Biomedical subjects

M Itoi

Publications and source records attributed to M Itoi.

At least 19 recordsLinked to original sources

PubMed2001

Two distinct steps of immigration of hematopoietic progenitors into the early thymus anlage.

Thymic epithelial cells, which create a three-dimensionally organized meshwork structure peculiar to the thymus, develop from simple epithelia of the third pharyngeal pouch and cleft during organogenesis. We comparatively investigated the thymus anlages of normal and nude mice by immunohistochemical analysis with regard to epithelial organization and distribution of hematopoietic progenitor cells at early stages of organogenesis. Our results show that development of the mouse thymus anlage at early stages can be subdivided into at least two stages by the differences in epithelial organization, i.e. stratified epithelial stage on embryonic day (Ed) 11 and clustered epithelial stage on Ed12. At the former stage, hematopoietic progenitor cells are accumulated in the mesenchymal layer of the thymus anlage, and at the latter stage progenitor cells enter the epithelial cluster and proliferate. In nude mice, hematopoietic progenitor cells are found in the mesenchymal layer on Ed11.5, but they are not observed among epithelial cells on Ed12, even though epithelial cells form a cluster structure. The present results suggest that aberrant development of the nude mouse thymus anlage occurs at the clustered epithelial stage and that epithelial cells of the nude anlage lack the ability to induce the entrance of hematopoietic progenitor cells into the epithelial cluster.

Animals↗

PubMed2001

Sequence analysis of candidate genes for common susceptibility to type 1 and type 2 diabetes in mice.

Although type 1 and type 2 diabetes are regarded as clinically distinct diseases, several lines of evidence have suggested common genetic factors between the two types of diabetes. The non-obese diabetic (NOD) mouse, an animal model of type 1 diabetes, and the Nagoya-Shibata-Yasuda (NSY) mouse, a model of type 2 diabetes, are derived from the same outbred colony, Jcl:HCR, suggesting a shared susceptibility between the two types of diabetes in mice. Genetic as well as functional studies have supported the possibility that Tcf2, which encodes the transcription factor, hepatocyte nuclear factor 1beta (HNF-1beta), is a candidate gene for the common susceptibility between NSY and NOD mice. Txn, encoding thioredoxin which is a redox (reduction/oxidation)-active protein, is also a positional and functional candidate for a common susceptibility gene. To investigate whether either of these two genes is a common susceptibility gene, the coding nucleotide sequences of these two genes were compared among the NSY, NOD and control C3H strains. The coding sequence of Tcf2 of the NOD mouse was identical to that of the C3H mouse, but was different from that of the NSY mouse. The coding sequence of Txn was identical in the three strains. These data suggest that neither of the two genes is a common susceptiblity gene between type 1 and type 2 diabetes in mice.

Animals↗

PubMed1999

Thymic microenvironments, 3-D versus 2-D?

Lympho-stromal interactions in the thymus crucially de- termine the fate of developing T cells. Epithelial cells, inter- digitating reticular cells, macrophages and fibroblasts all play a role in the shaping of the T cell repertoire. Recently published evidence shows that lympho-stromal interaction acts bi-directional. Developing T cell themselves, at different stages of differentiation, control the microarchitecture of thymic microenvironments, a phenomenon designated as 'crosstalk'. This paper reviews experiments showing that developing T cells crosstalk to different thymic epithelial cells in a stepwise fashion. In this way, correctly organized thymic microenvironments guarantee normal thymopoiesis.

Animals↗

PubMed1998

Inductive role of fibroblastic cell lines in development of the mouse thymus anlage in organ culture.

Previously, we have shown that embryonic day 12 thymus anlage cultured alone cannot develop into the mature organ but degenerates. In the present study, we investigated the cause of this insufficient organogenesis of embryonic day 12 thymus anlage in organ culture. We cocultured embryonic day 12 thymus anlages with various cell lines as pellets formed by centrifugation. In coculture with fibroblastic cell lines, but not with thymic epithelial cell lines, embryonic day 12 thymus anlages developed to support full T cell differentiation, and expressed mature stromal cell markers, Ia and Kb. By pellet culture of thymus anlages and fibroblastic cell lines transfected with a beta-galactosidase expression vector, we analyzed the distribution of added fibroblastic cells in pellets. The added fibroblastic cells constituted neither thymic capsule nor septa but disappeared after about 2 weeks in culture. Moreover, immunohistochemical studies indicated that added fibroblastic cells were adjacent to mesenchymal cells of thymus anlage. Our results strongly suggest that added fibroblastic cells support the development of the thymus anlage through interaction with its mesenchymal cells.

