Keizo Yamamoto

Identification of the cis‐acting region in the NF2 gene promoter as a potential target for mutation and methylation‐dependent silencing in schwannoma

Although mutational inactivation and allelic loss in the NF2 gene appear to be causal events in the majority of vestibular schwannomas, involvement of another potentially important mechanism, transcriptional inactivation, has not been investigated.

Cloning and functional characterization of the 5'-flanking region of the human monocyte chemoattractant protein-1 receptor (CCR2) gene. Essential role of 5'-untranslated region in tissue-specific expression

The human monocyte chemoattractant protein-1 receptor designated hCCR2 is an essential co-receptor in cell entry by the human immunodeficiency virus as well as a receptor for monocyte chemoattractant protein-1, a member of the family of C-C chemokines that mediate monocyte chemotaxis. To elucidate the molecular mechanisms underlying the transcriptional regulation of hCCR2, we cloned and sequenced the hCCR2 gene; it was approximately 8 kilobase pairs in length and consisted of three exons divided by two introns. In the 5′-flanking region, there were the typical mammalian promoter consensus elements, a CAAT box and a TATA box, resulting in a single transcription initiation site. In addition, we found clustered tissue-specific cis-regulatory elements such as GATA consensus sequences, Oct-1 binding sequences, and CAAT/enhancer-binding protein binding sequences. Luciferase assays with various promoter deletions and gel mobility shift assays indicated that threecis-regulatory elements located within the region from −89 to +118 are required for basal activity in THP-1 cells. One element is an octamer sequence 36-base pair upstream from the TATA box; it binds mainly to Oct-1 and is capable of increasing transcriptional activity. The other two elements, which are tandem recognition sites of the CAAT/enhancer-binding protein family, are located in the 5′-untranslated region and account for the transcriptional activation as well as the tissue specificity of hCCR2.

Suprasellar hemangioblastoma in a patient with von Hippel-Lindau disease confirmed by germline mutation study: Case report and review of the literature

BACKGROUND Hemangioblastoma (HBL) in the suprasellar region is extremely rare. CASE DESCRIPTION A suprasellar mass was found in a 33-year-old woman with retinal HBL and bilateral adrenal pheochromocytomas. The diagnosis of von Hippel-Lindau (VHL) disease was confirmed preoperatively not only by these clinical manifestations but also by germline mutation study. The existence of VHL disease indicated a diagnosis of HBL for the suprasellar mass. The results of our mutation study indicated that this patient had type II VHL disease, suggesting that careful follow-up is essential for the early detection of renal cell carcinoma, which is often associated with type II VHL disease. Here, we summarize the previously reported features of sellar and suprasellar HBLs. CONCLUSIONS HBLs in this region may be one manifestation of VHL disease. Genetic testing of the VHL gene of our patient could provide useful information to determine appropriate medical care and management.

Randomized comparison of intra-arterial versus intravenous infusion of ACNU for newly diagnosed patients with glioblastoma

This prospective randomized trial was performed to compare the effectiveness of intra-arterial ACNU with intravenous ACNU in newly diagnosed patients with supratentorial glioblastoma. The primary end points were overall survival and progression-free survival. Within 3 weeks after surgery, patients were randomly assigned to receive either intravenous or intra-arterial ACNU (80 mg/m2) once every 6 weeks concomitant with radiotherapy. Intra-arterial ACNU was administered for the first 3 courses followed by intravenous administration. Eighty-four patients were enrolled onto this study and among them 82 patients who passed eligibility criteria were analyzed. Patients characteristics were not different significantly between 2 treatment arms. Median survival and progression-free survival time was 59 and 24 weeks, respectively for intra-arterial arm and 56 and 45 weeks, respectively for intravenous arm. There was no significant difference respectively between two treatment arms. Among the prognostic variables including age, Karnofsky performance status, extent of surgery and treatment arm, Coxs proportional hazards model showed that age was the only significant factor for both survival and progression-free survival (P=0.003 and 0.016, respectively). With regard to toxicity, there was no significant difference between two treatment arms. Leukoencephalopathy was not observed in intra-arterial arm. In conclusion, intra-arterial ACNU when administered by the method in this study does not increase the survival and progression-free survival of newly diagnosed patients with glioblastoma over that afforded by intravenous ACNU.

Expression of citrulline–nitric oxide cycle in lipopolysaccharide and cytokine-stimulated rat astroglioma C6 cells

Nitric oxide (NO) is involved in many physiological and pathological processes in the brain. NO is synthesized from arginine by nitric oxide synthase (NOS), with citrulline generated as a by-product of the reaction. Thus, citrulline can by recycled to arginine by argininosuccinate synthetase (AS) and argininosuccinate lyase (AL) via the citrulline-NO cycle. Rat astroglioma C6 cells were treated with bacterial lipopolysaccharide (LPS), interferon-gamma (IFNgamma) and tumor necrosis factor-alpha, and the expression of the enzymes of the citrulline-NO cycle was investigated by RNA blot and immunoblot analyses. NO production from arginine and citrulline was also assessed. iNOS mRNA and protein were induced 6-12 h after stimulation with LPS and cytokines and decreased at 24 h. AS mRNA increased up to 12 h and decreased at 24 h. AS protein increased gradually up to 48 h. On the other hand, AL mRNA remained unchanged by stimulation. NO production from arginine was enhanced by the treatment with LPS and cytokines. NO production was also observed when arginine was replaced by citrulline. These results indicate that NO production is enhanced in LPS- and cytokine-stimulated C6 cells due to induction of iNOS and that the citrulline-arginine recycling is important for NO production.

A Rare Case of Thyrotropin-Secreting Pituitary Adenoma Coexisting with Papillary Thyroid Carcinoma Presenting with Visual Disturbance without Hyperthyroidism

BACKGROUND Thyroid-stimulating hormone-secreting pituitary adenomas (TSHomas) are uncommon, and majority of the patients present with symptoms of hyperthyroidism. Herein, we report the first case of TSHoma with differentiated thyroid carcinoma (DTC) that presented with visual disturbance without any clinical feature of hyperthyroidism. CASE DESCRIPTION A 57-year-old man presented with left temporal hemianopsia of his left eye without any sign of hyperthyroidism. A mass lesion in the sellar and suprasellar region compressing the optic nerves was identified via magnetic resonance imaging. Free thyroxine and free triiodothyronine levels were slightly elevated, whereas the serum level of thyroid-stimulating hormone remained within normal range. Further endocrinologic examination led to the preoperative diagnosis of TSHoma. Ultrasonography and 111In-octreotide scan showed a mass lesion in left lobe of the thyroid gland, and subsequent thyroid aspiration biopsy confirmed the diagnosis of papillary thyroid carcinoma. After administration of short-acting octreotide to prevent thyrotoxic crisis in the perioperative period, the tumor was removed via endoscopic transnasal-transsphenoidal surgery, and the pathologic diagnosis of TSHoma was made. His visual acuity improved, and free triiodothyronine and free thyroxine levels normalized. He underwent thyroidectomy 3 months later after endoscopic transnasal-transsphenoidal surgery. CONCLUSIONS Herein, we report the first case of TSHoma with DTC that presented with visual disturbance without any clinical feature of hyperthyroidism and reviewed the 13 reported cases of TSHoma coexisting with DTC. The optimal treatment strategy in patients with TSHoma and coexistent DTC has not been established, and individualized therapeutic strategies are needed.