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Biomedical subjects

I Tanaka

Publications and source records attributed to I Tanaka.

At least 307 records · Page 17Linked to original sources
PubMed1993

Location and axonal projection of early-onset decrementing expiratory neurons in the cat.

The location and axonal projection of early-onset decrementing expiratory (eE-DEC) neurons were studied in Nembutal-anesthetized, paralyzed, and artificially ventilated cats. The eE-DEC neurons started firing around the peak of phrenic activity and attained maximum firing at the transition from inspiration to expiration. The eE-DEC neurons were distributed in the dorsomedial border of the dense assembly of respiratory neurons of the ventral respiratory group and the Bötzinger complex. Antidromic microstimulation showed that the eE-DEC neurons projected mainly to the ipsilateral reticular formation medial and dorsal to the nucleus ambiguus at the level of the obex but rarely to the medullary respiration-related areas. Participation of these eE-DEC neurons in the inspiratory off-switch may not be possible.

Animals↗
PubMed1993

Crystal structures of ribonuclease HI active site mutants from Escherichia coli.

In order to investigate the relationships between the three-dimensional structure and the enzymic activity of E. coli RNase HI, three mutant proteins, which were completely inactivated by the replacements of three functional residues, Asp10 by Asn (D10N), Glu48 by Gln (E48Q), and Asp70 by Asn (D70N), were crystallized. Their three-dimensional structures were determined by x-ray crystallography. Although the entire backbone structures of these mutants were not affected by the replacements, very localized conformational changes were observed around the Mg(2+)-binding site. The substitution of an amide group for a negatively charged carboxyl group in common induces the formation of new hydrogen bond networks, presumably due to the cancellation of repulsive forces between carboxyl side chains with negative charges. These conformational changes can account for the loss of the enzymic activity in the mutants, and suggest a possible role for Mg2+ in the hydrolysis. Since the 3 replaced acidic residues are completely conserved in sequences of reverse transcriptases from retroviruses, including human immunodeficiency virus, the concepts of the catalytic mechanism deduced from this structural analysis can also be applied to RNase H activity in reverse transcriptases.

Binding Sites↗
PubMed1993

Clinical importance of CD7 expression in acute myelocytic leukemia. The Japan Cooperative Group of Leukemia/Lymphoma.

Forty patients (9 females and 31 males; mean age 41.9 years) with CD7+ acute myelocytic leukemia (AML) were investigated; they were classified into the following subgroups according to French-American-British classification: 15 M1, 18 M2, 3 M4, and 4 M5. Leukemic cells from all the patients were negative for T-cell-specific antigens, surface CD3, and T-cell-receptor molecules. The sex and age distributions were different from those of CD7- AML patients (P < .01). Hepatomegaly and central nervous system involvement were also frequent in the CD7+ AML patients. The phenotype of and responsiveness to hematopoietic growth factors by the leukemic cells showed their immaturity, as evidenced by frequent expression of CD34, HLA-DR, and TdT, and the greatest growth response to interleukin-3. No particular karyotypic abnormality was shown. One hundred eighty AML patients were treated with a therapeutic regimen routinely used for AML. The CD7+ AML patients showed a significantly lower response than CD7- AML patients (P < .01), and had a poorer prognosis (P < .01). CD7+ AML patients with M1 or M5b had unfavorable responses to the therapeutic regimen in comparison with patients with M2, M4, or M5a. In addition, 3 of 4 CD7+ CD2+ AML patients, who did not respond to the therapy, were induced into complete remission with an acute lymphoblastic leukemia therapy. The results presented here indicate the diagnostic importance of CD7 positivity in AML, suggesting that the cellular and clinical characteristics of CD7+ AML are sufficient for it to be recognized as a distinct category of AML.

Adolescent↗
PubMed1993

[Neurotoxicity of methyl bromide--neuropathologic evaluation--preliminary study].

Methyl bromide exposure produces disorders of the central and peripheral nervous system. In the literature, there are many neuropathologic studies on the nervous system, especially on the central nervous system, of experimental animals intoxicated with methyl bromide presented. However, in our opinion, a variety of lesions of the nervous system described in the human methyl bromide intoxication have not been well reproduced in the experimental animals. In this study, male Wistar rats were subjected to a 6-hour exposure a day to methyl bromide at a concentration of 500 or 290 ppm 3 days a week for 3 to 8 weeks. The systematic neuropathologic studies of their central and peripheral nervous systems were carried out to reproduce the nervous system lesions in the human methyl bromide intoxication hitherto not produced in the experimental animals. Among the rats exposed to methyl bromide at a concentration of 500 ppm for 10 to 18 days, the axonal degeneration of myelinated fibers at the cervical level of the fasciculus gracilis, which probably corresponds to the degeneration of the spinal posterior column in humans, and the necrosis of the caudate-putamen and atrophy of neurons and pallor of the neuropile in caudate-putamen, thalamus and cingulate cortex, which probably correspond to the degenerative findings of the cerebrum in humans, were found. The rats exposed to methyl bromide at a concentration of 290 ppm for 8 weeks (24 days) did not show any noticeable abnormalities histologically.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

A factor VIII neutralizing monoclonal antibody and a human inhibitor alloantibody recognizing epitopes in the C2 domain inhibit factor VIII binding to von Willebrand factor and to phosphatidylserine.

