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Biomedical subjects

M Takagi

Publications and source records attributed to M Takagi.

At least 415 records · Page 23Linked to original sources
PubMed1996

Mast cells in loosening of totally replaced hips.

This study evaluated mast cells in tissue around loose total hip implants. Interface and pseudocapsular tissues were obtained from 6 patients with a loose hip prosthesis. Mast cells were labeled with monoclonal mouse antihuman antibodies against tryptase and chymase in avidin-biotin-peroxidase complex staining and were quantitated morphometrically by means of a semiautomatic Kontron image analyzer. Almost all mast cells in situ were chymase-positive and tryptase-positive connective tissue cells. The mean number of such cells per mm2 of tissue increased in this rank order: interface (9.98 +/- 5.03 cells) < pseudocapsule (15.85 +/- 4.99 cells) < control knee synovium (25.08 +/- 8.64 cells). Mast cells in periprosthetic tissue, in contrast to normal knee synovial tissue, exhibited granule release. Mast cells around loose hip prostheses appeared to be activated by connective tissue mast cells. These were found in diminished numbers and in a degranulated state in the interface tissue between implant and bone. Mast cell activation in loco may thus lead to significant local production and/or release of proinflammatory mast cell mediators. Prevention of mast cell activation (degranulation) could prove useful in the postponement of loosening of the totally replaced hip.

Aged↗
PubMed1996

[Effects on visual functions following several hours' usage of a head mounted display].

We investigated the effects of viewing video movies with a head-mounted display (HMD) for 4 to 6 hours on visual functions such as refraction, visual acuity, and accommodation-vergence system. Two or three video movies were watched without any breaks by 13 normal volunteers (age: 22 approximately 40). Measurements were made of (1) objective and subjective refraction, (2) corrected visual acuity, (3) tonic level and step response of accommodation with a computer-assisted infrared optometer, and (4) near and far phorias and AC/A ratio. Significant transient myopia was found following 4 hours' viewing, but not following 6 hours' viewing. Scrutinizing individual data, myopia was consistently found in some subjects, and hyperopia in others. We presumed that many subjects might have been influenced by initial instrumental myopia when they adjusted the focus by using the mechanism built in the HMD. No significant change was observed in any other examination. However, there was a tendency for the AC/A ratio to change after a short time, and then to recover to its original value. Based on the results in this study, it appears that some changes in accommodation and vergence systems are caused by viewing video movies with the HMD. Although the amount of changes was within normal physiological variation in this study, the possibility still remains that usage for a longer time may lead to other changes in visual function. Care is also necessary when using the HMD in subjects with subclinical problems.

Accommodation, Ocular↗
PubMed1996

[Functional magnetic resonance imaging of the frontal eye fields during saccadic eye movements].

We evaluated activity-induced signal intensity changes in the human cerebral cortex during horizontal saccadic eye movements using functional magnetic resonance imaging (fMRI) based on the blood-oxygenation-level-dependent (BOLD) contrast method. Compared with central fixation, significant signal increases were observed bilaterally in the middle frontal gyrus (Brodmann area 8) during saccadic conditions. The location of the activated area was consistent with that of previously reported frontal eye fields (FEF). These results suggest that fMRI has potential merit for the study of cortical control of eye movements in humans.

Adult↗
PubMed1996

[Simultaneous mitral valve replacement and splenectomy in a patient with chronic idiopathic thrombocytopenic purpura].

A 57-year-old female with valvular heart disease and chronic idiopathic thrombocytopenic purpura (ITP) underwent successful open-heart surgery. Preoperative administration of steroids and high-dose gamma-globulin increased the platelet count from 3 x 10(4)/microgram at admission to 10 x 10(4)/microgram before the operation. Splenectomy followed by mitral valve replacement (SJM 27M) were performed simultaneously. No platelet transfusion needed during and after the operation owing to rapid increase in platelets that would occur following splenectomy. The postoperative course was uneventful. The present simultaneous splenectomy and open-heart operation appears to be a safe and effective procedure for minimizing perioperative blood loss in patients with ITP and heart disease.

Chronic Disease↗
PubMed1996

[Lymphomatoid granulomatosis of the brain with multiple lesions on MRI].

