PubMed Health⌕ Search

Biomedical subjects

Bo Chen

Publications and source records attributed to Bo Chen.

At least 55 records · Page 3Linked to original sources
PubMed2006

[Preliminary clinical study of microimplants in the restoration of edentulous jaws].

OBJECTIVE: To investigate if magnetic- attached overdenture supported by microimplants of 2.5 mm in diameter was able to function properly. METHODS: Fourteen microimplants were placed in 4 patients. Implants were exposed 3 months later and magnetic abutments were connected directly. X-ray was taken during the 3 year follow-up to examine marginal bone level. Peri-implant soft tissue was also checked. Denture retention, chewing stability and overall satisfaction with the microimplants retained overdenture were evaluated. RESULTS: All of the 14 microimplants achieved initial primary stability without infection or any other postoperative complications. No implant was lost during the follow-up period. Only one magnetic abutment fractured one year after restoration and was replaced. X-ray showed highly stable marginal bone level around the microimplants. The patients were satisfied with the restoration. CONCLUSIONS: The microimplants retained overdenture leads to a significant improvement of function despite of the small dimensions of these implants. In particular for elder patients with severe residual ridge resorption, this treatment represents a less invasive alternative compared to conventional implant systems.

Aged↗
PubMed2006

[Clinical study of periocline on peri-implantitis treatment].

OBJECTIVE: To evaluate the clinical outcome and the effects of treating peri-implantitis with periocline. METHODS: Thirty-two sites in 32 implants with peri-implantitis were treated with periocline. The parameters including plaque index, probing depth (PD) of pocket, sulcular bleeding index (SBI) were measured at baseline, 1, 3, 6 and 12 weeks after treatment and followed up for 6 months. RESULTS: Statistically significant decrease (P < 0.05) in SBI, and PD occurred at all time intervals compared to baseline. The treatment could last for at lest four weeks in peri-implantitis cases without fistula. CONCLUSIONS: Periocline could be safely and effectively used in treating peri-implantitis in cases without peri-implant fistula. Peri-implantitis with fistula should be treated in combination with surgical methods, and periocline can also be used to control inflammation before surgery.

Adult↗
PubMed2006

[Changes of serum and cerebrospinal fluid insulin-like growth factor-II levels in neonates with hypoxic-ischemic encephalopathy].

OBJECTIVE: Many studies have demonstrated that low levels of insulin-like growth factor-I (IGF-I) may be associated with the hypoxic-ischemic brain damage (HIBD) and that IGF-I has a neuroprotective effect. The role of IGF-II, a structurally and functionally homologous polypeptide with IGF-I, is unclear in HIBD. This study was designed to observe the changes of serum and cerebrospinal fluid (CSF) IGF-II levels in neonates with hypoxic-ischemic encephalopathy (HIE) and to investigate its effects on HIE. METHODS: Serum and CSF IGF-II levels in 41 neonates with HIE were measured by radioimmunoassay in the acute phase (postnatal age 12-24 hrs) and the convalescence phase (postnatal age 10-12 days). The 41 HIE neonates included 10 cases of mild, 12 moderate, and 19 severe HIE. Serum samples of 10 normal neonates were used as controls. RESULTS: In the acute phase, serum IGF-II levels in the Mild HIE group (203.28 +/- 40.09 ng/mL) and the Moderate HIE group (192.33 +/- 39.66 ng/mL) were not significantly reduced, but were obviously reduced in the Severe HIE group (116.72 +/- 39.50 ng/mL) compared with normal controls (229.38 +/- 43.39 ng/mL) (P<0.01). During the convalescence phase, serum IGF-II levels in the Mild HIE group (285.53 +/- 49.44 ng/mL) and in the Moderate HIE group (278.69 +/- 51.34 ng/mL) increased significantly (P < 0.01); CSF IGF-II levels increased in the Mild HIE group from 27.23 +/- 7.82 ng/mL (acute phase) to 81.58 +/- 9.77 ng/mL (convalescence phase) (P < 0.01) and also increased in the Moderate HIE group from 23.43 +/- 7.79 ng/mL (acute phase) to 78.48 +/- 10.44 ng/mL (convalescence phase) (P < 0.01). The patients from the severe HIE group whose neurological symptoms or signs were improved in the convalescence showed higher serum and CSF IGF-II levels than in the acute phase (254.08 +/- 48.50 ng/mL vs 122.21 +/- 46.26 ng/mL; 69.42 +/- 10.20 ng/mL vs 15.05 +/- 7.03 ng/mL; P < 0.01). A positive correlation was found between the serum and CSF IGF-II levels in the HIE group (r=0.69, P < 0.01). CONCLUSIONS: IGF-II levels in serum and CSF are associated with the pathogenesis and the prognosis of neonatal HIE.

Female↗
PubMed2006

[Activity of esterases and effect of genetic polymorphism in workers exposed to organophosphorus pesticides].

