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Biomedical subjects

H Wu

Publications and source records attributed to H Wu.

At least 775 records · Page 43Linked to original sources
PubMed1991

The three-dimensional structure of canine parvovirus and its functional implications.

The three-dimensional atomic structure of a single-stranded DNA virus has been determined. Infectious virions of canine parvovirus contain 60 protein subunits that are predominantly VP-2. The central structural motif of VP-2 has the same topology (an eight-stranded antiparallel beta barrel) as has been found in many other icosahedral viruses but represents only about one-third of the capsid protein. There is a 22 angstrom (A) long protrusion on the threefold axes, a 15 A deep canyon circulating about each of the five cylindrical structures at the fivefold axes, and a 15 A deep depression at the twofold axes. By analogy with rhinoviruses, the canyon may be the site of receptor attachment. Residues related to the antigenic properties of the virus are found on the threefold protrusions. Some of the amino termini of VP-2 run to the exterior in full but not empty virions, which is consistent with the observation that some VP-2 polypeptides in full particles can be cleaved by trypsin. Eleven nucleotides are seen in each of 60 symmetry-related pockets on the interior surface of the capsid and together account for 13 percent of the genome.

Amino Acid Sequence↗
PubMed1991

Comparison of the conformational dynamics of the (1----4)- and (1----6)-linked alpha-D-glucans using 13C-NMR relaxation.

The conformational dynamics of alpha-(1----4)- and alpha-(1----6)-glucan homooligomers in the nanosecond time domain have been compared by measuring the 13C-nmr longitudinal relaxation times T1 for carbons of the terminal and interior sugar residues. Measurements are reported on monomeric glucose and on oligomers containing up to ten glucose residues at room temperature in aqueous solution at concentrations of 3 and 20 g/dL. The carbons of terminal residues display longer relaxation times than do those of interior residues, presumably as a consequence of a greater degree of conformational mobility of the chain ends. The T1s of the reducing terminal residues of all oligomers are significantly longer than those of the corresponding nonreducing termini, a phenomenon that we associate tentatively with the anomeric equilibrium at the reducing end. Carbons of the reducing terminal residues in the beta-anomeric form relax more slowly than their alpha-anomeric counterparts. At 20 g/dL the mean T1s for carbons of the terminal and interior residues attain asymptotic behavior with increasing chain length at a chain length of about six residues, and carbons of the alpha-(1----4)-linked maltooligomers relax significantly more slowly than those of the corresponding alpha-(1----6)-linked isomaltooligomers. The T1s of both glucan series increase with decreasing concentration. This concentration dependence disappears below 3 g/dL, where the T1s of the two series of homoligomers are no longer distinguishable. This suggests that in dilute aqueous solution at room temperature viscous damping effects predominate over contributions to the T1-sensitive conformational dynamics from structural differences in the glycosidic linkage region. At 3 g/dL the approach to long chain-length asymptotic behavior is more protracted than at 20 g/dL, and the T1s of carbons of interior oligomeric residues appear to match the corresponding high-polymer behavior at a chain length of eight and greater.

Carbohydrate Conformation↗
PubMed1991

Experiences in intravenous urokinase treatment of 100 acute myocardial infarction patients.

From 1980 to 1990 we treated 100 cases of AMI with i.v. urokinase (UK). According to the way of management and the dosage administered all these cases were divided into three groups: first stage of small dosage, second stage of trial big dosage, and third stage of comprehensive dosage. 36 patients of the first stage were treated with small dosage, 1-20,000 U b.i.d. for 1 week. 75% of the UK-treated and only 17% of the control group obtained relief of pain. Decrease of elevated ST reaching base line was 50 vs 8%, and FDP increased in 94%. 22 patients of the second stage were undergoing trial of big dosage. They were subdivided into larger dosage (more than 800,000 U) and smaller dosage (less than 300,000 U) groups. From the larger dosage group, 2 patients showed definite sign of recanalization, but unexpectedly 2 patients died of cardiac rupture. Since the recanalization rate of larger dosage group was 42.9%, but no case showed sign of recanalization in smaller dosage group, we are of the opinion that the dose of 800,000 U is rational for patients with symptoms' onset less than 3 h. Cardiac rupture was thought to be mostly due to reperfusion injury. Thus we designed the third stage of comprehensive dosage of UK. In this stage we used different dosage of UK and different ways of administration in 52 patients, based on the different symptoms' onset, so as to bring the effect of UK in full play. The aim of using UK is chiefly fibrinolysis as well as improvement of blood viscosity.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1991

Binding of peptides with basic residues to membranes containing acidic phospholipids.

