Biomedical subjects

Xun Xu

Publications and source records attributed to Xun Xu.

46 records · Page 3Linked to original sources

PubMed2002

Exogenous advanced glycosylation end products induce diabetes-like vascular dysfunction in normal rats: a factor in diabetic retinopathy.

BACKGROUND: Diabetic retinopathy has been shown to be directly associated with the degree and duration of hyperglycemia, and advanced glycosylation end products (AGEs) have been implicated in this pathological process. The purpose of the experiments reported here was to study the effect of AGE deposition on retinal vascular damage which leads to diabetic retinopathy. METHODS: Intravenous injection of exogenous AGEs was used to treat wild-type non-diabetic Sprague-Dawley rats. One of the two retinal slides from each animal was treated using immunohistochemical staining to label retinal vascular AGE deposition, the other H&E staining for counting of capillary pericytes. The results were compared with the findings in untreated wild-type and diabetic controls and in rats treated with unmodified rat serum albumin (RSA). RESULTS: After 2 weeks of continuous treatment, AGEs were identified in the retinal vascular tissue of the AGE-RSA-injected group. The average number of retinal capillary pericytes per 10x100 microscope power field was 4.313+/-0.34 (mean +/- SD) in the AGE-RSA-injected group, compared with 5.798+/-0.481 in the control group ( P<0.01). CONCLUSION: These experiments demonstrate that AGEs, independent of other metabolic factors, can induce vascular change resembling that of diabetic retinopathy.

Animals↗

PubMed2002

Genomic instability of prawn white spot bacilliform virus (WSBV) and its association to virus virulence.

Prawn White Spot Bacilliform Virus (WSBV) is a major pathogen that causes prawn diseases. In this study, we examined the sequence of WSBV genome DNA in the shrimp Penaeus japonicus, P. vannamei, P. Monodon, P. chinensis and Metapenaeus ensis through successive PCR amplification of the DNA fragments in the whole WSBV genome. We found a sequence deletion hotspot in the WSBV genome that is 305107 bp in length. The sizes of the deleted fragments were 4.6, 4.8 or 8.1 kbp depending on the species of prawn. Since the mortality of shrimp infected by the intact WSBV was always significantly higher than that of shrimp infected by DNA fragment-deleted WSBV, we suggest that this deletion be somehow linked to the virulence of the virus itself. This result may lead to the discovery of the molecular mechanism of the pathogenicity of WSBV in shrimps.

Animals↗

PubMed2002

Proteomic analysis of shrimp white spot syndrome viral proteins and characterization of a novel envelope protein VP466.

White spot syndrome virus (WSSV) is at present one of the major pathogens in shrimp culture worldwide. The complete genome of this virus has been sequenced recently. To identify the structural and functional proteins of WSSV, the purified virions were separated by SDS-PAGE. Twenty-four protein bands were excised, in-gel digested with trypsin, and subjected to matrix-assisted laser desorption ionization-time of flight mass spectrometry and electrospray ionization tandem mass spectrometry, respectively. Eighteen proteins matching the open reading frames of WSSV genome were identified. Except for three known structural proteins and collagen, the functions of the remaining 14 proteins were unknown. Temporal analysis revealed that all the genes were transcribed in the late stage of WSSV infection except for vp121. Of the newly identified proteins, VP466 (derived from band 16) was further characterized. The cDNA encoding VP466 was expressed in Escherichia coli as a glutathione S-transferase (GST) fusion protein. Specific antibody was generated with the purified GST-VP466 fusion protein. Western blot showed that the mouse anti-GST-VP466 antibody bound specifically to a 51-kDa protein of WSSV. Immunogold labeling revealed that VP466 protein is a component of the viral envelope. Results in this investigation thus proved the effectiveness of proteomic approaches for discovering new proteins of WSSV.

Amino Acid Sequence↗

PubMed2002

Characterization of a novel envelope protein (VP281) of shrimp white spot syndrome virus by mass spectrometry.