A 28-year-old man was admitted to our hospital, because of double vision, memory disturbance and dysarthria. These symptoms developed in November, 1994. His mental activity was gradually decreased and he became apathetic. A physical examination on admission was unremarkable. There were no lymphadenopathy, hepatosplenomegaly or skin rash. Neurological examination revealed disorientation, decreased mental activity and left gaze-evoked nystagmus. Neuropsychological tests demonstrated impairment of recent memory and performance but frontal lobe functions were maintained. Laboratory data showed hyponatremia, elevation of antinuclear antibodies and IgG-antibodies to Epstein-Barr virus capsid antigen and Epstein-Barr virus nuclear antigen. A brain MRI revealed multiple lesions in the cerebral subcortex, cerebellum and brainstem. These lesions showed high signal intensity on T2-weighted images and enhanced high signal intensity on T1-weighted images using Gd-DTPA injection. A cystic mass was seen between bilateral lateral ventricles and contacted with the fornix and thalamus. Lymphomatoid granulomatosis was diagnosed by an open brain biopsy, which showed diffuse infiltration of small lymphocytes, histiocytes and plasma cells, especially around the small vessels. Epithelioid granuloma or necrosis was not seen. An immunohistochemical study showed that nearly all lymphocytes were MT-1 positive T lymphocytes. The patient was treated by whole brain irradiation (30Gy) and pulse therapy of methylprednisolone. Multiple lesions in the brain responded to these modalities with complete resolution of the lesions and clinical improvement. In this case, impressive multiple and cystic lesions seen on brain MRI disappeared by whole brain irradiation and steroid. Since etiologies of multiple lesions on MRI includes many possibilities, histological diagnostic methods should be performed to obtain a definitive diagnosis. This is the first case of lymphomatoid granulomatosis that showed multiple and cystic lesions on brain MRI in Japan.

Adult↗
PubMed1996

Neutral proteinases and their inhibitors in the loosening of total hip prostheses.

This study demonstrated the profile of the neutral proteinases, i) matrix metalloproteinases (MMP)-1, -2, -3, and -9, and ii) serine proteinases, elastase, cathepsin G, urokinase and tissue type plasminogen activators (uPA and tPA) as well as their inhibitors, namely, tissue inhibitor of matrix metalloproteinases (TIMP)-1, alpha 1-antitrypsin, alpha 1-antichymotrypsin, plasminogen activator inhibitor (PAI)-1 & 2, around loose hip prostheses to clarify the step in the cascade of biological host response in the loosening of replaced total hip joints. Immunohistochemical analysis showed the presence of MMPs (MMP-1, -2, -3, and -9) and serine proteinases (elastase, cathepsin G, uPA and tPA) both in the interface tissues and pseudocapsular tissues. Functional biochemical analysis revealed elevated proteolytic activities of MMPs, especially, MMP-2 and MMP-9, and also elastase and cathepsin G, which were not inhibited in loco, although the inhibitors, TIMP-1, alpha 1-antitrypsin and alpha 1-antichymotrypsin were detected. The results suggested the imbalance of neutral proteinase-inhibitor levels around loose hip prostheses. The proteolytic enzyme in the interface tissues could directly weaken periprosthetic tissues. The pseudocapsular tissues may induce cellular host response and proteolytic activation. Thus, the pseudocapsular tissues could contribute to the loosening via production of MMPs and serine proteinases into the synovial fluid. Pseudosynovial fluid, which showed high contents of inhibitors (TIMP-1, alpha 1-antitrypsin and alpha 1-antichymotrypsin) associated with low proteolytic potentials, could be produced to prevent the unfavorable elevation of proteolytic enzymes in loco as a local host response to implants.

Aged↗
PubMed1996

[Clinical evaluation of azithromycin in pediatric infections].

Azithromycin (AZM) was studied for its clinical efficacy in pediatric infections. The study on AZM was carried out in 43 patients whose diagnoses were given as follows: pharyngitis in five cases, tonsillitis in one, bronchitis in four, pneumonia in four, Mycoplasma pneumonia in 14, scarlet fever in nine, impetigo in four, pyodermia in one and Campylobacter enteritis in one. The patients received AZM once daily at 1.6 approximately 20.0 mg/kg body weight for three to five days. Effectiveness of AZM was evaluated in 39 cases and the drug was rated "excellent" in 15, "good" in 19, "fair" in one, "poor" in four, resulting in an efficacy rate of 87.2%. Twenty bacterial isolates were identified as causative isolates in 19 patients: Staphylococcus aureus, Streptococcus pyogenes, Streptococcus pneumoniae, Haemophilus influenzae, Campylobacter jejuni and Mycoplasma pneumoniae. AZM eradicated 16 isolates but four persisted after therapy. One patient complained of loose stool, while two patients were found with decreases in white blood cell counts, and seven showed increases in eosinophils. However, no serious case of adverse event was reported.

Administration, Oral↗
PubMed1996

[A case with an isolated cortical vein thrombosis].

