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Biomedical subjects

G Wu

Publications and source records attributed to G Wu.

At least 577 records · Page 32Linked to original sources
PubMed1992

Glutamine and glucose metabolism in bovine blood lymphocytes.

1. Glutamine and glucose metabolism was studied in bovine blood lymphocytes incubated at 37 degrees C in the presence of Krebs-Ringer bicarbonate buffer (pH 7.4) containing 1 mM [U-14C]glutamine and 5 mM [U-14C]glucose, respectively. 2. The major metabolic products from glutamine were ammonia, glutamate, and to a lesser extent, aspartate and CO2. Glucose was metabolized mainly to lactate and, to a lesser extent, pyruvate and CO2. These findings indicate incomplete oxidation of glutamine and glucose carbons in bovine blood lymphocytes. 3. Glucose provided three-fold greater amounts of energy to bovine blood lymphocytes than did glutamine on the basis of their measured end-products. Glycolysis accounted for 50% of glucose-derived ATP production. 4. Our findings suggest similar metabolic patterns of glutamine and glucose in lymphocytes between ruminants and non-ruminant species (e.g. rats). However, in contrast to rat peripheral lymphocytes, glucose, rather than glutamine, was a major energy substrate for bovine blood lymphocytes.

Adenosine Triphosphate↗
PubMed1992

Widely separated sequence elements within cucumber mosaic virus satellites contribute to their ability to induce lethal tomato necrosis.

To determine the structural requirements for cucumber mosaic virus (CMV) satellites to elicit lethal tomato necrosis, three satellite variants D, S and Y were used in the construction and cloning of chimeric cDNAs. D and S are necrogenic and non-necrogenic 'prototype' variants, respectively, and Y possesses the 3' conserved necrosis-determining region but does not cause lethal tomato necrosis. Its 5' half harbours an insertion/deletion region that results in a molecule about 30 nucleotides longer than other variants. Tomato bio-assays were conducted with RNA transcripts of all six chimeric combinations of the 5' and 3' halves of the three satellite variants divided by a common restriction site, as well as with a mutated chimera. None of the chimeras containing the 5' half of Y induced lethal necrosis in tomato even when their 3' halves were that of the D variant with the conserved necrogenic element. Chimeras with the 3' half of Y elicited only partial or restricted necrosis which was much less severe than that induced by prototype variant D, and often was not lethal. Site-directed mutation of a single nucleotide in proximity to the necrogenic element of such a chimera containing the 3' half of Y restored much lethal necrogenicity. The results revealed the presence of structural elements in CMV satellite variant Y that modulate or even suppress the expression of the 3' conserved necrosis-determining element. They indicate that in CMV satellites widely separated sequence elements constituting a three-dimensional requirement are responsible for eliciting lethal necrosis in tomato.

Base Sequence↗
PubMed1992

Isolation and characterization of Escherichia coli mutants affected in aerobic respiration: the cloning and nucleotide sequence of ubiG. Identification of an S-adenosylmethionine-binding motif in protein, RNA, and small-molecule methyltransferases.

We report the isolation and characterization of a mutant of Escherichia coli unable to grow aerobically on non-fermentable substrates, except for very slow growth on glycerol. The mutant contains cytochrome oxidases o and d, and grows anaerobically with alternative electron acceptors. Oxygen consumption rates of cell-free extracts were low relative to activities in an isogenic control strain, but were restored in vitro by adding ubiquinone-1 to cell-free extracts. Transformation with a cloned 2.8 kb ClaI-EcoRV fragment of chromosomal DNA restored the ability of this mutant (AN2571) to grow on succinate and also restored cellular quinone levels in this strain. The plasmid also complemented a previously isolated ubiG mutant (AN151) for aerobic growth on succinate. The nucleotide sequence revealed a 0.7 kb portion of gyrA. Unidirectional nested deletions from this fragment and complementation analysis identified an open reading frame encoding a protein with a predicted molecular mass of 26.5 kDa. This gene (ubiG) encodes the enzyme 2-octaprenyl-3-methyl-5-hydroxy-6-methoxy-1,4-benzoquinone methyltransferase, which catalyses the terminal step in the biosynthesis of ubiquinone. The open reading frame is preceded by a putative Shine-Dalgarno sequence and followed by three palindromic unit sequences. Comparison of the inferred amino acid sequence of UbiG with the sequence of other S-adenosylmethionine (AdoMet)-dependent methyltransferases reveals a highly conserved AdoMet-binding region. The cloned 2.8 kb fragment also contains a sequence encoding the C-terminus of a protein with 42-44% identity to fungal acetyl-CoA synthetases.

