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Biomedical subjects

T Takimoto

Publications and source records attributed to T Takimoto.

At least 55 records · Page 3Linked to original sources
PubMed1994

Mice lacking CD8+ T cells develop greater numbers of IgA-producing cells in response to a respiratory virus infection.

Antibody production profiles have been compared for Sendai virus infection of normal mice and mice that lack CD8+ T cells as a consequence of treatment with a lymphocyte subset-specific monoclonal antibody or homozygous disruption of the beta 2-microglobulin (beta 2-m(-/-)) gene encoding the light chain of the class I major histocompatibility complex glycoprotein. Using the single-cell ELISPOT assay, we show a relative increase in IgA antibody forming cell (AFC) numbers in the mediastinal lymph node (MLN), spleen, and bone marrow of the CD8-depleted mice. This is reflected in higher serum IgA titers. Similarly, secondary infection with a large dose of Sendai virus leads to greater prevalence of virus-specific IgA AFCs as early as Day 5 postinfection in the beta 2-m(-/-) mice. Also, in primed beta 2-m(-/-) mice challenged with vaccinia constructs containing the genes for the hemagglutinin-neuraminidase (HN), nuclear protein, or the fusion protein of Sendai virus, the majority of the virus-specific AFCs in the MLN are specific for HN and secrete IgA.

Animals↗
PubMed1994

The human parainfluenza virus type-1 prototypic strain contains a heat-labile hemagglutinin-neuraminidase protein.

The virus yield of human parainfluenza virus type-1 (hPIV-1) in cultured cells at 38 degrees C is reduced more than 100-fold compared to 34 degrees C, while the virus yield of Sendai virus (SV, Enders strain), a murine parainfluenza virus type-1 with high homology to hPIV-1 was almost equal at both temperatures. To understand the basis for the differences in the temperature growth characteristics of the two viruses, we examined the heat-stability of hPIV-1 and SV glycoproteins expressed from cDNAs by pulse-chase experiments. The hemagglutinin-neuraminidase (HN) protein of hPIV-1 was stable after a 6-h chase at 34 degrees C, while at 38 degrees C prominent protein degradation was observed starting at 3 h chase and by 6 h HN was reduced by 65%. In contrast, SV HN protein was stable at both 34 and 38 degrees C. The other hPIV-1 glycoprotein, the fusion (F) protein was stable at both temperatures. To identify the amino acids which are responsible for the heat-lability of hPIV-1 HN, mutant HN proteins were constructed by site-directed mutagenesis. Mutant hPIV-1 HN which had substitutions at positions 461 and 462 became heat-stable at 38 degrees C. These data indicate amino acids around 461 are responsible for the heat-lability of the wild type hPIV-1 HN protein and the reduced yield of the virus at 38 degrees C.

Amino Acid Sequence↗
PubMed1994

Epstein-Barr virus lytic cycle spreads via cell fusion in a nasopharyngeal carcinoma hybrid cell line.

NPC-KT cl.S61, a subclone derived from an epithelial-nasopharyngeal carcinoma hybrid cell line NPC-KT, showed extensive Epstein-Barr virus (EBV) production and cell fusion when the EBV replicative cycle was induced by 5-iodo-2'-deoxyuridine. On the contrary, parental NPC-KT cells produced virus at a lower level and did not show cell fusion. Cell fusion in cl.S61 cells was blocked by 2-deoxyglucose and acyclovir, inhibitors of glycosylation and EBV DNA polymerase, respectively, with a concomitant decrease in the number of cells expressing EBV growth-associated antigens. However, the frequency of virus antigen expression in parental NPC-KT cells was not significantly affected by these drugs. This result suggests that efficient production of EBV from cl.S61 cells is due to the spreading of viral replicative cycle via cell fusion. It was also demonstrated by in situ autoradiography that cl.S61 cells producing virus fused to not only EBV receptor/CR2 positive Raji and BJAB cells, but also to receptor-negative Jurkat cells. The possible mechanism of EBV entry into cells devoid of virus receptor by cell fusion is discussed.

