Developing long bones respond to surrounding tissues by trans-pairing of periosteal osteoclasts and endocortical osteoblasts.

Developing long bones alter their shape while maintaining uniform cortical thickness via coordinated activity of bone-forming osteoblasts and bone-resorbing osteoclasts at periosteal and endosteal surfaces, a process we designate trans-pairing. Two types of trans-pairing shift cortical bone in opposite orientations: peri-forming trans-pairing (peri-t-p) increases bone marrow space and endo-forming trans-pairing (endo-t-p) decreases it, via paired activity of bone resorption and formation across the cortex. Here, we focused on endo-t-p in growing bones. Analysis of endo-t-p activity in the cortex of mouse fibulae revealed osteoclasts under the periosteum compressed by muscles, and expression of RANKL in periosteal cells of the cambium layer. Furthermore, mature osteoblasts were localized on the endosteum, while preosteoblasts were at the periosteum and within cortical canals. X-ray tomographic microscopy revealed the presence of cortical canals more closely associated with endo- than with peri-t-p. Sciatic nerve transection followed by muscle atrophy and unloading induced circumferential endo-t-p with concomitant spread of cortical canals. Such canals likely supply the endosteum with preosteoblasts from the periosteum under endo-t-p, allowing bone shape to change in response to mechanical stress or nerve injury.

Ontogenic transformation of the ankle from the initial mediolateral arrangement of the calcaneus and talus: A histological study of human embryos and early fetuses.

The human calcaneus is robust and provides a prominent heel for effective bipedal locomotion, although the adjacent talus has no muscle attachments. However, there is incomplete information about the morphological changes in these prominent bones during embryo development. We examined serial histological sections of 23 human embryos and early-term fetuses (approximately 5-10 weeks' gestational age [GA]). At a GA of 5 weeks, the precartilage talus was parallel to and on the medial side of the calcaneus, which had a prolate spheroid shape and consisted of three masses. At a GA of 6 weeks, the cartilaginous talus extended along the proximodistal axis, and the tuber calcanei became long and bulky, with a small sustentaculum talus at the "distal" side. At a GA of 6 to 8 weeks, the sustentaculum had a medial extension below the talus so that the talus "rode over" the calcaneus. In contrast, the talus had a more complex shape, depending on the growth of adjacent bones. At a GA of 9 to 10 weeks, the talus was above the calcaneus, but the medial part still faced the plantar subcutaneous tissue because of the relatively small sustentaculum. Therefore, the final morphology appeared after an additional several weeks. Muscle activity seemed to facilitate growth of the tuber calcanei, but growth of the other parts of calcaneus, including the sustentaculum, seemed to depend on active proliferation at the different sites of cartilage. Multiple tendons and ligaments seemed to fix the talus so that it remained close to the calcaneus.

Generation of bicistronic Dmp1-Cre knock-in mice using a self-cleaving 2A peptide.

INTRODUCTION: The conditional manipulation of genes using the Cre recombinase-locus of crossover in P1 (Cre/loxP) system is an important tool for revealing gene functions and cell lineages in vivo. The outcome of this method is dependent on the performance of Cre-driver mouse strains. In most cases, Cre knock-in mice show better specificity than randomly inserted Cre transgenic mice. However, following knock-in, the expression of the original gene replaced by Cre is lost. MATERIALS AND METHODS: We generated a new differentiated osteoblast- and osteocyte-specific Cre knock-in mouse line that carries the viral T2A sequence encoding a 2A self-cleaving peptide at the end of the coding region of the dentin matrix protein 1 (Dmp1) gene accompanied by the Cre gene. RESULTS: We confirmed that Dmp1-T2A-Cre mice showed high Cre expression in osteoblasts, osteocytes, odontoblasts, and periodontal ligament cells and that the 2A self-cleaving peptide efficiently produced both Dmp1 and Cre proteins. Furthermore, unlike the Dmp1 knockout mice, homozygous Dmp1-T2A-Cre mice showed no skeletal abnormalities. Analysis using the Cre reporter strain confirmed differentiated osteoblast- and osteocyte-specific Cre-mediated recombination in the skeleton. Furthermore, recombination was also detected in some nuclei of skeletal muscle cells, spermatocytes, and intestinal cells. CONCLUSION: 2A-Cre functions effectively in vivo, and Dmp1-T2A-Cre knock-in mice are a useful tool for studying the functioning of various genes in hard tissues.

