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Biomedical subjects

Y Obara

Publications and source records attributed to Y Obara.

At least 73 records · Page 4Linked to original sources
PubMed1998

[Clinical results of three types of intraocular lenses for small incision surgery].

We implanted three types of intraocular lens (IOL) in 30 eyes each by small-incision surgery. They were: foldable acryl IOL, foldable silicone IOL and polymethylmethacrylate (PMMA) IOL. We evaluated the following items during three years after surgery: visual acuity, astigmatism, glare disability, contrast sensitivity, tilt and decentering of IOL, corneal endothelial population, aqueous flare and aftercataract. Eyes foldable IOLs were more excellent than PMMA IOLs regarding visual acuity, astigmatism and aqueous flare which are indices for the early postoperative period. PMMA and acryl IOLs were more excellent than silicone IOLs regarding decentration of IOL and aftercataract which are indices for the late postoperative period.

Acrylates↗
PubMed1997

A Turner syndrome woman with a ring X chromosome [45,X/46,X,r(X)(p22.3q27)] whose child also had a ring X chromosome.

OBJECTIVE: To describe a woman with Turner syndrome with ring X chromosome mosaicism who had a child who possessed the same ring X chromosome. DESIGN: Polymorphisms of genes located on the X chromosome from genomic DNA of the mother, father, and the child were evaluated. PATIENT(S): The mother's karyotype was 45,X [48]/46,X,r(X)(p22.3q27) [2], and the child's karyotype was 45,X[33]/46,X,r(X)(p22.3q27) [17]. INTERVENTION(S): Polymerase chain reaction was used to amplify short tandem repeats from the loci of the hypoxanthine phosphoribosyltransferase gene and the androgen receptor gene. RESULT(S): Alleles for both genes in the child originated from both parents in a heterozygous fashion. The alleles originating from the mother originated from the ring X chromosome. However, the amount of amplified DNA was less than that of a normal X chromosome. CONCLUSION(S): The ring X chromosome of the mother was most likely transmitted to the newborn. Thus, an ovum with the ring X chromosome can be fertile and can produce a viable zygote.

Adult↗
PubMed1997

Non-insulin- and insulin-mediated glucose uptake in dairy cows.

Four mid-lactation Holstein dairy cows (mean milk yield on day of experiments 26.1 kg/d) were used in a series of experiments to establish the contribution of non-insulin-mediated glucose uptake to total glucose uptake at basal insulin concentrations. A secondary objective was to determine whether somatostatin affects the action of infused insulin. In part I of the experiment a primed continuous infusion [6,6-2H]glucose (45.2 micrograms/kg per min) was begun at time 0 and continued for 5 h. After 3 h of [6,6-2H]glucose infusion (basal period) a primed continuous infusion of insulin (0.001 i.u./kg per min) was administered for 2 h. Coincidental with the insulin infusion, normal glucose was also infused in order to maintain the plasma glucose concentration at euglycaemia. Part II of the experiment was the same as part I except that somatostatin was infused for 2 h (0.333 micrograms/kg per min) instead of insulin. In part III of the experiment both insulin and somatostatin were infused for the final 2 h. Plasma insulin levels were increased by insulin infusion (to 0.1476 to 0.1290 i.u./l for parts I and III respectively) and were reduced by somatostatin infusion in part II (to 0.006 i.u./l) relative to the basal periods (mean 0.021 i.u./l). Glucose uptake during somatostatin infusion (2.50 mg/kg per min; part II) was 92.0% of that observed in the respective basal period (2.72 mg/kg per min). Circulating insulin levels were much lower than the dose of insulin that causes a half maximal effect on glucose uptake (0.06-0.10 i.u./l for ruminants); consequently insulin-mediated glucose uptake was probably absent in part II. Secondly, glucose uptake following insulin only infusion (4.05 mg/kg per min) was significantly lower than that observed when insulin plus somatostatin was infused (4.69 mg/kg per min), indicating that somatostatin either directly or indirectly enhanced the action of insulin on glucose uptake.

Animals↗
PubMed1997

Acute myelogenous leukaemia with t(8;21) translocation of normal cell origin in mosaic Down's syndrome with isochromosome 21q.

We report a 13-year-old girl with Down's syndrome (DS) having a mosaic karyotype of 46,XX/46,XX, -21,+i(21q), who developed acute myelogenous leukaemia (AML) (FAB M1). The t(8;21) translocation generating a AML1/MTG8 chimaeric gene of her blasts was demonstrated by cytogenetic analysis and reverse transcription-polymerase chain reaction. Interestingly, the leukaemic clone with t(8;21) did not have isochromosome 21q, indicating that the blasts were of normal cell origin. These findings suggest that, in older patients with DS, 21 trisomy cells have no greater predisposition to develop AML than normal karyotypic cells.

