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Biomedical subjects

Y F Shen

Publications and source records attributed to Y F Shen.

At least 19 recordsLinked to original sources
PubMed2005

Repellent and insecticidal activities of essential oils from Artemisia princeps and Cinnamomum camphora and their effect on seed germination of wheat and broad bean.

Repellent and insecticidal activities of essential oils extracted from leaves of Artemisia princeps Pamp and seeds of Cinnamomum camphora (L.) Presl. against storage pests Sitophillus oryzae L. and Bruchus rugimanus Bohem were investigated. Results showed that the two individual oils displayed good, but their mixture (1:1) exhibited much better repellent activities at concentrations from 250 to 1000 microg g(-1) and insecticidal actions at concentrations 1000 microg g(-1) against the test beetles S. oryzae and B. rugimanus. Oils from A. princeps and C. camphora applied individually were significantly toxic to seed germination of wheat at 500 microg ml(-1). However, no toxic effects were found when the two oils were mixed (1:1 w/w) at the same concentration. These observations indicated that the mixture of the two plant-derived oils had a synergic effect and could be used in the control of storage pests.

Animals↗
PubMed2001

Double-coping technique in prosthesis fabrication for osseointegrated teeth implantation: case report.

Reconstruction of segmental mandibular defects resulting from trauma, infection, or tumor resection still remains difficult. Although cosmetic improvement was seen in patients who had immediate reconstruction of the mandibular continuity, normal mastication and deglutition could not be achieved by conventional removable dentures. Since 1988, the treatment protocol has been modified to use endosseous root-form implants to support dental prostheses instead of the conventional removable prostheses in these patients. There are 2 types of prostheses that can be constructed over dental implants: (1) a removable implant overdenture and (2) a fixed detachable prosthesis. Although the latter better meets in patients' psychological needs, it may present problems such as phonetic discrepancies, food impaction, difficult home care, and poor esthetics if the patient has a high lip line. In addition, it is not easy to fabricate accurately in the laboratory. To overcome these problems, a case is presented to illustrate the use of another fixed-type prosthesis, a double-coping technique, for fabricating dentures so that any discrepancy between the inner and outer copings can be filled by cement. The technique not only improves the shortcomings of fixed detachable prostheses but also satisfactorily meets patients' desire for normal mastication and deglutition. Follow-up after 4 years showed no significant changes around the implants by clinical and radiographic examinations.

Dental Implantation↗
PubMed2001

[Role of STAT1 on the regulation the human hsp90 alpha gene expression].

OBJECTIVE: To investigate the role of STAT1 on the regulation of human hsp90 alpha gene expression. METHODS: We first transfected Jurkat cells with the STAT1 expression construct and analyzed the expression of hsp90 alpha gene expression via quantitative RT-PCR system. Then we co-transfected the STAT1 expression construct and the CAT reporter gene driven by different length of 5' flanking sequence of hsp90 alpha gene. Western blot was carried out to detect the level of tyrosine phosphorylation in Jurkat cells with and without heat shock treatment (42 degrees C 1 h). By electrophoretic mobility shift assays (EMSA), we evaluated the DNA binding activity of a STAT1 responsible element located in the regulatory region of hsp90 alpha gene in Jurkat cell nuclear extracts. RESULTS: The mRNA level of hsp90 alpha gene in Jurkat cells was decreased when transfected by STAT1 expression construct, over-expression of STAT1 down-regulates the expression of CAT reporter gene with the present of a distal fragment from -1756 to -1463 within the 5' flanking regulatory sequences of hsp90 alpha gene. The tyrosine phosphorylation of STAT1 was detectable in Jurkat cells and increased when subjected to heat shock. Electrophoretic mobility shift assays (EMSA) results showed that STAT1 could bind to its responsible element in the regulatory region of hsp90 alpha gene. CONCLUSION: STAT1 could negatively regulate the human hsp90 alpha gene expression.

DNA-Binding Proteins↗
PubMed2001

[Gene expression changes after heat shock by cDNA array analysis].

OBJECTIVE: To study gene expression changes of cells in response to heat stress, we isolated total RNA from Jurkat cells before and after heat shock treatment. METHODS: cDNA was labeled with alpha-32P-dATP during reverse transcription of RNA and then used as probe to cDNA expression array. Autoradiogram images were analyzed by ESTblot software. RESULTS: After heat shock, the expression level of some forty genes increased while that of sixteen genes decreased. In addition to the elevated expression of heat shock genes, expression of c-Jun and CLK-1 increased most remarkably. The genes with notably decreased expression were integrin alpha-4 and transforming growth factor beta. The elevated expression of c-Jun and hsp90 alpha was further confirmed by Northern blot analysis. CONCLUSIONS: The expression of some genes in Jurkat cells changes after heat shock treatment. Heat shock induces elevated expression of hsp, c-Jun, CLK-1 gene while decreases expression of integrin alpha-4 and transforming growth factor beta.

