Biomedical subjects

J Alexander

Publications and source records attributed to J Alexander.

At least 19 recordsLinked to original sources

PubMed2006

Dense-medium modifications to jet-induced hadron pair distributions in Au+Au collisions at sqrt s NN=200 GeV.

Azimuthal correlations of jet-induced high-p(T) charged hadron pairs are studied at midrapidity in Au+Au collisions at sqrt[s(NN)]=200 GeV. The distribution of jet-associated partner hadrons (1.0<p(T)<2.5 GeV/c) per trigger hadron (2.5<p(T)<4.0 GeV/c) is found to vary with collision centrality, in both shape and yield, indicating a significant effect of the nuclear collision medium on the jet fragmentation process.

Journal Article↗

PubMed2006

Azimuthal angle correlations for rapidity separated Hadron pairs in d+Au collisions at square root of sNN=200 GeV.

Deuteron-gold (d+Au) collisions at the Relativistic Heavy Ion Collider provide ideal platforms for testing QCD theories in dense nuclear matter at high energy. In particular, models suggesting strong saturation effects for partons carrying small nucleon momentum fraction (x) predict modifications to jet production at forward rapidity (deuteron-going direction) in d+Au collisions. We report on two-particle azimuthal angle correlations between charged hadrons at forward/backward (deuteron/gold going direction) rapidity and charged hadrons at midrapidity in d+Au and p+p collisions at square root of sNN=200 GeV. Jet structures observed in the correlations are quantified in terms of the conditional yield and angular width of away-side partners. The kinematic region studied here samples partons in the gold nucleus with x~0.1 to ~0.01. Within this range, we find no x dependence of the jet structure in d+Au collisions.

Journal Article↗

PubMed2006

Common suppression pattern of eta and pi0 mesons at high transverse momentum in Au + Au collisions at square root S(NN) = 200 GeV.

Inclusive transverse momentum spectra of eta mesons have been measured within p(T) = 2-10 GeV/c at midrapidity by the PHENIX experiment in Au + Au collisions at square root S(NN) = 200 GeV. In central Au+Au the eta yields are significantly suppressed compared to peripheral Au + Au, d + Au, and p + p yields scaled by the corresponding number of nucleon-nucleon collisions. The magnitude, centrality, and p(T) dependence of the suppression is common, within errors, for eta and pi0. The ratio of eta to pi0 spectra at high p(T) amounts to 0.40 < R(eta/pi)0 < 0.48 for the three systems, in agreement with the world average measured in hadronic and nuclear reactions and, at large scaled momentum, in e+e- collisions.

Journal Article↗

PubMed2006

Preschool healthcare utilisation related to home oxygen status.

OBJECTIVE: To determine, in prematurely born children who had bronchopulmonary dysplasia (BPD), if respiratory morbidity, healthcare utilisation, and cost of care during the preschool years were influenced by use of supplementary oxygen at home after discharge from the neonatal intensive care unit. DESIGN: Observational study. SETTING: Four tertiary neonatal intensive care units. PATIENTS: 190 children, median gestational age 27 weeks (range 22-31), 70 of whom received supplementary oxygen when discharged home. INTERVENTIONS: Review of hospital and general practitioner records together with a parent completed respiratory questionnaire. MAIN OUTCOME MEASURES: Healthcare utilisation, cost of care, cough, wheeze, and use of an inhaler. RESULTS: Seventy children had supplementary oxygen at home (home oxygen group), but only one had a continuous requirement for home oxygen beyond 2 years of age. There were no significant differences in the gestational age or birth weight of the home oxygen group compared with the rest of the cohort. However, between 2 and 4 years of age inclusive, the home oxygen group had more outpatient attendances (p = 0.0021) and specialist attendances (p = 0.0023), and, for respiratory problems, required more prescriptions (p<0.0001). Their total cost of care was higher (p<0.0001). In addition, more of the home oxygen group wheezed more than once a week (p = 0.0486) and were more likely to use an inhaler (p<0.0001). CONCLUSIONS: Children with BPD who have supplementary oxygen at home after discharge have increased respiratory morbidity and healthcare utilisation in the preschool years.

