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Hydrodynamic consequences of glycolysis: thermodynamic basis and clinical relevance.

Since Warburg's original description of aerobic and anaerobic glycolysis in 1924, the biochemical and molecular bases of glucose metabolism in cells have been characterized. However, its thermodynamic implications have found little attention. Van't Hoff's law of thermodynamics was applied here to describe how glucose metabolism affects intracellular osmotic pressure, hence revealing how glucose metabolism provides cells with osmotic energy as well as chemical energy. Ensuing osmosis-driven movement of free water across membranes affects cell volume and shape, hydration of intracellular components, and interactions of cells with their environment. Comparative analysis of extant data revealed strong evidence for clinically relevant glycolysis-driven effects under hypoxic conditions known to occur in cancer, vascular disease as well as intensive care, including critical and preventable ones affecting treatment effectiveness and thus, clinical outcome. These findings provide the first evidence confirming the existence of glycolysis-driven hydrodynamic effects and suggest that high levels of aerobic and anaerobic glycolysis provide a common biophysical basis in seemingly unrelated medical conditions.

Cell Hypoxia↗

Reduction of spoilage microorganisms in fresh beef using hydrodynamic pressure processing.

Hydrodynamic pressure processing (HDP) was investigated as a technology to reduce spoilage microorganisms found in fresh beef. In two separate studies (studies 1 and 2), retail ground beef and beef roasts were purchased (day 0). The roasts were divided into stew pieces (30 to 40 g). All meat samples, including control samples, were stored at 5 degrees C for 20 h in a plastic film. After storage, designated samples were treated with HDP In study 3, ground beef was treated with HDP (day 0) and stored aerobically (5 degrees C) for 14 days with control samples. Each meat type was vacuum-packaged for HDP (100 g binary explosive, steel shock wave container). The pHs and the aerobic plate counts (log10 CFU/g) were measured on day 0 (studies I and 2) and on days 0, 7, and 14 (study 3) for control samples and for HDP-treated samples. There was no pH difference between control and HDP-treated meat types (studies 1 and 2); HDP reduced bacteria in both meat types in study 1 (2 log) and study 2 (1.5 log) on day 0. In study 3, there was a significant difference (P < 0.05) in pH between control meat (8.2) and HDP-treated meat (5.6) after storage. There was an immediate reduction (1.5 log) of microorganisms following HDP (day 0) and a 4.5-log difference between control samples (9 log) and HDP-treated samples (4.5) after 14 days of storage. With HDP, it is possible to reduce spoilage microorganisms found in or on different meat types (ground beef versus stew pieces), which could extend the shelf life of meat products.

Animals↗

Penetration of surface-inoculated bacteria as a result of hydrodynamic shock wave treatment of beef steaks.

The top surface of the raw eye of round steaks was inoculated with either green fluorescent protein (GFP)-labeled Escherichia coli (E. coli-GFP) or rifampin-resistant E. coli (E. coli-rif). Cryostat sampling in concert with laser scanning confocal microscopy (LSCM) or plating onto antibiotic selective agar was used to determine if hydrodynamic shock wave (HSW) treatment resulted in the movement of the inoculated bacteria from the outer inoculated surface to the interior of intact beef steaks. HSW treatment induced the movement of both marker bacteria into the steaks to a maximum depth of 300 microm (0.3 mm). Because popular steak-cooking techniques involve the application of heat from the exterior surface of the steak to achieve internal temperatures ranging from 55 to 82 degrees C, the extent of bacterial penetration observed in HSW-treated steaks does not appear to pose a safety hazard to consumers.

Animals↗

[Percutaneous mechanical thrombectomy for thrombosed vessels with a hydrolyser (hydrodynamic thrombectomy catheter): clinical experience].

A hydrodynamic thrombectomy catheter was prospectively evaluated for the treatment of thrombosed vessels. Seven patients (7 males: age range from 56 to 82 years; mean age: 79 years) presenting with acute or chronic occlusion of peripheral native arteries (n = 6) and dialysis shunt (n = 1) were treated with the hydrolyser (Cordis, Johnson and Johnson, Japan). Mean occlusion time was 135 days (range: 2-300 days), and mean thrombus length 16 cm (range: 5-20 cm). Removal of the thrombus was successful in five patients (71%), regardless of the length of the thrombus. Mean procedure time was 20 minutes (range: 15-30 minutes). No major complications occurred. Adjunctive thrombolysis was required for persistence of the residual thrombosed distal vessel in one patient. Adjunctive balloon angioplasty was performed in two patients (one native vessel and one dialysis shunt), and stent placement was performed in one patient (dialysis shunt). In two unsuccessful cases, the hydrolyser could not be advanced to the distal side because of the solid thrombus. Therefore, thrombolytic therapy was chosen. However, this therapy failed because the guidewire did not pass within the thrombus. Surgery was performed in these two patients. We conclude from this clinical experience that percutaneous thrombectomy with a hydrolyser is a promising technique for the treatment of thrombosed vessels. Especially in the acute stage of thrombosed occlusion, percutaneous thrombectomy with a hydrolyser is superior to thrombectomy with a Fogarty balloon catheter because of its shorter procedure time and fewer complications.

