Biomedical subjects

M J Janssen

Publications and source records attributed to M J Janssen.

43 records · Page 3Linked to original sources

PubMed1993

Citrate versus heparin anticoagulation in chronic haemodialysis patients.

Anticoagulation with citrate at a rate of 0.68 mM/min in combination with a calcium and magnesium-free dialysate and i.v. supplementation of calcium and magnesium at rates of 0.18 mM/min and 0.08 mM/min respectively, was compared with low-dose heparin. The heparin dose was a loading dose of 2500 IU and a sustaining infusion of 750-1250 IU/h; or a loading dose of 1250 IU and a sustaining infusion of 500-750 IU/h until 1 h before the end of the dialysis if the patient was taking concomitantly coumarin anticoagulation for a Goretex shunt. Six chronic haemodialysis patients changed from heparin to citrate anticoagulation because they reported bleeding between dialyses. Heparin, after 2 h dialysis, induced a significant 10% prolongation of each patient's whole-blood activated clotting time (WBACT) as compared to the predialysis value; while the WBACT at the dialyser outlet was less than 3% prolonged as compared to the patient's WBACT. However, after 2 h citrate the patient's WBACT was not prolonged but the WBACT at the dialyser outlet was 20-100% longer, indicating a better anticoagulation of the extracorporeal system without systemic effects. With heparin the shunt pressure time (SPT), i.e. the time needed to stop bleeding from the puncture sites of the Goretex shunts, was 12 of 28 times 20 min or more. Citrate reduced these episodes by 75%. Thus citrate should be considered for chronic haemodialysis patients who are at risk of bleeding because of the concomitant use of anticoagulants.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗

PubMed1992

An evaluation of interventions designed to stimulate physician reporting of adverse drug events.

A frequent complaint among health care professionals about ADE reporting programs is that they never know what happens to the information they took the time and effort to report. In the Mississippi ADE program, physicians appreciated the feedback they were provided--in letter form--indicating the ultimate disposition of the reported information. Also, a regular newsletter summarizing the number and types of reports and the drugs involved was well received. This vehicle was also used to educate physicians about new drugs on the market that warranted closer scrutiny. Reminder posters placed at strategic points around the hospital and periodic inservices on the program are effective in maintaining a level of awareness about the importance of ADE monitoring and its impact on the quality of care.

Adverse Drug Reaction Reporting Systems↗

PubMed1992

Citrate anticoagulation and dialysate with reduced buffer content in chronic hemodialysis.

Anticoagulation with trisodium citrate (510 mmol/l) at a rate of 126 ml/h in combination with a calcium-free, 35 mmol/l acetate dialysate and i. v. supplementation of calcium chloride (350 mmol/l) at a rate of 22.5 ml/h has been performed in renal failure patients at risk of bleeding or actively bleeding. Short-term use-i. e. on the average four dialyses in 15 patients-showed no adverse effects or clotting phenomena. However, long-term use-i. e. at least four weeks and on average sixteen dialyses in six chronic hemodialysis patients-caused paresthesias and muscular cramps possibly due to the combination of insufficient calcium supplementation and metabolic alkalosis. To prevent metabolic alkalosis, the acetate content of the dialysate and the infusion rate of citrate were reduced to 29.5 mmol/l and 100 ml/h, respectively. To prevent clotting at this infusion rate, a calcium and magnesium-free dialysate was used and i. v. supplementation of calcium chloride (350 mmol/l) and magnesium chloride (250 mmol/l) was performed at rates of 30 ml/h and 15 ml/h, respectively. Six chronic renal failure patients were dialyzed with this regimen for an average of four months. There were no side effects or metabolic alkalosis noted. When an equimolar amount of bicarbonate replaced the acetate in the calcium and magnesium-free dialysate, side effects and metabolic alkalosis were seen within three dialyses. When the bicarbonate concentration in the dialysate was reduced to 25 mmol/l neither side effects nor metabolic alkalosis was observed. Thus citrate anticoagulation in patients on chronic hemodialysis can only be performed when the buffer content of the dialysate is reduced.

Acetates↗

PubMed1991

Adrenocortical insufficiency: a rare presentation of non-Hodgkin's lymphoma.

