Biomedical subjects

J Xu

Publications and source records attributed to J Xu.

At least 847 records · Page 47Linked to original sources

PubMed1997

[Experimental study on supraeruption of the unopposed miniature pig molars].

Supraeruption of the molars in the absence of antagonist molars or without occlusal contacts was observed in a miniature pig. Tetracycline was used to label the new regenerated cementum and alveolar bone associated with the supraeruption. The results showed that the molar through root canal treatment migrated the same level as the molars with pulp, which means that the hydrodynamic and hydrostatic forces arising from the blood in pulp vessels look doubtful. Cementum and alveolar bone deposition was seen around the apical, cervical regions and under the furcation area. The thickness of the deposition layers was almost the same as the supraerupted volume from the model measurement.

Animals↗

PubMed1997

[Pediatric ocular trauma: a retrospective survey].

PURPOSE: To determine the risk factors for pediatric ocular injuries, especially those resulting in severe visual impairment, and to identify the trends and preventable causes. METHODS: A retrospective survey was conducted for all pediatric trauma cases at Zhongshan Ophthalmic Center from January 1989 through December 1992. Four hundred eighty-seven cases of 15 years old or younger were recruited in this study. Stepwise regression analysis was used to identify the relations between the visual prognosis and the potential risk factors (age, gender, time after injury, type of injury, and cause of injury) RESULTS: The male to female ratio was approximately 3:1, and most were 4 to 8 years old. Non--perforating trauma in the anterior segment was the most common type of injury. The final recorded best corrected visual acuity was 0.3 or better in 65% of the patients, while 19% were found to be 0.05 or worse with best correction. The following formula was generated by multiple linear regression model: Visual outcome = 0.963775 - 0.0896543 x (type of injury). CONCLUSION: Pediatric ocular trauma may cause severe visual impairment and occurs most frequently at the age of 4 to 8 years. The visual outcome is mainly associated with the type of injury.

Adolescent↗

PubMed1997

En bloc transplation of kidney and whole pancreas with a segment of duodenum in rats.

For meeting the clinic needs in simultaneous pancreas and kidney transplantation (SPK), we successfully establish a syngeneic SPK transplatation model in Lewis rats. The results indicate that this model is feasible with a 82.6% successful rate of operation and a 69.6% survival rate in the first postoperative week. In long-term survived rats, the blood supplies are well established, function of the grafts (pancreas and kidney) maintains normal. This model is suitable for theoretical research in SPK transplantation for its reasonable physiology with pancreatic juice drained into intestine and reduced postoperative complications in urinary tract and carbohydrate metabolism.

Animals↗

PubMed1997

[The methods of mean scatterer spacing estimation and its application].

Ultrasonic Backscattered Signal(UBSS) from tissues is fundamentally a statistical signal. The statistics of UBSS provide information relating to the number, mean spacing and the scattering cross sections of the scatterers constituting the tissue. Mean scatterer spacing(MSS) is an important parameter for describing the biological tissues microstructural features and tissues ultrasonic scattering characteristics. This paper reviews the methods of MSS estimation as well as ultrasonic imaging based on the scatterer spacing.

Anthropometry↗

PubMed1997

[Early observation of healing of rabbit mandibular defects with porous blocks consisting of polylactic acid and recombinant human bone morphogenetic protein-2].

The effects of bone morphogenetic protein (BMP) which can induce bone formation have been surely proved, Porous polylactic-acid blocks were prepared by a freeze-drying method. During preparation of the blocks, recombinant human bone morphogenetic protein-2(rhBMP-2) was mixed with the polylactic-acid(4 mg per block). PLA-rhBMP-2 was implanted in the mandibular defects of rabbit and retrieved after 2 or 4 weeks. The results showed that: with the PLA-rhBMP-2 blocks, new bone formation was observed in 2 weeks after implantation, and plain PLA blocks produced a little of new bone formation in the edges of defect even in 4 weeks after implantation. Calcium content of the retrieved PLA-rhBMP-2 block was statistically higher than that of plain PLA blocks. These results suggest that PLA may be effective delivery system for BMP and the PLA/rhBMP-2 block may potentially have usefulness as a bone graft substitute.

