A SINE element in the canine D2 dopamine receptor gene and its chromosomal location.
Explore the source record for details and available documents.
Animals↗
Biomedical subjects
C Park
Publications and source records attributed to C Park.
Genetic analyses of Schizosaccharomyces pombe dna2(+) reveal that dna2 plays an essential role in Okazaki fragment metabolism.
In this report, we investigated the phenotypes caused by temperature-sensitive (ts) mutant alleles of dna2(+) of Schizosaccharomyces pombe, a homologue of DNA2 of budding yeast, in an attempt to further define its function in vivo with respect to lagging-strand synthesis during the S-phase of the cell cycle. At the restrictive temperature, dna2 (ts) cells arrested at late S-phase but were unaffected in bulk DNA synthesis. Moreover, they exhibited aberrant mitosis when combined with checkpoint mutations, in keeping with a role for Dna2 in Okazaki fragment maturation. Similarly, spores in which dna2(+) was disrupted duplicated their DNA content during germination and also arrested at late S-phase. Inactivation of dna2(+) led to chromosome fragmentation strikingly similar to that seen when cdc17(+), the DNA ligase I gene, is inactivated. The temperature-dependent lethality of dna2 (ts) mutants was suppressed by overexpression of genes encoding subunits of polymerase delta (cdc1(+) and cdc27(+)), DNA ligase I (cdc17(+)), and Fen-1 (rad2(+)). Each of these gene products plays a role in the elongation or maturation of Okazaki fragments. Moreover, they all interacted with S. pombe Dna2 in a yeast two-hybrid assay, albeit to different extents. On the basis of these results, we conclude that dna2(+) plays a direct role in the Okazaki fragment elongation and maturation. We propose that dna2(+) acts as a central protein to form a complex with other proteins required to coordinate the multienzyme process for Okazaki fragment elongation and maturation.
Adenosine Triphosphatases↗
The tumbling concha-cartilage flap for correction of lop ear.
This article presents a new surgical method that uses tumbling concha-cartilage flaps to correct lop ears. Through a posterior or anterior auricular skin incision, a rectangular or T-shaped cartilage flap is elevated from the concha and tumbled backward. After passing under the postauricular skin, the flap's tip is fixed to the lidded helix or scapha. The recoiling force of the flap's conchal side enables the lidded portion to be in a normal, erect, anatomic position. The method also increases the vertical height of the ear and creates a normally shaped scapha. Sixteen lop ears were corrected using this procedure, with most of them maintaining natural auricular features. Therefore, this method was considered effective for the correction of moderate lop ear deformity.
Adolescent↗
Subfascial expansion and expanded two-flap method for microtia reconstruction.
This article presents an improved two-flap method for microtia reconstruction. In the first stage of this method, a tissue expander is inserted in the mastoid region through a subfascial pocket, after which the overlying fascia and skin are expanded simultaneously with saline infusion for about 5 months. In the second stage, the expanded fascial and skin layers are split and prepared as anteriorly based skin and fascial flaps defined by their vascularity. An erect, three-dimensional, contour-accentuated ear framework fabricated with autogenous rib cartilage is inserted between the two flaps. The anteroauricular surface of the framework is draped with the thin, expanded skin, and the postauricular surface is draped with the thin, expanded fascia and overlying grafted skin. In the third stage, remnant auricular cartilage is removed and the crus helicis, tragus, intertragic notch, conchal floor, and a hollow mimicking the external auditory meatus are shaped. In this study, 146 microtias were reconstructed consecutively using the improved two-flap method. The final results were promising--major complications were minimal and most patients showed consistently favorable aesthetic results. This method married a two-flap procedure with a gradual tissue expansion, conveniently exploiting the advantages of both methods, but without the disadvantages.
Adolescent↗
Dimer formation by a "monomeric" protein.
