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Biomedical subjects

N Yokoi

Publications and source records attributed to N Yokoi.

At least 37 records · Page 2Linked to original sources
PubMed2000

The height and radius of the tear meniscus and methods for examining these parameters.

PURPOSE: To investigate the relationship between the radius of tear meniscus curvature (TMR) and tear meniscus height (TMH). METHODS: Twenty-nine eyes of dry-eye patients (all left eyes; two males, 27 females, aged 26 to 85 years [mean +/- SD; 60 +/- 14.4]) were enrolled in the study. TMR was measured at the tear meniscus of the central lower lid with a newly developed videomeniscometer. At the same region of the eye, TMHs were measured without fluorescein (TMH-M) and after 5 minutes with fluorescein (TMH-MF), using a slit lamp equipped with a micrometer. TMHs were also measured on cross-sectional photographs of the fluorescein-stained meniscus (TMH-P). RESULTS: The values of TMR, TMH-M, TMH-MF, and TMH-P (mean +/- SD, mm) were 0.22 +/- 0.09, 0.19 +/- 0.09, 0.21 +/- 0.14, and 0.24 +/- 0.09, respectively. There was significant correlation between TMR and TMH-M, TMH-MF, and TMH-P values (TMR versus TMH-M: r = 0.596, p = 0.0005; TMR versus TMH-MF: r = 0.587, p = 0.0006; TMR versus TMH-P: r = 0.605, p = 0.0003). CONCLUSION: There is a significant correlation between TMR and TMH. Videomeniscometry has some merits over conventional methods for obtaining tear meniscus parameters.

Adult↗
PubMed2000

Observation of corneal epithelial disturbance through soft contact lens using fluorescein dextran.

PURPOSE: To confirm the usefulness of fluorescein dextran as a vital dye for observing corneal epithelial disturbance through a medical-use soft contact lens. METHODS: Ten percent fluorescein isothiocyanate-dextran (FITC-dextran) was used as the staining dye. Patients with corneal epithelial disturbance who were wearing therapeutic soft contact lenses were observed using FITC-dextran. RESULTS: Through the soft contact lens, FITC-dextran enabled corneal disturbance observation similar to that seen with sodium fluorescein. In a case of corneal perforation, as well, positive Seidel's test was confirmed through the soft contact lens using this technique. CONCLUSION: FITC-dextran is considered a useful dye for examining the corneal epithelial condition without contact lens removal.

Adult↗
PubMed2000

[Comparison of primary and secondary Sjögren's syndrome].

PURPOSE: We studied the difference in severity between primary and secondary Sjögren's syndrome (SS). SUBJECTS AND METHODS: Two groups of patients (all females, mean age: 58 years), 31 with primary SS and 18 with secondary SS were studied. We performed the following dry eye tests: fluorescein score and Rose Bengal staining, grading of tear lipid layer interference patterns, measurement of fluorescein break up time, cotton thread test, and Schirmer-I test. Auto antibodies were also investigated. RESULTS: There was no significant difference between primary and secondary SS with respect to any dry eye tests or auto antibodies. In primary SS, however, the presence of anti SS-A antibody was significantly correlated with Rose Bengal scores (p = 0.044). CONCLUSION: The severity of SS is independent of the primary or secondary type. In primary SS, the presence of anti SS-A antibody may be correlated with the severity.

Adult↗
PubMed2000

[Investigation of corneal autofluorescence in diabetic patients].

PURPOSE: The investigation of corneal autofluorescence in diabetic patients. OBJECTS AND METHODS: Corneal autofluorescence was investigated with a newly-developed fluorophotometer (wave length: excitation, 290-390 nm; emission, 430-630 nm) having, fluorescence characteristics involving those of reduced pyridine nucleotides (PN) and advanced glycation endoproduct (AGE) except pentosidine and pyrraline. Twenty-eight patients with non-insulin-dependent diabetes mellitus and sixty-seven healthy volunteers were studied. RESULTS: The corneal autofluorescence was 1.65 times higher than that of controls (p < 0.0001). In non-insulin-dependent diabetes mellitus, the corneal autofluorescence was not correlated significantly with various diabetic parameters in blood (r < 0.4). In controls, the corneal autofluorescence was correlated significantly with age (r = 0.438). CONCLUSION: The corneal autofluorescence has some relation with PN and AGE accumulation in the cornea.

Adolescent↗
PubMed2000

[Sialic acid in normal human tears].

