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Biomedical subjects

T Nagano

Publications and source records attributed to T Nagano.

At least 145 records · Page 8Linked to original sources
PubMed1997

Identification of pathogenic strains within serogroups of Yersinia pseudotuberculosis and the presence of non-pathogenic strains isolated from animals and the environment.

The existence of apathogenic strains of Yersinia pseudotuberculosis (Yp) has not so far been reported. Recently, the authors characterized new serogroups and a new subgroup in Yp, that is, O9, O10, O12, O13 and O14 and O1c, and the pathogenicity of these new strains was of interest. A total of 137 strains of serogroups O1c, O6, O7, O9, O10, O11, O12, O13 and O14 of Yp were investigated for their pathogenicity in vivo and in vitro. Although catalase activity and the inv gene were detected in all strains except those of groups O13 and O14, only a few strains, from serogroups O6 and O10 caused severe infection in mice. The remaining strains caused no mortality or severe infection even when they grew in limited tissues of infected mice. All the strains of Yp not possessing the virulence plasmid p YV caused no severe infection in mice. It is evident that less pathogenic Yp exists and that not only pathogenic but also less pathogenic Yp organisms exist in the same serogroup.

Animals↗
PubMed1997

Neurotrophic factors in brain synaptic plasticity.

Various intercellular signals influence the strength and mode of synaptic neurotransmission and contribute to synaptic plasticity. Such signals include neurotransmitters, gas molecules, and protein factors. In response to certain neural stimuli, these molecules are liberated from presynaptic and postsynaptic neurons, glial cells, and immune cells and synergistically alter synaptic neurotransmission over the long or short term. The short-term actions often involve presynaptic activities leading to long-term potentiation. However, it is now known that various protein factors including growth factors, cytokines, and neurotrophic factors can produce not only such short-term effects but also long-term synaptic modification of presynaptic and postsynaptic neurons by altering the production of neurotransmitters and the expression of their receptors or synaptic organization. The present review focuses on these intercellular protein factors and discusses the way in which they regulate synaptic plasticity.

Animals↗
PubMed1997

Effects of the alpha-/beta-blocking agent carvedilol on hepatic and systemic hemodynamics in patients with cirrhosis and portal hypertension.

To enhance the portal hypotensive effect of nonselective beta-blockers, combinations of vasoactive agents with different mechanisms should be considered. The effect of carvedilol (CAS 72956-09-3, Artist), and alpha-/beta-blocking agent, on hepatic and systemic hemodynamics in 10 patients with portal hypertension was evaluated. After administration of carvedilol, the hepatic venous pressure gradient (HVPG) decreased from 15.9 +/- 3.2 mmHg to 13.3 +/- 4.0 mmHg (mean +/- SD) at 60 min (-15%) and to 12.9 +/- 3.0 mmHg at 90 min (-17%, p < 0.05). However, only 5 patients showed a decrease of HVPG by more than 20% at 60 or 90 min. The estimated hepatic blood flow (EHBF) was not significantly reduced. In contrast, heart rate (-8%, p < 0.05), mean arterial pressure (-10%, p < 0.01), and cardiac index (CI) (-8%, p < 0.05) were all reduced at 90 min, while total systemic vascular resistance was not altered. The reduction of HVPG was significantly correlated with the decrease of CI (r = 0.6415, p < 0.05). The portal hypotensive effect of carvedilol may mainly result from a reduction of CI. However, because of the greater reduction of HVPG than that of CI, other additive actions were suggested.

Adrenergic alpha-Antagonists↗
PubMed1997

Expression of macrophage colony-stimulating factor and its receptor in hepatic granulomas of Kupffer-cell-depleted mice.