Dimeric proteins can arise by the swapping of structural domains between monomers. The prevalence of this occurrence is unknown. Ribonuclease A (RNase A) is assumed to be a monomer near physiological conditions. Here, this hypothesis is tested and found to be imprecise. The two histidine residues (His12 and His119) in the active site of RNase A arise from two domains (S-peptide and S-protein) of the protein. The H12A and H119A variants have 10(5)-fold less ribonucleolytic activity than does the wild-type enzyme. Incubating a 1:1 mixture of the H12A and H119A variants at pH 6.5 and 65 degrees C results in a 10(3)-fold increase in ribonucleolytic activity. A large quantity of active dimer can be produced by lyophilizing a 1:1 mixture of the H12A and H119A variants from acetic acid. At pH 6.5 and 65 degrees C, the ribonucleolytic activity of this dimer converges to that of the dimer formed by simply incubating the monomers, as expected for a monomer-dimer equilibrium. The equilibrium dissociation constant for the dimer is near 2 mM at both 65 and 37 degrees C. This value of Kd is only 20-fold greater than the concentration of RNase A in the cow pancreas, suggesting that RNase A dimers exist in vivo. The intrinsic ability of RNase A to form dimers under physiological conditions is consistent with a detailed model for the evolution of homodimeric proteins. Dimers of "monomeric" proteins could be more prevalent than is usually appreciated.
Amino Acid Substitution↗
The EmrR protein represses the Escherichia coli emrRAB multidrug resistance operon by directly binding to its promoter region.
EmrR negatively regulates the transcription of the multidrug resistance pump-encoding operon, emrRAB, by binding to its regulatory region. The binding site spans the promoter and the downstream sequence up to the transcriptional start site of the operon. Structurally unrelated drugs that induce the pump interfere with this binding.
Bacterial Proteins↗
H-NS-Dependent regulation of flagellar synthesis is mediated by a LysR family protein.
H-NS regulates the flagellar master operon (flhDC) and thus is necessary for flagellation of Escherichia coli. However, the molecular mechanism of its regulation has remained unknown. Genetic screening of a transposon insertion abolishing the H-NS effect revealed a previously unidentified gene, named hdfR, encoding a LysR family protein. Binding of purified HdfR to the flhDC promoter was demonstrated by a DNA mobility shift assay, indicating that HdfR is a transcriptional regulator for the flagellar master operon. Furthermore, the expression of the hdfR gene was shown to be negatively regulated by H-NS.
Bacterial Proteins↗
Performance of the ImmunoCard STAT! E. coli O157:H7 test for detection of Escherichia coli O157:H7 in stools.
ImmunoCard STAT! E. coli O157:H7 (Meridian Diagnostics, Inc., Cincinnati, Ohio) is a novel rapid (10-min) test for the presence of Escherichia coli O157:H7 in stools. The test may be performed either directly on stool specimens or on an overnight broth culture of stool. In a multicenter prospective study, 14 of 14 specimens positive by culture for E. coli O157:H7 were positive by the ImmunoCard STAT! O157:H7 test, and there were no false positives from 263 culture-negative specimens. In a retrospective study, the test was positive in 339 (81%) of 417 stored culture-positive specimens and the specificity was 95% (98 of 103 specimens). No false positives were associated with alternate stool pathogens. The ImmunoCard STAT! O157:H7 test has high sensitivity and specificity.
Enzyme-Linked Immunosorbent Assay↗
Towards evidence based emergency medicine: best BETS from the Manchester Royal Infirmary. Activated charcoal in tricyclic antidepressant overdose.
Explore the source record for details and available documents.
Adult↗
Prosthetic ambulation in a paraplegic patient with a transfemoral amputation and radial nerve palsy.
Great importance and caution should be placed on prosthetic fitting for a paraplegic patient with an anesthetic residual limb if functional ambulation is to be achieved. The combination of paraplegia with a transfemoral amputation and radial nerve palsy is a complex injury that makes the rehabilitation process difficult. This article describes a case of L2 paraplegia with a transfemoral amputation and radial nerve palsy on the right side. Following the rehabilitation course, the patient independently walked using a walker at indoor level with a transfemoral prosthesis with ischial containment socket, polycentric knee assembly, endoskeletal shank and multiaxis foot assembly and a knee ankle foot orthosis on the sound side. The difficulties of fitting a functional prosthesis to an insensate limb and the rehabilitation stages leading to functional ambulation are reviewed.
