Biomedical subjects

W D Reid

Publications and source records attributed to W D Reid.

At least 37 records · Page 2Linked to original sources

PubMed1995

Pulmonary mechanics of hibernating squirrels (Spermophilus lateralis).

In this study we examined the effects of hibernation on several aspects of pulmonary mechanics in golden mantled ground squirrels. Measurements were made on anesthetized animals that were active in late fall (FA, n = 7), maintained at 23 degrees C and normal photoperiod in mid-winter (WA, n = 0) and hibernating at 5 degrees C in mid-winter (H, n = 8). Compared with FA animals, WA animals showed an increase in inspiratory reserve volume (IRV) and in inspiratory, vital and total lung capacities (IC, VC, and TLC). Hibernating animals exhibited further increases in IRV, IC, VC and TLC, an elevated residual volume, and virtual elimination of the expiratory reserve volume. There was also a decrease in specific lung compliance and a sharp knee in the lower portion of the quasi-static volume-pressure curve. There was a significant increase in the elastic work required to ventilate the hibernating animals compared with FA animals. The data suggest that, despite an increase in compliance at TLC, there is decreased compliance at low volumes, gas trapping at functional residual capacity, and an increase in the work required to breathe in hibernating animals.

Animals↗

PubMed1995

Characteristics of diaphragm muscle fibre types in hibernating squirrels.

Muscle samples from the diaphragms of 7 full-awake (FA), 10 winter-awake (WA), and 8 hibernating (H) squirrels (Spermophilus lateralis) were quick frozen, sectioned and processed for NADH-TR reaction end-product and myofibrillar-ATPase. Both WA and H squirrels showed small increases in diaphragm weight, reductions in body weight, and hence, significant increases in the diaphragm weight to body weight ratio compared to FA squirrels. They also showed increases in muscle fibre type cross-sectional areas and in the oxidative capacity of type 2b fibres as well as a reduction in capillary density. Furthermore, there also was an increase in the proportion of type 2b fibres in the diaphragm of the H squirrels. Thus, despite the dramatically reduced ventilation associated with hibernation, H squirrels exhibited (1) hypertrophy of the diaphragm which may represent an adaptive response that enables them to work against a stiffer chest wall, and (2) an increased oxidative capacity which enables them to fuel this with fat.

Animals↗

PubMed1995

Considerations when testing and training the respiratory muscles.

The purpose of this review is to describe the muscles of respiration, mechanisms that lead to their dysfunction, and unique features of the respiratory muscles that should be considered when designing testing and training protocols for patients with respiratory compromise. The diaphragm's unique shape is an important determinant of its function. Respiratory pathophysiology combined with systemic abnormalities may result in inspiratory muscle weakness, fatigue, and injury. The specificity of training principle, as it applies to respiratory muscle training in patients with respiratory compromise, will be described. Precautions related to this type of training will also be outlined. In conclusion, a better understanding of the mechanisms contributing to inspiratory muscle dysfunction will assist physical therapists in designing the most appropriate training programs. This article, along with the other articles in this focus on respiratory muscle training, will provide therapists with scientifically based guidelines for rehabilitation of patients with impaired respiratory muscle function.

Breathing Exercises↗

PubMed1995

Respiratory muscle training for patients with chronic obstructive pulmonary disease.

The purpose of this article is to describe respiratory muscle training techniques and the effectiveness of this training in patients with chronic obstructive pulmonary disease (COPD). The respiratory muscles can be strengthened, but the benefit of stronger respiratory muscles in patients with COPD is not clear. Maximal sustained voluntary ventilation, inspiratory resistive breathing, and threshold loading are the three most commonly used techniques for improving the endurance of the inspiratory muscles in patients with COPD. Recent studies using inspiratory resistive breathing with targeted devices or threshold trainers have shown more consistent increases in inspiratory muscle function and exercise tolerance than studies using other techniques. Endurance exercise involving the extremities improves inspiratory muscle endurance in younger individuals with cystic fibrosis but not in older persons with COPD. Recommendations are outlined regarding the techniques to use for respiratory muscle training and which patient populations may benefit from these techniques.

Breathing Exercises↗

PubMed1995

Delayed muscle soreness. The inflammatory response to muscle injury and its clinical implications.

