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Biomedical subjects

H Bouayad

Publications and source records attributed to H Bouayad.

6 recordsLinked to original sources

Temporary threshold and loudness shifts: frequency patterns and correlations.

Two experiments studied the frequency pattern of TLS (temporary loudness shift) as a function of the level and frequency of the fatiguing sound. In experiment 1, the fatiguing tones were intermittent 375-, 1500-, or 3000-Hz tones (10 s on/10 s off) at 75, 80, 85, 90, or 95 dB SPL. The TLS patterns were established for a continuous, 60-phon test tone at different frequencies presented simultaneously with the intermittent fatiguing tone. In experiment 2, a 1000-Hz exposure tone with an intermittency of 10 s on/20 s off was used with a continuous 60-dB test tone at different frequencies. In both experiments, the total exposure duration was 60 s; TLS was measured 5 s after the exposure ended. For the lowest two exposure levels, the TLS pattern had one peak centered on the exposure frequency. As the exposure level increased, a two-peak pattern became evident, with the second peak at higher test frequencies. This finding could be interpreted as psychoacoustical evidence for the double (passive and active) mode of displacement of the basilar membrane. In experiment 2, a TTS (temporary threshold shift) measurement after exposure to a 45-min, 1000-Hz tone at 90 dB was added to the TLS sessions. The correlations between maximum TTS after a 45-min exposure and the TLS obtained after a 60-s exposure were calculated for each of the exposure levels and test frequencies used in TLS measurements. The correlation reached as high as 0.9 for TLSs measured at 1120 Hz after a 90-dB exposure; it was smaller but significant for TLSs at the exposure frequency. Despite these correlations, differences in the overall patterns of TTS and TLS suggest that they stem from two different mechanisms.

Acoustic Stimulation↗

[Orthotopic transplantation of segmental hepatic graft from living donors in the dog. Technic and results].

The authors describe new technic of non-auxiliary orthotopic transplantation of segmental liver harvested from living dogs. 32 dogs were utilized. In the donor dogs, the left medial and lateral lobes were mibilized. The left portal branch, left hepatic artery, left biliary branch and the left hepatic vein were dissected free. The segmental liver graft was perfused and cooled in-situ through the left portal vein. The recipient dogs underwent two steps total hepatectomy: First the segments I, II, III, IV and V were resected. The segments VI and VII were maintained as well as the right portal vein and the retro-hepatic inferior vena cava order to keep the splanchnic and caval flux and to avoid the spleno-cavo-jugular by-pass. The segmental liver graft was then transplanted in an orthotopic position. Termino-lateral hepatico-caval anastomosis and left porto-portal anastomosis as well as arterial and biliary reconstruction were executed. All the donors survived more than 30 days. Nine recipient dogs died during the first three post-operative days from hemorrhage (3 dogs), fibrinolysis (2 dogs), primary non function of the graft (2 dogs) and hepatic artery thrombosis (1 dog). Seven recipients survived more than 30 days.

Alanine Transaminase↗

Pheochromocytoma in dogs: 13 cases (1980-1985).

Thirteen cases of canine pheochromocytoma seen at the University of Minnesota Veterinary Teaching Hospital between 1981 and 1985 were reviewed. In 8 cases, the neoplasms were locally invasive; in the remaining cases, they were confined to the adrenal gland. Clinical signs compatible with fatal cardiovascular collapse secondary to a hypertensive or arrythmic episode were observed in 6 of 8 dogs with invasive neoplasms that died during examination or shortly thereafter. The remaining 2 dogs with invasive neoplasms had antemortem diagnoses of adrenal gland neoplasm with metastases and were euthanatized. Invasion or encroachment of the caudal vena cava in 6 dogs and encroachment of the aorta and other regional vasculature in 2 dogs were discovered at necropsy. In 5 dogs, the noninvasive pheochromocytoma was found incidentally during necropsy.

Adrenal Gland Neoplasms↗

Surgical reconstruction of partial circumferential esophageal defect in the dog.

Partial circumferential reconstruction of the cervical esophagus was evaluated in the dog. An esophageal defect 5.85 +/- 1.15 cm in length involving one-half of the circumference was repaired by direct closure (group I), using longus colli muscle patch grafts (group II), and using grafts of longus colli muscle lined with buccal mucosa (group III). The incidence of leakage, fistula formation, luminal stricture, peristalsis disturbance, lining loss, the quality of surface restoration, bursting strength, and wound healing were evaluated. No fistula formation or leakage was observed in any animal. Direct closure of the defect was easier to perform, led to less inflammatory reaction, and resulted in the highest bursting strength. However, this method was associated with luminal stricture and swallowing difficulties. The longus colli muscle patch grafts (group II) were associated with a slight to moderate luminal stricture, but had more inflammatory reaction and graft surface area contraction (62%) compared to group III. The longus colli muscle lined with buccal mucosa caused no stricture and slight surface area contraction (8%). Mucosal grafts remained viable and no lining loss was observed. Despite the loss of peristalsis at the level of the graft in 25% of the group III dogs, no clinical signs or swallowing difficulties were observed.

Animals↗

Replacement of the cervical and thoracic esophagus in dog using free jejunal autografts.

Free revascularized jejunal grafts based on a single branch of the mesenteric artery and vein were selected and used for replacement of the cervical esophagus in 20 dogs. The graft pedicle was transplanted to the left external jugular vein and the internal carotid artery using end-to-side microvascular anastomoses. The procedure was successful in all the dogs; however, five dogs had fistula formation that healed spontaneously. A similar jejunal autograft was used to replace the thoracic esophagus in 20 dogs. The recipient vessels were the internal thoracic artery and vein. Only four dogs survived. Thirteen dogs could not survive because of infection resulting from leakage of esophageal content from the esophagojejunal anastomoses into the thoracic cavity. Only two dogs had infarcted jejunal grafts. The four surviving dogs could swallow liquid and semisolid food but they never returned to solid food because of difficulties with swallowing. Graft survival was confirmed with endoscopy and arterial angiography. Narrowed jejunal graft lumen was apparent with contrast radiography and endoscopy. The jejunal grafts kept peristalsis and contracted in coordinated fashion with the proximal esophagus. At necropsy, wound healing was evaluated using bursting strength and bursting circular wall tension. Although slight adhesion and fibrosis around the grafts as well as slight inflammatory reaction around the suture material were observed, the jejunal grafts were grossly and microscopically normal. All esophagojejunal anastomoses healed and the jejunal mucosa looked normal.

Anastomosis, Surgical↗