Biomedical subjects
D W Morgan
Publications and source records attributed to D W Morgan.
The adaptation to prison by individuals with schizophrenia.
This report documents the adjustment to prison life by individuals with schizophrenia and compares their adaptation with a control group with no known mental illness matched for age, race, sex, most serious crime, and security level. On all outcome variables, number of infractions, number of "lock-ups", days in "lock-up," ability to obtain a job in prison, and ability to obtain release from prison, the group with schizophrenia was inferior to the control group. That inmates with schizophrenia may require special assistance in prison and the need for future investigation are discussed.
Interrelationships between mechanical power, energy transfers, and walking and running economy.
The interrelationships between aerobic demand, kinematic and kinetic-based estimates of mechanical power output and energy transfer, and total body angular impulse (summation of net joint moments integrated with respect to time over a stride) were quantified for walking at 1.69 m.s-1 and running at 3.35 m.s-1 to assess the ability of these various biomechanical expressions to explain interin-dividual differences in walking and running economy. Fourteen healthy men participated in the walking study and 16 recreational male runners were subjects for the running analysis. Each subject performed treadmill locomotion for determination of aerobic demand and overground locomotion from which biomechanical measures were quantified. It was expected that mechanical power and angular impulse expressions would correlate positively with aerobic demand while energy transfer expressions would correlate negatively. Correlations between aerobic demand and power estimates primarily were positive, but explained no more than 32% of the variability in walking or running VO2 (center of mass model: 0.22 < r < 0.57; segment-based model: -0.02 < r < 0.20; kinetic model: -0.07 < r < 0.22). Total body angular impulse also correlated positively with aerobic demand (0.32 < r < 0.42). Energy transfer expressions from the various analytical models showed no consistent relationship with aerobic demand, either in terms of magnitude or direction (-0.26 < r < 0.48). It was concluded that mechanical power, energy transfer, and angular impulse expressions frequently used in analyses of gait explain only a small proportion of normal interindividual variability in the aerobic demand at a given speed of walking or running.
Interleukin-1 beta stimulates cytosolic phospholipase A2 in rheumatoid synovial fibroblasts.
Phospholipase A2 (PLA2) activities in rheumatoid synovial fibroblasts (RSF) stimulated with interleukin-1 beta (IL-1 beta) were investigated. RSF incubated in the presence of IL-1 beta (120 pg/ml) for 18 h secreted 35 fold more PGE2 than did those incubated without IL-1 beta. IL-1 beta treatment did not increase the level of secretory PLA2 (sPLA2) activity or sPLA2 protein in the conditioned medium or subcellular fractions of lysed RSF. In contrast, the cell-associated PLA2 activity increased 3 to 4 fold in IL-1 beta stimulated RSF when compared with the control. The IL-1 beta stimulated, cell-associated PLA2 required submicromolar concentrations of calcium for activity, a characteristic consistent with the calcium sensitivity of cytosolic PLA2 (cPLA2) activity reported in other cell types, such as U937 cells. These findings demonstrate that an elevation in a cytosolic PLA2, rather than a sPLA2, is associated with increased PGE2 production in IL-1 beta stimulated RSF.
Use of a portable manometer as a screening procedure in voice rehabilitation.
Abnormal tone in the pharyngo-oesophageal (PO) segment may lead to failure in developing oesophageal speech. Videofluoroscopy may give a qualitative assessment of the PO segment but is expensive, time consuming and lacks quantification. A custom built PO segment manometer was therefore assessed as a means of predicting eventual oesophageal speech outcome. Two groups of patients were studied. In group 1 (18 patients) the PO segment pressures were compared to their videofluoroscopy findings. Videofluoroscopy categorized the patients into four groups. The PO pressures corresponded to this grouping, pressures above 20 mmHg being associated with voice failure. In group 2 (12 patients) the PO pressures in the early post-operative period were compared to their eventual speech outcome. In all cases the pressures predicted the eventual speech outcome. The pressure manometer is a simple, cheap and portable device which is a reliable screening test to predict the potential for oesophageal speech.
Extrapulmonary sites of Pseudomonas aeruginosa in adults with cystic fibrosis.
