Which Organic Acids does Hemofiltrate Contain in the Presence of Acute Renal Failure?

It is not generally possible to measure most organic acids in the serum of critically ill patients, due to rapid metabolism and methodological problems. Only the regular measurement of lactic acid and the arterial ketone body ratio (acetoacetate/beta-hydroxybutyrate, AKBR) have been introduced in clinical practice, but these parameters can represent only a part of the disturbed metabolism. In pediatric patients, a chromatographical urine analysis has been established for detection of inborn errors of metabolism, which allows the determination of more than 50 organic acids simultaneously (gas chromatographic (GC) analysis in combination with mass spectrometry (MS)]. In continuous treatment of acute renal failure, hemofiltrate is always available, but it contains only low protein concentrations and after the filtration process, metabolism is rapidly stopped. The sieving coefficient of lactic acid is nearly one in hemofiltration. The aim of our study was to compare results of the regular and CG/MS methods in blood and hemofiltrate for lactic acid, and to find other organic acids of possible clinical importance. We investigated serum (lactic acid) and hemofiltrate of 40 critically ill patitens, similar to the urine analysis method for infants. All patients suffered from acute renal failure and were treated by continuous veno-venous hemofiltration (CVVH). The conditions of treatment were standardized (spontaneous ultrafiltration in the first hour), and the material (blood/hemofiltrate) was taken one hour after the beginning of extracorporeal circulation. Statistical methods included correlation analysis, nonparametric ANOVA with Wilcoxon scores (ranks of data), and stepwise discriminant analysis. Regular and GC/MS methods in hemofiltrate showed a good correlation for lactic acid. The best correlation with lactic acid was found for 4-hydroxy-phenyllactic acid (n=20, r=0.866), 2-hydroxy-valeric acid (n=22, r=0.7491) and 2-hydroxybutyric acid (n=32, r=0.5148). Age, sex, diagnosis, and APACHE II score play a subordinate role, but the presence of glyceric and citric acid possibly have prognostic importance [nonparimetric ANOVA with Wilcoxon scores (ranks of data)], as does the combination of 3-hydroxypropionic acid, glyceric acid, and threonic-acid-4-lacton (stepwise discriminant analysis). It can be concluded that in acute renal failure, the measurement of lactic acid and AKBR can reflect only a small part of disturbed metabolism. Hemofiltrate can be a useful medium in describing metabolic processes in critically ill patients with acute renal failure. Some inherited metabolic diseases in infants (phenylketonuria, maple syrup disease) and ketoacidosis show similar metabolic modifications.

The Measurement of Cytokine Production Capacity during Dialysis - a New Dynamic Method for the Evaluation of Biocompatibility?

The activation of monocytes and other immunocompetent cells during hemodialysis can be attributed to their contact with immunogenic structures such as membranes, blood lines, and endotoxins. The simple measurement of cytokines in blood cannot completely describe the whole dimension of this event. Stimulation of monocytes and other immunocompetent cells in whole blood with lipopolysaccharides (LPS) for IL-6 and phytohemagglutinine (PHA) for TNF at the start and end of dialysis may make it possible to better analyze cellular response during dialysis. Ten healthy volunteers and 10 patients suffering from chronic renal failure were tested with the commercial whole-blood stimulation assays “Dynamix”-IL-6-DIA and -TNF-alpha-DIA (Biosource Diagnostics, Ratingen, Germany). Then 24 patients undergoing hemodialysis with hemophane (n=12) and polyamide (n=12) membranes were examined before and after dialysis treatment. The unpaired Wilcoxon t- test was used for statistical analysis. Healthy volunteers and patients with chronic renal failure showed no statistical differences in concentrations of TNF-alpha and IL-6 before or after whole blood stimulation (WBS). In comparison to patients with chronic renal failure, pre-WBS concentrations of both cytokines (p<0.034) were increased in patients of each membrane group before dialysis. After whole blood stimulation, no differences were observed. At the end of dialysis treatment, the pre- and post-WBS IL-6 values were both significantly higher in the hemophane group (p=0.049 and p=0.0038, respectively) TNF-alpha concentrations were unchanged. No significant differences in the polyamide group were found between the start and end of treatment for either cytokine. A comparison of these membrane groups showed that only the pre-WBS IL-6 concentration in the hemophane group was elevated (p=0.022) after dialysis. In conclusion, the presence of uremia alone could not influence the cytokine production and release capacity. In our patients, dialysis elevated pre-WBS concentrations of TNF-alpha and IL-6, and increased IL-6 release from immunocompetent cells after whole blood stimulation in the hemophane group. The use of polyamide membranes decreased the action of monocytes and other immunocompetent cells, but could not completely prevent this phenomenon. The whole blood stimulation assays for measurement of TNF-alpha and IL-6 may represent a new, dynamic method for evaluating biocompatibility.

