Search PubMed⌕ Search

Biomedical subjects

K Tsubota

Publications and source records attributed to K Tsubota.

At least 91 records · Page 5Linked to original sources
PubMed1998

Molecular cloning of feline Fas antigen and Fas ligand cDNAs.

The Fas antigen (FasA) and Fas ligand (FasL) are key molecules which mediate apoptosis. For investigation of apoptosis in cats, we isolated molecular clones of feline FasA and FasL cDNAs by using the polymerase chain reaction (PCR) method to amplify cDNAs from feline lymphoma cell lines. These feline FasA and FasL clones contained complete open reading frames encoding 314 and 280 amino acids, respectively. These feline FasA and FasL cDNA clones had structures characteristic of the tumor necrosis factor (TNF) receptor family and TNF family, respectively. The deduced amino acid sequence of feline FasA and feline FasL, respectively showed 45.0%-60.0% and 75.0%-90.0% similarity with their human, mouse and bovine counterparts. These data will be helpful for investigating the role of the FasA and FasL system in apoptosis and for studying the various diseases associated with the deregulation of apoptosis in cats.

Amino Acid Sequence↗
PubMed1998

Adenovirus-mediated gene transfer to the ocular surface epithelium.

Gene transfer to the ocular surface epithelium is of potential therapeutic value. It was determined whether a reporter gene can be introduced into the ocular surface epithelium in vitro (human cell lines), ex vivo (human tissues), and in vivo (rats) by treating with a recombinant, replication-deficient, adenovirus type 5. Human and conjunctival cell lines were cultured with various multiplicities of infection (MOI; 3.2x10(-5)-5x10(-1)) of adenovirus vector (Ad5:Adex1CAlacZ) containing the reporter gene lacZ (1.3-2.0x10(4) PFU ml-1). The ex vivo study used human corneal and conjunctival tissues obtained from an eye bank and during surgery. Non-specific upregulation of inflammatory cytokines of conjunctival epithelium infected by Ad5 was assayed and its suppression by steroids. For the in vivo study, Ad5 (5x10(5) PFU, 5-10 microliter) was applied to the eyes of 8-12-week-old cotton rats, which were enucleated 24 and 48 hr later. The maximum lacZ expression in vitro was demonstrated in the corneal epithelial cell line at 7 days (1x10(-1) MOI) and conjunctival epithelial cell line at 2 days (4x10(-4) MOI). Furthermore, lacZ was also expressed in the superficial corneal and conjunctival epithelium in the ex vivo study. IL-6, IL-8, and ICAM-1 expression from conjunctival epithelium by Ad5 was significantly inhibited by treatment with betamethasone (BM). For the in vivo study, only the conjunctival epithelium demonstrated beta-Gal activity at 24 and 48 hr after application. These data indicate that adenovirus vector is capable of directly delivering gene to the corneal and conjunctival epithelium, suggesting a variety of possible gene therapy uses. The concomitant application of steroid eye drops may avoid inflammation.

Adenoviridae↗
PubMed1998

Serum soluble Fas/APO-1 is increased in patients with primary Sjögren's syndrome.

The aim of the study was to elucidate the involvement of Fas antigen in human autoimmune disease, by analysing serum levels of soluble Fas/APO-1 protein in patients with various autoimmune diseases, including system lupus erythematosus (SLE), rheumatoid arthritis (RA), systemic sclerosis (SSc), polymyositis/dermatomyositis (PM/DM), Behçet's syndrome and Sjögren's syndrome (SjS). The levels of soluble Fas/APO-1 in sera were quantitated by a sandwich enzyme-linked immunosorbent assay. Soluble Fas/APO-1 levels were significantly increased in serum from patients with primary Sjögren's syndrome (primary SjS) compared with control subjects. However, no significant differences in soluble Fas/APO-1 levels were noted in patients with secondary Sjögren's syndrome (secondary SjS) nor in patients with any of the other autoimmune diseases. The soluble Fas/APO-1 level in primary SjS patients with extraglandular diseases was significantly higher than that in patients without extraglandular diseases. These results suggest that soluble Fas/APO-1 protein may play an important role in the pathogenesis of primary SS.

Adult↗
PubMed1998

A new surgical technique for deep lamellar keratoplasty with single running suture adjustment.

