Exploring nucleic acid condensation and release from individual parvovirus particles with different physicochemical cues.

In the infection cycle, viruses release their genome in the host cell during uncoating. Here we use a variety of physicochemical procedures to induce and monitor the in vitro uncoating of ssDNA from individual Minute Virus of Mice (MVM) particles. Our experiments revealed two pathways of genome release: i) filamentous ssDNA appearing around intact virus particles when using gradual mechanical fatigue and heating at moderate temperature (50 °C). ii) thick structures of condensed ssDNA appearing when the virus particle is disrupted by mechanical nanoindentations, denaturing agent guanidinium chloride and high temperature (70 °C). We propose that in the case of filamentous ssDNA, when the capsid integrity is conserved, the genome is externalized through one channel of the capsid pores. However, the disruption of virus particles revealed a native structure of condensed genome. The mechanical analysis of intact particles after DNA strands ejection confirm the stabilization role of ssDNA in MVM.

Everolimus for the treatment of subependymal giant cell astrocytoma probably causing seizure aggravation in a child with tuberous sclerosis complex: a case report.

We are reporting on a 13.5-year-old girl with tuberous sclerosis complex (TSC) who was treated with everolimus because of giant cell astrocytoma and bilateral angiomyolipoma. She suffered from pharmacoresistant partial epilepsy with clusters of tonic and tonic-clonic seizures. Treatment with carbamazepine and sulthiame had led to a stable situation for more than 2.5 years. The dosage of everolimus had to be increased and refractory status epilepticus followed after 12 days. In the absence of any other possible cause, we believe that the status epilepticus was provoked by everolimus. So far, only a few cases of possible seizure aggravation by everolimus have been reported. The clinical relevance of possible negative effects in epileptic patients remains unclear. Similar observations should be documented and reported.

A target-orientated algorithm for regional citrate-calcium anticoagulation in extracorporeal therapies.

BACKGROUND: Citrate anticoagulation offers several advantages in comparison to conventional anticoagulation. Most algorithms for regional citrate-calcium anticoagulation are based on citrate and calcium chloride infusion coupled in a fixed proportion to the blood flow without considering the hematocrit (Hct)/plasma flow or the filter clearance of citrate and calcium. METHODS: The aim of this study was to develop an algorithm for optimized citrate anticoagulation in extracorporeal therapies such as dialysis. A mathematical model was developed to calculate the volume of citrate infusion required to achieve a desired ionized calcium (iCa) target level in the extracorporeal circuit and to restore the total calcium level to a physiological value. RESULTS: The model was validated by correlation analyses for different blood Hct values and shows an excellent fit to the laboratory measurements. CONCLUSION: The results for both iCa target concentrations, namely those after citrate and calcium infusion, proved that the software algorithm adapts well to variable treatment parameters.

Factors influencing surgical outcome in patients with focal cortical dysplasia.

A total of 120 patients with histologically proven focal cortical dysplasias (FCD) were retrospectively analysed for prognostic factors for successful epilepsy surgery. Multivariate data analyses showed that older age at epilepsy surgery, occurrence of secondarily generalised seizures and a multilobar extent of the dysplasia were significant negative predictors. In univariate analyses, longer duration of epilepsy, need for intracranial EEG recordings and incomplete resection of the FCD were factors which significantly reduced the chance of becoming seizure free. Histological subtype of the FCD and age at epilepsy onset had no significant predictive value. These findings strongly suggest early consideration of epilepsy surgery in FCD patients.

Anticoagulation in combined membrane/adsorption systems.

For extracorporeal blood purification treatments, an effective anticoagulation is needed to avoid contact activation via the intrinsic pathway of the blood-clotting system. While heparin is the standard anticoagulant in dialysis, it shows some disadvantages which have to be considered when it is used in membrane/adsorption-based blood purification systems. An alternative option for anticoagulation in these systems is citrate, which is effective as an anticoagulant by reducing the ionized calcium concentration in the extracorporeal circuit. However, to avoid citrate accumulation in the patient during treatment, the amount of citrate infusion and the citrate removal by the patient's metabolism as well as by dialysis have to be taken into consideration. The aim of this study was to elucidate the characteristics of heparin removal in membrane/adsorption-based blood purification systems, to find the correct way to pre-coat adsorbents in order to avoid excessive adsorption of heparin by anionic exchanging resins, and also to find an appropriate dosage of heparin for treatments with these systems to ensure patient safety. A further aim was to find the correct ionized calcium concentration to suppress complement activation, and to compare different dialysis filters regarding their citrate clearance in order to be able to recommend the correct dialysis setup to achieve appropriate citrate clearance. We were able to show that the adsorptive removal of heparin can be significantly reduced by pre-coating the adsorbents with heparin without a perceptible impact on the adsorption kinetics of bilirubin. Furthermore, we recommend the use of unfractionated heparin due to its lower sieving coefficient and therefore lower removal compared to fractionated heparins. Reducing the extracorporeal Ca(2+) concentration to 0.2 mmol/L by infusion of citrate solution to the extracorporeal circuit results in an effective suppression of the complement activation. To avoid citrate accumulation, we recommend the use of high flux filters when citrate anticoagulation is applied.

