Biomedical subjects
Publications and source records attributed to Q Lu.
This paper reports a study of the c-erbB2 oncoprotein (by immunohistochemical method) in 97 gastric carcinoma resected at Shanghai Cancer Hospital in 1991. In 30 out of the 97 cases (30.9%) c-erbB2 was positive and its expression was higher among patients with lymph node metastasis (P < 0.05). Univariate and multivariate analyses indicated that c-erbB2 expression betokened poor prognosis.
In recent years there has been considerable interest concerning the role of hepatocellular Ca2+ overload which probably was a major factor in hepatic ischemia/reperfusion injury. We studied the effect of radix salviae miltiorrhizae (RSM) on cytosolic free calciumion concentration [(Ca2+)i](nM) in isolated hepatocytes in rats and patients with ischemia reperfusion by microflurometry using fluorescent (Ca2+)i indicator Fura-2/AM. Changes of lipid peroxide free radical (ROO.) signal ranges with in the liver tissue by ESR technique and those of hepatocellular ultrastructure by electronmicroscope were also observed. The results showed that RSM reduced levels of (Ca2+)i and ROO. Ymax (mm) ESR signal rangs. RSM had an effect on protecting hepatocytes against ischemia/reperfusion injury as a useful receptor-operated calcium channels (ROC) blocker.
Artificial musk-raw material, using as a substitute for traditional Chinese medicine musk, a new drug of class I was assessed for mutagenicity. The micronucleus rates of polychromatocyte in the bone marrow of mice were 2.8, 1.3 and 1.0/1000 when the treated dosage was 1800, 700 and 350 mg/kg. The results of Ames test for the strains TA97, TA98, TA100 and TA102 were negative with and without S9 mix when the concentration of artificial musk was 625, 1,250, 2,500 and 5,000 micrograms/plate, respectively. The chromosome aberration rates were 1.0, 0.8, 1.2% when the treated dosage was 360, 180, 90 mg/kg, respectively. The above results proved that no mutagenicity was found for artificial musk.
AIM: To study the action of quercetin (Que) on inhibiting platelet aggregation. METHODS: Active oxygen free radicals produced by xanthine/xanthine oxidase (Xan/XO) reaction was used, platelet aggregation was determined by the turbidimetric method, and the Xan/XO oxyradicals generating reaction by luminol-dependent chemiluminescence (Che) method. RESULTS: Active oxygen free radicals enhanced the platelet aggregation induced by ADP 1.6 mumol.L-1. The rate of maximal aggregation increased from 29%-38% for ADP to 59%-70% for ADP + Xan/XO. The enhancement was abolished by the treatment of platelet-rich plasma (PRP) with Que 650 mumol.L-1 or hydrocortisone (Hyd) 900 mg.L-1. Both Que and Hyd scavenged the active oxyradicals in vitro. The Che was decreased by 75.7% (Que 4 mumol.L-1) and 79.0% (Hyd 900 mg.L-1) as compared with control. CONCLUSION: Active oxygen free radicals participated in the platelet aggregation, and scavenging oxyradicals by Que was one of mechanisms of inhibiting platelet aggregation.
AIM: To study the effect of GABA on cold restraint-induced gastric ulcer (CRGU) and its mechanism. METHODS: CRGU was produced in adult male mice at 1 degree C in cold room under restraint for 1 h. The ulcer index indicated the severity of gastric mucosa lesion. Gastric mucin was determined with alcian blue dye. RESULTS: GABA 2 mumol (i.c.v.) accelerated CRGU, Bicuculline (Bic) 0.2 mumol (i.c.v.) did not affect CRGU, whereas Baclofen (Bac) 4 mumol (i.c.v.) exacerbated CRGU. Bic did not modify the exacerbation of CRGU by GABA and Bac. Atropine (Atr) 0.2 mg.kg-1 (s.c.) and Phentolamine (Phen) 2.5 mg.kg-1 inhibited CRGU, and abolished the exacerbation of CRGU by GABA. Cold restraint (CR) decreased the amount of the gastric mucin, but GABA 2 mumol had no effect on CR gastric mucin. CONCLUSION: While GABA-B receptor in brain was activated, exogenous GABA exacerbated CRGU via vagal and sympathetic nerves, bearing no relation to decrease of the gastric mucin or weakening of the gastric mucosal barrier.
