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Biomedical subjects

J Yao

Publications and source records attributed to J Yao.

At least 109 records · Page 6Linked to original sources
PubMed2000

Identification of viable myocardium by perfusion imaging with intravenous contrast echocardiography after acute myocardial infarction.

Myocardial perfusion contrast echocardiography is evolving into an effective method for the evaluation of myocardial blood flow after acute coronary events. The direct injection of ultrasound contrast agents into the aortic and coronary circulation has been shown to accurately identify areas of viable myocardial tissue. Recently, intravenous ultrasound contrast has been found to be useful in detecting microvascular blood flow after the restoration of blood flow in patients with myocardial infarction. We present the case of a patient in whom intravenous ultrasound contrast assisted in the detection of viable myocardial tissue after an acute ischemic syndrome.

Aged↗
PubMed2000

Mitral regurgitation: comprehensive assessment by echocardiography.

Two-dimensional and Doppler echocardiography have become the major modalities for the assessment of mitral regurgitation. The combined use of these techniques provides information regarding the morphology of the valvular apparatus as well as the severity of regurgitation. Transesophageal and three-dimensional echocardiography provide a more-detailed evaluation of valve morphology, which can be valuable in determining suitability for valve repair. In patients with severe mitral regurgitation, echocardiographic assessment of ventricular size and function plays a critical role in determining the optimal timing of surgery.

Echocardiography↗
PubMed2000

Rubella virus nonstructural protein protease domains involved in trans- and cis-cleavage activities.

Rubella virus (RV) genomic RNA contains two large open reading frames (ORFs): a 5'-proximal ORF encoding nonstructural proteins (NSPs) that function primarily in viral RNA replication and a 3'-proximal ORF encoding the viral structural proteins. Proteolytic processing of the RV NSP ORF translation product p200 is essential for viral replication. Processing of p200 to two mature products (p150 and p90) in the order NH(2)-p150-p90-COOH is carried out by an RV-encoded protease residing in the C-terminal region of p150. The RV nonstructural protease (NS-pro) belongs to a viral papain-like protease family that cleaves the polyprotein both in trans and in cis. A conserved X domain of unknown function was found from previous sequence analysis to be associated with NS-pro. To define the domains responsible for cis- and trans-cleavage activities and the function of the X domain in terms of protease activity, an in vitro translation system was employed. We demonstrated that the NSP region from residue 920 to 1296 is necessary for trans-cleavage activity. The domain from residue 920 to 1020 is not required for cis-cleavage activity. The X domain located between residues 834 and 940, outside the regions responsible for both cis- and trans-cleavage activities of NS-pro, was found to be important for NS-pro trans-cleavage activity but not for cis-cleavage activity. Analysis of sequence homology and secondary structure of the RV NS-pro catalytic region reveals a folding structure similar to that of papain.

Amino Acid Sequence↗
PubMed2000

Mutations in the E1 hydrophobic domain of rubella virus impair virus infectivity but not virus assembly.

Rubella virus (RV) virions contain three structural proteins, a capsid protein that interacts with viral genomic RNA to form a nucleocapsid and two membrane glycoproteins, E2 and E1. We found that substitution of either an aspartic acid residue at Gly93 (G93D) or a glycine residue at Pro104 (P104G) in the internal hydrophobic domain of E1 affected virus infectivity but not virus assembly. Viruses carrying G93D and P104G mutations had impaired infectivity, reduced 1,000-fold and 10-fold, respectively. A revertant was isolated from the G93D mutant. Sequencing analysis showed that the substituted aspartic acid residue in G93D mutant had reverted to the original glycine residue, suggesting the involvement of Gly93 in membrane fusion during viral entry.

Amino Acid Substitution↗
PubMed2000

A single-amino-acid substitution of a tyrosine residue in the rubella virus E1 cytoplasmic domain blocks virus release.

