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Biomedical subjects

S J Jennings

Publications and source records attributed to S J Jennings.

11 recordsLinked to original sources
PubMed1992

Physiological cost index of paraplegic locomotion using the ORLAU ParaWalker.

Energy expenditure is an important parameter in the assessment of gait and orthotic treatment of locomotor disabilities. Up until now oxygen uptake measurement has been the most common method used to assess this. In able bodied subjects heart rate monitoring is also increasingly used. In high thoracic level lesion paraplegics monitoring heart rate was considered to be unreliable because of suspicion of injury to the sympathetic contribution to the cardiac plexus. Bar-On & Nene found that in paraplegics below the lesion level T3 heart rate still shows linear relation to oxygen uptake. MacGregor combined the heart rate and speed of locomotion to produce a single index called physiological cost index. This study consists of monitoring heart rate and speed of 16 adult thoracic level paraplegics walking with the ORLAU ParaWalker, calculation of their physiological cost index, and establishing a range of physiological cost index of paraplegic locomotion using the ORLAU ParaWalker.

Adult↗
PubMed1989

Hybrid paraplegic locomotion with the ParaWalker using intramuscular stimulation: a single subject study.

Functional intramuscular electrical stimulation of the gluteus maximus and gluteus medius on the stance side whilst walking is reported. The subject was an adult, male, post-traumatic complete paraplegic with lesion level at T7. He had been using surface stimulation to aid his walking with the adult ParaWalker Orthosis but suffered unpleasant anterior abdominal wall muscle contractions with high amplitude stimulation. The experimental use of percutaneous intramuscular Platinum/Iridium wire electrodes demonstrated that more forceful contractions of the buttock muscles could be achieved without any effect on abdominal wall musculature. This prompted the use of a permanent, implanted system. The system is inductively coupled to an external control device and is working satisfactorily 7 months after implantation.

Adult↗
PubMed1987

Airway caliber and the work of breathing in humans.

Mechanical work rate of breathing was measured in five normal subjects during voluntary eucapnic hyperventilation at rates of approximately 10, 20, 40, 60, and 80 l/min before and after inhalation of 1 mg of ipratropium bromide, an anticholinergic agent. Chest wall recoil pressure was measured over a range of lung volumes in each subject and was used as the reference pressure in the calculation of work rate. There was little change in elastic or resistive work rate at rest when vagal tone was reduced by ipratropium. The mean work at 40, 60, and 80 l/min was 8.9, 17.2, and 34.0 cmH2O.l-1.s before and 5.6, 12.4 and 25.8 cmH2O.l-1.s after ipratropium. This suggests that vagal tone significantly influences the work of breathing at high ventilatory rates, such as occur during strenuous exercise.

Adult↗
PubMed1984

Behavioral efficacy of haloperidol and lithium carbonate. A comparison in hospitalized aggressive children with conduct disorder.

The efficacy and safety of haloperidol, lithium carbonate, and placebo were critically assessed in 61 treatment-resistant, hospitalized children aged 5.2 to 12.9 years with diagnoses of conduct disorder, aggressive type. In this double-blind and well-controlled study, the optimal dosages of haloperidol ranged from 1.0 to 6.0 mg/day and those of lithium carbonate from 500 to 2,000 mg/day. For the assessment of behavioral changes and untoward effects, various rating scales were used in different settings. Both haloperidol and lithium carbonate were found to be significantly superior to placebo in decreasing behavioral symptoms. Although both medications were clinically effective, haloperidol was associated more often with untoward effects than was lithium carbonate.

Aggression↗
PubMed1984

Effect of adrenergic and vagal blockade on the normal human airway response to exercise.

