Body Water Content

Stansell and Mojica (1968) have described a procedure for the determination of total body water content of human subjects. They used 11- to 12-g doses of DjO, vacuum sublimation of serum samples, and quantitation of the deuterium by infrared spectroscopy at 2510 cm. The chief advantages given for the procedure were (1) a D2O dose of only 10 ml is required for adult subjects, and (2) the ease of the assay is coupled with satisfactory accuracy and precision. The coefficient of variation based 

Determination of Toxic Gases and Volatile Organic Compounds in Human Beings 

The concentration of the solution to be analyzed and the transmission of the solvent at the wavelength of analysis are factors to be considered in choosing a cell. If the product of the percentage concentration of the sample and the optical path 

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Osmotic diuretics such as mannitol act on the proximal tubule and, in particular, the descending limb of the Loop of Henle — portions of the tubule permeable to water. These drugs are freely filtered at the glomerulus, but not reabsorbed therefore, the drug remains in the tubular filtrate, increasing the osmolarity of this fluid. This increase in osmolarity keeps the water within the tubule, causing water diuresis. Because they primarily affect water and not sodium, the net effect is a reduction in total body water content more than cation content. Osmotic diuretics are poorly absorbed and must be administered intravenously. These drugs may be used to treat patients in acute renal failure and with dialysis disequilibrium syndrome. The latter disorder is caused by the excessively rapid removal of solutes from the extracellular fluid by hemodialysis. 

Mozambique tilapia, Tilapia mossambicus 1100 No deaths in 90 days. Increased growth and body water content disrupted serum electrolytes 23... 

Values for the exchangeable body water content as well as the half-life of tritiated water in some mammalian species that can be applied to the above equation were shown earlier in Table 18.3. If the molecule is likely to or is known to fragment into two major portions, it may be desirable to monitor both fragments by differential labeling (3H and 14C). 

Before passing to a consideration of the results of blood analyses, etc., we may mention body water content, a determination which can be made on the whole bodies of well individuals. By a deuterium... 

This is a bit of a surprise as the patient only weighs 62 kg and therefore has a total body water content of around 40 1 at most. How can an apparent volume of distribution be so much bigger than any physiological volume ... 

Q1 What factors promote the sensation of thirst and how is thirst related to the regulation of body water content ... 

Ethanol absorption is influenced by food intake (which restricts the rate of absorption) the higher the dietary fat content, the slower the time of passage and the longer the process of absorption. First-pass metabolism in the stomach is important. Women absorb and metabolise alcohol differently from men their lower body water content and a lower activity of alcohol dehydrogenase (ADH) in the stomach result in a more rapid and significant absorption. 

Adolph, E.F. (1967) Regulation of water intake in relation to body water content. In Handbook of Physiology, Section 6 Alimentary Canal, Vol. 1, Control of food and water intake (Code, C.F., ed.), p. 163, American Physiological Society, Washington, DC. 

Large doses of mannitol used in treating cerebral edema can alter extracellular fluid volume, osmolality, and composition and can lead under some circumstances to acute renal insufficiency, cardiac decompensation, and other complications (1). The patient s body habitus, age, total body water content relative to body weight, pretreatment plasma sodium concentration and plasma osmolality, and the presence of edema or ascites can influence the degree of extracellular fluid change and the rate of mannitol excretion to a significant degree. 

Skeletal muscle is a major component of body tissue and accounts for 40-50% of the body weight. Skeletal tissue is composed of specialized striated cells, which function to convert chemical energy to mechanical work. Skeletal muscle plays a central role in body metabolism and serves as a source of body heat and a storage depot for energy-rich compounds, protein, and intracellular ions (e.g., potassium). It also contains up to 80% of the body water content. In contrast to cardiac and smooth visceral muscle tissue, skeletal muscle is under voluntary control. 

During most PD modalities, the metabolic waste clearance profile is markedly different from what is observed in HD patients. In patients treated with intermittent HD, the serum concentrations of metabolic wastes exhibit a sawtooth pattern over time. Because CAPD is essentially continuous, a condition similar to a steady state can occur. When the PD dose is well matched to the generation rate of metabolic waste, the serum levels of metabolic waste products fluctuate less over time. Therefore CAPD may represent a more physiologic process that is similar to endogenous renal function. Furthermore, the massive swings in body water content and high peak concentrations of uremic toxins in HD patients are less than optimal. CAPD may therefore be more beneficial for patients with cardiovascular instability. 

