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M T Sung

Publications and source records attributed to M T Sung.

At least 19 recordsLinked to original sources
PubMed2001

Isolated Rosai-Dorfman disease presenting as peripheral mononeuropathy and clinically mimicking a neurogenic tumor: case report.

BACKGROUND: Rosai-Dorfman disease is a rare idiopathic disorder of proliferative histiocytes affecting the lymph nodes. It usually manifests as bilateral cervical lymphadenopathy and fever with concurrent polyhyperglobulinemia. Cases involving the nervous system are quite rare; most CNS lesions are located intracranially or arise from the spinal dura or leptomeninges. To our knowledge, there has been no previous report of isolated Rosai-Dorfman disease presenting as peripheral mononeuropathy. CASE REPORT: We report a 43-year-old female with isolated extranodal Rosai-Dorfman disease in the medial aspect of the right upper arm, which presented as aberrant ulnar neuropathy caused by a mass encasing the right basilic vein and the medial anteriobrachial cutaneous branch of the right ulnar nerve. Preoperative diagnosis was a neurogenic tumor. The patient underwent excision of the mass, and pathologic examination confirmed the diagnosis of Rosai-Dorfman disease. CONCLUSION: An unusual case of extranodal isolated Rosai-Dorfman disease, presenting as peripheral mononeuropathy, is reported. Clinically, it simulated a neurogenic tumor, extending the etiologic spectrum of entrapment neuropathy of the peripheral nerve.

Adult↗
PubMed2000

Villous adenomas of the urinary tract: report of two cases.

Villous adenomas are rare tumors of the urinary tract. They are morphologically identical to their counterpart in the colon. The histogenesis and malignant potential are uncertain. We report on 2 cases, 1 each in the urethra and bladder. The first is a 57-year-old male who complained of an acute attack of urinary retention. A papillary tumor, measuring 3.0 x 2.0 cm, was found in the prostatic portion of the urethra by cystoscopy, and the tumor was removed transurethrally. The second case, a 33-year-old male, was a victim of chronic pyelonephritis with severe hydronephrosis resulting from a left renal staghorn stone. A papillary tumor was noted on the dome of the urinary bladder. The tumor, measuring 2.0 x 2.0 cm, was resected by transurethral resection. No recurrence or malignant transformation has been found during the follow-up period. The features of morphology, immunohistochemistry, and histochemistry were well studied. Staining by periodic acid-Schiff (PAS) stain, Alcian blue at pH 1.0, and Alcian blue at pH 2.5 were all positive. The carcinoembryonic antigen was strongly positive in the neoplastic glands, especially in the luminal border. We also review the previous literature and discuss the histogenesis, diagnosis, and treatment.

Adenoma, Villous↗
PubMed1997

Phase I trial of PN401, an oral prodrug of uridine, to prevent toxicity from fluorouracil in patients with advanced cancer.

PURPOSE: We performed a phase I study to determine the appropriate dose of PN401, a uridine (URD) prodrug, to use as a rescue agent for fluorouracil (FU) and than to determine the maximum-tolerated dose (MTD) of FU when given with PN401. PATIENTS AND METHODS: Patients with advanced cancer received oral PN401 as either a suspension or a tablet in escalating doses. A pharmacokinetic analysis was performed to determine which dose best achieved a target value of sustained levels of URD > or = 50 mumol/L. In the first phase of the study, all patients received a fixed dose of FU 600 mg/m2 as a rapid intravenous bolus followed by 10 doses of PN401 given at 6-hour intervals. PN401 therapy commenced 24 hours after FU. After determination of the appropriate dose of PN401, a second group of patients received escalating doses of FU with a fixed dose of PN401. RESULTS: Thirty-eight patients with advanced cancer received PN401 and FU. Pharmacokinetic analysis indicated that either 6.6 g of PN401 as an oral suspension or 6 g given in tablet form resulted in high bioavailability of URD, with sustained plasma concentrations greater than 50 mumol/L. In the second phase of the study, FU doses were escalated from 600 to 1,000 mg/m2. FU was given as a rapid intravenous bolus weekly for 6 weeks with a 2-week rest. The MTD of FU given in this fashion with PN401 rescue was 1,000 mg/m2, at which level two of six patients had neutropenic fever. FU at doses of 800 mg/m2 for 6 weeks was well tolerated without significant toxicity when given with PN401 rescue. CONCLUSION: Oral PN401 is well tolerated and total doses of 6 g every 6 hours yield sustained levels of URD in the target range of 50 mumol/L. The MTD of FU with PN401 rescue is 1,000 mg/m2 and the recommended dose for phase II trials is 800 mg/m2 given weekly for 6 weeks with dose escalation. Further studies to define better the appropriate interval for PN401 rescue and the appropriate dose of FU when given with biochemical modulation, such as with leucovorin, are indicated.

