Detection of preinvasive cancer cells.
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Carcinoma↗
Biomedical subjects
Q Zhang
Publications and source records attributed to Q Zhang.
The multitype zinc-finger protein U-shaped functions in heart cell specification in the Drosophila embryo.
Multitype zinc-finger proteins of the Friend of GATA/U-shaped (Ush) class function as transcriptional regulators of gene expression through their modulation of GATA factor activity. To better understand intrinsic properties of these proteins, we investigated the expression and function of the ush gene during Drosophila embryogenesis. ush is dynamically expressed in the embryo, including several cell types present within the mesoderm. The gene is active in the cardiogenic mesoderm, and a loss of function results in an overproduction of both cardial and pericardial cells, indicating a requirement for the gene in the formation of these distinct cardiac cell types. Conversely, ectopic expression of ush results in a decrease in the number of cardioblasts in the heart and the inhibition of a cardial cell enhancer normally regulated by the synergistic activity of the Pannier and Tinman cardiogenic factors. These findings suggest that, similar to its known function in thoracic bristle patterning, Ush functions in the control of heart cell specification through its modulation of Pannier transcriptional activity. ush is also required for mesodermal cell migration early in embryogenesis, where it shows a genetic interaction with the Heartless fibroblast growth factor receptor gene. Taken together, these results demonstrate a critical role for the Ush transcriptional regulator in several diverse processes of mesoderm differentiation and heart formation.
Animals↗
Studies on the cyclosporin A loaded stearic acid nanoparticles.
Stearic acid nanoparticles were prepared in this study by melt-homogenization to investigate the possibility of them as a new kind of drug carrier system. Some physicochemical properties of stearic acid nanoparticles were studied and morphology examined by transmission electron microscope. Cyclosporin A as a model drug was then encapsulated into stearic acid nanoparticles. Following the establishment of high performance liquid chromatography assay for cyclosporin A analysis in stearic acid nanoparticles or blood samples, the encapsulation ratio of cyclosporin A to stearic acid nanoparticles was estimated and pharmacokinetics as well as bioavailability of cyclosporin A stearic acid nanoparticles after oral administration to Wistar rats were studied, using the Sandimmun Neoral(R) (an available microemulsion system of cyclosporin A) as a reference. The mean diameter of cyclosporin A stearic acid nanoparticles was 316.1 nm, while the encapsulation ratio of cyclosporin A to stearic acid nanoparticles reached to 88.36%. It was demonstrated by IR spectra and differential scanning calorimetry that there was no chemical reaction occurred between the cyclosporin A and stearic acid. The relative bioavailability of cyclosporin A stearic acid nanoparticles over reference was nearly 80%, and the time to reach maximum concentration (T(max)) of cyclosporin A after oral administration of cyclosporin A stearic acid nanoparticles was delayed significantly than the reference, suggesting an obvious sustained release effect. The stearic acid nanoparticles might be a very potential drug carrier.
Administration, Oral↗
Rab geranylgeranyl transferase alpha mutation in the gunmetal mouse reduces Rab prenylation and platelet synthesis.
Few molecular events important to platelet biogenesis have been identified. Mice homozygous for the spontaneous, recessive mutation gunmetal (gm) have prolonged bleeding, thrombocytopenia, and reduced platelet alpha- and delta-granule contents. Here we show by positional cloning that gm results from a G-->A substitution mutation in a splice acceptor site within the alpha-subunit of Rab geranylgeranyl transferase (Rabggta), an enzyme that attaches geranylgeranyl groups to Rab proteins. Most Rabggta mRNAs from gm tissues skipped exon 1 and lacked a start codon. Rabggta protein and Rab geranylgeranyl transferase (GGTase) activity were reduced 4-fold in gm platelets. Geranylgeranylation and membrane association of Rab27, a Rab GGTase substrate, were significantly decreased in gm platelets. These findings indicate that geranylgeranylation of Rab GTPases is critical for hemostasis. Rab GGTase inhibition may represent a new treatment for thrombocytosis and clotting disorders.
Alkyl and Aryl Transferases↗
Biosynthesis, post-translation modification, and functional characterization of Drm/Gremlin.
