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Biomedical subjects

F Liu

Publications and source records attributed to F Liu.

At least 469 records · Page 26Linked to original sources
PubMed1997

[Immunogenecity of expressed protein p68 from recombinant plasmid rpDJt in L. interrogans serovar lai].

There are two types of infection caused by pathogenic microorganisms, intracellular infection and intercellular infection. Infection of pathogenic leptospira is an intercellular infection. The immunological reaction of host to intercellular infection is unique. The potential immunogen of an expressed protein should meet three criteria: it can be degraded (by antigen-present cells in the host); it should have antigenic epitope which can be recognized by specific antibodies and have at least one epitope that can be recognized by an MHC II protein and T cell receptor. In this study we report the cloning of an L. interrogans protein in plasmid rpDJt and the immunogencity of the expressed protein derivative. A genomic library of L. interrogans serovar lai strain 017 was constructed with the plasmid vector pUC18. Recombinant plasmids, designated pDJH2 and pDJ8 were screened from the bank. EcoRI-inserted fragment of 1. 9 kb recombinant DNA of pDJH2 was ligated into T7 RNA polymerase/promoter vectors (pT7-7). Then they were transformed into E. coli JM109 (De3), one of subclones, designated rpDJt was achieved. SDS-PAGE showed that the molecular weights of expression proteins were 68 kd and 23 kd respectively, designated p68 and p23. Purifying and isolating p68 and p23, we separated them from SDS-Polyacrylamide gels by using Side-Strip method. After fragmenting and electroeluting, p68 and p23 were injected into guinea pigs and rabbits. An extremely strong immune response to p68 was obtained since an anti-p68 antibody response could be detected to a dilution 1:524,288 (guinea pigs) and 1:262,144 (rabbits) by ELISA while anti-P23 antibody being 1:1024 (the same to guinea pigs and rabbits). The results of improved MTT and conA 3HTdR transformation methods showed the activities and proliferation of Th-cells were increased in guinea pigs after p68 immunization (IL-6, 83.25 IU/ml, IL-2, 28.75 IU/ml; RPI, 2.04, SI, 65.62%) Thlymphocyte existed in two subclasses, the Th1- and Th2-cells. A major role of Th2-cells is to "help" B-cells differentiate, replicate, and secrete antibody. The properties of these interactions explain why p68 makes good antigen and p23 does not. The antigens responsible for eliciting the production of protective antibodies are not known; however, several outer membrane proteins on L. interrogans are candidates for vaccine. Our results suggest that expresion protein p68 from recombinants (rpDJt) may be a candidate for gene engineered subunit vaccine for Leptospirosis.

Animals↗
PubMed1997

[Construction of genomic library of L. interrogans serovar lai using lambda gt11 as the vector and a study of recombiant plasmid pDL121].

A genomic library of L. interrogans serovar lai strain 017 has been constructed using lambda gt11 as the vector. DNA was partially digested by two blunt-end restriction enzymes, then methylated with EcoR I methylase; after EcoR I linker was added to the DNA, the linker-ended DNA was ligated to the dephosphorylated EcoR I digested lambda gt11 arms. The recombined DNA was packaged in vitro, and used to transduct E. coli Y1090 for amplification. There were 2.1 x 10(6) recombinant bacteriophages as recognized by their ability to form white plaques plated on Lac host in the presence of both IPTG and X-Ga1. A positive clone, designated lambda DL12, was screened with a rabbit anti-serum against L. interrogans serovar lai from the genomic library. The DNA from lambda DL12 was subcloned into plasmid pUC18. A recombinant (designated as pDL121) was obtained. SDS-PAGE analysis indicated that a 23 kd was expressed in E. coli JM 103 harboring pDL121. Western blotting analysis showed that a specific protein band molecular weight of 23 kd could be recognized by the rabbit antiserum against L. interrogans serovar lai strain 017.

Cloning, Molecular↗
PubMed1997

[Detection of Epstein-Barr virus in lymphoproliferative diseases by in situ hybridization].

