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Biomedical subjects

T Nagano

Publications and source records attributed to T Nagano.

At least 163 records · Page 9Linked to original sources
PubMed1996

Novel detection method of nitric oxide using horseradish peroxidase.

Nitric oxide (NO) readily makes corresponding complexes not only with ferrous iron but also with ferric iron. However, NO-ferric complexes of many heme proteins were unstable, while horseradish peroxidase formed the very stable NO-ferric porphyrin complex with a shift of the Soret band of the absorption wavelength from 396.5 nm to 420.0 nm. The concentration of NO in aqueous media could be monitored by measuring the absorption changes, and the detection limit was 10 nM. The simple procedure is convenient for concentration determination of NO solution.

Calibration↗
PubMed1996

Measurement of 1268 nm emission for comparison of singlet oxygen (1 delta g) production efficiency of various dyes.

Singlet oxygen generation from laser-excited photosensitive dyes was measured directly using a sensitive near-infrared emission spectrometer to monitor the O2(1 delta g)-->O2(3 sigma -g) transition at 1268 nm. The emission intensity was proportional to both the laser power and the concentration of the dyes. The singlet oxygen producing ability of the dyes was compared with that of eosin YS as a standard in methanol. The relative efficiencies of singlet oxygen generation were determined for rose bengal, erythrosine B, phloxine B and eosin YS as 2.39, 1.73, 1.38, 1.00, respectively, while uranine showed no emission in this spectral region. Using rose bengal, erythrosine B, phloxine B and eosin YS, the efficiency of singlet oxygen generation correlated with the photobleaching reaction rate of azo-dyes by these dyes, suggesting singlet oxygen to be a species responsible for causing the photobleaching of azo-dyes. The halogen substituent effect on the efficiency of singlet oxygen generation from laser-excited photosensitive dyes was also examined systematically.

Azo Compounds↗
PubMed1996

Oxidative stress-induced increase in intracellular Ca2+ and Ca(2+)-induced increase in oxidative stress: an experimental model using dissociated rat brain neurons.

In order to study the oxidative stress-induced change in intracellular concentration of Ca2+ ([Ca2+]i) and Ca(2+)-induced oxidative stress, effects of hydrogen peroxide and ionomycin, a calcium ionophore, on rat cerebellar neurons were examined using a flow cytometer and fluorescent dyes: fluo-3 for monitoring [Ca2+]i; 2',7'-dichlorofluorescin, for reactive oxygen species; and 5-chloromethylfluorescein, for cellular nonprotein thiols. Oxidative stress induced by hydrogen peroxide dose-dependently increased [Ca2+]i and decreased the content of nonprotein thiols. Ionomycin increased oxidative metabolism and decreased the content of nonprotein thiols. Results suggest that oxidative stress induces an increase in [Ca2+]i while an increase in [Ca2+]i increases oxidative stress in neurons.

Aniline Compounds↗
PubMed1996

Peritubular myoid cells in the testis: their structure and function.

Peritubular myoid cells, surrounding the seminiferous tubules in the testis, have been found in all mammalian species, but their organization in the peritubular interstitial tissue varies by species. In laboratory rodents, including rats, hamsters and mice, only one layer of myoid cells is seen in the testis. The cells in these animals are joined by junctional complexes as are epithelial cells. On the other hand, several cellular layers exist in the lamina propria of the seminiferous tubule in the human and some other animals. Myoid cells contain abundant actin filaments which are distributed in the cells in a species-specific manner. In the rat, the filaments within one myoid cell run both longitudinally and circularly to the long axis of the seminiferous tubule, exhibiting a lattice-work pattern. The arrangement of the actin filaments in the cells changes during postnatal development, and the disruption of spermatogenesis, such as cryptorchidism, seems to affect further the arrangement of the filaments. Other cytoskeletal proteins, including myosin, desmin/vimentin and alpha-actinin, are also found in the cells. Myoid cells have been shown to be contractile, involved in the transport of spermatozoa and testicular fluid in the tubule. Several substances (prostaglandins, oxytocin, TGF beta, NO/cGMP) have been suggested to affect the contraction of the cell, though the mechanisms of the contraction are still unknown. Recent in vitro studies have demonstrated that the cells secrete a number of substances including extracellular matrix components (fibronectin, type I and IV collagens, proteoglycans) and growth factors (PModS, TGF beta, IGF-I, activin-A). Some of these substances are known to affect the Sertoli cell function. Furthermore, it has been reported that myoid cells contain androgen receptors and are involved in retinol processing. Considering all this, it is evident that peritubular myoid cells not only provide structural integrity to the tubule but also take part in the regulation of spermatogenesis and the testicular function. Their precise roles, however, remain to be solved.

