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Biomedical subjects

J Yu

Publications and source records attributed to J Yu.

At least 685 records · Page 38Linked to original sources
PubMed1995

[Erythrocyte immunity and regulating factors in mice infected with Plasmodium berghei ANKA strain].

After seventy-two ICR mice were inoculated with Plasmodium berghei ANKA strain, parasitaemia was revealed in all animals inoculated in two to seven days. During the course the number of malaria parasites increased rapidly from 2.3 +/- 1.3 x 10(3) on d2 to 93.7 +/- 1.8 x 10(3) on d7, the number of erythrocytes increased from 8.2 +/- 0.9 x 10(12)/L on d0 to 11.1 +/- 1.0 x 10(12)/L on d2 and then decreased gradually, reaching 1.9 +/- 0.4 x 10(12)/L on d7, and the number of white blood cells appeared to be fluctuated. Additionally, the rosette rate of erythrocyte=C3b receptor and the rosette rate of erythrocyte-immunocomplex increased on d2 and then decreased gradually to a very low level, suggesting that the erythrocyte immune function reduced in malaria. It is assumed that the reduction in erythrocyte immune function in malaria is attributed to the damage of the erythrocyte membrane in addition to the changes in the function of the erythrocyte immunoregulating factors.

Animals↗
PubMed1995

[Detection of CgA mRNA in neuroendocrine cells in gastric carcinoma by in situ hybridization].

Fresh gastric carcinoma specimens from 17 cases were collected. The neuroendocrine (NE) cells in gastric carcinoma (GC) and gastric mucosa adjacent to the carcinoma (GMAC) were observed using in situ hybridization of chromogranin A (CgA) oligonucleotide probe and compared with immunohistochemistry of CgA antibody. 5 of the 17 cases of GC showed CgA mRNA positive expression and 7 of the 17 cases expressed CgA protein positively. The simultaneous expression of mRNA and protein of CgA was present in 4 cases. The NE cells in GC not only can store and secrete CgA protein products but also possess the ability to synthesize NE products from gene expression.

APUD Cells↗
PubMed1994

Clinical significance of p53 mutations in relapsed T-cell acute lymphoblastic leukemia.

In T-cell acute lymphoblastic leukemia (T-ALL), p53 gene mutations were found in 12 of 51 patients in first relapse (24%). In a retrospective study, bone marrow samples at diagnosis were obtained from 9 of the 12 relapsed patients with p53 mutation; only one patient was found to harbor a p53 mutation at diagnosis. No further p53 mutations were identified in 18 unpaired diagnosis T-ALL samples. This is the first report of a p53 mutation in T-ALL at diagnosis. p53 mutations in relapsed T-ALL were clinically relevant. Patients with p53 mutations experience a shorter duration of survival than those patients without p53 mutations. Additionally, patients with p53 mutations were significantly less likely to have achieved a complete second remission from reinduction therapy than those patients without p53 mutations and experience a shorter duration of survival from relapse even when a second reinduction is obtained. Though primarily identified only at relapse, p53 mutations were also associated with a decreased duration of first remission and overall decrease in survival from diagnosis. Patients with p53 mutations had a 3.8-fold increase in risk of death than those patients without p53 mutations. These findings suggest that p53 mutation is associated with poor clinical outcome that is characterized by (1) a shortened duration of survival after first relapse; (2) a reduced response to reinduction therapy; (3) a shortened duration of first remission; and, hence, (4) an overall decreased duration of survival and increased risk of death.

Base Sequence↗
PubMed1994

Ankyrin and beta-spectrin accumulate independently of alpha-spectrin in Drosophila.

We report the identification and initial characterization of Drosophila melanogaster ankyrin. Oligonucleotide primers based on the spectrin-binding domain of human brain ankyrin were used to amplify Drosophila genomic DNA. A cloned 184-bp PCR product was used to isolate Drosophila ankyrin cDNAs. Ankyrin cDNA probes detected a 5.5-kb transcript from embryonic poly(A)+ RNA and a single polytene chromosome locus (101F-102A). The cDNA sequence encodes a 170-kDa protein that is 53% identical to human brain ankyrin (Ank2). Antibodies directed against a recombinant fragment of Drosophila ankyrin reacted with a 170-kDa polypeptide from Drosophila embryos, larvae, S2 cells, and adult flies. The ankyrin antibody coimmunoprecipitated alpha- and beta-spectrin with ankyrin in detergent extracts of Drosophila embryo membranes. Antibodies against Drosophila ankyrin, alpha-spectrin and beta-spectrin were used to detect these proteins in wild-type and alpha-spectrin-mutant larvae. alpha-Spectrin levels were greatly diminished in mutant larvae, but levels of ankyrin and beta-spectrin were indistinguishable from wild type. The persistence of ankyrin and beta-spectrin may explain the relatively mild phenotype of alpha-spectrin mutants during early Drosophila development.

