Biomedical subjects

F Ito

Publications and source records attributed to F Ito.

At least 145 records · Page 8Linked to original sources

PubMed1993

Arachidonic acid-selective cytosolic phospholipase A2 is crucial in the cytotoxic action of tumor necrosis factor.

The role of phospholipase A2 (PLA2) in the cytotoxic action of tumor necrosis factor (TNF) was examined. Recently, we described the characterization of TNF-resistant sublines isolated from TNF-sensitive cell line L929 (Hayakawa, M., Oku, N., Takagi, T., Hori, T., Shibamoto, S., Yamanaka, Y., Takeuchi, K., Tsujimoto, M., and Ito, F. (1991) Cell Struct. Funct. 16, 333-340). The most remarkable features of these TNF-resistant sublines were the defects in TNF-stimulated arachidonate metabolism. In this study, we characterized the PLA2 activities of these sublines and found a significant decrease in the activity in one of the TNF-resistant sublines, C12 cells. The enzymological features, such as Ca2+ requirement and substrate specificity, suggested that the high molecular weight arachidonoyl-selective cytosolic PLA2 (cPLA2) was involved in the TNF action. Northern hybridization analysis demonstrated the reduced expression of high molecular weight cPLA2 in C12 cells. Furthermore, expression of a cloned cPLA2 cDNA in C12 cells increased the sensitivity of cells to the TNF cytotoxicity. These results indicate the crucial role of the high molecular weight cPLA2 in the TNF-induced cytolysis.

Animals↗

PubMed1993

Synthesis of CMP-deaminoneuraminic acid (CMP-KDN) using the CTP:CMP-3-deoxynonulosonate cytidylyltransferase from rainbow trout testis. Identification and characterization of a CMP-KDN synthetase.

The sugar nucleotide, cytidine 5'-(3-deoxy-D-glycero-D-galacto-2-nonulosonic phosphate) (CMP-KDN) is expected to serve as a donor of KDN residues in the synthesis of KDN-containing glycoconjugates. We report here the identification and characterization of CMP-KDN synthetase, a novel enzyme responsible for synthesis of CMP-KDN from KDN and CTP. The enzyme was partially purified from the testis of rainbow trout (Oncorhynchus mykiss), where KDN gangliosides were first discovered (Yu, S., Kitajima, K., Inoue, S., and Inoue, Y. (1991) J. Biol. Chem. 266, 21929-21935), and used to synthesize CMP-[14C]KDN, which was characterized by 1H NMR. Vmax/Km studies showed that KDN was a preferred nonulosonic acid substrate compared to N-acetylneuraminic acid (Neu5Ac) or N-glycolylneuraminic acid (Neu5Gc) (4.4 x 10(-3) min-1 for KDN versus 2.3 and 1.8 x 10(-3) min-1 for Neu5Ac and Neu5Gc, respectively). CMP-KDN synthetase activity was maximal at pH 9-10 and at 25 degrees C. The presence of either Mg2+ or Mn2+ was essential for CMP-KDN synthetase activity. 25 mM Mg2+ stimulated formation of CMP-KDN more than 10-fold, yet only stimulated formation of CMP-Neu5Ac and CMP-Neu5Gc 4-fold, relative to 1 mM Mg2+. A kinetic study using mixed substrates showed that both CMP-KDN and CMP-Neu5Ac synthetase activities in the partially purified enzyme were due to the same active site of a single enzyme. In contrast, Neu5Ac and Neu5Gc were the preferred nonulosonic acid substrates for the calf brain CMP-sialic acid synthetase. Thus, mammalian CMP-sialic acid synthetases recognizes similar, yet distinctively different, substrate specificity determinants. Thus, the trout testis enzyme was considered to synthesize activated sugar nucleotides required for synthesis of both (KDN)GM3 and (Neu5Ac)GM3. The expression of CMP-KDN synthetase was shown to be temporally correlated with development and to parallel the developmental expression of (KDN)GM3 in sperm.

Animals↗

PubMed1993

Pulsatility index of uterine artery in pregnant and non-pregnant women.

In 60 infertile women, 73 uterine arterial pulsatility indices (PI) were measured by transvaginal colour Doppler sonography. The aims were to assess uterine perfusion response in infertile women during spontaneous ovarian cycles, and to analyse the change of uterine perfusion in pregnant cases. The mean PI values (+/- SD) of 67 non-pregnant cycles were 2.30 (+/- 0.78) in the follicular phase, 2.51 (+/- 1.05) in the ovulatory phase and 2.50 (+/- 0.97) in the mid-luteal phase. The mean PI values (+/- SD) of six pregnant cycles were 1.67 (+/- 0.22), 1.89 (+/- 0.41) and 2.23 (+/- 0.69) in the corresponding phases respectively. The difference between the PI values in the follicular phase for the pregnant and non-pregnant groups was significant (P < 0.05), as well as that between the follicular and mid-luteal phase for the pregnant group (P < 0.05). There was no significant difference between the PI values in the ovulatory or mid-luteal phase of the two groups.

