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Biomedical subjects

Masakazu Yamada

Publications and source records attributed to Masakazu Yamada.

18 recordsLinked to original sources
PubMed2006

Functional visual acuity in Stevens-Johnson syndrome.

PURPOSE: To evaluate the correlation of functional visual acuity (FVA) measurement with ocular surface findings in patients with Stevens-Johnson syndrome (SJS). DESIGN: Prospective comparative study. METHODS: Sixty-nine eyes of 38 patients with chronic SJS assessed at the Tokyo Dental College, Tokyo Medical Center, and the Kyoto Prefectural University of Medicine, Department of Ophthalmology, Kyoto, Japan, were studied. Twenty eyes of 10 normal subjects and 40 eyes of 20 patients with Sjögren syndrome (SS) were also studied. Conventional Landolt visual acuity (VA) and FVA examinations and slit-lamp examinations were performed. FVA was measured continuously by the FVA measurement system during a 30-second blink-free period in one eye. The visual maintenance ratio (VMR) was calculated as follows: VMR = [(2.7 - FVA)/(2.7 - baseline VA)], where logarithm of minimal angle of resolution values of FVA were entered into the formula and 2.7 represented the lowest visual acuity in this series. Slit-lamp examinations, Schirmer test, and fluorescein vital stainings were also performed in all subjects. RESULTS: VMR was markedly lower in patients with SJS compared with patients with SS and controls. FVA values showed a relation with the presence of corneal opacity and vascularization. CONCLUSIONS: The FVA measurement system is not only a useful tool in the evaluation of dynamic VA changes, but also reflects the ocular surface clinical findings in SJS.

Adult↗
PubMed2006

Phospholipids and their degrading enzyme in the tears of soft contact lens wearers.

PURPOSE: Low tear phospholipids levels are associated with tear film instability in soft contact lens wearers. We assayed levels of phospholipids and their degrading enzyme secretory phospholipase A2 (sPLA2) both in tears and deposited on contact lenses composed of 2 hydrophilic materials after 1 day of routine use. METHODS: Polymacon (Medalist; FDA group 1, low water/nonionic) and Etafilcon A (One Day Acuvue; group 4, high water/ionic) contact lenses were worn for 12 hours by 16 experienced contact lens wearers. Phospholipids in tear fluids and deposited on contact lenses were estimated by phosphorus determination with ammonium molybdate through enzymatic digestion. Double-antibody sandwich ELISA was used to determine group IIa sPLA2 concentrations, and sPLA2 activity was assayed using 1,2-diheptanoyl thio-phosphatidylcholine as substrate. RESULTS: Phospholipids concentrations in tears with Polymacon and Etafilcon A were 186 +/- 39 and 162 +/- 33 microg/mL, respectively. The latter concentration was significantly lower than that observed in the same subjects when not wearing contact lenses (P = 0.0023). In tears, both group IIa sPLA2 concentrations and enzymatic activity remained unchanged, regardless of lens wearing. However, Etafilcon A (0.57 +/- 0.09 microg/lens) showed more group IIa sPLA2 deposition than Polymacon (0.01 +/- 0.01 microg/lens; P < 0.001). Furthermore, group IIa sPLA2 deposited on Etafilcon A but not on Polymacon lenses retained its enzymatic activity. CONCLUSION: Significant differences of group IIa sPLA2 deposition were found in the 2 lenses tested. Such deposition might induce phospholipid hydrolysis in tears and thereby promote tear film instability in hydrophilic contact lens wearers.

Adult↗
PubMed2006

Corneal penetration of simultaneously applied topical levofloxacin, norfloxacin and lomefloxacin in human eyes.

PURPOSE: This study was performed to assess the corneal penetration of three topically applied fluoroquinolones (levofloxacin, norfloxacin and lomefloxacin) in corneal buttons obtained from patients undergoing penetrating keratoplasty. METHODS: Fourteen patients received three drops each of 0.5% levofloxacin, 0.3% norfloxacin and 0.3% lomefloxacin (the standard clinically available preparations) over a 30-min interval beginning 90 mins before their scheduled keratoplasty. Corneal samples obtained from excised buttons at the time of surgery were stored at - 80 degrees until analysis. The concentration of the administered fluoroquinolones was measured using high-performance liquid chromatography. RESULTS: The mean corneal concentration of levofloxacin (4.6 +/- 3.5 microg/g, mean +/- standard deviation) was significantly higher than that of lomefloxacin (2.7 +/- 1.8 microg/g, p = 0.0018) and norfloxacin (1.3 +/- 1.2 microg/g, p = 0.00012). CONCLUSION: Levofloxacin achieves a higher mean corneal concentration than norfloxacin and lomefloxacin in the human cornea.