Ten normal, non-asthmatic subjects performed an 18 min graduated exercise test on a static exercise bicycle on 3 separate days. They received either no medication, or propranolol 80 mg orally 2 h before, or ipratropium bromide 0.216 mg by inhalation 30 min before, the start of exercise. With no medication, transpulmonary index (TPI), a measure of airway resistance, fell linearly during exercise from a resting value of 0.269 +/- 0.024 to 0.170 +/- 0.014 kPa X 1(-1) X s by the end of exercise. This returned to baseline between 2 and 4 min after stopping exercise. Propranolol elevated baseline TPI slightly from 0.270 +/- 0.024 to 0.294 +/- 0.024 before exercise and during exercise this fell linearly to 0.185 +/- 0.016 kPa X 1(-1) X s. The fall in TPI during exercise after propranolol was not significantly different from the fall seen with no medication. Six minutes after exercise stopped TPI rose to 0.336 +/- 0.035 kPa X 1(-1) X s after propranolol. All values for TPI from 4 min to 16 min after exercise were significantly higher after propranolol than the corresponding values found after no medication (P less than 0.05). Ipratropium bromide decreased baseline TPI from 0.264 +/- 0.024 to 0.163 +/- 0.013 kPa X 1(-1) X s (P less than 0.001) and this did not change significantly further either during or after exercise. Normal subjects show considerable airway dilatation during exercise and this appears to result from inhibition of resting vagal tone. The sympathetic system does not appear to mediate the airway dilatation during exercise, but it may be important in protecting against post-exercise bronchoconstriction.

Adult↗
PubMed1983

The effect of increased lung volume on the expiratory rate of rise of alveolar carbon dioxide tension in normal man.

The rate at which alveolar PCO2 (PA, CO2) rises during expiration has been measured in seven healthy medical students. PA, CO2 rate of rise [delta PA, CO2/delta t] was measured by a method utilizing constant expiratory flow rates in individual breaths in two subjects, and was calculated from airway PCO2 and expiratory tidal volume in the remaining five subjects. Steady-state runs were recorded at two or more metabolic rates with the subject making no special effort to control mean lung volume. This was done to establish the relationship between delta PA, CO2/delta t and the rate of CO2 production (VCO2) at normal lung volume in individual subjects. Steady-state runs were also recorded at high lung volume. In each subject delta PA, CO2/delta t was less than would have been obtained at normal lung volume. Inversion of a hypothetical relation between delta PA, CO2/delta t, VCO2 and average lung volume (VLa; DuBois, Britt & Fenn, 1952) yielded calculated values of VLa for both the normal and the high lung volume states. Lung gas volume was measured in a whole body plethysmograph, ('box volume') both for the normal and high lung volume states, in each subject. Mean VLa and 'box volume' estimates showed only moderately good agreement, whereas the estimated differences between normal and high lung volume obtained by the two methods were virtually identical. These experiments suggest that the expiratory PA, CO2 rate of rise is determined, in the steady state, partly by the rate of CO2 production (a directly proportional relationship) and partly by the mean lung volume (an inversely proportional relationship).

Carbon Dioxide↗
PubMedDate not supplied

Vitreous fluorophotometry in patients with no or minimal diabetic retinopathy.

Vitreous fluorophotometry was used to estimate fluorescein leakage into the posterior vitreous of 20 insulin-dependent diabetic patients with no or minimal diabetic retinopathy 60 min after intravenous administration of 14 mg X kg-1 fluorescein. The permeability coefficient (p), a measure of fluorescein penetration through the blood-retinal barrier (BRB) into the vitreous, and the diffusion coefficient (D), a measure of fluorescein dispersion within the vitreous, were obtained by fitting a mathematical model to the vitreous fluorescence scan and plasma free fluorescence curve. A permeability index (PI) was also derived by dividing the area under the fluorescence scan by the area under the plasma free fluorescence time curve. The fluorescence concentrations at discrete distances from the retina were also noted. The mean +/- SD for p, D, and PI were 1.95 +/- 1.03 cm X s-1 X 10(-7), 1.74 +/- 1.53 cm2 X s-1 X 10(-5), and 2.14 +/- 1.21 cm X s-1 X 10(-7), respectively, and were not significantly different from values determined in normal subjects. Diabetic patients and normal subjects also had similar fluorescence measurements at corresponding distances from the retina. Quantitative indices of fluorescein leakage did not correlate with either the microaneurysm counts on fluorescein angiograms or the duration of diabetes. Vitreous fluorophotometry did not detect any abnormality of the BRB in diabetic patients with no or minimal retinopathy on fluorescein angiography.

Adolescent↗