Localization of sense and antisense transcripts of Prdx2 gene in mouse tissues

Recently, it has been reported that antisense RNAs are transcribed from a large number of genes in various species including human and mouse. The Prdx2 gene, which is indicated to be involved in signal transduction related to platelet-derived growth factor as well as to protection from oxidizing agents, has been shown to produce sense and antisense transcripts. To obtain clues for possible roles of Prdx2 antisense transcripts, we have performed Northern blot analysis and in situ hybridization on tissues of 8-week-old C57BL/6J mice. The Northern blot analysis revealed that major parts of sense and antisense transcripts were poly(A-)-RNA. The analysis of the fractionated RNA of fibroblasts indicated that the poly(A-)-RNA would be localized in the cytoplasm of cells. The in situ hybridization demonstrated that the sense and antisense transcripts were localized in almost the same limited areas of brain, testis, and spleen. It also revealed that the sense and antisense transcripts coexisted in Purkinje cells. In thymus and stomach, the antisense transcripts were detected, but sense transcripts were not. When tissues of BALB/c mice were examined by in situ hybridization, the observations were essentially the same as those of C57BL/6J except that it appeared that the amounts of sense and antisense transcripts in testis of BALB/c were greater than those in C57BL/6J, and that the amounts of antisense transcripts in stomach of BALB/c were much smaller than those in C57BL/6J.

Local osteoprotegerin gene transfer to periodontal tissue inhibits lipopolysaccharide-induced alveolar bone resorption

BACKGROUND AND OBJECTIVE

Osteoclastogenesis is primarily activated by receptor activator of nuclear factor kappaB ligand (RANKL) and is inhibited by osteoprotegerin (OPG). A previous study demonstrated that local OPG gene transfer to periodontal tissue inhibited RANKL-mediated osteoclastogenesis and experimental tooth movement. In the present study, we tested the hypothesis that local OPG gene transfer to the periodontium can neutralize RANKL activity induced by lipopolysaccharide injection, thereby inhibiting osteoclastogenesis and diminishing alveolar bone resorption in experimental periodontal disease.

MATERIAL AND METHODS

Seven-week-old male Wistar rats received an injection of lipopolysaccharide or phosphate-buffered saline in the palatal gingiva of the upper first molars on both the right and left sides. An inactivated haemagglutinating virus of Japan (HVJ) envelope vector containing a mouse OPG expression plasmid [pcDNA3.1(+)-mOPG] or mock vector was injected periodically into the palatal periodontal tissue of the upper first molars.

RESULTS

Lipopolysaccharide injection induced severe periodontal bone resorption. Local OPG gene transfer induced OPG production, and osteoclastogenesis was inhibited. Local OPG gene transfer significantly decreased alveolar bone resorption.

CONCLUSION

Osteoprotegerin gene transfer to periodontal tissue inhibited osteoclastogenesis and alveolar bone resorption in lipopolysaccharide-induced experimental periodontal disease.

Longitudinal MRI follow-up of non-reducible posterior disc displacement accompanied by bone marrow oedema in the mandibular condyle

Serial MRI was used to examine the long-term course of posterior disc displacement (PDD) after non-surgical treatment. Serial MRI was performed on a 63-year-old woman with PDD accompanied by bone marrow oedema (BME) in the mandibular condyle. The patient had joint pain of the right temporomandibular joint (TMJ) and posterior open bite immediately after manual reduction of TMJ dislocation. Initial MRI of the right TMJ showed non-reducible PDD and subchondral BME. The patient underwent non-surgical treatment, and symptoms improved. The first follow-up MRI after 5 months showed non-reducible PDD, expansion of BME and erosion of the mandibular condyle. 1 year and 8 months after the initial examination the patient was asymptomatic, and a second follow-up MRI showed resolution of both BME and erosion, despite the persistence of non-reducible PDD. The MRI findings suggest that BME in the mandibular condyle complicating PDD is a reversible change, and may contribute to joint pain. This case report complements previous observations of the longitudinal course of PDD after non-surgical treatment.