Delayed onset muscle soreness (DOMS) is a sensation of discomfort that occurs 1 to 2 days after exercise. The soreness has been reported to be most evident at the muscle/tendon junction initially, and then spreading throughout the muscle. The muscle activity which causes the most soreness and injury to the muscle is eccentric activity. The injury to the muscle has been well described but the mechanism underlying the injury is not fully understood. Some recent studies have focused on the role of the cytoskeleton and its contribution to the sarcomere injury. Although little has been confirmed regarding the mechanisms involved in the production of delayed muscle soreness, it has been suggested that the soreness may occur as a result of mechanical factors or it may be biochemical in nature. To date, there appears to be no relationship between the development of soreness and the loss of muscle strength, in that the timing of the two events is different. Loss of muscle force has been observed immediately after the exercise. However, by collecting data at more frequent intervals a second loss of force has been reported in mice 1 to 3 days post-exercise. Future studies with humans may find this second loss of force to be related to DOMS. The role of inflammation during exercise-induced muscle injury has not been clearly defined. It is possible that the inflammatory response may be responsible for initiating, amplifying, and/or resolving skeletal muscle injury. Evidence from the literature of the involvement of cytokines, complement, neutrophils, monocytes and macrophages in the acute phase response are presented in this review. Clinically, DOMS is a common but self-limiting condition that usually requires no treatment. Most exercise enthusiasts are familiar with its symptoms. However, where a muscle has been immobilised or debilitated, it is not known how that muscle will respond to exercise, especially eccentric activity.

Cytokines↗

PubMed1994

Regional and fibre type glycogen utilization patterns in the hamster diaphragm following swimming.

The purpose of this study was to determine the regional and myofibrillar ATPase (M-ATPase) fibre type glycogen utilization patterns in response to increased ventilation induced by pre-exhaustive (Pre-Exh) and exhaustive (Exh) durations of swimming. Twenty-eight hamsters were studied: six controls (Con), 11 Pre-Exh (swam 82 min), 11 Exh (swam to exhaustion). We examined the optical density of PAS-stained fibres from the different regions of the diaphragm as a measure of glycogen remaining after the exercise or control period. The optical densities of PAS-stained fibres in most M-ATPase fibre types and diaphragmatic regions for the Pre-Exh and Exh groups was less than those in the Con hamsters except for the optical densities of all the M-ATPase fibre types in the sternal region. The optical densities of PAS-stained fibres in different regions and M-ATPase fibre types did not differ in the Exh and Pre-Exh groups. This data indicates that significant glycogen utilization occurred in all three M-ATPase fibre types in the costal, and both the thoracic and abdominal surface of the crural diaphragm in hamsters following pre-exhaustive and exhaustive durations of swimming. Glycogen utilization was greater in type 1 fibres of the thoracic surface of the crural region than in the type 1 fibres of the sternal region of the Pre-Exh group. Further, significant utilization of glycogen did not occur in any of the three M-ATPase fibre types of the sternal region of the diaphragm following prolonged durations of swimming. It would appear that glycogen is an important substrate in the hamster diaphragm during swimming.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine Triphosphatases↗

PubMed1994

Diaphragm injury and myofibrillar structure induced by resistive loading.

The purpose of this study was to determine whether ventilatory failure is associated with muscle fiber damage and myofibrillar protein alterations. Ventilatory failure was induced by tightening a polyvinyl band around the trachea of hamsters (TB; n = 14) for 6 days, which resulted in severe respiratory acidosis (PCO2: 97.9 +/- 29.6 vs. 51.6 +/- 19.6 Torr; pH: 7.16 vs. 7.35), hypoxemia (PO2: 42.8 +/- 16.8 vs. 65.9 +/- 25.8 Torr), and increased pulmonary resistance (1.89 +/- 1.61 vs. 0.29 +/- 0.27 cmH2O.ml-1 x min; P < 0.05). The point-counting technique of hematoxylin- and eosin-stained cross sections showed a higher area fraction of abnormal muscle and inflammatory cells in the costal [0.133 +/- (SE) 0.33 vs. 0.040 +/- 0.010] and crural regions (0.069 +/- 0.020 vs. 0.012 +/- 0.003) of the diaphragm in TB hamsters than in control hamsters. Electron micrographs revealed sarcomeric disruption and Z band streaming in the diaphragm of TB hamsters. Myofibrillar changes of the diaphragm associated with ventilatory failure were quantitative (i.e., a lower yield of purified myofibrils) but not qualitative (similar sodium dodecyl sulfate-polyacrylamide gel electrophoresis protein profiles); however, sulfhydryl group reactivities were reduced (P < 0.05). Proteolysis of purified myofibrils from the diaphragm digested with calpain showed faster degradation rates for tropomyosin and alpha-actinin but not for all proteins for the TB animals. Ventilatory failure induced by resistive loading was associated with diaphragm injury; some of this injury was linked to changes in myofibrillar complexes, specifically their susceptibility to calpain-mediated degradation.

