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Biomedical subjects

M Zhang

Publications and source records attributed to M Zhang.

At least 739 records · Page 41Linked to original sources
PubMed1997

Physician case-by-case assignment and participation in Medicare.

The prospect of budget cuts in Medicare is likely to result in less generous reimbursements from Medicare and thus affects physicians' willingness to accept Medicare patients with the reduced payments. This study examines physicians' decisions about case-by-case assignment and participation in Medicare in relation to Medicare reimbursement generosity. A two-part model is applied to a database from a national survey of physicians. The results indicate that reimbursement generosity from private insurance relative to that from Medicare negatively affects physicians' assignment rates, implying that the elderly's access to health care and/or the financial burden is likely to be jeopardized by further reductions in Medicare reimbursements.

Aged↗
PubMed1997

A quantitative assessment of osteoinductivity of human demineralized bone matrix.

Demineralized bone matrix (DBM) is widely used in the repair of pathologies associated with skeletal defects and periodontal diseases. The present study was directed at establishing in vivo and in vitro models for a quantitative assessment of the osteoinductivity of DBM before clinical use. Athymic mice were used in an in vivo assay to overcome the species limitations (for human DBM) found in xenogeneic animal models. Calcium contents of explants, as an indicator of new bone formation, were assayed and expressed as a change in the weight percent calcium in the explant as compared to the weight percent of calcium in the implanted material. A total of 82 mice (2 implants per mouse) were used in this study. Significant amounts of new bone were induced in this animal model in response to implantation of DBM. Muscular implantation was found to be more osteoinductive (increases of 10.0 +/- 0.4 calcium weight percent of explant) than subcutaneous implantation (increases of 1.62 +/- 0.27 calcium weight percent of explant) and new bone formation in muscular implantation sites of athymic mice mimics endochondral bone formation. Between weeks 1 to 4, the weight of explanted materials did not significantly differ from the weight of the implanted material; however, by week 5 the explant weight began to increase. Calcium deposition over the 5 weeks of implantation increased in a nearly linear fashion. Consequently week 4 was chosen as the optimum time for explantation in the in vivo assay in that sufficient calcium levels had been achieved without a significant increase in explant dry weight. Aliquots of 10, 20, 30, and 40 mg per implantation site were used in dose response studies in the in vivo bioassay. Dose response curves with DBM exhibited maximal activity at the 20 mg DBM implant dose in the in vivo bioassay. An in vitro bioassay was also developed where human periosteal (HPO) cells were chosen because osteoprogenitor cells found in bone repair typically come from periosteal tissue. Alkaline phosphatase (ALP) activity in confluent cell cultures of HPO cells exposed to DBM, as an indicator of osteoblast induction, reached its highest level on day 5 of DBM treatment. Aliquots of 2, 5, 10, 20, 30, and 40 mg DBM per flask were chosen in dose response studies using the in vitro bioassay. These dose response studies with DBM revealed that quantities approximating 5 to 10 mg DBM in the in vitro model provided for maximal levels of ALP in cell extracts. A linear correlation (R2 = 0.7397) was demonstrated between the in vivo calcium remineralization assay and the in vitro ALP assay of osteoinductivity of DBM, suggesting that the in vitro assay can be used to quantitatively assess the osteoinductive potential of DBM where production and distribution of clinically usable DBM dictates rapid analysis.

Adult↗
PubMed1997

Effect(s) of the demineralization process on the osteoinductivity of demineralized bone matrix.

