[Observation on pollen morphology of six species of Typha (Puhuang) by SEM].
The pollens of 6 species of Typha (Puhuang) have been observed by SEM. The morphological characters of the pollens are described.
Microscopy, Electron, Scanning↗
Biomedical subjects
B Liu
Publications and source records attributed to B Liu.
[Determination of pseudouridine in serum by high performance liquid chromatography].
Pseudouridine is a modified nucleoside derived from the degradation of transfer ribonucleic acid. The elevation of modified nucleosides in urine has been suggested to be caused by higher turnover rate of t-RNA in tumor tissue than in healthy tissue, rather than by cell death. A method of pseudouridine determination in serum was developed by high-performance liquid chromatography on a Nova-Pak column (Waters) with 0.04 mol/L KH2PO4 (pH 4.0) as mobile phase. The blood samples were collected and 0.6 mL of serum was treated with 0.4 mL 6% HClO4. The precipitate was centrifuged for 10 min at 3000 r/min. Five-hundred microL of the liquor was dried by air-stream at 60 degrees C. The residue was dissolved with 300 microL mobile phase and 10 microL was injected. The average recovery was 93.50 +/- 2.1%. The calibration curve was linear within the concentration range of 0.7-6.8 micromol/L. The serum pseudouridine concentrations for patients with hepatitis, lung cancer, nephritis and uremia were determined and those of patients with lung cancer and uremia were found significantly higher than those of healthy controls (p<0.05). And for patients treated with He-Ne laser no significant change of the pseudouridine hasn't been found (p<0.05).
Adolescent↗
SnoRNAs as tools for RNA cleavage and modification.
Eukaryotic small nucleolar RNAs (snoRNAs) influence rRNA synthesis at two stages: nucleolytic processing and selection of nucleotides to be ribose methylated (Nm) or converted to pseudouridine (psi). The two modification functions and some processing activities involve direct base pairing of snoRNA with rRNA. In addition to rRNA-targeting sequences, snoRNA function depends on the presence of conserved box elements involved in snoRNA synthesis and localization. The present investigation is directed at using snoRNAs as tools for two purposes: 1) introducing nucleotide modifications into novel sites in rRNA and other snoRNAs, and: 2) targeting nucleolar RNAs for destruction using snoRNA:ribozyme chimers ('snorbozymes'). Early results demonstrate that snoRNAs can be used for both applications.
Cell Nucleolus↗
12(S)-HETE increases the motility of prostate tumor cells through selective activation of PKC alpha.
Prostate carcinoma has become the second most fatal cancer in American men. In rat Dunning prostate adenocarcinoma cells, increased cellular motility has been associated positively with their increased metastatic potential. However, the mechanism(s) responsible for regulation of tumor cell motility is poorly understood. We have reported that a lipoxygenase metabolite of arachidonic acid 12(S)-hydroxyeicosatetraenoic acid [12(S)-HETE] augments tumor cell metastatic potential through activation of protein kinase C (PKC). We report here that 12(S)-HETE increased the motility of AT2.1 cells and this 12(S)-HETE increased motility was inhibited by PKC inhibitor calphostin C. Western blot analysis revealed that AT2.1 cells expressed the Ca(2+)-dependent PKC isoform alpha and Ca(2+)-independent PKC isoform delta. Pretreatment of cells with a Ca2+ chelator BAPTA blocked the 12(S)-HETE increased motility. Further, the motility of AT2.1 cells was increased in a dose dependent manner by thymelea toxin, a selective PKC alpha activator. Our data demonstrate that 12(S)-HETE augments the motility of AT2.1 cells via its selective activation of PKC alpha which may serve as a key target for the development of antimetastatic drugs useful for combating prostate cancers.
12-Hydroxy-5,8,10,14-eicosatetraenoic Acid↗
[Searching for retroviral sequences related to human breast cancer].
The participation of viruses in mammary carcinogenesis has been largely studied in animals. A model similar to the mouse mammary tumor virus (MMTV) was previously proposed. Several lines of research supported the participation of MMTV in human breast cancer, but these evidences were contradicted when further research was performed. One major issue was the presence of human endogenous retroviral sequences that confounded results reporting MMTV-like sequences in human breast cancer. To overcome this problem we selected a 660 bp sequence of the MMTV env gene with low homology to endogenous sequences and search for a sequence to it using the polymerase chain reaction (PCR). The sequence was found in 38% of the human breast cancers and in 2% of the normal breasts studied. The sequence was not present in tumors from other organs. It was 90-98% homologous to MMTV and only 18% to human endogenous retrovirus (HERV) K-10. It was also detected in some of the positive tumors by Southern blot hybridization using one of the cloned 660 bp as a probe. Using reverse transcriptase PCR, it was possible to demonstrate that the 660 bp sequence is expressed in the majority of the tumors. Also, preliminary experiments revealed that sequences related to the LTR and gag genes of MMTV were present in the DNA of breast tumors. The origin of the MMTV-like sequences in tumor DNA could be the result of integrated MMTV-like sequences derived from a human mammary virus or may represent unknown endogenous sequences that can only be detected in breast tumors.
