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Biomedical subjects

L Song

Publications and source records attributed to L Song.

At least 91 records · Page 5Linked to original sources
PubMed2000

[Study of IL-6 signal transduction pathway in a human multiple myeloma cell line--Sko-007].

OBJECTIVE: To investigate the IL-6 signal transduction pathway in a human multiple myeloma (MM) cell line--Sko-007. METHODS: The electrophoretic mobility shift assay (EMSA) and immunoprecipitation were used to detect the activation of IL-6-related transcription factors(TFs)--STAT3, NF-IL-6, NF-kB and protein kinase ERK, Jak1 in Sko-007 cells stimulated by IL-6. RESULTS: Both the transcription factors-STAT3, NF-IL-6 and protein kinases-Jak1, ERK were activated by IL-6 in Sko-007 cells. CONCLUSION: The biological function of IL-6 on Sko-007 cells is mediated by the activation of Jak/STAT and Ras/NF-IL-6 signal transduction pathways.

Humans↗
PubMed2000

[Species composition and distribution of algae in semi-desert algal crusts].

Twenty-two species of algae, including 10 Cyanophyta, 4 Chlorophyta, 6 Bacillariophyta and 2 Euglenophyta, were isolated and identified from the semi-desert algal crusts in Shapotou, Ningxia Autonomous Region. The relationship between algae and soil matrix was studied by grinding and superprobe, and the distribution of algal species in eight layers of crusts was examined under light and scanning electron microscopes. It was found that the algae exhibited a layer-typed distribution in intermicron, and the layers of algal crust from surface to inner were in order of inorganic mineral protection layer(ca. 0.02 mm), alga-enriched layer(0.02-2.5 mm) and sparse algae layer(2.5-5.0 mm). The filaments of algae were united with clay mineral by the polysaccharides and protein of their sheath, or extended directly into mineral granules to network and band sand and soil particles.

Climate↗
PubMed2000

[N cycle of rubber-tea-chicken agro-forestry model in tropical area of China].

The N cycle of rubber-tea-chicken eco-agricultural model, a typical tropical agro-forestry system in Wenchang municipality of Hainan province, was studied with quantitative experiment and qualitative analysis, compared with rubber and rubeer-tea systems. The results showed that the N cycling rate, N output and soil surplus N of chicken garden were all the highest, being 43%; 196.5% kg.hm-2 and 237.6 kg.hm-2, respectively. The N output/input rate of chicken sub-system was 91%, and the transformation rate was very high. Compared with the other two systems, the chicken garden had a decreased external N input rate, and its internal cycling N was the highest, being 824.1 kg.hm-2. Rubber-tea-chicken agro-forestry system had a rational N cycling structure, and its N cycle was most active.

Animals↗
PubMed2000

[Coupling effect of water and fertilizers on spring wheat yield in semi-arid area of western Liaoning Province].

With optimum saturation design, a field experiment was conducted to study the coupling effect of water and fertilizers on spring wheat yield in semiarid area of western Liaoning Province. Regression model shows that water was the most important factor affecting spring wheat yield. Under natural raining and when the upper and the lower limit of irrigation was 360 mm and 45 mm, respectively, N was the most sensitive factor, water was the second, and P was the third. The effects of N, P and water on yield were statistically significant, and met the law of diminishing return. The most economic matching pattern of N, P and water was N 186 kg.hm-2, P 63 kg.hm-2, and water 300 mm. Properly increasing phosphorus fertilizer at the lack of water could strengthen the drought-resistance of spring wheat.

China↗
PubMed2000

[Artery denuded model and effects of three kinds of antisense c-myc RNA].

