Search PubMed⌕ Search

Biomedical subjects

Y Guo

Publications and source records attributed to Y Guo.

At least 235 records · Page 13Linked to original sources

[Effect of reperfusion after local ischaemia on the M receptor density in rat brains].

OBJECTIVE: To study the dynamic changes in the density of muscarinic acetylcholine receptor in different areas of rat brains during reperfusion after local ischaemia. METHODS: The rat cerebral focal ischemia/reperfusion model after middle cerebral artery occlusion was made by the intraluminal suture method. Using 3H-QNB as radioligand, after binding with M receptor on the brain slice of the rat model, the brain samples were exposed on the hypersensitive film [H-3] to complete autoradiography, and the density of M receptor in different areas on the film of autoradiography was measured. RESULTS: There were no changes in the M receptor density in 2 hours' ischaemia group and 2 hours' reperfusion group, M receptor densities in the area of occipital cortex (OC) and temporal cortex (TC) were observed to decrease significantly in 8 hours' reperfusion group, but the degree of decrease was lower than 24 hours' and 72 hours' reperfusion groups, there was significant decrease in the density of M receptor in the areas of caudate putamen (CP), frontal cortex (FC), TC, OC of the 24 hours' and 72 hours' reperfusion groups and no difference was found between these two groups, and the imaging of M receptor in the domains with decreased receptor was obvious. CONCLUSIONS: The quantity of M receptor did not change right after ischaemia or reperfusion. It decreased gradually after an interval of time; Imaging of the M receptor could assess the changes of the density of viable cholinergic neurons and be a marker of diagnosis, therapy, and prognosis of brain ischaemia.

Animals↗

[Combined use of steroid hormone and low dose gossypol for antifertility and its mechanism in rats].

OBJECTIVE: To study the feasibility and the morphological mechanism of combined use of steroid hormone (methyltestosterone and ethinyl estradiol) and low dose gossypol for antifertility in adult Wistar rats. METHODS: We used methyltestosterone 20 mg/(kg.d), ethinyl estradiol 100 micrograms/(kg.d), and gossypol 12 mg/(kg.d) to feed male rats for 6 weeks via gastric intubation to induce infertility, then used gossypol 12 mg/(kg.d) alone for another 12 weeks to maintain infertility. Testicular sperm counts, cauda epididymal sperm motility, and sperm silver staining were used to determine infertility and morphology of sperm at the end of the two phases. Testicular morphology of the rats was observed from HE and PAS staining of paraffin sections. F1 generation of the rats would be examined in a series of behavioral tests after their 6-week recovery periods. RESULTS: There was no substantial change in testicular sperm counts of drugs-treated rats both for 6 weeks and 6 plus 12 weeks compared with that of control. But cauda epididymal sperm motility of drugs-treated rats went down to zero at the end of two phrases. The result of sperm silver staining showed that epididymal sperm were all deleterious of either segregation of sperm nucha from sperm head, or separation in annular granule of sperm tail. The observation of testicular morphology suggested that spermatogenesis is only partially affected. The ratios of stages II-III (9.3 +/- 3.4)% and stages IX-X (3.6 +/- 0.6)% were remarkably dropped, but that of stages IV-VI (36.7 +/- 5.0)% obviously ascended comparing with (26.8 +/- 1.7)%, (6.0 +/- 0.4)%, (24.5 +/- 2.7)% of control at the end of 6 plus 12 weeks. Moreover, no adverse effect was found in viscera tissue sections. CONCLUSIONS: Steroid hormone made the procedure of spermatogenesis slower and low dose gossypol caused all sperm lose their activity in epididymis. Both affect the process of spermatogenesis from different endpoints and successfully induce infertility in short term. Low dose gossypol not only executes its antifertility function in epididymis, but also affects the quality of spermatozoal production in testis by impacting the procedures of both acrosomal formation and spermatozoal elongation, so it can completely maintain infertility in long term. The infertility was reversible that the infertile rats can be recovery in about 6 weeks. Their F1 generation were proved to be normal through a set of behavioral tests.

Administration, Oral↗

[Male contraception of triptonide and its function mechanism].

