Biomedical subjects

X Dong

Publications and source records attributed to X Dong.

At least 109 records · Page 6Linked to original sources

PubMed2000

[The immortalized cell lines induced by human papillomavirus type 16 (HPVS 16) YY1 binding-site mutants have some characteristics of transformed cells].

OBJECTIVE: To study the biological characteristics of the immortalized cell lines of human keratinocytes from foreskin induced by human papillomavirus type 16 (HPV 16) YY1 binding-site mutants. METHODS: The cellular extracts of immortalized cell lines were prepared and the cellular endogenous p53 proteins were determined with Western blot. The cellular telomerase activities were analyzed with TRAP. The immortalized cells were incubated in a soft agarose medium containing 10% FCS and the anchorage-independent growth abilities of the tested cell lines were evaluated. RESULTS: Western blot showed that the endogenous p53 protein in all 4 tested clones were undetectable. The telomerases were clearly identified within the 4 tested cell lines, and showed an increasing activity along with the passages of the cells. All the clones were unable to grow in the soft-agarose medium during the earlier passages, but three of them showed anchorage-independent-growth at the passages of 30-35. CONCLUSIONS: The immortalized cell lines induced by the HPV 16 YY1 binding-site mutants have active telomerase activity and ability of anchorage-independent growth.

Agar↗

PubMed2000

[Presence of genetic rearrangements in E1/E2 regions of episomal HPV 16 isolates from cervical carcinomas 5-8].

OBJECTIVE: Analysis of genetic situations of E1/E2 region of episomal HPV 16 isolates from cervical carcinomas. METHODS: Physical statues of HPV 16 DNAs from cervical carcinomas were analyzed by Southern blot hybridization. E1/E2 regions of episomal RPV 16 isolates were amplified by PCR, and the PCR products were cloned and sequenced. RESULTS: Eight isolates from totally 28 cases showed extrachromosomal HPV 16 DNA. PCR cloned sequence analysis revealed that all the eight isolates contained intact E1/E2 regions, whereas 4 isolates had different ratios of genetic rearrangements, including insertion of E1 repeat sequence and several deletions. Only one case showed the same G deletion at position 1138 as HPV 16 prototype. CONCLUSIONS: DNA rearrangements were present in E1/E2 regions of episomal HPV 16 isolates from cervical cancers and might play a role in tumorigenesis. Different viral genotypes in an identical tumor tissue might indicate that the tumor occurring at the same position of a patient may derive from two or even more cell clones.

DNA, Viral↗

PubMed2000

[Preparation of polyclonal antibody to human prion protein using the expressed GST-PrP fusion protein as antigen].

OBJECTIVE: Preparing specific antibody to prion protein. METHODS: Using prokaryotic expressed GST-PrP fusion protein as antigen, rabbits were immunized subcutaneously. RESULTS: ELISA assay revealed that the titer of the prepared antiserum against expressed PrP protein was as high as 1:128 000. Western blot test showed that the antiserum was able to react with the in vitro expressed intact and different lengths of C-terminus truncated PrP proteins, as well as the native PrP proteins from brain homogenization of human and mouse. CONCLUSIONS: The prokaryotic expressed GST-PrP fusion protein can efficiently elicit in immunized animals the PrP-specific antibody.

Animals↗

PubMed2000

[Diagnosis and treatment of colorectal non-epithelial malignancies].

OBJECTIVE: To summarize the experience in the diagnosis and treatment of colorectal malignancies of non-epithelial origin. METHODS: Seventy five cases of colorectal non-epithelial malignancy who had undergone treatment in our hospital from 1975 to 1996 were retrospectively analysed with their clinicopathologic characteristics, treatment and prognosis. RESULTS: Patients usually had no specific clinical manifectation, such as bloody purulent stool or mucous stool. No apparent mucosa damage other than changes due to pressure from without was found on x-ray and colonoscopic examinations. Diagnosis depended on pathology and clinical manifestations. Metastasis occurred mainly by hematogenous spread and local invasion. In this series, 21 cases (6 liomyosarcomas; 15 lymphosarcoma) had local recurrence. The principle treatment was operation, which was performed two or several times in patients with local recurrences. Except lymphosarcoma, the disease was not sensitive to chemotherapy or radiotherapy. The survival rate was significantly lower than that of colorectal cancers. CONCLUSION: The disease is apt to be misdiagnosed or missed because it lacks specific symptoms. Local recurrence and hematogenous metastasis are common.

