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O/I Ratio (i + ratio)
Selected AbstractsBeam-size effects in radiation damage in insulin and thaumatin crystalsJOURNAL OF SYNCHROTRON RADIATION, Issue 3 2005A. Wagner Cryocooled insulin and thaumatin crystals were irradiated in a series of alternating data collections and high-dose-rate exposures using either a vertically focused or vertically defocused beam. The main result is that the radiation damage is limited to the exposed region, which can be explained by the short range of the photoelectrons and the Auger electron cascade produced by light elements. Consequently, the unexposed angular range provides significantly improved data quality and electron density compared with previously exposed angular wedges of the crystal when a vertically focused beam is used, while no differences are observed between a fresh wedge and an exposed region for the vertically defocused beam. On the other hand, the focused beam provides higher I/,I ratios at high resolution than homogeneous sample illumination but also causes more rapid sample deterioration. [source] Percutaneous transtracheal emergency ventilation with a self-made device in an animal modelPEDIATRIC ANESTHESIA, Issue 10 2007RAIK SCHAEFER Summary Background:, Special equipment for emergency percutaneous transtracheal ventilation is often not immediately available. We used a self-made device consisting of a three-way stopcock connected between a G-15 transtracheal airway catheter and an oxygen supply in a simulated 'cannot intubate, cannot ventilate' scenario and tested the hypothesis that the effectiveness of the device depends on the body weight of the experimental animals. Methods:, With approval of the local animal protection committee, two groups of six pigs each with a body weight of 21 ± 2 and 36 ± 6 kg, respectively, were tracheally intubated and mechanically ventilated after induction of anesthesia. Hemodynamic monitoring included cardiac output and arterial, central venous and pulmonary artery pressures. An emergency transtracheal airway catheter was inserted into the trachea and a situation of partial expiratory airway obstruction was created. Each animal was ventilated for 15 min via the transtracheal airway catheter with the self-made device (FiO2 1.0 at an oxygen flow of 15 l·min,1; respiratory rate of 60 min,1; I/E ratio approximately 1 : 1). Results:, Whereas satisfactory oxygenation was achieved in all animals, sufficient ventilation was obtained only in the lightweight animals. Conclusions:, Adequate oxygenation could be provided by jet-like transtracheal ventilation with a simple self-made device using easily available materials. Sufficient ventilation depends on the body weight of the animals. [source] Effects of long-term vardenafil treatment on the development of fibrotic plaques in a rat model of Peyronie's diseaseBJU INTERNATIONAL, Issue 3 2006MONICA G. FERRINI OBJECTIVES To determine whether the phosphodiesterase-5 (PDE5) inhibitor, vardenafil, given orally and in different regimens, has a similar effect to that of the PDE5 inhibitor sildenafil, which prevented the development of a Peyronie's disease (PD)-like plaque formation induced by injecting transforming growth factor ,1 (TGF-,1) into the tunica albuginea of the rat. MATERIALS AND METHODS Vardenafil was given to male rats (eight per group) either in the drinking water or as an oral instillation once daily, at ,,1 and ,,3 mg/kg/day for 45 days after one injection with TGF-,1 into the tunica albuginea, as an ,early preventive' treatment for TGF-,1-induced formation of a PD-like plaque. Other groups received the two doses of vardenafil only in the drinking water, starting with a well-formed plaque, for 42 days (,late, therapeutic' administration). Sections of penile tissue were stained histochemically or immunohistochemically, followed by quantitative image analysis for collagen/smooth muscle and collagen III/I ratios, myofibroblast content (,-smooth muscle actin), TGF-,1 expression, and apoptotic index. RESULTS Preventative treatment with vardenafil at the higher dose (both continuous and once-daily treatments) reduced the collagen/smooth muscle and collagen III/I ratios, and the numbers of myofibroblasts and TGF-,1-positive cells, and selectively increased the apoptotic index in the PD-like plaque. The lower dose was less effective, When vardenafil was given continuously in the drinking water for 41 days after the PD-like plaque was formed, there was only a partial reduction of the plaque. CONCLUSIONS Long-term oral treatment with vardenafil slows and reverses the early stages of an experimental PD-like plaque in the rat, and might ameliorate a more advanced plaque. [source] Insulin and contraction increase nutritive blood flow in rat muscle in vivo determined by microdialysis of l -[14C]glucoseTHE JOURNAL OF PHYSIOLOGY, Issue 1 2007John M. B. Newman In the present study, a mathematical model using the microdialysis outflow: inflow (O/I) ratio of the novel analogue l -[14C]glucose has been developed which allows the calculation of the nutritive (and non-nutritive) flow in muscle as a proportion of total blood flow. Anaesthetized rats had microdialysis probes carrying l -[14C]glucose inserted through a calf muscle group (tibialis/plantaris/gastrocnemius). The nutritive fraction of total blood flow was