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1.
Inhibition of methanogenesis in ruminal cultures was attempted by hindering thiamine availability through its degradation
by ‘polyphenols’ and competition for active sites on enzymes and transporters using thiamine structural analogs. Effects on
fermentation were small and not consistently reversed by adding thiamine. Lack of major effects of the compounds evaluated
could be due to intracellular synthesis of thiamine covering most requirements. 相似文献
2.
The occurrence and distribution of certain polypeptides within the human carotid body 总被引:3,自引:0,他引:3
Summary Both carotid bodies from 26 patients coming to necropsy were fixed in 10% neutral buffered formalin and sections 4 m thick were stained for various peptides by use of the immunogold technique. The results show that the human carotid body contains met- and leu-enkephalin, substance P, vasoactive intestinal peptide (VIP), neurotensin and bombesin. The distribution of these six peptides within the carotid body differs. Thus met- and leu-enkephalin are both present predominantly within glomic chief cells but with a marked tendency to favour the dark variant of these cells. Substance P and VIP both show a weak immunoreactivity in comparison to the enkephalins and are present in all three variants of chief cell. Neurotensin shows the weakest immunoreactivity of all and is restricted to a few glomic chief cells in a minority of cases. Bombesin also shows a weak immunoreactivity in glomic chief cells but a strong reaction in glomic arteries and arterioles. In these vessels bombesin appears to be confined to smooth muscle cells in the media but we cannot say whether it is secreted by them or merely bound to receptor sites on their membranes. These findings are related to quantitative data on the concentration of peptides in the human carotid body from a previous paper with which we were associated. 相似文献
3.
David E. Kerr Peter D. Senter William V. Burnett David L. Hirschberg Ingegerd Hellström Karl Erik Hellström 《Cancer immunology, immunotherapy : CII》1990,31(4):202-206
Summary The two monoclonal antibodies (mAb), L6 (anti-carcinoma), and 1F5 [anti-(B-cell-lymphoma)], were chemically linked to the enzyme penicillin-V amidase (PVA), which hydrolyzes phenoxyacetamides, to explore the potential of using mAb-enzyme conjugates for the localizaton of chemotherapeutic drugs at tumor cells. The phenoxyacetamide derivatives of doxorubicin and melphalan were prepared, yielding the less toxic amides, doxorubicin-N-p-hydroxyphenoxyacetamide (DPO) and melphalan-N-p-hydroxyphenoxyacetamide (MelPO). These were hydrolyzed by PVA to doxorubicin and melphalan respectively.In vitro studies with the L6-positive lung carcinoma cell line, H2981, and the 1F5-positive B-cell lymphoma line, Daudi, showed that DPO was 80-fold less toxic to H2981 cells and 20-fold less toxic to Daudi cells than doxorubicin, and its toxicity was substantially increased when the H2981 cells were pretreated with L6-PVA or the Daudi cells were pretreated with 1F5-PVA. The cytotoxic effect was antigen-specific, since only the binding mAb-enzyme conjugate increased the cytotoxicity of the prodrug. MelPO was more than 1000-fold less toxic than melphalan to H2981 cells and more than 100-fold less toxic than melphalan to Daudi cells. Pretreatment with the mAb-PVA conjugates did not enhance the toxicity of MelPO in either cell line, because PVA hydrolyzes the phenoxyacetamide bond of MelPO too slowly to generate a toxic level of melphalan. 相似文献
4.
Charles R. Ill Tammy Brehm Bjorn K. Lydersen Rachel Hernandez Karen G. Burnett 《In vitro cellular & developmental biology. Plant》1988,24(5):413-419
Summary Studies with Human x Human (HxH), Human x Mouse (HxM), and Mouse x Mouse (MxM) hybridomas have enabled us to define specific
factors that affect hybridoma growth in a species-specific manner. Three transferrins and three lipophilic iron chelates have
been tested for their ability to support hybridoma proliferation and antibody production. The results of these studies demonstrate
that HxH hybridomas do not respond to bovine transferrin a+ concentrations up to 100 μg/ml and are approximately 100-fold less responsive to mouse transferrin than to human transferrin.
