Search PubMed⌕ Search

Biomedical subjects

J Tian

Publications and source records attributed to J Tian.

At least 127 records · Page 7Linked to original sources
PubMed1997

Gamete interactions in Xenopus laevis: identification of sperm binding glycoproteins in the egg vitelline envelope.

A quantitative assay was developed to study the interaction of Xenopus laevis sperm and eggs. Using this assay it was found that sperm bound in approximately equal numbers to the surface of both hemispheres of the unfertilized egg, but not to the surface of the fertilized egg. To understand the molecular basis of sperm binding to the egg vitelline envelope (VE), a competition assay was used and it was found that solubilized total VE proteins inhibited sperm-egg binding in a concentration-dependent manner. Individual VE proteins were then isolated and tested for their ability to inhibit sperm binding. Of the seven proteins in the VE, two related glycoproteins, gp69 and gp64, inhibited sperm-egg binding. Polyclonal antibody was prepared that specifically recognized gp69 and gp64. This gp69/64 specific antibody bound to the VE surface and blocked sperm binding, as well as fertilization. Moreover, agarose beads coated with gp69/64 showed high sperm binding activity, while beads coated with other VE proteins bound few sperm. Treatment of unfertilized eggs with crude collagenase resulted in proteolytic modification of only the gp69/64 components of the VE, and this modification abolished sperm-egg binding. Small glycopeptides generated by Pronase digestion of gp69/64 also inhibited sperm-egg binding and this inhibition was abolished by treatment of the glycopeptides with periodate. Based on these observations, we conclude that the gp69/64 glycoproteins in the egg vitelline envelope mediate sperm-egg binding, an initial step in Xenopus fertilization, and that the oligosaccharide chains of these glycoproteins may play a critical role in this process.

Amidohydrolases↗
PubMed1997

Pax-5 is identical to EBB-1/KLP and binds to the VpreB and lambda5 promoters as well as the KI and KII sites upstream of the Jkappa genes.

During B cell differentiation, the pre-B cell stage plays a significant role in immunoglobulin gene rearrangement in the context of the allelic exclusion and kappa chain gene rearrangement. We previously reported that the early B cell-specific binding protein (EBB)-1 transcription factor binds to the promoters of two pre-B cell-specific genes, VpreB and lambda5, and regulates their pre-B cell-specific expression. Here, we demonstrate that EBB-1 binds to the KI and KII sites in the upstream of Jkappa region, which are crucial for kappa chain gene rearrangement. Gene transfer and gel-shift assays demonstrate that EBB-1 is identical to Pax-5 and binds to promoters of VpreB and lambda5 as well as the KI and KII sites. Our results suggest that Pax-5 plays an important role in the coordinate regulation of several immunoglobulin gene family members that are crucial in B cell development.

Animals↗
PubMed1997

Latency estimation of auditory brainstem response by neural networks.

In the clinical application of auditory brainstem responses (ABRs), the latencies of five to seven main peaks are extremely important parameters for diagnosis. In practice, the latencies have mainly been done by manual measurement so far. In recent years, some new techniques have been developed involving automatic computer recognition. Computer recognition is difficult, however, since some peaks are complicated and vary a lot individually. In this paper, we introduce an artificial neural network method for ABR research. The detection of ABR is performed by using artificial neural networks. A proper bandpass filter is designed for peak extraction. Moreover, a new approach to estimate the latencies of the peaks by artificial neural networks is presented. The neural networks are studied in relation to the selection of model, number of layers and number of neurons in each hidden layer. Experimental results are described showing that artificial neural networks are a promising method in the study of ABR.

Evoked Potentials, Auditory, Brain Stem↗
PubMed1997

Targetting of the gene encoding fibrillin-1 recapitulates the vascular aspect of Marfan syndrome.

Aortic aneurysm and dissection account for about 2% of all deaths in industrialized countries; they are also components of several genetic diseases, including Marfan syndrome (MFS). The vascular phenotype of MFS results from mutations in fibrillin-1 (FBN1), the major constituent of extracellular microfibrils. Microfibrils, either associated with or devoid of elastin, give rise to a variety of extracellular networks in elastic and non-elastic tissues. It is believed that microfibrils regulate elastic fibre formation by guiding tropo-elastin deposition during embryogenesis and early post-natal life. Hence, vascular disease in MFS is thought to result when FBN1 mutations preclude elastic fibre maturation by disrupting microfibrillar assembly. Here we report a gene-targetting experiment in mice that indicates that fibrillin-1 microfibrils are predominantly engaged in tissue homeostasis rather than elastic matrix assembly. This finding, in turn, suggests that aortic dilation is due primarily to the failure by the microfibrillar array of the adventitia to sustain physiological haemodynamic stress, and that disruption of the elastic network of the media is a secondary event.