Adolescent↗
PubMed1997

Growth hormone does not affect non-insulin-mediated glucose uptake in sheep.

Four adult Merino sheep were used in the experiment, which was divided into four parts. For the 5 days before parts 1 and 3 saline was injected and for the 5 days before parts 2 and 4 growth hormone (GH; 4 mg day-1 subcutaneously) was injected. In parts 1 and 2 a primed continuous infusion of [6,6-2H2]glucose and either saline or GH, respectively, were infused for 5 h. The first 3 h was the control period. From 3 to 5 h insulin (0.5 mU kg-1 min-1) was infused. Coincident with the insulin infusion, normal glucose was also infused at a variable rate, dependent on the rapidly determined plasma glucose concentration, in order to keep the plasma glucose concentration constant. Parts 3 and 4 of the experiment were the same as parts 1 and 2, respectively, except for the following: the glucose isotope and saline or GH were infused for 7 h, from 3 to 7 h somatostatin (SRIF; 0.417 microgram kg-1 min-1) was infused, and from 5 to 7 h insulin was infused. Measurements of glucose turnover were made in the last 40 min of the control, insulin-only, SRIF-only and insulin-plus-SRIF infusion periods. Plasma insulin levels were reduced to below the level of detection by the SRIF infusion; under such conditions whole body glucose uptake should be entirely non-insulin mediated (NIMGU). Expressing glucose uptake as glucose metabolic clearance rate revealed that GH had no effect on NIMGU but significantly reduced the level of insulin-mediated glucose uptake (IMGU). Thus a reduction in the rate of NIMGU is probably not part of the mechanism by which GH repartitions glucose to sites of growth and milk production, whilst the present study confirms the antagonistic effect of GH on IMGU.

Animals↗
PubMed1997

Intraocular lens durability after a mean of 10.9 years' implantation in humans.

AIMS/BACKGROUND: To clarify whether intraocular lens (IOL) implantation in the human eye affects the durability of polymethylmethacrylate over an average period of 10.9 years. METHODS: Shearing stress and extent of damage following neodymium (Nd):YAG laser application to 18 study and 12 control optics were examined. RESULTS: No significant difference was found between the study and the control IOLs in shearing stress and extent of damage following Nd:YAG. CONCLUSION: An average 10.9 years' implantation in humans does not affect either the shearing stress or extent of damage following Nd:YAG shots of polymethylmethacrylate.

Humans↗
PubMed1997

Delayed response of QM- and DA/DAPI-fluorescence in C-heterochromatin of the small Japanese field mouse, Apodemus argenteus.

The small Japanese field mouse Apodemus argenteus has the diploid chromosome number of 46, carrying rather large centromeric C-heterochromatin in most of the 44 autosomes and a large amount of C-heterochromatin in the sex chromosomes: the largest subtelocentric X was heterochromatic in almost two-fifth (whole short arm and proximal part of the long arm) of its entire length and the medium-sized acrocentric Y was totally heterochromatic. The C-heterochromatin (C-positive) areas, other than those of the Y and smallest three pairs, had a unique property of "delayed QM-fluorescence", which has not been reported to-date, showing dull QM-fluorescence immediately after exposure to blue light (BL), but gradually turning to bright fluorescence in a few minutes. The fluorescence intensity gradually decreased after attaining its peak, and finally became extinct. A similar pattern of fluorescence was also obtained in DA/DAPI-stained-X chromosome C-heterochromatin, but not in autosomal C-heterochromatin. No such dull-to-bright transition of QM-fluorescence could be obtained by CMA staining, for which the C-positive areas were apparently negative even after overexposure to BL. These facts indicate that the C-positive areas of A. argenteus showing dull-to-bright transition of QM-fluorescence contain A-T rich DNA. The delayed QM-fluorescence was found only in A. argenteus, in thirteen mammalian species so-far examined. Furthermore, this unique property of QM-fluorescence could be artificially altered to non-delayed ordinary type of fluorescence by sequentially pretreating the fixed chromosomes with hydrochloride and barium hydroxide solutions. The cytological implication of the delayed fluorescence in the C-heterochromatin of A. argenteus is briefly discussed.

Animals↗
PubMed1997

Distribution of herpes simplex virus types 1 and 2 genomes in human spinal ganglia studied by PCR and in situ hybridization.

