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Biomedical subjects

I Uchida

Publications and source records attributed to I Uchida.

At least 73 records · Page 4Linked to original sources
PubMed1993

A conjugative plasmid pTE195 coding for drug resistance and virulence phenotypes from Salmonella naestved strain of calf origin.

Salmonella naestved strain AHI-195, of calf origin, harbors a conjugative 95 megadalton (MDa) plasmid, pTE195, which encodes resistance to tetracycline and chloramphenicol and belongs to incompatibility group FII. Moreover, DNA homology between pTE195 and the Salmonella dublin virulence plasmid pTE800 was revealed by digestion with several restriction endonucleases and confirmed by hybridization with different specific probes. These results indicate that pTE195 carries not only genes for drug resistance but also genes for virulence phenotypes such as serum resistance and mouse lethality.

Animals↗
PubMed1993

Identification of a novel gene, dep, associated with depolymerization of the capsular polymer in Bacillus anthracis.

Bacillus anthracis produces a gamma-linked poly-D-glutamic acid capsule that is essential for virulence. A 6.2 kb fragment of B. anthracis DNA (cap), when present in Escherichia coli, produces a capsular polymer that is immunologically identical to that produced by B. anthracis. By immunodiffusion analysis of E. coli strains carrying varying portions of the cap region, we identified a novel gene (dep) responsible for degradation of the capsular polymer of B. anthracis. The simultaneous presence of the cap region and the dep gene caused production of low-molecular-weight, degraded capsular polymer both in E. coli and in B. anthracis, whereas the cap region alone caused production of a high-molecular-weight capsule. The dep gene mapped immediately downstream of the cap region within a 1.8 kb fragment and was transcribed in the same direction. This fragment was sequenced and a 1401 bp open reading frame (ORF) was found that is predicted to encode a peptide with molecular weight of 51,460. By in vitro transcription-translation analysis, this ORF was shown to be the dep gene product. The deduced amino acid sequence of the dep product has sequence similarity to E. coli and mammalian gamma-glutamyltranspeptidase (GGT). However, the Dep protein did not have GGT activity. The Dep protein appears to be an enzyme that catalyses the hydrolysis of the poly-D-glutamic acid capsule. Although the biological functions of the dep gene are unknown, it is possible that low-molecular-weight, diffusible polyglutamates produced through the action of the dep gene may act to inhibit host defence mechanisms.

Amino Acid Sequence↗
PubMed1993

Cloning and characterization of a gene whose product is a trans-activator of anthrax toxin synthesis.

The 184-kb Bacillus anthracis plasmid pXO1, which is required for virulence, contains three genes encoding the protein components of anthrax toxin, cya (edema factor gene), lef (lethal factor gene), and pag (protective antigen gene). Expression of the three proteins is induced by bicarbonate or serum. Using a pag-lacZ transcriptional construct to measure pag promoter activity, we cloned in Bacillus subtilis a gene (atxA) whose product acts in trans to stimulate anthrax toxin expression. Deletion analysis located atxA on a 2.0-kb fragment between cya and pag. DNA sequencing identified one open reading frame encoding 476 amino acids with a predicted M(r) of 55,673, in good agreement with the value of 53 kDa obtained by in vitro transcription-translation analysis. The cloned atxA gene complemented previously characterized Tn917 insertion mutants UM23 tp29 and UM23 tp32 (J. M. Hornung and C. B. Thorne, Abstr. 91st Gen. Meet. Am. Soc. Microbiol. 1991, abstr. D-121, p. 98), which are deficient in synthesis of all three toxin proteins. These results demonstrate that the atxA product activates not only transcription of pag but also that of cya and lef. beta-Galactosidase synthesis from the pag-lacZ transcriptional fusion construct introduced into an insertion mutant (UM23 tp62) which does not require bicarbonate for toxin synthesis indicated that additional regulatory genes other than atxA play a role in the induction of anthrax toxin gene expression by bicarbonate.

Amino Acid Sequence↗
PubMed1993

A cryptic DNA sequence, isolated from Actinobacillus pleuropneumoniae, confers a hemolytic activity upon Escherichia coli K12 strains.

A hemolytic recombinant clone on Escherichia coli was obtained from a genomic library of Actinobacillus pleuropneumoniae. The clone possessed a recombinant plasmid, pHLY1, carrying an insert DNA of 1 kilobases. A 21 kilodaltons protein, which is assumed to be a fusion protein with a tetracycline resistant protein of pBR322, was encoded by pHLY1. The nucleotide sequence and its deduced amino acid sequence were different from those of the previously reported hemolysin genes of A. pleuropneumoniae. Furthermore, the amino acid sequence did not show a significant homology with other published sequences in the SWISS-PROT Protein Sequence Data Bank.

