The sheep is becoming increasingly used as a large animal model for preclinical spine surgery studies. Access to the ovine lumbar intervertebral discs has traditionally been via an anterior or anterolateral approach, which requires larger wound incisions and, at times, significant abdominal retraction. We present a new minimally invasive operative technique for a far-lateral approach to the ovine lumbar spine that allows for smaller incisions, excellent visualisation of intervertebral discs, and minimal abdominal retraction and is well tolerated by animals with minimal morbidity.
High-heat processed foods contain proteins that are partially resistant to enzymatic digestion and pass through to the colon. The fermentation of resistant proteins by gut microbes produces products that may contribute to chronic disease risk. This pilot study examined the effects of a resistant protein diet on growth, fecal microbiome, protein fermentation metabolites, and the biomarkers of health status in pigs as a model of human digestion and metabolism. Weanling pigs were fed with standard or resistant protein diets for 4 weeks. The resistant protein, approximately half as digestible as the standard protein, was designed to enter the colon for microbial fermentation. Fecal and blood samples were collected to assess the microbiome and circulating metabolites and biomarkers. The resistant protein diet group consumed less feed and grew to ~50% of the body mass of the standard diet group. The diets had unique effects on the fecal microbiome, as demonstrated by clustering in the principal coordinate analysis. There were 121 taxa that were significantly different between groups (adjusted-p < 0.05). Compared with control, plasma tri-methylamine-N-oxide, homocysteine, neopterin, and tyrosine were increased and plasma acetic acid was lowered following the resistant protein diet (all p < 0.05). Compared with control, estimated glomerular filtration rate (p < 0.01) and liver function marker aspartate aminotransferase (p < 0.05) were also lower following the resistant protein diet. A resistant protein diet shifted the composition of the fecal microbiome. The microbial fermentation of resistant protein affected the levels of circulating metabolites and the biomarkers of health status toward a profile indicative of increased inflammation and the risk of chronic kidney disease.
Characterisation of germinal centre B and T cell responses yields critical insights into vaccine immunogenicity. Non-human primates are a key pre-clinical animal model for human vaccine development, allowing both lymph node and circulating immune responses to be longitudinally sampled for correlates of vaccine efficacy. However, patterns of vaccine antigen drainage via the lymphatics after intramuscular immunisation can be stochastic, driving uneven deposition between lymphoid sites, and between individual lymph nodes within larger clusters. In order to improve the accurate isolation of antigen-exposed lymph nodes during biopsies and necropsies, we developed and validated a method for co-formulating candidate vaccines with tattoo ink, which allows for direct visual identification of vaccine-draining lymph nodes and evaluation of relevant antigen-specific B and T cell responses by flow cytometry. This approach improves the assessment of vaccine-induced immunity in highly relevant non-human primate models.
Characterization of germinal center B and T cell responses yields critical insights into vaccine immunogenicity. Nonhuman primates are a key preclinical animal model for human vaccine development, allowing both lymph node (LN) and circulating immune responses to be longitudinally sampled for correlates of vaccine efficacy. However, patterns of vaccine Ag drainage via the lymphatics after i.m. immunization can be stochastic, driving uneven deposition between lymphoid sites and between individual LN within larger clusters. To improve the accurate isolation of Ag-exposed LN during biopsies and necropsies, we developed and validated a method for coformulating candidate vaccines with tattoo ink in both mice and pigtail macaques. This method allowed for direct visual identification of vaccine-draining LN and evaluation of relevant Ag-specific B and T cell responses by flow cytometry. This approach is a significant advancement in improving the assessment of vaccine-induced immunity in highly relevant nonhuman primate models.
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