Adult↗
Frequent chromosomal instability but no microsatellite instability in hepatocellular carcinomas.
Microsatellite instability (MSI) phenotype, caused by a deficiency of DNA mismatch repair genes, has been detected in a subset of tumors in the gastrointestinal tract. However, it is not clear how MSI is involved in the tumorigenesis of hepatocellular carcinomas (HCC). Results with HCC are controversial, with positive results published with American and European tumors, but negative with Japanese tumors. We report the absence of MSI in 39 Korean HCCs after analysis with 6 mononucleotide- and over 150 dinucleotide-repeat markers. Only one such dinucleotide-repeat (D2S213) exhibited a reproducible shift in mobility, representing a somatic mutation present in only some of the tumor cells. This may be the result of a spontaneous error of replication due to the intrinsic mutability of these unstable sequences and without any connection to true genomic instability. In support of this interpretation, no frameshift mutations were found at the coding repeats of target genes for the microsatellite mutator phenotype including TGF-betaRII, BAX, hMSH3, and hMSH6. In contrast, we observed frequent allelic losses on chromosomes 4q, 8p, 16q, and 17p by the analysis of dinucleotide repeats (microallelotyping), reflecting a high degree of tumor chromosomal instability, which was significantly associated to the tumor differentiation (p=0.036, Fisher's exact test). These results suggest that, unlike chromosomal instability, widespread MSI plays no role in the development or progression of HCC.
Adolescent↗
Increased expression of vascular endothelial growth factor and angiogenesis in the early stage of multistep hepatocarcinogenesis.
BACKGROUND: Hepatocellular carcinoma (HCC) is known to receive its blood supply principally from the hepatic arteries. Recent studies have reported differences in the vascular supply, especially arterial supply among low- and high-grade dysplastic nodules (DNs) (also referred to as adenomatous hyperplasia and macroregenerative nodules) and HCCs. Increased expression of vascular endothelial growth factor (VEGF) has been reported in HCC. In addition, VEGF may play an important role in the early phases of hepatocarcinogenesis. METHODS: We immunohistochemically stained 7 low-grade DNs, 8 high-grade DNs, 11 early HCCs, 17 small HCCs, and 21 advanced HCCs with antibodies against VEGF, alpha-smooth muscle actin (to identify unpaired arteries, ie, arteries not accompanied by bile ducts, indicative of angiogenesis), CD34 (as a marker of sinusoidal capillarization), and proliferation cell nuclear antigen. RESULTS: Expression of VEGF was found in the hepatocytes and HCC cells. The degree of VEGF expression increased gradually according to the stepwise development of hepatocarcinogenesis. It was higher in high-grade DNs and early HCCs than in low-grade DNs. The hepatocytes and HCC cells adjacent to peliosis and fibrous septa showed stronger VEGF expression. Angiogenesis, unpaired arteries, and sinusoidal capillarization developed from low-grade DNs and gradually increased. It was highest in HCCs. The proliferation cell nuclear antigen labeling indexes of hepatocytes and HCC cells also increased gradually as hepatocarcinogenesis progressed. Small HCCs showed a higher status of neoangiogenesis and cell proliferation activity than advanced HCCs. The degree of VEGF expression was correlated with angiogenesis and cell proliferation activity. CONCLUSION: We conclude that VEGF plays a significant role in angiogenesis, growth, and development of HCC.
Carcinoma, Hepatocellular↗
[A surgical case of acute massive pulmonary embolism associated with a giant free-floating inferior vena cava thrombus].
