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Biomedical subjects

C Clercx

Publications and source records attributed to C Clercx.

At least 37 records · Page 2Linked to original sources
PubMed1996

Cardiac performance in conscious healthy dogs during dobutamine infusion.

The aim of this study was to determine the cardiac performance of conscious healthy dogs during stimulation with dobutamine. Eight healthy unsedated beagle dogs were used. Cardiac output was measured by the thermodilution technique and blood pressures by extravascular pressure transducers. Dobutamine challenge at a dosage ranging from 27.5 to 50 micrograms kg-1 min-1 induced a significant rise in cardiac power index (CPI), cardiac index (CI), stroke index (SI) and heart rate (HR) and a significant decrease in pulmonary vascular resistance (PVR) and systemic vascular resistance (SVR). The highest CPI was 2.05 times greater than its basal resting value. The CI was primarily responsible for this increase in CPI. The SI and HR contributed approximately 55 per cent and 45 per cent respectively of the maximal increase in CI.

Analysis of Variance↗
PubMed1996

Imprint and brush cytology in the diagnosis of canine intranasal tumours.

Fifty-four dogs with nasal tumours were included in this study. Based on histopathology 52 tumours were malignant (36 epithelial and 16 mesenchymal) and two were benign (one oncocytoma and one pleiomorphic adenoma). Malignancy was significantly more frequently diagnosed by imprint cytology (81 per cent of the cases) than by brush cytology (56 per cent). Brush cytology was a significantly more sensitive technique in epithelial than in mesenchymal tumours, while the sensitivity of imprint cytology was not affected by the histological type. Brush cytology determined an epithelial origin in 88 per cent of epithelial tumours, and imprint cytology in 90 per cent. In mesenchymal tumours, the scores were significantly lower, the histological type being determined in only 20 per cent and 50 per cent, using brush and imprint cytology, respectively.

Adenocarcinoma↗
PubMed1995

Closantel intoxication in a dog.

A case of overdosage with closantel, a salicynalide derivative, in a dog is described. The dog received 6 times the recommended dosage. Closantel induced optic neuritis, retinal degeneration, partial deafness, hepatotoxicosis and myopathy. Only the blindness was irreversible. The therapy included albumin administration to reduce the acute toxicity of closantel.

Albumins↗
PubMed1994

Acute polymyopathy after carbamate poisoning in a dog.

The acute polymyopathy in a seven-year-old German shepherd dog was attributed to the muscular hypertonia, tremors and seizures which developed during the acute phase of carbamate poisoning. After two days of generalised muscular rigidity, the dog adopted a characteristic fetal position which could be explained by the imbalance between the injuries to the extensor and flexor muscles. The polymyopathy resolved gradually over the course of a week.

Acute Disease↗
PubMed1993

Measurement of total respiratory impedance in dogs by the forced oscillation technique.

The resistance (Rrs) and reactance (Xrs) of the total respiratory system were determined at various frequencies in 14 healthy conscious beagle dogs. A pseudorandom noise pressure wave was produced at the nostrils of the animals by means of a loudspeaker adapted to the nose by a tightly fitting mask. A Fourier analysis of the pressure and flow signals yielded mean Rrs and Xrs, over 16 s, at frequencies from 2 to 26 Hz. The influence of the posture of the dog, the position of its head, the linearity of the respiratory system, the reproducibility of the method and the effects of upper and lower airway obstructions were studied. In sitting and standing healthy dogs with the head in the extended position, Rrs values increased progressively with frequency from 5.4 +/- 0.4 (SEM) cmH2O L-1s at 6 Hz up to 8.8 +/- 0.7 cmH2O L-1s at 26 Hz, the mean resonant frequency being 6.1 +/- 0.5 Hz. No significant differences were observed between measurements performed with the head in the normal or the extended position. In a recumbent posture, all Rrs values were increased but Rrs was still dependent on the frequency in the same way (7.1 +/- 0.7 cmH2O L-1s at 6Hz up to 10.0 +/- 0.5 cmH2O L-1s at 26 Hz). Tracheal compression also induced higher Rrs values without changes in the frequency dependence or in the resonant frequency. In anaesthetized dogs, airway obstruction was induced by inhalation of histamine (4 mg/ml for 5 min; the Rrs values tended to decrease with increasing frequency, and the resonant frequency was markedly increased.

Airway Obstruction↗
PubMed1991

Comparison of inhalation-to-perfusion ratio in anesthetized dogs with barrel-shaped thorax vs dogs with deep thorax.

