Biomedical subjects

G Eguchi

Publications and source records attributed to G Eguchi.

At least 19 recordsLinked to original sources

PubMed1992

Tissue-specific response of estrogen receptor gene expression to estrogen in chick.

We have developed a sensitive assay system by RT (reverse transcription)-PCR(polymerase chain reaction) to detect the low level of chicken estrogen receptor (cER) transcript. Using this system, the differential expression of cER gene in chick tissues was observed. Moreover, we found that the oviduct cER transcript levels in chick was not affected, albeit the remarkable growth of this tissue, by exogenous estrogen. In contrast, estrogen enhanced the hepatic cER transcript level several folds. Thus, the present study clearly showed a novel tissue-specific response of cER gene expression to estrogen in chick.

Animals↗

PubMed1992

Crystallin gene expression in the process of lentoidogenesis in cultures of chicken lens epithelial cells.

One alpha B- and three different beta-crystallin cDNA clones were isolated from a chicken lens cDNA library by using anti-crystallin antibodies. The sequence of alpha B-crystallin cDNA showed more than 70% homology with exons of alpha B-crystallin genes of the human and hamster. Two beta-crystallin cDNAs showed almost identical sequences with previously reported chicken beta B1- and beta A3/A1-crystallin genes. The remainder showed 80% homology of sequence with bovine beta B2-crystalline cDNA. Using these newly cloned cDNAs, in addition to cDNAs of alpha A- and delta-crystallin, we examined the expression pattern of these crystallins in the process of lentoidogenesis of cultured lens epithelial cells of the chicken. All crystallins except beta-crystallins were expressed through the period of cell culture, but three beta-crystallins were expressed only after the confluent stage. These results suggest that: (1) alpha A-, alpha B- and delta-crystallin cDNAs can be used to detect differentiation of the lens epithelial cell; and (2) beta-crystallin cDNAs are superior in the detection of chicken lens fibre differentiation in vitro to delta-crystallin cDNA, which is ectopically expressed by various non-lenticular tissues.

Amino Acid Sequence↗

PubMed1992

Transdifferentiation of chicken retinal pigmented epithelial cells in serum-free culture.

A serum-free culture of chicken retinal pigmented epithelial cells has been established in order to analyse how cell-substrate interactions or environmental factors affect the process of transdifferentiation into lens cells from pigmented epithelial cells. The serum-free culture medium for chicken pigmented epithelial cells was Eagle's minimum essential medium, supplemented with chicken transferrin, soybean trypsin inhibitor and bovine insulin. Pigmented epithelial cells were able to survive and grow in the medium for longer than 2 weeks. Collagen did not promote initial cell attachment, but this material effectively supports pigmented epithelial cells to organize monolayer structure characteristics to pigmented epithelium in situ in comparison with the plastic substrate of culture dishes. The process of lens transdifferentiation of chicken pigmented epithelial cells in serum-free conditions was also enhanced with the aid of phenylthiourea and testicular hyaluronidase, which had already been known to promote the transdifferentiation of pigmented epithelial cells in the serum-supplemented condition. Typical lentoid bodies were developed after about 2 weeks of serum-free culture. Thus, we can clearly demonstrate that the chicken embryonic pigmented epithelial cells do not always require a full set of serum factors for their transdifferentiation to lens cells in vitro.

Animals↗

PubMed1992

Evaluation of a high-velocity flame-spraying technique for hydroxyapatite.

Titanium alloy sprayed with hydroxyapatite (HA) was developed by a high-velocity flame-spraying technique (HVFST). Biocompatible responses of bony tissues to high-velocity flame-sprayed HA (HVFS-HA) implanted into tibias of adult male rabbits was investigated 4 and 18 months after implantation by light and electron microscopy. Both light and electron microscope features in histological sections showed that inflammatory responses of tissues in situ were completely cleared and the interface between the bone and the implant was filled with newly formed bony substrate. This suggests that the HVFS-HA was sufficiently biocompatible to be adapted to the bone in situ.

Alloys↗

PubMed1992

Isolation and characterization of a chicken tyrosinase cDNA.

Complementary DNA clones coding for chicken tyrosinase were isolated from retinal pigmented epithelium of chicken embryo. Sequence analysis shows that one of the cDNA clones consisting of 1,997 nucleotides has an open reading frame coding for 529 amino acids. The deduced protein has nine N-glycosylation sites and a transmembrane region. A sequence comparison of the deduced chicken tyrosinase with the mouse and human homologues revealed that amino acid sequences are conserved for the entire polypeptides. Seventy-two percent and 73% of amino acids in the chicken sequence are identical to that of the mouse and human tyrosinases, respectively. Histidines neighboring the postulated copper-binding sites and the cysteines are well conserved. RNA blotting analysis showed that a major transcript of 2.5 kb is detected in retinal pigmented epithelium of a 9-day-old chicken embryo.

