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Biomedical subjects

A Kanfer

Publications and source records attributed to A Kanfer.

At least 37 records · Page 2Linked to original sources
PubMed1993

Methylprednisolone and cyclophosphamide pulse therapy in crescentic glomerulonephritis: safety and effectiveness.

In a previous study, we found that aggressive immunosuppressive therapy with continuous high-dose oral steroid and cyclophosphamide combined with plasma exchanges for extracapillary crescentic glomerulonephritis gave controversial results since, although disease activity was controlled, iatrogenic complications had led to death in some aged patients. We then modified our therapeutic regimen, and we analyze here the evolution of 30 consecutive patients who were admitted for biopsy-proven crescentic glomerulonephritis between 1989 and 1991. The mean plasma creatinine level at admission was 393 +/- 59 mumol/L (range 70 to 1100), and 15 patients had crescent formation in more than 50% of glomeruli on initial renal biopsy. Ten patients did not receive any immunosuppressive treatment since they either had a normal renal function or they had terminal renal failure and no severe extrarenal manifestation. The 20 other patients received initial steroid pulses 500 mg x3 (n = 17), low oral steroid treatment (n = 20), cyclophosphamide pulses (n = 13), or oral cyclophosphamide (n = 3). In 4 cases plasma exchanges were also used. As a whole, 10 patients (33%) were discharged with a normal renal function, and 18 patients (60%) had chronic renal failure, 7 of them requiring dialysis or transplantation; only 2 patients died of pulmonary hemorrhage. No severe iatrogenic complication was observed. These results indicate that reduction in oral steroid dosage, cyclophosphamide pulse therapy rather than continuous oral treatment, and plasma exchanges do not induce overimmunosuppression and iatrogenic complication. It can be safe, well tolerated, and as effective as a more intensive immunosuppressive regimen for the treatment of crescentic extracapillary glomerulonephritis.

Actuarial Analysis↗
PubMed1993

[Prognosis of rapidly progressive glomerulonephritis: the influence of age].

The evolution and prognosis of extracapillary glomerulonephritis were compared in two cohorts of patients treated between 1981 and 1986 (n = 39) and between 1989 and 1991 (n = 30). In the first group, the classical immunosuppressive treatment (steroids and cyclophosphamide) was given daily and combined with plasma exchanges. In the second group, IV pulses of methylprednisolone and cyclophosphamide were administered, followed by daily low-dose steroid therapy. Plasma exchanges were performed only in cases of extrarenal disease, particularly pulmonary hemorrhage. Although the two groups are not strictly similar, it could be concluded that aggressive immunosuppression including plasma exchanges impairs the vital prognosis by inducing infectious and/or hemorrhagic complications, especially in the elderly. On the other hand, methylprednisolone and cyclophosphamide pulses appear to have effectively treated extracapillary glomerulonephritis and were well tolerated. Thus they could be administered to all patients with rapidly progressive glomerulonephritis, including aged patients.

Adolescent↗
PubMed1992

[Reduction of TNF-alpha release and clinical effects of the first injection of OKT3].

In order to prevent the adverse effects of a first OKT3 injection in renal transplant recipients, we administered polyclonal antilymphocyte globulins (ATG Fresenius, 4 mg/kg/j) for 3 days before OKT3 injection. Compared with a historical group of 5 patients who did not receive ATG pretreatment before OKT3 injection, the patients who were pretreated by ATG had a significantly lower absolute number of circulating lymphocytes before the first OKT3 injection (363 +/- 107 vs 1,230 +/- 80/mm3, P < 0.001), a lower raise in plasma TNF-alpha level 2 hours after OKT3 injection (178 +/- 42 vs 735 +/- 127 pg/ml, P < 0.005) and a significant decrease in frequency and intensity of clinical symptoms, mainly chills, dyspnea, and headaches. However, fever and peak creatinine level were similar in both groups. A 80 percent success rate of crisis treatment was achieved in both groups and there was no increase in infectious complications. In conclusion, pretreatment with ATG induces a lymphocyte depletion, and decreases the amounts of TNF-alpha released as well as the side-effects of a first OKT3 injection.

Antilymphocyte Serum↗
PubMed1992

Quantification and modulation of thrombomodulin activity in isolated rat and human glomeruli.