Actinobacillus pleuropneumoniae↗
PubMed1993

Effects of the novel thyrotropin-releasing hormone analogue Na -((1S,2R)-2-methyl-4-oxocyclopentylcarbonyl)-L-histidyl-L-prol ina mide monohydrate on the central nervous system in mice and rats.

The central nervous system (CNS) effects of a novel thyrotropin-releasing hormone (TRH) analogue, JTP-2942 (Na-alpha- ((1S,2R)-2-methyl-4-oxocyclopentylcarbonyl)-L-histidyl-L-pro linamide monohydrate, CAS 131404-34-7) were investigated and compared with those of TRH. When administrated subcutaneously, JTP-2942 was about 80 times more potent than TRH in the antagonization of reserpine-induced hypothermia, and when administrated intravenously it was about 16 times more potent than TRH in the potentiation of flexor reflexes. Furthermore, oral administration of JTP-2942 was able to antagonize a chlorpromazine-induced reduction in locomotor activity, while TRH was far less effective. In tests on the recovery from pentobarbital-induced sleep and disturbance of consciousness induced by concussive head trauma, JTP-2942 was about 30 and 3 times more potent than TRH, respectively. Thus, JTP-2942 had a far stronger and more persistent action compared with TRH in regard to these effects. However, JTP-2942 had a 3-fold lower effect on thyroid stimulating hormone (TSH) release than TRH. These results suggest that the stimulatory effects of JTP-2942 are selective for the CNS and that this TRH analogue may be applicable to clinical use.

Animals↗
PubMed1993

Loss of telomeric DNA during aging of normal and trisomy 21 human lymphocytes.

The telomere hypothesis of cellular aging proposes that loss of telomeric DNA (TTAGGG) from human chromosomes may ultimately cause cell-cycle exit during replicative senescence. Since lymphocytes have a limited replicative capacity and since blood cells were previously shown to lose telomeric DNA during aging in vivo, we wished to determine: (a) whether accelerated telomere loss is associated with the premature immunosenescence of lymphocytes in individuals with Down syndrome (DS) and (b) whether telomeric DNA is also lost during aging of lymphocytes in vitro. To investigate the effects of aging and trisomy 21 on telomere loss in vivo, genomic DNA was isolated from peripheral blood lymphocytes of 140 individuals (age 0-107 years), including 21 DS patients (age 0-45 years). Digestion with restriction enzymes HinfI and RsaI generated terminal restriction fragments (TRFs), which were detected by Southern analysis using a telomere-specific probe (32P-(C3TA2)3). The rate of telomere loss was calculated from the decrease in mean TRF length, as a function of donor age. DS patients showed a significantly higher rate of telomere loss with donor age (133 +/- 15 bp/year) compared with age-matched controls (41 +/- 7.7 bp/year) (P < .0005), suggesting that accelerated telomere loss is a biomarker of premature immunosenescence of DS patients and that it may play a role in this process. Telomere loss during aging in vitro was calculated for lymphocytes from four normal individuals, grown in culture for 10-30 population doublings. The rate of telomere loss was approximately 120 bp/cell doubling, comparable to that seen in other somatic cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1992

Molecular studies of parental origin and mosaicism in 45,X conceptuses.

The present report summarizes molecular studies of parental origin and sex chromosome mosaicism in forty-one 45,X conceptuses, consisting of 29 spontaneous abortions and 12 liveborn individuals with Turner syndrome. Our studies indicate that most 45,X conceptuses have a single, maternally derived X chromosome, regardless of whether the conceptus is liveborn or spontaneously aborted. In studies of mosaicism, our identification of X- and Y-chromosome mosaics among 45,X spontaneous abortions indicates that mosaicism does not ensure survival to term of 45,X fetuses. However, the incidence of sex chromosome mosaicism is substantially higher in liveborn than in aborted 45,X conceptuses, indicating that the presence of a second cell line increases the likelihood of survival to term.

Abortion, Spontaneous↗
PubMed1992

Prolongation of canine epidural anesthesia by liposome encapsulation of lidocaine.

