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Biomedical subjects

Z Hu

Publications and source records attributed to Z Hu.

At least 235 records · Page 13Linked to original sources
PubMed1998

[Determination of 6 isoflavonoids in the hairy root cultures of Astragalus membranaceus by HPLC].

An accurate RP-HPLC method for the determination of 10-hydroxy-3, 9-dimethoxypeterocarpan, (3R) 8,2'-dihydroxy-7,4'-dimethoxyisoflavan, formonenetin (7-hydroxy-4'-methoxyisoflavone), 8, 3'-dihydroxy-7, 4'-dimethoxy-isoflavone, 2'-hydroxy-3', 4'-dimethoxyisoflavan-7-O-glucopyranoside and alycosin (7,3'-dihydroxy-4'-methoxyisoflavone) in the hairy root cultures of Astragalus membranaceus was developed. Among them, 10-hydroxy-3, 9-dimethoxypeterocarpan, (3R) 8,2'-dihydroxy-7,4'-dimethoxyisoflavan and 8,3'-dihydroxy-7,4'-dimethoxyisoflavone were new compounds in Astragalus membranaceus. The analytical column was Nucleosil C18. The mobile phases were methanol-water = 3:2 and 1:1 (v/v). The detection wavelengths were 254 nm and 280 nm. Calibration graphs were rectilinear between 2.5 micrograms and 12.5 micrograms. The recoveries were between 96.47% and 103.33%. The relative standard deviations (RSDs) of measurement precision test were 2.57%-6.52%. The flavonoid contents in the hairy root cultures were between 0.0005% and 0.0065% (dry weight).

Astragalus propinquus↗
PubMed1998

[A comparative study on the syntheses of DNA, RNA and protein during in vitro organogenesis and somatic embryogenesis of Lycium barbarum L].

After the calli originating from the leaf explant of Lycium barbarum L. were selected and proliferated, the yellowish calli with same origin, similar state were transferred to O medium or E medium and the regenerative systems of organogenesis and somatic embryogenesis might form. By these systems, a comparative study on the synthetic activities of DNA, RNA and protein in the two in vitro regeneration pathways was carried out. The results were as follows: (1) Before meristemoid and embryogenic cells were formed, the synthesis of RNA was activated firstly, followed with the increase of synthesis rates of DNA and protein. During the formation of globular embryo, the synthesis rate of DNA increased quickly and then the activities of syntheses of RNA and protein reached the peak, while it was the contrary during germination of adventitious bud. (2) Components of soluble protein changed regularly. A peptide (153.6 kD) appeared during the initiation of both organogenesis and somatic embryogenesis. Several peptides disappearing gradually in the early-stage of differentiation could regenerate with the formation of shoot primordium and globular embryo. Corresponding to morphogenesis, both regenerative systems had specific peptides (84.9 kD, 46.3 kD and 44 kD, 36.2 kD) as molecular markers of its own development. In addition, the relation and mechanism of the two regenerative systems were discussed.

Culture Techniques↗
PubMed1998

[Transient response in electric measurement of human auricular point].

This is an experiment on the measuring E approximately t and R approximately t for human auricular point, which shows there is a transient response of electric potential E(t) and voltage drop U(t) when t < 2 tau and there is at intervals change with the time after 2 tau about R(t) and E(t). We have obtained a response function of the E(t) and U(t) by the circuit analysis. The parameter of the transient character is relaxation time tau, tau approximately RC. The mathematical model is in correspondence with the experimental result of the auricular point and TPM simulation. It indicates that the character changing with the time should be extracted after 2 tau. This experiment is of importance to understanding the electric character of the otopoint.

Acupuncture Points↗
PubMed1998

[Transient response in electric measurement of human auricular point].

This is an experiment on the measuring E-t and R-t for human auricular point, which shows there is a transient response of electric potential E(t) and voltage drop U(t) when t < 2 tau and there is at intervals change with the time after 2 tau about R(t) and E(t). We have obtained a response function of the E(t) and U(t) by the circuit analysis. The parameter of the transient character is relaxation time tau,tau approximately RC. The mathematical model is in correspondence with the experimental result of the auricular point and TPM simulation. It indicates that the character changing with the time should be extracted after 2 tau. This experiment is of importance to understanding the electric character of the otopoint.

