A high level of transferrin mRNA in the liver of analbuminemic rats

Novel role for albumin in innate immunity: serum albumin inhibits the growth of Blastomyces dermatitidis yeast form in vitro

In this study we found that serum inhibitory activity against Blastomyces dermatitidis was principally mediated by albumin. This was confirmed in experiments using albumin from several mammalian species. Analbuminemic rat serum did not inhibit B. dermatitidis growth in vivo; however, the addition of albumin restored inhibitory activity. Inhibitory activity does not require albumin domain III and appears to involve binding of a low-molecular-weight yeast-derived growth factor.

Iron and copper metabolism in analbuminaemic rats fed a high-iron diet

The metabolism of iron and copper in male Nagase analbuminaemic (NA) and Sprague Dawley (SD) rats was compared. Relative liver weight was higher and spleen weight significantly lower in NA than SD rats. In NA rats, red blood cell count, haemoglobin and haematocrit were lower, whereas plasma transferrin, total iron-binding capacity and mean corpuscular haemoglobin were higher when compared with SD rats. Iron concentrations in plasma, liver, kidneys and heart were higher, and those in the spleen and tibia were lower, in NA rats. The iron concentrations in liver and spleen were positively correlated with the amount of brown pigment as observed histopathologically. Bile flow as well as biliary iron and copper excretion were higher in NA than SD rats. Copper concentrations in liver, kidneys and plasma were higher in NA rats. Plasma levels of ceruloplasmin were about two-fold higher in NA rats. The feeding of a high-iron diet reduced kidney copper concentrations in both strains of rats, which was associated with a decrease in the absorption and biliary excretion of copper.

Tumor-associated expression of a serum protein, termed aX protein (alpha 1-inhibitor III), and its mRNA in rat liver

A cDNA clone bearing the mRNA sequence for rat alpha X protein (alpha X) was isolated from a cDNA library constructed from rat liver mRNA. The nucleotide sequence of alpha X protein cDNA showed 97% homology with that of the 3'-proximal domain of alpha 1-inhibitor III cDNA. The amino acid sequence deduced from that of alpha X cDNA also exhibited high homology with the primary sequences of alpha 1-inhibitor III and alpha 2-macroglobulin. K231 ascites hepatoma cells were transplanted into male ACI rats, and the level of alpha X mRNA in the liver of the tumor-bearing rats was determined by RNA blot hybridization with the cDNA probe. The serum concentration of alpha X decreased to about 30% of the control value with time after transplantation. The amount of alpha X mRNA in the liver of tumor-bearing rats was proportional to the serum concentration of alpha X. The serum concentrations of transferrin and albumin in the tumor-bearing rats also decreased to about 30 and 60% of the normal levels, respectively. However, the amounts of mRNAs for transferrin and albumin in the liver of tumor-bearing rats did not decrease. These findings indicate that the mechanisms of tumor-associated decrease in the concentrations of different serum proteins in tumor-bearing rats may differ.

Plasma proteins in growing analbuminaemic rats fed on a diet of low-protein content

1. Analbuminaemic and Sprague-Dawley (control) rats were fed on low- (60 g/kg) protein and control (200 g protein/kg) diets ad lib. from weaning. Males and females were studied separately. Body-weight and plasma protein concentrations were determined at 10 d intervals from 25 to 75 d of age. Electrophoresis of plasma proteins was performed in samples from day 75. Extracellular fluid volume was measured at 10 d intervals from day 45 onwards. Colloid osmotic pressure was measured in plasma and interstitial fluid (wick technique) at the start and end of the trial. 2. Body-weight increased much less on the low-protein diet than on the normal diet in both strains and sexes. The growth retardation was slightly more pronounced in the male analbuminaemic rats than in the male Sprague-Dawley controls. 3. Plasma protein concentration increased during normal growth in all groups, particularly in the female analbuminaemic rats. This increase was reduced by the 60 g protein/kg diet in all groups, with the exception of the male analbuminaemic rats. 4. Differences in plasma colloid osmotic pressure were similar to those seen in plasma protein concentration. Interstitial colloid osmotic pressure was higher in the control rats than in the analbuminaemic ones. The interstitial colloid osmotic pressure increased during growth in the control but not in the analbuminaemic rats. The difference in interstitial colloid osmotic pressure between the strains was maintained during low-protein intake, but at a lower level than during normal protein intake. 5. Subtracting interstitial from plasma colloid osmotic pressure, resulted in a rather similar transcapillary oncotic gradient in the various groups at 75 d, both on the control protein diet (11-14 mmHg), and on the low-protein diet (9-11 mmHg). 6. All protein fractions were reduced to a similar extent by the low-protein diet in the control rats, whereas in the analbuminaemic rats protein fractions produced in the liver were more severely depressed. 7. Extracellular fluid volume as a percentage of body-weight was similar in all groups, and decreased with increasing age. 8. In conclusion, the analbuminaemic rats were able to maintain the transcapillary oncotic gradient on both diets by reducing the interstitial colloid osmotic pressure. Oedema was not observed. 9. Despite the absence of albumin, the protein-malnourished analbuminaemic rat is no more susceptible to hypoproteinaemia and oedema than its normal counterpart.