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Biomedical subjects

G Liu

Publications and source records attributed to G Liu.

At least 487 records · Page 27Linked to original sources
PubMed1996

Effect of macromolecular-translocation inhibitor-III on binding of activated glucocorticoid-receptor complex to specific DNA.

We previously purified macromolecular-translocation inhibitor-III (MTI-III), which inhibits the binding of the activated glucocorticoid-receptor complex (GR) to nuclei, to homogeneity from rat liver, and we found that the purified MTI-III bound to partially purified activated GR under low salt conditions at slightly acidic pH [Liu, G., Okamoto, K., and Isohashi, F. (1993) Eur. J. Biochem. 218, 679-687]. This was the first direct evidence that the inhibitor acts through a direct interaction with the activated GR. In this study, we examined whether the purified MTI-III could interfere with the binding of GR to a DNA fragment containing a specific glucocorticoid-response element (GRE). Under nearly isotonic salt conditions at neutral pH, the activated GR bound to the GRE but not to nonspecific DNA. Under similar conditions, the activated GR also bound to the purified MTI-III. The resulting GR/MTI-III complex did not bind to the GRE. We also found that addition of MTI-III to the GR/GRE complex resulted in time-dependent disruption of the GR/GRE complex and formation of the GR/MTI-III complex. The half-life of the GR/GRE complex in the presence of MTI-III was about 13 min. These results suggest that MTI-III enhances the release of GR from the GR/GRE complex and immediately forms a stable GR/MTI-III complex.

Animals↗
PubMed1996

Increased myosin light chain kinase content in sensitized canine saphenous vein.

Our previous studies revealed that smooth muscle from sensitized canine saphenous vein (SCSV) demonstrated greater active shortening capacity, maximum shortening velocity, and prolonged relaxation vis-a-vis the control muscle. These changes could be responsible for the in vivo hyperreactivity of venous smooth muscle observed in anaphylactic shock. Because smooth muscle cross-bridge cycling is regulated by myosin light chain kinase (MLCK)-dependent phosphorylation of the 20-kDa myosin light chain (MLC20), we studied MLC20 and MLCK phosphorylation in homogenates of SCSV and veins from littermate control dogs. We found that phosphorylation of MLC20 in SCSV homogenate was higher (42.26 +/- 5.10%) compared with control homogenates (26.69 +/- 3.30%; P < 0.05); MLCK content was significantly higher in SCSV homogenates [0.169 +/- 0.019 (SE) mu g/mg protein] than in control homogenates (0.075 +/- 0.004 mu g/mg protein; P < 0.05). Total MLCK activity increased from 6.16 +/- 0.60 x 10(-5) nmol Pi x mg fresh weight of tissue-1 x min-1 in control homogenates to 12.50 +/- 2.50 x 10(-5) nmol Pi x mg fresh weight of tissue-1 x min-1 in sensitized homogenates (P < 0.05). Specific MLCK activity was, however, similar in sensitized and control homogenates. The results of our study suggest that elevation of MLCK content in the homogenate could account for the increased contractility of the SCSV in anaphylactic shock.

Animals↗
PubMed1996

Prospective comparison of the sclerosing agents doxycycline and bleomycin for the primary management of malignant pericardial effusion and cardiac tamponade.

PURPOSE: To compare the clinical efficacy and toxicity of doxycycline and bleomycin as sclerosing agents in the primary management of malignant pericardial effusion (MPE). METHODS: Twenty-seven consecutive adult patients referred to a tertiary-care institution for the management of cardiac tamponade and malignancy underwent pericardial drainage through a percutaneously placed pigtail catheter. They were then alternately assigned to undergo bleomycin or doxycycline pericardial sclerosis. RESULTS: There were 13 men and 14 women, with a median age of 59 years. They mainly had lung (70%) and breast cancers (11%), and all had clinical and echocardiographic evidence of cardiac tamponade. Although all patients had successfully placed catheters, six were inadvertently dislodged before sclerosis; 11 underwent bleomycin sclerosis and 10 doxycycline sclerosis. Twenty patients (one early death) were assessable. One patient in each group failed to respond to sclerosis with the initial agent, but both were sclerosed successfully with the other agent. Sclerosis was achieved with a median of two instillations for each agent and total median doses of bleomycin 20 mg and doxycycline 1,250 mg. Seventy percent of doxycycline patients developed significant retrosternal pain, compared with no bleomycin patients (P = .04). Doxycycline patients required a median of 3.5 more days of hospitalization (8.5 v 5) and 2 more days of pericardial catheterization (7 v 5) compared with bleomycin patients. Tamponade recurred in one bleomycin patient at 253 days, and in no doxycycline patient. CONCLUSION: Although bleomycin and doxycycline are equally effective sclerosing agents, bleomycin is associated with significantly less morbidity and should be the first-line chemical sclerosing agent for malignant pericardial effusions.

