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Biomedical subjects

G W Morgan

Publications and source records attributed to G W Morgan.

At least 37 records · Page 2Linked to original sources
PubMed1992

Quantitative pulmonary gallium scanning in interstitial lung disease.

The mechanisms responsible for gallium uptake in chronic, non-infective, diffuse lung disease are not completely understood. This study attempted to clarify some of them. A lung/liver gallium index was calculated in 113 subjects, some normal and some with various interstitial lung diseases, predominantly those associated with connective tissue disease. The mean gallium index was significantly higher in the groups with active interstitial lung disease (5.7) and non-infective bronchiolitis (4.1) compared with non-smoking normals (3.0; P less than 0.05). To investigate the mechanisms responsible for gallium uptake, the gallium index was correlated with bronchoalveolar lavage findings, respiratory function tests and clinical features. Significant correlations (P less than 0.05) were found with age in non-smoking normals; lavage macrophages in smoking normals; age but no other parameter in bronchiolitis; lavage lymphocytes, lavage albumin and improvement in diffusion capacity for carbon monoxide in those with active interstitial lung disease. It is concluded that in normal smokers gallium uptake may be due to a macrophage-mediated process. Gallium uptake in active interstitial lung disease associated with connective tissue disease appears to be an immunological process in which transport and retention of gallium is associated with that of albumin.

Bronchiolitis↗
PubMed1992

Smoking-induced changes in epithelial lining fluid volume, cell density and protein.

Bronchoalveolar lavage has proved a useful research technique for recovering cellular and molecular contents of the lower respiratory tract. Because the recovered fluid is variably diluted, an accurate estimation of molecular and cellular concentrations can only be made if the epithelial lining fluid volume recovered is also known. It has been suggested that smoking may alter epithelial lining fluid volume by reducing clearance or by stimulating production and, thus, affect the interpretation of bronchoalveolar lavage studies. In this study, urea was used as an endogenous marker of epithelial lining fluid volume in a comparison of 26 smokers and 31 nonsmokers. The mean epithelial lining fluid volume recovered from smokers was significantly greater than that of nonsmokers (2.4 +/- 1.40 ml vs 1.2 +/- 0.75 ml, p less than 0.005). The total cellular concentration in the bronchoalveolar lavage fluid in smokers was also greater (94.2 +/- 46 x 10(6) vs 33.9 +/- 21.5 x 10(6) cells per 300 ml lavage), even when corrected for bronchoalveolar lavage volume recovered (63.1 +/- 32.5 x 10(6) vs 24.9 +/- 13.3 x 10(6) cells per 100 ml recovered lavage fluid). This was true for macrophage, lymphocyte and neutrophil cell numbers. However, when corrected for the apparent epithelial lining fluid volume, only the macrophage count remained significantly higher in the smokers compared with nonsmokers (30.66 +/- 20.7 x 10(6) vs 18.21 +/- 8.6 x 10(6) macrophages.ml-1 ELF). In addition, concentrations of albumin and immunoglobulin M (IgM) were significantly lower in smokers after correction for epithelial lining fluid volume. These results highlight smoking as a confounding factor in the interpretation of bronchoalveolar lavage data.(ABSTRACT TRUNCATED AT 250 WORDS)

Bronchoalveolar Lavage Fluid↗
PubMed1991

Interstitial lung disease associated with connective tissue diseases. The use of statistical structure analysis in model development.

Interstitial lung disorders associated with the connective tissue diseases are thought to be quite common, but their precise analysis is fraught with difficulty because of the absence of a Gold Standard that, short of open lung biopsy, is not available. Analysis is hampered by the biologic variability in test results, large overlap between the normal and the disease population for individual tests, the confounding effect of smoking, and the complexities of viewing multidimensional data. In order to better define the pattern of the lung involvement, an entirely different approach has been adopted that is based on the use of graphic and clustering techniques to define the multivariate structure inherent in the data, then discriminant analysis to assign patients into distinct clusters. Using this approach it has been possible to group patients into four distinct clusters based on the result of respiratory function studies, gallium lung scan, bronchoalveolar lavage, and smoking status. These clusters are a normal smoking cluster and a normal nonsmoking cluster, a cluster of patients with active ILD, and a cluster with bronchiolitis. The validity of this method has been verified, and an algorithm has been developed that allows the assignment of any new patient entering the study into one of these clusters. This type of analysis offers a valuable new approach to the categorization of patients into distinct groups based on the results of multiple investigations.