Effects of changes in end-tidal carbon dioxide tension on oral tissue blood flow and tissue oxygen tension during remifentanil infusion in rabbits.

PURPOSE: The aim of this study was to investigate the effects of end-tidal carbon dioxide tension (ETCO2) changes during remifentanil infusion on mandibular bone marrow tissue blood flow (BBF), masseter muscle tissue blood flow (MBF), mandibular bone marrow tissue oxygen tension (PbO2) and masseter muscle tissue oxygen tension (PmO2) in rabbits. METHODS: Ten male tracheotomized Japan White rabbits were anesthetized and ventilated with sevoflurane. ETCO2 was adjusted to 30 mmHg. After baseline measurement, CO2 was added to the inhaled air, and ETCO2 was increased to 40 and 60 mmHg. Heart rate (HR), systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial pressure (MAP), BBF, MBF, PbO2, and PmO2 were recorded with and without remifentanil infusion at 0.4 µg/kg/min. RESULTS: Two-way repeated measures analysis of variance showed no interaction between ETCO2 and remifentanil in all variables. Remifentanil infusion produced decreases in HR, SBP, MAP, BBF and MBF compared with those without remifentanil infusion, while it did not affect DBP, PbO2 and PmO2. Elevation of ETCO2 from 30 to 60 mmHg produced decreases in HR and MBF, and increases in SBP, DBP, MAP and BBF, while it did not affect PbO2 and PmO2. CONCLUSION: PbO2 and PmO2 remained unchanged despite changes in BBF and MBF during ETCO2 change with or without remifentanil infusion.

Tissue-nonspecific alkaline phosphatase promotes the osteogenic differentiation of osteoprogenitor cells.

Tissue-nonspecific alkaline phosphatase (TNAP) is expressed in the calcification sites of the skeletal tissue. It promotes hydroxyapatite crystal formation by degrading inorganic pyrophosphate (PPi) and increasing inorganic phosphate (Pi) concentration. However, abnormalities in Alpl-/- mouse-derived osteoblasts are poorly understood, and the involvement of TNAP in osteoblast differentiation remains unclear. Therefore, in this study, we aimed to investigate the precise role of TNAP in osteoblast differentiation. TNAP inhibition by levamisole, a reversible TNAP inhibitor, suppressed the expression of osteoblast differentiation marker genes in wild-type osteoblastic cells. Alpl overexpression increased the expression of master osteoblast transcription factor genes runt-related transcription factor 2 (Runx2) and Sp7 and the mature osteoblast and osteocyte marker genes, bone γ-carboxyglutamate protein 2 (Bglap2) and dentin matrix protein 1 (Dmp1), respectively in Alpl-deficient osteoblastic cells. TNAP regulated Runx2 expression, which in turn regulated the expression of all other osteoblast markers, except Dmp1. Dmp1 expression was independent of RUNX2 but was dependent on extracellular Pi concentration in Runx2-deficient osteogenic cells. These results suggest that TNAP functions as an osteogenic differentiation regulator either by regulating Runx2 expression or by controlling extracellular Pi concentration.

High-Level Expression of Alkaline Phosphatase by Adeno-Associated Virus Vector Ameliorates Pathological Bone Structure in a Hypophosphatasia Mouse Model.

