scholarly journals Nitrogen balance in adult female mink (Mustela vison) in response to normal feeding andshort-term fasting

1997 ◽  
Vol 78 (1) ◽  
pp. 83-96 ◽  
Author(s):  
Anne-Helene Tauson ◽  
Jan Elnif ◽  
Søren Wamberg
Keyword(s):  
Urinary Excretion ◽  
Renal Clearance ◽  
Adult Female ◽  
Accurate Determination ◽  
Mustela Vison ◽  
Published Data ◽  
Purine Derivatives ◽  
Total N ◽  
Creatinine Excretion

Ten adult female mink (Mustela vison) were studied in a 7 d balance experiment consisting of a 2 d pre-surgery feeding period, followed by surgery, 1 d of recovery, 4 d of ad libitum feeding, and a 2d fasting period. In this experiment (Expt A) the animals had osmoticpumps implanted for continuous release of radioactively-labelled p–aminohippuric acid (p–aminobenzoyl-2-[3H]glycine; [3H]PAH;n10) and 14C-labelled inulin ([14C]IN; n 5). Repeated 24 h collections of urine, corrected to 100%[3H]PAH or [14C]IN recovery, were used for accurate determination of N balances, 24 h urinary excretion of urea, creatinine, and total N, and calculation of mean 24 h renal clearance rates for endogenous creatinine and inulin. N balances were slightly below zero, but not significantly different between feeding and fasting periods, indicating that correction to 100% [3H]PAH recovery resulted in slight overestimation of thefinal balances. During fasting, withdrawal of the dietary water and protein loads resulted in a dramatic decline in 24 h urinary volume, and urea and creatinine excretion. Large individualvariations in 24h urinary creatinine excretion (with relative variation coefficients up to 30%) confirmed that this is an unreliable index of the completeness of urine collection. In this respect, recovery rates of [3H]PAH proved far more consistent. Renal clearance values obtained in fed mink were in fair agreement with published data from cats, dogs and ferrets (Mustela putorius furo). Inulin clearance was about 30% higher than endogenous creatinine clearance, although its decline in response to fasting was not significant. In a separate study (Expt B)another ten female mink were equipped with osmotic pumps containing [3H]PAH for determination of 24 h excretion rates of purine derivatives. During feeding, allantoin accounted for more than 97 % of the excretion of purine derivatives in urine, uric acid making up less than 2·5%, xanthine and hypoxanthine less than 1 %. In fasted animals, urinary excretion of each of these purine derivatives declined to less than 50% of the feeding value. In conclusion, an experimental technique is presented for efficient and accurate measurements of daily urinary excretion of nitrogenous constituents, which allows for correct determination of N balances in adult mink and, presumably, in other mammalian species.

Prediction of the excretion of allantoin and total purine derivatives by sheep from the ‘creatinine coefficient’

1995 ◽  
Vol 125 (3) ◽  
pp. 425-428 ◽  
Author(s):  
G. J. Faichney ◽  
R. J. Welch ◽  
G. H. Brown
Keyword(s):  
Purine Derivatives ◽  
Purine Derivative ◽  
Creatinine Excretion ◽  
Total Urine

SUMMARYThe urinary excretions of creatinine, allantoin and total purine derivatives by Merino ewes were compared with predictions based on the assumptions that creatinine excretion scaled to liveweight (the creatinine coefficient) was constant and was not affected by diet. The creatinine coefficient varied between individuals and was found to be affected by diet (P<0·01). As a result, there were systematic deviations (p<0·01) in the predictions of allantoin and total purine derivative excretion. If predictions of purine derivative excretion are to be made for individual animals in the absence of total urine collections, prior determination of individual creatinine coefficients is required and predictions may be confounded by diet effects on creatinine excretion. Predictions for groups on the basis of general relationships between the creatinine coefficient and liveweight may be subject to errors between diets of > 10%.

On the variation of urinary excretion of creatinine and purine derivatives in pregnant and lactating ewes given diets with different protein contents

1999 ◽  
Vol 68 (3) ◽  
pp. 555-566 ◽  
Author(s):  
C. Dapoza ◽  
C. Castrillo ◽  
J. Balcells ◽  
S. Martín-Orúe ◽  
J. A. Guada
Keyword(s):  
Organic Matter ◽  
Plasma Concentration ◽  
Urinary Excretion ◽  
Dietary Protein ◽  
Protein Level ◽  
Fish Meal ◽  
Physiological State ◽  
Purine Derivatives ◽  
Creatinine Excretion ◽  
Dietary Protein Level

