Search PubMed⌕ Search

Biomedical subjects

C L Hsieh

Publications and source records attributed to C L Hsieh.

121 records · Page 7Linked to original sources
PubMed1989

Chemical evidence for covalent linkages of a semi-synthetic glycoconjugate vaccine for Haemophilus influenzae type B disease.

We have defined the nature of the covalent linkages in a Haemophilus influenzae type b oligosaccharide-CRM197 conjugate vaccine, designated HbOC. The conjugate was acid hydrolyzed to release a novel amino-acid derivative, N epsilon-(2-hydroxyethyl)lysine (OHEt-Lys), identifiable with an amino-acid analyzer. This amino-acid derivative was formed by reduction of Schiff bases formed between H. influenzae type b oligosaccharides (HbO) and the lysyl epsilon-amino groups of CRM197 (a non-toxic, cross-reactive variant of diphtheria toxin), followed by acid hydrolysis of HbOC. Quantification of OHEt-Lys per CRM197 molecule allowed the determination of a covalency ratio, a useful parameter for evaluating the stoichiometry and consistency of HbOC preparations. Covalent association between HbO and CRM197 was also demonstrated by the coincidence of immunoreactivity of gel-electrophoresed HbOC on a Western blot probed with anti-CRM197 and anti-saccharide antisera.

Amino Acids↗
PubMed1989

Assignment of retinoblastoma susceptibility gene to mouse chromosome 14.

A human cDNA probe was used to screen a panel of mouse-Chinese hamster somatic cell hybrids to determine the chromosomal location of the retinoblastoma susceptibility gene (Rb-1) in mouse. The Rb-1 gene mapped to mouse chromosome 14. Thus, the retinoblastoma susceptibility gene is syntenic with esterase 10 (the mouse homolog of human esterase D). The chromosomal assignment of the mouse Rb-1 gene was further confirmed by using the same probe to study mouse-rat microcell hybrids. Since the human retinoblastoma susceptibility gene (RB1) along with the gene for esterase D is on chromosome 13q14, these data indicate this linkage group is conserved in man and mouse.

Animals↗
PubMed1989

Chromosome localization and cDNA sequence of murine and human genes for ras p21 GTPase activating protein (GAP).

The cDNA coding for mouse and human ras p21 GTPase-activating protein (GAP) was isolated; the deduced amino acid sequences share over 96% homology with that previously determined for bovine brain GAP. Both the mouse and human GAP cDNAs were used as probes for the chromosomal localization of this gene. The locus designations for the gene encoding GAP in human and mouse are RASA and Rasa (for ras-activating protein), respectively. By somatic cell hybrid analysis and in situ chromosomal hybridization, we have assigned the RASA gene to human chromosome band 5q13.3. In addition, with somatic cell genetics and linkage analysis in recombinant inbred mouse strains, the murine Rasa gene was localized to the distal end of mouse chromosome 13. These assignments place the gene encoding GAP in a known conserved syntenic region.

Amino Acid Sequence↗
PubMed1980

[A case report of variant form of multiple myeloma].

Multiple myeloma is usually manifested with multiple destructive bone lesion, plasmacytosis and monoclonal protein. Here in we report a case of IgA (lambda) multiple myeloma with hepatomegaly and anemia but without bone lesions. Differential diagnostic points among lymphoma, amyloidosis, cancer and heavy chain disease are discussed.

Anemia↗
PubMed1980

[Comparison of two hemagglutination tests for hepatitis B surface antigen (author's transl)].

Two commercial reverse passive hemagglutination tests of HBsAg (Organon and Wellcome) were compared and our results showed that both of them had excellent sensitivities. However, Wellcome excelled in specificities. The false positive test should be prevented by pretreatment of the serum. The hemagglutination may be comparable to the radioimmunoassay, if the specimens are adequately pretreated.

Hemagglutination Tests↗
PubMed1979

Time-resolved resonance Raman characterization of the bO640 intermediate of bacteriorhodopsin. Reprotonation of the Schiff base.

The resonance Raman spectrum of photolyzed bacteriorhodopsin under conditions known to increase the concentration of the bO640 intermediate in both H2O and D2O is presented. By use of computer subtraction techniques and a knowledge of the Raman spectra of the unphotolyzed bacteriorhodopsin as well as the other intermediates in the cycle, a qualitative spectrum of bO640 is determined. The shift of a band at 1630 cm-1 in H2O to 1616 cm-1 in D2O suggests that the Schiff base of bO640 is protonated. Additional bands at 947, 965, and 992 cm-1 that appear only in D2O suspensions confirm that a proton is coupled to the retinal chromophore of bO640. The reprotonation of the Schiff base thus occurs during the bM412 to bO640 step. The fingerprint region, sensitive to the isomeric configuration of the retinal chromophore of bO640, is dissimilar to the fingerprint regions of published model compounds and other forms of bacteriorhodopsin.

Bacteriorhodopsins↗
PubMed1979

Time-resolved resonance Raman characterization of the bL550 intermediate and the two dark-adapted bRDA/560 forms of bacteriorhodopsin.

