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Biomedical subjects

Hong Yan

Publications and source records attributed to Hong Yan.

At least 37 records · Page 2Linked to original sources
PubMed2006

[Epidemiological features of spontaneous abortion among reproductive Tibetan women living at high altitudes areas].

OBJECTIVE: To study the status of spontaneous abortion among reproductive Tibetan women aged 15 - 49 years. METHODS: A cross-sectional survey was conducted on reproductive history of Tibetan women and the sample was chosen under the stratified multistage cluster random sampling technique. RESULTS: A total number of 3741 women were studied with a total number of 10,245 pregnancies. There were 386 spontaneous abortions reported with an incidence rate of 3.9%. Women living in the urban area had a higher rate than living in the rural areas. Women living in area where altitudes were above 4500 m, had a 2-time risk of having spontaneous abortion than those living in areas below 3500 m. The risk of having spontaneous abortion increased among women aged > or = 35 and those with more than 3 pregnancies. CONCLUSIONS: High altitude could contribute to the increase of spontaneous abortions incidence, suggesting that improvement of maternal care and nutrition and reduction of the frequency of pregnancy had important roles to play in reducing the incidence of spontaneous abortion among Tibetan women. Despite the fact that retrospective study on reproductive history could underestimate the incidence of spontaneous abortion, the incidence rate among Tibetan women might not be much higher than women living in the lowland areas.

Abortion, Spontaneous↗
PubMed2006

[Effects of nitrogen application rate and its basal-/top-dressing ratio on spatio-temporal variations of soil NO3- -N and NH4+ -N contents].

Under high-yielding cultivation condition, this paper studied the spatiotemporal variations of soil NO3 -N and NH4+ -N contents as affected by different nitrogen application rate and its basal-/top-dressing ratio, and calculated the apparent budget of soil nitrogen at different growth stages of wheat. The results indicated that compared with split application, applying all fertilizer nitrogen at jointing stage decreased the soil NO3- -N content and apparent surplus of soil nitrogen before jointing stage, and decreased the nitrogen leaching to deeper soil layers. Applying fertilizer nitrogen at flagging stage had no significant difference with split application in soil NO3- -N content, but increased soil NH4+ -N content. Applying fertilizer nitrogen at maturing stage increased the soil NO3- -N content in 0-60 cm and 0-20 cm layers. In comparing with applying 240 kg x hm(-2) of fertilizer nitrogen at jointing stage, applying 168 kg x hm(-2) of fertilizer nitrogen at the same stage decreased the soil NO3- -N and NH4+ -N contents at flagging stage, soil nitrogen deficit from flagging to maturing stage, and soil NO3- -N content at maturing stage. The grain yield and its protein content had no significant difference among different treatments, but applying all 168 kg x hm(-2) fertilizer nitrogen at jointing stage induced the highest grain protein content.

Fertilizers↗
PubMed2006

[Study on the influence of hypoxia induced microtubule damage on the opening of mitochondrial permeable transition pore of cardiac myocytes in rat].

OBJECTIVE: To investigate the influence of hypoxia induced microtubule damage on the opening of mitochondrial permeable transition pore (MPTP)of cardiac myocytes and on the decrease of respiratory function in rat. METHODS: Primary cultured myocardial cells from 30 neonatal rats were randomized as normoxic group (A), hypoxia group (B), normoxia with microtubule destabilizing agent group (C, with treatment of 8 micromol/L colchicines for 30 minutes before normoxia), and hypoxia with microtubule stabilizing agent group (D, with treatment of 10 micromol/L taxol for 30 minutes before hypoxia). beta-tubulin immunofluorescence ,the opening of mitochondria permeability transition pore, and the mitochondrial inner membrane potential were detected at 0.5, 1, 3, 6 and 12 post-treatment hours (PTH), and the mitochondrial respiratory function was determined by MTT method. The changes in these indices were also determined in A group at the corresponding time-points. RESULTS: Obvious damage of polymerized microtubule, opening of MPTP, mitochondrial inner membrane potential loss and decrease of myocardial respiratory activity were observed in both group B and C at 0.5 PTH, and they became more and more serious afterwards. However, the changes in the above indices in D group were much better than those in B group (P < 0.05 or 0.01), and no difference was found between D (92.8 +/- 4.0)% and C [(100.0 +/- 0.0) %, P > 0.05] groups. CONCLUSION: Hypoxia played a role in the myocardial microtubule damage as well as in the opening of MPTP. Moreover, hypoxia could also impair the mitochondrial respiratory function. Microtubule destabilizing agent could reproduce well the process of hypoxia induced microtubule damage, while the stabilizing agent exerted protective effect by improving the transition of mitochondrial permeability and the mitochondria respiratory function.

