Donald P. Speer

Identification of the depth of burn injury by collagen stainability.

Heat-denatured collagen in burned skin stains red instead of blue in Massons trichrome stain. This change in stainability corresponds to the loss of birefringence in slides examined in polarized light. The depth of the abnormal staining of the skin slices was proportional to the time and temperature of the heat exposure. It is concluded that the change in collagen stainability from blue to red relates to the loss of crystallinity or parallel alignment of the collagen fibers. It is further proposed that change in the stainability of collagen in the burns could be used to delineate the depth of the thermal skin injury or the effectiveness of the surgical excision or debridement of the wound by dressing materials.

Effect of tanning agent on tissue reaction to tissue implanted collagen sponge

Pure collagen, isolated from bovine skin, was reconstituted into the form of a sponge in the presence of either glutaraldehyde (GTA) or hexamethylene diisocyanate (DIC). Extensively washed sponges were implanted subcutaneously in rats and harvested 5 and 17 days later. Histology showed that at 5 days, the GTA-crosslinked sponge induced more cellular reaction at the outer layer of the sponge than the DIC-tanned sponge. After 17 days, the cellular infiltration of the GTA-tanned sponge remained at the periphery of the implant while the DIC-tanned sponge was completely infiltrated by inflammatory cells, including fibroblasts. Quantitative morphometry and determination of cellular DNA in sponges harvested at 17 days support the morphological finding. We conclude that GTA-tanned sponges are cytotoxic as evidenced by more pronounced tissue reaction soon after tissue implantation, and no cellular infiltration at later stages into the implant. Hexamethylene diisocyanate seems to be a more adequate tanning agent for sponges designed as a tissue substitute.

The collagenous architecture of articular cartilage. Correlation of scanning electron microscopy and polarized light microscopy observations.

The localization and directional orientation of collagen fibers in articular cartilage is demonstrated by scanning electron microscopy and polarized light microscopy. Vertical sections of articular cartilage show different directional orientations of collagen fibers through all zones of cartilage depending upon whether the sections are parallel or perpendicular to the cleft pattern produced when the surface of articular cartilage is pierced with a round pointed awl. Sections parallel to the cleft axis show a significant population of oblique collagen fibers which are not seen in sections perpendicular to the clefts. These oblique fiber groups show a progression from nearly radial to nearly tangential orientation from deep to more superficial zones, with the most abrupt directional change seen through the transitional zone. Within the transitional zone there is a narrow band having no vertical or horizontal collagen fibers and in which collagen fibers intersect predominantly at angles ranging between 45 and 135 degrees. The number of chondrocyte lacunae per unit area is greater in sections parallel to the cleft axis compared to perpendicular sections by a factor of approximately 1.6:1. There is therefore a greater relative number of chondrocytes in the plane of section having the greatest abundance of oblique collagen fibers, suggesting a cellular basis for the collagenous architecture observed. The results are consistent with published biophysical data relating tensile and swelling properties of all zones of articular cartilage to the cleft axis.

Microvascular changes in Dupuytren's contracture

Previous studies of certain fibrotic lesions (hypertrophic scar, keloid, pseudotendon) have revealed pervasive microvascular occlusion. Lowered oxygen tension is considered to be a stimulus to excessive collagen production and, hence, the scar. Because its characteristics are similar to those of other lesions, Dupuytrens contracture appeared to be a good model in which to confirm the presence of occluded microvessels. Six cases were examined by light, electron, and polarizing microscopy. Most of the microvessels from the precontracture band area throughout the periphery of the body of the nodules were occluded by a bulging of the endothelial cells into the lumen. The microvessels were surrounded by extensive layers of basal laminae. The nodules were essentially avascular. The presence of another fibrotic lesion in which pervasive microvascular occlusion occurs is suggestive of an underlying biologic principle concerning the generation of all fibrotic lesions.

The control of peritendinous adhesions using topical β-aminopropionitrile base

Abstract The Lindsay chicken foot tendon model was utilized to test the effect of topically applied β-aminopropionitrile base upon the tensile strength of peritendinous adhesions following tenolysis of a scarified flexor tendon. The agent reduced by one-third the force required to effect tendon gliding and flexion of the joints in the involved digit. The results show that topical β-aminopropionitrile is effective in the control of peritendinous adhesions and, therefore, achieves sufficient depth of penetration topically to affect the peritendinous location. No adverse effects of the topically applied agent were demonstrated. The principle of topical therapeutics that may have significant benefits to patients with tendon injuries is demonstrated.

