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Biomedical subjects

M Iwasaki

Publications and source records attributed to M Iwasaki.

At least 19 recordsLinked to original sources
PubMed1992

Fish egg glycophosphoproteins have species-specific N-linked glycan units previously found in a storage pool of free glycan chains.

Recent findings (Ishii, K., Iwasaki, M., Inoue, S., Kenny, P. T. M., Komura, H., and Inoue, Y. (1989) J. Biol. Chem. 264, 1623-1630; Inoue, S., Iwasaki, M., Ishii, K., Kitajima, K., and Inoue, Y. (1989) J. Biol. Chem. 264, 18520-18526) of a relatively large quantity of complex-type free sialo-oligosaccharides in the unfertilized eggs of freshwater fish, Plecoglossus altivelis and Tribolodon hakonensis, prompted us to search for their progenitor glycoproteins. First we demonstrated a third occurrence of free sialoglycans in the unfertilized eggs of Medaka fish (Oryzias latipes). Next, in all three species studied, a uniformly high level of glycophosphoproteins (GPP) was identified and found to possess N-linked glycan units. The carbohydrate structures of the GPP were determined to be identical with those of the free glycans isolated from the unfertilized eggs of the respective fish species. Thus, the most likely candidate for the progenitor of free sialoglycans appeared to be the oocyte GPPs. This implies that the liberation of the free glycans by a putative peptide-N4-(N-acetyl-beta-glucosaminyl)asparagine amidase may represent a necessary biochemical event during vitellogenesis or oogenesis. The present results may provide insight into a new concept of a "protein N-glycosylation/de-N-glycosylation system" recently proposed by us (Seko, A., Kitajima, K., Inoue, Y., and Inoue, S. (1991) J. Biol. Chem. 266, 22110-22114).

Amino Acids↗
PubMed1992

Roles of residues 129 and 209 in the alteration by cytochrome b5 of hydroxylase activities in mouse 2A P450S.

Cytochrome b5 stimulates the coumarin 7-hydroxylation activity of P450coh. A mutation of Arg-129 in P450coh, however, abolishes the stimulation. Moreover, this mutant P450coh binds loosely to cytochrome b5-conjugated Sepharose 4B, whereas wild-type P450coh binds tightly. Consistent with this, the mutation increases the Ka value for b5 binding approximately 6-fold. The identity of residue 209 also alters the stimulation of the activity of P450coh depending on the type of the substrates used and products formed. Coumarin 7-hydroxylation activity is greatly stimulated by cytochrome b5 only when Phe is at position 209, while cytochrome b5 stimulates testosterone hydroxylation activity of P450coh in which Phe, Asn, Ser or Lys substitutes residue 209. P450coh changes its rate of hydrogen peroxide formation depending on the identity of residue 209 and substrate used. Cytochrome b5 decreases the hydrogen peroxide formation of some P450coh whose activities are stimulated by the cytochrome; however, the decrease does not always result in stimulating the activity. The results indicate, therefore, that residues 129 and 209 play different roles in stimulating P450coh activity by cytochrome b5; Arg-129 is a key residue in the cytochrome b5-binding domain and is essential for the stimulation. Residue 209, however, alters the efficiency of electron transport for substrate oxidation as a residue which resides near the sixth ligand of heme and in the substrate-binding site.

Animals↗
PubMed1992

cDNA cloning of a novel heterogeneous nuclear ribonucleoprotein gene homologue in Caenorhabditis elegans using hamster prion protein cDNA as a hybridization probe.

