Biomedical subjects

W C Chung

Publications and source records attributed to W C Chung.

At least 19 recordsLinked to original sources

PubMed2001

Direct determination of sinigrin in mustard seed without desulfatation by reversed-phase ion-pair liquid chromatography.

Reversed-phase ion-pair liquid chromatography has been investigated for directly analyzing sinigrin in mustard seed without desulfatation. After extraction by phosphate buffer (pH 7.0) from the grind-pastes of inactivated-myrosinase mustard seeds, sinigrin was first isolated through deproteinization and centrifugation, followed by filtration and injection into the chromatographic system. A reversed-phase C18 column was used to separate the sinigrin with an eluent of acetonitrile (ACN)-water (20:80) containing 0.02 M tetrabutylammonium (TBA) as the counter ion at pH 7.0. Detection was carried out with an UV detector operated at 227 nm. Factors affecting the chromatographic separation and quantitative determination, such as concentrations of TBA and ACN, and pH, were studied. The linear dynamic range is larger than three orders of magnitude and the detection limit is 0.045 mg/L. The RSD is around 3% and the recovery is 85% (3% RSD, n = 3).

Calibration↗

PubMed2001

Structural and functional sex differences in the human hypothalamus.

Sex differences in the brain may be the basis not only for sex differences in reproduction, gender identity (the feeling of being male or female), and sexual orientation (heterosexuality vs homosexuality), but also for the sex difference in prevalence of psychiatric and neurological diseases ( Swaab and Hofman, 1995 ). In this brief article we discuss a few examples of structural and functional sex differences in the human brain.

Aging↗

PubMed2001

Analysis of polymorphic regions of Plasmodium vivax Duffy binding protein of Korean isolates.

The present study was designed to investigate polymorphism in Duffy binding protein (DBP) gene of Plasmodium vivax isolates of Korea. Thirty samples were obtained from P. vivax patients in Yonchon-gun, Kyonggi-do in 1998. The PCR products of the samples were subjected to sequencing and hybridization analyses of the regions II and IV of P. vivax DBP gene. Two genotypes, SK-1 and SK-2, were identified on the basis of amino acid substitution and deletion. The genotype of 10 isolates was SK-1 and that of 20 isolates was SK-2. Most of the predicted amino acids in the region II of DBP gene were conserved between the Korean isolates and Belem strain except for 4-5 amino acid substitutions. In the region IV of DBP, a 6-bp insert that was shown in the Sal-1 allele type was found in SK-1, and a 27-bp insert that was shown in the Papua New Guinea allele type was found in SK-2. In conclusion, the present findings suggest that two genotypes of P. vivax coexist in the endemic area of Korea.

Amino Acid Sequence↗

PubMed2001

Analysis of polymorphic region of GAM-1 gene in Plasmodium vivax Korean isolates.

The identification, characterization and quantification of Plasmodium sp. genetic polymorphism are becoming increasingly important in the vaccine development. We investigated polymorphism of Plasmodium vivax GAM-1 (PvGAM-1) gene in 30 Korean isolates. The polymorphic region of the PvGAM-1 gene, corresponding to nt 3792-4029, was amplified using polymerase chain reaction (PCR) followed by sequencing. All of the P. vivax Korean isolates were one type of GAM-1 gene, which were identical to that of the Belem strain. It is suggested that PvGAM-1 could not be used as a genetic marker for identifying or classifying P. vivax Korean isolates. It revealed that the polymorphic pattern was acquired basically by duplication and modification or deletion event of a 33 bp-motif fragment ended by poly guanine (G) and that there were at least three complete and one partial 33 bp-motif sequences within the polymorphic region in the longest cases such as those of South Korean and Belem isolates. In addition, we clustered P. vivax isolates with parsimonious criteria on the basis of PvGAM-1 polymorphic patterns (insertion/deletion patterns).

Animals↗

PubMed2001

Parasitic infections among the aborigines in Taiwan with special emphasis on Taeniasis asiatica.

According to the results obtained by our laboratory and the Department of Parasitology, Taipei Medical College, from 1995 to 1998, the overall infection rate of enterobiasis was 16% (4-29%) among 4,426 primary school students at 64 schools in 13 mountainous districts of 10 counties, and the infection rate of head louse infestation was 12% (3-26%) among 5,121 students. A continuous series of field studies on epidemiology and chemotherapy of taeniasis asiatica have been conducted between 1971 and 1992 among 27,359 aborigines in 88 villages of 14 districts in 10 counties and 3,104 were found to be infected, giving an overall infection rate of 11%. Laboratory studies have been performed on the morphology, intermediate hosts, experimental infection, immunology and molecular biology. Moreover, development of Taiwan Taenia in one of 3 volunteers has been successfully demonstrated since 1988. Moreover, the domestic pig was identified as the intermediate host of Taiwan Taenia as in the classical T. saginata (Poland strain). Most of cysticerci were developed in or on the parenchyma of liver. The results indicated that Taiwan Taenia is different from classical T. saginata. It has been named as T. s. asiatica. Moreover, the classical T. saginata was renamed as T. s. saginata. This paper summarizes findings and reviews those reported by our laboratory. In addition, the clinical manifestations and eating habits of the aborigines are also discussed.

