Shunichiro Nagahata

Changes in the expression of novel Cdk5 activator messenger RNA (p39nck5ai mRNA) during rat brain development.

We previously reported that a neuron-specific Cdk5 activator, p35nck5ai, was most prominent in the newborn rat brain. In the adult brain, the expression decreased in most regions except hippocampus and primary olfactory cortex. A novel neuron-specific Cdk5 activator, p39nck5ai, has been recently cloned. To clarify whether two activators were differentially distributed throughout brain development, in this study, we examined the spatial and temporal expression of p39nck5ai in the development rat brain. Northern blot analysis showed that p39nck5ai expression was low in 15-day old fetuses and newborn, and was most prominent in the 1-3 week-old rat brains. In the adult rat brain, expression declined to the same level as in newborn rat brain. In situ hybridization showed that p39nck5ai mRNA was weakly expressed in all neurons of all regions in the newborn rat brain and the transcriptional level was highest in all regions in the 3 week-old rat brain. In the adult, expression was decreased in most neurons except Purkinje and granule cells in the cerebellum which retained high levels. These results suggest that p35nck5a and p39nck5ai may have different functional roles in distinct brain regions during different states of the rat brain development.

Developmental alteration and neuron-specific expression of bone morphogenetic protein-6 (BMP-6) mRNA in rodent brain

Bone morphogenetic proteins (BMPs) are a group of proteins which induce bone formation from mesenchymal cells. The existence of BMPs in the nervous system as well as in bone tissue has recently been reported. In this study, we show that BMP-6 is neuron-specific, and describe the temporal and spatial expression patterns of BMP-6 mRNA in the developing rat and gerbil brain. Northern blot analysis showed that the BMP-6 transcript level was specifically high from newborn to 3 weeks after birth compared with those in fetal and adult rats. In situ hybridization showed that most of the neurons possessed high levels of BMP-6 mRNA in the neonatal brain, while in the adult brain, BMP-6 mRNA level was significantly decreased in most of the neurons except those in hippocampus which retained high levels. Furthermore, to show that the BMP-6 expression was specific to neurons, we induced delayed neuronal cell death and compensative glial cell proliferation in the gerbil hippocampus by transient ischemia. Our findings collectively suggest that BMP-6 is neuron-specific and may play important roles in neuronal maturation and synapse formation.

Florid cemento-osseous dysplasia. Report of a case.

A case of florid cemento-osseous dysplasia in a 16-year-old Japanese boy is presented. The lesion was unusually large and affected all four quadrants. Progressive increase in the bulk of the lesion was seen.

Cyclin-dependent kinase inhibitor p27 is related to cell proliferation and prognosis in laryngeal squamous cell carcinomas

An immunohistochemical study of both p27 and proliferating cell nuclear antigen (PCNA) was performed on 102 cases of laryngeal squamous cell carcinomas (LSCCs), and large variations in p27 expression were found among the tumours. Reduced expression of p27 was revealed in 54 (52.9 per cent) cases and correlated with tumour size, lymph node metastasis, and clinical stage, but did not correlate with age, sex, tumour site, or tumour grade. A significant positive correlation was found between the percentage of loss of p27 expression and the PCNA index (r = 0.844, p < 0.0001). Reduced expression of p27 was significantly correlated with both reducing disease-free and overall survival by univariate analysis. By multivariate analysis, reduced expression of p27, tumour grade, tumour size, lymph node metastasis as well as clinical stage were independent prognostic factors for overall survival of LSCCs. These findings indicate that reduced expression of p27 may be correlated with the malignant biological behaviour of LSCCs.

A long-term study of implanted artificial hydroxyapatite particles surrounding the carotid artery in adult dogs

In this long-term study, we implanted HAP into adult dogs using a silicone chamber attached to the carotid artery to clarify tissue reaction to HAP implantation over a long period. We designed chambers and both hemispheres of the chambers were filled with HAP particles, and were placed around both carotid arteries of seven adult dogs. The implants were removed after 150, 300, 380 days, and histological and ultrastructual examination was undertaken. We observed bone-like tissue which was formed where HAP particles were implanted. Immunohistochemical findings showed that osteocalcin and osteonectin were as positive in the bone-like tissue as in normal bone. This study suggests that biological factors from the arterial wall might play an important role in new bone-like tissue forming, and that HAP has a strong osteoconductive ability even at heterogeneous sites.

