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Biomedical subjects

G Touchard

Publications and source records attributed to G Touchard.

At least 37 records · Page 2Linked to original sources
PubMed1997

High prevalence and usual persistence of serum monoclonal immunoglobulins evidenced by sensitive methods in renal transplant recipients.

BACKGROUND: The occurrence of serum monoclonal immunoglobulins in kidney transplant recipients is well known but their significance and predictive value for the occurrence of lymphoma are a matter of debate. We therefore conducted a study of monoclonal immunoglobulins by a sensitive method during the long-term follow up of grafted patients. METHODS: Monoclonal immunoglobulins were characterized by high-resolution electrophoresis, conventional immunoelectrophoretic analysis, and a sensitive Western blotting procedure in the serum from 84 renal transplant recipients prior to grafting and subsequently, with a 1-8-year follow-up and excluding the patients who developed posttransplant lymphoma. RESULTS: Low abundance monoclonal immunoglobulins were detectable prior to transplantation in 56 cases (66.6%) and after graft in 72 cases (85.5%) (and in 1 case (1.2%) and 18 cases (21.4%) of cases respectively, by immunoelectrophoresis). These abnormalities were often multiple in individual sera. Monoclonal components detected by immunoblotting were transient in 23.8% of patients only (whereas those evidenced by immunoelectrophoresis usually became undetectable by this method) and their pattern was remarkably stable in the majority of cases. The frequency of post-transplant monoclonal immunoglobulins was higher in patients of more than 50 years of age than in younger patients. The appearance of monoclonal components after grafting and their transient character correlated with CMV infections. No correlation was found with various other parameters. The isotypic distribution of monoclonal immunoglobulins with an IgM, IgG3, and IgG1 predominance and an abnormally low kappa/lambda ratio was the same as that observed in various immunodeficiency states. The monoclonal immunoglobulin pattern in three further patients who developed post-transplant lymphoma was unremarkable. CONCLUSION: Monoclonal immunoglobulins hence are not discriminant for lymphoma and their characterization does not appear to be necessary in the evaluation of followed up grafted patients, at least for a prediction of post-transplant lymphoma.

Adolescent↗
PubMed1997

Maintenance cyclosporin monotherapy after renal transplantation--clinical predictors of long-term outcome.

BACKGROUND: There is considerable debate about whether maintenance cyclosporin (CsA) monotherapy is advisable or not in renal transplantation. METHODS: Between August 1984 and December 1989, 463 adult patients received a first cadaver graft. Initial immunosuppression was sequential: antilymphocyte or antithymocyte globulins (10-14 days), prednisone and azathioprine were combined and CsA was introduced (6-8 mg/kg/day) when the antilymphocyte or antithymocyte globulins were discontinued. When the graft function was stable and the peak of preformed lymphocytotoxic antibodies was < or = 25% and/or the number of rejection episodes was < or = 1, the steroid therapy was stopped within 1.5-3 months after transplantation, and azathioprine within 3-12 months. Patients with both anti HLA antibodies > 25% and more than one rejection episode were excluded. Cyclosporin doses were adapted for whole-blood trough levels between 100 and 200 ng/ml (monoclonal antibody radioimmunoassay or high-performance liquid chromatography). Cyclosporin monotherapy was attempted in 234 of the 463 patients. RESULTS: At the end of the investigation in January 1993 (follow-up time > 36 months, mean 60.5 +/- 4.5 months), 135 patients were receiving CsA without steroids or azathioprine. The 99 CsA monotherapy failures were due to rejection episodes in 48 cases, CsA A nephrotoxicity in 26 cases, and other causes in 25 cases, including five deaths and four with poor compliance. Renal function was stable in patients with successful CsA monotherapy: mean creatininaemia was 124 +/- 10 mumol/l at the time of CsA monotherapy inclusion and 129 +/- 10 mumol/l at the end of follow-up (mean time of CsA monotherapy 52 +/- 6 months). The parameters for predicting monotherapy success were age (43.2 versus 37.8. P = 0.0014), timing of trial inclusion > or = 6 months post-transplant (7.9 +/- 3 versus 5.3 +/- 3.1 months, P = 0.04), and excellent and stable renal function at the time of inclusion (124 +/- 10 versus 145 +/- 32 mumol/l, P < 0.001). CONCLUSIONS: Maintenance CsA monotherapy was effective in 58% of low-immunological-risk first-graft patients and probably did not jeopardize overall results of our first grafts: patient and graft survival were respectively 90 and 73% at 6 years. We propose this policy to avoid long-term complications of glucocorticoid and azathioprine in selected compliant recipients with low immunological risk, follow-up time post-transplantation > 6 months, and stable creatininaemia levels.

Adult↗
PubMed1997

Cast nephropathy in mu heavy chain disease.

