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Biomedical subjects

W Gu

Publications and source records attributed to W Gu.

At least 37 records · Page 2Linked to original sources
PubMed2001

Vascular endothelial growth factor-A and -C protein up-regulation and early angiogenesis in a rat photothrombotic ring stroke model with spontaneous reperfusion.

This study explored the temporal expression pattern of two subtypes of vascular endothelial growth factor (VEGF) proteins and three subforms of their receptors as well as endothelial proliferation in adult rats subjected to photothrombotic ring stroke with spontaneous reperfusion in the cortical region at risk. The exposed crania of halothane-anesthetized, temperature- and blood gas-controlled male Wistar rats were irradiated with a ring laser beam started simultaneously with systemic injection of the photosensitizer erythrosin B. Rats were repeatedly injected with 5-bromodeoxyuridine (BrdU) after stroke induction. Immunohistochemistry of coronal brain sections showed that VEGF protein subtype C increased simultaneously with subtype A in the ring lesion region at 2 h after irradiation. In the cortical region at risk (i.e., the penumbra-like zone), increased VEGF-C and VEGF-A immunostaining was seen at 24 h with sustained appearance up to 72 h after ischemic onset. Correspondingly, the VEGF-C-specific receptor flt-4 and the VEGF-A receptors flt-1 and flk-1 were up-regulated in a temporal sequence similar to that of their agonist proteins in the cortical ring lesion and the region at risk. At 48 h after stroke induction, proliferating BrdU-immunopositive endothelial cells formed microvessels in the post-ischemic cortical region at risk. These vessels became more pronounced at 72 h and were still visible at 100 days after the stroke. This study suggests that VEGF-C and its receptor flt-4 may cooperate with VEGF-A and its receptors flt-1 and flk-1 to promote early angiogenesis after stroke, which may in turn contribute to spontaneous reperfusion in this focal thromboembolic stroke model.

Animals↗
PubMed2001

Progressive and reproducible focal cortical ischemia with or without late spontaneous reperfusion generated by a ring-shaped, laser-driven photothrombotic lesion in rats.

Clinical stroke is mostly of thromboembolic origin, in which the magnitude of brain damage resulting from arterial occlusions depends on the degree and duration of the concomitant ischemia. To facilitate more controllable and reproducible study of stroke-related pathophysiological mechanisms, a photothrombotic ring stroke model was initially developed in adult rats. The ring interior zone comprises an anatomically well confined cortical region-at-risk which is gradually encroached by progressive hypoperfusion, thus mimicking the situation (albeit in inverse fashion) of an ischemic penumbra or stroke-in-evolution. Modification of this model using a thinner ring irradiation beam resulted in late spontaneous reperfusion in the cortical region-at-risk and a remarkable morphological tissue recovery in this ostensibly critically injured region. On the other hand, doubling the thin irradiating beam intensity facilitates a complementary situation in which lack of reperfusion in the region-at-risk after stroke induction leads to tissue pannecrosis. The dual photothrombotic ring stroke model, effectuated either with or without reperfusion and thereby tissue recovery or pannecrosis, may be well suited for the study of events related to postischemic survival or cell death in the penumbra region. To popularize the photothrombotic ring stroke model, we present a detailed protocol of how this model is induced in either version as well as protocols for transcardial carbon black perfusion and laser-Doppler flowmetry experiments.

Animals↗
PubMed2001

Genetic variation in bone-regenerative capacity among inbred strains of mice.

Genetic variation in bone-regenerative capacity has not been studied in any animal model system. We developed a "drill-hole" model in the tail vertebra of inbred strains of mice that allows us to reproducibly introduce an injury with a defined boundary and quantify the rate of bone healing using the combination of high-resolution Faxitron X-ray imaging and the ChemiImager 4000 Low Light Imaging System. Using this model, we demonstrate that bone-regenerative capacity is a genetically controlled trait with an estimated heritability of 72%, and that it differs significantly among inbred strains of mice. Of the 12 inbred strains tested, Sencar/PtJ was identified as the most suitable model for the study of hard-tissue regeneration. This strain regained 73% of bone loss 30 days after injury, in contrast to the slow healer, CBA/J, which recovered only 25% of the bone loss during the same period. Bone-regenerative capacity was not correlated with soft-tissue-regenerative capacity, suggesting that different sets of genes may regulate soft- and hard-tissue regeneration. It was, however, significantly correlated with total bone mineral density (R = 0.49, p < 0.01), indicating that high bone density is associated not only with prevention of bone fracture, but also with promotion of bone regeneration.

