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Biomedical subjects

Y Higuchi

Publications and source records attributed to Y Higuchi.

At least 73 records · Page 4Linked to original sources
PubMed2000

[A case of retroperitoneal schwannoma: diagnostic usefulness of magnetic resonance imaging].

A 36-year-old man visited our hospital with a chief complaint of difficult urination. He was admitted for further examination because ultrasonography showed a heterogeneous solid mass in the lower abdomen. Intravenous urography showed the right ureter and bladder to be pushed leftward without hydronephrosis. Computerized tomography showed a giant solid mass in the retrovesical space. Magnetic resonance imaging revealed a round, well-encapsulated tumor, showing low intensity on the T1-weighted image, heterogeneously high intensity on the T2-weighted image and irregular enhancement with Gd-DTPA. Histopathology of the extirpated tumor was benign schwannoma.

Adult↗
PubMed2000

Thrombopoietin enhances neutrophil production by bone marrow hematopoietic progenitors with the aid of stem cell factor in congenital neutropenia.

We examined the effects of granulocyte colony-stimulating factor (G-CSF), stem cell factor (SCF), and thrombopoietin (TPO), alone or in combination, on the generation of neutrophils by bone marrow (BM) cells from three patients with severe congenital neutropenia (SCN) through the use of a serum-deprived liquid culture system. Synergistic effects of G-CSF and SCF on the neutrophil production by BM CD34+CD38+c-kit+ cells were observed in SCN patients as well as in normal controls. The addition of TPO to the culture containing G-CSF and SCF further augmented the growth of neutrophils in the two groups. Single-cell culture experiments revealed that the three-factor combination caused increases in both the number and size of neutrophil colonies compared with G-CSF + SCF in normal BM cells, whereas only a significant increment in the colony size was observed in SCN patients. Even in the presence of SCF or SCF + TPO, the concentrations of G-CSF necessary for the substantial production of neutrophils by CD34+CD38+c-kit+ cells were higher in two patients compared with the levels obtained by normal control cells. In addition, TPO did not accelerate the maturation of neutrophilic cells supported by G-CSF + SCF. When BM CD34+CD38-c-kit+ cells were targeted, the addition of TPO to the culture containing G-CSF and SCF was required for significant neutrophil colony growth in the two groups. These results suggest that TPO enhances the G-CSF-dependent neutrophil production with the aid of SCF in this disorder.

ADP-ribosyl Cyclase↗
PubMed1999

Quantitative determination of arterial wall mechanics with pulse oximetric finger plethysmography.

PURPOSE: The plethysmographic wave of pulse oximetry reflects arterial pulsation at the fingertip. Since arterial pressure and the pulsatile component of the arterial cross section represent the input and output of the fingertip arterial system, respectively, arterial wall mechanics may be delineated from their relationship. We aimed to construct a mathematical model of the fingertip arterial wall from the relationship between the plethysmographic wave and arterial pressure. METHODS: The pulse oximetric plethysmographic signal at the forefinger and pressure at the ipsilateral radial artery were measured. Employing the data, simple mathematical models with one to four mechanical elements were tested in terms of the goodness of fit and the physiological implications. The determined model was applied to the data obtained during administration of vasoactive agents in anesthetized patients. RESULTS: The mathematical model suited for describing arterial wall mechanics was a four-element, two-compartment model. The two compartments represent passive mechanical and active contractile properties, respectively. In the application of the model to the anesthetized patients, the vasoactive agents produced changes in the model parameters that implied mechanical alterations in the arterial wall. CONCLUSION: These findings suggest the benefit of the four-element, two-compartment model in analyzing peripheral vascular wall mechanics influenced by various stimuli in intensive care and anesthesia.

Journal Article↗
PubMed1999

Crystal structure of chitosanase from Bacillus circulans MH-K1 at 1.6-A resolution and its substrate recognition mechanism.

