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Biomedical subjects

I Ota

Publications and source records attributed to I Ota.

At least 37 records · Page 2Linked to original sources
PubMed1998

Liquefied aftercataract: a complication of continuous curvilinear capsulorhexis and intraocular lens implantation in the lens capsule.

PURPOSE: To describe a new type of aftercataract that contains a liquefied, milky white substance between the lens optic and the posterior lens capsule. METHOD: We reviewed the medical records of 41 patients identified as having this type of aftercataract. RESULTS: All 41 eyes (41 patients) underwent uneventful phacoemulsification after continuous curvilinear capsulorhexis and implantation of a posterior chamber intraocular lens made from polymethylmethacrylate. Two months to 6 years after surgery (average+/-SD, 3.8+/-1.7 years), fibrosis was noted evenly along the entire circumference and between the anterior surface of the intraocular lens optic and the edge of the capsular opening created by continuous curvilinear capsulorhexis. This led to formation of a closed chamber between the intraocular lens and the posterior lens capsule, which then accumulated a liquefied, milky white substance. Twenty-three of the 41 eyes showed liquefied aftercataract in conjunction with other types of aftercataract: in 12 eyes with fibrosis, in 11 eyes with Elschnig pearls, and in one eye with a Soemmering ring. None of the eyes had any signs of inflammation; six of the 41 eyes had reduced visual acuity caused exclusively by the liquefied aftercataract. Before cataract surgery, 14 eyes were diagnosed with diabetic retinopathy, four with glaucoma, and two with uveitis. CONCLUSION: We report a new type of aftercataract characterized by a liquefied, milky white substance that accumulates between the lens optic and the posterior lens capsule when the anterior capsular opening, originally created by continuous curvilinear capsulorhexis, becomes occluded with the lens optic.

Adult↗
PubMed1998

New classification of capsular block syndrome.

PURPOSE: To propose a new classification of capsular block syndrome (CBS) to improve understanding of the etiology and provide effective treatment. SETTING: Shohzankai Medical Foundation, Miyake Eye Hospital, Nagoya, and Japanese Red Cross Society, Wakayama Medical Center, Wakayama, Japan. METHODS: Three groups of eyes with CBS were reviewed: eyes originally reported and diagnosed as having CBS; eyes experiencing CBS after hydrodissection and luxation of the lens nucleus; and eyes with CBS accompanying liquefied aftercataract or capsulorhexis-related lacteocrumenasia. RESULTS: In all 3 groups, the CBS occurred in eyes with a continuous curvilinear capsulorhexis (CCC). It was characterized by accumulation of a liquefied substance within a closed chamber inside the capsular bag, formed because the lens nucleus or the posterior chamber intraocular lens (IOL) optic occluded the anterior capsular opening created by the CCC. Depending on the time of onset, CBS can be classified as intraoperative (CBS seen at the time of lens luxation following hydrodissection), early postoperative (original CBS), and late postoperative (CBS with liquefied aftercataract or lacteocrumenasia). The etiology of the accumulated substance and the method of treatment are different in each type. CONCLUSION: Capsular block syndrome is a complication of cataract/IOL surgery that can occur during and after surgery. Correctly identifying the type of CBS is crucial to understanding the nature and effective treatment of this disorder.

Capsulorhexis↗
PubMed1997

Two protein-tyrosine phosphatases inactivate the osmotic stress response pathway in yeast by targeting the mitogen-activated protein kinase, Hog1.

Protein phosphatases inactivate mitogen-activated protein kinase (MAPK) signaling pathways by dephosphorylating components of the MAPK cascade. Two genes encoding protein-tyrosine phosphatases, PTP2, and a new phosphatase, PTP3, have been isolated in a genetic selection for negative regulators of an osmotic stress response pathway called HOG, for high osmolarity glycerol, in budding yeast. PTP2 and PTP3 were isolated as multicopy suppressors of a severe growth defect due to hyperactivation of the HOG pathway. Phosphatase activity is required for suppression since mutation of the catalytic Cys residue in Ptp2 and Ptp3, destroys suppressor function and biochemical activity. The substrate of these phosphatases is likely to be the MAPK, Hog1. Catalytically inactive Ptp2 and Ptp3 coprecipitate with Hog1 from yeast extracts. In addition, strains lacking PTP2 and PTP3 do not dephosphorylate Hog1-phosphotyrosine as well as wild type. The latter suggests that PTP2 and PTP3 play a role in adaptation. Consistent with this role, osmotic stress induces expression of PTP2 and PTP3 transcripts in a Hog1-dependent manner. Thus Ptp2 and Ptp3 likely act in a negative feedback loop to inactivate Hog1.

