Search PubMed⌕ Search

Biomedical subjects

T Nagano

Publications and source records attributed to T Nagano.

At least 217 records · Page 12Linked to original sources

[Congestive (cardiac) cirrhosis].

As the incidence of cardiac cirrhosis at autopsy today is much lower than that from decades ago, true cardiac cirrhosis is a rare finding. With the decline in incidence of valvular disease, cardiomyopathy, in the etiology of congested liver, has increased. The pathophysiology of congestive heart failure consists of two components: forward failure with decreased hepatic blood flow and backward failure with congestive liver. Both lead to hepatocellular hypoxia. Increased serum transaminases and serum bilirubin correlate with reduction in cardiac output and elevation of venous pressure. Even when cardiac cirrhosis develops, it is difficult to diagnose clinically.

Heart Failure↗

Toxicological analysis for drugs and poisons using the formalin-fixed organ tissues. 1. Methamphetamine.

Methamphetamine (MA) was analyzed using formalin-fixed organ tissues from experimental animals and an autopsied cadaver. The brain, lung, liver, kidney and skeletal muscles of rabbits that had been administered MA were collected, and then fixed with a non-buffered 10% formalin solution at room temperature (10-20 degrees C) for five different fixation periods (1, 3, 7, 14 and 28 days). After the Extrelut column extraction, MA was derivatized using anhydrous trifluoroacetic acid (TFA) and analyzed by GC-MS using a DB-17 column. MA-TFA in the eluates from the organ tissues after the formalin-fixation could be identified by GC-MS. Even one day after the formalin-fixation, concentrations of MA in the fixed organ tissues already significantly decreased to 1.3-3.1% when compared with those of MA in the non-fixed tissues, and to 0.04-0.4% in all of the fixed organ tissues at 28 days after the fixation. Moreover, MA in the organ eluates from the autopsied male cadaver after one-month formalin-fixation was qualitatively detected. These results obviously show the usefulness of MA detection using formalin-fixed organs in the practice of forensic medicine and police science.

Animals↗

Real time measurement of nitric oxide produced ex vivo by luminol-H2O2 chemiluminescence method.

Endothelium-derived relaxing factor, identified as nitric oxide (NO), is derived from a guanidino nitrogen of L-arginine via its metabolism by nitric oxide synthase. A newly developed aqua-chemiluminescence system was used to measure the amount of NO release from the isolated, perfused rat kidney concomitantly with the pressure changes (Kikuchi, K., Nagano, T., Hayakawa, H., Hirata, Y., and Hirobe, M. (1993) Anal. Chem. 65, 1794-1799). In normotensive rats, basal NO release was estimated to be 86 +/- 6 fmol min-1 (g of kidney weight)-1, and endothelium-dependent vasodilators increased NO release with a concomitant pressure reduction. Pretreatment of the kidney with detergents to damage the vascular endothelium diminished the responses of NO and perfusion pressure to acetylcholine, while infusion of authentic NO solution caused an increase in the chemiluminescence and a concomitant decrease in the pressure. The half-life of NO in O2-saturated Krebs-Henseleit buffer was determined as 6.41 s, and the decay constant (Kd) was 0.108 s-1. The measuring system involves a lag time of 15 s after passage of the solution through the kidney, so that the measured value is 13.0% of the true luminal NO concentration in the kidney, up to 400 pM. These observations enabled us to quantitate the degree to which NO released from the rat kidney changes perfusion pressure. Acetylcholine-induced vasodilation and NO release were markedly attenuated in deoxycorticosterone acetate-salt hypertensive rats, in which the endothelium is known to be markedly damaged. Thus, this assay system may make it possible to evaluate the extent of injury to the endothelium in conditions involving vascular damage.

Acetylcholine↗

Detection of nitric oxide production from a perfused organ by a luminol-H2O2 system.