Down-regulated by mos (Drm)/Gremlin is a highly conserved protein whose properties and expression pattern suggest a role in early development, tissue-specific differentiation, and cell transformation. We have investigated the biosynthesis and processing of Drm expressed endogenously in rat fibroblasts or overexpressed following transient or stable transfection. Analysis of metabolically labeled cells revealed that Drm exists in secreted and cell-associated forms that exhibit similar mobilities in SDS-polyacrylamide gel electrophoresis. Protein analysis indicated that Drm is present in two major species: a slow migrating glycosylated form and a nonglycosylated form. Both forms of Drm are able to undergo phosphorylation. Drm is released into the media within 30 min of synthesis and is detectable for up to 4-5 h, whereas the cell-associated form has a half-life of about 1 h. Confocal immunofluorescent microscopy indicates that Drm is present both on the external surface of expressing cells, as well as within the endoplasmic reticulum and the Golgi. Both glycosylated and nonglycosylated forms of Drm exhibit identical distributions and are able to antagonize bone morphogenetic protein signaling. Like the soluble form, the cell-associated forms are capable of binding (125)I-bone morphogenetic protein-4. These properties are consistent with a role for Drm in interfering with signaling and indicate that Drm may act at the cell surface during tissue development and transformation.
Animals↗
The genome sequence of Drosophila melanogaster.
The fly Drosophila melanogaster is one of the most intensively studied organisms in biology and serves as a model system for the investigation of many developmental and cellular processes common to higher eukaryotes, including humans. We have determined the nucleotide sequence of nearly all of the approximately 120-megabase euchromatic portion of the Drosophila genome using a whole-genome shotgun sequencing strategy supported by extensive clone-based sequence and a high-quality bacterial artificial chromosome physical map. Efforts are under way to close the remaining gaps; however, the sequence is of sufficient accuracy and contiguity to be declared substantially complete and to support an initial analysis of genome structure and preliminary gene annotation and interpretation. The genome encodes approximately 13,600 genes, somewhat fewer than the smaller Caenorhabditis elegans genome, but with comparable functional diversity.
Animals↗
A whole-genome assembly of Drosophila.
We report on the quality of a whole-genome assembly of Drosophila melanogaster and the nature of the computer algorithms that accomplished it. Three independent external data sources essentially agree with and support the assembly's sequence and ordering of contigs across the euchromatic portion of the genome. In addition, there are isolated contigs that we believe represent nonrepetitive pockets within the heterochromatin of the centromeres. Comparison with a previously sequenced 2.9- megabase region indicates that sequencing accuracy within nonrepetitive segments is greater than 99. 99% without manual curation. As such, this initial reconstruction of the Drosophila sequence should be of substantial value to the scientific community.
Algorithms↗
Mechanistic and kinetic studies of crystallization of birnessite.
Kinetic and mechanistic features have been studied for the crystallization of birnessite in aqueous systems via different synthesis methods: the oxidation of Mn2+, reduction of MnO4-, and redox reaction between Mn2+ and MnO4-. For oxidation methods, a topotactical conversion from Mn(OH)2 to birnessite via feitknechtite (beta-MnOOH) is observed. In reduction methods, birnessite evolves from the initially produced amorphous manganese oxide (AMO gel). For redox methods, both mechanisms exist, with the latter prevailing. A liquid mechanism is proposed to describe the reduction and redox synthesis, which comprises three stages: an induction period, a fast crystallization period, and a steady-state period. The redox method is accompanied by the formation and phase transformation of feitknechtite to birnessite. A method combining IR and XRD quantitation is proposed to detect nuclei in the induction period. Crystallization rates and apparent energies of activation of crystallization for reduction and redox methods are determined.
Journal Article↗
Molecular cloning, characterization and expression of a novel retinal clusterin-like protein cDNA.