Animals↗
PubMed2001

Polymerized lyotropic liquid crystal assemblies for materials applications.

The development of functional materials with nanometer-scale architectures and the effect of these architectures on their chemical and physical properties are currently of great interest in materials design. Polymerizable lyotropic liquid crystal (LLC) assemblies provide a facile entry into this area by allowing one to fix the inherent order in these systems using covalent bonds to create robust, nanostructured materials. The use of the cross-linked inverted hexagonal phase in templated nanocomposite formation and heterogeneous catalysis has been demonstrated. Additionally, the polymerization of LLC mesogens in the regular hexagonal and bicontinuous cubic phases is being targeted for future developments in functional materials. Future directions for new applications of these materials are also discussed.

Journal Article↗
PubMed2001

Genetic control of the rate of wound healing in mice.

There have been few studies of the inheritance of wound healing in mammals. In this study, we demonstrate that inbred strains of mice differ significantly in the rate of wound healing. Of the 20 strains tested, fast healers (MRL/MpJ-Fas(lpr) and LG/J) healed wounds four times faster than slow healers (Balb/cByJ and SJL/J). The genetic basis underlying the difference in the healing capacity was analysed using F2 populations of two different crosses. We show that the wound healing is a polygenically determined quantitative trait with an average estimated heritability of 86%. The modes of gene action in these two crosses are different. In the (MRL/MpJ x SJL/J) cross, genes regulating fast healing in MRL/MpJ mice exhibited additive effects, whereas these effects were suppressed by a dominant repressor gene in CBA/J mice in the (MRL/MpJ-Fas(lpr) x CBA/J) cross. Information gained from this investigation provides insight into further study of molecular mechanisms underlying the rate of wound healing in mammals.

Analysis of Variance↗
PubMed2001

Identification of wound healing/regeneration quantitative trait loci (QTL) at multiple time points that explain seventy percent of variance in (MRL/MpJ and SJL/J) mice F2 population.

Studies on genetic mechanisms of wound healing in mammals are very few, although injury is a leading cause of the global burden of disease. In this study, we performed a high-density, genome-wide scan using 633 (MRL/MPJ x SJL/J) F(2) intercross at multiple time points (days 15, 21, and 25) to identify quantitative trait loci (QTL) involved in wound healing/regeneration. The hypothesis of the study was that QTL and unique epistatic interactions are involved at each time point to promote wound healing/regeneration. Ten QTL were identified from chromosomes 1, 4, 6, 7, 9, and 13. Of the 10 QTL, eight from chromosomes 1, 4, 6, and 9 were novel as compared to QTL identified in the study. The 10 QTL altogether explained 70% of variance in F(2) mice. The same QTL were identified at each time point, with simple linear correlation between days 15, 21, and 25, showing very high significant relationships (R >0.92, P <0.0001). Unique epistatic interactions were identified at each time point except those from chromosomes 4, 6, 9, and 13 that were found at all three time points, showing that some loci are involved at all the three time points of wound healing (days 15, 21, and 25). Therefore, loci-to-loci interactions may play a major role in wound healing. Information from these studies may help in the identification of genes that could be involved in wound healing/regeneration.

Analysis of Variance↗
PubMed2001

Detection of sporadic cases of hepatitis E virus (HEV) infection in China using immunoassays based on recombinant open reading frame 2 and 3 polypeptides from HEV genotype 4.

