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Biomedical subjects

T Nakagami

Publications and source records attributed to T Nakagami.

36 records · Page 2Linked to original sources
PubMed1995

[The time required topical carbonic anhydrase inhibitor (MK-507) to take effect on intraocular pressure of normal human eyes].

The effective time course of a topical carbonic anhydrase inhibitor, MK-507, on intraocular pressure (IOP) was studied in 6 normal volunteers. As a baseline study, IOP was determined and aqueous protein concentration was determined by laser flare photometry every half hour for 5 hours with the instillation of a placebo. Then, an examination with the same time course was performed on the same subjects with the instillation of 1% MK-507 or oral administration of acetazolamide at a dose of 250 mg. MK-507 lowered IOP 30 minutes after the instillation, and showed a significant reduction of IOP at 1 hour. Aqueous protein concentration increased significantly 30 minutes after the MK-507 instillation. Acetazolamide lowered IOP 30 minutes after the administration, and showed a significant reduction of IOP at one hour. Aqueous protein concentration increased significantly one hour after the acetazolamide administration. Corneal thickness, anterior chamber depth, anterior chamber volume, and serum protein concentration were not significantly changed by the drug treatment. These results suggest that the inhibition of aqueous humor production causes the rapid reduction of IOP seen in the use of MK-507 as well as acetazolamide.

Administration, Topical↗
PubMed1994

Isolation of prolylendopeptidase-inhibiting peptides from bovine brain.

The peptides inhibiting prolylendopeptidase were screened and isolated from bovine brain by monitoring the inhibition of prolylendopeptidase produced by Flavobacterium meningosepticum. The amino acid sequence of the peptide having the highest inhibitory activity was determined as Met-Pro-Pro-Pro-Leu-Pro-Ala-Arg-Val-Asp-Phe-Ser-Leu-Ala-Gly-Ala-Leu-Asn. This peptide showed the IC50 and Ki values of 38.4 and 8.6 microM, respectively, for prolylendopeptidase isolated from bovine brain.

Amino Acid Sequence↗
PubMed1993

A beneficial role of bile pigments as an endogenous tissue protector: anti-complement effects of biliverdin and conjugated bilirubin.

Bile pigments possess an anti-complement property and could be involved in tissue protection. In this study, we examined the physiological actions of bile pigments, which had been generally regarded as waste catabolites. Biliverdin inhibited complement cascade reactions in vitro, especially at the C1 step in the classical pathway at low micromolar concentrations. Further, Forssman anaphylaxis in guinea pigs, being closely associated with complement reactions, was inhibited by oral or intravenous administration of biliverdin. Conjugated bilirubin also showed an inhibitory effect on complement-dependent reactions in vitro. From these observations, we propose a hypothesis that the pigments serve as endogenous tissue protectors by multiple lines of mechanisms including antioxidant and anti-complement actions.

Anaphylaxis↗
PubMed1992

Inactivation of herpes viruses by high hydrostatic pressure.

The effects of high hydrostatic pressure on herpes simplex virus type 1 (HSV-1) and human cytomegalovirus (HCMV) were examined. Pressure at more than 300 MPa for 10 min at 25 degrees C inactivated these virions and drastically inhibited their infection to cultured cells, and at greater than 400 MPa, reduced infective titers of HSV-1 and HCMV by more than 7 and 4 logs, respectively. Electron microscopic examination illustrated coincidentally that high pressure at 300 MPa damaged the virus envelope and prevented the virus particles from binding to the cells. The findings suggest that treatment at high hydrostatic pressure is promising as a means of inactivating HSV-1, HCMV and other enveloped viruses.

Animals↗
PubMed1992

Antiviral activity of a bile pigment, biliverdin, against human herpesvirus 6 (HHV-6) in vitro.

Biliverdin (BV), a bile pigment, was examined for its antiviral activity against human herpesvirus-6 (HHV-6) in vitro. BV (10 micrograms/ml) markedly inhibited HHV-6 replication in MT-4 cells when the cells were treated during a virus adsorption period. Its antiviral effect was weakened when cells were treated after adsorption. Treatment of cells with BV (40 micrograms/ml) 3 hr after virus infection had no inhibitory effect on virus replication. Virus replication was also significantly inhibited by treatment of MT-4 cells with BV (10 micrograms/ml) before infection, while the virions were not inactivated by BV (20 micrograms/ml). Bilirubin and urobilin, metabolic derivatives of BV, showed slight inhibitory effects on virus replication in the cells. On the other hand, BV had no potent inhibitory activity in the replication of herpes simplex virus-1 or human cytomegalovirus. These observations suggest that BV could interact with MT-4 cells to inhibit an early stage of HHV-6 infection in a virus-specific manner.

Animals↗
PubMed1992

[Effects of prostaglandin E2 on intraocular pressure, anterior chamber depth and blood flow volume of the iris and the ciliary body in rabbit eyes].

