401
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Kaul R, Casanova J, Johnson AB, Tang P, Matalon R. Purification, characterization, and localization of aspartoacylase from bovine brain. J Neurochem 1991; 56:129-35. [PMID: 1987315 DOI: 10.1111/j.1471-4159.1991.tb02571.x] [Citation(s) in RCA: 85] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Canavan disease, an autosomal recessive disorder, is characterized biochemically by N-acetylaspartic aciduria and aspartoacylase (N-acyl-L-aspartate amidohydrolase; EC 3.5.1.15) deficiency. However, the role of aspartoacylase and N-acetylaspartic acid in brain metabolism is unknown. Aspartoacylase has been purified to apparent homogeneity with a specific activity of approximately 19,000-20,000 nmol of aspartate released/mg of protein. The native enzyme is a 58-kDa monomer. The purified aspartoacylase activity is enhanced by divalent cations, nonionic detergents, and dithiothreitol. Low levels of dithiothreitol or beta-mercaptoethanol are required for enzyme stability. Aspartoacylase has a Km of 8.5 x 10(-4) M and a Vmax of 43,000 nmol/min/mg of protein. Inhibition of aspartoacylase by glycyl-L-aspartate and amino derivatives of D-aspartic acid suggests that the carbon backbone of the substrate is primarily involved in its interaction with the active site and that a blocked amino group is essential for the catalytic activity of aspartoacylase. Biochemical and immunocytochemical studies revealed that aspartoacylase is localized to white matter, whereas the N-acetylaspartic acid concentration is threefold higher in gray matter than in white matter. Our studies so far indicate that aspartoacylase is conserved across species during evolution and suggest a significant role for aspartoacylase and N-acetylaspartic acid in normal brain biology.
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402
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Mao W, Zeng L, Ma Q, Chen Y, Dai Z, Tang P, Guo X, Li D, Su W. [Primary study of iontophoresis of zinc ion in treatment of retinitis pigmentosa]. YAN KE XUE BAO = EYE SCIENCE 1990; 6:88-90. [PMID: 2289582] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
We report here the preliminary effects of zinc iontophoresis in treatment of 26 Rp patients who had decreased zinc serum level or abnormal ratio of serum copper to zinc. Through more than 20 to 30 times of therapy, the vision of 15.38% eyes increased more than "3 lines", 4% eyes increased more than 5 degrees in the visual field, 13.46% eyes improved in dark adaptation threshold (greater than 1.0), the visual functions of the rest eyes were slightly improved or unimproved. The fundus didn't change before & after treatment. There were no changes of ERG in 8 eyes of 4 cases. In addition, the advantages and disadvantages between Zn iontophoresis and Zn compound taken orally, the improvement of vision by direct electric current therapy, the relationship between the metabolism of Zn element and Vit A and influence of Zn over the mechanism of dark adaptation were also briefly discussed.
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403
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Tang P, Juang CL, Harbison GS. Intercalation complex of proflavine with DNA: structure and dynamics by solid-state NMR. Science 1990; 249:70-2. [PMID: 2367853 DOI: 10.1126/science.2367853] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The structure of the complex formed between the intercalating agent proflavine and fibrous native DNA was studied by one- and two-dimensional high-resolution solid-state nuclear magnetic resonance (NMR). Carbon-13-labeled proflavine was used to show that the drug is stacked with the aromatic ring plane perpendicular to the fiber axis and that it is essentially immobile. Natural abundance carbon-13 NMR of the DNA itself shows that proflavine binding does not change the puckering of the deoxyribose ring. However, phosphorus-31 NMR spectra show profound changes in the orientation of the phosphodiester grouping on proflavine binding, with some of the phosphodiesters tilting almost parallel to the helix axis, and a second set almost perpendicular. The first group to the phosphodiesters probably spans the intercalation sites, whereas the tilting of the second set likely compensates for the unwinding of the DNA by the intercalator.
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404
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Santos RA, Tang P, Harbison GS. Determination of the DNA sugar pucker using 13C NMR spectroscopy. Biochemistry 1989; 28:9372-8. [PMID: 2611236 DOI: 10.1021/bi00450a018] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Solid-state 13C NMR spectroscopy of a series of crystalline nucleosides and nucleotides allows direct measurement of the effect of the deoxyribose ring conformation on the carbon chemical shift. It is found that 3'-endo conformers have 3' and 5' chemical shifts significantly (5-10 ppm) upfield of comparable 3'-exo and 2'-endo conformers. The latter two conformers may be distinguished by smaller but still significant differences in the carbon chemical shifts at the C-2' and C-4' positions. High-resolution solid-state NMR of three modifications of fibrous calf thymus DNA shows that these trends are maintained in high-molecular-weight DNA and confirms that the major ring pucker in A-DNA is 3'-endo, while both B-DNA and C-DNA are largely 2'-endo. The data show that 13C NMR spectroscopy is a straightforward and useful probe of DNA ring pucker in both solution and the solid state.
