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Biomedical subjects

Mark W Turrentine

Publications and source records attributed to Mark W Turrentine.

33 records · Page 2Linked to original sources
PubMed2005

p38 mitogen activated protein kinase mediates both death signaling and functional depression in the heart.

BACKGROUND: Understanding the myocardial inflammatory response to ischemia is an important part of achieving the elusive clinical goal of long-enduring myocardial protection. p38 mitogen-activated protein kinase (MAPK) has been implicated in oxidant stress-induced myocardial tumor necrosis factor production. However, it is unknown whether p38 MAPK mediates the following important events in both myocardial apoptosis and functional depression: mitogen-activated protein kinase-activated protein kinase 2, caspase-1, caspase-3, and caspase-11 activation, and tumor necrosis factor, interleukin-1beta and interleukin-6 production. METHODS: Isolated rat hearts were perfused and subjected to an ischemia-reperfusion insult, with and without preischemic infusion of 20 microM SB203580 (p38 MAPK inhibitor). Myocardial functional measurements were continuously recorded throughout the experiments. Myocardial tissue was then assessed for products of p38 MAPK activation, expression of tumor necrosis factor, interleukin-1beta and interleukin-6, and activation of caspase-1, caspase-3 and caspase-11. RESULTS: Postischemic recovery of left ventricular developed pressure, +dP/dt and -dP/dt was significantly increased by p38 MAPK inhibition (MKI) (left ventricular developed pressure: 48.4 +/- 3.87 MKI versus 32.7 +/- 4.32 mm Hg; +dP/dt: 1392.0 +/- 141.7 MKI versus 896.7 +/- 128.5 mm Hg/s; -dP/dt: -889.9 +/- 97.63 MKI versus -548.9 +/- 71.29 mmHg/s). p38 MAPK inhibition also significantly reduced ischemia-reperfusion-induced elevation of left ventricular end-diastolic pressure (82.76 +/- 4.59 MKI vs 69.95 +/- 3.55 mm Hg). p38 MKI decreased myocardial tumor necrosis factor, interleukin-1beta and interleukin-6 protein levels, and reduced active myocardial caspase-1, caspase-3 and caspase-11. CONCLUSIONS: The p38 MAPK pathway indeed mediates the following important events in myocardial apoptosis and functional depression: mitogen-activated protein kinase-activated protein kinase 2, caspase-1, caspase-3 and caspase-11 activation, and tumor necrosis factor, interleukin-1beta, interleukin-6 production after myocardial ischemia. Single site (p38 MAPK) inhibition of these events may have important therapeutic implications in myocardial protection.

Animals↗
PubMed2005

Long-term results of apical aortic conduits in children with complex left ventricular outflow tract obstruction.

BACKGROUND: Apical aortic conduits were used in children with complex left ventricular outflow tract obstruction at our institution before we adopted the Ross and Ross-Konno procedures. The early results with apical aortic conduits were quite good when we used a porcine xenograft conduit and were less satisfactory when we converted to an aortic homograft valve as the conduit valve. This report summarizes our clinical experience with apical aortic conduits in children with an emphasis on hemodynamic results, reoperation, and long-term follow-up. METHODS: Records of 28 patients (age range, 2 weeks to 19 years) who underwent insertion of apical aortic conduit between September 1979 and June 1993 were reviewed. All patients had complex multilevel left ventricular outflow tract obstruction. All were symptomatic, and 22 (79%) had had one or two previous aortic valvotomies or left ventricular outflow tract operations, or both. RESULTS: Hospital mortality was 11% (3 of 28). Twenty-five children survived the perioperative period and improved, and 21 have had one or more cardiac catheterization from 6 to 18 months (mean, 1.2 years) after the initial operation. Reduction or resolution of resting mean left ventricular-to-aortic peak gradient in the early postoperative period from 81.8 +/- 24.0 to 15.4 +/- 8.9 mm Hg was demonstrated (p < 0.001). Overall 25-year survival was 57%. Fourteen surviving patients (56%) have undergone subsequent procedures (n = 18) from 5 months to 16 years postoperatively (mean, 6.9 years) because they developed a recurrent left ventricular-to-aortic gradient of 58 +/- 28 mm Hg (p < 0.002). One patient underwent heart transplantation. All other late survivors have normal left ventricular function as determined by serial echocardiography. CONCLUSIONS: Apical aortic conduit is effective in relieving complex left ventricular outflow tract obstruction and improving left ventricular performance with acceptable short-term and midterm results, but late complications caused primarily by conduit tissue valve dysfunction are frequent in children. Since the early 1990s, the apical aortic conduit procedure has been largely replaced with the Ross or Ross-Konno procedure in our pediatric practice.