Aerobiosis↗
PubMed1992

Inhibition effects of KRDS, a peptide derived from lactotransferrin, on platelet function and arterial thrombus formation in dogs.

KRDS (Lys-Arg-Asp-Ser), a tetrapeptide from human lactotransferrin, was tested for its effects in vitro on dog platelet function and in vivo on femoral arterial thrombus formation in dogs. KRDS inhibited ADP (8 microM)-induced platelet aggregation (IC50: 350 microM) and arachidonic acid (2 mM)-induced thromboxane B2 generation (IC50: 175 microM). In addition, the thrombin (0.2 U/ml)-induced serotonin release was inhibited by KRDS (IC50: 525 microM) and the expression of alpha-granule membrane protein (GMP-140) was also inhibited (IC50: 350 microM). The results show that KRDS is an inhibitor for platelet aggregation and secretion to which the inhibition is more potent. Meanwhile, in the experiment of arterial thrombosis in dogs, KRDS (5 microM/kg) and 125I-SZ-51 (a monoclonal antibody against GMP-140) were injected before operation and immediately after the thrombus formation, respectively. In the KRDS group, the weight of removed thrombi was reduced to 50% of that in controls and the radioactivity per mg of labeled thrombi to 33.3% while in blood the radioactivity increased 2 times that in controls at the 4th hour after the injection of 125I-SZ-51. The radioactivity ratio between removed thrombi and blood was only 16% of that in controls. These results indicate that KRDS can inhibit thrombus formation in vivo and is a promising antithrombotic agent.

Amino Acid Sequence↗
PubMed1992

Interim report of Sino-Monica-Beijing for the years 1985-1989.

Interim results of Sino-Monica-Beijing for the 5 year period 1985-1989 are reported. The cardiovascular disease (CVD) risk factors increased between the surveys carried out in 1984-1985 and 1988-1989, especially blood cholesterol and body mass index.

Adult↗
PubMed1992

Purification and point-mutation analysis of human interleukin-2 (Ser-125).

A new type of IL-2(Ser-125) was purified by semi-preparative RP-HPLC, and its purity was analyzed with microbore HPLC, IEF, SDS-PAGE and capillary electrophoresis (CE). The N-terminal sequencing indicated the microheterogeneity of the N-terminus, i.e., N-Met(2/3) and N-Ala(1/3), which was identified with the results of CE and IEF. The amino acid sequence of the point mutated peptide confirmed the replacement of Cys-125 with Ser.

Amino Acid Sequence↗
PubMed1992

[Leptotrombidium scutellare in transmission of epidemic hemorrhagic fever virus].

To further elucidate the role of Leptotrombidium scutellare in transmission of epidemic hemorrhagic fever virus (EHFV), a series of studies were carried out from 1988 to 1990. EHFV was isolated from both larvae of free mites collected from the grassland of endemic areas and larvae of filial mites hatched in the laboratory. The suckling mice bitten by these larvae were infected by EHFV. Because only the larvae of chigger mite can bite vertebrate hosts and only take a full meal in its entire life cycle, the pathogen carried by it can only be originated from its parent mite via transovarial route. Thus it can be confirmed that the natural infection of EHFV in these mites is transferred via transovarial transmission. The results demonstrate that L (L.) scutellare can naturally be infected by EHFV; EHFV can be transmitted to the vertebrate host by biting of the larvae and can be transferred via transovarial transmission in mites; and therefore, L (L.) scutellare can serve as a transmitting vector of EHF.

Animals↗
PubMed1992

Detection of activated platelets using activation-dependent monoclonal antibody (SZ-51) in clinical disorders.

Platelets may become activated in a number of clinical disorders and participate in thrombus formation. A direct test for activated platelets in whole blood has been developed by radioimmunoassay with 125I labelled SZ-51, an antibody specific for an alpha-granule membrane protein (GMP-140) that associates with the platelet surface during secretion. The assay with sufficient sensitivity can be applied satisfactorily to detect as few as 2% activated platelets. In 50 normal subjects, minimal GMP-140 molecules per platelet were expressed on the surface of circulating platelets. The expression of GMP-140 molecules was increased transiently in 10 patients undergoing cardiopulmonary bypass, especially at the end of bypass. Evaluation of 18 patients with epidemic hemorrhagic fever (EHF) showed that the number of GMP-140 molecules on the platelet surface increased significantly, particularly at the shock phase, and closely related to the four different phases of EHF. In 9 patients suffered from acute myocardial infarction (AMI), the number of GMP-140 molecules changed with the procession of AMI and the highest occurred at the 48th h after AMI. The GMP-140 molecules were also increased in patients with asthma attack (n = 14), but not in patients with idiopathic thrombocytopenic purpura (n = 11). Considered together, these results suggest that activated platelets can be measured reliably in whole blood using radiolabeled SZ-51 antibody and the detection of activated platelets is potentially useful in identifying patients with certain thrombotic disorders.

