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Biomedical subjects

Y Hu

Publications and source records attributed to Y Hu.

At least 541 records · Page 30Linked to original sources
PubMed1995

The Arabidopsis MADS-box gene AGL3 is widely expressed and encodes a sequence-specific DNA-binding protein.

The Arabidopsis AGL3 gene was previously identified on the basis of sequence similarity to the floral homeotic gene AGAMOUS (AG), which encodes a protein with a conserved MADS domain that is also found in human and yeast transcription factors (SRF and MCM1, respectively). Analysis of newly isolated full-length cDNA clones as well as genomic clones indicates that AGL3 is indeed a MADS-box gene with a general intron-exon structure similar to other plant MADS-box genes. However, unlike the others, which are expressed specifically in flowers, AGL3 is expressed in all above-ground vegetative organs, as well as in flowers, but not in roots. Furthermore, since AGL3 is MADS-domain protein, it is likely that it is also a DNA-binding protein regulating transcription. To characterize AGL3 as a DNA-binding protein in vitro, we expressed the AGL3 protein in Escherichia coli, and characterized its DNA-binding properties. We show that AGL3 binds to sequences which resemble the target sequences of SRF and MCM1, and have determined the consensus sequence to which AGL3 binds using random oligonucleotides. These results suggest that AGL3 is a widely distributed DNA-binding protein, which may be involved the transcriptional regulation of genes in many cells.

Amino Acid Sequence↗
PubMed1995

Proteins functioning in synaptic transmission at the sensory to motor synapse of Aplysia.

Over expression of Aplysia synaptotagmin in acutely dissected cholinergic neurons from the buccal ganglia, or in primary co-cultures of glutaminergic sensory neurons and motor neurons, causes a reduction synaptic transmission. Anti-sense oligonucleotide treatment of similar cultures produced an enhancement of synaptic transmission. The interaction between Aplysia VAMP/synaptobrevin and syntaxin is reconstructed using the yeast two hybrid system, and used to identify amino acid residues of VAMP/synaptobrevin that are required for this interaction. Point mutations around residue 50, close to the site of cleavage by botulinum toxins specifically disrupt the interaction with syntaxin. An additional VAMP/synaptobrevin binding protein, VAP33, is identified using the yeast two hybrid system. Intracellular injection of VAP33 specific antisera inhibits synaptic transmission in sensory-motor neuron co-cultures.

Amino Acid Sequence↗
PubMed1995

Synthesis of (17R)- and (17S)-17-hydroxy-14, 15-secoandrost-4-en-15-yn-3-one and the X-ray crystal structure of the (17S)-diastereomer.

(17R,S)-17-Hydroxy-14,15-secoandrost-4-en-15-yn-3-one has been shown previously to be a mechanism-based inactivator of rat liver 3 alpha-hydroxysteroid dehydrogenase. This manuscript describes the synthesis of this diastereomeric 14,15-secosteroid from [2S-2 alpha,4a alpha,4b beta,10a beta)]- 1,2,3,4a,4b,7,9,10,10a-decahydro-2,4b-dimethyl-7-oxo-2-phenanth renecarboxylic acid methyl ester. The separation of this diastereomeric 14,15-secosteroid into (17R)- and (17S)-17-hydroxy-14,15-secoandrost-4-en-15-yn-3-one was accomplished by HPLC separation of the (S)-1-[(4-methylphenyl)sulphonyl]-2-pyrrolidinecarboxylate derivatives on a silica column. The crystal structure of (17S)-17-hydroxy-14,15-secoandrost-4-en-15-yn-3-one was then solved by X-ray diffraction analysis to establish unambiguously the absolute configuration of the diastereomeric 14,15-secosteroid.

3-Hydroxysteroid Dehydrogenases↗
PubMed1995

Synthesis of (17R)- and (17S)-17-hydroxy-14, 15-secoandrost-4-en-15-yn-3-one and the X-ray crystal structure of the (17S)-diastereomer.

