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Objectives: Cardiovascular disease is one of the main causes of death and morbidity in Korea. In this study, the prevalence and incidence of developing hypertension in a male-workers' cohort were investigated during 3-years follow-up with a view to find the risk factors that affected the development of hypertension., Methods: Among the 5,374 people who participated in a routine health check up, 3,852 people with normal blood pressure and who had no history of hypertension were prospectively followed up for 3 years. The classification of hypertension was based on the JNC7 report (the Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure). Life style factors and underlying diseases that were related to the risk factors of hypertension were collected by using a self-report questionnaires via the internet., Results: The prevalence of hypertension was 28.3% (1,520/5,374) at the first screening (2001). It was found that the incidence in 2004 of hypertension for the follow-up subjects (3,711) who had normal blood pressure in 2001 was 7.6 per 100 person-year. Multiple logistic regression analysis of the variables related to the risk factors of hypertension was carried out. The relative risks were 1.037 (95% CI=1.022-1.053) as the age increased 1 year and 1.039 (95% CI=1.023-1.055) as the body mass index increased 1 kg/m2. The relative risk for the prehypertensive group was 2.501(95% CI=1.986-3.149) compared to the normotensive group. These results showed that age, body mass index and the baseline blood pressure were significantly related to the incidence of hypertension., Conclusions: The incidence of hypertension was 7.6 per 100 person-year during follow-up. It was concluded that the risk factors for developing hypertension in the short-term were age, BMI, and prehypertension; Especially, this showed that it is necessary for prehypertensives to manage their body weight and blood pressure to prevent hypertension in middle-age by modifying their life style.

Prevalence of sparganum in the frog (Rana nigromaculata) was surveyed in Dae-jeon city and in suburbs of the city, Chungnam Do. 39 (3.9 %) out of 1,011 frogs were infected with the worm, and the highest prevalence rate of sparganum was found the frogs from Shintanjin area(11.3 %). Infection rates of sparganum were observed due to the body weight and sex of frogs. The highest infection rate of frogs, the body weight of 50 gms or more, showed 30.3 per cent(female: 41.7 %, male: none), on the other hand, no worm was found in young frogs(less than 10 gms). Distribution of sparganum in the frogs was recorded and 82.6 % of worms were distributed in the femoral intermuscular connective tissues of the hind legs. Among those infected frogs, number of worm burden was one to five worms, and 53.3 per cent of frogs were infected by only one worm.

The prevalences of the fluke belonging to genus Metagonimus have been reported along the upper stream of inhabitants by several workers since 1980, however the taxonomical problems of the fluke was not yet settled. The larval flukes; cercaria and metacercaria as well as their intermediate hosts, and adult were studied in order to identify the Metagonimus in the areas. The results obtained are summarized as follows: The snails, Semisulcospira globus were collected from the three different localities along the upper stream of the River. The cercariae were found from 125(7.2%) out of 1,730 snails by natural emerging method, and were identified into 5 species including Metagonimus sp. (3.7%), Pseudexorchis major(1.4%), Cercaria nipponensis (0.9), Cercaria incerta (0.6%) and Cercaria yoshidae(0.6%). Cercariae of Metagonimus species had four to five oral spines on its anterior of the first line. The cercariae of Metagonimus were experimentally exposed to goldfish. Infection rate was 22.9% out of 105 goldfish, and the encysted metacercariae were found in fins(86.7%) and on scales (13.7%) of the fishes, but not in their muscle, head or visceral organs. Seven species of fish were caught in the Daecheong reservoir and the upper stream. Infestations with metacercaria of Metagonimus were found 100% in Opsariichtys bidens and the parasitized numbers of the metacercariae were observed from 250 to 2,400 per fish. In the upper stream, Zacco temmincki, Z. platypus and Pseudogobio esocinus were infected 100% with the metacercaria, on the other hand, the fishes caught in the reservoir showed the lower infestation rates, and a few metacercariae found in the fishes Carassius carassius and Cyprinus carpio in the reservoir and the stream. The majority of metacercariae was detected only on the scales of fishes. In order to know the infectivity and the distribution patterns in the intestine of hosts, rats and dogs were infected with the metacercariae obtained from O. bidens and Z. platypus. In addition the metacercariae obtained from Z. temmincki, P. esocinus and goldfish were given to the rats. The recovery rates of the worms in the small intestine of dogs were higher (63.3-65.8%) than those of the rats (3.5-31.6%). The flukes were found mostly in the middle and the lower part of small tntestine of the rats and the dogs, but no worm was collected in the upper part of the intestine of rats. The size of adult flukes varied by the hosts. In the adult flukes, oral sucker was smaller than ventral sucker, and the right and left testes were located diagonally, the uterine tubules circled around the upper left testis. The average egg size was 29.1 x 17.7 micro-meter. According to the above results, the flukes belonging to genus Metagonimus distributed along the Geum River was concluded to be identical with Miyata type of M. yokogawai as that Saito had proposed.

