Hirotaka Sakaki

Regulation of synthesis of osteoprotegerin and soluble receptor activator of nuclear factor-κB ligand in normal human osteoblasts via the p38 mitogen-activated protein kinase pathway by the application of cyclic tensile strain

Mechanical stress is thought to play an important role in bone remodeling. However, the correlation between mechanical stress and bone remodeling is poorly understood. In this context, using a model of cyclic tensile strain (CTS) toward human osteoblasts, synthesis of osteoprotegerin (OPG) and soluble receptor activator of nuclear factor-κB ligand (sRANKL), and the activation of mitogen-activated protein kinases (MAPKs) were examined. The application of 7%, 0.25-Hz CTS once a day for 4 h for 3 successive days simultaneously caused an increase of OPG synthesis and a decrease of sRANKL release and RANKL mRNA expression in osteoblasts. As for MAPKs activation in osteoblasts with the application of CTS, p38 MAPK was activated 10–20 min after the application of CTS, but extracellular signal-regulated kinase (ERK1/2) and c-Jun NH2-terminal kinase (JNK) were not activated by such application. Furthermore, when CTS was applied once a day for 4 h for 1, 2, or 3 successive days to osteoblasts, p38 MAPK activation was maintained during the 3-day period but ERK1/2 activation was downregulated from day to day, simultaneously. Then, when CTS was applied once a day for 4 h for 3 successive days to osteoblasts pretreated with the p38 MAPK inhibitor SB203580 for 1 h, OPG synthesis was dose-dependently suppressed and inhibition of sRANKL release and RANKL mRNA expression was abrogated. These results indicate that biological responses of OPG and sRANKL synthesis in osteoblasts to the application of CTS are regulated via the p38 MAPK pathway and suggest that CTS might modulate and regulate bone metabolism.

Platelet-activating factor enhances the expression of vascular endothelial growth factor in normal human astrocytes

Vascular endothelial growth factor (VEGF) is a potent and specific mitogen for vascular endothelial cells. To examine whether platelet-activating factor (PAF) induces the expression of VEGF in human astrocytes, we stimulated cultured normal astrocytes with PAF and performed semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR) or real-time quantitative PCR for VEGF mRNA and enzyme-linked immunosorbent assay for VEGF protein. PAF increased the expression of VEGF in astrocytes in time- and dose-dependent manners. After 24-h stimulation, 10 nM PAF increased the levels of VEGF protein in astrocyte-conditioned medium by 1.3-fold. When the cells were subjected to hypoxia, the PAF-induced production of VEGF was enhanced by 6.7-fold as compared to the unstimulated cells incubated under normoxia. Dexamethasone was found to inhibit the enhanced VEGF production in response to the stimulation with PAF under hypoxia. We conclude that PAF induces VEGF gene expression in human astrocytes, and the PAF-induced increase in the expression of VEGF may modulate nervous tissue injury due to hypoxia.

Production of growth related oncogene protein-α in human umbilical vein endothelial cells stimulated with soluble interleukin-6 receptor-α: role of signal transducers, janus kinase 2 and mitogen-activated kinase kinase

Growth-related oncogene protein-alpha (GRO-alpha) is a member of the C-X-C chemokine family with a wide variety of biological activities. We studied the production of GRO-alpha by human umbilical vein endothelial cells (HUVEC) in response to the stimulation with soluble form of interleukin-6 receptor alpha (sIL-6R). sIL-6R stimulated HUVEC to express GRO-alpha mRNA and secrete GRO-alpha protein in concentration-and time-dependent manners. The sIL-6R-induced GRO-alpha expression was inhibited by the pretreatment of the cells with AG490, a janus kinase 2 (JAK2) inhibitor, or with U0126, a MAP kinase-ERK kinase (MEK) inhibitor. sIL-6R also induced the phosphorylation of both Src homology 2-protein tyrosine phosphatase-2 (SHP-2), signal transducer and activator of transcription 3 (STAT3) and MEK. AG490 pretreatment inhibited the MEK phosphorylation but did not affect the STAT3 phosphorylation. We conclude that sIL-6R induces GRO-alpha expression in HUVEC through the activation of JAK2 and MEK.

Interleukin-1β enhances the angiotensin-induced expression of plasminogen activator inhibitor-1 through angiotensin receptor upregulation in human astrocytes

Plasminogen activator inhibitor-1 (PAI-1) regulates not only fibrinolysis but extracellular matrix remodeling, and angiotensin II is known to play an important role in controlling the expression of PAI-1 in astrocytes. We have studied the effect of interleukin-1beta (IL-1beta), one of major cytokines also active in the nervous system, on the angiotensin II-induced expression of PAI-1 in human astrocytes. Cultures of normal human astrocytes were stimulated with IL-1beta and angiotensin II, and the expression of mRNAs for angiotensin II type 1 receptor (AT1) and PAI-1 was analyzed by reverse transcription-polymerase chain reaction (RT-PCR) or real-time quantitative PCR. PAI-1 protein in astrocyte-conditioned medium was measured by enzyme-linked immunosorbent assay (ELISA). IL-1beta enhanced the expression of AT1 in astrocytes in time- and concentration-dependent manners. After 24-h stimulation, 10 ng/ml IL-1beta and 10 nM angiotensin II increased the levels of PAI-1 protein in astrocyte-conditioned medium by 1.9-fold and 1.8-fold of the basal value, respectively. There was no synergistic effect when the cells were stimulated simultaneously with IL-1beta and angiotensin II. When the cells were stimulated, with angiotensin II, 16 h after the stimulation with IL-1beta, the production of PAI-1 was enhanced by 1.4-fold as compared to the cells stimulated only with IL-1beta. CV-11794, an AT1 antagonist, inhibited the enhanced PAI-1 production in response to angiotensin II. We conclude that IL-1beta increases angiotensin II-induced PAI-1 secretion by astrocytes through the induction of AT1, and the enhanced secretion of PAI-1 may modulate functions of plasminogen activators in the nervous system.

