Effects of Cyclic Tensile Forces on the Expression of Vascular Endothelial Growth Factor (VEGF) and Macrophage-colony-stimulating Factor (M-CSF) in Murine Osteoblastic MC3T3-E1 Cells

It has been reported that vascular endothelial growth factor (VEGF), expressed by osteoblasts, can induce osteoclast recruitment and thus affects bone remodeling. The purpose of this study was to investigate the effects of cyclic tensile forces on the expression of VEGF and macrophage-colony-stimulating factor (M-CSF) in osteoblastic MC3T3-E1 cells. VEGF and M-CSF gene expression and protein concentration were determined by real-time PCR and enzyme-linked immunoassay. The expression of VEGF and M-CSF mRNA in the experimental group was higher than in the control group. The increase in the concentration of VEGF and M-CSF protein in the experimental group was time-dependent. Moreover, gadolinium (an S-A channel inhibitor), but not nifedipine (L-Type Ca2+ channel blocker), treatment reduced the concentration of VEGF and M-CSF mRNA and protein in the experimental groups. These findings suggest that cyclic tensile forces increase the expression of VEGF and M-CSF in osteoblastic MC3T3-E1 cells via a stretch-activated channel (S-A channel).

Regeneration of Condyle with a Functional Appliance

Condylar regeneration with the use of functional appliances after condylectomy has been validated. However, the process during treatment remains unclear. In this study, we evaluated the condylar regeneration process and then examined mandibular growth and masticatory muscle activity after regeneration in growing rats. Seventy-five male Wistar rats aged 4 weeks were equally divided into 3 groups: unilateral condylectomy group, unilateral condylectomy + appliance group, or control group. The use of a functional appliance following condylectomy promoted mandibular growth and regeneration of the condyle 1 week after condylectomy. Condyle regeneration showing normal morphology was finally achieved 8 weeks after condylectomy. Asymmetrical masticatory muscle activity was observed after condylectomy. However, the use of a functional appliance produced symmetrical masticatory muscle activity. These results indicate a favorable regeneration process in the condylectomized area due to the use of a functional appliance. In addition, due to condylar regeneration, symmetrical masticatory muscle activity was achieved.

Cryopreservation of osteoblasts by use of a programmed freezer with a magnetic field

In order to determine a suitable condition for osteoblasts cryopreservation, murine osteoblasts were freezed by programmed freezer with a magnetic field (CAS freezer). After 7 days cryopreservation at -150°, the number of survival cells immediately after thawing and the growth rate of cultured cells for 48 hours were examined. Gene and protein expression of alkaline phosphatase (ALP), osteopontin (OPN) and bone sialoprotein (BSP) were compared between cryopreserved and non-cryopreserved groups. As a result, a plunging temperature of -30°, a hold-time at -5° for 15 minutes and a 0.1 mT of magnetic field led to the largest survival and growth rate. Moreover, there was no significant difference in ALP, OPN and BSP mRNA and protein expression between cryopreserved and control groups. From these results, it was suggested that the CAS freezer is available for osteoblast cryopreservation and bone tissue banking can be established in the future.

Mandibular and femoral growth alteration after sex hormone disruption in growing mice

OBJECTIVES

To investigate how mandibular and femoral growth is affected when sex hormone- specific receptor antagonist is administered in growing mice.

MATERIALS AND METHODS

Forty C57BL/6J mice were used in this experiment. At 5 days of age, the mice received daily injection of estrogen receptor alpha (ERα), beta (ERβ), or androgen receptor (AR) antagonists, and their body weight was assessed every 4 days. One, four and eight weeks after the initial injection, radiographs of the mandible and femur were taken and measured. Analyses of variance and pairwise comparisons (Fisher) were performed to examine the differences in values measured among the groups.

RESULTS

Mandibular growth was affected by ERβ antagonist injection in male mice at 4 and 8 weeks. In female mice, the growth was affected during all the experimental period, when ERβ was administered. Moreover, at 8 weeks, mandibular growth was also affected in male and female mice injected with ERα antagonist and in male mice injected with AR antagonist. Femoral growth was affected during all the experimental period in male and female mice injected with ERβ antagonist. Moreover, at 8 weeks, the growth was affected in male and female mice injected with ERα antagonist and in male mice injected with AR antagonist.