Acute Disease↗

[Evaluation of major pharmacokinetic parameters of high molecular weight polyethylene oxide using polymer hydrodynamic properties].

The pharmacokinetics of high-molecular-weight polyethylene oxide (HMW PEO)--a parent compound in the polietoks drug--was experimentally studied in cats. A PEO concentration in the blood was determined by measuring a decrease in the hydrodynamic resistance for a blood sample flowing in the turbulent mode via a glass capillary. Variation of the polymer concentration in the blood is described by a single-exponent function with an elimination halftime of T1/2 = 3.15 h. According to the calculation, 99.6% of the initial amount of PEO losses the antiturbulent activity within 24 h.

Animals↗

[Effects of monochromatic light on ocular hydrodynamics].

Effects of green and red optic filters on ocular hydrodynamics was studied. The results indicate that monochromatic green light causes a decrease of the true intraocular pressure, improves intraocular fluid discharge, and decreases Becker's coefficient. Green filters (ZSP) can be used as an additional method for conservative treatment of glaucoma patients.

Adult↗

[Hydrodynamic property of internal airlift loop bioreactor with cells immobilized onto ceramic honeycomb support(IALBR-CICHS)].

An internal airlift loop biorector with cells immobilized onto ceramic honeycomb support(IALBR-CICHS) was developed based on the bubble columns(BC) and airlift(AL) bioreactor by installing a ceramic honeycomb support in the draught tube. Their hydrodynamics were respectively studied by the tracer element to determine their retention time distribution (RTD). Experiment and theory analysis indicated that the IALBR-CICHS had more efficacious reactive volume rate(eta) and less short-circuit rate(lambda) for fluid flow compared with the BC and AL bioreactor.

Bioreactors↗

Hydrodynamic characterisation of ventricular assist devices.

A new mock circulatory system (MCS) was designed to evaluate and characterise the hydraulic performance of ventricular assist devices (VADs). The MCS consists of a preload section and a multipurpose afterload section, with an adjustable compliance chamber (C) and peripheral resistor (Rp) as principal components. The MCS was connected to a pulse duplicator system for validation, simulating a wide range of afterload conditions. Both pressure and flow were measured, and the values of the different components calculated. The data perfectly fits a 4-element electrical analogon (EA). The MCS was further used to assess the hydrodynamic characteristics of the Medos VAD as an example of a displacement pump. Data was measured for various MCS settings and at different pump rates, yielding device specific pump function graphs for water and pig blood. Our data demonstrate (i) flow sensitivity to preload and afterload and (ii) the effect of test fluid on hemodynamic performance.

Equipment Design↗

Comparative hydrodynamic evaluation of bioprosthetic heart valves.

BACKGROUND AND AIM OF STUDY: Pressure gradients across cardiac valve prostheses have been identified as one of the most important performance measures in valve replacement surgery. Specifically in aortic valves, these gradients influence reduction of left ventricular hypertrophy and are postulated to influence long-term survival. The correct choice of replacement valve is hampered by a lack of uniform measures of valve performance. The aim of this study was to compare in-vitro hydrodynamic performance of commercially available bioprosthetic valves under identical test conditions. METHODS: In-vitro steady forward flow and pulsatile flow tests were performed on aortic and mitral bioprosthetic valves in accordance with ISO/FDA guidelines at two different institutions to obtain objective hemodynamic performance measures. Measurements were recorded at various flow rates, flow and pressure to obtain mean pressure gradients and effective orifice areas (EOAs). RESULTS: Wide variation in pressure gradients was found among tested valves of each size. For a given size, differences of 200 to 400% were observed; in general, the valve models' relative rankings in pressure drop were independent of size. CONCLUSION: The Carpentier-Edwards Perimount valve showed superior performance at all sizes tested. While the mean pressure gradients and EOAs reported by each institution differed for a given valve, the performance of valve models relative to each other was similar. The testing of valves under identical conditions is a valuable comparative indicator of valve hemodynamic performance.

Animals↗

[Characteristics of the hydrodynamic and biological properties of flagellar preparations isolated from submerged cultures of S. typhi].

A study was made of the hydrodynamic and biological properties of the flagella from the S. typhi 4446 cultures, isolated by the methods of differential centrifugation, in crude condition and following depolimerization and denaturing by the action of chemical and physical agents. Molecular parameters of the slow and rapid components of the flagella and subunits of the flagellin were compared. The greatest antigenic activity was possessed by the high molecular fraction of the flagella isolated in the 60% sucrose density gradient.

Animals↗

[The hydrodynamics of the superficial cortical nephrons of the rat kidney during a diuretic response].

