Biomedical subjects

T Mikami

Publications and source records attributed to T Mikami.

At least 253 records · Page 14Linked to original sources

PubMed1998

[A case of transethmoidal meningocele showing increased activity of 99mTcHM-PAO at seizure attack].

A case of transethmoidal meningocele presenting seizure attack is reported. A 59-year-old man was admitted to our hospital because of seizure attack. On admission, he was neurologically free without right olfactory dysfunction. T2-weighted image of MRI showed high intensity signal area in right frontal base, and this signal increase herniated into the ethmoidal sinus. Then 3 DCT image clearly showed right frontal base bony defect. After admission, we compared brain activity in this patient during a seizure attack and resting state using SPECT. And we found increased activity in right frontal base using 99mTc HM-PAO. So it was suspected that indicated the focus of the seizure. During the operation a unilateral bony defect and hypoplastic olfactory nerve were observed, but there was no herniated brain tissue. The association of seizure with frontobasal meningoencephalocele is reported only two cases. In one of two cases, it is presumed that reactive gliosis was epileptogenesis. On the other hand, the relationship of the temporal meningoencephalocele to the genesis of temporal lobe seizure is suggested by the extension of gliosis to the amygdalohippocampal lesion. In our case, it is possible that reactive gliosis or scar of the cyst wall may be the focus of seizure. In terms of diagnosis, 3 DCT is useful to identify the bony defect. It makes easy to diagnose the front-basal encephaloceles.

Ethmoid Sinus↗

PubMed1998

Stereochemical structures of synthesized and natural plasmalogalactosylceramides from equine brain.

Modified galactosylceramide with a long-chain cyclic acetal at the sugar moiety, plasmalogalactosylceramide, was isolated from equine brain. To identify the isomeric stereostructure of the natural product, the plasmalo derivative was chemically synthesized from galactosylceramide through acetalization. The presence of cyclic acetal linkage, the linked position and length of the acetal chain of the synthesized and natural products were determined by proton nuclear magnetic resonance spectroscopy and fast-atom bombardment-mass spectrometry, as well as gas chromatography-mass spectrometry and gas-liquid chromatography. The orientation of the acetal chain linked to galactoside was characterized by connectivity between the cyclic acetal proton and ring proton(s) on the sugar moiety using the homonuclear Overhauser effect. This revealed that, of the two positional isomers of the acetal linkage with 4,6-O-acetal and 3,4-O-acetal derivatives obtained from the acetalization reaction, the former positional isomer, separated into two spots, was identified to 'endo'- and 'exo'-type acetal chains. In comparison to the NMR data of the synthesized derivative, equine brain acetalized lipid was found to be an 'endo'-type 4,6-O-acetal derivative.

Acetals↗

PubMed1998

[Usefulness of 123I-MIBG scintigraphy for prediction of effect of beta-blocker therapy in dilated cardiomyopathy].

To determine whether 123I-MIBG (MIBG) scintigraphy is useful for predicting the effect of beta-blocker therapy in patients with dilated cardiomyopathy (DCM), we studied MIBG scintigraphy in 11 controls and 9 patients with DCM before starting beta-blocker therapy. First, initial and delayed heart-to-mediastinum ratios (H/M ratio) of MIBG activity in patients with DCM were significantly lower than those in 11 controls, respectively (initial H/M; 1.8 +/- 0.3 vs. 2.1 +/- 0.3, p < 0.02, delayed H/M; 1.6 +/- 0.3 vs. 2.4 +/- 0.2, p < 0.0001), and MIBG washout rate from the heart was significantly higher in patients than in controls (washout rate; 33 +/- 7% vs. 22 +/- 4%, p < 0.0005). Second, beta-blocker therapy improved LVEF in 7 patients (improved group), while it resulted in deterioration of heart failure, followed by death in 2 patients (deteriorated group). Although initial and delayed H/M ratios in the improved group were not significantly different from those in the deteriorated group, respectively, MIBG washout rate was significantly higher in the deteriorated group than in the improved group (45 +/- 8% vs. 30 +/- 3%, p = 0.04). Our study suggests that DCM patients with markedly rapid MIBG clearance may be deteriorated by beta-blocker therapy. In contrast, there were no differences in LVEF and plasma norepinephrine between improved and deteriorated groups. In conclusion, 123I-MIBG scintigraphy is useful for predicting the effects of beta-blocker therapy in patients with DCM.

