Action of xyloglucan hydrolase within the native cell wall architecture and its effect on cell wall extensibility in azuki bean epicotyls

Xyloglucan hydrolase (XGH) has recently been purified from the cell wall of azuki bean (Vigna angularis Ohwi et Ohashi) epicotyls as a new type of xyloglucan-degrading enzyme [Tabuchi et al. (2001) Plant Cell Physiol. 42: 154]. In the present study, the effects of XGH on the mechanical properties of the cell wall and on the level and the molecular size of xyloglucans within the native wall architecture were examined in azuki bean epicotyls. When the epidermal tissue strips from the growing regions of azuki bean epicotyls were incubated with XGH, the mechanical extensibility of the cell wall dramatically increased. XGH exogenously applied to cell wall materials (homogenates) or epidermal tissue strips decreased the amount of xyloglucans via the solubilization of the polysaccharides. Also, XGH substantially decreased the molecular mass of xyloglucans in both materials. These results indicate that XGH is capable of hydrolyzing xyloglucans within the native cell wall architecture and thereby increasing the cell wall extensibility in azuki bean epicotyls.

Expression of inflammatory cytokines and beta-defensin 1 mRNAs in porcine epithelial rests of Malassez in vitro

In the present study, we investigated the mRNA expression of inflammatory cytokines, including interleukin (IL)-1 alpha, IL-6, IL-8, and granulocyte macrophage colony-stimulating factor (GM-CSF), and beta defensin 1 (BD-1), an antimicrobial peptide, in the epithelial rests of Malassez in vitro. A reverse transcription-polymerase chain reaction (RT-PCR) assay was performed in order to observe the expression of these mRNAs. The effect of lipopolysaccharide (LPS) on the mRNA expression was also studied by quantitative RT-PCR assay, with a LightCycler, using the double-stranded DNA dye SYBR Green I. The mRNAs of the four kinds of inflammatory cytokines and BD-1 were detected in the epithelial cells under normal culture conditions. Immunocytochemical staining showed the expression of CD14, a receptor for LPS, on the epithelial cells. The mRNA expressions of IL-1 alpha, IL-6, IL-8, and GM-CSF were upregulated by stimulation with LPS, in a dose- and time-dependent manner. Epithelial cells incubated with 1000 ng/ml of LPS for 6 h showed the most significant upregulation of the cytokine mRNAs. On the other hand, no obvious alteration of BD-1 expression by LPS stimulation was observed. The results indicated that the epithelial rests of Malassez may actively participate in the inflammatory response to bacterial infection, and that they play an important role in the defense mechanism of the radicular cyst.

Immunohistochemical localization of amelogenin in human odontogenic tumors, using a polyclonal antibody against bovine amelogenin

In the present study, we investigated the localization of amelogenin in odontogenic tumors, using an anti-amelogenin polyclonal antibody. In order to make the antibody, antisera against an amelogenin fraction obtained from the enamel matrix of unerupted bovine tooth was raised in rabbits. By Western blot analysis, a main band of 25 kDa and six minor bands (6.8, 12, 18, 20, 23, and 27 kDa) were detected under nonreducing conditions. Immunoreactivity for the amelogenin was observed in ameloblasts and in the immature enamel matrix of 4-day-old rats. In odontogenic tumors, positive reactions for amelogenin were localized in limited areas in adenomatoid odontogenic tumor, calcifying odontogenic cyst, primary intraosseous carcinoma and odontoma. The strongest immunoreactions were shown in enamel matrices in odontomas. Small mineralized foci in epithelial nests showed positive reactions, and a few reactions were observed in epithelium adjacent to the mineralized foci. In calcifying odontogenic cysts, some ghost cells in the lining epithelium were strongly stained. The results indicate that the present antibody for amelogenin is useful for the determination of odontogenic tumors, especially in those in which small mineralized foci are present in the epithelial nests.