In mice administered with liposome-entrapped dichloromethylene diphosphonate, which depletes Kupffer cells, the size and the number of zymosan-induced granulomas in the liver were smaller than in untreated mice. The number of macrophage precursors, as detected by the monoclonal antibodies for macrophage precursors, increased after zymosan injection in both groups of mice, proliferated, and differentiated into macrophages. Expression of macrophage colony-stimulating factor (M-CSF), interleukin-1, monocyte chemoattractant protein-1, tumor necrosis factor-alpha, and interferon-gamma mRNA was enhanced in the stage of granuloma formation in the control mouse liver, whereas it was suppressed in Kupffer-cell-depleted mice. However, M-CSF mRNA expression was increased in the Kupffer-cell-depleted mice to form granulomas in the late stages. In situ hybridization demonstrated the expression of M-CSF mRNA and c-fms mRNA in Kupffer cells and monocyte-derived macrophages in the sinusoid and granulomas. The concentration of M-CSF in serum of zymosan-injected control mice was within normal range, but that of zymosan-treated or untreated Kupffer-cell-depleted mice was markedly elevated at day 1. These findings imply that Kupffer cells are indispensable for granuloma formation and produce various cytokines including M-CSF. The local production and consumption of M-CSF in the liver may play a crucial role in granulomatous inflammation.

Animals↗
PubMed1997

[Medulloblastoma originating from the superior cerebellar peduncle: a case report].

A rare case of medulloblastoma originating from the superior cerebellar peduncle is reported. After tilting her neck to the right, a 4-year-old girl experienced a left-side hemiparesis for 3 months. Computed tomography (CT) scan and magnetic resonance image (MRI) showed an enhanced mass in the left tentorial incisura. The preoperative diagnosis was trochlear nerve neurinoma or tentorial meningioma, while the postoperative pathological diagnosis was medulloblastoma. Since medulloblastoma is thought to originate from the external granular layer, it is speculated that the external granular layer migrated through the superior cerebellar peduncle and changed to medulloblastoma.

Cerebellar Neoplasms↗
PubMed1997

[A case of idiopathic hypereosinophilic syndrome with special reference to mental disorders and brain images].

We reported a case of idiopathic hypereosinophilic syndrome with psychiatric symptoms and abnormal areas in subcortical white matter on brain MRI. The 25-year-old man was referred to us because of fever, confusional state and emotional incontinence. He soon became apathetic and emotionless. While he was confused, we studied brain CT twice and brain MRI four times. In deep white matter around the lateral ventricles and the cortices of parietal lobe, occipital lobe and cerebellar hemispheres, T1-weighted MRI revealed low intensity areas and T2-weighted MRI showed high intensity areas. After gadolinium infusion, some above-stated areas were enhanced. The lesions in the deep white matter disappeared when symptoms diminished, while lesions in the occipital cortex remained unchanged. Brain MRI studies were beneficial and useful to analyse the rare idiopathic hypereosinophilic syndrome with psychic disorders.

Adult↗
PubMed1996

Binding specificity of Lactobacillus to glycolipids.

Lactobacillus, a representative useful bacterium, in the intestinal tract was found to bind to some specific glycosphingolipids, like the pathogenic intestinal bacteria. Thin layer chromatography overlay assays using rabbit antiserum against Lactobacillus casei revealed that the bacteria bound to GA1 and trihexosylceramide strongly, but not to any gangliosides. The bacteria generally bound to glycosphingolipids having short sugar chains and galactosyl moiety in the non-reducing terminal. L.casei did not bind to GM1, but bound to the product after sialidase treatment, GA1. This indicated that sialic acid inhibited the adhesion of L.casei to tissues. L.casei actually bound nonacid glycosphingolipids but not acid glycosphingolipids extracted from the small intestinal mucosa of rats.

Animals↗
PubMed1996

Singlet oxygen (1 delta g) generation from coproporphyrin in Propionibacterium acnes on irradiation.

Although singlet oxygen has been postulated to be a highly reactive and toxic intermediate, there has been no evidence of considerable generation of singlet oxygen in vivo level except for special cases. In this work, we firstly measured the near-infrared emission spectra corresponding to the O2(1 delta g) --> O2(3 epsilon g-) transition of singlet oxygen of cutaneous Propionibacterium acnes (P. acnes) porphyrin under laser excitation. A comparison of the singlet oxygen production of coproporphyrin, which is produced predominantly from P. acnes, with that of other photosensitizers revealed coproporphyrin to be a highly efficient singlet oxygen generator under ultraviolet light A irradiation on the skin. These results suggest that singlet oxygen can be generated on the skin surface from P. acnes porphyrin under ultraviolet irradiation and induce serious damage to the skin.

