Terminal deoxynucleotidyltransferase forms a ternary complex with a novel chromatin remodeling protein with 82 kDa and core histone

BACKGROUND: Terminal deoxynucleotidyltransferase (TdT) is a DNA polymerase that enhances the Ig and TcR gene diversity in the N region at the junctions of variable (V), diversity (D) and joining (J) segments in B- and T-cells. TdT synthesizes the N region in concert with many proteins including DNA-PKcs, Ku70 and Ku86. To elucidate the molecular mechanism of the N region synthesis, we first attempted to isolate the genes with products that directly interact with TdT. RESULTS: Using a yeast two-hybrid system, we isolated a cDNA clone encoding a novel nuclear protein that interacts with TdT. This protein was designated as TdT interacting factor 2 (TdIF2). The confined region of the C-terminal in TdIF2 is involved in specific interaction with the entire C-terminal in TdT. TdIF2 contains an acidic region comprised of 42 residues. TdIF2 was shown to bind specifically to a core histone by pull down assay using specific antibodies against TdIF2. When a TdT/TdIF2 complex was applied on to a DNA-cellulose column, only TdT bound to the column while TdIF2 passed through. TdIF2 reduces the TdT activity to 46% of its maximum value in vitro assay system using activated DNA as primer. CONCLUSIONS: TdIF2 binds directly to TdT and core histone. Furthermore, TdT, TdIF2 and core histone form a ternary complex. TdIF2 liberates H2A/H2B from a core histone in correlation with PCNA. The enzymatic consequence of the TdIF2/TdT complex is the reduction of TdT activity in vitro. TdIF2 would function as a chromatin remodeling protein at the N region synthesis.     

Infantile hemangioendothelioma of the thymus with massive pleural effusion and Kasabach-Merritt syndrome: Histopathological, flow cytometrical analysis of the tumor

Infantile hemangioendothelioma of the thymus is a rare disease. We describe a patient who developed a large anterior mediastinal mass, severe thrombocytopenia and massive pleural effusion at 1 month of age. Glucocorticosteroid and irradiation therapy had no effect on either the tumor size or clinical symptoms and the tumor was resected subtotally. Three months after the subtotal resection, the remaining tumor had almost disappeared and the symptoms had resolved. The patient has now been well for 1 year after surgery without evidence of recurrence. The tumor tissue was characterized by prominent vascular endothelial proliferation intermixed with a normal thymic structure, producing a picture consistent with that of an infantile hemangioendothelioma in the thymus, lmmunohistochemically, the tumor cells showed positive staining for vimentin, factor VIII and CD34. The DNA stemline and proliferative activity were examined by flow cytometry, which revealed a diploid stemline with a low growth fraction. DNA content and cell cycle analyses of the tumor tissue may be useful for predicting the biological behavior of the tumor.     

Investigation of blood flow in meningothelial and fibrous meningiomas by xenon-enhanced CT scanning

Abstract

We investigated whether xenon-enhanced computed tomography was able to separate meningothelial meningioma from fibrous meningioma. Cerebral blood flow was studied by xenon-enhanced computed tomography in six patients with incidentally detected intracranial meningiomas. All of the tumors were small (<32mm) and there was little or no péritumoral edema. Three patients had meningothelial meningioma and three patients had fibrous meningioma. The tumor blood flow and the contralateral tissue blood flow were determined. The ratio of these parameters was 7.753 ± 0.467 for meningothelial meningiomas and 0.809±0.105 for fibrous meningiomas, with a significant difference between the two tumor subtypes (p = 0.0185). There was no correlation between the signal intensity on magnetic resonance imaging and tumor subtype, and the findings on cerebral angiography also did not indicate the subtype. In conclusion, xenon-enhanced computed tomography showed a difference between smaller meningothelial and fibrous meningiomas in patients with normal surrounding brain tissue. We could not confirm that xenon-enhanced computed tomography was able to distinguish the subtype of meningioma because of the small number of subjects in this study, but our findings might expand interest in the clinical use of this method. [Neurol Res 2000; 22: 615-619]     

Case Report: Determination of Primary Foci of Metastatic Tumors by p53 Mutational Analysis in Intraesophageal Multiple Carcinomas

