Molecular identification tools for sibling species of Scedosporium and Pseudallescheria

The aim of this study was to develop molecular identification tools for currently recognized species of Pseudallescheria and Scedosporium through the use of species-specific primers and RFLP, so as to enhance rapid differentiation of clinically relevant species. The variability of species was established in a set of 681 Internal Transcribed Spacer (ITS) and 349 ß-tubulin (BT2) sequences. Amplified Fragment Length Polymorphism profile clustering matched with BT2 results, whereas ITS grouping was less detailed. ITS was sufficient for the differentiation of most haplotypes of clinically relevant species (P. apiosperma, P. boydii, S. aurantiacum, S. dehoogii, and S. prolificans) and of environmental species (P. minutispora and Lophotrichus fimeti) when Restriction Fragment Length Polymorphism (RFLP) were applied. For the identification of P. apiosperma and P. boydii species-specific BT2 primers were needed. Pseudallescheria fusoidea, P. ellipsoidea and P. angusta remained difficult to distinguish from P. boydii.

Identification of Pseudallescheria and Scedosporium species by three molecular methods

The major clinically relevant species in Scedosporium (teleomorph Pseudallescheria) are Pseudallescheria boydii, Scedosporium aurantiacum, Scedosporium apiospermum, and Scedosporium prolificans, while Pseudallescheria minutispora, Petriellopsis desertorum, and Scedosporium dehoogii are exceptional agents of disease. Three molecular methods targeting the partial β-tubulin gene were developed and evaluated to identify six closely related species of the S. apiospermum complex using quantitative real-time PCR (qPCR), PCR-based reverse line blot (PCR-RLB), and loop-mediated isothermal amplification (LAMP). qPCR was not specific enough for the identification of all species but had the highest sensitivity. The PCR-RLB assay was efficient for the identification of five species. LAMP distinguished all six species unambiguously. The analytical sensitivities of qPCR, PCR-RLB, and LAMP combined with MagNAPure, CTAB (cetyltrimethylammonium bromide), and FTA filter (Whatman) extraction were 50, 5 × 10(3), and 5 × 10(2) cells/μl, respectively. When LAMP was combined with a simplified DNA extraction method using an FTA filter, identification to the species level was achieved within 2 h, including DNA extraction. The FTA-LAMP assay is therefore recommended as a cost-effective, simple, and rapid method for the identification of Scedosporium species.

Spektroskopischer Einsatz neuer langwelliger (bis 2 μm) Diodenlaser (VCSEL) für schwierige Bedingungen (Spectroscopic Application of Long-Wavelength (< 2 μm) VCSEL Diode Lasers)

Oberflächenemittierende Diodenlaser (engl. VCSEL, Vertical-cavity surface-emitting laser) werden zur raschen direkten In-situ-Molekülspektroskopie eingesetzt. Nach dem Verfahren der Absorptionsspektroskopie mittels durchstimmbarer Diodenlaser wird Sauerstoff bei 760 nm, Ammoniak bei 1540 nm, Methan bei 1680 nm sowie Chlorwasserstoff und Wasser bei 1810 nm detektiert. Druckverbreiterte und hochaufgelöste Spektren werden gezeigt und das Prinzip eines langzeitstabilen Spektrometers vorgestellt. Die Wellenlängenmodulation der VCSEL mit der Temperatur und dem Strom wird untersucht. Während der Temperaturkoeffizient in etwa derselbe ist wie für herkömmliche Diodenlaser im nahen Infrarot (DFB-Laser), lassen sich VCSEL deutlich weiter mit dem Strom durchstimmen. Darüber hinaus können VCSEL thermisch wesentlich schneller moduliert werden als konventionelle Kantenemitter. Repetitionsraten bis 5 MHz werden demonstriert. Die neu eröffneten Anwendungsfelder im Hinblick auf den weiten, modensprungfreien Durchstimmbereich (Messung bei hohem Druck, mehrere Spezies, Temperaturverteilungen) und die rasche Modulierbarkeit (Messung extrem transienter Prozesse) werden diskutiert. Weiter werden spektroskopisch interessante Eigentümlichkeiten der VCSEL (geringer Schwellstrom und Strombedarf als Vorteil für batteriebetriebene mobile Geräte, Austestmöglichkeit auf der Waferebene) beleuchtet. Die langwelligen VCSEL mit λ > 1 μm auf InP-Basis existieren noch nicht lange. Es wird angenommen, dass diese demnächst verstärkten Einzug in die Molekülspektroskopie halten werden und das Einsatzgebiet von auf Diodenlasern basierenden Geräten beträchtlich nach höheren Drücken und schwierigen Bedingungen hin erweitern werden.

