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Biomedical subjects

P Qiu

Publications and source records attributed to P Qiu.

At least 19 recordsLinked to original sources
PubMed2006

Optophysiology: depth-resolved probing of retinal physiology with functional ultrahigh-resolution optical coherence tomography.

Noncontact, depth-resolved, optical probing of retinal response to visual stimulation with a <10-microm spatial resolution, achieved by using functional ultrahigh-resolution optical coherence tomography (fUHROCT), is demonstrated in isolated rabbit retinas. The method takes advantage of the fact that physiological changes in dark-adapted retinas caused by light stimulation can result in local variation of the tissue reflectivity. fUHROCT scans were acquired from isolated retinas synchronously with electrical recordings before, during, and after light stimulation. Pronounced stimulus-related changes in the retinal reflectivity profile were observed in the inner/outer segments of the photoreceptor layer and the plexiform layers. Control experiments (e.g., dark adaptation vs. light stimulation), pharmacological inhibition of photoreceptor function, and synaptic transmission to the inner retina confirmed that the origin of the observed optical changes is the altered physiological state of the retina evoked by the light stimulus. We have demonstrated that fUHROCT allows for simultaneous, noninvasive probing of both retinal morphology and function, which could significantly improve the early diagnosis of various ophthalmic pathologies and could lead to better understanding of pathogenesis.

Animals↗
PubMed2004

Identification of single-nucleotide polymorphisms of the human neurokinin 1 receptor gene and pharmacological characterization of a Y192H variant.

Neurokinin receptors in the central nervous system are involved in the neural circuitry of anxiety, depression and emesis. This has led to the development of nonpeptidic NK1 receptor antagonists as therapeutic agents. Clinical trials have shown that NK1 receptor antagonists have efficacy in chemotherapy-induced emesis and depression. Sequence polymorphisms can potentially influence the efficacy of drugs in patient populations and are an important consideration in the drug development process. To identify DNA sequence variants in the NK1 receptor, comparative DNA sequencing was performed on a population of 93 individuals. In total, 19 single-nucleotide polymorphisms (SNPs) were identified with one SNP (g.78351T>C) resulting in a tyrosine to histidine substitution at residue 192 (Y192H). The Y192H variant was expressed using site-directed mutagenesis and was characterized with respect to affinity, receptor kinetics, functional calcium response and receptor internalization. In all cases the Y192H variant was found to display properties similar to those of the wild-type receptor.

Alleles↗
PubMed2001

Analyses of p53 target genes in the human genome by bioinformatic and microarray approaches.

The completion of the human genome sequence (International Human Genome Sequence Consortium (2001) Nature 409, 860-921; Venter, J. C., et al. (2001) Science 291, 1304-1351) allows for new ways to analyze global cellular regulatory mechanisms. Here we present a strategy to identify genes regulated by specific transcription factors in the human genome, and apply it to p53. We first collected promoters or introns of all genes available using two methods: GenBank(TM) annotation and a computationally derived transcript map. 4,852 genes analyzed in this way contained at least one p53 consensus binding sequence. Of 13 genes randomly selected for mRNA analysis, 11 were shown to respond to p53 expression. Five promoters were analyzed by chromatin immunoprecipitation, which revealed that all were bound by p53 in vivo. We then analyzed 33,615 unique human genes on cDNA microarrays, identifying 1,501 genes that respond to p53 expression. A parameter was derived that demonstrates that in silico prediction greatly enriches for genes that are activated and repressed by p53 and assists us to suggest other signaling pathways that may be connected to p53. The methods shown here illustrate a novel approach to analysis of global gene regulatory network through the integration of human genomic sequence information and genome-wide gene expression analysis.

Computational Biology↗
PubMed2000

Sample size to test for interaction between a specific exposure and a second risk factor in a pair-matched case-control study.

We discuss a sample size calculation for a pair-matched case-control study to test for interaction between a specific exposure and a second risk factor. The second risk factor could be either binary or continuous. An algorithm for the calculation of sample size is suggested which is based on a logistic regression model that relates the logarithm of the disease-exposure odds ratio to the second risk factor. This problem is motivated by a study comparing the prevalence of GP-IIIa Pl(A2) polymorphism (the exposure) in individuals with and without myocardial infarction (case-control). One of the hypotheses in this study is whether or not there is an interaction between the prevalence of GP-IIIa Pl(A2) polymorphism and a second risk factor such as smoking status and homocysteine level. We introduce the algorithm in detail with several numerical examples.