Clinical data indicate that the recurring herpes simplex virus (HSV) from oro-labial lesions is HSV subtype 1 and that the virus from genital lesions is HSV-2. This suggests that HSV-1 and HSV-2 reside in latent forms in the trigeminal ganglia and sacral ganglia, respectively. However, the distribution of latent HSV-1 and HSV-2 infections in human spinal ganglia has not been fully examined. This report concerns the application of polymerase chain reaction (PCR) and in situ hybridization (ISH) to such a study. By using PCR and employing the respective primers, HSV-1 and HSV-2 DNAs were detected in 207 of 524 samples from 262 spinal ganglia (from the cervical to the sacral ganglia) examined on both sides. The percentages of HSV-1 and HSV-2 detected in a given set of ganglia were similar, indicating an absence of site preference. By ISH, few but positive hybridization signals were detected evenly in sacral ganglia sections. The data suggest that regional specificity of recurrent HSV infections is not due to regional distribution of latent virus, but that local host factors may be important for recurrences.

Adult↗
PubMed1996

Cancer-associated retinopathy with presumed vasculitis.

PURPOSE: To treat a 63-year-old woman who experienced fairly rapid vision loss in association with small-cell carcinoma of the lung. METHODS: She underwent a full ophthalmologic examination, including fluorescein angiography and an immunologic study by Western blot analysis. RESULTS: Fluorescein angiography demonstrated diffuse staining of the retinal vessels. She had 62-kd antiretinal antibody in her serum. Cancer-associated retinopathy was diagnosed. CONCLUSION: The staining seen on the angiogram appears to indicate vasculitis, which would cause the characteristic attenuation of retinal vessels in this disease.

Anti-Inflammatory Agents↗
PubMed1996

Efficacy of Cafon gel on cutaneous infection with herpes simplex virus (HSV)-2 and acyclovir-resistant HSV in mice.

Caffeine is known to inhibit replication of herpes simplex virus (HSV)-1 and the therapeutic efficacy of caffeine (Cafon) gel has been shown in a mouse model cutaneously infected with HSV-1. In this study we examined the inhibitory effect of caffeine on infection with HSV-2 and acyclovir-resistant HSV-1 strains, thymidine kinase (TK)-deficient and phosphonoacetic acid (PAA)-resistant HSV-1 in vitro and in vivo. Caffeine inhibited plaque formation of HSV-2 and acyclovir-resistant HSV-1 strains and their EC50 values ranged from 0.42 to 1.11 mg/ml. Topical treatment with Cafon gel was significantly effective in retarding the development of skin lesions caused by cutaneous infection with HSV-2 and PAA-resistant HSV-1 and in reducing the virus yield of the skin infected with TK-deficient HSV-1. The results suggested that Cafon gel would be useful for the topical treatment of cutaneous infection with HSV-2 and acyclovir-resistant HSV strains.

Acyclovir↗
PubMed1996

Trisomy 18 mosaicism associated with secondary amenorrhea: ratios of mosaicism in different samples and complications.

A 28-year-old woman who complained of irregular menstruation was diagnosed as suffering from trisomy 18 mosaicism. She was karyotyped because of her characteristic face, mild mental retardation and aberrant hyperpigmentation of the skin. Her motor function was within normal range. Physical and laboratory examinations, however, revealed obesity, short stature, minor anomalies of the fingers, many areas of hyperpigmentation on the trunk and the hips, hypergonadotropinemia, diabetes mellitus, liver dysfunction, and hyperlipidemia. The ratios of normal/trisomy 18 were 4:135 in blood lymphocytes, 3:11 in a hyperpigmented area of the skin, 20:0 in a normally pigmented area of the skin, and 14:6 in ascitic cells. Laparoscopy revealed that her ovaries contained neither follicles nor germ cells.

Abnormalities, Multiple↗
PubMed1996

Retinal melatonin is not involved in corneal mitotic rhythms in the Japanese quail: effects of formoguanamine hydrochloride and eye-lid suture.

