Biomedical subjects

K Tsubota

Publications and source records attributed to K Tsubota.

At least 145 records · Page 8Linked to original sources

PubMed1996

Subthreshold UV radiation-induced peroxide formation in cultured corneal epithelial cells: the protective effects of lactoferrin.

Acute exposure to suprathreshold ultraviolet B radiation (UV-B) is known to cause photokeratitis resulting from the necrosis and shedding of corneal epithelial cells. however, the corneal effects of low dose UV-B in the environmental range is less clear. In this study, subthreshold UV-B was demonstrated to cause non-necrotic peroxide formation in cultured corneal epithelial cells, which was attenuated by the major tear protein lactoferrin. Intracellular oxidative insults and cell viability of rabbit corneal epithelial cells (RCEC) were assessed by dual-color digital microfluorography using carboxydichlorofluorescin (CDCFH) diacetate bis (acetoxymethyl) ester, a hydroperoxide-sensitive fluoroprobe, and propidium iodide (PI), respectively. The magnitude of UV-induced oxidative insults was calibrated by concentrations of exogenously applied H2O2 which evoke compatible levels of CDCFH oxidation. Exposure of RCEC to low-dose UV-B (2.0 mJ cm-2 at 313 nm, 10.0 mJ cm-2 total UV-B) caused intracellular oxidative changes which were equivalent to those elicited by 240 microM hydrogen peroxide under the conditions of the study. The changes were dose dependent, non-necrotic, and were partially inhibited by lactoferrin (1 mg ml-1) but not by iron-saturated lactoferrin. Pretreatment with deferoxamine (2 mM) or catalase (100 U ml-1) also attenuated the UV-induced oxidative stress. The results indicate that UV-B comparable to solar irradiation levels causes significant intracellular peroxide formation in corneal epithelial cells, and that lactoferrin in tears may have a physiological role in protecting the corneal epithelium from solar UV irradiation.

Animals↗

PubMed1996

Surgical reconstruction of the ocular surface in advanced ocular cicatricial pemphigoid and Stevens-Johnson syndrome.

PURPOSE: Ocular cicatricial pemphigoid and Stevens-Johnson syndrome often cause ocular damage and blindness not amenable to surgical correction. We present a new surgical technique for reconstructing affected eyes. METHODS: Fourteen eyes of 11 patients with cicatricial keratoconjunctivitis (seven patients with cicatricial pemphigoid and four with Stevens-Johnson syndrome; average age +/- S.D., 55.5 +/- 25.4 years) were treated with a combination of allograft limbal transplantation, amniotic membrane transplantation, and tarsorrhaphy, followed every 15 minutes by artificial tears derived from the patient's blood serum. Eight eyes required concomitant penetrating or lamellar keratoplasty because of corneal opacity. RESULTS: With a mean follow-up of 143 days (range, 10 to 608 days), we achieved successful ocular surface reconstruction in 12 eyes, with minimal recurrence of symblepharon. Failure occurred in two eyes (one each in 9- and 10-year-old boys) that developed corneal infiltration and vascularization. CONCLUSIONS: A combination of allograft limbal transplantation, amniotic membrane transplantation, and tarsorrhaphy, followed by the use of serum-derived tears, can reconstruct the ocular surface in most cases. Although in this study the follow-up period was short and relatively few patients were studied, this approach appears to offer an alternative to keratoprosthesis for treating severe cicatricial keratoconjunctivitis with dry eye.

Adult↗

PubMed1996

Effects of diclofenac eye drops on corneal epithelial structure and function after small-incision cataract surgery.

PURPOSE: To investigate prospectively the effect of diclofenac sodium (DfNa) eye drops on corneal epithelial structure and function. METHODS: Seventeen patients with bilateral age-related cataract undergoing phacoemulsification combined with intraocular lens implantation were studied prospectively. After the surgery on both eyes, one eye each of these patients was assigned randomly to receive 0.1% DfNa eye drops three time daily (DfNa group), and the other eye served as control (control group). Vital stainings, tear function test, corneal sensitivity measurement, specular microscopy for corneal epithelium and endothelium, pachymetry, anterior fluorometry to measure epithelial barrier function, and laser flare-cell-metry were performed before and after surgery. RESULTS: There were no statistically significant differences between the DfNa and control groups in any measurement examined except for laser cell-flare-metry, in which the DfNa group demonstrated a significantly lower flare value at day 7 postoperatively (compare with the preoperative level of 73% +/- 41% in the DfNa group, and 130% +/- 98% in the control group, P=0.035). Epithelial cells in the DfNa group showed slight elongation and increased permeability postoperatively; however, there were no statistically significant differences with the control group. CONCLUSIONS: Administration of DfNa eye drops did not cause significant abnormalities in the corneal epithelial structure or function of patients who had undergone small-incision cataract surgery. Their safety for use in procedures such as excimer laser photorefractive keratectomy remains to be established.

