Weight-independent dosing of cyclosporine--an alternative to the "mg/kg" doctrine.

Cyclosporine is usually prescribed as "mg CsA per kg body weight", and blood levels are used for guiding CsA therapy. The present study evaluated whether it is sensible to dose in "mg/kg" if one wishes to obtain specific CsA blood levels. In a retrospective analysis, 1071 consecutive CsA whole-blood trough levels from 164 renal transplant patients, measured by monoclonal parent RIA, were correlated with the respective oral CsA doses and several demographic parameters, including gender, age, weight, height, and time after transplantation. From this, we derived a concept of "weight-independent CsA dosing" which was prospectively tested in three series of patients during the first days after renal transplantation: 58 patients received 2x 100 mg/day CsA from day 0 with the intention to reach target levels of 40-80 ng/ml, 42 patients received 2x 200 mg/day CsA from day 4 (target: 100-200 ng/ml), and 38 patients received 2x 300 mg/day from day 4 (target: 100-200 ng/ml). In the retrospective analysis, the individual, patient-specific relation of CsA level to CsA dose (in mg) was found to depend only on height (P = 0.02) and time after transplantation (P < 0.001), but not on body weight (b. wt.). If the CsA dose was expressed in "mg/kg", patients < or = 55 kg b. wt. required nearly twice the doses of patients > or = 75 kg b. wt., whereas the mean CsA requirement was the same when expressed in "mg".(ABSTRACT TRUNCATED AT 250 WORDS)

A randomized prospective trial of prophylactic immunosuppression with ATG-fresenius versus OKT3 after renal transplantation.

We carried out a randomized prospective trial to compare OKT3 (5 mg/d, 51 patients) with ATG-Fresenius (ATG-F, 4 mg/kg/d, 53 patients) for induction therapy after renal transplantation, concerning side effects, rejection, and infection incidence within a one year follow-up period. Concomitant immunosuppression included azathioprine/steroids from day 0 and cyclosporine A from day 4. OKT3 patients experienced significantly more and more-severe side effects, particularly pyrexia, headache, and pulmonary fluid overload. One-year graft survival was excellent in the ATG-F group (91%), but only 78% in the OKT3 group (P < 0.05) due to a series of rejections that occurred beyond day 100; patient survival (96% and 92%) was similar in both groups. OKT3-treated patients experienced more biopsy-proven rejections (0.6 +/- 0.1/pt.) than ATG-F patients (0.3 +/- 0.1, P < 0.05), and there was a similar, albeit not significant trend in clinical rejections (OKT3: 1.1 +/- 0.2/pt.; ATG-F: 0.8 +/- 0.1/pt.). Infections were more common in the OKT3 group (OKT3: 3.2 +/- 0.3, ATG-F: 2.0 +/- 0.2, P < 0.05), although this was entirely attributable to "minor" infections. On days 1 through 6, CD3 counts were more profoundly depressed with OKT3 therapy. Beyond day 10, however, CD3 counts were lower in the ATG-F group, as were CD2 counts, CD4 counts, and the CD4/CD8 ratio, suggesting a more prolonged immunosuppressive effect of ATG-F. Sensitization occurred more frequently with OKT3 (31%) than with ATG-F (10%), but was usually irrelevant, except in two patients (one in each group), whose grafts were lost because of immunization against OKT3 and ATG-F, respectively. In conclusion, a 7-day induction therapy with OKT3 does not improve outcome or diminish immunological graft loss when compared with ATG-F, but is associated with more rejections, infections, and side effects. ATG-F appears to be preferable for induction immunosuppression after renal transplantation.

[Follow-up care of living kidney donors]. / Nachbetreuung von lebenden Nierenspendern.

The follow-up of living kidney donors demands medical as well as psychological competence. In the postoperative period, attention focuses on pain management, early detection of wound complications and the prophylaxis of thromboembolism. Regular visits of the donor who may easily feel neglected should be as much part of the transplant team's post-operative routine as visits of the recipient. The later phase of recovery emphasizes strengthening abdominal wall and lumbar muscles as well as the gradual increase of physical activity. Long-term follow-up focuses on the early detection of arterial hypertension and proteinuria. Antihypertensive therapy in nephrectomized donors should include an ACE inhibitor or an angiotensin-II antagonist. In Switzerland, the long-term course after living donation is prospectively monitored by the Swiss Registry for Living Donors founded in 1993. The registry is responsible for the regular timing of follow-up examinations and assures transparency of the origin of the kidneys used for living donation in Switzerland. The registry heavily relies on the collaboration of the donor's family physicians.

