Biomedical subjects

Y Zhou

Publications and source records attributed to Y Zhou.

At least 505 records · Page 28Linked to original sources

PubMed1998

Apolipoprotein-E deficiency results in an altered stress responsiveness in addition to an impaired spatial memory in young mice.

It has been suggested that Alzheimer's disease (AD) is associated with an altered neurotrophic function of apolipoprotein-E (ApoE) and abnormal neuroendocrine activities. In the present study we investigated stress responsiveness of ApoE-deficient mice. Firstly, two sessions of restraint were introduced, 20 min per day for two (session 1) and three (session 2) consecutive days. In session 1, there was no difference between genotypes in open-field activity in response to restraint stress. In session 2, spatial memory was assessed in a Morris Water Maze 'Place Learning Set' task immediately following stress. Restraint stress caused a significant impairment of spatial memory in wild-type mice. The non-restraint ApoE-deficient mice showed a severe impairment of spatial memory similar to that of the restrained wild-type mice. Restraint stress had no obvious effect on spatial memory in ApoE-deficient mice until the third day of testing, when there was a decrease in reference memory compared with their non-restraint controls. In addition, the first session of restraint stress had an inhibitory effect on food intake in wild-type but not ApoE-deficient mice, and a longer-lasting effect on body weight in the wild-type than ApoE-deficient mice. ApoE-deficient mice showed a weaker corticosterone response to the initial restraint stress and a slower descending rate in serum corticosterone level during a 30-min post-stress period than their wild-type controls. However, higher baseline levels and stronger corticosterone responses were observed in ApoE-deficient mice than in wild-type mice when exposed to repeated restraint stress. The expression of ApoE mRNA was upregulated in the hypothalamus in wild-type mice exposed to repeated restraint stress. Taken together, these results demonstrate that ApoE deficiency causes a memory impairment and an altered stress responsiveness in mice.

Analysis of Variance↗

PubMed1998

Arginine residues in the C-terminus of HIV-1 Vpr are important for nuclear localization and cell cycle arrest.

HIV-1 viral protein R (Vpr) is predominantly localized to the nucleus and plays an important role for viral preintegration complex import into the nucleus. In this study, we investigated the influence on subcellular localization of Arg residues in the C-terminus of Vpr. Consistent with previous studies, about 90% of the cells manifested diffuse nuclear staining in the Vpr-expressed cells. Besides diffuse nuclear staining, punctate perinuclear staining, and punctate cytoplasmic staining were also observed in the immunofluorescence studies. Deletion of the Ser-Arg-lle-Gly residues (amino acids 79-82; SRIG) had no effect on the Vpr localization. However, deletion of the Arg-Gln-Arg-Arg residues (amino acids 85-88; RQRR) resulted in a smooth perinuclear staining pattern. Substitution of five Arg residues with Asn (amino acids 80, 85, 87, 88, and 90; R-->N5) resulted in a diffuse cytoplasmic staining. Subcellular fractionation analyses support the immunofluorescence staining results. These findings indicate that the C-terminal Arg residues of HIV-1 Vpr play an important role for Vpr nuclear localization. All the Vpr mutants were appropriately expressed, exhibited no significant defect on the protein stability, and were incorporated efficiently into virus-like particles. Both SRIG and R-->N5 mutants lost their cell cycle arrest activities and the RQRR deletion only exhibited a low level of cell arrest activity. Therefore, the Arg residues in the HIV-1 Vpr C-terminus are important for Vpr nuclear localization and cell cycle arrest, but had no effect on protein stability or Vpr incorporation into virus-like particles.

Amino Acid Sequence↗

PubMed1998

Mechanism for the suppression of the mammalian stress response by genistein, an anticancer phytoestrogen from soy.

