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PubMedDate not supplied

Measurement of plasma colloid osmotic pressure in normal thoroughbred neonatal foals.

A normal plasma colloid osmotic pressure (COP) interval was established for foals and compared to values for adult horses. Plasma samples were obtained from 38 Thoroughbred foals that had normal findings on postfoaling examination and 10 healthy Thoroughbred adult horses. Samples were analyzed using a commercially available colloid osmometer. Fifty samples were obtained from 38 foals. Twelve foals had 2 samples taken, 1 during the 1st 24 hours of life and the 2nd between 24 and 72 hours of life. For foals with 2 samples, only 1 randomly selected value was used in group analysis. Total plasma protein, albumin, and globulin concentrations were measured on all samples from foals. The mean measured plasma COP for foals was 18.8 +/- 1.9 mm Hg for the 38 samples analyzed. Measured plasma COP did not differ significantly over the time period examined for either the 12 paired samples (P = .13) or with regression analysis of the 38 samples (P = .13). Calculation of mean COP, based on previously published quadratic equations using total protein, albumin, and globulin concentrations, underestimated mean measured foal COP values except for when total protein measured by refractometer was used in the Landis-Pappenheimer equation. In conclusion, the plasma COP interval (95% CI: 15.0 mm Hg, 22.6 mm Hg) obtained for healthy foals in this study was found to be lower than that of healthy adult Thoroughbreds (20.6 +/- 0.7 mm Hg, P = .006).

Animals↗
PubMedDate not supplied

Serum-effusion albumin gradient in dogs with transudative abdominal effusion.

A prospective clinical study in dogs with transudative abdominal effusions examined the clinical usefulness of the serum albumin-effusion albumin (SA-EA) gradient. In humans, the SA-EA gradient facilitates classification of abdominal effusion, with a gradient > or = 1.1 indicating the presence of portal hypertension. Gradient values proved useful for predicting therapeutic response to sodium restriction and diuresis in humans. Of 49 dogs evaluated, 25 had hepatobiliary disease (group 1) and 24 had other nonhepatobiliary conditions (group 2). Portal hypertension was clinically suspected in 24 of 25 dogs in group 1 and in 15 of 24 dogs in group 2. A broad range of SA-EA gradients was found. A gradient > or = 1.1 was found in 22 of 25 (88.0%) dogs with liver disease and in 14 of 24 (58.3%) dogs with other disorders. The median SA-EA gradient was higher in group 1 than in group 2, with values of 1.4 (range, 0.7-3.1) and 1.1 (range, 0.3-2.6), respectively (P < .04). Considerable overlapping of SA-EA gradients occurred between groups and among dogs with diverse conditions such that gradient values could not distinguish dogs with hepatobiliary disease from dogs with other conditions. The overall diagnostic accuracy of the SA-EA gradient in predicting portal hypertension in dogs with and without hepatobiliary disease (69.4%) exceeded that of hypoalbuminemia (57.1%). These findings suggest that portal hypertension is a predominant force in formation of transudative abdominal effusion in dogs with hepatobiliary disease and in dogs with other disorders. Whether the SA-EA gradient can be used to guide therapeutic mobilization of effusion in dogs remains to be proved.

Animals↗
PubMed2005

Optical properties of Alexa 488 and Cy5 immobilized on a glass surface.

The absorption and emission spectra were measured for Cy5 and Alexa 488 fluorophores confined on a glass surface. The data were obtained using fluorometry and spectroscopic ellipsometry. Red shifts of the surface-immobilized fluorophore absorption spectra relative to the fluorophore spectra in aqueous solution were observed using both methods. We interpret these red shifts in terms of a change in the polarizability and polarity of the effective solvent. A formula is given that can be used to estimate expected shifts in absorption and emission maxima for surface-immobilized fluorophores. Spectroscopic ellipsometry measurements provide identification of the fluorophores confined on a glass surface. These results suggest that the design of microarray detection systems should be based on the optical properties of fluorophores attached to the surface and not on the optical properties of fluorophores in solution.

Absorption↗
PubMed2002

Comparison of refractometers and test endpoints in the measurement of serum protein concentration to assess passive transfer status in calves.

OBJECTIVE: To evaluate 3 refractometers for detection of failure of passive transfer (FPT) of immunity in calves, and assess the effect of refractometric test endpoints on sensitivity, specificity, and proportion of calves classified correctly with regard to passive transfer status. DESIGN: Prospective study. ANIMALS: 90 calves. PROCEDURE: Blood samples were obtained from calves that were < 10 days old. Serum IgG concentration was determined by use of a radial immunodiffusion assay. Accuracy of 3 refractometers in the prediction of serum IgG concentration was determined by use of standard epidemiologic methods and a linear regression model. RESULTS: At a serum protein concentration test endpoint of 5.2 g/dL, sensitivity of each refractometer was 0.89 or 0.93, and specificity ranged from 0.80 to 0.91. For all refractometers, serum protein concentration test endpoints of 5.0 or 5.2 g/dL resulted in sensitivity > 0.80, specificity > 0.80, and proportion of calves classified correctly > 0.85. Serum protein concentrations equivalent to 1,000 mg of IgG/dL of serum were 4.9, 4.8, and 5.1 g/dL for the 3 refractometers. CONCLUSIONS AND CLINICAL RELEVANCE: The refractometers, including a nontemperature-compensating instrument, performed similarly in detection of FPT. Serum protein concentration test endpoints of 5.0 and 5.2 g/dL yielded accurate results in the assessment of adequacy of passive transfer; lower or higher test endpoints misclassified larger numbers of calves.

