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Biomedical subjects

M Fung

Publications and source records attributed to M Fung.

At least 37 records · Page 2Linked to original sources
PubMed1994

Diagnostic value of anti-neutrophil cytoplasmic and anti-endothelial cell antibodies in early Kawasaki disease.

OBJECTIVE: To assess the diagnostic potential of anti-neutrophil cytoplasmic antibodies (ANCA) and anti-endothelial cell antibodies (AECA) to distinguish early Kawasaki disease (KD) from febrile diseases resembling KD. DESIGN: Case-control study. SETTING: Tertiary care facility. PATIENTS: Eighteen patients with KD tested within 2 weeks of disease onset and before immune globulin therapy; 20 control children with fever and at least one other KD criterion; 21 children with noninflammatory disorders (patients scheduled for elective surgery, or after trauma). METHODS: We detected ANCA by immunofluorescence and enzyme-linked immunosorbent assay (ELISA), and AECA by a cell-ELISA with fixed human umbilical vein endothelial cells. RESULTS: We found that 7 of 18 patients with KD and 6 of 20 febrile control patients had ANCA (by immunofluorescence or ELISA, p value not significant); 3 of 18 patients with KD and 8 of 20 febrile control patients had AECA (p value not significant). One of three patients with KD who had aneurysms had ANCA; none had AECA. CONCLUSIONS: The ANCA and AECA tests used in this study did not differentiate early KD from other childhood diseases with which it may be confused.

Antibodies, Antineutrophil Cytoplasmic↗
PubMed1993

The Shatin community mental health survey in Hong Kong. II. Major findings.

A large-scale community survey in Shatin, Hong Kong, is presented with a modified two-phase design using flagged and nonflagged subsamples. A modified Self-Reporting Questionnaire and the Diagnostic Interview Schedule (version III) were used as the screening and diagnostic instruments, respectively. Lifetime rates for 19 Diagnostic Interview Schedule/DSM-III diagnoses are presented. The most common diagnoses in Shatin were tobacco dependence, generalized anxiety disorder, alcohol abuse and/or dependence, all phobias, and dysthymic disorder. The male-predominant disorders were tobacco dependence, alcohol abuse/dependence, pathological gambling, and antisocial personality. The female-predominant disorders were generalized anxiety disorder, all phobias, dysthymic disorder, major depressive disorder, obsessive-compulsive disorder, and bereavement.

Adolescent↗
PubMed1992

T-lymphocyte proliferation: tyrosine kinases in interleukin 2 signal transduction.

Interleukin 2 (IL-2)-induced tyrosine phosphorylation appears to play a major role in IL-2-induced cellular proliferation. Several intracellular substrates including the beta chain of the IL-2 receptor complex (IL-2R beta), raf, MAP2 kinase, the regulatory 83 kDa subunit of phosphatidylinositol-3 kinase and S6 kinases are substrates for the IL-2 receptor activated kinase(s). However, none of the identified members of the IL-2 receptor complex exhibits intrinsic tyrosine kinase activity. Therefore, the IL-2R complex must activate intracellular tyrosine kinases. We have demonstrated that specific tyrosine and serine/threonine kinases are coprecipitated with IL-2 receptor constructs that mediate IL-2-induced cell proliferation but not with those that do not. The IL-2-activated tyrosine kinase appears to be associated with a serine and proline rich intracellular domain which is highly conserved between IL-2R beta and the erythropoietin receptor. Although the responsible kinase has not been identified, lck, fyn, fgr, ltk, hck and lyn can be ruled out as obligatory mediators. Using methods to clone tyrosine kinases from T cells, we have identified potential candidate kinases, including several which had not been known to be expressed by T lymphocytes as well as several unique kinases which had not been previously identified in any cell type.

Amino Acid Sequence↗
PubMed1992

Persistent antinuclear antibodies in children without identifiable inflammatory rheumatic or autoimmune disease.

One hundred eight children with musculoskeletal pain considered not to be due to an autoimmune or inflammatory disease had an antinuclear antibody (ANA) test performed. Twenty-four of these children were ANA positive on HEp-2 cell substrate at a screening serum dilution of 1:20. A positive ANA test persisted in 21 of 24 of the patients over a mean time period of 38 months (range 1 to 103 months). No sera from any patient at initial evaluation had anti-DNA antibodies by radioimmunoassay or by indirect immunofluorescence on Crithidia luciliae. One patient recently developed elevated anti-DNA (radioimmunoassay) antibodies but still has a negative assay on C luciliae. Four patients had antibodies to core histones by immunoblotting. None had antibodies to Sm, RNP, Ro (SS-A), or La (SS-B) by counterimmunoelectrophoresis. No patient developed an overt inflammatory or autoimmune disease during a mean follow-up period of 61 months (range 13 to 138 months). A child with musculoskeletal pain and a positive test for ANA, but with no clinical evidence at presentation of inflammatory or autoimmune disease, is at low risk of imminently developing such a disease.

