Biomedical subjects

D Desmecht

Publications and source records attributed to D Desmecht.

49 records · Page 3Linked to original sources

PubMed1990

Respiratory-induced variability of pulmonary arterial pressure measurements in cattle.

The purpose of this study was to investigate the variability of the peak systolic (PAPs) and the end diastolic (PAPd) pulmonary arterial pressures induced by intrapleural pressure changes in cattle. The pleural pressure (Ppl), the electrocardiogram and the pulmonary arterial pressure (PAP) were simultaneously recorded in five healthy calves under three different conditions, i.e. normoxia (N), normoxia with an added airflow resistance (R) and hypoxia (H). PAPs, PAPd and their corresponding transmural pressures were measured and averaged over 10 successive regular cardiac cycles. The maximum Ppl changes (max delta Ppl) were measured on the same tracings. The variance and coefficients of variation were calculated for each set of vascular measurements. Max delta Ppl was significantly increased with regard to N values during R and H conditions. This increase in max delta Ppl induced a simultaneous rise in the variability of PAP measurements, while in each condition, this variability was greatly lowered by use of the corresponding transmural pressure. It was concluded that, in calves with high max delta Ppl, the influence of respiration on PAP becomes considerable. In such cases, the use of transmural pressures rather than luminal pressures can greatly reduce the variability of these pulmonary pressure measurements and therefore increase their sensitivity.

Airway Resistance↗

PubMed1990

Synchronization of locomotion and respiration in trotting ponies.

The aim of the present experiment was to investigate the hypothesis that there is a respiration-locomotion coupling in trotting equines. Therefore the respiratory airflow (V), the gastric pressure (Pga) and pleural pressure (Ppl) changes and the step frequency (SF) were simultaneously recorded in 5 trotting ponies (body weight: 255 +/- 15 kg; age: 3.5 +/- 0.4 years). Airflow was measured using a Fleisch pneumotachograph fixed on a face mask. Esophageal and gastric balloon catheters coupled to pressure transducers allowed the recording of Ppl and Pga. The exercise was performed on a treadmill and consisted of 1 min walking (1.5 m.s-1), 1 min slow trotting (3.0 m.s-1)(Trot 1) and 3 min fast trotting (3.5 m.s-1)(Trot 2). Data were continuously recorded before and during exercise. At walk and Trot 1, none of the ponies displayed a coupling between SF and the respiratory frequency (RF). In one pony, SF and RF were coupled at a constant ratio of 2:1 during Trot 2 while two other ponies displayed the same coupling only up to the second minute of Trot 2. In the two last ponies, a coupling occurred at the third minute of Trot 2. In all ponies, the peaks in Pga occurring during expiration occurred always simultaneously with the first and/or the second peak V, whether or not there was a relationship between SF and RF. On the other hand, when SF and RF were coupled, the first part of inspiration was always simultaneous to a decrease in Pga. It was concluded that in trotting ponies respiration and locomotion are not always independent and that the abdominal piston may act in synergy with the respiratory pump in some phases of the breathing cycle.

Animals↗

PubMed1990

A field study of post-exercise values of blood biochemical constituents in jumping horses: relationship with score, individual and event.

The variability of the post-exercise values (PEV) of blood lactate and of some other blood constituents were studied in 8 healthy and fit jumpers through 5 national competitions of equal difficulty. The effects of factors such as the individual, performance and competition on these PEV were analysed. Venous blood was sampled immediately after the 5 show-jumping contests and was analysed for packed cell volume (PCV), blood lactate, blood glucose (GLU), total plasma protein (TPP), bicarbonate (HCO3-), sodium (Na+), potassium (K+), chloride (Cl-), calcium (Ca2+), serum activities of lactate dehydrogenase (LDH), creatine phosphokinase (CPK), glutamic-oxalacetic transminase (GOT) and gamma glutamyl transferase (gamma GT). PEV of these 13 blood parameters were analysed using a fixed linear model which included the effect of horse, score and competition and their respective interactions. The analysis of the influence of each of the 3 fixed variables showed that (1) there was no relationship between the PEV variations and the score; (2) there were significant (P less than 0.05) variations induced by the competition in Na+, Ca2+, TPP, LDH and GLU, and (3) there were significant interindividual variations as regards Ca2+, TPP, CPK, gamma GT and PCV with P less than 0.05, LDH with P less than 0.01 and blood lactate with P less than 0.001.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1990

Ventilatory mechanics in healthy calves during helium-oxygen breathing.

