The GAP-related domain of tuberin, the product of the TSC2 gene, is a target for missense mutations in tuberous sclerosis

Tuberous sclerosis is an autosomal dominant trait in which the dysregulation of cellular proliferation and differentiation results in the development of hamartomatous growths in many organs. The TSC2 gene is one of two genes determining tuberous sclerosis. Inactivating germline mutations of TSC2 in patients with tuberous sclerosis and somatic loss of heterozygosity at the TSC2 locus in the associated hamartomas indicate that TSC2 functions as a tumour suppressor gene and that loss of function is critical to expression of the tuberous sclerosis phenotype. The TSC2 product, tuberin, has a region of homology with the GTPase activating protein rap1GAP and stimulates the GTPase activity of rap1a and rab5a in vitro. Here we show that the region of homology between tuberin and human rap1GAP and the murine GAP mSpa1 is more extensive than previously reported and spans approximately 160 amino acid residues encoded within exons 34-38 of the TSC2 gene. Single strand conformation polymorphism analysis of these exons in 173 unrelated patients with tuberous sclerosis and direct sequencing of variant conformers together with study of additional family members enabled characterisation of disease associated mutations in 14 cases. Missense mutations, which occurred in exons 36, 37 and 38 were identified in eight cases, four of whom shared the same recurrent change P1675L. Each of the five different missense mutations identified was shown to occur de novo in at least one sporadic case of tuberous sclerosis. The high proportion of missense mutations detected in the region of the TSC2 gene encoding the GAP-related domain supports its key role in the regulation of cellular growth.      

Cytogenetic studies of adipose tissue tumors. II. Recurrent reciprocal translocation t(12;16)(q13;p11) in myxoid liposarcomas

Detailed chromosome studies, briefly reported previously, from short-term cultures of tumor cells from myxoid liposarcomas are reported. A common reciprocal translocation, t(12;16)(q13;p11), was found in three cases and a complex t(1;12;16)(p11;q13;p11) in the fourth one. This nonrandom primary change, not described before in solid tumors, could characterize the myxoid form of liposarcoma. The involvement of a closely located breakpoint on chromosome #12 in a reciprocal t(3;12)(q28;q14) described in a lipoma in the previous article of this series, suggests a common basis in the biological process of proliferation of tumors sharing a common histogenesis.     

Glycoproteins present in human follicular fluid that inhibit the zona- binding capacity of spermatozoa

Previous studies have suggested that human follicular fluid contains factors that reduce the zona-binding capacity of spermatozoa. The present study provides further evidence of the existence of such factors. Using the hemizona binding assay (HZA), we have shown that the inhibitory effect of human follicular fluid on the zona-binding capacity of spermatozoa is concentration-dependent, an inhibitory effect being detected when the concentration of human follicular fluid was > or = 10%. A 1% concentration of human follicular fluid did not possess this inhibitory activity. Heating human follicular fluid at 56 degrees C for 30 min did not affect its inhibitory properties; treatment with proteinase-K abolished such inhibition. Human follicular fluid was fractionated sequentially by concanavalin-A affinity chromatography, Mono Q ion-exchange chromatography and Superose-12 gel filtration. The zona binding inhibitory activity resided in the fraction which bound to the lectin and Mono Q column and contained molecules with native molecular weights of 32 and 192 kDa. Sodium dodecyl sulphate-polyacrylamide gel electrophoresis analysis suggested that the 192 kDa glycoprotein was a tetramer, while the 32 kDa glycoprotein remained as a single molecular species under denaturing conditions. We conclude that two glycoproteins were responsible for the zona binding inhibitory activity of human follicular fluid. The physiological role of these factors remains unclear.      