Adolescent↗
PubMed1991

Factors influencing palatoplasty and pharyngeal flap surgery.

An experience of 154 patients undergoing palatoplasty or pharyngeal flap surgery at the University of California, Davis, Medical Center (Sacramento) was retrospectively analyzed. There were 114 palatoplasties, 37 pharyngeal flaps, and three combined palatoplasty and pharyngeal flap procedures performed. Factors that could affect postoperative airway compromise, as well as those thought to influence the number of days hospitalized postoperatively, were evaluated using a three-way analysis of covariance. Some degree of airway compromise occurred in 24 patients. The duration of mouth-gag usage strongly correlated with the incidence and severity of airway compromise. Neither steroids nor antibiotics decreased the incidence of respiratory compromise. However, steroids were associated with a decrease in number of days hospitalized (2.7 days vs 4.2 days). The use of intraoperative antibiotics was also associated with a shorter hospitalization (3.5 vs 4.0 days) and with fewer cases of postoperative fever. The high correlation between significant respiratory compromise and duration of mouth-gag usage, as well as clinical observations, suggest that airway compromise in these patients is due to edema of the tongue and related structures secondary to ischemia.

Airway Obstruction↗
PubMed1990

Independent folding of individual components in hybrid proteins. Evidence that the carboxy-terminal 135 residues of the LexA repressor constitute a single autonomous domain.

Inactivation of the Escherichia coli repressor protein, LexA, takes place through a cleavage reaction which hydrolyzes the Ala84-Gly85 peptide bond near the center of the molecule. The mechanism of cleavage has previously been shown to be an intramolecular reaction stimulated in vitro by elevated pH or by the addition of activated RecA protein. The entire self-cleavage activity of LexA has been found to lie within a 135-residue tryptic fragment extending from Leu68 to the end of the protein at Leu202. Since the activity of self-cleavage is dependent on the proper three-dimensional structure of the protein, we have used it as a probe to investigate the extend of folding autonomy and functional independence of this 135-residue carboxy-terminal domain of LexA by applying a protein fusion approach. A series of twelve different hybrid proteins, containing LexA sequences in a variety of predefined primary structural arrangements, were constructed and evaluated for whether or not self-cleavage activity has been retained. The results revealed that retention or loss of activity is independent of the nature or size of the foreign protein used. Loss of self-cleavage was found to be a function of amino- or carboxy-terminal deletions in the self-cleaving LexA component of the fusion proteins. The present findings, together with the observations of other artificial fusions proteins and the naturally occurring bifunctional and multifunctional proteins, along with the data on helix packing, provide further support for the notion of modular architecture of proteins and suggest that when these autonomous units are fused, they retain their tendency to fold independently of the remainder of the polypeptide to generate physically linked active domains, rather than to fold dependently and yield scrambled structures.

Bacterial Proteins↗
PubMed1990

Interleukin 2-induced tyrosine phosphorylation. Interleukin 2 receptor beta is tyrosine phosphorylated.

Interaction of interleukin 2 (IL2) with its high affinity membrane receptor complex (IL2R) is sufficient to induce proliferation of T lymphocytes. However, the biochemical mechanisms by which IL2 induces this process remain unresolved. The IL2R complex consists of at least two distinct polypeptides that bind IL2, a 75-kDa intermediate affinity subunit (IL2R beta) and a 55-kDa low affinity subunit (IL2R alpha). As indicated by Western blotting with anti-phosphotyrosine-specific antibodies and confirmed by phosphoamino acid analysis, we now demonstrate that interaction of the T cell growth factor interleukin 2 (IL2) with its high affinity receptor on IL2-sensitive human peripheral blood lymphoblasts induces tyrosine phosphorylation of proteins of 92, 80, 78, 70-75, and 57 kDa. IL2 induced tyrosine phosphorylation in YT 2C2 cells which express only the 75-kDa intermediate affinity IL2 binding molecule (IL2R beta) but not in cells which either express only the 55-kDa low affinity IL2 receptor molecule (IL2R alpha) or no IL2-binding sites. Therefore, IL2R beta, in the absence of IL2R alpha, appears sufficient to transduce the transmembrane signal leading to tyrosine phosphorylation. Two different antibodies reactive with phosphotyrosine specifically immunoprecipitated IL2R beta cross-linked to radiolabeled IL2. These findings suggest that IL2R beta is a substrate for the tyrosine kinase which is activated by IL2 binding to its receptor. Thus, like several other growth factor receptors, activation of the IL2R results in an increase in tyrosine phosphorylation with the receptor itself serving as one substrate.

Amino Acids↗
PubMed1990

Site-directed mutagenesis by complementary-strand synthesis using a closing oligonucleotide and double-stranded DNA templates.