Animals↗

PubMed1997

[Determination on the electric-mate order of prosthodontic materials in artificial saliva].

Electric-mate corrosion of the different prosthodontic materials has been noticed in oral cavity. The aim of this investigation was to determine corrosion potential of prosthodontic materials, and to acquire the electric-mate order in artificial saliva. That will conduct us to select the materials of resistance corrosion. For resistance electric-mate corrosion, it's better to use same materials, or to use close materials of the electric-mate order.

Chromium Alloys↗

PubMed1997

[Clonning and sequencing of partial gene of hepatitis G virus (HGV) from Nanjing of China].

Partial gene of hepatitis G virus (HGV) was cloned and sequenced from the serum of a patient with post-transfusion hepatitis C in Nanjing of China by reverse transcription-polymerase chain reaction (RT-PCR). The sequence showed 89.09%, 92.12%, 87.27%, 93.94% nucleotide identity over the corresponding region of HGU44402, HGU45966, HGU36380 in America and HGV isolate in Hebei Province of China respectively. Forty patients with post-transfusion hepatitis C and thirty patients with hepatitis non A-E were detected for HGV RNA by RT-PCR, the HGV RNA positive rate were 10.00% and 6.67% respectively.

Base Sequence↗

PubMed1997

[Cloning and expression of heavy- and light-chain variable region genes of monoclonal antibody specific for human fibrin].

OBJECTIVE: To obtain the minimum molecule having activity to bind human fibrin. METHODS: The immunoglobulin heavy- and light-chain variable region (VH and Vkappa) genes were isolated from 8E5 hybridoma cells, which secreted a monoclonal antibody against human fibrin, by RT-PCR. An expression vector pOPE51-8E5 was constructed for the recombinant VH-Vkappa expression. The transformed E. coli JM 109 cells were propagated and induced by IPTG. RESULTS AND CONCLUSION: Expression product was found in the periplasmic space and inclusion bodies by SDS-PAGE and immunobloting. It was a 30000 single chain fragment (scFv) with antigen-binding specificity. The yield of the scFv was 28.9% of the total bacterial proteins.

Animals↗

PubMed1997

[Risk of leukemia among diagnostic x-ray workers in China between 1950 and 1990].

OBJECTIVE: To explore the relationship between radiation and leukemia. METHODS: Leukemia incidences (1950-1990) in 27011 diagnostic X-ray workers and in 25782 other medical specialists employed between 1950 and 1980 in China were compared. RESULTS: The relative risk (RR) of leukemia in the diagnostic X-ray workers was 2.25-fold (95% C1=1.59-3.09, P<0.001) higher than that in the control group. The average age of the emergence of leukemia was 10.4 years younger in X-ray workers than in control group. The peak incidence of leukemia in X-ray workers occurred 10-14 years after engaging in X-ray work. The highest RR of leukemia was found in those who were engaged in X-ray work before 1965 or at age under 20 years. CONCLUSION: Incidence of Leukemia in X-ray workers increased and it was correlated with radiation dosage and duration.

Adult↗

PubMed1997

[Determinaion of artificial synthetic pigment in the drug by reflection spectrophotometry].

Solid phase spectrophotometry is a new, simple, fast and sensitive trace analytical method. In this report, it is presented a method that the polyamide was used for the absorbence and the reflectances absorbances were measured directly with remodelled the colorimetric cell. Not only the trace inorganic ion can be analysed by the solid phase method, but also the artificial synthetic pigment in the drug can be determined, the results are satisfied.

Coloring Agents↗

PubMed1997

The interaction of tumour necrosis factor alpha and endothelin-1 in pathogenetic models of asthma.