Chromosome changes in metastatic human melanoma

Cytogenetic studies were performed on human malignant melanoma cells from eight metastatic lesions. Five tumors displayed near-triploid and three near-diploid chromosome numbers. Chromosomes #1,#6,#7, followed by #2 and #9, were found to be most frequently involved in structural aberrations. Aberrations involving chromosome #1, with deletions or translocations of 1p, involving region 1p12-1p22 in seven of eight breakpoints of the p arm were observed. Seven of nine breakpoints of 6q were located at region 6q15-6q21. Most of the breakpoints on chromosome #7 occurred near the centromeric region. All tumors had additional chromosome material involving 1q, chromosome #7 (7q in two tumors), and in five tumors an increased dose of chromosome #6 (6p in one tumor). The nonrandom breakpoints of these and other chromosomes involved diverse bands, including loci of oncogenes and fragile sites. The observation of nonrandom chromosomal changes in advanced malignant melanoma suggests that genes important in the progression of melanoma are located on chromosomes #1,#6, and #7.     

Patterns of contrast enhancement of benign and malignant hepatic neoplasms during bolus dynamic and delayed CT

Bolus dynamic and delayed computed tomographic (CT) scans of the liver were evaluated in 43 patients with 54 hepatic hemangiomas and 111 patients with primary or secondary malignant hepatic neoplasms. Twelve patterns of contrast enhancement were recognized during the bolus dynamic phase and delayed scanning. A "typical" CT pattern for hemangiomas (present in 29 of 54 hemangiomas [53.7%]) was established: (a) diminished attenuation prior to intravenous contrast medium administration (excluding lesions arising in a liver with diffuse fatty infiltration), (b) peripheral contrast enhancement during the bolus dynamic phase, and (c) complete isodense fill-in on delayed scan images. Using these criteria, we distinguished hemangiomas from malignant neoplasms in most patients. Only one of 63 (1.6%) malignant neoplasms manifested these typical CT criteria of hemangioma. There is an 86% chance that a lesion with the typical CT appearance of hemangioma is actually a hemangioma, even when found in a patient with a known nonhepatic primary neoplasm.     

Plasminogen activators in human malignant melanoma

Metastatic malignant melanomas from 16 patients, extracted with Triton X-100, were analyzed for plasminogen activator activity by azocaseinolysis . In 6 cases tumor explants were set up also in short-term organ culture, and the rate of plasminogen activator secretion into the culture medium was determined. Both the extractable activator content [8.66 +/- 7.8 "Committee on Thrombolytic Agents" (CTA) U/g tissue] and the activator secretion rates (0.90 +/- 1.6 CTA U/g/hr) were low in comparison with values for other human tumors. In addition to the activity, the type of plasminogen activator also was determined by immunoinhibition with goat antihuman urokinase antibody in the azocaseinolytic assay, as well as by sodium dodecyl sulfate (SDS) gel electrophoresis followed by zymography on fibrin-agar, in the presence and absence of antibody. On the average, 77% of the activator activity was of the urokinase type in the extracts, and 90% in the culture fluids. Immunoperoxidase reaction for the detection of urokinase showed this enzyme to be localized mainly in the cell membrane of the melanoma cells; stromal elements showed no specific staining. These results are of interest in view of the findings made recently by investigators in several laboratories that in all but one of the melanoma cell cultures derived from metastatic human tumors, only the vascular type ("tissue activator") was cell associated or was secreted into the culture medium. The possible reasons for this discrepancy are discussed.     

Do microscopic surgical margins matter for primary gastric gastrointestinal stromal tumor?