Which Amino-Acids do Serum and Hemofiltrate of Critically Ill Patients with Acute Renal Failure Contain?

The removal of amino acids during continuous renal replacement therapies induces clinical problems. Previous studies on animals have shown nephroprotective (glycine, alanine) or negative effects (lysine) on renal function in occurrence of acute renal failure. Disturbed metabolism in acute renal failure needs adequate parenteral nutrition. On the other hand, experience with continuous renal replacement therapies of metabolic crises in inborn errors of metabolism indicate a good control of disturbed amino acid metabolism. The aim of our study was to find amino acids, that might play an important role in the pathogenesis, prognosis and detection of acute renal failure and severe illness, so far only estimated by lactic acid. Thirty-three probes (serum and hemofiltrate) were taken from patients, suffering with acute renal failure caused by septic shock, severe pancreatitis and hepatorenal syndrome, one hour after the beginning of extracorporal circulation, the conditions of treatment were standardized. The material was deproteinized and studied by the amino acid analyzer LBK 4251 Apha Plus (Pharmacia, Stockholm, Sweden), while the lactic acid concentration was determined in a standard laboratory. Proline, glycine, alanine, methionine and histidine showed a close relationship to the lactic acid levels, but these amino acids were an essential part of parenteral nutrition. A statistical relationship was also established in (amino acids with amide groups) asparagine, glutamine, citrulline, cystathionine and phosphoethanolamine. The mean values of most of the amino acids were higher than normal, but standard deviations were increased. The presence of these amino acids in hemofiltrate and the good sieving coefficients could mean that the better prognosis of critically ill patients in continuous renal replacement therapies may also be due to continuous control of amino acid levels (especially with amide groups).

On-line production of ultrapure substitution fluid reduces TNF-alpha- and IL-6 release in patients on hemodiafiltration therapy

On-line hemodiafiltration (HDF) has been introduced into clinical practice in the last few years. The most important technical and regulatory challenges were the safety and microbiological quality of ultrafiltrated substitution/replacement fluid. The application of ultrafilters in a different technical arrangement in the fluid path based on polysulfone or polyamide membranes should prevent patient contact with endotoxins and other pyrogenic or bacteria-derived substances. After resolving these problems and providing clinically safe and technically robust product solutions, increasing numbers of patients have been treated, especially those with severe clinical conditions, e.g., diabetes, hypo- or hypertension. The benefit for patients was brought about by the increase of substitution rate in hemodiafiltration and enhancing convective mass transfer. The impact of highly convective therapy modes on the state of immunomodulation towards the syndrome of microinflammation has not been investigated in a systematic prospective manner. In this study, 8 patients undergoing bag-HDF treatment with lactate buffered solution were investigated before on-line HDF treatment with commercially available whole blood stimulation assays testing for TNF-alpha and IL-6 release. Both assays are based on phytohemagglutinine (for TNF) and lipo-polysaccharide stimulation (for IL-6). Thereafter the patients were switched to on-line production of substitution fluid. After a wash-out period of 2 sessions the whole blood stimulation assays were applied to the same patients. The Wilcoxon test (for paired analysis) was done, revealing a statistically significant lower release of proinflammtory cytokines from patients' blood upon stimulation with PHA or LPS. The reduction of IL-6 and TNF concentration and release capacity in whole blood may be attributed to the use of high quality ultrapure substitution fluid and dialysate in on-line treatment instead of lactate buffer bag solution. These results indicate that not only an increase of convective mass transfer by higher volume exchange, but also a decrease in unspecific activation of immunocompetent cells may have advantages for HDF-treated patients.

Proteinuria and plasma total homocysteine levels in chronic renal disease patients with a normal range serum creatinine: critical impact of true glomerular filtration rate

Conflicting data have been reported concerning the independent association between proteinuria and plasma total homocysteine (tHcy) levels, particularly among chronic renal disease (CRD) patients with a normal range serum creatinine. Studies of this potential relationship have been limited by failure to assess true GFR, failure to assess proteinuria in a quantitative manner, or arbitrary restriction of the range of proteinuria examined. We examined the potential independent relationship between plasma tHcy levels and a wide range of quantitatively determined proteinuria (i.e., 0.000-8.340 g/day), among 109 CRD patients with a normal range serum creatinine (range; 0.8-1.5 mg/dl; median=1.2 mg/dl). Glomerular filtration rate (GFR) was directly assessed by iohexol clearance, and plasma status of folate, pyridoxal 5'-phosphate, and B12, along with serum albumin, were also determined. Linear modeling with ANCOVA revealed that proteinuria was not independently associated with tHcy levels (partial R=0.127; P=0.201), after adjustment for potential confounding by GFR (partial R=0.408; P<0.001), age, sex, plasma B-vitamin status, and serum albumin. Moreover, descending across quartiles (Q) [from Q4 to Q1] of GFR, ANCOVA-adjusted (i.e., for age, sex, and folate status) geometric mean tHcy levels (micromol/l) were significantly increased: tHcy Q4 GFR=9.6; tHcy Q3 GFR=10.5; tHcy Q2 GFR=11.9; tHcy Q4 GFR=14.5; P<0.001 for overall Q difference. We conclude that across a broad spectrum of quantitatively determined proteinuria, after adjustment for true GFR, in particular, there is no independent relationship between proteinuria and tHcy levels among CRD patients with a normal range serum creatinine.

