Biomedical subjects

S Li

Publications and source records attributed to S Li.

At least 757 records · Page 42Linked to original sources

PubMed1999

[Rapid determination of cefazolin in porcine serum by high performance capillary electrophoresis].

A rapid high performance capillary electrophoretic method was established to assay cefazolin in porcine blood serum. Porcine serum was deproteined by 60% acetonitrile and superlants were injected with 10 s pressure load. The final assay condition was: 40 cm x 75 microns silica capillary, 50 mmol/L bicarbonate buffer at pH10, 20 kV for 5 min, 254 nm UV detection. The assay was linear within the range of 5-320 micrograms/ml, the intra-day and inter-day relative standard deviations ranged from 1.7% to 8.0%. Analytical recovery of cefazolin was 107.9%, the limit of detection was 1.5 micrograms/ml, the limit of quantitation was 3.6 micrograms/ml. To investigate the pharmacokinetic profile of cefazolin in pig, six adult pigs were injected with 16 mg/kg cefazolin and all data was analyzed by pharmacokinetic software 3P87. Cefazolin metabolism in adult pigs appeared to be a typical two-compartment model with a clearance of 8.43 ml/(kg.min).

Animals↗

PubMed1999

[Immunogenicity and immunoprotection of a leptospiral DNA vaccine].

Leptospirosis is one of the most widespread zoonosis. Immunization of NZW rabbit with plasmid DNA constructs encoding leptospiral endoflagellin can induce specific antibody response in the animal. The vector, VR1012 consists of a pUC18 backbone with the cytomegalovirus (CMV) IE1 enhancer, promoter, and intron A transcription regulatory elements and the BGH polyadenylation sequences driving the expression of leptospiral endoflagellar gene, flaB2. In this study, a pair of oligonucleotide primers were designed to amplify the endoflagellar of L. interrogans serovar lai. An approximately 840 bp fragment was generated with PCR and inserted into expressed plasmid vector, VR1012, after the fragment of VR1012 were digested respectively with EcoRV and Sall. A recombinant plasmid (designated VR1012 + flaB2) was obtained. Plasmid encoding leptospiral endoflagellin was injected into quadriceps of NZW rabbits. This resulted in the generation of specific leptospiral antibody with very high ELISA titer. Immunoprotection was performed in guinea pigs. The group "VR1012 + flaB2" had higher survival rate, compared with the group "VR1012 only" (control) and the group "Normal Saline only" (control). The result suggests that the technique of DNA injection should have an advantage over certain previous vaccine technologies.

Animals↗

PubMed1999

[Effects of yi qi tong mai oral liquid on acute myocardial ischemia in dogs].

The objective of this study was to assess the prophylactic and therapeutic effects of Yi Qi Tong Mai Oral Liquid (YQTMOL) on acute myocardial ischemia. The models of ischemia were made, in which the anterior coronary arteries of anesthetized dogs were ligated. Four groups of dogs were examined and compared. We determined the extent of their myocardial ischemia and infarction by means of epicardial mapping and N-BT staining. The results showed that in the treatment groups, the increase of sigma-ST was inhibited 30-180 minutes after the oral administration of YQTMOL(compared with control group, P < 0.01), and the sigma-ST was decreased (P < 0.05). Furthermore, in the group dosed with YQTMOL (10 g/kg), the ratios of "area of infarction/heart weight" and "area of infarction/ventricle weight" both decreased (compared with control group, P < 0.05). These findings indicated that YQTMOL reduced the area of myocardial ischemia and the degree of myocardial infarction in dogs, so it could be effective for the prevention and treatment of acute myocardial ischemia.

Animals↗

PubMed1999

[Clinical usefulness of serum IFN-gamma level in patients with chronic obstructive pulmonary disease].