A novel gene expressed predominantly in retina, but detected at a conspicuously lower level in retina of canine progressive rod cone degeneration (prcd), has been identified by suppression subtractive hybridization and retinal cDNA library screening. The characterized region of cDNA of the novel gene includes 1017 nucleotides of coding sequence predicted to encode a protein of 338 amino acids (M(r) 39389), 791 nucleotides of 5'-untranslated region (UTR), and 300 nucleotides of 3'-UTR including the poly(A)(+) tail. Multiple transcripts were detected in retina by Northern blot analysis, and a lower level of expression was observed in brain and liver by RT-PCR. The transcript appears to be developmentally regulated with a burst in gene expression at a time period (34 postnatal days) that coincides with the photoreceptor differentiation phase of retinal development. The deduced amino acid sequence from the cDNA of the novel gene has 24% identity and 48% similarity with the multifunctional glycoprotein clusterin. Hence, the putative gene product from the novel transcript has been named clusterin-like protein 1 (CLUL1). The human homologue of CLUL1 cDNA has 84 and 70% identity at the level of nucleotides and amino acids, respectively, with the characterized canine cDNA. The presence of a stretch of 128 amino acids in the putative human CLUL1, not detected in canine CLUL1, suggests alternate splicing events. An STS database search revealed that the human homologue of CLUL1 maps to chromosome 18p, a location not yet reported to harbor an RP locus. Tissue-specific expression of CLUL1 in retina, and its lower abundance in different forms of PRA suggest that this novel gene may represent an as-yet unidentified locus for a retinal disorder.
Amino Acid Sequence↗
Thymidine phosphorylase expression in tumor stroma of uterine cervical carcinomas: histological features and microvessel density.
Immunohistochemical staining was performed on 91 cases of uterine neoplasm in order to determine if expression of platelet-derived endothelial cell growth factor/thymidine phosphorylase (TP) correlates with tumor microvessel density (MVD) and histological parameters of uterine carcinomas in tumor cells and in tumor stroma. The sample group consisted of 72 primary invasive squamous cell carcinomas of the cervix (ISC) and 19 cervical intraepithelial neoplasms (CIN) of the uterus. In ISC of the cervix, TP expression in tumor stroma showed a significant correlation with a non-keratinizing histological subtype (P < 0.001) and with an infiltrating invasive pattern (P < 0.001). However, in tumor cells the TP expression showed a higher correlation with a keratinizing histological subtypes (P = 0.009). MVD was significantly higher (P = 0.002) in tumors showing high TP expression in stroma than in tumors with low expression. These findings suggest that the TP expression in stromal cells, rather than in tumor cells, may play a role in promoting microvessel growth in cervical squamous cell carcinoma, and angiogenesis may also have an association with tumor cell invasion.
Carcinoma, Squamous Cell↗
Recent, extensive, and preferential insertion of members of the miniature inverted-repeat transposable element family Heartbreaker into genic regions of maize.
A 314-bp DNA element called Heartbreaker-hm1 (Hbr-hm1) was previously identified in the 3' untranslated region of a mutant allele of the maize disease resistance gene HM1. This element has structural features of miniature inverted-repeat transposable elements (MITEs) and is a member of a large family of approximately 4,000 copies in the maize genome. Unlike previously described MITEs, most members of the Hbr family display over 90% sequence identity. This, coupled with the insertion of an Hbr element into an allele of the HM1 gene, suggested that this family might have spread recently throughout the genome. Consistent with this view is the finding that Hbr insertion sites are remarkably polymorphic. Ten of ten loci containing Hbr elements were found to be polymorphic for the presence or absence of Hbr among a collection of maize inbred lines and teosinte strains. Despite the fact that over 80% of the maize genome contain moderate to highly repetitive DNA, we find that randomly chosen Hbr elements are predominantly in single or low copy regions. Furthermore, when used to query both the public and private databases of plant genes, over 50% of the sequences flanking these Hbr elements resulted in significant "hits." Taken together, these data indicate that the presence or absence of Hbr elements is a significant contributory factor to the high level of polymorphism associated with maize genic regions.
Base Sequence↗
Neuronal fractalkine expression in HIV-1 encephalitis: roles for macrophage recruitment and neuroprotection in the central nervous system.
