Mechanism of uptake of sulfonated metallophthalocyanines by cultured mammalian cells.

The uptake of several metallophthalocyanine tetrasulfonates by cultured Chinese hamster cells was studied. Uranyl- and chloraluminium were taken up at the highest rate followed by Ni-, Zn-, Cu-, Co- and dichlorosilicon-phthalocyanine tetrasulfonate. The uptake from the growth medium containing 10% serum in which only 15% of the dye is not bound to serum proteins was 5--18-fold slower than in the absence of serum, suggesting that most of the uptake is of free dye. Using gel filtration to separate tightly protein-bound dye from the free dye, binding curves were constructed that varied in slope and saturation values for the different compounds. At saturation, the number of dye molecules bound per serum albumin molecule varied from 1 for vanadyl- and cobalt-, to 4 for uranyl-phthalocyanine tetrsulfonate. Absorption spectra of the various phthalocyanines indicated that under physiological conditions, all dyes, with the exception of chloroaluminum- and dichlorosilicon-phthalocyanine tetrasulfonate, were aggregated. The rate of uptake was unrelated to the state of aggregation. The rate of uptake was temperature dependent at intervals longer than 1 h. At shorter times, very little temperature dependence was observed. These results suggest that the uptake process takes place in two steps. The first step is passive, involving binding of metallophthalocyanine tetrasulfonate to a receptor on the cell membrane, while the second one is active and involves internalization of the bound dye.

Dietary ascorbic acid for neonatal pigs reared artificially.

During the first 21 d of feeding a casein-glucose liquid diet the performance of pigs weaned at 1-3 d of age was not affected by ascorbic acid (AA) added at levels ranging from 165 to 990 ppm in two experiments. However, AA tended to improve growth rate from d 22 to 36 in experiments where pigs were fed a dry diet, but not when fed the diet in liquid form. The concentrations of AA in plasma, spleen and small intestinal tissues increased linearly with increasing dietary AA. No evidence of variability of AA concentration in adrenals was observed, whereas its content in the liver was increased only at 990 ppm AA. The AA concentrations in the small intestinal tissue increased progressively from the duodenum, jejunum to the ileum, mainly due to the increase in AA in the mucosal compared with the serosal layer. Dietary AA had no effect on the blood hematocrit, hemoglobin or on the concentrations of glucose or urea-N in plasma and protein in organs and intestinal tissues.

The biotin status of weanling pigs fed semipurified diets as evaluated by plasma and hepatic parameters.

Twenty-four pigs were weaned at four weeks of age and fed either spray dried egg albumen (DA) or autoclaved DA (ADA) as the only protein source were used to evaluate plasma and hepatic parameters as indicators of biotin status. Pigs were fed one of four semipurified diets during the 42-day study: DA basal, DA + 1.1 g sulfamethazine/day (DA + S), ADA basal or ADA + .5 mg biotin/day (ADA + H). Autoclaving DA at 121 degrees C for 30 minutes reduced both the biotin binding properties of the avidin fraction and the trypsin inhibitor activity of DA. Pigs fed ADA and ADA + H had greater (P less than .05) liver pyruvate carboxylase (EC 6.4.1.1) activity and DNA concentrations, lower (P less than .05) plasma urea nitrogen levels and greater and more efficient (P less than .05) weight gain than either DA or DA + S fed pigs. Biotin supplementation further enhanced (P less than .05) liver DNA concentration but had no effect on the liver levels of RNA or total protein. Plasma levels of glucose and free fatty acids or blood levels of lactate and pyruvate were not influenced by the addition of biotin to the ADA basal diet.