The mammalian prion protein (PrPc) is a cellular protein of unknown function, an altered isoform of which (PrPsc) is a component of the infectious particle (prion) thought to be responsible for spongiform encephalopathies in humans and animals. The evolutionary conservation of the PrP gene has been reported in the genomes of many vertebrates as well as certain invertebrates. In the genome of nematode Caenorhabditis elegans, the sequence capable of hybridizing with the mammalian PrP cDNA probe has been demonstrated, predicting the presence of the PrP gene homologue in C.elegans. In this study, Southern analysis with the hamster PrP cDNA (HaPrP) probe confirmed the previous observation. Moreover, Northern analysis revealed that the sequence is actively transcribed in adult worms. Thus, we screened C.elegans cDNA libraries with the HaPrP probe and isolated a cDNA that hybridizes to the same sequence in C.elegans that hybridized with the HaPrP probe in the Southern and Northern analyses. The deduced amino acid sequence of this cDNA, however, is substantially homologous with heterogeneous nuclear ribonucleoprotein (hnRNP) core proteins rather than mammalian PrPc. The hnRNPs contain the glycine-rich domain in the C-terminal half of the molecule, which also seemed to be in PrPc at the N-terminal half of the molecule. Both of the glycine-rich domains are composed of tracts with high G + C content, indicating that these tracts may due to the hybridizing signals. These results suggest that this cDNA clone is derived from a novel hnRNP gene homologue in C.elegans but not from a predicted PrP gene homologue.

Amino Acid Sequence↗
PubMed1992

Interphotoreceptor matrix in the human retina: cone-like domains surround a small population of rod photoreceptors.

The interphotoreceptor matrix (IPM) in mammalian retinas is subdivided into rod and cone specific compartments: peanut agglutinin (PNA) binding glycoconjugates are associated with cones, whereas wheat germ agglutinin (WGA) binding glycoconjugates are associated with rods. To establish the identity of a photoreceptor cell type in the human retina with rod dimensions but with a matrix domain which stains with PNA, double label studies, using PNA-ferritin to decorate the extracellular domains and immunocytochemical techniques using a rod specific anti-opsin antibody were conducted. The PNA-binding domains were observed in the cone-associated IPM as well as in the IPM surrounding a small population of rod-shaped photoreceptors. The outer segments of these rod-shaped photoreceptors showed intense labeling with a rod specific anti-opsin antibody as did all other rods which were free of PNA-labeling. A quantitative analysis of all retinal quadrants indicates that this novel rod represents approximately 0.3% of the total rod population in the human retina.

Arachis↗
PubMed1992

Collagen gene expression during chondrogenesis from chick periosteum-derived cells.

Chick periosteum-derived cells, which do not enter the chondrogenic cell lineage during normal bone development and growth, exhibit chondrogenic potential in high cell density culture conditions. In such cultures, collagen gene expression was temporally analyzed at the mRNA level by a reverse transcription PCR (RT-PCR) procedure, which showed that alpha 1(II) and alpha 1(IX) collagen mRNAs are coordinately increased, coincident with the onset of overt chondrogenesis, and subsequently decreased as chondrocytes exhibited hypertrophic characteristics. alpha 1(X) collagen mRNA was detected well before the onset of chondrogenesis and markedly increased along with the hypertrophic change. For alpha 2(I) collagen, both the bone/tendon form and the cartilage form of mRNA were detected throughout the culture period. This culture system provides an experimental vehicle capable of investigating the molecular events involved in the full range of chondrogenic differentiation starting from uncommitted periosteum-derived mesenchymal stem cells.

Animals↗
PubMed1992

Proteoglycans in the mouse interphotoreceptor matrix. V. Distribution at the apical surface of the pigment epithelium before and after retinal separation.

