Biomedical subjects

Lei Zhang

Publications and source records attributed to Lei Zhang.

At least 271 records · Page 15Linked to original sources

PubMed2005

Influenza vaccination in Mississippi, 1992-2003: trends, subgroup comparisons, and forecast.

OBJECTIVES: We examined longitudinal trends in relative frequency of influenza vaccination in the state of Mississippi. METHODS: An influenza vaccination questionnaire was used to assess status among 20,078 adults who were sampled in random-digit-dialed telephone surveys administered in 1992, 1993, 1995, 1997, 1999, 2001, 2002, and 2003. Time trends were evaluated using logistic regression models in which the status of influenza vaccination was regressed on the respondents' gender, race, education, and household income. RESULTS: In Mississippi, influenza vaccination rates increased substantially during 1992-2003 irrespective of gender, race/ethnicity, age, education, and household income. The increases showed a significant linear trend. Non-Hispanic blacks were significantly less likely to have been vaccinated for influenza compared to non-Hispanic whites without accounting for gender, age, education, and household income. Having a college degree was associated with higher vaccination rates among older Mississippians after adjusting for other factors. CONCLUSIONS: Although vaccination coverage is increasing, the national goal for 2010 does not appear achievable without new initiatives. Meanwhile, we should continue to provide funding for the immunization program and to educate the population regarding their compliance.

Adolescent↗

PubMed2005

[The expression of Maspin and VEGF gene in oral squamous cell carcinoma and its significance].

PURPOSE: To study the expression of Maspin(marray serine proteinase inhibitor) and VEGF(vascular endothelial growth factor) gene in oral squamous cell cancers(OSCC) and the relationship between Maspin and VEGF. METHODS: mRNA expression of Maspin and VEGF gene was investigated by RT-PCR in every samples of 18 OSCC cases. F test and Person test were used for data analysis. RESULTS: mRNA expression of Maspin gene increased gradually in OSCC, paratumor and normal epithelium(P<0.01); mRNA expression of VEGF gene decreased gradually in OSCC,paratumor and normal epithelium(P<0.01); The expression of Maspin and VEGF gene was negatively correlated in OSCC(P<0.01) ; The expression of Maspin gene was negatively associated but VEGF gene was positively associated with lymph node metastasis in OSCC(P<0.05); The expression of Maspin and VEGF gene had no relation with the histological grade or tumor size in OSCC. CONCLUSION: Maspin and VEGF gene may play an important role in the development of OSCC and Maspin gene may down-regulate the expression of VEGF gene.

Carcinoma, Squamous Cell↗

PubMed2005

[Study on the metabolism of the precipitation of Xiexin decoction in rats I].

OBJECTIVE: To study the process in vivo of the components in the precipitation of Xiexin decoction. METHOD: The components in the rats' urine samples after oral administration of baicalin, single herb decoction of Radix Scutellariae or the precipitation of Xiexin decoction were analyzed by LC-MS-MS method; and the absorption of baicalin in different samples were calculated by intestinal in situ loop method. RESULT: The urinary excretion amounts of baicalin in three samples were not obviously different, whereas the time reach elimination-peak of baicalin in them had significant difference. The absorption of baicalin in the precipitation was obviously greater than that in the single herb decoction and single baicalin. We found that wogonoside and 7-O-glucuronide chrysin were the metabolites presenting in the rat urine samples after oral administration of baicalin by LC-MS-MS, which had never been reported. CONCLUSION: The resident time in the body of baicalin in the precipitation is prolonged, compared with that in the single herb decoction and single baicalin. The metabolites may be the potential biological components in vivo of baicalin in the precipitation.

Administration, Oral↗

PubMed2005

[Application of supraomohyoid neck dissection in oral squamous cell carcinoma with clinically N0 neck].

OBJECTIVES: The value of supraomohyoid neck dissection used in treating oral squamous cell carcinoma was discussed. METHODS: Twenty-seven cN0 patients with oral squamous cell carcinoma were entered into the study. Supraomohyoid neck dissection was performed to remove the lymphatic tissue of level I, II, and III. The operation duration and shoulder function were recorded. RESULTS: The average operation duration was (1.6 +/- 0.2) h. Nineteen percent (5/27) of the cN0 neck were proved positive pathologically which included two cases in level I and four in level II (one case had both level I and II metastases). Shoulder function recovered in three months after operation. All patients were followed up from two years to four years and none of them had local or neck recurrence. CONCLUSIONS: Supraomohyoid neck dissection is a right choice for cN0 patients with oral squamous cell carcinoma with its advantages in both curing neck lymphatic metastases and preserving neck and shoulder contours and functions.

