Biomedical subjects

Wei Chen

Publications and source records attributed to Wei Chen.

530 records · Page 30Linked to original sources

PubMedDate not supplied

Clinicopathologic features and results of transcatheter arterial chemoembolization for osteosarcoma.

PURPOSE: To evaluate the effect of transcatheter arterial chemoembolization (TACE) for osteosarcoma and to describe the clinicopathologic features produced by TACE as well as the effect of different embolic materials. METHODS: From January 1998 to December 2003, preoperative TACE was carried out in 32 patients. The preoperative and postoperative clinical response, levels of alkaline phosphatase (AKP), leukocyte count, and clinicopathologic features were recorded. We also compared the effect of different embolic materials: adriblastine gelatin microspheres, anhydrous alcohol, common bletilla tuber, and gelatin sponge particles. RESULTS: The levels of AKP were significantly decreased after treatment (p < 0.05), but there was no significant difference in the leukocyte count. Large areas of necrosis were found histologically within 85.5% tumors after TACE. Embolic agents such as adriblastine microspheres, anhydrous alcohol, and common bletilla tuber have better clinical effects than gelatin sponge particles, but there was no significant difference among the first three embolic materials. After treatment, no serious complications were noted. During successful follow-up for 86 months, the survival rate after TACE at 1, 2, and 5 years was 95.5%, 72%, and 42% respectively. CONCLUSION: TACE accelerated tumor necrosis and shrank the tumor volume, thus making adequate tumor resection possible. The optimal time to operate is 10-14 days after TACE. TACE in combination with limb salvage surgery and postoperative periodical chemotherapy may be beneficial for increasing local control rates.

Adolescent↗

PubMedDate not supplied

Water-soluble degradable hyperbranched polyesters: novel candidates for drug delivery?

A novel approach to hyperbranched polymers is presented in this work. Hyperbranched polyesters with a large amount of terminal hydroxyl groups are prepared by a one-pot synthesis from commercially available AB-type and CD(n)-type monomers (n >/= 2). In this paper, Michael addition of diethanolamine (CD(2)) or N-methyl-d-glucamine (CD(5)) to methyl acrylate (AB) generates dominantly AD(n)-type intermediates. Further self-condensation of intermediates at higher temperature and in the presence of catalyst gives hyperbranched polyesters. Because of the tertiary amino groups in the backbone and the hydroxyl groups in the linear and terminal units, the resulting hyperbranched polyester is highly soluble in water. Furthermore, the hyperbranched polymer is degradable because of its ester units. So, the water-soluble hyperbranched polyesters might be applied as a novel material for drug delivery.

Biodegradation, Environmental↗

PubMedDate not supplied

Identification of symmetries in molecules and complexes.

An algorithm is presented that quickly detects local and global symmetries of single molecules and complexes. Based upon the Morgan Naming Algorithm, the algorithm involves traversing the molecule from a starting atom and building up a molecule name based upon the names of the atoms encountered along the traversal. Additional molecule names are generated from other starting atoms, and name-name matches are identified as corresponding to symmetry operations. A number of enhancements relative to prior methods yield increased efficiency and extended functionality. In particular, the present method detects not only global symmetries but also local symmetries associated with bond rotations as well as symmetries that are only apparent when alternate resonance forms are considered. Importantly, the present method works not only for single molecules but also for multimolecular complexes. As a consequence, it is well, and perhaps uniquely, suited to applications in supramolecular and host-guest chemistry. Applications include filtering out redundant conformations during conformational searching and free energy calculations; accelerating ligand-receptor docking calculations by reducing the sampling ranges of rotatable bonds linked to locally symmetric groups, such as phenyls; and automating the calculation of symmetry numbers for thermochemical applications.

Algorithms↗

PubMedDate not supplied

Achieving antigen-specific tolerance in diabetes: regulating specifically.

Autoreactive T cells that escape negative selection in the thymus do not normally cause productive immune responses to self-antigens because of a number of regulatory mechanisms. Studies with anti-CD3 monoclonal antibodies (mAbs) have suggested that immune regulatory mechanisms are induced by drug treatments that are able to stop on-going unwanted immune responses, such as type 1 diabetes, involving induction of regulatory T cells. TGF-beta dependent and independent mechanisms have been described involving CD4(+) as well as CD8(+) T cells. The challenge is now to apply these mechanisms in an antigen-specific manner and so that lasting tolerance to the autoimmune responses can be maintained. We discuss recent data concerning the mechanisms of anti-CD3 mAb treatment and the ways in which our understanding of these mechanisms can be used to develop adoptive immune therapy with regulatory T cells to treat patients with type 1 diabetes or other autoimmune diseases.

Antibodies, Monoclonal↗

PubMedDate not supplied

Ontogeny of expression of transforming growth factor-beta and its receptors and their possible relationship with scarless healing in human fetal skin.