CONCLUSIONS

Growth of the mandible and femur in mice, in part, is induced in response to the stimulation of ERβ in chondrocytes before and during early puberty. In late and after puberty, the growth is induced by the stimulation of ERα in male and female mice and that of AR in male mice.

Sex hormones receptors play a crucial role in the control of femoral and mandibular growth in newborn mice

Sex hormones are important for bone growth. However, the mechanism by which sex hormone receptors influence bone growth remains unclear. In orthodontic treatment, there is a need to develop an indicator of bone maturity to accurately predict the beginning and end of growth. This indicator might be developed from the screening of sex hormones. The purpose of this study was to investigate the role of each sex hormone receptor on bone growth in newborn mice. Five-day-old C57BL/6J mice were used in this experiment. Forty mice underwent an orchiectomy (ORX), ovariectomy (OVX), or sham surgery. One week after surgery, the femur and the mandible were resected for immunohistochemical staining. Alternatively, 80 mice were daily injected with antagonist against receptors oestrogen alpha (ERα), beta (ERβ), or androgen receptor (AR). One week after the first injection, radiographs of the femur and mandible were taken and then measured. Analysis of variance and pairwise comparisons (Fisher) were performed to examine the differences in values measured among the groups In the sham-operated male and female mice, ERβ was found to be more prominent than ERα and AR during all experimental periods. In the ORX and OVX groups, the expressions of all receptors were significantly reduced in comparison with the sham-operated control group throughout the experiment. Moreover, femur and mandibular growth were significantly affected in the group injected with ERβ antagonist. The deficiency of any sex hormone leads to reduced bone growth. In particular, a disturbance in ERβ produces a greater aberrance in both male and female mice immediately after birth.

Cryopreservation of periodontal ligament cells with magnetic field for tooth banking

The purpose of this study was to establish a long-term tooth cryopreservation method that can be used for tooth autotransplantation. Human periodontal ligament (PDL) cells were frozen in 10% dimethyl sulfoxide (Me(2)SO) using a programmed freezer with a magnetic field. Cells were cryopreserved for 7 days at -150 degrees C. Immediately after thawing, the number of surviving cells was counted and the cells were cultured; cultured cells were examined after 48 h. Results indicated that a 0.01 mT of a magnetic field, a 15-min hold-time, and a plunging temperature of -30 degrees C led to the greatest survival rate of PDL cells. Based on these findings, whole teeth were cryopreserved under the same conditions for 1 year. The organ culture revealed that the PDL cells of cryopreserved tooth with a magnetic field could proliferate as much as a fresh tooth, although the cells did not appear in the cryopreserved tooth without a magnetic field. Histological examination and the transmission electron microscopic image of cryopreserved tooth with a magnetic field did not show any destruction of cryopreserved cells. In contrast, severe cell damage was seen in cells frozen without a magnetic field. These results indicated that a magnetic field programmed freezer is available for tooth cryopreservation.

Correction of severe open bite using miniscrew anchorage

This report describes the treatment of a case of severe open bite with posterior crossbite. While treating open bite, the outcome may not always be successful with orthodontic therapy alone. In such cases, surgical therapy is often chosen to gain a stable occlusion. Skeletal anchorage systems such as miniscrews are now frequently used for correcting severe malocclusion. In this report, we treated an open bite by intruding the molars with miniscrews placed bilaterally in the interdental space between both the upper and lower posterior teeth. The active treatment period was 36 months and the patient's teeth continued to be stable after a retention period of 36 months.