Chronic renal transplantation: a model for the hyperhomocysteinemia of renal insufficiency

Renal transplant recipients (RTR) are considered representative of patients with chronic renal insufficiency (CRI) in general with respect to both reduced, progressively declining renal function, and increased risk for cardiovascular disease (CVD). In accord with this argument, we hypothesized that total (t) plasma concentrations of the putatively atherothrombotic amino acid homocysteine (Hcy) would be equivalent in RTR and CRI patients with comparable renal function. We determined plasma tHcy, folate, pyridoxal 5'-phosphate, and B12 concentrations, in addition to serum creatinine and albumin concentrations, in 86 chronic, stable RTR, and 238 patients with CRI. Within comparable ranges of serum creatinine (i.e. RTR=0.6-4.2 mg/dl; CRI=0.7-4.1 mg/dl), tHcy concentrations did not differ between the two groups (RTR=15.0 micromol/l; CRI=14.9 micromol/l, P=0.899). ANCOVA revealed that renal function, gauged as a simple creatinine measurement, was the major independent determinant of plasma tHcy concentrations, accounting for approximately 80-90% of the total variability in tHcy predicted by the full model (i.e. full model R(2)) containing, in addition to creatinine, the seven other potential explanatory variables. If controlled trials confirm that tHcy-lowering treatment reduces CVD events rates in RTR, these results should be applicable to CRI patients in general.

The measurement of cytokine production capacity during dialysis--a new dynamic method for the evaluation of biocompatibility?

The activation of monocytes and other immunocompetent cells during hemodialysis can be attributed to their contact with immunogenic structures such as membranes, blood lines, and endotoxins. The simple measurement of cytokines in blood cannot completely describe the whole dimension of this event. Stimulation of monocytes and other immunocompetent cells in whole blood with lipopolysaccharides (LPS) for IL-6 and phytohemagglutinine (PHA) for TNF at the start and end of dialysis may make it possible to better analyze cellular response during dialysis. Ten healthy volunteers and 10 patients suffering from chronic renal failure were tested with the commercial whole-blood stimulation assays "Dynamix"-IL-6-DIA and -TNF-alpha-DIA (Biosource Diagnostics, Ratingen, Germany). Then 24 patients undergoing hemodialysis with hemophane (n=12) and polyamide (n=12) membranes were examined before and after dialysis treatment. The unpaired Wilcoxon t- test was used for statistical analysis. Healthy volunteers and patients with chronic renal failure showed no statistical differences in concentrations of TNF-alpha and IL-6 before or after whole blood stimulation (WBS). In comparison to patients with chronic renal failure, pre-WBS concentrations of both cytokines (p<0.034) were increased in patients of each membrane group before dialysis. After whole blood stimulation, no differences were observed. At the end of dialysis treatment, the pre- and post-WBS IL-6 values were both significantly higher in the hemophane group (p=0.049 and p=0.0038, respectively) TNF-alpha concentrations were unchanged. No significant differences in the polyamide group were found between the start and end of treatment for either cytokine. A comparison of these membrane groups showed that only the pre-WBS IL-6 concentration in the hemophane group was elevated (p=0.022) after dialysis. In conclusion, the presence of uremia alone could not influence the cytokine production and release capacity. In our patients, dialysis elevated pre-WBS concentrations of TNF-alpha and IL-6, and increased IL-6 release from immunocompetent cells after whole blood stimulation in the hemophane group. The use of polyamide membranes decreased the action of monocytes and other immunocompetent cells, but could not completely prevent this phenomenon. The whole blood stimulation assays for measurement of TNF-alpha and IL-6 may represent a new, dynamic method for evaluating biocompatibility.

Which organic acids does hemofiltrate contain in the presence of acute renal failure?

