Biomedical subjects

M Yang

Publications and source records attributed to M Yang.

At least 343 records · Page 19Linked to original sources

PubMed1997

[9-cis retinoic acid induces apoptosis in HL-60 cells].

OBJECTIVE: To investigate the apoptosis of HL-60 cells induced by 9-cis retinoic acid (9-cis RA), and illustrate the possible molecular mechanism. METHODS: Apoptosis was detected by morphological observation, DNA electrophoresis and flow cytometric cell cycle analysis. Bcl-2 expression was detected by flow cytometry. RESULTS: 9-cis RA initiated apoptosis of HL-60 cells after inducing them irreversibly commited to differentiation. Bcl-2 was downregulated during the differentiation and apoptosis process. 9-cis RA was more potent than all-trans retinoic acid (ATRA) did in inducing terminal differentiation associated apoptosis and in downregulation of Bcl-2 expression. CONCLUSION: 9-cis RA can induce apoptosis in HL-60 cells. Downregulation of Bcl-2 expression appears to play an important role in the apoptosis of the differentiated leukemic cells.

Alitretinoin↗

PubMed1997

ASCUS on cervical cytologic smears. Clinical significance.

OBJECTIVE: To determine the significance of the category atypical squamous cells of undetermined significance (ASCUS) in predicting the presence of underlying squamous intraepithelial lesion (SIL) and to determine the best follow-up method. STUDY DESIGN: Follow-up studies of all cervical cytologic smears with a diagnosis of ASCUS within 14 months were reviewed. RESULTS: SIL was diagnosed in 66.67% of ASCUS patients upon follow-up with biopsies with and without smears. SIL was diagnosed in 17.39% of ASCUS patients upon follow-up with smears only. CONCLUSION: Based on this study, ASCUS on smears serves as a good marker of underlying SIL. Follow-up studies with biopsies with and without smears appear to be more effective in detecting underlying low grade SIL than repeat smears only.

Biopsy↗

PubMed1997

Identification of PDGF receptors on human megakaryocytes and megakaryocytic cell lines.

Platelet-derived growth factor (PDGF) is a potent chemotactic and mitogenic factor implicated to play important roles in a variety of normal and pathophysiologic settings. We investigated PDGF receptor expression on human megakaryocytes and several megakaryocytic cell lines (CHRF, DAMI, Meg-01, M-07e) using enzyme-linked immunosorbent assay (ELISA), flow cytometry and immunocytochemical staining. Both PDGF receptor subtypes were identified on CHRF, DAMI, and Meg-01 cells by ELISA; PDGF beta-receptor levels exceeded alpha-receptor levels. Flow cytometry revealed that beta-receptor levels on CHRF and DAMI cells exceeded those on Meg-01 cells, and that M-07e expressed neither receptor. Immunocytochemical staining confirmed these findings and determined that bone marrow megakaryocytes also expressed PDGF receptors. Exposure of megakaryocytes to PDGF-BB dramatically induced the expression of the immediate-early gene, c-fos, within 30 min. Moreover, PDGF-BB significantly stimulated CHRF proliferation and colony formation. The present study demonstrates the presence of functional PDGF receptors on human megakaryocytes and their ability to mediate a mitogenic response.

Cell Line↗

PubMed1997

[The change of serotonin of venous blood in pregnancy induced hypertension].

OBJECTIVE: To provide evidence to the hypothesis that the involvement of serotonin (5-HT) takes part in the pathogenesis of pregnancy induced hypertension (PIH). METHOD: 31 pregnant women with PIH and 20 normotensive pregnant women were studied in the present study. Venous plasma 5-HT and platelet 5-HT from all subjects were measured with spectrometry. RESULTS: The mean platelet 5-HT level in PIH group (24.69 +/- 17.79 micrograms/L) was less than that in normotensive group (91.06 +/- 47.77 micrograms/L) (P < 0.01). The mean plasma 5-HT level in PIH group (48.65 +/- 19.29 micrograms/L) was significantly higher than that in normotensive group (35.39 +/- 12.88 micrograms/L) (P < 0.01). CONCLUSION: Plasma levels of 5-HT in PIH were elevated significantly, this might be largely caused by the increased release of 5-HT by platelet. The results show that elevated level of 5-HT in patients with PIH might take part in the pathogenesis of PIH.

Adult↗

PubMed1997

[Immunohistochemical locating and quantitative studies of 5-hydroxytryptamine and 5-hydroxytryptamine receptor in placental villi of patients with pregnancy induced hypertension].

