Biomedical subjects

X Xiao

Publications and source records attributed to X Xiao.

At least 55 records · Page 3Linked to original sources

PubMed2001

Three-dimensional ultrasonography in obstetrics: the clinical value.

To investigate the clinical value of three-dimensional ultrasonography (3DUS) in obstetrics, various 3DUS rendering methods including surface mode, transparent mode and multiplanar mode were employed to scan 30 fetuses in second and third trimester by using the transabdominal volume transducer. The results showed that surface mode could vividly demonstrate the surface morphologic features of the fetuses, as well as the stereo-shape and the spatial relationship among the surface structures. The face, limbs, umbilical cord and outer genitalia of the fetus could be well displayed by surface mode. Transparent mode could reveal the bony structures under the surface, such as ribs, vertebrae, crania, etc. The result was not affected by the sophisticated curvature of these bony structures and the success rate was up to 100%. When rendered by multiplanar mode, the region of interest (ROI) could be viewed from different directions. It should be concluded that 3DUS could serve as a supplement to two-dimensional ultrasonography (2DUS). 3DUS might play an important role in prenatal diagnosis and enhance the diagnostic confidence level of the physicians.

Female↗

PubMed2001

The study of ovarian artery hemodynamics in patients with infertility by color Doppler energy.

Seventy-four cases of infertility were examined to study the hemodynamics of the bilateral ovarian arteries at 21st day during the corpus luteum phase by color Doppler energy(CDE) and color Doppler flow imaging (CDFI). All the patients were verified by laparoscopy, fallopian tube patency examination and ovarian function test. Twenty-two healthy women served as controls. The results showed that the difference of resistance index(RI) and pulsatility index (PI) of bilateral ovarian arteries between the infertility and the normal controls had statistical significance (P < 0.01), and the PI showed negative correlation with the thickness of endometrium (left side: r = 0.724, P < 0.01; right side: r = 0.756, P < 0.01). The results also showed that CDE was more sensitive than CDFI in displaying the ovarian arteries. It could be concluded that the elevated resistance of ovarian artery during the corpus luteum phase was one of the important factors that resulted in infertility.

Adult↗

PubMed2001

Study of laser vas deferens occlusion.

The objective of this study was to determine threshold levels for high-power laser output Nd:YAG laser photocoagulation and to determine the possible reversibility of laser vas occlusion. The study included vas deferens of 220 rabbits and 20 samples of men in vitro, applying the Nd:YAG laser instrument, doing vasopuncture by a catheter needle, guiding the fiber into the vas, and performing the irradiation occlusion experiment to determine effective threshold value of photocoagulation. The effect and safety of occlusion were followed-up over a year, and reopening a experiment was done in 60 occluded nodes of rabbits. The postoperative sperm disappearance rate was 100%, and reopening rate was 72.7% without obvious complications. High-power lasers may be used as photocoagulation, and its merits are reliable, effective, and rapid recovery. The vas threshold lesion value of rabbits and men in vitro are 50 W/0.5 s, 45 W/1 s, respectively, and irradiation depth reached the middle-ring muscularis.

Animals↗

PubMed2001

Apolipoprotein B secretion and atherosclerosis are decreased in mice with phospholipid-transfer protein deficiency.

Increased secretion and levels of ApoB-containing lipoproteins (BLp) commonly occur in familial hyperlipidemia, obesity and diabetes. The plasma phospholipid-transfer protein (PLTP) is known to mediate transfer of phospholipids between BLp and HDL during their intravascular metabolism. To address a possible role of PLTP in dyslipidemia and atherogenesis, we bred mice deficient in the gene encoding PLTP (PLTP-deficient mice) using different hyperlipidemic mouse strains. In ApoB-transgenic and ApoE-deficient backgrounds, PLTP deficiency resulted in reduced production and levels of BLp and markedly decreased atherosclerosis. BLp secretion was diminished in hepatocytes from ApoB-transgenic PLTP-deficient mice, a defect that was corrected when PLTP was reintroduced in adenovirus. The studies reveal a major, unexpected role of PLTP in regulating the secretion of BLp and identify PLTP as a therapeutic target.

Animals↗

PubMed2001

Combined IL-12 and GM-CSF gene therapy for murine hepatocellular carcinoma.