Aged↗

PubMed1996

Scanning electron microscopic observation of basal cells following corneal epithelial abrasion.

By desquamating single layers of corneal epithelial cells by digitonin, we attempted to observe the basal cell layer of corneal epithelium during wound healing by scanning electron microscopy. Central corneal deepithelisation (diameter 7.0 mm) was performed on rabbit eyes. Animals were killed following healing periods of up to 14 days. Half the eyes were treated with digitonin to expose the basal cell layer, and the other half were left untreated to preserve the superficial layer. In non-wounded controls, basal cells were observed as small and columnar-shaped cells. In experimental animals, on day 3 the superficial cells as well as the underlying basal cells were elongated and enlarged. On day 7, the basal cells became columnar in shape, but remained large. Both superficial cells and basal cells returned to normal on day 14. This technique allowed us to observe the morphological reconstruction process of basal cells by scanning electron microscopy.

Animals↗

PubMed1996

Hydroxypropyl methylcellulose for the treatment of severe dry eye associated with Sjögren's syndrome.

Our purpose was to evaluate the efficacy of a new formulation of methylcellulose, preservative-free 0.5% hydroxypropyl methylcellulose (HPMC), for the treatment of dry eye. In the clinical part of our study, two groups of dry-eye patients, those with Sjögren's syndrome (SS) and those without (non-SS), were treated topically with 0.5% HPMC and evaluated for symptoms, ocular surface vital staining, tear breakup time (BUT), and tear evaporation rate from the ocular surface at 40% ambient humidity (TEROS40). In the in vivo part of the study, rose bengal uptake was measured in human conjunctival epithelial cells, which were cultured and incubated with or without 0.5% HPMC. Although symptoms improved in both groups, rose bengal and fluorescein staining and BUT improved significantly only in the SS group. TEROS40 increased for 30 min after instillation of 0.5% HPMC, but not after use of 0.1% sodium hyaluronate or saline-based artificial tears. Rose bengal uptake by cultured conjunctival epithelial cells was blocked by 0.5% HPMC. These findings suggest that 0.5% HPMC provides long coverage of and protection for the ocular surface. Patients with severe dry eye, such as in SS, are good candidates for this treatment.

Adult↗

PubMed1996

Decrease in corneal sensitivity and change in tear function in dry eye.

Our purpose was to investigate the relationship between insufficient tear secretion and decreased corneal sensitivity. We studied 59 patients with dry eye, 15 of whom had Sjögren's syndrome (SS), and 26 healthy subjects. Corneal sensitivity was measured by the esthesiometer of Cochet and Bonnet. Schirmer test with or without anesthesia, tear clearance rate, tear function index, and rose bengal and fluorescein staining were also evaluated. The mean corneal sensitivity of either dry-eye group (4.6 +/- 1.2 and 4.5 +/- 1.2 cm for non-SS and SS dry eye, respectively) was significantly lower than that of the control (5.8 +/- 0.4 cm, p < 0.001). Corneal sensitivity correlated significantly with the Schirmer values with anesthesia and the tear function index in the two dry-eye groups and the control (p < 0.05). There were significant relationships between corneal sensitivity and the rose bengal and fluorescein scores in the three groups (p < 0.05). Hyposecretion of tears in dry eye may lead to pathologic changes in corneal epithelium and a decline in corneal sensitivity. Prompt treatment of dry eye is essential to maintain a normal corneal protective mechanism.

Cornea↗

PubMed1996

Improvement of corneal sensation and tear dynamics in diabetic patients by oral aldose reductase inhibitor, ONO-2235: a preliminary study.

The mechanism in the pathogenesis of diabetic corneal disease is unclear, but aldose reductase may be involved in the corneal disease. We studied the effects of an aldose reductase inhibitor (ARI) on the ocular surface of diabetic patients. Fourteen aphakic or pseudophakic patients with diabetes were treated with orally administered ONO-2235 (150 mg/day). Corneal sensation, vital staining of ocular surface, and tear production were examined before and 3 months after the administration. After a 3-month period of oral ARI, corneal sensation recovered significantly (from 4.1 +/- 4.8 to 3.0 +/- 3.1 g/mm2; p = 0.015), with parallel improvements in rose bengal and fluorescein staining scores (p < 0.05). Tear break-up time had also improved (p = 0.003). Results of Schirmer's test (p = 0.03) and the cotton-thread test (p = 0.0001) showed significant improvement in tear production. Improvement in the dynamics of tear production may be due to an improvement in corneal sensitivity. An oral ARI can improve corneal epithelial changes caused by diabetes, probably through recovery of corneal sensation and tear production.

