Biomedical subjects

Hua Xu

Publications and source records attributed to Hua Xu.

At least 37 records · Page 2Linked to original sources

PubMed2005

Subcloning, localization, and expression of the rat intestinal sodium-hydrogen exchanger isoform 8.

Apically expressed intestinal and renal sodium-hydrogen exchangers (NHEs) play a major role in Na(+) absorption. Our previous studies on NHE ontogeny have shown that NHE-2 and NHE-3 are expressed at very low levels in young animals. Furthermore, single and/or double NHE-2 and NHE-3 knockout mice display no obvious abnormalities before weaning. These observations suggest that other transporter(s) may be involved in intestinal Na+ absorption during early life. The present studies were designed to clone the novel rat intestinal NHE-8 cDNA and to decipher the NHE-8 protein localization and gene expression pattern during different developmental stages. The rat NHE-8 cDNA has 2,160 bp and encodes a 575-amino acid protein. An antibody against NHE-8 protein was developed. Immunohistochemistry staining indicated apical localization of NHE-8 protein in rat intestinal epithelial cells. The apical localization of NHE-8 was also confirmed by its presence in brush-border membrane and its absence in basolateral membrane preparations. Northern blotting utilizing a NHE-8-specific probe demonstrated higher NHE-8 mRNA expression in young animals compared with adult animals. Western blot analysis revealed a similar pattern. Tissue distribution with multiple human tissue RNA blot showed that NHE-8 was expressed in multiple tissues including the gastrointestinal tract. In conclusion, we have cloned the full-length NHE-8 cDNA from rat intestine and further showed its apical localization in intestinal epithelial cells. We have also shown that NHE-8 gene expression and protein expression were regulated during ontogeny. Our data suggests that NHE-8 may play an important role in intestinal Na+ absorption during early life.

Amino Acid Sequence↗

PubMed2005

ER Ca2+ depletion triggers apoptotic signals for endoplasmic reticulum (ER) overload response induced by overexpressed reticulon 3 (RTN3/HAP).

Perturbance of endoplasmic reticulum (ER) function, either by the mutant proteins not folding correctly, or by an excessive accumulation of proteins in the organelle, will lead to the unfolded protein response (UPR) or ER overload response (EOR). The signal-transducing pathways for UPR have been identified, whereas the pathway for EOR remains to be elucidated. Our previous study demonstrated that the overexpression of reticulon 3 (RTN3, also named HAP, homologue of ASY protein) caused apoptosis with the depletion of ER Ca(2+) stores. In present research, we characterized RTN3 as a novel EOR-induced protein, triggering the apoptotic signals through the release of ER Ca(2+) and the elevation of cytosolic Ca(2+). Our studies showed that overexpressed RTN3 induced EOR, eliciting ER-specific apoptosis with activation of caspase-12 and mitochondrial dysfunction through ER Ca(2+) depletion and the sustained elevation of cytosolic Ca(2+). Furthermore, we demonstrated that overexpressed RTN3 and stimuli that activate both EOR and UPR, not UPR only, were able to induce up-regulation of inducible nitric oxide synthase (iNOS) in HeLa cells through ER Ca(2+) release and reactive oxygen intermediates (ROIs), resulting in endogenous calcium-dependent nitric oxide protecting cells against ER specific apoptosis, which suggested that the nitric oxide and iNOS represented a likely protective response to EOR, not the UPR. These results supported that the release of ER Ca(2+) stores triggered the initial signal-transducing pathways for EOR induced by overexpressed RTN3.

Animals↗

PubMed2005

The function of envelope protein P74 from Autographa californica multiple nucleopolyhedrovirus in primary infection to host.