Adult↗

PubMed2005

[Study on transformation of P-dissolving Penicillium oxalicum P8 with double-marker vector expressing green fluorescent protein and hygromycin B resistance].

P-dissolving Penicillium oxalicum P8 was isolated previously in this lab which has a considerable ability to dissolve many kinds of inorganic phosphorus and improve crop growth. In order to study rhizosphere colonization of plants by Penicillium oxalicum P8, protoplasts were transformed with a double-marker expression vector of green fluorescent protein and hygromycin B resistance. Some transformants were selected which expressed both the GFP and hygromycin B phosphotransferase and did not show significant morphological or physiological differences as compared to wild-type strain. Southern blot analysis confirmed the heterogeneous genomic integration of the vector DNA into the transformants.

Anti-Bacterial Agents↗

PubMed2005

[Effect of pollutants of press-pack industry on antioxidants level of worker].

OBJECTIVE: To study the differences in antioxidants level (SOD, GSH-PX, LPO, VC, VE) between the male workers who worked to volatile benzene compounds in printing factory and the male workers who were not for evaluating the effect of pollution of volatile benzene compounds in printing industry. METHODS: SOD, GSH-PX, VC were measured as ultraviolet visible spetrophotometry (UV). LPO, V(E) were measured as molecular fluorescence spectroscopy. Data of 43 male workers exposed to benzene toluene and xylene and control group of 50 were analyzed by SPSS 11.0. RESULTS: The exposed workers were significantly different with controls in SOD, GSH-PX/LPO, VC (P < 0.05) but not in VE (P > 0.05). CONCLUSION: The Antioxidants level of male printing workers could be affected by exposure to pollution of volatile benzene compounds in printing industry.

Adult↗

PubMed2005

[A randomized clinical trial on comparison of weight-adjusted dose with low dose recombinant tissue-type plasminogen activator on Chinese patients with acute myocardial infarction].

OBJECTIVE: The aim of the study was to quest appropriate dose of recombinant tissue-type plasminogen activator (rt-PA) on Chinese patients with acute myocardial infarction. METHODS: All enrolled patients were randomized into weight-adjusted dose or low dose rt-PA group, and received a basal treatment with aspirin and heparin. Additionally, after an intravenous bolus of 8 mg rt-PA, patients in weight-adjusted dose group (n = 93) were given an intravenous infusion of 42-92 mg rt-PA (1 mg/kg body weight), while patients in the low dose group (n = 91) were treated with an intravenous infusion of 42 mg rt-PA over 90 minutes. The observational endpoint included reperfusion rate of the infarct-related artery by clinical criteria, left ventricular ejection fraction and major adverse cardiovascular events within 30 days in the two groups. RESULTS: There were 74 patients diagnosed reperfusion by clinical criteria in weight-adjusted dose group and 59 patients in low dose group (79.6% vs 64.8%, P = 0.026). The left ventricular ejection fraction seemed to be better in weight-adjusted dose group than in low dose group (P = 0.259). The major adverse cardiovascular events within 30 days were less in weight-adjusted dose group than in low dose group (P < 0.05). CONCLUSION: There was statistical significant superiority of weight-adjusted dose over low dose rt-PA in the treatment of Chinese patients with acute myocardial infarction.

Adult↗

PubMed2004

Attachment of gold nanoparticles to glassy carbon electrode and its application for the direct electrochemistry and electrocatalytic behavior of hemoglobin.

Gold nanoparticles have been attached onto glassy carbon electrode surface through sulfhydryl-terminated monolayer and characterized by X-ray photoelectron spectroscopy, atomic force microscopy, electrochemical impedance spectroscopy and cyclic voltammetry. The gold nanoparticles-attached glassy carbon electrodes have been applied to the immobilization/adsorption of hemoglobin, with a monolayer surface coverage of about 2.1 x 10(-10) mol cm(-2), and consequently obtained the direct electrochemistry of hemoglobin. Gold nanoparticles, acting as a bridge of electron transfer, can greatly promote the direct electron transfer between hemoglobin and the modified glassy carbon electrode without the aid of any electron mediator. In phosphate buffer solution with pH 6.8, hemoglobin shows a pair of well-defined redox waves with formal potential (E0') of about -0.085 V (versus Ag/AgCl/saturated KCl). The immobilized hemoglobin maintained its biological activity, showing a surface controlled electrode process with the apparent heterogeneous electron transfer rate constant (ks) of 1.05 s(-1) and charge-transfer coefficient (a) of 0.46, and displays the features of a peroxidase in the electrocatalytic reduction of hydrogen peroxide. A potential application of the hemoglobin-immobilized gold nanoparticles modified glassy carbon electrode as a biosensor to monitor hydrogen peroxide has been investigated. The steady-state current response increases linearly with hydrogen peroxide concentration from 2.0 x 10(-6) to 2.4 x 10(-4) M. The detection limit (3sigma) for hydrogen peroxide is 9.1 x 10(-7) M.

