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Biomedical subjects

N Yokoi

Publications and source records attributed to N Yokoi.

At least 73 records · Page 4Linked to original sources
PubMed1996

Association of eosinophil granule major basic protein with atopic cataract.

PURPOSE: To investigate the mechanism of atopic cataract development, we examined a tissue-destroying major basic protein, derived from eosinophils, in the anterior capsule of cataractous lenses and the aqueous fluid of atopic dermatitis patients. METHODS: Major basic protein deposition in anterior capsule tissues was evaluated immunohistochemically using anti-major basic protein monoclonal antibody in three consecutive eyes from three atopic cataract patients and three consecutive eyes from three senile cataract patients. Also, major basic protein concentration in aqueous fluid obtained during cataract surgery was measured by radioimmunoassay in 12 consecutive eyes from 11 atopic cataract patients and 15 consecutive eyes from 15 senile cataract patients. RESULTS: Immunohistochemical investigation demonstrated lens epithelial major basic protein deposition in all three atopic cataracts but not in any of the senile cataracts. Major basic protein was detected in the aqueous fluid by radioimmunoassay in four of the 12 atopic cataract eyes and ranged in concentration from 11 to 70 ng/ml. No major basic protein was detected in the aqueous fluid of the 15 senile cataract eyes. CONCLUSION: Major basic protein in anterior capsule tissues and in the aqueous fluid of eyes with atopic cataract may be associated with the pathogenesis of atopic cataract.

Adolescent↗
PubMed1996

Epithelial barrier function of the filtering bleb conjunctiva and the cornea after trabeculectomy with mitomycin C.

PURPOSE: To evaluate epithelial barrier function of the filtering bleb conjunctiva and the cornea after trabeculectomy with adjunct, intraoperative mitomycin C, by using a newly developed slit-lamp fluorophotometer. SUBJECTS AND METHODS: Thirteen patients with normal-tension glaucoma with a cystic filtering bleb who had undergone unilateral trabeculectomy with mitomycin C only once at least 1 year previously were subjected to the study. Epithelial barrier function of the bleb conjunctiva and the cornea in the operated eye was evaluated using an Anterior Fluorometer FL-500 to measure the uptake of topically applied fluorescein. RESULTS: Fluorescein uptake (nanograms per milliliter, mean +/- standard error) by the bleb conjunctiva (1,857 +/- 380) was not significantly different from either the uptake by the superior bulbar conjunctiva in the operated eyes, located approximately 90 degrees C away from the filtering bleb (1,974 +/- 258), or the uptake by the conjunctiva in the intact eyes, located symmetrically against the bleb (1,913 +/- 248). The corneal uptake in the operated eye (56.1 +/- 10.2) was not significantly different from that in the intact eye (53.5 +/- 8.3). CONCLUSIONS: Epithelial barrier function of the cystic filtering bleb conjunctiva and the cornea long after trabeculectomy with mitomycin C was demonstrated to be almost identical to that of the control.

Aged↗
PubMed1995

Transforming growth factor-beta 1, -beta 2 and -beta 3 mRNA expression in human cornea.

The expression of TGF-beta 1, TGF-beta 2 and TGF-beta 3 precursors mRNA transcripts in in vivo human corneal cells were studied. Complementary DNA (cDNA) was generated from poly A+RNA extracted from in vivo human corneal epithelial cells, stromal keratocytes and endothelial cells. With the cDNAs as template, polymerase chain reaction (PCR) was carried out using specific primers of TGF-beta 1, TGF-beta 2 and TGF-beta 3 precursors, synthesized by choosing specific nucleotide sequences in the latency-associated peptide region of each precursor. Southern blot analysis of the PCR products was carried out. In corneal epithelial cells, TGF-beta 2 mRNA transcript was strongly expressed; TGF-beta 1 and -beta 3 mRNA transcripts were also expressed; stromal keratocyte samples expressed TGF-beta 1 and -beta 2 mRNA transcripts but not TGF-beta 3 mRNA transcript. Endothelial cells expressed all three transcripts. The present study, together with the authors' previous immunohistochemical study demonstrates that both protein and mRNA of TGF-beta 2-LAP are present in human corneal epithelium, indicating that TGF-beta 2 may play a crucial role in corneal epithelial cell layers.

Aged↗
PubMed1995

[Quantitative evaluation of corneal epithelial barrier function in corneal epithelial edema].