Animals↗
PubMed1989

Fluid distribution in pork, measured by x-ray diffraction, interference microscopy and centrifugation compared to paleness measured by fiber optics.

Moderately PSE (pale, soft, exudative) and moderately DFD (dark, firm, dry) pork was examined by x-ray diffraction for interfilament separation, by differential interference contrast microscopy for interfiber area, and was centrifuged to measure water holding capacity (WHC). Internal reflectance spectra were measured by fiber optics. For PSE to DFD pork, filament separation ranged from 39 to 48 nm, interfiber area from 42 to 3%, and WHC from 49 to 64%, respectively. The correlation of reflectance with interfilament separation varied considerably with wavelength (reaching r = -.83 at 680 nm, P less than .005). The correlation of reflectance with interfiber area was more uniform across the spectrum (reaching r = .90 at 450 nm, P less than .005), as was the correlation of reflectance with WHC (reaching r = -.80 at 400 nm, P less than .005). At 24 h postmortem, fiber-optic spectrophotometry may be used as a rapid, nondestructive method to predict WHC and potential fluid losses from commercial pork with a moderate range from PSE to DFD. Interfiber area was correlated negatively with filament lattice area and WHC, but no significant correlation was found between filament lattice area and WHC. Filament separation was decreased only slightly by centrifugation. These results indicate that at 24 h postmortem the extra fluid released from PSE pork already has been lost from the myofilament lattice and is awaiting release from compartments downstream such as interfiber and interfascicular spaces.

Animals↗
PubMed1986

Refractive index of meibomian and other lipids.

The refractive indices of human and rabbit meibomian secretions, and of several natural lipid mixtures and eye ointments, have been measured as a function of temperature and wavelength. A value of 1.482 was found for meibomian oil at typical eye surface temperature, but varies in humans between ca. 1.46 and 1.53 over the visible spectrum.

Animals↗
PubMed1980

Critical light reflection at a plastic/glass interface and its application to foot pressure measurements.

The necessary properties of plastic materials for use in a method of foot pressure distribution measurements have been assessed, and the mechanisms in operation at an illuminated plastic to glass interface underload have been investigated. A hypothesis is given of the physical principles upon which the operation of this technique is based and it is shown that a calibrated analysis of both the static and dynamic distribution of pressure under the foot is possible by this technique.

Biomechanical Phenomena↗
PubMed1987

Some new methods for affixing sections to glass slides. II. Organic-solvent based adhesives.

Adhesion of various organic-solvent based adhesives to glass slides could be greatly improved by first priming the slide with a copolymer of allyl methacrylate and methacryloxypropyltrimethoxysilane. The use of different solvents and types of adhesives with these slides is discussed. Cellulose nitrate in different esters of acetic acid proved to be an effective adhesive for varied sections at room temperature and in the cryostat. Carbowax sections as a special case preferably were affixed with polyisobutylene in petroleum ether. Most of the attachments formed resisted even boiling water.

Adhesiveness↗
PubMed1997

Detection of residual polyethylene glycol derivatives in pyridoxylated-hemoglobin-polyoxyethylene conjugate.

Purified hemoglobin solutions have been shown to cause renal toxicity in animals. Safe use of hemoglobin based therapeutics in humans requires modification of the hemoglobin molecule to prevent this toxicity. Hemoglobin modification may be accomplished by crosslinking the dimers within the hemoglobin tetramer or by derivatization of the alpha and/or beta subunits such that their size and/or charge prevents filtration by the glomeruli. Pyridoxylated hemoglobin polyoxyethylene conjugate (PHP) consists of hemoglobin molecules modified with alpha-carboxymethyl, omega-carboxymethoxy polyoxyethylene (POE). We have developed a high performance liquid chromatography-based (HPLC) method which can quantitate residual POE at levels of 0.1 mg/ml or greater. The detection of POE at this level of sensitivity requires the use of an evaporative light scattering detector (ELSD). A differential refractometer may also be used for POE detection, however the limit of quantitation for this detector is approximately 10 fold greater than that observed for the evaporative light scattering detector, resulting in a reduction in sensitivity. The successful use of this method requires sample deproteination using trichloroacetic acid. The reliability of the method has been demonstrated by spike recovery, precision, and reproducibility studies in PHP and buffer solutions.

