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Biomedical subjects

B Barrett

Publications and source records attributed to B Barrett.

At least 19 recordsLinked to original sources

Determination of the pion charge form factor at Q2=1.60 and 2.45 (GeV/c)2.

The 1H(e,e'pi+)n cross section was measured at four-momentum transfers of Q2=1.60 and 2.45 GeV2 at an invariant mass of the photon nucleon system of W=2.22 GeV. The charged pion form factor (F(pi)) was extracted from the data by comparing the separated longitudinal pion electroproduction cross section to a Regge model prediction in which F(pi) is a free parameter. The results indicate that the pion form factor deviates from the charge-radius constrained monopole form at these values of Q2 by one sigma, but is still far from its perturbative quantum chromodynamics prediction.

Journal Article↗

Validated HPLC-MS-MS method for simultaneous determination of atorvastatin and 2-hydroxyatorvastatin in human plasma-pharmacokinetic study.

Cholesterol-reducing statin drugs are the most frequently prescribed agents for reducing morbidity and mortality related to coronary heart disease. In this publication a validated, highly sensitive, and selective isocratic HPLC method is reported for quantitative determination of the major statin drug atorvastatin (ATV) and its metabolite 2-hydroxyatorvastatin (HATV). Detection was performed with an electrospray ionization triple-quadrupole mass spectrometer equipped with an ESI interface operating in positive-ionization mode. Multiple reaction monitoring (MRM) was used for MS-MS detection. The calibration plot was linear in the concentration range 0.10-40.00 ng mL(-1) for both ATV and HATV. Inter-day and intra-day precision and accuracy of the proposed method were characterized by measurement of relative standard deviation (RSD) and percentage deviation, respectively; both were less than 8% for both analytes. The limit of quantitation was 0.02 ng mL(-1) for ATV and 0.07 ng mL(-1) for HATV. The method was used for pharmacokinetic study of ATV and HATV. Pharmacokinetic data for all analytes are also reported.

Anticholesteremic Agents↗

Relations among questionnaire and laboratory measures of rhinovirus infection.

Due to high incidence and quality-of-life impact, upper respiratory infection substantially impacts on population health. To test or compare treatment effectiveness, a well-designed and validated illness-specific quality-of-life instrument is needed. Data reported in the current study were obtained from a trial testing echinacea for induced rhinovirus infection. Laboratory-assessed biomarkers included interleukin (IL)-8, nasal neutrophil count (polymorphonuclear neutrophils (PMN)), mucus weight, viral titre and seroconversion. The questionnaires used included the general health short form (SF)-8 (24-h recall version), the eight-item Jackson cold scale, and the 44-item Wisconsin Upper Respiratory Symptom Survey (WURSS). In total, 399 participants were inoculated with rhinovirus and monitored over 2,088 person-days. Statistically significant associations were found among nearly all variables. Between-questionnaire correlations were: WURSS-Jackson = 0.81; WURSS-SF-8 = 0.62; and Jackson-SF-8 = 0.60. Correlations with laboratory values were as follows: WURSS-mucus weight = 0.53; Jackson-mucus weight = 0.55; WURSS-viral titre = 0.37; Jackson-viral titre = 0.46; WURSS-IL-8 = 0.31; Jackson-IL-8 = 0.36; WURSS-PMN = 0.31; and Jackson-PMN = 0.28. Neither WURSS nor Jackson yielded satisfactory cut-off scores for diagnosis of infection. Symptomatic and biological outcomes of upper respiratory infection are highly variable, with only modest associations. While Wisconsin Upper Respiratory Symptom Survey and Jackson questionnaires both correlate with biomarkers, neither is a good predictor of induced infection. The inclusion of functional and quality-of-life items in the Wisconsin Upper Respiratory Symptom Survey does not significantly decrease the strength of association with laboratory-assessed biomarkers.

Adult↗

Echinacea for preventing and treating the common cold.

