PubMed Health⌕ Search

Biomedical subjects

K Kitajima

Publications and source records attributed to K Kitajima.

At least 91 records · Page 5Linked to original sources

Myelodysplastic syndrome resembling chronic myeloproliferative disorders in clinicopathological aspects.

We report on a patient with myelodysplastic syndrome (MDS) which resembled chronic myeloproliferative disorder (CMPD). A 67-year-old male was admitted to our hospital in June 1990. A diagnosis of refractory anemia with excess of blasts in transformation (RAEB-T) was based on the peripheral blood and bone marrow findings on admission. However, since thrombocytosis and bone marrow fibrosis was noted, the patient was diagnosed as MDS with myelofibrosis. Low-dose cytosine arabinoside therapy was performed. Although complete remission could not be achieved, a high quality of life could be maintained by appropriate transfusion. In January 1993, the patient was readmitted because of a marked increase in mature neutrophils, showing a moderate increase of blasts, chromosomal aberration (46,XY,12p-) and hepatosplenomegaly; but no fibrosis of bone marrow was observed. These findings suggested that neoplastic proliferation at the level more differentiated to granulocytic lineage occurred at the terminal stage and that his clinical feature was located between MDS and CMPD. This case may be important in considering various aspects of MDS.

Aged↗

Differences between cochlear blood flow and endolymphatic sac blood flow in guinea-pigs.

Cochlear blood flow (CoBF) and endolymphatic sac (ES) blood flow (ESBF) were measured in different groups of guinea-pigs by laser-Doppler flowmetry after the intravenous administration of various drugs through the jugular vein for 60 sec. These drugs included 50% glycerol, 70% isosorbide, 20% mannitol, 7% sodium bicarbonate and 1% diphenidol. For CoBF measurements, a probe was positioned on the basal turn of the right cochlea via a ventral approach. For ESBF measurements, it was placed on the right ES through the posterior cranial fossa via a dorsal approach. The average initial measured value of ESBF (8.31 +/- 2.97 ml/min/100 g) was significantly greater (p < 0.0001) than that of CoBF (4.33 +/- 1.15 ml/min/100 g). Following administration of most drugs except for diphenidol, both CoBF and ESBF increased immediately after administration; however, following diphenidol administration both CoBF and ESBF decreased. The magnitude of the CoBF response tended to be greater than that of the ESBF response (p = 0.006-0.112). It seems likely that this reflects anatomical differences in the vascular supplies, i.e. CoBF from the vertebrobasilar artery and ESBF from the external carotid artery. In addition, the presence of micropores or fenestrations in the ES vasculature may contribute to the differences between CoBF and ESBF.

Animals↗

Involvement of round and oval windows in the vestibular response to pressure changes in the middle ear of guinea pigs.

Changes in ambient pressure can elicit the vertigo and bodily disequilibrium known clinically as alternobaric vertigo. Our previous studies showed that changes in middle ear pressure altered the activity of the primary vestibular neuron, and the finding suggests that the pressure-induced vestibular response causes alternobaric vertigo. To investigate the roles played by the round window (RW) and the oval window (OW) in the vestibular response induced by pressure, we measured the change in perilymphatic pressure and the firing rates of primary vestibular neurons after the application of positive or negative pressure to the middle ear. We found an increase in the pressure-induced vestibular response in the group with a closed OW, and a decrease in the group with a closed RW. Measurements showed that the amplitude of the change in perilymphatic pressure in the group with a closed OW did not differ from that in the control group, whereas the amplitude of the perilymphatic pressure change in the group with a closed RW was significantly reduced. A discrepancy between the number of neurons responding and the amplitude of the perilymphatic pressure change in the closed OW group suggests that the vestibular response induced by the change in middle ear pressure was not related solely to the magnitude of the pressure change in the inner ear, but also involved the oval and round windows.

Animals↗

Synthesis of neoglycoconjugates containing deaminated neuraminic acid (KDN) using rat liver alpha2,6-sialyltransferase.

2-Keto-3-deoxy-D- glycero -D- galacto -nononic acid (KDN) was introduced into asialotransferrin and N -acetyllactosamine (LacNAc) from CMP-KDN by using rat liver Galbeta1-->4GlcNAc alpha2, 6-sialyltransferase to form KDN-transferrin and KDN-LacNAc. These structures contain terminal KDNalpha2-->6Gal-residues, a glycotope that has not yet been described in natural glycoconjugates. KDN was transferred to all four Gal residues in asialotransferrin by this enzyme. The incorporation efficiency of KDN from CMP-KDN into asialotransferrin was about half that of Neu5Ac from CMP-Neu5Ac, based on the V max/ K m values for these donor substrates, 0.0527 min-1and 0.119 min-1, respectively. The KDNalpha2-->6Gal linkage was resistant to exosialidase treatment, in contrast to the sensitivity of the Neu5Acalpha2-->6Gal linkage. Interestingly, Sambucus sieboldiana agglutinin (SSA) was shown to prefer KDN-transferrin to the corresponding Neu5Ac-transferrin, as estimated by slot-blot analysis. The use of an alpha2,6-sialyltransferase to synthesize neoglycoproteins containing KDN has not been previously reported. Their facile synthesis using CMP-KDN and sialyltransferases with different specificities offers new possibilities to study the function of neo-KDN-glycoconjugates, and to explore their use in glycotechnology.