Biosensing Techniques↗

PubMed2004

Evidence that TRPM8 is an androgen-dependent Ca2+ channel required for the survival of prostate cancer cells.

The Ca(2+)-permeable channel TRPM8 is thought to play an important role in the pathophysiology of prostate cancer. We have investigated the intracellular location of TRPM8 and its role as a Ca(2+)-permeable channel in an androgen-responsive and an androgen-insensitive prostate cancer cell line. We report evidence from immunofluorescence experiments that in the androgen-responsive LNCaP cell line, the TRPM8 protein is expressed in the endoplasmic reticulum and plasma membrane, acts as a Ca(2+)-permeable channel (assessed using Fura-2 to measure increases in the cytoplasmic Ca(2+) concentration) in each of these membranes, and is regulated by androgen. Although TRPM8 was detected in the androgen-insensitive PC-3 cell line, no evidence was obtained for regulation of its expression by androgen. The results of experiments using LNCaP cells, the TRPM8 antagonist capsazepine, and small interference RNA targeted to TRPM8 indicate that TRPM8 is required for cell survival. These results indicate that TRPM8 is an important determinator of Ca(2+) homeostasis in prostate epithelial cells and may be a potential target for the action of drugs in the management of prostate cancer.

Androgens↗

PubMed2004

Experimental observation of true left-handed transmission peaks in metamaterials.

We report true left-handed (LH) behavior in a composite metamaterial consisting of a periodically arranged split ring resonator (SRR) and wire structures. We demonstrate the magnetic resonance of the SRR structure by comparing the transmission spectra of SRRs with those of closed SRRs. We have confirmed experimentally that the effective plasma frequency of the LH material composed of SRRs and wires is lower than the plasma frequency of the wires. A well-defined LH transmission band with a peak value of -1.2 dB (-0.3 dB/cm) was obtained. The experimental results agree extremely well with the theoretical calculations.

Journal Article↗

PubMed2004

Conditioning lesions enhance axonal regeneration of descending brain neurons in spinal-cord-transected larval lamprey.

In larval lamprey, with increasing recovery times after a transection of the rostral spinal cord, there is a gradual recovery of locomotor behavior, and descending brain neurons regenerate their axons for progressively greater distances below the transection site. In the present study, spinal cord "conditioning lesions" (i.e., transections) were performed in the spinal cord at 30% body length (BL; normalized distance from the head) or 50% BL. After various "lesion delay times" (D), a more proximal spinal cord "test lesion" (i.e., transection) was performed at 10% BL, and then, after various recovery times (R), horseradish peroxidase was applied to the spinal cord at 20% BL to determine the extent of axonal regeneration of descending brain neurons. Conditioning lesions at 30% BL, lesion delay times of 2 weeks, and recovery times of 4 weeks (D-R = 2-4 group) resulted in a significant enhancement of axonal regeneration for the total numbers of descending brain neurons as well as neurons in certain brain cell groups compared to control animals without conditioning lesions. Experiments with hemiconditioning lesions, which reduce interanimal variability, confirmed that conditioning lesions do significantly enhance axonal regeneration and indicate that axotomy rather than diffusible factors released at the injury site is primarily involved in this enhancement. Results from the present study suggest that conditioning lesions "prime" descending brain neurons via cell body responses and enhance subsequent axonal regeneration, probably by reducing the initial delay and/or increasing the initial rate of axonal outgrowth.

Animals↗

PubMed2004

A comparative proteomic strategy for subcellular proteome research: ICAT approach coupled with bioinformatics prediction to ascertain rat liver mitochondrial proteins and indication of mitochondrial localization for catalase.

