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Biomedical subjects

D Yu

Publications and source records attributed to D Yu.

At least 199 records · Page 11Linked to original sources
PubMed1997

Cross-cultural consensus in personality judgments.

Building on recent research demonstrating consensus and accuracy in interpersonal perception based on minimal information, the present studies examined American and Chinese participants' within- and cross-cultural judgments. In Study 1, the authors used the zero-acquaintance paradigm in the People's Republic of China and found consensus on all personality dimensions. In Study 2, Chinese and American participants judged each other on the basis of photographs, and consensus was found among Americans' judgments of Chinese and Chinese participants' judgments of Americans. Further, by correlating target effects based on within-culture zero-acquaintance judgments and cross-cultural photographic judgments, the authors found agreement in the judgments of individuals by members of their own culture and the other culture for both Chinese and Americans.

China↗
PubMed1997

Sendai virus-based expression of HIV-1 gp120: reinforcement by the V(-) version.

BACKGROUND: We have established a system for recovering Sendai virus (SeV), a nonsegmented negative strand RNA virus, entirely from cDNA at an extremely high rate, and have succeeded in creating a V(-) SeV whose gene expression was greatly enhanced by the deletion of the nonessential V gene. Because of its extreme medical importance, there has been a strong need for the establishment of a better system to express the gp120 envelope glycoprotein of the human immunodeficiency virus type 1 (HIV-1) in sufficient quantity and purity. It also remains to be established to produce gp120 in in vitro natural host cells for HIV-1 such as human primary blood mononuclear cells, macrophages or established T cell lines. RESULTS: Using the above system, we created recombinant Sendai viruses expressing the gp120 in CV1 cells, a monkey kidney line. The expression level from the standard V(+) version has already reached 2.2/microg per 10(6) infected cells, which was readily purified from the culture fluid with a recovery rate of about 60%, and has so far appeared to be functionally and serologically authentic. The inserted gp120 gene was stably maintained during numerous passages of the recombinant virus. The V(-) version-based expression was even more robust, consistently reaching over 6.0 microg per 10(6) cells, a level that is one of the highest currently attainable for gp120 production in mammalian cells. Furthermore, a broad host range of SeV allowed gp120 production in all the three natural host cells for HIV-1 described above. CONCLUSIONS: SeV-based expression serves as a novel choice for producing large quantities of HIV-1 gp120 and will greatly facilitate biochemical, biological and immunological studies of this important glycoprotein.

DNA, Recombinant↗
PubMed1997

High-resolution EEG mapping of cortical activation related to working memory: effects of task difficulty, type of processing, and practice.

Changes in cortical activity during working memory tasks were examined with electroencephalograms (EEGs) sampled from 115 channels and spatially sharpened with magnetic resonance imaging (MRI)-based finite element deblurring. Eight subjects performed tasks requiring comparison of each stimulus to a preceding one on verbal or spatial attributes. A frontal midline theta rhythm increased in magnitude with increased memory load. Dipole models localized this signal to the region of the anterior cingulate cortex. A slow (low-frequency), parietocentral, alpha signal decreased with increased working memory load. These signals were insensitive to the type of stimulus attribute being processed. A faster (higher-frequency), occipitoparietal, alpha signal was relatively attenuated in the spatial version of the task, especially over the posterior right hemisphere. Theta and alpha signals increased, and overt performance improved, after practice on the tasks. Increases in theta with both increased task difficulty and with practice suggests that focusing attention required more effort after an extended test session. Decreased alpha in the difficult tasks indicates that this signal is inversely related to the amount of cortical resources allocated to task performance. Practice-related increases in alpha suggest that fewer cortical resources are required after skill development. These results serve: (i) to dissociate the effects of task difficulty and practice; (ii) to differentiate the involvement of posterior cortex in spatial versus verbal tasks; (iii) to localize frontal midline theta to the anteromedial cortex; and (iv) to demonstrate the feasibility of using anatomical MRIs to remove the blurring effect of the skull and scalp from the ongoing EEG. The results are discussed with respect to those obtained in a prior study of transient evoked potentials during working memory.

Adult↗
PubMed1997

Creation of an infectious recombinant Sendai virus expressing the firefly luciferase gene from the 3' proximal first locus.

