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Biomedical subjects

D W Morgan

Publications and source records attributed to D W Morgan.

At least 109 records · Page 6Linked to original sources
PubMed1988

Clinicopathological study of myoepithelial sialadenitis and chronic sialadenitis (sialolithiasis).

To determine any overlap in pathological features between myoepithelial sialadenitis and chronic sialadenitis/sialolithiasis histological sections from 69 cases of myoepithelial sialadenitis (MESA) (n = 7) and chronic sialadenitis/sialolithiasis (n = 62) were reviewed over a 10 year period. Three of the cases with MESA contained calculi and four of those originally diagnosed as chronic sialadenitis/sialolithiasis showed epimyoepithelial island formation. The presence of calculi should not rule out a diagnosis of MESA, particularly in the parotid gland where calculi are uncommon; as the incidence of MESA may very well be underestimated and diagnosed as chronic sialadenitis, these patients, who are at increased risk of developing lymphoma, could be lost to follow up.

Adult↗
PubMed1988

Guilty but mentally ill: the South Carolina experience.

Thirty of the first 45 individuals to receive guilty but mentally ill (GBMI) verdicts in South Carolina were interviewed using a structured interview schedule for diagnosis. The relationship of diagnosis to pretrial evaluation and posttrial conviction treatment are discussed. No person received GBMI in a jury trial. Suggestions to improve the operation of the GBMI verdict are made, as well as a brief review of these data with data from other states.

Adolescent↗
PubMed1987

Sodium-calcium exchange in sarcolemmal vesicles from tracheal smooth muscle.

Sarcolemmal vesicles prepared by a new procedure from bovine tracheal smooth muscle were found to have a Na-Ca exchange activity that is significantly higher than that reported for different preparations from other types of smooth muscle. The exchange process system co-purified with 5'-nucleotidase, a plasma membrane marker enzyme, and was significantly enriched (over 100-fold) compared to mitochondria (cytochrome-c oxidase) but only slightly enriched (4-fold) compared to sarcoplasmic reticulum (NADPH-cytochrome-c reductase). The Na+ dependence of Ca2+ transport was demonstrated through both uptake and efflux procedures. The uptake profile with respect to Ca2+ was monotonic with a linear vo VS. vo.S-1 plot. The resultant Km of Ca2+ from the airway sarcolemmal vesicles (20 microM) was similar in magnitude to the Km of cardiac sarcolemmal vesicles (30 microM). Tracheal vesicles demonstrated a Vmax of 0.3-0.5 nmol.mg-1.s-1 which is significantly higher than that reported in preparations from other smooth muscle types. Furthermore, two processes found to stimulate cardiac Na-Ca exchange, pretreatment with either a mixture of dithiothreitol and Fe2+ or with chymotrypsin, were ineffective on the tracheal smooth muscle. Thus, the Na-Ca exchanger identified in tracheal smooth muscle appears to be different from that observed in cardiac muscle, implying that regulation of this activity may also be different.

5'-Nucleotidase↗
PubMed1987

Effects of respiratory muscle endurance training on ventilatory and endurance performance of moderately trained cyclists.

This study examined the effects of respiratory muscle endurance training (RMET) on ventilatory and endurance performance among moderately trained, male cyclists. Nine subjects initially completed two cycling VO2 max tests, two endurance cycling tests for time at 95% VO2 max, a 15-s MVV test, and an endurance breathing test for time at 100% MVV. Four subjects then underwent 3 weeks of strenuous RMET while five served as controls. Mean posttest 15-s MVV and endurance breathing time were significantly higher in the RMET group (243 +/- 14 l X min-1 and 804 +/- 94 s) than in the control group (205 +/- 6 l X min-1 and 48 +/- 8 s). No significant group differences in VO2 max or endurance cycling time at 95% VO2 max were observed following RMET. Results of this exploratory study indicated that RMET improved ventilatory power and endurance, but did not alter VO2 max or endurance cycling performance among moderately trained, male cyclists.

Adult↗
PubMed1987

Modulation of rabbit airway smooth muscle responsiveness by respiratory epithelium. Involvement of an inhibitory metabolite of arachidonic acid.