Actins↗
PubMed1996

Myofibroblasts in the lamina propria of human semi-niferous tubules are dynamic structures of heterogeneous phenotype.

Myofibroblasts of the lamina propria of human seminiferous tubules were studied in testes having normal or slightly reduced spermatogenesis by means of electron microscopy, confocal laser microscopy and immunocytochemistry. Myofibroblasts are large, flat individual cells braced in a network of microfibrils and collagen fibrils in the tubular wall. They are arranged in discontinuous cell layers with interposed layers of an extracellular matrix. Myofibroblasts of the lamina propria exhibit an unique cell shape with the peripheral cytoplasm split up in two or more layers. After FITC-phalloidin staining and by means of confocal laser microscopy, actin filaments of variable orientation are visible in their cytoplasm. The thickness and preferential direction of actin filaments differ in the outer and innermost cell layers. The myofibroblasts express both antigens of smooth muscle cells (alpha-smooth muscle actin, pan-actin, desmin, GB 42, smooth muscle myosin), and of connective tissue cells (vimentin, fibroblast surface protein). The variable expression of these antigens evidenced the existence of different phenotypes of myofibroblasts. Immunoreactivity for basic fibroblast growth factor and transforming growth factor beta as well as for components of the extracellular matrix indicate that these agents may be important for the phenotypic differentiation of the lamina propria cells. The detection of CNPase-and galactocerebroside-immunoreactivity in a number of lamina propria cells and some cells of the intertubular tissue gives rise to the hypothesis that components of the testicular tissue share some structural similarities with glia cells of the nervous system. Finally, immunoreactivities for the neuronal and endothelial nitric oxide synthase, soluble guanylyl cyclase, cyclic GMP, calmodulin, calcium-dependent protein kinase II and glutamate indicate that the contractility of myofibroblasts in the lamina propria of human seminiferous tubules may be in part modulated by the NO/cGMP-system.

Aged↗
PubMed1996

[Successful treatment of metastatic renal cell carcinoma with cimetidine--report of two cases].

There has been no effective therapy for metastatic renal cell carcinoma (RCC). Cimetidine has been demonstrated to block histamine mediated activation of suppressor T cells in man and in animal models, resulting in an anti-tumor immune response. We treated two patients with cimetidine for matastatic RCC. Case 1: A 61-year-old man presented with a diagnosis of metastatic lung and brain tumor of RCC. Interferon therapy was not effective, but after radiation therapy, his brain metastasis revealed partial response. He received cimetidine 800 mg orally after radiation, his lung metastasis revealed almost complete response. But he died of ischemic heart disease. Case 2: A 58-year-old woman presented with a metastatic lung tumor of RCC. We started interferon therapy. But because of general fatigue and anemia, she required discontinution of interferon therapy. So she received cimetidine 800 mg orally and her lung metastasis revealed complete response. She remained well and had no evidence of disease. Patients with metastatic renal cell carcinoma can occasionally respond to cimetidine and further investigation must be studied.

Administration, Oral↗
PubMed1996

[A case of hemolytic uremic syndrome after cadaveric renal transplantation].

We report a cadaveric renal transplant recipient suffering from hemolytic uremic syndrome (HUS). A 46-year-old woman received a cadaveric renal transplantation on February 16, 1994. From the 20th postoperative day, anemia, thrombocytopenia and deterioration of graft function occurred. Graft biopsy on the 20th postoperative day indicated HUS by microthrombotic arterioglomerulopathy. Plasma exchange and 15-deoxyspergualin improved her graft function. From these clinicopathological findings, we conclude that she had HUS caused by acute humoral rejection.