PURPOSE: We measured the concentration of sialic acid, the terminal component of mucin, in normal human tears. SUBJECTS AND METHODS: Tear samples were collected from 31 healthy volunteers(50.7 years old on average) using micropipett after instillation of saline. We investigated the correlation of concentration between glycoprotein and sialic acid, the difference between these in the right eye and left eye, and the reproducibility of the sampling procedure. RESULTS: There was significant correlation of concentration between glycoprotein and sialic acid(right eye: r = 0.989, p < 0.0001; left eye: r = 0.988, p < 0.0001). There was no significant difference between these in the right and left eye. Also, the reproducibility was considered acceptable in three measurements of sialic acid with the present procedure. The concentration of sialic acid in normal diluted tears was 37.1 micrograms/ml on average. CONCLUSION: Our data indicates that concentration of sialic acid reflects that of glycoprotein and this method of measurement is applicable to the analysis of disorders with mucin deficiency.

Female↗
PubMed2000

Tear meniscus changes during cotton thread and Schirmer testing.

PURPOSE: To elucidate the effect of the cotton thread test (CT-T) and Schirmer test (S-T) on the tear reservoir by evaluating the radius of tear meniscus curvature. METHODS: The radii (R) of the central lower tear menisci were measured by a newly developed video meniscometer in 11 eyes of 11 normal volunteers (6 men, 5 women; mean age, 27.7 +/- 3.6 years [SD]) and 9 eyes of 9 patients with tear deficiency and severe dry eye in whom the puncta had been therapeutically occluded (9 women; mean age, 50.6 +/- 10.4 years). In this dry eye group, the absence of reflex tearing, coupled with the absence of lacrimal drainage due to punctal occlusion allowed more precise observation of the removal of tears from the meniscus. A 1-minute CT-T was performed, followed after an interval of 10 minutes by a 1-minute S-T. Tear meniscus curvature was documented before (R:(0)) and during the tests at 30 seconds (R(30)) and 60 seconds (R:(60)). RESULTS: In the normal group, respective R values (CT-T; S-T; mean +/- SD mm) were R(0) (0.26 +/- 0.11; 0.26 +/- 0. 07), R(30) (0.27 +/- 0.16; 0.20 +/- 0.13), and R(60) (0.29 +/- 0.15; 0.23 +/- 0.21); and in the dry eye group, respective R: values (CT-T; S-T) were R(0) (0.59 +/- 0.23; 0.51 +/- 0.19), R(30) (0.52 +/- 0.25; 0.22 +/- 0.09), and R(60) (0.51 +/- 0.19; 0.21 +/- 0.08). It was demonstrated in the dry eye group that R was diminished more by the S-T than by the CT-T in the time course of the measurement (P = 0.01). In the dry eye group alteration of R occurred within the first 30 seconds, and in this group significant correlation was found between R(0) and the S-T result (r = 0.67; P = 0.05), and between R(60)- R(0) and the S-T result (r = -0.81; P = 0.01). Also, there was a significant correlation between R(60)- R(0) and the S-T result in the normal group (r = 0.71; P = 0.02). There were no significant correlations between R(0) or R(60)- R(0) and the CT-T results in either group. CONCLUSIONS: These studies afford some insight into the dynamics of the Schirmer test, suggesting that wetting is influenced by the negative hydrostatic pressure within the tear meniscus. With the protocol used, no conclusion could be drawn about the relation between meniscus radius and wetting of the cotton thread.

Adult↗
PubMed2000

[Corneal epithelial disturbance during topical use of latanoprost].

PURPOSE: To report two cases with corneal epithelial disturbance during topical use of the new prostaglandin F 2 alpha derivative latanoprost and a beta-blocker. CASES: Both case 1 (82-year-old male) and case 2 (50-year-old female) were treated with topical antiglaucoma drugs for ocular hypertension. FINDINGS: One month (case 1) and 10 days (case 2) after treatment with topical beta-blocker and latanoprost, corneal epithelial disturbance occurred. The corneal epithelial disturbance improved over several weeks with the preservative-free artificial tears after discontinuation of latanoprost and the beta-blocker. CONCLUSION: Careful observation is necessary during the course of treatment with latanoprost and a beta-blocker.

Administration, Topical↗
PubMed1999

Angiopoietin-3, a novel member of the angiopoietin family.

A cDNA clone encoding angiopoietin-3 protein (Ang3), a novel member of the angiopoietin family, was identified. Ang3 cDNA was cloned from a human aorta cDNA library. Ang3 is a 503 amino acid protein having 45.1% and 44.7% identity with human angiopoietin-1 and human angiopoietin-2, respectively. Ang3 mRNA is expressed in lung and cultured human umbilical vein endothelial cells (HUVECs). Ang3 mRNA expression in HUVECs was slightly decreased by vascular endothelial cell growth factor treatment, suggesting that the regulation of Ang3 mRNA expression is different from that of Ang2.

