Biomedical subjects

Lie Ma

Publications and source records attributed to Lie Ma.

12 recordsLinked to original sources

PubMed2007

Compressed oxygen in drug stability experiments.

A drug stability experiment accelerated by compressed oxygen was established. The stability of 10% ascorbic acid solution as a model was studied and the kinetic parameters were obtained with the newly established experimental method. Because ascorbic acid degrades under both anaerobic and aerobic conditions, the total rate constant k(total) can be expressed as: k(total)=k(anaerobic) + k(aerobic), where k(anaerobic) and k(aerobic) are the rate constants of anaerobic and aerobic degradations, respectively. The k(anaerobic) can be expressed as k(anaerobic) = A(anaerobic) x exp(-E(a,anaerobic)/RT) according to Arrhenius equation, and the k(aerobic) was found to be k(aerobic) = A(aerobic) x exp(-E(a,aerobic)/RT) x p(O2) in our study.

Ascorbic Acid↗

PubMed2006

[The factors associated with viral relapse after interferon treatment in chronic hepatitis C patients].

OBJECTIVE: To investigate the relationship between hepatitis C virus (HCV) genotype, serum viral load and ALT levels, and the factors associated with the viral relapse after IFN treatment in patients with chronic hepatitis C. METHODS: The HCV RNA levels were determined with Cobas Amplicor Monitor Test, version 2.0, and HCV genotypes were examined by means of PCR products of 5' NTR digested with restriction endonucleases. The patients with chronic hepatitis C were treated with PEG-IFN alpha -2a and Roferon-A for 24 weeks. Those with a viral response after 24 week treatment were followed for an additional 24 weeks. The association of clinical characteristics, such as sex, age, the way of the HCV infection, IFN treatment history and platelet counts, and the HCV genotype, virus load and medicine used for the viral relapse after IFN treatment were analyzed. RESULTS: Of the 208 chronic hepatitis C patients, the ALT levels were not related to HCV RNA levels (r = 0.093, P > 0.05). No difference of ALT levels between HCV genotypes was found, and the HCV RNA load was also of no difference between HCV genotype 1 patients and non 1 patients. Of the 119 patients with viral response after 24 week treatment, 58 cases (48.7%) relapsed after another 24 week's follow-up. Relapse was not significantly related to the clinical characteristics, such as sex, age, mode of the infection, treatment history of IFN, AST/ALT ratio, platelet counts and the baseline viral load. Among patients with genotype 1 virus, the relapse rate was significantly higher than those patients with non-genotype 1 virus (54.5% vs 32.1%, P=0.039). The relapse rate after PEG-IFN alpha -2a treatment was lower than that of Roferon-A treatment (47.0% vs. 52.8%), but not significantly. CONCLUSION: The viral relapse of chronic hepatitis C patients after IFN treatment was significantly associated with the genotypes of the HCV.

Antiviral Agents↗

PubMed2005

Preformed microcapsules for loading and sustained release of ciprofloxacin hydrochloride.

A novel pathway for ciprofloxacin hydrochloride delivery system based on spontaneous deposition mechanism was introduced with respect to encapsulation, quantitative drug loading and sustained release. Layer-by-layer assembly of oppositely charged polyelectrolytes onto melamine formaldehyde (MF) colloidal particles, followed by removal of the cores at low pH has yielded hollow microcapsules having a unique property to induce spontaneous deposition of various water-soluble substances. Observations under scanning electron microscopy, atomic force microscopy and transmission electron microscopy provided direct proofs of the spontaneous deposition. The quantitative drug loading and sustained release properties were elucidated. Results show that the loaded drug is proportional to drug feeding concentrations, temperature and salt concentrations, demonstrating tailorable deposition behavior that is crucial for the drug carrier. The deposited ciprofloxacin hydrochloride could be again released in a sustained manner and exhibited a significant antiseptic activity with high biocompatibility.

Anti-Bacterial Agents↗

PubMed2005

[Primary study on histocompatibility of three kinds of collagen-chitosan porous scaffolds].