Association between high signal intensity in the posterior disc attachment seen on T2 weighted fat-suppressed images and temporomandibular joint pain

OBJECTIVES

We sought to determine whether high signal intensity in the posterior disc attachment (PDA) seen on T2 weighted fat-suppressed MRI is associated with temporomandibular joint (TMJ) pain and joint pathology.

METHODS

This study was based on 283 TMJs of 177 patients (31 males and 146 females, mean age 32.7 years) with TMJ disorders showing anterior disc displacement. MRI evaluation included assessment of signal intensity in the PDA and TMJ status (disc displacement with reduction, disc displacement without reduction and disc displacement with bone changes). Clinical criteria that were considered positive indicators of TMJ pain included the presence of pre-auricular pain during palpation, jaw function and assisted or unassisted mandibular opening. Association of signal intensity in the PDA with joint pain and TMJ status was analysed using chi2 test.

RESULTS

Joint pain was reported in 47 (77.0%) out of 61 joints with high signal intensity in the PDA and in 97 (43.7%) out of 222 joints with low signal intensity in the PDA (P<0.0001). High signal intensity in the PDA correlated closely with more advanced joint pathology. In joints with anterior disc displacement with bone changes, TMJ pain was more commonly reported in joints with high signal intensity in the PDA than with low signal intensity in the PDA (P<0.0001).

CONCLUSIONS

High signal intensity in the PDA on T2 weighted fat-suppressed MRI is associated with TMJ pain in TMJ disorders with anterior disc displacement with bone changes in the mandibular condyles.

Carotid artery calcification seen on panoramic dental radiographs in the Asian population in Japan

OBJECTIVES

To determine the frequency of carotid artery calcification (CAC) seen on panoramic dental radiographs, the relationship between the condition and a history of cerebral infarction (CI), and the history of the risk factors of CI in patients in Japan.

METHODS

A total of 2374 individuals whose panoramic radiographs were obtained at their first consultation were reviewed.

RESULT

CAC was found in 95 subjects (4.0%) and was found at a higher frequency in patients with a history of CI than in those without a history of CI. The modifiable risk factors (a history of hypertension, diabetes and hypercholesterolaemia) and CAC showed significant relationship in the chi(2) test for pairwise comparison. When age and gender were added and all of these risk factors were considered simultaneously in the multiple logistic regression analysis, age and history of hypercholesterolaemia remained statistically significant.

CONCLUSIONS

CAC may be seen on panoramic dental radiographs and is related to the patients' general history of CI, and the risk factors of CI in the Asian population in Japan.

Clodronate inhibits PGE(2) production in compressed periodontal ligament cells

Periodontal ligament (PDL) cells play an essential role in orthodontic tooth movement. We recently reported that clodronate, a non-N-containing bisphosphonate, strongly inhibited tooth movement in rats, and thus could be a useful adjunct for orthodontic treatment. However, it is not clear how clodronate affects the responses of PDL cells to orthodontic force. In this study, we hypothesized that clodronate prevents the mechanical stress-induced production of prostaglandin E(2) (PGE(2)), interleukin-1beta (IL-1beta), and nitric oxide (NO) in human PDL cells. A compressive stimulus caused a striking increase in PGE(2) production, while the responses of IL-1beta and NO were less marked. Clodronate concentration-dependently inhibited the stress-induced production of PGE(2). Clodronate also strongly inhibited stress-induced gene expression for COX-2 and RANKL. These results suggest that the inhibitory effects of clodronate on tooth movement and osteoclasts may be due, at least in part, to the inhibition of COX-2-dependent PGE(2) production and RANKL expression in PDL cells.