Amino Acid Sequence↗
PubMed1994

Solid-phase derivatization reactions for biomedical liquid chromatography.

Polymeric reagents have been developed for performing off- and on-line derivatizations of numerous organic analytes in HPLC-detection modes. Such reagents utilize ionic or covalent attachment of labile tags that possess specific detector enhancement properties: ultraviolet, electrochemical, fluorescence, and so forth. Specific synthetic procedures have evolved to generate various linkages of the tag to the underlying, polymeric support, usually involving activated ester connections (leashes). The polymer itself may play a number of roles in the nature of the overall reactions, such as hydrophobic-hydrophillic exclusion, pore size restriction, stabilization of the attachment leashes, and protection of the tags from hydrolysis in aqueous media. The basic, underlying chemistry of polymeric reagents has evolved to the point where it is possible to engineer the polymer support itself, the attachment leash, and the various tags that are then transferred to the analyte molecules. These procedures have now reached the stage of commercialization and practical applicability for real-world drugs and bioorganics in complex biofluid type samples. Polymer supported reagents can now be used for direct injection of biofluids with solid-phase (hydrophobic) extraction of the analytes of interest, followed by sample cleanup, derivatization, elution onto the HPLC column, peak compression, gradient HPLC elution, multiple detection, and final data interpretation with quantitation. This review summarizes much or most of what has been described in the scientific literature over the past decade in the various areas where polymeric reagents are being used for derivatization in HPLC and in capillary electrophoresis as well.

Chemistry Techniques, Analytical↗
PubMed1994

Mammalian uroplakins. A group of highly conserved urothelial differentiation-related membrane proteins.

The asymmetric unit membrane (AUM) forms the apical plaques of mammalian urothelium and is believed to play a role in strengthening the urothelial apical surface thus preventing the cells from rupturing during bladder distention. We have shown previously that purified bovine AUMs contain four major integral membrane proteins: the uroplakins Ia (27 kDa), Ib (28 kDa), II (15 kDa), and III (47 kDa). This contradicts some previous reports indicating that some of these proteins are absent in AUMs of several species. Using an improved procedure, we isolated AUMs from, in addition to cattle, eight mammalian species (human, monkey, sheep, pig, dog, rabbit, rat, and mouse). The AUMs of these species appear morphologically similar bearing crystalline patches of 12-nm protein particles with a center-to-center spacing of 16.5 nm. Using antibodies raised against synthetic oligopeptides or individual bovine uroplakins, we established by immunoblotting that the four uroplakins are present in AUMs of all these species. The DNA-deduced amino acid sequences of bovine and mouse uroplakin II revealed 83% identity. These results indicate that uroplakins Ia, Ib, II, and III are the major protein components of probably all mammalian urothelial plaques, and that the sequence and three-dimensional structure of uroplakin molecules are highly conserved during mammalian evolution.

Amino Acid Sequence↗
PubMed1994

Detection of functional and dimeric activin A in human marrow microenvironment. Implications for the modulation of erythropoiesis.

Activin A, which was initially recognized as a gonadal protein, was implicated in the modulation of erythropoiesis through a paracrine control in the bone marrow microenvironment. Present studies demonstrate that, in contrast to T lymphocytes and cultured skin fibroblasts, human marrow stromal cells produce a functional and dimeric beta A beta A molecule (i.e., activin A). RT-PCR further indicates that both alpha and beta A mRNAs of inhibin A/activin A are produced in human stromal cells. The level of beta A subunit mRNAs, however, is in large excess over that of alpha subunit mRNAs, suggesting the predominant production of beta A beta A dimers, as well as some inhibin A (alpha beta A). It should be noted, however, that the beta A subunit can form dimeric proteins other than activin A, such as activin AB (beta A beta B) and inhibin A (alpha beta A). Hence, the presence of the beta A subunit may not necessarily indicate the production of the activin A molecule in any tissue. Therefore, a special quantitative sandwich ELISA assay specific for the dimeric beta A beta A molecule was developed for the measurement of activin A. With this assay, production of activin A in marrow stromal cells is found to be greatly enhanced by cytokines and inflammatory mediators such as TNF-alpha, IL-1 alpha, and lipopolysaccharide. These studies thus suggest that inflammatory cytokines are the inducers for activin A, probably serving a role of up-regulating activin A production locally in bone marrow microenvironment. At present, activin A is not known to play any role in inflammatory reaction; this study may thus raise the possibility that activin A performs more functions than are currently recognized. Alternatively, the enhanced production of this molecule in the bone marrow microenvironment may be regarded as a compensatory mechanism in host defenses, countering inflammatory mediators that are known to suppress erythropoiesis.