An approach for generating structures capable of directing full-length complementary-strand synthesis for double-stranded plasmid DNA is described. The structures are formed following heat denaturation and cooling of linearized plasmid DNA molecules in the presence of what is referred to as a "closing" oligonucleotide. Consisting of a sequence complementary to the free ends of one of the two plasmid strands, the closing oligonucleotide functions as an agent for recircularization of a DNA strand and generation of a primer-circular template structure suitable for polymerase-dependent full-length complementary-strand synthesis and ligation into a covalently closed heteroduplex molecule. When combined with a mutagenic oligonucleotide and uracil-substituted DNA templates, this approach allows site-directed mutagenesis to be performed directly on double-stranded DNA with a mutant formation efficiency of about 50%, a level amenable to rapid screening by DNA sequencing.

Base Sequence↗
PubMed1989

Synthesis and secretion of hepatitis B middle surface antigen by the methylotrophic yeast Hansenula polymorpha.

The methylotrophic yeast, Hansenula polymorpha, has been developed as a host system for the synthesis of heterologous proteins. The middle surface antigen of hepatitis B virus (preS2-HBsAg) has been synthesized under the control of a methanol-regulated promoter derived from the methanol oxidase-encoding gene. The synthesized preS2-HBsAg protein was found to be secreted outside the cell membrane into the periplasm and further excreted into the culture medium following permeabilization of the cell wall with beta-1,3-glucanase (beta Glu). Cell cultures treated with beta Glu were able to continuously synthesize and secrete 22-nm particles of preS2-HBsAg into the medium for several days. The overall yield of antigen from treated cultures was found to be over threefold greater than that of untreated controls. The observation that complex supramolecular structures, such as the 22-nm particles of preS2-HBsAg, can be secreted by H. polymorpha and released into the medium, suggests the potential for these yeasts to be an alternative secretory host.

Cloning, Molecular↗
PubMed1989

Thin-layer chromatographic method for the determination of glycosyltransferase activity.

To survey glycosyltransferase activities and specificities we have developed a TLC method to separate various nucleotide sugars from both high- and low-molecular-weight sugar acceptors. Here, we report details of the procedure and its application for galactosyltransferase and fucosyltransferase detected in mouse spermatogenic cells. The assay method involves sample separation using polyethyleneimine cellulose plastic-backed thin-layer plates, developed in sodium phosphate buffer for 30 min. Nucleotide sugars, including UDP-Gal, GDP-Fuc, CMP-NeuNAc, and GDP-Man, remain at the origin, while both high- and low-molecular-weight sugar acceptors migrate within 2 cm of the solvent front. Assays for galactosyltransferase and fucosyltransferase are linear with time and yield results comparable to other methods such as gel permeation chromatography and micropartitioning filtration. The TLC protocol should be useful for determinations of many different glycosyltransferases.

Animals↗
PubMed1989

Reactivity of antinuclear antibodies with histones and other antigens in juvenile rheumatoid arthritis.

Antinuclear antibodies are found in serum samples from most children with juvenile rheumatoid arthritis (JRA), but the antigenic specificities of these antibodies are not known. Using an immunoblot technique, we found that JRA patients' sera react with a variety of proteins in the nuclei of HEp-2 cells. Antibody to histone H1 was found in 42% of the JRA serum samples. An IgG antibody to a 45-kd protein was found in serum samples from some patients without uveitis, but it was not found in any sample from patients with uveitis. The immunoblot reactivity patterns do not appear to be useful in distinguishing between disease onset types or disease course types in patients with JRA.

Antibodies↗
PubMed1987

Synthesis of 4R- and 4S-tritium labeled NADPH for the determination of the coenzyme stereospecificity of NADPH: protochlorophyllide oxidoreductase.

A rapid and easy method for the production of both the 4R and 4S tritium labeled isomers of either NADH or NADPH has been developed. The method requires the use of only a single labeled compound (D-[1(-3)H] glucose), and two enzymes (glucose dehydrogenase from Bacillus sp. and alcohol dehydrogenase from Thermoanaerobium brockii) which are specific for the pro S and pro R hydrogens, respectively, of either NADH or NADPH. The 4R and 4S tritium labeled isomers of NADPH have been used to determine that NADPH:protochlorophyllide oxidoreductase from etiolated wheat was specific for the pro S hydrogen of NADPH.

Isotope Labeling↗
PubMed1976

Transplant monitoring: patterns of the immune response.

Immune responses, specific to the stored donor tissue, were measured in 26 recipients over 4,000 days. CML positive crossmatches were associated with accelerated rejections (three cases). LDA positive crossmatches resulted in primary non-functioning kidneys (three cases). Post-transplantation. CML (16 hour inculation) was associated with rejection (p equals 0.001), highly predictive of rejection (p equals 0.001), and when positive after rejection treatment, was associated with a failure to respond (p equals 0.005 - 0.01). 51Cr-CDA was also associated with rejection (p equals 0.002). Recovery of these immunologic participants from the explanted kidney substantiated that they were important effector mechanisms in vivo.

Antibodies↗