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Biomedical subjects

S A Wright

Publications and source records attributed to S A Wright.

At least 19 recordsLinked to original sources
PubMed2005

Lick Observatory Optical SETI: targeted search and new directions.

Lick Observatory's Optical SETI (search for extraterrestrial intelligence) program has been in regular operation for 4.5 years. We have observed 4,605 stars of spectral types F-M within 200 light-years of Earth. Occasionally, we have appended objects of special interest, such as stars with known planetary systems. We have observed 14 candidate signals ("triple coincidences"), all but one of which are explained by transient local difficulties. Additional observations of the remaining candidate have failed to confirm arriving pulse events. We now plan to proceed in a more economical manner by operating in an unattended drift scan mode. Between operational and equipment modifications, efficiency will more than double.

Astronomical Phenomena↗
PubMed2001

Pantoea agglomerans strain EH318 produces two antibiotics that inhibit Erwinia amylovora in vitro.

Pantoea agglomerans (synonym: Erwinia herbicola) strain Eh318 produces through antibiosis a complex zone of inhibited growth in an overlay seeded with Erwinia amylovora, the causal agent of fire blight. This zone is caused by two antibiotics, named pantocin A and B. Using a genomic library of Eh318, two cosmids, pCPP702 and pCPP704, were identified that conferred on Escherichia coli the ability to inhibit growth of E. amylovora. The two cosmids conferred different antibiotic activities on E. coli DH5alpha and had distinct restriction enzyme profiles. A smaller, antibiotic-conferring DNA segment from each cosmid was cloned. Each subclone was characterized and mutagenized with transposons to generate clones that were deficient in conferring pantocin A and B production, respectively. Mutated subclones were introduced into Eh318 to create three antibiotic-defective marker exchange mutants: strain Eh421 (pantocin A deficient); strain Eh439 (pantocin B deficient), and Eh440 (deficient in both pantocins). Cross-hybridization results, restriction maps, and spectrum-of-activity data using the subclones and marker exchange mutants, supported the presence of two distinct antibiotics, pantocin A and pantocin B, whose biosynthetic genes were present in pCPP702 and pCPP704, respectively. The structure of pantocin A is unknown, whereas that of pantocin B has been determined as (R)-N-[((S)-2-amino-propanoylamino)-methyl]-2-methanesulfonyl-s uccina mic acid. The two pantocins mainly affect other enteric bacteria, based on limited testing.

Anti-Bacterial Agents↗
PubMed2001

Cost effectiveness of three arbovirus surveillance methods in northern California.

We compared the cost effectiveness of enzootic arbovirus surveillance in northern California by antibody detection in sentinel chickens, virus isolation from mosquitoes, and antibody detection in wild avian hosts. Total and annual recurring costs were determined for each method based on estimated personnel and actual material and travel costs for biweekly surveillance at 3 sites in the Sacramento Valley from May 1 through mid-October 1997 and 1998. Serologic detection of antibodies in wild birds was the most expensive method. Total costs associated with sentinel chickens and mosquitoes combined were less than half of those for the wild bird program. Recurring annual costs for the wild bird and mosquito methods were only slightly less than expenses for those methods during the 1st year of operation, which included nonrecurring setup costs. Recurring costs for sentinel chickens were reduced approximately 40% from total costs during the 1st year of the program and were <14% of recurring costs for wild bird serology. Exceptions and caveats of our analysis are discussed. When considering data from a companion paper on detection of enzootic virus transmission using the 3 methods, we concluded that the current system that combines sentinel chickens and virus isolation from mosquitoes is the most cost-effective and efficient surveillance program and should be retained. Future research efforts should investigate the costs and surveillance efficiency of modifications in the frequency of specimen collection and the placement of chicken flocks and mosquito traps.

Animals↗
PubMed2000

Ecology of Borrelia burgdorferi in ticks (Acari: Ixodidae), rodents, and birds in the Sierra Nevada foothills, Placer County, California.

