PubMed Health⌕ Search

Biomedical subjects

C Storey

Publications and source records attributed to C Storey.

15 recordsLinked to original sources
PubMed2004

The eyes have it.

Explore the source record for details and available documents.

Diagnostic Techniques, Ophthalmological↗
PubMed2001

Affinities of beta-lactams for penicillin binding proteins of Chlamydia trachomatis and their antichlamydial activities.

Binding affinities of beta-lactam antibiotics for the three penicillin binding proteins (PBPs) from Chlamydia trachomatis were determined in vitro and compared with their antichlamydial activities. Mecillinam selectively inhibited PBP1, with a 50% inhibitory concentration for PBP1 binding (0.2 microg/ml) similar to the MIC (0.1 microg/ml) and minimum bactericidal concentration (0.25 microg/ml). Although the other beta-lactams inhibited a wider range of PBPs than mecillinam, their antichlamydial activities were inferior to that of mecillinam.

Amdinocillin↗
PubMed2000

Self absorption of alpha and beta particles in a fiberglass filter.

Environmental air sampling uses fiberglass filters to collect particulate matter from the air and then a gas flow detector to measure the alpha and beta activity on the filter. When counted, the filter is located close to the detector so the alpha and beta particles emerging from the filter travel toward the detector at angles ranging from zero to nearly 90 degrees to the normal to the filter surface. The particles at small angles can readily pass through the filter, but particles at large angles pass through a significant amount of filter material and can be totally absorbed. As a result, counting losses can be great. For 4 MeV alpha particles, the filter used in this experiment absorbs 43% of the alpha particles; for 7.5 MeV alphas, the absorption is 13%. The measured beta activities also can have significant counting losses. Beta particles with maximum energies of 0.2 and 2.0 MeV have absorptions of 44 and 2%, respectively.

Absorption↗
PubMed2000

RNA polymerase inhibitors with activity against rifampin-resistant mutants of Staphylococcus aureus.

A collection of rifampin-resistant mutants of Staphylococcus aureus with characterized RNA polymerase beta-subunit (rpoB) gene mutations was cross-screened against a number of other RNA polymerase inhibitors to correlate susceptibility with specific rpoB genotypes. The rpoB mutants were cross-resistant to streptolydigin and sorangicin A. In contrast, thiolutin, holomycin, corallopyronin A, and ripostatin A retained activity against the rpoB mutants. The second group of inhibitors may be of interest as drug development candidates.

Anti-Bacterial Agents↗
PubMed1999

In situ fiber-optic oxygen consumption measurements from a working mouse heart.

Luminescence-based imaging-fiber oxygen sensors (IFOSs) were utilized for the in situ measurement of oxygen consumption from intact perfused mouse hearts. IFOSs were fabricated using a technically expedient, photoinitiated polymerization reaction whereby an oxygen-sensitive polymer matrix was immobilized in a precise location on an imaging fiber's distal face. The oxygen-sensing layer used in this work comprised a transition metal complex, Ru(Ph2phen)3(2+), entrapped in a gaspermeable photopolymerizable siloxane membrane (PS802). The transduction mechanism was based upon the oxygen collisional quenching of the ruthenium complex luminescence; detection was performed utilizing an epi-fluorescence microscope/charge coupled device imaging system. IFOS measurements from working mouse hearts were validated through concurrent, blind, ex situ blood gas analyzer (BGA) measurements. The BGA and IFOS methodologies were utilized successfully to measure oxygen concentrations in aortic and pulmonary artery perfusates from the working mouse heart before and after isoproterenol administration. Coupled with coronary-flow measurements, these data were used to calculate myocardial oxygen consumption. Regression analysis of measurements of myocardial oxygen consumption showed that there was a strong correlation between the values generated by the BGA sampling and those obtained via in situ IFOS methods. To our knowledge, this research represents the first report of in situ fiber-optic sensor monitoring of oxygen content from the intact, beating mouse heart.

Animals↗
PubMed1999

Sustained ex vivo expansion of hematopoietic stem cells mediated by thrombopoietin.