OBJECTIVE: To study the activity of esterases, including butyrylcholinesterase (BchE), carboxylesterase (CarbE), paraoxonase (PonE) and acetylcholinesterase (AChE), and to explore the effect of genetic polymorphism on the activity of esterase for workers exposed to organophosphorus pesticides (OPs). METHODS: Two hundred and forty-one long term OPs directly exposed workers and 151 indirectly exposed workers in the same factory were taken as study group. One hundred and sixty unexposed persons were taken as control group. The activity of serum enzymes was measured and the polymorphic distribution was detected using 7900 genotype detecting system and CMOS Chip technique. The effect of long-term exposure to organophosphorus pesticides was analyzed. RESULTS: The activities of BchE, CarbE and PonE were independent on the gender or age in control group. Average values of Carb and BchE activities of directly and indirectly exposed workers were lower than those in control group respectively. PonE activity in directly exposed group was lower than that in control group. AChE activity in directly exposed group was lower than that in indirectly exposed group. All the differences were significant (P < 0.01). In the direct exposure group, the frequency of three variants of butyrylcholinesterase gene K (BCHE-K) polymorphism was 74.3%, 24.1% and 1.6% for UU, UK and KK respectively. Frequency of allele U and K was 0.863 and 0.137 respectively in the same group. Frequency of three variants of PON192 polymorphism was 15.0%, 45.5% and 39.5% for AA, AB and BB respectively in direct exposure group. Gene frequency of low activity (PON*A) and high activity (PON*B) was 0.378 and 0.622 respectively. Frequency of three variants of PON55 polymorphism was 96.2%, 3.8% and 0% for MM, LM and LL respectively in direct exposure group. Frequency of allele M and L was 0.981 and 0.019 respectively in the same group. The activity of PON was different in various genotypes of PON192 and PON55. CONCLUSION: The long-term exposure to OPs could inhibit the activities of CarbE, BchE, PonE and ACh E in different level. The genetic polymorphisms of PON192 and PON55 affect the activity of PonE, which is related to the detoxification of OPs and health impact.

Acetylcholinesterase↗
PubMed2006

[Effects of metolachlor on biological activities in celery rhizophere and non-rhizosphere soil].

The study with rhizobag showed that in celery rhizophere and non-rhizosphere soil, metolachlor had a certain inhibitory effect on catalase activity, but stimulated dehydrogenase activity. Generally, the enzyme activities in rhizosphere soil were higher than those in non-rhizosphere soil. After 45 days of metolachlor treatment, the numbers of bacteria and fungi in rhizosphere soil were higher than those in non-rhizosphere soil, and the R/S was 1.76 to approximately 2. 51. The numbers of actinomycetes were relatively stable, and the rhizosphere effect was not significant. The degradation rate of metolachlor in rhizosphere and nonrhizosphere soil was 0. 0217 and 0.0176, and the corresponding half-live was 31.9 and 39.4 days, respectively. The degradation of metolachlor was enhanced greatly in rhizosphere soil.

Acetamides↗
PubMed2006

[Clinical application of PET and PET/CT in radiotherapy of head and neck cancer].

Positron emission tomography (PET) is a functional imaging modality. The combined PET and CT scan provides more accurate detection of tumors and their relationship with normal tissues by providing the functional and anatomic information simultaneously. Relevant researches have been focused on the application of combined PET/CT in the radiotherapy of head and neck cancer, which includes: providing valuable information in the staging of head and neck cancer before radiotherapy; localizing a primary tumor in patients with unknown metastases in cervical lymph nodes; predicting the response of tumors to radiotherapy; providing biological target volume to radiation treatment planning, especially in intensity-modulated radiotherapy; and monitoring the residual and recurrent diseases after radiotherapy. However, its application in many aspects is still controversy, and further researches in its clinical application are still needed.

Head and Neck Neoplasms↗
PubMed2006

[Elevation of some serum liver enzymes in coke oven workers and the possible relationship with exposure to polycyclic aromatic hydrocarbons].

