Entwicklung einer Glucosedehydrogenase-basierten Anode und deren Anwendung in einer Glucose/O2-Biobrennstoffzelle

Unter Verwendung von mehrwandigen Kohlenstoffnanoröhren wurde in dieser Studie eine neuartige Anode zum Einsatz in Biobrennstoffzellen entwickelt. Dazu wurde das rekombinante Enzym Pyrrolochinolinchinon(PQQ)- abhängige Glucosedehydrogenase kovalent an eine aus PQQ bestehenden Zwischenschicht gekoppelt, welche zuvor an die Kohlenstoffnanoröhren adsorbiert war. Die Nanoröhren wurden aufgrund ihrer Thiolmodifikation chemisorptiv auf einer Goldelektrode gebunden. In glucosehaltiger Lösung konnte der Start eines katalytischen Stroms bei einem Potential von -80 mV vs. Ag/AgCl (1 MKCl) beobachtet werden. Unter Substratsättigung wurden Stromdichten im Bereich von 170 bis 200 μA/cm2 gemessen. Dieses System basiert auf einem mediatorvermittelten Elektronentransfer. Die entwickelte (PQQ)-GDH-MWCNT-Elektrode wurde mit einer MWCNT-modifizierten Elektrode kombiniert, bei der Bilirubinoxidase (BOD) als Biokatalysator fungiert. Daraus resultierte eine membranfreie Biobrennstoffzelle mit einem leichgewichtspotential von 600 mV und Leistungsdichten im Bereich von 20-25 μW/cm2.In this study a biofuel cell anode is developed on the basis of multi-walled carbon nanotubes (MWCNTs). Recombinant pyrroloquinoline quinone (PQQ) dependent glucose dehydrogenase is covalently coupled to a PQQ-layer which is adsorbed onto thiolmodified MWCNTs. The MWCNTs are chemisorbed to a gold electrode. In the presence of glucose a catalytic current starts at a potential of -80 mV vs. Ag/AgCl, 1 M KCl. Under substrate saturation current densities of 170 to 200 μA/cm2 can be achieved. The operation is based on mediated electron transfer of the enzyme. This (PQQ)-GDH-MWCNT-electrode is combined with a MWCNT-modifi ed electrode to which bilirubin oxidase (BOD) is covalently coupled. The resulting membrane-free biofuel cell has an open cell potential of 600 mV and can achieve power densities in the range of 20-25 μW/cm2

Biomechanical and clinical assessment for jaw movement and the related TMJ loading in patients with temporomandibular joint disorders

Temporomandibular joint disorders (TMD) have been demonstrated to be a multifactorial in nature. Possible explanations for the causes have been documented in the literature indicating excessive loading during jaw movement and the subsequent biomechanical imbalance in the TMJ may be assumed as an initial factor for a series of degenerative changes, resulting in condylar resorption and deformity. Therefore, an evaluation of the biomechanical environment in the TMJ would lead to a better understanding of the inducing mechanism of TMJ pain and disability, which result in proper diagnosis and available treatment planning for TMD. Recently, we developed an individual three-dimensional modeling system for the TMJ components based on the magnetic resonance (MR) image and the subsequent analysis of the TMJ loading during jaw movement. The present study was thus designed to introduce biomechanical and clinical assessment of jaw movement and the subsequent joint loading in patients with TMD. Furthermore, we would like to show a case of TMD patient treated with orthodontic approach to introduce an example of the assessment with this system

Activation of caspase-1 by the NLRP3 inflammasome regulates the NADPH oxidase NOX2 to control phagosome function

Phagocytosis is a fundamental cellular process that is pivotal for immunity as it coordinates microbial killing, innate immune activation and antigen presentation. An essential step in this process is phagosome acidification, which regulates a number of functions of these organelles that allow them to participate in processes essential to both innate and adaptive immunity. Here we report that acidification of phagosomes containing Gram-positive bacteria is regulated by the NLRP3-inflammasome and caspase-1. Active caspase-1 accumulates on phagosomes and acts locally to control the pH by modulating buffering by the NADPH oxidase NOX2. These data provide insight into a mechanism by which innate immune signals can modify cellular defenses and establish a new function for the NLRP3-inflammasome and caspase-1 in host defense

Daily jaw muscle activity in freely moving rats measured with radio-telemetry.

