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Biomedical subjects

W Petek

Publications and source records attributed to W Petek.

At least 37 records · Page 2Linked to original sources
PubMed1989

Relationship between generation and plasma concentration of anorganic phosphorus. In vivo studies on dialysis patients and in vitro studies on erythrocytes.

The plasma concentration of inorganic phosphorus (Pi) was determined before, during and after hemodialysis in 28 patients with chronic renal failure. Pi plasma concentration decreased rapidly when hemodialysis was started but did not fall below normal levels during continued dialysis. These changes of Pi concentration were fitted to a model of Pi kinetics in which Pi delivery to plasma is a nonlinear function of the extracellular Pi concentration. In separate in vitro studies, erythrocytes from six subjects with normal renal function and from 14 patients with chronic renal failure were incubated in homologous plasma with various amounts of Pi added. All other factors known to affect the Pi shift between intra- and extracellular fluid compartments (pH, calcium concentration) were kept constant. The relation between Pi concentration in plasma used for incubation and in red cells after 1h incubation suggested a mechanism in which a high plasma concentration results in movement of Pi into red cells where Pi is stored most probably in glucose esters. At low Pi plasma concentration Pi is delivered to plasma at a rate which cannot be explained solely by passive movement of intracellular Pi to plasma but requires additional generation from intracellular storage forms. The generation and delivery of Pi in patients and in their erythrocytes indicate a simple cell-mediated Pi homeostasis counter-acting abnormal fluctuations of plasma Pi.

Adolescent↗
PubMed1989

[Permeability of the alveolocapillary membrane during unilateral lung lavage. An experimental study].

Experimental unilateral continuous lung lavage in a nonregenerating system containing 3000 ml isotonic crystalloid was performed in 12 pigs to determine the permeability of the alveolocapillary membrane under these conditions. The maximum time of lavage was 270 min. The concentrations of ions in both serum and fluid were determined at defined intervals. Exponential functions adjusted to the electrolyte changes in the fluid suggest different types of kinetics: sodium and urea adapted rapidly to serum concentrations. The half-time of the exponential function was short, the permeability constant high. Calcium, phosphate, and creatinine increased significantly, the permeability constant being lower than for urea. Potassium showed a linear increase, possibly due to influx from intracellular compartments. Total protein and albumin increased only initially, levelling far below the serum values. The low permeability constants of protein and albumin indicate an almost total lack of permeation, the initial increase possibly being due to washout of the epithelial lining fluid compartment. There was only a minimal loss of lavage fluid into the organism.

Animals↗
PubMed1988

Pulmonary exchange of solutes during experimental lung lavage in pigs.

Unilateral continuous lung lavage in a nonregenerating system (3,000 ml isotonic cristalloid) was done in 12 pigs for 270 min. The concentration of substances in serum and fluid was measured. Half-time (t1/2) of exchange and permeability constants (P) were determined. In the fluid Na+ decreased significantly (t1/2 = 107 min, P = 7.8 x 10(-7]. Urea increased significantly, reaching serum level after 270 min (t1/2 = 109.1 min, P = 6.18 x 10(-6]. Ca2+ (t1/2 = 36.7 min, P = 4.1 x 10(-7] PO4 = (t1/2 = 173.3 min, P = 1.1 x 10(-7], and creatinine (t1/2 = 55.2 min, P = 6.2 x 10(-7] also increased markedly but did not reach serum level. The adjustment to serum concentration may be prevented by interaction between diffusion, active transport or Donnan's equilibria. K+ increased almost linearly, documented by the long half-time (t1/2 = 7,835.2 min, P = 7.7 x 10(-7] and did not reach serum level. The calculated limit value was higher than the serum level. Active transport systems or influx of K+ from cellular compartments rather than from the serum might be involved in its linear kinetics. Total protein (t1/2 = 61.5 min, P = 2.06 x 10(-9] and albumin (t1/2 = 58.8 min, P = 1.7 x 10(-9] increased initially but levelled far below the serum value. The low P indicates a lack of significant permeation. Initial increase may be due to washout of the epithelial lining fluid compartment. There was minimal transfer of lavage fluid into the organism (10-20 ml/30 min). Serum concentrations were not affected by the lavage.

Animals↗
PubMed1985

Phosphorus kinetics during haemodialysis and haemofiltration.

