Biomedical subjects
Publications and source records attributed to R Habib.
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Denys-Drash syndrome is a rare human condition in which severe urogenital aberrations result in renal failure, pseudohermaphroditism, and Wilms' tumor (nephroblastoma). To investigate its possible role, we have analyzed the coding exons of the Wilms' tumor suppressor gene (WT1) for germline mutations. In ten independent cases of Denys-Drash syndrome, point mutations in the zinc finger domains of one WT1 gene copy were found. Nine of these mutations are found within exon 9 (zinc finger III); the remaining mutation is in exon 8 (zinc finger II). These mutations directly affect DNA sequence recognition. In two families analyzed, the mutations were shown to arise de novo. Wilms' tumors from three individuals and one juvenile granulosa cell tumor demonstrate reduction to homozygosity for the mutated WT1 allele. Our results provide evidence of a direct role for WT1 in Denys-Drash syndrome and thus urogenital system development.
Renal biopsy specimens of 40 patients with recent-onset insulin-dependent diabetes mellitus treated with cyclosporine (CSA) for 6-29 months were examined. Cyclosporine-associated chronic vascular interstitial toxicity of moderate intensity was found in 10 patients (25%). The most prominent lesions were interstitial fibrosis and tubular atrophy. Arteriolopathy was less pronounced and glomerular damage unremarkable. A significant correlation exists between the extent of tubular atrophy and CSA trough whole blood levels. These data indicate that the development of CSA-associated chronic nephropathy is dose-dependent.
Cyclosporin A (CyA, Sandimmun) was given to 71 children with idiopathic nephrotic syndrome, 45 of whom were steroid-dependent with signs of steroid toxicity, and 23 who were steroid-resistant. Cyclosporin A was effective in 80% of the steroid-dependent patients, allowing cessation of corticosteroid treatment. However, most of these patients relapsed when CyA was tapered or withdrawn. In these patients, CyA may be required for long periods of time. Conversely, CyA was less effective in steroid-resistant patients; only 7% achieved remission with CyA alone. Cyclosporin A in association with prednisone may be an effective alternative as 8 out of 14 patients entered remission with this treatment combination. Serial renal biopsies were performed in 43 patients to evaluate the potential nephrotoxicity of the treatment. Eighteen patients developed significant tubulointerstitial lesions which were attributable to CyA nephrotoxicity. The risk of developing chronic nephrotoxicity appears to be higher in steroid-resistant patients, and was not related to the duration of treatment. Cyclosporin A nephrotoxicity can develop in patients with normal renal function.
A clinicopathologic study of 41 biopsy specimens from renal grafts transplanted at least ten years earlier showed normal findings or only mild tubulointerstitial lesions in 63% of cases. Results confirmed the good prognostic value of renal graft biopsy performed ten years after transplantation. A very close correlation was demonstrated between histologic evidence of chronic rejection (interstitial fibrosis, tubular atrophy, and fibrous endarteritis) and long-term graft outcome. Severity of interstitial fibrosis was apparently a more reliable indicator of prognosis than severity of fibrous endarteritis. Among 16 patients with a history of acute rejection, none had residual parenchymatous lesions. In contrast, among patients with major tubulointerstitial and/or vascular lesions, most had previously experienced one or several episodes of acute rejection. Evidence of allograft glomerulopathy was seen in approximately one case in four (11 patients). Among these patients, only eight had proteinuria and only four lost their graft. Among the four patients who developed recurrent membranoproliferative glomerulonephritis (type I in three cases and type II in one case), three lost the deposits previously detected by immunofluorescence, probably as a result of immunosuppressive therapy.
Clinical and biological features, histologic findings, and outcome were studied in 32 children with systemic lupus erythematosus who underwent at least two renal biopsies during the course of their disease. Results showed that renal biopsy was a useful aid for therapy in that it demonstrated the presence or absence of disease activity, but was unhelpful for predicting the long term outcome. Repeat renal biopsies proved an excellent means for monitoring the course of the nephropathy. This study showed that the various patterns of glomerulonephritis seen in SLE may exhibit changes over time, with either improvement or progression. Regression of lesions was seen mainly after treatment, whereas progression was associated with renal or extrarenal exacerbations of the disease. The absence of clinical improvement may reflect transformation to histologic forms which are unresponsive to therapy.
Thirty of 85 children with membranous glomerulonephritis (MGN) had associated extraglomerular disorders. The relation of these associations to membranous glomerulonephritis (MGN) is discussed. The causal relationship of acute hepatitis (5 cases), persistent hepatitis B antigenemia (6 cases), systemic lupus erythematosus (2 cases) and syphilis (1 case) may be ascertained; in similar conditions a definite antigen (Ag) has been found in MGN deposits. The association with SS or SA hemoglobinopathy (3 cases) ans with a preceding streptococcal infection (4 cases) raises the possible responsibility of renal tubular epithelium (RTE) Ag and of a streptococcal Ag. D-penicillamine therapy (1 case) is a well-known cause of MGN although the acting Ag remains unknown. Four children had serum sickness-like symptoms, two had hematologic disorders and two had proximal tubular dysfunction, one of them with proven anti-tubular and anti-alveolar basement membrane antibodies. A decrease in plasma C4, Clq, and factor B with normal C3 was frequently observed. The multiple Ag previously described as causative of MGN are recalled. The prevalent incidence of HBsAg is stressed, and the necessity for further investigations in patients with MGN in order to find an underlying disease is emphasized.
