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Xiao-Feng Yang

Publications and source records attributed to Xiao-Feng Yang.

At least 19 recordsLinked to original sources
PubMed2026

Exploration of the antibacterial function of the Eutherian LEG1s.

Liver-enriched gene 1 (LEG1) encodes a novel protein family whose functions are not fully explored. LEG1 was first reported and characterized in zebrafish, where it encodes secreted proteins involved in liver development. In contrast, mammalian LEG1s exhibit a different expression pattern. The platypus monotreme lactation protein (platMLP) was uncovered in milk with antibacterial function. Studies in mouse and pig have shown that LEG1s are specifically expressed in the salivary glands; however, their function remains unclear. Evolutionarily, LEG1s are present in vertebrates and form three major clades, LEG1a, LEG1b, and LEG1c. Only a few invertebrates, protists, and bacteria retain LEG1 homologs, making the evolutionary origin of LEG1 obscure. In the current study, we conducted a thorough exploration of prokaryotic reference genomes and found that LEG1 predominantly exists in Actinomycetota. Given that Actinomycetota are well known for producing antibacterial compounds, and that platMLP can inhibit the growth of certain bacteria, we hypothesized that LEG1 is a conserved antibacterial protein. Recombinant LEG1s from each of the three clades were then purified and subjected to antibacterial tests, which showed that pig LEG1c and platMLP have divergent antibacterial activities. These findings support the hypothesis that the antibacterial function of LEG1 is conserved in eutherians but has undergone functional diversification following gene duplication events.

Animals↗
PubMed2006

Chemiluminescence determination of sodium new houttuyfonate in pharmaceutical preparations based on tween 80-rhodamine B system.

Strong chemiluminescence (CL) emission was observed when sodium new houttuyfonate (SNH) was mixed with Tween 80 in sulfuric acid medium in the presence of rhodamine B. Base on this phenomenon, a sensitive flow injection-CL method for the determination of SNH was developed. Under the optimum conditions, the CL emission is linearly with SNH concentration in the range 8.0-4000 ng mL(-1), with a detection limit of 2.7 ng mL(-1) (3sigma). As a preliminary application, the proposed method was successfully applied to the determination of SNH in pharmaceutical preparations. The possible CL mechanism was also discussed in this paper.

Alkanes↗
PubMed2006

A fluorescein-based fluorogenic probe for fluoride ion based on the fluoride-induced cleavage of tert-butyldimethylsilyl ether.

A highly sensitive and selective fluorogenic probe for fluoride ion, fluorescein di-tert-butyldimethylsilyl ether (FTBS), was designed and synthesized. FTBS was a colorless, non-fluorescent compound and was synthesized via the one-step reaction of fluorescein with tert-butyldimethylsilyl chloride. Upon incubation with fluoride ion in DMF-water solution (7 : 3, V/V), the Si-O bond of FTBS was cleaved, causing a large increase in fluorescence intensity and thereby allowing a selective detection of fluoride ion. The fluorescence increase is linearly with fluoride concentration in the range 0.1-2.0 mumol L(-1) with a detection limit of 0.041 mumol L(-1) (3sigma). The excellent selective signaling behavior of the proposed probe was found to originate from the high affinity of silicon toward fluoride ion. The method has been successfully applied to the fluoride determination in multi-trace elements injection and toothpaste samples, and the results are agreed well with those obtained by the fluoride-ion selective electrode method.

Fluorescein↗
PubMed2006

Novel tumor antigens elicit anti-tumor humoral immune reactions in a subset of patients with polycythemia vera.

We attempted to determine whether the immune reactions elicited by aberrantly expressed testis antigens contribute to the beneficial responses to interferon (IFN)-alpha therapy and other therapies in patients with polycythemia vera (PV). We screened a human testis cDNA library using SEREX (serological analysis of tumor antigens by screening an expression cDNA library with sera from three patients with PV who had undergone IFN-alpha-induced or other therapeutics-induced remission). We identified two novel PV associated tumor antigens, PV65 (eIF-2alpha) and PV13 (protamine 2). These 2 antigens elicited IgG antibody reactions in a subset of PV patients but not in healthy donors, suggesting that they are authentic tumor antigens. Increased phosphorylation of PV65 in response to stimulation of IFN-alpha, and upregulation of PV13 in tumor cells might enhance their abilities in elicitation of immune reactions in patients. These findings provide new insights into the mechanism underlying the regulation of the self-antigen repertoire in eliciting anti-tumor immune reactions in patients with polycythemia vera, and suggest their potential as the targets of novel immunotherapy.