(17R,S)-17-Hydroxy-14,15-secoandrost-4-en-15-yn-3-one has been shown previously to be a mechanism-based inactivator of rat liver 3 alpha-hydroxysteroid dehydrogenase. This manuscript describes the synthesis of this diastereomeric 14,15-secosteroid from [2S-(2 alpha,4a alpha,4b beta, 10a beta)]- 1,2,3,4a,4b,7,9,10,10a-decahydro-2,4b-dimethyl-7-oxo-2-phenanth renecarboxylic acid methyl ester. The separation of this diastereomeric 14,15-secosteroid into (17R)- and (17S)-17-hydroxy-14,15-secoandrost-4-en-15-yn-3-one was accomplished by HPLC separation of the (S)-1-[(4-methylphenyl)sulphonyl]-2-pyrrolidinecarboxylate derivatives on a silica column. The crystal structure of (17S)-17-hydroxy-14,15-secoandrost-4-en-15-yn-3-one was then solved by X-ray diffraction analysis to establish unambiguously the absolute configuration of the diastereomeric 14,15-secosteroid.

3-Hydroxysteroid Dehydrogenases↗
PubMed1995

Blastocyst development in co-culture: development and morphological aspects.

A retrospective study was undertaken to determine if initial culture conditions and embryo quality had an effect on subsequent blastocyst development in co-culture for cryopreservation. The apparent effects of freeze-thawing on blastocysts at the ultrastructure level were also observed. On day 3 of culture, embryos were categorized into two groups based on their morphological attributes. Results suggest that the initial culture environment of embryos up to day 3 (5- to 8-cell stage) did not affect the subsequent rate of blastocyst formation in co-culture. However, the initial embryo quality had an impact on blastocyst formation and quality. On day 5.5, 90% (60/67) of the optimal quality embryos (six to eight blastomeres with minimal or no fragmentation on day 3) had attained the blastocyst stage, which was greater (P < 0.01) than the 55% (31/56) observed with the sub-optimal embryos (five to eight blastomeres with 30-50% fragmentation on day 3). Furthermore, 66% (44/67) of embryos initially graded as optimal were suitable for cryopreservation, which was greater (P < 0.01) than attained with embryos of lesser quality (22/56; 39%). At the ultrastructural level, the polarized distribution of plasma membrane microvilli was retained, as was the integrity of the nuclear membrane following thawing.

Blastocyst↗
PubMed1995

A combined genetic and biochemical approach to mammalian signal transduction.

The last five years have seen a rapid increase in interest and understanding of signal transduction pathways. While the description of such pathways has become more detailed and complex, a number of consistent findings have emerged. Modular domains, such as SH2 and SH3 domains, are present on a wide variety of proteins and mediate specific protein-protein interactions. By defining the interaction mediated by such domains, a 'language' of interaction between proteins in signalling pathways is emerging. As more signalling proteins are identified it has become apparent that most oncogenes and tumour suppressor genes are components of major signalling pathways. Therefore, studies on the basic biology of signal transduction are having a direct impact on our understanding of cell transformation. With the characterisation of signalling pathways in a range of organisms, it has also become obvious that signalling pathways are ancient and have been highly conserved over the last billion years of evolution. A practical result of this finding has been the ability to exploit results obtained in genetically tractable invertebrate species such as C. elegans and Drosophila melanogaster to investigate signal transduction in mammals. This is an approach we have emphasized in our investigation of signal transduction by tyrosine kinase receptors in human and mouse cells. Results obtained in these studies with the Sos and Siah proteins are reviewed.

Animals↗
PubMed1995

The rotavirus nonstructural glycoprotein NSP4 mobilizes Ca2+ from the endoplasmic reticulum.

