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Biomedical subjects

J Yao

Publications and source records attributed to J Yao.

At least 181 records · Page 10Linked to original sources
PubMed1998

Three-dimensional echocardiography in ischemic heart disease.

The ability of two-dimensional echocardiography to detect and to evaluate the extent of wall motion abnormalities is limited by the use of few selected, nonparallel, views of the whole left ventricle. This leads to an incomplete appreciation of the spatial relationships between various cardiac structures and inaccuracy in quantitative data as a result of using of geometric assumptions. Dynamic volume-rendered three-dimensional echocardiography has the ability to overcome the above limitations. In this article we review the use of volume-rendered three-dimensional echocardiography in the diagnosis and assessment of ischemic heart disease, including complications related to myocardial infarction.

Echocardiography, Three-Dimensional↗
PubMed1998

Molecular genetic study of the interaction of Sindbis virus E2 with Ross River virus E1 for virus budding.

Glycoprotein PE2 of Sindbis virus will form a heterodimer with glycoprotein E1 of Ross River virus that is cleaved to an E2/E1 heterodimer and transported to the cell plasma membrane, but this chimeric heterodimer fails to interact with Sindbis virus nucleocapsids, and very little budding to produce mature virus occurs upon infection with chimeric viruses. We have isolated in both Sindbis virus E2 and in Ross River virus E1 a series of suppressing mutations that adapt these two proteins to one another and allow increased levels of chimeric virus production. Two adaptive E1 changes in an ectodomain immediately adjacent to the membrane anchor and five adaptive E2 changes in a 12-residue ectodomain centered on Asp-242 have been identified. One change in Ross River virus E1 (Gln-411-->Leu) and one change in Sindbis virus E2 (Asp-248-->Tyr) were investigated in detail. Each change individually leads to about a 10-fold increase in virus production, and combined the two changes lead to a 100-fold increase in virus. During passage of a chimeric virus containing Ross River virus E1 and Sindbis virus E2, the E2 change was first selected, followed by the E1 change. Heterodimers containing these two adaptive mutations have a demonstrably increased degree of interaction with Sindbis virus nucleocapsids. In the parental chimera, no interaction between heterodimers and capsids was visible at the plasma membrane in electron microscopic studies, whereas alignment of nucleocapsids along the plasma membrane, indicating interaction of heterodimers with nucleocapsids, was readily seen in the adapted chimera. The significance of these findings in light of our current understanding of alphavirus budding is discussed.

Amino Acid Sequence↗
PubMed1998

NO decreases phosphorylation of focal adhesion proteins via reduction of Ca in rat aortic smooth muscle cells.

Our laboratory has previously reported that the antimitogenic effect of nitric oxide (NO) in primary cultures of rat aortic smooth muscle cells may be attributed to activation of protein tyrosine phosphatase and dephosphorylation of protein phosphotyrosine [G.S. Dhaunsi, C. Matthews, K. Kaur, and A. Hassid, Am, J. Physiol. 272 (Heart Circ. Physiol. 41): H1342-H1349, 1997]. The goal of the current study was to investigate the role of cytoplasmic Ca in this process and to identify protein substrates that are dephosphorylated by treatment with NO. Treatment of primary rat aortic smooth muscle cell cultures with the NO donor S-nitroso-N-acetylpenicillamine (SNAP) decreased cytoplasmic Ca levels and elicited phosphotyrosine dephosphorylation. Both effects were mimicked by the extracellular and intracellular Ca chelators ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid (EGTA) and 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (BAPTA), respectively, and by the Ca channel blocker nifedipine. Conversely, elevation of cytoplasmic Ca via the use of the Ca ionophore A-23187 or high extracellular K+ prevented or attenuated SNAP-induced dephosphorylation. Both BAPTA and nifedipine also decreased DNA synthesis, providing further evidence to link dephosphorylation to antimitogenesis. Two of the proteins dephosphorylated by treatment of cells with NO or EGTA were identified as the focal adhesion proteins, cortactin and paxillin. These results indicate that NO-induced dephosphorylation of protein phosphotyrosine is mediated by reduction of cytoplasmic Ca and suggest that dephosphorylation of focal adhesion proteins may be of relevance to the antimitogenic effect of NO.

Animals↗
PubMed1998

Interleukin-1beta-converting enzyme-deficient mice resist central but not systemic endotoxin-induced anorexia.