It is not generally possible to measure most organic acids in the serum of critically ill patients, due to rapid metabolism and methodological problems. Only the regular measurement of lactic acid and the arterial ketone body ratio (acetoacetate/beta-hydroxybutyrate, AKBR) have been introduced in clinical practice, but these parameters can represent only a part of the disturbed metabolism. In pediatric patients, a chromatographical urine analysis has been established for detection of inborn errors of metabolism, which allows the determination of more than 50 organic acids simultaneously (gas chromatographic (GC) analysis in combination with mass spectrometry (MS)]. In continuous treatment of acute renal failure, hemofiltrate is always available, but it contains only low protein concentrations and after the filtration process, metabolism is rapidly stopped. The sieving coefficient of lactic acid is nearly one in hemofiltration. The aim of our study was to compare results of the regular and CG/MS methods in blood and hemofiltrate for lactic acid, and to find other organic acids of possible clinical importance. We investigated serum (lactic acid) and hemofiltrate of 40 critically ill patitens, similar to the urine analysis method for infants. All patients suffered from acute renal failure and were treated by continuous veno-venous hemofiltration (CVVH). The conditions of treatment were standardized (spontaneous ultrafiltration in the first hour), and the material (blood/hemofiltrate) was taken one hour after the beginning of extracorporeal circulation. Statistical methods included correlation analysis, nonparametric ANOVA with Wilcoxon scores (ranks of data), and stepwise discriminant analysis. Regular and GC/MS methods in hemofiltrate showed a good correlation for lactic acid. The best correlation with lactic acid was found for 4-hydroxy-phenyllactic acid (n=20, r=0.866), 2-hydroxy-valeric acid (n=22, r=0.7491) and 2-hydroxybutyric acid (n=32, r=0.5148). Age, sex, diagnosis, and APACHE II score play a subordinate role, but the presence of glyceric and citric acid possibly have prognostic importance [nonparimetric ANOVA with Wilcoxon scores (ranks of data)], as does the combination of 3-hydroxypropionic acid, glyceric acid, and threonic-acid-4-lacton (stepwise discriminant analysis). It can be concluded that in acute renal failure, the measurement of lactic acid and AKBR can reflect only a small part of disturbed metabolism. Hemofiltrate can be a useful medium in describing metabolic processes in critically ill patients with acute renal failure. Some inherited metabolic diseases in infants (phenylketonuria, maple syrup disease) and ketoacidosis show similar metabolic modifications.

Presence of factor-VII and -XIII activity in ultrafiltrate during hemofiltration

Bleeding complications during renal replacement therapies can be attributed to coagulation system and platelet function alterations in uremia, and the application of heparin in extracorporeal circulation. Small protein losses during hemofiltration are always described, however the high molecular weight of coagulation factors should significantly prevent their removal during hemofiltration. To exclude degradation of coagulation factors under conditions of spontaneous ultrafiltration, the hemofiltrate of 40 patients with acute renal failure (treated with continuous veno-venous hemofiltration, CVVH) was sampled from the filtrate line after 1 h from the beginning of treatment and in 5 patients also after 12 and 24 h. Samples were investigated with human factor deficient plasma (VII, X, XI, XII) from donors with a congenital deficiency and with human plasma depleted of factor V, VIII, IX, and protein S and C. Factor XIII was detected photometrically. Subsequently the presence of factor- XIII and -VII activity was investigated in plasma and hemofiltrate from 16 patients treated with intermittent hemofiltration before (plasma) and after (plasma, hemofiltrate) therapy. These patients also suffered from acute renal failure and needed renal replacement therapies. Quality control was carried out with a buffer solution (<1% activity in the assays according to recommended protocols).

RESULTS

Factor-V, -VIII, -IX, -X, -XI, and -XII activity, and protein C and S could not be detected in the hemofiltrate from continuous hemofiltration. Factor-VII and -XIII activity was present in the hemofiltrate (mean activity in CVVH: 1.93% for factor VII and 6.9% for factor XIII, mean activity in intermittent hemofiltration: <1% for factor-VII and 7.3% for factor-XIII). Three were no significant differences (Student's t-test) in plasma activity before and after intermittent hemofiltration of factor VII (44 vs. 47%, p = 0.39) and factor XIII (44 vs. 52%, p = 0.24). The presence of factor-VII and -XIII activity in the hemofiltrate cannot influence plasma activities in intermittent hemofiltration. Rapid new synthesis and short half-life should neutralize these effects. Elimination of coagulation factor-XIII activity should be excluded by the next generation of highly permeable membranes and on-line hemodiafiltration.

Atypical heparin-induced thrombocytopenia complicated by intracardiac thrombus, effectively treated with ultra-low-dose rt-PA lysis and recombinant hirudin (Lepirudin)

A serious retroperitoneal bleeding occurred in a 56-year-old male patient receiving unfractionated heparin due to multiple pulmonary embolism. After reducing the heparin dose, the patient developed a new pulmonary embolism and a large thrombus in the right atrium. Concomitantly, the platelet count dropped to a value of 29 g/l. Heparin-induced thrombocytopenia (HIT) was confirmed by a functional assay, the heparin-induced platelet activation (HIPA) assay, whereas the results of a platelet factor 4/heparin complex ELISA were repeatedly negative. This indicated that the patient's HIT antibodies were directed towards an antigen other than platelet factor 4/heparin complexes. For treatment of the atrial thrombus, an ultra-low-dose lysis with rt-PA (2 mg/h, intravenously) was administered for a period of 52 h, overlapping with systemic treatment with recombinant hirudin (Lepirudin, Refludan, 0.06-0.14 mg/kg/h intravenously). The aim was to enhance lysis of the thrombus without increasing the haematoma, and at the same time keep the risk of fulminant pulmonary embolism due to thrombus fragmentation as low as possible. The cardiac thrombus disappeared within 48 h, without new signs of pulmonary embolism. Platelet counts normalized within nine days.

