Biomedical subjects

T Hayashi

Publications and source records attributed to T Hayashi.

At least 451 records · Page 25Linked to original sources

PubMed2000

Delayed resolution of intracranial germinoma after radiotherapy: a preliminary study of the correlation between histology and magnetic resonance imaging.

A central nervous system germinoma is curable in most cases by radiotherapy, and most of the tumor mass disappears promptly after 20-30 doses. However, some germinomas take a longer period to vanish completely from magnetic resonance imaging (MRI) or computed tomography (CT) scans. In such cases, the tumor may contain components such as teratoma. The aim of this study was to clarify the nature of the persistence of some germinomas. Five cases of histologically verified germinoma in which radiotherapy was performed to treat residual tumor were selected. The doses of focal radiotherapy and whole brain radiotherapy were 10-20 Gy and 20-34 Gy, respectively. In these cases, correlation was made between the degree of persistence of the tumor when assessed by MRI and the amount of interstitial content, as determined by histology. The histological evaluation, using hematoxylin-eosin stain, silver impregnation and Azan staining was carried out independently of clinical information. The tumor vanished soon after radiotherapy in three cases, but 3-15 months passed before the tumor completely vanished from the MRI scans in the other two cases. The histology of the cases in which the tumor disappeared rapidly was predominantly of large tumor cells and only small amounts of reticulin. However, in the persistent tumors, large amounts of reticulin and vascular components were present. Thus, it is proposed that tumors with a large parenchymal component disappear soon after radiotherapy, whereas tumors composed mainly of interstitial component persist. Long-standing enhancement seen on MRI or CT scans of patients with an intracranial germinoma is indicative of a large amount of interstitial component in the tumor.

Adolescent↗

PubMed2000

Brain surface ependymoma.

A case of brain surface ependymoma is reported here. A 41-year-old woman presented with weakness of the right upper limb. Magnetic resonance imaging revealed a left fronto-parietal cystic tumor with a calcified mural nodule. Total removal of the tumor was performed. This tumor was located within the surface portion of the fronto-parietal parenchyma and was sharply demarcated from the surrounding brain tissue, and there was no continuity with the ventricles. Histological examination of this tumor showed monotonous proliferation of tumor cells with moderate cellularity and occasional mitoses, forming true ependymal rosettes and perivascular pseudorosettes with fibrillary background. A clear cell component resembling oligodendroglioma was partly noted. The tumor cells showed positive immunoreaction for glial fibrillary acid protein and vimentin.

Adult↗

PubMed2000

An evaluation of Bosniak's radiological classification of cystic renal masses.

OBJECTIVE: To determine the clinical usefulness of Bosniak's classification of cystic renal masses, the differentiation of which remains difficult despite significant advances in diagnostic imaging. PATIENTS AND METHODS: The computed tomography (CT) findings of all histopathologically examined cystic renal masses diagnosed at our institution were analysed retrospectively; 35 patients with cystic renal masses were treated between 1986 and 1998. Tissues surgically removed were examined pathologically and the final diagnosis compared with the preoperative CT category of Bosniak's classification. RESULTS: The histopathological examined showed cystic renal cell carcinoma in 21 patients, a benign renal cyst in 12, haemangiosarcoma in one and transitional cell carcinoma in one. Most of the 35 masses (26, 74%) were found incidentally during evaluation for an unrelated disease or a routine health check. All 11 masses of Bosniak category I were benign and one category II mass was malignant. All 10 masses of category III and 12 of category IV were malignant. CONCLUSIONS: Bosniak's classification is useful for differentiating category I, III and IV cystic renal masses. There were too few samples to allow meaningful conclusions to be drawn for category II renal masses. It is critical to differentiate between complicated cysts of category II and III because of the major implications for prognosis and clinical management.

Adult↗

PubMed2000

Leisure-time physical activity at weekends and the risk of Type 2 diabetes mellitus in Japanese men: the Osaka Health Survey.

