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Biomedical subjects

K Nitta

Publications and source records attributed to K Nitta.

At least 127 records · Page 7Linked to original sources
PubMed1997

Cone electroretinogram to chromatic stimuli in myopic eyes.

The cone electroretinograms (ERGs) to different chromatic stimuli were recorded in myopic subjects. Ganzfeld color flashes under bright white background illumination were used to elicit short-wavelength-sensitive (S-), and mixed long-(L-) and middle-(M-) wavelength-sensitive cone ERGs. Nineteen subjects with mild myopia (between -3.0 and -6.0 D), 12 subjects with high myopia (greater than -6.25 D) but without chorioretinal atrophy or posterior staphyloma, and 22 age-matched normal controls were compared. The S-cone and L,M-cone b-wave amplitudes decreased progressively with increasing myopia. The amplitudes of the S-cone and the L,M-cone b-wave were significantly lower in highly myopic subjects, as compared with controls. The implicit times of both b-waves were normal in most myopic subjects. The S-cone and the L,M-cone ERGs were almost equally affected in myopic eyes. The selective reduction of the S-cone pathway in high myopia, reported previously, may not originate from the other retina.

Adolescent↗
PubMed1997

Thrombotic microangiopathy associated with alpha-interferon therapy for chronic myelocytic leukemia.

A 31-year-old man diagnosed as having chronic myelocytic leukemia (CML) developed renal insufficiency with nephrotic-range proteinuria during alpha-interferon (IFN) therapy for CML. A renal biopsy specimen showed remarkable thrombotic microangiopathic lesions resembling those of hemolytic-uremic syndrome. The patient had papules on both lower legs, and a cutaneous biopsy showed similar microangiopathic lesions in dermal and subcutaneous vessels. Although discontinuation of IFN and initiation of prednisolone therapy resulted in resolution of proteinuria, renal insufficiency persisted. These findings suggest that long-term IFN therapy can induce late-onset thrombotic microangiopathy in systemic microvessels.

Adult↗
PubMed1997

Regulated expression of endothelin converting enzymes in glomerular endothelial cells.

Endothelin converting enzyme (ECE) constitutes a potential regulatory site for the production of active mature endothelins. Two cDNAs (ECE-1 and -2) encoding ECE have recently been cloned, but the regulation of the expression of these ECE has not been clarified. In the study presented here, an attempt was made to determine whether or not glomerular endothelial cells (GEN) express ECE-1 and -2, and to learn how the expression of ECE-1 and -2 is regulated by kinase-mediated signaling systems. Ribonuclease protection assay revealed the expression of ECE-1 and -2 in cultured GEN, and the expression was increased approximately 2.5- and approximately 1.8-fold, respectively, by treatment with 10(-7) M 12-O-tetradecanocyl-phorbol-13-acetate (TPA) for 4 hours. These increases in ECE-1 and -2 expression with TPA were inhibited by cotreatment with calphostin C (10(-7) M). In contrast, 24-h treatment with 10(-7) M TPA significantly decreased the expression of ECE-1 and -2, indicating that the expression was tightly regulated by protein kinase C (PKC)-dependent mechanism(s). Actinomycin D (1 microgram/mL) abolished the TPA-induced increase of ECE-1 and -2 mRNA, whereas TPA treatment did not affect the mRNA stability of ECE-1 and -2, thus suggesting that TPA-induced increases of ECE-1 and -2 mRNA resulted from the transcriptional activation of ECE-1 and -2, gene, rather than from the increase of mRNA stability. In addition to the regulation by PKC, the effects of protein kinase A and G on ECE-1 and -2 expression were also examined. Treatment with chlorophenyl-thio cyclic AMP (200 microM) for 24 h decreased ECE-1 and -2 expression to approximately 50% and approximately 40% of the control value, respectively. 8-bromo-3', 5'-cyclic GMP also decreased ECE-1 and -2 expression to approximately 80% and approximately 25% of the control value, respectively. These results demonstrate that the expression of ECE-1 and -2 is regulated by kinase-mediated signaling systems, with the most prominent regulatory effect shown by protein kinase C.

Animals↗
PubMed1997

Effect of varying amino acid levels on protein metabolism in nephrotic rats during total parenteral nutrition.