The resonance Raman spectrum of the second intermediate in the bacteriorhodopsin cycle, bL550, is obtained by a simple flow technique. The Schiff base linkage in this intermediate appears to be protonated, contrary to previous suggestion. The fingerprint region of the spectrum of bL550 does not closely match those of any presently available model Schiff bases of retinal isomers, though some comparisons can be made. The resonance Raman spectrum of dark-adapted bacteriorhodopsin is obtained and decomposed by computer subtraction of the spectrum of bR570. The remaining spectrum does not match the spectra of any model compounds presently in the literature. The spectra of bL550 and dark-adapted bRDA/560 from purple membrane in H2O are compared to those in D2O. It is found that changes in the spectrum occur in the 1,600 - 1,650 cm-1 region as well as in the 800 - 1,000 cm-1 region, but apparently not in the fingerprint region (1,100 - 1,400 cm-1). The possibilities of conformational changes of the retinal chromophore in the light adaptation process as well as the photosynthetic cycle are discussed.

Bacteriorhodopsins↗
PubMed1979

Time-resolved resonance Raman spectroscopy of intermediates of bacteriorhodopsin: The bK(590) intermediate.

We have combined microbeam and flow techniques with computer subtraction methods to obtain the resonance Raman spectrum of the short lived batho-intermediate (bK(590)) of bacteriorhodopsin. Comparison of the spectra obtained in (1)H(2)O and (2)H(2)O, as well as the fact that the bK(590) intermediate shows large optical red shifts, suggests that the Schiff base linkage of this intermediate is protonated. The fingerprint region of the spectrum of bK(590), sensitive to the isomeric configuration of the retinal chromophore, does not resemble the corresponding region of the parent bR(570) form. The resonance Raman spectrum of bK(590) as well as the spectra of all of the other main intermediates in the photoreaction cycle of bacteriorhodopsin are discussed and compared with resonance Raman spectra of published model compounds.

Journal Article↗
PubMedDate not supplied

Effects of the garlic components diallyl sulfide and diallyl disulfide on arylamine N-acetyltransferase activity in human colon tumour cells.

Diallyl sulfide (DAS) and diallyl disulfide (DADS), major components of garlic, were used to determine inhibition of arylamine N-acetyltransferase (NAT) activity in a human colon tumour (adenocarcinoma) cell line. Two assay systems were performed, one with cellular cytosols (9000g supernatant), the other with intact bacterial cell suspensions. The NAT activity in a human colon tumour cell line was inhibited by DAS and DADS in a dose-dependent manner in both system: that is, the greater the concentration of DAS and DADS in the reaction, the greater the inhibition of NAT activities in both systems. The data also indicated that DAS and DADS decrease the apparent values of Km and Vmax of NAT enzymes from human colon tumour cells in both systems examined. This is the first report to demonstrate that garlic components do affect human colon tumour cell NAT activity.

2-Acetylaminofluorene↗
PubMedDate not supplied

The nonhomologous DNA end joining pathway is important for chromosome stability in primary fibroblasts.

There are two types of chromosome instability, structural and numerical, and these are important in cancer. Many structural abnormalities are likely to involve double-strand DNA (dsDNA) breaks. Nonhomologous DNA end joining (NHEJ) and homologous recombination are the major pathways for repairing dsDNA breaks. NHEJ is the primary pathway for repairing dsDNA breaks throughout the G0, G1 and early S phases of the cell cycle [1]. Ku86 and DNA ligase IV are two major proteins in the NHEJ pathway. We examined primary dermal fibroblasts from mice (wild type, Ku86(+/-), Ku86(-/-), and DNA ligase IV(+/-)) for chromosome breaks. Fibroblasts from Ku86(+/-) or DNA ligase IV(+/-) mice have elevated frequencies of chromosome breaks compared with those from wild-type mice. Fibroblasts from Ku86(-/-) mice have even higher levels of chromosome breaks. Primary pre-B cells from the same animals did not show significant accumulation of chromosome breaks. Rather the pre-B cells showed increased cell death. These studies demonstrate that chromosome breaks arise frequently and that NHEJ is required to repair this constant spontaneous damage.

Animals↗
PubMedDate not supplied

Regression of orthotopic brain tumors by cytokine-assisted tumor vaccines primed in the brain.

This study investigated the therapeutic effects of a rat glioma cell line, C6, that was engineered to secrete mouse GM-CSF (mGM-CSF) on intracerebral (i.c.) brain tumors. Significant antitumor immunity was induced in rats when the live or irradiated mGM-CSF-secreting tumor vaccine was implanted i.c. The antitumor activity was effective on small tumors and, to a lesser extent, on large tumors or tumors existing in vivo for a longer duration. Immunohistochemical analysis revealed cellular infiltrates (granulocytes, macrophages, and CD4+ and CD8+ T cells) at both the vaccine site and the tumor site, indicating that immune responses were similarly activated when tumor vaccine was inoculated in the brain, as at the subcutis. Additional studies demonstrated that the therapeutic effects of tumor vaccines on the large tumors or the long-existing tumors were enhanced by strategies such as increasing the dosage of tumor vaccines, using combined vaccines consisting of mGM-CSF and human interleukin-2, or combining tumor vaccine with herpes simplex virus thymidine kinase/ganciclovir treatment. All of the modified strategies yielded synergistic therapeutic effects on the large tumor burdens. The data presented herein suggest that cytokine gene therapy is highly promising for the treatment of i.c. gliomas.

Animals↗