Amino Acid Sequence↗
PubMed1997

[Adhesion molecules and cancer metastasis].

Integrins are the major family of cell surface receptors that mediate adhesion to the extracellular matrix and sometimes cell-cell adhesive interactions. These integrin-mediated adhesive interactions are involved in the regulation of many cellular functions, including embryonic development, tumor cell growth and metastasis, programmed cell death, hemostasis, inflammation, immune reaction, bone reabsorption, etc. Integrins are composed of alpha and beta transmembrane subunits selected from among 16 alpha and 8 beta subunits that heterodimerize to produce more than 20 different receptors which bind specific ligands. Integrins link to intracellular cytoskeletal complexes and bundles of actin filaments. There have been many reports about intracellular signaling pathways activated by integrin-ligand interactions. Integrin may play an important role in tumor metastasis through its interaction with extracellular matrix and endothelial cell. We have examined the role of each integrin in tumor metastasis by using transfection of integrin cDNA into various cells. Transfection of integrin alpha 2 subunit into RD cells, human rhabdomyosarcoma cells which do not express integrin alpha 2 beta 1, potentiated the frequency of metastases in various organs; lung, bone, adrenal gland, lymphnode. alpha 4-transfectant of Chinese hamster ovary (CHO) cells, which do not have alpha 4 beta 1 on the cell surface, metastasized to bone through its interaction with VCAM-1 in the bone marrow stroma cells. On the other hand, alpha 5-transfectant of CHO cells was much less tumorigenic than parent CHO cells. These data suggest integrin influence tumor metastasis sometimes favorably and sometimes unfavorably according to the activity and the balance of various integrins.

Animals↗
PubMed1996

Dislocation of the lens nucleus into the vitreous cavity after standard hydrodissection.

PURPOSE: Having encountered dislocation of the lens nucleus into the vitreous cavity immediately after continuous tear capsulorhexis and hydrodissection of the nucleus, we examined common features of eyes with this complication. METHODS: We reviewed consecutive cases of cataract extraction. RESULTS: The complication occurred in four of 10,126 eyes. All four eyes were in elderly patients and except for the patient whose contralateral eye had pseudoexfoliation syndrome, all eyes had an increased axial length. CONCLUSION: In elderly patients with eyes that have a long axial length or pseudoexfoliation, we recommend performing hydrodissection with extreme care and only when necessary.

Aged↗
PubMed1996

Correlation between intraocular lens hydrophilicity and anterior capsule opacification and aqueous flare.

PURPOSE: To study the correlation between a basic parameter of intraocular lens biocompatibility, hydrophilicity, and two clinical parameters, postoperative inflammation and anterior capsule opacification. SETTING: Miyake Eye Hospital, Nagoya, Japan. METHODS: Three combinations of IOLs that were identical in shape but had distinct contact angles of water were used in this prospective double-masked study: (1) experimental comparison of collagen type IV and poly(methyl methacrylate) (PMMA) IOLs in rabbit eyes; (2) clinical comparison of heparin-surface-modified and PMMA IOLs; (3) clinical comparison of three foldable IOLs, silicone, acrylic, and memory. One of the two IOLs being compared in each situation was randomly assigned to both eyes of each animal or patient. At 1 and 3 months postoperatively, the degree of anterior capsule opacification and the amount of flare in the anterior chamber were determined. RESULTS: In all three comparative situations, greater postoperative inflammation and more rapid anterior capsule opacification was seen in the eyes with hydrophobic IOLs. CONCLUSION: There was a correlation between the hydrophilicity of an IOL and the severity of postoperative inflammation and the speed of anterior capsule opacification.

Acrylic Resins↗
PubMed1993

Focal macular electroretinogram in X-linked congenital retinoschisis.

PURPOSE: To study macular function of X-linked congenital retinoschisis (CRS) by focal macular electroretinogram (MERG). METHODS: MERGs were recorded with 5 degrees, 10 degrees, and 15 degrees spots in 20 patients with CRS. Seventeen patients showed foveal schisis with little or no change in foveal fluorescein angiography (Group 1), and three patients showed advanced macular changes with nonspecific macular degeneration (Group 2). RESULTS: In Group 1, a-wave amplitudes were within the normal range, but b-waves and oscillatory potentials (OPs) had mean amplitudes significantly below those for normal control subjects. The mean b- to a-wave ratios, significantly lower than in normal eyes, decreased significantly with decreasing spot size. The implicit times of a-waves, b-waves, and OPs were significantly delayed. In Group 2, MERGs were nearly nondectable. CONCLUSIONS: The macular pathology of CSR exists mainly in the middle and inner retinal layers, disturbing the fovea more than the perifovea, whereas degeneration of photoreceptors progresses in more advanced stage.