Acute Disease↗
PubMed1992

[Experimental study of laser ablation on lethal arrhythmias--features and effectiveness of epicardial mapping].

To find the exact location of the ventricular arrhythmogenic myocardium, we mapped activation times of local epicardial electrograms (ATLE: 16 bipolar electrodes, 2 x 2 cm2) aided by an on-line computer and guided laser ablation of lethal ventricular arrhythmias induced by aconitine. Thirty-six tests involved 12 dog hearts. Nd:YAG laser application converted ventricular tachycardias and fibrillation to sinus rhythm in all tests. Epicardial mapping results showed: Taking ECG lead II as reference, the differences among all ATLE were within 15ms, and there was no obvious conduct slow zone before drugging and after resuming sinus rhythm, even though 298 +/- 157 mm2 photocoagulation areas (n = 36) resulted from laser irradiation; During VT, the majority of ATLE were preexcited from 90 to 30 ms, and more than one breakthrough point existed, with one predominating; ATLE changed significantly after laser. The ectopic foci were located exactly by using ATLE for laser treatment.

Aconitine↗
PubMed1992

Initiation of polymerization with ultrasound in dental composite resin.

A single paste composite resin comprising methacrylate monomers, inorganic fillers, activators and an ultrasonic generator assembled by a piezoceramic transducer and a working tip was developed. The resin can polymerize and harden under irradiation with ultrasound having frequencies from 20 to 50 KHz and intensity from 12 to 40 W/cm2. The new technology is promising as a safe and effective method for restoration of tooth defects.

Composite Resins↗
PubMed1991

Replication of cucumber mosaic virus satellite RNA in vitro by an RNA-dependent RNA polymerase from virus-infected tobacco.

An RNA-dependent RNA polymerase purified from tobacco infected with cucumber mosaic virus catalyzes the synthesis of (-) and (+) strands of the viral satellite RNA, CARNA 5, but fails to replicate the satellite RNA of peanut stunt virus (PSV). The enzyme replicates the genomic RNAs of the three principal cucumoviruses CMV, PSV and tomato aspermy virus (TAV) with varying efficiencies. The specificity with which CMV RdRp replicates different sequence-unrelated RNA templates suggests that the site of their recognition requires secondary or higher level structural organization.

Autoradiography↗
PubMed1991

Hereditary hemorrhagic macular dystrophy.

We treated two brothers who had a hemorrhagic macular lesion in one eye; a similar problem affected the fellow eye of both patients within eight months. Generalized fine granularity of the retinal pigment epithelium and peripheral iris transillumination defects were observed in both siblings. A study of the family suggested that the disorder was dominantly inherited and probably was Sorsby's pseudoinflammatory macular dystrophy. The macular lesions in one brother were treated by argon green laser photocoagulation and in the other brother by krypton red laser photocoagulation. Although the brother treated by krypton red laser photocoagulation attained better final visual function, additional differences in treatment methods also may have contributed to the final outcome.

Adult↗
PubMed1991

Combining position and acceleration measurements for joint force estimation.

The calculation of joint forces in biomechanics is usually based on the measurements of the kinematics of a given body segment, the estimation of the inertial properties of that segment and the solution of the 'inverse dynamics problem'. Such a process results in estimates of the joint forces and moments needed to sustain the monitored motion. This paper presents a new approach that combines position and acceleration measurements for the purpose of deriving high-quality joint force estimates. An experimental system that is based on an instrumented compound pendulum was designed and tested. The joint forces necessary to maintain a swinging motion of the pendulum were measured by an array of strain gauges, and were compared to the forces estimated by the integrated kinematic segment that measured the position and acceleration of the pendulum. The joint force measurements were also compared to the force estimates that were based on the calculated segmental acceleration generated by the differentiation of the segmental position alone. The results show a high degree of correlation between the forces estimated by the integrated segment and those measured by the strain gauges. The force estimates based on the position measurements alone were less accurate and noisier. The application of the integrated segment to the study of human kinetics is discussed and illustrated by the ankle and knee forces during slow walking. The results suggest that the use of accelerometers is necessary for the estimation of transients and high-frequency components of joint forces.

