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Biomedical subjects

Y Bao

Publications and source records attributed to Y Bao.

At least 73 records · Page 4Linked to original sources
PubMed1998

Mapping of RNA accessible sites for antisense experiments with oligonucleotide libraries.

Antisense experiments are often complicated by the lack of reliable methods for selecting effective antisense sequences. Chimeric oligodeoxynucleotide (ODN) libraries and ribonuclease H (RNase H) were used to identify regions on the 1253 nucleotide angiotensin type-1 receptor (AT1) mRNA that are accessible to hybridization with antisense ODNs. Phosphorothioate antisense ODNs targeted against accessible sites reduced AT1 receptor levels by at least 50% in cell culture. ODNs to 4 sites produced a 70% to 80% reduction. In contrast, most sequences targeted between accessible sites were ineffective. When injected into the brains of rats, ODNs targeted to accessible sites reduced AT1 (by 65%) but not AT2 receptor levels. Additionally, AT1 receptor function as measured by agonist-induced water intake, was significantly attenuated in these rats. ODNs directed between accessible sites were ineffective at suppressing water intake. RNA mapping can be applied to any RNA target to facilitate selection of multiple, active antisense sequences for cell culture and in vivo experiments.

Animals↗
PubMed1998

Developmental regulation of intercellular protein trafficking through plasmodesmata in tobacco leaf epidermis

Plasmodesmata mediate direct cell-to-cell communication in plants. One of their significant features is that primary plasmodesmata formed at the time of cytokinesis often undergo structural modifications, by the de novo addition of cytoplasmic strands across cell walls, to become complex secondary plasmodesmata during plant development. Whether such modifications allow plasmodesmata to gain special transport functions has been an outstanding issue in plant biology. Here we present data showing that the cucumber mosaic virus 3a movement protein (MP):green fluorescent protein (GFP) fusion was not targeted to primary plasmodesmata in the epidermis of young or mature leaves in transgenic tobacco (Nicotiana tabacum) plants constitutively expressing the 3a:GFP fusion gene. Furthermore, the cucumber mosaic virus 3a MP:GFP fusion protein produced in planta by biolistic bombardment of the 3a:GFP fusion gene did not traffic between cells interconnected by primary plasmodesmata in the epidermis of a young leaf. In contrast, the 3a MP:GFP was targeted to complex secondary plasmodesmata and trafficked from cell to cell when a leaf reached a certain developmental stage. These data provide the first experimental evidence, to our knowledge, that primary and complex secondary plasmodesmata have different protein-trafficking functions and suggest that complex secondary plasmodesmata may be formed to traffic specific macromolecules that are important for certain stages of leaf development.

Journal Article↗
PubMed1998

Comparison of risk profile and outcomes in patients undergoing surgical and catheter-based revascularization.

BACKGROUND: The effects of the randomized revascularization trials and improved strategies and techniques for coronary artery bypass graft (CABG) surgery and percutaneous transluminal catheter-based revascularization (PTCR) on current patient selection and clinical outcomes are unknown. METHODS: We evaluated a concurrent, contemporary (1995 to 1997), and consecutive group of patients undergoing CABG (n = 982) or PTCR (n = 939) in a single institution that participated in the Bypass Angioplasty Revascularization Investigation (BARI) trial. Results are presented as percent or mean +/- SD. Compared to PTCR, patients undergoing CABG were older (66.2+/-10.7 vs. 62.0+/-11.8 years, p<0.05) with a higher incidence of hypertension (73.3% vs. 52.4%, p<0.05), diabetes (32.5% vs. 23.1%, p<0.05), active smoking (67.8% vs. 27.2%, p<0.05), prior myocardial infarction (MI)(66.8% vs. 28.5%, p<0.05), peripheral vascular disease (19.8% vs. 7.7%, p<0.05), prior cerebrovascular accident (CVA)/transient ischemic attack (TIA) (6.4% vs. 2.8%, p<0.05), and a lower ejection fraction (48.7%+/-14.5% vs. 55.3%+/-11.7%, p<0.05). The presenting functional class and incidence of female gender were similar for both revascularization strategies. RESULTS: Compared to patients undergoing CABG, those undergoing PTCR were more likely to have single or two vessel coronary artery disease (88.6% vs. 23.1%, p<0.001) and had fewer vessels revascularized per patient (1.08+/-0.30 vs. 3.5+/-0.98, p<0.001). Outcomes were comparable for CABG and PTCR with a similar incidence of death (1.0% vs. 0.9%, NS), renal insufficiency (0.7% vs. 0.6%, NS), and CVA/TIA (0.9% vs. 0.3%, NS). Patients undergoing CABG had a higher incidence of pulmonary complications (5.2% vs. 1.0%, p<0.05), a lower incidence of periprocedural MI (1.1% vs. 4.1%, p<0.05) and major complication (5.9% vs. 9.4%, p<0.05), but longer hospital stays (6.5+/-5.1 vs. 3.1+/-2.6 days, p<0.05). CONCLUSIONS: Despite higher clinical and angiographic risk profiles in patients undergoing CABG, clinical results, morbidity, and mortality were comparable to those of PTCR. With evolving techniques, continued reevaluation of indications and outcomes are necessary.

