Biomedical subjects

T Yokoi

Publications and source records attributed to T Yokoi.

At least 19 recordsLinked to original sources

PubMed1992

Apoptotic cell death of primed CD45RO+ T lymphocytes in Epstein-Barr virus-induced infectious mononucleosis.

The expansion of activated T cells, characterized by the expression of CD45RO as well as HLA-DR antigens, is a central feature in acute infectious mononucleosis (IM) induced by primary infection of Epstein-Barr virus (EBV). However, the fate of these activated T cells in this disease is not clearly understood. We found that, on simple culture, a large proportion of T cells isolated from acute IM patients died rapidly, but only a few T cells from normal individuals did. Morphologic observations and DNA fragmentation analysis showed that the loss of viability of IM T cells after incubation was mediated by apoptosis. IM T cells undergoing apoptosis resided exclusively in the CD45RO+ populations of both CD4+ and CD8+ T cells, most of which were shown to coexpress apoptosis-related Fas antigen. Some cytokines such as interleukin-2 (IL-2), IL-5, and IL-6 could rescue IM T cells from apoptotic cell death. The results seemed to imply that most of primed (CD45RO+) T cells in acute IM might be subject to apoptotic cell death, possibly when leaving from the local sites actively producing certain soluble factors required for their survival. Our studies suggest the programmed cell death of peripheral mature T cells as a mechanism of antigen-driven selection.

Antigens, CD↗

PubMed1992

Interferon-gamma gene expression in unstimulated bone marrow mononuclear cells predicts a good response to cyclosporine therapy in aplastic anemia.

Cyclosporine (CyA) therapy has been shown to be effective in some patients with aplastic anemia. In an attempt to characterize aplastic patients likely to benefit from CyA therapy, we examined bone marrow mononuclear cells (BMMC) obtained before therapy from 23 patients with aplastic anemia, who were treated with CyA alone. Expression of four myelosuppressive cytokines, including tumor necrosis factor (TNF), lymphotoxin, macrophage inflammatory protein-1 alpha (MIP-1 alpha), and interferon-gamma (IFN-gamma) was examined using polymerase chain reaction (PCR)-assisted messenger RNA (mRNA) amplification. mRNA for TNF, lymphotoxin, and MIP-1 alpha was readily detectable at variable levels in BMMC from normal and transfused controls as well as in BMMC from aplastic patients. In contrast, IFN-gamma mRNA was only demonstrable in BMMC from some patients with aplastic anemia, irrespective of a history of transfusions. Of 13 patients who responded to CyA therapy and achieved transfusion-independence, IFN-gamma mRNA was detected in 12 patients, whereas the mRNA was only detectable in 3 of 10 patients refractory to CyA therapy (P = .003, Fisher's exact test). Follow-up examination of BMMC obtained from seven CyA-responding patients after hematologic remission showed disappearance of IFN-gamma mRNA in four patients. These results suggest that detection of IFN-gamma gene expression in pretreatment BMMC from aplastic patients using PCR may be helpful in predicting a good response to CyA therapy.

Adolescent↗

PubMed1992

Decrease in the content of cytochrome P450IIE by fasting in liver microsomes of house musk shrew (Suncus murinus).

The effects of fasting on hepatic cytochrome P450 in the mature male house musk shrew, Suncus murinus (suncus), were studied by Western blot analyses and enzyme assays. The content of P450IIE protein was decreased, by fasting, to 24% of the control level in contrast to the results with rats, in which P450IIE protein was increased to 172% by fasting. These changes reflected on catalytic activities, such as aniline hydroxylase and N-nitrosodimethylamine demethylase activities, which were decreased to about 45% and 28%, respectively, of the control levels by fasting, while in fasting rats, the catalytic activities of these enzymes were 2-3-fold higher than in controls.

Aniline Hydroxylase↗

PubMed1992

Immunocytochemical observation of paraquat-induced alveolitis with special reference to class II MHC antigens.