Overexpression of cyclin E and cyclin-dependent kinase 2 is correlated with development of hepatocellular carcinomas

Mammalian cell cycle progression is regulated by the combined action of cyclins/cyclin-dependent kinases (CDKs) and CDK inhibitors. Abnormal expression as well as interaction of these proteins may result in malignant transformation of cells. To further address the role of these cell cycle proteins in hepatocellular carcinomas, we analyzed the expression of cyclin E and CDK2. A panel of livers with human hepatocellular carcinoma, liver cirrhosis, and chronic hepatitis were used as a human experimental system. The inbred LEC (Long-Evans with a cinnamon-like coat color) rats were used as an animal experimental HCC model. Immunohistochemical staining of serial paraffin sections was performed using antibodies to cyclin E and CDK2. The results showed that cyclin E and CDK2 were concurrently overexpressed in hepatocellular carcinomas both in human and rat livers. Western blot analysis and CDK2 kinase assay demonstrated expression levels of cyclin E and CDK2 and CDK2 kinase activity, respectively, and both were shown to increase along with the development of hepatocellular carcinomas. Analysis of the correlation between expression of cyclin E and CDK2 and clinicopathological parameters revealed a significant correlation between expression of cyclin E and tumor grade (P=0.013), and PCNA index (P=0.006) as well as CDK2 expression (P=0.015). Overexpression of CDK2 tended to be associated with poorly differentiated HCCs. The results suggest that overexpression of cyclin E and CDK2 plays an important role in the development of hepatocellular carcinoma.

Distribution and morphology of valves in the human external jugular vein: Indications for utilization in microvascular anastomosis

PURPOSE This study examined the valves in the external jugular vein (EJV) that could affect microvascular anastomosis and increase the risk of thrombogenesis. MATERIALS AND METHODS The EJVs of 57 sides from 36 cadavers aged 40 to 95 years (20 males and 16 females) were dissected. After opening the veins, the distribution and morphology of the valves were investigated using a stereoscopic microscope. The length of the valves and inner diameter of the vessels were measured and related to the location of the valves. RESULTS Forty-nine (86%) of 57 EJVs were confluent with the subclavian vein. The EJV possessed bicuspid valves, and in 46 (93.9%) of the 49 specimens there were valves at the junction with the subclavian vein, whereas 44 (89.8%) contained valves in the middle portion of the specimen. The length of the valves was less than twice the inner diameter, and some were occasionally only rudimentary. CONCLUSION Numerous valves exist in the middle portion of the EJV where microvascular anastomoses are performed. When valves are observed in the site of anastomosis, they can be avoided by resecting a length equal to approximately twice the inner diameter.

Morphological study of the human maxillofacial venous vasculature: Examination of venous valves using the corrosion resin cast technique

The venous drainage in the human head and neck, structures located superior to the heart, generally does not counter the force of gravity. Accordingly, venous valves in the human head have been reported to be few or nonexistent, and therefore the direction of venous drainage is variable and obscure.

Anatomical study on values of human facial veins

The valves of the facial veins of 39 sides from 20 cadavers, aged 54-95 years, were investigated. Anatomical study of the valves is important, because the facial veins can be used for microvascular anastomosis in reconstruction in the head and neck. The present study confirmed that valves existed in the human facial veins, and were most frequently observed around the lower border of the mandible. When valves were classified into 5 types according to the morphology of the lobules, bicuspid valves were the most common (93.5%), followed by traced valves (4.1%), valve preparation (1.3%), and unicuspid valves (0.9%). However, no tricuspid valves were observed. Valves appeared most often (82.9%) at confluences with the facial veins. The length of valves in the trunk of the facial veins was twice the size of the inner diameter of the vessels in 78.4% of the cases. Therefore, when valves were observed at the anastomosis sites, the present results indicated that these valves could be avoided by resecting a length of about twice the inner diameter.

Rhabdomyosarcoma of the Mandible

Abstract This report is of an embryonal rhabdomyosarcoma presenting in the mandible of a 12-year-old boy. The tumour exhibited rapid growth and resistance to chemotherapy. The clinical findings, diagnostic course, and treatment are described in detail.