Bent Nielsen

On the Exudation of Plasticizers from PVC Haemodialysis Tubings

Prompted by a series of hepatitis-like cases in patients on regular haemodialysis treatment, the sets of polyvinylchloride (PVC) test tubings used were submitted to perfusion experiments. The perfusates from four commercially available tubings were also investigated. Diethylphthalate (DEP) could be identified by by IR and PMR spectrometry in the perfusate from the test tubings. UV spectrometry proved the presence of other non-identified substances in the perfusate from both the test tubings and from some of the other tubings.

The Effect of Erythropoietin on Platelet Function and Fibrinolysis in Chronic Renal Failure

The influence of erythropoietin therapy on platelet function and fibrinolysis was evaluated in 12 anemic hemodialysis patients. Six months of therapy with human erythropoietin (50 to 80 IU/kg initially) raised the hemoglobin level to 10.8 g/dl but did not increase platelet activity in vivo as measured by beta-thromboglobulin or platelet factor 4. There was no change in the platelet aggregation thresholds in vitro for ADP, adrenaline, thrombin or collagen during treatment. Platelet number and volume were also unaffected. Fibrinolytic activity intensified as erythropoietin treatment proceeded, with a fall of euglobulin clot lysis time and rise in the activity of t-PA. PAI-1 levels also showed a downward trend, without reaching significance. Thus erythropoietin treatment in modest doses does not seem to adversely influence the hemostatic system in patients on hemodialysis.

Effects of recombinant human erythropoietin on the haemopoietic bone marrow monitored by magnetic resonance spectroscopy in patients with end-stage renal disease

Volume selective magnetic resonance (MR) proton spectroscopy was used to investigate changes in the haemopoietic bone marrow in patients with end-stage renal disease undergoing treatment with recombinant human erythropoietin (rHuEPO). Significant changes could be detected in the spectra 14 days after the beginning of treatment, before any response was seen in the haemoglobin concentration of peripheral blood. The spectral changes indicate an alteration in cellular composition of haemopoietic bone marrow with an increase in the amount of haemopoietic active tissue. One patient showed a major change in the spectrum four days after treatment began, indicating that MR spectroscopy may detect early changes in the cellular composition of the bone marrow. This noninvasive method may be useful in evaluating treatment effects of recombinant human haemopoietic growth factors in the bone marrow, as well as investigating bone marrow response from different modes of rHuEPO administration.

Magnetic resonance imaging of the bone marrow following treatment with recombinant human erythropoietin in patients with end-stage renal disease.

We used magnetic resonance imaging (MRI) to study vertebral bone marrow in hemodialysis patients during treatment with recombinant human erythropoietin (rHuEPO). We found changes in T1 relaxation times and image contrast within 14 days after starting treatment, before any response was seen in the hemoglobin concentration in peripheral blood. The increase in T1 relaxation times, together with earlier reported changes observed with localized magnetic resonance spectroscopy, indicate an alteration in cellular composition of the hemopoietic bone marrow with an increase in the amount of hemopoietic active tissue. MRI may be a useful, non-invasive way of evaluating bone marrow response to different modes of rHuEPO administration and dosage.

Lack of Relationship between Parathyroid Hormone and 1,25-Dihydroxyvitamin D in Chronic Renal Failure

In the present study, concentrations of parathyroid hormone (PTH), determined by an intact PTH assay and a midregion/C-terminal PTH assay, 1,25-dihydroxyvitamin D [1,25(OH)2D3], ionized calcium and phosphate were measured in 15 patients with a stable creatinine clearance (Ccr) of 21.2 +/- 14.4 ml/min (mean +/- SD; group 1) and in 10 patients with a Ccr regularly undergoing hemodialysis (group 2, Ccr not measured). In group 1, the mean concentration of 1,25(OH)2D3 was significantly increased compared with the level in group 2, whereas no differences were found concerning the concentrations of intact PTH, midregion/C-terminal PTH, ionized calcium and phosphate. In group 1, the PTH concentration correlated inversely with ionized calcium concentration and Ccr, which in turn, was directly correlated. The concentration of 1,25(OH)2D3 correlated inversely with phosphate concentration, but did not correlate with either PTH or ionized calcium concentrations. In group 2 no correlation was found between any of the biochemical variables. The data demonstrate that in patients with stable renal failure, the concentration of ionized calcium still regulates PTH secretion but other variables such as parathyroid cell mass and setpoint may interfere with the interrelation. The elevated concentration of phosphate in renal failure may override PTH as a regulator of the renal 1,25(OH)2D3 formation. The lack of correlation in the hemodialyzed patients may be attributed to extrarenal production of 1,25(OH)2D3, reduced binding of 1,25(OH)2D3 to parathyroid tissue or the major changes in calcium homeostasis caused by the hemodialysis.

THE RELEASE OF PLASTICIZERS FROM PVC TUBING.

Publisher Summary During test runs with a new Danish haemodialysis monitoring system in three patients it has been observed that the patients exhibited abdominal distress the intensity of which increased with the length of the treatment and the number of consecutive dialysis runs. The chapter discusses this phenomenon. Liver function tests were found to be increasingly abnormal with overt jaundice in one case. The symptoms disappeared on returning to the equipment ordinarily used in the unit, only to return on the resumption of the test runs. As the monitor is found normal, the new PVC-tubings are submitted to perfusion experiments with subsequent analysis of the perfusates for their content of plasticizers. The infrared and proton magnetic resonance spectra unequivocally disclosed the leakage of diethylphthalate from the new PVC tubings, a substance the presence of which is not demonstrated in the perfusates from a series of commercially available dialysis tubings. The chapter describes the methods used and the results of a series of investigations aimed at clarifying the release of this abnormal constituent of the PVC tubings.

Cycles and Sequences of the Eight Trigrams

This article investigates the original Chinese sources for two circular trigram arrangements that have played a crucial role in numerology associated with the Book of Changes (the Yijing 《易經》) since the Song dynasty (960–1279). While attempting to clarify the nature and the origins of these and related diagrams, recent secondary literature on topic is reviewed, especially the influential articles by Schuyler Cammann.