Search PubMed⌕ Search

Biomedical subjects

C T Wu

Publications and source records attributed to C T Wu.

At least 73 records · Page 4Linked to original sources
PubMed1995

Autosomal dominant familial spastic paraplegia: tight linkage to chromosome 15q.

Autosomal dominant, uncomplicated familial spastic paraplegia (FSP) is a genetically heterogeneous disorder characterized by insidiously progressive lower-extremity spasticity. Recently, a locus on chromosome 14q was shown to be tightly linked with the disorder in one of three families. We performed linkage analysis in a kindred with autosomal dominant uncomplicated FSP. After excluding the chromosome 14q locus, we observed tight linkage of the disorder to a group of markers on chromosome 15q (maximum two-point lod score 9.70; theta = .05). Our results clearly establish the existence of a locus for autosomal dominant FSP in the centromeric region of chromosome 15q. Comparing clinical and genetic features in FSP families linked to chromosome 14q with those linked to chromosome 15q may provide insight into the pathophysiology of this disorder.

Adolescent↗
PubMed1994

Electrokinetic studies of inorganic coated capillaries.

The procedures for the preparation of silica capillaries coated with titanium oxide or aluminum oxide are developed. These inorganic coated capillaries are studied for their applicability in capillary electrophoresis. The points of zero charge are measured as pH 5 and pH 7 for titanium oxide- and aluminum oxide-coated capillaries, respectively. Both titanium oxide and aluminum oxide coatings give better protein separations in comparison to the use of fused-silica capillaries. Separation efficiency of lysozyme as model protein is measured in the range of 20,000 theoretical plates/m of inorganic coated capillaries. However, the hydrophobic interaction between proteins and modified capillary wall possibly contributes to the tailing of observed protein peaks.

Adsorption↗
PubMed1994

Regulatory mechanism of human factor IX gene: protein binding at the Leyden-specific region.

Hemophilia B-Leyden is characterized by the gradual amelioration of bleeding after the onset of puberty. All Leyden phenotype mutations found to date lie within the Leyden-specific region, which spans roughly nt-40 to +20 in the 5' end of the human factor IX gene. With HepG2 cell nuclear extracts, the Leyden-specific region and its immediate neighboring region of the normal factor IX gene showed five DNase I footprints: FP-I (nt +4 to +19), FP-II (nt -16 to -3), FP-III (nt -27 to -19), FP-IV (nt -67 to -49), and FP-V (nt -99 to -77). Protein binding affinities of short oligonucleotides containing sequences of FP-I, FP-II, or FP-III were substantially reduced in the presence of Leyden phenotype mutations in these areas, correlating well with the negative effects of these mutations on factor IX gene expression. A Leyden phenotype mutation at nt -20 (T to A) caused a loss of both footprints FP-III and FP-II but generated a new footprint, FP-III' (nt -34 to -23), partially overlapping with FP-III, indicating mutation-dependent competitive protein binding at these sites. Although the FP-III' area contains an androgen responsive element-like sequence, the nuclear protein that binds at FP-III' is not androgen receptor. The protein was not recognized by anti-androgen receptor antibody and, furthermore, was present not only in liver but also in both androgen receptor-positive and androgen receptor-negative cells in electrophoretic mobility shift assays. The nuclear concentration of this protein increased significantly upon treatment of the HepG2 cells with testosterone. Its binding affinity to an oligonucleotide (-32sub) containing the FP-III' sequence was greatly reduced in the presence of exogenous androgen receptor, suggesting a possible interaction of this protein with androgen receptor. The affinities of both this protein and a protein which binds to FP-III (presumably HNF-4) to -32sub with a mutation at nt -26 were grossly lowered. These findings suggest that the amelioration of hemophilia B-Leyden with a mutation at nt -20 after puberty involves binding of a specific non-androgen receptor nuclear protein at FP-III' and it is able to substitute for the function of a protein bound at FP-III in the normal gene optimally through its elevated interaction with androgen receptor upon a surge of testosterone.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1994

An accurate impression method for implant prosthesis fabrication.

The long-term success of an implant prosthesis depends not only on the development of osseointegration, but also on the maintenance of osseointegration after the prosthetic phase. To achieve this, a passive superstructure must be fabricated. Errors that result from the impression transfer method of implant position during the impression procedures often made it necessary to section and solder metal frameworks repeatedly. This article presents a modified impression technique intended to deal with the problems of more traditional impressions with the aim of achieving a more accurate master cast.

Dental Casting Technique↗
PubMed1992

Effect of direct control of electroosmosis on peptide and protein separations in capillary electrophoresis.