Animals↗
Otoacoustic emission and auditory efferent function testing in patients with sensori-neural hearing loss.
OBJECTIVE: To examine the role of otoacoustic emissions and auditory efferent system function in evaluating auditory functional status in both normal and diseased conditions. METHODS: Spontaneous and transient evoked otoacoustic emissions and efferent function in terms of contralateral white noise induced transient evoked otoacoustic emission suppressions were tested and cross compared in 32 normal ears, 24 ears with cochlear hearing loss and 16 ears with retrocochlear hearing loss. RESULTS: Transient evoked otoacoustic emission amplitude and contralateral suppression, spontaneous otoacoustic emission incidence, peaks and frequency range were significantly reduced in cochlear hearing loss while in retrocochlear hearing loss transient evoked otoacoustic emission and spontaneous otoacoustic emission levels were significantly higher than in cochlear hearing loss group and showed no suppression. CONCLUSIONS: Contralateral acoustic stimulation induced transient evoked otoacoustic emission suppression as an index of efferent function is clinically feasible. Combined otoacoustic emission and efferent tests are of great significance in evaluating cochlea status and auditory central mechanisms. Auditory efferent function is weakened in cochlear lesions and severely damaged in retrocochlear lesions.
Adolescent↗
[Distribution and significance of endothelin-1 and endothelin receptor a mRNA in liver after endotoxemia].
OBJECTIVE: To study the distribution and significance of endothelin-1 (ET-1) and endothelin receptor A (ETAR) mRNA in liver after endotoxemia using situ hybridization. METHODS: 30 rats were randomized into control and endotoxin groups. The endotoxin group was injected with endotoxin at a dose of 10 mg/kg body wt. Hybridization of ET-1 and ETAR mRNA of the hepatic tissue was proceeded at 3, 6, 12 and 24 hours after endotoxin administration. RESULTS: By in situ hybridization, the cell expression of ET-1 mRNA was hepatic sinusoids, the endothelial cells of portal vein, and Kupffer cell and the cell expression of ETAR mRNA was the small artery smooth muscle cells of hepatic lobule and the hepatic sinusoidal lining cells. The accumulation of grain was observed in many cells of the liver. The number of accumulating grain increased in unit scope. CONCLUSION: ET-1 is synthesized by the hepatic sinusoids, hepatic vascular endothelial cells, and Kupffer cells, ETAR may be located on the hepatic vascular smooth muscle cells and Ito cells (fat-storing cells) around sinusoid. Endotoxin may, on transcription and translation level, lead to the increase of ET-1 and ETAR in synthesis and release.
Animals↗
[Detecting pathogens of fetal defects in paraffin embedded tissues by polymerase chain reaction].
OBJECTIVE: To examine 3 types of pathogens in dead fetus with congenital defects for exploring the pathogenesis. METHODS: The paraffin embeded brain and liver tissues from 39 fetal autopsies with congenital defects were examined for toxoplasma, cytomegalovirus, and herpes simplex II by polymerase chain reaction. Among them 16 placentae were examined as well. RESULTS: Pathogens were detected in 25 of 39 cases, a positive rate of 64%. Nine out of the 13 fetuses with urogenital defects were positive for the shove pathogens, while 8 from the 12 with neural tube defects were positive as well. CONCLUSION: Intrauterine infection was one of the important causes of birth defects. The characteristics of placenta morphologic changes were described, and the significance of placenta investigation in congenital malformation was emphasized.
Animals↗
Expression and cellular location of endothelin-1 mRNA in rat liver following endotoxemia.