PURPOSE: To improve the technique of deep lamellar keratoplasty. METHODS: For the recipient eye, a divide-and-conquer technique was applied to deep lamellar keratoplasty. After trephinization, the recipient cornea within the trephine was divided into four quadrants to facilitate lamellar dissection at approximately 70% depth. This procedure of division was continued until the Descemet membrane was exposed in the central area. The corneal graft was placed with an adjusted single running suture. Seventeen eyes were treated with this technique. RESULTS: In 17 eyes of 15 patients, the mean visual acuity 6 months or more after deep lamellar keratoplasty was 20/52 with eyeglass correction and 20/80 without eyeglass correction. At 6 months or more after deep lamellar keratoplasty, the mean +/- SD keratometric astigmatism in 17 eyes was 3.2 +/- 2.3 diopters. CONCLUSION: This technique facilitates deep lamellar keratoplasty and prevents high or excessive astigmatism after surgery.

Astigmatism↗
PubMed1998

Viscosity-dependent fluid dynamics of eyedrops on the ocular surface.

PURPOSE: To determine whether the viscosity of eyedrops affects the distribution of the precorneal tear film. METHODS: Using a differential pachymetry map, we obtained tear film thickness in healthy volunteers before and after the instillation of nonviscous, aqueous artificial tears and a 0.3% sodium hyaluronate solution. RESULTS: The instillation of aqueous artificial tears disclosed a significant (P < .05) thickening of the superior corneal tear film compared with the inferior corneal tear film. The increase in thickness by 0.3% sodium hyaluronate solution was uniform, with no differences between the superior and inferior cornea. CONCLUSIONS: Aqueous artificial tears caused an uneven thickening of the precorneal tear film, with most of the thickening observed at the superior cornea. Lower sections of the cornea may benefit less from the instillation of nonviscous solutions.

Cornea↗
PubMed1998

Real-time telemedicine in the clinical assessment of the ocular surface.

PURPOSE: To report the feasibility of real-time video and audio transmission of slit-lamp images of the eye using conventional telephone systems. METHOD: We analyzed the feasibility and benefits of telemedicine in the diagnosis and follow-up of ocular surface disorders in referral patients using a real-time audio-video system that functions through integrated services digital network lines at a transmission speed of 384 kilobytes per second. RESULTS: Real-time slit-lamp images obtained through integrated services digital network lines offered satisfactory visual resolution of the ocular surface for the diagnosis and follow-up of ocular surface and corneal disease, while simultaneous audio transmission allowed for direct communication with the patient and attending physician when necessary. CONCLUSION: Telemedicine using conventional telecommunication infrastructures offers sufficient information for the diagnosis and follow-up of ocular surface disorders in referral patients.

Computer Communication Networks↗
PubMed1998

Allergic conjunctivitis as a risk factor for regression and haze after photorefractive keratectomy.

PURPOSE: To analyze the relation between allergic conjunctivitis and the results of photorefractive keratectomy performed with an excimer laser in myopic eyes. METHODS: Fifty-seven myopic eyes in 57 Japanese patients were classified into three groups: a normal group (30 eyes of 30 patients), a treatment group composed of eyes with allergic conjunctivitis that were treated with fluorometholone and cromolyn sodium eyedrops from month 3 until the end of the 12- to 18-month follow-up period (16 eyes of 16 patients), and a no-treatment group composed of eyes with allergic conjunctivitis that received no allergic treatment until the end of the follow-up period (11 eyes of 11 patients). Preoperative and postoperative examinations included evaluation of corrected and uncorrected visual acuity and grading of corneal haze. RESULTS: In the no-treatment group, the mean corneal haze score +/- SD of 0.8 +/- 0.98 was significantly greater than the normal group score of 0.38 +/- 0.49 (P = .02). There was no significant difference in the haze score between the treated and normal groups. A refractive outcome of +/- 1 diopter was obtained in 30 (100%) of the 30 patients in the normal group, 15 (93.8%) of 16 patients in the treatment group, and four (36.4%) of the 11 patients in the no-treatment group. Visual acuity was 20/40 or better after photorefractive keratectomy in 30 patients (100%) in the normal group, 15 patients (93.8%) in the treatment group, and six patients (54.5%) in the no-treatment group. CONCLUSION: These findings suggest that untreated allergic conjunctivitis is a significant risk factor for haze and myopic regression after photorefractive keratectomy.

Adult↗
PubMed1998

Meibomian gland dysfunction in patients with Sjögren syndrome.

