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Biomedical subjects

A Kanai

Publications and source records attributed to A Kanai.

At least 19 recordsLinked to original sources
PubMed1995

Poly(U) binding activity of hepatitis C virus NS3 protein, a putative RNA helicase.

A non-structural protein of the hepatitis C virus (HCV), NS3, contains amino acid sequence motifs characteristic of serine-proteinases and RNA helicases. RNA binding activity of the NS3 protein with an apparent dissociation constant of 2 x 10(-7) M was detected using a poly(U)-Sepharose resin. Competitive RNA binding analysis suggested that the NS3 protein binds preferentially to the poly(U) sequence, which is located at the 3' end of HCV RNA. Mutational analysis of NS3 protein revealed the possibility that both the RNA helicase region and the serine-proteinase region were necessary for full RNA binding activity.

Amino Acid Sequence↗
PubMed1995

Clinical and histopathologic features of corneal dystrophies in Japan.

PURPOSE: To examine retrospectively the frequency of various corneal dystrophies among Japanese patients who underwent keratoplasty or keratectomy at the authors' institution over a 34-year period, and to compare the histopathologic features of these disorders in the Japanese population with those reported in the Western literature. METHODS: Corneal specimens obtained during keratectomy or keratoplasty (lamellar and penetrating) performed at the authors' institution from 1959 through 1992 were reviewed. Immunohistochemical studies were performed using monoclonal antibodies to keratan sulfate and gelsolin, as well as two lectins (concanavalin A and wheat germ agglutinin). RESULTS: Of 1259 corneal specimens, 159 (12.6%) specimens from a total of 80 patients showed corneal dystrophy. Virtually all were non-Fuchs dystrophies; only one case of primary Fuchs dystrophy was identified histologically. Granular dystrophy and gelatinous drop-like dystrophy were the most common dystrophies identified in the specimens, largely because of multiple specimens from individual patients with recurrent disease. These two disorders accounted for 86 of the 159 specimens. In terms of numbers of patients, lattice dystrophy was the most common (26 patients, 32.5%), followed by macular dystrophy (16 patients, 20%), gelatinous drop-like dystrophy (15 patients, 18.8%), granular dystrophy (14 patients, 17.5%), and Avellino dystrophy (3 patients, 3.75%). Dystrophies represented by only one or two patients included congenital hereditary endothelial dystrophy, primary spheroidal keratopathy, posterior polymorphous dystrophy, Schnyder crystalline dystrophy, and Fuchs dystrophy. CONCLUSIONS: This histopathologic study showed a very low incidence of Fuchs dystrophy in the authors' Japanese patient population, compared with the incidences seen in studies of populations in Western countries. Of the non-Fuchs dystrophies, lattice dystrophy was the most common among the patients, although there were large numbers of specimens with granular dystrophy and gelatinous drop-like dystrophy due to their recurrent character. The causes of clinical and histopathologic differences and similarities among the Japanese patients and the patients described in the Western literature are likely related to genetic factors, but a complete understanding of their specific mechanisms awaits future molecular biologic and genetic elucidation.

Antibodies, Monoclonal↗
PubMed1995

Optical mapping reveals that repolarization spreads anisotropically and is guided by fiber orientation in guinea pig hearts.

