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Biomedical subjects

G Parsons

Publications and source records attributed to G Parsons.

At least 37 records · Page 2Linked to original sources
PubMed1997

Exercise performance and magnetic resonance imaging-determined thigh muscle volume in children.

This study examined the relationships between thigh muscle volume (TMV) and aerobic and anaerobic performance in children. A total of 32 children, 16 boys and 16 girls, aged 9.9 (0.3) years completed a treadmill running test to exhaustion for the determination of peak oxygen uptake (peak VO2) and a Wingate Anaerobic Test (WAnT) for the determination of peak power (PP) and mean power (MP). The volume of the right thigh muscle was determined using magnetic resonance imaging. TMV was not significantly different in boys and girls [2.39 (0.29) l vs 2.18 (0.38) l, P > 0.05]. Peak VO2 and MP were significantly higher in boys than girls (P < 0.01) whether expressed in absolute, mass-related or allometrically scaled terms. Absolute PP was not significantly different in boys and girls but mass-related and allometrically scaled values were higher in boys (P < 0.01). TMV was correlated with absolute peak VO2, PP and MP in both sexes (r = 0.52-0.89, P < 0.01). In boys, mass-related PP was correlated with TMV (r = 0.53, P < 0.01), and in girls mass-related peak VO2 was correlated with TMV (r = -0.61, P < 0.01). However, in neither sex were allometrically scaled peak VO2, PP or MP correlated with TMV (P > 0.05). There were no significant differences between boys and girls in terms of peak VO2, PP or MP when expressed in a ratio to TMV or allometrically scaled TMV. In conclusion, this study has demonstrated that, when body size is appropriately accounted for using allometric scaling, TMV is unrelated to indices of aerobic and anaerobic power in 10-year-old children. Furthermore, there appear to be no qualitative differences in the muscle function of boys and girls in respect of aerobic and anaerobic function.

Child↗
PubMed1997

Autonomic control of bronchial circulation in awake sheep during rest and behaviour.

1. We tested the hypothesis that the pattern and the intensity of autonomic mechanisms causing vasoconstriction in the resting bronchial circulation of awake dogs also exists in awake sheep. It was also postulated that sighing behaviour and the associated bronchovascular dilatation induced by non-adrenergic, non-cholinergic (NANC) mechanisms observed in the dog exist in sheep. 2. Bronchial arterial blood flow to lower airways of both lungs of awake sheep was measured continuously using pulsed Doppler flow probes mounted on the bronchial artery at prior thoracotomy. 3. Cumulative and factorial analysis of responses to randomized combinations of autonomic alpha 1-, alpha 2-, beta 1- and beta 2-adrenoceptors and cholinoceptor autonomic blockade suggests that resting vasoconstrictor activity is less in sheep than in dogs. At normal aortic pressure, the autonomic activity of these receptor groups in the sheep lowers bronchial blood flow and conductance by 30%, whereas in the awake dog, the corresponding autonomic effect is 50%. 4. Tonic autonomic control of bronchial conductance can be partitioned in sheep to show significant and separate alpha- and beta-adrenoceptor vasoconstrictor activity at a ratio of 1.8:1, an effect normally offset by a weaker vasodilator alpha-/beta-adrenoceptor interaction. In contrast to the situation in awake dogs, cholinoceptors do not play a role in awake sheep. 5. Nitric oxide (NO) synthase inhibition in sheep using NG-nitro-L-arginine following blockade of alpha- and beta-adrenoceptors and cholinoceptors causes hypertension, but minor changes, if any, in pulmonary pressures or heart rate. Bronchial flow and conductance, however, fall from a higher resting conductance by approximately 50%, suggesting that, normally, resting bronchial flow conductance is dominated by strong tonic NO vasodilator effects that interact with weaker tonic autonomic vasoconstrictor effects. 6. Superimposed (respiratory) behaviours of sighing, sneezing and coughing, which involve negative swings in intrathoracic pressure and the movement of inspired air, evoke large active bronchovascular dilator effects. These appear to be largely NANC in origin and appear to be dependent, in part, on mechanisms associated with NO release. It is postulated that the C-fibre axon reflex using substance P, calcitonin gene-related peptide and neurokinin A may be involved. Vocalization and eructation do not evoke bronchovascular effects.

Adrenergic alpha-Antagonists↗
PubMed1996

Ten-year survey of British bats for the existence of rabies.

