Persistent and transient hepatitis B virus (HBV) infections in children born to HBV-infected mothers despite active and passive vaccination

Combined passive and active immunization for newborns very effectively prevents perinatal hepatitis B virus (HBV) infections. In the Netherlands, babies born to hepatitis B surface antigen (HBsAg)-positive women receive passive immunization with hepatitis B and at least three active HBsAg vaccinations. Serological testing for the presence of HBV markers was offered for all infants born to HBsAg-positive mothers between January 2003 and July 2007, after completion of their vaccination schedule. About 75% of the infants (n = 1743) completed their HB-vaccination schedule and participated in the serologic evaluation. Twelve of them (0.7%) were found to be HBV infected. Furthermore, we identified three older children with high levels of anti-HBc, anti-HBs and anti-HBe, while they were HBsAg and HBV DNA negative. This serologic profile is evidence for a resolved HBV infection. In the group of older children (1.5-5 years of age, n = 728), about half of the HBV-infected children (3 of 7) had already cleared their infection at the time of sampling. For a proper evaluation of the efficacy of a new intervention programme to prevent vertical HBV transmission, it is also important to analyse the HBV markers in serum collected when the children are older than 1.5 years. In a programmatic setting, all children born to HBV-infected mothers should be tested not only for the level of anti-HBs but also for the absence of HBsAg, because 2 of the 12 HBV-infected children (17%) had a high level of anti-HBs.

Evolutionary game theory in growing populations

Existing theoretical models of evolution focus on the relative fitness advantages of different mutants in a population while the dynamic behavior of the population size is mostly left unconsidered. We present here a generic stochastic model which combines the growth dynamics of the population and its internal evolution. Our model thereby accounts for the fact that both evolutionary and growth dynamics are based on individual reproduction events and hence are highly coupled and stochastic in nature. We exemplify our approach by studying the dilemma of cooperation in growing populations and show that genuinely stochastic events can ease the dilemma by leading to a transient but robust increase in cooperation.

Entropy production of cyclic population dynamics

Entropy serves as a central observable in equilibrium thermodynamics. However, many biological and ecological systems operate far from thermal equilibrium. Here we show that entropy production can characterize the behavior of such nonequilibrium systems. To this end we calculate the entropy production for a population model that displays nonequilibrium behavior resulting from cyclic competition. At a critical point the dynamics exhibits a transition from large, limit-cycle-like oscillations to small, erratic oscillations. We show that the entropy production peaks very close to the critical point and tends to zero upon deviating from it. We further provide analytical methods for computing the entropy production which agree excellently with numerical simulations.

Octogenarians undergoing combined aortic valve replacement and myocardial revascularization: perioperative mortality and medium-term survival

OBJECTIVE

Aim of the study was to answer the question whether the mortality and morbidity of octogenarians undergoing combined aortic valve replacement and myocardial revascularization (AVR + CABG) is higher than that of younger patients.

PATIENTS AND METHODS

Between 01/1995 and 12/2002, 242 patients underwent AVR + CABG in our institution. 37 patients were older than 80 years (16 male, 21 female, median pressure gradient over the aortic valve: 53 mmHg, median EF: 62%), 205 patients were younger than 80 years (133 male, 72 female, median gradient 48 mmHg, median EF: 61%). NYHA class, aortic valve area and valve calcification were worse in the 80+ group. Biological valve prostheses were implanted in 94.6% of the older and in 45.4% of the younger patients (p < 0.001).

RESULTS

Perioperative complications occurred more often (p = 0.0188) in the 80+ group (86.5% experienced 1 or more complications) than in the 80- group (66.3%). Similarly, the MACE (Major Adverse Cardiovascular Events) rate was higher (p = 0.0448) in the 80+ group than in the 80- group. Bleeding occurred (p = 0.092) more often in younger (9.3%) than in older (0%) patients, while renal insufficiency was more frequent (p = 0.0164) in older (21.6%) than in younger patients (7.8 %). The 30-day mortality was higher (p = 0.0045) in older (21.6%) than in younger patients (5.8%). Multivariate analysis revealed an odds ratio for early death of 2.9 (CI 1.014-8.397) for patients older than 80 years. The late death rate within the first 5 years after surgery was comparable in both groups (80- group 24.4%, 80+ group 24.3%). Postoperative quality of life was significantly worse in the 80+ group in 4 out of 8 functions.

CONCLUSIONS

Octogenarians undergoing AVR + CABG have a relatively high perioperative complication rate and mortality, but show a stable medium-term survival. The perioperative complication rate is higher in older than in younger patients, and the postoperative quality of life with regard to bodily functions is acceptable but significantly worse than that of younger patients.

[Quality standards in intensive care of cardiac surgery]

The quality of ICU treatment is very important with regard to the outcome of patients requiring prolonged ICU stay following cardiac surgery. We conducted an internal quality survey and observed a one-year survival rate of almost 75 % after protracted ICU stay. In order to optimize the quality we identified pulmonary hypertension and prolonged mechanical ventilation as predictors for an adverse outcome. According to our findings the risk for a prolonged postoperative course is higher in patients with impaired renal function and in patients undergoing complex procedures. In these patients preoperative right heart catheterization should be performed without exception. If treatment of high pulmonary resistance leads to a benefit in terms of survival should be a matter of future investigations. There are several causes which may lead to prolonged mechanical ventilation and most of them can hardly be affected. It is known that the application of CPB impairs the respiratory function. Own studies demonstrated that the utilization of a minimized CPB does not lead to shorter ventilation times. Since there is no promising approach to reduce ventilation time by standardized means, early extubation remains the main measure. It is a long and stony way to implement quality standards on the basis of quality surveys. Finding an effective approach to optimize quality is often difficult. However, discouragement has to be avoided at al costs, since the continuous endeavor after quality and improvement of quality are basic requirements of medical progress.