BACKGROUND: Soy products contain high levels of genistein, a phytoestrogen that is a potent inhibitor of cell proliferation and angiogenesis. Genistein has been found to inhibit the growth of carcinogen-induced cancers in rats and human leukemia cells transplanted into mice. The induction of stress proteins (e.g., glucose-related proteins and heat shock proteins) in tumor cells has been shown to protect them against programmed cell death; this stress response is inhibited by genistein. The mechanism(s) by which genistein affects certain stress response genes was explored in this study. METHODS: Mammalian cell cultures were treated with azetidine, a proline analog, which elicits a stress response that includes the induction of the expression of glucose-regulated protein GRP78 and heat shock protein HSP70. The effects of azetidine and/or genistein treatment on cellular levels of grp78 and hsp70 messenger RNAs and proteins were measured by northern blot hybridization and western blot analyses, respectively, and the binding of nuclear factors to sequence motifs in the upstream (promoter) regions of these two genes were examined by electrophoretic mobility shift assays. RESULTS: Genistein antagonized the binding of a specific transcription factor, nuclear factor-Y/CCAAT binding factor (NF-Y/CBF), to the CCAAT sequence element most proximal to the transcription start sites in the hsp70 and grp78 promoters; this CCAAT element was previously shown to be necessary for full-stress inducibility of both genes. Treatment of cells with genistein converted NF-Y/CBF into a nonbinding, transcriptionally inactive form. IMPLICATION: The anticancer effects of genistein may be related to its ability to reduce the expression of stress response-related genes.

Animals↗

PubMed1998

Co-expression of human adenosine deaminase and multidrug resistance using a bicistronic retroviral vector.

Current gene therapy protocols designed to treat adenosine deaminase (ADA) deficiency and other metabolic disorders suffer from low-efficiency delivery to target cells and a lack of long-term stability in expression of the therapeutic proteins. These problems may be resolved by use of an in vivo dominant selection. The multidrug transporter (MDR1) has been suggested as a useful selective marker for gene therapy. In this work, we co-expressed ADA and MDR1 cDNA in a retroviral vector using an internal ribosome entry site (IRES) from encephalomyocarditis virus. This system produced a bicistronic mRNA containing both ADA and MDR1, which enables co-expression of ADA and MDR1, and also allows the two proteins to be translated separately. After in vitro selection using a cytotoxic MDR1 substrate, vincristine, we demonstrated that functional ADA was co-expressed with MDR1 in proportion to the expression level of MDR1, whereas MDR1 expression was proportional to the stringency of the vincristine selection. Because the efficiency of IRES-dependent translation was much lower than that of cap-dependent translation in this system, we observed lower expression of the genes positioned after the IRES. This asymmetric expression caused a lower viral titer when MDR1 was placed downstream from the IRES, but it also provided a way of modulating the relative expression of ADA and MDR1. The retroviral system described in this work may serve as a useful tool to evaluate the strategies involving in vivo dominant selection for gene therapy of ADA-deficient patients.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed1998

[A study of genetic patterns of idiopathic epilepsy].

OBJECTIVE: To explore genetic patterns of idiopathic epilepsy (IEP). METHODS: Using familial analysis, tests for multifactorial inheritance and segregation analysis, we studied 210 pedigrees with IEP found in a population survey in Shangdong province. RESULTS: The genetic pattern of IEP is not polygenic but is mainly influenced by autosomal recessive disorders. The results of segregation analysis indicate that the genetic pattern of U*U multiplex families and U*A group is autosomal recessive. Only a few cases in U*U group may accept the assumption of autosomal recessive inheritance while the other are sporadic cases. The frequency of sporadic cases is approximately 78.5%. Genetic heterogeneity may influence U*U(f) group and U*U group. CONCLUSION: Further and careful empirical scrutiny of U*U(f) group and the sporadic cases in U*U group offers the best hope for getting a clear understanding of genetic patterns and mechanisms in IEP.

Epilepsy↗

PubMed1998

Differential regulation of levels of nicotinic receptor subunit transcripts in adult sympathetic neurons after axotomy.

