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N Yokoyama

Publications and source records attributed to N Yokoyama.

At least 19 recordsLinked to original sources
PubMed1998

Significance of development of late potentials after anterior wall acute myocardial infarction despite successful primary angioplasty of the left anterior descending coronary artery.

We classified 33 patients with a first anterior infarction and single-vessel disease who had undergone successful primary angioplasty and had a patent infarct-related artery into groups based on the development of late potentials. Left ventricular function improved between 1 and 3 months after angioplasty only in patients without late potentials; the development of late potentials after acute anterior infarction was associated with prolonged left ventricular dysfunction despite successful revascularization with primary angioplasty.

Aged↗
PubMed1998

In vitro recombination of feline herpesvirus type 1.

We investigated the possibility of in vitro recombination of three different strains of feline herpesvirus type 1 (FHV-1), a virulent strain (C7805), a vaccine strain (F2), and a candidate vaccine strain with a deletion in the thymidine kinase gene (C7301dlTK). The results showed that recombination within different genotypes of FHV-1 strains could occur at a relatively high frequency ranging from 10.1% to 21.5% in vitro. These results indicate the generation of multiple mutant viruses by in vitro recombination experiments. The possibility for generating a virulent virus or novel type of FHV-1 by recombination in vivo is discussed.

Animals↗
PubMed1998

Construction of a recombinant feline herpesvirus type 1 expressing Gag precursor protein of feline immunodeficiency virus.

We constructed a deletion mutant of feline herpesvirus type 1 (FHV-1) and a recombinant FHV-1. The deletion mutant is the virus with a region (367 bp) deleted from the start codon of thymidine kinase (TK) gene to the SmaI site within the TK gene, and the other is a recombinant FHV-1 expressing Gag protein of feline immunodeficiency virus (FIV), in which a cDNA encoding the Gag protein of FIV was inserted at the TK deletion site of the former deletion mutant. These viruses were designated as C7301ddlTK and C7301ddlTK-gag, respectively. Growth kinetics of these viruses in Crandell feline kidney cells was similar to that of the parent C7301 strain. By immunoblot analysis, C7301 ddlTK-gag was confirmed to express the FIV Gag precursor protein in the cells.

Alphaherpesvirinae↗
PubMed1998

Genetic deficiency of angiotensinogen produces an impaired urine concentrating ability in mice.

Angiotensinogen gene-knockout (Atg-/-) mice lacking angiotensin II exhibit chronic hypotension. The present study was designed to investigate pathophysiology of Atg-/- mice from the renal functional view. Wild-type (Atg+/+) and Atg-/- mice at 10 weeks of age were housed in metabolic cages for 24-hour urine collection. When provided free access to water, Atg-/- mice showed an increased urine output and a decreased urine osmolality compared with Atg+/+ mice. Urinary excretion and plasma levels of vasopressin were significantly higher in mutant mice than in wild-type mice. On the other hand, urinary excretion of aldosterone in mutant mice was suppressed to the levels under the detection limit of the assay system. The mean plasma aldosterone level of Atg-/- mice was suppressed to 30% of that of Atg+/+ mice. Plasma levels of creatinine, endogenous creatinine clearance, and urinary electrolyte excretion were not different between these mice. In Atg+/+ mice, urine osmolality was markedly increased from 1929 +/- 21 to 3314 +/- 402 mOsm/kg during water deprivation, whereas this parameter in Atg-/- mice did not change significantly (from 1413 +/- 121 to 1590 +/- 92 mOsm/kg). Urinary vasopressin excretion increased during water deprivation from 0.24 +/- 0.04 and 0.70 +/- 0.08 to 0.42 +/- 0.06 and 2.31 +/- 0.35 ng/mg creatinine in wild-type and mutant mice, respectively. Histologic study revealed interstitial inflammation, and atrophic changes in the tubules and papilla in Atg-/- mice. In conclusion, a genetic deficiency of angiotensinogen produced an impaired urine concentrating ability and tubulointerstitial lesions, indicating the critical role of angiotensinogen in developing normal tubular function and construction.

Aldosterone↗
PubMed1998

Overexpression, purification and helix-destabilizing properties of Epstein-Barr virus ssDNA-binding protein.