OBJECTIVE: To study the relationship between Epstein-Barr virus and various lymphoproliferative diseases in China. METHODS: Tissues from 214 patients with lymphoproliferative diseases were examined for the presence of Epstein-Barr virus (EBV) using in situ hybridization with EBV's LMP gene as probe. RESULTS: The positive rate of EBV in Hodgkin's disease(HD), Non-Hodgkin's Lymphoma(NHL), benign lymphoid proliferative disease(BLP) was 30.0%(15/50), 14.0%(18/129), 2.9%(1/35), respectively. Among NHL, EBV was detected in 28.1%(9/32) of high grade lymphoma (HNHL), 10.5%(9/84) of medium grade lymphoma(MNHL) and in none(0/9) of low grade lymphoma(LNHL). Significantly higher rates than that of BLP were observed in HD and HNHL. No significant differences in rates among patients with MNHL, LNHL and BLP. CONCLUSION: EBV may be involved in the pathogenesis of HD and HNHL, but not in MNHL and LNHL.

Adult↗
PubMed1997

[The scavenging system designed for inhaled nitric oxide].

Inhaled nitric oxide must take care of the potential adverse effect of nitric oxide and higher oxides of nitrogen (nitric dioxide and others. So we designed this three stages scavenging system to satisfy the demand of inhaled nitric oxide and prevent environmental contamination.

Equipment Design↗
PubMed1997

[Chemical constituents of Isodon pharicus (Prain) Murata].

Two compounds were isolated from Isodon pharicus. Their structures were elucidated as 11 beta, 13 alpha, 15 alpha-trihydroxy-entkaur-16-en-3 alpha-(beta-D-glucoside) (named isodopharicin F) and eugenyl-beta-D-glucopyranoside by spectral data and chemical evidence.

Drugs, Chinese Herbal↗
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

[Effects of cytokines on multidrug-resistance in K562/A02 cells].

OBJECTIVE: To explore the effects of cytokines on human leukemic cell line K562/S and its multidrug-resistant counterpart K562/A02. METHODS: The toxicities of cytokines and the IC50 (the concentration causing 50% inhibition of cell growth) of DNR were assayed by MTT method; intracellular drug concentration was measured by fluorometry; p-glycoprotein (p-gp) expression was detected by APAAP and mdr-1 mRNA was assayed by RT-PCR. RESULTS: The IC50 of DNR for K562/A02 and K562/S cells were 45.08 microg/ml and 0.607 microg/ml, respectively. Pretreating K562/A02 cells with rhu IFN (500 U/ml) or rhu IL-2 (250 U/ml) for 24 hours partially restored the sensitivity of K562/A02 cells to DNR (IC50 were 16.39 and 11.96 microg/ml, respectively) but had not effect on K562/S cells, and it elevated the intracellular DNR accumulation in K562/A02 from 2151 ng/mg x protein to 2570 and 2503ng/mg x protein, respectively. p-gp and mdr-1 mRNA were not down regulated. By contrast, rhu G-CSF and rhu GM-CSF had no effect on either K562/A02 or K562/S. CONCLUSION: rhu IFN or rhu IL-2 could partially restore the sensitivity of K562/A02 to DNR and elevate the intracellular DNR accumulation via a mechanism independent of p-gp or mdr-1 mRNA down-regulation.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1997

[Plasma glutamine level monitored with high performance liquid chromatography for patient infusing glutamine after small bowel transplantation].

To promote the restoration of the structure and functions of the graft intestine for a patient with small bowel transplantation, the authors gave intravenous infusion of 5% glutamine to the patient and the blood glutamine levels were determined with HPLC technique. The ultrafiltration technique was adapted to remove blood proteins. Good separation could be achieved when using micro-Bondapak C18 as separation cartridge, phthaldialdehyde as derivatization agent, gradient elution with methanol and phosphate buffer and detection at wavelength of 340 nm. The recovery rate was 90% to 105% and the lower limit of detection was 40 micromol/L with satisfactory separation. The results of this method are proved to be a timely and reliable indicator for glutamine level in blood for patients of small bowel transplantation with glutamine infusion.

Chromatography, High Pressure Liquid↗
PubMed1997

The protein cofactor allows the sequence of an RNase P ribozyme to diversify by maintaining the catalytically active structure of the enzyme.