Axotomy of adult peripheral neurons produces decreases in the levels of transcripts for a number of proteins involved in synaptic transmission. For example, tyrosine hydroxylase and neuropeptide Y mRNA decrease in axotomized sympathetic neurons in the superior cervical ganglion (SCG). In the present study, the effects of axotomy on the expression of nicotinic receptor subunit transcripts were examined in the SCG and the results were compared to those produced by deafferentation and explantation. Normally, neurons in the SCG express five different nicotinic subunits: alpha3, alpha5, alpha7, beta2, and beta4. Forty-eight hours after axotomy in vivo or explantation, dramatic decreases in these transcripts were seen, except for beta2, which increased. In contrast, deafferentation of the SCG had negligible effects on any of these transcripts. Both leukemia inhibitory factor (LIF) and nerve growth factor (NGF) have been shown to play a role in the decrease in neuropeptide Y mRNA expression after axotomy. In the cases of these nicotinic receptor transcripts, however, similar decreases were seen in wild-type and LIF knockout animals. Furthermore, administration of an antiserum to NGF in intact animals produced no changes in transcript levels. On the other hand, providing exogenous NGF to axotomized SCG in vivo or in explant cultures partially prevented the decreases in the transcripts for alpha3, alpha5, alpha7, and beta4. These data indicate that axotomy produces dramatic decreases in the expression of several nicotinic receptor subunit transcripts, and that the molecular signals underlying these changes differ from those previously shown to mediate the decrease in neuropeptide Y expression.

Animals↗

PubMed1998

Finite element analysis of diffusional drug release from complex matrix systems. II. Factors influencing release kinetics.

This work concentrated on the analysis of several factors influencing the kinetics of diffusional drug release from complex matrix devices, such as convex tablets and rings, into a finite volume. These factors include initial drug concentration distribution, anisotropic matrix, and time- and concentration-dependent diffusion coefficients. The individual and comprehensive effects of these factors on the release kinetics were investigated by the finite element method. Errors introduced by neglecting drug diffusion through the ends of edges of cylindrical devices were estimated by comparison of the 1-D models with the 2-D cylinder model. The influence of side-wall coating on the accuracy of the prediction of release profiles by the 1-D slab model for cylindrical devices was studied using various coating materials of different permeabilities. The analyses carried out in this work could assist the design of the complex matrix systems required for controlled drug release.

Chemistry, Pharmaceutical↗

PubMed1998

Expression and function of alpha1-adrenoceptor subtypes in the porcine renal artery.

We investigated the expression and function of alpha1-adrenoceptor subtypes in the porcine renal artery. Reverse transcription polymerase chain reaction (RT-PCR) and nucleotide sequencing indicated that the mRNAs for alpha1a- and alpha1b-adrenoceptors were expressed in the porcine renal artery. Chloroethylclonidine, an alpha1B- and alpha1D-adrenoceptor antagonist, partially inhibited the phenylephrine-induced contraction, while 3 nM BMY 7378 (8-[2-[4-(2-methoxyphenyl)-1-piperazinyl]ethyl]-8-azaspiro[4.5]dec ane-7,9-dione dihydrochloride), an alpha1D-adrenoceptor antagonist, had no effect. In contrast, 5-methylurapidil, an alpha1A-adrenoceptor antagonist, induced a rightward shift of the phenylephrine concentration-response curve. The simultaneous measurement of cytosolic Ca2+ concentration ([Ca2+]i) and tension revealed that chloroethylclonidine pretreatment abolished the phenylephrine-induced increases in [Ca2+]i and tension in the Ca2+-free solution. The application of 5-methylurapidil (3 nM) to the chloroethylclonidine-pretreated strips completely inhibited the 3 microM phenylephrine-induced [Ca2+]i and tension increase in normal PSS. We concluded that both alpha1A- and alpha1B-adrenoceptors mediate the phenylephrine-induced contraction of the porcine renal artery accompanied by an increase in [Ca2+]i, and that alpha1A-adrenoceptors cause Ca2+ influx whereas alpha1B-adrenoceptors mainly mediate Ca2+ release.

Adrenergic alpha-1 Receptor Antagonists↗

PubMed1998

The CC chemokine I-309 inhibits CCR8-dependent infection by diverse HIV-1 strains.

Using a chemokine receptor model based on known receptor sequences, we identified several members of the seven transmembrane domain G-protein superfamily as potential chemokine receptors. The orphan receptor ChemR1, which has recently been shown to be a receptor for the CC chemokine I-309, scored very high in our model. We have confirmed that I-309, but not a number of other chemokines, can induce a transient Ca2+ flux in cells expressing CCR8. In addition, the human erythroleukemic cell line K562 responded chemotactically in a dose-responsive manner to this chemokine. Since several chemokine receptors have been shown to be required as coreceptors for HIV-1 infection, we asked whether human immunodeficiency virus type 1 (HIV-1) could efficiently utilize CCR8. Here we show that the CCR8 receptor can serve as a coreceptor for diverse T-cell tropic, dual-tropic, and macrophage-tropic HIV-1 strains and that I-309 was a potent inhibitor of HIV-1 envelope-mediated cell-cell fusion and virus infection. Furthermore, we show by flow cytometry and immunohistochemistry that antibodies generated against the CCR8 receptor amino-terminal peptide cross-reacted with U-87 MG cells stably expressing CCR8, THP-1 cells, HL-60 cells, and human monocytes, a target cell for HIV-1 infectivity in vivo.