HxM and MxM hybridomas respond equally to human or mouse transferrin but are 100-fold less sensitive to bovine transferrin.
An antibody to the human transferrin receptor inhibited the growth-promoting activity of human or mouse transferrin on HxH
hybridomas but was ineffective on HxM hybridomas. This semonstrated the functionality of the human transferrin receptor in
HxH hybridomas and that human, mouse, and bovine transferrin were interacting through the mouse transferrin receptor in HxM
hybridomas. HxH and HxM hybridomas respond similarly to three different iron chelates exhibiting 80 to 110% of the growth
response to human transferrin. MxM hybridomas fail to respond to the iron chelates at similar concentrations, suggesting that
the human genome present in the other hybridoma species confers a unique ability for utilizing iron when delivered in this
form. 相似文献
5.
P Trayhurn J S Keith P A Racey A M Burnett 《Comparative biochemistry and physiology. B, Comparative biochemistry》1991,99(2):317-320
1. Interscapular adipose tissue of suckling and adult pipistrelle bats was examined for the presence of the 32,000 Mr "uncoupling protein" diagnostic of brown adipose tissue. 2. Following separation by SDS-polyacrylamide gel electrophoresis, mitochondrial proteins were blotted onto nitrocellulose and probed for uncoupling protein with an anti-(ground squirrel uncoupling protein) serum. 3. Immunoreactivity consistent with the presence of uncoupling protein was found in all samples of adipose tissue mitochondria from both suckling and adult bats. 4. It is concluded that interscapular adipose tissue in pipistrelle bats exhibits the critical biochemical criterion for being designated functionally "brown". 相似文献
6.
Cells of the human promyelocytic HL60 line were induced to differentiate into granulocyte-like cells with dimethylsulphoxide (DMSO) or macrophage-like cells with 12-0-tetradecanoylphorbol-13-acetate (TPA). The synthesis of Cathepsin B by these cells was studied by immunoperoxidase staining and assay of cell lysates using the fluorimetric substrate benzoyloxycarbonyl-phenylanalyl-arginine-4-methyl-7-coumarylamide. Only 2–5% of the uninduced HL60 cells and DMSO-induced cells were immunohistochemically positive for Cathepsin B, compared with over 80% of the TPA-induced cells. Cathepsin B activity was lowest in the lysates of uninduced HL60s. DMSO-induced cells contained 1.5–2-fold the enzyme activity of HL60s and TPA-induced cell lysates demonstrated 5–14-fold the activity of uninduced HL60s. Induction of Cathepsin B synthesis was therefore associated with differentiation of the promyelocytes into cells of the monocyte/macrophage type, but not granulocyte-like cells. Cathepsin B was located immunohistochemically in human palatine tonsils. The enzyme was only demonstrated within macrophages in these tissues. Cathepsin B may therefore be a useful immunohistochemical marker for malignant and nonmalignant cells of the monocyte/macrophage lineage. 相似文献
7.
Binding of ethidium bromide to double-stranded ribonucleic acid 总被引:4,自引:0,他引:4
8.
J. Paul Burnett A. O. Summers J. A. Harrington A. C. Dwyer 《Applied microbiology》1968,16(8):1245-1250
A method is described for increasing the incorporation of radioactive thymidine into adenovirus deoxyribonucleic acid by the use of amethopterin. In addition, a modified procedure is presented for the preparation of highly purified adenoviruses. This procedure, which employs enzymatic digestion of cellular debris, obviates the necessity for fluorocarbon treatment of crude virus suspensions, and routinely provides excellent recovery of virus. 相似文献
9.
10.
Induction of bovine papillomavirus E2 gene expression and early region transcription by cell growth arrest: correlation with viral DNA amplification and evidence for differential promoter induction 总被引:9,自引:8,他引:1 下载免费PDF全文
S Burnett A C Strm N Jareborg A Alderborn J Dillner J Moreno-Lopez U Pettersson U Kiessling 《Journal of virology》1990,64(11):5529-5541