In 1985, a notable increase in the number of recorded cases of rabies in European bats was observed, indicating a possible spread of the rabies virus in these bats. Because of concern that the disease could be introduced into the United Kingdom by bats crossing from mainland Europe, a programme of screening dead bats for the presence of rabies and rabies-related viruses was initiated at the Rabies Research and Diagnostic Unit at the Central Veterinary Laboratory. Over a period of 10 years (January 1986 to December 1995), 1882 bats belonging to 23 species from all parts of England, Scotland and Wales have been screened for rabies antigen. All of these bats were found to be negative. Forty-one serotine bats (Eptesicus serotinus), the species of bat most commonly infected in Europe, were included in the total. Subsequent to this survey, in June 1996, a European bat lyssavirus 2 was isolated from a Daubenton's bat (Myotis daubentonii) in Newhaven, East Sussex. It is possible that this bat originated from mainland Europe but this cannot be established with certainty.

Animals↗
PubMed1995

A tandem-column chromatographic method for studying the interaction between ligands and their targets: lipopolysaccharide as a model.

The identification of a lead ligand from a library of compounds for a specific target requires both a selection process and a method to assess relative affinities. Using a tandem-column chromatographic technique, we have developed a novel and rapid method for determination of relative affinities for ligands binding to a specific target molecule. We demonstrate, using known ligands for the lipid A region of lipopolysaccharide, that the relative affinities of these ligands can be determined and may be used to characterize the competitive interaction between ligands for the same target. The method can be adapted toward screening of soluble libraries of peptides and small molecules and those ligands exhibiting a desired affinity can be rapidly selected for further characterization/development.

Amino Acid Sequence↗
PubMed1995

Day care and the incidence of otitis media in young children.

OBJECTIVE: This study assesses whether day care is a significant risk variable for otitis media in children younger than 2 years in the United States after controlling for the number of children in the day care group. DESIGN: The computerized data source used is the 1988 Child Health Supplement (N = 17,110) of the National Health Interview Survey (NHIS-CH). SETTING: The NHIS-CH data is a multistage probability sample with clustering and stratification. It represents the civilian, noninstitutionalized population of the United States. PARTICIPANTS: The NHIS-CH sample consists of one randomly selected child from each NHIS household containing a child younger than 18 years. The overall response rate for the NHIS-CH was approximately 90%. For this analysis the focus is on children younger than 2 years (N = 2294). MAIN OUTCOME MEASURES: The NHIS-CH includes a direct questioning of an adult member of the household, usually the mother, about whether the child has ever had frequent or repeated ear infections. RESULTS: After controlling for the total size of the day care group for children younger than 12 months, the previously established relationship between attending a day care center and frequent ear infections is reduced from an odds ratio of 3.17 (95% confidence interval, 1.50 to 6.71) to an odds ratio of 1.34 (not significant; p = 0.60). CONCLUSION: The total size of the day care group is an important intervening variable in the relationship between attending day care and frequent ear infections for children younger than 12 months. The size of the day care group rather than the day care per se is the primary "modifiable risk variable" for many working parents.

Child Care↗
PubMed1995

D1S80 population data in African Americans, Caucasians, southeastern Hispanics, southwestern Hispanics, and Orientals.

Allele frequencies for the locus D1S80 were determined in African American, Caucasian, Southeastern Hispanic, Southwestern Hispanic, and Oriental sample populations using the polymerase chain reaction and subsequent electrophoresis and silver staining of the amplified products. Due to the presence of anodal and cathodal electrophoretic variants (in reference to the steps in an allelic ladder), allele frequencies were established using a classification protocol based on the steps in the allelic ladder. All sample populations met Hardy-Weinberg expectations for D1S80. In addition, there was no evidence for association of alleles between the loci D1S80 and D1S7. The product of allele frequencies from the data from the sample populations in this study can be used in forensic analyses and paternity tests to estimate the frequency of a D1S80 DNA genotype.

Alleles↗
PubMed1994

A third generation immunoassay for tumor necrosis factor alpha.

Tumor necrosis factor alpha (TNF alpha) is a polypeptide cytokine produced primarily by monocytes and macrophages. It is involved in a wide variety of immune reactions. Measurement of TNF alpha originally depended upon bioassays that are of varying reliability and reproducibility. Early immunoassays for TNF alpha required handling of radioisotopes and costly disposal of radioactive waste. Subsequent use of enzymes as reporter molecules in enzyme immunoassay (EIA) has eliminated the burden of radioisotope handling and its associated costs. However, EIA has presented new challenges. Use of thimerosal as a preservative in EIAs may require high disposal costs due to its mercury content. In addition, many EIAs lack the sensitivity achievable in radioimmunoassay (RIA). We have developed a simple microplate enzyme-linked immunosorbent assay (ELISA) for the detection of TNF alpha in serum, plasma and culture supernatants. Our high affinity capture antibody has enabled us to achieve a sensitivity of 1.5 pg/mL. The assay is calibrated to the World Health Organization (W.H.O.) first international standard for TNF alpha (87/650) and exhibits excellent precision and reproducibility. Tetramethylbenzidine is used to generate the colored end product of the reaction, and thimerosal has been removed from all components.