This research investigated the function of envelope protein P74 of Autographa californica multiple nuclear polyhedrosis virus (AcMNPV) in primary infection to host. A p74-inactivation recombinant baculovirus, rAc-gfp(Delta) p74, was constructed by inserting gfp driven by AcMNPV polyhedrin promoter into the p74 locus of AcMNPV genome. Bioassays showed that the P74-null occlusion bodies (OBs) failed to infect its natural host larvae, Spodoptera exigua, per os, while the p74-null budded virus (BVs) could infect host larvae by injection. However, its inability for oral infectivity was rescued by a mixed infection with wild-type OBs or with the purified P74 protein expressed in Spodoptera frugiperda Sf-9 cells, and the P74 protein rescue was in a dosage-dependent manner. The 50% lethal dosage (LD50) value of a P74 overexpression recombinant virus, rAc-p74(++)-polh+, which contained two copies of p74 gene, was not significantly different from that of wild-type virus. One-step growth curve assays of viruses suggested that BV production from cells infected with p74-null virus was similar to that from cells infected with wild-type virus or the P74 overexpression virus. ELISA analysis indicated that P74 protein could bind its host brush border membrane vesicles (BBMV) efficiently with saturation, but it could only bind its sensitive midgut BBMV specifically. In vitro pull-down assay showed that a protein of approximately 35 kDa in the BBMV was involved in the specific binding. These results demonstrated that the P74 protein is essential for oral infectivity of occlusion-derived virus (ODV) and plays a role in midgut attachment and fusion.

Animals↗

PubMed2005

Expression and purification of soluble non-fusion vasostatin in Escherichia coli.

Vasostatin has previously been expressed in fused form or in inclusion body form in Escherichia coli. Here the protein was expressed in soluble non-fusion form in BL21(DE3)pLysS by IPTG induction. The expression level of vasostatin was about 15% of the total cellular protein. The expressed vasostatin was purified and its biological activity was investigated by an endothelial cell proliferation assay.

Calreticulin↗

PubMed2005

Photosensitive precursors to nitric oxide.

The photochemistry and use of recently developed photosensitive precursors to nitric oxide (NO) are reviewed. As "caged NO" donors these precursors are able to deliver NO in a spatially and temporally controllable manner. These properties have made such precursors useful in applications in biology and medicine, especially in elucidating neurophysiological roles of NO and in new cancer therapies.

Animals↗

PubMed2005

[Protective effect of non-mitogenic haFGF on retinal injury induced by N-methyl-N-nitrosourea in Sprague-Dawley rats].

AIM: To study the effect of non-mitogenic human acidic fibroblast growth factor (nm-haFGF) on retinal injury induced by N-methyl-N-nitrosourea (MNU) in Sprague-Dawley rats and its mechanism. METHODS: Female rats of 50-days-old were injected with MNU (60 mg x kg(-1)) intraperitoneally, and three doses of nm-haFGF (1.25 microg, 2.5 microg and 5 microg in one eye of each rat) were injected, separately, into vitreous body of one eye of each rat twice a day at 0 and 12 h after MNU treatment. 24 h later, apoptotic index of photoreceptor cells was detected by TUNEL labeling and the expressions of Bcl-2 and Bax were analyzed by Western blotting. At the 7th day, retinal injury was evaluated based on retinal thickness. RESULTS: Compared with model group, apoptotic index of photoreceptor cells was significantly reduced in nm-haFGF groups at the dose of 1.25 microg and 2.5 microg in one eye of each rat at 24 h, and the total retinal thickness as well as the outer retinal thickness markedly increased 7 days after MNU, respectively. The expressions of Bcl-2 increased and that of Bax decreased adversely after being injected with different doses of nm-haFGF. CONCLUSION: nm-haFGF partially suppressed retinal injury induced by MNU in Sprague-Dawley rats. The mechanism could be related to up-regulation of Bcl-2 and down-regulation of Bax.

Animals↗

PubMed2005

[Cloning, purification, and antigenic characterization of three recombinant fragments derived from SARS-CoV S1 domain].