Actinin↗

PubMed1993

Lumbar epidural anaesthesia for inguinal hernia repair in low birth weight infants.

In view of the complications of general, spinal, and caudal anaesthesia for inguinal hernia repair in high-risk neonates, an evaluation of lumbar epidural anaesthesia (LEA) was undertaken to assess its technical feasibility, effectiveness and incidence of complications. In 18 consecutive cases, gestational age 26 +/- 2.6 wk, birth weight 877 +/- 310 g, 16 (89%) had bronchopulmonary dysplasia and 12 (67%) were oxygen-dependent at the time of surgery. Using a standard loss of resistance technique and a 4.0 cm 20 G epidural needle, the epidural space was positively identified on the first attempt in 16 (89%), and on the second attempt in 2 patients (11%). Reflux of 0.9% saline used to identify the epidural space was blood tinged in two cases. Epidural analgesia was achieved in all cases with bupivacaine 0.25% with and without 1:200,000 epinephrine, 0.75 ml.kg-1 for the first two cases, and subsequently 1.0 ml.kg-1. In 15 patients (83%), good operating conditions were achieved with epidural analgesia alone. Inhalational anaesthesia supplementation was necessary in three cases (17%). In the first two patients, the level of analgesia (T8) was insufficient to control the response to traction on the hernial sac. In one infant, analgesic to T4, whose surgery was inadvertently delayed for four hours, inhalation anaesthesia was needed to control restlessness rather than pain. Ten infants were analgesic to T2, four to T4, two to T6 and two to T8. Intraoperative periodic breathing was seen in seven infants (39%), four with oxyhaemoglobin desaturation to 75%, and two to 85%. All responded to increased FIO2.(ABSTRACT TRUNCATED AT 250 WORDS)

Analgesia, Epidural↗

PubMed1993

Preampullary congenital duodenal obstruction in a father and son.

This is the report of an infant seen on June 25, 1960 with preampullary total duodenal obstruction caused by a combined annular pancreas and duodenal stenosis above the ampulla. A gastroduodenostomy was performed. In December 1989, he fathered a 1,700-g boy with preampullary duodenal atresia. A duodeno-duodenostomy was performed successfully by the same pediatric surgeon. Second-generation duodenal obstruction is rare; to our knowledge, there are no other cases.

Adult↗

PubMed1993

Circadian rhythm of glycogen in the hamster diaphragm.

The purpose of this study was to determine the diurnal fluctuation of glycogen stores for the whole hemidiaphragm and within a specific myofibrillar ATPase (M-ATPase) fibre type and diaphragmatic region. Fifty-six golden Syrian hamsters were randomly divided into six groups according to the time of sampling biopsies from the diaphragm: 03:00, 07:00, 11:00, 15:00, 19:00, and 23:00. The right hemidiaphragm was quick frozen and biochemically assayed for glycogen levels. Biopsies from the left hemidiaphragm of the same animal were cut from the anterior costal and crural regions, and stained with periodic acid--Schiff (PAS) and for M-ATPase. Optical density measures of PAS-stained fibres were determined to quantitate glycogen in different M-ATPase fibre types and diaphragmatic regions. Biochemical assay of the entire hemidiaphragm showed slightly greater glycogen content of biopsies taken at 11:00 and 15:00 than at 03:00, 19:00, and 23:00 (range of differences: 6.4-10.0%). However, glycogen levels within a specific M-ATPase fibre type and diaphragm region were not different in biopsies sampled at different times. Because the hamster has a small diurnal variation of glycogen in the diaphragm, which is similar to the small diurnal variation of glycogen in human skeletal muscle, this species may be a good animal model for metabolic studies of the diaphragm that could be affected by diurnal glycogen variability.

