Biomedical subjects

Y Liu

Publications and source records attributed to Y Liu.

At least 991 records · Page 55Linked to original sources

PubMed2000

[Targeting studies of humanized scFv25 fusing to TNFalpha against hepatocellular carcinoma].

OBJECTIVE: To obtain humanized engineering bifunctional antibody, which has potentialities for clinical application. METHODS: Humanized anti-human hepatocellular carcinoma (HCC) single chain fragment (hscFv25) was linked with human TNF-alpha gene to form anti-HCC bifunctional antibody, then it was subcloned into prokaryotic GST fusion expression vector pGEX 4T-1 and expressed in the host E.coli. Indirect immunofluorescent staining was performed on HCC cell smearing slides in order to evaluate the activity of the purified aim protein, then MTT trial to evaluate the cytotoxicity of hscFv25-TNFalpha to SMMC-7721, finally primary tumor regression trial in nude mice bearing HCC to evaluate the targeting therapeutic value of hscFv25-TNFalpha. RESULTS: The hscFv25-TNFalpha had the similar specificity to parental antibody HAb25 for SMMC-7721 antigen. One hour predisposed MTT trial in control with parental antibody HAb25 affirmed that hscFv25-TNFalpha was cytotoxic to targeted cell SMMC-7721 with the IC(50) to be 7.1 microg/ml. The cytotoxicity can be inhibited by parental antibody HAb25. This indicated that the cytotoxicity of hscFv25-TNFalpha to targeted cell is antibody-mediated selective cytotoxicity. The tumor regression trial to the 3mm HCC xenografts in nude mice showed that hscFv25-TNFalpha had assured targeting cytotoxicity and the efficiency was nearly up to 3/3 (1/3 complete remission, 2/3 partial remission). The cytotoxicity of the hscFv25-TNFalpha was better than that of TNFalpha, whose efficiency was only 2/3 and without complete remission. CONCLUSION: hscFv25-TNFalpha is an anti-HCC bi-functional antibody which has potentialities for clinical application.

Animals↗

PubMed2000

P53 regulation and function in normal cells and tumors.

Mechanisms to protect organisms from the consequences of DNA damage include the tumor suppressor p53 pathway. p53 protein binds specifically to a DNA consensus sequence to induce growth inhibitory genes or nonspecifically to damaged sites leading to DNA repair or apoptosis. While p53 protein is susceptible to post-translational modifications and binding to other proteins, few of the modifications or associations have been demonstrated in the context of the cell. We used a novel, sensitive DNA binding assay to examine p53 proteins in lysates prepared from cells responding to DNA damage. Non-transformed progenitor keratinocytes exhibited rapid and sustained induction of activated p53 protein binding to the consensus sequence, correlated with sustained induction of a downstream target gene, the cyclin-dependent kinase inhibitor p21. Binding to a mismatched DNA probe was transient and correlated with total p53 protein in the lysate, suggesting that most or all of the endogenous p53 proteins induced after damage were capable of mismatched DNA binding. Squamous cell carcinoma (SCC) derivates showed defects in induction p53 protein after DNA damage and disproportional losses in DNA binding, compared to total p53 protein steady state levels, along with increased NDN2/p53 association. Maximum induction of endogenous p53 protein binding to the mismatched probe correlated with transcription-independent induction of apoptosis. We suggest a model in which activated forms of p53 carry out transcription-dependent functions in growth arrest and DNA repair which may vary by cell type, while most or all wild type forms of p53 are capable of binding to damaged DNA. p53 protein loss of binding to damaged DNA causes failure of cells to trigger apoptosis and may lead to resistance to chemotherapy. Implications for new directions in therapeutics include functional molecular profiling of individual patient tumors for p53 DNA binding to predict treatment response better than mutational analysis alone and targeted activation of p53 DNA damage binding in tumor cells for increasing their sensitivity to chemotherapy.

Apoptosis↗

PubMed2000

A cardiopulmonary bypass perfusion technique for the surgical repair of aortic type I dissections requiring the elephant trunk procedure.