OBJECTIVE: The present study aimed to clone and express three fragments of genomic RNA derived from SARS associated coronavirus (SARS-CoV) S1 domain and to study its immunogenicity. METHODS: The S1 domain gene was amplified by PCR with specific primers and was inserted into the prokaryotic expression vector pQE-30. Three fragments (40-751, 746-1344 and 746-2001 bp) derived from S1 domain produced after the recombinant plasmid (pQE-30/S1) was digested by restriction endonucleases. The three fragments were cloned into pQE-30 and expressed in M15 strains of Escherichia coli. The expression products, designated S1a, S1b and S1c respectively, were purified by Ni affinity chromatography. The immunogenicity was analyzed by Western Blot and ELISA using serologically confirmed sera from SARS patients and the sera from healthy donors was used as control at the same assay. RESULTS: Three recombinant plasmids (pQE-30/S1a, pQE-30/S1b, pQE-30/S1c) were constructed.Fusion proteins with relative molecular mass of 26,700, 22,500 and 46,000 dalton were successfully expressed with amounts of 35%, 35% and 30% of total cell protein and purified by Ni affinity chromatography, respectively. Western Blot and ELISA analysis showed that the S1c protein could be specifically recognized by the sera from SARS patients. CONCLUSION: The recombinant S1c protein was a good immunogen and has the potential to be used as a vaccine against SARS-CoV infection.

Antibodies, Viral↗

PubMed2005

[The effects of dietetic hyperlipidemia on the development of testes and penises in male New Zealand rabbits].

OBJECTIVE: To study the effects of dietetic hyperlipidemia on the development of testes and penises in male New Zealand rabbits. METHODS: The animal model of dietetic hyperlipidemia was established by feeding 36 male New Zealand rabbits which were divided into the test group (n = 20) and the control group (n = 16) at random with rich fat. The concentration of TC, TG, HDL-C as well as LDL-C was determined by using automatic biochemistry analyzer. Radioimmunoassay methods were used to measure the level of T, LH and FSH as well. Alterations of testicular and penial development in morphology were observed by HE staining. RESULTS: Compared with the control group, concentrations of TC, TG and LDL-C increased dramatically as well as the levels of T, LH and FSH decreased obviously. There are significant differences between the two groups (P <0.01). Compared with the control group, the penial length was short (P < 0.05) and testicular coefficient declined (P < 0.01) in the test group. With light microscope, the following phenomenon was manifestly detected: the sabotage of spermatogenic epithelium and the adipocyte sedimentation of the penial tissue. CONCLUSION: It is obvious that intaking a large quantity of food with rich fat from juvenile would induce dietetic hyperlipidemia, result in the functional disorder of hypothalamo-pituitary-gonadal axis, and leads to short penis in development and the damage of spermatogenesis function as well.

Animal Feed↗

PubMed2004

ORF390 of white spot syndrome virus genome is identified as a novel anti-apoptosis gene.

Apoptosis serves as an important defense strategy employed by host cells against viral invasion. Many viruses contain the anti-apoptotic genes to block the defense-by-death response of host cells. In this study, we tried to identify the putative anti-apoptotic genes in white spot syndrome virus (WSSV) genome. We confirmed that actinomycin D could induce apoptosis of shrimp primary cells. However, the apoptosis triggered by actinomycin D was inhibited by WSSV infection. As mutants of Autographa californica nucleopolyhedrovirus (AcMNPV), AcMNPVDelta35k/pol+ lacks a functional P35 gene undergoing apoptosis and its infection could induce Sf9 cell apoptosis. To identify the putative apoptotic suppressor gene of WSSV, overlapping cosmid clones representing the entire WSSV genome were individually cotransfected along with genome DNA of AcMNPVDeltaP35k/pol+. Using this marker rescue assay, a WSSV DNA fragment that was able to rescue AcMNPVDeltaP35k/pol+ infection in Sf9 cells was isolated. By further sequence analysis and rescue assay, the ORF390 was identified as a novel anti-apoptotic gene. The ORF displays two putative caspase9 cleavage sites LLVETDGPS, VKLEHDGSK, and a caspase3 cleavage site EEDEVDGVP. The ORF was cloned into the pIE1 vector and then the recombinant vector was transfected into Sf9 cells. The Sf9 cells did not show obvious characteristics of apoptosis when infected with AcMNPVDeltaP35k/pol+. And the transient expression of ORF390 allowed AcMNPVDeltaP35k/pol+ replication in Sf9 cells and resulted in the formation of polyhedra successfully. The results indicate that function of ORF390 in WSSV is a kind of apoptotic suppressor like P35 in AcMNPV.