Arteries↗

PubMed1993

Well-developed infant with hypoxic-ischemic encephalopathy associated with EEG burst suppression and subcortical leukohypodensity on CT scan.

In the prediction of neurological sequelae after hypoxic-ischemic encephalopathy (HIE) in the newborn, the electroencephalogram (EEG) burst suppression pattern (BS) and subcortical leukomalacia can mean grave neurodevelopmental problems will develop. This study presents an infant with HIE associated with BS and subcortical leukohypodensity (SLH) on computed tomography scan. At first her neurodevelopmental outcome was considered poor, but unexpectedly she showed good development in 32 months follow-up. The findings of BS and SLH do not always result in a poor neurodevelopmental outcome, if the subsequent clinical state and EEG return to normal at an early stage.

Brain Ischemia↗

PubMed1993

Plateau pattern of afferent discharge rate from frog muscle spindles.

1. A characteristic plateau pattern was observed in the rate of afferent discharges during ramp-and-hold stretch of spindles isolated from semitendinosus muscles of frogs. The plateau pattern was more frequent in summer frogs (84%) than winter frogs (11%). 2. The plateau pattern consisted of a discharge rate around 120 imp/s at the end of dynamic stretch, followed by second and third steps of plateau rates around 60 and 40 imp/s, respectively. The intervals of impulses in lower steps were approximately n times those of the top step. 3. The plateau pattern was not sensitive to cutting extracapsular myelinated branches or lowering temperature from 23 to 12 degrees C. However, the number of the plateau was reduced in both cases. 4. Application of depolarizing current to the sensory terminal abolished the plateau pattern. In contrast, in spindles that did not show a plateau pattern, hyperpolarizing current induced such a pattern. 5. Calcium channel blockers and protein kinase C inhibitors abolished the plateau pattern. The plateau pattern could be established in quiescent spindles by drugs eliciting Ca2+ entry, raising cytosolic-free Ca2+, and activating protein kinase C. 6. The most striking aspect of the present study is the stability in the discharge rate at each step of the plateau, irrespective of different experimental conditions. This suggests that the spindle sensory terminal possesses a stable intrinsic rhythm generator in excitation, of which maximum frequency is 120 imp/s. The generator seems to be triggered by stretch stimulus and to be regulated by cytoplasmic Ca2+ and protein kinase C.

Afferent Pathways↗

PubMed1993

Distribution of fluoride in human dental calculus.

The distribution of fluoride in human dental calculus was investigated using a mechanical sampling technique and the fluoride electrode. The fluoride concentrations were highest at the outer surface of dental calculus and, then fell to a plateau for the interior of the calculus, rising again as the tooth surface was approached. The coefficient of variation of fluoride concentration was significantly greater in the sub- than in the supragingival calculus (p < 0.01). The supragingival calculus thus tended to show a smoother distribution profile for fluoride than the subgingival calculus. Total fluoride, average fluoride, and maximum fluoride concentrations were not significantly different in supra- and subgingival calculus. No significant different were observed between males and females.

Adult↗

PubMed1993

[Immunological study on Alzheimer's disease using anti-beta-protein monoclonal antibodies].

Monoclonal antibodies (TB1 & TB2), which were obtained by immunization of 24 amino acids in BALB/c mice, bound specifically to the amyloid senile plaque and amyloid-angiopathic lesions of brain tissues of patients with Alzheimer's disease (AD) or with senile dementia of Alzheimer type (SDAT), and strongly reacted with the 1st part (Asp-Ala-Glu-Phe-Arg-His-Asp) of beta-protein. Western blotting and two-dimensional immunoelectrophoresis of cerebrospinal fluid (CSF) and serum revealed bands of 125 and 20 kilodaltons. The positive frequency of 125 and 20 KD bands detected by two-dimensional immunoelectrophoresis was higher in the serum of AD and SDAT patients (12 cases) than in that of normal control patients. ELISA employing various anti-amyloid precursor protein (APP) antibodies was performed using the extract of the human neuroblastoma cell line (NB39) which produces APP. In the near future, we hope to measure APP in CSF and sera from patients with Alzheimer's disease.

Aged↗

PubMed1993

Dynamic control of cell-cell adhesion for multicellular organization.