BACKGROUND: Preparations of the plant Echinacea (family Compositae) are widely used in some European countries and in North America for common colds. Most consumers and physicians are not aware that products available under the term Echinacea differ appreciably in their composition, mainly due to the use of variable plant material, extraction methods and addition of other components. OBJECTIVES: The objective of this review was to assess whether there is evidence that Echinacea preparations are 1) more effective than no treatment; 2) more effective than placebo; 3) similarly effective to other treatments in A) the prevention and B) the treatment of the common cold. SEARCH STRATEGY: We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library Issue 3, 2005); PubMed (1997 to April 2005), EMBASE (1998 to June 2005), AMED (to August 2005), Centre for Complementary Medicine Research (in Munich) (1988 to May 2005), contacted experts, and screened references of reviews. SELECTION CRITERIA: We included randomized controlled trials that compared mono-preparations of Echinacea with a placebo, no treatment, or another treatment for the prevention or treatment of common colds. Trials on combinations of Echinacea and other herbs were excluded. DATA COLLECTION AND ANALYSIS: For all studies, at least two authors independently assessed eligibility and trial quality, and extracted data. Outcomes of interest in prevention trials were: numbers of individuals with one or more colds, and severity and duration of colds; and in treatment trials: total symptom scores, nasal symptoms, and duration of colds. MAIN RESULTS: Sixteen trials including a total of 22 comparisons of an Echinacea preparation and a control group (19 with placebo, 2 with no treatment, 1 with another herbal preparation) met the inclusion criteria. All trials except one were described as double-blind. The majority had reasonable to good methodological quality. Three comparisons investigated prevention of colds and 19 comparisons tested treatment of colds. A variety of different Echinacea preparations were used. None of the three comparisons in the prevention trials showed an effect over placebo. Comparing an Echinacea preparation with placebo as treatment, a significant effect was reported in nine comparisons, a trend in one, and no difference in six. More than one trial was available only for preparations based on the aerial parts from Echinacea purpurea (E. purpurea). AUTHORS' CONCLUSIONS: Echinacea preparations tested in clinical trials differ greatly. There is some evidence that preparations based on the aerial parts of Echinacea purpurea might be effective for the early treatment of colds in adults but results are not fully consistent. Beneficial effects of other Echinacea preparations, and for preventative purposes might exist but have not been shown in independently replicated, rigorous randomized trials.

Common Cold↗

Follow-up of patients with contrast-induced nephropathy.

In this chapter, we review the approach to following the patient after contrast is administered. We first discuss the clinical importance of renal injury for if there were no clinically significant consequences of this renal injury, we would have far less concern for the adequacy of follow-up. We next look at markers of renal injury and what tests are used in clinical practice to define contrast-induced nephropathy (CIN). Finally, we discuss the steps that should be taken in those who do develop CIN to limit the impact of the injury and protect them from future adverse events.

Biomarkers↗

Validated HPLC-MS/MS method for simultaneous determination of simvastatin and simvastatin hydroxy acid in human plasma.

Cholesterol lowering statin drugs are the most frequently prescribed agents for reducing morbidity and mortality related to coronary heart disease. This publication presents a validated, highly sensitive and selective isocratic HPLC method for the quantitative determination of the major statin drug simvastatin (SIM) and its metabolite simvastatin hydroxy acid (SIMA). Detection was performed on an electrospray ionization triple quadrupole mass spectrometer equipped with an ESI interface operated in positive and negative ionization mode. The multiple reaction-monitoring mode (MRM) was used to provide MS/MS detection. The linearity for the calibration curve in the concentration range of 0.10-16.00 ng/mL for SIM and 0.10-16.00 ng/mL for SIMA is presented. Inter- and intra-day precision and accuracy of the proposed method were characterized by relative standard deviation (R.S.D.) and percentage deviation, respectively; with both lower than 7% for all analytes. The limit of quantitation was 0.03 ng/mL for SIM and 0.02 ng/mL for SIMA. The devised method was employed in the pharmacokinetic study of SIM and the pharmacokinetic parameters of all analytes are also presented.

Chromatography, High Pressure Liquid↗

Validated HPLC-MS-MS method for determination of azithromycin in human plasma.

A validated, highly sensitive, and selective HPLC method with MS-MS detection has been developed for quantitative determination of azithromycin (AZI) in human Na2EDTA plasma. Roxithromycin (ROX) was used as internal standard. Human plasma containing AZI and internal standard was ultrafiltered through Centrifree Micropartition devices and the concentration of AZI was determined by isocratic HPLC-MS-MS. Multiple reaction monitoring mode (MRM) was used for MS-MS detection. The calibration plot was linear in the concentration range 2.55-551.43 ng mL(-1). Inter-day and Intra-day precision and accuracy of the proposed method were characterized by R.S.D and percentage deviation, respectively; both were less than 8%. Limit of quantification was 2.55 ng mL(-1). The proposed method was used to determine the pharmacokinetic profile of AZI (250-mg tablets).

Anti-Bacterial Agents↗

A microsatellite map of white clover.