Amino Acid Sequence↗

PubMed2004

[Multicenter, randomized, positive-controlled clinical study for the effects of nerotropin on diabetic neuropathy].

OBJECTIVE: To estimate the effects of Neurotropin in the treatment of neuralgia and numbness in type 2 diabetes mellitus patients with diabetic peripheral neuropathy (DPN), and compare with Methycobal. METHODS: Ninety-five patients with DPN from 4 hospitals in shanghai were randomly assigned to two groups: 49 cases in Neurotropin group (6 ml, IV, QD for 2 weeks, then, 2 tablets, BID for another 2 weeks). 46 cases in Methycobal group (1 ml, IM, QD for 2 weeks, then, 1 tablet TID for another 2 weeks. RESULTS: Neurotropin significantly improved neuralgia in type 2 diabetes mellitus with DPN, the efficacy rate was 67.3% in the first week, and 87.0% in the 4th week, comparing with 34.8% and 68.5% in the control group. The efficacy rate for numbness was 58.7% in the study group after 4 weeks therapy, and 69.5% in control group. In the whole 4 weeks therapeutic course, neuralgia and numbness were improved in the two groups, and the improved rate in Neurotropin group is high than in the control group (P < 0.01). CONCLUSION: Neurotropin had good effects in the treatment of diabetic neuralgia and numbness, the efficacy of Neurotropin in improving the senses of neuralgia is better than Methecobal., and similar with Methecobal in treating numbness.

Aged↗

PubMed2004

NF1 transcriptional factor(s) is required for basal promoter activation of the human intestinal NaPi-IIb cotransporter gene.

The human intestinal type IIb Na+-P(i) cotransporter (hNaPi-IIb) gene promoter lacks a TATA box and has a high GC content in the 5'-flanking region. To understand the mechanism of hNaPi-IIb gene transcription, the current study was performed to characterize the minimal promoter region and transcriptional factor(s) necessary to activate gene expression in human intestinal cells (Caco-2). With the use of progressively shorter promoter constructs, a minimal promoter extending from bp -58 to +15 was identified and shown to direct high levels of hNaPi-IIb cotransporter expression in Caco-2 cells. Gel mobility shift assays (GMSAs) indicated that two regions could be bound by nuclear proteins from Caco-2 cells: region A at bp -26/-23 and region B at bp -44/-35. The introduction of mutations in region A abolished promoter activity, whereas mutations in region B had no effect. Deletion mutants of the same regions showed identical results. Furthermore, DNase I footprinting experiments confirmed the observation made by GMSAs. Additional studies, which used a specific nuclear factor 1 (NF1) antiserum, demonstrated that NF1 protein(s) binds to the minimal promoter at region A. These results indicated that the NF1 protein(s) is required to activate the basal transcription of hNaPi-IIb gene under normal growth conditions. This study has thus identified a new target gene in the small intestinal epithelium that is directly regulated by NF1 transcriptional factor(s).

Base Sequence↗

PubMed2004

Controlled photochemical release of nitric oxide from O2-substituted diazeniumdiolates.