Hypophosphatasia (HPP) is a systemic skeletal disease caused by mutations in the gene encoding tissue-nonspecific alkaline phosphatase (TNALP). We recently reported that survival of HPP model mice can be prolonged using an adeno-associated virus (AAV) vector expressing bone-targeted TNALP with deca-aspartate at the C terminus (TNALP-D10); however, abnormal bone structure and hypomineralization remained in the treated mice. Here, to develop a more effective and clinically applicable approach, we assessed whether transfection with TNALP-D10 expressing virus vector at a higher dose than previously used would ameliorate bone structure defects. We constructed a self-complementary AAV8 vector expressing TNALP driven by the chicken beta-actin (CBA) promoter (scAAV8-CB-TNALP-D10). The vector was injected into both quadriceps femoris muscles of newborn HPP mice at a dose of 4.5 × 1012 vector genome (v.g.)/body, resulting in 20 U/mL of serum ALP activity. The 4.5 × 1012 v.g./body-treated HPP mice grew normally and displayed improved bone structure at the knee joints in X-ray images. Micro-CT analysis showed normal trabecular bone structure and mineralization. The mechanical properties of the femur were also recovered. Histological analysis of the femurs demonstrated that ALP replacement levels were sufficient to promote normal, growth plate cartilage arrangement. These results suggest that AAV vector-mediated high-dose TNALP-D10 therapy is a promising option for improving the quality of life (QOL) of patients with the infantile form of HPP.

Decreases in Oral Tissue Blood Flow Induced by Remifentanil Are Not Accompanied by Deterioration of Oral Tissue Oxygen Tension in Rabbits.

PURPOSE: The purpose of this study was to investigate the effects of remifentanil infusion on tissue blood flow and tissue oxygen tension in the mandibular bone marrow and masseter muscle in rabbits. In addition, changes in tissue oxygen consumption in those tissues during remifentanil infusion were investigated. MATERIALS AND METHODS: Sixteen male tracheotomized Japanese White rabbits were anesthetized with sevoflurane under mechanical ventilation. Under oxygen and air inhalation, fraction of inspiratory oxygen was set at 0.4 and remifentanil was infused at a rate of 0.4 µg ∙ kg-1 ∙ min-1. Measurements were performed before remifentanil infusion, 20 minutes after the start of remifentanil infusion, and 20 and 60 minutes after the completion of remifentanil infusion (n = 8). The observed variables included heart rate (HR), systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial pressure (MAP), mandibular bone marrow tissue blood flow (BBF), masseter muscle tissue blood flow (MBF), mandibular bone marrow tissue oxygen tension (PbO2), and masseter muscle tissue oxygen tension (PmO2). Another 8 rabbits were observed for arterial pH, lactate, base excess (BE), and tissue oxygen consumption in the region from which the retromandibular vein received venous blood. Measurements were performed before remifentanil infusion and 20 minutes after the start of remifentanil infusion. RESULTS: HR, SBP, DBP, MAP, BBF, and MBF decreased during remifentanil infusion. PbO2 increased 20 minutes after remifentanil infusion and returned to almost the baseline value 60 minutes after remifentanil infusion. PmO2 did not change throughout the experiment. The difference between the arterial oxygen content of the femoral artery and the venous oxygen content of the retromandibular vein decreased during remifentanil infusion. Arterial pH, lactate, and BE did not change during remifentanil infusion. CONCLUSIONS: Remifentanil decreased BBF and MBF but did not decrease PbO2 and PmO2. It is suggested that tissue oxygen consumption decreased during remifentanil infusion.

Inhibition of the oxygen sensor PHD2 in the liver improves survival in lactic acidosis by activating the Cori cycle.

Loss of prolyl hydroxylase 2 (PHD2) activates the hypoxia-inducible factor-dependent hypoxic response, including anaerobic glycolysis, which causes large amounts of lactate to be released from cells into the circulation. We found that Phd2-null mouse embryonic fibroblasts (MEFs) produced more lactate than wild-type MEFs, as expected, whereas systemic inactivation of PHD2 in mice did not cause hyperlacticacidemia. This unexpected observation led us to hypothesize that the hypoxic response activated in the liver enhances the Cori cycle, a lactate-glucose carbon recycling system between muscle and liver, and thereby decreases circulating lactate. Consistent with this hypothesis, blood lactate levels measured after a treadmill or lactate tolerance test were significantly lower in Phd2-liver-specific knockout (Phd2-LKO) mice than in control mice. An in vivo (13)C-labeled lactate incorporation assay revealed that the livers of Phd2-LKO mice produce significantly more glucose derived from (13)C-labeled lactate than control mice, suggesting that blockade of PHD2 in the liver ameliorates lactic acidosis by activating gluconeogenesis from lactate. Phd2-LKO mice were resistant to lactic acidosis induced by injection of a lethal dose of lactate, displaying a significant elongation of survival. Moreover, oral administration of a PHD inhibitor improved survival in an endotoxin shock mice model. These data suggest that PHD2 is a potentially novel drug target for the treatment of lactic acidosis, which is a serious and often fatal complication observed in some critically ill patients.