OBJECTIVE: To explore the dose-response relationship between exposure to polycyclic aromatic hydrocarbons (PAHs) and the elevation of some serum liver enzymes in coke oven workers. METHODS: Cumulative exposure level of total 16 PAHs (CEL-PAHs) and urinary 1-hydroxypyrene (1-OHP) concentrations were assessed, liver enzymes including alanine aminotransferase (ALT), aspartate aminotransferase (AST), gamma-glutamyl transpeptidase (GGT) and alkaline phosphatase (ALP) were determined between coke oven workers and non-occupational PAHs exposed workers with negative hepatitis B surface antigens (HBsAg). RESULTS: The exposure levels of PAHs in coke oven workers were significantly higher than in control group (P < 0.05). Compared with referents, significant elevation of serum ALT can be found in the group of CEL-PAHs minor than 50 microg/(m3 x a) or in the group of urinary 1-OHP concentrations minor than 2.3 micromol/mol creatinine, as well as significant elevation of serum AST in the group of CEL-PAHs minor than 50 microg/(m3 x a) (P < 0.05). Compared with control group, the elevation of enzyme level in all four serum liver and the higher prevalence of abnormal serum ALT, AST and GGT level can be found both in the group of CEL-PAHs higher than 200 microg/(m3 x a) and in the group of urinary 1-OHP concentrations higher than 10.0 micromol/mol creatinine (P < 0.05), especially for the elevation of enzyme level in serum GGT (10-fold increase in CEL-PAHs resulted in 1.24-fold increase in serum GGT, as well as 10-fold increase in urinary 1-OHP resulted in 1.19-fold increase) and higher prevalence in serum GGT (logistic analysis: adjusted Odds Ratio: 6.2 - 7.2, P < 0.05). CONCLUSION: The elevation of some liver enzymes in coke oven workers may be related to their high exposure level of PAHs.

Air Pollutants, Occupational↗
PubMed2006

[Determination of orlistat in health food for controlling body weight by high performance liquid chromatography/electrospray spectrometry].

OBJECTIVE: To establish a method of determining orlistat in health food by on line HPLC-UV-ESI/MS. METHODS: The separation was completed on an analytical Spherigel C8 column (5 microm, 200 mm x 4.6 mm) with acetonitrile (0.1% formic acid) : water (0.1% formic acid) = 80 : 20 as mobile phase, the detection wavelength was 2003 mm. RESULTS: Good linearity between peak areas and concentrations was obtained during rag of 0.3 - 0.6 mg/ml. CONCLUSION: The method is simple and can be used to determine orlistat in the health food for controlling body weight accurately.

Anti-Obesity Agents↗
PubMed2006

[In vitro effect of daphnetin on cytochrome C oxidase and ribonucleotide reductase of plasmodium falciparum].

OBJECTIVE: To test the in vitro effect of daphnetin on cytochrome C oxidase (COX) and ribonucleotide reductase (RNR) activity of Plasmodium falciparum. METHODS: P. falciparum (FCC1/HN) was cultured in vitro using the method of Trager and Jensen. The effect of daphnetin and daphnetin-Fe complex on COX and RNR activity of P. falciparum was tested by ultraviolet spectrophotometer and electron spin resonance (ESR) respectively. RESULT: The parasites synchronized with sorbitol in vitro was treated by daphnetin and daphnetin-Fe complex. The inhibition level of the COX activity by daphnetin after being treated for 2, 4, 8 and 12 h were 0.6%, 73% and 80% respectively and the inhibition level by daphnetin at different concentrations (0.1, 1, 100 and 1 mmol/L) for 6h was 3%, 31%, 53% and 84%, respectively. No considerable effect was observed on the COX activity of P. falciparum treated with daphnetin-Fe complex. The tyrosyl free radical was tested to reflect the RNR activity of P. falciparum at various times by ESR. The inhibition level by daphnetin for 1, 2, 3 and 4 h were 7%, 51%, 69% and 75% respectively, while the values treated by daphnetin-Fe complex were 8%, 6%, 11% and 9% respectively. The inhibition level by daphnetin at different concentrations (0.1, 1, 100 and 1 mmol/L) for 6 h was 3%, 31%, 58% and 93% respectively and while the values treated by daphnetin-Fe complex were 8%, 6%, 11% and 9%. CONCLUSION: Daphnetin significantly reduces the COX and RNR activities of Plasmodium falciparum in vitro.

Animals↗
PubMed2006

Assessing the willingness of the public to pay to conserve urban green space: the Hangzhou City, China, case.

The authors assessed the willingness of residents to pay for urban green-space conservation in Hangzhou, China, using the contingent-valuation method. The aim of the study was to provide policy makers with information that would be useful for making informed decisions in urban-development planning. The findings of the study are as follows: 1) The willingness of residents to pay for urban green-space conservation was positively correlated with their perceptions of the benefits of green spaces and negatively correlated with perceptions of the annoyances. 2) The willingness to pay a higher premium for green-space conservation is directly related to gender, income level, and residential-ownership status. Age and education level are not significantly correlated with willingness to pay. 3) A majority of respondents view the conservation of urban green spaces as a very important function of the city, and most of them are willing to pay additional taxes for this conservation. 4) The total value per year to the public of the conservation program in Hangzhou is about $15.4 million. These qualitative and quantitative findings can be used in the policy-making process for urban-development plans.

China↗
PubMed2005

Dicationic pyridium porphyrins appending different peripheral substituents: synthesis and studies for their interactions with DNA.