Administration, Topical↗
PubMed2005

Evaluation of corneal endothelial pump function with a cold stress test.

PURPOSE: This study was designed to evaluate corneal endothelial pump function with a cold-stress test. METHODS: The study group was comprised of 16 healthy volunteers (20 eyes), 12 patients with penetrating keratoplasty (15 eyes), 9 patients with decreased corneal sensitivity (9 eyes), and 7 patients with corneal endothelial anomaly (10 eyes). After measuring central corneal sensitivity, endothelial cell density, temperature, and thickness, cold stress was applied for 10 minutes and corneal temperature and thickness were measured again. RESULTS: After cooling, the average corneal temperature decreased from 34.7 degrees C to 26.0 degrees C. The degree of corneal swelling (percent increase in thickness) for the control, penetrating keratoplasty, decreased corneal sensitivity, and corneal endothelial anomaly groups was 1.25 +/- 0.89, 3.37 +/- 2.44, 4.72 +/- 2.51, and 3.40 +/- 1.92 (% +/- standard deviation), respectively. There was a negative correlation between the degree of corneal swelling and corneal sensitivity, but not endothelial cell density, temperature, or thickness. CONCLUSION: Corneal sensitivity is an effective factor in assessing endothelial pump function.

Cell Count↗
PubMed2005

[Six cases of late-onset lattice corneal dystrophy associated with gene mutations induced by the transforming growth factor-beta].

PURPOSE: To investigate mutations in the transforming growth factor beta induced (TGFBI) gene and clinical features in 6 Japanese patients who were clinically diagnosed as having late-onset lattice corneal dystrophy (LCD). METHODS: The six patients were all male, and their ages at diagnosis were 56-82 years (average +/- standard deviation, 71.8 +/- 9.8 years). Molecular genetic analysis in the TGFBI gene was performed after informed consent was obtained. Exons 11, 12, and 14 were amplified by polymerase chain reaction (PCR), and the PCR products were directly sequenced. RESULTS: One of the 6 patients had a family history of corneal problems. Thick lattice lines in the middle to deep stroma (Cases 1, 2, and 3, right eye) and whitish nodular opaque lines in the middle stroma (Cases 4, 5, and 3, left eye) were observed. One patient showed tiny nodular deposits with thin lattice lines in the middle stroma (Case 6). A heterozygous Leu527Arg mutation in the TGFBI gene was detected in 5 patients (Cases 1 to 5); and there was Asn544Ser mutation in one patient (Case 6). CONCLUSIONS: Patients with Leu527Arg mutation in the TGFBI gene showed the late-onset form of LCD with low penetration, and varied corneal appearance.

Aged↗
PubMed2004

Vitreous concentrations of triamcinolone acetonide in human eyes after intravitreal or subtenon injection.

PURPOSE: To compare vitreous concentrations of triamcinolone acetonide (TA) achieved by prior therapeutic intravitreal and subtenon injections. DESIGN: Interventional case series. METHODS: Vitreous samples were collected from patients who required vitreous surgery, six having received a subtenon injection of TA and another six, an intravitreal injection. Vitreous concentrations of TA were measured by high-performance liquid chromatography. RESULTS: Vitreous concentrations of TA after intravitreal injection were 1.22 +/- 0.24 mug/ml, significantly higher than those after subtenon injection (<0.001 mug/ml, P = .003). Vitreous concentrations of TA after subtenon injection and TA-assisted vitrectomy performed in a few patients to visualize the transparent vitreous gel were 0.20 +/- 0.11 mug/ml, an intermediate amount between these two groups. CONCLUSION: Much higher vitreous concentrations of TA after intravitreal injection than subtenon injection may accelerate therapeutic effect when intravitreal injections are given to reduce macular edema. Subtenon injections of TA may act via the sclera as opposed to the vitreous.

Aged↗
PubMed2004

Acute respiratory failure with gross hemoptysis in a patient with lymphangioleiomyomatosis as part of tuberous sclerosis complex.