OBJECTIVE: To investigate the effects of antisense c-myc on injured vascular wall. METHODS: Three recombinant retroviral expression vectors, aM1, aM2 and aM3, which loading the reverse fragment of exon1, 2 and 3 respectively, were transferred into denuded rabbit femoral artery wall and were assayed 21 days after operation. RESULTS: (1) The regions of rabbit femoral artery were not only convenient for injury control, drug giving and material drawing, but also gave a neointimal area to media area vatio of 1.37:1. Their intensity and area of c-myc expression in media increased to 1.8 and 1.5 fold of normal value. (2) c-myc expression in aM2, aM3 and aM1 was reduced by 37.5%, 20.8%, and 17.8% with media intensity, 71.5%, 57.2%, and 61.6% with media area and 31.3%, 20.8%, and 17.8% with neointimal intensity respectively. (3) Neointimal area/media area of aM2 group reduced by 72.6%, aM3 group reduced by 35.2%, aM1 group had no significant difference comparing with control group. (4) Proliferating cellular nuclear antigen (PCNA) in the intimal and media of the three antisense transferred groups was enhanced with their expressive intensities, but reduced with expressive areas significantly. (5) With the declining of neointimal area/media area, alpha-SM actin expression in the intimal and media of the three antisense transferred groups was significantly increased (aM2 > aM3 > aM1). CONCLUSION: (1) Rabbit femoral artery denuded model is a satisfactory animal model. (2) Antisense c-myc transferring can reduce or resist the c-myc increase in injured artery wall, resist neointimal hyperplasia and smooth muscle cells dedifferentiation,especially c-myc exon 2 antisense RNA vector aM2.

Actins↗
PubMed2000

[Measurement of macrophage colony-stimulating factor during in-vitro fertilization and embryo transfer cycles].

OBJECTIVE: To explore the influences of macrophage colony-stimulating factor (M-CSF) on follicle development, ovulation, fertilization and embryo quality during in-vitro fertilization and embryo transfer (IVF-ET) cycles. METHODS: 36 patients underwent 54 cycles of controlled ovarian hyperstimulation by gonadotropin-releasing hormone agonist-human menopausal goudotropin-human chorionic gonadotropin for IVF-ET program. M-CSF concentrations in serum were measured at early follicular phase, mid-follicular phase and the day of oocyte retrieval by enzyme-linked immunosorbent assay. Follicular fluid (FF) on the day of egg retrieval was also measured for M-CSF concentration. RESULTS: M-CSF concentration in serum gradually increased throughout ovarian hyperstimulation and reached a peak on the day of oocyte retrieval. M-CSF concentration in FF was significantly higher than that in serum on the same day (P < 0.01). The M-CSF concentration in FF from follicles where oocytes could be retrieved, fertilized or with a diameter > or 16 mm, volume > or 2 ml, was significantly higher than those from follicles where oocyte could not be retrieved, fertilized or with a diameter < 16 mm, volume < 2 ml, respectively (P < 0.01). However, there was no significant difference in M-CSF concentration of FF between high and low embryo grade groups (P > 0.05). CONCLUSIONS: M-CSF may play an important role as an intraovarian regulator in the process of follicle development, maturation and ovulation. Therefore, M-CSF may exert an effect on fertilization process but not on the embryo quality.

Embryo Transfer↗
PubMed2000

[An observation of the immuno-persistence after inoculating with the domestic BRD II strain rubella vaccine among infants and young children].

OBJECTIVE: To study the immuno-persistence after inoculating with the domestic BRD II strain rubella vaccine among infants and young children. METHODS: Hemagglutination inhibition (HI) antibody detection method was used to test on children at age 6 to 18 months without rubella infection or rubella vaccine immunization in Yantai city of Shandong province and were selected for the observation of the immuno-persistence against the domestic BRD II strain rubella vaccine from 1995 to 1998. RESULTS: Positive rates of HI antibody among children of 6, 7, 8, 9, 12 and 18 month-old of inoculation were 94.44%, 97.22%, 96.67%, 100.00%, 100.00%, 100.00% and 93.10%, 93.55%, 96.77%, 96.97%, 100.00%, 100.00% (P > 0.05), in one or two years respectively. The geometric mean reverse titers (GMRTs) were about 50% lower than that after 1 month after 1 year. Similar results were found that after 2 years GMRTs was about 50% lower than that after 1 year of inoculation. There was highly significant difference on GMRTs of HI antibody between infants with 6 to 7 month-olds (29.89) and young children with 8 to 18 month-olds (53.00) after 2 years of inoculation (t = 3.58, P < 0.001). CONCLUSION: The immunization schedule at the first dose for BRD II strain rubella vaccine should be started when the child is 8 month old. For the second dose, the immunization schedule used in other developed countries should be referred adopted in China.