Conservative therapy for adenocarcinoma and atypical endometrial hyperplasia of the endometrium in young women: central pathologic review and treatment outcome

Thirty-nine patients with endometrioid adenocarcinoma (EA) and atypical hyperplasia (AH) of the endometrium who received conservative treatment to preserve fertility were collected from member institutions of the Japan Gynecologic Oncology Study Group. Twenty-nine and ten were originally diagnosed with EA without myometrial invasion and AH, respectively. We performed a central pathological review to make definite diagnoses, and the diagnosis of EA in 29 cases was changed to AH in ten, complex hyperplasia in three and atypical polypoid adenomyoma in three, and AH in ten was changed to EA in one and simple hyperplasia in one. Nine of 12 women (75%) with EA and 15 of 18 women (83%) with AH had an initial response to medroxyprogesterone acetate (MPA) treatment. Two of nine responders with EA later developed relapse, and one of them had metastasis to the left obturator lymph node. Two became pregnant, and one delivered one full-term infant. One of the responders with AH had a relapse in the endometrium. Five became pregnant, and four delivered four normal infants. The young women with endometrial carcinoma localized in the endometrium who wish to preserve fertility may be treated as successfully with MPA as those with AH.

Sodium nitroprusside-induced seizure and taurine release from rat hippocampus

We have recently reported that the nitric oxide (NO) donor, sodium nitroprusside (SNP), induces seizures which are associated with an increase in the basal release of aspartate and glutamate from rat hippocampus (Kaku et al., 1998). In order to determine whether taurine release occurs with SNP-induced seizures, we examined the effects of NO-related compounds, i.e., the NO trapper, diethyldithiocarbamate (DETC), the superoxide radical scavenger, dithiothreitol (DTT), the xanthine oxidase inhibitor, oxypurinol and the guanylyl cyclase inhibitor, 1H-(1,2,4)oxadiazole(4,3-a)quinoxalin-1-one (ODQ), on SNP-induced seizures and in vivo taurine release from rat hippocampus using microdialysis. Perfusion with 0.5mM SNP provoked seizures and significantly increased taurine release, with the increase in release occurring primarily during reperfusion with artificial cerebrospinal fluid lacking SNP. Perfusion with 5mM DETC significantly abolished the SNP-induced seizures and reduced taurine release during and after perfusion with the drugs. Perfusion with 1mM DTT significantly reduced both the frequency of the SNP-induced seizures and taurine release during and after perfusion with the drugs. Perfusion with 1 mM oxypurinol or 0.5 mM ODQ did not reduce the frequency of the SNP-induced seizures, but tended to decrease taurine release during and after perfusion with the drugs. These results demonstrate that SNP-induced seizures are triggered by an increase in both NO and peroxynitrite and are related to an increase in taurine release from rat hippocampus.

Immunohistochemical localization of large chondroitin sulphate proteoglycan in porcine gingival epithelia

In this study, we report the immunohistochemical localization of versican in healthy porcine gingival epithelia. The monoclonal antibody (mAb), 5D5, specifically recognizes core proteins of large chondroitin sulphate proteoglycans such as versican, neurocan and brevican, but not the core protein of aggrecan. Because neurocan and brevican appear to be specific to nervous tissue, the large chondroitin sulphate proteoglycans examined in this study is most likely versican. In the keratinized layer of the attached gingival epithelium, the basal and spinous cell surfaces showed intense staining for mAb 5D5. In the parakeratinized layer of the sulcus epithelium, the localization was restricted to the basal and lower spinous layers. In the junctional epithelium, intense staining was observed in one or two cell layers near the enamel surface. Immunoelectron microscopy revealed high-density depositions of 5D5 immunoreactivity on epithelial cell surfaces. At the enamel surface, 5D5 immunoreactivity was localized to the dental cuticle of the junctional epithelium but was not present in the internal basal lamina. These results suggest that versican, a large chondroitin sulphate proteoglycan, is involved in epithelial differentiation and downgrowth.