Interleukin-1beta (IL-1beta) mediates many of the behavioral responses to infection and inflammation, and IL-1beta-converting enzyme (ICE) processes intracellular IL-1beta, leading to its maturation and secretion. Here we demonstrate that intracerebroventricular injections of lipopolysaccharide (LPS) produced a greater reduction in both food intake and food-motivated behavior in wild-type compared with ICE-deficient (ICE -/-) mice. This defect occurred although ICE -/- mice were able to fully respond to intracerebroventricular injections of IL-1beta. In contrast, ICE -/- mice remained fully responsive to intraperitoneal injections of LPS. These results indicate that brain, but not peripheral, IL-1beta plays a critical role in the depression in food intake that occurs during inflammation.

Animals↗
PubMed1998

Three-dimensional ultrasound study of carotid arteries before and after endarterectomy; analysis of stenotic lesions and surgical impact on the vessel.

BACKGROUND AND PURPOSE: It has been proved that symptomatic patients with severe carotid stenosis benefit from endarterectomy. Currently used methods for quantitation of the severity of carotid stenosis have limitations, and the impact of endarterectomy on the operated region of carotid artery remains unknown. The purpose of this study was to examine the accuracy of a 3-D ultrasound system for quantitation of stenotic lesions and to evaluate changes in regional vessel volume and cross-sectional area after carotid endarterectomy. METHODS: We studied 14 patients with both carotid angiography and 3-D ultrasound. Of 13 patients who underwent surgery, 12 were reexamined with 3-D ultrasound after surgery. The length and volume of 20 randomly selected plaques were measured from 3-D data sets. The severity of stenosis was quantified by 3-D ultrasound using both a diameter method and an area method on cross-sectional views at the most stenotic site; the results were then compared with those from carotid angiography. The segmental vessel volume and average cross-sectional area of the operated artery both before and after endarterectomy were measured from 3-D ultrasound data. RESULTS: Good correlation was obtained between 3-D ultrasound and carotid angiography in quantitative analysis of carotid stenosis (SEE=12.4%, r=0.76, and mean difference=7.0+/-12.3% with the diameter method; SEE=10.5%, r=0.82, and mean difference=1.8+/-10.5% with the area method by 3-D ultrasound). 3-D ultrasound had excellent reproducibility and small intraobserver and interobserver variability in plaque length and volume measurements. No significant changes in segmental vessel volume and average cross-sectional area of the operated artery were observed after surgery in patients with suture closure. However, a significant increase in segmental vessel volume was obtained in patients with polyfluorethylene patches applied to the surgical opening of the artery. CONCLUSIONS: 3-D ultrasound can be used for both qualitative and quantitative analysis of plaques in the carotid artery and to detect and quantify significant carotid stenosis. Its volumetric potential has important clinical implications in serial follow-up studies for observing the progression or regression of stenotic lesions and for evaluating the outcome of interventional procedures such as endarterectomy or stent placement.

Adult↗
PubMed1998

Lef1 transcription factor expression defines airway progenitor cell targets for in utero gene therapy of submucosal gland in cystic fibrosis.

Cystic fibrosis (CF) has emerged as a paradigm disorder for assessing the utility of gene therapy in the treatment of genetic diseases. It is hypothesized that submucosal glands may play an important role in the pathophysiology of CF lung disease. However, this region poses several significant obstacles for gene therapy due to its inaccessibility from the lumen of adult proximal airways. In utero gene therapy to correct submucosal gland dysfunction in CF provides an attractive alternative strategy to target gland progenitor cells prior to gland formation and morphogenesis. Such approaches will require the use of integrating vectors capable of transducing expanding stem-cell/progenitor-cell populations in the lung. We described a newborn-ferret model of the proximal airway which was used to evaluate the phenotypic characteristics of submucosal gland progenitors and to test gene therapy strategies for targeting these cell types. To this end, we have isolated the ferret cDNA to the lymphoid enhancing factor 1 (Lef1) and have demonstrated that its mRNA expression specifically defines a subset of surface airway epithelial progenitor cells involved in the formation of primordial submucosal gland buds and subsequent gland morphogenesis. Such findings suggest that the transcriptional switch regulating activation of Lef1 expression defines the phenotype of early submucosal gland progenitor cells. In an effort to prove the principle of gene targeting to this progenitor-cell population, we evaluated the efficiency of recombinant retroviral vectors to target submucosal glands in a xenograft model system. Findings from these studies demonstrated successful gene targeting to progenitor cells of submucosal gland buds which was stable throughout subsequent gland development. In summary, these studies have provided evidence for the existence of phenotypically distinct submucosal gland progenitor cells which represent appropriate targets for gene therapy of submucosal glands in CF.