The Epstein-Barr virus (EBV) ssDNA-binding protein (SSB) encoded by the BALF2 gene is one of the essential replication proteins in the lytic phase of EBV DNA replication. In order to obtain the amount of EBV SSB required for characterization, a recombinant baculovirus containing the complete sequence of the BALF2 open reading frame under the control of the baculovirus polyhedrin promoter was constructed. Insect cells infected with the recombinant virus produced a protein of 130 kDa, recognized by anti-BALF2 protein-specific polyclonal antibody. The overexpressed EBV SSB was purified homogeneously from the cytosolic fraction of the recombinant virus-infected cells. The purified protein displaced short DNA strands from their complementary sequences in the single-stranded form of M13. The helix-destabilizing activity was neutralized by the anti-BALF2 protein-specific antibody. Maximum unwinding occurred at EBV SSB concentrations exceeding saturation level of the DNA substrate. The DNA unwinding reaction mediated by the EBV SSB was highly cooperative and extremely rapid. The reaction displayed no directionality and required neither ATP nor MgCl2, two essential cofactors for DNA helicase activity. The helix-destabilizing property of the EBV SSB may function to melt out secondary structures on the ssDNA template, thereby facilitating the movement of the EBV DNA polymerase.

Animals↗
PubMed1998

Role of apoptosis of thyrocytes in a rat model of goiter. A possible involvement of Fas system.

Apoptosis, a physiological process of cell death, may modulate the mass of the thyroid gland. We investigated the role of apoptosis and the possible involvement of Fas/Fas ligand (FasL) system in apoptosis during goiter formation and involution in a rat model of goiter. Rats were fed a low iodine diet and a goitrogen, 6-propyl-2-thiouracil, to induce goiter. Rats with goiter were then fed a high iodine diet to study the phase of involution. We examined the presence of apoptosis by electron microscopy (EM) and terminal deoxy-UTP nick end labeling (TUNEL). We also investigated the association between Fas and FasL expression and thyrocyte apoptosis using immunohistochemistry and Western blotting. To evaluate the proliferation of thyrocytes, proliferating cell nuclear antigen was examined immunohistochemically. The number of apoptotic cells increased during goiter formation and the early stage of involution, which were also associated with increased number of Fas-positive thyrocytes, and some of these cells contained TUNEL-positive nuclei. However, the expression of FasL was almost constant throughout the experiment. Proliferating cell nuclear antigen/TUNEL ratio markedly increased during goiter formation but decreased particularly during the late stage of goiter involution. Our results indicate that apoptosis of thyrocytes is a main factor of cell loss during goiter formation and involution and suggest that the Fas/FasL system is involved in the induction of apoptosis of these cells. Moreover, the delicate balance between apoptosis and cell proliferation may play an important role in the control of thyroid gland mass.

Animals↗
PubMed1998

Nucleotide sequences of glycoprotein I and E genes of equine herpesvirus type 4.

The nucleotide sequences of the glycoprotein I (gI) and E (gE) genes of equine herpesvirus type 4 (EHV-4) strain TH20 were determined. The predicted region encoding the EHV-4 gI gene is 1,263 nucleotides, corresponding to a polypeptide of 420 amino acids in length. The predicted region encoding the EHV-4 gE gene is 1,647 nucleotides, corresponding to a polypeptide of 548 amino acids in length. The EHV-4 gI and gE genes show 74% and 85% identity at the amino acid level with those of equine herpesvirus type 1 (EHV-1), respectively. Furthermore, we have found an open reading frame homologous to the EHV-1 gene 75, which overlaps in part with the 3' end of EHV-4 gE gene. These sequence data will be useful for development of a modified live vaccine against equine herpesvirus type 1 and 4 infections.

Amino Acid Sequence↗
PubMed1998

Further development of a recombinant feline herpesvirus type 1 vector expressing feline calicivirus immunogenic antigen.

We previously reported the attenuation of thymidine kinase (TK) deficient mutant (C7301dlTK) of feline herpesvirus type 1 (FHV-1) in cats and the construction of a recombinant FHV-1 (C7301dlTK-Cap) inserted a precursor capsid gene of feline calcivirus (FCV) into the TK deletion locus of the C7301dlTK. In this study, we constructed a further improved recombinant FHV-1 (dlTK(gCp)-Cap) carrying a putative FHV-1 gC promoter sequence upstream of the FCV precursor capsid gene of the C7301dlTK-Cap. Growth kinetics of the dlTK(gCp)-Cap in cell cultures was similar to those of C7301dlTK and C7301dlTK-Cap. A strong expression of FCV immunogenic antigen by dlTK(gCp)-Cap was confirmed by indirect immunofluorescence and enzyme-linked immunosorbent assays. In addition, one vaccination with dlTK(gCp)-Cap protected cats more effective against subsequent virulent FCV challenge than that with C7301dlTK-Cap.