HIV-1 infection of the brain results in chronic inflammation, contributing to the neuropathogenesis of HIV-1 associated neurologic disease. HIV-1-infected mononuclear phagocytes (MP) present in inflammatory infiltrates produce neurotoxins that mediate inflammation, dysfunction, and neuronal apoptosis. Neurologic disease is correlated with the relative number of MP in and around inflammatory infiltrates and not viral burden. It is unclear whether these cells also play a neuroprotective role. We show that the chemokine, fractalkine (FKN), is markedly up-regulated in neurons and neuropil in brain tissue from pediatric patients with HIV-1 encephalitis (HIVE) compared with those without HIVE, or that were HIV-1 seronegative. FKN receptors are expressed on both neurons and microglia in patients with HIVE. These receptors are localized to cytoplasmic structures which are characterized by a vesicular appearance in neurons which may be in cell-to-cell contact with MPs. FKN colocalizes with glutamate in these neurons. Similar findings are observed in brain tissue from an adult patient with HIVE. FKN is able to potently induce the migration of primary human monocytes across an endothelial cell/primary human fetal astrocyte trans-well bilayer, and is neuroprotective to cultured neurons when coadministered with either the HIV-1 neurotoxin platelet activating factor (PAF) or the regulatory HIV-1 gene product Tat. Thus focal inflammation in brain tissue with HIVE may up-regulate neuronal FKN levels, which in turn may be a neuroimmune modulator recruiting peripheral macrophages into the brain, and in a paracrine fashion protecting glutamatergic neurons.
Adult↗
Synthesis of a silica-bonded bovine serum albumin s-triazine chiral stationary phase for high-performance liquid chromatographic resolution of enantiomers.
A novel method of synthesizing protein chiral stationary phase (protein-CSP) is proposed with 2,4,6-trichloro-1,3,5-triazine as the activator. The bovine serum albumin (BSA) based chiral columns (150 x 4.6 mm I.D.) were prepared successfully within 8 h. With tryptophan as the probe solute, it was observed that the BSA immobilized by this method had a better ability to distinguish enantiomers than that activated by glutaric dialdehyde. This may be due to the well-maintained BSA conformation and the larger amount of BSA immobilized on the silica gel. The BSA-CSP prepared by this method was relatively stable under experimental conditions, and the resolution of 13 chiral compounds was achieved. The coupling reaction in this method is mild, reliable and reproducible; it is also suitable for the immobilization of various biopolymers in the preparation of bioreactor, biosensor and affinity chromatography columns.
Chromatography, High Pressure Liquid↗
Changes of free fatty acids and acyl-CoAs in rat brain hippocampal slice with tetraethylammonium-induced long-term potentiation.
We investigated the role of acyl-CoAs during induction and maintenance of long-term potentiation in rat brain hippocampus. Changes of acyl-CoA and free fatty acids (FFA) in hippocampus were measured during tetraethylammonium (TEA)-induced LTP. Results indicated that concentrations of acyl-CoAs and FFAs in slices were changed during TEA-induced LTP and 16:0-CoA and 18:0-CoA were increased in the early phase of stimulation, whereas free fatty acids in this phase were rather decreased. The increase of 20:4-CoA was delayed more than saturated acyl-CoAs. To examine the role of acyl-CoA in LTP of evoked transmitter release, we measured the glutamate release from hippocampal slice with the addition of acyl-CoA using glutamate electrode. Acyl-CoA (16:0-, 18:1-, and 20:4-CoA) could enhance glutamate release in hippocampal slice. It is suggested that saturated acyl-CoAs may play a functional role in the early phase of LTP.
Acyl Coenzyme A↗
Loss of neurons in magnocellular and parvocellular layers of the lateral geniculate nucleus in glaucoma.
OBJECTIVES: To determine whether there is loss of lateral geniculate nucleus relay neurons, which convey visual information to the visual cortex, in experimental glaucoma in monkeys. METHOD: Four cynomolgus monkeys with experimentally induced glaucoma in the right eye (referred to as the glaucoma group) and 5 control monkeys were studied. In both groups, the same conditions of fixation, tissue processing, staining, and measurement were used. In each monkey, the left lateral geniculate nucleus target neurons in magnocellular layer 1 and parvocellular layers 4 and 6, connected to the right glaucomatous eye, were studied. Immunocytochemistry with antibody to parvalbumin was used to specifically label relay neurons connecting to the visual cortex. The number of parvalbumin-immunoreactive neurons was estimated using an unbiased 3-dimensional counting method. The t test was used to compare the experimental and control groups. RESULTS: The mean ( SD) number of neurons in mavnocellular layer 1 was significantly decreased in the glaucoma group compared with the control group (20 692 9567 vs 37 687 8017; P = .02). The mean ( SD) number of neurons in parvocellular layers 4 and 6 was significantly decreased in the glaucoma group compared with the control group (100 141 44 906 vs 174 090 39 136; P = .03). Data are given as the mean SD. CONCLUSION: Significant loss of lateral geniculate nucleus relay neurons terminating in the primary visual cortex occurs in the magnocellular and parvocellular layers in an experimental monkey model of glaucoma. CLINICAL RELEVANCE: Knowledge of the fate of neurons in the central visual system may lead to a better understanding of the nature and progression of visual loss in glaucomatous optic neuropathy.
