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Biomedical subjects

S W Wong

Publications and source records attributed to S W Wong.

At least 19 recordsLinked to original sources
PubMed1992

Characterization of nuclear protein binding to the interferon-gamma promoter in quiescent and activated human T cells.

Nuclear protein binding to the human interferon-gamma (IFN-gamma) promoter was investigated to determine the structural basis for the control of gene expression during T cell activation. DNase I footprinting of gel-shift complexes demonstrated that proteins bind to two downstream (-124 to -114 and -36 to -30) and one upstream (-534 to -486) element in the IFN-gamma gene promoter. Treatment of human peripheral blood lymphocytes or continuous T cell tumors with phorbol 12-myristate 13-acetate (PMA) plus phytohemagglutinin or calcium ionophore results in a pattern of response that is similar when using either the upstream or downstream elements. Upon induction of T cells, the lower mobility gel-shift band disappears. Yet the equivalent band which is also present in non-T cells is unperturbed after PMA + calcium ionophore treatment. The higher mobility band which is modified upon induction is restricted to the T cell lineage. Upstream and downstream elements share similar protein-binding motifs as indicated by the homology of footprinted sequences, the similarity of protein-binding patterns, and the ability of these elements to compete against each other in gel-shift protein-binding assays. Protein binding to the downstream elements appears to be interactive, since both sites are required for complex formation. When either of the two downstream elements is disrupted by site-directed mutagenesis, the higher mobility gel-shift band is diminished by an amount that is consistent with the reduction in reporter (chloramphenicol acetyltransferase) gene expression. Therefore, proteins in the ubiquitous gel-shift band appear to be associated with the inactive state of IFN-gamma, while the modified band is closely associated with the positive regulation of IFN-gamma gene expression.

Base Sequence↗
PubMed1992

Sudden death in children due to mesenteric defect and mesenteric cyst.

Two cases of sudden death in young female children due to small intestinal volvulus are reported, which involved a mesenteric defect and a mesenteric cyst. Death due to small intestinal volvulus is uncommon, especially when complicated by either a mesenteric defect or cyst.

Child, Preschool↗
PubMed1992

[CT guided direct intervention chemotherapy of lung cancer].

The results of 4 pathologically proven advanced lung cancer patients treated by CT guided percutaneous intubation of chemotherapeutic agent into the tumor are reported. Multidrug chemotherapy using mitomycin, cisplatin, cyclophosphamide or 5-Fu was given in a total of 11 treatments. All patients had symptomatic improvement with tumor reduction. There was no incidence of pneumothorax and other side reactions were mild. The authors believe that direct intervention chemotherapy of lung cancer is an effective and safe treatment of choice in advanced cases.

Adenocarcinoma↗
PubMed1991

Elements in the transcriptional regulatory region flanking herpes simplex virus type 1 oriS stimulate origin function.

Like other DNA-containing viruses, the three origins of herpes simplex virus type 1 (HSV-1) DNA replication are flanked by sequences containing transcriptional regulatory elements. In a transient plasmid replication assay, deletion of sequences comprising the transcriptional regulatory elements of ICP4 and ICP22/47, which flank oriS, resulted in a greater than 80-fold decrease in origin function compared with a plasmid, pOS-822, which retains these sequences. In an effort to identify specific cis-acting elements responsible for this effect, we conducted systematic deletion analysis of the flanking region with plasmid pOS-822 and tested the resulting mutant plasmids for origin function. Stimulation by cis-acting elements was shown to be both distance and orientation dependent, as changes in either parameter resulted in a decrease in oriS function. Additional evidence for the stimulatory effect of flanking sequences on origin function was demonstrated by replacement of these sequences with the cytomegalovirus immediate-early promoter, resulting in nearly wild-type levels of oriS function. In competition experiments, cotransfection of cells with the test plasmid, pOS-822, and increasing molar concentrations of a competitor plasmid which contained the ICP4 and ICP22/47 transcriptional regulatory regions but lacked core origin sequences resulted in a significant reduction in the replication efficiency of pOS-822, demonstrating that factors which bind specifically to the oriS-flanking sequences are likely involved as auxiliary proteins in oriS function. Together, these studies demonstrate that trans-acting factors and the sites to which they bind play a critical role in the efficiency of HSV-1 DNA replication from oriS in transient-replication assays.

Animals↗
PubMed1989

DNA polymerases alpha and delta are immunologically and structurally distinct.

The relationship between DNA polymerases alpha and delta are evaluated immunologically by monoclonal antibody specifically against DNA polymerase alpha and murine polyclonal antiserum against calf thymus DNA polymerase delta. DNA polymerases alpha and delta are found to be immunologically distinct. The structural relationship between the proliferating cell nuclear antigen (PCNA)-dependent calf DNA polymerase delta and DNA polymerase alpha from human and calf was analyzed by two-dimensional tryptic peptide mapping of the catalytic polypeptides. The results demonstrate that the catalytic polypeptides of the PCNA-dependent calf polymerase delta and DNA polymerase alpha are distinct, unrelated, and do not share any common structural determinants. The immunological and structural relationship between a recently identified PCNA-independent form of DNA polymerase delta from HeLa cells was also assessed. This PCNA-independent human polymerase delta was found to be immunologically unrelated to human polymerase alpha but to share some immunological and structural determinants with the PCNA-dependent calf thymus polymerase delta.