Aged↗
PubMed1998

Histological effects and predictive biomarkers of TPP induction chemotherapy for oral carcinoma.

The effects of an induction chemotherapy with THP-adriamycin, cisplatin, and peplomycin (TPP) were studied in 32 patients with operable oral cancer. The histological evaluation according to the Shimozato-Oboshi classification was Grade (G) IV in ten cases (31.3%), GIII in one case, and GIIb in four cases. Induction of apoptosis and differentiation-inducing effects, hyperkeratinization or bone formation, were observed in some cases. The overall clinical response rate and histological response rate were 63% and 47%, respectively. Grade III was obtained in seven metastatic lymph nodes of three patients. The expressions of PCNA, p53, and AgNORs before and after chemotherapy were studied. The prechemotherapeutic PCNA positive cell index (PI) of the highly responsive tumors (GIII, IV) was significantly lower than that of the poorly responsive tumors (G0-IIb) (P < 0.01). Similar results were obtained in the evaluation of p53 PI (P < 0.05), suggesting that PCNA and p53 are useful biomarkers for predicting the efficacy of TPP chemotherapy.

Antibiotics, Antineoplastic↗
PubMed1998

Polymorphism of DXS102 locus in Chinese population and its application to gene diagnosis in hemophilia B family.

OBJECTIVE: To establish the polymorphism of DXS102 locus from Xq26.3-27.1 in Chinese population for the gene diagnosis in Hemophilia B family. METHODS: DNA was extracted from blood samples obtained from Shanghai unrelated volunteer donors with phenol-chloroform method. A total of 23x chromosomes (154 from females, 80 from males) were studied. A hemophilia B family in which a hemophilia B patient has received gene therapy was analyzed. The polymorphism of DXS102 locus in Chinese population was determined with amplified fragment length polymorphisms assay (Amp-FLP), denaturing polyacrylamide gel electrophoresis, silver stain detection. Short tandem repeats (STRs) linkage analysis was used to conduct gene diagnosis in hemophilia B family. RESULTS: Eight alleles were found at DXS102 locus, of which two alleles were first reported. The repeated number of AC dinucleotide ranges from 13 to 21. And the values of the observed heterozygosity, calculated heterozygosity and polymorphism information content(PIC) were 0.87, 0.80, 0.80 respectively. It was also found that the difference of the allele frequencies of DXS102 in Chinese and European populations was significant. By using the linkage analysis of the DXS102 locus, a family with a hemophilia B patient receiving gene therapy in 1994 was analyzed and meanwhile a carrier in that family was then detected. CONCLUSIONS: The polymorphism of DXS102 locus reveals significant difference between Chinese and European populations. DXS102 locus can be used as a promising marker for gene diagnosis in hemophilia B family.

Alleles↗
PubMed1998

[Inquiry into the mechanism of long-acting bronchodilators].

OBJECTIVE: To compare the intrinsic activity and the affinity of long-(formoterol and salmeterol) and short-acting (fenoterol and salbutamol) bronchodilators with isoproterenol in membranes of calf tracheal smooth muscle. METHODS: Membranes were prepared after isolation of intact cells using a mixture of collagenase and pronase. Affinities were measured with radioligand binding. Intrinsic activities (IA) of agonists and effective concentrations of agonists used for half maximum stimulation of adenylate cyclase (AC) (EC50) were determined as stimulants of beta 2-adrenoceptor coupled AC activity using alpha-22P-ATP as substrate. RESULTS: The results showed that IA estimated as fraction of the maximum effect by isoproterenol (1.00) were 1.00, 0.76, 0.81 and 0.83 for formoterol, salmeterol, fenoterol and salbutamol respectively. Affinities measured as dissociation constants (pKD) exhibited higher affinities for long-acting (formoterol: 8.02, salmeterol: 8.43) than for short-acting agonists (fenoterol: 5.84, salbutamol: 5.84). Relative effects of agonists (pEC50) were much higher for formoterol (9.10) and salmeterol (8.70) than for fenoterol (6.69) and salbutamol (6.78). CONCLUSIONS: The results indicated that formoterol was characterized as a full agonist with a 20-fold higher affinity than isoproterenol whereas the other agonists acted as partial agonists. Significant amplifications of receptor signalling quantified as difference of values between pEC50 and pKD was found for the agonists in the tested receptor membranes. It is suggested that high IA, affinity and the signal amplification of formoterol might play a role in its long-acting effect.

