Biomedical subjects

C C Schmidt

Publications and source records attributed to C C Schmidt.

24 records · Page 2Linked to original sources

PubMed1995

Effect of growth factors on the proliferation of fibroblasts from the medial collateral and anterior cruciate ligaments.

Growth factors have been shown to stimulate fibroblast division and thus may influence ligament healing. We analyzed the effects of individual growth factors on the proliferation of fibroblasts from the medial collateral and anterior cruciate ligaments of the rabbit in vitro in order to identify growth factors that might enhance proliferation of fibroblasts and to compare the responses of the fibroblasts from the two ligaments to these growth factors. Through measurement of the uptake of [3H]-thymidine into DNA, fibroblasts from these ligaments that had been treated with epidermal growth factor and basic fibroblast growth factor were found to proliferate nearly eight times more than control fibroblasts. Additionally, the fibroblasts of both ligaments proliferated at similar rates when exposed to platelet-derived growth factor-AA, platelet-derived growth factor-BB, basic fibroblast growth factor, insulin-like growth factor-1, and interleukin-1-alpha. However, epidermal growth factor and transforming growth factor-beta caused the fibroblasts from the medial collateral ligament to proliferate at a rate 1.3-1.4 times greater than that of fibroblasts from the anterior cruciate ligament. The reverse was true with acidic fibroblast growth factor, which stimulated the fibroblasts from the anterior cruciate ligament to proliferate at a rate 1.3-1.6 times greater than that of fibroblasts from the medial collateral ligament. This study demonstrated that growth factors can stimulate cell division in ligaments and may be effective in enhancing ligament healing but that these differences were not great enough to explain fully the clinical differences observed between healing of the medial collateral and anterior cruciate ligaments.

Animals↗

PubMed1995

Healing of the medial collateral ligament after a combined medial collateral and anterior cruciate ligament injury and reconstruction of the anterior cruciate ligament: comparison of repair and nonrepair of medial collateral ligament tears in rabbits.

The optimal treatment for a combined injury of the medial collateral and anterior cruciate ligaments is controversial, and the question remains as to whether repair of the medial collateral ligament and reconstruction of the anterior cruciate ligament improves healing of the medial collateral ligament. We compared reconstruction of the anterior cruciate ligament with and without repair of the medial collateral ligament in a rabbit model of a combined injury of these two ligaments. The anterior-posterior translation and varus-valgus rotation of the knee, the structural properties of the femur-medial collateral ligament-tibia complex, and the mechanical properties of the midsubstance of the medial collateral ligament were evaluated immediately after surgery and at 6 and 12 weeks postoperatively. Repair of the medial collateral ligament led to significantly less varus-valgus rotation of the knee than did no repair, but the anterior-posterior translation of the knees in the repair and nonrepair groups were not significantly different at any study time. At 12 weeks, the cross-sectional area and ultimate load in the repair group were 60 and 53% greater, respectively, than in the nonrepair group. Among 12 specimens that were repaired (six specimens at 6 weeks and six specimens at 12 weeks), failure occurred within the midsubstance in four (two at each time period); in all of the specimens that were not repaired, failure occurred at the tibial insertion site. There was no significant difference between the modulus of the modulus of the midsubstance in the repaired and the nonrepaired medial collateral ligaments.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1995

Effect of partial laceration on the structural properties of the canine FDP tendon: an in vitro study.

The appropriate management of partially lacerated digital flexor tendons in zone 2 is controversial. Tenorrhaphy has been advocated by some on the basis of improving tendon gliding function, whereas others have recommended foregoing tenorrhaphy because of the negative impact of repair on the tensile strength of the tendon. In light of this division, we undertook a study of the effect of varying degrees of partial laceration on the structural properties of the canine flexor digitorum profundus tendon. Lacerations up to 90% of the tendon cross-sectional area were surgically fashioned. We conclude that the structural properties of the tendon are increasingly adversely affected as laceration size increases. However, based on previous estimates of in vivo forces, even tendons with up to 60% cross-sectional area involvement may be strong enough to withstand an early active mobilization regimen. Further, we conclude that neither calipers nor naked-eye estimates provide a reliable means of assessing the extent of tendon laceration.