In an attempt to determine appropriate diet in nephrotic syndrome, nephrotic rats, induced by puromycin aminonucleoside, were nourished by total parenteral nutrition fluid containing the same energy, but three different levels (1.65, 3.3, and 6.6%) of amino acids for 7 d. The fractional rate of total protein synthesis in the liver was determined by injecting a flooding dose of [3H]phenylalanine. The proportion of newly synthesized proteins retained and exported by the liver was estimated by injecting a tracer dose of [14C]leucine and then measuring the protein radioactivity remaining in the liver and present in the plasma after secretion was completed. Nephrotic animals synthesized more protein than control animals. Although the absolute synthesis rates of total protein in liver were increased with increasing amino acid administration, the absolute rates of synthesis of albumin were higher in the 3.3% group than in the other groups in nephrotic rats. However, kidney protein synthesis in nephrotic rats was higher in the 1.65% group than in the 3.3% group. Interestingly, the 3.3% group revealed the smallest urinary excretion of total protein and albumin. In addition, in the 3.3% group, plasma concentrations of total protein and albumin were higher, and plasma concentrations of total cholesterol and triglyceride were lower than in other groups. It was concluded that the 3.3% group, corresponding to a normal protein diet, has the greatest salutary effect on urinary protein excretion, followed by protein and lipid metabolism, in nephrotic rats. Not only protein intake but also the energy:protein ratio are important for diet therapy in nephrotic animals. The technique of total parenteral nutrition may be useful in defining the factors involved in glomerular permeability or permselectivity and intracellular protein metabolism.

Amino Acids↗
PubMed1997

Controlled Ecological Life Support System-related activities in Japan.

This article provides an overview of current CELSS-related activities in Japan. The status and future plan of the Closed Ecology Experiment Facilities (CEEF), the so-called, "Biosphere-J," are introduced. The Institute for Environment Sciences (ICE) has completed its first construction plan of the Closed Plant Experiment Facility (CPEF) and is now constructing the Closed Geo-Hydrosphere Experiment Facility (CGEF). Next, as one of the most prospective applications of CELSS technologies, introduced is the space-related CELSS research activity in the Space Environment Utilization Frontiers Joint Research Program, which was promoted by Science and Technology Agency (STA) and National Space Development Agency (NASDA) of the Japanese government to encourage the Space Station utilization activities.

Agriculture↗
PubMed1997

[Idiopathic hypertrophic cranial pachymeningitis associated with Horner's syndrome. A case report].

A 64-year-old man was admitted to our hospital for recurrence of visual disturbance and double vision experienced 1 year previously. He was alert and oriented. Bilateral light perception in a vision test, the third to the sixth cranial nerve palsies on the left side, and neck stiffness were observed. The patient exhibited left blepharoptosis, anisocoria and a left miotic pupil. After a pupillary drug test, a diagnosis of Horner's syndrome was made. Laboratory tests revealed hypoalbuminemia, elevated erythrocyte sedimentation rate, positive rheumatoid factor, and elevated p-ANCA. Examination of the cerebrospinal fluid showed increased initial pressure and pleocytosis, but its bacterial and fungal cultures were negative. Cranial magnetic resonance imaging after intravenous administration of gadolinium revealed mild brain edema and marked hypertrophy of the left tentorium cerebelli, bilateral frontal dura and falx. Marked hypertrophy of the dura accompanied by cellular infiltration was observed in biopsied dura specimens. The patient was given a diagnosis as idiopathic hypertrophic cranial pachymeningitis (IHCP). His ocular symptoms gradually improved with methylprednisolone pulse therapy and oral prednisolone. This is the first reported case of IHCP associated with Horner's syndrome. Previous anatomical findings of the cavernous sinus suggest that Horner syndrome in this patient might be due to a mechanism other than constrictive compression of the cranial nerves by the hypertrophic dura mater.

Anisocoria↗
PubMed1997

Development of intracoronary local adhesive delivery technique.

Acute coronary occlusion may occur in weak coronary atherosclerotic lesions, including dissection, ulceration or thrombus. In some cases of occlusion "bail-out" is performed by using recently developed New Devices. However, these have not yet completely solved the problem to this end, we designed a new method of coronary revascularization, the Intracoronary Local Adhesive Delivery Technique, utilizing antithrombotic and absorbable adhesive injected locally into the fragile and morbid arterial wall using a drug delivery PTCA catheter more flexible than the existing New Devices. This adhesive strengthened and hardened the lesions. In this study, we examined the efficacy of making an adhesive cylinder in arteries of similar size to the coronary, through acute animal experiments using the existing clinical adhesives and drug delivery PTCA catheters and 12 femoral arteries of adult goats. We were successful in forming firm tunnels along the inside of six arteries, infused with approximately 0.04 ml Cyanoacrylate. These tunnels were observed with intravascular ultrasound (IVUS) imaging and evaluated microscopically. These results suggest the feasibility of this method as a new approach for making synthetic resinous stents.