Cadherin cell-cell adhesion molecules are associated with cytoskeletal proteins, including alpha and beta catenin, and plakoglobin. This cadherin-catenin complex plays an indispensable role in construction of ordered multicellular structures such as polarized epithelium. alpha-catenin is crucial for the cell binding function of cadherins; without it, cells cannot use the cadherin adhesion system for their adhesion. beta-catenin and plakoglobin possibly play more regulatory roles, as it was shown that their tyrosine phosphorylation correlated with modified cadherin activities. The expression of some cadherin-associated proteins is controlled by the wingless/Wnt-1 signal in embryos. These regulatory mechanisms of cadherin function and expression may be involved in dynamic control of cell-cell contacts during morphogenesis, and even in certain processes of cell growth and differentiation.

Animals↗

PubMed1993

Bellini's duct tumor associated with end stage renal disease: a case diagnosed by lectin immunohistochemistry.

We report a hemodialysis patient with an atypical renal neoplasm. The tumor cells were arranged in a two-cell pattern similar to that in the usual excretory duct systems. The histochemical staining pattern with some lectins and monoclonal antibody corresponded to the distal nephrons of normal kidney tissue. These findings enabled us to diagnose this patient as having so-called Bellini's duct tumor.

Carcinoma, Intraductal, Noninfiltrating↗

PubMed1993

[SPECT (single photon emission computed tomography) findings in 4 cases of neuronal migration disorders].

We report SPECT findings in four children with various types of neuronal migration disorders. SPECT of a patient with heterotopia showed a protrudent abnormal shadow into the centrum semiovale, the density of which was same as that of normal gray matter. The function and the metabolism of heterotopia appear same as those of the normal gray matter. SPECT of a patient with pachygyria showed decreased blood flow in the areas of thickened cortex. This finding seems to indicate hypofunction of those lesions. SPECT of a patient with hemimegalencephaly showed an increased blood flow in the ipsilateral hemisphere and decreased blood flow in the contra-lateral hemisphere. In the literature, increased contents of neuronal elements in the affected site and arterio-venous shunt with cardiac failure have been reported in hemimegalencephaly. These pathologies may be related to our SPECT findings. SPECT of a patient with cortical dysplasia showed extensive lesions of decreased blood flow which was more wide spread than abnormal lesions detected by MRI. SPECT may be more sensitive than MRI to detect cortical dysplasias.

Adolescent↗

PubMed1992

Purification and characterization of a sialidase from Bacteroides fragilis SBT3182.

A sialidase from Bacteroides fragilis SBT3182 was purified 2,240-fold to apparent homogeneity by ammonium sulfate precipitation and sequential chromatographies on DEAE-Toyopearl 650M, Hydroxyapatite, MonoS and Superose6 columns. The N-terminal amino acid sequence of this sialidase, Ala-Asp-X-Ile-Phe-Val-Arg-Glu-Thr-Arg-Ile-Pro-, was determined. Substrate specificity of this enzyme using a variety of sialoglycoconjugates showed a 1.5- and 2.2-fold preference for sialyl alpha 2-8 linkages when compared with alpha 2-3 and alpha 2-6 bound sialic acids, respectively. The native sialidase had a molecular weight of 165kDa, as determined by Superose6 gel filtration chromatography and consisted of three subunits each of 55kDa by SDS-polyacrylamide gel electrophoresis. This enzyme had optimal activity at pH6.1 with colominic acid as substrate.

Amino Acid Sequence↗

PubMed1992

Structure of the bovine ETB endothelin receptor gene.

The structure of the gene encoding the bovine type B endothelin receptor (ETB) has been established and compared with those of other heptahelical receptors. The gene is present as a single copy in the bovine genome, as demonstrated by Southern blot analysis, and spans at least 36 kb. The coding region is divided into 7 exons separated by 6 introns, one of which is more than 23 kb in length. The exons correspond well to the structural domains of the receptor: the first exon encodes the first and second transmembrane domains, and each of the following transmembrane domains is encoded by a separate exon. The portion of the ETB protein sequence encoded by exon 3 is quite different from the corresponding ETA sequence, suggesting that this region is responsible for the distinct ligand specificities of the two receptor subtypes. The second intron interrupts the canonical Asp-Arg-Tyr sequence, which is located at the end of the third transmembrane domain of the heptahelical receptors, as with the substance P, substance K, dopamine D2 and dopamine D3 receptor genes. To map the 5' region of the gene and determine the start of transcription, primer-extended cDNAs were cloned and sequenced: multiple start sites were deduced with no apparent TATA box in the expected upstream region. Similar results were obtained by ribonuclease protection analysis.