Adolescent↗

PubMed2000

[A report on investigation and clinical application of corneal storage media].

OBJECTIVE: To develop intermediate term storage media suitable for Chinese eye banks. METHODS: Corneal buttons of rabbits were stored in DX solution freshly prepared. After storage for several days, the survival rate of the corneal endothelial cells was examined, enzymohistochemical staining and ultrastructural examinations were carried out for the buttons. Thirty-seven human corneas stored in DX solution for 3 - 11 days were used for corneal transplantation, clinically. RESULTS: There was no significant difference between rabbit corneal buttons stored in DX sol. and in Optisol in any indices studied. 37 grafts were all transparent in 1 week after transplantation, and the mean endothelial cell density was (2,204.56 +/- 689.56) cells/mm(2). CONCLUSION: As a safe and efficient intermediate term (about 1 week) storage medium, DX sol. is appropriate for Chinese eye banks.

Adrenal Cortex Hormones↗

PubMed2000

[Experimental study on herpes simplex virus-1 functional gene latency in cornea].

OBJECTIVE: To investigate the possible existence of herpes simplex virus-1 (HSV-1) functional gene latency in cornea. METHODS: A herpes simplex keratitis (HSK) model was established in New Zealand White (NZW) rabbit corneas, latently infected corneas were transplanted to one eye of each naive NZW rabbit. One week after the operation, the corneal buttons were removed and divided into three portions. One portion was processed for HSV-1 antigen detection, another was for HVS-1 latency associated transcript (LAT), thymidine kinase (TK) and DNA polymerase gene detections by polymerase chain reaction (PCR), and the last portion after tissue culture for 3 weeks, it was co-cultured with rabbit kidney cells (RK) for one week, then the expression of HSV-1 antigen in the RK cells and this portion of corneal button was detected. RESULT: In the 15 corneal samples negative for HSV-1 antigen, LAT gene was detected in 8 samples, TK gene in 10 and DNA polymerase gene in 6 samples. HSV-1 antigen was detected in 3 samples of RK cells and 6 cultured corneal samples. CONCLUSION: HSV-1 functional genes are retained in latently infected cornea.

Animals↗

PubMed2000

[A dynamic study on the surgically induced astigmatism after phacoemulsification through three different-sized scleral tunnel incisions].

OBJECTIVE: To compare the changes in the values and directions of surgically induced astigmatism (SIA) after phacoemulsification with three different-sized scleral tunnel incisions and to evaluate their clinical results. METHODS: The patients were divided into three groups; the length of the scleral tunnel incision was 3.2, 5.5 and 7.0 mm respectively in A, B and C groups. Keratometry measurements were obtained preoperatively, at postoperative 1 week, 1 month and 6 months respectively. SIAs were analyzed by "Cravy vector method". The mean SIA and uncorrected visual acuity were compared among the groups up to 6 months postoperatively. RESULTS: Eyes in A group displayed significantly less mean SIA and better uncorrected visual acuity than B and C groups at 1 week postoperatively (P < 0.05), but there were no significant differences between any groups at 1 month, 3 months and 6 months postoperatively (P > 0.05). There were no significant differences in the mean SIA and uncorrected visual acuity between B and C groups throughout the whole study period (P > 0.05). CONCLUSIONS: SIAs in eyes of 3.2 mm incision group of phacoemulsification are less and more stable; a better and quicker rehabilitation of uncorrected visual acuity can be obtained in the early postoperative period.

Astigmatism↗

PubMed2000

[A preliminary report of ocular surface disease treated by limbal transplantation].