BACKGROUND: Pseudomonas aeruginosa infection is seldom eradicated in patients with cystic fibrosis despite intensive antipseudomonal treatment. Upper airway sites of infection may contribute to perpetuation of lower airways infection. This study was designed to find out which extrapulmonary sites are infected and whether the strains at these sites are identical to those in the lungs. METHODS: Sputum and upper airway samples from 42 patients were cultured for P aeruginosa and stool samples from 20 patients were also tested. Nineteen isolates from sputum and extrapulmonary sites from four patients were genotyped with the pCM tox probe. RESULTS: P aeruginosa was isolated from the sputum of 36 patients, 34 of whom had infection in the upper airways. Six of the 20 patients tested were positive for P aeruginosa in the stool. The nasopharynx was colonised in 30 patients, the oropharynx in 29, the middle meatus in 13, the external nares in six, and the inferior turbinate in four. Three of four patients tested had the same strain of P aeruginosa (a different one in each individual) in the sputum and the upper airways, and in two of the three the stool isolate was a different strain. CONCLUSION: Most adults with cystic fibrosis and P aeruginosa pulmonary infection have upper airway reservoirs of the organism and strains from these sites are identical to those in the lungs.
Introduction: economy of running: a multidisciplinary perspective.
This symposium endeavors to address the issue of running economy from a multidisciplinary perspective. Topics addressed in this symposium include physiological aspects of running economy, changes in running economy with age during childhood and adolescence, biomechanical considerations for economical walking and running, psychological state and running economy, and running economy of elite performers. While the knowledge base in this area is expanding, future research should emphasize the formulation of testable hypotheses and the fostering of collaborative efforts aimed at identifying and manipulating variables associated with improved economy and discovering mechanisms underlying economical running styles.
Physiological aspects of running economy.
The study of running economy has important performance implications for the long-distance runner and may provide insight into mechanisms underlying economical human locomotion. Physiological aspects of running economy discussed in this paper include intraindividual variability, body temperature, heart rate, ventilation, muscle fiber type, gender, air and wind resistance, altitude, fatigue, and training. The lack of consensus evident in the literature regarding many of these variables and their influence on economy supports the use of expanded sample sizes featuring both genders, standard testing conditions, and cross- and interdisciplinary approaches to help explain group economy differences observed in descriptive and experimental paradigms and to extend the generalizability of research findings.
Biomechanical considerations for economical walking and running.
It has been suggested that biomechanical factors play a role in explaining interindividual differences in movement economy, but it is not apparent how important this role is nor how consistently these factors explain such differences. The purpose of this review is to summarize our current state of knowledge regarding the relationships between gait economy and selected body structure and biomechanical factors. Because the research literature contains other review papers on this general topic, it is not the intent to provide a comprehensive analysis of all anatomical and biomechanical factors that have been examined previously. The review considers not only some topics of very recent interest (e.g., Does flexibility/joint range of motion affect gait economy? Can gait mechanics and economy be altered effectively via biomechanical feedback?), but also topics that have been examined considerably over many years (e.g., Is economy of motion associated with body mass, mass distribution, speed of movement, stride length and rate, and gait kinetics?). Results from the many studies reviewed confirm the notion that several structural and biomechanical factors offer some potential for explaining economy differences between individuals. Nevertheless, the relationships that have been observed between economy and individual descriptors of body structural and gait mechanics have generally been weak and inconsistent from study to study. Variables that describe muscular effort appear to have the greatest potential for explaining metabolic energy demands during walking and running. Unfortunately, at present it is unclear what quantifiable descriptors can best reflect muscle force production.
Cytosolic calcium ion and arachidonic acid release and metabolism in macrophages.
The aim of the present work was to elucidate the role of cytosolic calcium ions, [Ca2+]i, in the control of arachidonic acid release and metabolism. [Ca2+]i was measured in resident peritoneal rat macrophages loaded with Fura2, and compared with the release of leukotriene B4(LTB4) and prostaglandin l2 (PGL2, assayed through its hydrolysis product 6-keto-PGF1 alpha). The calcium ionophore A 23187 stimulated both an increase in [Ca2+]i and the release of LTB4 and 6-keto-PGF1 alpha. On the contrary, zymosan and opsonized zymosan, while stimulating eicosanoid release to an extent only slightly lower than A 23187, did not affect [Ca2+]i. Lipopolysaccharide stimulated 6-keto-PGF1 alpha, but not LTB4, release, without affecting [Ca2+]i. In parallel experiments, macrophages were prelabelled with [3H]arachidonic acid and the release of total 3H-products was assayed and taken as an index of phospholipase activity. A 23187, zymosan and opsonized zymosan increased the release of 3H-products in the presence of Ca2+. When extracellular Ca2+ was removed, the ionophore-induced 3H-products release was greatly blunted, while the release induced by zymosan was actually augmented. Our data indicate that a generalized [Ca2+]i increase is not necessary for arachidonic acid release and metabolism in rat peritoneal macrophages.
Eicosanoid production and phospholipase A2 secretion by peritoneal macrophages from rats with adjuvant-induced arthritis.
