We recently described helicobacter-associated progressive, proliferative, and dysplastic typhlocolitis in aging (18-to 24-month-old) Syrian hamsters. Other pathogens associated with typhlocolitis in hamsters, Clostridium difficile, Lawsonia intracellularis, and Giardia spp., were not indentified. The presence of Helicobacter genusspecific DNA was noted by PCR in cecal and paraffin-embedded liver samples from aged hamsters by the use of Helicobacter-specific PCR primers. By 16S rRNA analysis, the Helicobacter sp. isolated from the liver tissue was identical to the cecal isolates from hamsters. The six hamster 16S rRNA sequences form a genotypic cluster most closely related to Helicobacter sp. Flexispira taxon 8, part of the Helicobacter bilis/H. cinaedi group. Livers from aged helicobacter-infected hamsters showed various stages of predominantly portocentric and, to a lesser extent, perivenular fibrosis. Within nodules, there was cellular atypia consistent with nodular dysplasia. The livers also exhibited a range of chronic active portal/interface and lobular inflammation, with significant portal hepatitis being present. The inflammation was composed of a mixture of lymphocytes, neutrophils, and macrophages, indicative of its chronic-active nature in these aged hamsters infected with Helicobacter spp. The isolation of novel Helicobacter spp., their identification by PCR from the diseased livers of aged hamsters, and their taxonomic classification as belonging to the Helicobacter bilis cluster strengthen the argument that H. bilis and closely related Helicobacter spp. play an etiological role in hepatobiliary disease in both animals and humans.We recently described progressive, proliferative, and dysplastic typhlocolitis in aging (18-to 24-month-old) Syrian hamsters (31). The lesions in these hamsters were more severe in the older animals aged 7 to 24 months than in the younger, 1-to 6-month-old hamsters. The presence of Helicobacter spp. in the large bowel of all 24 hamsters included in the study was confirmed by culture and Helicobacter-specific PCR (31). Other pathogens associated with typhlocolitis in hamsters, Clostridium difficile, Lawsonia intracellularis, and Giardia spp., were not indentified in this study (31). Enterohepatic Helicobacter spp. are associated with the development of inflammatory bowel disease in mice and, as determined more recently, humans (2, 18, 27, 51). These helicobacters can also induce hepatitis and hepatocellular carcinoma in susceptible strains of mice (1,14,19). We undertook a study to examine in detail the histological profile of the livers of hamsters aged 18 to 24 months and to determine whether Helicobacter sp. DNA was present in their livers (31). In addition, we purchased a small number of 6-month-old hamsters from the same vendor which originally supplied the aged hamsters and examined them for the presence of Helicobacter spp. in their intestines and liver and whether inflammation was associated with the presence of Helicobacter spp. in these target tissues. We document t...
Abstract. The objective of this study was to evaluate stomachs of 2-year-old Syrian hamsters that were naturally colonized by multiple Helicobacter species including Helicobacter aurati. A previous report on 7-to 12-month-old Syrian hamsters described chronic gastritis and intestinal metaplasia, a putative preneoplastic lesion in the stomach, without cancer. This report describes an invasive adenocarcinoma at the pyloric-duodenal junction in one of nine hamsters at a site of helicobacter-associated inflammation and marked intestinal metaplasia. Ceca of nine of nine animals were culture positive and polymerase chain reaction positive for Helicobacter spp. Furthermore, immunohistochemical analysis of the stomach using a H. pylori polyclonal antibody detected positive-staining bacteria within the pyloric region of three of nine hamsters including the neoplastic glands. However, argyrophilic bacteria were demonstrated only within the stomach of the hamster with gastric adenocarcinoma. This is a first report of gastric adenocarcinoma in helicobacter-infected hamsters. Syrian hamsters appear suitable as potential model for studying development of helicobacter-associated gastric adenocarcinomas.Key words: Adenocarcinoma; gastritis; hamsters; Helicobacter; immunohistochemical; polymerase chain reaction; stomach.
Helicobacter spp. have been implicated in a variety of gastrointestinal tract diseases, including peptic ulcer disease, gastric cancer, and inflammatory bowel disease (IBD), in humans and animals. Although most models of IBD are experimentally induced, spontaneous or natural models of IBD are rare. Herein, we describe a long-term study of chronic, progressive lesions that develop in the distal portion of the large bowel of unmanipulated Syrian hamsters naturally infected with Helicobacter spp. Twenty-four Syrian hamsters of three age groups (group A, 1 month [n = 4], group B, 7-12 months [n = 12], group C, 18-24 months [n = 12]), underwent complete postmortem examination. Results of microbial isolation and polymerase chain reaction and restriction fragment length polymorphism analyses confirmed the presence of Helicobacter spp. infection in the distal portion of the large bowel of all animals. Additionally, confounding pathogens, such as Clostridium difficile, Lawsonia intracellularis, and Giardia spp. that can cause proliferative enteritis, were absent in the hamsters of this study. Histopathologic scores for inflammation (P < 0.01), hyperplasia (P < 0.01), and dysplasia (P < 0.05) were significantly higher in the ileocecocolic (ICC) junction of animals in group C, relative to group A. Dysplastic lesions of various grades were detected in 5 of 11 hamsters in group C. Interestingly, the segment of the bowel that is usually colonized by Helicobacter spp. in hamsters had the most severe lesions. One hamster of group C developed a malignant fibrous histiocytoma, whereas another hamster developed a round cell sarcoma originating from the ICC junction. Thus, lesions in the distal portion of the large bowel of aging hamsters naturally colonized with Helicobacter spp. warrants developing the hamster as an animal model of IBD and potentially IBD-related cancer.
A new family of polyanhydrides has been developed which can be cured photochemically to produce degradable networks. These degradable polyanhydride networks can be useful in orthopedics as bone cements and for drug delivery. This system, which is a semi-interpenetrating network (semi-IPN), has been evaluated for tissue compatibility in subcutaneous sites in rats and shown to undergo degradation by surface erosion. It was observed that the inflammatory response to the semi-IPN implants was minimal at both short (3, 6 weeks) and long (28 weeks) time points and the fibrotic response was largely absent throughout the duration of this study. Furthermore, excellent tissue infiltration and integration with good neovascularization was observed around the semi-IPN implants. The osteocompatibility and osteoconductive properties of this system have been evaluated in a longitudinal defect model in the articular surface of the distal femur in adult rabbits. This study compared the semi-IPN implants to control groups consisting of unfilled defects and PLA implants. Histological evaluation (H&E and Trichrome Masson staining) of the implant site revealed that the semi-IPN implant is osteocompatible and well tolerated by the surrounding cancellous bone and marrow constituents. The tissue reaction to the implant is characterized by an ingrowth of vascularized connective tissue and a mild fibrous capsule. Furthermore, partial to complete closure of the articular surface with fibrocartilage and fibrous tissue was observed in all experimental animals containing the semi-IPN polymer implants.
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