Aortic Dissection↗
PubMed1997

A whole genome shotgun gene fusion method for isolation of translation initiation sites in Escherichia coli: identification of Haemophilus influenzae translation initiation sites in E. coli.

We have developed a new method for isolating translation initiation sites based on the expression of Haemophilus influenzae Rd gene fusions with the Escherichia coli galactokinase (galK) gene. We cloned random DNA fragments of H. influenzae Rd DNA into a plasmid vector containing the galK coding sequence from which the translation initiation site (the ribosome binding site and translation initiation codon) had been removed. A subset of the cloned DNA fragments contained translation initiation sites that, when fused to the galK gene, produced active galactokinase and complemented the host galK mutation. Molecules expressing galactokinase activity were isolated and characterized by DNA sequence analysis, and the sequences were aligned with the recently completed whole genomic sequence of H. influenzae Rd. Translation initiation sites for known, hypothetical, and new genes were identified. Translation initiation sites internal to the coding sequences of a number of genes were identified, suggesting that internal translation initiation sites are common, especially in large genes. This shotgun method provides functional information on translation initiation sites and helps to define gene coding sequences.

Amino Acid Sequence↗
PubMed1997

A Pentium personal computer-based craniofacial three-dimensional imaging and analysis system.

Personal computer (PC)-based computing is now ubiquitous in common consumer applications. Although PCs have equaled or surpassed engineering workstations in basic computing power and economy, there is still strong workstation dependency for imaging applications. This article demonstrates that a complete system, based on a Pentium PC (Intel Corporation, Santa Clara, CA) and readily available and inexpensive software, can be built very economically for effective execution of most of the commonly used three-dimensional imaging operations. For the craniofacial application, the Pentium system offers a twofold speed advantage over a Sparc 20 system using similar three-dimensional processing software. The Pentium system allows interactive fuzzy volume rendering, and manipulation and analysis of complex hard and soft-tissue structures.

Equipment Design↗
PubMed1997

[Effects of exposure to hypoxia on the skin temperature and glycogen content of frostbitten feet in rabbits].

Effect of exposure to acute hypoxia and hypoxia for 2 weeks on the skin temperature and content of glycogen of frostbitten feet in rabbits were observed. The results showed that the skin temperatures and content of glycogen were decreased in frostbite at normoxia (FN) group frostbite during acute hypoxia (FAH) group and frostbite hypoxia for 2 weeks (FH-2w) group. After treatment with warm chlorhexidine immersion the skin temperature and glycogen content in treated feet of FN and FAH group were increased, as compared with untreated feet. However, there was no difference between treated and untreated feet in FH-2w group, suggesting that there may be severe disturbance of blood circulation on frostbitten feet under this condition.

Animals↗
PubMed1997

Effect of SR-140333, a neurokinin-1 receptor antagonist, on airway reactivity to methacholine in sedated rats.

AIM: To study the roles of neurokinins in the airway reactivity (AR) to methacholine chloride (MC). METHODS: The effects of (S)-1-(2-[3, 4-dichlorophenyl)-1-(3-isopropoxyphenylacetyl) piperidin-3-yl]ethyl)-4-phenyl-1-azoniabicyclo [2.2.2]octane.chloride (SR-140333), a neurokinin-1 receptor antagonist, on AR to inhaled MC in diazepam-sedated rats, and on MC-induced contraction of isolated tracheal spiral strips were observed. RESULTS: SR-140333 inhibited the increase in respiratory rate (RR) induced by MC aerosol (10-1000 mumol/m3), and the ID50 for inhibiting the response to MC aerosol (1 mmol/m3) was 4.9 micrograms.kg-1 (95% confidence limits 1.4-17.2 micrograms.kg-1). SR-140333 1 mumol.L-1 had no inhibitory effect on MC-induced tracheal contraction. Atropine blocked responses to MC both in vivo and in vitro. CONCLUSION: Endogenous neurokinins are involved in the AR to MC in rats, at least partly mediated via neurokinin-1 receptors.