Cyclical tensile force on periodontal ligament cells inhibits osteoclastogenesis through OPG induction

The periodontal ligament (PDL) maintains homeostasis of periodontal tissue under mechanical tensile-loading caused by mastication. Occlusal load inhibits atrophic alveolar bone resorption. Previously, we discovered that continuous compressive force on PDL cells induced osteoclastogenesis-supporting activity, with up-regulation of RANKL. We hypothesized that, unlike compression, cyclical tensile force up-regulates OPG expression in PDL cells via TGF-beta up-regulation, and does not induce osteoclastogenesis-supporting activity. PDL cells were mechanically stimulated by cyclical tensile force in vitro. The conditioned media of PDL cells that had been subjected to cyclical tensile force inhibited osteoclastogenesis. Cyclical tensile force up-regulated not only RANKL mRNA expression, but also OPG mRNA expression in PDL cells. Tensile force up-regulated TGF-beta expression in PDL cells as well. Administration of neutralizing antibodies to TGF-beta inhibited OPG up-regulation under cyclical tensile-force stimulation in a dose-dependent manner. Additionally, the osteoclastogenesis-inhibitory effect of the conditioned media of PDL cells under cyclical tensile force was partially rescued by the administration of TGF-beta neutralizing antibodies. In conclusion, tensile force inhibited the osteoclastogenesis-supporting activity of PDL cells by inducing the up-regulation of OPG via TGF-beta stimulation.

Local RANKL gene transfer to the periodontal tissue accelerates orthodontic tooth movement

It has been reported that not only selective alveolar-bone resorption, but also receptor activator of nuclear factor kappa B ligand (RANKL) expression is induced on the compressed side of an orthodontically moving tooth. Numerous reports have described the pharmacological acceleration of tooth movement (TM) through the activation of osteoclasts. However, because of rapid flush out by blood circulation, daily systemic administration or daily local injection is needed. Previously, we discovered that every-3-days OPG gene transfer to the periodontal-tissue inhibited RANKL-mediated osteoclastogenesis and diminished experimental TM. Therefore, we hypothesized that local RANKL gene transfer into the periodontal tissue would accelerate TM. The upper first molars of 6-week-old male Wistar rats were moved palatally using fixed orthodontic wires. The inactivated hemagglutinating-virus of Japan (HVJ) envelope vector containing the mouse RANKL expression plasmid was injected periodically into the palatal periodontal tissue of the upper first molars during TM. Local RANKL gene transfer significantly enhanced RANKL expression and osteoclastogenesis in periodontal tissue without any systemic effects. The TM rate was significantly increased in the RANKL gene transfer side. In conclusion, we demonstrated that transfer of the RANKL gene to the periodontal-tissue activated osteoclastogenesis and accelerated the amount of experimental TM. Local RANKL gene transfer might be a useful tool not only for shortening orthodontic treatment, but also for moving ankylosed teeth where teeth, fuse to the surrounding bone.

Clinical diagnostic indicators of renal and bone damage in rats intramuscularly injected with depleted uranium

The toxic effects and changes in biochemical markers related to kidney and bone in depleted uranium (DU)-injected rats were examined in order to clarify the relation between clinical biochemical markers and the degree of damage in these organs. Male Wistar rats received a single injection in the femoral muscles of 0.2, 1.0 or 2.0 mg kg(-1) of DU which was dissolved in nitric acid solution adjusted to pH 3.2, for comparison with the group injected with nitric acid solution, and the control group. Urine and faeces were collected periodically over a 24 h period. Thereafter, the rats were killed at 28 d after DU injection. The body weights of the DU-injected groups decreased dose-dependently for the first 3-7 d, and then began to increase. The DU concentrations in the urine and faeces decreased rapidly within 3-7 d after DU injection. Urinary N-acetyl-beta-D-glucosaminidase (NAG)/creatinine peaked at the third day after DU injection, with a high correlation to the injected DU doses. There were high correlations among the injected DU doses, DU concentrations in the kidney and urinary NAG/creatinine values that were obtained at 28 d, respectively. The blood urea nitrogen (BUN) and creatinine in the serum also showed a high correlation with the DU-injected doses. The results indicated that urinary NAG/creatinine, BUN and creatinine in serum were useful indicators to diagnose the renal damage by DU, as well as to estimate the DU intake and concentration in the kidney when the intake is >2 mg kg(-1) DU. The total bone mineral density of the proximal metaphysis of the tibia decreased in the 2 mg kg(-1) DU group. In addition, alterations of the trabecular bone structure by inhibiting bone formation and promoting bone resorption were observed by bone histomorphometery. The bone biochemical markers osteocalcin, tartrate-resistance acid phosphatase, pyridinoline and rat-parathyroid hormone increased in all the DU injected groups, indicating that these markers were useful as sensitive indicators for diagnosing bone damage, even if the DU dose injected is low.

