576
|
Kamber EY, Cocke CL, Cheng S, Varghese SL. Differential cross sections for multiple ionization of Ne and Ar in collisions with fast protons. PHYSICAL REVIEW. A, ATOMIC, MOLECULAR, AND OPTICAL PHYSICS 1990; 41:150-157. [PMID: 9902854 DOI: 10.1103/physreva.41.150] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
|
577
|
Cheng S, Komi PV, Kyröläinen H, Kim DH, Häkkinen K. In vivo vibrational wave propagation in human tibiae at different ages. EUROPEAN JOURNAL OF APPLIED PHYSIOLOGY AND OCCUPATIONAL PHYSIOLOGY 1989; 59:128-30. [PMID: 2583141 DOI: 10.1007/bf02396590] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Vibrational wave propagation was tested in vivo on the tibial bone of both legs of 56 female volunteers. The impact was produced by a hammer with a force strain gauge and the response was monitored by two accelerometers. The peak amplitude of the accelerations, the velocity of the acceleration wave propagation and damping were analysed for comparison among the different age groups. The results showed significant negative correlations between age and the peak amplitude of acceleration, and the velocity of acceleration wave propagation (p less than 0.01). The damping time of the acceleration wave also had a negative correlation with age. These findings suggested that age differences were related to the differences in the mechanical properties of bone. With reduction of bone mineral density, the velocity of the vibrational wave propagation would decrease, with simultaneous increase in impedance. In addition, wave absorption would be accelerated. It is suggested that this method could be used as an indicator of bone density. The method could also be developed to provide an index to monitor the progress of osteoporosis.
Collapse
|
578
|
Abstract
One hundred fifty-one total colonoscopies were performed in 105 children ranging from 1 month to 15 years of age. The cecum was reached successfully in 136 examinations without complications, generally within 30 minutes. Our major indications for total colonoscopy were abnormal findings in a contrast enema, undiagnosed rectal bleeding, and possible organic lesion causing intussusception. All procedures were performed using sedation only. The pediatric gastroscope was employed for total colonoscopy on infants less than 6 years of age; the cecum was reached successfully in 98 of 106 procedures with this instrument. Our total colonoscopy series contributed to the diagnosis of various disorders in 86 children and of normality in the 19 remaining children. The results suggest that, if performed with proper precautions and techniques, total colonoscopy is a safe and useful procedure with which to examine the entire colon of infants and children.
Collapse
|
579
|
Cheng S, Rogers JC. Changes in occupational role performance after a severe burn: a retrospective study. Am J Occup Ther 1989; 43:17-24. [PMID: 2923171 DOI: 10.5014/ajot.43.1.17] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Ten men with severe burn injuries were interviewed to examine their perceptions of the residual impact of severe burn on performance in self-care, home management, work, and leisure occupations within the year after rehabilitation. Three patterns of occupational role performance after a burn were identified: (a) a resumption of participation in all four occupational categories; (b) a return to independence in self-care with substantive impairment in home management, work, and/or leisure roles; and (c) substantive disruption in all occupational roles. Role loss or disruption was commonly associated with reduced endurance, intolerance for standing and walking, and impaired grip strength and upper extremity skill. Suggestions for rehabilitation programming and research are made.
Collapse
|
580
|
Fu B, Bai X, Cheng S. The temperature difference across the cell membrane during phase change. Cryobiology 1988. [DOI: 10.1016/0011-2240(88)90406-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
|
581
|
Jull AJ, Cheng S, Gooding JL, Velbel MA. Rapid Growth of Magnesium-Carbonate Weathering Products in a Stony Meteorite from Antarctica. Science 1988; 242:417-9. [PMID: 17789812 DOI: 10.1126/science.242.4877.417] [Citation(s) in RCA: 73] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Nesquehonite, a hydrous magnesium carbonate, occurs as a weathering product on the surface of the Antarctic meteorite LEW 85320(H5 chondrite). Antarctic meteorites have resided on the earth for periods of 10(4) to 10(6) years, but the time needed for weathering products to form has been uncertain. Isotopic measurements of delta(13)C and delta(18)O indicate that the nesquehonite formed at near freezing temperatures by reaction of meteoritic minerals with terrestrial water and carbon dioxide. Results from carbon-14 dating suggest that, although the meteorite has been in Antarctica for at least 3.2 x 10(4) to 3.3 x 10(4) years, the nesquehonite formed after A.D.1950.