Engineering of human vascular aortic tissue based on a xenogeneic starter matrix.

BACKGROUND: The goal for tissue engineering of vascular grafts is the replacement of a diseased vessel with a functional and stable graft. We now introduce a new concept for the tissue engineering of vessels. The idea was to humanize a previously acellularized, but structurally intact, xenogeneic vessel by repopulation with human autologous cells. To this purpose, a gentle nondenaturing and nondeterging acellularization procedure for xenogeneic aortas was developed. This structure was reseeded with pre-expanded peripheral vascular endothelial cells (EC) and myofibroblasts using specifically designed bioreactors. METHODS: Aortas from 15-30 kg female landrace pigs were acelullarized with a 0.1% trypsin solution for between 24 and 96 hr. Human vascular cells were harvested from saphenous vein biopsy specimens. Acellularized vessels were reseeded with EC and myofibroblasts. Cell viability after reseeding was assayed by fluorescence staining. Morphologic features of the acellularized matrix and tissue engineered vessel was assayed by transmission and scanning electron microscopy and histologic analysis. Nitric oxide-synthetase activity was investigated by mass spectrometric analysis of bioreactor supernatants. The in vivo immune response was tested by subcutaneous implantation of acellularized porcine aortic tissue in a rat model. RESULTS: The acellularization procedure resulted in an almost complete removal of the original resident cells, and the 3-D matrix was loosened at interfibrillar zones. However, the 3-D arrangement of the matrix fibers was grossly maintained. The 3-D matrix was covered with a fully confluent human endothelial cell layer obtained by continuous stress challenge in the bioreactor. Myofibroblasts migrated into positions formerly occupied by the xenogeneic cells. Nitric oxide synthetase activity was maintained in the bioartificial graft. T-lymphocyte and CD18 positive leukocyte infiltrate were greatly reduced after acellularization of porcine aortic specimens after implantation in the rat. CONCLUSIONS: Porcine vessels were acellularized and consecutively fully repopulated with human EC and myofibroblasts. This approach may eventually lead to the engineering of vessels immunologically acceptable to the host using a relatively short preparation period of 2-3 weeks. We expect matrix turnover in vivo leading to a gradual assimilation of the matrix structure by the host mediated by the hosts autologous cells.

Laser-aided debonding of orthodontic ceramic brackets.

The removal of ceramic brackets from the enamel surface by means of laser heating was investigated with the use of CO2 and YAG lasers. The two bracket types investigated were polycrystalline alumina and monocrystalline alumina. The average torque force necessary to break the adhesive between the polycrystalline ceramic brackets and the tooth was lowered by a factor of 25 when the brackets were illuminated with a CO2 laser beam of 14 watts for 2 seconds. All polycrystalline brackets debonded with the CO2 laser resulted in a complete bracket detachment without bracket failure. The average torque force needed to debond monocrystalline brackets was lowered by a factor of 5.2 when illuminated with a laser setting of 7 watts. Monocrystalline brackets cracked along the bracket slot in 2 of 10 cases. Debracketing without laser heating resulted in a slightly higher incidence of bracket failure (12 of 50). Nevertheless, no visible damage to the enamel surface was observed. Advantages of the laser-aided bracket-removal techniques include the following: The heat produced is localized and controlled; the debracketing tool is essentially "cold"; and the method can be used for removal of various types of ceramic brackets, regardless of their design.

Thin film architecture for integrated optical circuits with a nonlinear interface.

An integration architecture for optical computing can be based on the topology of an idealized nonlinear interface. Solid state multiplexing is possible with thin film multilayer stacks resulting in polarizers and phase retarders matched to the interface. Recent progress in controlling switching behavior at a nonlinear interface and the simple integration technique may warrant increased interest in this approach to optical computing.