Algorithms↗
PubMed1989

Effect on EEG responses of removing ocular artefacts by proportional EOG subtraction.

Work undertaken to investigate the effect on EEG responses of ocular artefact removal by proportional electro-oculogram subtraction using the least-squares method is reported. The ocular artefact model and the least-squares approach to estimation of the model parameters and hence of the EEG waveform, including the response, are described. Results are presented to show that the response shapes become modified if ocular artefact removal is implemented recursively. This happens because the response is incorrectly treated as part of the random background EEG. The solution is to incorporate a model of the response within the ocular artefact removal algorithm. The results of tests on simulated data confirm these conclusions. The results of the incorporation of response models in removing ocular artefacts from CNV recordings are presented. Even with modelling recursive ocular artefact removal is found to modify the shape of the CNV, and so reliable results can only be obtained if the removal is implemented nonrecursively. Evidence is given that it is advisable to remove DC levels from the recorded data.

Electroencephalography↗
PubMed1989

Spectral analysis of EEG responses.

The techniques used and the results obtained in a spectral analysis of two specific responses in the human electroencephalogram are presented in this paper. The purposes are to show how the techniques may be applied to the necessarily short lengths of EEG data and to illustrate these techniques and the useful results obtained by relevant examples. The necessary data-processing procedures and precautions for transforming from the time to frequency domain are presented in a tutorial fashion. The importance of augmenting zeros, choice of the most appropriate data window and pretransformation of the data to avoid the combined effects of energy loss and low frequency content biasing caused by windowing is explained. The pros and cons of the tapered-cosine (Tukey) and Kaiser-Bessel windows are illustrated. The usefulness of applying certain statistical tests, which are based on a physical model of the responses, to the harmonic components of the responses is demonstrated. Thus a comparison is made between the features of auditory evoked responses and of the contingent negative variation, and the usefulness of predictive statistical diagnosis in differentiating between subject groups is illustrated by application to normal subjects and Huntington's chorea patients.

Biomedical Engineering↗
PubMed1989

Effect of refeeding following short-term deprivation of feed or water, or both, on selected physiological parameters for broiler chickens.

Two experiments were conducted to determine the effects of refeeding broilers following a 12-h fast on body weight, serum glucose, serum protein, packed cell volume, hemoglobin, serum sodium, serum potassium, and plasma refractive index. Four fasting regimens were utilized in each experiment: 1) full feed and water (control); 2) no feed with full water; 3) full feed with no no water; and 4) no feed and no water (NFNW). Following the 12-h fast, all birds were returned to feed and water with ad libitum access. Birds deprived of feed or water, or both, for 12 h gained more weight attributable to feed and water consumption than did the control birds during the 12-h refeeding period. Following refeeding, serum glucose values for the birds receiving only water during the fast were higher initially than those for the control birds; glucose values for the NFNW birds returned to normal. Hemoglobin values for birds receiving no feed during the fast initially were higher than for the control group after refeeding. The other blood parameters measured remained virtually unchanged during the 12 h monitored after refeeding.

Animal Feed↗
PubMed1988

Radiation-induced lung injury: a hypersensitivity pneumonitis?

Radiation pneumonitis occurs 6 to 12 weeks after thoracic irradiation, and is thought to be due to direct radiation-induced lung injury. Four patients who developed pneumonitis after unilateral thoracic irradiation for carcinoma of the breast were studied with bronchoalveolar lavage, gallium scan of the lung, and respiratory function tests. On the irradiated side of the chest, all four patients showed an increase in total cells recovered from the lavage fluid and a marked increase in the percentage of lymphocytes. When results for the unirradiated lung were compared with results for the irradiated lung, there was a comparable increase in total cells and percentage of lymphocytes. Gallium scans showed increases for both irradiated and unirradiated lungs. Prompt improvement was seen after corticosteroid therapy in all patients. The fact that abnormal findings occur equally in irradiated and unirradiated lung is inconsistent with simple direct radiation-induced injury and suggests an immunologically mediated mechanism such as a hypersensitivity pneumonitis.

Aged↗
PubMed1988

Resource allocation in multifacility emergency medical service systems.

