Formation of reactive oxygen metabolites in glomeruli is suppressed by inhibition of cAMP phosphodiesterase isozyme type IV

Several independent studies indicate that synthetic inhibitors of cyclic-3',5'-nucleotide phosphodiesterase (PDE) isozymes, especially inhibitors of PDE-IV, are potent agents which suppress generation of reactive oxygen metabolites (ROM) by NADPH oxidase in leukocytes. Recent studies also show that NADPH oxidase is present in all cell types populating glomeruli. In view of this, we investigated PDE isozymes and their relation to ROM in isolated rat glomeruli. Glomeruli have the capacity to hydrolyze cAMP by isozymes PDE-II, PDE-III and PDE-IV, whereas cGMP is hydrolyzed by PDE-I and PDE-V. Inhibitor of PDE-IV rolipram inhibited significantly (cca 40 to 50%) ROM generation in response to stimulation by phorbol myristate acetate (PMA). Inhibitor of PDE-III cilostamide had only minor suppressive effects and inhibitors of other PDE isozymes did not influence ROM generation. Rolipram (3 microM) suppressed ROM generation without detectable increase in cAMP content. Incubation of glomeruli with forskolin, which increased cAMP content in glomeruli tenfold, inhibited ROM generation to a similar degree as rolipram. The suppression of ROM generation by rolipram was prevented by Rp-cAMPS, a specific inhibitor of protein kinase A (PKA) activity. Further, incubation of glomeruli with rolipram elicited marked in situ activation of PKA (+ 100%), as documented by increase in the (-cAMP/+cAMP) PKA activity ratio. We suggest that selective inhibitor of PDE-IV rolipram acted via the cAMP-signaling pathway and suppressed ROM generation possibly via phosphorylating ras-type GTP-binding protein component of NADPH oxidase and thereby blocking assembly of functional NADPH oxidase complex.(ABSTRACT TRUNCATED AT 250 WORDS)

[Rapidly progressing glomerulonephritis with antibodies to glomerular capillary basement membrane]

Antiglomerular basement membrane glomerulonephritis was diagnosed in 14 patients (6 men and 8 women) aged 20 to 59 years. Five patients were found to have Goodpasture s syndrome. 5 rapidly progressive glomerulonephritis. 1 nephrotic syndrome, and 1 had mild glomerulonephritis. Blood pressure, proteinuria and haematuria were not severe in most patients. In 10 patients, the diagnosis was not established before end-stage renal failure had developed. Four patients died of lung haemorrhage, in 3 the haemorrhage was controlled by the treatment, in 3 renal failure without lung haemorrhage occurred, and in 3 renal function improved or was stable. The prognosis improved significantly after plasma exchange together with immunosuppression had been introduced.

Experimental adriamycin nephropathy. Fine structure, morphometry, glomerular polyanion, and cell membrane antigens

Two doses of adriamycin (2 mg/kg i.v.) were administered to young adult rats with a 22-day interval and the kidneys were examined 51, 79, and 107 days after the first injection. Light microscopy showed early prominent intraglomerular microcystic spaces and progressive, though not severe, segmental glomerulosclerosis with focal interstitial scarring and round-cell infiltration. The main features of the ultrastructure were widespread fusion of foot processes, focal cytoplasmic rarefaction of podocytes, and non-specific sclerosis of the mesangium without signs of severe degenerative changes or mesangiolysis. The segmental microcystic structures corresponded to agglomerated intrapodocytic vacuoles. The scatter of glomerular polyanion sites visualized by polyethylenimine-phosphotungstic acid resembled that of control animals but the quantitative assessment revealed a significant reduction. CD4-positive cells were the predominant element of the interstitial infiltrates. Most of the infiltrating cells expressed Ia antigens, whereas Ia-positive intraglomerular resident mononuclear cells were depleted. The adriamycin lesion resembles the post-five-sixths nephrectomy ablation nephropathy in the subpopulations of the interstitial infiltrate but differs from it in the reduction of intraglomerular resident macrophages, the absence of destructive mesangial damage, and reduced segmental glomerulosclerosis. The main feature is the prolonged damage of podocytes, especially of their cytoskeletal system.

