Biomedical subjects

W C Chung

Publications and source records attributed to W C Chung.

At least 19 recordsLinked to original sources

PubMed1999

Oncospheres of Taenia solium and T. saginata asiatica develop into metacestodes in normal and immunosuppressed mice.

Normal and immunosuppressed mice were infected with oncospheres of Taenia saginata asiatica and T. solium. Although normal ICR mice were not susceptible to these two parasites, cysticerci were recovered from the immunosuppressed ones following venous injection. For T. s. asiatica, immunosuppressed ICR mice had an infection rate of 12.5% and six cysticerci of this parasite were recovered from three males. After injection of T. solium oncospheres, a high infection rate of 57% was obtained and 23 cysticerci were collected from 13 male immunosuppressed ICR mice. The immunosuppressed C57 mice had the highest infection rate (100%) and cysticercus recovery rate (2.4%) for T. solium. The infection rate and cysticercus recovery rate in six normal C57 mice were 40% and 3% respectively. The immunosuppressed ICR, Balb/c and C3H mice were also susceptible to T. s. asiatica.

Animals↗

PubMed1999

Prevalence and treatment of Pediculus capitis infestation among aboriginal school children in northern Taiwan.

In the present study, pediculosis was investigated among a total of 2,725 children from 35 primary schools in Hsiulin District of Hualien County, Jenai District of Nantou County, Wulai District of Taipei County, Chienshih District of Hsinchu County, Fushing District of Taoyuan County, and Nanao District of Ilan County. The overall infestation rate was 12.8%. The rates by districts were 19.7%, 17.3%, 16.7%, 15.1%, 7.9%, and 3.0%, respectively. The pediculicides including Nix (permethrin 1%) 56 gm/tube, Para aerosol (bioallethrin 0.66%) 90 gm/tube, and Perioderm (malathion 1%) cream shampoo 40 gm/tube were used to treat the head louse infestation in 83, 91, and 103 children; the cure rates were 97.3%, 94.1%, and 93.4%, respectively. No significant differences were found in these rates. The reactions were slight and transitory. A total of 636 lice was collected from the hair using fine-toothed combs before treatment and from the used towels after treatment of children in Wulai, Chienshih, Hsiulin, and Jenai Districts. Each child was found infested with a mean of 7.7 lice. The mean intensity of infestation was highest in Jenai (9.3) and Chienshih (8.7) came next. Wulai (3.7) and Hsiulin (3.6) had lower intensities.

Animals↗

PubMed1999

Sexual development of Taenia solium in hamsters from rodent-derived cysticerci.

In order to determine whether Taenia solium can be maintained in the laboratory using rodents as definitive hosts, six nude rats, 20 immunosuppressed Mongolian gerbils and 20 immunosuppressed Syrian hamsters were each inoculated through a stomach tube with three cysticerci recovered from SCID mice. No adult worms of T. solium were found in the intestinal tract of any of these 46 rodents. In addition, five immunosuppressed Syrian hamsters were fed with the same number of cysticerci enclosed in rodent muscles from SCID mice. Two of these hamsters were found to be infected 40 days post-infection, each harbouring a sexually developed worm in the intestinal tract. Although no eggs were produced, prepatent infections may be possible if a longer time was allowed for worm development. Moreover, the maintenance of the life cycle of T. solium in the laboratory using the rodent model can be established.

Animals↗

PubMed1998

Seroprevalence of Toxoplasma gondii antibodies among Atayal aboriginal people and their hunting dogs in northeastern Taiwan.

Atayal aborigines, living at an altitude of 1,500-1,600 m in northeastern Taiwan, still hunt for wild animals with the help of hunting dogs. In this study, the latex agglutination test (LAT) was used to detect sera anti-toxoplasma antibodies in this community as a measure of their exposure to Toxoplasma gondii. The positive rates for sera anti-toxoplasma antibodies were 21.8% and 19.6%, respectively, in 422 Atayal and 51 hunting dogs tested. Neither of the positive rates were found to be significantly different between male (22.1%) and female Atayal (21.4%), or between humans (21.8%) and dogs (19.6%) (P > 0.05) when compared by the Chi-Squared test (chi 2-test). A significant difference was observed between the positive rates in adults (28.3%) and children (18.7%) (P < 0.05), and the age pattern of prevalence is consistent with an increasing duration of exposure to Toxoplasma gondii with age. The consumption of raw liver of wild animals or insufficiently cooked meat may be the major mode of transmission of toxoplasmosis in Atayal.

Adolescent↗

PubMed1998

Taenia saginata asiatica: epidemiology, infection, immunological and molecular studies.

