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Biomedical subjects

Bo Huang

Publications and source records attributed to Bo Huang.

At least 37 records · Page 2Linked to original sources
PubMed2006

Gr-1+CD115+ immature myeloid suppressor cells mediate the development of tumor-induced T regulatory cells and T-cell anergy in tumor-bearing host.

The accumulation of myeloid suppressor cells (MSCs) is associated with immune suppression in tumor-bearing mice and in cancer patients. The suppressive activity of MSC correlates with the expression of the myeloid markers Gr-1, CD115 (macrophage colony-stimulating factor receptor), and F4/80. Gr-1(+)CD115(+) MSCs, in addition to being able to suppress T-cell proliferation in vitro, can induce the development of Foxp3(+) T regulatory cells (Treg) in vivo, which are anergic and suppressive. Furthermore, the secretion of interleukin (IL)-10 and transforming growth factor-beta by Gr-1(+)CD115(+) MSCs was induced and enhanced, respectively, on IFN-gamma stimulation. The development of Treg requires antigen-associated activation of tumor-specific T cells, depends on the presence of IFN-gamma and IL-10, and is independent of the nitric oxide-mediated suppressive mechanism by MSC. Our data provide evidence that Gr-1(+)CD115(+) MSC can mediate the development of Treg in tumor-bearing mice and show a novel immune suppressive mechanism by which MSCs can suppress antitumor responses.

Animals↗
PubMed2006

Bioactive oligostilbenoids from the stem bark of Hopea exalata.

Hopeanolin (1), an unusual resveratral trimer with an ortho-quinone nucleus, was isolated and characterized from the stem bark of Hopea exalata. Also obtained were six known stibenoids, shoreaphenol (2), vaticanol G (3), alpha-viniferin (4), pauciflorol A (5), vaticanol A (6), and trans-3,5,4'-trihydroxystilbene 2-C-glucoside (7). The structure of 1 was determined by spectroscopic data interpretation. Compounds 1-7 were tested for antifungal activity and inhibitory effects against jack bean urease. Hopeanolin (1) demonstrated antifungal activity in the MIC value range 0.1-22.5 microg/mL.

Antifungal Agents↗
PubMed2005

Plasma metallothionein antibody and cadmium-induced renal dysfunction in an occupational population in China.

It has been reported that anti-metallothionein (a metallothionein antibody) is present in the circulation of healthy subjects and in patients suffering from atopic dermatitis. The aim of this study was to investigate whether cadmium-induced renal dysfunction is related to the presence of the plasma metallothionein antibody (MT-Ab) in workers exposed to cadmium (Cd) occupationally. Plasma metallothionein antibody was determined by enzyme linked immunosorbent assay (ELISA) techniques, and both exposure assessment and risk assessment were conducted in cadmium-exposed workers in China. We demonstrate that there is a significantly increased prevalence of renal dysfunction with respect to the level of urinary cadmium in a dose-dependent manner. We found no significant correlations between the levels of MT-Ab and the external or internal exposure doses of cadmium (p > 0.05), but the levels of MT-Ab did correlate positively with two biomarkers of renal dysfunction-urinary beta2-microglobulin (UB2M; r = 0.218, p < 0.05) and N-acetyl-beta-D-glucosaminidase (UNAG; r = 0.302, p < 0.001)-in the cadmium-exposed workers. Workers who have high levels of MT-Ab display cadmium-induced tubular nephrotoxicity more frequently than those possessing low levels of MT-Ab; odds ratio (OR) 4.2; 95% confidence intervals 1.2-14.5 (p < 0.05). This study suggests that subjects that have higher MT-Ab levels more readily develop cadmium-induced renal dysfunction. Thus, the levels of plasma MT-Ab can be used as a biomarker of susceptibility to renal dysfunction in occupational cadmium exposure.

Adult↗
PubMed2005

Construction of microfluidic chips using polydimethylsiloxane for adhesive bonding.

