Biomedical subjects

J L Su

Publications and source records attributed to J L Su.

At least 37 records · Page 2Linked to original sources

PubMed1997

Cloning of a disintegrin metalloproteinase that processes precursor tumour-necrosis factor-alpha.

Tumour-necrosis factor-alpha (TNF-alpha) is a cytokine that contributes to a variety of inflammatory disease states. The protein exists as a membrane-bound precursor of relative molecular mass 26K which can be processed by a TNF-alpha-converting enzyme (TACE), to generate secreted 17K mature TNF-alpha. We have purified TACE and cloned its complementary DNA. TACE is a membrane-bound disintegrin metalloproteinase. Structural comparisons with other disintegrin-containing enzymes indicate that TACE is unique, with noteable sequence identity to MADM, an enzyme implicated in myelin degradation, and to KUZ, a Drosophila homologue of MADM important for neuronal development. The expression of recombinant TACE (rTACE) results in the production of functional enzyme that correctly processes precursor TNF-alpha to the mature form. The rTACE provides a readily available source of enzyme to help in the search for new anti-inflammatory agents that target the final processing stage of TNF-alpha production.

ADAM Proteins↗

PubMed1997

Activation of the nuclear receptor LXR by oxysterols defines a new hormone response pathway.

Accumulation of cholesterol causes both repression of genes controlling cholesterol biosynthesis and cellular uptake and induction of cholesterol 7alpha-hydroxylase, which leads to the removal of cholesterol by increased metabolism to bile acids. Here, we report that LXRalpha and LXRbeta, two orphan members of the nuclear receptor superfamily, are activated by 24(S), 25-epoxycholesterol and 24(S)-hydroxycholesterol at physiologic concentrations. In addition, we have identified an LXR response element in the promoter region of the rat cholesterol 7alpha-hydroxylase gene. Our data provide evidence for a new hormonal signaling pathway that activates transcription in response to oxysterols and suggest that LXRs play a critical role in the regulation of cholesterol homeostasis.

Animals↗

PubMed1997

Rapid development of affinity matured monoclonal antibodies using RIMMS.

Affinity matured murine monoclonal antibody producing cell lines can now be rapidly generated using a novel repetitive, multiple site immunization strategy designated RIMMS. RIMMS capitalizes on rapid hypermutation and affinity maturation events which occur in B cell populations localized within secondary lymphatic tissue early in response to antigenic challenges. A murine myeloma cell line, P3XBcl-2-13, stably transfected with Bcl-2, enhances the outgrowth of hybridomas following somatic fusion with immune lymphocytes isolated from pooled peripheral lymph nodes (PLN) 8-14 days after the initial immunization. Immunizations somatic fusion, screening and isolation of affinity matured IgG secreting monoclonal antibody cell lines occur within a one month time period. By using RIMMS, we have been able to expedite the isolation of affinity matured monoclonal antibodies to numerous antigens, including a drug hapten.

Animals↗

PubMed1997

Neutralizing IGF-1 monoclonal antibody with cross-species reactivity.

We report the generation of a murine IGF-1 monoclonal antibody designated 35I17, which exhibits unique cross-species reactivity. The antibody recognizes recombinant human and rat IGF-1 in ELISA, Western blots, and in an 125I-recombinant human IGF-1 Scintillation Proximity Assay. In addition, 35I17 blocks cell proliferation induced by recombinant human and rat IGF-1, and inhibits cell proliferation induced by sera from human, rat, calf, dog, goat, or mouse. The antibody inhibits rat IGF-1 binding to IGF-1 receptors, and prevents IGF-1-stimulated receptor and IRS-1 phosphorylation in LISN C4 cells, an IGF-1 receptor-transfected cell line. The cross-species and neutralizing properties of 35I17 may be useful in in vitro and in vivo animal studies for elucidating the role of IGF-1 in cancer, rheumatoid arthritis, and other diseases.

3T3 Cells↗

PubMed1997

TNF alpha-mediated inhibition and reversal of adipocyte differentiation is accompanied by suppressed expression of PPARgamma without effects on Pref-1 expression.

