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Biomedical subjects

R M Chu

Publications and source records attributed to R M Chu.

32 records · Page 2Linked to original sources
PubMed1984

Morphological and functional comparisons of Peyer's patches in different parts of the swine small intestine.

Fifteen conventional 8-week-old pigs were used to compare the morphology and function of Peyer's patches (PP) in different parts of the small intestine with special emphasis on the dome epithelium (DE). The comparisons were done by morphological observation through light and electron microscopy, and by the ability of the DE complex to phagocytize horseradish peroxidase (HRP). Dome epithelium of the PP in the jejunum was more superficially located in the mucosa in comparison with the ileum. The DE's of the ileum were much smaller, with an area of 3.7 micron2/DE, than that of the jejunum (18.4 micron2/DE). The number of DE areas/5 cm2 in the ileum was more than in the jejunum. However, the total surface area of DE/5 cm2 of PP, was larger in the jejunum (180.5 micron2) than in the ileum (55.6 micron2). Brown discoloration of diaminobenzidine-hydrogenperoxide (DAB+H2O2)-treated PP specimens, after HRP inoculation, intensified with post-inoculation time from 20 s to 5 min. The brown pigment first appeared on the surface of microvilli and infiltrated into the dome. No morphological differences were observed between the jejunum and the ileum in 1 micron thick Epon-embedded specimens. Intramucosally, brown pigment was almost always found in DE areas. The pigmented areas were more numerous in the jejunum but the color intensity showed no obvious difference. By transmission electron microscopy, the electron dense materials (which were interpreted as the products of HRP and DAB+H2O2) were found between the microvilli of membraneous (M) cells, in the intercellular spaces of the DE, and in a form similar to intracytoplasmic vesicles in the cytoplasm of M-cell and DE complex lymphocytes. Our results confirmed that DE of PP had much stronger phagocytic activity than did the ordinary villous epithelium. This evidence indicates that the DE complex of PP in the swine intestine is immunologically important.

Animals↗
PubMed1983

Cryptosporidiosis in domestic birds.

From March to June 1982, three cases of avian cryptosporidiosis were encountered in chickens, ducklings, and canaries. The bursa of Fabricius of chickens and ducklings were the main target organs and the agents were found to attach the microvillus border of the plical epithelium. In canaries, the parasites adhered to the microvillus border of mucosal epithelium of the proventriculus. Diagnoses were based on the microscopic pathology, the morphology of the parasites, and the type of attachment to epithelium. This represents the first authenticated evidence of cryptosporidial infection in Taiwan.

Animals↗
PubMed1982

Applications of peroxidase-antiperoxidase staining technique for detection of transmissible gastroenteritis virus in pigs.

The peroxidase-antiperoxidase (PAP) staining technique was used for the detection of transmissible gastroenteritis virus (TGEV) in small intestines of TGEV-infected 8-week-old pigs and in infected McClurkin pig testicle cells by means of light microscopy. The specific-positive reaction was characterized by the presence of many brown granules of various sizes in the cytoplasm of infected cells. Nonspecific granules caused by endogenous peroxidases in the cytoplasm of eosinophils stained by PAP were darker, larger, more round, and more uniform in size than were specific granules. Acetone fixation was superior to fixation with periodate-lysine-paraformaldehyde or 10% formalin. Our results indicate that the PAP staining technique is a sensitive, specific technique for detection of TGEV in the small intestines of pigs.

Animals↗
PubMed1982

Isolation and identification of swine rotavirus in Taiwan.

Large numbers of viral particles resembling rotavirus were detected with negative stained electron microscopy in bacteria free fecal filtrate obtained from 10-day old diarrheal suckling piglets of a conventional pig farm in Taiwan. The clinical signs of vomiting and diarrhea were reproduced in colostrum deprived piglets artificially infected with the fecal filtrates. Rotavirus particles persisted in the fecal samples after two in vivo serial passages, and was not seen in the uninfected control animal. The Cytoplasm of infected jejunal and ileal enterocyte fluoresced when standard anti-porcine rotavirus conjugate was applied in an direct immunofluorescent staining test. In the experimentally infected piglets, moderate villous atrophy of the small intestine was the main microscopic lesion observed. The virus was identified by the above evidence to be rotavirus.

Animals↗
PubMed1982

Changes in gut-associated lymphoid tissues of the small intestine of eight-week-old pigs infected with transmissible gastroenteritis virus.