The effects of prostaglandin E2 (PGE2) on intraocular pressure (IOP), anterior chamber depth, and blood flow volume of the iris and the ciliary body of albino rabbits were investigated. Swelling and marked capillary dilatation of the ciliary body were observed after topical application of PGE2. IOP increased immediately by 200 micrograms, 400 micrograms, and 1,000 micrograms of PGE2, reached a peak within 30 minutes; then decreased gradually. The anterior chamber depth decreased only at 5 and 10 minutes after 1,000 micrograms of PGE2. The blood flow volume of the iris and the ciliary body immediately increased, and kept it up for 3 hours. Changes of IOP may be associated with an increase of blood flow attendant upon capillary dilatation of the ciliary body, and an increase of aqueous outflow due to breakdown of the blood-aqueous barrier. In addition to morphological and functional changes of the ciliary body, further factors which promote vitreous volume expansion may play an essential part in the development of malignant glaucoma.

Animals↗
PubMed1991

Visual evoked potentials in macular hole.

Pattern reversal visual evoked potentials (VEPs) with checks of 50' and 12' were recorded in 15 patients with idiopathic unilateral macular hole. VEPs from the affected eyes were reduced in amplitude compared with those from the fellow eyes, especially with checks of 12' (percentage of the amplitude in the affected eye to that in the fellow eye was 86% +/- 19% with checks of 50' and 61% +/- 35% with checks of 12'). The latencies showed no statistically significant difference between the affected and the fellow eyes, although a marked interocular delay was found in a few patients. The degree of amplitude reduction and interocular delay had no relation to the size of the macular hole or visual acuity. The effects of experimental scotomata of various sizes on the VEPs, which were evaluated in nine normal subjects, were also variable among the subjects. We conclude that although the macula predominantly participates in the pattern VEP, an estimation of the extent of macular pathology from the VEP changes may be difficult because the VEP changes induced by a macular hole have wide individual variation and have no relation to the size of the hole.

Adult↗
PubMed1991

In vitro anti-human immunodeficiency virus type 1 activity of biliverdin, a bile pigment.

Biliverdin (BV) is a bile pigment having anti-allergic properties. We examined the effect of BV on human immunodeficiency virus type 1 (HIV-1) in vitro. BV completely inhibited the cytopathic effect of HIV-1 in MT-4 cells at concentrations of 22.2 micrograms/ml or more. This inhibitory effect was also observed when BV was present during the adsorption period of HIV-1. However, BV was cytotoxic to MT-4 cells at concentrations above 800 micrograms/ml. At a concentration of 66.7 micrograms/ml, BV completely inhibited syncytia formation by HIV-infected and uninfected MOLT-4 cells. Moreover, after exposure of HIV-1 particles to BV for 2 h, the infectivity of the virus was reduced in a dose-dependent manner. It is speculated that the anti-HIV activity of BV is due to direct inactivation of virions and inhibition of virus binding to target cells.

Antiviral Agents↗
PubMed1991

[A case of central retinal vein occlusion accompanied by central retinal artery occlusion].

A 81-year-old woman developed central retinal vein occlusion (CRVO) in her left eye subsequent to central retinal artery occlusion (CRAO). She noticed sudden visual loss in the left eye. At initial examination, her left visual acuity was 0.03, and only a small visual field was preserved at temporal area. The left fundus showed findings of mild non-ischemic CRVO. In addition white clouded retina was recognized at the left posterior pole which indicated CRAO. FAG showed remarkably prolonged arterial circulation, but no retinal capillary obliteration. Then retinal hemorrhage increased rapidly and her left eye developed hemorrhagic retinopathy. Two weeks after initial examination, FAG showed extensive retinal capillary obliteration. In this case it was supposed that central retinal artery occlusion due to arteriosclerosis produced ischemic capillaropathy and venous thrombosis, after which restoration of arterial circulation caused hemorrhagic retinopathy.

Aged↗
PubMed1990

Studies on medicinal resources from livestock. II. Anti-allergic effects of pig bile. (2).

Anti-allergic activities of lyophilized pig bile [( PB]) were examined in mice with picryl chloride-induced contact dermatitis (PC-CD), an experimental model of delayed-type hypersensitivity (DTH; type-IV allergy). PC-CD was markedly inhibited by an oral administration of [PB] within 4 h after but not during 8 to 16 h after challenge with picryl chloride. Anti-inflammatory activities of [PB] were also examined in acetic acid-induced mouse increased vascular permeability, hypotonic-hyperthermic lysis of rat erythrocytes and carrageenin-induced rat hind paw edema. [PB] had no effect on these models. The present study suggests that [PB] inhibits PC-CD through its immuno-modulation in the inductive phase of DTH rather than by an anti-inflammatory action.

Animals↗
PubMed1989

Studies on medicinal resources from livestock. I. Anti-allergic effects of pig bile. (1).