The expression of class II major histocompatibility complex (MHC) antigens on alveolar epithelial cells and macrophages was investigated immunocytochemically in paraquat-induced alveolitis in the rat lung. Until 2 days after paraquat injection, class II MHC antigens were expressed on the type II alveolar epithelium without any inflammatory cellular infiltration. From the 4th to the 7th day after paraquat injection, class II MHC antigen-positive macrophages increased in the alveolar spaces, whereas the expression on the type II alveolar epithelium became obscure. Over 10 days after the injection, interstitial fibrosis progressed and the intra-alveolar inflammatory infiltrates decreased. Epithelial cells lining the thickened fibrous septa no longer expressed class II MHC antigens. These results suggest that chemical stimuli can induce class II MHC antigen expression on the type II alveolar epithelium in the early stage of cellular injury, followed by inflammatory infiltration and interstitial fibrosis.

Alveolitis, Extrinsic Allergic↗

PubMed1992

Human fetal liver cytochrome P-450: capacity to form genotoxic metabolites.

Unlike most experimental animals, human fetal liver possesses forms of cytochrome P-450. Thus, the purpose of this study was to clarify the toxicological significance of these forms of cytochrome P-450 to understand possible roles of these cytochromes in producing genotoxic metabolites from promutagens. In fact, human fetal livers showed considerable capacity to activate aflatoxin B1 and IQ (2-amino-3-methylimidazo [4,5-f] quinoline). Three of four forms of cytochrome P-450, P-450HFLa-d, which we could purify from human fetal livers were capable of activating promutagens to mutagens. One of these three forms, namely P-450HFLa, catalyzed the metabolic activation of aflatoxin B1 and IQ. An expression plasmid containing HFL33 cDNA encoding P-450HFLa was constructed and the protein expressed in insect (Sf9) cells and in human cancer cells, MCF-7. Aflatoxin B1 was efficiently activated to a mutagen upon addition of the lysate of Sf9 cells to the incubation mixture for the assay. Transformants of MCF-7 cells expressing P-450IIIA7 (HFLa) showed higher sensitivity to aflatoxin B1 than the parental MCF-7 cells as detected by cytotoxicity.

Animals↗

PubMed1992

[Hemodynamic difference accounted for the orientation of a Björk-Shiley mitral prosthesis: a color Doppler echocardiographic study].

To determine whether the orientation of the major orifice of a mitral tilting disc prosthesis affects hemodynamics, intracavitary blood flow patterns were studied in 45 patients with well-functioning Björk-Shiley mitral prosthesis using color Doppler flow imaging. The major orifice was oriented towards the septum in 23 patients (12 men, 11 women, age 58 +/- 11 years; group S), and towards the posterior wall in 22 patients (8 men, 14 women, age 55 +/- 9 years; group P). 1) The left ventricular end-diastolic dimensions (S: 4.8 +/- 0.9 cm, P: 5.2 +/- 1.0 cm), end-systolic dimensions (S: 3.6 +/- 0.9 cm, P: 3.8 +/- 1.2 cm), and left atrial dimensions (S: 5.0 +/- 1.0 cm, P: 4.7 +/- 0.9 cm) did not differ significantly between the 2 groups. 2) The peak mitral flow velocities (S: 1.43 +/- 0.38 m/sec, P: 1.43 +/- 0.27 m/sec), pressure gradients (S: 8.5 +/- 4.0 mmHg, P: 8.4 +/- 3.1 mmHg), and pressure half-times (S: 94.0 +/- 19.0 msec, P: 86.5 +/- 21.7 msec) did not differ significantly between the 2 groups. 3) Although mitral regurgitation was detected in 8 patients (35%) in the S group and in 2 patients (9%) in the P group, hemodynamically significant regurgitation was detected in only 4 patients in the S group (3 mild, one moderate). 4) The patients in the S group had reversed intracavitary blood flow; mitral flow was first directed towards the left ventricular outflow tract during diastole, while the outflow pattern was displaced into the left ventricular inflow tract.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗

PubMed1992

[Treatment of cardial varicose bleeding by trans-ileocolic vein obliteration combined with endoscopic injection sclerotherapy].

