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T Hikichi

Publications and source records attributed to T Hikichi.

At least 73 records · Page 4Linked to original sources
PubMed1995

[Natural outcome of idiopathic macular hole].

To ascertain the natural outcome of idiopathic macular holes, we studied 186 eyes with the disorder: stages 1 (48 eyes), 2 (30 eyes), 3 (71 eyes), and 4 (37 eyes), which were followed for over twelve months. In 11 (23%) eyes with stage 1 lesions full-thickness macular hole developed during the follow-up period, and in 12 (25%) eyes visual acuity decreased two or more Snellen lines. Twenty-five (83%) and 21 (70%) eyes with stage 2 lesions, 39 (55%) and 22 (31%) eyes with stage 3 lesions, and 7 (19%) and 5 (14%) eyes with stage 4 lesions had enlarged macular holes and decreased visual acuity during the follow-up, respectively. The present results suggest that different stages of macular holes have different natural outcomes and the treatment should be based on their stages.

Aged↗
PubMed1994

Relationship between floaters, light flashes, or both, and complications of posterior vitreous detachment.

We examined biomicroscopically the vitreous and retinal conditions of 902 consecutive symptomatic eyes (785 patients) to ascertain the relationship between floaters, light flashes, or both, and complications of posterior vitreous detachment. Of 785 patients, 785 symptomatic eyes were divided as follows: group 1, 342 eyes with floaters alone; group 2, 240 eyes with floaters and light flashes; and group 3, 203 eyes with light flashes alone. We also studied 636 asymptomatic fellow eyes. The prevalence of posterior vitreous detachment was significantly higher in groups 1 (138 of 342, 40%), 2 (214 of 240, 89%), and 3 (137 of 203, 67%) than in the asymptomatic eyes (127 of 636, 20%), in group 2 than in groups 1 and 3, and in group 3 than in group 1 (P = .01). The prevalence of retinal breaks in eyes with posterior vitreous detachment was 5% (seven of 138), 13% (27 of 214), 12% (16 of 137), and 4% (five of 127) in groups 1, 2, 3, and the asymptomatic eyes, respectively; the prevalence was significantly higher in groups 2 and 3 than in asymptomatic eyes (P = .02 and P = .04) and group 1 (P = .04 and P = .05). The prevalence of vitreous hemorrhage in eyes with retinal breaks was 71% (five of seven), 70% (19 of 27), and 6% (one of 16) in groups 1, 2, and 3, respectively. Of 117 patients with bilateral symptoms, 105 (90%) had the same symptoms and 104 (89%) had the same vitreoretinal relationship bilaterally.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1994

The vitreous in retinal arterial occlusions.

PURPOSE: To investigate whether retinal arterial occlusion induces posterior vitreous detachment (PVD). METHODS: Vitreous condition was studied retrospectively and examined on biomicroscopy in 52 eyes with retinal arterial occlusion; 50 fellow eyes served as controls. RESULTS: Of 52 eyes with retinal arterial occlusion 27 (52%) had PVD; 25 (50%) of the 50 control eyes had PVD. There was no significant difference between the two groups in prevalence of PVD. Of the 41 patients observed for more than 1 year, PVD developed in 2 (5%) patients from each group. CONCLUSION: Our findings strongly suggest that retinal arterial occlusion does not influence the development of PVD clinically.

Adult↗
PubMed1994

Cross-linking of dermal collagen induced by singlet oxygen.

Changes were studied in dermal collagen induced by singlet oxygen, which was generated by a bilirubin-photosensitized reaction. An increase in the ratio of high-molecular-weight components (beta- and r-components) against the alpha-chain of collagen after irradiation manifested in sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Sodium azide, a singlet oxygen quencher, inhibits the alteration of the molecular size by the photochemical reaction. These data suggest that chronic sunlight irradiation may contribute to cross-links of dermal collagen.

Animals↗
PubMed1993

Risk of decreased visual acuity in full-thickness idiopathic macular holes.