We reported previously on the complete sequence of hepatitis E virus (HEV) genotype 4, isolated from patients with sporadic cases of acute HEV infection in China. At least eight HEV genotypes have now been described worldwide, and further isolates await classification. Current immunoassays for the detection of anti-HEV antibodies are based on polypeptides from genotypes 1 and 2 only and may be inadequate for the reliable detection of other genotypes. Because genotypes 1 and 4 predominate in China, we wished to investigate the antigenic reactivities of HEV genotype 4 proteins. Four overlapping regions of open reading frame 2 (ORF2) (FB5, amino acids [aa] 1 to 130; E4, aa 67 to 308; F2-2, aa 288 to 461; E5, aa 414 to 672) and the entire ORF3 product were expressed in Escherichia coli as fusion proteins. Enzyme immunoassays based on each of the five purified polypeptides were evaluated with sera from patients with sporadic cases of acute HEV infection. Individual immunoassays derived from HEV genotype 4 detected more cases of acute hepatitis E than a commercial assay. Some serum samples, which were positive for anti-HEV immunoglobulin G only by assays based on HEV genotype 4, were positive for HEV RNA by reverse transcription-PCR. Polypeptide FB5, from the N terminus of ORF2, had the greatest immunoreactivity with sera from patients with acute hepatitis E. These data indicate that the N terminus of ORF2 may provide epitopes which are highly reactive with acute-phase sera and that assays based on genotypes 1 and 2 alone may be inadequate for the detection of HEV infection in China, where sporadic cases of HEV infection are caused predominantly by HEV genotypes 4 and 1.

Acute Disease↗
PubMed2001

Cortical neurogenesis in adult rats after transient middle cerebral artery occlusion.

BACKGROUND AND PURPOSE: This study explored the possible occurrence of newly generated nerve cells in the ischemic cortex of adult rats after middle cerebral artery occlusion and reperfusion. METHODS: Nine- to 10-week-old male Wistar rats were subjected to 2 hours of middle cerebral artery occlusion by the monofilament method. Rats received repeated intraperitoneal injections of the cell proliferation-specific marker 5-bromodeoxyuridine (BrdU) after stroke induction. Brain sections were processed for immunohistochemistry with an avidin-biotin complex-alkaline phosphatase and/or -peroxidase method. Brain sections processed with double-immunofluorescent staining were further scanned by confocal microscopy. RESULTS: Interspersed among the predominantly newly formed glial cells, some cells were double labeled by BrdU and 1 of the neuron-specific markers, Map-2, beta-tubulin III, and Neu N, at 30 and 60 days after stroke onset. These cells were randomly distributed throughout cortical layers II through VI, occurring with highest density in the ischemic boundary zone. Three-dimensional confocal analyses of BrdU and the neuron-specific marker Neu N confirmed their colocalization within the same cortical cells. CONCLUSIONS: This study suggests that new neurons can be generated in the cerebral cortex of adult rats after transient focal cerebral ischemia. Cortical neurogenesis may be a potential pathway for brain repair after stroke.

Animals↗
PubMed2001

[Relationship between circulating vascular cell adhesion molecule-1 and vascular complications in type 2 diabetes mellitus].

OBJECTIVE: To investigate the relationship between soluble vascular cell adhesion molecule-1 (sVCAM-1) and type 2 diabetes complicated with vascular diseases. METHODS: In 61 cases of type 2 diabetes with macrovascular or microvascular complications and 36 cases of healthy control, sVCAM-1 levels were measured in duplicate by enzyme-linked immunosorbent assay using the soluble VCAM-1 Kit (R& D Systems Ltd, Ablingdon, Oxfordshire, UK). RESULTS: sVCAM-1 levels in type 2 diabetes [(973.25 +/- 73.38) microg/L] were higher than these of healthy controls [(230.45 +/- 12.47) microg/L], P < 0.001. sVCAM-1 levels of type 2 diabetes with hypertension [(1263.99 +/- 87.00) microg/L] were higher than those of type 2 diabetes with microvascular complications [(726.57 +/- 95.40) microg/L], P < 0.001. CONCLUSION: There was a significant correlation between sVCAM-1 concentration and vascular complications of type 2 diabetes.

Aged↗
PubMed2000

Differential protein profile in the ear-punched tissue of regeneration and non-regeneration strains of mice: a novel approach to explore the candidate genes for soft-tissue regeneration.