The distribution of chondroitin sulfate proteoglycans in the mouse interphotoreceptor matrix (IPM) proximal to the retinal pigment epithelium (RPE) was evaluated with EM histochemical techniques using Cupromeronic Blue (CmB) before and after retinal separation. Densely packed, sheet-like processes surrounding vesicle-like compartments containing CmB staining were normal constituents of the IPM at the apical surface of the RPE. Most of the vesicle-like compartments, which appeared to be isolated from the IPM in single section profiles, were found to be continuous with the IPM when three-dimensional reconstructions of serial thin sections were evaluated. Analyses of stereo image pairs of semithin sections visualized by electron spectroscopic imaging (ESI) also demonstrated that the CmB stained proteoglycans in the lumen of these pseudovesicles were in continuity with the CmB stained components present in the IPM. Moreover, ESI demonstrated that the CmB stained profiles formed an elaborate interconnecting network extending from the apical border of the RPE to the level of the outer limiting membrane of the retina. After removal of the retina, rinsing of the RPE with Ringer's solution prior to fixation eliminated proteoglycan staining near the base of the apical processes, whereas staining near the tips of these processes remained. The CmB stained filaments remaining after rinsing were thicker and shorter, and made fewer interconnections than those in the non-separated preparations. These results suggest that two types of chondroitin sulfate proteoglycans are present in the IPM which differ in distribution and in the degree of aqueous solubility. Additionally, a closely associated retina appears to be required for maintenance of the normal structure of proteoglycans associated with the RPE surface. The elaborate topography at the RPE apical surface may play a role in the delivery and/or recovery of components of the IPM.

Animals↗
PubMed1992

Extramedullary plasmacytoma (EMP) of urinary bladder.

An extramedullary plasmacytoma (EMP) is presented with an isolated lesion in the urinary bladder accompanying an IgG-K paraproteinemia. After a short-term oral melphalan administration, the tumor soon regressed together with the paraprotein, and has never recurred during the two-year follow-up. This is the fourth case of primary EMP of the urinary bladder reported in the literature.

Aged↗
PubMed1992

Regulation of Drosophila neural development by a putative secreted protein.

The Drosophila strawberry (sty) locus was isolated by P-element insertion mutagenesis in a screen for mutations affecting eye development. Analysis of the mutant phenotype and the putative expression pattern of the sty gene suggested that it has multiple functions. Mutations in the sty gene lead to irregular spacing of ommatidia, an increase in the number of photoreceptor cells, as well as abnormal axonal projections to the lamina and disrupted structure of the optic lobes in the adult fly. The sty mutation also causes abnormal head involution, a change in a number of sensilla in the antennomaxillary complex in the embryonic stage and abnormal morphogenesis of the maxillary palp and wings in later stages. We examined the presumptive expression of the sty gene during development by histochemical staining for lacZ expression from enhancer trap elements inserted within the sty gene. During embryogenesis, expression of lacZ showed a segmental pattern in the ectoderm and in the nervous system. In the eye imaginal discs, lacZ was expressed in photoreceptor cells beginning a few rows posterior to the morphogenetic furrow. The lacZ was also expressed in the wing disc. In the adult, lacZ was expressed in the retina and lamina. We cloned the sty gene by P-element tagging and found that it encodes a putative secreted protein containing a cysteine-rich region similar to the epidermal growth factor (EGF) repeat. On the basis of the loss of functional phenotype, the expression pattern and the predicted structure of its product, we propose that sty encodes a diffusible protein acting as a signal involved in lateral inhibition within the developing nervous system and also as a factor involved either directly or indirectly in axonal guidance and optic lobe development.

Animals↗
PubMed1992

Gomisin A inhibits tumor promotion by 12-O-tetradecanoylphorbol-13-acetate in two-stage carcinogenesis in mouse skin.

Gomisin A, isolated from the fruits of Schisandra chinensis, is one of the dibenzocyclooctadiene lignans. Application of 12-O-tetradecanoylphorbol-13-acetate (TPA, 1 microgram/ear), a tumor-promoting agent, to the ears of mice induces inflammation. Among seven dibenzocyclooctadiene lignans assayed, gomisin A, gomisin J, and wuweizisu C inhibited the inflammatory activity induced by TPA in mice. The ED50 of these compounds for TPA-induced inflammation was 1.4-4.4 mumol. Gomisin A, with an ED50 of 1.4 mumol, showed the strongest inhibitory effect. Furthermore, at 5 mumol/mouse, it markedly suppressed the promotion effect of TPA (2.5 micrograms/mouse) on skin tumor formation in mice following initiation with 7,12-dimethylbenz[a]anthracene (50 micrograms/mouse). It is assumed that the inhibition of tumor promotion by gomisin A is due to its anti-inflammatory activity.

