Embolic materials for cerebral endovascular theraphy

Cerebral embolization is one of the most important procedures in neuroendovasculare intervention. Fast developments of new microcatheters that can be maneuvered endovascularly into the brain have permitted the treatment of lesions without conventional neurosurgery. Also, the progress in biomaterial science has contributed significantly to the development of this new therapeutic modality. Various embolic materials in clinical use are reviewed, such as cyanoacrylates, ethylene-vinyl alcohol copolymer mixtures, Ethibloc, ethanol, estrogen, poly(vinyl acetate), cellulose acetate polymer, poly(vinyl alcohol), gelatin sponges, microfibrillar collagen, surgical silk sutures, detachable balloons, and coils. These materials are reviewed in the context of treatment application for various brain lesions, such as arteriovenous malformations, cerebral aneurysms, and head and neck tumors. Further developments in biomaterial polymer science can bring about progress against brain diseases

Adaptation and acclimatization to ocean acidification in marine ectotherms: an in situ transplant experiment with polychaetes at a shallow CO₂ vent system

Metabolic rate determines the physiological and life-history performances of ectotherms. Thus, the extent to which such rates are sensitive and plastic to environmental perturbation is central to an organism's ability to function in a changing environment. Little is known of long-term metabolic plasticity and potential for metabolic adaptation in marine ectotherms exposed to elevated pCO₂. Consequently, we carried out a series of in situ transplant experiments using a number of tolerant and sensitive polychaete species living around a natural CO₂ vent system. Here, we show that a marine metazoan (i.e. Platynereis dumerilii) was able to adapt to chronic and elevated levels of pCO₂. The vent population of P. dumerilii was physiologically and genetically different from nearby populations that experience low pCO₂, as well as smaller in body size. By contrast, different populations of Amphiglena mediterranea showed marked physiological plasticity indicating that adaptation or acclimatization are both viable strategies for the successful colonization of elevated pCO₂ environments. In addition, sensitive species showed either a reduced or increased metabolism when exposed acutely to elevated pCO₂. Our findings may help explain, from a metabolic perspective, the occurrence of past mass extinction, as well as shed light on alternative pathways of resilience in species facing ongoing ocean acidification

Critical magnetic fluctuations induced superconductivity and residual density of states in CeRhIn5CeRhIn_5 superconductor

We propose the multiband extension of the spin-fermion model to address the superconducting d-wave pairing due to magnetic interaction near critical point. We solve the unrestricted gap equation with a general d-wave symmetry gap and find that divergent magnetic correlation length $\xi$ leads to the very unharmonic shape of the gap function with shallow gap regions near nodes. These regions are extremely sensitive to disorder. Small impurity concentration induces substantial residual density of states. We argue that we can understand the large $N_{res}(0) = \lim_{T\to 0} C_p(T)/T$ value and its pressure dependence of the recently discovered $CeRhIn_5$ superconductor under pressure within this approach.Comment: 5 figure

Delivery of liposome membrane-associated sterols through silastic membranes

The transport of sterols incorporated into the lecithin bilayer of small unilamellar liposomes through a model membrane was studied. A two-chamber diffusion cell containing liposomes with incorporated [4-14C]cholesterol or [beta]-[4-14C]sitosterol in the donor chamber and liposomes with unlabeled cholesterol in the receiver chamber was used. The permeability coefficients of the sterols through silastic rubber membranes which served as a model membrane were measured. The permeability for cholesterol incorporated into liposomes in a phosphatidyl choline/cholesterol molar ratio of 1 : 1, produced by sonication for 1 h, and subsequent centrifugation at 100000 x g for 1 h, was 1.6 [middle dot] 10-8 cm sec-1. Dilution of the liposome suspension did not change the permeability coefficient significantly. The permeability coefficient of sitosterol incorporated into liposomes was about 4-times smaller than that of cholesterol. These results suggest that the sterols were delivered to the silastic membrane by the intact liposomes and that free solute was not involved in the transport to the membrane to a significant degree. The large differences in the permeability coefficients between cholesterol and sitosterol indicate that an aqueous interfacial barrier was crossed by the sterol during the delivery to the membrane.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/24282/1/0000548.pd