3T3 Cells↗

PubMed1996

Can the computerized physical examination differentiate normal subjects from abnormal subjects with benign mechanical low back pain?

Inconsistencies among physicians in the evaluation of benign low back conditions make standardization desirable. A computerized physical examination device was used to evaluate low back pain patients and compare their results with a normative database obtained from a selection of healthy subjects. A high-resolution motion analysis system tracked the movement of skin markers placed on the midline and pelvis. Surface electromyography electrodes placed above L(5) collected data from multifidus. From the kinematics of skin markers during flexion extension with lifts up to 32 kg, and lateral bending with lifts up to 4.6 kg, the following parameters were estimated: lumbosacral angle and elongation, contribution of each lumbar segment to the lordosis reduction, relative pelvic/spine motion and trunk velocity. First, the average normal value for each estimated parameter was determined using 40 normal subjects. For each subject, the difference between his parameter and the normal was processed by an expert system generating a normality index varying from zero (perfect abnormal) to one (perfect normal). To develop the expert system's rules, a preliminary group of 20 very abnormal subjects were used, such that the normality index separated them from the normals. For validation, a set of 29 WCB sprain patients and another set of 42 discogram positive were selected. Each subject was tested and his computerized normality index calculated without any clinicians' input. The computerized normality index was compared with the clinicians' evaluation which was taken to be the gold standard. The Receiver Operating Characteristic technique was used to quantify the discrepancies. Results show that the expert system can detect clinically abnormal subjects with accuracy (sensitivity 83-91% and specificity >/=90%) while providing quantitative information on workers' functional capacities.

Journal Article↗

PubMed1996

Corneal incisions utilizing the 1,053-nm picosecond Nd:YLF ophthalmic laser.

We evaluated the precision and predictability of a 1,053-nm picosecond Nd:YLF ophthalmic laser with various combinations of computer-controlled parameters. We utilized epithelium-free corneal-sclera preparations from NZW rabbits, and the 1,053-nm Nd:YLF laser (Intelligent Surgical Lasers, San Diego, CA, U.S.A.). X-line and line patterns were utilized to make linear corneal incisions. Three parameters (layer size, crossing width, and energy level) were evaluated. One parameter was changed for a total of 120 combinations of computer-controlled parameters. Three incisions were performed for each combination. Although the intended depths of the incisions were constant (300 mu m), the actual depths of the incisions varied with the change of parameters. Increasing layer size decreased the depth of incisions, and increasing crossing width or energy level increased the depth of incisions. Only three of 120 combinations of parameters achieved depths near 300 mu m. Within the same combination of parameters, the depth of the corneal incisions varied. Debris of ablated stromal tissue was observed at the border and partially occupying the incision. Most of the incisions were "funnel"-shaped with the distal treatment zone having a "zigzag" or irregular border. Further improvements are necessary to use this laser system for corneal transverse incisions.

Animals↗

PubMed1995

Limited development capacity of the earliest embryonic murine thymus.

Previous studies have demonstrated that murine thymus separates from the pharynx during 11.5-12 days of gestation, and that the proliferation of thymic cells starts at this age. We characterized embryonic day 12 thymus in terms of the surface phenotype of the thymus cells, the function of the lobe in supporting T cell development in organ culture, and the precursor activity of the thymus cells in a mixed culture with deoxyguanosine-treated lobes. The phenotype of the major population of embryonic day 12 thymus cells was HSA+, CD44+, c-kit+, Thy-1-, CD25-, CD4-, CD8-, TcR-, and Sca-1-. In organ culture of embryonic day 12 thymus lobes, most of the lobes did not develop well and failed to generate CD4+CD8+, CD4+CD8-, or CD4-CD8+ cells, even when embryonic day 14 thymus cells were added. However, thymus cells on embryonic day 12 contained T cell precursors that developed into mature T cells in co-culture with deoxyguanosine-treated fetal thymic lobes. The majority of the stromal cells in deoxyguanosine-treated embryonic day 14 thymus lobes expressed the surface molecules I-A and H-2D, whereas these cells in embryonic day 12 thymus lobes were negative for these surface molecules. Thus, our findings suggest that the embryonic day 12 thymus lobe contains T cell precursors, but that the undeveloped thymic stromal cells are insufficient to support full T cell development.