A 29-year-old woman was admitted to our hospital with a 7-day history of elevated temperature to 39.5 degrees C associated with headache and nausea. She had been diagnosed with tuberous sclerosis complex 10 years earlier. Her unconsciousness progressed, and she was diagnosed as having aseptic meningoencephalitis. The next day, she had a generalized seizure with severe hemoptysis, and she suddenly fell into severe respiratory failure (PaO2/FiO2 = 76.9). Transbronchial lung biopsy revealed the findings of lymphangioleiomyomatosis. It was suggested that neurogenic pulmonary edema accompanied with venous flow obstruction by lymphangioleiomyomatosis lesions resulted in diffuse pulmonary hemorrhage with resultant gross hemoptysis accelerating to severe hypoxemia.

Adult↗
PubMed2003

Aqueous humor levels of topically applied levofloxacin, norfloxacin, and lomefloxacin in the same human eyes.

PURPOSE: To assess the relative penetration of topical eyedrops of 3 fluoroquinolones into the aqueous humor in human eyes. SETTING: Department of Ophthalmology, Sano-Kosei Hospital, Sano, Japan. METHODS: Fifty-nine cataract patients (36 women, 23 men) received 3 drops each of levofloxacin 0.5%, norfloxacin 0.3%, and lomefloxacin 0.3% in the same eye at 15-minute intervals beginning 90 minutes before cataract surgery. At the beginning of surgery, 50 microL of aqueous humor was aspirated from the anterior chamber and stored at -80 degrees C until analyzed. The drug concentrations in the samples were analyzed using high-performance liquid chromatography. RESULTS: Five patients were excluded from the study because their sample volumes were insufficient. Norfloxacin was detected in 3 patients; the mean aqueous humor level was 0.10 microg/mL +/- 0.02 (SD). Levofloxacin was detected in all cases; the mean aqueous humor level was 0.60 +/- 0.28 microg/mL (n = 54). Lomefloxacin was not detected in 10 patients; the mean aqueous humor level was 0.23 +/- 0.11 microg/mL (n = 44). CONCLUSION: Topically applied levofloxacin had better penetration into the aqueous humor than lomefloxacin and norfloxacin.

Aged↗
PubMed2003

Substance P in human tears.

PURPOSE: To determine the levels and biochemical characteristics of substance P-like immunoreactivity (SPLI) in human tears and ascertain whether substance P (SP) concentrations in tears reflect the condition of the ocular surface. METHODS: Unstimulated tears were collected with a micropipette. Tear samples were partially purified using C-18 cartridges. Levels of SPLI in purified samples were measured using an enzyme immunoassay (EIA). For biochemical characterization of SPLI, tear extracts were fractionated using high-performance liquid chromatography (HPLC); each fraction was then subjected to EIA. To determine the catabolism of SP in tears, synthetic SP was incubated in medium containing pooled tears and then analyzed using HPLC. RESULTS: The concentration of SPLI in normal human tears was 306.0 +/- 96.5 pg/mL (mean +/- SD, range 148-555 pg/mL). Levels of SPLI did not vary significantly by age or gender. Concentrations of SPLI in tears from eyes with unilateral corneal hypesthesia were lower than those in tears from contralateral healthy eyes. Diclofenac sodium eye drops reduced concentrations of prostaglandin E2 and SPLI in tears. Analysis using HPLC indicated that five different substances contributed to SPLI in tears and that SP was broken down into several fragments, including SP(8-11), by enzymes present in tears. CONCLUSIONS: Substance P is a normal component of human tears. Levels of SPLI in tears might reflect the denervated status of the ocular surface. Substance P is catabolized by degradative enzymes in tears to maintain the ocular surface by exerting the trophic effects of SP while avoiding undesirable effects.

Administration, Topical↗
PubMed2003

Periductal area as the primary site for T-cell activation in lacrimal gland chronic graft-versus-host disease.