Corneal epithelial barrier function in patients with corneal epithelial edema was evaluated by fluorophotometry. Fluorescein uptake through the intact corneal epithelium was 28.1 +/- 2.7 ng/ml (n = 35, mean +/- SE (standard error), calculated from the standard line) at 30 minutes after instillation of 3 microliters of 0.5% sodium fluorescein (20 minutes after eye washing with 20 ml of BSS PLUS). Fluorescein uptake by the cornea in 7 patients with corneal epithelial edema and 6 patients with corneal stromal edema without epithelial edema were 2,489.7 +/- 1,045.6 ng/ml and 99.3 +/- 25.0 ng/ml, respectively, showing a significant increase when compared to normal corneal epithelium (p < 0.0005). Moreover, in patients with corneal epithelial edema, the corneal epithelial barrier function showed significant decrease in comparison with those having corneal stromal edema without epithelial edema (p < 0.05). These results demonstrate a significant decrease in the corneal epithelial barrier function in the epithelial edema.

Cornea↗
PubMed1995

[Corneal autofluorescence in patients with diabetic retinopathy].

Corneal autofluorescence was investigated by fluorophotometry in patients with non-insulin-dependent diabetes mellitus and healthy volunteers, and evaluated as to its correlation with diabetic retinopathy. The corneal autofluorescence of diabetes patients, which was significantly higher than that of healthy controls, correlated significantly with the severity of retinopathy. In addition, the corneal autofluorescence of burned-out retinopathy patients was significantly lower than that of proliferative retinopathy patients. These results suggest that corneal autofluorescence is correlated with retinal ischemia and that corneal autofluorescence can be an indicator of the activity of diabetic retinopathy. Corneal autofluorescence may originate in the accumulation of some factor induced by retinal ischemia within the corneal stroma.

Adult↗
PubMed1995

Clinical evaluation of corneal epithelial barrier function with the slit-lamp fluorophotometer.

We designed a simple and quantitative method for the clinical evaluation of corneal epithelial barrier function using a slit-lamp fluorophotometer and applied it to healthy volunteers and dry-eye patients. The fluorophotometric method used was as follows: Three microliter of 0.5% fluorescein solution was applied to the cornea in the untouched fashion. Ten minutes after instillation, the ocular surface was washed. Twenty minutes afterward, corneal fluorescence intensity was measured and converted into fluorescein concentration. Corneal condition was classified into four grades: no superficial punctate keratopathy (SPK) anywhere on the cornea (grade 0); no SPK at the central cornea (grade 1), mild SPK at the central cornea (grade 2), and severe SPK at the central cornea (grade 3). In the volunteers, corneal condition was classified as grade 0 and fluorescein uptake (ng/ml) was 22.4 +/- 16.9 (mean +/- SD, n = 86). In dry eye, fluorescein uptakes showed significant increase in accordance with SPK severity: grade 1: 96.4 +/- 51.2 (n = 13); grade 2: 318.6 +/- 146.0 (n = 11); and grade 3: 1479.1 +/- 671.9 (n = 10) (each p < 0.0005). This simple method with the slit-lamp fluorophotometer can be used for the clinical grading of SPK in dry eye or other ocular surface diseases.

Adolescent↗
PubMed1995

Proton nuclear magnetic resonance study on the barrier function of pig corneal epithelium and endothelium.

Using gadolinium diethylenetriaminepentaacetic acid (Gd-DTPA) as a tracer, the barrier function of the corneal epithelium and endothelium was evaluated by proton nuclear magnetic resonance. Whole pig eyes and cornea excised with scleral rim, which had been incubated in dextran-added Gd-DTPA solution, were subjected to T1 relaxation measurement and magnetic resonance imaging (MRI). After incubation, the T1 relaxation rate (1/T1) of the excised cornea increased to a steady value, whereas that of the cornea from the whole eye increased only slightly. These results indicated that the increase in the T1 relaxation rate of the excised cornea attributable to Gd-DTPA penetration from the corneal endothelium and that the corneal epithelium exhibited a strong barrier function against Gd-DTPA entry. The MRI study also confirmed the strong barrier, enhanced signals being detected within the aqueous fluid in the T1-weighted image only when the corneal epithelium was abraded. Since Gd-DTPA scarcely penetrates the intact corneal epithelium, Gd-DTPA-enhanced MRI shows potential as a quantitative tracer in evaluating epithelial barrier disruption.

Animals↗
PubMed1994

[Age-related alteration of tear dynamics in normal volunteers].

Age-related alteration of tear dynamics was studied using a newly developed fluorophotometer. The subjects, 55 eyes of 30 normal volunteers, included 32 eyes of 16 younger subjects in their twenties and 23 eyes of 14 older subjects aged 50 years and above. After instillation of 1 microliter of fluorescein solution at a concentration of 50 micrograms/ml into the temporal bulbar conjunctiva, fluorescence intensity was measured with the fluorophotometer every minute for 10 minutes after instillation. Fluorescein concentration was calculated from the intensity, and various parameters of tear dynamics were analyzed. In the younger subjects, the tear volume, initial turnover rate and basal turnover rate were 10.6 +/- 6.0 microliters, 37. 1 +/- 15.6%/min, and 25.8 +/- 15.2%/min, respectively. In the older subjects, these values were 6.5 +/- 2.6 microliters, 26.5 +/- 11.4%/min, and 20.5 +/- 13.5%/min, respectively. The basic tear flow rate, calculated from the basal turnover rate and tear volume, was 2.7 +/- 2.2 microliters/min in the younger and 1.4 +/- 1.0 microliter/min in the older subjects. There was a statistically significant difference in the tear volume, tear turnover rate, and basic tear flow rate between the younger and older subjects.

