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Biomedical subjects

J Ding

Publications and source records attributed to J Ding.

At least 253 records · Page 14Linked to original sources
PubMed1993

Neutrophils stimulated with a chemotactic peptide or a phorbol ester exhibit different alterations in the activities of a battery of protein kinases.

Protein kinases in neutrophils that undergo changes in activity during cell stimulation have been investigated by two recently described procedures. These methods are based on the ability of renatured kinases to undergo autophosphorylation or to phosphorylate protein substrates fixed in gels. Using these techniques, we report that neutrophils contain a battery of protein kinases with molecular masses of 65-61 kDa (termed "group A kinases") that are rapidly activated upon stimulation of the cells with the chemotactic peptide N-fMet-Leu-Phe (fMLP). Activity was maximal within 30 s with this stimulus and returned to the basal level seen in unstimulated cells within 3 min. In contrast, stimulation of neutrophils with 4 beta-phorbol 12-myristate 13-acetate resulted in a diminution of these kinase activities. Treatment of neutrophils with antagonists of type 1 and 2A protein phosphatases (calyculin A, okadaic acid) inhibited the activation of the group A kinases by fMLP, whereas norokadanone, an analog of okadaic acid that is a poor inhibitor of protein phosphatases, had no effect. Exposure of neutrophils to calyculin A alone resulted in the activation of several additional protein kinases with molecular masses different from the group A kinases. These data indicate that the signal transduction pathways of neutrophils are likely to be far more complicated than previously appreciated and involve a number of uncharacterized protein kinases.

Animals↗
PubMed1993

The role of expectations in patients' reports of post-operative outcomes and improvement following therapy.

Outcomes research typically focuses on the technical capabilities associated with treatment that predicts patients' post-therapy outcomes adjusting for health-related factors. Research on the ability of placebo therapy to alter outcomes suggests that a patient's expectations about therapy can also influence outcomes. Few studies have examined the effects of expectations and their implications for assessing outcomes. This study followed 348 patients who had surgery for benign prostatic hyperplasia. Four hypotheses are tested: whether positive expectations about improvement influence: 1) patients' postoperative reports of symptoms; 2) their belief that they have improved; 3) their overall health after treatment; and 4) whether these effects persist during the year following treatment. Using step-wise regression to control for sociodemographic and clinical factors, we found positive expectations did not appear to strongly influence a patient's report of postoperative symptoms or their overall health. However, we found strong support for positive expectations increasing the likelihood of reporting they felt better after surgery, even after controlling for symptom changes. This effect persisted throughout the postoperative year. We conclude that positive expectations result in a more optimistic view of improvement after surgery rather than altering reports of outcomes or health.

Adult↗
PubMed1993

Reticuloendothelial system function following acute liver failure induced by 90% hepatectomy in the rat.

Sepsis and bacterial infections are frequent complications of acute liver failure and following major liver resection. The mechanisms underlying this phenomenon are unclear. In this study, RES function and blood clearance of radiolabelled E. coli was immediately impaired following 90% hepatectomy, although the reduction in liver volume resulted in an increase in splenic (temporary) and pulmonary (persisting) uptake. A significant correlation between liver function and host RES function was observed. The uptake capacity of the RES in the liver remnant and spleen did not correlate with subserosal blood flow. The uptake in the brain gradually increased with time, paralleling an increased leakage across the blood-brain barrier. Thus, a significantly impaired RES function resulted from experimental 90% hepatectomy-induced acute liver failure, which might explain the high incidence of septic events in the clinical situation.

Animals↗
PubMed1993

[Investigations on hepatitis C virus infection among heterosexuals with multiple partners and patients with sexually transmitted diseases].

The seroprevalence of antibody against hepatitis C virus (HCV) was assessed by an enzyme-linked immunosorbent assay (ELISA) in 110 heterosexually transmitted diseases (STDs), 98 heterosexuals with multiple partners, and 107 blood donors. The serum samples were also tested for hepatitis B virus surface antigen (HBsAg) and antibody against hepatitis B core antigen (anti-HBc). Of the patients with STDs 12.7% (13/110) were anti-HCV antibody positive; of heterosexuals with multiple sexual partners, 4.1% (4/98) positive; of blood donors, 1.87% (2/107) positive. Among the 18 cases of HCV infection, 3 were positive for HBsAg and 10 were positive for anti-HBc antibody. There was no relationship among HCV infection, sex and age in observed objects. From the present data, we can conclude that HCV infection should not be ignored in heterosexuals with multiple partners and patients with STDs, and the risk factor for HCV infection appeared to be associated with a history of STDs and with HBV infection.

Adolescent↗
PubMed1993

Kinetic study and modelling on L-arginine fermentation.

