Keikichi Shimada

Localization ofN-cadherin in the normal and regenerating nerve fibers of the chicken peripheral nervous system

Abstract The localization of N -cadherin in the normal, and regenerating nerve fibers was investigated by immunocytochemistry in the chicken sciatic nerve. The normal unmyelinated fibees exhibited N -cadherin immunoreactivity on the plasma membranes of axons and Schwann cells where they were in contact with each other, while myelinated fibers displayed no immunoreactivity except at the mesaxon where Schwann cell plasma membranes were attached to each other. In the regenerating nerves, intense immunoreactivity was demonstrated on the surface of plasma membranes of axons and Schwann cells where axon-axon and axon-Schwann cell contacts were made. No immunoreactivity was observed on the plasma membranes where regenerating axons or Schwann cells were in touch with the basal lamina. In addition, it was revealed that some vesicles in the growth cones had distinct N -cadherin immunoreactivity at the inner limiting membrane surface. These findings indicate that N -cadherin may be involved in the axon-axon and axon-Schwann cell adhesion in the normal unmyelinated as well as regenerating nerve fibers, and also in the attachment of Schwann cell processes at the mesaxon of myelinated fibers. In addition, these findings suggest that N -cadherin might be, at least in part, supplied by fusion of growth cone vesicles with the surface plasma membranes in growing axons.

GABAergic neurotransmission in rat taste buds: immunocytochemical study for GABA and GABA transporter subtypes.

Gamma-aminobutyric acid (GABA) is known to be a candidate for the neurotransmitter involved in the sense of taste. We hereby studied GABA and its termination system, GABA transporters, in rat taste buds by immunocytochemical approaches. Immunoblot analysis of three GABA transporter subtypes (GAT1, GAT2 and GAT3) revealed that the immunoreactive bands of GAT2 and GAT3, but not GAT1, were detected in the tongue. GAT3-immunoreactive band was recognized only in the circumvallate papilla containing a large number of taste buds while GAT2-immunoreactive bands were seen in all areas of the tongue. GAT2 immunoreactivity appeared to be specifically in the nerve fibers beneath the lingual epithelium. Both GAT3 and GABA immunoreactivities were detected only in taste buds. A few GAT3-immunoreactive cells were found in a cross-section of each taste bud but most GAT3-immunoreactive cells were localized in the margin of the taste bud. GAT3 was predominantly concentrated in the distal portion of the GAT3-immunoreactive cells. In contrast, GABA-immunoreactive cells were seen more frequently within each taste bud and the immunoreactivity was distributed throughout the perikarya of the cells. These results suggest that the GABA-uptake system is present in the taste buds and the GABAergic neurotransmission involved in the sensation of taste is terminated by the uptake of GABA into certain taste cells via GAT3.

Heterogeneity of primary malignant melanomas in oral mucosa: An analysis of 43 cases in Japan

&NA; In contrast to Caucasians, Japanese people have a relatively high incidence of malignant melanoma in the oral cavity and volarsubungual skin. The classification of oral melanoma has not been established. We report 7 new cases of oral melanoma, with a review of 36 cases, published in Japan, between 1970 and 1984. Most of the cases reviewed have radial growth phases, and their gross and microscopic features seem to correspond to those of acral lentiginous melanoma of the skin. However, 1 of our cases and 3 previously reported cases of oral nodular melanoma suggest the presence of melanoma heterogeneity in the oral cavity.

Immunocytochemical localization of serotonin and serotonin transporter (SET) in taste buds of rat

We used an immunocytochemical approach to study the localization of serotonin and its termination system, serotonin transporter (SET), in the taste buds of rats using specific antibodies against serotonin and SET. Under confocal laser scanning microscopy, both serotonin and SET immunoreactivity were detected in the taste buds of rat vallate papillae. Serotonin immunoreactivity was seen in the spindle-shaped cells with apical processes that seemed to be light (Type II) taste cells. SET-immunoreactivity was mainly localized in the periphery or interfaces between the taste cells. Double staining studies revealed that all serotonin-containing taste cells were immunoreactive for SET, while a subclass of SET-positive cells showed serotonin immunoreactivity. These data support the hypothesis that serotonin plays a transmitter role in taste receptor cells and suggest that the serotonin-induced sensation of taste is terminated by serotonin uptake through serotonin transporter.

Criteria for diagnosing lymph node metastasis from squamous cell carcinoma of the oral cavity: A study of the relationship between computed tomographic and histologic findings and outcome

PURPOSE This retrospective study was conducted to determine the relationship between the computed tomographic findings for cervical lymph nodes (LN), histologic findings, and outcome in patients with squamous cell carcinoma of the oral cavity who underwent radical neck dissection. PATIENTS AND MATERIALS Sixty-six patients were analyzed. Of these 66 operations, 43 were immediate therapeutic dissections in clinically N+ necks, and 23 were subsequent therapeutic dissections in patients whose necks were initially node free but progressed to positive nodes during observation. RESULTS When the size criterion (area of the axial section) of nodal metastasis depicted on the scan of 45 mm2 was selected, almost 78% of LN were diagnosed consistent with the histologic diagnosis. As the size of the LN increased, the frequency of extranodal invasion also became higher, whereas patients with the higher histologic grades of malignancy often showed neck metastases with extranodal invasion in the early stage. Patients having LN smaller than 100 mm2, or without extranodal invasion, showed good outcome, whereas those having LN 100 mm2 or larger, with extranodal invasion, showed extremely poor outcome. CONCLUSIONS These findings indicate that it is possible to delay neck dissection in node-free patients until neck disease is diagnosed with timely CT examination, although great caution is necessary, especially in those with a high histologic grade of malignancy.

