A series of experiments were carried out to obtain some informations on host resistance in mice infected with Toxocara canis. Approximately 210 male BLAB/c mice were used and given various doses of infective eggs. For the purpose. the mean percentages of eosinophils were counted. and recovery rates of larvae from the liver, lung, brain, carcass and other tissues were examined separately at various intervals according to the experimental schedules.

Experiment I: Mice in groups I-1 and I-2 were given a single dose of 30 eggs and 100 eggs, respectively. Eosinophils and larvae were examined daily for 6 days and weekly for 21 weeks. Experiment II : Mice in groups II-1 and II-2 were given 100 eggs weekly for 2 weeks and 50 eggs for 4 weeks from 1 week after an initial administration of 30 eggs. Eosinophils were counted weekly and larvae were examined at 3 weeks after the final administration, respectively. Experiment III : Mice in 6 groups from III-1 to III-6 were given a challenge dose of 100 eggs at 1. 2. 3. 5. 7, and 9 weeks after an initial administration of 30 eggs. Eosinophils were counted weekly for 3 weeks and larvae were examined at the 3rd week after the challenge infection, respectively.

The means of eosinophils in groups I-1 nd I-2 respectively were 6.4% and 8.2% at 6 hr. and reached a maximum peak of 16.8% and 21.6% at 2 weeks, and the means decreased rapidly for the next 6 weeks. then fell gradually. The superinfection and the challenge infection in Experments II and III caused quicker and more intense rises of the eosinophils.

The recovery rates of larvae in groups I-1 and I-2 respectively showed 3 peaks at 48 hr. 1 week and 3 weeks, then decreased gradually. At 48 hr. 88.2% and 93.5% of the larvae recovered and 38.0% and 40.8% of the total larvae given were found in the liver, then decreased gradually until none was found at the end of the experiment. On the contrary. in the brain and carcass, the larvae accuulated repidly through the 1st week and the rates persisted up to the 8th week without remarkable variation. The recovery rates of larvae in total, and from the brain and carcass in groups of Experiments II and III decreased remarkably, whereas those from the liver increased significantly compared with groups I-1 and I-2 at the corresponding weeks of examination.

Transition patterns of the means of eosinophils in groups of Experiments I and II and those of total recovery rates of larvae in groups of Experiment I were essentially similar each other in rise and fall throughout the experiments.

From the overall results, it is strongly suggested that eosinophils do affect the development of resistance to invading Toxocara larvae, and the higher recovery rates of larvae in the liver indicates that the liver is the organ which may play a role of protection against infection with T. canis larvae by means of immunomechanism in mice.

The present study was carried out to evaluate the efficacy of the experimentally prepared injection of nitroxynil-levamisole against liver fluke and gastrointestinal roundworms in goats and cattle. For the purpose, the dose confirmation trial, the dose reduction trial and clinical field trial were conducted according to "the guidelines for evaluating the efficacy of anthelmintics in ruminants" approved by the General Meeting of the 9th International Conference of the World Association for the Advancement of Veterin ary Parasitology" in 1981.

The results obtained are summarized as follows ;

1) A single dose of 10mg/kg of nitroxynil injection alone against the liver fluke and that of 5.0mg/kg of levamisole injection alone against gastrointestinal roundworms in goats were highly effective in the cure rate and the egg reduction rate, respectively.

2) A single dose of the experimentally prepared compound injection at the dose levels of nitroxynil 10.0mg-12.0mg/kg and levamisole 5.0mg-6.0mg/kg was highly effective in the egg reduction rates of both liver fluke(98.4%-100%) and gastrointestinal roundworms(97.3%-98.4%) without any side reaction in goats.

3) A single does of the experimentally prepared compound injection at the reduced dose level of nitroxynil 7.5mg/kg and levamisole 5.0mg/kg was highly effective in the egg reduction rates of both liver fluke and gastrointestinal roundworms in goats.

4) In the clinical field trial, a single dose of the experimentally prepared compound injection at the reduced dose level of nitroxynil 7.5mg/kg and levamisole 5.0mg/kg showed also very high efficacy in the cure rates and the egg reduction rates of both liver fluke and gastrointestinal roundworms in Korean cattle, dairy cow and beef cattle. However, it was not effective against Ostertagia sp. among gastrointestinal roundworms. No side reactions were noted.

