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Biomedical subjects

M Gleeson

Publications and source records attributed to M Gleeson.

At least 145 records · Page 8Linked to original sources
PubMed1985

The relationship between atopy and salivary IgA deficiency in infancy.

In a prospective study, infants born to atopic parents had a significantly higher prevalence of salivary IgA deficiency at all ages studied than control infants, and the mean non zero IgA level of the potentially atopic infants was significantly lower at 8 and 12 months than of control infants. Of the infants with atopic parents, the prevalence of IgA deficiency was not significantly greater in those who manifested atopic disease during the study period than in those who did not, but the levels were significantly lower at 4 months.

Aging↗
PubMed1984

Effects of body temperature on ventilation, blood gases and acid-base balance in exercising fowl.

In order to determine the influence of hyperthermia on respiratory, blood gas and acid-base changes in exercising birds, we exercised domestic fowl on a treadmill at ambient temperatures of 5, 20, 30 and 35 degrees C for 10 min at graded running speeds up to 4.3 km.h-1. Ventilation and gas exchange were measured continuously and arterial blood gases, pH and the concentration of lactic acid in arterial blood were measured in samples taken during the last minute of each run. During exercise at 5 degrees C rectal temperature did not change significantly from rest (isothermic condition) and there was no sign of thermal influence on respiratory pattern, such as was observed at higher ambient temperatures. At any given running speed, increased ambient temperature caused increased ventilation by an increase in respiratory frequency (f) together with a decrease in tidal volume (VT). Under isothermic conditions, at low running speeds, birds maintained an isocapnic hyperpnoea: arterial PCO2, PO2 and pH and oxygen extraction were unchanged. However at higher speeds (ca. greater than 2.5 km.h-1) some hyperventilation occurred with subsequent falls in arterial PCO2 and oxygen extraction. Arterial pH also fell significantly (P less than 0.01). During hyperthermic exercise, oxygen extraction, arterial PCO2 and bicarbonate concentration all fell significantly (P less than 0.01) and progressively with increasing work load, and birds hyperventilated at all running speeds. This produced a significant arterial hypocapnia and alkalosis at the lower speeds (P less than 0.05) but this was replaced by a hypocapnic metabolic acidosis at the higher running speeds. Blood lactate concentration rose steeply at speeds above ca. 2.5 km.h-1 but arterial pH fell by only 0.1 units or less partly as a result of buffering by blood bicarbonate. It is concluded that both hyperthermia and lactacidosis are causes of hyperventilation and arterial hypocapnia during heavy running exercise in birds. However, ventilatory adjustments similar to those observed in resting hyperthermic birds, viz. increased f and reduced VT prevent severe arterial hypocapnia from occurring in hyperthermic exercising birds.

Acid-Base Equilibrium↗
PubMed1984

Vagal control of respiratory pattern during hyperpnea in domestic fowl.

Minute volume, tidal volume, and respiratory frequency were measured during hyperpnea induced by exercise, increased body temperature, and CO2 inhalation. Ventilatory characteristics were compared before and after the vagus nerve had been blocked. In normal birds exercise produced increases in both tidal volume and respiratory frequency; hyperthermia produced a typical thermal polypnea consisting of greatly increased respiratory frequency and reduced tidal volume; CO2 inhalation produced increases in tidal volume and respiratory frequency when the birds were euthermic but a slowing of respiratory rate when the birds were hyperthermic. After vagal block these pronounced differences in the pattern of ventilatory response to the various respiratory stimuli were abolished. Instead there was a uniform ventilatory response to all three stimuli consisting mainly of increases in tidal volume combined with small increases in respiratory frequency. It is concluded that in the normal animal control of the varied pattern of ventilatory response to different respiratory stimuli is dependent on vagal fiber activity.

Animals↗
PubMed1983

Effects of PCO2 on respiratory pattern during thermal and exercise hyperventilation in domestic fowl.

The relationship between respiratory pattern and arterial PCO2 was investigated during hyperventilation induced by graded exercise and hyperthermia. Treadmill exercise was performed both in isothermic and hyperthermic conditions. Isothermic exercise was induced by spraying the birds with water before exercise at environmental temperatures of 18 +/- 2 degrees C. Hyperthermic exercise was performed in unsprayed birds at temperatures of 18 +/- 2 degrees C and 30 +/- 2 degrees C. During isothermic exercise there was no significant change in arterial PCO2 at moderate work loads and only a small drop in PCO2 at the heaviest work loads; ventilation was increased by coupled increases in tidal volume and respiratory frequency. During exercise in unsprayed birds rectal temperature rose progressively and arterial PCO2 fell progressively with work load. At each work load ventilation was higher and breathing was more rapid and shallow than during isothermic exercise. These effects were more pronounced during exercise at 30 +/- 2 degrees C than at 18 +/- 2 degrees C. When normal PCO2 was maintained during hyperthermic exercise, as a result of the administration of CO2-enriched air, polypnea was suppressed and the tidal volume-respiratory frequency relationship became identical to that observed during graded isothermic exercise. Maintenance of normal PCO2 in resting birds subjected to a gradual increase in environmental temperature also resulted in changes in respiratory pattern identical to those obtained during eucapnic exercise. It is concluded that, provided arterial PCO2 is held constant, the pattern of breathing is the same for hyperventilation induced by exercise or by body temperature increases.