Animals↗
PubMed1992

Pulmonary intralobar sequestration accompanied by aneurysm of an anomalous arterial supply.

A 47-year-old woman presented with hemoptysis and her chest X-ray films showed an opacity suggesting a mass in the left lower lung field. Based on radiographic investigations, the mass was diagnosed as an aneurysm develop in an anomalous vessel and was considered to be a Pryce type I pulmonary intralobar sequestration. Resection of the left lower lobes was performed and the aneurysm was found to be filled with thrombus. It is rare for an aneurysm to form in an aberrant vessel. This complication may have been the result of regional sclerosis affecting the anomalous artery as well as systemic atherosclerosis.

Aneurysm↗
PubMed1992

[Trial of in vitro fertilization via epididymal duct aspirated sperm].

We made a trial of our method by which sperm are collected directly from epididymal duct, then subjected to in vitro fertilization. The subjects were a total of 22 cases comprising 14 of obstructed azoospermia and 8 of severe oligoasthenozoospermia, on which the surgery was performed 26 times. Using the microscope, an epididymal duct was directly punctured to make a suction of the fluid or was slightly incised to make a suction of the outflow. Sperms thus collected were preincubated for 4 to 6 hours, then subjected to in vitro fertilization. Condition of collected sperms; 32 x 10(4)-15300 x 10(4) sperms were obtained in real number. Sperm motility rate was 0-82%, averaging 25.0%. Sperm forward motility were fairly good in 18 of 26 test cases. Sperm condition was so poor as to make the insemination impossible in 4 test cases (16%). Fertility rate for cases of obstructed azoospermia was 53% (8/15 test cases) and 63% (55/87 eggs) in the test cases and the number of eggs, respectively, compared with 33% (2/6 test cases) and 5.4% (2/37 eggs), respectively for cases of oligo-asthenozoospermia. Pregnancy; Successful pregnancy was obtained in 2 of the cases of obstructed azoospermia, in each of which sperms were collected from the head of the epididymis, then passed into the maternal body by zygote intra fallopian tubal transfer (ZIFT); with the one case resulting in uneventful delivery in November 1991 and the other in a miscarriage. The above results suggested the present method would become an epoch-making approach in the treatment of severe male infertility.

Epididymis↗
PubMed1992

[Diagnostic significance of angiography for small hepatocellular carcinoma--comparison with other examinations].

The diagnostic value of angiography for small hepatocellular carcinoma was evaluated in comparison with histology, contrast-enhanced computed tomography, and ultrasonography. A total of 120 patients with small hepatocellular carcinoma (less than 3 cm in size) were examined. The definitive detection rate for primary tumors less than 2 cm in size was 44.9% by angiography, while it was 68.6% for primary tumors between 2 cm and 3 cm in size. When the primary tumor was less than 2 cm in size and without tumor vessels on angiography, it tended to be of Edmondson's grade 1 and to show fatty change. When the primary tumor was less than 2 cm in size and without tumor stain while non-cancerous parenchyma showed irregular stain, it tended to be of Edmondson's grade 1 and normotrabecular type. Angiography was found to be of particular value in detecting satellite tumors with a nodular parenchymal echo pattern in non-cancerous areas, because ultrasonography often fails to differentiate these satellite tumors from non-affected parenchyma.

Adult↗
PubMed1992

[A case of mediastinal teratoma--differentiation from lung abscess and bronchogenic carcinoma].