Relation between retinal melatonin and corneal mitotic rhythms in the Japanese quail was investigated in experiments manipulating the ocular physiology by treatments with formoguanamine hydrochloride (FG) and eye-lid suture. In experiment 1, we investigated the effects of FG, which is known to induce photoreceptor degeneration, on retinal melatonin and corneal mitotic rhythms. FG-treatment completely abolished the retinal melatonin rhythms in both LD 12:12 and constant darkness (DD), but the corneal mitotic rhythm was maintained with high mitotic rate in darkness under a LD cycle and subjective night under DD. The result suggests that 1) the photoreceptor cells in the retina are the site for melatonin production and/or for the oscillator which drives the circadian rhythm in retinal melatonin, and 2) melatonin is not involved in generation of the corneal mitotic rhythm. In experiment 2, we investigated the effects of eye-lid suture, which is known to induce eye enlargement and bulgy cornea, on the retinal melatonin and corneal mitotic rhythms. Eye-lid suture abolished the corneal mitotic rhythm in both LD and DD, with a high mitotic rate being maintained throughout 24 hr. But retinal melatonin maintained its rhythm with high levels in darkness under a LD cycle and in subjective night under DD. The result suggests that 1) bulgy cornea in the sutured eye was induced by the increase in mitotic rate in the light period, and 2) disappearance of the corneal mitotic rhythm does not have a relation to retinal melatonin. These results suggest that retinal melatonin is not involved in generation of the corneal mitotic rhythm and that there are two circadian clock systems in the eye.

Animals↗
PubMed1996

Distributional change of alpha-tocopherol in the rat lens with age.

Concentration of alpha-tocopherol (alpha-Toc.) in the rat lens (1, 4 and 12 months old) was determined in single lenticular layers using gas chromatography and mass spectrometry. The highest concentration of alpha-Toc. in lens was found in the nucleus, followed by the deeper anterior and deeper posterior cortices, the shallow anterior and shallow posterior cortices, and the equatorial region. The topographic alpha-Toc. distribution in the lens did not differ between lenses of 1-, 4- and 12-month-old rats. A significant decrease of alpha-Toc. concentration was seen in lenses of 4- and 12-month-old rats compared to those 1 month old. Concentration and distribution in 4- and 12-month-old rat lenses were almost the same. The concentration of alpha-Toc. in the lens changes in relation to age.

Aging↗
PubMed1996

Effect of growth hormone-releasing factor on the response to insulin of cows during early and late lactation.

The euglycemic clamp technique was used to determine the effect of bovine growth hormone-releasing factor on glucose kinetics and on the response to insulin of 4 dairy cows during early lactation (mean, 35 d postpartum) and of 6 dairy cows during late lactation (mean, 194 d postpartum). Beginning 3 d prior to experiments, cows were injected twice daily with either saline or 2.5 micrograms/kg of growth hormone-releasing factor. On the day of the experiment, saline or the releasing factor (0.0119 microgram/kg per min) was infused into each cow for 5 h. After a basal period, insulin was infused at 1 and then at 6 mU/kg per min; plasma glucose concentrations were maintained at basal concentrations by the infusion of normal glucose. Growth hormone-releasing factor reduced the glucose infusion rate that was required to maintain euglycemia during the insulin infusions during late lactation but had no effect during early lactation. During the insulin infusions of the late lactation experiment only, the rates of glucose appearance, disappearance, and metabolic clearance were lower when plasma growth hormone was elevated. The results demonstrated that elevated concentrations of growth hormone decreased the responsiveness of peripheral tissues to high concentrations of insulin during late lactation but apparently had little effect during early lactation.

Animals↗
PubMed1996

Morphological study of age-related changes in Fischer rat lens.

The authors conducted a morphological investigation of age-related changes in the lens of male Fischer rats at 6, 12, 18 and 24 months of age. At 6 months, there were no abnormalities of particular note other than slight swelling of the subcapsular fibers. Moreover, other than a slight decrease in the density of epithelial cells and slightly more extensive fiber swelling, there were no remarkable changes seen in the lens at 12 months. At 18 months of age, posterior invasion by the processes of the cortical lens fibers toward the lens capsule and slight swelling of the anterior cortical fibers were seen in addition to the above-mentioned changes. By 24 months of age, these changes had become more noticeable, with further reduction in the density of epithelial cells, swelling and degeneration of both anterior and posterior fibers and extension of the thin processes of the equatorial fibers toward the capsule. However, the bow configuration at the equator appeared almost normal. These findings indicate that the age-related changes in the Fischer rat lens occurred in the epithelial cells and superficial layer of the cortical fibers, subsequently leading to the loss of clarity in the lens.

Aging↗
PubMed1995

Nonrandom distribution of sister chromatid exchanges in the chromosomes of three mammalian species.