The effect of cerebral and spinal cord protection by a modified perfusion technique during the elephant trunk procedure was assessed. Between 1997 and 1998, six patients underwent selective cerebral perfusion (SCP) and lower half of the body perfusion (LBP), in which the right subclavian and left femoral arteries were separately cannulated and perfused by individual pump heads. Moderate systemic cooling was used (nasal temp. 20-30 degrees C; rectal temp. 23-26 degrees C). The open distal aortic repair was performed using only the selective cerebral perfusion; while the aortic arch reconstruction was performed using both selective cerebral and lower half of the body simultaneous perfusion. Blood oxygen saturation of the left jugular vein (SjO2) and regional oxygen saturation cerebral (rSO2) in the front region of the brain, was monitored along with the pressure of the left temporal superficial and femoral artery. The mean cardiopulmonary bypass time was 136 minutes, with a mean arrest time of 92 minutes. Mean duration of isolated selective cerebral perfusion was 23 minutes, with flow rates of 5-8 mL/kg/min; a left temporal superficial artery pressure of 50 mmHg; SjO2 65-80%, and rSO2 58-72%. Mean duration of simultaneous selective cerebral and lower half of the body perfusion was 27 minutes; cerebral flow rates 5-8 mL/kg/min; the left temporal superficial artery pressure of 45-50 mmHg; SjO2 70-85% and rSO2 55-76%. At the same time, lower half of the body flow rates were maintained within 30-50 mL/kg/min; with a femoral artery pressure 50-80 mmHg. Mean extubation time was 28 hours; mean ICU time was 4.5 days. There were no neurologic complications in any patient. All patients survived the operation and were discharged from the hospital. This modified perfusion technique of SCP and LBP worked well and provided satisfactory cerebral and spinal cord protection.

Adult↗

PubMed2000

Regeneration of the junctional epithelium and connective tissue after transplantation of detergent-processed allo-teeth.

The authors have developed a new artificial dental implant and evaluated it in a dog model in terms of its potential to produce: I) regeneration of junctional epithelium; II) regeneration and attachment of connective tissue. The implants were constructed from allo-teeth. We removed the cell components from the periodontal ligaments of these teeth with a detergent (1% TritonX-100); the remaining acellular periodontal ligament acted as an extracellular matrix upon which regeneration and attachment could proceed. We placed 10 of these implants in the just-extracted sites of three beagle dogs. We observed regeneration of both junctional epithelium and connective tissue at all implant sites after 3 months. The connective tissue was attached in all cases. Use of the acellular periodontal ligament as an extracellular matrix may facilitate regeneration of host periodontal ligament tissue, thus contributing to recovery of host immunological defense and long-term oral function.

Animals↗

PubMed2000

Plexus between internal mammary graft and pulmonary vasculature after minimally invasive coronary surgery.

We report a complication associated with minimally invasive direct coronary artery bypass grafting surgery The patient suffered a nonfatal anterior myocardial infarction 1 day after he underwent minimally invasive bypass grafting using the internal mammary artery. Two months later, coronary arteriography revealed a fistulous connection between the left internal mammary graft and the left pulmonary vasculature. To our knowledge, this particular complication has not been reported following minimally invasive coronary surgery.

Arterio-Arterial Fistula↗

PubMed2000

[E-selectin mediates early adhesion of HepG2 hepatoma cells to endothelial cells].

OBJECTIVE: To study the role of E-selectin and sLe(x) in the adhesion between hepatoma cells (HepG2) and endothelial cells, and to select drugs capable of inhibiting such adhesion. METHODS: HepG2 cells were vitally stained with fluorescent dye BCECF-AM. Adhesion between the fluorescent HepG2 cells and human umbilical vein endothelial cells (HUVEC) was examined by solid phase adhesion assay in vitro. A number of agents were tested for their effect on the tumor cell-endothelial adhesion. RESULTS: sLe(x) on the surface of HepG2 cells and E-selectin expressed on the surface of HUVEC were necessary for early adhesion. HepG2 cells could activate HUVEC to increase their adhesiveness to HepG2 cells. Dexamethasone, phenylarsenic oxide, levamisole and actinomycin D were able to block the adhesion between HepG2 to HUVEC at low concentrations. CONCLUSION: sLe(x) and E-selectin are important molecules in the early adhesion of hepatoma cells to HUVEC. Cytokine-like factors of HepG2 origin are likely involved in the activation of endothelial cells in the target tissue. Agents capable of inhibiting NF kappa B can be hopefuly used as anti-adhesion drugs to inhibit metastasis of liver cancer.