The white clover ( Trifolium repens) nuclear genome (n = 2x = 16) is an important yet under-characterised genetic environment. We have developed simple sequence repeat (SSR) genetic markers for the white clover genome by mining an expressed sequence tag (EST) database and by isolation from enriched genomic libraries. A total of 2,086 EST-derived SSRs (EST-SSRs) were identified among 26,480 database accessions. Evaluation of 792 EST-SSR primer pairs resulted in 566 usable EST-SSRs. Of these, 335 polymorphic EST-SSRs, used in concert with 30 genomic SSRs, detected 493 loci in the white clover genome using 92 F1 progeny from a pair cross between two highly heterozygous genotypes--364/7 and 6525/5. Map length, as estimated using the joinmap algorithm, was 1,144 cM and spanned all 16 homologues. The R (red leaf) locus was mapped to linkage group B1 and is tightly linked to the microsatellite locus prs318c. The eight homoeologous pairs of linkage groups within the white clover genome were identified using 96 homoeologous loci. Segregation distortion was detected in four areas (groups A1, D1, D2 and H2). Marker locus density varied among and within linkage groups. This is the first time EST-SSRs have been used to build a whole-genome functional map and to describe subgenome organisation in an allopolyploid species, and T. repens is the only Trifolieae species to date to be mapped exclusively with SSRs. This gene-based microsatellite map will enable the resolution of quantitative traits into Mendelian characters, the characterisation of syntenic relationships with other genomes and acceleration of white clover improvement programmes.

Chromosome Mapping↗

The emerging role of the emergency care practitioner.

OBJECTIVES: To examine the emerging role of the emergency care practitioner (ECP) with comparisons to paramedic practice. Key activities were identified of newly appointed ECPs using qualitative methodology and a qualitative and quantitative comparison of patient treatment was made. METHOD: A constructivist methodology taking account of stakeholder input and drawing upon the constant comparisons of different group's construction of reality. Four practitioners completed reflective patient case studies and adapted patient report forms, which were compared with a second case group of 11 paramedics. In addition individual and focus groups interviews were performed with key stakeholders. RESULTS: In the comparison between ECP and paramedic roles, 331 paramedic incidents were compared with 170 ECP reports. ECPs treated 28% of patients on scene compared with 18% by paramedics (p = 0.007). Fifty per cent of ECPs patients were conveyed compared with 64% of paramedics (p = 0.000). Analysis of the 269 reflective reports and 14 stakeholder interviews revealed four key themes. Firstly, ECPs had a beneficial impact on the deployment of resources, especially relating to non-conveyance. Secondly, their training and education improved their decision making repertoire and developed their confidence for a leadership role. Thirdly, inter-agency collaboration and cooperation was improved, and finally, care benefits were increased especially relating to immediacy of treatment and referral mechanisms. CONCLUSIONS: The results indicate that an investment in the ECP role could be beneficial, however, more work is required to evaluate the development of practice, the quality of care, and cost benefits.

Adolescent↗

Effects of ecdysone agonists on the expression of EcR, USP and other specific proteins in the ovaries of the codling moth (Cydia pomonella L.).

Tebufenozide and methoxyfenozide have been previously shown to significantly reduce fecundity and cause vitellogenin accumulation in hemolymph of the codling moth Cydia pomonella L. In the present study, the effects of these ecdysone agonists, tebufenozide and methoxyfenozide, on the expression of ecdysone receptor (EcR), ultraspiracle protein (USP) and other proteins in the ovaries of C. pomonella L., were investigated at both the translational and/or transcriptional levels with an aim to elucidate the mechanisms by which the fecundity was reduced. Western and Northern blot analyses revealed that the expression of a 65 kDa (p65) EcR, and 60 and 64 kDa (p60 and p64) USP proteins were enhanced by tebufenozide and methoxyfenozide at both transcriptional and translational levels. Northern blot analysis indicated that the p65 EcR protein is encoded by EcRB1 transcript and that the p60 and p64 USP bands were the products of USP-1 transcript. Immunoprecipitation assays demonstrated that both the p60 and p64 USP coprecipitated with the p65 EcR and that p64 was a dominant USP to form complex with EcR. In addition, several other specific proteins were also identified and their expressions affected by the agonists. The data suggest that the ecdysone agonists regulate, via the EcR/USP complex, the expression of these specific proteins that might eventually lead to the inhibition of fecundity in the codling moth.

Animals↗

Medicinal properties of Echinacea: a critical review.

