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Biomedical subjects

K Smart

Publications and source records attributed to K Smart.

6 recordsLinked to original sources
PubMed1998

Influence of ascending versus descending balloon counterpulsation on bypass graft blood flow.

BACKGROUND: Mechanical circulatory assistance is frequently needed in postcardiotomy patients to support the failing heart. A balloon catheter called SupraCor (ABIOMED Cardiovascular, Inc, Danvers, MA) has been developed and is similar to the existing intraaortic balloon pump with the exception of placement in the ascending versus the descending thoracic aorta. This investigation compared the effects of SupraCor versus standard intraaortic balloon pump on internal mammary artery and venous conduit bypass graft blood flow. METHODS: Porcine total heart bypass was used to anastomose a jugular vein from the ascending aorta to a subsequently ligated left anterior descending coronary artery. The left internal mammary artery was then anastomosed to the jugular vein so each conduit perfused the same coronary vascular bed. An additional right heart bypass preparation allowed precise control of cardiac output and blood pressure, which were maintained constant throughout mechanical circulatory assistance. Electromagnetic flow probes measured flow through each bypass graft and the other conduit was atraumatically occluded. RESULTS: The SupraCor caused a significant increase in both internal mammary artery (+70% from 35 +/- mL/min to 56 +/- 9 mL/min; p = 0.04) and venous bypass graft blood flow (+49% from 66 +/- 12 mL/min to 95 +/- 15 mL/min; p = 0.02) when compared with controls. The intraaortic balloon pump failed to alter internal mammary artery or venous bypass graft flow. CONCLUSIONS: The results demonstrate that counterpulsation with an ascending aortic balloon significantly increases coronary bypass graft flow in both internal mammary artery and venous conduits. In contrast, counterpulsation with a descending aortic balloon did not alter coronary bypass graft flow.

Animals↗
PubMed1998

Late tamponade with mechanical circulatory support.

BACKGROUND: Circulatory support with mechanical devices often leads to bleeding and tamponade. METHODS: We report a series of three patients that required mechanical circulatory support for postcardiotomy ventricular dysfunction. RESULTS: Late tamponade occurred in each patient with different clinical presentations. Early postoperative bleeding occurred in 2 patients. There was no active bleeding in any of the 3 patients. Transesophageal echocardiography was not helpful in making the diagnosis. CONCLUSION: Late tamponade, which may be the result of hematoma with earlier bleeding, can present as dyspnea, hypoxia, or forms of hemodynamic collapse. Exploratory media sternotomy is required to definitively make the diagnosis and to evacuate the hematoma.

Aged↗
PubMed1997

The prohibitin family of mitochondrial proteins regulate replicative lifespan.

Cellular senescence is determined by multiple factors, including the genetic regulation of metabolism and responses to endogenous and exogenous stresses [1-4]. Recent studies implicate a limited number of gene products in elongating lifespan in yeast and Caenorhabditis elegans [2-4]; these include the C, elegans gene cik-1, a central regulator of metabolism [5], and yeast RAS2, which controls the response to ultraviolet irradiation and other stresses [3]. Another gene postulated to effect senescence is PHB1, the yeast homologue of prohibitin [3], a rodent gene initially identified as a potential regulator of growth arrest and tumour suppressor [6-8]. Highly conserved prohibitin homologues have been identified in mammals [9], Drosophila [10], C. elegans [9], plants [11] and yeast. A second mammalian gene, encoding BAP37, a protein with sequence similarity to prohibitin, is thought to be involved in lymphocyte function [9]. Here, we show that the nuclear-encoded mammalian prohibitin and BAP37 proteins are present in mitochondria, are co-expressed, and interact physically with each other. Deletion of the Saccharomyces cerevisiae homologues, PHB1 and PHB2, results in a decreased replicative lifespan and a defect in mitochondrial membrane potential. Our observations highlight the relationship between the metabolic efficiency of cells and the ageing process, and provide evidence for its evolutionary conservation.

Amino Acid Sequence↗
PubMed1991

Cancrum oris-like lesions.

Cancrum oris is predominantly seen in children in underdeveloped countries where widespread malnutrition, dehydration and epidemic infections are present. In the western world, it is sometimes found in immunosuppressed adults with predisposing conditions such as leukaemia and infection associated with malnutrition. Early diagnosis and an intensive therapeutic approach are the key to a favourable prognosis of noma-like necro-ulcerative lesions. The prognosis is significantly improved if the predisposing condition can be removed. Two cases are presented and the treatment is discussed.

Ampicillin↗