Preliminary assessment of potential health hazards associated with barium leached from glazed ceramicware.

Ceramic glazes contain several elements which have the potential to leach into food or beverages that are held or stored in ceramicware. Recently, barium salts have been investigated as one of the alternatives to lead in frit formulations for glazes. This preliminary evaluation addresses the potential health hazards associated with barium at levels that might leach from glazed ceramicware. A set of specialty ceramicware, consisting of five teacups and a pitcher, was examined for extractable barium. Exposure to barium that adults (18-44 years) might encounter using the vessels for coffee, tea, or orange juice was estimated. The exposure estimate was derived from values for intakes of the beverages and for the barium migration from glazed ceramicware test samples. An established reference dose (RfD) for barium exposure for the critical effect of hypertension was identified. The potential hazard associated with the leaching of barium from glazed ceramicware varied with the level of use. Consuming beverages in amounts up to the 95th percentile would not result in total barium intake in amounts that exceed the RfD; consuming large quantities (> 95th percentile) of beverages such as tea or coffee from glazed vessels might. This suggests that for a small portion of the population of users, intake of barium may be in quantities that warrant further consideration as a potential health hazard. Analyses of a broad sample of ceramicware and study of barium leaching behaviour under actual use conditions are needed to assess further the significance of these findings.

Digestible fiber (gum arabic), nitrogen excretion and urea recycling in rats.

The effect of dietary fiber and level of amino acid (AA) intake on 1) partitioning of N excretion between urine and feces, 2) level of dietary AA on urea N kinetics, and 3) reutilization of urea-originated N into essential AAs was determined. In the first experiment, rats were adapted to one of two isocaloric (928-mJ.kg-1.day-1) and isonitrogenous (1.33-g N.kg-1.day-1) liquid diets containing 0 or 9% of nonprotein energy as gum arabic (GA) for 7 days. The rats were further subdivided, with half from each group continuing their diet and the AA intake of the remainder reduced by half (0.67 g N.kg-1.day-1). Daily N balance was determined over the next 5 days. For experiment 2, a catheter was inserted into the rats used for experiment 1, and 5-6 days later, urea production and urea N recycling were determined with [15N2]urea. In experiment 3, as in experiment 1, rats were adapted to the reduced AA diet with and without GA and then given [15N2]urea. Plasma lysine was then analyzed for 15N to determine whether AA synthesis by intestinal bacteria was a contributing source of AAs to the body and whether this process was increased with dietary fiber. Dietary fiber decreased urinary N excretion and increased fecal N excretion but had no net effect on N balance. On the adequate-AA diet, GA decreased urea production (523 +/- 36 vs. 374 +/- 47 mg N.rat-1.day-1, p < 0.01), and urea N recycling (47 +/- 4 vs. 30 +/- 6 mg N.rat-1.day-1, p < 0.01) was found.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison of intravenous nutrients on gut mucosal proteins synthesis.

BACKGROUND: Total parenteral nutrition (TPN) is associated with atrophy of the intestinal mucosa. This study compared the relative effectiveness of a short-chain fatty acid (butyrate), a physical mixture of medium-chain and long-chain triglycerides, structured lipid, and glutamine as components of a TPN regimen, and their ability to support mucosal protein synthesis. METHODS: Rats were parenterally fed one of six isocaloric (1003 kJ/kg.d-1) and isonitrogenous (1.5 g.kg-1.d-1 of nitrogen) diets for 5 days. Diet 1, glucose 90% and long-chain triglycerides 10% (standard TPN); diet 2, glucose 50% and long-chain triglycerides 50%; diet 3, glucose 50% and a 50/50 physical mixture of long-chain and medium-chain triglycerides 50%; diet 4, glucose 50% and structured lipid 50%; diet 5, glucose 91% and sodium butyrate 9%; and diet 6, same as group 1 except that some of the amino acids were replaced with glycyl glutamine. A control group of rats also underwent catheter placement and were instead fed diet 1 orally for 5 days. Five days after catheterization, all rats were given a 4-hour constant infusion of [U-14C]leucine to determine the mucosal fractional protein synthesis rates. RESULTS: (1) Mucosal fractional protein synthesis rates were much higher with the oral diet (control) than with any of the intravenous diets. (2) Diet-related differences in the mucosal fractional synthesis rates were found with the jejunum and the proximal and distal colon but not with the ileum. (3) Standard TPN was the least effective diet in supporting mucosal protein synthesis. (4) Structured lipid and butyrate were most effective for the jejunum. (5) For the colon, medium-chain triglycerides and structured lipid were most effective. CONCLUSION: Standard TPN leads to a decrease in gut mucosal protein synthesis in rats, and this decrease can be partially attenuated by adding nutrients for the gut to the TPN mixture.

Maternal and nutritional contributions to infant rats' activational responses to ingestion.

Infant rats deprived of food, maternal care, and the opportunity to suckle display a dramatic behavioral activation and vigorously ingest when provided milk through oral cannulas. These experiments assessed which components of deprivation are important in producing these responses to milk. Nutritional deprivation alone, with or without the presence of an active maternal female, appears to be sufficient to produce ingestion. Behavioral activation, on the other hand, appears to require both nutritional deprivation and deprivation from a maternal female. The effect of maternal stimulation on later behavioral reactivity was not a function of the pups' opportunity to suckle. However, active maternal stimulation was more effective in preventing activation than was passive maternal stimulation (e.g., thermotactile and olfactory stimulation). Stimulation provided by an active, nonlactating mother was effective in preventing behavioral activation, but the effect was short-lived, lasting only 2 hr after the pup was removed from the mother's care. This series of studies thus reveals that identified components of maternal separation have dissociable effects on appetitively motivated behaviors in infant rats.

The effect of diet on food intake and adiposity in rats made obese by gestational undernutrition.

Undernutrition limited to the first two weeks (trimesters) of pregnancy in rats produces a delayed-onset enhancement of body weight and food intake in male but not female offspring. Adiposity measures (fat cell size, fat pad weight and carcass lipid content) however, were enhanced only in male offspring of previously deprived mothers maintained on a high-fat diet. Previous work had shown that although these adiposity differences are enhanced by this diet, hyperphagia was eliminated when animals were switched to the high-fat diet as adults. The current study demonstrates that if offspring of deprived animals are exposed to the high-fat diet early in life, hyperphagia ensues. Adipocyte number, and circulating triglyceride levels were unaffected by our nutritional manipulation.

Adipose tissue mobilization is unaffected by obesifying hypothalamic knife cuts.

Unilateral electrolytic lesions of the medial hypothalamus have previously been reported to spare starvation-induced lipid mobilization from the ipsilateral retroperitoneal fat pad. This suggests that deficient lipid mobilization contributes to the enhanced lipid deposition which results when such lesions are bilateral. In contrast, unilateral parasagittal hypothalamic knife cuts, which also obesify when bilateral, failed to prevent starvation-induced ipsilateral lipid mobilization. This finding indicates that impairment of neurally mediated lipid mobilization is probably neither a necessary nor a sufficient feature of hypothalamic obesity.