Adrenergic beta-Agonists↗
PubMed1998

Glutathione transport in immortalized HLE cells and expression of transport in HLE cell poly(A)+ RNA-injected Xenopus laevis oocytes.

PURPOSE: To determine reduced glutathione (GSH) transport in cultured human lens epithelial cells (HLE-B3) and plasma membrane vesicles and to study the expression of GSH transport in Xenopus laevis oocytes injected with poly(A)+ RNA from HLE-B3 cells. METHODS: Confluent HLE-B3 cells pretreated with 10 mM DL-buthionine sulfoximine and 0.5 mM acivicin were used in GSH uptake studies. The uptake of 35S-GSH was performed for 30 minutes in either NaCl medium (Na+-containing) or choline chloride medium (Na+-free) at 37 degrees C and 4 degrees C. The molecular form of 35S uptake was determined by high-performance liquid chromatography. GSH uptake kinetics were studied in acivicin and buthionine sulfoximine-treated HLE-B3 cells in NaCl medium in the concentration range 0.01 microM to 50 mM. The transport of GSH and the effect of Na+ on uptake also were determined in mixed plasma membrane vesicles from HLE-B3 cells. In oocyte expression studies, HLE-B3 poly(A)+ RNA was injected into X. laevis oocytes and GSH uptake experiments were performed 3 days after injection. The uptake of 35S-GSH and GSH efflux rates were determined in HLE-B3 poly(A)+ RNA-injected oocytes. RESULTS: No significant difference was found in the uptake of 1 mM GSH+/-acivicin (17.7+/-4.3 versus 15.7+/-1.4 picomoles/min(-1) per 10(6) cells). However, GSH uptake was significantly lower in Na+-free medium compared with Na+-containing medium (10.3+/-0.7 versus 16.8+/-0.9 picomoles/min(-1) per 10(6) cells; P < 0.01). GSH uptake in NaCl medium was carrier mediated. GSH uptake showed partial sodium dependency from 5 microM to 5 mM GSH in mixed plasma membrane vesicles from HLE-B3 cells. Oocytes injected with HLE-B3 poly(A) RNA expressed uptake and efflux of GSH. Uptake showed partial Na+ dependency at various GSH concentrations. The efflux rates were approximately 30-fold higher than those in water-injected oocytes (0.48+/-0.03 versus 0.016+/-0.005 (nanomoles per hour(-1) per oocyte, respectively). The molecular form of uptake in cultured cells and in oocyte studies was predominantly as intact GSH. CONCLUSIONS: HLE-B3 cells and plasma membrane vesicles transported GSH by a carrier-mediated process. HLE-B3 poly(A)+ RNA injected X laevis oocytes expressed GSH transport. GSH uptake was partially Na+ dependent in all systems. HLE-B3 cells offer a useful model for characterizing GSH transport and for studying its regulatory role in the etiology of cataracts.

Animals↗
PubMed1998

Beneficial effects of angiotensin-converting enzyme inhibitors during acute revascularization.

BACKGROUND: This experimental study was undertaken to determine whether using angiotensin-converting enzyme inhibitors during surgical revascularization of acutely ischemic myocardium would improve wall motion and limit infarct size. METHODS: Twenty pigs underwent 90 minutes of occlusion of the second and third diagonal arteries followed by 45 minutes of cardioplegic arrest and 180 minutes of reperfusion. In 10 animals, the angiotensin-converting enzyme inhibitor enalaprilat (0.05 mg/kg) was infused intravenously during coronary occlusion; 10 other animals received no angiotensin-converting enzyme inhibitors. Ischemic damage was assessed by the number of cardioversions required for ventricular tachycardia or fibrillation; wall motion scores using echocardiography (4=normal to -1=dyskinesia); and infarct size using histochemical staining. Epicardial coronary artery vasomotor function was assessed using standard organ chamber methodology. RESULTS: Enalaprilat-treated hearts had the least amount of ventricular irritability (0.84+/-0.24 versus 2.77+/-0.22 cardioversions; p < 0.01), the best recovery of wall motion score (3.20+/-0.15 versus 1.52+/-0.07; p < 0.0001), and the lowest infarct size (22.6%+/-1.4% versus 37.7%+/-3.0%; p < 0.001). Endothelium-independent relaxation was preserved in all hearts; however, endothelium-dependent relaxation was impaired in both groups. CONCLUSIONS: Angiotensin-converting enzyme inhibitors reduce myocardial damage during surgical revascularization of acutely ischemic myocardium.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1997