OBJECTIVE: The male contraceptive mechanism in rats of triptonide, isolated from Multiglycosides of Tripterygium wilfordii (GTW), was investigated. METHODS: The dosage of triptonide was 200 micrograms/(kg.d), fed for 8 weeks via gastric intubation. Sperm counts, sperm motility, and sperm silver staining were used to test the antispermatogenic effect of triptonide; the study of morphology was learned from paraffin sections of testis and visceras of triptonide-treated rats; protamine was abstracted from testis by electrophoresis; using antisense mRNA of cyclin D1 and Cdk4 as prodes, we examined the expression of cyclin D1 and Cdk4 through hybridization in situ. RESULTS: Sperm counts (26.43 +/- 3.90) x 10(6)/g and sperm motility(66.0 +/- 6.8)% of triptonide-treated rats were substantially different from those of control, (41.15 +/- 5.51) x 10(6)/g (P < 0.01) and (88.0 +/- 2.0)% (P < 0.001). Paraffin sections of testis of triptonide-treated rats stained by PAS showed that the number of spermatids per 100 sertoli cells (9.15 +/- 0.33) was remarkably decreased compared with control's (10.73 +/- 0.38) (P < 0.001). At the same time, delaying sperm-released process was observed, which affects the nature course of sperm. And the extended vacuoles of vary sizes, the segregation of cells in lumens were also found in the cross-section of testis of rats treated with triptonide. In addition, the contents of protamine (4.6 +/- 2.2)% was extremely decreased, compared with the control's (40.6 +/- 7.2)% (P < 0.001). By using antisense mRNA of cyclin D1 and Cdk4 as prodes, we detected that the expression of the genes was notably increased in spermatids. CONCLUSIONS: The results suggest the antispermatogenic effect of triptonide is very well and it mainly plays its role on spermatids by increasing the expression of cyclin D1 and Cdk4, meanwhile, decreasing the biosynthesis of protamine. The appropriate target region of triptonide makes itself most potency to be a suitable male antifertility drug.

Animals↗

[Identification of early irreversible damage area in a rat model of cerebral ischemia and reperfusion].

OBJECTIVES: To observe the early neuron ischemic damage in focal cerebral ischemia/reperfusion with histostaining methods of argyrophil III (AG III), Toludine blue(TB), and H&E, and to make out the 'separating line' between the areas of reversible and irreversible early ischemic damage. METHODS: Forty-two male Wistar rats were randomly divided into the following groups: pseudo-surgical, blank-control, O2R0(occluded for 2 hours and reperfused for 0 hour), O2R0.5, O2R2, O2R4, O2R24. There were 6 rats in each group. Rats in experimental groups were suffered focal cerebral ischemia/reperfusion through a nylon suture method. After a special processor for tissue manage, the brain were coronal sectioned and stained with H&E, TB, and AG III. The area where dark neurons dwell in (ischemic core) were calculated with image analysis system. RESULTS: The success rate of ischemic model for this experiment is 90%. After being stained with argyrophil III method, normal neurons appear yellow or pale brown, which is hardly distinguished from the pale brown background. The ischemic neuron stained black, and has collapsed body and "corkscrew-like" axon or dentries, which were broken to some extent. The neuropil in the dark neurons dwelt area appears gray or pale black, which is apparently different from the pale brown neighborhood area. The distribution of dark neurons in cortex varies according to different layers, and has a character of columnar form. The dark neurons present as early as 2 hours ischemia without reperfusion with AG III method. CONCLUSIONS: AG III stain could selectively display early ischemic neurons, the area dwelt by dark neurons represent early ischemic core. Dark neuron is possibly the irreversibly damaged neuron. Identification of dark neurons could be helpful in the discrimination between early ischemic center and penumbra.

Animals↗

[A simplified six-item checklist for screening of fragile X syndrome].

OBJECTIVE: To investigate whether a simplified six-item checklist could be developed to improve the screening fragile X syndrome test result. METHODS: Nine clinical characteristics were selected from patient records of 190 male and 18 female pediatrics for fragile X screening test were analyzed. The characteristics included mental retardation, family history of mental retardation, elongated face, large or prominent ears, attention deficit hyperactivity disorder, Autistic-like behavior, simian crease, macroorchidism, and hyperextensible joints. RESULTS: Seven cases were diagnosed with fragile X syndrome by Southern analysis on PCR product. Among the nine characteristics, simian crease, macroorchidism, and hyperextensible joints were eliminated, because of low frequency and statistical insignificance. Using remaining six-item clinical checklist, if a score of 6 or more was used as the criteria for screening fragile X test, about 60% of this test in our cases could have been eliminated clinically without missing any positive cases. Thereby the proportion of case with positive results improved 8.8%. CONCLUSIONS: With our simplified six-item clinical checklist, 60% of testing could have been eliminated clinically, thereby improving the effectiveness of fragile X screening test and promoting the proportion of cases with positive results in two groups.