The distribution, external morphology, radula, chromosome numbers of Planorbidae snails were studied. 1. The specimens were collected at four stations in Nonsangun, Kongjugun, and Daedukgun which are located around Geum river. Three genera and three species of Planorbidae, Hippeutis cantori, Segmentina hemisphaerula and Gyraulus convexiusculus, were collected. H. cantori was the most abundant species among the three species. G. convexiusculus was the least abundant one. Each species could be identified on the basis of its external characteristic, since the periphery of each species has a peculiar shape. H. cantori was the largest one among the three species. The radula formula of each species was very similar to other species. The size of radula was proportional to the size of shell. The radula formulae of H. cantori, S. hemisphaerula, and G. convexiusculus were 29:1:29, 23:l:23, and 16:1:16 respectively. The difference of radula formula could be found in the total numbers of laternal and marginal teeth. The haploid chromosome number of H. cantori was eighteen (n=18). S. hemisphaerula and G. convexiusculus were assumed to be same in their chromosome numbers (n=18).

This study was undertaken to elucidate the status of Metagonimus species infection and to demonstrate the first and the second intermediate hosts of the fluke at the several localities along the Gum river, Chungchung-nam Do, Korea from March 1979 to October 1980. The results are summarized as follows: 1. Total 790 stool specimens of inhabitants from 6 localities along Gum river were examined by the combination of cellophane thick smear technique and formalin-ether concentration technique. The positive rate of intestinal helminths was 80.3 %, and the egg positive rate of Metagonimus sp. was 21 % from a total of 790 specimens examined. In the age bracket of 20~49, the positive rates of Metagonimus sp. were 31.1~36.5 %, and the males (26.8 %) were infected three times higher than females (8.9 %). By the area of the river, Gumsan which is located upper stream showed the highest positive rate (40.5 %) of the fluke, whereas the rates decreased gradually toward upper part of river (Muju) or the descending lower area of the river. The most lower area of river (Gangkyeong and Nonsan), no positive Metagonimus infection case was found. 2. The infection rate of Clonorchis sinensis in 790 was 37.3 %, and the status of mixed infection of Metagonimus with C. sinensis was found 127 cases (76 %) out of 166 cases with Metagonimus infection. 3. The result of measurement of ova from 166 cases of Metagonimus infection, large ova were found in 41.1 %, small size ova in 31.9 % and the mixed type in 27.1 %, respectively. The adult worms were recovered from the 6 cases after treatment with niclosamide, and the measurements of the worms showed similar morphological characteristics of the Metagonimus yokogawai. 5. Twenty-two species in 5 families of fresh water fish were caught. Out of 22 species of fish, 18 species were found infected with metacercaria of Metagonimus. In order to observe the distribution of metacercariae in the body and the rate of infection of the individual host, a total of 94 Pseudogobio esocinus were examined. Total 84 (89.4 %) out of 94 fish were infected with the metacercariae and the rates of distribution of the metacercaria were observed in the following order: on scale; 93.4 %, in gill; 3.2 %, head part; 2.9 %, but a few metacercaria was found in muscle and visceral organs. 6. The development of the metacercariae which were isolated from the scale of Pseudogobio esocinus were experimentally traced in the albino rat host from one day to 30 days after infection. At the 6th day, several eggs were visible in the uterine tubule of the some worms, on the 10th day, worms became 326.0 x 208.0 micrometer in size, however the bodies of worms grew no more until the 30th day after infection. The oral sucker was larger in size than the ventral sucker during early stage of the worms, but the 7th day after infection, it reversed. The ventral sucker situated on the ventral right side of the body. Right side of testis laid somewhat toward, and uterus and vetellaria extended to the posterior margin of the right testis. 7. Snails(Koreanomelania nodifila var. ovulum) were collected in the river, Buri-Myeon, Gumsan-Gun, and found the natural emerging ophthalmo-pleurophocercus cercaria. From the above result, the prevalence of Metagonimus species infection showed relatively higher rates from the inhabitants along the middle to upper localities of the river. Even though no sweetfish was caught in the surveyed areas, Gum river basin is the one of the new endemic foci of metagonimiasis in Korea.