Guinea pig hearts were stained with a voltage-sensitive dye and imaged on a photodiode array to record fluorescent action potentials (APs) from 124 sites. Activation and repolarization patterns were recorded from the epicardium during stimulation at different loci and correlated with the underlying fiber architecture. Endocardial APs were recorded by inserting a light guide into the ventricular cavity or by dissecting out the ventricular free wall to expose the endocardium. In hearts paced on the right atrium to simulate sinus rhythm, activation emerged synchronously over a large area of the ventricular epicardium and spread laterally in 5 to 7 ms. The apparent longitudinal and transverse velocities were 2.66 +/- 0.11 and 1.65 +/- 0.09 m/s (n = 12). In contrast, repolarization began near the apex on the endocardium and spread transmurally in 6 +/- 1.3 ms (n = 12) and then anisotropically along the epicardium in 25 to 30 ms with apparent maximum (0.53 +/- 0.11 m/s) and minimum (0.31 +/- 0.10 m/s) repolarization velocities that aligned with the longitudinal and transverse axes of epicardial fibers. When paced on the epicardium, activation of intact hearts (n = 12) and perfused sheets (n = 8) was anisotropic, with longitudinal (0.85 +/- 0.05 m/s) and transverse (0.44 +/- 0.04 m/s) conduction velocities that aligned with the epicardial fiber orientation. When activation was initiated at different sites on the epicardium, repolarization always began near the apex and exhibited patterns similar to those obtained under right atrial pacing, but with slower longitudinal (0.41 +/- 0.09 m/s) and transverse (0.23 +/- 0.07 m/s) repolarization velocities (n = 18). In sheets stretched parallel to the longitudinal axis of surface fibers, AP durations (APDs) increased as a function of fiber length, from the length at zero developed tension to 120% of the length at maximum developed tension (Lmax). Spatial distributions of APDs did not change during stretches along the rising phase of the length-tension curve. In sheets stretched to 50% of Lmax, APDs were shorter and more homogeneous on the endocardium (mean APD, 188 ms; delta APD, 195-186 = 9 ms) than on the epicardium (mean APD, 204 ms; delta APD, 212-186 = 26 ms; n = 8). In guinea pig hearts, activation is rapid; therefore, repolarization depends primarily on intrinsic spatial heterogeneities of APDs. Consequently, repolarization begins at endocardial cells with the shortest APDs and spreads transmurally and then anisotropically on the surface according to the epicardial cell orientation.

Animals↗
PubMed1995

Clinical features of Japanese Leber's hereditary optic neuropathy with 11778 mutation of mitochondrial DNA.

The G to A transition of nucleotide position (nt) 11778 of mitochondrial DNA (mtDNA) has been frequently observed in Japanese Leber's hereditary optic neuropathy (LHON) cases. Therefore, we performed a multi-institutional study in Japan of LHON cases with this 11778 mutation of the mtDNA. Genetic and clinical data on 108 cases (90 affected and 18 carriers) in 79 unrelated families were obtained from 64 Japanese institutions. Detection of the nt11778 mutation was performed using restriction enzymes (74 cases) or dot blot with allele specific oligonucleotide (34 cases). Heteroplasmy was observed in 13 of the 90 affected cases and in 8 of the 18 carrier cases. Forty-five families had family history of LHON (44 maternal inheritance, 1 undetermined), and in 28 families (35.9%) there were isolated cases. The male-to-female ratio in the affected was 82:7 (92.1% male). The age at onset of visual loss ranged from 7 to 59 years (average: 23.4 years). All cases had bilateral involvement except one case with a blind eye resulting from ocular infection during childhood. Onset interval between the two eyes ranged from simultaneous to 17 months (average: 2.5 months), in 91.3% of cases being under 6 months. Visual acuity was 0.1 or worse in 152 (85.9%) of 177 eyes, only 6 eyes showing over 0.5. Progression of visual loss ranged from 0 to 48 months (average: 6.2 months). Central visual field abnormality was observed in 162 eyes (96.4%) of 168 eyes. Nonsuspect fundus in the ophthalmoscopic examination constituted 22.8% of eyes. Systemic corticosteroid was given to 45 (52.9%) of 85 cases and visual acuity was improved in only 2 cases (4.4%). Arrhythmia, neurological and muscular abnormality were observed as rare general complications. The present survey indicates that the male-to-female ratio is higher than the previous Japanese LHON statistics and that the visual outcome is better than in American LHON cases with the 11778 mutation.

Adolescent↗
PubMed1995

[Correlation between corneal sensitivity and nerve regeneration following excimer laser ablation].

To compare the recovery of corneal sensitivity and corneal regeneration following excimer laser and manual epithelial debridement, the corneal epithelium of the right eye of New Zealand white rabbits (n = 21) was manually debrided and the left eye was ablated with the excimer laser (47 microns depth, 5 Hz, and 160 mJ/cm2). We observed the wound healing rate and corneal sensitivity. The relative density of innervation on the intraepithelial layer was measured using gold chloride staining or right microscopic examination for 30 weeks. In the laser-ablated cornea sensitivity rapidly increased to a normal level by day 5, and then it continued to increase gradually and reached a maximum at day 42. Thereafter it remained elevated to 126 days and returned to normal at 210 days. There were significant differences in the recovery of sensitivity following excimer ablation and manual epithelial removal. The relative density of innervation on the intraepithelial layer after excimer ablation was significantly higher than manual debridement at day 35. We observed a correlation between increased sensitivity levels and increased nerve density. This result suggests that for photorefractive keratectomy or phototherapeutic keratectomy, manual debridement of the corneal epithelium should be performed before stromal excimer ablation.