Effect of Topical Anesthesia Using an Adhesive Patch and Anesthetic Solution.

We analyzed trigeminal somatosensory evoked potentials (TSEP) to the alveolar mucosa to investigate the efficacy of an amide local anesthetic, 2% lidocaine hydrochloride with 12.5 µg/mL epinephrine (Lido treatment) as a topical anesthetic. Eighteen consenting healthy adult volunteers were enrolled. A volume of 0.06 mL of Lido, 0.06 g of 20% benzocaine, or 0.06 mL of physiological saline (control) was instilled onto a hemostatic adhesive patch, which was then applied to the alveolar mucosa at the maxillary right canine for 5 minutes. An electrical stimulus approximately 5 times that of the sensory threshold was applied using a surface stimulation electrode. The trigeminal somatosensory evoked potential was recorded immediately, 5 minutes, and 10 minutes after removal of the patch. Positive P125 and P310 peaks and negative N100 and N340 peaks were observed as a result of the electrical stimulation. A significant decrease in the percentage change in amplitude of N100-P125 was observed in the Lido treatment immediately, 5 minutes, and 10 minutes after patch removal. In the Lido treatment, trigeminal somatosensory evoked potential amplitude at N100-P125 decreased significantly, suggesting that topical anesthesia produced by an amide local anesthetic may have a topical anesthetic effect as potent as that produced by an ester local anesthetic.

Effect of changes in end-tidal carbon dioxide tension on oral tissue blood flow during dexmedetomidine infusion in rabbits.

A decrease in arterial carbon dioxide tension induces an increase in masseter muscle blood flow and a decrease in mandibular bone marrow blood flow during general anesthesia. In addition, dexmedetomidine infusion reduces oral tissue blood flow. In this study we investigated how end-tidal carbon dioxide tension (ET-CO2 ) changes influence on oral tissue blood flow during continuous dexmedetomidine infusion in rabbits. Eleven male Japan White rabbits were anesthetized with sevoflurane. Then, ET-CO2 was set at 30 mmHg and adjusted to 40 and 60 mmHg, and heart rate, systolic blood pressure, diastolic blood pressure, mean arterial pressure, common carotid artery blood flow, mandibular bone marrow blood flow, masseter muscle blood flow, and blood flow in other oral tissues were measured. Following this, the ET-CO2 was returned to 30 mmHg and dexmedetomidine was infused over 60 min. The measurements were repeated. Most parameters increased, regardless of whether or not dexmedetomidine was present, and heart rate and masseter muscle blood flow decreased in an ET-CO2 -dependent manner. Dexmedetomidine infusion suppressed ET-CO2 -dependent masseter muscle blood flow change. Masseter muscle blood flow during ET-CO2 at 30 mmHg with dexmedetomidine was the same as that during ET-CO2 at 40 mmHg without dexmedetomidine. Our findings suggest that dexmedetomidine infusion and slight hypocapnia under general anesthesia suppress an increase in masseter muscle blood flow as well as reducing mandibular bone marrow blood flow. These results may be of significance for decreasing bleeding during oral and maxillofacial surgery.

Concomitant administration of nitrous oxide and remifentanil reduces oral tissue blood flow without decreasing blood pressure during sevoflurane anesthesia in rabbits.

PURPOSE: To determine whether continuous administration of nitrous oxide and remifentanil­either alone or together­alters blood flow in oral tissues during sevoflurane anesthesia. METHODS: Eight male tracheotomized Japanese white rabbits were anesthetized with sevoflurane under mechanical ventilation. Heart rate (HR), systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial pressure (MAP), common carotid arterial blood flow (CCBF), tongue mucosal blood flow (TMBF), mandibular bone marrow blood flow (BBF), masseter muscle blood flow (MBF), upper alveolar tissue blood flow (UBF), and lower alveolar tissue blood flow (LBF) were recorded in the absence of all test agents and after administration of the test agents (50 % nitrous oxide, 0.4 µg/kg/min remifentanil, and their combination) for 20 min. RESULTS: Nitrous oxide increased SBP, DBP, MAP, CCBF, BBF, MBF, UBF, and LBF relative to baseline values but did not affect HR or TMBF. Remifentanil decreased all hemodynamic variables except DBP. Combined administration of nitrous oxide and remifentanil recovered SBP, DBP, MAP, and CCBF to baseline levels, but HR and oral tissue blood flow remained lower than control values. CONCLUSIONS: Our findings suggest that concomitant administration of nitrous oxide and remifentanil reduces blood flow in oral tissues without decreasing blood pressure during sevoflurane anesthesia in rabbits.

