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Biomedical subjects

R Wu

Publications and source records attributed to R Wu.

At least 325 records · Page 18Linked to original sources
PubMed1992

Metabolism in and function of the central dopamine system after transplanting adrenal medullary tissue into the rat brain.

The unilateral nigrostriatal pathway of rats was destroyed by microinjecting 6-hydroxydopamine (6-OH-DA), and isogenous rat adrenal medullary tissue was then transplanted into the lesioned lateral caudate nucleus. After 2 months, rotational movement was almost abolished in 40% of the transplanted rats, and it was significantly reduced in the remaining 60%. Dopamine (DA) and its metabolites contents were significantly decreased in the lesioned side of the forebrain, while no changes of NA were found. After transplanting adrenal medullary tissue, the DA contents increased by 9% only, whereas the NA contents increased significantly. In addition, by examining synaptosomes in the brains of these rats, we found that on the lesioned side of nontransplanted rats, DA uptake and DA receptor binding were increased significantly, while no such changes were seen in the transplanted group.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1992

[Effects of electrical cauterization of nucleus raphe magnus on gastric acid output and serum gastrin level in rats].

Medullary raphe nucleus complex plays an important role in the regulation of visceral function. The effects of electrical damage of the nucleus raphe magnus on gastric acid output and serum gastrin level in anesthetized rats were observed. The experiments showed that damage of nucleus raphe magnus increased gastric acid output and serum gastrin level, which could be prevented by vagotomy but not by coeliac and superior mesenteric ganglionectomy.

Animals↗
PubMed1991

Mucin-like glycoprotein secreted by cultured hamster tracheal epithelial cells. Biochemical and immunological characterization.

We isolated mucin-like glycoproteins from the conditioned medium of primary hamster tracheal epithelial (HTE) cell culture and characterized them biochemically and immunologically. These glycoproteins were purified on Sepharose CL-4B after Streptomyces hyaluronidase treatment and then by CsCl-density-gradient centrifugation in the presence of 4 M-guanidinium chloride. The purified glycoproteins were resistant to digestion by chondroitin AC lyase, heparinase, heparitinase and endo-N-acetylglucosaminidases A, D and H, but susceptible to endo-beta-galactosidase and keratanase. SDS/PAGE demonstrated no contamination by low-molecular-mass proteins. The purified glycoproteins showed a peak buoyant density of 1.56 g/ml in CsCl-density-gradient centrifugation, and contained 10% peptide and 90% carbohydrate by weight. Carbohydrates in these glycoproteins contained N-acetylglucosamine, N-acetylgalactosamine, galactose, fucose, sialic acid and a trace amount of mannose, but no uronic acid. Serine and threonine together accounted for 27% of the total amino acid residues. In addition, the mucin-like glycoproteins exhibited blood-group A and B activities, and very strong inhibitory activity for influenza A virus haemagglutination. With the use of the purified glycoprotein as an antigen, six monoclonal antibodies that stained mucus granules in hamster tracheal epithelium were obtained. We characterized the antibody produced by one of the clones, HM D46. We conclude that HTE cells cultured in the serum-free medium secrete a glycoprotein with physicochemical properties similar to those known in various airways mucins.

Amino Acids↗
PubMed1991

Antigen presenting ability of thymic macrophages and epithelial cells: evidence for defects in the antigen processing function of thymic epithelial cells.

We compared the antigen presenting ability of cloned thymic macrophage and epithelial cell lines using T cell hybridomas with well-characterized activation requirements. A cloned thymic epithelial cell line (3D.1), preinduced with interferon-gamma (IFN-gamma) activated the T cell hybridoma 3DO-18.3 but not the T cell hybridoma DO-11.10. Analyses using preprocessed antigen suggest that the failure of 3D.1 to activate DO-11.10 is due to its inability to process chicken ovalbumin to produce a peptide recognized by the Ag:MHC T cell receptor of DO-11.10. The epithelial cell line 3D.1 was able to activate DO-11.10 if the superantigen staphylococcal enterotoxin B was used for activation instead of ovalbumin. These observations indicate that IFN-gamma-induced 3D.1 expresses sufficient I-Ad molecules to activate DO-11.10 but is unable to produce the peptide of ovalbumin recognized by DO-11.10. Furthermore, 3D.1 appears to be representative of nonmacrophage thymic stromal cells cultured in vitro, since heterogeneous cultures containing epithelial cells exhibited the same selective T cell activation characteristics. In contrast, thymic macrophage cell lines activated all T cells studied. These results suggest that there is a functional difference between the capacity of thymic epithelial cells and macrophages to process and present antigen to T cells.