A 77-year-old man presented with adrenocortical insufficiency, for which a cause could not be identified during life. Six weeks after the diagnosis, the patient died, while receiving adequate cortisol therapy, from a fulminant gastrointestinal bleeding. A pleural effusion, found shortly before death, later showed malignant lymphoid cells. At autopsy, a widely spread, diffuse, malignant B-cell lymphoma with destruction of, amongst others, both adrenals was found. The retroperitoneal, but not the peripheral lymph nodes were involved, thereby explaining failure of diagnosis while the patient was living. This is the first description of a diffuse B-cell Non-Hodgkin's lymphoma presenting with adrenocortical insufficiency. Potentially curable malignant invasion of the adrenals can present with adrenocortical insufficiency, and may thus justify imaging of the adrenals with sensitive techniques in elderly patients with unexplained primary adrenocortical insufficiency.

Adrenal Cortex Diseases↗

PubMed1984

Cloning of a third nitrate reductase gene from the cyanobacterium Anacystis nidulans R2 using a shuttle cosmid library.

A strategy for gene cloning in the cyanobacterium Anacystis nidulans R2 was developed which made use of a gene library constructed in a shuttle cosmid vector. The method involved phenotypic complementation of mutants with pooled cosmid DNA. The development of the procedure and its application to the cloning of a third gene involved in nitrate reduction are described.

Bacterial Proteins↗

PubMedDate not supplied

Isolation and characterization of highly purified mitochondrial outer membranes of the yeast Saccharomyces cerevisiae (method).

Mitochondrial outer membrane vesicles (OMV) from the yeast Saccharomyces cerevisiae were prepared by osmotic swelling and mechanical disruption of mitochondria that had been isolated at pH 6.0 and purified by density gradient centrifugation. The OMV were obtained in a yield of 1% (protein/protein) with respect to the mitochondria. The OMV were shown to be essentially free of mitochondrial inner membrane protein markers, while contamination with endoplasmic reticulum was around 5% (protein-based). The very low phosphatidylserine synthase activity present in the OMV preparation indicated that contamination with mitochondria-associated membranes (MAM) was negligible. The resistance of the outer membrane protein Tom40 to digestion by trypsin demonstrated the sealed nature and right-side out orientation of the OMV. Analysis of the phospholipid composition revealed that the contents of phosphatidylcholine and phosphatidylinositol are higher and the content of phosphatidylethanolamine is lower in the mitochondrial outer membrane as compared to whole mitochondria. Cardiolipin is largely depleted in the OMV.

Cell Fractionation↗

PubMedDate not supplied

Folic acid treatment of hyperhomocysteinemia in peritoneal dialysis patients: no change in endothelial function after long-term therapy.

BACKGROUND: Hyperhomocysteinemia occurs in renal failure and may increase the risk for cardiovascular disease, possibly by damaging the endothelium. Folic acid and betaine are required in two separate homocysteine conversion pathways and may therefore lower plasma homocysteine. OBJECTIVE: To study the therapeutic role of betaine and the effect on endothelial function of long-term homocysteine-lowering therapy with folic acid, in peritoneal dialysis (PD) patients. PATIENTS AND DESIGN: Thirty PD patients were randomized to a 12-week treatment with 5 mg folic acid and 4 g betaine daily, or to 5 mg folic acid alone daily. They were then rerandomized to treatment with 1 or 5 mg folic acid daily for 40 weeks. MEASUREMENTS: At baseline and after 52 weeks, endothelial function was assessed by determination of endothelium-dependent vasodilatation and biochemical markers. RESULTS: Plasma total homocysteine (tHcy) was elevated at baseline: 42.6 (5.8) micromol/L. Only 1 patient (3%) had a normal plasma homocysteine (i.e., < or = 15 micromol/L) before therapy. Normalization of plasma homocysteine occurred in 39% of the patients at 12 weeks. Betaine had no additional homocysteine-lowering effect. Plasma tHcy levels were similar during treatment with 1 or 5 mg folic acid daily. Endothelial function was impaired at baseline and had not improved after 52 weeks of treatment. CONCLUSIONS: Peritoneal dialysis patients have hyperhomocysteinemia, which can be normalized with folic acid alone in about 40% of patients. Betaine does not further lower plasma homocysteine. A maintenance dose of 1 or 5 mg folic acid daily results in equivalent plasma homocysteine levels. Long-term reduction in plasma homocysteine did not result in improvement of endothelial function as assessed by our methods.

Betaine↗