Structural Features of Connective Tissue Formed around Resin Implants Subcutaneously Embedded in Dairy Cows.

Foreign body reactions (FBRs) are inadvertently observed in invading or artificially embedded materials, triggering inflammation and subsequent fibrotic processes to occur in situ. Here, we assessed the spatiotemporal formation of connective tissue around implanted materials to establish a technique using connective tissue formed by FBRs as xenografts. An acrylic resin implant, comprising a columnar inner rod and a tubular outer cylinder (OC) with several slits, was embedded in adult dairy cows. Tissues formed in the inner rod and OC groups were histologically analyzed at weeks 2, 4, 8, and 12. Edematous tissues with non-collagenous fibers formed for 2 weeks and showed increased cellularity after 4 weeks. The weight, thickness, amounts of total protein, collagen, DNA, and quantitative scores of α-smooth muscle actin-positive myofibroblasts or elastic fibers notably increased after 8 weeks, with condensed collagen fibers showing orientation. Inflammatory cells were primarily localized in tissues close to the OC, and their numbers increased, with the count of CD204+ cells peaking at 8 weeks and declining at 12 weeks. The count of Ki67+ proliferating cells slightly increased in tissues close to the OC; however, the number and lumen of CD31+ vessels increased. These results may help understand FBR-related tissue remodeling.

Wall thickness control in biotubes prepared using type-C mold.

A type-C mold based on in-body tissue architecture was previously developed for preparing small-diameter biotube vascular grafts with a 2-mm diameter and approximately 1-mm wall thickness. In this study, the type-C mold was modified for preparing large-diameter biotubes with controlled wall thicknesses. Four types of molds were assembled by inserting silicone center rods (outer diameters 11, 13, 15, 17 mm) into stainless steel cages (inner diameter 19 mm) and surgically embedded in the abdominal subcutaneous pouches of Holstein cows. After 8-12 weeks, connective tissues occupied the rod-cage gap in the molds to form biotubes. The wall thickness of the biotubes obtained after removing the molds was approximately 1-3 mm, which corresponded to approximately 80% of each gap distance. The breaking strength almost linearly increased with the wall thickness of the biotubes. The strength of the biotubes with wall thickness over 1.5 mm was higher than that of beagle blood vessels. The thickest biotubes were as strong as bovine pericardium and can be used as an alternative trachea graft because of their adequate lumen-holding force.

Degenerative and regenerative features of myofibers differ among skeletal muscles in a murine model of muscular dystrophy.

Skeletal muscle myofibers constantly undergo degeneration and regeneration. Histopathological features of 6 skeletal muscles (cranial tibial [CT], gastrocnemius, quadriceps femoris, triceps brachii [TB], lumbar longissimus muscles, and costal part of the diaphragm [CPD]) were compared using C57BL/10ScSn-Dmd mdx (mdx) mice, a model for muscular dystrophy versus control, C57BL/10 mice. Body weight and skeletal muscle mass were lower in mdx mice than the control at 4 weeks of age; these results were similar at 6-30 weeks. Additionally, muscular lesions were observed in all examined skeletal muscles in mdx mice after 4 weeks, but none were noted in the controls. Immunohistochemical staining revealed numerous paired box 7-positive satellite cells surrounding the embryonic myosin heavy chain-positive regenerating myofibers, while the number of the former and staining intensity of the latter decreased as myofiber regeneration progressed. Persistent muscular lesions were observed in skeletal muscles of mdx mice between 4 and 14 weeks of age, and normal myofibers decreased with age. Number of muscular lesions was lowest in CPD at all ages examined, while the ratio of normal myofibers was lowest in TB at 6 weeks. In CT, TB, and CPD, Iba1-positive macrophages, the main inflammatory cells in skeletal muscle lesions, showed a significant positive correlation with the appearance of regenerating myofibers. Additionally, B220-positive B-cells showed positive and negative correlation with regenerating and regenerated myofibers, respectively. Our data suggest that degenerative and regenerative features of myofibers differ among skeletal muscles and that inflammatory cells are strongly associated with regenerative features of myofibers in mdx mice.

Acute colic possibly caused by phytobezoar derived from napier grass in 5 Japanese black cows reared in the same farm.

For 6 years, 5 Japanese Black cows of the same herd showed anorexia, depression, and dehydration with no feces in the rectum. Biomedical examination of 3 animals showed severe hypokalemia and hypochloremia. Although the first 3 animals died or were slaughtered (causes unknown), necropsy results showed that the cow in case 4 had intestinal obstruction due to phytobezoar derived from napier grass, fed mainly to the cattle as roughage. Therefore, farmers were recommended to avoid the hard root-stem portion of napier grass as roughage. Consequently, less phytobezoar was recovered from the fifth cow, and no similar clinical case of intestinal obstruction was observed thereafter. This is the first report on intestinal obstruction caused by phytobezoars derived from napier grass.

Expression of caspase family and muscle- and apoptosis-specific genes during skeletal myogenesis in mouse embryo.

The caspases (Casps) are a family of cysteine proteases that are known to regulate apoptotic signaling. Apoptosis by activation of Casp is strongly associated with embryonal development and regeneration in many organs, therefore indicating that disorders caused by homozygous mutation in Casp genes can result in embryonic lethality. In the present study, the authors investigated the causative relationship between skeletal myogenesis and the activation of Casps by analyzing their dynamics during mouse embryogenesis. Individual myogenetic tissues were obtained from C57BL/6 mouse embryos aged 12.5-17.5 days post-conception (dpc), and the expression of Casps was analyzed by histochemical and molecular biological methods. Immunoreactions for Casp-3, -9 and -12 were detected first in myoblasts, increasing according to embryonal development, as a result of which myoblasts differentiated into myotube cells. On the other hand, the immunoreaction for ssDNA, which is well-known as an apoptosis marker, was little detected during the skeletal myogenesis. Quantification analysis for Casp mRNA expression by RT-PCR as well as by in situ hybridization showed a peak at 15.5 dpc but a decrease at 17.5 dpc. Similar dynamics were detected for Myod1 mRNA, one of the muscle regulatory factors, but not for Fasl, Bax and Rock1, apoptosis-associated factors during skeletal myogenesis. These results suggest that the activation of Casps in skeletal myogenesis is deeply associated with myoblast differentiation, but not directly related to apoptosis.