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J Lee

Publications and source records attributed to J Lee.

At least 451 records · Page 25Linked to original sources
PubMed2000

Prostasomes: current concepts.

BACKGROUND: Prostasomes are membranous vesicles secreted by prostate gland, and they contain large amounts of cholesterol, sphingomyelin, calcium, and several enzymes. Prostasomes are involved in a number of biological functions. At ejaculation, these prostasomes are expelled with prostate secretions and are to be found in the seminal plasma as seminal prostasomes, which facilitate sperm function in various ways. METHODS: In this review, we discuss the structural and functional role of prostasomes, the various enzyme systems associated with these vesicles, and the biological role prostasomes play in male reproduction. RESULTS AND CONCLUSIONS Prostasomes are pluripotent and well-organized organelles secreted by the prostate gland. Prostasomes are ascribed to have many physiologiocal functions, the primary function being enhancement of sperm capacity. The several enzyme systems, small signaling molecules, and neuroendocrine markers associated with prostasomes reveal the complex nature of these vesicles in regulating sperm viability and vitality. The functional significance of these molecules that regulate complex pathways in these small vesicles is still a matter of dogma. Critical evaluation of the biological processes associated with prostasomes might be helpful in modeling new contraceptive agents, improving the techniques of in vitro fertilization, and in furthering our understanding and treatment of male factor infertility.

Acrosome↗
PubMed2000

Synthesis and structure-activity relationship of novel pyridyl ethers for the nicotinic acetylcholine receptor.

The preparation of novel pyridyl ethers as ligands for the nicotinic acetylcholine receptor (nAChR) is described. Variations of the ring size of the azacycle and substitution on the pyridine had dramatic effects on receptor binding affinity with IC50s at the alpha4beta2 nAChR ranging from 22 to >10,000 nM. The most potent molecule was (R)-2-chloro-3-(4-cyanophenyl)-5-((3-pyrrolidinyl)oxy)pyridine 27f with an IC50 of 22 nM.

Bridged Bicyclo Compounds, Heterocyclic↗
PubMed2000

Drosophila beta spectrin functions independently of alpha spectrin to polarize the Na,K ATPase in epithelial cells.

Spectrin has been proposed to function as a sorting machine that concentrates interacting proteins such as the Na,K ATPase within specialized plasma membrane domains of polarized cells. However, little direct evidence to support this model has been obtained. Here we used a genetic approach to directly test the requirement for the beta subunit of the alphabeta spectrin molecule in morphogenesis and function of epithelial cells in Drosophila. beta Spectrin mutations were lethal during late embryonic/early larval development and they produced subtle defects in midgut morphology and stomach acid secretion. The polarized distributions of alphabeta(H) spectrin and ankyrin were not significantly altered in beta spectrin mutants, indicating that the two isoforms of Drosophila spectrin assemble independently of one another, and that ankyrin is upstream of alphabeta spectrin in the spectrin assembly pathway. In contrast, beta spectrin mutations had a striking effect on the basolateral accumulation of the Na,K ATPase. The results establish a role for beta spectrin in determining the subcellular distribution of the Na, K ATPase and, unexpectedly, this role is independent of alpha spectrin.

Animals↗
PubMed2000

Functional characterization of Caenorhabditis elegans DNA topoisomerase IIIalpha.

To investigate the function of a DNA topoisomerase III enzyme in Caenorhabditis elegans, the full-length cDNA of C.elegans DNA topoisomerase IIIalpha was cloned. The deduced amino acid sequence exhibited identities of 48 and 39% with those of human DNA topoisomerase IIIalpha and Saccharomyces cerevisiae DNA topoisomerase III, respectively. The overexpressed polypeptide showed an optimal activity for removing negative DNA supercoils at a relatively high temperature of 52-57 degrees C, which is similar to the optimum temperatures of other eukaryotic DNA topoisomerase III enzymes. When topoisomerase IIIalpha expression was interfered with by a cognate double-stranded RNA injection, pleiotropic phenotypes with abnormalities in germ cell proliferation, oogenesis and embryo-genesis appeared. These phenotypes were well correlated with mRNA expression localized in the meiotic cells of gonad and early embryonic cells.

