Biomedical subjects

Y Imanishi

Publications and source records attributed to Y Imanishi.

At least 19 recordsLinked to original sources

PubMed1999

Analysis of the RAD54 gene on chromosome 1p as a potential tumor-suppressor gene in parathyroid adenomas.

Parathyroid adenomas causing primary hyperparathyroidism (pHPT) frequently exhibit allelic loss of DNA markers on the short arm of chromosome 1, indicating the presence of one or more tumor-suppressor genes on 1p. Since the development of pHPT is enhanced in individuals exposed to ionizing radiation to the neck, it could be anticipated that genes involved in DNA repair and recombination may be special targets for mutation in parathyroid tumorigenesis, whether irradiation-associated or not. RAD54 is a member of a family of genes involved in such functions, and RAD54 knockout mice show increased sensitivity to ionizing radiation. The localization of the RAD54 gene to 1p32 has therefore elevated it to a most compelling candidate parathyroid tumor-suppressor gene. Twelve parathyroid adenomas demonstrating allelic loss at chromosome 1p were selected from 55 parathyroid adenomas previously analyzed for loss of heterozygosity using polymorphic microsatellite markers. All 18 exons of the RAD54 gene were fully analyzed by automated sequencing for detection of point mutations or micro-deletions in each parathyroid adenoma. No mutational aberrations were detected in the RAD54 gene, strongly suggesting that complete somatic inactivation of RAD54 is infrequently, if ever, associated with the development of parathyroid adenomas. Whether genes controlling DNA repair and recombination are involved in parathyroid neoplasia remains to be determined.

Adenoma↗

PubMed1999

Three kinds of guanylate cyclase expressed in medaka photoreceptor cells in both retina and pineal organ.

Three kinds of cDNAs encoding the putative photoreceptor-specific guanylate cyclases (GCs), OlGC-R1, OlGC-R2, and OlGC-C, were isolated from a retinal cDNA library of the medaka, Oryzias latipes. The deduced amino acid sequences of OlGC-R1 and -C are closely related but slightly different from those of OlGC4 and OlGC5, respectively. In situ hybridization locates the mRNA of both OlGC-R1 and -R2 in rods, and OlGC-C mRNA is found in all four types of cone cells. It is likely that medaka rods and cones produce distinct GC subtypes and that two kinds of photoreceptor-specific GCs are coexpressed in rods. Also, hybridization signals are detected in the pineal organ, suggesting that OlGC-R1 and -C contribute also to phototransduction in pinealocytes.

Amino Acid Sequence↗

PubMed1999

Enzyme modification by polymers with solubilities that change in response to photoirradiation in organic media.

We have synthesized a hybrid subtilisin the solubility of which can be regulated by photoirradiation through coupling with a photoresponsive copolymer that carries spiropyran groups in its side chains. The copolymer was synthesized by polymerization of methacrylate, methacrylic acid, and spiropyran-carrying methacrylate. It was then covalently bonded to the amino groups of subtilisin Carlsberg via its carboxyl groups using a carbodiimide coupling agent. The hybrid subtilisin was perfectly soluble in toluene and efficiently catalyzed transesterification. After ultraviolet irradiation, the hybrid subtilisin precipitated and was easily and quantitatively recovered by centrifugation. Recovered hybrid subtilisin, resolubilized by visible light irradiation, retained its original transesterification activity even after several cycles of precipitation and solubilization.

Benzopyrans↗

PubMed1999

Relapsing polychondritis diagnosed by Tc-99m MDP bone scintigraphy.

PURPOSE: Relapsing polychondritis is a generalized recurring disease of cartilage that involves joints, trachea, bronchi, laryngeal cartilages, costal cartilages, and cartilages of the ear and nose. It is associated with autoimmune diseases, including Hashimoto disease in some cases. METHODS: The authors evaluated a 29-year-old man with relapsing polychondritis who had symptoms and signs of a common cold for 2 months and anterior chest pain near the sternum for 1 month. RESULTS: After the diagnosis, the authors found that the patient had a history of thyroid therapy for hyperthyroidism 15 years before. Tc-99m MDP bone scintigraphy performed to evaluate anterior chest pain showed diffusely increased accumulation of radioactivity in all costocartilages and sternoclavicular joints. Based on that information, relapsing polychondritis was diagnosed. Ga-67 citrate scintigraphy was preformed to determine the optimum biopsy site of the cartilage. The diagnosis was histologically supported by the results of the open biopsy. CONCLUSIONS: In this case, Tc-99m MDP bone scintigraphy was useful for diagnosing relapsing polychondritis, and Ga-67 citrate scintigraphy was helpful in determining the biopsy site.

