The effects on arterial haemoglobin oxygen saturation and on shunt of increasing cardiac output with dopamine or dobutamine during one-lung ventilation

Publisher's copy made available with the permission of the publisher © Australian Society of AnaesthetistsTheoretically, if the cardiac output were increased in the presence of a given intrapulmonary shunt, the arterial saturation should improve as the venous oxygen extraction per ml of blood decreases if the total oxygen consumption remains constant. Previous work demonstrated that this was not achieved with adrenaline or isoprenaline as increased shunting negated any benefit from improved cardiac output and mixed venous oxygen content. However, pharmacological stimulation of cardiac output and venous oxygen without any increase in shunt should achieve the goal of improved arterial oxygenation. To test this hypothesis, seven pigs were subjected to one-lung ventilation and infused on separate occasions, with dopamine and with dobutamine in random order to increase the cardiac output. The mixed venous oxygen content, shunt fraction, oxygen consumption and arterial oxygen saturation were measured. With both dopamine and dobutamine there was a consistent rise in venous oxygen content. However, with dopamine, the mean shunt rose from 28% to 42% and with dobutamine, the mean shunt rose from 45% to 59% (both changes P<0.01). With dopamine, the mean arterial oxygen saturation fell by 4.7%, and with dobutamine by 2.9%, but neither fall was statistically significant. It is concluded that any benefit to arterial saturation which might occur from a dopamine- or dobutamine-induced increase in mixed venous oxygen content during one-lung ventilation is offset by increased shunting. During one-lung anaesthesia, there would appear to be no benefit to arterial saturation in increasing cardiac output with an infusion of either dopamine or dobutamine.W. J. Russell, M. F. Jameshttp://www.aaic.net.au/Article.asp?D=200331

Purification and characterization of an extracellular amylase from Lactobacillus plantarum strain A6

Extracellular amylase from #Lactobacillus plantarum$ A6 was purified by fractionated precipitation with ammonium sulphate and by anion exchange chromatography. The homogeneity of the purified fraction was tested by polyacrylamide gel electrophoresis and showed multiple amylase forms. A major form had an estimated molecular weight of 50 kDa. It was identified as an alpha-amylase, with an optimum pH of 5.5, an optimum temperature of 65°C and Km value of 2.38 g l-1 with soluble starch substrate. The enzyme was inhibited by N-bromosuccinimide, iodine and acetic acid. The enzyme activation energy was 30.9 kJ mol-1. (Résumé d'auteur

The effects on increasing cardiac output with adrenaline or isoprenaline on arterial haemoglobin oxygen saturation and shunt during one-lung ventilation

Publisher's copy made available with the permission of the publisher © 2000 Australian Society of AnaesthetistsTheoretically, if the cardiac output were increased in the presence of a given intrapulmonary shunt, the arterial haemoglobin oxygen saturation (SaO2) should improve as the venous oxygen extraction per ml of blood decreases. To test this hypothesis, eight pigs were subjected to one-lung ventilation and adrenaline and isoprenaline infusions used to increase the cardiac output. The mixed venous oxygen, shunt fraction and oxygen consumption were measured. With both adrenaline and isoprenaline, although there was a small rise in mixed venous oxygen content, there was a fall in SaO2. With adrenaline, the mean shunt rose from 48% to 65%, the mean oxygen consumption rose from 126 ml/min to 134 ml/min and the mean SaO2 fell from 86.9% to 82.5%. With isoprenaline, the mean shunt rose from 45% to 59%, the mean oxygen consumption rose from 121 ml/min to 137 ml/min and the mean SaO2 fell from 89.5% to 84.7%. It is concluded that potential improvement in SaO2, which might occur from a catecholamine-induced increase in mixed venous oxygen content during one-lung ventilation, is more than offset by increased shunting and oxygen consumption which reduce SaO2.W.J. Russell, M.F. Jameshttp://www.aaic.net.au/Article.asp?D=200010

Relationship between fork and intestine length in Atlantic bluefin tuna (Thunnus thynnus).