PURPOSE: To examine immune processes in the lacrimal gland of patients with chronic graft-versus-host disease (cGVHD) by evaluating the expression of surface molecules associated with T-cell activation. METHODS: Antibodies to CD4, CD8, CD34, CD40, CD54, CD80, CD86, CD154, and HLA-DR were used for immunohistochemical analysis of lacrimal gland biopsy specimens obtained from nine patients with cGVHD and five with Sjögren's syndrome (SS). The regions of interest were further assessed by transmission electron microscopy. RESULTS: CD4(+) and CD8(+) T cells were mainly detected in the periductal areas of the glands of patients with cGVHD, but were distributed throughout the acinar areas in patients with SS. In the periductal areas of patients with cGVHD, a subpopulation of CD4(+) and CD8(+) T cells expressed the activation marker CD154. In addition, CD4(+) and CD8(+) T cells were colocalized with mononuclear infiltrates and stromal fibroblasts expressing the full component of surface molecules necessary for antigen presentation, including HLA-DR, CD54, CD40, CD80, and CD86. Electron microscopy revealed activated fibroblasts that embraced lymphocytes and macrophages with their processes. Also, there were more CD8(+) T cells in the glandular epithelia of patients with cGVHD than in those with SS. Intraepithelial T cells were attached to epithelial cells by several primitive contacts and colocalized with dead cells. CONCLUSIONS: The results strongly suggest that CD4(+) and CD8(+) T cells in the lacrimal glands of patients with cGVHD are primarily activated in the periductal area through antigenic stimulation by potent antigen-presenting cells and stromal fibroblasts, and exert various effector functions, including cytotoxic effects on glandular epithelial cells.

Adult↗
PubMed2002

Corneal endothelial degeneration in dentatorubral-pallidoluysian atrophy.

BACKGROUND: Dentatorubral-pallidoluysian atrophy (DRPLA) is an autosomal dominant spinocerebellar degeneration that exhibits a variety of neurologic manifestations. However, only a few reports have studied disturbances outside the central nervous system. We described 2 unrelated patients with DRPLA accompanied by corneal endothelial degeneration. PATIENTS AND METHODS: A 52-year-old man presented with cerebellar ataxia and dementia. Magnetic resonance imaging of the brain showed cerebellar atrophy. Dentatorubral-pallidoluysian atrophy was diagnosed because of the detection of expansion of CAG repeats at the DRPLA locus. On admission, his visual acuity was severely impaired. Specular microscopy showed decreased endothelial cell density (500 cells/mm(2)) compared with that of healthy subjects. The second patient was a 69-year-old man with cerebellar ataxia. Magnetic resonance imaging of the brain showed cerebellar and brainstem atrophy. The diagnosis of DRPLA was based on expanded CAG repeats of the DRPLA gene. Specular microscopy showed significant decrease of endothelial cell density (1506 cells/mm(2)). Reverse transcriptase-polymerase chain reaction analysis showed DRPLA gene expression in corneal endothelial cells. CONCLUSIONS: Mutant DRPLA protein may be directly associated with corneal endothelial degeneration. Corneal endothelial cell loss is an important sign of DRPLA, and the corneas of patients with DRPLA should be examined.

Aged↗
PubMed2002

Topical diclofenac sodium decreases the substance P content of tears.

OBJECTIVE: To explore the mechanism by which diclofenac sodium eyedrops exert an adverse effect on the cornea. METHODS: In 10 healthy Japanese volunteers, 0.1% diclofenac sodium solution was instilled into one eye 3 times daily for 2 weeks. Only vehicle was applied to the other eye. Tear samples were taken before drug treatment, at 2 weeks (on the final day of treatment), and at 4 weeks. Prostaglandin E(2) and substance P concentrations in tears were measured using enzyme immunoassays. RESULTS: After treatment for 2 weeks, concentrations of both prostaglandin E(2) and substance P in tears from diclofenac sodium-treated eyes had decreased significantly, and both had returned to baseline levels by 4 weeks. No significant changes were seen in prostaglandin E(2) and substance P levels in vehicle-treated eyes at any time points. CONCLUSIONS: Diclofenac sodium eyedrops concurrently reduced concentrations of prostaglandin E(2) and substance P in tears. Depletion of substance P (a pain-associated neurotransmitter) by diclofenac sodium may promote development of corneal complications.

Administration, Topical↗
PubMed2002

Rectus eye muscle paths after surgical correction of convergent strabismus fixus.

PURPOSE: To present a new surgical procedure for convergent strabismus fixus. DESIGN: Interventional case report. METHODS: A 69-year-old woman was referred to us because of esotropia of both eyes. Both eyes were fixed in a position of extreme adduction, and ocular motility was severely restricted in all directions. Magnetic resonance imaging demonstrated that the superior rectus (SR) was deviated nasally and the lateral rectus (LR) was deviated inferiorly. We performed operations for both eyes consisting of hemitranspositions of the SR and LR combined with a large recession of the medial rectus. RESULTS: Postoperatively, the patient became able to fixate in primary gaze and ocular motility markedly improved in all directions. Magnetic resonance imaging confirmed that the paths of the SR and LR were corrected. CONCLUSIONS: This surgical procedure appears to be a useful option for treating convergent strabismus fixus.