Acupuncture Points↗
PubMed1998

[Effects of hairy root huangqi on hemopoietic function].

The effects of hairy root Huangqi on hemopoietic system were studied in this paper. The oral administration of 5-20 g/kg hairy root Huangqi per day for 5-12 days could increase the count of RBC and reticulocytes in mice with hemorrhagic anemia, raise the hemoglobin, RBC and hematocrit in mice with hemolytic anemia, enhance the number of WBC and nucleared cells in bone marrow of mice treated with cyclophosphamidum or x-rays. The experiments showed that hairy root Huangqi promoted the hemopoietic function. The effects were similer to those of natural Huangqi.

Anemia, Hemolytic↗
PubMed1998

Unilateral acute idiopathic maculopathy.

PURPOSE: To discuss the fluorescein angiographic features and diagnosis as well as differential diagnosis. METHODS: In our hospital, we have found three cases of UAIM, one of them has eccentric maculopathy, another has papillitis, and the third associates with pregnancy. Each has characteristic clinical findings. We have made the diagnosis base on ophthalmoscopy and fluorescein angiography (FA). RESULTS: Three patients with UAIM have been experienced sudden unilateral decreased visual acuity. The significant changes on fundus are retinal pigment epithelium (RPE) thickening with neurosensory retinal detachment with in the macular area. FA showed early patchy hypofluorescence and hyperfluorescence at the level of the RPE. 'Bull's eye appearance may occur in the macular area after the acute stage of the disease. The clinical findings are similar to what the foreign report described. But there were no previous reports in China. CONCLUSION: We can establish the diagnosis on the base of clinical and fundus features associated with fluorescein angiographic findings. However, the etiology and pathology could not be identified. It required further research.

Acute Disease↗
PubMed1998

[The investigation of interaction for silver(I) ion with gamma-globulin by resonance spectroscopy].

The interaction for silver (I) ion with gamma-globulin has been investigated by resonance spectroscopy. It is shown that 2 or 4 coordination species for amino acid residues of gamma-globulin with Ag (I) ion were formed and their resonance spectra appear to be different in amide bands region. It has been studied that effect of reaction time on resonance Raman(RR) spectra in heat condition. Results showed that the intensity of RR has maximum at about 15 min of reaction, and after the time, Ag (I) ion on species will reduced to elemental silver.

Protein Binding↗
PubMed1998

Construction of Escherichia coli-Streptomyces shuttle expression vectors for gene expression in Streptomyces.

pIJ4123 and pIJ6021 are high-copy-number vectors for gene expression in Streptomyces. They contain a strong, thiostrepton-inducible promoter, PtipA. Two E. coli-Streptomyces shuttle vectors, pHZ1271 and pHZ1272, were constructed by inserting a replicon and bla gene from E. coli into pIJ4123 and pIJ6021, respectively. Both vectors were structurally stable either in E. coli or in Streptomyces lividans. To demonstrate the utility of pHZ1272, the hemoglobin gene of Vitreoscillia (vhb) was cloned into pHZ1272 and expressed in Streptomyces lividans. The expression product (VHb) was detected by Western blotting and carbon monoxide binding activity analysis.

Amino Acid Sequence↗
PubMed1997

GFRalpha-2 and GFRalpha-3 are two new receptors for ligands of the GDNF family.

The receptor for glial cell line-derived neurotrophic factor (GDNF) consists of GFRalpha-1 and Ret. Neurturin is a GDNF-related neurotrophin whose receptor is presently unknown. Here we report that neurturin can bind to either GFRalpha-1 or GFRalpha-2, a novel receptor related to GFRalpha-1. Both GFRalpha-1 and GFRalpha-2 mediate neurturin-induced Ret phosphorylation. GDNF can also bind to either GFRalpha-1 or GFRalpha-2, and activate Ret in the presence of either binding receptor. Although both ligands interact with both receptors, cells expressing GFRalpha-1 bind GDNF more efficiently than neurturin, while cells expressing GFRalpha-2 bind neurturin preferentially. Cross-linking and Ret activation data also suggest that while there is cross-talk, GFRalpha-1 is the primary receptor for GDNF and GFRalpha-2 exhibits a preference for neurturin. We have also cloned a cDNA that apparently codes for a third member of the GFRalpha receptor family. This putative receptor, designated GFRalpha-3, is closely related in amino acid sequence and is nearly identical in the spacing of its cysteine residues to both GFRalpha-1 and GFRalpha-2. Analysis of the tissue distribution of GFRalpha-1, GFRalpha-2, GFRalpha-3, and Ret by Northern blot reveals overlapping but distinct patterns of expression. Consistent with a role in GDNF function, the GFRalphas and Ret are expressed in many of the same tissues, suggesting that GFRalphas mediate the action of GDNF family ligands in vivo.

