Decreased estradiol receptor concentrations in ethionine-induced fatty liver of rats.

Ethionine, a methionine analogue, induces fatty liver in rats. The mechanism by which ethionine induces fatty liver is thought to be due to the inhibition of synthesis of very-low-density lipoprotein. Since the synthesis of lipoprotein is correlated with liver estradiol receptor concentrations, we examined the effect of ethionine on estradiol receptor concentrations in rat liver. Estradiol receptor concentrations in both cytosolic and nuclear fractions were greatly decreased by a single injection of ethionine at a dose of 0.5 mg/g body wt. In particular, the decrease in nuclear receptor concentrations was observed a few hours after the injection and correlated with the decrease in triglyceride content in the very-low-density lipoprotein fraction. These results suggest that liver estradiol receptor is involved in the pathogenesis of ethionine-induced fatty liver of rats.

Retinol transport system in cattle and purification of retinol-binding protein from bovine serum.

Retinol transport system in cattle was investigated, followed by the purification and characterization of bovine serum retinol-binding protein (RBP). Gel filtration of serum from cow produced two retinol peaks, peak 1 and 2. The major, peak 1 having higher molecular weight corresponded to the retinol peak from human serum which consisted of RBP and prealbumin (PA). The peak 2 which was not presented in the human serum had lower molecular weight (about 20,000). In the presence of 3.0 M urea, the peak 1 was almost disappeared and peak 2 was increased. On the other hand, in the serum from calf, major retinol peak was corresponded to the peak 2 from cow. These results suggested that, in cow, retinol was transported by the complex of RBP and another protein, presumably PA, but in calf, mainly by RBP alone. Purification of bovine RBP was carried out by using four chromatographic steps as follows; 1. DEAE-cellulose (pH 6.0), 2. Sephadex G-100 (using the buffer containing 3.0 M urea), 3. DEAE-cellulose (pH 8.3), 4. Sephadex G-100. From 1,100 ml of serum, 14.1 mg of bovine RBP was finally obtained and the overall recovery was estimated to be about 32%. Its molecular weight, ultraviolet absorption and fluorescence spectra, electrophoretic mobility, and amino acid composition were similar to those of other species.

Plasma prolidase activity as a possible diagnostic index of chronic hepatic abscess in cattle.

The usefulness of prolidase as a biochemical parameter to represent the chronic state of hepatic abscess was discussed in eight cattle experimentally inoculated with Fusobacterium necrophorum and 18 spontaneously affected cattle. Blood was daily collected to measure the plasma prolidase activity and sialic acid level from the experimental cattle for 90 days after inoculation. In three out of four cattle affected with hepatic abscess, prolidase activity began to rise about 40 days after inoculation, and maintained high activity till 90 days. In the same cattle the sialic acid concentration increased from 7 to 10 days after inoculation, and gradually returned to the normal value 50 days after it. Another cow showed a similar change in early stage of experiment, but prolidase activity decreased after 70 days and sialic acid concentration maintained high level till 90 days. In two cattle, which showed scars but no abscess on autopsy, the prolidase activity increased temporarily from 40 to 55 days after inoculation. In the control cattle inoculated with an inactivated bacterial suspension, neither the sialic acid level nor the prolidase activity showed any large variation in the experimental period. Among the spontaneously affected cattle, those with a high sialic acid level revealed normal prolidase activity and those with a normal sialic acid level had high prolidase activity.

The appearance of re-cycled urea in the digestive tract of goats during the final third of a once daily feeding of a low-protein ration.

1. An experiment was carried out with goats fed on a low-protein ration to clarify the importance of the rumen and significance of saliva in the appearance of re-cycled urea in the digestive tract during the final third of a once daily feeding regimen. The isotope-dilution method with [15N]urea and 15NH4Cl was used. 2. When the serum urea level was 58 mg N/l, the amount of urea transferred from the blood urea pool to the rumen ammonia pool was 48.6 mg N/h, which was estimated to be approximately 43% of the total amount of urea having appeared in the NH3 pool of the digestive tract. When the serum urea level was 106 mg N/l, the corresponding amount of NH3 was 77.7 mg N/h, which was estimated to be approximately 46% of this total amount. 3. The amount of saliva secreted was measured directly by the oesophageal fistula method. Salivary secretion serves as a mode of transfer of blood urea to the rumen NH3 pool. Then the ratio, salivary secretion:diffusion through the rumen wall during the final third of the cycle was calculated to be 1:4-1:6. 4. In goats fed on a low-protein diet, the rumen is an important site of appearance of blood urea in the digestive tract. It was verified that the principal mode of transfer of blood urea to the rumen was the direct diffusion through the wall of the rumen.

Intraruminal injection of urea and changes in secretion of parotid saliva in sheep.

1. Sheep were injected with varying doses of urea into the rumen and changes in the amount of saliva secreted from one parotid gland were studied. When the dose of urea was 0.1-0.2 g/kg, the secretion underwent no change. When the dose was 0.3 g/kg, the secretion was inhibited. When the dose was 0.4 or 0.5 g/kg, there was a marked inhibition in the secretion. 2. There was a close relationship between the ammonia level of the jugular blood and the inhibition of salivary secretion. When the ammonia level exceeded approximately 0.28 mmol/l, the secretion was inhibited abruptly. 3. Salivary secretion and rumen movement were inhibited when the blood ammonia level exceeded 0.28 mmol/l, after injection of ammonium acetate into the jugular vein. 4. Based on the results mentioned previously, the mechanism of inhibition on the secretion of parotid saliva is discussed in relation to the domestic ruminant in which urea had been injected into the rumen.