[Long-term prognosis in chronic primary glomerulonephritis in relation to urinary findings]

A long-term followed-up group of 993 patients with primary glomerulonephritis (GN) was divided by urinary syndromes, defined according to the degrees of proteinuria and haematuria. Responding morphological diagnoses and prognoses were found for each urinary syndrome. Isolated and predominant haematuria were determined as benign, with stationary course even without immunosuppressive therapy. The prognosis of isolated, even moderate, proteinuria is more serious finding. Its relevance increases with the degree of haematuria. Severe combined proteinuria and haematuria is the most serious urinary syndrome. Both proteinuria and haematuria may be changing in the course of GN and increasing proteinuria points to the future glomerular filtration rate decrease.

[Focal segmental glomerulosclerosis]

Focal and segmental glomerulosclerosis accounted for 4.1% of all primary glomerulopathies. Typical signs of focal and segmental glomerulosclerosis were striking arteriolosclerosis on histological examination, the urinary syndrome of high proteinuria with mild haematuria and frequent nephrotic syndrome. The ten-year cumulative percentage of remissions was 30%. Patients with remission had at the time of biopsy a normal serum creatinine level and no or minimal regressive tubulointerstitial changes. The ten-year cumulative percentage of renal failure was 40%. Presence of nephrotic syndrome, extracapillary proliferation and advanced tubulointerstitial changes, tended to shorten a kidney survival. In one third of the patients the serum creatinine level rose by more than 50 mol/1/year.

Experimental ablation nephropathy. Fine structure, morphometry, cell membrane epitopes, glomerular polyanion and effect of subsequent transplantation

The subtotal (5/6) nephrectomy performed in 23 adult female rats induced severe hypertrophy of residual parenchyma with interstitial fibrosis, tubular dilatation, and focal and segmental glomerulosclerosis (FSG). This ablation nephropathy (AbN) caused proteinuria, progressive renal failure, and hypertension. The extent of FSG was assessed by semiquantitative scoring. The ultrastructure revealed widespread foot process fusion, many dense cytoplasmic inclusions in podocytes, and degenerative changes or disruption of mesangium with glomerular "microcysts". Numerous granular deposits of rat Ig were seen in the glomeruli but a short praeterminal i.v. load by heat-aggregated human Ig did not alter the morphology of AbN and produced discrete and inconstant glomerular deposits. Similarly an i.v. injection of protamine and heparin generated protamine-heparin complexes seen in various layers of glomerular capillary wall, similar to those found previously in normal rats. AbN displayed a partial irregular depletion of polyanion sites reactive with polyethylenimine in lamina rara externa. A significant increase in both glomerular and interstitial Ia+ cells and a marked predominance of W3/25+ cells in the interstitial infiltrates were documented by immunohistochemistry in the remnant kidneys. Both AbN and FSG could be largely corrected (or prevented?) by subsequent syngeneic renal transplantation (TPL; 6 animals). On the other hand a severe AbN was found in two post-ablation residues after unsuccessful TPL with graft necrosis or sclerosis.--AbN has some analogies to various chronic human nephropathies (e.g. FSG) and may explain their progression to the terminal failure. Degenerative and finally destructive mesangial lesion seems to be of prime importance in AbN.

[Type I and III membranoproliferative glomerulonephritis. Clinical picture and prognosis]

Membranoproliferative glomerulonephritis (CN) of types I and III was diagnosed in 154 patients (15.5% out of primary CN). Out of this number 60% were men. During biopsy, one third of the patients were normotensive, 40% were slightly hypertensive and one third suffered from severe hypertension. Mean proteinuria was 6.5 +/- 5.5 g/24 h. In two thirds of the patients erythrocyturia was higher than 35 mil. in Addis' sediment and the findings in the urine were characterised by the proportion between proteinuria and erythrocyturia (p less than 0.001). During biopsy in one half of the patients, the serum creatinine level was already elevated. The presence of creatininemia was found to be directly linked to blood pressure, proteinuria, the degrees of extracapillary proliferation, tubulointerstitial regression and vascular arteriolosclerosis. The cumulative duration of the kidney function within the period of 10-20 years was 41 or 28%, the cumulative cure amounted to 14% 10 years after biopsy.

