Biomedical subjects

A Proctor

Publications and source records attributed to A Proctor.

At least 19 recordsLinked to original sources

PubMed2005

Regional variation of airway hyperresponsiveness in children with asthma.

Families with asthmatic children were recruited to take part in a multi-centre collaborative study into the genetics of asthma. Detailed phenotypic information was collected on all family members including: lung function, anthropomorphic measurements, response to methacholine challenge, skin prick testing, serum IgE measurements and a detailed nurse-administered questionnaire. Families were eligible for entry into the study if they had two children with a doctor-diagnosis of asthma. Bennett/Twin nebulisers were supplied to each centre from a single source and these were calibrated to determine gravimetric nebuliser output prior to use. Asthmatic probands from each centre had similar degrees of asthma severity and atopy. There was no significant difference in the sex ratios or ages of the probands or numbers of parents with a history of smoking in the families recruited at each centre. However, there was a significant difference in the number of children with airway hyperresponsiveness, with 90% of the North Staffordshire group but only 60% of the Sheffield group having a PC20 of <8 mg/ml for methacholine. This difference highlights the difficulty of using families from different centres in genetic and epidemiological studies.

Asthma↗

PubMed2004

Photochemical production of conjugated linoleic acid from soybean oil.

Conjugated linoleic acid (CLA), an anticarcinogenic compound with numerous other health benefits, is present mainly in dairy and beef lipids. The main CLA isomer present in dairy and beef lipids is cis 9, trans 11 CLA at a 0.5% concentration. The typical minimum human dietary intake of CLA is 10 times less than the 3 g/d suggested requirement that has been extrapolated from animal and cell-line studies. The objectives of this study were to produce CLA isomers from soybean oil by photoisomerization of soybean oil linoleic acid and to study the oxidation status of the oil. Refined, bleached, and deodorized soybean oil with added iodine concentrations of 0, 0.1, 0.25, and 0.5% was exposed to a 100-W mercury lamp for 0 to 120 h. An SP-2560 fused-silica capillary GC column with FID was used to analyze the esterified CLA isomers in the photoisomerized oil. The CLA content of the individual isomers was optimized by response surface methodology. Attenuated total reflectance (ATR)-FTIR spectra in the 3400 to 3600 cm(-1) range and 1H NMR spectra in the 8 to 12 ppm range of the photoisomerized soybean oil were obtained to follow hydroperoxide formation. The largest amount of cis 9, trans 11 CLA isomer in soybean oil was 0.6%, obtained with 0.25% iodine and 84 h of photoisomerization. Lipid hydroperoxide peaks in the ATR-FTIR spectra and aldehyde peaks in the 1H NMR spectra were not observed in the photoisomerized soybean oil, and the spectra were similar to that of fresh soybean oil. This study shows that CLA isomers can be produced simply and inexpensively from soybean oil by photoisomerization.

Hydrogen Peroxide↗

PubMed2002

An improved method for production of silica from rice hull ash.

Rice hull ash (RHA) contains over 60% silica and can be an economically viable raw material for the production of silica based products. A previously published method for producing silica xerogel involved dissolving RHA silica with alkali solution to form sodium silicate solution and subsequently forming silica aquagel by adding hydrochloric acid to lower the pH from 11.8 to 7.0, followed by washing and drying aquagel to form xerogel. The silica xerogel had over 4% sodium as a contaminant. An improved method to produce silica xerogel with lower sodium is described in this study. The improved method involved production of silica aquagel by adding silicate solution to pH 1.5 hydrochloric, citric, or oxalic acid solutions until the pH 4.0 was reached. The aquagel was washed and dried to form silica xerogel. For comparison silica xerogels were also produced at pH 7.0 by the published method. X-ray photoelectron spectroscopy was used to determine the elemental content of silica xerogels. The silica, sodium, carbon and oxygen content of silica xerogels varied depending on the pH and the type of acid used for the production of these xerogels. Silica xerogels produced by the improved method using citric and oxalic acid had sodium content of 0.52% and 0.22%, respectively.

Acids↗

PubMed2001

Improved method for determination of pectin degree of esterification by diffuse reflectance Fourier transform infrared spectroscopy.