A thin layer of polydimethylsiloxane (PDMS) prepolymer, which is coated on a glass slide, is transferred onto the embossed area surfaces of a patterned substrate. This coated substrate is brought into contact with a flat plate, and the two structures are permanently bonded to form a sealed fluidic system by thermocuring (60 degrees C for 30 min) the prepolymer. The PDMS exists only at the contact area of the two surfaces with a negligible portion exposed to the microfluidic channel. This method is demonstrated by bonding microfluidic channels of two representative soft materials (PDMS substrate on a PDMS plate), and two representative hard materials (glass substrate on a glass plate). The effects of the adhesive layer on the electroosmotic flow (EOF) in glass channels are calculated and compared with the experimental results of a CE separation. For a channel with a size of approximately 10 to 500 microm, a approximately 200-500 nm thick adhesive layer creates a bond without voids or excess material and has little effect on the EOF rate. The major advantages of this bonding method are its generality and its ease of use.

Adhesiveness↗
PubMed2005

Toll-like receptors on tumor cells facilitate evasion of immune surveillance.

The signal pathways that trigger tumor cell escape from immune surveillance are incompletely understood. Toll-like receptors (TLRs), which activate innate and adaptive immune responses, are thought to be restricted to immune cells. We show here that TLRs, including TLR4, are expressed on tumor cells from a wide variety of tissues, suggesting that TLR activation may be an important event in tumor cell immune evasion. Activation of TLR4 signaling in tumor cells by lipopolysaccharide induces the synthesis of various soluble factors and proteins including interleukin-6, inducible nitric oxide synthase, interleukin-12, B7-H1, and B7-H2, and results in resistance of tumor cells to CTL attack. In addition, lipopolysaccharide-stimulated tumor cell supernatants inhibit both T cell proliferation and natural killer cell activity. Blockade of the TLR4 pathway by either TLR4 short interfering RNA or a cell-permeable TLR4 inhibitory peptide reverses tumor-mediated suppression of T cell proliferation and natural killer cell activity in vitro, and in vivo, delays tumor growth and thus prolongs the survival of tumor-bearing mice. These findings indicate that TLR signaling results in a cascade leading to tumor evasion from immune surveillance. These novel functions of TLRs in tumor biology suggest a new class of therapeutic targets for cancer therapy.

Amino Acid Sequence↗
PubMed2005

Ubiquitin-dependent degradation of interferon regulatory factor-8 mediated by Cbl down-regulates interleukin-12 expression.

Interferon regulatory factor (IRF)-8/interferon consensus sequence-binding protein is regulated by both transcription and degradation. IRF-8 induced in peritoneal macrophages by interferon-gamma and lipopolysaccharide was degraded rapidly, and degradation of IRF-8 was blocked by MG132, the proteasome inhibitor, but inhibitors of calpain and lysosomal enzymes had no effect. The ubiquitination of IRF-8 was shown by co-immunoprecipitation from RAW264.7 macrophages retrovirally transduced with IRF-8 and hemagglutinin-ubiquitin. The dominant negative ubiquitin mutants K48R and K29R inhibited IRF-8 degradation in 293T cells, confirming the relationship between ubiquitination of IRF-8 and its degradation. IRF-8 carboxyl-terminal truncation mutants were not ubiquitinated and were consequently stable, indicating that the carboxyl-terminal domain of IRF-8 controls ubiquitination. The ubiquitin-protein isopeptide ligase (E3) that ubiquitinated IRF-8 was likely to be Cbl, which formed a complex with IRF-8, demonstrable by both immunoprecipitation and gel filtration. Furthermore, IRF-8 stability was increased by dominant negative Cbl, and IRF-8 ubiquitination was significantly attenuated in Cbl-/- cells. Reflecting increased stability and expression, the IRF-8 carboxyl-terminal deletion mutant induced interleukin (IL)-12 p40 promoter activity much more strongly than IRF-8 did. Furthermore, IRF-8-induced IL-12 p40 synthesis in RAW264.7 cells was enhanced by dominant negative Cbl, and peritoneal macrophages from Cbl-/- mice showed increased IL-12 p40 protein production. Taken together, these results suggest that the proteasomal degradation of IRF-8 mediated by the ubiquitin E3 ligase Cbl down-regulates IL-12 expression.

Animals↗
PubMed2005

Effect of bin time on the photon counting histogram for one-photon excitation.

