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Biomedical subjects

L M Vistnes

Publications and source records attributed to L M Vistnes.

At least 37 records · Page 2Linked to original sources
PubMed1983

Correction of lower eyelid ptosis in the anophthalmic orbit: a long-term follow-up.

We describe a 10-year review of 53 patients having had correction of lower eyelid ptosis using fascia lata sling suspension by the operation first described in 1973. The overall conclusion is that this continues to be a reliable procedure with a low complication rate. Four major changes relating to operative technique that create a better result are as follows: (1) the surgical correction must begin with a prosthesis that is ideal for the socket; (2) the fascial strip is narrower at 2 mm; (3) the lateral orbital rim burr hole is placed higher; and (4) the passage of the fascial strip is facilitated by the use of Wright's needle. The optimal sequence of operative procedures in the anophthalmic orbit syndrome is (1) correction of enophthalmos and superior sulcus depression, (2) correction of lower eyelid ptosis, and (3) correction of upper eyelid ptosis.

Adolescent↗
PubMed1983

Scalp as skin graft donor site: rapid reuse with synthetic adhesive moisture vapor permeable dressings.

Synthetic Adhesive Moisture vapor permeable (S.A.M.) dressings, Op-Site and Tegaderm, are compared to Fine Mesh Gauze (F.M.G.), as a dressing for split-thickness skin graft donor sites. Scalp as a donor site is compared to nonscalp donor sites. The combination of S.A.M. dressings and scalp as a donor site allows for rapid reuse of a donor site. Pain is substantially decreased and rate of healing is increased when this combination is used. The scalp, because of its availability, accessibility, excellent color match for facial grafting, and rapid healing, is recommended as a donor site.

Adhesives↗
PubMed1983

The platysma muscle. Anatomic considerations for aesthetic surgery of the anterior neck.

Our current principles for the treatment of anterior neck deformities originally evolved from cadaver dissections and clinical observations. These principles have been applied over the past seven years in nearly 100 patients. We combine as indicated submandibular lipectomy, excision of the submental fat pad, chin implantation, creation or tightening of the platysma muscular sling, and skin tightening and resection. The muscular sling is created or tightened anteriorly by approximation or imbrication of the platysma muscle in the midline. Skin is removed posteriorly, utilizing a complete or lower facelift incision. Using these techniques, we have not found posterior tightening of the platysma muscle or the creation of platysma flaps to be necessary, although we would certainly use them if other alternatives were ineffective.

Adult↗
PubMed1981

Effect of implant location on compressibility and capsule formation around miniprostheses in rats, and experimental capsule contracture.

Our study of experimental contracture in rats confirms the existence in laboratory animals of a phenomenon very much like human capsule contracture. The ultrastructural features of capsules in rats are essentially identical to those for humans and rabbits. Macrophages with silicon-containing material were present. Star-shaped myofibroblasts with extended processes appeared in contracted and noncontracted capsules. The myofibroblasts contained bundles of 60 to 80 A microfilaments with included dense bodies, convoluted nuclei, and extensive peripheral vesiculation. The myofibroblasts tended to be associated with more extensive ground substance and smaller diameter extracellular fibrils than were normal synthetic fibroblasts. The incidence of contracture was similar for implants beneath different amounts of overlying soft tissue dorsally and sternally, while compressibility and subjective softness were greater for implants beneath lesser amounts of overlying tissue. A greater mass of capsule formed beneath the heavier covering, however, suggesting that in clinical experience, cosmetically more acceptable results from submuscular prosthesis placement are probably due to a padding effect. Capsule glycosaminoglycans were primarily hyaluronic acid and dermatan sulfate. The occurrence of myofibroblasts in these capsules at a relatively late period (26 weeks) implicates myofibroblasts in the contracture mechanism, but details are still unknown. Contracture is a property of the capsule tissue; preliminary observations suggest that its occurrence is independent of species, anatomical site, surgical procedure, presence of extruded gel, presence of myofibroblasts, capsule thickness, or protein, collagen, or glycosaminoglycan composition. Cells within the capsule were geometrically asymmetrical, being extremely flattened in the plane parallel to the prosthesis surface.