As instruments of public policy, Emergency Medical Service Systems must not only make effective use of the available resources but also ensure that those resources are shared equitably by the systems' facilities. This paper develops a multifacility EMS system resource allocation model that enables its user to evaluate the equitability of resource allocation schemes. Recognizing and objectively defining the relationships between the consumption of system resources and the provision of EMS System services, this model is appropriate for use in both prospective and retrospective EMS System resource allocation analyses.

Cost Allocation↗
PubMed1988

Cyclic watering of broiler cockerels.

Two trials were designed to compare the performance of broilers receiving free access to water with those receiving cyclic access to water. Birds that received water in cyclic pattern were presented water by the activation of waterers for 15 min in each 3-h cycle (Trial 1) or 30 min in each 4-h cycle (Trial 2). In each trial, the control group received water ad libitum. Feed and water consumption and body weight were reduced in the cyclic-watered birds after 21 days of age in Trial 1 and were not different in the cyclic-watered birds in Trial 2 when compared with values for controls. Water:feed ratio and feed conversion values of the cyclic-watered birds were not altered by the cyclic watering regimens used in Trials 1 and 2. Observations of drinking patterns in Trial 2 demonstrate that the cyclic presentation of water can induce meal-drinking in cyclic-watered birds, but the feeding pattern of these birds was not altered. These data demonstrate that alteration of drinking activity can be accomplished without affecting growth and feed efficiency, and that altered drinking activity does not necessarily alter feeding activity.

Animals↗
PubMed1988

Position of Meckel's diverticulum in broiler-type chickens.

In each of three trials broiler-type chickens were used to determine whether Meckel's diverticulum resides in a constant position along the intestinal tract. Chickens were provided a basal diet ad libitum through 49 (Trials 2 and 3) or 52 days of age (Trial 1). Body weight and total intestine length as well as the lengths of the intestine from the gizzard to Meckel's diverticulum (GMD) and from Meckel's diverticulum (MD) to the cecal openings (MDC) were then recorded. When intestine length was expressed as a percentage of body weight, significant differences were noted between sexes. However, no significant differences were observed between sexes for either GMD or MDC relative to total intestinal length. Results of this study indicate that MD resides in a constant position along the length of the intestinal tract. This constancy of position supports the use of MD as a boundary point of the intestine.

Animals↗
PubMed1985

Late cardiac, thyroid, and pulmonary sequelae of mantle radiotherapy for Hodgkin's disease.

Cardiac, thyroid and pulmonary function were evaluated in 25 patients aged 35 years or under, treated for Hodgkin's disease by mantle radiotherapy 5-16 years previously. No patient had symptoms of heart disease. Although thallium myocardial perfusion scintigraphy was normal in all patients, abnormalities of myocardial function were detected in 6 (24%) patients using gated equilibrium rest and exercise radionuclide ventriculography. Resting left ventricular ejection fraction (LVEF) was abnormal in 1 patient, and in 3 patients there was an abnormal LVEF response to exercise. All 6 patients had right ventricular dilatation. Apical hypokinesia was present in 4 of these patients. A small asymptomatic pericardial effusion was detected by M-Mode echocardiography in only 2 (8%) patients. Twenty-three (92%) patients had evidence of abnormal thyroid function. Two (8%) patients had become clinically hypothyroid. Serum TSH was elevated in 13 (52%) patients and TRH stimulation test was abnormal in a further 10 (40%) patients in whom TSH was normal. Pulmonary function studies showed a moderate decrease in diffusing capacity (72% of predicted) and a minor reduction in lung volume. Although a high incidence of cardiac, thyroid and pulmonary abnormalities was detected, only the 2 patients who had become hypothyroid were symptomatic. Modification of the irradiation technique may reduce the incidence of cardiac abnormalities, but is unlikely to alter significantly the thyroid or pulmonary sequelae.

Adult↗
PubMed1984

Physiological profile of caged layers during one production year, molt, and postmolt: egg production, egg shell quality, liver, femur, and blood parameters.