Phosphorus excretion during haemodialysis positively correlates with the plasma inorganic phosphorus (Pi) concentration and the dialyser Pi clearance. Therefore, by using highly efficient dialysers or haemofilters, disciplined patients may achieve a well regulated P-balance. The plasma Pi concentration time curve during haemodialysis or haemofiltration must be seen as the result of passive diffusion combined with an active mobilisation of Pi from a rapidly exchangeable P-pool. The plasma Pi concentration hardly falls below the normal range in dialysis patients, regardless of the quantity of Pi removed by haemodialysis or haemofiltration. The stability of plasma Pi demonstrates the existence of a mechanism for phosphate regulation in body fluids, independent of the calcium homeostasis.

Blood↗
PubMed1982

Neurophysiological findings and serum aluminium in dialysis encephalopathy.

64 patients on hemodialysis were investigated. The mean duration of dialysis was 43 months. In all the patients, serum aluminium levels, systolic blood pressure (averaged over a period of 6 weeks) and the EEG were investigated. Psychological testing to assess the level of intelligence (IQ) was also performed. The serum aluminium levels have been assayed by flameless atomic absorption (Perkin-Elmer atomic absorption spectrophotometer model 420). In 6 patients, the diagnosis of dementia was made on the basis of psychological testing and clinical observations. The demented patients showed significantly (p less than 0.01) higher aluminium levels (mean 409 microgram/l, SD 235) than the 58 non-demented patients (mean 189 microgram/l, SD 152), whereas the age of the patients, duration of dialysis and blood pressure were the same in both groups. The EEG was abnormal in all 6 demented patients. Only in 23 of the 58 non-demented patients was the EEG pathological (p less than 0.05). A significant correlation was found between serum aluminium levels and the EEG data with regard to bilateral slow waves, focal slow waves and epileptic potentials (p less than 0.05). The EEG, age of the patients, duration of dialysis and blood pressure showed no correlation. Electromyography, nerve conduction velocity and latency showed no correlation with aluminium levels or dementia. It can be concluded from our findings that in dialyzed patients there is a correlation between serum aluminium levels and the appearance of dementia and EEG changes.

Aluminum↗
PubMed1981

[The importance of aluminiun in dialyseencephalopathie (author's transl)].

64 patient on chronic haemodialysis were investigated. The duration of the dialysis was 44 months; the mean age of patients was 41 years. In 6 patients a diagnosis of Dementia was made in addition to apraxia, dysarthria and anarthria. 5 of the patients died. All the demented patients showed an abnormal EEG and 4 had atrophy in the computertomogram. The plasma aluminium levels were significantly raised (409 microgram/l) in the demented group as compared to the non-demented dialysis patients (189 microgram/l).

Adult↗
PubMed1980

Lupus anticoagulant after measles.

A 2 2/12 years old boy developed a "lupus anticoagulant" after measles. Fibrinogen concentration and activity of factors II, V, VII, VIII, IX, X, XI and XII were normal, but partial thromboplastin time and thromboplastin time were prolonged. Thrombin time was within the normal range. Mixing normal plasma with the patient's plasma immediately prolonged the partial thromboplastin time, and incubation of the sample did not increase the inhibition. The immunglobulin fraction prepared from the patient's plasma on DEAE-sephacel also prolonged the partial thromboplastin time in cross mixing experiments. The thrombocyte count and thrombocyte functions were normal. In spite of the pathological partial thromboplastin and thromboplastin times, surgery was performed without excessive bleeding during the operation and without delayed wound healing.

Blood Coagulation Disorders↗
PubMed1980

[The natural history of dialysis encephalopathy (author's transl)].

