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X J Guo

Publications and source records attributed to X J Guo.

At least 37 records · Page 2Linked to original sources
PubMed1994

[Effects of pentoxifylline on leukocyte in the lungs of dog with fat tissue extract-induced respiratory distress syndrome].

We studied the effects of pentoxifylline (PTX) on the polymorphonuclears (PMN) and alveolar macrophages (AM) in the lung of dog with fat tissue extract induced respiratory distress syndrome (RDS). Results showed that PTX decreased PMN accumulation and infiltration in the lung; the total leukocytes in BALF dropped from 2.92 x 10(8) in the experimental group to 1.21 x 10(8) in the PTX-treated group (P < 0.001); the percentage of PMN also reduced from 35.4% to 14.3% (P < 0.01); the production of IL-1 and TNF by AM in the PTX-treated group was markedly inhibited as compared with the experimental group (P < 0.001, P < 0.05). We conclude that PTX has an inhibitory effect on PMN and AM in the lung of dog with RDS, and PTX may have potential therapeutic effect on ARDS.

Animals↗
PubMed1994

[Effect of pentoxifylline on respiratory distress syndrome in dogs].

We examined effects of early post-treatment with pentoxifylline (PTX) on fat tissue extract (FTE) induced respiratory distress syndrome in dogs. The results indicate that the arterial oxygen tension in the animals received PTX dropped more slowly, the total leukocytes and albumin in BALF were obviously reduced, the increased production of IL-1 and TNF by alveolar macrophages was partly inhibited, other parameters such as W/D ratio were also markedly decreased when compared to the animals received FTE only. PTX decreases neutrophil accumulation and prevents the increase in pulmonary vascular permeability, and attenuates edema formation in FTE-induced lung injury. The mechanism may relate with the effect of PTX inhibiting inflammatory leukocytes and protecting the pulmonary vascular endothelial cells.

Adipose Tissue↗
PubMed1993

Comparison of barley malt alpha-amylase isozymes 1 and 2: construction of cDNA hybrids by in vivo recombination and their expression in yeast.

Germinating barley produces two alpha-amylase isozymes, AMY1 and AMY2, having 80% amino acid (aa) sequence identity and differing with respect to a number of functional properties. Recombinant AMY1 (re-AMY1) and AMY2 (re-AMY2) are produced in yeast, but whereas all re-AMY1 is secreted, re-AMY2 accumulates within the cell and only traces are secreted. Expression of AMY1::AMY2 hybrid cDNAs may provide a means of understanding the difference in secretion efficiency between the two isozymes. Here, the efficient homologous recombination system of the yeast, Saccharomyces cerevisiae, was used to generate hybrids of barley AMY with the N-terminal portion derived from AMY1, including the signal peptide (SP), and the C-terminal portion from AMY2. Hybrid cDNAs were thus generated that encode either the SP alone, or the SP followed by the N-terminal 21, 26, 53, 67 or 90 aa from AMY1 and the complementary C-terminal sequences from AMY2. Larger amounts of re-AMY are secreted by hybrids containing, in addition to the SP, 53 or more aa of AMY1. In contrast, only traces of re-AMY are secreted for hybrids having 26 or fewer aa of AMY1. In this case, re-AMY hybrid accumulates intracellularly. Transformants secreting hybrid enzymes also accumulated some re-AMY within the cell. The AMY1 SP, therefore, does not ensure re-AMY2 secretion and a certain portion of the N-terminal sequence of AMY1 is required for secretion of a re-AMY1::AMY2 hybrid.

Amino Acid Sequence↗
PubMed1992

[On the correction of systematic errors of analytical methods used in the content uniformity test].

