Effect of promoter methylation of the p16 gene on phosphorylation of retinoblastoma gene product and growth of hepatocellular carcinoma cells.

The biological significance of hypermethylation of p16 gene promoter in human hepatocellular carcinoma (HCC) cells remains to resolved. In order to clarify the significance of methylation of p16 gene promoter, we examined the methylation status of p16 gene in association with phosphorylation of retinoblastoma gene product (pRb) and cell growth in human HCC cell lines. The presence of methylation was examined by methylation-specific PCR. Expression and phosphorylation of p16 and pRb were examined by Western blot analysis. Genetic changes were analyzed by multiplex PCR and DNA sequencing. The effect of demethylation of p16 was assessed by cell growth. p16 gene promoter was methylated in HuH7 and HLF cells. The demethylating agent, 5-aza-2-deoxycytidine (5-Aza-CdR), upregulated p16 mRNA in HuH6 and HuH7 cells. 5-Aza-CdR increased p16 protein expression in HuH6, HuH7, and HLF cells, and it clearly decreased the phosphorylation level of pRb in HuH6, HuH7 and PLC/PRF/5 cells. Treatment with 5-Aza-CdR inhibited the growth of HuH7 cells. Homozygous deletion and significant mutations were absent. Methylation in the p16 promoter region is biologically significant, being associated with phosphorylation of pRb and cell growth in human HCC cells.     

Property of thimerosal-induced decrease in cellular content of glutathione in rat thymocytes: a flow cytometric study with 5-chloromethylfluorescein diacetate.

There is a concern on the part of public health community that adverse health consequences by thimerosal, a preservative in vaccines for infants, may occur among infants during immunization schedule. Therefore, the effect of thimerosal on cellular content of glutathione was examined on thymocytes obtained from 4-week-old rats using a flow cytometer and 5-chloromethylfluorescein diacetate. Thimerosal at concentrations ranging from 1 to 10 microM reduced the cellular content of glutathione in a concentration-dependent manner, and the complete depletion of cellular glutathione was observed when the cells were treated with 30 microM thimerosal. L-Cysteine significantly attenuated the actions of thimerosal to reduce the glutathione content and to increase the intracellular Ca2+ concentration. Prolonged incubation (24 h) with 1-3 microM thimerosal induced the apoptosis. The cytotoxic action of thimerosal was greatly augmented when the cells suffered oxidative stress induced by H2O2. It may be unlikely that thimerosal exerts potent cytotoxic action under the in vivo condition because the blood concentration of thimerosal after receiving vaccines does not seem to reach micromolar range and nonprotein thiols at micromolar concentrations are present in the blood.     

Early stage clear cell adenocarcinoma of the colon examined in detail with image-enhanced endoscopy: a case report

Primary clear cell adenocarcinoma (CCA) of the colorectum is a rare tumor. We report on a 48-year-old man with early stage CCA in the descending colon who underwent detailed examination with image-enhanced endoscopy, such as magnifying endoscopy with narrow-band imaging and crystal violet staining. The tumor was treated successfully with endoscopic mucosal resection at our hospital.     

Effects of vasopressin during a pulmonary hypertensive crisis induced by acute hypoxia in a rat model of pulmonary hypertension

Background

A pulmonary hypertensive crisis (PHC) can be a life-threatening condition. We established a PHC model by exposing rats with monocrotaline (MCT)-induced pulmonary hypertension to acute hypoxia, and investigated the effects of vasopressin, phenylephrine, and norepinephrine on the PHC.

Spirotoamides A and B, novel 6,6-spiroacetal polyketides isolated from a microbial metabolite fraction library

Two new 6,6-spiroacetal polyketides, spirotoamides A (1) and B (2), were isolated from a microbial metabolite fraction library of Streptomyces griseochromogenes JC82-1223 by screening of structurally unique compounds based on a search of spectral database. The fraction library was constructed using a systematic separation method to efficiently discover new metabolites from microbial sources such as actinomycetes and fungi. The structures of 1 and 2 were elucidated by 2D-NMR and mass spectrometric measurements. They belong to a class of polyketides, and contain a 6,6-spiroacetal core structure and a carboxamide group. The biosynthetic pathway of 1 and 2 is discussed in the text.     

OSTEOSARCOMA AS A SECOND MALIGNANCY AFTER TREATMENT FOR NEUROBLASTOMA

A 4-month old girl was diagnosed as having stage IV neuroblastoma of the right adrenal gland. Preoperative chemotherapy was given, followed by local surgical excision. Postoperatively, irradiation of the tumor bed and adjuvant chemotherapy was given for 11 months. Nine years after cessation of chemotherapy, the patient developed left hip-joint pain. Biopsy of the ischium showed chondroblastic osteosarcoma. Limb salvage surgery was performed after preoperative chemotherapy. Postoperatively, adjuvant chemotherapy was given for 14 months. Twenty-two months after treatment for the secondary osteosarcoma, the patient has been remained in disease-free condition without any evidence of relapse. A second osteosarcoma occurring outside the radiation field after treatment for neuroblastoma is quite rare. This unusual case emphasized the need for close monitoring for development of second malignant neoplasms in survivors of neuroblastoma even in the absence of a known predisposing factor, such as radiation therapy.