This study examined the prevalence of Borrelia burgdorferi Johnson, Schmid, Hyde, Steigerwalt & Brenner in host-seeking adult and nymphal Ixodes pacificus Cooley & Kohls and estimated the I. pacificus infestation and B. burgdorferi infection of rodent and avian hosts in the western Sierra Nevada foothills of northern California. Additionally, we identified species likely to participate in an enzootic cycle for B. burgdorferi in this yellow pine transition habitat. Evidence of infection with B. burgdorferi was identified in 7.3 and 5.4% of host-seeking I. pacificus adults and nymphs, respectively. Mean numbers of I. pacificus observed on rodents were 1.15 for Neotoma fuscipes Baird and 0.18 for Peromyscus spp. One of 104 ear punch tissues obtained from woodrats and none from 49 Peromyscus spp. yielded B. burgdorferi. A total of 291 collected birds representing 34 species had a mean of 0.27 I. pacificus per bird. The mean I. pacificus infestation of ground-dwelling birds was 2.5 ticks per bird. Forty-nine of 92 (53%) blood smears collected from birds were reactive to a B. burgdorferi specific antibody. This study presents the identification of a B. burgdorferi-like spirochete in birds in western North America. The tick burden and spirochete infection of birds suggests that birds may be involved in a local B. burgdorferi enzootic cycle and likely participate in the transport of ticks and spirochetes to other locations while rodents from this site do not appear to be major contributors.

Animals↗
PubMed1999

Bivariate analysis of the p53 pathway to evaluate Ad-p53 gene therapy efficacy.

BACKGROUND: Gene therapy of human tumors with adenovirus vectors presents a clinical research challenge and a potential opportunity in cancer therapy. One of the research challenges is that endpoints like tumor reduction, time to recurrence, and survival do not provide information about whether a potential therapeutic infects the targeted cells or whether the transferred gene functions or induces a cellular response. Therefore, a flow cytometric approach was developed for a wildtype, p53 encoding adenoviral vector (Ad-p53) that provides (1) the relative level of p53 transferred by p53 immunoreactivity, (2) mdm2 immunoreactivity as an assay of p53 activity, and (3) estimates of the percentage of infected cells by dual parameter analysis (p53 versus mdm2). METHODS: Three prostate cancer cell lines (PC-3, LNCaP, DU 145) that are null, wild-type, and mutant for p53, respectively, and two ovarian cancer cell lines (PA1, MDAH 2774) that are wild-type and mutant for p53, respectively, were tested for immunoreactivity and lack of cross-reactivity with the monoclonal antibodies, DO-7 (anti-p53) and IF2 (anti-mdm2). Optimal dual staining conditions for a flow cytometric assay employing saturating levels of antibody were developed and tested by infection of PC-3, PA1, and MDAH 2774 with Ad-p53 or a control virus, Ad-luc. Dual staining with DO-7 and propidium iodide was used to determine any biological effect of the transferred gene. RESULTS: Neither DO-7 nor IF2 showed appreciable cross-reactions by Western blot analysis of representative prostate or ovarian cell lines. By flow cytometric titration, DO-7 appears to be a high avidity antibody (saturation staining of 10(6) DU 145 cells with 0.5ug) whereas IF2 appears less so (optimum signal to noise ratio at 1ug/10(6) cells). Infection with Ad-p53 was detected at 6 to 48 hours post infection as a uniform relative increase in p53 levels over background p53 levels. Coincident increases in mdm2 immunoreactivity were also detected. DNA content measurements of PA1 and MDAH 2774 cells indicated that G1 arrest and/or apoptosis occurred subsequent to Ad-p53 infection. p53 and mdm2 levels and DNA content distributions for Ad-luc infected cells were equivalent to uninfected cells. CONCLUSIONS: A flow cytometric approach to measure the efficacy of an Ad-p53 gene therapy vector was developed that detects not only the gene transferred but also the activity of the transferred gene product.

Adenoviridae↗
PubMed1998

Language differences in interpretation of breast cancer health messages.

BACKGROUND: Little is known about how women interpret terminology used in breast cancer messages. The authors assessed the understanding of common cancer terms and whether understanding differed by language of interview. METHODS: In interviews, low-income women 50 years old or older were asked open-ended questions about the meanings of specific terms and phrases in commonly used health messages. RESULTS: Of 232 completed interviews, 167 were conducted in English and 65 in Spanish. Both English- and Spanish-speaking women poorly understood the terms "risk factors," "at risk," and "cancer." Spanish speakers were less likely to provide technical definitions of "diagnosed" and "mammogram" and had different interpretations of several cancer terms compared with English speakers. CONCLUSIONS: Cancer terms mean different things to English and Spanish speakers. Client education could be vastly improved if these cultural differences in interpretation were addressed.

Aged↗
PubMed1998

Infestation of the southern alligator lizard (Squamata: Anguidae) by Ixodes pacificus (Acari: Ixodidae) and its susceptibility to Borrelia burgdorferi.

