Biomedical subjects

A Ichige

Publications and source records attributed to A Ichige.

10 recordsLinked to original sources

PubMed2000

Cellular responses to postsegregational killing by restriction-modification genes.

Plasmids that carry one of several type II restriction modification gene complexes are known to show increased stability. The underlying mechanism was proposed to be the lethal attack by restriction enzyme at chromosomal recognition sites in cells that had lost the restriction modification gene complex. In order to examine bacterial responses to this postsegregational cell killing, we analyzed the cellular processes following loss of the EcoRI restriction modification gene complex carried by a temperature-sensitive plasmid in an Escherichia coli strain that is wild type with respect to DNA repair. A shift to the nonpermissive temperature blocked plasmid replication, reduced the increase in viable cell counts and resulted in loss of cell viability. Many cells formed long filaments, some of which were multinucleated and others anucleated. In a mutant defective in RecBCD exonuclease/recombinase, these cell death symptoms were more severe and cleaved chromosomes accumulated. Growth inhibition was also more severe in recA, ruvAB, ruvC, recG, and recN mutants. The cells induced the SOS response in a RecBC-dependent manner. These observations strongly suggest that bacterial cells die as a result of chromosome cleavage after loss of a restriction modification gene complex and that the bacterial RecBCD/RecA machinery helps the cells to survive, at least to some extent, by repairing the cleaved chromosomes. These and previous results have led us to hypothesize that the RecBCD/Chi/RecA system serves to destroy restricted "nonself" DNA and repair restricted "self" DNA.

Chromosomes, Bacterial↗

PubMed1997

Genetic analysis of the Rhizobium meliloti bacA gene: functional interchangeability with the Escherichia coli sbmA gene and phenotypes of mutants.

The Rhizobium meliloti bacA gene encodes a function that is essential for bacterial differentiation into bacteroids within plant cells in the symbiosis between R. meliloti and alfalfa. An Escherichia coli homolog of BacA, SbmA, is implicated in the uptake of microcin B17, microcin J25 (formerly microcin 25), and bleomycin. When expressed in E. coli with the lacZ promoter, the R. meliloti bacA gene was found to suppress all the known defects of E. coli sbmA mutants, namely, increased resistance to microcin B17, microcin J25, and bleomycin, demonstrating the functional similarity between the two proteins. The R. meliloti bacA386::Tn(pho)A mutant, as well as a newly constructed bacA deletion mutant, was found to show increased resistance to bleomycin. However, it also showed increased resistance to certain aminoglycosides and increased sensitivity to ethanol and detergents, suggesting that the loss of bacA function causes some defect in membrane integrity. The E. coli sbmA gene suppressed all these bacA mutant phenotypes as well as the Fix- phenotype when placed under control of the bacA promoter. Taken together, these results strongly suggest that the BacA and SbmA proteins are functionally similar and thus provide support for our previous hypothesis that BacA may be required for uptake of some compound that plays an important role in bacteroid development. However, the additional phenotypes of bacA mutants identified in this study suggest the alternative possibility that BacA may be needed for membrane integrity, which is likely to be critically important during the early stages of bacterial differentiation within plant cells.

Anti-Bacterial Agents↗

PubMed1996

Genetic analysis of Rhizobium meliloti bacA-phoA fusion results in identification of degP: two loci required for symbiosis are closely linked to degP.

The function of the Rhizobium meliloti bacA gene, which is a homolog of the Escherichia coli sbmA gene, is required for an intermediate step in nodule development. A strain carrying the bacA386::TnphoA fusion was mutagenized with N-methyl-N'-nitro-N-nitrosoguanidine, and three mutants that had higher levels of alkaline phosphatase activity were identified. The mutations in these strains were recessive and mapped to the same genetic locus. The gene affected by these mutations was identified and sequenced and was found to be a homolog of the E. coli degP gene, which encodes a periplasmic endopeptidase. Although degP function is important for the virulence of certain intracellular pathogens of mammals, it is not required for the R. meliloti-alfalfa symbiosis. The genetic analyses involving degP were complicated by the presence of a locus immediately upstream of depP that was lethal when present in multiple copies in a DegP- background. R. meliloti derivatives carrying insertion mutations in this locus displayed an N,N,N',N'-tetramethyl-p-phenylenediamine oxidase-negative phenotype, elicited the formation of white cylindrical nodules that did not fix nitrogen, and grew slowly in rich medium, suggesting that the locus was a cyc gene encoding a protein involved in the biosynthesis of a component or components of a respiratory chain. The previously identified fix-382::TnphoA, which similarly causes the formation of white cylindrical nodules that do not fix nitrogen, was shown to affect a gene that is separate from this cyc gene but extremely closely linked to it.

Alkaline Phosphatase↗

PubMed1994

Storage and utilization of images in otorhinolaryngology.

The amount of data in the field of otorhinolaryngology has rapidly increased, in proportion to the growing number of patients. Medical imaging has especially expanded and the percentage of image data in all information is also large. Because the space to preserve image films is increasing, it is very important to preserve them and make them easily available. Therefore, we have established a graphic filling system for storing endoscopic and radiographic images on VHS video tape and magnet-optical disk (MOD), using a personal computer. The MOD filing system is useful for storing a large amount of medical records. The user can simultaneously see the text data and the picture image on a display, and thus this system can be utilized as a database for both decision making and medical research.