Animals↗
PubMed2000

Entanglement teleportation via werner states

Transfer of entanglement and information is studied for quantum teleportation of an unknown entangled state through noisy quantum channels. We find that the quantum entanglement of the unknown state can be lost during the teleportation even when the channel is quantum correlated. We introduce a fundamental parameter of correlation information which dissipates linearly during the teleportation through the noisy channel. Analyzing the transfer of correlation information, we show that the purity of the initial state is important in determining the entanglement of the replica state.

Journal Article↗
PubMed2000

Characterization of superantigen-induced clonal deletion with a novel clan III-restricted avian monoclonal antibody: exploiting evolutionary distance to create antibodies specific for a conserved VH region surface.

Evolution of the Ab system has yielded three clans of VH region genes that are represented in almost every known higher species with an adaptive immune system. These clans are defined by sequence homologies primarily in highly conserved framework (FR) subdomains, which serve a scaffolding function maintaining the conformation of loops responsible for Ag binding. Structural analyses indicate that the VH FR1 and FR3 form a conserved composite exposed surface, which has been implicated in interactions with B cell superantigens. To directly investigate the expression of clan-defined supraclonal sets, we exploited the evolutionary distance of the chicken immune system and the selection power of phage display, to derive Abs diagnostic for clan III Ig. Using a specially tailored immunization and selection strategy, we created recombinant avian single chain Fv Abs specific for the clan III products, including those from the human VH3 family, and the analogous murine 7183, S107, J606, X24, and DNA4 families, and binding was competitive with natural B cell superantigens. The archetype, LJ-26, was demonstrated to recognize a clan-specific surface expressed in diverse mammalian, and also the Xenopus and chicken, immune systems. In flow-cytometric studies with LJ-26, we found that treatment of heterozygous T15i transgenic mice with a model B cell superantigen induced a clan III-restricted clonal deletion. These studies demonstrate the utility of a novel recombinant serologic reagent to study the composition of the B cell compartment and also the consequences of B cell superantigen exposure.

Amino Acid Sequence↗
PubMed2000

Analysis of the fit-1 gene encoding a ECM protein, flectin, in Caenorhabditis elegans.

Flectin is a new type of extracellular matrix protein and its function was suggested to provide a microenvironment of great elasticity. The C. elegans genome database revealed the presence of a flectin homologue, fit-1, which shows approximately 40% similarity (20% identity) to chick flectin. Here we propose a new gene structure for the fit-1 based on our experiments and the partial cDNA clones obtained from Y. Kohara and further suggest that the previous gene prediction is incorrect. FLT-1 is shown to be expressed in various neurons, hypodermal cells, distal tip cells and vulva epithelial cells. Immunostaining results with anti-FLT-1 antibody, further confirm the FLT-1 expression in vulva epithelial cells. The lipophilic dye, DiI, was used to identify the head neurons expressing GFP and results indicated that none of the head neurons expressing GFP are the 6 chemosensory neurons. In order to determine the function of flt-1 gene, RNA-mediated interference (RNAi) experiments were conducted.

Animals↗
PubMed2000

Mit1/Lb9 and Copg2, new members of mouse imprinted genes closely linked to Peg1/Mest(1).

Two mouse genes, Mit1/Lb9 and Copg2, linked to Peg1/Mest on mouse chromosome 6, were identified to be imprinted maternally and paternally, respectively. Mit1/Lb9 encoding untranslated transcripts resides within the intron 20 of Copg2. The gene is maternally imprinted in adult mouse brain, partially imprinted in other tissues. Copg240 kb genomic region, being expressed ubiquitously in mouse tissues with a partial imprinting pattern in embryos, neonates, and adult brain in contrast to maternally imprinted human COPG2. In addition, we identified an antisense transcript of Copg2, Copg2AS, which overlaps 3'-UTRs of Copg2 and Peg1/Mest. The Copg2AS transcript is maternally imprinted in embryos, neonates, and adult tissues.

Amino Acid Sequence↗
PubMed2000

The functional role of basic patch, a structural element of Escherichia coli transcript cleavage factors GreA and GreB.

