Mitochondrial function during ischemic preconditioning

Background. Ischemic preconditioning (IPC) protects the myocardium from ischemia reperfusion injury. The effect of IPC on the mitochondria is not well known. However, one of the mechanisms postulated in IPC (the opening of the mitochondrial K(ATP) channels) is likely to result in changes in mitochondrial function. Therefore, the purpose of this study was to determine the effect of IPC on mitochondrial function during ischemia reperfusion. Methods. Isolated rat hearts (n = 6/group) were subjected to (1) 30 minutes of equilibration, 25 minutes of ischemia, and 30 minutes of reperfusion (RP) (control group) or (2) 10 minutes of equilibration, two-5 minute episodes of IPC (each followed by 5 minutes of re-equilibration), 25 minutes of ischemia, and 30 minutes of RP (IPC group). Left ventricular rate pressure product (RPP) was measured. At end-equilibration (end-EQ) and at end-reperfusion (end-RP) mitochondria were isolated. Mitochondrial respiratory function (state 2, 3, and 4), respiratory control index (RCI), rate of oxidative phosphorylation (ADP/Delta t), and ADP:O ratio were measured by polarography with the use of NADH- or FADH-dependent substrates. Results. IPC improved recovery of RPP at end-RP (72% +/- 5% in IPC vs 30% +/- 4% in control, P <.05). Ischemia reperfusion (IR) decreased state 3, ADP/Delta t, and RCI in both groups compared with end-EQ. IPC improved state 3 (47 +/- 3 in IPC vs 37 +/- 2 ng-atoms O/min/mg protein in control), ADP/Delta t (17 +/- 1 in IPC vs 13 +/- 1 nmol/s/mg protein in control), and RCI (3.7 +/- 0.1 in IPC vs 2.1 +/- 0.2 in control) at end-RP compared with control with the use of NADH-dependent substrate (P <.05 vs control). IPC also improved state 3 (85 +/- 6 in IPC vs 71 +/- 4 ng-atoms O/min/mg protein in control), ADP/Delta t (18 +/- 2 in IPC vs 12 +/- 1 nmol/s/mg protein in control), RCI (2 +/- 0.1 in IPC vs 1.5 +/- 0.1 in control), and ADP:O ratios (1.4 +/- 0.04 in IPC vs 1.7 +/- 0.09 in control) at end-RP compared with control with the use of FADH-dependent substrate (P <.05 vs control). Conclusions. The cardioprotective effects of IPC can be attributed at least in part to the preservation of mitochondrial function during reperfusion.     

Predicting and understanding developmental delay of children of adolescent mothers: a multidimensional approach

Divergent literatures on potential relationships among psychological, biological, and contextual factors that may contribute to mental retardation and other types of developmental delay in the children of adolescent mothers were reviewed. A linear model was proposed to describe the direct and indirect effects of learning ability, maternal health, social support, personal adjustment, cognitive readiness for parenting, and infant characteristics on adolescent parenting and child development. Because the validity of the model can be determined through the use of causal modeling (LISREL), it holds the potential for determining a unique set of risk factors that may produce developmental delay in children of adolescent mothers. These factors can serve as the targets in designing intervention programs for such mothers.     

Empathy and outcome in brief focal dynamic therapy

In an attempt to test the hypothesis that therapist empathy is an important variable in successful dynamic therapy, the authors collected outcome measures and empathy ratings in the brief focal dynamic therapy of 59 patients. There was no significant agreement among patients, therapists, and clinical supervisors when they used the same scale to rate therapist empathy for the same sessions. Only the patients' ratings correlated significantly with some of the outcome measures, and they added modest but statistically significant predictive variance on multiple regression analysis. The authors discuss the implications of these findings for the traditional mode of supervision of dynamic therapy.     

