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Biomedical subjects

H Sato

Publications and source records attributed to H Sato.

At least 559 records · Page 31Linked to original sources
PubMed1999

Kinetics of interactions of sendai virus envelope glycoproteins, F and HN, with endoplasmic reticulum-resident molecular chaperones, BiP, calnexin, and calreticulin.

Sendai virus envelope glycoproteins, F and HN, mature during their transport through the endoplasmic reticulum (ER) and Golgi complex. To better understand their maturation processes in the ER, we investigated the time course of their interactions with three ER- resident molecular chaperones, BiP, calnexin (CNX), and calreticulin (CRT), in Sendai virus-infected HeLa cells. Pulse-chase and immunoprecipitation analyses using antibodies against each virus glycoprotein or ER chaperone revealed that F precursor interacted with CNX transiently (t(1/2)=8 min), while HN protein displayed longer and sequential interactions with BiP (t(1/2)=8 min), CNX (t(1/2)=15 min), and CRT (t(1/2)=20 min). HN interacted with the three ER chaperones not only as a monomer but also as a tetramer for several hours, suggesting mechanism(s) to undergo chaperone-mediated quality control of an assembled HN oligomer in the ER. The kinetics of dissociation of the HN-chaperone complexes exhibited a marked delay in the presence of proteasome inhibitors, suggesting that a part of HN associated with BiP, CNX, and CRT is destined to be degraded in the proteasome-dependent pathway. Further, the associations between virus glycoproteins and CNX or CRT were impaired by castanospermine, an inhibitor of ER glucosidase I and II, confirming that these interactions require monoglucosylated oligosaccharide on F(0) and HN peptides. These findings together suggest that newly synthesized F protein undergoes rapid maturation in the ER through a transient interaction with CNX, whereas HN protein requires more complex processes involving prolonged association with BiP, CNX, and CRT for its quality control in the ER.

Calcium-Binding Proteins↗
PubMed1999

Ets-1 positively regulates expression of urokinase-type plasminogen activator (uPA) and invasiveness of astrocytic tumors.

Acquisition of invasive/metastatic potential through protease expression is an essential event in tumor progression. Urokinase-type plasminogen activator (uPA) is often expressed in human tumors including astrocytic tumors. To elucidate the possible regulation mechanism of uPA gene expression in astrocytic tumors, quantitative RT-PCR was performed to monitor the gene expression of uPA and the transcription factor Ets-1. Expression of uPA and Ets-1 genes was up-regulated in astrocytic tumors, but was not detected in normal brain. Expression levels of uPA correlated with those of Ets-1, and also with the degree of malignancy of the tumors. Glioma cell lines U251, U87, and T98G also expressed both uPA and Ets-1 genes. Expression of a dominant negative mutant of Ets-1, which competitively inhibits Ets-1 function, abolished uPA expression in U251 cells. Parental U251 cells showed invasive growth in 3-dimensional collagen gel, however, cells expressing dominant negative Ets-1 failed to grow invasively in the collagen gel. Treatment of U251 cells with the uPA inhibitor aprotinin also inhibited spreading of cells into collagen gel. These results suggest that Ets-1 plays an essential role in regulation of uPA gene expression, which in turn contributes to the invasive growth of astrocytic tumors.

Brain Neoplasms↗
PubMed1999

Expression of messenger RNAs for membrane-type 1, 2, and 3 matrix metalloproteinases in human renal cell carcinomas.