Adult↗
PubMed1994

Immunohistochemical localization of transforming growth factor-beta 1, -beta 2, and -beta 3 latency-associated peptide in human cornea.

PURPOSE: To study spatial distribution of TGF-beta isoforms (TGF-beta 1, -beta 2, and -beta 3) in the human cornea and to elucidate their biologic roles in corneal maintenance. METHODS: Frozen sections obtained from eight human autopsy eyes were placed on gelatin-coated slides. After blocking of nonspecific binding sites, the slides were incubated with rabbit polyclonal antibody to the latency-associated peptide (LAP) region of human TGF-beta 1, TGF-beta 2, and TGF-beta 3 precursors, followed by the incubation with biotinylated swine anti-rabbit IgG. Subsequently, a streptavidin-labeled alkaline phosphatase technique was used. RESULTS: In the corneal region, beta 1-LAP antibody did not stain either epithelium or stroma, beta 2-LAP antibody stained all epithelial cell layers and the corneal stroma, and beta 3-LAP antibody stained the subepithelial region alone. The staining pattern in the limbal region was almost the same as in the corneal region, except in the limbal stroma, which was stained with beta 1-LAP antibody in three of eight samples. In the trabecular meshwork, all samples showed clear staining with beta 2-LAP antibody, whereas beta 1-LAP and beta 2-LAP antibody stained faintly in five of eight and four of eight samples, respectively. CONCLUSION: beta 2-LAP was found in the corneal epithelium and stroma and beta 3-LAP in the subepithelial region, suggesting that TGF-beta 2 and TGF-beta 3 may play essential roles in normal corneal epithelial maintenance in vivo.

Adult↗
PubMed1994

[A new slit-lamp fluorophotometer for the clinical evaluation of corneal epithelial barrier function].

A new objective slit-lamp fluorophotometer was developed to examine corneal epithelial barrier function. This instrument has several new characteristics. The photodetector system is placed directly in front of the cornea and the focal diamond is accurately positioned at the corneal surface, permitting measurement of the barrier function of peripheral parts of the cornea. Due to the filter characteristics, measurement can be done even in a relatively bright room. Only one second is needed for measurement, eliminating blink interruption. Linear relationships were found between measurement count and fluorescein concentration. 0.5% and 3 microliters of fluorescein was applied to the eyes of healthy volunteers. In non-washed eyes, the concentration changes were consistent with tear turnover, and in washed eyes, the changes reflected the barrier function of the corneal epithelium and showed correlation with age. This instrument is also useful for determining autofluorescence. A significant relation was seen between autofluorescence and age.

Adolescent↗
PubMed1993

[Fluorophotometric measurement of tear volume and tear turnover rate in human eyes].

Tear volume and turnover rate were measured in 31 normal eyes using a newly designed objective fluorophotometer. After instillation of 1 microliter of 50,000 ng/ml fluorescein solution, its concentration in the lower marginal strip was measured every minute for 10 minutes after instillation. The tear volume and the tear turnover rate were determined using the method of Mishima et al. (Invest. Ophthalmol. Vis. Sci., 1966). The tear volume in this study was 12.4 +/- 6.2 microliters, initial turnover rate was 31.5 +/- 14.4%/min., and basal turnover rate was 24.0 +/- 14.2%/min. (Mean +/- SD). There were no significant differences in sex, age or use of contact lens. We also measured the tear volume and turnover rate using 5 microliters of 10,000 ng/ml fluorescein solution in the same way. The result turned out to be significantly higher, suggesting that minimal irritation is required for evaluating the tear flow.

Adult↗
PubMed1990

Population-based case-control study on cancer screening.

Matched case-control studies have recently been used to evaluate the effectiveness of cancer screening. They enable us to estimate the odds ratios of dying of cancer or of getting invasive cancer. The study compares people with various patterns of screening history with those who were not screened. Criteria for eligible cases, controls, and screening histories that are compared as exposures are discussed. The results from a case-control study for evaluating screening for cervical cancer are shown as an example. Also, a study design of a case-control study for evaluating lung cancer screening in Japan is discussed, along with biases and applications of case-control studies in evaluating cancer screening.

Adult↗
PubMed1990

Thyroid hormone excess stimulates the synthesis of proteoglycan in human skin fibroblasts in culture.