The frequency and distribution of mitomycin C (MMC)-induced sister chromatid exchanges (SCEs) were investigated in the fibroblast chromosomes of three mammalian species, Microtus montebelli, Apodemus argenteus and Chimarrogale himalayica, by the fluorescence-plus-Giemsa (FPG) and C-band staining methods, paying special attention to the large C-band area (C-block)-carrying and/or nucleolus organizer region (NOR)-carrying chromosomes. The junctions of heterochromatin and euchromatin (HE-junctions) and NORs were found to be "hot spots" of SCEs in all the species examined: their SCE frequencies were 35.3% and 24.2% in the HE-junction of the X chromosomes of M. montebelli and A. argenteus, and 16.7% and 17.8% in the NORs of the No. 1 chromosomes of M. montebelli and C. himalayica, respectively. In M. montebelli and A. argenteus the SCE frequency was apparently lower in the C-block region than in the euchromatic one, when compared with each other based on equal length, while in C. himalayica no such marked difference in the SCE frequency was found between these two regions of the chromosome. These findings may indicate that occurrence of SCEs is significantly suppressed in the C-block region of M. montebelli and A. argenteus, but not in that of C. himalayica. In addition, the C-blocks of the No. 1 homologue of C. himalayica showed a highly varied individual-to-individual heteromorphism in length. The biological implication of SCEs was discussed in connection with the generation of heteromorphism.

Animals↗
PubMed1995

[The oxidative stress in the cataract formation].

The lens of the eye is an avascular tissue surrounded by fluids such as the aqueous humor and vitreous body, with one side facing toward the outside of the body. We investigated peroxidative reactions occurring in cataractous lenses, examining changes within the lens tissues as well as in the surrounding environment. 1. Peroxidative reactions in lenses. 1) Aging and peroxidative reactions. The activity of superoxide dismutase (SOD) began to decrease in the lenses of rats at six months of age. Moreover, the level of lipid peroxide increased significantly in the lenses of rats at 24 months of age. Lipoproteins became increasingly oxidized with age. The levels of Na+, K+, and Ca++, ions that are important to the maintenance of membrane function, also varied significantly with age. In the lenses of six-month-old Senescence Accelerated Mice (SAM), there was a marked decrease in the ability of scavenge active oxygen and a marked increase in the amount of lipid peroxide. In human lenses, the level of autofluorescence increased as the lens fiber structure changed with age. 2) Generation of free radicals inside the lens. We verified that HO. and ascorbic acid radicals were being generated inside cataractous lenses using electron spin resonance (ESR). 3) Changes in oxidation-related substances in cataractous lenses. Senile cataractous lenses and diabetic cataractous lenses were classified as four types, cortical, nuclear, posterior subcapsular, and mature. In cataractous lenses from all types of diabetic patients, the levels of glucose, glycated protein, and lipid peroxide were higher than in senile cataractous lenses. Among the four types of cataracts, the accumulation of peroxides was the greatest in the nuclear type both diabetic and senile cataractous lenses. 4) Transitional metals. Iron ions and copper ions existed in lens tissue. In particular, the subepithelial region of the lens stained strongly for copper ions. The increased level of copper ions in cataractous lenses is likely to be related to the increased peroxidation in this tissue. 5) Changes in membrane. Lowered levels of phospholipids and a higher degree of saturation of fatty acids were observed in senile cataractous lenses as compared with normal lenses. The increased saturation of fatty acids indicated that there was a damage to the membrane structure due to peroxidative reactions. The receptors for low density lipoprotein (LDL) were shown to exist on the epithelium of normal lenses. Acetyl-LDL, a denatured lipoprotein was incorporated into senile cataractous lenses but not into normal lenses, suggesting that the barrier function of the membrane deteriorates in cataractous lenses. Moreover, in diabetic cataractous lenses, the levels of very low density lipoprotein (VLDL) and LDL significantly increased. 2. Change in the environment surrounding the lens and peroxidative reactions. 1) Changes in the levels of oxidation-related substances in blood, aqueous humor, and vitreous body from diabetic patients: all had decreased levels of reduced glutathione and superoxide scavenging activity, and increased levels of lipid peroxide and glycated protein. This may have been due to a reduction in the anti-oxidative potential in the environment surrounding the lens due to the enhanced glycation. Changes in the level of oxidation related substances in the vitreous body in particular, will likely have a significant impact on the lens. 2) Changes in lenses as the surrounding environment deteriorates. Human lenses were cultured for three weeks under conditions similar to those found in vivo utilizing the culture system that we had originally designed and constructed. When protective activity against peroxidation was reduced, the amount of lipid peroxide increased significantly. In the presence of high levels of glucose, the levels of lipid peroxide increased and the amount and activity of SOD decreased. 3. Effects of changes in the external environment on peroxidative reactions.

Aged↗