In the past 4 years, 11 patients with cardial varix bleeding were experienced. The cardial varices were of 2 types, nodular and serpentine. The nodular varices were caused by gastro-renal shunt and the site of bleeding often existed on the posterior wall. The serpentine cardial varices were an extension of esophageal varices, and the site of bleeding was often on the lesser curvature. The nodular varices had an abundant blood flow. When EIS was performed to these varices independently, the time of contact with the sclerosing agent was so short that no therapeutic effect was obtained. For the purpose of decreasing the blood flow in these varices, TIO was performed first and then EIS was used in the treatment of four cases of nodular varix bleeding. Hemostasis was obtained in two of the four cases with TIO alone, and after the addition of EIS a good hemostatic and varix-reducing effect was noted in all four cases.

Aged↗

PubMed1991

Absence of evidence for a significant background incidence of diffuse malignant mesothelioma apart from asbestos exposure.

The incidence of diffuse malignant mesothelioma is rising. Physicians can diagnose a disease only when they know that it exists, so one explanation for the rise in incidence is more widespread appreciation of the clinical and pathological features of the disease. Modern pathology has ascribed specific requirements for the diagnosis of diffuse malignant mesothelioma. A priori one cannot assume that these requirements have increased the likelihood of the diagnosis because the requirements also can serve to exclude the diagnosis depending on the findings. Most cases of diffuse malignant mesothelioma are suspected by macroscopic and routine microscopic techniques that have been available since the last part of the nineteenth century. Although single reported instances of some pulmonary diseases have survived from the nineteenth century, pathologists did not identify enough cases to convincingly establish the existence of diffuse malignant mesothelioma of the pleura as an entity until the 1930s or 1940s. One must conclude that the background level of diffuse malignant mesothelioma in Europe and in the United States prior to 1930 was extremely low. No case was detected at the Massachusetts General Hospital until 1946.

Asbestos↗

PubMed1991

Occurrence of autoimmune antibodies to liver microsomal proteins in association with fulminant hepatitis in the LEC strain of rats.

The Long Evans Cinnamon (LEC) rat, which has been established as a strain showing hereditary hepatitis and hepatic carcinoma, was found to possess autoimmune antibodies to liver microsomal proteins, particularly to a protein with the molecular weight of 56kD. The antibodies also recognized a protein(s) in liver microsomes from Long Evans Agouti and Sprague-Dawley rats. About 42 and 15 percent of respective female and male LEC rats died within a week after acute hepatitis; sera from all of the animals contained the antibodies. About 43 and 0 percent of the surviving female and male LEC rats possessed the antibodies, respectively. These results suggest that the autoantibodies occur in association with acute lethal hepatitis in the LEC rats.

Animals↗

PubMed1991

A novel missense mutation in exon 8 of the ornithine transcarbamylase gene in two unrelated male patients with mild ornithine transcarbamylase deficiency.

We studied two unrelated male probands with mild ornithine transcarbamylase (OTC) (E.C.2.1.3.3) deficiency presenting a similar clinical course. Previous analyses of their liver OTCs also revealed similar properties. To identify the underlying molecular defects, we first cloned the entire coding region of the OTC gene from one proband and found a single base-substitution (C to T) leading to the substitution of tryptophan for arginine at amino acid position 277. Using a genomic amplification technique followed by allele specific oligonucleotide hybridization, we identified the same point mutation in the OTC gene of the other proband. We observed the presence of the mutation among family members in at least three generations, and in one asymptomatic hemizygous sibling in each family.

Alleles↗

PubMed1991

Application of single-locus hypervariable region DNA probes to deficiency cases in paternity testing.

Seven DNA probes which recognize single-locus hypervariable region (HVR) were applied to a paternity test in which the putative father and his wife were deceased. Three legitimate children, an illegitimate child and her mother were available for analysis. The cumulative paternity index of the illegitimate child derived from 15 conventional blood group markers was 18.71 and from 7 DNA probes 92,572.08, that is, 4,948 times higher than the former. Thus the DNA analyses gave nearly conclusive evidence that the putative father was the biological father of the child. The application of highly discriminating polymorphisms of DNA which recognize single HVR loci is considered to be extremely informative in cases of disputed parentage.

Child↗

PubMed1991

A 3' splice site consensus sequence mutation in the intron 3 of the alpha-galactosidase A gene in a patient with Fabry disease.