Diazeniumdiolates are a well-established class of nitric oxide (NO) donors that have been employed in a wide variety of biochemical and pharmacological investigations. To provide a means of targeting NO release, photosensitive precursors to diazeniumdiolates have been developed and are reviewed here. After a brief description of diazeniumdiolate chemistry and the potential uses of photosensitive precursors to NO, three different classes of phototriggered diazeniumdiolates are discussed: 2-nitrobenzyl derivatives, meta-substituted benzyl derivatives, and naphthylmethyl and naphthylallyl derivatives. In addition, the photochemistry of diazeniumdiolate salts themselves is covered.

Animals↗

PubMed2004

The Heliothis armigera single nucleocapsid nucleopolyhedrovirus envelope protein P74 is required for infection of the host midgut.

In order to study the function of the envelope protein P74 of Heliothis armigera single nucleocapsid nucleopolyhedrovirus (HaSNPV), a p74-null recombinant baculovirus, rHa-gfdeltap74, was constructed by inserting gfp driven by the polyhedrin promoter into the p74 locus of HaSNPV genome. The resulting p74-inactivation occlusion-derived viruses (ODV) failed to infect its natural host larvae per os. However, its inability of oral infectivity was rescued using the purified P74 protein expressed by Bac-to-Bac system in Hz-AM1 cells. Feeding the purified P74 protein along with the p74 deletion mutant virus rHa-gfpdeltap74 to H. armigera larvae resulted in the rescue of oral infectivity in a dose dependent manner. The P74 protein was expressed in-frame with GFP to create a P74-GFP chimera for studying the localization of P74, the GFP portion of the chimera facilitating the visualization of the trafficking of P74 in cells. The P74-GFP chimeric proteins localized in the intranuclear ring zone and accumulated into microvesicles. In addition, the specific and saturable binding of P74 protein to its host brush border membrane vesicles (BBMVs) was involved in the invasion of virus. Further investigations (pull-down assay) showed that an about 30 kDa protein in the BBMVs was involved in the specific binding. These results demonstrated that the P74 protein is essential for oral infectivity of ODV and plays a role in midgut attachment and fusion.

Administration, Oral↗

PubMed2004

Effect of angiotensin-II on renal Na+/H+ exchanger-NHE3 and NHE2.

The purpose of the present study was to determine the effect of angiotensin II (A-II) on membrane expression of Na+/H+ exchange isoforms NHE3 and NHE2 in the rat renal cortex. A-II (500 ng/kg per min) was chronically infused into the Sprague-Dawley rats by miniosmotic pump for 7 days. Arterial pressure and circulating plasma A-II level were significantly increased in A-II rats as compared to control rats. pH-dependent uptake of 22Na+ study in the presence of 50 microM HOE-694 revealed that Na+ uptake mediated by NHE3 was increased approximately 88% in the brush border membrane from renal cortex of A-II-treated rats. Western blotting showed that A-II increased NHE3 immunoreactive protein levels in the brush border membrane of the proximal tubules by 31%. Northern blotting revealed that A-II increased NHE3 mRNA abundance in the renal cortex by 42%. A-II treatment did not alter brush border NHE2 protein abundance in the renal proximal tubules. In conclusion, chronic A-II treatment increases NHE3-mediated Na+ uptake by stimulating NHE3 mRNA and protein content.

Angiotensin II↗

PubMed2004

Flexible alteration of optical nonlinearities of iodine charge-transfer complexes in solutions.

The type of donor used is found to influence greatly the optical nonlinearities of iodine charge-transfer (CT) complexes in solutions for several solvents. The magnitude and sign changes of nonlinear absorption of iodine CT complexes for different solvents as donors are observed, which implies the transition from saturable absorption to reverse saturable absorption. Compared with C60 in toluene, iodine CT complexes with toluene and benzene demonstrate larger reverse saturable absorption. Meanwhile, flexible alteration of optical nonlinearities is easily obtained by adjusting the mixture ratio of different solvents, yielding a prospective means of constructing a nonlinear medium with a large nonlinear coefficient.