OBJECTIVE: Changes in the ocular surface of patients with Sjögren syndrome (SS) often are more severe than those in patients with dry eye without SS. This study was conducted to investigate the possible involvement of meibomian gland dysfunction in SS-related ocular surface abnormalities. DESIGN: A nonrandomized, prospective, clinical study. PARTICIPANTS: Twenty-seven eyes of 27 consecutive patients with SS (SS group) were studied. Twenty-nine eyes of age- and gender-matched non-SS patients with aqueous tear deficiency (non-SS group) were examined as control subjects. INTERVENTION: Changes in the ocular surface, tear function, and meibomian gland were examined. MAIN OUTCOME MEASURES: Tear evaporation rate, meibomian gland expression, and meibography were measured. RESULTS: Fluorescein and rose bengal staining scores were significantly higher in the SS group than in the non-SS group (P = 0.0001). Evaporation of tears was increased significantly in the SS group compared with the non-SS group. There were no significant differences in the rate of tear production between the SS and non-SS groups. Meibography showed that 11 (57.9%) of 19 eyes in the SS group had gland dropout (i.e., histologic destruction of meibomian glands) in more than half of the tarsus. The incidence was significantly higher than that in the non-SS group (5 [18.5%] of 27 eyes; P = 0.005). CONCLUSIONS: The results of this study indicate that destruction of meibomian glands and an increase in tear evaporation often are associated with changes in the ocular surface in patients with SS. Severe ocular surface changes in patients with SS may be attributed, in part, to the meibomian gland dysfunction.

Eyelid Diseases↗
PubMed1998

Tear dynamics and dry eye.

Tears undergo four processes: production by the lacrimal gland, distribution by blinking, evaporation from the ocular surface and drainage through the nasolacrimal duct. Abnormalities in any of these steps can cause dry eye. There are two kinds of tear production, basic and reflex, which can be distinguished from each other by the Schirmer test with nasal stimulation. Reflex tearing is important because it supplies such essential components as EGF and vitamin A, whose deficiency may cause squamous metaplasia. There is no reflex tearing in Sjogren's syndrome because of destruction of the lacrimal gland. In cases of diminished or absent reflex tearing, topical autologous serum is the treatment of choice. Even when there is adequate tear production, insufficient distribution, such as occurs with the decreased blinking associated with the use of video display terminals (VDT), may cause dry eye. Any process or activity that suppresses blinking interferes with tear distribution. Tear evaporation increases under certain conditions and in some diseases. When the exposed ocular surface area is increased, such as in VDT work, tear evaporation increases. Meibomian gland dysfunction (MGD) also causes increased tear evaporation by altering the quality of the oily layer in tears. Tear evaporation can be suppressed by using a warm compresser or a humidifier, narrowing the palpebral fissure, or wearing protective eyeglasses. The tear clearance rate is measured by fluorescein dye dilution in the conjunctiva. When the tear clearance is low, inflammatory cytokines or preservatives accumulate in the conjunctival sac, resulting in ocular surface diseases. Frequent use of artificial tears without preservative is the key treatment. A differential diagnosis of the abnormalities of tear dynamics can give us a proper understanding of the pathogenesis of dry eye. With this knowledge, we can formulate an efficient therapeutic approach.

Blinking↗
PubMed1998

Pirfenidone induces intercellular adhesion molecule-1 (ICAM-1) down-regulation on cultured human synovial fibroblasts.

Pirfenidone has been shown to modify some cytokine regulatory actions and inhibit fibroblast biochemical reactions resulting in inhibition of proliferation and collagen matrix synthesis by fibroblast. We have investigated the effect of pirfenidone on the expression of cell adhesion molecules. The synovial fibroblasts were treated with IL-1alpha in the presence or absence of pirfenidone (range 0-1000 microM), and assayed for the expression of adhesion molecules such as ICAM-1 and endothelial-leucocyte adhesion molecule-1 (E-selectin) by cell ELISA. Pirfenidone significantly down-regulated the expression of ICAM-1 on cultured synovial fibroblasts in a dose-dependent manner. In contrast, expression of E-selectin was not affected. Furthermore, we examined whether pirfenidone affects the cellular binding between cultured lymphocytes and IL-1alpha-stimulated synovial fibroblasts by in vitro binding assay and found their mutual binding was significantly suppressed in a dose-dependent manner by pirfenidone. It is speculated that down-regulation of ICAM-1 might be one of the novel mechanisms of action of pirfenidone. These data indicate a novel mechanism of action for pirfenidone to reduce the activation of synovial fibroblasts.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed1998

Intraoperative versus postoperative suture adjustment after penetrating keratoplasty.