Birth Weight↗

PubMed2006

2-Amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) induces genetic changes in murine intestinal tumours and cells with ApcMin mutation.

2-Amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) is one of the mutagenic heterocyclic amines derived from cooked meat. In previous animal studies, spontaneous tumour formation in B6(Min/+) mice was associated with somatic loss of the wild-type Apc+ allele by loss of the entire chromosome 18 or by recombination. The objective of this study was to examine genetic changes caused by PhIP-exposure in a mouse intestinal cell line and in tumours from hybrid mice by keeping track of the chromosomes carrying the two Apc alleles. We transformed the SV40 T-immortalised intestinal epithelial cell line IMCE, derived from the B6(Min/+) mice by exposure to N-OH-PhIP, and studied the effect on Apc status and chromosome 18. Eighteen transformed cultures were obtained and all of them had retained the Apc+ allele. Five of seven transformed cultures were tumorigenic after implantation in nude mice. Chromosomal analysis of these five cultures and the parent IMCE cell line showed that the IMCE cells were near-tetraploid with an average of 77 chromosomes/cell, while the tumorigenic cell cultures were all triploid to hyper-triploid with a range of 61-69 chromosomes/cell. The number of copies of chromosome 18 was about four in the IMCE line and this copy number was retained in the transformed lines derived from IMCE. Changes in chromosome 18 and Apc during tumour development in vivo were examined in spontaneously formed and PhIP-induced intestinal tumours from two hybrid mice strains, i.e. B6(Min/+) - a murine FAP model - crossed with either AKR/J or A/J. We evaluated the allelic status of Apc, and the heterogenic microsatellite markers D18Mit19 and D18Mit4, located at the upper and lower ends of chromosome 18, respectively. In tumours from untreated animals, instability in the D18Mit19 and Apc was observed. Upon PhIP exposure, the B6(Min/A+) hybrid mouse tumours differed distinctly in genetic profile from those obtained from untreated animals and we detected three genetically different tumour groups, all of which had apparently retained Apc+. One group had allelic balance between the Apc(Min) and Apc+, the second had allelic imbalance between the Apc and D18Mit4 alleles, indicative of chromosomal stability in the first group and instability in the lower end of chromosome 18 in the second group, respectively. The third group showed variable allelic status of the three markers. A similar change in genetic profile was also seen in intestinal tumours of PhIP-exposed B6(Min/AKR+) hybrid mice, but it was less pronounced. Chromosomal breaks and/or recombinational events could be alternative explanations for the observed allelic imbalances in chromosome 18 markers in intestinal tumours from PhIP-exposed mice.

Allelic Imbalance↗

PubMed2006

Single electrons from heavy-flavor decays in collisions at.

The invariant differential cross section for inclusive electron production in p+p collisions at [FORMULA: SEE TEXT] has been measured by the PHENIX experiment at the BNL Relativistic Heavy Ion Collider over the transverse momentum range 0.4<or=pT<OR=5.0 GeV/c in the central rapidity region ([FORMULA: SEE TEXT]). The contribution to the inclusive electron spectrum from semileptonic decays of hadrons carrying heavy flavor, i.e., charm quarks or, at high , bottom quarks, is determined via three independent methods. The resulting electron spectrum from heavy-flavor decays is compared to recent leading and next-to-leading order perturbative QCD calculations. The total cross section of charm quark-antiquark pair production is determined to be [FORMULA: SEE TEXT].

Journal Article↗

PubMed2006

Nuclear modification of electron spectra and implications for heavy quark energy loss in Au+Au collisions at [FORMULA: SEE TEXT].