Chitosanase from Bacillus circulans MH-K1 is a 29-kDa extracellular protein composed of 259 amino acids. The crystal structure of chitosanase from B. circulans MH-K1 has been determined by multiwavelength anomalous diffraction method and refined to crystallographic R = 19.2% (R(free) = 23.5%) for the diffraction data at 1.6-A resolution collected by synchrotron radiation. The enzyme has two globular upper and lower domains, which generate the active site cleft for the substrate binding. The overall molecular folding is similar to chitosanase from Streptomyces sp. N174, although there is only 20% identity at the amino acid sequence level between both chitosanases. However, there are three regions in which the topology is remarkably different. In addition, the disulfide bridge between Cys(50) and Cys(124) joins the beta1 strand and the alpha7 helix, which is not conserved among other chitosanases. The orientation of two backbone helices, which connect the two domains, is also different and is responsible for the differences in size and shape of the active site cleft in these two chitosanases. This structural difference in the active site cleft is the reason why the enzymes specifically recognize different substrates and catalyze different types of chitosan degradation.

Amino Acid Sequence↗
PubMed1999

Crystal structure of a prokaryotic replication initiator protein bound to DNA at 2.6 A resolution.

The initiator protein (RepE) of F factor, a plasmid involved in sexual conjugation in Escherichia coli, has dual functions during the initiation of DNA replication which are determined by whether it exists as a dimer or as a monomer. A RepE monomer functions as a replication initiator, but a RepE dimer functions as an autogenous repressor. We have solved the crystal structure of the RepE monomer bound to an iteron DNA sequence of the replication origin of plasmid F. The RepE monomer consists of topologically similar N- and C-terminal domains related to each other by internal pseudo 2-fold symmetry, despite the lack of amino acid similarities between the domains. Both domains bind to the two major grooves of the iteron (19 bp) with different binding affinities. The C-terminal domain plays the leading role in this binding, while the N-terminal domain has an additional role in RepE dimerization. The structure also suggests that superhelical DNA induced at the origin of plasmid F by four RepEs and one HU dimer has an essential role in the initiation of DNA replication.

Amino Acid Sequence↗
PubMed1999

Suppression of FRP-1/CD98-mediated multinucleated giant cell and osteoclast formation by an anti-FRP-1/CD98 mAb, HBJ 127, that inhibits c-src expression.

When anti-CD98 mAb 6-1-13, 4-5-1, or 38-2-2 was added to the culture fluids of monocytes, extensive cell aggregation and polykaryocyte formation were induced. These multinucleated giant cells were tartrate-resistant acid phosphatase (TRAP) positive. On the other hand, when monocytes were incubated with another anti-CD98 mAb, HBJ 127, polykaryocyte formation was not detected, although extensive cell aggregation was induced. When HBJ 127 and 6-1-13 were simultaneously added to the culture fluids, anti-CD98 mAb-induced cell fusion was inhibited almost completely. HBJ 127 suppressed formation of 6-1-13-induced cell fusion in a dose-dependent manner. If, however, HBJ 127 was added after incubation of monocytes with mAb 6-1-13 for 6 h, an appreciable degree of TRAP-positive polykaryocyte formation was found. The bindings of 6-1-13 and HBJ 127 were not mutually competed. When monocytes were incubated with 6-1-13 or HBJ 127, 6-1-13 induced c-src mRNA, while HBJ 127 did not. Furthermore, when monocytes were incubated with both 6-1-13 and HBJ 127, c-src mRNA could not be detected, showing that HBJ 127 suppresses c-src expression. Therefore, CD98-mediated osteoclast formation can be regulated by modification of CD98 system.

Antibodies, Monoclonal↗
PubMed1999

Glutathione depletion induces giant DNA and high-molecular-weight DNA fragmentation associated with apoptosis through lipid peroxidation and protein kinase C activation in C6 glioma cells.