The risk and mortality of pulmonary embolism is high in patients with free-floating inferior vena cava thrombi. We present a successful surgical case of a 70-year-old male who had acute massive pulmonary embolism associated with a giant free-floating inferior vena cava thrombus extending above the renal veins. Emergent thrombectomy of the pulmonary artery and the inferior vena cava using cardiopulmonary bypass was carried out because he was considered at high risk for fatal recurrent pulmonary embolism. Prophylactical insertion of a Greenfield filter in the inferior vena cava was added. In this report, diagnosis and treatment of inferior vena cava thrombosis is also discussed.
Acute Disease↗
Murine Stat2 is uncharacteristically divergent.
Characterization of the ability of human interferons (IFNs) to rapidly induce genes led to the identification of the first two members of the STAT (signal transducers and activators of transcription) family, Stat1 and Stat2. To study the unique role of this transcription factor in IFN signaling under more physiological conditions, murine Stat2 was isolated and found to be surprisingly divergent. This divergence was most striking in the C-terminal transcriptional activation domain. Studies on murine Stat2 indicate that it functions in IFN signaling. This includes IFN-alpha-dependent activation, nuclear translocation, DNA binding and activation of reporter genes. However, the profound divergence at the C-terminus suggests that murine Stat2 may have evolved to mediate some unique functions as well. To explore this possibility, proteins that interact with the C-termini of murine and human Stat2 were examined. These studies indicate that the murine and human C-termini interact with an overlapping, but distinct set of proteins.
Amino Acid Motifs↗
Direct evidence that the rifamycin polyketide synthase assembles polyketide chains processively.
The assembly of the polyketide backbone of rifamycin B on the type I rifamycin polyketide synthase (PKS), encoded by the rifA-rifE genes, is terminated by the product of the rifF gene, an amide synthase that releases the completed undecaketide as its macrocyclic lactam. Inactivation of rifF gives a rifamycin B nonproducing mutant that still accumulates a series of linear polyketides ranging from the tetra- to a decaketide, also detected in the wild type, demonstrating that the PKS operates in a processive manner. Disruptions of the rifD module 8 and rifE module 9 and module 10 genes also result in accumulation of such linear polyketides as a consequence of premature termination of polyketide assembly. Whereas the tetraketide carries an unmodified aromatic chromophore, the penta- through decaketides have undergone oxidative cyclization to the naphthoquinone, suggesting that this modification occurs during, not after, PKS assembly. The structure of one of the accumulated compounds together with (18)O experiments suggests that this oxidative cyclization produces an 8-hydroxy-7, 8-dihydronaphthoquinone structure that, after the stage of proansamycin X, is dehydrogenated to an 8-hydroxynaphthoquinone.
Actinomycetales↗
Molecular interactions in ribose transport: the binding protein module symmetrically associates with the homodimeric membrane transporter.
The Escherichia coli high-affinity ribose transporter is composed of the periplasmic ribose-binding protein (RBP or RbsB), the membrane component (RbsC) and the ATP-binding protein (RbsA). In order to dissect the molecular interactions initiating the transport process, RbsC suppressors for transport-defective rbsB mutations were isolated. These suppressors are localized in two regions of RbsC, which are allele-specific to N- or C-terminal domain mutations of RBP, suggesting that there are two distinct regions of RbsC, each interacting with one of the two domains of RBP. To demonstrate that these two regions provide a homodimeric binding surface for RBP we constructed a dimeric rbsC in which two genes are joined tandemly from head to tail with the addition of a linker. The dimeric RbsC protein is stable and functional in growth and ribose uptake. By exploiting the allele specificity between the domain-specific mutations and their suppressors, we generated all mutation-suppressor combinations in a single rbsB plus the dimeric rbsC genes. Their phenotypes are consistent with the proposal that the binding protein module interacts symmetrically with homodimeric RbsC. The mode of association proposed here for the ribose transport components could be extended to other ABC transporters with similar structural organizations.