There are clusters of basic amino acids on many cytoplasmic proteins that bind transiently to membranes (e.g., protein kinase C) as well as on the cytoplasmic domain of many intrinsic membrane proteins (e.g., glycophorin). To explore the possibility that these basic residues bind electrostatically to monovalent acidic lipids, we studied the binding of the peptides Lysn and Argn (n = 1-5) to bilayer membranes containing phosphatidylserine (PS) or phosphatidylglycerol (PG). We made electrophoretic mobility measurements using multilamellar vesicles, fluorescence and equilibrium binding measurements using large unilamellar vesicles, and surface potential measurements using monolayers. None of the peptides bound to vesicles formed from the zwitterionic lipid phosphatidylcholine (PC) but all bound to vesicles formed from PC/PS or PC/PG mixtures. None of the peptides exhibited specificity between PS and PG. Each lysine residue that was added to Lys2 decreased by one order of magnitude the concentration of peptide required to reverse the charge on the vesicle; equivalently it increased by one order of magnitude the binding affinity of the peptides for the PS vesicles. The simplest explanation is that each added lysine binds independently to a separate PS with a microscopic association constant of 10 M-1 or a free energy of approximately 1.4 kcal/mol. Similar, but not identical, results were obtained with the Argn peptides. A simple theoretical model combines the Gouy-Chapman theory (which accounts for the nonspecific electrostatic accumulation of the peptides in the aqueous diffuse double layer adjacent to the membrane) with mass action equations (which account for the binding of the peptides to greater than 1 PS). This model can account qualitatively for the dependence of binding on both the number of basic residues in the peptides and the mole fraction of PS in the membrane.

Kinetics↗
PubMed1991

Schistosoma japonicum: some parameters affecting the development of protective immunity induced by a cryopreserved, irradiated schistosomula vaccine in guinea-pigs.

Experiments were conducted in guinea-pigs to elucidate the parameters affecting the development of protective immunity against Schistosoma japonicum induced by a cryopreserved, irradiated schistosomula vaccine such as the number of immunizations, route of injection and the use of adjuvants. Results obtained indicated that the cryopreserved, irradiated schistosomula vaccine was effective by either intradermal or intramuscular injection. One intradermal injection with BCG adjuvant resulted in an average worm reduction of 50 x 24%, only a little lower than that of a non-cryopreserved, irradiated vaccine, 53 x 55%, with no statistically significant difference between the two. By intramuscular injection the worm reduction was lower (max. 40%) whether given with or without adjuvants or in 1 or 2 injections.

Adjuvants, Immunologic↗
PubMed1991

Reduction in lactate accumulation correlates with differentiation-induced terminal cell division of leukemia cells.

Lactate accumulation in the medium and glucose utilization decreased during the induction of in vitro differentiation of mouse erythroleukemia (MEL) and human myeloid leukemia (HL-60) cells. The decrease in lactate accumulation occurred as early as 24 h after inducer treatment was initiated and occurred prior to the decrease in glucose utilization. The decrease in lactate accumulation was greater than that predicted by the decrease in glucose utilization, i.e., the ratio of glucose used glycolytically, as measured by lactate accumulation, to glucose used in other pathways ('glycolytic ratio') markedly decreased during differentiation in these cell lines. Differentiation correlated with the abrogation of the high levels of lactate accumulation first described by Warburg as characteristic of some transformed and neoplastic cells. Studies on both parental and differentiation-resistant variant MEL cell lines indicated that the changes in lactate accumulation were not dependent on the changes in glucose utilization and could be dissociated from them. Moreover, the changes in lactate accumulation only occurred in cells able to undergo differentiation-induced terminal cell division. This regulatable expression of lactate accumulation in MEL and HL-60 cells in vitro may make them useful model systems for the elucidation of the molecular mechanisms controlling lactate formation in malignant cells.