PURPOSE: Three different membrane-type matrix metalloproteinases (MT1, 2, and 3-MMP) that can activate proMMP-2 (progelatinase A) are thought to play an important role in invasion and metastasis by various human carcinomas. To further clarify this role, we examined mRNA expression of MT-MMPs in human renal cell carcinomas. MATERIALS AND METHODS: mRNA was extracted from 25 clinical specimens of renal cell carcinoma and 23 specimens of normal renal parenchyma remote from the tumor. Reverse transcription polymerase chain reaction (RT-PCR) using specific primers was performed, and PCR products were hybridized to 32P-labeled internal probes and analyzed by a bioimage analyzer. RESULTS: MT1, 2, and 3-MMP mRNA expression in carcinomas was significantly higher than in normal parenchyma. In terms of the pathologic stage, MT1-MMP mRNA expression in pT2 and pT3 tumors was significantly higher than those in pT1 tumors. Although the sample size was small, it was evident that MT3-MMP mRNA expression in clear cell subtype renal cell carcinomas was higher than in the group of tumors including the granular cell subtype. CONCLUSIONS: These three MT-MMPs may play an important role in the pathogenesis of human renal cell carcinoma, and MT1-MMP in particular is important in invasion by carcinoma cells. It is interesting that the expression of MT3-MMP was higher in carcinomas, especially clear cell carcinoma, than in normal parenchyma, so that MT3-MMP may provide a clue an understanding of the molecular mechanism of carcinogenesis in human kidney.

Carcinoma, Renal Cell↗
PubMed1999

Specific lipid-protein interactions in a novel honeycomb lattice structure of bacteriorhodopsin.

In the purple membrane of Halobacterium salinarium, bacteriorhodopsin trimers are arranged in a hexagonal lattice. When purple membrane sheets are incubated at high temperature with neutral detergent, membrane vesicularization takes place, yielding inside-out vesicles with a diameter of 50 nm. The vesicular structure becomes unstable at low temperature, where successive fusion of the vesicles yields a crystal which is composed of stacked planar membranes. X-ray crystallographic analysis reveals that the bacteriorhodopsin trimers are arranged in a honeycomb lattice in each membrane layer and that neighbouring membranes orient in opposite directions. The native structure of the trimeric unit is preserved in the honeycomb lattice, irrespective of alterations in the in-plane orientation of the trimer. One phospholipid tightly bound to a crevice between monomers in the trimeric unit is suggested to act as a glue in the formation of the trimer.

Bacteriorhodopsins↗
PubMed1999

Isolation and purification of a protective protein antigen of Erysipelothrix rhusiopathiae.

The rapid growth and high survival rate of Erysipelothrix rhusiopathiae was determined using a culture of the bacterium in tryptic soy broth supplemented with 0.3% Tris-hydroxymethyl aminomethane and 0.1% Tween 80 (TT-TS broth). High concentrations of 64, 66 and 43 kDa proteins, which are associated with protection against E. rhusiopathiae infection in mice, were obtained by alkaline treatment of whole cells using 0.05-1 N NaOH. The supernatant of alkaline treated cells (alkaline extract; AE) was stable at alkaline or neutral pH. However, aggregates appeared at neutral pH in the absence of sodium dodecyl sulphate (SDS). A high yield of 64, 66 and 43 kDa proteins was obtained from strain Agata (serovar 5). The proteins were eluted from gel bands following SDS-polyacrylamide gel electrophoresis (SDS-PAGE) of the AE from strain Agata and designated P64 and P43. The amounts of P64 and P43 isolated were 0.7 and 0.3 mg/16 g of wet bacteria, respectively. In a mouse protection test, 50% protective doses (PD50) of P64 and P43 were 0.58 and 0.63 microgram, respectively. Upon Western blotting of the AE, both anti-P64 and anti-P43 antibodies reacted with the 64 and 43 kDa proteins. From these results, it is suggested that P64 is the most effective protective antigen and that P43 (43 kDa protein) is a degradation product of P64. Therefore, the 64 kDa structural proteins are associated with the induction of a protective activity against E. rhusiopathiae infection in mice.

Animals↗
PubMed1999

Preparation and partial characterization of monoclonal antibodies against the protective protein antigen of Erysipelothrix rhusiopathiae.

