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Biomedical subjects

C A Roberts

Publications and source records attributed to C A Roberts.

At least 37 records · Page 2Linked to original sources
PubMed2000

Respiratory responses of mature horses to intravenous lobeline bolus.

The respiratory stimulant lobeline has been used in equine clinical practice to increase inspiratory and expiratory airflow rates at rest in order to facilitate investigation of both lower and upper airway function. Some of the responses to lobeline in the pony have been reported, but the detailed time course, effect of dose, possible side effects and reproducibility associated with lobeline administration have not been described in the horse. Respiratory airflow rates and oesophageal pressure were measured with a Fleisch No. 5 pneumotachometer and lightweight facemask and a microtip pressure transducer catheter, respectively. The output of the Fleisch pneumotachometer was calibrated for flow rates up to +/- 70 l/s. Seven mature horses with no clinical signs of respiratory disease were studied. Investigations were conducted to determine: (1) the responses to different doses of lobeline (0.15, 0.20, 0.25 and 0.30 mg/kg bwt) as a rapid i.v. bolus (6 horses); (2) arterial blood gases during and after lobeline administration (0.20 mg/kg bwt; 3 horses); and (3) the reproducibility of lobeline-stimulated hyperpnoea (5 horses; 2 doses of 0.20 mg/kg bwt lobeline, 15 min apart). All horses tolerated the lobeline-stimulated hyperpnoea well, although one always coughed or snorted at the onset. Mild tremor was noted following the highest dose in several horses. Apnoea of approximately 40 s was common after the hyperpnoea. Both tidal volume (VT) and frequency (fR) increased with lobeline dose. During peak hyperpnoea at a dose of 0.30 mg/kg bwt, peak inspired flow rate (PIF), peak expired flow rate (PEF) and minute ventilation (VE) were mean +/- s.e. 41+/-5 l/s, 61+/-10 l/s and 920+/-99 l/min, respectively. The hyperpnoea also caused marked changes in arterial PaO2, PaCO2 and pHa at 90 s after lobeline (0.20 mg/kg bwt) administration (mean +/- s.e. 146.0+/-6.9 mmHg, 20.6+/-0.8 mmHg and 7.707+/-0.020, respectively) compared to at rest (mean +/- s.e. 104.0+/-4.0 mmHg, 50.6+/-2.8 mmHg and 7.432+/-0.012). Dynamic lung compliance (Cdyn) was unaltered by lobeline administration. The lobeline-induced hyperpnoea was highly reproducible, with no significant difference in any of the parameters during 2 stimulations 15 min apart. Lobeline induced highly reproducible responses without any apparent adverse effects and may be useful in the investigation of pulmonary function in healthy horses and those with airway disease.

Animals↗
PubMed2000

Is infection control in residential homes neglected?

We investigated the potential for cross infection during the cleaning of commodes in residential homes in one health authority in order to investigate why residential institutions are the commonest setting for outbreaks of infectious intestinal disease. Most homes used commodes, but half lacked a designated sluice area for cleaning them after use and in half soiled commodes were cleaned in bathroom or toilet washbasins, baths, showers, or toilet pans, creating a risk of cross infection.

Cross Infection↗
PubMed1999

Sleep-related changes in the human 'neuromuscular' ventilatory response to hypoxia.

The ventilatory responses to hypercapnia and hypoxia are reduced during sleep compared to wakefulness. However, sleep-related increases in upper airways' resistance could reduce these ventilatory responses independently of any change in the neural output to the respiratory pump muscles. It is therefore possible that respiratory chemosensitivity, per se, is unchanged by sleep. To investigate this, four healthy male subjects were mechanically ventilated to abolish spontaneous respiratory muscle activity. The response to transient isocapnic hypoxia was quantified from the magnitude of the electromyographic activity induced in the diaphragm and from the associated reduction in peak inspiratory pressure; these indicies of respiratory motor output will not be affected by any sleep-related changes in upper airways' resistance. In all individuals, the responses to hypoxia were markedly attenuated during sleep compared to wakefulness. These observations, assessing the 'neuromuscular' ventilatory response, are consistent with a sleep-related reduction in respiratory chemosensitivity that is independent of any changes that may be due to increases in upper airways' resistance.