Algorithms↗
PubMed1999

Differential regulation of transcription termination occurring at two different sites on the micro-delta gene complex.

The progression of polymerases across the micro-delta Ig heavy chain gene complex is characterized by two termination events occurring at different sites on the transcription unit and at different times during B cell differentiation. We have utilized two mouse strains to analyze the regulatory determinants for these events in primary B cells. In the transgenic pmicro.microdeltaRatt strain a 1160 bp intervening DNA segment (the att site) has been inverted. This mutation results in the abrogation of transcription termination that occurs in early B cells. Using a novel method that takes advantage of an internal ribosome entry site we have further restricted the size of the segment that is needed for inducing transcription termination in transfectants. This 200 bp termination-inducing sequence operates in tumor equivalents of early but not mature B cells and the activity is correlated with differential binding of nuclear proteins. To explore the regulatory basis for the change in site of transcription termination upon B cell activation we have examined the microS-/- deletion mutant strain in which the microS poly(A) site has been eliminated. The results suggest that polyadenylation at the microS site plays a dominant but not exclusive role in regulating transcription termination in activated B cells.

Animals↗
PubMed1999

Modeling daily and subdaily cycles in rat sleep data.

We developed a statistical model for rat sleep-wake behavior over the 24-hour day; this model could be used for animals exposed to shorter cycles of light and dark conditions. Rat behavior was classified either as "wake" or "sleep," as determined by analysis of electrophysiological data. The proposed model consists of three parts: the first two explain cyclic effects relating to the lighting conditions, whereas the last part reflects any acyclic effect. Hypothesis tests were conducted on the magnitude of the parts. The model also accounts for correlated errors.

Activity Cycles↗
PubMed1999

[The experimental research of purification and character of cultured retinal ganglion cell].

OBJECTIVE: To establish a cell line and purification model of retinal ganglion cells (RGCs) in vitro. METHOD: RGCs from Sprague Dawley neonatal rats (postnatal 1 - 3 days) were cultured in basal medium eagle (BME) basal medium. The growth regularity of RGCs in vitro was observed under phase-contrast microscope. RGCs were purified by Thy 1.1 with FITC antibody and detected under fluorescent microscope and phase-contrast microscope. RESULTS: Higher density of retinal cells and tectal extract facilitate cultured RGCs to survive. The purification rate of retinal ganglion cells in the experiment arrived at 95 percent. CONCLUSION: Cytokine and trophic factors from other cells in the retina and tectal extract can promote RGCs to survive, and they can be purified by Thy 1.1 antibody.

Animals↗
PubMed1999

[Extraction and purification of acidic mucopolysaccharide from Holothuria atra].

Mucopolyaccharide with molecular weight of 10253 Da was extracted and purified from fresh Holothuria atra Jaeger by means of enzymic and alkaline hydrolysis, potassium acetate and ethanol fractional precipitation. It was tested to be purified ingredient with agarose electrophoresis. The percentage content of galactosamine, glucuronic acid, fucose and sulfate in the mucopolysaccharide was 16.12%, 17.88%, 11.66% and 23.52% respectively.

Animals↗
PubMed1999

[Effect of N-methyl-D-aspartate and dexamethasone on apoptosis of rat cultured retinal ganglion cells].

PURPOSE: To investigate the effect of N-methyl-D-aspartate(NMDA) and Dexamethasone on cultured rat retinal ganglion cells (RGCS). METHODS: RGCs were obtained from 1-3 days old SD rats. In two groups, exposure of cocultured ganglion cells to N-methyl-D-aspartate (20-500 mumol/L) lasted for 24 hours. Apoptotic cells were identified by Hochest 33258 in one group; In another group, 0.4% Trypan blue dye was added. Cells excluding the dye were counted, and the survival rate of cells was determined by the ratio of the excluding cells in the experiment over in the control; Cocultured RGCs and purified RGCs were exposed to Dexamethasone(1 x 10(-4), 1 x 10(-5) and 1 x 10(-6) mol/L). After 24 hours, apoptotic cells were identified by Hochest33258. RESULT: Cocultured RGCs showed distinct morphological appearance of apoptotic cells when they were exposed to NMDA. The survival rate of cells was dose-related to the concentration of NMDA. Cocultured RGCs didn't show typical apoptotic appearance at 24 hours after exposure to Dexamethasone. But purified RGCs did so, even in the control group. CONCLUSION: NMDA has the effect of inducing cocultured RGCs apoptosis. Dexamethasone had no this effect on RGCs. Without additional neurotrophic factors, purified RGCs may become apoptotic cells when cultured in vitro for 24 hours.