Application of boron-entrapped stealth liposomes to inhibition of growth of tumour cells in the in vivo boron neutron-capture therapy model

Tumour cell destruction in boron neutron-capture therapy (BNCT) is due to the nuclear reaction between (10)B and thermal neutrons. It is necessary for effective BNCT therapy to accumulate (10)B atoms in the tumour cells. The delivery system consisted of polyethylene-glycol (PEG) binding liposomes (DPPC/cholesterol/DSPC-PEG2000) with an entrapped (10)B-compound and we evaluated the cytotoxic effects of intravenously injected (10)B-PEG-liposomes on human pancreatic carcinoma xenografts in nude mice with thermal neutron irradiation. After thermal neutron irradiation of mice injected with (10)B-PEG-liposomes, growth of AsPC-1 tumours was suppressed relative to controls. Injection of (10)B-PEG-liposomes caused the greatest tumour suppression with thermal neutron irradiation in vivo. These results suggest that intravenous injection of (10)B-PEG-liposomes can increase the retention of (10)B atoms by tumour cells, causing suppression of tumour growth in vivo, after thermal neutron irradiation.

The relationship of bone marrow edema pattern in the mandibular condyle with joint pain in patients with temporomandibular joint disorders: longitudinal study with MR imaging

The purpose of this study was to investigate the course of bone marrow edema pattern (decreased signal intensity on T1- or proton-density-weighted images and increased signal intensity on T2-weighted fat-suppressed images) in the mandibular condyle after improvement in clinical symptoms, and to clarify its relationship with temporomandibular joint (TMJ) pain. This study was based on 14 joints of 11 patients (all female, mean age 37.5 years) with TMJ disorders showing condylar bone marrow edema pattern on initial magnetic resonance (MR) images. All joints were re-evaluated clinically and using MR images after relief of joint pain following arthrocentesis combined with non-surgical treatment. The time interval between the initial and follow-up MR images ranged from 14 to 27 months (mean 17 months). Of the 14 joints, 4 joints (28.6%) showed a normal bone marrow signal, whereas 10 joints (71.4%) showed persistent bone marrow edema pattern on follow-up MR images (P = 0.125). Therefore, the reduction in TMJ pain did not correlate with resolution of bone marrow edema pattern in most joints. The results of this study suggest that the bone marrow edema pattern in the mandibular condyle does not always contribute to the occurrence of joint pain in patients with TMJ disorders.

Experimental observation of the 1/3 magnetization plateau in the diamond-chain compound Cu3(CO3)2(OH)2

The magnetic susceptibility, high field magnetization, and specific heat measurements of Cu3(CO3)2(OH)2, which is a model substance for the frustrating diamond spin chain model, have been performed using single crystals. Two broad peaks are observed at around 20 and 5 K in both magnetic susceptibility and specific heat results. The magnetization curve has a clear plateau at one third of the saturation magnetization. The experimental results are examined in terms of theoretical expectations based on exact diagonalization and density matrix renormalization group methods. An origin of magnetic anisotropy is also discussed.

Longitudinal MRI follow-up of temporomandibular joint internal derangement with closed lock after successful disk reduction with mandibular manipulation

We present a case of bilateral temporomandibular joint (TMJ) internal derangement with closed lock, which was followed over 11 years using serial MRI after successful disk reduction with mandibular manipulation. MRI of the bilateral TMJs before and after mandibular manipulation followed by anterior repositioning splint showed that the disk improved from non-reducible to reducible, and that the reducing disk persisted for 11 years, although minor changes in configuration and position of the disk occurred. These MRI findings suggest that non-surgical treatment with successful mandibular manipulation prevents progressive changes in the TMJ. This case report complements observations regarding the longitudinal course of TMJ internal derangement with closed lock after non-surgical treatment.