We studied 169 eyes of 149 patients with a full-thickness idiopathic macular hole to ascertain the risk factors of enlargement of the hole or the surrounding retinal detachment and subsequent decreased visual acuity. Eyes were divided as follows: group A, 48 eyes with no posterior vitreous detachment and a hole 400 microns or smaller; group B, 77 eyes with no posterior vitreous detachment and a hole 400 microns or larger; group C, 13 eyes with posterior vitreous detachment and a hole 400 microns or smaller; group D, 31 eyes with posterior vitreous detachment and a hole 400 microns or larger. In group A, the macular hole enlarged in 37 eyes (77%); the retinal detachment enlarged in 35 eyes (73%); and visual acuity decreased by two or more Snellen lines in 28 eyes (58%). These percentages were significantly higher than those in group B (P = .01, P = .01, and P = .01, respectively), group C (P = .02, P = .01, and P = .01, respectively), and group D (P = .01, P = .05, and P = .01, respectively). Eyes without posterior vitreous detachment with a full-thickness idiopathic macular hole 400 microns or smaller may have a greater risk of an enlarged macular hole, surrounding retinal detachment, and subsequent visual loss.

Aged↗
PubMed1993

Role of the vitreous in the prognosis of peripheral uveitis.

We studied 116 eyes with peripheral uveitis (mean follow-up, 5.0 years) to ascertain the effect of the vitreous on prognosis. At the initial examination, the prevalence of partial posterior vitreous detachment was significantly higher in eyes with macular edema (27%) than in those without (7%, P = .01). During follow-up, the prevalence of no posterior vitreous detachment initially was significantly higher in eyes that developed macular edema (78%) than in those that did not (22%, P = .01). The prevalence of no or partial posterior vitreous detachment was also significantly higher in eyes with decreased visual acuity of three or more Snellen lines (57% and 38%, respectively) compared with those with visual acuity decreases of two Snellen lines or less (21% and 11%; P = .02 and P = .01, respectively). Eyes with peripheral uveitis with vitreous adhesion may have a less favorable prognosis compared with those with complete posterior vitreous detachment.

Adolescent↗
PubMed1993

Effect of the vitreous on the prognosis of full-thickness idiopathic macular hole.

We studied 112 eyes with full-thickness idiopathic macular holes (mean follow-up period, 5.7 years) to ascertain the effect of the vitreous on prognosis. Eyes were divided as follows: group 1, 58 eyes with no posterior vitreous detachment; group 2, 25 eyes with no posterior vitreous detachment initially and development of complete posterior vitreous detachment during follow-up; and group 3, 29 eyes with complete posterior vitreous detachment. In group 1, the macular hole enlarged in 37 eyes (64%), and the surrounding retinal detachment enlarged in 29 (50%); visual acuity decreased in 20 eyes (34%) by two or more Snellen lines. These percentages were significantly higher than in group 3 (14%, 10%, and 10%; P = .01, P = .01, and P = .03, respectively). Eyes with a full-thickness macular hole with no posterior vitreous detachment may have a greater risk of enlargement of the macular hole and surrounding retinal detachment, and thus a worse prognosis than eyes with posterior vitreous detachment.

Aged↗
PubMed1993

Vitreous findings in cases of optic nerve pits and serous macular detachment.

We examined biomicroscopically the relationship between the optic nerve and the vitreous in 17 eyes of 16 consecutive patients with pits of the optic nerve that demonstrated an associated serous detachment of the macula. The posterior vitreous was attached in 15 eyes (88%); the posterior vitreous was partially detached with a vitreous strand terminating at the optic pit in two eyes (12%). Of the 15 eyes without posterior vitreous detachment, 11 (73%) had an anomalous Cloquet's canal that was markedly condensed and terminated at the margin of the pit. During ocular movement, we observed a back-and-forth movement of the anomalous Cloquet's canal and a pulsating translucent membrane that covered the pit. Our findings suggest that the intravitreal traction on the optic pit by the anomalous Cloquet's canal may have a role in the development of macular detachment.