Pharmacokinetics of roxithromycin in kidney grafted patients under cyclosporin A or azathioprine immunosuppression and in healthy volunteers

The pharmacokinetics of roxithromycin was studied in 9 kidney grafted patients under cyclosporin A immunosuppression, in 10 transplanted patients with azathioprine, and in 6 healthy volunteers. The biological half-life (beta-phase) of roxithromycin in cyclosporin patients was 34.4 (+/- 12.25) h (mean +/- SD), in azathioprine patients 23.4 (+/- 8.18) h and in healthy volunteers 17.0 (+/- 3.8) h. The total elimination constant (k10) was 0.046 (+/- 0.014), 0.068 (+/- 0.019) and 0.084 (+/- 0.036) h, respectively. The total clearance was 0.79 (+/- 0.21), 1.45 (+/- 0.66) and 1.84 (+/- 0.56) l/h, respectively. The areas under the serum level curves were 407.6 (+/- 118.3), 251.0 (+/- 106.6) and 180.7 (+/- 73.2) mg.h/l, respectively. The differences in these parameters between healthy volunteers and cyclosporin patients were statistically significant, as well as those between cyclosporin and azathioprine patients. The differences between healthy volunteers and azathioprine patients were not statistically significant. The results cannot be interpreted unambiguously as an interaction between roxithromycin and cyclosporin; the effect of cyclosporin on the function of eliminating organs which causes the slowed-down elimination of roxithromycin could be taken into account.

Comparison of three dosage regimens of ciprofloxacin in urinary tract infections

Fifty-four patients with complicated UTI were administered ciprofloxacin in doses of 500 mg (30 subjects) and 250 mg (24 subjects) at 12-hour intervals. While a positive effect was noted in 96-100% upon termination of therapy, the effect was still present 3 weeks later in 90% of the high-dose, but only in 71% of the low-dose group. In 23 patients with uncomplicated UTI, a positive effect of the three-day therapy with 100 mg of ciprofloxacin at 12-hour intervals was observed in 91% of subjects. Intolerance to the agent was found in one case only. Development of resistance to ciprofloxacin was not observed.

[Long-term effect of the administration of repeated single doses of netilmicin in urinary tract infections]

In 26 patients with different clinical forms of infections of the urinary pathways a 300 mg single dose of netilmicin was administered by the i.m. route and the bacteriological urinary finding was checked for as long as 10 weeks after administration of netilmicin. During this period the urine was bacteriologically negative in 42% of the subjects. In 8 subjects with relapses of the infection a second dose of 300 mg netilmicin was administered and the urine was bacteriologically negative for 10 weeks in four of the patients. On the whole it proved possible to eliminate the urinary infection for 42-112 days in 17 subjects (65%), even in so-called complicated infections. It may be stated that single dose treatment with netilmicin used once or repeatedly leads to prolonged elimination of the infection without affecting the sensitivity of the organisms, without side-effects and with a substantial reduction of the cost of treatment.

[Idiopathic membranous glomerulonephritis. Clinico-morphologic relations and prognosis]

Membranous glomerulonephritis (GN) was diagnosed in 61 of 993 patients with histologically confirmed primary GN. Two-thirds of the patients were men. High hypertension was recorded in 7.5% of the patients. A typical finding was marked proteinuria (6.15 +/- 4.88 g/24 h.) with mild erythrocyturia (median 8 million in Addis sediment). At the time of biopsy 86% of the patients had normal creatininaemia, the level of which was positively correlated with the blood pressure and degree of tubulointerstitial regression. The cumulative duration of renal function in 5, 10 and 20 years was 88, 80 and 57%; during the same time intervals 22, 48 and 52% of the patients were cured.

[Prevention of recurrent urinary infections using Solco Urovac, a polymicrobial vaccine]

The administration of Solco Urovac polymicrobial vaccine to 26 patients with recurrent episodes of urinary tract infection significantly reduced the number of episodes, in one third of the persons even prevented them for a period of one year. In case of persistent bacteriuria, accompanying, for example, nephrolithiasis, the vaccine had no effect. A better effect can be achieved in cases of uncomplicated infections of the lower urinary tract than in infections associated with structural abnormalities of the kidneys and urinary tract. In some patients, the administration of the vaccine is accompanied by mild side effects which, but only exceptionally, can lead to the discontinuation of the therapy.