Animals↗

PubMed2000

[Protection of hematopoietic cells against toxicity of anticancer agents by transfecting mdr1 gene into bone marrow cells].

OBJECTIVE: To investigate whether the hematopoietic cells can be protected from the toxic effect of anticancer agents by transfecting mdr1 gene into bone marrow cells. METHODS: The mdr1 gene was transfected into murine and human bone marrow cells by Lipofectin. Expression of mdr1 was assessed by RT-PCR and flow cytometry. The functional activity of mdr1 in transfected cells was examined by rhodamine retention assay. Resistance to chemotherapeutic drugs of human and murine mdr1 gene transfected bone marrow cells was ascertained in vivo and that of murine cells was assessed in vivo in a bone marrow transplantation model. RESULTS: Multidrug resistance 1 gene was successfully transfected into and expressed in murine and human bone marrow cells. The transfected cells were resistant to doxorubicin; Vp-16, vincristine and colchicine. Bone marrow cells transfected with mdr1 gene reconstituted the hematopoietic function and offered resistance to doxorubicin in recipient mice. CONCLUSION: To transfect mdr1 gene into bone marrow cells is a promissing approach to protect bone marrow cells from the myelosuppressive effect of chemotherapeutic agents.

Animals↗

PubMed2000

Training of junior rowers before world championships. Effects on performance, mood state and selected hormonal and metabolic responses.

BACKGROUND: Few data have been published on training of competitive athletes and about metabolic, hormonal and psychological reactions to overreaching (transient over-training) and tapering in successful athletes. METHODS: Training was recorded and effects on mood state and metabolic and hormonal responses were examined in 10 rowers and spares of the coxed eight during preparation for the World Championships 1995. Mood state was determined using the Recovery-Stress-Questionnaire for Athletes. Resting morning blood parameters as well as performance were measured every week over a period of five weeks. RESULTS: Very high training loads of approximately 3.2 hours per day were sustained for 18 days. Maximum performance (Pmax) and maximum lactate (Lamax) were decreased during high-load training phases (overreaching), Pmax, Lamax and endurance increased after the tapering period. There were decreases in gonadal and hypothalamic steroid hormones (fsh, 1h, prolactin, testosterone) during overreaching and increases in these hormones in tapering. Both performance and hormonal indices of training load were reflected by deterioration of recovery in the Recovery-Stress-Questionnaire for Athletes. CONCLUSIONS: Clear signs of overreaching were found after 18 days of intense training of about 3 h.d(-1) in these highly-trained athletes, i.e. decreases in performance, gonadal and hypothalamic steroid hormones and deterioration of recovery in the psychological questionnaire. After tapering values returned to baseline values before the World Championship. The findings indicate that overreaching is an integral part of successful training regimens and can be analyzed by a multi-factorial approach involving biological and psychometric data.

Adolescent↗

PubMed2000

Factors related to the efficacy of an adjustable oral appliance for the treatment of obstructive sleep apnea.

AIM: The purpose of this study was to investigate whether any physiological or cephalometric parameters could be used to predict the efficacy of the Klearway oral appliance (OA) for the treatment of obstructive sleep apnea (OSA). METHODS: Forty-two male and 5 female patients with OSA were recruited on the basis of baseline polysomnography with a documented Apnea and Hypopnea Index (AHI) > 15 per hour. Repeat polysomnography was performed with the appliance in place. Baseline cephalometry was performed for each patient. Subjects were divided into 3 groups on the basis of the degree of change in AHI with OA therapy: good response (> 75% decrease in AHI), moderate response (25% to 75% decrease range in AHI), and poor response (< 25% decrease in AHI). RESULTS: Patients with a good response were younger and had smaller upper airways. A stepwise regression analysis revealed that a better treatment response with the Klearway appliance was obtained in patients who were younger and had a lower body mass index, a longer maxilla, a smaller oropharynx, a smaller overjet, less erupted maxillary molars, and larger ratio of vertical airway length to the cross-sectional area of the soft palate.

