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R M Schaefer

Publications and source records attributed to R M Schaefer.

160 records · Page 9Linked to original sources
PubMed1987

Acute uremia following dietary potassium depletion. II. Effect on tissue carbohydrate composition.

In order to evaluate the potential role of hyperkalemia and metabolic acidosis on the disturbances of carbohydrate metabolism normally seen in uremia, a specific model of acute uremia devoid of hyperkalemia and severe metabolic acidosis was chosen. Therefore, rats were deprived of potassium prior to induction of acute uremia. Potassium depletion caused a significant decrease of muscle and liver glycogen due to activation of phosphorylase kinase, whereas glycogen concentration in heart muscle was unchanged and elevated in the kidney of sham-operated and ureter-ligated animals. In contrast, glucose concentrations were enhanced in the liver and the kidney, unchanged in heart muscle and decreased in skeletal muscle. We conclude that carbohydrate abnormalities occur in acute uremia despite normokalemia and mild metabolic acidosis. Furthermore, acute uremia accompanied by prior potassium depletion results in no net effect on cardiac glycogen metabolism but stimulates glycogenolysis in both skeletal muscle and the liver.

Animals↗
PubMed1986

Improvement of dialyzer compatibility by reduction of membrane surface area.

The present study was devised to investigate, whether reduction of membrane surface area would contribute to enhanced dialyzer membrane compatibility. Therefore, 10 hemodialysis patients were dialyzed with three different cuprophan dialyzers, displaying membrane surface areas of 0.9 m2, 1.2 m2, and 1.8 m2. As an index of biocompatibility release of granulocyte elastase and secretion of granulocyte lactoferrin were determined by enzyme-linked immunoassays. With the three cuprophan membranes, marked leukopenia occurred 15 min after the start of hemodialysis, without significant distinction between the different membranes. On the other hand, the release of leukocyte elastase was strictly dependent on the membrane surface area. Thus, at the end of dialysis, plasma levels of elastase were as follows: 0.9 m2: 255 +/- 51; 1.2 m2: 356 +/- 65; 1.8 m2: 471 +/- 56 ng/ml. The magnitude of secretion of leukocytic lactoferrin was also dependent on membrane surface area. Therefore, the increment during dialysis was 300% with the 1.2 m2 membrane compared to 650% using a 1.8 m2 dialyzer. Based upon these data, we concluded that, using measurements of granulocyte degranulation as an index of biocompatibility, reduction of membrane area resulted in a marked improvement of membrane compatibility.

Adult↗
PubMed1986

Acute uremia following dietary potassium depletion. I. Effect on blood parameters related to carbohydrate metabolism.

The effect of an acute uremic state with normokalemia and only mild metabolic acidosis on blood metabolic intermediates related to carbohydrate metabolism was investigated in rats. Therefore animals were deprived of potassium by feeding a low-potassium diet for 4 weeks prior to induction of bilateral nephrectomy, ureteral ligation or hemoglobinuric acute renal failure. Potassium depletion in the setting of acute uremia resulted in increased plasma creatinine, urea nitrogen, and lower plasma glucose levels in comparison to normokalemic, acutely uremic rats. Plasma insulin became depressed only in potassium-depleted rats which had undergone ureteral ligation. Potassium depletion in both acute renal failure and sham-operated animals resulted in an increase in plasma lactate, pyruvate, and oxoglutarate. Ketone bodies decreased in potassium-depleted sham-operated rats, whereas acetoacetate levels increased significantly in potassium-depleted bilateral-nephrectomized animals.

Acute Kidney Injury↗
PubMed1985

Role of alcohol in clinical nephrology.