Nucleoside diphosphate (NDP) kinase is a key enzyme in the control of cellular concentrations of nucleoside triphosphates, and has been shown to play important roles in various cellular activities such as developmental control, signal transduction and metastasis in eukaryotic systems. In this study, the gene for NDP kinase of Escherichia coli (ndk) was disrupted and surprisingly found to be dispensable without any discernible effects on cell growth or morphology. However, a mutator phenotype was found in ndk-disruption strains; frequencies of spontaneous mutations to rifampicin resistance and nalidixic acid resistant significantly increased. A higher frequency in reversion mutations was observed with use of an amber mutation in the kanamycin-resistance gene in an ndk-disruption strain. Imbalance in dNTP pools, in particular a significant increase of the dCTP content was observed, which is likely to result in the higher spontaneous mutation rates. These results suggest that NDP kinase, although not essential, plays an important role in the appropriate balance of intracellular dNTP pools to maintain a high DNA replication fidelity. Strains with ndk- pykA- pykF- as well as ndk- scs- were constructed without any discernible effect on cell growth, indicating that there is yet another enzyme(s) catalyzing nucleoside triphosphate synthesis, in addition to NDP kinase, pyruvate kinases and succinyl CoA synthetase.
The regulatory region of Drosophila melanogaster hsp26 includes a positioned nucleosome located between the two DNase I hypersensitive (DH) sites that encompass the critical heat shock elements (HSEs). To test the role of this nucleosome in regulated expression, transgenic flies containing hsp26-lacZ fusion genes with alterations in the nucleosome-associated region have been generated. The positioned nucleosome is associated with a DNA sequence that does not itself contain any critical regulatory elements for heat shock-inducible expression. The nucleosome-associated sequence can be deleted, reversed, duplicated or replaced by a random sequence with no significant effect on DH site formation and gene expression. Analyses of hsp26 and hsp70 transgenes with spacing changes within the promoter region indicate that the location of the (CT)n.(GA)n elements dictates the location of DH site formation. Wrapping the DNA between the regulatory elements around a nucleosome is as effective for gene expression as placing the regulatory elements close to each other. A loss of inducible gene expression was observed when the nucleosome-associated DNA was replaced with sequences which appear to misdirect nucleosome placement. The results indicate considerable flexibility in the spacing between DH regulatory sites.
delta 1-Pyrroline-5-carboxylate synthetase (P5CS) catalyzes the first two steps in proline biosynthesis in plants. The Vigna aconitifolia P5CS cDNA was expressed in Escherichia coli, and the enzyme was purified to homogeneity. The Vigna P5CS exhibited two activities, gamma-glutamyl kinase (gamma-GK) and glutamic acid-5-semialdehyde (GSA) dehydrogenase. The gamma-GK activity of the P5CS was detected by the hydroxamate assay and by a [14C]glutamate assay. The native molecular mass of the P5CS was 450 kDa with six identical subunits. The Vigna P5CS showed a Km of 3.6 mM for glutamate, while the Km for ATP was 2.7 mM. The gamma-GK activity of the P5CS was competitively inhibited by proline, while its GSA dehydrogenase activity was insensitive to proline. In addition, a protein inhibitor of the P5CS was observed in the plant cell. Western blot showed that the level of the P5CS was enhanced in Vigna root under salt stress. A single substitution of an alanine for a phenylalanine at amino acid residue 129 of the P5CS resulted in a significant reduction of proline feedback inhibition. The 50% inhibition values of gamma-GK activity of the wild type and the mutant P5CS were observed at 5 mM and 960 mM proline, respectively. The other properties of the mutant P5CS remained unchanged. These results may allow genetic manipulation of proline biosynthesis and overproduction of proline in plants for conferring water stress tolerance.
