Biomedical subjects

X Guo

Publications and source records attributed to X Guo.

At least 127 records · Page 7Linked to original sources

PubMed2001

[Effect of inorganic arsenic on gap junctional intercellular communication between human skin fibroblasts].

OBJECTIVE: The aim of this study is to investigate the effect of inorganic arsenic on gap junctional intercellular communication (GJIC) between human skin fibroblasts. METHODS: GJIC between human skin fibroblasts was detected by the scrape loading/dye transfer assay. RESULTS: Arsenite at concentrations from 0.005 micromol/L to 5.0 micromol/L significantly inhibited the dye transfer between human skin fibroblasts in a dose dependent manner. The dye transfer between human skin fibroblasts was also inhibited by arsenate, while the dose-dependent effects were not observed. Further study found that arsenite at concentrations of 0.5 micromol/L and 5.0 micromol/L significantly increased protein kinase C (PKC) activities in cells, especially in the membrane fraction. CONCLUSIONS: Arsenite and arsenate significantly inhibited GJIC between human skin fibroblasts, suggesting that inorganic arsenic may play an important role in the process of tumor promotion. Furthermore, PKC activation may be involved in the mechanisms of GJIC inhibition by inorganic arsenic.

Arsenates↗

PubMed2001

[A clinical investigation on the relationship between nitric oxide and elevation of intraocular pressure in glaucoma].

OBJECTIVE: To investigate the role of nitric oxide (NO) in the process of intraocular pressure (IOP) elevation in glaucoma. METHODS: The levels of NO in plasma and in aqueous humor which were obtained from 16 patients with acute angle closure glaucoma (10 female, 6 male), 29 cases with cataract (13 female, 16 male) and 30 normal volunteers (13 female, 17 male) were detected by high performance liquid chromatography and expressed with the total NO(2) and NO(3). RESULTS: It was found that the mean level of NO in the plasma in glaucoma group was (l,390.78 +/- 302.95) ng/L that was significantly lower than that in the normal group (2 969.37 +/- 862.85) ng/L (t = 2.853, P < 0.01). But in cataract group it was (4,234.89 +/- 1,495.23) ng/L that was significantly higher than that in the normal group (t = 4.471, P < 0.01). There was no significant difference in the level of NO in the aqueous humor between glaucoma group (2,052.03 +/- 694.74) ng/L and normal group (1,405.83 +/- 602.70) ng/L (t = l.862, P > 0.05). But in cataract group the mean level of NO (2, 454.67 +/- 655.13) ng/L in the aqueous humor was increased remarkably in comparison with that in the normal group (t = 2.752, P < 0.01). The rate of the mean content of NO in normal aqueous humor and plasma (aqueous/plasma) was 47.3%, and that in cataract group, 57.96% (P > 0.05). But in glaucoma group, the rate was 144.0%. CONCLUSION: The content of nitric oxide in the plasma and aqueous humor is related to the elevation of IOP in cases with acute angle closure glaucoma.

Aged↗

PubMed2001

[Malignant transformation of monkey kidney epithelial cell induced by EBV BARF1 gene and TPA].

BACKGROUND: To study the effect of Epstein-Barr virus (EBV) BARF1 gene alone and synergistic effect of the gene and TPA in carcinogenesis. METHODS: PT1 and PT7 cell line which were immortalized monkey kidney epithelial cells induced by the BARF1 gene of EB virus.PT1 and PT7 cell were cultured with 5 ng/ml TPA for two weeks. Then the nude mice and scid mice were injected with PT1, PT7, PT1+TPA, PT7+TPA cells, respectively. RESULTS: The immortalized PT1 and PT7 cells could not develop the tumor in nude mice, but could develop the tumor in scid mice (severe combined immune deficiency mice). It took about 45-60 days for development of tumor. After adding the tumor promoter TPA, the PT1 and PT7 cells developed the tumor either in nude mice or scid mice. It needed about 20-22 days in nude mice and 5-7 days in scid mice for development of tumor. PCR amplification revealed EBV-BARF1 gene in tumor tissues. CONCLUSIONS: EB virus BARF1 gene is another oncogene. Malignant transformation of the primary monkey kidney epithelial cell can be induced with BARF1 gene,even without tumor promoter.