The objective of this study was to gain a clear idea of rule of change in serum IFN-gamma level in patients with chronic obstructive pulmonary disease and to evaluate the clinical usefulness of IFN-gamma as a marker of immune condition. The serum IFN-gamma levels of 15 patients with chronic bronchitis, 15 patients with cor pulmonale, 15 patients with acute bronchitis, and 15 normal subjects were measured by radio-immuno-assay. Differences between the four groups were tested, and in the chronic bronchitis group, the serum IFN-gamma levels, before and after treatment were compared. The results showed that compared with the normal group (0.8 +/- 0.17 IU/ml), the serum level changed little in the cor pulmonale group (0.93 +/- 0.25 IU/ml); it was not higher in the chronic bronchitis group (1.23 +/- 0.39 IU/ml, P > 0.05), but it went up significantly after treatment for 7 days (1.84 +/- 0.51 IU/ml, P < 0.05). The highest level of IFN-gamma was noted in the acute bronchitis group (2.24 +/- 0.71 IU/ml, P < 0.01). There was a significant difference compared with other groups (P < 0.01). These results suggest that relative deficiency of serum IFN-gamma may be a factor inducing repeated respiratory infection, and the serum level of IFN-gamma can be used as an index to assess the immune condition of patients with chronic obstructive pulmonary disease.

Biomarkers↗

PubMed1999

[Determination of alkaloids in radix Sophorae flavescentis by high performance capillary electrophoresis].

OBJECTIVE: To develop a simple and rapid method for the determination of alkaloids in Radix Sophorae Flavescentis (RSF). METHOD: HPCE buffer: 20 mmol.L-1 phosphates, pH 7.0; V = 20 kV, leff = 50 cm, L = 64.5 cm, i.d. = 50 microns, lambda = 201 nm, T = 25 degrees C, sample size = 10 kPa.s. RESULT: Matrine(I) and oxymatrine(II) in RSF were completely separated with recoveries of 97.47% and 97.67% respectively. CONCLUSION: Simple, accurate and reproducible, this method can be used for the quality control of Chinese herbal medicines.

Alkaloids↗

PubMed1999

[Role of apoptosis and bcl-2 gene in the temporomandibular joint development].

OBJECTIVE: Apoptosis involving in embryogenesis and organ formation has been verified, but the possible roles of apoptosis and its related regulative genes have not been clarified. Temporomandibular joint dysfunction (TMD) has increased in incidence and occurred increasingly in young patients. Thus, research on the development and gene modulation is necessary. METHODS: Tdt-mediated dUTP nick end labeling (TUNEL) and mRNA in situ hybridization were used in observation of apoptosis and bcl-2 gene expression in TMJ of SD rats during prenatal and postnatal developmental period. RESULTS: Apoptosis involved in different development periods of condylar cartilage, and the cells of apoptosis mainly located in the proliferative zone and the area between the prehypertrophic zone and the late hypertrophic zone., bcl-2 was expressed in chondrocytes throughout condylar cartilage with high levels in proliferative and prehypertrophic chondrocytes and obvious low levels in the late hypertrophic chondrocytes. Very few matured chondrocytes expressed bcl-2. CONCLUSION: Apoptosis regulated by bcl-2 plays an important role in prenatal and postnatal development of TMJ.

Animals↗

PubMed1999

[Analysis of 413 cases of mandibular fractures].

OBJECTIVE: To investigate the characteristics of mandibular fracture. METHODS: 413 patients with mandibular fracture were chosen from patients who received treatment at the department of oral and maxillofacial surgery, College of Stomatology, West China University of Medical Sciences from 1986 to 1995, and a retrospective study was carried out. Chi-square test, t-test and linear regression were used to analyzed age, sex, causes, anatomic site, complicated injury, and treatment of jaw fracture. RESULTS: Fracture of Mandible occurred mainly in male, and during 20 to 29 years old. Mental fracture was common in mandibular fracture, and fracture of central craniofacial bone and craniocerebral injury were often complicated with jaw fracture. CONCLUSION: Mandibular fractures are caused mainly by traffic ever since 1990, and rigid intrafixation is a satisfactory treatment which has been accepted by surgeons.

Accidents, Traffic↗

PubMed1999

[Internal fixation for zygomatic arch fracture with super-high molecular weight poly D, L-lactic acid mini-plates and screws: a study in dogs].