Antibodies, Viral↗
PubMed2000

[Changes of vWF in vascular endothelial cells with acute hypoxia].

OBJECTIVE: To investigate changes of vWF in vascular endothelial cells with acute hypoxia and assess its significance in the study of vascular injury and hypercoagulability. METHODS: vWF in vascular endothelial cells and in blood were measured by immunohistochemical staining image analysis and ELISA technique. Fibrin was displayed by phosphotungstic hematoxylin staining. RESULTS: The amount of vWF in vascular endothelial cells decreased progressively, while in blood increased progressively with hypoxia. Fibrin prominently increased with hypoxia. CONCLUSION: Acute hypoxia caused severe injury of vascular endothelial cells which resulted in release of vWF into blood from endothelial cells. The vWF amounts in blood may reflect the hypercoagulability, and may serve as a useful indicator of vascular injury and hypercoagulability.

Animals↗
PubMed2000

[Effect of exposure to low concentration of benzene and its analogues on luteal function of female workers].

The effect of benzene and its analogues(BIA) on the luteal function of female workers was studied in a petrochemical corporation. The female workers from a chemical fiber corporation without benzene exposure were selected as controls. The levels of BIA(toluene and xylene) in the air at breathing zone were sampled and determined with gas chromatography(GC). The menstrual function was followed up. Urine pregnanediol-3-glucuronide (PdG) and follicular stimulating hormone(FSH) were measured by enzyme immunoassay(EIA). The results showed that BIA existed in low concentration in air. The exposure could lead to a shorter length of time of luteal phase(P < 0.05 or P < 0.01) and decrease luteal progesterone level (P < 0.05). It was suggested that the low concentration of BIA exposure could have effect on the luteal function in exposed female workers, and urinary hormones could be used as biomarker for the influences of benzene and BIA on reproduction.

Adult↗
PubMed2000

Inhibitory effect of fluvastatin on aortic intimal thickening in normocholesterolemic rabbits.

OBJECTIVE: The anti-atherosclerotic effect of fluvastatin at does insufficient to lower serum cholesterol on the catheter-induced intimal thickering and possible mechanism were investigated in abdominal aorta of rabbits. METHODS: Fifty-six rabbits were randomly divided into eight groups (n = 7, each). Fluvastatin was given mixed with food at daily dose of 8 mg/kg starting 5 days before catheterization. Light microscope, immunohistochemistry, transmission electron microscope and RT-PCR assay were applied to assess vascular smooth muscle cell (VSMC) proliferation and apoptosis, as well as oncogene expression in vascular wall. RESULTS: At day 10 and day 15 after catheter induced denudation intima/media (I/M) thickness ratio was obviously higher, and also the percentage of PCNA-positive cells and TUNEL-positive cells in media was significantly higher compared with controls. The intimal hyperplasia was mostly composed of alpha-SM-actin-positive cells. In rabbits given fluvastatin I/M ratio and the percentage of these positive cells significantly decreased compared with those without fluvastatin. The overexpression of proto-oncogene H-ras mRNA and decreased expression of anti-oncogene p53 mRNA were found after vascular injury, whereas fluvastatin significantly reduced H-ras mRNA and increased p53 mRNA expression. CONCLUSION: Proliferation of VSMC in the media and the migration to the intima can be inhibited, and apoptosis of VSMC be induced by short-term use of fluvastatin after balloon catheter denudation, independent of serum lipid change. The underlying mechanism is presumably associated with the influence of fluvastatin on oncogene expression in the injured vascular wall.

Animals↗
PubMed1999

Conserved characteristics of heterochromatin-forming DNA at the 15q11-q13 imprinting center.