Albuterol↗
PubMed1997

[Intracerebral grafting of ex vivo transgene muscle cells in rat model of parkinsonism].

The rat model with a unilateral 6-OHDA-induced lesion of the dopaminergic system was used for experimental study on gene therapy for Parkinson's disease (PD). The plasmid pCMVTH (6.04 kb) was constructed as a vector containing the gene of tyrosine hydroxylase (TH) and transferred into cultured primary muscle cells by lipofection ex vivo. After expression of TH was determined in vitro, the intracerebral grafting (ICG) of these genetically modified cells was made in the striatum of PD rat model. The results showed that TH-expressing muscle cells had a long-term survival in the brain and induced a marked decrease in abnormal locomotion and increase in striatal dopamine levels for rat model.

Animals↗
PubMed1997

A clinical study on compound da huang (radix et Rhizoma rhei) preparations for improvement of senile persons' memory ability.

By comparison of the effects of the Compound Tong Jiang Oral Liquid with Da Huang added (TJ [symbol: see text]) and Qi Yin Oral Liquid (QY [symbol: see text]) without Da Huang on senile persons' memory ability, it is discovered that the effects of TJ on shortening the interval between defecations and the duration of defecation, and on improving senile persons' memory ability are significantly better than that of QY (P < 0.05). In addition, TJ can also decrease the serum content of lipid peroxidase and increase the superoxide dismutase activity in red blood cells (RBC). Thus, it is demonstrated that Dahuang and its agents possess the action of anti-senility and can improve mentality.

Aged↗
PubMed1997

[Effects of yizhi pills on memory, superoxide dismutase and malondialdehyde of brain and immunity in mice].

Passive avoidance tests have shown that Yizhi Pills (YZ) markedly improve the memory of normal mice at a dose of 100 mg/kg after oral administration for fifteen days, and significantly reverse the scopolamine, NaNO2 and EtOH-induced disruptions of memory retention in mice at doses of 100, 200, 500 mg/kg after oral administration for five days. In aged mice induced by D-galactose, YZ also significantly improve the impaired memory, increase the activity of SOD and decrease the content of MDA in brain. All these effects were observed at doses of 200, 500 mg/kg after oral administration for forty-one days. YZ significantly promote blood carbon particle clearance, enhance hemolysin antibody in immunodepressed mice induced by cyclophosphamide, and increase earswelling in immunodepressed mice induced by prednisolonum.

Animals↗
PubMed1997

[Effect of SR-140333, a tachykinin NK-1 antagonist, on antigen-induced airway hyperresponsiveness in sensitized rats].

In the present study, the effects of SR-140333, ((S)-1-(2-[3,4-dichlorophenyl)-1-(3-isopropoxyphenylacetyl)piperidin- 3yl]ethyl)-4-phenyl-1-azoniabicyclo[2.2.2]octane.chloride), a nonpeptide antagonist for tachykinin NK-1 receptor, on the antigen-induced airway response to methacholine (MCh) aerosol and airway inflammation in sensitized SD rats were investigated. The baseline respiratory frequencies, tachypnea response to methacholine(MCh), the -log PC30 values of MCh and the leukocyte counts in bronchoalveolar lavage significantly increased after inhalation of 1% oval albumin(OA) aerosol. SR-140333 (152 nmol.kg-1, i.p.) or dexamethasone(368 nmol.kg-1, i.p.), bid x 3 d inhibited these responses. SR-140333 at a low dose of 0.01 mg.kg-1 showed an incomplete inhibition. From these results, we conclude that antigen challenge causes airway hyperresponsiveness and airway inflammation and that tachykinin NK-1 receptor antagonist inhibits these responses.

Animals↗
PubMed1997

[Preliminary studies on proliferation of hemorrhagic fever with renal syndrome virus in Leptotrombidium (L.) Scutellare].