The mechanics of breathing was investigated in six healthy calves breathing either air or a mixture of 79% helium and 21% oxygen (He-O2). Intrapleural pressure (Ppl) was measured with an esophageal balloon catheter and transpulmonary pressure was obtained by subtracting the mouth pressure (Pm) from Ppl. Respiratory airflow (V) was measured using a Fleisch pneumotachograph N degrees 3 and tidal volume (Vt) was electronically derived by integrating V with respect to time. Respiratory airflow, Vt, Ppl and Pm were simultaneously recorded while the calves breathed first air (1 min), secondly He-O2 (1 min) and finally air again (1 min). The pulmonary function values were calculated on the tracings and the He-O2 values were compared to the corresponding "air" values. The ventilatory response to resistance unloading was characterized by a significant increase in minute volume exclusively due to an increase in respiratory frequency, while Vt remained unchanged. A decrease of 32% in the total pulmonary resistance (RL) and 16% in the work per litre of ventilation (Wrm/l) were observed when calves breathed He-O2. The effect of the He-O2 on RL and on Wrm/l suggests that, in the bovine species, airflow turbulances in the upper part of the respiratory tract play a significant role in the total airways resistance.

Airway Resistance↗

PubMed1990

Effect of show jumping on heart rate, blood lactate and other plasma biochemical values.

This study investigated some physiological responses to exercise performed by a horse during show jumping. The effects of jumping on heart rate (HR), blood lactate (LA) and some other blood values were studied in nine normal horses participating at the Belgian Junior Championship. Venous blood was sampled before and immediately after the show jumping and was analysed for packed cell volume, LA, blood glucose (GLU), total plasma protein, bicarbonate, sodium, potassium (K+), chloride, calcium and activities of plasma lactate dehydrogenase, creatine phosphokinase (CK) aspartate amino transferase and gamma glutamyl transferase (GGT). A heart rate recorder placed under the saddle allowed the continuous recording of HR from the warm-up until 2 mins after the event. The completion of the jumping induced significant changes in all values, except in K, GLU and GGT. Resting values of LA and HR were 0.53 +/- 0.05 mmol/litre and 43.9 +/- 1.9 beats/min respectively. Post exercise LA reached a mean value of 9.04 +/- 0.9 mmol/litre, and, during the jumping, HR rose to a peak of 191.4 +/- 3.8 beats/min. The results of this study demonstrate that, although the speed and duration of such an exercise are low, show jumping represents a severe exertion which requires the use of anaerobic metabolism. This implies that the training schedule of jumpers must include power training in order to improve their anaerobic capacity.

Analysis of Variance↗

PubMed1990

Comparison of the adrenocortical response to both pharmacological and physiological stresses in sport horses.

Seven sport horses were investigated to compare physiological and pharmacological stresses on the plasma glucocorticosteroid levels. Venous blood was sampled and analysed for cortisol concentrations before and after each type of stress. The physiological stress was induced by the completion of a cross-country and the pharmacological one, by an intravenous ACTH administration (200 micrograms) in the same horses, one week after the course. Both exercise and ACTH injection induced a highly significant cortisol increase of 79 +/- 0.10% and 160 +/- 0.18%, respectively. The relative plasma cortisol increases due to exercise on the one hand, and due to ACTH administration on the other hand, were correlated with a coefficient of 0.82. It was concluded that the plasma cortisol increase induced by a standardised pharmacological stress could be used in order to predict the exercise-induced stress response.

Adrenal Cortex↗

PubMed1989

Inertance of the respiratory system in ponies.