The jaw muscle activity of rats has been investigated for specific tasks. However, the daily jaw muscle use remains unclear. The purpose of the present study was to examine daily jaw muscle activity, and its variability over time, in the rat (n = 12) by the use of radio-telemetry. A telemetric device was implanted for the continuous recording of masseter muscle and digastric muscle activity. Daily muscle use was characterized by calculating the total time that each muscle was active (duty time), the number of bursts, and the average length of bursts. All parameters were estimated for activities exceeding various levels (5-90%) of the day's peak activity. Daily muscle use remained constant for 4 wk. At the low-activity level, the duty time and burst number of the digastric muscle were significantly (P < 0.01) higher than those of the masseter muscle, whereas the opposite was true at the high-activity level (P < 0.05). No significant intermuscular correlation was observed between the number of bursts of the masseter and digastric muscles, but the interindividual variation of both muscles changed, depending on the level of activation. These findings suggest that the masseter muscle and the digastric muscle show a differential active pattern, depending on the activity level. © 2007 The Authors. Journal compilation 2007 Eur J Oral Sci

Education of dentists in China

China is geographically located in the east of Asia and its population exceeds 1.3 billion. An understanding of dental education in China is thus of interest. However, as there is little published information on this topic, this paper provides information about China regarding its dental history, dental school system including curriculum and dental licensure. High school graduates take a nationwide entrance examination to apply for dental school, of which there are more than 50 in China. A five year dental education leads to the BDS degree. Dental school graduates must then pass the nationwide licensure examination to practise dentistry. Currently, there are not adequate numbers of dentists to provide the necessary oral health care for people living outside metropolitan areas

A randomised controlled trial of antiplatelet therapy in combination with Rt-PA thrombolysis in ischemic stroke: rationale and design of the ARTIS-Trial

<p>Abstract</p> <p>Background</p> <p>Thrombolysis with intravenous rt-PA is currently the only approved acute therapy for ischemic stroke. Re-occlusion after initial recanalization occurs in up to 34% in patients treated with rt-PA, probably caused by platelet activation. In acute myocardial infarction, the combination of thrombolysis and antiplatelet therapy leads to a greater reduction of mortality compared to thrombolysis alone. In patients with acute ischemic stroke, several studies showed that patients already on antiplatelet treatment prior to thrombolysis had an equal or even better outcome compared to patients without prior antiplatelet treatment, despite an increased risk of intracerebral bleeding. Based on the fear of intracerebral haemorrhage, current international guidelines recommend postponing antiplatelet therapy until 24 hours after thrombolysis. Remarkably, prior use of antiplatelet therapy is not a contra-indication for thrombolysis. We hypothesize that antiplatelet therapy in combination with rt-PA thrombolysis will improve outcome by enhancing fibrinolysis and preventing re-occlusion.</p> <p>Methods/Design</p> <p>ARTIS is a randomised multi-center controlled trial with blind endpoint assessment. Our objective is to investigate whether immediate addition of aspirin to rt-PA thrombolysis improves functional outcome in ischemic stroke. Patients with acute ischemic stroke eligible for rt-PA thrombolysis are randomised to receive 300 mg aspirin within 1.5 hours after start of thrombolysis or standard care, consisting of antiplatelet therapy after 24 hours. Primary outcome is poor functional health at 3 months follow-up (modified Rankin Scale 3 - 6).</p> <p>Discussion</p> <p>This is the first clinical trial investigating the combination of rt-PA and acute aspirin by means of a simple and cheap adjustment of current antiplatelet regimen. We expect the net benefit of improved functional outcome will overcome the possible slightly increased risk of intracerebral haemorrhage.</p> <p>Trial registration</p> <p>The Netherlands National Trial Register NTR822. The condensed rationale of the ARTIS-Trial has already been published in Cerebrovascular Diseases.</p

Prevalence of nonmedical methamphetamine use in the United States

<p>Abstract</p> <p>Background</p> <p>Illicit methamphetamine use continues to be a public health concern in the United States. The goal of the current study was to use a relatively inexpensive methodology to examine the prevalence and demographic correlates of nonmedical methamphetamine use in the United States.</p> <p>Methods</p> <p>The sample was obtained through an internet survey of noninstitutionalized adults (n = 4,297) aged 18 to 49 in the United States in 2005. Propensity weighting methods using information from the U.S. Census and the 2003 National Survey on Drug Use and Health (NSDUH) were used to estimate national-level prevalence rates.</p> <p>Results</p> <p>The overall prevalence of current nonmedical methamphetamine use was estimated to be 0.27%. Lifetime use was estimated to be 8.6%. Current use rates for men (0.32%) and women (0.23%) did not differ, although men had a higher 3-year prevalence rate (3.1%) than women (1.1%). Within the age subgroup with the highest overall methamphetamine use (18 to 25 year olds), non-students had substantially higher methamphetamine use (0.85% current; 2.4% past year) than students (0.23% current; 0.79% past year). Methamphetamine use was not constrained to those with publicly funded health care insurance.</p> <p>Conclusion</p> <p>Through the use of an internet panel weighted to reflect U.S. population norms, the estimated lifetime prevalence of methamphetamine use among 18 to 49 year olds was 8.6%. These findings give rates of use comparable to those reported in the 2005 NSDUH. Internet surveys are a relatively inexpensive way to provide complimentary data to telephone or in-person interviews.</p