Coproporphyrins↗
PubMed1996

Destruction of cholera toxin receptor on HeLa cell membrane using microbial endoglycoceramidase.

The sensitivity of HeLa cells to cholera toxin decreased by Corynebacterium sp. endoglycoceramidase treatment. This endo-enzyme destroyed the cholera toxin receptor, ganglioside G(M1), on the cell surface membrane by liberating intact oligosaccharide from it, which was confirmed by the decrease of intracellular cAMP accumulation and the results of the analysis of released oligosaccharide with a combination of pyridylamination method and HPLC. Fluorescence microscopy using the immunofluorescence method revealed that the amount of cholera toxin attached to the cells decreased in endoglycoceramidase-treated cells. The enzyme acted on cellular glycosphingolipids without addition of any activator protein which is required by other similar enzymes. Corynebacterium endoglycoceramidase is a useful tool to elucidate the function of glycosphingolipids on the cell surface in situ.

Cell Membrane↗
PubMed1996

Immunohistochemical localization of cell adhesion molecules and cell-cell contact proteins during regeneration of the rat optic nerve induced by sciatic nerve autotransplantation.

BACKGROUND: The central nervous system neurons of adult mammals are known to regenerate into peripheral nerve autograft. The localization of cell adhesion molecules and cell-cell contact proteins were studied during axonal regeneration induced by sciatic nerve autotransplantation. METHODS: A sciatic nerve autograft was anastomosed to the proximal stump of the transected rat optic nerve. Immunofluorescence microscopy, thin sectioning, and immunoelectron microscopy with the preembedding method and ultrathin cryosections were used to localize cell adhesion molecules (L1; neural cell adhesion molecule, NCAM; myelin-associated glycoprotein, MAG) and cell-cell contact proteins (connexins 32, 43, ZO-1) at 3 days to 4 weeks postoperation. RESULTS: Most regenerating axons contacted astrocytes in the optic nerve and Schwann cells in the graft. Immunoreactivity of NCAM was widely distributed along the surface of axons, astrocytes, Schwann cells, and perineurial cells. The L1 immunoreactivity was confined to the interface of axon-astrocyte and of axon-Schwann cell. MAG immunoreactivity was seen at the interface of axon and myelin within the graft. Connexins 32, 43, and ZO-1 immunoreactivities were observed at contact sites between axons and Schwann cells within the graft. CONCLUSIONS: Cell adhesion molecules (L1, NCAM, MAG) are localized at the cell surface of regenerating axons, astrocytes, and Schwann cells during optic nerve regeneration elicited by peripheral nerve graft. Cell-cell contact proteins (connexins 32, 43, ZO-1) are present at the interface between axons and Schwann cells in the graft. Our results suggest that these molecules are involved in cell adhesion events during optic nerve regeneration.

Animals↗
PubMed1996

E. coli endotoxin enhances cardiomyopathy in rats with chronic alcohol consumption.

The purpose of the study was to show whether it was possible to produce alcoholic cardiomyopathy by short-term alcohol ingestion combined with an infinitesimally low endotoxin injection. Wistar rats were fed an alcoholic liquid diet according to the formula of Lieber and Decarli, and challenged with an injection of E. coli lipopolysaccharide (LPS) endotoxin (1.0 microgram/g body weight per day for ten weeks). After ten weeks alcohol diet combined with LPS challenge, light microscopical examination showed changes commonly seen in alcoholic cardiomyopathy such as hypertrophy, oedema and disarray of myofibers. By electron microscopy, degeneration of mitochondria and degeneration of myocardial fibers were observed, the latter showing disturbance of the myofibrilla arrangement and interstitial fibrosis. Rats on an alcoholic liquid diet and rats challenged with a single identical doses of LPS did not show characteristic histological findings of alcoholic cardiomyopathy. These results suggest that short-term alcohol ingestion combined with an infinitesimally low endotoxin injection experimentally produces alcoholic cardiomyopathy, and may support the idea that endotoxin plays an important role in the aetiology of alcoholic cardiomyopathy.