Animals↗
PubMed1983

Respiratory and blood gas responses in exercising birds.

The effects of exercise in birds on changes in body temperature, ventilation, blood gases and air-sac gases are reviewed. Except in the case of isothermic exercise below the anaerobic threshold, birds hyperventilate during exercise. Exercise hyperventilation is greater at higher exercise intensities and at higher environmental temperatures. The domestic fowl appears to be a suitable model for the study of physiological responses to exercise in running birds. A prior period of training is necessary to accustom the birds to laboratory procedures. The possible neural and/or humoral mechanisms controlling exercise hyperpnea are listed. Intrapulmonary hypocapnia seems to exclude the possibility that lung chemoreceptors are responsible for the hyperpnea during exercise, but these receptors probably play a predominant role in the determination of ventilatory pattern.

Animals↗
PubMed1983

Ventilation, gaseous exchange and air sac gases during moderate thermal panting in domestic fowl.

Gaseous exchange, ventilatory pattern and gas levels within the interclavicular and abdominal air sacs of domestic fowl were monitored before, during and after periods of moderate hyperthermic panting. O2 consumption (VO2) remained virtually unaltered and CO2 production (VCO2) increased slightly during panting as compared to normal respiration. Resting VO2 was 12.2 ml X kg-1 X min-1. Resting (eupneic) PO2 and PCO2 of the interclavicular and abdominal air sacs were 100.1 and 38.5 torr, and 125.2 and 16.4 torr respectively. During panting the partial pressure of the abdominal air sac Pabs, O2 and Pabs, CO2 fell and rose to extreme values of 109 and 29.8 torr respectively. Simultaneously the partial pressure of the interclavicular air sac Pics, O2 and Pics, CO2 changed by smaller amounts to 107.5 and 32.3 torr respectively. Ventilatory pattern during thermal panting was characterized by rapid, shallow movements which were interrupted at regular intervals by short sequences of slower, deeper breaths. During these intermittent periods of eupneic breathing gas levels returned towards normal and these alterations were reflected in transient variations in VO2 and VCO2 about their mean values. Changes in gas levels within the lung-air sac system are discussed in connexion with the peripheral control of ventilation during panting.

Acid-Base Equilibrium↗
PubMed1982

Effects of temperature on the ventilatory response to inspired CO2 in unanaesthetized domestic fowl.

The influence of raised environmental temperature on the respiratory response to CO2 in awake, spontaneously breathing domestic fowl was investigated. In terms of their effects on ventilation VE temperature and CO2 were additive and non-interactive, VE being approximately 1900 ml . min-1 greater at 33 +/- 1 degree C compared to 18 +/- 1 degree C, regardless of inspired CO2 partial pressure PICO2. Temperature had no effect on the slope of the relationship between VE and both arterial and clavicular air sac PCO2. Blood and clavicular sac PCO2 were regulated within 2-3 Torr of normal at PICO2 levels below approximately 20 Torr as a result of hyperventilation but PCO2 regulation began to fail at higher PICO2. Hypercapnia induced increases in respiratory frequency f at normal temperatures but decreases in f at 33 +/- 1 degree C. There was little change in f at 25 +/- 1 degree C. The ventilatory increase in response to CO2 at 18 +/- 1 degree C and 25 +/- 1 degree C could be described by a linear relationship between VE and tidal volume VT. However, respiration departed from this pattern at temperatures above the panting threshold (32-34 degrees C). These findings are discussed in the context of central and peripheral mechanisms which may be involved in the control of rate and depth of breathing.

Animals↗
PubMed1982

The effects of physical exercise on metabolic rate and dietary-induced thermogenesis.