Animals↗

PubMed1995

Effect of sodium hyaluronate ophthalmic solution on peripheral staining of rigid contact lens wearers.

We evaluated the efficacy of sodium hyaluronate ophthalmic solutions on 3 and 9 o'clock staining with rigid contact lens wearers in a double masked multicenter study involving four institutions and 43 patients. Both sodium hyaluronate (0.1%) and control ophthalmic solutions (artificial tears) without preservative were used. Patients were randomly divided into two groups. The test group received sodium hyaluronate ophthalmic solution, and the control group received artificial tears as a control ophthalmic solution. The agents were instilled six times per day for 2 weeks while patients wore contact lenses. Although subjective symptoms improved similarly in the two groups, slit lamp observation, corneal staining, and anterior segment photography demonstrated improved results in eyes having received sodium hyaluronate ophthalmic solutions. We conclude that sodium hyaluronate ophthalmic solution is effective and safe for treating 3 and 9 o'clock staining in rigid contact lens wearers.

Administration, Topical↗

PubMed1993

Glutathione isopropyl ester (YM737) inhibits the progression of X-ray-induced cataract in rats.

The effect of glutathione (GSH) isopropyl ester on the progression of X-ray-induced cataract was investigated in rats. Intraperitoneal administration of 20 mg/kg GSH isopropyl ester, three times weekly, 1 day after a single irradiation dose delayed the progression of X-ray-induced cataracts significantly. The amount of non-protein SH groups and the Na+/K+ ratio in the lenses of drug-treated rats were maintained at the normal levels even 27 weeks after irradiation. Posttreatment with the drug resulted in a significantly lower level of malondialdehyde in the irradiated lenses than in the nontreated lenses. When 500 mg/kg GSH-isopropyl ester was administered by i.p. injection to normal rats, the GSH-ester was detected in plasma and aqueous humor after 15 min. In the lenses of the GSH-isopropyl ester-injected rats, the GSH level was 120% of that in the non-treated rats after 4 h, suggesting that GSH-isopropyl ester is transported from the aqueous humor to the lens and there converted to GSH after about 4 h. Our observations lead us to conclude that the delay of X-ray-induced lens opacity progression is due to maintenance of normal lenticular GSH levels achieved by post-irradiation administration of GSH-isopropyl ester. However, continuous administration of 100 mg/kg after irradiation had no effect on the progression of cataracts induced by X-rays.

Animals↗

PubMed1993

Case-control study of senile cataract in Japan: a preliminary report.

A hospital-based case-control study of senile cataract was conducted in Japan from 1988 to 1990. Two hundred and twelve patients with senile cataract and 212 control subjects with the same age-sex distribution were interviewed and given an ophthalmological examination. Both groups were randomly selected outpatients from 9 hospitals. Associations between senile cataract and four groups of variables, factors regarded as risks, life style habits, general aging indices or other factors were analyzed, and the data was subjected to statistical analysis. An increased risk of cataract was found in males who were presently spending 7 hours or more outside daily (Odds ratio = 5.07) and in females with 4 or fewer remaining teeth (Odds ratio = 2.03). The findings from this study suggest that there may be a sex-related host sensitivity or life style which is predisposing to the development of senile cataract.

Adult↗

PubMed1993

Distribution of epidermal growth factor receptors in rabbit lens epithelial cells.