CO and CO2 spectroscopy using a 60 nm broadband tunable MEMS-VCSEL at approximately 1.55 microm

The spectroscopic application of a new broadband microelectromechanical-system-tunable vertical cavity surface-emitting laser with single-mode coverage of 60 nm (245 cm(-1)) in a single, continuous sweep is described. The operation of the device is illustrated with high-resolution spectra of CO and CO2 over 110 cm(-1) (27 nm) and 67 cm(-1) (17 nm), respectively, with the CO band shown for high-pressure scans between 1 and 3 bars (0.1-0.3 MPa). The achieved tuning range opens up new opportunities for tunable diode laser absorption spectroscopy. The spectra were compared with HITRAN-derived model calculations. The benefits of a sensor based on this laser are greater speed, laser power, and tuning range.

Investigation of the early stages in laser-induced ignition by Schlieren photography and laser-induced fluorescence spectroscopy

Laser ignition has been discussed widely as a potentially superior ignition source for technical appliances such as internal combustion engines. Ignition strongly affects overall combustion, and its early stages in particular have strong implications on subsequent pollutant formation, flame quenching, and extinction. Our research here is devoted to the experimental investigation of the early stages of laser-induced ignition of CH4/air mixtures up to high pressures. Tests were performed in a 0.9-l combustion cell with initial pressures of up to 25 bar with stoichiometric to fuel-lean mixtures using a 5-ns 50-mJ 1064-nm Nd:YAG laser. Laserinduced fluorescence (LIF) was used to obtain two dimensionally resolved images of the OH radical distribution after the ignition event. These images were used to produce an animation of laser ignition and early flame kernel development. Schlieren photography was used to investigate the laserinduced shock wave, hot core gas, and developing flame ball. We extend existing knowledge to high-pressure regimes relevant for internal combustion engines.

In situ investigation of laser-induced ignition and the early stages of methane-air combustion at high pressures using a rapidly tuned diode laser at 2.55 microm

The laser-induced ignition of methane/air-mixtures at elevated pressures was investigated by an absorption spectroscopic technique. A room temperature continuous wave InGaAsSb/AlGaAsSb quantum well ridge diode laser was wavelength tuned around 2.55 mum by periodically modulating the injection current from 0 to 174 mA at a 5 kHz repetition rate. The laser heat sink temperature was fixed at 291 K. The infrared laser beam was sent through the pressurized combustion vessel perpendicularly to the igniting laser beam (Nd:YAG laser, 10 ns pulse duration, 20 mJ) at the position of the ignition spark. Fuel-rich to fuel-lean mixtures of methane/air (air equivalence ratio 0.89, 1.06, 1.42, 2.50) were investigated at initial pressures of up to 3 MPa. The initial temperature was 473 K, the volume of the combustion vessel 0.9x10(-3) m(3). The formation of water vapor in the vicinity of the laser spark was tracked by the diode laser. The time resolution of the measurements was 0.2 ms for a total continuous measurement time of up to 1 s. In this way, the laser-induced ignition and its accompanying effects could be investigated on a time scale spanning four orders of magnitude. Apart from the absorbance of water vapor which could be determined semi-quantitatively (due to the effects of severe pressure broadening at high pressures and the ignorance of the exact temperature distribution after ignition), the emissions from the flame (broadband, 1-10 mum) and a gas inhomogeneity index were recorded. The gas inhomogeneity index was obtained by extracting a frequency variable from the time-dependent fluctuations of the transmitted laser intensities and calculating its derivation. The absorbance of water vapor, the emissions from the flame and the gas inhomogeneity index were found to be a powerful tool to characterize laser-induced ignition. Major implications of in situ species concentration measurements at high pressures for the design and development of high-load combustors are presented.