Interregional, as well as intraregional (local), distributions of the inhalation-to-perfusion ratio were analyzed in the lungs of 20 prone anesthetized healthy dogs--10 dogs with barrel-shaped thorax (Beagles) and 10 dogs with deep thorax (Greyhound-type dogs)--using 99mTc inhalation-perfusion lung scintigraphy. Dorsoventral and lateral views were analyzed. In both types of dogs, the ratio between the mean inhalation and perfusion values (interregional mismatching factor gamma) decreased from craniad to caudad and the decrease was more sustained in the right than in the left lung. However, the total decrease was less in Greyhound-type dogs than in Beagles (cranial-to-caudal decrease of 14 and 27%, respectively, in the left lung, and 62 and 56%, respectively, in the right lung). The dorsal-to-ventral distribution of gamma was different in the 2 types of dogs. In Beagles, it increased from dorsal to ventral zones by about 50% of the initial dorsal zone value, whereas in Greyhound-type dogs, only a slight dorsal-to-ventral decrease was evident, with the exception of the more ventral zone. Differences in the intraregional mismatching factor (rho) indicated that the intraregional inhalation-to-perfusion inequalities were more pronounced within the caudal regions and within the ventral zones of the lungs in both types of dogs, and in the more cranial zones in the lungs of Beagles. However, the degree of intraregional mismatching was generally lower in Greyhound-type dogs. Thus, the gravitational force is not the dominating determinant of interregional or intraregional inhalation-to-perfusion ratio distributions in the lungs of anesthetized prone dogs.(ABSTRACT TRUNCATED AT 250 WORDS)

Aerosols↗
PubMed1989

Quantitative analysis of radioaerosol inhalation and perfusion scintigraphy in dogs.

A method was developed for the analysis of 99mTc MAA perfusion and 99mTc phytate colloid aerosol inhalation distribution patterns. Scintigraphic images were compared, based on the activity of corresponding picture elements (pixels). The possible mismatching in a pixel between both distributions was expressed in terms of a regional mismatching (common to a whole region) and an additional intraregional mismatching at the individual pixel level. Parameters characterizing the degree of regional and intraregional mismatching were introduced. The method was applied to 16 anesthetized healthy dogs in which a cranial-to-caudal gradient in regional mismatching was found.

Aerosols↗
PubMed1989

Pulmonary scintigraphy in canine lobar and sublobar airway obstruction.

The intrapulmonary distribution of the inhalation-to-perfusion ratio (I/P) was studied after placement of an obstruction in a sublobar bronchus (SLO) or in a lobar bronchus (LO) in 17 anesthetized prone (sternal recumbent) dogs. Placement of an SLO or LO did not induce any significant changes in the standard ventilatory and hemodynamic parameters measured. With the use of 99mTc aerosol inhalation combined with 99mTc perfusion lung scintigraphy, parameters quantifying the inhalation (I) to perfusion (P) mismatching at regional as well as at intraregional levels were calculated. The SLO increased the relative ventilation to the lung containing the obstruction, induced a shift of blood from the obstructed segment to the rest of the same lung, and increased the ratio between the mean I and the mean P (regional mismatching factor) in both the obstructed segment and the lung containing the obstruction. The LO diverted air and blood away from the obstructed lobe to the contralateral lung, but blood to a lesser extent. The LO decreased the regional mismatching factor in the obstructed lobe but also in the lung containing the obstruction. It also increased significantly the intraregional I to P mismatching in the obstructed lobe as well as in the rest of the same lung. After withdrawal of LO and reinsufflation of the collapsed lobe, blood continued to leave this lobe, while the withdrawal of SLO allowed recovery of the initial perfusion. This suggests that both hypoxic vasoconstriction and mechanical factors such as vascular distortion are involved in the blood shifts observed, and require some delay to be relieved. It is concluded that in dogs compensating mechanisms such as collateral ventilation are very effective. In case of SLO, I to the lung involved is increased. In case of LO, vasoconstriction in response to alveolar hypoxia could not fully compensate for the decreased I to the obstructed lobe.

Aerosols↗
PubMed1989

Scintigraphic analysis as a diagnostic tool in canine experimental lung embolism.