Amino Acid Sequence↗
PubMed1998

Bovine ornithine decarboxylase gene: cloning, structure and polymorphisms.

Bovine ornithine decarboxylase (ODC) genomic clones were isolated from a bacteriophage lambda DASH genomic library. A total of 9452 bp sequence was determined which covers the entire sequence of the bovine ODC gene. Sequence analysis showed that the bovine ODC gene consisted of 12 exons which encode a protein identical to that inferred from a bovine ODC cDNA. Comparison of the structure and nucleotide sequence of the bovine, human and mouse ODC genes revealed that the gene was highly conserved. Primer extension analysis demonstrated that the transcription start point of bovine ODC mRNA was located 378 bp upstream from the A residue in the translation initiation codon. The 5'-untranslated region (UTR) of ODC mRNA was highly G + C rich, particularly in its 5'-most portion, and computer predictions suggested a very stable secondary structure for this region, with an overall free energy of formation of -134.4 kcal/mol. Conserved sequences and potential promoter elements including a TATA box, a possible CCAAT element, SP1 ranscription factor binding sites (GC boxes) and cAMP response elements (CRE) were identified in the 5'-flanking region of the gene. Two polymorphic restriction sites, a TaqI and a MspI, were mapped to the ODC gene and PCR-based methods for detection of the 2 polymorphisms were developed.

5' Untranslated Regions↗
PubMed1998

Sp1 and related factors fail to interact with the NF-kappaB-proximal G/C box in the LTR of a replication competent, brain-derived strain of HIV-1 (YU-2).

The HIV-1 LTR promoter proximal G/C box array has been demonstrated to function by interacting with the Sp1 transcription factor family whose members can act as either activators or repressors of transcription. In this regard, we have examined the interaction of the HIV-1 Sp binding sites with nuclear factors that are present in cell types that support HIV-1 replication, including those of lymphocytic, monocytic, and astrocytic origin. As determined by electrophoretic mobility shift (EMS) competition analyses using oligonucleotides containing the sequences of each of the Sp1 sites of HIV-1 strain LAI, the NF-kappaB-proximal Sp site (site III) displayed the highest binding activity compared to sites I and II with regard to Sp1 and related factors present in lymphocytic (Jurkat) and astrocytic (U-373 MG) nuclear extracts. Sp1 and two Sp3 isoforms were detected as the primary cellular constituents of DNA-protein complexes formed with the NF-kappaB-proximal site. Only modest differences in Sp1:Sp3 binding ratios were observed when this site was reacted with either astrocytic or lymphocytic nuclear extract. However, when nuclear extracts derived from two monocytic cell types that differ in the degree of differentiation were reacted with the HIV-1 LAI Sp site III, a large difference in Sp1 and Sp3 binding was observed. To determine if naturally occurring and replication-competent strains of HIV-1 contain base pair alterations within the Sp elements that affect the ability of the site to interact with Sp1 and related factors, a series of Sp site III variants were constructed and examined by EMS analyses. One of these sites, obtained from the published sequence of the YU-2 strain (a brain-derived macrophage tropic strain of HIV-1), displayed almost no Sp1 or Sp3 binding activity as a result of a single base pair alteration in Sp site III. This base-pair alteration, when placed in the context of an HIV-1 LAI LTR-luciferase construct, resulted in a 40-50% reduction in LTR activity in transiently transfected Jurkat and U-373 MG cells. Overall, these results suggest that specific G/C box sequence alterations present in the brain-derived HIV-1 variant YU-2, or possibly other brain-derived variants, may exhibit altered replication properties as a result of the low affinity of the NF-kappaB-proximal G/C box for members of the Sp transcription factor family.

Astrocytes↗
PubMed1998

[Intracardiac operations performed in beating heart through mini-thoracotomy in 34 patients].

OBJECTIVE: To introduce the technique of intracardiac operations performed in beating heart through mini-thoracotomy. METHOD: >From March 1995 to June 1997, intracardiac operations were performed in beating heart through right subaxillary anterolateral mini-thoracotomy with normothermic extracorporeal circulation in 34 patients. 16 patients had atrial septal defect, 14 ventricular septal defect, 2 mitral insufficiency, 1 right coronary artery-right ventricular fistula, and 1 Ebstein's anomaly. RESULT: The mean cardiopulmonary bypass time was 22.54 minutes. There were no embolism, arrhythmia and cerebral complications. Postoperative hospital stay was 8.0 +/- 2.2 days. All the patients had no heart murmur and residual shunt, and enjoyed a full range of physical activities in a follow-up of 2 to 26 months. CONCLUSION: Intracardiac operations performed in beating heart through right subaxillary anterolateral mini-thoracotomy appears to be less invasive, simple, safe and cosmetic.