The batch fermentation of L-arginine using Corynebacterium crenatum L-arginine-producing mutant 971.1 was kinetically studied in a 2.6 L fermentor for the following purposes: kinetic classification of L-arginine fermentation by the comparison of the two-phases of specific growth rates; modelling of the L-arginine fermentation, and discussion about the effects of oxygen supply on the conversion rate of glucose to L-arginine, by comparing the fraction of glucose-consumption for L-arginine-formation alpha p and the fraction of glucose-consumption for cell-growth alpha x under different oxygen transfer coefficients kLa. The kinetic fermentative behavior of the strain 971.1 in L-arginine formation, which was related to the velocity and effectiveness of the metabolism of the cell, was mathematically analyzed.

Arginine↗
PubMed1992

Cloning and characterization of a cDNA coding for the alpha-subunit of a stimulatory G protein from Schistosoma mansoni.

Guanine nucleotide-binding proteins (G proteins) mediate signals between serotonin receptors and adenylate cyclase in Schistosoma mansoni. A bovine Gs alpha cDNA probe was used to isolate a cDNA clone, SG12, encoding the entire alpha-subunit of a G protein of S. mansoni. The cDNA is 1897 base pairs long, contains an open reading frame of 1137 base pairs, and codes for a deduced protein of 379 amino acids. The putative protein encoded by the clone has an exact amino acid match with bovine Gs alpha of 65% and a 78% match when conserved amino acid substitutions are considered. In contrast, the exact and conserved matches of the schistosome alpha-subunit with bovine Gi are 41 and 61%, respectively. A comparison of the deduced amino acid sequence of SG12 with a variety of different G alpha proteins indicates that all the major structural features characteristic of a Gs alpha protein are present in the S. mansoni gene. The schistosome clone contains the putative site for ADP-ribosylation by cholera toxin found in Gs alpha but does not contain the ADP-ribosylation site for pertussis toxin present in Gi alpha. The amino acids are completely conserved at the GTP-binding sites. On a Northern blot, the cDNA hybridizes to a major band of 3.1 kilobases in RNA from adult schistosomes. The message appears to be absent in miracidia and cercariae, but a faint 3.1-kilobase band is visible in the early schistosomule stage preceding adulthood. This evidence, when added to previous biochemical data, indicates that the expression of this gene is developmentally controlled.

Amino Acid Sequence↗
PubMed1992

Structure of HIV-1 reverse transcriptase/DNA complex at 7 A resolution showing active site locations.

AIDS, caused by human immunodeficiency virus (HIV), is one of the world's most serious health problems, with current protocols being inadequate for either prevention or successful long-term treatment. In retroviruses such as HIV, the enzyme reverse transcriptase copies the single-stranded RNA genome into double-stranded DNA that is then integrated into the chromosomes of infected cells. Reverse transcriptase is the target of the most widely used treatments for AIDS, 3'-azido-3'-deoxythymidine (AZT) and 2',3'-dideoxyinosine (ddI), but resistant strains of HIV-1 arise in patients after a relatively short time. There are several nonnucleoside inhibitors of HIV-1 reverse transcriptase, but resistance to such agents also develops rapidly. We report here the structure at 7 A resolution of a ternary complex of the HIV-1 reverse transcriptase heterodimer, a monoclonal antibody Fab fragment, and a duplex DNA template-primer. The double-stranded DNA binds in a groove on the surface of the enzyme. The electron density near one end of the DNA matches well with the known structure of the HIV-1 reverse transcriptase RNase H domain. At the opposite end of the DNA, a mercurated derivative of UTP has been localized by difference Fourier methods, allowing tentative identification of the polymerase nucleoside triphosphate binding site. We also determined the structure of the reverse transcriptase/Fab complex in the absence of template-primer to compare the bound and free forms of the enzyme. The presence of DNA correlates with movement of protein electron density in the vicinity of the putative template-primer binding groove. These results have important implications for developing improved inhibitors of reverse transcriptase for the treatment of AIDS.

Base Sequence↗
PubMed1992

Structure of ribonuclease T1 complexed with zinc(II) at 1.8 A resolution: a Zn2+.6H2O.carboxylate clathrate.

