A total of 1,496 rodents and insectivores were live-trapped at Yeoncheon-gun (n = 351), Paju-shi (804), and Pocheon-gun (343), Gyeonggi-do (Province), and examined for intestinal helminths, including Neodiplostomum seoulense, seasonally from December 2004 to September 2005. Six species of rodents, including Apodemus agrarius (1,366), Mus musculus (32), Micronytus fortis (28), Eothenomys regulus (9), Micronys minutus (6), and Cricetulus triton (3), and 1 species of insectivores Crocidura lasiura (54) were collected. A total of 321 adult N. seoulense were collected from 19 (1.4%) A. agrarius. The worm burden ranged from 1 to 101 per A. agrarius (mean; 16.9). No N. seoulense was observed in other rodent or insectivore species examined. The infection rate during autumn (4.5%) was higher than those during spring (0.8%), summer (0.8%), and winter (0.5%). The average number of N. seoulense in infected A. agrarius was the highest in spring (66.0 specimens), followed by autumn (15.2), winter (4.5), and summer (3.3). This study first confirms that A. agrarius is a natural definitive host for N. seoulense, and demonstrates that the infection rates and intensities vary seasonally and geographically.
Animals ; Arvicolinae/parasitology ; Cricetinae ; Cricetulus/parasitology ; Feces/parasitology ; Geography ; Insectivora/parasitology ; Intestine, Small/parasitology ; Korea/epidemiology ; Mice ; Murinae/*parasitology ; Rodent Diseases/*epidemiology ; Seasons ; Trematoda/*isolation & purification ; Trematode Infections/epidemiology/*veterinary

The small intestines of 6 species of rodents and 1 species of insectivore were examined seasonally for Plagiorchis muris infection in 3 different localities in northern Gyeonggi-do (Province), near the demilitarized zone (DMZ). A total of 1,496 animals, including 1,366 Apodemus agrarius, 54 Crocidura lasiura (insectivore), 32 Mus musculus, 28 Micronytus fortis, 9 Eothenomys regulus, 6 Micronys minutus, and 3 Cricetulus triton, were live-trapped at Yeoncheon-gun (n = 351), Paju-shi (804) and Pocheon-gun (343) at 3-mo intervals from December 2004 to September 2005. A total of 1,647 P. muris were collected from 72 (5.3%) A. agrarius. The infection rate was the highest in Pocheon-gun (8.2%), followed by Yeoncheon-gun (5.0%) and Paju-shi (4.2%). A higher infection rate was observed in A. agrarius captured during September (19.4%) than those captured during December (3.0%), June (2.6%), or April (0%). However, the worm burden was the highest in June (av. 32.1/animal), followed by September (24.7), December (4.0), and April (0). None of the other animal species were found infected with P. muris. The results reveal that A. agrarius is a natural definitive host for P. muris, and infection rates and worm burdens vary seasonally and geographically.
Animals ; Arvicolinae/parasitology ; Cricetinae ; Cricetulus/parasitology ; Insectivora/parasitology ; Intestine, Small/parasitology ; Korea/epidemiology ; Mice/parasitology ; Murinae/*parasitology ; Prevalence ; Rodent Diseases/epidemiology/*parasitology ; Rodentia ; Seasons ; Trematoda/*isolation & purification ; Trematode Infections/epidemiology/parasitology/*veterinary

OBJECTIVETo investigate differences between hepatic and biliary lipid metabolism and secretion of genetically gallstone-susceptible (C57L) and resistant (AKR) mice and the mechanism of cholesterol gallstone formation.

METHODSThe inbred C57L and AKR mice were fed a lithogenic diet containing 15% fat, 1.25% cholesterol and 0.5% cholic acid for four weeks. Hepatic cholesterol content and secretion rates of biliary lipids, as well as phenotypes of the liver and gallbladder were determined and examined before and after the feeding of the lithogenic diet.

RESULTSBoth before and after ingestion of the lithogenic diet, hepatic secretion rates of all biliary lipids in C57L mice were markedly higher than that of AKR mice (P < 0.05, P < 0.01, respectively), whereas hepatic cholesterol contents of C57L mice were significantly lower than that of AKR mice (P < 0.05). Furthermore, after consumption of the lithogenic diet, the increase in hepatic secretion rate of biliary cholesterol in C57L mice was significantly higher than that in AKR mice (P < 0.01). Cholesterol gallstones formed in C57L mice and fatty livers developed in AKR mice.

