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Biomedical subjects

H Guo

Publications and source records attributed to H Guo.

At least 127 records · Page 7Linked to original sources
PubMed2000

[Surgical treatment of malignant esophageal tumors in PUMC Hospital].

OBJECTIVE: To study how to prolong the postoperative survival time of the patients with malignant esophageal tumors. METHODS: The clinical data of 1,098 patients with malignant esophageal tumors from 1961 to 1992 were retrospectively analyzed. The deletion of fragile histamine triplet(FHIT) gene(a tumor suppressor gene) in 30 fresh esophageal samples obtained in 1996 was detected with PCR and RT-PCR. RESULTS: The resectability was raised gradually and the operative morbidity and mortality decreased year-by-year, but there was no significant improvement on the postoperative 5-year survival rate. Delayed diagnosis and ir-radical resection influenced the long term survival. The deletion of cDNA of FHIT gene was 64.2% in esophageal cancer and 20% in the resected margin of the cancer. CONCLUSIONS: High atypical hyperplasia in esophageal epithelium and deletion of FHIT gene in esophageal cancer and its resected margin are pathological and molecular markers for early diagnosis of esophageal cancer respectively, and the latter may be one of the molecular markers for the resection. Early diagnosis and treatment, radical resection, and postoperative nutritional support are essential for the improvement of the postoperative survival time of the patients.

Acid Anhydride Hydrolases↗
PubMed1999

Neuronally modulated transcription of a glycine transporter in rat dorsal cochlear nucleus and nucleus of the medial trapezoid body.

Neurotransmitter transporters limit transmitter concentration at the postsynaptic membrane by removing neurotransmitters from the synaptic cleft. Not only do neurotransmitter transporters contribute to the regulation of synaptic transmission, but they themselves might be dynamically regulated by neuronal activity of the neurons in which they are expressed. In this experiment, we investigated the question of whether the transcription of two different glycine transporters, Glyt1 and Glyt2, is influenced by neuronal activity. These transporters are found in the dorsal cochlear nucleus (DCN) and medial nucleus of the trapezoid body. Glyt1 and Glyt2 mRNA were measured by using hybridization histochemistry and a semiquantitative reverse transcription polymerase chain reaction. Decreases in auditory primary afferent activity, caused by either unilateral labyrinthectomy or disruption of the middle ear ossicles, caused a reduction in Glyt2, but not Glyt1 mRNA in the ipsilateral DCN and in the contralateral medial nucleus of the trapezoid body. Acoustic stimulation at either 10 kHz or 40 kHz was used to provide controlled increases in primary afferent activity, evoking localized increases in Glyt2 mRNA in clusters of neurons in the DCN. The location of these clusters corresponded to the regions of the auditory tonotopic map devoted to these frequencies. The duration of changes in Glyt2 mRNA evoked by unilateral labyrinthectomy, measured with the reverse transcription polymerase chain reaction, was 5-10 days. These data provide the first example of in vivo regulation of transporter transcription by neuronal activity.

Amino Acid Transport Systems, Neutral↗
PubMed1999

[DNA cloning and partial sequence analysis of EBV LMP1 gene isolated from human nasopharyngeal carcinoma cell line SUNE1].

OBJECTIVE: To study the variation of EBV LMP1 encoding gene isolated from human nasopharyngeal carcinoma cell line SUNE1 in Guangdong. METHODS: The EBV LMP1 gene was amplified from the SUNE1 cell genome by PCR and then the recombinant vector was constructed by inserting the PCR fragment into pcDNA3. The encoding EBV LMP1 spanning from exon1 to exon3 in recombinant vector was sequenced by the Sequence Analyzer. RESULTS: The 1,312 bp encoding EBV LMP1 pieces in 2.6 kb PCR fragments were compared with the same EBV segments in B95-8 cell line. The data indicated that the rate of nucleotide sequence homology between the two fragments is 98.5% and the rate of amino acid is 96%. The restricted enzyme site of Xho I in exon1 was deleted in SUNE1 but the 30 bp deletion at the carboxyl terminus in most Chinese NPC LMP1 gene was not present. CONCLUSION: Although the LMP1 gene derived from SUNE1 had greater tumorigenicity than that derived from B95-8 cell, the high homology rate of nucleotide and amino acid sequences between them indicated that it was not the result from the variation of certain nucleotide sites but the change in amino acid domain.

