Search PubMed⌕ Search

Biomedical subjects

R S Chapman

Publications and source records attributed to R S Chapman.

At least 73 records · Page 4Linked to original sources
PubMed1987

Evaluation and clinical application of a two-site immunoradiometric assay for alpha-1-foetoprotein using readily available reagents.

The development and evaluation in routine clinical practice of a simple, rapid, high-throughput, immunoradiometric assay (IRMA) for alpha-foetoprotein (AFP) in serum and amniotic fluid is described. The assay uses readily available reagents; a radioiodinated mouse monoclonal antibody produced by the authors and the immunoglobulin G (IgG) fraction of a polyclonal sheep anti-human-AFP serum covalently linked to Sepharose CL-4B. Both antibodies are distributed by the Scottish Antibody Production Unit (Law Hospital, Carluke). The results of an extensive comparative trial between the IRMA and a radioimmunoassay (RIA) are presented. A high-dose 'hook' effect is not a problem in this system. Quantitative recovery was obtained, independent of the assay diluent. The IRMA has high sensitivity and a wide working range. Improved assay precision allowed a clinically significant change in the intervention limits.

Amniotic Fluid↗
PubMed1986

Application of solid-phase antibodies to radioimmunoassay. Evaluation of two polymeric microparticles, Dynospheres and nylon, activated by carbonyldiimidazole or tresyl chloride.

Two types of polymeric microparticle, Dynospheres and reprecipitated acid-hydrolysed nylon 6/6, and two methods of activating these particles with either tresyl chloride or carbonyldiimidazole (CDI) prior to covalent linkage of antibodies were investigated with a view towards their respective adoption for the preparation of general solid-phase reagents for immunoassay applications. Activation of each particle and coupling of antibodies was rapid irrespective of the activator. CDI proved to be the activator of choice since it was cheap, less hazardous, more efficient and less pH dependent than tresyl chloride. Both types of microparticle remain buoyant during the RIA incubation periods and form stable pellets after centrifugation. In second antibody applications immobilisation of the first antibody occurs with a short incubation period of 30 min. Nylon microparticles have a higher antibody-coupling capacity and are the particles of choice in both first and second antibody applications. However, the nylon microparticles possess marginally higher non-specific binding characteristics.

Animals↗
PubMed1986

Development and evaluation of a simple, direct, solid-phase radioimmunoassay of serum cortisol from readily available reagents.

A simple, rapid solid-phase radioimmunoassay for serum cortisol was developed using cortisol antibody distributed by the Scottish Antibody Production Unit and commercially available radioiodinated cortisol ligand. The assay involves a 1-h incubation at ambient temperature, using the antibody covalently linked by the easily performed carbonyldiimidazole method, to microcrystalline cellulose. A detailed comparison of the accepted 0.125 mol/l citrate, pH 4.0, and an alternative 0.1 mol/l phosphate/8-anilinonaphthalene sulphonic acid, pH 7.4, diluent demonstrated similar precision (within-assay 10% to 5%; between-assay 11% to 6% over the range 100-1000 nmol/l cortisol) and recovery (median recoveries: phosphate 98.6%, citrate 99.5%). Linear regression analysis of human serum cortisol concentrations in comparison with the 'Amerlex' cortisol RIA kit gave the following results: citrate = 1.029. 'Amerlex' - 3.5 nmol/l (n = 80, r = 0.967); phosphate = 1.017, 'Amerlex' + 26.2 nmol/l (n = 80, r = 0.961). Phosphate, pH 7.4 diluent was adopted as the diluent of choice, since it was economical of antibody and maintained good precision over a wider working range of cortisol concentration.

Adult↗
PubMed1986

Mother's speech to their 1-year-old infants in home and laboratory settings.

The speech of mothers and their 1-year-old infants was compared in the home and in the laboratory playroom. The home and laboratory settings were similar for measuring the number of actual words that infants spoke and were similar for measuring the complexity of the mother's speech, including the number of different words, the type-token ratio, and the length of the utterances. Infants vocalized at similar rates in the two settings, but mothers spoke at a faster rate in the laboratory playroom. The usefulness of a preliminary warm-up period was supported by the finding that, for the second half of the sessions, mothers slowed their rate of speech and increased the complexity of their speech.

Female↗
PubMed1985

Prevalence of persistent cough and phlegm in young adults in relation to long-term ambient sulfur oxide exposure.