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405
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Maibenco D, Tang P, Shinn R, Hanlon S. Base and conformational specificity of an amine modification of DNA. Biopolymers 1989; 28:549-71. [PMID: 2713452 DOI: 10.1002/bip.360280203] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
We have investigated the site and conformational preference of the reaction of a formaldehyde/amine reagent with DNA. Previous investigations of this laboratory have established that this reagent will react with native DNA, placing a positively charged amine moiety on the duplex that will survive exhaustive dialysis. The resulting adduct is duplex and base stacked in character, possessing B backbone geometry with a higher average winding angle and exhibiting remarkable stability with respect to the A-form, Z-form, or the single-strand denaturated species. In this current investigation, we have found that the stability of the adduct is dramatically reduced if the DNA is converted to mononucleotides, thus obviating the usual approach of nuclease digestion and chromatography for the identification of the modified nucleotides. Using indirect approaches, we have established that the reactive site that survives removal of the equilibrium concentrations of CH2O and amine is the exocyclic amino group of the guanine bases. This conclusion is based on (1) the positive correlation between GC content and the extent of adduct formation under standard reaction conditions (27 degrees C, 0.63M CH2O, 0.007M n-butylamine, pH 7); (2) decreases in the level of substitution of amine in DNA, which has this site blocked by trinitrobenzene modification; and (3) failure of poly(dI-dC) to retain amine upon dialysis. Raman spectra of the derivatized poly(dG-dC) show enhanced 2'-endo B character, with no marked shifts in the position of any of the lines, indicating the absence of any ring structures involving the N7 and the 06 of G. In standard reaction mixtures, other sites may react but this phenomenon appears to be minimal under conditions that do not favor fluctuational opening of base pairs. In the latter case, excess loading of amine on high GC content polymers produces a CD spectrum that is similar to one produced by poly(dA-dT) in the "X"-form [M. Vorlickova, E. Minyat, and J. Kypr (1984) Biopolymers 23, 1-4]. This conformation is lost, however, upon removal of excess reagents by dialysis and cannot be reestablished, in the absence of unbound amine and formaldehyde. The reaction is specific for the B-form of polynucleotides as demonstrated by the failure of poly(dG-m5dC) in the stable Z-form to exhibit substantial reaction. The B-form of this polymer will react readily with the retention of 0.23 moles amine/mole nucleotide under our standard reaction conditions.(ABSTRACT TRUNCATED AT 400 WORDS)
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406
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Tang P, Colflesh DE, Chu B. Temperature effect on fractal structure of silica aggregates. J Colloid Interface Sci 1988. [DOI: 10.1016/0021-9797(88)90124-5] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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407
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Tang P, Sharpe CR, Mohun TJ, Wylie CC. Vimentin expression in oocytes, eggs and early embryos of Xenopus laevis. Development 1988; 103:279-87. [PMID: 3224554 DOI: 10.1242/dev.103.2.279] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Immunocytochemical studies using a monoclonal anti-porcine vimentin antibody reveal a well-organized pattern of staining in Xenopus laevis oocytes, eggs and early embryos. The positions of Xenopus vimentin and desmin in two-dimensional (2D) polyacrylamide gels were first established by immunoblotting of muscle Triton extracts with anti-intermediate filament antibodies (anti-IFA), which cross-react with all intermediate filament proteins (IFPs). The anti-porcine vimentin reacts with vimentin and desmin in muscle 2D immunoblots, but only reacts with one polypeptide in oocyte blots in the position predicted for vimentin (Mr 55 × 10(3), pI 5.6). Using an anti-sense probe derived from a Xenopus vimentin genomic clone in RNase protection assays, we show that expression of vimentin begins in previtellogenic oocytes. The level of expression remains constant throughout oogenesis and in unfertilized eggs. These data suggest that vimentin is expressed in oocytes and eggs. Most interestingly, the immunocytochemical results also show that vimentin is present in the germ plasma of oocytes, eggs and early embryos. It is therefore possible that vimentin has an important role in the formation or behaviour of early germ line cells.