Activins↗
PubMed1994

A 5' beta-globin matrix-attachment region and the polyoma enhancer together confer position-independent transcription.

Insertions of reporter constructs into the genome of higher eukaryotes typically lead to variegated gene expression due to position effects at the sites of integration. The 20-kb human beta-globin (beta Glb) locus control region (LCR) has been found to dampen these position effects when included in an expression vector. Several studies have indicated that much of the activity of the beta Glb-LCR resides in hypersensitive site II, which contains a strong enhancer. In this study, we have focused on the matrix-attachment region (MAR) at the 5' boundary of the beta Glb-LCR. We find that the beta Glb-MAR, by itself, has little effect on transcription of a reporter gene in stable transformants. However, when the beta Glb-MAR is linked in cis with the polyoma virus enhancer, the MAR-enhancer construct confers high levels of copy-dependent transcription that is independent of the chromosomal site of integration. These results suggest that the beta Glb-MAR may work synergistically with particular enhancer elements to dampen chromosomal position effects and ensure high-level expression.

Base Sequence↗
PubMed1994

Dielectric properties of human red blood cells in suspension at radio frequencies.

Dielectric properties of human red blood cells (RBCs) in suspension (hematocrit 50%) from 243 healthy persons (120 males, 123 females) were measured at 25 degrees C in a frequency range of 1-500 MHz, with a coaxial transmission line reflection method (one-side measurement). The measuring system, controlled by an IBM-PC computer, was composed of a network analyzer (HP4195A), an impedance test adapter (HP41951-61001), a coaxial line sensor, and a temperature-controlling set. The data measured revealed a statistically significant age dependence, with a critical age of about 49 years, above which permittivity and conductivity of human RBCs in suspension decreased significantly.

Adult↗
PubMed1994

Potential role of bile duct collaterals in the recovery of the biliary obstruction: experimental study in rats using microcholangiography, histology, serology and magnetic resonance imaging.

Obstructive cholestasis induced in animals at the level of the lobar and common bile ducts is known to be reversible with time. This study was conducted not only to test the hypothesis that formation of bile duct collaterals is responsible for the recovery of biliary obstruction but also to assess the potential of hepatobiliary agent-enhanced magnetic resonance imaging for visualizing cholestasis. A total of 52 rats were divided into three groups with selective biliary obstruction, total biliary obstruction and sham surgery. We studied the evolution of cholestasis by correlating microcholangiographic, histological findings with the results of liver tests and hepatobiliary agent-enhanced magnetic resonance imaging. Lobar cholestasis undetected by liver tests but seen on magnetic resonance imaging as a difference between ligated and unligated lobes, occurred in 15 out of 20 rats subjected to selective biliary obstruction within 48 hr after ligation, and recovered later on as a result of the development of bile duct collaterals. Five rats failed to show local cholestasis as a result of the existence of interlobar accessory bile channels. All 18 total biliary obstruction-treated rats were cholestatic soon after ligation, as confirmed by high serum bilirubin and alkaline phosphatase levels and as documented by poor liver enhancement on magnetic resonance imaging. Cholestasis recovered within 4 wk with normalization of liver enhancement on magnetic resonance imaging as a result of the formation of bile duct collaterals (as demonstrated by microcholangiographic and histological study). Bile duct collateral formation is responsible for the recovery from obstructive cholestasis in rats. A similar mechanism might be present in conditions of bile duct obstruction without cholestasis. Hepatobiliary agent-enhanced magnetic resonance imaging is more sensitive than blood tests in detecting local cholestasis and can be used to monitor noninvasively the evolution of biliary obstruction.

Alanine Transaminase↗
PubMed1994

Isolation and refined regional mapping of expressed sequences from human chromosome 21.

