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Biomedical subjects

K Schaefer

Publications and source records attributed to K Schaefer.

At least 55 records · Page 3Linked to original sources
PubMed1990

Calcium ketovaline as new therapy for uremic hyperphosphatemia.

Since treatment of uremic hyperphosphatemia still represents a major problem and phosphate-binding agents carry the well-known risk of aluminum intoxication, we carried out a study to determine whether calcium ketovaline, a keto acid containing calcium, would show phosphate-binding effects comparable to those obtained with a mixture of amino acids and calcium salts of ketoanalogues tested previously. In vitro as well as in vivo studies show convincingly that calcium ketovaline is a valuable intestinal phosphate binder. Dialysis patients treated for 6 weeks showed a significant (p less than 0.05) decrease in serum phosphate from 2.36 +/- 0.19 to 1.81 +/- 0.16 mmol/l.

Hemiterpenes↗
PubMed1990

Influence of membranes on generation of beta 2 M and release of leukocyte lysosomal enzymes.

Normal leukocyte functional capacity was investigated by evaluation of phagocytosis of opsonised yeast cells in a radiometric test system. After incubation with dialysis membranes (different cellulosic membranes, polysulfon membrane (PS), polymethylmetacrylate membrane (PMMN), the phagocytosis index, expressed as percent decrease with respect to initial values without membrane, decreased by 10%-25%. The most pronounced effect was observed with PS, cuprophane, modified cellulose and PMMA. The results are not related to differences in the viability of PMN during the test procedure; dead PMN amounted to about 4-6.5%. A significant increase in beta-NAG and beta-Gluc activities was released in the supernatants of the phagocytosis suspensions. This increase activity can be explained by the phagocytosis of PMN but it was not influenced by membrane contact. There was no influence of membrane contact or phagocytosis activity of PMN on the beta 2 M concentration in the supernatant demonstrating that no in vitro generation during incubation with either membrane exists.

Acetylglucosaminidase↗
PubMed1989

Acute renal failure due to uric acid nephropathy in a patient with renal hypouricemia.

This report is about a 23-year-old man who required hemodialysis in connection with an acute renal failure resulting from uric acid nephropathy without hyperuricemia. After recovering renal function he showed extreme hypouricemia (0.1-0.3 mg/dl) and elevated uric acid clearance (100-300 ml/min). The fractional excretion of uric acid (Cua/Ccr) could be suppressed by oral pyrazinamide and enhanced by probenecid. As no other renal tubular or metabolic abnormalities were detected, it is suggested that a markedly increased renal tubular urate secretion was responsible for the hypouricemia and also for the rare side-effect of an uric acid nephropathy in this patient.

Acute Kidney Injury↗
PubMed1989

Visual cerebral lateralization over phases of the menstrual cycle: a preliminary investigation.

This study investigated whether visual cerebral asymmetries would change in phase with hormonal variations during the menstrual cycle. Lexical decision and line orientation tasks were administered during follicular, luteal, and menstrual phases of each woman's cycle. These tasks were also administered to a reference group of male subjects. Signal detection analyses indicated an unvarying RVF advantage in word/nonword discriminability (d') throughout the menstrual cycle, but a phase-dependent shift in left hemisphere response criterion (log beta). Gender differences were present for discriminability of line orientation, and female performance on this task varied over the cycle. The results imply that the neural systems subserving some cognitive functions are sensitive to fluctuations in gonadal steroids and suggest a hormonal basis for gender differences in some visual-spatial functions.

Adolescent↗
PubMed1989

Dietary treatment as seen by German nephrologists. Results of a questionnaire.

The majority of German nephrologists consider a protein restriction for patients with advanced renal failure as necessary. However, there was no consensus with regard to the diet, which should be finally applied. It was of further interest that the majority of physicians believe that only 50% of their patients adhere consistently to the diet.

Dietary Proteins↗
PubMed1989

Atrial natriuretic peptide plasma levels during hemodialysis and hemofiltration in patients with end-stage renal disease.

Using a cross-over protocol we repeatedly measured the plasma levels of alpha-hANP (atrial natriuretic peptide) during one week by radio-immunoassay in eight patients with end-stage renal disease treated with chronic hemodialysis or hemofiltration. Before each hemodialysis or hemofiltration session mean plasma ANP levels (353 +/- 112, and 337 +/- 99 pg.ml-1, respectively) were significantly above normal (50 - 166 pg.ml-1). In all but one patient, the values fell significantly towards but not reaching the normal range. Plasma ANP concentrations returned to normal at the end of the treatment in only two of the eight subjects. There was a positive correlation between the increase in body weight from one treatment to the next and the plasma ANP concentration (r = +0.35, p less than 0.05). The net loss of fluid volume during each treatment did not correlate significantly with the change in plasma ANP levels. There was no difference between hemodialysis and hemofiltration. Plasma ANP measurement may be helpful in the judgement of volume status in patients with end-stage renal disease treated by hemodialysis or hemofiltration.

Adult↗
PubMed1989

Calcium salts of ketoacids as a new treatment strategy for uremic hyperphosphatemia.

