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Biomedical subjects

M D Tilson

Publications and source records attributed to M D Tilson.

At least 19 recordsLinked to original sources
PubMed1992

Characterization of an elastase from aneurysmal aorta which degrades intact aortic elastin.

Accumulating evidence suggests that abdominal aortic aneurysms (AAA) are due to a pathologic process which results in the destruction of aortic elastin and other matrix components. In this study, protein extractions were performed on both aneurysmal and normal aorta. Extracts were applied to frozen section of normal aorta either alone or in combination with 10 mM ethylenediaminetetraacetic acid, recombinant tissue inhibitor of metalloproteases, 10 mM zinc, and 5 mM phenylmethylsulfonyl fluoride, under conditions where calcium was removed from the buffer. After incubation, the sections were stained for elastin and evaluated by computerized morphometry. Aneurysm extracts, only in the presence of calcium, showed significant elastolytic activity characterized by destruction of intact elastic lamellae that was inhibited by ethylenediaminetetraacetic acid, the recombinant metalloprotease inhibitor, and zinc. Phenylmethylsulfonyl fluoride showed no inhibitory activity. Healthy aortic extract showed no elastolytic activity. This inhibitory profile is consistent with a metalloenzyme. We conclude that aneurysmal aorta contains elastolytic activity that is secondary to a metalloenzyme which is not present in normal aorta. This activity may play a role in the destruction of the elastin matrix that is seen in AAA's.

Aorta, Abdominal↗
PubMed1991

The role of inflammation in nonspecific abdominal aortic aneurysm disease.

The predominant pathologic feature of abdominal aortic aneurysm is elastin destruction, and elastin destruction may be mediated by inflammation. In this investigation serial sections of abdominal aortic aneurysm specimens were selectively stained to study the relationship between inflammation and elastin degradation. In addition, soluble aortic extracts were examined for the presence of immunoglobulins. An inflammatory infiltrate was present in 8 of 10 of the abdominal aortic aneurysm specimens examined. The infiltrate was mononuclear, commonly located at the junction of the media and adventitia; it did not codistribute with loss of elastin. The presence of an inflammatory component in abdominal aortic aneurysm was associated with a large amount of immunoglobulin in soluble extracts from aneurysmal tissue compared to atherosclerotic and normal control extracts. This study further characterizes the microscopic pathology of abdominal aortic aneurysm and describes the presence of immunoglobulin in soluble tissue extracts. In addition, the possible role of inflammation in abdominal aortic aneurysm as it relates to protease expression is detailed.

Aorta, Abdominal↗
PubMed1991

Decreased tissue inhibitor of metalloproteinases (TIMP) in abdominal aortic aneurysm tissue: a preliminary report.

Important concepts underlying the pathophysiology of abdominal aortic aneurysm (AAA) disease include a genetic predisposition, male predominance, and increased proteolysis. Proteolytic activity is carefully controlled by an abundance of protease inhibitors and the increased proteolysis may reflect a decrease in inhibitory activity. The recent assignment for the major tissue inhibitor of metalloproteinases (TIMP) to the X chromosome provides a potential link between the male predominance and increased proteolysis noted in AAA. The purpose of this investigation was to measure the amount of TIMP in normal and diseased aorta. A polyclonal antibody to recombinant human TIMP was produced in rabbit and used to establish an immunoassay. Immunoreactive TIMP in normal and diseased aorta was then measured. There was more TIMP in the matrix-associated fraction than in the soluble fraction. There was significantly less immunoreactive TIMP in aortic extracts from AAA than from control as measured both by Western blot and radioimmunoassay. These results suggest that a diminished amount of TIMP in the aortic matrix in AAA patients may contribute to the increased proteolysis observed in AAA.

Aorta, Abdominal↗
PubMed1991

Suggested standards for reporting on arterial aneurysms. Subcommittee on Reporting Standards for Arterial Aneurysms, Ad Hoc Committee on Reporting Standards, Society for Vascular Surgery and North American Chapter, International Society for Cardiovascular Surgery.