The responses of the interepithelial lymphocytes (IEL) and aggregated lymph nodules (ALN; Peyer's patches) of the small intestines of 8-week-old pigs to transmissible gastroenteritis virus (TGEV) infection were characterized at 12, 18, and 24 hours after pigs were inoculated. There was no significant difference in numbers of IEL between control and TGEV-infected pigs at 12 and 18 hours. However, in pigs examined at 24 hours, there was a significant decrease in the number of IEL in the duodenum and cranial portion of the jejunum and an increase of IEL numbers in the nuclear level of the intestinal epithelium. Number and distribution were unchanged in the middle portion of the jejunum and the ileum. Microscopic changes in TGEV-infected pigs included microulceration of the dome epithelium (DE) over the ALN, especially in the cranial portion of the intestine, and villous atrophy in the entire length of the small intestine. Generally, TGEV was found by means of peroxidase-antiperoxidase staining in areas where microscopic lesions occurred. Electron microscopy revealed that M cells and ordinary microvillus-covered epithelial cells in the DE embraced one or more lymphocytes, and formed a specialized cell complex or DE complex. Most of the lymphocytes in the DE complex possessed many organelles indicative of an active cell state. The TGEV was found between microvilli, in the cytoplasmic vesicles of M cells and microvillus-covered epithelial cells in the DE, and in the cytoplasm of macrophages and lymphocytes and some degenerated cells of unidentified origin in the domes of the ALN. The virus was also commonly found in cytoplasmic vesicles of macrophages and degenerated cells in the intestinal lumen near the base of the dome of the ALN.

Animals↗
PubMed1980

Placental lesions caused by pseudorabies virus in pregnant sows.

Pathologic and viral investigations were done on 13 fetal placentas and 23 aborted fetuses associated with naturally occurring pseudorabies in swine. Of the 13 fetal placentas examined, 7 (53.8%) had various degrees of necrotizing placentitis. The lesions were characterized by coagulative necrosis of the chorionic fossae and by intranuclear inclusions in degenerating trophoblasts and occasionally in mesenchymal cells. In addition, a mild inflammatory cell reaction was observed in the mesenchyma. Numerous viral particles, ultrastructurally indistinguishable from herpesvirus, were observed by electron microscopy in the affected chorionic membrane. Large aggregates of herpesvirus virions were demonstrated in the nucleus and cytoplasm of degenerated trophoblasts and mesenchymal cells. Of the 23 aborted fetuses examined, 22 (95.6%) had typical coagulative necrosis in the liver, spleen, adrenal glands, and visceral lymph nodes. Inclusions similar to those in the chorionic placenta were observed in the parenchymal cells of those organs, on the margins of necrotic areas. Pseudorabies virus was isolated from various organs of the aborted fetuses, but virus isolation from the placentas was not attempted. In a survey of 52 affected sows, sera from 49 (94.2%) neutralized the isolated virus. The findings indicated that the placental lesions caused by the virus were primary. The study also indicated the merit of routine examination of aborted fetal placentas and fetuses for diagnosis of pseudorabies.

Animals↗
PubMed1979

Experimental swine vesicular disease, pathology and immunofluorescence studies.

Two day old piglets were inoculated intravenously with 1 ml of swine vesicular disease virus UK-G 27-72 isolate. Using infectivity tests, immunofluorescent staining and gross and histopathological examination, pathogenesis of the infection was studied in tissue specimens collected daily from one through seven days postinoculation. Swine vesicular disease virus had a strong affinity for the epithelia of the tongue, snout, coronary band and lips, the myocardium and the lymphoid elements of the tonsil and the brain stem. The virus had the greatest affinity for the epithelium of the tongue. However, there was no evidence that the tongue was the initial replication site for swine vesicular disease virus. Prickle cells in the stratum spinosum appear to be the primary targets for the virus. The necrotic foci in the stratum spinosum appeared first, followed the next day by reticular degeneration and multilocular intraepidermal vesicular formation. In the digestive tract and most of the other visceral organs the short duration and sudden drop of the virus titres and the negative fluorescence and pathological findings suggest that these are not important sites for the replication of swine vesicular disease virus in this experiment. The virus was recovered from most of the central nervous tissue specimens. Although the piglets had significant central nervous system lesions, signs of impaired central nervous system function were not detected. However, subtle nervous signs could have been obscured by difficulties in locomotion resulting from severe lesions of the feet.

Animals↗
PubMedDate not supplied

Epidemiological characteristics and financial costs of the 1997 foot-and-mouth disease epidemic in Taiwan.