Fabry disease is an X-linked disorder accompanied with accumulation of glycosphingolipids resulting from the deficient activity of the lysosomal hydrolase, alpha-galactosidase A (alpha-GalA). In the present study, mRNA for alpha-GalA in fibroblasts from an 11-year-old Japanese patient with Fabry disease was examined using the reverse transcriptase-polymerase chain reaction (PCR). The shorter message of alpha-GalA was demonstrated in this patient when compared with the normal control. The complete deletion of exon 4 in the mRNA for alpha-GalA in the patient was disclosed by analysis of cDNA with restriction enzyme digestion and asymmetrical PCR sequencing. The direct sequencing of the genomic DNA demonstrated a single base substitution (G----A) at the 3' end of the consensus sequence of intron 3. This mutation destroyed a splice site in the alpha-GalA, which produced a mutant allele. It was also shown that the mother of the patient had this mutant as well as normal alleles as a heterozygote.

Child↗

PubMed1991

Aberrant pancreas is not susceptible to alcoholic pancreatitis.

Three cases of chronic alcoholic pancreatitis associated with aberrant pancreas are reported. All three patients underwent laparotomy, and an aberrant pancreas was found in the jejunum of each of the three patients. Microscopic examination of the aberrant pancreas did not show any changes suggestive of chronic pancreatitis, despite severe chronic pancreatitis in the main pancreas.

Adult↗

PubMed1991

Atypical mesothelial hyperplasia associated with bronchogenic carcinoma.

Atypical mesothelial hyperplasia encountered in pleural fluid or in a pleural biopsy specimen raises the suspicion that one may be dealing with a diffuse malignant mesothelioma of the pleura. We studied eight cases with cytologic or histologic changes of mesothelial atypia thought to be suspicious for diffuse malignant mesothelioma. In each case, the hyperplasia was associated with a bronchogenic carcinoma in the lung subjacent to the mesothelial hyperplasia. Bronchogenic carcinoma should be added to the list of causes of atypical mesothelial hyperplasia. This combination of reactive and malignant processes should be appreciated, since pleural carcinomatosis and diffuse malignant mesothelioma must be separated for clinical and epidemiologic reasons.

Adenocarcinoma↗

PubMed1991

A new approach of weighted integration technique based on accumulated images using dynamic PET and H2(15)O.

We developed a new technique of weighted integration for the measurement of local cerebral blood flow (LCBF) and the blood-tissue partition coefficient (p) using dynamic positron emission tomography (PET) and H2(15)O. The weighted integration in the new technique is carried out on the equation of the first time integration of the Kety-Schmidt differential equation. Practically, serially accumulated images with sequentially prolonged accumulation times are weighted by two arbitrary functions. The weighting functions do not have to be differentiated because of the exclusion of the differential term in the starting equation. Consequently, the method does not require data at the end of the scan. The technique was applied to H2(15)O dynamic PET performed on four normal subjects, and was verified to provide a better signal-to-noise ratio than the previously developed integrated projection (IP) technique. Computer simulations were carried out to investigate the effects of statistical noise, tissue heterogeneity, and time delay and dispersion in arterial input function. The simulation showed that the new technique provided about a 1.4 times lower statistical error in both LCBF and p at 50 ml 100 g-1 min-1 compared to the IP technique, and it should be noted that the new technique was less sensitive to the shape of the weighting functions. The new technique provides a new strategy with respect to the statistical error for estimation of LCBF and p.

Adult↗

PubMed1991

A novel subpopulation of CD45RA+ CD4+ T cells expressing IL-2 receptor alpha-chain (CD25) and having a functionally transitional nature into memory cells.