Rubella virus particles, consisting of a nucleocapsid surrounded by a lipid envelope in which two virus-encoded glycoproteins E1 and E2 are embedded, assemble on intracellular membranes and are secreted from cells, possibly via the cellular secretory pathway. We have recently demonstrated that the cytoplasmic domain of E1 (residues 469 to 481, KCLYYLRGAIAPR) is required for virus release. Alteration of cysteine 470 to alanine did not affect virus release, whereas mutation of leucine 471 to alanine reduced virus production by 90%. In the present study, substitutions of remaining amino acids in the E1 cytoplasmic domain were made in order to investigate the role of each amino acid in regulating rubella virus release. Generated mutants were analyzed in the context of infectious full-length cDNA clone and virus-like particles using combined genetic, biochemical, and electron microscopic approaches. Substitution of a single residue of tyrosine 472 to alanine or tyrosine 473 to serine resulted in a block in virus release without affecting protein transport and virus budding into the lumen of the Golgi complexes. Infectious RNA transcripts bearing these mutations were incapable of forming plaques. Mutants with substitutions at the amino-terminal region (leucine 474, arginine 475, and glycine 476) in the E1 cytoplasmic domain had reduced virus release and small-plaque phenotype, while mutants with substitutions at the carboxy-terminal region (alanine 477, isoleucine 478, alanine 479, proline 480, and arginine 481) had only marginal defects in virus release. Plaque-forming revertants could be isolated from mutants Y472A and Y473S. Sequencing analysis revealed that the substituted serine residue in mutant Y473S reverted to the original tyrosine residue, whereas the substituted alanine residue in mutant Y472A was retained. These results indicate that the E1 cytoplasmic domain modulates virus release in a sequence-dependent manner and that the tyrosine residues are critical for this function. We postulate that residues YYLRG constitute a domain in the E1 tail that may interact with other proteins and this interaction is involved in regulating virus release.

Amino Acid Sequence↗
PubMed2000

Osmotic threshold and sensitivity for vasopressin release and fos expression by hypertonic NaCl in ovine fetus.

In adults, hyperosmolality stimulates central osmoreceptors, resulting in arginine vasopressin (AVP) secretion. Near-term fetal sheep have also developed mechanisms to respond to intravascular hypertonicity with stimulation of in utero AVP release. However, prior studies demonstrating fetal AVP secretion have utilized plasma tonicity changes greater than those required for adult osmotically induced AVP stimulation. We sought to examine near-term fetal plasma osmolality threshold and sensitivity for stimulation of AVP secretion and to correlate plasma hormone levels with central neuronal responsiveness. Chronically instrumented ovine fetuses (130 +/- 2 days) and maternal ewes simultaneously received either isotonic or hypertonic intravascular NaCl infusions. Maternal and fetal plasma AVP and angiotensin II (ANG II) levels were examined at progressively increasing levels of plasma hypertonicity. Intravenous hypertonic NaCl gradually elevated plasma osmolality and sodium levels. Both maternal and fetal plasma AVP increased during hypertonicity, whereas ANG II levels were not changed. Maternal AVP levels significantly increased with a 3% increase in plasma osmolality, whereas fetal plasma AVP significantly increased only at higher plasma osmolality levels (over 6%). Thus the slope of the regression of AVP vs. osmolality was greater for ewes than for fetuses (0.232 vs. 0.064), despite similar maternal and fetal plasma osmolality thresholds for AVP secretion (302 vs. 304 mosmol/kg). Hyperosmolality induced Fos immunoreactivity (FOS-ir) in the circumventricular organs of the fetal brain. FOS-ir was also demonstrated in the fetal supraoptic and paraventricular nuclei (SON and PVN), and double labeling demonstrated that AVP-containing neurons in the SON and PVN expressed Fos in response to intravenous NaCl. These results demonstrate that, in the ovine fetus at 130 days of gestation, neuroendocrine responses to cellular dehydration are functional, although they evidence a relatively reduced sensitivity for AVP secretion compared with the adult.

Age Factors↗
PubMed2000

Gene transfer of recombinant endothelial nitric oxide synthase to liver in vivo and in vitro.