We previously reported that expression of rotavirus nonstructural glycoprotein NSP4 is responsible for an increase in cytosolic free Ca2+ concentration ([Ca2+]i) in Spodoptera frugiperda (Sf9) insect cells (P. Tian, Y. Hu, W. P. Schilling, D. A. Lindsay, J. Eiden, and M. K. Estes, J. Virol. 68:251-257, 1994). The purpose of the present study was to determine the mechanism by which NSP4 causes an increase in [Ca2+]i by measuring the permeability of the cytoplasmic and endoplasmic reticulum (ER) membranes in recombinant-baculovirus-infected Sf9 cells. No obvious change in plasmalemma permeability to divalent cations was observed in cells expressing NSP4 compared with that in cells expressing another rotaviral glycoprotein (VP7) when the influx of Ba2+, a Ca2+ surrogate, was monitored. The basal Ca2+ permeability of the internal Ca2+ store was evaluated by measuring the release of Ca2+ induced by ionomycin, a Ca2+ ionophore, or thapsigargin, an inhibitor of the ER Ca(2+)-ATPase pump, following suspension of the cells in Ca(2+)-free extracellular buffer. Releasable Ca2+ decreased with time to a greater extent in cells expressing NSP4 compared with that in cells expressing VP7, suggesting that NSP4 increases the basal Ca2+ permeability of the ER membrane. To determine the possible mechanism by which NSP4 increases ER permeability, purified NSP4 protein or a 22-amino-acid synthetic peptide consisting of residues 114 to 135 (NSP4(114-135) was added exogenously to noninfected Sf9 cells during measurement of [Ca2+]i. Both NSP4 and the NSP4(114-135 peptide produced a time-dependent increase in [Ca2+]i that was attenuated by prior inhibition of phospholipase C with U-73122. Pretreatment of the cells with thapsigargin completely blocked the increase in [Ca2+]i produced by NSP4(114-135, but the peptide only partially reduced the change in [Ca2+]i produced by thapsigargin. No changes in [Ca2+]i were seen in cells treated with control peptides. These results suggest that (i) exogenous NSP4 increases [Ca2+]i through the activation of phospholipase C, (ii) Ca2+ release by exogenous NSP4 is from a store that is a subset of the thapsigargin-sensitive compartment, and (iii) amino acid residues 114 to 135 of NSP4 are sufficient for this activity. In contrast to exogenous NSP4, the mechanism by which endogenously expressed NSP4 increases [Ca2+]1 appears to be unrelated to phospholipase C, since no effect of U-73122 was seen on the elevated [Ca2+]1 in cells expressing NSP4 and exogenously applied NSP4(114-135) caused a further increase in [Ca2+]1 in cells expressing NSP4 protein.(ABSTRACT TRUNCATED AT 400 WORDS)

Amino Acid Sequence↗
PubMed1995

The Saccharomyces cerevisiae Leu3 protein activates expression of GDH1, a key gene in nitrogen assimilation.

The Leu3 protein of Saccharomyces cerevisiae has been shown to be a transcriptional regulator of genes encoding enzymes of the branched-chain amino acid biosynthetic pathways. Leu3 binds to upstream activating sequences (UASLEU) found in the promoters of LEU1, LEU2, LEU4, ILV2, and ILV5. In vivo and in vitro studies have shown that activation by Leu3 requires the presence of alpha-isopropylmalate. In at least one case (LEU2), Leu3 actually represses basal-level transcription when alpha-isopropylmalate is absent. Following identification of a UASLEU-homologous sequence in the promoter of GDH1, the gene encoding NADP(+)-dependent glutamate dehydrogenase, we demonstrate that Leu3 specifically interacts with this UASLEU element. We then show that Leu3 is required for full activation of the GDH1 gene. First, the expression of a GDH1-lacZ fusion gene is three- to sixfold lower in a strain lacking the LEU3 gene than in an isogenic LEU3+ strain. Expression is restored to near-normal levels when the leu3 deletion cells are transformed with a LEU3-bearing plasmid. Second, a significant decrease in GDH1-lacZ expression is also seen when the UASLEU of the GDH1-lacZ construct is made nonfunctional by mutation. Third, the steady-state level of GDH1 mRNA decreases about threefold in leu3 null cells. The decrease in GDH1 expression in leu3 null cells is reflected in a diminished specific activity of NADP(+)-dependent glutamate dehydrogenase. We also demonstrate that the level of GDH1-lacZ expression correlates with the cells' ability to generate alpha-isopropylmalate and is lowest in cells unable to produce alpha-isopropylmalate. We conclude that GDH1, which plays an important role in the assimilation of ammonia in yeast cells, is, in part, activated by a Leu3-alpha-isopropylmalate complex. This conclusion suggests that Leu3 participates in transcriptional regulation beyond the branched-chain amino acid biosynthetic pathways.

Base Sequence↗
PubMed1995

Decreased levels of adenylate cyclase contribute to the down-regulation of beta-adrenergic signal transduction in the salivary glands of the non-obese diabetic (NOD) mouse.

Stimulation of salivary gland secretion by treatment of NOD mice with the beta-adrenergic receptor agonist, isoproterenol, was previously shown to cause a lower accumulation of intracellular cAMP than that found that in BALB/c controls (Hu et al., 1994, Am. J. Physiol. 266: G433). This was, in part, due to decreased levels of beta-adrenergic receptor localized in the plasma membrane. In the present investigation, basal levels of cAMP in the salivary glands of NOD mice were found to be similar to controls, while direct stimulation of adenylate cyclase by incubation of isolated membranes with forskolin showed a reduced cAMP accumulation in NOD mice versus BALB/c control mice. Using direct [3H]-forskolin binding, it was determined that the plasma membranes of NOD mice salivary glands contain reduced levels of membrane-associated adenylate cyclase.