Animals↗
PubMed1996

Micellization and solubilization behavior of sucrose laurate, a new pharmaceutical excipient.

The micellization and solubilization properties of sucrose laurate have been investigated. Solubilization experiments showed that numerous poorly water-soluble drug substances could be solubilized by aqueous sucrose laurate solutions; the solubilization was uncomplicated and the maximum solubilizate concentration was high. Laser light scattering investigations proved that solutions containing pure sucrose monolaurate formed spheroidally shaped micelles with a hydrodynamic radius of 29.2 A, which behaved like ideal particles, showing no solute-solute interactions. Surprisingly, the hydrodynamic radii of the sucrose monolaurate micelles were hardly changed by the introduction of 0.20% cyclosporin-A. The addition of sucrose dilaurate, the main impurity of the sucrose laurate product, however, resulted in large and polydisperse structures. Considering the critical packing parameters, the light scattering results could be explained by assuming a transformation of the spherical micelle into a disk with rounded edge.

Diffusion↗
PubMed2001

On reflectometric measurement of a refractive index of milk.

The refractive index of milk samples was measured with a reflectometer. Fresnel's formula for intensity reflectance and the concept of critical angle were applied to measured data. Milk samples were also measured with surface plasmon resonance sensor for refractive index assessment. The experiments were carried with commercial milk that had fat volume concentrations of 0.004, 1.53, and 3.55%. We observed that simultaneously quantitative information about the refractive index and absorption of milk, as a function of fat concentration, could be obtained with both devices.

Absorption↗
PubMed2007

The formation of calcium lactate crystals is responsible for concentrated acid whey thickening.

The use of spray drying for dehydration of acid whey is generally limited by the appearance of uncontrolled thickening and solidifying of the whey mass during the lactose crystallization step. The origin of this physical change is still unknown and probably linked to complex interactions between physical properties and chemical composition of these products. To understand this phenomenon, we simulated the thickening of concentrated acid whey on a laboratory scale by measuring the flow resistance changes as a function of time and whey composition. The thickening process was characterized by an amplitude of torque and a lag time (induction time). Thickening of lactic acid whey concentrate occurred regardless of the presence of whey proteins or lactose crystals. Moreover, this work clearly demonstrated that the thickening process was due to the formation of filamentous structures corresponding to calcium lactate crystals and showed a large dependence on calcium and lactate contents, pH, and phosphate concentration.

Calcium Compounds↗
PubMed1989

Effect of refeeding following short-term deprivation of feed or water, or both, on selected physiological parameters for broiler chickens.

Two experiments were conducted to determine the effects of refeeding broilers following a 12-h fast on body weight, serum glucose, serum protein, packed cell volume, hemoglobin, serum sodium, serum potassium, and plasma refractive index. Four fasting regimens were utilized in each experiment: 1) full feed and water (control); 2) no feed with full water; 3) full feed with no no water; and 4) no feed and no water (NFNW). Following the 12-h fast, all birds were returned to feed and water with ad libitum access. Birds deprived of feed or water, or both, for 12 h gained more weight attributable to feed and water consumption than did the control birds during the 12-h refeeding period. Following refeeding, serum glucose values for the birds receiving only water during the fast were higher initially than those for the control birds; glucose values for the NFNW birds returned to normal. Hemoglobin values for birds receiving no feed during the fast initially were higher than for the control group after refeeding. The other blood parameters measured remained virtually unchanged during the 12 h monitored after refeeding.

Animal Feed↗
PubMedDate not supplied

Refractive index of the human corneal epithelium and stroma.

BACKGROUND: The refractive index of the cornea must be determined to optically perfect keratorefractive procedures. There are very few empirical measurements of the human corneal refractive index described in the literature. Throughout its depth, the cornea demonstrates regional variations in physiological properties such as swelling/de-swelling characteristics. These properties suggest there may be a difference in the refractive index between the anterior and posterior corneal surfaces. METHODS: The refractive index of the human corneal epithelium of 10 eyes was measured, in vivo, using a modified hand-held refractometer. The refractive indices of the anterior and posterior surfaces of the bare stroma of fresh human corneas were measured using a bench model Abbe refractometer. RESULTS: The mean refractive index of the epithelium, stromal anterior and posterior surfaces were 1.401 (SD +/- 0.005), 1.380 (SD +/- 0.005), and 1.373 (SD +/- 0.001) respectively. CONCLUSIONS: The refractive index of the cornea is not uniform. The calculated dioptric power of the corneal epithelium is approximately -1.40 diopters (D). The varying refractive index does not significantly affect the total dioptric power of the cornea. The varying refractive index of the cornea has the potential to significantly contribute to the overall optical performance of the eye in relation to refractive surgery. The results should be incorporated into mathematical models, comparing and contrasting the optical performance of the eye before and after surgery.

Adult↗