Endothelial nitric oxide synthase (eNOS)-derived nitric oxide (NO) contributes to hepatic vascular homeostasis. The aim of this study was to examine whether delivery of an adenoviral vector encoding eNOS gene to liver affects vasomotor function in vivo and the mechanism of NO production in vitro. Rats were administered adenoviruses encoding beta-galactosidase (AdCMVLacZ) or eNOS (AdCMVeNOS) via tail vein injection and studied 1 wk later. In animals transduced with AdCMVLacZ, beta-galactosidase activity was increased in the liver, most prominently in hepatocytes. In AdCMVeNOS-transduced animals, eNOS protein levels and catalytic activity were significantly increased. Overexpression of eNOS diminished baseline perfusion pressure and constriction in response to the alpha(1)-agonist methoxamine in the perfused liver. Transduction of cultured hepatocytes with AdCMVeNOS resulted in the targeting of recombinant eNOS to a perinuclear distribution and binding with the NOS-activating protein heat shock protein 90. These events were associated with increased ionomycin-stimulated NO release. In summary, this is the first study to demonstrate successful delivery of the recombinant eNOS gene to liver in vivo and in vitro with ensuing NO production.

Adenoviridae↗
PubMed2000

Human tau filaments induce microtubule and synapse loss in an in vivo model of neurofibrillary degenerative disease.

The intracellular accumulation of tau protein and its aggregation into filamentous deposits is the intracellular hallmark of neurofibrillary degenerative diseases such as Alzheimer's Disease and familial tauopathies in which tau is now thought to play a critical pathogenic role. Until very recently, the lack of a cellular model in which human tau filaments can be experimentally generated has prevented direct investigation of the causes and consequences of tau filament formation in vivo. In this study, we show that human tau filaments formed in lamprey central neurons (ABCs) that chronically overexpress human tau resemble the 'straight filaments' seen in Alzheimer's Disease and other neurofibrillary conditions, and are distinguishable from neurofilaments by their ultrastructure, distribution and intracellular behavior. We also show that tau filament formation in ABCs is associated with a distinctive pattern of dendritic degeneration that closely resembles the cytopathology of human neurofibrillary degenerative disease. This pattern includes localized cytoskeletal disruption and aggregation of membranous organelles, distal dendritic beading, and the progressive loss of dendritic microtubules and synapses. These results suggest that tau filament formation may be responsible for many key cytopathological features of neurofibrillary degeneration, possibly via the loss of microtubule based intracellular transport.

Alzheimer Disease↗
PubMed2000

[The relationship between the levels of serum fibrosis marks and morphometric quantitative measurement of hepatic histological fibrosis].

OBJECTIVE: To study the relationship between the levels of serum fibrosis marks hyaluronic acid (HA), procollagen type III (PCIII), collagen type IV (CIV) and the degree of hepatic fibrosis, and the clinical significance of HA, PCIII, CIV in the diagnosis of hepatic fibrosis to the chronic viral hepatitis. METHODS: The concentrations of serum HA, PCIII, CIV in 151 patients with chronic viral hepatitis were measured by radioimmunoassay. Liver biopsies were performed in all of the patients at the same time. Morphometric quantitative measurements of hepatic fibrosis were performed in 4mum sections stained with masson stain using a fully automated image-analysis system. RESULTS: The levels of serum HA, PCIII, CIV were all increased steadily with the progression of hepatic fibrosis, and the highest levels were in stage 4. They were all positively correlated with staging of the liver pathology and morphometric measurement of hepatic fibrosis (P<0.001). The coefficient value (r) with staging were 0.694, 0.493, 0.552 (P<0.001), respectively and with morphometric measurement of hepatic fibrosis were 0.715, 0.596, 0.537 (P<0.001), respectively. CONCLUSION: The levels of serum HA, PCIII, CIV are in concert with the degree of hepatic fibrosis, and the determination of these marks may be valuable for diagnosing hepatic fibrosis.

Adolescent↗
PubMed2000

[Apoptosis and uterine cervical carcinogenesis].