Acetates↗
PubMed1983

Molecular processing of adenovirus proteins.

Late in adenovirus infection, a virus-encoded protease processes several viral structural proteins. The maturation cleavages are a prerequisite for full viral infectivity. The peptide fragment removed during processing is located at the amino end of the major core protein VII. The structure of the precursor peptide sequence was determined by both protein and nucleotide sequencing. Two processing events were elucidated. First, during protein biosynthesis, the initiator methionyl residue is removed and the penultimate seryl residue is acetylated. Second, the resulting NH2-terminal 23-residue fragment is removed during virus assembly. The specificity of the viral endoprotease was investigated by isolating and characterizing another viral proprotein precursor, Pro-VI. The propeptide of VI was also found to be extended at the amino end of the molecule. Comparison of the two propeptide sequences at the cleavage site revealed a consensus amino acid sequence of Gly-Gly-Ala. In addition, there is extensive similarity in the precursor sequences of both proteins. The analogous constitution of the precursor fragments in Pro-VI and Pro-VII suggests that a common mechanism is implicated in controlling the reorganization of VI and VII during virion assembly.

Adenoviruses, Human↗
PubMed1983

Gene and protein sequences of adenovirus protein VII, a hybrid basic chromosomal protein.

The sequences of both the gene and the corresponding protein of adenovirus major core protein VII have been determined. The precise location of this gene is between 43.37 and 44.90 map coordinates on the viral genome. Protein VII is 173 residues long and has a molecular weight of 19,258. Detailed analysis of its sequence has revealed four basic domains separated by several predicted alpha helices. It is proposed that intrachain folding of protein VII is driven by hydrophobic interactions of the alpha helices, leaving the basic domains of the protein to interact with DNA phosphates. Protein monomers may further associate with each other in the formation of hexameric nucleosome-like particles. The displacement and replacement of protein VII during the viral infectious cycle in the host cell appears to mimic the biology of nucleoprotamine during the processes of spermatogenesis and fertilization. The presence of a protamine-like domain affirms a hybrid histone/protamine molecular structure for protein VII, although it may resemble the protamine in function.

Adenoviruses, Human↗
PubMed1982

Ultraviolet light induced preferential cross-linking of histone H3 to deoxyribonucleic acid in chromatin and nuclei of chicken erythrocytes.

Histones have been cross-linked to DNA in chicken erythrocyte nuclei and chromatin by using ultraviolet light irradiation at 254 nm. Following irradiation, cross-linked histone-DNA adducts were isolated and purified by hydroxylapatite chromatography, and the DNA component was subjected to acid hydrolysis. Of several hydrolysis techniques investigated, trichloroacetic hydrolysis of the DNA component of the adducts was found to be most effective. Histones isolated from hydrolyzed histone-DNA adducts were characterized by gel electrophoresis and fingerprint analysis. No histone-histone protein adducts were observed. All histone fractions have been shown to cross-link DNA in nuclei or chromatin by utilizing the technique employed, but with different propensities. The order of observed cross-linking, deduced from kinetic experiments, is H1 + H5, H3 greater than H4 greater than H2A much greater than H2B. The preferential binding of the core histone H3, as compared to the other core histones, is discussed in light of recent data concerning histone-DNA interactions and nucleosome structure. The use of the ultraviolet light technique as a conformational probe to study chromatin is also discussed.