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408
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Tang P, Xu G, Chen XH, Wang YP, Zhang WG, Yuan SL. [Studies of the effect of nickel and nickel compounds on transformation on Syrian hamster embryo cells]. HUA XI YI KE DA XUE XUE BAO = JOURNAL OF WEST CHINA UNIVERSITY OF MEDICAL SCIENCES = HUAXI YIKE DAXUE XUEBAO 1988; 19:150-3. [PMID: 3198095] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
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409
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Tang P, Lo HS. Pentatrichomonas hominis: purine salvage pathway. COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY. B, COMPARATIVE BIOCHEMISTRY 1988; 90:419-25. [PMID: 3409669 DOI: 10.1016/0305-0491(88)90098-3] [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
1. Pentatrichomonas hominis was found incapable of de novo synthesis of purines. 2. Pentatrichomonas hominis can salvage adenine, guanine, hypoxanthine, adenosine, guanosine and inosine, but not xanthine for the synthesis of nucleotides. 3. HPLC tracing of radiolabelled purines or purine nucleosides revealed that adenine, adenosine and hypoxanthine are incorporated into adenine nucleotides and IMP through a similar channel while guanine and guanosine are salvaged into guanine nucleotides via another route. There appears to be no direct interconversion between adenine and guanine nucleotides. Interconversion between AMP and IMP was observed. 4. Assays of purine salvage enzymes revealed that P. hominis possess adenosine kinase; adenosine, guanosine and inosine phosphotransferases; adenosine, guanosine and inosine phosphorylases and AMP deaminase.
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410
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Xu G, Tang P, Wang YP, Chen XH, Zhang WG, Li GG. [Carcinogenic effects on Syrian hamster embryo cells exposed to He-Ne laser in vitro]. HUA XI YI KE DA XUE XUE BAO = JOURNAL OF WEST CHINA UNIVERSITY OF MEDICAL SCIENCES = HUAXI YIKE DAXUE XUEBAO 1987; 18:238-40. [PMID: 3679175] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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411
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Chen CC, Shou L, Hwang LL, Tang P, Tu WC, Lo HS. Persistence of hepatitis B viral antigens in Culex quinquefasciatus. THE SOUTHEAST ASIAN JOURNAL OF TROPICAL MEDICINE AND PUBLIC HEALTH 1987; 18:44-51. [PMID: 3660067] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Culex quinquefasciatus mosquitoes were fed on or inoculated with blood or serum positive for hepatitis B viral antigens and pools of mosquitoes were tested by radioimmunoassay daily for 3 weeks after exposure to detect the viral antigens. Hepatitis B surface antigen (HBsAg) was detectable up to 3 weeks, while hepatitis B e antigen (HBeAg) persisted only for 3 days in mosquitoes after feeding on hepatitis B viral antigens-positive blood. Mosquitoes inoculated with serum were HBsAg-positive for 3 weeks and HBeAg positive for 4 days after inoculation. These results suggest that biological multiplication of hepatitis B virus did not occur in these mosquitoes. The possibility of mechanical transmission of hepatitis B antigens by mosquitoes is discussed.
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412
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DuBridge RB, Tang P, Hsia HC, Leong PM, Miller JH, Calos MP. Analysis of mutation in human cells by using an Epstein-Barr virus shuttle system. Mol Cell Biol 1987; 7:379-87. [PMID: 3031469 PMCID: PMC365079 DOI: 10.1128/mcb.7.1.379-387.1987] [Citation(s) in RCA: 512] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
We developed highly sensitive shuttle vector systems for detection of mutations formed in human cells using autonomously replicating derivatives of Epstein-Barr virus (EBV). EBV vectors carrying the bacterial lacI gene as the target for mutation were established in human cells and later returned to Escherichia coli for rapid detection and analysis of lacI mutations. The majority of the clonal cell lines created by establishment of the lacI-EBV vector show spontaneous LacI- frequencies of less than 10(-5) and are suitable for studies of induced mutation. The ability to isolate clonal lines represents a major advantage of the EBV vectors over transiently replicating shuttle vectors (such as those derived from simian virus 40) for the study of mutation. The DNA sequence changes were determined for 61 lacI mutations induced by exposure of one of the cell lines to N-nitroso-N-methylurea. A total of 33 of 34 lacI nonsense mutations and 26 of 27 missense mutations involve G X C to A X T transitions. These data provide support for the mutational theory of cancer.