Body water and the electrolytes it contains are in a state of constant flux. Wc drink, we eat. we pass urine and wc sweat during all this it is important that wc maintain a steady state. A motor car s petrol tank might hold about 42 litres, similar to the total body water content of the average 70 kg male. If 2 litres were lost quickly from the tank it would hardly regi.steron the fuel indicator. However, if we were to lose the same volume from our intravascular comparimeni w e would be in serious trouble. We are vulnerable to changes in our fluid compartments, and a number of important homeostatic mechanisms... 

The drug is found to be well absorbed orally and thereby survives the first pass through the liver to be effective by the oral administration. Besides, it gets distributed evenly amongst the various tissues having a volume of distribution (v/ ) much higher than the total body water content. However, in the CSF the concentration of metabolites attains almost 150% of that normally present in plasma. It has been observed that the biotransformation usually takes place throughout the body the half-life is nearly 15 minutes, and the half-lives of the metabolites are 48 hour. 

Cholesterol esters and triglycerides have been determined in serums by infrared methods. Biliary and renal calculi ate quite readily analyzed from infrared spectra. Sometimes it is necessary to determine body water content, and this can be done by the use of DjO, and quantitating the deuterium by means of infrared spectroscopy. 

The total body water content increases in patients with severe protein malnutrition. The increase involves both the extracellular fluid, in which the water content may rise up to 400 ml/kg compared to 250 ml/kg in normal individuals, and in the intracellular fluid, in which the water content may reach values above 80%, compared to the normal 67% values in normally fed individuals. Fluid accumulation in the extracellular tissues leads to edema. The severity of the edema may be masked somewhat by the loss of body solids and fats. However, in the later stages of the disease, edema becomes obvious. The edema fluid is not distributed uniformly throughout the body of the victim—swelling usually starts in the inferior limbs, probably as a result of gravity and deficient circulation. The back of the hand and the face are frequently swollen. A patient with kwashiorkor— particularly an older patient— may have edema in the lower part of the body and be dehydrated in the upper part. In younger children, this does not occur because the upright position is not maintained constantly and does not play such an important role in the accumulation of fluid in the inferior limbs. The pathogenesis of the edema in protein deficiency is discussed in the section on body fluids. 

The reduced water content leads to hyperosmolarity, which affects renal function two ways. It stimulates water resorption or ADH secretion and increases electrolyte excretion. Depending upon the water intake, this latter adaptation may maintain homeostasis, but body water content continues to drop. In addition to its normal load of electrolytes, the kidney is forced to excrete an amount of electrolyte sufficient to restore normal osmolarity. The increased rate of electrolyte excretion has consequences that are important for the progress and therapy of the dehydration syndrome. First, the amount of electrolytes excreted by the kidney exceeds the concentration power, and, despite dehydration, more water is lost in the urine to dilute the electrolytes. Second, the total concentration of electrolytes in the blood drops below normal values. Consequently, if plain water is administered to dehydration victims, hyposmolarity ensues. The hyposmolarity blocks ADH secretion and, as a result, water diuresis follows and the patient loses the benefit... 

Fluid supplementation has to be considered carefully because the relative body water-content is age-related and highest in premature infants. The amount of water provided by the nutrition solution and the water used for the dissolution of medicines should not exceed the total need for water. Thereby, often highly concentrated nutrition admixtures with low final volume are to be administered. 

Holleman, D. F., and R. A. Dieterich. 1973. Body water content and turnover in several species of rodents as evaluated by the tritiated water method. J. Mammal. 54(2) 456-465. 

First, it has been shown that the base impedance correlates with the fluid content of the body, and with modified equations the body water content can be ealculated. The assessment of TBW or the thoracic fluid content is one way to detect lung edema in heart failure patients. Second, the morphology of the ICG signal is similar to a human ICG which allows the extraction of established characteristic points and allows the calculation of LVET, SV and CO. CO trends are similar but CO is underestimated by calculations using bioimpedance. Hence, algorithms to calculate SV have to be adapted because of different signal amplitudes of ICG and impedance. 

The systemic adaptation mechanisms in this rat model resemble those of humans adapting to high altitude (28-30), except that rat hematocrit is much more elevated than the human. The effect of hypoxia on body weight is also similar to human adaptations in high altitude (31), which is thought to be due to decreased body water content (32). 

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