Biomedical subjects

T Maeda

Publications and source records attributed to T Maeda.

At least 559 records · Page 31Linked to original sources

PubMed1996

Three-dimensional arrangement of enamel prisms and their relation to the formation of Hunter-Schreger bands in dog tooth.

The three-dimensional architecture of enamel prisms and their relationship to Hunter-Schreger bands were examined in the developing enamel of several dog teeth by light and electron microscopy, and computer-assisted reconstruction. Sections were prepared from a single demineralized tooth germ. Longitudinal semithin sections parallel to the meridian of the tooth showed parazones and diazones of the Hunter-Schreger bands in alternate rows at equal intervals. On sections vertical to the tooth crown through the middle region of parazone or diazone, a row of parallel prisms were angulated with the largest tilting angle being 55 degrees to the enamel-dentin junction, running in opposite directions in the respective zones. Tangential sections parallel to the enamel-dentin junction showed numerous belt-like zones arranged perpendicular to the meridian of the tooth. Each belt-like zone consisted of a group of enamel prisms oriented in the same direction, those in the neighboring zones being oriented in an opposite direction. The densely stained boundaries between the adjacent belt-like zones corresponded to the interface between parazone and diazone. Computer-reconstructed enamel prisms in the adjacent two zones were oriented in the opposite sidewards direction with occasional confluence and divergence. Scanning electron-microscopic observation of the developing enamel surface exposed by dissolution of the enamel organ revealed band-like arrangements of groups of pits encasing the Tomes' processes of secretory ameloblasts. The secretory faces of the pits inclined uniformly in the same sidewards direction, with those in the neighboring groups, in the opposite direction.

Animals↗

PubMed1996

Change in subcellular localization of gastrin-like immunoreactivity in epithelial cells of rat duodenum induced by carbachol.

The present study provides morphological evidence to support the contention of exocrine secretion from duodenal gastrin-containing cells. The isolated vascularly perfused duodenal preparation with or without carbachol stimulation was used. At the end of perfusion, tissue was fixed and prepared for electron microscopic examination. For immunoelectron microscopic study for gastrin, postembedding immunogold reaction combined with preembedding DAB staining was used. In saline-treated controls, DAB reaction was restricted to the basal cytoplasm and immunogold labeling was concentrated over electron-dense cores of secretory granules packed at the basal cytoplasm. However, in carbachol-stimulated animals, immunogold labeling as well as DAB reactions were accumulated at the apical portion of the cytoplasm, suggesting that a high concentration of gastrin was involved in the apical cytoplasm. In carbachol-stimulated cells, aggregation of small vesicles was observed beneath the microvilli, and most of these vesicles had no cores but were similar in size to the basal secretory granules. Immunogold particles were diffusely scattered at the cytoplasm outside these vesicles. These findings suggest that the gastrin-like immunoreactivity was pooled at the matrix of apical cytoplasm in carbachol-stimulated cells, which might be derived from the secretory granules migrated from the basal cytoplasm into apical portion of the cells. In conclusion, the present study demonstrated the change in subcellular localization of gastrin-like immunoreactivity in intestinal gastrin cells after stimulation with carbachol. Aggregation of immunoreactivity at the apical portion of the cells suggests that gastrin may be released into the intestinal lumen.

Animals↗

PubMed1996

Morphologic analysis of rat retino-collicular neuron terminals containing monoamine oxidase.

The retino-collicular neuron terminals containing type A monoamine oxidase (MAO-A) in the stratum griseum superficiale of the rat superior colliculus were analyzed to provide a morphologic basis for the physiologic role of these neurons in the visual pathway. A computer-assisted, three-dimensional reconstruction of the terminal complex associated with the MAO-A-positive terminals was performed. MAO-A-positive terminals originated in the retina and terminated in the stratum griseum superficiale. This was confirmed by tract tracing and enucleation experiments. The terminals were densely grouped in clusters of irregularly shaped swellings. Electron microscopy revealed that the MAO-A-positive terminals were located in a glomerulus-like structure. In this terminal complex, a significant proportion of the axonal profiles (42.96%) synapsed with the MAO-A-positive terminals. Most of the profiles (24.16%) resembled presynaptic dendrites, which represent intermediate elements between the retinal terminals and conventional dendrites. Unlike the glomerulus in the dorsal lateral geniculate body, the MAO-A-positive terminal swellings were not located in the central part of the terminal complex. The terminals had an irregular shape and were located in the complex. The terminal complex was partially ensheathed by glial processes. Furthermore, the membrane surfaces exhibiting synaptic specializations were very small compared with the total surface of the terminal swellings. The membrane length of the synaptic specialization was 5.38% of the total perimeter of the MAO-A-positive terminals.