Amino Acid Sequence↗

PubMed1998

Angiotensinogen gene and hypertension in Chinese.

The renin-angiotensin system plays a major role in regulating blood pressure and maintaining electrolyte and volume homeostasis. Previously, the angiotensinogen gene, which encodes the key substrate for renin within this system, has been reported linked to and associated with essential hypertension in White Europeans, African-Caribbeans, and Japanese. Therefore, we investigated whether the angiotensinogen gene might be similarly implicated in the pathogenesis of essential hypertension in Chinese by carrying out linkage analysis in 310 hypertensive sibling pairs. Genotypes for two diallelic DNA polymorphisms observed at amino acid residues 174 (T174M) and 235 (M235T) within the coding sequence and for two highly informative dinucleotide (GT)-repeat sequences (one in the 3' flanking region, and one at a distance of 6.1 cM from the gene) were determined. Affected sibpair analysis conducted according to three different algorithms (S.A.G.E./SIBPAL, MAPMAKER/ SIBS, and APM methods) revealed no evidence for linkage of the angiotensinogen gene to hypertension. Our data indicate that molecular variants of this gene do not appear to contribute materially to the pathogenesis of primary hypertension among Chinese (a notion supported by concomitant, direct estimates of power), and that the disease relevance of this gene may vary therefore depending on ethnicity.

Alleles↗

PubMed1998

Fluorescence in situ hybridization analysis of chromosome 12 anomalies in semen cells from patients with carcinoma in situ of the testis.

Carcinoma in situ (CIS) of the testis is the precursor of seminomas and non-seminomatous germ cell tumours of the adult testis. A marked cytogenetic anomaly, the isochromosome of the short arm of chromosome 12 [i(12p)], has been demonstrated in over 80 per cent of all histological varieties of testicular germ cell tumours (TGCTs). In the remaining group of i(12p)-negative TGCTs, an overrepresentation of chromosome 12p sequences has been found. The i(12p) chromosome and overrepresentation of 12p sequences in CIS cells have also been reported. In order to establish whether numerical and/or structural aberrations of chromosome 12 can be found in CIS cells exfoliated into seminal fluid, semen specimens from ten patients with CIS lesions were investigated using bicolour double fluorescence in situ hybridization (FISH). The two DNA probes used, p alpha 12H8 and YAC 5, specifically detect the centromeric region of chromosome 12 and a subregion, p11.2-p12.1, on the short arm of chromosome 12, respectively. Ejaculates of ten azoospermic or oligozoospermic infertile males, presumably CIS-free, were used as negative controls. Nuclei exhibiting three or more chromosome 12 signals were found to be present in a significantly larger number in the patient samples than in the control samples. Nuclei with five or more chromosome 12 signals were observed in eight out of the ten patients. Morphologically similar arrangements to i(12p) were observed in some of the ejaculates. These results demonstrate the potential of FISH in the early detection of CIS and TGCTs in males at high risk.

Adult↗

PubMed1998

Dual functions of the heartless fibroblast growth factor receptor in development of the Drosophila embryonic mesoderm.