Which amino-acids do serum and hemofiltrate of critically ill patients with acute renal failure contain?

The removal of amino acids during continuous renal replacement therapies induces clinical problems. Previous studies on animals have shown nephroprotective (glycine, alanine) or negative effects (lysine) on renal function in occurrence of acute renal failure. Disturbed metabolism in acute renal failure needs adequate parenteral nutrition. On the other hand, experience with continuous renal replacement therapies of metabolic crises in inborn errors of metabolism indicate a good control of disturbed amino acid metabolism. The aim of our study was to find amino acids, that might play an important role in the pathogenesis, prognosis and detection of acute renal failure and severe illness, so far only estimated by lactic acid. Thirty-three probes (serum and hemofiltrate) were taken from patients, suffering with acute renal failure caused by septic shock, severe pancreatitis and hepatorenal syndrome, one hour after the beginning of extracorporal circulation, the conditions of treatment were standardized. The material was deproteinized and studied by the amino acid analyzer LBK 4251 Apha Plus (Pharmacia, Stockholm, Sweden), while the lactic acid concentration was determined in a standard laboratory. Proline, glycine, alanine, methionine and histidine showed a close relationship to the lactic acid levels, but these amino acids were an essential part of parenteral nutrition. A statistical relationship was also established in (amino acids with amide groups) asparagine, glutamine, citrulline, cystathionine and phosphoethanolamine. The mean values of most of the amino acids were higher than normal, but standard deviations were increased. The presence of these amino acids in hemofiltrate and the good sieving coefficients could mean that the better prognosis of critically ill patients in continuous renal replacement therapies may also be due to continuous control of amino acid levels (especially with amide groups).

Prevalence of increased intracellular signal transduction in immortalized lymphoblasts from patients with essential hypertension and normotensive subjects

OBJECTIVE

To determine the prevalence of enhanced signal transduction in immortalized B lymphoblasts from normotensive subjects and patients with essential hypertension.

METHODS

We established Epstein-Barr virus-immortalized lymphoblast cell lines from 26 normotensive and 37 hypertensive subjects. Subsequently, we quantified rises in the cytosolic free Ca2+ concentration, [Ca2+]i, evoked by 0.1 micromol/l platelet-activating factor (PAF) in Fura-2-loaded cells.

RESULTS

PAF-induced [Ca2+]i rises were independent of donor age in cells from normotensive and hypertensive subjects. Baseline values of [Ca2+]i were not significantly different in the two groups. Using the mean + 2SD of the PAF-evoked rises in [Ca2+]i above basal (110 nmol/l) as the upper normal value, we estimate that enhanced [Ca2+]i rises are distinctly more prevalent in hypertensive subjects (27%) than they are in normotensive subjects (4%). Similarly, upon definition of normal values by the 99% confidence interval (75 nmol/l), 19% of cells from normotensive versus 43% from hypertensive subjects display enhanced intracellular signaling.

CONCLUSION

Enhanced intracellular signal transduction could be the primary defect in approximately one-third of the overall population with essential hypertension.

K(+)-permeability in diabetics and nondiabetics with and without renal insufficiency

Looking for causes or consequences of primary hypertension much attention is drawn to the ion transport systems of the cellular membrane. The existence of endogeneous digitalis-like factors, that lower the activity of Na+/K(+)-ATPase and result in a complex change of electrolyte balance of cells are discussed as a reaction of the organism to salt and volume retention. The measurement of passive permeability of erythrocyte membranes for potassium is an easy and useful method for the detection of disturbances of Na+/K(+)-transport, especially for extensive screening investigations. We examined the potassium permeability of erythrocytes in healthy individuals (GR1, n = 48), patients with compensated renal insufficiency (GR2, n = 36) and diabetics (GR3, n = 25) as well as a group of diabetics with renal failure (GR4, n = 47). The relative change of potassium concentration in the whole blood, based on the efflux of potassium during a 4-hour-incubation at 37 degrees C, is defined as a measure for K(+)-permeability. K(+)-concentrations are determined every 60 minutes with ion sensitive electrodes. K(+)-permeability was significantly increased in patients with compensated renal insufficiency compared to the control group and to diabetics. Diabetics differed markedly in their erythrocyte reaction regarding K(+)-permeability. Whereas patients with renal insufficiency show an efflux of potassium during investigation there is a decrease of potassium in plasma in diabetics. The K(+)-permeability results of patients with both diseases are intermediate between the GR2- and GR3 results and are significantly different from the control group. When g-strophanthin is added to inhibit the sodium pump, the differences between the groups are abolished. The decreased K+permeability in diabetics compared to the control group could be explained by the increased supply of energy-rich substrates for the Na+/K(+)-ATPase.