Amino Acid Sequence↗

PubMed1992

Analysis of a unique molecule responsible for regeneration and stabilization of differentiated state of tissue cells.

In Wolffian regeneration in the newt, a functional lens can be regenerated through cellular transdifferentiation of the pigmented epithelium of the mid-dorsal marginal iris. A novel monoclonal antibody, 2NI-36 mAb, generated in our laboratory has been utilized as a highly useful probe to study newt lens regeneration. The antigen molecule against this 2NI-36 mAb (2NI-36) became temporarily undetectable only at the site of lens regeneration. Moreover, the ventral iris pieces expressed the ability to differentiate a lens when pretreated with this monoclonal antibody and implanted in lentectomized eyes (Eguchi, Cell Differ. Dev. 25, Suppl., 1988). We have investigated the distribution of 2NI-36 in newt tissues. 2NI-36 was not specific to iris pigmented epithelium and distributed in many different kinds of mesodermal tissues, including dermis, blood vessel, mesonephros and so forth. 2NI-36 was also detected in either cell surface or intercellular spaces of cultured pigmented epithelial cells when they organized an epithelial cell sheet. Western blot analysis showed that 2NI-36 had the molecular weight of 50-200kD and was completely digested by trypsin, suggesting that 2NI-36 was a glycoprotein with many carbohydrate chains. It was also revealed by Western blot analysis that all the tissues in which 2NI-36 could be detected expressed this molecule similar to that in the iris epithelium. We expect that 2NI-36 is a glycoprotein expressed by various newt tissues and is functional to stabilize the differentiated state of each tissue cell in the same way as observed in the iris pigmented epithelial cells.

Animals↗

PubMed1992

Expression and distribution of regeneration-responsive molecule during normal development of the newt, Cynops pyrrhogaster.

We have investigated the expression and distribution of the regeneration-responsive molecule, 2NI-36, the loss of which is responsible for initiation of dedifferentiation of dorsal marginal iris pigmented epithelial cells to regenerate a lens. In the process of the normal development of the newt, the expression of 2NI-36 could not be detected in embryos at the early developmental stages, i.e., cleavages, gastrulation and neurulation, nor through later developmental stages to tail-bud, even though organogenesis was occurring. 2NI-36 was not detectable in any tissues until embryos reached developmental stage 40 (before hatching). In hatched larvae around developmental stage 46, strong expression of 2NI-36 was observed in several tissues including the vascular endothelium, the pigmented epithelium and the inner layer of skin epidermis. Moreover, 2NI-36 was present on the cell surface of these tissue cells. In conclusion, when the embryos hatch out to become swimming larvae that can feed by themselves, 2NI-36 begins to be expressed in some kinds of differentiated tissues. These results suggest that the function of 2NI-36 might be related to the completion of morphogenesis in development and also to the stabilization of the differentiated state of newly formed tissue cells.

Animals↗

PubMed1991

Ultrastructural and immunocytochemical analysis of the circumferential microfilament bundle in avian retinal pigmented epithelial cells in vitro.

The dedifferentiated phenotype of pigmented epithelial cells in vitro is bipotential and is effected by environmental alterations mediated by the cell surface and associated cytoskeleton. We have begun an investigation into the role that contractile microfilaments play in maintaining cell contact and cell shape in retinal pigmented epithelial cells in vitro. In this paper, we report a structural analysis of the intersection of the circumferential microfilament bundle with the cell membrane of cultured pigmented epithelial cells from chick retina. Techniques of electron microscopy, including freeze-fracturing and deep-etching, reveal that microfilaments of this bundle associate with a junctional complex in the apical cell compartment and with membrane domains which are not components of the junction. Microfilaments link with the cell membrane either at their termini or along the membrane-apposed surface of the circumferential bundle. Furthermore, we report the immunocytochemical localization of filamin (a high molecular weight actin-binding protein, which forms fiber bundles and sheet-like structures when bound with F-actin in solution) in the circumferential/microfilament bundle.

Actin Cytoskeleton↗

PubMed1991

Isolation of cDNA for a Xenopus sperm-specific basic nuclear protein (SP4) and evidence for expression of SP4 mRNA in primary spermatocytes.

