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Biomedical subjects

Wei He

Publications and source records attributed to Wei He.

193 records · Page 11Linked to original sources
PubMed2002

[Culture and identification of dendritic cells from the peripheral blood of patients with laryngeal squamous cell carcinoma in vitro].

OBJECTIVE: To culture dendritic cells (DC) from peripheral blood of patients with laryngeal carcinoma for therapeutic aid. METHODS: Adherent peripheral blood mononuclear cells from peripheral blood were cultured with 15 ng/ml rhGM-CSF and 7 ng/ml rhIL-4 for one or two weeks. The purity of DC was detected by immunocytochemistry method. The mixed leukocyte reactions stimulated by DC loaded with laryngeal carcinoma antigen were tested by measuring 3H-TdR uptake. RESULTS: A considerable number of suspended cells with spicular or dendritic appearance were observed after 1 week of culture, and their mitochondria were rich in cytoplasm. The positivity of DC was about 30%-60%. DC loaded with laryngeal antigen could induce proliferation of syngeneic T lymphocytes. CONCLUSION: A large number of DC with high purity can be cultured from peripheral blood of patients with laryngeal carcinoma in vitro. It may be used in further experimental studies for clinical applications.

Carcinoma, Squamous Cell↗
PubMed2002

[NK cell receptors and related ligands].

NK cell has antigen-non-specific receptors on its surface. Based on the molecular structure, NK cell receptors can be divided into two types, including Ig superfamily and C-type lectin superfamily. Based on function, NK cell receptors can be divided into activation receptors (NKAR) and inhibition receptors (NKIR). NKAR includes CD16 mediating antibody dependent cytotoxicity, NKR-P1 mediating natural cytotoxicity, KAR conjugated with DAP12 and co-stimulatory receptor. They transduce signal through the ITAM motif in their cytoplasmic region. NKIR mainly include KIR and CD94/NKG2. Their ligands are MHC-I molecules. They are closely related to the recognition of auto cells by NK cells. Inhibition of NKAR activation and cytotoxic effect of NK cells by NKIR are carried out through the ITIM motif and require co-aggregation of NKAR and NKIR.

Antigens, CD↗
PubMed2002

[Positive and negative selection of thymocytes].

Maturation of T cells in thymus plays key roles in antigen-specific immune response. In maturation, thymocytes undergo positive and negative selection. The MHC restriction of T cell is determined in positive selection. The tolerance of T cells to autoantigen is acquired during negative selection. Quantitation (avidity) theory points out that difference of avidity between thymocytes and stroma cells leads to difference in the signals integrated inside cells. When the signal reaches a particular threshold, positive or negative selection takes place. In this article, the selection mechanism and the relationship between positive and negative selection are mini-reviewed.

Animals↗
PubMed2002

[Progress in the study on the molecules in CD28 family].

CD28 family consists of CD28, ICOS, CTLA-4 and PD-1 molecules. The former two are activation receptors and the later two are inhibition receptors. They produce co-stimulatory signals combining with the relevant molecules in B7 family, which plays important role in T cell activation and homeostasis among T subsets. Although the mechanism of signaling by CD28 and CTLA-4 has been well studied, many questions still remain to be answered. Further investigations are required for substantiating the dual-signaling model.

Animals↗
PubMed2000

Structure of a New Glucan from Cynanchum panilatum (Bunge) Kitagawa.

A polysaccharide was purified from a traditional Chinese drug, "Xu-Chang-Qing" (Cynanchum panilatum (Bunge) Kitagawa), and its molecular weight was estimated to be 1.5x10(4) by HPLC method. Its specific rotation [alpha](D) was 151.4 deg; (0.96, H(2)O). Sugar composition analysis indicated this polysaccharide was composed only of glucose. Methylation analysis, partially hydrolysis, acetolysis, IR and NMR data showed that its main chain was composed of alpha-D 1,4 linked glucosyl residues and its side chains were composed of alpha-D 1,4 and alpha-D 1,6 linked glucosyl residues. There was one branch located at O-6 of the glucosyl residue in every repeating unit containing five-glucosyl residues.

Journal Article↗
PubMedDate not supplied

Tc-99m tetrofosmin tomography after nitrate administration in patients with ischemic left ventricular dysfunction: relation to metabolic imaging by PET.