Pathogenesis of acute renal failure: new aspects.

Based on 2 case presentations - acute renal failure (ARF) due to myeloma kidney and due to angiotensin-converting enzyme inhibitor administration in the presence of transplant artery stenosis - new aspects in the pathogenesis of ARF are presented and discussed. The multifactorial pathogenesis of ARF includes (a) a disturbance of glomerular microcirculation (afferent and perhaps mesangial constriction, inadequate efferent dilatation); (b) a disturbance of medullary microcirculation (medullary capillary congestion) attributed to a combination of endothelial damage and tubular dilatation; (c) tubular cell damage which, though rarely in humans justifying the term 'acute tubular necrosis', promotes both backleak of glomerular filtrate and shedding of brush border vesicles; (d) the latter promotes tubular obstruction by casts which consist of Tamm-Horsfall protein and brush border components. Once ARF is established, repair processes set in which appear to depend on growth factors such as epidermal growth factor and insulin-like growth factor 1, of which there is a relative shortage in established ARF. Experimental therapeutic approaches focus on the restitution of microcirculation (endothelin receptor antagonists, atriopeptins), interference with cast formation (integrin receptor blockers), and the promotion of recovery by growth factors.

Steroid-resistant kidney transplant rejection: diagnosis and treatment.

Decreases in transplant function may be attributable to a variety of conditions, including prerenal and postrenal failure, cyclosporin A (CsA) toxicity, polyoma nephritis, recurrent glomerulonephritis, and rejection. The diagnosis of rejection should therefore be made on the basis of a transplant biopsy of adequate size, before the initiation of any therapy. Pulse steroid treatment (three to five 0.25- to 1.0-g pulses of methylprednisolone, administered intravenously) is the usual first-line therapy and has a 60 to 70% success rate, although orally administered prednisone (0.25 g) may be just as efficacious. Even if reverted, any rejection should trigger an at least temporary increase in basal immunosuppression, consisting of an increase in CsA or tacrolimus target levels, the addition of steroids or an increase in their dosage, the addition of mycophenolate mofetil, or a switch from CsA to tacrolimus. The addition of rapamycin or its RAD derivative may fulfill the same purpose. Steroid resistance should not be assumed before the fifth day of pulse steroid treatment, although histologic features of vascular rejection may indicate the need for more aggressive treatment earlier. Steroid-resistant rejection is traditionally treated with poly- or monoclonal antilymphocytic antibodies, with success rates of 60 to 70%. Their potential benefit must be carefully balanced against the risks of infection and lymphoma. More recently, mycophenolate mofetil has been successfully used to treat steroid-resistant rejection, but only of the interstitial (cellular) type. Switching from CsA to tacrolimus for treating recurrent or antibody-resistant rejection is successful in approximately 60% of cases. Plasmapheresis and intravenously administered Ig have been used in some desperate cases, with surprising success. Because none of the available drugs has a significantly better profile of therapeutic versus adverse effects, the possible benefits of continued rejection therapy must be continuously balanced with the potential for serious, sometimes fatal, side effects.

The endothelial L-arginine/nitric oxide pathway and the renal circulation.

Endothelial cells contain an enzyme(s) which produces nitric oxide from L-arginine in response to a variety of mechanical stimuli as well as to autacoids and local and circulating hormones. Nitric oxide is a potent vasodilator and inhibitor of platelet function; it exerts its effects via activation of soluble guanylate cyclase and subsequent formation of cyclic 3'-5'-guanosine monophosphate. In the kidney, activation of the endothelial L-arginine pathway is associated with increases in renal blood flow, diuresis and natriuresis, while the glomerular filtration rate remains constant. The activity of the endothelial L-arginine pathway is impaired in hypertension and during chronic therapy with cyclosporine A. In addition, diabetes and atherosclerosis impair this pathway. Thus, the endothelial L-arginine pathway plays an important role in the local regulation of blood flow. Alterations in the activity of this pathway may play an important role in the pathophysiology of hypertension and renal disease.