Adolescent↗

[Epidemiological characteristics of Guillain-Barré syndrome in urban and rural areas in Beijing and Hebei, China].

OBJECTIVE: To investigate epidemiological and clinical patterns of Guillain-Barré syndrome (GBS) in urban and rural areas in Beijing municipality and Hebei province, China. METHODS: We investigated GBS incidence using a strengthened case surveillance and an active case ascertainment in 2 counties and 4 districts of Beijing municipality and 3 counties of Hebei province during 1993 to 1994. RESULTS: On the basis of the diagnostic criteria of NINCDS, 54 patients were identified. The age-adjusted incidence rates per 100,000 population for GBS were 0.9 in rural areas, and 0.8 in urban areas. A peak agespecific incidence showed in adults aged 50 to 59 years. A higher incidence appeared to occur in the spring and summer for rural residents, but not significant for urban population. In comparing course of GBS in rural and urban areas, there were differences in mean days from beginning of neurological symptom to maximal weakness (4.3 vs 7.6 days), and from symptom onset to beginning of recession (11.8 vs 17.5 days). There were preceding events in 72% patients, most frequently in respiratory infection, sensory disturbance in 70.9%, and respiratory assistance in 7.6%. The outcome was compatible with other reports; with complete recovery at 12 months in 79.2% and minimal residua in 20.8% for those alive and with casefatality rate in 7.4%. In addition, a follow-up study on electrophysiological features in 19(90.5%) patients from two counties of Beijing showed the demyelinating lesion (89.5%) over the axonal lesion (52.6%) of motor and/or sensory nerves. CONCLUSIONS: The epidemiological and clinical characteristics of GBS were similar to that reported in other countries. Demyelinating GBS was the main pattern in present population-based study.

Adolescent↗

[Dynamic penumbra in a rat model of focal cerebral ischemia and reperfusion].

OBJECTIVES: To identify the ischemic core and penumbra of variant ischemia and reperfusion period by the dark neuron method, observe them dynamically, and elicit the morphological character of ischemic pneumbra. METHODS: Total 72 male Wistar rats were randomly divided into the following groups: pseudo-surgical, blank-control, O24R0 (sustained ischemia for 24 hours), O4R24(ischemia for 4 hours and reperfused for 24 hours, the following may be deduced by analogy), O2R0, O2R0. 5, O2R2, O2R4, O2R8, O2R24, O2R48, O2R96. There were 6 rats in each group. Rats in experimental groups were suffered focal cerebral ischemia-reperfusion through a nylon suture method. After perfusion fixed, the brains were coronal sectioned and stained with HE, TB and acetum plumbi/silver nitrate. Sections were observed with light microscope and electron microscope. The area of ischemic core and penumbra was measured and analyzed with an image analysis system. RESULTS: The penumbra expanded rapidly in a short period after reperfusion, and reach its apex when reperfused for 2 hours (P < 0.05). The penumbra was relatively stable during 4 to 48 hours reperfusion. There were many cell types in ischemic core and penumbra, the proportion of cells changed according to reperfusion time. CONCLUSIONS: Reperfusion could aggravate cerebral edema and make the ischemic penumbra to expand during the first hours.

Animals↗

[Effect of Tripterygium Wilfordii Hook T4 monomer on proliferation and interleukin-6 production of synovial fibroblasts of patients with rheumatoid arthritis].