Adult↗
PubMed1999

Fracture trauma in a medieval British farming village.

Farming is among the three most hazardous occupations in modern society and perhaps also held a similar position during the medieval period. The goal of this study was to determine if there is a significant difference in frequencies and patterns of longbone fracture trauma observed between rural and urban activity bases that distinguish farming as a particularly dangerous occupation during the medieval period. The longbones of 170 individuals excavated from Raunds, a rural medieval British site (10th-12th centuries AD) were examined for fractures and compared to data collected from four contemporary British medieval sites, one rural and three urban. The fracture frequency for the Raunds individuals (19.4%) was significantly different from the urban sites (4.7-5.5%). Female fractures were characterized by injury to the forearm, while the males were predisposed to diverse fracture locations. Clinical research provided a source of documented farm-related trauma from North America and Europe where the crops and animals raised, the manual chores performed, and the equipment used in traditional or small-scale farms have changed little in form or function since the medieval period. Nonmechanized causes of injury contribute to approximately 40% of all modern farm-related injuries and are attributed to falls from lofts and ladders, animal assaults and bites, and falls from moving vehicles. These hazardous situations were also present in the medieval period and may explain some of the fracture trauma from the rural sites. A high fracture frequency for both medieval males and females is significantly associated with farming subsistence when compared to craft-orientated urban dwellers.

Adult↗
PubMed1999

Physiological responses of horses to a treadmill simulated speed and endurance test in high heat and humidity before and after humid heat acclimation.

To investigate whether horses were able to acclimate to conditions of high temperature and humidity, 5 horses of different breeds were trained for 80 min on 15 consecutive days on a treadmill at 30 degrees C and 80%RH. Training consisted of a combination of long duration low-intensity exercise, medium duration medium intensity exercise and short duration high intensity exercise. Between training sessions the horses were maintained at 11+/-3 degrees C and 74+/-2%RH. Before (PRE-ACC) and after acclimation (POST-ACC) the horses undertook a simulated Competition Exercise Test (CET), designed to represent the Speed and Endurance Test of a 3-day event, at 30 degrees C/80%RH. Maximal oxygen uptake (VO2PEAK) was not changed following acclimation (PRE-ACC 141+/-8 ml/min/kg bwt vs. POST-ACC 145+/-9 ml/min/kg bwt [STPD], P>0.05). Following acclimation, 4 of the 5 horses were able to complete a significantly greater amount of Phase D in the CET (PRE-ACC 6.3+/-0.3 min vs. POST-ACC 7.3+/-0.3 min, P<0.05; target time = 8 min). Resting body temperatures (pulmonary artery [TPA], rectal [TREC] and tail-skin [TTSK] temperatures) were all significantly lower following acclimation. During exercise, metabolic heat production (M) and heat dissipation (HD), for the same exercise duration, were both significantly lower following acclimation (P<0.05), although heat storage (HS) was significantly higher (P<0.05). The higher heat storage following acclimation was associated with a lower TTSK for a given TPA and a decreased total fluid loss (% bodyweight, P<0.05). Plasma volume was not changed following acclimation. The relationship of sweating rate (SR) to TPA or TTSK on either the neck or the gluteal region was not significantly altered by acclimation, although the onset of sweating occurred at a lower TPA or TTSK following acclimation (P<0.05). The horses in the present study showed a number of physiological adaptations to a period of 15 days of exposure to high heat and humidity consistent with a humid heat acclimation response. These changes were mostly similar to those reported to occur in man and other species and were consistent with thermal acclimation and an increased thermotolerance, leading to an improved exercise tolerance. It is concluded that a 15 day period of acclimation is beneficial for horses from cooler and or drier climates, that have to compete in hot humid conditions and that this may redress, to some extent, the decrement in exercise tolerance seen in nonacclimated horses and reduce the risk of heat related disorders, such as heat exhaustion.