Effects of Mandibular Advancement on Growth after Condylectomy

Previous studies have indicated that an injured condyle during adolescence is a causative factor for reduced mandibular growth and resulting asymmetry of the mandible. The aim of this study was to examine the nature of mandibular growth after unilateral condylectomy and to elucidate the effects of mandibular advancement. Sixty growing mice were subjected to unilateral condylectomy, and then one-half of them underwent treatment with a functional appliance. After 4 wks, a unilateral condylectomy produced reduced growth of the mandible and a subsequent lateral shift to the affected side. However, reduced growth and a lateral shift of the mandible were eliminated by a functional appliance, and prominent regeneration of the condyle was also demonstrated. It was shown that mandibular advancement provides for the regeneration of cartilaginous tissues on injured condyles and recovery of reduced mandibular growth, leading to correction of the lateral shift of the mandible.

Amyloid beta protein deposition in osteopetrotic (op/op) mice is reduced by injections of macrophage colony stimulating factor

The deposition of amyloid beta (Abeta) protein is a neuropathological change that characterizes Alzheimer's disease. Animals with the osteopetrosis (op/op) mutation suffer from a general skeletal sclerosis, a significantly reduced number of macrophages and osteoclasts in various tissues, and have no systemic macrophage colony stimulating factor (M-CSF). This study examined the effect that M-CSF injections had on Abeta deposition and microglial cell distribution in the brains of normal and op/op mice. Abeta-positive plaques were detected in the cerebral cortex of op/op mice, but not in normal mice. M-CSF reduced the numbers of Abeta-positive plaques in op/op mice. The microglial cell population was reduced in op/op mice compared with normal mice, and M-CSF increased the numbers to 65.8% of that observed in normal mice. Our results suggest that a clearer understanding of the role that microglial cells play in Abeta deposition may help determine the mechanisms involved in the pathogenesis of Alzheimer's disease.

Influence of sex hormone disturbances on the internal structure of the mandible in newborn mice

It has not yet been clarified how sex hormones affect craniofacial bone development immediately after birth. The purpose of this study was to examine the effects of sex hormone deficiency on craniofacial bone development immediately after birth, in terms of the internal structure of the mandible in newborn mice with orchiectomy (ORX) and ovariectomy (OVX). ORX, OVX and a sham-operation were performed on 40 five-day-old C57BL/6J mice. Eight weeks after surgery, each mandible was subjected to histomorphometric analysis of trabecular (Tr) and cortical (Ct) bone mineral density (BMD) by peripheral quantitative computed tomography (pQCT). In the experimental groups, a significant reduction in BMD was found in comparison with the control groups. In histomorphometric analysis, the number of tartrate-resistant acid phosphatase (TRAP)-positive cells in the condyle and the thickness of the condylar cartilage layer was significantly greater in the experimental mice than in the controls. Trabecular bone volume of the condyle measured on azocarmine-aniline blue (AZAN) sections was significantly less in the experimental mice than in the controls. These results indicate that mandibular growth is inhibited by sex hormone disturbances and the relevant internal structures changed. The findings show that sex hormones are one of the key determinants of mandibular growth and development immediately after birth.

Effects of sex hormone disturbances on craniofacial growth in newborn mice

It is well-known that sex hormones influence bone metabolism. However, it remains unclear as to how sex hormones affect bone growth in newborn mice. In this study, we performed orchiectomy (ORX) and ovariectomy (OVX) on newborn mice, and examined the effects on craniofacial growth morphometrically. ORX and OVX were performed on five-day-old C57BL/6J mice. Four weeks after surgery, lateral cephalograms were taken of all of the mice, with the use of a rat and mouse cephalometer. Cephalometric analysis of the craniofacial skeleton was performed by means of a personal computer. Inhibition of craniofacial growth was found in the experimental groups but not in the sham-operated groups. In the nasomaxillary bone and mandible, the amount of growth was significantly reduced. These results suggest that craniofacial growth is inhibited by sex hormone disturbances not only in puberty but also immediately after birth.

