Effect of systemic inhibition of prostaglandin synthesis on muscle protein balance after trauma in the rat

Myositis Ossificans of Rectus Femoris: A Rare Case Report

Introduction:

Myositis ossificans (MO), heterotopic ossification, occurs in muscles and soft tissue. This lesion contains actively proliferating fibroblasts and osteoblasts. It commonly affects vigorous young men and more so among athletes. It occurs as a result of trauma, either acute or chronic and can also arise near joints in neurological disorders. By time of presentation, ossification is extensive and the benign nature of the lesion is usually evident on radiological studies. Most common muscles involved in MO are the flexor muscles of the arm, the hamstrings and quadriceps femoris.

Case Report:

We present a case of MO with isolated involvement of rectus femoris in mid-thigh and sparing of other three muscles of quadriceps femoris, with no improvement following physiotherapy and medical management requiring surgical excision for better prognosis with no recurrence.

Conclusion:

MO, a benign lesion, is known to affect the flexors of the arm, the hamstrings, and quadriceps femoris; it must be noted that even individual muscle can also be affected as shown in the above case presentation without involving whole group of muscles. Surgical excision is indicated if non-operative measures are not successful.

Bilateral deltoid myositis ossificans in a weightlifter using anabolic steroids

A 40-year-old male weightlifter presented with a 6-month history of a painless mass in the right deltoid. He had no history of trauma to the shoulder other than an arthroscopic rotator cuff repair a few weeks earlier. Physical examination showed a firm, nontender mass located longitudinally and coinciding with the deltoid, measuring 12×14×4 cm. There was no limitation in range of motion or functioning. Magnetic resonance imaging (MRI) and computed tomography (CT) scans suggested a lobulated, heterogeneous mass with multiple areas of calcification that raised suspicion for soft tissue sarcoma vs myositis ossificans. Marginal resection of the soft tissue mass was performed, and pathologic studies confirmed the diagnosis of xanthogranulomatous myositis ossificans with dystrophic calcifications and central cystic degeneration. At 2-week follow-up, the patient had improved range of motion and pain, but he noted a second soft tissue mass in the left deltoid. The MRI and CT scans showed a 10.5×16×3.4-cm linear, lobulated lesion with multiple calcifications, similar in appearance to the contralateral deltoid. The patient admitted to frequently injecting anabolic steroids into his deltoids. Because the patient was asymptomatic on the left side and the MRI appearance of the left deltoid mass was similar to that of the myositis ossificans seen on the right side, the patient opted for nonsurgical treatment. This is a rare case of myositis ossificans occurring bilaterally in the deltoids after repeated injections of anabolic steroids. There is currently no known association between anabolic steroids and myositis ossificans. This condition often mimics malignant neoplasms, illustrating the necessity of resection for diagnostic confirmation.

Traumatic myositis ossificans as a result of college fraternity hazing

We present a case of a 20-year-old college student who had myositis ossificans traumatica develop after a fraternity hazing. The patient was struck repeatedly on both of his thighs while standing at attention, and he presented with bilateral thigh pain and stiffness 6 weeks after the incident. Physical examination revealed 130 degrees flexion of his right knee and 50 degrees flexion of his left knee, which had a firm end point. Radiographs showed extensive new bone located adjacent to the anterior and lateral aspects of his left femur with less involvement of his right thigh. Magnetic resonance imaging revealed considerable edema involving much of the rectus femoris and vastus lateralis of both thighs. The patient was treated with physical therapy and indomethacin for pain and inflammation control. At his 1.5-year followup, the patient's left knee flexion had improved to 130 degrees . Nonoperative treatment with careful followup resulted in a favorable outcome in this patient despite considerable formation of bilateral thigh myositis ossificans traumatica.