Glomerular hyperfiltration after unilateral nephrectomy in living kidney donors.

Glomerular hyperfiltration, which is expected to occur after uninephrectomy, could potentially damage the non-transplanted donor kidney in living donor transplantation. We therefore prospectively measured renal function (inulin and PAH clearance), albumin excretion and blood pressure in the donors of 30 consecutive living donor kidney transplants before uninephrectomy (n = 29) and 1 week (n = 27) and 1 year (n = 16) after. Hyperfiltration was defined as: (post-nephrectomy inulin clearance)/(0.5 x pre-nephrectomy inulin clearance); hyperperfusion was defined in an analogous way for PAH clearance. Hyperfiltration averaged 128 +/- 5% [SEM] and hyperperfusion 133 +/- 6% 1 week after uninephrectomy. Hyperfiltration was nearly unchanged (126 +/- 7%) 1 year after nephrectomy, whereas hyperperfusion had significantly decreased to 118 +/- 8% (P < 0.02). There was no significant change in blood pressure after nephrectomy, and no new cases of hypertension were observed during the 1-year follow-up. The degree of hyperfiltration did not correlate with donor age. Microalbuminuria > 30 mg/24 h was found in two donors 1 week after nephrectomy (one of which normalized at 1 year) and in one additional donor 1 year after nephrectomy. The degree of hyperfiltration did not correlate with albumin excretion rate. In conclusion, no adverse consequences of hyperfiltration were demonstrable during the 1-year observation period, but the prognostic role of occasional microalbuminuria should be further investigated.

Hyperuricaemia in cyclosporin-treated patients: GFR-related effect.

BACKGROUND: Hyperuricaemia is a well known side-effect of cyclosporin A (CsA) treatment. The pathogenic mechanisms, however, remain controversial. There is no convincing evidence that hyperuricaemia is due to CsA-induced, impaired tubular handling of uric acid. The impact of diminished GFR in this particular context has never been investigated. METHODS: We prospectively studied plasma uric acid, inulin clearances, and fractional clearances of uric acid in two groups of CsA-treated patients (bone-marrow transplant patients, n = 50; renal transplant patients, n = 32), and one healthy control group without CsA (living related kidney donors, n = 28). Bone-marrow transplant patients were examined before transplantation and 6, 12, 18, 24 months after transplantation, renal transplant patients 1 year after transplantation, and living related kidney donors before and 1 year after unilateral nephrectomy. RESULTS: After 1 year of CsA treatment, hyperuricaemia was found in 36% of bone-marrow transplant patients and in 53% of renal transplant patients. Thirty per cent of living related kidney donors were borderline hyperuricaemic 1 year after unilateral nephrectomy. The fractional clearance of uric acid, measured serially in bone-marrow transplant patients did not change significantly over time; it was, however, slightly higher during CsA treatment than after CsA withdrawal. Moreover, the bone-marrow transplant patients' fractional clearance of uric acid was not statistically different from the renal transplant patients' and the living related kidney donors' (values 1 year after transplantation/unilateral nephrectomy: bone-marrow transplant patients, 15.3 +/- 2.3%; renal transplant patients, 11.9 +/- 0.9%; living related kidney donors, 11.1 +/- 0.8%). The GFR at 1 year measured by inulin clearance, was identical in the CsA-treated groups and slightly higher in the living related kidney donors (bone-marrow transplant patients, 51 +/- 6 ml/min per 1.73 m2; renal transplant patients, 49 +/- 3 ml/min per 1.73 m2; living related kidney donors, 61 +/- 2 ml/min per 1.73 m2). CONCLUSION: There is no evidence for impaired tubular handling of uric acid, induced by a CsA-specific tubulotoxic effect. Hyperuricaemia in CsA-treated transplant patients can therefore be attributed to the cyclosporin-associated decrease of GFR.

Real and artefactual erythrocyte swelling in hyperglycaemia.