Amino Sugars↗

Cloning and expression of an alpha-2,8-polysialyltransferase (STX) from Xenopus laevis.

Polysialic acid (polySia) is a carbohydrate structure found on neural cell adhesion molecules (N-CAM). Two polysialyltransferases (polySiaTs) that catalyze synthesis of polySia have been described, and designated PST-1/PST/ST8SiaIV and STX/ST8SiaII. We cloned a polySiaT (xSTX) from a nonmammalian vertebrate, Xenopus laevis . xSTX had 80% amino acid similarity to the rat STX. This clone induced polySia expression when transfected into polySia-negative COS-1 cells. Northern blot analysis of whole embryos at different stages of development revealed that xSTX mRNA was most abundantly expressed in premetamorphic stages. The relative level of xSTX and N-CAM mRNAs was also examined and found to change in parallel to the extent of polysialylation on N-CAM. In adult tissues, the expression of xSTX mRNA was restricted to brain, eye and heart, which also expressed polySia. These results suggest that xSTX is the major enzyme responsible for the synthesis of polysialylated N-CAM in embryos at certain stages of development and also in adult tissues.

Amino Acid Sequence↗

Effectiveness of polyclonal and monoclonal antibodies prepared for an immunoassay of the etofenprox insecticide.

Two polyclonal antibodies and three monoclonal antibodies specific to the etofenprox insecticide were prepared from rabbits and mice, respectively. The monoclonal antibodies were more reactive with etofenprox than the polyclonal antibodies by C-ELISA. Monoclonal antibody cl 205-65 was found to be the most tolerant to methanol, most highly reactive and most specific to etofenprox among the antibodies tested.

Animals↗

Immunohistochemical detection of vasoactive intestinal polypeptide (VIP) and the VIP receptor in the rat inner ear.

Vasoactive intestinal polypeptide (VIP) is a 28 amino acid peptide that was originally isolated from porcine duodenum. The presence of VIP has been demonstrated in the central nervous system and peripheral tissues. However, there have been few reports on VIP as a neurotransmitter, especially in the inner ear. To investigate the function of VIP in the rat inner ear, we examined the expression of VIP and the VIP receptor by immunohistochemistry. Using the anti-VIP and VIP receptor antibodies, scattered fibres in the cochlear nerve trunk demonstrating VIP-like immunoreactivity were found, and the spiral ganglion cells demonstrated ring-shaped VIP-like immunoreactivity. Immunoreactivity for the VIP receptor was predominantly found in the spiral ganglion cells. Our results suggest that VIP may play an important role as a possible neurotransmitter not only in the local control of cochlear blood flow, but also in the auditory system.

Animals↗

Mouse gene trap approach: identification of novel genes and characterization of their biological functions.

The mouse gene trap strategy is an insertional mutagenesis involving an exogenous DNA, termed the trap vector, as a mutagen that produces a mutation in the mouse genome and a sequence tag to facilitate the isolation of the mutated genes. The trap vector consists of a reporter gene whose expression mimics that of the endogenous genes mutated and a selection marker that sorts cells bearing the inserted vector. Gene trap is a powerful method for identifying genes important in biological phenomena. Moreover, the method produces mutant organisms whose phenotypes provide invaluable information about the biological functions of the genes responsible for these phenotypes. Indeed, a number of genes essential for mouse embryogenesis have been identified by the gene trap method. Here, we describe the principle, results, and perspectives for applications of gene trap approach to the study of cell differentiation and lineage commitment.

Animals↗

Surgical observations on the endolymphatic sac in Meniere's disease.

