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Biomedical subjects

A Cochran

Publications and source records attributed to A Cochran.

At least 19 recordsLinked to original sources
PubMed2005

Deep Impact: observations from a worldwide Earth-based campaign.

On 4 July 2005, many observatories around the world and in space observed the collision of Deep Impact with comet 9P/Tempel 1 or its aftermath. This was an unprecedented coordinated observational campaign. These data show that (i) there was new material after impact that was compositionally different from that seen before impact; (ii) the ratio of dust mass to gas mass in the ejecta was much larger than before impact; (iii) the new activity did not last more than a few days, and by 9 July the comet's behavior was indistinguishable from its pre-impact behavior; and (iv) there were interesting transient phenomena that may be correlated with cratering physics.

Cosmic Dust↗
PubMed2005

Quasielastic 3He(e,e'p)2H reaction at Q2 = 1.5 GeV2 for recoil momenta up to 1 GeV/c.

We have studied the quasielastic 3He(e,e(')p)2H reaction in perpendicular coplanar kinematics, with the energy and the momentum transferred by the electron fixed at 840 MeV and 1502 MeV/c, respectively. The 3He(e,e(')p)2H cross section was measured for missing momenta up to 1000 MeV/c, while the A(TL) asymmetry was extracted for missing momenta up to 660 MeV/c. For missing momenta up to 150 MeV/c, the cross section is described by variational calculations using modern 3He wave functions. For missing momenta from 150 to 750 MeV/c, strong final-state interaction effects are observed. Near 1000 MeV/c, the experimental cross section is more than an order of magnitude larger than predicted by available theories. The A(TL) asymmetry displays characteristic features of broken factorization with a structure that is similar to that generated by available models.

Journal Article↗
PubMed2005

Measurement of the 3He(e,e'p)pn reaction at high missing energies and momenta.

Results of the Jefferson Lab Hall A quasielastic 3He(e,e'p)pn measurements are presented. These measurements were performed at fixed transferred momentum and energy, q=1502 MeV/c and omega=840 MeV, respectively, for missing momenta p(m) up to 1 GeV/c and missing energies in the continuum region, up to pion threshold; this kinematic coverage is much more extensive than that of any previous experiment. The cross section data are presented along with the effective momentum density distribution and compared to theoretical models.

Journal Article↗
PubMed2004

Angular distributions for (3,4)(Lambda)H bound states in the (3,4)He(e,e(')K+) reaction.

The (3,4)(Lambda)H and (4)(Lambda)H hypernuclear bound states have been observed for the first time in kaon electroproduction on (3,4)He targets. The production cross sections have been determined at Q(2)=0.35 GeV2 and W=1.91 GeV. For either hypernucleus the nuclear form factor is determined by comparing the angular distribution of the (3,4)He(e,e(')K+)(3,4)(Lambda)H processes to the elementary cross section 1H(e,e K+)Lambda on the free proton, measured during the same experiment.

Journal Article↗
PubMed2004

Increased expression of MAIL, a cytokine-associated nuclear protein, in the prodromal stage of black walnut-induced laminitis.

REASONS FOR PERFORMING STUDY: The mediators and signalling cascades important in the initiation of laminitis remain unclear. We therefore wanted to explore the genes and overall signalling mechanisms that play an important role in the developmental stage of laminitis. OBJECTIVE: To use a broad genomic screening technique to identify novel genes that are differentially regulated in the equine lamellae during the developmental period of laminitis. METHODS: Differential mRNA display (DRD) was performed to discover regulated genes, and real-time quantitative polymerase chain reaction (RT-qPCR) was then used to evaluate lamellar mRNA levels of a regulated gene (MAIL) and mediators related to that gene (IL-1beta and IL-6) in control horses (n = 5) and horses administered black walnut extract (BWE; n = 5). RESULTS: Using DRD, MAIL was identified as a regulated gene. RT-qPCR indicated a 4-fold increase in expression of the MAIL mRNA in BWE lamellae compared to controls. A 30-fold increase in IL-1beta, and a 160-fold difference in IL-6 mRNA expression was present in BWE lamellae. Differences in MAIL, IL-1beta and IL-6 mRNA expression were statistically significant between groups (P < 0.05). CONCLUSIONS AND POTENTIAL RELEVANCE: The data strongly support a role for inflammatory cytokines in the developmental stages of laminitis, possibly inducing the vascular and metabolic alterations reported to occur in the affected digit. These results potentially support the use of anti-inflammatory drugs in horses at risk of laminitis, and warrant further investigation of the link between systemic disease processes associated with laminitis and the reported digital inflammation.

Adaptor Proteins, Signal Transducing↗
PubMed2003

Polarization transfer in the 4He(e-->,e'p-->)3H reaction up to Q2=2.6 (GeV/c)2.