Scintigraphic changes occurring after lung embolism induced by intravenous administration of agar were assessed in 10 anesthetized prone dogs. Using 99mTc aerosol inhalation combined with 99mTc perfusion scintigraphy, parameters quantifying the regional distribution of the inhalation-to-perfusion ratio (I/P) and the degree of intraregional I-P mismatching were calculated from dorsoventral views (DV) for 6 equidistant cranial-to-caudal left and right lung zones before (B) and after acute embolism (PE). Postmortem examination was performed in 7 dogs. Several perfusion defects could be detected in either the conventional or the functional (I-P) lung scintigrams. Nevertheless, PE did not induce significant changes in blood gases. On the scintigrams, the outer zones appeared to be the most heavily embolized. The regional I/P ratio was increased in the more caudal and cranial parts of both lungs. However, postmortem examination of the lungs showed the presence of emboli diffuse in all lobes. Their presence was revealed in all zones by a significant increase of an intraregional mismatching index rho and especially of an intraregional mismatching factor mean value of gamma. After acute embolism, blood was redistributed to perihilar regions, especially in the right lung. This redistribution process continued during the experiment. In conclusion, the use of combined aerosol inhalation/perfusion lung scintigraphy with quantitative analysis provides a sensitive method for the detection of pulmonary embolism.

Aerosols↗
PubMed1989

Effects of age and breed on the phospholipid composition of canine surfactant.

To investigate possible age- and breed-related changes in the composition of canine pulmonary surfactant, we determined the phospholipid patterns of surfactants isolated by bronchoalveolar lavage of 3 age categories of beagles (3-7 months; 3-7 years; 12 years and older) and of 1 group of greyhounds (4-14 years). There was a significant (p = 0.01) increase in the proportion of phosphatidylcholine in surfactant with age, whereas the proportions of phosphatidylserine and sphingomyelin were significantly lower in old beagles compared to young dogs. Although the differences were generally rather small, they may nevertheless be of biological importance, as was indicated by comparing the minimal surface tensions of lavage fluids obtained from young and old beagles. It is attractive to speculate that the shift in surfactant lipid composition could be 1 of the mechanisms that permit efficient lung function in old dogs, despite changes in morphology and mechanics in the aging lung. The phospholipid composition of surfactant isolated from greyhounds differed significantly from that in beagles. The surfactant of greyhounds was enriched in phosphatidylglycerol compared to all age groups of beagles. The degree of saturation of surfactant phosphatidylcholine was also higher in greyhounds, although this differences was significant only when compared to young and middle-aged beagles.

Aging↗
PubMed1989

Effect of posture and anaesthesia on the distribution of pulmonary perfusion and lung configuration in beagle dogs.

To investigate the effect of posture and anaesthesia on the topographical distribution of pulmonary perfusion in canine lungs, the changes in lung shape, configuration and regional perfusion were assessed in healthy beagle dogs, using a repeated 99mTc perfusion scintigraphic procedure. The general shape of the lung images was similar in standing and prone postures, except for a relative increase of the more ventral zone in the prone posture, ascribed to vertical flattening of the lung associated with enlargement of the ventral zones. Configuration changes revealed a shift of the parenchyma towards the more caudal parts in the prone posture, which suggests a parenchymal compression of the paradiaphragmatic lung zones. The prone posture induced a decreased perfusion to the caudal third of the lung. Anaesthesia induced significant changes in lung shape without an obvious direction. The perfusion to the more ventral as well as to the more cranial zones was reduced. Differences in the perfusion distribution are thought to be mainly due to the pressure exerted by the abdominal content through the diaphragm and to the shift of the blood towards better ventilated lung regions.

Anesthesia↗
PubMed1988

The topographical distribution of the inhalation-to-perfusion ratio in double-muscled and Friesian calves.

Five healthy Friesian calves and five double-muscled Belgian White and Blue calves were studied, using a 99m Technetium (99mTc) aerosol inhalation combined with a 99mTc macroaggregate injection and collimated scintillation counters. The inhalation-to-perfusion ratio (I/P) was calculated for both left and right sides of the thorax at four sites situated at three different levels in the auscultatory area on the same vertical axis and at a more anterior site just behind the scapulohumeral joint. I/P was higher in the left than in the right hemithorax. In both breeds, a vertical and a horizontal gradient were observed. I/P was higher in the lower and in the more cranial zones of the lungs. However the vertical gradient was more pronounced in Friesian calves while the horizontal one was greater in Belgian White and Blue animals. It was concluded that the factors affecting the topographical distribution of pulmonary ventilation and perfusion seem to be different in calves as compared to other species.

Administration, Inhalation↗
PubMed1988

Influence of inertance on measurements of the mechanical properties of the bovine respiratory system.