BACKGROUND: There is evidence that tumour necrosis factor alpha (TNF alpha) may be an important mediator in initiating asthmatic airway inflammation. It has been proposed that endothelin-1 (ET-1) is involved in bronchoconstriction and airway remodelling in asthma. It is not known, however, if there is any interaction between TNF alpha and ET in perpetuating airway inflammation in asthma. OBJECTIVE: The present study aimed to determine the activities of ET-1 and TNF alpha in ovalbumin-sensitized guinea pigs and their roles in the development of airway inflammation. METHOD: Twelve guinea pigs were sensitized by ovalbumin injection and aerosol inhalation. ET-1 levels were measured in both bronchoalveolar lavage fluid (BALF) and plasma by 125-labelled endothelin-1 (ET-1) radioimmunoassay. The TNF alpha activity released from alveolar macrophage (AM) in BALF was estimated by ELISA. Cultured bovine airway smooth muscle cells (BASMCs) were treated with TNF alpha (1000 units/5 x 10(4) cells) for different times. ET-1 levels in harvested medium from these cells were measured by radioimmunoassay. Cultured human fetal lung fibroblasts (HFLFs) were incubated with ET-1 (10(-8) approximately 10(-6)M), then 3HTdR incorporation to these cells and cell counting were performed. The effects of ET-1 stimulation on the granulocyte macrophage colony stimulating factor (GM-CSF) gene expression in HFLFs were estimated by using RT-PCR method. RESULTS: ET-1 levels in both plasma and BALF were significantly higher in ovalbumin-sensitized guinea-pigs compared with those in controls (422.27 +/- 175.0 pg/mL vs 277.311 +/- 88.0 pg/mL, P < 0.05, 81.22 +/- 16.15 vs 49.81 +/- 12.64 pg/mL, P < 0.05) while TNF alpha activity was also significantly increased in the OVA-sensitized group compared with that in the control group (6010 +/- 1900 pg/mL vs 2810 +/- 450 pg/mL, P < 0.05). The ET-1 level in harvested medium of BASMCs rose significantly in 12 h in the TNF-alpha treated group (from < 5 pg/mL to 53.72 +/- 14.3 pg/mL, P < 0.001), and remained at a similar level for 24 h in the TNF alpha treated group. It was shown that ET-1 not only stimulated cell proliferation but also induced GM-CSF mRNA expression in HFLFs. CONCLUSION: ET-1 levels in both plasma and BALF and TNF alpha release from macrophage are increased significantly in ovalbumin-sensitized guinea-pigs. TNF alpha stimulates ET-1 secretion from cultured BASMCsw; ET-1 accelerates cell proliferation and induces GM-CSF mRNA expression in the human fetal lung fibroblast.

Administration, Inhalation↗

PubMed1997

II. Localization and characterization of dopamine D4 binding sites in rat and human brain by use of the novel, D4 receptor-selective ligand [3H]NGD 94-1.

The dopamine D4 selective ligand, [H]NGD 94-1, was used in these studies to characterize binding sites in rat and human brain tissue by membrane binding and autoradiography techniques. Autoradiographic analysis of rat brain showed that specific [3H]NGD 94-1 binding was greatest in entorhinal cortex, lateral septal nucleus, hippocampus and the medial preoptic area of the hypothalamus. This nonstriatal distribution of [3H]NGD 94-1 binding was distinct from the autoradiographic distribution of dopamine D2 and D3 receptor subtypes. In homogenate preparations from rat brain regions, [3H]NGD 94-1 binding sites were low in density (<30.0 fmol/mg protein). The low density of D4 binding sites was corroborated by autoradiographic comparisons in which binding density for D4 receptors as measured by [3H]NGD 94-1 was only 1/7 of D2 and 1/5 of D3 receptor densities, despite corrections for differing radioligand binding characteristics. Pharmacological evaluation showed high affinity at rat [3H]NGD 94-1 binding sites for compounds with known D4 receptor affinity and little displacement by compounds with affinity for dopamine D1/D2/D3 receptor subtypes. Specific, high-affinity [3H]NGD 94-1 binding was also present in several human brain regions, including hippocampus, hypothalamus, dorsal medial thalamus, entorhinal cortex, prefrontal cortex and lateral septal nucleus. High-affinity [3H]NGD 94-1 binding was not present in any human striatal region examined. The pharmacological profile of [3H]NGD 94-1 binding sites in human brain was consistent with that previously demonstrated for cloned human D4 receptors expressed in mammalian cells. These findings suggest that specific, high-affinity [3H]NGD 94-1 binding exists in rat and human brain and that these sites reflect populations of dopamine D4 receptors with a distribution unique among dopamine receptor subtypes.

