Comparison of the hepatitis B virus core, surface and polymerase gene substitution rates in chronically infected patients

For phylogenetic comparison of hepatitis B virus (HBV) isolates, often a region of the HBV surface gene is analysed. Because the surface gene completely overlaps the polymerase gene, its evolution is constrained, and it may not be the best choice for genetic comparison of HBV isolates. Analysing serial sample pairs of 33 chronically HBV-infected, untreated patients, with a cumulative follow-up of 184 years, the synonymous and nonsynonymous substitution rates of a part of the overlapping HBV surface and polymerase genes were compared to those of a nonoverlapping part of the HBV core gene. The substitution rate of the HBV core gene was higher (8.15 × 10(-4) vs 4.57 × 10(-4) substitutions/site/year) than that of the surface gene. The difference was mainly due to a significantly lower synonymous substitution rate in the surface gene, with dN/dS ratios of 0.412 in the core gene and 0.986 in the surface gene. Contrary to the core gene, the number of substitutions in the surface gene was higher in low viraemic hosts, who control HBV infection by suppressing replication. The number of substitutions in the core gene correlated more strongly with the duration of follow-up. The overlapping HBV surface and polymerase genes experience strong negative selection, which limits the number of substitutions. Because the HBV core gene reflects the duration of infection more accurately, it is more suitable for the analysis of short-term viral evolution and of hepatitis B transmission chains.

Stented bioprostheses in aortic position

INTRODUCTION

Biological stented prostheses are currently the main type of prosthetic valve used for aortic valve replacement. The ratio of bioprotheses to mechanical prostheses has switched in the last 15 years; the percentage of biological  prostheses implanted has risen from 30 % to 85 %. Moreover the total number of implanted stented bioprostheses remained stable over the last years despite competing procedures like stentless prostheses or transcatheter aortic valve implantation.

METHODS

A literature search of all published aortic valve replacement studies was performed from January 2000 through May 2012.

RESULTS

The recommendations guiding the type of heart valve replacement have been revised in recent years. Of particular interest are the new generation of biological prostheses with extended durability, a decrease in mortality of reoperation and an increase in life expectancy. Comorbidities such as chronic renal insufficiency or chronic atrial fibrillation are no longer contraindications to bioprostheses.

CONCLUSION

Overall, even in face of more innovative biological alternatives the implantation of stented bioprostheses is still a very interesting option and represents actually the most frequent valve implantation technique for aortic stenosis.

aepEX monitor for the measurement of hypnotic depth in patients undergoing balanced xenon anaesthesia

BACKGROUND

Previously, we showed a significant difference in the measurements of hypnotic depth by the bispectral index (BIS) and auditory-evoked potentials (AEPs) using the A-line autoregressive index during xenon anaesthesia. In the present study, we evaluate the alternative AEP-based auditory-evoked potential index (aepEX) for the measurement of hypnotic depth in patients undergoing general anaesthesia with xenon.

METHODS

Forty-two patients undergoing elective abdominal surgery were enrolled in this controlled, double-blinded, randomized, clinical study. Patients were randomized to receive either xenon (n=21) or sevoflurane anaesthesia (n=21). During anaesthesia, BIS values were recorded simultaneously with the aepEX monitoring. The anaesthetist performing the anaesthesia was blinded to the hypnotic depth monitors. After surgery, the incidence of recalls and awareness was evaluated.

RESULTS

Patients' characteristics such as gender, age, and weight did not differ between the groups. The aepEX and BIS values behaved similarly during anaesthesia. The comparison of aepEX values during xenon and sevoflurane anaesthesia revealed significantly lower aepEX values in the xenon group after 25 min [xenon: 32.9 (4.8) vs sevoflurane: 39.3 (9.0); P=0.008] and after 35 min [xenon: 31.4 (6.6) vs sevoflurane: 37.0 (6.8); P=0.012]. During anaesthesia, aepEX values correlated with the clinical evaluation of depth of anaesthesia (e.g. >20% changes of the baseline arterial pressure or heart rate, spontaneous breathing and/or intolerance of mechanical ventilation, coughing, abdominal pressing, sweating, eye tearing).

CONCLUSIONS

We found the aepEX monitor to provide index in the range of adequate depth of xenon anaesthesia, when combined with remifentanil infusion in intubated patients undergoing elective abdominal surgery.