In early 1976, a survey of persistent cough and phlegm (PCP) prevalence was conducted in 5,623 young adults in 4 Utah communities. Over the previous 5 years, community-specific mean sulfur dioxide levels had been 11, 18, 36, and 115 micrograms/m3. Corresponding mean suspended sulfate levels had been 5, 7, 8, and 14 micrograms/m3. No intercommunity exposure gradient of total suspended particulates or suspended nitrates was observed. In nonsmoking mothers, PCP prevalence was 4.2% in the high-exposure community and approximately 2.0% in all other communities. In smoking mothers, PCP prevalence was 21.8% in the high-exposure community and approximately 15.0% elsewhere. In nonsmoking fathers, PCP prevalence was 8.0% in the high-exposure community and averaged 3.0% elsewhere. In smoking fathers, PCP prevalence was less strongly associated with ambient sulfur oxide exposure. Intercommunity prevalence differences in smoking and nonsmoking mothers, and in nonsmoking fathers, were significant at alpha = 0.05. A categorical logistic regression model, testing simultaneously for effects of community and several covariates on PCP prevalence, yielded similar results. The results of this survey were similar to those of a similar survey conducted in Utah in 1970 and to those of other surveys. These results disclose an association of PCP prevalence with ambient sulfur oxide exposure, stronger in mothers than in fathers, stronger in nonsmokers and ex-smokers than in smokers, and stronger in 1970 than 1976.

Adult↗
PubMed1985

Respiratory responses of vigorously exercising children to 0.12 ppm ozone exposure.

Changes in respiratory function have been suggested for children exposed to less than 0.12 ppm ozone (O3) while engaged in normal activities. Because the results of these studies have been confounded by other variables, such as temperature or the presence of other pollutants or have been questioned as to the adequacy of exposure measurements, we determined the acute response of children exposed to 0.12 ppm O3 in a controlled chamber environment. Twenty-three white males 8 to 11 yr of age were exposed once to clean air and once to 0.12 ppm O3 in random order. Exposures were for 2.5 h and included 2 h of intermittent heavy exercise. Measures of forced expiratory volume in one second (FEV1) and the symptom cough were determined prior to and after each exposure. A significant decline in FEV1 was found after the O3 exposure compared to the air exposure, and it appeared to persist for 16 to 20 h. No significant increase in cough was found due to O3 exposure. Forced vital capacity, specific airways resistance, respiratory frequency, tidal volume, and other symptoms were measured in a secondary exploratory analysis of this study.

Child↗
PubMed1985

Evaluation of a time-resolved immunofluorometric assay for serum thyroid stimulating hormone.

The LKB 'Delfia, immunofluorometric assay for serum TSH has been evaluated. The assay is simple and rapid to perform and is capable of processing in excess of 100 specimens within a working day. The sensitivity of the assay is 0.05 microU/L, with a working range extending beyond 324 microU/L. The change in signal at each point over the standard curve approaches 1000-fold, significantly greater than that of a typical immunoradiometric assay. Mean figures for intra-assay and inter-assay precision were 4.7% and 8.6% CV, respectively. Mean recovery of added TSH was 98.3%, and samples containing high levels of endogenous TSH diluted parallel to the standard curve. The method showed good correlation with an immunoradiometric assay for TSH. The reference ranges for clinically defined groups of subjects were euthyroid 0.47-3.84 microU/L (n = 83); primary hypothyroidism 15--greater than 324 microU/L (n = 28); thyrotoxicosis less than 0.05 microU/L (n = 46). It is concluded that the 'Delfia' assay offers the clinical biochemistry laboratory an attractive and reliable alternative to a sensitive immunoradiometric assay for serum TSH.

Evaluation Studies as Topic↗
PubMed1984

Disorders of communication: investigating the development of language of mentally retarded children.

Research conducted at the Waisman Center on Mental Retardation and Human Development over the past 10 years documents the multidimensional nature of the development of children's language in retarded and nonretarded populations. Recent advances in research methodology now available for investigating language comprehension and production will allow large-scale indepth studies of the lexical, semantic, syntactic, and pragmatic aspects of the language performance of a variety of retarded populations.

Child↗
PubMed1982

Immunoassay of blood spot TSH; development of a rapid two-site immunoradiometric assay and comparison with radioimmunoassay as a screening method for neonatal hypothyroidism.