A neutralizing monoclonal antibody, NMC-VIII/5, recognizing the 72 kDa thrombin-proteolytic fragment of factor VIII light chain was obtained. Binding of the antibody to immobilized factor VIII (FVIII) was completely blocked by a light chain-specific human alloantibody, TK, which inhibits FVIII activity. Immunoblotting analysis with a panel of recombinant protein fragments of the C2 domain deleted from the amino-terminal or the carboxy-terminal ends demonstrated binding of NMC-VIII/5 to an epitope located between amino acid residues 2170 and 2327. On the other hand, the epitope of the inhibitor alloantibody, TK, was localized to 64 amino acid residues from 2248 to 2312 using the same recombinant fragments. NMC-VIII/5 and TK inhibited FVIII binding to immobilized von Willebrand factor (vWF). The IC50 of NMC-VIII/5 for the inhibition of binding to vWF was 0.23 micrograms/ml for IgG and 0.2 micrograms/ml for F(ab)'2. This concentration was 100-fold lower than that of a monoclonal antibody NMC-VIII/10 which recognizes the amino acid residues 1675 to 1684 within the amino-terminal portion of the light chain. The IC50 of TK was 11 micrograms/ml by IgG and 6.3 micrograms/ml by F(ab)'2. Furthermore, NMC-VIII/5 and TK also inhibited FVIII binding to immobilized phosphatidylserine. The IC50 for inhibition of phospholipid binding of NMC-VIII/5 and TK (anti-FVIII inhibitor titer of 300 Bethesda units/mg of IgG) was 10 micrograms/ml.

Antibodies, Monoclonal↗
PubMed1993

Bacteriological investigation of bile in patients with cholelithiasis.

The microflora in bile from the gallbladder and common bile duct was investigated in 303 patients who underwent surgery for cholelithiasis. The purpose of this study was to identify current bacteria and bacterial casts in the biliary tract and also to analyze the relationship between bactericholia at the time of operation and postoperative infection. Bile cultures were positive in 38% of all patients, although a higher incidence of positive bile cultures occurred in patients over 70 years of age (77%), those with common duct stones (83%), those with pigment stones (65%), and those who underwent gastrectomy (71%). The predominant organisms were Escherichia coli (22%), Klebsiella (18%), and Enterococcus (15%). Obligate anaerobes were less frequently seen (4%), being found only in patients with pigment stones and always mixed with aerobes. Four patients developed postoperative infections (1.3%) which were all caused by biliary bacteria. The following two factors may contribute to this low incidence of postoperative infections: our policy of operating electively whenever possible, and the prophylactic use of antibiotics to which the organisms cultured from bile are sensitive.

Adult↗
PubMed1993

Lumbar artery pseudoaneurysm: an unusual cause of a retroperitoneal hematoma: report of a case.

Pseudoaneurysm of the lumbar artery is a rare complication of penetrating trauma. We present herein a case thought to have been caused by a blow to the left flank without any evidence of a stab wound. In this patient, the diagnosis of a first lumbar artery pseudoaneurysm with a retroperitoneal hematoma was confirmed by computed tomography (CT) findings, after which transcatheter embolization was successfully performed.

Aneurysm↗
PubMed1993

Solubility of nickel oxide particles in various solutions and rat alveolar macrophages.

The solubility of five types of commercial nickel oxide particles was determined in different types of solutions, including distilled water, physiological saline, buffered saline, and tissue-culture medium, in order to estimate their solubility in the human respiratory tract. In addition, we examined the solubility of the two types of particles that were the most and least soluble particles of the above five types of nickel oxide, in rat alveolar macrophages cultured in vitro. The solubility of the nickel oxide particles in these solutions varied remarkably with their types, suggesting that, even though they are called as "nickel oxide," their solubilities are different among the manufacturer and the product lot. Their solubilities were also influenced by the types of solution and the existence of carbon dioxide in the atmosphere. The solubility of nickel oxide particles in the alveolar macrophages was significantly larger than that observed in the culture medium without macrophages, but smaller than that observed in the distilled water. These results suggest that the actual solubility of nickel oxide particles in the respiratory tract may be difficult to estimate by the conventional solubility analysis method using distilled water, and that the enhancement of particle dissolution by the alveolar macrophages and the depression of particle solubility by the coexisting salt and carbon dioxide should be taken into consideration for the accurate estimation.

