Sodium requirement of adult cats for maintenance based on plasma aldosterone concentration.
The sodium requirement of adult cats for maintenance was determined using a randomized block design of eight dietary sodium treatments (0.1, 0.4, 0.5, 0.66, 0.8, 1.2, 1.6 or 2.0 g Na/kg in a casein-lactalbumin-based purified diet) administered for periods of 4 wk. A total of 35 adult specific-pathogen-free domestic shorthaired cats (26 males and 9 females, 1.5-3 y of age) was given an equilibration diet (2 g Na/kg) for 14 d before assignment (or reassignment) to the treatments. A total of 12 cats (8 males, 4 females) was randomly assigned to the lowest six levels of sodium, and four cats to the highest two sodium levels. Cats consuming the diet containing 0.1 g Na/kg had significantly elevated aldosterone concentration in plasma, and packed cell volume. In addition, these cats exhibited anorexia, body weight loss, reduced urinary specific gravity and sodium excretion, and had a negative sodium balance. However, adult cats did not develop polydypsia and polyuria reported in sodium-deficient kittens. Cats given the diet containing 0.66 g Na/kg did not have an increased packed cell volume, but aldosterone concentration in the plasma was significantly elevated. However, cats given diets containing >/=0.8 g Na/kg had plasma aldosterone concentrations +info)
Four-component model of body composition in children: density and hydration of fat-free mass and comparison with simpler models.
BACKGROUND: Body composition in children is generally measured by 2-component (2C) models, which are subject to error arising from variation in fat-free mass (FFM) composition. The 4-component (4C) model, which divides body weight into fat, water, mineral, and protein, can overcome these limitations. OBJECTIVE: The aims of our study were to 1) describe 4C model data for children aged 8-12 y; 2) evaluate interindividual variability in the hydration, bone mineral content, and density of FFM; 3) evaluate the success with which 2C models and bedside techniques measure body composition in this age group with use of the 4C model as a reference. DESIGN: Dual-energy X-ray absorptiometry, underwater weighing, deuterium dilution, bioelectrical impedance analysis, and anthropometry were used to determine body composition in 30 children. The contribution of methodologic error to the observed variability in the hydration and density of FFM was evaluated by using propagation of error. RESULTS: Mean (+/-SD) FFM density and hydration were 1.0864+/-0.0074 kg/L and 75.3+/-2.2%, respectively, and were significantly different from adult values (P < 0.02). Relative to the 4C model, deuterium dilution and dual-energy X-ray absorptiometry showed no mean bias for fatness, whereas underwater weighing underestimated fatness (P < 0.025). Fatness determined by using skinfold-thickness and bioelectrical impedance analysis measurements along with published equations showed poor agreement with 4C model data. CONCLUSIONS: Biological variability and methodologic error contribute equally to the variability of FFM composition. Our findings have major implications for bedside prediction methods used for children, traditionally developed in relation to underwater weighing. (+info)
Metabolic production of amphetamine following multidose administration of clobenzorex.
The interpretation of urine drug-testing results can have important forensic and legal implications. In particular, drugs that are metabolized to amphetamine or methamphetamine or both pose significant concerns. In this study, clobenzorex, an anorectic drug that is metabolized to d-amphetamine, was administered to five subjects. Each subject took 30 mg daily for seven days, and individual urine samples were collected ad lib for 14 days beginning on the first day the drug was administered. Urine pH, specific gravity, and creatinine values were determined for each sample. Gas chromatography-mass spectrometry (GC-MS) was used to determine the excretion profile of amphetamine and clobenzorex using a standard procedure for amphetamines with additional monitoring of ions at m/z 118, 125, and 364 for the detection of clobenzorex. Peak concentrations of amphetamine were found at 82 to 168 h after the first dose and ranged from approximately 2900 to 4700 ng/mL amphetamine. The use of a regioisomer (3-Cl-benzylamphetamine) as internal standard allowed for accurate quantitation of the parent drug. Peak concentrations of clobenzorex were found at 50 to 120 h after the first dose and ranged from approximately 8 to 47 ng/mL clobenzorex. However, in many samples, clobenzorex was not detected at all. This analysis revealed that the metabolite, (amphetamine) is present in much higher concentrations than the parent compound, clobenzorex. Yet even at peak amphetamine concentrations, the parent was not always detected (limit of detection 1 ng/mL). Thus, in the interpretation of amphetamine-positive drug-testing results, the absence of clobenzorex in the urine sample does not exclude the possibility of its use. (+info)
Localization of sterically stabilized liposomes in Klebsiella pneumoniae-infected rat lung tissue: influence of liposome characteristics.
Sterically stabilized liposomes are able to localize at sites of infection and could serve as carriers of antimicrobial agents. For a rational optimization of liposome localization, the blood clearance kinetics and biodistribution of liposomes differing in poly(ethylene glycol) (PEG) density, particle size, bilayer fluidity or surface charge were studied in a rat model of a unilateral pneumonia caused by Klebsiella pneumoniae. It is shown that all liposome preparations studied localize preferentially in the infected lung compared to the contralateral non-infected lung. A reduction of the PEG density or rise in particle size resulted in a higher uptake by the mononuclear phagocyte system, lower blood circulation time and lower infected lung localization. Differences in bilayer fluidity did not affect blood clearance kinetics or localization in the infected lung. Increasing the amount of negatively charged phospholipids in the liposome bilayer did not affect blood clearance kinetics, but did reduce localization of this liposome preparation at the site of lung infection. In conclusion, the degree of localization at the infected site is remarkably independent of the physicochemical characteristics of the PEG liposomes. Substantial selective liposome localization can be achieved provided that certain criteria regarding PEG density, size and inclusion of charged phospholipids are met. These properties seem to be a direct consequence of the presence of the polymer coating operating as a repulsive steric barrier opposing interactions with biological components. (+info)
Serial magnetic resonance imaging of rat brain after induction of renal hypertension.