Acetamides↗
PubMed1991

Identification and characterization of a novel cytoskeleton-associated pp60src substrate.

Transformation of cells by the src oncogene results in elevated tyrosine phosphorylation of two related proteins, p80 and p85 (p80/85). Immunostaining with specific monoclonal antibodies revealed a striking change of subcellular localization of p80/85 in src-transformed cells. p80/85 colocalizes with F-actin in peripheral extensions of normal cells and rosettes (podosomes) of src-transformed cells. Sequence analysis of cDNA clones encoding p80/85 revealed an amino-terminal domain composed of six copies of a direct tandem repeat, each repeat containing 37 amino acids, a carboxyl-terminal SH3 domain, and an interdomain region composed of a highly charged acidic region and a region rich in proline, serine, and threonine. The multidomain structure of p80/85 and its colocalization with F-actin in normal and src-transformed cells suggest that these proteins may associate with components of the cytoskeleton and contribute to organization of cell structure.

Amino Acid Sequence↗
PubMed1991

Retrovirus-induced insertional mutagenesis: mechanism of collagen mutation in Mov13 mice.

The Mov13 mouse strain carries a mutation in the alpha 1(I) procollagen gene which is due to the insertion of a Moloney murine leukemia provirus into the first intron. This insertion results in the de novo methylation of the provirus and flanking DNA, the alteration of chromatin structure, and the transcriptional inactivity of the collagen promoter. To address the mechanism of mutagenesis, we reintroduced a cloned and therefore demethylated version of the Mov13 mutant allele into mouse fibroblasts. The transfected gene was not transcribed, indicating that the transcriptional defect was not due to the hypermethylation. Rather, this result strongly suggests that the mutation is due to the displacement or disruption of cis-acting regulatory DNA sequences within the first intron. We also constructed a Mov13 variant allele containing a single long terminal repeat instead of the whole provirus. This construct also failed to express mRNA, indicating that the Mov13 mutation does not revert by provirus excision as has been observed for other retrovirus-induced mutations.

Alleles↗
PubMed1991

Regulation of calcium-activated potassium efflux by neurotensin and other agents in HT-29 cells.

Neurotensin receptors have been shown previously to be coupled to polyphosphoinositide turnover and intracellular Ca2+ ([Ca2+]i) mobilization in HT-29 colonic epithelial cells (Bozou et al. Biochem. J. 264: 871, 1989; Turner et al. J. Pharmacol. Exp. Ther. 253: 1049, 1990). In this study, neurotensin was found to enhance dramatically the Ba2(+)- and tetraethylammonium chloride-sensitive K(+)-efflux rate (measured with 86Rb+) in the presence of ouabain and bumetanide, with basal efflux increasing 4.5 +/- 0.5-fold with 10 nM neurotensin. The K(+)-efflux rate, which was partially dependent on the extracellular Ca2+ concentration, was also increased by carbachol and ATP, two other [Ca2+]i-mobilizing agonists in HT-29 cells, as well as by the Ca2+ ionophores ionomycin and A23187, suggesting that the efflux was through Ca2(+)-activated K+ channels. Pretreatment of cells with neurotensin, carbachol, or ATP desensitized subsequent neurotensin-stimulated efflux by 82, 57, and 63%, respectively, confirming our previous results which indicated homologous and heterologous desensitization of the neurotensin receptor-signal transduction pathway. Pretreatment of cells with the protein kinase C activators phorbol 12-myristate 13-acetate (PMA) and mezerein did not affect [Ca2+]i mobilization or K+ efflux directly but desensitized neurotensin-stimulated efflux by greater than 80%. Pretreatment (2 h) with PMA also decreased K+ efflux in response to ionomycin by 59%, although ionomycin-induced [Ca2+]i mobilization was not inhibited. Downregulation of protein kinase C by overnight pretreatment with PMA resulted in recovery of ionomycin-stimulated efflux. These results suggest that agonist-stimulated Ca2(+)-activated K+ channels in HT-29 cells are regulated at multiple steps in the signal transduction pathway.