The taeniasis in East Asia has a special epidemiological pattern: people eat meat and/or viscera of pigs and acquire infection of Taenia saginata-like tapeworms. However, cysticercosis is more often found in pigs than cattles. In order to elucidate the taxonomic status of this parasite, we have conducted extensive field surveys, experimental infections, and morphological as well as immunological studies since 1981. After obtaining sufficient information from our studies, we finally came to the conclusion that the T. saginata-like tapeworm in Asia is a new subspecies of T. saginata and was named as T. saginata asiatica. The classical T. saginata was renamed as T. saginata saginata. In this paper, we provide the history of T. s. asiatica in Asia.

Animals↗

PubMed1998

Survival of Taenia solium cysticerci in carcasses of pigs kept at 4 C.

In the present study, the survival of cysticerci of Taenia solium in carcasses of 1 Small-Ear-Miniature and 2 Landrace Small-Ear-Miniature pigs kept in a refrigerator at 4 C was determined. The viability of the cysticerci was determined by observing evagination and active movement of the scolex under a fluorescent light after digestion in pig bile. Although no viable cysticerci were found after day 30, 58.8% cysticerci survived between day 26 and day 30. Moreover, more than 80% of the cysticerci were viable between day 1 and day 25. These findings indicate that taeniasis solium can be transmitted through eating raw or undercooked pork or viscera of pigs following refrigeration at 4 C for less than 30 days.

Animals↗

PubMed1998

[Larval distribution in different organs of ICR strain mice infected with Toxocara canis].

In this study 80 ICR mice were infected per os with 260 embryonated Toxocara canis eggs each through a stomach tube. Ten mice were sacrificed at weekly intervals over an eight-week period. Internal organs including livers, lungs, hearts, spleens, kidneys, brains, and carcasses were pooled separately and T.canis larvae from each category treated with artificial digestive fluid were recovered and later collected by the Baermann technique. Larval distributions at a given week in different organs or in a given organ at different weeks were compared and analyzed. Results revealed that total larval recovery increased from week one (11.6%) to four(19.7%); thereafter it decreased gradually and dropped to 13.4% by week eight. Larval distribution in different organs varied with time. No larvae were recovered from the heart or spleen during the study period, except for a small number recovered from the spleen in the 4th and 5th weeks after infection. In general, the larvae were recovered mainly from the brain, carcass and liver. Larval recovery from the liver was high in the first two weeks (4.5% and 3.6%, respectively) and in week 4(5.6%). Recovery from the brain increased drastically in week 4(6.8%) and remained high. Recovery from the carcass increased with time. In the case of the lungs, a sharp peak was observed in week 3(4.8%), but recovery from the kidneys was low (0.7-1.6%). Our results indicated that the ICR strain mouse is also a suitable animal model for the study of toxocariasis in paratenic hosts.

Animals↗

PubMed1998

[Seroepidemiology of Toxoplasma gondii infection among dogs in Taipei, Taiwan].

Seroprevalence of toxoplasmosis in dogs was investigated in Taipei from July 1995 to June 1996 by the latex agglutination assay. A total of 289 serum samples were taken from stray and domestic dogs as well as from dogs in randomly selected animal hospitals and pet stores. The overall seroprevalence among all dogs was 24.6% (71/289). With regard to the source of the dogs, the seropositivity was 15.4% (10/65) for dogs in animal hospitals, 16.3% (7/43) for dogs in pet stores, 15.5% (11/71) for domestic dogs and 39.1% (43/110) for stray dogs. The seropositivity of stray dogs was significantly higher than that of the domestic dogs (P < 0.05). However, there was no significant difference among the randomly selected places or dog strains (P > 0.05).

Animals↗

PubMed1998

[Seroepidemiology of Toxoplasma gondii infection among Atayal aborigines and local animals in Nan-ao district, Ilan county and Jen-ai district, Nan-tou county, Taiwan].

In this study, latex agglutination test (LAT) was used to detect sera anti-toxoplasma antibodies of Atayal aborigines and local animals in Nan-ao district, Ilan county and Jen-ai district, Nan-tou county as a measure of exposure to the Toxoplasma gondii. Out of 422 Atayal aborigines and 64 different animals were tested in Nan-ao district and 82 Atayal children in Jen-ai district were also screened, the positive rates for sera anti-toxoplasma antibodies were 21.8%, 17.2% and 15.9%, respectively. In Nan-ao district, neither were the positive rates significantly different in males (22.1%) and females (21.4%), nor in humans (21.8%) and dogs (19.6%) (P > 0.05). The seroprevalence in adults (28.3%) was significantly higher than that in children (18.7%) (P < 0.05), and the highest seropositive rate (38.1%) was in the age group 50-59 years and the lowest (7.7%) was in the age group 1-9 years. In general, the age pattern of prevalence is consistent with increasing duration of exposure to Toxoplasma gondii with age. For animals, the seropositive rate in dogs (19.6%) was also significantly higher than that in wild rats (7.7%) (P < 0.05). No significant difference in seropositive rate of Atayal children was observed between Nan-ao and Jen-ai districts (P > 0.05).