The effect of adjuvant-induced arthritis on rat peritoneal macrophage (RPM) function with respect to [14C]arachidonic acid (AA) release, leukotriene B4 (LTB4) and prostaglandin E2 (PGE2) production, and secreted phospholipase A2 (PLA2) activity was investigated. Twice as many cells were lavaged from the peritoneal cavity of arthritic rats 21 days post-adjuvant injection than were lavaged from normal rats. PGE2 production was increased two-fold in Ca++ ionophore-stimulated RPM from the adjuvant animals as compared with RPM from control animals. However, PLA2 secretion, LTB4 production and [14C]AA release were unchanged. These results suggest that PGE2 production, rather than LTB4 production or PLA2 secretion, is preferentially enhanced in Ca++ ionophore-stimulated RPM from arthritic rats and may, therefore, reflect a major role for PGE2 in adjuvant-induced arthritis. However, the presence of increase numbers of macrophages and their associated products, including PLA2 and LTB4, may also contribute to the inflammatory process in this disease.
Human papilloma virus and carcinoma of the laryngopharynx.
The presence of human papillomavirus (HPV) genomes 6, 11, 16 and 33 in 16 patients with laryngopharyngeal carcinomas was examined by means of a polymerase chain reaction. HPV genomes were detected in 75 per cent of cases. In hypopharyngeal carcinoma, HPV 6 and 11 were present in adjacent tissue but absent from the tumour. HPV 16 and 33 were present in 40 per cent of laryngeal tumours and adjacent tissue. These results suggest that HPV 16 and 33 may be closely associated with the development of some laryngopharyngeal carcinomas.
The microbiology of peritonsillar sepsis.
Pus obtained by needle aspiration of 91 peritonsillar abscesses was examined microbiologically. A positive culture was obtained in 55 patients (60 per cent). Sixty-four bacteriological isolates were grown. Forty patients had a pure growth of a single organism, of which 21 (53 per cent) were beta Haemolytic streptococci. Pure growths of Staphylococcus aureus were found in only three patients. Fifteen patients had mixed organisms, including anaerobes, in their pus and the resistance to penicillin was low. Only the bacteroides species were generally penicillin resistant. The vast majority of patients made a good recovery following needle drainage of the abscess and treatment with parenteral penicillin. The patients with a mixture of penicillin sensitive and penicillin resistant organisms also made a good clinical recovery following needle drainage and administration of parenteral penicillin. The relevance of these findings in the pathogenesis and management of peritonsillar sepsis is discussed.
The management of peritonsillar sepsis by needle aspiration.
172 consecutive patients admitted with suspected unilateral peritonsillar sepsis were studied. Needle aspiration of the peritonsillar space was performed, and they were all then treated with intravenous antibiotics (usually benzylpenicillin). Any pus obtained was cultured. The aspiration was repeated if the patient was not improving after 24 h. A quantity of pus was aspirated at the first attempt from 91 patients (53%); 82 of these required no further aspiration but 7 required a further single aspiration and 2 required a further 2 aspirations before resolution of the sepsis. 71 of the 81 patients (88%) from whom pus had not been aspirated, and who were therefore initially considered to have peritonsillar cellulitis, required no further aspirations. However, 6 subsequently drained pus spontaneously and 4 produced a positive aspirate on a second occasion. Four patients required a change in their antibiotic therapy. We have found the combination of needle aspiration and parenteral antibiotics to be an effective treatment of peritonsillar sepsis. All patients were spared the unpleasant and painful experience of an incision and drainage procedure.
Mood state and running economy in moderately trained male runners.
The purpose of this study was to determine the relationship between psychological states as measured by the Profile of Mood States (POMS) inventory and within-subject variation in running economy (RE) in moderately trained male runners (N = 10). Subjects (ages 20-34 yr) were monitored during treadmill running, five times a week (Monday through Friday) for 4 wk, at 2.68, 3.13, and 3.58 m, s-1. Tension, depression, anger, vigor, fatigue, confusion, and a total mood disturbance (TMD) score were assessed every Friday prior to the treadmill running sessions. Oxygen consumption (VO2) was determined via the open-circuit method during each of the three running paces. VO2 values were averaged over 5 d and three speeds for each week (RE) and were correlated with the weekly TMD scores, resulting in a nonsignificant group correlation of r = -0.28. The within-subject group correlation between TMD scores and RE was r = 0.88. This positive correlation indicates that, when the focus of attention was on within-subject variation, weeks featuring more economical values were associated with more positive mental health profiles. Correlations between average VO2 and the six POMS subscales were tension. r = 0.81; depression, r = 0.73; anger, r = 0.58; vigor, r = -0.60: fatigue, r = 0.18; and confusion, r = 0.60. All correlation coefficients except for fatigue were significantly (P less than 0.01) related to average VO2. In conclusion, it appears that short-term fluctuations in RE of moderately trained male runners are closely tied to their mood state.