An improved method for the determination of pectin degree of esterification (DE) by diffuse reflectance Fourier transform infrared spectroscopy (DRIFTS) was developed. Pectin samples with a range of DE as determined by gas chromatography were used for developing a calibration curve by DRIFTS. A linear relationship between the DE of pectin standards and FTIR peak ratio for ester carboxyl peak area to total carboxyl peak area was found (R(2) = 0.97). Pectin DE of various samples was calculated from the linear fit equation developed by DRIFTS. Accuracy of the DRIFTS method was determined by comparing the DE values of four commercial pectins obtained by DRIFTS methods to the values obtained by the gas chromatography method. Greater precision was obtained for the FTIR measurement of test pectin samples when the ester peak ratio was used relative to the ester peak area.

Calibration↗

PubMed2001

Increasing prevalence of asthma diagnosis and symptoms in children is confined to mild symptoms.

BACKGROUND: The prevalence of childhood asthma is increasing but few studies have investigated trends in asthma severity. We investigated trends in asthma diagnosis and symptom morbidity between an eight year time period in a paired prevalence study. METHODS: All children in one single school year aged 8-9 years in the city of Sheffield were given a parent respondent questionnaire in 1991 and 1999 based on questions from the International Survey of Asthma and Allergy in Children (ISAAC). Data were obtained regarding the prevalence of asthma and wheeze and current (12 month) prevalences of wheeze attacks, speech limiting wheeze, nocturnal cough and wheeze, and exertional symptoms. RESULTS: The response rates in 1991 and 1999 were 4580/5321 (85.3%) and 5011/6021 (83.2%), respectively. There were significant increases between the two surveys in the prevalence of asthma ever (19.9% v 29.7%, mean difference 11.9%, 95% confidence interval (CI) 10.16 to 13.57, p<0.001), current asthma (10.3% v 13.0%, mean difference 2.7%, 95% CI 1.44 to 4.03, p<0.001), wheeze ever (30.3% v 35.8%, mean difference 5.7%, 95% CI 3.76 to 7.56, p<0.001), wheeze in the previous 12 months (17.0% v 19.4%, mean difference 2.5, 95% CI 0.95 to 4.07, p<0.01), and reporting of medication use (16.9% v 20%, mean difference 3.0%, 95% CI 1.46 to 4.62, p<0.001). There were also significant increases in reported hayfever and eczema diagnoses. CONCLUSIONS: Diagnostic labelling of asthma and lifetime prevalence of wheeze has increased. The current 12 month point prevalence of wheeze has increased but this is confined to occasional symptoms. The increased medication rate may be responsible for the static prevalence of severe asthma symptoms. The significant proportion of children receiving medication but reporting no asthma symptoms identified from our 1999 survey suggests that some children are being inappropriately treated or overtreated.

Analysis of Variance↗

PubMed2000

Executive function and verbal working memory in adolescents with closed head injury (CHI).

The relationship between executive function (EF) and working memory (WM) was studied in eight adolescents with closed head injury (CHI) and eight controls, matched for age, gender and socioeconomic status (SES). A cognitive-linguistic test (Scales of Cognitive Ability for Traumatic Brain Injury, SCATBI) was used to group CHI participants by seventy. EF was tested with a measure of daily functioning (Pro-Ex) and WM was tested with a recognition memory task (RMT). When all subject test data were grouped, a positive linear correlation was found for the Pro-Ex and the RMT. A strong-to-moderate positive correlation was found for components of the EF measure and the RMT. Severity of injury influenced test performance for both the EF and WM measures, with a significance between group effects found on the RMT task. Results indicate a relationship between executive function and working memory, severity of injury and test performance and the need to assess EF of CHI adolescents with a measure of daily functioning.

Activities of Daily Living↗

PubMed1998

Automation of data collection for matrix-assisted laser desorption/ionization mass spectrometry using a correlative analysis algorithm.

Automation of data collection in matrix-assisted laser desorption/ionization (MALDI) mass spectrometry using a correlative analysis algorithm is demonstrated. This algorithm was employed to compensate for mass spectral jittering in MALDI data collection (e.g., peak shifts along the m/z axis, signal intensity deviations, etc.). Several important parameters for performing correlative analysis, such as the minimum correlation coefficient to be used and number of mass spectra to acquire prior to correlation, have been investigated and optimized. In addition, the correlation algorithm improved mass resolution of low- and high-molecular-weight compounds by as much as a factor of 4. Signal reproducibility in MALDI quantitative analysis also is improved when correlation is employed for data collection. This data collection algorithm can be used in conjunction with other instrumental optimization programs to allow for fully automated MALDI analysis, which is required for the routine applications carried out in many analytical laboratories.