The occurrence of kidney diseases was very rarely reported in heavy chain diseases (HCD). At variance with gamma and alpha HCD in which there is no free light chain secretion, about two-thirds of mu HCD patients have urinary Bence Jones (BJ) proteins. We report on a 66 year-old man affected with typical mu HCD who developed renal failure after a 3-year follow-up. He had presented with chronic lymphocytic leukemia with bone marrow vacuolated plasma cells, serum mu HCD protein and serum and urine BJ protein. After an apparent hematological remission following fludarabine therapy, anemia and blood hyperlymphocytosis recurred together with microscopic hematuria, proteinuria and increased creatininemia. Kidney biopsy showed numerous tubular eosinophilic casts which stained for kappa chain determinants by immunofluorescence and an interstitial infiltration by lymphocytes and plasma cells. The hematological and renal condition improved after reinitiation of chemotherapy. This appears to be the first documented report of a light chain-dependent visceral complication in HCD.

Aged↗
PubMed1996

[Digital necrosis associated with fenoxazoline poisoning. Apropos of a case and review of the literature].

We report the case of a 53 year-old woman with paroxystic hypertension and digital ischemia. The only triggering factor was chronic intoxication by a nasal vasoconstrictor:fenoxazoline. The worsening of the lesions required amputation of the third phalanx of the 3rd and 5th finger and the pulp of the 4th finger of the left hand. The review of literature exhibits association between fenoxazoline intoxication and paroxystic hypertension, myocardial ischemia or stroke, but association between fenoxazoline intoxication and digital ischemia has never been reported. We emphasize the extreme caution necessary with the prescription and the chronic consumption of this kind of drug.

Female↗
PubMed1996

Renal involvement in Behçet's disease. Case report and review of the literature.

A female patient has suffered from Behçet's disease (BD) for 15 years. During one recurrent episode proteinuria and microscopic hematuria were discovered. Renal biopsy revealed focal segmental glomerulopathy with IgA deposits. Renal involvement in BD is uncommon and includes amyloidosis, crescentic glomerulonephritis and IgA nephropathy. BD is a cause of secondary IgA nephropathy. Immunologic features of the two diseases, particularly increased serum IgA, are reviewed.

Behcet Syndrome↗
PubMed1995

Role of light chain variable region in myeloma with light chain deposition disease: evidence from an experimental model.

Light chain deposition disease (LCDD) results from a propensity of some human monoclonal L chains to form tissue deposits. We designed an experimental model for in vivo expression of human kappa L chain sequences in mice and compared a somatically mutated LCDD chain with a closely related control kappa chain, both encoded by the unique V kappa IV gene. Mice secreting the LCDD chain but not those producing the control chain showed deposits with a distribution similar to that observed in patients. These data show that discrete changes in V region sequences can play a major role in tissue deposition of human L chains.

Amino Acid Sequence↗
PubMed1995

Sequences of V kappa L subgroup light chains in Fanconi's syndrome. Light chain V region gene usage restriction and peculiarities in myeloma-associated Fanconi's syndrome.

Certain monoclonal Ig light chains (LC) are responsible for marked disturbances of proximal tubule cell functions (Fanconi's syndrome, FS). In patients with FS, intracellular crystal-like inclusions containing LC determinants are commonly found in plasma cells, macrophages, and renal tubular cells. In an attempt at understanding the pathogenesis of myeloma-associated FS, we recently determined the first complete primary sequence of a kappa-LC (CHEB) responsible for the disease. We now report on the primary structure of three other kappa-LC of the V kappa l variability subgroup associated with FS (TRE, TRO, and DEL). After PCR amplification, cDNA encoding these LC were sequenced. CHEB, TRE, and TRO LC genes were found to be highly homologous to the same germline gene O2/O12. These patients had numerous intracellular crystals, whereas the fourth patient, DEL, had no detectable crystals. The LC from the latter patient was homologous to another germline gene, O8/O18. Comparison of these LC sequences to previously reported LC of the V kappa l subgroup allowed identification of a number of unusual amino acid substitutions in the V region that had rarely or never been previously described at the corresponding positions. Some of these unusual substitutions affect highly conserved amino acids located either in an external loop (residue 30) or in inner (residues 48 and 55) and outer (positions 63 and 72) beta-sheets that may be important for the structure and binding properties of the kappa-chains. These and several other substitutions, some of them shared with amyloidogenic kappa-LC, could induce conformational alterations and represent a determinant pathogenic factor.

Amino Acid Sequence↗
PubMed1995

Protease resistance and binding of Ig light chains in myeloma-associated tubulopathies.