Cadaver↗
PubMed1996

The expression of retinoblastoma protein in epidermis is induced by ultraviolet B exposure.

DNA damage induced by ultraviolet light (UV) can be repaired while cells are arrested in the cell cycle. Tumour suppressor gene p53 has been implicated as being involved in the G1 arrest after UV irradiation. Normal human skin from three volunteers was exposed to UVB and the expression of p53, Ki-67 and retinoblastoma gene product (pRb) was examined immunohistochemically, in addition to observation for sunburn cells. p53 protein started to be expressed at 6 h after UVB irradiation. It peaked at 12-48 h. Ki-67 expression was induced after 48 or 72 h of irradiation. pRb begun to be expressed at 24 or 48 h and peaked at 48-96 h. p53-positive cells were distributed throughout the epidermis, while Ki-67 and pRb positive cells were seen mainly at the lower epidermis. Finally, sunburn cells, which are presumably apoptotic cells, appeared at 24 h and peaked at 24-48 h and were seen at upper epidermis. The different and co-ordinated expression, although variable between individuals, indicates important roles for p53 and pRb on the maintenance of the homeostasis of the epidermis after UV irradiation.

Epidermis↗
PubMed1996

[A case of renal cell carcinoma of the native kidney following cadaveric renal transplantation].

A case of renal cell carcinoma of the right native kidney following cadaveric renal transplantation is reported. A 44-year old male underwent cadaveric renal transplantation in 1993 and had stable graft function, but he had suffered from hypertension before the renal transplantation and multiple antihypertensive medications were not effective. Abdominal computed tomography demonstrated bilateral contracted kidneys, but we could not rule out renal cell carcinoma of the right kidney, completely. Angiography of the graft artery revealed no stenosis and venous sampling suggested that plasma renin activity was increased in the left renal vein. Thus we performed bilateral native nephrectomy. Histology of the right kidney was renal cell carcinoma, clear cell subtype, grade 1, pT2, and the left kidney was end stage of renal disease. Because of high incidence of malignant neoplasia after renal transplantation, routine careful examination is quite important.

Adult↗
PubMed1995

Experimental studies on postmortem diffusion of ethanol-d6 using rats.

In an investigation of postmortem ethanol diffusion deuterium-labeled ethanol-d6 was instilled by peroral gavage immediately after death by CO into the stomach of rat carcasses which were subsequently kept for 12-72 h at 5 or 30 degrees C. The heart blood, abdominal fluid and several tissues were collected and analyzed by head space gas chromatography-mass spectrometry. Rat carcasses showed no macroscopic changes until at least 72 h at 5 degrees C, and 12 h at 30 degrees C. At 30 degrees C, slight macroscopic change was observed after 24 h, moderate change after 48 h and marked change after 72 h. In the abdomen ethanol-d6 diffused gradually into neighboring organs (hepatic left lobe, left kidney and spleen) at 5 degrees C, with ethanol-d6 reaching a peak concentration of 0.75-2.38 mg/g at 24 h. At 30 degrees C, ethanol-d6 was also detected in neighboring organs and reached a peak concentration of 1.06-2.61 mg/g at 12 h. Thereafter, the ethanol-d6 concentration in the liver, kidney and spleen decreased, with concentrations ranging from 0.30 to 0.61 mg/g at 30 degrees C and 0.05 to 1.47 mg/g at 5 degrees C at 48 h. In the femoral skeletal muscle, ethanol-d6 was not detected until 24 h or more storage at 30 degrees C and never detected at 5 degrees C. In the brain and the organs in the thoracic cavity ethanol-d6 was detected after 12 h or more at 5 or 30 degrees C. Comparison of these results of direct peroral gastric instillation with those when ethanol-d6 was injected into the stomach through a laparotomy incision suggest that the brain and thoracic cavity changes were a result of diffusion from the mouth and esophagus. After 24 h at 30 degrees C, the postmortem ethanol production (0.33-0.85 mg/g) was comparable to those in previous reports. These results indicate that the assessment of ethanol concentration in the heart blood and organs in autopsy cases must be carefully conducted in comparison with the alcohol content of the stomach.