In order to observe further the proliferation and kinetic changes of hemorrhagic fever with renal syndrome virus (HFRSV) in Leptotrombidium (L.) Scutellare infected with HFRSV, the raised Leptotrombidium (L.) Scutellare which were at larve stage or at nymph stage were grinded and sterilized by filtration at interval of 20 days, each batch of the filtrate was inoculated separately to Vero-E6 cells and the titre (TCID50/ml) of HFRSV was measured. The results confirmed: HFRSV were isolated from each batch of larve besides the batch at the 60th days, and the titre of HFRSV was -10(-1)-10(-4); HFRSV were also isolated from two batches of nymph. The isolated HFRSV were amplified by PCR technique and the HFRSV RNA were positive. The above results give rise to evidence that Leptotrombidium (L.) Scutellare might be the transmission vector of HFRSV.

Animals↗
PubMed1997

[The determination of vitamin D in fortified milk and other foods by high performance liquid chromatography (HPLC)].

An HPLC procedure for determination of vitamin D(VD) in fortified milk and food has been developed. The samples were saponified by adding KOH, ethanol and vitamin C at 75 degrees C for 30 min. The digest was extracted with hexane in multistep manner. The extract was washed with 5% KOH, distilled water and 55% ethanol, and evaporated under reduced pressure at 50 degrees C. The residue was dissolved in hexane, transferred to a coentrifuge tube, evaporated under N2 and then dissolved in 200 microL mobile phase. The latter was injected into a silica column (10 microm, 30 cm x 4 mm) for cleanup, eluted with mixture of cyclohexane-hexane containing 0.8% isopropanol and detected at UV 254nm. VD fraction was collected according to the retention time of standard, evaporized under N2, redissolved in 100 microL MeOH, and separated on a C18 column (10 microm, 30 cm x 4 mm) with MeOH/H2O (98:2) as eluent. VD2 and VD3 were eluted as a mixture under the conditions. Recoveries of the method were 94.8% to 99.7%. The average CV (n = 5) for within and between day measurements were 1.6% and 2.1% respectively. This method was already used to determine the content of vitamin D in milk powder, pulvis elementi compound, mixed proteins, dried meat floss, humanized milk power, children health drink, milk wheat powder and fortified milk. The method is simple, rapid and accurate.

Animals↗
PubMed1997

[Development of a SIRI-TOFMS and the application research progress].

The only one set of Sputter Initiated Resonance Ionization-Time of Flight Mass Spectrometer (SIRI-TOFMS) in China was designed and developed. A liquid gallium ion source with micron level diameter of beam, frame-style piezoeletric ceramic sub-micron sample manipulator, a secondary electron imaging system and a computer controlled precise targeting system as well as a real colour big screen image displaying system were added so as to improve its microanalysis capability. By means of this apparatus, trace analysis of Au in minerals and Cu in standard steel samples were carried out. The detection limit of them is 40ng/ and microg/g level, respectively. Aside from the above detections, other preliminary researches ere also performed.

English Abstract↗
PubMed1997

[The relationship between histologic grading of malignancy and regional lymph node metastasis in squamous cell carcinoma of larynx].

Forty cases of squamous cell carcinoma of larynx have been studied by using five factors scale in order to investigate the relation between histologic grading of malignancy and regional lymph node metastasis. The results show that high degree malignancy tumor (which gets more than ten points) and diffusly invased tumor have a significantly higher proportion of regional lymph node metastasis than others. There was no relation between histologic grading of malignancy and T categories. It indicated that histologic grading of malignancy may be a good help in predicting patient evolution.

Carcinoma, Squamous Cell↗
PubMed1997

[A new non-invasive method for measurement of airway responsiveness in sedated rats].

Sprague-Dawley rats sedated with intraperitoneal injection of diazepam (7.5 mg/kg) were placed in a plethysmograph to measure the changes in spontaneous respiration. Inhalation of methacholine (MCh) or acetylcholine (ACh) aerosol did not alter the volume of breathing, but increased respiratory frequency (RF) to the same extent in a concentration-dependent manner. On the other hand, the tachypnea effect of MCh lasted 11 min, and that of ACh only 3 min. Urethane anesthesia inhibited spontaneous respiration and the response to MCh. Atropine, salbutamol and aminophylline inhibited MCh-induced tachypnea. In sensitized rats, the response to MCh was potentiated 6 h after inhalation of ovalbumin aerosol. The results indicate that sedation with diazepam and inhalation of MCh aerosol used in this report are suitable for measuring airway responsiveness in terms of degree of increase of respiratory frequency.

Animals↗