We have measured the proton recoil polarization in the 4He(e-->,e(')p-->)4H reaction at Q(2)=0.5, 1.0, 1.6, and 2.6 (GeV/c)(2). The measured ratio of polarization transfer coefficients differs from a fully relativistic calculation, favoring the inclusion of a medium modification of the proton form factors predicted by a quark-meson coupling model. In addition, the measured induced polarizations agree reasonably well with the fully relativistic calculation indicating that the treatment of final-state interactions is under control.

Journal Article↗
PubMed2002

1-3 connectivity composite material made from lithium niobate and cement for ultrasonic condition monitoring at elevated temperatures.

We have designed, manufactured and tested a piezoelectric composite material to operate at temperatures above 400 degrees C. The material is a 1-3 connectivity composite with pillars of Z-cut lithium niobate in a matrix of alumina cement. The composite material produced shorter pulses than a monolithic plate of lithium niobate and remained intact upon cooling. Results are presented from room temperature and high temperature testing. This material could be bonded permanently to a test object, making it possible to carry out condition monitoring over an extended period. A new excitation method was also developed to enable remote switching between array elements.

Journal Article↗
PubMed2001

Measurement of the high energy two-body deuteron photodisintegration differential cross section.

The first measurements of the d(gamma,p)n differential cross section at forward angles and photon energies above 4 GeV were performed at the Thomas Jefferson National Accelerator Facility (JLab). The results indicate evidence of an angular dependent scaling threshold. Results at straight theta(cm) = 37 degrees are consistent with the constituent counting rules for E(gamma) greater, similar 4 GeV, while those at 70 degrees are consistent with the constituent counting rules for E(gamma) greater, similar 1.5 GeV.

Journal Article↗
PubMed2001

Structure-function analysis of a phage display-derived peptide that binds to insulin-like growth factor binding protein 1.

Highly structured, peptide antagonists of the interaction between insulin-like growth factor 1 (IGF-I) and IGF binding protein 1 (IGFBP-1) have recently been discovered by phage display of naïve peptide libraries [Lowman, H. B., et al. (1998) Biochemistry 37, 8870--8878]. We now report a detailed analysis of the features of this turn-helix peptide motif that are necessary for IGFBP-1 binding and structural integrity. Further rounds of phage randomization indicate the importance of residues contributing to a hydrophobic patch on one face of the helix. Alanine-scanning substitutions confirm that the hydrophobic residues are necessary for binding. However, structural analysis by NMR spectroscopy indicates that some of these analogues are less well folded. Structured, high-affinity analogues that lack the disulfide bond were prepared by introducing a covalent constraint between side chains at positions i and i + 7 or i + 8 within the helix. Analogues based on this scaffold demonstrate that a helical conformation is present in the bound state, and that hydrophobic side chains in this helix, and residues immediately preceding it, interact with IGFBP-1. By comparison of alanine scanning data for IGF-I and the turn-helix peptide, we propose a model for common surface features of these molecules that recognize IGFBP-1.

Alanine↗
PubMed2000

Don't ask, don't tell: the incontinence conspiracy.

Don't ask, don't tell is the attitude of both patients and doctors toward symptoms of urinary incontinence (UI). This has serious fiscal implications for managed care, because the consequences of not treating the condition increase the annual cost of care by an estimated $3,941 per individual. Behavioral treatments have clinical efficacy of 87 percent, and should be tried first, according to the clinical practice guidelines published by the Agency for Health Care Policy and Research. Attitudes about the condition, and historical and current interventions, are discussed.

Adult↗
PubMed1999

Current management of AIDS and related opportunistic infections.

Significant changes in acquired immunodeficiency syndrome (AIDS) epidemiology and AIDS treatment strategies have emerged in the 17 years since the first case of this disease was reported. In the United States, the human immunodeficiency virus (HIV) is now primarily acquired through heterosexual relationships and intravenous drug use. As a result, dramatic increases in the number of AIDS cases in the female, African American, and Hispanic populations are evident. Treatment strategies now focus on maximal viral suppression and preventing drug resistance. Advances in anti-retroviral therapy and chemoprophylaxis of opportunistic infections have increased the long-term survival of AIDS patients by 10 to 20 years. However, despite abundant research and advances in medical care, AIDS continues to be a devastating epidemic worldwide.

AIDS-Related Opportunistic Infections↗
PubMed1998

Response to urinary incontinence by older persons living in the community.