Algorithms↗

PubMed1998

Rice hull ash and silicic acid as adsorbents for concentration of bacteriocins

A model procedure has been developed for the rapid extraction of five bacteriocins (nisin, pediocin RS2, leucocin BC2, lactocin GI3, and enterocin CS1) from concentrated freeze-dried crude culture supernatants by adsorption onto acid or alkaline rice hull ash (RHA) or silicic acid (SA). Bacteriocins were adsorbed onto RHA or SA by a pH-dependent method and desorbed by decreasing the pH to 2.5 or 3.0 and heating at 90 degreesC for 5 min. The maximum adsorption and optimal pH range for different bacteriocins were as follows: nisin, 97% at pH 7.0; lactocin GI3, 94% at pH 6.0; pediocin RS2, 97% at pH 8.0 to 9.0; leucocin BC2, 88% at pH 9.0; and enterocin CS1, 94% at pH 5.0. The desorption level of lactocin GI3 or enterocin CS1 from the surfaces of both RHA and SA was 94%, while the desorption level of pediocin RS2 and leucocin BC2 was 50% or less. Nisin was desorbed readily from SA (91%) but not from RHA (50% or less). The adsorption of bacteriocins onto RHA and SA increased with the increasing concentration of bacteriocins. Analysis of the desorbed bacteriocins after dialysis and sodium dodecyl sulfate-16% polyacrylamide gel electrophoresis showed a single band that gave a single inhibition zone when overlaid with Lactobacillus plantarum for detection of lactocin GI3, enterocin CS1, and nisin. RHA appears useful for extraction, concentration, and partial purification of the five bacteriocins.

Journal Article↗

PubMed1998

Maintaining patient endurance. The comfort work of trauma nurses.

The purpose of this article is to explicate patterns of comforting that assist the seriously injured patient to endure the pain of injury and subsequent treatments and to remain controlled. The care provided to 67 trauma patients in two trauma centers was videotaped and analyzed using observational methods and linguistic analysis. During painful procedures, when patients exhibited extreme distress, one nurse usually assumed the role of comforter. The nurses used a patterned mode of speech ("comfort talk"), touch, and distinctive posturing behaviors that enabled the patient to endure the agony and maintain control. In this article, the authors describe the comfort work of nursing in emerging situations, further develop the Comfort Talk Register, and describe the concomitant behaviors that facilitate patient endurance. They suggest that the comfort work of nurses in this situation enables patients to endure and reduces shock and posttraumatic stress following trauma care.

Adaptation, Psychological↗

PubMed1996

A quantitative study of in vitro hepatic metabolism of tacrolimus (FK506) using secondary ion and matrix-assisted laser desorption/ionization mass spectrometry.

The identification and simultaneous quantification of Tacrolimus and its hepatic metabolites in baboons has been achieved using matrix-assisted laser desorption/ionization (MALDI) time-of-flight (TOF) mass spectrometry and static secondary-ion mass spectrometry (TOF-SIMS). Little fragmentation, high sensitivity and tolerance to contamination are the major advantages of these methods, allowing facile identification and quantification of metabolites produced in vitro with minor analyte isolation. Based on the MALDI and TOF-SIMS results, seven metabolites have been identified: de-methylated, di de-methylated, hydroxylated, di hydroxylated, de-methylated hydroxylated, dihydrodiol, and di de-methylated hydroxylated. The concentrations of the parent drug and its major metabolites (e.g. de-methylated, di de-methylated) were measured using Rapamycin as an internal standard. The time course of Tacrolimus and its major metabolites as a function of incubation time was calculated. Good correlation between SIMS and MALDI results was obtained.

Animals↗

PubMed1996

Direct quantitative analysis of peptides using matrix assisted laser desorption ionization.