The hematopoietic stem cell (HSC) is defined as a cell that can either self-replicate or generate daughter cells that are destined to commit to mature cells of different specific lineages. Self-replication of the most primitive HSC produces daughter cells that possess a long (possibly unlimited) clonal lifespan, whereas differentiation of HSC produces daughter cells that demonstrate a progressive reduction of their clonal lifespan, a loss of multilineage potential, and lineage commitment. Previous studies indicated that the proliferation of HSC ex vivo favors differentiation at the expense of self-replication, eventually resulting in a complete loss of HSC. In contrast, transplantation studies have shown that a single HSC can repopulate the marrow of a lethally irradiated mouse, demonstrating that self-renewal of HSC occurs in vivo. Thrombopoietin (TPO) has been shown to function both as a proliferative and differentiative factor for megakaryocytes and as a survival and weakly proliferative factor for HSC. Our studies focused on the effects of exogenous TPO on HSC in mouse long-term bone marrow cultures (LTBMC). Previous results indicate that HSC decline in LTBMC in the absence of TPO. In contrast, the continuous presence of TPO resulted in the generation of both long- and short-term repopulating HSC as detected by an in vivo competitive repopulation assay. HSC were generated over a 4-month period at concentrations similar to normal bone marrow. Our results demonstrate that TPO can mediate the self-replication of HSC in LTBMC, and provide proof that HSC can self-replicate ex vivo.

Animals↗
PubMed1997

Evolutionary relationships among members of the genus Chlamydia based on 16S ribosomal DNA analysis.

Nucleotide sequences from strains of the four species currently in the genus Chlamydia, C. pecorum, C. pneumoniae, C. psittaci, and C. trachomatis were investigated. In vitro-amplified RNA genes of the ribosomal small subunit from 30 strains of C. pneumoniae and C. pecorum were subjected to solid-phase DNA sequencing of both strands. The human isolates of C. pneumoniae differed in only one position in the 16S rRNA gene, indicating genetic homogeneity among these strains. Interestingly, horse isolate N16 of C. pneumoniae was found to be closely related to the human isolates of this species, with a 98.9% nucleotide similarity between their 16S rRNA sequences. The type strain and koala isolates of C. pecorum were also found to be very similar to each other, possessing two different 16S rRNA sequences with only one-nucleotide difference. Furthermore, the C. pecorum strains truncated the 16S rRNA molecule by one nucleotide compared to the molecules of the other chlamydial species. This truncation was found to result in loss of a unilaterally bulged nucleotide, an attribute present in all other eubacteria. The phylogenetic structure of the genus Chlamydia was determined by analysis of 16S rRNA sequences. All phylogenetic trees revealed a distinct line of descent of the family Chlamydiaceae built of two main clusters which we denote the C. pneumoniae cluster and the C. psittaci cluster. The clusters were verified by bootstrap analysis of the trees and signature nucleotide analysis. The former cluster contained the human isolates of C. pneumoniae and equine strain N16. The latter cluster consisted of C. psittaci, C. pecorum, and C. trachomatis. The members of the C. pneumoniae cluster showed tight clustering and strain N16 is likely to be a subspecies of C. pneumoniae since these strains also share some antigenic cross-reactivity and clustering of major outer membrane protein gene sequences. C. psittaci and strain N16 branched early out of the respective cluster, and interestingly, their inclusion bodies do not stain with iodine. Furthermore, they also share less reliable features like normal elementary body morphology and plasmid content. Therefore, the branching order presented here is very likely a true reflection of evolution, with strain N16 of the species C. pneumoniae and C. psittaci forming early branches of their respective cluster and with C. trachomatis being the more recently evolved species within the genus Chlamydia.

Animals↗
PubMed1995

Usefulness of omp1 restriction mapping for avian Chlamydia psittaci isolate differentiation.