A 38-year-old man was admitted with persistent productive cough and right anterior chest pain. Chest X-ray showed two large masses connected with each other, one in the right lung field and the other in the anterior mediastinum. A tentative diagnosis of either lung abscess or bronchogenic carcinoma was initially made, because of elevated serum tumor markers (SLX and SCC) and persisting refractory inflammatory sings. However, open chest drainage revealed a few fine hairs and atheromatous materials within the masses, and the diagnosis of teratoma was made. We removed these masses, and investigated the reason for the elevation of tumor markers. Staining with SLX monoclonal antibody demonstrated that the pancreatic tissue in the masses contained SLX. Although this is the first reported case of teratoma producing tumor marker (SLX), it is highly possible that tumor markers may be elevated in the majority of patients with teratoma because of the genesis of this tumor.

Adult↗
PubMed1992

Laminoplasty versus subtotal corpectomy. A comparative study of results in multisegmental cervical spondylotic myelopathy.

A comparative study of surgical results was used to determine the treatment of choice for multisegmental cervical spondylotic myelopathy. Forty-one patients who received subtotal corpectomy and strut grafting (SCS) and forty-two undergoing laminoplasty were followed up for at least 2 years after surgery. Regarding factors known to affect surgical prognosis (age at surgery, duration of symptoms, severity of neurologic deficit, anteroposterior canal diameter, transverse area of the cord at the site of maximum compression, number of levels involved), the two groups were statistically comparable with each other. The severity of neurologic deficits was assessed by the Japanese Orthopaedic Association scale. Results were evaluated in terms of postoperative score and recovery rate. The difference between the recovery rate and final score between the two groups was not statistically significant. Surgical complications were more frequent in the subtotal corpectomy and strut grafting group than in the laminoplasty group. The most frequent complications encountered in the subtotal corpectomy and strut grafting group were related to bone grafting. Spinal alignment worsened in six patients of the laminoplasty group, but none of them suffered from neurologic deterioration. Another disadvantage of subtotal corpectomy and strut grafting was the longer postoperative period of bed rest needed to secure graft stability. We conclude that laminoplasty should be the treatment of choice for multisegmental cervical spondylotic myelopathy when neurologic results, incidence of complications, and postoperative treatment are taken into consideration.

Aged↗
PubMed1992

[Renal and neurologic symptoms due to cryoglobulinemia complicated with rheumatoid arthritis and Sjögren's syndrome].

A 55-year-old woman with rheumatoid arthritis and Sjögren's syndrome developed complications of acute renal failure and symmetrical polyneuropathy. Laboratory examination revealed macroglobulinemia, positive cryoglobulin, and low complement levels. Kidney biopsy specimen revealed "thrombi" in glomerular capillary loops that were positive for PAS stain and negative for Congo red stain. Sural nerve biopsy specimens showed axonal degeneration and subsequent myelin loss due to vasculitis. We, therefore, diagnosed renal failure and polyneuropathy due to cryoglobulinemia, and treated the patient with double filtration plasmapheresis. Moreover, lymph node biopsy specimen revealed malignant lymphoma of the follicular, small-cell lymphoplasmocytic type which seemed to be related to the macroglobulinemia. The complication of cryoglobulinemia must be taken into consideration in patients with autoimmune disease or lymphoproliferative disorder complicated with renal or neurologic symptoms.

Acute Kidney Injury↗
PubMed1992

[Operation of pleural dissemination of thymoma].

Nine patients underwent operation for pleural dissemination of thymoma and received radiotherapy postoperatively. In 5 patients dissemination was resected along with the invasive thymoma at the initial operation. In 6 patients resection of a part of the diaphragm was needed. In 4 patients recurrent dissemination of thymoma appeared in the phrenico-costal sinus, where not only the location of dissemination but also postoperative radiotherapy had not been performed properly at the time of the previous operation. Seven are alive 2 months to 7 years 10 months after the first operation for dissemination. Two died respectively 7 years and 3 years 5 months after the first operation for dissemination.

Adult↗