Among higher plants, soybean is unique in that biochemically it has been characterized as having two constitutive nitrate reductase (cNR) isoforms and one substrate-inducible nitrate reductase (iNR) isoform in leaves. All three NR isoforms are expressed in cv. Williams 82 while the nr1 mutant expresses only the iNR isoform. The genetic and molecular mechanisms for regulation of these isoforms have not been elucidated. We describe here the isolation, by reverse transcription-polymerase chain reaction (RT-PCR), of two cDNA clones encoding soybean NR. They were designated as iNR1 and iNR2, respectively, since both were inducible by nitrate. The iNR1 and iNR2 cDNAs cover total encoding regions of 2661 and 2673 nucleotides, respectively. The iNR1 clone shows a 12 bp deletion at the 5' end, relative to iNR2. They show overall similarity of 89% at the nucleotide level, and 87% at the amino acid level. Like all plant NRs cloned so far, deduced amino acid sequences between iNR1 and iNR2 show greatest variation at the N-terminal region while no difference was observed at the C-terminus. Soybean iNR mRNAs were found to be different from those of maize and tobacco in response to tungsten inhibitor treatment, since the inhibitor decreased the steady-state levels of mRNA for soybean iNR and for NiR. Using the same 5' regions of both cDNAs as the probes, Southern blot analysis of genomic DNA revealed differences in organization between iNR1 and iNR2. The genomic DNA from wild-type Williams 82 soybean was shown to have three Eco RI fragments while the nr1 mutant lacked an 8 kb fragment when probed with iNR1 cDNA. Likewise, the nr1 mutant lacked three Hae III restriction fragments when probed with iNR1 cDNA. When probed with iNR2, both wildtype and nr1 mutant showed one identical Eco RI band and two identical Hae III bands. In northern blots, the steady-state level of iNR1 mRNA was similar for the nr1 mutant and the wild-type parent after 20 to 48 h induction by nitrate. Based on the Eco RI and Hae III restriction enzyme digestion patterns observed in Southern blot analysis of soybean DNA, it is concluded that in soybean iNR1 is encoded by a small multiple gene family and iNR2 is a single gene.
BACKGROUND: Inhaled nitric oxide, a selective pulmonary vasodilator, in combination with intravenous almitrine, a selective pulmonary vasoconstrictor, markedly improves arterial oxygenation in 50-60% of patients with acute lung injury. The goal of this study was to assess dose response of inhaled nitric oxide with and without almitrine in patients with acute respiratory distress syndrome responding to nitric oxide. METHODS: Six critically ill patients (aged 44 +/- 7 yr) were studied during early stage of their acute respiratory failure (Murray score: 2.6 +/- 0.1). All responded to 15 parts per million (ppm) of inhaled nitric oxide by an increase in Pao2 of at least 40 mmHg at FIo2 1. Hemodynamic and respiratory parameters were recorded continuously from pulmonary artery and systemic catheters. Inspiratory, expiratory, and mean intratracheal nitric oxide concentrations were monitored continuously using a fast response time chemiluminescence apparatus (NOX 4000, Sérès, Aix-en-provence, France). On day 1, 6 inspiratory concentrations of nitric oxide were randomly administered: 0.15, 0.45, 1.5, 4.5, 15, and 45 ppm to determine the dose response of inhaled nitric oxide on Pao2, pulmonary shunt, mean pulmonary artery pressure, and pulmonary vascular