Thrombomodulin (TM), the endothelial cell surface receptor for thrombin-mediated activation of protein C and of its anticoagulant system, is involved in maintaining vascular nonthrombogenicity, and depressed TM activity may induce intravascular fibrin formation. TM antigen was previously found by immunohistochemical methods in rabbit glomeruli. We therefore attempted to identify the corresponding TM activity in isolated detergent-solubilized rat and human glomeruli. Like purified lung TM, rat glomeruli extracts accelerated the hydrolysis by activated protein C of the chromogenic substrate S-2238 in the presence of 10 nM thrombin, as determined by spectrophotometry. One mg glomerular protein promoted the formation of 681 +/- 115 nmol activated protein C, the equivalent of the amount generated by 845 ng of purified rabbit TM. TM activity correlated with the protein content of the glomerular extracts (r = 0.94). These extracts prolonged rat plasma activated partial thromboplastin time. Incubation of glomeruli with tumor necrosis factor-alpha (TNF) or E. coli lipopolysaccharide depressed their TM-like activity in a dose and time dependent manner. Incubation with TNF suppressed their anticoagulant activity. In human glomeruli, TM activity was also found at a level which corresponded to their TM antigen content, and was determined by ELISA with mouse monoclonal antibody. These results indicate that measurement of glomerular TM activity might help to clarify the mechanisms of intraglomerular fibrin deposition in renal diseases.

Animals↗
PubMed1992

Glomerular coagulation system in renal diseases.

Glomeruli possess a complex hemostasis system with prothrombotic (procoagulant, antifibrinolytic) and antithrombotic (anticoagulant, fibrinolytic) properties that can act locally on platelet adhesion or aggregation, on plasmatic coagulation pathways, and on fibrinolysis. In vitro, inflammatory mediators, such as TNF, favor glomerular thrombogenic properties through enhancement of thromboplastin synthesis and of plasminogen activator inhibitor PAI-1, and through decrease in thrombomodulin activity. In some diseases, intraglomerular fibrin formation appears to be favored by increased glomerular prothrombotic properties, for example: augmented thromboplastin activity in immune glomerulonephritides and in Shwartzman phenomenon, excessive thromboxane A2 synthesis, and decreased fibrinolytic activity in severe renal allograft rejection. In other diseases glomerular hemostasis appears to function homeostatically, for example, in thrombin-induced disseminated intravascular coagulation with enhancement of fibrinolytic activity favoring fibrin dissolution. Novel methods allowing the study of glomerular hemostatic activities in renal biopsy fragments should help to understand the mechanisms of fibrin deposition in human diseases and to treat it on a logical basis.

Acute Kidney Injury↗
PubMed1992

[Role of hemostasis in the formation of crescents in extracapillary glomerulonephritis].

Extracapillary glomerulonephritis are associated with fibrin deposition in the urinary space of the glomerulus. Such deposits were correlated with the severity of the disease and with a poor renal outcome. Fibrin formation involves an activation of the coagulation cascade either through the intrinsic pathway, Hageman factor being activated by the altered glomerular basement membrane, either by the extrinsic pathway, infiltrating monocytes and glomerular cells exhibiting a procoagulant activity i.e. thromboplastin or tissue factor. Treatments with heparin or warfarin were shown to decrease the severity of experimental glomerular diseases. A similar beneficial effect was obtained with a monocyte-depleting serum and more recently with a treatment by a tissue type plasminogen activator. Glomerular cells also produce a fibrinolytic activity which could be too low or uneffective on extracapillary fibrin deposits if they contain high amounts of plasminogen activator inhibitors. Thrombin has procoagulant activity, antifibrinolytic activity and has cellular chemotactic and proliferative effects. It could play a major role in the pathogenesis of crescent formation.

Animals↗
PubMed1992

[Thrombosis and disorders of hemostasis in nephrotic syndrome].

Thromboses and disorders of hemostasis in nephrotic syndrome. Thromboembolic complications are common in nephrotic syndrome (NS). This article reviews the factors of thrombogenesis in NS, including: 1) a hypercoagulable state with platelet hyperaggregability, hyperfibrinogenemia and elevated factor VIII, decrease in plasma levels of coagulation inhibitors antithrombin III and free protein S, reduced fibrinolytic activity; 2) excessive intravascular thrombin formation marked by increased plasma levels of fibrinopeptide A. The intensity of hemostasis disorders coincides with that of NS. Most disorders are related to hypoalbuminemia and proteinuria. In agreement with experimental data, the role of intraglomerular activation of coagulation during active phases of glomerulopathies has to be considered. This could explain the predominance of renal vein thrombosis in several glomerulopathies with NS. Several coagulation disorders in SN have implications for therapy.

Blood Coagulation Disorders↗
PubMed1991

[Treatment of cytomegalovirus infections in renal transplants].