Amino Acid Sequence↗
PubMed1999

[Effect of dengue virus infection on the production of ET-1 and PGI2 by human vascular endothelial cells].

OBJECTIVE: To study the effect of dengue virus infection on the production of endothelin 1(ET-1) and prostacyclin 2(PGI2) by human umbilical cord vein endothelial cells (HUVECs). METHODS: HUVECs were infected by dengue-2 virus (DV-2), the culture supernatants were collected at 4, 24, 48, 72 and 96 hours postinfection, and the levels of ET-1 and PGI2 were measured by radio-immunoassay. RESULTS: The results showed that inhibition of production of ET-1 and PGI2 was induced by dengue virus infection in HUVECs. Marked inhibition of ET-1 and PGI2 production was observed as early as 4 h postinfection and the inhibitory effect continued until 96 h postinfection. Significant differences were shown between the ET-1 concentration of the virus-infected and non-infected cells. Nevertheless, the inhibitory effect of dengue virus infection on the production of PGI2 gradually decreased and the PGI2 concentration reverted to normal level at 96 h postinfection. No significant difference between the PGI2 concentration of the virus-infected and non-infected cells was seem. CONCLUSION: The present study suggests that dengue virus infection of vascular endothelial cells could affect their normal functions of secretion of vasoactive substances, resulting in increased vascular permeability and impairment of homostasis and blood coagulation. Therefore, functional impairment of vascular endothelial cells induced by dengue virus might be an important aspect in the pathogenesis of DHF/DSS.

Cells, Cultured↗
PubMed1999

[The use of immunological methods for the detection of phycotoxin and shellfish toxin].

Harmful algae can do great harm to organisms even to human through food chain by accumulating in shellfish and fish or by themselves. The immunological examination technique is fast, easy and accurate even in trace amount of phycotoxin and shellfish toxin. The theory of immunological diagnosis as well as the prospect and defect of these methods and their application in phycotoxin and shellfish toxin determination are introduced. The method deserves spreading and using in routine monitoring program.

Animals↗
PubMed1999

Expression and regulation of the chicken Nkx-6.2 homeobox gene suggest its possible involvement in the ventral neural patterning and cell fate specification.

Rapid accumulating evidence has suggested that the homeodomain transcription factors of the Nkx family play important roles in controlling vertebrate organ patterning and differentiation. In this study, we report the cloning, expression and regulation of a novel chicken homeobox gene, cNkx-6.2, whose expression is similar, but not identical, to that of mouse Nkx-6.2. The earliest expression of cNkx-6.2 was detected at the neural plate stage in the prospective midbrain and hindbrain regions. As the neural development proceeds, cNkx-6.2 expression was restricted in the ventral region of the entire neural axis except the forebrain region. At late stages of development, cNkx-6.2 expression is downregulated in the ventricular neuroepithelial cells, but subsequently upregulated in a sub-population of cells. Tissue recombination and explant culture experiments demonstrated that expression of cNkx-6.2 can be induced by the notochord signal and purified SHH protein, and repressed by BMP-4 and -7, indicating that the cNkx-6.2 expression can be influenced by both ventral and dorsal midline signals. Taken together, these studies have suggested two different roles for the cNkx-6.2 transcription factor: participating in the Shh-initiated ventral patterning during early CNS development and controlling cell fate specification and differentiation during late development.

Amino Acid Sequence↗
PubMed1999

Microfabrication techniques using focused ion beams and emergent applications.

The application of focused ion beam (FIB) machining in several technologies aimed at microstructure fabrication is presented. These emergent applications include the production of micromilling tools for machining of metals and the production of microsurgical tools. An example of the use of microsurgical manipulators in a circulatory system measurement is presented. The steps needed to transform the laboratory fabrication of these tools and manipulators into a routine FIB production process are discussed. The ion milling of three-dimensional cavities by the exact solution of a mathematical model of the FIB deflection is demonstrated. A good agreement between the model calculation and the ion beam control has been obtained for parabolic and cosine cross-section features with planes of symmetry.

Animals↗
PubMed1999

GRAB proteins, novel members of the NAC domain family, isolated by their interaction with a geminivirus protein.