Adult↗

PubMed1999

[Statistical analysis of localized non-Hodgkin's lymphomas of the head and neck--multivariate analysis of prognostic factors and evaluation of therapeutic modalities].

Prognostic factors and treatment outcome of 48 patients with Stage I (29) or II (19) non-Hodgkin's lymphoma of the head and neck were analyzed retrospectively. There were 26 males and 22 females, aged from 15 to 89 years old, with an average age of 57. The primary lesion was located in Waldeyer's ring in 25 patients, the nasal cavity and paranasal sinuses in 13, cervical lymph nodes in 8, and others in 2. Histologically, 2 had low grade lymphoma, 42 had intermediate grade disease, and 1 had high grade disease. The patients were treated with radiation alone (5 patients), chemotherapy according to a cyclophosphamide, doxorubicin, vincristine, prednisone- (CHOP) regimen (8 patients), or a combination of both treatments (35 patients). In univariate analyses, an unfavorable prognosis was associated with age > or = 60, Stage I disease, and extralymphatic lesion. Multivariate analysis showed that an extralymphatic lesion was a significant independent risk factor for death (p = 0.0093). The overall five-year survival rate was 73.5%. Differences in the treatment was not reflected in the outcome. Our results suggest that a combination of chemotherapy (CHOP) and radiation is an appropriate treatment for lymphatic stage I and II non-Hodgkin's lymphoma of the head and neck. However, more intensive therapy is necessary for patients with extralymphatic head and neck NHL.

Adolescent↗

PubMed1998

Hydrophobilization of esterase by genetic combination with polyproline or polytyrosine at the carboxyl terminal.

Polyproline (Poly-Pro) that is an amphiphilic polypeptide, or polytyrosine (Poly-Tyr) that is a hydrophobic polypeptide, were connected to the carboxy terminus of Pseudomonas sp. esterase by the recombinant DNA technique. The hydrophobicity of the esterase was enhanced by the introduction of Poly-Pro or Poly-Tyr, and also by increasing chain length of the polypeptides. Poly-Tyr increased the hydrophobicity of esterase more than Poly-Pro. Poly-Tyr induced significant conformational change of fusion esterase, but Poly-Pro did not. Consequently, the introduction of Poly-Tyr led to loss of activity of the fusion enzyme to a negligible level. On the other hand, the Poly-Pro-fusion-esterase retained enzymatic activity and the hydrolytic activity (kcat/Km) of the fusion esterase carrying 40 proline residues (esterase-Pro40) relative to that of the wild-type esterase with the substrates p-nitrophenyl-propionate, -pentanoate, and -hexanoate was 1.76, 1.95, and 4.7, respectively. The results could be explained in terms of easier access of long-chain carboxylate to the fusion esterase compared to the wild-type esterase in aqueous solution.

Base Sequence↗

PubMed1998

Hydrophobilization of an esterase by genetic combination with polyproline at the carboxyl terminal

Polyproline, which is an amphiphilic polypeptide, was incorporated into the carboxyl terminal of an esterase by the recombinant DNA technique. The hydrophobicity of the esterase increased with increasing chain length of polyproline without inducing significant conformational changes. The mutant esterase catalyzed the hydrolysis of long-chain carboxylic acid ester more efficiently than the native esterase. It is considered that the alteration of substrate specificity is due to enhanced access of the mutant esterases to hydrophobic substrates. Copyright 1998 John Wiley & Sons, Inc.

Journal Article↗

PubMed1998

Competitive binding assay for thyroxine using in vitro selected oligonucleotides.