A genetic engineering approach was made to generate a recombinant non-segmented negative-strand RNA virus, Sendai virus (SeV) of the family Paramyxoviridae, that expresses firefly luciferase. The DNA construct containing the entire open reading frame (ORF) of the luciferase gene followed by the SeV transcription stop and restart signals connected with the conserved intergenic three nucleotides was inserted immediately before the ORF of the viral 3'-proximal nucleocapsid (N) protein gene in a full-length SeV cDNA copy. After intracellular expression of full-length antigenomic transcripts from the engineered cDNA and of the viral n ucleocapsid protein and RNA polymerase from the respective plasmids, a recombinant SeV expressing luciferase activity at a high level was recovered, although the tendency of this particular reporter gene product to aggregate in cells made it difficult to estimate the maximum level of expression. The increase in genome length brought about by inserting 1728 nucleotides into the 15,384 nucleotide parental SeV was associated with reduced plaque size, slightly slower replication kinetics and a severalfold decrease in yield of the virus. The inserted luciferase gene was stably maintained after numerous rounds of replication by serial passages in chick embryos. These results indicate the potential utility of SeV as a novel expression vector.

Animals↗
PubMed1997

Characterization of ICP6::lacZ insertion mutants of the UL15 gene of herpes simplex virus type 1 reveals the translation of two proteins.

The herpes simplex virus type 1 (HSV-1) UL15 gene is a spliced gene composed of two exons and is predicted to encode an 81-kDa protein of 735 amino acids (aa). Two UL15 gene products with molecular masses of 75 and 35 kDa have been observed (J. Baines, A. Poon, J. Rovnak, and B. Roizman, J. Virol. 68:8118-8124, 1994); however, it is not clear whether the smaller form represents a proteolytic cleavage product of the larger form or whether it is separately translated. In addition, an HSV-1 temperature-sensitive mutant in the UL15 gene (ts66.4) is defective in both cleavage of viral DNA concatemers into unit-length monomers and packaging of viral DNA into capsids (A. Poon and B. Roizman, J. Virol. 67:4497-4503, 1993; J. Baines et al., J. Virol. 68:8118-8124, 1994). In this study, we detected two UL15 gene products of 81 and 30 kDa in HSV-1-infected cells, using a polyclonal antibody raised against a maltose binding protein fusion construct containing UL15 exon 2. In addition, we report the isolation of two HSV-1 insertion mutants, hr81-1 and hr81-2, which contain an ICP6::lacZ insertion in UL15 exon 1 and exon 2 and thus would be predicted to encode C-terminally truncated peptides of 153 and 509 aa long, respectively. hr81-1 and hr81-2 are defective in DNA cleavage and packaging and accumulate only B capsids. However, both mutants are able to undergo wild-type levels of DNA replication and genomic inversion, suggesting that genomic inversion is a result of DNA replication rather than of DNA cleavage and packaging. We also provide evidence that the 81- and 30-kDa proteins are the products of separate in-frame translation events from the UL15 gene and that the 81-kDa full-length UL15 protein is required for DNA cleavage and packaging.

Animals↗
PubMed1997

Specific inhibition of PCR by non-extendable oligonucleotides using a 5' to 3' exonuclease-deficient DNA polymerase.

The Stoffel fragment of Taq DNA polymerase lacks the 5' to 3' exonuclease activity that hydrolyzes potentially blocking DNA strands during primer extension. We there-fore asked whether by using this fragment in the PCR, non-extendable, base-paired oligonucleotides could inhibit amplification in a sequence-dependent manner. Model targets were chosen from the partially conserved ribosomal 16S rDNA of three bacterial species: E. coli, Bacillus subtilis and Neisseria gonorrhoea. A single pair of primers was capable of amplifying a homologous 240-bp region from all three. Two non-extendable "blocking" oligonucleotides were synthesized with sequences complementary to the inter-primer regions of E. coli and B. subtilis, respectively. Both blockers were shown specifically to prevent amplification of their complementary targets, but not of the reciprocal control targets or of the reciprocal control targets or of the non-complementary N. gonorrhea. Specificity was further confirmed by an internal positive control. Similar inhibition was seen with mixtures of targets in a single reaction. With intact Taq DNA polymerase, no blocking was observed. Primers and blockers targeting specific regions of N. gonorrhoea rDNA were used to confirm the requirement that blockers be directed to the inter-primer region. Sequence-dependent amplification inhibition, such as that demonstrated here, would be applicable to PCR-related strategies using primers capable of using multiple targets, where such selective inhibition could be useful.

Bacillus subtilis↗
PubMed1997

A 120 kilobase resolution contig map of the rice genome.