Daily variation in running economy of moderately trained male runners.
The purpose of this study was to quantify total within-subject variation in running economy (RE) in moderately trained male runners (N = 10). Subjects (ages 20-34 yr) were monitored during treadmill running, five times a week (Mon-Fri) for 4 wk, at 2.68, 3.13, and 3.58 m.s-1. Oxygen consumption (VO2) was determined via the open-circuit method during each of the three running paces. Coefficients of variation among the three paces were not significantly (P greater than 0.05) different. An analysis of variance with repeated measures and a three-factor (3 x 4 x 5) design indicated that speed was the only significant (P less than 0.05) effect. Reliability tests performed on the data indicated that although there is an improvement in the percentage of variation accounted for as the number of tests conducted is increased, the benefit obtained by testing 5 d is very small when compared with testing 2 d. When effect sizes are used in the determination of subject numbers needed to detect significant effects, it is apparent that smaller anticipated effect sizes necessitate large sample sizes. In conclusion, RE appears to be a stable physiological measure in moderately trained male runners, and a criterion value based on the average of two measures per subject is recommended to obtain an acceptably stable RE value.
Variability in running economy and mechanics among trained male runners.
Data from two studies were analyzed to quantify intraindividual variability and reliability in running economy (RE) and mechanics. Following 30-60 min of treadmill accommodation, stride-to-stride and day-to-day biomechanical stability were assessed in 31 male runners (studies 1 and 2) who performed two level treadmill runs (3.33 m.s-1) at the same time of day, in the same footwear, and in a nonfatigued state. Under the same testing conditions, daily stability in RE was determined in 17 of the 31 subjects (study 2). RE demonstrated high day-to-day reliability (r = 0.95), and the mean coefficient of variation in RE was 1.32% (range = 0.30-4.40%). Stride-to-stride reliability for temporal (T), kinematic (KNM), and kinetic (KIN) measures was very high (mean r = 0.96; range = 0.91-0.99), but day-to-day reliability was lower for KIN (mean r = 0.67; range = 0.28-0.88) compared with T and KNM (mean r = 0.91; range = 0.68-0.98). Further analyses revealed no significant (P less than or equal to 0.05) mean stride-to-stride differences for any biomechanical variable, and only three of 22 variables (peak resultant velocity of the ankle joint, step length, and swing time) demonstrated statistically significant day-to-day differences. Viewed in concert, these results suggest that, if the testing environment is controlled, multiple trials are not required to obtain stable measures of running economy and basic mechanical characteristics in trained male runners if group data from adequate sample sizes are considered. However, if individual records are scrutinized or if small sample sizes cannot be avoided, at least two measures of individual performances should be secured.
Multiple pathways for signal transduction in the regulation of arachidonic acid metabolism in rat peritoneal macrophages.
The roles of guanine nucleotide-binding proteins (G-proteins) and cyclic AMP (cAMP) in signal-transduction of inflammatory stimuli leading to arachidonic acid metabolism in resident rat peritoneal macrophages (RPM) were investigated. Opsonized zymosan, targeting multiple receptors and latex particles coated with IgG (latex-IgG), targeting Fc receptors, were used as models of in vivo inflammatory stimuli encountered by macrophages. A comparison of the patterns of eicosanoid products produced in response to these stimuli showed differences: opsonized zymosan stimulated production of more leukotriene B4 (LTB4) than prostaglandin E2 (PGE2), while latex-IgG stimulated production of more PGE2 than LTB4. Non-selective stimulation of G-proteins by GTP and non-hydrolyzable analogs of GTP also stimulated arachidonic acid metabolism; these agents were not selective for PGE2 or LTB4 production. Cholera toxin, however, selectively stimulated production of PGE2 rather than LTB4 and also increased intracellular cAMP concentrations. The increased cAMP did not appear to mediate cholera toxin stimulation since forskolin, which also increased cAMP, was inhibitory to PGE2 production. This suggests that latex-IgG and cholera toxin may activate arachidonic acid metabolism through a G-protein other than Gs to induce PGE2 production specifically. The effects of pertussis toxin were biphasic: a partial inhibitory effect was observed at a low concentration of pertussis toxin (1 ng/ml) on opsonized zymosan or latrix-IgG stimulated arachidonic acid metabolism, while a high concentration of pertussis toxin (100 ng/ml) augmented the stimuli. A pertussis toxin-sensitive G-protein, possibly Gi, may therefore mediate a portion of the stimulatory signals. We have concluded that multiple pathways probably exist for opsonized zymosan and latex-IgG stimulation of arachidonic acid metabolism potentially involving multiple G-proteins.