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Biomedical subjects

L Liu

Publications and source records attributed to L Liu.

At least 1,099 records · Page 61Linked to original sources
PubMed1994

[Metabolism of propafenone and lidocaine in combination in rat liver supernatant].

Propafenone (Pro) and lidocaine (Lid) were incubated with rat liver supernatant and coenzyme factor. The competitive oxidations with each other were established. The original drug concentration of Pro and Lid were increased 0.7 and 0.5 times, respectively; and the metabolite dimethlglycinexylide (DGX) of Lid to be formed was decreased about 2/3 of that produced when administered alone. It was suggested that 1) they were metabolized by the same cytochrome P450 III A4 and the isozyme could be saturated, 2) the convulsive toxicity due to DGX will be decreased with its diminished formation, and 3) the combination of Lid and Pro would be beneficial for treatment of arrhythmias.

Animals↗
PubMed1994

[Effects of acupuncture on antral G cells in patients with gastric disease].

It is well known that acupuncture is effective for treatment of gastric disease in human. We have observed the effect of acupuncturing "Zhongwan" "Neiguan" "Zusanli" on fluorohistochemical changes of G cells of antral mucosa in 42 patients with gastric disease. The results show that after acupuncture treatment the amount of fluorescent G cells and the fluorescent intensity of gastrin in the G cells were obviously decreased in patients with duodenal ulcer, as compared with that before acupuncture treatment. However, the amount of G cells was increased by acupuncture treatment in patients with chronic atrophic gastritis. These data indicate the acupuncture may regulate G cell from abnormal to normal condition in gastric mucosa of gastric disease.

Acupuncture Therapy↗
PubMed1994

Motion sickness in mice and conditioned taste aversion.

Forty-eight male mice in 6 groups were studied. Conditioned taste aversion (CTA) in mice was produced by various motions including cross-coupled acceleration, rotation to two directions (with or without visual field) and linear acceleration. Deprived of water for 24 hours, the mice were exposed to motion immediately after drinking a novel solution, 0.15% saccharin. All groups received two pairings of CTA training related to motion. The results showed that both of cross-coupled and rotation produced frank CTA and former was far more obvious than the latter. In addition, motion with visual field had a trend to intensify sickness response.

Animals↗
PubMed1994

[Characteristics of reversed optic cupping in glaucoma after reduction of intraocular pressure].

Quigley's hypothesis indicates that the dense connective tissue is the least and the pores of the lamina cribrosa are the largest at the superior and inferior poles of the lamina cribrosa, therefore they are the most vulnerable locations to be involved by the characteristic glaucomatous optic nerve damage. To get clinical evidences of the hypothesis, the reversal or contraction of glaucomatous optic cup after reduction of intraocular pressure (IOP) was examined (The change is primarily caused by intraocular hypertension--induced distortion and posterior ectasia of the lamina cribrosa which moves forward reversely, leading to dilated optic cup contraction.). The method of examination was a stereoscopic flicker comparison with a computerized image system, alternatively displaying superposed 2 serial stereo pairs rapidly and the changing part presenting jumping appearance. Under stereoscopic observations, the changes of 3-dimension optic cup end be seen and the false positive phenomena caused by photographic angle variation, vascular pulsation, etc. can be differentiated from the characteristic changes of the cup. Stereo fundus photographs were taken from 31 eyes with high intraocular pressures before and after treatment for reduction of IOPs which was either diamox administration or trabeculectomy. The results show that the reversal of optic cups after reduction of IOPs are mostly asymmetrical, especially at the superior and/or inferior poles. By multiple stepwise regression, it is known that the amount of the change is only correlated with the initial IOP.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Impairment of macrophage eicosanoid and nitric oxide production by an alkaloid from Sinomenium acutum.