The protocol and various matrices were examined for quantification of biomolecules in both the low ca. 1200 amu and mid mass 6000-12000 amu ranges using an internal standard. Comparative studies of different matrices of MALDI quantitative analysis showed that the best accuracy and standard curve linearity were obtained for two matrices: (a) 2,5-dihydroxybenzoic acid (DHB) combined with a comatrix of fucose and 5-methoxysalicylic acid (MSA) and (b) ferulic acid/fucose. In the low mass range, the quantitative limit was in the 30 fmol range and in the mid mass range the quantitative limit was in the 250 fmol range. Linear response was observed over 2-3 decades of analyte concentration. The relative error of the standard curve slope was 1.3-1.8% with correlation coefficients of 0.996-0.998.The main problem for quantitative measurement was suppression of the signal of the less concentrated component (analyte or internal standard) by the more concentrated component. The effect was identified with saturation of the matrix by the analyte. The threshold of matrix saturation was found to be in the range of 1/(3000-5000) analyte/matrix molar ratio. To avoid matrix saturation the (analyte+internal standard) to matrix molar ratio should be below this threshold. Thus the internal standard concentration should be as low as possible.DHB/MSA/fucose and ferulic acid/fucose matrices demonstrated good accuracy and linearity for standard curves even when the internal standard had chemical properties different from the analyte. However, use of an internal standard with different chemical properties requires highly stable instrumental parameters as well as constant (analyte+internal standard)/matrix molar ratio for all samples.

Journal Article↗

PubMed1996

Sounds of comfort in the trauma center: how nurses talk to patients in pain.

Language that trauma center nurses directed to 29 distressed patients was systematically examined from videotaped data. A unique set of co-occurring linguistic features and intonation patterns which characterize the comfort talk register was identified. Descriptive data reveal that nurses reserve this register for patients only and that linguistic adjustments are made within the register for children. The nurses' comfort talk register is also characterized by a restricted set of pragmatic functions which include: (1) helping patients to 'hold on'; (2) obtaining information that contributes to the assessment of the patient's condition; (3) giving and receiving information about procedures; and (4) verbally communicating a sense of caring to the patient. Other grammatical and lexical features that are used in conjunction with selected intonation contours which delineate the nurse's comfort talk register are discussed relative to interactional processes.

Adult↗

PubMed1995

Application of the fast-evaporation sample preparation method for improving quantification of angiotensin II by matrix-assisted laser desorption/ionization.

The fast-evaporation method of sample preparation has been applied for quantitative analysis using matrix-assisted laser desorption/ionization (MALDI) mass spectrometry. An instrumental protocol focusing on improvement of shot-to-shot repeatability and compensation for signal degradation has been developed for quantification of angiotensin II using the fast-evaporation technique and an internal standard. The fast-evaporation method was compared to the standard method of sample preparation (using a multicomponent matrix) in the quantitative analysis of angiotensin II, and found to be superior in several respects. Improvement in sample homogeneity using the fast-evaporation method enhanced both point-to-point repeatibility and sample-to-sample reproducibility. The relative standard deviations of the analyte/internal standard ratios (point RSD) were decreased by a factor of three compared to those obtained using the multicomponent matrix method. The average point RSD was found to be ca. 5% for the fast-evaporation technique. Two internal standards were evaluated for quantification of angiotensin II. The better one, 1-SAR-8-Ile angiotensin II, yielded a relative standard deviation of the standard curve slope of ca. 2.2% over two orders of magnitude of concentration (45 nM to 3000 nM), an improvement by a factor of two over the standard preparation method. Renal microdialysate samples, spiked with angiotensin II and the internal standard 1-SAR-8-Ile angiotensin II, were also analyzed using the fast-evaporation technique. The detection limit was calculated to be in the high attomole range (675 amol). Furthermore, the accuracy for a single determination of angiotensin II concentration in these samples was found to be 13.9% with a relative error of 8.19%.

1-Sarcosine-8-Isoleucine Angiotensin II↗

PubMed1994

Quantitative measurement of cyclosporin A in blood by time-of-flight mass spectrometry.