resistance index. On day 2, a continuous intravenous infusion of almitrine at a dose of 16 micrograms.kg-1.min-1 was administered and dose response to inhaled nitrix oxide was repeated according to the same protocol as during day 1. A constant FIo2 of 0.85 was used throughout the study. RESULTS: Nitric oxide induced a dose-dependent increase in Pao2 for inspiratory nitric oxide concentrations ranging between 0.15 and 1.5 ppm. Almitrine increased Pao2/FIo2 from 161 +/- 30 to 251 +/- 45 mmHg (P < 0.001) and pulmonary vascular resistance index from 455 +/- 185 to 527 +/- 176 dyn.s.cm-5.m2 (P < 0.05), and decreased pulmonary shunt (Qs/QT) from 35 +/- 2 to 33 +/- 3% (P < 0.001). During almitrine combined with nitric oxide, a dose-dependent increase in Pao2 was observed for inspiratory nitric oxide concentrations ranging between 0.15 and 1.5 ppm. Almitrine plus nitric oxide 1.5 ppm increased Pao2/FIo2 from 161 +/- 30 to 355 +/- 36 mmHg (P < 0.001), decreased Qs/QT from 35 +/- 2 to 24 +/- 2% (P < 0.001), pulmonary vascular resistance index from 455 +/- 185 to 385 +/- 138 dyn.s.cm-5.m2 (P < 0.05), and mean pulmonary artery pressure from 31 +/- 4 to 28 +/- 4 mmHg (P < 0.001). CONCLUSIONS: In 6 patients with early acute respiratory distress syndrome and highly responsive to inhaled nitrix oxide, the administration of intravenous almitrine at a concentration of 16 micrograms.kg-1.min-1 induced an additional increase in Pao2. Dose response of nitric oxide was not changed by the administration of almitrine and a plateau effect was observed at inspiratory nitric oxide concentrations of 1.5 ppm.
OBJECTIVE: The goal of the current study was to directly assess the role of loss of mucosal barrier function in nutritionally induced bacterial translocation. BACKGROUND: Parenteral and certain elemental enteral diets have been shown to promote bacterial translocation. The mechanisms underlying this observation, especially the question of whether nutritionally induced bacterial translocation is primarily related to loss of intestinal barrier function, versus an impaired immune system, remain to be fully elucidated. METHODS: Bacterial translocation was measured in vivo, ileal mucosal membranes were harvested, and their electrophysiologic properties and barrier function were measured ex vivo in the Ussing chamber system 7 days after receiving total parenteral nutrition solution parenterally (IV-TPN) or enterally (elemental diet). Chow-fed rats served as control subjects. RESULTS: The incidence of bacterial translocation was significantly increased both to the mesenteric lymph nodes in vivo and across the in vitro Ussing chamber-mounted ileal mucosal membranes of the elemental diet-fed and IV-TPN-fed rats. The magnitude of Escherichia coli and phenol red transmucosal passage in the Ussing chamber was significantly higher in the IV-TPN-fed rats than in the elemental diet-fed or chow-fed animals. The potential differences across the ileal membrane were similar between the three groups at all time points. However, the specific resistances of the ileal membranes of the IV-TPN and elemental diet groups were significantly less than the chow-fed animals, indicating increased membrane permeability. CONCLUSIONS: Loss of intestinal barrier function plays a major role in nutritionally induced bacterial translocation, and the loss of mucosal barrier function to both E. coli and phenol red appeared greater in the IV-TPN than the elemental diet-fed rats.