Nitric oxide, thought to be the endothelium-derived relaxing factor (EDRF), is involved in intra- and intercellular signalling in various tissues. A system for the continuous detection of NO in the picomolar range from a perfused organ is described. The detection is based upon the chemiluminescence reaction between NO and the luminol (5-amino-2,3-dihydro-1,4-phthalazinedione)-H2O2 system. The chemiluminescence is due to the formation of peroxynitrite from NO and H2O2. The luminol-H2O2 system is specifically reactive to NO, so that other nitrogen-containing compounds, (organic nitrite, organic nitrate, and thio-nitroso compounds) or endothelium-derived compounds do not interfere. The limit of determination was approximately 100 fM. This system has been used to measure continuous NO release from isolated perfused rat kidney and the simultaneous changes of perfusion pressure. In Wistar rats basal NO release was 85 +/- 11 fmol/min-1 (g of kidney weight)-1 (39 pM in the perfusate), and acetylcholine increased NO release dose dependently with a concomitant pressure reduction. The changes in NO release were always associated with mirror image changes in the perfusion pressure. Simple pressure reduction did not interfere with the chemiluminescence. Precise titration data as well as results of some preliminary experiments using this method are presented.

Animals↗

Molecular cloning of the smaller subunit(P52) of rat liver mitochondrial processing protease.

A cDNA encoding the smaller subunit (P52) of mitochondrial processing protease was isolated from a rat liver cDNA library, using cDNA fragment for yeast MAS1 as the probe. The deduced amino acid sequence is highly homologous to those of PEP from Neurospora crassa and MAS1 from Saccharomyces cerevisiae. After in vitro transcription and translation, the precursor peptide was imported into isolated rat liver mitochondria and processed to its mature form.

Amino Acid Sequence↗

Eosinophil cationic protein in the nasal secretions of patients with mite allergic rhinitis.

In 25 patients with mite nasal allergy and 13 healthy control subjects, levels of eosinophil cationic protein (ECP) and histamine in nasal secretions were examined before and after challenge with mite extract. The ECP level was found to be significantly higher in the washings taken 30 minutes after challenge compared with the washings taken before challenge (P < .05). ECP levels measured both before and after mite extract challenge were found to be significantly higher in the patients than in the controls (P < .01). These facts suggest that the ECP affects the nasal mucosa by causing injury to ciliated cells and by acceleration of the processes of modification and inhibition of the allergic reaction.

Adolescent↗

A neural network model for visual motion detection that can explain psychophysical and neurophysiological phenomena.

This paper proposes a new neural network model for visual motion detection. The model can well explain both psychophysical findings (the changes of displacement thresholds with stimulus velocity and the perception of apparent motion) and neurophysiological findings (the selectivity for the direction and the velocity of a moving stimulus). To confirm the behavior of the model, numerical examinations were conducted. The results were consistent with both psychophysical and neurophysiological findings.

Animals↗

Suspected maternal infanticide in a case of hydranencephaly.

A medico-legal autopsy case of hydranencephaly in a male infant which was first suspected of maternal infanticide is reported. The infant was 48 cm in height, weighed 2.86 kg and the circumference of the head, the chest and the abdomen was 32.2 cm, 31.0 cm and 30.4 cm, respectively, with no deformities of the head or body. Autopsy examination, however, revealed a severe defect in the central nervous system. The cranial cavity was filled with a cloudy dark red fluid (ca. 310 ml) instead of the cerebral hemispheres. The residual central nervous tissues were mostly subtentorial structures from the midbrain to the spinal cord namely, corpus mamillare, corpora quadrigemina, corpus pineale, crus cerebri, pons, cerebellum, medulla oblongata and spinal cord. The basal ganglia, thalamus, hypothalamus and chiasma opticum could not be found, although atrophic hypophysis, eyeballs and optic nerves were present. The usual distribution of cerebral blood vessels, especially the branches of the anterior and middle cerebral arteries and Willis' ring, was absent despite the presence of the internal and external carotid arteries. Other organs were, in general, congestive. The marked cortical atrophy of the adrenal glands (left 0.5 g, right 0.6 g), especially the zona fasciculata, was characteristic. The hydrostatic lung test gave partially positive results, but this was considered to be due to artificial respiration by an ambulance man because amniotic fluid components were microscopically noted and fully expanded alveoli were not found. In conclusion, the cause of the infant's death was diagnosed as stillbirth due to aspiration of amniotic fluid caused by the severe defect of vegetative hypothalamic function through hydranencephaly.