PURPOSE: To study the effects of running suture adjustment for reduction of astigmatism after penetrating keratoplasty. Suture adjustments performed during surgery and during the early postoperative and late postoperative periods were retrospectively compared. METHODS: We studied 53 patients who received running suture adjustment after penetrating keratoplasty, either intraoperatively (ISA group, n = 18), early (< 2 weeks) postoperatively (EPSA group, n = 19), or late (> 1 month) postoperatively (LPSA group, n = 16). Refractive and topographic astigmatism and corneal topography were examined at 1, 3, and 6 months after surgery. RESULTS: Overall mean refractive astigmatism and topographic astigmatism at 6 months were 2.55 +/- 1.61 D and 3.12 +/- 1.89 D, respectively (mean +/- SD). The mean refractive astigmatism and topographic astigmatism were 1.88 +/- 1.04 D and 2.35 +/- 1.35 D in the ISA group, 2.32 +/- 1.17 D and 2.70 +/- 1.21 D in the EPSA group, and 3.01 +/- 1.62 D and 4.62 +/- 2.51 D in the LPSA group, respectively (mean +/- SD). The LPSA group demonstrated significantly increased topographic astigmatism compared to the ISA group (p = 0.0048) and the EPSA group (p = 0.015). Although 31.6 and 25.0% of the EPSA and LPSA groups, respectively, did not require postoperative suture adjustments, more eyes (10/18 eyes, 55.6%) in the ISA group did not require the procedure. CONCLUSIONS: Early postoperative suture adjustment was more effective than late postoperative adjustment. Intraoperative suture adjustment may further reduce final astigmatism and the necessity for postoperative suture manipulation.

Adult↗
PubMed1998

Transplantation of amniotic membrane and limbal autograft for patients with recurrent pterygium associated with symblepharon.

AIM: Treatment of recurrent pterygium associated with symblepharon requires both suppression of fibrosis and reconstruction of limbal barrier. To achieve this, human amniotic membrane was transplanted and limbal autografts performed. METHODS: Four patients with severe symblepharon resulting from multiple surgeries for pterygium were treated. Human amniotic membrane was obtained at caesarean section and preserved until surgery. After excision of the fibrous tissues, the amniotic membrane was placed on the sclera, and a limbal autograft transplantation was performed using limbal tissues taken from the affected eye. RESULTS: Recurrence of symblepharon was not observed in any of the patients and significant suppression of the subconjunctival fibrosis was achieved. Ocular movement improved in all cases. Complete remission of pterygium regrowth occurred in three cases, and a slight (about 1 mm) recurrence occurred in one case. The limbal donor site showed the presence of mild depressions without the formation of pseudopterygium. CONCLUSION: Transplantation of human amniotic membrane with a limbal autograft appears to be a promising surgical treatment for reconstructing the ocular surface in patients with recurrent pterygium associated with symblepharon.

Aged↗
PubMed1998

Lecithin-bound superoxide dismutase in the prevention of neutrophil-induced damage of corneal tissue.

PURPOSE: To evaluate the effects of a lipophilic analog of superoxide dismutase (SOD) in the prevention of polymorphonuclear leukocyte (PMN)-induced damage to corneal epithelial cells in vitro and in bacterial corneal ulcers in vivo. METHODS: Immortalized human corneal epithelial cells (T-HCEC) were cocultured with human PMNs activated with N-formyl-methionyl-leucyl-phenylalanine for 18 hours, after which lactate dehydrogenase (LDH) activity of the supernatant was measured as a marker of cellular damage. The inhibitory effects of lecithin-bound SOD (PC-SOD) and unmodified SOD, as well as PMNs pretreated with anti-CD 18 monoclonal antibody, were compared with untreated control. The retention of each drug on the ocular surface of healthy volunteers was measured by flow cytometry using brush cytology samples. The protective effects of a 0.1% solution of PC-SOD on Pseudomonas aeruginosa corneal infection in guinea pigs were assessed by inflammatory grading scores and histology. RESULTS: Both PC-SOD and SOD effectively suppressed PMN-induced LDH release in T-HCEC in a dose-dependent manner. LDH release was also attenuated when PMNs were pretreated with anti-CD 18 antibodies, suggesting that adhesion molecules were involved in the process. Brush cytology of conjunctival samples showed that PC-SOD was retained longer on the ocular surface compared with unmodified SOD. PC-SOD significantly prevented excessive tissue damage by infiltrating PMNs in P. aeruginosa corneal infection, whereas in control eyes, perforation of the cornea occurred by 6 days. CONCLUSIONS: PC-SOD was effective in attenuating PMN-related tissue damage to corneal tissue both in vitro and in P. aeruginosa infection in guinea pigs.

Animals↗