The effects of sinomenine (7,8-didehydro-4-hydroxy-3,7-dimethoxy-17-methyl- 9 alpha,13 alpha,14 alpha-morphinan-6-one), a pure alkaloid extracted from the Chinese medical plant Sinomenium acutum, on different macrophage capacities were investigated in vitro using resident mouse peritoneal macrophages and the macrophage-like cell line RAW 264.7. Sinomenine markedly decreased prostaglandin E2 and leukotriene C4 synthesis of macrophages stimulated by zymosan or calcium ionophore and also significantly inhibited the nitric oxide production of RAW 264.7 cells activated by interferon-gamma/lipopolysaccharide. It can be considered that these effects are part of the analgesic, anti-inflammatory, and antirheumatic mechanisms of sinomenine.

Alkaloids↗
PubMed1994

[Localization of GH gene to bovine chromosome 5q22-26 by in situ hybridization].

The bGH entire gene (3.0kb), as a probe which was cloned into recombinant plasmid pbGH was used for in situ hybridization. The E. coli RR1, as a receptor, was transformed by recombinant plasmid pbGH. Recombinant plasmid DNAs were amplified, extracted and purified, the bGH fragments were collected and labelled by nicktranslation. The metaphase and early-metaphase chromosome spreads were prepared from TdR-BrdU-synchronized peripheral blood lymphocytes in Beijing Black-white dairy cattle. After in situ hybridization and autoradiography, chromosomal G-bands were stained with FPG method. The number of silver grains on every chromosome was calculated. The result showed that bGH gene is located at chromosome 5q22-26. This assignment of the GH gene in cattle differs from those of previous assignments. Finally, the relationships between probe, mapping method and mapping accuracy were discussed.

Animals↗
PubMed1994

Molybdate depletes hepatic 3-phosphoadenosine 5-phosphosulfate and impairs the sulfation of acetaminophen in rats.

Molybdate (15 mmol/kg p.o.) decreased serum sulfate concentrations of rats 70% within 6 hr after administration. Parallel to this depletion, there was a dramatic decrease in hepatic sulfate and 3-phosphoadenosine 5-phosphosulfate (PAPS) concentrations (about 40 and 65%, respectively). However, renal PAPS concentrations did not change significantly. Molybdate reduced serum, hepatic and renal sulfate as well as hepatic PAPS concentration in a dose-dependent manner up to the dose of 10 mmol/kg. However, renal PAPS did not change. The results indicate that molybdate reduced not only sulfate concentrations in serum and tissue, but also PAPS concentrations in liver. The effect of molybdate on the pharmacokinetics of acetaminophen (AA, 150 mg/kg i.v.) was also investigated in order to determine whether molybdate-induced depletion of PAPS might be a useful tool for examining the importance of sulfation in the detoxication and toxication of xenobiotics. AA-sulfate concentration in blood decreased 40 and 80% after administration of molybdate at doses of 2.5 and 15 mmol/kg, respectively. Molybdate also decreased the excretion of AA-sulfate into bile and urine by about 60 and 80%, respectively. However, molybdate did not alter the excretion of AA-glucuronide and AA-glutathione/cysteine. The excretion of the parent AA increased 2-fold after molybdate administration (15 mmol/kg). In conclusion, molybdate effectively lowers inorganic sulfate in serum and tissues, and PAPS in the liver. Reduction of hepatic PAPS markedly decreases the sulfation of AA, suggesting that molybdate treatment could be used to study the importance of sulfation in pharmacology and toxicology.

Acetaminophen↗
PubMed1994

[Effects of stimulation of ventromedian area of nucleus hypoglossus on respiratory rhythm in rabbits].

The effects of electrical and chemical stimulation of ventromedian area of nucleus hypoglossus (VMNH) on the electrical activities of diaphragm and genioglossus were studied in 25 urethane-anesthetized, vagotomized rabbits. The experimental results were as follows: (1) A 6 s train of electrical stimulation caused a complete cessation of diaphragmatic activities and an excitation of genioglossal activities. (2) A 0.1 s train of stimulation of the nucleus during the middle or late inspiratory phase could elicit an inspiratory off-switch effect. (3) Microinjection of L-glutamate into VMNH also produced an inhibition of diaphragmatic activities. The above observations suggest that VMNH activity exerts a regulatory effect on respiratory rhythm, and this effect may be involved in the central mechanism of swallowing reflex.