Adolescent↗
PubMed1998

[Determination of polyamines in pyronaridine-sensitive and -resistant Plasmodium berghei-infected erythrocytes].

AIM: To understand the relationship between polyamine metabolism and pyronaridine resistance of malaria parasites. METHODS: Kunming strain mice weighing 18 g-22 g were inoculated intraperitoneally with Plasmodium berghei ANKA strain (pyronaridine-sensitive, PS), and P. berghei ANKA strain low and high pyronaridine resistant lines (PRA and PRB), respectively. Seven days after inoculation, blood samples were collected and WBC in the blood were removed by the method of chromatography using SE-cellulose and Sephadex G25 (1:2). After thin layer chromatography, the contents of three polyamines, i.e. putrescine(PTC), spermidine (SPD), and spermine(SPM) in normal and infected erythrocytes were determined with fluorescence spectrometer. The changes of polyamine level in PS and PRB infected erythrocytes of mice treated by a single oral dose of PND 5 and 10 mg/kg respectively were also observed. RESULTS: The contents of PTC, SPD and SPM in PS infected erythrocytes were 47.5 +/- 28.6, 97.7 +/- 34.0 and 81.7 +/- 23.8 nmol/10(9) RBC (n = 9), respectively, being 1.5, 3.5, and 6.6 times of those appeared in the normal RBC (32.0 +/- 9.9, 28.2 +/- 12.3, and 12.4 +/- 15.0 nmol/10(9) RBC, n = 9), respectively. The differences between two groups were significant. Interestingly, when mice infected with pyronaridine resistant line PRA and PRB, the contents of PTC, SPD and SPM in the infected erythrocytes increased to 187.7 +/- 139.9, 258.3 +/- 137.9 and 142.8 +/- 143.8 nmol/10(9) RBC (n = 18), and 345.5 +/- 223.0, 435.8 +/- 265.4 and 189.4 +/- 171.7 noml/10(9) RBC, respectively. Except for SPM, PTC and SPD in the PRA and PRB infected erythrocytes were significantly higher than those in the PS and PRA infected erythrocytes, respectively, being 3.9, 2.6 and 1.8, 1.7 times of those appeared in PS and PRA infected erythrocytes. In PND treated group, SPD and SPM contents of PS infected erythrocytes were decreased by 31.6% and 47.3% compared with non-treated group, but the polyamine level of PRB infected erythrocytes did not significantly change after PND administration. CONCLUSION: The resistance of P. berghei to PND is related to the alteration of polyamine metabolism in the malarial parasites.

Animals↗
PubMed1998

[A 5-year follow-up study of antiviral effect of interferon in patients with chronic hepatitis C].

In order to discuss the anti-viral effects of IFN alpha-2a and IFN alpha-2b on chronic hepatitis C in a short and long period of time after treatment, 70 cases of chronic hepatitis C treated with IFN alpha-2a, 46 cases with IFN alpha-2b and 28 cases as controls had been investigated in this study. The follow-up time began from half to 5 years. The serum negative conversion rate of HCV RNA and the normalization of serum alanine transaminase(ALT) were detected at the end of treatment and up to 5 years after therapy. The negative seroconversion rate of HCV RNA and the serum ALT normalization were 67.14% and 70.00% respectively in IFN alpha-2a group and 69.56%, 71.71% respectively in IFN alpha-2b group at the end of the treatment. After 5-year follow-up, the above two Indexes were 35.71%, 47.14% respectively in IFN alpha-2a group, and 39.13%, 52.17% respectively in IFN alpha-2b group. The effectiveness in treated patients was higher than that of controls (P < 0.01 and P < 0.05). Recombinant IFN alpha-2a and IFN alpha-2b are effective medicines for HCV infection. And interferon therapy had a high short-term complete response but a low long-term complete response in the treatment of chronic hepatitis C. HCV genotype seems to be an important factor in determining the response rate of IFN treatment in patients with chronic hepatitis C.

Adolescent↗
PubMed1998

[The research fields and advances of biomedical engineering].

The research fields and advances of biomedical engineering have been reviewed in four aspects, biomedical material, biomedical engineering appliance, tele-diagnostic system and biomedical recovery engineering with 14 references.

Biocompatible Materials↗
PubMed1998

[Studies on target localization of Parkinson's disease treated with gamma knife].

