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Biomedical subjects

J Loke

Publications and source records attributed to J Loke.

At least 37 records · Page 2Linked to original sources
PubMed1984

Rabbit lung after acute smoke inhalation. Cellular responses and scanning electron microscopy.

The cellular responses in the lungs of rabbits and the morphologic features of the tracheobronchial tree by scanning electron microscopy were examined 24 hours following acute inhalation of Douglas fir wood smoke. Thermal injury to the upper airway was excluded. Injury to proximal tracheal lining cells was severe and consisted of loss of the epithelium. The changes of the epithelial barrier in the proximal major bronchi were less severe in nature. However, the alterations observed by scanning electron microscopy suggested dysfunction of the mucociliary blanket. Both cell counts of bronchoalveolar lavage fluid and morphologic findings reflected an increase in alveolar macrophage response. Smoke-exposed alveolar macrophages showed significant changes in the surface features. These findings may explain the tracheobronchitis seen clinically, and the propensity of patients to lung infection following smoke inhalation.

Acute Disease↗
PubMed1984

Influence of exercise on urea, creatinine, and 3-methylhistidine excretion in normal human subjects.

To evaluate the effects of exercise on net protein catabolism, the losses of urea in sweat and urine and urinary creatinine and 3-methylhistidine (3MH) excretion were determined in eight healthy subjects during cycle ergometer exercise performed at approximately 45% of VO2max for 90 min. The subjects ingested a meat-free diet for 5 days starting 3 days before and continuing for 1 day after the day of exercise. During exercise, total urea excretion (urine + sweat losses) increased 100% above pre- and postexercise values. Thirty percent of the total urea excretion during exercise was in the form of sweat losses. Total protein breakdown (as reflected by urea excretion), however, could account for less than 5% (21 +/- 4 kcal) of total calorie expenditure during the exercise (567 +/- 83 kcal). Urinary creatinine excretion increased by 50% during exercise. Urinary excretion of 3MH also tended to rise, but the ratio of urinary 3MH to creatinine showed no change in response to exercise. We conclude that 1) light to moderate exercise results in an increase in net protein catabolism and an increase in creatinine excretion; 2) sweat losses are an important route for urea excretion during exercise; 3) there is no evidence of a disproportionate increase in breakdown of myofibrillar contractile proteins; and 4) in spite of the increase in the rate of protein catabolism, protein is only a minor source of energy during light to moderate exercise.

Adolescent↗
PubMed1984

Right ventricular performance and central circulatory hemodynamics during upright exercise in patients with chronic obstructive pulmonary disease.

A combined hemodynamic and radionuclide approach was used to evaluate right ventricular performance during upright exercise in 12 male patients with chronic obstructive pulmonary disease. To assess the influence of intrathoracic pressure on hemodynamic parameters, pleural pressure was measured using an esophageal balloon. Mean age was 58.5 +/- 6.7 yr (+/- SD), and all had dyspnea on physical exertion. For the group, forced expiratory volume in one second (FEV1) was 1.04 +/- 0.40 L and arterial oxygen-tension (PaO2) was 77 +/- 11 mmHg. During steady-state, upright exercise on the bicycle ergometer at 58% of maximal oxygen consumption (VO2 max): (1) mean pulmonary artery pressure (Ppa) and pulmonary vascular resistance index (PVRI) increased significantly; (2) right ventricular ejection fraction (RVEF) failed to augment appropriately (less than 5% increase); and (3) right ventricular end-diastolic volume index (RVEDVI) increased significantly, whereas right ventricular end-systolic volume index (RVESVI) did not change. A diminished pulmonary vascular bed, the change in PaO2, and possibly increased alveolar pressure appeared to contribute to the increased load placed on the right ventricle. Both RVEDVI and RVESVI were significantly correlated with Ppa at rest and during exercise. In 2 of the 12 patients, stroke volume index and left ventricular end-diastolic volume index showed minimal change with exercise. VO2max was correlated with the FEV1 (r = 0.75; p = 0.01) as well as resting (r = -0.60; p = 0.02) and exercise (r = -0.61; p = 0.02) PVRI. These results suggest that exercise performance may be limited by right ventricular dysfunction in addition to respiratory impairment in some patients with chronic airway disease.