Blotting, Northern↗
PubMed2000

Extracoronal resilient attachments in distal-extension removable partial dentures.

Esthetics is often compromised in patients who wear removable partial dentures with metal clasps placed on anterior teeth. Clinical procedures are presented for a new design of a removable partial denture that improves esthetics and function through a new dental attachment. The extracoronal resilient attachment system offers vertical resiliency and universal stress relief for use where a resilient prosthesis is indicated. The removable partial denture retained by these attachments provides esthetics, vertical resiliency, and easy replacement of worn attachments.

Dental Abutments↗
PubMed2000

[The development of a 64-channel epicardial potential mapping system].

A 64-channel epicardial potential mapping system was developed in order to study the mechanics of arrhythmia such as atrial fibrillation and ventricular fibrillation, and instruct the procedure of detecting and eliminating abnormal rhythm in experiment or clinic. The system was consist of electrode, amplifier, A/D card, computer and output device. The system's software include signal acquisition module, signal preprocessing module, character-point detecting module, isochrone-map construction module, output display and print module. The system could be used to detect the activation path of atrial fibrillation and ventricular fibrillation.

Algorithms↗
PubMed1999

Regulation of human hsp90alpha gene expression.

Mammalian HSP90alpha and HSP90beta are encoded by two individual genes. On the basis of the upstream sequences of the human hsp90alpha gene, GenBank accession number U25822, we have constructed CAT reporter plasmids driven by individual fragments of the hsp90alpha gene. We found that (1) the proximal heat shock element complex located at -96/-60 enhances hsp90alpha promoter expression; (2) heat shock induction depends upon the coexistence of distal heat shock element at -1031/-1022 and the proximal heat shock element complex of the hsp90alpha gene; (3) unlike hsp90beta, downstream sequences of the transcription start site inhibit hsp90alpha expression. We conclude that the regulatory mechanisms for the expression of hsp90alpha and hsp90beta genes are different.

Binding, Competitive↗
PubMed1999

Soft tissue management using palatal mucosa around endosteal implants in vascularized composite grafts in the mandible.

Excessive thickness and mobility of the skin flap and lack of a vestibular sulcus in composite vascularized bone grafts for mandibular reconstruction limit the usefulness of endosteal implants to support a prosthetic device. Palatal mucosal grafts and a simple acrylic stent are an excellent means to overcome these problems. The technique is presented in this paper.

Acrylic Resins↗
PubMed1998

Primary insertion of osseointegrated dental implants into fibula osteoseptocutaneous free flap for mandible reconstruction.

Twelve patients with segmental mandibular defects were reconstructed with fibula osteoseptocutaneous flaps and simultaneous placement of osseointegrated implants. Decision to perform this procedure was based on the facts that all patients had benign diseases, did not require postoperative radiotherapy, were in good general and oral conditions, and were psychologically motivated. A total of 34 fixtures was inserted in the first stage. Eight patients underwent second stage surgery, which consisted of connection of the implant abutments to the fixtures and the use of palatal mucosal grafts around the implants. Final dental prostheses were fixed 1 month later in seven patients, at this time. All flaps survived after surgery, and no implant failure was observed after a mean follow-up period of 25 months. Only one fixture was not used during the subsequent stage and was left as a sleeper. Fixed dental prostheses were used in five patients and removable overlay prostheses in the other two. Chewing function was recovered between 4 and 6 weeks after the start using the definitive dental prosthesis. In contrast to previous results, we conclude that excellent results can be achieved when this combined procedure is used in carefully selected patients. In addition, it is confirmed that the fibula osteoseptocutaneous flap is a versatile, reliable composite tissue that facilitates primary placement of osseointegrated dental implants during mandible reconstruction, thus allowing full oral rehabilitation in a shorter period of time.

Adolescent↗
PubMed1996

Implant-retained mandibular overdentures: a simplified effective treatment option.

The use of implant-retained mandibular overdentures is a treatment option for compromised patients. The combination of using a bar and intracoronal attachments to connect two implants provides cross-arch stabilization, good retention and stability for the overdenture which is still mainly supported by soft tissue. However, connecting the component parts of an internal attachment to the removable overdenture requires numerous laboratory and clinical procedures and the resulting errors can prevent proper seating of the prosthesis. A simple, direct technique, totally controlled by the operator, is presented to increase the precision of the assemble of the component parts and contribute to the precise fit if the implant-retained overdenture. The advantages, disadvantages and the rational treatment are discussed.

Dental Implants↗