A cDNA library was prepared in lambda gt 11 from poly(A)+ mRNA isolated from a pure population of Xenopus round spermatids and screened with an antibody against SP3-5 (sperm-specific proteins) of Xenopus sperm. Positive clones were sequenced and an arginine-rich clone, designated pXSP531, was obtained. The 473-nucleotide sequence of pXSP531 contained an open reading frame of 237 nucleotides which was preceded by a 5' untranslated region of 67 nucleotides. The 3' untranslated region contained 149 nucleotides, including a consensus polyadenylation signal (AAATAAAA). Twenty nucleotides of a poly(A) tail was contained in the pXSP531. SP3-5 were separated from each other by reverse-phase chromatography and sequenced. The amino acid sequence of the peptide fragments which were obtained by digestion of SP4 with V8 protease and separated by reverse-phase chromatography was identical to the sequence of the N-terminal 43 and C-terminal 15 amino acids deduced from the nucleotide sequence of pXSP531. This result demonstrates that pXSP531 encodes SP4. Northern hybridization of RNA extracted from primary spermatocytes and round spermatids on Days 0 and 6 with SP4 cDNA probe (pXSP531) showed that SP4 mRNA is present both in primary spermatocytes and in round spermatids as is protamine mRNA in the rainbow trout. The size of the SP4 mRNA in round spermatids on Day 0 was longer by 60 nucleotides compared to that in primary spermatocytes and that in spermatids on Day 6 was shorter by 30 nucleotides compared to that on Day 0. These size differences were due to differences in the length of the poly(A) tracts because digestion of poly(A) with ribonuclease H resulted in the shortening of mRNA to the same size for three stages.

Amino Acid Sequence↗

PubMed1991

Study of crystallin expression in human lens epithelial cells during differentiation in culture and in non-lenticular tissues.

Crystallin expression in human lens epithelial cells in culture and a number of non-lenticular tissues was studied by the technique of immunoblotting using monoclonal antibodies. The expression of alpha A, beta 5 and beta 6 crystallins per unit number of cells increased with passage number while alpha B appeared to be constant Lentoid bodies derived from cultured human lens epithelial cells not only expressed gamma-crystallin and MP26 as previously demonstrated, but also produced alpha A, alpha B, beta 5 and beta 6 crystallins. In human non-lenticular tissues including ciliary body, vitreous body, neural retina, cultured retinal pigment epithelial cells and scleral fibroblasts, alpha B-crystallin was detected, but was undetectable in cornea and iris. Alpha A was present only in the lens. These studies demonstrate that HLE cells maintain the ability to synthesize crystallins through several passages. Following differentiation, they not only synthesize gamma-crystallin and MP26 but continue to express alpha- and beta-crystallins similar to differentiated lens fiber cells in vivo. Consistent with previous observations, the expression of alpha B-crystallin does not appear to be specific for the lens.

Cell Differentiation↗

PubMed1991

The A5 antigen, a candidate for the neuronal recognition molecule, has homologies to complement components and coagulation factors.

The A5 antigen is a neuronal cell surface protein of Xenopus presumed to be involved in the neuronal recognition between the optic nerve fibers and the visual centers. Analyses of cDNA clones revealed that the A5 antigen is a class I membrane protein containing two different internal repeats in the extracellular segment. The first repeat bears homology to domain III of complement components C1r and C1s, and the second repeat is homologous to the C1 and C2 domains of coagulation factors V and VIII. The mRNA for the A5 antigen was present in retinal ganglion cells and visual center neurons. Nonneuronal cells in the peripheral and central nervous systems did not express the mRNA for the A5 antigen.

Amino Acid Sequence↗

PubMed1991

Complete sequence and expression of a cDNA encoding a chicken 115-kDa melanosomal matrix protein.

A full-length cDNA clone encoding a 115-kDa melanosomal matrix protein (MMP115) was isolated from a cDNA library constructed from poly(A)+ RNA of the chicken pigmented epithelial cells. Sequence analysis showed that the cDNA encoded a polypeptide of 762 amino acids, including a hydrophobic signal peptide. There are no membrane-spanning regions, but there are five N-linked glycosylation signals. A cysteine- and histidine-rich domain is present near the C-terminus. A sequence of 24 amino acids is repeated three times in the polypeptide. A database search for homologies yielded no sequence similarities in other proteins. A plasmid containing the full-length cDNA was transferred into mouse cell lines by transfection. The transfected cells produced a protein that had the same size, 115 kDa, as the mature MMP115. When B16 mouse melanoma cells were transfected, the chicken MMP115 was expressed in the melanosomes. The presence of a specific sorting signal was suggested for localization of melanosomal proteins. Southern blot analysis has revealed that the homologues of the chicken MMP115 gene are found in many vertebrate genomes.

Amino Acid Sequence↗

PubMed1991

Multiple brain tumors of different cell types with an unruptured cerebral aneurysm--case report.

A rare case of coexistent Burkitt-type lymphoma and meningioma associated with an unruptured cerebral aneurysm is presented. A 49-year-old male complaining of headache and right hemiparesis was admitted to our hospital. Neuroradiological examination revealed a multinodular mass in the left frontal convexity and an unruptured cerebral aneurysm at the M1 portion of the left middle cerebral artery. He underwent an operation for tumor removal and aneurysm clipping. Histological examination revealed the tumor to be a typical meningotheliomatous meningioma without malignancy. However, a second operation was necessary for another tumor invading into the left frontal lobe, which proved to be a Burkitt-type lymphoma. The second tumor may have been resulted from irritative effect of the first tumor, but the aneurysm was considered purely coincidental.

