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N Miyata

Publications and source records attributed to N Miyata.

At least 109 records · Page 6Linked to original sources
PubMed1993

[Changes in 31P-MR spectroscopy in murine experimental tumor (SCC VII) after irradiation].

Changes in the phosphate metabolism of transplanted squamous cell carcinoma VII (SCC VII) tumor were studied after irradiation using in vivo 31P-magnetic resonance spectroscopy (MRS). The results were as follows. 1) Phosphocreatine (PCr), gamma-,alpha- and beta-ATP, inorganic phosphate (Pi), phosphomonoester (PME) and phosphodiester (PDE) were detected in 31P-MR spectroscopy of SCC VII solid tumor. 2) 31P-MRS parameters, including PCr, beta-ATP, PCr/Pi, beta-ATP, beta-ATP/Pi and pH, increased after irradiation, then decreased with tumor regrowth. 3) Pi, PME and PDE decreased transiently after irradiation, and thereafter increased gradually. 4) PCr/Pi showed the most remarkable increase (p < 0.05) of all parameters following irradiation. Therefore, it may be employed as a therapeutic index in radiation therapy. Because PCr/Pi decreased again after irradiation prior to regrowth of tumor, it may be used to predict tumor regrowth. From these results, it was suggested that 31P-MRS was useful for monitoring the effects of radiation therapy, and regrowth after irradiation.

Animals↗
PubMed1993

Effects of VA-045, a novel apovincaminic acid derivative, on isolated blood vessels: cerebroarterial selectivity.

We investigated the effects of VA-045, an apovincaminic acid derivative, on isolated blood vessels. VA-045 (10(-7)-10(-5) M) and vinpocetine (10(-7)-10(-5) M) inhibited the 64 mM KCl-induced and 10(-6)M norepinephrine (NE)-induced contraction of rat aortic strips. VA-045 (10(-7)-10(-4) M) and vinpocetine (10(-7)-10(-4) M) inhibited the activity of cyclic AMP and cyclic GMP phosphodiesterase in porcine coronary artery. VA-045 (3 x 10(-9-3 x 10(-6) M) relaxed the 64 mM KCl-induced contraction of the canine basilar artery without affecting the peripheral arteries. These results indicate that VA-045 selectively dilates canine cerebral artery, and that it may be a useful agent for the treatment of cerebrovascular diseases such as stroke.

3',5'-Cyclic-GMP Phosphodiesterases↗
PubMed1993

[Uveitis in human T-lymphotropic virus type I (HTLV-I) carriers--1. A seroepidemiological study].

A seroepidemiological study was carried out to find out if human T-lymphotropic virus type I (HTLV-I) was closely associated with uveitis in two hospitals: one in an area where HTLV-I was highly prevalent (Miyakonojo, Miyazaki) and the other in an area where HTLV-I was less prevalent (Kurume). In the highly prevalent HTLV-I area, the seroprevalence in patients with idiopathic uveitis (78/206, 37.9%) was significantly higher than in patients with non-uveitic ocular diseases (73/380, 19. 2%) or in patients with uveitis with defined etiologies (8/80, 10.0%). A more striking finding was that the seroprevalence in the younger group (20-49 years) with idiopathic uveitis in the area was 40/82 (48.8%), but only 9/114 (7.9%) in the other two reference groups. The odds of contracting idiopathic uveitis for HTLV-I infected persons was estimated at 11.0 in the younger group, and 2.0 in the older group. Similar observations were recorded even in the less prevalent area (Kurume). These data thus suggest that HTLV-I infection is a risk factor for idiopathic uveitis.

Adult↗
PubMed1993

[Uveitis in human T-lymphotropic virus type I (HTLV-I) carriers--2. An analysis of clinical features].

The clinical features of human T-lymphotropic virus type (HTLV-I) uveitis, an idiopathic uveitis in HTLV-I seropositive patients, were analyzed in a hospital located in an area where HTLV-I was endemic (Miyakonojo, Miyazaki). A total of 61 patients (25 males and 31 females) with HTLV-I uveitis were the subjects of the analysis. Intermediate uveitis with moderate to severe vitreous opacities accompanied by mild iritis and retinal vasculitis was the most characteristic feature, and was observed in the majority of the patients (66% of all or 84% in young adult patients between 20 and 49 years of age). The uveitis affected one eye in 57% and both eyes in 43% of the patients, with subacute onset of floaters and foggy vision. The uveitis responded well to therapy with topical or systemic corticosteroids, but recurred in many cases. A significant number of patients (15% of all and 25% of female patients) had a previous history of Graves' disease with hyperthyroidism.

