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Biomedical subjects

F H Tai

Publications and source records attributed to F H Tai.

At least 19 recordsLinked to original sources
PubMed1983

[Temperature-sensitive mutant of influenza virus: isolation and evaluation in mice].

A provisional temperature-sensitive mutant, ProTs8, of influenza A/WSN (H0N1) virus was isolated from primary chicken embryo fibroblast culture inoculated with influenza A/WSN (H0N1) and incubated with medium 199, containing 2% chicken embryo extract, and 400 micrograms/ml of 5-fluorouracil. Its EOP (efficiency of plaquing) value between 39.5 degrees C and 33 degrees C was about 0.007, and the control was about 0.82. Through lowering the shut-off-temperature to 38 degrees C, we had successfully isolated two temperature-sensitive mutants, Ts8-38 and Ts8-37, from their parent, ProTs8. 50% mouse virulent doses (MVD50) of these two mutants were around 10(-0.6), while the control group was 10(-4.0). Groups of mice immunized with 0.4 MVD50 or 0.04 MVD50 of Ts8-38 or Ts8-37 mutant by nasal instillation had shown significant resistance to the challenging infection of the wild type virus, influenza A/WSN (H0N1) (challenge dose, 1,000 MVD50 or 100 MVD50), if compared to the control group.

Animals↗
PubMed1982

Effects of type A botulinus toxin on primary chick embryo cell culture.

Type A botulinus toxin was studied for its ability to inhibit the DNA, RNA, and protein synthesis of a chick embryo primary cell culture. 3H-thymidine, 3H-uridine, and 14C-leucine were employed as tracers for measuring the synthesis of DNA, RNA, and protein, respectively. In the presence of large doses (2 x 10(6) MLD/ml) of type A botulinus toxin, RNA synthesis was inhibited to a lesser extent than DNA synthesis, and a very weak inhibition of protein synthesis was observed. The effect of type A botulinus toxin on DNA synthesis of a chick embryo brain cell suspension culture was also tested. The DNA synthesis of the brain cells was strongly inhibited by this toxin.

Animals↗
PubMed1982

Fecal Salmonella carriers in the Chinese army recruits in Taiwan.

A survey for Salmonella carriers in the Chinese army recruits was made. Each isolated strain was identified by conventional biochemical tests, rapid Inolex plates, and for identification serological methods. The rapid Inolex plates could save approximately 24-48 hours for identification. Salmonella was detected in 1.83% of the rectal swabs collected from 1,150 recruits and 50 cooks. Among the 22 isolates 5, 1, 5, and 6 strains were identified as Salmonella groups: B, C1, D and E1 respectively and 5 strains were ungroupable. Salmonella isolates were found to be susceptible to chloramphenicol, kanamycin, ampicillin and tetracycline. Chloramphenicol or kanamycin is still the drug of choice for treatment of Salmonella infections, but the former should be used with caution.

Adult↗
PubMed1979

[Studies on staphylococcal enterotoxin B. III. Purification with absorbents].

The biological and immunological activities of Staphylococcal enterotoxin B are stable in pH 2.0 approximately 11.0, and also resistant to proteolytic enzyme (trypsin, pepsin) digestion for 3 approximate 4 hours. Therefore, the toxin could be purified with trypsin digest and then absorbed on kaolin and Kieselgel, followed by eluting the different pH buffer solutions. Further purifications was chromatographied on CM-Sephadex column.

Absorption↗
PubMed1978

[Studies on staphylococcal enterotoxin B. 1. Quantitative assay by capillary tube single diffusion test (author's transl)].

A method for rapidly identifying and quantitating small amount of staphylococcal enterotoxin B was developed on capillary tube single diffusion test. The high sensitivity of method has the advantages to save antiserum and incubation period. Some factors such as concentration of antigen and antiserum, incubation temperature, buffer systems, and position of capillary tube all might affect the test accuracy. If all those affecting factors were concerned, the toxin would probably be standardized. The most accessible quantitative estimation was accomplished by means of (1) plotting a precipitation curve from the different concentrations of standardized staphylococcal enterotoxin B; (2) the sample to be test was diluted by serial two-fold method with the same buffer system; (3) select suitable 3--5 dilutions to perform capillary tube diffusion test, taking the values of precipitation bands as abcissa and sample dilutions as longitudinal axis, rendered the precipitation curve of sample exquisitely paralled to that of the standard; (4) calibrate the figure values of sample exactly on the precipitation curve, and reading the toxin content of specimen to be tested from standard curve.

Enterotoxins↗
PubMed1978

[Studies on staphylococcal enterotoxin B. II. Production and regulation (author's transl)].

Enterotoxigenic strain of Staphylococcus aureus (ATCC 14458) was grown under various conditions with constant shaking to determine the requirements for maximum toxin production. It was evident that 3% tryptic soy broth, 3% NZ-Amine NAK + 3% casein hydrolysate, 3% NZ-Amine NAK + 1% yeast extract, and 3% NZ-Amine NAK + 1% yeast extract + 0.2% glucose are most available toxin production media. But concentration of glucose could strictly triggered the enterotoxin producing efficiency. When glucose concentration was less than 0.5%, although with higher yield, the toxin production was delayed for certain period of time. However, if glucose concentration was up to more than 0.5%, the enterotoxin production was almost inhibited. Some metabolites of glucose to elucidate the inhibitory effect have also investigated. Our results indicated that glycerol and citric acid inhibited the toxin production directly, while the inhibitory effect of lactic acid and acetic acid were due to those acidic metabolites, decreased the pH value of media, and adversely suppressed the bacterial growth.