OBJECTIVE: This study aimed to clarify the pathoanatomic characteristics of the endolymphatic sac in Meniere's disease by surgical observations. STUDY DESIGN: The study design was a retrospective case study conducted in the setting of University Hospital at Shiga University of Medical Science. PATIENTS: Studied were 101 patients with Meniere's disease who underwent endolymphatic sac drainage surgery at the university hospital by the same surgical team between 1984 and 1995. Control group consisted of 23 patients with non-Meniere's disease. MAIN OUTCOME MEASURES: Photographs were taken of the sac in 101 patients with Meniere's disease during endolymphatic sac drainage surgery, and the pathoanatomic findings of the sacs were classified into three grades regarding position (types I, II, III), size (large, intermediate, small), color (red, intermediate, white), and vascularity (fair, intermediate, poor). Statistical difference was studied between Meniere's group and non-Meniere's group by chi-square test. RESULTS: The patients with Meniere's disease were found to have endolymphatic sacs located inferiorly to the posterior semicircular canal, very close to the jugular bulb (type III) (p < 0.001). The sacs also were smaller in size (p = 0.068), whiter in surface color (p = 0.0036, 0.01), and of less vascularity (p = 0.051) than those of the patients with non-Meniere's disease. The comparisons showed significant differences only in position and color. CONCLUSION: The patients with Meniere's disease were found to have endolymphatic sacs located inferiorly to the posterior semicircular canal, very close to the jugular bulb. The sacs also were whiter in surface color.

Endolymphatic Sac↗

[A case of hypothalamic hamartoma manifesting gelastic seizure and multifocal independent seizure foci].

A 25-year-old man manifesting gelastic seizure in association with hypothalamic hamartoma was reported. The epileptogenic focus was evaluated by long-term video EEG monitoring, single photon emission computed tomography (SPECT) and positron emission tomography (PET). Multiple independent ictal foci were found in the ictal EEG recording, and glucose metabolism and cerebral blood flow were decreased in scattered cortical areas. Facial asymmetry seen during gelastic seizure in this case may be caused by contraction of mimetic contralateral to the ictal focus in the temporal lobe.

Adult↗

Benzoquinones inhibit the expression of inducible nitric oxide synthase gene.

Benzoquinones inhibited the production of NO induced by LPS and gamma-IFN in C6 glia cells. The mechanistic studies showed that benzoquinones inhibited the expression of iNOS mRNA through inactivation of NF kappa B. Benzoquinones may be a useful candidate for the development of a drug to treat disease due to iNOS gene over-expression.

Animals↗

Vasopressin and oxytocin receptor mRNAs are expressed in the rat inner ear.

The cause of endolymphatic hydrops, a characteristic finding in Menière's disease, is not known. To study the possible involvement of the neurohormones vasopressin and oxytocin in this condition, we investigated whether transcripts of the genes encoding the arginine vasopressin (AVP) and oxytocin receptors are expressed in the rat inner ear. Utilizing the reverse transcription-polymerase chain reaction (RT-PCR) method, primers specific for each receptor showed a single message band of the expected size in the rat inner ear. When the PCR products were cloned, the sequences were identical to those of the real-type (V2) AVP receptor and oxytocin receptor transcripts. The finding of vasopressin and oxytocin receptor mRNAs in the inner ear suggests that these neurohypophyseal hormones may have roles in the regulation of inner ear fluid. In particular, the presence of vasopressin receptor mRNA in the inner ear supports the hypothesis of a relationship between high plasma vasopressin levels and endolymphatic hydrops.

Animals↗

Site-specific de-N-glycosylation of diglycosylated ovalbumin in hen oviduct by endogenous peptide: N-glycanase as a quality control system for newly synthesized proteins.

Hen ovalbumin (OVA) is known to exist as a singly N-glycosylated form with a glycan chain on Asn-292 in egg white. Previous studies showed that di-N-glycosylated form of OVA [Di-OVA; CHO-Asn-292/CHO-Asn-311 (CHO, N-glycan chain)], which has two N-glycan chains on Asn-292 and Asn-311, was expressed only transiently in hen oviduct. Di-OVA was not found in egg white, suggesting that this form cannot be secreted normally and may possibly be converted to mono-N-glycosylated OVA (CHO-Asn-292/Asp-311) by the action of peptide:N-glycanase (PNGase) during synthesis and secretion. In this study, we have identified the putative PNGase activity in the homogenate of hen oviduct, purified 1,000-fold, and designated as PNGase HO. We examined the reactivity of Di-OVA to PNGase HO and found that this enzyme site-specifically cleaved off the glycan chain at Asn-311 to convert Di-OVA into the mono-N-glycosylated form (CHO-Asn-292/Asp-311). In contrast, this enzyme was found not to act on the mono-N-glycosylated OVA (CHO-Asn-292/Asn-311) found in egg white when it was tested as a substrate. The present findings support our view that de-N-glycosylation catalyzed by PNGase may be involved in quality control of newly synthesized proteins by converting its diglycosylated form into the mono-N-glycosylated form that can be secreted. However, the alternative possibility that de-N-glycosylation may trigger cytosolic degradation of the aberrantly glycosylated glycoprotein cannot be ruled out.