OBJECTIVE: To evaluate the effect of ocular surface disease treated by limbal transplantation. METHODS: In a prospective study, 5l eyes of 50 patients were treated with three kinds of surgical techniques: first, conjunctival limbal autograft (CLAU) transplantation; second, corneal lamellar allograft combined with limbal autograft transplantation and third, corneal lamellar allograft combined with limbal allograft transplantation. Their effects were evaluated. RESULTS: All of the 18 patients of CLAU group were cured. The second surgical technique resulted in restoration of a stable ocular surface in 19 of 20 cases. 10 patients' visual acuities were improved two or more than two lines. 13 eyes of 12 patients were treated with the third surgical technique, resulting in graft ulceration in 4 patients and graft rejection in 4 patients with bad prognosis. CONCLUSIONS: The effect of unilateral ocular surface disease treated with limbal autograft transplantation is satisfactory. For bilateral ocular surface disease, the method of limbal allograft transplantation should be improved to resolve some problems such as graft rejection.

Adolescent↗

PubMed2000

[A serological investigation of Legionella infection in eight-species of poultry and domestic animals in Sichuan province].

OBJECTIVE: To understand the prevalence rates of Legionella infection in poultries and domestic animals in Sichuan province. METHODS: Serological investigation of antibodies against Legionella pneumophila serogroups 1 - 14 and Legionella micdadei was carried out, using microagglutination test (MAT) in eight species of poultries and domestic animals. RESULTS: Infections with multiple serogroups were identified. However, each species had its own major serogroup with positive rates of different serogroups ranging from 0.83% to 59.18%. Positive rates of the poultry and domestic animals were accounted for 7.73% and 4.25% respectively. CONCLUSION: It was suggested that poultries and domestic animals were widely infected with Legionella. It is important to carry out epidemiological surveillance in these domestic animals, poultries and environment for a better control program of this disease.

Animals↗

PubMed2000

[Investigation on E. coli O157 in Fujian, China].

OBJECTIVES: To understand the distribution of Escherichia coli O157 (E. coli O157) in human beings, livestock and fowls in Fujian Province, and biological features of the isolated strains. METHODS: Fecal specimens from diarrheal patients, livestock and fowls and meat specimens in Putian and Fuzhou were collected for detection of E. coli O157 during 1997 - 1998. RESULTS: A total of 2,725 specimens were detected, and 76 strains of E. coli O157 were isolated from pigs, pigeons, cattle, chickens, ducks, et al., as well as from the diarrheal patients. These strains could be classified into three types according to their serological tests, including 33 strains of O157: H7, 21 strains of O157: NM, and 22 strains of O157: H?. Detecting rate of E. coli O157 from pigs was the highest. The isolated strains could cause diarrhea in human and obvious pathological changes in the intestines of mice, but could not produce cytotoxin Vero, or heat-stable or heat-liable enterotoxin LT or ST. CONCLUSIONS: There were three types of E. coli O157 in Fujian. But, pathogenic factors of O157: H7 and O157: NM were different from those reported abroad. It suggested that there possibly existed some new pathogenic factors.

Animals↗

PubMed2000

[Changes of vWF in vascular endothelial cells with acute hypoxia].

OBJECTIVE: To investigate changes of vWF in vascular endothelial cells with acute hypoxia and assess its significance in the study of vascular injury and hypercoagulability. METHODS: vWF in vascular endothelial cells and in blood were measured by immunohistochemical staining image analysis and ELISA technique. Fibrin was displayed by phosphotungstic hematoxylin staining. RESULTS: The amount of vWF in vascular endothelial cells decreased progressively, while in blood increased progressively with hypoxia. Fibrin prominently increased with hypoxia. CONCLUSION: Acute hypoxia caused severe injury of vascular endothelial cells which resulted in release of vWF into blood from endothelial cells. The vWF amounts in blood may reflect the hypercoagulability, and may serve as a useful indicator of vascular injury and hypercoagulability.

Animals↗

PubMed1999

Binding and uptake of agalactosyl IgG by mannose receptor on macrophages and dendritic cells.