Primary cytomegalovirus (CMV) disease can be prevented in renal transplant recipient with the use of either CMV hyperimmune globulin or acyclovir. When started before transplantation and continued for 12 to 16 weeks, these treatments decrease significantly the incidence of primary CMV disease. However they are not always effective and their effectiveness for the prevention of CMV reinfection or reactivation has not been established. Other prophylactic methods, such as vaccination or interferon alpha are not effective. Ganciclovir has been shown to be effective for the treatment of overt CMV disease, provided it is administered early. Combined treatments with CMV hyperimmune globulins and ganciclovir can be used in the most severe forms of the disease. Foscarnet can also be effective, however its nephrotoxicity limits its use in renal transplant recipients.

Acyclovir↗
PubMed1990

Coagulation factors in nephrotic syndrome.

Nephrotic syndrome (NS) is associated with several disorders of hemostasis: thrombocytosis and platelet hyperaggregability; increased plasma levels of factors V and VIII, and of fibrinogen with blood hyperviscosity; decreased plasma levels of natural anticoagulants: free protein S, and antithrombin III compensated by increased levels of alpha 2-macroglobulin; lowered fibrinolytic activity. Intensity of hypercoagulability is related to the degree of hypoalbuminemia; however, the role of hypercoagulability in the increased incidence of thromboembolic events, including renal vein thrombosis, is not proved. Clotting disorders are due to urinary losses of anticoagulants or to increased liver synthesis of procoagulants stimulated by hypoalbuminemia. Moreover, changes in clotting factors levels may be due to intravascular thrombin formation (marked by increased plasma levels of fibrinopeptide A). During active phases of glomerulonephritides (GN) with NS, thrombin formation might in fact arise in glomeruli, following activation of the glomerular hemostasis system. Isolated glomeruli from human crescentic GN, rabbit nephrotoxic GN and rat HgCl2 autoimmune GN produce excessive amounts of procoagulant (tissue factor) activity (PCA). Sequential studies of the self-limited HgCl2 GN showed that glomerular PCA, proteinuria and glomerular fibrin deposits peaked concomitantly at the acme of the disease, suggesting that immunologically mediated glomerular damage had triggered the extrinsic coagulation pathway.

Blood Coagulation Disorders↗
PubMed1990

Fibrin deposition and adaptive changes in glomerular procoagulant and fibrinolytic activities in rat renoprival nephropathy.

To investigate the mechanisms which may influence fibrin deposition in the remnant kidney, glomerular morphology and the haemostatic properties of isolated glomeruli were assessed in two groups of rats, 30 days after surgical removal of three-quarters of the total renal parenchyma, and compared to glomeruli in sham-operated controls. One group was given the thromboxane synthetase inhibitor OKY 046 and the other was not. Fibrin deposition occurred in about 20% of glomeruli, of which 4% exhibited segmental necrotizing lesions. Concomitantly, glomerular procoagulant activity dropped to 40% of the control level and glomerular fibrinolytic activity rose to 120-130% of this level. Inhibition of thromboxane synthesis did not affect fibrin deposition, glomerular haemostasis or the development of renal insufficiency. In an additional group of unilaterally nephrectomized rats, procoagulant activity also markedly decreased in the remaining kidney. These results indicate that in the rat remnant kidney, alterations in glomerular haemostatic properties tend to have antithrombotic effects which seem to constitute an adaptive reaction by an autacoid system to glomerular fibrin deposition.

Adaptation, Physiological↗
PubMed1989

Role of coagulation in glomerular injury.

A role for coagulation in renal diseases is suggested by the presence of glomerular fibrin deposits in numerous experimental and human renal diseases, some of which are of toxic origin. Fibrin may exert detrimental effects by occluding glomerular capillaries, by attracting macrophages or by direct cytotoxicity to mesangial cells. Intraglomerular fibrin deposition or formation may result in part from changes in the normal multiple haemostatic properties of glomeruli. In glomerular clotting of systemic origin, e.g., glycerol-induced acute renal failure with intravascular coagulation, inhibition by drugs of glomerular fibrinolytic activity leads to persistent thrombi and permanent renal damage. In immune glomerulonephritis, fibrin formation may depend on activation of glomerular prothrombotic properties: for example, glomerular procoagulant (tissue factor-like) activity is enhanced at the peak of mercuric chloride-induced autoimmune glomerulonephritis, characterized by massive fibrin deposits. Finally, fibrin deposits probably contribute to the progressive renal lesions and chronic renal failure seen in rats with kidney damage, in which anticoagulant therapy has a beneficial effect.