Animals↗
PubMed1978

Sites of in vivo phosphorylation of histone H5.

Previous studies have suggested that the phosphorylation and dephosphorylation of histone H5 play an important role in controlling the condensation of avian erythrocyte chromatin. The present work locates in the polypeptide chain the major sites at which H5 is phosphorylated in vivo. The majority of the radioactivity in 32P-labeled H5 is clustered in two regions of the molecule. Nearly 50% of the 32P is found in the amino-terminal N-bromosuccinimide (NBS) peptide (residues 1-28); the remainder is confined to three phosphopeptides arising from the C-terminal half of the molecule (residues 100-200). All phosphopeptides are found in a tryptic digest of monophosphorylated H5, indicating the phosphorylation of a given site is a random event. Automatic Edman degradation of the amino-terminal fragment shows that the radioactivity is equally divided between serines at positions 3 and 7. The C-terminal phosphorylated tryptic peptides share some features with the C-terminal phosphorylation sites in H1. If, as has been postulated, the sites of phosphorylation are in or near DNA combining regions, then H5 may have two DNA combining sites. The location of the phosphorylation sites is discussed in relation to a possible mechanism for controlling chromatin condensation.

Amino Acid Sequence↗
PubMed1977

Use of N-chlorosuccinimide/urea for the selective cleavage of tryptophanyl peptide bonds in proteins. Cytochrome c.

The conditions and utility of the N-chlorosuccinimide/urea (NCS/urea) reagent for the selective cleavage of tryptophanyl peptide bonds in proteins is demonstrated with cytochrome c. At low concentrations of NCS/urea the oxidation of thioether side chains in cytochrome c is the predominant reaction. Methionyl residues are oxidized to sulfoxide and the heme-thioether bridge is partially cleaved. At 10-fold excess of NCS/urea reagent, cleavage of the tryptophanyl peptide bond is optimal at approximately 50% yield in several species of cytochrome c studied. Analytical data on isolated horse cytochrome c peptide fragments demonstrate lack of modification and cleavage at tyrosyl and histidyl residues. However, at high concentrations of NCS/urea reagent (30-fold) unexpected conversions of methionine to sulfone and cysteine to cysteic acid in intact proteins are observed. This is in contradistinction to the absence of sulfone in NCS/urea-reacted amino acid mixtures. The mechanisms of halogenation and cleavage by N-bromosuccinimide, N-iodosuccinimide, and N-chlorosuccinimide are discussed. It is porposed that the selectivity with respect to halogenation by N-chlorosuccinimide is due to the insignificant participation of molecular chlorine in the NCS/urea reaction. A mechanism of halogenation and cleavage by NCS at tryptophan is also offered.

Amino Acids↗
PubMed1977

Metabolism of histones in avian erythroid cells.

The synthesis and enzymatic modifications of histones by phosphorylation, acetylation, and methylation during erythroid cell maturation have been studied. All newly synthesized histones, H1, H5, H2a, h2b, h3, and H4 undergo phosphorylation; histones H2a, H2b, H3, and H4, are acetylated and histones H3 and H4 are methylated. This type of histone metabolism is common to all dividing cells and therefore may be related to the assembly of histones into chromatin subunits. In the nondividing reticulocytes, the synthesis of histone H5 continues, while all the other histones show negligible incorporation of [3H]amino acids. Furthermore, the reticulocytes show a unique pattern of enzymatic modification: phosphorylation of histone H2b, acetylation of histones H2a, H2b, H3, and H4, and methylation of histones H3 and H4. These "differentiation-linked" modifications are not dependent on histone synthesis, nor related to RNA synthesis, but may be related to the reorganization of chromatin in preparation for genomic inactivation.