The relationships between residual calcium levels and particle size of ground demineralized bone matrix and its osteoinductive potential were investigated using in vitro and in vivo assays. The effects of variable residual calcium levels, variable particle sizes, and donor age and gender were studied using a tissue culture-based bioassay (in vitro) as well as an athymic mouse (in vivo) bioassay. The osteoinductive potential of the bone-derived biomaterial was assessed by measuring the degree of new bone formation (change in percent calcium content after 4 weeks of implantation) in the in vivo assay and levels of alkaline phosphatase activity associated with cultures of human periosteal cells (HPO cells) in the in vitro assay, respectively. Slightly demineralized bone matrix and overly demineralized bone matrix possessed a degree of osteoinductive potential whereas bone demineralized to levels of approximately 2% residual calcium provided for maximum osteoinductive potential in both assay systems. The osteoinductive potential of ground demineralized bone varied relative to the particle size such that DBM particles ranging from 500 to 710 microns provided for the highest level of calcium deposition (increase of 8.1 weight percent calcium) after 4 weeks of implantation in muscle pouches of an athymic mouse, whereas explanted particles less than 250 microns showed the lowest level of calcium deposition (increase of only 2.8 weight percent calcium). In the donor age and gender study, DBM from different donors were divided into 5 age groups for both female and male donor derived bone: less than 20, 21 to 30, 31 to 40, 41 to 50, and 51 to 60 year old age groups. This study indicated that DBM from female donors in the 31 to 40 years old age group and male donors in the 41 to 50 year age group possess the highest osteoinductive potential, whereas DBM derived from donor bone from both female and male donors in the 51 to 60 year age group presented the lowest osteoinductive potential. DBM derived from male and female donors did not in general show significant differences in osteoinductive potential.

Adult↗
PubMed1997

[Severe combined immunodefficiency disease, 4 autopsy case reports].

OBJECTIVE: To study the pathological changes of severe combined immunodefficiency disease (SCID). METHODS: 4 cases with SCID proven by autopsy examination. RESULTS: All patients were male with an average age of 5 moths. The major clinical manifestations included severe repeated infection with bacteria, virus, fungi and pneumocystis carinii. Autopsy examination revealed hypoplasia of thymus, spleen and lymph nodes. 1 case died from pneumocystis carinii pneumonia and BCG vaccine disease, 2 cases died of severe general infection and 1 case died from large cell lymphoma. CONCLUSIONS: The main diagnosis criteria for SCID are hypoplasia of both T and B lymphocytes, the pathologic changes of SCID are very complex.

Cytomegalovirus Infections↗
PubMed1997

Tumor necrosis factor mediated release of platelet-derived growth factor from bovine cerebral microvascular endothelial cells.

AIM: To study the effect of tumor necrosis factor (TNF) on platelet-derived growth factor (PDGF) release from bovine cerebral microvascular endothelial cells (BCMEC), and the protection of drugs on proliferation of bovine cerebral microvascular smooth muscle cells (BCMSMC). METHODS: BCMEC and BCMSMC were cultured in vitro. Effects of TNF on PDGF release from BCMEC were investigated by crystal violet assay. RESULTS: TNF did not promote the proliferation of BCMSMC directly. But the postculture medium of BCMEC stimulated by TNF promoted the proliferation of BCMSMC in a concentration (5-20 micrograms.L-1)-dependent manner, and the mitogenic activity was neutralized by antibody to PDGF. The BCMSMC proliferation was increased 34 +/- 4% over control by TNF (20 micrograms.L-1). Imperatorin (Imp), iso-imperatorin (iso-Imp), and 6-(alpha, alpha-phenylacetylpiperazinyl) phenyl-5-methyl-4, 5-dihydro-3 (2H)-pyridazinone (PMDP) 1-100 mumol.L-1 did not affect the PDGF release from BCMEC stimulated by TNF, but inhibited the BCMSMC proliferation promoted by PDGF concentration-dependently. CONCLUSION: TNF promoted PDGF release from BCMEC. The proliferation of BCMSMC stimulated by TNF must be mediated by growth factor, such as PDGF. Imp, iso-Imp, PMDP inhibited proliferation of BCMSMC stimulated by PDGF.

Animals↗
PubMed1997

[Laser transnasal dacryocystorhinostomy under head mirror].

Laser transnasal dacryocystorhinostomy under head mirror is a new approach for surgical treatment of chronic lacrimal obstruction. This technique has several advantages, such as less damage, less operative complications and so on. This paper presented the results of 37 cases who had undergone transnasal dacryocystorhinostomy for chronic dacryocystitis under head mirror. The postoperative follow-up time was 3-24 months. The effective rate was 95.6%. The operative technique was also discussed in this paper.