OBJECTIVE: To study the effect of endotoxin on the alteration of the transcription, expression and cellular location of endothelin-1 (ET-1) mRNA in the hepatic tissue. METHODS: Wistar rats were divided into control and endotoxic group. The rats in the control group were injected with saline, and those in the endotoxic group with endotoxin at a dose of 10 mg.kg-1 body wt. ET-1 hepatic homogenate was assayed by radioimmunoassay at 3, 6, 9, 12 and 24 h after endotoxin administration. Dot blot was used to identify and quantify ET-1 mRNA of the hepatic tissue. Hybridization of ET-1 of the hepatic tissue was proceeded at 3, 6, 12 and 24 h after endotoxin administration. RESULTS: ET-1 concentrations and the level of ET-1 mRNA increased rapidly and reached the peak at 6 h, and remained high at 24 h after endotoxin administration. By in situ hybridization, ET-1 mRNA was found in hepatic sinusoids, endothelial cells of portal vein and kupffer cells. CONCLUSIONS: Endotoxin may be the principal stimulating factor for expression of ET-1 mRNA in hepatic tissue. Endotoxin may affect transcription and translation level of ET-1, leading to increase of the synthesis and release of ET-1. The hepatic vascular endothelial cells, hepatic sinusoids and Kupffer cells all synthesize and release ET-1.
Animals↗
[Detection of p53 gene mutation in paraffin-embedded asbestos-related lung cancer tissue].
Paraffin-embedded asbestos-related lung cancer tissue of ten cases was analyzed with polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) to study its genetic mutation of exon 5, 7 and 8 of anti-oncogene p53 by silver stain. Results showed that fragment of exon 7 or 8 of p53 gene in four cases was positive in silver-staining analysis of PCR-SSCP. Exon 7 or 8 fragments of p53 gene was detected positive for mutation in seven of these ten cases with autoradiographic analysis of PCR-SSCP. No exon 5 fragment was found positive for mutation in these ten cases with both methods. Agreement between results of silver staining and those of autoradiographic PCR-SSCP was 60%. Hence, autoradiographic method could be replaced by silver staining, a simpler and more sensitive one, in PCR-SSCP to study gene mutation of asbestosrelated lung cancer.
Adenocarcinoma↗
[A preliminary study on p53 gene in lung cancer tissues of workers exposed to silica and welding fumes].
Mutations of suppressor gene p53 was studied in 36 cases of silica related lung cancer and 6 cases of welding fume related lung cancer with immunohistochemical and PCR-SSCP methods. Cancer tissues were embedded in paraffin and stored for 13.4 years in average. Results revealed that there was abnormal mobility shift of electrophoresis in 18 cases with 20 point mutations of 42 specimens tested, accounted for 42.9%, and 50% (10/20) of the mutations were clustered in exon 8. This finding differed from mutational spectrum of gene in non-occupational lung cancer, in which mutation frequency of exon 8 ranged from 17.5% to 23.5%. Gene mutation frequency in varied pathological categories of pneumoconiosis related lung cancer also differed from that in common lung cancer. In the latter, the highest one was in small cell lung cancer (70%) and the lowest in adenocarcinoma (33%), but in the former, the highest in adenocarcinoma (53.9%) and the lowest in small cell lung cancer (30.8%). Immunohistochemical observations also showed a very high prevalence of p53 gene mutation expression (46.9%). Sequencing, which was determined in two cases of this study, revealed that two point mutations all occurred in non-hotspot codon 144 of p53 gene. Difference in gene mutation spectrum suggests that there exist specific carcinogens and carcinogenesis in silica and welding fume related lung cancer.
Adenocarcinoma↗
[Evaluation of the methods of bone age determination in children].
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Age Determination by Skeleton↗
[Effect of puerarin on plasma endothelin, renin activity and angiotensin II in patients with acute myocardial infarction].
OBJECTIVE: To study the changes of endothelin (ET), renin activity (RA) and angiotensin II (AT-II) before and after puerarin treatment in patients with acute myocardial infarction (AMI). METHODS: Forty-three patients with AMI were divided into two groups, and were given puerarin and glucose-insulin-kalium (GIK) treatment respectively. Plasma ET, RA and AT-II were measured by radioimmunoassay (RIA) before and after treatment in different phases. RESULTS: It showed that plasma ET and RA, AT-II levels in AMI were higher than those in control group (P < 0.01). ET level was conversely correlated with RA and AT-II (P < 0.01). After treatment with puerarin, plasma levels of ET, RA and AT-II were recovered to normal in 3 days, but these data recovered to nearly normal until 7-14 days in group with GIK treatment. CONCLUSION: Puerarin might play an important role in regulating the imbalance of ET, RA and AT-II of patients with AMI.
Aged↗
[Experimental study of coral implantation in repair of skull bone defect in rabbit: histomorphometry of bone].