Adult↗
PubMed1993

[Uveitis in human T-lymphotropic virus type I (HTLV-I) carriers--3. A molecular biological study].

The presence of proviral DNA of human T-lymphotropic virus type I (HTLV-I) in the inflammatory cells in the aqueous humor was examined by polymerase chain reaction. The proviral DNA was detected in all the tested patients (n = 9) with HTLV-I uveitis. On the other hand, the provirus was not detected in 2 out of 3 HTLV-I seropositive patients with other types of uveitis, i.e., Behçet's disease, toxoplasmosis and Vogt-Koyanagi-Harada's disease. None of the 11 seronegative patients with other types of uveitis or senile cataract had proviral DNA in the aqueous humor. Thus, the fact that HTLV-I-infected cells were present in the aqueous humor of all HTLV-I uveitis patients suggests significant involvement of HTLV-I in the pathophysiology of the uveitis.

Aqueous Humor↗
PubMed1992

Uveitis associated with human T-cell lymphotropic virus type I.

Seroepidemiologic, clinical, and virologic studies were performed to determine whether human T-cell lymphotropic virus type I was closely associated with uveitis in two hospitals. One hospital was in an endemic area of the virus (Miyakonojo, Miyazaki) and the other hospital was in a less endemic area (Kurume). In the endemic area, the seroprevalence of the virus in patients with uveitis without defined causes (35.4%, 62 of 175 patients) was significantly higher than that in patients with nonuveitic ocular diseases (16.1%, 42 of 261 patients), or in patients with uveitis with defined causes (10.3%, eight of 78 patients). The seroprevalence in younger patients (20 to 49 years of age) with uveitis without defined causes in the area was 44.8% (30 of 67 patients), whereas it was only 9.3% (ten of 107 patients) in the other two groups. A similar observation was recorded even in the less endemic area (Kurume). Because the seroprevalence of the virus in the general population is known to be low in younger patients and to increase with age, these findings were interpreted to indicate that the association of human T-cell lymphotropic virus type I with uveitis was significant. Most patients, particularly those aged 20 through 49 years, had an intermediate uveitis characterized by a moderate inflammation in the vitreous body accompanied by an iritis and retinal vasculitis. The ocular symptoms in the patients differed from those of other types of uveitis common in Japan (Behçet's disease, Vogt-Koyanagi-Harada's disease, and toxoplasmosis, for example).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Induction of colon adenocarcinomas in CD rats and lung adenomas in ICR mice by 6-nitrochrysene: comparison of carcinogenicity and aryl hydrocarbon hydroxylase induction in the target organs of each species.

Species and organ specificity of 6-nitrochrysene (6-NC)-induced carcinogenicity and the potential correlation with aryl hydrocarbon hydroxylase (AHH) induction in the target organs were investigated in both sexes of ICR mice and CD rats. Animals received total 6-NC doses of 1.4 mumol/mouse and 14.8 mumol/rat. The first i.p. injection was performed within 24 h of birth, then the animals were subjected to 3 and 5 weekly injections in the mouse and rat cases, and the survivors were sacrificed at weeks 24 and 32, respectively. Adenocarcinomas and dysplasias and/or adenomas of the colon in rats and lung adenomas in mice were observed in animals treated with 6-NC. However, no such lesions were observed in animals treated with the vehicle dimethyl sulfoxide alone. AHH activities in the lung, colon, and liver of each animal after treatment with 6-NC or dimethyl sulfoxide were also investigated. Six-week-old animals received a single 6-NC injection i.p. at the dose of 0.8 mumol/mouse or 8.0 mumol/rat. Animals were sacrificed on day 1 or 7 following injections, when AHH levels were measured. The results indicated enzyme levels in all these organs to be elevated by 6-NC treatment, the induction rate in the mouse lung being the highest. These results showed that 6-NC is carcinogenic for the colon of rats, as well as the lung of mice, and that it also induces AHH activity in both target and nontarget organs.

Adenocarcinoma↗
PubMed1992

Reduction properties of nitrated naphthalenes: relationship between electrochemical reduction potential and the enzymatic reduction by microsomes or cytosol from rat liver.