3-Iodobenzylguanidine↗

PubMed1997

Immunological and histological disorders in cats experimentally infected with feline immunodeficiency virus subtype B (TM2 stain).

Three conventional cats were experimentally infected with subtype B (TM2 strain) of FIV, and two conventional cats served as controls. The infected cats were examined immunologically 99-176 weeks post FIV inoculation (wpi) and histologically at 130 wpi. Two of the three infected cats exhibited lower CD4/CD8 T cell ratios and hypergammaglobulinemia compared with two control cats. Further, all the infected cats showed morphological changes in popliteal lymph nodes such as lymphoid depletion, atrophy and plasma cell hyperplasia. In addition, apoptosis was induced in peripheral blood mononuclear cells (PBMC) from the FIV-infected cats after in vitro culture for one or two days, but not in PBMC from uninfected cats. These observations indicate that FIV subtype B has the potential to induce some immunological and histological disorders in cats.

Animals↗

PubMed1997

Hemoglobin is utilized by Candida albicans in the hyphal form but not yeast form.

Hyphal cells of Candida albicans bound to human hemoglobin, but not the yeast cells. The amount of hemoglobin receptor was significantly higher on the hyphal cells than on the yeast cells. Only the hyphal cells of C. albicans used hemoglobin as a source of iron. The hemolytic factor was detected in the culture supernatant of the hyphal cell of C. albicans.

Animals↗

PubMed1997

Apoptosis, proliferative activity and Bcl-2 expression in Epstein-Barr-virus-positive non-Hodgkin's lymphomas.

In order to clarify the effects of Epstein-Barr virus (EBV) infection on apoptosis and proliferative activity of non-Hodgkin's lymphoma, 135 Japanese lymphoma cases were investigated for the presence of viral RNA and its correlation with bcl-2 protein (Bcl-2) expression. In addition, the role of EBV in lymphoma-genesis was also studied in terms of EBV genotyping and specific deletion in the gene for the latent membrane protein 1 (LMP-1). EBER-1 RNA in situ hybridization revealed EBV in 18 cases (13.3%), comprising 12 of 44 T cell (27.3%) and 6 of 91 B cell (6.6%) lymphomas. Type A EBV was found in all 18 cases (100%), and 17 of the 17 (100%) evaluable cases showed a 30-bp deletion within the 3' end of LMP-1. Comparison of apoptotic indices (AI), assessed by DNA nick-end labelling, and proliferative activity, estimated in terms of Ki-67 labelling and mitotic indices (KI and MI), demonstrated an overall correlation among AI, KI and MI increases in association with Bcl-2 negativity, indicating a close relation between apoptosis and proliferation. EBV-positive cases showed significantly elevated AI values, independent of Bcl-2 positivity, with no change in KI and MI. These results indicate that EBV in Japanese non-Hodgkin's lymphomas is exclusively of type A with a specific deletion in LMP-1 and that it tends to be present in T cell lymphomas. Moreover, EBV up-regulates apoptosis without any relation to Bcl-2 expression and exerts only minor effects on proliferation.

Apoptosis↗

PubMed1997

Expansion of the IR in the chloroplast genomes of buckwheat species is due to incorporation of an SSC sequence that could be mediated by an inversion.