Collapse
|
582
|
Cheng S, Van Houten B, Gamper HB, Sancar A, Hearst JE. Use of psoralen-modified oligonucleotides to trap three-stranded RecA-DNA complexes and repair of these cross-linked complexes by ABC excinuclease. J Biol Chem 1988; 263:15110-7. [PMID: 2844801] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
A series of site-specifically cross-linked, three-stranded complexes has been prepared using the RecA protein, form I (covalently closed and negatively supercoiled) pUC19 plasmid, and eight psoralen-monoadducted oligonucleotides between 30 and 107 residues in length. Complexes formed much less efficiently if linearized pUC19 was used as the duplex substrate. Quantitative analysis indicates that although RecA is able to utilize a 30-mer in its homologous pairing reaction, incorporation at 50% efficiency requires a single-stranded substrate at least 50 residues long. These three-stranded complexes have been used to study the action mechanism for cross-link repair by ABC excinuclease, and the results are consistent with the recent model of Van Houten, B., Gamper, H., Holbrook, S. R., Hearst, J. E., and Sancar, A. (1986b) Proc. Natl. Acad. Sci. U. S. A. 83, 8077-8081.
Collapse
|
583
|
Cheng S, Van Houten B, Gamper HB, Sancar A, Hearst JE. Use of psoralen-modified oligonucleotides to trap three-stranded RecA-DNA complexes and repair of these cross-linked complexes by ABC excinuclease. J Biol Chem 1988. [DOI: 10.1016/s0021-9258(18)68152-9] [Citation(s) in RCA: 63] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
|
584
|
Cheng S, Vogel R, Ye W, Blume M, Lee S, Hung P. The core gene of hepatitis B virus; subtype adw2. Nucleic Acids Res 1988; 16:8188. [PMID: 3419915 PMCID: PMC338533 DOI: 10.1093/nar/16.16.8188] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
|
585
|
Cheng S, Lamont SJ. Genetic analysis of immunocompetence measures in a White Leghorn chicken line. Poult Sci 1988; 67:989-95. [PMID: 3265514 DOI: 10.3382/ps.0670989] [Citation(s) in RCA: 133] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Immunocompetence of the Iowa State University S1 White Leghorn chicken line was studied. This line was divided into eight sublines based upon erythrocyte antigen B (Ea-B) allele (B1B1 or B19B19), antibody response to glutamic acid60-alanine30-tyrosine10 (GAT) (high or low), and response to Rous sarcoma virus-induced tumors (progression or regression). Antibody responses to Pasteurella multocida (PM), Mycoplasma gallisepticum (MG), and infectious bursal disease virus vaccines were evaluated by enzyme-linked immunosorbent assay. Phagocytic activity and T cell-mediated response were measured by carbon clearance and phytohemagglutinin (PHA) injection assays, respectively. Significant haplotype (subline) differences and sire family differences were observed in all three measurements. Significant sex differences were observed in phagocytic activity and T cell-mediated responses. Haplotypes with high antibody responses to GAT had significantly higher antibody titers to PM and MG vaccines than haplotypes with low antibody responses. Significant positive correlations were observed between antibody levels to the two vaccines. A significant negative correlation was seen between phagocytic activity and T cell-mediated response of females. The data suggest that the total immunocompetence profile of an individual must be considered to select for optimum immune responsiveness.