To study the effect proteins have on the catalysis and evolution of RNA enzymes, we simulated evolution of RNase P catalytic M1 RNA in vitro, in the presence and absence of its C5 protein cofactor. In the presence of C5, functional M1 sequence variants (not catalytically active in the absence of C5) were selected in addition to those identical to M1. C5 maintains the catalytically active structure of the variants and allows for an enhanced spectrum of M1 molecules to function in the context of a ribonucleoprotein (RNP) complex. The generation of an RNP enzyme, requiring both RNA and protein components, from a catalytically active RNA molecule has implications for how modern RNP complexes evolved from ancestral RNAs.

Bacterial Proteins↗
PubMed1997

[Cloning of BRCA1 cDNA and detection of BRCA1 mRNA expression in breast cancer cells].

The fragment of BRCA1 cDNA obtained by reverse transcription and polymerase chain reaction(RT-PCR) was inserted into plasmid pUC118 and demonstrated by DNA sequencing. Nucleotide sequence analysis demonstrated that the cloned cDNA for BRCA1 includes zinc finger domain. Two differences in nucleotides were found as compared with the sequence published. One occurs at nucleotide number 409 where Creplaced by A (Asp-->Glu). Another difference occurs at nucleotide number 879 where A replaced by T (samesense mutation). In order to further study the relationship-between BRCA1 function and breast cancer, the probe was prepared from the recombinant plasmid and then hybridized to total RNAs from 6 cases of breast cancer. Compared with normal cells, the expression level of BRCA1 mRNA was normal in 4, decreased markedly in 1, and in one patient there was no any expression of BRCA1 mRNA at all. The results suggested that the expression of BRCA1 mRNA was relatively low in some breast cancer cells.

Amino Acid Sequence↗
PubMed1997

[Preliminary studies of auditory fusion frequency in noise effects].

Auditory fusion frequency (AFF) of impulse sound and paired pitch in 80 workers exposed to noise and 60 non-exposed ones were measured to study the relationship between AFF and auditory fatigue. AFF test software was made by the authors themselves, and a stimulating sound signal was evoked in a personal computer. Relationship between AFF in non-exposed workers and their ages was explored, and AFF in exposed ones before and after their exposure was compared. Results showed that no relationship between AFF and their sex and ears in non-exposed group was found. There was a significant difference in AFF between groups of 50-59-year and less than or equal to 49-year. Stimulating sound was more sensitive in its carrier wave or center frequency of 1,000 Hz, and paired pitch has higher value in screening for subjects with auditory threshold shift at about 1/40 octave band. There was significant consistency in transient auditory threshold shift, an important indicator of AFF and auditory fatigue. Measurement of AFF is more stable, repeatable and less deviated, and needs only simple acoustic conditions. Hence, it is a practical superthreshold audiometry.

Adult↗
PubMed1997

[The peripheral blood levels of TNF alpha and PLA2 activities in dialysis and non-dialysis patients with uremia].

The levels of tumor necrosis factor a (TNF alpha) and phospholipase A2 (PLA2) in peripheral blood were determined by means of the ELISA and improved micromethod in 31 patients with urmia and 12 normal healthy persons. The results showed: 1. In non-dialysis group and during a single dialysis session, a significant increase in the levels of TNF alpha was observed. 2. In non-dialysis and peritoneal dialysis patients, serum levels of PLA2 were significantly increased compared to normal subjects. The results suggest that acute complications induced by hemodialysis are related to increasing levels of TNF alpha, souble PLA2 in cleared by hemodialysis.

Adult↗
PubMed1997

[Effects of danshen on solute transport by peritoneal dialysis].

Danshen injection was added in peritoneal dialysate with concentration of 6/1000. The D/P value of BUN, Cr and total protein and the D/Do value of glucose and the drained volume were observed. The results showed that the D/P value of BUN and Cr increased from the 2nd day of Danshen addition; the D/Do value of glucose increased from the 1st day of Danshen addition and then came to the original value from the 2nd day of Danshen addition; the D/P value of protein increased continuously from the 1st day of Danshen addition; the drained volume had no change.

