A rare bilateral variation on the dorsum of the hand: extensor digitorum brevis manus and extensor medii proprius / 대한해부학회지

A 78-year-old male cadaver showed bilateral anomalous muscles on the dorsum of the hand. An extensor digitorum brevis manus was noted on the dorsum of the right hand. It originated from the distal end of the radius and the radiocarpal joint ligaments and inserted into the metacarpophalangeal joint of the third digit. On the dorsum of the left hand, an extensor digiti medii proprius was identified. It originated from the distal third of the ulna near the extensor indicis proprius and the interosseous membrane and inserted into the metacarpophalangeal joint of the third digit. Awareness of these combined muscular variation would be helpful in understanding the identification of digital extensors and in requiring careful consideration for the reconstruction surgery of the hand.

Neuregulin 1/ErbB4 signaling attenuates neuronal cell damage under oxygen-glucose deprivation in primary hippocampal neurons / 대한해부학회지

Effects of CoCl2 on multi-lineage differentiation of C3H/10T1/2 mesenchymal stem cells

Mesenchymal stem cells (MSCs) in the bone marrow and other somatic tissues reside in an environment with relative low oxygen tension. Cobalt chloride (CoCl2) can mimic hypoxic conditions through transcriptional changes of some genes including hypoxia-inducible factor-1alpha (HIF-1alpha) and vascular endothelial growth factor (VEGF). This study evaluated the potential role of CoCl2 preconditioning on multi-lineage differentiation of C3H/10T1/2, a murine MSC line to understand its possible molecular mechanisms in vitro. CoCl2 treatment of MSCs markedly increased HIF-1alpha and VEGF mRNA, and protein expression of HIF-1alpha. Temporary preconditioning of MSCs with CoCl2 induced up-regulation of osteogenic markers including alkaline phosphatase, osteocalcin, and type I collagen during osteogenic differentiation, followed by enhanced mineralization. CoCl2 also increased chondrogenic markers including aggrecan, sox9, and type II collagen, and promoted chondrocyte differentiation. CoCl2 suppressed the expression of adipogenic markers including PPARgamma, aP2, and C/EBPalpha, and inhibited adipogenesis. Temporary preconditioning with CoCl2 could affect the multi-lineage differentiation of MSCs.

Nitric Oxide-Induced Autophagy in MC3T3-E1 Cells is Associated with Cytoprotection via AMPK Activation

Nitric oxide (NO) is important in the regulation of bone remodeling, whereas high concentration of NO promotes cell death of osteoblast. However, it is not clear yet whether NO-induced autophagy is implicated in cell death or survival of osteoblast. The present study is aimed to examine the role of NO-induced autophagy in the MC3T3-E1 cells and their underlying molecular mechanism. The effect of sodium nitroprusside (SNP), an NO donor, on the cytotoxicity of the MC3T3-E1 cells was determined by MTT assay and expression of apoptosis or autophagy associated molecules was evaluated by western blot analysis. The morphological observation of autophagy and apoptosis by acridine orange stain and TUNEL assay were performed, respectively. Treatment of SNP decreased the cell viability of the MC3T3-E1 cells in dose- and time-dependent manner. SNP increased expression levels of p62, ATG7, Beclin-1 and LC3-II, as typical autophagic markers and augmented acidic autophagolysosomal vacuoles, detected by acridine orange staining. However, pretreatment with 3-methyladenine (3MA), the specific inhibitor for autophagy, decreased cell viability, whereas increased the cleavage of PARP and caspase-3 in the SNP-treated MC3T3-E1 cells. AMP-activated protein kinase (AMPK), a major autophagy regulatory kinase, was activated in SNP-treated MC3T3-E1 cells. In addition, pretreatment with compound C, an inhibitor of AMPK, decreased cell viability, whereas increased the number of apoptotic cells, cleaved PARP and caspase-3 levels compared to those of SNP-treated MC3T3-E1 cells. Taken together, it is speculated that NO-induced autophagy functions as a survival mechanism via AMPK activation against apoptosis in the MC3T3-E1 cells.

Extracellular Matrix Metalloproteinase Inducer is Regulated Developmentally and Functionally in the Rat Submandibular Gland

The salivary gland undergoes complex process of growth and differentiation of the branching morphogenesis of ductal system during the prenatal and early postnatal periods which are regulated by various elements in the extracellular matrix. Extracellular matrix metalloproteinase inducer (EMMPRIN) is a cell adhesion molecule. In the present study, localization and expression of EMMPRIN in development and effects of chorda-lingual denervation and cyclosporine A (CsA) treatment on the EMMPRIN expression were investigated. Immunohistochemistry, RT-PCR and Western blot were used to determine expression level. Immunohistochemistry revealed that EMMPRIN was localized specifically in the cytoplasm of ductal cells, not acini of the submandibular gland all the postnatal periods. At prenatal day 18, when the formation of ducts was not definite, no immunoreactivity was observed. Both Western blot and RT-PCR analyses revealed that EMMPRIN expression was maintained up to postnatal day 7, decreased after postnatal day 10. The EMMPRIN expression was upregulated by the surgical denervation of the chorda-lingual nerve in the gland as well as by the CsA treatment. The present study suggests that EMMPRIN is a crucial molecule for maintaining physiological functions of the salivary gland.