Antibodies, Neoplasm↗
PubMed2006

An unconventional antigen translated by a novel internal ribosome entry site elicits antitumor humoral immune reactions.

Self-tumor Ags that elicit antitumor immune responses in responses to IFN-alpha stimulation remain poorly defined. We screened a human testis cDNA library with sera from three polycythemia vera patients who responded to IFN-alpha and identified a novel Ag, MPD6. MPD6 belongs to the group of cryptic Ags without conventional genomic structure and is encoded by a cryptic open reading frame located in the 3'-untranslated region of myotrophin mRNA. MPD6 elicits IgG Ab responses in a subset of polycythemia vera patients, as well as patients with chronic myelogenous leukemia and prostate cancer, suggesting that it is broadly immunogenic. The expression of myotrophin-MPD6 transcripts was up-regulated in some tumor cells, but only slightly increased in K562 cells in response to IFN-alpha treatment. By using bicistronic reporter constructs, we showed that the translation of MPD6 was mediated by a novel internal ribosome entry site (IRES) upstream of the MPD6 reading frame. Furthermore, the MPD6-IRES-mediated translation, but not myotrophin-MPD6 transcription, was significantly up-regulated in response to IFN-alpha stimulation. These findings demonstrate that a novel IRES-mediated mechanism may be responsible for the translation of unconventional self-Ag MPD6 in responsive to IFN-alpha stimulation. The eliciting antitumor immune response against unconventional Ag MPD6 in patients with myeloproliferative diseases suggests MPD6 as a potential target of novel immunotherapy.

Amino Acid Sequence↗
PubMed2006

Model of stimulation-responsive splicing and strategies in identification of immunogenic isoforms of tumor antigens and autoantigens.

We recently proposed a novel model of stimulation-responsive splicing for the selection of autoantigens and self-tumor antigens. Our model theorizes that the significantly higher rates of alternative splicing of autoantigen and self-tumor antigen transcripts that occur in response to stimuli could induce extra-thymic expression of untolerized antigen epitopes for elicitation of autoimmune and anti-tumor responses. To facilitate the identification of immunogenic isoforms of antigens, we have developed strategies using improved SEREX in conjunction with database-mining and immunogenic isoform mapping. Identification of immunogenic isoforms of autoantigens and self-tumor antigens is very important for the development of novel therapeutics and diagnostic tools for autoimmune diseases and tumors, such as: (1) autoantigen isoform microarrays for disease diagnosis and prognosis; (2) autoantigen isoform-specific tolerizing vaccines and splicing-redirection therapies, as well as (3) immunogenic antigen isoform-specific immunotherapy for tumors.

Alternative Splicing↗
PubMed2006

Novel fluorogenic probe for fluoride ion based on the fluoride-induced cleavage of tert-butyldimethylsilyl ether.

A highly sensitive and selective fluorogenic probe for fluoride ion, 4-methylumbelliferyl tert-butyldimethylsilyl ether (4-MUTBS), was designed and synthesized. 4-MUTBS was a weakly fluorescent compound and was synthesized via the one-step reaction of 4-MU with tert-butyldimethylsilyl chloride. Upon incubation with fluoride ion in acetone-water solution (7:3, v/v), the Si-O bond of 4-MUTBS was cleaved and highly fluorescent 4-methylumbelliferone (4-MU) was released, hence leading to the fluorescence increase of the reaction solution. The fluorescence increase is linearly with fluoride concentration in the range 50-8000 nmol l(-1) with a detection limit of 19 nmol l(-1) (3sigma). Because of the high affinity of silicon toward fluoride ion, the proposed probe shows excellent selectivity toward fluoride ion over other anions. The method has been successfully applied to the fluoride determination in toothpaste and tap water samples.