92% of the rice genome (4.3 x 10(8) bp, 2n = 24) was covered by 631 contigs of various length, which were generated by fingerprinting from a representative and genetically stable bacterial artificial chromosome (BAC) library of the Guang Lu Ai 4 (a O. Sativa variety) genome with the average insert of 120 kb in length. To form the contig map, 565 molecular markers of RFLP, STS, cDNA and anchor set derived from two O. Sativa varieties were by colony hybridization mapped to the contigs, which were then assigned to and ordered along the particular chromosomes according to the marker colinearity. Being highly conserved DNA sequences shared among the genomes of rice, barley, wheat, oat, maize, sorghum and sugar cane, 89 anchor markers mapped help to identify the rice genes through the information provided by the maps of relative genomes, and vice versa. Numerous repeated DNA sequences of various length were identified and mapped to the chromosomes. Physical distances have been determined for hundreds pairs of adjacent markers, which would facilitate the identification by map-based cloning the rice genes of interest. The accuracy of clone overlaps in contigs was further confirmed by the existence in contigs of well fit stacks of marker-lodged clones independently identified by hybridization. Large scale DNA sequencing of individual chromosomes could now be initiated simply by selecting and sequencing the minimally overlapped BAC clones of the contigs.

Alkyl and Aryl Transferases↗
PubMed1997

[Rhinometry of 176 normal adults with acoustic rhinometer].

RH-2000 acoustic rhinometer was used to measure nasal parameters in 176 normal adults. The results showed that nasal minimal cross-sectional area (NMCA) was 0.55 +/- 0.13 cm2 (x +/- s), and nasal cavity volume (NCV) 6 cm beyond the nostrils was 7.16 +/- 1.82 cm3. NMCA was located in the anterior edge of the inferior turbinate and the distance from the nostrils was 2.22 +/- 0.35 cm in 82.7% of the subjects; and the distance from the nostrils to the ostium internum was 0.79 +/- 0.25 cm in 17.3% of them. Our findings indicated that the narrowest segment of the nasal cavity was located in the anterior part, from the ostium internum to the anterior edge of the inferior turbinate. NMCA and NCV were larger in male than in female (P < 0.05). There was significant difference in NMCA and NCV between two sides(P < 0.001). The width of the nasal cavity between two sides might also be different. The measured NMCA and NCV was larger in subjects above 60 years old(P < 0.01, P < 0.05). Acoustic rhinometry is a new objective method to assess the geometry of nasal cavity. NMCA is a valuable objective mark to evaluate nasal patency.

Acoustics↗
PubMed1997

Potassium channels on cardiomyocytes of selenium iodine deficiency rats and iodine deficiency rats.

Using diet control method to feed the weaning male Wistar rats with selenium and iodine deficiency Keshan endemic area food for 8 weeks to set up animal model. Singal channel recording in cell attached model was used to measure cardiac cell membrane potassium channel conductances, which coincide with the cardiac cell membrane potassium channel conductances in normal Wistar rats. The potassium channel conductance on selenium and iodine deficiency rat cardiac cell membrane is showing current-voltage increasing lineally in the range of clamping voltage 0 +/- 30 mV with channel conductance of 43.4 pS. The channel current does not increase depending on the clamping voltage that is showing the rectifying characteristic and the channel current amplitude can be augmented by added KIOa 5 mmol/L in bath solution. A kind of inward rectifying potassium channel activity was recorded, but this channel activity disappeared after lasting 6-10 minutes only. Then an inward rectifying potassium channel with the conductance of 14.2 pS was activated by KIOa 5 mmol/L introduced to bath solution. Both conductances are less than that of normal Wistar rats.

Animals↗
PubMed1997

[Study on the relationship between the expression of adhesion molecules and the invasiveness of acute myeloid leukemia cells].

OBJECTIVE: To study the relationship between the expression of adhesion molecules CD49d (VLA-4) and CD11a (LFA-1) and the invasiveness of acute myeloid leukemia (AML) cells. METHODS: Peripheral blood and/or bone marrow samples from 50 AML patients were investigated by APAAP and Western blotting method. RESULTS: Extramedullary invasion developed in 32 of 50 patients (64%). The expression of CD49d and CD11a in the invasive group was much higher than that in the non-invasive group (P<0.005), while the difference between the leukemic cells from bone marrow and peripheral blood for CD49d/CD11a expression was not significant. CONCLUSION: AML cells might adhere to and get through vascular endothelium by CD49d/VCAM-1 and CD11a/ICAM-1 adhesion mechanism, and the expressions of CD49d and CD11a were not critically responsible for the release of leukemic cells from bone marrow.

Adolescent↗
PubMed1997

Anticalculus efficacy of an essential oil dentifrice containing 1.3% pyrophosphate ion.