OBJECTIVE: Tripterygium Wilfordii Hook multi-glycosides T2 has been wildly used in China in treatment of RA. T4 was abstracted from T2 and was reported much more efficient in anti-inflammatory and immune suppression than T2. This study was to investigate the effect Tripterygium Wilfordii Hook T4 monomer on proliferation and interleukin-6 production of synovial fibroblasts of patients with rheumatoid arthritis. METHODS: Synovium was obtained from patients with rheumatoid arthritis undergoing synovectomies or joint replacement. Cultures of synovial fibroblasts were established. After 3 generations, cultured synovial fibroblasts were stimulated with IL-1. Then 1.5 ng/ml, 5 ng/ml and 15 ng/ml T4 were added, and synovial fibroblasts were cultured in the presence of T4 for 48 hours. Cell proliferation was assayed using MTT method. IL-6 level of supernatant was measured by ELISA. RESULTS: Proliferation of synovial fibroblasts was inhibited by T4. The proliferation inhibition effect of T4 was dose dependent and inhibition rate was 5.18%, 10.95% and 21.37%, respectively. And T4 had no effect on IL-6 production by IL-1 stimulated synovial fibroblasts. CONCLUSIONS: T4 might control the disease activity of RA by inhibiting the proliferation of synoviocyte. And T4 might not influence the concentration of IL-6 in synovial fluid, as a central effect, since IL-6 has protective effect on articular cartilage.

Anti-Inflammatory Agents, Non-Steroidal↗

Role of sphingosine kinase in Ca(2+) signalling by epidermal growth factor receptor.

Contribution of sphingosine kinase (SPK)-catalyzed production of sphingosine-1-phosphate (SPP), in comparison to phospholipase C (PLC), to Ca(2+) signalling by epidermal growth factor (EGF) was studied in two HEK-293 cell clones (HEK2 and HEK3), expressing functional EGF receptors and exhibiting release of stored Ca(2+) by intracellular SPP. In HEK3 cells, EGF increased [Ca(2+)](i) and stimulated both, SPK and PLC. [Ca(2+)](i) increase, but not PLC stimulation, was strongly reduced by SPK inhibition. In HEK2 cells, EGF similarly stimulated PLC, but did not increase [Ca(2+)](i) or stimulate SPK, suggesting that intracellular SPP production plays a major role for Ca(2+) signalling by EGF in HEK-293 cells.

Calcium Signaling↗

Improved immunogenicity of a core-coated tetanus toxoid delivery system.

A new microparticulate delivery system composed of a stabilizing gelatin/poloxamer microcore surrounded by a PLGA coat was designed to improve the stability of tetanus toxoid (TT) encapsulated in PLGA microspheres. Microcores were prepared by a spray-congealing technique and encapsulated within PLGA using an oil-in-oil (o/o) solvent evaporation technique. SEM analysis of the cross-sections of the microcapsules revealed the adequate encapsulation of the cores, showing an intimate contact between the core and the coating. This structure was responsible for an osmotic phenomenon observed in vitro, which led to the release of the encapsulated TT in a short period of time. Nevertheless, it was observed that the release was affected by the presence of the poloxamer in the core: microspheres without poloxamer in the core exhibit a faster release (2 h) than those that incorporate the surfactant (24 h). The in vivo evaluation of this system showed that the encapsulated toxoid induced a low but continuous levels of neutralizing antibodies (Nt), whereas those obtained for the control (aluminum phosphate-adsorbed toxoid) decreased after reaching the maximum level at 14 weeks. Moreover, the administration of a mixture of encapsulated and adsorbed TT led to significant higher and more prolonged Nt levels than those measured for the adsorbed toxoid.

Animals↗

The mitogen-inducible Fn14 gene encodes a type I transmembrane protein that modulates fibroblast adhesion and migration.

The binding of polypeptide growth factors to their appropriate cell surface transmembrane receptors triggers numerous biochemical responses, including the transcriptional activation of specific genes. We have used a differential display approach to identify fibroblast growth factor-1-inducible genes in murine NIH 3T3 cells. Here, we report that the fibroblast growth factor-inducible-14 (Fn14) gene is a growth factor-regulated, immediate-early response gene expressed in a developmental stage- and adult tissue-specific manner in vivo. This gene, located on mouse chromosome 17, is predicted to encode an 129-amino acid type Ia membrane protein with no significant sequence similarity to any known protein. We have used two experimental approaches, direct fluorescence microscopy and immunoprecipitation analysis of biotinylated cell surface proteins, to demonstrate that Fn14 is located on the plasma membrane. To examine the biological consequences of constitutive Fn14 expression, we isolated NIH 3T3 cell lines expressing variable levels of epitope-tagged Fn14 and analyzed their phenotypic properties in vitro. These experiments revealed that Fn14 expression decreased cellular adhesion to the extracellular matrix proteins fibronectin and vitronectin and also reduced serum-stimulated cell growth and migration. These results indicate that Fn14 is a novel plasma membrane-spanning molecule that may play a role in cell-matrix interactions.