Animals↗
PubMed2006

[Preventive effect of carnosine on cataract development].

Carnosine (beta-alanyl-L-histidine) was the first and the simplest example of active peptides (actually a dipeptide). The anti-ageing effect of carnosine had been demonstrated in many studies in vivo and in vitro. More recently,there were some studies verifying the effect of carnosine on preventing cataract development. The molecular mechanisms are largely undetermined. The effect of carnosine on delaying the cataract formation may be through anti-glycation of protein, antioxidative impairment, protection protein against cross-links and DNA damage. Further study of carnosine on its biological features and the mechanisms of delaying the progression of cataractogenesis may provide a new therapy for preventing cataract.

Animals↗
PubMed2006

[Preventive effect of estrogen on cataract development].

A number of epidemiologic studies have demonstrated that senior age at menarche and junior age at menopause are associated with an increased incidence of cataract, and that endogenous estrogen or postmenopausal hormone replacement therapy (HRT) may prevent cataract development. The molecular mechanisms behind this phenomenon are largely undetermined. Estrogen confers protection against cataract through antioxidative impairment, maintains normal function of lenticular membrane, TGF-beta mediated and estrogen receptor mediated effects. The research of these effects and its interactions may lead to a better understanding of the protective mechanism of estrogen and also provide a new thought for treatment and prevention of cataract.

Animals↗
PubMed2005

Hepatitis B revaccination in healthy non-responder Chinese children: five-year follow-up of immune response and immunologic memory.

To assess persistence of anti-HBs and immunologic memory of non-responders after revaccination, 40 healthy non-responder children were given a three-dose recombinant hepatitis B vaccine revaccination randomly by intramuscular (10 microg per dose) or intradermal (2 microg per dose) route and followed up to five years. All 17 intramuscular and 22 of 23 intradermal children developed a seroprotective antibody response (anti-HBs>or=10 mIU/mL) after revaccination. Children of intramuscular group had significantly higher seroprotection rates and anti-HBs geometric mean titers than the intradermal group. At year 5, 50% of children in intramuscular group, but only 18.2% of intradermal group still maintained seroprotection (P=0.075). By the end of follow-up, a booster dose (5 microg) was given to those who had lost seroprotection. All the eight intramuscular children developed an anamnestic response with increase of anti-HBs level by 215 times, but two of the 18 intradermal children failed to produce seroprotective level. Three-routine-dose intramuscular revaccination was significantly more effective than low-dose intradermal revaccination with the same number of injections. No child seroconverted to HBsAg, and 11 had transient infections indicated by seroconversion to anti-HBc. These results demonstrated that non-responders could benefit from three doses intramuscular revaccination not only in high proportion of anti-HBs conversion but also in long-term persistence of seroprotection, and more importantly in preservation of the immunologic memory years after loss of protective anti-HBs.

Adolescent↗
PubMed2005

Analysis of the Xenopus Werner syndrome protein in DNA double-strand break repair.

Werner syndrome is associated with premature aging and increased risk of cancer. Werner syndrome protein (WRN) is a RecQ-type DNA helicase, which seems to participate in DNA replication, double-strand break (DSB) repair, and telomere maintenance; however, its exact function remains elusive. Using Xenopus egg extracts as the model system, we found that Xenopus WRN (xWRN) is recruited to discrete foci upon induction of DSBs. Depletion of xWRN has no significant effect on nonhomologous end-joining of DSB ends, but it causes a significant reduction in the homology-dependent single-strand annealing DSB repair pathway. These results provide the first direct biochemical evidence that links WRN to a specific DSB repair pathway. The assay for single-strand annealing that was developed in this study also provides a powerful biochemical system for mechanistic analysis of homology-dependent DSB repair.