Among various immunotherapeutic approaches, interleukin-12 (IL-12) is particularly appealing because of its superior antitumor effects, which have been demonstrated in preclinical as well as clinical studies. However, IL-12 therapy was often accompanied by severe side effects due mainly to the supranormal induction of interferon-gamma. To optimize the therapeutic efficacy and lower the side effects of IL-12, we have investigated the antitumor activity of combined IL-12 and granulocyte-macrophage colony-stimulating factor (GM-CSF) gene therapy in a highly malignant and poorly immunogenic murine hepatocellular carcinoma model. Using a versatile hydrodynamics-based DNA delivery method, we showed that the combined gene delivery of IL-12 and GM-CSF induced very strong antitumor cellular immunity and achieved significant therapeutic efficacy, whereas each cytokine gene alone yielded appreciable but less effects. We also observed that the combined therapy induced lower levels of interferon-gamma than did IL-12 alone. These results suggest that combined IL-12 and GM-CSF therapy can render a stronger antitumor effect as well as lowering potential side effects.

Animals↗

PubMed2001

The role of receptors in the maturation-dependent adenoviral transduction of myofibers.

One of the major hurdles facing the application of adenoviral gene transfer to skeletal muscle is the maturation-dependent transduction of muscle myofibers. It was recently proposed that the viral receptors (Coxsackie and adenovirus receptor (CAR) and the integrins alphavbeta3/beta5) play a major role in the poor adenoviral transduction of mature myofibers. Here we report the findings of morphological studies designed to determine experimentally the role of receptors in the adenoviral transduction of mature myofibers. First, we observed that the expression of both attachment and internalization receptors did not change significantly during muscle development. Second, when an extended tropism adenoviral vector (AdPK) that attaches to heparan sulfate proteoglycan (HSP) is used, a significant reduction of adenoviral transduction still occurs in mature myofibers despite HSP's high expression in mature skeletal muscle fibers. Third, when the adeno-associated virus (AAV) is used, which also utilizes HSP as a viral receptor, muscle fibers at different maturities can be highly transduced. Fourth, the pre-irradiation of the skeletal muscle of newborn mice to inactivate myoblasts dramatically decreased the transduction level of Ad and AdPK, but had no effect on AAV-mediated viral transduction of immature myofibers. These results taken together suggest that the viral receptor(s) is not a major determinant in maturation-dependent adenoviral transduction of myofibers.

Adenoviridae↗

PubMed2001

Screening for CRX gene mutations in Chinese patients with Leber congenital amaurosis and mutational phenotype.

PURPOSE: To screen for possible disease-causing mutations in the CRX gene in Chinese patients with Leber congenital amaurosis (LCA) and to enrich the understanding of its mutational phenotype. METHODS: Genomic DNA was collected from 27 patients with LCA. The coding sequences of the CRX gene were analyzed using the PCR-heteroduplex-SSCP method. Mutations were confirmed by DNA sequencing. RESULTS: We identified two heterozygous variations in the CRX gene in two patients with LCA. One was a deletion (GCC-->-CC, A181D1bp) leading to a frameshift and protein truncation. This mutation was present in a patient with LCA, but not in his healthy parents. The ocular manifestations of this A181Delta1bp mutation are described. An intronic variation (IVS1-13G-->C) was found in a patient with LCA as well as in his healthy father. CONCLUSION: A heterozygous A181D1bp mutation in the CRX gene caused an LCA phenotype in a Chinese patient.

Asian People↗

PubMed2001

Adeno-associated virus-mediated delivery of glial cell line-derived neurotrophic factor protects motor neuron-like cells from apoptosis.

Motor neuron disorders including amyotrophic lateral sclerosis may benefit from the induction of neurotrophic factors such as glial cell line-derived neurotrophic factor (GDNF) that are known to be trophic and protective for motor neurons. However, the application of such factors is limited by an inability to successfully target their expression in the nervous system. In this study we investigate the potential of using adeno-associated virus (AAV) as a vector for gene delivery into motor neuron-like cells. In initial experiments on the motor neuron cell line NSC-19 using a recombinant AAV vector expressing the reporter gene beta-galactosidase (AAV-LacZ), we successfully demonstrate the utility of AAV for gene transfer. In addition, a recombinant AAV vector expressing GDNF was shown to express and secrete high levels of the neurotrophic factor into the surrounding media of NSC-19 infected cells. Finally, the AAV-GDNF vector is demonstrated to act in a neuroprotective fashion. Withdrawal of trophic support from NSC-19 cells through serum deprivation results in a subsequent increase in the number of cells entering apoptosis. However, the percentage of apoptotic cells are significantly reduced in cells infected with the AAV-GDNF vector, as compared to AAV-LacZ or uninfected controls. This work demonstrates the potential of using AAV as a vector in motor neuron-like cells and should prove important in devising future gene therapy strategies for the treatment of in vivo motor neuron disorders.