A new binding assay that uses oligodeoxyribonucleotides (DNAs) obtained by the in vitro selection method, instead of antibodies, to bind to the target molecule, thyroxine (T4), is described. The DNAs which selectively bound to the T4 were selected, labeled with biotin or radioisotope, and then used to detection of T4 in the presence of liothyronine (T3), which has a chemical structure similar to that of T4.

Biosensing Techniques↗

PubMed1998

Degradation and release profile of microcapsules made of poly[L-lactic acid-co-L-lysine(Z)].

Poly(L-lactic acid-co-L-lysine(Z)) with different Lys(Z) contents was synthesized by Sn(II) salt-catalyzed ring-opening copolymerization of 3(S)-benzyloxycarbonylaminobutyl-6(S)-methylmorpholine-2,5-dione with lactide. Microcapsules of the copolymers were prepared by solvent evaporation from w/o/w emulsion, and FITC-dextran release from the microcapsules was investigated. The FITC-dextran release was dependent on the composition and molecular weight of the copolymers. The release from the microcapsules containing Lys(Z) of 6.5 mol% was slowest among the present microcapsules, which is due to smooth surface and very small microcapsules included in a large microcapsule. On the other hand, the release from microcapsules containing Lys(Z) of 31 or 50 mol% became faster after several days of incubation. GPC measurement of the microcapsules revealed that the copolymers were degraded during the incubation. Cracks and pores were formed on the microcapsule wall. PLLA microcapsules having comparable molecular weight to the copolymers showed neither release acceleration nor degradation in short-time incubation. Therefore, the introduction of Lys(Z) units made PLLA susceptible to degradation to result in delayed acceleration of release.

Calorimetry, Differential Scanning↗

PubMed1998

A novel subtype of G-protein-coupled receptor kinase, GRK7, in teleost cone photoreceptors.

Two kinds of retinal cDNA fragments (OIGRK-R and -C) encoding the putative G-protein-coupled receptor kinases (GRKs) were isolated from medaka, Oryzias latipes. OIGRK-R appears to be closely related to the rhodopsin kinase (RK) found in the outer segments of mammalian photoreceptors, but the deduced amino acid sequence of OIGRK-C shows less than 50% identity to those of GRKs known to date, suggesting that OIGRK-C is a novel GRK subtype (GRK7). The mRNA of OIGRK-R is detectable in rods, and that of OIGRK-C is found in all four types of cone photoreceptor. The C-terminal of OIGRK-R has a consensus sequence for farnesylation, whereas, surprisingly, OIGRK-C has a consensus sequence for geranylgeranylation. Our result are consistent with the concept that lower vertebrates have rod- and cone-specific opsin kinases.

Amino Acid Sequence↗

PubMed1998

Amphiphilic poly(Ala)-b-poly(Sar) microspheres loaded with hydrophobic drug.

Amphiphilic block polypeptides, (Ala)m(Sar)n, were synthesized. Transmission electron microscopy showed that three kinds of block polypeptides, (Ala)42(Sar)21, (Ala)34(Sar)22, and (Ala)34(Sar)27, formed spherical aggregates in water. Dynamic light scattering measurement revealed that the average diameters of (Ala)42(Sar)21 and (Ala)34(Sar)22 aggregates were in the range of 80-90 nm, whilst that of (Ala)34(Sar)27 was about 30 nm. The polypeptides in aqueous solution took a beta-sheet structure, while they took an alpha-helical conformation in trifluoroethanol. These polypeptide aggregates took up 8-anilinonaphthalene-1-sulfonate (ANS), and the capacity of the aggregates for ANS decreased in the order of (Ala)42(Sar)21 > (Ala)34(Sar)22 > (Ala)34(Sar)27. Sumithion, which is a commercial agricultural insecticide, was also taken up by the polypeptide aggregates. When increasing amounts of Sumithion were introduced, (Ala)42(Sar)21 aggregates kept their shape, but (Ala)34(Sar)27 aggregate increased in size. These different behaviors of the polypeptide aggregates were discussed in terms of different structure of aggregates.

Alanine↗

PubMed1998

Thermoresponsive release from poly(Glu(OMe))-block-poly(Sar) microcapsules with surface-grafting of poly(N-isopropylacrylamide).