Animals↗
PubMed2005

The properties of CpG islands in the putative promoter regions of human immunoglobulin (Ig) genes.

CpG island is a GC-rich motif occurred in gene promoter region, which can play important roles in gene silencing and imprinting. Here, we present a set of discriminant functions that can recognize the structural and compositional features of CpG islands in the putative promoter regions (PPRs) of human and mouse immunoglobulin (Ig) genes. We showed that the PPRs of both human and mouse Ig genes irrespective of gene chromosomal localization are apparently CpG island poor, with a low percentage of the CpG islands overlapped with the transcription start site (TSS). The human Ig genes that have CpG islands in the PPRs show a very narrow range of CpG densities. 47% of the Ig genes fall in the range of 3.5-4 CpGs/100 bp. In contrast, the non-Ig genes examined have a wide range of the density of CpG island, with 10.5% having the density of 8.1-15 CpGs/100 bp. Meantime, five patterns of the CpG distributions within the CpG islands have been classified: Pat A, B, C, D, and E. 21.6% and 10.8% of the Ig genes fall into the Pat B and Pat D groups, respectively, which were significantly higher than the non-Ig genes examined (8.2% and 3.8%). Moreover, the length of CpG islands is shorter in human Ig genes than in non-Ig genes but is much longer than in mouse orthologues. These findings provide a clear picture of non-neutral and nonrandom occurrence of the CpG islands in the PPRs of human and mouse Ig genes, which facilitate rational recommendations regarding their nomenclature.

Animals↗
PubMed2005

CYP2E1-dependent hepatotoxicity and oxidative damage after ethanol administration in human primary hepatocytes.

AIM: To observe the relationship between ethanol-induced oxidative damage in human primary cultured hepatocytes and cytochrome P450 2E1 (CYP2E1) activity, in order to address if inhibition of CYP2E1 could attenuate ethanol-induced cellular damage. METHODS: The dose-dependent (25-100 mmol/L) and time-dependent (0-24 h) exposures of primary human cultured hepatocytes to ethanol were carried out. CYP2E1 activity and protein expression were detected by spectrophotometer and Western blot analysis respectively. Hepatotoxicity was investigated by determination of lactate dehydrogenase (LDH) and aspartate transaminase (AST) level in hepatocyte culture supernatants, as well as the intracellular formation of malondialdehyde (MDA). RESULTS: A dose-and time-dependent response between ethanol exposure and CYP2E1 activity in human hepatocytes was demonstrated. Moreover, there was a time-dependent increase of CYP2E1 protein after 100 mmol/L ethanol exposure. Meanwhile, ethanol exposure of hepatocytes caused a time-dependent increase of cellular MDA level, LDH, and AST activities in supernatants. Furthermore, the inhibitor of CYP2E1, diallyl sulfide (DAS) could partly attenuate the increases of MDA, LDH, and AST in human hepatocytes. CONCLUSION: A positive relationship between ethanol-induced oxidative damage in human primary cultured hepatocytes and CYP2E1 activity was exhibited, and the inhibition of CYP2E1 could partly attenuate ethanol-induced oxidative damage.

Cells, Cultured↗
PubMed2005

Cooperative metal-boron interactions in the reaction of nido-1,2-(Cp*RuH)2B3H7, Cp* = eta5-C5Me5, with HC(triple bond)CPh.