OBJECTIVE: To investigate the internal fixation effects of super high molecular weight (Mv = 6.0 x 10(5) kD) poly D, L-lactic acid(PDLLA) mini-plates and screws. METHODS: 10 dogs were utilized in this experiment with the self-contrast study method, comparing with the titanium mini-plates and screws. RESULTS: The mechanical properties of the PDLLA mini-plates and screws appeared to be sufficient to enable undisturbed healing of depressed zygomatic arch fracture. CONCLUSION: The good fixation effect of PDLLA mini-plates and screws was as same as that of the titanium mini-plates and screws without the need of secondary operation.

Animals↗

PubMed1999

[Tissue reaction and degradation of super-high molecular weight poly D, L-lactic acid mini-plates and screws: an animal experiment].

OBJECTIVE: To investigate the tissue reaction and degradation processes of the super-high molecular weight(Mv = 6.0 x 10(5) kD) poly D, L-lactic acid(PDLLA) mini-plates and screws through the internal fixation for zygomatic arch fracture. METHODS: It was carried out by the self-contrast study method and comparing with the titanium mini-plates and screws. RESULTS: There was no side-effects on bone healing. The reaction of soft and hard tissues to PDLLA mini-plates and screws was similar to that of the titanium mini-plates and screws. No complication had been seen with the use of PDLLA mini-plates and screws, including infection, foreign body reaction and underlying osteolysis. The PDLLA devices had no changes in shape after 3 months, and then became the grains in different sizes after 6 months, and were completely resorbed within 12 months in vivo. CONCLUSION: The super-high molecular weight PDLLA mini-plates and screws has good biocompatibility and proper degradation time. It is safe and effective to use the mini-plates and screws made of the super-high molecular weight PDLLA for internal fixation of bone.

Animals↗

PubMed1999

[A comparative study of mechanical properties of microwave-cured and conventional water bath-cured denture base resins].

OBJECTIVE: To study the mechanical properties of microwave-cured polymethyl methacrylate (PMMA) denture base resins. METHODS: Using experiment research, the mechanical properties of microwave-cured and water bath-cured PMMA materials were compared. RESULTS: The microwave-cured acrylic strips had equal or better mechanical properties than conventionally processed strips. CONCLUSION: The microwave-cured denture materials satisfies the requirements of the prosthetic clinic.

Biomechanical Phenomena↗

PubMed1999

[A primary study of relationship between proteolytic enzymes in dental plaque and deciduous caries].

OBJECTIVE: The purpose of this paper was to study the role of proteolytic enzymes in dental plaque in deciduous caries occurrence. METHODS: Fluorometry and spectrometry were used separately to determine the activities of leucine amino peptidase, dipeptidyl peptidase IV and trypsin-like proteinase in caries-positive and caries-free children. RESULTS: The activities of the three enzymes in dental plaque in different children were same (P > 0.05). CONCLUSION: The three enzymes may be not related to deciduous caries.

Child↗

PubMed1999

[The study of the activities of salivary proteolytic enzymes in children].

OBJECTIVE: The activities of proteolytic enzymes in saliva were assayed to determine whether they were related to caries sensitivity and gender in the children. METHODS: Fluorometric and photometric methods were applied. Three enzymes included leucine amino peptidase, dipeptidyl peptidase IV and trypsin-like proteinase. RESULTS: 1. Only dipeptidyl peptidase IV and trypsin-like proteinase were demonstrated in saliva, they were obviously lower than those in dental plaque (P < 0.05); 2. The activities of proteolytic enzymes of male and female children as well as caries-active and caries-free children showed no difference. CONCLUSION: Proteolytic enzymes play little role in caries formation of deciduous tooth.

Child↗

PubMed1999

[Cell proliferation and programmed cell death in tooth development].