Antibodies↗
PubMed1989

Human DNA polymerase alpha: predicted functional domains and relationships with viral DNA polymerases.

The primary sequence of human DNA polymerase alpha deduced from the full-length cDNA contains regions of striking similarity to sequences in replicative DNA polymerases from Escherichia coli phages PRD1 and T4, Bacillus phage phi 19, yeast DNA polymerase I, yeast linear plasmid pGKL1, maize S1 mitochondrial DNA, herpes family viruses, vaccinia virus, and adenovirus. The conservation of these homologous regions across this vast phylogenetic expanse indicates that these prokaryotic and eukaryotic DNA polymerases may all have evolved from a common primordial gene. Based on the sequence analysis and genetic results from yeast and herpes simplex virus studies, these consensus sequences are suggested to define potential sites that subserve essential roles in the DNA polymerase reaction. Two of these conserved regions appear to participate directly in the active site required for substrate deoxynucleotide interaction. One region toward the carboxyl-terminus has the potential to be the DNA interacting domain, whereas a potential DNA primase interaction domain is predicted toward the amino-terminus. The provisional assignment of these domains can be used to identify unique or dissimilar features of functionally homologous catalytic sites in viral DNA polymerases of pathogenetic significance and thereby serve to guide more rational antiviral drug design.

Amino Acid Sequence↗
PubMed1989

Xanthogranulomatous cholecystitis. A clinical and pathologic study of twelve cases.

Xanthogranulomatous cholecystitis often presents as a severe chronic cholecystitis associated with abdominal pain, fever, and leukocytosis. Gallstones are present in most cases. At operation, there are adhesions to surrounding tissues, and sometimes a mass is found, mimicking tumor of the gallbladder. The gross and microscopic appearances are characteristic with multiple intramural nodules composed of foamy histiocytes and inflammatory cells. Cholesterol contents of these nodules are high. Involvement of the Rokitansky-Aschoff sinuses with liberation of bile lipids into the adjacent tissue is implicated in the pathogenesis of this lesion.

Adult↗
PubMed1988

Human DNA polymerase alpha gene expression is cell proliferation dependent and its primary structure is similar to both prokaryotic and eukaryotic replicative DNA polymerases.

We have isolated cDNA clones encoding the human DNA polymerase alpha catalytic polypeptide. Studies of the human DNA polymerase alpha steady-state mRNA levels in quiescent cells stimulated to proliferate, or normal cells compared to transformed cells, demonstrate that the polymerase alpha mRNA, like its enzymatic activity and de novo protein synthesis, positively correlates with cell proliferation and transformation. Analysis of the deduced 1462-amino-acid sequence reveals six regions of striking similarity to yeast DNA polymerase I and DNA polymerases of bacteriophages T4 and phi 29, herpes family viruses, vaccinia virus and adenovirus. Three of these conserved regions appear to comprise the functional active site required for deoxynucleotide interaction. Two putative DNA interacting domains are also identified.

Amino Acid Sequence↗
PubMed1988

Gene expression of human DNA polymerase alpha during cell proliferation and the cell cycle.

We studied the expression of the human DNA polymerase alpha gene during cell proliferation, during cell progression through the cell cycle, and in transformed cells compared with normal cells. During the activation of quiescent cells (G0 phase) to proliferate (G1/S phases), the steady-state mRNA levels, rate of synthesis of nascent polymerase protein, and enzymatic activity in vitro exhibited a substantial and concordant increase prior to the peak of in vivo DNA synthesis. In transformed cells, the respective values were amplified greater than 10-fold. In actively growing cells separated into discrete stages of the cell cycle by counterflow elutriation or by mitotic shakeoff, levels of steady-state transcripts, translation rates, and enzymatic activities of polymerase alpha were constitutively and concordantly expressed at all stages of the cell cycle, with only a moderate elevation prior to the S phase and a slight decline in the G2 phase. These findings support the conclusion that the regulation of human DNA polymerase alpha gene expression is at the transcriptional level and strongly suggest that the regulatory mechanisms that are operative during the entrance of a cell into the mitotic cycle are fundamentally different from those that modulate polymerase alpha expression in continuously cycling cells.

Cell Cycle↗
PubMed1987

Serum beta-human chorionic gonadotropin levels relate poorly with the size of a tubal pregnancy.