Barium Sulfate↗

PubMed1993

A Rhizobium meliloti homolog of the Escherichia coli peptide-antibiotic transport protein SbmA is essential for bacteroid development.

Alfalfa nodules induced by a Rhizobium meliloti strain carrying the bacA386::TnphoA mutation (formerly fix386::TnphoA) were examined by light and electron microscopy. These ineffective nodules were found to contain bacteria within infection threads, but no mature bacteroids were observed. A closer examination revealed that there were undeveloped senescent bacteroids in the plant cells of the nodule invasion zone, strongly suggesting that the symbiotic defect of the bacA386::TnphoA mutant is attributable to an early block in bacteroid development. The expression of the bacA gene in effective nodules was monitored with a bacA-phoA fusion and found to be strongest in the region where developing bacteroids are found. The bacA+ gene was cloned and sequenced. Sequence analysis indicated that BacA is probably an integral inner membrane protein with seven transmembrane domains and that it is extremely homologous to Escherichia coli SbmA, an inner membrane protein required for the uptake of microcin B17, a peptide antibiotic. Southern blotting experiments indicate that a gene closely related to bacA/sbmA is found in many bacteria, including some that invade eukaryotic cells. Possible roles for BacA in symbiosis are discussed.

Amino Acid Sequence↗

PubMed1990

Proximal clipping of dissecting intracranial vertebral aneurysm--effect of balloon Matas test with neurophysiological monitoring. Case report.

A case of repeated subarachnoid haemorrhage (SAH) caused by rupture of a dissecting intracranial vertebral aneurysm is reported. The clinical manifestations, angiographic findings, pre-operative assessment with neurophysiological monitoring, and surgery are presented. A review of the literature suggests that this type of intracranial aneurysm is being recognized with increasing frequency in SAH and fatality, and therefore exploration and treatment of vertebrobasilar (V-B) dissecting aneurysms is necessary. We emphasize that a balloon Matas test with monitoring of somatosensory evoked potentials (SEP), auditory brain stem responses (ABR), and its wedge pressure in occluding the vertebral artery before operation are objective assessments of treatment for dissecting intracranial vertebral aneurysm.

Aortic Dissection↗

PubMed1989

Establishment of gene transfer systems for and construction of the genetic map of a marine Vibrio strain.

Two gene transfer systems were established for a marine bacterium, Vibrio sp. strain 60. One was generalized transduction with a newly isolated bacteriophage, As3, and the other was conjugal gene transfer by the use of newly constructed transposon-facilitated recombination (Tfr) donors. As3 transduced various chromosomal markers at frequencies of 10(-4) to 10(-6). Tfr donors, which were constructed by introducing transposon Tn10 into both plasmid RP4 and the chromosome, mediated the polarized transfer of chromosomal genes from the sites of Tn10 insertion on the chromosome. By means of these gene transfer systems, a genetic map of the vibrio chromosome was constructed.

Bacteriophages↗

PubMed1988

Isolation and characterization of mutants of a marine Vibrio strain that are defective in production of extracellular proteins.

A marine Vibrio strain, Vibrio sp. strain 60, produces several extracellular proteins, including protease, amylase, DNase, and hemagglutinin. Mutants of Vibrio sp. strain 60 (epr mutants) pleiotropically defective in production of these extracellular proteins were isolated. They fell into two classes, A and B. In class A, no protease activity was detected in the cells either, whereas in class B, considerable protease activity was detected in the cells. Gel electrophoretic analysis revealed that the protease detected in class B mutant cells was similar to the protease excreted by the parent strain. In addition, the protease in class B mutant cells was found to be localized in the periplasmic space. These results suggest that the passage of the protease through the outer membrane is blocked in class B mutants. Comparison of membrane protein profiles by polyacrylamide gel electrophoresis revealed that all the epr mutants contained an increased amount of a 94,000-Mr protein that may be an outer membrane protein. Four epr mutations were mapped in two different regions of the Vibrio chromosome by transduction; two class A mutations and one class B mutation were located close to each other, whereas another class B mutation was located in a different region of the chromosome.

Amylases↗

PubMed1988

Nationwide investigation on diagnostic methods for facial palsy.

We investigated the present status concerning the performance of examinations of facial nerve function for facial palsy, based on statistics obtained from the project supported by a Grant-in-Aid for Co-operative Research (A) from the Ministry of Education. The project is called An Epidemiological and Clinical Study on the Idiopathic Facial Palsy. In an analysis of the questionnaire "individual investigation card for idiopathic facial palsy" obtained from 28 medical facilities throughout Japan between 1984 and 1986, the outline of the examinations performed for peripheral facial palsy was examined.

Electrodiagnosis↗

PubMed1988

Results of facial nerve decompression.

To evaluate the benefit of facial nerve decompression for Bell's palsy and Hunt's syndrome, prognoses of patients who underwent surgery were compared with those of patients treated conservatively. Facial nerve decompression was slightly effective only in the Bell's palsy patients having 95-100% maximal nerve degeneration, when it was performed at a very early stage of the palsy. No significant difference in the incidence of sequelae was observed between surgically and conservatively treated groups. In Hunt's syndrome, the prognosis for the surgical group was poorer than that of the conservatively treated group.

Electrodiagnosis↗