AIMS: To investigate association between leisure-time physical activity at weekends and the risk of developing Type 2 diabetes mellitus (DM). METHODS: Prospective examination of 6,013 Japanese men aged 35-60 years who were free of DM, impaired fasting glycaemia, or hypertension at study entry. Type 2 DM was defined by a fasting plasma glucose level > or = 7.0 mmol/l or a 2-h post-load plasma glucose level > or =11.1 mmol/l. Data on physical activity obtained from questionnaires consisted of overall leisure-time physical activity weekly and leisure-time physical activity at weekends. RESULTS: During the 59,966 person-years follow-up, 444 cases developed Type 2 DM. Regular physical exercise at least once a week was associated with a reduced risk of Type 2 DM. After adjustments for age, body mass index, daily alcohol consumption, smoking habits, blood pressure levels and a parental history of Type 2 DM, men who engaged in regular physical exercise at least once a week had a relative risk of Type 2 DM of 0.75 (95% CI, 0.61-0.93) compared with men engaging in exercise less often. Even vigorous activity only once a week at weekends was associated with a reduced risk of Type 2 DM. Men who engaged in vigorous activity at least once a week at weekends had a multiple-adjusted relative risk of Type 2 DM of 0.55 (95% CI, 0.35-0.88) compared with sedentary men. CONCLUSIONS: Regular physical exercise at least once a week and vigorous activity even only once a week at weekends are associated with a decreased risk of Type 2 DM.

Adult↗

PubMed2000

The effect of biofiltration on red blood cells 2.3-diphosphoglycerate and pH.

To investigate the effect of biofiltration (BF) on the ability of blood to supply oxygen to the peripheral tissues, a 2 week crossover study was conducted with bicarbonate hemodialysis (BcHD) and BF using 5 male patients with diabetic renal failure as subjects. BcHD and BF were performed for 4 h and 3.5 h per session, respectively. Blood gases, the pH of red blood cells (RBC-pH), and 2. 3-diphosphoglycerate in RBC (RBC-2.3DPG) were measured during each treatment. After a 2 week BF treatment, the plasma HCO3- at the beginning of BF was significantly higher than that of BcHD (p < 0.01), and the blood pH improved with an elevated plasma bicarbonate level (p < 0.05). The RBC-pH at the beginning of BF was higher than that of BcHD (p < 0.05) although the RBC-pH at the end of both therapies increased to similar levels. The RBC-2.3DPG during BcHD remained unchanged, but during BF significantly increased (p < 0.05). Metabolic acidosis was significantly improved by BF with its effect reaching to the RBC intracellular level. The improved metabolic acidosis might occur as a result of the increase in RBC-2.3DPG during BF. This increase in RBC-2.3DPG has the effect of reducing the affinity of oxygen for hemoglobin and allows more oxygen to be delivered to the peripheral tissues although the increase in RBC-pH by dialysis restricts the dissociation of oxygen from hemoglobin.

2,3-Diphosphoglycerate↗

PubMed2000

Increased digitalis-like immunoreactive substances in patients with hypertrophic cardiomyopathy.

AIMS: Although increased digitalis-like immunoreactive substances have been found in cases of hypertension and heart failure, no information is available about digitalis-like immunoreactive substances in patients with hypertrophic cardiomyopathy. We investigated digitalis-like immunoreactive substances in the plasma and biopsied specimens of patients with hypertrophic cardiomyopathy. METHODS AND RESULTS: In 40 patients with hypertrophic cardiomyopathy (27 with the non-obstructive type and 13 with the obstructive type), the plasma concentration of digitalis-like immunoreactive substances was studied by fluorescence polarization immunoassay. Right ventricular endomyocardial biopsy specimens were analysed immunohistochemically, using a monoclonal antibody against digoxin. An increase in digitalis-like immunoreactive substances of more than 0.2 ng. ml(-1)in plasma was found in six of 27 patients with non-obstructive hypertrophic cardiomyopathy (22.2%) and five of 13 with obstructive hypertrophic cardiomyopathy (38.4%). Under light microscopy, positive staining against the antibody was observed heterogeneously on some cardiocytes. In non-obstructive hypertrophic cardiomyopathy, digitalis-like immunoreactive substances in the plasma correlated with the left atrial dimension and inversely with the cardiac index. In obstructive hypertrophic cardiomyopathy, plasma and myocardial digitalis-like immunoreactive substances were positively correlated; they also correlated with left ventricular end-diastolic pressures. Under electron microscopy, digitalis-like immunoreactive substances were detected at the sarcolemma in the free wall, T-tubules, intercalated discs and Z-bands of cardiocytes. CONCLUSIONS: Increased digitalis-like immunoreactive substances in plasma and cardiocytes, which may have been caused by pressure and/or volume overload, were found in patients with hypertrophic cardiomyopathy. Digitalis-like immunoreactive substances may act on the sarcolemma of cardiocytes and be transported into the cytoplasm.

