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Biomedical subjects

A Umeda

Publications and source records attributed to A Umeda.

At least 19 recordsLinked to original sources
PubMed1999

Morphological behavior of acidic and neutral liposomes induced by basic amphiphilic alpha-helical peptides with systematically varied hydrophobic-hydrophilic balance.

Lipid-peptide interaction has been investigated using cationic amphiphilic alpha-helical peptides and systematically varying their hydrophobic-hydrophilic balance (HHB). The influence of the peptides on neutral and acidic liposomes was examined by 1) Trp fluorescence quenched by brominated phospholipid, 2) membrane-clearing ability, 3) size determination of liposomes by dynamic light scattering, 4) morphological observation by electron microscopy, and 5) ability to form planar lipid bilayers from channels. The peptides examined consist of hydrophobic Leu and hydrophilic Lys residues with ratios 13:5, 11:7, 9:9, 7:11, and 5:13 (abbreviated as Hels 13-5, 11-7, 9-9, 7-11, and 5-13, respectively; Kiyota, T., S. Lee, and G. Sugihara. 1996. Biochemistry. 35:13196-13204). The most hydrophobic peptide (Hel 13-5) induced a twisted ribbon-like fibril structure for egg PC liposomes. In a 3/1 (egg PC/egg PG) lipid mixture, Hel 13-5 addition caused fusion of the liposomes. Hel 13-5 formed ion channels in neutral lipid bilayer (egg PE/egg PC = 7/3) at low peptide concentrations, but not in an acidic bilayer (egg PE/brain PS = 7/3). The peptides with hydrophobicity less than Hel 13-5 (Hels 11-7 and Hel 9-9) were able to partially immerse their hydrophobic part of the amphiphilic helix in lipid bilayers and fragment liposome to small bicelles or micelles, and then the bicelles aggregated to form a larger assembly. Peptides Hel 11-7 and Hel 9-9 each formed strong ion channels. Peptides (Hel 7-11 and Hel 5-13) with a more hydrophilic HHB interacted with an acidic lipid bilayer by charge interaction, in which the former immerses the hydrophobic part in lipid bilayer, and the latter did not immerse, and formed large assemblies by aggregation of original liposomes. The present study clearly showed that hydrophobic-hydrophilic balance of a peptide is a crucial factor in understanding lipid-peptide interactions.

Biophysical Phenomena↗
PubMed1999

Subtyping of Haemophilus influenzae strains by pulsed-field gel electrophoresis.

A total of 200 isolates of Haemophilus influenzae were analyzed by serotyping, biotyping, and pulsed-field gel electrophoresis (PFGE). A total of 178 epidemiologically unrelated strains of H. influenzae demonstrated a variety of genome patterns by PFGE, and 165 genotypes were thus obtained in this study. PFGE typing proved to have a much stronger discriminatory power than either serotyping or biotyping. Six serotype b strains were all classified into discrete genotypes. A PFGE analysis of 18 strains obtained from the nasopharynx, blood, and cerebrospinal fluid of patients with meningitis also supported the hypothesis that invasive H. influenzae disseminates from the nasopharynx to the bloodstream and then subsequently to other body sites. PFGE typing of 10 other strains isolated from household contacts of patients with H. influenzae infection revealed that the strain that caused the H. influenzae infection often colonized the nasopharynges of household contacts. Our findings suggest that PFGE analysis is useful for the epidemiological study of H. influenzae infection, even when the invasive disease is caused by serotype b strains.

Child↗
PubMed1998

BASH, a novel signaling molecule preferentially expressed in B cells of the bursa of Fabricius.

The bursa of Fabricius is a gut-associated lymphoid organ that is essential for the generation of a diversified B cell repertoire in the chicken. We describe here a novel gene preferentially expressed in bursal B cells. The gene encodes an 85-kDa protein, designated BASH (B cell adaptor containing SH2 domain), that contains N-terminal acidic domains with SH2 domain-binding phosphotyrosine-based motifs, a proline-rich domain, and a C-terminal SH2 domain. BASH shows a substantial sequence similarity to SLP-76, an adaptor protein functioning in TCR-signal transduction. BASH becomes tyrosine-phosphorylated with the B cell Ag receptor (BCR) cross-link or by coexpression with Syk and Lyn and associates with signaling molecules including Syk and a putative chicken Shc homologue. Overexpression of BASH results in suppression of the NF-AT activation induced by BCR-cross-linking. These findings suggest that BASH is involved in BCR-mediated signal transduction and could play a critical role in B cell development in the bursa.

Adaptor Proteins, Signal Transducing↗
PubMed1998

Spirochaete-like swimming mode of Campylobacter jejuni in a viscous environment.