The integrity of the respiratory epithelium may be important in development of bronchial hyperreactivity; however, the mechanisms involved remain unknown. This study was undertaken to determine if epithelium of rabbit intrapulmonary bronchi is capable of modulating the responsiveness of airway smooth muscle to a pharmacologic stimulus, and whether epithelial-derived prostaglandins play a role in this modulatory function. Mechanical removal of the epithelium from bronchial segments, or incubation of intact bronchi with indomethacin (an inhibitor of prostaglandin synthesis) increased the sensitivity of bronchial smooth muscle to bethanechol. Cyclooxygenase was localized within mucosal epithelial cells of intact airways by avidin-biotin immunoperoxidase staining using a monoclonal antibody to the enzyme. Removal of the epithelium significantly reduced the levels of PGE2 and 6-keto-PGF1 alpha accumulated in the media surrounding bronchial explants. In epithelium-intact bronchi precontracted with bethanechol, arachidonic acid evoked an indomethacin-sensitive relaxation response comparable to relaxation induced by exogenous addition of PGE2. Although PGE2 evoked similar responses in epithelium-denuded bronchi, arachidonic acid-induced relaxation responses were negligible. The results suggest epithelial cells of rabbit bronchi modulate the responsiveness to pharmacologic stimuli by production and release of an inhibitory cyclooxygenase metabolite of arachidonic acid.

Animals↗
PubMed1987

Physiological responses of triathletes to maximal swimming, cycling, and running.

The objectives of this study were to: (a) develop a physiological profile for a group of trained triathletes and (b) determine whether multiple modes of training result in general or specific adaptations. VO2max of 13 trained triathletes (mean = 29.5 yr) was measured during treadmill running (TR), cycle ergometry (CE), and tethered swimming (TS) over a 6-wk period encompassing a half-triathlon (1.2 mile swim/56 mile bike/13.1 mile run). Most subjects performed two tests in each mode. Since test-retest reliability coefficients for TR, CE, and TS VO2max were 0.97, 0.93, and 0.97, respectively, results were averaged: formula; see text The mean TR VO2max indicated that the subjects were well-trained, but not of elite caliber. Mean CE VO2max was 95.7% of the TR value, which is greater than the value typically found in non-cyclists (88 to 92%) but less than that of highly trained cyclists (98 to 105%). Mean TS VO2max was 86.6% of the TR value. As in cyclists, this percentage is greater than that of recreational swimmers (78 to 82%) but less than that of elite swimmers (93 to 95%). Running and cycling times in the triathlon were significantly (P less than 0.01) related to the corresponding VO2max values (r = -0.68 and r = -0.78, respectively), but swimming times were not (r = -0.50). It is concluded that these triathletes were well-trained in all events, but not to the same extent as athletes who train in only one sport. Running and cycling performance were associated with VO2max.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1986

Growing calmodulin crystals for X-ray diffraction studies at room temperature in 2 days.

Crystals of bovine brain calmodulin have been grown using a novel procedure which utilizes a mixture of alcohols as a precipitant. Crystals were grown by vapor diffusion at room temperature in the presence of 15% ethanol, 25% 2-methyl-2,4-pentanediol, 5.0 mM calcium chloride, and 10.0 mM sodium acetate buffer at pH 4.0. Crystals were visible within 4 h and grew to 0.75 X 0.3 X 0.125 mm in 2 days, without seeding. The crystals of calmodulin are isomorphous with those found by W. J. Cook, J. R. Dedman, A. R. Means, and C. E. Bugg (1980, J. Biol. Chem. 255, 8152-8153). The protein crystallizes in space group P1 with unit cell dimensions a = 29.92 A, b = 55.96 A, c = 24.75 A, alpha = 93.81 degrees, beta = 99.24 degrees, and gamma = 88.40 degrees.

Alcohols↗
PubMed1986

Specific in vitro activation of Ca,Mg-ATPase by vitamin D-dependent rat renal calcium binding protein (calbindin D28K).

The vitamin D-dependent, calcium-binding protein from rat kidney, calbindin D28k (renal CaBP) specifically stimulates Ca,Mg-ATPase activity of human erythrocyte plasma membranes in a dose-dependent, calcium-sensitive manner. This stimulation was about two-fold compared to a three-fold stimulation by calmodulin. The effect was specific since other calcium-binding proteins and low molecular weight proteins did not stimulate Ca,Mg-ATPase activity. Renal CaBP did not stimulate cyclic nucleotide phosphodiesterase at concentrations greater than those which stimulated Ca,Mg-ATPase activity. This is the first report of a specific in vitro effect of renal CaBP on an enzyme system.

Animals↗
PubMed1986

Effect of dextromethorphan on guinea pig ileal contractility in vitro: comparison with levomethorphan, loperamide and codeine.