Animals↗

PubMed1997

Study of mathematical model for product formation with recombinant microbes expressed IFN.

Based on the known molecular interactions of aporepressor, corepressor, and inducer, a mathematical model of product formation about the Trp operon regulated recombinant microbes has been proposed. The linear relation of the overall transcription rate constant and overall translation rate constant on the specific growth rate has been suggested. We used experimental data where engineered microorganisms express interferon (IFN). Decay constant of IFN, mRNA transcription rate constant, and IFN expression rate constant have been estimated. An equation related to IFN concentration in fermentation on specific growth rate and Trp concentration has been obtained. By application of the equation, the expression of IFN is calculated based on Trp concentration and specific growth rate in fermentation. Also, the optimum overall culture time can be determined.

Escherichia coli↗

PubMed1997

Polyethylene glycol400 laurate synthesized by immobilized lipase in a solvent-free system.

Conditions for the esterification of polyethylene glycol400 (PEG400) with lauric acid by immobilized lipase from Candida sp. 1619 in a solvent-free system were investigated. The esterification degree was increased greatly through the dehydration that occurred during the reaction. When the amount of lauric acid added exceeded the stoichiometric amount the yield of product was further improved by fed-batch feeding of PEG400. In the reaction system that was composed of 5.0 mmol of lauric acid, 2.5 mmol of PEG400, 20 mg of immobilized lipase (200 u), 0.2 ml of water, at 40 degrees C shaken for 48 h in a 100-ml conical flask without a plug, the esterification degree of 98.9% was reached. When the amount of lauric acid used was increased to 60 mmol, the PEG400 in reaction system was completely esterified. The recovery yield of product was 95% by hexane extraction and the product was identified as diester by means of TLC.

Candida↗

PubMed1997

Border malaria in Yunnan, China.

Yunnan Province, due its international borders with Myanmar, Vietnam and Lao PDR has a large number of imported cases of malaria, including a high proportion of Plasmodium falciparum, as a result of the mobility of the population. This movement is due to workers coming from other provinces where there is no malaria to work in the productive tropical lowlands. Chinese nationals who have gone to work in neighboring countries, border trade and refugees from Myanmar. Much of Yunnan is peopled by ethnic minorities living in remote mountainous and forested areas which are difficult to reach. However, surveillance has been strengthened by training 3,900 primary health care workers and combining the search for visiting foreigners, returning Chinese and people from other provinces with public security, customs formalities and employers. Any visitor detected by these services is obliged to have a blood slide taken. This has resulted in an earlier and more complete detection of malaria cases, reducing incidence from 19.19 to 12.12/10,000 in the border area over the last 10 years. This is despite a considerable increase in population movement and the threat of drug resistant malaria.

China↗

PubMed1997

[Polymorphism of group specific component (Gc) in nine Han subpopulations in China].