Adolescent↗
PubMed2005

Aprotinin improves kidney function and decreases tubular cell apoptosis and proapoptotic signaling after renal ischemia-reperfusion.

OBJECTIVE: The purpose of the study was to determine the effects of aprotinin on (1) renal function, (2) apoptosis and apoptotic signaling, and (3) the inflammatory response of the kidney after ischemia-reperfusion injury. METHODS: Male rats underwent a sham procedure or left renal ischemia for 1 hour. Rats were divided into three groups and received no reperfusion, reperfusion for 1 hour, or reperfusion for 24 hours. The animals undergoing ischemia received saline solution alone or aprotinin (60,000 kIU/kg). At the end of the experiment, a sample for serum creatinine was taken and the left kidney was harvested. The kidney was analyzed for expression of tumor necrosis factor alpha, interleukin 1beta, and interleukin 6 (enzyme-linked immunosorbent assay and reverse transcriptase-polymerase chain reaction) and activation of p38 mitogen-activated protein kinase, caspase 3, and caspase 8 (Western blot). The kidney was assessed for apoptosis with enzyme-linked immunosorbent assay and by terminal deoxynucleotidyl transferase biotin-deoxyuridine triphosphate nick-end labeling staining of tissue slides. RESULTS: Aprotinin significantly decreased the rise in serum creatinine and apoptosis caused by ischemia-reperfusion. Aprotinin significantly reduced interleukin 1 and 6 messenger RNA production and showed a trend toward reducing tumor necrosis factor messenger RNA production after ischemia. Aprotinin also significantly reduced caspase 8 activation and showed a trend toward decreasing p38 mitogen-activated protein kinase activation after 1 hour of reperfusion. CONCLUSION: These results suggest that aprotinin provides protection from renal ischemia-reperfusion injury. They also suggest that aprotinin may do so by affecting apoptotic signaling and inflammatory cytokine production. Aprotinin is a potential therapeutic measure in clinical situations where renal ischemia-reperfusion injury can be anticipated, provided adequate heparinization is possible.

Animals↗
PubMed2004

Reduced pericardial levels of endostatin correlate with collateral development in patients with ischemic heart disease.

OBJECTIVES: We investigated whether pericardial levels of a pro-angiogenic factor (vascular endothelial growth factor, VEGF) or an anti-angiogenic factor (endostatin) related to the presence of coronary collateral circulation in patients with significant coronary artery disease (CAD). BACKGROUND: Coronary collateralization favorably alters the prognosis of patients with occlusive CAD. The specific factors that mediate and maintain collateral formation in coronary vessel occlusion are yet to be identified. METHODS: Coronary angiograms from 39 patients undergoing coronary artery bypass surgery were evaluated for the absence of collaterals (n = 20) or the presence of Rentrop classification grade 3 collaterals (n = 19). Pericardial fluid samples were obtained at the time of surgery and were assayed for the VEGF and endostatin by enzyme-linked immunosorbent assay comparing the two groups of patients. RESULTS: Vascular endothelial growth factor levels were not significantly different between the groups (28.86 +/- 4.67 pg/ml vs. 24.39 +/- 3.08 pg/ml, p = 0.43). However, pericardial fluid endostatin levels were nearly 40% lower in patients with grade 3 collateralization compared with those lacking angiographic evidence of collaterals (15.17 +/- 1.87 ng/ml vs. 24.25 +/- 2.08 ng/ml, p < 0.0025). CONCLUSIONS: Pericardial fluid levels of endostatin, but not VEGF, are associated with the presence or absence of collaterals in patients with CAD. These data suggest that the angiogenesis inhibitor endostatin levels may locally modulate coronary collateral formation.

Aged↗
PubMed2004

Incidence, outcome, and risk factors for stroke after the Fontan procedure.