OBJECTIVE: To construct three kinds of collagen-chitosan porous scaffolds with enhanced bio-stability and to investigate the histocompatibility of the scaffolds in vivo. METHODS: Collagen-chitosan porous scaffolds were fabricated by freeze-drying method, cross-linked using dehydrothermal treatment and glutaraldehyde, respectively. The morphology of the uncross-linked scaffold (scaffold 1), dehydrothermal cross-linked scaffold (scaffold 2) and glutaraldehyde cross-linked scaffold (scaffold 3) was studied by scanning electron microscopy. Three kinds of scaffolds were embedded subcutaneously on dorsal surface of 12 rabbit ears. The general and local responses were recorded daily. The bio-stability and histocompatibility of the scaffolds were observed by using HE staining after 3, 7, 14 and 28 days of operation. RESULTS: The scaffolds had three-dimensional porous structures with a porosity of more than 90%, and possessed pore sizes of 120 +/- 10 microm, 80 +/- 15 microm and 170 +/- 20 microm, respectively. All experimental rabbits survived with good general condition during the study. All skin incisions healed well without obvious reactive red or swelling. Histological study showed that scaffold 1 was degraded rapidly with obvious inflammation. The degradation of scaffold 2 was slower than that of scaffold 1 and the inflammation of scaffold 2 was also milder than that of scaffold 1. Scaffold 3 possessed slow degradation property with slight inflammatory reaction, and rapid tissue regeneration. CONCLUSION: The collagen-chitosan porous scaffolds have three-dimensional porous structures that are suitable for tissue regeneration. The bio-stability and histocompatibility of the scaffolds are enhanced after cross-linked. Glutaraldehyde cross-linked is better than dehydrothermal cross-linked, which can facilitate dermal tissue reconstruction.

Animals↗

PubMed2004

Biodegradability and cell-mediated contraction of porous collagen scaffolds: the effect of lysine as a novel crosslinking bridge.

A novel crosslinking method was adopted to modify the porous collagen scaffolds by using a water-soluble carbodiimide, 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide (EDAC) and N-hydroxysuccinimide (NHS) in the presence of lysine, which functions as a crosslinking bridge. In vitro biodegradation tests proved that in the presence of lysine the biostability of the EDAC crosslinked scaffolds was greatly enhanced. The biostability of the resultant scaffolds was also elucidated as a function of the concentrations of lysine and EDAC/NHS. Compared to the Col-DHT, the ability of the Col-EDAC and the Col/Lys to resist cell-mediated contraction (CMC) was greatly enhanced. Yet no obvious difference between the Col-EDAC and the Col/Lys was found with respect to CMC. SEM observations showed that the microstructure of the crosslinked scaffolds could be largely preserved after fibroblast seeding. As a result, MTT assays proved that the fibroblasts in the Col/Lys scaffolds proliferated faster compared to the DHT-treated one on the assumption that the cell viability was preserved to a similar level. Histological section results indicated that the Col/Lys scaffolds had the ability to accelerate the cell infiltration and proliferation. All these results demonstrated that this novel crosslinking method is an effective way to achieve a collagen scaffold with improved biostability and a more stable structure, which can resist cell-mediated contraction. (c) 2004 Wiley Periodicals, Inc. J Biomed Mater Res 71A: 334-342, 2004.

Animals↗

PubMed2004

Enhanced biological stability of collagen porous scaffolds by using amino acids as novel cross-linking bridges.