Differential expression of various isoforms of leukocyte common antigen (CD45), which arises from alternate mRNA splicing, identifies naive and memory populations of human T cells. Some memory (CD45RO+ CD45RA-) populations of CD4+ T cells from adult individuals express IL-2 receptor (IL-2R) alpha-chain (CD25), but naive (CD45RO- CD45RA+) CD4+ T cells only do so to a small degree. We found that a small but significant fraction of CD4+ T cells in neonatal blood expressed CD25, although most generally exhibited the phenotype of naive cells. It was demonstrated that purified neonatal CD25+ CD4+ T cells expressed mRNA for the IL-2R alpha-chain. Two-color immunofluorescence analysis disclosed that a CD25+ population of neonatal CD4+ T cells had the naive (CD45RA+ CD45RO-) phenotypes. These CD25+ CD4+ T cells from newborns could express mRNA for some specified lymphokines such as IL-4, IL-5, and interferon-gamma on activation in a similar manner to CD45RO+ (memory) CD4+ T cells from adults. Notably, polymerase chain reaction analysis demonstrated that neonatal CD45RA+ CD4+ T cells expressing CD25 contained spliced mRNA transcripts possibly encoding CD45RO in addition to CD45RA-associated transcripts, seemingly indicating that this population might be in the recently antigen-primed states. Such a small population of CD45RA+ CD4+ T cells expressing CD25 appeared to be present in the blood throughout human life. The results suggest that CD4+ T cells with the naive (CD45RA+) phenotype expressing IL-2R alpha-chain (CD25) represent the novel transitional population in the maturation process of naive into memory CD4+ T cells.

Adult↗

PubMed1991

Tissue distribution of mouse mammary tumor virus (MMTV) antigens and new endogenous MMTV loci in Japanese laboratory mouse strains.

The distribution of mouse mammary tumor virus (MMTV) antigens was studied by the immunoperoxidase method in the II-TES and I-TES mouse strains as well as their progenitors, CS and DBA/2 strains. In the II-TES, I-TES and CS strains, and BALB/c mice foster-nursed with these strains, MMTV antigens were found not only in epithelial cells of the mammary glands but also in those of other tissues including the seminal vesicle, vas deferens, epididymis, prostate, parotid, submandibular, lacrimal, sebaceous, and urethral glands. In DBA/2 and BALB/cfDBA/2 mice, however, the MMTV antigens were found only in the mammary glands. Electron microscopic examination showed MMTV particles in these organs. When we examined the presence of Mtv-1 and 2 proviruses, which are known to be responsible for MMTV expression, in the genomes of the II-TES, I-TES, CS and DBA/2 strains by Southern blotting, Mtv-2 was not found in any of the mice and Mtv-1 was found in the II-TES and DBA/2 mice but not in the I-TES and CS mice. Instead, four new endogenous MMTV loci, which have never previously been reported in laboratory mouse strains, were detected in the genomes of the II-TES, I-TES and CS strains. One (designated Mtv-42) was common in the three strains and the other three (designated Mtv-43, 44 and 45) were common in the II-TEX and I-TES strains or the II-TES and CS strains. These results thus suggest that new endogenous MMTV loci may be responsible for MMTV expression in a variety of tissues of these three strains.

Animals↗

PubMed1991

Expression of CD45R0 (UCHL1) by CD4+ and CD8+ T cells as a sign of in vivo activation in infectious mononucleosis.

CD45R0 (UCHL1), a member of leucocyte common antigen family, is expressed largely on previously activated or memory T cells. We examined CD45R0 expression of T cell subpopulations in patients with Epstein-Barr virus (EBV) induced infectious mononucleosis (IMN) as a sign of in vivo activation. Consistent with the notion that activated CD8+ T cells expand in acute IMN; the majority of CD8+ T cells in patients with acute IMN expressed CD45R0 to the similar extent to HLA-DR expression. Most CD4+ T cells in these patients also demonstrated marked expression of CD45R0 as well as HLA-DR antigens, compared with age-matched controls. Expression of CD45R0 by CD4+ T cells in patients with acute IMN was more notable than their HLA-DR expression. While predominant CD8+ T cells resulted in decreased percentages of CD4+ T cells, CD4+ T cells expressing CD45R0 were shown to be significantly elevated in absolute number. The results suggest that both CD4+ and CD8+ T cells may be activated by stimulation with EBV infection. The appearance of two T cell subpopulations expressing CD45R0 in acute IMN implies their immunoregulatory roles in the control of EBV-infected cells.

Antigens, CD↗