Adolescent↗
PubMed1997

[Hodgkin's disease with concurrent infection of toxoplasmosis].

Hodgkin's disease (HD) is a specific type of malignant lymphoma characteristic of local and general lymphadenectasis. Aquired toxoplasmosis (AT) is one kind of lymphoadenopathy without fever and fatigue. When the two diseases coexist, clinical and pathological misdiagnosis may be made. This is the first male case of toxoplasmosis and Hodgkin's disease in China, diagnosed by surgical removal of the major part of the cervical and supraclavicular masses, detection of blood anti-toxoplasma gondii antibody, PCR analysis of toxoplasma gondii DNA, and pathological, ultrastructural and immunohistochemical studies of the tumour tissues. The patient treated by radiation and chemotherapy was abated.

Adult↗
PubMed1997

[The application of computer imaging simulation in nose augmentation].

By measurement and analysis, the postoperative image was simulated in standard facial image of the saddle nose using computer imaging and the software developed by us. When the simulated image is accepted by both the surgeon and the patient, the computer gives data to instruct the operation. The authors described how to obtain the standard facial image and how to reduce error. The computer imaging simulation makes the cosmetic operation accurate, quantitative and imaged, and its applications will be broadened.

Adult↗
PubMed1997

[Invasive infection and multiple organ dysfunction syndrome (MODS) in burns].

The article analysed the relationship between invasive infection and MODS in 158 burned cases. The characteristics in MODS following invasive infection are presented. 1. Morbidity of MODS is high, it reaches 81.6%. 2. MODS may become progressive MOF, the possibility is 50%. 3. Death is associated with MOF, rather than by MODS. Mortality of MOF is very high, it is over 90%. Among various microbes it is Pseudomonas pyocyanea that causes highest morbidity of MODS. The mechanism of MODS is complex and not fully understood. The treatment of MODS is difficult, so it is essential to control invasive infection. In case of severe infection, protection of each organ is very important in order to avoid organ dysfunction progressing to organ failure.

Adolescent↗
PubMed1997

[Characterication of reference strains of L. interrogans in China by ISSP-PCR].

The gene polymorphism of the DNAs extracted from reference strains of L. interrogans in China was characterized by LSSP-PCR primered by G1 or G2, which were a pair of specific primers for L. interrogans. The fingerprinting produced by LSSP-PCR showed that serovar lai, serovar canicola, serovar pyrogens, serovar autumnalis, serovar australis, serovar linhai, serovar wolffi and serovar haemolytic have similar patterns, but serovar hebdomadis, serovar javanica, serovar ballum, serovar pomona, serovar spaidjin, serovar tarassov and serovar manahao I have different profiles. This result agreed with the classification of genetic species by Yasuda. The utilization of LSSP-PCR banding patterns in the identification of leptospries in blood samples also gained encouraging results. Compared with the routine methods in genetic species classification, LSSP-PCR has the advantages of rapidity, simplicity and low-cost. It appears to be a promising tool in studying such slowly growing bacteria as leptospires. Further exploration of LSSP-PCR in classification and identification of Leptospires is worthwhile.

DNA, Bacterial↗
PubMed1997

[Analysis on speciems of serum and urine in 66 cases of early leptospirosis by PCR and biotin-AMPPD hybridization].

We used polymerase chain reaction (PCR) and Biotin-AMPPD hybridization to detect leptospiral DNA in blood and urine samples in 66 patients at the early stage of leptospirosis. The results showed that PCR and Biotin-AMPPD hybridization not only ruled out the non-specific PCR amplification and increased the reliability for clinical specineus of leptospirosis but also raised the detecting sensibility (from 71.3% to 86.1%). The positive rates of PCR resulted from serum and urine showed no statistical difference; therefore urine sample is worthy of application and dissemination for detecting leptospires at the early stage of leptospirosis. Urine sample is easier for one to collect, preserve and has less intervention. The primers G1, G2 are optimal opplication of PCR in epdemic areas in China.

Biotin↗
PubMed1997

[Isolation of the expression fragments with the probe pool of human chromosome 14 q 24.3 generated by microdissection].