Randomized comparison of synchronous CABG and carotid endarterectomy vs. isolated CABG in patients with asymptomatic carotid stenosis: the CABACS trial

RATIONALE

High-grade carotid artery stenosis is present in 6-8% of patients undergoing coronary artery bypass graft surgery. Many cardiovascular surgeons advocate staged or synchronous carotid endarterectomy to reduce the high perioperative and long-term risk of stroke associated with multivessel disease. However, no randomized trial has assessed whether a combined synchronous or staged carotid endarterectomy confers any benefit compared with isolated coronary artery bypass grafting in these patients.

AIMS

The objective of this study is to compare the safety and efficacy of isolated coronary artery bypass grafting vs. synchronous coronary artery bypass grafting and carotid endarterectomy in patients with asymptomatic high-grade carotid artery stenosis.

DESIGN

Coronary Artery Bypass graft surgery in patients with Asymptomatic Carotid Stenosis (CABACS) is a randomized, controlled, open, multicenter, group sequential trial with two parallel arms and outcome adjudication by blinded observers. Patients with asymptomatic high-grade carotid stenosis scheduled for elective coronary artery bypass grafting will be assigned to either isolated coronary artery bypass grafting or synchronous coronary artery bypass grafting and carotid endarterectomy by 1 : 1 block-stratified randomization with three different stratification factors (age, gender, modified Rankin scale).

STUDY

The trial started in December 2010 aiming at recruiting 1160 patients in 25 to 30 German cardiovascular centers. The composite primary efficacy end point is the number of strokes and deaths from any cause (whatever occurs first) within 30 days after operation. A 4·5% absolute difference (4% compared to 8·5%) in the 30-day rate of the above end points can be detected with >80% power.

OUTCOMES

The results of this trial are expected to provide a basis for defining an evidence-based standard and will have a wide impact on managing this disease.

Evolutionary and population dynamics: a coupled approach

We study the interplay of population growth and evolutionary dynamics using a stochastic model based on birth and death events. In contrast to the common assumption of an independent population size, evolution can be strongly affected by population dynamics in general. Especially for fast reproducing microbes which are subject to selection, both types of dynamics are often closely intertwined. We illustrate this by considering different growth scenarios. Depending on whether microbes die or stop to reproduce (dormancy), qualitatively different behaviors emerge. For cooperating bacteria, a permanent increase of costly cooperation can occur. Even if not permanent, cooperation can still increase transiently due to demographic fluctuations. We validate our analysis via stochastic simulations and analytic calculations. In particular, we derive a condition for an increase in the level of cooperation.

[Modern coronary surgery, the SYNTAX trial and updated guidelines]

Coronary artery bypass grafting (CABG), a modern and safe procedure, is considered the therapy of choice in the care of patients with multi-vessel disease. The 3-year results of the SYNTAX trial not only showed surgical advantages in terms of repeat revascularisation, but the results also demonstrated significant surgical benefit for myocardial infarction and survival rates. More differentiated analyses showed distinct disadvantages in percutaneous coronary intervention (PCI) associated with the greater complexity of coronary pathology. PCI tends to be a comparable therapeutic option only in certain cases of left main stem lesions or multi-vessel disease. The findings from the SYNTAX study herald a new era in the treatment of coronary heart disease in which, as recommended in the updated guidelines issued by the EACTS/ESC in 2010, the interventionalist and the surgeon, working closely together as a"heart team", provide a sound therapy plan for affected patients.

Mumps epidemic in orthodox religious low-vaccination communities in the Netherlands and Canada, 2007 to 2009

We assessed the epidemiological characteristics of a mumps virus epidemic (genotype D) that occurred in the Netherlands between August 2007 and May 2009 and its association with a subsequent mumps outbreak in Canada. In the Netherlands, five data sources were used: notifications (only mandatory since the end of 2008) (56 cases), laboratory confirmation data (177 cases), a sentinel general practitioner (GP) database (275 cases), hospitalisation data (29 cases) and weekly virological reports (96 cases). The median age of cases in the notification, laboratory and GP databases ranged from 13 to 15 years. The proportion of cases that were unvaccinated ranged from 65% to 85% in the notification, laboratory and GP databases. Having orthodox Protestant beliefs was the main reason for not being vaccinated. In Canada, a mumps virus strain indistinguishable from the Dutch epidemic strain was detected between February and October 2008 in an orthodox Protestant community with historical and family links to the affected community in the Netherlands, suggesting that spread to Canada had occurred. Prevention and control of vaccine-preventable diseases among population subgroups with low vaccination coverage remains a priority.

