Search PubMed⌕ Search

Biomedical subjects

T Zhao

Publications and source records attributed to T Zhao.

At least 109 records · Page 6Linked to original sources
PubMed1993

Fate of enterohemorrhagic Escherichia coli O157:H7 in apple cider with and without preservatives.

A strain of enterohemorrhagic Escherichia coli serotype O157:H7 isolated from a patient in an apple cider-related outbreak was used to study the fate of E. coli O157:H7 in six different lots of unpasteurized apple cider. In addition, the efficacy of two preservatives, 0.1% sodium benzoate and 0.1% potassium sorbate, used separately and in combination was evaluated for antimicrobial effects on the bacterium. Studies were done at 8 or 25 degrees C with ciders having pH values of 3.6 to 4.0. The results revealed that E. coli O157:H7 populations increased slightly (ca. 1 log10 CFU/ml) and then remained stable for approximately 12 days in lots inoculated with an initial population of 10(5) E. coli O157:H7 organisms per ml and held at 8 degrees C. The bacterium survived from 10 to 31 days or 2 to 3 days at 8 or 25 degrees C, respectively, depending on the lot. Potassium sorbate had minimal effect on E. coli O157:H7 populations, with survivors detected for 15 to 20 days or 1 to 3 days at 8 or 25 degrees C, respectively. In contrast, survivors in cider containing sodium benzoate were detected for only 2 to 10 days or less than 1 to 2 days at 8 or 25 degrees C, respectively. The highest rates of inactivation occurred in the presence of a combination of 0.1% sodium benzoate and 0.1% potassium sorbate. The use of 0.1% sodium benzoate, an approved preservative used by some cider processors, will substantially increase the safety of apple cider in terms of E. coli O157:H7, in addition to suppressing the growth of yeasts and molds.

Benzoates↗
PubMed1993

[A comparison of proliferating cell nuclear antigen immunostaining, nucleolar organizer region staining in lung cancer].

Seventy-three cases of lung cancer were studied using two different methods, immunostaining for the proliferating cell nuclear antigen (PCNA) and nucleolar organizer region staining (AgNORs), to assess the degree of cell proliferation. Both PCNA immunostaining and AgNOR staining were found to be significantly correlated with histological grade of lung cancer. The mean number of AgNOR per nucleus was found to be associated with LI of PCNA (r = 0.70, P < 0.01). The results suggest that the two proliferation-associated factors may be used as the additional diagnostic parameters in the grading of lung cancer.

Adenocarcinoma↗
PubMed1993

[Allelic polymorphism in the coding region of human T cell receptor V beta 12 gene].

Sequence substitutions in T cell antigen receptor (TCR) beta chains have been shown to have a profound impact upon the fine specificity of T lymphocytes. It is, therefore, of interest to characterize allelic variations in the TCR gene segments that assemble to encode TCR molecules. In the present report, the sensitive technique of single stranded conformational polymorphism (SSCP) was used to screen for allelic sequence variations in the coding region of TCR V beta 12 gene. TCR V beta 12 specific primers were used to PCR amplify and 32P label a 273bp segment of the variable (V) gene segment. Sequence differences between different allelic forms were detected by denaturation of the DNA and separation on a non-denaturing, high resolution acrylamide gel. Using this rapid approach, four alleles of the TCR V beta 12 gene were detected in a population of 90 ethnically diverse individuals. Correct Mendelian segregation of the four alleles was demonstrated in family studies (n = 23) and allele frequencies were 0.4722, 0.3166, 0.2056, and 0.0056 respectively. Sequence analysis revealed sequence differences of 1-3 nucleotides involving three separate codons. However, predicted amino acid sequences of all four alleles are identical. These data strongly suggest that the TCR V beta 12 protein sequence is highly conserved.

Alleles↗
PubMed1992

Silent allelic variants of a T-cell receptor V beta 12 gene are present in diverse human populations.

Amino acid substitutions in variable regions of the T-cell receptor (TCR) can alter T-cell reactivity; however, relatively little is known about the extent of allelic variation in human TCR coding sequences. In the present studies, coding region variation in the human TCR V beta 12.2 gene was examined in detail. Virtually the entire V beta 12.2 coding region was screened for nucleotide substitutions by single-stranded conformational polymorphism analysis. Four alleles were identified in a sample population of 90 unrelated people from diverse genetic backgrounds. Three of the alleles were common, with estimated frequencies of 0.32, 0.47, and 0.20. Sequence analyses revealed that variation between the alleles was confined to three single-base differences in codons 24, 31, and 45; none of these changes altered the amino acid sequence. No evidence for other coding region differences in this gene were found. This analysis suggests that coding region variation in V beta 12.2 is limited, and amino acid sequence is highly conserved.

Alleles↗
PubMed1989

Production and characterisation of monoclonal antibodies to Verotoxins 1 and 2 from Escherichia coli of serotype O 157:H7.

Fourteen hybridoma cell lines were isolated that produced monoclonal antibodies (MAbs) to purified Verotoxins 1 and 2 (VT1, VT2) of Escherichia coli of serotype O157:H7. Of these MAbs, eight were obtained by immunisation of BALB/c mice with purified VT1, and six were obtained from BALB/c mice immunised with purified VT2. With the exception of MAb 1C5, with a heavy chain of IgG2b class, antibodies produced from mice immunised with heat-treated toxin were of IgM class. MAbs produced from mice immunised with heat-treated VT1 or VT2 reacted with both verotoxins in ELISA, and Western-blot analysis revealed that they reacted with subunit A and the A1 fragment of nicked subunit A of both toxins, but not with subunit B; furthermore, none of them neutralised Vero cytotoxicity or mouse lethality of either toxin. In contrast, MAbs produced from mice immunised with heat-treated and formalin-treated VT1 reacted in Western blots with subunits A and B of VT1 and subunit A, but not subunit B, of VT2, reacted in ELISA with VT1 only, and neutralised Vero cytotoxicity and mouse lethality of VT1 but not of VT2. Results indicate the existence of a common epitope on subunit A of VT1 and VT2 that is not responsible for the biological activity of these toxins, and that subunit B is essential for the biological activity of VT1. MAbs capable of reacting with both verotoxins from E. coli of serotype O157:H7 may be useful reagents for screening bacterial isolates capable of producing one or both of these toxins.

Animals↗
PubMed1988

Treatment of postmenopausal breast cancer with bisbromoacetyl hexestrol.

Twenty five cases of advanced postmenopausal breast cancer patients were treated with bisbromoacetyl hexestrol 3 CR and 5 PR were achieved. The response rate was 32%, and the average duration of remission 6 months. Vaginal bleeding was seen in 9 cases, 4 of whom were compelled to discontinue treatment.

Aged↗
PubMed1983

HLA-A, B and HLA-DR phenotypes in Mainland Chinese patients with diabetes mellitus.

HLA-A, B and DR antigens were studied in Mainland Chinese diabetes mellitus patients and controls (31 Type I DM, 50 Type II DM, 105 controls). HLA-DR3 and HLA-A9 were increased in Type I diabetics only. An increase in HLA-DR4 was noted in Type I diabetics, but the increase was not statistically significant in this small series.

Adolescent↗