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Biomedical subjects

M C Leeson

Publications and source records attributed to M C Leeson.

At least 19 recordsLinked to original sources
PubMed2004

Treatment of advanced metastatic lesions of the acetabulum using the saddle prosthesis.

Current methods of treating advanced patients with metastatic periacetabular disease are complex and result in high complication rates. The purpose of this study was to show whether the implantation of the saddle prosthesis would serve as an additional tool to help treat metastatic disease in these patients. From 1991 to 2003, 20 patients with advanced metastatic periacetabular lesions (Harrington Class III) were treated using the saddle prosthesis. Goals of surgery were a decrease in pain, functional restoration, and ambulation. The mean age was 61 years. Average length of followup was 20 months. Postoperatively, ambulation was achieved in 16 of 20 patients. There were four postoperative complications (20%) in three patients. Surgical goals were met in 18 of 20 patients. The MSTS-ISOLS emotional score was 2.9 of 5. The average total MSTS-ISOLS score was 16.6 of 30 (55%). Using the Allan scoring system consisting of analgesia, independence and ambulation, and mobility, all scores had significant improvements postoperatively. Careful surgical indications and technique should result in a stable, functional reconstruction allowing patients the ability to ambulate outside the house with a cane. Patients can expect to be emotionally satisfied with the procedure while using nonnarcotic analgesia and can expect an improved quality of life despite bone metastasis.

Acetabulum↗
PubMed1994

Differential antibiotic-induced release of endotoxin from gram-negative bacteria.

Treatment of log phase cultures of Escherichia coli with cell wall active antibiotics results in increased exposure of immunologically reactive lipid A epitopes of lipopolysaccharide (LPS) and release of soluble LPS into culture supernatants. Comparison of the efficacy of two cell wall active antibiotics, ceftazidime, a penicillin-binding protein 3 selective antibiotic, and imipenem, a penicillin-binding protein 2 selective antibiotic, for their relative efficacy in mediating LPS release indicated quantitative but not qualitative differences, with the former antibiotic manifesting a significantly broader range of concentrations at which LPS release could be demonstrated. Comparison of the relative efficacy of these two antibiotics in a mouse bacteraemia model in which animals were made hypersensitive to the lethal effects of endotoxin by treatment with D-galactosamine indicated that the latter antibiotic may provide a greater level of protection. These studies suggest that the release of endotoxin mediated by antibiotic treatment may contribute to the pathogenesis of disease in infectious due to gram-negative organisms.

Animals↗
PubMed1994

Induction of proinflammatory responses in human monocytes by particulate and soluble forms of lipopolysaccharide.

Lipopolysaccharide (LPS), a major constituent of the outer membrane of Gram-negative bacteria, is thought to be chiefly responsible for induction by these organisms of Gram-negative septic shock, an often fatal complication of Gram-negative septicemia. Accordingly, monocytes and macrophages, which are believed to be the primary cellular targets of LPS, have been shown to mount vigorous proinflammatory responses to highly purified, soluble LPS. Relatively less is known, however, about the ability of these cells to respond to native, insoluble forms of LPS, such as those represented by intact Gram-negative bacterial particles. Furthermore, the intact microbe would be expected to exhibit additional non-LPS components that are capable of stimulating proinflammatory responses, and the relative roles of these components and LPS in stimulating proinflammatory responses have not, to date, been fully defined. Therefore, experiments have been conducted to assess stimulation of human monocytes by highly purified, soluble LPS as well as by particulate forms of LPS, including Gram-negative bacterial particles and LPS-coated latex beads. As indicated by induction of procoagulant activity and production of tumor necrosis factor, LPS appears to be the Gram-negative bacterial component of primary importance for induction of monocytic proinflammatory responses. Furthermore, the presentation of LPS associated with the bacterial surface is also capable of eliciting such responses, albeit with less potency than that observed for soluble LPS. At least part of this reduction in potency appears attributable to the particulate nature of bacterium-bound LPS, since a reduction in potency is similarly observed for soluble LPS coated onto latex beads.

Animals↗
PubMed1994

Evidence for lipopolysaccharide as the predominant proinflammatory mediator in supernatants of antibiotic-treated bacteria.