Animals↗

PubMed1996

The distribution of noradrenaline, serotonin and gamma-aminobutyric acid in the monkey nucleus accumbens.

1. The recent histochemical studies have shown that the primate nucleus accumbens (NAC) can be subdivided into at least three subdivisions, the medial, ventral and dorsolateral subdivisions. 2. The medical subdivision possesses dense peptide- and dopamine-immunoreactive (IR) fibers. 3. In order to further investigate the neurochemical characteristics of the primate NAC, the distribution of structures that contain noradrenaline (NA), serotonin (5-HT) and gamma-aminobutyric acid (GABA) were examined in the macaque monkey by using transmitter-immunohistochemical methods. 4. Many NA-IR fibers were observed in the dorsal part of the NAC, corresponding to the medial subdivision. Fine varicose 5-HT-IR fibers were evenly distributed in the NAC. GABA-IR cell bodies and puncta were observed throughout the NAC as well as in the caudate nucleus and putamen. 5. The monkey rostral NAC displays a highly homogeneous distribution of all neuropeptides and neurotransmitters studied so far and we propose that this region be termed the rostral subdivision of the NAC.

Animals↗

PubMed1996

Effects of transfection with the Cu, Zn-superoxide dismutase gene on xanthine/xanthine oxidase-induced cytotoxicity in fibroblasts from rat skin.

PURPOSE: The effects of transfection with the human Cu, Zn-superoxide dismutase (hSOD)4 gene on active oxygen-induced cytotoxicity in rat skin fibroblasts (FR) were studied for the purpose of developing the novel delivery system of hSOD using hSOD gene. METHODS: An expression plasmid for hSOD, pRc/RSV-SOD, was constructed and used to transfect FR cells. Xanthine (X)/xanthine oxidase (XO) system were used to generate active oxygen species. The effects of transfection with the hSOD gene on active oxygen-induced cytotoxicity were assessed by comparing the number of surviving cells and the level of lipid peroxidation in host and transformants after exposure to X/XO system. RESULTS: The cellular SOD activity in RSV-SOD cells transfected with pRc/RSV-SOD was significantly increased in comparison with host or RSV cells transfected with the pRc/RSV plasmid containing no hSOD gene as a control. Furthermore, Western blot analysis using an anti-hSOD antibody indicated the production of hSOD in RSV-SOD cells. On the other hand, although the numbers of surviving cells in both host and RSV-SOD cultures after exposure to X/XO system decreased in a time-dependent manner, the decrease in number of surviving RSV-SOD cells was less than that in host cells. In the presence of catalase, the decreases in number of surviving cells in both host and RSV-SOD cultures after exposure to the X/XO system were also less than those in the absence of catalase. However, the decreases in cell survival in RSV-SOD cultures were significantly less than those in host cells in the presence of catalase. Furthermore, the levels of lipid peroxidation in RSV-SOD cells exposed to the X/XO system in the presence or absence of catalase were lower than those in host cells. These results indicated that the increase in cellular SOD activity by transfection with the hSOD gene protects cells from oxidative stress. CONCLUSIONS: Human SOD gene therapy may be useful for treatment of diseases in which oxidative tissue damage is produced.

Analysis of Variance↗

PubMed1996

Increased expression of a brain/embryo-type myosin heavy chain isoform (MIIB2) in mesangial proliferative glomerulonephritis.