Hyperphosphatemia and secondary hyperparathyroidism are regular complications in patients suffering from end-stage renal failure. Aluminum-containing drugs are widely used to control serum phosphate, but this therapy carries the well-known risk of aluminum toxicity. Previously we demonstrated that a mixture of ketoacids is very effective in lowering increased serum phosphate and serum PTH levels. Recent studies to clarify the underlying mechanisms whereby these compounds lower serum phosphate revealed that ketoacids act as intestinal phosphate binders. In balance studies we demonstrated that intestinal phosphorus uptake decreased in normal subjects (decrease of absorption during ingestion: 0.7-3.14 mmol/day). Additional in vitro studies not only confirmed the in vivo results but also showed that ketoacids are as efficient as calcium carbonate although they provide less calcium. It is of further interest that ketoacids reached their greatest binding efficiency when the pH is 7.0, whereas calcium carbonate binds phosphate predominantly when the pH is 2.0 or 5.0. Ketoacids represent a further therapy to lower serum phosphate in uremia. As they provide less calcium than calcium carbonate, they could be considered as an advantageous, less dangerous alternative.

Absorption↗
PubMed1989

[Clinical significance of beta 2 microglobulin determination in dialysis patients].

In radioimmunological estimation of beta 2-microglobulin significant higher serum values were found in 36 dialysis patients (44.4 +/- 20.3 mg/l) in comparison with healthy probands (1.5 +/- 0.2 mg/l). A significant relation to the duration of dialysis, rest diuresis and serum level of aluminium was found. Significant higher concentrations were observed in patients suffering from pain in the shoulder-limb-region and with ostealgia in other regions, but not in radiological verified destructive arthropathy and spondylarthropathy. The used dialyzers MLW 1.3/1.8 m2 did not eliminate the beta 2-microglobulin from the blood.

Adult↗
PubMed1988

Treatment of uremic hyperphosphatemia--is there still a need for aluminum salts?

Aluminum-containing phosphate binders have been widely employed in the past in the management of uremic hyperphosphatemia. However, an increasing number of reports on aluminum toxicity has stimulated efforts to replace this therapy by safer methods. The aim of the present review is to critically evaluate other treatment strategies. It appears that aluminum-containing phosphate binders should no longer be considered the treatment of choice for controlling uremic hyperphosphatemia. Calcium carbonate, calcium citrate, magnesium carbonate and a mixture of ketoanalogues and amino acids present important therapeutical alternatives which could replace aluminum-containing phosphate binders in the majority of patients. However, it is mandatory, as these therapies also carry some risks, that side effects are detected early.

Alum Compounds↗
PubMed1988

Good biocompatibility of the polyamide hemofilter.

Chronic hemofiltration (HF) is now a well-established method, especially for elderly uremic patients and those suffering from cardiovascular problems. This is due to the fact that chronic HF offers superior treatment comfort with less hypotensive episodes, vomiting, muscle cramps and febrile reactions. Apart from the different blood purification techniques involved in chronic HF compared to hemodialysis (i.e. convection versus diffusion), it might well be that the better treatment comfort is attributable to a certain extent to the polyamide HF membrane used in our HF treatments. We studied different biocompatibility parameters and received the following data: (a) leukocytes and thrombocytes remained unchanged during a treatment session; (b) elastase increased slightly but there was no difference between the polyamide and polycarbonate membrane, and (c) arterial and venous concentrations of C5a and C3d remained almost unchanged. The superior treatment comfort and better vascular stability of HF over hemodialysis might also be due to the improved biocompatibility of the applied hemofilter as the polyamide membrane induces no changes in different biocompatibility parameters such as leukocytes, thrombocytes, C5a or C3d.

Biocompatible Materials↗
PubMed1988

Glomerular filtration rate in response to an acute protein load.

The effect of a protein load on the glomerular filtration rate (measured as creatinine clearance) was studied in normal subjects, healthy vegetarians, patients with advanced liver disease, patients with moderate renal failure and in normal volunteers being pretreated with aspirin or sulindac. Only patients with liver disease were not capable of increasing their glomerular filtration rate after the protein challenge, a finding which suggests that the liver might be of importance for the adequate renal reserve. It is of note that neither the application of nonsteroidal anti-inflammatory drugs nor the existence of a moderate renal failure modify the response to a protein load.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed1988

Different handling of beta 2-microglobulin during hemodialysis and hemofiltration.

Very recently it was reported that the amyloid associated with chronic hemodialysis contains, as a major component, a new form of amyloid fibril protein which is homologous to beta 2-microglobulin. As beta 2-microglobulin has a molecular weight of 11,600 daltons, investigations were carried out to see whether or not this protein would be handled differently by hemodialysis and hemofiltration, because the latter method especially is capable of eliminating solutes with such a high molecular weight. The results clearly indicate that hemofiltration removes substantial amounts of beta 2-microglobulin (about 190 mg per treatment, which represents 80% of daily production). It remains to be clarified whether or not hemofiltration is therefore superior to hemodialysis with regard to amyloid deposit formation.

Cellulose↗