Animals↗
Regioselective synthesis and electron impact mass spectral fragmentation differentiation of 2- or 3-isopropylthio, phenylthiosuccinic acid 4-methyl/isopropyl ethers.
2- and 3-isopropylthio/phenylthiosuccinic acid 4-methyl/isopropyl esters were synthesized regioselectively by Michael additions of isopropylthiol/thiophenol to maleic anhydride, followed by alcoholysis with methanol/isopropanol. Their mass spectrometric behavior has been studied with the aid of mass-analyzed ion kinetic energy spectrometry and accurate mass measurements under electron impact ionization. All compounds show a tendency to eliminate an alkoxy group, an alcohol, or an alkoxycarbonyl group from the respective molecular ion. Some molecular ions also show a tendency to eliminate a molecule of water, propene or CO(2). The [M - MeCH = CH(2)](+) ions could further lose H(2)O to form substituted succinic anhydride ions, or lose CO(2) to form 3-substituted propionic acid ions. Both of these ions could further yield other small fragment ions by loss of CO(2)H, CO or other small fragments. It has been found that 2-isopropylthio- and 3-phenylthiosuccinic acid 4-esters show more abundant [M - H(2)O](+) peaks than their 3-isopropylthio and 2-phenylthio isomers in their mass spectra.
Carboxypeptidases↗
Electron impact mass spectral fragmentation of 3a,5-disubstituted 1, 3-diphenyl-3a,4,5,6-tetra-hydro-3H-1,2,4-triazolo[4,3-a][1, 5]benzo-diazepines.
The mass spectrometric behaviour of six 3a,5-disubstituted 1, 3-diphenyl-3a,4,5,6-tetrahydro-3H-1,2,4-triazolo[4,3-a][1, 5]benzodiazepines has been studied with the aid of mass-analyzed ion kinetic energy spectrometry and accurate mass measurements under electron impact ionization. All compounds show a tendency to eliminate (substituted) styrene molecules, aryl radicals, arylmethyl radicals or phenylnitrene (PhN:). All of the resulting fragment ions, except [M - PhN:](+.), could further undergo a reverse [2 + 3] cycloaddition. The [M - PhN:](+.) ions could further lose styrene derivatives and undergo a ring enlargement rearrangement. The molecular ions also show a tendency to eliminate a phenyl radical, and the [M - Ph](+) ions could eliminate styrene derivatives. The [M - R(1)CH = CH(2)](+.) ions could further lose NH(2) to yield stable tetracyclic 1,3-diphenyl-1,2,4-triazolo[4,3-d]phenanthridine ions, which could further lose benzonitrile, or undergo a reverse [2 + 3] cycloaddition. The molecular ions could also undergo a reverse [2 + 3] cycloaddition to produce N-phenylbenzonitrile imine ions and 2, 4-disubstituted 2,3-dihydro-1H-1,5-benzodiazepine ions, whose further fragmentations were also investigated.
Anti-Anxiety Agents↗
Alkaline treatment of the cellulose fiber affecting membrane column behaviour for high-performance immunoaffinity chromatography.
The original cellulose fibers and those treated by alkaline solution were both used to prepare the acrylic membranes. The two kinds of membranes were packed into the columns for high-performance immunoaffinity chromatography by the immobilization of protein A on them. It was observed that the alkaline treatment of the cellulose fiber decreased the pressure resistance of the membrane to the mobile phases and greatly increased the accessible volume to the proteins, but affected the adsorption capacity of human IgG on the protein A membrane columns less. There is little difference between those two kinds of membranes on the adsorption capacities of HIgG, which means that the alkaline treatment of the cellulose fiber only significantly changes the void volume inter-membrane, and the porosity and surface area of membrane less. Alkaline treatment of the cellulose fiber reduced the membrane-column efficiency significantly. Some typical examples for the immunoaffinity analysis of IgG from human and dog plasma on the protein A membrane columns are illustrated.
Alkalies↗