Animals↗

PubMed1993

Non-extensile surgical approaches for two-column acetabular fractures.

We reviewed the outcome, at a mean follow-up of 14 months, of 21 two-column fractures of the acetabulum treated by operation through one or two non-extensile approaches. Eighteen procedures resulted in reduction of the articular surfaces to within 3 mm. The blood loss and operating time when two combined non-extensile approaches were used were similar to those reported for extended acetabular approaches. The incidence of heterotopic ossification which limited joint motion was low, and the average Harris hip score was 81 points. The use of non-extensile approaches for acetabular fractures in which both columns are involved avoids iatrogenic injury to the abductors, and reduces the incidence of complications.

Acetabulum↗

PubMed1987

Choice of anesthetic alters the circulatory shock pattern as gauged by conscious rat endotoxemia.

A standardized rat endotoxin shock model was used to assess the differential effects of four commonly used anesthetics upon hemodynamics before and during endotoxin shock. Forty-nine male Sprague-Dawley rats weighing 307 +/- 4 g were divided into five groups:freely-moving conscious, enflurane (2%), isoflurane (1.4%), pentobarbital (6 mg.kg-1.h-1 i.v.), and ketamine (45 mg.kg-1.h-1 i.v.). Anesthetic doses were chosen as 1.0 MAC equivalent. Anesthetized rats were intubated and ventilated with oxygen. The right carotid artery was cannulated with a thermocouple-catheter for aortic blood pressure, heart rate, and thermodilution cardiac output measurements. The right jugular vein was cannulated for measurement of central venous pressure and for i.v. injections. Data were collected over a 30-min baseline period and for 4 h after an i.v. bolus of endotoxin (40 mg.kg-1, LD100 within 24 h). Gross small intestinal pathology was rated on a 0-4 scale. Anesthetic effects were judged in terms of significant deviations from the awake data on each parameter. Despite differing patterns, total deviations were similar for enflurane, ketamine, and pentobarbital, although the latter drug was the least preferable due to particularly high systemic vascular resistance. Significantly less hemorrhagic small intestinal pathology occurred with enflurane. Ketamine offered no advantage over the inhalation anesthetics. Among the four anesthetics tested, results were closest to the awake pattern with isoflurane anesthesia, thus making it the logical choice for hemodynamic studies in experimental shock research.

Anesthetics↗

PubMedDate not supplied

The effects of platelet-derived growth factor-BB on healing of the rabbit medial collateral ligament. An in vivo study.

We report a biologic approach to improve medial collateral ligament healing using growth factors normally expressed in healing tissue. Our previous in vitro work demonstrated that platelet-derived growth factor-BB and transforming growth factor-beta 1 promoted fibroblast proliferation and matrix synthesis, respectively. There-fore, these growth factors were used in vivo to determine whether they could improve medial collateral ligament healing, whether this effect was dose-dependent, and if combinations of growth factors could improve healing more than individual growth factors. Thirty-seven rabbits had various doses of growth factors applied to the ruptured right medial collateral ligaments using a fibrin sealant delivery vehicle. The five groups consisted of 1) two groups receiving two doses of platelet-derived growth factor-BB, 2) two groups receiving two doses of this growth factor plus transforming growth factor-beta 1, and 3) one group receiving fibrin sealant only. After sacrifice at 6 weeks, biomechanical and histologic evaluations of the healing ligament were performed. Femur-medial collateral ligament-tibia complexes of the knees given the higher dose of platelet-derived growth factor-BB had ultimate load, energy absorbed to failure, and ultimate elongation values that were 1.6, 2.4, and 1.6 times greater than the same complexes of the control group. Adding transforming growth factor-beta 1 did not lead to any further increase in the structural properties of the complex compared with treatment with platelet-derived growth factor-BB. These encouraging results suggest that use of platelet-derived growth factor-BB may improve the quality of the healing medial collateral ligament, and that it may also have a similar potential for promoting healing of other ligaments.

Analysis of Variance↗