Child↗

PubMed2001

Experimental studies on small hooks preceding large hooks in the growth and development of Taenia solium metacestodes.

In the present study, we have determined the growth and development pattern of rostellar hooklets of Taenia solium cysticerci (Zhengzhou and Harbin strains) in three pigs (1 SEM and 2 L-SEM strains) 89-196 days post experimental infection. A total of 3,675 cysticerci were collected from 3 pigs, 3,007 (82%) of 3,675 cysticerci were evaginated by enzyme method. 439 (15%) evaginated cysticerci were carefully examined and measured after dehydration, staining, and mounting on microscopic slides. Among 439 cysticerci, 234 (53%) had pair rostellar hooks, 88 (20%) with unpair hooks, 60 (14%) only small (outer row) hooks, and 57 (13%) no hooks including 34 hooks were completely dropped and 23 no hooks developed. The number ranged from 10 to 17 pairs for pair hooks and 1 to 29 for unpair ones. The length and width of rostallar hooks on the scolex of cysticerci were usually larger in the pig with longer infection time. Moreover, cysticerci with pair and unpair rostellar hooks had only small hooks and no hooks were present on their scolices. However, cysticerci with only large (inner row) hooks were not found. These findings indicate that the growth and development of small hooks precedes that of the large hooks in the formation of the two-row pattern rostellar hook in Cysticercus cellulosae.

Animals↗

PubMed2001

Experimental studies on physiological and morphological aspects of Cysticercus cellulosae in pigs.

Three Small-Ear-Miniature, 3 Landrace-Small-Ear-Miniature, and one Douc-Yorkshire-Landrace pigs were inoculated orally with 100 000 eggs of Zhengzhou strain or 10 000 eggs of Harbin strain of Taenia solium. A total of 3739 cysticerci were recovered from 3 Small-Ear-Miniature and 3 Landrace-Small-Ear-Miniature pigs, giving an infection rate of 85.7% and a cysticercus recovery rate of 1.1%. The predilection sites of Cysticercus cellulosae in descending order were leg muscles, abdominal muscles, thoracic muscles, liver, head muscles, diaphragm, tongue, heart, trachea, and omentum/testes. Except 2 calcified cysticerci in the tongue, 2 in the heart, and 176 in the liver, the remaining cysticerci were all alive. The greatest number of cysticerci per 100 g of muscles or viscera was found in the head muscles, followed by the leg, diaphragm, heart, tongue, thoracic, abdominal, omentum, testes, and trachea. All cysticerci were evaginated in pig's bile after fluid was drawn out from cysticerci, whereas evagination occurred in only 83.2% of those without fluid drawing. In 364 evaginated cysticerci, the mean length and width of scolex, proglottid, and bladder, and diameter of rostellum and sucker were 826 x 747 microm, 5,370 x 1,734 microm, 2,885 x 3,002 microm, 155 microm, and 253 microm, respectively. In the protoscolex, the mean number of segments was 33. Each cysticercus had 2 rows of rostellar hooks on the scolex, and the mean length and width of inner and outer hooks were 151 x 18 microm and 117 x 14 microm, respectively. The number of paired hooks ranged from 10 to 18.

Animals↗

PubMed2001

Current status of imported parasitic infection among foreign workers in northern Taiwan (1999-2000).

In the present study, a simple, economic and practical technique was employed for stool examination. Of a total of 6,146 fecal samples from foreign workers in Northern Taiwan between 1999 and 2000 were examined, 615 were found to be positive for parasitic infection and the overall infection rate was 10%. Newly arriving foreign workers had a significantly higher infection rate (15%) than those who had worked in Taiwan for 6-12 months (8%). The foreign workers came from Indonesia, Philippines, Thailand, Malaysia, and Vietnam. Except for the small number of workers from Malaysia which was not included, the infection rate order by nationality was Vietnamese (21%) > Indonesian (13%) > Philippino (10%) > Thai (4%). The female examined workers were about 3-fold of males and their infection rate (11%) was also significantly higher than the males (5%). The order of rates by age was 20-30 years (11%) > 31-40 years (8%) > 41-50 years (5%). According to the species of parasites, 569 foreign workers were infected with 1 species (9%) > with 2 species (0.7%) > with 3 species (0.1%). Totally, 14 species (10 helminths including 1 plant nematode, Heterodera and 4 protozoa; hookworm might include 2 or 3 species, but counted as one species here) were found, of which 10 species were pathogenic (9 helminths and 1 protozoa) and 4 non-pathogenic. Foreign workers from Indonesia harbored 12 species of parasites > from the Philippines, 9 species > from Thailand, 8 species > from Vietnam, 7 species.

Adult↗

PubMed2001

Studies on abnormality of metacestodes and adult worms of Taenia solium and Taenia saginata asiatica in rodents and pigs.