Differential expression of human beta-defensin 2 in keratinized and non-keratinized oral epithelial lesions; immunohistochemistry and in situ hybridization

Human beta-defensin(hBD)-2, an antimicrobial peptide, is produced by various epithelial cells. Because hBD-2 expression in the oral epithelium has not been assessed, we investigated its localization in normal oral epithelium and epithelial lesions. hBD-2 expression was studied using immunohistochemistry and in situ hybridization on formalin-fixed, paraffin-embedded tissue sections from 30 cases of squamous cell carcinoma and 6 cases of leukoplakia. Immunostaining for hBD-2 was more intense in hyperkeratinized than in ortho- or non-keratinized epithelium. In contrast, signals for hBD-2 mRNA were frequently stronger in non-keratinized epithelium than in hyper- or ortho-keratinized epithelium. The results suggest that keratinization in oral epithelium plays an important role in the biological function of hBD-2 both at the mRNA level and in the retention of the peptide in the epithelium.

Sodium nitroprusside-induced seizures and adenosine release in rat hippocampus

In the present study, we examined the effects of nitric oxide (NO)-related compounds, i.e. sodium nitroprusside (NO donor), diethyldithiocarbamate (NO trapper) and dithiothreitol (superoxide radical scavenger) on release of aspartate and adenosine from rat hippocampus using electrophysiological and microdialysis methods. Perfusion with 0.05 or 0.5 mM sodium nitroprusside significantly reduced high K(+)-evoked release of aspartate during high K(+) perfusion. Perfusion with 0.5 mM sodium nitroprusside always induced seizures and significantly increased release of aspartate and adenosine during washout of sodium nitroprusside. Diethyldithiocarbamate (5 mM) reversed the effects of sodium nitroprusside. Dithiothreitol (1 mM) significantly reduced the increase in adenosine release by sodium nitroprusside. These findings indicate that adenosine release is closely related to development of seizures, which are triggered by an increase in both NO itself and in part peroxynitrite, which results in reaction with superoxide radicals.

Effect of extracellular calcium on the gene expression of bone morphogenetic protein-2 and -4 of normal human bone cells

A high extracellular calcium level inhibits the formation of osteoclast-like cells and stimulates osteoblastic proliferation, indicating that extracellular calcium plays an important role in the process of bone remodeling. The present study examined the effects of a high extracellular calcium level on mRNA levels of bone morphogenetic protein (BMP)-2 and -4, which are well-documented osteoinductive proteins, and the differentiation of normal human mandible-derived bone cells in vitro. High extracellular calcium significantly increased cell proliferation at an optimal dose of 0.4mM CaCl2 added to control medium containing 1.8 mM CaCl2. The addition of 0.1-0.4mM CaCl2 markedly increased the mRNA levels of BMP-2 and -4 following incubation for 0.5 and 24 h as evaluated by reverse transcription-polymerase chain reaction. While an increased extracellular calcium level (addition of 0.1-1.2mM CaCl2) failed to increase alkaline phosphatase activity and osteocalcin secretion, it did significantly increase type I collagen synthesis, monitored by the production of procollagen type I carboxy-terminal peptide. These results indicate that the extracellular calcium level regulates BMPs and type I collagen synthesis in osteoblastic cells.

The clinical significance of tumor-associated antigen RCAS1 expression in the normal, hyperplastic, and malignant uterine endometrium

OBJECTIVE

A tumor-associated antigen, RCAS1, is recognized by 22-1-1 monoclonal antibody. It was found in carcinomas derived from the uterus and ovary and was especially strongly expressed in invasive cancers. A previous investigation showed the RCAS1 expression to be correlated with a poor prognosis in uterine cervical adenocarcinoma. In this study, we examined whether the expression of RCAS1 is associated with the progression of the uterine endometrial neoplasms.

METHODS

The expression of RCAS1 was evaluated by an immunohistochemical analysis. The tissue specimens used in this study included 46 cases of normal uterine endometrium, 40 cases of hyperplasia, and 121 cases of adenocarcinoma. The relationship between RCAS1 expression and several clinicopathological variables (clinical stage, histology, grade, myometrial invasion, lymph-vascular space invasion, and lymph node metastasis) was also assessed in endometrial adenocarcinoma.