Tumor necrosis factor alpha (TNF alpha) is a polypeptide hormone with pleiotropic effects on cellular proliferation and differentiation. To investigate how TNF alpha inhibits and reverses adipocyte differentiation, we studied the expression of two factors involved in the adipocyte differentiation process. Peroxisome proliferator-activated receptor gamma (PPARgamma) is a positive regulator of adipogenesis, whereas preadipocyte factor 1 (Pref-1) inhibits adipocyte differentiation. The expression patterns of both PPARgamma and Pref-1 change during early stages of adipocyte differentiation. Decreased expression of Pref-1 and increased expression of PPARgamma occur 1 day and 2 days, respectively, after 3T3-L1 cells reach confluence. During TNF alpha-mediated inhibition of adipocyte differentiation, PPARgamma messenger RNA (mRNA) expression stays at low levels. In contrast, TNF alpha treatment has no effect on the normal decrease in Pref-1 gene expression that occurs during adipogenesis. We observed that certain cytokine and growth factors [such as TNF alpha, basic fibroblast growth factor, transforming growth factor beta, and protein kinase C-activating agents plus calcium ionophore], when added to differentiated adipocytes, cause rapid down-regulation of PPARgamma mRNA expression with concomitant decrease in adipocyte-specific gene expression but fail to increase Pref-1 mRNA expression. Moreover, addition of TNF alpha to fully differentiated adipocytes results in the rapid disappearance of PPARgamma protein expression and the rapid loss of PPARgamma DNA-binding activity. Therefore, Pref-1 seems to function as a nonreversible molecular checkpoint whose expression is insensitive to TNF alpha-generated signals, whereas PPARgamma expression remains sensitive to TNF alpha at all stages of the adipogenesis program. Our results support the notion that dedifferentiated adipocytes and preadipocytes are not identical, though they share many similar morphological and gene expression patterns.

3T3 Cells↗

PubMed1997

Fluorescent microtiter screening assay for immunocytochemically reactive antibodies.

We have developed a rapid in situ screening procedure that enables prescreening of hundreds of hybridomas in a 96-well format. The procedure involves fluorescence immunostaining of cells cultured in 96-well plates and the use of a fluorescence plate reader to detect reactive antibodies. Positive immunostaining in individual well, as denoted by elevated readings, is then confirmed by fluorescence microscopy. Using the method described here, we have successfully identified monoclonal antibodies that are specific to the nuclear receptor, peroxisome proliferator-activated receptor gamma (PPAR gamma). This assay is readily applicable for screening hybridomas raised against cell surface or intracellular antigens to aid in the initial identification of antibodies reactive in immunocytochemical procedures.

Amino Acid Sequence↗

PubMed1996

Fitting characteristics of 1-day and 14-day Acuvue disposable contact lenses.

The fitting characteristics of 1-day Acuvue disposable soft contact lenses (SCLs) [base curve (BC) 9.0 mm, diameter 14.2 mm] and 14-day Acuvue disposable SCLa (BC 8.8 mm, diameter 14.0 mm) were evaluated and compared with respect to lens centration and post-blink movement in primary gaze and in upgaze. In this double-blind study 25 successful daily wearers of either the 1-day lens or the 14-day lens with the same parameters were randomly fit with three 1-day lenses and three 14-day lenses for a total of 6 lenses per eye. The lene fit was evaluated 5 min after insertion. Lens centration was assessed by measuring temporal, nasal, superior and inferior limbal coverage, and then comparing the net horizontal centration (temporal minus nasal coverage) and the net vertical centration (superior minus inferior coverage) of the 1-day and 14-day lenses. There was no significant difference between the two lenses in terms of temporal, superior, and inferior limbal coverage (p > 0.05). However, the 1-day lens showed statistically more nasal coverage (p < 0.05). No statistically significant difference in movement or in horizontal and vertical differences in centration were found (p > 0.05). Although our findings indicate a subtle statistical difference in fitting characteristics, clinically the two lenses should provide similar fits.

Adult↗

PubMed1995

Monoclonal antibodies against human collagenase and stromelysin.