Adolescent↗

PubMed1997

In vitro hatched oncospheres of Asian Taenia from Korea and Taiwan develop into cysticerci in the peritoneal cavity of female scid (severe combined immunodeficiency) mice.

In vitro hatched (but not activated) oncospheres of Asian Taenia obtained in Korea and Taiwan, prepared by the sodium hypochlorite method, rinsed with sterile PBS several times and adjusted to 5 x 10(4)/0.5 ml PBS, were injected intraperitoneally or subcutaneously into male or female scid mice of 3 different strains. When these scid mice were sacrificed 4 months later, the females harboured fully developed cysticerci either in the peritoneal cavity or under the back skin, whereas males did not. All cysticerci from the peritoneal cavity were easily recovered by rinsing the abdomen with PBS. Although most cysticerci recovered from pig liver usually become calcified within 1-2 months, in female scid mice they all increased in size and were viable. Intraperitoneal (i.p.) injection of in vitro hatched oncospheres is recommended for easier recovery of Asian Taenia metacestodes in laboratory animals.

Animals↗

PubMed1997

Human Taenia eggs develop into cysticerci in scid mice.

The intermediate hosts for Taenia saginata and T. solium are cattle and pigs (and humans for the latter), respectively. In vitro-hatched (but not activated) oncospheres of both Asian Taenia (T. saginata asiatica, a new subspecies of T. saginata or T. asiatica, a new species) and T. solium injected subcutaneously into the backs of mice with severe combined immunodeficiency (scid) developed into fully matured cysticerci. Five-month-old metacestodes of Asian Taenia had no hooklets and were bigger in size than those previously reported and similar to those of T. saginata. Their morphology suggested that the cysticerci were more advanced than those in the intermediate host animals. It is suggested that scid mice are valuable experimental animal models for studying human taeniid cestode infections.

Animals↗

PubMed1997

DNA damage distribution in the human brain as shown by in situ end labeling; area-specific differences in aging and Alzheimer disease in the absence of apoptotic morphology.

DNA damage has been proposed to underlie neuronal degeneration in aging and Alzheimer disease (AD). To determine the histological distribution of DNA damage, in situ end labeling (ISEL) was applied as a marker for DNA breaks on 4 differentially affected brain areas. Occipital cortex showed considerable variation between cortical layers and between patients. Temporal cortex displayed little ISEL-labeling in controls, and in AD, surprisingly. In the hippocampus, which is strongly affected in AD, many ISEL-positive nuclei and glialike cells were found in AD as compared with controls. The hypothalamic supraoptic and paraventricular nuclei showed little DNA-damage, whereas the nucleus basalis was often, but not always, labeled by ISEL. In contrast to others, no apoptotic morphology was observed, only necrotic morphology. Our results in relation to postmortem delay indicate that, area dependent, increased DNA vulnerability may occur in AD. Furthermore, the distribution of DNA damage in cortex differs from that of plaques and tangles, suggesting that these 3 phenomena are, in principle, independent. Whether the enhanced level of hippocampal DNA breaks in AD underlies, or rather is a consequence of, previous degenerative changes in this brain area remains to be established.

Adult↗

PubMed1997

Human babesiosis in Taiwan: asymptomatic infection with a Babesia microti-like organism in a Taiwanese woman.

An asymptomatic Babesia infection was confirmed by laboratory diagnoses. The intraerythrocytic protozoan (designed TW1) isolated from a 51-year-old Taiwanese woman appeared to be morphologically consistent with small-form piroplasm, and measurements indicated that it had a body size of 1.5 to 2.5 microm in diameter. The typical features of ring, binary, and tetrad forms were observed in Giemsa-stained thin blood smears. A persistent and low-grade parasitemia was established after hamster inoculation. Indirect immunofluorescent-antibody reactivities indicate that this strain (TW1) of Babesia was serologically related to, but not identical to, the Babesia species (B. microti) that infects rodents. Antibody titers in the patient's sera combined with the clinical symptoms suggested that the present case was a chronic and subclinical babesial infection. A neighborhood human serologic survey indicated that the infection may have been acquired accidentally from an infected rodent and localized within the same family. Indeed, rodents from areas around the neighborhood were trapped, and a high prevalence (83%) of babesial infection was observed. The possible vector responsible for the transmission remains to be identified.

Animals↗

PubMed1997

Vaccination trials against Taiwan Taenia eggs in pigs injected with frozen oncospheres of Taiwan Taenia, Korea Taenia, T. saginata or T. solium.