Acid-Base Equilibrium↗
PubMed1999

The effects of training on ventilation and blood gases in exercising thoroughbreds.

The effects of training on ventilation and blood gases during exercise were investigated in 6 clinically normal, detrained Thoroughbred horses. They underwent a 16 week training programme similar to the type frequently used for Thoroughbred racehorses in Great Britain. Standardized treadmill exercise tests (2 min canter at 8 and 10 m/s C8 and C10[ and 2 min gallop at 12 m/s [G12], on a level surface) were performed prior to and after 16 weeks of training. Respiratory flow rates were measured using ultrasound flow transducers. Blood samples were drawn from a transverse facial artery and the right atrium. Minute ventilation, respiratory frequency and tidal volume were not significantly altered by training. Peak inspiratory flow rate was lower following training at 8 and 10 m/s, but not at 12 m/s. Arterial oxygen tension was decreased during trot and canter following training. Blood lactate concentration post G12 decreased following training (10.5 +/- 2.2 mmol/l vs. 7.7 +/- 2.2 mmol/l; P < 0.05). The increase in the degree of exercise-induced arterial hypoxaemia following training may reflect a lack of pulmonary adaptation to training in the face of improved cardiovascular and muscular function.

Animals↗
PubMed1999

Effect of exercise on concentrations of immunoreactive endothelin in bronchoalveolar lavage fluid of normal horses and horses with chronic obstructive pulmonary disease.

Chronic obstructive pulmonary disease (COPD) represents a major cause of loss of performance in the horse. The role of endothelin (ET), a potent bronchoconstrictive and vasoactive peptide, is currently being investigated in asthma and other obstructive respiratory diseases in man. We have previously found elevated systemic and pulmonary endothelin levels in horses during exacerbation of COPD. In the present study, our aim was to examine possible variations in ET concentrations occurring during exercise in COPD horses. We compared the effects of intense treadmill exercise on the recovery of endothelin (ET) in the bronchoalveolar lavage fluid (BALF) as well as in arterial and venous blood, in a group of 5 healthy horses and a group of 5 COPD horses studied alternately in remission and while symptomatic. We also investigated the possible correlations between ET levels and pulmonary function tests during the study. While exercise did not affect the ET levels recovered in BALF among controls, it caused a significant increase (P = 0.02) among symptomatic COPD horses. During remission, wide variations of ET levels among horses, at rest and during exercise, made any significant interpretation difficult. No correlation could be found between exercise-induced changes in ET concentrations and pulmonary function tests or changes in arterial oxygen tension with exercise. We conclude that exercise appears to affect the release of ET by the airways in COPD horses, in contrast to healthy horses. It is still unclear, however, whether these differences relate to adjustments of lung function during exercise.

Animals↗
PubMed1999

Pre- and post exercise echocardiography in horses performing treadmill exercise in cool and hot/humid conditions.

We hypothesised that exercise in a hot and humid environment would affect echocardiographic indices of cardiac dimensions and function more than exercise in a cool environment. M-mode echocardiograms were obtained in 5 clinically normal horses before, and at 0, 10, 30 and 60 min after a treadmill exercise test. The test was performed in a controlled environment at 20 degrees C/40% relative humidity (RH) and again at 30 degrees C/80% RH. All the horses completed the exercise test in cool conditions, but only one horse completed the exercise test in the hot/humid environment. The relaxation time index (RTI) correlated significantly and inversely with heart rate (HR). Heart rate was increased and RTI was decreased immediately after exercise in cool conditions. HR recovery appeared to be prolonged following exercise in hot/humid conditions. Post exercise RTI was significantly decreased in hot/humid environment. In hot/humid conditions, the left ventricular internal dimensions measured in diastole and systole (LVIDd, LVIDs) were reduced following exercise and continued to fall throughout the 60 min after exercise. The left ventricular fractional shortening (FS%) was lower than resting levels immediately after exercise in hot/humid conditions. Significant decreases were found in LVIDs and LVIDd, which may reflect a reduction in preload arising from dehydration or re-distribution of blood throughout the recovery period following exercise in the hot/humid environment. It was concluded that echocardiography was a useful tool in assessing cardiac responses to exercise in different climates.

