Biomedical subjects

M Liu

Publications and source records attributed to M Liu.

At least 253 records · Page 14Linked to original sources

PubMed2000

[Research progress of fibroblast and wound repair].

OBJECTIVE: To review the recent advances in fibroblast study and its role in wound repair. METHODS: Recent original articles related to wound repair were retrieved extensively, and the effect of fibroblast on every stages of repair were summed up and comprehended. RESULTS: Fibroblast plays important roles in granulation formation, wound contraction, matrix synthesis, wound repair, scar formation and scarless repair by means of growth factors modulation. CONCLUSION: The understanding of fibroblast in the wound repair can promote the progress of biological therapy of wound repair and scar prevention.

Animals↗

PubMed2000

[Local chemotherapy by fibrobronchoscopy for advanced bronchogenic carcinoma].

OBJECTIVE: To observe the effectiveness of treatment in the patients with advanced bronchogenic carcinoma of local chemotherapy with fibrobronchoscopy, combined with systematic chemotherapy. METHODS: 40 patients with advanced bronchogenic carcinoma were divided into the tested group (20 patients) and the control group (20 patients) randomly. By fibrobronchoscopy with its matched injecting needle, carboplatin 300 mg were injected into the centre of the tumor and the surroundings, combined with the routine carboplatin and etoposide (CE) regimen. While the control group was treated only by intravenous chemotherapy with the routine CE regimen. RESULTS: In the 20 patients with local chemotherapy by fibrobronchoscopy combined with intravenous chemotherapy, 7 cases (35%) were completely cured and 11 cases (55%) showed partial recovery, other 2 cases without change. The 90% effective rate was significantly higher than 55% of the control group (P < 0.05). CONCLUSIONS: The local chemotherapy by fibrobronchoscopy can remarkably reduce the size of tumor, and relieve symptom of dyspnea. Intravenous chemotherapy alleviated the obstruction caused by tracheal or bronchial neoplasms. The combined therapies led to much better therapeutic effect and symptomatic relief than those by the routine CE regimen.

Aged↗

PubMed2000

[Distribution of HIV resistance CCR5-delta 32, CCR2-64 I and SDF1-3'A alleles and their polymorphisms in the Han population in China].

OBJECTIVE: To study the frequency and polymorphism of three mutations (CCR5(Delta)32, CCR2-64I and SDF1-3'A alleles) conferring resistance to determined HIV-1/AIDS in the indigenous Han population in China. METHODS: The study population included 1,267 subjects, of which consisted 98.7% (1,251/1,267) Han people. The genotypes of the three mutations were respectively, detected by polymerase chain reaction (PCR) for CCR5(Delta)32 mutation, or by PCR/RFLP (restriction fragment length polymorphism) assay with the digestion of restriction endonuclease Bsa BI and Msp I for CCR2-64I and SDF1-3'A mutations. DNA sequencing was employed to confirm the accuracy of PCR or PCR/RFLP products. RESULTS: The frequency of the mutant alleles were: 0.00119 for CCR5(Delta)32; 0.20023 for CCR2-64I, and 0.28723 for SDF1-3'A. The three heterozygous CCR5-wt/Delta32 mutants were identified and no homozygotes were detected in indigenous Han population. The frequencies of CCR2-64I and SDF1-3'A alleles in China were higher than those of Caucasians descents in the USA and Europe. CONCLUSION: Our data was the first findings on the frequency and polymorphism of CCR5(Delta)32, CCR2-64I and SDF1-3'A alleles in indigenous Han population in China which implied that the indigenous Han people might have a higher genetic susceptibility to the infection of sexually transmitted HIV-1 (R-5) strain. Further study is needed to clarify the significance of higher frequency of CCR2-64I and SDF1-3'A alleles in Han population.

Alleles↗

PubMed2000

[Polymorphisms of chemokine receptor alleles influencing genetic susceptibility to HIV-1 infection in Mongolia population in China].

OBJECTIVE: Mutant frequency and polymorphism of HIV-1 resistance CCR5-Delta32, CCR2b-64I and SDF1-3'A alleles were investigated in Chinese population from Mongolian ethnic origin. METHODS: Whole blood samples from 134 Mongolian subjects were collected randomly and their genomic DNA were extracted using Qiagen Blood Kit. Allelic frequency was identified by means of PCR or PCR-RFLP analysis. Allelic polymorphism in population and between sex in the sample as well as correlation of the three genes were analyzed by chi(2) test. RESULTS: The frequencies of the three alleles were as following: CCR5-Delta32 1.1%, CCR2b-64I 24.8% and SDF1-3'A 22.0% respectively. Distribution of the three mutant alleles among the Mongolian population was in accordance with Hardy-Weinberg equilibrium. Statistical analysis showed there was a higher frequency of CCR2b-64I in female than in male subjects (29.2% vs 19.7%). No Statistical difference was found in the allelic frequencies of both CCR5-Delta32 and SDF1-3'A between male and female individuals. CONCLUSION: Compared with the Caucasian American, there were higher frequencies of CCR2b-64I and SDF1-3'A alleles and lower frequency of CCR5-Delta32 allele found in Mongolian population while the factors responsible for the variation of genetic polymorphisms in different ethnic populations need to be clarified.

Adolescent↗

PubMed2000

[Relationship between folate, vitamin B12, total plasma homocysteine and mutation of reductase].