Amino Acid Sequence↗
PubMed1997

Adrenalectomy-induced granule cell death is predicated on the disappearance of glucocorticoid receptor immunoreactivity in the rat hippocampal granule cell layer.

In this study, we observed the changes of glucocorticoid receptor (GR)-immunoreactivity (ir) and cell death in the rat hippocampal granule cell layer at various periods after adrenalectomy (ADX). Our results revealed that all of the rats shortly after ADX showed a rapid loss of GR-ir and subsequent appearance of degenerating cells in the granule cell layer. One month after ADX, however, about 80% of the rats displayed a restoration of GR-ir and the absence of degenerating cells in the granule cell layer, and this phenomenon was successively noted for 6 months. Hippocampal structural destruction 3 and 6 months after ADX was found in about 20% of the rats with loss of GR-ir in the granule cell layer; the ADX rats with even weak GR-ir in this area had a normal hippocampus. The treatment of rats with synthetic GR agonist, dexamethasone, immediately after ADX prevented the loss of GR-ir and significantly reduced the number of degenerating cells in the granule cell layer. Our results clarified that granule cell death after ADX was necessarily accompanied by the disappearance of GR-ir in the granule cell layer, suggesting that ADX-induced granule cell death is predicated on the loss of GR-ir and that the presence of GR-ir in this area may be important for granule cell survival.

Adrenalectomy↗
PubMed1997

Preparation and Characterization of Surface-Covered Nanometer-Sized Catalyst by Carboxylate Phase Transfer

Surface-covered nanometer-sized CuO/Al2O3, CuO-ZnO/Al2O3, and CuO/ZnO catalysts were prepared by phase transfer with carboxylate. The surface-covered structure was studied using XPS, XRD, TEM, and high-resolution electron microscope. The results indicated that amorphous CuO and ZnO were dispersed on the surface of nanometer-sized Al2O3 particles in catalysts CuO-ZnO/Al2O3 and CuO/Al2O3, respectively. The thickness of its surface layer is about several angstroms. No spinel structure was found in the catalyst. The particle size of the surface-covered CuO/Al2O3 catalyst was about 2-3 nm. Al2O3 in the catalyst was amorphous. Surface-covered material CuO in the catalyst with low CuO content was also armophous. A large amount of copper carboxylate resulted in crystalline CuO and Cu2O. The protective ability of carboxylate to sol particles differs from the metal element of carboxylate. Copyright 1997 Academic Press. Copyright 1997Academic Press

Journal Article↗
PubMed1997

A DnaB intein in Rhodothermus marinus: indication of recent intein homing across remotely related organisms.

A dnaB gene encoding a homologue of the Escherichia coli DNA helicase DnaB was cloned and sequenced in the thermophilic eubacterium Rhodothermus marinus, predicting a DnaB protein that harbors an intein. This DnaB intein is 428 amino acid residues long, has several putative intein sequence motifs (including two putative endonuclease motifs), and is capable of protein splicing when produced in E. coli cells. The R. marinus DnaB intein is a close homologue of a DnaB intein in the cyanobacterium Synechocystis sp. strain PCC6803. The two inteins are positioned identically in their respective DnaB proteins. They also share a 54% sequence identity (74% sequence similarity) that is markedly higher than the 37% sequence identity shared by the extein sequences of the two DnaB proteins. Horizontal intein transfer (homing) is therefore invoked to relate these two DnaB inteins. The codon usage of R. marinus DnaB intein coding sequence differs markedly from the codon usages of its flanking extein coding sequences and other genes in the same genome, suggesting more recent acquisition of the DnaB intein in this organism.

Amino Acid Sequence↗
PubMed1997

The in vivo time course for elimination of adrenalectomy-induced apoptotic profiles from the granule cell layer of the rat hippocampus.