In order to evaluate coral as a bone graft substitute in repair of bone defect, particulates of coral were implanted into skull bone defect of rabbit, 1.5 cm in diameter. Hydroxyapatite and blank were taken as controls. The rabbits were sacrificed at the second, fourth, eighth and twelveth weeks after the operation. The specimens were taken and performed histological examination and histomorphometry observation. Results were as follows: at the second week many multinucleus giant cells infiltrated. As time elapsed, the coral were progressively degenerated and new bone was formed to fill the defect. Up to the twelveth week, the coral degenerated completely and new bone formed in the center of the defect. Percentage of new bone was in defect was 36.9%. Compared with the controls, there were significant differences (P < 0.01). It was suggested that coral had good osteoconductility. Howevel, coral underwent rapid degeneration, it might result in inconplete repair of bone defect.
Animals↗
[A study of anaerobic infection in maxillofacial region].
To analyse the anaerobic infection of maxillofacial surgery and estimate the efficacy of antianaerobic therapy, 45 patients were divided into two groups, tinidazole group and metronidazole group. Bacterial culture was positive before treating in all cases. There were Bacillus Melaniogenicus, Veillonella, Peptococcus and Peptostreptococus, etc. There was excellent efficacy in the treatment of maxillofacial anaerobic infection by tinidazole intravenously. After treatment, the result of bacterial examination was negative. The healing rate was 96.4% in 28 cases which used tinidazol, but 82.4% in control group which used metronidazole. The value of white blood cell and the function of liver and kidney pro- and post-treatment were not significantly different (P < 0.05) by comparision.
Adolescent↗
Repression of platelet-derived growth factor A-chain gene transcription by an upstream silencer element. Participation by sequence-specific single-stranded DNA-binding proteins.
Platelet-derived growth factor A-chain is a potent mitogen expressed in a restricted number of normal and transformed cells. Transient transfection and deletion analysis in BSC-1 (African green monkey, renal epithelial) cells revealed that the -1680 to -1374 region of the A-chain gene repressed homologous and heterologous promoter activities by 60-80%. An S1 nuclease-hypersensitive region (5'SHS) was identified within this region (-1418 to -1388) that exhibited transcriptional silencer activity in BSC-1 and a variety of human tumor cell lines (U87, HepG2, and HeLa). Electrophoretic mobility shift assays conducted with 5'SHS oligodeoxynucleotide probes revealed several binding protein complexes that displayed unique preferences for binding to sense, antisense, and double-stranded forms of the element. Southwestern blot analysis revealed that the antisense strand of 5'SHS binds to nuclear proteins of molecular mass 97, 87, 44, and 17 kDa, whereas the double-stranded form of 5'SHS is recognized by a 70-kDa factor. Mutations within 5'SHS element indicated the necessity of a central 5'-GGGGAGGGGG-3' motif for protein binding and silencer function, while nucleotides flanking both sides of the motif were also critical for repression. These results support a model in which silencer function of 5'SHS is mediated by antisense strand binding proteins, possibly by stabilizing single-stranded DNA conformations required for interaction with enhancer sequences in the proximal promoter region of the A-chain gene.
Base Sequence↗
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↗
Molecular characterization of a positively photoregulated nuclear gene for a chloroplast RNA polymerase sigma factor in Cyanidium caldarium.
We have cloned the gene for a putative chloroplast RNA polymerase sigma factor from the unicellular rhodophyte Cyanidium caldarium. This gene contains an open reading frame encoding a protein of 609 amino acids with domains highly homologous to all four conserved regions found in bacterial and cyanobacterial sigma 70-type subunits. When Southern blots of genomic DNA were hybridized to the "rpoD box" oligonucleotide probe, up to six hybridizing hands were observed. Transcripts of the sigma factor gene were undetectable in RNA from dark-grown cells but were abundant in the poly(A)+ fraction of RNA from illuminated cells. The sigma factor gene was expressed in Escherichia coli, and antibodies against the expressed sigma factor fusion protein cross-reacted with a 55-kDa protein in partially purified chloroplast RNA polymerase. Antibodies directed against a cyanobacterial RNA polymerase sigma factor also cross-reacted with a 55-kDa protein in the same enzyme preparation. Immunoprecipitation experiments showed that this enzyme preparation contains proteins with the same molecular weights as the alpha, beta, beta', and beta" subunits of chloroplast RNA polymerase in higher plants. This study identifies a gene for a plastid RNA polymerase sigma factor and indicates that there may be a family of nuclear-encoded sigma factors that recognize promoters in subsets of plastid genes and regulate differential gene expression at the transcriptional level.
Amino Acid Sequence↗