Animals↗
PubMed1981

Medial approximation of the platysma muscle in the treatment of neck deformities.

The platysma muscle has become recognized as a key to the correction of deformities of the neck. We believe that the decussation of the medial fibers of the platysma muscle is critical to the support of the submental region and is a factor in the pleasing angle between the neck and the chin. The approximation of the medial borders of the platysma has been described in combination with other direct approaches to the anterior neck or with aggressive repositioning or flaps of the platysma. We have achieved pleasing results in the treatment of neck deformities in a variety of clinical situations by medial approximation of the platysma through a short submental incision without other manipulations of the platysma and without complications in 45 patients. All have been followed for more than 1 year.

Adult↗
PubMed1981

Proteolytic activity of blowfly larvae secretions in experimental burns.

Secretions of larvae of the blowfly Calliphora erythrocephala digested experimental rat skin burn eschar in vivo and in vitro when applied topically in a vanishing cream base. Debridement was characterized by de-epithelialization and digestion of dermal collagen to a subfollicular level over a 3-day period. Analytic investigation of the secretions demonstrated the presence of enzymes with activities characteristic of trypsin, leucine aminopeptidase, and carboxypeptidases A and B. These were partially characterized. There was no evidence of chymotrypsin, elastase, or collagenase. Preparation of a suitable therapeutic form could result in a preparation useful for enzymatic debridement.

Animals↗
PubMed1980

Differential response of skin and muscle in the experimental production of pressure sores.

An experimental model was developed to determine the effects of pressure on skin and muscle in animals. A pressure-time regimen that consistently produced cutaneous ulceration (100 percent) over a bony pressure point was found to produce no ulceration in skin in a location where muscle separated skin and bone. When pressure was applied to skin over a transposed muscle flap and bone, a reduction of the incidence of ulceration (69 percent) was noted, as compared to the corresponding side without a muscle flap between skin and bone (100 percent ulceration). Histologic studies of skin and muscle biopsies demonstrated epidermal breakdown, increased cellularity, and muscle fiber necrosis when cutaneous ulceration occurred. In the animals without ulceration, were normal muscle or a muscle flap was interposed between skin and bone, there were nevertheless significant areas of muscle necrosis in almost every case. Although these data support the supposition that the increased mass of muscle under skin can diffuse pressure and lessen incidence of ulceration, the extremely high incidence of muscle necrosis in response to pressure, despite absence of skin ulceration points to the possibility that muscle is an unsuitable coverage for a pressure-bearing area.

Adult↗
PubMed1979

The anatomical basis for common cosmetic anterior neck deformities.

The anatomical basis for some common anterior neck deformities, the key to which is the presence or absence of decussation of the platysma muscles at the midline, is described. A plea is made to be specific in describing these deformities, and to approach corrective surgery anatomically.

Adipose Tissue↗
PubMed1979

Experience with the Fasanella-Servat operation for ptosis of the upper eyelid.

A quick, simple, and reliable operation for the correction of mild to moderate ptosis in the presence of fair to good levator function was described by Fasanella and Servat nearly two decades ago. This operation consists of resection of the conjunctiva, tarsus, and müller's muscle using a conjunctival approach. We have performed this operation in 39 patients with good to excellent results in 38. Our criteria and experience are described.

Blepharoptosis↗
PubMed1978

A microarchitectural model of regional variations in hypodermal mobility in porcine and human skin.

In this paper, we focus on the hypodermal component of the integument and its functional contribution to properties of skin mobility. A specially designed mechanical apparatus was used to measure hypodermal extensibility in vivo of 6-mm "island" punches at selected anatomical sites in anesthetized pigs. Representative regional hypodermal force displacement curves were found to differ statistically in magnitude of acceleration, slope, and extensions at breaking point. A vertically oriented "lattice network" of hypodermal fibrous elements arranged in geometric subunits is consistently seen in sample specimens. Microarchitectural differences in network configuration, geometric unit size, fat infiltration, and intrinsic collagen fiber length can be correlated directly to the biomechanical data. These findings are corroborated by light microscopy, scanning electron microscopy, and quantitative hydroxyproline concentrations. A similar network is confirmed in human cadaver biopsies. Clinically, our data suggest that skin mobility is at least partially allowed by unfolding and stretching of the hypodermal vertical collagen network, and that regional variations in fibrous network architecture satisfy specific functional requisites (e.g., joint mobility, skin stabilization), as well as serving as an expansile retractile reservoir for the deposition and absorption of fat.