The Drosophila embryonic mesoderm forms by invagination of the ventral-most blastoderm cells. Subsequent development of this germ layer involves the dorsolateral migration of the internalized cells and expansion by cell division, followed by the specification of particular cell fates through the coordinate actions of both intrinsic and extrinsic regulatory mechanisms. The latter include several intercellular signals that function across germ layers. These processes combine to generate a diversity of mesodermal sub-types, including the cardial and pericardial cells of the heart or dorsal vessel, a complete set of somatic muscle founders each with its unique identity, a population of cells that form the visceral musculature, and other cells that develop into hemocytes and the fat body. Here, we review recent evidence for the involvement of a fibroblast growth factor receptor (FGFR) encoded by the heartless (htl) gene in early directional migration of the Drosophila mesoderm. In addition, we provide new data that 1) demonstrate a second role for Htl in promoting the specification of the precursors to certain cardiac and somatic muscle cells in the Drosophila embryo, independent of its cell migration function, 2) suggest that Ras and at least one other signal transduction pathway act downstream of Htl, and 3) establish a functional relationship between the Ras pathway and Tinman (Tin), a homeodomain factor that is essential for specifying some of the same dorsal mesodermal cells that are dependent on Htl. Finally, parallels between requirements for FGFR signaling in Drosophila and vertebrate mesoderm development are considered.

Animals↗

PubMed1998

Application of capillary electrophoresis, liquid chromatography, electrospray-mass spectrometry and matrix-assisted laser desorption/ionization - time of flight - mass spectrometry to the characterization of recombinant human erythropoietin.

High performance capillary electrophoresis (HPCE), high performance liquid chromatography (HPLC), matrix-assisted laser desorption/ionization - time of flight - mass spectrometry (MALDI-TOF-MS), on-line CE-electrospray ionization-mass spectrometry (CE-ESI-MS) and on-line LC-ESI-MS have been employed to characterize a heterogeneous glycoprotein, recombinant human erythropoietin (rHuEPO) expressed from Chinese hamster ovary (CHO) cells. The analysis was demonstrated through two specific levels of detail: the intact protein and tryptic digests of the protein. Six glycoforms of rHuEPO were separated by HPCE; seventeen tryptic fragments in a total of 21 nonglycosylated and glycosylated peptides were characterized; the O-linked glycopeptides were analyzed directly by CE-ESI-MS and LC-ESI-MS. In particular, four glycans of O-acetylation of sialic acid were identified in the O-linked glycosylated fragments. The molecular weight of rHuEPO was accurately determined by MALDI-TOF-MS.

Amino Acid Sequence↗

PubMed1998

Lidocaine prolongs the safe duration of circulatory arrest during deep hypothermia in dogs.

PURPOSE: To test the hypothesis that lidocaine prolongs the safe period of circulatory arrest during deep hypothermia. METHODS: Sixteen dogs were subjected to cooling, first surface cooling to 30 degrees C and then core cooling to 20 degrees C rectal temperature). The circulation was then stopped for 90 min. In the lidocaine group, 4 mg.kg-1 lidocaine was injected into the oxygenator two minutes before circulatory arrest and 2 mg.kg-1 at the beginning of reperfusion and rewarming. The control group received equivalent volumes of normal saline. Post-operatively, using a neurological deficit scoring system (maximum deficit score-100; minimum-zero indicating that no scored deficit could be detected). Neurological function was evaluated hourly for six hours and then daily for one week, the pharmacokinetic parameters were calculated using one compartment model. RESULTS: On the seventh day, the neurological deficit score and overall performance were better in the lidocaine (0.83 +/- 2.04) than in the control group (8.33 +/- 4.08 P < 0.05). During the experiment, the base excess values were also better in the lidocaine than in the control group (at 30 min reperfusion: -4.24 +/- 1.30 vs -8.20 +/- 2.82 P < 0.01, at 60 min reperfusion was -3.34 +/- 1.87 vs -7.52 +/- 2.40 (P < 0.01). On the eighth day the extent of pathological changes were milder in the lidocaine group than that in the control group. The elimination half life of lidocaine was 40.44 +/- 7.99 during hypothermia and 2.01 +/- 4.56 during rewarming. CONCLUSIONS: In dogs lidocaine prolongs the safe duration of circulatory arrest during hypothermia.

Anesthetics, Local↗

PubMed1998

Expression of beta3-adrenoceptors in rat detrusor smooth muscle.