Salt sensitivity and insulin resistance in normotensives

Among hypertensive patients salt sensitivity and insulin resistance are commonly observed together. We investigated if a causal relationship already exists in young normotensive adults. With a standardized dietary regimen we determined salt sensitivity in 35 male volunteers by measuring diastolic blood pressure (24-hours-RR-recording). Insulin resistance was tested using hyperinsulinaemic-euglycaemic-clamp-technique by de Fronzo after a freely chosen diet, after 7 days of salt loading (260 mmol/d) and after 7 days of salt restriction (60 mmol/d). Data from euglycaemic-clamp technique were available from 27 subjects. 18 of them (67%) could be characterized as salt resistant; 9 persons (33%) were salt sensitive. Glucose infusion rate, mean glucose and insulin concentrations were measured in plasma, metabolic clearance rate (MCR) and indices of insulin sensitivity (ISI) were calculated. The results of MCR and ISI show large interindividual variances. There were no differences between the salt sensitive and salt resistant group regarding the mean insulin concentrations and also the mean glucose uptake in the steady state clamp period and also the calculated MCR and ISI. Comparing the periods of different salt intake, there were no differences between salt loading and salt restriction. Whereas salt sensitivity can already be shown in the normotensive state, with this experimental design a changed insulin sensitivity is not detectable. This supports the idea, that insulin resistance is not causally linked with salt sensitivity. It may be a secondary phenomenon of salt induced hypertension.

Low-dose calcitriol prevents the rise in 1,84-iPTH without affecting serum calcium and phosphate in patients with moderate renal failure (prospective placebo-controlled multicentre trial)

BACKGROUND

Higher doses of calcitriol are effective in lowering markedly elevated 1,84 PTH levels of patients with renal secondary hyperparathyroidism. It has not been established, however, whether prophylactic administration of low doses of calcitriol prevents an increase of 1,84 PTH without causing side-effects, i.e. hypercalcaemia, hypercalciuria, or hyperphosphataemia.

STUDY DESIGN

We carried out a placebo-controlled, double-blind prospective multicentre trial over 12 months in 45 patients with mild to moderate renal failure. Criteria for inclusion were S-creatinine 1.4 mg/dl and 1,84 PTH > 6 pmol/l (normal 6). Calcitriol 0.125 microgram/day per os was compared with placebo. The patients received calcium carbonate per os if serum P exceeded 1.7 mmol/l.

RESULTS

Baseline 1,84 iPTH concentrations were not significantly different, i.e. 14.0 pmol/l (6.7-63.3) on placebo vs 16.2 (6.85-82.0) on calcitriol. Intention to treat analysis revealed a significant difference of final 1,84 iPTH, i.e. 27.8 (4.2-68.5) on placebo vs 18.2 (4.45-75.5) on calcitriol. On post-hoc analysis the difference was even more pronounced at S-creatinine concentrations above 3 mg/dl. S-calcium, S-phosphate, and urinary excretion of calcium did not change significantly on either placebo or on calcitriol. There were no episodes of hypercalcaemia or hyperphosphataemia. There was no significant difference of final S-creatinine or change in S-creatinine between placebo and calcitriol. One patient on calcitriol and two on placebo progressed to terminal renal failure. Bone alkaline phosphatase as a non-invasive index of bone metabolism was not decreased to subnormal levels.

CONCLUSION

The results document that a therapeutic window exists in patients with moderate renal failure and elevated of 1,84 iPTH, where low-dose calcitriol (0.125 microgram/day) prevents the increase in 1,84 iPTH without causing side-effects. This observation suggests that the parathyroid is more sensitive to calcitriol than intestine and bone.