We have demonstrated that our photon counting histogram (PCH) model with the correction for one-photon excitation is valid at multiple bin times. The fitted apparent brightness and concentration follow the three-dimensional diffusion model. More importantly, the semi-empirical parameter, F, introduced in the PCH model for one-photon excitation to correct for the non-Gaussian shape of the observation volume, shows small variations with different bin times. These variations are consistent with the physical interpretation of F, and they do not affect the resolving power of the PCH model for one-photon excitation. Based on these findings, we extend the time-independent PCH analysis to time-dependent photon counting multiple histograms (PCMH). This model considers the effect of bin time on the PCH parameters in a way that is similar to fluorescence intensity multiple distribution analysis (FIMDA). From the same set of data, PCMH extracts time-dependent parameters (diffusion time and triplet-state relaxation time) as well as time-independent parameters (true specific brightness and true average number of molecules). Given a three- to fourfold experimental difference in molecular brightness, we find that PCMH can resolve each species in a two-species sample and extract their respective diffusion times even when fluorescence correlation spectroscopy cannot.

Algorithms↗
PubMed2005

Effects of total flavonoids of Hippophae rhamnoides L. on intracellular free calcium in cultured vascular smooth muscle cells of spontaneously hypertensive rats and Wistar-Kyoto rats.

OBJECTIVE: To explore the effects of total flavonoids of Hippophae rhamnoides L. (TFH), quercetin (Que) and isorhamnetin (Isor) on the intracellular free calcium ([Ca(2+)](i)) in vascular smooth muscle cells (VSMC) of spontaneously hypertensive rats (SHR) and Wistar-Kyoto rats (WKY). METHODS: Fluo 3-acetoxymethylester (Fluo-3/AM) was used to observe the effects of TFH (100 mg/L) and its essential monomers, namely Que (10(-4) mol/L) and Isor (10(-4) mol/L) on changes of [Ca(2+)](i) in cultured SHR and WKY VSMC (abbr. to Ca-SHR & Ca-WKY) following exposure to high K(+), norepinephrine (NE) and angiotensin II (Ang II), and to compare with the effects of verapamil (Ver). RESULTS: (1) TFH, Que and Isor had inhibitory effects on resting Ca-SHR (P < 0.05), but had no significant effects on Ca-WKY (P > 0.05). (2) High K(+) could increase Ca-SHR more significantly than Ca-WKY (P < 0.05); TFH, Que and Isor could inhibit the elevation of [Ca(2+)](i) induced by high K(+)-depolarization, with the effects similar to that of Ver, and the effect on Ca-SHR was more significant than that on Ca-WKY (P < 0.05). (3) NE and Ang II could increase Ca-SHR more significantly than Ca-WKY (P < 0.05), TFH, Que and Isor had remarkably inhibitory effect on the elevation of Ca-SHR and Ca-WKY induced by NE or Ang II. (4) In the absence of extracellular Ca(2+), TFH, Que and Isor also had certain inhibitory effect on Ca-SHR and Ca-WKY induced by NE, and the effect on the former was more significant than that on the latter (P < 0.05). CONCLUSION: TFH, Que and Isor might decrease the levels of [Ca(2+)](i) in VSMCs by blocking both voltage-dependent calcium channels (VDC) and receptor-operated calcium channels (ROC) in physiological or pathological state, which may be one of the important mechanisms of their hypotensive and protective effects on target organs in patients with hypertension.

Angiotensin II↗
PubMed2005

Genetic diversity and population structure among strains of the entomopathogenic fungus, Beauveria bassiana, as revealed by inter-simple sequence repeats (ISSR).

Inter-simple sequence repeat (ISSR) markers were used to investigate genetic diversity among 39 isolates of Beauveria spp. (36 B. bassiana, one B. brongniartii, one B. amorpha, and one B. velata) isolated from different insect hosts and geographical origins. Eighteen among 33 primers that contained different simple sequence repeats (SSR) were chosen for their reproducibility and high polymorphism. Considerable intraspecific and interspecific variability among the isolates of Beauveria spp. was revealed. One hundred sixty-eight highly reproducible fragments were amplified in all 39 isolates with an average of 9.3 markers per primer; among these, 161 (95.8%) were polymorphic. For 36 B. bassiana isolates, 8.9 (1-13) markers per primer were scored, and a total of 123 fragments were amplified, in which 102 (82.9%) were polymorphic. Among the 168 polymorphic bands, 7 bands were considered to be specific for B. brongniartii isolate Bbr06, 14 bands for B. amorpha isolate Ba08, and 18 bands for B. velata isolate Bv0. Within 36 B. bassiana isolates, genetic similarity ranged from 0.651 to 0.972. However, the genetic similarity values among different Beauveria species ranged from 0.411 to 0.720, suggesting that ISSR technique was successful in differentiating the three closely related species from B. bassiana. The results also indicated that there was a certain association between B. bassiana isolates and their geographical origins, but no clear correlation between those isolates and their insect hosts. The present study suggested that ISSR markers can be used as robust molecular markers for the population genetics, epidemiological and ecological studies of entomopathogenic fungi.

