PubMed · 3245179
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E G Tkachenko, A L Fedushchak. 1988. [Morphologic changes due to injection trauma].. https://pubmed.ncbi.nlm.nih.gov/3245179/
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Decellularized tissues provide biological cues owing to the wealth of structural and regulatory factors that promote angiogenesis, adipogenesis, and myogenesis and facilitate neurite outgrowth. Here, we demonstrated the advantages of decellularized adipose tissue (adipoECM) over defined collagen-based biomaterials for host tissue integration. Three batches of human adipose tissue were decellularized using a rapid decellularization protocol and analyzed using mass spectrometry. To assess the biological activity of the decellularized materials, adipoECM and a reference standard of care biomaterial (Integra®DRT, also containing collagen I and glycosaminoglycans) were implanted subcutaneously, but far from the wound bed (in anatomical potential spaces) of immunocompetent BALB/c mice. The mice were euthanized in the acute (1 day) and chronic (day 60) inflammatory reaction phases, followed by biomaterial excision and Masson’s trichrome immunohistofluorescence imaging of the paraffin-embedded specimens. Each batch of processed tissue passed a quality control check, showing a low level of donor genomic DNA, lack of nuclei, lipids, endotoxins, and bacterial contamination. Mass spectrometry revealed that all batches of decellularized tissue mainly contained collagen I and, to a lesser degree, collagen III, collagen IV, collagen V, laminin, fibrillin, fibronectin, tenascin, and elastin. No acute inflammatory reaction was observed in either material one day post-transplantation. At 60 days post-implantation, different cell types were detected in adipoECM specimens, whereas Integra®DRT remained acellular. Additional immunohistochemical staining of adipoECM revealed CD31-positive cells in the blood vessels. Mesenchymal (CD90 positive) and myeloid (CD14 positive) cells were also detected. Primary cell types involved in soft tissue healing and remodeling were found in the adipoECM-treated group. The ingrowth of blood vessels and mesenchymal cells confirmed the effective integration of adipoECM with host tissues. Our results demonstrate that decellularized adipose tissue implanted away from the wound bed possesses contextual biological activities that promote efficient integration with host tissues.
Toxic equivalency factor (TEF) has been proposed to estimate the risk of polychlorinated biphenyl (PCB) congeners. However, ortho chlorine substitution in the two phenyl rings gives each PCB its own pattern of toxicity which is different from the mechanism of action of 2,3,7,8-tetrachlorodibenzo-p-dioxin. The present study evaluated the effect of prenatal and postnatal exposure to a low dose of the mono-ortho pentachlorobiphenyl PCB 118 on thyroid hormone concentrations and EROD activity in rats. Moreover, the tissue distribution of PCB 118 following one oral dose was evaluated. Sprague-Dawley rats were treated by gavage on GD 6 with 375 microg of PCB 118/kg b.w. Decreases in thyroxine and TSH levels were observed in dams at the end of lactation. Perinatal exposure to a low dose of PCB 118 permanently disrupted the hypothalamo-pituitary-thyroid (HPT) axis leading to a significant increase in thyroxine levels in offspring, as a 'thyroid resistance syndrome'. It is noteworthy that no changes in hepatic EROD activity were detected in dams at the end of lactation, even in the presence of high amounts of PCB in liver. Based on hepatic EROD activity (as a biomarker for aryl hydrocarbon receptor (AhR) induction), the mechanism of thyroid homeostasis disruption seems to be AhR-independent. Additionally, the 'thyroid resistance syndrome' observed in our study indicates the need for further detailed investigations on the HPT axis. We conclude that not only TEF, but also AhR-independent responses should be taken into account for risk assessment of mono-ortho PCB congeners.
A small percentage of mature mares continue to exhibit estrous cyclicity during the non-breeding season which is of interest because of the importance of timing of the breeding season to the equine breeding industry. Previously, it was demonstrated that the continuation of estrous cycles was more likely to occur in mature than young mares. Additionally, an apparent association exists between elevated body fat and increased circulating concentrations of leptin, and the occurrence of estrous cycles during the non-breeding season. Two experiments were conducted to test the hypothesis that pharmacological manipulation of body fat and leptin by administration of the beta(2)-adrenergic receptor agonist clenbuterol, with and without continuous treatment with melatonin, would increase the proportion of mares entering anestrus or advance its timing. In Experiment 1, eight mature mares were administered clenbuterol (3.2 microg/kg) daily from October through January and six mares were untreated. In Experiment 2, eight mares were administered clenbuterol daily from June through December, eight mares were treated with continuous release melatonin implants, and seven mares were treated with both clenbuterol and melatonin. Melatonin treatment was included to confirm previous results that constant treatment with melatonin did not advance the timing of anestrus. In both studies, leptin concentrations (P<0.01, both experiments) and body fat percentage (P<0.01, Experiment 1; P<0.05, Experiment 2) declined in response to daily clenbuterol treatment. Unexpectedly, however, this decrease was attenuated in mares also treated with melatonin (P<0.05). Although treatment with clenbuterol was associated with a decline in body fat and circulating concentrations of leptin, the timing or proportion of mares exhibiting anestrus was not modified (P>0.05). The results demonstrate the manipulation of body condition via pharmacological intervention does not modify the mechanisms controlling seasonal anestrus in the mare.