Kidney tubule dysfunction and lesions are frequent complications of myeloma, related to unknown properties of the monoclonal light chain. We have analyzed protease sensitivity and binding properties of urinary light chains from four patients with Fanconi's syndrome, 12 with cast nephropathy, and four control patients without myeloma-associated tubulopathy. All light chains were normal-sized, monomeric and/or dimeric, and none was N-glycosylated. Kinetic studies of light chain digestion by pepsin and the lysosomal enzyme cathepsin B showed the generation of a protease-resistant 12 kDa fragment, corresponding to the V domain of the kappa chain in the four Fanconi's syndrome patients; in two out of four the V domain was also completely resistant to trypsin. Western and dot blots revealed similar patterns of reactivity of light chains from patients with the Fanconi's syndrome towards other light chains. Properties of cast-nephropathy light chains were more heterogeneous but clearly differed from those of Fanconi's syndrome: (i) 9 out of 12 were of the lambda-type; (ii) only four yielded a transient 12 kDa fragment after cathepsin B digestion, but all showed some resistance to proteolysis of the entire molecule or a fragment thereof to at least one protease, at variance with control light chains; (iii) they displayed various patterns of reactivity with other light chains; (iv) 7 out of 12 reacted specifically with Tamm-Horsfall protein (THP) by ELISA, in contrast with those of Fanconi's syndrome. In one patient who presented with cast nephropathy and the Fanconi's syndrome, the light chain exhibited both partial resistance of the V kappa domain to cathepsin B and the highest reactivity with THP.(ABSTRACT TRUNCATED AT 250 WORDS)

Adjuvants, Immunologic↗
PubMed1995

Renal involvement in hematological disorders: monoclonal immunoglobulins and nephropathy.

The study of monoclonal immunoglobulin-associated nephropathies is useful for analyzing the physicochemical properties of immunoglobulin components responsible for their deposition in the kidney. Notable advances include the first description of truncated heavy-chain deposition disease, characterization of protease resistance and binding properties of immunoglobulin light chains involved in myeloma-associated Fanconi's syndrome and cast nephropathy, and identification of hepatitis C virus as a plausible causative agent of the so-called essential mixed cryoglobulinemias.

Antibodies, Monoclonal↗
PubMed1994

A kidney biopsy is clearly mandatory to confirm the indication of plasma exchanges in adult haemolytic uraemic syndrome.

In case of haemolytic uraemic syndrome, it is not always possible to identify on a pure clinical basis the different kidney lesions responsible for the syndrome. We report a series of six cases without thrombotic microangiopathy, which emphasizes the need to perform a kidney biopsy as early as possible, so as to confirm the actual usefulness of plasma exchanges (PE) commonly carried out in emergency in every case of adult haemolytic uraemic syndrome. PATIENTS AND METHODS--Files of patients who were treated for haemolytic uraemic syndrome over the past 14 years were reviewed. Patients in whom thrombotic microangiopathy had been excluded by renal histology data were studied. Every patient was promptly treated with hypotensive drugs, so as to obtain blood pressure levels not exceeding 160-90 mmHg. Dialysis was performed in two patients. Daily PE with fresh frozen plasma were carried out in three patients as early as the first 24 hours after admission, and discontinued immediately after thrombotic microangiopathy could be excluded. RESULTS--All the patients met the usual criteria for diagnosis of haemolytic uraemic syndrome. Elevated liver enzymes were also found in the four cases of preeclampsia, consisting with diagnosis of severe HELLP syndrome. One case was associated with oestrogen therapy. Glomerular lesions were seen in four patients: slight endotheliosis in three cases of preeclampsia; marked lesions of IgA mesangial deposits in the patient who had been treated by contraceptive pill. Three patients had acute tubular necrosis and three had intense lesions of nephrosclerosis. Complete remission was obtained in every case of preeclampsia. Renal failure persisted in two cases (IgA glomerulopathy and one case of nephrosclerosis). DISCUSSION--The histological heterogeneity of haemolytic uraemic syndrome has been already well demonstrated. Typical lesions of thrombotic microangiopathy are usually classified into predominant glomerular lesions, pure arteriolar and mixed lesions. In other cases, thrombotic microangiopathy is not found: kidney lesions may be glomerular (endotheliosis, various subtypes of glomerulonephritis), tubular (acute tubular necrosis) or vascular (nephroangiosclerosis). In every aetiological circumstance, several different lesions may be found together. The usefulness of PE has been proved in thrombotic thrombocytopenic purpura, has been suggested in haemolytic uraemic syndrome and to a lesser extent in persistently severe HELLP syndrome. Unfortunately, none of these reports gave any information about kidney lesions responsible of acute renal failure. CONCLUSION--The haemolytic uraemic syndrome is a syndrome: thrombotic microangiopathy has to be proven when treatment by PE is planned, except in some severe clinical circumstances.

Adult↗