ATP-Binding Cassette Transporters↗
DL-2-Haloacid dehalogenase from Pseudomonas sp. 113 is a new class of dehalogenase catalyzing hydrolytic dehalogenation not involving enzyme-substrate ester intermediate.
DL-2-Haloacid dehalogenase from Pseudomonas sp. 113 (DL-DEX 113) catalyzes the hydrolytic dehalogenation of D- and L-2-haloalkanoic acids, producing the corresponding L- and D-2-hydroxyalkanoic acids, respectively. Every halidohydrolase studied so far (L-2-haloacid dehalogenase, haloalkane dehalogenase, and 4-chlorobenzoyl-CoA dehalogenase) has an active site carboxylate group that attacks the substrate carbon atom bound to the halogen atom, leading to the formation of an ester intermediate. This is subsequently hydrolyzed, resulting in the incorporation of an oxygen atom of the solvent water molecule into the carboxylate group of the enzyme. In the present study, we analyzed the reaction mechanism of DL-DEX 113. When a single turnover reaction of DL-DEX 113 was carried out with a large excess of the enzyme in H(2)(18)O with a 10 times smaller amount of the substrate, either D- or L-2-chloropropionate, the major product was found to be (18)O-labeled lactate by ionspray mass spectrometry. After a multiple turnover reaction in H(2)(18)O, the enzyme was digested with trypsin or lysyl endopeptidase, and the molecular masses of the peptide fragments were measured with an ionspray mass spectrometer. No peptide fragments contained (18)O. These results indicate that the H(2)(18)O of the solvent directly attacks the alpha-carbon of 2-haloalkanoic acid to displace the halogen atom. This is the first example of an enzymatic hydrolytic dehalogenation that proceeds without producing an ester intermediate.
Esters↗
Characterization of UDP-N-acetylglucosamine:alpha-6-d-mannoside beta-1,6-N-acetylglucosaminyltransferase V from a human hepatoma cell line Hep3B.
UDP-N-acetylglucosamine:alpha-6-d-mannoside beta-1, 6-N-acetylglucosaminyltransferase V (GlcNAcT-V) has been purified from cell extracts of the human hepatoma cell line, Hep3B, with 8.7% recovery. The purified enzymes had molecular masses of about 67 and 65 kDa on denaturated and natural conditions, respectively. The values of pI was 5.9. The GlcNAcT-V, when resolved by SDS-PAGE, was positive for Schiff staining, suggesting that the enzyme is glycoprotein. When GlcN,GlcN-biant-PA and UDP-GlcNAc were used as substrates, the enzyme displayed a temperature optimum of around 50 degrees C and optimum an pH of 6.5. The enzyme was stable in response to incubation from pH 4.5 to pH 10.5 at 4 degrees C for 24 h. The presence of UDP-GlcNAc and GlcN,GlcN-bi-PA protected the enzyme from heat inactivation, the extent depending upon the substrate concentration. The activity of the enzyme was stimulated by Mn2+ ion; however, it was inhibited by Fe3+. The enzyme activity was inhibited by another series of NDP-sugars including ADP-, CDP-, GDP-, and TDP-GlcNAc. Studies on the activity of the enzyme toward a variety of pyridylaminated sugars showed that the enzyme is most active toward biantennary (GlcN,GlcN-bi-PA) sugars. The enzymes had apparent Km values of 1.28 and 5.8 mM for GlcN,GlcN-bi-PA and UDP-GlcNAc, respectively. In order to isolate the GlcNAcT-V gene, PCR primers of GNN-1 and GNN-8 were designed and the amplified PCR product carrying the gene was cloned and sequenced. Nucleotide sequence analysis showed a 2220-bp open reading frame encoding a 740-amino-acid protein. This was almost same as the previously reported human sequences, except for some sequence differences in three amino acids. The three amino acid changes were as follows: 375V --> L, 555T --> R, and 592A --> G. These studies represent the detailed characterization of a purified GlcNAcT-V from human hepatoma cell Hep3B.
Base Sequence↗