 6 months under LWMH treatment and 3 and 6 months after switching back to CH were performed. During LWMH-treatment whole cholesterol decreased significantly, LDL-cholesterol being the main part accounting for this. HDL-cholesterol and the subfractions of HDL-cholesterol remained nearly unchanged. The apolipoproteins A1 and B decreased significantly, too. Apolipoprotein B decreased during the 6 months LMWH-period continuously, while Apolipoprotein A1 rapidly decreased during the first two months and then stabilized at a lower level. The triglycerides, starting from a normal range level, increased during the first 2 months significantly, then decreased reaching the starting values again at the end of the LMWH-period. Platelet aggregation induced with collagen showed a significant improvement during the use of LMWH. After switching back to CH the parameters returned to the starting values again.

Adult↗
PubMed1987

Influence of preanalytical factors on the atomic absorption spectrometry determination of trace elements in biological samples.

In the analysis of the concentration of trace elements in biological material there are many possible preanalytical sources of error. Precision and accuracy of trace element analyses are not so much determined by the analytical procedure--atomic absorption spectrometry--as by individual biological factors, contamination and loss of elements during sampling and sample preparation, influences resulting from the calibration procedure, or from the analytical equipment itself. Genetical factors like sex or race, ecological factors like age or pregnancy and short term factors like food intake, parenteral feeding or drug therapy can influence the final results. Different blood sampling methods with different duration and strength of compression may lead to hemolysis resulting in falsely elevated values of trace elements. Needles, syringes and tubes contribute to contamination by leaching trace elements from their walls or lead to loss of material by adsorption to the surface of the walls. As there is still no primary standard in order to guarantee precision and accuracy the calibration procedures have to be compared individually depending on the different matrices of the sample.

Calibration↗
PubMed1986

[Automated technics in microbiological diagnosis compared with conventional methods].

Two different tools for automation in medical microbiological diagnosis were tested. The results of biochemical identification of bacteria and antimicrobial susceptibility testing were compared with conventional methods--biochemical identification with Minitek and API 20 E and susceptibility testing wih the nutrient agar diffusion test. Sceptor from Becton Dickinson is usable because of a good accordance with conventional methods and the good quality of the associated computer program (different types of statistical evaluation). The 'fully automated' MS 2 from Abbott has more limitations and is more expensive in material, but is able to give a diagnosis in few hours, if a pure culture is available. Differences to conventional methods are greater.

Anti-Bacterial Agents↗