Spin glasses and algorithm benchmarks: A one-dimensional view

Spin glasses are paradigmatic models that deliver concepts relevant for a variety of systems. However, rigorous analytical results are difficult to obtain for spin-glass models, in particular for realistic short-range models. Therefore large-scale numerical simulations are the tool of choice. Concepts and algorithms derived from the study of spin glasses have been applied to diverse fields in computer science and physics. In this work a one-dimensional long-range spin-glass model with power-law interactions is discussed. The model has the advantage over conventional systems in that by tuning the power-law exponent of the interactions the effective space dimension can be changed thus effectively allowing the study of large high-dimensional spin-glass systems to address questions as diverse as the existence of an Almeida-Thouless line, ultrametricity and chaos in short range spin glasses. Furthermore, because the range of interactions can be changed, the model is a formidable test-bed for optimization algorithms.Comment: 10 pages, 8 figures (two in crappy quality due to archive restrictions). Proceedings of the International Workshop on Statistical-Mechanical Informatics 2007, Kyoto (Japan) September 16-19, 200

Chirality scenario of the spin-glass ordering

Detailed account is given of the chirality scenario of experimental spin-glass transitions. In this scenario, the spin glass order of weakly anisotropic Heisenberg-like spin-glass magnets including canonical spin glasses are essentially chirality driven. Recent numerical and experimental results are discussed in conjunction with this scenario.Comment: Submitted to J. Phys. Soc. Japan "Special Issue on Frustration

Hysteresis loop signatures of phase transitions in a mean-field model of disordered Ising magnet

In accordance with recent experiments the mean-field type theories predict the presence of numerous metastable minima (states) in the rugged free-energy landscape of frustrated disordered magnets. This multiplicity of long-lived states with lifetimes greater than $10^5 s$ makes the task to experimentally determine which of them has the lowest free energy (and thus what thermodynamic phase the sample is in) seem rather hopeless the more so as we do not know a protocol (such as field-cooling or zero-field-cooling) leading to the equilibrium state(s). Nevertheless here we show in the framework of Landau-type phenomenological model that signatures of the mean-field equilibrium phase transitions in such highly nonequilibrium systems may be found in the evolution of the hysteresis loop form. Thus the sequence of transitions from spin-glass to mixed phase and to ferromagnetic one results in the changes from inclined hysteresis loop to that with the developing vertical sides and to one with the perfectly vertical sides. Such relation between loop form and the location of global minimum may hold beyond the mean-field approximation and can be useful in the real experiments and Monte-Carlo simulations of the problems involving rugged potential landscape. Also the very existence of the quasi-static loops in spin glass and mixed phases implies that the known disorder-smoothing of the first-order transition can be always accompanied by the emergence of multiple metastable states.Comment: 5 pages, 4 figures; misprints corrected, slight deviations from published version (abstract and references

OBEDIS Core Variables Project : European Expert Guidelines on a Minimal Core Set of Variables to Include in Randomized, Controlled Clinical Trials of Obesity Interventions

Heterogeneity of interindividual and intraindividual responses to interventions is often observed in randomized, controlled trials for obesity. To address the global epidemic of obesity and move toward more personalized treatment regimens, the global research community must come together to identify factors that may drive these heterogeneous responses to interventions. This project, called OBEDIS (OBEsity Diverse Interventions Sharing - focusing on dietary and other interventions), provides a set of European guidelines for a minimal set of variables to include in future clinical trials on obesity, regardless of the specific endpoints. Broad adoption of these guidelines will enable researchers to harmonize and merge data from multiple intervention studies, allowing stratification of patients according to precise phenotyping criteria which are measured using standardized methods. In this way, studies across Europe may be pooled for better prediction of individuals' responses to an intervention for obesity - ultimately leading to better patient care and improved obesity outcomes.Peer reviewe

The health care setting rather than medical speciality impacts on physicians adherence to guideline-conform anticoagulation in outpatients with non-valvular atrial fibrillation: a cross sectional survey

