Assessment of in vivo mast cell reactivity in patients with systemic mastocytosis.

BACKGROUND: Patients with systemic mastocytosis (SM) have clinical signs of mast cell (MC) activation and increased levels of MC mediators. It is unclear whether the increased mediator levels are caused by increased numbers of tissue MCs, or whether these cells in affected individuals have a hyperactive phenotype. OBJECTIVE: To determine reactivity of the skin and the airways to directly acting mediators and indirectly acting mast cell secretagogues in subjects with SM. METHODS: Skin reactivity to morphine and histamine, and airway responsiveness to mannitol and methacholine, was assessed in 15 patients with SM, 11 patients with allergic asthma (A) and 13 healthy controls (HC). Serum tryptase and urinary metabolites of the MC mediators histamine and prostaglandin D2 were measured, as well as ex vivo basophil histamine release. RESULTS: Mast cell mediators in the blood and urine were significantly higher in patients with SM than in HC and A controls. Responsiveness to local activation of skin MCs (by morphine) and airway MCs (by mannitol) was similar in SM and HC groups. Likewise, end-organ responsiveness in the skin to histamine, and in the airways to methacholine, was similar in all three subject groups. There was no evidence of increased basophil reactivity in SM patients. CONCLUSIONS AND CLINICAL RELEVANCE: Mast cells in the skin and airways of subjects with SM do not exhibit hyper-reactivity towards the MC-activating stimuli morphine and mannitol, respectively. Therefore, the highly elevated baseline levels of MC mediators in SM are most likely due to increased MC numbers, rather than altered MC responsiveness. The underlying mechanisms could involve leakage of MC mediators, or dysfunctions in mediator synthesis, storage and release. One clinical implication of our study is that there is no contraindication to perform skin tests using morphine in subjects with mastocytosis.

Ileal and total tract digestibility of wet and dried wheat distillers grain products in growing pigs.

The apparent ileal digestibility (AID) and apparent total tract digestibility (ATTD) of nutrients were evaluated in 2 commercially available products: wheat (Triticum aestivum) wet distillers grain with solubles (WDGS) and wheat dried distillers grain with solubles (DDGS). Two diets included (DM basis) 50% basal diet with either 50% WDGS (W) or 50% DDGS (D). The basal diet included corn (Zea mays) starch, sugar, vitamins, and minerals. Seven castrated male pigs with post valve T-cecum cannulas were fed the diets according to a changeover design during two 14-d periods. In a pre- and postperiod, casein was given as the only protein source with the basal diet to estimate endogenous losses of N and AA for calculation of standardized ileal digestibility (SID). The AID of OM did not differ between diets, but ATTD of OM was higher (P < 0.05) for diet W. The AID (76.2 vs. 68.9%), SID, and ATTD of CP was higher (P < 0.05) in diet W than diet D. The SID for Lys (75.7 vs. 51.8%) and Met (75.8 vs. 70.1%) was higher (P < 0.01) in WDGS than DDGS. In conclusion, drying of wheat distillers grain products can markedly lower ileal digestibility of Lys and Met whereas negative effects on energy value are small.

Influence of different phosphorus levels and phytase supplementation in gestation diets on sow performance.

A total of 104 sows of different parities were studied. They were fed four diets with different phosphorus (P) levels during gestation for two reproductive cycles, while the same diet was fed during lactation. The aim was to decrease the total P level in the diet during gestation and to evaluate the effect on sow performance. The gestation treatments were low P (LP-; 3.7 g P/kg feed), low P with phytase (LP+, Ronozyme P; 765 FTU/kg feed), medium P (MP; 4.5 g P/kg feed) and high P (HP; 6.0 g P/kg feed). Daily feed allowances were 2.6 kg during gestation and 9.2 kg during lactation. Number of born piglets and piglet mortality were higher (p < 0.05) in the LP treatments than in the MP and HP treatments. No difference (p > 0.05) in the numbers of live-born piglets, piglet birthweights, sow weights or piglet weight gains was found between the treatments. Phosphorus level in sow milk was the highest (p < 0.05) in the MP treatment, while no effects (p > 0.05) of treatment were found on milk Ca levels, P and Ca levels in serum of sows and piglets, nor on the analysed mineral, fat and protein contents of piglets. The estimated average requirement of P for the entire gestation period was 4.4-4.5 g/day. In conclusion, a reduction of dietary total P content during gestation did not result in negative effects on sow or piglet performance. This suggests that it should be possible to lower the dietary P content for gestating sows, compared with earlier recommendations, and thereby reduce the environmental P pollution.