The nitroreductase activities of rat liver microsomes and cytosol towards various nitrated naphthalenes (1-, 2-mononitro-, 1,3-, 1,5-, 1,7-, 1,8-dinitro-1,3,5- and 1,3,8-trinitronaphthalenes) were characterized as follows. (1) The rates of reduction of nitrated naphthalenes in either microsomal or cytosolic incubation were found to increase in the order of trinitro- > dinitro- > mono-nitronaphthalene, although, in the case of microsomal nitroreduction, trinitronaphthalenes were reduced more rapidly than in cytosol. (2) The effective cofactors, electron donors, in the nitroreduction of nitrated naphthalenes in cytosol were NADH and hypoxanthine, but not NADPH. (3) The nitrated naphthalenes with a nitro group at a beta-position appear to be more easily reduced among the various isomers. The cytosolic nitroreductase activities towards the nitrated naphthalenes were closely related to the single-electron reduction potentials measured by cyclic voltammetry and hence, there was a good relationship between the logarithm of nitroreductase activities and the electrochemical reduction potentials. In microsomes, nitroreductase activities were rather less well related to electrochemical reduction potentials.

Animals↗
PubMed1992

Functional changes in vascular smooth muscle and endothelium of arteries during diabetes mellitus.

To investigate the influence of diabetes mellitus on the responsiveness of the vascular smooth muscle, the effects of various vasoactive agents on the reactivity of the vascular smooth muscle from diabetic animals have been undertaken, focusing on the functional changes in the endothelium, alpha-adrenoceptors, beta-adrenoceptors, voltage-dependent Ca(2+)-channels, receptor-operated Ca(2+)-channels, phosphatidylinositol turnover and potassium channels. Among the functional changes, it is a common phenomenon that decreases in acetylcholine-induced production of cyclic GMP are due to the attenuation of release of endothelium-derived relaxing factor through an impairment of endothelium; this observation was found in both rats and rabbits with diabetes mellitus. These functional changes in diabetes may be responsible for the vascular complications such as coronary heart disease, cerebrovascular disease, and an acceleration in atherosclerosis.

Animals↗
PubMed1992

Changes in responsiveness of the aorta to vasorelaxant agents in genetically diabetic rats: a study in WBN/Kob rats.

The effects of various vasorelaxant agents on aortas from control and genetically diabetic rats were examined. The concentration-response curves for the isoproterenol (ISO)-induced relaxation of both aortic strips with and without endothelium are shifted to the right in diabetic rats. The relaxation responses of diabetic aorta to forskolin and vasoactive intestinal peptide did not differ from those of controls. The relaxation responses of diabetic aorta to cromakalim and nicorandil did not differ from those of controls. These results indirectly indicate that ISO-induced relaxation responses of the aortic strips from genetically diabetic rats decreased, and that this decreased relaxation response of the strips to ISO may be due to decreased density or affinity of beta adrenoceptors on the endothelium and vascular smooth muscle.

Animals↗
PubMed1992

Mutagenicity of nitro-azabenzo[a]pyrene and its related compounds.

The mutagenicity of nitrated benzo[a]pyrene (BP) and the related compounds, 1- and 3-nitrobenzo[a]pyrene (NBP), 1- and 3-nitro-6-cyanobenzo[a]pyrene (N-6-CBP), 1- and 3-nitro-6-azabenzo[a]-pyrene (N-6-ABP), 1- and 3-nitro-6-azabenzo[a]-pyrene-N-oxide (N-6-ABPO) and 1,6- and 3,6-dinitrobenzo[a]-pyrene (DNBP), was investigated. The mutagenic activities of 3-N-6-CBP and 3-N-6-ABP were 117 and 76 times, respectively, that of 3-NBP. In addition, 3,6-DNBP was more mutagenic than 1,6-DNBP. It is suggested that the mutagenic activation differs with the position of NO2 substitution in the chemical structure. A nitro derivative with NO2 substitution at the 3 position of the aromatic ring of BP was more mutagenic than that with the substitution at the 1 or 6 position. The reducibility of DNBPs was then determined by detecting 1- or 3-amino-6-nitrobenzo[a]pyrene (A-6-NBP), a metabolite of DNBP; 3,6- and 1,6-DNBP were reduced to 3- and 1-A-6-NBP at frequencies of 958 +/- 26 and 79 +/- 8, respectively, pmole per mg of protein, when the compound was incubated anaerobically with rat liver S9 mix at 37 degrees C for 15 min. NO2 substituted at the 3 position of the aromatic ring of BP was readily reduced by a microsome enzyme to form an amino derivative. The result suggests that these compounds have a structure-activity relationship between mutagenicity and NO2 substitution of BP.

Animals↗
PubMed1992

Postsurgical inflammation after phacoemulsification and extracapsular extraction with soft or conventional intraocular lens implantation.