The present study was carried out to examine the effect of a carcinogen, aflatoxin B₁ on the pathogenesis of the bile duct changes in mice experimentally infected with Clonorchis sinensis metacercariae. A total of 75 male albino mice of the BALB/c strain was used, and divided into 3 group; group I, treated with 1.0ppm aflatoxin B₁ in drinking water alone for 12 weeks; group II, given 50 Clonorchis sinensis metacercariae alone and group III, given 50 metacercariae at the beginning of the 12 week treatment with 1.0 ppm aflatoxin B₁ in drinking water. Three mice were served as untreated-uninfected normal control. All mice were fed the standard protein diet which was synthesized and supplied by the Laborarory of Sam-Lip Food Co. Since the 4th week three mice from each group were removed and sacrigiced at 4 week interval up to the 32nd week. The hepatobiliary tissues were extracted and subsequently prepared for light microscopic examination. The tissue specimens were stained with hematoxylin and eosin. Mice in group I showed no significant changes except the lower degrees of bile ductular proliferation and inflammatory cell infiltration at the portal regions at an earlier stage. In groups II and III there were remarkable together with extensive acute and chronic inflammatory cell infiltrations, cellular atypia and periductal fibrosis from earlier stages. However, in group III the histopathological changes observed were more prominent than those in group II throughout the observation. As the time elapsed, they showed gradual regression with some fluctuations in the degrees. No any evidences of malignant changes of epithelial cells were noted in group II, but in group III the first tumor was found at the 28th week and the second one was at the 32nd week, respectively. Histologically the tumors observed were well differentiated adenocarcinoma of the bile duct. It was appeared that the tumors were of peripheral origin with a tendency of multifocal growth. They also showed an infiltrative growth pattern, increased mucin droplets, increased nuclear-cytoplasmic ratio and nuclear hyperchromatism. No hepatocellular carcinoma was noticed throughout the observation. In conclusion, it was suggested that Clonorchis sinensis infection promotes carcinogenic action aflatoxin B₁, a carcinogenic agent.

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• Effect of Clonorchis sinensis infection and dimethylnitrosamine administration on the induction of cholangiocarcinoma in Syrian golden hamsters
  J H Lee, H J Rim, U B Bak
  The Korean Journal of Parasitology.1993; 31(1): 21.     CrossRef

The main objective of the present study was to obtain further information on the histopathologic changes in the bile ducts at chronic stage of Clonorchis sinensis infection for the establishment of relationship between clonorchiasis and cholangiocarcinoma. BALB/C male mice were used. Approximately 500 metacercariae were given orally to each mouse. Three mice were sacrificed once monthly from the 10th month through the 20th month after infection. The hepatobiliary tissues were fixed in 10% formalin solution, sectioned serially, and stained with hematoxylin and eosin for histopat-hologic examination. The results obtained are summarized as follows; 1) The bile ducts showed moderate adenomatousproliferation, mucinous cell metaplasia and goblet cell metaplasia from the 10th month up to the 13th month after infection, then gradual regression. As time elapsed, scattered abortive acini were aslo regressive. 2) Most of the stromal fibrous tissues were replaced by excessive collagen fibers which persisted throughout the observation. The pictures were considered to be irreversible. 3) Polymorphonuclear leucocyte and eosinophil infiltrations was slight in the degree, while chronic mononuclear leucocyte infiltration was moderate throughout the observation. 4) Even though no any evidence of malignant change of epithelial cells was demonstrated thoughout the observation, Clonorchis infection was considered to be an impotant predisposing factor in carcinogenesis in the bile ducts.

The objective of this sutdy was to obtain further information on the relationship between oncogenesis of cholangiocellular carcinoma of the liver and the infection with a liver fluke, Clonorchis sinensis in the earlier stage of the infection. A group of 24 BALB/C male mice were used. Approximately 500 metacercariae were given orally to each mouse. Three mice were killed on the scheduled day, 3rd, 5th, 7th, 10th, 15th, 20th, 25th and 28th day after infection, respectively and histopathologic changes of the bile ducts were examined using hematoxylin and eosin stain method. The histopathologic findings observed were summarized as follows ; 1) Mice killed on the 3rd day showed a mild epithelial hyperplasia with the formation of papillae and adenomatous tissue proliferation. Bile ducts were dilated and the stroma was infiltrated by inflammatory cells, mainly eosinophils and polymorphonuclear leucocytes. Occasionally mitotic figures and atypia of epithelial cells were seen. Worms were found in the distal peripheral smaller branches of the bile duct. 2) Mice killed on the 7th day gave a mild connective tissue proliferation in addition to more striking pictures in the bile ducts. Chronic mononuclear leucocytes appeared in the stroma. 3) Bile duct chagnges including epithelial hyperplasia, adenomatous tissue formation, connective tissue proliferation and inflammatory cell infiltration were greater in the degrees in mice killed on the 10th day after infection. Mucinous cell metaplasia and collagen fiber proliferation were also observed. 4) From the 15th day throughout the 28th day after infection, mice showed the most striking pictures of peithelial hyperplasia, adenomatous tissue formation and mucinous cell metaplasia. The stroma demonstrated the excessive eosinophil and chronic mononuclear leucocyte infiltrations, while polymorphonuclear leucocytes were decreased.

