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21.
22.
The effect of phosphate on the binuclear iron center of pink (reduced) uteroferrin was examined by magnetic resonance and optical spectroscopy. The purple (oxidized) protein, which contains 1 mol of tightly bound phosphate per mol of enzyme at isolation, does not give rise to a 31P NMR signal. Phosphate binding to phosphate-stripped pink uteroferrin is indistinguishable from that in the native purple phosphoprotein. As measured by EPR and optical spectroscopy, the rate of reaction between phosphate and pink uteroferrin is pH-dependent, decreasing as the pH increases. Phosphate is capable of binding to the reduced protein between pH 3 and 7.8, resulting in formation of the purple uteroferrin-phosphate complex. Evans susceptibility measurements at pH 4.9 indicate that the EPR silent species with a maximum absorption at 535 nm, generated upon phosphate addition to pink uteroferrin, is diamagnetic. Moreover, phosphate causes disappearance of the hyperfine-shifted resonances in the 1H NMR spectra of the reduced protein. We therefore have not been able to identify the paramagnetic "purple reduced enzyme-phosphate complex" reported by Pyrz et al. (Pyrz, J. W., Sage, J. T., Debrunner, P. G., and Que, Jr., L. (1986) J. Biol Chem. 261, 11015-11020) using Mossbauer spectroscopy and dithionite-reduced 57Fe-reconstituted uteroferrin. Our present data with native unmodified enzyme are in accord with our earlier results (Antanaitis, B. C., and Aisen, P. (1985) J. Biol. Chem. 260, 751-756) and with the results of Burman et al. (Burman, S., Davis, J. C., Weber, M. J., and Averill, B. A. (1986) Biochem. Biophys. Res. Commun. 136, 490-497) on bovine spleen phosphatase, suggesting that phosphate binding to reduced protein rapidly induces oxidation of the binuclear iron center. 相似文献
23.
Forty cases of lymphoma were categorized as Burkitt-type lymphoma in a study of fine needle aspiration (FNA) smears. These constituted 14.3% of all cases of non-Hodgkin's lymphoma diagnosed between 1974 and 1982. The median age was 22 years in these cases, 81.8% of which had extranodal tumors. The majority of the cells in the smears (59.8% +/- 8.32%) were in the 11 micron to 15 micron size range and 60.3% +/- 10.3% had noncleaved nuclei. An average 71% of the cells contained cytoplasmic and/or nuclear vacuolizations. Nonneoplastic macrophages were present in the smears in 87.5% of the cases. A study of paraffin-embedded sections in 17 cases revealed the characteristic "starry-sky" appearance in 11; in 5 it was not clearly appreciated and in 1 the nonneoplastic macrophages were absent. FNA cytology was found to be quite reliable for arriving at a diagnosis of Burkitt-type lymphoma. More than 50% of the cases were managed without resort to subsequent surgical biopsy. Exploratory laparotomy was avoided in 69% of the cases having abdominal tumors. 相似文献
24.
Detection of human papillomavirus in cervical smears. A comparison of in situ hybridization, immunocytochemistry and cytopathology 总被引:3,自引:0,他引:3
A comparison of different methods for the detection of cervical human papillomavirus (HPV) infection was made on patients attending the cervical dysplasia clinic. Cytomorphology, immunocytochemistry and in situ hybridization were compared for their ability to detect HPV. Separate cervicovaginal smears from 50 patients were tested for HPV types 6/11, 16 and 18 by in situ hybridization using 35S-labeled DNA probes. Duplicate smears from the same patients were Papanicolaou stained and evaluated for evidence of condylomatous and dysplastic changes. Twenty-five matching cervical biopsies were immunostained for HPV capsid antigen and tested by in situ hybridization for HPV DNA. The cytologic smears of 20 patients (40%) were positive for HPV DNA. Six patients had HPV 6/11, ten had HPV 16, three had HPV 18, and one had both HPV 6/11 and HPV 16. There was a high correlation between condylomatous cytopathology and antigen and DNA detection. One-third of the specimens with condylomatous changes were DNA negative by the tested probes, suggesting the presence of other HPV types in the genital tract. 相似文献
25.
N J Pressman J K Frost P K Gupta R L Showers G W Gill D L Cook J K Frost R K Traub 《Analytical and quantitative cytology and histology / the International Academy of Cytology [and] American Society of Cytology》1987,9(4):291-302
Cellular dynamics often involve extremely low concentrations of biologically active substances, which can be radiolabeled and detected, localized and quantitated by autoradiography. The latter may require exposures from a few days to many months. The objective of this research was to demonstrate the feasibility of reducing this long period of data collection by one to two orders of magnitude, while maintaining or improving the spatial resolution and localization in tissues and the quantitative characteristics inherent in autoradiography. A mathematical model describing the complete system was generated using energy partition calculations to estimate photon production via scintillant per H3 beta particle emission and to estimate the subsequent photon capture based upon imaging system parameters and microscope geometry. Calculations showed that, typically, a single tritium beta particle produces a maximum of 5.8 X 10(3) photons. A photon-limited camera and microscope imaging system were selected and optimized in conjunction with a specially developed physical scintillation model. Results showed that the number of detected photoevents increases monotonically with both signal integration time and, independently, with the concentration of the radionuclide. Consequently, this work demonstrates that video microscopy imaging methods can spatially and temporally quantify very low concentrations of radiolabeled substances and can reduce data acquisition times. 相似文献
26.