Geminiviruses encode a few proteins and depend on cellular factors to complete their replicative cycle. As a way to understand geminivirus-host interactions, we have searched for cellular proteins which interact with viral proteins. By using the yeast two-hybrid technology and the wheat dwarf geminivirus (WDV) RepA protein as a bait, we have isolated a family of proteins which we termed GRAB (for Geminivirus Rep A-binding). We report here the molecular characterization of two members, GRAB1 and GRAB2. We have found that the 37 C-terminal amino acids of RepA are required for interaction with GRAB proteins. This region contains residues conserved in an equivalent region of the RepA proteins encoded by other viruses of the WDV subgroup. The N-terminal domain of GRAB proteins is necessary and sufficient to interact with WDV RepA. GRAB proteins contain an unique acidic C-terminal domain while their N-terminal domain, of ca. 170 amino acids, are highly conserved in all of them. Interestingly, this conserved N-terminal domain of GRAB proteins exhibits a significant amino acid homology to the NAC domain present in proteins involved in plant development and senescence. GRAB1 and GRAB2 mRNAs are present in cultured cells and roots but are barely detectable in leaves. GRAB expression inhibits WDV DNA replication in cultured wheat cells. Our studies highlight the importance that the pathway(s) mediated by GRAB proteins, as well as by other NAC domain-containing proteins, might have on geminivirus DNA replication in connection to plant growth, development and senescence pathways.

Amino Acid Sequence↗
PubMed1999

The Arabidopsis blue light receptor cryptochrome 2 is a nuclear protein regulated by a blue light-dependent post-transcriptional mechanism.

Cryptochrome 2 is a flavin-type blue light receptor mediating floral induction in response to photoperiod and a blue light-induced hypocotyl growth inhibition. cry2 is required for the elevated expression of the flowering-time gene CO in response to long-day photoperiods, but the molecular mechanism underlying the function of cry2 is not clear. The carboxyl domain of cry2 bears a basic bipartite nuclear localization signal, and the cry2 protein was co-fractionated with the nucleus. Analysis of transgenic plants expressing a fusion protein of CRY2 and the reporter enzyme GUS (GUS-CRY2) indicated that the GUS-CRY2 fusion protein accumulated in the nucleus of transgenic plants grown in dark or light. The C-terminal domain of cry2 that contains the basic bipartite nuclear localization signal was sufficient to confer nuclear localization of the fusion protein. Phenotypic analysis of transgenic plants expressing the fusion protein GUS-CRY2 demonstrated that GUS-CRY2 acts as a functional photoreceptor in vivo, mediating the blue light-induced inhibition of hypocotyl elongation. These results strongly suggest that cry2 is a nuclear protein. Although no obvious light regulation was found for the nuclear compartmentation of GUS-CRY2 fusion protein, the abundance of GUS-CRY2 was regulated by blue light in a way similar to that of cry2.

Amino Acid Sequence↗
PubMed1999

DNA microarrays of the complex human cytomegalovirus genome: profiling kinetic class with drug sensitivity of viral gene expression.

We describe, for the first time, the generation of a viral DNA chip for simultaneous expression measurements of nearly all known open reading frames (ORFs) in the largest member of the herpesvirus family, human cytomegalovirus (HCMV). In this study, an HCMV chip was fabricated and used to characterize the temporal class of viral gene expression. The viral chip is composed of microarrays of viral DNA prepared by robotic deposition of oligonucleotides on glass for ORFs in the HCMV genome. Viral gene expression was monitored by hybridization to the oligonucleotide microarrays with fluorescently labelled cDNAs prepared from mock-infected or infected human foreskin fibroblast cells. By using cycloheximide and ganciclovir to block de novo viral protein synthesis and viral DNA replication, respectively, the kinetic classes of array elements were classified. The expression profiles of known ORFs and many previously uncharacterized ORFs provided a temporal map of immediate-early (alpha), early (beta), early-late (gamma1), and late (gamma2) genes in the entire genome of HCMV. Sequence compositional analysis of the 5' noncoding DNA sequences of the temporal classes, performed by using algorithms that automatically search for defined and recurring motifs in unaligned sequences, indicated the presence of potential regulatory motifs for beta, gamma1, and gamma2 genes. In summary, these fabricated microarrays of viral DNA allow rapid and parallel analysis of gene expression at the whole viral genome level. The viral chip approach coupled with global biochemical and genetic strategies should greatly speed the functional analysis of established as well as newly discovered large viral genomes.

Base Sequence↗
PubMed1999

Nasal administration of transforming growth factor-beta1 induces dendritic cells and inhibits protracted-relapsing experimental allergic encephalomyelitis.