The primary structure of a novel envelope protein from shrimp white spot syndrome virus (WSSV) was characterized using a combination of SDS-PAGE and mass spectrometry. The resulting amino acid sequence matched an open reading frame (ORF), ORF1050, of the WSSV genome ORF database. ORF1050 contained 843 nt, encoding 281 aa, and was termed the vp281 gene. Computer-assisted analysis showed that both the vp281 gene and its product shared no significant homology with other known viruses. However, they shared striking identity/similarity with another WSSV structural protein, VP292, at both the nucleotide and amino acid sequence level, suggesting that vp281 and vp292 might have evolved by gene duplication from a common ancestral gene. WSSV VP281 cDNA was cloned into a pET32a(+) expression vector containing a T7 RNA polymerase promoter to produce (His)(6)-tagged fusion proteins in Escherichia coli strain BL21. Specific mouse antibodies were raised using the purified fusion protein (His)(6)-VP281. Western blot analysis showed that the mouse anti-(His)(6)-VP281 antibodies bound specifically to VP281 of WSSV, without cross-reactivity with VP292. The transmission electron microscope immunogold-labelling method was used to localize VP281 in the WSSV virion as an envelope protein. The cell attachment 'Arg-Gly-Asp' motif in VP281 indicated that this protein might play an important role in mediating WSSV infectivity.

Amino Acid Sequence↗

PubMed2002

Transcription and identification of an envelope protein gene (p22) from shrimp white spot syndrome virus.

White spot syndrome virus (WSSV) is one of the most virulent pathogens causing high mortality in shrimp. In the present study, an open reading frame (termed the p22 gene) was revealed from a WSSV cDNA library. The gene was expressed as a fusion protein with glutathione S-transferase (GST) in Escherichia coli and purified. Specific antibody was raised using the purified fusion protein (GST-P22). Temporal analysis showed that the p22 gene was a late gene. After binding between purified WSSV virions and anti-GST-P22 IgG followed by labelling with gold-labelled secondary antibody, the gold particles, under a transmission electron microscope, could be found along the outer envelope of WSSV virions. This experiment suggests that the p22 gene encodes an envelope protein of the virus.

Amino Acid Sequence↗

PubMed2002

Identification and localization of a prawn white spot syndrome virus gene that encodes an envelope protein.

Among the important challenges to shrimp aquaculture worldwide are the diseases caused by viruses, in particular by white spot syndrome virus (WSSV), which has a genome estimated to contain 305 kb. By analysis and comparison of the WSSV genomic DNA and cDNA libraries, an ORF (vp28 gene) was identified. The gene, encoding a novel 204-amino-acid protein, was expressed in Escherichia coli and purified. A specific antibody was raised using the purified VP28 protein. After inoculation of healthy adult Penaeus monodon shrimp with WSSV, the gene transcript and VP28 protein were first detected at low levels at 6 and 18 h post-infection, respectively. These experiments suggest that it might be a late gene. Immuno-electron microscopy with gold-labelled antibody revealed that the gold particles were distributed in the outer envelope of WSSV virions and showed that vp28 encodes a virus envelope protein.

Amino Acid Sequence↗

PubMed2002

[Surgical therapeutic results of rhegmatogenous retinal detachment associated with choroidal detachment].

OBJECTIVE: To evaluate the effect of different factors on the prognosis of rhegmatogenous retinal detachment (RRD) associated with choroidal detachment (ChD). METHODS: One hundred and eighty-eight eyes of 188 patients were studied retrospectively from Jan, 1996 to Aug, 1998. The clinical data, surgical management and follow-up records were analyzed. RESULTS: The total successful rate of the surgery was 83.0%, lower than that of general RRD. In the eyes with proliferative vitreoretinopathy (PVR) A-B, the rate was 89.6%, in the eyes with C(1)-C(3) PVR, the rate was 84.1%, in D(1)-D(3), 69.0%. In eyes with severe PVR the successful rate of vitrectomy was higher than that of scleral buckling alone. Administration of steroids before surgery resulted in high successful rate, but the length of time of the steroid treatment had no effect on the successful rate. In the eyes using scleral buckling alone, the drainage or without the drainage of subretinal fluid had no effect on the successful rate. CONCLUSIONS: RRD associated with ChD has worse prognosis than general RRD. The administration of steroids before surgery is necessary, and the timing of surgery is also important. In eyes with light PVR and ChD, scleral buckling without drainage of subretinal fluid is the first choice, but in eyes with severe PVR and ChD, vitrectomy is a better choice.