Twelve trans-dicationic pyridium porphyrins appending different peripheral substituents were synthesized and their abilities to bind and cleave DNA under irradiation have been investigated. Their binding modes to DNA were studied by UV-vis spectroscopy, circular dichroism. The apparent constants were measured by EB competitive fluorescence method and most of them were in the range of 10(4)-10(5) M(-1). We found that both the position of positive charges and steric hindrance could greatly influence their binding affinities and modes to DNA, and then affect their photocleaving abilities to DNA.

Cations↗
PubMed2005

Simultaneous determination of water-soluble and fat-soluble synthetic colorants in foodstuff by high-performance liquid chromatography-diode array detection-electrospray mass spectrometry.

An accurate method was developed for the simultaneous determination of water-Tartrazine, Amaranth, Ponceau 4R, Sunset Yellow FCF, and fat-Sudan (I-IV), synthetic soluble colorants in foodstuff. This method uses dimethylsulfoxide (DMSO) as the extraction solvent in the sample preparation process and high performance liquid chromatography (HPLC)-diode array detector (DAD)-electrospray mass spectrometry (ESI-MS), applying selected ion recording in positive/negative alternate mode to acquire mass spectral data, as the analytical technique. Linearity of around three orders in the magnitude of concentration was generally obtained. Detection and quantification limits of the investigated dyes, which were evaluated at signal to noise ratio of 3 for detection limit and 10 for quantification limit, were in the ranges of 0.01-4 and 0.03-11.2 ng, respectively. The recoveries of the eight synthetic colorants in four matrices ranged from 93.2 to 108.3%. Relative standard deviations of less than 8.2% were also achieved. This method has been applied successfully in the determination of water-soluble colorants in the soft drink and the delicious ginger, and fat-soluble dyes in chilli powders and chilli spices.

Beverages↗
PubMed2005

Metal-free silicon-molecule-nanotube testbed and memory device.

Work from several laboratories has shown that metal nanofilaments cause problems in some molecular electronics testbeds. A new testbed for exploring the electrical properties of single molecules has been developed to eliminate the possibility of metal nanofilament formation and to ensure that molecular effects are measured. This metal-free system uses single-crystal silicon and single-walled carbon nanotubes as electrodes for the molecular monolayer. A direct Si-arylcarbon grafting method is used. Use of this structure with pi-conjugated organic molecules resulted in a hysteresis loop with current-voltage measurements that are useful for an electronic memory device. The memory is non-volatile for more than 3 days, non-destructive for more than 1,000 reading operations and capable of more than 1,000 write-erase cycles before device breakdown. Devices without pi-conjugated molecules (Si-H surface only) or with long-chain alkyl-bearing molecules produced no hysteresis, indicating that the observed memory effect is molecularly relevant.

Computer Storage Devices↗
PubMed2005

SARS coronavirus 7a protein blocks cell cycle progression at G0/G1 phase via the cyclin D3/pRb pathway.

The genome of severe acute respiratory syndrome-associated coronavirus (SARS-CoV) contains four structural genes that are homologous to genes found in other coronaviruses, and also contains six subgroup-specific open reading frames (ORFs). Expression of one of these subgroup-specific genes, ORF7a, resulted in apoptosis via a caspase-dependent pathway. Here, we observed that transient expression of ORF7a protein fused with myc or GFP tags at its N or C terminus inhibited cell growth and prevented BrdU incorporation in different cultural cells, suggesting that ORF7a expression may regulate cell cycle progression. Analysis by flow cytometry demonstrated that ORF7a expression was associated with blockage of cell cycle progression at G0/G1 phase in HEK 293 cells after 24 to 60 h post-transfection. Similar results were observed in COS-7 and Vero cells. Mutation analysis of ORF7a revealed that the domain spanning aa 44-82 of 7a protein was essential for its cytoplasmic localization and for induction of the cell cycle arrest. After analyzing the cellular proteins involving in regulation of cell cycle progression, we demonstrated that ORF7a expression was correlated with a significant reduction of cyclin D3 level of mRNA transcription and expression, and phosphorylation of retinoblastoma (Rb) protein at ser795 and ser809/811, not with the expression of cyclin D1, D2, cdk4 and cdk6 in HEK 293 cells. These results suggest that the insufficient expression of cyclin D3 may cause a decreased activity of cyclin D/cdk4/6, resulting in the inhibition of Rb phosphorylation. Accumulation of hypo- or non-phosphorylated pRb thus prevents cell cycle progression at G0/G1 phase.

Animals↗
PubMed2005

A novel open-framework copper borophosphate: Cu(H2O)2[B2P2O8(OH)2].

A new open-framework copper borophosphate was hydrothermally synthesized and structurally characterized. Its structure may be regarded as a layer forming via vertex-sharing BO3(OH) and PO4 tetrahedra bonded together with CuO2(OH)2(H2O)2 octahedral units. The thermal stability and magnetic properties are also discussed.

Journal Article↗