Lipopolysaccharide (LPS), purified from gram-negative bacteria, is well known to induce proinflammatory responses in monocytes and macrophages, and release of LPS from the microbial surface has been suggested to be an important initiating event in the sepsis syndrome. However, numerous studies have documented that a variety of constituents present in the outer cell membrane of gram-negative bacteria have the capacity to activate cells of the immune system. Given that the majority of immunotherapeutic approaches designed to intervene in gram-negative sepsis have to date targeted the LPS molecule, it would be of value to assess the relative proinflammatory properties of LPS and other gram-negative structures. Experiments were therefore undertaken to assess stimulation of human monocytes by components released from Escherichia coli following bacteriolysis by the cell wall-active antibiotic ceftazidime. As assessed by both induction of procoagulant activity and release of tumor necrosis factor, bacterial culture supernatants contain significant proinflammatory activity. When culture supernatants are fractionated via either velocity sedimentation in sucrose gradients or isopycnic density gradient ultracentrifugation in cesium chloride, the predominant monocyte-stimulating activity is identified in LPS-containing fractions. Further, such activity can be readily abrogated by the addition of polymyxin B. These results provide support for the hypothesis that LPS may be responsible for the majority of the proinflammatory activity released from E. coli following bacteriolysis in vitro.

Antigens, Bacterial↗
PubMed1993

Metastatic carcinoma of the spine with neurologic complications: an autopsy review.

We conducted post-mortem examinations on 12 patients who had documented metastatic carcinoma to the spine with attendant neurologic complications. The examinations were studied to determine the location of the metastatic lesion in relation to the spinal cord. Both gross and microscopic examinations were performed, with particular attention to the level of compression. The majority of the metastatic tumors involved the vertebral body and pedicles anterior to the spinal cord. The findings of this autopsy review support previous surgical findings, and re-emphasize the importance of considering tumor location before treating compression of the spinal cord secondary to metastatic carcinoma.

Adult↗
PubMed1993

Thermal aspects of the use of polymethylmethacrylate in large metaphyseal defects in bone. A clinical review and laboratory study.

The potential necrotizing effects of the heat produced by the exothermic polymerization process has raised questions regarding the use of polymethylmethacrylate (PMMA) in orthopedic surgery. An experimental model was used to: (1) analyze the amplitude and distribution of heat in bone taken from autopsy specimens when large metaphyseal defects (simulating tumor excision) were filled with curing PMMA and (2) to observe any significant necrotizing temperatures. The experimental design included two experimental groups of five distal femora into which either a small- or large-bore defect was made in the lateral epicondylar region. These defects were filled with either one or two packs of PMMA cement, and temperature probes were used to record temperature elevations at the cement core, the bone-cement interface, and the surrounding 1-, 2-, 3-, and 5-mm bone intervals. To simulate physiologic temperature and fluid environment, the experiment was conducted in a 37 degrees normal saline bath. There is clinical evidence suggesting that the large amounts of PMMA used in tumor reconstructive surgery (often two packs or more) may lead to thermal necrosis of remaining tumor cells in the curetted cavity. This may explain, at least in part, the decrease in recurrence of giant-cell bone tumor after curettage and PMMA cementation.

Bone Neoplasms↗
PubMed1993

Soft-tissue myxomas and fibrous dysplasia of bone. A case report and review of the literature.

An association between fibrous dysplasia and myxomas (soft-tissue neoplasms of mesenchymal origin) has been described in the literature. The authors report another such case of fibrous dysplasia/myxoma coexistence: a patient with polyostotic fibrous dysplasia who developed right anterior thigh pain from a solitary intramuscular myxoma. After a thorough review of the literature, the authors found that a causal relationship between fibrous dysplasia and myxomata remains uncertain. To ensure an adequate and accurate diagnosis, however, patients with soft-tissue myxomas should be thoroughly evaluated for fibrous dysplasia. A proper investigation of soft-tissue masses also should be carried out to exclude malignancy.

Adult↗
PubMed1990

Anaphylactic shock associated with chymopapain skin test. A case report and review of the literature.

The allergic response to chymopapain intradiscal therapy has been well documented. The most serious of these reactions is anaphylactic shock, which may result in death. Various screening methods, including skin tests, have been proposed to identify susceptible patients. Anaphylactic shock occurred in a 40-year-old woman from application of the screening skin test. Appropriate therapeutic intervention should be readily accessible when this test is performed.

Adult↗
PubMed1990

Leiomyosarcoma of the popliteal artery. A report of two cases.

Leiomyosarcomas (LS) are relatively uncommon soft-tissue sarcomas that occasionally involve the extremities. LS are usually tumors of adults and most often involve the gastrointestinal tract and uterus. When a soft-tissue sarcoma is suspected, comprehensive preoperative staging studies are an important part of the diagnostic and therapeutic management. With the use of computed tomography and magnetic resonance image scanning, the role of the arteriogram in the staging of soft-tissue tumors has been markedly diminished. There is still, however, a place for the arteriogram in the staging of soft-tissue tumors that are proximate to or displace the neurovascular bundle. Two patients demonstrated LS that arose from the popliteal artery, illustrating the importance of arteriography. When indentation and displacement can be visualized, involvement of the artery should be suspected. This may be critical when considering limb salvage versus amputation surgery. If limb salvage surgery is to be accomplished, an interpositional graft and segmental resection of the artery are necessary.