Prostaglandin E and prostacyclin receptor expression in tumor and host tissues from MCG 101-bearing mice: a model with prostanoid-related cachexia

Preclinical and clinical studies in our laboratory have suggested that prostaglandin (PG) E2 is involved in anorexia and cachexia development, although the role of COX pathways on the pathogenesis of cancer cachexia remains to be clarified. Expressions of PGE (EP1, EP2, EP3alpha,beta,gamma and EP4) and PGI (IP) receptors in the central nervous system (brain cortex, hypothalamus and brain stem), in peripheral (liver, white adipose tissue and skeletal muscle) and tumor tissue from MCG-101-bearing mice with and without indomethacin treatment were investigated by RT-PCR and immunohistochemistry. Expression of EP1 in the liver and EP4 receptor in white adipose tissue were upregulated and responded to indomethacin treatment, while downregulated expression of EP3 in skeletal muscle from tumor-bearing mice was unresponsive to indomethacin treatment despite improved carcass weight. Expression of EP and IP receptors in brain and tumor tissue from tumor-bearing mice were neither related nor responsive to systemic PGE2 levels including increased IL-1beta, IL-6 and TNF-alpha host activities. The expression IP receptor in CNS, peripheral tissue and tumor tissue was unchanged by cachexia development. Our results suggest that transcription of EP receptors in liver, fat and skeletal muscle tissue may be a control level for host metabolic alterations during tumor progression, while overall EP and IP receptor expression in CNS did not indicate an important control level for appetite regulation in MCG 101-bearing mice despite prostanoid related anorexia.

Influence of a standardized closed soft tissue trauma on resistance to local infection. An experimental study in rats

PURPOSE

The etiology of local posttraumatic infection in the locomotor system depends on the amount, virulence and pathogenicity of the inoculated microorganisms and the local/systemic host damage due to the type and extent of the accident or iatrogenic trauma. The relative effect of these factors remains unclear. In particular, it is still unclear today whether--in presence of microorganisms--soft tissue damage and its pathophysiological consequences lead to infection after soft tissue trauma, or whether the bacterial contamination is the primarily cause for posttraumatic infection. The aim of the project was to gain information on the consequences of a soft tissue injury in terms of resistance to local infection. Since clinical populations are too heterogeneous, the problem was investigated in a standardized, reduced (no surgery or implants) experimental in vivo model.

METHOD

In female Sprague-Dawley-rats with a standardized closed soft tissue trauma to the tibialis anterior muscle (group I: n=13) or without (group II: n=13), we compared the incidence of local infection after a pairwise local, percutaneously injected bacterial challenge with various concentrations of Staphylococcus aureus (2 x 10(4)-2 x 10(6) colony forming units, CFU). The standardized closed soft tissue trauma was created by application of a specially designed, computer controlled impact device. The contaminated soft tissue and the underlying bone were removed under sterile conditions after five days and quantitatively evaluated for bacterial growths. Infection was defined as positive bacterial growth at the soft tissue and/or bone. A stepwise experimental design with an "up-and-down" dosage technique was used to adjust the bacterial challenge in the area of the ID50 (50% infection dose). Statistical evaluation of the difference between the infection rates of both groups was performed by two-sided fisher exact test (p<0.05).

RESULTS

The overall infection rate was 46%. For the group with soft tissue trauma the ID50 was 1.32 x 10(5) CFU and 1.05 x 10(6) CFU for the group without soft tissue trauma. The infection rate was 69% (9 of 13 animals) for the group with soft tissue trauma and 23% (3 of 13 animals) for the group without soft tissue trauma. This difference is statistically significant (p=0.047).

CONCLUSIONS

The infection rate after a standardized closed soft tissue injury was significantly higher and the ID50 lower than without soft tissue trauma. Our results demonstrate that in presence of microorganisms it is not primarily the bacterial contamination but rather the soft tissue damage and its pathophysiological consequences resulting in decreased infection resistance that secondarily lead to infection.

Muscle contusion injury and myositis ossificans traumatica

In athletic competition, muscle contusion injury is a frequent and debilitating condition. Found in traditional contact and noncontact sports, contusions also can occur to the nonathlete by simple falls and accidents. The injury consists of a well-defined sequence of events involving microscopic rupture and damage to muscle cells, macroscopic defects in muscle bellies, infiltrative bleeding, and inflammation. The repair of the tissue can be thought of as a race between remodeling and scar formation. In the current study, the authors describe the relevant body of research directed at delineating the incidence, factors that affect injury severity, and treatment of muscle contusion injury. Emphasis is given to animal models that allow reproducible, quantitative injury, and study of the effects of various treatment modalities. Myositis ossificans traumatica, one of the most debilitating consequences of contusion injuries, also is discussed. The incidence, causative factors, and prevention strategies are reviewed.