Alcoholism↗
PubMed1996

Expression of p53 protein in melanoma progression.

p53, A tumor suppressor gene, has been documented as the most frequently mutated gene in human cancers including non-melanoma skin tumors. It has been controversial whether the p53 gene mutation plays a major role for melanoma genesis. To examine the role of p53 in human malignant melanoma carcinogenesis, we performed immunohistochemical analysis using anti-p53 antibodies (CM-1 and DO-7) in microwaved paraffin sections. When cases having more than 1% reactive cells were regarded as positive, immunohistochemical analysis revealed that in primary melanomas 14 of 51 (27%) were positive with CM-1 or 15 of 51 (29%) were positive with DO-7. Tumor thickness of primary melanomas in p53 positive cases was significantly thicker than that in p53 negative cases. In metastatic melanomas, 35 of 41 (85%) lymph node metastases were positive with either antibody and in skin metastases 16 of 28 (57%) lesions with CM-1 or 18 of 28 (64%) lesions with DO-7 were positive. The mean percentages of reactive cells were 2.3% in primary lesions and 4.9% in metastases. The incidence of positivity was significantly higher in metastases than primary lesions. In 10 cases examined, with both primary and metastatic melanoma, 3 cases were negative in both lesions and 1 case was positive in both lesions, while 6 cases were negative in the primary lesions and positive only in metastatic lesions. Four Spitz nevi, 6 dysplastic nevi and 11 common nevi were all negative. These data suggest that the expression of p53 protein may be a late event in melanoma progression.

Disease Progression↗
PubMed1996

Applying very high resolution microfocus X-ray CT and 3-D reconstruction to the human auditory apparatus.

Conventional high-resolution X-ray computed tomography (XCT) is an important medical technique because it provides sectional images (tomograms) of internal structures without destroying the specimen. However, it is difficult to observe and to analyze fine structures less than a few cubic millimeters in size because of its low spatial resolution of 0.4 mm. Overcoming this problem would not only enable visualization of human anatomical structures in living subjects by means of computer images but would make it possible to obtain the equivalent of microscopic images by XCT without making microscopic sections of biopsy material, which would allow the examination of the entire body and detection of focal lesions at an early stage. Bonse et al. and Kinney et al. studied absorption contrast microtomography by using synchrotron radiation and achieved 8-microns spatial resolution in human cancellous bone. Recently, Momose et al. reported examining the soft tissue of cancerous rabbit liver by a modification of the phase-contrast technique using synchrotron radiation with a spatial resolution of 30 microns (ref. 4). However, the equipment for synchrotron radiation requires a great deal of space and is very expensive. Aoki et al., on a different tack, reported microtomography of frog embryos by using a conventional laboratory microfocus X-ray source with a spot size of about 2 microns (ref. 5). As no human tomographic studies by superresolution microfocus XCT (MFXCT) using a normal open-type X-ray source have been reported, we tried using MFXCT with a maximum experimental spatial resolution of 2.5 microns, especially designed for industrial use, on the auditory ossicles of a human fetus, the smallest and lightest bones in the skeletal system. No XCT studies of fetal auditory ossicles have been reported to date. The fine tomograms with three-dimensional reconstructions obtained showed the existence of an apparently previously undescribed joint between the tympanic ring and the anterior process of the malleus. We hope the early development of this MFXCT for clinical use will make a great contribution to medicine.

Auditory Pathways↗
PubMed1996

Epitope analysis of HLA-DR-restricted helper T-cell responses to Der p II, a major allergen molecule of Dermatophagoides pteronyssinus.