Adult↗

PubMed2000

A possible link between beta -carboline metabolism and infantile autism.

Benzodiazepine receptors and abnormal hepatic metabolism have been suggested to participate in several neuropsychiatric disorders including autism. Neuropsychoactive beta-carboline alkaloids as the potent ligands for benzodiazepine receptors are endogenously produced and exogenously supplied much more than benzodiazepines. 1-Methyl-1,2,3,4-tetrahydro-beta-carboline, a predominant alkaloid in humans and foodstuffs, is metabolically hydroxylated in liver. Although its in vivo levels show no difference between autistic and healthy children, the metabolic 6-hydroxylation is significantly decreased in autistic subjects. Therefore, it could be hypothesized that the reduced hepatic metabolism of 1-methyl-1,2,3, 4-tetrahydro-beta-carboline to 6-hydroxyl metabolite may be linked to the pathogenesis of infantile autism as suggested for autistic occurrence to involve the pathology similar to hepatic encephalopathy.

Autistic Disorder↗

PubMed2000

Inhibitory effects of lignans and flavonoids in saiboku-to, a herbal medicine for bronchial asthma, on the release of leukotrienes from human polymorphonuclear leukocytes.

To identify the anti-allergic components contained in Saiboku-To, a herbal medicine for the treatment of bronchial asthma, we studied the effects of eight phenolic compounds, which have been identified as the major human metabolites of Saiboku-To, and three triterpenoids contained in Saiboku-To on the release of leukotriene (LT) from human polymorphonuclear leukocytes (PMLs) stimulated with Ca(2+)-ionophore A23,187. All phenolic compounds exhibited dose-dependent suppression on release of both LTB4 and LTC4, while triterpenoids did not show any effects, except for glycyrrhetinic acid, which selectively inhibited LTC4-release. The five phenolic compounds, magnolol, dihydroxydihydromagnolol, baicalein, medicarpine and davidigenin, were found to exert a marked inhibition on LTB4- and LTC4-release with IC50 values of 0.7-15.3 microM. The results suggest that the phenolic compounds contribute to the anti-allergic effects of Saiboku-To through suppression of LT-release from PMLs.

Anti-Asthmatic Agents↗

PubMed2000

Pharmacological effects of urinary products obtained after treatment with saiboku-to, a herbal medicine for bronchial asthma, on type IV allergic reaction.

To define the anti-allergic components in Saiboku-To, a herbal medicine for bronchial asthma, we examined the effects of 11 compounds found in post-administrative urine of Saiboku-To on concanavalin A-induced human lymphocyte blastogenesis in vitro and picryl chloride (PC)-induced mouse ear swelling in vivo. The urinary products of Saiboku-To were flavonoids and lignans derived from the constitutional herbs and their hydrogenated metabolites. Medicarpin derived from Glycyrrhiza glabra, magnolol and 8,9-dihydroxydihydromagnolol from Magnolia officinalis, baicalein, wogonin and oroxylin A from Suctellaria baicalensis inhibited lymphocyte blastogenesis in dose-dependent fashion with IC50 values ranging from 3.0 to 7.7 micrograms/mL, which corresponded to 20-100 times that of prednisolone IC50 (0.08 microgram/mL). Davidigenin, dihydrowogonin and dihydrooroxylin A, which are hydrogenated metabolites of liquiritigenin, wogonin and oroxylin A, respectively, had no or little effects on lymphocyte blastogenesis. Oral administration of Saiboku-To, medicarpin, baicalein, magnolol and baicalin (100 mg/kg), inhibited PC-induced ear swelling significantly by 23.5, 40.1, 30.5, 23.6 and 20.9%, respectively, though the effects were weaker than that of 5 mg/kg of prednisolone (52.9%). The results suggested that flavonoids and lignans tested in the present study were implicated in anti-asthmatic effect of Saiboku-To through suppression of type IV allergic reaction.