A 45-year-old man was admitted to our hospital because of generalized seizure. He had epilepsy and mental retardation since age of two. On admission temperature was 37.9 degrees C but, nuchal rigidity and Kernig's sign were not present. There were no other abnormal findings on physical examination. Neurological examination revealed consciousness disturbance, generalized seizure and mental retardation. Right hemiparesis gradually developed after generalized seizure. Laboratory data did not show any abnormalites to induce cerebral venous thrombosis. A brain MRI revealed hyperintensity on T2-weighted images and slightly enhanced on T1-weighted images in the left frontal lobe, using Gd-DTPA. An increased signal was also noted in the superior sagittal sinus on T1-weighted images. The superior sagittal sinus was patent but the cortical vein in the left frontal lobe was not demonstrated on cerebral angiography. A diagnosis of an isolated cortical vein thrombosis was made by exploratory craniotomy. Anticoagulation with heparin was started. Although the cortical vein thrombosis usually co-exsists with dural sinus thrombosis, an isolated cortical vein thrombosis like this case was rather rare. A case with cerebral venous thrombosis localized only in the left frontal cortical vein is reported, but definitive etiology is not known.

Cerebral Cortex↗
PubMed1996

Genetic differentiation among three populations of Anopheles minimus of Guangxi and Yunnan Provinces in the People's Republic of China.

Electrophoretic studies were carried out on isozymes of 3 populations of Anopheles minimus collected from Guangxi and Yunnan Provinces of the People's Republic of China in 1993. Eight proteins were analyzed by 5% polyacrylamide gel electrophoresis. The most variable population, Y-F, was highly polymorphic at 14 of 20 loci (P=0.700) with an average heterozygosity H of 0.340. P values of 0.500 and 0.700, and H values of 0.220 and 0.210 were obtained for each from 'Guangxi-Lab' (GX-L) and 'Yunnan-Lab' (Y-L), respectively. Nei's genetic distances (D) between Y-L and GX-L, Y-F and GX-L, and Y-F and Y-L were 0.1131, 0.1946 and 0.1069, respectively. These results suggest that GX-L is distant from the 2 other populations, Y-L and Y-F, and that this genetic differentiation between the 2 populations of Yunnan and Guangxi Provinces corresponds to the forms A and B, which were morphologically classified by Xu et al (unpublished).

Alleles↗
PubMed1995

Cloning and characterization of the POX2 gene in Candida maltosa.

To study the function of acyl-CoA oxidase in an n-alkane-assimilating yeast, Candida maltosa, we isolated the POX2 gene which is a member of the acyl-CoA oxidase gene family. POX2 had a 2172-bp open reading frame (ORF) encoding an approx. 84-kDa polypeptide (724 amino acids (aa)) and was contiguous to POX4, another member of the acyl-CoA oxidase gene family on the same chromosomal DNA in a convergent arrangement. Northern blot analysis revealed that the expression of POX2 was induced in cells grown on oleic acid, n-tetradecanol and n-tetradecane. By using a gene-disruption technique, we constructed strains (termed P2DD and P4DD) in which both alleles of POX2 and POX4 were disrupted. The P2DD strain was normal in assimilation of various hydrophobic carbon sources, such as n-tetradecane, n-tetradecanol and oleic acid. In contrast, the P4DD strain was defective in its ability to grow on such hydrophobic carbon sources.

Acyl-CoA Oxidase↗
PubMed1995

Identification of a centromeric activity in the autonomously replicating TRA region allows improvement of the host-vector system for Candida maltosa.

A centromeric activity was identified in the previously isolated 3.8 kb DNA fragment that carries an autonomously replicating sequence (ARS) from the yeast Candida maltosa. Plasmids bearing duplicated copies of the centromeric DNA (dicentric plasmids) were physically unstable and structural rearrangements of the dicentric plasmids occurred frequently in the transformed cells. The centromeric DNA activity was dissociated from the ARS, which is 0.2 kb in size, and was delimited to a fragment at least 325 bp in length. The centromeric DNA region included the consensus sequences of CDEI (centromeric DNA element I) and an AT-rich CDEII-like region of Saccharomyces cerevisiae but had no homology to the functionally critical CDEIII consensus. A plasmid bearing the whole 3.8 kb fragment was present in 1-2 copies per cell and was maintained stably even under non-selective culture conditions, while a plasmid having only the 0.2 kb ARS was unstable and accumulated to high copy numbers. The high-copy-number plasmid allowed us to overexpress a gene to a high level, which had never been attained before, under the control of both constitutive and inducible promoters in C. maltosa.

Base Sequence↗
PubMed1995

Thermostable peroxidase activity with a recombinant antibody L chain-porphyrin Fe(III) complex.