Isoelectric focusing (IEF) followed by immunofixation in thin layer polyacrylamide gels (pH4-6) was used to analyse the Gc subtypes of 1841 individuals from nine Han geographically distributed populations in China. The Gc1F gene frequencies in these Han subpopulations from Lanzhou, Huhhot, Harbin, Xi'an, Zhengzhou, Chengdu, Guiyang, Zhangzhou and Harras in Guangdong Province were 0.3905, 0.4333, 0.4193, 0.4146, 0.4182, 0.4035, 0.4045, 0.4381 and 0.4347 respectively; Gc1S were 0.3071, 0.2190, 0.2734, 0.2261, 0.2182, 0.2871, 0.2889, 0.2738 and 0.2764 respectively; Gc2 were 0.2786, 0.3357, 0.2917, 0.3367, 0.3295, 0.2896, 0.3065, 0.2667, and 0.2814 respectively. GcV were 0.0238, 0.0119, 0.0156, 0.0226, 0.0341, 0.0198, 0.0000, 0.0214 and 0.0075 respectively. The results of present study indicated a clear cline of linear change from north to south China in allelic frequency at the Group-Specific Component (Gc) locus among nine Chinese populations. Three alleles, Gc1F, Gc2 and GcV, showed frequencies varying from 0.3905 to 0.4381, from 0.2786 to 0.3367 and from nil to 0.0341, respectively, over these geographical subpopulations. In addition, some rare variant phenotypes of Gc in Chinese populations were discussed.

China↗

PubMed1997

TGF-beta 3 inhibits the increased gene expressions of pulmonary surfactant proteins induced by dexamethasone in fetal rat lung in vitro.

OBJECTIVE: To determine the effects of transforming growth factor-beta 3 (TGF-beta 3) on expressions of surfactant proteins (SPs). METHODS: Northern blot hybridization and reverse transcriptase polymerase chain reaction (RT-PCR) were employed to determine the SP-A, SP-B and SP-C mRNA levels of cultured lung explants and type II cells from fetal rat lungs. RESULTS: TGF-beta 3 alone did not affect the expressions of SPs either in explants or in type II cells. However, TGF-beta 3 did inhibit the increase of SP-B, SP-C mRNA levels caused by dexamethasone (100 nmol/L), in a dose-dependent manner. Furthermore, TGF-beta 3 had no direct inhibition on the increase of SP-B, SP-C mRNA induced by dexamethasone in type II cells, but had an indirect inhibitory effect mediated by fibroblasts. CONCLUSION: TGF-beta 3 plays an important inhibitory role in the development of pulmonary surfactant proteins. The present study may provide a possible explanation for the unideal effect of glucocorticoids in the prevention of neonatal respiratory distress syndrome.

Animals↗

PubMed1997

[Comparison of two techniques used in immediate postplacental insertion of TCu 380A intrauterine device: 12 month follow-up of 910 cases].

OBJECTIVE: To compare the efficacy of hand-insertion and ring forceps-insertion of TCu 380A intrauterine device (IUD) in immediate postplacental insertion (IPPI). METHODS: 910 vaginal delivery women in Shanghai received a TCu 380A IUD inserted within 10 minutes after delivery of the placenta. Among them, 97.7% were primipara. The women were randomly divided into two groups: 470 cases in hand-insertion group and 440 in ring forceps-insertion group. Using life-tale method and X2 test, we compared the expulsion rates and other causes of removal after follow-up for 12 months in the two groups. RESULTS: The follow-up rate at 6 and 12 months were 95.16% and 92.64%, respectively. No uterine perforation and infection occurred in the 910 cases, and only one pregnancy in the hand-insertion group. Expulsions were the main reason for discontinuation. The 12-month gross cumulative expulsion rates were 15.86 and 15.88 per 100 women in the hand-insertion group and ring forceps-insertion group, respectively, and the removal rates due to bleeding and (or) pain were 2.11 and 1.57, respectively. No difference was statistically significant (P > 0.05). CONCLUSION: The two different insertion techniques do not significantly affect discontinuation rates in vaginal IPPI using the TCu 38)A IUD; the TCu 380A IUD appears to be suitable for postpartum insertion in Chinese women.

Adult↗