Culture Media↗
PubMed1977

Pyocyanine production by Pseudomonas aeruginosa.

Dextrose enhanced the growth of P. aeruginosa but suppressed the biosynthesis of pyocyanine. The preformed pigment could be released from dead cells. Pigmentation was not correlated directly with number of viable organisms in the culture. High concentration of maltose likewise inhibited pyocyanine production. Maltose contained in medium used for pyocyanine production by P. aeruginosa should be kept in low concentration or omitted.

Culture Media↗
PubMed1976

Mycoplasmal pneumonia in Chinese veterans.

From 1967-1973, a total of 54 strains of Mycoplasma pneumoniae was isolated from patients suffering from different acute respiratory diseases, with an average positive isolation rate of 4.7%. Most mycoplasmas were isolated from patients aged 40-60, and with pneumonia of primary atypical pneumonias. The highest frequency of isolation was found in sputum collected 4-8 days after onset of illness. Colony formation on PPLO medium usually occurred 7-12 days after incubation. Serological tests were methods of choice for diagnosis of mycoplasmal pneumonia. In the 6 years period, 163 patients were diagnosed: 74 were positive only by metabolic inhibition test (MIT), 55 were positive only by cold agglutination test (CAT), and 34 gave positive by both tests. Of the above 2 tests, the CAT is nonspecific, but the MIT appears to be more sensitive and specific. Of the 94 sera positive by MIT, 42 (48.2%) were also positive by CAT; of those negative by MIT, 45 of 507 (8.8%) were positive by CAT. Of 45 sera with positive mycoplasma isolation, 37 (82.2%) were also positive by MIT, but only 22 (48.9%) showed the rises of CAT titers. Clinical features of mycoplasmal pneumonia were almost similar to those described by the other investigators. The chief symptoms were fever, coughs, chills, rales, malaise, sore throat headache and chest pain. The sedimentation rate of erythrocytes was accelerated. White count was normal in most cases. Both leucocytosis and leucopenia were found in 10% of the cases. Seasonal variation in incidence of mycoplasmal pneumonia was not obvious, however the lowest incidence occurred during summer. A roentgenogram of the chest was necessary for diagnosis of mycoplasmal pneumonia, and the lung infiltration was mainly located on right side (57.1%), segmentally, and limited to one lobe, especially the lower lobe.

Adult↗
PubMed1976

Reovirus antibodies among animals in Taiwan.

Serum specimens for reovirus antibody survey were collected from 60 pigs, 50 buffalos, 30 rabbits, 30 guinea pigs, 20 albino rats, 60 Swiss mice, 15 Taiwan monkeys, 14 goats and 12 dogs. Serum antibodies were measured by the hemagglutination inhibition (HI) test. HI antibodies to reovirus were found in a high percentage of pigs, albino rats, Swiss mice, dogs and goats, and less frequently in rabbits, guinea pigs, Taiwan monkeys and buffalos.

Animals↗
PubMed1976

[Meningococcus group carrier status in Chinese recruits].

During the period, May 1974 approximately April 1975, 4 groups of Chinese basic training recruits from different cities in Taiwan were examined for cases of nasopharyngeal Neisseria meningitidis. Before training the carrier rate of N. meningitidis was 13.7%. However, 7 approximately 8 weeks after training the carrier rate had increased to 20%. The majority of strains isolated were serogroup A. However, serogroups C and B, in that order of frequency, were also isolated. Only four strains were serologically untypable. Of 344 strains tested for drug susceptibility, 186 (54.1)% of these strains were found to be resistant to sulfadiazine.

Carrier State↗
PubMed1975

[Isolation and characterization of a new picornavirus in Taiwan].

During the 1971 outbreaks of acute hemorrhagic conjunctivitis, 298 cases were admitted to the Veterans General Hospital and seven strains of new picornavirus were isolated in human epidermoid carcinoma cells. Two strains of the virus isolated have been further studied. Serological neutralization indicated that these isolates might represent a distinct picornavirus group. Biophysical and biological properties determined by this study indicated that the viruses had many characteristics in common with the echoviruses such as morphological appearance, lack of essential lipids, acid stability, density in cesium chloride, sedimentation rate, growth in the presence of 5-iodo-2-deoxyuridine 5-bromo-2-deoxyuridine and nonpathogenicity to suckling mice. However, they were differentiated into 2 strains on the basis of plaque size and neutralization kinetics.

Conjunctivitis↗
PubMed1975

[Identification of Group A streptococci from throats of school children in Northern Taiwan].

A total of 2,750 strains of beta-hemolytic streptococci was isolated from 10, 510 throat swabs collected from school children in the Taipei area. Most of them were classified as group A (61%) and group G (34%), and about 5% belonged to other groups or unclassified strains. 1, 772 strains of beta-hemolytic streptococci isolated from healthy school children, and 69 strains from sick school children were grouped by the Lancefield precipitin test, fluorescent antibody technique and/or bacitracin paper disk method. A satisfactory correlation (over 90%) was obtained by the latter 2 methods, when compared with the results of the Lancefield technique. The occurrance of false negative or false positive was only 1 or 5%, respectively.

Bacteriological Techniques↗