Adult↗
PubMed1996

TGF-beta 1 inhibits the cell proliferation stimulated by IGF-I by blocking the tyrosine phosphorylation of 175kDa substrate.

TGF-beta strongly inhibits the mitogenic effect of growth factors such as insulin-like growth-I (IGF-I) on thyroid follicular cells. To study the mechanism of this inhibiting action, the effect of TGF-beta 1 on tyrosine phosphorylation of 175kDa substrate induced by IGF-I was investigated in FRTL-5 thyroid epithelial cells. After treatment with TGF-beta 1, tyrosine phosphorylation of 175kDa protein induced by IGF-I was inhibited in parallel with the degree of the inhibition of cell proliferation. However, TGF-beta 1 had no effect on tyrosine phosphorylation of 120kDa substrate. These results suggest that TGF-beta 1 blocks the mitogenic signal of IGF-I by inhibiting the tyrosine phosphorylation of 175kDa substrate in FRTL-5 cells.

Animals↗
PubMed1996

[Role of nitric oxide in immunological liver injury in mice].

OBJECTIVE: To study the role of nitric oxide (NO) in mouse immunological liver injury. METHODS: Injection of either bacille calmette guréin (BCG) or lipopolysaccharide (LPS) alone in mice was used to induce moderate increase of plasma NO level and liver damage were seen after the RESULTS: Administration of LPS following BCG injection resulted in remarkable elevation of plasma NO level and severe liver damage. The elevation of NO level and liver damage induced by BCG or BCG + LPS were not affected by administration of L-arginine, and substrate of NO synthase. Inhibition of NO synthase by NG-monomethyl-arginine (NMMA) decreased the elevated plasma NO without effect on the elevated plasma GPT and GOT levels induced by BCG injection. The BCG + LPS induced elevation of plasma GPT and GOT levels were more pronounced after NO production was inhibited by NMMA treatment. The action of NMMA mentioned above was partially reversed by simultaneous administration of L-arginine. CONCLUSION: NO plays a protective action against liver injury induced by BCG + LPS in mice.

Animals↗
PubMed1996

Database cloning human delta 1-pyrroline-5-carboxylate synthetase (P5CS) cDNA: a bifunctional enzyme catalyzing the first 2 steps in proline biosynthesis.

delta 1-pyrroline-5-carboxylate synthetase (P5CS) catalyzes the ATP and the NAD(P)H-dependent conversion of L-glutamate to glutamic gamma-semialdehyde (GSA) which is the metabolic precursor for proline biosynthesis. We cloned a human P5CS cDNA by database cloning strategy and sequenced 2,907 bp from this cDNA which has a closed open reading frame (ORF) of 2,385 bp coding for a polypeptide of 795 amino acid residues. This cDNA, as its plant counterpart, encodes a bifunctional enzyme, with both gamma-glutamyl kinase (gamma-GK) and gamma-glutamyl phosphate reductase (gamma-GPR) activities that catalyzes the first 2 steps in proline biosynthesis and it hybridizes to a 4.5 kb mRNA from various tissues. A human genetic disease caused by a deficient P5CS has been recognized. The phenotypic features for deficiency of P5CS include joint hyperlaxity, skin hyperelasticity, cataract and mental retardation with hyperammonemia and low plasma levels of proline, citrulline and ornithine.

1-Pyrroline-5-Carboxylate Dehydrogenase↗
PubMed1996

17 beta-estradiol inhibits proliferation and migration of human vascular smooth muscle cells: similar effects in cells from postmenopausal females and in males.