The mean erythrocyte volume of patients with acute diabetic decompensation was determined by Coulter measurement and found to be elevated above normal (mean increase 5.5 mu3). Experiments in vitro revealed this to be an artefact associated with Coulter determination. A more reliable estimate of in vivo erythrocyte volume can be obtained from centrifugated haematocrit and erythrocyte count. With this method, true erythrocyte swelling parallel to glucose concentration was observed when erythrocytes were exposed to isotonic glucose-NaCl solutions. This volume increase resulted from decreased sodium concentration and was in the order of 0.5-1.0 mu3 per mmol/l of sodium. Glucose was osmotically ineffective. Similar volume changes were documented in a diabetic patient parallel to his daily variations of blood glucose. In severe diabetic decompensation, dehydration usually prevents an increase in erythrocyte volume. We conclude that hyperglycaemia is associated with erythrocyte swelling if total serum tonicity remains within the normal range.

Monoclonal gammopathy after intense induction immunosuppression in renal transplant patients.

OBJECTIVES: Incidence and risk factors of post-transplant monoclonal gammopathy were studied in renal transplant patients who received their grafts between 1982 and 1992 (n = 390 grafts). Immunoelectrophoresis was performed at annual intervals after transplantation. RESULTS: Forty-six cases of clonal gammopathy were detected: 35 monoclonal, 11 bi- or triclonal, with a predominance of IgG and kappa light-chain subtypes (IgG, 39; IgA, 3; IgM, 4; kappa, 35; lambda, 19). Gammopathy was incidence of gammopathy was 10.7%, much higher than expected for a group of similar age from the general population. Thirty of the 46 gammopathies appeared within the first 2 years of transplantation. Gammopathy never progressed to multiple myeloma during follow-up (median 1 year; (range 0-10)); one patient subsequently developed Kaposi sarcoma. The 2-year incidence of gammopathy was much higher in patients transplanted in 1989-1991 (23/142) than in 1982-1988 (7/248) (P < 0.0001). This coincided with the use of quadruple induction immunosuppression (cyclosporin A+azathioprine+prednisone plus either ATG-fresenius (ATG-F) or OKT3) since 1989. The risk for acquiring gammopathy within 2 years of transplantation was 14.7% (95% CI 9.2, 20.3%) in patients receiving quadruple induction therapy, but only 3.0% (CI 1.2, 6.1%) without such therapy (P < 0.0001). The risk for patients receiving quadruple immunosuppression with OKT3 was 24.5%, significantly greater than with ATG-F (11.8%, P < 0.05). Discriminant analysis revealed that the type of immunosuppression, but not age or year of transplantation, were independent risk factors for gammopathy. CONCLUSION: Monoclonal gammopathy frequently occurs after renal transplantation. Risks are higher for patients receiving quadruple induction immunosuppression, particularly if it includes OKT3. Follow-up of these patients is warranted for the early detection of malignant transformation.

Excellent uricosuric efficacy of benzbromarone in cyclosporin-A-treated renal transplant patients: a prospective study.

Patients on cyclosporin A (CsA) often develop hyperuricaemia and gout. In transplant patients the use of uricosuric drugs for treating hyperuricaemia may be preferable to allopurinol because of the known interaction of the latter with azathioprine. We therefore prospectively studied the uricosuric efficacy of 100 mg benzbromarone (Bbr;Desuric) daily in 25 CsA-treated renal transplant patients with stable graft function and hyperuricaemia (> 359 mumol/l for females, > 491 mumol/l for males). Benzbromarone decreased plasma uric acid from 579 + 18 mumol/l to 313 +/- 24 mumol/l (mean +/- SEM; P < 0.0001) and thereby normalized plasma uric acid in 21 of 25 patients. The remaining four patients had creatinine clearances between 21 and 25 ml/min, the lowest of the entire study group. Mean fractional clearance of uric acid increased from 5.4 +/- 0.4% to 17.2 +/- 1.0% (P < 0.001). The relative decrease of plasma uric acid closely correlated with baseline creatinine clearance (r = 0.67; P < 0.001). CsA trough values were not influenced. None of the patients experienced any significant side-effects. As an unexpected find-ing, urinary uric acid excretion increased from 2082 +/- 175 mumol/24 h to 3233 +/- 232 mumol/24 h after 4 weeks' treatment with benzbromarone. In conclusion, benzbromarone normalized plasma uric acid in all CsA-treated renal transplant recipients with a creatinine clearance > 25 ml/min. Due to its excellent efficacy and lack of significant side-effects, benzbromarone appears to be preferable to allopurinol in CsA-treated renal transplant recipients with a creatinine clearance over 25 ml/min.