BACKGROUND: In patients with ischemic left ventricular (LV) dysfunction, myocardial perfusion imaging after nitrate administration may improve the identification of dysfunctional but viable myocardium. This study was designed to assess the relationship between tetrofosmin uptake after nitrate administration and metabolic activity as assessed by positron emission tomography (PET) in patients with ischemic LV dysfunction. METHODS AND RESULTS: Thirty-six patients with chronic myocardial infarction and LV dysfunction (ejection fraction, 35% +/- 6%) underwent resting technetium 99m tetrofosmin single photon emission computed tomography (SPECT) imaging under control conditions (baseline) and after sublingual administration of 10 mg isosorbide dinitrate. Within 1 week, all patients underwent metabolic PET imaging with fluorine 18-fluorodeoxyglucose. Tetrofosmin uptake and metabolic activity were measured in 13 segments/patient. Regional LV function was assessed in corresponding segments by echocardiography. On baseline tetrofosmin imaging, 53 (40%) of the 131 akinetic or dyskinetic segments had reduced (<55% of peak activity) tracer uptake. Of these segments, 14 (26%) showed enhanced tetrofosmin uptake after nitrate administration (>/=10% vs baseline) and the remaining 38 (74%) did not change. The sensitivity and specificity of baseline tetrofosmin SPECT for detecting preserved metabolic activity were 69% and 86%, respectively. After nitrate administration, the sensitivity was higher (81%, P <.05 vs baseline) whereas the specificity was not different (86%, P = not significant). Concordance between tetrofosmin SPECT and PET in differentiating viable and necrotic myocardium was observed in 94 (72%) of the 131 akinetic or dyskinetic segments at baseline (kappa = 0.35) and in 108 segments (82%) after nitrate administration (kappa = 0.53). CONCLUSIONS: After nitrate administration, tetrofosmin uptake in dysfunctional segments correlated with metabolic activity as assessed by fluorodeoxyglucose PET imaging better than baseline. Thus tetrofosmin SPECT after nitrate administration may improve the identification of ischemic but still viable myocardium in patients with chronic ischemic LV dysfunction.

Adult↗
PubMedDate not supplied

Synthesis, characterization, and preliminary biological study of poly(3-(tert-butoxycarbonyl)-N-vinyl-2-pyrrolidone).

Poly(3-(tert-butoxycarbonyl)-N-vinyl-2-pyrrolidone) has been synthesized and characterized by gel permeation chromatography, Fourier transform infrared spectroscopy, NMR spectroscopy, and thermal analysis. The polymer is a chemically amplified photoresist. Arrays of lines with 25 microm width and 25 microm spacing were successfully patterned with this polymer by photolithography. Rat fibroblast cells were seeded on these patterned surfaces as well as the smooth glass surface. Phase contrast microscopy showed that cells on the patterned surfaces were strongly aligned and elongated along the grooves as compared to randomly spreading on the smooth surface. Since controlling cell orientation is critical for the development of advanced forms of tissue repair and cell engineering therapies, for example, peripheral nerve repair, production of tendon and ligament substitutes in vitro, and control of microvascular repair, the described polymer may be useful for applications in tissue reconstruction.

Animals↗
PubMedDate not supplied

Screening and identification of linear B-cell epitopes and entry-blocking peptide of severe acute respiratory syndrome (SARS)-associated coronavirus using synthetic overlapping peptide library.

A 10-mer overlapping peptide library has been synthesized for screening and identification of linear B-cell epitopes of severe acute respiratory syndrome associated coronavirus (SARS-CoV), which spanned the major structural proteins of SARS-CoV. One hundred and eleven candidate peptides were positive according to the result of PEPscan, which were assembled into 22 longer peptides. Five of these peptides showed high cross-immunoreactivities (approximately 66.7 to 90.5%) to SARS convalescent patients' sera from the severest epidemic regions of the China mainland. Most interestingly, S(471-503), a peptide located at the receptor binding domain (RBD) of SARS-CoV, could specifically block the binding between the RBD and angiotensin-converting enzyme 2, resulting in the inhibition of SARS-CoV entrance into host cells in vitro. The study demonstrated that S(471-503) peptide was a potential immunoantigen for the development of peptide-based vaccine or a candidate for further drug evaluation against the SARS-CoV virus-cell fusion.

Amino Acid Sequence↗
PubMedDate not supplied

Fabrication and endothelialization of collagen-blended biodegradable polymer nanofibers: potential vascular graft for blood vessel tissue engineering.

Electrospun collagen-blended poly(L-lactic acid)-co-poly(epsilon-caprolactone) [P(LLA-CL), 70:30] nanofiber may have great potential application in tissue engineering because it mimicks the extracellular matrix (ECM) both morphologically and chemically. Blended nanofibers with various weight ratios of polymer to collagen were fabricated by electrospinning. The appearance of the blended nanofibers was investigated by scanning electron microscopy and transmission electron microscopy. The nanofibers exhibited a smooth surface and a narrow diameter distribution, with 60% of the nanofibers having diameters between 100 and 200 nm. Attenuated total reflectance-Fourier transform infrared spectra and X-ray photoelectron spectroscopy verified the existence of collagen molecules on the surface of nanofibers. Human coronary artery endothelial cells (HCAECs) were seeded onto the blended nanofibers for viability, morphogenesis, attachment, and phenotypic studies. Five characteristic endothelial cell (EC) markers, including four types of cell adhesion molecule and one EC-preferential gene (von Willebrand factor), were studied by reverse transcription-polymerase chain reaction. Results showed that the collagen-blended polymer nanofibers could enhance the viability, spreading, and attachment of HCAECs and, moreover, preserve the EC phenotype. The blending electrospinning technique shows potential in refining the composition of polymer nanofibers by adding various ingredients (e.g., growth factors) according to cell types to fabricate tissue-engineering scaffold, particularly blood vessel-engineering scaffold.

Biocompatible Materials↗