BACKGROUND AND PURPOSE: Hypertension is a major risk factor for ischemic and hemorrhagic stroke and may also cause more chronic and subtle brain injury. Progressive brain changes in a rat model of renal hypertension have been assessed to better understand the pathogenesis of hypertensive brain damage. METHODS: Young adult rats were made hypertensive by partial occlusion of both renal arteries. MR images of brain were obtained weekly, and histopathological outcome was assessed. A separate group of rats was used to measure brain specific gravity and Evans blue dye content as an indicator of extravasation. RESULTS: Rats developed maximal mean systolic blood pressures of 173 to >300 mm Hg, reaching a plateau in 6 to 8 weeks. Rats whose mean systolic pressure never exceeded 210 mm Hg never had brain lesions, while rats whose mean systolic pressure exceeded 276 mm Hg consistently developed brain lesions. Brain T2 values increased with increasing blood pressure. Lesions seen on MRI corresponded to those seen histologically. MRI also demonstrated transient brain expansion, probably due to diffusely increased water content, and rarely demonstrated focal cortical edema, which had no histological correlate. These transient phenomena, as well as hemorrhagic and ischemic infarcts, occurred mainly during the phase of climbing blood pressure and early stages of stable hypertension. CONCLUSIONS: Serial MRI reveals aspects of hypertensive brain disease that cannot be studied by histological examination alone. The observed phenomena are likely related to loss of autoregulation and/or blood-brain barrier integrity. Breach of blood vessel integrity is less likely once the vessels become accustomed to high pressures. (+info)
Clinical significance and evaluation of proteinuria in NIDDM patients.
The proteinuria may reach massive proportions resulting in the nephrotic syndrome. Early and simple diagnostic may prevent further complications. Attempts are made to correlate a simple parameters like pH, specific gravity, excretion of reducing sugar and protein profile on SDS-PAGE, an advanced technique. The pH ranged between 5.7 to 9. However, specific gravity of the urine showed significant increase from 1.000 to 1.088 and has linear relation with percentage of sugar (0.2 to 2 gm) and protein banding 1 to 5 on SDS-PAGE. (+info)
Effect of norepinephrine and fluid administration on pulmonary extravascular water volume in dogs.
The effects of norepinephrine-induced vasoconstriction on pulmonary extravascular water volume (PEWV) and central volume were studied before and after intravenous volume expansion with 5% dextrose and water (20 ml/kg body weight). PEWV was measured by double isotope dilution and gravimetric analysis and assessed by electron photomicrography. Comparisons were made with saline-treated control dogs. Thirty-six dogs were studied after they had been anesthetized with sodium pentobarbital. PEWV determined by indicator dilution increased during norepinephrine infusion, especially after volume expansion; in contrast, PEWV in control dogs was constant despite similar increases in pulmonary arterial and left atrial pressures. However, measurements of PEWV by gravimetric analysis and inspection of electron photomicrographs failed to reveal extravascular accumulation of water in vasoconstricted dogs. Thus, it was concluded that the increased PEWV measured by indicator dilution in norepinephrine-treated dogs compared with that in saline-treated dogs reflects more complete perfusion of pulmonary capillaries and access of the diffusible indicator to additional lung tissues and spaces. Improved capillary filling presumably is attributable to peripheral vasoconstriction and redistribution of blood into the thorax. PEWV determined by gravimetric analysis in dogs that had had open-chest procedures for lung biopsy and electron photomicrography was significantly less than that in dogs with their chests closed throughout the experiments. Although the mechanism for the water loss in unknown, the difference must be recognized when the results from various types of experiments are compared. (+info)
Acoustic field assisted enhanced demixing of aqueous two-phase systems.
Aqueous two-phase extraction has been recognized as a versatile downstream processing technique for the recovery of biomolecules. A major deterrent to its industrial exploitation is the slow demixing of the two aqueous phases after extraction, due to their similar physical properties. A method to decrease the demixing times of these systems, employing a travelling acoustic wave field, is reported. The effects of phase composition and microbial cells on demixing in a polyethylene glycol/potassium phosphate two-phase system are studied in detail. As phase composition increased, demixing time decreased gradually. Phase volume ratio was found to have a significant effect on demixing time at low phase compositions. However, at intermediate and high phase compositions, only a small effect on demixing time was observed. The effect of phase composition and volume ratio on demixing behavior was explained based on the droplet size of the dispersed phase, which is the resultant effect of the physical properties of the phases. At all the phase compositions studied, the acoustically assisted process decreased the demixing time by 17-60% when compared to demixing under gravity alone. Increasing the cell concentration increased the demixing time markedly in case of yeast cells. However, it remained practically constant in the case of Lactobacillus casei cells. Application of an acoustic field reduced the demixing times up to 60% and 40% in the case of yeast and L. casei cells, respectively. Visual observations indicated that ultrasonication caused mild circulation currents in the phase dispersion enhancing droplet-droplet interaction, which in turn enhanced the rate of coalescence, eventually resulting in an enhanced demixing rate. (+info)