3T3 Cells↗

Drosophila presenilin is required for neuronal differentiation and affects notch subcellular localization and signaling.

Presenilins are a highly conserved family of proteins first identified as causative genes in early onset familial Alzheimer's disease. Recent studies have suggested a role for presenilins in the Notch-signaling pathway, but their specific function within this pathway remains unclear. Here, we have characterized the Drosophila presenilin gene and protein and studied their interaction with Notch in both mutants and transgenics. We find that the Drosophila presenilin protein is proteolytically cleaved and broadly expressed during development with the highest levels in neurons within the larval CNS. We also show that mutations in Drosophila presenilin (Dps) genetically interact with Notch and result in an early pupal-lethal phenotype characterized by defects in eye and wing development and incomplete neuronal differentiation within the larval CNS. Moreover, we find that processing of Notch in the Golgi by the furin protease is unaffected in Dps mutants and that Notch is present and may even accumulate on the plasma membrane of neuroblasts in the larval CNS of Dps mutants. In contrast, overexpression of Dps in transgenics causes Notch to accumulate in the cytoplasm. Taken together, these results indicate that Drosophila presenilin is required for proper neuronal differentiation and may regulate the subcellular localization of Notch proteins within cells, necessary for their accumulation and subsequent signaling capabilities.

Animals↗

[The complete nucleotide sequences of A/Goose/Guangdong/2/96(H5N1) virus RNA segment 1-3 and 5].

OBJECTIVE: To determine the nucleotide and amino acid sequences of PB2, PB1, PA and NP genes and compared them with sequences of A/HK/156/97(H5N1) virus for revealing the relationship between A/Googs/Guangdong/2/96(H5N1) and A/HK/156/97(H5N1) viruses. METHODS: Virion RNA was transcribed into cDNA by reverse transcriptase, cDNA amplified by PCR, the productions of PCR were purified. Afterward, RNA sequence analysis was performed by the dideoxynucleotide chain termination method, using synthetic oligodeoxynucleotide primers. RESULTS: The lengths of A/Goose/Guangdong/2/96(H5N1) virus RNA segment 1-3 and 5 contain 2,341, 2,341, 2,233 and 1,565 nucleotides, respectively. They encode for PB2 (759 amino acids), PB1 (757 amino acids), PA (716 amino acids) and NP (498 amino acids) proteins. The homologies of amino acid sequences of PB2, PB1, PA and NP proteins between A/Goose/Guangdong/2/96 (H5N1) and A/HK/156/97 (H5N1) virus are 96.4%, 97.2%, 97.3% and 97.0%, respectively. CONCLUSION: The lengths of RNA segment 1-3 and 5 of Goose strain are 2,341, 2,341, 2,233 and 1,565 nucleotides, respectively. The nucleotide sequences of these genes are distinguish able from those of Hong Kong virus.

Amino Acid Sequence↗

[Hepatitis B virus core promoter mutations in patients with fulminant hepatitis].

OBJECTIVE: To detect hepatitis B virus core promoter (CP) mutations in patients with fulminant hepatitis. METHODS: Polymerase chain reaction amplified serum HBV DNA fragments were directly sequenced. RESULTS: There were 2-12 nucleotide substitutions in CP region in the 7 subacute fulminant hepatitis patients studied. An 11 bp nucleotides insertion was found in one patient. Mutations in CP were usually seen in the first and the second A T rich regions. The A to T mutation at nt 1,762 and G to A mutation at nt 1,764 were found in 4 cases, 3 of them were HBeAg negative. The third A T rich region was kept intact in all the 7 patients, so did the initial site of HBV replication (DR1) and the initial site of mRNA transcription (1,783/1784 or 1,790 +/- 1 for precore mRNA and 1818 for pregenome-C/P mRNA). CONCLUSION: CP mutations in patients with fulminant hepatitis are common, most of the CP variations occur in the first and the second A T rich regions, and these mutations may impede the transcription of precore mRNA and affect the expression of HBeAg.

Amino Acid Sequence↗

[Preparation and identification of anti-fumonisin B1 monoclonal antibody].