In this paper, the constant and proportional systematic errors of analytical methods for the content uniformity test were studied with reference to the accurate analytical method for the assay. Seven monographs of tablets admitted to USP(XXII), Ch P (1985, 1990) and JP(XI) were taken as cases in point and the systematic errors of two of them, i.e. digoxin and nitroglycerin tablets, were ascertained by the test of significance. To improve the accuracy of analytical methods for the content uniformity test, a correction formula more reasonable and convincing than that of USP (XXI, XXII) was proposed, and its theoretical basis described briefly.

Chemistry Techniques, Analytical↗
PubMed1991

The murine heat-stable antigen: a differentiation antigen expressed in both the hematolymphoid and neural cell lineages.

The murine heat-stable antigen (HSA) and the p31 antigen are cell surface glycoconjugates which are transiently expressed during the development and differentiation of the hematolymphoid and neural cell lineages, respectively. We show here that monoclonal antibodies which react with these two species recognize a common antigenic determinant which is expressed on both HSA and p31, and the HSA and p31 share a common protein core. Differences in the molecular weights of the antigens most likely reflect variations in the extent of post-translational modifications. From these studies we conclude that these antigens are members of the same family of heat-stable antigens. Our results lead us to speculate on how these molecules are related, their function, and what role they play in cellular differentiation in hematolymphoid and neural cell development.

Animals↗
PubMed1991

Removal of C6 astrocytoma cell surface molecules with phosphatidylinositol phospholipase C: effect on regulation of neural cell adhesion molecule isoforms.

Different membrane-associated isoforms of the neural cell adhesion molecules have been described. One of them, N-CAM120, has been shown to be anchored to the membranes by a complex glycan-phosphatidylinositol group and to be releasable, under soluble form, by the bacterial enzyme phosphatidylinositol-phospholipase C. We used the C6 rat astrocytoma cell line expressing both N-CAM120 and the transmembrane isoform N-CAM140 as a model system. We investigated whether artificial depletion of cell membrane N-CAM120 influences the synthesis and the messenger RNA transcript levels of the isoforms of the neural cell adhesion molecules. Our results showed an increase in the rate of N-CAM120 protein synthesis, whereas the expression of N-CAM140 decreased. Additionally, perturbations in the levels of the 6.7-kb messenger RNA encoding for N-CAM140 were observed, whereas the 2.7-kb transcript encoding for N-CAM120 remained stable. Examination of the time course for the reexpression of N-CAM120 showed that control levels were recovered after 24 h. We provide evidence that N-CAM120 spontaneously released in the culture medium is not incorporated into the extracellular matrix; however, its concentration is important because, if the medium was changed, cells rapidly released a new pool.

Animals↗
PubMed1991

[Activation of neutrophils in allergic asthmatics].

Neutrophil chemotactic activity (NCA) and activity of myeloperoxidase (MPO) of the neutrophils in asthmatic patients during attacks and in remission and normal controls were determined. The results showed that NCA and activity of MPO in asthmatic patients during attacks were significantly higher than those in remission and in the controls. There was no difference of either NCA or the activity of MPO between asthmatic patients in remission and the controls. There was definite correlation between NCA and activity of MPO in asthmatic patients during attacks, but no correlation between the asthmatic patients in remission and the controls. The results suggest that chemotaxis and activation of neutrophils by neutrophil chemotactic factor may play an important role in pathophysiology of asthma.

Adolescent↗
PubMed1990

The respiration of cells and mitochondria of porin deficient yeast mutants is coupled.

Several mutants of yeast lacking the porin gene have been found stable and viable on glucose or glycerol media. Ethanol-supported respiration of porin-free mutant and wild cells appeared equally coupled in vivo being similarly depressed by inhibitors of ADP/ATP translocase or of ATP synthase and stimulated by the uncoupler FCCP. The absence of porin in isolated mutant mitochondria hardly impaired the electron flux but increased the requirement for Mg2+ (or Ca2+) and for ADP and carboxyatractylate concentrations necessary to drive effectively state 3 - state 4 and state 4 - state 3 transitions, respectively. The existence of another porin species, possibly controlled by bivalent cations, is postulated.