RESULTS

RCAS1 was positive in 26% of the normal uterine endometrium specimens (12 of 46 total cases), in 32% of the hyperplasia specimens (13 of 40 total cases), and in 68% of the adenocarcinoma specimens (83 of 121 total cases). As a result, the expression of RCAS1 was statistically higher in adenocarcinoma than in the normal and hyperplastic endometrium (P < 0.0001). RCAS1 was statistically detected more frequently in grade 3 than in grade 1 or 2 (P < 0.05); however, there was no correlation between the antigen expression and the clinical stage, myometrial invasion, lymph-vascular space invasion, or lymph node metastasis.

CONCLUSION

RCAS1 expression might thus be associated with the malignant transformation and poor differentiation observed in uterine endometrial adenocarcinoma.

Prognostic factors in ovarian carcinosarcoma: a clinicopathological and immunohistochemical analysis of 23 cases

Carcinosarcoma of the ovary is a rare, highly aggressive neoplasm comprising histologically of both epithelial and mesenchymal components. The aim of this study was to evaluate the clinicopathological prognostic factors in ovarian carcinosarcoma, including the immunohistochemical expression of p53 protein and Ki67.

METHODS AND RESULTS

Twenty-three cases of carcinosarcoma of the ovary were studied retrospectively. The clinicopathological and immunohistochemical parameters including p53 and Ki67 staining were statistically analysed to investigate the prognostic significance of this tumour. The overall 5-year survival rate was 27.1%; 100% for stage I, 31.3% for stage II, 10.9% for stage III and 0% for stage IV. The low-stage group (stages I and II) was found to be a significant prognostic factor for patient survival (P = 0.0113). None of the other factors (tumour size, histological type of carcinomatous and sarcomatous components, mitotic count, vascular space invasion and immunoreactivity for p53 protein and Ki6 7) was found to be a statistically significant prognostic indicator.

CONCLUSIONS

Ovarian carcinosarcoma is a rare malignancy with poor prognosis. In this study, advanced stage appears to be poor prognostic indicator of survival in patients with ovarian carcinosarcoma.

Evidence for the involvement of bone morphogenetic protein-2 in phenytoin-stimulated osteocalcin secretion in human bone cells

Recent work has shown that the actions of phenytoin on bone cell proliferation and differentiation are, in part, mediated through the upregulation of transforming growth factor-beta1 (TGF-beta(1)). The present study was undertaken to examine the effect of phenytoin on bone morphogenetic proteins (BMP)-2 and -4, which are well-recognized osteoinductive proteins of the TGF-beta superfamily, in osteoblastic cells. Treatment with 5-50 microM of phenytoin increased the amount of mRNA for BMP-2 after a 0.5-24 h incubation in normal human mandible-derived bone cells (HOB-M cells), but failed to affect the mRNA for BMP-4. Phenytoin treatment for 48 h significantly increased the secretion of BMP-2 by approx. four-fold, at an optimal concentration of 10 microM. While TGF-beta(1) inhibited osteocalcin secretion from HOB-M cells, both phenytoin and BMP-2 significantly stimulated it. Importantly, the stimulatory effects of phenytoin on osteocalcin release were completely blocked by the neutralizing antihuman BMP-2 monoclonal antibody. These results indicate that the stimulatory action of phenytoin on osteocalcin secretion in normal human bone cells is mediated, at least partly, through the upregulation of BMP-2, rather than that of TGF-beta(1).

Pulsed electromagnetic fields promote bone formation around dental implants inserted into the femur of rabbits

The present study examined the effect of applying a pulsed electromagnetic field (PEMF) on bone formation around a rough-surfaced dental implant. A dental implant was inserted into the femur of Japanese white rabbits bilaterally. A PEMF with a pulse width of 25 microseconds and a pulse frequency of 100 Hz was applied. PEMF stimulation was applied for 4 h or 8 h per day, at a magnetic intensity of 0.2 mT, 0.3 mT or 0.8 mT. The animals were sacrificed 1, 2 or 4 weeks after implantation. After staining the resin sections with 2% basic fuchsin and 0.1% methylene blue, newly formed bone around the implant on tissue sections was evaluated by computer image analysis. The bone contact ratios of the PEMF-treated femurs were significantly larger than those of the control groups. Both the bone contact ratio and bone area ratio of the 0.2 mT- and 0.3 mT-treated femurs were significantly larger than the respective value of the 0.8 mT-treated femurs (P < 0.001). No significant difference in bone contact ratio or bone area ratio was observed whether PEMF was applied for 4 h/day or 8 h/day. Although a significantly greater amount of bone had formed around the implant of the 2-week treated femurs than the 1-week treated femurs, no significant difference was observed between the 2-week and 4-week treated femurs. These results suggest that PEMF stimulation may be useful for promoting bone formation around rough-surfaced dental implants. It is important to select the proper magnetic intensity, duration per day, and length of treatment.