One-hundred and fifty (150) healthy adult subjects, who readily form dental calculus under normal brushing conditions, completed this study to determine the efficacy of an essential oil dentifrice formulation containing 1.3% pyrophosphate ion (PPi) in inhibiting the development of supragingival calculus, compared to a commercially available control dentifrice (Crest Regular). This study was conducted in two phases: an 8-week pre-trial phase (Phase I) to identify a suitable calculus forming population, and a 12-week trial phase (Phase II) utilizing a randomized, double-blind, parallel group design. Calculus scores from Phase I were used to form balanced groups for Phase II. At the start of Phase I, subjects received a thorough dental prophylaxis and were instructed to brush twice daily for 60 seconds with the control dentifrice. At 8 weeks, subjects were scored for calculus; subjects with a Volpe-Manhold Calculus Index score > or = 7.0 qualified to enter Phase II. Qualifying subjects were stratified by calculus scores and randomly assigned to one of two treatment groups. Subjects then received a baseline oral soft tissue examination and dental prophylaxis, and began twice-daily brushing with their assigned dentifrice for 12 weeks. At 12 weeks, subjects received an oral soft tissue examination and were re-scored for calculus. The 1.3% PPi dentifrice group mean score was statistically significantly different (p = 0.03) from the control dentifrice group mean score, producing a 14.1% calculus reduction. In this study the essential oil dentifrice containing 1.3% pyrophosphate ion was effective in inhibiting the development of supragingival calculus.

Adult↗
PubMed1997

[A comparative chromosome map between human and Hylobates hoolock built by chromosome painting].

We established chromosomal homologies between all human chromosomes except Y and those of Hylobates hoolock by chromosome painting (chromosome in situ suppression hybridization with human chromosome-specific DNA libraries). Human chromosomes 9,13,15,18,21,22,X libraries hybridized to single G-banding H. hoolock chromosomal region, other human DNA libraries showed at least two homologous segments in H. hoolock chromosomes. 59 segments homologous to one of 22 human autosomes were detected in 18 H. hoolock autosomes. There were at least 39 translocations. Thus an uniquivocally high degree of synteny between human and H. hoolock was confirmed. This will finally allow H. hoolock to be integrated into the overall picture of chromosomal evolution in Hylobatids.

Animals↗
PubMed1997

[Clinical and experiment study of cooling therapy on burned wound].

OBJECTIVE: To observe the subjective benefit of pain relief by cooling therapy when wound temperature drops to below 28 degrees C (threshold for pain). METHOD: 22 patients with partial-thickness burns who received cooling therapy showed 2 days early healing as compared with untreated burn wounds. As a first aid measure, prolonged cooling therapy (up to 30') was recommended. In experimental study, the protective effects with cooling therapy were observed in wistar rats with deep second degree burns. RESULTS: Lower epithelial cell activity and higher schiff alkaline values were seen in the wound skin tissue in the non cooling therapy than in early cooling therapy groups and healthy controls. The groups with early cooling therapy (at once, 10', 20' after scalded injuries) the epithelial cell activity maintained at 83%, 80%, 65%. CONCLUSION: The results suggest that cooling therapy can protect the epithelial cell activity to some extent after scalded injuries which may be associated with inhibition of lipid peroxide.

Adult↗
PubMed1997

Adenovirus E1A expression enhances the sensitivity of an ovarian cancer cell line to multiple cytotoxic agents through an apoptotic mechanism.

The introduction of adenovirus 5 E1A into the SKOV3ip1 ovarian cancer cell line was shown previously to suppress HER2/neu expression and reduce the malignant potential of these cells (Yu et al., Cancer Res., 53: 891-898, 1993). In this report, we show that reduction of p185 in cells stably expressing E1A protein was coincident with increased sensitivity to cytotoxic agents. The LD50 of cisplatin was reduced 6-fold, and the LD50 of paclitaxel and doxorubicin was reduced 10-fold in E1A-expressing cells compared with control cells. The growth of SKOV3ip1 and control cells was unchanged in the presence of 150 ng/ml of tumor necrosis factor-alpha, whereas the growth of E1A-expressing cells was reduced by 30 to 40%. When we used a physiologically obtainable concentration of paclitaxel (0.5 microM), DNA laddering consistent with apoptotic cell death was seen after a 24-h exposure in the E1A-expressing cells, whereas laddering and DNA fragmentation were only detected in DNA from control cells after longer exposure (48 h) at a 20-fold higher concentration of paclitaxel. The SKOV3ip1 cells do not express p53 protein; hence, the induction of apoptosis by paclitaxel is through a p53-independent pathway. Despite their diverse mechanisms of action, the cytotoxic effects of cisplatin, doxorubicin, paclitaxel, and tumor necrosis factor-alpha were enhanced by the expression of E1A proteins in the SKOV3ip1 ovarian cancer cells. This suggests that these agents share a common final pathway of cell killing, which may represent a potential therapeutic target in resistant ovarian cancers.