Animals↗
PubMed1994

Molecular genetic analysis of oligodendroglial tumors shows preferential allelic deletions on 19q and 1p.

The molecular genetic alterations of oligodendroglial tumors and mixed gliomas of the central nervous system were studied in a series of 37 cases (8 oligodendrogliomas, 13 anaplastic oligodendrogliomas, 8 oligoastrocytomas, and 8 anaplastic oligoastrocytomas). A total of 180 polymorphic loci and 5 nonpolymorphic gene loci, distributed over all chromosomes, were examined by restriction fragment length polymorphism analysis. Loss of heterozygosity was most frequently observed for loci on 19q with a commonly deleted region at 19q13.2-q13.4 distal to the CYP2a gene and proximal to the D19S22 locus. The incidence of allelic loss on 19q was particularly high (81%) in oligodendroglial tumors and equal to 31% in mixed gliomas. More than 75% of the tumors with allelic deletions on 19q also showed loss of heterozygosity for loci on 1p with one tumor showing only loss of alleles distal to the NGFB gene (1p13-pter). Seven (19%) tumors had lost alleles from 17p with the deleted region including the TP53 tumor suppressor gene in all cases. Sequencing of the TP53 transcripts from exons 2 to 10, however, did not reveal mutations of the remaining allele in any of these tumors. Anaplastic oligodendrogliomas and anaplastic oligoastrocytomas demonstrated an increased incidence of additional allelic losses involving most frequently chromosomes 9p and 10. Gene amplification was detected in two anaplastic tumors, affecting the epidermal growth factor receptor gene in both cases, with additional amplification of the renin gene at 1q32 in one of these cases. In total our results indicate both differences and similarities between the molecular genetic alterations in tumors with oligodendroglial and astrocytic differentiation. The loss of genetic information from 19q and 1p as well as the rarity of TP53 mutations in oligodendroglial tumors suggests that the early events in their oncogenesis are distinct from those associated with astrocytic tumors. However, similarities are indicated by the allelic losses on 9p and 10 in the anaplastic tumors, suggesting the utilization of common pathways of progression.

Adolescent↗
PubMed1994

High-level expression of staphylococcal nuclease A in Escherichia coli.

The staphylococcal nuclease A gene has been successfully cloned and overexpressed in E. coli under the transcriptional control of the bacteriophage lambda PRPL promoters regulated by the temperature sensitive repressors. The SDS-PAGE analysis demonstrates that the nuclease A is produced to the extent of as much as 60% of the total cellular protein. The N-terminal analysis of the nuclease A shows that the amino terminal formyl methionine residue of the enzyme is precisely processed. The recombinant nuclease A with full activity is finally obtained after appropriate solubilization--denaturation and renaturation treatment. The conformational identity of the renatured nuclease A in different conditions is also studied by using hydrophobic interaction chromatography on a phenyl-superose HR5/5 column.

Base Sequence↗
PubMed1994

[Detection of human papillomavirus in cervical tissues using polymerase chain reaction].

Detection of human papillomavirus (HPV) 16 and 18 infection by polymerase chain reaction (PCR) was carried out in patients with normal cervix 53 cases, Chronic cervicitis with cervical erosion 59 cases, cervical cancer 12 cases, atypical hyperplasia 3 cases and condyloma acuminatum 2 cases. Results showed that a significantly higher detective rate of HPV-16 and 18 DNA in cervical cancer than in normal cervix, and a higher but not statistically significant positive rate than that in cervical erosion. It indicates that some cases of chronic cervicitis with HPV infection might develop into cervical carcinoma. This finding may help in the early discovery and prevention of cervical cancer.