Ovarian endometriosis associated with ovarian carcinoma: a clinicopathological and immunohistochemical study

OBJECTIVE

The purpose of this study was to demonstrate the incidence, the histopathological characteristics, and the proliferation activity of endometriosis and atypical endometriosis associated with ovarian carcinoma.

METHODS

Microscopic slides of primary lesions from 127 patients with primary ovarian carcinoma were reviewed. The presence or absence of endometriosis and the transitions from typical endometriosis to atypical endometriosis and from atypical endometriosis to carcinoma were also histologically evaluated. Ki-67 immunoreactivity of typical and atypical endometriosis and carcinoma was examined. In addition, endometrial metaplasias were also evaluated.

RESULTS

Of the 127 patients, 37 had endometriosis: 70% (30/43) had clear cell adenocarcinoma, 43% (3/7) had endometrioid adenocarcinoma, 7% (4/60) had serous adenocarcinoma, and none (0/17) had mucinous adenocarcinoma. Thirty-three cases showed typical endometriosis and 29 cases had atypical endometriosis (25 cases had both). Tufting and the stratification of the lining epithelium were observed in 25 and 23 cases, respectively. The transition from typical endometriosis to atypical endometriosis was observed in 22 cases, and the transition from atypical endometriosis to carcinoma, in 23 cases. Only one case showed a direct transition from typical endometriosis to carcinoma. The mean Ki-67 indices were as follows: ovarian carcinoma, 23.1; atypical endometriosis, 9.9; typical endometriosis, 2.7. In 18 cases with metaplasia in endometriosis, eosinophilic metaplasia and ciliated metaplasia were the most common types. Five cases had two types of metaplasia.

CONCLUSIONS

Ovarian carcinomas, especially clear cell and endometrioid adenocarcinomas, are highly associated with endometriosis. Atypical endometriosis shows proliferation activity intermediate to those of typical endometriosis and ovarian carcinoma, suggesting it is a precancerous status.

Selective block of late currents in the DeltaKPQ Na(+) channel mutant by pilsicainide and lidocaine with distinct mechanisms

The congenital long QT syndrome is an inherited disorder characterized by a delay in cardiac repolarization, leading to lethal cardiac arrhythmias such as torsade de pointes. One form of this disease involves mutations in the voltage-dependent cardiac Na(+) channel, which includes an in-frame deletion of three amino acids (Lys-1505, Pro-1506, and Gln-1507; DeltaKPQ). The potential for selective suppression of the mutant was examined by heterologous expression of DeltaKPQ-Na(+) channels in Chinese hamster fibroblast cells via single-channel recording. In a single-channel cell-attached patch study, DeltaKPQ-Na(+) channels yielded currents that peaked at approximately 1 ms after voltage steps to 0 mV with aberrant late currents, which were composed of burst and isolated openings. The affinity of certain anesthetics (pilsicainide and lidocaine) to the late currents of the mutant channels was examined. It was revealed that 1) pilsicainide (1 microM), an open channel blocker of voltage-dependent Na(+) channels, remarkably decreased the late currents primarily by the shortening of burst duration without suppressing the initial peak current; and 2) lidocaine (1 microM), an inactivated channel blocker, decreased the late currents primarily by the suppression of isolated channel openings. Because the late currents in DeltaKPQ mutants are mainly composed of the burst openings, we conclude that pilsicainide is capable of selectively blocking the late currents in the mutant Na(+) channels that show dominant abnormal burst openings such as in DeltaKPQ mutants.

The grading of lymphovascular space invasion in endometrial carcinoma

BACKGROUND

This study was conducted to elucidate the prognostic significance of a three-grade system for lymphovascular space invasion (LVSI).