Adipose Tissue↗
PubMed1978

Orbital blowout fractures: an approach to management.

Cadaver studies and clinical evidence are presented to suggest that medial wall fractures are often concomitant with orbital floor fractures. The medial wall fractures are located in the ethmoid bone midway between the medial canthus and the lesser wing of the sphenoid. These fractures may be the etiology of late enophthalmus. The discrepancy between the high frequency of occurrence of medial wall fractures in this study and the rarity of clinical diagnosis derives from the limitations of standard radiography. Computed tomography (CT scan) is useful in delineating these fractures. The operative approach is through an incision above the medial canthus. Surgical treatment includes reduction of the herniated periorbital fat and coverage of the defect with autogenous, homologous, or alloplastic materials.

Adult↗
PubMed1978

Study of encapsulation of silicone rubber implants in animals. A foreign-body reaction.

It has long been known that the formation of a fibrous capsule around an implant is a general phenomenon in nature, an inevitable result of the tissue defense mechanism called the foreign body reaction. We have investigated this reaction in animals and find it consists of a series of interrelated processes in which the final result may vary, depending on the susceptibility of the foreign material to phagocytosis, incorporation by giant cells, or isolation by fibrosis. This susceptibility depends, in turn, on the physical and chemical properties of the implant. The process of capsule formation, as well as the structure of the final capsule, is similar in animal models and in humans--so that investigations of human encapsulation may be done in animals. The cause of abnormal induration around human breast implants is still unknown, and the question of whether normal induration in the animal model can be used to elucidate abnormal clinical induration depends on further investigation of both phenomena.

Animals↗
PubMed1978

Effects of local instillation of triamcinolone on the capsules around silicone bag-gel prostheses in animals.

"Soft" silicone bag-gel miniprostheses were implanted in 103 rats. The experimental animals had periprosthetic instillations of zero, 0.2, or 2 mg of triamcinolone acetonide at implantation. The compressibility, the architecture, and the chemical composition of the surrounding tissues were observed at 10 and at 120 days. The compressibility was also measured by mechanical means at 10 day intervals. At 120 days all capsules were similar. All the capsules gradually became firmer with time after the implantation. After 60 days, the steroid-treated capsules were very slightly more compressible (softer) than the controls. This slight difference in compressibility could not be correlated with the other changes in the capsule properties we examined. It is suggested that the structure of these capsules may be similar to that of immature scar, and that it is kept in this condition by the continued stimulus of the foreign implant.

Animals↗
PubMed1978

Experimental effects on surrounding fibrous capsule formation from placing steroid in a silicone bag-gel prosthesis before implantation.

Soft-gel miniprostheses of silicone were implanted subcutaneously into 75 male rats. Groups of prostheses were preinjected with saline, a commercial form of triamcinolone acetonide, or a suspension of crystalline triamcinolone acetonide. The softness of the prosthesis mound later was measured objectively, and the capsules surrounding the implants were analyzed by histology, SEM, and chemistry, at various intervals up to 120 days after implantation. The control implants developed a normal laminar capsule. With an incidence increasing up to 100 percent at 120 days, the steroid-treated implants were surrounded by capsules lacking an inner membrane. The inner membrane of the laminar capsule had a high protein content (relative to normal tissue) and a relatively reduced collagen content, while the diffuse capsule resulting from the TA treatment had a high protein content and a high collagen content (about the same as normal tissue). No differences were found in the softness of the mounds of the implanted prostheses. The effect of the TA treatment was explained on the basis of its collagenolytic effect, which could gradually erode the normal capsule membrane. Capsule firmness could not be related to the architecture or the protein or collagen content in our findings. We hypothesize that normal capsule firmness may be related to the amount and kind of interconnection between the loose outer zone of connective tissue and the surrounding tissue.

Animals↗