Aged↗
PubMed1989

Ewing's sarcoma of the foot.

Ewing's sarcoma is a rare, malignant neoplasm that is most common in children and adolescents. It is common in both the axial and appendicular skeleton but has been rarely reported in the foot. Historically, treatment has consisted of chemotherapy and radiation therapy. The roll of surgery in the management of these lesions have recently been "rediscovered" and depends on the anatomic location. The purpose of this paper is to discuss five consecutive cases of Ewing's Sarcoma of the forefoot treated with below-the-knee amputation for local tumor control. Four of the five patients also underwent some systemic chemotherapy. After comparing the various forms of therapy for this tumor, the benefits of below-the-knee amputation make it an excellent primary treatment for Ewing's sarcoma of the foot.

Adolescent↗
PubMed1989

The use of radioisotope scans in the evaluation of primary lymphoma of bone.

Primary lymphoma of bone is a rare lesion comprising less than 5% of all malignant primary bone tumors. Because of this rarity, the diagnosis of this lesion based on clinical findings and standard radiographic evaluations is extremely difficult and may not be entertained until after a biopsy has been performed. We retrospectively reviewed the cases of 22 consecutive patients with a diagnosis of primary lymphoma of bone (appendicular and axial skeleton) who along with standard radiographic evaluations had a technetium 99 bone scan performed as part of the preoperative staging process. A characteristic pattern demonstrating an increased uptake of intense tracer concentration peripherally and a relatively cold central area was seen consistently in all cases. This uptake pattern is then reversed with use of a gallium 67 scan. Because of the ambiguity of plain radiographs in the evaluation of adult bone lesions, radioisotope bone scans should be used as a diagnostic aid in an attempt to obtain as much information as possible about the biologic behavior of the bony lesion prior to any surgical intervention.

Adolescent↗
PubMed1989

Ganglioneuroma of the sacrum.

Ganglioneuromas (GNs) are benign, slow-growing, rare soft-tissue tumors that arise from the sympathetic nervous system and comprise less than 1% of all soft-tissue neoplasms. Although GNs are slow-growing, they can and will invade bone and pressure local adjacent structures by their continued growth. In a 20-year-old woman, GN produced a large presacral mass. This case illustrates the diagnostic features at various stages of growth, histopathology, and treatment of GN.

Adult↗
PubMed1989

Intramedullary fixation of unstable distal radius fractures. A method of fixation allowing early motion.

During a four-year period, we have treated unstable fractures of the distal radius with closed anatomic reduction and insertion of a Rush intramedullary rod through a small dorsoradial wrist incision, followed by early controlled range of motion. In an attempt to reduce the stiffness commonly seen in the fingers, wrist, and elbow, a simple method of more stable fixation and early motion was instituted. Patient assessment using common anatomic and functional classification systems revealed good to excellent results in 35 of 36 patients (98%). Only three patients had complications, and these were all minor in nature. Three rods were removed, all because of prominence and irritation of the tip of the rod over the radial styloid. The procedure is technically reproducible, and has a very high rate of patient acceptance and satisfaction.

Adult↗
PubMed1988

Aneurysmal bone cyst of the distal thumb phalanx. A case report and review of the literature.

Although aneurysmal bone cysts are a well-known, well described clinical entity, their presence in small bones of the hand are not a common occurrence. Only 13 previous cases involving the bones of the hand have been reported in the English literature. Of these 13, only seven involved the phalanges and no previous case has been described involving the distal phalanx of the thumb. Because these lesions may demonstrate aggressive local biologic behavior, when the diagnosis of aneurysmal bone cyst of the small bones of the hand is considered, prompt diagnostic and therapeutic intervention should be performed. Early recognition and management of this lesion is essential to prevent amputation.

Adolescent↗
PubMed1988

Extensive hemosiderin deposition in the medial meniscus of a knee. Its possible relationship to degenerative joint disease.

Hemosiderin deposition in the tissues of the musculoskeletal system is unusual, and deposition of these pigments in the menisci of the knee is extremely rare. Conditions that may predispose to these changes include rheumatoid arthritis, hemochromatosis, pigmented villonodular synovitis, hemophilia, and tuberculous arthritis. A 79-year-old woman developed extensive hemosiderin deposition in the medial meniscus of a knee. Hemosiderin within meniscal chondrocytes was associated with degenerative joint disease and suggested a cause and effect relationship.

Aged↗