Animals↗
PubMed1998

Cytokine transgene expression and promoter usage in primary CD34+ cells using particle-mediated gene delivery.

Induction or short-term transgenic expression of specific cytokines, growth factors, or other candidate therapeutic genes in hematopoietic progenitor or stem cells is potentially applicable to gene therapy for cancer. In this study, we explored the application of a gene gun technique, as an alternative to viral vectors, for ex vivo gene transfer into and transient gene expression in highly enriched CD34+ cells derived from human umbilical cord blood. Twenty-four hours posttransfection, 32.6 to 1500 pg/l x 10(6) CD34+ cells of transient gene expression was routinely obtained for specific cytokine and reporter genes. Transgene expression at the single-cell level was revealed by X-Gal staining of lacZ cDNA-transfected CD34+ cells. Expression of four candidate therapeutic genes, namely human granulocyte-macrophage colony-stimulating factor, tumor necrosis factor alpha, interleukin 2, and interferon gamma, was detectable for 4 to 7 days in CD34+ cells. A human elongation factor 1alpha promoter/intron 1 transcription unit was identified as a strong cellular promoter for CD34+ cells, exhibiting strength similar to that of the commonly employed cytomegalovirus immediate-early promoter. These results suggest that the nonviral, gene gun technique offers an efficient alternative approach for transient transgenic studies of hematopoietic cells and may provide new possibilities for certain cancer gene therapy strategies using CD34+ cells.

Antigens, CD34↗
PubMed1998

A role for the Drosophila Toll/Cactus pathway in larval hematopoiesis.

In the Drosophila larva, blood cells or hemocytes are formed in the lymph gland. The major blood cell type, called plasmatocyte, is small, non-adhesive and phagocytic. Plasmatocytes differentiate into adhesive lamellocytes to form multilayered capsules around foreign substances or, in mutant melanotic tumor strains, around self tissue. Mutations in cactus or Toll, or constitutive expression of dorsal can induce lamellocyte differentiation and cause the formation of melanotic capsules. As maternally encoded proteins, Toll, Cactus and Dorsal, along with Tube and Pelle, participate in a common signal transduction pathway to specify the embryonic dorsal-ventral axis. Using the maternal pathway as a paradigm, we investigated if these proteins have additional roles in larval hemocyte formation and differentiation. Analysis of cactus mutants that lack Cactus protein revealed that almost all of these animals have an overabundance of hemocytes, carry melanotic capsules and die before reaching pupal stages. In addition, the lymph glands of cactus larvae are considerably enlarged. The number of mitotic cells in the cactus and TollD hemolymph is higher than that in the wild-type hemolymph. The hemocyte density of mutant Toll, tube or pelle hemolymph is significantly lower than that of the wild type. Lethality of mutant cactus animals could be rescued either by the selective expression of wild-type Cactus protein in the larval lymph gland or by the introduction of mutations in Toll, tube or pelle. Cactus, Toll, Tube and Pelle proteins are expressed in the nascent hemocytes of the larval lymph gland. Our results suggest that the Toll/Cactus signal transduction pathway plays a significant role in regulating hemocyte proliferation and hemocyte density in the Drosophila larva. These findings are discussed in light of similar hematopoietic functions of Rel/I(kappa)B-family proteins in mice.

Animals↗
PubMed1998

[Investigation on sera prevalence rate of varicella and immunogenicity of varicella vaccine in healthy children].

A whole varicella virus antigen-ELISA method was used to investigate the sera prevalence rate of varicella in 315 healthy children aged 3-7 years. Results showed that the sera positive rate of anti-VZV-IgG was 41.6%. Different prevalence rates in different kindergartens were noticed, characterizing the differences of populations. Immunogenicity of Oka strain attenuated varicella vaccine among children was also studied. No obvious adverse reactions were observed and the seraconversion rate was 85.1%.

Antibodies, Viral↗
PubMed1998

[Study on human eye ciliary muscule cell culture and biologic characteristics].