In order to study the inhibitory effect of Zn2+ on ribonuclease T1 [RNase T1; Itaya & Inoue (1982). Biochem. J. 207, 357-362], the enzyme was cocrystallized with 2 mM Zn2+, pH 5.2, from a solution containing 55% (v/v) 2-methyl-2,4-pentanediol. The crystals are orthorhombic, P2(1)2(1)2(1), a = 48.71 (1), b = 46.51 (1), c = 41.14 (1) A, Z = 4, V = 93203 A3. The crystal structure was determined by molecular replacement and refined by restrained least-squares methods based on Fhkl for 8291 unique reflections with Fo greater than or equal to 1 sigma (Fo) in the resolution range 10 to 1.8 A and converged at a crystallographic R factor of 0.140. The Zn2+ is not bonded to the active site of RNase T1, probably because the His40 and His92 side chains are protonated. Zn2+ occupies the same site as Ca2+ in a series of crystal structures of free and nucleotide-complexed RNase T1. It is coordinated to Asp15 carboxylate and to six water molecules forming a dodecahedron of square antiprismatic form. The Zn2+...O distances are approximately 2.5 A, suggesting that Zn2+ is clathrated and not coordinated, which would require distances of 2.0 A.

Amino Acid Sequence↗
PubMed1992

Effects of antagonists of protein phosphatases on superoxide release by neutrophils.

Neutrophils stimulated with 4 beta-phorbol 12-myristate 13-acetate (PMA) release large quantities of superoxide (O2-) and exhibit phosphorylation of two proteins with molecular masses of 47(p47) and 49 kDa (p49). Addition of inhibitors of protein kinases (e.g. 1-(5-isoquinolinylsulfonyl)-2-methylpiperazine (H-7)) to these cells after stimulation with PMA results in the loss of 32P from these proteins and a rapid cessation of O2- release (e.g. Heyworth, P. G., and Badwey, J. A. (1990) Biochim. Biophys. Acta 1052, 299-305). In this paper we report that antagonists of type 1 and 2A protein phosphatases (okadaic acid, calyculin A) prevented both the loss of 32P from p47 and the termination of O2- release in stimulated neutrophils treated with H-7. Calyculin A also caused a remarkable hyperphosphorylation of a number of proteins in neutrophils and increased O2- release from these cells in response to a suboptimal amount of PMA. Enzymes present in both the soluble and particulate fractions of neutrophils catalyzed the near complete dephosphorylation of 32P-labeled p47 and p49 bound to Immobilon-P membranes. Dephosphorylation of these blotted phosphoproteins occurred at physiological rates and was inhibited by okadaic acid and calyculin A. These data strongly suggest that p47 undergoes a continual cycle of phosphorylation and dephosphorylation throughout the period of O2- release when PMA is the stimulus. Moreover, we show that antagonists of type 1 and 2A protein phosphatases block dephosphorylation of p47 both in vivo and in vitro, indicating that these enzymes may modulate O2- release under certain circumstances.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1992

Protein and nuclear changes in pig eggs at fertilization.

The nuclear restructuring that occurs between insemination and full pronuclear formation in pig eggs is accompanied by posttranslational changes to specific egg proteins. Sperm penetration begins in vitro at 3 hr postinsemination (hpi). By 5 hr, decondensing sperm heads and anaphase II plates are observed in 50% of eggs, and, by 8 hpi, both male and female pronuclei have formed. Three consistent changes to the pattern of newly synthesised proteins are triggered in this period; they affect the 46K, 25K, and 22K polypeptides. Changes are also triggered in the 180-200K polypeptides and in the 14K polypeptides, but these are highly variable. The same changes in the prefertilization pattern were observed when prelabelled eggs were used and new protein synthesis was suppressed. The first and most abrupt change involves the apparent catabolic elimination of a group of 46K unphosphorylated polypeptides (pl 7.3-6.4), whose synthesis was greatest before germinal vesicle breakdown but declined slowly in the final phase of maturation, then declined precipitously after activation. Ageing (beyond maturation) also leads to the disappearance of these polypeptides. The progressive disappearance of a set of 25K polypeptides and the concomitant appearance of a dominant 22K polypeptide is the most characteristic fertilization-induced modification to porcine egg proteins. These modifications begin within 1 hr of sperm penetration or activation, are specific to the pig, and involve heavily phosphorylated polypeptides (25K, pl 6.7-6.0) whose synthesis is begun in the early metaphase I stage. Dual ([35S] and [32P]) labelling, protein blocking experiments, and use of alkaline phosphatase suggest that dephosphorylation selectively affects these 25K polypeptides and is mainly or wholly responsible for converting them (completely within 6 hr) to a single, new (22K, pl 7.6) species that is positively charged. The 25K/22K polypeptide modification has a close temporal relationship with the formation of the male and female pronuclei.

Animals↗
PubMed1992

Effects of protein synthesis on maturation, sperm penetration, and pronuclear development in porcine oocytes.