When Small-Ear-Miniature pigs subcutaneously injected once with frozen oncospheres of Taiwan Taenia, Korea Taenia, T. saginata or T. solium emulsified with Freund's complete adjuvant (1.6 x 10(4)/0.4 ml) were challenged orally with 1.6 x 10(4) viable eggs of Taiwan Taenia 41 days later, they all showed strong resistance compared with pigs vaccinated with T. solium. Most pigs (5/8) of the former 3 groups harboured no cysticerci. The number of cysticerci was 5.5 +/- 9.1 (mean +/- S.D.), whereas pigs of the T. solium group and control group harboured 160 +/- 30.1 and 661 +/- 637.2 cysticerci, respectively. All cysticerci recovered from vaccinated pigs and most cysticerci in control pigs were degenerated or calcified at 36-55 days after oral egg challenge. These results strongly suggest that oncospheres of Taiwan Taenia and Korea Taenia are very similar to T. saginata in their immunogenicity in pigs.

Animals↗

PubMed1997

Sociocultural factors and local customs related to taeniasis in east Asia.

Taeniasis is an important medical and economic problem in many countries in East Asia. According to our estimation, there is an annual loss of US$18,673,495, US$13,641,021, and US$2,425,500 due to taeniasis in the mountainous areas of Taiwan, Cheju Island of Korea, and Samosir Island of Indonesia, respectively. Although taeniasis and cysticercosis due to Taenia solium have been reported, T. saginata asiatica is the dominate species in part of the world, especially in the mountainous and remote areas where the inhabitants are fond of eating raw or undercooked meat and/or viscera of domestic or wild animals. Therefore, sociocultural factors and local customs are the determinants in the transmission of taeniasis. In this paper, local customs and sociocultural factors including local dishes, accidental infection during dish preparation, and treatment for anaemia of children in the countries of East Asia were reviewed.

Adolescent↗

PubMed1996

Experimental studies on the pathway for migration and the development of Taiwan Taenia in domestic pigs.

The pig is the most favorable experimental intermediate host of Taiwan Taenia. Cysticerci in infected pigs are located in the liver except for a few extrahepatic ones. The present study was designed to investigate the pathway of migration of the oncospheres of Taiwan Taenia in the pig. In the first group, each of 5 Small-Ear-Miniature (SEM) and one Landrace-Small-Ear-Miniature (L-SEM) pigs were injected with 5000 hatched oncospheres into the ear vein. Three SEM and one L-SEM pigs were found to harbor 88 degenerated or calcified cysticerci only in the liver 51-81 days after injection. In the second group, each of 3 L-SEM pigs were injected with 5000 hatched oncospheres into the jugular vein. One of the 3 pigs was found to have 5 cysticerci (2 mature and 3 degenerated or calcified) only in the liver at 89 days post-injection. In the third group, each of 4 SEM, three L-SEM, and 3 L-SEM pigs were injected with 10,000, 10,000, and 5000 hatched oncospheres, respectively, directly into the portal vein after surgical opening of the abdominal cavity. All 10 pigs were found to be infected with a total of 1088 cysticerci (44 mature and 1044 degenerated or calcified) only in the liver 23-62 days after injection. Although the sites of injection in these three groups were different, the liver was the only final location of the cysticerci. These findings give strong evidence that the oncospheres migrate to the liver through the venous circulation and develop in this organ.

Animals↗

PubMed1996

Ectopic locations of Taenia saginata asiatica cysticerci in the abdominal cavity of domestic pig and monkey.

Eleven Small-Ear-Miniature pigs, 1 Landrace Small-Ear-Miniature pig, and 1 monkey (Macaca cyclopis) were infected experimentally with eggs of Taenia saginata asiatica. They were found to harbor cysticerci on the liver surface, each with a thin, whitish fiber connecting to another location in the same lobe, or to other lobes of the liver; some were also connected individually to the diaphragm, abdominal muscles, and gall bladder with a short, thin fiber. Moreover, they also harbored extrahepatic cysticerci. Most of these were observed on the omentum and in the peritoneal cavity, except for some suspended individually in the abdominal cavity by a long, thin, whitish fiber. The origin of the extrahepatic cysticerci and whitish fibers is probably from the surface of the liver of the host.

Abdomen↗

PubMed1995

Detection of apoptosis in murine scrapie.

In order to determine whether apoptosis contributes to the neuronal loss in scrapie, in situ end labeling was applied on brains of mice showing clinical signs of the disease. Positively labeled, apoptotic neurons were observed in the cerebellum, cerebral cortex and hippocampus, areas known to show characteristic scrapie-related vacuolation, and were absent in the brains of control mice. We conclude that apoptosis plays a role in the neuronal loss that occurs in scrapie. The importance of apoptosis as a predominant cell death mechanism in scrapie, however, remains to be determined.

Animals↗