To increase candidate genes from human chromosome 21 for the analysis of Down syndrome and other genetic diseases localized on this chromosome, we have isolated and studied 9 cDNA clones encoded by chromosome 21. For isolating cDNAs, single-copy microclones from a chromosome 21 microdissection library were used in direct screening of various cDNA libraries. Seven of the cDNA clones have been regionally mapped on chromosome 21 using a comprehensive hybrid mapping panel comprising 24 cell hybrids that divide the chromosome into 33 subregions. These cDNA clones with refined mapping positions should be useful for identification and cloning of genes responsible for the specific component phenotypes of Down syndrome and other diseases on chromosome 21, including progressive myoclonus epilepsy in 21q22.3.

Adult↗
PubMed1994

Modification of lignin biosynthesis in transgenic Nicotiana through expression of an antisense O-methyltransferase gene from Populus.

An aspen lignin-specific O-methyltransferase (bi-OMT; S-adenosyl-L-methionine: caffeic acid/5-hydroxyferulic acid 3/5-O-methyltransferase, EC 2.1.1.68) antisense sequence in the form of a synthetic gene containing the cauliflower mosaic virus 35S gene sequences for enhancer elements, promoter and terminator was stably integrated into the tobacco genome and inherited in transgenic plants with a normal phenotype. Leaves and stems of the transgenes expressed the antisense RNA and the endogenous tobacco bi-OMT mRNA was suppressed in the stems. Bi-OMT activity of stems was decreased by an average of 29% in the four transgenic plants analyzed. Chemical analysis of woody tissue of stems for lignin building units indicated a reduced content of syringyl units in most of the transgenic plants, which corresponds well with the reduced activity of bi-OMT. Transgenic plants with a suppressed level of syringyl units and a level of guaiacyl units similar to control plants were presumed to have lignins of distinctly different structure than control plants. We concluded that regulation of the level of bi-OMT expression by an antisense mechanism could be a useful tool for genetically engineering plants with modified lignin without altering normal growth and development.

Base Sequence↗
PubMed1994

A region-specific microdissection library for human chromosome 2p23-p25 and the analysis of an interstitial deletion of 2p23.3-p25.1.

A region-specific library for human chromosome 2p23-p25 was constructed using microdissection and polymerase chain reaction (PCR)-mediated microcloning techniques. This library is large, comprising 300,000 recombinant microclones. The insert sizes range between 50-600 base pairs (bp) with a mean of 200 bp. About 50%-60% of the clones contain unique or very low copy number sequence inserts as determined by their weak or no hybridization to total human DNA. A subset of 48 microclones that did not hybridize to total human DNA after colony hybridization was analyzed, and 26 (54%) clones were shown to contain single-copy inserts and hybridize to human chromosome 2 DNAs, indicating that they are human chromosome 2 specific. The human genomic fragments identified by these clones after cleavage with HindIII have also been characterized. The single-copy microclones were used to analyze an interstitial deletion in the 2p23.3-p25.1 region--46,XY, del(2) (pter-->p25.1::p23.3-->qter)--previously reported in a patient with severe growth and mental retardation and multiple anomalies. Of the 26 microclones analyzed, 14 clones were mapped to the deletion region. The availability of the 2p23-p25 region-specific library and the probes derived from the library should be valuable for fine structure physical mapping analysis and the cloning of disease-related genes localized to the region. These studies also demonstrate the efficiency with which useful probes can be quickly generated for genome studies and for positional cloning.

Animals↗
PubMed1994

Effects of peptone on hybridoma growth and monoclonal antibody formation.

Hybridoma WuT3 secreting a monoclonal antibody against T lymphocytes was grown in RPMI 1640 medium supplemented with 1% human serum. The effect of the concentration of peptone, as an additive, was investigated on cell growth, monoclonal antibody formation, and cell metabolism over 0-10 g l-1 range. It was found that 1-5 g l-1 peptone can significantly promote the growth of cells and increase the formation of monoclonal antibody, especially at 3-5 g l-1, when both the accumulating level and secretion rate of monoclonal antibody are higher than that at other peptone concentrations. Based on glucose, lactate and ammonia analysis data, the efficiency of glycolysis was assessed and the utilization of amino acids was more efficient at 3-5 g l-1 peptone. The cell growth and monoclonal antibody formation were inhibited at higher peptone concentrations, e.g. 10 g l-1.

Amino Acids↗