Animals↗
PubMed1991

Endocrine function in children with human immunodeficiency virus infection.

We sought to determine if failure to thrive in pediatric patients with the human immunodeficiency virus could be explained based on endocrine dysfunction. Fourteen human immunodeficiency virus-infected pediatric patients, all of whom had adequate nutritional status, underwent endocrine evaluation. Growth hormone and cortisol responses to glucagon stimulation were adequate. Despite this, eight of the 12 subjects had low somatomedin C levels. Although all patients were clinically and biochemically euthyroid, 36% (5/14) demonstrated elevated baseline and peak thyrotropin levels in response to thyroid releasing hormone, suggesting a state of compensated hypothyroidism. Although the importance of these findings is unclear, it is possible that subtle alterations of thyroid regulation may contribute to failure to thrive in some pediatric patients infected with human immunodeficiency virus and may represent a potentially correctable defect.

Child↗
PubMed1991

Growth and differentiation of primary tracheal epithelial cells in culture: regulation by extracellular calcium.

Growth and differentiation of primary monkey tracheal epithelial (MTE) cells maintained on collagen gel substrata were studied in a defined serum-free culture medium containing 0.03 to 3.0 mM extracellular calcium. Cell attachment efficiency (40-60%) was not altered by different calcium levels. Growth of primary MTE cells on collagen gel substrata, which was vitamin A dependent, was enhanced 50% in the medium supplemented with high calcium (greater than 0.3 mM). High calcium medium also increased cell-cell interactions, formation of desmosomes, and multi-cell layering. The relative content of mucous cells, which were identified by a mucin-specific monoclonal antibody and the presence of mucus-secreting granules at the ultrastructural level, was greater in the high-calcium medium. Furthermore, the secretion of mucin into the medium, determined either by an ELISA or by the incorporation of 3H-glucosamine into mucous glycoprotein fractions, was also increased more than 5-fold in media containing high calcium content (greater than 0.6 mM). In contrast, MTE cells cultured in low calcium medium (less than 0.15 mM) were squamous-like with prominent tonofilaments, and their secretory product was mainly hyaluronate. These results demonstrate that media containing a high calcium content promote conducting airway epithelium to express mucous cell differentiation, while media with low calcium content promote squamous cell differentiation.

Animals↗
PubMed1991

A novel glycine-rich cell wall protein gene in rice.

A genomic clone isolated from rice (Oryza sativa var. IR 36) contains a gene that encodes a glycine-rich cell wall protein. This gene is a member of a multi-gene family. Two transcripts with different 5' termini are encoded by this gene and the expression of these two transcripts is differentially regulated. The amino acid sequence derived from the DNA sequence of this gene has a putative amino terminal signal peptide, and a highly repetitive structure in the putative mature protein. A model is proposed which describes the potential monomeric structure of this glycine-rich protein and how these monomers may be covalently linked to produce a network-like structure.

Amino Acid Sequence↗
PubMed1991

Construction of expression vectors based on the rice actin 1 (Act1) 5' region for use in monocot transformation.

It has been previously reported that the 5' region of the rice actin 1 gene (Act1) promoted high-level expression of a beta-glucuronidase reporter gene (Gus) in transformed rice cells. In this paper we describe the construction of Act1-based expression vectors for use in monocot transformation. As part of the development of these vectors, we have evaluated the influence of the Act1 first intron, the Act1-Gus junction-encoded N-terminal amino acids, and the sequence context surrounding the Act1 and Gus translation initiation site on Act1-Gus gene expression in rice and maize cells. We have found that addition of Act1 intron 1 to the transcription unit of a Gus reporter gene under control of the cauliflower mosaic virus (CaMV) 35S promoter stimulated GUS activity more than 10-fold in transformed rice cells. Optimization of the sequence context around the Gus translation initiation site resulted in a 4-fold stimulation of Gus expression in transformed rice cells. By utilizing both the Act1 intron 1 and optimized Gus translation initiation site, a 40-fold stimulation in Gus expression from the CaMV 35S promoter has been achieved in transformed rice cells; very similar results were obtained in transformed maize cells. Taken together these results suggest that the Act1-based expression vectors described here should promote the expression of foreign genes in most, if not all, transformed monocot cells to levels that have not previously been attainable with alternative expression vectors.

Actins↗
PubMed1991

Localization of specific repetitive DNA sequences in individual rice chromosomes.