Preparations from Echinacea purpurea are among the most widely used herbal medicines. Most uses of E. purpurea are based on the reported immunological properties. A series of experiments have demonstrated that E. purpurea extracts do indeed demonstrate significant immunomodulatory activities. Among the many pharmacological properties reported, macrophage activation has been demonstrated most convincingly. Phagocytotic indices and macrophage-derived cytokine concentrations have been shown to be Echinacea-responsive in a variety of assays. Activation of polymorphonuclear leukocytes and natural killer cells has also been reasonably demonstrated. Changes in the numbers and activities of T- and B-cell leukocytes have been reported, but are less certain. Despite this cellular evidence of immunostimulation, pathways leading to enhanced resistance to infectious disease have not been described adequately. Several dozen human experiments--including a number of blind randomized trials--have reported health benefits. The most robust data come from trials testing E. purpurea extracts in the treatment for acute upper respiratory infection. Although suggestive of modest benefit, these trials are limited both in size and in methodological quality. Hence, while there is a great deal of moderately good-quality scientific data regarding E. purpurea, effectiveness in treating illness or in enhancing human health has not yet been proven beyond a reasonable doubt.

Adjuvants, Immunologic↗

Identification of chromosomal deficiencies that modify Drosophila mastermind mutant phenotypes.

Mastermind (Mam) is a component of Notch pathway signaling. In combination with the intracellular domain of Notch and Suppressor of Hairless, Mam forms a transcriptional activation complex. We have initiated a genetic approach to identify other loci involved in Mam function. The screen utilizes engineered mutations in Mam that derive from GAL4-UAS-directed expression of dominant negative constructs. When driven at the wing margin, truncated versions of Mam phenocopy Notch pathway mutations. Correlated with these phenotypes is depression of Notch pathway target expression. Strains expressing truncated versions of Mam were tested for genetic interactions with a large collection of chromosomal deficiencies. Genomic segments that enhanced and suppressed the dominant wing phenotype were identified. These regions may contain uncharacterized loci involved in Notch pathway function.

Animals↗

Village-based primary health care in the Central Highlands of Vietnam.

This paper describes the first year of an ongoing village health care and economic development project in the Krong Buk district of Dak Lak province in Vietnam's Central Highlands. The project serves 21 villages with a total population of just over 15,000. Most belong to ethnic minority groups. Physicians from the province capital of Boun Me Thuot were trained by a multi-disciplinary team of American health care workers to be trainers and supervisors of 21 village health care workers (VHWs). Two months later, a VHW from each village was trained in primary and preventive health care by the physician-supervisors. Since this initial training, each VHW has been provided with materials, medicines and monthly supervision by the physician-supervisors. The health care component has been complemented by an economic development project based on a system of small loans. Data from the first year of monthly reports and from a baseline survey are presented in this paper.

Adolescent↗

Cardiovascular disease in patients with chronic kidney disease: getting to the heart of the matter.

The high prevalence of cardiovascular disease (CVD) in patients with kidney disease is well described. This Canadian, multicenter, observational cohort study reports the prevalence and risk factors of CVD associated with kidney disease, in a cohort of patients with established chronic kidney disease (CKD), who are followed-up by nephrologists. This analysis sought to answer 2 questions: (1) in patients with established CKD, are the prevalence and progression of CVD accounted for by conventional or uremia-related risk factors, and (2) to what extent can progression to renal replacement therapy (RRT) be explained by CVD versus traditional risk factors for kidney disease? This study population consists of 313 patients (predominantly men) who had a mean age of 56 years and a mean creatinine clearance of 36 mL/min. Thirty percent were diabetic. The overall prevalence of CVD was 46%, and was independent of severity of kidney dysfunction (P = 0.700). The median follow-up time was 23 months, for a total of 462 patient years. We note the overall incidence of CVD events (new CVD or worsening of CVD) was 47/244 (20%). The best predictors of new CVD events among those without preexisting CVD were diabetes (odds ratio [OR] = 5.35, P = 0.018) and age (OR = 1.26, P = 0.08). In those with preexisting CVD, low diastolic pressure (DP) (OR =.72, P = 0.004) and high triglycerides (OR = 1.48, P = 0.019) at baseline were independent predictors of progression of CVD. We could not determine an independent impact of kidney function on CVD in the overall cohort. Furthermore, we determined that the presence of CVD itself confers an increased risk for progression to RRT (relative risk [RR] = 1.58, P = 0.047), adjusted for kidney function. This is the first in-depth analysis of CVD in a cohort of patients with established chronic kidney disease who are not on dialysis. The question regarding the impact of the altered biology of uremia in contributing to CVD progression remains unanswered, and clearly needs further study. However, the findings do raise the issue of whether aggressive treatment of CVD and risk factors might, in fact, reduce progression to RRT. Further large-scale, observational studies as well as interventional studies are needed to more clearly understand the complex biology of cardiovascular and kidney disease progression.

Age Distribution↗

Complementary and alternative medicine: what's it all about?