We reviewed records on patients who underwent hemi-Fontan and Fontan procedures over a 13-year period at a single institution to examine the incidence and outcome of stroke and to attempt to identify risk factors for stroke. A history of pulmonary artery banding was associated with an increased risk of stroke.

Adolescent↗
PubMed2004

Hypoxic pulmonary vasoconstriction in cardiothoracic surgery: basic mechanisms to potential therapies.

Hypoxic pulmonary vasoconstriction is postulated to be an adaptive mechanism to match lung perfusion with ventilation; however, the consequences of the maladaptive effects of pulmonary vasoconstriction represent formidable therapeutic challenges. Understanding the basic mechanisms of hypoxic pulmonary vasoconstriction will enhance the assimilation of translational research into clinical practice. The purposes of this review are to (1) define basic mechanisms of pulmonary vasoconstriction and vasorelaxation; (2) delineate the biphasic contractile response to hypoxia; (3) critically examine data that support the mediator hypothesis versus the ion channel hypothesis; and (4) explore potential mechanistic-based therapies for hypoxic pulmonary vasoconstriction.

Adaptation, Physiological↗
PubMed2004

Mitral valve replacement with the pulmonary autograft: Ross II procedure with Kabanni modification.

We report our experience with pulmonary autograft replacement of the mitral valve in eight patients. Hospital mortality of 0% was reported, and there has been one autograft failure requiring replacement (mean follow-up 12 +/- 6 months). We also review the world's experience with this technique. Mitral valve replacement with a pulmonary autograft (Ross II) is safe, reproducible, and possible warranted for selected patients.

Adolescent↗
PubMed2004

Preconditioning: evolution of basic mechanisms to potential therapeutic strategies.

Preconditioning describes the phenomenon by which a traumatic or stressful stimulus confers protection against subsequent injury. Originally recognized in dog heart subjected to ischemic challenges, preconditioning has been demonstrated in multiple species, can be induced by various stimuli, and is applicable in different organ systems. Tremendous progress has been made elucidating the signal transduction cascade of preconditioning. Preconditioning represents a potent tissue-protective condition, and mechanistic understanding may allow safe clinical application. This review recalls the history of preconditioning and how it relates to the history of the investigation of endogenous adaptation; summarizes the current mechanistic understanding of acute preconditioning; outlines the signal transduction cascade leading to the development of delayed preconditioning; discusses preconditioning in noncardiac tissue; and explores the potential of using preconditioning clinically.

Animals↗
PubMed2003

After repair, atrioventricular valve regurgitation during cardiac extracorporeal membrane oxygenation predicts survival.

BACKGROUND: When echocardiography is used to follow up cardiac patients on extracorporeal membrane oxygenation (ECMO), ejection fraction as a measure of ventricular function has been used to determine likelihood of survival after decannulation. We hypothesized that systemic atrioventricular (AV) valve regurgitation while on ECMO may be a better predictor of survival. METHODS: From February 1995 to March 2001, 64 patients required ECMO postoperatively. Three were removed from ECMO owing to brain death, so 61 patients formed our study group. Retrospective chart review was performed with systemic AV valve regurgitation and ejection fraction while on ECMO recorded from echocardiography reports. Patients alive 1 month after decannulation were considered survivors. RESULTS: There were 29 survivors (47.5%). Ejection fraction in survivors (mean 41% +/- 0.13%) was not significantly different from that of nonsurvivors (41% +/- 0.18%; p < or = 0.839) but severity of systemic AV valve regurgitation was significantly different. Only 2 survivors (6.8%) had at least moderate AV valve regurgitation compared with 17 of the 32 nonsurvivors (53%). Patients with moderate to severe regurgitation while on ECMO were less likely to survive for 1 month after decannulation, with an odds ratio of 16.63 (95% confidence interval 3.08, 89.70; p = 0.001). Also female sex increased the odds of death by a factor of 5.43 (95% confidence interval 1.45, 20.36; p = 0.012). CONCLUSIONS: Severity of systemic AV valve regurgitation on ECMO is a more reliable predictor than ejection fraction for survival at 1 month after decannulation. Patients with less than moderate AV valve regurgitation have a significantly better chance of survival.

Child↗
PubMed2003

Surgery for aortic stenosis in children: a 40-year experience.