Animals↗

PubMed2001

Numerical simulation of enhanced external counterpulsation.

Enhanced external counterpulsation (EECP) is a noninvasive, counterpulsative method to provide temporary aid to the failing heart by sequentially inflating cuffs on the lower extremity out-of-phase with the left ventricle. Optimization of the method necessitates consideration of the hemodynamics created by EECP and the mode of action providing patient benefit. A computational model based on the governing one-dimensional equations is developed that simulates cardiovascular hemodynamics during EECP. The model includes a 30-element arterial system including the left ventricle, bifurcations, and peripheral arterial vessels. Effects of vessel collapse as external pressure is applied, arterial refilling on pressure release, changes in aortic pressure, and shear stress generated in the arteries are each investigated. Device parameters are systematically varied to determine their effect on system performance. Results show the potential for significant collapse and shear augmentation throughout the arteries of the lower extremity. Performance is strongly influenced by the mean level of external pressurization and the timing of cuff inflation, but less so by the relative timing and pressure differences between cuff segments.

Biomedical Engineering↗

PubMed2001

An electrochemical quartz crystal impedance study on the rising of an aqueous solution meniscus for a partially immersed gold electrode during the electrochemical reduction of oxygen.

An electrochemical quartz crystal impedance system (EQCIS) was used to study the resonance behavior of an AT-cut 9-MHz piezoelectric quartz crystal (PQC) with its Au electrode partially immersed in KCl, Na2SO4 and NaClO4 aqueous solutions, respectively. An in situ determination of the immersed area and the height of the electrode was achieved by simultaneous measurements of the PQC electroacoustic admittance and the electrochemical impedance. The rising of the solution meniscus for a gold electrode partially immersed in aqueous solutions was found at oxygen reduction potentials and evaluated versus the electrolyte, electrolyte concentration, solution pH and oxygen concentration. The solution meniscus rising was explained based on a lowering of the contact-angle hysteresis and a continued collection of the water product at the solid-gas-solution interface during oxygen reduction.

Journal Article↗

PubMed2001

[Cases-Control association study and transmission disequilibrium test of T102C polymorphism in 5HT2A and Tourette syndrome].

OBJECTIVE: To investigate whether T102C polymorphism in 5HT2A (serotonin receptor 2A) is associated with Tourette syndrome. METHODS: Both case-control association analysis and Transmission Disequilibrium Test(TDT), in addition to polymerase chain reaction and RFLP technique were used in 157 trios with Tourette syndrome (TS) and 120 controls. A semi-structured "Schedule for Tourette and other behavioral syndrome" was used in family history-collecting. Both the criteria of "Diagnostic and Statistical Manual of Mental Disorders"(DSM-IV) and that of Tourette syndrome association (TSA) were used in the diagnosis of Tourette syndrome and related disorders. RESULTS: The association between T102C polymorphism in 5HT2A and Tourette syndrome comorbided with obsessive compulsive disorder (OCD) was found by genotype-wise analysis (chi(2)=8.38,P=0.004) and allele-wise analysis (chi(2)=4.84,P=0.028), which was further confirmed by TDT analysis (chi(2)=5.12,P=0.02). No evidence of association or transmission disequilibrium between 102T/C polymorphism in 5HT2A and this disease in pure TS and total TS sample was found. CONCLUSION: 102T/C polymorphism in 5HT2A is exclusively associated with Tourette syndrome comorbided with DSM-IV OCD, which may constitute an independent subtype of Tourette syndrome.

Adolescent↗

PubMed2001

[Cloning the differentially expressed genes in the retina of rds mouse during the development of retinitis pigmentosa].

OBJECTIVE: To clone the differentially expressed genes in the retina of rds mouse (the animal model of congenital retinitis pigmentosa) during the disease development. METHODS: The retinal mRNA of rds mouse during the development of retinitis pigmentosa was analyzed by the mRNA differential display. The differentially expressed mRNA fragments were cloned and sequenced. RESULTS: There was obvious difference of gene expression between rds mouse and the control during the development of retinitis pigmentosa. Five differentially expressed bands were cloned and sequenced. One of those had 86% identity (132/154) with the sequence of the human cDNA DKFZp434D1227 from adult testis in GenBank, which was submitted lately (15-Oct-1999) and without much information. The other had lower identity with the sequences in GenBank. A highly expressed clone in the rds mouse on postnatal day 25 had the same length as another clone in the normal on postnatal day 37, which was not expressed in the rds mouse on day 37. The sequences of the two clones were identical in all but two base pairs. CONCLUSION: These results indicate that there are a lot of novel differentially expressed genes in the chronic processing diseases, such as retinitis pigmentosa.