Further advances of chronic renal replacement therapy in eastern Germany, 1994 versus 1989

Unlike the other former Soviet-block countries, Eastern Germany/the "GDR", had the opportunity to the re-unification with a highly developed western country, the Federal Republic of (West) Germany in 1990. In order to record the following rapid improvements in renal replacement therapy, we performed our own survey in Eastern Germany--excluding Eastern Berlin--by questionnaire, comparing the years 1989/December, and 1994/December. 112 of the 113 dialysis facilities for adult regular dialysis patients replied to our questionnaire (99%). From 1989 to 1994, the number of dialysis centers increased from 53 to 113 (-->213%), reaching 7.9 centres p.m.p. Of these facilities, 29% were hospital centers, 48% were private dialysis units, and 23% were run by nonprofit dialysis organizations. The number of dialysis stations increased from 602 to 1,719 (-->286%), i.e. 120 stations p.m.p. The number of patients in regular dialysis treatment rose from 2,127 to 5,335 (-->251%), that means a prevalence of 373 patients p.m.p. In 1989, 67 new patients (p.m.p.) had been accepted for maintenance treatment (incidence), in contrast to 130 new patients p.m.p. in 1994 (-->194%), now under the conditions of unlimited accessibility to dialysis treatment. Questions referring to this point--the incidence of new patients--were only asked in Thüringen (2.5 mio. inhabitants). Alternative treatment modalities became feasible under the new conditions in Eastern Germany. In contrast to 99% hemodialysis patients in December 1989, at the end of 1994 92.8% of the patients were treated by hemodialysis, 2.0% by hemofiltration, and 5.2% by peritoneal dialysis, predominantly CAPD.(ABSTRACT TRUNCATED AT 250 WORDS)

[A concentration measuring error-induced calculation error in determining uric acid clearance in dialysis: a simulation study]

Three calculation methods to estimation of the total clearance of dialysis patients are evaluated. The basis of calculation are concentration values of urea in blood versus dialysate. The variation coefficient of the measurement errors is 5 percent. The error formation in three estimation formulas is examined. The formula [formula: see text] is most suitable, if as evaluation criteria the variation coefficient of the estimation error are used. The parameters like dialysate flow, blood flow, ultrafiltration rate and dialysate volume are of relative value.

[Serotonin uptake of thrombocytes as a measure of thrombogenicity of adsorbents]

Serotonin intake into platelets is an active carrier-mediated metabolic achievement. This uptake may be reduced by unphysiological irritation on platelet membrane. Therefore, it is suitable for judgement of thrombogenicity of biomaterials. The 14C serotonin intake after blood contact with various adsorbents was investigated: Haemoresin (GDR), Adsorba 300 C (USSR) and syrendivinylbenzencopolymer FK 1621 (GDR). Only by the latter the serotonin intake was significantly reduced with 72.5 +/- 2.0% in comparison with siliconized glas (84.0 +/- 1.5%; p less than 0.001). Precision and analytical sensitivity of the method are high with a variation coefficient of 1.5 to 3.5%.

[HLA antigen frequencies in patients with autosomal dominant polycystic kidney degeneration]

20 non-related patients suffering from autosomal dominantly polycystic renal disease were HLA-A, -B, -C and -DR typified and the HLA frequencies were compared with the normal population. Tissue typing was performed using the lymphocytotoxicity test using 180 well-characterized test sera. In contrast to the literature no significant differences were found. However, the value of erythrocytic phosphoglycolate-phosphatase-phenotyping should be checked in the genetic control and consultation.

[Preventive use of nitrofurantoin in recurrent urinary tract infections]

51 patients suffering from chronic urinary tract infection were treated from 6 to 12 months with a single evening dose of 100 mg nitrofurantoin. The frequency of re-infection in the treatment period was compared with the same period before onset of therapy. The number of such re-infections was reduced significantly. Side effects of this therapy were substantial lower than after a three-times application per day. Gastrointestinal symptoms could be reduced in more than 50% of the cases by a combined therapy of 100 mg nitrofurantoin and 20 mg vitamin B6.

Tubular dysfunctions in the diagnostic differentiation of glomerulonephritis, pyelonephritis, and diabetic nephropathy

Concentration and acidification capability was tested in 41 patients with chronic pyelonephritis (PN), 14 patients with chronic glomerulonephritis (GN), 16 patients with diabetic nephropathy (DNP) and 12 healthy controls. Significant differences appeared between PN and GN, PN and DNP comparing a quotient between percent of normal osmolarity and percent of normal creatinine clearance. Similar results were obtained using a quotient creatinine clearance/ammonia excretion, which enabled the differentiation of PN from the other groups. The tubular functions of concentration and ammonia excretion in relation to creatinine are clinically useful in the differentiation of pyelonephritis from glomerular kidney diseases.

[Measurement of activated whole blood coagulation as a control parameter for heparin dosage in hemodialysis]

A precise dosage of heparin is necessary especially in acute dialysis, but also in chronic dialysis. This can be checked by measuring the partial thromboplastin time, the thrombin time, the coagulation time according to Lee-White or, recently, by automatic measurement of activated whole-blood coagulation. For the latter only 0.5 ml of whole blood is necessary. In a total of 44 examinations the activated whole-blood coagulation time was shown to be well reproducible. In the 40 patients examined there was considerable variation in the sensitivity to and the elimination rate of heparin, which indicates the necessity of individual heparin dosage. Measuring the activated whole-blood coagulation time proved to be suitable for classifying the patients.