The present study carried out to obtain further information on the relationship between primary carcinoma of the liver and infection with a liver-fluke, Clonorchis sinensis. A group of 50 male albino mice were used. Approximately 500 metacercariae were given orally to each mouse. Maturity of worms was followed up by fecal examination. Distribution of worms in the hepatobility system was also checked by using 5 egg positive mice at the end of the 1st month of infection. For histopathological examination, 4-5 mice were sacrificed monthly through the 9th month of infection. The liver tissues including common bile duct and the gall bladder were fixed in 10% formalin, sectioned serially, and stained with hematoxylin and eosin. The results obtained are summarized as follows; 1. The initial day of egg output was the 28th day in average ranging from 22nd to 33rd day of infection. 2. Recovery rate of worms was revealed as low as 16.8%, and of which 64.5% was found in the intrahepatic ducts, 33.2% in common bile duct and 2.3% in the gall bladder. 3. Parasites were found in the intrahepatic ducts throughout the observation. 4. At the end of the 1st month of infection, epithelial cells of bile ducts showed varying degrees of hyperplasia and desquamation, marked adenomatous tissue proliferation, enormous acini formation with remarkable mucinous cell metaplasia and definite atypia. Stratification was scanty. Periductal and portal spaces demonstrated the extensive chronic mononuclear leucocytes and the moderate fibrosis. Similar pictures persisted up to the 4th month of infection. 5. After the 5th month, all of the outstanding features of epithelial cells showed gradual regression. On the other hand, the most striking picture in this period was the great increase of collagen fibers in periductal and portal spaces. Although tumors were not found in the present study, overall results obtained were strongly suggestive to make an inference that clonorchiasis is responsible for the neoplastic transformation of epithelial cells of intrahepatic bile ducts in experimentally infected albino mice.

The present study was undertaken to get further information on the migratory gehavior of Toxocara canis larvae in the central nervous system in eperimentally infected mice. Mice were infected with approximately 500 of infective eggs of T.canins. According to the schedule, mice, 5 males and 5 females, were sacrificed at 2,3,5,7,14,21,28 and 56 days after injection and the brain tissue was extracted from each mouse and devided into six parts ; cerebrum, cerebellum, medulla oblongata, olfactory bulb, potuitary and spinal cord. Number of the larvae was counted qualitatively and quantitatively. The results are summarized as follows : 1. Total recovery rate(in average) of the larvae in the brain at the various intervals gradually inceased from 0.4% to 10.6% with the highest rate on the 28th day of post-infection. 2. Total recoery rates(in average) of the larvae obtained throughout the study were 54.2% in male and 45.8% in female, out of 504 larvae. 3. Distribution rates of the larvae were revealed as high as 57.5% in cerebrum and 32.5% in cerebellum, and 4.4% in medulla oblongata, 2.8% in spinal cord, 2.0% in olfactory bulb and 1.6% in pituitary in decreasing order. 4. Number of the larvae per mg of wet weight of the brain found was 0.06 in cerebrum and cerebellum, 0.03 in olfactory bulb and pituitary, 0.02 in medulla oblongata and 0.01 in spinal cord, respectively.

The objective of this paper is to test the reinfectivity of Toxocara canis larvae in mice that are fed with rat's liver tissue containing larvae in granuloma formed by administration of infective eggs of dog ascarid. A serial experiment was carried out with 10 non-pregnant mice to observe the pattern of granuloma formation and with 10 pregnant mice to establish the intrauterine and the intramammary migrations. Digestion method using Baermann apparatus and histological examination of the tissues of the tissues were applied as required. The results are summarized as follows: 1) Typical granulomas were formed in the liver of white rats. 2) In mice fed with liver tissue of white rats, granulomas were formed more or less rapidly and necrotic change was observed in the center of the granuloma. 3) Some larvae were recovered from the uterus and placenta at the 15th day of pregnancy, but not in the fetus. 4) A few larvae were deteced in mammary gland at the first day after parturition. However, larva disappeared from the unterus after parturition.