14 children with proven or presumably immunologically mediated tubulo-interstitial nephritis are presented. In 2 patients anti-tubular basement membrane antibodies were detected. In 6 immunofluorescence microscopy showed granular deposits of immunoglobulin and/or complement likely representing interstitial location of immune complexes. The findings by immunofluorescence were not significant in the remaining 6 patients. However, the association of renal disease to extra-renal disorders, namely chronic active hepatitis and ulcerative colitis, or uveitis or the presence of an epithelioid granuloma with multinucleated giant cells suggests that in such patients an immunologic disorder might be responsible for the tubulo-interstitial nephritis.
The wide utilization of renal biopsy and the introduction of electron microscopic and immunohistologic methods has allowed better definition of the clinico-pathological conditions associated with the nephrotic syndrome (NS). Two major categories of facts can be differentiated. In the first one, diffuse lesions of glomeruli, either secondary to specific diseases, or apparently primary diseases such as membranous or membrano-proliferative glomerulonephropathy (GN) are responsible for the increased permeability of the glomerular capillaries. In most of these, there is evidence that immunological mechanisms play a role in the injury of the glomerular capillary. Any of the following clinical symptoms are suggestive of this category of NS: an acute nephritic onset, a moderate NS, macroscopic hematuria, marked hypertension and/or renal insufficiency, poorly selective proteinuria and decreased plasma C3 levels. Patients affected with any of these glomerulopathies usually do not respond to steroids. In the second one, usually referred to as the idiopathic nephrotic syndrome (INS) the mechanism of glomerular capillary alteration is unknown and the nephrotic syndrome is more marked. Minimal change NS (MCNS) accounts for the great majority of INS and is characterized in most cases by a selective proteinuria, the absence of hematuria, a good response to steroids and a good prognosis. However, in some instances, renal biopsy reveals either diffuse mesangial proliferation (DMP) or focal glomerular sclerosis (which may be superimposed on MCNS or on DMP). In both instances, hematuria may be present and 50--75% of patients do not respond to steroids and have a poor prognosis. There is still considerable controversy about the exact relationship between these 3 patterns. We believe that they are not distinct entities but represent variants of the same disease. In addition to these 2 major categories of NS, there are, in infancy, 2 conditions associated with a NS of poor prognosis: congenital NS of Finnish type and infantile mesangial sclerosis. Since steroid-sensitive nephrosis is by far the commonest cause of NS especially in young children up to 8 years, a renal biopsy should be performed only in 2 instances: (a) when the clinical symptoms suggest diffuse glomerular lesions, and (b) when steroid resistance has been demonstrated.
A study of complement profiles and of "nephritic activity" (NeF activity) has been carried out in 33 children presenting with membranoproliferative glomerulonephritis (MPGN), in order to determine the pathway of complement activation. By morphological studies two varieties of MPGN have been distinguished. In MPGN with subendothelial deposits, immunofluorescent studies and complement profiles show an activation by the classical pathway. The demonstration of NeF activity in 7 of 20 patients suggests that there is recruitment of the amplification pathway. In MPGN with dense deposits, immunopathological studies indicate an activation of the complement system through the alternate pathway, NeF activity being present in 10 of 13 patients. With the functional tests used, it is not possible to ascertain that the factors responsible for the NeF activity in MPGN with subendothelial deposits are identical to the C3NeF identified in MPGN with dense deposits and/or partial lipodystrophy.
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The renal biopsy of a 3-year old boy with complete Fanconi syndrome showed the association of a membranous glomerulonephritis with severe tubulointerstial changes. Immunofluorescence microscopy disclosed linear and granular deposits of Ig along tubular basement membranes. The presence of anti-tubular basement membrane antibodies in the patient's serum was demonstrated by indirect immunofluorescence and radioimmunoassay. The child also developed pulmonary involvement associated with episodes of acute anemia. Anti-alveolar basement membrane antibodies were detected by indirect immunofluorescence. The present case is the first reported example of auto-immune disease characterized by the presence of anti-tubular and alveolar basement membrane antibodies associated with an immune complex glomerulonephritis.
The prognostic significance of the finding of diffuse mesangial proliferation (DMP) in patients presenting with idiopathic nephrotic syndrome (INS) has not been well established. The clinical course, therapeutic response and final outcome of 38 patients in whom renal biopsy showed DMP are reported. They have been subdivided into 2 groups according to the absence (18 patients: group I) or presence (20 patients: group II) of superimposed lesions of focal and segmental sclerosis and/or hyalinosis (FSS/H). Clinical presentation was similar in both groups although patients in group I were less severely affected. Non of the patients of group II responded to corticosteroids, whereas in group I 2/16 responded and 2 infants remitted without treatment. At the latest assessment, 5/18 patients in group I and 10/20 in group II had progressed to terminal renal failure or had impaired renal function. Five patients in group I and 3 in group II were in clinical remission. Eight of 11 repeat biopsies performed in patients of group I showed the development of FSS/H. Thus patients with DMP seem prone to develop lesions of FSS/H. Their course if often worse than that of minimal change with FSS/H since 7 of the 10 patients who developed renal failure did so within 3 years of onset. The finding of DMP in a patient with idiopathic nephrotic syndrome is usually but not invariably an ominous feature.
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