The observation that dynamic compliance (Cdyn) tended to rise with respiratory frequency (f) in adult cattle led us to reassess the importance of inertial pressures in measuring Cdyn in large animals. Five healthy Friesian cows were selected for their ability to show an increase of f without significant change in tidal volume (VT). Dynamic compliance was measured three times, both at the resting f (21 +/- 1 cpm), and at higher f (49 +/- 3 cpm), obtained by an artificial increase in the dead space of the breathing mask. Frequency-response characteristics of the measuring instruments were matched up to 12 Hz. The inertia of the lungs and gas stream (In) was calculated as the ratio of the accelerative pressure change to the simultaneous change in volume acceleration. Inertance was also estimated from the dimensions of the bovine airways and from the relative linear flow velocities reported by Rohrer (1915). Dynamic compliance measured during rapid breathing was significantly higher (p less than or equal to 0.01) than base-line values. Dynamic compliance was strongly correlated with f (r = +0.96). Measured and estimated In were 0.002 and 0.003 kPa.sec2.L-1 respectively. Dynamic compliance did not differ significantly from base-line values when it was corrected for the estimated inertance effect.

Animals↗
PubMed1987

In vivo animal demonstration of the effect of vasoactive drugs using 195mAu and gamma camera techniques.

195mAu, an ultrashort-lived (physical half life = 30.5 s) generator-produced radionuclide, has been used in an animal model to study, by gamma camera techniques, the peripheral effects of the vasoactive drugs norepinephrine and sodium nitroprusside systemically administered or epinephrine (intraarterially) injected at various concentrations. According to the results obtained by the analysis of time activity curves generated from areas of interest drawn on the proximal and distal parts of the limbs, the well known hemodynamic changes induced by these drugs, vasoconstriction (resulting in a decrease of the distal activity recorded), or vasodilatation (shortening the time of radioactivity appearance), could be observed. It is concluded that gamma camera techniques using the ultrashort lived radionuclide 195mAu allow the in vivo study of the effects of vasoactive drugs in an animal model and potentially in clinical situations.

Animals↗
PubMed1987

Radionuclides in lung diagnostics: a new approach. Summary of the first results.

With a 99mTc-labelled aerosol an inhalation (ventilation) image of the lungs was obtained. A lung perfusion image was obtained with 99mTc-labelled macro-aggregates. The data from the gamma camera were stored in a computer and the inhalation-perfusion (I/P) ratio was calculated for the total lung as well as for one half, another selected region, and a local (pixel) area. In the anaesthetised dog in sternal recumbency, the I/P ratio decreased from the cranial to the caudal lung regions. Hence in the dog gravity is not the only determinant of the I/P ratio distribution, as it is assumed to be in man. Position and anaesthesia appeared to influence the distribution of I/P ratios within the lung.

Animals↗
PubMed1987

Mechanical properties of excised calf lungs.

Five isolated calf lungs were suspended in an airtight box used as a ventilator. Lungs were ventilated from the outside at different levels of transpulmonary pressure (Ptp). The static pressure-volume curve characteristics of the lungs were measured. Static compliance (Cstat) was 1.9 +/- 0.37 litres kPa-1 or 25 +/- 5 per cent of total lung capacity kPa-1. At a Ptp of 0.7 kPa, dynamic compliance (Cdyn) and lung resistance (RL) were 1.1 +/- 0.1 litres kPa-1 and 0.126 +/- 0.02 kPa litres sec-1, respectively. Both an increase and a decrease of this level of Ptp induced an increase of RL and a decrease of Cdyn. The ratio Cdyn/Cstat averaged 57 +/- 0.8 per cent. It was concluded that in excised lungs, Cdyn is lower in the calf than in a number of other species and that pulmonary function values measured in vitro are optimum at values of Ptp close to values recorded in vivo in healthy cattle.

Animals↗
PubMed1987

Mechanical properties of excised calf lungs: effects of airway obstruction with beads.

Isolated lungs of five calves were suspended in an airtight box used as a ventilator. Lungs were ventilated from the outside at different levels of transpulmonary pressure. Dynamic compliance (Cdyn) and total pulmonary resistance (RL) were measured. These pulmonary function values were also measured during central and peripheral airway obstructions. It was demonstrated that both central and peripheral obstructions induced significant variations of Cdyn and RL. However, decrease of Cdyn was greater and increase of RL was smaller during a peripheral obstruction than during a central one.

Airway Obstruction↗