PURPOSE: We cultured human ciliary muscle [HCM] cells to study their growth, ultrastructure, immunohistochemistry and functional characters. METHODS: HCM cells from 10 young donor eyes were cultured with collagenase IV digestion procedures in vitro, the cells were identified by eletronmicroscope and immunohistochemistry assay, their function were studied by single-cell-contraction assay. RESULTS: The cells were passed and grew in Hill-Valley pattern after conflunet; abundant filaments were presented under electronmicroscope. In Desmin protein immunohistochemistry study, the cultured cells were stained positive; in tissue sections, HCM cells stained positive, vascular smooth muscle stained positive weakly, but fibroblast cells and endothelial cells stained negative. 10(-3) M Carbachol could induce the cultured cells contract, this effect was antagonized by 10(-3) M Atropine. CONCLUSION: We successfully cultured HCM cells, which were able to contract.

Cells, Cultured↗
PubMed1997

A method for genome comparisons and hybridization studies using known megabase-scale DNA sequences as a reference.

We present a method for genome comparisons and high-resolution hybridization analyses using megabase stretches of known DNA sequences as a reference. The method employs two-dimensional gel electrophoresis, separating genomic segments cut with different restriction endonucleases in the first and second dimensions, to generate filters suitable for image analysis and repeated nucleic acid hybridizations. The corresponding two-dimensional pattern is computed from the reference nucleotide sequence and matched to the observed pattern, thereby identifying each fragment on the filter; at the same time the technique uncovers discrepancies from the reference sequence. This permits genome comparisons as well as automated identification and quantification of hybridization patterns with various probes. The technique is illustrated by an analysis of Saccharomyces cerevisiae chromosome IX.

Chromosome Walking↗
PubMed1996

Gene gun delivery of mRNA in situ results in efficient transgene expression and genetic immunization.

The use of mRNA to transfer genetic information into mammalian somatic cells in vivo or ex vivo may be advantageous in a number of gene therapy protocols. Success in utilizing in vivo RNA delivery for transgene expression has been extremely limited, partially due to RNA instability and to the lack of an efficient intracellular delivery mechanism applicable to a wide variety of tissue or organ systems. We report here that a particle-mediated gene delivery technology can be used to effectively deliver RNA molecules into a number of mammalian somatic tissue types. Expression from RNA transcripts of three reporter genes, firefly luciferase, human growth hormone and human alpha-1 antitrypsin, was detected in monolayer and suspension cell cultures bombarded in vitro, and in in vivo bombarded rat liver tissues, and mouse liver and epidermal tissues. Gene gun treatment of mouse epidermis in vivo with human alpha-1 antitrypsin messenger RNA elicited a strong, consistent antibody response which showed an increased titer with subsequent boosts. Results from this study point to future opportunities of applying RNA delivery techniques for transgenic studies, genetic vaccination, and gene therapy.

Animals↗
PubMed1995

Human macrophage colony stimulating factor (HM-CSF) expressed in baculovirus infected insect cells is biologically active in its monomeric form.

hM-CSF was reported to have biological activity only in a dimeric form. Using oligonucleotide-directed mutagenesis of hM-CSF (1-149aa) cDNA, we have substituted Ser31 for Cys31 which forms intermolecular disulfide bond in native hM-CSF. The mutant hM-CSF cDNA was expressed in insect BmN cells using baculovirus as a vector under the control of polyhedrin promoter. Biological activity analysis and radioligand receptor assay both showed that there was little difference between the mutant hM-CSF and the native dimeric hM-CSF. These results strongly support that the biologically active human M-CSF in its monomeric form can be expressed in recombinant baculovirus infected insect cells.

Animals↗
PubMed1995

Interaction of silkworm larvae expressed monomeric hM-CSF with its receptor on murine bone marrow derived macrophage.

Human macrophage colony-stimulating factor (hM-CSF) expressed in the silkworm larvae was monomeric. The nature of the interaction of iodinated monomeric M-CSF with murine bone marrow derived macrophage (BMM) was studied. On incubation with 2 nM [125I]M-CSF at 4 degrees C, approximately 90% of the maximal binding occurred within 15 min with a plateau around 1hr which then gradually declined. Scatchard plot analysis showed that the Kd for the monomeric M-CSF is 5.3 x 10(-10) M and the number of binding sites per cell is 4 x 10(4). Competition experiment indicated that cellular binding of the iodinated monomeric rhM-CSF was almost as effective as the native M-CSF. The results show that the interchain disulfide bond of M-CSF is not essential for the natural folding of active M-CSF.

Animals↗