It is well known that squamous carcinomasfrequently develop multifocally, either synchronously ormetachronously, in the upper aerodigestive tract (1).Such phenomena were first reported by Slaughter et al in 1953, and they were named fieldcancerization (2). Using recent molecular biologytechniques, these multiple carcinomas have been revealedto arise from independent origins (3). Esophagealcarcinomas have been reported to frequently metastasize tothe lymph nodes even at the early stage of tumorextension (4). Furthermore, simultaneous multifocalcancer development is not rare in the esophagus (5). In cases of intraesophageal multiple carcinomaswith lymph node metastases, the primary focus of themetastatic tumors cannot be identified by conventionalhistologic examination. Here we report a case of intraesophageal multiple carcinomas in whichthe attributed foci of lymph nodal metastases could beclearly identified by analyzing the p53 gene mutationalstatus used as a clonal marker.     

Improvement of the Tissue-adhesive and Sealing Effect of Fibrin Sealant Using Polyglycolic Acid Felt

Although fibrin sealant (FS) has an advantage of high biocompatibility, its adhesive force and sealing effect have been generally considered to be inadequate. In the present study, a high adhesive force and sealing effect were obtained by first rubbing fibrinogen solution into the target tissue, attaching polyglycolic acid (PGA) felt to the treated area, and finally spraying it with FS. This method was compared with three conventional FS application methods and a method using fibrin glue-coated collagen fleece. The adhesive force resulting from the present method was 12 times higher than that for the sequential application method, 4.5 times higher than the spray method, 2.5 times higher than the rubbing and spray method, and 2.2 times higher than the use of fibrin glue-coated collagen fleece. The high adhesive force of FS with PGA felt seemed to be due the high fibrin content of the fibrin gel (FG). Light and electron microscopic observations suggested that the formation of FG in closer contact with the muscle fibers was a factor contributing to this superior adhesive force. Comparison of the sealing effect of the present method with other methods using various biomaterials in combination with FS showed that the sealing effect of FS with PGA felt was 1.4 times higher that of polyglactin 910, 1.8 times that of polytetrafluoroethylene, and 6.7 times that of oxidized regenerated cellulose.     

Antibody‐mediated rejection after ABO‐incompatible pediatric living donor liver transplantation for propionic acidemia: A case report

We herein present the case of a four‐yr‐old boy with PA who developed AMR after ABO‐incompatible LDLT despite undergoing B cell desensitization using rituximab. Although the CD19+ lymphocyte count decreased to 0.1% nine days after the administration of rituximab, he developed a high fever which was accompanied by arthralgia due to a streptococcal infection 13 days after rituximab prophylaxis. After the clearance of the infection, he underwent ABO‐incompatible LDLT 36 days after the administration of rituximab. The CD19+ lymphocyte count just prior to LDLT was 1.2%. He developed AMR five days after LDLT, and the antidonor‐type IgM and IgG antibody titers increased to 1:1024 and 1:1024, respectively. He was treated by plasma exchange, IVIG, steroid pulse therapy, and rituximab re‐administration; however, his liver dysfunction continued. Despite intensive treatment, he died due to complicated abdominal hernia, acute renal failure, and ARDS. This case suggests that a streptococcal infection may induce the activation of innate immune responses; thus, additional desensitization therapy should be considered prior to ABO‐incompatible LDLT if B cell reactivation is suspected.     

Prenatal diagnosis of Gaucher disease using next‐generation sequencing

In the prenatal diagnosis of Gaucher disease (GD), glucocerebrosidase (GBA) activity is measured with fetal cells, and gene analysis is performed when pathogenic mutations in GBA are identified in advance. Herein is described prenatal diagnosis in a family in which two children had GD. Although prior genetic information for this GD family was not obtained, next‐generation sequencing (NGS) was carried out for this family because immediate prenatal diagnosis was necessary. Three mutations were identified in this GD family. The father had one mutation in intron 3 (IVS2 + 1), the mother had two mutations in exons 3 (I[‐20]V) and 5 (M85T), and child 1 had all three of these mutations; child 3 had none of these mutations. On NGS the present fetus (child 3) was not a carrier of GD‐related mutations. NGS may facilitate early detection and treatment before disease onset.