Enhancement of in-vitro human interleukin-1 production by sodium acetate

Human blood monocytes were incubated in vitro in the presence of various concentrations of sodium acetate or sodium chloride or with medium alone. Intracellular and extracellular levels of interleukin-1 (IL-1) were measured. The production of intracellular IL-1 and the release of extracellular IL-1 were higher in the presence of acetate than in the presence of chloride or in medium alone. The concentrations of acetate used were comparable to those encountered by blood monocytes on the surface of haemodialysis membranes. Since complications of peritoneal dialysis, such as loss of ultrafiltration and progressive fibrosis of the peritoneum, have been associated with the use of sodium acetate as the exchange-fluid buffer, these results suggest that the widespread use of sodium acetate as a buffer during haemodialysis may be contraindicated.

Performance and biocompatibility of the FD 100 Gambrane hollow-fiber dialyzer

In order to obtain performance data and biocompatibility characteristics of the two new Gambrane FD 100 polycarbonate hollow-fiber dialyzers (y-sterilized, dry or prefilled with isotonic saline) a paired in vivo evaluation was carried out. The measured data indicate that residual blood volume and small molecular weight clearances of Gambrane hollow-fiber dialyzers are not significantly different from comparable Cuprophan dialyzers. Small molecular clearance values are not affected by the significantly different ultrafiltration coefficients of the two tested FD 100 dialyzers. Biocompatibility of Gambrane as reflected by white blood cell count, platelet count and C3d is superior to Cuprophan.

[Drug treatment of chronic glomerulonephritis: pro]

This paper sets out the arguments for drug treatment of chronic glomerulonephritides (GN). Although the pathogenesis and mechanism of progression of chronic GN remained to be clarified, on the basis of controlled studies performed to date, there is a strong case to be made for an aggressive treatment approach to this disease spectrum. For instance, in patients with idiopathic membranous glomerulonephritis a six months treatment with chlorambucil (0.2 mg/KG/day) or prednisone (0.6 mg/KG/day) each given once a day over a period of three months has recently been shown to improve the outcome of the renal functional parameters after three years follow up. In another controlled trial a daily dose of 225 mg dipyridamole and 975 mg aspirin given over 12 months in patients with membrano-proliferative GN type I has been reported to normalize the increased platelet consumption rate and to stabilize the glomerular filtration rate. A third trial has demonstrated that the combined use of cyclophosphamide (100 mg/day) and prednisone (30 mg/day) over several months was superior to the use of prednisone alone (40 mg/day) in improving the long-term prognosis of diffuse-proliferative lupus nephritis (type IV, WHO). In some entities, however, as in IgA-nephritis there is still no evidence for a specific treatment improving the course of the chronic glomerular disease. Other therapeutic problems have to be solved: thus, in patients with minimal change nephropathy with a steroid dependent nephrotic syndrome the benefit of cyclophosphamide (given over three months) or of cyclosporin A is still being investigated. Furthermore, there is some evidence that progression of chronic GN, particularly that of glomerular sclerosing, can be prevented by a low protein diet. The role of eicosanoides and their inhibitors in this context has not yet been fully investigated. The different drug trials and new therapeutic concepts indicate a rapid development of chronic GN treatment. Therefore, a failure to treat actively is difficult to understand.

Is renal involvement a prognostic parameter in patients with infective endocarditis?

Renal involvement (RI)--defined as proteinuria greater than 150 mg per 24 h with haematuria or impaired glomerular filtration rate--was studied in 80 patients with infective endocarditis (IE). Proteinuria was measured quantitatively and further differentiated by the SDS-polyacrylamide-gel electrophoresis. RI was found in 40 patients (50%) with proteinuria from 150 to 8000 mg per 24 h. SDS-PAGE revealed a tubular protein pattern in 17 patients, a glomerular pattern in 6 and a glomerulo-tubular pattern in 17. Mortality rate was significantly higher in patients with RI (40%) than in those without (7.5%), and was not related to the type of infected valve, infective organisms, method of treatment (surgical or medical) or embolic events. Following successful treatment of IE, 18 out of 23 patients showed complete normalization of renal function. Renal involvement in patients with IE may be of prognostic significance--indicating an impaired prognosis.

Deficient feedback regulation of erythropoiesis in kidney transplant patients with polycythemia

Anemia of endstage renal failure improves shortly after kidney transplantation. However, in about 10% of transplanted patients polycythemia occurs. By use of a sensitive in vitro bioassay the pathogenetic role of erythropoietin (Ep) was investigated in 12 patients with post-transplant erythrocytosis (PTE), and compared to 12 non-PTE patients. The mean Ep of 160 mU/ml was significantly elevated in patients with PTE as compared to 25 mU/ml of 36 healthy controls, whereas, the mean Ep of 24 mU/ml in non-PTE patients did not differ significantly from healthy controls. To further elucidate the mechanism of inappropriate Ep production, selective venous catheterization of native and transplanted kidneys was performed in six patients. In four PTE patients the mean Ep in native kidney veins of 110 mU/ml was significantly higher than the peripheral Ep of 66 mU/ml, whereas, mean Ep in kidney graft veins was 51 mU/ml. In contrast, in two non-PTE patients no significant difference between mean Ep from native and transplanted kidney veins was observed. We conclude that some patients escape from normal feedback regulation either due to autonomous Ep production or due to feedback regulation at an elevated level of hematocrit and that inappropriate Ep production originates from the diseased native kidneys.