Administration, Oral↗

PubMed1996

Corneal temperature in patients with dry eye evaluated by infrared radiation thermometry.

AIMS: The corneal temperature change following each blink was investigated in patients with dry eye using an infrared radiation thermometer. METHODS: Twenty patients with dry eye and 20 normal controls were enrolled in this study. Subjects kept their eyes open for 10 seconds without blinking and corneal temperature was measured every second with a recently improved infrared radiation thermometer. RESULTS: In the 20 patients with dry eye, corneal temperature change after keeping the eye open for 10 seconds was 0.21 (SD 0.06) degree C while it was 0.61 (0.28) degree C in the 20 normal patients (p = 0.0001). In an exponential equation, the inclination of the slope of a patient with dry eye was smaller than the normal. The correlation coefficient was r = 0.79 (0.16) in patients with dry eye and r = 0.90 (0.07) in normal patients. The mean K value of patients with dry eye was 0.20 (0.13)/second and that of normal subjects was 0.31 (0.19)/second (p = 0.03). CONCLUSION: Findings demonstrate the usefulness of this thermometer for measuring corneal temperature in the evaluation of dry eye. Decrease in corneal temperature with each blink in patients with dry eye was smaller than in normal subjects.

Adolescent↗

PubMed1996

Non-invasive assessment of the donor corneal endothelium using ocular redox fluorometry.

AIMS: To investigate the usefulness of ocular redox fluorometry for evaluating donor corneal endothelial viability. METHODS: Corneas from 42 recipients of penetrating keratoplasty and four donor corneas were examined by ocular redox fluorometry. Autofluorescence from reduced pyridine nucleotides (PN) and oxidised flavoproteins (Fp) of the human corneal endothelium were measured non-invasively, and the PN/Fp ratio was used as a tissue metabolic indicator. Specular microscopy and electron microscopy were also performed. RESULTS: Both the quality of specular microscopic image and the PN/Fp ratio were significantly correlated with the degree of corneal endothelial damage determined by histological examination. Corneas with poor specular microscopic image showed significantly decreased PN/Fp ratio compared with corneas with good or fair specular images (p = 0.041 and 0.027, respectively). The PN/Fp ratio increased in corneas with mildly damaged endothelium but decreased in corneas with severely damaged endothelium determined by histological examination. Evaluation of corneal endothelium by combination of specular microscopy and ocular redox fluorometry showed excellent association with that of histopathological examination (p < 0.0001). CONCLUSION: Ocular redox fluorometry is useful for assessing donor corneal endothelial viability. Combination of ocular redox fluorometry and specular microscopy may increase the ability of donor cornea selection.

Adult↗

PubMed1996

Temporary corneal stem cell dysfunction after radiation therapy.

BACKGROUND: Radiation therapy can cause corneal and conjunctival abnormalities that sometimes require surgical treatment. Corneal stem cell dysfunction is described, which recovered after the cessation of radiation. METHODS: A 44-year-old man developed a corneal epithelial abnormality associated with conjunctival and corneal inflammation following radiation therapy for maxillary cancer. He experienced ocular pain and loss of vision followed by conjunctival epithelialisation of the upper and lower parts of the cornea. RESULTS: Examination of brush cytology samples showed goblet cells in the upper and lower parts of the cornea, which showed increased fluorescein permeability, and intraepithelial lymphocytes. Impression cytology showed goblet cells in the same part of the cornea. Specular microscopy revealed spindle type epithelial cells. Patient follow up included artificial tears and an antibiotic ophthalmic ointment. The corneal abnormalities resolved after 4 months with improved visual acuity without any surgical intervention, but the disappearance of the palisades of Vogt did not recover at 1 year after radiation. CONCLUSION: Radiation therapy in this patient caused temporary stem cell dysfunction which resulted in conjunctivalisation in a part of the cornea. Although limbal stem cell function did not fully recover, this rare case suggested that medical options should be considered before surgery.

Adult↗

PubMed1996

Allergic conjunctivitis and dry eye.