BackgroundAlthough tumor size and mitotic rate are established prognostic factors for worse survival in patients undergoing surgical resection for gastric gastrointestinal stromal tumors, the impact of microscopic margins, or R1 resection, is not completely established.MethodsPatients who received no neoadjuvant therapy and underwent surgical resection for stage I to III gastric gastrointestinal stromal tumors were identified from the 2010 to 2013 National Cancer Database and divided into 2 cohorts, R0 and R1 resections. Cox proportional hazards ratio and Kaplan Meier survival estimates were utilized to analyze 5-y overall survival.ResultsOf 2,084 patients, those with R1 resection (57, 2.7%) were more likely to have tumors >10 cm (28.1% vs 11.9%, odds ratio 3.51, P = .017) and stage III disease (26.3% vs 11.2%, odds ratio 2.26, P = .047). Although margin status was associated with higher risk tumors, it was not associated with receipt of adjuvant therapy. After multivariate Cox regression, R1 and R0 patients did not have a difference in 5-y overall survival (82.5% vs 88.6%, hazards ratio 1.26, P = .49). When stratified by stage of disease, there remained no difference in survival across all stages when comparing R1 and R0 patients.ConclusionPositive microscopic margins are uncommon but do not appear to impact survival outcomes in patients with resected localized gastric gastrointestinal stromal tumors.     

NEW SUSPENSION DEVICE FOR LARYNGEAL ENDOSCOPIC PROCEDURES

In view of the economic constraints in acquiring sophisticated equipments in service hospitals, a new suspension device for endolaryngeal surgery using anaesthetic laryngoscope and routinely available tonsillectomy instruments has been developed. This device is a modification of Ijadoula''s suspension laryngoscope.KEY WORDS: Suspension laryngoscope, Laryngeal endoscopy     

Der(16)T(1-16) is a nonrandom secondary chromosome aberration in many types of human neoplasia, including myxoid liposarcoma, rhabdomyosarcoma and Philadelphia-chromosome-positive acute lymphoblastic-leukemia

An unbalanced translocation between chromosomes 1 and 16, der(16)t(1;16), resulting in trisomy 1q and loss of genetic material from 16q, has been thus far suggested to constitute a nonrandom secondary abnormality in two types of closely related solid tumors - Ewing sarcoma and peripheral primitive neuroepithelial tumor (PNET). We report on three cases of soft tissue tumors, a myxoid liposarcoma, a PNET and a rhabdomyosarcoma, and four cases of hematologic disorders, two acute lymphoblastic leukemias (ALL), an acute mixed leukemia and a refractory anemia, that in addition to primary chromosome abnormalities displayed the presence of the der(16)t(1;16). All three cases of acute leukemia were Philadelphia (Ph) chromosome-positive and all displayed both lymphoid and myeloid antigens. Our results and review of the literature indicate that the occurrence of der(16)t(1;16) is not limited to Ewing sarcoma and PNET, but that acquisition of this abnormality may represent a more general pathway of clonal evolution in several different tumor types including Ph chromosome-positive ALL, myxoid liposarcoma, rhabdomyosarcoma, breast cancer, endometrial adenocarcinoma, myelodysplastic syndromes, acute myeloid leukemia, retinoblastoma, and Wilms' tumor.     

Prognostic factors in malignant melanoma patients with solitary or multiple brain metastases. Is there a role for surgery?

BACKGROUND: The aim of this study is to evaluate the prognostic parameters and treatment modalities of malignant melanoma patients with brain metastases. METHODS: Experimental design: a retrospective study with a mean follow-up of 46 months. Setting: specialized Cancer Center. Patients: the charts of 136 patients, treated in Roswell Park Cancer Institute, for melanoma brain metastases, were analyzed. Interventions: all patients were treated surgically and in the majority adjuvant therapy was applied. Measures: survival and time of recurrence of patients and possible prognostic factors. RESULTS: Patients who were treated surgically had a better one-year survival rate (28.3%), than patients who received radiotherapy and/or chemotherapy (6.67%) or patients who refused any kind of treatment (3.45%), (p=0.006). Prolonged survival after surgical treatment was found in patients with single metastatic lesions and in patients with multiple metastatic lesions. CONCLUSIONS: Melanoma patients with single metastatic lesions to the brain seem to do better after surgical treatment. The role of surgical intervention in patients with multiple brain metastases needs re-evaluation from a big multicenter, prospective trial.