Adenosine Triphosphatases↗

PubMed1992

Ventilatory failure induced by tracheal banding in the hamster.

Previous animal models of hypercapnic ventilatory failure are limited in that the resistive load has only been applied acutely and often in anesthetized animals. We therefore developed a chronic animal model of hypercapnic ventilatory failure by increasing airway resistance via tracheal banding over several days. To test the efficacy of this model, we compared arterial blood gases, pulmonary function, and internal area of the trachea 6 days after the banding or sham procedure in 20 hamsters. Six days later, banded animals had an increased airway resistance as indicated by a 66% reduction in internal cross-sectional area of the trachea and a 6.5-fold increase in pulmonary resistance compared with control hamsters. The increased airway resistance resulted in a severe respiratory acidosis and hypoxemia in the awake banded hamsters. Banded hamsters were also hyperinflated. This animal model will be useful for investigating the various mechanisms that contribute to hypercapnic ventilatory failure and interventions that may promote recovery.

Acidosis, Respiratory↗

PubMed1992

Fiber type and regional differences in oxidative capacity and glycogen content in the hamster diaphragm.

The purpose of this study was to define variability of the oxidative capacity and glycogen content between different fiber types and regions of the hamster diaphragm. Using histochemical and microphotometric techniques, the oxidative capacity (identified by nicotinamide-adenine dinucleotide tetrazolium reductase reaction end product) and glycogen levels (identified by the periodic acid-Schiff stain test) were examined in three myofibrillar ATPase (M-ATPase) fiber types and four diaphragmatic regions: sternal, anterior costal, thoracic surface of the crural (thor/crur), and abdominal surface of the crural (abd/crur). Most regional differences were found between the crus and the rest of the diaphragm. There were no differences in the oxidative capacity between diaphragmatic regions in the types 1 and 2a fibers, but the type 2b fibers in the thor/crur region had the greatest oxidative capacity and the 2b fiber in the sternal region had the lowest oxidative capacity. There were differences in glycogen content between diaphragmatic regions for all of the three M-ATPase fiber types. Variability in oxidative capacity between fiber types was demonstrated in all regions except the thor/crur region. Variation in glycogen content between fiber types was only demonstrated in the two surfaces of the crus. The type 2b fiber demonstrated the most differences from types 1 and 2a fibers in oxidative capacity and glycogen content in the different diaphragmatic regions, whereas the types 1 and 2a fibers demonstrated few differences from each other in these features across the different diaphragmatic regions.(ABSTRACT TRUNCATED AT 250 WORDS)

Aminosalicylic Acid↗

PubMed1990

A digital technique for stimulus artifact reduction.

A method of recovering compound muscle action potentials which are overwhelm by a stimulus artifact is presented. In the specific example reported, such action potentials were recorded from the hamster diaphragm using an apposing platinum electrode for both stimulation and recording. To recover the artifact-free action potential, a combination of digital data acquisition and simple signal processing was employed. The recording of a stimulus artifact from a sub-threshold stimulus was used to subtract the artifact component from subsequent recordings and thus faithfully reveal the action potentials. The technique should find application in other preparations.

Action Potentials↗

PubMed1990

Respiratory muscle fiber morphometry. Correlation with pulmonary function and nutrition.

To examine the relationship between nutrition, pulmonary function, respiratory muscle strength, and respiratory muscle morphometry, we compared physiologic data and muscle morphometry obtained from internal intercostal, external intercostal, and latissimus dorsi muscle biopsies in 68 patients who were having a thoracotomy. We stained the biopsies for myosin ATPase and measured the proportions and diameters of the type 1 and type 2 fibers. There were more qualitative changes in the external intercostal muscles than in the other two, and some of these changes related to the incidence of malignancy. There were more type 1 fibers in the external intercostal (64 +/- 10 percent) and internal intercostal muscles (59 +/- 12 percent) than in the latissimus dorsi (44 +/- 13 percent) (p less than 0.005). The mean diameter of the type 2 fibers in the external intercostal muscles was less (44 mu +/- 7 mu) than the diameter in the latissimus dorsi (51 mu +/- 9 mu) and the internal intercostal muscles (52 mu +/- 8 mu) (p less than 0.01). The diameters of both fiber types were greater in men than in women. There was no significant relationship between measures of pulmonary function or respiratory muscle strength and muscle fiber proportions and diameters. There were significant correlations between the percentage of ideal body weight and type 1 and type 2 fiber diameters. We conclude that sex and nutrition influence respiratory muscle morphometry.