BACKGROUND: Aortic stenosis (AS) is encountered in approximately 5% of children with heart disease. The indications for surgery and the surgical techniques for AS are well established. This report focuses on the early and long-term outcomes in children with AS over a 40-year period. METHODS: Included in this study were 508 patients ranging in ages from 1 day to 19 years, who were operated on for AS between 1960 and 2002. Eighty-one percent (414 of 508) of the patients had left ventricular outflow tract obstruction (LVOTO) at a single level: 40 supravalvar, 242 valvar (critical AS in 85 neonates and young infants and in 157 older children), and 132 subvalvar. Nineteen percent (94 of 508) of the patients had LVOTO at more than one level. Associated congenital cardiac defects were found in 32% of the patients. RESULTS: The overall hospital mortality rate was 8% (40/508) with neonates with critical AS having the highest mortality (33%). The late mortality was 4% for the entire group. Follow-up was 95% complete. The mean follow-up was 8.5 +/- 7.1 years. In the subgroup with multilevel LVOTO (n = 94), the average intraoperative peak systolic left ventricular-aortic gradient decreased from 80 to 22 mm Hg after repair but increased progressively to 74 +/- 36 mm Hg (p < 0.05) before reintervention was required. One hundred twenty-one patients (24%) underwent 151 reoperations for recurrent or residual LVOTO or aortic regurgitation. Actuarial curves predict a 20-year survival of 88% and 62% freedom from reoperation for all patients with AS. Symptomatic improvement in survivors was excellent (90% New York Heart Association class I). CONCLUSIONS: Surgical relief of LVOTO in infants and children can be accomplished with low mortality and morbidity. Neonates with critical AS have significantly higher mortality and morbidity due to their complex anatomy and their critical presentation that affects outcome. Aortic valvotomy delays valve replacement in a significant percentage of children. The Ross procedure and mechanical aortic valve replacements have had a low mortality and morbidity in our series. Valve replacement will eventually be required in most children presenting with valvar AS and multilevel LVOTO while repair of discrete subaortic stenosis and supravalvar AS may not require reoperation in most patients. Children with LVOTO should have lifetime follow-up.

Adolescent↗
PubMed2003

Surgical management of scimitar syndrome: an alternative approach.

OBJECTIVE: The scimitar syndrome is a congenital anomaly that consists in part of total or partial anomalous venous drainage of the right lung to the inferior vena cava. Surgical approaches to the scimitar syndrome have varied according to the anatomic and pathologic features presented in each case. The aim of this study was to present an alternative approach to the surgical correction of scimitar syndrome. METHODS: Nine patients with the scimitar syndrome were operated on between 1990 and 2000. They comprised 1 male and 8 female patients (mean age 11.5 +/- 17.6 years). All patients had symptoms, with recurrent pneumonia or respiratory tract infections and pulmonary/systemic flow ratios greater than 1.5:1.0. None of the patients had pulmonary hypertension or an atrial septal defect. All patients underwent repair of the anomalous scimitar vein by direct reimplantation into the left atrium without cardiopulmonary bypass. Two patients underwent concomitant resection of a right lower lobe sequestration. Follow-up was complete in all cases. RESULTS: There were no operative or late deaths, and no patients have required reoperation. At the time of follow-up (mean 55 +/- 46 months), echocardiography demonstrated a patent anastomosis in all patients without any evidence of restenosis. CONCLUSION: This clinical experience indicates that an alternative surgical approach to scimitar syndrome is direct anastomosis of the scimitar vein to the posterior aspect of the left atrium using a right thoracotomy without cardiopulmonary bypass. This procedure is safe and effective and obviates the need for long intra-atrial baffles and the use of the extracorporeal circuit.

Adult↗
PubMed2002

PTFE monocusp valve reconstruction of the right ventricular outflow tract.