Cytokines have a crucial role in initiation and perturbation of EAE that represents an animal model of multiple sclerosis (MS). Administration of transforming growth factor-beta1 (TGF-beta1) to EAE mice improves clinical EAE and prevents relapses by unknown mechanisms. Administering low doses of TGF-beta1 nasally, we confirmed that TGF-beta1 inhibited development and relapse of protracted-relapsing EAE (PR-EAE) in DA rats. Infiltration of CD4+ T-cells and macrophages within the central nervous system was clearly reduced, while proliferation and IFN-gamma secretion of mononuclear cells (MNC) was augmented in TGF-beta1-treated EAE rats compared to PBS-treated control EAE rats. TGF-beta1 administered nasally also increased nitric oxide production and CD4+ T cell apoptosis. TGF-beta1 treated rats showed augmented proliferation of dendritic cells (DC) compared to MNC. These data imply that low doses of TGF-beta1 given by the nasal route prevent PR-EAE and upregulate DC functions that may be involved for disease prevention.

Administration, Intranasal↗
PubMed1999

Antagonistic actions of Arabidopsis cryptochromes and phytochrome B in the regulation of floral induction.

The Arabidopsis photoreceptors cry1, cry2 and phyB are known to play roles in the regulation of flowering time, for which the molecular mechanisms remain unclear. We have previously hypothesized that phyB mediates a red-light inhibition of floral initiation and cry2 mediates a blue-light inhibition of the phyB function. Studies of the cry2/phyB double mutant provide direct evidence in support of this hypothesis. The function of cryptochromes in floral induction was further investigated using the cry2/cry1 double mutants. The cry2/cry1 double mutants showed delayed flowering in monochromatic blue light, whereas neither monogenic cry1 nor cry2 mutant exhibited late flowering in blue light. This result suggests that, in addition to the phyB-dependent function, cry2 also acts redundantly with cry1 to promote floral initiation in a phyB-independent manner. To understand how photoreceptors regulate the transition from vegetative growth to reproductive development, we examined the effect of sequential illumination by blue light and red light on the flowering time of plants. We found that there was a light-quality-sensitive phase of plant development, during which the quality of light exerts a profound influence on flowering time. After this developmental stage, which is between approximately day-1 to day-7 post germination, plants are committed to floral initiation and the quality of light has little effect on the flowering time. Mutations in either the PHYB gene or both the CRY1 and CRY2 genes resulted in the loss of the light-quality-sensitive phase manifested during floral development. The commitment time of floral transition, defined by a plant's sensitivity to light quality, coincides with the commitment time of inflorescence development revealed previously by a plant's sensitivity to light quantity - the photoperiod. Therefore, the developmental mechanism resulting in the commitment to flowering appears to be the direct target of the antagonistic actions of the photoreceptors.

Arabidopsis↗
PubMed1999

[Long-term evolution of C-terminal of HCV NS3 protein containing the predicted CTL epitopes in two HCV patients].

OBJECTIVE: To investigate the Long-term evolution of NS3 C-terminal protein containing the predicted CTL epitopes. METHODS: The HLA typing was determined serologically in two chronic HCV patients. Based on this, the HLA restricted CTL epitopes were predicted by HLA binding motif. Sera samples were amplified by PCR, HCV was sequenced and translated into proteins. The changes of predicted CTL epitopes were analysed. RESULTS: No obvious change was observed in predicted CTL epitopes in two chronic HCV patients during 5 and 3 years. CONCLUSION: It demonstrated that the C-terminal of HCV NS3 protein containing the predicted CTL epitopes may have no relationship with HCV persistence.

Adult↗
PubMed1999

Surgical treatment of trigeminal neurinomas.

OBJECTIVE: To investigate the best surgical approach for the removal of trigeminal neurinomas (TNs). METHODS: A retrospective analysis of 75' patients with TNs in Huashan Hospital was carried out. RESULTS: In the early group (1978-1984), a series of conventional intradural approaches were used; in the late group (1985-1995), an epidural approach via the skull-base craniotomy was used. Total tumor removal was achieved in 58% (20/35) of patients in the early group and 80% (32/40) in the late group (P < 0.025). Temporary and permanent cranial nerve morbidity were 62.7% and 37% in the early group and 28.1% and 10% in the late group (P < 0.001). CONCLUSION: The best microsurgical approach for the removal of trigeminal neurinomas except those confined to the posterior fossa is epidural approach or epidurotransduro-transtentorial approach via the skull-base craniotomy.

Cranial Nerve Neoplasms↗