AbstractThe effect of the physiological state and dietary protein level on urinary excretion of creatinine (C) and purine derivatives (PD) was studied in two experiments carried out with pregnant and lactating ewes to evaluate whether the PD/C ratio in urine can he confidently used as an index of PD excretion. In both experiments ewes were given ammonia-treated straw and concentrates including different levels of fish meal and the excretion in urine and milk and the plasma concentration of C, allantoin (AL), xanthine, hypoxanthine and uric acid was measured.Creatinine excretion (in urine and milk) was higher in pregnant ewes than in those lactating (492 and 420 (s.e. 10.0) μmol/kg maternal live weight0.75) and no significant differences were found due to number of foetuses and dietary protein level. The coefficient of variation was 0·10 in both pregnancy and lactation and individual variation accounted for proportionately 0·78 and 0·93 of total variation. The AL/C ratio in urine was highly correlated with daily AL excretion (r = 0·90 and 0·78 in pregnant and lactating ewes, respectively). Changes in PD excretion with experimental treatments were mainly reflected in AL, as the main component (0-83) of total PD. Most of the variation in AL excretion was explained by differences in rumen fermentable organic matter intake (RFOMI) (R2 = 0·79) and AL excretion did not differ between treatments when expressed per kg of RFOMI. In contrast to this the ratio AL/digestible organic matter intake decreased with increasing levels of fish meal in the diet. Urinary PD excretion was better related to estimated PD kidney tubular load (r = 0·76) than to PD plasma concentration (r = 0·64).The results suggest that creatinine excretion is scarcely affected by the number of foetuses in pregnancy and dietary protein level but if the AL/С in urine is used instead of total collection as an index of purines absorbed in the duodenum, differences in urinary creatinine excretion due to physiological state must be accounted for.

scholarly journals Urinary excretion of purine derivatives and tissue xanthine oxidase (EC 1.2.3.2) activity in buffaloes (Bubalis bubalis) with special reference to differences between buffaloes and Bos taurus cattle

1996 ◽  
Vol 75 (3) ◽  
pp. 397-407 ◽  
Author(s):  
X. B. Chen ◽  
L. Samaraweera ◽  
D. J. Kyle ◽  
E. R. Ørskov ◽  
H. Abeygunawardene
Keyword(s):  
Uric Acid ◽  
Urinary Excretion ◽  
Xanthine Oxidase ◽  
Intestinal Mucosa ◽  
Bos Taurus ◽  
Purine Derivatives ◽  
Fresh Tissue ◽  
Creatinine Excretion ◽  
Digestible Organic Matter ◽  
Cattle And Sheep

AbstractThe urinary excretion of purine derivatives (PD) was measured in six buffaloes (Bubalis bubalis) during fasting and in fourteen buffaloes given four restricted levels of roughage (2·5-4·8 kg DM/d). Only allantoin and uric acid, not xanthine and hypoxanthine, were present in the urine, the pattern of excretion being similar to that in cattle. The fasting PD excretion amounted to 0·20 (SD 0·06) mmol/kg metabolic weight (W0·75) per d, and the rate of PD excretion as a linear function of feed intake was 5·2 mmol/kg digestible organic matter intake. Both values were considerably lower than the values for cattle reported in the literature. Creatinine excretion values were 0·33 (SD 0·06) and 0·44 (SD 0·09) mmol/kg W0.75 per d determined in fasting and feeding periods respectively. Fasting N excretion was 257 (SD 49) mg N/kg W0.75 per d. Both creatinine and fasting N excretions were also lower than in cattle. The activities of xanthine oxidase (EC 1.2.3.2) in plasma, liver and intestinal mucosa were determined in buffaloes, cattle and sheep. Xanthine oxidase activities in buffaloes were 24·5 (SD 2·7) unit/l plasma and 0·44 (SD 0·02) and 0·31 (SD 0·10) unit/g fresh tissue in liver and intestinal mucosa respectively. These activities were higher than those in cattle and sheep. Xanthine oxidase was practically absent from plasma and intestine of sheep. It is suggested that the differences in PD excretion between buffaloes and cattle were probably due to the smaller proportion of plasma PD that was disposed of in the urine of buffaloes.

scholarly journals The determination of the minimal nitrogen excretion in steers and dairy cows and its physiological and practical implications

1982 ◽  
Vol 47 (3) ◽  
pp. 625-636 ◽  
Author(s):  
E. R. Ørskov ◽  
N. A. MacLeod
Keyword(s):  
Urinary Excretion ◽  
Dairy Cows ◽  
Live Weight ◽  
Nitrogen Excretion ◽  
Total N ◽  
Mean Values ◽  
Practical Implications

1. Cattle were maintained by intragastric infusion to see how much nitrogen was excreted on protein-free diets.2. Minimal N excretion was estimated with two dairy cows in three periods, i.e. when they were non-pregnant and non-laclating, when they were between 117 and 133 d pregnant and when they were between 220 and 233 d pregnant. The minimal N excretion was also estimated on two occasions with two steers when their average live weights were 200 and 350 kg.3. Average urinary N excretion without protein infusion was 298, 305 and 283 mg/kg metabolic live weight (W0·75) for the non-pregnant cows and for cows during the first and second periods of pregnancy respectively; total N excretion including the faecal N was 340, 329 and 319 g/kg W0·75.4. For steers the urinary N values were 403 and 295 mg/kg W0·75at 200 and 350 kg live weight respectively and total N excretion including faecal N was 408 and 320 mg/kg W0·75.5. Urinary excretion of creatinine was the same for animals given casein via the abomasum as a source of protein or given no protein with mean values for the cows of 13·6 and 14·9 g/d for the first and second stages of pregnancy respectively. Mean values for the steers were 6·5 and 7·6 g creatinine/d at 200 and 350 kg live weight respectively.6. It is suggested that the so-called metabolic faecal N in ruminants, estimated with N-free diets, is mainly endogenous N derived from tissue breakdown of protein but incorporated in microbial debris and excreted in the faeces.