Hemodynamics in hemofiltration

To study the established but not well understood phenomenon of improved intratreatment vascular stability during hemofiltration the same 10 stable hemodialysis patients were investigated during one hemodialysis and one hemofiltration treatment. Both treatments were matched in regard to linear fluid withdrawal (3 kg/240 minutes), small molecule removal rate (Curea 120 ml/min). Sodium (140 meq/l) and acetate (35 meq/l) concentration in dialysate and replacement fluid were identical. Outcome measures included mean arterial blood pressure, total peripheral vascular resistance by thermodilution, plasma noradrenaline concentration as index of sympathetic activity and sodium loss per treatment. Blood pressure was maintained during hemofiltration, while total peripheral vascular resistance and plasma noradrenaline concentrations increased. During hemodialysis mean arterial blood pressure fell significantly, total peripheral resistance and plasma noradrenaline concentrations remained unchanged. During both treatment modalities sodium loss was comparable. It is concluded, that the improved hemodynamic stability during hemofiltration is due to a maintained physiologic response to ultrafiltration, which is impaired during hemodialysis. Vascular stability during hemofiltration is not due to sodium retention relative to hemodialysis.

Drug interactions with valproic acid

Valproic acid undergoes drug-drug interactions with most of the commonly used anticonvulsants. Since it possesses a wide range of indications, concomitant use with other anticonvulsants, and hence interactions, are not infrequent. Many of these interactions are reciprocal and may have important therapeutic consequences. Valproate acts as a protein binding displacer and/or metabolic inhibitor with respect to a number of other anticonvulsants (phenobarbitone, primidone, phenytoin). Inhibition of metabolism would, in most instances, result in a decrease of the dose requirements of the affected drugs. Valproate is a low clearance drug primarily eliminated by metabolism. Its metabolism is highly inducible by some of the major anticonvulsants (e.g. carbamazepine, phenytoin). Valproate is also highly protein bound in plasma and thus is displaced by salicylates and free fatty acids. However, displacement alone, unlike induced metabolism, should not affect the drug's dose-response relationship.

[Transplantation hyperparathyroidism--tumorlike growth and autonomous function of autografts of the hyperplastic parathyroid (author's transl)]

The results of clinical and morphologic studies performed in 41 patients with chronic, renal failure and secondary hyperparathyroidism, who had total parathyroidectomy and autotransplantation of parathyroid tissue into the forearm muscle are presented. In five cases, 7--33 months after autotransplantation we found transplantation tumors developing in the forearm. Explanted grafts showed invasive growth of parathyroid tissue in the adjacent structures, into the musculature and blood vessels. The increased incidence of mitosis otherwise seen as evidence of malignant neoplasia of parathyroid tumors, indicated atypical focal proliferation of the transplanted tissue. This is justification for not performing transplantations any more in the treatment of renal osteodystrophy.

[Skin changes in long-term dialysis patients. clinical study]

Fifty-one regular hemodialysis patients underwent clinicodermatologic examination. Twenty-three of them were on regular hemodialysis for 2-3 years (group I), 28 patients for more than 8 years (group II). Both groups were matched in regard to primary kidney disease, age, and sex. A characteristic feature found was a marked premature aging of the skin, mainly imposing as actinic elastosis. The incidence was related to the duration of hemodialysis (56.5% of patients of the first group and 100% of patients of the second group). There was also a correlation between time on hemodialysis and an increase of skin pigmentation. Other phenomena like xeroderma, decrease of sebaceous and sweat gland secretion, and Raynaud syndrome were also seen more frequently in the second group, but the extent of these alterations was equal in both groups. Seventy-eight percent of the patients of the first group and 43% of the second group suffered from generalized pruritus. Two different froms of pruritus could be observed, one possibly atopic, only occurring during regular hemodialysis, the other occurring independent of hemodialysis. accumulation of rare phenomena like carpal-tunnel syndrome and Dupuytren's contractures in group II together with the frequent occurrence of actinic elastosis implies systemic disturbance of collagen metabolism in long-term regular hemodialysis patients.

An outbreak of Achromobacter xylosoxidans related to diagnostic tracer procedures

In December, 1978, an investigation was undertaken to determine the source of infection in five patients in one hospital with hospital-associated bacteremia due to Achromobacter xylosoxidans. Review of their records showed that each had a diagnostic tracer procedure preceding the bacteremia and that no other procedures were common to all. Further investigation revealed that patients from three other hospitals were studied using diagnostic tracer materials from the index hospital. Five patients with confirmed A. xylosoxidans bacteremia and four suspected cases were identified in these hospitals, and all had a scan before the bacteremia was detected. No other A. xylosoxidans isolates were identified in any of the hospitals in the preceding two years. Although not confirmed, the source appeared to be stored non-bacteriostatic saline. Effective control measures included a sterility testing program and use of pre-packaged single dose vials of saline. Diagnostic tracer studies should be added to the list of procedures known to cause hospital-acquired bacteremias.