Adenovirus E1A Proteins↗
PubMed1997

Isolated limb perfusion in the sarcoma-bearing rat: a novel preclinical gene delivery system.

Reliable site-specific delivery of genetic constructs remains a challenging component of gene-based therapy of solid tumors. Isolated limb perfusion (ILP) continues to be evaluated for treatment of locally advanced soft tissue sarcomas because this approach uniquely directs therapeutic agents into the tumor-bearing extremity without significant systemic leak. In light of these considerations, we tested the hypothesis that ILP could be used to deliver genes carried in viral vectors to the sarcoma-bearing rat extremity, resulting in demonstrable gene transfer into the tumor. ILP was performed in rats by cannulating the femoral artery and vein, isolating the hind limb from systemic circulation by tourniquet, and cycling perfusate for 15 min at a rate of 2.4 ml/min. Leakage into the systemic circulation was 7.5% of the total perfusate concentrated in the isolated limb, as determined by perfusion with technetium 99m-tagged RBCs. We used the ILP technique to perfuse rat hind limbs bearing syngeneic fibrosarcoma tumor nodules with the replication-defective adenovirus Ad5LacZ, which expresses the bacterial beta-galactosidase. 5-Bromo-4-chloro-3-indolyl-beta-D-galactoside staining of the perfused limb tissues confirmed gene transfer to the tumor and peritumoral tissue, demonstrating that the tumor was part of the perfusion circuit and that gene therapy delivered via this method was feasible. These results suggest that adaptation of this preclinical gene delivery model to administer genetic constructs aimed at controlling tumor growth may prove beneficial to patients with extremity sarcomas.

Adenoviruses, Human↗
PubMed1997

[Laser Raman spectral analysis of superhelical spatial conformation on plasmid DNA].

The pBR322 recombinant plasmids DNA products, which purified by phenol-extract and equilibrium centrifugation in CsCl-ethidium bromide gradients, have been shown as mainly spatial conformation of covalently closed circular DNA (i.e. cccDNA) by agarose gel electrophoresis for homogeneity detection. Laser Raman spectra in the region 450-1750 cm-1 have been obtained for the circular double-stranded plasmids DNA molecule in an aqueous solution, indicating not only contain those marker peaks of secondary structure as in conventional B-form of DNA, but also present both 854 and 1083 cm-1 diagnostic bands of reflecting the vibration state of deoxyribosyl phosphodiester backbone. The present analysis have demonstrated relationship between the superhelical state for cccDNA and the two conformational marker bands that can be considered as the tertiary structure marker on plasmids DNA. Because of markedly Raman hypochromicity of charecter band 1378cm-1 of dT in contrast to liear DNA molecule, as well as the carbonyl double bond vibration line of dT have shifted to higher wave number position, the base stacking analysis represent occurrence of both increase in staking reaction activity of dT, and injury of a number of the Hoogsteen hydrogen bond between dA and dT with exist supercoil structure in cccDNA.

DNA, Circular↗
PubMed1996

Overexpression of c-erbB-2/neu in breast cancer cells confers increased resistance to Taxol via mdr-1-independent mechanisms.

It has been reported that breast tumors that overexpress c-erbB-2/neu are less responsive to certain adjuvant chemotherapy regimens than those that express a normal amount of the gene product. To investigate whether overexpression of the c-erbB-2/neu-encoded p185 can indeed lead to increased chemoresistance in breast cancers, we introduced the human c-erbB-2/neu gene into the very low p185-expressing MDA-MB435 human breast cancer cells and examined Taxol sensitivities among the parental MDA-MB-435 cells and stable transfectants which express increased levels of p185. The p185-overexpressing MDA-MB-435 transfectants were more resistant to Taxol than the parental cells. The increased Taxol resistance was not accompanied by changes in doubling time and S-phase fraction. The increased Taxol resistance was independent from oncogenic transformation since it was observed only in c-erbB-2/neu-transformed cells and not ras-transformed cells when oncogene-transformed NIH3T3 cells were examined. To study whether p185 induced Taxol resistance through the mdr-1 pathway, we examined the mdr-l-encoded p170 levels in these transfectants. The MDA-MB-435 cells expressed very low levels of p170 and there was no increase of p170 expression in the p185-overexpressing MDA-MB-435 transfectants. Furthermore, these transfectants were not sensitized to Taxol treatment by mdr-1 blocker thioradazine. These data demonstrated that overexpression of c-erbB-2/neu can lead to intrinsic Taxol resistance independent from mdr-1 mechanisms.

ATP Binding Cassette Transporter, Subfamily B, Mem↗