Ninety cases of Parkinson's disease were treated in our center from Dec. 1993 to Aug. 1997. Based on our work, we have developed a method for the MR localization in the treatment of Parkinson's disease with Gamma knife, including the fixing of stereotactic frame, the selection of target, and the correction of the target's coordinates. In this paper, the effects of fixing of coordinate frame on the localization of target have been analyzed. Also presented are the errors of the coordinates of the selected targets, compared with those corrected. The method reflects a new idea for target localization.

Algorithms↗
PubMed1998

[Determination of selenium by platform graphite furnace atomic absorption spectrometry].

The matrix modifier and its amount, the ashing or atomization temperature of selenium and interference experiment are investigated. The experimental result shows that the application of Pd-Ca as mixed matrix modifier not only reduces interference but also enhances ashing temperature and increases sensitivity. The method can be used directly for the determination of selenium in cereal by platform graphite furnace atomic absorption. The characteristic mass is 39 ng,the detection limit is 0.11 microg/g, the relative standard deviation is 4.9-7.7% and the recovery is 92-100%.

Graphite↗
PubMed1998

Infrequent mutation of the p16/MTS1 gene and overexpression of cyclin-dependent kinase 4 in human primary soft-tissue sarcoma.

The pl6INK4a/MTS1 (p16) gene encodes a specific inhibitor of cyclin-dependent kinase (CDK)4 and CDK6. The p16 gene is frequently mutated or deleted in many types of cancer cell lines as well as in certain types of primary tumors. p16 knockout mice are viable but predisposed to sarcoma and B-cell lymphoma. To investigate the role of p16 in human soft-tissue sarcoma tumor progression, we examined the p16 gene by Southern blot analysis and PCR sequencing in 30 pairs of primary soft-tissue sarcomas and autologous normal tissue. Only one tumor sample showed possible rearrangement of the p16 gene. In contrast, Western blot analysis of the p16 protein in 20 pairs of samples showed decreased p16 expression in only 20% of the tumors but elevated p16 expression in 40% of the tumors when compared with the autologous normal controls. Overexpression of p16 was not concomitant with loss of the RB protein as is found in several other types of cancers, because more than one-half of the tumors with increased p16 expression also had high levels of RB protein. On the other hand, the p16 target protein CDK4 was overexpressed in at least 60% of the tumors. In the majority of cases, CDK4 overexpression accompanied elevated p16 and/or RB levels. Our results suggest that: (a) alteration of the p16 gene is infrequent in primary soft-tissue sarcoma; (b) Cdk4 may act as an oncogene in soft-tissue sarcoma; and (c) elevated p16 and RB levels might be the result of compensatory up-regulation of these proteins to counteract CDK4 overexpression in these tumors. Our results also suggest that it is more informative to examine aberrations in the "p16-CDK4/cyclin D-RB" pathway than to selectively examine individual components in this pathway when investigating genetic changes involved in human malignancy.

Animals↗
PubMed1998

[ECG anomalies and axis deviations in heart transplant recipients: MRI studies].

The electrocardiogram is often abnormal after orthotopic cardiac transplantation. This study was conducted in order to evaluate the frequency of these abnormalities in a population of 29 patients transplanted according to the conventional mode or the total mode. We also investigated the correlation between these abnormalities and the presence of left ventricular hypertrophy or deviation of the left ventricular long axis. The left ventricular mass was measured by TM echocardiography. The position of the left ventricular long axis was determined by MR on a ultrarapid sequence. The ECG was normal in 5 patients. The abnormalities revealed in the other 24 patients were: an rSr' or rsr' appearance in V1 with a QRS complex less than 0.12 sec in 11 patients, complete right block in 1 patients, repolarization abnormalities (apart from those associated with branch blocks) in 8 patients, left axis deviation of the QRS in 5 patients, a biphasic P wave in V1 with a Morris index greater than 4 mV.sec in 5 patients, and double atrial activity in 3 patients. These abnormalities were observed regardless of the type of transplantation, with the exception of double atrial activity which was only observed in the group of patients undergoing conventional transplantation. On average, the long axis of the left ventricle was more horizontal and deviated to the left compared to age- and sex-matched controls. All patients with left axis deviation of the QRS had left ventricular hypertrophy versus 13 of the 24 patients without QRS axis deviation and abnormalities of position of the anatomical left ventricular long axis. Our results therefore suggest that the frequent presence of right branch block in heart transplant recipients is due to factors other than the position of the heart in the thorax, for example right ventricular hypertrophy.

Adult↗