Collapse
|
586
|
Nordskog AW, Cheng S. Inbreeding effects on fertility and hatchability associated with the formation of sublines. Poult Sci 1988; 67:859-64. [PMID: 3413010 DOI: 10.3382/ps.0670859] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
The deleterious effect of inbreeding on fertility and hatchability was studied in a population of Leghorns developed primarily for immunogenetics studies. The 1983 population averaged 42% inbreeding and traced back to only two sires and five dams of the 1965 base population. Up to 1975 (Period 1), the population was maintained as a single-unit closed flock, during which time inbreeding increased an average of 1.44% per year. After 1975 (Period 2), the population was split into five sublines. Inbreeding then increased at the average rate of 2.7% per year. The regression of fertility on inbreeding was -.31 +/- .04 in Period 1 and -.17 +/- .06 in Period 2. Corresponding values for hatchability of fertile eggs were +.08 +/- .05 in Period 1 and -.24 +/- .07 in Period 2. The regression of hatchability of total eggs set was -.15 +/- .04 in Period 1 and -.35 +/- .10 in Period 2. The evidence implies that both fertility and hatchability have a heritable basis. As expected, the deleterious effects of inbreeding on reproduction was more severe in Period 2, with sublining.
Collapse
|
587
|
Kamber EY, Cocke CL, Cheng S, Varghese SL. Angular distribution of fast protons from singly and doubly ionizing collisions with He. PHYSICAL REVIEW LETTERS 1988; 60:2026-2029. [PMID: 10038238 DOI: 10.1103/physrevlett.60.2026] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
|
588
|
Cheng S. [Observations by quantitative electron microscopy of the action of zinc in protecting the liver from cadmium damage]. ZHONGHUA YU FANG YI XUE ZA ZHI [CHINESE JOURNAL OF PREVENTIVE MEDICINE] 1988; 22:161-3. [PMID: 3197525] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
|
589
|
Cheng S, Chen YL. Study on erythrocyte membrane fluidity by laser Raman spectroscopy. CELL BIOLOGY INTERNATIONAL REPORTS 1988; 12:205-11. [PMID: 3383249 DOI: 10.1016/0309-1651(88)90097-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Differences between patients with cirrhosis of liver, nephrotic syndrome, coronary heart disease and normal subjects in laser Raman spectra of erythrocyte membranes have been found. In regions of 1000-1140 cm-1 and 2840-3000 cm-1, the ratios I1130/I1080 and I2890/I2850 in patient membranes are higher than those in normal ones respectively. These results mean that erythrocyte membrane fluidity of these patients is reduced. This reduction may be attributed to the possibility that erythrocyte membrane of patients get more cholesterol from their plasma and resulted in the modification of the ratio of cholesterol/phospholipids in the membranes.
Collapse
|
590
|
Chen KY, Cheng S. Polyamine metabolism in an obligately alkalophilic Bacillus alcalophilus that grows at pH 11.0. Biochem Biophys Res Commun 1988; 150:185-91. [PMID: 2447890 DOI: 10.1016/0006-291x(88)90503-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Bacillus alcalophilus, an obligately alkalophilic bacterium that grows at pH 11.0, has an intracellular pH of 9.5 or less. Unlike all other living organisms, polyamines (putrescine, spermidine and spermine) in B. alcalophilus, if present, will be largely unprotonated. HPLC analysis indicated that spermidine is the major polyamine in B. alcalophilus, accounting for more than 90% of total polyamines, and the level of spermidine varies during growth. Ornithine decarboxylase activity was not detectable in B. alcalophilus under all conditions examined. When [3H]arginine was added to the culture medium, the radioactivity can be recovered from polyamine pool; the distribution is 3% for putrescine, 94% for spermidine, and 3% for spermine, suggesting the presence of arginine pathway for polyamine biosynthesis. The polyamine transport system in B. alcalphilus appears to be Na+-dependent and is highly sensitive to the inhibition of gramicidin S and valinomycin.