Apoptosis of chondrocytes in transgenic mice lacking collagen II.

Previous work demonstrated that collagen fibrils were not detectable in the cartilage of transgenic mice homozygous for targeted inactivation of the collagen II gene. In the present work, we used the same mice to show that chondrocytes undergo apoptosis in the absence of collagen II, the major component of the extracellular matrix of cartilage. The chondrocytes in the homozygous mice had condensed nuclei, fragmentation of nuclear DNA, and decreased levels of the Bcl-2 protein. These results provide direct evidence that cartilage extracellular matrix lacking collagen II cannot support the survival of chondrocytes. In addition, the results suggest that apoptosis may play a role in degenerative connective tissue diseases such as osteoarthritis in which there is extensive tissue loss.

Animals↗
PubMed1997

Isolation and nucleotide sequence of human liver glycogen debranching enzyme mRNA: identification of multiple tissue-specific isoforms.

Glycogen storage disease type III (GSD-III) is caused by a deficiency of glycogen debranching enzyme (AGL) activity. Patients are found to have deficient AGL activity in both muscle and liver, and also enzyme deficiency in the liver, but not in muscle. To determine the molecular basis of enzymatic variability in GSD-III and to elucidate the mechanism for control of tissue-specific expression of AGL, we previously cloned and sequenced the human muscle AGL cDNA. Here we report the isolation and nucleotide sequence of liver AGL cDNA and the tissue distribution of the isoform mRNAs. The predominant form of human liver AGL cDNA (isoform 1) contained 400 bp of 5' untranslated region, 4596 bp of coding region, and 2371 bp of 3' untranslated region. The liver AGL mRNA sequence was identical to the previously published muscle sequence (isoform 5) for most of the length, except for the 5' end, in which the liver sequence diverged completely from the muscle sequence. The divergence began with the transcription start point and extended 82 nucleotides downstream from the translation initiation codon. Six isoforms of AGL mRNA were identified and sequenced from liver and muscle. These isoforms differed only at the 5' end. Tissue distribution studies showed that liver, kidney and lymphoblastoid cells expressed predominantly isoform 1; whereas muscle and heart expressed not only isoform 1, but also muscle-specific isoform mRNAs (isoforms 2, 3 and 4). Defining tissue-specific AGL isoform mRNAs is an important step toward understanding the molecular basis of enzymatic variability in GSD-III.

Amino Acid Sequence↗
PubMed1997

Reduction of thymine hydroperoxide by phospholipid hydroperoxide glutathione peroxidase and glutathione transferases.

Thymine hydroperoxide (5-hydroperoxymethyluracil), a model compound representing products of oxidative damage to DNA, is a substrate for glutathione peroxidase and some isoforms of glutathione transferase. In this paper, we show that selenium-dependent human phospholipid hydroperoxide glutathione peroxidase (Se-PHGPx) exhibits about four orders of magnitude higher activity on thymine hydroperoxide than that of other human enzymes such as selenium-dependent glutathione peroxidase and various representatives of glutathione transferases. The results indicate that Se-PHGPx may be an important enzyme in repairing oxidatively damaged DNA.

Animals↗
PubMed1997

A nonsense mutation due to a single base insertion in the 3'-coding region of glycogen debranching enzyme gene associated with a severe phenotype in a patient with glycogen storage disease type IIIa.

Glycogen storage disease type III (GSD-III) is an autosomal recessive disease resulting from deficient glycogen debranching enzyme (GDE) activity. A child with GDE deficient in both liver and muscle (GSD-IIIa) had recurrent hypoglycemia, seizures, severe cardiomegaly, and hepatomegaly and died at 4 years of age. Analysis of the GDE gene in this child by single-strand conformation polymorphism, followed by direct DNA sequencing and restriction analysis, revealed an insertion of a nucleotide A into position 4529 of the GDE cDNA (4529insA). This insertion resulted in substitution of a tyrosine to a stop codon at amino acid 1510 (Y1510X). The 4529insA mutation appeared to be homozygous in this patient and was not found in 20 unrelated controls or 18 other GSD-III patients (14 GSD-IIIa and 4 GSD-IIIb). This is the first identification of a disease mutation in this gene, and the data suggest that homozygous 4529insA may be associated with a severe phenotype in GSD-IIIa.