determined under basal conditions and in response to contraction (electrical field stimulation), insulin (hyperinsulinaemic euglycaemic clamp with 10 mU min,1 kg,1 insulin) or saline control from limb blood flow and the microdialysis O/I ratio of l -[14C]glucose. Both contraction and insulin infusion decreased the O/I ratio of l -[14C]glucose and increased total limb blood flow. Calculations based on mathematical models using l -[14C]glucose O/I and limb blood flow revealed that during basal conditions, the nutritive fraction of total flow was 0.38 ± 0.06, indicating that basal flow was predominantly non-nutritive. Contraction and insulin increased the nutritive fraction to 0.82 ± 0.24 (P < 0.05) and 0.52 ± 0.12 (P < 0.05). Thus the increase in limb blood flow from insulin was fully accommodated by nutritive flow, while contraction increased nutritive flow at the expense of non-nutritive flow. This novel method using microdialysis and the O/I ratio of l -[14C]glucose allows the determination of the nutritive fraction of total flow in muscle as well as the proportion of total flow that may be redistributed in response to contraction and insulin. [source] Is the historical war against wildlife over in southern Europe?ANIMAL CONSERVATION, Issue 3 2009A. Martínez-Abraín Abstract Most southern European regions have experienced a rapid economical change during the last decades, moving from a historical economy based on agriculture to a society based on industry and technology. We test here whether causes of admission of birds admitted to a large southern European rehabilitation centre, during a 14-year period (1994,2007), reflect these socio-economical changes. Specifically, we estimated the trends in the number of birds admitted to the centre by shooting (S) over the number of birds admitted due to impacts caused by infrastructures (I), for the 10 most commonly admitted species with complete time series available. Species were grouped in three groups following ecological traits: raptors (diurnal and nocturnal) and aquatic birds. Trends were estimated by means of the slope of a linear regression of the log-transformed S/I ratio over time, which provided the finite population growth rate (,) and its 95% confidence intervals. We used the ratio to prevent possible biases caused by changes in wild population densities over the years. We conclude that the overall trend in the S/I ratio, as well as the trends for all three bird groups considered, were negative, and indicated a c. 10% annual reduction in the number of birds admitted by shooting in relation to those admitted by infrastructure-related injuries. Causal relationships were analysed by means of Poisson regressions on absolute numbers. Importantly we show that despite the direct historical war against wildlife seems to be coming to an end in southern Europe, impact to wildlife continues in an indirect way, as collateral damages caused by our post-industrial way of life. So the overall scenario is most likely not one of improved conservation status in southern Europe, but rather one of shifting ways of impacting wildlife in parallel with socio-economic changes. [source] Long-term effects of porcine small intestine submucosa on the healing of medial collateral ligament: A functional tissue engineering studyJOURNAL OF ORTHOPAEDIC RESEARCH, Issue 4 2006Rui Liang Abstract Porcine small intestinal submucosa (SIS) was previously shown to enhance the mechanical properties of healing medial collateral ligaments (MCL), and the histomorphological appearance and collagen type V/I ratio were found to be close to those of normal MCL. We hypothesized that at a longer term, 26 weeks, SIS could guide a better organized neo-ligament formation, increasing mechanical properties and increasing collagen fibril diameters mediated by a reduction in collagen type V. A 6 mm gap injury in the right MCL was surgically created in 38 rabbits, while the contralateral intact MCL served as a sham-operated control. In half the animals, a strip of SIS was sutured onto the severed ends. In the other half, no SIS was applied. The cross-sectional area (CSA) was determined with a laser micrometer system. The femur,MCL,tibia complex was mechanically tested in uniaxial tension. Histomorphology was determined through H&E and immunofluorescent staining and transmission electron microscopy (TEM). Sodium-dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) was used to determine collagen type V/I ratio. SIS-treated MCLs displayed a 28% reduction in CSA, a 33% increase in tangent modulus, and a 50% increase in tensile strength compared with the nontreated group (p,<,0.05). TEM showed groups of collagen fibrils with larger diameters in the SIS-treated ligaments in comparison with uniformly small fibrils for the nontreated group. H&E staining showed more densely stained collagen fibers in the SIS-treated group aligned along the longitudinal axis with more interspersed spindle-shaped cells. Immunofluorescent staining showed less collagen type V signals, confirmed by a 5% lower ratio of collagen type V/I compared with the nontreated controls (p,<,0.05). The findings extend the shorter term 12-week results, and support the potential of porcine SIS as a bioscaffold to enhance ligament healing. © 2006 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res [source] | |||||||||||||