[Results of sonographic kidney diagnosis]

In a prospective study of the examination of the accuracy of the ultrasound tomography in the renal diagnostics the kidneys of 361 patients could be demonstrated as at 100% sufficiently to be judged. Tumours, congestion kidneys, cystic kidneys/renal cysts and cirrhoses of the kidney were diagnosed with an efficiency of 0.92-0.96-0.97-1.0. The sensitivity was in the same order 0.90-0.96-0.99-1.0 and the specificity 0.94-1.0-0.95-1.0. Insufficient results were obtained by the sonographic search for renal calculi. As non-invasive and rapid method of diagnostics the sonography in a valuable way contributes to the differentiation of the symptom "quiescent kidney" and oligo-anuria.

[Pseudo-lupus erythematosus syndrome and interstitial nephritis]

First in 1972 under the preliminary term pseudo-lupus-erythematodes-syndrome a clinical picture was represented which clinically resembles the lupus erythematodes disseminatus and which is characterized by the proof of antimitochondrial antibodies and the lack of antinuclear factors. We report on a female patient with this syndrome and interstitial concomitant nephritis. Possible causal factors, clinical picture, typical laboratory findings, therapy and prognosis are discussed with the help of the casuistics.

[Simultaneous diagnostic studies of bacteriuria as related to method of urine collection]

In a direct comparative series were compared 204 functional, catheter, and mid-stream urines which were got simultaneously in patients with chronic pyelonephritis. In suprapubic vesical puncture 113 had a sterile urine, 91 showed a bacteriuria. After catheterisation 103 specimens were still sterile and 101 were bacterially infected. Of the mid-stream urines only 90 proved sterile, and 114 times pathogenic agents could be proved. While in males mid-stream urines achieved good results, in females a contamination was pretty frequent. Repeated investigations, estimation of the number of germs, and optimum taking essentially improve evidence. Though in females by means of catheterisation better bacteriological results may be achieved, in rare cases there is the danger of the invasion of germs. A clear judgment is possible, using the suprapubic vesical puncture.

[Relationships between the value of combined PAH-inulin clearance, the kidney-cortex index as well as between additional radiographic findings in chronic pyelonephritis]

In 85 patients with ascertained chronic pyelonephritis the relations between the measured values of the combined PAH-inulin-clearance, the index of the adrenal cortex and other radiological findings were investigated. Here the determination of the cortex of the adrenal cortex resulted in a better correlation with the sizes clarification values than the calculation of the size of the kidney. By variance analysis (F-test) significant differences between the individual function groups became clear.

[Incidence and therapy of fungal infections of the efferent urinary pathways]

Manifest infections with fungi of the urinary tract are rare in comparison with bacterial diseases and therefore they are often overseen. When this is concerned a funguria must always be clarified in chronic pyelonephritis. In patients with manifest infections with fungi without pronounced renal insufficiency 5-fluorocytosin is therapeutically very well suited on account of the renal elimination.

[Fungal infestation of the excretory urinary ways in chronic pyelonephritis]

374 patients with florid chronic pyelonephritis were examined concerning the frequency of a funguria. In primary diseases in 7.8% and in secondary forms in 12.4% of the cases fungi could be proved in the urine. Furthermore it is reported on course and therapy of manifest infections with fungi.

[Serum creatinine and endogenous creatinine clearance]

It is reported on the clinical evidence of the determination of creatinine and of the endogenic creatinine clearance. The determination of the serum creatinine gives a good parameter for the observation of the course in advanced renal insufficiency. The endogenic creatinine clearance which is often carried out in the clinical practice in the normal and moderately limited region allows in most cases sufficient measurement of the filtrate of the glomerulum. On 118 in-patients a method was tested which allows a nomographic estimation of the endogenic creatinine clearance on the basis of the actual serum creatinine level, taking into consideration age, sex, and bodyweight.

[Measurement of kidney function using combined PAH-inulin clearance before and after bactericide treatment of chronic pyelonephritis]

On account of the solution of the problem, whether already after a four weeks' therapy with antibiotics in chronic progressing pyelonephritis a measurable increase of function may develop, the combined PAH-inulin-clearance was performed 35 times. 9 patients did not show a clear restriction of the clearance, wherefore in these cases a control examination was not necessary. In 10 patients of 12 an increase was present, in 7 patients a significant increase of the renal function existed after the therapy carried out. Therefore already after antibiotic impact therapy in patients with chronic pyelonephritis without provable acute episode an improvement of the function can occur, which is to be increased or kept by means of the long-term treatment.

[A further case of Wissler's allergic subsepticemia in an adult]

A further case of subsepsis allergica Wissler in a 35-year-old woman is reported. The problems of the differential diagnosis of this rare disease are discussed. In the present case the disease could successfully be controlled using imuran in combination with corticosteroids.