CONCLUSIONSBiliary cholesterol hypersecretion is the key pathophysiological defect of gallstone formation, lith genes have effects on biliary cholesterol hypersecretion and susceptibility to cholesterol gallstone formation in C57L mice. Lithogenic bile is formed at the canalicular membrane and precedes the development of cholesterol gallstones. It is most likely that cholesterol and bile acid hyposecretion make the AKR strain susceptible to the development of fatty livers and resistant to gallstone formation.

Animals ; Bile ; metabolism ; Cholelithiasis ; genetics ; metabolism ; Cholesterol ; analysis ; metabolism ; Fatty Liver ; etiology ; Genetic Predisposition to Disease ; Lipid Metabolism ; Liver ; metabolism ; Male ; Mice ; Mice, Inbred AKR ; Mice, Inbred C57BL

Otitis media (OM) is one of the most common inflammatory illnesses in the pediatric population. OM is a multifactorial disease that develops as a result of complex interactions between bacterial infection, environmental risk factors, and host genetic factors. The high prevalence and recurrence of OM, coupled with the risk of developing hearing loss have meant that research to understand the mechanisms of OM and identify new therapeutic measures is urgent. Various experimental animals such as chinchilla, guinea pig, gerbil, rat and mouse have been used to investigate the pathogenesis and treatment of OM. Also, a lot of methods have been introduced to induce OM in animals including obstruction of E tube and direct injection of otopathogens into the middle ear. Recently there has been an increase in the use of the mouse for OM research due to the ability to easily manipulate their genetic components. The use of animal models has enabled researchers to identify a number of molecular mechanisms involved in the development of OM. Despite the real progresses obtained from animal models of OM, however, there are still several limitations to using them for OM research. In this review article, various animal models that have been introduced to investigate the pathogenesis of OM will be discussed briefly.
Animals ; Bacterial Infections ; Chinchilla ; Ear, Middle ; Gerbillinae ; Guinea Pigs ; Hearing Loss ; Mice ; Models, Animal* ; Otitis Media* ; Prevalence ; Rats ; Recurrence ; Risk Factors

BACKGROUND AND OBJECTIVES: Mucosal surfaces in the middle ear and eustachian tube are protected by several complex defense mechanisms, namely mucociliary clearance, immunoglobulins, cellular components, and antibacterial secretory enzymes. The secretory enzymes such as lysozyme and lactoferrin are found in various mucosal tissues and most of body secretions which cover the human mucosal surfaces. Because of their bactericidal activity, it has been suggested that these enzymes contribute to the defense against local mucosal infections. It has been known that lysozyme- and lactoferrin-secreting cells in tubotympanum were various in species such as human, chinchilla, guinea pig and Mongolian gerbil. The purpose of this study is to identify and localize the lysozyme- and lactoferrin-secreting cells in the eustachian tube of normal mice using histochemical and immunohistochemical techniques. MATERIALS AND METHODS: Normal mice (BALB/c, 60-120 days old, 10 heads) were used for staining of tubotympanum with hematoxylin-eosin stain, Alcian blue-periodic acid-Schiff (AB-PAS) stain and immunohistochemical stain (antihuman lysozyme, and antihuman lactoferrin antibodies). RESULTS: 1) Secretory cells in the epithelium and subepithelial glands are observed more in the pharyngeal portion than in the tympanic portion of eustachian tube. Subepithelial glands are also noted more in lower part than in upper part of eustachian tube. 2) Lysozyme was observed in the secreting cells of mucosal epithelium and the serous cells of subepithelial glands. 3) Lactoferrin was observed in the serous cells of subepithelial glands, but not in the epithelium. CONCLUSION: In the eustachian tube of BALB/c mouse, lysozyme and lactoferrin were detected in the serous cells in subepithelial glands and only lysozyme is observed in the secretory cells in the eustachian tube epithelium.
Animals ; Chinchilla ; Defense Mechanisms ; Ear, Middle ; Epithelium ; Eustachian Tube* ; Gerbillinae ; Guinea Pigs ; Humans ; Immunoglobulins ; Lactoferrin ; Mice* ; Mucociliary Clearance ; Mucous Membrane ; Muramidase

Animals ; Cholelithiasis ; genetics ; Cholesterol ; metabolism ; Cholesterol 7-alpha-Hydroxylase ; genetics ; Genetic Predisposition to Disease ; Hydroxymethylglutaryl CoA Reductases ; genetics ; Liver ; enzymology ; Male ; Mice ; Mice, Inbred AKR ; Mice, Inbred C57BL ; Receptors, LDL ; genetics ; Sterol O-Acyltransferase ; genetics