OBJECTIVE: To evaluate the role of cell proliferation and programmed cell death (PCD) in the tooth development by detecting programmed cell death and expression of proliferating cell nuclear antigen (PCNA). METHODS: Expression of PCNA and PCD were detected by immunohistochemical staining and Tdt-mediated dUTP nick end labelling (TUNEL) in different stages of the tooth development of Sprague-Dawley rats. RESULTS: The positive cells of PCNA and PCD predominantly appeared at the proliferating growth center in the bud, the cap and the earlier bell stages of tooth development. PCNA and PCD were also observed in ameloblasts and odontoblasts, especially in the stellate reticulum cells of enamel organ and dental papilla during the period of dentin formation. CONCLUSION: Cell proliferation and programmed cell death are interrelated and interact on each other in the development of teeth, and they both involve in sculpturing the shape of teeth.

Animals↗

PubMed1999

[Surgical reduction and rigid internal fixation of midface fractures].

OBJECTIVE: To determine the cause, clinical characteristics and treatment of midface fractures. METHODS: A retrospective review of 98 patient records was conducted. Data regarding age, cause of fracture, anatomic site, treatment modalities and clinical results were reviewed. RESULTS: Of the 98 patients, 78.6% were male, with the peak incidence occurring in the age group from 21 to 40 years old. Of the fractures, 32.6% were due to traffic accidents, 24.5% to assaults, and 17.3% to accidental falls. Most patients (87.8%) were treated by open reduction surgery and rigid internal fixation. Only 12.2% of patients were treated by closed reduction fixation. Almost all of the patients regained normal face appearance and functional occlusion. CONCLUSION: Surgical reduction and rigid internal fixation of midface fractures is a satisfactory method of treatment.

Adolescent↗

PubMed1999

[Biocompatibility of self-designed absorbable hydroxyapatite/poly (DL-lactide) composites].

The biocompatibility of self-designed hydroxyapatite/poly (DL-lactide) rods was evaluated both in vitro and in vivo including Ames test, micronucleus test, acute and subacute systemic toxicity test, hemolysis test, hemopexis test and long-term muscle and bone implant test. The results indicate that the material has no toxicity, no stimulation and mutation, and it does not cause hemolysis and hemopexis. Consequently, the biocompatibility of the composite was good.

Absorbable Implants↗

PubMed1999

[Progress in technique of computer for three dimensional reconstruction from biological tissue series slices images].

The development of the technique of computer processing images and biotechnology from late 80's to early 90's has rovided the possibility of displaying three dimensional images of biological tissues truly. Now the technique of computer for three dimensional reconstruction is more and more widely used in the biological territory. This paper introduces the progress in the technique of computer for three dimensional reconstruction from biological tissue series slices images. Emphasis is laid on registration, reconstruction & display, image data compressing and image automatic segmentation.

Algorithms↗

PubMed1999

[The resolution of racemic sec-phenethyl alcohol on cellulose tribenzoate-based CSP: influence of different alcohols in the mobile phase].

Several primary and secondary alcohols (ethanol, 1-propanol, 2-propanol, 1-butanol) were used as the mobile phase components separately, to investigate their effects on the capacity factor and stereoselectivity of sec-phenethyl alcohol enantiomers on cellulose tribenzoate-based CSP. The chiral recognition mechanism for the enantiomeric aromatic alcohols studied may involve: (1) the aromatic portion of the solute may insert into a chiral cavity of the CSP through a hydrogen bonding interaction between the solute's alcoholic hydrogen and the ester carbonyl group on the CSP; (2) the mobile phase modifiers (various alcohols) compete with the solutes for chiral, as well as achiral, binding sites on the CSP; (3) the structure of the modifier has some effect on stereoselectivity through an alteration of the steric environment of the chiral cavity.

1-Butanol↗

PubMed1999

[Expression, purification and bio-activity analysis of oncostatin in GST-fusion expression system].

Oncostatin (OSM) is an important cytokine which has diverse biological activities. It may be useful in basic scientific and clinical studies. OSM was efficiently expressed by cloning the OSM gene into GST fusion expression vector. The level of expression of the fusion protein was about 50% of the total cell protein by SDS-PAGE analysis. The percentage of fusion protein in soluble protein could be 15% when the induction was in low temperature. The purity of purified GST-OSM with an affinity chromatography column was about 90% after the inclusion bodies had denatured and renatured. The result of activity study showed that the first two amino acids in N-terminal of the OSM were important to the biological activity of OSM.

Chromatography, Affinity↗