Animals↗
PubMed1993

Interleukin-2 receptor alpha chain on acute myelocytic leukemia cells is involved in cell-to-cell interactions.

Leukemic cells from 21 to 197 adult patients with de novo acute myelocytic leukemia (AML) were positive for IL-2R alpha chain (IL-2R alpha), whereas IL-2R beta chain (IL-2R beta), which is responsible for IL-2 signal transduction, was not found on leukemic cells from any of these cases tested. The expression of IL-2R alpha was closely associated with that of adhesion molecules CD4, CD11b and CD22, and endopeptidase CD10. None of the IL-2R alpha (+) AML cells responded to recombinant human IL-2. These data suggest that IL-2R alpha on AML cells may not be involved in cellular proliferation as one of growth factor receptors but may have a role in the control of cell-to-cell interactions.

Adult↗
PubMed1993

Synergistic effects of mineral fibres and cigarette smoke on the production of tumour necrosis factor by alveolar macrophages of rats.

The objective of this study was to evaluate the combined effects of mineral fibres and cigarette smoke on the production of tumour necrosis factor (TNF) by alveolar macrophages. Rats were exposed to cigarette smoke in vivo, and production of TNF by alveolar macrophages was measured in the presence of mineral fibres in vitro. For smoke exposure, rats were divided into two groups. Five were exposed to a daily concentration of 10 mg/m3 of cigarette smoke for an eight hour period, and five rats (controls) were not exposed to smoke. Bronchoalveolar lavage was performed after exposure to smoke and the recovered alveolar macrophages were incubated with either chrysotile or ceramic fibres on a microplate for 24 hours. Activity of TNF in the supernatant was determined by the L-929 fibroblast cell bioassay. When alveolar macrophages were not stimulated by mineral fibres, production of TNF by rats exposed to smoke and unexposed rats was essentially the same. When alveolar macrophages were stimulated in vitro by chrysotile or ceramic fibres, production of TNF by alveolar macrophages from rats exposed to smoke was higher than that by alveolar macrophages from unexposed rats. The findings suggest that cigarette smoke and mineral fibres have a synergistic effect on TNF production by alveolar macrophages.

Aluminum Silicates↗
PubMed1993

[A simultaneous determination of honokiol and mangolol in Oriental pharmaceutical decoctions containing magnolia bark by ion-pair high-performance liquid chromatography. II].

A simple method using ion-pair high-performance liquid chromatography was established for the rapid and precise determination of honokiol(3',5-di-2-propenyl-1,1'-biphenyl-2,4'-diol) and magnolol(5,5'-di-2-propenyl-1,1'-biphenyl-2,2'-diol) in eighteen species of oriental pharmaceutical decoctions containing Magnolia bark. An ODS column and a mixed solvent system of water involving 10 mM tetra-n-amyl-ammonium bromide (TAA) and acetonitrile (4:6) as a mobile phase were used for the separation. Honokiol and magnolol were eluted without interference of other coexisting components within 12 min.

Biphenyl Compounds↗
PubMed1993

Testosterone normalizes plasma vasopressin response to osmotic stimuli in men with hypogonadism.

We studied plasma vasopressin concentrations during hypertonic saline infusions in 5 men with hypogonadism and 10 normal men to investigate the effect of gonadal steroid on hypothalamo-neurohypophyseal function. All the subjects received the infusion of 5% saline, and plasma vasopressin concentrations were determined by radioimmunoassay (RIA). Three of the 5 men were patients with isolated hypogonadotropic hypogonadism (IHH) and the other two were patients with Klinefelter's syndrome. None of them had any symptoms of diabetes insipidus. Although there was no difference between basal plasma osmolality in the patients and the normal subjects (287.2 +/- 2.1 vs. 285.3 +/- 1.8 mmol/kg), the basal level of plasma vasopressin in the patients was lower than that in the normal subjects (0.62 +/- 0.17 vs. 1.36 +/- 0.15 pg/ml, P < 0.05). Hypertonic saline infusion revealed varying degrees of subnormal vasopressin responses in the patients except one patient with Klinefelter's syndrome. The mean vasopressin response to osmotic stimuli (delta plasma vasopressin/delta plasma osmolality) in the 5 patients was lower than in the normal subjects (0.04 +/- 0.01 vs. 0.16 +/- 0.02, P < 0.05). Three patients with IHH and one patient with Klinefelter's syndrome were re-examined after pulsatile gonadotropin-releasing hormone (GnRH) infusion or testosterone enanthate i.m. injection. After the treatment with testosterone or GnRH, the response of plasma vasopressin to hypertonic saline infusion was normalized in three patients who had subnormal vasopressin response before treatment (delta plasma vasopressin/delta plasma osmolality: 0.04 +/- 0.01 vs. 0.09 +/- 0.01, P < 0.05). These results suggest that testosterone improves the subnormal vasopressin response to osmotic stimuli in men with hypogonadism.

Adolescent↗