In Korea where night soil used as fertilizer for crops and vegetables they may be contaminated simultaneously with infective stage of ascaris, hookworm and other helminthes. In this circumstance, the ascaris eggs and hookworm larvae may adhere to certain kinds of leafy vegetables(Chyu, 1957) and may remain viable even after pickling in brine or in other substances (Han and Ko, 1952; Soh, 1960). It has been shown that Heliogen(Thitasut, 1961) will kill the parasite eggs and larvae, and Sodium nitrite (Kozai, 1960; Kim and Soh 1964) and Thiabendazole (Kutsmi, 1964 and 1965; Kim et al., 1966) also had ovicidal action. The present study has been planned to study the ovicidal and larvicidal actions of several chemicals in Korean pickle juice(Kimchi) and the results are summarized as follows: 1. Heliogen solution(iodine 100 ppm) did not destroy the ascaris and hookworm eggs within 30 minutes at the temperature of 15-30 degrees C, but the hookworm larvae were killed within 3 minutes under the same conditions. Sodium nitrite which was added to pickle juice at the rate of 0.1 % destroyed more than 90 % of ascaris fresh eggs within 10 days and the embryonated eggs were destroyed within 2 days. Hookworm eggs were destroyed within 3 days and larvae were killed within 7 hours. 3. Thiabendazole which was added to pickle juice at the rate of 0.1-0.025 % inhibited the infectivity of ascaris embryonated eggs within 24 hours and hookworm eggs were destroyed in the same concentrations of the reagent. 4. Hydrogen ion concentration of pickle juice which was mixed with Sodium nitrite (0.1 %) was not changed for 10 days. 5. 1.5 mg of Sodium nitrite or Thiabendazole produced no toxicity in kidney and intestine of mice but slight pathological changes in the liver of the same animal.

Ultrastructural studies on the integument of digenetic trematodes were investigated by several workers (Senft et al., 1961; Bjorkman and Thorsell, 1964; Burton, l966; Erasmus, l968; Morris and Threadgold, 1967, l968). Clonorchis sinensis is a common parasite of human beings in the Far East. But as far little has been written on ultrastructure of the integument of this parasite. This study was carried out systematically to elucidate the ultrastructure of the integument of adult C. sinensis, and the results are summarized as follows: 1)The integument of C. sinensis was organized in two parts; the epidermis and the muscular layer. 2)The apical surface and basal surface of the epidermis were covered with typical plasma membrane and irregularly invaginated from the surface. Plasma membrane at perisuckers was extremely folded and appeared as if the epidermis might be divided with the layer. 3)The syncytial epidermis contained mitochondria and numerous secretory bodies, and which was connected by cytoplasmic processes to nucleated epidermal cells lying in the parenchyma. 4)The mitochondriae, the secretory bodies, the granular endoplasmic reticulum, the Golgi bodies and the free ribosomes were present in the perinuclear cytoplasm of epidermal cells, but no organelle was observed in processes of epidermal cell except some secretory bodies. 5)The fibrous layer consists of argentophile fiber and collagenous fiber, in which the circular muscle bundles and longitudinal muscle bundles were embedded. Bundles of muscle fiber are well developed at the perisucker, and mitochondriae in this portion contain many cristae as compared with any other parts of C. sinensis.

A survey of intestinal parasites infection among Korean people has been carried out during July 1969 to December 1970. A total of 2,250 stool specimens (male 1,101, female 1,146) was collected from all the provinces and Seoul city in Korea. The specimens were examined routinely by direct fecal smear, zinc sulfate flotation and formalin-ether sedimentation techniques. The results are summarized as follows: 1. Of 2,250 specimens examined, l,803(80.l %) were positive for intestinal parasites. 2. The positive rates of intestinal helminths were 1,644(73.1 %) among 2,250; Ascaris lumbricoides 46.0 %, Trichocephalus trichiurus 46.8 percent, hookworm 6.8 %, Trichostrongylus orientalis 7.0 percent, Clonorchis sinensis 12.1 percent, Enterobius vermicularis 1.6 %, Hymenolepis nana 0.7 percent, Taenia species 0.3 %, Metagonimus yokogawai 0.04 percent, Fasciolidae 0.04 % and one case of lung fluke Paragonimu westermani. 3. The positive rstes of intestinal protozoa were 786(34.9 %); Entamoeba histolytica 6.4 %, Entamoeba coli 20.5 percent, Endolimax nana 10.0 %, Giardia lamblia 5.1 %, Trichomonas hominis 1.1 percent, Chilomastix mesnili 0.5 percent, Iodamoeba butschlii 0.6 percent, Enteromonas hominis 0.7 percent, Dientamoeba fragilis 0.1 % and one case of Isospora hominis. 4. Sexual distribution of helminths and protozoan infections showed higher rate in female than that of male, except C. sinensis, H. nana, Taenia species or G. lamblia. 5. Infections of T. trichiurus, hookworm, T. orientalis, C. sinensis, Taenia species, E. histolytica, E. coli and E. nana increased with age. Conversely, H. nana and G. lamblia infections were more predominent in younger ages.