The development of a two-site immunoradiometric assay (IRMA) for thyrotropin (TSH) eluted from dried blood filter paper discs is described and compared with a conventional TSH radioimmunoassay (RIA) as a screening procedure for neonatal hypothyroidism. The iodinated antibody for the IRMA is prepared by a reproducible four step procedure. Specific antibody is selected from whole TSH antiserum with TSH covalently linked to microparticulate cellulose, iodinated as the solid phase antigen-antibody complex, and eluted by repeated changes in pH from 3 to 10. The pooled eluted material is finally purified by Sepharose 6-B gel chromatography to recover labelled monomeric anti-TSH IgG. Solid phase antibody for the IRMA is prepared by covalently linking a partially purified IgG fraction of TSH antiserum to carbonyldiimidazole-activated microparticulate cellulose. Typically yields of 2-3 mg protein per 100 mg cellulose (2-3%, w/w) are obtained. The two-site IRMA involves a primary incubation of excess labelled TSH antibody and the blood disc for 16-18 h at pH 8 and a secondary 3 h incubation under agitation, with solid phase TSH antibody. Bound and free fractions are separated by a semi-automated washing procedure. Compared with the conventional RIA, the two-site IRMA is quicker (results available within 24 h compared to 3 days for RIA), more precise at clinically important TSH levels (25-30 mU TSH/l), and more sensitive (detection limit less than w mU/l compared to 6 mU/l for RIA). The two-site IRMA is technically simpler than RIA and has proved rugged in routine practice. TSH levels in filter paper blood spots prepared from whole blood with levels of standard TSH (MRC 68/38) within the range 6 to 200 mU/l, correlated well in both assays (r = 0.969). Recoveries of 98% and 104% were demonstrated for the two-site IRMA and RIA, respectively. It is concluded that the two-site TSH IRMA has advantages over conventional RIA in speed, sensitivity, precision and ruggedness and can be recommended as an efficient screening procedure for neonatal hypothyroidism.

Autoanalysis↗
PubMed1981

The relation between age and mean length of utterance in morphemes.

The relationship between child age and mean length of utterance measured in morphemes (MLU) was studied in a sample of 123 middle- to upper-middle-class midwestern children, aged 17 to 59 months, conversing with mothers in free play. A significant correlation was found between age and MLU: r = .88. Age accounted for 78% of the variance when MLU was regressed on age; and MLU accounted for 77% of the variance when age was regressed on MLU. Significant nonlinear components accounted only for an additional 1% and 3% (respectively) of the variance. Ranges within one standard deviation (SD) were estimated for predicted MLUs and derived for predicted ages on the basis of linear regression. MLU increased at an average rate of 1.2 morphemes per year; predicted variability in predicted MLU increased with age. These findings can play a useful role in three activities when the children studied are from populations similar to the one sampled here, and MLUs are obtained in the same way. They can aid in (1) finding children whose development of productive syntax requires further diagnostic evaluation; (2) finding children at a particular linguistic stage quickly; and (3) predicting the age most likely to be associated with a given MLU. The substitution of local MLU norms, sampled from the population and ages of clinical interest, can further sharpen these evaluations.

Age Factors↗
PubMed1981

The epidemiology of tracheobronchitis in pediatric practice.

Epidemiologic characteristics of childhood tracheobronchitis occurring over a 104-month period in Chapel Hill, NC, were ascertained and compared to those of other pediatric lower respiratory illness (LRI) syndromes. Tracheobronchitis accounted for 40% of all LRI seen at the community's only pediatric practice. Tracheobronchitis incidence was highest during the first two years of life, through the ratio of tracheobronchitis incidence to total LRI incidence increased with age. A viral pathogen or Mycoplasma pneumoniae was isolated from 23% of tracheobronchitis cases; the agents most commonly isolated were parainfluenza viruses, influenza viruses, respiratory syncytial virus, and M. pneumoniae. Influenza virus, particularly type B, was isolated more commonly in tracheobronchitis than in other LRI syndromes. Over all age groups, peak incidence of tracheobronchitis, like that of pneumonia and bronchiolitis, occurred during the winter months. In school-age children, however, tracheobronchitis incidence was more likely than that of other syndromes to be elevated in late winter or early spring, when several influenza B outbreaks occurred in Chapel Hill. Available evidence suggests that risk of chronic respiratory disease is related inversely to age at which acute respiratory infection first occurs, and that a component of wheezing may not be required to confer such risk. These considerations, coupled with the high incidence of tracheobronchitis early in life, warrant further description of this syndrome and assessment of its implications.

Age Factors↗