Animals↗
PubMed1995

Postmortem degradation of administered ethanol-d6 and production of endogenous ethanol: experimental studies using rats and rabbits.

Deuterium-labeled ethanol-d6 was employed to study the metabolism and postmortem change of ethanol in putrefied organ tissues. First, 4 ml/kg body weight of 25% (w/v) solution of ethanol-d6 was administered orally to each of 15 rats. The heart blood and organs were collected 15-90 min after the administration and the ethanol-d6 was analyzed by head space gas chromatography/mass spectrometry. The ethanol-d6 concentration in the organ tissues reached its maximum at 15 min after the administration and then gradually declined, showing the same pattern as human ethanol metabolism. Ethanol-d6 (3 ml of the same solution/kg body weight) was injected into the vein of a rabbit's ear (total of 12 rabbits). The rabbit was killed with carbon monoxide 30 min after the administration and the carcass was allowed to stand for 1-4 days at 30 degrees C in a moist chamber. The concentration of ethanol-d6 decreased moderately. Postmortem ethanol and 1-propanol concentrations, in contrast, showed marked increases 2.5 days and more after sacrifice in line with the degree of putrefaction of each organ tissue including skeletal muscle. This suggests the postmortem activation of micro-organism activity. These results indicate that ethanol concentrations in cadaver tissues must be carefully assessed with due consideration of postmortem degradation and production.

1-Propanol↗
PubMed1995

Distribution of the basic fibroblast growth factor and its receptor gene expression in normal and degenerated rat intervertebral discs.

STUDY DESIGN: Using a rat spondylosis model, the distributions of cells expressing the basic fibroblast growth factor and its receptor were investigated in normal and degenerated intervertebral discs. Cell-proliferating activity in degenerated discs was also assessed. OBJECTIVES: This study was conducted to determine whether basic fibroblast growth factor is related to intervertebral disc degeneration. SUMMARY OF BACKGROUND DATA: Basic fibroblast growth factor stimulates proliferation and matrix synthesis of cultured intervertebral disc cells. METHODS: Immunohistochemistry and in situ hybridization histochemistry were conducted to detect cells with basic fibroblast growth factor-like immunoreactivity and fibroblast growth factor receptor messenger RNA, respectively. Cell-proliferating activity was evaluated by AgNOR staining. RESULTS: In degenerated discs, round chondrocytes with basic fibroblast growth factor-like immunoreactivity and fibroblast growth factor receptor messenger RNA are scattered instead of spindle-shaped cells in the normal anulus (normal anular cells), which are devoid of basic fibroblast growth factor-like immunoreactivity and fibroblast growth factor receptor messenger RNA. The proliferating activity of these chondrocytes is suggested to exceed that of normal anular cells. CONCLUSION: Basic fibroblast growth factor is suggested to promote proliferation of chondrocytes in degenerated discs in an autocrine or paracrine manner. Basic fibroblast growth factor may be related to intervertebral disc degeneration as a proliferation-stimulating factor of chondrocytes that replace normal anular cells during disc degeneration.

Animals↗
PubMed1995

Direct measurements of endothelium-derived nitric oxide release by stimulation of endothelin receptors in rat kidney and its alteration in salt-induced hypertension.