Absorption↗
PubMed1997

[Where is a leak point detected by "the low flow leak test" of anesthetic machines?].

"The low flow leak test" is recommended for pre-anesthetic inspection of anesthetic machines. We carried out anesthesia compression tests as a standard. Even in that case, often the low flow leak test does not meet the standard. We investigated the point where there is a leak in the anesthetic machine. Observing the leak that fluctuates each time there is detachment or attachment of the canister, the primary cause of the leak is thought to be related to the canister. It is important to carry out an inspection of the canister if the low flow leak test does not meet the standard.

Anesthesiology↗
PubMed1997

[Effects of recombinant human erythropoietin (rHuEpo) on the interactions between glomerular endothelial cells and mesangial cells: regulation of cell proliferation via endothelin (ET)-1].

To elucidate the effects of recombinant human erythropoietin (rHuEpo) on the interactions between glomerular endothelial cells (GENs) and mesangial cells (GMCs), we investigated whether or not cultured bovine GENs alter endothelin (ET)-1 secretion from bovine MCs and MC proliferate under basal or rHuEpo-stimulated conditions. Incubation for 24 hours with synthetic ET-1 stimulated MC in a dose-dependent manner. In addition, 100 pg/ml of ET-1 significantly stimulated MC proliferation after more than 12 hours incubation. Moreover, rHuEpo stimulated ET-1 secretion from GENs in a dose-dependent manner and showed less stimulation of ET-1 secretion from GMCs than GENs. DNA synthesis in both GENs and GMCs was significantly stimulated with more than 5 U/ml of rHuEpo. ET-1 secretion from GENs co-cultured with GMCs was higher than that from cultured GENs only. Conditioned medium, obtained from co-culture of GENs and GMCs, stimulated the proliferation of GMCs that were significantly inhibited with 10(-6) M approximately 10(-5) M BQ-123, a ETA receptor antagonist. These results suggest that rHuEpo directly stimulates the proliferation of GENs and GMCs, and this stimulatory effect is in part due to ET-1 secreted from these cells, especially GENs.

Animals↗
PubMed1996

Purification and some properties of hemagglutinin from the Myxomycete, Physarum polycephalum.

A new hemagglutinin was isolated from the plasmodium of Physarum polycephalum by salting out with ammonium sulphate followed by chromatography on DE-32, DEAE-Toyopearl and hydroxyapatite. This hemagglutinin, named physarumin, was purified 1000-fold over crude extracts. The molecular weight of physarumin was determined to be 22,000 by size exclusion chromatography on Bio-Gel P-60 and 8,700 by SDS-polyacrylamide gel electrophoresis. Physarumin agglutinated rabbit, guinea pig, horse and human erythrocytes. Physarumin-induced hemagglutination was inhibited by fetuin and alpha 1-acid glycoprotein, but not by commercially available mono- and disaccharides. Hemagglutinating activity was blocked by EDTA, and was restored by adding Ca2+ but not by Mg2+.

Amino Acids↗
PubMed1996

Measurements of trace contaminants in closed-type plant cultivation chambers.

Trace contaminants generated in closed facilities can cause abnormal plant growth. We present measurement data of trace contaminants released from soils, plants, and construction materials. We mainly used two closed chambers, a Closed-type Plant and Mushroom Cultivation Chamber (PMCC) and Closed-type Plant Cultivation Equipment (CPCE). Although trace gas budgets from soils obtained in this experiment are only one example, the results indicate that the budgets of trace gases, as well as CO2 and O2, change greatly with the degree of soil maturation and are dependent on the kind of substances in the soil. Both in the PMCC and in the CPCE, trace gases such as dioctyl phthalate (DOP), dibutyl phthalate (DBP), toluene and xylene were detected. These gases seemed to be released from various materials used in the construction of these chambers. The degree of increase in these trace gas levels was dependent on the relationship between chamber capacity and plant quantity. Results of trace gas measurement in the PMCC, in which lettuce and shiitake mushroom were cultivated, showed that ethylene was released both from lettuce and from the mushroom culture bed. The release rates were about 90 ng bed-1 h-1 for the shiitake mushroom culture bed (volume is 1700 cm3) and 4.1 approximately 17.3 ng dm-2 h-1 (leaf area basis) for lettuce. Higher ethylene release rates per plant and per unit leaf area were observed in mature plants than in young plants.

