Down's syndrome (DS) in humans is caused by trisomy of chromosome 21 (HSA 21). DS patients have a variety of pathologies, including mental retardation and an unusually high incidence of leukemia or lymphoma such as megakaryocytic leukemia. Individuals with DS develop the characteristic neuropathological hallmarks of Alzheimer's disease (AD) in early adulthood, generally by the fourth decade of life. There are several mouse models of DS that have a segmental trisomy of mouse chromosome 16 (MMU 16) with triplicated genes orthologous to HSA 21. These mice display neurodegeneration similar to DS. Although brain pathology in DS models is known, little information is available about other organs. We studied the extraneural pathology in aged DS mice (Ts65Dn, Ts2 and Ts1Cje aged 8 to 24 months) as well as other mouse models of neurodegeneration, including presenilin (PS), amyloid-β precursor protein (APP), and tau (hTau and JNPL) transgenic mice. An increased incidence of peripheral amyloidosis, positive for amyloid A (AA) but not amyloid-β peptide (Aβ), was found in APP over-expressing and tauopathic mice as compared to nontransgenic (ntg) littermates or to DS mouse models. A higher incidence of lymphoma was found in the DS models, including Ts1Cje that is trisomic for a small segment of MMU 16 not including the App gene, but not in the APP over-expressing mice, suggesting that high APP expression is not the cause of lymphoma in DS. The occurrence of lymphomas in mouse DS models is of interest in relation to the increased incidence of malignant conditions in human DS.
Objective The purpose of this work was to develop an animal model of sclerosing encapsulating peritonitis, a complication of continuous ambulatory peritoneal dialysis in which the intestines are conglomerated into an ovoid cocoonlike structure. Design Toward this end, rats were injected with a chemical irritant (household bleach) intraperitoneally. One week later, before the resultant peritonitis could cause adhesions, 10 or 25 mL of fresh whole rat blood was injected into the peritoneal cavity. Two weeks later, the effect of the treatments was evaluated by macroscopic and microscopic study. Results The irritant caused a chemical peritonitis. The subsequently injected blood clotted on the surfaces of the inflamed intestines, and contraction of the clot (syneresis) was responsible for bringing the intestinal loops together. This conglomeration was made permanent by the fibrosis evoked by the chemical peritonitis. The end result was an ovoid encapsulated mass of intestines and other viscera. Conclusion An animal model for an abdominal cocoon has been produced. It can be used for studies of the pathogenesis and prevention of this complication of peritoneal dialysis.
Large doses of pyridoxine cause injury to the primary sensory neurons in trigeminal and dorsal root ganglia of animals and patients subjected to megavitamin therapy. The increased hazard to subjects with reduced renal excretory function has been explored previously. In the present work, the neurotoxicity of pyridoxine for rats was found to be increased by dietary protein deficiency. A mere 3 or 7 days of pretreatment with either of two protein-deficient diets were sufficient to accelerate and intensify the clinical neurological signs and histological lesions from pyridoxine injections. These results are caused, at least in part, by loss of body weight, decreased protein binding in serum and decreased consumption of water and decreased volume of urine, which reduce the urinary losses of the toxicant. The vitamers related to pyridoxine (pyridoxal, pyridoxamine) and the coenzyme (pyridoxal 5-phosphate) did not cause clinical signs or lesions similar to those produced by pyridoxine even when injected in maximum tolerated doses. Neither a protein-deficient diet nor bilateral nephrectomy changed the results with the vitamers.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.