Increased levels of agalactosyl IgG (G0 IgG) are found in several autoimmune diseases, including rheumatoid arthritis, in which they are correlated with severity of the disease. To investigate whether structural alteration of IgG may lead to aberrant processing and presentation of IgG peptides as autoantigens, we have studied uptake of G0 IgG by human dendritic cells and macrophages cultured from PBMC. We found that enzymatic removal of terminal galactose residues, which exposes N-acetylglucosamine residues, increases uptake of soluble IgG mediated by mannose receptor on macrophages and dendritic cells. Efficient uptake appears to require recycling of the receptor, can be blocked by saccharides or Abs reactive with mannose receptor, and is dependent upon the state of maturation of the dendritic cells. No differences between IgG isotypes in ability to be internalized by APC were identified, suggesting that uptake would not be limited to a particular subset of Abs. These results suggest a novel pathway by which Abs or Ag-Ab complexes can be taken into dendritic cells and macrophages, and potentially generate epitopes recognized by T cells. These findings may have particular relevance for autoimmune disorders characterized by high levels of G0 IgG.

Antibodies, Monoclonal↗

PubMed1999

Identification and cloning of a negative regulator of systemic acquired resistance, SNI1, through a screen for suppressors of npr1-1.

Systemic acquired resistance (SAR) is a plant immune response induced after a local infection by necrotizing pathogens. The Arabidopsis NPR1 gene is a positive regulator of SAR, essential for transducing the SAR signal salicylic acid (SA). Mutations in the NPR1 gene abolish the SA-induced expression of pathogenesis-related (PR) genes and resistance to pathogens. To identify additional regulators of SAR, we screened for suppressors of npr1-1. In the npr1-1 background, the sni1 (suppressor of npr1-1, inducible 1) mutant shows near wild-type levels of PR1 expression and resistance to pathogens after induction. Restoration of SAR in npr1-1 by the recessive sni1 mutation indicates that wild-type SNI1 may function as a negative regulator of SAR. We cloned the SNI1 gene and found that it encodes a leucine-rich nuclear protein.

Amino Acid Sequence↗

PubMed1999

[Expression of human prp gene in prokaryotic cells using GST fusion protein expression system].

OBJECTIVE: To study the biological features of cell-surface protein PrPc, which is thought to be involved in the prion-associated diseases after converting to a proteinase-resistant isoform PrPSc posttranslationally, and to establish an effective immunologic diagnostic method using PrPc as antigen. METHODS: Amplifying and cloning the human prp gene from lymphocytes of two normal Chinese, after confirmed by DNA sequence analysis, the genes were separately subcloned into a GST-fusion expression plasmid. RESULTS: Sequence analysis showed that one contatined a point mutation that induced the 65th amino acid "Trp" inverting to a stop codon "TAG", whereas the other had the same sequence as the published standard prp gene. Both the standard and the mutated prp genes were separately subcloned into a GST fusion protein expression vector and expressed in the prokaryotic cells effectively. Western blot assay revealed that both of them expressed GST-PrP fusion proteins and could be recognized by PrP specific monoclonal antibody. CONCLUSION: It suggests that human PrP protein can be expressed in the GST fusion protein expression system and the expressed proteins hold good immune-reactivity.

Amino Acid Sequence↗

PubMed1999

Interaction of NPR1 with basic leucine zipper protein transcription factors that bind sequences required for salicylic acid induction of the PR-1 gene.

The Arabidopsis thaliana NPR1 has been shown to be a key regulator of gene expression during the onset of a plant disease-resistance response known as systemic acquired resistance. The npr1 mutant plants fail to respond to systemic acquired resistance-inducing signals such as salicylic acid (SA), or express SA-induced pathogenesis-related (PR) genes. Using NPR1 as bait in a yeast two-hybrid screen, we identified a subclass of transcription factors in the basic leucine zipper protein family (AHBP-1b and TGA6) and showed that they interact specifically in yeast and in vitro with NPR1. Point mutations that abolish the NPR1 function in A. thaliana also impair the interactions between NPR1 and the transcription factors in the yeast two-hybrid assay. Furthermore, a gel mobility shift assay showed that the purified transcription factor protein, AHBP-1b, binds specifically to an SA-responsive promoter element of the A. thaliana PR-1 gene. These data suggest that NPR1 may regulate PR-1 gene expression by interacting with a subclass of basic leucine zipper protein transcription factors.