OBJECTIVE: To supply evidence of relationship between pregnancy induced hypertension (PIH) and 5-hydroxytryptamine (5-HT) and 5-hydroxytryptamine receptor (5-HTR) synthesized by placental villi. METHODS: Five normal placentas and 15 placentas of PIH were used for studying localization and quantification of 5-HT and 5-HTR in placental villi by using immunohistochemical and in situ quantitative methods. RESULTS: Syncytiotrophoblasts and capillary endothelium in placental villi of control group showed 5-HT and 5-HTR positive immunoreaction, but in placental villi of group with PIH, syncytiotrophoblasts appeared 5-HT and 5-HTR weak positive immunoreaction and capillary endothelium appeared 5-HT and 5-HTR weak positive or negative immunoreaction. The results of in situ quantitation showed that the content of 5-HT and 5-HTR in placental villus syncytiotrophoblasts of group with PIH were significantly lower than those in the control group. CONCLUSIONS: The content of 5-HT and its receptor in placenta may be related to PIH.

Adult↗

PubMed1997

Observation of developing cercaria of Schistosoma japonicum on ultrastructural level and remarks at its morphology of mature stage.

OBJECTIVE: To study the developing cercaria of Schistosoma Japonicum (S. japonicum) on ultrastructural level by transmission electron microscope (TEM) for analyzing the morphological dynamic changes of the tegument, glands and musculature. METHODS: Artificial infected Oncomelania hupensis were dissected under dissecting microscope and the daughter sporocysts picked up for studying the germinal cells stage (S1). The other embryonic cercaria were selected according to the modified parameter of Chen and Bier (1972). The specimens were prepared by conventional procedure of the laboratory of TEM and were observed by Hitachi H600. RESULTS: Beside the germinal cell stage (S1), this is the first chronological study on the morphological development of S. japonicum cercaria from S2-S5 concerning the tegument and its elements (glycocalyx, sensory papilla, basal lamina and spine), head and acetabular gland and musculature of the body and tail. This article discusses the ultrastructural morphological differences from prior authors and emphasizes on the postacetalar gland and the pattern of tail musculature of the matured stage cercaria. CONCLUSIONS: According to the cell division and differentiation, the process of development may be divided into 5 stages: S1, the single germinal cell stage; S2, the germinal ball stages: major multiplication and minor differentiation; S3, tail budding embryonic stage, both active in multiplying and differentiating; S4, the pre-matured stage, major differentiation and minor multiplication; and S5, the fully matured stage (completing the differentiation).

Animals↗

PubMed1997

[Effects of breakfast quality on blood glucose level in students].

Thirty freshmen were randomly enrolled and their blood glucose levels in fasting and one, two and three and a half hours after breakfast with three different kinds of calorie allocation were determined to explore the effects of breakfast quality on their blood glucose levels. Results showed that changes of blood glucose level curve in fasting students was low and horizontal. Blood glucose level after breakfast with carbohydrate as major composition increased significantly one hour after breakfast but could not last for a long time, and decreased rapidly one hour later and down to approximately normal three and a half hours after breakfast. Blood glucose level after breakfast with higher lipid and protein composition increased gradually and maintained at a medium level, and was still higher three and a half hours after breakfast than that with other breakfast; and blood glucose level one hour after breakfast with reasonable calorie allocation increased more rapidly and was kept at a higher and more stable level, and still approximated to that with higher lipid and protein composition three and a half hours after breakfast. It suggests that reasonable allocation of nutrients in breakfast plays an important role in maintaining blood glucose level in the morning, and unhealthy fasting habit in the morning should be abandoned.

Adolescent↗

PubMed1996

When the brain changes its mind: interocular grouping during binocular rivalry.

The prevalent view of binocular rivalry holds that it is a competition between the two eyes mediated by reciprocal inhibition among monocular neurons. This view is largely due to the nature of conventional rivalry-inducing stimuli, which are pairs of dissimilar images with coherent patterns within each eye's image. Is it the eye of origin or the coherency of patterns that determines perceptual alternations between coherent percepts in binocular rivalry? We break the coherency of conventional stimuli and replace them by complementary patchworks of intermingled rivalrous images. Can the brain unscramble the pieces of the patchwork arriving from different eyes to obtain coherent percepts? We find that pattern coherency in itself can drive perceptual alternations, and the patchworks are reassembled into coherent forms by most observers. This result is in agreement with recent neurophysiological and psychophysical evidence demonstrating that there is more to binocular rivalry than mere eye competition.

Animals↗

PubMed1996

Structure and characterization of rat cyclin D3 promoter.

