Biotreibstoffe aus Entwicklungsländern: Eine Lebenszyklusbetrachtung

Das Kyoto-Protokoll zur Treibhausgasreduktion und steigende Ölpreise, aber auch Lobbyarbeit vom Landwirtschaftssektor und von der Automobilindustrie haben global zu einem Boom der Biotreibstoffe geführt. Aufgrund des durch die Agrarflächen beschränkten Mengen-Potenzials, der absehbaren Konkurrenz zur Nahrungsmittelproduktion und den oftmals hohen Umweltauswirkungen liegt das nachhaltige Marktpotenzial von Biotreibstoffen deutlich unter 10% des gesamten weltweiten Treibstoffkonsums. Trotz dieser Nachteile existieren gerade in Entwicklungsländern auch Nischen für die nachhaltige Produktion von Bioenergie. Oftmals ist es dabei sinnvoller, Biomasse für lokale Strom- und Wärmeproduktion zu nutzen, statt Biotreibstoffe für den Export zu produzieren.

Glycan-binding specificities of Streptococcus mutans and Streptococcus sobrinus lectin-like adhesins

Since the adhesion of bacteria to the tooth surface is a prerequisite for dental plaque and subsequent caries development, a promising caries preventive strategy could be to block the lectin-glycan-mediated adherence of cariogenic bacteria. The aim of the study was to evaluate potential differences in glycan-binding specificities of two Streptococcus mutans strains (DSM 20523 and DSM 6178) and Streptococcus sobrinus (DSM 20381). A competitive enzyme-linked lectin-binding assay was used to identify the binding specificities of isolated bacterial surface lectins. Blotting of the microbial proteins on neoglycoprotein-coated PVP membranes enabled a qualitative protein analysis of all specific bacterial lectins. Different glycan-binding sites could be identified for the S. mutans strains in comparison to S. sobrinus. An earlier reported glycan-binding specificity for terminal galactose residues could be confirmed for the S. mutans strains. For the S. sobrinus strain, more than one glycan-binding specificity could be found (oligomannose and terminal sialyl residues). Each of the tested strains showed more than one surface lectin responsible for the specific lectin-binding with varying molecular weight (S. mutans, 90/155 kDa and S. sobrinus, 35/45 kDa). The established experimental setup could be used as future standard procedure for the identification of bacterial lectin-derived binding specificities. The findings from this study might serve as basis for the design of an individual 'glycan cocktail' for the competitive inhibition of lectin-mediated adhesion of mutans streptococci to oral surfaces.

Are endodontically treated incisors reliable abutments for zirconia-based fixed partial dentures in the esthetic zone?

This ex vivo pilot study tested the influence of defect extension and quartz-fiber post placement (QFP) on the ex vivo survival rate and fracture resistance of root-treated upper central incisors served as abutments for zirconia 2-unit cantilever fixed partial dentures (2U-FPDs) exposed to 10 years of simulated clinical function.

Hematometra presenting as an acute abdomen in a 13-year-old postmenarchal girl: a case report

Introduction Most underlying diseases for abdominal pain in children are not dangerous. However some require rapid diagnosis and treatment, such as acute ovarian torsion or appendicitis. Since reaching a diagnosis can be difficult, and delayed treatment of potentially dangerous diseases might have significant consequences, exploratory laparoscopy is a diagnostic and therapeutic option for patients who have unclear and potentially hazardous abdominal diseases. Here we describe a case where the anomaly could not be identified using a laparoscopy in an adolescent girl with acute abdomen. Case presentation A 13-year old postmenarchal caucasian female presented with an acute abdomen. Emergency sonography could not exclude ovarian torsion. Accurate diagnosis and treatment were achieved only after an initial laparoscopy followed by a laparotomy and after a magnetic resonance imaging scan a further laparotomy. The underlying disease was hematometra of the right uterine horn in a uterus didelphys in conjunction with an imperforate right cervix. Conclusion This report demonstrates that the usual approach for patients with acute abdominal pain may not be sufficient in emergency situations.

Myocardial blood volume and coronary resistance during and after coronary angioplasty

Animal experiments have shown that the coronary circulation is pressure distensible, i.e., myocardial blood volume (MBV) increases with perfusion pressure. In humans, however, corresponding measurements are lacking so far. We sought to quantify parameters reflecting coronary distensibility such as MBV and coronary resistance (CR) during and after coronary angioplasty. Thirty patients with stable coronary artery disease underwent simultaneous coronary perfusion pressure assessment and myocardial contrast echocardiography (MCE) of 37 coronary arteries and their territories during and after angioplasty. MCE yielded MBV and myocardial blood flow (MBF; in ml · min(-1) · g(-1)). Complete data sets were obtained in 32 coronary arteries and their territories from 26 patients. During angioplasty, perfusion pressure, i.e., coronary occlusive pressure, and MBV varied between 9 and 57 mmHg (26.9 ± 11.9 mmHg) and between 1.2 and 14.5 ml/100 g (6.7 ± 3.7 ml/100 g), respectively. After successful angioplasty, perfusion pressure and MBV increased significantly (P < 0.001 for both) and varied between 64 and 118 mmHg (93.5 ± 12.8 mmHg) and between 3.7 and 17.3 ml/100 g (9.8 ± 3.4 ml/100 g), respectively. Mean MBF increased from 31 ± 20 ml · min(-1) · g(-1) during coronary occlusion, reflecting collateral flow, to 121 ± 33 ml · min(-1) · g(-1) (P < 0.01), whereas mean CR, i.e., the ratio of perfusion pressure and MBF, decreased by 20% (P < 0.001). In conclusion, the human coronary circulation is pressure distensible. MCE allows for the quantification of CR and MBV in humans.