Subcellular proteomics, as an important step to functional proteomics, has been a focus in proteomic research. However, the co-purification of "contaminating" proteins has been the major problem in all the subcellular proteomic research including all kinds of mitochondrial proteome research. It is often difficult to conclude whether these "contaminants" represent true endogenous partners or artificial associations induced by cell disruption or incomplete purification. To solve such a problem, we applied a high-throughput comparative proteome experimental strategy, ICAT approach performed with two-dimensional LC-MS/MS analysis, coupled with combinational usage of different bioinformatics tools, to study the proteome of rat liver mitochondria prepared with traditional centrifugation (CM) or further purified with a Nycodenz gradient (PM). A total of 169 proteins were identified and quantified convincingly in the ICAT analysis, in which 90 proteins have an ICAT ratio of PM:CM>1.0, while another 79 proteins have an ICAT ratio of PM:CM<1.0. Almost all the proteins annotated as mitochondrial according to Swiss-Prot annotation, bioinformatics prediction, and literature reports have a ratio of PM:CM>1.0, while proteins annotated as extracellular or secreted, cytoplasmic, endoplasmic reticulum, ribosomal, and so on have a ratio of PM:CM<1.0. Catalase and AP endonuclease 1, which have been known as peroxisomal and nuclear, respectively, have shown a ratio of PM:CM>1.0, confirming the reports about their mitochondrial location. Moreover, the 125 proteins with subcellular location annotation have been used as a testing dataset to evaluate the efficiency for ascertaining mitochondrial proteins by ICAT analysis and the bioinformatics tools such as PSORT, TargetP, SubLoc, MitoProt, and Predotar. The results indicated that ICAT analysis coupled with combinational usage of different bioinformatics tools could effectively ascertain mitochondrial proteins and distinguish contaminant proteins and even multilocation proteins. Using such a strategy, many novel proteins, known proteins without subcellular location annotation, and even known proteins that have been annotated as other locations have been strongly indicated for their mitochondrial location.

Animals↗

PubMed2004

Study of mixtures of n-dodecyl-beta-D-maltoside with anionic, cationic, and nonionic surfactant in aqueous solutions using surface tension and fluorescence techniques.

Surfactants of practical interest are invariably mixtures of different types. In this study, mixtures of sugar-based n-dodecyl-beta-D-maltoside with cationic dodecyltrimethylammonium bromide, anionic sodium dodecylsulfate, and nonionic pentaethyleneglycol monododecyl ether in solution, with and without supporting electrolyte, have been studied using surface tension and fluorescence spectroscopic techniques. Interaction parameters and mole fraction of components in mixed micelles were calculated using regular solution theory. The magnitude of interactions between n-dodecyl-beta-D-maltoside and other surfactants followed the order anionic/nonionic > cationic/nonionic > nonionic/nonionic mixtures. Since all surfactants have the same hydrophobic groups, strengths of interactions are attributed to the structures of hydrophilic headgroups. Electrolyte reduced synergism between n-dodecyl-beta-D-maltoside and ionic surfactant due to charge neutralization. Industrial sugar-based surfactant, dodecyl polyglucoside, yielded results similar to that with dodecyl maltoside, implying that tested commercial alkyl polyglucosides are similar to the pure laboratory samples in synergistic interactions with other surfactants. Fluorescence study not only supported the cmc results using tensiometry, but showed that interfaces of all the above mixed micelle/solution interfaces are mildly hydrophobic. Based on these results, an attempt is made to discover the nature of interactions to be a combination of intermolecular potential energies and free energy due to packing of surfactant molecules in micelles.

Anions↗

PubMed2004

Minocycline protects PC12 cells from ischemic-like injury and inhibits 5-lipoxygenase activation.

Minocycline protects animals against cerebral ischemia by inhibiting inflammation. To determine whether minocycline protects PC12 cells from in vitro ischemic-like injury and affects pro-inflammatory 5-lipoxygenase activation, the cell viability and 5-lipoxygenase translocation to nuclear membrane were observed after oxygen-glucose deprivation (OGD). We found that OGD reduced cell viability, which was attenuated by minocycline and 5-lipoxygenase inhibitor caffeic acid. 5-Lipoxygenase protein was detected in PC12 cells by immunohistochemical and Western blot analyses. OGD induced 5-lipoxygenase translocation to nuclear membranes, which was abolished by minocycline and caffeic acid. Thus, minocycline can protect PC12 cells from in vitro ischemic-like injury, and this effect may be partly related to the inhibition of 5-lipoxygenase activation.