Proliferation of mesangial cells is frequently found in glomerulonephritis, such as IgA glomerulonephritis. Recent reports suggest that a brain/embryo-type myosin isoform (MIIB2) is involved in cell proliferation. We have studied the expression of MIIB2 in renal biopsy samples from patients with various renal diseases and in the renal tissues from the rat model of mesangial proliferative glomerulonephritis induced with anti-Thy 1.1 antibody. Immunohistochemical analysis of the biopsy samples using an anti-brain-type myosin heavy chain-specific monoclonal antibody (HBM1) indicated that 92% of the samples from patients with IgA glomerulonephritis contained a significant population of mesangial cells that reacted with the antibody. Most of the samples from patients with other types of proliferative glomerular diseases also contained HBM1-reactive mesangial cells, while none of the samples from patients with non-proliferative glomerular diseases contained a significant population of HBM1-reactive mesangial cells. The expression of a brain/embryo-type myosin heavy chain isoform (MIIB2) in the mesangial cells began at five days after injection of anti-Thy 1.1 antibody and peaked at the tenth day. On the other hand, the expression of the proliferating cell nuclear antigen in the mesangial cells was induced at two days after injection of anti-Thy 1.1 antibody and was maximal at the fourth day. These results indicate that the expression of the MIIB2 isoform by mesangial cells is accelerated in proliferative glomerulonephritis and suggest that the myosin isoform is involved in the phenotypic transformations of the glomerular tissues rather than in the cell proliferation.

Adolescent↗

PubMed1996

Prognosis of recurrent hepatocellular carcinoma: a 10-year surgical experience in Japan.

BACKGROUND & AIMS: Little has been addressed on the characteristics and prognostic factors of recurrent hepatocellular carcinoma after undergoing a hepatic resection for primary hepatocellular carcinoma. The aim of this study was to clarify the aforementioned matters of recurrent hepatocellular carcinoma. METHODS: One hundred fifty-nine patients with recurrent hepatocellular carcinoma were studied retrospectively. Twenty-four clinicopathologic variables, including the period until recurrence (less than or more than 1 year), types of recurrence (intrahepatic nodular type, intrahepatic multiple type, and extrahepatic type), and types of treatment after recurrence (no treatment, lipiodolization, ethanol injection, or hepatectomy) were univariately and multivariately analyzed. RESULTS: The following three variables were finally selected as independent and prognostic indicators after recurrence: (1) period until recurrence, (2) type of recurrence, and (3) types of treatment after recurrence. CONCLUSIONS: The prognostic factors in patients with recurrent hepatocellular carcinoma were as follows: (1) period until recurrence, (2) types of recurrence, and (3) types of treatments received after recurrence. The establishment of a follow-up system, including an examination for extrahepatic recurrence, and the development of an effective method of adjuvant chemotherapy are required to obtain better treatment results.

Aged↗

PubMed1996

The role of GM1-ganglioside in the injured spinal cord of rats: an immunohistochemical study using GM1-antisera.

The effect of GM1-ganglioside (GM1) administration was investigated in the injured spinal cord of rats. Immunohistochemistry using GM1-antisera was applied in the study of GM1 distribution, and locomotor recovery was also evaluated. A total of 86 rats, subdivided into four groups, were used in the study. The SI + GM1 group (n = 30) underwent a thoracic cord injury, and then received daily intraperitoneal injections of GM1 (10 mg/kg) from 0 to 13 days after injury. The SI group (n = 30) also underwent thoracic cord injury, but did not receive GM1 treatment. The GM1 group (n = 20) received daily injections of GM1 in the absence of any spinal cord injury. The control group (n = 6) neither underwent spinal cord injury nor received GM1 treatment. The animals were sacrificed at 1, 3, 5, 7, and 14 days after injury for immunohistochemical evaluation. GM1 immunoreactive axons, myelin sheaths, and glial cells were counted in 5 light microscopic fields of spinal white matter. Immunohistochemical studies of the spinal cord revealed that GM1 treatment significantly increased both GM1-positive axons and GM1-positive myelin sheaths in the lateral funiculus surrounding the lesion site. The exogenous GM1 was incorporated predominantly into the myelin sheath rather than the axon. This distribution was detectable by day 1 of injury and persisted until day 14, and was significantly different from that of the control group on days 1 and 7. Moreover, GM1 treatment significantly accelerated the recovery of motor function. Collectively, these results suggest that exogenous GM1 administration after a spinal cord injury results in the rapid transfer of GM1 to the lateral funiculus where the motor transmission pathway is located. Furthermore, exogenous GM1 was shown to be specifically incorporated into the myelin sheath. Thus GM1 treatment may prevent demyelination and may contribute to motor function recovery.