Animals↗

PubMed2001

[Experimental and clinical studies of recombinant human growth hormone treatement of hypoproteinemia of liver cirrhosis patients].

BACKGROUND: To assess the effect of recombinant human growth hormone (rhGH) therapy to liver cirrhosis patients with hypoproteinemia. METHODS: 31 liver cirrhosis patients were treated with rh GH (0.25 IU/kg/day-) and 20 such patients with human albumin (10 g/day) as control all for 10 days. Serum levels of growth hormone (GH), insulin-like growth factor (IGF)-1 and albumin (ALB) were measured by radio-immunoassay before 24h and after 24h and 10 days of rhGH therapy. Serum levels of GH and IGF-1 of 10 age matched healthy subjects were also measured. RESULTS: As compared with healthy subjects, the pretreatment serum GH level of liver cirrhosis patients was high (4.96 +/- 3.97 vs 1.62 +/- 2.26, P <0.05), and the IGF-1 level was markedly lower (36.53 +/- 12.77 vs 56.95 +/- 16.46, P <0.01). After 10 days of rhGH administration, the serum IGF-1 and ALB levels of the treated group increased significantly as compared with the control group (P <0.01). CONCLUSIONS: Exogenous rhGH therapy can overcome the GH resistance of liver cirrhosis patient s and can increase significantly the serum albumin level as compared with the control group who were treated with human albumin only.

Female↗

PubMed2001

Effect of buyang huanwu decoction on platelet activating factor content in arterial blood pre- and post-arterial thrombosis in rats.

To explore the effect of Buyang Huanwu Decoction (BHD) on platelet activating factor (PAF) content in arterial blood pre- and post-arterial thrombosis in rats, male Wistar rats were randomly divided into 3 groups, the medicine group treated with BHD, the control group with dexamethasone liquid, and the blank group with distilled water. Oral administration was given for 14 consecutive days, once daily. Model of arterial thrombosis was established in the animals 2 hours after final medication, the blood content of PAF, dry weight (DW) and occlusion time (OT) of thrombus, and dry weight of thrombus/body weight (TW/BW) ratio were observed. Results indicated that BHD could markedly lower the arterial blood content of PAF after thrombosis, increase the OT of thrombus, reduce the dry weight of thrombus and the TW/BW ratio (P < 0.05). It is suggested that BHD can inhibit the pathologic PAF metabolism and formation and development of arterial thrombus.

Animals↗

PubMed2001

[Influence of different collection time on yield and constituents of essential oil of herba pogostemonis from Gaoyao County].

The constituents of the volatile oil of Herba Pogostemonis from Gaoyao county collected at various different time by GC/MS combination technology were analysed and compared. The results showed that the average dry weight of single plant(i.e. yield) increased gradually from July to next April, the content of volatile oil was highest in November. The contents of pogostemone in the leaf oil were higher in July and September, then decreased gradually with growth time; pachouli alcohol was higher in September, October and November, lower in other months. The contents of pogostmone in stem oil were higher in July, October and next January, lowest in November. The content change of pachouli alcohol in stem oil were not obvious in all growth time, higher slightly only after November. Other compounds were not showed their variation law. So the quality of Herba Pogostemonis collected in November was higher if the content of volatile oil was used as a standard of quality evaluation, the result was in accordance with traditional collection experience.

Drugs, Chinese Herbal↗

PubMed2001

Bioactivity of bioresorbable osteosynthetic devices made of hydroxyapatite/poly-DL-lactide composites: an experimental study.