The strategy of isolating the band-specific expression fragments from the probe pool of human chromosome generated by microdissection was reported in present paper. A chromosome 14 q 24.3 band-specific single copy DNA library was constructed based on this probe pool. Using this pool DNA as probe to hybridize the human bone marrow cell cDNA library, 68 primary positive clones were selected from 5 x 10(5) cDNA clones. Of them 32 clones were got in second-round screening and designed as cFD 14-1-32. Finally, 24 bandspecific expression fragments were identified from these 32 positive clones by analysing the results of DNA hybridization. Those band-specific clones can hybridize to both 14 q 24.3 DNA and human genomic DNA, but have no hybridization signal with 17 q 11-12 DNA. Partial sequences of 13 fragments of them were sequenced and were identified as novel cDNA sequences as well as have some homology with known genes in NCBI database. Analysis of expression spectrum of cFD 14-1 suggested that the cDNA fragments thus obtained can be used to isolate the genes not yet be cloned in 14 q 24.3 region.

Base Sequence↗
PubMed1997

Two novel mutations in phenylalanine hydroxylase gene and in vitro expression analysis on mutation Arg252Gln.

We report novel mutations in exon 7 of human phenylalanine hydroxylase (PAH) gene of phenylketonuria (PKU) in southern Chinese, analysed by using PCR-DGGE (denaturing gradient gel electrophoresis), solid phase DNA sequencing and in vitro expression. One of the 2 novel mutations, IVS6nt-1, is an intron-exon junctional mutation which results a splicing defect in mRNA. Arg252Gln is another novel mutation with residual PAH activity only 24% compared to wild type in in vitro mutagenesis and expression in Cos-1 cell. Other 3 known mutations and polymorphism including Arg241Cys, Arg243Gln and Val245Val (GTG to GTA) together with these novel mutations composed the mutational profile of exon 7 in the PAH gene of PKUs in this populations.

Exons↗
PubMed1997

[Pharmacological effect of cortex Magnoliae officinalis on digestion system].

Experiments have shown that the ethanol extract of Cortex Magnoliae Officinalis 5 g/kg, 15 g/kg may significantly inhibit HCl-induced gastric ulcer in mice as well as Cassia angustifolia Leaf-induced experimental diarrhea in mice. 3 g/kg and 10 g/kg have a marked choleretic effect on rats. These results show that Cortex Magnoliae Officinalis helps improve the condition of digestion.

Animals↗
PubMed1997

[The experimental observation on characteristics of soft tissues infection in maxillofacial region wounded by high velocity missile].

In this experimental study, maxillofacial regions of dogs were wounded by steel spheres, which weight 1.03 g at a mean primary velocity of 1500 m/s. Aerobe and anaerobe bacteria in the muscles of different interval from wound track edge were cultured at different time after wound. The results showed that there was bacteria infection in the soft tissues between 0 and 0.5 cm from wound track edge in 6 hours after wound. The quantity of bacteria obviously increased following time prolonging, on the contrary, it was much lower than threshold value of bacteria infection within 24 hours. The experimental results suggested that there was obvious bacteria infection in the soft tissues within 0.5 cm distance from wound track edge in maxillofacial firearm wound region. During the debridement removing soft tissues within 0.5 cm distance from wound track edge, the infection of wound region could be controlled. Using effective antibiotics is an important measure of controlling infection of wound after debridement.

Animals↗
PubMed1997

[Applications of computer image processing and graph processing technologies in digital modelling of 3-D shapes of teeth, jaw and prosthesis].

In this paper, the images of sliced sections or CT sections of the specimen of teeth, jaw and prosthesis were processed by a computer image analysing system, and the plane shape of the 3-D objects of interest on the sections was converted into digital images using a special software module for contour analysing. Then the images were adjusted in scale, modified in coordinates and smoothed in shape, and the data format was transferred for finite-element analysis by a specially designed software. In such ways a method for the digital modelling of the 3-D shape of teeth, jaw and prosthesis was successfully established.

Computer Simulation↗