The PHENIX experiment has measured midrapidity ([FORMULA: SEE TEXT]) transverse momentum spectra ([FORMULA: SEE TEXT]) of electrons as a function of centrality in Au+Au collisions at [FORMULA: SEE TEXT]. Contributions from photon conversions and from light hadron decays, mainly Dalitz decays of pi0 and eta mesons, were removed. The resulting nonphotonic electron spectra are primarily due to the semileptonic decays of hadrons carrying heavy quarks. Nuclear modification factors were determined by comparison to nonphotonic electrons in p+p collisions. A significant suppression of electrons at high pT is observed in central Au+Au collisions, indicating substantial energy loss of heavy quarks.

Journal Article↗

PubMed2006

Measurement of identified and inclusive photon second-harmonic parameter and implications for direct photon production in [FORMULA: SEE TEXT] Au+Au.

The azimuthal distribution of identified pi0 and inclusive photons has been measured in [FORMULA: SEE TEXT] Au+Au collisions with the PHENIX experiment at the Relativistic Heavy-Ion Collider (RHIC). The second-harmonic parameter (nu2) was measured to describe the observed anisotropy of the azimuthal distribution. The measured inclusive photon is consistent with the value expected for the photons from hadron decay and is also consistent with the lack of direct photon signal over the measured pT range 1-6 GeV/c. An attempt is made to extract nu2 of direct photons.

Journal Article↗

PubMed2006

J/psi production and nuclear effects for d + Au and p + p collisions at square root of S(NN) = 200 GeV.

J/psi production in d + Au and p + p collisions at square root of S(NN) = 200 GeV has been measured by the PHENIX experiment at rapidities -2.2 < y < +2.4. The cross sections and nuclear dependence of J/psi production versus rapidity, transverse momentum, and centrality are obtained and compared to lower energy p + A results and to theoretical models. The observed nuclear dependence in d + Au collisions is found to be modest, suggesting that the absorption in the final state is weak and the shadowing of the gluon distributions is small and consistent with Dokshitzer-Gribov-Lipatov-Altarelli-Parisi-based parametrizations that fit deep-inelastic scattering and Drell-Yan data at lower energies.

Journal Article↗

PubMed2006

Supraesophageal reflux: validation of a symptom questionnaire.

OBJECTIVE: To develop and validate a questionnaire for supraesophageal manifestations of reflux (SER) that will facilitate its study in clinical and research settings. STUDY DESIGN: The Supraesophageal Reflux Questionnaire (SERQ) and previously validated Reflux Symptom Index (RSI) were subjected to multiple types of validity testing, including content validity, concurrent validity, reproducibility, and predictive validity. RESULTS: The concurrent validity and reproducibility of both instruments was good to excellent for most items tested. The predictive validity of the SERQ was superior to the RSI when it included the covariates of history of sinusitis, use of over-the-counter antacid medications, age, gender, and body mass index. CONCLUSIONS: The SERQ will serve as both a useful clinical and research tool by offering not only SER symptom information, like the RSI, but also information about the patient's medical history and medication usage that will facilitate use of the SERQ in research protocols. EBM RATING: B-2b.

Antacids↗

PubMed2006

Translation of an experimental oral vaccine formulation into a commercial product.

An effective experimental vaccine may fail to become a therapeutic reality for a number of scientific, regulatory or commercial reasons. In this review, we share some of our personal experiences as University-based researchers and provide an account of some of the problems that we have encountered during preliminary scale-up and assessment of an oral influenza vaccine formulation. Many of the problems we have faced have been non-scientific and related to identifying project-funding sources, finding suitable contract manufacturing companies that are GMP compliant, and protecting intellectual property generated from the scientific studies. The review is intended as a practical guide that will allow other researchers to adopt effective strategies to permit the translation of an effective experimental formulation to a viable commercial product.

Administration, Oral↗

PubMed2006

Distinct phenotypes of obesity-prone AKR/J, DBA2J and C57BL/6J mice compared to control strains.