Brain↗

Contacts between regenerating axons and the Schwann cells of sciatic nerve segments grafted to the optic nerve of adult rats.

The relation between Schwann cells, basal laminae and axons during retinal ganglion cell regeneration was studied by using cellular, acellular and partially acellular sciatic nerve autografts into the optic nerve. Acellular grafts were achieved by temporary compression which eliminates living Schwann cells and axons. The compressed sciatic nerve together with the intact portion was used as a partially acellular graft. The compressed portion was anastomosed to the optic nerve and the intact portion was situated distally. After 3-21 days post-operation, the grafts were studied by thin sectioning and freeze-fracture. Axons were seen to regenerate into cellular grafts in contact with Schwann cells after one week, but not into acellular grafts for the entire period. In the partially acellular grafts, regenerating axons were first observed after two weeks and were always in contact with Schwann cells migrating from the intact portion. Moreover, membrane specializations, fuzzy materials in the space between apposed membranes, and putative tight junctions, were found between regenerated axons including growth cone and Schwann cells, and between adjoining Schwann cells. An extensive meshwork of putative tight junctions was displayed between reforming perineurial cells surrounding the groups of Schwann cells and associated axons. Gap junctions were seen between adjoining Schwann cells, and between reforming perineurial cells. These results suggest that the axonal contact with Schwann cell surfaces plays an important role in retinal ganglion cell regeneration.

Animals↗

Characterization of Yersinia pseudotuberculosis serogroups O9, O10 and O11; subdivision of O1 serogroup into O1a, O1b, and O1c subgroups.

In this study, three new antigens (O9, O10 and O11) of Yersinia pseudotuberculosis are described. The O1 antigen is further subdivided into O1a, O1b and O1c. The methods used to prepare specific antisera for O-antigen identification are also described. Furthermore, the H antigens of these new serogroups are determined and their biochemical characteristics analysed. The antigenic formulae of the known serogroups within the basic antigenic scheme introduced by the authors' laboratories are presented.

Antigenic Variation↗

Right atrial contractile performance in patients with myocardial infarction.

To evaluate right atrial (RA) contractile performance in patients with myocardial infarction, we validated a cineangiographic method of RA volume measurement, and investigated RA volume change in 'normal' individuals and patients with a previous myocardial infarction. Sixteen silicone rubber RA casts made from human cadavers were filmed in the postero-anterior and left lateral projections. The cast volumes calculated following Simpson's rule were in good agreement with those measured by water replacement (r = 0.992, P < 0.01). At cardiac catheterization, biplane RA cineangiography was performed in 19 'normal' individuals (N group), in 14 patients with a previous antero-septal infarction (AMI group) and in seven patients with a previous inferior infarction (IMI group). The RA volume-time curve was constructed at 20-40 ms intervals for one cardiac cycle. RA volume at the beginning of the atrial contraction (RAVd), which was defined as the 'preload' of the RA, tended to be larger in both the AMI and IMI groups compared with 'normal' individuals. The RA ejection volume was significantly larger in both the AMI (18.4 +/- 2.1 ml.m-2, P < 0.01) and IMI groups (19.4 +/- 2.8, P < 0.01) than in the N group (14.5 +/- 1.9), even for a comparable level of RAVd (range from 26 to 36 ml.m-2) (18.6 +/- 2.1, P < 0.01, 18.2 +/- 2.0, P < 0.01, 14.7 +/- 1.9, respectively). These results suggest that RA contraction increases in patients with myocardial infarction by increasing both the 'preload' and 'contractility' of the RA.

