Adenoviral-mediated gene transfer into bone marrow: an effective surgical technique in rat.

BACKGROUND: The role of transforming growth factor-beta 1 (TGF-ß1) in the onset of bone marrow fibrosis has been confirmed in some animal models. To further understand the genetic expression of some myeloproliferative disorders affecting marrow stem cells, however, it is necessary to develop a specific and reliable procedure to deliver modified adenoviral vectors into the bone marrow cavity. The aim of this paper is to report a surgical technique designed to deliver an adenoviral vector-mediated gene expressing TGF-ß1 into the bone marrow of rat femurs. METHODS: Forty-two Sprague-Dawley rats were used in the study. Rat femurs were exposed and the compact and trabecular bones at the proximal head removed. An intrabone marrow injection of a mutated TGF-ß1 adenoviral vector, a null adenoviral vector, or PBS was delivered into the bone. Three groups were accounted (n = 14 per group): fibrogenic and positive and negative controls. The quality of the surgical entrance was assessed by means of computerized tomography and histological changes were assessed by histochemistry. The concentration of TGF-ß1 in the bone marrow was determined by ELISA. RESULTS: The surgical technique was conducted under ideal timing (approx. 10 min) and no surgical or postsurgical complications were observed. Computerized tomography revealed no changes in the bone tissue and a clean entrance was delimited through the bone to the bone marrow. HE and Masson's trichrome staining indicated highly fibrotic areas in the profibrotic group and bone marrow lavage reported a significantly higher concentration of TGF-ß1 (p < 0.05) in that same group. CONCLUSIONS: The present study confirmed that the proposed surgical technique is an effective method to deliver adenoviral vectors into the femoral bone marrow to investigate the physiopathology of bone marrow fibrosis in rats.

Supplementation of increasing amounts of linseed oil to dairy cows fed total mixed rations: effects on digestion, ruminal fermentation characteristics, protozoal populations, and milk fatty acid composition.

The effect of linseed oil (LO) supplementation on nutrient digestibility, forage (i.e., timothy hay) in sacco ruminal degradation, ruminal fermentation characteristics, protozoal populations, milk production, and milk fatty acid (FA) profile in dairy cows was investigated. Four ruminally cannulated, primiparous lactating cows were used in a 4 × 4 Latin square design (28-d periods). They were fed a total mixed ration (50:50 forage:concentrate (F:C) ratio [dry matter (DM) basis] without supplementation (control, CTL), or supplemented (wt/wt; DM basis) with LO at 2, 3, or 4%. Supplementation with LO had no effect on DM intake (19 kg/d) and apparent total-tract digestibility of nutrients (organic matter, neutral detergent fiber, acid detergent fiber, starch, and gross energy). Ruminal pH, ammonia, and total volatile FA concentrations were not changed by LO supplementation to diets. Extent of changes in volatile FA pattern and effective ruminal degradability of DM of timothy hay were minor. Neither the total numbers nor the genera distribution of protozoa was changed by the addition of increasing amounts of LO to the diet. Milk yield increased linearly (26.1, 27.3, 27.4, and 28.4 kg/d for CTL to LO4, respectively) as the amount of LO added to the diet increased. Milk fat content was not affected by LO supplementation, whereas milk protein content decreased linearly with increasing amounts of LO in the diet. Milk fat proportions of several intermediates of ruminal biohydrogenation of polyunsaturated FA (i.e., trans-10 18:1, trans-11 18:1, cis-9,trans-11 18:2, trans-11,cis-15 18:2, and cis-9,trans-11,cis-15 18:3) increased linearly with LO addition to the diet. The proportion of cis-9,cis-12 18:2 decreased linearly (2.06, 1.99, 1.91, and 1.83% for CTL to LO4, respectively) as the amount of LO in the diet increased. Milk fat content of cis-9,cis-12,cis-15 18:3 increased as the level of LO in the diet increased up to 3% but no further increase was observed when 4% of LO was fed (0.33, 0.79, 0.86, and 0.86% for CTL to LO4, respectively). A similar quadratic response to LO supplementation was also observed for cis-5,cis-8,cis-11,cis-14,cis-17 20:5 and cis-5,cis-7,cis-10,cis-13,cis-16 22:5. The results of the present study show that LO can be safely supplemented up to 4% in forage-based diets of dairy cows to enrich milk with potential health beneficial FA (i.e., n-3 FA) without causing any detrimental effects on rumen function, digestion, and milk production.