The chloroplast genomes in buckwheat species contain large inverted repeats which are at least 4 kbp longer than the majority of those in land plants. The length of the buckwheat inverted repeats was attributable to an additional region located adjacent to the borders of the small single-copy region. We have cloned and sequenced a 5. 2-kbp SmaI fragment corresponding to this extra region in the inverted repeats. A homology search revealed that the sequence of the SmaI fragment is highly homologous to one side of the small single-copy region of the inverted repeats in dicot chloroplast DNAs such as tobacco and beechdrops. Interestingly, a 3.7-kbp segment in the middle of the SmaI fragment is inserted in the opposite orientation relative to those of the other dicot species, and 17-bp direct repeats are found located at both the ends of the additional region. These results suggest that expansion of the inverted repeats in buckwheat chloroplast DNA might have been associated with an inversion.

Chloroplasts↗

PubMed1997

Expression of the feline herpesvirus type 1 ICP4 gene is controlled by two alternative promoters.

Feline herpesvirus type 1 (FHV-1) produces a single 5.4 kb immediate-early (IE) transcript encoding FHV-1 ICP4 which acts as a trans-acting factor [Kawaguchi et al. (1994) Virology 204: 430-435]. Our earlier study has shown that the FHV-1 IE transcript is spliced in the leader region and the FHV-1 IE gene product (ICP4) down-regulates its own promoter through the region which includes its transcription initiation site [Kawaguchi et al. (1996) J Vet Med Sci 58: 715-721]. Here we investigated FHV-1 ICP4 gene expression throughout FHV-1 productive infection and demonstrated that (i) a novel promoter is located downstream of the IE promoter and an early transcript is transcribed from this promoter region, (ii) a negative regulatory element, which is composed of a 20 bp direct repeat unit repeated 20 times, is located between the two promoters and the repeat unit shows high homology to a motif called direct repeat 2 in "a" sequence of herpes simplex virus type 1, (iii) the IE promoter and synthesis of the IE mRNA appear to be turned off after IE phase and the second promoter becomes active during early and late stages, and (iv) a gene product expressed only by the second promoter also possesses regulatory function. These findings indicate that expression of the FHV-1 ICP4 gene is alternatively regulated by the two promoters.

Animals↗

PubMed1997

Analysis of canine herpesvirus gB, gC and gD expressed by a recombinant vaccinia virus.

The genes encoding the canine herpesvirus (CHV) glycoprotein B (gB), gC and gD homologues have been reported already. However, products of these genes have not been identified yet. Previously, we have identified three CHV glycoproteins, gp 145/112, gp80 and gp47 using a panel of monoclonal antibodies (MAbs). To determine which CHV glycoprotein corresponds to gB, gC or gD, the putative genes of gB, gC, and gD of CHV were inserted into the thymidine kinase gene of vaccinia virus LC16mO strain under the control of the early-late promoter for the vaccinia virus 7.5-kilodalton polypeptide. We demonstrated here that gp145/112, gp80 and gp47 were the translation products of the CHV gB, gC and gD genes, respectively. The antigenic authenticity of recombinant gB, gC and gD were confirmed by a panel of MAbs specific for each glycoprotein produced in CHV-infected cells. Immunization of mice with these recombinants produced high titers of neutralizing antibodies against CHV. These results suggest that recombinant vaccinia viruses expressing CHV gB, gC and gD may be useful to develop a vaccine to control CHV infection.

Animals↗

PubMed1997

Angiotensinogen gene polymorphism in Japanese patients with hypertrophic cardiomyopathy.