The purpose of the present work was to measure the pulmonary inertance (IL) in ponies and to analyze its potential influence on the mechanics of breathing and on their aptitude to increase ventilation during exercise. Five healthy ponies 2.4-4 yr old [mean wt 255 +/- 15 (SE) kg] were used. On the one hand, inertance of the respiratory system (Irs) was computed from the value of the resonant frequency (fr) measured by the forced oscillation technique. On the other hand, respiratory airflow, tidal volume (VT), and transpulmonary pressure (PL) changes were recorded while the ponies were performing a light treadmill exercise, and IL was calculated as the ratio of the associated differences in inertial pressure (delta Pin) to volume acceleration (delta V). Respiratory airflow and VT were measured with a Fleisch pneumotachograph (no. 5) and PL with an intraesophageal balloon catheter. First, the protocol was carried out with the ponies breathing air and He-O2, second, while the ponies breathed through two additional tubes (100 cm long, 3 cm ID), then one, and finally none, fixed on the Fleisch pneumotachograph. Finally, the contribution of the extra- vs. the intrathoracic airways to IL was estimated by measuring the lateral midtracheal pressure recorded simultaneously with the aforementioned parameters. The values of Irs calculated with fr and of IL calculated on the basis of the delta Pin-delta V ratio were 29.8 +/- 0.4 and 19.8 +/- 1.0.10(-4) kPa.l-1.s-2, respectively. During He-O2 breathing IL decreased about three times; this result was similar to the predicted decrease based on gas density only.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMedDate not supplied

Oxygen transport chain in double-muscled blue Belgian cattle.

The physiological peculiarities of the oxygen transport chain in double-muscled Blue Belgian cattle are described. The investigations performed at several levels of the oxygen transport chain suggest that the increased susceptibility of these cattle to stress, resulting mainly in respiratory diseases, is due to an insufficient functional reserve capacity mainly involving the pulmonary and cardiovascular systems. The resulting lack of 'functional hardiness' of the oxygen transport chain is seen in those double-muscled cattle which do not react in an appropriate or predictable way when submitted to a hostile environment.

Animals↗

PubMedDate not supplied

Effects of growth and breed on direct static measurements of chest wall compliance in cattle.

Chest wall compliance (CW) was measured in 59 conscious standing calves, aged six to 162 days, which were breathing air spontaneously through a face mask. The airways were occluded at the end of inspiration in order to elicit the Hering-Breuer reflex, the effectiveness of which was ensured by the presence of a plateau on the tracings of airway opening and oesophageal pressure (Pes). CW was measured directly from the inspired volume of the occluded breath and changes in Pes generated by the recoil of the relaxed chest wall. This airway-occlusion technique yielded reproducible CW values similar to those measured by classical invasive methods. The ratio of CW to bodyweight in the growing calves (sCW) ranged from 2.2 to 11.5 ml cmH2O-1 kg-1 and was correlated negatively with age: (log sCW = 0.91-0.003 x age, r = 0.68), the rate of decline corresponding well to the multispecies allometric growth relationship.

Abdominal Muscles↗

PubMedDate not supplied

Enzyme-histochemical detection of a chymase-like proteinase within bovine mucosal and connective tissue mast cells.

The presence of chymase-like proteinase in bovine mast cells was investigated by an enzyme-histochemical technique (naphthol-AS-D-chloroacetate as substrate) in normal skin, primary bronchus, lung and duodenum. The counts and distribution of chymase-positive and toluidine blue-positive mast cells were compared by means of successive staining. Mast cells with chymase-like activity were detected in all areas, but their proportion was greater in connective than mucosal tissues, with the exception of the skin. These results contrast with those obtained in rodents, in which chymase-like proteinases are detected in all tissues and also in all mast cells. Bovine mast cells are closer to those of human beings, in which chymase-containing mast cells predominate in connective tissues, including skin. The results suggest that more than one chymase subset is present, at least in duodenum. The possible occurrence of dual-specific chymase mast cells, as in other ruminants, is discussed.