Sixty-five avian Chlamydia psittaci isolates collected worldwide, including 27 previously characterized reference strains, were analysed by restriction mapping of the major outer membrane protein gene (omp1) obtained after DNA amplification by PCR. They were compared to 2 ruminant isolates, a feline pneumonitis and a guinea pig inclusion conjunctivitis (GPIC) isolate. According to their omp1 restriction patterns, avian strains were heterogeneous in that they exhibited 6 and 4 distinct patterns using AluI and MboII restriction enzymes, respectively, thus defining 7 groups. However, 84% of the studied strains belonged to groups 1 to 4, which share a specific fragment triplet of 411, 282 and 102 base pairs in their AluI digestion patterns. Comparisons with serological classifications showed a strict correlation and allowed further intraserovar differentiation. Furthermore, this classification based upon a single gene (omp1) roughly correlated with the data obtained by RFLP of native DNA and DNA/DNA hybridization studies. There was no host or geographic specificity in the pattern exhibited by these strains. The ruminant, feline pneumonitis and GPIC C. psittaci isolates were clearly distinguished from each other and the avian strains. Moreover, this method was clearly able to identify dubiously designated strains as well as mixtures of isolates within a single sample. In conclusion, this PCR approach based upon omp1 restriction mapping enables the differentiation of avian C. psittaci isolates and can be proposed as a taxonomic and epidemiologic tool.

Animals↗
PubMed1995

Value of screening for oro-pharyngeal Chlamydia trachomatis infection.

AIMS: To determine whether oro-pharyngeal colonisation by Chlamydia trachomatis occurs in patients at risk of genital chlamydia infection; to determine whether screening pharyngeal specimens by polymerase chain reaction (PCR) increases detection of C trachomatis compared with isolation and the immune dot blot test; and to correlate the detection of C trachomatis and Neisseria gonorrhoeae in the pharynx with a history of oro-genital contact. METHODS: Thirteen homosexuals and 11 heterosexuals were included in the study. Urogenital and pharyngeal specimens were tested for C trachomatis and N gonorrhoeae using standard clinical diagnostic procedures. Two different PCR methodologies were also used to detect C trachomatis in the pharyngeal specimens. Results were correlated with the mode of sexual practice. RESULTS: Oro-genital sexual contact was practised by 64.9% (72/111) of heterosexuals in addition to penetrative penovaginal intercourse. Additionally, 62.1% (77/124) of all patients did not use any form of barrier protection. Of those who admitted to oro-genital sexual contact, 17.6% of patients with a genital chlamydial infection and 36.4% of those with genital gonorrhoea also had asymptomatic pharyngeal colonisation. C trachomatis was detected in three of 124 (2.4%) pharyngeal specimens by PCR which were reported as negative by chlamydial culture; one was positive by the immune dot blot test. CONCLUSION: The majority of patients practised unprotected oro-genital contact and significant pharyngeal colonisation by C trachomatis and N gonorrhoeae occurred if genital infection was present. Despite the use of PCR in a population at high risk of sexually transmitted disease, the prevalence of chlamydia in the pharynx was very low. This indicates that transmission of C trachomatis to the oro-pharynx does not pose a serious health risk and that screening of patients for oro-pharyngeal C trachomatis is not worthwhile.

Adolescent↗
PubMed1993

Evidence for Chlamydia pneumoniae of non-human origin.

This paper describes the characterization and taxonomic status of N16, a chlamydial isolate from the respiratory tract of a horse. N16 contains plasmid DNA, has normal elementary body morphology and its inclusions do not stain with iodine. Its major outer-membrane protein (MOMP) gene was completely sequenced and compared with the MOMP genes of Chlamydia pneumoniae, C. psittaci, C. trachomatis and C. pecorum. This analysis revealed that N16 is closely related to the TWAR strain of C. pneumoniae (94.5% and 94.4% DNA homology with TWAR isolates IOL-207 and AR-39 respectively). By comparison, N16 shows between 72.1% and 73.7% DNA homology with C. psittaci strains, 70.9% and 71.1% homology with C. pecorum strains LW613 and 1710S and 69.2% homology with C. trachomatis serotype E. The MOMP gene of N16 shares 93.8% DNA homology with the MOMP gene of a chlamydial isolate KC from the conjunctiva of a koala. Monoclonal antibodies raised to C. pneumoniae IOL-207 and shown to be C. pneumoniae-specific confirmed that N16 was more closely related to C. pneumoniae than to C. psittaci. Thus DNA homology and monoclonal antibody data both suggest that horse chlamydiae, as exemplified by N16, form a new second strain of C. pneumoniae. This species is probably more widespread and diverse than the current literature would suggest.

Amino Acid Sequence↗