To investigate the transcription initiation mechanism of the gene encoding cyclin D3, one of the major G1 cyclins to promote the G1/S transition, we cloned the 5' portion of rat cyclin D3 gene and analyzed the promoter region. The major transcription start point of the gene was identified by the primer extension experiment to be 207 bp upstream from the ATG start codon and its promoter region was found to have no canonical TATA box. The DNA mobility shift assay and DNase I footprinting analysis using nuclear extracts from Nb2 cells stimulated by prolactin (PRL) have clearly revealed that the promoter possesses two binding sites for the PRL-induced transcription factors. One is located between -1 and -59 bp (Region I) and the other between -328 and -380 bp (Region II). The induction of transcription factors by PRL was blocked by simultaneous addition of cycloheximide, suggesting that protein synthesis was necessary for the release of these PRL-responsive transcription factors. Region I contained putative binding elements for ATF/CREB, SP1 and AP2, and Region II contained elements for a MCBF/MGF and a novel factor. These results suggest that the cyclin D3 gene is a TATA-less gene whose transcription is regulated by multiple mitogen-inducible transcription factors including an unknown factor.

Amino Acid Sequence↗

PubMed1996

Distribution and localization of NMDA receptor subunit 1 in the visual cortex of strabismic and anisometropic amblyopic cats.

ACTIVATION of NMDA (N-methyl-D-aspartate) receptors has recently been proposed as a prerequisite for the induction of experience-dependent modification of visual cortical neurones seen during early postnatal development. A new monoclonal antibody to the NMDA receptor subunit 1 (NMDA-R1) has been used to localize and compare the distribution of the receptors in the primary visual cortex of normal cats and those raised with either amblyopia induced by monocular optical blur or monocular esotropic strabismus. Although all three groups showed densest labelling in layers II-III, a comparison of immunopositive cells at any depth below the cortical surface showed a significantly lower frequency in strabismic and anisometropic cats than in normal cats, but a greater frequency in anisometropic cats that in strabismic animals. There appears to be no direct relationship between the expression of NMDA-R1 receptors and the level of excitability, binocularity or neuronal acuity known to exist in either of these two cat models of amblyopia, thus raising further questions as to the precise nature of the role of NMDA receptors in the processes of visual cortical plasticity.

Amblyopia↗

PubMed1996

Carbohydrate-mediated regulation of matrix metalloproteinase-2 activation in normal human fibroblasts and fibrosarcoma cells.

Matrix metalloproteinase-2 (MMP-2) is activated on the cell surface by membrane type 1-MMP (MT1-MMP). Activation of proMMP-2 is induced in vitro by concanavalin A (ConA). The regulation of proMMP-2 activation is, however, not yet fully understood. We investigated the effect of plant lectins, carbohydrates and inhibitors of the cytoskeleton on proMMP-2 activation in normal (HLF1) and malignant fibroblast (HT1080) cells. Native ConA induced proMMP-2 activation in both cell types while dimeric succinyl-ConA had no effect, suggesting that receptor clustering is involved in activation. Wheat germ agglutinin (WGA) also induced proMMP-2 activation. N-acetyl-D-glucosamine (GlcNac) inhibited the effects of ConA and WGA while mannose only inhibited ConA-induced proMMP-2 activation. Mannose also inhibited the expression of MT1-MMP mRNA induced by ConA. Cytochalasin B and colchicine had no effect on the ConA induction of proMMP-2 activation. These studies help to define some of the cellular and molecular mechanisms for the induction of proMMP-2 activation.

Acetylgalactosamine↗

PubMed1996

Cloning and developmental expression of a membrane-type matrix metalloproteinase from chicken.

We have cloned a novel matrix metalloproteinase (MMP) from cultured chicken embryo fibroblasts. The cDNA-derived protein sequence contains 608 amino acids including a C-terminal hydrophobic transmembrane domain of 24 amino acids and a cytoplasmic domain of 20 amino acids. This chicken MMP is 72% similar to a recently described membrane-type MMP (MT-MMP) from human placenta (Sato, H., Takino, T., Okada, Y., Cao, J., Shinagawa, A., Yamamoto, E., and Seiki, M. (1994) Nature 370, 61-65). Accordingly, we name this novel MMP chicken MT-MMP. As shown by Northern blotting, two MT-MMP mRNAs of 6 and 10 kilobases are constitutively expressed but only modestly regulated by growth factors and cytokines in cultured chicken embryo fibroblasts. Both mRNAs are abundant in the head and body of 8- and 9-day-old chicken embryos. As shown by in situ mRNA hybridization, MT-MMP is expressed in embryonic neural tube, spinal ganglia, and respiratory epithelium, as well as in developing cartilage and muscle. Using reverse transcription-polymerase chain reaction, we have found MT-MMP mRNA in 2-day-old chicken embryos and extraembryonic membranes. In addition, a strong correlation was observed between the mRNA expression of MT-MMP and 72-kDa type IV collagenase. Collectively, the early MT-MMP mRNA expression and its co-localization in several tissues with 72-kDa type IV collagenase mRNA suggest that the MT-MMP plays an important role in early development.