Adolescent↗
PubMed1980

An investigation of the effects of impulse noise exposure on man: impulse noise with a relatively low peak level.

The effects of impulse noise of a relatively low peak level were examined to develop damage risk criteria for impulse noise. Eight to 13 normal male students (age: 20-24 years) were exposed to impulse noise. Peak levels of impulse noise were 100 dB (S.P.L.) and 105 dB (S.P.L.), B-duration of impulse noise being 10 ms, 50 ms, and 100 ms, and the repetition rates of impulse noise were 3 per 1 s and 1 per 3 s. Exposure time was 8 h in all exposure conditions. Exposure conditions of long B-duration induced greater TTS2 than those of short B-duration (P less than 0.05). Impulse noise exposure at a high peak level induced slightly larger TTS2 than that at a low peak level. TTS2 increased proportionally to the logarithm of the amount of impulse noise. Exposure to impulse noise induced smaller TTS2 than that of steady-state noise of an equal energy level. In addition, exposure to large amounts of impulse noise induced slightly greater urinary 17 OHCS levels than small amounts of impulse noise, and exposure to impulse noise induced smaller urinary 17 OHCS levels than steady-state noise of an equal energy level (P less than 0.05). The decreasing effect of the acoustic reflex on the acoustic energy of impulse noise was considered to be the reason for the results obtained. This experiment supported the modified CHABA Limit of Damage Risk Criteria of impulse noise proposed by the US Environmental Protection Agency.

17-Hydroxycorticosteroids↗
PubMed1977

[Effect of additives on the amination of 2-oxoglutaric acid by gamma-radiation].

The effect of added substances was studied on the yield of glutamic acid produced by gamma-ray irradiation of 2-oxoglutaric acid and ammonia in aqueous solution. The contents of amino acids in the irradiated solutions were determined with amino acids analyzer. Sodium nitrate, allyl alcohol or sodium formate was used as an added substance. The yield of glutamic acid significantly decreased by the addition of nitrate, and it was little affected by the addition of allyl alcohol. In the presence of formate the yield increased from G = 0.4 (2-oxoglutaric acid 0.05M and ammonium hydroxide 2M) to G = 1.1. As a result, it was found that hydrated electron contributes on the formation of glutamic acid, but hydroxyl radical does not. The yield showed a maximum at ca. 0.1 M ammonium hydroxide concentration. These facts indicate that NH2 radical does not contribute to the formation of glutamic acid. As a reaction mechanism, it can be explained that 2-oxoglutaric acid which had been reduced by hydrated electron reacts with ammonia.

Alcohols↗
PubMedDate not supplied

Branch retinal vein occlusion in a Japanese patient with neurofibromatosis 1.

BACKGROUND: To report an Asian patient with branch retinal vein occlusion secondary to neurofibromatosis 1. CASE: A 64-year-old woman presented with a loss of vision in her right eye of 9-month duration. A diagnosis of neurofibromatosis 1 was made. A general medical examination showed no abnormalities except the signs of neurofibromatosis 1. OBSERVATIONS: Fundus examination of the right eye revealed irregularities of the venous caliber, partial sheathing of the corresponding vein and macular edema. Multiple dilated and tortuous collateral channels and an arteriovenous communication bridged the perfused and nonperfused retina. Fundus examination of the left eye showed a tortuous vein in the temporal region of the fovea. Fluorescein angiography of the right eye confirmed delayed filling in a superotemporal artery and in the corresponding vein. The temporal region of the fovea had large areas of capillary loss. The collaterals were tortuous and mimicked a neovascularization. Fluorescein angiography of the left eye confirmed that the vein in the temporal part of the fovea was tortuous and not leaking. A diagnosis of branch retinal vein occlusion of the superotemporal vein was made. CONCLUSIONS: Neurofibromatosis 1 should be considered in the differential diagnosis of retinal vascular occlusive disease without other risk factors.