Animals↗

PubMed1996

Evaluation of endometriosis in uterosacral ligaments by transrectal ultrasonography.

Uterosacral ligaments are one of the common targets of pelvic endometriosis, which is usually clinically rather than surgically diagnosed. This study was performed to determine if uterosacral ligaments infiltrated by endometriosis could be detected by transrectal ultrasonography. Uterosacral ligaments in non-endometriosis subjects (n = 64) were observed as low echoic homogeneous arcs in both sides of the uterine cervix. Patients who had endometriosis (n = 29) on the ligaments showed thick and irregularly-shaped uterosacral ligaments by the transrectal ultrasound examination. The results also suggested that the thickness of uterosacral ligaments was associated with the clinical symptoms. Transrectal ultrasonography may provide quantitative information to manage patients with infiltrating endometriosis.

Adult↗

PubMed1996

Structure determination of an immunopotentiator peptide, cinnamycin, complexed with lysophosphatidylethanolamine by 1H-NMR1.

The three-dimensional structure of a complex of cinnamycin, a 19-amino acid residue immunopotentiator peptide, and lysophosphatidylethanolamine was determined by 1H-NMR. The complex was cylindrical in shape, 11 A in diameter and 26 A in length, excluding the acyl chain of the phospholipid. The peptide had a hydrophobic pocket surrounded by residues Phe-7 through Ala(S)-14 to bind to the head group of the ligand. Fitting of the head group to the hydrophobic pocket was so good that other than a glycerophosphoethanolamine head group would be unable to fit the pocket. The goodness of the fitting is compatible with the strict specificity of ligand binding of the peptide.

Amino Acid Sequence↗

PubMed1996

Treatment with a novel lipid A analogue, FS-112, and partial hepatectomy causes submassive liver necrosis and impaired liver regeneration in mice.

A novel experimental model of submassive liver necrosis with impaired regeneration has been established. A novel lipid A analogue, FS-112, was injected intravenously into male BALB/c mice, followed 2 days later by a 70% partial hepatectomy. Over the next 9 days, mice became severely jaundiced, with a peak total bilirubin (TBil) concentration of (mean +/- s.d.) 12.9 +/- 2.1 mg/dL 7 days postoperatively. In contrast, the TBil concentration in vehicle-treated mice remained less than 2 mg/dL. Significant elevations of L-alanine:2-oxoglutarate aminotransferase (ALT) were also observed 3-7 days after the operation in mice pretreated with FS-112, compared with mice pretreated with the vehicle. Submassive liver necrosis was observed with extensive mononuclear cell infiltration in mice treated with FS-112 and subjected to partial hepatectomy. Furthermore, both the BrdU and the proliferating cell nuclear antigen (PCNA) labelling index (LI) 1 day following partial hepatectomy in mice pretreated with FS-112 (8.6 +/- 4.3 and 7.9 +/- 4.2%, respectively) were significantly lower than levels in vehicle-treated mice (25.8 +/- 3.8 and 26.5 +/- 10.5%, respectively). The time course of changes in the BrdU LI in liver specimens from mice treated with both FS-112 and partial hepatectomy did not increase, even 3, 5, and 7 days postoperatively. Excellent liver regeneration with a PCNA LI 10-fold higher than the resting level was observed in mice treated with D-galactosamine hydrochloride. These results strongly suggest that this animal model of submassive liver necrosis may be suitable for clarifying the mechanisms of impaired liver cell regeneration often seen in fulminant hepatitis.

Animals↗

PubMed1996

Proliferative activity in intrahepatic metastasis of hepatocellular carcinoma.