Adenocarcinoma↗
PubMed1991

Activation of phospholipase D by E-series prostaglandins in human erythroleukemia cells.

Phospholipase D (PLD) can be activated by a variety of receptor agonists in different cell types. However, an effect of prostaglandins (PGs) on the activity of this enzyme has not been demonstrated previously. In this study, we found that PGE1 could stimulate PLD in human erythroleukemia cells, as measured by phosphatidylethanol formation, with an ED50 of 3.5 x 10(-7) M. PGE2 was also active, but other PGs including prostacyclin, PGD2 and PGF2, had no effect. PGE1 also elicited cyclic AMP production over the same concentration range that activated PLD. However, it is unlikely that cyclic AMP per se is responsible for PGE-induced PLD activation, because PLD could be substantially activated by PGE2 at concentrations (0.1-1 microM) which did not stimulate cyclic AMP production. Furthermore, no increase of phosphatidylethanol formation could be observed when cells were treated with other adenylyl cyclase-activating agents such as prostacyclin, forskolin and vasoactive intestinal peptide. In Ca+(+)-free medium, PLD activation by PGE1 and PGE2 was greatly reduced, indicating that their effect was through a Ca+(+)-dependent pathway. Pretreatment of cells with pertussis toxin abolished PGE1- and PGE2-stimulated PLD activity, implying the involvement of a G protein in the PGE-mediated signal transduction pathway. Our results not only indicate that E-series PGs may initiate some of their cellular effects through a novel pathway, activation of PLD, but also suggest that PGE-stimulated PLD activity in human erythroleukemia cells is Ca+(+)-dependent and is regulated via a pertussis toxin-sensitive G protein.

Calcium↗
PubMed1991

[Protective effect of Glycyrrhiza uralensis Fisch and its extracts on the chronic desensitization of beta-adrenoceptors in guinea pigs].

Histamine-induced wheezing test is conjunction with radioligand binding assay showed that after long-term administration of isoprenaline the reactivity and R, value (total receptor binding sites) of beta-adrenoceptors in the lung tissue of guinea pigs were reduced. The decoction of Glycyrrhiza uralensis Fisch or its extractive LX56 given intraperitoneally could prevent these changes, but the decoction per os or glycyrrhetinic acid given intraperitoneally could not.

Animals↗
PubMed1991

[The effect of suturing on Langerhans' cells of the ocular surface].

Langerhans' cells (LC) exist on the ocular epithelial surface and participate in immunologic and non-immunologic reactions. On the corneal surface, LC are distributed in the limbal area, but not in central cornea. Placement of a suture in central cornea induced increase of LC and their migration to central cornea, only to diminish after removal of the suture, indicating participation of LC in non-immunological reactions of the corneal surface. The role of LC in immunologic reactions was also discussed.

Animals↗
PubMed1991

Glycation of lysozyme in a restricted water environment.

Fast atom bombardment mass spectrometry (FAB) was used to determine the glycation sites of lysozyme in a restricted water environment. A 30-day incubation at 25 degrees C, and 65% relative humidity (R.H.) resulted in glycation at lysine-1 while a much shorter (3-day) incubation at 50 degrees C and 65% R.H. resulted in diglycation at lysine-1 as well as glycation at lysine-13 and lysine-33.

Amino Acid Sequence↗
PubMed1991

[High-yield agronomic measures of Curcuma longa L].

A method of orthogonal conic combinatorial design has been employed in the study of high-yield agronomic measures of C. longa. The results show that by increasing plants/mu and postponing sowing date, the yield is 50% higher than before, mathematical model of yield on plants/mu and sowing date were established, which can be used to predict the yield and explore optimal agronomic measures.

Plants, Medicinal↗