PURPOSE: This study examined the growth-promoting effect of epidermal growth factor (EGF) on rabbit lens epithelial cells and the distribution of EGF receptors in these cells. METHODS: Rabbit lens epithelial cells were cultured in TC-199 medium containing 0.5% fetal bovine serum and EGF for 1 to 5 days, and the growth-promoting effects of EGF were calculated with absorbance of methylene blue staining method. EGF receptors in the cells were analyzed by Scatchard plots using 125I-EGF in serum-free culture. RESULTS: EGF, which enhanced the cell growth in a dose-dependent manner, was stimulatory at 0.1-100 ng/ml and maximal (328.2%) with 10 ng/ml on day 5. The cells had two different affinity receptors. The number and the dissociation constant of the low affinity receptors were 5.81 x 10(4)/cell and 1.488 nM, respectively, and those of the high affinity receptors were 1.53 x 10(4)/cell and 0.159 nM, respectively. CONCLUSION: EGF may contribute to the development of living lenses.

Animals↗

PubMed1992

Distribution of epidermal growth factor (EGF) receptors in rabbit corneal epithelial cells, keratocytes and endothelial cells, and the changes induced by transforming growth factor-beta 1.

Three kinds of rabbit corneal cells (epithelial cells, keratocytes and endothelial cells) were cultured, and the growth promoting effects of epidermal growth factor (EGF) were examined in these cells. It was found that the sensitivity of the epithelial cells to EGF was the highest, that of the endothelial cells was a little lower, and that of the keratocytes was the lowest. Transforming growth factor-beta 1 (TGF-beta 1) did not influence growth of the three kinds of corneal cells. It was found that TGF-beta 1 enhanced the growth promoting effect of EGF in the keratocytes, but not in the epithelial and endothelial cells. EGF receptors in the corneal cells were labelled with [125I]EGF and analysed by Scatchard plot. In the epithelial and endothelial cells, both high and low affinity receptors were found, while the keratocytes had only low affinity receptor. In the epithelial cells, the number and the association constant of the high affinity receptors were, respectively, 2.79 x 10(4) per cell and 0.034 nM, and those of the low affinity receptors were, respectively, 13.4 x 10(4) per cell and 0.700 nM. In the endothelial cells, the number and the association constant of the high affinity receptors were 1.27 x 10(4) per cell and 0.086 nM, respectively, and those of the low affinity receptors were 8.91 x 10(4) per cell and 1.536 nM. In the keratocytes, the number of receptors and the association constant were 9.49 x 10(4) per cell and 1.535 nM, respectively. The corneal cells were treated with TGF-beta 1 for 24 hr and its influence on EGF receptors was examined. The results showed that TGF-beta 1 induced the high affinity receptors in the keratocytes, although TGF-beta 1 did not influence EGF receptors in the epithelial and endothelial cells. The number of high affinity receptors in keratocytes treated with TGF-beta 1 was 1.02 x 10(4) per cell and the association constant was 0.171 nM (this was approximately tenfold higher than that of the receptor of keratocytes not treated with TGF-beta 1).

Animals↗

PubMed1992

Changes of glutathione and taurine concentrations in lenses of rat eyes induced by galactose-cataract formation or ageing.

Sulphur-containing compounds in the lens were studied in relation to galactose cataract formation. Female Wistar rats were fed a 35% galactose diet and the changes in lens sulphur concentration and its distribution on a gel filtration column were compared with age-related changes. Concentration of sulphur in the whole lens decreased with time. A low constant level was attained on the fifth day of the galactose diet. A decrease of sulphur concentration in the soluble fraction of the lens paralleled that of the whole lens which was correlated with the decrease of glutathione and taurine concentrations on a gel filtration column by high-performance liquid chromatography-inductively coupled argon plasma atomic emission spectrometry (HPLC-ICP). Concentration of magnesium in the lens decreased after the fifth day, while the ratio of sodium to potassium increased. These changes in sulphur-containing compounds and metals were observed prior to the onset of cataract formation.

Aging↗

PubMed1992

Effects of 2-mercaptopropionylglycine on the development of X-ray-induced cataract in rats.

The effect of 2-mercaptopropionylglycine on the development of cataract induced by a single dose of X-ray (10 Gy) was investigated in rats. Intraperitoneal injection of 20 mg/kg, three times weekly starting 1 day after irradiation delayed the development of X-ray-induced cataracts significantly. The amounts of non-protein SH groups, malondialdehyde and the Na+/K+ ratio, in the lenses of rats post-treated with the drug were significantly maintained at normal levels even at 27 weeks after irradiation. On the other hand, a single administration of 250 mg/kg of the compound, 30 min prior to irradiation had no effect on cataract progression induced by X-ray.