Base Sequence↗
PubMed1994

Functional characterization of an EGF receptor with a truncated extracellular domain expressed in glioblastomas with EGFR gene amplification.

The most common type of alteration of the epidermal growth factor receptor gene (EGFR) in human glioblastomas results in the synthesis of an aberrant mRNA lacking 801 bases that encode amino acids 6-273 of the receptor's extracellular domain. To study the effects of this mutation on receptor function, we have developed chinese hamster ovary cell transfectants which express the mutant EGF receptor. Comparison of wild-type and mutant receptor properties in this cell host indicates that the truncated receptor does not bind EGF or TGF-alpha and, consequently, DNA synthesis is not stimulated in cultures of mutant transfectants by either grown factor. However, levels of DNA synthesis determined for mutant transfectants in serum-free media are several-fold higher than those determined for corresponding cultures of wild-type transfectants. Western blot analysis with anti-phosphotyrosine antibody indicates that the mutant receptor is constitutively phosphorylated in CHO cells, and the same analysis applied to lysates of glioblastoma biopsies reveals the altered receptor is readily detectable as a phosphotyrosine protein in tumors for which there is evidence of corresponding EGFR gene and transcript alterations. In total, these results indicate that the aberrant EGF receptor synthesized in glioblastomas, and which lacks a portion of the extracellular domain necessary for ligand binding, is an activated tyrosine kinase.

Animals↗
PubMed1994

Molecular cloning of the human CAK1 gene encoding a cyclin-dependent kinase-activating kinase.

Cyclin-dependent, proline-directed protein kinases normally function to execute critical cell cycle transitions; abnormal expression and/or viral subversion of the positive (cyclins) and negative (Pic1) regulatory subunits may contribute to neoplastic transformation and tumorigenesis. In addition to the binding of regulatory subunits, the enzymatic activities of the cyclin-dependent kinases, Cdc2 and Cdk2, are tightly regulated by site-specific protein phosphorylation events. Recent studies have identified a critical phosphorylation site (Thr-161) located within kinase Subdomain VIII that is necessary for Cdc2 activation, and enzymatic activities capable of carrying out this heterologous phosphorylation event have been detected in both Xenopus oocytes and human somatic cells. In this report, we characterize by molecular cloning a human homologue of the Xenopus Cdk-activating kinase (Cak, encoded by MO15); the novel human gene is designated (HS)CAK1. While only 75% identity is observed at the nucleotide level, the deduced amino acid sequence encoded by (HS)CAK1 is approximately 87% identical to that of the Xenopus MO15 gene in corresponding regions. The catalytic domain of (HS)Cak1, defined by conserved kinase Subdomains I through XI, exhibits considerable homology with (HS)Cdc2, suggesting that this kinase cascade involves closely related enzymes. Immunological studies with anti-Cak antibodies confirm the presence of specific immunoreactivity in highly purified preparations of the human Cdc2-activating kinase. The molecular characterization of (HS)CAK1 should facilitate studies of its physiological regulation, as well as its potential utility as a target for therapeutic intervention in the treatment of proliferative disorders.

Amino Acid Sequence↗
PubMed1993

Cloning a cDNA from human NK/T cells which codes for an unusual leucine zipper containing protein.

A 1724 base pair (bp) clone, B3-1, was obtained from a human NK subtracted cDNA library and sequenced. The cDNA encoded a 324 amino acid protein with a calculated molecular mass of 36 kDa. The deduced protein did not contain any hydrophobic domains, suggesting that it was not secreted or membrane bound. Extensive database searches showed no significant overall homology to any known proteins or genes. The protein did, however, contain an unusually long (twice normal) leucine zipper and the nuclear targeting sequence found in many transcription factors and oncogenes. The cDNA also contained three repeats of the sequence 'ATTTA' in its 3' untranslated region, a motif associated with many oncogenes, transcription factors and interleukins. The mRNA for this gene is weakly expressed in resting NK/T cells.

Amino Acid Sequence↗