A quantitative approach to inner shell losses

1978 ◽  
Vol 36 (1) ◽  
pp. 526-527 ◽  
Author(s):  
R.D. Leapman ◽  
P. Rez ◽  
D.F. Mayers
Keyword(s):  
Energy Transfer ◽  
Cross Section ◽  
Cross Sections ◽  
Accurate Determination ◽  
Background Intensity ◽  
Core Excitation ◽  
Quantitative Basis ◽  
Cross Section Differential ◽  
Bound Electrons

Microanalysis by EELS has been developing rapidly and though the general form of the spectrum is now understood there is a need to put the technique on a more quantitative basis (1,2). Certain aspects important for microanalysis include: (i) accurate determination of the partial cross sections, σx(α,ΔE) for core excitation when scattering lies inside collection angle a and energy range ΔE above the edge, (ii) behavior of the background intensity due to excitation of less strongly bound electrons, necessary for extrapolation beneath the signal of interest, (iii) departures from the simple hydrogenic K-edge seen in L and M losses, effecting σx and complicating microanalysis. Such problems might be approached empirically but here we describe how computation can elucidate the spectrum shape.The inelastic cross section differential with respect to energy transfer E and momentum transfer q for electrons of energy E0 and velocity v can be written as

Fast calibration of CBED patterns for quantitative analysis

1993 ◽  
Vol 51 ◽  
pp. 674-675
Author(s):  
M.A. Gribelyuk ◽  
M. Rühle
Keyword(s):  
Reciprocal Lattice ◽  
Accurate Determination ◽  
Incident Beam ◽  
Crystal Thickness ◽  
Structure Model ◽  
Beam Direction ◽  
Transmitted Beam ◽  
Reciprocal Vector ◽  
On Line

A new method is suggested for the accurate determination of the incident beam direction K, crystal thickness t and the coordinates of the basic reciprocal lattice vectors V1 and V2 (Fig. 1) of the ZOLZ plans in pixels of the digitized 2-D CBED pattern. For a given structure model and some estimated values Vest and Kest of some point O in the CBED pattern a set of line scans AkBk is chosen so that all the scans are located within CBED disks.The points on line scans AkBk are conjugate to those on A0B0 since they are shifted by the reciprocal vector gk with respect to each other. As many conjugate scans are considered as CBED disks fall into the energy filtered region of the experimental pattern. Electron intensities of the transmitted beam I0 and diffracted beams Igk for all points on conjugate scans are found as a function of crystal thickness t on the basis of the full dynamical calculation.

Computer-Assisted High-Re Solution TEM

1990 ◽  
Vol 48 (1) ◽  
pp. 162-163
Author(s):  
F.A. Ponce ◽  
H. Hikashi
Keyword(s):  
Signal To Noise Ratio ◽  
Accurate Determination ◽  
Computer Software ◽  
Video Camera ◽  
Image Contrast ◽  
Objective Lens ◽  
Computer Assisted ◽  
Optical Parameters ◽  
Astigmatism Correction

The determination of the atomic positions from HRTEM micrographs is only possible if the optical parameters are known to a certain accuracy, and reliable through-focus series are available to match the experimental images with calculated images of possible atomic models. The main limitation in interpreting images at the atomic level is the knowledge of the optical parameters such as beam alignment, astigmatism correction and defocus value. Under ordinary conditions, the uncertainty in these values is sufficiently large to prevent the accurate determination of the atomic positions. Therefore, in order to achieve the resolution power of the microscope (under 0.2nm) it is necessary to take extraordinary measures. The use of on line computers has been proposed [e.g.: 2-5] and used with certain amount of success.We have built a system that can perform operations in the range of one frame stored and analyzed per second. A schematic diagram of the system is shown in figure 1. A JEOL 4000EX microscope equipped with an external computer interface is directly linked to a SUN-3 computer. All electrical parameters in the microscope can be changed via this interface by the use of a set of commands. The image is received from a video camera. A commercial image processor improves the signal-to-noise ratio by recursively averaging with a time constant, usually set at 0.25 sec. The computer software is based on a multi-window system and is entirely mouse-driven. All operations can be performed by clicking the mouse on the appropiate windows and buttons. This capability leads to extreme friendliness, ease of operation, and high operator speeds. Image analysis can be done in various ways. Here, we have measured the image contrast and used it to optimize certain parameters. The system is designed to have instant access to: (a) x- and y- alignment coils, (b) x- and y- astigmatism correction coils, and (c) objective lens current. The algorithm is shown in figure 2. Figure 3 shows an example taken from a thin CdTe crystal. The image contrast is displayed for changing objective lens current (defocus value). The display is calibrated in angstroms. Images are stored on the disk and are accessible by clicking the data points in the graph. Some of the frame-store images are displayed in Fig. 4.

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