18 data with etiopathogenetic relations to the dialysis encephalopathy, such as plasma aluminum levels, parameters of azotemia and parathyroid function, blood pressure, IQ, and EEG-findings, were compared between 5 patients suffering with encephalopathy and 54 dialysis-patients without neurological symptoms. The investigations, including statistical computations (variance analysis, multiple linear regression, multivariate analysis) elicited the following results: 1. All patients suffering from encephalopathy showed higher plasma aluminum concentrations (505 +/- 58 microgram/L : 228.9 +/- 213 microgram/L, p = greater than 0.01), higher serum calcium levels (2.48 +/- 0.15 mmol/L : 2.35 +/- 0.11 mmol/L, p = less than 0.001), higher rates of osteopathy and abnormal EEG's (5 of 5 : 7 in 41 patients). 2. Age, duration of dialysis treatment, quality of dialysis treatment, blood pressure, did not show any pathogenetic influence. 3. Hyperaluminemia was caused by the oral administration of aluminum hydroxide. After reduction of the daily dose from originally 6.18 +/- 3.24 gm to 1.52 +/- 0.45 gm, the plasma aluminum levels decreased to 54.05 +/- 34.59 microgram/L without any adverse effects on the serum phosphate levels. The results suggest that dialysis-patients need less AI-OH than is usually indicated. 4. Encephalopathy did not occur after normalisation of plasma aluminum levels. 5. With respect to the aluminum toxicity in dialysis-patients, dialysis encephalopathy should not be classified as a complication of multifactorial etiology. Only hyperparathyroidism seems to be an additional risk factor.

Adult↗
PubMed1979

Immunologic studies of prothrombin in newborns.

Prothrombin of newborns was investigated by means of the quantitative immunoelectrophoresis and the two-dimensional immunoelectrophoresis. The plasma of 10 of 24 healthy term newborns and of 5 preterm infants taken immediately after birth showed one prothrombin precipitate in the alpha-2-beta-globulin position when a buffer containing 25 mM calcium lactate was used. No differences in the mobility and form of the precipitate could be observed as compared to healthy adults. The plasma of the other 14 term newborns and one small-for-date infant showed two precipitates, one in the alpha-2-beta-globulin position and a second in the alpha-1-globulin position. Twenty-four hr after the injection of vitamin K, the precipitate in alpha-1-globulin position was no longer evident. When a buffer without calcium was used in the two-dimensional immunoelectrophoresis, only one precipitate in the alpha-1-globulin position was found in all newborns. In the quantitative immunologic determination, the prothrombin was found to be decreased as compared to that of adults. The quantitative immunologic determination and the activity assay gave equal results in those infants who had only one precipitate in the two dimensional immunoelectrophoresis. In those newborns, who had two precipitates, the quantitative immunologic determination gave higher results than the measurement of the activity assay. From this study, no evidence of differences between the prothrombin of newborns and that of adults could be derived. Vitamin K deficiency, as judged from the appearance of a second peak in alpha-1-globulin position in the two dimensional immunoelectrophoresis was a frequent findings in term newborns, even on the 1st day of life.

Adult↗
PubMed1979

[Evidence of type-specific microheterogeneity of thyroxine-binding globulin by isoelectric focusing (author's transl)].

A rapid method for the isolation of the thyroxine-binding globulin from only 150 ml plasma is described. The preparation of a high-activity thyroxine-sepharose is essential; this contained L-thyroxine bound exclusively by covalent linkage. Furthermore, the elution of the protein was performed under specifically hydrophobic conditions. Using isoelectric focusing on 15 individual preparations of thyroxine-binding globulin, and densitometric analysis of the polyacrylamide gels, it was possible to show three protein bands in different proportions according to the individual. Three distribution-types were found in the tested volunteers. The results of this investigation show that these types are individual-specific, whereas there are no apparent sex-specific differences.

Female↗
PubMed1978

Serum haptoglobulin changes in patients with severe isolated head injury.

From a series of 74 patients with severe head injuries and massive brain lesions, we measured the changes in haptoglobulin in 33 cases. On average, the globulin was, after a short drop in the first two days, increased about three times towards the seventh day, and was still above normal after ten days. Seen together with the total alpha-2-globulin increase after head injury this rise seems mainly to be caused by the haptoglobulin changes. Haptoglobulin was found to be a good indicator of the extent of brain tissue damage. It cannot on its own be used for prediction of survival chances.

Adult↗
PubMed1978

[Hemostasis in hereditary hemorrhagic telangiectasia (author's transl)].

The investigation of a girl aged 8 with hereditary hemorrhagic telangiectasia showed an abnormality of primary hemostasis. The bleeding time was at the upper end of normal and platelet adhesiveness was decreased to a variable extent. Platelet life span was shortened, presumably due to the telangiectatic lesions typical of this disease. Platelet aggregation and ADP-content were normal as was the plasma coagulation system.

Blood Coagulation↗