Animals↗
PubMed1995

[Incidence of tumors and tumor-like lesions in the conjunctiva and the cornea].

Incidence of tumors and tumor-like lesions in conjunctiva and cornea seen at Juntendo University during the 13-year period from 1980 to 1992 was analysed histopathologically. There were 126 cases including 116 benign (92.1%) and 10 malignant lesions (7.9%). Pigmented nevi (32 cases) were most frequently found, accounting for 27.6% of the benign tumors and tumor-like lesions, half of which were compound nevi (16 cases). Nevi were closely followed by cysts (24 cases, 20.7%) and dermoids (15 cases, 12.9%). Carcinoma in situ (3 cases) was most frequently found, accounting for 30% of the malignant tumors (10 cases), closely followed by malignant lymphoma (2 cases), squamous cell carcinoma (2 cases), mucinous carcinoma (1 case), sebaceous gland carcinoma (1 case) and metastatic tumor (1 case). The ratio of males to females was 4:6. Age distribution of the patients was 47-92 years.

Adolescent↗
PubMed1995

[Clinical importance of inclusion cysts of nevi in bulbar conjunctiva].

We investigated 30 cases of nevi in bulbar conjunctiva histopathologically from 1980 to 1992. The patients' ages were between 5 and 85 years old (mean, 21 years). Investigated parameters of the tumors were the location, growth pattern, and the presence of inclusion cysts, melanin granules, goblet cells, and feeding vessels. Of 30 cases, 26 cases (87%) had inclusion cysts which were characteristic findings of conjunctival nevi. The mucous secretion from goblet cells may play an important role in the synthesis of inclusion cysts, but goblet cells were not found in 9 cases. This finding suggests that other secretory cells may be present. Four cases without inclusion cysts consisted of flat tumors. From this finding, the presence of inclusion cysts may be related to the growth of tumors. We conclude that the growth of the pigmented conjunctival tumors with inclusion cysts suggests a benign growth pattern. A periodical follow-up study or biopsy should be performed, if inclusion cysts are not found.

Adolescent↗
PubMed1995

Development of a new soft gas permeable contact lens with Dk 300.

The effects on the rabbit cornea of a new gas permeable nonhydrophilic soft contact lens made of newly designed polymer with a Dk value of 300 were studied physiologically, histologically, and histochemically during 5 days of daily wear followed by 14 days of extended wear. Corneal swelling was observed to be within 10% of corneal thickness during the wear period. No serious corneal surface changes were observed. Specular microscopy showed no endothelial changes in terms of cell density, coefficient of variation of cell area (CV), or hexagonality before and 2 weeks after lens wear. Histochemical study using periodic acid-Schiff staining and histological study with hematoxylin-eosin revealed no remarkable changes. Scanning electron microscopy revealed slight focal changes; there were no significant changes. The results show that the new soft gas permeable contact lens has no harmful effect on the rabbit cornea.

Animals↗
PubMed1994

Acute retinal necrosis syndrome associated with herpes simplex keratitis.

BACKGROUND: Although acute retinal necrosis (ARN) syndrome is caused by a herpes group virus, association of herpetic keratitis with ARN syndrome is uncommon. A case of unilateral ARN syndrome with herpes simplex keratitis is discussed. METHODS: A 40-year-old man developed unilateral keratitis, necrotic retinitis, retinal vasculitis, vitritis, and iritis consistent with ARN syndrome 1 month after treatment for ipsilateral facial nerve palsy and auricular herpetic vesicles (Tolosa-Hunt syndrome). Impression cytologic examination of the corneal epithelial ulcer that developed concurrent with the intraocular findings and of the aqueous humor (obtained by paracentesis) was performed. RESULTS: Cells that reacted with anti-herpes simplex virus type 1 (HSV-1) antibody were detected on impression cytology, and DNA fragments corresponding to the HSV-1 DNA sequence were detected in the aqueous humor. CONCLUSION: This case shows that ARN syndrome may, on rare occasions, be associated with herpes keratitis secondary to HSV-1.