To examine the contribution of the renin-angiotensin system to hypertrophic cardiomyopathy (HCM), we studied 96 patients with HCM (mean age 50 years, 55% male), 105 of their unaffected siblings and offspring, and 160 healthy subjects without known hypertension and left ventricular hypertrophy (LVH) who were frequency matched to cases by age and sex. Patients were divided into familial or sporadic HCM (FHCM or SHCM) groups with or without affected members of their family. The region of interest in the angiotensinogen (AGT) gene, the missense mutation with methione-to-threonine amino acid substitution at codon 235 in angiotensinogen (M235T), was amplified by polymerase chain reaction with the use of allele-specific oligonucleotide primers flanking the polymorphic region of the AGT gene to amplify template deoxyribonucleic acid prepared from peripheral leukocytes. The T allele frequency was higher in the SHCM group than in unaffected siblings and offspring (88% vs 78%, X2 = 4.6, p < 0.05). The M allele frequency was higher in unaffected siblings and offspring than in patients with SHCM (23% vs 12%, X2 = 4.6, p < 0.05). The T allele frequency among unaffected siblings and offspring was similar to that observed in healthy subjects (78% vs 78%). We conclude that HCM, especially in sporadic cases, is partially determined by genetic disposition. The molecular variant of angiotensinogen T235 seems to be a predisposing factor for cardiac hypertrophy in HCM and carries an approximately twofold increased risk.

Adult↗

PubMed1997

Histopathological features of canine distemper recently observed in Japan.

Eleven dogs with canine distemper (CD) from the Chubu region of Japan and the Tokyo area were examined. Clinically, respiratory and neurological signs were present in all animals. Histopathologically, all showed characteristic CD lesions of bronchopneumonia and demyelinating encephalitis. However, some differences in gastrointestinal abnormalities were observed. Three out of four dogs from the Chubu region had severe diarrhoea and gastroenteritis, associated with numerous eosinophilic inclusion bodies in the mucosal epithelia. The remaining dog from this area showed vomiting, but not diarrhoea, and also had a number of intraepithelial inclusion bodies in the gastric and intestinal mucosa. In contrast, the seven dogs from the Tokyo area showed neither gastrointestinal symptoms nor intraepithelial inclusions in the stomach or intestine. Immunohistochemical examination for CD virus antigen, however, revealed that these seven dogs had immunoreactive products in the mucosal epithelia, suggesting that the epithelial cells had either a low level of infection with CD virus or were infected with a less cytopathogenic virus. These findings suggest that the dogs in this study were probably affected by two distinct types of CD, in terms of epitheliotropism and cytopathogenic effects on the gastrointestinal tissues.

Animals↗

PubMed1997

The gastric hypercellular microleiomyoma as a precursor lesion for clinical gastrointestinal stromal tumors.

Differentiation features and proliferation activity of 67 gastric microleiomyomas (microLMs) and 53 clinical gastrointestinal stromal tumors (GISTs) of the stomach were compared. The 67 microLMs were divided into two categories on the basis of cellularity: 53 hypocellular and 14 hypercellular types, and the 39 GISTs were divided into 13 low-grade and 40 high-grade lesions. Immunohistochemically, 49 hypocellular microLMs (92%) were positive for alpha-smooth muscle actin and desmin, whereas only 16 (30%) were stained for vimentin. Conversely, all 14 hypercellular microLMs were positive for vimentin, and only one (7%) was positive for alpha-smooth muscle actin and desmin. Five low-grade (38%) and 14 high-grade GISTs (35%) were positive for alpha-smooth muscle actin, and 12 low-grade (92%) and all 40 high-grade GISTs were stained for vimentin. CD34 was positive in 10 hypocellular microLMs (19%), all 14 hypercellular microLMs, 10 low-grade GISTs (77%), and 38 high-grade GISTs (95%). Hypercellular microLM thus showed similarities to clinical GIST and also exhibited significantly higher proliferation activity than hypocellular microLM on analysis of the Ki-67 labeling index and argyrophilic nucleolar organizer regions staining. The findings indicate that the hypercellular microLM may be a direct precursor for clinical GIST, both showing a primitive mesenchymal cell nature.

Cell Division↗

PubMed1997

Cellular and molecular mechanisms of IL-5 synthesis in atopic diseases: a study with allergen-specific human helper T cells.