Analytical methods have been developed for the detection and quantification of cyclosporin A (CsA) in blood using time-of-flight secondary-ion mass spectrometry (TOF-SIMS) and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI/TOF-MS). Linear calibration curves were obtained for both methods in the range 25-2000 ng/mL in whole blood. The limit of detection (LOD) and limit of quantification (LOQ) were determined to be 7 and 23 ng/mL, respectively, for the TOF-SIMS method; the LOD and LOQ were 10 and 33 ng/mL, respectively, for the MALDI/TOF-MS method. Coefficients of variation ranged from 3 to 5% for the TOF-SIMS method and from 4 to 8% for the MALDI/TOF-MS method. Blood samples were also analyzed by a nonspecific method, fluorescence polarization immunoassay (FPIA), and by a specific method, high-performance liquid chromatography (HPLC). The TOF-MS results are in good agreement with the HPLC results, but not with the FPIA results. The TOF-MS methods can also provide information about CsA metabolites.

Chromatography, High Pressure Liquid↗

PubMed1993

Amperometric sensors for peroxide, choline, and acetylcholine based on electron transfer between horseradish peroxidase and a redox polymer.

Amperometric sensors have been developed for hydrogen peroxide, choline, and acetylcholine by immobilization of horseradish peroxidase, (HRP), choline oxidase, and acetylcholinesterase in a cross-linked redox polymer deposited on glassy carbon electrodes. Peroxide sensors, prepared by immobilization of HRP alone, gave detection limits of 10 nM and a linear response up to ca. 1 mM. Coimmobilization of HRP and glucose oxidase was used to establish the feasibility of highly efficient bienzyme sensors at low substrate levels. Replacing glucose oxidase with choline oxidase produced sensors with submicromolar detection limits and a linear response up to 0.8 mM. Addition of acetylcholinesterase to the sensors generated a relatively small response to acetylcholine that demonstrates the feasibility of trienzyme sensors. At low substrate concentrations, no loss in sensitivity during a 1-day experiment was observed. The response times of these sensors are all less than 30 s with 2-s response times achieved in some cases.

Acetylcholine↗

PubMed1992

Mesenteric angioplasty for chronic intestinal ischaemia.

Mesenteric angina is a difficult diagnosis and surgical treatment carries a significant morbidity and mortality. In patients with stenotic mesenteric vascular disease angioplasty offers an alternative method of treatment. In six patients who underwent mesenteric angioplasty relief of symptoms was achieved in five. Recurrence of symptoms associated with recurrent stenosis occurred in two patients and was remedied by re-dilation in one. Mesenteric angioplasty is a safe alternative to surgical revascularisation for mesenteric stenosis causing chronic intestinal ischaemia.

Aged↗

PubMed1990

Simultaneous isolation of DNA, RNA, and antigenic protein exhibiting kinase activity from small tumor samples using guanidine isothiocyanate.

Correlative studies of genes and their expression in human tumors are often hampered by the small sample size and the need to use differing and incompatible techniques to obtain DNA, RNA, and protein. We describe an extension of the established guanidine isothiocyanate method for isolation of DNA and RNA which allows the simultaneous isolation of total cellular protein. The protein obtained by this method (from solid tumors and cell lines) was comparable to protein extracted by a standard detergent solubilization method. Antigenicity was retained as demonstrated by Western blotting for epidermal growth factor receptor and actin and by immunoprecipitation of p53. Kinase activity was similar in proteins extracted by the two methods. It seems probable that most monomeric proteins can be obtained in a form suitable for Western analysis and immunoprecipitation and that these may also retain some functional activity.

Actins↗

PubMed1989

Experimental evaluation of an endoscopic ultrasound probe: in vitro and in vivo canine studies.

We developed an endoscopic echo probe that can be passed via the biopsy channel of a flexible fiberoptic or video endoscope with a 3.5-mm channel. The probe moves along the gastrointestinal wall under direct endoscopic vision. The translational scanning action is sensed by a position potentiometer and combines with the ultrasonic B-mode echoes to produce a cross-sectional image of the wall. The system uses an ultrasound frequency of 20 MHz to produce high-resolution images. The device was used to image canine gastrointestinal tissue in vitro and in vivo during endoscopy. Ultrasound images of the gut wall correlate with histologic structure. This probe overcomes some of the problems associated with the combined ultrasound endoscopes now in use. Use of the probe with video endoscopy allows the endoscopic and ultrasound images to be displayed side by side, simplifying coordination of application of the two techniques.

Animals↗