Collagen porous scaffolds have been widely employed as a dermal equivalent to induce fibroblasts infiltration and dermal regeneration. To eliminate the disadvantageous drawback of the fast degradation speed, a cross-linking method was adopted by using a water-soluble carbodiimide, 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide (EDAC) and N-hydroxysuccinimide (NHS) in the presence of amino acids (glycin, glutamic acid or lysine), which function as cross-linking bridge between collagen molecular chains. In vitro assessment of the biological stability of the cross-linked collagen scaffolds found that the collagenase biodegradation degree was greatly decreased when lysine was added, resulting in a more biological stable scaffold. On the other hand, the biodegradation degree was accelerated compared with the purely cross-linked when glutamic acid was added, while less influenced by glycin addition. By comparing the biodegradation degree of the scaffolds added with amino acids and their model compounds, i.e. adipic acid and hexane diamine, the key factor influencing the biological stability was further investigated. The results indicated that the crucial factor is dependent on the ratio of amino groups to carboxyl groups in the cross-linking system. At optimal ratio the lowest biodegradation degree is achieved. Scanning electron microscopy measurements prove that the three-dimensional structure of the scaffolds was largely preserved. Preliminary in vitro culture of fibroblasts in the collagen scaffold cross-linked with EDAC/NHS in the presence of lysine has shown that the original good cytocompatibility of collagen was retained.

Amino Acids↗

PubMed2004

[Skin-like structure generated from implantation of hair follicle bulb cells into collagen/chitosan porous scaffolds in vitro].

OBJECTIVE: To observe the skin regeneration after hair follicle bulb cells were implanted into collagen/chitosan porous scaffolds in vitro. METHODS: The cultured dorsal hair follicle bulb cells of 4d-old C57BL/6J mice were implanted into collagen/chitosan porous scaffolds in vitro. The skin regeneration was observed. RESULT: The skin-like structure was formed on the collagen/chitosan porous scaffolds where were cultured the hair follicle bulb cells before 4th passages. CONCLUSION: The skin-like structure is generated in vitro when early passages of cultured hair bulb cells are implanted into collagen/chitosan porous scaffolds.

Animals↗

PubMed2004

[Factors controlling the microstructure of collagen-based dermis regeneration scaffold].

The factors controlling the microstructure and properties of collagen-based bioactive artificial dermis are reviewed. The second component, the pore diameter and porosity, the thickness of scaffold, the bioactive factors as well as the cross-linking density that are important parameters of artificial dermis should be carefully researched and designed. Experiment methods controlling these parameters are suggested.

Biocompatible Materials↗

PubMed2004

[Difference and significance of T-lymphocyte subsets in differential diagnosis between severe acute respiratory syndrome and common atypical pneumonia].

BACKGROUND: To clarify the difference and significance of T-lymphocyte subsets in differential diagnosis between severe acute respiratory syndrome SARS) and common atypical pneumonia. METHODS: Totally 100 patients hospitalized in Beijing Ditan Hospital since March to June 2003 with clinical diagnosis of SARS were involved in this study. These patients courses of disease were over 3 weeks. These patients were divided into two groups, SARS group and common atypical pneumonia group (non-SARS group). The counts of CD3+, CD4+ and CD8+ T-lymphocyte of two groups were systematically recorded and analyzed. RESULTS: Sixty-five of the patients were confirmed to have common type of SARS, including 26 males and 39 females, 50 cases received methylprednisolone treatment. Thirty-five cases had common atypical pneumonia (non-SARS), 21 were males while 14 were females, 20 cases received methylprednisolone treatment. All the cases of two groups were cured in the end. The SARS patients T-lymphocyte counts decreased first and then increased. Before 15 days of disease course, mean CD3+, CD4+, CD8+ T-lymphocyte counts of SARS patients were decreased apparently (694+/-568/microl, 441+/-356/microl, 309+/-462/microl). After 15th day of disease course, the counts gradually returned to normal CD3+, CD4+, CD8+ T-lymphocyte counts of non-SARS patients were normal. Compared with patients of the same group who were not treated with glucocorticoids, T-lymphocyte counts of non-SARS patients treated with glucocorticoids had no obvious difference. But glucocorticoids had some effect on SARS patients recovery of cellular immune function, i.e., it delayed the recovery by about 6 days. CONCLUSION: With or without treatment with glucocorticoids,the lowered CD3+, CD4+, CD8+ T-lymphocyte counts in the early stage are of very important significance in differential diagnosis between severe acute respiratory syndrome and common atypical pneumonia.

Adult↗

PubMed2003

Collagen/chitosan porous scaffolds with improved biostability for skin tissue engineering.