Thirteen mouse monoclonal antibodies (Mabs) against the protective protein antigen (P64) of Erysipelothrix rhusiopathiae were prepared and partially characterized. The titres of the Mabs varied from 200 to 1,638,400 as determined by enzyme-linked immunosorbent assay (ELISA). Of the 13 Mabs 10, two and one belonged to the IgG2a, IgG1 and IgM subclasses, respectively. All Mabs reacted strongly with the 64 kDa protein and weakly with the 43 kDa protein upon Western blotting of the alkaline extract (AE) of E. rhusiopathiae. The protective activity (PD50/ml) of the 13 Mabs against E. rhusiopathiae infection in mice varied from < 50 to > 50,000. These Mabs were classified into three groups, highly protective Mabs, moderately protective Mabs and Mabs which did not possess protective activity, based on the protective index (ratio of the PD50/ml to the antibody titre). These results suggest that the 64 kDa protein is an effective protective antigen, which is easily cleaved into many small proteins, including the 43 kDa protein, and possesses at least two epitopes related to its protective activity and at least one epitope which is not related to protection of mice against E. rhusiopathiae infection.

Animals↗
PubMed1999

Chronic active desease refext cancer riski in ulcreative collitis.

There is an increased risk of developing colorectal neoplasia in ulcerative colitis (UC) and surveillance colonoscopy is recommended for early detection. We investigated the precise features of UC retrospectively to identify a subgroup with longstanding extensive UC at increased risk of neoplasia. From 1985 to August 1997, we experienced eight UC patients with colorectal cancer and eight with definite dysplasia. All 16 had extensive disease of seven years or more in duration. During the same period, 61 of 334 UC patients without colorectal neoplasia were available for detailed study, allowing evaluation of non-surgical patients with extensive colitis of seven years or more in duration. Basic clinical factors including family history of cancer, expressions of disease activity and durations of pharmacotherapy were investigated. Univariate analysis revealed four significant factors: intractability (P=0.001), periods of inflammation persisting for 3 months or more (P<0.01) and total durations of diarrhea (P<0.01) and hematochezia (P<0.05). The number of admissions and the duration of systemic steroid administration were higher in the neoplasia group but without statistical significance. Multivariate analysis revealed two significant factors: duration of diarrhea (P<0.001) and age at onset (P<0.01). Chronic active disease is a risk factor for colorectal cancer or dysplasia in extensive and longstanding UC.

Adult↗
PubMed1999

Effects of a soybean isoflavone mixture on carcinogenesis in prostate and seminal vesicles of F344 rats.

Several epidemiological studies have suggested an inverse association between the risk of prostate cancer and intake of soybeans and their products. In vitro data pointing to possible anti-carcinogenic properties of the soybean isoflavone, genistein, led us to investigate the chemopreventive potential of soybean isoflavones in a rat carcinogenesis model induced by 3,2'-dimethyl-4-aminobiphenyl (DMAB) and testosterone propionate (TP). Animals received DMAB s.c. injections at 2-week intervals for the first 20 weeks and implanted silicon tubes containing 40 mg of TP, replaced at 6-week intervals throughout the experiment. The soybean isoflavone mixture consisting of 74% genistein and 21% daidzein was mixed in basal diet (AIN-76A) at concentrations of 100 and 400 ppm and fed to F344 male rats throughout the experiment. Rats treated with carcinogens and administered isoflavone mixture at 100 and 400 ppm developed adenocarcinomas at incidences of 35% and 29%, respectively, in the prostate and seminal vesicles, whereas the figure was 60% for those maintained on control diet. Feeding of the isoflavone mixture at 100 and 400 ppm significantly inhibited the number of argyrophilic nucleolar organizer regions (AgNORs) in adenocarcinomas of the accessory sex glands as compared to those of rats fed control diet. No influence on the development of neoplastic lesions originating in other organs was noted. The results of this study provide evidence that soybean isoflavones may have potential as chemopreventive agents against carcinogenesis in the prostate.

Aminobiphenyl Compounds↗
PubMed1999

Shedding of membrane type 1 matrix metalloproteinase in a human breast carcinoma cell line.