Although apoptotic cellular degeneration has been reported to be extremely rapid with the use of in vitro models, the time needed to clear apoptotic neurons in the in vivo brain is unknown. In this study we used a simple morphological approach to solve this problem. Four days after adrenalectomy (ADX), all of the operated rats morphologically displayed hippocampal granule cell apoptosis that was prevented completely by corticosterone replacement immediately after ADX. Therefore, we intravenously injected the rats with corticosterone 4 d after ADX and subsequently maintained them on corticosterone replacement in saline drinking water. This corticosterone replacement could protect healthy granule cells promptly and continuously against hormone-deficient apoptosis, because the normal glucocorticoid receptor immunoreactivity within the granule cell nuclei, which disappeared after ADX, was identified 1 hr after corticosterone replacement was started, and this effect persisted for several days. However, this corticosterone treatment could not prevent the irreversible apoptosis of the already degenerated granule cells at various stages of the same progressive apoptotic process. Then we successively traced the disappearance of apoptotic granule cells throughout the hippocampus at different time points by Nissl and silver staining. Given that the apoptotic cells at the earliest stage of the degenerating process when the ADX rats received corticosterone injection were the last to disappear, the period from corticosterone injection until the disappearance of the last degenerating debris of apoptotic cells was taken to represent the time course for elimination of apoptotic neurons in vivo. We discovered that the elimination of apoptotic granule cells took 72 hr.

Adrenalectomy↗
PubMed1997

Steroidogenic factor-1 is an essential transcriptional activator for gonad-specific expression of promoter I of the rat prolactin receptor gene.

The expression of the prolactin receptor is under the control of two putative tissue-specific (PI, gonads; PII, liver) and one common (PIII) promoters (Hu, Z. Z., Zhuang, L., and Dufau, M. L. (1996) J. Biol. Chem. 271, 10242-10246). The three promoter regions were co-localized to the rat chromosomal locus 2ql6, in the order 5'-PIII-PI-PII-3'. To investigate the mechanisms of gonad-specific utilization of PI, the promoter domain, regulatory cis-elements, and trans-factors were identified in gonadal cells. The promoter domain localized to the 152-base pair 5' of the transcriptional start site at -549 is highly active in gonadal cells but has minimal activity in hepatoma cells. It contains a steroidogenic factor 1 (SF-1) element (-668) that binds the SF-1 protein of nuclear extracts from gonadal cells and is essential for promoter activation. A CCAAT box (-623) contributes minimally to basal activity in the absence of the SF-1 element, and two adjacent TATA-like sequences act as inhibitory elements. Thus, PI belongs to a class of TATA-less/non-initiator gene promoters. These findings demonstrate an essential role for SF-1 in transcriptional activation of promoter I of the prolactin receptor gene, which may explain the tissue-specific expression of PI in the gonads but not in the liver and the mammary gland.

Animals↗
PubMed1997

Identification and characterization of a cyanobacterial DnaX intein.

A new intein is identified and characterized in the DnaX protein of Synechocystis sp. PCC6803. This cyanobacterial DnaX protein is a homologue of the intein-less 71-kDa tau-subunit of Escherichia coli DNA polymerase III and is related to eukaryotic DNA replication factor C (RFC). The 430-residue DnaX intein contains several putative intein sequence motifs and undergoes protein splicing when produced in E. coli cells. Its position in the DnaX protein is close to, but different from, positions of three inteins present in a DnaX-related RFC protein of Methanococcus jannaschii.

Amino Acid Sequence↗
PubMed1997

Basal cell carcinomas in mice overexpressing sonic hedgehog.

Mutations in the tumor suppressor gene PATCHED (PTC) are found in human patients with the basal cell nevus syndrome, a disease causing developmental defects and tumors, including basal cell carcinomas. Gene regulatory relationships defined in the fruit fly Drosophila suggest that overproduction of Sonic hedgehog (SHH), the ligand for PTC, will mimic loss of ptc function. It is shown here that transgenic mice overexpressing SHH in the skin develop many features of basal cell nevus syndrome, demonstrating that SHH is sufficient to induce basal cell carcinomas in mice. These data suggest that SHH may have a role in human tumorigenesis.

Animals↗