Nuclear matrix binding assays (NMBAs) define certain DNA sequences as matrix attachment regions (MARs), which often have cis-acting epigenetic regulatory functions. We used NMBAs to analyze the functionally important 15q11-q13 imprinting center (IC). We find that the IC is composed of an unusually high density of MARs, located in close proximity to the germ line elements that are proposed to direct imprint switching in this region. Moreover, we find that the organization of MARs is the same at the homologous mouse locus, despite extensive divergence of DNA sequence. MARs of this size are not usually associated with genes but rather with heterochromatin-forming areas of the genome. In contrast, the 15q11-q13 region contains multiple transcribed genes and is unusual for being subject to genomic imprinting, causing the maternal chromosome to be more transcriptionally silent, methylated, and late replicating than the paternal chromosome. We suggest that the extensive MAR sequences at the IC are organized as heterochromatin during oogenesis, an organization disrupted during spermatogenesis. Consistent with this model, multicolor fluorescence in situ hybridization to halo nuclei demonstrates a strong matrix association of the maternal IC, whereas the paternal IC is more decondensed, extending into the nuclear halo. This model also provides a mechanism for spreading of the imprinting signal, because heterochromatin at the IC on the maternal chromosome may exert a suppressive position effect in cis. We propose that the germ line elements at the 15q11-q13 IC mediate their effects through the candidate heterochromatin-forming DNA identified in this study.

Amino Acid Motifs↗
PubMed1999

Muscarinic receptor stimulation increases regulators of G-protein signaling 2 mRNA levels through a protein kinase C-dependent mechanism.

RGS2, a member of the Regulators of G-protein Signaling family, modulates the activity of G-proteins coupled to the phosphoinositide signal transduction system, but little is known about what regulates RGS2. In human neuroblastoma SH-SY5Y cells stimulation of muscarinic receptors by carbachol activates phosphoinositide signaling and also caused a rapid, large, and long lasting increase in RGS2 mRNA levels. Direct activation of protein kinase C also rapidly increased RGS2 mRNA levels. Inhibition of protein kinase C with Ro31-8220, GF109203x, or Go6976 or down-regulation of protein kinase C inhibited increases in RGS2 mRNA levels induced by carbachol or by the activation of protein kinase C. Blockade of calcium signaling did not alter carbachol-induced increases in RGS2 mRNA levels. Neither activation of epidermal growth factor receptors nor stimulation of cyclic AMP production with forskolin increased RGS2 mRNA levels. Pretreatment with actinomycin D blocked increases in RGS2 mRNA levels but caused a surprisingly small, although statistically significant, partial blockade of protein kinase C-mediated feedback inhibition of carbachol-induced phosphoinositide hydrolysis. Thus, RGS2 mRNA levels are increased by activation of muscarinic receptors coupled to the phosphoinositide signal transduction system through a protein kinase C-dependent mechanism. This action may contribute to negative feedback control of this signaling cascade, but because the small contribution to negative feedback contrasts with the large and prolonged elevations in RGS2 mRNA levels, we speculate that its primary role may be in modulating other signaling components.

Enzyme Inhibitors↗
PubMed1999

Permeate Flux in Crossflow Ultrafiltration under Intermediate Pressures.

The intermediate pressure range stands for an important condition for ultrafiltration operations where permeate flux falls below that predicted from a linear flux-pressure relationship but does not reach the limiting flux. Optimal performance of ultrafiltration might be achieved on the upper end of the intermediate pressure range because the maximum permeate flux will be obtained at the lowest possible pressure. Unlike in the low pressure range or in the high pressure range, little has been known about the behavior of permeate flux in the intermediate pressure range. A general theory of permeate flux in the intermediate pressure range is developed in this study. The theory includes the linear-increasing and limiting fluxes as two special cases and, therefore, can be used to study the behavior of permeate flux in ultrafiltration in the whole pressure range. Copyright 1999 Academic Press.

Journal Article↗
PubMed1999

Cloning and characterization of KCC3 and KCC4, new members of the cation-chloride cotransporter gene family.

The K+-Cl- cotransporters (KCCs) belong to the gene family of electroneutral cation-chloride cotransporters, which also includes two bumetanide-sensitive Na+-K+-2Cl- cotransporters and a thiazide-sensitive Na+-Cl- cotransporter. We have cloned cDNAs encoding mouse KCC3, human KCC3, and human KCC4, three new members of this gene family. The KCC3 and KCC4 cDNAs predict proteins of 1083 and 1150 amino acids, respectively. The KCC3 and KCC4 proteins are 65-71% identical to the previously characterized transporters KCC1 and KCC2, with which they share a predicted membrane topology. The four KCC proteins differ at amino acid residues within key transmembrane domains and in the distribution of putative phosphorylation sites within the amino- and carboxyl-terminal cytoplasmic domains. The expression of mouse KCC3 in Xenopus laevis oocytes reveals the expected functional characteristics of a K+Cl- cotransporter: Cl--dependent uptake of 86Rb+ which is strongly activated by cell swelling and weakly sensitive to furosemide. A direct functional comparison of mouse KCC3 to rabbit KCC1 indicates that KCC3 has a much greater volume sensitivity. The human KCC3 and KCC4 genes are located on chromosomes 5p15 and 15q14, respectively. Although widely expressed, KCC3 transcripts are the most abundant in heart and kidney, and KCC4 is expressed in muscle, brain, lung, heart, and kidney. The unexpected molecular heterogeneity of K+-Cl- cotransport has implications for the physiology and pathophysiology of a number of tissues.