Muscle contusion injuries: current treatment options

Muscle contusion is second only to strain as the leading cause of morbidity from sports-related injuries. Severity depends on the site of impact, the activation status of the muscles involved, the age of the patient, and the presence of fatigue. The diagnosis has traditionally been one of clinical judgment; however, newer modalities, including ultrasonography, magnetic resonance imaging, and spectroscopy, are becoming increasingly important in both identifying and delineating the extent of injury. Although controlled clinical studies are scarce, animal research into muscle contusions has allowed the description of the natural healing process, which involves a complex balance between muscle repair, regeneration, and scar-tissue formation. Studies are being performed to evaluate the effects of anti-inflammatory medications, corticosteroids, operative repair, and exercise protocols. Prevention and treatment of complications such as myositis ossificans have also been stressed, but recognition may improve the outcome of these ubiquitous injuries.

In vivo analysis of microcirculation following closed soft tissue injury

Major loss of tissue is an almost invariable consequence of severe closed soft-tissue injury. Clinically, the extent of soft-tissue trauma determines the outcome of complex injuries and significantly influences bone healing. With use of a new animal model, this study quantitatively analyzed microcirculation, i.e., nutritive perfusion and leukocyte-endothelial cell interaction, in skeletal muscle after standardized closed soft-tissue injury. By means of a computer-assisted controlled-impact technique, a severe standardized closed soft-tissue injury was induced in the left hindlimb of 28 rats. The rats were assigned to four experimental groups (n = 7 per group) that differed by time of analysis (1.5, 24, 72, and 120 hours after injury); rats that were not injured served as controls (n = 7). Intramuscular pressure was measured, and microcirculation in the rat extensor digitorum longus muscle was analyzed by in vivo fluorescence microscopy, which allowed assessment of microvascular diameters, functional capillary density, number of rolling and adherent leukocytes in venules, and microvascular permeability. Edema weight gain was quantified by the ratio of wet to dry weight of the extensor digitorum longus muscle. Microvascular perfusion of the skeletal muscle was characterized by a significant reduction in functional capillary density, which was paralleled by an increase in capillary diameter throughout the 120 hours of observation when compared with the controls. Trauma-induced inflammatory response was reflected by a markedly increased rolling and adherence of leukocytes, primarily restricted to the endothelium of postcapillary venules; this was accompanied by increased microvascular permeability, indicative of a substantial loss of endothelial integrity. The microcirculation surrounding the core of the damaged tissue area resembled that of ischemia-reperfusion injury in skeletal muscle, i.e., heterogeneous capillary perfusion, pronounced microvascular leakage, and adherence of leukocytes. Enhanced vascular leakage and leukocyte adherence (24-72 hours after injury) coincided with the maximum intramuscular pressure (which was not indicative of compartment syndrome) and edema formation. These results demonstrate that initial changes, leading to ultimate tissue death, after closed soft-tissue injury are caused on the microcirculatory level. This standardized model provides further insight into microvascular pathophysiology and cellular interactions following closed soft-tissue injury. Thus, it is an adequate tool for testing novel therapeutic interventions.

The effect of anabolic steroids and corticosteroids on healing of muscle contusion injury

The effect of an anabolic steroid (nandrolone decanoate, 20 mg/kg) and a corticosteroid (methylprednisolone acetate, 25 mg/kg) on healing muscle injured with a drop-mass technique in a reproducible muscle contusion injury model in the rat was studied. Healing was determined by measuring active contractile tension in each muscle and histologic analysis. At day 2, the corticosteroid group showed significant improvement in both twitch and tetanic strength relative to the controls. At day 7, this effect was reversed and the corticosteroid muscles were significantly weaker than the control muscles, but there was still no significant effect seen in the anabolic steroid group. At day 14, the corticosteroid muscles were totally degenerated, with disorganized muscle fiber architecture. The anabolic steroid muscles were significantly stronger in twitch, and a similar trend was seen in tetanus relative to control muscles. The results indicate that in an animal model corticosteroids may be beneficial in the short term, but they cause irreversible damage to healing muscle in the long term, including disordered fiber structure and a marked diminution in force-generating capacity. Anabolic steroids may aid in the healing of muscle contusion injury to speed the recovery of force-generating capacity. Although anabolic steroids are considered renegade drugs, they may have an ethical clinical application to aid healing in severe muscle contusion injury, and their use in the treatment of muscle injuries warrants further research.