Porous scaffolds for skin tissue engineering were fabricated by freeze-drying the mixture of collagen and chitosan solutions. Glutaraldehyde (GA) was used to treat the scaffolds to improve their biostability. Confocal laser scanning microscopy observation confirmed the even distribution of these two constituent materials in the scaffold. The GA concentrations have a slight effect on the cross-section morphology and the swelling ratios of the cross-linked scaffolds. The collagenase digestion test proved that the presence of chitosan can obviously improve the biostability of the collagen/chitosan scaffold under the GA treatment, where chitosan might function as a cross-linking bridge. A detail investigation found that a steady increase of the biostability of the collagen/chitosan scaffold was achieved when GA concentration was lower than 0.1%, then was less influenced at a still higher GA concentration up to 0.25%. In vitro culture of human dermal fibroblasts proved that the GA-treated scaffold could retain the original good cytocompatibility of collagen to effectively accelerate cell infiltration and proliferation. In vivo animal tests further revealed that the scaffold could sufficiently support and accelerate the fibroblasts infiltration from the surrounding tissue. Immunohistochemistry analysis of the scaffold embedded for 28 days indicated that the biodegradation of the 0.25% GA-treated scaffold is a long-term process. All these results suggest that collagen/chitosan scaffold cross-linked by GA is a potential candidate for dermal equivalent with enhanced biostability and good biocompatibility.

Animals↗

PubMed2003

Thermal dehydration treatment and glutaraldehyde cross-linking to increase the biostability of collagen-chitosan porous scaffolds used as dermal equivalent.

A biodegradable scaffold for skin-tissue engineering was designed using collagen and chitosan, which are common materials for biomedical application. The scaffolds containing different amounts of chitosan were prepared by mixing the collagen and chitosan solutions followed by removal of the solvent using a freeze-drying method. The cross-linking treatment of these scaffolds was performed using the dehydrothermal treatment (DHT) method or glutaraldehyde (GA) to increase their biostability. The effect of the chitosan concentration and the cross-linking methods on the morphology of these scaffolds was studied by SEM. The water retention and the biodegradability in vitro of various collagen-chitosan scaffolds were investigated. Finally the biocompatibility of the collagen-chitosan (10 wt% chitosan) scaffold treated with different cross-linking methods was evaluated using a in vivo animal test. A mild inflammatory reaction could be detected in the early stages, and GA treatment can decrease the inflammatory reaction in a long-term implantation. After implantation for four weeks, all kinds of scaffolds, especially the GA-treated scaffolds (Col-GA) were filled with a large number of fibroblasts and were vascularized to a certain extent. These results suggest that the GA-treated scaffold has an increased biostability and excellent biocompatibility. It can be a potential candidate for skin-tissue engineering.

Administration, Cutaneous↗

PubMedDate not supplied

Bioactive thin film of acidic fibroblast growth factor fabricated by layer-by-layer assembly.

A new class of bioactive thin films using growth factors as building blocks has been fabricated via layer-by-layer assembly (LBL) technique. Acid fibroblast growth factor (aFGF) in the presence of heparin was used as negatively charged polyelectrolytes, while poly(ethyleneimine) (PEI) was chosen as a positively charged counterpart. The self-deposition process and surface morphology of the resultant multilayers were monitored and detected by UV-vis absorbance spectra, advanced contact angle measurements, and scanning force microscopy (SFM) observations. Cell culture was performed to assess the efficiency of the growth factors. The fibroblasts proliferated faster on the surface assembled with five bilayers of (aFGF/heparin)/PEI with apparent higher cytoviability than on those surfaces modified by one bilayer of (aFGF/heparin)/PEI, five bilayers of aFGF/PEI, or five bilayers of heparin/PEI, and tissue culture polystyrene. Enhanced secretion of collagen type I and interleukin 6 (IL-6) by the fibroblasts seeded on the five bilayers of (aFGF/heparin)/PEI was also verified by immunohistochemical examination. The bioactivity of the (aFGF/heparin)/PEI multilayers could be largely preserved when stored at -20 degrees C.

Cell Proliferation↗