From 1960 through 1965, 39 cases with epileptic seizure caused by the Cystricercus cellulosae were experienced at Kaejong Mental Hospital, Okku-Gun, Chollapukdo province. The present study was carried on at the area of Chollapukdo province where Cysticercus cellulosae cases were frequently reported. 1. 39 Cystricercus cellulosae cases(35 male and 4 female) with epileptic seizure visited Kaejong Mental Hospital. Okku-Gun, Chollapukdo during the years of 1960~1965 from various Gun(county): Okku-Gun 13, Kimje-Gun 7, and Soonchang-Gun 6. The high incidence was found at the age group of 20~49 years and the distribution of 214 subcutaneous nodules were as follows: Trunk 56.6 %, upper extremities 26.6 %, head and neck 9.3 %, lower extremities 7.5 %. 2. According to the address of above 39 cases, taenia infestation of the inhabitants in the area was examined by questionaire form. Plain rural area (Maryong-Ri, Okku-Gun); Among 803 persons interviewed, 4.0 percent or 32 complained the output of Taenia segments. The male group showed higher incidence (6.4 percent) than the female(1.5 percent). The highest incidence was observed at the age group of 30~39 years. Most of the inhabitants of the area had the eating habit of raw beef and pork. Mountainous rural area(Bok-Heung-Myun, Soonchang-Gun); Among 542 persons interviewed, 33 or 6.1 percent complained Taenia infection. The higher incidence was observed in the male group(8.7 percent) than in the female group(3.1 percent), and also at the age group of 20~49 years. They had eating habit of raw beef and pork. The species of adult worm were identified by morphological examination. Totally 36 adult worms(Taenia saginata 21, T. solium 15) were obtained from 26 cases, and it was experienced that 5 T. solium were eliminated from one person.

A single dose of Tetramisole, 2.5 mg/kg body weight, was given to the infected cases of intestinal parasites. The number of cases were: Ascaris lumbriocides 96, hookworm 16, Trichostrongylus orientalis 10, Trichocephalus trichiurus 114 and Clonorchis sinensis 19. No dietary restriction before and after the administration of Tetramisole was required. 1. In Ascaris infection the egg negative conversion rate and the egg reduction rate were 92.7 per cent and 99.5 per cent, respectively. 2. In Trichostrongylus orientalis infections, 9 out of 10 cases were resulted egg negative after the single dose of Tetramisole, and hookworm, 12 out of 16 administered showed egg negative. However, there were no appreciable effectiveness to the cases of Trichocephalus trichiurus and Clonorchis sinensis. 3. Mild and transient side effects were noted in 75 cases (54.5%) out of 140 cases. The main symptoms were dizziness (25.5%), anorexia (25.5%), abdominal pain (18.6%), diarrhea (16.6%), headache (15.2%), nausea (14.4%) and fever (11.0%). From the above results, it is anticipated that Tetramisole is an effective anthelminthic for elimination of Ascaris, Trichostrongylus and hookworm.

Authors experienced a case of human infection with Anisakis sp. in left tonsil. The case was 27 year Korean female who visited Department of Otolaryngology, Severance Hospital with the chief complaints of swollowing difficulty, and the sensation of a foreign body in the throat, on November 20th 1968. Physical examination of the oral cavity revealed that both palatin tonsil were chronically enlarged. A larval worm was found in crypt of the upper portion of the left palatin tonsil. Chief complaints of the patient was improved after removal of it by forceps. The greyish white living worm was fixed in lactophenol solution for morphological study. The worm measured 36 mm in length by 0.6 mm in width, 2.4 mm in esophageal length, 1.4 mm in ventricule, 0.1 mm in tail length, and 0.025 mm in caudal spine length, respectively and histological study was carried out from the serial section of the larva which was stained with hematoxylin eosin. Authors identified that the larva was Anisakis species.