Animals↗

PubMed1991

Ultrastructural observations of typical gap junctions in human foetal lens nucleus.

The ultrastructure of gap junctions throughout the human foetal lens was observed. By freeze-fracture analysis, we observed numerous gap junctions in both lens cortex and lens nucleus. Comparison between lens cortex and lens nucleus showed that the gap junctions of lens nucleus are characterized by extreme mosaics of closely apposed P- and E-faces in junctional areas, though no significant difference in the area of gap junctions was observed between lens cortex and lens nucleus. In addition, some morphological variations, such as the smooth domains without particles or pits in junctional areas and the reticulated figures of gap junctions, were observed only in the lens nucleus. We also observed by thin-section electron microscopy that cell membranes of human foetal lens nucleus, as observed in the lens cortex, are mainly composed of continuous lipid bilayer and junctional structures. We concluded that characteristic morphology of lens gap junctions, as observed in the cortex of human foetal lens, is mostly preserved in the human foetal lens nucleus, although some depth-dependent alterations were also observed.

Fetus↗

PubMed1990

Classification system for cataracts. Application by the Japanese Cooperative Cataract Epidemiology Study Group.

A cataract classification and grading system for the main purpose of cataract epidemiological studies is proposed by the Japanese Cooperative Cataract Epidemiology Study Group. Cataractous types are classified principally into cortical, nuclear and subcapsular opacities. Stages of cataract advancement are classified into grade I (early stage), grade II (moderate stage) and grade III (advanced stage). Regarding cortical opacities an opacified area obtained from red-reflex images is utilized for grading judgment. Nuclear opacity grading is based on the intensity of scattering at the nucleus. Grading of subcapsular opacities is judged from their extension in the three different pupillary areas. To help grading judgments, standard pictures of cortical and nuclear cataracts are provided. Gradings of lens coloration are divided into pale yellow (grade I), yellow (II), brownish yellow (III) and brown including reddish and black brown (IV). A recording chart is also provided.

Adult↗

PubMed1990

Spreading of cultured corneal epithelial cells on fibronectin and other extracellular matrices.

Previous investigations demonstrated that fibronectin is an essential adhesive glycoprotein for the corneal epithelial cells. Fibronectin mediates attachment and spreading of the corneal epithelial cells. However, it seems to be important to know the changes in cellular receptor activity in order to understand the interactions of corneal epithelial cells and underlying extracellular matrix. In this investigation, we studied the effects of various culture times and conditions on the receptor activity of rabbit corneal epithelial cells for fibronectin. The cultured cells were placed on tissue culture plates that were coated with various concentrations of four extracellular matrices: fibronectin, laminin and collagen types I and IV. Freshly isolated corneal epithelial cells without culture did not spread on fibronectin and laminin; they spread only on collagen types I and IV. When the epithelial cells were cultured for 12 h or more, they spread on fibronectin. However, the spreading of the cells on collagen types I and IV was the same regardless of the culture period (up to 20 h). Only a small number of epithelial cells spread on laminin at the highest concentration examined after culture for 12 h or more. Thus, the corneal epithelial cells responded differently to fibronectin, collagen types I and IV, and laminin. Perhaps the receptor for fibronectin appears when epithelial cells are cultured, but the receptor(s) for collagen types I and IV are always present on the cell surface of corneal epithelial cells.

Animals↗

PubMed1989

Changes in lens proteins induced at the early stage of cataractogenesis in cac (Nakano) mice.

Changes in lens proteins induced at the early stages of cataractogenesis in cac (Nakano) mice were investigated by two-dimensional gel electrophoresis (2D-PAGE). The 2D-PAGE profile of lens proteins in 21-day-old cac mice differed from that in 27-day-old normal mice, even though the appearance of 'pin-head' nuclear opacity (26-day-old) had not yet been observed in the lenses. Especially noticeable were great differences in the polypeptides associated with the alpha- and beta- crystallin subfractions, the appearances of which corresponded to an increase in a ratio of the amounts of Na+ to that of K+ in the lenses of defective mice. No dramatic decrease in the gamma-crystallin fraction was observed until the mature cataract stage.

Animals↗