Pressure dependent modulation of renin release in isolated perfused glomeruli.

The isolated perfused glomerulus technique was used to study pressure dependence of renin release in single, microdissected rabbit glomeruli with intact afferent arteriole and intact Bowman's capsule. Renin release from individual afferent-glomerular units was measured in 30 minute intervals while afferent arteriolar pressure was either decreased from 55 to 40 to 25 mm Hg or increased from 25 to 40 to 55 mm Hg. There was a clear, inverse relation of renin release and afferent pressure. Mean renin release rate was 3.2 times higher at 25 than at 55 mm Hg and 1.5 times higher at 40 than at 55 mm Hg. To evaluate the possible role of wall stretch in mediating this response, inner and outer afferent arteriolar diameters were measured by videomicroscopy. Outer afferent diameter remained constant between 25 and 55 mm Hg, whereas inner diameter exhibited a slight increase. Changes of afferent arteriolar wall stretch, however, did not correlate with changes of renin release. These data for the first time directly demonstrate the existence of a renin baroceptor at the level of the renal afferent arteriole. They furthermore suggest that this baroceptor is not a stretch receptor.

Effects of intravenous aspirin on prostaglandin synthesis and kidney function in intensive care patients.

The effects of intravenous acetylsalicylic acid (1.0 g bolus) on renal function and prostaglandin synthesis were evaluated in a prospective, controlled study in eight patients in an intensive care unit. Four of these patients had congestive heart failure. Administration of acetylsalicylic acid caused significant antidiuresis (-56%), antinatriuresis (-82%), renin suppression (-26%) and decreased GFR (-41%). All of these changes were completely reversible within 1-2 hours and tended to be more pronounced in the patients with congestive heart failure. Urinary excretion of prostaglandin E2 was depressed profoundly (-93%) and did not return to more than 45% of control 6 h after the administration of acetylsalicylic acid. We conclude that intravenous acetylsalicylic acid affects kidney function in a manner similar to other prostaglandin synthesis inhibitors. Its effects are, however, short-lived. The inhibition of urinary PGE2 excretion outlasts GFR depression, antidiuresis, antinatriuresis and renin suppression by several hours.

Measurement of renin secretion in single perfused rabbit glomeruli.

A new technique is presented that allows the measurement of the renin secretion rate of single rabbit glomeruli during in vitro perfusion at controlled afferent arteriolar perfusion pressure. Rabbit glomeruli with intact afferent arteriole and Bowman's capsule are obtained by microdissection and cannulated with a pipette system that allows continuous afferent arteriolar pressure measurement. The renin secretion rate of 10 glomeruli, perfused at 40 mmHg, was measured in 15-min intervals with an antibody-trapping microassay. Renin secretion rate was low relative to total renin content (1.2-2.0% of content/perfusion h) and increased three- to fivefold in response to isoproterenol (10(-5) M). The afferent arteriole contracted to norepinephrine (10(-5) M) in each instance. This novel, although difficult, technique allows the study of renin release in vitro at controlled perfusion pressure, without the interfering effects of the macula densa, arterial angiotensin II, and the adrenergic nervous system. It should allow a new perspective on issues such as the pressure-flow dependence of renin release and the interaction of the afferent arteriolar endothelium with the renin-secreting juxtaglomerular cells.

Long-term enalapril and verapamil in rats with reduced renal mass.