Adult↗

Norepinephrine-induced changes in rat heart function, metabolism, and weight are antagonized by carvedilol.

One aim of our study was to characterize in intact rats the pharmacologic effects of carvedilol. After 3 days of continuous intravenous (i.v.) infusion of carvedilol (0.5 mg/kg/h), the positive chronotropic and inotropic effects of i.v. bolus injections of isoproterenol (0.1, 0.3, and 1 microgram/kg) and phenylephrine (3, 10, and 30 micrograms/kg), respectively, were measured and compared with those obtained in rats that received a continuous i.v. infusion of 0.9% NaCl, prazosin (0.1 mg/kg/h), and propranolol (0.5 mg/kg/h). The chronotropic response to isoproterenol was less blunted in carvedilol-treated animals than in propranolol-treated animals. The pressure response to phenylephrine was attenuated only moderately. Thus, carvedilol had beta-receptor blocking actions on intact rat heart that were similar to but not as pronounced as those of propranolol. Because it reduced diastolic aortic pressure (DAP) and left ventricular systolic pressure (LVSP), it also had a moderate vasodilating effect. Carvedilol (continuous i.v. infusion of 0.25 and 0.5 mg/kg/h) antagonized the effects of norepinephrine (NE, i.v. infusion of 0.2 mg/kg/h for 3 days) on heart function and heart weight in a dose-dependent manner. It also attenuated markedly the norepinephrine (NE)-induced increase in the activity of cardiac glucose-6-phosphate dehydrogenase (G-6-PD), the first and rate-limiting enzyme of the oxidative pentose phosphate pathway (PPP), although a 37% stimulation persisted.

Adrenergic beta-Antagonists↗

Mechanisms for altered endothelium-dependent vasorelaxation in isolated kidneys from experimental hypertensive rats.

To study mechanisms for attenuated endothelium-dependent vasorelaxation in hypertension, we examined the effects of acetylcholine (ACh) on renal vascular resistance (RVR) and release rates of endothelium-derived relaxing factor (EDRF) in kidneys isolated from spontaneously hypertensive rats (SHR), deoxycorticosterone acetate (DOCA) salt-hypertensive (DOCA salt) rats, and Dahl salt-sensitive (Dahl S) rats. Decreases in RVR by ACh were smaller in hypertensive rats than in their normotensive controls. The release rate of nitric oxide into the perfusate, which was estimated using nitrite-nitrate as an index, did not differ between SHR and Wistar-Kyoto rats (WKY). However, the release rate of EDRF was markedly decreased in both DOCA salt rats and Dahl S rats compared with their normotensive controls (10(-7) M ACh: DOCA salt 45 +/- 6 vs. control 410 +/- 60 pmol.min-1.g-1 kidney wt, P < 0.001). In SHR, high-K+ perfusion or pretreatment with glibenclamide, inhibitors of endothelium-derived hyperpolarizing factor (EDHF), significantly reduced ACh-induced vasorelaxation only in WKY, resulting in no differences in the RVR reduction between SHR and WKY. Thus attenuated ACh-induced vasorelaxation in the SHR kidney may be attributed to a decrease in EDHF, but to a decrease in EDRF in DOCA salt rats and Dahl S rats.

Acetylcholine↗

Clonal analysis of human T-cell responses to fractionated house dust mite antigens (Dermatophagoides pteronyssinus).