OBJECTIVE: To characterize and compare three obesity-prone inbred strains, AKR/J, DBA/2J and C57BL/6J, to three control strains, C3H/HeJ, BALB/cByJ and C57L/J, selected based on their normal eating patterns and moderate weight gain on high-calorie diets. METHODS AND PROCEDURES: These six strains were examined at 5 weeks of age while still of normal body weight, and they were maintained for 1 day or 3 weeks on different feeding paradigms with macronutrient diets. Measurements were taken of macronutrient intake, body weight and body fat accrual, circulating hormones and metabolites, and the hypothalamic peptide, galanin. RESULTS: The three control strains each selected a balanced diet with 50% carbohydrate and 15-25% fat when given a choice of macronutrients, and they had similar, normal range of scores for the measures of body weight, adiposity, the hormones, insulin and leptin, and the metabolites, glucose and triglycerides. When compared to this control baseline, the obesity-prone strains with similar total caloric intake to controls selected a diet with significantly more fat (30-40%) and less carbohydrate (<40%). They also had greater adiposity, with the largest differences detected for the AKR/J and DBA/2J strains. These two obesity-prone strains compared to control strains had elevated levels of insulin and leptin. They also had higher triglyceride levels and increased expression and levels of galanin in the hypothalamic paraventricular nucleus. A very different pattern was detected in the obesity-prone C57BL/6J strain, which exhibited a stronger preference for protein as well as fat, normal levels of insulin, leptin and triglycerides, hyperglycemia relative to all other strains, and a small increase in galanin. CONCLUSION: These comparisons to control strains revealed a distinct phenotype in the two obesity-prone strains, AKR/J and DBA/2J, which is very similar to that described in obesity-prone, outbred rats. They also identified a clearly different phenotype in the obesity-prone C57BL/6J strain.

Adipose Tissue↗

PubMed2006

Patients' feelings about ward nursing regimes and involvement in rule construction.

This study compared two acute psychiatric ward nursing regimes, focusing on ward rules as a means of investigating the relationship between the flexibility/inflexibility of the regimes and patient outcomes. Previous studies identified an association between ward rules and patient aggression. A link between absconding and nurses' attitudes towards rule enforcement has also been explored. However, an in-depth exploration of ward rules from the perspective of nurses and patients had not been undertaken previously. The study aimed to discover the content of rules within acute psychiatric wards; to explore patients' responses to the rules; to evaluate the impact of rules and rule enforcement on nurse-patient relationships and on ward events; and to investigate the relationship between ward rules, ward atmosphere and ward design. The relevance of sociological theory emerged from the data analysis. During this process, the results were moved up to another conceptual level to represent the meaning of lived experience at the level of theory. For example, nurses' descriptions of their feelings in relation to rule enforcement were merged as role ambivalence. This concept was supported by examples from the transcripts. Other possible explanations for the data and the connections between them were checked by returning to each text unit in the cluster and ensuring that it fitted with the emergent theory. The design centred on a comparative interview study of 30 patients and 30 nurses within two acute psychiatric wards in different hospitals. Non-participant observations provided a context for the interview data. Measures of the Ward Atmosphere Scale, the Hospital-Hostel Practices Profile, ward incidents and levels of as required (PRN) medication were obtained. The analysis of the quantitative data was assisted by spss, and the qualitative analysis by QSR *NUDIST. Thematic and interpretative phenomenological methods were used in the analysis of the qualitative data. A series of 11 interrelated concepts emerged from an analysis of the data, and a synthesis of the main themes. This paper focuses on the results and recommendations that emerged from the quantitative and qualitative patient data. A further paper will focus on nurses' perceptions of the same topics.

Adult↗

PubMed2006

Ocular toxoplasmosis: in the storm of the eye.