Anti-allergic activities of animal biles and commercially available bile acids were evaluated in experimental allergic disease models. Pig bile exhibited marked preventive effects on the models of delayed-type hypersensitivity (type IV allergy), picryl chloride-induced contact dermatitis (PC-CD) and sheep red blood cells (SRBC)-induced footpad swelling in mice. Fel ursi (dried bear gallbladder) also had an inhibitory effect on PC-CD, whereas ox bile, chicken bile and bile acids had no effect on ether of the models.

Animals↗
PubMedDate not supplied

Local ocular immunotherapy for experimental allergic conjunctivitis.

PURPOSE: We studied the efficacy of eyedrops as local ocular immunotherapy against experimental allergic conjunctivitis. METHODS: Guinea pigs were sensitized with an intraperitoneal injection of ovalbumin (OA). Three weeks after the sensitization, a low concentration (10 microg/mL) of OA eyedrops was administered once a day for 3 weeks. Six weeks after the sensitization, an allergic inflammation was provoked with 20 mg/mL of OA eyedrops. RESULTS: In conjunctival clinical scores 30 minutes after the allergen challenge, there was no significant difference between the controls and the treated group. The total number of inflammatory cells in the conjunctiva 8 hours after the allergen challenge was significantly decreased in the treated group (60.8 +/- 23.2 cells/field) compared with the control group (199.1 +/- 83.4 cells/field). Eosinophils in the conjunctiva 24 hours after the allergen challenge were also significantly decreased in the treated group (22.1 +/- 15.5 cells/field) compared with the control group (50.3 +/- 15.0 cells/field). CONCLUSIONS: In this study, local ocular immunotherapy mainly suppressed the late phase reaction of allergic inflammation. These results coincide with previous studies of immunotherapy in which a subcutaneous injection was used. Local ocular immunotherapy is effective against experimental allergic conjunctivitis.

Allergens↗
PubMedDate not supplied

Optic disc findings in normal tension glaucoma.

One hundred thirty stereo photographs of optic discs in patients with normal tension glaucoma (NTG) were reviewed in order to identify characteristics of the three following types of NTG: focal ischemic, senile sclerotic, and generalized cup enlargement. Twenty patients in each group were selected. Focal ischemic patients were more frequently women, had a higher incidence of migraine, a relatively smaller disc size, and localized superior scotoma that often threatened fixation. Senile sclerotic patients were generally elderly, had a higher incidence of surgery under general anesthesia, had more ischemic heart disease or systemic hypertension, had a small rim area, and also had extensive peripapillary atrophy as well as combined diffuse and localized visual field defects. Generalized cup enlargement patients were younger, had a relatively larger disc size and a greater incidence of purely diffuse visual field loss. Results of our study suggest that the different characteristics of the groups are related to pathogenic mechanisms specific to each group.

Aged↗
PubMedDate not supplied

Mast cells in pterygium: number and phenotype.

PURPOSE: To investigate the pathogenesis of pterygium. METHODS: The number and phenotype of mast cells were examined in excised tissue from 35 pterygia patients and compared with those in normal conjunctival specimens obtained during cataract or other intraocular surgery. RESULTS: Toluidine blue staining showed that the mean number of mast cells in the pterygia specimens was twice as high as that in the normal conjunctival tissues. Immunohistochemistry with a primary antibody to tryptase, specific for mast cells, also revealed a twofold increase in the mast cell number in the pterygia specimens compared with the normal conjunctival tissues. In the pterygia, more than 94% of the tryptase-positive mast cells were found to express chymase and c-kit. Almost all mast cells in the pterygia were tryptase-positive, chymase-positive mast cells (MC(TC)S). There was no phenotypic difference between the mast cells in the pterygia and those in the normal conjunctival tissues. CONCLUSIONS: The MC(TC)S appear not to be immune system-related and to have functions in angiogenesis and tissue remodeling. The increase in the number of mast cells caused by nonallergic stimulation may contribute to the pathogenesis of pterygium.

Antibodies, Monoclonal↗
PubMedDate not supplied

Expression of stem cell factor in pterygium.

PURPOSE: To investigate the possible role of stem cell factor (SCF) in the pathogenesis of pterygium. METHODS: The localization of SCF was examined immunohistochemically in excised tissue from 4 primary pterygia and 5 normal conjunctival specimens. RESULTS: Three of the four pterygia showed strong immunoreactivity of SCF in the subepithelial connective tissue at the cap area. This immunoreactivity was completely blocked by using a primary antibody preincubated with recombinant SCF. The SCF-positive cells were identified as a population of fibroblasts by immunostaining for vimentin and prolyl 4-hydroxylase in adjacent sections. No apparent immunoreactivity of SCF was observed in the subepithelial connective tissues in the head and body of the pterygia and in the normal conjunctiva. CONCLUSION: Stem cell factor is overexpressed in fibroblasts at the cap area of most pterygia.

Antibodies, Monoclonal↗