Fluorescent Dyes↗
PubMed2006

Cooling produces minimal neuropathology in neocortex and hippocampus.

Cooling is a potential treatment for several neurological diseases. We have examined rodent and cat neocortex, cooled to 5 and 3 degrees C, respectively, to identify a lower limit for safely cooling brain. Rat neocortex, intermittently cooled with a thermoelectric device for 2 h, showed no signs of neuronal injury after cresyl violet or TUNEL staining. Neurons were also preserved in cat cortex cooled for up to 2 h daily for 10 months. Cooled rat and cat cortex showed glial proliferation, but this was also observed in sham-operated rat cortex. When hippocampal slices from mice expressing the Green Fluorescent Protein (GFP) in neurons were cooled to 5 degrees C, but not higher temperatures, we saw reversible dendritic beading and spine loss after 15-30 min. While there may be biochemical and functional alterations in brain cooled as low as 5 degrees C, the neuropathological consequences of brain cooling appear to be insignificant.

Animals↗
PubMed2006

Selective thiourea optical probe based on thiourea-induced removal of chloroacetyl group from chloroacetylamine.

A novel chromogenic probe for thiourea, N-chloroacetyl parafuchsin (CAP), was designed and synthesized. The method was based on the reaction of CAP with thiourea, resulting in the initial formation of the S-substituted thioformamidine hydrochloride, which would then undergo the intramolecular amidinolysis to liberate the corresponding amine, and thus leading to an absorbance increase at visible spectral range. Based on this mechanism, a highly selective optical probe for thiourea was developed. Under optimal conditions, absorbance increase (DeltaA) at 562 nm is proportional to thiourea concentration up to 0.2 mmolL(-1) with a detection limit of 2.1 micromolL(-1) (3sigma). Because of the selective removal of chloroacetyl group from CAP by thiourea, there is little interference by other molecules.

Acetamides↗
PubMed2006

[New principles in tumor antigens and their significance in future immunotherapies for lymphomas and other malignancies--editorial].

The molecular characterization of self-antigens expressed by human malignancies that are capable of elicitation of anti-tumor immune responses in patients has been an active field in hematology, oncology, and tumor immunology. More than 2000 tumor antigens have been identified. These significant progresses have led to the renaissance of tumor immunology and studies on novel anti-tumor immunotherapies in lymphomas, other hematologic malignancies and tumors. However, despite of the progress in the identification of these self-tumor antigens, current antigen-specific immunotherapies for tumors are far less satisfactory than that expected, which reflects the urgent need to improve our understanding on the basic principles underlying the selection of these self-tumor antigens. In order to develop more effective antigen-specific anti-tumor immunotherapies and to monitor the responses to these immunotherapies in patients with lymphomas and other malignancies, many additional questions need to be addressed. In this brief review, the progress in the identification of tumor antigens in lymphomas and other malignancies was outlined and the new principles of self-tumor antigens and their significance for future immunotherapies to these malignancies were summarized.

Antigens, Neoplasm↗
PubMed2006

[Optimization of SRAP & ISSR technology and its application in the identification of seeds of Brassica oleracea L].

In this study, the molecular marker technology of SRAP and ISSR were applied in rapid identification of seeds from eight species of Brassica oleracea L. Firstly, using the genomic DNA of cabbage as template, SRAP and ISSR reaction systems were optimized through testing every factor, respectively, that affects PCR amplification. Then, using the optimized reaction systems, 30 SRAP primer pairs and 15 ISSR primers were applied to amplify genomic DNA of cabbage, savoy, purple cabbage, borecole, cauliflower, broccoli, Brussels sprouts, and kohlrabi The results showed that high polymorphisms were exhibited among the eight species of Brassica oleracea L. by SRAP primer pairs of M3-E5 and M4-E5, as well as ISSR primers of 844 and 888, especially primer 844 which can identify all eight materials efficiently.