Enzyme-Linked Immunosorbent Assay↗
PubMed1992

Characterisation of an antigenically unusual virus responsible for two outbreaks of Newcastle disease in the Republic of Ireland in 1990.

Antigenic characterisation of two highly virulent virus isolates from outbreaks of Newcastle disease on two closely connected farms in County Monaghan, Republic of Ireland, in 1990 showed the viruses to be indistinguishable but unlike other Newcastle disease viruses so far tested. However, they appeared to be antigenically closest to avirulent viruses isolated from waterfowl from several countries and from chickens in Northern Ireland in 1986. Despite the antigenic differences, chickens vaccinated with a live commercial Hitchner B1 vaccine were protected against intramuscular challenge with one of the virulent isolates.

Animals↗
PubMed1987

Immunological capture of nucleic acid hybrids and application to nonradioactive DNA probe assay.

Antibodies specific for DNA:RNA hybrids were coated onto polystyrene test tubes and applied to hybridization assays involving DNA and RNA. Synthetic DNA probes complementary to 16S rRNA of Campylobacter were labeled with biotin and hybridized to ribosomal RNA directly in lysates of bacterial cells. After hybridization, DNA:RNA hybrids were captured with immobilized anti-DNA:RNA antibody, and the biotinylated probe was detected with streptavidin-horseradish peroxidase (EC 1.11.1.7) conjugate. The assay was optimized to detect as few as 70,000 Campylobacter cells in a sample. We compared the utility of this hybridization assay with that of conventional microbiology methods by examination of 1448 stool samples from hospital clinical laboratories. The DNA hybridization assay had a sensitivity of 98.7% (75/76) and a specificity of 98.2% (1347/1372) and overall agreed with 98.2% of the conventional results for a test population that had a 5.2% incidence (76/1448) of Campylobacter infection. The assay is simple to perform and yields results within 2.5 h.

Antibodies↗
PubMed1986

Avian paramyxovirus type 1 infections of racing pigeons: 4 laboratory assessment of vaccination.

The immune response and protection from challenge afforded to adult pigeons by four different vaccination schedules were assessed. Intravenous challenge with a field pigeon isolate was done four weeks after the second of two doses of vaccine given four weeks apart. Little difference in protection was seen between two 0.25 ml and two 0.5 ml doses of oil emulsion vaccine, although the latter produced a slightly higher immune response. In both cases one of 10 challenged pigeons became sick and died. One dose of Newcastle disease virus B1 live vaccine followed four weeks later by 0.5 ml oil emulsion vaccine gave a comparable immune response to two 0.25 ml doses of oil emulsion but only six birds survived challenge. Two doses of Newcastle disease virus B1 vaccine gave a poor immune response and little protection from challenge; all 10 birds became sick and eight died. Assessment of the onset of protection following one dose of either 0.5 ml oil emulsion vaccine or Newcastle disease virus B1 indicated some partial protection in the latter group as early as five days after vaccination. Both groups showed protection at 10 days but by 21 days, although protection was sustained in the oil emulsion group, birds receiving live vaccine were fully susceptible. Measurement of the duration of protection in pigeons given two 0.5 ml doses of oil emulsion vaccine indicated that protection had begun to wane by 40 weeks after the first dose.

Animals↗
PubMed1985

Newcastle disease outbreaks in fowl in Great Britain during 1984.

During February to July 1984, 23 outbreaks of Newcastle disease were confirmed in chickens in Great Britain. Use of available mouse monoclonal antibodies enabled unequivocal identification of the virus responsible for 22 of the outbreaks as similar to the avian paramyxovirus type 1 (A/PMV-1) virus causing neurotropic disease in pigeons during 1983 and 1984. Epidemiological investigations presented evidence that 19 of these outbreaks occurred either directly or indirectly as a result of spread from diseased pigeons infesting food stores at Liverpool docks. Virus was isolated from carcases of pigeons found among the food and samples of the food itself. The remaining outbreak was shown to involve a virus unrelated to the virus infecting pigeons.

Animals↗
PubMed1985

The aging respiratory system.

In this review article, the effects of old age on lung structure and function are discussed. Changes in lung morphology and biochemistry are correlated with changes in lung mechanics and gas exchange, as well as with the respiratory system's adaptability to the stresses of exercise and sleep. The effects of aging on the lungs' defense mechanisms are related to pulmonary diseases of the elderly.

Adaptation, Physiological↗