Alpha N-catenin expression in the normal and regenerating chick sciatic nerve.

SummaryThe Ca2+-dependent intercellular adhesion molecule cadherin is known to be linked to the cytoskeleton by the protein catenin, an association of which appears to be important for the cell-adhesion function of cadherin. Catenin consists of three subtypes-α, β, and γ. In our previous study, N-cadherin was shown to be localized on the plasmalemma of normal and regenerating chick peripheral nerve. Thus, as αN-catenin is a subtype of α-catenin (which is specifically associated with N-cadherin), we investigated the immunolocalization of αN-catenin in normal and regenerating chick sciatic nerve. In normal nerve, unmyelinated axons exhibited either intense or weak αN-catenin immunoreactivity throughout the axoplasm, whereas myelinated axons were completely immunonegative. Regenerating axons, including those derived from parent myelinated axons, showed αN-catenin immunoreactivity of variable intensities in growth cones and axon shafts. Schwann cells were invariably devoid of immunoreactivity. Thus αN-catenin is not necessarily bound to the surface plasmalemma, but is distributed throughout the cytoplasm, suggesting that most αN-catenin molecules are dissociated from N-cadherin.

Molecular characterization of a novel cancer cell line established from human carcinoma in pleomorphic adenoma (CaPA-4).

A cultured cell line (CaPA‐4), derived from an undifferentiated carcinoma in a pleomorphic adenoma of the submandibular gland, was established through xenografted tumors in nude mice. Geneticin treatment eliminated surrounding mouse fibroblasts and yielded enriched tumor cells at an early stage of cell passage. In vitro, the line grew in a cobblestone pattern, revealing its epithelial origin. Chromosomal analysis by Giemsa‐banding confirmed its human origin, while electron microscopic examination showed its squamous‐cell characteristics. CaPA‐4 cells stained positive for the c‐myc and Ha‐ras antibodies. Molecular analysis showed over‐expression of both c‐myc and Ha‐ras mRNA, with point mutation of p53 at codon 248 and of Ha‐ras at codon 61. Amplification and rearrangement of the Ha‐ras gene were observed; however, no loss of heterozygosity (LOH) of the p53 gene was detected by Southern blotting. This sequence of cancer‐related gene activation may represent the malignant transformation from benign pleomorphic adenoma. This report describes the establishment and molecular characterization of this novel cell line from carcinoma in pleomorphic adenoma exhibiting squamous‐cell differentiation. This could represent a useful model for investigating the cause of malignant transformation from human salivary‐gland mixed tumors.

A clinical study of local recurrence after surgery in patients with squamous cell carcinoma of the oral mucosa.

1990年～1991年の口腔粘膜扁平上皮癌手術症例のうち, 原発巣再発をきたした22例について臨床的に検討し, 以下の結果を得た。1.舌癌22例中原発巣再発は9例に認められた。再発は局所進展例で舌半側切除, 亜全摘, 全摘を施行した症例に多かった。2.下顎歯肉癌の原発巣再発は42例中7例に認められた。再発はT4の局所進展例だけではなくT1・T2で口内法による下顎骨辺縁切除を施行した症例にも生じた。また, X線所見や組織学的悪性度と再発との関連性は認められなかった。3.口底癌の原発巣再発は17例中4例に認められた。再発はT2・T3で下顎骨辺縁切除を施行した症例に生じた。組織学的悪性度と再発との関連性は認められなかった。4.上顎歯肉癌の原発巣再発は22例中2例に認められた。再発はT1～T3の症例にはみられなかった。5.再発例22例のうち予後良好は7例のみで, 5年累積生存率は34.1%であった。

A case of histiocytic medullary reticulosis complicated with x-ray-irradiated oral cancer

We report the case of a patient in whom oral squamous cell carcinoma and a fatal reactive form of histiocytosis were simultaneously manifested. Our conclusions indicate that such a hematophagocytic syndrome may occur in the setting of oral squamous cell carcinoma as previously described in other malignancies.

Inhibitory Effect of Low Power Laser Irradiation on Neurite Elongation from Dorsal Root Ganglion (DRG)

We applied low power laser irradiation on cultured dorsal root ganglion (DRG) which was excised from mouse. Continous wave Ca-Al-As diode laser of 830 nm wave length and 20 mW power output was irradiated for 5-15 minutes. Neurite elongation from DRG was inhibited significantly by laserirradiation. It also inhibited neurite elongation of single neuron isolated from DRG. Especially that of small diameter neuron was significantly inhibited. By immunostaining. neurites including substance P and/or CGRP were shown to be affected severely. These results suggest that inhibitory effect of laser irradiation on neurite elongation may relate to the mechanism of pain attenuation. 緒言 低出力レーザー照射による除痛効果は近年、 医科歯科の臨床において広く応用されつつある が、その作用機序については不明な点が多い。 先に我々はXenopusの 培養三叉神経節を用いて、 神経線維の伸長が低出力レーザーの照射によっ て有意 に抑制 される事実 を発見 した(1)。 そこで 今回の研究では、哺乳類 においても同様の現象 が起 こるかを確かめ るために、マウス培養知覚 神経節(dorsal root ganglion,以 下DRG)を 用 いて、低出カ レーザ ー照射による神経線維の 伸 長への影響について検討 した。