Mouse monoclonal antibodies against recombinant human fibroblast procollagenase and prostromelysin have been generated and characterized. The epitope-containing domains for the antibodies have been assigned based on their immunoreactivities against recombinant proenzymes, mature enzymes, truncated collagenases, proteolytic fragments of stromelysin, and chimeric molecules constructed from different domains of the two enzymes. These antibodies can be divided into four groups: (1) antibodies that recognize the truncated 19-kDa NH2-terminal collagenase, (2) antibodies that recognize the C-terminal domain of collagenase and stromelysin, (3) antibodies that recognize a 31-kDa NH2-terminal collagenase fragment, and (4) antibodies that recognize the 19-kDa NH2-fragment of stromelysin. The prostromelysin-specific antibody 11N13 is of particular interest; it neutralizes stromelysin activity in a stromelysin peptide substrate assay, with an IC50 value of 75 nM. MAb 11N13 may be useful for in vivo and in vitro studies to validate the roles of stromelysin in tumor cell invasion, metastasis, and connective tissue disorders.

Amino Acid Sequence↗

PubMed1994

Vibration arthrometry of the knee with torn meniscus: a preliminary report.

Although projects using vibration signals generated by the joint to detect joint disorders are still experimental, vibration arthrometry has been shown to be useful in assessing meniscal pathology. A prospective study using vibration arthrometry to diagnose meniscal tears was carried out in 25 consecutive patients with knee injuries. They comprised 20 males and five females with an average age of 34 years. An arthroscopic examination of the injured knee was given to every patient. Six cases of medial meniscal tear, 12 lateral meniscal tear, and two torn discoid menisci were found. The remaining five cases had normal menisci. By correlating the vibration arthrography of the patients to their corresponding arthroscopic findings, 15 were found to be true-positive, five true-negative and five false-negative. There were no false-positive readings. The accuracy, sensitivity and specificity of the vibration arthrometry in diagnosing meniscal tear was 80%, 75% and 100%, respectively. Vibration arthrometry was shown to be a reliable, non-invasive diagnostic tool in diagnosing meniscal tear of the knee.

Adolescent↗

PubMed1992

Amino acid sequence determination of ancrod, the thrombin-like alpha-fibrinogenase from the venom of Akistrodon rhodostoma.

The thrombin-like serine protease and antithrombotic agent, Ancrod, was rapidly purified from the crude venom of Akistrodon rhodostoma by agmatine-Sepharose affinity chromatography followed by MonoQ anion exchange chromatography. N-Terminal sequencing and analysis of overlapping proteolytic fragments of purified Ancrod by automated Edman degradation in combination with tandem mass spectroscopy allowed the determination of the 234 amino acid sequence of the protease. Glycosylation sites at all five canonical N-linked glycosylation sites were inferred from the appearance of blank sequencer cycles in the amino acid sequence and were confirmed by mass spectroscopic analysis of the N-glycanase-treated peptides. Monoclonal antibodies raised against the denatured protein and HF-deglycosylated protein recognized Ancrod on Western blots. Sequence comparison to other thrombin-like serine proteases and reptilian fibrinogenases revealed a number of similarities, most notably the catalytic triad and many conserved cysteine positions.

Amino Acid Sequence↗

PubMed1992

The effect of 3,3-di-pyridyl-methyl-1-phenyl-2-indolinone on the nerve terminal currents of mouse skeletal muscles.

The effects of 3,3-dipyridyl-methyl-1-phenyl-2-indolinone (DPMPI), a new cognition enhancer, on perineural waveforms were assessed on triangularis sterni nerve-muscle preparations in the mouse. The perineural waveforms were recorded with extracellular electrodes placed in the perineural sheaths of motor nerves. At 64.5 microM, DPMPI decreased the fast potassium current of the nerve terminal. The sodium current, calcium currents and calcium-dependent potassium current of the nerve terminal were not affected. At a greater concentration (215 microM), DPMPI decreased all of the components of the waveforms associated with sodium, potassium and calcium currents. It is concluded that DPMPI affects potassium, as well as sodium currents in the nerve terminal. The effect may contribute to its pharmacological actions on synaptic transmission.