The swimming patterns of Campylobacter jejuni in environments of low and high viscosity were examined by a video tracking method. In media of low viscosity, C. jejuni swam with an average velocity of 39.3 microm/s with frequent changes in direction. The velocity of C. jejuni increased in a medium at a little higher viscosity than that of a low viscosity buffer. In addition to this, C. jejuni showed a second increase of velocity in media of a high viscosity of about 40 centipoise. The swimming patterns at these two velocity peaks were compared. In the second peak the wild-type C. jejuni exhibited repeated back and forth swimming patterns which were more like the swimming pattern of spirochaetes than that of monotrichous bacteria. Thus C. jejuni may presumably use a different swimming mode in media of high viscosity than the original swimming mode mediated by the propelling force of the flagella. The spiral shape of this bacterium like that of spirochaetes may strongly influence its swimming ability in media of high viscosity such as the mucous layer of the intestinal tract.

Animals↗
PubMed1998

Surface characteristics of gram-negative and gram-positive bacteria in an atomic force microscope image.

Bacterial images can be obtained rather easily with an atomic-force microscope (AFM) in the magnification range of 5,000 to 30,000 times without any pretreatment of the specimens for such observations as chemical fixation, dehydration or staining. The bacterial shapes or the presence of flagella can be clearly recognized in these magnification ranges. In addition, we were also able to distinguish between gram-negative and gram-positive bacteria based on the specific wavy surface appearance of the former. AFM could thus be a useful tool for the identification of bacteria in the resolution range between electron and light microscopy.

Bacillus subtilis↗
PubMed1998

[Structure of the bacterial cell wall].

The fine structure of the cell walls of Gram-positive and -negative bacteria were determined by electron microscopy with the new technique of freeze substitution method, and analysed the cell wall structure of Staphylococcus aureus in detail. The surface of Staphylococcal cell wall was covered with a fuzzy coat consisting of fine fibers or electron-dence mass. This coat was completely removed after extraction of teichoic acid from the cell wall with trichloroacetic acid treatment, but was not affected by sodium dodecyl sulfate or trypsin treatment. It was suggested that many amount of teichoic acid was located on the surface of the cell wall and less inside the cell wall. The capsule of strain Smith diffuse was assumed to play the role as the barrier protected from the penetration of antibody against teichoic acid.

Cell Wall↗
PubMed1997

Displacement of gold marker in immunoelectron microscopy of human respiratory cilia.

Preembedding immunogold electron microscopy was performed to evaluate the position of outer arm dynein heavy chains in normal human respiratory cilia. Anti-dynein antibody (AD2), which is specific for sea urchin sperm flagellar dynein heavy chains, was used as primary antibody. Direct cross-sections of cilia were selected, and the distance between the center of a cilium and the center of a colloidal gold particle attached to the cilium (X) was measured. The distance between the center of a cilium and the farthest edge of an outer dynein arm of the cilium was measured by ordinary electron microscopy (Yo) and by immunoelectron microscopy (Yi). X was significantly longer than Yo and Yi. If it is assumed that the structure of respiratory cilia is dense and that antibodies are located at the outer side of the actual position of the heavy chains, then the average distance difference of approximately 90-120 A may represent the length of two conjugated antibodies. This length should be kept in mind when performing immunoelectron microscopy. The data suggest that AD2 recognizes the outer arm dynein heavy chains of normal human respiratory cilia.

Adult↗
PubMed1997

A structural analysis of the regularly arranged porin on the outer membrane of Campylobacter jejuni based on correlation averaging.

A negatively stained electron micrograph of regularly arranged porin proteins of Campylobacter jejuni on the isolated outer membrane of bacteria was analyzed in detail by the correlation averaging method using a computer-assisted program. The results showed that the porin of C. jejuni had a trimeric structure separated by about 10.4 +/- 0.15 nm. In addition, the pores in the trimers were also separated by about 4.3 +/- 0.1 nm.

Campylobacter jejuni↗
PubMed1997

Synthesis of oligodeoxyribonucleotide containing novel C-5 reactive 2'-deoxyuridine derivative and its functional modification via post-synthetic technique.

2'-Deoxyuridine derivatives bearing an activated ester at C-5 position were synthesized and was examined their use for the preparation of modified oligodeoxyribonucleotides (ODNs) by a post-modification method. The ODNs containing cyanomethyl ester at C-5 position of the deoxyuridine residue reacted easily with a primary amine of several functional molecules under the mild condition to give the corresponding modified ODNs.

Base Sequence↗
PubMed1996

Electron microscopy of the major outer membrane protein of Campylobacter jejuni.

The surfaces of the disrupted-cell surfaces of the Campylobacter jejuni strains FUM158432 and M1 were examined using the negative-staining technique and electron microscopy. The surfaces of the whole cells and the outer membranes were covered with small dark dots which, in some areas, were arranged in hexagonal patterns. The hexagonal arrangement was more clearly seen in extracted outer membrane. The size of each structure was measured based on a center-to-center distance with the adjacent structure, and was determined to be 9.9 +/- 0.9 nm. A profile of the proteins in the outer membrane by SDS-PAGE, performed in 0.1% SDS and at 100 C, showed 42 kDa proteins to comprise the major outer membrane protein of this bacterium. Digestion of the outer membrane materials with proteinase reduced this protein band in the SDS-PAGE, and the amount of dark dots on the electron micrograph indicated the structure to be the major outer membrane protein (porin) of this bacterium. The power spectrogram of a computer-assisted Fourier transformation of the hexagonally arranged porin proteins suggests that the porin has a trimeric structure rather than a monomeric one.