Products of the reaction of nido-1,2-(CpRuH)(2)B(3)H(7), 1, and phenylacetylene demonstrate the ways in which cluster metal and main group fragments can combine with an alkyne. Observed at 22 degrees C are (a) reduction to mu-alkylidene Ru-B bridges (isomers nido-1,2-(CpRu)(2)(1,5-mu-C{Ph}Me)B(3)H(7), 2, and nido-1,2-(CpRu)(2)(1,5-mu-C{CH(2)Ph}H)B(3)H(7), 3), (b) reduction to exo-cluster alkyl substituents on boron (nido-1,2-(CpRuH)(2)-3-CH(2)CH(2)Ph-B(3)H(6), 4), (c) cluster insertion with extrusion of a BH(2) fragment into an exo-cluster bridge (nido-1,2-(CpRu)(2)(mu-H)(mu-BH(2))-4-or-5-Ph-4,5-C(2)B(2)H(5), 5), (d) combined insertion with BH(2) extrusion and reduction (nido-1,2-(CpRu)(2)(mu-H)(mu-BH(2))-3-CH(2)CH(2)Ph-5-Ph-4,5-C(2)B(2)H(4), 6), (e) insertion and loss of borane with and without reduction (nido-1,2-(CpRu)(2)-5-Ph-4,5-C(2)B(2)H(7), 7, and isomers nido-1,2-(CpRu)(2)-3-CH(2)CH(2)Ph-4-(and-5-)Ph-C(2)B(2)H(6), 8 and 9), and (f) insertion and borane loss plus reduction (nido-1,2-(CpRu)(2)-3-(trans-CH=CHPh)-5-Ph-4,5-C(2)B(2)H(6), 10). Along with 7, 8, and 10, the reaction at 90 degrees C generates products of insertion and nido- to closo-cluster closure (closo-4-Ph-1,2-(CpRuH)(2)-4,6-C(2)B(2)H(3), 11, closo-1,2-(CpRuH)(2)-3-CH(2)CH(2)Ph-5-Ph-7-CH(2)CH(2)Ph-4,5-C(2)B(3)H(2), 12, closo-1,2-(CpRuH)(2)-5-Ph-4,5-C(2)B(3)H(4), 13, and isomers closo-1,2-(CpRuH)(2)-3-and-7-CH(2)CH(2)Ph-5-Ph-4,5-C(2)B(3)H(3), 14 and 15). The clusters with an exo-cluster bridging BH(2) groups are shown to be intermediates by demonstrating that the major products 5 and 6 rearrange to 13 and convert to 14, respectively. 14 then isomerizes to 15, thus connecting low- and high-temperature products. Finally, all available information shows that the high reactivity of 1 with alkynes can be associated with the "extra" two Ru-H hydrides on the framework of 1 which are required to meet the nido-cluster electron count.

Journal Article↗
PubMed2005

Clinical and protein metabolic efficacy of glutamine granules-supplemented enteral nutrition in severely burned patients.

As an abundant amino acid in the human body, glutamine has many important metabolic roles that may protect or promote tissue integrity and enhance the immune system. A relative deficiency of glutamine in such patients could compromise recovery and result in prolonged illness and an increase in late mortality. The purpose of this clinical study is to observe the effects of enteral supplement with glutamine granules on protein metabolism in severely burned patients. Forty-eight severe burn patients (total burn surface area 30-75%, full thickness burn area 20-58%) who met the requirements of the protocol joined this double-blind randomized controlled clinical trial. Patients were randomly divided into two groups: burn control group (B group, 23 patients) and glutamine treated group (Gln group, 25 patients). There was isonitrogenous and isocaloric intake in both groups, glutamine and B group patents were supplemented with glutamine granules or placebo (glycine) at 0.5 g/kg per day for 14 days with oral feeding or tube feeding, respectively. The level of plasma glutamine, plasma protein content, urine nitrogen and urine 3-methylhistidine (3-MTH) excretion were determined, wound healing rate of the burned area and hospital stay were recorded. The results showed that there were significant reductions in plasma glutamine level and abnormal protein metabolism. After supplement with glutamine granules for 14 days, the plasma glutamine concentration was significantly higher than that in B group (607.86+/-147.25 micromol/L versus 447.63+/-132.38 micromol/L, P<0.01) and the plasma prealbumin and transferrin in Gln group were remarkably higher than those in B group (P<0.01), but the concentration of total protein and albumin were not significantly changed compared with B group (P>0.05). On the other hand, the amount of urine nitrogen and 3-MTH excreted in Gln group were significantly lower than that in B group. In addition, wound healing was faster and hospital stay days were shorter in Gln group than B group (46.59+/-12.98 days versus 55.68+/-17.36 days, P<0.05). These indicated that supplement glutamine granules with oral feeding or tube feeding could abate the degree of glutamine depletion, promote protein synthesis, inhibit protein decompose, improve wound healing and reduce hospital stay.