Thermoresponsive microcapsules were prepared by grafting poly(N-isopropylacrylamide) (PNIPAAm) on the surface of polypeptide (poly(Glu(OMe))-block-poly(Sar) microcapsules. Naked poly(Glu(OMe)-block-poly(Sar) microcapsules were partly hydrolysed with NaOH to remove methyl groups and newly formed carboxyl groups were used to anchor polyallylamine having 4,4'-azobis(4-cyanovaleric acid) groups. Graft polymerization of N-isopropylacrylamide at the microcapsule surface was initiated by photo-cleavage of the azo groups. Microscopic examination showed that a homogeneous dense skin layer of PNIPAAm was formed on the surface of microcapsule at 40 degrees c, while the skin layer became loose when the temperature was lowered to 25 degrees C. Dextran release from the microcapsule was faster below the lower critical solution temperature (LCST) of PNIPAAm than that above it. When the temperature changed across the LCST, a reversible, thermoresponsive release from the microcapsule was observed. Notable, the transition of the release rate by changing the temperature occurs quickly in a narrow temperature range.

Acrylic Resins↗

PubMed1998

Effect of protein and cell behavior on pattern-grafted thermoresponsive polymer.

A thermoresponsive copolymer, poly(Nisopropylacrylamide-co-acrylic acid), was coupled with azidoaniline. The azidophenyl-derivatized copolymer was grafted in a specific pattern on a polystyrene matrix by photolithography. The surface micropattern appeared and disappeared interchangeably, as observed under a phase-contrast microscope, by varying the temperature between 10 degrees C and 37 degrees C. The copolymer-grafted polystyrene surface was hydrophobic at 37 degrees C and hydrophilic at 10 degrees C. Albumin and fibronectin adsorption on the matrix was investigated using the fluorescent-labeling method. Fibronectin adsorbed onto both the grafted and nongrafted regions, while albumin adsorbed more onto the nongrafted regions than the grafted regions. Protein adsorption did not affect surface wettability. Mouse fibroblast STO cells were cultured on tissue culture plates pattern-grafted with the thermoresponsive copolymer. Fibronectin adsorption enhanced cell spreading, while albumin reduced it. When the temperature was lowered, the cells selectively detached from the surface areas grafted with the thermoresponsive copolymer when cultured in serum-free medium; the cells partially detached from these areas when cultured in serum-containing medium. The effect of serum proteins on cell detachment was similar to that caused by a mixture of albumin and fibronectin. Albumin adsorption did not affect the detachment of cells, while fibronectin adsorption inhibited it. The results of the present study indicate that a pattern-grafted, thermoresponsive, azidophenyl-derivatized copolymer can effectively facilitate selective cell detachment under some conditions such as serum-free culture or preadsorption of albumin. The pattern-grafting technique will be useful for qualitative microscopic comparison of surfaces prepared differently on one chip under the same conditions.

Acrylamides↗

PubMed1998

Obui-himo syndrome.

Normal variants of the venous system are relatively common and rarely cause severe symptoms. We report the case of a 5-month-old baby who displayed cyanotic color and swelling of arms whenever she was carried on the mother's back with a special band "Obui-himo". It was demonstrated by venography that the symptoms were caused by the absence of a cephalic vein and compression of axillary veins with the Obui-himo. In any country with a custom similar to the Obui-himo, these symptoms, if clinically encountered, are an indication that venography should be performed.

Arm↗

PubMed1998

Simultaneous activation of two different receptor systems by enkephalin/neurotensin conjugates having spacer chains of various lengths.

Bivalent ligands composed of enkephalin and neurotensin were prepared and their action in the receptor-receptor interaction was studied with the neuroblastoma cell, NG108-15. Enkephalin was connected via oligosarcosine spacer chain to the N-terminus of neurotensin(8-13). The bivalent ligand stimulated the cGMP production more than plain neurotensin. The affinity of the bivalent ligands for the neurotensin receptor changed with varying lengths of the spacer chain. When the spacer chain was an octamer or a dodecamer of sarcosine, the receptor affinity of those bivalent ligands was higher than neurotensin(1-13), and significantly decreased in the presence of excess amount of enkephalin. These results suggest that the bivalent ligands bind to opioid receptor and neurotensin receptor simultaneously, leading to receptor-receptor interaction. On the other hand, some bivalent ligands, especially that without a spacer chain seemed to bind to the neurotensin receptor by the help of the enkephalin part interacting with a receptor exosite.