To assess the characteristics of intrahepatic metastatic lesions (IML) in hepatocellular carcinoma (HCC), we analysed both the histological features and proliferative activities of 15 resected cases of HCC accompanied by IML. The histological features of the IML were essentially the same as those observed in the main nodules in 12 (80%) of 15 cases. In 13 (87%) of 15 cases, the labelling index of proliferating cell nuclear antigen (PCNA) in the IML was either higher than or the same as in the main nodules. In 10 (77%) of 13 cases, the MIB-1 labelling index in the IML was either higher than or the same as in the main nodules. The results indicate that the histological features of the IML are essentially the same as those of the main nodules, while the proliferative activities in the IML were generally higher than those in the main nodules. Such characteristics may thus provide a clue to help distinguish intrahepatic metastasis from the multicentric occurrence of HCC.

Aged↗

PubMed1996

Congenital mediastinal bronchogenic cyst with malignant transformation: an autopsy report.

A rare autopsy case of mediastinal bronchogenic cyst with malignant transformation is presented. The cyst had been located in the anterior mediastinum for at least 28 years in a 52 year old male. Chest X-ray findings showing rapid enlargement of the cyst and biopsy of the spine for lumbago made a clinical diagnosis as suspicious mediastinal cystic teratoma with malignant transformation metastasizing to the spine. Postmortem examination revealed that the cyst was located in the anterior mediastinum extending to the left pulmonary hilum and had no connection with the tracheobronchial tree. The cyst wall consisted of bronchus-like tissue including ciliated epithelium, hyaline cartilage, smooth muscle and mucoserous glands. There were no teratomatous components in the wall. Malignant tumor predominantly consisting of round cells occurred in the thickened cyst wall and grew into the cyst cavity with direct invasion of the lung and metastases to the liver, adrenal glands, bone marrow of the lumbar spine and lymph nodes. An immunohistochemical study showed that the tumor cells frequently expressed cytokeratin, epithelial membrane antigen and carcino-embryonic antigen, occasionally CA19-9, vimentin and neuron-specific enolase. From these findings, the tumor was diagnosed as undifferentiated carcinoma arising in the mediastinal bronchogenic cyst.

Bronchogenic Cyst↗

PubMed1996

Malignant eccrine poroma with multiple visceral metastases: report of a case with autopsy findings.

An autopsy case of malignant eccrine poroma (MEP) with multiple visceral metastases is reported. A flat, dark tumor of 1 cm in diameter developed on a pre-existing pigmented spot at the left side of the waist of a 58-year-old male. The histopathology suggested the tumor to be malignant melanoma. Nine years later, a painless swelling occurred in the left lower leg, resulting from the obstruction of lymphatics at the left inguinal region. The swelling continued and spread with pain, reaching the inguinal region. Two years later, several papules appeared around the left knee, from which an extensive lymphorrhea occurred. The histopathology of the resected papules suggested epidermoid carcinoma or trichilemmal carcinoma, mainly localized within the lymphatics of the upper dermis. Re-examination of the first skin tumor and electron microscopy of the tumor obtained at autopsy revealed that both tumors were MEP. Although the metastases to the local cutaneous regions and lymph nodes via the lymphatics occur in 20% of MEP, cases with multiple visceral metastases are very few.

Acrospiroma↗

PubMed1996

Responses of periodontal nerve terminals to experimentally induced occlusal trauma in rat molars: an immunohistochemical study using PGP 9.5 antibody.

The response of periodontal nerves to experimentally induced occlusal trauma in rat molars was assessed by immunohistochemistry for protein gene product 9.5 (PGP 9.5) at light and electron microscopic levels, and by computerized image analysis. The occlusal surface on the left upper first molar of 8-wk-old male Wistar rats was raised approximately 1 mm under ether anaesthesia. The rats were perfusion-fixed on d 1, 2, 3, 4, and 7 after bite-raising and then decalcified for 2-3 wk. Frozen sagittal cryostat sections were stained by the avidin-biotin complex method. By the second day after bite-raising many Ruffini endings were swollen and their outline unclear at the light microscopic level. Transmission electron microscopy disclosed PGP 9.5 reaction products within Ruffini endings that had unusually long cytoplasmic projections extending through enlarged slits of the Schwann sheaths and also diffuse extracellular PGP 9.5-immunoreactivity near the Ruffini endings. From d 2 to 4, thin nerve fibres on the pressure side of the periodontal ligament were orientated irregularly and had a prominent beaded appearance. An increase in beaded nerve terminals occurred at d 2-4 post elevation, and decreased later. These results suggest that occlusal trauma indices specific changes in the distribution and shape of nerve terminals in the periodontal ligament.

