Biomedical subjects

T S Hurst

Publications and source records attributed to T S Hurst.

24 records · Page 2Linked to original sources

PubMed1989

Importance of evaporative water losses during standardized nebulized inhalation provocation tests.

Evaporative water losses from jet nebulizers produce temperature drop, reduction in total nebulizer output with increased nebulization time, and increasing concentration of solute remaining in the nebulizer. These were documented and quantitated for the Wright nebulizer which is used for one histamine/methacholine inhalation test method. Indirect determination of nebulizer aerosol output, made by estimation of total sodium lost from the nebulizer, was about 25 percent of total output as determined by weight change. A similar tendency was seen for a De Vilbiss 40 nebulizer for both reduction in total nebulizer output with increasing duration of nebulization, and increased solute concentration remaining in the nebulizer. These data must be taken into account when standardizing inhalation provocation tests. Nebulizers should be calibrated under the same conditions that they are used during the test. Histamine and methacholine solutions should be discarded after a single use in the 2-min tidal breathing Wright nebulizer method.

Aerosols↗

PubMed1987

Evaluation of microwave-thawed canine plasma for transfusion.

Units of fresh-frozen canine plasma were thawed rapidly in a microwave oven, using a mean of 15.4 thawing periods of 10 seconds each. The activated partial thromboplastin times, the one-stage prothrombin times, concentrations of fibrinogen, factor-VIII coagulant activity, and von Willebrand factor antigen of microwave-thawed units were not significantly different from those measured in small aliquots of the same units thawed in a warm water bath (n = 5). Five dogs were given a unit of their own microwave-thawed plasma. During the 24 hours after infusion, no significant changes were measured in temperature, heart rate, or respiration rate. In addition, significant changes in PCV, total protein concentrations, estimates of platelet numbers, total RBC counts, total WBC counts, and differential WBC counts were not measured in blood specimens obtained before infusion and 24 hours after the infusion of microwave-thawed plasma.

Animals↗

PubMed1984

Fast vs. slow exhalation before O2 inhalation alters subsequent phase III slope.

We studied 10 symptom-free lifetime non-smokers and 17 smokers all with normal pulmonary function studies. All subjects performed single-breath N2 washout tests by either exhaling slowly ("slow maneuver") from end inspiration (EI) to residual volume (RV) or exhaling maximally ("fast maneuver") from EI to RV. After either maneuver, subjects then slowly inhaled 100% O2 to total lung capacity (TLC) and without breath holding, exhaled slowly back to RV. In the nonsmokers seated upright phase III slope of single-breath N2 test (delta N2/l) was lower (P less than 0.01) for the fast vs. the slow maneuver, but this difference disappeared when the subjects repeated the maneuvers in the supine position. In contrast, delta N2/l was higher for the fast vs. the slow maneuver (P less than 0.01) in smokers seated upright. For the slow maneuver, delta N2/l was similar between smokers and nonsmokers but for the fast maneuvers delta N2/l was higher in smokers than nonsmokers (P less than 0.01). We suggest that the fast exhalation to RV decreases delta N2/l in normal subjects by decreasing apex-to-base differences in regional ratio of RV to TLC (RV/TLC) but increases delta N2/l in smokers, because regional RV/TLC increases distal to sites of small airways obstruction when the expiratory flow rate is increased.

Adult↗

PubMedDate not supplied

Lazaroids--not nitric oxide synthetase inhibitors--improve hemodynamics after thermal injury in anesthetized guinea pigs.

