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Biomedical subjects

K Schindhelm

Publications and source records attributed to K Schindhelm.

66 records · Page 4Linked to original sources
PubMed1979

Peptide hormones: renal handling and dialysis therapy.

For uraemic diabetics the loss of insulin by dialysis with highly permeable membranes has clinical relevance. We investigated renal handling (in isolated perfused rat kidneys) of insulin and c-peptide and their dialytic clearances and sieving coefficients using cuprophan and polyacrylonitrile membranes. Rat kidney catabolic clearances were five times (insulin) and 12 times (c-peptide) greater than urinary clearances and twice inulin clearance. Cuprophan membrane was found to be virtually impermeable for both hormones. Polyacrylonitrile sieving coefficients were 0.3 (insulin) and 0.4 (c-peptide). Both hormones are filtered as well as tubularly and peritubularly catabolised in the kidney. Insulin removal during dialysis and haemofiltration with polyacrylonitrile membranes has to be considered in treating uraemic diabetics.

Animals↗
PubMed1978

Precise anticoagulation for routine hemodialysis.

A pharmacokinetic model for minimal dose heparinization for chornic hemodialysis patients was recently described by Gotch and Keen. The model requires the determination of two parameters: dose sensitivity (computed for a given heparin dose from increase in WBPTT above a baseline value) and the heparin elimination constant. This study describes the extension of this model to the more precise control of anticoagulation during routine dialysis. S and K were measured in 30 stable chronic dialysis patients and were found to differ markedly (0.015 less than or equal to S 0.08 sec/unit; 0.04 less than or equal to K less than or equal to 1.7 hr-1). The mean S value was 0.041 +/- 0.002 sec/unit (N = 30) and the mean K value was 0.90 +/- 0.06 hr-1 (N = 30). In addition, the mean t 1/2 of heparin obtained in the group of 30 patients from individual rate constants was 0.86 +/- 0.06 hr, in excellent agreement with values obtained in normal subjects given similar doses of the drug. Variations in sensitivity during dialysis were minimal, but variations in elimination rate of up to 50% were encountered during modeling. However, the large variations in K did not affect the applicability of the model of control clotting times during dialysis when infusion requirements were based on mean values of S and K taken over four to five dialyses. In an initial group of five patients, whose heparin requirements were reduced by an average of 38% +/- 20 (range 13% to 65%), there was no significant change in the degree of dialyzer clotting in comparing premodeling and postmodeling heparin therapy. In most of the remaining patients (N = 22) the pattern was similar: a reduction in total heparin administration without increased dialyzer clotting. In three patients (10%) over-all heparin dose had to be moderately increased (3% to 13%). Heparin modeling has been successfully applied to routine anticoahe technique cannot be extended to other clinical procedures involving either intermittent or continuous infusion of heparin. To assist in the application of heparin modeling, nomograms have been developed.

Blood Coagulation Tests↗
PubMedDate not supplied

Beta 2-microglobulin kinetics in an ovine model.

The kinetics of 125I-beta 2 microglobulin (beta 2M) and 51Cr-EDTA were measured in normal and nephrectomized sheep. In normal sheep the beta 2M clearance was similar to that of EDTA (i.e., glomerular filtration rate), as were the distribution volumes. In anephric sheep the beta 2M clearance was 7.7 +/- 1.4 ml/min.

Animals↗
PubMedDate not supplied

Anterior cruciate ligament graft fixation. Initial comparison of patellar tendon and semitendinosus autografts in young fresh cadavers.

The initial biomechanical properties of semitendinosus and patellar tendon autografts and their fixation strengths were investigated. Twenty fresh cadaveric knees from donors under 42 years of age were used in the study. After removing all soft tissues other than the anterior cruciate ligament, we determined the ultimate tensile strength (2195 +/- 427 N) and stiffness (306 +/- 80 N/mm) of the anterior cruciate ligament in nine knees. In six knees, anterior cruciate ligaments were reconstructed using an autologous patellar tendon graft with proximal and distal interference fit screws; this resulted in an ultimate tensile strength of 416 +/- 66 N. Five knees were reconstructed with quadruple-stranded (double-looped) semitendinosus tendons fixed proximally by a titanium button and braided tape and distally by tibial post screw. This resulted in an ultimate tensile strength of 612 +/- 73 N, which was significantly higher than the strength in the patellar tendon group. Graft stiffness did not differ between the groups and was 47 +/- 19 N/mm (N = 11). This study demonstrates that the reconstructed knees had only 20% to 30% of the ultimate tensile strength of the normal anterior cruciate ligament. In summary, the semitendinosus reconstruction using a button for proximal fixation is, at the time of surgery, approximately 50% stronger than patellar tendon reconstructions with similar stiffness.

Adult↗
PubMedDate not supplied

Plasma water filtration and lymphatic uptake during peritoneal dialysis.

To clarify further the extent, pathways, and significance of convective transport during peritoneal dialysis, acute transport studies were conducted in which five continuous ambulatory peritoneal dialysis (CAPD) patients underwent 6 hr dialyses (2 L infusate with 2.25% dextrose) on 2 successive days, with multiple sampling of both blood and peritoneal dialysate. Concentrations of permeants (urea, creatinine, uric acid, beta 2 microglobulin, and apolipoprotein A) and a radiolabeled marker (125I-polyvinyl pyrollidone [PVP]) were determined at 20-30 min intervals in dialysate and every 90 min in plasma. Intraperitoneal volumes and lymphatic flows were calculated from rates of dilution and disappearance of 125I-PVP. Intratreatment lymphatic flow rate averaged 76 +/- 15 ml/hr. Although lower than observed in small animal models and reported by some clinical groups, this level of lymphatic drainage was still sufficient to decrease net patient weight loss by approximately 50% and to resorb approximately 15% of metabolites in the peritoneal cavity, independent of molecular weight. Transcapillary ultrafiltration ranged from 7.4 +/- 1.5 ml/min at 10 min into the exchange to 1.3 +/- 1.5 ml/min at 345 min. Reverse ultrafiltration, from the peritoneal cavity back through capillary vasculature to the patient, was not observed in any patient in this study.

Ascitic Fluid↗