Glutathione (GSH) depletion caused by l-buthionine-(S,R)-sulfoximine (BSO) induced apoptosis that was recognized by terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick endo-labeling (TUNEL), nuclear DNA staining with fluorescence dye, and internucleosomal DNA fragmentation in C6 rat glioma cells. The BSO-induced cell death was associated with caspase-3 activation. Lipid peroxidation and protein kinase C (PK-C) activation were observed during the apoptosis of C6 cells, and these events were inhibited by antioxidants and iron chelators without affecting BSO-induced GSH depletion. Furthermore, approximately 2 Mbp giant DNA fragments were observed in the BSO-treated cells. The giant DNA fragmentation were followed by approximately 30-700 kbp and then less than 100 kbp, including internucleosomal DNA fragmentations. Such serial DNA degradation was prevented by the antioxidants, the iron chelators, and the PK-C inhibitors. These results suggest that during apoptosis induced by GSH-depletion caused by BSO, reactive oxygen species endogenously produced cause lipid peroxidation and that the lipid peroxidation induced PK-C activation, processes which are thought to be involved in the giant DNA, high-molecular-weight DNA, and the internucleosomal DNA fragmentations.

Animals↗
PubMed1999

Liberation of hydrogen sulfide during the catalytic action of Desulfovibrio hydrogenase under the atmosphere of hydrogen.

The active site of [NiFe] hydrogenase from Desulfovibrio species is composed of a binuclear Ni-Fe complex bearing three diatomic nonprotein ligands to Fe and three bridges between the two metals, two of which are thiolate side chains of the protein moiety. The third bridging atom in the enzyme isolated from D. vulgaris Miyazaki F was suggested to be sulfur species, but was suggested to be oxygen species in D. gigas enzyme. When the hydrogenase from D. vulgaris Miyazaki F was incubated under the atmosphere of H2, H2S was liberated from the enzyme only in the presence of its electron carrier, cytochrome c3 or methylviologen. The amount of H2S liberation was little in the absence of electron carrier or essentially null when the enzyme was incubated under N2. The amount of H2S liberated was about 37% of the hydrogenase contained in the reaction vial in molar basis. These observations are in agreement with the recent observation that the third bridging site at the Ni-Fe active site is vacant in the reduced form of the enzyme revealed by X-ray crystallography.

Alcaligenes↗
PubMed1999

Ectopic bronchus: an insufficiently recognized malformation causing respiratory morbidity in VATER association.

An 11-month-old boy presented with recurrent wheezing and atelectasis in the right upper lobe of the lung. Bronchoscopy and bronchography confirmed an ectopic bronchus arising from the right main bronchus. The diagnosis of VATER association was made on the basis of multiple vertebral and rib anomalies, imperforate anus with a perineal fistula, unilateral hydronephrosis, atrial septal defect, and a preauricular tag, he did not have tracheo-esophageal fistula. We emphasize the importance of recognizing tracheobronchial anomalies in VATER association.

Abnormalities, Multiple↗
PubMed1999

Osteoporosis in hemiplegic stroke patients as studied with dual-energy X-ray absorptiometry.

OBJECTIVES: To compare bone mineral densities (BMDs) of the affected and unaffected limbs in stroke patients at multiple sites; to study longitudinal changes during a 3-month rehabilitation program; and to relate BMDs to demographic, impairment, and disability variables. DESIGN: Descriptive study. SETTING: Tertiary rehabilitation center. PATIENTS: One hundred four consecutive hemiplegic inpatients, 69 men, age 56.5 +/- 13.2 yrs, 47 with left-sided brain lesion. Median days from onset to admission and median length of stay days were 83 and 105.5, respectively. MAIN OUTCOME MEASURES: BMDs of proximal humerus, distal radius, femoral neck, and calcaneus bilaterally, and third lumbar vertebra, measured with dual-energy x-ray absorptiometry (DXA), were compared between affected and unaffected sides at admission and discharge. RESULTS: Stroke Impairment Assessment Set (SIAS) motor scores, Functional Independence Measure (FIM) scores, grip strength, and awake/sleep heart rate counts (activity index) improved significantly at discharge. Affected/unaffected BMD ratios were 88.3% to 98.4% at admission and 79.6% to 98.8% at discharge, lowest for the humerus. Discharge/admission ratios were 89.1% to 97.8% for the affected and 97.4% to 100% for the unaffected side. All BMDs were intercorrelated (R = .438 to .873). They correlated significantly with age, body weight, grip strength, FIM scores, and activity index. Factors selected to explain BMD with multiple regression analysis differed according to the site and timing of the measurement. CONCLUSIONS: BMDs of the affected side were lower and most marked in the humerus. Longitudinally, not only the affected but the unaffected BMDs decreased. Age, sex, duration of stroke, anthropometric measurements, motor paralysis, muscle strength, and activity level contributed differently to bone loss according to the site and timing of the measurement.