OBJECTIVE: To investigate the possible role of apoptosis in the development of uterine cervical carcinoma. METHODS: Formalin-fixed, paraffin-embedded samples from 190 patients [41 patients with severe dysplasia (SD); 37 with carcinoma in situ(CIS); 31 with microinvasive carcinoma (MIC), 40 with fran invasive large cell non-keratinizing epidermoid carcinoma (IC)], and 41 samples from normal cervical squamous epithelium (NE) were studied. The number of apoptotic cells was assessed in situ by the TDT-mediated dUTP-biotin nick end labeling (TUNEL) method. PCNA, p53 and bcl-2 were demonstrated immunohistochemically. RESULTS: (1) In NE, TUNEL-positive cells were found in the superficial layer and PCNA-positive cells were confined in the lamina profunda, while in cervical neoplasia these cells were irregulasly scattered throughout the cervical lesions. (2) The TUNEL staining index decreased while PCNA increased with progression of the neoplasm, showing a significant negative correlation between apoptosis and proliferation. (3) In patients with SD and CIS who had overexpression of p53 and bcl-2 proteins, the cells positively stained by TUNEL were significantly less in number than in these with negative p53 and bcl-2 expression. No such observation for PCNA expression. CONCLUSION: These results suggest that apoptosis is associated with the early process of cervical carcinogenesis and apoptosis is closely correlated with overexpression of p53 and bcl-2 proteins.

Apoptosis↗
PubMed2000

[Expression of Epstein-Barr virus latent membrane protein 2 in murine fibroblasts by retroviral-mediated gene transfer].

OBJECTIVE: This study is to find an efficient way to express EB virus latent membrane protein 2 in mammalian cells, and provide for further investigate on the function of LMP2 protein and its role in cellular immunity. METHODS: The LMP2 gene was cloned into the EcoR I site of a retroviral vector LXSN and the recombinant LXSN-LMP2 was transfected into PT67 by lipofect TAMINE. After screened by G418, the supernatant of G418-resistant cells was used to infect murine fibroblasts NIH 3T3 to determine the virus titer. DNA was extracted from transfected cells and tested by PCR. Indirect immunofluorescence assay was used to detect the expression of the inserted gene. RESULTS: The virus titer was 5.8 x 10(5) PFU/ml. The result of PCR showed that the LMP2 gene had been integrated into the DNA of transfected cells. Indirect immunofluorescence showed that the LMP2 gene had been expressed in the murine fibroblasts. CONCLUSIONS: EB virus LMP2 gene had been integrated into the genome of cells by retroviral-mediated transfer and the target gene had been expressed.

3T3 Cells↗
PubMed2000

[The second dorsal metacarpal artery flap with distant pivot point].

OBJECTIVE: To introduce a modified flap pedicled with the second dorsal metacarpal artery. METHOD: Seven thumb wounds were repaired with the second dorsal metacarpal artery flap. The size of the flap ranged from 1 cm x 3 cm to 2 cm x 4 cm, and the length of the vascular pedicle was 6 to 7 cm. RESULT: All flaps survived and the results were satisfactory. CONCLUSION: This method is an option for repairing thumb defects when the local skin flap or island flap on the index and middle finger is not available.

Adolescent↗
PubMed2000

[Precise determine the position of the opposite upper lid after correcting the congenital unilateral ptosis and their relationship].

OBJECTIVE: The good results should be obtained after correction of the congenital unilateral ptosis for bilateral eyes. METHODS: A formula was made and determined the position of the opposite upper lid according to Hering's law. RESULTS: Thirty-two patients with congenital unilateral ptosis were operated. The correct rate is 94.12% according to the formula and the control is 66.67%. CONCLUSION: The position of the opposite upper lid should be determined after the ptosis eye corrected before operation in order to obtain a good results.

Adolescent↗
PubMed2000

[Reconstructing the limb end defects with a free mini-flap, a report of 18 cases].