Membrane type 1 matrix metalloproteinase (MT1-MMP) with a transmembrane domain is a new member of the MMP gene family and is expressed on the cell surfaces of many carcinoma cells to activate the zymogen of MMP-2 (gelatinase A). We have previously reported that MT1-MMP is released into culture media in a complex form with tissue inhibitor of metalloproteinases 2 (TIMP-2) from a human breast carcinoma cell line, MDA-MB-231, treated with concanavalin A (Con A). In the present study, we further studied the release mechanism of MT1-MMP. Immunoblot analysis indicated that the amounts of MT1-MMP in culture media increase with the time of exposure and the concentration of Con A, and those in cell lysates conversely decrease in a similar way. Time- and dose-dependent release of MT1-MMP into the media was confirmed by a sandwich enzyme immunoassay specific to MT1-MMP. The molecular weight of the immunoreactive MTI-MMP in the media was Mr 56,000, which was 4,000-Mr smaller than that in the cell lysates. Northern blot analysis demonstrated that the mRNA expression level of MT1-MMP is about 3-fold enhanced after a 24 h-exposure to Con A and this is maintained up to 72-h exposure. The release of MT1-MMP from the Con A-treated cells was inhibited by metalloproteinase inhibitors such as EDTA and o-phenanthroline, but not by MMP inhibitors including TIMP-1, TIMP-2 and BB94 or other proteinase inhibitors of serine, cysteine and aspartic proteinases. During the Con A treatment of the cells, cell viability decreased time- and dose-dependently and dead cells reacted positively in the TdT-mediated dUTP Nick-End Labeling (TUNEL) method. Con A-treated MDA cells showed apoptotic morphology when stained with Hoechst dye and hematoxylin and eosin. DNA ladder formation was detected by electrophoresis of the DNA from Con A-treated MDA cells. These results suggest that MT1-MMP release from Con A-treated cells is due to shedding mediated by metalloproteinase(s) other than MMPs, and is associated with apoptosis.

Apoptosis↗
PubMed1999

[Epidemiological characteristics and virulence factor of verotoxin-producing Eschericia coli O121:H19 isolated in Akita Prefecture in July 1997].

Epidemiological characteristics and virulence factors of VTEC O121:H19 strains isolated in July 1997 from a 15 year old female and a 20 year old male patient suffering from bloody diarrhea and severe abdominal pain were examined. The 2 VTEC O121:H19 isolates showed identical antibiotic susceptibility patterns, biochemical characteristics and plasmid profile while slight differences were observed in their Xba I and Not I PFGE patterns, suggesting that closely related 2 VTEC O121:H19 strains evoked the sporadic infectious cases in July 1997. The 2 VTEC O121:H19 isolates, as well as VTEC O157:H7, possessed eaeA gene and a ca. 60 MDa plasmid which hybridised with CVD 419 probe and produced enterohemolysin. In addition, the VTEC O121:H19 isolates produced almost the same amount of VT-2 in vitro as VTEC O157:H7 did. These results suggested that VTEC O121:H19 possesed the virulence factor comparable to that of VTEC O157:H7. Incidence, molecular epidemiology and infectious source of VTEC O121:H19 in this country have not been sufficiently understood. Antiserum for E. coli serogroup O121 should be manufactured to clarify the epidemiology of the highly virulent VTEC strain.

Adolescent↗
PubMed1999

New exfoliative toxin produced by a plasmid-carrying strain of Staphylococcus hyicus.

A new serotype of Staphylococcus hyicus exfoliative toxin (SHET), serotype B, was isolated from the culture filtrate of a plasmid-carrying strain of S. hyicus. The new SHET was purified by precipitation with 70% saturated ammonium sulfate, gel filtration on a Sephadex G-75 column, column chromatography on DEAE-Cellulofine A-500, and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The new SHET caused exfoliation of the epidermis as determined by the so-called Nikolsky sign when inoculated into 1-day-old chickens. The new SHET was serologically different from Staphylococcus aureus exfoliative toxins (ETs) (ETA, ETB, and ETC) and from the SHET from the plasmidless strain but showed the same molecular weight as the other serotypes of toxins on SDS-PAGE. It was thermolabile and lost its toxicity after being heated at 60 degrees C for 30 min. We propose that the new SHET be designated SHETB and that the SHET produced by the plasmidless strain be designated SHETA.