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413
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Bai SH, Xu G, Tang P, Chen XH. [A study of antineoplastic activity of DHAQ on human adenocarcinoma cells of lung hepatoma and gastric cancer cells in vitro]. HUA XI YI KE DA XUE XUE BAO = JOURNAL OF WEST CHINA UNIVERSITY OF MEDICAL SCIENCES = HUAXI YIKE DAXUE XUEBAO 1986; 17:284-6. [PMID: 3032765] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
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414
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Tang P, Xu G, Chen XH. [Study on the routine method of a short-term transforming test in mammalian cells in vitro for detecting carcinogens and promotors]. HUA XI YI KE DA XUE XUE BAO = JOURNAL OF WEST CHINA UNIVERSITY OF MEDICAL SCIENCES = HUAXI YIKE DAXUE XUEBAO 1986; 17:185-9. [PMID: 3104196] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
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415
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Wylie CC, Heasman J, Parke JM, Anderton B, Tang P. Cytoskeletal changes during oogenesis and early development of Xenopus laevis. JOURNAL OF CELL SCIENCE. SUPPLEMENT 1986; 5:329-41. [PMID: 3308916 DOI: 10.1242/jcs.1986.supplement_5.21] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The frog oocyte is well known for studies on the control of gene expression, but has been used much less in studies on the cytoskeleton. However, frog oocytes are very large single cells, whose cytoplasmic movements and asymmetries are fundamental to the correct development of the subsequent embryo. One particular example of asymmetrically distributed cytoplasm is germ plasm, thought to be important in the formation of the germ line. Data are presented that show that germ plasm is highly concentrated mass of cytoskeletal elements, which include tubulin, and an intermediate filament protein of molecular weight 55 X 10(3). The distribution of these molecules has been studied during oogenesis and during early post-fertilization development. The implications of these findings are discussed.
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416
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Xu G, Bai SH, Chen XH, Tang P, Li GG. [The injury effect of hematoporphyrin disodium salt of the pig and He-Ne laser to human cells in vitro]. SICHUAN YI XUE YUAN XUE BAO = ACTA ACADEMIAE MEDICINAE SICHUAN 1985; 16:310-13. [PMID: 3837389] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
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417
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Xu G, Bai SH, Tang P, Chen XH, Li GG. [Successful induction of transformation of NIH/3T3 cells in vitro by low energy level He-Ne laser]. SICHUAN YI XUE YUAN XUE BAO = ACTA ACADEMIAE MEDICINAE SICHUAN 1985; 16:19-23. [PMID: 4012585] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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418
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Domen RE, Tang P, Harshman KV. Granular cell myoblastoma of the esophagus after irradiation for carcinoma. South Med J 1979; 72:1207-9. [PMID: 224511 DOI: 10.1097/00007611-197909000-00037] [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: 12/13/2022]
Abstract
Granular cell myoblastoma is an uncommon, usually benign tumor. Only 20 cases are reported in the esophagus. We describe a 65-year-old woman who developed a granular cell myoblastoma of the postericoid esophagus in the area of a squamous cell carcinoma successfully treated with irradiation. To our knowledge, this is the 21st reported case, and the only case occurring in the esophagus after irradiation for primary squamous cell carcinoma.
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419
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Holzbach RT, Marsh M, Tang P. Cholesterolosis: physical-chemical characteristics of human and diet-induced canine lesions. Exp Mol Pathol 1977; 27:324-38. [PMID: 923748 DOI: 10.1016/0014-4800(77)90004-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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420
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Bendezu R, Wieland RG, Tang P, Levine B. Unusual events preceding hyperthyroidism with diffuse goiter. ARCHIVES OF INTERNAL MEDICINE 1977; 137:1023-5. [PMID: 577670] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Two unique patients with hyperthyroidism are presented here. A 48-year-old woman with a family history of Graves' disease was first evaluated and treated for a toxic adenoma with radioactive iodine. Three months later, she was again hyperthyroid, was found to have a diffuse thyromegaly, and was treated with radioactive iodine for the second time. This patient represents, to our knowledge, the first reported case of two sequential forms of endogenous hyperthyroidism. The second patient, a 64-year-old woman, had well-documented hypothyroidism that was presumably primary. She was admitted in thyroid storm and subsequently died. The autopsy disclosed characteristic changes in the thyroid of hyperthyroidism and a normal pituitary gland. The timing of the onset of Graves' disease with hyperthyroidism cannot be accurately determined.
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421
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Wieland RG, Bendezu R, Hallberg MC, Tang P, Webster K. Hormonal evaluation of premature menarche produced by a follicular cyst. Am J Obstet Gynecol 1976; 126:731-3. [PMID: 984153 DOI: 10.1016/0002-9378(76)90532-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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422
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Holzbach RT, Marsh M, Tang P. Liquid crystals in human and diet-induced canine cholesterolosis [proceedings]. REVISTA DE GASTROENTEROLOGIA DE MEXICO 1975; 40:288-9. [PMID: 1236393] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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423
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Strom O, Ollendorff P, Drewsen E, Tang P. Acute deep vein thrombosis treated with porcine plasmin. A double blind trial. THROMBOSIS ET DIATHESIS HAEMORRHAGICA 1974; 32:468-82. [PMID: 4281116] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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424
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Schoenmackers J, Lopez-Campos JL, Tang P, Heinze H. [Degenerative changes in anulus fibrosus and in the neighborhood of the atrioventricular valve with and without calcification. Their influence on valve function, radiolotic differential diagnosis and artificial valve implantation]. Basic Res Cardiol 1973; 68:52-72. [PMID: 4710226 DOI: 10.1007/bf01907656] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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425
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