Ectopic implantation usually begins with relatively normal growth of trophoblast and serum beta-hCG progression. However, the trophoblast eventually erodes into vessels and a variable degree of bleeding and hematoma compromises its growth. The serum beta-hCG level then usually begins to demonstrate some degree of abnormal progression. For our patients, the length of the ectopic pregnancy varied widely, depending mainly on when the individual patient chose to seek medical treatment. Infertility patients followed from the moment of conception would thus be expected to show a better correlation between early beta-hCG levels and the size of the tubal pregnancy. Preconditions for the operative laparoscopic management of a tubal pregnancy usually include that the tube be unruptured, less than 3 cm in diameter, and readily accessible via the laparoscopic approach. Ackerman et al. suggested there was a general correlation between the serum beta-hCG level and tubal rupture, and the present data demonstrate an overall positive correlation between the size of the tubal pregnancy and the serum level. However, the range of levels is so broad for any given size of mass or tubal status that this correlation is not meaningful clinically. A reliable method to determine the size and status of a tubal pregnancy before laparoscopy would be valuable. Unfortunately, we did not find the preoperative serum beta-hCG level to be useful for making this prediction.

Chorionic Gonadotropin↗
PubMed1986

Structural and enzymological characterization of immunoaffinity-purified DNA polymerase alpha.DNA primase complex from KB cells.

We describe the polypeptide structure and some of the catalytic properties of a DNA polymerase alpha.DNA primase complex that can be prepared from KB cells by immunoaffinity purification. The procedure is based on monoclonal antibodies that were raised against a biochemically purified, catalytically active core protomer of the polymerase. In all respects tested, the basic mechanism of substrate recognition and binding by the immunoaffinity-purified polymerase is qualitatively identical to that of the core protomer. The immunoaffinity-purified KB cell polymerase alpha X DNA primase is structurally complex. On the basis of extensive immunochemical analyses with five independent monoclonal antibodies, three of which are potent neutralizers of polymerase alpha activity, peptide mapping studies, and the application of a sensitive immunoassay that permits detection of polymerase alpha antigens in crude cell lysates, we have established that the principal form of catalytically active DNA polymerase alpha in KB cells is a phosphoprotein with a molecular mass of 180 kilodaltons. This protein is stable in vivo, with an estimated half-life of greater than or equal to 15 h. In contrast, the polypeptide is extremely fragile in vitro and generates partial degradation products of p165, p140, and p125 that explain the "microheterogeneity" typically exhibited by polymerase alpha peptides in denaturing polyacrylamide gels. In addition to the catalytically active polymerase alpha polypeptide(s), the immunopurified enzyme fraction typically contains three other proteins, p77, p55, and p49, the functions of which have not yet been established. These proteins do not display polymerase alpha epitopes and have been shown by peptide mapping to be independent species that are unrelated either to the large polymerase peptides or to one another. The polypeptide p77 is also a phosphoprotein, and in both p180 and p77 the phosphorylated amino acids are exclusively serine and threonine.

Antibodies, Monoclonal↗
PubMed1985

Evaluation of the new generation of urinary pregnancy tests.

Five new enzyme-linked urinary pregnancy tests were compared with the older hemagglutination assay. Urine came from 60 patients with a simultaneous serum beta-subunit of human chorionic gonadotropin determination. The new enzyme-linked kits have improved sensitivity with fewer false positive results than the older system. Some kits are clearly quicker and simpler to use than others.

Antibodies, Monoclonal↗
PubMed1984

Paths to psychiatric care in Hong Kong.

The pattern of psychiatric consultation in Hong Kong is examined among 226 patients at a public outpatient clinic and 56 patients at a private psychiatric clinic. The approach to psychiatric services is marked by lengthy delay during which patients get help from their family members or close friends. Arrival at the present psychiatric clinic was diverted through other medical resources, primarily Western-style medical services, and to some extent, traditional Chinese medicine. Individual routes were diverse, characterized by frequent switches among resources especially in the private sector. The nature of the patients' presenting complaints as well as the conceptualization of their initial complaints were multi-faceted, including both psychological and somatic factors. The overall consultation pattern of patients in Hong Kong is compared with other studies on Chinese and Western patients. Questions are raised for further analysis.

Adult↗
PubMed1984

Cancer cellulitis.

We have described a case of inflammatory carcinoma involving the skin of the inguinal region in a man with rectal carcinoma. This type of metastatic lesion is most often associated with carcinoma of the breast, but may also be a manifestation of lung, pancreatic, or gastrointestinal neoplasms. The diagnosis should be suspected when a patient with cellulitis is afebrile and has a normal white blood cell count. An additional clue is that the leading edge of the cellulitis may be raised as in erysipelas. Empiric antibiotic treatment is recommended until the diagnosis is confirmed by punch biopsy and the culture results are known.

Aged↗
PubMed1983

Frequency of Entamoeba gingivalis in human gingival scrapings.

A survey was made of gingival scrapings stained by the Papanicolaou method to assess the occurrence of Entamoeba gingivalis, a nonpathogenic-oral amoeba. Positive findings were recorded in 59% of 113 dental patients, and 32% of 96 healthy controls. These figures showed no significant changes during the last 20 years when compared with data published in 1960 and 1963. The existence of E. gingivalis and its rare appearance in the sputum should be known to cytologists because of the morphologic resemblance to Entamoeba histolytica, a pathogenic amoeba. Morphologic features are described to differentiate E. gingivalis from similar structures found in sputum.

Entamoeba↗