Animals↗

PubMed2001

Suppression of choroidal neovascularization by adeno-associated virus vector expressing angiostatin.

PURPOSE: To test the efficacy of a recombinant adeno-associated virus (rAAV) vector that expresses mouse angiostatin in suppressing experimental choroidal neovascularization (CNV) in a rat model. METHODS: An rAAV vector, rAAV-angiostatin, was constructed to deliver the mouse angiostatin gene. rAAV-angiostatin and a control virus, rAAV-lacZ, were delivered in vivo by subretinal injection in Brown Norway rats, and the delivery was confirmed by reverse-transcriptase polymerase chain reaction (RT-PCR). For a CNV suppression experiment, CNV was generated by fundus krypton laser photocoagulation 7 days after the viral vector injection and was evaluated by fluorescein angiography (FA) and histology. Apoptosis in retina was analyzed using the TUNEL assay. Inflammation in the retina was investigated by immunohistochemistry, using antibodies that recognize lymphocytes. RESULTS: rAAV-angiostatin injection led to sustained expression of the angiostatin gene in chorioretinal tissue for up to150 days. FA analysis revealed significant reduction of the average sizes of CNV lesions in rAAV-angiostatin-injected eyes when compared with rAAV-lacZ-injected eyes at both 14 (P = 0.019) and 150 (P = 0.010) days after injection. Moreover, histologic analysis of CNV lesions also revealed significantly smaller lesions in rAAV-angiostatin-injected eyes (P = 0.004). As for adverse effects, rAAV-angiostatin injection did not cause inflammation or apoptosis of cells in retina and choroid. CONCLUSIONS: This is the first report that subretinal injection of rAAV-angiostatin can significantly reduce the sizes of CNV lesions. This and the absence of apoptosis and inflammation in chorioretinal tissue indicate the feasibility of a gene therapy approach for treatment of CNV disease.

Angiostatins↗

PubMed2001

[Penetrance of Leber hereditary optic neuropathy in Chinese individuals with mitochondrial DNA 11778 mutation].

OBJECTIVE: To analyze the penetrance of Leber hereditary optic neuropathy (LHON) in families with homoplasmic mitochondrial DNA (mtDNA) 11778 mutation. METHODS: Maternal relatives of 16 families were analyzed based on ocular phenotype and primary mtDNA mutation analysis. RESULTS: One hundred and thirty individuals from the 16 families harbored the 11778 mutation. Of the 130 individuals, 65 were male and 65 female. Forty-three individuals (34 male and 9 female) were affected with LHON. The penetrance of LHON in the 16 families ranged from 13.3% to 66.7%, with an average penetrance of 33.1%. Males, with an average penetrance of 52.3%, were more affected than females who had an average penetrance of 13.8%. About 79% of the affected individuals were male with a male to female ratio of 3.8: 1. The number of affected females found in the families analysis is greater than that in the probands analysis where only 3 of 41 probands with LHON and mtDNA11778 mutation were female(male to female ratio =12.7:1). CONCLUSION: The penetrance of LHON in Chinese individuals with homoplasmic mtDNA11778 mutation is about one third,which is within the range of that in Caucasion.

DNA Mutational Analysis↗

PubMed2001

[The expression of tyrosine-kinase receptor flk-1 and hypoxic pulmonary vascular remodeling in the lung of rats exposed to hypoxia].