Between March and July 1997, a devastating outbreak of foot-and-mouth disease (FMD), serotype O, occurred in pigs in Taiwan. A total of 6,147 pig farms with more than 4 million pigs were infected, and 37.7 per cent of the pigs in Taiwan either died (0.18 million pigs) or were killed (3.85 million pigs). The epidemic reached its peak during the fifth week after it was first recognised. During the eighth and ninth weeks, a two-dose blanket vaccination programme was instituted which led to a large reduction in new outbreaks. Except for two cities, the whole of Taiwan was declared an FMD-infected zone. During the four months in which new farm outbreaks occurred, 21.7 per cent of the pigs on infected farms showed clinical signs, and there was an overall mortality of 3.95 per cent. During the early stages of the epidemic, the incubation period was as short as 24 hours and the case fatality rates for suckling piglets reached 100 per cent. The financial cost of the epidemic was estimated at US$ 378.6 million, including indemnities, vaccines, carcase disposal plus environmental protection, miscellaneous expenses, and loss of market value. Owing to the ban on exports of pork to Japan, it is estimated that the total economic cost to Taiwan's pig industry will be about US$ 1.6 billion.

Animal Husbandry↗
PubMedDate not supplied

An improved system for quantifying AgNOR and PCNA in canine tumors.

BACKGROUND: Quantifying silver stained nucleolar organizer regions (AgNORs) and proliferation cell nuclear antigens (PCNA) are useful techniques to measure proliferative activity of tumor cells; however, the nonspecific deposition of stains and overlappings of AgNOR and PCNA counts between grades of tumors hamper their applications. MATERIALS AND METHODS: Fifty-two surgical specimens from dogs, including mast cell tumors, perianal gland tumors and hyperplasias, fibromas, fibrosarcomas, and normal tissues were studied. The 3 microns dewaxed sections of formalin-fixed tissues were stained to detect AgNORs by a modified inverted incubation technique in a newly developed silver staining device. Data were collected and analyzed using a high-resolution digital microscope camera and image analysis software. Sequential sections were also stained for PCNA using an immunohistochemical method. RESULTS: The improved system for quantifying AgNOR provided more accurate and non-overlapping mean AgNOR counts, which enable us to distinguish benign states from malignant changes. The mean AgNOR cut-off points that discriminated grade II or III mast cell tumors from grade I, perianal gland carcinomas from adenomas (or hyperplasia), fibrosarcomas from non-fibrosarcoma tissues, were 6.0, 14.1, 9.4, and 8.8 respectively. The mean AgNOR areas, relative AgNOR areas, and PCNA positive rates of some malignant and non-malignant tissues (benign tumor and normal tissues) were significantly different (P < 0.05). CONCLUSIONS: This improved system is a sensitive and rather precise method for quantifying the AgNOR and PCNA. It provides a valuable objective measurement for differentiating benign and malignant tumors.

Anal Gland Neoplasms↗
PubMedDate not supplied

Proliferation characteristics of canine transmissible venereal tumor.

Canine transmissible venereal tumor (CTVT) grows progressively (P-phase) in the host and then spontaneously regresses (R-phase). The mechanisms behind the transition from the P-to R-phases are not well understood. In this study, in order to determine the proliferation characteristics of CTVT, we evaluated telomerase activity and enumerated nuclear organizing regions (AgNOR) and proliferating cell nuclear antigen (PCNA). It was found that CTVT cells from the P-and R-phases were both positive for telomerase activity, although it was lower in the R-phase. Evaluations of telomerase activity should take into account the stage of mitosis. Although, in the majority of cases, telomerase activity can be used to differentiate between benign and malignant tumors in dogs, other factors or markers should also be used to obtain accurate diagnoses. The PCNA-positive rate and the number and area of AgNOR per cell increased much more in the P-phase than the R-phase. However, the AgNOR values were always higher. Thus, the AgNOR count can be used to distinguish the P-and R-phases of CTVT. In addition, mitotic figures were much higher in number in the P-phase as compared to the R-phase. We believe that, during spontaneous regression of CTVT cells, slow tumor cell proliferation must contribute to the decrease in tumor size. However, shortening of tumor cell telomeres is not directly involved in this process. Other factors, such as expression of MHC antigens on CTVT cells, humoral immunity, cytokines released by the inflammatory cells and, especially, tumor infiltrating lymphocytes may contribute to CTVT regression.

Animals↗