Acyclovir↗
PubMed1994

Morphological aspects of the cytotoxic action of Helicobacter pylori.

OBJECTIVE: To morphologically investigate the cytotoxic action of Helicobacter pylori on gastric mucosal cells. METHODS: Twenty biopsy specimens were obtained from the antrum and greater curvature of the upper body of the stomach, and examined by electron microscopy to elucidate the process of mucus cell injury induced by H. pylori. RESULTS: Only H. pylori colonies in intimate contact with the mucosal cells caused various cell alterations, including loss of microvilli, mucus depletion, cell membrane injury and degeneration of the cytoplasm. In contrast, H. pylori that were not in contact with the mucosa had no effect on the surface mucus cells. CONCLUSIONS: The results of this study suggested the following mechanism of H. pylori-induced gastric mucosal injury. Intimate contact between H. pylori and the epithelial cell is necessary for cytotoxic action. During the process of cytotoxic action, degradation of the mucous gel layer and the glycocalyx are first caused by the proteolytic enzymes produced by H. pylori. Then the microorganism approaches the surface mucus cell, making intimate contact with the cell surface. Finally, H. pylori adheres directly to the cell membrane, effecting direct action of the toxins on the cell membrane. Subsequently, the degenerative changes induced destroy the cell membrane, resulting in degeneration of the cell itself.

Bacterial Adhesion↗
PubMed1994

Relationship between Helicobacter pylori and atrophic gastritis.

OBJECTIVES: To investigate the relationship between Helicobacter pylori and atrophic gastritis. DESIGN AND METHODS: The extent of atrophic gastritis was assessed endoscopically in 97 non-ulcer patients, and their H. pylori status was assessed by enzyme-linked immunosorbent assay. RESULTS: The prevalence of H. pylori infection was greatest in the early stages of atrophic gastritis. Small numbers of H. pylori-negative patients were identified at different stages during the extension of atrophic gastritis. CONCLUSIONS: H. pylori infection precedes the extension of atrophic gastritis, and a minority of patients with atrophic gastritis may never have been infected with H. pylori.

Adolescent↗
PubMed1993

Crystals of hemagglutinin-neuraminidase of parainfluenza virus contain triple-stranded helices.

When purified dimers of hemagglutinin-neuraminidase molecules released by protease digestion from three strains of human parainfluenza virus 1 were used in crystallization trials, long thin needle crystals formed. Electron microscopic analysis of these needle crystals revealed that they are composed of stacks of triple-stranded helices with each strand of the helix made up of subunits of hemagglutinin-neuraminidase. To our knowledge, this is the first direct demonstration of the assembly of protein subunits into large triple-stranded helices. An understanding of the organization of these triple helices may shed light on the structural properties of the hemagglutinin-neuraminidase molecules that cause them to form these helices.

Crystallization↗
PubMed1993

Parapharyngeal abscess associated with the second pharyngeal pouch.

Peritonsillar or parapharyngeal abscess is not at all a rare disease. Usually the abscess is recognized as the underlying consequence of acute tonsillitis. However, the abscess may be caused by an internal fistula related to the second pharyngeal pouch. Presented here are the clinical, radiological and pathological aspects of an internal fistula with a parapharyngeal abscess related to the second pharyngeal pouch.

Abscess↗
PubMed1993

[The effect of the eradication of H. pylori on the intractable ulcer].

On 25 cases (gastric ulcer 14 cases and duodenal ulcer 11 cases) of the intractable ulcer which was H. pylori-positive, we eradicated H. pylori. The eradication was done during 14 days by a triple therapy: bismuth subnitrate 2.0 g, metronidazole 0.75 g, AMPC 0.75 g/day). All cases were confirmed to be eradicated by culture and microscopic examination. 24 cases (gastric ulcer 13/14 and duodenal ulcer 11/11) were confirmed to be completely cured. After the eradication, we ceased the maintenance therapy by H2RA and followed them up, however, no ulcer relapses were found up to 9 months. It was considered that the eradication against H. pylori was a very effective method to the intractable ulcer.

Ampicillin↗
PubMed1992

Crystallization of biologically active hemagglutinin-neuraminidase glycoprotein dimers proteolytically cleaved from human parainfluenza virus type 1.