Biopsy↗

PubMed1989

Proportions and sizes of muscle fiber types in the hamster diaphragm.

This study demonstrated that there was interanimal and interregional variability of proportions and sizes of the muscle fiber types in the hamster diaphragm. Muscle fiber type proportions and sizes were determined for each side (right, left), surface (abdominal, thoracic), and region (sternal, anterior costal, posterior costal, crural) in six hamsters. There was marked regional and surface-to-surface variability and some interanimal variability in proportions and sizes of fiber type within the hamster diaphragm. The sternal and costal regions were relatively homogeneous. However, there were differences in both proportions and sizes of fiber types between the thoracic surface of the crural region and the abdominal surface of the crural region. These two surfaces of the crural region differed from the rest of the diaphragm. For muscle fiber type proportions, type 2a fibers demonstrated the most interanimal variability. Muscle fiber size varied little between animals.

Animals↗

PubMed1989

Diaphragmatic plate electrode stimulation of the hamster diaphragm.

We developed a new technique of diaphragmatic stimulation by apposing plate electrodes directly against the diaphragm (DPS) in adult Golden Syrian hamsters. The electrophysiological and the mechanical responses to DPS were compared with those with phrenic nerve stimulation. In four animals, evaluation of the electromyogram before and after curare demonstrated that plate electrode stimulation occurred via the phrenic nerve filaments. In four animals, similar transdiaphragmatic pressure was produced at maximal current with DPS and phrenic nerve stimulation. Using DPS increasing current beyond a certain level resulted in recruitment of muscles besides the diaphragm. In six animals, an external abdominal pressure of 15 cmH2O produced maximal transdiaphragmatic pressure, suggesting that the diaphragm was contracting near optimal position with this external abdominal pressure. In another four animals the twitch and pressure-frequency characteristics with the use of DPS were found to be reproducible over a 2-h period. We conclude that DPS is an effective method of diaphragmatic stimulation and should prove to be a valuable technique to study the diaphragm in long-term studies of small rodents.

Action Potentials↗

PubMed1989

An effective combination of anaesthetics for 6-h experimentation in the golden Syrian hamster.

The anaesthetics described for use in hamsters to date are suitable for the performance of short-term experimentation. However, an anaesthetic regimen was required which would provide a stable preparation for 6 h and hence, a suitable combination was developed. In the first set of experiments, the effect of anaesthetics (chloralose, urethane, and pentobarbital) were examined alone and in combination on arterial blood measurements. In the second set of experiments the effect of the combination of anaesthetics on arterial blood measurements and minute ventilation was examined for up to 6 h. Chloralose, urethane and pentobarbital when used alone in the hamster were considered inadequate for our needs. Chloralose did not produce adequate surgical anaesthesia whereas urethane and pentobarbital resulted in marked respiratory depression. Urethane also produced a trend towards metabolic acidosis. In contrast, the combination of agents resulted in surgical anaesthesia and the arterial blood measurements were adequate. Further, the use of the combination of anaesthetics in hamsters resulted in a stable preparation where arterial blood measurements and minute ventilation were maintained in a good range for up to 6 h. The combination of chloralose, urethane and sodium pentobarbital in hamsters should prove useful in long-term non-recovery experimentation which requires early surgical intervention, minimal respiratory depression and an even depth of anaesthesia.

Anesthesia↗

PubMed1988

Cigarette smoke inhalation patterns and bronchial reactivity.

The manner in which a cigarette is smoked varies considerably between individuals and may be an important determinant of the altered bronchial reactivity observed in cigarette smokers. Twenty smokers were examined to determine the relationship between cigarette smoke inhalation patterns and bronchial reactivity. Inhalation patterns were measured non-invasively with a respiratory inductive plethysmograph and these were related to the provocative concentration of histamine that caused a 20% fall in FEV1 (PC20) and to the cough threshold for inhaled citric acid. Histamine PC20 values were inversely correlated with depth and rate of inhalation. Cough threshold was inversely correlated with greater cigarette consumption and with depth of inhalation.

Adult↗