Adolescent↗

PubMed2002

[Long-term outcome of gfp gene modified human RPE xenografts into the subretinal space of rabbits].

The possibility of delivery genes to retina by using retinal pigment epithelium (RPE) transplantation was investigated. Cultured human adult RPE cells were transfected with retrovirus encoding green fluorescent protein (GFP), then GFP-expressing RPE cells were transplanted into the subretinal space of rabbits through pars plana vitrectomy under microscopy. The transplant sites were examined in vivo by ophthalmoscope for fluorescence. The animals were euthanatized at 1, 2, 3, 4, 6, 10, 11, 14, 18, 20, 23, 24, 25, 33, 54 weeks, respectively, and the retinas were studied histologically, including epi-fluorescent microscopy, confocal microscopy and transmission electron microscopy. The GFP-expressing transplant could be followed in the living retina up to 21 days by ophthalmoscope. The epi-fluorescent microscopy examination disclosed survival of the transplanted cells in 1 year with continual and significant GFP expression. It was observed the transplanted hRPE-gfp cells were not only present at transplant sites but spread over two to three quarters of retina. Generally, RPE xenografts integrated individually into host RPE in a regular cobblestones arrangement or formed a monolayer sheet between host RPE and neural retina. It was observed that intravitreal injection of FK-506 weekly improved the survival of RPE xenografts and reduced the infiltration of mononuclear microphages and lymphocytes in choroids from 1 through 14 weeks after transplantation. The results demonstrate a long-term survival of gene modified human RPE xenografts into the subretinal space of rabbits and support the feasibility of this approach for delivery genes to retina.

Adult↗

PubMed2002

[Epidemiology survey of rhegmatogenous retinal detachment in Beijing districts, Shanghai].

OBJECTIVE: To investigate the recent incidence and related risk factors of rhegmatogenous retinal detachment (RD) in Chinese people. METHODS: This incidence survey was based on 108 132 persons in Beijing districts, Shanghai, P. R. China. Rhegmatogenous RD patients came from inpatient, outpatient service data and the local health net databank composed of health data of 97.5% of all local residents. A contrast group was set up. The previous population data can be used to estimate the whole and specific incidence of rhegmatogenous RD. Some factors relevant to rhegmatogenous RD incidence were found by comparing the patient group and the contrast group. RESULTS: In Dec 1996 to Dec 1999, 61 cases with rhegmatogenous RD newly happened. The patients were 29 males and 32 females. The annual incidences of rhegmatogenous RD in these 4 years were 11.3/10(5), 14.1/10(5), 14.1/10(5) and 17.6/10(5) respectively, and the average annual incidence was 14.4/10(5) (95% confidence interval 10.0 - 18.6). There was a high incidence of rhegmatogenous RD in persons older than 40 years, especially between 40 and 59. When compared with the contrast group, the proportion of high myopia (more than -6.00 D) was significantly higher in rhegmatogenous RD patients group (P < 0.001). CONCLUSIONS: The annual incidence of rhegmatogenous RD of local Chinese population in these 4 years is increasing. It is strongly associated with high myopia and age, but not with gender.

Adolescent↗

PubMed2002

[An epidemiological survey of low vision and blindness of senile persons in Beixinjing blocks, Shanghai].

OBJECTIVE: To investigate the morbidities of low vision and blindness and the leading cause of blindness in residents aged >or= 60 years in Beixinjing blocks, Shanghai. METHODS: The vision archives were first established for total old residents. The pinhole visual acuity was recorded and classified under WHO grading system. Assigned ophthalmologic doctors assured the leading blind causes of every blind person. RESULTS: The response rates in 1994, 1997 and 2000 were 83.87%, 88.32% and 91.98% respectively. The morbidities of low vision and blindness in these 3 years were 3.61% and 1.51%, 2.31% and 1.09%, 1.31% and 0.71% respectively. The leading causes of blindness were degenerative retinopathy (including age-related maculopathy), cataract, corneal diseases and retinal angiopathy (including hypertensive and diabetic retinopathy, retinal artery or venous occlusion, etc). CONCLUSIONS: The morbidities of low vision and blindness in this area decreased from 1994. The leading cause of blindness was degenerative retinopathy.

Aged↗