Absorptiometry, Photon↗
PubMed1999

ADAM family proteins in the immune system.

CD156 is a member of a family proteins characterized by a disintegrin and a metalloprotease domain (ADAM). These molecules are phylogenically conserved but have individual roles in a variety of cells. Here, Shunsuke Yamamoto and colleagues discuss data suggesting that ADAM family proteins have important roles in the immune system.

ADAM Proteins↗
PubMed1999

Congenital fiber type disproportion: severe form with marked improvement.

A 30-month-old male exhibited marked hypotonia at birth accompanied by respiratory distress necessitating ventilator support. He subsequently demonstrated marked improvement in muscle power. He became independent of the respirator at 21 days of age and was able to sit without support at 11 months and walked alone at 24 months. Histopathologic analysis of the quadriceps femoris muscle confirmed the diagnosis of congenital fiber type of disproportion at 11 months of age. No other studies have described a patient with a severe neonatal form of congenital fiber type of disproportion who demonstrated such clear improvement. Physicians should be aware of this possibility when they interact with such patients and their families.

Child, Preschool↗
PubMed1999

Removal of the bridging ligand atom at the Ni-Fe active site of [NiFe] hydrogenase upon reduction with H2, as revealed by X-ray structure analysis at 1.4 A resolution.

BACKGROUND: The active site of [NiFe] hydrogenase, a heterodimeric protein, is suggested to be a binuclear Ni-Fe complex having three diatomic ligands to the Fe atom and three bridging ligands between the Fe and Ni atoms in the oxidized form of the enzyme. Two of the bridging ligands are thiolate sidechains of cysteinyl residues of the large subunit, but the third bridging ligand was assigned as a non-protein monatomic sulfur species in Desulfovibrio vulgaris Miyazaki F hydrogenase. RESULTS: The X-ray crystal structure of the reduced form of D. vulgaris Miyazaki F [NiFe] hydrogenase has been solved at 1.4 A resolution and refined to a crystallographic R factor of 21.8%. The overall structure is very similar to that of the oxidized form, with the exception that the third monatomic bridge observed at the Ni-Fe site in the oxidized enzyme is absent, leaving this site unoccupied in the reduced form. CONCLUSIONS: The unusual ligand structure found in the oxidized form of D. vulgaris Miyazaki F [NiFe] hydrogenase was confirmed in the reduced form of the enzyme, with the exception that the electron density assigned to the monatomic sulfur bridge had almost disappeared. On the basis of this finding, as well as the observation that H2S is liberated from the oxidized enzyme under an atmosphere of H2 in the presence of its electron carrier, it was postulated that the monatomic sulfur bridge must be removed for the enzyme to be activated. A possible mechanism for the catalytic action of the hydrogenase is proposed.

Binding Sites↗
PubMed1999

Gene expression during osteoclast-like cell formation induced by antifusion regulatory protein-1/CD98/4F2 monoclonal antibodies (MAbs): c-src is selectively induced by anti-FRP-1 MAb.