Diuretic response to administration of mannitol, furozemide, ethaerynic acid, and euphyllinum was invariably followed by a considerable dilation of the lumen of proximal and distal tubular of the kidney surface nephrones. Simultaneously, a considerably reduced flow of the tubular fluid was always observed except after euphyllinum administration, the latter being followed by acceleration of the flow. Questions of interrelationships between the nephrone's hydrodynamic characteristics and the processes of glomerule filtration and tubular reabsorption of the fluid and electrolytes, are discussed.

Aminophylline↗

[Hydrodynamic parameters of native C-reactive protein molecule in a solution].

The hydrodynamic properties of the C-reactive protein in solution (pH 6.8) were studied using quasi-elastic light scattering and size-exclusion liquid chromatography. It was shown that the solution containing the C-reactive protein represents a polydisperse system. The values of the translation diffusion coefficient and the apparent molecular weight of the C-reactive protein in solution at pH 6.8 were determined. The values of the translation diffusion coefficient, molecular weight and the hydration radius obtained suggest that the native pentameric C-reactive protein is the major form of the protein in solution at pH 6.8.

C-Reactive Protein↗

The use of hydrodynamic vortex separators and screening systems to improve water quality.

The paper reviews the evolution of Hydrodynamic Vortex Separators (HDVS) in the context of application as high rate rotary flow separators for achieving water quality improvements to meet with regulatory requirements in Europe and North America. The types of HDVS and their application for the control of wet-weather discharges such as combined sewer overflows (CSOs), sanitary sewer overflows (SSOs) and stormwater are outlined and a number of myths surrounding their use, dispelled. Reference is made to outputs of peer reviewed comprehensive monitoring, evaluation and demonstration projects on pilot and full-scale installations to demonstrate the efficacy and extensive track record of these systems. Recent developments and innovations in HDVS technologies are discussed, focusing on their combined use as solids liquid separators, contact vessels for wastewater disinfection, the incorporation of self-cleansing screening devices for the control of aesthetic pollutants (e.g. floatables) and the use of computational modelling for optimisation.

Disinfectants↗

[The role of the autonomic nervous system in regulating the hydrodynamics of the intact eye].

In cats, the low-molecular indicator: radioactive phosphorus, and the tonography revealed that the local application of acetylcholine accelerates the fluid exchange in the intact eye, considerably facilitating the outflow. Noradrenaline and the threshold stimulation of the cervical sympathetic nerve slow down the intraeye fluid exchange, decreasing the outflow. The data obtained suggest that the neural regulation of the eye hydrodynamics involves, mainly, a direct effect of the vegetative innervation on the eye drainage system.

Acetylcholine↗

Fluid hydrodynamics in submerged and sidestream membrane bioreactors.

As with all membrane processes, turbulence, as promoted by aeration in submerged membrane bioreactors (MBRs) or pumping in sidestream (SS) systems to produce somewhat higher effective cross-flow velocities, increases mass transfer and reduces fouling. This is manifested in an elevated critical flux, the flux at which the membrane permeability is sustained. However, the non-Newtonian nature of the sludge makes precise rheological characterisation difficult. In this study, a calculation of the appropriate hydrodynamics parameters for a SS MBR configuration is presented. Optimisation of the aeration in a submerged MBR system has been attained by defining the minimum air velocity required for Taylor bubble formation.

Bioreactors↗

[Effect of Ca2+ ions on hydrodynamic properties of pentamer and decamer of C-reactive protein in solution].

The molecular mass and sedimentation coefficient of native C-reactive protein in solution were determined by analytical ultracentrifugation in the presence and absence of calcium ions. Pentameric C-reactive protein was shown to be the major macroscopic form of this protein in solution. The removal of calcium ions from solution caused decompaction of the protein accompanied by changes in its hydrodynamic parameters. The sedimentation coefficient s20(0), w of pentameric C-reactive protein in solution containing 2 mM--Ca2+ (6.6S) exceeded that for C-reactive protein in solution containing 2 mM EDTA (6.4S). Analysis of average molecular masses Mw and Mz obtained from sedimentation data demonstrated that the solution of highly purified protein was not homogeneous. As shown by intermolecular crosslinking, the solution also contained the 241-kDa decamer of C-reactive protein (9.5S) as a separate macroscopic form, whose share hardly reached 10% in the presence of 2 mM Ca2+ and increased after removal of calcium ions. The decamers were shown to result from intermolecular association of the pentamers.

C-Reactive Protein↗

Interactive blood simulation for virtual surgery based on smoothed particle hydrodynamics.

In this paper, we propose an interactive method based on Smoothed Particle Hydrodynamics (SPH) to simulate blood as a fluid with free surfaces. While SPH was originally designed to simulate astronomical objects, we gear the method towards fluid simulation by deriving the force density fields directly from the Navier-Stokes equation and by adding a term to model surface tension effects. In contrast to Eulerian grid-based approaches, the particle-based approach makes mass conservation equations and convection terms dispensable which reduces the complexity of the simulation. In addition, the particles can directly be used to render the surface of the fluid. Our method can be used in interactive surgical training systems with models of up to 3000 particles.

Aneurysm↗