PURPOSE: To investigate the expression of beta-adrenoceptor (AR) subtypes responsible for detrusor smooth muscle relaxation. MATERIALS AND METHODS: Isolated rat detrusor smooth muscle was examined by tension measurement and reverse transcription polymerase chain reaction (RT-PCR). RESULTS: Norepinephrine (NE), epinephrine (EP) and isoproterenol (ISO) were found to relax the detrusor muscle pre-contracted by 6 x 10(-7) M carbachol in the presence of 10(-6) M phentolamine. NE relaxed the detrusor muscle as potently as EP. This potency order (NE=EP) thus indicated the beta-ARs of the rat detrusor muscle to possibly be a beta1 subtype. However, in the presence of 10(-6) M propranolol, beta1- and beta2- but not beta3-AR antagonist, NE showed a more potent relaxation than EP. This observation indicated that the rat detrusor muscle also possesses beta3-AR. RT-PCR revealed all three subtypes of beta-AR mRNA, namely beta1-, beta2- and beta3-AR mRNA, to be expressed in rat detrusor smooth muscle cells. CONCLUSION: We concluded that beta3-ARs exist in rat detrusor smooth muscle based on both pharmacological and molecular biological studies. Based on these findings, beta-ARs of rat detrusor smooth muscle are considered to be mixed populations consisting of three subtypes which play an important role in relaxing smooth muscle in response to catecholamines.

Animals↗

PubMed1998

Unique wave front for dendritic spines with Nagumo dynamics.

A model of dendritic spines uniformly distributed along a dendrite cable with the Nagumo dynamics for active membrane spine activity is considered. We show analytically the existence and uniqueness of traveling front solutions for a wide range of parameters including the spine density and the resistance between spine heads and dendrites. And such wave front travels at a slower speed for a larger spine density. Numerical simulations support the above results.

Dendrites↗

PubMed1998

Structure of a snake venom phospholipase A2 modified by p-bromo-phenacyl-bromide.

The crystal structure of acidic phospholipase A2 (APLA2) from Agkistrodon halys pallas covalently modified by p-bromo-phenacyl-bromide (pBPB) was determined to a resolution of 2.0 A by an isomorphous difference Fourier method with the native APLA2 structure as an initial model and refined to a crystallographic R factor of 15.3%. The modified APLA2 structure is remarkably similar to that of the native one. Least-squares superposition of C alpha atoms of native and modified APLA2 results in a root-mean-square coordinate deviation of 0.243 A. The p-bromo-phenacyl group near the active site occupies a position similar to that in pBPB modified bovine pancreatic PLA2. The inhibitor covalently bound to the NDI atom of His48 fits well in the hydrophobic channel, forming extensive hydrophobic interactions with the surrounding residues, especially with the side chains of Phe5 and Cys45 and the main chain of Gly30. However, the inhibitor does not change the conformation of these residues except that Trp31 at the entrance of the hydrophobic channel moves slightly toward the inhibitor. Compared with native APLA2, the Ca2+-binding loop shows a little conformational change and a cation, probably Na+, occupies in the position of Ca2+. The binding of pBPB to APLA2 induce no other significant conformational changes in the enzyme molecule elsewhere.

Acetophenones↗

PubMed1998

Effects of "binge" pattern cocaine on stereotypy and locomotor activity in C57BL/6J and 129/J mice.

This study characterized the behavioral response to cocaine in two strains of mice, the C57BL/6J and 129/J strains, commonly utilized as host strains for transgenic and "knockout" mice. The psychomotor stimulating effects of four doses of cocaine (2.5, 5.0, 10.0, and 15.0 mg/kg/injection) with a saline control, administered in a "binge" pattern (three equal injections at hourly intervals) for 3 days were examined in adult male C57BL/6J and 129/J mice. Behavioral stereotypy in the home cage, was rated 15, 30, and 45 min following each injection. Spontaneous locomotor activity in the home cage was also monitored. Cocaine, at doses of 10.0 or 15.0 mg/kg, produced behavioral stereotypy in both C57BL/6J mice (p < 0.0001) and 129/J mice (p < 0.0001), whereas lower doses did not. The magnitude of stereotypy was significantly lower in 129/J mice than in C57BL/6J mice receiving identical doses of cocaine. C57BL/6J mice also demonstrated a dose-dependent cocaine-induced stimulation of locomotor activity following administration of 10.0 or 15.0 mg/kg of cocaine (p < 0.0005). In contrast, 129/J mice did not exhibit increased locomotion in response to any dose of cocaine tested. These results demonstrate that strain differences in drug-induced behavior may be more pronounced in one measure (i.e., locomotor activity) than in another (i.e., stereotypy) and indicate the importance of multiple behavioral measures.

Animals↗