Diagnosis, Differential↗
PubMedDate not supplied

Cross-linking of vitreous collagen and degradation of hyaluronic acid induced by bilirubin-sensitized photochemical reaction.

To determine the mechanisms of vitreous liquefaction following vitreous hemorrhage, we investigated the effects of the free radicals produced by a bilirubin-sensitized photochemical reaction on collagen and hyaluronic acid (HA). Bovine vitreous collagen and HA were irradiated by visible light in the presence of bilirubin, which is produced from the degradation of hemoglobin, as a photosensitizer. Changes in molecular weight were monitored by sodium dodecyl sulfate-polyacrylamide gel electrophoresis for the collagen, and high-performance liquid chromatography for the HA. We found that free radicals caused an increase in high-molecular-weight components and insolubilization of the vitreous collagen, and a decrease in the molecular weight of HA. The changed molecular properties of the vitreous collagen could be attributed to the extensive cross-linking of the molecules. This cross-linking and the degradation of HA, both induced by the bilirubin-sensitized photochemical reaction, may contribute to vitreous liquefaction following vitreous hemorrhage.

Animals↗
PubMedDate not supplied

Abnormal vitreous structure in optic nerve pit.

A 37-year-old man presented with an optic nerve pit and serous macular detachment of the left eye. Scanning laser ophthalmoscopy revealed a cyst-like structure terminating at the pit in the premacular vitreous. During ocular movement, this structure moved vigorously and seemed to exert traction on the pit. We believe that it is part of an anomalous Cloquet's canal, and that traction on the pit may be a significant factor in the development of serous macular detachment in this patient.

Adult↗
PubMedDate not supplied

Vitreous changes after treatment of retinopathy of prematurity.

PURPOSE: To investigate the vitreous findings in patients with cicatricial retinopathy of prematurity (ROP) who underwent retinal cryopexy and/or photocoagulation during the acute phase of the disease. METHODS: Vitreous findings were evaluated in 15 patients (29 eyes) with cicatricial ROP by slit-lamp biomicroscopy and indirect ophthalmoscopy. RESULTS: The ocular examination revealed that all eyes had extensive vitreous liquefaction that affected a large segment of the vitreous. A great deal of fibrillar condensation of the vitreous was present in membrane-like vitreous fibers that traversed the vitreous cavity to the periphery of the degenerating retina. These vitreous changes were most marked in the areas in which retinal cryopexy and/or photocoagulation had been performed. Despite advanced liquefaction, the posterior cortical vitreous was not separated from the retina in any eyes. CONCLUSION: In eyes with ROP that underwent retinal cryopexy and/or photocoagulation during the acute phase of the disease, the vitreous was abnormal, which may contribute to vitreoretinal traction that eventually leads to retinal breaks and detachment.

Adolescent↗
PubMedDate not supplied

Effect of corticotropin releasing factor receptor 1 antagonist on extracellular norepinephrine, dopamine and serotonin in hippocampus and prefrontal cortex of rats in vivo.

Corticotropin releasing factor (CRF) is a major mediator of adaptive responsiveness to stress. We measured changes in extracellular concentrations of catecholamine and indoleamines in freely moving rats in response to administration of CRF1 antagonist CP-154,526 by using in vivo microdialysis. Dialysis probes were placed stereotaxically in either the hippocampus or the prefrontal cortex. We examined the response in the hippocampus or the prefrontal cortex to 32.0 mg/kg i.p. administration of CP-154,526. CP-154,526 reduced the extracellular concentration of norepinephrine (NE) from 30 min to 180 min and 5-hydroxytryptamine (5-HT) from 30 min to 60 min after injection in the hippocampus. CP-154,526 did not remarkably change dopamine (DA). There were no significant differences between CP-154,526 and vehicle in NE, 5-HT and DA in the prefrontal cortex. The present results indicate that CRF1 receptor antagonist produced a decrease in dialysate concentration of NE and 5-HT, but not DA, in the hippocampus. These results suggest that the CRH-1 receptor antagonist suppresses the release of NE and 5-HT in the hippocampus.

Animals↗