Our objective was to study the effects of a lipid peroxidation inhibitor (U74389G) and nitric oxide synthetase inhibitor (NG-methyl-L-arginine) on hemodynamic stability in burn shock. The design was a prospective, placebo control, randomized, and masked multigroup study in a research laboratory of a university hospital. We used 24 guinea pigs (N = 24), and induced burn shock by a scalding thermal injury (75 degrees C) to 35% of their body surface area. Hemodynamics and gas exchange were observed for 90 minutes after the burn injury in the four groups: no burn, burn-control, burn-U74 (10 mg/kg U74389G), and burn-LNMA (20 mg/Kg NG-methyl-L-arginine). The percentage of mean arterial pressure, normalized for the initial value at 30 minutes after the burn injury, decreased in all groups over time but was not significantly different in any group. The normalized percentage of flow also decreased over time in all groups with the slope of the linear regression significantly less in the burn-U74 group (-0.32 95% CI, -0.05, -0.15) and the no burn group (-0.37 95% CI, -0.48, -0.26), compared with the burn-control group (-0.66 95% CI, -0.77, -0.56) and the burn-LNMA group (-0.66 95% CI, -0.77, -0.56). The slope of the linear regression for the normalized percentage of systemic vascular resistance was significantly more marked in the burn-control group (2.45 95% CI, 1.35, 3.54) and the burn-LNMA group (1.22 95% CI, 0.89, 1.55) compared with the no burn group (0.16 95% CI, 0.11, 0.44) or the burn-U74 group (0.34 95% CI, 0.06, 0.74). The burn shock resulted in hemodynamic instability as measured with increased systemic vascular resistance, decreased cardiac output, and mean arterial pressure. Use of a lazaroid (U74389G), not a nitric oxide synthetase inhibitor (NG-methyl-L-arginine), altered the clinical course after thermal injury. These data suggest the importance of lipid peroxidation and free radicals as secondary mediators in the evolution of burn shock.

Analysis of Variance↗

PubMedDate not supplied

The effects of U-74389G, a 21-aminosteroid, on pulmonary vascular resistance after a scald.

We tested U-74389G (C37H50N6O2-CH4O4), a 21-aminosteroid, to determine whether it ameliorates the pulmonary vascular effects of a surface scald. We studied 24-anesthetized rabbits mechanically ventilated with 100% and then 13% O2. Twelve rabbits received a scald (75 degrees C water applied to the shaved ventral surface for 90 seconds), and 12 served as control (20 degrees C water). Six control and six scalded animals additionally received U-74389G (5 mg/ kg intravenously). We measured hemodynamics and blood gases prescald, 30 minutes postscald, and 30 minutes after U-74389G or placebo administration. The strength of hypoxic pulmonary vasoconstriction (HPV) was assessed as the difference between pulmonary vascular resistance measured during 13% O2 ventilation and during 100% O2 ventilation. Hemodynamics and gas exchange were similar between groups. The strength of HPV was significantly diminished postscald, but U-74389G treatment restored HPV to baseline values. We conclude that a scald reduces the strength of HPV, and the response to U-74389G suggests this may be mediated by free radicals.

Animals↗

PubMedDate not supplied

Predictors of longitudinal changes in pulmonary function among swine confinement workers.

OBJECTIVE: To determine predictors of longitudinal changes in pulmonary function in swine confinement workers. DESIGN: Longitudinal study conducted from November 1989 to June 1991 and January 1994 to May 1995. SETTING: Swine confinement workers in Saskatchewan. PARTICIPANTS: Forty-two swine confinement workers who were studied in 1989/90 and studied again in 1994/95. RESULTS: Of 98 male swine confinement workers (mean age SD 36.3 11.1 years) studied at baseline, 42 were studied again five years following. Complete information on baseline across-shift pulmonary function (preshift forced expiratory volume in 1 s [FEV1], forced vital capacity [FVC], and every 2 h FEV1 and FVC during the shift), and five-year follow-up pulmonary function (with FEV1 and FVC) were available on all 42 subjects. Mean across-shift changes (preshift measurement to last measurement of the day) at baseline were -159. 8 61.7 mL in FEV1 and -35.3 65.6 mL in FVC. Mean annual rate change between baseline and follow-up for FEV1 was -53.9 61.7 mL/year and for FVC -48.9 71.6 mL/year. After adjusting for age, height, smoking and hours spent in the barn, the baseline across-shift change in FEV1 and FVC was a significant predictor of annual rate change in FEV1 (P=0.01) and FVC (P=0.02), respectively. To determine the effects of indoor air quality on longitudinal lung function decline, indoor air environmental measurements were analysed. Complete information on respiratory health and indoor air quality was available on 34 of the 42 subjects. Assessment of indoor environment of swine barns included a summer and winter measurement for airborne dust, gases and endotoxin levels. After adjusting for age, height, smoking, ammonia and hours spent in the barn, the endotoxin level (Eu/mg)was a significant predictor of annual rate change for FEV1 but not FVC. CONCLUSIONS: These results suggest that shift change is an important predictor of longitudinal changes in lung function in swine confinement workers and that endotoxin exposures may mediate annual decline in FEV1 in these workers.

Adolescent↗