Adolescent↗
PubMed1991

[Detection of deletions in platelet mitochondrial DNA in Kearns-Sayre syndrome using polymerase chain reaction].

Kearns-Sayre syndrome has been genetically diagnosed by detecting deleted mitochondrial DNA in muscle biopsy specimen using the Southern blot method. However, deleted mitochondrial DNA cannot be detected in the blood by this method. With the limited availability of muscle biopsy specimens in mind, we attempted to establish a noninvasive genetic diagnostic method for this syndrome. The polymerase chain reaction (PCR) was employed for detecting mitochondrial DNA deletions in platelets at levels below the sensitivity of Southern blotting. We selected several pairs of oligonucleotide primers, considering the regions of predilection for deletion in this syndrome, and identified mitochondrial DNA deletions in platelets in three of four patients. The size and the locations of the deletions were determined by the nesting primer PCR method, in which the primary PCR products derived from deleted mitochondrial DNAs were subjected for reamplification using a series of nesting primers. By this method, it was possible to determine whether the products retained a complementary site for each primer. Patient 1 had an 8.3-kb deletion starting within the CO1 gene and ending within the Cyt b gene. Patient 2 had a 7.2-kb deletion starting within the CO1 gene and ending within the ND5 gene. Patient 3 had a 4.7-kb deletion starting within the ATPase6 or the CO3 gene and ending within the ND5 gene. Deletions were detected neither in Patient 4 nor in three mothers of four patients. These results indicate that the present method is useful for noninvasive genetic diagnosis of Kearns-Sayre syndrome.

Adolescent↗
PubMed1989

Asymmetry of focal ERG in human macular region.

Electroretinograms (ERGs) were elicited by hemicircular (half-disc) stimuli to the upper, lower, temporal and nasal maculas of 26 normal subjects, and the amplitudes and implicit times of the ERGs from opposing macular regions were compared. The amplitudes of a-wave, b-wave and oscillatory potentials (OPs) were significantly larger in the upper macular region than in the lower macular region (P less than 0.05). The amplitudes of a- and b-waves did not differ significantly between temporal and nasal macular regions, but OPs showed enormous asymmetry, with significantly larger amplitudes in the temporal retina than in the nasal retina (P less than 0.001). The implicit times of a-waves, b-waves and OPs did not differ significantly between upper and lower retina, or between temporal and nasal retina. These findings aided analysis of the ERG of a patient with a retinal defect.

Adolescent↗
PubMed1989

[Studies of ocular fundus and visual functions in Kearns-Sayre syndrome--with special reference to the new stage classification].

This paper describes the fundus appearance, visual function and electrophysiological findings in five cases of Kearns-Sayre syndrome. In three of them, retinopathy was not seen before the onset of this syndrome. The characteristic "salt and pepper retinopathy" progressed to peripapillary loss of the RPE and choriocapillaris over a period of some years. The ERG, normal in the beginning, became extinct in these cases. They were also at first subnormal for the scotopic as well as for the photopic activity. We distinguished five stages of ocular manifestations in Kearns-Sayre syndrome. Stage 0: The fundus appearance and the visual function are normal. Stage I: "Salt and pepper retinopathy" occurs in the entire retina but the visual function and the ERG are still normal. Stage II: Abnormal visual function and ERG occur with retinopathy. Stage III: A chorioretinal atrophy progresses around the disc and nasal retina and the ERG becomes extinct. Stage IV: The retinopathy demonstrates the appearance of choroidal sclerosis.

Adolescent↗
PubMed1988

Local macular electroretinographic responses in idiopathic central serous chorioretinopathy.

Using focal stimuli to human macular regions, we recorded electroretinograms in 24 patients with central serous chorioretinopathy of recent onset (mean visual acuity, 20/20). The stimulus spot was 10 degrees in diameter. Intact fellow eyes served as controls. The local macular electroretinograms of the affected eyes were significantly reduced and the implicit time in each component was significantly prolonged. The mean (+/- S.D.) amplitudes, expressed as percentages of mean amplitudes recorded in fellow eyes, were 64.6% +/- 22.7% (a-wave), 49.6% +/- 21.0% (b-wave), and 15.0% +/- 21.6% (oscillatory potentials). Two to five months after the macular detachment resolved, recordings in 18 patients showed remarkable recovery of a- and b-waves and shortened implicit times. However, the oscillatory potentials showed significantly small recovery in amplitude. Since oscillatory potentials and b-waves were significantly more deteriorated than a-waves in the presence of macular detachment, and oscillatory potentials showed selective delay of recovery in the convalescent stage, central serous chorioretinopathy may involve functional disturbances in the inner retinal layer as well as the photoreceptors.