The transcript cleavage factors GreA and GreB of Escherichia coli are involved in the regulation of transcription elongation. The surface charge distribution analysis of their three-dimensional structures revealed that the N-terminal domains of GreA and GreB contain a small and large basic "patch," respectively. To elucidate the functional role of basic patch, mutant Gre proteins were engineered in which the size and charge distribution of basic patch were modified and characterized biochemically. We found that Gre mutants lacking basic patch or carrying basic patch of decreased size bind to RNA polymerase and induce transcript cleavage reaction in minimally backtracked ternary elongation complex (TEC) with the same efficiency as the wild type factors. However, they exhibit substantially lower readthrough and cleavage activities toward extensively backtracked and arrested TECs and display decreased efficiency of photocross-linking to the RNA 3'-terminus. Unlike wild type factors, basic patch-less Gre mutants are unable to complement the thermosensitive phenotype of GreA(-):GreB(-) E. coli strain. The large basic patch is required but not sufficient for the induction of GreB-type cleavage reaction and for the cleavage of arrested TECs. Our results demonstrate that the basic patch residues are not directly involved in the induction of transcript cleavage reaction and suggest that the primary role of basic patch is to anchor the nascent RNA in TEC. These interactions are essential for the readthrough and antiarrest activities of Gre factors and, apparently, for their in vivo functions.

Amino Acid Sequence↗
PubMed2000

Characterization of JDP genes, an evolutionarily conserved J domain-only protein family, from human and moths.

We characterized evolutionarily conserved J domain containing protein (JDP) genes from human, Bombyx mori, and Manduca sexta. Each of the JDP proteins contains a J domain at its N-terminus and a highly conserved C-terminal domain. Southern blot analysis revealed that the human JDP1 gene is present as a single copy in the human genome. Expression was higher in brain, heart, and testis than in kidney or stomach. Human JDP1 was mapped in silico to chromosome 10q21.1, which exhibits a conserved synteny with the central region of mouse chromosome 10. Drosophila jdp is located at 99F4-99F11 on the right arm of the third chromosome.

Amino Acid Sequence↗
PubMed2000

Novel therapeutic nano-particles (lipocores): trapping poorly water soluble compounds.

The development of stable spherical lipid-coated drug particles that are termed 'lipocores' is reported here. Unlike conventional lipid-based particles (i.e. liposomes, emulsions, micelles), these particles are comprised solely of a core of a poorly water soluble drug surrounded by polyethyleneglycol conjugated lipid (PEG-lipid) and are formed via a 'kinetic' trapping process. These lipocore particles were made with the acyl chain of 16 carbon length (C16) acyl-chain derivatives of paclitaxel or vinblastine and with the polyene antifungal hamycin. Formation of the particles occurred regardless of the type of PEG-phospholipid used (i.e. acyl chain length, chain saturation, and polymer length) and could also be formed with the negatively charged lipid N-glutaryl-dioleoyl-phosphatidylethanolamine (DOPE-GA). Images from both freeze-fracture electron microscopy and electron cryo-microscopy revealed solid spherical structures with no internal lamellae for the PEG-lipid particles made with the C16 derivatives of paclitaxel (BrC16-T) or vinblastine (C16-Vin). From a solute distribution study of lipocores made with BrC16-T and distearoyl-phosphatidylethanolamine-PEG2000 (DSPE-PEG2000), the particles were found to have no measurable aqueous captured volume. Fluorescence anisotropy and order parameter measurements revealed the core material of these particles to be highly immobilized. The mole ratio of BrC16-T:lipid in the lipocores was typically > 90: < 10 and as high as 98:2, and the refrigerated lipocores were stable for several months. BrC16-T/DSPE-PEG2000 lipocores of 50-100 nm particle size were far less toxic than paclitaxel (Taxol) after intraperitoneally (i.p.) or intravenously (i.v.) administration in mice and were active against i.p. and subcutaneously (s.c.) planted human (OvCar3) ovarian carcinoma grown in SCID mice. It is believed the high drug:lipid ratio, the stability, and therapeutic efficacy of these novel particles make them a paradigm for delivery of poorly water soluble drugs and/or their hydrophobic derivatives.