Animals↗
PubMed2005

The Kluyveromyces lactis gamma-toxin targets tRNA anticodons.

Kluyveromyces lactis killer strains secrete a heterotrimeric toxin (zymocin), which causes an irreversible growth arrest of sensitive yeast cells. Despite many efforts, the target(s) of the cytotoxic gamma-subunit of zymocin has remained elusive. Here we show that three tRNA species tRNA(Glu)(mcm(5)s(2)UUC), tRNA(Lys)(mcm(5)s(2)UUU), and tRNA(Gln)(mcm(5)s(2)UUG) are the targets of gamma-toxin. The toxin inhibits growth by cleaving these tRNAs at the 3' side of the modified wobble nucleoside 5-methoxycarbonylmethyl-2-thiouridine (mcm(5)s(2)U). Transfer RNA lacking a part of or the entire mcm(5) group is inefficiently cleaved by gamma-toxin, explaining the gamma-toxin resistance of the modification-deficient trm9, elp1-elp6, and kti11-kti13 mutants. The K. lactis gamma-toxin is the first eukaryotic toxin shown to target tRNA.

Anticodon↗
PubMed2005

An early step in wobble uridine tRNA modification requires the Elongator complex.

Elongator has been reported to be a histone acetyltransferase complex involved in elongation of RNA polymerase II transcription. In Saccharomyces cerevisiae, mutations in any of the six Elongator protein subunit (ELP1-ELP6) genes or the three killer toxin insensitivity (KTI11-KTI13) genes cause similar pleiotropic phenotypes. By analyzing modified nucleosides in individual tRNA species, we show that the ELP1-ELP6 and KTI11-KTI13 genes are all required for an early step in synthesis of 5-methoxycarbonylmethyl (mcm5) and 5-carbamoylmethyl (ncm5) groups present on uridines at the wobble position in tRNA. Transfer RNA immunoprecipitation experiments showed that the Elp1 and Elp3 proteins specifically coprecipitate a tRNA susceptible to formation of an mcm5 side chain, indicating a direct role of Elongator in tRNA modification. The presence of mcm5U, ncm5U, or derivatives thereof at the wobble position is required for accurate and efficient translation, suggesting that the phenotypes of elp1-elp6 and kti11-kti13 mutants could be caused by a translational defect. Accordingly, a deletion of any ELP1-ELP6 or KTI11-KTI13 gene prevents an ochre suppressor tRNA that normally contains mcm5U from reading ochre stop codons.

Acetyltransferases↗
PubMed2005

[Relationship between expression of multidrug-resistant genes in nasopharyngeal carcinoma tissue and sensitivity to chemotherapy].

OBJECTIVE: To study the relationship between multidrug-resistant (MDR) expression in nasopharyngeal carcinoma (NPC) and its sensitivity to chemotherapy. METHODS: The specimens of 23 NPC cases were studied by immunohistochemistry with monoclonal antibody of P-glycoprotein (P-gp), multidrug resistance relation protein (MRP), lung-resistance related protein (LRP), topoisomerase II (Topo II), thymidylate synthase (TS), glutathione-S-transferase (GST-pi). Among them, 20 specimens were taken from primary NPC lesion which were treated with two course of cisplatin (DDP) and 5-fluorouracil (5-FU), 3 specimens were taken from cervical lymph-node of recurrent NPC patients who were treated by radical dissection. RESULTS: Various MDR parameters were expressed differently in 22 cases except for 1 clear cell carcinoma case. The difference was statistically significant (P < 0.05). However, there were no significant difference of MDR expression either among various carcinoma pathomorphology cell groups or among different clinical stage groups. Expression of LRP and TS were found in 10 and 14 cases respectively and the chemotherapy responders rates were 20% (2/10) and 28.5% (4/14) respectively. While the chemotherapy responders rates were 70% (7/10) and 5/6 in cases without expression. There was significant difference (P < 0.001, and P < 0.05). CONCLUSION: The NPC patients with LRP and TS expression may be less sensitive to chemotherapy with DDP + 5-FU.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed2004

Photon counting histogram: one-photon excitation.

