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Biomedical subjects

L M Vistnes

Publications and source records attributed to L M Vistnes.

At least 55 records · Page 3Linked to original sources
PubMed1977

Uses of RTV silicone in orbital reconstruction.

In a five-year follow-up of 42 patients with unsatisfactory cosmetic results after enulceation, room-temperature vulcanizing (RTV) silicone was used in the surgical correction of enophthalmos and superior sulcus depression. RTV silicone with a catalyst was placed in a dissected pocket subperiosteally along the floor and lateral wall of the orbit to correct the volume deficit. When vulcanizing in situ into soft silicone rubber, the implant conformed to the orbital wall and did not migrate. We determined tissue tolerance to in situ vulcanizing silicone histologically in 30 rats by inserting prevulcanized and in situ vulcanized material in paired subcutaneous pockets. No statistical difference was noted between the two methods. In 11 cases, the same material was used as a convenient stent to maintain the pressure over a graft and to maintain socket size after the reconstruction of a contrated socket, by filling the socket with RTV silicone which surrounded a Kirschner wire drilled through the lateral orbital rim.

Animals↗
PubMed1977

Grafting of Skin.

Explore the source record for details and available documents.

Bandages↗
PubMed1977

Experimental study of tissue response to ruptured gel-filled mammary prostheses.

Miniature "soft gel" filled breast prostheses were implanted into rats, and half of these were purposefully ruptured upon insertion. At sacrifice of the animals later, the position of the exuded gel, the variability of the capsule thickness, and the extent of the capsule formation were evaluated. The capsule thickness was significantly increased around the ruptured prostheses, in response to the exuded gel. Also, the gel migrated through the fibrous capsule and into the surrounding tissue, eliciting an inflammatory response there to produce capsule thickening.

Animals↗
PubMed1977

The panniculus carnosus in the domestic pig.

The panniculus carnosus arises from the superficial fascia of the midlateral back, inserts into the medial skin of the forelimb, and fuses ventrally with the contralateral cutaneous muscle. In the midback, forelimb, thigh, and groin the panniculus carnosus is lacking; there, superficial fascia alone is present. Both the panniculus carnosus and the superficial fascia divide the panniculus adiposus into a superficial compact layer and a less compact deep layer. The firm attachment of the dermis to the panniculus carnosus, and of the panniculus carnosus to the deep fascia, makes pigskin a more suitable model for comparison with human integument than the usual laboratory animals with loosely draped skin. When using the pigskin model, however, care must be exercised to define the level of incisions and the location of flaps or grafts, with respect to the panniculus carnosus.

Animals↗
PubMed1977

Excisional wound biomechanics, skin tension lines, and elastic contraction.

Confusion surrounding the concept of Langer's lines can be reduced by careful distinction among the operational definitions of the phenomenon, the empirical descriptions, and the theoretical explanations. An experimental analysis of the mechanical parameters of excisional wounds in pigskin shows that the marginal retraction, the elastic modulus at the wound midline, and the closing tension are higher for wounds oriented at right angles to tension lines--but the elastic modulus of the terminal segment of the force displacement curve is independent of orientation. The regional distribution of these values shows two patterns. The modulus parameters and the closing tension share a common distribution related to the steepness of regional force-displacement curves, while retraction has a qualitatively different distribution. On the basis of similarities in the behavior of retracting wound margins and in the distortion of punch holes which define tension lines, we hypothesize that the same mechanism may be responsible in both cases.

Animals↗
PubMed1977

Iodinated silicone-an antibacterial alloplastic material.

Iodine is readily miscible in silicones and will pass freely into and out of this material at highly predictable and constant rates. Iodinated silicone is thus an effective, controlled-rate delivery system for molecular iodine. This delivery system was shown to produce bacteriostatic and bactericidal effects in vitro, and at least bacteriostatic effects in vivo. Iodinated silicone produced a protective effect against the morbidity of infection in the mouse.

Animals↗
PubMed1976

Long-term study of reactions to various silicone breast implants in rabbits.