Ocular toxoplasmosis (OT) can occur in the children of mothers infected with Toxoplasma gondii during pregnancy. It is not limited to the congenitally infected, but can also occur following adult-acquired infection or as a result of disease reactivation in immune-compromised and pregnant individuals. Many aspects of immune privilege in the eye, including constitutive TGF-beta expression and reduced MHC class 1 expression, would appear at first to favour parasite survival. Conversely, many of the mechanisms that control parasite multiplication in other anatomical sites, such as nitric oxide expression, IFN-gamma and TNF-alpha, are known to disrupt immune privilege and are associated with ocular damage. Taking into account the opposing needs of limiting parasite multiplication and minimizing tissue destruction we review the pathogenesis of OT in the murine model.

Animals↗

PubMed2006

Cardiovascular disease after menopause: a growing epidemic.

Coronary heart disease (CHD) remains the major cause of mortality in women after menopause. At the time of menopause risk factors change to increase the risk of CHD. Although hormone replacement therapy improves some of these risk factors, no overall cardiovascular benefit has been noted with this therapy. There are parallel twin epidemics occurring in postmenopausal women, one being cardiovascular disease and the other metabolic syndrome, in which there appears to be a connection. Metabolic risk factors such as elevated triglyceride levels, decreased HDL-cholesterol levels and glucose abnormalities have been suggested to portend a greater CHD risk in women than men. Also the inflammatory marker, C reactive protein, appears to modify risk at all levels of the metabolic syndrome. Further studies are needed to determine the best strategy to confront the epidemic of cardiovascular morbidity and mortality in the postmenopausal population.

Cardiovascular Diseases↗

PubMed2005

Measurement of transverse single-spin asymmetries for midrapidity production of neutral pions and charged hadrons in polarized p + p collisions at square root(s) = 200 GeV.

Transverse single-spin asymmetries to probe the transverse-spin structure of the proton have been measured for neutral pions and nonidentified charged hadrons from polarized proton-proton collisions at midrapidity and square root(s) = 200 GeV. The data cover a transverse momentum (pT) range 1.0-5.0 GeV/c for neutral pions and 0.5-5.0 GeV/c for charged hadrons, at a Feynman-x value of approximately zero. The asymmetries seen in this previously unexplored kinematic region are consistent with zero within errors of a few percent. In addition, the inclusive charged hadron cross section at midrapidity from 0.5 < pT < 7.0 GeV/c is presented and compared to next-to-leading order perturbative QCD (pQCD) calculations. Successful description of the unpolarized cross section above approximately 2 GeV/c suggests that pQCD is applicable in the interpretation of the asymmetry results in the relevant kinematic range.

Journal Article↗

PubMed2005

Saturation of azimuthal anisotropy in Au + Au collisions at (square root)s(NN) = 62-200 GeV.

New measurements are presented for charged hadron azimuthal correlations at midrapidity in Au+Au collisions at (square root)s(NN) = 62.4 and 200 GeV. They are compared to earlier measurements obtained at (square root)s(NN) = 130 GeV and in Pb + Pb collisions at (square root)s(NN) = 17.2 GeV. Sizeable anisotropies are observed with centrality and transverse momentum (pT) dependence characteristic of elliptic flow (upsilon2). For a broad range of centralities, the observed magnitudes and trends of the differential anisotropy, upsilon2(pT), change very little over the collision energy range (square root)s(NN) = 62-200 GeV, indicating saturation of the excitation function for upsilon2 at these energies. Such a saturation may be indicative of the dominance of a very soft equation of state for (square root)s(NN) approximately 60-200 GeV.

Journal Article↗

PubMed2005

Centrality dependence of direct photon production in (square root)S(NN) = 200 GeV Au + Au collisions.

The first measurement of direct photons in Au + Au collisions at (square root)S(NN) = 200 GeV is presented. The direct photon signal is extracted as a function of the Au + Au collision centrality and compared to next-to-leading order perturbative quantum chromodynamics calculations. The direct photon yield is shown to scale with the number of nucleon-nucleon collisions for all centralities.

Journal Article↗