Adenosine Diphosphate↗
PubMed1990

Evaluation of the effect of suramin on neural cell growth and N-CAM expression.

Suramin, a polysulfonated naphthylurea, is currently under investigation for treatment of advanced malignancy and has been shown to exhibit antiproliferative effects on some cells. We investigated its action on two cell lines of neural origin, one with neuronal (N2A) and the other with glial (C6) phenotype, as well as on brain primary cultures. We showed that suramin completely inhibited astrocytoma proliferation for an optimal dose of 1000 micrograms/ml but had the opposite effect on neuroblastoma cells. For these cells, doses as low as 12.5 micrograms/ml first increased cell proliferation and then led to massive cell death. This cytotoxic effect, which could be compatible with an internalization of the drug by the cells, was also observed for postmitotic neurons in brain primary cultures. In both cell lines, suramin was responsible for an accumulation of the neural cell adhesion molecule at the cell surface. One of the causes was the inhibition by suramin on the liberation processes of the phosphatidylinositol anchored Mr 120,000 isoform. At the mRNA level, suramin (12.5 to 50 micrograms/ml) induced an increase of all neural cell adhesion molecule transcripts in N2A but not in C6 cells. Suramin did not have an overall effect on transcription rates or RNA stability as the levels of transcripts coding for PrPc, another cell surface molecule, and actin were not affected. Our data demonstrated pleiotropic action of suramin. The neurotoxic effect exerted on neurons needs to be considered as possible outcomes for the use of suramin in humans.

Animals↗
PubMed1990

Suramin inhibits proliferation of rat glioma cells and alters N-CAM cell surface expression.

Suramin, a drug used in the treatment of trypanosomiasis and onchocerciasis inhibits growth-factor-induced mitogenesis. We have investigated the effect of suramin on the growth rate and the morphology of C6 glioma cells cultured in the presence of serum or in a serum-free defined medium. Exponentially growing cells were seeded in multi-dish plates (5 x 10(4) cells/2 cm2 well) in DMEM supplemented with 5% fetal calf serum and were continuously exposed to 1 microgram/ml to 1,000 micrograms/ml suramin. Growth rate (determined 9 days after seeding) was reduced by 5%, 33%, 56% and 97%, respectively for suramin concentrations of 1, 10, 100 and 1000 micrograms/ml. Similar results were obtained in serum-free defined medium (DMEM/F12, 1:1, v:v, EGF 5 ng/ml, transferrin 5 micrograms/ml, selenium 10 ng/ml). Moreover, the concentration of suramin in the culture medium remained constant, demonstrating that the drug was not actively metabolized by the cells. Suramin also induced marked changes in cell morphology: the usual bipolar shape of C6 cells evolved toward a more differentiated appearance, with numerous cellular processes allowing a wide number of cell-cell contacts. In parallel, we monitored expression of an adhesion molecule (N-CAM) at both the mRNA and protein levels. Indirect immunofluoresence technique showed an important increase in cell surface N-CAM expression, starting from a dose of 10 micrograms/ml suramin, whereas total cellular content of N-CAM protein as well as its mRNA levels were unaffected. We also observed that the levels of expression of actin and N-CAM mRNAs decreased by a factor of two in cells maintained in defined medium. However, the relative ratio of N-CAM mRNA over actin mRNA was virtually unchanged following suramin treatment. Taken together, our results suggest that suramin (i) exerts a blocking effect of autocrine growth factors, (ii) interferes with the turn-over mechanisms of N-CAM expressed at the cell surface, either by impairing its endocytosis and/or the process of release of the N-CAM 120 isoform.

Actins↗
PubMed1990

Identification of a serum-inducible messenger RNA (5B10) as the mouse homologue of calcyclin: tissue distribution and expression in metastatic, ras-transformed NIH 3T3 cells.