PURPOSE: To investigate the responses to urinary incontinence (UI) of older persons living in the community. DESIGN: Detailed interviews were completed on a sample of 42 independent, community-dwelling persons who were at least 60 years of age. Nineteen participants reported UI, and their experiences are reported in detail. SETTING AND SUBJECTS: Subjects were recruited from 3 sources: volunteers who acknowledged having UI, those with known UI who were invited by their doctors to participate, and those who selected "Loss of bladder control" in a 20-card sort of common ailments. All interviews were conducted in a private setting at a seniors center or at participants' church or home. INSTRUMENTS: Twenty cards with a common ailment printed in large type and an interview schedule with questions relating to the ailment selected as having the most impact were used; demographic data were collected on a standardized form. METHODS: Interviews were recorded on audiotape and lasted from 20 to 60 minutes. These recordings were analyzed for themes with use of Ethnography software. MAIN OUTCOME MEASURES: Demographic and other data from the interview schedule were tabulated. The communication style of the 19 subjects with UI was analyzed to determine how freely they spoke about problems with bladder control to family and friends and their sources of information for managing urinary leakage. Analysis was done both by the researcher and a faculty member; an interrater reliability of 1.00 was achieved. RESULTS: There was little difference in the self-rating of health for those with or without UI. Subjects recruited by letters sent to doctors' patients ranked the impact of loss of bladder control higher than other subjects did. Of the 19 subjects with UI, 10 spoke freely to family and friends, but 9 seldom discussed the subject--and then only to a family member. Four of the 9 with a closed communication style reported no current source of information about UI or its management. CONCLUSION: Though UI had a major effect on the lives of these subjects, they were more willing to admit having "loss of bladder control" than "urinary incontinence." Communication style is related to prior sources of information about UI, but not its perceived impact on health. This relationship helps to determine the teaching methods that are most likely to influence elderly persons with UI who have either on open or closed communication style.

Activities of Daily Living↗
PubMed1998

Dampening of the cortisol response to handling at 3 months in human infants and its relation to sleep, circadian cortisol activity, and behavioral distress.

The decrease in responsiveness of the hypothalamic-pituitary-adrenocortical (HPA) system is marked over the first months of life. Seventy-eight healthy infants (44 girls), 7 to 15 weeks old, were given a laboratory mock physical examination. Salivary cortisol samples were collected pre- and postexamination and at home. Behavioral state during the examination and home sleep/wake activity were measured. Subjects younger than 11 weeks showed an increase in pre- to postexamination cortisol, while older subjects did not. Further, there was no decrease in behavioral distress to the examination with age. Infants who showed an early- morning peak (EMP) in home cortisol levels were significantly older and were likely to be those who slept through the night. However, the presence of an EMP was not associated with a lack of cortisol response to the examination. The decrease in cortisol responsiveness witnessed around the age of 3 months is presumably due to other processes associated with age, and not with the expression of the day-night rhythm in basal cortisol.

Arousal↗
PubMed1997

Developing careers despite an environment of downsizing: what worked for one nurse.

My patients are achieving a higher level of success, now that I have used these steps. My compensation is better than when, like a piano teacher, I was going to people's homes to give lessons. And because continence includes related health issues, I am doing the health education I have always enjoyed but seldom had time to do when working in acute care settings. Although this application dealt with urinary incontinence, the steps can be applied to many other health conditions and their management. What would you really like to do professionally? Write down everything you can think of, and circle the most likely, or use "right brain clustering," and you will be surprised what you can come up with. It might even be something you can get paid well for doing.

Career Mobility↗
PubMed1993

Intraoperative lymphatic mapping and selective cervical lymphadenectomy for early-stage melanomas of the head and neck.

PURPOSE: We developed intraoperative lymphatic mapping with selective lymphadenectomy (SLND) to identify micrometastatic spread of cutaneous melanoma to regional lymph nodes. This study was undertaken to assess the sensitivity and specificity of our technique in patients with clinical stage I (CS-I) melanoma of the head or neck. PATIENTS AND METHODS: Seventy-two CS-I melanoma patients underwent intraoperative lymphatic mapping of primary cutaneous melanomas located on the head, neck, or upper chest/back draining to the neck. Key (sentinel) cervical lymph nodes in the regional lymphatic drainage basin were identified, selectively excised during SLND, and examined for microscopic evidence of tumor cells. If these sentinel nodes were tumor-negative, the surgery was concluded; if the sentinel nodes were tumor-positive, all nodes in the drainage basin were removed during en bloc lymphadenectomy (LND). RESULTS: Intraoperative lymphatic mapping identified sentinel nodes in 90% of the regional drainage basins. Fifteen percent of these nodes were tumor-positive, indicating the need for LND. There were no false-negative sentinel nodes, and extended follow-up showed no local nodal recurrences in patients whose sentinel-node histology did not indicate the need for LND. CONCLUSION: Intraoperative lymphatic mapping and SLND is a minimally invasive and highly accurate screening technique for determining which patients with CS-I head and neck melanomas have subclinical node metastases and therefore might benefit from cervical LND.

Adolescent↗