Collapse
|
591
|
Cheng S. [Metallothionein]. SHENG LI KE XUE JIN ZHAN [PROGRESS IN PHYSIOLOGY] 1987; 18:352-4. [PMID: 3330873] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
|
592
|
Daldal F, Davidson E, Cheng S. Isolation of the structural genes for the Rieske Fe-S protein, cytochrome b and cytochrome c1 all components of the ubiquinol: cytochrome c2 oxidoreductase complex of Rhodopseudomonas capsulata. J Mol Biol 1987; 195:1-12. [PMID: 2821266 DOI: 10.1016/0022-2836(87)90322-6] [Citation(s) in RCA: 67] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The structural genes for the Rieske Fe-S protein (petA), cytochrome b (petB) and cytochrome c1 (petC) subunits of the ubiquinol:cytochrome c2 oxidoreductase (bc1 complex) of Rhodopseudomonas capsulata have been cloned by complementation, using a mutant defective in this complex. The location of these genes on the obtained plasmid, pR14A, was determined using synthetic mixed oligonucleotide probes corresponding to highly conserved amino acid sequences of these proteins from various organisms. Their correct identity was established by partial sequencing. The petA, petB and petC genes were found to lie close to each other in this order, spanning two adjacent EcoRI fragments of 2.7 X 10(3) and 1.3 X 10(3) base-pairs, respectively. An insertion-deletion mutation, covering most of petB and all of petC and an insertion mutation, located in petB were constructed in vitro and were introduced into the chromosome of an otherwise wild-type strain by gene transfer agent-mediated genetic crosses. The bc-1 mutants obtained were defective in photosynthesis but, as expected, they could grow by respiration because of a branched respiratory pathway. Therefore, in R. capsulata a functional bc1 complex is essential in vivo for photosynthesis but not for respiration. Further, in the respiratory pathway the branch point must be before the bc1 complex, most likely at the quinone pool. These mutants were also proficient in anaerobic growth in the presence of dimethylsulfoxide, indicating that a functional bc1 complex is not required for this pathway. Several other insertions and deletions, located outside of the pet gene cluster, were also constructed. The ability of these latter mutants to grow photosynthetically suggested that no other gene essential for photosynthesis is located in the proximity of the pet cluster. The plasmid pR14A was shown to complement in trans the bc-1 insertion or insertion-deletion mutants, indicating that the pet genes were expressed in R. capsulata. Cross-hybridization experiments showed that the pet cluster was quite distinct from other known genes involved in photosynthesis.
Collapse
|
593
|
Groscurth P, Cheng S, Vollenweider I, von Felten A. Effects of washing and gel filtration on the ultrastructure of human platelets. Acta Haematol 1987; 77:150-5. [PMID: 3113155 DOI: 10.1159/000205980] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The ultrastructure of washed and gel-filtered platelets has been examined by scanning- and transmission-electron microscopy. Three different washing procedures previously established for functional studies have been employed. Each washing method resulted in typical morphologic alterations of the platelets. Gel filtration of platelet-rich plasma appeared less harmful than washing. Specimens fixed immediately after elution contained numerous platelets with typical shape changes which were restored almost completely after incubation at 37 degrees C. Our study emphasizes the need for cautious interpretation of results obtained with separated platelets and mandates morphologic controls for such experiments.
Collapse
|
594
|
Hasumura S, Kitagawa S, Lovelace E, Willingham MC, Pastan I, Cheng S. Characterization of a membrane-associated 3,3',5-triiodo-L-thyronine binding protein by use of monoclonal antibodies. Biochemistry 1986; 25:7881-8. [PMID: 3542039 DOI: 10.1021/bi00372a014] [Citation(s) in RCA: 34] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Four mouse hybridoma cell lines have been isolated which secrete antibodies to the membrane-associated thyroid hormone binding protein (Mr 55,000) from human epidermoid carcinoma A431 cells. J6 is rat specific; J2 is human and monkey specific; J8 and J9 have a wider specificity and react with similar thyroid hormone binding proteins (p55) from human, monkey, rat, and hamster. None of these antibodies reacts with mouse cells. J2, J6, and J9 are of the IgG1k class, and J8 is an IgAk antibody. p55 was characterized by using these monoclonal antibodies. It is not posttranslationally processed by glycosylation, phosphorylation, or sulfation. It has a cellular degradation rate t1/2 approximately equal to 3.2 h. Using immunofluorescence and electron microscopic immunocytochemistry, p55 was found to be associated with the lumenal face of the endoplasmic reticulum and nuclear envelope. When cell homogenates were prepared, significant amounts of p55 were released into the 110000g supernatant, indicating that p55 is loosely associated with the endoplasmic reticulum and nuclear envelope.