Adenylyl Cyclases↗
PubMed1995

Functional assessment of Chinese children with the ABILITIES index.

The diagnosis and classification of children with disabilities are persistent concerns in paediatric and habilitative services. These concerns are magnified in international contexts and restrict comparative research and policy development. Even within classifications such as mental retardation, hearing impairment and physical impairment, children can vary widely in the nature and severity of manifested conditions. In the fields of disability and rehabilitation there is a growing interest in functional measurement. Accompanying this awareness is a corresponding recognition of the value of classification approaches which are compatible with the WHO framework of the International Classification of Impairments, Disabilities, and Handicaps. This paper examines issues pertaining to the classification of children with disabilities and describes the development of the ABILITIES Index, a functional assessment measure yielding a profile of individual characteristics. The cross-cultural applicability of the measure is documented on the basis of data for children in the People's Republic of China.

Adolescent↗
PubMed1995

[Zhang Taiyan, leader of TCM transform].

Being an influential figure of old democratic revolutionalist, thinker and scholar, Mr. Zhang Taiyan is also a medical man. He lived in a period of modern turbulence with introduction of western medicine into China, while TCM was confronting the challenge. He advocated the mutual absorption so as to be benefitted from both TCM and western medicine. By adopting some of his discourses of over one hendred pieces on Shang Han Lun, poet, essays, condolescent poet to form a thesis, it can be shown that his medical undertakings was but a part of his whole career.

China↗
PubMed1995

[Effect of 153Sm-EDTMP on hematopoiesis and vital organs of 93 patients with bone tumor].

In the present study data on blood cell count, serum biochemistry, electrolyte, enzyme and vital organs of 93 patients with bone tumor or metastasis were investigated before and after treatment with 153Sm-EDTMP. The results showed that, 7 days and 30 days after the administration of 153Sm-EDTMP (< 29.6 MBq) (0.8 mCi/kg), the levels of hemoglobin, WBC lymphocyte count, and the liver and kidney function of all patients were not significantly different from the baseline data before treatment (P > 0.05). Although at 7 days, there was a declination of the granulocyte count, it returned to normal at 30 days (P > 0.05). The platelet count was significantly decreased (0.05 > P > 0.01). at 30 days after the administration of 153Sm-EDTMP. Thirteen patients received 74-185 MBq (2-5mCi/kg) and their myelo biopsies at 3 and 18 months showed no sign of acute or chronic toxicosis.

Adult↗
PubMed1995

Repeated radial keratotomy.

38 cases 59 eyes received repeated radial keratotomy in which the secondary incisions were performed along the scars of old incisions. The average follow-up after the reoperation was 13 months. Before reoperation, the mean spherical equivalent of the refraction was -3.78D and the mean keratometry was 40.15D. 13 months after the reoperation, the mean spherical equivalent of the refraction decreased by 2.30D, and the mean keratometry decreased by 2.04D. After the reoperation, the mean uncorrected visual acuity increased by 5 lines. There was no relationship between the therapeutic effect of the reoperation and the degree of initial myopia or pre-reoperative keratometry. The repeated radial keratotomy can decrease the degree of astigmatism and its complications are few.

Adult↗
PubMed1995

Regulation of human clotting factor IX cDNA expression in transgenic mice.

To study the expression of human clotting factor IX cDNA in transgenic mice, which is an essential work on gene therapy for hemophilia B, 3 recombinant constructions containing different lengths of human clotting factor IX cDNA have been introduced into the cultured cells. All of the recombinant constructions were found to be expressed well in vitro. They were then microinjected into the male pronuclei of the fertilized mouse eggs respectively for generating transgenic mice. Unfortunately, none of them was expressed in any transgenic mice. These results show that the expression of the human clotting factor IX cDNA in the transgenic mice can be determined by cis regulatory element(s). As compared with the results from other related works, it is suggested that the cis regulatory element(s) is resided in the 5'-end non-coding region.

Animals↗
PubMed1995

[Research on rectal administration of bark of official Magnolia].

Fluorescence assay was applied to the determination of magnolol in rabbit blood, and the best way to administer the bark of official magnolia per rectal was established by orthogonal test. Then the two routes of administration were compared by AUC of magnolol and per rectal was found better than P.O. In addition, the modified isolated rectum-bag method was applied successfully to the research on rectal administration of bark of official magnolia.

Administration, Rectal↗