Amino Acid Sequence↗
PubMed1999

Frequency of the fragile X syndrome in Chinese mentally retarded populations is similar to that in Caucasians.

Fragile X syndrome is recognized as the most common inherited cause of mental retardation in western countries. The prevalence of the fragile X syndrome in Asian populations is uncertain. We report a multi-institutional collaborative study of molecular screening for the fragile X syndrome from 1,127 Chinese mentally retarded (MR) individuals. We found that 2.8% of the Chinese MR population screened by DNA analysis had the fragile X full mutation. Our screening indicated that the fragile X syndrome prevalence was very close to that of Caucasian subjects. In addition, we found that 62.5% of fragile X chromosomes had a single haplotype for DXS548-FRAXAC1 (21-18 repeats) which was present in only 9.7% of controls. This unique distribution of microsatellite markers flanking the FMR1 CGG repeats suggests that the fragile X syndrome in Chinese populations, as in the Caucasian, may also be derived from founder chromosomes.

Alleles↗
PubMed1999

Lithium attenuates p53 levels in human neuroblastoma SH-SY5Y cells.

Lithium has neuroprotective effects in a number of model systems which may contribute to the therapeutic effects of lithium in mood disorders. Because the tumor suppressor p53 is linked to cell death, we tested whether lithium administration to human neuroblastoma SH-SY5Y cells modulated the activation of p53. After treatment of cells with H7 (25, 50, and 75 microM), nuclear p53 levels were increased to 464, 816 and 1079% of basal levels, respectively. A 24 h pretreatment with 5 mM lithium reduced these increases by 69, 61 and 28%, respectively. Pretreatment with 2 mM lithium for 1 or 14 days reduced the 25 microM H7-induced elevations of nuclear p53 by 40 and 70%, respectively, and even a 14-day pretreatment with 1 mM lithium caused a significant 16% reduction. Since increased nuclear p53 is a critical intermediate step in many signaling processes that culminate in cell death, attenuation of p53 activation by lithium reveals a mechanism by which lithium may support neuronal survival.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1999

Calpain inhibitor I increases beta-amyloid peptide production by inhibiting the degradation of the substrate of gamma-secretase. Evidence that substrate availability limits beta-amyloid peptide production.

The calpain inhibitor N-acetyl-leucyl-leucyl-norleucinal (ALLN) has been reported to have complex effects on the production of the beta-amyloid peptide (Abeta). In this study, the effects of ALLN on the processing of the amyloid precursor protein (APP) to Abeta were examined in 293 cells expressing APP or the C-terminal 100 amino acids of APP (C100). In cells expressing APP or low levels of C100, ALLN increased Abeta40 and Abeta42 secretion at low concentrations, decreased Abeta40 and Abeta42 secretion at high concentrations, and increased cellular levels of C100 in a concentration-dependent manner by inhibiting C100 degradation. Low concentrations of ALLN increased Abeta42 secretion more dramatically than Abeta40 secretion. ALLN treatment of cells expressing high levels of C100 did not alter cellular C100 levels and inhibited Abeta40 and Abeta42 secretion with similar IC50 values. These results suggest that C100 can be processed both by gamma-secretase and by a degradation pathway that is inhibited by low concentrations of ALLN. The data are consistent with inhibition of gamma-secretase by high concentrations of ALLN but do not support previous assertions that ALLN is a selective inhibitor of the gamma-secretase producing Abeta40. Rather, Abeta42 secretion may be more dependent on C100 substrate concentration than Abeta40 secretion.

Alzheimer Disease↗