Different nephrological derangements are observed in severe alcoholics. Until now the direct toxicity of ethanol is only shown in the fetal alcohol syndrome with various malformations of the genitourinary tract. In the adult the kidney is often involved in the development, maintenance and counterregulation of complex electrolyte disturbances like phosphate and potassium hypoglycemia etc. The alcohol associated retention of urate, induced by hyperlactatemia and/or increased beta-hydroxybutyrate concentration is only rarely complicated by urate nephropathy. Alcohol intoxication (acute and chronic) predisposes to rhabdomyolysis with the risk of acute renal failure. There are some hints that chronic alcoholism with myopathy increases the vulnerability of the kidney for further toxic agents. In rats glycerol induced renal failure is enhanced by alcohol pretreatment. Finally, regular alcohol consumption raises the blood pressure, which per se is a risk factor for renal damage.

Acute Kidney Injury↗
PubMed1985

Effect of diuresis on urinary erythrocyte morphology in glomerulonephritis.

The differentiation between glomerular and non-glomerular haematuria by phase-contrast microscopy has proved to be a useful tool in the diagnosis of glomerulonephritis. In an attempt to evaluate the effect of marked diuresis on the altered red cell morphology in patients with biopsy proven glomerulonephritis, urinary sediments were examined following water or furosemide-induced diuresis. In both diuretic states urine flow increased, urine osmolality decreased and the percentage of glomerular erythrocytes was significantly reduced in the urinary sediment. These data demonstrate that the alteration in urinary red cells in glomerulonephritis is mainly caused by tubular forces. The diagnostic significance is reduced during increased diuresis and the evaluation of urinary red cell morphology should not be performed.

Adult↗
PubMed1985

Effect of different dialyzers on proteinases and proteinase inhibitors during hemodialysis.

The effect of different membrane materials on plasma levels of granulocyte elastase, 'unspecific' proteolytic (azocasein-hydrolyzing) activity, and activity and concentration of the main plasma proteinase inhibitors alpha 1-proteinase inhibitor (alpha 1PI) and alpha 2-macroglobulin during hemodialysis was investigated. Cuprophan (679.6 +/- 80.0 ng/ml) and polymethyl methacrylate (873.0 +/- 20.6 ng/ml) membranes caused a significantly higher maximal increase of plasma levels of granulocyte elastase-alpha 1-proteinase inhibitor (E-alpha 1PI) complex compared with polyacrylonitrile (395.3 +/- 56.0 ng/ml) or polysulfone (295.2 +/- 41.3 ng/ml) membranes (healthy subject 70.3 +/- 4.4 ng/ml). The activity of alpha 1PI increased significantly during hemodialysis using polyacrylonitrile (+36%) or polysulfone (+29%) membranes, whereas this increase was less using cuprophan (+6%) or polymethyl methacrylate (+8%) membranes. The reverse effect, however, was observed analyzing alpha 1PI concentrations (cuprophan +33%, polymethyl methacrylate +23%, polyacrylonitrile +12%, polysulfone +7%). 'Unspecific' proteolytic activity and non-trichloroacetic acid-precipitable small molecular weight plasma protein fraction decreased significantly during hemodialysis in the presence of all four membranes. We conclude that neutral granulocyte proteinases can be released during hemodialysis independent of the change of white blood cells during the 1st h of dialysis therapy.

Acrylic Resins↗
PubMed1985

Carbohydrate metabolism in potassium-depleted rats.

Carbohydrate metabolism was examined in different organs of rats with dietary potassium deprivation for 4 weeks. Thereafter, a 24- or 48-hour starvation period caused a significant decrease of skeletal muscle and liver glycogen content in K+-depleted (KD) rats, whereas kidney glycogen concentration increased and heart glycogen remained unchanged. In contrast, liver glucose concentration was significantly higher in starved KD animals without changes in muscle, heart, and kidney glucose concentrations. Potassium depletion caused a highly significant decrease of plasma and muscle potassium concentrations, metabolic alkalosis, reduced plasma insulin, and increased creatine phosphokinase levels. Blood lactate, pyruvate, and oxoglutarate levels were significantly enhanced in fasted KD rats, whereas blood citrate, beta-hydroxybutyrate, and glucose concentrations were unchanged. Blood acetoacetate level, however, was significantly reduced following potassium depletion. Therefore, beta-hydroxybutyrate/acetoacetate ratio increased significantly, whereas lactate/pyruvate ratio was not influenced. Our results clearly indicate impaired carbohydrate metabolism in potassium-depleted rats.