BACKGROUND: Stimulation of endothelin subtype B (ETB) receptors has been proposed to induce release of endothelium-derived nitric oxide (EDNO). METHODS AND RESULTS: To obtain direct evidence of its release and its alteration in deoxycorticosterone acetate (DOCA)-salt hypertension, EDNO released from renal vessels by ET stimulation was assayed by a highly sensitive chemiluminescence method. Kidneys were isolated from DOCA-salt and control rats, and renal perfusion pressure (RPP) and EDNO (by hydrogen peroxide-luminol chemiluminescence) in the perfusate were monitored simultaneously during perfusion of ET-1, ET-3, an ETA receptor antagonist (BQ-123), and an ETB receptor agonist (BQ-3020). In control rats, ET-1 and ET-3 dose-dependently increased both RPP and NO release. Although the vasoconstricting effects of ET-1 were greater, their NO-releasing effects were comparable. The increase in NO release by ETs was inhibited by NG-monomethyl-L-arginine. After 10(-6) mol/L BQ-123 treatment, ET-1 decreased RPP and increased NO release in control kidneys. DOCA-salt rats responded to these agents with much less NO release. BQ-3020 at up to 10(-10) mol/L caused vasodilation (RPP, 10(-11) mol/L, -5.4 +/- 1.7%, P < .01) associated with increased NO release in control kidneys (+9.0 +/- 2.7 fmol.min-1.g-1 kidney wt, P < .01). However, in DOCA-salt kidneys, BQ-3020 caused renal vasoconstriction (RPP, +5.4 +/- 2.4%, P < .01 versus control) and a much smaller NO release (+1.1 +/- 0.4 fmol.min-1.g-1 kidney wt, P < .01 versus control). Northern blot analysis revealed that renal ETB mRNA was significantly decreased in DOCA-salt rat kidneys compared with controls (0.36 +/- 0.13 versus 1.00 +/- 0.23, P < .05). CONCLUSIONS: These results suggest that ET-1 and ET-3 release EDNO via ETB receptors in renal vessels. ETB-mediated NO release was reduced in DOCA-salt rats, which may modulate renal function and thus blood pressure regulation in DOCA-salt hypertensive rats.

Animals↗
PubMed1995

Changes in the arrangement of actin filaments in myoid cells and Sertoli cells of rat testes during postnatal development and after experimental cryptorchidism.

BACKGROUND: Abundant actin filaments are present in myoid cells and Sertoli cells in the testis. In the adult rat, the filaments form a lattice arrangement within the myoid cell, and show a hexagonal pattern in the basal junctional regions of Sertoli cells. METHODS: Isolated seminiferous tubules and frozen sections were prepared from juvenile to adult Wistar rat testes, stained with FITC-conjugated phalloidin, and observed by confocal microscopy. Unilateral cryptorchidism was induced in adult rats, and seven days later, their testes were also examined. RESULTS: In the myoid cell, parallel actin filaments running circularly around the seminiferous tubules were observed at 15 and 20 days of age. Then, at 30 days, actin filaments arranged longitudinally along the tubular long axis appeared in addition to the circular bundles. A lattice arrangement of actin-filament bundles in myoid cells became obvious at 40 days, when elongated spermatids are found in the tubule. Actin filaments in the basal junctional regions of Sertoli cells did not acquire the hexagonal pattern seen in the adult testis until 30 days of age. In the cryptorchid testes, the arrangement of actin filaments in the both cells showed a remarkable change compared to the control testis; the filaments became thinner and disrupted. CONCLUSIONS: A lattice arrangement of the actin filaments in the myoid cell appear at around 30 days, before the completion of spermatogenesis. A hexagonal pattern of the filaments in the junctional regions of Sertoli cells has already developed at this age. Cryptorchidism affects the actin filaments of the both cells.

Actins↗
PubMed1995

Trends in nonmelanoma skin cancer in Japan.

We compared the prevalence of skin cancer and solar keratosis (SK) in patients who attended 26 Japanese university hospitals between 1976-1980 with those who attended between 1986-1990 to investigate whether the incidence of skin cancer has increased or not. Age-adjusted incidence rates of basal cell carcinomas (BCC) and SK, but not squamous cell carcinomas (SCC), from 1986-1990 were higher than those from 1976-1980. In addition, a population-based incidence study was conducted in Kasai City, Hyogo prefecture, to establish the frequency of skin cancer and SK. A total of 4736 people over 20 years of age were examined. Two BCC and 36 SK patients were identified clinically and histopathologically. SCC was not found. Age-adjusted incidence rates of BCC and SK per 100,000 were 16.5 and 486.1, respectively. The BCC incidence rate in Kasai City was significantly higher than the incidence of Japanese nonmelanoma skin cancer (NMSC) reported by Gordon in 1976. Further, subjects classified as skin type I showed statistically higher SK prevalence rates compared to skin types II and III. The present study indicates that the prevalences of NMSC and SK in Japanese have increased during the last three decades and that skin type I may be a risk factor for NMSC in Japanese.

Adolescent↗