We isolated, purified, and characterized the hemagglutinin-neuraminidase (HN) of human parainfluenza virus type 1, with the ultimate goal of producing crystals suitable for three-dimensional X-ray structure analysis. Pronase was used to cleave the globular head of the HN molecule directly from virus particles, forming HN monomers and dimers. The purified dimers retained neuraminidase and hemadsorption activity and were recognized by 14 anti-HN monoclonal antibodies, demonstrating intact HN antigenic structure and function. N-terminal sequence analysis of the dimers showed that cleavage had occurred at amino acid 136 or 137, freeing the C-terminal 438 or 439 amino acids. On electron micrography, the dimer appeared as two box-shaped structures, each approximately 5 by 5 nm. When the purified HN dimers were crystallized in hanging drops by vapor diffusion against 20% polyethylene glycol 3350, they formed both rectangular plates and needlelike crystals. The rectangular crystals diffracted X-rays, indicating an ordered atomic structure. However, the resolution was approximately 10 A (1 nm), insufficient for three-dimensional structural analysis. Experiments to improve the resolution by increasing the size and quality of the crystals are in progress.

Amino Acid Sequence↗
PubMed1991

Branchial cleft (pouch) anomalies: a review of 42 cases.

A retrospective review was made of the medical records of 42 patients, who had had branchial cyst, sinus, or fistula, and who had been seen and treated at our hospitals. Three of these lesions were considered to have originated from the first branchial cleft, 36 from the second branchial cleft and/or pouch, and 3 from the fourth branchial pouch. There were no sex and side of presentation differences in the second branchial anomalies. However, the first branchial anomalies occurred predominantly in females, and the fourth branchial anomalies were predominantly left-sided. Pathological findings were of squamous epithelium and subepithelial lymphoid follicles in most branchial remnants. Skin, adenexa, and cartilage were observed in two first branchial cleft sinuses (Work's classification Type II). Columnar epithelium (respiratory type) was observed in a second branchial pouch cyst and a second branchial fistula. All the patients with first or fourth branchial anomalies had previous infections with incision and drainage procedures, whereas only two out of 36 patients with second branchial anomalies had had previous incision procedures. All patients after complete removal of branchial anomalies have no recurrence.

Adolescent↗
PubMed1991

Radiation-induced cranial nerve palsy: hypoglossal nerve and vocal cord palsies.

Cranial nerve palsies are an unexpected complication of radiotherapy for head and neck tumours. We present a case of this radiation-induced cranial palsy. An 18-year-old female with nasopharyngeal carcinoma developed a right hypoglossal nerve palsy 42 months after cancericidal doses of radiotherapy. In addition, she developed a bilateral vocal cord palsy 62 months after therapy. Follow-up over four years has demonstrated no evidence of tumour recurrence and no sign of neurological improvement.

Adolescent↗
PubMed1991

Venous haemangioma of the neck and mediastinum.

A case of cervico-mediastinal venous haemangioma with diffuse upper respiratory airway involvement is reported. The lesion was considered to be an ordinary supraglottic haemangioma at first. We recommend that adult cases of laryngeal haemangioma should be carefully examined for extra-laryngeal lesions.

Bronchoscopy↗
PubMed1991

Focal segmental glomerular hyalinosis and/or sclerosis in rats with congenital unilateral hydronephrosis.

Focal segmental glomerular hyalinosis and/or sclerosis (FSHS) was observed in five Wistar-Imamichi rats with congenital unilateral hydronephrosis (CUH rats). Marked proteinuria (164.9 +/- 138.4 mg/day) was observed in the CUH rats. Immunoperoxidase staining for IgM, C3 and IgG was positive in the glomeruli, showing in a focal, segmental pattern that corresponded to the areas of FSHS seen by light microscopy. These glomerular findings were extremely similar to those of human focal glomerular sclerosis (FGS). FSHS was found to be common to both the hydronephrotic kidney and the contralateral kidney without hydronephrosis. Morphometry revealed that the glomerular area of the juxtamedullary glomeruli was greater than that of superficial glomeruli in control rats (11,037 micron2 vs. 6,847 microns2). On the other hand, glomerular hypertrophy was observed in non-sclerotic glomeruli of CUH rats (superficial glomeruli; 12,477-16,123 microns2, juxtamedullary glomeruli; 14,635-18,418 microns2). Also, a decreased in the number of glomeruli within the range 1.8-4.1 per unit area (1 mm2) was seen in CUH rats compared with control rats (mean 4.4). These results suggest that the increased rate of development of FSHS is based on hyperfiltration in the remaining functional nephrons.