Spleen cells from Balb/c mice immunized with an artificially KLH-glutaraldehyde fumonisin B1(FB1) conjugate were fused with murine Sp2/0 myeloma cells. One hybridoma cell line secreting monoclonal antibody against FB1 was established after the fusion cells subcloned for 4 cycles. This antibody was designated as FB(1)4G4. The titer of the antibody from ascites was 1:1 x 10(7).

Animals↗

The late phase of ischemic preconditioning is abrogated by targeted disruption of the inducible NO synthase gene.

The goal of this study was to interrogate the role of inducible NO synthase (iNOS) in the late phase of ischemic preconditioning (PC) in vivo. A total of 321 mice were used. Wild-type mice preconditioned 24 h earlier with six cycles of 4-min coronary occlusion/4-min reperfusion exhibited a significant (P < 0.05) increase in myocardial iNOS protein content, iNOS activity (assessed as calcium-independent L-citrulline formation), and nitrite + nitrate tissue levels. In contrast, endothelial NOS protein content and calcium-dependent NOS activity remained unchanged. No immunoreactive neuronal NOS was detected. When wild-type mice were preconditioned 24 h earlier with six 4-min occlusion/4-min reperfusion cycles, the size of the infarcts produced by a 30-min coronary occlusion followed by 24 h of reperfusion was reduced markedly (by 67%; P < 0.05) compared with sham-preconditioned controls, indicating a late PC effect. In contrast, when mice homozygous for a null iNOS allele were preconditioned 24 h earlier with the same protocol, infarct size was not reduced. Disruption of the iNOS gene had no effect on early PC or on infarct size in the absence of PC. These results demonstrate that (i) the late phase of ischemic PC is associated with selective up-regulation of iNOS, and (ii) targeted disruption of the iNOS gene completely abrogates the infarct-sparing effect of late PC (but not of early PC), providing unequivocal molecular genetic evidence for an obligatory role of iNOS in the cardioprotection afforded by the late phase of ischemic PC. Thus, this study identifies a specific protein that mediates late PC in vivo.

Animals↗

Subsurface tumor progression investigated by noninvasive optical second harmonic tomography.

Nonlinear optical imaging with femtosecond (10(-15)-second) laser technology was used to evaluate the subsurface tumor progression in control, dysplasia, and cancerous 7, 12-dimethylbenz[a]anthracene-treated hamster cheek pouch mucosa tissues. Two-dimensional images of hamster cheek pouch mucosa tissues were obtained by scanning the second harmonic signal at various sagittal and axial positions. The spatial mapping of the second harmonic signals showed depth differentiation between normal, dysplasia, and a more advanced cancerous state. This nonlinear optical method offers a noninvasive in situ imaging tool to the medical community.

9,10-Dimethyl-1,2-benzanthracene↗

Differential expression of PSP94 in rat prostate lobes as demonstrated by an antibody against recombinant GST-PSP94.

Prostate secretory protein (PSP94, 94 amino acids) is one of the most abundant proteins secreted from the prostate. Its biological role is unknown and still controversial, although it is assumed to have the potential to be a biomarker and a suppressor of prostate cancer. In order to establish an animal model to further elucidate its biological role, we expressed the mature form of rat PSP94 in Escherichia coli, using a glutathione S-transferase (GST) fusion expression vector; we generated a polyclonal rabbit antibody against the recombinant protein. The antibody specifically recognized recombinant rat PSP94 and cross-reacted only very weakly with its human homologue. Using the characterized anti-rat PSP94 antibody, we found that PSP94 was located primarily in rat prostate. Furthermore, PSP94 is present at different levels in different lobes of rat prostate, with significant levels detectable only in the lateral lobe (LP). In addition, the most abundant PSP94 expression was found in the prostate lobe secretions, and PSP94 levels in LP secretions were at least seven times higher than in secretions from the dorsal prostate (DP). The rat ventral prostate (VP) and other regions of the male accessory glands were found to be almost completely devoid of PSP94. Since most rat prostate dysplasia induced by steroid hormone treatment occurs only in dorsolateral prostate, prostate tissue-specific expression and the expression of PSP94 in dorsolateral, but not other, lobes of the prostate suggest a potential role in prostate targeting and prostate cancer development.

Animals↗