Optimal hypothermic preservation of arrested myocardium in isolated perfused rabbit hearts: a 31P NMR study

The purpose of this study was to (1) relate myocardial high-energy phosphate stores to functional recovery after ischemia and reperfusion, (2) assess the bioenergetics and functional influence of clinically relevant myocardial hypothermia, and (3) examine tissue pH as an independent indicator of postischemic recovery of function. Rabbit hearts were perfused via a modified Langendorff technique, monitored for developed pressure (DP) and left ventricular end-diastolic pressure (LVEDP) via an isovolumic left ventricular balloon catheter, and placed in a Brucker NMR magnet (4.7 tesla) to measure phosphocreatine (PCr), adenosine triphosphate (ATP), and pH. Hearts underwent 1 hour of global ischemia at 7 degrees, 17 degrees, 27 degrees and 37 degrees C initiated by one dose of K+ cardioplegia followed by 30 minutes of reperfusion. After reperfusion, DP (expressed as a percentage of preischemic control) and LVEDP (mm Hg) in 7 degrees and 17 degrees C hearts were no different (96 + 5% vs 97 +/- 3%; 5 +/- 2 mm Hg vs 6 +/- 2 mm Hg; p = NS), but were better (p less than 0.01) than 27 degree hearts (72 +/- 6%, 17 +/- 6 mm Hg) and 37 degree hearts (31 +/- 7%, 60 +/- 6 mm Hg). PCr was severely depleted in all groups. ATP was 90 +/- 7% and 87 +/- 5% of preischemic control in the 7 degree and 17 degree hearts, which was significantly better than the 68 +/- 3% and 21 +/- 3% in the 27 degree and 37 degree groups (p less than 0.01). The pH at end ischemia was 6.83, 6.89, 6.54, and 5.86 for the 7 degree, 17 degree, 27 degree, and 37 degree hearts, respectively (7 degrees vs 27 degrees or 37 degrees, p less than 0.01; 17 degrees vs 27 degrees or 37 degrees, p less than 0.01). Linear regression of DP on end-ischemic ATP (EIATP) and end-ischemic pH revealed: DP = 0.96 (EIATP) + 20 (r = 0.92) and DP = 60 (pH) -317 (r = 0.86). We conclude that (1) end-ischemic ATP predicts recovery of ventricular function, and, furthermore, there appears a threshold ATP concentration (80% of control) below which full recovery of function will not occur; (2) end-ischemic pH predicts recovery of ventricular function; (3) 7 degrees C hypothermic ischemia does not cause a clinically significant cold injury; and (4) in a single-dose crystalloid cardioplegia model, end-ischemic pH is linearly related to recovery of function (r = 0.86).     

Evaluation of the pediatric surgical patient with congenital heart disease

Children with cardiac disease who undergo noncardiac surgical procedures may encounter risks beyond those usually associated with surgical procedures. In this article, several complicating factors seen in children with heart disease are discussed, including arrhythmias, cyanosis, congestive heart failure, pulmonary hypertension, and subacute bacterial endocarditis.     

Comparison of Coronary Venous Defibrillation with Conventional Transvenous Internal Defibrillation in Man

Objective: Animal studies have shown that defibrillation in coronary veins is more effective than in the right ventricle. We aimed to assess the feasibility of placing defibrillation electrodes in the middle cardiac vein (MCV) in man and its impact on defibrillation requirements. Methods: A prospective randomised study conducted in a tertiary referral centre. 10 patients (9 male) undergoing ICD implantation (65 (12) yrs) for NASPE/BPEG indications were studied. Defibrillation thresholds (DFT) were measured, using a binary search and an external defibrillator after 10 seconds of ventricular fibrillation, for the following configurations in each patient (order of testing randomised): RV + MCV Can and RV SVC + Can. Interventions: A dual coil defibrillation electrode was placed transvenously in the right ventricle (RV) in the conventional manner. Using a guiding catheter a 3.2 Fr (67.5 mm length) electrode was placed transvenously in MCV. A test-can was placed subcutaneously in the left pectoral region. Results: Lead placement was possible in 8/10 pts. Time to perform a middle cardiac venogram and place the electrode was 21 (23) mins. No adverse events were observed. Defibrillation current was less (6.7 (2.7) A) with RV + MCV Can compared to the conventional RV SVC + Can configuration (8.9 (3.4) A, p = 0.03). There was no significant difference in defibrillation voltage or energy. However, shock impedance was higher in the former configuration (57 (10) v. 43 (6) , p = 0.001). Conclusions: In the majority of cases placement of a defibrillation lead in MCV is feasible. Defibrillation current requirements are 25% less when the shock is delivered using a MCV electrode.     

Using art to express a personal philosophy of nursing

The authors describe an innovative teaching strategy using art to express personal philosophy of nursing. This teaching strategy gives students and faculty an opportunity to be creative and to express their personal feelings about the nature of nursing.