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Biomedical subjects

M Gebhard

Publications and source records attributed to M Gebhard.

7 recordsLinked to original sources
PubMed2006

Observation of muon neutrino disappearance with the MINOS detectors in the NuMI neutrino beam.

This Letter reports results from the MINOS experiment based on its initial exposure to neutrinos from the Fermilab NuMI beam. The rates and energy spectra of charged current nu(mu) interactions are compared in two detectors located along the beam axis at distances of 1 and 735 km. With 1.27 x 10(20) 120 GeV protons incident on the NuMI target, 215 events with energies below 30 GeV are observed at the Far Detector, compared to an expectation of 336+/-14 events. The data are consistent with nu(mu) disappearance via oscillations with |Delta(m)2/32|=2.74 +0.44/-0.26 x10(-3)eV(2) and sin(2)(2theta(23))>0.87 (68% C.L.).

Journal Article↗
PubMed2002

MR arthrography: pharmacology, efficacy and safety in clinical trials.

OBJECTIVE: A meta-analysis was carried out of clinical trials published between 1987 and 2001 in respect of the clinical pharmacology and safety as well as the diagnostic efficacy of gadolinium-DTPA (Gd-DTPA) for direct intra-articular injection before MRI examination. DESIGN: Scientific papers (clinical, postmortem and experimental studies) and information from the manufacturer regarding intra-articular injection of Gd-DTPA that addressed questions of mode of action, optimal concentration and dose, elimination and safety were reviewed. Clinical studies were classified according to their study design. The sensitivity, specificity and accuracy of MR arthrography (MRA) were compared with a "gold standard" (arthroscopy, arthrotomy) and other radiological evidence for different joints. RESULTS: Fifty-two clinical studies of the overall 112 studies addressed aspects of diagnostic efficacy of MRA in patients or in healthy volunteers. The shoulder was the most assessed joint (29 of 52 studies). Good (>80%) or even excellent (90-100%) sensitivity, specificity and accuracy were found for MRA in most indications, especially for the shoulder and knee joints and induced extension of rotator cuff lesions, labrum abnormalities and postoperative meniscal tears. Two millimoles per liter has proven to be the best concentration for intra-articular administration of Gd-DTPA. After passive complete diffusion from the joint within 6-24 h, complete and rapid renal elimination takes place after intra-articular injection. Local safety proved to be excellent after intra-articular administration of Gd-DTPA. Regarding systemic tolerance almost no side effects have been reported, but the same safety considerations apply for intra-articular administration of Gd-DTPA as for intravenous injection. CONCLUSIONS: The diagnostic efficacy of intra-articular MRA in most clinical conditions affecting major joints is greater than that of plain MRI. In some diagnostic problems MRA achieves almost the same sensitivity and specificity as the surgical gold standard. Given a sterile application, the intra-articular administration of Gd-DTPA in a concentration of 2 mmol/l prior to MRI is a safe procedure.

Arthrography↗
PubMed2001

Four-dimensional imaging and quantitative reconstruction to analyse complex spatiotemporal processes in live cells.

Live-cell imaging technology using fluorescent proteins (green fluorescent protein and its homologues) has revolutionized the study of cellular dynamics. But tools that can quantitatively analyse complex spatiotemporal processes in live cells remain lacking. Here we describe a new technique--fast multi-colour four-dimensional imaging combined with automated and quantitative time-space reconstruction--to fill this gap. As a proof of principle, we apply this method to study the re-formation of the nuclear envelope in live cells. Four-dimensional imaging of three spectrally distinct fluorescent proteins is used to simultaneously visualize three different cellular compartments at high speed and with high spatial resolution. The highly complex data, comprising several thousand images from a single cell, were quantitatively reconstructed in time-space by software developed in-house. This analysis reveals quantitative and qualitative insights into the highly ordered topology of nuclear envelope formation, in correlation with chromatin expansion - results that would have been impossible to achieve by manual inspection alone. Our new technique will greatly facilitate study of the highly ordered dynamic architecture of eukaryotic cells.

Animals↗
PubMed2001

Enoximone maintains intestinal villus blood flow during endotoxemia.

BACKGROUND: The objective of this study was to determine the effects of a continuous infusion of the phosphodiesterase inhibitor enoximone on mucosal villus blood flow in a normotensive model of endotoxemia. METHODS: Twenty-four anesthetized and ventilated rats underwent laparotomy and a ileal portion was exteriorized and opened by an antimesenteric incision. The ileal segment was fixed on a plexiglass stage with the mucosal surface upward. Microcirculatory parameters were assessed by intravital videomicroscopy. The animals were randomly assigned to receive one of three treatments: infusion of Escherichia coli lipopolysaccharides (LPS, 2 mg/kg/h) without phosphodiesterase inhibitor pretreatment (LPS group); or infusion of LPS with enoximone pretreatment (10 microg x kg(-1) x min(-1), start 30 min before LPS infusion, enoximone group), or infusion of an eqivalent volume of NaCl 0.9% (control group). Macrohemodynamic parameters (MAP, HR) and microhemodynamic parameters of ileal mucosa (mean diameter of central arterioles = DA, and mean erythrocyte velocity within the arterioles = VE) were measured 30 min before and at 0, 60, and 120 min after induction of endotoxemia. Mucosal villus blood flow was calculated from DA and VE. RESULTS: In this normotensive endotoxemia model MAP remained stable in the control and the LPS group but significantly decreased in the enoximone group. The endotoxin-induced decrease of VE and DE of central arterioles of mucosal villi could be prevented. Thus, mucosal villus blood flow did not decrease compared to the LPS group. CONCLUSIONS: Our results indicate that enoximone during an early stage of sepsis contributes to systemic hypotension but prevents mucosal hypoperfusion.

Analysis of Variance↗