T-cell epitopes of Der p II, a major allergen of Dermatophagoides pteronyssinus, were analyzed by using human T-cell clones. We tested 38 cloned T cells from two Japanese patients with allergic rhinitis, and identified at least two peptides (K33-T47 and I58-C73) as helper T-cell epitopes. The former epitope was shown to be restricted by HLA-DRB1*1502, and the latter by HLA-DRB1*0405, both of which are typical Japanese HLA-DR alleles, suggesting that those T-cell epitopes might be important for the onset of house-dust mite allergy in the Japanese population. We prepared 15 analog peptides of the HLA- DRB1*1502-restricted 15-mer peptide. Of those 15 residues, five (F35, L37, A39, F41, and E42) were critical for the epitope activity, and three residues (F35, A39, and E42) seemed to be included in anchor motifs for HLA-DRB1*1502. The epitope peptide was also recognized by HLA-DRB1*1502-positive healthy donors; however, only allergic T cells showed Th2 functions. Antigen-presenting cells of nonallergic donors were able to activate allergic T cells to express Th2 function. This seemed to suggest that antigen recognition of T cells, as well as additional unknown factors which promote Th2, rather than Th1, responses, might be important for the onset of house-dust mite allergy.

Allergens↗
PubMed1996

Elcatonin raises levels of vasoactive intestinal peptide in human plasma.

Elcatonin, used for treatment of hypercalcaemia, Paget's disease and osteoporosis, causes flushing of the face and hands. To determine whether this was because of increased levels of vasoactive intestinal peptide, which is known to induce vasodilation, the effect of elcatonin on the plasma levels of vasoactive intestinal peptide was studied in five healthy volunteers. After a single intramuscular administration of elcatonin (20 int units), peak plasma elcatonin levels (approx. 30 pg mL-1) were achieved 30 min after injection. Plasma vasoactive intestinal peptide concentrations rose similarly with peak levels of about 17 pg mL-1 after 30 min. Side-effects such as cutaneous flushing (most obvious in the face and hands) occurred to an extent dependent on the amount of elcatonin administered, and declined over 45 min in parallel with the fate of plasma vasoactive intestinal peptide. The side-effects of elcatonin, especially cutaneous flushing, seem to be closely connected with vasoactive intestinal peptide.

Adult↗
PubMed1996

Nitric oxide release from kidneys of hypertensive rats treated with imidapril.

To examine whether endothelial dysfunction in hypertension is reversible or not, we studied the effects of imidapril, an angiotensin-converting enzyme inhibitor, on nitric oxide release in stroke-prone spontaneously hypertensive rats (SHR) and deoxycorticosterone acetate (DOCA)-salt hypertensive rats. After a 4-week treatment with imidapril (1 or 10 mg/d SC) or vehicle, acetylcholine-induced vasodilation and nitric oxide release in the isolated kidneys were determined. Nitric oxide release was measured by a chemiluminescense assay. Imidapril lowered blood pressure in stroke-prone SHR in a dose-dependent manner. Untreated stroke-prone SHR exhibited significantly attenuated responses to acetylcholine (10(-8) mol/L) of both renal perfusion pressure (stroke-prone SHE 42 +/- 4% versus Wistar-Kyoto rats [WKY] 58 +/- 4% [mean +/- SE], P < .01) and nitric oxide release (stroke-prone SHR +7.6 +/- 2.1 versus WKY +29.7 +/- 9.7 fmol/min per gram of kidney wt, P < .01). Imidapril at 10 mg/d significantly increased acetylcholine-induced renal vasodilation and nitric oxide release in stroke-prone SHR (renal perfusion pressure, 56 +/- 3%; nitric oxide release, +27.1 +/- 6.4 fmol/min per gram of kidney wt; both P < .01 versus stroke-prone SHR treated with vehicle). On the other hand, imidapril neither decreased blood pressure nor changed nitric oxide release induced by acetylcholine in DOCA-salt hypertensive rats. Staining for endothelial nitric oxide synthase and brain nitric oxide synthase was clearly detected in the kidneys of both stroke-prone SHR and WKY, whereas staining intensity was weaker in DOCA-salt hypertensive rats. Inducible nitric oxide synthase immunoreactivity was barely noticeable in any type of rat. Thus, imidapril restored endothelial damage by pressure-dependent mechanisms. Most of the nitric oxide detected in the perfusate seemed to be derived from constitutive nitric oxide synthase.

Angiotensin-Converting Enzyme Inhibitors↗