Aerobiosis↗
PubMed1999

Feasibility of scintigraphy in exercise-induced pulmonary haemorrhage detection and quantification: preliminary studies.

We hypothesised that scintigraphic imaging of the lungs following injection of 99mTc labelled red blood cells (99mTc-RBC) in the exercising horse might enable exercise-induced pulmonary haemorrhage (EIPH) quantification. Ideally, to favour detection of bleeding, circulating 99mTc-RBC not involved in the haemorrhage should be removed from the circulation quickly. Altering RBC during labelling to stimulate splenic uptake of 99mTc-RBC may encourage this. In order to investigate this hypothesis, 99mTc-RBC distribution was followed for 1 h in 2 groups of horses. Group 1 was injected i.v., at rest, with radioactive nondenatured RBC (99mTc-NDRBC); Group 2 received labelled RBC partly denatured by heating (99mTc-HDRBC). In Group 2, splenic uptake was higher at all times and radioactivity in the lung was proportionally higher and decreased less quickly than in Group 1. Hence, the time-consuming 99mTc-HDRBC labelling technique did not demonstrate any advantage over the easier 99mTc-NDRBC labelling procedure. Additionally, the feasibility of scintigraphic visualisation of a small amount of pulmonary bleeding was confirmed with the following trial: using an endoscope, a radioactive solution mimicking 50 ml of bleeding was deposited at the usual site of EIPH in a live horse. The radioactivity recorded in that area was compared to the one obtained in the same region in Group 1 and 2. The activity measured 20 min post endoscopy corresponded to 33% of the activity obtained in Group 1 vs. 8% in Group 2 at that timing. Once again, there was no advantage of using 99mTc-HDRBC vs. 99mTc-NDRBC. These results demonstrated that small amounts of bleeding might potentially be detected with scintigraphy; they also suggest that the limiting factor for detecting small amounts of bleeding may be the level of lung background radioactivity.

Animals↗
PubMed1999

Plasma glutamine status in the equine at rest, during exercise and following viral challenge.

The variation over 24 h of plasma glutamine concentration in nonexercising horses was studied in 3 Thoroughbreds (TB) fed at 1600 h and 0700 h. This indicated a small but regular change associated with feeding. Starting at a mean of 482 mumol/l at 1600 h the concentration increased to 522 mumol/l at 2000 h, falling to 476 mumol/l at 1600 h and increasing again to 525 mumol/l at 2000 h. 'Normal' values were established in 19 part-bred TB horses, lacking clinical signs or remarkable pathology and in light training, by sampling weekly at 1000 h over a 10 week period. The mean concentration was 491 mumol/l. Values were normally distributed with 95% confidence range between horses of 469-512 mumol/l. The s.d. of values within-horse was 28 mumol/l. The acute effect of exercise was investigated in 5 TB horses during i) an exercise simulating the road and tracks phase of a 3-day-event and ii) a sustained high-intensity exercise test (115% VO2max until the pace was no longer maintained). In both tests a transient increase was produced as a direct result of exercise, followed by a decline to a nadir at approximately 3 h post exercise. Pre-exercise resting concentrations, following either test, were approaching pre-values by 24 h recovery. The effect of viral challenge was studied in 6 TB horses exposed to an aerosol of equine influenza virus, subtype H3N8 (A/equine-2 subtype) which caused mild clinical signs. A significant fall in the 1000 h plasma glutamine concentration from a mean of 463 to 342 mumol/l by the 6th day was seen in 5 horses. A more gradual decline was observed in the 6th horse. These findings indicate a similar response to viral challenge in the horse to that in man.

Animals↗
PubMed1999

Modulation of the corticospinal control of ventilation by changes in reflex respiratory drive.