Aged↗
PubMed2002

Aqueous humor levels of topically applied levofloxacin in human eyes.

PURPOSE: To evaluate transcorneal penetration of topically applied 0.5% levofloxacin into the aqueous humor in human eyes. METHODS: Twenty cataract patients (14 females, 6 males) received 3 drops of 0.5% levofloxacin at 15 min intervals from 90 minutes before the surgery. At the beginning of the cataract surgery, 50 microL of aqueous humor was aspirated from the anterior chamber and stored at -80 degrees C until analysis. The drug concentration of the samples was analyzed using high-performance liquid chromatography. RESULTS: A mean aqueous humor level of levofloxacin was 1.00 +/- 0.48 microg/mL (mean +/- standard deviation, n = 20), ranging from 0.30 microg/mL to 2.32 microg/mL. CONCLUSIONS: The mean concentration of levofloxacin in the aqueous humor was higher than the MIC(90) values against some common pathogens of postoperative endophthalmitis, although a great degree of interpatient variability was present.

Administration, Topical↗
PubMed2002

Substance P and its metabolites in normal human tears.

PURPOSE: To determine amounts and biochemical characteristics of substance P-like immunoreactivity (SPLI) in tears of normal human subjects. METHODS: Forty-three healthy subjects (16 males and 27 females; age range, 17-80 years) participated. Ten microliters of unstimulated tears were collected with a micropipette from one eye of all subjects. Tear samples were partially purified by C-18 cartridges. SPLI concentrations in purified samples were measured by enzyme immunoassay (EIA). For biochemical characterization of SPLI, tear extracts were fractionated by high-performance liquid chromatography (HPLC). Each fraction then was subjected to EIA. To determine the metabolism of substance P in tears, synthetic substance P was incubated in medium containing pooled tears and then analyzed by HPLC with the detector set at a 210-nm wavelength. RESULTS: The SPLI concentration in normal human tears was 306.0 +/- 96.5 pg/mL (mean +/- SD; range, 148-555 pg/mL). SPLI did not significantly vary by age or gender. HPLC analysis indicated that SPLI in tears consisted of five different substances and that substance P was converted to several fragments, including SP(8-11) by enzymes present in tears. CONCLUSIONS: Substance P, a normal component of human tears, presumably is released from the nerve endings in the ocular surface and converted to fragments by degradative enzymes in tears.

Adolescent↗
PubMedDate not supplied

Secondary amyloidosis in a corneal graft.

PURPOSE: To describe a case of secondary amyloidosis that occurred in a corneal graft. METHODS: A 30-year-old Japanese woman had opacities in the corneal graft in her right eye. Slit-lamp microscopy examination demonstrated nodular, subepithelial opacities in the graft. Results of a physical examination and her past medical history were unremarkable, except for a history of a penetrating keratoplasty for keratoconus at the age of 17. Since then, the patient had worn a hard contact lens for over 10 years. The specimen obtained by keratectomy was examined histologically. RESULTS: The histologic examination revealed hyaline, and amorphous materials stained with Congo red, which were dichroic under polarized light. Transmission electron microscopy showed the characteristic fibrillar pattern of amyloid. CONCLUSIONS: This appears to be the first reported case of secondary amyloidosis in a corneal graft. A long-standing history of hard contact lens wear may play a role in the pathogenesis of this rare condition.

Adult↗
PubMedDate not supplied

Increasing ofloxacin resistance of bacterial flora from conjunctival sac of preoperative ophthalmic patients in Japan.

PURPOSE: To examine the in vitro resistance to ofloxacin of preoperative bacterial isolates from the conjunctival sac of Japanese patients. METHODS: The database of bacterial flora cultured preoperatively from the conjunctival sac of 1455 Japanese patients (1455 eyes) between 1995 and 1999 was reviewed retrospectively. RESULTS: The incidence of resistance of isolates to ofloxacin in vitro increased from 13.5% in 1995 to 32.8% in 1999. The percentage of Staphylococcus epidermidis and Staphylococcus aureus isolates resistant to ofloxacin was 19.6% and 15.0%, respectively, in 1995 and 33.7% and 28.1%, respectively, in 1999. Logistic regression analysis showed that diabetes mellitus and aging were significantly associated with ofloxacin-resistant strains of bacteria. CONCLUSION: Clinicians should be aware of the increased likelihood that conjunctival sac flora is resistant to ofloxacin, especially in elderly and diabetic patients.

Aging↗