Adult↗
PubMed1994

Subthreshold stimulation of Purkinje fibers interrupts ventricular tachycardia in intact hearts. Experimental study with voltage-sensitive dyes and imaging techniques.

The effects of subthreshold stimulation (STS) delivered during right atrial pacing and ventricular tachycardia (VT) were investigated in Langendorff-perfused guinea pig hearts. The hearts were stained with a voltage-sensitive dye (RH 421) to map the propagation of optical action potentials. Sustained VT was reliably induced by 5-second trains (cycle length [CL], 25 to 50 milliseconds; duration, 0.5 to 10 milliseconds; and voltage, 2x threshold voltage) of impulses (n = 12 hearts) or a single premature beat (n = 6). The location of extrastimuli was not critical to the induction of VT, but the diameter of the heart had to be > or = 14.5 mm. During VT, heart rate increased from 200 to 600 beats per minute; action potential durations decreased from 112 to 175 milliseconds to 60 to 105 milliseconds, with no diastolic interval. Activation on the epicardium spread anisotropically, but VT decreased the "apparent" maximum conduction velocity (theta max) by 68% and altered the orientation of the major axis from beat to beat. Activation patterns and theta max measured during VT were similar to patterns recorded during direct pacing of the ventricle and indicated that Purkinje fibers no longer propelled ventricular excitation. STS (CL, 25 to 50 milliseconds; duration, 0.5 to 25 milliseconds; and voltage, 0.5x to 0.8x threshold; trains of 2.0 to 2.5 seconds) interrupted VT when applied to Purkinje fibers lining the endocardium (n = 6) but failed to interrupt VT when applied to the epicardium (n = 8). In atrial pacing, STS delivered to the endocardium increased theta max from 2.44 +/- 0.32 (mean +/- SEM) to 3.63 +/- 0.21 m/s in a local region surrounding the first activation sites (n = 4). Alternatively, VT could be terminated by reducing theta max (approximately 55%) with procainamide (10 mumol/L) (n = 6). STS terminates VT by synchronizing ventricular excitation most likely by increasing local conduction and/or improving the coupling between Purkinje and ventricular cells.

Action Potentials↗
PubMed1994

[Career stress model among working women: examining the determinants of turnover and quitting based on path analysis].

For the purpose of examining the determinants of turnover and quitting among working women, 283 working women were sampled from several private corporations in Japan. The causal relation model was named "Career Stress Model among Working Women" since it involved, among others, unique job stressors for working women. The results of path analysis showed that among women, the higher the stressors due to sex discrimination in working spaces, the higher the turnover. Further, the results showed that the lower the job commitment, the higher the quitting. However, since job commitment increases with corporate eagerness towards development of women's careers, corporate efforts to remove all elements of sex discrimination and efforts to implement policies which assist development of women's careers were considered to be important in reducing turnover and quitting among working women.

Adolescent↗
PubMed1993

Clinical features of autosomal dominant retinitis pigmentosa with rhodopsin gene codon 17 mutation and retinal neovascularization in a Japanese patient.

A 49-year-old Japanese man had autosomal dominant retinitis pigmentosa with a point mutation in codon 17 of the rhodopsin gene, resulting in a threonine-to-methionine change, and retinal neovascularization in both eyes. Pigmentary degeneration mainly in the inferior area of the fundus, and severe loss in the upper portion of the visual field were observed. Moderately preserved rod and cone functions were demonstrated by electroretinograms. These findings differed from those of Japanese and white patients with autosomal dominant retinitis pigmentosa with a codon 347 mutation and were almost the same as those of white patients with the codon 17 mutation. Our study indicates that phenotypic similarities exist among patients with the same mutation, but of different racial backgrounds. The neovascularization in the right eye diminished over a two-year period in conjunction with the progression of retinal degeneration.

Adaptation, Ocular↗
PubMed1993

A multicenter study of typical retinitis pigmentosa in Japan.