Animals↗

PubMed1992

Primary structure of the human elafin precursor preproelafin deduced from the nucleotide sequence of its gene and the presence of unique repetitive sequences in the prosegment.

The human elafin gene was cloned and its entire nucleotide sequence was determined to deduce the amino acid sequence for the precursor of elafin, an elastase-specific inhibitor. The gene spans approximately 1.7 kb and is divided into 3 exons. The gene product preproelafin consists of 117 amino acids: the initiator Met, a putative 25-amino acid signal peptide, a pro-sequence of about 34 amino acids, and the C-terminal 57 amino acids for mature elafin. Possible covalent clotting of the prosegment and its physiological significance have been pointed out based on a remarkable sequence similarity between the pro-sequence and the guinea pig seminal clotting protein SVP-1.

Amino Acid Sequence↗

PubMed1992

The thickness of the sound and periodontally diseased human cementum.

Cementum of teeth previously analysed for fluoride was re-examined in order to determine whether or not periodontal disease had affected the thickness of the tissue. In the periodontally diseased teeth the cementum was thinner than normal in the middle region of the root. The apical cementum, however, was significantly thicker in periodontally diseased than in the sound teeth of subjects over 60 yr old. This may account for the higher total fluoride levels previously reported in the apical cementum of these same teeth.

Adult↗

PubMed1992

Liposomal modification with uronate, which endows liposomes with long circulation in vivo, reduces the uptake of liposomes by J774 cells in vitro.

For overcoming rapid removal of liposomes from the bloodstream, we developed reticuloendothelial system (RES)-avoiding liposomes modified with a uronic acid derivative, palmityl-D-glucuronide (PGlcUA). In this current study, we examined the in vitro interaction of PGlcUA-liposomes with J774 cells derived from mouse macrophages. Liposomal association with J774 cells at 37 degrees C did not increase compared with the binding at 4 degrees C when liposomes were modified with PGlcUA. RES-avoiding ability was not specifically endowed by glucuronate but by uronates in general, since palmityl-D-galacturonide showed a similar effect on liposomal clearance in vivo and liposomal uptake in vitro. These facts indicate that modification of the liposomal surface with uronic acid derivatives endows liposomes with a long circulation time in the bloodstream by reducing their uptake by macrophages.

Animals↗

PubMed1992

Transient, unilateral, isolated hypoglossal nerve palsy.

We report a boy with isolated hypoglossal nerve palsy that recovered within twelve weeks. Investigations of the cervix, base of the skull, medulla and hypoglossal nerve by CT-scan and MRI did not show any abnormal findings. There are a few reports concerning isolated unilateral hypoglossal nerve palsy with benign course. Although we could not establish the cause of our patient's disease, an awareness of this condition should save such patients from unnecessary invasive studies.

Child↗

PubMed1992

[Clinical studies on pediatric purulent meningitis--clinical symptoms and prognosis].

In 149 patients with purulent meningitis we encountered in the period of 20 years from 1970 to 1990, their clinical symptoms and prognosis were investigated. Death or sequela was noted in many of the patients having loss of consciousness, stiffness of the members and/or cyanosis as primary clinical symptoms, or having hypoalbuminemia (less than 2.5 g/dl) and/or thrombocytopenia as abnormal laboratory findings, or having excessive protein levels and/or excessively low sugar levels in cerebro-spinal fluid. Early initiation of adequate antibiotic therapy, as well as symptomatic treatment using transfusion, steroids and anticonvulsants, are important.

Female↗

PubMed1992

[Clinical studies on pediatric purulent meningitis--statistical analysis of etiology and therapy].

In a total of 149 children with purulent meningitis we encountered in our institute in the last 20 years, the causatives, the changes in therapeutic management and the prognosis were investigated. The causatives could be detected in 109 patients (73%): H. influenzae; 30 patients (20%), S. pneumoniae; 18 patients (12%), E. coli; 13 patients (9%), GBS; 7 patients (5%) and S. aureus; 6 patients (4%). These five causatives were detected in 49% of the total patients, or 67% of the patients in whom causatives could be detected. Of these five causatives, E. coli were detected the most frequently in the first half of 1970's, but, in recent years, the detection of GBS, S. pneumoniae and H. influenzae has been remarkably increasing. In spite of progress in antibiotics, the prognosis of the disease due to S. pneumoniae, GBS and S. aureus was poor. In the majority of the patients who died, the death came within five days after hospitalization due to loss of consciousness, convulsion etc. It is therefore necessary not only to initiate strong antibiotic treatment as soon as possible after early diagnosis, but also to take symptomatic measures such as steroidal treatment, treatment of shock etc.

Anti-Bacterial Agents↗