Animals↗
PubMed1999

Evolution and biological characterization of human immunodeficiency virus type 1 subtype E gp120 V3 sequences following horizontal and vertical virus transmission in a single family.

It has been suggested that immune-pressure-mediated positive selection operates to maintain the antigenic polymorphism on the third variable (V3) loop of the gp120 of human immunodeficiency virus type 1 (HIV-1). Here we present evidence, on the basis of sequencing 147 independently cloned env C2/V3 segments from a single family (father, mother, and their child), that the intensity of positive selection is related to the V3 lineage. Phylogenetic analysis and amino acid comparison of env C2/V3 and gag p17/24 regions indicated that a single HIV-1 subtype E source had infected the family. The analyses of unique env C2/V3 clones revealed that two V3 lineage groups had evolved in the parents. Group 1 was maintained with low variation in all three family members regardless of the clinical state or the length of infection, whereas group 2 was only present in symptomatic individuals and was more positively charged and diverse than group 1. Only virus isolates carrying the group 2 V3 sequences infected and induced syncytia in MT2 cells, a transformed CD4(+)-T-cell line. A statistically significant excess of nonsynonymous substitutions versus synonymous substitutions was demonstrated only for the group 2 V3 region. The data suggest that HIV-1 variants, possessing the more homogeneous group 1 V3 element and exhibiting the non-syncytium-inducing phenotype, persist in infected individuals independent of clinical status and appear to be more resistant to positive selection pressure.

Amino Acid Sequence↗
PubMed1999

Role of naturally occurring basic amino acid substitutions in the human immunodeficiency virus type 1 subtype E envelope V3 loop on viral coreceptor usage and cell tropism.

To assess the role of naturally occurring basic amino acid substitutions in the V3 loop of human immunodeficiency virus type 1 (HIV-1) subtype E on viral coreceptor usage and cell tropism, we have constructed a panel of chimeric viruses with mutant V3 loops of HIV-1 subtype E in the genetic background of HIV-1LAI. The arginine substitutions naturally occurring at positions 8, 11, and 18 of the V3 loop in an HIV-1 subtype E X4 strain were systematically introduced into that of an R5 strain to generate a series of V3 loop mutant chimera. These chimeric viruses were employed in virus infectivity assays using HOS-CD4 cells expressing either CCR5 or CXCR4, peripheral blood mononuclear cells, T-cell lines, or macrophages. The arginine substitution at position 11 of the V3 loop uniformly caused the loss of infectivity in HOS-CD4-CCR5 cells, indicating that position 11 is critical for utilization of CCR5. CXCR4 usage was conferred by a minimum of two arginine substitutions, regardless of combination, whereas arginine substitutions at position 8 and 11 were required for T-cell line tropism. Nonetheless, macrophage tropism was not conferred by the V3 loop of subtype E R5 strain per se. We found that the specific combinations of amino acid changes in HIV-1 subtype E env V3 loop are critical for determining viral coreceptor usage and cell tropism. However, the ability to infect HOS-CD4 cells through either CXCR4 or CCR5 is not necessarily correlated with T-cell or macrophage tropism, suggesting that cellular tropism is not dictated solely by viral coreceptor utilization.

Amino Acid Sequence↗
PubMed1999

Matrix metalloproteinase 9 expression is induced by Epstein-Barr virus latent membrane protein 1 C-terminal activation regions 1 and 2.