Human blood monocytes can differentiate into osteoclast-like cells when they are cultured in the presence of anti-FRP-1. Messenger (mRNA) expression of markers related to osteoclasts was analyzed during differentiation of osteoclasts from monocytes. As markers related to osteoclasts, we selected cathepsin-K, carbonic anhydrase (CA) II, vacuolar H(+)-ATPase (v-ATPase), vitronectin receptor (VNR), tartrate-resistant acid phosphatase (TRAP), osteopontin (OPN), galectin-3, c-src, c-fos, and c-fms. The mRNAs other than c-src mRNA were expressed in freshly isolated monocytes or monocytes incubated with control antibody or anti-FRP-1 monoclonal antibody (MAb) for 14 days. Of these mRNAs, cathepsin-K, CA II, v-ATPase, VNR, TRAP, OPN, and c-fms mRNAs were expressed at higher levels in the osteoclast-like cells than those in monocytes cultured with control antibody. On the other hand, galectin-3 mRNA was expressed at lower levels in the osteoclast-like cells, and there was no significant difference in c-fos mRNA expression between the monocytes cultured with control antibody and anti-FRP-1 MAb. c-src mRNA could not be detected in monocytes freshly isolated or incubated with control antibody. Surprisingly, expression of c-src mRNA was induced in monocytes by anti-FRP-1 MAb and was detectable as early as 3 h after anti-FRP-1 MAb treatment, indicating that c-src is selectively induced by anti-FRP-1 MAb treatment. Furthermore, the osteoclast-like cells expressed calcitonin receptor. Receptor activator of NF-kappaB (RANK) mRNA was detectable in freshly isolated monocytes or monocytes cultured with control antibody or anti-FRP-1 MAbs. Maximal expression of RANK was observed in osteoclast-like cells. On the other hand, no receptor activator of NF-KB ligand (RANKL) mRNA was detectable in any of the samples, suggesting that anti-FRP-1 mAb can induce osteoclast-like cells from blood monocytes without RANKL.

Antibodies, Monoclonal↗
PubMed1999

Effects of sinus surgery on asthma in aspirin triad patients.

The aspirin triad (nasal polyposis, asthma and sensitivity to aspirin) is a well-recognized clinical entity, also known as aspirin-induced asthma (AIA). The sinusitis associated with AIA is often difficult to treat and aggravates the asthmatic symptoms. In order to evaluate the surgical treatment of sinusitis in AIA, 22 patients who underwent sinus surgery were studied. Twenty patients (90.9%) got any relief of their asthma symptoms from sinus surgery. Postoperative pulmonary function test 1 year after surgery showed statistically significant improvement over the preoperative one. Three of 5 patients (60%) who used systemic steroids were able to eliminate or reduce their dosages. Also, 8 of 17 patients (47.1%) who were using inhaled topical steroids reduced their dosages and statistical analysis showed a significant difference in the doses of topical steroid used before and after surgery. Subjective evaluation of 20 patients (90.9%) indicated that the sinus surgery was effective for their asthma condition; showing from mild to marked improvement. For AIA patients aggravated by sinus disease, we recommend sinus surgery to improve the quality of life.

Administration, Inhalation↗
PubMed1999

CD14 transgenic mice expressing membrane and soluble forms: comparisons of levels of cytokines and lethalities in response to lipopolysaccharide between transgenic and non-transgenic mice.

Two different metallothionein promoter-mouse CD14 fusion genes were constructed. The membrane form of the CD14 fusion gene, designated M14M, contained the full-length CD14 cDNA sequence, whereas the soluble form of the fusion gene, designated M14S, was truncated to lack the sequence for the phosphatidylinositol-anchoring site. Expression of transgenic RNA in M14M and M14S mice on the basal diet was abundant in the liver. After maintenance with water containing ZnSO4 (50 mM) for 4 days, expression of transgenic RNA in M14M and M14S mice was strong in the small intestine. Immunohistochemical analysis demonstrated CD14 expression in these organs in M14S and M14M mice. Levels of CD14 in sera from M14S mice after zinc administration were significantly higher than these animals maintained with normal water, M14M mice after zinc administration and non-transgenic mice. Sera from M14S and M14M mice after stimulation with lipopolysaccharide LPS (LPS) demonstrated significantly lower levels of tumor necrosis factor-alpha and IL-6 than those from non-transgenic mice. Lethality in endotoxin shock produced by i.p. injection of 30-40 microg/g body wt LPS was not different between M14S, M14M and non-transgenic mice. However, survival rates in the lethal Shwartzman reaction induced by priming and challenge injections of LPS were significantly higher in M14M and M14S mice than in non-transgenic mice.

Animals↗