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At least 613 records · Page 34Linked to original sources
PubMed1994

Development of indices for determining extracellular fluid sodium and water status in acute diabetic ketoacidosis: possible tools for clinical audit.

The limitation of plasma sodium concentration as an indicator of extracellular hydration status in cases of acute diabetes is well recognized and could lead to individually inappropriate fluid therapy. However, in view of the small analytical and biological variations exhibited by plasma concentrations of protein, water, and sodium in health, we have developed simple laboratory indices that may better describe the extracellular environment. Preliminary data presented here for 20 patients with acute diabetic ketoacidosis admitted as emergencies to Crosshouse Hospital suggest that the type of approach we describe has the potential to supply meaningful therapeutic data to the managing physician and, therefore, merits further study in a clinical setting.

Adult↗
PubMed1994

Numerical analysis of extracellular fluid flow and chemical species transport around and within porous bioactive glass.

Modeling of the physical phenomena present at the biomaterial-tissue interface provides a valuable tool for examining the underlying mechanisms which influence the overall behavior of the implant-host system. Based on histological data from a previous implantation study (E. Schepers, M. De Clercq, P. Ducheyne, and R. Kempeneers, "Bioactive glass particulate materials as a filler for bone lesions," J. Oral Rehab.; 18, 439-452, 1991, Ref. 1) which documented the differentiation of mesenchymal cells to cells expressing the osteoblastic phenotype in porous bioactive glass, a finite element momentum and mass transport model was constructed. In this analysis, the extracellular compositional variations and fluid flow conditions around and within porous bioactive glass granules were determined. Numerical simulations demonstrated that the interstitial fluid flow around these granules (300-360 microns) is viscosity dominated (low Reynolds number flow) and that the fluid inside the granules remains stagnant. This velocity field results in shear stresses proportional to the velocity gradient at the granule-fluid interface outside the particles and no shear stresses inside the particles. A parametric study on the effect of interstitial fluid flow on chemical species (Na+, Ca+2, HPO(4)-2) transport outside the granules revealed three domains. At low velocities (0-0.1 micron/s), the transport of species is diffusion controlled. At intermediate velocities (1.0-10 microns/s), diffusion and convection contribute to the species transport. The concentration of chemical species is nearly uniform at high velocities (100-800 microns/s). For all three cases, the transport of chemical species within the granules is diffusion controlled. The differences in transport mechanisms and interstitial fluid flow conditions lead to variations in concentrations, reaction rates, and shear stresses between the inside and the outside of the glass granules. These differences may influence cellular migration, attachment, differentiation, and the overall response to these bioactive materials.

Animals↗
PubMed1991

Optimum doses of deuterium oxide and sodium bromide for the determination of total body water and extracellular fluid.

A practical approach for determining optimum tracer doses is described for measurements of total body water (TBW) and extracellular water (ECW) based on dilution of deuterium oxide and sodium bromide with respective analyses by nuclear magnetic resonance and anion-exchange chromatography. Using these techniques and plasma concentrations corresponding to adult doses up to 1.5 g kg-1 body weight of deuterium oxide and 0.05 g kg-1 of sodium bromide, the variations of analyses of these tracers, at these respective doses, were calculated. TBW determination with an RSD of less than 2% was found to require administration of 0.4 g kg-1 of deuterium oxide. Because basal concentrations of bromide are quantifiable, the accuracy of the extracellular water determination depends upon the magnitude of the increase in plasma bromide concentration; a sodium bromide dose of 0.01 g kg-1 provides a deviation in the determined ECW volume of approximately 1%.

Body Water↗
PubMed1985

Validation of [57Co]cyanocobalamin as an extracellular fluid marker and measurement of albumin exclusion from the interstitium in the rabbit.

The use of [57Co]cyanocobalamin as an extracellular marker has been validated. Its simultaneous use with 51Cr-labeled erythrocytes and 125I-human serum albumin allows quantitative measurement of tissue water and the fractional exclusion of albumin from the interstitial compartment. The extravascular extracellular spaces of rabbit tissue are lung, 32 +/- 4%; heart, 25 +/- 2%; gut, 24 +/- 4%; and muscle, 13 +/- 1%. The fractional excluded albumin spaces are lung, 0.78 +/- 0.05; heart, 0.37 +/- 0.03; gut, 0.69 +/- 0.05; and muscle 0.58 +/- 0.03. The oversimplification that the extravascular extracellular space is a homogeneous region defined by a small tracer molecule and has the composition of lymph must be reconsidered. Albumin has a vastly different distribution in the interstitial spaces of different organs. Use of the three tracers reported here allows efficient measurement of blood volume, interstitial space, and interstitial albumin exclusion in whole tissues and organs, and thus can lead to further understanding of the in vivo changes occurring in various physiologic and disease states.

Animals↗
PubMed2005

Supraphysiological growth hormone: less fat, more extracellular fluid but uncertain effects on muscles in healthy, active young adults.

OBJECTIVES: To study the effects on body composition after 1 month's administration of supraphysiological doses of growth hormone (GH) in healthy, active young adults with normal GH-IGF-I axis. SUBJECTS AND METHODS: Thirty healthy, physically active volunteers (15 men and 15 women), mean age 25.9 years (range 18-35), participated in this study, designed as a randomized, double-blind, placebo-controlled, parallel study with three groups (n = 10: five men and five women in each group). The groups comprised the following: placebo (P), GH 0.1 IU/kg/day [0.033 mg/kg/day] (GH 0.1) and GH 0.2 IU/kg/day [0.067 mg/kg/day] (GH 0.2). RESULTS: In the pooled group with active GH treatment (n = 20) the results showed significant increases: IGF-I increased by 134% (baseline vs. after 1 month), body weight by 2.7%, fat free mass by 5.3%, total body water by 6.5% and extracellular water (ECW) by 9.6%. Body fat decreased significantly by 6.6%. No significant change in intracellular water was detected. The observed increase in fat free mass by 5.3% was explained by the ECW increase, indicating limited anabolic effects of the supraphysiological GH doses. Changes were noticeable in both genders, although more prominent in the male subjects. Fluid retention symptoms occurred in the majority of individuals. CONCLUSIONS: This is, to our knowledge, the first placebo-controlled trial to show the effects of supraphysiological GH doses on body composition and IGF-I levels in physically active and healthy individuals of both genders; the results indicate limited anabolic effects of GH with these supraphysiological doses. The role of GH as an effective anabolic doping agent is questioned.

Absorptiometry, Photon↗