Tissue Blood Flow During Remifentanil Infusion With Carbon Dioxide Loading.

The aim of this study was to investigate the effect of changes in end-tidal carbon dioxide tension (ETCO2) during remifentanil (Remi) infusion on oral tissue blood flow in rabbits. Eight male tracheotomized Japan White rabbits were anesthetized with sevoflurane under mechanical ventilation. The infusion rate of Remi was 0.4 µg/kg/min. Carbon dioxide was added to the inspired gas to change the inspired CO2 tension to prevent changes in the ventilating condition. Observed variables were systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial pressure (MAP), heart rate (HR), common carotid artery blood flow (CCBF), tongue mucosal blood flow (TBF), mandibular bone marrow tissue blood flow (BBF), masseter muscle tissue blood flow (MBF), upper alveolar tissue blood flow (UBF), and lower alveolar tissue blood flow (LBF). The CCBF, TBF, BBF, UBF, and LBF values were increased, while MBF was decreased, under hypercapnia, and vice versa. The BBF, UBF, and LBF values were increased, while the MBF value was decreased, under hypercapnia during Remi infusion, and vice versa. The BBF, MBF, UBF, and LBF values, but not the CCBF and TBF values, changed along with ETCO2 changes during Remi infusion.

Survey on choice of intravenous sedative agent at department of dental anesthesiology, Tokyo Dental College Chiba Hospital between 2010 and 2011.

Use of intravenous sedation is increasing in the management of dental patients in consideration of accompanying diseases and patient demand for comfort and safety. We surveyed choice of sedative agent and dosage on the basis of accompanying diseases or conditions in patients receiving treatment at the Department of Dental Anesthesiology, Tokyo Dental College Chiba Hospital between 2010 and 2011. A total of 5,256 patients were reviewed and divided into the following categories: 1) medically compromised patients (MC); 2) minor oral surgery (OS); 3) cerebral palsy (CP); 4) mental retardation (MR); 5) mental disorder (MD); and 6) dental phobia with/without gag reflex. The investigated variables were sex, age, weight, duration of sedation, and dosage of agent. Dosage of midazolam (M), M plus propofol (MP), and P alone was investigated. A total of 2,336 patients were managed by intravenous sedation during the study period. The combination of MP was used in approximately 63-79% of patients in all categories, except MC. Midazolam was used in approximately 47% in the MC group. Propofol was used in approximately 32% of patients in the MR group. Other agents (minor tranquilizers, analgesics, and so on) were used in approximately 12% in the OS group. The dose of M was approximately 0.05-0.06 mg/kg. When MP was administered, the dose of M showed no difference among groups. The dose of P, however, tended to be lower in the MC and CP groups than in the other groups. These results suggest that MP is chosen for intravenous sedation in most types of dental treatment.

Early changes in asporin levels in osteoarthritis of the temporomandibular joint.