Aged↗
PubMed1984

Progressive immune failure in dyskeratosis congenita. Report of an adult in whom Pneumocystis carinii and fatal disseminated candidiasis developed.

Community-acquired Pneumocystis carinii pneumonia developed in a young adult patient with dyskeratosis congenita. His hospitalization ended fatally with disseminated candidiasis. Evaluation during the admission showed evidence of cellular immune dysfunction as indicated by skin test anergy and absent lymphocyte proliferation in an in vitro mixed lymphocyte culture. Treatment with transfer factor failed to reverse the cutaneous anergy or affect the clinical course. Dyskeratosis congenita is a rare multisystem disorder with prominent dermatologic manifestations; bone marrow failure or malignant neoplasm are common fatal outcomes. Immune system abnormalities are not classically considered a part of the disease complex. Serial evaluation of our patient's condition over several years suggests that depressed immune function, especially of the cellular limb, may evolve as a feature of clinical importance in these patients.

Acquired Immunodeficiency Syndrome↗
PubMed1984

Exercise impairment in chronic obstructive pulmonary disease.

This article reviews factors that may limit exercise performance in patients with COPD. These factors include alteration in pulmonary mechanics, respiratory muscle fatigue, impairment in pulmonary gas exchange, abnormal perception of breathlessness and ventilatory control, cor pulmonale, and poor nutritional status. The clinical application of exercise testing in patients with COPD and the role of various therapeutic modalities in altering exercise performance in COPD are discussed.

Diaphragm↗
PubMed1984

Exercise testing in occupational lung diseases.

The authors discuss the value of exercise testing in two areas of importance in occupational pulmonary disease: (1) the surveillance of worker populations in order to gain epidemiologic and physiologic understanding of disease and (2) the assessment of work capacity in individual patients.

Asbestosis↗
PubMed1984

The physiology of endurance exercise. The marathon.

The metabolic demands of competitive marathon running require the development and integration of the respiratory, cardiovascular, and musculoskeletal systems. Environmental factors such as ambient temperature, humidity, and wind resistance can affect running performance. In addition to training, racing strategy, fluid ingestion, and dietary manipulation are specific and practical methods that can be used to augment marathon performance.

Adolescent↗
PubMed1983

Positional dyspnea and oxygen desaturation related to carcinoma of the lung. Up with the good lung.

Body position can lead to respiratory symptoms and affect gas exchange in disease states. We describe a patient with carcinoma of the left lung in whom dyspnea and oxygen desaturation developed in the right lateral position only. Fiberoptic bronchoscopic study demonstrated a tumor mass protruding into the left main-stem bronchus, which caused further narrowing when the patient turned on his right side.

Bronchoscopy↗
PubMed1982

Improvement in cardiac performance by oral long-acting theophylline in chronic obstructive pulmonary disease.

Although oral theophylline is a widely used bronchodilator in chronic obstructive pulmonary disease (COPD), its effects upon cardiac performance have not been fully established. The effect of slow release oral theophylline upon right ventricular and left ventricular ejection fraction was evaluated using first-pass quantitative radionuclide angiocardiography in 15 patients with COPD. After 72 hours of therapy, oral theophylline significantly increased right ventricular ejection fraction (42% to 48%, p less than 0.005). In 7 of 10 patients with depressed baseline right ventricular performance, including two with cor pulmonale, right ventricular ejection fraction normalized (greater than or equal to 45%). After long-term therapy, an average of 16 weeks, right ventricular fraction also increased (43% to 48%, p less than 0.005). Left ventricular ejection fraction improved significantly from 64% to 68% (p less than 0.05) at 72 hours and from 61% to 65% (p less than 0.025) after long-term therapy. These data indicate that oral theophylline produces a sustained modest enhancement of resting biventricular performance in COPD.

