Biomedical subjects

A Autefage

Publications and source records attributed to A Autefage.

7 recordsLinked to original sources

PubMed1991

Bone cutting.

Bone cutting has always been a problem for surgeons because bone is a hard living material, and many osteotomes are still very crude tools. Technical improvement of these surgical tools has first been their motorization. Studies of the bone cutting process have indicated better features for conventional tools. Several non-conventional osteotomes, particularly ultrasonic osteotomes are described. Some studies on the possible use of lasers for bone cutting are also reported. Use of a pressurised water jet is also briefly examined. Despite their advantages, non-conventional tools still require improvement if they are to be used by surgeons.

Bone and Bones↗

PubMed1990

Distribution of material injected intramuscularly in dogs.

A radiopaque marker was injected, using needles of various lengths, into the cervical musculature, the lumbar epaxial musculature, and the cranial and caudal muscular masses of the thighs of anesthetized dogs. After this procedure, the dogs were euthanatized and deep-frozen. The bodies were then sectioned, and the slices were radiographed to determine the fate of the injected material. Material that was injected into the neck or caudal region of the thigh was determined to be located in the muscle bellies or dispensed throughout the intermuscular fascial sheaths. In contrast, material injected into the lumbar area and cranial region of the thigh was located entirely in the muscle bellies. It was concluded that the best sites for injection in dogs are the lumbar epaxial musculature or the quadriceps femoris muscle when IM administration is imperative.

Animals↗

PubMed1988

Diurnal and episodic variations of plasma hydrocortisone concentrations in horses.

Using a specific high-performance liquid chromatographic technique, plasma hydrocortisone values were measured hourly in 6 horses and every 10 minutes in 4 horses over 24 hours. Both circadian and episodic variation was observed. The mean plasma hydrocortisone concentration was a maximum of 58.8 +/- 9.54 ng/ml at 9.19 +/- 0.59 hr and a minimum of 27.85 +/- 6.85 g/ml at 21.19 +/- 0.59 hr. The number of episodes of secretion was 10.0 +/- 1.41; the mean amplitude and duration of peak were 26.21 +/- 3.71 ng/ml and 105.25 +/- 21.24 min respectively.

Animals↗

PubMed1988

Hydrocortisone secretion: production rate and pulse characterization by numerical deconvolution.

Based on serial blood sampling over 24 h, hydrocortisone was shown to be secreted episodically in the horse. The purpose of the present experiment was to characterize peaks and troughs by analyzing the instantaneous secretion rate profile obtained by a deconvolution technique rather than from the plasma concentration time profile. Kinetic parameters of hydrocortisone were determined following intravenous bolus and intravenous perfusion of hydrocortisone. Stationary and nonlinearity of hydrocortisone disposition were demonstrated. With the use of clearance values calculated from constant perfusion administration, the 24-h hydrocortisone production rate was estimated at 0.46 +/- 0.08 mg.kg-1.24 h-1. The instantaneous secretory profile was reconstituted by deconvoluting the plasma concentration profile using structural parameters determined from the bolus hydrocortisone administration. When this secretory profile was subjected to a pulse analysis program, the number of detected peaks was found to be 17.25 +/- 1.26 and the mean peak duration 34.01 +/- 5.52 min. The total duration of secretory activity was estimated at 582.5 +/- 63.97 min. By comparison, when the plasma concentration profile was analyzed directly, the number of peaks was only 10.0 +/- 1.41 but their mean duration was much longer, i.e., 105.25 +/- 21.24 min. The origin of these differences and the advantages and limits of deconvolution analysis are discussed.

Animals↗

PubMed1987

Pharmacokinetics of methylprednisolone succinate, methylprednisolone, and lidocaine in the normal dog and during hemorrhagic shock.

Pharmacokinetics of methylprednisolone succinate and methylprednisolone following methylprednisolone sodium succinate administration were studied in five dogs under normal conditions and then during a severe hemorrhagic shock. In order to evaluate hepatic blood flow, lidocaine clearance was simultaneously measured. In the normal state, the clearance of methylprednisolone succinate was 1.64 +/- 0.499 L/h/kg and its half-life was 15.33 +/- 3.84 min. The systemic availability of methylprednisolone from methylprednisolone succinate was 59.9 +/- 8.3%, and the maximal methylprednisolone concentration was observed after a delay of 7.68 +/- 6.31 min. Using a reservoir technique in anesthetized dogs, severe hemorrhagic shock was obtained. Changes in lidocaine clearance indicated a subsequent reduction of hepatic blood flow. The clearance of methylprednisolone succinate decreased to 0.488 +/- 0.240 L/kg/h, and the half-life increased to 40.66 +/- 23.48 min. The exact availability of methylprednisolone from methylprednisolone succinate during shock was not calculable because methylprednisolone kinetics were time dependent. The plasma methylprednisolone concentration was relatively high and persistent during the shock. It was concluded that methylprednisolone sodium succinate is a prodrug which can be released in sufficient quantities as its active moiety (i.e., methylprednisolone) during severe hemorrhagic shock in the dog. In addition, after a single intravenous administration, the slow process of methylprednisolone elimination may give sustained methylprednisolone concentrations for several hours.

Animals↗

PubMed1986

Synovial fluid and plasma kinetics of methylprednisolone and methylprednisolone acetate in horses following intra-articular administration of methylprednisolone acetate.

Synovial fluid and plasma kinetics of methylprednisolone acetate (MPA) and methylprednisolone (MP) after a single intra-articular administration of MPA at a therapeutic dose (111 mg in toto) was measured in five horses. MPA was detected in synovial fluid for two to six days post injection and MP, which results from synovial MPA hydrolysis, was present in pharmacologically significant concentrations for 4.8 to 39 days, depending on the horse. MPA synovial concentration was maximal (289 +/- 284 micrograms/ml) at the first sampling time (2 h after administration) and MP synovial concentration was maximal (from 58.9 to 379.5 micrograms/ml) at the first or second sampling time (2 to 10 h after administration). Thereafter, both MP and MPA declined rapidly. From time of administration to about five days later, MP synovial fluid concentration fell progressively with a half-time of 9.95 h. Subsequently, the MP synovial fluid concentration decreased more slowly with an apparent half-time of 115 h. During the first 24 h following MPA administration, trace amounts of MP (less than 5 ng/ml) were detected in plasma. Plasma hydrocortisone levels were depressed for three to four days after administration but adrenal responsiveness to adrenocorticotrophic hormone tests remained unaffected.

Adrenal Glands↗

PubMedDate not supplied

Exaggerated femoral anteversion and acetabular development: experimental study in growing dogs.

Femoral excessive anteversion caused by femoral osteotomy in growing dogs is an accurate dynamic model of experimental acetabular dysplasia. Radiographic and CT scan examinations were performed throughout the growing period. Evolution showed an incomplete femoral detorsion. It induced acetabular developmental modification leading to an anterior and superior acetabular dysplasia. At the end of the growing period, hips were not dislocated, but signs of femoral and acetabular osteoarthritis were obvious, which shows the importance of mechanical force modification in the creation of experimental osteoarthritis. The links between hip osteoarthritis and exaggerated femoral anteversion are discussed. Might acetabular dysplasia be secondary to femoral anteversion, which could justify a corrective osteotomy during childhood? Our experiment leads to a better comprehension of this phenomenon.

Acetabulum↗