Functional drug targeting to erythrocytes in vivo using antibody bearing liposomes as drug vehicles 总被引:2,自引:0,他引:2
A K Agrawal A Singhal C M Gupta 《Biochemical and biophysical research communications》1987,148(1):357-361
Covalent attachment of anti-erythrocyte F(ab')2 to the liposome surface has recently been shown to considerably enhance the liposome binding to erythrocytes in vivo. These antibody bearing liposomes have now been found quite effective as vehicles for delivering the antimalarial drug, chloroquine, to erythrocytes in Plasmodium berghei-infected mice. This demonstrates the usefulness of antibody targeted liposomes as carriers for site-specific drug delivery. 相似文献
27.
28.
R S Reid A L Stuart S V Gupta L J Latimer B L Haug J S Lee 《Nucleic acids research》1987,15(10):4325-4335
Synthetic DNAs were prepared containing 6-methyl adenine (m6A) in place of adenine and 5-ethyl uracil (Et5U) or 5-methoxymethyl uracil (Mm5U) in place of thymine. All three modifications destabilized duplex DNAs to varying degrees. The binding of ethidium was studied to analogues of poly[d(AT)]. There was no evidence of cooperative binding and the "neighbour exclusion rule" was obeyed in all cases although the binding constant to poly[d(m6AT)] was approximately 6 fold higher than to poly[d(AT)]. 31P NMR spectra were recorded in increasing concentrations of CsF. Poly[d(AEt5U)] showed two well-resolved signals separated by 0.55 ppm in 1 M CsF compared to 0.32 ppm for poly[d(AT)] under identical conditions. In contrast, poly[d(AMm5U)] and poly[d(m6AT)] showed two signals separated by 0.28 ppm and 0.15 ppm respectively, only when the concentration of CsF was raised to 2 M. The signals for poly[d(AT)] in 2 M CsF were better resolved and were separated by 0.41 ppm. These results suggest that minor modifications to the bases may have conformational effects which could be recognized by DNA-binding proteins. 相似文献
29.
Small mitochondrial DNA molecules of wild abortive cytoplasm in rice are not necessarily associated with CMS 总被引:2,自引:0,他引:2
N. M. Saleh B. J. Mulligan E. C. Cocking H. S. Gupta 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1989,77(5):617-619
Summary Mitochondrial DNA was isolated from leaf tissue of both the cytoplasmic male sterile line of Indica rice variety V41, which carries wild abortive (WA) cytoplasm, and from the corresponding maintainer line. In addition to the main mitochondrial DNA, four small plasmid-like DNA molecules were detected in both the male sterile and fertile lines. Restriction analysis of total mitochondrial DNA from the male sterile and fertile lines showed DNA fragments unique to each. Our findings suggest that the four small mitochondrial DNA (mtDNA) molecules are conserved when WA cytoplasm is transferred into different nuclear backgrounds. However, there is no simple correlation between the presence/ absence of small mitochondrial DNA molecules and the expression of WA cytoplasmic male sterility (CMS). 相似文献
30.
Sudhir Gupta 《Molecular and cellular biochemistry》1989,91(1-2):45-50
Several monoclonal antibodies directed against a number of T cell surface molecules are used to elucidate the role of these molecules (cell surface molecules) in T cell activation. The activation of T cells via these molecules are both antigen-dependent (CD3/TcR complex) and antigen-independent. Irrespective of their antigen-dependency, these monoclonal antibodies activate T cells by a classical signal transduction pathway, in which the binding of monoclonal antibodies to their cell surface receptors leads to activation of phospholipase C resulting in the the depolarization of plasma membrane, hydrolysis of IP2 and IP3 and DAG, the second messengers. IP3 leads to mobilization of intracellular calcium to contribute to an increase in [Ca++]i, whereas DAG causes activation and translocation of PKC and an increasing apparent affinity for Ca++. The role of IN in the mobilization of intracellular calcium is emerging. In addition, influx of extracellular calcium also contributes to increase in [Ca–+];. The increase in [Ca++]; following activation via some T cell surface antigen is predominantly due to intracellular mobilization of Ca–+ (e.g. CD3/TcR complex), whereas activation via other T cell surface antigen, the increase in [Ca+–]i is almost entirely due to an influx of extracellular calcium (e.g. CD5 antigen). All these molecules activate autocrine system of T cell growth, namely IL-2 production, IL-2 receptor expression and T cell proliferation. 相似文献