AIMS: Differential diagnosis of allergic conjunctivitis or dry eye is sometimes very difficult to diagnose by symptoms and clinical examination alone, especially in older patients. It was hypothesised that clinically allergic patients who were serum antigen specific IgE negative were candidates for dry eye. METHODS: Sixty patients were studied prospectively who were clinically diagnosed with allergic conjunctivitis by their itchy sensation and papilla formation of conjunctiva. They consisted of 30 serum antigen specific IgE positive and 30 IgE negative patients, with no significant differences in age. Dry eye examination and serum total IgE were performed on these two groups. RESULTS: No significant differences were seen between the two groups with regard to age (p = 0.76) and sex ratio. The antibody negative group had lower Schirmer's test scores (p = 0.002), lower tear clearance (p = 0.0001), lower tear function index (p = 0.0001), and lower serum total IgE (p = 0.04) than the antibody positive group. CONCLUSION: This study suggests that the evaluation of serum antigen specific IgE and tear dynamics are important for the differential diagnosis of patients with allergic conjunctivitis and dry eye. Clinically diagnosed allergic conjunctivitis with negative serum antigen specific and total IgE can be one form of dry eye.

Adolescent↗

PubMed1996

Increase in corneal epithelial cell size with extended wear soft contact lenses depends on continuous wearing time.

AIM: Although 1 week of continuous wearing time (CWT) is recommended for extended wear soft contact lenses (EWSCL), there have been few studies concerning the appropriateness of this or other CWTs. The current study was undertaken to examine the effect of various CWTs on the cornea by observing the corneal epithelium. METHODS: Specular microscopy was used to evaluate corneal epithelial changes induced by EWSCL in 19 myopic patients (24.0 (SD 6.7) years), divided into four groups: CWT of 0, 1, 3, and 6 days. RESULTS: The initial mean cell area was 628.2 (13.4) micron2. After 6 months this was 629.3 (28.6) micron2 for daily wear (ns), and 660.0 (40.9) micron2, 727.7 (49.6) micron2 (p < 0.01), and 815.5 (67.2) micron2 (p < 0.01) for CWT of 1, 3, and 6 days, respectively (p < 0.01). CONCLUSION: These findings indicate that the corneal epithelium changes proportionally with the CWT; the shorter the CWT, the better the epithelial morphology. This suggests that the CWT for EWSCL be minimised, so as to reduce the potential risk of contact lens related problems.

Adult↗

PubMed1996

Excimer laser photorefractive keratectomy for patients with contact lens intolerance caused by dry eye.

AIMS/BACKGROUND: To evaluate epithelial wound healing and visual outcome of excimer laser photorefractive keratectomy (PRK) performed on high myopic eyes with contact lens intolerance due to dry eye. METHODS: PRK was performed on two groups of patients with non-Sjogren's dry eye: group A (-6 D to -9.5 D, 11 patients, 17 eyes) and group B (-11.5 D to -19.5 D, 11 patients, 16 eyes) in an attempt to eliminate the use of contact lenses (CL). The intended correction was full in group A and 10 D in group B. RESULTS: Uncorrected visual acuity in group A was better than 20/40 in 12 (80.0%) of 15 eyes at 6 months and in 10 (90.9%) of 11 eyes at 1 year. Fourteen (92.8%) of 17 eyes in group A and four (25.0%) of 16 eyes in group B achieved refraction within plus or minus 1 D of the intended correction at 6 months. Re-epithelialisation was complete in 4 days, and epithelial cell area and permeability returned to the preoperative level within 1 month in all cases. All patients in group A were able to eliminate CL, whereas in group B, one patient needed spectacles for residual myopia and two patients resumed CL use because of regression. One eye with severe subepithelial scar formation and one eye with macular haemorrhage were observed in group B. CONCLUSION: Our results suggest that PRK is effective for patients with high myopia (-6 D to approximately -10 D) and CL intolerance due to dry eye. Further studies are required to improve predictability and to prevent complications in PRK for very high myopia (> -10 D).

Adult↗

PubMed1996

Immunohistological analysis of tumour growth factor beta 1 expression in normal and inflamed salivary glands.