Gene Expression Profiling by Microarray during Tooth Development of Rats

Odontogenic cells express many genes spatiotemporally through complex and intricate processes during tooth formation. Therefore, investigating them during the tooth development has been an important subject for the better understanding of tooth morphogenesis. The present study was performed to identify the genetic profiles which are involved in the morphological changes during the different stages of rat tooth development using the Agilent Rat Oligonucleotide Microarrays. Morphologically, the maxillary 3rd molar germ at 10 days post-partum (dpp) was at the cap/bell stage. In contrast, the maxillary 2nd molar germ showed the root development stage. After microarray analysis, there were a considerable number of up- or down-regulated genes in the 3rd and the 2nd molar germ cells during tooth morphogenesis. Several differentially expressed genes for nerve supply were further studied. Among them, neuroligin 1 (Nlgn 1) was gradually downregulated during tooth development both at the transcription and the translation level. Also, Nlgn 1 was mostly localized in the dental sac, which is an important component yielding the nerve supply. This genetic profiling study proposed that many genes may be implicated in the biological processes for the dental hard tissue formation and, furthermore, may allow the identification of the key genes involved in the nerve supply to the dental sac.

Occlusal Surface Analysis of Mandibular Premolars in Koreans / 체질인류학회지

The aim of this study was to investigate the characteristics of mandibular premolars regarding size and morphology in Koreans. Moreover, comparisons of gender difference in mandibular premolars were examined to expand anatomical database in Koreans. Data was obtained from students in School of Dentistry, Chonnam National University, Gwangju, Korea. The total number of participants was 66 (33 men and 33 women) and dental casts were fabricated. A total of nine items was investigated using a digital measuring software. Five measurements were performed including intercuspal distance (ID), buccolingual diameter (BL), mesiodistal diameter (MD), total crown area, and each cusp area. One item as each cusp area ratio was calculated, and three items were observed including the number of lingual cusp, occlusal groove patterns, and mesiolingual developmental groove. Comparison measurements were analyzed using paired t-tests, independent t-tests and Pearson correlation tests. Average values in mandibular second premolars were larger than first premolars in most of measurements with a significance with the exception of mesiodistal diameter (p=0.223). Overall average values were significantly higher in male than in female except intercuspal distance (p=0.607) and lingual cusp area (p=0.070) in mandibular premolars. The presence of mesiolingual developmental grooves in the first premolars was 59.1% (male 51.5%, female 66.7%). The most common occlusal groove patterns of the second premolar were a Y pattern, followed in order by H and U patterns. These results provide valuable morphological characteristics of mandibular premolars in Koreans.

Effects of Bisphosphonate on the Expression of Matrix Enzymes during Endochondral Ossification / 체질인류학회지

Bisphosphonates have been reported to have chondroprotective activities in addition to its original functions. However, mechanisms for these just began to be elucidated. Under the hypothesis that bisphosphonates may regulate expression and activities of matrix enzymes during degradation of cartilage for bone formation, we administrated an alendronate (1 mg/kg) to newborn rats subcutaneously once a day for 4, 7, and 10 days. To identify the effects of alendronate on cartilage, thickness of cartilage layer was measured by histomorphometry on the proximal epiphysis of tibia. Immunofluorescence staining and RT-PCR were performed to investigate the expressions of matrix enzymes in both in vitro and in vivo. MTS assay revealed that at 10(-3) M in concentration, alendronate significantly reduced viability of chondrocytes. The mRNA expressions of MMP-1, MMP-9, EMMPRIN, and TIMP-3 in primary chondrocytes were decreased by the alendronate treatment. Interestingly, TIMP-1 mRNA expression was significantly increased, whereas a constitutive form, TIMP-2 was relatively unchanged by the treatment. The thickness of proliferating layer at postnatal day 7 was not significantly different, whereas thickness of hypertrophied layer was significantly thicker in the alendronate group than in the control (p<0.01). Immunofluorescence demonstrated that the expressions of MMP-9, TIMP-2 and -3 were reduced, whereas TIMP-1 expression was increased by the alendronate administration. These results suggest that the alendronate have chondroprotective properties by down-regulation of MMPs and up-regulation of TIMPs during endochondral ossification.

Variations in the Cusps of Mandibular Molars in Koreans / 체질인류학회지

This study aimed to investigate the cusp size and morphological characteristics of permanent mandibular molars in Koreans with reference to the hypoconulid, and to analyze the differences and correlations between both sexes as well as between first and second mandibular molars. We obtained data from dental casts of 110 adults (78 males and 32 females). Mesiodistal and buccolingual diameters of first and second mandibular molars, the area of five cusps (protoconid, metaconid, hypoconid, entoconid, and hypoconulid), as well as the total cusp area and occlusal table area were measured. Paired t-test was performed to analyze the morphological differences between first and second mandibular molars and the sex differences between both sexes using SPSS program. Crown diameters and cusp areas of mandibular first molars were larger than those of mandibular second molars in both sexes. The hypoconulid was the most variable in size and morphological pattern among the five cusps, and the first molars showed a higher incidence of hypoconulid than the second molars. Except for the entoconid area of the first molar (p=0.06) and the hypoconulid area of the second molar (p=0.24), all other mean values were larger in males than in females, demonstrating a significant sexual dimorphism. These data suggest that the teeth which develop late in ontogeny tend to be smaller in size and more variable in morphological characteristics.