Adult↗

PubMed2000

[Evaluation of red cell mean corpuscular volume and simple tube red cell osmotic fragility quantitative test in detection of thalassemia].

OBJECTIVE: To evaluate and compare the detection efficiency of red cell mean corpuscular volume(MCV) test against simple tube red cell osmotic fragility quantitative test(STROFQT) in diagnosis of thalassemia. METHODS: 1978 subjects (989 couples) were detected by both MCV test and STROFQT, 158 samples from subjects were tested by alpha,beta-thalassemia DNA polymerase chain reaction(PCR) and serum ferritin test. RESULTS: The positive rate (9.0%), sensitivity (98.9%) of MCV test were higher than those of STROFQT (8.1%, 88.6%) (P < 0.05). The specificity of MCV test showed no statistic significance compared with that of STROFQT (P > 0.05). CONCLUSION: Both MCV test and STROFQT served as helpful approaches in detection of thalassemia, MCV test shows better diagnostic efficiency for screening than STROFQT.

Adult↗

PubMed2000

[Analysis of wavelet scalogram of blood flow ultrasonic Doppler signal].

OBJECTIVE: To study the power spectrum density of blood flow ultrasonic Doppler signal using wavelet analysis. METHOD: Doppler signal of blood flow in human common carotid artery was studied with wavelet scalogram analysis, an affine smoothing Wigner-Ville transform with a constant "Q" character. RESULT: Wavelet scalogram of blood flow ultrasonic signal had a higher distinguishability than STFT spectrogram in the low frequency portion, but had poorer decussation terms than spectrogram. CONCLUSION: It is practicable to estimate the spectrum of Doppler signals of blood flow by the wavelet analysis method. And this can be used in low speed blood flow for higher resolution of spectrum in the low frequency portion.

Aerospace Medicine↗

PubMed2000

[Application of the scrotal axial skin flap in hypospadias repair].

OBJECTIVE: To present a new and reliable method for treatment of failed hypospadias repair. METHOD: The scrotal axial skin flap based on anterior scrotal vessels was designed and used in reconstruction of the urethra. 7 patients with failed hypospadias repair have been treated with this method since 1996. RESULT: There was no any complication in all the patients. CONCLUSION: The advantages of this method are that the flap has good blood supply and the potentiality of growth. It is suitable for treatment of hypospadias, especially the failed hypospadias repair.

Adolescent↗

PubMed2000

[Repair of rectovaginal fistula using pudendal-thigh flap pedicled on the obturator artery].

OBJECTIVE: This is to introduce a new method for repair of rectovaginal fistual. METHODS: On the basis of an anatomical study a new type of the pudendal-thigh flap pedicled on the obturator artery has been designed to repair rectovaginal fistual. RESULTS: 4 patients were treated with this method. All flaps survived and the fistula between vagina and rectum was closed primarily. CONCLUSIONS: The advantages of the pudendal-thigh flap pedicled on the obturator artery include: 1. Good blood supply; 2. Relative thin and hairless; 3. Perfect hiding of the donor site. We think that it is one of the best methods of rectovaginal fistula repair.

Adult↗

PubMed2000

[Lower lid blepharoplasty by using the principles of plastic surgery and the technique of orbital fat release].

OBJECTIVE: To create a new method for lower lid blepharoplasty in order to prevent the complication of lower lid ectropion after the operation. METHODS: Eight patients with 16 eyelids were undergoing the lower lid blepharoplasty with the use of plastic surgery principles and the technique of orbital fat release. The following-ups were carried out in each patient. RESULTS: Eight patients with 16 eyelids were treated with the above-mentioned technique. The satisfactory results were achieved with good appearance. CONCLUSION: The above-mentioned technique is a safe, simple and effective method for the lower lid blepharoplasty.