Animals↗

PubMedDate not supplied

Effect of intravenous platelet-activating factor on bovine pulmonary mast cells.

The effect of platelet-activating factor (PAF) on bovine pulmonary mast cells (MCs) was investigated in calves aged 1-4 months. PAF was administered over a 5-min period at a rate of 50 ng/kg/min to six animals, which were killed approximately 10 min later. No macroscopical lesions were observed in the lung tissue of five control calves. On semi-thin toluidine-blue stained sections, MC cytoplasm showed profuse deep-blue granulation. In the lung tissues of PAF-treated calves, striking interstitial, alveolar and interlobular oedema and emphysema were observed. MC granules occurred at the periphery of the cytoplasm and MC nuclei were easily detectable. Moreover, the number of granules in the MC cytoplasm was remarkably low. A few granules with some metachromatic material were sometimes detected outside the cell limits. Ultrastructurally, the matrix pattern of the MC granules in lung tissues of control calves was either amorphous or granular. In lung tissues of the PAF-treated calves, the granular matrix pattern was pronounced, varying from fine- to coarse-grained, and the MCs were of reduced size, with many filiform processes and exocytotic vesicles. These findings indicate that pulmonary MC degranulation was induced by PAF in healthy calves.

Animals↗

PubMedDate not supplied

Characterization of the caprine (Capra hircus) beta-2 integrin CD18-encoding cDNA and identification of mutations potentially responsible for the ruminant-specific virulence of Mannheimia haemolytica.

The leukocyte integrins play a critical role in a great number of cellular adhesive interactions during the immune response. We describe here the isolation and characterization of the caprine beta(2) (CD18) sub-unit, common to the leukocyte beta(2)-integrin family. The deduced 770-amino-acid sequence reveals a transmembrane protein with 80, 81, 83, 96 and 99% identity with its canine, murine, human, bovine and ovine homologues respectively. Analysis of CD18 sequences emphasizes the functional importance of the beta(2) sub-unit I-like domain, and included metal ion-dependent adhesion site-like motif and confirms that of the cytoplasmic tail. Moreover, comparisons of ruminant versus non-ruminant CD18 sequences allowed the identification of 16 potential mutation sites that could be held responsible for the unique virulence of Mannheimia haemolytica for ruminants. Mannheimiosis is known to be the major respiratory disease among ruminants, whereas it is not pathogenic for other mammals, an observation that has been attributed to a specific interaction between M. haemolytica leukotoxin and ruminants' CD18. Therefore, the data provided here offer the possibility to explore new avenues in studies based on the caprine model and provide key information for future studies aimed at elucidating the molecular mechanisms underlying the ruminant-specific virulence of M. haemolytica.

Amino Acid Sequence↗

PubMedDate not supplied

Nonresponsive generalized bacterial infection associated with systemic lupus erythematosus in a Beauceron.

A case of concurrent canine systemic lupus erythematosus (SLE) and generalized bacterial infection in a six-year-old female Beauceron is reported. The dog presented with purulent nasal and ocular discharges, skin lesions (including seborrhea, hyperkeratotic areas, and papules as well as ecchymoses around the eyes, on both sides of the pinnae, and on the vulva), generalized lymph node enlargement, a mitral murmur, and lameness. Later, facial swelling, a retrobulbar abscess, and a cough also developed. Occurrence of a generalized bacterial infection was established by culture of group-C, beta-hemolytic Streptococcus from the throat, the mouth, a biopsy site (popliteal lymph node area), the retrobulbar abscess, and the lung. The diagnosis of SLE was based on the clinical signs and particularly on the occurrence of antinuclear antibody (ANA) and antidoublestranded-desoxyribonucleic acid (ds-DNA) antibody. Interestingly, the latter type of antibodies were also detected in two young female puppies whelped by this dog. Salient histological findings included an extreme cell depletion of the lymph nodes and spleen and severe pneumonitis and peribronchiolitis. The results of this case indicate that a definite diagnosis of canine SLE can, at times, be made on the basis of the presence of serum ANA and ds-DNA antibodies.

Animals↗