Members of the genus Trichinella are small nematodes that can infect a wide range of animal hosts. However, their infectivity varies depending on the parasite and host species combination. In this study, we examined the susceptibility of 4 species of laboratory rodents, i.e., mice, rats, hamsters, and gerbils to Trichinella papuae, an emerging non-encapsulated Trichinella species. Trichinella spiralis and Trichinella pseudospiralis were also included in this study for comparison. Fifteen animals of each rodent species were infected orally with 100 muscle larvae of each Trichinella species. Intestinal worm burden was determined at day 6 and 10 post-inoculation (PI). The numbers of muscle larvae were examined at day 45 PI. The reproductive capacity index (RCI) of the 3 Trichinella species in different rodent hosts was determined. By day 6 PI, 33.2-69.6% of the inoculated larvae of the 3 Trichinella species became adult worms in the small intestines of the host animals. However, in rats, more than 96% of adult worms of all 3 Trichinella species were expelled from the gut by day 10 PI. In gerbils, only 4.8-18.1% of adult worms were expelled by day 10 PI. In accordance with the intestinal worm burden and the persistence of adults, the RCI was the highest in gerbils with values of 241.5+/-41.0 for T. papuae, 432.6+/-48 for T. pseudospiralis, and 528.6+/-20.6 for T. spiralis. Hamsters ranked second and mice ranked third in susceptibility in terms of the RCI, Rats yielded the lowest parasite RCI for all 3 Trichinella species. Gerbils may be an alternative laboratory animal for isolation and maintenance of Trichinella spp.
Animals ; *Animals, Laboratory ; Cricetinae ; *Disease Susceptibility ; Gerbillinae ; Intestines/parasitology ; Male ; Mice ; Muscles/parasitology ; Parasite Load ; Rats ; Rodent Diseases/*parasitology/pathology ; Trichinella/*growth & development ; Trichinellosis/parasitology/pathology/*veterinary

OBJECTIVETo understand the distribution, fauna, population structure of host animals and their parasitic fleas as well as popular dynamic of animal plague of natural plague foci in Junggar Basin.

METHODSSample materials and data of animals and vector insects were collected using ecological methods and the population structures were analyzed statistically. F1 antibody of Yersinia pestis in rodents' serum and organ suspension was detected by means of IHA while the pathogen of Y. pestis in rodents and vector insects was detected by means of aetiological detections and the isolated Y. pestis was detected using biochemical methods.

RESULTSThe small mammals which were found in Junggar Basin belonged to 17 species of 11 genera 7 families. Of them, 13 species of rodents were included whose parasitic fleas belonged to 19 species of 10 genera 8 families. The average coverage of Rhombomys opimus hole-community was 22.5% in Junggar Basin with the average density of R. opimus hole-community was 15.9/hm2 and the average rate of habitat of the hole-community was 70.2%. In the R. opimus community, the average density of rodents was 3.1/hole-community, and 34.4/hm2 in the nature plague foci. In the population structure of the hole-community of R. opimus, R. opimus accounted for 72.9% in the total captured rodents, Meriones meridianus was 24.5% while the others were 2.6%. In the nocturnal community of rodents, M. meridianus accounted for 64.0% in total captured rodents, Dipus sagitta was 15.1%, M. erythrourns was 7.5% and the others were 13.4%. In the rodents community of Junggar Basin, the rate of R. opimus with fleas was 84.9%, which was the highest, followed by M. tamariscinus, Euchoreutes naso and M. erythrourns, with the rates as 71.4%, 66.7% and 62.7% respectively. The rate of M. meridianus with fleas was 38.3%. There were 16 species of parasitic fleas in R. opimus, with the total flea index as 8.58 and the dominant species was Xenopsylla skrjabini. There were 17 and 16 kinds of fleas in M. erythrourns and M. meridianus respectively with the total flea index were 1.59 and 1.15, with dominant fleas were Nosopsyllus laeviceps and X. skrjabini. The serum and organ suspension of 3179 rodents which belonged to 12 species were detected by means of IHA, of them 174 samples were positive and the positive rate was 5.5%. There were 1356 samples of R. opimus in these materials, and 164 were positive, accounted for 12.1%. The samples of M. meridianus were 1255, with 9 positive, accounted for 0.7%. The samples of D. sagitta were 116 with 1 positive and the rate was 0.9%. The samples of other rodents were 452 but were all negative. There were in total 2975 organs collected from rodents, when detected by methods of isolated of Y. pestis. 15 strains of Y. pestis were isolated from 1243 R. opimus, and 2 strains isolated from 1230 M. meridianus. A total number of 11 647 fleas from rodents were detected by methods of isolated of Y. pestis in which 1 strain of Y. pestis was isolated from 4713 X. skrjabini, and 6 were isolated from 2101 Xenopsylla minax, 1 from 328 Xenopsylla conformis conformis and 1 from 250 Echidnophaga oschanini. Among the other 4255 fleas, none was isolated. The biochemical properties of these Y. pestis which isolated from Junggar Basin were positive of Maltose, Ejiao sugar and Glycerol, and negative of Rhamnose and Nitrogen, which were all strongly poisonous to mouse.