Involvement of prostaglandins in cachexia induced by T-cell leukemia in the rat

We have previously demonstrated that experimentally induced T-cell leukemia in the rat results in a rapid and severe cachexia. This weight loss is largely due to a reduction in food intake, but is also accompanied by inappropriately high rates of energy expenditure. Increases in resting oxygen consumption (VO2) of 25% to 35% above the levels of pair-fed animals were observed over the period of weight loss. The present study investigated the possible involvement of prostaglandins in the cachexia induced by T-cell leukemia in the rat. Acute systemic injection of the cyclo-oxygenase inhibitors (indomethacin 1 mg/kg or flurbiprofen 1 mg/kg intraperitoneally [IP]) significantly reduced (by 14% and 10%, respectively) the increase in metabolic rate and also reversed the elevated body temperature of leukemic animals. Intracerebroventricular (ICV) injection of indomethacin (0.2 mg/kg) had only modest effects on the increase in temperature or hypermetabolism of leukemic animals. Long-term daily injection of indomethacin or flurbiprofen (1 mg/kg/d IP) had no significant effect on food intake or body weight of leukemic animals, and neither treatment significantly affected disease status. Indomethacin significantly reduced the decline in epididymal fat pad weight of leukemic animals. These data indicate that prostaglandins, produced peripherally, are involved in the acute hypermetabolism associated with T-cell leukemia, but have little or no effect on the hypophagia or body weight loss of leukemic rats.

A muscle contusion injury model. Biomechanics, physiology, and histology

We developed a reproducible muscle contusion injury and studied its effect on contractile function, histology, and passive failure. An instrumented drop-mass technique (mass, 171 g; height, 102 cm; spherical radius, 6.4 mm) delivered a single impact to the posterior surface of the gastrocnemius muscle in one limb of 40 male Wistar rats. On Day 0, the impact significantly (N = 12, P < 0.01) decreased maximum tetanic tension to 63% of the contralateral control value. Histologic examination demonstrated extravasation of erythrocytes, edema, myofiber disruption, and vacuolation of myofibers. Passive failure initiated at the site of injury. At 2 days, tetanic tension was 75% of controls (N = 11, P < 0.01). Histologically, acute inflammation and phagocytosis were noted. Tetanic tension at 7 days was 81% of controls (N = 8, P < 0.01). Vimentin staining indicated a dramatic increase in myoblast activity. Contractile strength was near normal at 24 days. Histologic examination showed complete regeneration of normal striated muscle fibers. No vimentin activity was found. No passive failures initiated at the injury site. Contusion injury produced a significant deficit in contractile function that continually diminished with gross histologic evidence of degeneration, regeneration, and normalization at the injured muscle fibers.

Dietary omega 3 fatty acid alters prostaglandin synthesis, glucose transport and protein turnover in skeletal muscle of healthy and diabetic rats

The present study was designed to determine if dietary-fat-induced alterations in the fatty acid composition of skeletal-muscle lipid alters insulin-dependent and basal muscle metabolism, including glucose and amino acid transport, prostaglandin (PG) synthesis and protein turnover. Rats were fed on high-fat semi-purified diets providing 19% or 1% omega 3 fatty acids in the form of fish oil, for 6 weeks. After 3 weeks, half of the rats were made diabetic by a single injection of streptozotocin (50 mg/kg body wt.). After a further 3 weeks, contralateral epitrochlearis and extensor digitorum longus (EDL) muscles from each rat were incubated in vitro. High levels of dietary omega 3 fatty acids decreased PGE2 and PGF2 alpha synthesis in EDL and epitrochlearis muscle (P less than 0.0001). Diabetes and insulin had no effect on PG synthesis. Diet did not alter basal glucose or amino acid transport in EDL muscle from healthy or diabetic rats. Insulin increased glucose and amino acid transport (P less than 0.0001); the increase in glucose transport by insulin was significantly greater in muscles of rats fed on high levels of omega 3 fatty acids (P less than 0.05). Epitrochlearis from rats fed on high levels of omega 3 fatty acids showed decreased net protein degradation in the presence and absence of insulin, owing to decreased rates of protein degradation and synthesis. The data suggest that high levels of dietary omega 3 fatty acids that alter muscle membrane composition also result in alterations in glucose transport and the metabolism of muscle protein.