To investigate the reservoir potential of the southern alligator lizard, Elgaria multicarinata (Blainville), for the Lyme disease spirochete, Borrelia burgdorferi Johnson, Schmid, Hyde, Steigerwalt & Brenner, 14 lizards were collected from 1 county on each side of the northern Central Valley of California. Seven animals were collected from a Placer County site (Drivers Flat) and a Yolo County site (Cache Creek) where B. burgdorferi had been isolated previously from Ixodes pacificus Cooley & Kohls. Overall, the mean abundance of I. pacificus on all 14 lizards was 34.1 (range, 3-63) for larvae and 11.0 (range, 1-28) for nymphs. In captivity, field-attached I. pacificus larvae and nymphs required, on average, 12.6 (range, 1-37) and 14.4 (range, 5-44) d to feed to repletion, respectively. The prevalence of B. burgdorferi infection in host-seeking I. pacificus nymphs was 1.4% in Cache Creek Canyon and 9.9% in Drivers Flat. Attempts to isolate spirochetes from lizard blood or ticks that had fed on lizards and subsequently molted were unsuccessful as were efforts to cultivate spirochetes in lizard sera. These data suggest that the southern alligator lizard is not a competent reservoir for B. burgdorferi, although it is an important host for I. pacificus subadults.

Animals↗
PubMed1997

Changes in surfactant protein gene expression in a neonatal rabbit model of hyperoxia-induced fibrosis.

Lung injuries, including bronchopulmonary dysplasia, alter the surfactant system. We developed a newborn rabbit model of acute, followed by chronic, hyperoxic injury to study surfactant protein (SP) gene expression. Initial litters were exposed to >95% O2 until 50% died (LD50; 7-11 days old). Subsequent litters were exposed to >95% O2 for 8 days, followed by 60% O2 until 22-36 days. Controls were exposed to room air. LD50 animals displayed acute pulmonary inflammation, edema, protein leak, and surfactant dysfunction. These changes resolved, and fibrosis developed by 22 days. Whole lung SP-A mRNA expression (measured by membrane hybridization) was twice control levels at 4 days of >95% O2, with specific elevations in terminal bronchioles and type II cells at 4 days and the LD50 by in situ hybridization. Whole lung SP-B and SP-C mRNA were unchanged from control throughout exposure. However, in situ hybridization showed elevations in SP-B and SP-C mRNA in type II cells in inflamed areas at the LD50. SP mRNA alterations resolved by 22-36 days. The surfactant system recovers from acute hyperoxic injury, despite continued 60% O2 exposure.

Acute Disease↗
PubMed1992

The contribution of vascular endothelial xanthine dehydrogenase/oxidase to oxygen-mediated cell injury.

The conversion of xanthine dehydrogenase (XDH) to xanthine oxidase (XO) and the reaction of XO-derived partially reduced oxygen species (PROS) have been suggested to be important in diverse mechanisms of tissue pathophysiology, including oxygen toxicity. Bovine aortic endothelial cells expressed variable amounts of XDH and XO activity in culture. Xanthine dehydrogenase plus xanthine oxidase specific activity increased in dividing cells, peaked after achieving confluency, and decreased in postconfluent cells. Exposure of BAEC to hyperoxia (95% O2; 5% CO2) for 0-48 h caused no change in cell protein or DNA when compared to normoxic controls. Cell XDH+XO activity decreased 98% after 48 h of 95% O2 exposure and decreased 68% after 48 h normoxia. During hyperoxia, the percentage of cell XDH+XO in the XO form increased to 100%, but was unchanged in air controls. Cell catalase activity was unaffected by hyperoxia and lactate dehydrogenase activity was minimally elevated. Hyperoxia resulted in enhanced cell detachment from monolayers, which increased 112% compared to controls. Release of DNA and preincorporated [8-14C]adenine was also used to assess hyperoxic cell injury and did not significantly change in exposed cells. Pretreatment of cells with allopurinol for 1 h inhibited XDH+XO activity 100%, which could be reversed after oxidation of cell lysates with potassium ferricyanide (K3Fe(CN)6). After 48 h of culture in air with allopurinol, cell XDH+XO activity was enhanced when assayed after reversal of inhibition with K3Fe(CN)6, and cell detachment was decreased. In contrast, allopurinol treatment of cells 1 h prior to and during 48 h of hyperoxic exposure did not reduce cell damage. After K3Fe(CN)6 oxidation, XDH+XO activity was undetectable in hyperoxic cell lysates. Thus, XO-derived PROS did not contribute to cell injury or inactivation of XDH+XO during hyperoxia. It is concluded that endogenous cell XO was not a significant source of reactive oxygen species during hyperoxia and contributes only minimally to net cell production of O2- and H2O2 during normoxia.

Animals↗