AIM: To investigate the bioactivity of the self-designed biodegradable osteosynthetic devices made of resorbable hydroxyapatite microparticles/poly-DL-lactide (HA/PDLLA) composites. METHOD: Forty-three rabbits with a transverse transcondylar osteotomy of the distal femur were fixed intramedullary by a HA/PDLLA rod, the duration of follow-up were 3, 6, 12, 24 and 36 weeks. Histological, scanning electron microscopic (SEM), energy dispersive X-ray (EDX) and biomechanical analyses were done. RESULTS: Active new bone formation and direct bone-bonding were seen at the bone-implant interface. Generous apatite crystals deposited and grew on the surface of the composites at 3 approximately 6 weeks postoperation. The interfacial shear strength increased significantly. CONCLUSION: Through the incorporating of resorbable HA microparticles, specific bone-bonding and active osteogenic capacity is introduced. This kind of bioactivity, together with other properties such as sufficient mechanical strength, enhanced biocompatibility and radiopacity, which are intrinsically unobtainable in totally resorbable polymer/polymer systems, make the HA/PDLLA composites become a desirable material for the internal fixation of cancellous bone.

Absorbable Implants↗

PubMed2001

[IR studies on hydrogen bonding in hard segment domains of segmented polyester polyurethaneurea].

Hydrogen bonding in hard segment domains of segmented polyester polyurethaneurea (PUU) based on 4,4'-diphenylmethane diisocyanate (MDI), ethylene diamine (ED) and polybutylene adipate (PBA) (M.W.1,975 and M.W.1,228) was studied by means of IR spectroscopy. It was found that the double peak absorption of urea C=O groups occurred in the studied PUU with the increase of hard segment content. Two hydrogen bonding models of urea C=O groups in different hard segment sequence lengths of PUU were proposed. Three dimensional hydrogen bonding in hard segment domains can be formed by further bonding of the above planar hydrogen bondings.

Hydrogen Bonding↗

PubMed2001

[IR studies on deuterated polyester polyurethaneurea elastomers].

Segmented polyester polyurethaneurea (PUU) based on 4,4'-disphenylmethane diisocyanate (MDI), ethylene diamine (ED) and polybutylene adipate (PBA) elastomers and their deuterated polymers were studied by means of IR spectroscopy. The results indicated that IR bands of hydrogen bonded N-H vibrations involved in PUU were greatly affected by deuteration. The bands which were sensitive to deuteration were those near 3,332, 3,190, 1,600, 1,539, 1,317, 1,257 and 1,230 cm-1, respectively. In addition, it was also found that PUU samples with different hard segment contents and polyester soft segment molecule weights were similarly affected by deuteration in degree.

Elasticity↗

PubMed2001

[IR studies on segmented polyester polyurethaneurea elastomers].

The studies segmented polyester polyurethaneurea (PUU) elastomers based on 4,4'-diphenylmethane diisocyanate (MDI), ethylene diamine (ED) and polybutylene adipate(PBA) (M.W.1,975 and M.W.1,228) were studied by means of IR spectrascopy. The major IR bands of PUU were first assigned and the views were proposed for the bands at 1,600, 1,317, 1,520 and 1,230 cm-1 assigned by other authors. The reliable theoretical basis for the assignments of IR bands and the studies of hydrogen bonding in these elastomers has been proposed by use of deuteration and varying temperature. The results indicated that substantial hydrogen bonding mainly occurred in the aggregate region of hard segments, a small amount of hydrogen bonding can be formed at the interface between the soft and hard segments. It can be concluded from this work that the studied PUU materials were phase segregation.

Elastomers↗

PubMed2000

On-line membrane extraction liquid chromatography for monitoring semi-volatile organics in aqueous matrices.

Membrane extraction is an attractive alternative to conventional extraction methods, such as liquid-liquid extraction and solid phase extraction, because the analytes can be isolated in a continuous fashion. On-line detection can be carried out using a suitable analytical instrument. The objective of this study is to study the enrichment of semi-volatile organic compounds (SVOCs) from an aqueous matrix by on-line membrane extraction, to be followed by liquid chromatographic (ME-LC) analysis for continuous monitoring. The membrane serves as an interface across which liquid-liquid extraction takes place. The SVOCs transfer from the aqueous phase and are concentrated in an organic extractant. The enriched solvent is intermittently injected into an HPLC for analysis. In this paper, the enrichment into the organic phase under different operating conditions and the performance characteristics of the instrumentation are presented.