OBJECTIVE: The mechanism by which hemorrhagic shock injures the gut and leads to the translocation of bacteria remains incompletely determined. Since increased free cellular calcium levels and phospholipase A2 activity can lead to cellular injury and both have been documented in certain shock states, the hypothesis that calcium or phospholipase A2 may play a role in hemorrhagic shock-induced gut mucosal injury and bacterial translocation was tested. DESIGN: Prospective animal study with concurrent controls. SETTING: Small animal laboratory. SUBJECTS: Fifty-seven male Sprague-Dawley rats weighing 250 to 350 g. INTERVENTIONS: Five groups of rats were tested utilizing a nonlethal hemorrhagic shock model (mean arterial pressure of 30 mm Hg for 30 mins). These groups included: a) sham-shock, b) shock, c) shock plus quinacrine (inhibitor of phospholipase A2), d) shock plus diltiazem (calcium-channel blocker) administered 5 mins before hemorrhage, and e) shock plus diltiazem administered at the end of shock period and before resuscitation. At 24 hrs postshock or sham-shock, the animals were killed, the mesenteric lymph node and cecum were cultured and the gut was examined histologically. MEASUREMENTS AND MAIN RESULTS: The occurrence rate of shock-induced bacterial translocation (90%) was significantly reduced in rats receiving quinacrine (27%) or preshock diltiazem (21%) (p < .05), but not postshock diltiazem (63%). Bacterial translocation did not occur in sham-shocked rats. The same amount of blood withdrawal was needed between all groups of rats to induce and maintain shock. Quinacrine and diltiazem administration largely prevented shock-induced ileal and cecal mucosal injury. CONCLUSIONS: The observation that quinacrine and preshock diltiazem limited the extent of shock-induced mucosal injury and bacterial translocation indicate that calcium and phospholipase A2 are involved in the pathogenesis of shock-induced mucosal injury and bacterial translocation. The fact that preshock but not postshock diltiazem was protective indicates that the process leading to shock-induced calcium-mediated tissue injury and bacterial translocation was initiated during the ischemic rather than the reperfusion period. However, since neither quinacrine nor diltiazem was fully protective, other factors, such as oxidants, are also likely to be involved in the pathogenesis of shock-induced mucosal injury and bacterial translocation.
Nucleoside diphosphate (NDP) kinase from Escherichia coli was purified to homogeneity and was crystallized. Gel filtration analysis of the purified enzyme indicated that it forms a tetramer. The enzyme was phosphorylated with [gamma-32P]ATP, and the pH stability profile of the phosphoenzyme indicated that two different amino acid residues were phosphorylated. Both a histidine residue and serine residues, including Ser-119 and Ser-121, appear to be phosphorylated. A Ser119Ala/Ser121Ala double mutant (i.e., with a Ser-to-Ala double mutation at positions 119 and 121), as well as Ser119Ala and Ser121Ala mutants, was isolated. All of these retained NDP kinase activity; also, both the Ser119Ala and Ser121Ala mutants could still be autophosphorylated. In the case of the double mutant, a slight autophosphorylation activity, which was resistant to acid treatment, was still detected, indicating that an additional minor autophosphorylation site besides His-117 exists. These results are discussed in light of the recent report of N. J. MacDonald et al. on the autophosphorylation of human NDP kinase (J. Biol. Chem. 268:25780-25789, 1993).
E2A-PBX1 is the oncogene produced at the t(1;19) chromosomal breakpoint of pediatric pre-B-cell leukemia. Expression of E2A-Pbx1 induces fibroblast transformation and myeloid and T-cell leukemia in mice and arrests differentiation of granulocyte macrophage colony-stimulating factor-dependent myeloblasts in cultured marrow. Recently, the Drosophila melanogaster protein Exd, which is highly related to Pbx1, was shown to bind DNA cooperatively with the Drosophila homeodomain proteins Ubx and Abd-A. Here, we demonstrate that the normal Pbx1 homeodomain protein, as well as its oncogenic derivative, E2A-Pbx1, binds the DNA sequence ATCAATCAA cooperatively with the murine Hox-A5, Hox-B7, Hox-B8, and Hox-C8 homeodomain proteins, which are themselves known oncoproteins, as well as with the Hox-D4 homeodomain protein. Cooperative binding to ATCAATCAA required the homeodomain-dependent DNA-binding activities of both Pbx1 and the Hox partner. In cotransfection assays, Hox-B8 suppressed transactivation by E2A-Pbx1. These results suggest that (i) Pbx1 may participate in the normal regulation of Hox target gene transcription in vivo and therein contribute to aspects of anterior-posterior patterning and structural development in vertebrates, (ii) that E2A-Pbx1 could abrogate normal differentiation by altering the transcriptional regulation of Hox target genes in conjunction with Hox proteins, and (iii) that the oncogenic mechanism of certain Hox proteins may require their physical interaction with Pbx1 as a cooperating, DNA-binding partner.