The separations of peptide and protein mixtures in capillary zone electrophoresis (CZE) at various solution conditions were studied with the direct control of electroosmosis. The zeta potential at the aqueous/capillary interface and the resulted electroosmosis in the presence of an electric field were directly controlled by using an additional electric field applied from outside of the capillary. The controlled electroosmotic flow affected the migration time and zone resolution of peptide and protein mixtures. The changes in the magnitude and polarity of the zeta potential caused the various degrees of peptide and protein adsorption onto the capillary through the electrostatic interactions. The separation efficiencies of peptide and protein mixtures were enhanced due to the reduction in peptide and protein adsorption at the capillary wall. The direct manipulations of the separation efficiency and resolution of peptide and protein mixtures in CZE were demonstrated by simply controlling the zeta potential and the electroosmotic flow with the application of an external electric field.

Adrenocorticotropic Hormone↗
PubMed1992

Bizarre parosteal osteochondromatous proliferation of the phalanx: report of a case.

The bizarre parosteal osteochondromatous proliferation of the hand and foot is a benign lesion which occasionally may mimic osteochondromas, chondrosarcomas or osteosarcomas clinically, radiologically and histopathologically. This rare benign entity should be recognized in order to avoid unwarranted destructive therapy. The authors report a case of this disease and discuss the differential diagnosis and the relevant features of this disease entity. A 27-year-old female patient suffered from a painful swelling at the proximal middle phalanx of the right middle finger for five months. The lesion was excised but the residual lesion developed a distinct parosteal growth by radiologic studies one-and-a-half years later. The patient underwent reexcision of the lesion twice. No recurrence was noted 11 months following the last excision. Histopathologically, the first specimen contained bizarre chondrocytes. The recurrent nodular tumors, submitted in the second and third operations, were composed of cancellous bone with fatty marrow and a few marrow elements, and focally capped by cartilage. The adjacent soft tissue contained proliferating fibrous tissue. The osteochondral junctions in the latter two specimens were irregular. We believe that the documentation of this tumor at different stages of development has helped in the further understanding of this rare entity.

Adult↗
PubMed1991

Experimental treatment of L-801 myeloid leukemia mice with low molecular weight natural tumor suppressor of human fetal brain origin.

In human fetal brain tissue there is a low molecular weight suppressor substance which can preferentially suppress murine myeloid leukemic cell (L-801) growth, but with less harmful effects on the growth of normal bone marrow hemopoietic stem cells (CFU-S) and granuloid/macrophage progenitors (CFU-GM) in vitro liquid or agar culture. Mice after inoculation of L-801 cells died within 10-17 days due to development of leukemia. After consecutive injections of the low molecular weight suppressor substance isolated from human fetal brain tissue some of the leukemic mice survived. No pathological changes were observed in the mice which survived longer than 100 days after inoculation of L-801 cells.

Animals↗
PubMed1991

Isolation and characterization of Drosophila multidrug resistance gene homologs.

Mammalian multidrug-resistant cell lines, selected for resistance to a single cytotoxic agent, display cross-resistance to a broad spectrum of structurally and functionally unrelated compounds. These cell lines overproduce a membrane protein, the P-glycoprotein, which is encoded by a member(s) of a multigene family, termed mdr or pgp. The amino acid sequence of the P-glycoprotein predicts an energy-dependent transport protein with homology to a large superfamily of proteins which transport a wide variety of substances. This report describes the isolation and characterization of two Drosophila homologs of the mammalian mdr gene. These homologs, located in chromosomal sections 49EF and 65A, encode proteins that share over 40% amino acid identity to the human and murine mdr P-glycoproteins. Fly strains bearing disruptions in the homolog in section 49EF have been constructed and implicate this gene in conferring colchicine resistance to the organism. This work sets the foundation for the molecular and genetic analysis of mdr homologs in Drosophila melanogaster.

ATP Binding Cassette Transporter, Subfamily B↗
PubMed1991

[Treatment of subgingival crown root fracture: forced eruption--case report].

The conventional treatment methods for a subgingival crown root fracture are (1) extract the residual root and restore with a fixed bridge; (2) crown restoration with a deep subgingival margin; and (3) exposure of the fracture line by a crown lengthening operation and restoration with a crown. However, these methods require reduction of either the tooth structure or the periodontal support. Improvements in endodontic and orthodontic therapy followed Heithersay in 1973 to combine the use of endodontic and orthodontic therapy to manage subgingival crown root fractures--the so-called forced eruption method. This method can save the tooth structure and periodontal tissue. We can now use this method with different appliances to treat subgingival fractures, subgingival caries, subgingival perforations, infrabony pockets, etc. In this report, we present three cases using forced eruption to manage a subgingival fracture and subgingival caries and in the follow-up examination after crown restoration.

Crown Lengthening↗
PubMed1990

Structural and functional basis of the developmental regulation of human coagulation factor IX gene: factor IX Leyden.