Animals↗
PubMed1991

Changes of anionic sites in the mesangium with aging in rats: a comparison of the immersion and intravenous PEI methods.

We investigated the changes in anionic sites of the mesangial matrix related to aging in rats, employing polyethyleneimine (PEI) as a cationic probe. We compared the numbers of anionic sites detected by the immersion method and by the intravenous administration of PEI. Analysis of the mean numbers of PEI particles per 0.1 micron2 in the mesangial matrix revealed a significant decrease related to aging. Our results suggested that there was no significant difference in efficacy between the immersion and intravenous methods. Loss of negative charge of the mesangial matrix is believed to promote mesangial dysfunction and the entrapment of macromolecular substances, and so to play an important role in the onset of glomerular sclerosis.

Aging↗
PubMed1990

Metabolic basis for differential glutamine requirements of human leukemia cell lines.

We compared the ability of human leukemia cell lines of various origins to grow in glutamine-deficient media. The growth of B lymphoblastoid cell lines, including promyelocytic HL-60, is highly dependent on glutamine, whereas T-cell lines are able to proliferate in glutamine-free media. Such glutamine dependency has a good inverse correlation with the activity of glutamine synthetase. Moreover, glutamine synthetase can be induced in glutamine-deficient media, especially in glutamine-independent cells. In HL-60 cells, glutamine deprivation results in the decrease of both ATP and dATP levels. The addition of adenine to the culture medium abolishes these changes without restoring cell growth, indicating that the effects of glutamine deprivation on cell growth cannot be fully explained by the perturbation of adenine nucleotide pools.

Adenine↗
PubMed1990

Biochemical basis of the prevention of 6-thiopurine toxicity by the nucleobases, hypoxanthine and adenine.

Co-incubation of human leukemia cell lines with naturally occurring nucleobases (hypoxanthine or adenine) significantly prevented the cytotoxic activity of 6-thiopurines. Extracellular hypoxanthine decreased the transport of 6-mercaptopurine into cells, but adenine had no significant effect. However, intracellular thioinosine monophosphate accumulation in the presence of 10 microM, 6-mercaptopurine was reduced to below 1% or 10% of that of the controls when 50 microM hypoxanthine or adenine was added, respectively. Finally, in adenine phosphoribosyl transferase deficient mutants, adenine provided no protective effect against 6-thiopurines, whereas hypoxanthine retained its modulating activity. These data suggest that the nucleobases compete with 6-thiopurines for the ribose-phosphate donor, 5'-phosphoribosyl-1-pyrophosphate, thus preventing the formation of active metabolites of 6-thiopurines.

2-Aminopurine↗
PubMed1990

Cell type dependent activation of poly (ADP-ribose) synthesis following treatment with etoposide.

Treatment of human non-lymphoid cell lines, HL-60 and U937, with etoposide stimulated poly (ADP-ribose) synthesis three- to fourfold, whereas no significant effects were observed in the lymphoid cell lines, Molt4 and CEM. This was confirmed by either an increased uptake of radio-labelled NAD into the acid-insoluble fraction or a fall in cellular NAD levels, which was counteracted by 3-aminobenzamide, an inhibitor of poly(ADP-ribose) polymerase. On the other hand, another DNA damaging agent, N-methyl-N'-nitro-N-nitrosoguanidine augmented poly(ADP-ribose) synthesis equally in both cell types. These results taken together indicate that the activation of poly(ADP-ribose) synthesis following exposure to etoposide is a cell type specific phenomenon.

Cell Survival↗