The aim of this prospective study was to determine factors influencing effects of inhaled nitric oxide (NO) on the pulmonary circulation and on gas exchange in critically ill patients with acute lung injury. Twenty-one hypoxemic patients with acute respiratory failure (PaO2 = 127 +/- 69 mm Hg during intermittent positive pressure ventilation, FiO2 = 1), were mechanically ventilated with 2 ppm NO and pure oxygen. The effect of positive end-expiratory pressure (PEEP) on alveolar recruitment was assessed on an anatomic basis using a high-resolution and spiral thoracic computed tomographic (CT) scan. Four conditions were studied in random order: zero end-expiratory pressure (ZEEP), ZEEP + 2 ppm NO, 10 cm H2O PEEP, 10 cm H2O PEEP + 2 ppm NO. During ZEEP and PEEP, NO significantly decreased pulmonary vascular resistance index (PVRI), mean pulmonary arterial pressure (MPAP), true pulmonary shunt (Qs/QT), and alveolar dead space (VDA/VT) and significantly increased PaO2 (p < 0.01). During ZEEP, NO-induced decreases in PVRI (delta PVRI) and MPAP (delta MPAP) were significantly correlated to baseline PVRI and MPAP (delta PVRI = -0.5 PVRI + 125, r = 0.97, p < 0.01 and delta MPAP = -0.28 MPAP + 4.8, r = 0.69, p < 0.05). These changes were not potentiated by PEEP-induced alveolar recruitment. The NO-induced increase in PaO2 (delta PaO2) was not significantly correlated with baseline PaO2 but was correlated with baseline PVRI (delta PaO2 = 0.11 PVRI + 30, r = 0.67, p < 0.05). In patients in whom PEEP was associated with alveolar recruitment, NO increased PaO2 by 66 +/- 24 mm Hg during ZEEP and by 104 +/- 26 mm Hg during PEEP (p < 0.01). In patients in whom PEEP did not induce alveolar recruitment, the NO-induced increase in PaO2 was similar during ZEEP and PEEP conditions (+70 +/- 15 mm Hg versus +76 +/- 12 mm Hg, NS). In patients with adult respiratory distress syndrome, factors determining NO-induced improvement in arterial oxygenation and pulmonary vascular effects are PEEP-induced alveolar recruitment and the baseline level of pulmonary vascular resistance.
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Mice of Kunming strain were infected with Schistosoma japonicum cercariae previously incubated with various concentrations of acridine mutagen ICR-170 for different time durations. At 6 weeks after infection, the mice were autopsied. The results showed that 24 out of 28(85.7%) adult female worms had deformed or lacked ovaries and vitelline glands when the cercariae were treated with the agent at a concentration of 10 micrograms/ml and incubated at 30.5 degrees C for 30min. No apparent changes were observed in the male worms inhabiting the mesenteric and portal veins with the females worms in their gynecophoral canals. The mutagenized female schistosomes obtained from the present experiment might be served as another form of attenuated worms for the induction of protective immunity.
In order to elucidate the relationship between N-, C-termini of TNF alpha and it's biological activity, a TNF alpha derivative 10 (TNF alpha D10) was prepared by changing amino acid at the N-terminus positions Ser(4), Ser(5), Asp(10) and C-terminus position Leu(157) to N-terminus Cys(4), Thr(5), Arg(10) and C-terminus Phe(157) with PCR site-directed mutagenesis. The results showed that the expression level of this mutein has not altered but its cytotoxic activity increased. This might result from trimer formation of TNF alpha D10 by changing N-terminal Ser(4) residue to Cys. HPLC showed that the molecular weight of TNF alpha D10 was 17kD, 35kD, 55kD respectively. In addition, we also found that the stability of TNF alpha D10 was less than that of TNF alpha when to be stored at -20 degrees C for two months. It might be caused by changing Leu(157) to Phe(157).