AIM: To determine whether transforming growth factor-beta 1 (TGF-beta 1) has a pathogenetic role in disease of the salivary glands. METHODS: An indirect immunohistochemical technique was used to analyse TGF-beta 1 expression in six specimens of normal salivary gland and 23 surgical specimens. RESULTS: TGF-beta 1 was strongly expressed in the ductal epithelial cells of normal salivary gland tissues (six of six cases) and in inflammatory conditions (eight of 11 cases). In contrast, TGF-beta 1 was not detectable in ductal epithelial cells expressing HLA-DR around infiltrating CD4+ CD45RO+ activated T cells, in the salivary gland tissue of patients with Sjögren's syndrome. CONCLUSION: Because TGF-beta 1 has an essential role in the mucosal immunity of salivary glands, abnormal expression of this cytokine must be regarded as a candidate in the pathogenesis of Sjögren's syndrome.

Adult↗

PubMed1996

Retrospective survey of a link between cat and dog antigens and allergic conjuctivitis.

This retrospective 3-year study was designed to determine (a) which antigen positive patients were found in greater numbers, (b) whether the patients who were positive for cat or dog antigen-specific IgE were also positive for other antigens, and (c) whether the number of patients with allergic conjunctivitis increased during a particular time of the year. A total of 762 patients were diagnosed with allergic conjunctivitis including 107 cat-positive and/or dog-positive patients. Cat-positive patients were more prevalent than dog-positive patients, (p < 0.001). All but 2 patients were positive for other antigens, indicating a strong link between the animal antigens and other antigens. Cat and dog allergy increased in spring and early summer.

Adolescent↗

PubMed1996

Interleukin-4 and IgE in seasonal allergic conjunctivitis.

We measured interleukin-4 (IL-4) and IgE to study their presence in patients with seasonal allergic conjunctivitis. Twenty patients and 10 normal subjects were enrolled in this study, and their brush cytology samples and peripheral blood lymphocytes (PBL) were cultured for 3 or 24 h. IL-4 levels were measured using ELISA in the supernatants. Measurements of serum IgE were also performed. IL-4 was detected in 4 of 40 brush cytology samples and 10 of 40 PBL samples, but not from the controls. IL-4 positivity rate of patients was significantly higher than normal in 24-hour cultured PBL (p = 0.03). Patients' serum IgE was also significantly higher (p = 0.006). IL-4 may contribute to the development of seasonal allergic conjunctivitis.

Adolescent↗

PubMed1996

Characterization of the feline herpesvirus type 1 immediate early gene expression.

We analyzed the mechanism for feline herpesvirus type 1 (FHV-1) immediate early (IE) gene expression. We demonstrated that (i) the transcription initiation site of the FHV-1 IE transcript lies in the putative FHV-1 ICP4 binding site, (ii) the FHV-1 IE transcript is spliced to remove 906 bp intron from the leader region, (iii) cis-acting elements of the FHV-1 IE promoter map both down- and upstream of the transcription initiation site, and (iv) a deletion of a 58 bp sequence which includes the putative FHV-1 ICP4 binding site in the IE promoter resulted in significant induction of promoter activity by a FHV-1 IE gene product although the FHV-1 IE gene product slightly stimulates the FHV-1 IE promoter, indicating that the FHV-1 IE gene product down-regulates its own promoter via the region.

Alphaherpesvirinae↗

PubMed1996

Measurement of interleukin-4 and histamine in superficial cells of conjunctiva in patients with allergic conjunctivitis.

Interleukin 4 (IL-4) may play a role in the development of allergic disease. We questioned whether IL-4 related phenomenon occurred on the surface of the conjunctiva during allergic conjunctivitis. Ten patients with cedar pollen-allergic conjunctivitis and 10 patients with postsurgical conjunctivitis were enrolled in this study. Cells were collected by brush cytology from the upper palpebral conjunctiva. After the cells were cultured for 24 hours, the levels of IL-4, IgE, and histamine were measured in the supernatants. An ELISA was used for histamine and a highly sensitive sandwich ELISA for IL-4 and IgE. Conjunctival cells were also stained and fixed by May-Grunwalds stain solution. The number of superficial cells, especially lymphocytes, were compared in the two groups. The total number of cells collected by brush cytology did not differ in allergic vs., postsurgical conjunctivitis. Lymphocytes were similarly present in such specimens. The levels of IL-4 (p = 0.01) and histamine (p = 0.02) significantly increased in the specimens from patients with allergic conjunctivitis, although IgE was not detected in both groups. There was a correlation between the level of IL-4 and histamine (p = 0.0001). Conjunctival cells in allergic conjunctivitis produced a larger amount of IL-4 and histamine for cedar pollen compared to the postsurgical conjunctivitis. As with other allergic diseases, IL-4 may play a role similar to that of histamine in the development of allergic conjunctivitis.

Adolescent↗