Amino Acid Sequence↗
PubMed1999

Assessment of meibomian gland function in dry eye using meibometry.

OBJECTIVE: To study meibomian gland function in dry eyes using meibometry. METHODS: Forty-two patients with clinically diagnosed dry eye that was reclassified as meibomian gland dysfunction (MGD [n = 12]), aqueous-tear deficiency (AD [n = 10]), MGD combined with AD (n = 2), "incomplete" dry eye (n = 12), and non-dry eye (6 eyes) were compared with 41 healthy control subjects. The following 2 techniques of meibometry were applied: direct meibometry (DM) measuring lipid imprints using the Meibometer, and integrated meibometry (IM) using image-scanning and computer densitometry. Tear film lipid layer thickness was assessed using interference microscopy. RESULTS: Imprints were homogeneous for all subjects except those with MGD. Mean+/-SE readings on results of DM were 127.24+/-24.4 for MGD, 306.4+/-9.2 for AD, 248.6+/-13.2 for incomplete dry eye, and 268.5+/-6.3 for controls, showing lower values in the MGD group relative to all others (P<.001). Results of IM gave similar results (P<.001, P =.01, and P<.001, respectively). Lipid layers appeared lower for the MGD group than others. CONCLUSIONS: Compared with controls, lid lipid levels are reduced in patients with MGD, and increased in women with AD. Lipid layer thickness is increased in women with AD compared with patients with MGD. Both meibometric techniques may be useful for evaluating MGD. Although DM requires special equipment (the Meibometer), it provides a record of immediate diagnostic value. Although IM is less effective than DM, it offers visual documentation of the lipid imprint, which may itself be of diagnostic value, and uses equipment available in many laboratories.

Aged↗
PubMed1999

Classification of polycystic ovary syndrome into three types according to response to human corticotropin-releasing hormone.

OBJECTIVE: To evaluate disturbances of the hypothalamic-pituitary-adrenal axis in women with polycystic ovary syndrome (PCOS). DESIGN: Retrospective cohort study. SETTING: Yokohama City University, Yokohama, Japan. PATIENT(S): Sixty women with PCOS and 19 women with normal menstruation. INTERVENTION(S): Administration of human corticotropin-releasing hormone (hCRH), dexamethasone suppression testing, and stimulation of ovulation with clomiphene citrate. MAIN OUTCOME MEASURE(S): Plasma cortisol and ACTH levels, plasma androstenedione and DHEAS levels, and ovulation rates. RESULT(S): In women with PCOS, plasma ACTH and cortisol levels were significantly higher and the plasma ACTH level after the administration of hCRH was higher than in controls. Based on the response to hCRH, patients with PCOS could be classified into three categories: those with a normal response to hCRH (group 1), those with an exaggerated response of ACTH to hCRH (group 2), and those with a high basal level of cortisol and a poor response to hCRH (group 3). In groups 2 and 3, DHEAS levels were significantly higher, suppression of androstenedione by dexamethasone was significantly greater, and ovulation rates with clomiphene citrate were significantly lower than in group 1. CONCLUSION(S): This classification provides insight into the underlying cause of PCOS and thus is useful in selecting appropriate treatment.

17-alpha-Hydroxyprogesterone↗
PubMed1999

Tear film instability induced by rigid contact lenses.

PURPOSE: To evaluate rigid contact lens-associated epithelial damage, the relationship between the tear film and the ocular surface epithelium was evaluated at the perilimbal area around rigid contact lenses (RCLs). METHODS: Twenty RCL [six polymethylmethacrylate (PMMA) and 14 rigid gas-permeable lens (RGPL)] wearers and 20 non-CL wearers were enrolled in this study. By using a newly developed tear interferometer, the noninvasive tear film break-up time (NIBUT) on the conjunctiva at the 3- and 9-o'clock portions was measured, and its stability evaluated. Fluorescein and sulforhodamine B staining was used to observe ocular-surface epithelial damage, and rose bengal staining was used to evaluate the mucin layer distribution. RESULTS: The conjunctival NIBUT at the 3- or 9-o'clock portions or both was abnormally shortened in 15 (75%) of 20 RCL-wearer eyes. Conjunctival epithelial staining at the 3- or 9-o'clock portion was seen in six (30%) of 20 eyes by using sulforhodamine B, and in four (20%) of 20 eyes by rose bengal; all of these eyes also demonstrated an abnormal tear film breakup. Corneal epithelial damage was seen in two (10%) of 20 RCL-wearer eyes at the 3- or 9-o'clock portions or both, and in both of these cases, conjunctival epithelial damage also was noted. Neither tear-film instability nor epithelial staining was seen in the normal controls. CONCLUSIONS: This study indicates that RCL-induced tear-film instability is associated with damage to the ocular-surface epithelium and mucin layer.