METHODS

The prognostic significance of the grading of LVSI as compared with other pathologic variables was evaluated in a study of 303 Japanese women with endometrial carcinoma. The criteria for determining the grade of LVSI were as follows: none (no LVSI), mild (a focus of LVSI was recognized around a tumor), and severe (diffuse or multifocal LVSI were recognized around the tumor or in the myometrium regardless of the degree of myometrial invasion). Both univariate and multivariate regression analyses were performed. The effects of different surgical methods and adjuvant therapies on survival were also examined.

RESULTS

A univariate survival analysis showed that survival significantly correlated with surgical stage, histologic grade, depth of myometrial invasion, LVSI, cervical invasion, ovarian metastasis, and tubal metastasis. Of the three grades of LVSI, survival showed the most difference between the mild and severe groups. In multivariate analysis, the highest correlation with survival was observed for LVSI (P = 0.0008). Lymph node metastasis was also significantly associated with LVSI (P = 0. 0001). The correlation between histologic variables and survival was only slightly influenced by the differences in surgical methods and adjuvant therapies.

CONCLUSIONS

The grading of LVSI was found to be an important histologic prognostic variable. The severe degree of LVSI also was found to be a good indicator of lymph node metastasis. It is therefore important to evaluate the grade of LVSI based on a histologic examination of at least one cut surface of the hysterectomy specimen that macroscopically shows the deepest myometrial invasion.

7-Nitroindazole reduces nitric oxide concentration in rat hippocampus after transient forebrain ischemia

We investigated the effects of 7-nitroindazole, a specific inhibitor of neuronal nitric oxide (NO) synthase, on NO concentration and on blood flow in rat hippocampus after transient forebrain ischemia which was induced by 4-vessel occlusion for 10 min. NO concentration was measured directly by an NO-selective electrode method. Hippocampal blood flow was also estimated by laser Doppler flowmetry. 7-Nitroindazole [0 (vehicle), 12.5, 25, 50 or 100 mg/kg] was administered intraperitoneally 20 min before ischemia. 7-Nitroindazole at any dose used did not affect basal NO levels before ischemia. 7-Nitroindazole (25, 50 and 100 mg/kg) reduced the NO concentration significantly during post-ischemic early reperfusion. Before 10 min of ischemia and during post-ischemic early reperfusion, there were no significant differences in hippocampal basal blood flow and reactive hyperemia between vehicle- and 7-nitroindazole-treated groups. These results demonstrate that the neuronal NO synthase inhibitor, 7-nitroindazole, can effectively inhibit NO synthesis in rat hippocampus during post-ischemic early reperfusion.

Prognostic significance of epithelial-stromal vascular cuffing and microvessel density in squamous cell carcinoma of the uterine cervix

OBJECTIVE

Tumor angiogenesis has been shown to play an important role in tumor growth and metastasis. This study examines the prognostic significance of two histological markers of angiogenesis, i.e., vascular cuffing (VC), a bead-like arrangement of microvessels closely surrounding microscopic tumor nests, and microvessel density (MVD), the number of microvessels in a unit area, in cervical squamous cell carcinoma.

METHODS

One hundred twenty-two specimens from surgically resected uteri with cervical squamous cell carcinoma were histologically reviewed and immunostained for CD34. VC was graded into "none," "incomplete," and "complete." The MVD was determined by counting the microvessels with a light microscope within a x200 field area where neovascularization occurred most actively. Stromal inflammation was also split into three grades. The relationship of VC or MVD to clinicopathological prognostic factors such as FIGO stage, cervical stromal invasion, lymph-vascular space invasion, pelvic lymph node metastasis, and parametrial invasion was evaluated using univariate and multivariate analyses.

RESULTS

The patients with a complete VC pattern showed a significantly worse prognosis compared to those with a pattern graded as either none or incomplete (P<0.011 and P<0.0001, respectively). The Cox regression analysis revealed the complete VC pattern, together with parametrial invasion, to be an independent prognostic indicator for overall survival. MVD and the grading of stromal inflammation showed no significant relationship with VC or overall survival.