Hemophilia B Leyden is characterized by unusual developmental regulation of factor IX synthesis in affected individuals. One family affected with the hemophilia B Leyden phenotype was found to have a specific single-base mutation (G----A) at nucleotide -6 of the factor IX gene. The mutation site was found in a small region of the 5'-untranslated sequence designated the Leyden-specific region (LS region). This region, approximately 40 base pairs in length, contains the unique mutation sites of all the known factor IX Leyden genes (five families) analyzed to date. This fact strongly suggests that the LS region is directly or indirectly involved in the developmental regulation of factor IX biosynthesis. Base changes at nucleotide -20 as well as at nucleotide -6 and deletions of the 3' half of the LS region reduced expression activity of the factor IX gene to approximately 15-31% that of the normal control, as assessed in a cultured cell (HepG2) expression system. The LS region binds at least two proteins. Androgen significantly increased the transcriptional activities of both mutant and normal factor IX genes in a concentration-dependent manner.

Aging↗
PubMed1990

Characterization of the antigenic structure of herpes simplex virus type 1 glycoprotein C through DNA sequence analysis of monoclonal antibody-resistant mutants.

Earlier studies of a group of monoclonal antibody-resistant (mar) mutants of herpes simplex virus type 1 glycoprotein C (gC) operationally defined two distinct antigenic sites on this molecule, each consisting of numerous overlapping epitopes. In this report, we further define epitopes of gC by sequence analysis of the mar mutant gC genes. In 18 mar mutants studied, the mar phenotype was associated with a single nucleotide substitution and a single predicted amino acid change. The mutations were localized to two regions within the coding sequence of the external domain of gC and correlated with the two previously defined antigenic sites. The predicted amino acid substitutions of site I mutants resided between residues Gln-307 and Pro-373, whereas those of site II mutants occurred between amino acids Arg-129 and Glu-247. Of the 12 site II mutations, 9 induced amino acid substitutions within an arginine-rich segment of 8 amino acids extending from residues 143 to 151. The clustering of the majority of substituted residues suggests that they contribute to the structure of the affected sites. Moreover, the patterns of substitutions which affected recognition by antibodies with similar epitope specificities provided evidence that epitope structures are physically linked and overlap within antigenic sites. Of the nine epitopes defined on the basis of mutations, three were located within site I and six were located within site II. Substituted residues affecting the site I epitopes did not overlap substituted residues of site II, supporting our earlier conclusion that sites I and II reside in spatially distinct antigenic domains. A computer analysis of the distribution of charged residues and the predicted secondary structural features of wild-type gC revealed that the two antigenic sites reside within the most hydrophilic regions of the molecule and that the antigenic residues are likely to be organized as beta sheets which loop out from the surface of the molecule. Together, these data and our previous studies support the conclusion that the mar mutations identified by sequence analysis very likely occur within or near the epitope structures themselves. Thus, two highly antigenic regions of gC have now been physically and genetically mapped to well-defined domains of the protein molecule.

Animals↗
PubMed1990

Comparison of the hemopoietic growth factors produced during in vitro culture of murine and human fetal liver cells.

Under the conditions of in vitro liquid culture of murine fetal liver cells, some of the inoculated cells adhere to the flask surface. At optimum culture conditions, those adherent cells can survive and replicate for greater than 6 months in serial passages at intervals of 1 week. A similar adherent layer of cells on the flask surface occurred in a case with human fetal liver cells. These adherent cultured murine and human fetal liver cells can continuously release hemopoietic growth factors into the culture supernatant; among them spleen colony-forming unit (CFU-S) proliferation stimulator, erythrocyte-granulocyte-macrophage colony-stimulating factor (EGM-CSF), burst-promoting factor (BPF), and granulocyte-macrophage colony-stimulating factor (GM-CSF) have been identified. These factors are not only active in triggering resting CFU-S into cell cycling, but also in the proliferation and differentiation of hemopoietic progenitors of different lines.

Animals↗
PubMed1990

Preferential suppression of low molecular weight natural tumor suppressor of human fetal liver origin on the growth of leukemic cells in vitro.

A natural tumor suppressor of human fetal liver origin with low molecular weight (LMW-NTS) was studied. The methanol extract of human fetal liver supernatant (FLS-MeOH), a crude preparation of LMW-NTS, showed preferential suppression on the growth of leukemic cell lines HL-60, L833, WEHI-3, and L1210, but less effect on the growth of normal bone marrow granulocyte-macrophage colony-forming units (CFU-GM) in vitro. Preliminary experiments showed that FLS-MeOH also exhibited preferential suppression on the growth of leukemic colony-forming units (L-CFU) from six patients suffering from acute myeloid leukemia (AML). In combination with a long-term in vitro liquid culture system, FLS-MeOH could be adopted as an effective purging agent in the autologous bone marrow transplantation treatment of myeloid leukemia.

Adult↗
PubMed1989

Homeosis and the interaction of zeste and white in Drosophila.

Transvection effects in Drosophila melanogaster suggest a form of gene modulation that is responsive to the proximity of homologous genes. These effects have been well characterized at bithorax and decapentaplegic, and in the interaction between the zeste and white genes. The mechanistic basis for transvection is not known. As part of a genetic analysis of transvection, a study is being made of a class of mutations defined as modifiers of the eye color resulting from the interaction of zeste and white. This report details the observations that several of these mutations also have homeotic effects.

Animals↗