A longitudinal study of a flock of Single Comb White Leghorn pullets was initiated at 19 weeks of age (preproduction) and continued through a production year, a forced molt, and for 4 months of postmolt production. A representative sample of hens was obtained at 12-week intervals during the first year and at subsequent selected times. Liver lipid, femur weight, femur volume, femur density, egg weight, shell weight, percent shell, milligrams shell/square centimeter of shell surface area, serum calcium, serum phosphorus, and serum alkaline phosphatase were determined. Percent hen-day production peaked at 90% and then declined by .6 to .7% each week during the first production year. After molting, percent hen-day egg production peaked at 80% and declined .9% per week over the subsequent 20 weeks. Egg weight increased continually during the first production year. Shell weight was greatest immediately postmolt; thereafter it declined. Shell thickness was greatest at 31 weeks of age and declined throughout the first year. After molting, the shell thickness of 83-week-old hens was similar to values of hens about 37 weeks of age. Serum calcium and phosphorus of laying hens were influenced by age, feed intake and environmental temperature. The lowest values occurred during hot weather. Liver lipid was lowest in nonlaying hens (17 to 20%) and was approximately 42% of dry weight in laying hens. Femur density was greater in laying than nonlaying hens.

Alkaline Phosphatase↗
PubMed1983

Ontogeny of delayed hypersensitivity in young turkeys.

Hypersensitivity to phytohemagglutinin (PHA-P) and Freund's adjuvant containing Mycobacterium tuberculosis was investigated in turkey poults. The kinetics, as indicated by dosage and response time after sensitization, were similar to responses in other birds and laboratory mammals. Newly hatched poults demonstrated delayed hypersensitivity responses, and 2 week old poults exhibited responses of greater magnitude than 8 week old poults. The turkey is proposed as another acceptable species for study of cell-mediated immunity (CMI).

Age Factors↗
PubMed1983

Grouping in Japanese quail 2. Suppression of humoral immunity.

Four-week-old Japanese quail were placed in either stable (isolate) or unstable (resident-visitor) groupings in this study. The visitor quail were transferred daily to cages containing unfamiliar residents, and the isolate quail were handled daily. The immune responsiveness to sheep red blood cells (SRBC), as indicated by production of hemagglutinins of the visitors and residents, was significantly less than that of the isolates, and the visitors were found to have less antibody than the residents. In subsequent experiments adrenocorticotropic hormone (ACTH) was used to compare its effect on immune responsiveness to that caused by grouping. The ACTH caused a suppression in humoral immune response, but only 8 IU ACTH/100 g body weight consistently suppressed antibody levels, indicating that the quail immune system is moderately resistant to this hormone. At the end of the experimental periods the bursa of Fabricius, spleen, and adrenal glands were removed. The relative weights of the organs suggested that grouping and ACTH did not induce the classical symptoms of physiological stress. However, stress was not eliminated as a possible cause of the immunosuppressive effects of grouping and ACTH found in this study, because there was significant body weight loss in unstable groupings and in ACTH-treated birds.

Adrenal Glands↗
PubMed1982

Physiological changes in caged layers during a forced molt. 4. Leucocytes and packed cell volume.

Packed cell volume and circulating leucocyte numbers in force-molted, Single Comb White Leghorn (SCWL) hens were examined. Two groups of SCWL hens, reared under commercial conditions, were subjected to force molting (FM) at 70 (Trial 2) and 72 weeks of age (Trial 1). The force molting procedure consisted of a reduced photoperiod (6 hr), feed removal for 12 days (Trials 1 and 2), and water withdrawal for 1 day (Trial 1 only). Cessation of egg production was achieved in 6 days. Control (CON) hens were maintained in each trial with no change in daylength, and feed and water were available ad libitum. The FM hens exhibited a significant increase in packed cell volume (PCV) from the time of feed removal until immediately prior to resumption of egg production. This effect was not associated with water deprivation. The FM hens exhibited numerically increased numbers of total leucocytes (TWBC) and monocytes throughout the nonlaying period. However, the increase was significant on Day 14 of both trials for TWBC and on Days 21 and 35 (Trial 1) and Days 14 and 48 (Trial 2) for monocytes. A significant eosinophilia was observed on Days 7 and 14 of both trials. Changes associated with lymphocytes, heterophils, and basophils were inconsistent. Lymphocytes were increased significantly in the FM hens of Trial 2 from Day 21 to Day 48, but no significant difference occurred in Trial 1. A heterophilia was exhibited by the FM hens of Trial 1 on Days 7 and 14, but not in Trial 2. Conversely, a significant basophilia was observed on Days 7 and 14 in Trial 2, but not in Trial 1. These data suggested that an increased PCV, eosinophilia, and possibly increased TWBC and monocyte numbers were associated with a forced molt in caged SCWL hens.

Animals↗