Effects of Endogenous and Exogenous Prostaglandin E2on the Proliferation and Differentiation of a Mouse Cementoblast Cell Line (OCCM-30)

BACKGROUND

Cementum formation is considered to be a critical event for successful regeneration of periodontal tissues. Cementoblasts share many characteristics with osteoblasts. Prostaglandin E(2) (PGE(2)) is an important local factor in bone metabolism. Although the effects of PGE(2) on osteoblasts are well known, its effects on cementoblasts have not yet been established. We examined the effects of PGE(2) on proliferation and differentiation in a mouse cementoblast cell line, OCCM-30 cells.

METHODS

OCCM-30 cells were treated with three concentrations of PGE(2) (10, 100, and 1,000 ng/ml). Cell number, alkaline phosphatase (ALP) activity, and expression for mineralization-related genes were determined. Osteoprotegerin (OPG) and receptor activator of nuclear factor-kappa B (NF-kappaB) ligand (RANKL) expression were also examined by real-time polymerase chain reaction (RT-PCR) and enzyme-linked immunosorbent assay (ELISA).

RESULTS

The addition of PGE(2) at the highest dose used in this study suppressed cell proliferation of OCCM-30 cells. The expression of mineralization-related marker mRNA, such as type 1 collagen, ALP, bone sialoprotein (BSP), and osteocalcin (OCN), was constitutively detected in OCCM-30 cells. PGE(2) dose dependently stimulated ALP activity and BSP-mRNA expression in OCCM-30 cells at day 3. Transcripts for OPG and RANKL and the protein level of OPG in culture media were upregulated with PGE(2) stimulation.

CONCLUSION

These results demonstrate that PGE(2) suppressed cementoblast proliferation but stimulated ALP activity and the BSP-mRNA level, suggesting a role of PGE(2) in controlling cementoblast differentiation, and further indicate that PGE(2) modulates RANKL and OPG expression in cementoblasts; the increase of OPG secreted from cementoblasts with PGE(2) stimulation may be essential to protect the root surface from resorption.

[Investigation of microwave coagulo-necrotic therapy for 21 patients with small hepatocellular carcinoma less than 5 cm in diameter]

Microwave coagulo-necrotic therapy (MCN) was performed in 21 patients with small hepatocellular carcinoma less than 5cm in diameter and this therapeutic method was determined to be effective from the following results. 1) A marked low density area was seen in the region receiving the therapy and no enhanced findings were observed by enhanced CT one month postoperatively. 2) Recurrence appeared in 5 patients (23.8%) and only one patient died 1 year and 6 months after the operation. However, the other 20 patients survived for a maximum of 3 years and 2 months postoperatively. 3) The levels of total bilirubin and GOT in these patients were similar to those of patients who underwent hepatectomy. However, the levels of prothrombin time and hepaplatin test in patients with MCN changed less than in those who received hepatectomy. 4) Tendency of the renal failure was seen in 2 patients, and the other 19 patients did not have any complication postoperatively.

A new technique of hepatectomy using an occlusion balloon catheter for the hepatic vein

To minimize intraoperative bleeding and allow more accurate resection, we have devised a new technique for hepatectomy. In addition to occlusion of the afferent vessels, we occlude the hepatic vein at the hepatocaval junction using a balloon catheter inserted transhepatically under intraoperative ultrasonic guidance. We have performed eight hepatectomies using this method. A sequence of 15 minutes of vascular occlusion followed by 5 minutes reperfusion was repeated throughout the operation, and the total ischemic time ranged from 45 to 90 minutes. This method greatly decreased intraoperative bleeding without causing significant elevation of the postoperative transaminase or lactic dehydrogenase levels when compared with occlusion of only the afferent vessels or nonischemic resection using a microwave tissue coagulator in patients undergoing equivalent resections. Also, the postoperative prothrombin time recovered to a significantly higher level, and there were no fatal postoperative complications using this method. Our method is useful for systematic hepatic resection along the hepatic vein or for resection of tumor sited at the confluence of the hepatic vein.

[Useful CT findings in a case of idiopathic perforation of the descending colon]

Idiopathic perforation of the descending colon is an uncommon disease. The disease has tendency to complicate with severe pan-peritonitis at relatively early stage. So early diagnosis and treatment is required. We encountered a 83-years-old female patient with idiopathic perforation of the descending colon. CT revealed the findings suggestive of free air in the retro-peritoneal space. We thought CT may be useful diagnostic approach to make correct diagnosis of the perforation of the colon.