Expression of vascular endothelial growth factor and the effects on bone remodeling during experimental tooth movement

Vascular endothelial growth factor (VEGF) has an ability to induce functional osteoclasts as well as neovascularization. We recently reported that the number of osteoclasts was enhanced by the injection of recombinant human VEGF (rhVEGF) with the application of mechanical force for experimental tooth movement. In this study, the expression of VEGF was detected in osteoblasts on the tension side of the alveolar bone. Moreover, the rate of tooth movement was significantly increased in the rhVEGF injection groups compared with the controls. These results suggested that VEGF, highly expressed by mechanical stimuli, enhances the number of osteoclasts as a paracrine factor, and that the amount of tooth movement is accelerated by both endogenous VEGF and injected rhVEGF.

Effects of insulin-like growth factor-I on the expression of osteoclasts and osteoblasts in the nasopremaxillary suture under different masticatory loading conditions in growing mice

It is well accepted that mechanical loading inhibits bone resorption and increases in vivo bone formation. It is also known that cyclic mechanical loading, in particular, can enhance bone formation significantly. These findings suggest a significant role for mechanical stimuli in bone remodelling mediated by various local growth factors including insulin-like growth factor-I (IGF-I). Earlier studies showed that the nasal bone length and premaxillary bone width were significantly greater in mice fed a solid diet rather than a granulated diet, and that these dimensions increased significantly in a solid-diet group treated with IGF-I. The present study sought to examine the effect of IGF-I on the expression of osteoclasts and osteoblasts in the nasopremaxillary suture subjected to different masticatory loadings. For the solid-diet groups, the numbers of tartrate-resistant acid phosphatase (TRAP)-positive osteoclastic cells and osteoblasts were significantly greater in the group injected with IGF-I than in the animals injected with physiological saline. In the groups fed a granulated diet, no significant differences in the numbers of TRAP-positive osteoclastic cells and osteoblasts were found over the entire experimental period between mice injected with either IGF-I or physiological saline. It is shown that IGF-I significantly induces the expression of osteoclasts and osteoblasts and the subsequent bone remodelling, and that the effect may be additive as compared to that of mechanical masticatory loading, which seems to be more important in bone remodelling in terms of the numbers of osteoclasts and osteoblasts.

Seasonal changes in the freezing behavior of xylem ray parenchyma cells in four boreal hardwood species

The freezing behavior of xylem ray parenchyma cells in several boreal hardwood species, namely, Betula platyphylla, Populus canadensis, P. sieboldii, and Salix sachalinensis, was examined by differential thermal analysis (DTA), cryo-scanning electron microscopy (Cryo-SEM), and freeze-fracture replica electron microscopy. Although DTA profiles of samples harvested in summer and in winter suggested that the xylem ray parenchyma cells in all four species responded to freezing stress by extracellular freezing, Cryo-SEM showed clearly that the xylem ray parenchyma cells in all these species responded to freezing stress by shallow supercooling in summer and by extracellular freezing in winter. It is suggested that DTA failed to reveal the true freezing behavior of xylem ray parenchyma cells because of an overlap of temperature ranges between the high-temperature exotherm and the low-temperature exotherm and/or because of the limited extent of the LTE. The seasonal changes in freezing behavior of xylem ray parenchyma cells in all these boreal species, which are results of seasonal cold acclimation, support the hypothesis that a gradual shift of freezing behavior in xylem ray parenchyma cells from shallow supercooling in hardwood species that grow in tropical zones to extracellular freezing in hardwood species that grow in cold areas might be a result of the evolutionary adaptation of hardwood species to cold climates. Copyright 1999 Academic Press.

Intraoral minor salivary gland tumors: a retrospective study of 129 cases

From 1970 to 1996, 129 cases of intraoral minor salivary gland tumors were diagnosed at the Department of Pathology, Nihon University School of Dentistry. The diagnosis of each case was based on the 1991 WHO classification. Eighty benign and 49 malignant minor salivary gland tumors were found in the approximately 9,300 oral biopsies submitted during the 27-year period. Pleomorphic adenomas were the most commonly histologic type of the benign tumors identified and 51% of the malignant tumors were diagnosed as mucoepidermoid carcinoma. The most common primary location of the tumors was the palate. Sixty percent of all tumors occurred in females and the peak age for incidences of all tumors was found in the third, fourth, sixth and seventh decades. These results were compared with those of the studies in different world population groups.