Sympathetic and hemodynamic response to volume removal during different forms of renal replacement therapy

Sympathetic and hemodynamic response to a constant volume removal was investigated during pure ultrafiltration, hemofiltration, acetate hemodialysis, and bicarbonate hemodialysis in the same ESRD patients. Small solute removal rates were matched. The sympathetic response resulting in an increase of total peripheral vascular resistance was found to be qualitatively adequate in ultrafiltration and hemofiltration, but not in acetate and bicarbonate hemodialysis. This inadequate response to volume removal explains the clinically observed hemodynamic instability during hemodialysis. The purpose of the study was to substantiate the, compared to hemodialysis, improved tolerance to fluid withdrawal during ultrafiltration and hemofiltration with hemodynamic data and to correlate hemodynamic and sympathetic changes during the different treatment modalities of uremia.

Phenytoin--valproic acid interaction in rhesus monkey

The interaction between phenytoin (PHT) and valproic acid (VPA) was investigated in the rhesus monkey. PHT was given by multiple IV bolus to reach a steady state and then continued while two successive VPA infusions were added. Plasma was assayed for total VPA and PHT as well as free PHT. The addition of VPA produced no change in total PHT levels, a 50% increase in PHT free fraction (increase in free PHT levels), and a decrease in PHT overall elimination rate constant. The increase in free fraction was also documented in a separate in vitro study. The increase in free PHT levels suggested that VPA decreased PHT intrinsic metabolic clearance. This interaction may thus involve a dual mechanism-namely protein binding displacement of PHT and inhibition of PHT metabolism. This mechanism is compatible with other studies showing that VPA is an inhibitor of drug metabolism.

[Autonomic circulatory regulation in uremia (author's transl)]

Uremic autonomic neuropathy leads to impaired function of the baroreflex. The main defect, according to literature, is located in the afferent limb of the reflex arc and in the efferent cardiac vagus nerve, whereas the sympathetic part of the efferent arc is still intact. Own results, obtained in hemodialysis patients during orthostasis and volume removal induced sympathetic stimulation, showed qualitatively and quantitatively adequate sympathetic response and also an adequate end organ receptor response. Autonomic nervous neuropathy predisposes to volume removal related symptomatic hypotension during hemodialysis treatment. In addition hemodialysis treatment per se induces a so far unexplained interference with sympathetic response to volume removal. The autonomic neuropathy also predisposes to development of hypertension in response to volume load.

Hemodialysis/hemofiltration: a report of a controlled cross-over study

In 14 stable ESRD patients an ABA cross-over study comparing conventional hemodialysis with post-dilution hemofiltration was performed in order to test the validity of clinical benefits reported for hemofiltration. No effect on blood-pressure could be observed in hypertensive hemofiltration patients when body weight was kept constant. The claimed positive effect of hemofiltration on hyperphosphatemia in dialysis patients could not be confirmed. A treatment with 3x81 I infusate per week seems to be insufficient treatment in regard to small molecule removal especially in heavy patients without any residual renal function. The decrease in urea nitrogen generation rate during the hemofiltration period might be the result of the lower small molecule removal in hemofiltration when compared to hemodialysis. The main clinical benefit of hemofiltration results from improved tolerance to volume removal due to improved hemodynamic stability during treatment.

Improving anemia by hemodialysis: effect of serum erythropoietin

Serum erythropoietin (SEP) concentration was measured on two occasions in 42 patients with terminal renal failure (1) immediately before the first hemodialysis, and (2) 3 to 27 months following the onset of regular hemodialysis treatment. Although the hematocrit (Hct) showed an increase in every patient, the SEP concentration decreased in every patient. The mean Hct rose frm 21.7 to 28.6% (volume per volume) P < 0.001), and the SEP dropped from 509 to 182 mU/ml (P < 0.001). This shows that anemia improvement is not a consequence of increased erythropoietin production but that it is most likely due to elimination of an inhibitor of the bone marrow by hemodialysis treatment. The decrease of SEP concentration has to be interpreted as a response to the improved tissue oxygenation that correlates with the hjigher hematocrit or as a consequence of further reduction of renal mass with progress of the renal disease.

Serum erythropoietin concentration in chronic renal failure: relationship to degree of anemia and excretory renal function

By use of the fetal mouse liver cell assay, serum erythropoietin (SEp) concentration was measured in 135 patients at various stages of chronic renal failure and in 59 healthy subjects. In patients with creatinine clearances (CCr) ranging from 2 to 40 ml/min/1.73 sq m, endocrine renal function was found to deteriorate in parallel to excretory renal function. The known negative correlation between SEp and hematocrit (Hct) was not apparent, probably because of the loss of renal mass accompanying progress of anemia and renal insufficiency. In contrast, in patients with minimal variation of residual excretory renal function, as in individual patients investigated repeatedly within a short period of time, changes of Hct were always accompanied by opposite changes of corresponding SEp concentrations. Thus, patients with chronic renal failure have a sustained regulatory feedback mechanism between Hct and SEp, which probably works at a lower level.