Fetal cutaneous wounds that occur in early gestation heal without scar formation. Although much work has been done to characterize the role of transforming growth factor-beta (TGF-beta) isoforms and their receptors in the wound healing process, their roles in scarless wound repair observed in early gestation and their functions in human fetal skin development, and structural and functional maintenance are still not well understood. In this study, we explore the expression and distribution characteristics of three TGF-beta isoforms and their receptors, TGF-betaRI (TBRI) and TGF-betaRII (TBRII), in fetal and postnatal skins to understand the relevance of these five proteins to skin development and elucidate the mechanism(s) underlying the phenotypic transition from scarless to scar-forming healing observed during fetal gestation. Fetal skin biopsies of human embryo were obtained from spontaneous abortions at different gestational ages from 13 to 32 weeks and postnatal skin specimens were collected from patients undergoing plastic surgery. Gene expression and positive immunohistochemical signals of TGF-beta(1), TGF-beta(2), TGF-beta(3), TBRI, and TBRII could all be detected in fetal and postnatal skins. In early gestation, gene expression of TGF-beta(1), TBRI, and TBRII was weaker and protein contents were less compared with postnatal skins (p < 0.05). In contrast, more TGF-beta(2) mRNA transcript was found in early gestation than in late gestation and in postnatal skins, whereas protein content of this growth factor increased during gestation. Lastly, mRNA transcript and protein contents of TGF-beta(3) were apparently higher in early gestation compared to postnatal skin (p < 0.05). In postnatal skin, granules containing the three TGF-beta isoforms were mainly distributed in the cytoplasm and extracellular matrix of epidermal cells, interfollicular keratinocytes, and some fibroblasts. TBRI and TBRII were chiefly located in the cellular membrane of epidermal keratinocytes and some fibroblasts. The endogenous three TGF-beta isoforms and their receptors may be involved in the development of embryonic skin and in the maintenance of cutaneous structure and function, and also in postnatal wound healing. The differential levels of TGF-beta isoforms may provide either a predominantly antiscarring or profibrotic signal upon wounding depending on the gestational period. Lower expression of their receptors in early gestational skins may be a reason for the reduced ability to perceive ligands, ultimately leading to scar-free healing.

Cicatrix↗

PubMedDate not supplied

Engineered growth factors and cutaneous wound healing: success and possible questions in the past 10 years.

In the past 10 years, many engineered growth factors, including recombinant human epidermal growth factor, basic fibroblast growth factor, and platelet-derived growth factor, have been produced and used in the clinic. After screening the results from different centers, some results are found to be encouraging, while others are discouraging. Although the interpretation of these results may depend on your perspective, it may also depend on different criteria, different wounds, and even different aims. In this article, successful experiences and failures concerning the use of growth factors and cutaneous wound healing are summarized. Based on this information and our clinical experience, we address people's concerns such as whether growth factors have altered clinical practice thus far and whether growth factor treatments have solved all problems involved in wound healing. Is there a need for exogenous application of growth factors in acute or chronic wounds, and if so, is it safe to use growth factors to promote wound healing? Last, can we achieve perfect wound healing in those wounds treated with growth factors?

Drug Delivery Systems↗

PubMedDate not supplied

A program for evaluating dual-equilibrium desorption effects on remediation.

Desorption is one of the most critical processes affecting the effectiveness of soil and ground water remediation. None of the currently adopted desorption models can accurately quantify desorption of low-hydrophobicity organic chemicals, and thus could potentially mislead remediation design and decision-making. A recently developed dual-equilibrium desorption (DED) model was found to be much more accurate in quantifying desorption. A screening-level transport model, DED-Transport, was developed to simulate the DED effect on behaviors of organic contaminant plumes during remediation. DED-Transport requires only simple parameters, but is applicable to many remediation scenarios. DED-Transport can be used as a decision-support tool in site remediation to more precisely predict the time required for cleanup.

Adsorption↗

PubMedDate not supplied

Automated lamellar keratoplasty for recurrent granular corneal dystrophy after phototherapeutic keratectomy.

PURPOSE: To evaluate the safety and efficacy of automated lamellar keratoplasty for the treatment of recurrent granular corneal dystrophy after phototherapeutic keratectomy (PTK). METHODS: We performed a prospective interventional noncomparative case study of nine eyes (seven patients) with severe recurrent granular corneal dystrophy after PTK. An automated microkeratome was used to cut partial-thickness sections through the anterior surface of the donor and host corneas. The donor disc was placed on the recipient bed with four or eight interrupted sutures. The sutures were removed between 4 and 6 weeks postoperatively. Visual acuity, corneal clarity, corneal thickness, and corneal topography were assessed before and at different time points after surgery. RESULTS: During a mean follow-up period of 18.9 +/- 4.1 months, all grafts were transparent without visible opacity at the interface, and no serious complications occurred. In all cases, the visual acuity improved: seven eyes had best spectacle-corrected visual acuity of > or = 20/40; two eyes reached 20/25. At last follow-up > 12 months postoperatively, the mean corneal refractive power had significantly increased by 2.34 +/- 0.93 diopters (D) (P<.001), and the corneal astigmatism significantly decreased by 0.91 +/- 0.98 D (P<.05). The mean corneal thickness was 477.4 +/- 26.9 microm preoperatively and 507.8 +/- 23.4 microm at last follow-up (P<.001). CONCLUSIONS: Our findings suggest that automated lamellar keratoplasty for the treatment of recurrent granular corneal dystrophy is a safe and effective method of improving visual acuity, but recurrence remains a risk.

Adult↗