A one-year prospective study was conducted in 120 patients to assess the time course of changes in intraocular inflammation after three cataract surgery procedures: planned extracapsular extraction with poly(methyl methacrylate) (PMMA) intraocular lens (IOL) implantation (11 mm incision group), phacoemulsification with PMMA IOL implantation (7 mm incision group), and phacoemulsification with foldable silicone single-piece IOL implantation (4 mm incision group). Each group was carefully matched for patients' ophthalmologic and systemic backgrounds. Patients with hard nuclei were excluded. The degree of inflammation was evaluated by quantitating aqueous flare intensity and cell count with the laser flare-cell meter. In the early postoperative period, both aqueous flare intensity and cell count were highest in the 11 mm incision group followed, in decreasing order, by the 7 mm and 4 mm incision groups. Significant between-group differences were observed at one, two, and seven postoperative days for flare and one day through one week for cells. Both parameters in each group decreased to a similar level one month after surgery, but flare intensity in all groups remained significantly higher than that of age-matched normal controls up to six months postoperatively.

Aged↗
PubMed1992

HTLV-I uveitis: a distinct clinical entity caused by HTLV-I.

Seroepidemiological, clinical and virological studies were carried out in an HTLV-I endemic area to find out if HTLV-I caused an intraocular inflammatory disorder, uveitis. The seroprevalence in patients with uveitis without defined etiologies (62/175, 35.4%) was significantly higher than that in patients with non-uveitic ocular diseases (42/261, 16.1%) or in patients with uveitis with defined etiologies (8/78, 10.3%). Moreover, the seroprevalence in young adults (20-49 years) with uveitis without defined etiologies was 30/67 (44.8%), whereas it was only 10/107 (9.3%) in the other two groups. The uveitis in HTLV-I carriers was characterized clinically by a moderate inflammation of the vitreous body accompanied by a mild iritis and retinal vasculitis. The proviral DNA of HTLV-I was detected by polymerase chain reaction from the inflammatory cells in the anterior chamber in 9 out of 9 seropositive patients with the uveitis, but not in any of the tested patients with other types of uveitis. These data, thus, indicate that HTLV-I causes a specific type of intraocular inflammation, uveitis.

Adult↗
PubMed1992

NAD(P)H-dependent chromium (VI) reductase of Pseudomonas ambigua G-1: a Cr(V) intermediate is formed during the reduction of Cr(VI) to Cr(III).

An NAD(P)H-dependent Cr(VI) reductase (molecular weight = 65,000) was purified from a Cr(VI)-resistant bacterium, Pseudomonas ambigua G-1. Stoichiometric analysis of the enzymatic reaction showed that the enzyme catalyzed the reduction of 1 mol of Cr(VI) to Cr(III) while consuming 3 mol of NADH as an electron donor. Chromium(VI) was reduced to Cr(V) by one equivalent NADH molecule in the absence of the enzyme. Electron spin resonance analysis showed that Cr(V) species (g = 1.979) was formed during the enzymatic reduction. The amount of Cr(V) species formed was about 10 times larger than that of the nonezymatic reduction. These findings show that the Cr(VI) reductase reduced Cr(VI) to Cr(III) with at least two reaction steps via Cr(V) as an intermediate.

Chromatography, Liquid↗
PubMed1992

Age-related changes in endothelium-dependent relaxation in aorta from genetically diabetic WBN/Kob rats.

Experiments were designed to investigate the effects of aging and hyperglycemia on relaxation of the aorta for both endothelium-dependent and -independent agents in Wistar (control) and WBN/Kob (genetically diabetic) rats. The concentration of glucose in serum was elevated significantly in aged (90-92 wk) but not young (13-15 wk) WBN/Kob rats. Endothelium-dependent relaxations of both control and WBN/Kob rats to acetylcholine were reduced by aging. The relaxations induced by acetylcholine in aortic strips were significantly attenuated in both young (nondiabetic) and aged (diabetic) WBN/Kob rats, compared with those from age-matched control vessels, respectively. The concentration-response curves for sodium nitroprusside in aortic strips from both aged control and aged WBN/Kob rats were shifted to the left when compared with those from young rats, respectively. However, the maximal relaxation responses to sodium nitroprusside showed no difference among all vessels studied. The relaxations induced by sodium nitroprusside in aortic strips from both young and aged WBN/Kob rats were similar to those from age-matched control rats, respectively. The relaxations induced by atrial natriuretic peptide showed no difference among all vessels studied. In genetically diabetic rats, functional changes in endothelium occurred before elevation of the levels of glucose in the serum. Thus impaired endothelium-dependent relaxation may play an important role in the high incidence of vascular complications in diabetes mellitus.

Acetylcholine↗