PubMed Health⌕ Search

Biomedical subjects

A E Stapleton

Publications and source records attributed to A E Stapleton.

23 records · Page 2Linked to original sources
PubMed1994

Flavonoids can protect maize DNA from the induction of ultraviolet radiation damage.

Diverse flavonoid compounds are widely distributed in angiosperm families. Flavonoids absorb radiation in the ultraviolet (UV) region of the spectrum, and it has been proposed that these compounds function as UV filters. We demonstrate that the DNA in Zea mays plants that contain flavonoids (primarily anthocyanins) is protected from the induction of damage caused by UV radiation relative to the DNA in plants that are genetically deficient in these compounds. DNA damage was measured with a sensitive and simple assay using individual monoclonal antibodies, one specific for cyclobutane pyrimidine dimer damage and the other specific for pyrimidine(6,4)pyrimidone damage.

Anthocyanins↗
PubMed1992

Lack of circumcision increases the risk of urinary tract infection in young men.

OBJECTIVE: To determine whether lack of circumcision increases the risk of urinary tract infection (UTI) in adult men. DESIGN AND SETTING: Retrospective case-control study (1987-1990) at a sexually transmitted disease clinic in Seattle, Wash. PATIENTS: Twenty-six men (median age, 30 years) who had microbiologically confirmed symptomatic UTIs (cases) compared with 52 men (median age, 32 years) who had urinary symptoms but negative urine cultures (controls). MAIN OUTCOME MEASURE: Circumcision status among bacteriuric and nonbacteriuric men. RESULTS: The bacteriuric and nonbacteriuric groups were similar in age, race, sexual activity, and sexual preference. Eight (31%) of the 26 bacteriuric men were uncircumcised compared with 6 (12%) of the 52 nonbacteriuric men (P = .037; odds ratio, 3.4; 95% confidence interval, 1.0 to 11.2). Among 19 patients infected with gram-negative bacilli, 8 (42%) of 19 were uncircumcised vs 6 (12%) of 52 nonbacteriuric men (P = .004; odds ratio, 5.6; 95% confidence interval, 1.6 to 19.4). Escherichia coli was the most common urinary isolate (15 of 26 isolates), and the majority of E coli strains possessed urovirulence determinants, including mannose-resistant hemagglutination (10 of 14 isolates), F fimbriae (11 of 14 isolates), P fimbriae (6 of 14 isolates), hemolysin (10 of 14 isolates), and aerobactin (8 of 14 isolates). Although all 26 bacteriuric men had urethral cultures negative for Chlamydia trachomatis and Neisseria gonorrhoeae, Gram-stained urethral smears showed evidence of urethritis in 17 (68%) of 25 men. CONCLUSIONS: (1) Lack of circumcision increases the risk of UTI in young adult men. (2) The majority of these infections result from urovirulent strains of E coli. (3) Clinically, these infections often produce urethritis as well as UTI.

Adult↗
PubMed1991

CDC55, a Saccharomyces cerevisiae gene involved in cellular morphogenesis: identification, characterization, and homology to the B subunit of mammalian type 2A protein phosphatase.

Microscopic screening of a collection of cold-sensitive mutants of Saccharomyces cerevisiae led to the identification of a new gene, CDC55, which appears to be involved in the morphogenetic events of the cell cycle. CDC55 maps between CDC43 and CHC1 on the left arm of chromosome VII. At restrictive temperature, the original cdc55 mutant produces abnormally elongated buds and displays a delay or partial block of septation and/or cell separation. A cdc55 deletion mutant displays a cold-sensitive phenotype like that of the original isolate. Sequencing of CDC55 revealed that it encodes a protein of about 60 kDa, as confirmed by Western immunoblots using Cdc55p-specific antibodies. This protein has greater than 50% sequence identity to the B subunits of rabbit skeletal muscle type 2A protein phosphatase; the latter sequences were obtained by analysis of peptides derived from the purified protein, a polymerase chain reaction product, and cDNA clones. An extragenic suppressor of the cdc55 mutation lies in BEM2, a gene previously identified on the basis of an apparent role in bud emergence.

Amino Acid Sequence↗
PubMedDate not supplied

Effect of Staphylococcus aureus bacteria and bacterial toxins on meningeal permeability in vitro.

BACKGROUND AND OBJECTIVES: Epidural catheterization is associated with a significant bacterial colonization rate and occasionally frank infection. During epidural space infection, decreased analgesia despite increased epidural opioid doses has been described. One possible explanation for this observation is that bacterial infection decreases meningeal permeability. The purpose of the study was to determine whether Staphylococcus aureus bacteria, the most common organism causing epidural space infection, or S. aureus toxins alter meningeal permeability. METHODS: Spinal meninges of M. nemestrina monkeys were mounted in a previously established in vitro diffusion cell model and exposed to S. aureus toxins A, B, and F. Simultaneous transmeningeal fluxes of mannitol and sufentanil were measured before and after toxin exposure and compared to controls. In a second series of experiments, diffusion cells were inoculated with live S. aureus bacteria in suspension and the permeability of sufentanil was investigated. RESULTS: Staphylococcus aureus toxin-A increased the transmeningeal flux of mannitol but not sufentanil. Toxins B and F did not alter the meningeal permeability of either drug. Inoculation with live S. aureus bacteria increased the transmeningeal flux of sufentanil by 115+/-21% (P = .032). CONCLUSIONS: These data demonstrate that S. aureus alpha-toxin and live S. aureus bacteria can increase meningeal permeability. Thus, clinical observations of decreased epidural analgesia in the face of bacterial infection cannot be explained by decreased meningeal permeability.

Animals↗