Adenosine instead of supranormal potassium in cardioplegic solution improves cardioprotection.

OBJECTIVE: To determine whether adenosine instead of supranormal potassium in cold crystalloid cardioplegia gives satisfactory cardiac arrest and improved cardioprotection. Cold crystalloid cardioplegia with adenosine, procaine and magnesium (A) was compared with standard cold crystalloid hyperkalemic cardioplegia (K). METHODS: Sixteen pigs were randomized to receive either cold K (n=8) or A (n=8), where hyperkalemia was substituted with 1.2 mM adenosine. The cold (6 degrees C) cardioplegia was given intermittently and antegradely, with an aortic cross-clamp time of 1 h. Hemodynamic data was continuously measured and pressure-volume conductance catheters were used to determine global left ventricular systolic and diastolic function. Coronary flow and O2 content differences allowed determination of left ventricular energetics. Blood samples, and left ventricular microdialysis were used to measure parameters of ischemia. Measurements were done at 1 and 2 h after cross-clamp release. RESULTS: Mean arterial pressure was reduced with 55 mmHg (standard deviation, SD: 19) in the K group versus 30 mmHg (SD: 14) in the A group 2 h after cross-clamp release (p=0.030). Left ventricular contractility expressed as slope of the preload recruitable stroke work index (Mw) was reduced to 53% (SD: 14) in the K group versus 78% (SD: 23) in the A group 2h after cross-clamp release (p=0.046). Reduction of maximum of first derivate of pressure with respect to time (dP/dtmax) was 804 mmHg/s (SD: 189) in the K group versus 538 mmHg/s (SD: 184) in the A group (p=0.033). The slope of the myocardial oxygen consumption-pressure volume area was at 2 h reperfusion increased from 1.37 (SD: 0.64) to 2.86 (SD: 1.27) in the K group, whereas no shift was detected in the A group (p=0.019). Cardiac troponin T measured in the coronary sinus 1 h after cross-clamp release was 1.25 microg/l (SD: 0.64) in the K group versus 0.73 microg/l (SD: 0.31) in the A group (p=0.046). CONCLUSION: Adenosine instead of supranormal potassium in cold crystalloid cardioplegia gives satisfactory cardiac arrest, improves post cardioplegic left ventricular systolic function and efficiency, and attenuates myocardial cell damage.     

Mechanical restitution curves: a possible load independent assessment of contractile function.

OBJECTIVE: The time constant of mechanical restitution (T((MRC))), proposed to reflect changes in calcium release and uptake, has been shown to increase in left ventricular (LV) failure, and might have a potential as an index of contractile function. However, in vivo studies of the effect on T((MRC)) of changing loading conditions in the normal and failing heart have not been reported. Consequently, in this study, we tested the hypothesis that the increase in T((MRC)) in vivo is independent of preload and afterload. METHODS: Left ventricular pressure-volume loops were assessed at baseline in eight open chest pigs using the combined pressure-volume conductance catheter technique during right atrial pacing at 120b/min. Mechanical restitution curves (MRC) were constructed during four different loading conditions in all eight animals: uninfluenced load, reduced preload (balloon catheter in v. cava inferior), increased afterload (balloon catheter in descending aorta), and increased preload combined with reduced afterload (aortocaval shunting). Acute LV failure was then induced by microembolization through the left main coronary artery, and the experimental protocol was repeated. Contractile response was defined as the maximal first derivative of pressure (dP/dt(max)), and T((MRC)) was calculated using a least square approximation algorithm. RESULTS: Hemodynamic data 30min after microembolization showed decreased mean arterial pressure (98+/-14-67+/-10mmHg, (mean+/-SD) P<0.0001) and dP/dt(max) (1482+/-193-1001+/-125mmHg/s, P=0.001). Stroke volume decreased from 30+/-5 to 20+/-5ml (P<0.0001) compared to baseline, and preload recruitable stroke work decreased from 52+/-7 to 31+/-10mmHg (P=0.002). T((MRC)) increased in all eight animals after induction of LV failure at all loading conditions. There was no difference between the different loading conditions at baseline, nor at LV heart failure, but T((MRC)) increased significantly after the induction of heart failure (ANOVA, two ways). CONCLUSIONS: We have shown that the left ventricular T((MRC)) increases after developed heart failure. The increase in T((MRC)) was independent on loading conditions and thus have a potential for a contractility index.     

Hepatic stellate cell activation in liver transplant patients with hepatitis C recurrence and in non-transplanted patients with chronic hepatitis C.

The pathogenic mechanisms of accelerated graft fibrosis in hepatitis C recurrence after liver transplantation (LT) are not well established. The aim of the study was to assess whether a greater activation of hepatic stellate cells (HSC), the major collagen-producing cells in the liver, can occur in these patients as compared to non-LT patients with chronic hepatitis C. We determined the amount of activated HSC by computer-based morphometric analysis of alpha-smooth muscle actin (alphaSMA)-positive cells and the hepatic TGFbeta(1) expression by immunohistochemistry in 46 LT patients with hepatitis C recurrence, 35 non-LT patients with chronic hepatitis C, and 16 controls. Hepatic alphaSMA and TGFbeta(1) expression was higher in LT patients with hepatitis C recurrence than in controls and was correlated with fibrosis stage and progression rate. No significant difference in alphaSMA and TGFbeta(1) expression was observed between LT and non-LT patients with hepatitis C, with the exception of a higher transforming growth factor beta-1 (TGFbeta(1)) expression in non-LT patients in the early stages of fibrosis. LT patients receiving cyclosporine (CsA) or tacrolimus (FK) had a similar fibrosis progression rate and alphaSMA and TGFbeta(1) expression. In conclusion, the accelerated fibrosis observed in LT patients with hepatitis C recurrence does not seem to be related to a greater amount of activated HSC and TGFbeta(1) expression in the grafts of these patients as compared to non-LT patients with chronic hepatitis C. In LT patients, the amount of activated HSC and TGFbeta(1) expression correlated with fibrosis stage and progression, without any apparent influence of the type of calcineurin inhibitor administered.     

Tobacco smoking: a major risk factor for loss of teeth in three 70-year-old cohorts

Oral health was examined in a random sample of 1377 people in three 70-year-old cohorts studied within 5-yr intervals. During the studied period 1971-1983 the prevalence of toothlessness decreased from 52 to 34%. Toothlessness in men was more common in smokers, 48%, and ex-smokers, 32%, than in non-smokers, 20%. Eichner's index was used as a measurement of dental invalidity. This index showed a worse dental state among smokers and ex-smokers compared to non-smokers. Multivariate analyses indicated that tobacco smoking was a major independent risk factor for tooth loss in elderly men.     

Curriculum factors influencing knowledge of communication skills among medical students

Background  

Communication training builds on the assumption that understanding of the concepts related to professional communication facilitates the training. We know little about whether students' knowledge of clinical communication skills is affected by their attendance of communication training courses, or to what degree other elements of the clinical training or curriculum design also play a role. The aim of this study was to determine which elements of the curriculum influence acquisition of knowledge regarding clinical communication skills by medical students.     

P-fimbriae vaccines

To test for cross-protective capacity of two different P-fimbriae vaccines we vaccinated baboons with fimbriae purified from either Escherichia coli strain ER2 or strain JR1. The vaccinated animals showed elevated antibody titers to P-fimbriae from each of the E. coli strains used, suggesting cross-reactivity as was expected from the results of immunoprecipitation of the fimbriae. Enzyme-linked immunosorbent assay inhibition by heterologous P-fimbriae proved this to be true immunologic cross-reactivity.