In vitro matured porcine oocytes were used to test the importance of protein synthesis for sperm penetration, the second meiotic division, and pronuclear development. Experiments were carried out to measure rates of protein synthesis in the presence of protein synthesis inhibitors (35 microM or 350 microM cycloheximide or a combination of inhibitors) (study 1); to test for sperm penetration and pronuclear development when protein synthesis was inhibited during fertilization (study 2); to test for oocyte meiosis, sperm penetration, and female and male pronuclear development when protein synthesis was inhibited during maturation (oocyte maturation in vitro with addition of inhibitor at 0, 24, or 36 hr of culture) (study 3); and to analyze the changes in the pattern of protein synthesis during these phases. Sperm penetration, oocyte meiosis, and female pronuclear development were not affected by the total inhibition of protein synthesis during fertilization. By contrast, inhibiting protein synthesis during maturation severely impaired the completion of meiosis and pronuclear development. Although inhibition of protein synthesis after 36 hr of maturation culture did not totally block male pronuclear development (MPN), the rate of MPN formation was lower than for controls (52% vs. 72%, P less than 0.05). However, protein synthesis was absolutely essential between 24 and 36 hr for the formation of MPN after decondensation. This period of maturation coincided with the dominant phase of protein reprogramming in the oocyte.

Animals↗
PubMed1992

Spindle cell haemangioendothelioma: probably a benign vascular lesion not a low-grade angiosarcoma. A clinicopathological, ultrastructural and immunohistochemical study.

Ten cases of spindle cell haemangioendothelioma (SCH) were analysed clinicopathologically, including an immunohistochemical survey of seven cases and ultrastructural observations on one. There were seven females and three males, ranging from 16 to 76 years of age. All but one lesion developed on the extremities, predominantly on the hands and feet. Six of the ten patients presented multiple nodules or papules which gradually increased in size and number over a long duration. Among them, four patients had undergone operations twice or more, but no metastatic foci were recognized. Histologically, the lesions were composed of dilated vascular spaces and a proliferation of bland-appearing spindle cells and interspersed epithelioid endothelial cells. Ultrastructural and immunohistochemical studies demonstrated that the spindle cells were mainly made up of fibroblastic cells admixed with pericyte-like cells and macrophages. Smooth muscle cells and primitive mesenchymal cells were also present. The clinical and microscopic features suggest that SCH may be a benign vasoformative lesion of a heterochronological multicentric origin.

Adolescent↗
PubMed1992

Follicular heterogeneity and oocyte maturation in vitro in pigs.

Experiments were conducted to confirm that co-culture of follicular shells and immature pig oocytes improved the rate of male pronuclear (MPN) formation and to test the hypothesis that the maturational state of the follicle used in co-culture would significantly affect the quality of oocytes matured in vitro. In a preliminary experiment, co-culture of oocyte complexes with follicular shells did not affect nuclear maturation, slightly inhibited penetrability (p = 0.04) but greatly enhanced (p = 0.0004) MPN rate. In the main experiment, oocyte complexes (10-15 per dish), obtained from follicles 36 h after eCG injection of prepubertal gilts, were co-cultured with single 36-h small (3.5-5.0 mm), 36-h large (6-9 mm), 72-h small (4-7 mm), or 72-h large (7.5-11.0 mm) follicular shells prior to insemination. MPN formation in penetrated oocytes was significantly affected by follicular size (small: 60.14% vs. large: 72.08%, p = 0.014) but not by time of recovery (36 h: 72.32% vs. 72 h: 59.90%, p = 0.39). Overall, MPN formation rate was significantly correlated with follicular diameter (r = 0.45, p = 0.005), follicular fluid progesterone (r = 0.37, p = 0.02), and estradiol (r = 0.40, p = 0.01), and to the ratios of follicular fluid progesterone:testosterone (r = 0.39, p = 0.018) and follicular fluid estradiol:testosterone (r = 0.43, p = 0.007). There were no simple correlations between rate of MPN formation and steroid concentrations and their ratios in culture media collected at the completion of culture.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Mass culture of anchorage-dependent animal cells with newly born calf skin collagen membrane and microcarrier.

It was shown that collagen substrate enhances the growth as well as the differentiation of many cells in culture. Collagen is one of the major fibrous proteins of animal bodies and the pure collagen used in this experiment was extracted from the newly born calf skin by chemical and biochemical methods. The analytical results obtained by ion-exchange chromatography and electrophoresis showed that the main components of denatured collagen were alpha monomers and beta dimers. The collagen and denatured collagen membranes were prepared by coating their solution on peteri dishes. Various types of cells were cultured on these membranes after being irradiated by ultraviolet ray. The denatured collagen was proved a good substratum for culturing anchorage dependent cells. A denatured collagen (gelatin) microcarrier, GT-2 was obtained by cross-linking gelatin with glutaraldehyde in a suspension polymerization process. These microcarriers were used successfully to culture various anchorage-dependent cells such as Vero, CHO, Bowes and fish cells in varying scales, including T-flasks, spinning bottles, revolving bottles and 1.5 l and 20 l bioreactors.

Animals↗