We previously demonstrated that proteoglycan accumulated in the affected skin of circumscribed pretibial myxedema of Graves' disease. As an underlying mechanism responsible for the accumulation, we sought to determine whether excess thyroid hormone was partially responsible for the increase in proteoglycan synthesis. Human skin fibroblasts were cultured in Ham's F-10 medium containing 1% Nutridoma with graded doses of T3 (0.184 x 10(-9) to 46 x 10(-9) mol/l) and were labelled with [35S]sulphate and [3H]glucosamine. Proteoglycans were purified by Sephadex G-50, Q-Sepharose chromatography with NaCl-gradient and Sepharose CL-6B chromatography. 35S and 3H incorporated into dermatan sulphate proteoglycan and heparan sulphate proteoglycan and 3H incorporated into hyaluronan were measured. 35S and 3H incorporation into dermatan sulphate proteoglycan was minimum at a T3 concentration of 0.184 x 10(-9) mol/l, and increased with increasing doses of T3 up to 46 x 10(-9) mol/l. 35S and 3H incorporation into heparan sulphate proteoglycan also increased with increasing-doses of T3. 3H incorporation into hyaluronan was not influenced at all by T3. The increased incorporation of 35S into proteoglycan in high-T3 culture reflects the increased synthesis of proteoglycan because 1. the extent of sulphation of disaccharides examined by thin-layer chromatography was not altered by T3; 2. the specific activity of [35S]sulphate was not influenced by T3, and 3. T3 did not decrease the degradation rate of cell-associated proteoglycan.

Adolescent↗
PubMed1988

Characterization of proteoglycans synthesized by rat thyroid cells in culture and their response to thyroid-stimulating hormone.

A Fisher rat thyroid cell line was maintained in culture and the cells were labeled with [3H]glucosamine, [35S]sulfate, and [35S]cysteine to examine the synthesis of proteoglycans. 3H and 35S radioactivity from these precursors were incorporated into both chondroitin sulfate (CS) and heparan sulfate (HS) proteoglycans. CS proteoglycans were almost exclusively secreted into the medium while HS proteoglycans remained mainly associated with the cell layer. Single chain glycosaminoglycans released by papain digestion or alkaline borohydride treatment of either the CS or HS proteoglycans had average molecular weights of approximately 30,000 on Sepharose CL-6B chromatography. Both CS and HS proteoglycans were relatively small and contained only one or two glycosaminoglycans chains. 3H and 35S incorporation into both CS and HS proteoglycans were increased by thyroid-stimulating hormone (TSH) in a dose-dependent manner, which is in part explained by an adenylate cyclase-dependent mechanism as indicated by a similar effect in response to dibutyryl cAMP. TSH enhanced the incorporation of 35S into CS from [35S]cysteine about 1.5-fold and that from [35S]sulfate about 2-fold. This result demonstrated that the increased 35S incorporation from the [35S]sulfate precursor reflects an actual increase in sulfate incorporation and is not simply a result from an apparent increase in specific activity of the phosphoadenosine phosphosulfate donor. Analysis of disaccharides from chondroitinase digests revealed that the proportion of non-sulfated, 4-sulfated, and 6-sulfated disaccharides was not altered appreciably by TSH. These results, together with the disproportionate increase in 3H incorporation into CS from [3H]glucosamine, indicated that TSH increased the specific activity of the 3H label as well. Chase experiments revealed that CS proteoglycans were rapidly (t1/2 = 15 min) secreted into the medium and that the degradation of cell-associated proteoglycans was enhanced by TSH.

Animals↗
PubMed1988

A case-control study of the effectiveness of cervical cancer screening in Osaka, Japan.

In the small town of Nose in Osaka, Japan, a population-based screening program for cervical cancer by Papanicolaou smear has been conducted since 1965. In order to evaluate the effectiveness of screening in terms of the reduction of the mortality and the incidence of invasive cervical cancer, two types of case-control studies were carried out. In the first study, the case series consisted of all women who died of cervical cancer under 80 years of age at the time of diagnosis in 1965-1987 (N = 15). For each case, 10 controls were chosen from living residents, matched by year of birth. It showed that the odds ratio (OR) of dying of cervical cancer for screened versus non-screened women was 0.22 (95% CI = 0.03-1.95). In the second study, the case series consisted of all women who were diagnosed as having invasive cancer under 80 years of age at the time of diagnosis in the same period (N = 28). For each case, 10 controls were chosen from living residents without invasive cancer, matched by year of birth and according to whether or not they were screened at the year of the diagnosis of the matched case. It showed that the OR of getting invasive cancer for screened versus non-screened women was 0.41 (95%CI = 0.13-1.29). From these results, it was estimated that 78% of cervical cancer mortality and 59% of invasive cervical cancer incidence among non-screened women could be prevented by cervical cancer screening.

Adult↗