CsA Affects the Rat Submandibular Glands via Regulating the CypA Expression

The effects of the an immunosuppressive drug cyclosporine A (CsA), on the salivary gland are largely unknown, even though clinical trials for the stimulation of salivation using CsA have been attempted. Cyclophilin A (CypA) is known to be a binding protein for CsA. CypA has cell proliferation and tissue matrix change activities. In our present study, the presence of CypA in the gland and effects of CsA on CypA expression were investigated by immunohistochemistry, immunoblotting and RT-PCR analyses. CypA was immunohistochemically detected in various kinds of ducts in the submandibular glands of Sprague Dawley rats. The CypA mRNA level was highest at postnatal day 1 and gradually decreased in a time-dependent manner up to adulthood. The expression of CypA increased after a 10 day subcutaneous administration of CsA in postnatal day 1 rats. Surgical sections of the chorda-lingual nerve with impaired salivation showed no changes in CypA expression. A cell proliferation assay using PCNA anti-serum showed increased cell division following CsA treatment. These results suggest that CsA and CypA may act on ductal cells to regulate saliva composition rather than salivation levels.

Expression of Deleted in Colorectal Cancer in the Rat Trigeminal Ganglia

The deleted in colorectal cancer (DCC) protein mediates attractant responses to netrin during axonogenesis. In the rat trigeminal ganglia (TG), axons must extend toward and grow into the trigeminal nerve to innervate target tissues such as dental pulp. Our present study aimed to investigate the expression of DCC in the TG. Four developmental timepoints were assessed in the experiments: postnatal days 0, 7 and 10 and adulthood. RT-PCR and western blotting revealed that the expression of DCC mRNA and protein does not significantly change throughout development. Immunohistochemistry demonstrated that DCC expression in the TG was detectable in the perikarya region of the ganglion cells during development. Nerve injury at 3 and 5 days after the mandibular nerve had been cut did not induce altered expression of DCC mRNA in the TG. Moreover, DCC-positive cell bodies also showed similar immunoreactive patterns after a nerve cut injury. The results of this study suggest that DCC constitutively participates in an axonogenesis attractant in ways other than expression regulation.

Differential Expression of Osteonectin in the Rat Developing Molars

Tooth development involves bud, cap, bell and hard tissue formation stages, each of which is tightly controlled by regulatory molecules. The aim of this study was to identify genes that are differentially expressed during dental hard tissue differentiation. Sprague-Dawley rats at postnatal days 3, 6 and 9 were used in the analysis. Differential display RT-PCR (DD-PCR) was used to screen differentially expressed genes between the 2nd (root formation stage, during mineralization) and 3rd (cap stage, before mineralization) molar germs at postnatal day 9. The DNA detected in the 2nd molar germs showed homology to osteonectin only (GenBank accession no. NM_012656.1). The level of osteonectin mRNA expression was much higher in the 2nd molar germs than in the 3rd molar germs and was found to increase in a time-dependent manner from the early bell stage to the root formation stage in the 2nd molar germs. The pattern of osteonectin protein expression was consistent with these RT-PCR results. Osteonectin protein was found by immunofluorescent analysis to localize in odontoblasts and preodontoblasts rather than the dentin matrix itself. Further studies are needed to validate the involvement of osteonectin in mineralization and root formation.

MMP-2 and MMP-9 are Differentially Involved in Molar Growth

Matrix metalloproteinases (MMPs) have been implicated in tissue development and re-modeling. Dynamic morphological changes of tooth germs reflect involvement of these enzymes during odontogenesis. The present study was performed to investigate expression and localization of MMP-2 and MMP-9, which have been known to have type IV collagenase activities, in rat tooth germs at different developmental stages. MMP-2 expression was increased gradually in the tooth germs from cap to crown staged germs at both transcription and translation levels. The localization of this molecule was detected in secretory ameloblasts and preameloblasts. The strong immunoreactivities were occasionally seen along the basement membrane between ameloblasts (or preameloblasts) and odontoblasts (preodontoblasts). However, weak reactivity was detected in odontoblasts and reduced enamel epithelium. The level of MMP-9 expression in the tooth germs was higher in cap stage than in crown staged germs at both transcription and translation levels. They were strongly expressed in both ameloblasts and odontoblasts. Even though reduced enamel epithelium after enamel formation and inner enamel epithelium at the cap stage exhibited weak reactivity, strong reactivity was detected in dental follicles and perifollicular tissues surrounding cap staged germs. These results suggested that MMP-2 may involve degradation of the basement membrane during hard tissue formation, whereas MMP-9 might be involved in remodeling of follicular tissues.