This paper describes the characterization and chromosomal distribution of three different rice (Oryza sativa) repetitive DNA sequences. The three sequences were characterized by sequence analysis, which gave 355, 498 and 756 bp for the length of the repeat unit in Os48, OsG3-498 and OsG5-756, respectively. Copy number determination by quantitative DNA slot-blot hybridization analysis showed 4000, 1080 and 920 copies, respectively, per haploid rice genome for the three sequences. In situ DNA hybridization analysis revealed that 95% of the silver grains detected with the Os48 probe were localized to euchromatic ends of seven long arms and one short arm out of the 12 rice chromosomes. For the OsG3-498 repetitive sequence, the majority of silver grains (58%) were also clustered at the same chromosomal ends as that of Os48. The minority (28%) of silver grains were located at heterochromatic short arms and centromeric regions. For the OsG5-756 repetitive sequence, 81% of the silver grains labeled the heterochromatic short arms and regions flanking all of the 12 centromeres. Thus, each of these three repetitive sequences was distributed at specific defined chromosomal locations rather than randomly at many chromosomal locations. The approximate copy number of a given repetitive DNA sequence at any specific chromosomal location was calculated by combining the information from in situ DNA hybridization analysis and the total copy number as determined by DNA slot-blot hybridization.

Base Sequence↗
PubMed1991

Structure and molecular evolutionary analysis of a plant cytochrome c gene: surprising implications for Arabidopsis thaliana.

We have isolated a cytochrome c gene from Arabidopsis thaliana (cv. Columbia), which is the first cytochrome c gene to be cloned from a higher plant. Genomic DNA blot analysis indicates that there is only one copy of cytochrome c in Arabidopsis. The gene consists of three exons separated by two introns. Gene features such as regulatory regions, codon usage, and conserved splicing-specific sequences are all present and typical of dicotyledonous plant nuclear genes. We have constructed phenograms and cladograms for cytochrome c amino acid sequences and histone H3, alcohol dehydrogenase, and actin DNA sequences. For both cytochrome c and histone H3, Arabidopsis clusters poorly with other higher plants. Instead, it clusters with Neurospora and/or the yeasts. We suggest that perhaps this observation should be considered when using Arabidopsis as a model system for higher plants.

Actins↗
PubMed1991

Isolation and molecular evolutionary analysis of a cytochrome c gene from Oryza sativa (rice)

A cytochrome c gene, OsCc-1, from rice (Oryza sativa) has been isolated and analyzed. The OsCc-1 gene encodes a cytochrome c protein that is typical of higher-plant cytochrome c proteins. OsCc-1 consists of three exons separated by two introns that are 817 and 747 bp in length, respectively. From genomic DNA hybridization analysis, OsCc-1 appears to be one of possibly two cytochrome c genes in several Asian, American, and Indian rice species and varieties surveyed. A single, unique cytochrome c gene appears to be present in one African cultivated rice species. We performed comparative molecular evolutionary analyses of OsCc-1 and other cytochrome c genes. We calculated a unit evolutionary period of 19.4 Myr for cytochrome c DNA sequences, which agrees closely with previous estimates based on protein sequence comparisons.

Amino Acid Sequence↗
PubMed1991

Analysis of rice Act1 5' region activity in transgenic rice plants.

The 5' region of the rice actin 1 gene (Act1) has been developed as an efficient regulator of foreign gene expression in transgenic rice plants. To determine the pattern and level of rice Act1 5' region activity, transgenic rice plants containing the Act1 5' region fused to a bacterial beta-glucuronidase (Gus) coding sequence were generated. Two independent clonal lines of transgenic rice plants were analyzed in detail. Quantitative analysis showed that tissue from these transgenic rice plants have a level of GUS protein that represents as much as 3% of total soluble protein. We were able to demonstrate that Act1-Gus gene expression is constitutive throughout the sporophytic and gametophytic tissues of these transgenic rice plants. Plants from one transgenic line were analyzed for the segregation of GUS activity in pollen by in situ histochemical staining, and the inheritance and stability of Act1-Gus expression were assayed in subsequently derived progeny plants.

Actins↗
PubMed1991

The effect of long-acting analog of luteinizing hormone-releasing hormone on growth hormone secretory dynamics in children with precocious puberty.