Collapse
|
595
|
Rogers JA, Cheng S, Betageri GV. Association and partitioning of propranolol in model and biological membranes. Biochem Pharmacol 1986; 35:2259-61. [PMID: 3729981 DOI: 10.1016/0006-2952(86)90602-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
|
596
|
Friedman SJ, Cheng S, Skehan P. Mechanisms of cholesterol synthesis inhibition by D-glucosamine. CANADIAN JOURNAL OF BIOCHEMISTRY AND CELL BIOLOGY = REVUE CANADIENNE DE BIOCHIMIE ET BIOLOGIE CELLULAIRE 1985; 63:1253-7. [PMID: 3830348 DOI: 10.1139/o85-157] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
The amino sugar D-glucosamine possesses antitumor activity which is thought to depend in part upon its ability to impair cholesterol biosynthesis and damage cellular membranes. The present study examined the effect of glucosamine on acetate utilization for lipid and sterol synthesis in rat C6 glial tumor cells. At cytotoxic concentrations, the amino sugar inhibited [14C]acetate incorporation into nonesterified sterols and lipids but increased the flow of label into cholesteryl esters. A comparison of the rates of acetate utilization for glucosamine metabolism (N-acetylation) and sterol and lipid synthesis suggested that glucosamine might act by competing for a common cytosolic pool of acetyl CoA. The inhibition of lipid and sterol synthesis, however, remained constant over a wide range of extracellular acetate concentrations. These results suggest that, if glucosamine acts by restricting the supply of acetate for these biosynthetic processes, it probably inhibits a step prior to the formation of acetyl CoA. Alternative mechanisms are discussed.
Collapse
|
597
|
Thompson SE, Brooks C, Eschenbach DA, Spence MR, Cheng S, Sweet R, McCormack WM. High failure rates in outpatient treatment of salpingitis with either tetracycline alone or penicillin/ampicillin combination. Am J Obstet Gynecol 1985; 152:635-41. [PMID: 3895937 DOI: 10.1016/s0002-9378(85)80036-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Eight hundred twenty-five ambulatory women with a clinical diagnosis of salpingitis were randomized to a 10-day course of either penicillin/ampicillin or tetracycline. Forty-four percent of women had gonococcal salpingitis and 56% nongonococcal salpingitis. Overall, both regimens cured equal proportions of women: At 30 days, 81% were cured by penicillin/ampicillin and 82% by tetracycline. However, the proportion of women with gonococcal salpingitis cured by 30 days was significantly greater than that of women with nongonococcal salpingitis. By 30 days, 14% of women with gonococcal salpingitis and 21% of women with nongonococcal salpingitis were not cured by either regimen. These data suggest that both regimens were only marginally acceptable for women with gonococcal salpingitis and that neither regimen was acceptable for nongonococcal salpingitis.
Collapse
|
598
|
Alderson R, Pastan I, Cheng S. Characterization of the 3,3',5-triiodo-L-thyronine-binding site on plasma membranes from human placenta. Endocrinology 1985; 116:2621-30. [PMID: 2986957 DOI: 10.1210/endo-116-6-2621] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The binding of [125I]T3 to sites on human placenta plasma membranes was characterized, and the binding site was solubilized after affinity labeling with N-bromoacetyl-[125I]T3 (BrAc[125I]T3). Two classes of T3-binding sites were detected. One class has a high affinity (Kd = 2.0nM) and a low capacity (approximately 320 fmol/mg protein); the other has a low affinity (Kd = 18.5 microM) and a high capacity (approximately 2.2 pmol/mg protein). The binding sites were found to be specific for T3 in that other thyroid hormone analogs (D-T3, rT3, D-T4, and L-T4) were less effective or ineffective in displacing the bound [125I]T3. The affinity labeling ligand BrAc[125I]T3 was found to specifically label a protein with an apparent mol wt of 65,000, as determined by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate. The BrAc[125I]T3-labeled protein was solubilized with 2 mM 3-[( 3-cholamidopropyl)dimethylammonio]1-propane sulfonate. The apparent mol wt of the labeled protein was between 140,000 and 150,000 by Sephadex-G-200 gel filtration. These data demonstrate that a high affinity binding site specific for T3 is present on plasma membranes from human placenta and that the binding site is a protein, most likely a dimer, with a native mol wt between 140,000 and 150,000.