An epidemiological study on the primary carcinoma of the liver was carried out to obtain further information on the causal factor of cholangiocarcinoma and hepatocellular carcinoma during the period of 1997 and 1978. Total 102 hospital records of the primary carcinoma of the liver from 3 Hospitals were collected and analysed. Among 102 primary carcinomas of the liver, cases of hepatocellular carcinoma and cholangiocarcinoma were 96 (M83, F13) and 6 (M6, F1) respectively and the ratio was 16.0 : 1. Total cases of the primary carcinoma of the liver combined with clonorchiasis were 18 (M16, F2). Prevalence rate was 17.6 Clonorchiasis cases combined with hepatocllular carcinoma and cholangiocarcinoma were 14 (M13, F1) and 4 (M3, F1). Prevalence rate (66.7%) in cholangiocarcinoma was much higher than that (14.6%) in hepatocellular carcinoma. The relative risk was 11.8. Average ages of total cases, hepatocellular carcinoma and cholangiocarcinoma cases were 51.9, 51.5 and 58.5 respectively. Ages of clonorchiasis cases combined with hepatocellular carcinoma were distributed from 30 throughout 60 and those combined with cholangiocarcinoma were limited in 50 and 60. From the epidemiological point of view, the evidence for a carcinogenic effect of Clonorchis infection is strongly suggestive.

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• Enhancement of dimethylnitrosamine-induced glutathione S-transferase P-positive hepatic foci by Clonorchis sinensis infestation in F344 rats
  J.J. Jang, K.J. Cho, N.H. Myong, J.Y. Chai
  Cancer Letters.1990; 52(2): 133.     CrossRef

The genus Onchocerca has received much attention due to the medical and veterinary importance of certain species within the genus. Recently, additional interest on onchocerciasis of domestic animals has been stimulated by the report of human infections with Onchocerca of animal origin.

In Korea, so-called worm nodules have been encountered in cattles slaughtered at abattoirs. From this reason, it is considered to be very important to carry-out epizootiologic studies on onchocerciasis in Korean cattle and other domestic animals.

The present work was designed to investigate the incidence and morphology of microfilariae of Onchocerca sp. in Korean cattle.

For study, skin tissues on the umbilical region of cattles were taken and sliced into small pieces, and kept in saline for 2 hours. Microfilariae were collected and fixed in pure alcohol and in 2% formalin solution, and stained with Giemsa stain solution respectively.

The results are summarized as follows;

1) Microfilariae were found in 49 (24.5%) among total 200 cattles examined.

2) Average length and width of microfilariae were 249.7µ × 3.6µ in pure alcohol fixed specimen and 248.8µ × 3.9µ in 2% formalin fixed specimen, respectively.

3) Distances of each significant structure from the anterior end of head of microfilariae reveales; BNC 6.5µ(4.5~8.2µ), AMNR 59.2µ(53.8~67.3µ), PMNR 62.3µ(58.2~69.9µ), EP 86.8µ(82.4~94.1µ), EC 96.6µ(86.9~103.5µ), G₁ 178.3µ(162.2~192.8µ), AP 221.0µ(189.5~237.5µ) and ENC 240.4µ(226.2~258.9µ).

4) Four G cells and 3 or 4 small rod shaped caudal nuclei proceeded to a bar shaped terminal nucleus were observed.

From the characteristics of body length, clear portion of the head and caudal nuclei and general apperance expressed with a percentage of the distance from the anterior end to body length the microfilariae examined in the present study can be identified as O. gibsoni.

Recently, attention became more sharply focused on zoonotic larval nematode infections, particularly infections due to dog hookworm, Ancylostoma caninum and dog ascarid, Toxocara canis. In general, it has been known well that malnutrition and a protein free diet resulted in the increased susceptibility and the decreased acquired resistance to parasite. However, there was no report concerning the nutritional condition of the host and infectivity of a certain nematode larva. In ordet to elucidate the effect of protein in the diet on the larval migration in the organs and tissues of mice and on the fraction of gamma-globulin related closely with antibody response, an experiment was designed to follow the short-term course of infection of Ancylostoma caninum larva in mice fed with a standard diet(group 1), protein-free diet(group 2) and high protein diet(group 3). For the purpose, tissue digestion method using Baermann apparatus for the larval count and Gelman electrophoresis equipment for the measurement of gamma-globulin were applied. The results obtained from the present study are summarized as follows: 1) The range of average recovery rates of larva throughout the observation was 7~49% in group 1, 11~56% in group 2 and 6~44% in group 3, respectively. Significantly more larvae were detected and the larval migration preceeded more rapidly in group 2. 2) All the levels of total serum protein decreased soon after infection and the patterns continued up to the end of the experiment. It indicated that the compensatory power of the host was not able to maintain constant protein concentration. 3) The range of gamma-globulin fraction of serum protein after infection revealed 16.3~18.8%, a moderate increase in group 1, 17.5~19.3%, a pronounced increase in group 3, and 13.5~14.2%, a low degree of increase in group 2, respectively. Increase of gamma-globulin in group 1 and 3 were highly significant statistically to compare with that of group 2.