Animals↗

PubMed2000

Molecular pathogenesis of Bernard-Soulier syndrome.

Bernard-Soulier syndrome (BSS), a hereditary qualitative platelet disorder, is now proved to be caused by a qualitative or quantitative abnormality of the platelet glycoprotein (GP) Ib/IX/V complex. We investigated the genetic background of two Japanese females with BSS and identified the molecular defects underlying this disease. The first case was a single base pair deletion within seven adenine repeats at position 4464-4470 (EMBL, no. M22403) of the GPIbalpha gene resulting in a frameshift and a premature stop codon. The second case was a single T-->C substitution at nucleotide 1856 (EMBL, no. M80478) of the GPIX gene resulting in Phe55(TTT)-->Ser(TCT) substitution. The latter case is of interest in considering the pathogenesis of BSS, because all four GPs consisting of the GPIb/IX/V complex have the same structural unit called leucine-rich repeat (LRR). Because this mutation is located within the LRR of the GPIX polypeptide, Phe55-->Ser substitution may result in an alteration of the LRR that leads to impaired surface expression of the GPIb/IX/V complex. To clarify the effect of this mutation on surface expression of the GPIb/IX complex, we performed transfection studies with a plasmid having this mutation. Mutant GPIX could not increase surface expression of the GPIb/IX complex, thus demonstrating an important role of the LRR of the GPIX polypeptide during biosynthesis.

Amino Acid Sequence↗

PubMed2000

cis-elements required for expression of human protein C inhibitor gene in HepG2 cells and its androgen-dependent expression in rat reproductive organs.

Protein C inhibitor (PCI) is a plasma serine protease inhibitor of activated protein C, which is the main protease of the anticoagulant protein C pathway. Human PCI is synthesized in the liver, kidney, and several reproductive organs (testis, seminal vesicle, and prostate). In the present study, we characterized cis-elements of the human PCI gene required for expression in the hepatoma-derived cell line, HepG2 cells, and also evaluated rat PCI mRNA expression, particularly on the effect of androgen in rat reproductive tissues. On the PCI gene expression in HepG2 cells, transient expression assays using several deletion mutants and site-directed mutants of the human PCI gene and gel mobility shift assays using several synthetic oligonucleotides showed that the Spl-binding site (residues -302 to -294) and the upstream AP2-binding site (residues -350 to -343) play roles as the promoter and the enhancer, respectively. Both the A-activator-binding site (residues -422 to -414) and the interferon-gamma response element (residues -164 to -157) serve as the silencer. In the study on PCI mRNA expression in the reproductive organs, we first cloned rat PCI cDNA and then evaluated the effect of androgen on the PCI mRNA expression. The isolated rat PCI cDNA contained a 1,218-bp coding region of a 406-amino acid precursor protein. The deduced amino acid sequence of rat PCI showed an 85.7% and 62.2% homology with that of mouse and human PCIs, respectively. Northern blot analysis showed that rat PCI mRNA was strongly expressed in the seminal vesicles, moderately in the testes, but not in the liver. PCI mRNA expression in seminal vesicles and testes increased during the process of development. The PCI mRNA expression in seminal vesicles was significantly decreased after castration or after 17beta-estradiol treatment. Treatment with testosterone in the castrated rats significantly enhanced its mRNA expression. These findings suggest that the PCI gene expression in rat seminal vesicles is under androgen control.

Amino Acid Sequence↗

PubMed2000

A novel hydroxyl radical scavenger, nicaraven, protects the liver from warm ischemia and reperfusion injury.

BACKGROUND: Reactive oxygen species have been considered to be involved in liver injury at the procurement, preservation, and transplantation from donors without beating hearts. A novel hydroxyl radical scavenger, nicaraven with hydrophilic and lipophilic properties, infiltrates both intracellular and extracellular spaces where it effectively scavenges reactive oxygen species. Protection by nicaraven against ischemia and reperfusion damage of the brain, heart, and kidneys has been shown. The effect of this agent on the liver remains unclear. METHODS: Two-hour total hepatic vascular exclusion was used. Eighteen beagle dogs were randomly assigned to 2 groups: 12 animals were not treated (group I) and 6 were treated with nicaraven (group II). Nicaraven was administered intravenously (2mg/kg/min) for 60 minutes before ischemia and for 3 hours, starting 30 minutes before reperfusion. RESULTS: Two-week survival rates were 25% in group I and 100% in group II (P <.01). Nicaraven inhibited lipid peroxidation in the liver, improved hepatic and systemic hemodynamics and energy metabolism, and suppressed liver enzyme release, endothelin-1 elevation in hepatic venous blood, histologic damage, and neutrophil infiltration into the liver. CONCLUSIONS: Nicaraven exerted hepatic protection against warm ischemia and reperfusion injury. This may indicate nicaraven as a potential candidate to attenuate liver injury from warm ischemia and preservation in transplantation from donors without beating hearts.