Long-acting preparations of LHRH (LHRHa), such as leuprolide acetate, have been shown to selectively and reversibly suppress the clinical and biochemical features of central precocious puberty (CPP). The withdrawal of gonadal sex steroids results in a decline of growth velocity and a decrease in the rate of bone age maturation, with resultant improvement in predicted adult stature. The purpose of this study was to define GH secretory dynamics in children treated with leuprolide acetate. Twelve-hour nocturnal GH studies were performed in five children (four girls and one boy) with CPP before and after 6 months of treatment with leuprolide acetate. Mean GH levels, GH secretory rate, and number of GH secretory episodes were determined. Secretory profiles were analyzed using the Cluster program. Growth velocity, somatomedin-C, and dehydroepiandrosterone sulfate were measured before and after 6 months of therapy. By 6 months of therapy, there was a significant decrease in mean growth velocity from 10.5 +/- 3.3 to 6.7 +/- 1.6 cm/yr. Somatomedin-C levels remained the same at 46.90 +/- 9.51 and 52.5 +/- 12.40 nmol/L. Levels of dehydroepiandrosterone sulfate remained unchanged at 118.6 +/- 71.4 and 139.0 +/- 61.3 mumol/L at 0 and 6 months of the study. By 6 months, there was a significant decrease in mean GH levels from 13.6 +/- 5.3 to 6.4 +/- 3.4 micrograms/L (P less than 0.05). Total GH levels decreased from 1367.9 +/- 687.3 to 447.0 +/- 186.5 ng/12 h. The number of GH secretory episodes remained the same at 5.4 +/- 1.5 and 4.8 +/- 1.0/12 h at 0 and 6 months of study. Therefore, the decrease in GH that occurs during the withdrawal of gonadal sex steroids with LHRHa in children with CPP is an amplitude-modulated phenomenon, as the number of secretory peaks remains unchanged.

Antineoplastic Agents↗
PubMed1991

Treatment of essential hypertension with auriculoacupressure.

Auriculoacupressure was used in the treatment of 291 cases of essential hypertension, in comparison with 51 similar cases treated with Fufang Jiangya (composite hypotensive) Tablets. Analysis of results showed that the therapeutic effects in the 2 groups were similar, while the rate of marked efficacy in the acupressure group was higher than that of the medication group, and the level of blood lipids also significantly dropped (P less than 0.01); there was only minor improvement in blood rheology. In addition, acupressure manifested biphasic regulatory effects on sinus arrythmia. The curative effect of acupressure on essential vascular hypertension was good.

Acupuncture Points↗
PubMed1990

Multiple protein factors bind to a rice glutelin promoter region.

Our goal is to identify cis-acting elements in the regulatory region of the major seed storage protein gene in rice. A glutelin gene (pGL5-1) has been cloned by screening a rice genomic DNA library with synthetic oligonucleotides and with an amplified DNA fragment. A transient expression assay using immature rice seeds shows that its 5' flanking sequence can direct the synthesis of beta-glucuronidase (GUS) when fused upstream of the GUS coding region. Gel-retardation assays were performed to study protein-DNA interactions between putative regulatory sequences of pGL5-1 and nuclear proteins from immature rice seeds. We demonstrate that at least six protein-DNA complexes are formed between the 5' flanking sequence of pGL5-1 (-677 to -45) and nuclear protein factors. By subsequent DNase I-footprinting analyses we defined several protein-binding regions. Two of the protein-binding sequences contain the TGAGTCA motif, which is also present in the -300 element found in the 5' flanking sequences of several storage protein genes of other crop plants, and to which the transcription factors jun and GCN4 bind.

Base Sequence↗
PubMed1990

Resistance to receptor-mediated degradation of a murine epidermal growth factor analogue (EGF-Val-47) potentiates its mitogenic activity.

In most cell types two classes of epidermal growth factor (EGF) receptors can be found: a major class that binds EGF with relatively low affinity and a minor class that binds with very high affinity. Structure-function studies have shown that mutations at amino acid 47 in the EGF molecule severely reduce its affinity for the EGF receptor but do not cause preferential binding to one or the other subclass of receptors. Using three EGF derivatives with a mutation at amino acid 47 (Ser-47, Leu-37-Tyr-47, and Val-47), we have investigated the relative contribution of the two receptor subclasses to the EGF-dependent mitogenic response. We show that mitogenicity correlates exclusively with occupancy of the high-affinity receptor and that full occupancy of this subclass is required for maximal stimulation. In addition we demonstrate that for the EGF-Val-47 analogue this requirement can be abrogated and half-maximal biological activity reached with a high-affinity receptor occupancy of only 8%. While the rate of internalization did not significantly differ between EGF-Val-47 and native mEGF, the analogue was much more resistant to degradation by cellular proteases and, after binding and receptor-mediated internalization, was released into the medium predominantly in an intact form. We propose that the increased mitogenicity of EGF-Val-47 is due to its prolonged half-life, resulting in continued occupancy of the high-affinity EGF receptor.

Animals↗