Administration, Oral↗
PubMed1982

Ventilatory responses at rest and during exercise in marathon runners.

Diminished ventilatory responsiveness to hypercapnia and hypoxia has been reported in athletes, but whether reduced chemosensitivity might lessen hyperpnea during exercise and facilitate performance is unknown. To evaluate ventilatory control and its possible role in athletic performance, we prospectively measured ventilatory responses to hypercapnia and hypoxia at rest and ventilatory equivalents for carbon dioxide (VE/VCO2) and oxygen (VE/VO2) during exercise in 20 accomplished marathon (42.2 km) runners (RUN) and 20 control subjects (CON). The athletes (mean age 27.8, range 18-41 yr) were all experienced runners with a mean best marathon time of 2 h, 36 min (range 2:14-2:55). There were no significant differences in the ventilatory responses at rest to hypercapnia (RUN, 2.23 +/- 0.73 vs. CON, 2.61 +/- 1.05 l X min-1 X Torr-1) and hypoxia (RUN, 0.57 +/- 0.40 vs. CON, 0.88 +/- 0.72 l X min-1 X 1% desat-1) (mean +/- SD). Similarly, there were no significant differences in VE/VCO2 and VE/VO2 between the two groups. Good correlation (r = 0.68; P less than 0.01) was observed between hypercapnic response at rest and exercise ventilation (VE/VCO2) in RUN. However, both hypercapnic and hypoxic ventilatory responses correlated poorly with marathon running time. These results demonstrate no differences in ventilatory responses at rest and during exercise between marathon runners and control subjects. The range of ventilatory responsiveness observed in this group of marathon runners indicates that a spectrum of ventilatory control is present in well-trained endurance athletes.

Adult↗
PubMed1982

Respiratory muscle fatigue after marathon running.

Respiratory muscle fatigue has been demonstrated in the laboratory as well as in pathological states, but whether it occurs in healthy individuals under physiological conditions is unknown. To determine whether fatigue of the respiratory muscles may develop with endurance exercise, we measured spirometry and respiratory muscle strength and endurance in four runners before and after completion of a marathon race (42.2 km). Strength was assessed by measuring maximal inspiratory (PImax) and expiratory (PEmax) pressures and transdiaphragmatic pressure during inspiratory capacity (PdiIC); endurance was determined by measuring maximal voluntary ventilation (MVV). After marathon running (mean time, 3 h 24 min) there was no change in forced vital capacity, inspiratory capacity, or flow rates from prerace values. Decreases were observed between pre- and postrace PImax (165.8 +/- 11.0 vs. 138.5 +/- 7.6 cmH2O; P less than 0.01) PEmax (240.0 +/- 20.4 vs. 173.0 +/- 22.6 cmH2O; P less than 0.05), PdiIC (78.8 +/- 11.6 vs. 63.3 +/- 7.0 cmH2O; P less than 0.10), and MVV (178 +/- 24.2 vs. 161.2 +/- 23.2 l/min; P less than 0.005). The decrements in respiratory muscle strength and endurance suggest the development of respiratory muscle fatigue after marathon running.

Adult↗
PubMed1981

Helium-oxygen flow-volume curves in detecting acute response to hair spray.

The acute effect of hair spray on small airway function was studied in 11 healthy subjects by recording maximum expiratory flow-volume (MEFV) curves while the subjects were breathing first air (Ar) and then a 80% helium-20% oxygen mixture (He). The flow rate response of breathing He compared to Ar (delta MEF50) at 50% of the control forced vital capacity (FVC), and the point of identical flow on Ar and He MEFV curves, known as volume of isoflow (VisoV) were measured. Eight of 11 subjects reacted to the hair spray by demonstrating a decrease in the MEF50 and delta MEF50 although the difference was not significant. However, there was a significant increase in VisoV at 12,20 and 30 min post exposure. VisoV may be a sensitive index in detecting small airway dysfunction following acute exposure to hair spray.

Adult↗