Collapse
|
599
|
Cheng S. Structural similarities between the plasma membrane binding sites for L-thyroxine and 3,3',5-triiodo-L-thyronine in cultured cells. JOURNAL OF RECEPTOR RESEARCH 1985; 5:1-26. [PMID: 2987492 DOI: 10.3109/10799898509041868] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Using 125I-labeled L-thyroxine (T4), the binding of [125I]T4 to GH3 rat pituitary tumor cells was studied. At 15 degrees C, the binding of [125I]T4 to cells is saturable and specific. Least squares analysis of binding data showed two classes of binding sites with apparent dissociation constants of 4.3 +/- 0.3 nM and 350 +/- 30nM and binding capacities of (3.8 +/- 0.5) X 10(4) and (9.1 +/- 0.35) X 10(6) sites/cell, respectively. Affinity labeling of cells or purified plasma membranes with N-bromoacetyl-[125I]T4 (BrAc[125I]T4) showed a major specifically labeled protein band with an apparent molecular mass of 55 kilodaltons (kDal). Digestion of the 55-kDal protein from cells and plasma membrane by Staphylococcus aureus V8 protease or elastase gave similar peptide fragments. Thus, the 55-kDal protein labeled from intact cells is the same protein as that from purified plasma membranes. Peptide mapping was further used to compare the 55-kDal protein specifically labeled by either N-bromoacetyl-3,[125I]3',5-triiodo-L-thyronine (BrAc[125I]T3) or BrAc[125I]T4 in intact cells and highly purified plasma membranes. Very similar patterns were obtained. These results indicate that plasma membrane T3 and T4 binding sites have similar hormone binding domains. In addition the plasma membrane T3 and T4 binding sites of Swiss 3T3-4 mouse fibroblasts and A431 human epithelioid carcinoma cells are structurally similar to the T3 and T4 binding sites of GH3 cells.
Collapse
|
600
|
Hasumura S, Rossi B, Alderson R, Pastan I, Cheng S. Antibodies against the plasma membrane 3,3',5-triiodo-L-thyronine binding protein of rat pituitary GH3 cells: partial characterization and cross-species immunoreactivity. Biochem Biophys Res Commun 1984; 124:956-62. [PMID: 6095830 DOI: 10.1016/0006-291x(84)91051-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
To develop antibodies against the plasma membrane 3,3',5-triiodo-L-thyronine (T3) binding protein (M.W. 55,000), rabbits were immunized with formalin-fixed GH3 cells or highly purified plasma membranes from these cells. Antibodies were screened by immunoprecipitation using detergent solubilized N-bromoacetyl-[125I]T3-labeled 55K protein. Among the nine detergents tested, 0.18% CHAPS was found to be the best in its solubilization efficiency and its ability to maintain the integrity of the antigenicity of the 55K protein. The N-bromoacetyl-[125I]T3-labeled 55K protein was also immunoprecipitated by anti-T3 antibodies. The anti-55K protein antibodies cross-reacted with plasma membrane T3 binding proteins from cultured cells and tissues of human and rodent origin. These results indicate that structural similarities exist in human and rodent plasma membrane T3 binding proteins. These antibodies should provide a powerful tool in the characterization and in probing the function(s) of the plasma membrane T3 binding protein in cells.
Collapse
|