Animals↗

PubMed1996

Risk factors for hepatitis C virus infection among blood donors in an HIV-epidemic area in Thailand.

OBJECTIVE: The role of sexual transmission in hepatitis C virus (HCV) infection has not yet been completely elucidated. This study aimed to compare the risk factors for HCV and human immunodeficiency virus (HIV) infection in an HIV epidemic area of Thailand where HIV is mainly transmitted heterosexually. DESIGN AND SUBJECTS: Sera from 3053 blood donors were collected and tested for HCV and HIV between January and March 1994. Altogether 1756 (57.5%) of the donors were interviewed about demographics and several risk factors. RESULTS: The prevalence rates of HIV and HCV infections determined by antibody assays were 2.3% and 2.2%, respectively. Sexual risk factors were clearly shown among anti-HIV positive donors. These clear associations were not found, however, among anti-HCV positive donors. In contrast, previous histories of injecting drug use and being tattooed were found in some anti-HCV positive donors but less frequently in anti-HIV positive donors. CONCLUSIONS: Sexual transmission may play a relatively minor role in HCV transmission compared with HIV, in this area.

Adult↗

PubMed1996

IR and NMR analyses of hardening and maturation of glass-ionomer cement.

It has been reported that the silicate phase as well as the cross-linking of the polycarboxylic acid by aluminum and calcium ions played an important role in the hardening of glass-ionomer cement. The objective of this study was to investigate the structural change during hardening of the cements by means of infrared (IR) spectroscopy and solid-state nuclear magnetic resonance (NMR) spectroscopy and to confirm the role of the silica phase in the hardening of the cement. For that purpose, we measured the change in compressive strength of an experimental glass-ionomer cement, two commercial glass-ionomer cements, and a polycarboxylate cement and carried out 29Si and 27Al NMR analyses of the cement samples after the strength measurement. In the IR spectra during hardening, a characteristic band of the silicate network around 1000 cm-1 shifted toward high frequency with time. The spectrum after hardening was similar to that for a hydrated amorphous silica structure. The 27Al NMR analysis showed that Al3+ ion was tetrahedrally coordinated by oxygen in the original glass, but a part of the Al3+ ion was octahedrally coordinated after hardening to form Al polyacrylate gel. The chemical shift of Si in the 29Si NMR spectra also changed during hardening. The variation in the chemical shift reflected the structural change in the silicate network. The initial increase in compressive strength of the cement was mainly caused by polycarboxylate gel formation. However, it was concluded that the reconstruction of the silicate network contributed to the increase in strength with time during the period after the gelation by cross-linking was completed.

Compressive Strength↗

PubMed1996

Dendritic cells: a novel cellular component of the rat incisor enamel organ appearing in the late stages of enamel maturation.

Immunocompetent cells in the enamel organ of rat incisors were examined immunohistochemically using OX6, ED1, and ED2 monoclonal antibodies known to recognize the Class II MHC molecules, a monocyte-macrophage lineage, and residential macrophages, respectively. The OX6 immunopositive cells (MHC cells) were located exclusively in the enamel maturation zone. MHC cells increased in number in the incisal direction and occasionally extended cytoplasmic processes deep into the ameloblast layer. Migration of MHC cells in the ameloblast layer were also encountered. MHC cells lacked phagolysosomes and could be distinguished from typical macrophages. ED2 immunopositive cells were not seen in the enamel organ. ED1 positive cells displayed identical localization to MHC cells except that some appeared in the transitional zone. MHC cells could not be seen in the enamel organ of rat molar tooth germs. Our data confirmed the presence of a large population of "dendritic" immunocompetent cells in the enamel organ of rat incisors and characterized the ultrastructural features of these cells. Biological significance of the immunocompetent cells in the enamel organ during amelogenesis needs to be clarified.

Amelogenesis↗