Adenine Nucleotides↗

PubMed2000

Adenovirus-mediated glial cell line-derived neurotrophic factor gene delivery reduces motor neuron injury after transient spinal cord ischemia in rabbits.

OBJECTIVE: Glial cell line-derived neurotrophic factor (GDNF) has protective effects on various injuries involving the central and peripheral nervous systems in vitro and vivo. However, the possible protective effect of GDNF on spinal cord ischemia and the exact mechanism involved in the ameliorative effect of GDNF on ischemic spinal cord injuries are not fully understood. Therefore, we investigated the possible protective effect of the adenovirus-mediated GDNF gene delivery on transient spinal cord ischemia in rabbits. METHODS: The adenoviral vector (lacZ gene as a control or GDNF gene contained) was injected directly into the lumbar spinal cord via a needle inserted into the dorsal spine 2 days before the animal was subjected to 15 minutes of spinal cord ischemia induced by infrarenal aortic occlusion. In situ terminal deoxynucleotidyl transferase (TdT)-mediated dUTP-biotin nick-end labeling (TUNEL staining) was performed, and temporal profiles of the GDNF and caspase-3 (caspase-3 is the marker of apoptotic change) immunoreactivity were investigated. RESULTS: In the control rabbit, the majority of motor neurons showed selective cell death at 7 days of reperfusion. Immunocytochemistry showed that in situ TUNEL staining was selectively detected at 2 days of reperfusion in motor neuron nuclei. GDNF and caspase-3 were selectively induced in the motor neuron cells at 8 hours of reperfusion. In the GDNF-treated group, a large population of motor neuron cells was still surviving at 7 days after having been subjected to 15 minutes of ischemia. Unlike the control group, the GDNF-treated group expressed GDNF persistently. Induction of TUNEL staining and immunoreactivity for caspase-3 were greatly reduced by the GDNF treatment. CONCLUSION: These results suggest that the reduction in motor neuron death by GDNF was greatly associated with a reduction in DNA fragmentation and apoptotic signals of the caspase-3 cascade; they further suggest a great potential for gene therapy for paraplegic patients in the future.

Adenoviridae↗

PubMed2000

Protective effect of ginkgo extract on rat brain with transient middle cerebral artery occlusion.

It has been empirically known that Ginkgo extract is useful for reducing many symptoms associated with cerebral blood flow (CBF) insufficiency, but its mechanisms have been uncertain. In the present study, therefore, we gave Ginkgo extract to rats with per os digestion, and investigated its effect on CBF and ischemic brain damage with middle cerebral artery occlusion (MCAO). The treatment with Ginkgo extract (10 mg 100 g-1 rat) increased CBF in the normal condition, but the degree of increase in CBF was lesser during and after MCAO. TTC staining showed that infarct volume was reduced with Ginkgo treatment. TUNEL and HSP72 immunostaining confirmed the protective effect of Ginkgo treatment reducing numbers of TUNEL and HSP72 positive cells. Immunohistochemical analysis showed that caspase-3 expression was less abundant in Ginkgo treated rats. The present results suggest that Ginkgo extract contains a substance which increases normal CBF and reduces ischemic brain damage.

Animals↗

PubMed2000

Characterization of activated carbon fiber filters for pressure drop, submicrometer particulate collection, and mercury capture.