1. The energy metabolism of ad lib.-fed adult male Wistar rats receiving daily running exercise (0.9 km/d; 8 degrees incline) on a motor-driven treadmill, over a period of 56 d, was compared with that of sedentary ad lib.-fed rats and sedentary restricted-fed rats of similar body-weight (approximately 420 g). 2. The metabolizable energy of the diet (Oxoid 41 B) was 11.44 +/- 0.05 kJ/g. This value was not affected by restricted feeding (70% ad lib.), exercise training or exercise itself. 3. Exercise-trained rats ate 5% more food than the sedentary ad lib.-fed rats but their equilibrium body-weight was 60 g lower than that of the latter group. 4. Resting metabolic rate, measured over 22 h in a respiration chamber was increased by 10% in exercise-trained animals. 5. Feeding increased energy expenditure (dietary-induced thermogenesis) and this effect was potentiated by performance of an exercise task. 6. Exercise-trained rats exhibited anticipatory rises in energy expenditure (approximately 40%) when placed on a stationary treadmill. 7. Treadmill work increased energy expenditure by a factor of 1.9-2.4. 8. The energy cost of the exercise, determined by respiration calorimetry was 66-80 J/g per km. These energy costs did not account for all the differences observed in food energy consumption of exercise-trained and sedentary rats of equal body-weight. 9. It is concluded that regular physical exercise increases energy expenditure by factors additional to the energy requirement directly related to the physical work. These factors include an increased resting metabolic rate in exercise-trained rats, increased dietary thermogenesis induced by exercise and anticipatory increases in energy metabolism during the period preceding exercise.

Animals↗
PubMed1982

Ontogeny of the secretory immune system in man.

Immunoglobulin and albumin concentrations and Escherichia coli antibody levels were determined in a prospective study of saliva taken from 63 healthy infants during the first year of life. Albumin and IgG were present in high concentrations at birth (57 +/- 6 and 35 +/- 8 mg/l respectively) and decreased in parallel to low values at two months of age. IgA was detected by three weeks of age. The IgA concentration fluctuated until six months of age, after which constant values were observed (14 +/- 3 mg/l). Low levels of salivary IgM (2.4 +/- 1.2 mg/l) were demonstrated in 37% of infants at four weeks of age. No E. coli antibody was detected. There was no significant difference between breast-fed and formula-fed infants. These findings suggest: (i) that mucosal membrane permeability is not restricted to the gut; (ii) that changes in mucosal permeability are non specific and not restricted to the uptake of specific food protein or ingestion of maternal milk; (iii) maternal IgG may contribute to mucosal defence in the neonate; (iv) fluctuations in the concentration of IgA may reflect a balance between intense antigenic stimulation in the gut in the first weeks of life and immune regulatory mechanisms and (v) ingestion of maternal milk does not modify the pattern of ontogeny.

Albumins↗
PubMed1982

Control of ventilation in running birds: effects of hypoxia, hyperoxia, and CO2.

Minute volume (V), tidal volume (VT), respiratory frequency (f), venous lactate, and clavicular air sac gas composition were measured in domestic fowl at rest and during exercise, breathing hypoxic, hyperoxic, or hypercapnic gas. Hyperoxia produced no significant change in ventilation, CO2 inhalation produced increases in V and VT, but the changes in f appeared to be related to the stage of exercise at which CO2 was administered. The sensitivity of the hypercapnic response was similar in resting and exercising birds. Compared with the effects of CO2, hypoxia elicited only a weak ventilatory response in rest and exercise conditions despite severe tissue anaerobiosis.

Animals↗
PubMed1981

Respiration in exercising fowl. I. Oxygen consumption, respiratory rate and respired gases.

1. Oxygen consumption, respiratory frequency, and the PO2 of expiratory and interclavicular air sac gases were continuously monitored in six female domestic fowl trained to exercise on a treadmill for 10 min periods at normal or elevated air temperatures. 2. At normal temperatures (20 +/- 2 degrees C) the cost of locomotion rose from 0.46 ml O2 kg-1 m-1 at 0-3 km h-1 to 0.77 ml O2 kg-1 m-1 at the maximum speed of 4.3 km h-1. At 32 +/- 2 degrees C, Vo2 increased by as much as 20% compared to normal temperatures. 3. Hyperventilation occurred at all speeds and at both normal and elevated temperatures. End-tidal and interclavicular PO2 increased, in a parallel manner with speed, the latter remaining consistently 6-7 Torr less than the former both at rest and during exercise.

Animals↗
PubMed1981

Respiration in exercising fowl. II. Respiratory water loss and heat balance.

1. Respiratory water loss and rectal temperature were measured in domestic fowl running for 10 min on a treadmill at speeds of 1.24-4.3 km h-1 in air temperatures of 20 +/- 2 degrees C or 32 +/- 2 degrees C. 2. At given speeds the water loss at 32 +/- 2 degrees C was approximately twice that at 20 +/- 2 degrees C and the end-exercise rectal temperature was 0.5-0.8 degrees C higher. 3. At 20 +/- 2 degrees C, respiratory evaporation accounted for 10-12% of the total metabolic energy used at all speeds. At 32 +/- 2 degrees C, the fractional respiratory heat loss fell from 26.5% at 1.24 km h-1 to 17% at 3.6 km h-1. The fraction of the total metabolic energy stored as body heat rose progressively with air temperature.

Animals↗