A long-term study of the fixation and the encapsulation of soft alloplastic implants in rabbits was done-with examination of the capsules at one, 6, 12, and 18 months. No evidence of hematoma, infection, or carcinogenesis was observed. The type of filling in the prosthesis had no demonstrable effect on the encapsulation. The mobility of the prostheses correlated directly with the capsules evoked by plain silicone, perforated silicone-backed, Dacron-backed, and polyurethane-covered prostheses (in order of decreasing mobility). A patch on the base of a given prosthesis did not influence the amount or character of the capsule formed around the remainder of that prosthesis. The results of this study are discussed in the light of past information, to point out the need for further basic research on these problems.

Animals↗
PubMed1976

Skin tension lines in the domestic pig.

The skin tension lines of the domestic pig have been mapped. With a 6mm punch biopsy, local relative skin forces can be determined. The influence of various factors (such as age, fat deposition, gascial attachments, and previous scarring) on the direction of the skin tension lines is discussed.

Animals↗
PubMed1976

The long-term effects of hard alloplastic implants when put on bone.

The resorption of bone beneath 4 alloplastic materials has been studied for periods up to 18 months in rabbit skulls. When the effects of pressure were negated, there was no significant difference in bone resorption attributable to placement above or below the periosteum. Dacron backing or polyurethane backing were associated with more inflammation and greater bone reaction than were plain silicone or stainless steel. The changes noted at 18 months were essentially the same as those noted at 6 months.

Animals↗
PubMed1976

Mechanism of upper lid ptosis in the anophthalmic orbit.

The occurrence of upper lid ptosis in 66 patients in the anophthalmic state was 18 percent, despite an adequate prosthesis. The commonly cited causes for this entity do not hold up under examination. A detailed review of the anatomy of the levator mechanism and of the anatomy of an enucleation suggests that the etiology is really based on the production of a mechanical imbalance in the levator apparatus. Suggestions for management and for the timing of the correction (in relation to other surgical procedures) are made.

Blepharoptosis↗
PubMed1976

Free grafts of autologous and homologous ureter. A functional study.

A free graft of autologous ureter will survive functionally when implanted subcutaneously whether replacing ureter or urethra, provided that the adventitia containing its longitudinal blood supply has been removed. A free graft of similarly stripped homograft ureter, although surviving initially, will eventually stenose and be rejected in the usual manner.

Animals↗
PubMed1976

Evaluation of a prototype therapeutic system for prolonged, continuous topical delivery of homosulfanilamide in the management of Pseudomonas burn wound sepsis.

The ability of homosulfanilimide (HS) delivered from two different dressing vehicles to limit bacterial proliferation was evaluated in burned animals deliberately infected with virulent Pseudomonas organisms. Treatment consisted of once daily topical application of one of two vehicles: (1) an experimental prototype system that utilized micronized HS in a hydrophobic, bioerodible, polymeric matrix, impregnated on a fabric backing; or (2) a commercially available dressing that contained the same mass of drug in a hydrophilic cream base impregnated on the same backing. Wounds on control animals were covered with fabric backing with or without the bioerodible matrix. The experimental system was designed to maintain a finite local concentration of HS on the burn wound for at least 24 hours. It is known that the cream base presents a rapidly decreasing concentration of drug to the burn surface. HS delivered from the experimental system produced a significant reduction in deaths compared with the HS delivered from the cream base. In addition, the new method of delivering HS provided better control of local and systemic infection, and better wound hydration and also promoted earlier eschar separation. The experimental system was at least as convenient to apply as the cream and had an advantage with respect to inspection of the wound, since it could be removed and reapplied easily.

Administration, Topical↗
PubMed1975

An evaluation of cryosurgery for basal cell carcinoma.

Fifteen histologically proven basal cell carcinomas were treated by conventional cryosurgery. Three to 6 months following healing, the entire treated area was excised and serially sectioned. There was clinical and microscopic evidence of residual tumor in two of the 15 cases and microscopic evidence of recurrence in one additional patient (20 percent recurrence).

Adult↗