Erythema multiforme associated human autoantibodies against desmoplakin I and II: biochemical characterization and passive transfer studies into newborn mice

The demonstration of circulating autoantibodies directed against the constitutive desmosomal plaque proteins desmoplakin (dp) I and II in mucocutaneous lesions in a subset of patients with erythema multiforme major, suggests that humoral immune mechanisms may play a role in the pathogenesis of this severe skin disease. In this study we identified a specific peptide sequence--YSYSYS--representing an antigenic binding site for the human autoantibodies. This epitope is localized at the extreme carboxy terminal domain of dp thought to be responsible for the assembly of keratin filaments with desmosomes. To test the possibility whether these antibodies may exert any pathologic effects in vivo, human autoantibodies were affinity purified on a corresponding synthetic peptide matrix and peptide-specific antibodies were raised in rabbits. After repeated subcutaneous injections into newborn mice, affinity-purified human autoantibodies and anti-peptide rabbit IgG were detected on desmosomal plaques of keratinocytes overlying the injection site. Histologic and electron microscopic examinations showed hydropic degeneration of basal and suprabasal keratinocytes, dyskeratosis, signs of suprabasal acantholysis, and keratin filaments detached from the desmosomal plaques clumping around the nucleus. We demonstrate that autoantibodies are directed to an epitope within a dp domain crucial for the interaction of keratin filaments with desmosomes, and, when injected subcutaneously into newborn mice, produce pathologic changes. These findings imply that autoantibodies to dp could impair the function of desmosome-keratin filament complexes suggesting a pathogenic role in vivo.

[Patient-medical staff-consultant triad: conditions for satisfaction in psychosomatic consultation service]

In a large 1000 bed University Medical Center the psychosomatic consultation service (PCS) was evaluated by a two step investigation. 1. Housemen (interns) and senior staff members were asked by questionnaires about their previous experiences with psychological medicine and particularly about their satisfaction with the PCS and how they would estimate the need for additional psychosomatic treatment for the patients on their ward. A striking disproportion was found between actual requests (1.8%) for PCS and the estimated need (18%) for additional psychosomatic advice or treatment. 2. Questionnaires dealing with satisfaction were given to the consultant, the patient and the consultee. The satisfaction of the consulte was mainly determined by the promptness in answering his request and formal aspects of the exchange, the patient satisfaction was mainly determined by the way they viewed the help, the sense of importance of the consultation and by the feeling of being understood by the consultant. This seems to influence the future compliance. Surprisingly, a correlation between the patient satisfaction with the consultation and the quantitative and qualitative aspects of exchange between consultant and consultee was less clearly demonstrated. This could be seen as a hint of communication problems between the consultee and his patient, the improvement of which is one of the main concerns of psychosomatic consultation.

[Comparison of the antibacterial efficacy of doxycycline and tetracycline (author's transl)]

In order to explain the mechanism of resistance within the tetracycline group, the minimal inhibitory concentration of tetracycline HCl was compared with that of doxycycline in the micro dilution test for bacterial collectives of 48 strains each from the groups of gram-negative and gram-positive cocci, resp. There was no significant difference between the inhibitory effect of doxycycline and tetracycline HCl for the bacterial collectives of E. coli, Klebsiella, Proteus and Staphylococcus aureus heamolyticus strains which were inhibited by a relatively low concentration of tetracycline HCl and doxycycline, respectively. On the other hand a significant difference in inhibitory effect was observed the calculation was made according to the Kolmogoroff-Smirnov test for the bacterial collectives of Enterococci and Staphylococcus aureus haemolyticus strains which were tetracycline resistant or only inhibited by higher concentrations. These results also have a practical importance, because a further testing against doxycycline can bring about a sensitivity to this substance in case of tetracycline resistant grampositive cocci. Possible explanations for the higher efficacy of doxycycline on these bacterial collectives will be discussed.