Animals↗

PubMed1992

The effect of 3,3-dipyridylmethyl-1-phenyl-2-indolinone on the neuromuscular transmission in the rodent skeletal muscles.

The effects of a cognition enhancer, 3,3-dipyridylmethyl-1-phenyl-2-indolinone (DPMPI) (21.5-645 microM), on neuromuscular transmission were studied electrophysiologically on diaphragms of mouse and rat and the soleus muscle of rat. The drug DPMPI (21.5-645 microM) increased both direct and indirect twitch tension of mouse diaphragm. It also increased (a) the frequency of miniature endplate potentials and (b) the quantal content of endplate potential. However, DPMPI (64.5 microM) affected neither the amplitude of the directly elicited action potential of soleus muscle in the rat nor the magnitude of the resting membrane potential of mouse diaphragm, although DPMPI (215 microM) decreased the amplitude of the compound action potential of phrenic nerve. Based on these results, it is concluded that DPMPI had several effects on neuromuscular transmission, i.e. it (a) facilitated the transmitter releasing process of the motor nerve terminal, (b) decreased the conduction in the phrenic nerve and (c) increased the directly elicited twitch tension.

Action Potentials↗

PubMed1992

Study of the activities of Chinese herb Viscum alniformosanae Part II: The components of conditioned medium produced by Viscum alniformosanae-stimulated mononuclear cells.

The human promyelocytic cell line HL-60 can be induced to monocytoid terminal differentiation by several conditioned media produced by lectin-stimulated mononuclear cells. We reported previously that a 572-conditioned medium (CM) secreted from viscum alniformosanae-stimulated mononuclear cells also had the capacity of inducing HL-60 leukemic cells into mature monocytes. In the present study, we showed that 572-CM did not contain IFN-r, TNF, IL-1 and IL-2 as determined by using ELISA tests. This CM was unable to induce granulocyte-macrophage colony formation. Sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) was used to detect the components of this CM. After running the acrylamide gels, a wide band protein, in the 65-80 kd range was obtained and it was different from those of other mitogens.

Cell Differentiation↗

PubMed1991

Study of the activity of differentiation-induction in a Chinese herb-viscum alniformosanae. Part 1: In vitro induction of differentiation in HL-60 leukemic cell line by conditioned medium secreted from viscum alniformosanae-stimulated mononuclear cells.

A conditioned medium(CM), designated as 572-CMF-, was a Chinese herb viscum alniformosanae (V.A.) stimulated mononuclear cells. This CM has the capacity to induce the promyelocytic cell line HL-60 to differentiate into morphologically and functionally mature monocytoid cells. However, our results on the effect of a combination of 572 conditioned medium and IFN-r, TNF and IL-2 were neither synergistic nor additive. Further investigation of the nature of this conditioned medium remains to be performed.

Cell Differentiation↗

PubMed1991

Lipocortin-I inhibits the synthesis and release of prolactin from human decidual cells: evidence for autocrine/paracrine regulation by lipocortin-I.

The lipocortins are a family of calcium-dependent phospholipid-binding proteins that are induced by glucocorticoids and inhibit phospholipase-A2 activity. To determine whether the lipocortins affect the release of PRL from human decidua, decidual cells from term pregnancies were exposed to recombinant lipocortin-I for 96 h, with medium changes at 24-h intervals. Lipocortin-I (0.01-100 nM) caused a time- and dose-dependent inhibition of PRL release, with a half-maximal effective dose of 50 nM. PRL release was inhibited by 27%, 62%, 93%, and 98% at 24, 48, 72, and 96 h, respectively. The cells exposed to lipocortin-I did not release the enzymes alkaline phosphatase and lactic dehydrogenase, indicating that the inhibitory effect on PRL release was not due to cell death. In addition to inhibiting basal PRL release, lipocortin also completely inhibited the stimulation of PRL release by decidual PRL-releasing factor, a 23.5-kDa protein recently purified from human placenta that stimulates the synthesis and release of decidual, but not pituitary, PRL. Hydrocortisone and dexamethasone (0.1-10 microM) had no effect on PRL release, and arachidonic acid (2-100 microM) inhibited rather than stimulated PRL release. Western blot analysis demonstrated the presence of lipocortin-I in decidual cells and conditioned media. On Northern blot, decidual mRNA hybridized to an oligonucleotide for lipocortin-I. These results strongly suggest that lipocortin-I has an autocrine/paracrine role in regulation of the synthesis and release of PRL from human decidual cells.