OBJECTIVES: The present study aimed to elucidate the pathogenesis of temporomandibular joint (TMJ) osteoarthritis (TMJ-OA) in a mouse model. We investigated morphological and histological changes in the head of mandible cartilage and early immunohistochemical (IHC) changes in transforming growth factor (TGF)-ß, phosphorylated Smad-2/3 (p-Smad2/3), a TGF-ß signaling molecule, and asporin. METHODS: TMJ-OA was induced in a mouse model through unilateral partial discectomy. Micro-computed tomography (micro-CT) and safranin-O staining were performed to morphologically and histologically evaluate the degeneration of the head of mandible caused by TMJ-OA. IHC staining for TGF-ß, p-Smad2/3, and asporin was performed to evaluate the changes in protein expression. RESULTS: In the experimental group, three-dimensional (3D) morphometry revealed an enlarged head of mandible and safranin-O staining showed degeneration of cartilage tissue in the early stages of TMJ-OA compared to the control group. IHC staining revealed that TGF-ß, p-Smad2/3, and asporin expression increased in the head of mandible cartilage before the degeneration of cartilage tissue, and subsequently decreased for a short period. CONCLUSION: The findings suggested a negative feedback relationship between the expression of asporin and the TGF-ß/Smad transduction pathway, which may be involved in the degeneration of the head of mandible in the early stages of TMJ-OA. Asporin is a potential biomarker of the early stages of TMJ-OA, which ultimately leads to the irreversible degeneration of TMJ tissues.

Sclerostin modulates mineralization degree and stiffness profile in the fibrocartilaginous enthesis for mechanical tissue integrity.

Fibrocartilaginous entheses consist of tendons, unmineralized and mineralized fibrocartilage, and subchondral bone, each exhibiting varying stiffness. Here we examined the functional role of sclerostin, expressed in mature mineralized fibrochondrocytes. Following rapid mineralization of unmineralized fibrocartilage and concurrent replacement of epiphyseal hyaline cartilage by bone, unmineralized fibrocartilage reexpanded after a decline in alkaline phosphatase activity at the mineralization front. Sclerostin was co-expressed with osteocalcin at the base of mineralized fibrocartilage adjacent to subchondral bone. In Scx-deficient mice with less mechanical loading due to defects of the Achilles tendon, sclerostin+ fibrochondrocyte count significantly decreased in the defective enthesis where chondrocyte maturation was markedly impaired in both fibrocartilage and hyaline cartilage. Loss of the Sost gene, encoding sclerostin, elevated mineral density in mineralized zones of fibrocartilaginous entheses. Atomic force microscopy analysis revealed increased fibrocartilage stiffness. These lines of evidence suggest that sclerostin in mature mineralized fibrochondrocytes acts as a modulator for mechanical tissue integrity of fibrocartilaginous entheses.

Prenatal asfotase alfa-mediated enzyme replacement therapy restores delayed calcification in a severe infantile form of hypophosphatasia model mice.

Hypophosphatasia (HPP) is a congenital disorder caused by mutations in the tissue-nonspecific alkaline phosphatase (TNALP) gene. The pathogenesis of HPP varies, ranging from severe cases in which there is total absence of fetal bone calcification, which leads to stillbirth, to relatively mild cases in which the effects are confined to the teeth, such as early loss of the primary teeth. In recent years, the establishment of enzyme supplementation as a treatment method has prolonged survival in patients; however, this approach does not provide sufficient improvement for failed calcification. Furthermore, the effects of enzyme replacement therapy on the jawbone and periodontal tissues have not yet been studied in detail. Therefore, in this study, we investigated the therapeutic effects of enzyme replacement therapy on jawbone hypocalcification in mice. Recombinant TNALP was administered to mothers before birth and newborns immediately after birth, and the effect of treatment was evaluated at 20 days of age. The treated HPP mice had improved mandible (mandibular length and bone quality) and tooth quality (root length of mandibular first molar, formation of cementum), as well as improved periodontal tissue structure (structure of periodontal ligament). Furthermore, prenatal treatment had an additional therapeutic effect on the degree of mandible and enamel calcification. These results suggest that enzyme replacement therapy is effective for the treatment of HPP, specifically in the maxillofacial region (including the teeth and mandible), and that early initiation of treatment may have additional beneficial therapeutic effects.

Subset of the periodontal ligament expressed leptin receptor contributes to part of hard tissue-forming cells.