Interleukin-1 induces the expression of vascular endothelial growth factor in human pericardial mesothelial cells

Vascular endothelial growth factor (VEGF) is a mitogen for endothelial cells. We have studied the production of VEGF by human pericardial mesothelial cells. Mesothelial cells were separated by scraping the pericardial surface during cardiac surgery and cultured. When stimulated with interleukin (IL)-1α, pericardial mesothelial cells expressed VEGF mRNA and protein in concentration- and time-dependent manners. Hypoxia was also found to enhance mesothelial VEGF mRNA expression. The cells expressed mRNA for Flt-1 (VEGF receptor 1) and Flk-1 (VEGF receptor 2), and exogenous VEGF was found to have migration-promoting activity on cultured cells. We conclude that pericardial mesothelial cells express VEGF, which may serve as an autocrine growth-regulatory mechanism.

Professional oral health care reduces oral mucositis pain in patients treated by superselective intra-arterial chemotherapy concurrent with radiotherapy for oral cancer

PurposeOral mucositis (OM) is a painful complication of radiation therapy (RT) for head and neck cancer. OM can compromise nutrition, require opioid analgesics and hospitalization for pain control, and lead to interruption of treatment. Severe oral mucositis appears inevitable in superselective intra-arterial chemotherapy concurrent with radiotherapy (SSIACRT), requiring management of OM for the patient. The objective of this study was to assess the utility of professional oral health care (POHC) for the management of OM in patients undergoing SSIACRT.MethodsThirty-three patients were enrolled in this study. The first 17 patients underwent SSIACRT before we created an oral management team, and thus did not receive POHC. The remaining 16 patients received POHC. Fever duration, duration of oral feeding difficulty, opioid usage, duration of opioid administration, duration of hospitalization, and number of hospital days from the end of irradiation to discharge were compared between these two groups.ResultsMedian total dose of morphine during SSIACRT, median number of hospital days from end of irradiation to discharge, and duration of hospitalization all differed significantly between groups (P < 0.05). Duration of opioid administration, fever duration, and duration of oral feeding difficulty did not differ significantly between groups.ConclusionsThese findings indicate that POHC may reduce opioid use and shorten the hospital stay. Such results might be obtained through infection control by POHC. This report appears to be the first study to evaluate the efficiency of POHC in SSIACRT for oral cancer from the perspective of mucositis pain and opioid use.

Expression of interferon‐stimulated gene 20 in vascular endothelial cells

ISG20 is an ribonuclease specific for single‐stranded RNA and considered to play a role in innate immunity against virus infections. We herein show that both poly IC, an authentic double‐stranded RNA, and IFN‐γ induced ISG20 expression in cultured HUVEC. Poly IC‐induced ISG20 expression was inhibited by LY294002, an inhibitor of PI3K, or by RNA interference against IFN regulatory factor three. ISG20 expression was not induced by IFN‐β, loxoribine or CpG oligonucleotide. These results suggest that ISG20 induction by poly IC may not be dependent on the IRF‐3‐mediated type I IFN induction pathway in HUVEC. ISG20 may be involved in innate immunity against viral infection in vascular endothelial cells.

Huge Gingival Cyst of the Adult: a Case Report and Review of the Literature

Abstract Gingival cysts of adults are uncommon gingival lesions that are usually found within attached or unattached soft tissues. They are commonly seen in the canine and premolar regions of the mandible, and are sometimes confused with lateral periodontal cysts. Gingival cyst lesions in adults may appear bluish due to fluid and cause pressure resorption of the labial bone. Gingival swelling and the faint shadow of radiolucency are a characteristic of the gingival cysts of adults. We report here the case of a large gingival cyst in an adult, which was unlike most other reported cases that have cyst sizes of less than 0.6 cm. The incidence of gingival cysts of adults shows a racial predilection, with Asians revealing a much lower prevalence of the lesion than Caucasians; however, there is no gender difference in the incidence of the disease. The case was treated with simple surgical excision and has shown no tendency for recurrence.

Pleomorphic Adenoma of the Palate Detected by Positron Emission Tomography/Computed Tomography Screening

Abstract We report a case of pleomorphic adenoma on the left side of the hard palate detected by positron emission tomography/computed tomography. A 52-year-old woman underwent whole-body positron emission tomography examination with fluorodeoxyglucose for cancer screening at a nearby medical centre, which showed fluorodeoxyglucose uptake in the hard palate. The patient was referred to the Department of Dentistry and Oral Surgery, Hirosaki University School of Medicine, Hirosaki, Japan, for further evaluation. The lesion was 10 × 8 mm in size, with a clearly demarcated border, and the elastic soft mass had intact mucosa covering its surface. Preoperative magnetic resonance imaging showed a mass in the left side of the hard palate corresponding to the area on positron emission tomography/computed tomography. The clinical diagnosis was benign tumour of the palate. Surgical resection was performed under general anaesthesia. The histopathological diagnosis was pleomorphic adenoma. There have been no signs of recurrence 1 year after surgery.