Air↗
PubMed1996

Selective reduction of the S cone electroretinogram in diabetes.

AIMS: To determine whether the short wavelength sensitive (S) cone electroretinogram (ERG) is selectively altered in diabetic patients with and without retinopathy. METHODS: Ganzfeld spectral flashes in the presence of bright white background illumination were used to elicit S cone ERGs is 15 non-retinopathic diabetics, 16 background retinopathic diabetics, and 16 age matched normal controls. RESULTS: The amplitude of the S cone ERG b-wave was significantly reduced in both non-retinopathic and retinopathic diabetics. An action spectrum based on equal response criteria revealed a selective loss of S cone sensitivity in diabetics. However, no significant difference was observed in the long and middle wavelength sensitive cone ERG. CONCLUSIONS: Diabetic patients showed selective reduction of the S cone ERG, which is thought to reflect changes in the outer retina.

Adult↗
PubMed1996

Clinical evaluation of carbocyclic oxetanocin G eyedrops in the treatment of herpes simplex corneal ulcers.

BACKGROUND: Acyclovir (ACV) ophthalmic ointment is effective in the treatment of herpetic keratitis. However, when applied, the ointment has an unpleasant feeling and some cases are resistant to ACV. A new antiviral compound, carbocyclic oxetanocin G (C.OXT-G) has potent anti-herpes simplex virus activity and high water solubility, so the clinical effect of C.OXT-G eyedrops on ulcerative herpetic keratitis was evaluated. METHODS: Studies were conducted on the corneal ulcers in 37 eyes of 27 patients. Patients with typical dendritic or geographic corneal ulcers were treated with 0.1% C.OXT-G eyedrops, applied five times a day, together with eyedrops of an antibiotic applied four times a day. The eyes were examined at least twice a week until the ulcers healed, and thereafter at intervals for up to 3 months. RESULTS: All of the ulcers healed, their average healing time being 4.9 (SD 2.2) (range 2 to 9) days. The ulcers in 20 of the 37 eyes were induced by the use of corticosteroid or immunosuppressive drugs, and their average healing time was 4.8 (2.3) days. No adverse drug reactions were seen during the observation period in this trial. CONCLUSION: Eyedrops containing 0.1% C.OXT-G are excellent and safe for treatment of herpes simplex corneal ulcers in humans.

Administration, Topical↗
PubMed1996

Undetectable S cone electroretinogram b-wave in complete congenital stationary night blindness.

AIMS: The short wavelength sensitive (S) cone electroretinograms (ERGs) were examined in two patients with the complete type of congenital stationary night blindness (CSNB). METHODS: Ganzfeld spectral flashes in the presence of strong white adapting fields were used to elicit the S cone ERGs. RESULTS: The S cone ERG b-wave was not detectable to short wavelength stimuli, while the mixed long (L) and middle (M) wavelength sensitive cone responses appeared normal in waveforms with normal amplitude in both patients. Both patients had normal colour vision on the Farnsworth Panel D-15. CONCLUSIONS: These ERG results indicated that the S cone system as well as rod system is more impaired in complete CSNB than the L and M cone system and that normal colour vision may not depend on a normal S cone ERG to full field stimuli.

Child↗
PubMed1996

Morphological changes in the peritoneal vasculature of patients on CAPD with ultrafiltration failure.

Vascular changes in the peritoneum were histochemically assessed in patients on continuous ambulatory peritoneal dialysis (CAPD) with ultrafiltration failure. Light microscopy showed extensive interstitial fibrosis, mesothelial denudation and vascular changes. Morphological changes in the vasculature were observed at different levels. The specific changes in the vasculature in these patients were characterized by severe fibrosis and hyalinization of the media of venules. Immunofluorescence microscopy revealed extensive deposition of such extracellular matrices as type IV collagen and laminin in the vascular wall. Electron microscopy revealed a significant increase in collagenous fibers and degeneration of smooth muscle cells in the media. However, the endothelial cells at the levels of vasculature affected were relatively well preserved. These pathological alterations in the vasculature in CAPD patients with ultrafiltration failure suggest that certain toxic factors, such as a high osmolar dialysate or low pH of dialysate, had affected the peritoneal vasculature from the adventitial side rather than the endothelial side. These vascular changes in the peritoneum are thought to be irreversible, associated with deterioration of peritoneal function, and to cause ultrafiltration failure in the patients on long-term CAPD therapy.

Adult↗