Update on imaging and treatment of Ewing sarcoma family tumors: What the radiologist needs to know

This review article provides an update on multimodality imaging characteristics of Ewing sarcoma family tumors. Pathology of this tumor and current trends in medical and surgical treatment are briefly discussed.

Early Pathogenesis of Hemophilic Arthropathy: Evolution of the Subchondral Cyst

Observations of the knee joint made at surgical synovectomy in young children with the chronic synovitis stage of hemophilic arthropathy permitted description of the evolution of the subchondral cyst in this disease. Beginning as a subchondral hematoma beneath the load-bearing surfaces of the joint, the subchondral cyst expands, destroys bone and cartilage locally to become an osteochondral cyst, and, finally, presents as an osteochondral defect with discrete vertical margins and a depressed, sclerotic bony base. Since the thickness of articular cartilage around these osteochondral defects is well maintained, however, even weight-bearing radiographs did not reflect the extensive destruction observed at surgery. Radiographic staging of hemophilic arthropathy, while clinically useful, consistently underestimated the extent of damage to the joint surface. The pathogenesis of subchondral cysts demonstrated in the present study correlated with and explained the known radiographically observed changes of condylar flattening and intercondylar notch widening in hemophilic arthropathy.

The influence of suture technique on early wound healing

Abstract The burst strength, swelling, and microcirculatory dynamics were compared in model skin wounds closed by interrupted or continuous suturing techniques. Incised skin wounds of the midline abdomen and anteromedial and anterolateral knee of the pig were used. Microcirculatory kinetics were assessed by means of skin fluorescence following intravenous fluorescein at intervals of up to 12 days. The burst strength of wounds was measured at 12 days using an Instron Tensiometer. In wounds closed with an interrupted suture technique a 30 to 50% greater tensile strength, less edema and induration, and less impaired microcirculation at the wound margin was demonstrated in comparison to that observed in wounds closed with a continuous suture technique. The results support the use of interrupted rather than continuous suture technique for skin wound closure in instances where impaired healing can be anticipated due to disease or age, or where early stress on the healing wound is planned as in incisions about a moveable joint.

The use of large molecular weight compounds to produce local lathyrism in healing wounds

Circumferential scar surrounding healing tendons often impairs gliding function. Because mechanistic surgical approaches have been disappointing, the fundamental biology of tendon has been reviewed in search of a new approach to control circumferential scar tissue. One such approach, based upon observation that it is not formation of scar but physical properties of scar which results in loss of gliding function, is control of physical properties of newly synthesized collagen by pharmacological means. Induction of controlled lathyrism is an example of how physical properties of newly synthesized collagen can be controlled with pharmacological agents. Lathyrogenic agents provide an effective method of controlling physical properties of scar tissue in a healing wound by inhibiting formation of interand intramolecular cross-links in newly synthesized collagen [9]. Intramuscular administration of Betaaminopropionitrile (BAPN) has been shown to improve gliding function of scarified flexor tendons in the Lindsay chicken foot tendon model [ 1, 2, 61. Reversible but undesirable systemic reactions were observed, however, when BAPN was administered to human beings undergoing flexor tendon repair [6]. Because of systemic reactions which appeared to be hypersensitivity rather than toxicity, clinical investigation of BAPN was temporarily discontinued.

Directionally Guided Angiogenesis Within Extruded Type I Collagen Filaments In Vivo

Abstract Two types of crosslinked extruded type I collagen filaments were developed and characterized for implantation into canine knee joints to achieve anterior cruciate ligament (ACL) regeneration. Type A filaments were crosslinked with glutaraldehyde. Type B filaments were crosslinked with glyceraldehyde and treated with heparin and basic fibroblast growth factor (bFGF). Microscopic evaluation of the filaments revealed a gradient in the degree of crosslinking, with the surface of the filaments more highly crosslinked than the interior. The heterogeneous nature of the crosslinking was demonstrated by complementary methods using bright-field and polarized light microscopy imaging of differentially stained histological sections. In vivo, in the canine model of ACL replacement, the interior of the Type A filaments was degraded or resorbed well before the surface, thus creating collagen tubes through which new capillary channels developed. This phenomenon was not observed for the Type B collagen filaments that were degraded or resorbed from the periphery of each filament. The in vivo behavior of individual collagen filament types is correlated with the fabrication methods. The results suggest a novel method with which to achieve directionally guided angiogenesis (The J Histotechnol 29:267, 2006). Submitted October 1, 2006; accepted with revisions November 2, 2006