Wound repair/regeneration is a genetically controlled, complex process. In order to identify candidate genes regulating fast wound repair/regeneration in soft-tissue, the temporal protein profile of the soft-tissue healing process was analyzed in the ear-punched tissue of regeneration strain MRL/MpJ-Fas(lpr) (MRL) mice and non-regeneration strain C57BL/6J(B6) mice using surface-enhanced laser desorption and ionization (SELDI) ProteinChip technology. Five candidate proteins were identified in which responses of MRL to the ear punch were 2-4-fold different compared to that of B6. Their corresponding genes were predicted using an antigen-antibody assay validated mass-based approach. Most of the predicted genes are known to play a role or are likely to play a role in the wound repair/regeneration. Of the five candidate proteins, the amount of the 23560 Da protein in the ear-punched tissue was significantly correlated with the rate of ear healing in six representative strains of mice, making it a good candidate for fast wound repair/regeneration. We speculate that the increased concentration of the 23560 Da protein in the wound tissue could stimulate the expression of various growth-promoting proteins and consequently speed up the wound repair/regeneration processes. Here, we have shown that examination of protein expression profile using SELDI technology, coupled with database search, is an alternative approach to search for candidate genes for wound repair/regeneration. This novel approach can be implemented in a variety of biological applications.

Animals↗
PubMed2000

Differential association of products of alternative transcripts of the candidate tumor suppressor ING1 with the mSin3/HDAC1 transcriptional corepressor complex.

The candidate tumor suppressor ING1 was identified in a genetic screen aimed at isolation of human genes whose expression is suppressed in cancer cells. It may function as a negative growth regulator in the p53 signal transduction pathway. However, its molecular mechanism is not clear. The ING1 locus encodes alternative transcripts of p47(ING1a), p33(ING1b), and p24(ING1c). Here we report differential association of protein products of ING1 with the mSin3 transcriptional corepressor complex. p33(ING1b) associates with Sin3, SAP30, HDAC1, RbAp48, and other proteins, to form large protein complexes, whereas p24(ING1c) does not. The ING1 immune complexes are active in deacetylating core histones in vitro, and p33(ING1b) is functionally associated with HDAC1-mediated transcriptional repression in transfected cells. Our data provide basis for a p33(ING1b)-specific molecular mechanism for the function of the ING1 locus.

3T3 Cells↗
PubMed2000

She2p is a novel RNA-binding protein that recruits the Myo4p-She3p complex to ASH1 mRNA.

In Saccharomyces cerevisiae, Ash1p is a specific repressor of transcription that localizes exclusively to daughter cell nuclei through the asymmetric localization of ASH1 mRNA. This localization requires four cis-acting localization elements located in the ASH1 mRNA, five trans-acting factors, one of which is a myosin, and the actin cytoskeleton. The RNA-binding proteins that interact with these cis-elements remained to be identified. Starting with the 3' most localization element of ASH1 mRNA in the three-hybrid assay, element E3, we isolated a clone corresponding to the C-terminus of She3p. We also found that She3p and She2p interact, and this interaction is essential for the binding of She3p with element E3 in vivo. Moreover, She2p was observed to bind the E3 RNA directly in vitro and each of the ASH1 cis-acting localization elements requires She2p for their localization function. By tethering a She3p-MS2 fusion protein to a reporter RNA containing MS2 binding sites, we observed that She2p is dispensable for She3p-MS2-dependent RNA localization.

Actins↗
PubMed2000

Deacetylation of p53 modulates its effect on cell growth and apoptosis.

The p53 tumour suppressor is a transcriptional factor whose activity is modulated by protein stability and post-translational modifications including acetylation. The mechanism by which acetylated p53 is maintained in vivo remains unclear. Here we show that the deacetylation of p53 is mediated by an histone deacetylase-1 (HDAC1)-containing complex. We have also purified a p53 target protein in the deacetylase complexes (designated PID; but identical to metastasis-associated protein 2 (MTA2)), which has been identified as a component of the NuRD complex. PID specifically interacts with p53 both in vitro and in vivo, and its expression reduces significantly the steady-state levels of acetylated p53. PID expression strongly represses p53-dependent transcriptional activation, and, notably, it modulates p53-mediated cell growth arrest and apoptosis. These results show that deacetylation and functional interactions by the PID/MTA2-associated NuRD complex may represent an important pathway to regulate p53 function.