Adult↗

PubMed2000

[An introduction to literature on infantile asthmatic coughing in the period of Sui - Tang to Song dynasties].

Records in Zhu bing yuan hou lun are the primary accumulation of materials on infantile asthmatic coughing. The material from Bei ji qian jin yao fang and Qian jin yi fang were based on the author's life - long practical experience and applied by later generations. The guideline based on differential diagnosis of zheng for treating this ailment was established by Xiao er yao zheng zhi jue. While You you xin shu contains the most rich and detailed materials for this ailment before the Song dynasty, which, exerting profound influence on later generations in this field, is a milestone in the history of academic development of infantile asthmatic coughing.

Asthma↗

PubMed2000

[Seed rain and seed bank of constructive species in evergreen broadleaved forest at Chongqing Simian Mountain].

The study shows that the early and late seed rains of constructive tree species in evergreen broadleaved forest at Chongqing Simian Mountain had no activity. The bigger the seeds of the species and the earlier or later the seeds of the species matured, the higher the proportion of the seed rain damaged by animals. The quantitative variation of seed rain, active seed rain and seed bank did not take place at the same time. At early time, the number of seed banks of Castanopsis fargesii, Lithocarpus glabra, Quercus myrsinrefolia, Castanopsis plasyacantha, Cinamomum subavenium which own more active seed rain increased by geomitric series. The seed banks of Castanopsis orthacantha and Schima argentea were small, only survived a short time, and did not sprout next year. The quantitative dynamics of seed banks and their increasing or decreasing rates were decided by the proportion damaged by animals, dying speed of seeds and their resistance to pathogens and adverse circumstances, and the state of seed germination.

Biological Specimen Banks↗

PubMed2000

[Species composition and distribution of algae in semi-desert algal crusts].

Twenty-two species of algae, including 10 Cyanophyta, 4 Chlorophyta, 6 Bacillariophyta and 2 Euglenophyta, were isolated and identified from the semi-desert algal crusts in Shapotou, Ningxia Autonomous Region. The relationship between algae and soil matrix was studied by grinding and superprobe, and the distribution of algal species in eight layers of crusts was examined under light and scanning electron microscopes. It was found that the algae exhibited a layer-typed distribution in intermicron, and the layers of algal crust from surface to inner were in order of inorganic mineral protection layer(ca. 0.02 mm), alga-enriched layer(0.02-2.5 mm) and sparse algae layer(2.5-5.0 mm). The filaments of algae were united with clay mineral by the polysaccharides and protein of their sheath, or extended directly into mineral granules to network and band sand and soil particles.

Climate↗

PubMed2000

[Net photosynthetic rate of two species of wintering host mosses for gullaphids and its response to light, temperature and water content].

The net photosynthesis of Thuidium cymbifolium and Chrysocladium retrorsum, two species of wintering host mosses for gullaphids, and its response to light, temperature and water content were measured with CI-301PS(CID Inc. USA) both in winter and spring. The photosynthetic capacity of Thuidium cymbifolium and Chrysocladium retrorsum was about 141 and 117 mumolCO2kg-1dw.s-1, respectively, and trended to increase from winter to spring. The light saturation point of these two mosses at 800-900 mumol.m-2.s-1 was much higher than that of many other mosses, and the compensation point ranged from 40 to 50 mumol.m-2.s-1. The temperature response curves of these two mosses were similar, with optium temperature ranging from 25 to 36 degrees C in spring, and from 20 to 30 degrees C in winter. When the temperature was below the freezing point(-15 to 0 degree C), they both maintained a distinct net photosynthesis, with the optimum water content ranging from 200 to 300(400)% dw. The photosynthesis started to be restrained evidently, when the water content declined to about 150% dw. The gas exchange ceased or became negative, when the water content was as low as 40-50% dw. It can be inferred that these two species might be both poikilothermal and poikilohydric organisms, but the resistibility of T. cymbifolium to intense light and high temperature was higher than that of C. retrorsum.

Animals↗