In the present study, we investigated the cellular basis of house dust mite-driven immune responsiveness in an atopic individual with perennial rhinitis. We established 40 human T-cell clones (CD3+, 4+, 8-) reactive to Dermatophagoides pteronyssinus (Dp) antigen under the restriction of HLA-DR. By using the crude Dp antigen and its 14 molecular weight (MW) fractions, we analyzed the distribution of T-cell-recognizing sites in the whole Dp extract. We tested T-cell-mediated immunity through two parameters; the identification of Dp fractions inducing T-cell proliferation, and the ability of T-cell clones to secrete IL-2, IL-4, and IFN-gamma. According to a prominent peak among fraction-driven T-cell proliferation, we observed that T-cell clones that recognized 45,000- to 95,000-MW fractions were common, while clones reactive to 15,000- to 25,000-MW fractions were less frequent. Several clones were also reactive to antigens of Dermatophagoides farinae or other insects. Based on the responses of cloned T cells, we observed at least 9 distinct T epitopes in crude Dp antigen. These T-cell clones had a heterogenous secretory pattern of cytokines. T-cell clones showed no association between their ability to produce regulatory cytokine and their recognition of particular Dp fractions.

Adult↗

Ulcerative colitis in female siblings with an identical human leukocyte antigen haplotype (A24, Bw52, DR52 and DQw1).

Two female siblings with ulcerative colitis are reported. Both the 30-year-old elder sister and the 28-year-old younger sister developed bloody stools and diarrhea; ulcerative colitis was diagnosed by endoscopic and histologic examination of the colon. Their maternal aunt also suffered from the disease. Human leukocyte antigen analysis revealed an identical haplotype for the sisters (A24, Bw52, DR2 and DQw1), while the aunt had A24, Bw52 and DR2. The haplotypes of Japanese patients with familial ulcerative colitis are reviewed, and the role of human leukocyte antigens in this disease is discussed.

Adult↗

[Successful interferon therapy of renal cell carcinoma with tumor thrombus extending into the inferior vena cava--a case report].

It is a fact that there are few effective drugs available except for interferon for that treatment of renal cell carcinoma, and the efficacy rate of interferon is less than 10% even if multiple drug regimens are included. We have experienced a case of renal cell carcinoma in whom interferon therapy was successful in reducing the primary lesion and tumor thrombus extending into the inferior vena cava. A 57-year-old man was admitted to our department with a complaint of macroscopic hematuria. Computed tomography and magnetic resonance imaging revealed a right renal tumor and the tumor thrombus. Because of the past history of his myocardial infarction, a radical operation was considered risky. So we started interferon therapy. Four months after the start of interferon therapy, the primary lesion and the tumor thrombus markedly reduced in their size, and the clinical response was evaluated as partial response by response criteria for urological cancer treatment. Therefore, radical nephrectomy and tumor thrombectomy were performed with extracorporeal circulation. Histopathologically, necrosis and lymphocyte infiltration into the cancer cell focus were seen, and these immunologic reactions were considered at the affection of interferon. In some case, interferon therapy is a useful and safe in the treatment of the primary lesion of renal cell carcinoma, and further investigation must be studied.

Carcinoma, Renal Cell↗

Expression of platelet alpha-granule proteins in a human megakaryocytic leukemia cell line (CMK 11-5).

We investigated the expression of three platelet alpha-granule proteins, thrombospondin (TSP), von Willebrand factor (vWF), and fibrinogen (Fbg), in a human megakaryocytic cell line (CMK 11-5) by immunocytochemical staining, using the alkaline phosphatase anti-alkaline phosphatase (APAAP) complex method and immunoelectron microscopy of ultrathin-frozen sections. CMK 11-5, established from a Down's syndrome patient with acute megakaryoblastic leukemia, has characteristics closely resembling those of normal megakaryocytes. Under basal conditions, TSP expression was observed in the alpha-granules, whereas the other two proteins were not detected. When the cells were cultured with 12-o-tetradecanoylphorbol-13-acetate (TPA), the expression of TSP was enhanced and vWF was also detected, but not Fbg. Cells cultured in the presence of plasma for 24 h took up Fbg and stored it in their alpha-granules. These findings suggest that TSP and vWF are synthesized by CMK 11-5 cells, with the former being produced more rapidly than the latter, whereas Fbg is endocytosed from the plasma.

Cytoplasmic Granules↗