In order to engineer a new type of catalytic antibody, we attempt to use a monoclonal antibody L chain as a host protein for a porphyrin. TCPP (meso-tetrakis(4-carboxyphenyl)porphyine) was chemically synthesized and Balb/c mice were immunized using TCPP as a hapten. Two hybridoma cells (03-1, 13-1), that produce monoclonal antibody against TCPP, were obtained. Genes for both H and L chains of monoclonal antibodies were cloned, sequenced and overexpressed using E. coli as a host. ELISA and fluorescence quenching method show that the independent antibody L chains from both Mab03-1 and Mab13-1 have specific interaction with TCPP. Furthermore, the recombinant antibody L chain from Mab13-1 exhibits much higher peroxidase activity than TCPP Fe(III) alone. The enzyme activity was detectable with pyrogallol and ABTS (2,2-azinobis-3-ethylbenzthiazolin-6-sulfonic acid) but not with catechol. This new catalytic antibody was extremely thermostable. Optimum temperature of the peroxidase reaction by the complex of 13-1L chain and TCPP Fe(III) was 90 degrees C, while that the TCPP Fe(III) alone was 60 degrees C.

Amino Acid Sequence↗
PubMed1995

Aspartyl-tRNA synthetase of the hyperthermophilic archaeon Pyrococcus sp. KOD1 has a chimerical structure of eukaryotic and bacterial enzymes.

The aspartyl-tRNA synthetase (AspRS)-encoding gene from the archaeon, Pyrococcus sp. KOD1 (KOD1), was cloned and sequenced, and expressed in Escherichia coli. The purified AspRS possessed an aminoacyation activity for tRNA extracted from KOD1. Analysis of the deduced amino-acid sequence (438 aa, 50,893 Da) revealed that the AspRS of KOD1 is a chimerical protein of bacteria and eukarya. Regional analysis showed high sequence similarity to higher eukaryotic enzymes in the central and C-terminal regions which are important for catalytic activity of the enzyme. In contrast, the N-terminal portion exhibits bacterial features and does not possess the higher eukaryotic sequence which is involved in high molecular weight (HMW) complex formation. These results suggest that archaeon AspRS has a eukaryotic-type catalytic mechanism without forming the HMW complex. This is the first example which shows that an archaeal protein possesses eukaryotic and bacterial features.

Amino Acid Sequence↗
PubMed1995

Analysis by in vitro mutagenesis of PP2A alpha okadaic acid responsive sequences.

It has been shown that the protein serine/threonine phosphatase type 2A alpha catalytic subunit (PP2A alpha) has a mutation consisting of a glycine substitution for cysteine at 269 in the okadaic acid resistant variant of CHO cells, and that the mutant protein is resistant to okadaic acid (Shima, H. et al. Proc. Natl. Acad. Sci. USA 91, 9267-9271, 1994). In this study we analyzed okadaic acid responsive sequences in PP2A alpha by introducing a mutation at around codon 269 of the cDNA strand. The recombinant mutant PP2A alpha proteins Y265F, C266G, Y267G and C269Y were resistant to okadaic acid, with IC50s of 10, 24, 20 and 10 nM, respectively, as opposed to the recombinant wild PP2A alpha protein which had an IC50 of 0.24 nM. This observation suggests that not only cysteine at 269, but also other YCY amino acids, between 265-267, are necessary for the high sensitivity of PP2A to okadaic acid.

Amino Acid Sequence↗
PubMed1995

Characterization of chitin synthase 2 of Saccharomyces cerevisiae. Implication of two highly conserved domains as possible catalytic sites.

Chitin synthase 2 of Saccharomyces cerevisiae was characterized by means of site-directed mutagenesis and subsequent expression of the mutant enzymes in yeast cells. Chitin synthase 2 shares a region whose sequence is highly conserved in all chitin synthases. Substitutions of conserved amino acids in this region with alanine (alanine scanning) identified two domains in which any conserved amino acid could not be replaced by alanine to retain enzyme activity. These two domains contained unique sequences, Glu561-Asp562-Arg563 and Gln601-Arg602-Arg603-Arg604-Trp605, that were conserved in all types of chitin synthases. Glu561 or arginine at 563, 602, and 603 could be substituted by glutamic acid and lysine, respectively, without significant loss of enzyme activity. However, even conservative substitutions of Asp562 with glutamic acid, Gln601 with asparagine, Arg604 with lysine, or Trp605 with tyrosine drastically decreased the activity, but did not affect apparent Km values for the substrate significantly. In addition to these amino acids, Asp441 was also found in all chitin synthase. The mutant harboring a glutamic acid substitution for Asp441 severely lost activity, but it showed a similar apparent Km value for the substrate. Amounts of the mutant enzymes in total membranes were more or less the same as found in the wild type. Furthermore, Asp441, Asp562, Gln601, Arg604, and Trp605 are completely conserved in other proteins possessing N-acetylglucosaminyltransferase activity such as NodC proteins of Rhizobium bacterias. These results suggest that Asp441, Asp562, Gln601, Arg604, and Trp605 are located in the active pocket and that they function as the catalytic residues of the enzyme.

Amino Acid Sequence↗