Glycogen Debranching Enzyme System↗
PubMed1997

Isolation and nucleotide sequence of canine glucose-6-phosphatase mRNA: identification of mutation in puppies with glycogen storage disease type Ia.

Two Maltese puppies with massive hepatomegaly and failure to thrive had isolated deficient glucose-6-phosphatase (G-6-Pase) activity in liver and kidney and pathological findings compatible with GSD-Ia. To identify the mutation, we cloned G-6-Pase canine cDNA by RT-PCR with primers from the murine G-6-Pase gene sequence. The canine G-6-Pase cDNA is 2346 bp, with a 5' untranslated region of 87 bp, a coding region of 1071 bp, and a 3' untranslated region of 1185 bp. The difference between the canine and human sequences is in the 3' untranslated region. A greater than 90% amino acid sequence homology was seen with canine, human, murine, and rat G-6-Pase. G-6-Pase cDNA from affected and control puppies revealed complete homology except at nt position 450, which showed a guanine to cytosine (G to C) transversion resulting in substitution of a methionine by isoleucine at codon 121 (M121I) in all five clones studied. The loss of an NcoI restriction site on genomic DNA amplified with primers flanking the mutation allowed us to prove that affected puppies were homozygous for the mutation and parents were heterozygous carriers. The mutant G-6-Pase cDNA had 15 times less enzyme activity than wild-type cDNA following transient transfection. Northern blot analysis of puppies with GSD-Ia revealed increased G-6-Pase mRNA, compared to normal controls. Increased G-6-Pase mRNA was also seen in normal fasted puppies compared to littermates in the fed state, suggesting that the increased G-6-Pase mRNA is a physiologic response to fasting. This is the first report of a molecularly confirmed naturally occurring animal model of GSD-Ia. The establishment of a breeding colony of this dog strain will facilitate studies on the role of G-6-Pase gene in glucose homeostasis, in pathophysiology of disease, and development of novel therapeutic approaches such as gene therapy.

Amino Acid Sequence↗
PubMed1997

Polymorphic markers of the glycogen debranching enzyme gene allowing linkage analysis in families with glycogen storage disease type III.

Glycogen storage disease type III (GSD-III), an autosomal recessive disease, is caused by deficient glycogen debranching enzyme (GDE) activity. We identified three polymorphic markers in the GDE gene using single strand conformation polymorphism (SSCP) analysis and DNA sequencing. They were -10G/A in the 5' non-translated region of exon 3,2001 + 8C/T in intron 16, and 3199C/T (P1067S) in exon 25. Two polymorphic markers (-10G/A and 2001 + 8C/T) were highly informative in both controls and GSD-III patients with heterozygosity values of 0.50 and 0.46, respectively. The third marker (3199C/T) had a heterozygosity value of 0.26. Restriction analysis of the PCR amplified genomic DNA products in two GSD-III families showed for the first time the potential use of these markers for carrier detection and prenatal diagnosis in this disease.

Base Sequence↗
PubMed1997

Preparation of animals with a high degree of chimerism by one-step coculture of embryonic stem cells and preimplantation embryos.

A single-step coculture procedure has been developed that can generate chimeric mice with high efficiency and reproducibility. The procedure involves culture of embryonic stem (ES) cells with 8- to 16-cell embryos in microwells to provide conditions for effective cell-cell-embryo contact. A suspension of ES cells is layered over the microwells, followed by transfer of an embryo without zona pellucida into each microwell. Following overnight culture, the blastocysts are transferred into pseudopregnant recipients. The method has several advantages due to its simplicity and reproducibility: (i) Over 90% of ES-cell contribution in new-borns can be obtained frequently and most of the chimeras display germ-line transmission. (ii) The procedure does not require specialized skills or expensive instruments. (iii) All the steps of embryo manipulation can be completed in a relatively short period of time; therefore, a large number of embryos can be manipulated simultaneously. The method was tested with three independent ES cell lines and two different strains of mice with similar results. The technique may be an alternative to microinjection of DNA into zygotes to prepare transgenic lines of small and large mammalian species.

Animals↗