A mouse mRNA, provisionally designated 5B10, has been cloned based on its inducibility by serum in quiescent murine fibroblasts. Here we report the full-length complementary DNA sequence and a partial characterization. There are about five copies of the gene in the mouse genome. Sequence analysis of the 5B10 coding region reveals 94 and 97% amino acid identity to human and rat calcyclin, respectively. Although the coding region has been highly conserved during evolution of the rodent and human genomes, the untranslated flanking sequences differ significantly. A protein of Mr about 8000 was produced by in vitro translation of the mRNA transcribed in vitro from 5B10 complementary DNA in a riboprobe vector. An antiserum raised against a portion of the predicted human calcyclin protein cross-reacted with this mouse protein. 5B10 mRNA was found in greatest amount in organs containing proliferating cells, e.g., epidermis, skin, stomach, uterus of pregnant mouse, placenta, and decidua. Brain, liver, mature thymus, and skeletal muscle had little or no detectable 5B10 mRNA. 5B10 mRNA levels were higher in cells treated with 7,12-dimethylbenzanthracene and 12-O-tetradecanoylphorbol-13-acetate than in their normal counterparts, suggesting a role in tumorigenesis. In addition, high 5B10 mRNA levels were associated with metastatic ability in a series of ras-transformed cells, in proportion to levels of ras p21 expressed by the cells, implicating 5B10 even more deeply in carcinogenesis.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1989

[Experimental research on the pathogenic mechanisms in adult respiratory distress syndrome].

In order to study the pathogenic mechanisms of adult respiratory distress syndrome (ARDS), the neutrophil aggregation activity, platelet aggregation rate and levels of thromboxane, prostacyclin, superoxide dismutase, lipoperoxides, neutrophil elastase, alpha 1-antitrypsin and angiotensin conversion enzyme were measured in 84 experimental dogs. Under the action of activated complement C5a, polymorphonuclear leukocyte aggregation with increased release of oxygen radicals play an important role in the pathogenesis of ARDS.

Animals↗
PubMed1988

Yeast gene SRP1 (serine-rich protein). Intragenic repeat structure and identification of a family of SRP1-related DNA sequences.

We have isolated and sequenced a yeast gene encoding a protein (Mr 24,875) very rich in serine (SRP) and alanine residues that accounted for 25% and 20% of the total amino acids, respectively. The SRP1 gene is highly expressed in culture conditions leading to glucose repression (Marguet & Lauquin, 1986), the amount of SRP1 mRNA representing about 1 to 2% of total poly(A)+ RNA. A repetitive structure of eight direct tandem repeats 36-base long, also reflected in the amino acid sequence, was found in the second half of the open reading frame. The consensus amino acid sequence of the repeat was Ser-Ser-Ser-Ala-Ala-Pro-Ser-Ser-Ser-Glu-Ala-Lys. Replacing the genomic copy of the cloned gene with a disrupted SRP1 gene indicated that the SRP1 gene was not essential for viability in yeast, but several SRP1-homologous sequences were found within the yeast genome, raising the possibility that the disrupted SRP1 gene is rescued by one of the other SRP-homologous sequences. Complete separation of yeast chromosomes by contour-clamped homogeneous field electrophoresis indicated that, apart from chromosome V, which carries the SRP1 gene, 12 chromosomes have SRP-related sequences with various degrees of homology. These sequences were located on chromosomes XV, VII and XI under stringent conditions of hybridization (tm -20 degrees C), and observed on chromosomes I, II, III, IV, VI, VIII, X, XI and XII, only under low-stringency conditions (tm -40 degrees C). Northern blot analysis of both the wild type and SRP1-disrupted strains indicated that along with SRP1 at least one more member of the SRP family was transcribed to a 0.7 kb (1 kb = 10(3) bases) polyadenylated RNA species clearly distinct from the SRP1-specific mRNA (1 kb long). Analyses of the SRP1 repeat domain suggested a model for the divergent evolution of the repeats in the SRP1 sequence.

Amino Acid Sequence↗