Acetoacetates↗
PubMed1984

Granulocyte lysosomal factors and plasma elastase in uremia: a potential factor of catabolism.

In uremic intoxication proteolytic activity in plasma and striated muscle is enhanced. To get further insights into the underlying mechanisms the lysosomal factors of polymorphonuclear (PMN) leukocytes and the plasma elastase-alpha 1-proteinase inhibitor complex were investigated in patients with acute and chronic renal failure. Lysosomal activity was evaluated in peripheral blood smears by the lysis of erythrocytes and plasma (halo formation) around each neutrophil induced by 0.25 M NaC1 borate buffer. In about half of the patients with chronic renal insufficiency on dietary treatment lysosomal activity of PMN leukocytes was reduced. The plasma concentration of elastase-alpha 1-proteinase inhibitor complex was normal in most subjects, but increased in three patients with the highest serum creatinine levels (greater than 13 mg/d1). In the patients with acute renal failure (ARF) of various origin (postoperatively, septicemia, pancreatitis, or dye-induced) halo formation was either reduced or absent. The plasma elastase-alpha 1-proteinase inhibitor complex was increased in 5/6 of the patients by a factor of two to four. Also in the patients on regular hemodialysis treatment halo formation of PMN leukocytes was substantially reduced, whereas the plasma levels of elastase-alpha 1-proteinase inhibitor complex was slightly increased. The finding of reduced lysosomal activity of PMN neutrophils in uremia may be partly due to an enhanced release of neutral proteinases into the circulation as indicated by the elevated plasma levels of elastase-alpha 1-proteinase inhibitor complex in some patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Kidney Injury↗
PubMedDate not supplied

Iron management in renal failure patients--how do we achieve the best results?

The majority of patients with renal insufficiency suffer from a normochromic, normocytic anaemia. This renal anaemia affects the quality of life of these patients and reduces their chance of survival. Despite the availability of recombinant human erythropoetin for the treatment of renal anaemia, many patients do not achieve the target haemoglobin concentration of more than 11 g/dl. A major factor contributing to suboptimal correction of renal anaemia and reduced responsiveness to epoetin is a lack of iron availability to the stimulated erythropoesis.Thus, forthe majority of patients with renal insufficiency intravenous iron therapy will be the treatment of choice to replete and maintain adequate iron stores.

Anemia, Iron-Deficiency↗
PubMedDate not supplied

Influence of dialysis procedure, membrane surface and membrane material on iopromide elimination in patients with reduced kidney function.

Haemodialysis for the elimination of contrast medium in patients with advanced renal failure is a common procedure. Even though sufficient elimination with the use of regular low-flux membranes is documented, large differences in results have been reported in prior investigations. We, therefore, compared Cuprophan and polysulfone dialysers with different surface areas to haemofiltration with different amounts of substitution fluid in 40 patients with compromised renal function after coronary angiography. Plasma iodine concentrations were measured by fluorescent excitation analysis. At constant blood flow rates of 200 ml/min, Cuprophan membranes with 1. 3 m(2) surface area had a clearance rate of 87 ml/min, whereas polysulfone membranes of comparable size displayed a significantly higher clearance rate of 147 ml/min. Polysulfone membranes with 1.8 m(2) surface area showed a small but insignificant increase in the iodine clearance (162 ml/min), while Cuprophan membranes displayed an increase in clearance rates (121 ml/min). Additional ultrafiltration led to a further increase in the plasma clearance of both membranes and reduced urinary iodine excretion. Haemofiltration was comparable to haemodialysis in terms of efficacy and thus represents an alternative method. Clearance of iopromide during haemodialysis with polysulfone membranes is higher than with Cuprophan membranes. Elimination rates can be further increased by additional ultrafiltration. Haemofiltration is comparable to haemodialysis regarding contrast medium elimination.

Biocompatible Materials↗