A number of health-related interventions--from widespread therapies such as acupuncture, herbal medicine, homeopathy and yoga, to less well-known modalities such as Feldenkrais, iridology, reflexology and reiki--have increasingly come under the general heading of complementary and alternative medicine (CAM). A few, such as biofeedback, chiropractic and physical therapy, are considered conventional by some, alternative by others. Several national surveys estimate that around 40% of the US populace uses a CAM therapy in a given year. While a few people use CAM therapies instead of conventional medicine, the vast majority of CAM users continue to access the official health care system. Many, however, do not discuss their CAM use with their physician. Medical doctors, for their part, are sharply divided on their attitudes toward CAM, with strong advocates and vehement opponents writing and speaking about this issue. CAM therapists are even more diverse, spanning the spectrum from conventional-appearing registered and certified practitioners to iconoclasts promoting anomalous therapies in the place of conventional treatment. The majority, however, both respect and want to work with conventional medicine, as do their patients. Nearly everyone is calling for more and better evidence, and an ever-increasing number of randomized controlled trials and meta-analyses are now appearing in the literature. Over the past few years, a number of calls for "integrated medicine" have been made, and a few attempts at integrating CAM and conventional medicine have been launched. This article reviews these issues, citing our own interview-based work and the relevant literature. Whether the CAM phenomenon represents a short-lived social movement or the beginnings of a radical transformation of medicine has yet to be determined.

Attitude to Health↗

The transport of group 2 capsular polysaccharides across the periplasmic space in Escherichia coli. Roles for the KpsE and KpsD proteins.

The cell surface expression of group 2 capsular polysaccharides involves the translocation of the polysaccharide from its site of synthesis on the inner face of the cytoplasmic membrane onto the cell surface. The transport process is independent of the repeat structure of the polysaccharide, and translocation across the periplasm requires the cytoplasmic membrane-anchored protein KpsE and the periplasmic protein KpsD. In this paper we establish the topology of the KpsE protein and demonstrate that the C terminus interacts with the periplasmic face of the cytoplasmic membrane. By chemical cross-linking we show that KpsE is likely to exist as a dimer and that dimerization is independent of the other Kps proteins or the synthesis of capsular polysaccharide. No interaction between KpsD and KpsE could be demonstrated by chemical cross-linking, although in the presence of both KpsE and Lpp, KpsD could be cross-linked to a 7-kDa protein of unknown identity. In addition, we demonstrate that KpsD is present not only within the periplasm but is also in both the cytoplasmic and outer membrane fractions and that the correct membrane association of KpsD was dependent on KpsE, Lpp, and the secreted polysaccharide molecule. Both KpsD and KpsE showed increased proteinase K sensitivity in the different mutant backgrounds, reflecting conformational changes in the KpsD and KpsE proteins as a result of the disruption of the transport process. Collectively the data suggest that the trans-periplasmic export involves KpsD acting as the link between the cytoplasmic membrane transporter and the outer membrane with KpsE acting to facilitate this transport process.

Bacterial Proteins↗

Cost of outpatient blood transfusion in cancer patients.

PURPOSE: To determine the cost of outpatient RBC transfusion from the provider's perspective at a major urban, academic cancer center. PATIENTS AND METHODS: We retrospectively studied 517 cancer patients with hematologic or solid tumors who received blood during fiscal year 1995 to 1996. A process-flow diagram was developed, and cost and utilization data for 12 months were collected and analyzed. A structured interview process was used to identify all direct and indirect costs from within the inpatient unit, blood bank, and outpatient clinic. Average costs were computed for the entire sample and for specific subgroups. RESULTS: In 1998 dollars, the average cost per RBC unit was $469 for adults and $568 for pediatric cancer patients. Adults and children generally received two and one RBC units per transfusion, respectively. Therefore, the average cost of a two-unit transfusion was $938 for adults. Patients with hematologic tumors required more RBC units (7.1 RBC units per year) at a higher average cost ($512 per RBC unit) than patients with solid tumors (4.7 RBC units per year, $474 per RBC unit). Further variations across tumor types were observed. Overhead, direct material, and direct labor represented 46%, 19%, and 35% of total costs respectively. CONCLUSION: The cost of outpatient RBC transfusions in cancer patients is higher than previously reported, in part because overhead costs and fixed costs might have been underestimated in previous studies. Furthermore, age, tumor type, and geographic variations in the cost of fixed assets and labor have a substantial impact on the cost of blood. The results indicate that the cost-effectiveness of alternatives to transfusions in the management of cancer patients may have been underestimated in the existing literature.

Adult↗