Animals↗
PubMed1989

Plasma exchange and immunosuppression for rapidly progressive glomerulonephritis: prognosis and complications.

Rapidly progressive glomerulonephritis frequently leads to death or dialysis. In 21 cases treated by plasma exchange and immunosuppression we observed seven deaths, with 12 others progressing to chronic renal failure within 3 months. Patients who died were older than those who survived (57.5 +/- 17.7 vs 40.5 +/- 16.5 years, mean +/- SD, P = 0.05), but had similar clinical symptoms (hypertension, haematuria, proteinuria, extrarenal signs) and biochemical presentation (initial creatininaemia). They required the same degree of haemodialysis, of plasma exchanges and of bolus methylprednisolone. The causes of death were infection (three cases), cardiac arrhythmia (two cases) and gastrointestinal bleeding (two cases). Among the 14 remaining patients, only two recovered normal renal function. Twelve had chronic renal failure, six of them requiring chronic dialysis or transplantation. Severe renal failure at entry and anuria were more frequently observed in patients whose renal function did not improve during treatment. Plasma exchange and steroid bolus infusions also seemed to have a beneficial effect on renal function.

Adult↗
PubMed1989

Tamm-Horsfall protein accumulation in glomeruli during acetazolamide-induced acute renal failure.

A patient with ocular hypertension was treated with acetazolamide. Acute renal failure developed rapidly and renal biopsy showed mild tubular lesions and crystal formation in a tubular lumen. By immunofluorescence studies with a monoclonal antibody, Tamm-Horsfall protein, normally absent from the proximal segments of the nephron, was detected in most glomeruli. This strongly suggests that tubular obstruction plays a major part in some cases of acetazolamide-induced acute renal failure.

Acetazolamide↗
PubMed1989

Role of the renin-angiotensin system in the regulation of glomerular filtration.

Angiotensin II (Ang II) controls renal plasma flow, which depends on perfusion pressure and on renal vascular resistances; the glomerular filtration rate of single nephrons (SNGFR) also depends on these two parameters. The glomerulus can synthesize all components of the renin-angiotensin system. Renin is produced by mesangial cells and cells of afferent arterioles, angiotensinogen by mesangial cells, and angiotensin I-converting enzyme (ACE) by endothelial and mesangial cells. Ang II binds to afferent and efferent arterioles and to mesangial cells, which subsequently contract and enhance their production of vasodilator prostaglandins. Ang II participates in the regulation of the SNGFR by acting on arteriolar resistance, on the glomerular capillary surface area, and finally on the ultrafiltration coefficient. The synthesis of renin is initiated when the cAMP concentration increases under the influence of hormones (parathyroid hormone, catecholamines), of mediators (e.g., prostanoids), or of changes in composition of tubular fluid (in sodium, chlorine, or calcium) detected by the macula densa. Moreover, renin synthesis is stimulated by decreases in intracellular calcium concentration. The renin-angiotensin system plays an important role in the regulation of glomerular filtration. A decrease in renal plasma flow is followed by an increase in glomerular efferent arteriole resistance, so that perfusion pressure and glomerular filtration remain constant. Furthermore, if the decrease in renal plasma flow is more marked, vasodilator prostaglandins, whose synthesis is stimulated by Ang II, dilate afferent arterioles, which sustains glomerular filtration. Prostaglandins are also apt to bind to the juxtaglomerular apparatus and to increase the intracellular cAMP level.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Aseptic necrosis of bone following renal transplantation: relation with hyperparathyroidism.

Bone status, calcium and phosphate metabolism were prospectively evaluated in 98 renal transplant recipients with stable renal function. Aseptic necrosis of bone was found in 30 patients, leading to arthroplasty in 12 patients. Plasma parathyroid hormone and nephrogenic cyclic adenosine monophosphate (cAMP) values were greater and the duration of pre-transplant chronic renal failure longer in patients with aseptic necrosis of bone than in those who were not affected. Cumulative oral corticosteroid doses and the number of acute rejection episodes treated by intravenous methylprednisolone pulses were similar in patients with or without aseptic necrosis of bone. Hyperparathyroidism was confirmed histologically in 14 patients, comprising 4 cases of adenoma and 10 of diffuse hyperplasia. Serum parathyroid hormone correlated positively with serum creatinine (r = 0.47; P less than 0.001) and with cumulative corticosteroid dose (r = 0.30; P less than 0.003). This study suggests that hyperparathyroidism is a factor in the pathogenesis of aseptic bone necrosis. The frequency and severity of bone necrosis may be decreased by early detection and treatment of post-transplant hyperparathyroidism.

Adult↗