Journal Article↗

PubMed2004

In situ TA-MS study of the six-membered-ring-based growth of carbon nanotubes with benzene precursor.

By using the in situ thermal analysis-mass spectroscopic technique, combined with transmission electron microscopic characterization of the carbon nanotube (CNT) product, we have studied the chemical vapor deposition (CVD) growth of CNTs with Fe-Co/gamma-Al2O3 catalyst and benzene precursor in the range of room temperature to 700 degrees C. The growth process has been clearly illuminated, which starts from the reduction of catalyst around 645 degrees C followed by the dissociation of carbon-hydrogen bonds of benzene and the sequential growth of CNTs. A surprising fact is that no possible hydrocarbon species derived from benzene was detected, indicating that the carbon-carbon bond was not broken under our experimental conditions. All of the experimental results strongly reinforce the six-membered-ring-based growth model, and a schematic elucidation is presented accordingly. This in situ study not only reveals the unique and convincing information directly related to the growth mechanism from the involved chemistry, but also provides a powerful way to clarify the mechanism of CVD synthesis of CNTs with other precursors.

Journal Article↗

PubMed2004

[Preliminary in vitro study on modification of RBC with mPEG-BTC for resolving the problem of clinical difficulty in blood matching].

The aim of this study was to find an effective solution for difficulty of blood matching. Twenty nine cases with clinical difficult in blood matching were collected, classified by their etiological factors, and analyzed with all the antibodies in serum. RBC from health donor were incubated with mPEG-BTC at 25 degrees C for 1 hour. The coagulation of patient serum and donor RBC before and after mPEG-BTC camouflage was detected and compared by polybrene and antihuman globulin reagents. The result showed that 29 cases with difficult blood matching mainly suffered form blood diseases and tumors. The main antibody were Rh and autoantibody. Donor RBC modified by mPEG showed no coagulation with the blood serum in the patients with problems of blood matching. In conclusion, the modification of RBC with mPEG-BTC provides a useful strategy for resolving problem of clinical difficulty in blood matching.

Adolescent↗

PubMed2004

[Immunological characteristics of 1291 cases of severe acute respiratory syndrome in Beijing].

OBJECTIVE: To investigate the immunological characteristics of the cases of severe acute respiratory syndrome (SARS) in Beijing City. METHODS: Clinical data of 1291 patients with SARS from March to July 2003 in Beijing City were retrospectively analyzed. RESULTS: In patients with SARS, the absolute numbers of white blood cells, lymphocytes and CD(3), CD(4) and CD(8) lymphocyte subsets decreased during the early period of the disease, being manifested in 56.91%, 88.26%, 47.96%, 45.56% and 41.10% of the patients, respectively. During the first 3 days the median numbers of CD(3), CD(4) and CD(8) were 425 x 10(6)/L, 223 x 10(6)/L, 170 x 10(6)/L, respectively, being the lowest values in the course of the disease. During the second week the corresponding numbers were 536 x 10(6)/L, 267 x 10(6)/L, 224 x 10(6)/L, respectively; they returned to normal by the fourth week (P < 0.05), showing a trend of gradual increase during the disease progression. Comparison of different time points of the same cases also showed that CD(3), CD(4) and CD(8) were lowest in the first 1 - 3 days. The median number of CD(3) was higher (954 x 10(6)/L) during week 3, and there was no significant difference among other 3 weeks (P > 0.05). In the early period of the disease the CRP increased but ESR, C(3) and C(4) were still in normal ranges. CONCLUSIONS: In the early period of SARS, the WBC, lymphocytes, CD(3), CD(4) and CD(8) lymphocyte subsets decreased remarkably, and they tended to increase as the disease progressed. Simultaneous decreases in CD(3), CD(4) and CD(8) during the first week is a characteristic immunological change, which may facilitate the early diagnosis of SARS.

Adolescent↗