Local OPG gene transfer to periodontal tissue inhibits orthodontic tooth movement

Previously, we discovered that RANKL expression is induced in compressed periodontal ligament cells, and that this promotes osteoclastogenesis on the compression side in orthodontic tooth movement. We hypothesized that local OPG gene transfer to the periodontium would neutralize the RANKL activity induced by mechanical compressive force, thereby inhibiting osteoclastogenesis and diminishing tooth movement. The upper first molars of six-week-old male Wistar rats were moved palatally by means of a fixed-orthodontic wire. A mouse OPG expression plasmid [pcDNA3.1(+)-mOPG] was constructed, and the production of functional OPG protein was confirmed in vitro. The inactivated HVJ envelope vector containing pcDNA3.1(+)-mOPG or PBS was injected periodically into the palatal periodontal tissue of upper first molars. When this local OPG gene transfer was performed, OPG production was induced, and osteoclastogenesis was inhibited. Local OPG gene transfer significantly diminished tooth movement. In this study, we report that OPG gene transfer to periodontal tissue inhibited RANKL-mediated osteoclastogenesis and inhibited experimental tooth movement.

Effects of alendronate on restoration of biomechanical properties of periodontium in replanted rat molars

OBJECTIVE

We examined the effect of the pretreatment of roots with alendronate on the restoration of the support function of the healing periodontal ligament in replanted rat molars.

METHODS

The left maxillary first molars were extracted, placed in 0.9% NaCl containing 1 mm alendronate (alendronate group) or 0.9% NaCl (control group) for 5 min, and were replanted into their sockets. Groups of animals were killed at 7, 14, and 21 days after replantation. Normal control rats were also killed on the same days. The force required to extract the replanted or normal tooth from its socket was measured, and a load-deformation curve was developed and analyzed. Micro-computed tomography and histologic analyses were also made.

RESULTS

The mechanical properties of the healing periodontal ligament in the alendronate group were gradually restored from 7 to 21 days. However, fractures of the roots and bones during mechanical testing occurred in most of the replanted teeth in the control group at 21 days. The rates of restoration of the mechanical strength, extensibility, stiffness, and toughness for the alendronate group at 21 days were 67, 98, 74, and 68% of the normal controls, respectively. Micro-computed tomography and histologic observations revealed that bone-like structures within the pulp and ankylosis between the roots and socket bones occurred commonly in the control group, but were uncommon in the alendronate group.

CONCLUSIONS

Our findings suggest that the pretreatment with alendronate inhibits the formation of abnormal mineralized tissues and results in better restoration of the support function of the healing periodontal ligament in replanted teeth.

Effects of age on the stress–strain and stress–relaxation properties of the rat molar periodontal ligament

OBJECTIVE

We examined the stress-strain and stress-relaxation properties of the periodontal ligament (PDL) in the rat molar at 2, 6, 12, and 24 months of age to elucidate age-related changes in the tooth support function of the PDL.

DESIGN

From the dissected left and right mandibles in each rat, a pair of transverse sections (ca. 0.45 mm in thickness) of the first molar was cut at the middle part of the mesial root. We then obtained a load-deformation curve for the PDL, using one of the paired sections. The other section was loaded to as much as 50% of the maximum load as determined from the contralateral section, and keeping the deformation constant for 10 min, a load-relaxation curve was obtained and analysed.

RESULTS

The maximum shear stress and tangent modulus decreased between 2 and 24 months of age. As the maximum shear strain increased with age (P < 0.001), the failure strain energy density did not change between 2 and 24 months of age. The stress-relaxation during the 10 min period decreased from 2 to 24 months of age (P < 0.01). The relaxation process of the PDL in each age was well described by a sum of three exponential decay functions. The age-related decrease in the relaxation was found to be mainly due to the increase in the relaxation time for the long-term relaxation component.