Amino Acid Sequence↗

PubMed1999

ebi regulates epidermal growth factor receptor signaling pathways in Drosophila.

ebi regulates the epidermal growth factor receptor (EGFR) signaling pathway at multiple steps in Drosophila development. Mutations in ebi and Egfr lead to similar phenotypes and show genetic interactions. However, ebi does not show genetic interactions with other RTKs (e.g., torso) or with components of the canonical Ras/MAP kinase pathway. ebi encodes an evolutionarily conserved protein with a unique amino terminus, distantly related to F-box sequences, and six tandemly arranged carboxy-terminal WD40 repeats. The existence of closely related proteins in yeast, plants, and humans suggests that ebi functions in a highly conserved biochemical pathway. Proteins with related structures regulate protein degradation. Similarly, in the developing eye, ebi promotes EGFR-dependent down-regulation of Tramtrack88, an antagonist of neuronal development.

Amino Acid Sequence↗

PubMed1999

Concurrent inhibition and excitation of phrenic motoneurons during inspiration: phase-specific control of excitability.

The movements that define behavior are controlled by motoneuron output, which depends on the excitability of motoneurons and the synaptic inputs they receive. Modulation of motoneuron excitability takes place over many time scales. To determine whether motoneuron excitability is specifically modulated during the active versus the quiescent phase of rhythmic behavior, we compared the input-output properties of phrenic motoneurons (PMNs) during inspiratory and expiratory phases of respiration. In neonatal rat brainstem-spinal cord preparations that generate rhythmic respiratory motor outflow, we blocked excitatory inspiratory synaptic drive to PMNs and then examined their phase-dependent responses to superthreshold current pulses. Pulses during inspiration elicited fewer action potentials compared with identical pulses during expiration. This reduced excitability arose from an inspiratory-phase inhibitory input that hyperpolarized PMNs in the absence of excitatory inspiratory inputs. Local application of bicuculline blocked this inhibition as well as the difference between inspiratory and expiratory firing. Correspondingly, bicuculline locally applied to the midcervical spinal cord enhanced fourth cervical nerve (C4) inspiratory burst amplitude. Strychnine had no effect on C4 output. Nicotinic receptor antagonists neither potentiated C4 output nor blocked its potentiation by bicuculline, further indicating that the inhibition is not from recurrent inhibitory pathways. We conclude that it is bulbospinal in origin. These data demonstrate that rapid changes in motoneuron excitability occur during behavior and suggest that integration of overlapping, opposing synaptic inputs to motoneurons is important in controlling motor outflow. Modulation of phasic inhibition may represent a means for regulating the transfer function of PMNs to suit behavioral demands.

Animals↗

PubMed1999

Erf2, a novel gene product that affects the localization and palmitoylation of Ras2 in Saccharomyces cerevisiae.

Plasma membrane localization of Ras requires posttranslational addition of farnesyl and palmitoyl lipid moieties to a C-terminal CaaX motif (C is cysteine, a is any aliphatic residue, X is the carboxy terminal residue). To better understand the relationship between posttranslational processing and the subcellular localization of Ras, a yeast genetic screen was undertaken based on the loss of function of a palmitoylation-dependent RAS2 allele. Mutations were identified in an uncharacterized open reading frame (YLR246w) that we have designated ERF2 and a previously described suppressor of hyperactive Ras, SHR5. ERF2 encodes a 41-kDa protein with four predicted transmembrane (TM) segments and a motif consisting of the amino acids Asp-His-His-Cys (DHHC) within a cysteine-rich domain (CRD), called DHHC-CRD. Mutations within the DHHC-CRD abolish Erf2 function. Subcellular fractionation and immunolocalization experiments reveal that Erf2 tagged with a triply iterated hemagglutinin epitope is an integral membrane protein that colocalizes with the yeast endoplasmic reticulum marker Kar2. Strains lacking ERF2 are viable, but they have a synthetic growth defect in the absence of RAS2 and partially suppress the heat shock sensitivity resulting from expression of the hyperactive RAS2(V19) allele. Ras2 proteins expressed in an erf2Delta strain have a reduced level of palmitoylation and are partially mislocalized to the vacuole. Based on these observations, we propose that Erf2 is a component of a previously uncharacterized Ras subcellular localization pathway. Putative members of an Erf2 family of proteins have been uncovered in yeast, plant, worm, insect, and mammalian genome databases, suggesting that Erf2 plays a role in Ras localization in all eucaryotes.

Acyltransferases↗