OBJECTIVE: Some operative procedures were introduced for repairing hand or foot defects using the free mini-flap from the finger or toe. METHODS: Eighteen cases of finger tip or foot wound were treated with the free mini-flap and vessel anastomosis. The size of the flap was 2 cm x 1 cm to 6 cm x 4 cm and the length of the pedicle was 2 to 4 cm. RESULTS: All the eighteen free mini-flaps survived and the results were satisfactory. CONCLUSION: The method of the mini-flap is a good option for covering of thumb, finger or foot defects when a local or an island flap is not available.

Adolescent↗
PubMed2000

[Further survey on efficacy of attenuated live hepatitis A vaccines].

OBJECTIVE: To further survey the protective efficacy of the standard attenuated live hepatitis A vaccines (H(2) strain). METHODS: Randomized and controlled trials were performed in Fucheng county, Hebei province. A total of 12 036 children were assigned into vaccine group (5 551) and control group (6 485) by cluster sampling. The morbidity of hepatitis A was observed and the blood was collected once hepatitis A showed epidemic to detect anti-HAV IgG and IgM. RESULTS: During the period of the first 7 months after vaccination, hepatitis A was sporadic, the morbidity of hepatitis A was 0.55/100 000, and only 1 case occurred in the control group and no case in the vaccine group. From January to August 1998, hepatitis A showed epidemic in a township of this county. The morbidities were 0.37% and 6.69% for vaccine group and control group, respectively. The protective efficacy of the vaccine was 94.47%. The ratios of clinical cases to subclinical infections were 1 to 11 and 1 to 1 for vaccine and control groups, respectively (P < 0.05). CONCLUSION: The H(2) strain vaccine has a very good protective efficacy, and obviously decreases the attack rate, new infection rate and clinical cases by HAV infection.

Child↗
PubMed2000

[Protective efficacy of H2 strain live attenuated hepatitis A vaccines in an outbreak of hepatitis A].

OBJECTIVE: To investigate the protective efficacy of H(2) strain live attenuated hepatitis A vaccine (H(2)-strain vaccine) locally produced in an outbreak of hepatitis A (HA). METHODS: A nonrandomized controlled design was used in a trial for HA vaccination. Five thousand five hundred and fifty-one children at preschool classes and at grades 1 - 3 of primary schools were selected in 14 villages. Epidemiological and serological methods were used to evaluate its protective efficacy of the vaccines and serum immunoglobulin M against hepatitis A virus (IgM anti-HAV) was detected with ELISA for 271 subjects in vaccinated group and 341 in the control one. RESULTS: An outbreak of HA occurred one year after the vaccination with 26 cases in the vaccinated group, including one vaccine-related case with an attack rate of 0.28% (1/356), and 25 cases in the control group with an attack rate of 5.92% (25/422). The protective efficacy of vaccines was 95.27% (95% confidence interval of 85.83% to 104.72%). Positivity of IgM anti-HAV, i.e., newly-infected cases, was 4.43% (12/271) in the vaccinated group and 13.38% (42/314) in the control group, respectively. Clinically apparent cases accounted for 8.33% (1/12) and 50.00% (21/42) in newly-infected cases in vaccinated and control groups, respectively. CONCLUSION: Vaccination with H(2) strain vaccines locally produced was effective in reducing occurrence of HA during its outbreak, but not so effective in preventing its infection. A booster dose of HA vaccine should be vaccinated for children in adequate time.

Adolescent↗
PubMed2000

[Two-dimensional surface Raman imaging of a roughened iron electrode in saline solution].

By using a confocal microprobe Raman system and proper surface roughening procedure for iron, the pit corrosion behavior of bare iron electrode in 3.4% NaCl (saline solution) solution has been investigated. The surface-enhanced Raman scattering (SERS) spectra of the corrosion products due to the pit corrosion at positive potential was obtained with high ratio of signal to noise. The application of SERS technique has been extended successfully to the study of iron corrosion. The two-dimensional surface Raman imaging acquired at 660 cm-1 was obtained also with the utility of surface Raman image technique. Results show that different iron oxides should coexist in the pit corrosion region and the distribution of the corrosion products was not uniform.

Chemical Phenomena↗