Calibration↗

PubMed2000

Multiple scattering, parton energy loss, and modified fragmentation functions in deeply inelastic eA scattering

Modified quark fragmentation functions in deeply inelastic eA collisions and their QCD evolution equations are derived for the first time in the framework of multiple parton scattering. Induced radiation gives rise to additional terms in the evolution equations and thus softens the modified quark fragmentation functions. The results in the next-leading-twist depend on both diagonal and off-diagonal twist-four parton distributions and the combination of which clearly manifests the LPM interference pattern. The predicted modification depends quadratically on the nuclear size ( A2/3). Generalization to the case of hot QCD medium is also discussed.

Journal Article↗

PubMed2000

Surfactant protein genetic marker alleles identify a subgroup of tuberculosis in a Mexican population.

Pulmonary surfactant and its components are essential for normal lung function and are involved in local host defense. Surfactant protein (SP)-A and SP-D bind to and modulate phagocytosis of Mycobacterium tuberculosis by macrophages. Frequency comparisons of SP marker alleles in tuberculosis patients and healthy control subjects (tuberculin-skin test positive or general population) were performed. Regression analyses of the tuberculosis and the tuberculin-skin test positive groups revealed, on the basis of odds ratios, tuberculosis susceptibility (DA11_C and GATA_3) and protective (AAGG_2) marker alleles. Similarly, between tuberculosis patients and general population control subjects, susceptibility 1A(3), 6A(4), and B1013_A and protective AAGG_1, and AAGG_7 marker alleles were observed. Moreover, interactions were seen between alleles 6A(2) and 1A(3) (P=.0064) and between 1A(3) and B1013_A (P=. 036). The findings indicate a possible involvement of SP alleles in tuberculosis pathogenesis.

Adult↗

PubMed2000

Analysis of gene expression profile during 3T3-L1 preadipocyte differentiation.

Cellular differentiation is a process in which a group of differentiation specific genes is programmatically induced. This gene expression program leads to changes in both cellular morphological and physiological phenotypes. Using an 18,376-member cDNA/EST microarray, we analyzed the difference in gene expression profiles between differentiated 3T3-L1 adipocyte and non-differentiated 3T3-L1 preadipocyte. From our study a large number of genes and ESTs were identified as differentially induced or suppressed. In this paper we describe the changes of gene expression profile during 3T3-L1 cell differentiation.

3T3 Cells↗

PubMed2000

Delayed meiosis and polar body release in eggs of triploid Pacific oysters, Crassostrea gigas, in relation to tetraploid production.

The dynamics of polar body release are important for creating polyploid shellfish. For producing triploids, these dynamics concern meiosis in diploid eggs and are well understood. For creating tetraploids, eggs from triploids are employed and the dynamics, variation, and environmental influences upon polar body release are less studied. We investigated the effects of several agents on the timing of 50% first polar body (PB1) release in eggs of triploids. PB1 release is generally slower in triploid eggs than diploid ones at 26 degrees C. Lowering the temperature (from 26 to 19 degrees C) had a marked effect on timing of 50% PB1 in both diploid and triploid eggs. While lower temperature merely slowed development in diploid eggs, it nearly halted it in triploid eggs. At any temperature, the variability in 50% PB1 release was much higher in triploid eggs than diploid ones; this variation occurred both within eggs from individual females and among eggs from different females. The amount of time eggs remain in seawater between the time they are stripped and fertilized (or time of hydration) also affected rate of meiosis. In triploid eggs, the average time necessary for the expulsion of 50% PB1 was 23 min post-fertilization (PF) for 75 min of hydration versus 29 min PF for 35 min. However, increasing the time of hydration had no effect on the variability in the timing among females. Serotonin also had no effect on the dynamics of polar body release in triploids. Variability among triploid females in timing of meiosis cannot be improved with any treatments we tried. Consequently we recommend that treatments of triploid eggs to produce tetraploids incorporate a single female at a time.

Journal Article↗

PubMed2000

Universality in the nuclear dependence coefficient alpha(q(T))

We derive the nuclear dependence coefficient alpha(q(T)) for Drell-Yan and J/psi production. We show that at small q(T), alpha(q(T)) is given by a universal functional form: alpha(q(T)) = a+bq(2)(T), and the parameters a and b are completely determined by either perturbatively calculable or independently measurable quantities. This universal functional form alpha(q(T)) is insensitive to A, and is consistent with existing data.