Nasopharyngeal carcinoma (NPC), which is closely associated with the Epstein-Barr virus (EBV), is a highly metastatic malignant tumor. An important activity in tumor invasion and metastasis is that of the 92-kDa type IV collagenase or gelatinase, matrix metalloproteinase 9 (MMP-9), which mediates the degradation of the basement membrane and extracellular matrix. The expression of MMP-9 has been shown to be enhanced by the EBV oncoprotein, latent membrane protein 1 (LMP-1). LMP-1, which is expressed in NPC, has two essential signaling domains within the carboxy terminus, termed C-terminal activation regions 1 (CTAR-1) and CTAR-2. This study reveals that either signaling domain can activate the MMP-9 promoter and induce MMP-9 activity; however, LMP-1 deletion mutants lacking either CTAR-1 or CTAR-2 had a decreased ability to induce MMP-9 expression. The deletion of both activation regions completely abolished the induction of MMP-9 activity, while the cotransfection of both the CTAR-1 and CTAR-2 deletion mutants restored MMP-9 activity to levels produced by wild-type LMP-1. The NF-kappaB and activator protein 1 (AP-1) binding sites in the MMP-9 promoter were essential for the activation of MMP-9 gene expression by both CTAR-1 and CTAR-2. The induction of MMP-9 expression by LMP-1 and both CTAR-1 and CTAR-2 mutants was blocked by the overexpression of IkappaB. The tumor necrosis factor receptor-associated factor (TRAF) pathway also contributed to the activation of the MMP-9 promoter as shown by the use of TRAF-2 and TRAF-3 dominant-negative constructs. These data indicate that the activation of both the NF-kappaB and AP-1 pathways by LMP-1, CTAR-1, and CTAR-2 is necessary for the activation of MMP-9 expression. In NPC, LMP-1 may contribute to invasiveness and metastasis through the induction of MMP-9 transcription and enzymatic activity.

Binding Sites↗
PubMed1999

Giant aneurysm of the left main coronary artery in Takayasu aortitis.

Takayasu aortitis is a chronic inflammatory vasculitis characterised by stenosis or obliteration of large and medium sized arteries. Although coronary arteries are affected in approximately 10% of cases, most of the lesions are luminal narrowing, and coronary aneurysm formation is extremely rare. A case is described of giant aneurysm of the left main coronary artery complicated with Takayasu aortitis in a 46 year old Japanese woman who was followed until her death at age 71. Pronounced intimal proliferation and adventitial fibrous thickening of the involved arterial wall usually induce constriction or occlusion at the orifice of the main branch of the aorta in Takayasu aortitis. However, systemic hypertension, which resulted from renovascular stenoses in this case, is likely to have enlarged the vessel lumen before replacement of medial and adventitial fibrosis after extensive destruction of medial elastic fibres in the left main coronary artery. Moreover, associations such as autoimmune hepatitis, chronic thyroiditis, and Sjögren syndrome strongly suggests that Takayasu aortitis may be an autoimmune disease.

Aorta↗
PubMed1999

Incorporation of dietary docosahexaenoic acid into the central nervous system of the yellowtail Seriola quinqueradiata.

In order to show the involvement of docosahexaenoic acid (DHA) in the development of the central nervous system (CNS) in carangid fish, we conducted tracer experiments by feeding radioactive DHA to larval yellowtail (Seriola quinqueradiata). Artemia nauplii were enriched with 14C-labeled DHA and fed to larval yellowtail for eight or ten days. Autoradiography of frozen sections, using both electric imaging plates and X-ray sensitive film, clearly showed that DHA was incorporated into and retained in the brain, spinal cord, and eyes. The brain, eyes, gill raker, liver, guts, and other muscle and bone structures were dissected, and radioactivity was measured in each organ by liquid scintillation counter. The results of this study suggest the incorporation of DHA into the brain. Considering our previous results indicating that DHA-free fish cannot form schools, we conclude that the incorporation of DHA into the brain might be a critical factor in the ontogeny of schooling behavior.

Animals↗
PubMed1999

Expression of CA125 in thoracic endometriosis in a patient with catamenial pneumothorax.

A 40-year-old woman had experienced monthly right thoracic pain and productive cough occurring at the beginning of her menstrual period. X-ray findings indicated a diagnosis of catamenial pneumothorax. The serum CA125 level was very high at 159.6 U/ml. Thoracoscopy showed multiple dark cherry-colored nodules with neovascularization on the diaphragm. Following partial resection of the diaphragm thoracic endometriosis was diagnosed. Immunohistochemical staining of these endometrial cells showed antibodies to CA125. She has been well without recurrence for 15 months, and her serum CA125 level was within the normal range after operation.

Adult↗