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Biomedical subjects

C Falkner

Publications and source records attributed to C Falkner.

7 recordsLinked to original sources
PubMed1998

Optimizing frequency and number of controls for automatic multichannel analyzers.

Sampling strategy fundamentally influences the effectiveness of quality control with control charts. This study shows a simple approach for optimizing the control strategy for automatic multichannel analyzers that takes into account cost-efficiency considerations. Our main focus is on the frequency of controls necessary. The methods used are based on a field study (on a Hitachi/BM 747), the views of experts, and computer simulations of customary cost-models together with a survey of the literature. We found that industrial cost-models are applicable only with distinct limitations, but-unlike the test-yield model-they offer consistent solutions. On the basis of the field study and the opinions of experts, we adjusted the control strategy to account for inadequacies in the theoretical models. The combined result is that, for effective operation, the number of samples between controls may reach values up to 100 and should not require controls more often than every 30 samples on comparable multichannel analyzers. For adequate statistical performance, a simple 3-SD Shewhart chart usually requires not more than two controls of the same material at each time.

Autoanalysis↗
PubMed1993

Zinc supplementation stimulates tetanus antibody formation and soluble interleukin-2 receptor levels in chronic hemodialysis patients.

Immunodepression in end-stage renal disease has been associated with zinc deficiency. In a controlled study serum zinc levels, serum concentrations of soluble interleukin-2 receptor (sIL-2R), and tetanus IgG antibody titers were measured in 65 hemodialysis patients before and after intravenous zinc supplementation for 2 months. The hemodialysis patients had significantly lower predialysis serum zinc concentrations compared to healthy controls (63 +/- 1.65 versus 126 +/- 4.6 micrograms/dl, P < 0.001). Serum zinc concentrations increased to the normal range in the zinc-treated patients. After zinc substitution tetanus antibody titers rose significantly (0.81 +/- 0.12 versus 1.22 +/- 0.12 U/ml, P < 0.01). Pretreatment sIL-2R levels were elevated in 95% of examined patients. A further increase in sIL-2R was observed after zinc supplementation (234 +/- 14 versus 285 +/- 21 U/ml, P < 0.05). The results suggest that zinc induces the activation of T lymphocytes and T-cell dependent B lymphocytes in chronic uremic patients in vivo.

Aged↗
PubMed1993

Advantages of the new loop diuretic torasemide over furosemide in patients with cirrhosis and ascites. A randomized, double blind cross-over trial.

Torasemide is a new loop diuretic with a longer half-life and longer action than furosemide in healthy subjects. In order to evaluate the pharmacodynamic effects, single oral doses of furosemide (80 mg) and torasemide (20 mg), which were equipotent in healthy subjects, were given to 14 patients with cirrhosis and ascites. Before the study patients underwent an equilibration period of 4 days without diuretics. The drugs were alternated following a randomized double-blind cross-over design after a wash-out period of at least 2 days. Urine was collected at defined intervals for 24 h after drug administration and blood samples were taken before, 6 h and 24 h after medication. Torasemide induced greater cumulative 24 h diuresis (2863 +/- 343 vs. 2111 +/- 184 ml, p < 0.01) than furosemide. Torasemide did not differ from furosemide for cumulative 0-6 h sodium excretion (96 +/- 17 vs. 92 +/- 23 mmol sodium) but caused a more pronounced cumulative 6-24 h natriuresis (38 +/- 11 vs. 17 +/- 4 mmol, p < 0.05). Five patients exhibited a weak response to furosemide (0-36 mmol sodium/24 h, median 24 mmol; 690-1460 ml urinary volume/24 h, median 1325 ml). These patients showed significantly higher natriuresis and diuresis following torasemide (26-136 mmol sodium/24 h, median 78 mmol, p < 0.05; 1670-3610 ml urinary volume/24 h, median 2200 ml, p < 0.05). Twenty-four hours after administration of both drugs there were no significant changes in hemodynamic, renal or hormonal parameters. No adverse effects were noted with either treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

[Effect of zinc substitution on lymphocyte subsets and cellular immune function in hemodialysis patients].

Infection is a major cause of morbidity and mortality in patients undergoing hemodialysis for end stage renal disease. Low plasma zinc levels have been associated with immunodepression in these patients. In a randomized, placebo controlled double-blind cross over study, plasma zinc levels, delayed hypersensivity to 7 Antigens (Merieux-Multitest), absolute lymphocyte counts, T- and B-lymphocytes, suppressor-T and helper T-cells and natural killer cells were studied in 25 hemodialysis patients before, during and after intravenous zinc supplementation for 8 weeks. The hemodialysis patients had significantly lower predialysis plasma zinc concentrations compared to 76 healthy controls (74 +/- 12 vs. 126 +/- 28 mcg/dl, p less than 0.001). The plasma zinc concentrations increased to the normal range during the treatment period. Lymphocyte subtype analysis showed a significant decrease of suppressor-T cells and an increase of the helper-T/suppressor-T ratio (2.09 +/- 0.26 vs. 3.18 +/- 0.48, p less than 0.05) after zinc supplementation. Delayed hypersensivity to intradermal antigens increased significantly only after zinc treatment (2.0 +/- 0.7 vs. 5.8 +/- 1.7, p less than 0.05), not after placebo. The changes were reversible after finishing the zinc treatment. It is concluded, that plasma zinc levels are reduced in hemodialysis patients and that the substitution of zinc restores some of the depressed immune functions in these patients.

CD4-CD8 Ratio↗
PubMed1990

[Anti-ischemic action of the transdermally-applied beta-receptor blocker, mepindolol, in patients with stable angina pectoris. Comparison with transdermal nitrate].

A new transdermal beta-blocker containing system (Mepindolol BIO TSD) was compared in a placebo controlled cross over trial with a transdermal nitrate system in 14 patients suffering from coronary heart disease with stable angina pectoris. Under Mepindolol TSD both the incidence of angina pectoris attacks and the consumption of oral nitroglycerin dropped significantly. Under ergometry it resulted in an improvement in the maximum exercise tolerance and in a significant reduction in the ischemic ST-Segment deviation. Under Holter monitoring the number of manifest (MMI) and silent (SMI) ischemic episodes was significantly reduced. In addition the total duration of ischemia was significantly reduced. All the examined parameters showed Mepindolol BIO TSD to be significantly more effective than transdermal nitrate, and the duration of action was longer. No clinically relevant adverse events were observed in any of the therapeutic regimes.

Administration, Cutaneous↗
PubMed1986

Increased in vitro platelet aggregation in hypertriglyceridemias.

Platelet aggregation induced by ADP and collagen was monitored in 25 patients with increased serum levels of triglycerides (7 HLPs type IIb, 14 type IV, 4 type V patients) and compared with a group of 10 normolipidaemic control persons. Platelet aggregation was studied simultaneously in platelet rich plasma (PRP) by both turbidometric and impedance technique and also in whole blood (WB) by the impedance method. Whereas platelet aggregation testing by turbidometry was limited by the optical density of the plasma samples in hypertriglyceridemia, the aggregation process could easily be registered in PRP and WB using the impedance method. Threshold aggregatory concentrations with both agonists were significantly lower for all three groups of HLP.

Adenosine Diphosphate↗