Annexins↗

PubMed1989

Hypaque and steroids in the treatment of sudden sensorineural hearing loss.

While the origins of sudden sensorineural hearing loss remain unproven and treatment empirical, the most appropriate therapy remains a matter of controversy. In this paper we have analysed the current forms of treatment, i.e. diatrizoate meglumine, steroids and a vasodilator. The results suggest that although several related factors were shown to indicate a good prognosis regardless of the therapy, none of the currently available regimens produces consistently better results than the spontaneous recovery rate of 65% reported by Mattox & Simmons.

Adult↗

PubMed1989

[Screening of antibodies to human T-cell leukemia virus type I (HTLV-I) in sera of blood donors and comparison of different methods].

Nine hundred and sixty five serum samples of blood donors from the blood bank of Veterans General Hospital Taipei were screened for antibodies to human T-cell leukemia virus type I (HTLV-I) by different methods. Adult T-cell Leukemia cell lines MT-1, MT-2, KH-2 and MT-2 stimulated by phorbol 12-myristate 13-acetate (PMA) were used as target cells in immunofluorescence microscopy (IF) examination with positive rates as 0.20% (2/965), 0.62% (6/965), 0.20% (2/965) and 0.51 (5/965) respectively. In addition to these, enzyme-linked immunosorbent assay (ELISA) gave a 2.59% (25/965) positive rate and particle agglutination (PA) test revealed a positive rate of 0.93% (9/965). The samples positive in IF were also positive in PA and those positive in PA were found positive in ELISA without exceptions. The 25 ELISA positive samples as well as 75 samples randomly chosen from the ELISA negative ones received Western blot (WB) analysis as a confirmation test. Only 3 of these 100 were considered positive in WB, giving a final positive rate of 0.31%, (3/965), and all of them were originally positive in both PA and ELISA. Particle agglutination test as the screening test and Western blot analysis as the confirming one were suggested to be a routine procedure for detecting anti-HTLV-I antibodies in blood banks through detailed comparison and discussion.

Adult↗

PubMed1988

A monoclonal antibody against brain calmodulin-dependent protein kinase type II detects putative conformational changes induced by Ca2+-calmodulin.

A mouse monoclonal IgG1 antibody has been generated against the soluble form of the calmodulin-dependent protein kinase type II. This antibody recognizes both the soluble and cytoskeletal forms of the enzyme, requiring Ca2+ (EC50 = 20 microM) for the interaction. Other divalent cations such as Zn2+, Mn2+, Cd2+, Co2+, and Ni2+ will substitute for Ca2+, while Mg2+ and Ba2+ will not. The antibody reacts with both the alpha- and beta-subunits on Western blots in a similar Ca2+-dependent fashion but with a lower sensitivity. The affinity of the antibody for the kinase is 0.13 nM determined by displacement of 125I Bolton-Hunter-labeled kinase with unlabeled enzyme. A variety of other proteins including tubulin do not compete for antibody binding. The Mr 30,000 catalytic fragment obtained by proteolysis of either the soluble or the cytoskeletal form of the kinase fails to react with the antibody. Calmodulin and antibody reciprocally potentiate each other's interaction with the enzyme. This is illustrated both by direct binding studies and by a decrease of the Kmapp for calmodulin and an increase in the Vmax for the autophosphorylation reaction of the enzyme. The antibody thus appears to recognize and stabilize a conformation of the kinase which favors calmodulin binding although it does not itself activate the kinase in the absence of calmodulin. Since the Mr 30,000 catalytic fragment of the kinase is not immunoreactive, either the antibody combining site of the kinase must be present in the noncatalytic portion of the protein along with the calmodulin binding site or proteolysis interferes with the putative Ca2+-dependent conformational change.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