Adult↗
PubMed1988

Oscillatory potentials in electroretinograms of the human macular region.

Using focal stimuli, we successfully recorded oscillatory potentials (OPs) in electroretinograms of the macular regions of 72 normal volunteers. The OPs consisted of three to four wavelets with a mean peak interval of approximately 6.5 msec, consistent with that recorded with conventional full-field stimuli over the entire retina. The changes of amplitude in response to the spot sizes and ring stimuli suggested that the distribution of OPs is different from that in a- and b-waves in human macular region.

Action Potentials↗
PubMed1987

Characteristic ERG-flicker anomaly in incomplete congenital stationary night blindness.

Ten patients with the incomplete type of congenital stationary night blindness (CSNB) were examined with a 30 Hz flicker electroretinogram (ERG). After 30 min of dark adaptation, 30 Hz flicker ERG was recorded continuously for 12-15 min under white background illumination. All patients showed an exaggerated increase of amplitude and a universal characteristic change of wave shape as the light adaptation progressed. Thirty normal subjects also showed increased amplitude during light adaptation, but the increase in amplitude was significantly less than in incomplete-type CSNB, and there was little change in wave shape. The same procedure was applied to patients with complete-type CSNB, retinitis pigmentosa, congenital retinoschisis, cone dystrophy, and Oguchi's disease; neither the exaggerated increase of amplitude nor the wave change was seen. Our results indicate that incomplete-type CSNB is a newly identified cone-rod dysfunction syndrome with a special functional property.

Electroretinography↗
PubMed1986

The pattern electroretinogram in patients with optic nerve disease.

We analyzed the electroretinogram elicited by pattern stimuli (PERG) in 29 patients with unilateral optic nerve disease. The normal fellow eyes served as a control. When the normal fellow eye was covered and the patient was asked to watch the center of the pattern stimuli with the affected eye, the poor fixation often caused irregular eye movements which resulted in a poor reproducibility of the response. In such instance we opened the normal fellow eye for fixation, which helped to stabilize the affected eye being examined even when visual acuity was extremely poor. The cross-talk phenomenon of the ERG and the reflection of the VER from the normal fellow eye were proved negligible in this recording condition. We analyzed PERGs in comparison with the visual acuity and the degree of optic atrophy. Unlike the results of many previous authors, little correlation was observed between PERG and these two factors. Most patient showed normal or only slightly abnormal PERG, even when the visual acuity was extremely poor and the optic disc was completely atrophic. Our results suggest that, at least with our method, PERG has extremely limited value in detection of optic nerve disease.

Adult↗
PubMed1986

[Severity and extent of coronary artery disease and their relationship to left ventricular functional reserve in the chronic disease state].

Our previous observations showed that left ventricular wall motion abnormality (asynergy) induced by stress was observed in the phase response of radionuclide technique, and the severity and extent of coronary artery disease (CAD) assessed by the Pujadas score (PS) correlated well with the maximal phase delay response (delta MPD) but not with the ejection fraction response (delta EF) in patients with CAD without old myocardial infarction (MI). This study evaluated the usefulness of EF, MPD and the first-third filling fraction (FF, divided by the volume accrued throughout diastole) at rest and during stress, using ergometer and first-pass radionuclide angiocardiography (RNA), to determine the severity of CAD, and to evaluate any abnormalities in the systolic and diastolic coupling in left ventricular function during stress. Seventy-four patients with significant CAD, including 41 with previous transmural MI (MI group) and 33 without MI (angina group) were the subjects of this study. EF at rest and during stress inversely correlated, and MPD on stress linearly correlated with PS in angina group with PS greater than 10, while no such correlations were found in MI group. A normal EF response (delta EF greater than or equal to 5%) was accompanied by a greater-than-normal response in FF (delta FF) in both groups. A lower EF response was accompanied by a smaller delta FF in angina group, but by a larger delta FF in MI group. The difference was statistically significant (p less than 0.03), without significant differences by age, PS, peak heart rate, systolic blood pressure, and ischemia on ECG during stress. Resting EF and FF by the RNA method correlated with those by left ventriculography (LVG), respectively. It was suggested that RNA is an accurate method for determining EF and FF, while phase analysis may provide some additional information different from that provided by LVG. We concluded that EF and MPD during stress are as useful as delta MPD with the exception of a few cases in predicting the severity of CAD, and that scar tissue within the ventricular wall in MI may play an important role in determining the ventricular diastolic mechanical property during stress.

Angina Pectoris↗