Acetates↗
PubMed1977

Phosphorylation and dephosphorylation of histone (V (H5): controlled condensation of avian erythrocyte chromatin. Appendix: Phosphorylation and dephosphorylation of histone H5. II. Circular dichroic studies.

During avian erythropoiesis, the blast cells of the bone marrow mature into polychromatic erythrocytes (late stages knwon as reticulocytes) and then into mature red blood cells. When chickens are made anemic, the proportion of immature cells in the anemic bone marrow increases dramatically. The level of the lysine-rich histones. H1 and H5, has been found to be constant in the blood and bone marrow of normal and anemic chickens. This implies that H5 replaces H1 quantitatively. Urea-aluminum-lactate starch gel electrophoresis of H5 from these sources show that the degree of phosphorylation of H5 is proportional to the number of immature cells. About 70% of the H5 from the most immature bone marrow is phosphorylated, while 50% of the H5 from anemic blood is phosphorylated and H5 in normal blood is almost completely devoid of phosphate. When immature cells of the anemia bone marrow are incubated in the presence of inorganic 32P and [3H]lysine and [3H]arginine, extensive 32P incorporation is found in the phospho species. A minimum of nine phosphorylated components have been demonstrated by starch gel electrophoresis. The incorporation of 3H is time dependent. After 1.5 h of labeling, 3H is found in H5 containing 0, 1, 2, and 3 phosphates. tthe combined data suggest that newly synthesized H5 becomes progressively phosphorylated and that at the terminal stage of development, the phosphorylated H5 is completely dephosphorylated. These events may be important in controlling the timing of chromatin condensation.

Anemia↗
PubMed1976

Isolation and characterization of an extremely basic protein from adenovirus type 5.

By starch-gel electrophoresis and a staining method that is highly sensitive for argininyl residues, adenovirus type 5 was found to contain two minor basic polypeptides of extreme cathodic mobility in addition to the two known core proteins. The fastest-migrating polypeptide, named mu protein, and the second fastest polypeptide are found in adenovirions and virus-infected KB cells but not in top components or in uninfected cells. The top components and infected cells contain an additional basic polypeptide, presumably P-VII, that migrates slightly slower than polypeptide VII. None of the basic polypeptides of adenovirions was electrophoretically identical to the host histone. The basic proteins of adenovirions were purified by urea phosphocellulose column chromatography and characterized by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The two minor basic core proteins, mu and another component, have similar mobilities in sodium dodecyl sulfate-polyacrylamide gels as a complex of polypeptides X-XII. After further purification on a Sephadex G-75 column, the mu protein was found to have a molecular weight of about 4,000. Amino acid analysis showed that the mu protein lacks tryptophan and 69% of the total amino acid residues are basic, that is, 54% arginine, 13% histidine, and 2% lysine. Only eight amino acids seem to contribute to make the mu polypeptide. There are 125 copies of the mu polypeptide per 1,000 copies of polypeptide VII in a virion.

Adenoviridae↗
PubMed1972

Molecular complexes of methoxyindoles with 1,3,5-trinitrobenzene and tetracyanoethylene.

Association constants for 1:1 molecular complexes formed between 1,3,5-trinitrobenzene and various methoxy-substituted indoles have been determined by chemical-shift measurements in their nuclear magnetic resonance spectra. The values of association constants for the molecular complexes are comparable to those obtained by optical spectroscopy. The effect on the association constants and relative chemical shifts of the acceptor protons of the pure complexes of various donors is considered. The association constants and relative chemical shifts of the complexes determined by different protons on the nidoles in the presence of an excess of 1,3,5-trinitrobenzene are different. The possible structure of the complexes is discussed. The molecular complexes between tetracyanoethylene and various methoxyindoles have also been studied.

Journal Article↗