Amino Acid Sequence↗

PubMed1996

Effects of gemfibrozil on very-low-density lipoprotein composition and low-density lipoprotein size in patients with hypertriglyceridemia or combined hyperlipidemia.

To examine the effects of gemfibrozil on very-low-density lipoprotein (VLDL) composition and low-density lipoprotein (LDL) size, five men with hypertriglyceridemia (HTG) alone and five men with HTG and hypercholesterolemia (combined hyperlipidemia, CHLP) were randomized for 8 weeks to Lopid SR (slow-release gemfibrozil; two 600-mg tablets once per day) or placebo in a crossover study. Drug therapy versus placebo significantly decreased plasma triglyceride (68%), and VLDL (77%), and significantly increased high-density lipoprotein cholesterol (25%); total cholesterol, apolipoprotein B and lipoprotein[a] concentrations did not change significantly. With drug, mean total apoE in plasma was 53% lower in patients with HTG and 39% lower in patients with CHLP. Gemfibrozil significantly affected VLDL composition: protein increased 26%, molar ratio of apoE to apoB reduced 48%, apoC-II increased 19%, and apoC-III decreased 9%. LDL cholesteryl ester significantly increased with drug treatment. VLDL subfractions were separated and classified as heparin binding (VLDLR, apoE rich) or nonbinding (VLDLNR-1 and VLDLNR-2, both apoE poor). All VLDL subfractions were significantly lower with drug therapy, and the differences for total VLDL and for VLDL subfractions were greater in patients with HTG. With placebo, VLDLR accounted for 41.8% of VLDL in HTG and 49.0% of VLDL in CHLP, reduced to 27.6% and 38.6%, respectively, with gemfibrozil. Taken together, these results suggest that treatment with gemfibrozil reduces plasma concentrations of VLDL and alters the apoprotein composition of VLDL in a manner that may favor LDL- and VLDL-receptor-mediated clearance of the apoE-rich VLDL subfraction, thereby reducing TG-rich particle concentrations, and possibly reducing risk for coronary heart disease.

Adult↗

PubMed1996

Conformational flexibility of three-way DNA junctions containing unpaired nucleotides.

Time-resolved fluorescence resonance energy transfer has been used to examine the global structure and conformational flexibility of three-way DNA junctions containing unpaired bases at the branch point. Three-way junctions were prepared with donor (fluorescein) and acceptor (tetramethyl-rhodamine) dyes attached to the ends of different helical arms in various pairwise combinations. The time-resolved fluorescence decay of the donor in each labeled junction was measured by time-correlated single photon counting. The distributions of donor-acceptor (D-A) distances present between each pair of labeled helices were recovered from analysis of the donor decay profiles using a Gaussian distribution model. The recovered D-A distance distributions reveal the mean distance between each pair of helices, as well as the range of distances that exists between each pair. For the junction lacking unpaired bases, the three mean interarm distances are similar, indicating an extended structure. In addition, a relatively broad range of distances is present between each pair of helices, showing that the structure is flexible. The addition of unpaired bases causes the junction to fold into a different structure, with one interarm distance being shorter than the other two. The change in overall geometry of the junction appears to be primarily due to the repositioning of one of the helices flanking the bulge. In bulged junctions containing unpaired thymine, cytosine, or adenine bases, the helix containing the 3' portion of the bulged strand appears to undergo the greatest change in its mean position relative to the other helices. In contrast, in the bulged junction containing unpaired guanine bases, the helix containing the 5' portion of the bulged strand is displaced. In all bulged junctions, there is a wide range of distances between the perturbed helix and the other two helices, indicating high mobility for the perturbed arm. These results indicate that the overall structure and conformational flexibility of three-way DNA junctions are sensitive to the presence of unpaired bases at the branch point of the junction and that the precise effect of a bulge depends on the nature of the unpaired bases.

Base Composition↗

PubMed1996

Non-oxidative modification of native low-density lipoprotein by oxidized low-density lipoprotein.