BACKGROUND: Transannular patching of right ventricular outflow tract obstructive (RVOTO) defects results in pulmonary insufficiency (PI). Biologic monocusp valves (MO) can prevent acute PI but are prone to early degeneration and progressive regurgitation. Polytetrafluoroethylene (PTFE, 0.1 mm) MO leaflets demonstrated favorable characteristics in animal studies, and the technique was applied to a variety of RVOTO anomalies. METHODS: From June 1990 through June 1999, 158 patients underwent either PTFE MO RVOT reconstruction (n = 115 patients; 120 implants) or nonvalved transannular repair (TA) repairs (n = 43 patients; 5 subsequent MO implants) at our institution. Standard MO construction techniques and TA repairs were utilized. Intraoperative, postoperative, and echocardiographic data with a mean interval of 2.6 years (range 6 months to 8 years) were used in retrospective fashion to compare clinical outcomes. In addition, PTFE monocusp valves beyond 6 months postimplant underwent echocardiographic analysis of MO function and durability. RESULTS: There were 4 early (MO-3, TA-1) and no late deaths. Overall, perioperative complications were not significantly different between MO and TA groups, nor were total hospitalization days (9.1 versus 10.7, p = 0.24). However, a significant difference in intensive care unit (ICU) utilization (3.6 versus 5.8 days, p = 0.03) favored MO patients. Patients with tetralogy of Fallot (TOF) and ventricular septal defect/pulmonary atresia (VSD/PA) undergoing the MO implant demonstrated a trend toward improved survival (p = 0.08) when compared to TA repairs. Intraoperative PI was graded mild in the MO group and moderate-severe in the TA group (p = 0.003). Progressive MO regurgitation occurred (mild-moderate) but remained significantly less than the transannular patch repairs (p < 0.05). CONCLUSIONS: Utilization of a PTFE MO valve prevents short-term and significantly reduces midterm PI. It is inexpensive, easy to construct, and demonstrates no evidence of stenosis, calcification, or embolization. Despite longer cardiopulmonary bypass and ischemic times, it reduces ICU stay and, in both TOF and VSD/PA patients, decreases operative morbidity and mortality.

Adolescent↗
PubMed2002

Polytetrafluoroethylene monocusp valve technique for right ventricular outflow tract reconstruction.

Nonvalve transannular patch repair of right ventricular outflow tract obstructive (RVOTO) defects results in pulmonary insufficiency, which can contribute to early postoperative right ventricular dysfunction. In both animal and clinical studies, monocusp valves provide perioperative RVOT competence and improved right ventricular functional characteristics. In these reports, monocusp leaflet construction with 0.1-mm polytetrafluoroethylene (PTFE) appeared equal, or superior, to biologic monocusp valves. Construction of the polytetrafluoroethylene monocusp valve is an inexpensive and straightforward way to create a competent RVOT in a variety of RVOTO anomalies. Based on our clinical experience, it effectively prevents short-term and significantly reduces midterm pulmonary insufficiency without evidence of stenosis.

Animals↗
PubMed2002

Surgical repair of congenital supravalvular aortic stenosis in children.

OBJECTIVE: Supravalvular aortic stenosis (SVAS) is an uncommon congenital cardiac anomaly characterized by varying degrees of left ventricular outflow tract obstruction beginning distal to the aortic valve. METHODS: Between March 1962 and December 2000, 101 consecutive patients underwent surgical correction for congenital SVAS at Riley Children's Hospital. There were 61 male (60%) and 40 female (40%) ranging in age from 3 month to 17 years (medium age, 6.1 years). Fourteen patients (14%) had Williams syndrome. Preoperatively, 11 patients were in New York Heart Association (NYHA) functional class I, 55 in class II, 28 in class III, and seven in class IV. Of the 101 patients, 73 (72%) had localized type SVAS and 28 (28%) diffuse type SVAS. RESULTS: Those with localized SVAS were successfully treated with patch aortoplasty, whereas those with diffuse SVAS required either an apical aortic conduit or extensive endarterectomy with patch aortoplasty. The overall mean pressure gradient was reduced to 21 mmHg (P<0.001) in the early postoperative period. There were one early death (<30 days postoperatively) (1%), two (2%) late deaths, and 14 patients (14%) underwent one or two additional operation (n=17) in a follow-up period ranging from 6 months to 30 years (medium 9.4 years). Postoperatively, there were 72 patients (73%) in NYHA functional class I and 26 (27%) in class II. Overall survival including operative mortality was 98% at 10 years, 97% at 20 and at 30 years. CONCLUSION: Good surgical outcome of congenital SVAS can be achieved with the appropriate method of treatment in patients with both localized and diffuse SVAS.

Adolescent↗