BACKGROUND: In patients with non-valvular atrial fibrillation (NVAF) at high risk for stroke guidelines consistently recommend long-term oral anticoagulation (OAC) with a vitamin K antagonist. However recommendations remain ambiguous in respect to the precise OAC initiation regimens. Based on the clinical observation, that the initiation of OAC for NVAF varies considerably in daily practice, we aimed to assess the current practice in Switzerland. METHODS: Cross-sectional survey of randomly selected general practitioners, internists and cardiologists from different health care settings in an urban Swiss region that covers 1.4 million inhabitants. The main outcome measures were the preferred antithrombotic initiation regimen and long-term treatment in patients with newly diagnosed NVAF at high risk for stroke. RESULTS: We received 226 out of 388 (58.2%) surveys. Compared to physicians working in a hospital setting (33.6% of respondents) physicians in ambulatory care reported more years of experience and claimed lower-use (never or seldom) of guidelines in general (47.6 vs. 12.2%). Regarding long-term thromboembolic prophylaxis 93.7% of all responders followed current recommendation by choosing an OAC. When focussing on guideline-consistent correct OAC initiation (either low-dose initial OAC or a combination of LMWH and OAC) adherence dropped to 60.6% with hospital physicians demonstrating a significantly higher use of guideline-conform OAC regimens (79.7 vs. 51.0%). Medical speciality in non-hospital physicians was not related to correct guideline-use. Hospital setting remained independently associated with a guideline-conform OAC initiation regimen (OR 2.8, p = 0.023) when controlled for medical speciality, physicians' characteristics and clinical experience. Problems when starting an anticoagulation treatment were seldom reported (never or seldom accounting for 94.1% of all responses). CONCLUSIONS: The guideline adherence with respect to OAC initiation regimens in NVAF was significantly lower when compared to long-term treatment and health care setting rather than medical speciality explained guideline-conform OAC initiation. The majority of the physicians did not consider the initiation of anticoagulation to be a major obstacle in outpatient care

A highly efficacious pediculicide based on dimeticone: Randomized observer blinded comparative trial

BACKGROUND: Infestation with the human head louse (Pediculus humanus capitis) occurs worldwide. Existing treatment options are limited, and reports of resistance to commonly used pediculicides have been increasing. In this trial we assessed the efficacy of a product containing a high (92%) concentration of the silicone oil dimeticone (identical in composition to NYDA(R)), as compared to a 1% permethrin lotion. METHODS: Randomized, controlled, observer blinded clinical trial. Participants were recruited from a poor urban neighbourhood in Brazil where pediculosis capitis was highly prevalent. To minimize reinfestation during the trial, participants (145 children aged 5-15 years with head lice infestations) were transferred to a holiday resort outside the endemic area for a period of 9 days. Two applications of dimeticone or 1% permethrin were done, seven days apart. Outcome measures were defined as cure (absence of vital head lice) after first application and before and after second applications, degree of itching, cosmetic acceptability, and clinical pathology. RESULTS: Overall cure rates were: day 2 - dimeticone 94.5% (95% CI: 86.6% - 98.5%) and permethrin 66.7% (95% CI: 54.6% - 77.3%; p < 0.0001); day 7 - dimeticone 64.4% (95% CI: 53.3% - 75.3%) and permethrin 59.7% (95% CI: 47.5% - 71.1%; p = 0.5); day 9 - dimeticone 97.2% (95% CI: 90.3% - 99.7%) and permethrin 67.6% (95% CI: 55.4%-78.2%); p < 0.0001). Itching was reduced similarly in both groups. Cosmetic acceptability was significantly better in the dimeticone group as compared to the permethrin group (p = 0.01). Two mild product-related incidents occurred in the dimeticone group. CONCLUSION: The dimeticone product is a safe and highly efficacious pediculicide. Due to its physical mode of action (interruption of the lice's oxygen supply of the central nervous system), development of resistance is unlikely. TRIAL REGISTRATION: Current Controlled Trials ISRCTN15117709