Mumps epidemic in orthodox religious low-vaccination communities in the Netherlands and Canada, 2007 to 2009

We assessed the epidemiological characteristics of a mumps virus epidemic (genotype D) that occurred in the Netherlands between August 2007 and May 2009 and its association with a subsequent mumps outbreak in Canada. In the Netherlands, five data sources were used: notifications (only mandatory since the end of 2008) (56 cases), laboratory confirmation data (177 cases), a sentinel general practitioner (GP) database (275 cases), hospitalisation data (29 cases) and weekly virological reports (96 cases). The median age of cases in the notification, laboratory and GP databases ranged from 13 to 15 years. The proportion of cases that were unvaccinated ranged from 65% to 85% in the notification, laboratory and GP databases. Having orthodox Protestant beliefs was the main reason for not being vaccinated. In Canada, a mumps virus strain indistinguishable from the Dutch epidemic strain was detected between February and October 2008 in an orthodox Protestant community with historical and family links to the affected community in the Netherlands, suggesting that spread to Canada had occurred. Prevention and control of vaccine-preventable diseases among population subgroups with low vaccination coverage remains a priority.

[Mid-term outcome of cardiac surgery patients with prolonged postoperative intensive care treatment]

BACKGROUND

The number of patients of advanced age and with severe comorbidities undergoing cardiac surgery is rising. Therefore, in addition to the cardiac surgery procedure itself, postoperative intensive care treatment plays an increasingly important role. The mid-term outcome of patients with postoperative long-term stays in intensive care and perioperative risk factors for an adverse outcome have not been sufficiently evaluated.

MATERIAL AND METHODS

All patients who underwent cardiac surgery in our institution between 2000 and 2004 and who required intensive care treatment on our cardiac surgery intensive care unit for at least 1 week were analyzed. Patients who received heart or lung transplantation or surgery for congenital heart failure were excluded. A total of 31 perioperative variables were evaluated for 230 patients. Follow-up was performed 1 year postoperatively.

RESULTS

In all, 4.3% of our patients required a prolonged stay in intensive care following cardiac surgery. Overall 1-year mortality among patients with a long-term stay in intensive care was 26.9%. The logistic regression identified postoperative renal failure requiring dialysis (OR 4.98) as the strongest predictor for mortality within the first year after surgery, followed by postoperative tracheotomy and preoperatively known atrial fibrillation.

CONCLUSION

Mid-term survival among patients who underwent cardiac surgery followed by a complicated postoperative course is encouragingly high. The risk factors identified for an adverse prognosis may be helpful in improving therapy strategies and general therapy decision-making.

Electrophysiologic neuromonitoring during repair of the thoracoabdominal aorta by anesthesiologists

BACKGROUND

Surgical repair of the thoracoabdominal aorta is associated with risk of spinal ischemia. Electrophysiologic neuromonitoring reduces this risk, but is usually performed by neurophysiologists not always available. In this study repair of the thoracoabdominal aorta monitored by anesthesiologists has been investigated.

METHODS

Somatosensory and transcranial electrical motor evoked potentials were monitored in 20 patients. A lumbar intraspinal fluid drainage was inserted. Dacron graft replacement of the aorta was performed by sequentially clamping during partial cardiopulmonary bypass. Loss or decrease of amplitudes of evoked potentials of more than 50% prompted reinsertion of spinal arteries in the graft.

RESULTS

One patient not monitored with motor evoked potentials due to indwelling cardiac pacemaker had postoperative paraplegia. Somatosensory and motor evoked potentials were recordable in all other patients. Two patients died during surgery, one patient died postoperatively. No surviving patient monitored with somatosensory and motor evoked potentials had neurologic deficits.

CONCLUSION

Electrophysiologic neuromonitoring during surgical repair of the descending aorta can be successfully provided by anesthesiologists and should be predominately encouraged where neurophysiologists are not available due to organizational or financial shortcomings.

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.