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Biomedical subjects

M Spira

Publications and source records attributed to M Spira.

At least 19 recordsLinked to original sources

A new vascularized nerve graft model in the rabbit.

The macro- and microanatomy of the rabbit median nerve were studied for the purpose of developing a vascularized nerve graft (VNG) model. A segment of median nerve was then designed as a vascularized graft to serve as a model. This model consists of a 1-cm long median nerve segment and its accompanying brachial artery and vein 3 cm in length, with an arteriovenous fistula created distally. The model was tested by using the VNG to repair an intratemporal facial nerve defect and proven to be reliable. Its monofascicular pattern and diameter match those of the reconstructed facial nerve, making this model unique, compared to other models previously described.

Animals

Reconstruction of calvarial defects.

We subdivide the calvarium into three zones, each with its special reconstructive requirements. Based on our experience with calvarial defects in 13 patients, we favor use of autogenous material, especially in the face of previous infection or a scarred recipient bed. Alloplasts give excellent forehead contour but alloplastic reconstruction should be delayed for 1 year after injury. Vascularized bone grafts maintain contour well. They are best suited to large periorbital defects. At other locations we favor split calvarial free bone grafts. Occasionally, the defect may be so large as to warrant grafts from multiple donor sites. Use of vascularized muscle helps eradicate infection, provides a vascularized bed for free bone grafts, and fills dead space. The frontal sinus is managed either by cranialization (if the posterior wall is involved) or by mucosal stripping with obliteration of the nasofrontal duct. Additional technical considerations include rigid bone fixation, surgical exposure through a bicoronal incision, and meticulous handling of bone grafts.

Adolescent

A new flap model in the rat.

Standardized skin flap models in the rat, such as the McFarlane and Finseth flaps, have suggested placement on the rat of only a single flap. The single flap, because of variations in skin vasculature among rats, may be problematic and require prohibitively large numbers of rats to obtain statistically significant results. In this study of 60 Sprague-Dawley rats, we have developed a flap model designed to be paired in a single rat and standardized to serve as the experimental flap and the control. At the level of the symphysis pubis, symmetrical, three-sided, caudally based, bilateral skin flaps, 2 cm in width, were extended to different bony landmarks. Only the length of the flaps was varied. The inferior epigastric pedicle was then divided. The flap length, which optimally produced predictable and persistent necrosis, was found midway between the xiphoid and the sternal notch. The model was pharmacologically manipulated with the injection of superoxide dismutase through the epigastric vein before division of the inferior epigastric pedicle; this scavenger did not effect the survival of the random pattern flaps.

Animals

The trauma of suction-assisted lipectomy cannula on flap circulation in rats.

The effect of suction-assisted lipectomy on cutaneous blood vessels of inguinal skin flaps was studied and compared in 191 rats. Different types of cannula tips were used; the number of passes was standardized. In one experiment, following suctioning, 3 X 2 cm groin island flaps based on inferior epigastric pedicles were raised and then reattached. Fluorescein dye study and microangiography were performed to evaluate flap viability. Flap survival was determined clinically and by histologic examination on the fifth postoperative day. Three-sided inguinal random-pattern flaps were raised in a second experiment and reattached following suctioning. On the fifth postoperative day, surviving flap areas were measured using standard photographs and an imaging computer and were compared with controls. Results showed that cannula passes accompanied by vacuum are harmful to vessels, while those unaccompanied by vacuum are not. The greater the number of suctioning passes, the more trauma there is to vessels and the greater is the likelihood of flap necrosis. Conical and spatula tips were more harmful to vessels than spherical, cobra, keel cobra, or Fournier tips. These results support the conclusion that suction-assisted lipectomy enhances the possibility of skin necrosis by traumatizing the vascular pedicle of a flap, especially when it is used as an adjunct to flap elevation.

Animals

Evaluation of anastomotic techniques in the experimental transfer of free skin flaps.

Vascularized groin flaps were transferred to the contralateral side by various microvascular anastomotic techniques. There was no statistical difference between the results of end-to-end and end-to-side anastomoses, when the same sized vessels were compared. However, significant differences existed when vessels smaller than 0.5 mm in diameter were anastomosed.

Animals

Experimental esophageal reconstruction in rats, with a free groin flap.

The reconstruction of a functioning esophagus with a free groin flap was performed successfully in 10 rats. A technique is described for the experimental anastomosis of vessels with a diameter of 0.5 mm or less. We also describe a modification of a method to convert a hairy flap before transfer into a hairless one.

Animals

A safe anesthetic for rabbits, using methoxyflurane.

Methoxyflurane was given by inhalation as the sole anesthetic agent to 42 New Zealand white rabbits, with no mortality. The depth of respiration as well as the changes in the color of the ears were monitored constantly. A technique for administering methoxyflurane without intubation is described.

Anesthesia, Inhalation