BACKGROUND: Cytokines produced by helper T cells are intimately involved in chronic allergic diseases associated with eosinophilic inflammation. OBJECTIVE: We investigated the production of IL-5, a potent growth factor and chemotactic factor for eosinophils, by CD4+ T lymphocytes in patients with asthma. METHODS: Allergen-specific T cell clones and T cell hybridomas were established from the peripheral blood lymphocytes of patients with asthma, and the responses to various stimuli were determined. RESULTS: After nonspecific stimulation, IL-5 production by CD4+ T cells from both atopic and nonatopic subjects with asthma was significantly enhanced compared with that by cells from healthy controls. Peripheral blood mononuclear cells from atopic asthma patients both proliferated and produced IL-5 after incubation with mite allergen, suggesting that mite-specific helper T cells were involved in the eosinophilic inflammation of atopic asthma. A human IL-5 promoter/enhancer luciferase gene construct transfected into IL-5-producing T cell clones was clearly transcribed after stimulation, indicating that the 515 base pair IL-5 gene segment upstream of the coding region was sufficient to respond to activating signals in human helper T cells. The same gene segment was not transcribed in IL-5-nonproducing T cell clones, suggesting that human T cell IL-5 synthesis is regulated at the transcriptional level. Experiments with T cell hybridomas confirmed these findings and suggested that a unique transcription factor may be essential for human IL-5 gene transcription. CONCLUSION: Enhanced IL-5 production by helper T cells seems to cause the eosinophilic inflammation of both atopic and nonatopic asthma. Elucidation of IL-5-specific regulatory mechanisms may facilitate the development of novel treatments for allergic diseases associated with eosinophilic inflammation.

Adult↗

PubMed1997

Characterization and expression of the Marek's disease virus serotype 2 glycoprotein E in recombinant baculovirus-infected cells: initial analysis of its DNA sequence and antigenic properties.

In Marek's disease virus (MDV) serotype 2 (MDV2) genome, a gene equivalent to the glycoprotein E (gE) of other alphaherpesviruses was identified and sequenced. The primary translation product comprises 488 amino acids with a M(r) of 54.3 kDa. The predicted amino acid sequence possesses several characteristics typical of membrane glycoproteins, including a N-terminal hydrophobic signal sequence, C-terminal transmembrane and cytoplasmic domains, and extra-cellular region containing four potential N-linked glycosylation sites. Compared with other MDV serotypes, MDV2 gE showed 47.3% identity with MDV1 gE, and 38.9% identity with HVT gE at the amino acid level. In transcriptional analyses, a 2.0 kb mRNA which starts between 65 and 86 bps upstream of the potential translational initiation codon of gE was identified as the gE-specific transcript. By a recombinant baculovirus, this potential gE coding region was expressed as several specific products from 66 to 72 kDa. These products were susceptible to tunicamycin treatment, indicating that they were glycoprotein in nature. Further, the expressed gE reacted with all chicken-antisera raised to each of the three serotypes of MDV (strains GA, SB-1, and FC126), suggesting that gE is expressed by all three serotypes of MDV in infected cells and conserves common antigenic epitope(s) beyond those that are serotype specific.

Amino Acid Sequence↗

PubMed1997

The effects of treatment with chemical agents or infection with feline viruses on protein-binding properties of the feline immunodeficiency virus long terminal repeat.

The effects of treatment with chemical agents or infection with feline viruses on protein-binding properties of the feline immunodeficiency virus (FIV) long terminal repeat (LTR) were examined by gel-mobility-shift assays using oligonucleotides designed to represent putative AP-1 or ATF motif from the FIV LTR. Infection with FIV led to less nuclear proteins binding to the AP-1 and ATF sites, suggesting that proteins binding to the sites were consumed or suppressed by FIV-replication in FIV-infected cells. Nuclear proteins that bind to the AP-1 or ATF site were examined by using extracts from Crandell feline kidney (CRFK) cells treated with TPA (a phorbol ester; a strong activator of protein kinase C) or forskolin (an inducer of cyclic-AMP), or infection with feline herpesvirus type 1 (FHV-1). Although TPA or forskolin treatment moderately increased the level of both proteins that bound to AP-1 and ATF sites, FHV-1 infection markedly changed the protein-binding patterns of the sites. Furthermore, FHV-1-induced proteins that bind adjacent to the transcriptional initiation site of FIV promoter were also observed in FHV-1-infected CRFK cells, suggesting that the FHV-1-induced-proteins affects the transcription of FIV through the AP-1, ATF and leader sequences.