OBJECTIVE: To assess the role of tyrosine-kinase receptor flk-1 in the development of hypoxic pulmonary vascular remodeling. METHODS: We divided 20 male Wistar rats into two groups(control vs hypoxia) and exposed them to normoxic condition and isobaric hypoxia for 3 weeks respectively. The pulmonary artery pressure was measured by right cardiac catheterization. The expression of flk-1 in lung tissues was measured by immunohistochemical staining. Histologic sections of the lungs were examined by a computerized image analyser. RESULTS: In hypoxic rats, the pulmonary artery pressure was significantly raised to a higher level, P < 0.01; the cell number of vascular wall was significantly increased. The results also demonstrated that chronic hypoxia brought about the significant increment in thickness of wall with narrowing of lumen of pulmonary arterioles, and the increment in the percent of vascular wall thickness/vascular external diameter (WT%) and the percent of vascular wall area/total vascular area (WA%), P < 0.01. The positive staining of flk-1 in the wall of pulmonary arteriole of rats treated with hypoxia was significantly stronger than that of normal rats, P < 0.01. Positive correlations were seen between the increment of expression of flk-1 with WT% and WA% (r = 0.714, 0.738, P < 0.01). CONCLUSION: Chronic hypoxia can induce an increasing expression of flk-1, and the flk-1 may play an important role in the pathogenesis of hypoxic pulmonary vascular remodeling.

Animals↗

PubMed2001

[A study of analyzing short-chain fat acid by gradient reversed-phase high-performance liquid chromatography].

OBJECTIVE: The objective of this study is to obtain the optimized separating conditions of formic acid, acetic acid, propionic acid, butyric acid, valeric acid, lactic acid, succinic acid from bacteria using reversed-phase high performance liquid chromatograph (RP-HPLC), and to set up a reliable progress in identifying the end-products of oral bacteria. METHODS: The conditions of separating seven short-chain fat acids were optimized using the method of gradient RP-HPLC. RESULTS: The study showed that the optimal chromatographic parameters were: 1.0 ml/min and 2.0 ml/min of flow rates, and the wavelength of ultraviolet detection was 217 nm. The composition of eluent: the ratio of phosphate buffer (pH 2.8) to methanol is 95:5 (v/v), gradient 5%-50%. The liner gradient wash will be performed in 10 minutes at room temperature. The average recovery rate was 92%, and RSD was 1.8%. CONCLUSION: The results of this paper will be helpful to determine acid composition of end products of oral bacteria.

Chromatography, High Pressure Liquid↗

PubMed2001

[Effects of para-aminobenzoic acid (PABA) on growth of Streptococcus mutans].

OBJECTIVE: The aim of this study is to examine effects of para-aminobenzoic acid (PABA) on the growth of Streptococcus mutans (S. mutans). METHODS: Different concentrations of PABA (10(-10)-10(-3) g/L) were separately transferred to modified Carlsson medium. S. mutans (ATCC 25175) grew in modified Carlsson medium with different concentrations of PABA. All cultures were incubated at 37 degrees C anaerobically in an atmosphere of 80% of nitrogen (v/v), 10% of hydrogen (v/v) and 10% of carbon dioxide (v/v) for 48 hours. The absorbance values of S. mutans were measured by using a spectrometer (UV-1601). The colony forming units (CFU) were obtained by growing S. mutans in media with different concentrations of PABA (10(-10)-10(-3) g/L). RESULTS: Different concentrations of PABA had different stimulating effects on the growth of S. mutans (P < 0.05). But this kind of stimulating effects declined when the concentration of PABA was 10(-3) g/L. CONCLUSION: This experiment indicates PABA has stimulating effects on the growth of S. mutans, and PABA can promote growth of S. mutans.

4-Aminobenzoic Acid↗

PubMed2001

[Effects of para-aminobenzoic acid (PABA) on growth of Lactobacillus acidophilus].

OBJECTIVE: The aim of this study is to examine effects of para-aminobenzoic acid (PABA) on the growth of Lactobacillus acidophilus (L. acidophilus). METHODS: Different concentrations of PABA (10(-10)-10(-3) g/L) were separately transferred to the modified Carlsson medium. L. acidophilus (ATCC4356) grew in these Carlsson media. All cultures were incubated at 37 degrees C anaerobically in atmosphere of 80% of nitrogen, 10% of hydrogen, and 10% of carbon dioxide for 48 hours. Absorbance values (lambda = 540 nm) of bacterial suspensions were measured using a spectrometer (UV-1601). Colony forming units (CFU) were obtained by growing L. acidophilus in Carlsson media with different concentration of PABA (10(-10)-10(-3) g/L). RESULTS: Different concentrations of PABA (10(-10)-10(-4) g/L) had different stimulating effects on the growth of L. acidophilus (P < 0.05). But stimulating effects declined, when PABA concentration was 10(-5) g/L, and when the concentration of PABA reached 10(-3) g/L, the stimulating effect disappeared. CONCLUSION: This study indicates PABA stimulates the growth of L. acidophilus, and PABA can promote growth of L. acidophilus.

4-Aminobenzoic Acid↗