Amidohydrolases↗

Catalysis by a new sialidase, deaminoneuraminic acid residue-cleaving enzyme (KDNase Sm), initially forms a less stable alpha-anomer of 3-deoxy-D-glycero-D-galacto-nonulosonic acid and is strongly inhibited by the transition state analogue, 2-deoxy-2, 3-didehydro-D-glycero-D-galacto-2-nonulopyranosonic acid, but not by 2-deoxy-2,3-didehydro-N-acetylneuraminic acid.

Deaminoneuraminic acid residue-cleaving enzyme (KDNase Sm) is a new sialidase that has been induced and purified from Sphingobacterium multivorum. Catalysis by this new sialidase has been studied by enzyme kinetics and 1H NMR spectroscopy. Vmax/Km values determined for synthetic and natural substrates of KDNase Sm reveal that 4-methylumbelliferyl-KDN (KDNalpha2MeUmb, Vmax/Km = 0.033 min-1) is the best substrate for this sialidase, presumably because of its good leaving group properties. The transition state analogue, 2, 3-didehydro-2,3-dideoxy-D-galacto-D-glycero-nonulosonic acid, is a strong competitive inhibitor of KDNase Sm (Ki = 7.7 microM versus Km = 42 microM for KDNalpha2MeUmb). 2-Deoxy-2, 3-didehydro-N-acetylneuraminic acid and 2-deoxy-2, 3-didehydro-N-glycolylneuraminic acid are known to be strong competitive inhibitors for bacterial sialidases such as Arthrobacter ureafaciens sialidase; however, KDNase Sm activity is not significantly inhibited by these compounds. This observation suggests that the hydroxyl group at C-5 is important for recognition of the inhibitor by the enzyme. Reversible addition of water molecule (or hydroxide ion) to the reactive sialosyl cation, presumably formed at the catalytic site of KDNase Sm, eventually gives rise to two different adducts, the alpha- and beta-anomers of free 3-deoxy-D-glycero-D-galacto-nonulosonic acid. 1H NMR spectroscopic studies clearly demonstrate that the thermodynamically less stable alpha-form is preferentially formed as the first product of the cleavage reaction and that isomerization rapidly follows, leading to an equilibrium mixture of the two isomers, the beta-isomer being the major species at equilibrium. Therefore, we propose that KDNase Sm catalysis proceeds via a mechanism common to the known exosialidases, but the recognition of the substituent at C-5 by the enzyme differs.

Flavobacterium↗

Activity of UDP-GlcNAc:GlcNAc beta 1-->6(GlcNAc beta 1-->2) Man alpha 1-->R[GlcNAc to Man] beta 1-->4N-acetylglucosaminyltransferase VI (GnT VI) from the ovaries of Oryzias latipes (Medaka fish).

UDP-GlcNAc:GlcNAc beta 1-->(GlcNAc beta 1-->2)Man alpha 1-R[GlcNAc to Man] beta 1-->4N-acetylglucosaminyltransferase VI (GnT VI) activity was shown to be present in crude homogenates of Medaka fish (Oryzias latipes) ovaries using UDP-[14C]GlcNAc and synthetic GlcNAc beta 1-->6 (GlcNAc beta 1-->2)Man alpha 1-->6Glc beta 1-->octyl as substrates. Characterization of this activity showed a pH optimum at about pH 7.0 and an absolute requirement for divalent cations. The optimum concentration of Mn2+ was at about 25 mM. This finding is the first report on GnT VI activity in fish; the enzyme has previously been described only in avian tissues.

Animals↗

Detection of C-type natriuretic peptide (CNP) and atrial natriuretic peptide (ANP-B) receptor mRNAs in rat inner ear.

C-Type natriuretic peptide (CNP) is the third member of the natriuretic peptide family which plays an important role in body fluid homeostasis. To determine a possible role of CNP in regulation of an inner ear fluid, we investigated the expression of CNP and atrial natriuretic peptide B receptor (ANP-B receptor) mRNAs in rat inner ear using a reverse transcription polymerase chain reaction (RT-PCR) method. Amplification products with sizes expected for CNP and ANP-B were detected in the inner ear. After cloning and analysis, the sequences for PCR products were identical to those of CNP or ANP-B receptor in the brain. These results indicate that both CNP and ANP-B receptor are expressed in the inner ear of the rat and suggest that CNP may play a role in inner ear function (such as regulation of inner ear fluid) in an autocrine and/or paracrine manner.

Animals↗

Primary ectopic meningioma in the right ethmoid sinus: a case report.

A 29-year-old female with primary ectopic meningioma in the right ethmoid sinus was reported. She was treated by a right lateral rhinotomy with total removal of the tumor and the subsequent clinical course was good. Contrast enhanced magnetic resonance image (MRI) was most informative to define the tumor and decide the surgical procedure, in which it was demonstrated as well circumscribed mass lesion with considerable homogeneous contrast enhancement.

Adult↗