Acceleration↗
PubMed1991

The effect of ketone bodies on nitrogen metabolism in skeletal muscle.

1. The ketone bodies, D-beta-hydroxybutyrate and acetoacetate, inhibit glycolysis thereby reducing pyruvate availability which leads to a marked inhibition of branched-chain amino acid metabolism and alanine synthesis in skeletal muscles from fasted mammalian and avian species. 2. The rate of glutamine release from skeletal muscles from fasted birds is increased at the expense of alanine in the presence of elevated concentrations of ketone bodies because of an increase in the availability of glutamate for glutamine synthesis. 3. Ketone bodies inhibit both protein synthesis and protein degradation in skeletal muscles from fasted mammalian and avian species in vitro. The mechanisms involved remain unknown. 4. Inhibition of amino acid metabolism and protein turnover in skeletal muscle by ketone bodies may be an important survival mechanism during adaptation to catabolic states such as prolonged fasting.

Acetoacetates↗
PubMed1991

Deficiency of purine nucleoside phosphorylase activity in thymocytes from the immunodeficient diabetic BB rat.

The spontaneously diabetic BB (BBd) rat displays marked T lymphopenia. The present study was designed to investigate whether the immunodeficiency in this animal may be associated with deficiency of purine nucleoside phosphorylase (PNP) and possibly adenosine deaminase (ADA). The activities of these two enzymes were measured in lymphoid and non-lymphoid cells from both non-diabetes-prone (BBn) and BBd rats as well as from streptozotocin-induced diabetic (STZ) BBn rats. There were no significant differences between BBn and BBd rats in ADA activities in thymocytes, skeletal muscle or brain. However, ADA activity was increased (P less than 0.01) by 50% in BBd mesenteric lymph node lymphocytes and splenocytes as compared with BBn cells, but was not altered in cells from STZ-BBn rats. On the other hand, the PNP activity in BBd thymocytes was only 61% (P less than 0.01) of that observed in BBn cells. This PNP deficiency was not the consequence of diabetes per se, as its activity was normal in thymocytes from STZ-BBn rats. There were no significant differences in PNP activities between BBn and BBd rats in all other cell types examined. The diabetic BB rat may be a novel source of PNP-deficient thymocytes (mainly immature T cells) for studying biochemical mechanisms of immunodeficiency in association with decreased PNP activity. The findings also raise the question of whether a causal relationship exists between PNP deficiency and the recently demonstrated abnormality in T cell maturation in the thymus of the BBd rat.

Adenosine Deaminase↗
PubMed1991

Stimulation of neurite outgrowth in neuroblastoma cells by neuraminidase: putative role of GM1 ganglioside in differentiation.

Treatment of three neuroblastoma cell types in culture with neuraminidase resulted in enhanced neurite outgrowth. These included the mouse Neuro-2A and rat B104 and B50 lines. The morphological changes depended on the presence of exogenous Ca2+ and were accompanied by modest but statistically significant increases in 45Ca2+ influx. Neuraminidase-stimulated neuritogenesis was blocked by the B subunit of cholera toxin (cholera B) and anti-GM1 antibody, a finding suggesting the effect was due to an increased amount of GM1 on the cell surface. Cholera B also blocked the increase in 45Ca2+ influx. The mouse N1A-103 line, previously characterized as "neurite minus," did not respond to neuraminidase with either neurite outgrowth or enhanced Ca2+ influx. These results point to an influence of GM1 on neuritogenesis in cells with differentiation potential and suggest a mechanism involving modulation of Ca2+ flux.

Animals↗
PubMed1991

[Prenatal diagnosis of hemophilia A by DNA analysis].

Hemophilia A caused by defect in the gene of factor VIII is an inherited bleeding disorder most commonly seen in man. Prenatal diagnosis and carrier detection of hemophilia have been done through RFLP analysis in recent years. By use of Bc1I/FVIII-i18, XbaI/FVIII-i22, Bc1I/St14, TaqI/St14 and Bg1II/DX 13 RFLP analysis, prenatal diagnosis of 16 cases at risk of hemophilia A were performed. The results of gene diagnosis showed that two out of 16 pregnant women were normal and therefore prenatal diagnosis was not needed. Among the 14 fetuses at risk four normals and 4 carriers were found in the 8 female fetuses, while in the 6 male fetuses 3 were identified as normal and 3 affected.

Female↗