OBJECTIVES: Cardiovascular disease is rare in premenopausal women, but increases after the menopause when hormone replacement therapy reduces coronary events. Vascular smooth muscle cell (SMC) proliferation and migration occur in atherosclerosis, restenosis and venous graft disease. We studied the effects of 17 beta-estradiol on SMC proliferation and migration. METHODS: SMC were cultured from saphenous veins of postmenopausal women and age-matched men. Cell growth was determined by 3H-thymidine incorporation and cell counting. Migration of SMC was assessed in 4-well chambers. SMC were seeded in one corner and PDGF-BB in filter paper glued onto the opposite wall. RESULTS: PDGF-BB (5 ng/ml for 24 h) similarly stimulated 3H-thymidine incorporation in female (511 +/- 57%; n = 8) and male (528 +/- 62%; n = 12) SMC. This was reduced by 17 beta-estradiol (10(-8)-10(-6) M; female 313 +/- 52%; male 337 +/- 54%; P < 0.05). PDGF-BB increased the number of SMC (P < 0.0001 at 10 days) obtained from females (153 +/- 3%; n = 5) and males (150 +/- 4%; n = 5), which was inhibited by 17 beta-estradiol (10(-6) M; female 134 +/- 7%; male 128 +/- 5%; P < 0.05). Similar results were obtained with basic fibroblast growth factor. In contrast to 17 beta-estradiol, another steroid (dexamethasone) had no effects on 3H-thymidine incorporation in these cells stimulated with PDGF-BB, PDGF-BB (0.01-1 ng) stimulated SMC migration (P < 0.05) which was inhibited by 17 beta-estradiol (10(-10)-10(-6) M; n = 5; P < 0.005). CONCLUSION: 17 beta-Estradiol inhibits growth-factor-induced SMC proliferation and migration regardless of gender. These effects of 17 beta-estradiol may contribute to its cardiovascular protective properties in postmenopausal women during replacement therapy.

Aged↗
PubMed1996

[Analysis of the A/C polymorphic site within the phenylalanine hydroxylase gene].

An A/C polymorphism was identified at nucleotide-11 from the acceptor site of IVS3 of the phenylalanine hydroxylase gene. This polymorphism can be detected easily by means of single strand conformation polymorphism analysis. The frequency for the majior allele (A) was 0.656 and 0.344 for the minor allele (C) with the PIC being 0.351 in Chinese population. There was no linkage disequilibrium between this site and the STR polymorphic site located upstream within the same intron of the gene. The ejjicincy of prenatal gene diagnosis fro PKU was estimated to be 78.1% by haplotype linkage analysis using these two polymorphic sits.

Humans↗
PubMed1996

Genotyping of ABO blood group system by PCR and RFLP on mummies discovered at Taklamakan desert in 1912.

ABO genotyping was carried out using polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP) method on the dried remains of nine human mummies which had been discovered at Taklamakan desert in 1912. In all the nine mummies, ABO genotype could be determined as BO type, and ABO phenotype of the eight mummies with hair specimen could be revealed as B type using absorption-elution method. These results mean that ABO phenotype estimated from its genotype by PCR-RFLP was consistent with that by absorption-elution method in all of the eight cases examined. And in the other one child mummy, ABO phenotype could not be examined because of no hair specimen. Although it is impossible to assess the allele frequency of ABO blood group system in the populations having lived in Gao Chang at that time, the present study shows a possibility of ABO genotyping from ancient human remains.

ABO Blood-Group System↗
PubMed1996

Long-term blood pressure control in older Chinese patients with isolated systolic hypertension: a progress report on the Syst-China trial.

This report on the ongoing double-blind placebo-controlled Syst-China trial investigated whether antihypertensive drug treatment based mainly on a calcium entry blocker and a converting enzyme inhibitor, would be suitable for maintaining long-term blood pressure (BP) control in older Chinese patients (average age: 67 years) with isolated systolic hypertension (systolic pressure 160-219 mm Hg and diastolic pressure < 95 mm Hg). Active treatment consisted of nitrendipine (10- 40 mg/day) with the possible addition of captopril (12.5- 50 mg/day) and hydrochlorothiazide (12.5-50 mg/day), as necessary to reduce systolic pressure to a level of 150 mm Hg or lower and by at least 20 mm Hg. Matching placebos were used in the control group. This progress analysis was restricted to BP control up to 3 years of follow-up. The placebo (n = 1134) and active treatment n = 1245) groups had similar characteristics at enrolment. The sitting BP averaged 170/86 mm Hg. Systolic pressure fell (P < 0.001) on average 8 mm Hg more on active treatment than on placebo and diastolic pressure 3 mm Hg more. Fewer patients remained on monotherapy in the placebo than in the active treatment group (P < 0.001); on placebo the second and third line medications were started more frequently (P < 0.001). This progress report showed that significant BP reduction can be achieved and maintained in older Chinese patients treated with a calcium antagonist, associated with a converting-enzyme inhibitor and a thiazide, as necessary. Whether this BP reduction would result in a clinically meaningful decrease of cardiovascular complications is still under investigation.