Los datos de longitud a horquilla facilitan información necesaria para las estadísticas de captura, biología de las pesquerías y estudios de población. Sin embargo, en el muestreo de atún rojo no siempre es posible recopilar mediciones de los ejemplares, y los investigadores tienen que recurrir a relaciones biométricas. Mediante una función lineal, se estimó la longitud a horquilla recta (SFL) a partir de la longitud del intestino y se halló una fuerte relación entre estas variables (SFL = 1,58, L de intestino -1,98, r2 = 0,96). Esta función lineal puede utilizarse en futuras estimaciones SFL. Además, lainversa de la inclinación de esta ecuación representa el índice Nikolsky (Ii), que proporciona información sobre hábitos alimentarios y clasifica los peces como carnívoros, omnívoros u herbívoros. Se obtuvo un valor de índice Nikolsky de 0,64, que indica que el atún rojo del Atlántico es un pez carnívoro. Esta observación coincide con estudios anteriores.Versión de editor

Asymptotic Dynamics of Breathers in Fermi-Pasta-Ulam Chains

We study the asymptotic dynamics of breathers in finite Fermi-Pasta-Ulam chains at zero and non-zero temperatures. While such breathers are essentially stationary and very long-lived at zero temperature, thermal fluctuations tend to lead to breather motion and more rapid decay

Breathers in a system with helicity and dipole interaction

Recent papers that have studied variants of the Peyrard-Bishop model for DNA, have taken into account the long range interaction due to the dipole moments of the hydrogen bonds between base pairs. In these models the helicity of the double strand is not considered. In this particular paper we have performed an analysis of the influence of the helicity on the properties of static and moving breathers in a Klein--Gordon chain with dipole-dipole interaction. It has been found that the helicity enlarges the range of existence and stability of static breathers, although this effect is small for a typical helical structure of DNA. However the effect of the orientation of the dipole moments is considerably higher with transcendental consequences for the existence of mobile breathers.Comment: 4pages, 5 eps figure

Nonequilibrium steady state thermodynamics and fluctuations for stochastic systems

We use the work done on and the heat removed from a system to maintain it in a nonequilibrium steady state for a thermodynamic-like description of such a system as well as of its fluctuations. Based on a generalized Onsager-Machlup theory for nonequilibrium steady states we indicate two ambiguities, not present in an equilibrium state, in defining such work and heat: one due to a non-uniqueness of time-reversal procedures and another due to multiple possibilities to separate heat into work and an energy difference in nonequilibrium steady states. As a consequence, for such systems, the work and heat satisfy multiple versions of the first and second laws of thermodynamics as well as of their fluctuation theorems. Unique laws and relations appear only to be obtainable for concretely defined systems, using physical arguments to choose the relevant physical quantities. This is illustrated on a number of systems, including a Brownian particle in an electric field, a driven torsion pendulum, electric circuits and an energy transfer driven by a temperature difference.Comment: 39 pages, 3 figur

Energy Relaxation in Nonlinear One-Dimensional Lattices

We study energy relaxation in thermalized one-dimensional nonlinear arrays of the Fermi-Pasta-Ulam type. The ends of the thermalized systems are placed in contact with a zero-temperature reservoir via damping forces. Harmonic arrays relax by sequential phonon decay into the cold reservoir, the lower frequency modes relaxing first. The relaxation pathway for purely anharmonic arrays involves the degradation of higher-energy nonlinear modes into lower energy ones. The lowest energy modes are absorbed by the cold reservoir, but a small amount of energy is persistently left behind in the array in the form of almost stationary low-frequency localized modes. Arrays with interactions that contain both a harmonic and an anharmonic contribution exhibit behavior that involves the interplay of phonon modes and breather modes. At long times relaxation is extremely slow due to the spontaneous appearance and persistence of energetic high-frequency stationary breathers. Breather behavior is further ascertained by explicitly injecting a localized excitation into the thermalized array and observing the relaxation behavior

Analysis of Ductile Bursting in Pressure Vessels of Texture-Hardening and Filament-Wrapped Materials

Analyses are presented for predicting the strength governed by the plastic tensile instability (PTI) phenomenon in thin-walled cylindrical and spherical pressure vessels constructed of texture- hardening alloys and with or without over-wrapped filaments. These analyses are important in predicting ductile bursting of pressure vessels used in such high-performance applications as high-pressure storage bottles, liquid-propellant tankage, and solid rocket casings. The analyses cover cylindrical pressure vessels subject to any ratio of biaxial stresses. Also means of estimating the effect of finite length is presented. Spherical vessels of texture- hardening material and cylindrical vessels with filaments over wrapped on a texture-hardening metallic substrate are treated as special cases. The analytical results are compared with available experimental results with good success.Yeshttps://us.sagepub.com/en-us/nam/manuscript-submission-guideline