The purpose of our study was to produce a long-acting lidocaine by using a liposome that would entrap the drug. Egg yolk phosphatidylcholine and cholesterol were used as liposome materials. After epidural administration, the pharmacodynamics and pharmacokinetics of liposomal and free lidocaine were studied in 20 dogs. Two percent liposomal or free lidocaine (3.0 mL) was injected into the lumbar epidural space. Nerve blocking effects were estimated by measuring somatosensory evoked potentials. Recovery time from the epidural block in the liposomal lidocaine group (170 +/- 49.5 min) was approximately three times longer than that in the free lidocaine group (61 +/- 18.1 min). The areas under the drug concentration-time curves (AUC0-infinity) and time to maximal concentration (Tmax) in the liposomal lidocaine group were significantly larger than those in the free lidocaine group. These results suggest that the prolongation of epidural blockade by liposomal lidocaine is caused by a slow release of the drug from liposomes. The present study suggests that liposomal lidocaine can be used as a long-acting local anesthetic.

Amines↗
PubMed1992

[Calculation algorithm of three-dimensional absorbed dose distribution due to in vivo administration of nuclides for radiotherapy].

In the in vivo administration of radionuclides for radiotherapy including radioimmunotherapy, an algorithm is proposed for the purpose of calculating three-dimensional absorbed dose distributions of tumors and adjacent tissues, and neighboring organs. The absorbed dose distribution due to the algorithm is given by convolution of the three-dimensional dose matrix for a unit cubic voxel containing unit cumulated activity, with the three-dimensional matrix of the cumulated activity distribution given by the same voxel size above. The dose calculation algorithm does not depend upon the source size, the source shape, and the nonuniform and irregular activity distribution. In addition, it can exceedingly decrease computation time compared to other calculation algorithms. Computer simulations were performed using the MIRD thyroid phantom for 32P, 90Y, 131I, 186Re, and 188Re that appear promising for radioimmunotherapy, and their results verified the validity of the proposed calculation algorithm and high accuracy of the calculations.

Algorithms↗
PubMed1991

Effects of volatile anesthetics on bacteriorhodopsin in purple membrane, Halobacterium halobium cells and reconstituted vesicles.

In this study, we have investigated effects of volatile anesthetics on absorption spectra, proton pumping activity and decay of photointermediate M of bacteriorhodopsin (bR) in differently aggregated states. Anesthetics used in this study are ether-type general anesthetics; enflurane and sevoflurane. The observed effects on bR depend not only on variety or concentration of anesthetics but also strongly on the aggregation state of bR molecules in the membrane. In purple membrane (PM), bR having maximum light absorption at 567 nm (bR567) is formed in the presence of sevoflurane or a small amount of enflurane, while a species absorbing maximally at 480 nm (bR480) is formed upon the addition of large amounts of enflurane. X-ray diffraction studies show that the former species maintains crystallinity of PM, but the latter does not. In reconstituted vesicles where bR molecules exist as monomer, even sevoflurane forms bR480. Flash photolysis experiments show that bR567 contains a shorter-lived M intermediate absorbing maximally at 412 nm in the photoreaction cycle than bR does and that bR480 contains at least two long-lived M intermediates which seem to absorb maximally near and at lower than 380 nm. The measurements of light-induced pH changes of the whole cells and of the reconstituted vesicles in the presence of the anesthetics indicate that bR567 has a enhanced proton pumping efficiency, while bR480 has a quite low or no activity. No significant difference was observed in the anesthetic action between two inversely pumping vesicles. These observations suggest that on the formation of bR480, anesthetics enter into the membrane and affect the protein-lipid interaction.

Anesthetics↗
PubMed1991

Immobilized-enzyme electrode for nicotinamide adenine dinucleotide (reduced form) (NADH) sensing and application to the kinetic studies of NADH dependent dehydrogenases.

Amperometric determination of nicotinamide adenine dinucleotide (reduced form) (NADH) at an immobilized-diaphorase (Dp) electrode is described. The measurement was conducted using ferrocenylmethanol as a mediator in a stirred solution at 0.20 V versus a saturated calomel electrode. A linear relationship between the steady-state current and the concentration of NADH was found over the range 0.005-0.125 mmol dm-3. The immobilized-Dp electrode showed outstanding stability and the current response reached a steady state within 2-3 seconds upon addition of NADH. The proposed electrode was used to follow the reactions of pig heart lactate dehydrogenase and horse liver alcohol dehydrogenase. The kinetic investigation using the immobilized-Dp electrode gave the kinetic parameters (Michaelis constants, Km values, and maximum velocities, Vm values), which were in satisfactory agreement with those determined by a conventional spectrophotometric method.

Electrodes↗