Adolescent↗
PubMed2005

Genistein inhibited retinal neovascularization and expression of vascular endothelial growth factor and hypoxia inducible factor 1alpha in a mouse model of oxygen-induced retinopathy.

The effects of genistein on neovascularization, vascular endothelial growth factor (VEGF), and hypoxia inducible factor 1alpha (HIF1alpha) protein expression in a mouse model of oxygen-induced retinopathy were studied. The model of oxygen-induced retinal neovascularization was induced in newborn C57BL/6 mice by exposing 7-day-old mice to 75% oxygen for 5 days and then housing them in room air (relative hypoxia). Retinopathy was assessed by quantitation of vascular cell nuclei anterior to inner limiting membrane. Judged by relative fluorescence using a confocal scanning laser microscope coupled to a computer, VEGF and HIF1alpha protein expression were investigated. Genistein markedly inhibited the numbers of nuclei protruding above the inner limiting membrane under relative hypoxia conditions. The levels of nuclei numbers were suppressed by 50, 100, and 200 mg/kg body weight /day genistein to 87.4%, 72.0%, and 59.4%, respectively, compared to that untreated with genistein. VEGF protein was constitutively expressed in the preretinal area under normoxia conditions. Genistein markedly inhibited relative-hypoxia-elicited VEGF expression elevation in a dose-dependent manner. HIF1alpha expression was also observed in normoxia conditions. There was a 2.4-fold induction in preretinal HIF1alpha expression in oxygen-reared animals when compared to room-air-reared animals. Genistein dose-dependently suppressed HIF1alpha protein expression. These results indicated that the inhibition of VEGF and HIF1alpha protein expression by genistein may partly account for its effect on retinal neovascularization in vivo, and genistein could be an effective agent in the prevention and treatment of ocular neovascularization.

Angiogenesis Inhibitors↗
PubMed2005

Effects of melatonin in age-related macular degeneration.

Age-related macular degeneration (AMD) is the leading cause of severe visual loss in aged people. Melatonin has been shown to have the capacity to control eye pigmentation and thereby regulate the amount of light reaching the photoreceptors, to scavenge hydroxyradicals and to protect retinal pigment epithelium (RPE) cells from oxidative damage. Therefore, it is reasonable to think that the physiological decrease of melatonin in aged people may be an important factor in RPE dysfunction, which is a well known cause for initiation of AMD. Our purpose is to explore a new approach to prevent or treat AMD. We began case control study with a follow-up of 6 to 24 months. One hundred patients with AMD were diagnosed and 3 mg melatonin was given orally each night at bedtime for at least 3 months. Both dry and wet forms of AMD were included. Fifty-five patients were followed for more than 6 months. At 6 months of treatment, the visual acuity had been kept stable in general. Though the follow up time is not long, this result is already better than the otherwise estimated natural course.1,2 The change of the fundus picture was remarkable. Only 8 eyes showed more retinal bleeding and 6 eyes more retinal exudates. The majority had reduced pathologic macular changes. We conclude that the daily use of 3 mg melatonin seems to protect the retina and to delay macular degeneration. No significant side effects were observed.

Aged↗
PubMed2005

[Detection of interaction of binding affinity of aromatic hydrocarbon receptor to the specific DNA by exonuclease protection polymerase chain reaction assay].

OBJECTIVE: To establish an exonuclease protection mediated polymerase chain reaction (PCR) assay for the non-radioactive, sensitive detection of the binding of protein and DNA. METHODS: The 1 pmol/L-10 nmol/L 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) dissolved in dimethyl sulphoxide (DMSO), was added into 100 microl SD rat hepatic cytosol in vitro, which contained different amount of aromatic hydrocarbon receptors (AhR) and relative proteins, and ligand-AhR-DRE complex were formed in addition to 1 fmol/L-100 nmol/L DNAs probes containing the sequence of DRE. With the digestion of Exonuclease III and S1 nuclease, free DNAs were digested to oligonucleotide and binding DNA remained due to protein (AhR) protection and be amplified by PCR. The results of PCRs were shown by loading on 2% agarose electrophoresis. DMSO was used as negative control and blank control was set up. RESULTS: Target DNA (285 bp) could be observed in the ligand groups, but not in the control group. The minimal amount of receptor was 2.5 fmol/L and the minimal amount of DNA probes was 2 fmol. CONCLUSIONS: Exonuclease protection mediated PCR assay should be a good non-radioactive tool to quantify the interaction of protein and DNA with high sensitivity and simplicity.