Brassica↗
PubMed2005

Bcl-xL inhibits T-cell apoptosis induced by expression of SARS coronavirus E protein in the absence of growth factors.

One of the hallmark findings in patients suffering from SARS (severe acute respiratory syndrome) is lymphopenia, which is the result of massive lymphocyte death. SARS-CoV (SARS coronavirus), a novel coronavirus that has been etiologically associated with SARS cases, is homologous with MHV (murine hepatitis coronavirus), and MHV small envelope E protein is capable of inducing apoptosis. We hypothesized that SARS-CoV encodes a small envelope E protein that is homologous with MHV E protein, thus inducing T-cell apoptosis. To test this hypothesis, a cDNA encoding SARS-CoV E protein was created using whole gene synthesis. Our results showed that SARS-CoV E protein induced apoptosis in the transfected Jurkat T-cells, which was amplified to higher apoptosis rates in the absence of growth factors. However, apoptosis was inhibited by overexpressed antiapoptotic protein Bcl-xL. Moreover, we found that SARS-CoV E protein interacted with Bcl-xL in vitro and endogenous Bcl-xL in vivo and that Bcl-xL interaction with SARS-CoV E protein was mediated by BH3 (Bcl-2 homology domain 3) of Bcl-xL. Finally, we identified a novel BH3-like region located in the C-terminal cytosolic domain of SARS-CoV E protein, which mediates its binding to Bcl-xL. These results demonstrate, for the first time, a novel molecular mechanism of T-cell apoptosis that contributes to the SARS-CoV-induced lymphopenia observed in most SARS patients.

Amino Acid Sequence↗
PubMed2005

An N-terminal region of translationally controlled tumor protein is required for its antiapoptotic activity.

Bcl-xL plays a critical role in maintaining cell survival. However, the relationship between the potential interaction of Bcl-xL with other cytosolic proteins and the regulation of cell survival remains incompletely defined. We have identified translationally controlled tumor protein (TCTP), a multifunctional protein, as a novel antiapoptotic Bcl-xL-interacting protein. TCTP interacted in vivo and in vitro with Bcl-xL, and their sites have been mapped to an N-terminal region of TCTP and the Bcl-2 homology domain 3 of Bcl-xL. Consistent with a role in maintaining T-cell survival during activation, TCTP was significantly upregulated in murine T cells activated by T-cell antigen receptor (TCR) ligation and CD28 costimulation, which was correlated with the upregulation of Bcl-xL in activated T cells. Moreover, downregulation of TCTP expression by antisense technology in T cells results in the increase of T-cell apoptosis. Furthermore, the N-terminal region of TCTP was required for its ability to inhibit apoptosis. In conclusion, this study has demonstrated that an N-terminal region of a cytosolic protein, TCTP, is required for its binding to Bcl-xL and for its antiapoptotic activity.

Amino Acid Sequence↗
PubMed2005

Cooling blocks rat hippocampal neurotransmission by a presynaptic mechanism: observations using 2-photon microscopy.

Over the past decade there has been great interest in the therapeutic potential of brain cooling for epilepsy, stroke, asphyxia and other neurological diseases. However, there is still no consensus regarding the neurophysiological effect(s) of brain cooling. We employed standard physiological techniques and 2-photon microscopy to directly examine the effect of temperature on evoked neurotransmitter release in rat hippocampal slices. We observed a monotonic decline in extracellular synaptic potentials and their initial slope over the temperature range 33-20 degrees C, when the slices were cooled to a new set point in less than 5 s. Imaging the fluorescent synaptic marker FM1-43 with 2-photon microscopy showed that the same cooling protocol dramatically reduced transmitter release between 33 and 20 degrees C. Cooling also reduced the terminal FM1-43 destaining that was induced by direct depolarization with elevated K+, indicating that axonal conduction block cannot account for our observations. The temperature dependence of FM1-43 destaining correlated well with the effect of temperature on field potential slope, compatible with a presynaptic explanation for our electrophysiological observations. Optical measurement of FM1-43 dissociation from cell membranes was not affected by temperature, and rapid cooling of slices loaded with FM1-43 did not increase their fluorescence. Our experiments provide visible evidence that a major neurophysiological effect of cooling in the mammalian brain is a reduction in the efficacy of neurotransmitter release. This presynaptic effect may account for some of the therapeutic benefits of cooling in epilepsy and possibly stroke.