Brain Neoplasms↗

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↗

PubMed1991

Embryonic expression of beta-actin-lacZ hybrid gene injected into the fertilized ovum of the domestic fowl.

An experiment was carried out to investigate the expression of cloned DNA injected into the germinal disc of the chick fertilized ovum. The beta-actin-lacZ hybrid gene, MiwZ, was injected, in the closed circular form, into the cytoplasm of the germinal disc at the single-cell stage. The embryos were cultured in vitro, then in recipient eggshells up to day 4 of incubation. The survival rate of the embryos at day 4 was 42% (55/130), and the rate of embryos expressing MiwZ was 64% (35/55). Twenty-two embryos expressed the MiwZ in both embryonic and extraembryonic tissues, while the remainder expressed the MiwZ in only extraembryonic tissues. Mosaic expression was observed in most of the embryos expressing MiwZ in embryonic tissues. Expression throughout all tissues of the embryo including blood cells occurred in one case. In this case, the injected DNA was assumed to have integrated at an earlier stage. The results indicate that it is now possible to investigate the promoter activities of introduced exogenous genes as well as the effect of introduced genes on embryogenesis in early chick embryos. This technique may also facilitate the production of transgenic chicks.

Actins↗

PubMed1990

Aortic endothelial cells synthesize a large chondroitin sulphate proteoglycan capable of binding to hyaluronate.

Confluent cultures of mouse aortic endothelial (END-D) were incubated with either [35S]methionine or 35SO4 2-, and the radiolabelled proteoglycans in media and cell layers were analysed for their hyaluronate-binding activity. The proteoglycan subfraction which bound to hyaluronate accounted for about 18% (media) and 10% (cell layers) of the total 35S radioactivity of each proteoglycan fraction. The bound proteoglycan molecules could be dissociated from the aggregates either by digestion with hyaluronate lyase or by treatment with hyaluronate decasaccharides. Digestion of [methionine-35S]proteoglycans with chondroitinase and/or heparitinase, followed by SDS/polyacrylamide-gel electrophoresis, indicated that the medium and cell layer contain at least three chondroitin sulphate proteoglycans, one dermatan sulphate proteoglycan, and two heparan sulphate proteoglycans which differ from one another in the size of core molecules. Among these, only the hydrodynamically large chondroitin sulphate species with an Mr 550,000 core molecule was shown to bind to hyaluronate. A very similar chondroitin sulphate proteoglycan capable of binding to hyaluronate was also found in cultures of calf pulmonary arterial endothelial cells (A.T.C.C. CCL 209). These observations, together with the known effects of hyaluronate on various cellular activities, suggest the existence of possible specialized functions of this proteoglycan subspecies in cellular processes characteristic of vascular development and diseases.

Aggrecans↗

PubMed1990

Partial amino acid sequence of the major intrinsic protein (MIP) of the chicken lens deduced from the nucleotide sequence of a cDNA clone.

A cDNA clone of the major intrinsic protein (MIP) of the chicken lens was isolated. This clone covers the C-terminal half of the coding region and 3'-untranslated region including a polyadenylation signal. Comparison with the bovine MIP cDNA sequence revealed that: (1) the amphilphilic transmembrane helix in bovine MIP is highly hydrophobic in chicken MIP, and is thus unlikely to offer a hydrophilic lining of the transmembrane pore, and (2) the possible calmodulin binding site is conserved especially at amino acid residues which are postulated to be important in its binding with calmodulin. Northern blotting revealed the presence of transcripts of different lengths, two of which correspond closely to the transcripts of bovine MIP.

Amino Acid Sequence↗

PubMed1990

[Massive traumatic hematoma localized in the basal ganglia: treatment by CT-guided stereotactic aspiration surgery].

A case of massive traumatic hematoma of the basal ganglia which was treated successfully by CT-guided stereotactic aspiration surgery, was reported. A 6-year-old boy was admitted 2 hours after a traffic accident. He had no neurological focal signs except for disturbance of consciousness on admission. CT scan revealed a massive hematoma in the right basal ganglia. His neurological status gradually deteriorated 6 hours after the trauma and the size of the hematoma increased on serial CT scan. Then, CT-guided stereotactic aspiration surgery was performed and about 15.5 ml of hematoma clot was successfully evacuated. He made an uneventful recovery from the operation and gradually improved. The final outcome was that he showed moderate disability at 3 months after the trauma. The possible mechanism of development of hematoma in this lesion, and indication of CT-guided stereotactic aspiration surgery were also discussed.

Basal Ganglia Diseases↗