Germline and somatic mutations in the tyrosine kinase domain of the MET proto-oncogene in papillary renal carcinomas

Hereditary papillary renal carcinoma (HPRC) is a recently recognized form of inherited kidney cancer characterized by a predisposition to develop multiple, bilateral papillary renal tumours. The pattern of inheritance of HPRC is consistent with autosomal dominant transmission with reduced penetrance. HPRC is histologically and genetically distinct from two other causes of inherited renal carcinoma, von Hippel-Lindau disease (VHL) and the chromosome translocation (3;8). Malignant papillary renal carcinomas are characterized by trisomy of chromosomes 7, 16 and 17, and in men, by loss of the Y chromosome. Inherited and sporadic clear cell renal carcinomas are characterized by inactivation of both copies of the VHL gene by mutation, and/or by hypermethylation. We found that the HPRC gene was located at chromosome 7q31.1-34 in a 27-centimorgan (cM) interval between D7S496 and D7S1837. We identified missense mutations located in the tyrosine kinase domain of the MET gene in the germline of affected members of HPRC families and in a subset of sporadic papillary renal carcinomas. Three mutations in the MET gene are located in codons that are homologous to those in c-kit and RET, proto-oncogenes that are targets of naturally-occurring mutations. The results suggest that missense mutations located in the MET proto-oncogene lead to constitutive activation of the MET protein and papillary renal carcinomas.

Polyarteritis nodosa clinically masquerading as temporal arteritis with lymphadenopathy

We describe a patient with biopsy proven polyarteritis nodosa who presented with headache, scalp tenderness and lymphadenopathy. This case illustrates the need to be wary of conditions mimicking temporal arteritis.

A controlled study of dimethyl sulfoxide in interstitial cystitis

To evaluate the effectiveness of dimethyl sulfoxide in the treatment of patients with biopsies suggestive of interstitial cystitis, 33 patients underwent a controlled crossover trial. Patients were allocated randomly to receive 50 per cent dimethyl sulfoxide or placebo (saline). The medication was administered intravesically every 2 weeks for 2 sessions of 4 treatments each. Response was assessed urodynamically and symptomatically. Thirty women and 3 men (mean age 48 years and mean duration of symptoms 5.5 years) were entered into the study. No significant side effects to dimethyl sulfoxide were noted. When assessed subjectively, 53 per cent of dimethyl sulfoxide treated patients were markedly improved compared to 18 per cent of the placebo treated patients. Of the dimethyl sulfoxide group 93 per cent had objective improvement versus 35 per cent of the placebo group. Thus, dimethyl sulfoxide proved to be superior to placebo in the objective and subjective improvement of patients with interstitial cystitis.

Increased mast cells of the bladder in suspected cases of interstitial cystitis: a possible disease marker

Mast cells reportedly have been increased in the detrusor muscle bundles of the bladder in patients with interstitial cystitis. In 30 patients with suspected interstitial cystitis quantification of mast cells within the muscularis and submucosa was done. The results were compared to those obtained from a variety of normal bladder specimens removed surgically (16 specimens) and at autopsy (15), and from bladders with a variety of miscellaneous inflammatory conditions (20). In patients with suspected interstitial cystitis the number of mast cells was increased significantly (p less than 0.001) compared to the 3 control groups. This finding suggests that quantification of mast cells in the muscularis may be a useful marker in the histopathological evaluation of bladder biopsies in patients with suspected interstitial cystitis.

Enhanced expression of class I major histocompatibility complex gene (Dk) products on immunogenic variants of a spontaneous murine carcinoma

Both immunogenic and nonimmunogenic variant clones were isolated from a recently obtained spontaneous murine adenocarcinoma after treatment (xenogenization) with either the mutagen ethyl methanesulfonate or the DNA hypomethylating agent, and "gene activator," 5-azacytidine. Clonal analysis of the untreated tumor population confirmed that immunogenic variants arose as a consequence of the xenogenization protocol. At a dose of 10(6) cells per mouse, nonimmunogenic variants, like the parental tumor line, grew progressively in normal syngeneic recipients. In contrast, immunogenic variants were rejected in normal syngeneic mice and grew progressively only in T-cell-deficient nude mice. Serologic analysis of the respective clonal variants revealed that immunogenic variants expressed substantially elevated (fourfold to tenfold) levels of class I H-2Dk antigen relative to parental or nonimmunogenic cell lines. Two variants exhibiting marginal immunogenicity expressed high and low levels of major histocompatibility complex (MHC) antigen, respectively suggesting that elevated MHC expression, although possibly a contributing factor, did not account for the immunogenic phenotype in all cases. Finally, the immunogenic phenotype of two variants decayed with time in culture. Clones in the process of reversion lost their elevated Dk gene expression and became progressively more tumorigenic in normal syngeneic mice. Together, these data are consistent with a hypothesis that elevated MHC expression can contribute to the immunogenic phenotype of originally low MHC-expressing tumors and that the reduced level of MHC observed in certain clinical cancers may have significant implications with regard to immunologic aspects of the tumor-host relationship.

Active and chronic phases of Berger's disease (IgA nephropathy)

Berger's disease, or IgA nephropathy, is generally considered as pursuing a chronic course, often with recurrent attacks of gross hematuria or persistent microscopic hematuria. However, little attention has been paid to the acute changes that may accompany this nephropathy, and there are few reports of follow-up renal biopsy studies in these patients. We have had the opportunity to study two patients with Berger's disease (IgA nephropathy) in whom initial and follow-up renal biopsy studies were available. Both of these patients presented clinically with gross hematuria and moderately heavy proteinuria. In both cases, the initial renal biopsy disclosed diffuse mesangial proliferation associated with crescent formation, while follow-up biopsy disclosed only mild mesangial proliferation and no crescents. In one case electron microscopy revealed prominent subendothelial and small mesangial deposits in the initial biopsy, which became almost solely large mesangial in the second biopsy. The other case demonstrated only mesangial deposits in both biopsies.