Bacterial Proteins↗
PubMed1996

Epidemiologic application of pulsed-field gel electrophoresis to an outbreak of Campylobacter fetus meningitis in a neonatal intensive care unit.

An outbreak of nosocomial Campylobacter fetus meningitis occurred in a neonatal intensive care unit (NICU). Eight C. fetus strains were isolated from 4 infants with meningitis, the mother of the index patient and 2 infants who were asymptomatic intestinal carriers. The pulsed-field gel electrophoresis (PFGE) pattern with the restriction endonucleases Smal and Sall were found to be identical for the nosocomial C. fetus isolates, but the patterns were different from those of sporadic strains. These nosocomial strains were strongly suspected to be a single strain. The finding revealed that the index patient was infected by the mother, and that the outbreak developed from this patient by cross-infection. This is the first confirmed nosocomial C. fetus meningitis outbreak spread by cross-infection in a NICU.

Adult↗
PubMed1995

Reduction of tissue edema by microdialysis.

OBJECTIVE: This is the first report (to our knowledge) of the use of tissue microdialysis to reduce tissue edema. In this study, a hyperosmotic solution was perfused through microdialysis catheters, allowing direct treatment of interstitial edema by osmosis. DESIGN: First, the catheter and perfusate characteristics were tested in vitro. A physiologic, controlled trial was then performed, with two outcome variables: osmolarity of the effluent and tissue water content. SUBJECTS: Twenty male Sprague-Dawley rats. One rat was withdrawn. INTERVENTIONS: Tissue microdialysis catheters were implanted in the rats. The control side of the animals was not perfused. The experimental side was perfused for 9 hours. RESULTS: Osmolarity of the perfusate was reduced 16.5 mOsm after passing through the catheter, indicating that fluid was removed from the tissue. Tissue edema was reduced by an average 1.8 mL of fluid per 100 g of wet tissue. CONCLUSIONS: Tissue microdialysis removed tissue fluid and reduced edema. This treatment may have a beneficial effect on edematous tissues. Potential use and limitations of this therapeutic modality are discussed.

Animals↗
PubMed1995

Immunohistochemical analysis of rat and human respiratory cilia with anti-dynein antibody: comparison between normal cilia and pathological cilia in primary ciliary dyskinesia.

Wistar Imamichi rat and human respiratory cilia were examined with anti-dynein antibody (AD2), which is specific for sea urchin sperm flagellar dynein. AD2-labelled fresh-frozen normal rat and human cilia stained clearly by immunofluorescence and the peroxidase-antiperoxidase (PAP) technique. On immunoelectron microscopy, AD2 labelled the outer dynein arms of normal human cilia. Paraffin-embedded normal human cilia also stained by immunofluorescence, although not always clearly. Neither the cilia of WIC-Hyd male rats, an animal model of Kartagener's syndrome, nor human cilia from patients with primary ciliary dyskinesia (PCD) reacted positively by the immunofluorescence or PAP technique. Western blots of normal rat cilia yielded a single band of about 450 kDa. In conclusion, AD2 recognizes the outer arm dynein heavy chains of healthy cilia and may be useful in diagnosing and classifying PCD light microscopically especially when only paraffin-embedded specimens are available. This approach may be of potential use for better defining and classifying PCD.

Adolescent↗
PubMed1995

Typing of Staphylococcus aureus colonising human nasal carriers by pulsed-field gel electrophoresis.

Colonisation by Staphylococcus aureus in the nares of 120 outpatients and 63 healthy adults was studied for c. 2 years. Two states of carriage of S. aureus were confirmed: persistent carriage and persistent non-carriage. The states of carriage and non-carriage were quite stable and > 60% of the population of any of the study groups were stable non-carriers. The results of typing the strains isolated from the same individuals at different times with DNA fingerprinting by digestion with SmaI enzyme showed that all the stable carriers were persistently infected with the same strain and that changes in the strain seldom occurred.

Adult↗
PubMed1995

Typing of Staphylococcus epidermidis colonizing in human nares by pulsed-field gel electrophoresis.

From the nares of 11 healthy adults, 253 strains of coagulase negative staphylococcus were isolated and 88% of them were identified as Staphylococcus epidermidis using the API STAPH system. Chromosomal DNA fingerprinting of the isolated strains revealed that each person carried multiple types of S. epidermidis in his or her nares. The colonization of the strains was not stable; the types of the isolates changed in the first and the second examinations 5 months apart. The results contrasted with previous findings in which only one strain of S. aureus colonized persistently in the nares of healthy adults.

Adult↗