The photon counting histogram (PCH) analysis is a fluorescence fluctuation method that is able to characterize the brightness and concentration of different fluorescent species present in a liquid sample. We find that the PCH model using a three-dimensional Gaussian observation volume profile is inadequate for fitting experimental data obtained from a confocal setup with one-photon excitation. We propose an imoroved model, which is based on the correction to the observation volume profile for the out-of-focus emission. We demonstrate that this model is able to resolve different species present under a wide range of conditions. Attention is given to how this model allows the examination of the effects of different instrumental setups on the resolvability.

Journal Article↗
PubMed2004

The effect of punctal occlusion on wavefront aberrations in dry eye patients after laser in situ keratomileusis.

PURPOSE: To compare the wavefront aberrations in post-laser in situ keratomileusis (LASIK) dry eye patients before and after punctal occlusion. DESIGN: Prospective, comparative, nonrandomized study. METHODS: Wavefront aberrometry was performed on 16 eyes of eight patients with dry eyes after LASIK surgery. Wavefront measurements were taken before and 1 month after punctal plug placement and compared with 10 eyes of post-LASIK patients without clinically dry eyes measured twice 1 month apart. Student t tests were used to assess the statistical significance of differences between pre- and post-punctal plug measurements. RESULTS: Punctal occlusion in the post-LASIK dry eye patients significantly reduced total, lower, and higher order wavefront aberrations by 47% to 63% (P <.01). Among higher-order aberrations, there were significant reductions in coma and spherical aberration but not in trefoil, after punctal occlusion. The reduction of wavefront aberrations by punctal occlusion in post-LASIK dry eye patients resulted in a significant improvement in quantitative visual acuity assessed using an Early Treatment of Diabetic Retinopathy Study chart and in subjective qualitative vision, confirmed by convolutional analysis using image simulation. No statistically significant differences in any of these metrics were found in the post-LASIK control group without clinically dry eyes measured twice at a similar time interval. CONCLUSIONS: Wavefront aberrometry provides a useful, objective assessment of post-LASIK dry eye patients before and after punctal plug placement. Aggressive treatment of dry eyes may be important before obtaining wavefront measurements that serve as the basis for planning refractive corneal laser treatments and retreatments.

Adult↗
PubMed2004

Lack of reversal effect of EDTA treatment on cadmium induced renal dysfunction: a fourteen-year follow-up.

The aim of this study was to evaluate the effect of ethylenediaminetetraacetic acid (EDTA) on cadmium (Cd) induced renal dysfunction. Seventeen workers (14 males, 3 females) were diagnosed with occupational Cd poisoning in 1986. These individuals had between 7 to 39 years of Cd exposure. From 1986 to 1999, patients received periodic EDTA therapy as part of their follow-up, all at the same hospital. Levels of urinary cadmium (UCd) and urinary beta2-microglobulin (B2M) were measured before and after each annual EDTA treatment period. Renal dysfunction was defined as urinary B2M > 0.8 mg/g Cr (creatinine). In these workers, patients with UCd level higher than 10 microg/g Cr in 1986 had abnormal B2M excretions (> or = 0.8 mg/g Cr) or trended to have abnormal B2M levels during the treatment period. However, in subjects with UCd concentration lower than 10 microg/g Cr in 1986, their urinary B2M excretions either remained normal (< 0.8 mg/g Cr) or returned to normal during the treatment period. The prevalence of renal dysfunction increased during the follow up period regardless of whether UCd levels increased or not, indicating a progressive renal dysfunction despite removal from Cd exposure. Our results suggest that reversibility of renal dysfunction caused by Cd related to the level of Cd exposure at the time of removal from exposure: renal dysfunction could be reversed if initial UCd < 10 microg/g Cr, but was irreversible when UCd > 10 microg/g Cr. Repeated examinations on these 17 Cd exposed workers from 1986 to 1999 also revealed that periodic administration of EDTA had no beneficial effects on chronic Cd-induced renal dysfunction.

Adult↗