Wound Adhesion Research Articles

A new biodegradable matrix as part of a cell seeded skin substitute for the treatment of deep skin defects: A physico-chemical characterisation

A bilayered matrix, as an integral part of a cell seeded skin substitute for deep dermal skin injury, is described. The skin substitute has been given a dense top layer, to function as a substrate for keratinocyte culture, and a porous under layer for wound adhesion and to serve as a template for dermal regeneration. This porous under layer may be seeded with dermal fibroblasts for improvement of neodermis formation. The elastomeric hydrogel Polyactive TM a biodegradable polyether/polyester block copolymer, has been selected as the top layer component and Polyactive or Poly-L-lactide (PLLA) as the constituents of the under layer; this to ensure that the matrix is degradable and fulfils certain mechanical requirements. Polyactive top layers were found to be highly permeable to water vapour (±30 g/m −2 h −1 kPa) −1 and to molecules up to 150 kD (human IgG). Tensile properties of the bilayered matrices were to a considerable extent dependent on top layer and under layer composition and thickness. Elasticity moduli were in the range of those previously reported for human skin. Varying the weight ratios of the soft/hard segments of the Polyactives and/or substituting PLLA for Polyactive as the under layer component, allows the modulation of the matrix to specific application site dependent demands.

Increased calcium levels alter cellular and molecular events in wound healing.

Surgical morbidity is dictated directly by wound healing. We have studied the effects of elevated calcium levels using cultured keratinocytes in vitro on two of the rate-limiting steps of wound healing, chemotaxis (directed migration) and adhesion. We found that the increased calcium (10 mmol/L) significantly inhibited both keratinocyte chemotaxis and adhesion (p less than 0.05). The calcium effect on adhesion could be partially reversed by pretreatment with the calcium channel blocker verapamil. Based on these data, an animal model was formulated in which topical calcium (5 mmol/L/day) was added to linear incision wounds. This resulted in significantly (p less than 0.05) delayed wound contraction characteristic of a chronic or impaired wound. Wound contraction depends on the presence of fibroblasts that synthesize collagen. The chronic wound was characterized by increased collagenase activity (p less than 0.05) but little alteration in collagen I synthesis. The addition of verapamil to these chronic wounds resulted in improved wound closure. These studies define the molecular and cellular events occurring as a result of the addition of elevated levels of calcium both in vitro and in vivo. Calcium may play a key role in the pathogenesis of chronic wounds.

Synovectomy as treatment for purulent joint infection.

Conventional treatment of pyogenic knee joint infections leads to unsatisfactory results. Through early synovectomy, before cartilage damage and osteoarthritis appear, the infected focus can be "excised." Functional after-treatment avoids cartilage atrophy, wound adhesions, and muscle weakness. The excellent results after 26 knee joint infections confirm this.

Plastic Surgery: A Concise Guide to Clinical Practice

Two leading plastic surgeons, William C. Grabb of the University of Michigan, and James W. Smith of New York Hospital-Cornell Medical Center, have edited plastic surgery's best bargain of the year. The 43 authors are mostly drawn from the Young Turks of plastic surgery (plus a few barely middle-aged Turks), internationally known for the topics they present. Every medical student and surgical resident should read part 1, the first tenth of the book, which is a lucidly illustrated, clearly worded guide to the art of cutting, stitching, and grafting skin. Homely lessons which surgeons usually learn from experience have been put into print: catgut sutures in the oral mucosa are notorious for coming untitled—use silk; when long wounds are closed by subcuticular monofilament sutures, pass the suture through the skin every 2 or 3 inches—or suture removal will be a tussle. Recently applied tools, such as wound adhesives and microporous

Studies on the initiation of growth and moulting in Locusta migratoria migratorioides R. & F.—III. The role of the frontal ganglion

A brief review is given of some of the functions hitherto attributed to the frontal ganglion. An account is given of its gross anatomy and histology. The posterior and anterior pharyngeal nerves have been traced to the surface of the gut. The posterior pharyngeal nerves end on the anterior surface of the pharynx in two groups of three sensory organs dorso-lateral to the midline. Histologically these cells resemble the stretch receptors figured by Finlayson and Lowenstein, and this functions is provisionally accepted for them. Further studies were made on the effect of removal of the frontal ganglion at different times during the instar on the growth and moulting of the locust. Animals in which the frontal ganglion had been removed at 0, 12, and 24 hr showed a slight increase in weight and then remained constant until they died; they showed no sign of new cuticle formation at autopsy. Removal at 33 hr resulted in no increase in weight but at autopsy new cuticle formation was found under the old. The locusts did not attempt to ecdyse. Removal at 72 hr resulted in the loss of weight following the operation not being recovered, whereas at 96 hr the animals lost weight until they died some 61 hr later. In both the latter cases new cuticle under the old was found at autopsy. Those 96 hr old had made some attempt to ecdyse but they were unsuccessful due to wound adhesions. Cutting the frontal connectives had the same effect as the removal of the frontal ganglion. For unknown reasons it was always accompanied with a far higher mortality than the seemingly more severe operation of the removal of the frontal ganglion. Cutting one frontal connective had no adverse effect on the further growth and moulting of the locusts. The separation of the frontal ganglion from the surface of the foregut, which involved the cutting of the anterior and posterior pharyngeal nerves, resulted in the complete cessation of growth and moulting in the locust. Comparisons were made of the oxygen consumption of normal, starved, and frontal ganglionectomized insects. No significant difference was found between the operated and the normal locusts in oxygen consumption expressed as mm 3/mg. Starved insects showed a significant drop in oxygen consumption. In time the oxygen consumption of operated insects remained constant. It is concluded that the frontal ganglion forms a link in the passage of nervous impulses originating from the stretch receptors of the pharynx and passing via the posterior pharyngeal nerves, frontal ganglion, and frontal connectives to the brain where they may influence the medial neurosecretory cells, and possibly also via the recurrent nerve and hypocerebral ganglion to the corpora cardiaca.