Animals↗

PubMed2004

van der Waals interaction between internal aqueous droplets and the external aqueous phase in double emulsions.

A mathematical model for analyzing the van der Waals interaction between the internal aqueous droplets (W(1)) and the external aqueous phase (W(2)) of double emulsions has been established. The effects of Hamaker constants of the materials forming the system, especially those of the two different adsorbed surfactant layers with uniform density (A(1) and A(2)), on the van der Waals interaction were investigated. The overall van der Waals interaction across the oil film is a combined result of four individual parts, that is, W(1)-W(2), A(1)-A(2), W(1)-A(1), and A(2)-W(2) van der Waals interaction, and it may be either attractive or repulsive depending on many factors. It was found that the overall van der Waals interaction is dominated by the W(1)-W(2) interaction at large separation distances between the W(1)/O and O/W(2) interfaces, while it is mostly determined by the A(1)-A(2) interaction when the two interfaces are extremely close. Specifically, in the cases when the value of the Hamaker constant of the oil phase is intermediate between those of W(1) and W(2) and there is a thick oil film separating the two interfaces, a weak repulsive overall van der Waals interaction will prevail. If the Hamaker constant of the oil phase is intermediate between those of A(1) and A(2) and the two interfaces are very close, the overall van der Waals interaction will be dominated by the strong repulsive A(1)-A(2) interaction. The repulsive van der Waals interaction at such cases helps stabilize the double emulsions.

Emulsions↗

PubMed2004

Stress response inhibits the nephrotoxicity of cisplatin.

Salt loading and saline hydration are used to protect patients from cisplatin-induced nephrotoxicity. The mechanism by which salt exerts its protective effect is unknown. As part of an ongoing study of cisplatin nephrotoxicity, an in vitro assay system was developed that models the in vivo exposure and response of proximal tubule cells to cisplatin. In this study, it was discovered that the toxicity of cisplatin toward LLC-PK(1) cells varied dramatically according to the tissue culture media used for 3-h cisplatin exposure. Further experiments revealed that minor variations in the sodium concentration among standard tissue culture media modulated cisplatin nephrotoxicity. NaCl has been shown to protect against cisplatin-induced nephrotoxicity in vivo but has never before been demonstrated in vitro. NaCl did not alter the cellular accumulation of cisplatin. NaCl altered the osmolarity of the external media, and its effect was replicated by substituting equiosmolar concentrations of impermeant anions or cations. The change in osmolarity triggered a stress response within the cell that modulated sensitivity to cisplatin. These data resolve several long-standing controversies regarding the mechanism by which salt loading protects the kidney from cisplatin-induced nephrotoxicity.

Animals↗

PubMed2004

pH-dependent conformational changes of ferricytochrome c induced by electrode surface microstructure.

pH-dependent processes of bovine heart ferricytochrome c have been investigated by electronic absorption and circular dichroism (CD) spectra at functionalized single-wall carbon nanotubes (SWNTs) modified glass carbon electrode (SWNTs/GCE) using a long optical path thin layer cell. These methods enabled the pH-dependent conformational changes arising from the heme structure change to be monitored. The spectra obtained at functionalized SWNTs/GCE reflect electrode surface microstructure-dependent changes for pH-induced protein conformation, pK(a) of alkaline transition and structural microenvironment of the ferricytochrome c heme. pH-dependent conformational distribution curves of ferricytochrome c obtained by analysis of in situ CD spectra using singular value decomposition least square (SVDLS) method show that the functionalized SWNTs can retain native conformational stability of ferricytochrome c during alkaline transition.

Animals↗

PubMed2004

Characterization of the 3a protein of SARS-associated coronavirus in infected vero E6 cells and SARS patients.

Proteomics was used to identify a protein encoded by ORF 3a in a SARS-associated coronavirus (SARS-CoV). Immuno-blotting revealed that interchain disulfide bonds might be formed between this protein and the spike protein. ELISA indicated that sera from SARS patients have significant positive reactions with synthesized peptides derived from the 3a protein. These results are concordant with that of a spike protein-derived peptide. A tendency exists for co-mutation between the 3a protein and the spike protein of SARS-CoV isolates, suggesting that the function of the 3a protein correlates with the spike protein. Taken together, the 3a protein might be tightly correlated to the spike protein in the SARS-CoV functions. The 3a protein may serve as a new clinical marker or drug target for SARS treatment.

Animals↗