Adult↗
PubMed1996

Direct binding of the proline-rich region of protein tyrosine phosphatase 1B to the Src homology 3 domain of p130(Cas).

Protein tyrosine phosphatase 1B (PTP1B) is an abundant intracellular enzyme that is thought to act as a negative regulator of certain signaling pathways. The C terminus of PTP1B contains two proline-rich regions which conform to the canonical class II Src homology 3 domain binding motif, Pro-X-X-Pro-X-Arg. In this study, we establish that PTP1B interacts with Crk, Grb2, and p130(Cas) in vitro and with at least one of these, p130(Cas), in intact cells. The interaction of PTP1B and p130(Cas) is independent of tyrosine phosphorylation but can be disrupted by replacing two critical proline residues in the proline-rich domain of PTP1B between amino acids 301 and 315. When wild-type PTP1B is expressed in 3Y1-v-crk cells, p130(Cas) shows substantial dephosphorylation, whereas the PTP1B proline mutant does not have this effect. In 3Y1 and 3Y1 v-crk-transformed fibroblasts, almost all of the total PTP1B and about 40% of total p130(Cas) co-sediment with membranes composed primarily of endoplasmic reticulum. These results suggest that the proline-rich domain between amino acids 301 and 315 in PTP1B binds Src homology 3-containing proteins and that p130(Cas) may be a physiological target of this phosphatase in cells.

Amino Acid Sequence↗
PubMed1996

Time-resolved optical diffusion tomographic image reconstruction in highly scattering turbid media.

The image of an object hidden in highly scattering media was reconstructed using a fast, noise-resistant algorithm newly applied to diffusion tomography. A pulsed light source producing scattered and transmitted light is examined at multiple times. Multiple source detector pairs around the medium are used to obtain data in many different directions. An inverse scattering algorithm with nonuniform regularization achieves rapid inversion convergence.

Journal Article↗
PubMed1996

Requirements for cleavage by a modified RNase P of a small model substrate.

M1 RNA, the catalytic RNA subunit of RNase P from Escherichia coli, has been covalently linked at its 3' terminus to oligonucleotides (guide sequences) that guide the enzyme to target RNAs through hybridization with the target sequences. These constructs (M1GS RNAs) have been used to determine some minimal features of model substrates. As few as 3 bp on the 3' side of the site of cleavage in a substrate complex and 1 nt on the 5' side are required for cleavage to occur. The cytosines in the 3' terminal CCA sequence of the model substrates are important for cleavage efficiency but not cleavage site selection. A purine (base-paired or not) at the 3' side of the cleavage site is important both for cleavage site selection and efficiency. M1GS RNAs provide both a simple system for characterization of the reaction governed by M1 RNA and a tool for gene therapy.

Base Sequence↗
PubMed1996

Interaction of transforming growth factor-beta receptor I with farnesyl-protein transferase-alpha in yeast and mammalian cells.

Transforming growth factor beta (TGF-beta) signals through two transmembrane serine/threonine kinases, known as TbetaR-I and TbetaR-II. Several lines of evidence suggest that TbetaR-II acts as a primary receptor, binding TGF-beta and phosphorylating TbetaR-I whose kinase activity then propagates the signal to unknown substrates. We report an interaction between TbetaR-I and the farnesyl-protein transferase-alpha subunit (FT-alpha) both in a yeast two-hybrid system and in mammalian cells. These findings raise the possibility that TGF-beta might regulate cellular functions by altering the ability of FT-alpha to catalyze isoprenylation of targets such as G proteins, lamins, or cytoskeletal components. However, we provide evidence that TGF-beta action does not alter the overall protein isoprenyl transferase activity in Mv1Lu mink lung epithelial cells. In fact, the beta subunits of farnesyl transferase and geranylgeranyl transferase, which are necessary for the activity of FT-alpha, prevent the association of FT-alpha with TbetaR-I. Furthermore, farnesyl transferase activity is shown to be dispensable for TGF-beta signaling of growth inhibitory and transcriptional responses in these cells. These results suggest that the interaction between TbetaR-I and FT-alpha does not affect the known functions of these two proteins.

Activin Receptors, Type I↗