We have determined whether changes in PCO(2) above and below eucapnia modulate the precision of the voluntary control of breathing. Twelve trained subjects performed a compensatory tracking task in which they had to maintain the position of a cursor (perturbed by a variable triangular forcing function) on a fixed target by breathing in and out of a spirometer (ventilatory tracking; at 10 l/min). Before each task, subjects hyperventilated for 5 min, and the end-tidal PCO(2) (PET(CO(2))) was controlled; tracking was then performed separately at hypocapnia, eucapnia, and hypercapnia (PET(CO(2)) approximately 25, 37, and 43 Torr, respectively). Ventilatory tracking error was unchanged during hypocapnia (P > 0.05) but was significantly worse during hypercapnia (P < 0.003), compared with eucapnia; arm tracking error, performed as a control, was not significantly affected by PET(CO(2)) (P > 0. 05). In conclusion, ventilatory tracking performance is unaffected by the eucapnic PCO(2). From this, we suggest that resting breathing in awake humans may be independent of chemical drives and of the prevailing PCO(2).

Adult↗
PubMed1999

Drug use among inner-city African American women: the process of managing loss.

The grounded theory study described in this article investigated illicit drug use in the lives of 32 drug-using women living in two inner-city neighborhoods of a large metropolitan U.S. city. The underlying purpose was to describe the process of how life situations and events influenced the onset of drug use and changes in drug-using behaviors. Analysis of in-depth interviews revealed several themes. The basic social process, managing loss, was identified. Painful feelings of loss resulted from the separation of someone or something from the lives of participants and included death or desertion of a significant other, loss of child custody, and rejection by a significant other. Emotional, physical, and sexual abuse resulted in a loss of ability to give and receive love and trust in oneself or others. Losses resulted in an escalation of drug use. Findings have implications for interventions to assist women in dealing with drug use, violence in their lives, self-care, and parenting.

Adult↗
PubMed1998

Involvement of 3q21 in nodular fasciitis.

Cytogenetic data on nodular fasciitis are sparse. We present a case of this lesion and discuss our results in view of previously reported findings in nodular fasciitis and other benign mesenchymal lesions.

Chromosomes, Human, Pair 3↗
PubMed1998

Fracture patterns at the Medieval Leper Hospital in Chichester.

Humans are constantly at risk of bone fractures, not only when threatened by personal violence, but also by the challenge of daily living. Because fractures are a cross-cultural phenomenon and are one of the more commonly observed skeletal lesions in archaeological collections, their presence provides a unique opportunity to compare living conditions, and thereby assess fracture risk in coexisting cultures. This study analyzed long bone fracture patterns of 212 sexed adults from the medieval leper hospital of St. James and St. Mary Magdalene in Chichester, England. The comparison of this hospital sample to other British medieval skeletal samples examined the level of health manifest in fracture etiology. The fracture frequency for this sample was 15.1%, with males accounting for 85.4% of the fractures. The fracture frequencies from the samples not affiliated with hospitals ranged from 3.3 to 5.6%. Because medieval urban lifestyle was notoriously difficult due to inadequate sanitation and living conditions, the overall health of the population at large was inferior, placing all at similar fracture risk. Therefore, more specific complications associated with the fractures were examined. Osseous modifications of the skeletons due to lepromatous leprosy were associated with 28% of individuals sustaining fractures. However, persons with the milder tuberculoid leprosy do not exhibit skeletal lesions, but are more prone to accident due to the earlier loss of sensory perception and visual impairment. It is argued that the presence of leprosy is underestimated in archaeological populations and may be a major contributing factor to the prevalence of fracture resulting from accidental falls.

Adult↗
PubMed1998

Rib lesions and tuberculosis: the palaeopathological evidence.