The use of activated carbon fiber (ACF) filters for the capture of particulate matter and elemental Hg is demonstrated. The pressure drop and particle collection efficiency characteristics of the ACF filters were established at two different face velocities and for two different aerosols: spherical NaCl and combustion-generated silica particles. The clean ACF filter specific resistance was 153 kg m-2 sec-1. The experimental specific resistance for cake filtration was 1.6 x 10(6) sec-1 and 2.4 x 10(5) sec-1 for 0.5- and 1.5-micron mass median diameter particles, respectively. The resistance factor R was approximately 2, similar to that for the high-efficiency particulate air filters. There was a discrepancy in the measured particle collection efficiencies and those predicted by theory. The use of the ACF filter for elemental Hg capture was illustrated, and the breakthrough characteristic was established. The capacity of the ACF filter for Hg capture was similar to other powdered activated carbons.

Air Pollution↗

PubMed2000

Defective function of the proteasome in autoimmunity: involvement of impaired NF-kappaB activation.

Type 1 diabetes (also known as insulin-dependent diabetes mellitus or juvenile-onset diabetes) is usually caused by T cell-mediated autoimmunity, with a prediabetic state characterized by the production of autoantibodies specific for proteins expressed by pancreatic beta cells. The nonobese patient with diabetes (NOD) mouse is a spontaneous model of type 1 diabetes with a strong genetic component that maps to the major histocompatibility complex (MHC) region of the genome. A specific proteasome defect has been identified in NOD mouse in select lymphocytic and monocytic lineages that results from down-regulation of expression of the proteasome subunit LMP2, which is encoded by a gene in the MHC genomic region. This defect prevents the proteolytic processing required for the production and activation of the transcription factor nuclear factor-kappaB (NF-kappaB), which plays important roles in immune and inflammatory responses, as well as increases the susceptibility of the affected cells to apoptosis induced by tumor necrosis factor-alpha (TNF-alpha). The novel role of the proteasome in dysfunction in autoimmunity is presented and documented to be both tissue and developmental stage specific. We propose a role of the proteasome as a step in disease pathogenesis and tissue targeting.

Animals↗

PubMed2000

Anaplastic changes associated with p53 gene mutation in differentiated thyroid carcinoma after insufficient radioactive iodine (131I) therapy.

Thirty-two patients with differentiated thyroid carcinomas with distant metastasis were examined using a radioactive iodine (131I) tracer dose prior to 131I therapy and followed up for 10 years or until death (whichever occurred first). Nineteen patients who received 131I therapy had an accumulation of 131I in the metastases (group I) and 15 of those patients were alive more than 10 years after the first 131I treatment. In contrast, all 13 patients in whom the metastases did not show accumulation of 131I died within 10 years. Of the latter group, eight patients had received 131I therapy (group II), four of whom died with anaplastic changes within 5 years of treatment. p53 gene mutation was identified by immunohistochemistry in primary thyroid carcinoma tissue from patients with anaplastic changes that were evident during total thyroidectomy. Five patients did not receive 131I therapy (group III), of whom one, who also had a p53 gene mutation in the original tumor, died with anaplastic change 10 years after thyroidectomy. Seven patients in group I had p53 gene mutations in their thyroid carcinoma tissues, but none showed anaplastic changes. Our results suggest that 131I therapy may be useful for patients with distant metastases, with or without p53 gene mutations, which show accumulation of 131I from tracer and therapeutic doses. In contrast, 131I therapy is apparently not effective in patients who do not show sufficient accumulation of 131I, but rather, may cause early anaplastic changes with a p53 gene mutation.

Adult↗

PubMed2000

Empirical Bayes procedure for estimating genetic distance between populations and effective population size.

We developed an empirical Bayes procedure to estimate genetic distances between populations using allele frequencies. This procedure makes it possible to describe the skewness of the genetic distance while taking full account of the uncertainty of the sample allele frequencies. Dirichlet priors of the allele frequencies are specified, and the posterior distributions of the various composite parameters are obtained by Monte Carlo simulation. To avoid overdependence on subjective priors, we adopt a hierarchical model and estimate hyperparameters by maximizing the joint marginal-likelihood function. Taking advantage of the empirical Bayesian procedure, we extend the method to estimate the effective population size using temporal changes in allele frequencies. The method is applied to data sets on red sea bream, herring, northern pike, and ayu broodstock. It is shown that overdispersion overestimates the genetic distance and underestimates the effective population size, if it is not taken into account during the analysis. The joint marginal-likelihood function also estimates the rate of gene flow into island populations.

Algorithms↗