A nationwide, multicenter study of typical retinitis pigmentosa was carried out in collaboration with 13 university hospitals throughout Japan. A total of 253 patients, 122 males and 131 females, with a wide range of ages (mean 48 years), were registered during a two-month period in 1989. Determination of inheritance pattern revealed 30.2% autosomal recessive cases, 15.4% autosomal dominant, 0.5% X-linked, and 48.9% simplex, indicating a relative decrease in autosomal recessive cases and a relative increase in simplex cases in recent decades. The age at onset, initial symptom, and visual functions including visual acuity, visual field and electroretinogram showed a marked interindividual variability, but statistical analysis demonstrated that visual defects progressed with increasing age and disease duration. A correlation between the phenotypic variation and the genetic type was observed. This survey of retinitis pigmentosa in Japan provides information for counseling and rehabilitation of patients and encourages basic and clinical research of this genetic disease.

Adolescent↗
PubMed1992

A Japanese pedigree of autosomal dominant congenital stationary night blindness with variable expressivity.

Three cases in three successive generations of one family with autosomal dominant congenital stationary night blindness are presented. Case 1, the proband, and Case 3, his grandfather had the same electroretinographic responses: nonrecordable scotopic electroretinogram (ERG), normal but slightly diminished flicker ERG, and negative-shaped single bright-flash ERG. Their dark adaptation curves were monophasic with no rod segment. However, Case 2, the proband's father, showed different ERG findings; a moderately diminished scotopic ERG, a normal flicker ERG, and a biphasic dark adaptation curve with an elevated final rod threshold. The authors believe that these differences reflect variations in the expressivity of a single gene mutation with the lowest expressivity being seen in Case 2.

Adult↗
PubMed1992

[The immunosuppressive effects of 0.025% cyclosporin eye drops in alpha cyclodextrin on rabbit corneal allografts].

We reported the ocular penetration of cyclosporin (CYA) and the immunosuppressive effect of rabbit corneal allograft using 0.025% CYA eye drops in alpha-cyclodextrin (alpha-CD). Local application using 0.025% CYA in alpha-CD showed the concentration of 4,133 ng/gr in the cornea, but no detectable levels in aqueous humor and serum. All eyes (10/10) in the CYA eye drop group remained clear for 100 days after corneal allografting. CYA eye drops halted and suppressed the corneal allograft's immune reaction when the treatment was begun early in the initial phase of rejection. These results indicate that 0.025% CYA eye drops in alpha-CD penetrate the cornea 5 to 10 times more than CYA eye drops in lipophilic vehicles. Furthermore, they are extremely effective in suppressing the immune reaction of corneal grafts.

Animals↗
PubMed1992

[An epidemiogenetic study of typical retinitis pigmentosa in Japan--a preliminary report of nationwide, multicenter study].

We performed a nationwide, multicenter study of typical retinitis pigmentosa with reference to the inheritance patterns of the disease. A total of 253 probands were registered during two months of 1989, and an analysis of the parental consanguinity of 182 probands with the method of inbreeding coefficient enabled us to estimate the relative prevalence of genetic types; autosomal recessive trait: 47.6%; autosomal dominant trait: 17.3%; sporadic cases: 34.6%. A comparison of the results with previous studies has indicated a decrease in the prevalence of the autosomal recessive trait and an increase in the sporadic cases, as would be expected from the decrease in consanguineous marriages and offsprings in the past few decades in Japan. X-linked retinitis pigmentosa was rarely identified, but precise evaluation of its frequency needs further investigation.

Adolescent↗
PubMed1992

[Molecular biological study of the rhodopsin gene in Japanese patients with autosomal dominant retinitis pigmentosa].

The author analyzed codon 347 of the rhodopsin gene using PCR (polymerase chain reaction) amplification and restriction enzymes in 19 unrelated Japanese families including 28 patients with autosomal dominant retinitis pigmentosa (ADRP). An allele of codon 347 mutation was found in a family (father and daughter). Sequence analysis shows that the mutation is from CCG to CTG. This mutation appears to be the cause of one form of ADRP, since it was also found in Japanese cases of ADRP which have a different racial background from families reported by Dryja et al.

Codon↗