Abnormalities are not uncommon in Taenia saginata and T. solium. After examining 328 mature proglottids from 2 adult worms from two experimentally infected hamsters, 13 (4.0%) were found to have no genital pore but with numerous testes and several vas efferents; 1 (0.3%) one genital pore with one reproductive system; 12 (3.7%) one on each side with two sets of reproductive system; 17 (5.2%) two on one side with 2 sets of reproductive system; 8 (2.4%) one on one side and two on the other side with 3 sets of reproductive system; 2 (0.6%) two on each side with 4 sets of reproductive system; 4 (1.2%) three on one side with 3 sets of reproductive system, and 4 one on one side and three on the other side with 4 sets of reproductive system. Nine evaginated abnormal cysticerci of T. s. asiatica from three experimentally infected SCID mice each had two protoscoleces and a big bladder. From two experimentally infected pigs, one abnormal cysticercus was observed to have two invaginated canals each in one end. Another one had a neck-band behind the scolex and a big bladder. This paper is not only the first report of abnormality of T. solium from hamster but also the first one of abnormal cysticerci of T. s. asiatica from pigs and mice.

Animals↗

PubMed2000

Apoptosis during sexual differentiation of the bed nucleus of the stria terminalis in the rat brain.

The bed nucleus of the stria terminalis (BST) in the rat forebrain differs between males and females. To test whether apoptosis may contribute to the development of sex differences in the BST, the incidence of apoptosis was determined in sham-treated males and sham-treated females sacrificed on postnatal days (PN) 2, 4, 6, 8, 10, and 12 (PN 1 being day of birth). More apoptotic nuclei were found in the principal nucleus of the BST (BSTpr) in females than in males, whereas the reverse was true for the lateral division of the BST (BSTl). Moreover, the volume of the BSTpr was larger in males than in females, whereas there was no sex difference in the volume of the BSTl. Our results also confirmed earlier reports indicating that the incidence of apoptosis in the central part of the medial preoptic nucleus (MPNc) is higher in females than in males. No sex difference in apoptosis was found in the ventromedial hypothalamus (VMH) and paraventricular nucleus (PVN). The volume of the MPNc and VMH was larger in males than in females, whereas the PVN volume did not differ between males and females. To test whether sex differences in neonatal levels of gonadal steroids may cause sex differences in the incidence of apoptosis in the BSTpr, the incidence of apoptosis was compared between castrated males and females that were treated with testosterone propionate or vehicle on the day of birth. In the BSTpr of gonadal steroid-treated animals, the incidence of apoptosis was lower when compared to animals treated with vehicle, which was also true for the MPNc. These results are consistent with the hypothesis that gonadal steroids contribute to the sexually dimorphic differentiation of the BST by controlling the incidence of apoptosis.

Age Factors↗

PubMed2000

Rodent model for long-term maintenance and development of the viable cysticerci of Taenia saginata asiatica.

Although oncospheres of Taenia saginata asiatica can develop into cysticerci in immunodeficiency, immunosuppressed, and normal mice, no detailed information on the development features of these cysticerci from SCID mice is available. In the present study, the tumor-like cyst was found in the subcutaneous tissues of each of 10 SCID mice after 38-244 days inoculation with 39,000 oncospheres of T. s. asiatica. These cysts weighed 2.0-9.6 gm and were 1.5-4.3 cm in diameter. The number of cysticerci were collected from these cysts ranged from 125 to 1,794 and the cysticercus recovery rate from 0.3% to 4.6%. All cysticerci were viable with a diameter of 1-6 mm and 9 abnormal ones each with 2 evaginated protoscoleces were also found. The mean length and width of scolex, protoscolex, and bladder were 477 x 558, 756 x 727, and 1,586 x 1,615 microns, respectively. The diameters of suckers and rostellum were 220 microns and 70 microns, respectively. All cysticerci had two rows of rostellar hooks. These findings suggest that the SCID mouse model can be employed as a tool for long-term maintenance of the biological materials for advanced studies of immunodiagnosis, vaccine development, and evaluation of cestocidal drugs which would be most benefit for the good health of the livestocks.

Animals↗

PubMed2000

Capillaria hepatica: a spurious case with a brief review.

A 12-year-old Bunun aboriginal school student in Sanmin District Kaohsiung County, Southern Taiwan, was found to have Capillaria hepatica eggs in the feces during a survey on intestinal parasitic infection in 1997. Moreover, this student was also infected with Trichuris trichiura and Ascaris lumbricoides. The C. hepatica eggs were light yellowish-brown in color, 54 (40-60) microns in length and 29 (25-35) microns in width with a 3 (3-4) microns thick shell and two colorless egg plugs 7 (5-9) x 6 (5-8) microns. This is the eighth case of human spurious C. hepatica infection in Taiwan. In addition to the reporting of this case, the genuine and spurious infections of C. hepatica in humans as well as its infection in rats around the world are briefly reviewed.

Adolescent↗

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↗