Aged↗
PubMed1996

[Ribozyme targeted the point-mutation of activated oncogene inhibits its expression in vivo].

We demonstrated previously that the hammerhead ribozyme designed by us against the activated oncogene T24-ras cleaved the target mRNA specifically and efficiently in vitro. To study its properties in vivo, we cloned the DNA fragment encoding the ribozyme into the eukaryotic expression vector pSMG and transfected it into the T24-ras gene transformed NIH3T3 cell lines. The intracellular cleavage of T24-ras mRNA was evaluated on either the cytological level or the molecular level. The malignant cells expressing ribozyme were partially reversed in morphology as evidenced by slower growth speed, partial recovery of contact-inhibition, reduced frequency of colony forming in soft agar and close-to-normal behaviour in agglutination teat. The primer extension experiment verified that the ribozyme had efficiently cleaved the transcripts of T24-ras gene at the target site in vivo.

3T3 Cells↗
PubMed1996

[Treatment of cerebrospinal rhinorrhea under nasal endoscope with EC ear-head adhesive].

Five cases of cerebrospinal rhinorrhea in frontal, ethmoid or sphenoidal sinus were repaired under endoscope with ear-head adhesive with satisfactory results. The advantages of the method are as follows: (1) The sufferings of the patient are minor and intercranial complications are fewer: (2) The location and size of the fistula are clear under endoscope: (3) The success rate is higher due to the application of ear-head adhesive: (4) With the use of muscles and fasciae outside the nose, the bleeding in nasal cavity may be avoided: (5) The curettages of the mucosa around the fistula and dura mater is helpful to the adherence of ear-head adhesive with these tissues.

Adhesiveness↗
PubMed1996

[Screening for mutations in the PAH gene in Chinese: a new splice and a novel polymorphic mutation].

OBJECTIVE: to screening for novel mutations in the phenylalanine hydroxylase (PAH) genes in Chines as to investigate the molecular basis of phenylketonuria and to raise its diagnosis rate. METHODS: We applied the polymorase chain reaction (PCR) on amplified DNA fragment harboring exon 4 of the PAH gene. For novel mutations detected, the amplified fragments were sequenced by using ds-DNA cycle-sequencing method. RESULTS: Seven out of 24 cases of PKU had different kinds of band-shifting, which are subjected to two patterns of polymorphism. The first one, only in one case, has one mutation band migrating before the normal bands, while, the second one, which was common among the cases, had both the mutation bands running ahead of the normal bands. By sequence analysis, these polymorphic patterns corresponded to two noval mutations. One was a GT-->AT substitution at the 5' splice donor site of intron 4, and the other is an A to C transversion at position-11 of intron 3. CONCLUSION: The two mutations are both first reported. The 5' donor splicing mutation may result in skipping of the preceeding exon during RNA processing. The A to C transversion, which accounted for about 20% of the Chinese PKU alleles is a polymorphism changes.

DNA Mutational Analysis↗
PubMed1996

[Studies on peptide. XIX: Hepatitis C virus (HCV) immune selection].

HCV has characteristics of rapid variability. The amino terminus of E2/NS1 of HCV (amino acids sequence 384-414), which is hypervariable with respect to both nucleotide and amino acid sequence, has been termed the E2 HV domain or HVR1. The E2 HV domain appears to be a rapidly evolving region of the HCV genomes which may contain linear neutralizing epitopes and the E2 HV are under immune selection. For further studies of the immunogenicity on E2 HV of HCV, we selected three peptide fragments from the full length of E2 HV region sequence and synthesized them with SPPS method. The amino acid sequences are shown as following: P2: VDGDTHVTGGAQAKTTNR (381-398); P9: STHVTGAVQGHSIRGTTSLFTSGPAQKIQ (384-412); P10: RTYTSGGTAGHTTSGITSLFSPGASQKIQ (384-412). From the results of ELISA and anti-peptide Abs of rabbit sera, we conclude that there are anti-E2 HV Abs in immune host but they could not neutralize HCV, so these Abs were not reactive with all E2 HV epitopes that resulted in immune selection of escape mutants; the anti-E2 HV Abs, probably from the same genotype, contained some common structure in which E2 HV epitopes react with other anti-E2 HV Abs at 30%: the C-terminus of E2 HV region (398-412) caused the immune response to rabbits.

Amino Acid Sequence↗