CONCLUSION

These results indicate that the maximum shear stress and stiffness of the rat molar PDL decrease between 2 and 24 months of age; but its toughness remains unchanged due to an increase in the extensibility. Our findings further indicate that the fluid flow and movements of macromolecules within the stretched PDL fibres during the stress-relaxation decrease with advancing age.

Cytoskeletal changes and the system of regulation of alkaline phosphatase activity in human periodontal ligament cells induced by mechanical stress

The periodontal ligament (PDL) is a specialized, mechanically responsive tissue that adapts via cellular responses to equilibrate the effects of mechanical stress on teeth. However, the mechanism of remodelling by which individual cells in periodontal tissue detect and respond to mechanical stress is not well understood. To identify the cellular mechanisms induced by mechanical stress in the periodontal ligament, we examined the effects of cyclic stretching on periodontal ligament fibroblast-like cells (PDL cells). Furthermore, we investigated the effects of 1alpha,25-dihydroxyvitamin D(3) (1,25(OH)(2)D(3)), and interaction with peripheral blood mononuclear cells (PBMCs) on mechanically-simulated PDL cells. PDL cells were cultured on type I collagen-coated silicon membranes with 10% FBS alpha-MEM, and then subjected to cyclic mechanical stimulation (1 s stretching/1 s relaxation, 15% maximum elongation). Alkaline phosphatase activity was monitored by cytochemical and spectrophotometric methods. Morphologically, the cells assumed a spindle shape, and the cytoskeletal components, including microtubules and F-actin filaments, were aligned perpendicular to the strain force vector. Cyclic stretching decreased ALPase activity in PDL cells. The anabolic systemic hormone 1,25(OH)(2)D(3) increased ALPase activity, but this effect was suppressed by cyclic stretching. ALPase activities were reduced by co-culture with PBMCs, including lymphocytes and monocytes. This PBMC-induced ALPase reduction was synergistically reduced by cyclic stretching. ALPase activity was decreased by co-culture with PBMCs, and ALPase activity was reduced synergistically by treatment with PBMCs and cyclic stretching. We conclude that PDL cells changed their shape and alignment in response to cyclic stretching. Furthermore, local factors, such as mechanical stress and PBMCs, showed synergistic suppressive effects on ALPase activity.

Age-related and regional differences in the stress–strain and stress–relaxation behaviours of the rat incisor periodontal ligament

Groups of rats were killed at 2, 6, 12, and 24 months of age. From dissected left and right mandibles in each rat, three pairs of transverse sections were cut at the incisal, middle, and basal regions of the incisor. One section in each pair was loaded until failure and a stress-strain curve for the periodontal ligament (PDL) was obtained. The other section was loaded to up to 50% of the maximum shear stress as determined from the contralateral section and then kept at a constant strain for 10 min, to obtain the stress-relaxation curve at the same region of the PDL. The maximum shear stress and toughness increased with age at the incisal region and the maximum shear strain increased with age at the incisal and middle regions. The tangent modulus decreased with advancing age at the middle region. The stress-relaxation during 10 min decreased with advancing age at the incisal and basal regions, but not at the middle region. The relaxation process was well described by a sum of three exponential decay functions, reflecting the short-, medium-, and long-term relaxation components. The age-related decrease in the relaxation was mainly attributable to increases in the ratio and relaxation time of the long-term relaxation component. These results suggest that with advancing age the mechanical strength and toughness of the PDL are enhanced mostly at the incisal region and that the viscous fraction is relatively decreased at the incisal and basal regions along the long axis of the rat incisor.

Closure of a Cervical H-Type Tracheoesophageal Fistula

Congenital H-type tracheoesophageal fistulae in adults are infrequent. In surgery, the essential components (defining, cutting, and suturing the fistula, and preventive interposition of muscle flap) must be performed precisely. We undertook these procedures through a small collar incision. Based on results of preoperative images, the fistula was identified under minimum dissection between the trachea and esophagus. After cutting and suturing the fistula, a sternohyoid muscle flap was interposed.