Acetylation↗
PubMed2000

Targeting the chromatin-remodeling MSL complex of Drosophila to its sites of action on the X chromosome requires both acetyl transferase and ATPase activities.

Dosage compensation in Drosophila is mediated by a multiprotein, RNA-containing complex that associates with the X chromosome at multiple sites. We have investigated the role that the enzymatic activities of two complex components, the histone acetyltransferase activity of MOF and the ATPase activity of MLE, may have in the targeting and association of the complex with the X chromosome. Here we report that MLE and MOF activities are necessary for complexes to access the various X chromosome sites. The role that histone H4 acetylation plays in this process is supported by our observations that MOF overexpression leads to the ectopic association of the complex with autosomal sites.

Acetylation↗
PubMed2000

Molecular and clinical study of spinocerebellar ataxia type 7 in Chinese kindreds.

OBJECTIVE: To investigate the clinical and molecular characteristics of spinocerebellar ataxia type 7 (SCA7) in Chinese kindreds. BACKGROUND: Spinocerebellar ataxia type 7 is caused by the expansion of an unstable CAG repeat in the first exon of the SCA7 gene. METHODS: Clinical and related examinations were performed in all affected or at-risk individuals from 4 Chinese families presenting with autosomal dominant cerebellar ataxia and decreased visual acuity. The size of the (CAG)(n) array of the SCA7 gene was detected by polymerase chain reaction, polyacrylamide gel electrophoresis, and related techniques in the 4 families and 67 healthy controls. The relationship between expanded repeat number and age of onset was statistically analyzed. RESULTS: The SCA7 mutation was identified in 2 families. Clinical study revealed that great variation occurred in the age of onset, initial symptoms, and associated signs. Meanwhile, the analysis of 11 parent-child couples demonstrated the existence of marked anticipation. Some distinct retinal changes were noted in 2 affected patients. All SCA7 patients in our series exhibited expanded CAG repeats, ranging from 44 to 85 repeats, with a strong negative correlation between repeat size and age of onset. Repeat lengths of expanded alleles showed somatic mosaicism in leukocyte DNA. There were some subtle clinical differences between the SCA7-positive and -negative cases. CONCLUSIONS: Clinical variation occurred not only among the SCA7 families but also within the same kindred. Meiotic and mitotic instability of the CAG repeat in the SCA7 gene were demonstrated, and intergenerational instability of the array was associated with the clinical phenomenon of anticipation. Arch Neurol. 2000;57:1513-1518

Adolescent↗
PubMed2000

Cloning and characterization of the Dictyostelium discoideum cycloartenol synthase cDNA.

Cycloartenol synthase converts oxidosqualene to cycloartenol, the first carbocyclic intermediate en route to sterols in plants and many protists. Presented here is the first cycloartenol synthase gene identified from a protist, the cellular slime mold Dictyostelium discoideum. The cDNA encodes an 81-kDa predicted protein 50-52% identical to known higher plant cycloartenol synthases and 40-49% identical to known lanosterol synthases from fungi and mammals. The encoded protein expressed in transgenic Saccharomyces cerevisiae converted synthetic oxidosqualene to cycloartenol in vitro. This product was characterized by 1H and 13C nuclear magnetic resonance and gas chromatography-mass spectrometry. The predicted protein sequence diverges sufficiently from the known cycloartenol synthase sequences to dramatically reduce the number of residues that are candidates for the catalytic difference between cycloartenol and lanosterol formation.

Amino Acid Sequence↗
PubMed2000

The USA-derived transcriptional coactivator PC2 is a submodule of TRAP/SMCC and acts synergistically with other PCs.

PC2, the high-molecular weight constituent of the potent USA transcriptional coactivator fraction, was identified as a Mediator-like complex. Its composition resembles that of the TRAP/SMCC complex, but PC2 is distinguished by the prominent absence of the SRB10 and SRB11 kinase/cyclin pair, as well as several additional polypeptides. Furthermore, affinity-purified PC2, which lacks independent activity, acts in synergy with USA-derived coactivators PC3/topoisomerase I and PC4 to mediate the effects of a variety of activators (including VP16, the synthetic activator GAL4-AH, and the orphan nuclear receptor HNF4) and thus recapitulates partial USA coactivator function.

HeLa Cells↗