The lineage of periodontal ligament (PDL) stem cells contributes to alveolar bone (AB) and cementum formation, which are essential for tooth-jawbone attachment. Leptin receptor (LepR), a skeletal stem cell marker, is expressed in PDL; however, the stem cell capacity of LepR+ PDL cells remains unclear. We used a Cre/LoxP-based approach and detected LepR-cre-labeled cells in the perivascular around the root apex; their number increased with age. In the juvenile stage, LepR+ PDL cells differentiated into AB-embedded osteocytes rather than cementocytes, but their contribution to both increased with age. The frequency of LepR+ PDL cell-derived lineages in hard tissue was < 20% per total cells at 1-year-old. Similarly, LepR+ PDL cells differentiated into osteocytes following tooth extraction, but their frequency was < 9%. Additionally, both LepR+ and LepR- PDL cells demonstrated spheroid-forming capacity, which is an indicator of self-renewal. These results indicate that both LepR+ and LepR- PDL populations contributed to hard tissue formation. LepR- PDL cells increased the expression of LepR during spheroid formation, suggesting that the LepR- PDL cells may hierarchically sit upstream of LepR+ PDL cells. Collectively, the origin of hard tissue-forming cells in the PDL is heterogeneous, some of which express LepR.

Unilateral stellate ganglion block produces bidirectional changes in tissue oxygen tension of the mental nerve in rabbits.

PURPOSE: The purpose of this study was to investigate changes in the tissue oxygen tension (PO(2)) of the mental nerve bilaterally before and after unilateral stellate ganglion block (SGB). MATERIALS AND METHODS: Nine male Japan white rabbits were used. Anesthesia was maintained by a continuous infusion of propofol under mechanical ventilation with room air. For the SGB, the tip of a 26-gauge needle was placed on the left transverse process of the cervical vertebra; 0.2 mL of 1% lidocaine solution was injected. Data were recorded immediately before SGB and when the maximal change in PO(2) after SGB was observed. Observed variables were heart rate, blood pressure, common carotid arterial blood flow, tongue mucosal blood flow, left PO(2), and right PO(2). RESULTS: PO(2) showed maximal changes 7.9 ± 2.0 minutes after SGB. No changes were observed in heart rate and blood pressure after SGB. Common carotid arterial blood flow, tongue mucosal blood flow, and left PO(2) were increased by 106.4% ± 39.8%, 36.2% ± 35.2%, and 38.7% ± 19.8%, respectively, after SGB. In contrast, right PO(2) was decreased by 29.8% ± 7.4% after SGB. CONCLUSIONS: These results suggest that unilateral SGB produces bidirectional changes in the PO(2) of the mental nerve and that SGB decreases the PO(2) of the mental nerve on the contralateral side.

Effectively improved 3-dimensional structural stability of atelocollagen-gelatin sponge biomaterial by heat treatment.

Atelocollagen-gelatin (ACG) sponge was fabricated from atelocollagen and gelatin by lyophilization without introducing toxic substances. This study aimed to investigate the effects of heat treatment on the 3-dimensional structural stability of ACG sponge biomaterial. ACG sponge samples were fabricated and heat treated at 125oC for 12 h in the vacuum. The results revealed that heat treatment did not affect porosity, pore size and mechanical compressive strength. Heat-treated ACG sponge showed decreased absorbance and peak shift of amid I (C=O) stretches, slightly higher water uptake degree and significantly decreased in vitro degradation rate. Moreover, heat-treated ACG sponge maintained good 3-dimensional surface morphology and porous microstructure throughout 7 days, while non-heat-treated ACG sponge collapsed in less than 24 h. The human mesenchymal stromal cells (hMSCs) were shown to adhere and grow well on heat-treated ACG sponges. These results indicate that heat treatment is effective and safe to stabilize 3-dimensional ACG sponge biomaterial for tissue engineering.

A case of zoster sine herpete of the trigeminal nerve.

Varicella-zoster virus reactivation causes zoster (shingles), a syndrome characterized by severe pain and a vesicular rash. The present report details a case of varicella-zoster virus reactivation of the maxillary and mandibular division of the right trigeminal nerve without evidence of vesicular rash (zoster sine herpete). It is difficult to identify owing to no typical clinical signs such as vesicular eruption. Zoster sine herpete of the trigeminal nerve, in particular, is rarely reported. In this case, the diagnosis was based on clinical findings and was supported by the demonstration of an immunoglobulin G antibody. Zoster sine herpete of the trigeminal nerve, in particular, should be considered in patients with severe facial pain over specific dermatomes, if they do not demonstrate appreciable findings of traumatic neuropathy, tumor or herpes zoster.