Animals↗
PubMed2005

Graft-versus-leukemia target antigens in chronic myelogenous leukemia are expressed on myeloid progenitor cells.

PURPOSE: Donor lymphocyte infusion (DLI) reliably induces durable remission in 75% to 80% of patients with relapsed chronic myelogenous leukemia (CML) following allogeneic bone marrow transplantation. We previously reported the identification of a high titer-specific immunoglobulin G response against two novel leukemia-associated antigens, CML28 and CML66, which correlated with immune-induced remission. The present studies characterize expression of CML28 and CML66 in primary hematopoietic tissues. EXPERIMENTAL DESIGN: Specific monoclonal antibodies to CML28 and CML66 were developed and used to detect antigen expression in leukemia cell lines and primary leukemia tissue on Western blot and immunohistochemistry. Expression patterns were confirmed by antigen-specific real-time PCR. RESULTS: Both CML28 and CML66 were highly expressed in leukemic blasts from patients with acute myelogenous leukemia and CML blast crisis but barely detectable in normal bone marrow, normal peripheral blood, or leukemic cells from patients with stable-phase CML. In contrast, purified CD34+ progenitors from normal individuals and patients with stable-phase CML expressed high levels of CML28 and CML66 transcript and protein. Immunohistochemical staining for CML66 confirmed rare staining of myeloid precursors in normal marrow and diffuse staining of myeloblastic cells in acute myelogenous leukemia and blast crisis CML marrows. CONCLUSIONS: The expression patterns of CML28 and CML66 are strikingly similar and suggest that antigen expression may play a role in shaping the post-DLI antibody repertoire. The CD34+ restricted pattern of expression of CML28 and CML66 is particularly relevant in light of the notion that DLI likely exerts its curative effect by targeting antigens present in self-renewing malignant progenitor populations in CML.

Antibody Specificity↗
PubMed2005

In vivo imaging of dendritic spines during electrographic seizures.

Epilepsy is associated with significant neurological morbidity, including learning disabilities, motor deficits, and behavioral problems. Although the causes of neurological dysfunction in epilepsy are multifactorial, accumulating evidence indicates that seizures in themselves may directly cause brain injury. Although it is clear that seizures can result in neuronal death, it is likely that under some circumstances seizures can induce more subtle functional or structural alterations in neurons. We induced focal neocortical seizures with 4-aminopyridine in transgenic mice expressing green fluorescent protein in cortical neurons and sequentially imaged individual dendrites in living animals with two-photon laser-scanning microscopy to determine whether these seizures caused acute alterations in dendritic spine morphology. No dendritic alterations were observed in anesthetized animals during electrographic seizures over a 3-hour period. Similarly, in unanesthetized mice, low-stage, clinical electrographic seizures had minimal effect on dendritic spines. More severe, high-stage seizures in unanesthetized mice were associated with a moderate loss of spines and dendritic swelling, but this effect may have been contingent on a synergistic action of phototoxicity from the imaging method itself. Overall, our results suggest that most neocortical seizures have minimal acute effects on dendrites over several hours, but may predispose to dendritic injury under extreme conditions.

4-Aminopyridine↗
PubMed2005

Focal cooling for epilepsy: an alternative therapy that might actually work.

The therapy of focal epilepsy remains inadequate. Many patients who have localization-related seizures find themselves either overmedicated with anticonvulsants or suffering from frequent seizures. While surgical resection can lead to excellent outcomes in up to 60% of patients with neocortical epilepsy, there are obviously many who either fail surgery or are deemed inappropriate surgical candidates. We are currently determining the efficacy of local cooling for the therapy of certain focal epilepsies. We have attempted to adapt new technologies borrowed from electrical and mechanical engineering to develop cooling devices that will ultimately improve the diagnosis and therapy of these focal epilepsies. The present review describes the rationale for this research and our progress to date.

Animals↗