SETTING: Tuberculosis diagnosis in past populations relies on lesions in the spine and major weight bearing joints of the body. Bone formation on visceral surfaces of ribs has also been suggested to be the result of chronic pulmonary disease. OBJECTIVE: To test whether these lesions are the result of pulmonary infection (most likely tuberculosis), by reviewing past work, and to discuss whether these lesions could be considered another diagnostic criterion for pulmonary tuberculosis. DESIGN: A review of the literature on new bone formation on ribs, and consideration of further evidence from archaeological skeletal material from the UK. RESULTS: Results from modern studies suggest that bone formation on ribs is often the result of pulmonary tuberculosis, that lesions are relatively common in archaeological skeletal material, and that some skeletons have rib lesions plus pathognomonic changes of tuberculosis. CONCLUSION: Evidence suggests that new bone formation on visceral surfaces of ribs should be considered a possible indicator of tuberculosis. If accepted, historical evidence, when correlated with rib data, produces closer approximations to the frequency of the disease in the past. This study indicates the importance of palaeopathology in identifying sometimes subtle lesions that may not be noted by clinicians because of their non-visibility on radiographs.

Humans↗
PubMed1998

Post exercise changes in compartmental body temperature accompanying intermittent cold water cooling in the hyperthermic horse.

Whereas the efficacy of cold water cooling of horses has been demonstrated by several studies, the dynamics of temperature changes within and between compartments (primarily muscle, blood [core], skin and deep core [rectal]) have not been investigated. Changes in body temperature associated with cold water cooling were investigated in the hyperthermic horse. Muscle (TMU), pulmonary artery (TPA), rectal (TREC), tail-skin (TTSK) and coat surface (TCOAT) temperatures, were monitored continuously in 5 Thoroughbred horses during and after exercise in hot humid (30 degrees C and 80% RH) conditions on a treadmill. Horses were cooled in the hot humid environment with cold water (approximately 6 degrees C) for 6 30 s periods. Between each 30 s cooling period the horses stood for 30 s. A total of 180 l of cold water was applied. Horses were monitored for a further 4 min following the final cooling period. From the end of exercise to the end of the final cooling (6.5 min), mean (+/- s.e.) rates of decrease for TTSK and TPA were similar (0.8 +/- 0.1 and 0.8 +/- 0.1 degrees C/min, respectively). The effects on TMU and TREC were less marked, with average rates of 0.2 +/- 0.1 and 0.0 +/- 0.1 degrees C/min, respectively. During the first 4 min of cooling, TPA fell during the 30 s period of water application and rose during each 30 s period of standing. When TPA fell below approximately 36.5 degrees C, these variations were suppressed and TPA rose steadily, despite continued applications; TREC and TMU continued to fall, although less rapidly than before. These observations are consistent with the onset of skin vasoconstriction at low TPA. The mechanism is mediated through a cooling of circulating blood volume providing a greater capacity for heat transfer between muscle and circulation. Intermittent application of cold water (approximately 6 degrees C) improves heat removal without apparent deleterious effects and is well tolerated. Even when hypothermia develops (based on TPA), muscle and rectal temperatures continue to fall.

Animals↗
PubMed1998

Low-level chromosome 12 amplification in a primary lipoma of the lung: evidence for a pathogenetic relationship with common adipose tissue tumors.

Cytogenetic analysis of a primary lipoma of the lung removed from a 56-year-old woman revealed the presence of a supernumerary marker chromosome in all metaphase cells analyzed; namely, 47,XX,+mar. To the best of our knowledge, this is the first cytogenetic description of a primary lipoma of lung. Genetic analysis of intramuscular lipoma, atypical lipoma, and well-differentiated liposarcoma have revealed the presence of one to three supernumerary ring or giant marker chromosomes composed of chromosome 12 segments as the characteristic anomaly. The marker chromosome in the present case was shown to be composed entirely of chromosome 12 material by subsequent analysis with a chromosome 12-specific paint probe and fluorescence in situ hybridization. Thus, analogous to intramuscular lipoma, atypical lipoma, and well-differentiated liposarcoma, extra chromosome 12 material is present. These findings support a pathogenetic relationship between this lipoma of unusual anatomic location and common adipose tissue tumors.

Chromosome Aberrations↗