Animals↗
PubMed2000

Development and characterization of an oxygen-dependent inducible promoter system, the modified nar promoter in a mutant Escherichia coli.

A nar promoter system (a modified nar promoter in a mutant host Escherichia coli (pMW618/W3110narL(-))), which is maximally induced under microaerobic conditions, was developed and characterized through batch and fed-batch culture to see whether the modified nar promoter can be used as an oxygen-dependent inducible promoter in the absence of nitrate ion. The modified nar promoter (pMW618) derived by mutations at -10 and -35 regions of the wild-type nar promoter does not require nitrate ion for the full induction, while a mutant host E. coli, W3110narL(-), does not express nitrate-dependent regulatory protein, NARL, from the host chromosome. In this study, it was found from fed-batch culture that the specific beta-galactosidase activity expressed from the lacZ gene fused to the modified nar promoter in the absence of nitrate ion was maximal when E. coli was grown under aerobic conditions (dissolved oxygen (DO) at 80%) to absorbance at 600 nm (OD(600)) of 35, and then the modified nar promoter was induced by lowering DO to 1-2% with alternating microaerobic and aerobic conditions. The maximal specific beta-galactosidase activity became 58,000 Miller at OD(600) of 160 with an induction ratio of 20. On the basis of these results, we conclude that the modified nar promoter system (pMW618/W3110narL(-)), requiring only reduction of DO for the full induction, provides a convenient and effective high-level expression system under conditions of fed-batch culture.

Bacteriological Techniques↗
PubMed2000

Vascular endothelial growth factor synergistically enhances bone morphogenetic protein-4-dependent lymphohematopoietic cell generation from embryonic stem cells in vitro.

The totipotent mouse embryonic stem (ES) cell is known to differentiate into cells expressing the beta-globin gene when stimulated with bone morphogenetic protein (BMP)-4. Here, we demonstrate that BMP-4 is essential for generating both erythro-myeloid colony-forming cells (CFCs) and lymphoid (B and NK) progenitor cells from ES cells and that vascular endothelial growth factor (VEGF) synergizes with BMP-4. The CD45(+) myelomonocytic progenitors and Ter119(+) erythroid cells began to be detected with 0.5 ng/mL BMP-4, and their levels plateaued at approximately 2 ng/mL. VEGF alone weakly elevated the CD34(+) cell population though no lymphohematopoietic progenitors were induced. However, when combined with BMP-4, 2 to 20 ng/mL VEGF synergistically augmented the BMP-4-dependent generation of erythro-myeloid CFCs and lymphoid progenitors from ES cells, which were enriched in CD34(+) CD31(lo) and CD34(+) CD45(-)cell populations, respectively, in a dose-dependent manner. Furthermore, during the 7 days of in vitro differentiation, BMP-4 was required within the first 4 days, whereas VEGF was functional after the action of BMP-4 (in the last 3 days). Thus, VEGF is a synergistic enhancer for the BMP-4-dependent differentiation processes, and it seems to be achieved by the ordered action of the 2 factors.

Antigens, CD34↗
PubMed2000

Enantiomeric separation and discrimination of 2-hydroxy acids as O-trifluoroacetylated (S)-(+)-3-methyl-2-butyl esters by achiral dual-capillary column gas chromatography.

An efficient method is described for the simultaneous enantiomeric separation of 18 different racemic 2-hydroxy acids for the determination of their absolute configurations. It involves the conversion of each enantiomer into a diastereomeric O-trifluoroacetylated (S)-(+)-3-methyl-2-butyl ester for the direct separation by achiral dual-capillary column gas chromatography with subsequent identification and determination of its chirality by retention index (I) library matching. The enantiomers of each acid were well separated with high resolution values (R > or = 1.4) on DB-5 and DB-17 columns of different polarity. When temperature-programmed I values of 2-hydroxy acid enantiomers as their diastereomeric derivatives were measured on both columns, the I values were characteristic of each enantiomer. Simple I matching with the reference values was thus useful in cross-checking each acid enantiomer for the identification and chiral discrimination. When applied to urine samples, the present method allowed positive identification of most of the spiked 2-hydroxy acids from normal urine and for endogenous (S)-lactic acid and (S)-2-hydroxybutyric acid from a clinical urine specimen.