Effect of methylprednisolone therapy on lipoprotein metabolism in human nephrotic syndrome

Changes in the lipoprotein metabolism of 15 patients with nephrotic syndrome concomitant with various types of the underlying renal disease after methylprednisolone therapy were investigated. Following methylprednisolone therapy, nephrotic syndrome remission was achieved only in three patients with minimal change disease. In these patients, total cholesterol (TC) and free cholesterol (FC) decreased and an increase in HDL-C and the HDL-C/TC ratio was found. In the remaining 12 patients, while marked proteinuria persisted after therapy, a significant increase in HDL-C (from 1.38 to 1.83 mmol/l) was noted with no significant changes in TC, FC and TG. Our results suggest that methylprednisolone may affect lipoprotein metabolism without necessarily exerting a favourable effect on the course of kidney disease.

[The effect of diphenylhydantoin on IgA nephropathy]

Seventeen patients with verified diagnosis of IgA nephropathy (15 men and 2 women) were divided into two groups using random selection. The group receiving treatment consisted of 9 persons, the control group was made up of 8 persons. The former group were given diphenylhydantoin in doses of 2-3 mg/kg/day for a period of 6 months. After the termination of the course of treatment, the authors found a drop in the levels of serum immunoglobulins A, G, complement components C3, C4, circulating immunocomplexes, and decreased haematuria, and, in contrast, increased levels of serum creatinine. No undesirable effects of diphenylhydantoin were noted.

Defect in cholesterol esterification associated with renal diseases

Changes in lipidaemia and in cholesterol esterification rate were investigated in 65 patients with chronic mesangial glomerulonephritis (GN), and in 26 patients with polycystic kidneys (PL), as well as in age- and sex-matched control groups. As compared to the controls, a slightly significant increase in cholesterol and triglyceride concentrations was found only for the GN group, whereas the rate of cholesterol esterification showed a highly significant reduction in both groups of diseased subjects. The average values of molar esterification rate (MER) were, respectively, 75.4 and 61.6 mumol . l-1 . h-1 for the GN and PL groups, the respective control values being 96.9 and 91.1. Fractional esterification rate (FER) reflecting the rate of cholesterol exchange between blood and tissues fell in the same two groups of patients to 4.38 and 4.40% . h-1, respectively (controls 6.93 and 6.17). Both the changes in cholesterol esterification rates and a relative increase in the ratio of unesterified to esterified cholesterol were found in patients with low as well as normal glomerular filtration rates.

Protein aggregates in extracorporally perfused rabbit kidneys

Eighteen rabbit kidneys were perfused ex vivo for 1 h with allogeneic blood, and in 16 a solution of xenogeneic aggregate-free, aggregated or antibody-complexed protein was added to the perfusate 5 min after the start (human immunoglobulins or serum albumin, partly cationized, were used). The kidneys were examined by light and electron microscopy and the human and rabbit immunoglobulin (or albumin) precipitates were detected by direct immunofluorescence and ultrastructural immunohistochemistry. In 13 kidneys the perfusion produced small segmental glomerular endocapillary aggregates of platelets, leukocytes, and granular precipitates reactive with both anti-rabbit and anti-human antibodies. No typical deposits were seen in mesangium or in periphery of glomerular capillaries but rabbit Ig penetrated to the inter- and subepithelial spaces of proximal convoluted tubules. Three kidneys perfused by cationized aggregated human Ig (or by cationized albumin-antialbumin complexes) exhibited a destructive lesion with rapid breakdown of blood flow and massive global endocapillary plugs of similar ultrastructure but with focal endothelial sloughing. Pericapillary granular precipitates of human and rabbit Ig were seen in these kidneys. When the blood with cationized Ig aggregates was used for perfusion of two further kidneys extensive endocapillary aggregates with endothelial damage reappeared but the extracapillary penetration and precipitation were lacking and the blood flow largely improved. Membrane polyanion of podocytes stained by colloidal iron was preserved even in close proximity of cationized complex precipitates. Thus, in the ex-vivo perfusion model the preformed neutral aggregates did not penetrate through the glomerular capillary wall and were not phagocytized by mesangial cells. The cationized aggregates induced rapid circulatory failure with massive platelet clumping and granular pericapillary "humps" ultrastructurally different from the deposits of human and experimental immune complex glomerulonephritis.