Dextromethorphan (DM) was tested for its effect on the contractility of the guinea pig ileum in vitro. Comparisons were made with levomethorphan, levorphanol, codeine and loperamide. DM and codeine inhibited the contractions of the electrically stimulated ileum, with IC50 values of 15 and 8 microM, respectively. The inhibitory effect of DM, in contrast to codeine, was not blocked by the opiate antagonist naloxone. Pretreatment (8, 50 and 100 microM) with DM and its I-isomer levomethorphan reduced in a dose-dependent fashion both phasic and tonic contractions produced by maximally effective concentrations of carbachol and 80 mM KCl. Pretreatment (8, 50 and 100 microM) with codeine, dextrorphan or levorphanol, unlike DM, did not reduce carbachol or KCl-induced contractions. The concentration-response curves to calcium in K+ depolarized ileum were shifted to the right in a parallel manner suggesting competitive antagonism for DM (pA2 5.3), levomethorphan (pA2 5.3) and loperamide (pA2 6.6). Codeine and levorphanol (8, 50 and 100 microM) did not antagonize calcium-induced contractions. In two assays of calmodulin-dependent processes DM was inactive (IC50 greater than 1 mM), whereas trifluoperazine and calmidazolium (standard calmodulin antagonists) were active in the micromolar range. In summary, these data suggest that DM, through a nonopiate mechanism, antagonizes gut contractility possibly by "stabilizing" neuronal and/or muscle cell membranes.

Actins↗
PubMed1986

Effects of stride length alteration on racewalking economy.

This study investigated the effects of stride length (SL) manipulation on racewalking economy in 7 competitive racewalkers. Following two test sessions in which VO2 max and freely-chosen stride length (FCSL) were determined, each subject completed 6-min racewalking bouts at five randomly-ordered SL conditions (FCSL and -10%, -5%, +5%, and +10% of leg length from the FCSL) while walking at a velocity approximately equal to their 10 km training pace. Actual and predicted group mean VO2 values for the five SL conditions indicated that the subjects were most economical walking at the FCSL, with progressively higher energy costs manifested at the +5% and -5% and the +10% and -10% leg length conditions, respectively. A mean absolute difference in VO2 of 0.6 ml X kg-1 X min-1 was observed between subjects' FCSL and optimal SL. Linked with this deviation in VO2 was a mean absolute SL difference of 3.2 cm (3.6% of mean leg length). These data support the hypothesis that trained subjects select locomotion patterns that are nearly optimal in terms of the aerobic demands.

Adolescent↗
PubMed1985

Treatment of theileriosis with parvaquone in Zambia.

Parvaquone was used to treat 126 cattle with theileriosis. Theileria species schizonts were present in their lymph node biopsy smears and the majority of the animals had clinical signs of theileriosis. One hundred and fifteen treated and one untreated cattle survived the infection while 11 treated and 12 untreated animals died of the disease. Despite serological evidence of a parasite challenge during the subsequent rainy season, recovered cattle did not develop clinical signs of theileriosis but untreated cattle in the area continued to die from the disease. An intermittent low piroplasm parasitaemia (less than 1 per cent) was observed in recovered cattle for up to 14 months after detailed monitoring of cattle in the trial; this could be evidence for a carrier status for the Theileria species or strains involved.

Animals↗
PubMed1985

Posterior fossa subdural empyema.

Seven cases of posterior fossa subdural empyema were treated between 1955 and 1984; 3 of the patients survived. The two sources of infection were otogenic and spread from supratentorial subdural empyema complicating acute frontal sinusitis. Investigations including computerized axial tomography (CT) scans were sometimes equivocal and diagnosis was sometimes delayed. Posterior fossa craniectomy appeared to be the operation of choice; all the patients treated only by posterior fossa burr holes died. Early aggressive surgical intervention in such cases should result in a minimal morbidity.

Adolescent↗
PubMed1985

Treatment of Theileria annulata infection in calves with parvaquone.

Fifteen calves were infected by the injection of stabilate of a suspension of Hyalomma anatolicum anatolicum ticks infected with the Ankara strain of Theileria annulata. Three were kept untreated, as controls, and they all died of theileriosis. Three groups of four calves were treated intramuscularly with parvaquone (Clexon; Wellcome) when early signs of theileriosis were clinically apparent. One group received 20 mg (kg bodyweight)-1 of parvaquone 10 days after infection. Two of these calves were clinically cured and two died of theileriosis. The remaining two groups of four calves received two doses of parvaquone, each of 10 mg (kg bodyweight)-1, either on days 10 and 11 or days 10 and 12. Three calves in each group were clinically cured while one in each group died of theileriosis. Total parasitological cure was not achieved in any of the calves. No symptoms of toxicity due to parvaquone treatment were observed.

Animals↗