Adult↗
PubMed1999

Reflective meniscometry: a non-invasive method to measure tear meniscus curvature.

AIMS: To devise a method to measure tear meniscus curvature by a non-invasive specular technique. METHODS: A photographic system was devised. The system consisted of a camera and an illuminated target with a series of black and white stripes oriented parallel to the axis of the lower tear meniscus. The target was mounted on a flash gun close to the objective of a Brown macrocamera and calibrated using a graduated series of glass capillaries of known diameter, ground down to expose the inner wall. It was then applied to normal human eyes (n = 45) to measure the tear meniscus curvature. A video system was also assessed which provided qualitative online information about the tear meniscus. RESULTS: Using the photographic system, measured values for capillary radii were in excellent agreement with theoretical calculations (r2 = 0.996, p < 0.0001). The radii of curvature of lower tear menisci in normal human subjects (mean 0.365 (SD 0.153) mm, range 0.128-0.736; n = 45) were similar to those reported in the literature. Both systems demonstrated variations in meniscus shape. The video system provided stable images of human menisci over prolonged periods of time and promises to be useful for the analysis of dynamic changes in meniscus volume. CONCLUSIONS: Reflective meniscometry is a non-invasive technique providing quantitative information about tear meniscus shape and volume and of potential value in the study of ocular surface disease.

Calibration↗
PubMed1999

Detection of herpes simplex virus DNA in atypical epithelial keratitis using polymerase chain reaction.

AIM: To study herpes simplex virus (HSV) DNA in tears from patients with atypical epithelial keratitis of unknown aetiology. METHODS: Tear samples were collected from 17 affected eyes of 17 consecutive patients suffering from epithelial keratitis in whom HSV keratitis was suspected but whose diagnosis was difficult on the basis of clinical manifestations alone. Using reduced sensitivity polymerase chain reaction (PCR), tear samples were tested for HSV DNA. Tears from the unaffected eyes of the 17 patients were also examined, along with 38 tear samples from 19 normal volunteers. Southern blot analysis was performed to confirm that amplified DNA bands were specific for HSV. Clinical correlation with photographs of corneal lesions was also investigated. RESULTS: HSV DNA was detected in tears from the affected eyes of eight of the 17 patients with suspected HSV keratitis. Tears from the affected eyes of the other patients were PCR negative, as were tears from the unaffected eyes of all 17 patients, and from the 38 normal eyes. There was no correlation between PCR results and clinical manifestation of keratitis. CONCLUSIONS: Based on the sensitivity of the PCR system, eight of 17 suspected HSV keratitis patients were confirmed as suffering from HSV keratitis. HSV keratitis should therefore be considered as a possible diagnosis in atypical epithelial keratitis.

Adult↗
PubMed1999

Fluorophotometric assessment of rabbit corneal epithelial barrier function after rigid contact lens wear.

PURPOSE: The effect of overnight wear of graded rigid gas-permeable (RGP) contact lenses on the rabbit corneal epithelial barrier function was assessed by fluorophotometry. METHODS: RGP lenses with optimal fitting were worn by rabbits for 24 h. The values of oxygen transmissibility (Dk/L) of lenses used were 0, 10, 27, 43, 84, and 109 x 10(-9) (cm/s)(ml O2/ml mm Hg); lens thickness (0.15 mm) and diameter (14.0 mm) were standardized. Corneal epithelial barrier function was measured by a slit-lamp fluorophotometer. Corneal surface lesions by fluorescein staining were observed by a slit-lamp biomicroscope with the aid of fluorescein filter paper and were scored. Corneal epithelial structure was observed by scanning electron microscopy (SEM). RESULTS: After 24-h wear of RGP lenses, fluorescein uptake by the cornea increased, and this increase depended on the Dk/L value of lenses worn; mean +/- standard error, 1,601+/-454 (Dk/L 0), 347+/-226 (Dk/L 10), 144+/-42 (Dk/L 27), 100+/-25 (Dk/L 43), 56+/-18 (Dk/L 84), 51+/-15 (Dk/L 109), and 49+/-4 ng/ml (control). There was a significant correlation between the fluorophotometric value and the biomicroscopic scores of corneal lesions. SEM showed progressive desquamation of epithelial superficial and wing cells for lower-value Dk/L lens groups. CONCLUSION: This study demonstrated for the first time that overnight wear of Dk/L 84 and 109 lenses does not alter the barrier function of the rabbit corneal epithelium. In contrast, wear of a PMMA lens greatly alters the corneal epithelial barrier function. It is suggested that RGP lenses with a Dk/L >80 can provide safe overnight wear, based on the epithelial barrier function.

Animals↗