CONCLUSIONThe natural plague foci in Junggar Basin spread all over the whole Junggar Basin. There were animal plague cases found in 12 counties (cites) while Karamy, Bole, Jimusaer and Qitai were confirmed as plague foci counties (cities). Animals and vector insects of the foci were complicated but the ecological system was stable. R. opimus was recognized as the dominant host animal and its biochemical type belonged to the Middle Ages, suggesting that the foci was a new type of natural plague foci.

Animals ; China ; epidemiology ; Gerbillinae ; microbiology ; Mice ; Plague ; epidemiology ; microbiology ; Rodent Diseases ; epidemiology ; microbiology ; Yersinia pestis ; immunology ; pathogenicity

BACKGROUND: Many animals such as chinchilla, guinea pig, rat and rabbit have been used for study of the otitis media and their morphology of the eustachian tube are well known. However, it is not easy to use these animals in Korea. Therefore, active morphological study of the eustachian tube related to otitis media have not been performed. The Mongolian gerbil is an easily maintained rodent which has been useful for investigations of the ear canal cholesteatoma and inner ear. However, histologic study of the eustachian tube of Mongolian gerbil has not been established. OBJECTIVES: The purpose of this study was to describe the light microscopic morphology and the ultrastructure of the eustachian tube in Mongolian gerbil in order to prepare basic morphological data for the future animal study concerning pathogenesis of otitis media. MATERIALS & METHOD: Eight normal adult(90 to 120 days old) Mongolian gerbils(16 ears) were used for this study. Eustachian tube specimen was obtained after perfusion fixation and fixed. After 3 weeks of decalcification, paraffin block and EPON 812 block were made and sectioned. Those were observed under light microscope and transmission electron microscope. RESULTS: The cartilage and muscular structure(tensor veli palatini muscle, levator veli palatini muscle) of the eustachian tube of Mongolian gerbil were similar to those of other experimental animals. The total length of eustachian tube of Mongolian gerbil was relatively short and natural infection was rare.In the epithelium of the eustachian tube of Mongolian gerbil, four types of epithelial cells, ie ciliated, nonciliated, secretory cells and basal cells were identified like other experimental animals. On transmission electron microscopic findings, three types of secretory cells, ie, dark granulated, light granulated and mixed granulated cells were observed. The subepitheial glandular structure was observed along the whole length of eustachian tube. CONCLUSION: In this study, we found that the morphology of the eustachian tube of Mongolian gerbil was similar to those of other experimental animals such as chinchilla, guinea pig, rat and we recognized that Mongolian gerbil is possible to be used as a good experimental model of eustachian tube study for otitis media research.
Animals ; Cartilage ; Chinchilla ; Cholesteatoma ; Ear Canal ; Ear, Inner ; Epithelial Cells ; Epithelium ; Eustachian Tube* ; Gerbillinae* ; Guinea Pigs ; Korea ; Models, Theoretical ; Otitis Media ; Paraffin ; Perfusion ; Rats ; Rodentia

Chigger mites are parasites of rodents and other vertebrates, invertebrates, and other arthropods, and are the only vectors of scrub typhus, in addition to other zoonoses. Therefore, investigating their distribution, diversity, and seasonal abundance is important for public health. Rodent surveillance was conducted at 6 districts in Shandong Province, northern China (114–112°E, 34–38°N), from January to December 2011. Overall, 225/286 (78.7%) rodents captured were infested with chigger mites. A total of 451 chigger mites were identified as belonging to 5 most commonly collected species and 3 genera in 1 family. Leptotrombidium scutellare and Leptotrombidium intermedia were the most commonly collected chigger mites. L. scutellare (66.2%, 36.7%, and 49.0%) was the most frequently collected chigger mite from Apodemus agrarius, Rattus norvegicus, and Microtus fortis, respectively, whereas L. intermedia (61.5% and 63.2%) was the most frequently collected chigger mite from Cricetulus triton and Mus musculus, respectively. This study demonstrated a relatively high prevalence of chigger mites that varied seasonally in Shandong Province, China.
Animals ; Arthropods ; Arvicolinae ; China* ; Cricetinae ; Cricetulus ; Humans ; Invertebrates ; Mice ; Mites* ; Murinae ; Neptune ; Parasites ; Prevalence ; Public Health ; Rats ; Rodentia* ; Scrub Typhus ; Seasons ; Trombiculidae* ; Vertebrates ; Zoonoses