Animals↗
PubMed1998

Mutations of p53 in gallbladder carcinomas in high-incidence areas of Japan and Chile.

Gallbladder adenocarcinomas from patients in two high-prevalence areas, Niigata (Japan) and Santiago (Chile), were analyzed for acquired mutations in exons 5-8 of the p53 tumor suppressor gene, and the characteristics of p53 alterations in the two groups were compared. Of 42 tumors, 22 (52.4%) harbored 25 alterations identified by PCR amplification and direct sequencing (13 of 22 tumors from Niigata and 12 of 20 tumors from Santiago). All alterations were single base pair substitutions, 20 (80%) leading to an amino acid substitution or a chain-termination signal, and 5 (20%) were silent. Immunohistochemically, 55 of 84 cases (65.5%) showed overexpression of p53 protein, with no significant difference in frequency between the two areas. Missense mutations correlated highly with overexpression of the p53 protein (93.4%). Mutations of p53 occurred in all four exons examined, most commonly in exon 5, but in no particular "hot spot." In base-change spectra, all 12 mutations from Santiago showed transitions, with 4 arising at the CpG dinucleotide (33.3%). In contrast, no such transition was found at CpG sites in Niigata, and 4 of 13 mutations (30.8%) were transversions. The data indicated that p53 mutations are highly important in carcinogenesis in the gallbladder. In addition, the difference in p53 mutational spectra in Niigata and Santiago indicate a likely regional difference in mutagenesis.

Adult↗
PubMed1997

Lymph node spread from carcinoma of the gallbladder.

BACKGROUND: Lymph node spread is the most common pattern of progression in gallbladder carcinoma (GBC) and is a prognostic factor. The purpose of this study was to determine the prevalence of lymph node metastases in patients with resected advanced GBC, and to evaluate the curative effects of radical surgery for patients with lymph node metastasis. METHODS: One hundred and eleven consecutive patients who had undergone radical surgery for GBC were included in this study. The pattern of lymph node metastases was examined histopathologically, using the TNM staging of the American Joint Committee on Cancer. RESULTS: There was no neurovascular invasion or lymph node involvement in 15 patients with pT1 tumors. Sixty of 96 patients with pT2-4 tumors had lymph node metastases. The pericholedochal lymph node was the most common metastatic lymph node, followed by the cystic lymph node. The frequency of metastases in retroportal, posterosuperior pancreaticoduodenal, and interaorticocaval lymph nodes was >15% in all cases. pT3-4 tumors had significantly more lymph node involvement (79%) and significantly higher N2:N1 ratios (2.5) than pT2 tumors (46% and 0.6, respectively). There was no difference in 5-year survival between N0 and N1 groups in pT2-4 tumors (66% in N0 and 53% in N1). Patients with N2 disease had a significantly worse prognosis, but 4 patients survived >5 years. CONCLUSIONS: The cystic and pericholedochal lymph nodes are the initial site of spread from GBC. The frequency of lymph node involvement is strongly influenced by the depth of invasion of the primary tumor. GBC limited to such lymph node metastases can be cured by surgery in >50% of such cases.

Adenocarcinoma↗
PubMed1997

Correlation between overall pesticide effects monitored by shrimp mortality test and change in macrobenthic fauna in a river.

The relationship between change in benthic fauna in the Suna River and shrimp mortality in the river water samples (test was conducted two times per week from May to September) was investigated to assess the insecticide impact on the benthic community. The river was selected because pesticide application had been restricted for a long time in the upper reaches, while aerial insecticide spraying had been done four times on paddy fields in the lower reaches in summer. Species richness and density of benthos were high at the stations in the upper reaches. High shrimp mortality was measured in the water samples collected from a downstream station during the pesticide spraying period, from late July to late August. Species richness and density of benthos markedly decreased at the stations in the lower reaches in that period. However, several species of chironomids, Cheumatopsyche (Trichoptera), which demonstrated tremendous insecticide resistance, and Baetis sahoensis (Ephemeroptera), which has a high recovery potential, were not affected, even in the insecticide spraying period. The benthic fauna in the lower reaches tended to recover from autumn to spring, although not sufficiently. It is considered that the temporal recovery of the benthic community was brought about through recruitment from the benthic community in the 5-km upper reaches. A close correlation was found between the high mortality of shrimp in the water samples and the deterioration in the benthic fauna in this river which was contaminated with insecticides during the summer.