Chromatography, Gas↗
PubMed2000

Rheumatoid arthritis associated autoantibodies in patients with synovitis of recent onset.

STATEMENT OF FINDINGS: An inception cohort of 238 patients having peripheral joint synovitis of less than 12 months duration was evaluated clinically and followed prospectively for 1 year to determine the clinical significance of a number of rheumatoid arthritis (RA) associated autoantibodies. Serum samples collected at the time of the initial evaluation were tested for rheumatoid factor (RF) and antibodies to Sa (anti-Sa), RA-33, (pro)filaggrin [antifilaggrin antibody (AFA)], cyclic citrullinated peptide (anti-CCP), calpastatin, and keratin [antikeratin antibody (AKA)]. RF had a sensitivity of 66% and a specificity of 87% for RA. Anti-Sa, AFA, and anti-CCP all had a specificity of more than 90%, but a sensitivity of less than 50% for this diagnosis. Overall, there was a high degree of correlation between AFA, AKA, anti-Sa or anti-CCP, this being highest between anti-Sa and anti-CCP (odds ratio, 13.3; P < 0.001). Of the 101 patients who were positive for at least one of these four autoantibodies, 57% were positive for only one. Finally, anti-SA identified a subset of predominantly male RA patients with severe, erosive disease. Anti-SA, AFA and anti-CCP are all specific for early RA but, overall, have little additional diagnostic value over RF alone. Although these antibodies may preferentially recognize citrullinated antigens, the modest degree of concordance between them in individual patient sera suggests that it is unlikely a single antigen is involved in generating these responses.

Acute Disease↗
PubMed2000

Expression of p16(INK4A) induces dominant suppression of glioblastoma growth in situ through necrosis and cell cycle arrest.

Tumor suppressor genes may represent an important new therapeutic modality in the treatment of human glioblastoma (GBM). p16(INK4A) is a tumor suppressor gene with mutation and/or deletion found in many human tumors, including glioblastomas, melanoma, and leukemias. RT-2 rat GBM cell line was used to investigate if the p16 gene induces dominant suppression of glioblastoma growth. Close to 100% of tumor cells were infected by high titer pCL retrovirus encoding the full-length human p16 cDNA at 5 m.o.i. Infected cells showed a 98% reduction in colony forming assay and a 60% reduction in growth curves in vitro compared to vector control. Exogenous overexpression of p16 induced hypophosphorylation of Rb protein by Western blot analysis. Intracranial injection of p16-infected tumor cells into syngeneic rats resulted in a 95% reduction in tumor volume compared to the controls. Intratumoral injection of p16 retrovirus resulted in tumor necrosis and prominent human p16 transgene expressions. Proliferation marker PCNA was not detected in these human p16-expressed RT-2 tumor cells, suggesting the cells were unable to enter into S phase after p16 expression. In addition, direct repeat intracranial injections of p16 retrovirus prolonged animal survival 3.2-fold compared to the controls (48.4 +/- 13.4 vs 15.0 +/- 2.1 days, p < 0.001). Two out of ten rats were found with dormant tumors at day 60 after p16 retrovirus injection. These results showed that p16 is effective in inhibiting GBM growth in situ. The mechanisms of tumor growth reduction and necrosis in vivo might be due to G1 arrest triggered by p16 expression.

Animals↗
PubMed2000

Cosmic Shear from Galaxy Spins.

We discuss the origin of galactic angular momentum and the statistics of the present-day spin distribution. It is expected that the galaxy spin axes are correlated with the intermediate principal axis of the gravitational shear tensor. This allows one to reconstruct the shear field and thereby the full gravitational potential from the observed galaxy spin fields. We use the direction of the angular momentum vector without any information of its magnitude, which requires a measurement of the position angle and inclination on the sky of each disk galaxy. We present the maximum likelihood shear inversion procedure, which involves a constrained linear minimization. The theory is tested against numerical simulations. We find the correlation strength of nonlinear structures with the initial shear field and show that accurate large-scale density reconstructions are possible at the expected noise level.

Journal Article↗