Actions and cross-reactivity of antiallergic agents and a calcium channel antagonist on rat peritoneal mast cells. Difference in the action mechanisms and cross-reactivity among the agents

The actions of the antiallergic agents, disodium chromoglycate (DSCG), tranilast and ketotifen, and of a calcium channel antagonist, nicardipine, and cross-reactivity among the agents were examined by observing the inhibition of 45Ca uptake and histamine release in rat mast cells stimulated by antigen and compound 48/80 (comp. 48/80). 1) All agents inhibited 45Ca uptake and histamine release in mast cells stimulated by antigen. The inhibition of 45Ca uptake by the antiallergic agents paralleled the inhibition of histamine release, while nicardipine inhibition of 45Ca uptake was stronger than its inhibition of histamine release. 2) The action of DSCG on 45Ca uptake and histamine release was significantly decreased in cells stimulated with antigen and phosphatidylserine (PS), while tranilast inhibition of histamine release was not affected by the addition of PS despite a significant decrease in the inhibition of 45Ca uptake. 3) The inhibitory effect of DSCG and tranilast was significantly lower in mast cells stimulated by comp. 48/80 than in the cells stimulated by antigen. 4) Tachyphylaxis was observed in cells re-exposed to DSCG and tranilast following previous exposure to the agents. 5) Cross-reactivity was found between DSCG and tranilast.

Spectroscopic study on interaction of nucleic acid base with tryptophan-containing tripeptides: acetyl-Trp-X-Trp-NHCH3 (X = Gly, Asn, Asp, Gln and Glu)

As part of a series of peptides designed to have binding ability selective for each of the nucleic acid bases, five tripeptides consisting of N-acetyl-Trp-X-Trp-NHCH3 (X = Gly, Asn, Asp, Gln and Glu) were synthesized, and their abilities to form complexes with four different nucleotides were examined by the fluorescence and phase distribution methods. The association constants obtained indicated that, depending on the sort of X residue, the peptides showed a variation in their interaction with guanosine monophosphate (GMP), while no noticeable selectivity was observed for other nucleotides adenosine monophosphate (AMP), uridine monophosphate (UMP) and cytidine monophosphate (CMP). The binding mode of N-acetyl-Trp-Asp-Trp-NHCH3 for the guanine base was further investigated using the proton nuclear magnetic resonance (1H-NMR) method. The mode was suggested to involve intimate cooperation of (1) the hydrogen bond formation between the carboxyl group of the Asp side chain and the guanine C2-amino group, and (2) the stacking interaction of the base with two terminal Trp residues of the peptide. Such interaction was strengthened by the protonation of the guanine base. A tentative binding mode is proposed based on these results.

The calcium antagonist, nicardipine, inhibits antigen-stimulated and anti-IgE-induced histamine release from basophilic leucocytes of atopic asthmatics

The inhibitory effect of nicardipine, a calcium antagonist, on the antigen- and anti-IgE-induced histamine release from basophilic leucocytes of patients with bronchial asthma was examined. The agent significantly inhibited both antigen-stimulated and anti-IgE-induced histamine release from basophils (the maximum percent inhibition was 57.8 +/- 7.2% and 56.0 +/- 8.8%, respectively). Pre-incubation of basophils with nicardipine for periods of up to 120 min did not alter the inhibitory effect. These results suggest that nicardipine modifies the histamine release from basophils which closely participate in an attack of bronchial asthma.

Inhibitory effect of the CA2+ antagonist nifedipine on histamine release from rat peritoneal mast cells

45Ca uptake and histamine release was examined in mast cells from rats sensitized with ovalbumin and Bordetella Bertussis as an adjuvant. The uptake of 45Ca by the mast cells was significantly increased by stimulation with ovalbumin as was the release of histamine from the mast cells. Nifedipine, a calcium antagonist, inhibited the increase in both 45Ca uptake and histamine release stimulated by ovalbumin, though the effect on 45Ca uptake was stronger than that on histamine release.