The literature on arterial aneurysms is subject to potential misinterpretation because of inconsistencies in reporting standards. The joint councils of the Society for Vascular Surgery and the North American Chapter of the International Society for Cardiovascular Surgery appointed an ad hoc committee to address this issue. This communication, prepared in response to the need for standardized reporting, defines and classifies arterial aneurysms and recommends standards for describing the causes, manifestations, treatment, and outcome criteria that are important when publishing data on aneurysmal disease.

Aneurysm↗
PubMed1979

Obturator canal bypass grafts for septic lesions of the femoral artery.

Infection of the femoral artery results in false aneurysm formation and hemorrhage unless appropriate reconstructive measures are taken. We reviewed ten such cases managed by obturator canal bypass with autogenous saphenous vein. The graft maintained viability of the extremity in every case in the early postoperative period. One death occurred related to cardiac disease, and there was one late failure. This experience confirms the usefulness of the obturator canal as a method for bypass of the infected femoral artery.

Adolescent↗
PubMed1979

Surgical principles and polytetrafluoroethylene.

This report describes a 24-month follow-up in 100 consecutive polytetrafluoroethylene (PTFE) arterial grafts. Although initial results were superb, a continued follow-up has showed extremely high closure rates for femoropopliteal and femorotibial grafts. The primary reason for this high attrition rate is thought to be stasis. We believe that PTFE is clearly the best synthetic arterial replacement available, but the material does not approach the autogenous saphenous vein in terms of long-term patency. Therefore, in spite of its many advantages, we do not recommend the elective use of PTFE for peripheral small-vessel bypass.

Bioprosthesis↗
PubMed1979

Retroperitoneal cross pelvic bypass grafts.

An extraperitoneal retropubic cross iliac artery bypass graft is a safe alternative to an intra-abdominal aortoiliac bypass, axillofemoral bypass or subcutaneous femorofemoral bypass in the patient considered to be at high risk. This procedure may prove to be superior to subcutaneously placed grafts because the graft is less prone to trauma and infection. The circulation of the donor limb must be adequate to produce a significant increase in the rate of flow through the recipient limb. There was an early patency of the graft in 58 of 61 patients. There was patency of the graft at three years in 40 of 61 patients.

Blood Vessel Prosthesis↗
PubMed1978

Abdominal angina.

Explore the source record for details and available documents.

Aorta, Abdominal↗
PubMed1977

Quantitative bacteriology and pathology of the lung in experimental Pseudomonas pneumonia treated with positive end-expiratory pressure (PEEP).

Mechanical ventilation with positive end-expiratory pre-sure (PEEP) is widely used to treat ventilatory failure complicating pulmonary infection. The present experiment was carried out to test the hypothesis that PEEP is beneficial in an experimental model of canine pneumonia studied for 24 hours. Sixteen mongrel dogs were assigned to ventilation with either zero end-expiratory pressure (ZEEP) or 10 cm H2O PEEP. Pneumonia was induced in half of each group by intratracheal inoculation with Pseudomonas. Tissues for quantitative bacteriology and pathology were obtained at the time of death at 24 hours. Three of four infected-ZEEP dogs died before 24 hours. The geometrical mean of quantitative bacterial counts from infected-ZEEP lobes was 2.0 X 10(6) (+/-3.9) (organisms/gm of tissue), while the mean of the infected-PEEP lobes was 1.7 X 10(4) (+/-3.6) (p less than 0.05). Semiquantitative pathology scores indicated greater injury to the ZEEP-infected than to the PEEP-infected lungs. Quantitative bacteriology and microscopic evidence of parenchymal injury were positively correlated. Thus PEEP-treated animals had lower quantitative bacterial counts, less microscopic pulmonary damage, and improved survival. The advantage conferred by PEEP may be due to facilitation of local mechanisms of pulmonary defense against infection, to increased systemic resistance to sepsis, or to both.

Animals↗