The oxidative modification of low-density lipoprotein (LDL) has been implicated in the pathogenesis of atherosclerosis, although little is known as yet about the precise mechanism of oxidation in vivo. The studies presented here demonstrate that, in the absence of cells or transition metals, oxidized LDL can modify native LDL through co-incubation in vitro such as to increase its net negative charge, in a concentration-dependent manner. The interaction is not inhibited by peroxyl radical scavengers or metal chelators, precluding the possibility that the modification of native LDL by oxidized LDL is through an oxidative process. Studies with radioiodinated oxidized LDL showed no transfer of radioactivity to the native LDL, demonstrating that fragmentation of protein and the transfer of some of the fragments does not account for the modified charge on the native LDL particle. The adjacency of native to oxidized LDL in the arterial wall may be a potential mechanism by which the altered recognition properties of the apolipoprotein B-100 may arise rapidly without oxidation or extensive modification of the native LDL lipid itself.

Acetylation↗

PubMed1996

Cloning differentially expressed genes by linker capture subtraction.

We have developed a simple and effective method, designated linker capture subtraction (LCS), for cloning differentially expressed genes between two cell types or between cells treated in two different ways. In the first step of the method, two mRNA populations are converted to double-stranded cDNAs, fragmented, and ligated to linkers for PCR amplification. In the second step, the linkered DNA (tester) from one mRNA population is hybridized to an excess of the unlinkered DNA (driver) from the other mRNA population, followed by incubation with mung bean nuclease which digests single-stranded DNA specifically. This leaves only tester-tester homohybrids to be amplified by PCR in the following step, so as to achieve an enrichment of tester-specific sequences. The amplified PCR products are then used as tester for another round of subtraction. The process of subtraction is carried out three times, and the final PCR products are inserted into a vector for clonal analysis. We have used the strategy to begin to clone and identify the genes expressed differentially between the human prostate cancer cell lines LNCaP and PC-3, which have different tumorigenic and metastatic potentials. We demonstrated strong enrichment of target sequences. We also report the identities of two of the genes expressed differentially in these cell lines. One is prostate-specific antigen (PSA) which is known to be expressed in LNCaP but not in PC-3. The other is vimentin, the differential expression of which has not been reported previously in these prostate cancer cells.

Base Sequence↗

PubMed1996

Prolactin induces switching of T-cell receptor gene expression from alpha to gamma in rat Nb2 pre-T lymphoma cells(1)

Prolactin (PRL) is considered to be an immunomodulator. This study was conducted to analyze the actions of PRL on the gene expressions for T-cell receptor (TCR) chains in a fat pre-T lymphoma cell line, Nb2. PRL remarkably stimulated the gene expression for TCR gamma chain within 4 h and suppressed TCR alpha chain mRNA expression within 8 h in Nb2 cells. The expression of TCR beta mRNA in the cells was concomitantly, but to a less extent, repressed by the hormone treatment. These results suggest that PRL may participate in the regulation of mammalian T-cell differentiation and development.

Amino Acid Sequence↗

PubMed1996

Evidence for a relation between inspired gas mixture and the left ventricular contrast achieved with Albunex in a canine model.

BACKGROUND: In a previous experiment, a marked reduction in the right- and left-sided contrast effect of Albunex was noted in an intubated animal spontaneously breathing isoflurane in 100% oxygen. The theory suggests that the time course of echogenicity of microbubbles in liquid is dependent on the pressure and the gradients of dissolved gases. The present set of experiments tested whether the loss of contrast occurs at commonly used therapeutic concentrations of inspired oxygen. HYPOTHESIS: This research tested the hypothesis that the left ventricular (LV) contrast effect achieved with intravenous injection of the ultrasound contrast agent Albunex is related to the inspired oxygen content. METHODS: Intubated dogs were maintained in a spontaneously respiring anesthetic state on isoflurane and mixtures of oxygen (12-50%) in nitrogen. FIO2 was held steady for 15 min prior to injection of 0.08 ml/kg of Albunex. The contrast effects were recorded from a transthoracic short-axis view. Left and right ventricular brightness curves were generated from digitized sequences of end-diastolic frames. The minimum and maximum brightness and area under the time-brightness curves were determined. RESULTS: The LV maximum brightness and area under the curve showed significant negative correlations (p = < 0.004) with the FIO2, while the minimum brightness showed a significant positive correlation (p = < 0.002). No significant correlations were found for the right ventricular brightness parameters. CONCLUSIONS: These findings show an important relationship between the FIO2 and loss of the contrast effect of Albunex. This loss occurs at oxygen concentrations in the therapeutic range, but could be overcome by increasing the dose of Albunex. The mechanism is likely related to an outward nitrogen gradient causing a loss of echogenicity. The clinical implication is that patients on supplemental oxygen may require higher doses of Albunex to achieve optimal opacification.

Albumins↗