The effect of long-term treatment with either enalapril or high dose verapamil on survival, proteinuria, blood pressure and renal morphology was studied in female Wistar rats with markedly reduced renal mass. Four weeks were allowed for remnant kidney hypertrophy before determining the response to renal ablation of individual animals regarding proteinuria and hypertension. At this time, five groups of 18 rats were formed with equal levels of proteinuria and hypertension. Groups E1 and E2 were treated with enalapril, groups V1 and V2 with verapamil, and one group served as control. The daily food allowance was 14 g/rat of a standard rat diet, containing 30% protein and 100 mmol NaCl/kg food in groups E1 and V1. NaCl content was reduced to 20 mmol/kg food in groups E2, V2 and control. The drugs were added to the drinking water, enalapril at a dose of 0.1 g/liter, verapamil at 0.5 to 0.7 g/liter. Drug intake thus amounted to 10 to 25 mg/kg for enalapril and 50 to 140 mg/kg for verapamil. Treatment was continued for 15 weeks. Three of the 18 control rats did not survive up to 15 weeks. Mortality was lower in the enalapril treated groups with a single nonsurvivor in group E1. In contrast, mortality was higher in the verapamil treated animals with seven nonsurvivors in group V1 and eight in group V2. Blood pressure control was excellent in both enalapril treated groups. and proteinuria decreased in most animals of group E1 and all of group 22. Glomerulosclerosis did not develop in the majority of the enalapril treated animals. Despite the high dose, verapamil barely lowered blood pressure.(ABSTRACT TRUNCATED AT 250 WORDS)

Control of hypertension by verapamil enhances renal damage in a rat remnant kidney model.

The effect of calcium channel blockers on the progression of renal failure is controversial. In contrast with earlier studies, we recently reported that moderately large doses of verapamil significantly accelerated chronic renal failure in the rat remnant kidney model. Studies reporting beneficial effects of verapamil were characterised by a much lower dose of verapamil and by the start of treatment immediately after renal ablation, which potentially interfered with the initial phase of remnant kidney hypertrophy. We therefore studied the effects of a high, fully antihypertensive oral dose of verapamil (100-150 mg/kg/per day; group Vera high) and a low, haemodynamically almost ineffective dose (10-15 mg/kg per day; group Vera low), on the progression of chronic renal failure in female Wistar rats with 5/6 nephrectomy. The treatment was started no earlier than 5 weeks after renal ablation, and matched groups of 20 animals were followed for 16 weeks thereafter. High-dose verapamil reduced systolic blood pressure to median values of 130-140 mmHg throughout the experimental period, whereas blood pressure in Vera low animals remained elevated at median values of 165-172 mmHg similar to non-treated rats with 172-185 mmHg median systolic blood pressure.(ABSTRACT TRUNCATED AT 250 WORDS)

Failure of verapamil to protect from ischaemic renal damage.

To reassess the reported protective effects of verapamil in renal ischaemia, we perfused the left kidney of uninephrectomized female Wistar rats with verapamil (0.1 and 1.0 mg/kg) immediately prior to clamping the renal artery for 60 min. When compared to controls, both doses of verapamil failed to afford protection with respect to urine flow, plasma creatinine, creatinine clearance or histology 24 and 48 h after ischaemia, whereas the purine nucleotide inosine (200 mg/kg) was partially protective: mean plasma creatinine 48 h after ischaemia (+/- SEM) was 547 +/- 54 mumol/l in controls, 686 +/- 38 mumol/l with 0.1 mg/kg verapamil, 491 +/- 68 mumol/l with 1.0 mg/kg verapamil and 374 +/- 45 mumol/l with inosine (p less than 0.05 vs. controls). Using the same model, the effect of verapamil 1.0 mg/kg on renal blood flow, creatinine clearance, urine flow and arterial pressure was studied in the first 2 h after ischaemia. Although significant amounts of verapamil were present in the kidney during ischaemia as evidenced by decreases in systemic blood pressure and in renal vascular resistance after unclamping the renal artery, the early course of renal failure was not altered when compared to controls. In conclusion, we have been unable to confirm earlier reports of a protective effect of verapamil in this rat model of ischaemic renal failure. If there is such an effect, its demonstration appears to depend on very specific experimental circumstances. Based on the results of this and other studies, verapamil is unlikely to afford an impressive overall benefit in the clinical setting of ischaemic renal failure.