Animals↗

PubMed1997

Heparin-binding activity of feline herpesvirus type 1 glycoproteins.

Feline herpesvirus type 1 (FHV-1) possesses a very narrow host range, but the mechanism of its infection has not yet been analyzed. Heparan sulfate on the cell surface serves as a receptor for several herpesviruses. In this study, we determined that infection of FHV-1 is inhibited by addition of soluble heparin in cells cultures. Using heparin-affinity column, it was shown that FHV-1 gC is a major heparin-binding protein, and FHV-1 gB weakly binds to heparin, but FHV-1 gD does not. Furthermore, the FHV-1 gC expressed in insect cells can also bind to heparin despite of being immature glycosylation. Our results suggested that FHV-1 gC can bind to heparin as observed in other herpesviruses and that glycosylation of the gC does not affect its heparin-binding activity. In addition, mice immunized with the gC expressed in insect cells produced complement-dependent virus-neutralizing antibody.

Alphaherpesvirinae↗

PubMed1997

Transient expression of FGF-5 mRNA in the rat cerebellar cortex during post-natal development.

Previously, we showed that fibroblast growth factor (FGF) receptor-4 mRNA was transiently expressed in proliferative granule cells of the external granule layer of the rat cerebellar cortex during early post-natal development (A. Miyake et al., Mol. Brain Res., 31 (1995) 95-100). In this study, we examined the expression of FGF-5 mRNA in the rat brain during post-natal development by in situ hybridization. FGF-5 mRNA was transiently expressed in granule cells of the internal granule layer of the cerebellar cortex during early post-natal development. The temporal sequence of FGF-5 mRNA expression was similar to that of FGFR-4 mRNA expression. As the proliferation of granule cells in the external granule layer and their migration through the molecular layer into the internal granule layer actively occur during these periods, the present findings suggest that FGF-5 as well as FGFR-4 might play important roles in the proliferation and/or migration of granule cells during the post-natal development of the cerebellar cortex.

Animals↗

PubMed1997

Calcifying epithelioma (pilomatrixoma) of the head and neck: analysis of 37 cases.

OBJECTIVE: To review all cases of pilomatrixoma (calcifying epithelioma) of the head and neck published in Japanese dental journals 1977-1994. DESIGN: Retrospective review. SETTING: University hospital, Japan. SUBJECTS: 37 Patients with 38 tumours, mean age 23 years, female: male ratio 2.4:1. INTERVENTIONS: Enucleation alone (n=29, 78%), excision including covering skin (n=7, 19%), or excision including superficial lobe of parotid (n=1, 3%). MAIN OUTCOME MEASURE: Presentation, site, recurrence, and histological features. RESULTS: Two patients had multiple tumours (5%). Most of the tumours were firm nodules covered with normal skin varying in size from 5 to 30 mm. The most common site was the preauricular region; 22 (58%) were in the anterior part. The follow up period ranged from 7 to 43 months during which there was only one recurrence. Tumours were encapsulated and solid composed of either shadow and basophilic cells or shadow cells alone, and the stroma contained varying amounts of calcification, ossification, and keratinization. CONCLUSIONS: The diagnosis should be suspected when the mass is adherent to the skin but not fixed to the underlying tissue. It is difficult to distinguish between benign and malignant tumours by imaging methods alone, so the recommended treatment must be complete excision including adherent skin.

Adolescent↗