CONCLUSIONS

The complete VC pattern may therefore be a useful prognostic indicator in cervical squamous cell carcinoma.

In situ detection of gelatinolytic activity in developing craniofacial tissues

Frozen tissue sections of developing and adult rat heads were incubated on a film coated with a gelatin-containing colloidal silver emulsion in order to detect gelatinolytic activity present in the different tissues. The method, termed film in situ zymography, is based on the ability of the thiol group of the propeptide released from the degraded gelatin to induce a structural change in the colloidal silver and thereby a visible change in color. The frozen tissue sections mounted on the coated film were incubated at 37 degrees C overnight. Gelatinolytic activity was detected as a color change from yellow to red. The activity of gelatinase was completely blocked by phenanthroline, which inhibits matrix metalloproteinases. Gelatinolytic activity was widely present in the oral epithelium, tooth buds, tongue, Meckel's cartilage, salivary glands, and other tissues. The intensity of the gelatinolytic activity varied among the different tissue types. The present study demonstrated gelatinolytic activity in both developing and adult craniofacial tissues. These results suggest that gelatinolytic activity plays an important role in normal turn-over in several tissues. Whereas some of the activity also in the developing rats may be related to this turn-over process, some of it is probably directly associated with developmental changes.

Melatonin stimulates proliferation and type I collagen synthesis in human bone cells in vitro

The pineal secretory product melatonin reportedly regulates release of growth hormone in humans and prevents phototherapy-induced hypocalcemia in newborn rats, suggesting that melatonin affects bone metabolism. Little is known about the effects of melatonin on bone in vitro or in vivo. The present study was undertaken to examine whether melatonin acts directly on normal human bone cells (HOB-M cells) and human osteoblastic cell line (SV-HFO cells) to affect osteogenic action in vitro. The effect of melatonin on bone cell proliferation was determined using the 2,3-bis[2-methoxy-4-nitro-5-sulfophenyl]-2H-tetrazolium-5-carbo xanilide (XTT) assay after a 24 hr incubation with melatonin. Melatonin significantly and dose-dependently increased the proliferation in HOB-M cells and SV-HFO cells by 215 +/- 22.1%, and 193 +/- 6.4%), respectively, with a maximal effect at a concentration of 50 microM. To evaluate the effect of melatonin on bone cell differentiation, alkaline phosphatase (ALP) activity, osteocalcin secretion and procollagen type I c-peptide (PICP) production (a measure of type I collagen synthesis) were measured after a 48 hr treatment. While melatonin at micromolar concentrations did not significantly affect either the ALP activity or the osteocalcin secretion, it significantly and dose-dependently increased the PICP production in HOB-M cells and SV-HFO cells by 983 +/- 42.2%, and 139 +/- 4.2%, respectively, with the maximal stimulatory doses between 50 and 100 microM. These results provide new evidence that melatonin stimulates the proliferation and type I collagen synthesis in human bone cells in vitro, suggesting that melatonin may act to stimulate bone formation.

Pattern of expression of beta-defensins in oral squamous cell carcinoma

Human beta-defensin (hBD)-1 and hBD-2 are antimicrobial peptides that have been detected in certain types of epithelia, including the skin and oral epithelia. It has been suggested that bacterial infection is an important factor in the process of carcinogenesis. The expression of hBDs in oral squamous cell carcinoma (SCC) may be down-regulated. We studied the pattern of expression of hBD-1 and hBD-2 mRNA in oral (SCC) cell lines and in tumor samples obtained from four patients with oral SCC who underwent surgical resection, by reverse transcription-polymerase chain reaction (RT-PCR). Human gingival epithelial (HGE) cells were used as the control. The effect of various inflammatory cytokines on hBD-1 and hBD-2 expression in the HGE cells and SCC cell lines, was also studied. hBD-1 mRNA was detected in the Ca-9, SCC-9 and HSC-4 cell lines, but not in the SAS and KB cell lines. hBD-2 mRNA was detected in all five cell lines. All four tumor samples expressed both hBD-1 and hBD-2 mRNA, although the mRNA level of each protein varied. These results indicate that SCCs in which hBD expression is downregulated, may be susceptible to bacterial infection.