Journal Article↗

PubMed2000

Unique biochemical, cytotoxic, and antitumor activity of camptothecin and 4beta-amino-4'-O-demethylepipodophyllotoxin conjugates.

Two compounds having a camptothecin (CPT) analog conjugated to the 4beta-amino-4'-O-demethylepipodophyllotoxin analog were evaluated for their biochemical and biological activities. W1[camptothecin-(para)-4beta-amino-4'-O-demethylepipodophyllotoxin] had no activity against topoisomerase II (TOP II), but inhibited topoisomerase I (TOP I) with an IC(50) value 2-fold higher than CPT. W2 [camptothecin-(ortho)-4beta-amino-4'-O-demethylepipodophyllotoxin] had inhibitory activity against TOP I and TOP II with IC(50) values 1.5-fold higher than either CPT or etoposide (VP-16). Both conjugates had similar cytotoxicity against the KB cell line, although the protein-linked DNA breaks (PLDBs) generated by W2 in KB cells were about 4-fold more than those of W1. No cross-resistance with the two conjugates was seen in a VP-16-resistant KB subline, which showed down-regulation of TOP II and overexpression of the multiple drug resistance-associated protein, or in a vincristine-resistant KB subline with overexpression of gp-170/mdr-1. The CPT-resistant KB variant (KB CPT 100), which has a reduction in TOP I content and another mechanism that occurs post-PLDB formation, was partially resistant to both compounds. W1 was not affected by this post-PLDB resistance mechanism. Cell cycle analysis demonstrated that W1 and W1 had similar cell cycle effects on KB and KB CPT 100 cells, which accumulated in S-phase upon drug treatment. These results suggested that W1 and W2 exerted their cytotoxicity through TOP I. In CPT-resistant cells, however, an unidentified target also may be involved in the cytotoxic action of W1 and TOP II may still be a target for W1. In vivo, W1 was more effective against the growth of human prostate cancer cells in nude mice than VP-16, CPT, or W2. Given its antitumor activity and unique biochemical mechanism of action, W1 warrants exploration as an antitumor compound.

Animals↗

PubMed2000

Elevation of serum vascular endothelial growth factor in male patients with metastatic nasopharyngeal carcinoma.

BACKGROUND: Angiogenesis is essential for tumor growth and metastasis. Vascular endothelial growth factor (VEGF) is the most potent angiogenic factor identified to date. The authors investigated the correlation between the levels of serum VEGF (S-VEGF) in patients with nasopharyngeal carcinoma (NPC) and disease progression. METHODS: The sera from 65 male patients with nonmetastatic NPC, 22 male patients with metastatic NPC, and 27 healthy male volunteers were obtained. A quantitative enzyme-linked immunosorbent assay was performed to measure the concentrations of S-VEGF in the sera. RESULTS: The mean S-VEGF levels were 371.0 pg/mL(-1) (range, 128.5-691.1 pg/mL(-1)) for healthy controls, 375.6 pg/mL(-1) (range, 72.9-1202.5 pg/mL(-1)) for patients with nonmetastatic NPC, and 958.6 pg/mL(-1) (range, 264.4-3744.9 pg/mL(-1)) for patients with metastatic NPC. The mean S-VEGF level in patients with metastatic NPC was significantly higher than in either patients with nonmetastatic NPC (P < 0.001) or healthy controls (P < 0.001). However, there was no statistical difference between these results for healthy controls and patients with nonmetastatic NPC. At the level of 900 pg/mL(-1), S-VEGF indicated distant dissemination of NPC with a specificity of 95.4%, a sensitivity of 31.8%, a positive predictive value of 70.0%, and a negative predictive value of 80.5%. No significant differences in the levels of S-VEGF were found among various T classifications, N classifications, and clinical stages of nonmetastatic NPC. CONCLUSIONS: The levels of S-VEGF were significantly elevated in male patients with metastatic NPC. These levels did not correlate with locoregional progression of NPC. The usefulness of detecting S-VEGF in the early diagnosis of NPC appears to be limited.

Adolescent↗