Animals↗
PubMed2005

[Application of fractal dimension in heart rate variability analysis during head-down tilt].

OBJECTIVE: The paper applies the fractal dimension to heart rate variability (HRV), and discusses the changes of the fractal dimension of cardiovascular system during head down tilt (HDT). METHOD: ECG of 10 subjects were recorded during HDT, the experiment was repeated in each subject. Fractal dimension was used to analyze the HRV. RESULT: Compared to supine before HDT, the standard deviation of all normal to normal RR intervals (SDNN) at 15-20 min, 20-25 min, 25-30 min and restoration increased significantly; the root mean square of successive differences between adjacent normal cycles (rMSSD) at 20-25 min increased significantly; the fractal dimension at 0-5 min, 5-10 min, 10-15 min, 20-25 min, 25-30 min and restoration increased significantly. CONCLUSION: The result shows that HRV and the nonlinearity of cardiovascular system increase during HDT. It is feasible that the fractal dimension can be used for analyzing HRV.

Cardiovascular Physiological Phenomena↗
PubMed2005

Acupuncture for treatment of climacteric syndrome--a report of 35 cases.

OBJECTIVE: To evaluate the effects of acupuncture for treatment of climacteric syndrome. METHODS: The 65 cases in this series were randomly assigned to the acupuncture group (N=35) and the control group (N=30), with the former treated by acupuncture and the latter by medication respectively. The therapeutic effects were evaluated by means of the clinical outcome, improvement in the symptom scores and the results of radioimmunoassays. RESULTS: In the acupuncture group, 12 cases were cured, 16 cases markedly effective, and 6 cases improved, the total effective rate being as high as 97.14%. The decrease in the symptom scores, and especially the elevation of the decreased E2 level and the decrease of the increased FSH and LH levels, demonstrated that acupuncture therapy was superior to medication. CONCLUSION: Acupuncture for regulating the mental activities and reinforcing the kidney is an effective therapy for climacteric syndrome.

Acupuncture Therapy↗
PubMed2005

Comparative study on effects of burn-blast combined injury and burn-firearm combined injury complicated with seawater immersion on vascular endothelial cells.

OBJECTIVE: To comparatively study the effects and mechanisms of burn-blast combined injury and burn-firearm combined injury complicated with seawater immersion on vascular endothelial cells. METHODS: A total of 40 healthy adult hybrid dogs of both sexes, weighing 12-15 kg, were used in this study. Randomly-selected 20 dogs were established as models of burn-blast combined injury (the burn-blast injury group) and the other 20 dogs as models of burn-firearm combined injury (the burn-firearm injury group). Then the wounds of all the dogs were immediately immersed in seawater for 4 hours, and then they were taken out from the seawater. Blood samples were withdrawn from the central vein of the dogs before injury, and at 4, 7, 10, 20, and 28 hours after injury to measure the circulating endothelial cells and the von Willebrand factor. RESULTS: Circulating endothelial cells increased significantly at 4 hours after injury in all the dogs. But they reached peak at 7 hours after injury in the burn-blast injury group and at 28 hours after injury in the burn-firearm injury group. The changes of circulating endothelial cells in the burn-blast injury group were significantly different from those in the burn-firearm injury group at 4, 7, 20, and 28 hours after injury (P < 0.01). The von Willebrand factor reached peak at 4 hours after injury in the burn-blast injury group and at 28 hours in the burn-firearm injury group. The changes of von Willebrand factor in the burn-blast injury group were significantly different from those in the burn-firearm injury group at 4, 20, and 28 hours after injury (P < 0.01). CONCLUSIONS: In burn-blast injury combined with seawater immersion, the vascular endothelial cells changed most significantly at 4 hours or 7 hours after injury, while burn-firearm injury combined with seawater immersion have the same at 20 hours or 28 hours after injury.

Animals↗