Animals↗

PubMed1998

Artificial juxtacrine stimulation for tissue engineering.

To endow biomaterials with the ability to regulate cell functions such as proliferation, differentiation, and apoptosis, growth factor proteins were covalently immobilized. The proteins were immobilized on various matrices using different chemical methods. It was shown that insulin and epidermal growth factor stimulated cellular functions even after immobilization. Pattern-immobilization of growth factor proteins clearly demonstrated the stimulation by immobilized proteins. In other words, this type of stimulation by non-diffusional growth factors enabled us to regulate tissue formation with artificial biomaterials. The stimulation was enhanced by coimmobilization with adhesion factors. These stimulations due to the immobilized growth factors may mimic juxtacrine stimulation of membrane-anchored growth factors such as heparin-binding epidermal growth factor, transforming growth factor-alpha, and tumor necrosis factor-alpha.

Animals↗

PubMed1998

Novel chromosomal abnormalities identified by comparative genomic hybridization in parathyroid adenomas.

The molecular basis of parathyroid adenomatosis includes defects in the cyclin D1/PRAD1 and MEN1 genes but is, in large part, unknown. To identify new locations of parathyroid oncogenes or tumor suppressor genes, and to further establish the importance of DNA losses described by molecular allelotyping, we performed comparative genomic hybridization (CGH) on a panel of 53 typical sporadic (nonfamilial) parathyroid adenomas. CGH is a new molecular cytogenetic technique in which the entire tumor genome is screened for chromosomal gains and/or losses. Two abnormalities, not previously described, were found recurrently: gain of chromosome 16p (6 of 53 tumors, or 11%) and gain of chromosome 19p (5 of 53, or 9%). Losses were found frequently on 11p (14 of 53, or 26%), as well as 11q (18 of 53, or 34%). Recurrent losses were also seen on chromosomes 1p, 1q, 6q, 9p, 9q, 13q, and 15q, with frequencies ranging from 8-19%. Twenty-four of the 53 adenomas were also extensively analyzed with polymorphic microsatellite markers for allelic losses, either in this study (11 cases) or previously (13 cases). Molecular allelotyping results were highly concordant with CGH results in these tumors (concordance level of 97.5% for all informative markers/chromosome arms examined). In conclusion, CGH has identified the first two known chromosomal gain defects in parathyroid adenomas, suggesting the existence of direct-acting parathyroid oncogenes on chromosomes 16 and 19. CGH has confirmed the locations of putative parathyroid tumor suppressor genes, also defined by molecular allelotyping, on chromosomes 1p, 6q, 9p, 11q, 13q, and 15q. Finally, CGH has provided new evidence favoring the possibility that distinct parathyroid tumor suppressors exist on 1p and 1q, and has raised the possibility of a parathyroid tumor suppressor gene on 11p, distinct from the MEN1 gene on 11q. CGH can identify recurrent genetic abnormalities in hyperparathyroidism, especially chromosomal gains, that other methods to not detect.

Adenoma↗

PubMed1998

[A search for specific genes working on the process of mycelial growth in Candida tropicalis].

Ethanol has been reported to cause mycelial growth in Candida tropicalis Pk233. Cultivation with ethanol in synthetic media containing glucose gave biphasic growth curves. During the first growth phase, there was an accumulation of swollen spherical yeast cells, instead of the oblong ones observed in the control culture, followed by the appearance of spherical daughter cells in chains. During the second growth phase, pseudohyphal cells appeared, projecting from the swollen yeast cells.Subtractive cloning was performed on cDNAs from both cultures to isolate genes expressed during the first phase, correlating to the process of ethanol induced hyphal growth. Subtracted cDNAs identified by homology search included a homologue of URP2 coding ribosomal protein S20, a homologue of nmt1 coding a regulator gene working on thiamine metabolism, and a homologue of MSG5 coding tyrosine phosphatase. Roles of these cloned homologues were discussed on the process of mycelial growth in this organism.

Candida↗