Animals↗
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

Relationship between hepatic angiotensinogen mRNA expression and plasma angiotensinogen in patients with chronic hepatitis.

Recent association and linkage studies suggested that angiotensinogen may play an important role in the pathogenasis of essential hypertension. However, there is little information in human concerning a relationship between plasma angiotensinogen levels and the angiotensinogen mRNA expression in the liver, which is the main production site of angiotensinogen. Therefore, the aim of this study was to examine whether hepatic angiotensinogen gene expression determines the level of circulating angiotensinogen and the activity of the renin-angiotensin system in humans. The subjects were 36 patients with chronic hepatitis. Blood was collected from each patients for estimation of plasma renin activity, plasma angiotensinogen and angiotensin II concentrations and several parameters of liver function. In addition, total RNA was isolated from liver biopsy specimens, which were then used to measure angiotensinogen mRNA with Northern blot analysis. Levels of angiotensinogen mRNA were detected easily in the liver biopsy specimens in all of the patients. Hepatic angiotensinogen mRNA levels were positively correlated with plasma angiotensinogen levels (r=0.41, P=0.013). In contrast, hepatic angiotensinogen mRNA levels did not show any significant relationship with plasma renin activity, plasma angiotensin II concentration, histological subgroup of hepatitis, histological activity index and parameters of liver function tests. The present study demonstrated, for the first time, that hepatic angiotensinogen mRNA levels correlated with plasma angiotensinogen concentration in humans.

Adult↗
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

Identification and characterization of the feline herpesvirus type 1 glycoprotein C gene.

The feline herpesvirus type 1 (FHV-1) gene encoding glycoprotein C (gC) has been sequenced and identified based on its genomic location and comparative analysis to other alphaherpesvirus gCs, and the expressed gC protein was also identified by using specific monoclonal antibodies. The FHV-1 gC gene was located within a 7.0 kbp EcoRI fragment, and was 1602 bp in length. The amino acid sequence deduced from the nucleotide sequence was predicted to encode a membrane glycoprotein containing a characteristic N-terminal hydrophobic signal sequence, nine potential N-linked glycosylation sites, and C-terminal transmembrane and cytoplasmic domains. The FHV-1 gC was expressed in COS-7 cells. When flowcytometric analysis was carried out, the gC expressed in COS-7 cells reacted with a panel of monoclonal antibodies against gp113: By immunoprecipitation analysis, the gC expressed in COS-7 cells possessed molecular masses of 125-150 kilodalton, and was similar in size to that in FHV-1-infected CRFK cells.

Alphaherpesvirinae↗
PubMed1997

Thyroid dysfunction in patients with amyloid goitre.

OBJECTIVES: Widespread amyloid deposition in the thyroid gland causes diffuse, clinically apparent enlargement of the thyroid (amyloid goitre: AG). The aim of this study was to clarify the abnormalities of thyroid function in patients with AG. DESIGN: Thirty patients with secondary amyloidosis were retrospectively analysed. Their thyroid status was evaluated using the results of routine thyroid function tests and measurement of thyroid autoantibodies. Thyroid needle biopsy was carried out to identify amyloid deposition in the thyroid gland. RESULTS: Thyroid enlargement was observed in 19 (63%) of 30 patients with amyloidosis. Eleven of these 19 patients had a thyroid biopsy and/or autopsy and amyloid deposition was histologically revealed in 10 (defined as AG) of these 11 patients. Nine of 10 patients (90%) with AG had abnormalities of thyroid function, including five patients with hypothyroidism, one with hyperthyroidism, one with transient hypothyroidism, and two with low T3 syndrome. Five had thyroid autoantibodies. The patient with hyperthyroidism had positive thyroid stimulating antibody (TSAb) and high 131I thyroidal uptake, suggesting the coexistence of Graves' disease. Another patient suffered from thyroidal pain and showed transient hypothyroidism, high level of serum thyroglobulin and low thyroidal uptake of 123I, the clinical course being compatible with subacute thyroiditis. CONCLUSIONS: The incidence of thyroid abnormalities accompanied by AG, although asymptomatic, is unexpectedly high. Thyroid function should therefore be regularly assessed during follow-up of patients with systemic amyloidosis.

Adult↗