OBJECTIVE: To study relationship between serum and red blood cell (RBC) folate, serum vitamin B(12) (VB(12)), total plasma homocysteine (tHcy), thermolabile genotypes, and activity of methylene-tetrahydrofolate reductase (MTHFR). METHODS: Thirty-four non-pregnant and healthy mothers who gave birth to babies with neural tube defects (NTDs) and 42 mothers to normal babies previously were chosen. Plasma tHcy, RBC and serum folate, serum VB(12), activity of MTHFR and thermolabile genotypes were determined for all of them. RESULTS: There was no significant difference in plasma tHcy, RBC and serun folate between case and control groups. Serum VB(12) was significantly lower in mothers of babies with NTDs than in those with normal ones. Plasma tHcy correlated with RBC folate inversely (P < 0.05). Mean plasma tHcy for thermolabile homozygous mutation of MTHFR was significantly higher than that for either heterozygous mutation or wild homozygous mutation (P < 0.001). There was no significant difference in serum folate between groups with varied MTHFR genotypes. Plasma tHcy was slightly greater in those with lower serum folate than in those with higher one, and correlated inversely with activity of MTHFR. CONCLUSIONS: Increase in plasma tHcy correlates with homozygous mutation of thermolabile MTHFR and decrease in activity of MTHFR. Higher level of folate in the body can interfere the relationship between plasma tHcy and activity of MTHFR.

Adult↗

PubMed2000

[Application of less-than-one-hour in situ hybridization to diagnosis of infectious agents].

Less-than-one-hour in situ hybridization manual method for immunocytochemical analyses of formalin-fixed, paraffin embedded tissue sections was used to detect infectious agents. The method employs capillary action to sequentially apply, incubate and remove liquid reagents from opposite pairs of glass microscope slides and allows for simultaneous immunocytochemical analyses. We used this method to detect EB virus in nasopharyngeal tissues and human papilloma virus in cervical tissues. This rapid and sensitive procedure represents a significant improvement for clinical immunocytochemical and research laboratories alike.

Epstein-Barr Virus Infections↗

PubMed2000

[Distribution of Prevotella intermedia in the periodontal plaques of children and their parents].

OBJECTIVE: To investigate the distribution of Prevotella intermedia (Pi) among family members by culturing technique and biochemical identification. METHODS: Of all 60 families, 181 subjects were included in the study. Supragingival and subgingival plaques were collected and cultured, 279 strains of black-pigmented gram-negative anaerobes were obtained. Biochemical identifications were performed. RESULTS: Pi could be identified from parents and children with healthy periodontal status. The prevalence of Pi in children was 70.49%, which was significantly higher than that in adults (43.33%). CONCLUSION: The result indicates that Pi might be an opportunistic periodontal pathogen that could be colonized in periodontal plaques easily and early. To study the exact role of Pi in the pathogenesis of periodontitis, it is necessary to do longitudinal following study of the subjects.

Adolescent↗

PubMed2000

[Expression of c-fos mRNA following moderate lateral fluid percussion brain injury in rats].

This experiment was designed to study the expression of c-fos mRNA in brain following moderate lateral fluid percussion brain injury in rats and to observe the temporal pattern of its expressions following percussion. Male Sprague-Dawley rats were divided into normal control, sham operation control and injury groups. The rats of the injury group were subjected to moderate lateral fluid percussion injury (0.2 MPa). The injury group was then subdivided into 5 min, 15 min, 30 min, 1 h, 2 h groups according to the time elapsed after injury. The expression of c-fos mRNA was studied with reverse transcription polymerase chain reaction(RT-PCR) semi-quantitatively. c-fos mRNA in cortex and brain stem was expressed weakly in control groups. After 5 min of percussion, the expression of c-fos mRNA increased progressively and remained elevated up to 2 h after brain injury. This result suggested that the induction and expression of the c-fos mRNA in cortex and brain stem after fluid percussion brain injury were increased rapidly. The temporal pattern of induction in cortex was similar to that in brain stem.

Animals↗

PubMed2000

[Study on the improvement of plasmid stability in soybean rhizobia].

By using luxAB as the report genes, 3.2 kb parCBA/DE gene fragment from pTR102 was inserted into pLAFR3 which contained a 3.7 kb enhancing fragment and deleted its cos site. Recombinant plasmids pHN155 and pHN156 were obtained. Contrasted plasmids pHN157 and pHN158 which contained cos site were also constructed. These four plasmids were transferred into Sinorhizobium fredii HN01 by tri-parental mating, and plasmid pHN155 and pHN158 were introduced into Bradyrhizobium japonicum TA11 by two-parental mating. The stability of the above plasmids was compared under free-living conditions and the results showed that the parCBA/DE could obviously enhance plasmid stability both in S. fredii and B. japonicum, and deletion of cos site showed only less effect.

Bradyrhizobium↗

PubMed2000

[Study of xixin, duzhong and mixture to the antioxidant system of D-galactose-induced senile mice].

D-galactose induced mice aging model were used in this experiment. This study investigated the effect of the herb on the activity of superoxide dismutase(SOD), glutahione peroxidase (GSH-Px) and NOS, in order to know the damages degree of body by free radical and determine the changes of above index after giving Duzhong, Xixin and their Mixture 15, 30 and 45 days, at the same time, the mechanism of their effect on antiaging was probed. The results were as follows: The activity of SOD, GSH-Px and NOS was increasing before middel age and decreasing after middelage(P < 0.01); Xixin and Duzhong could enhance the activity of SOD, GSH-Px and NOS; The time of effect for mixture and Duzhong to above index was short than Xixin's. The time of Mixture and Duzhong was 15 days, and Xixin was 30 days.

Aging↗

PubMed2000

[Papanicolaou test in pregnancy].

OBJECTIVE: To investigate the necessity, safety and acceptability of routine Papanicolaou (Pap) smear in pregnant women and cytological characteristics of the smears during pregnancy. METHODS: Pap smear were performed in 954 pregnant women, 1,053 normal controls and 1,908 gynecological out-patients. The cytological preparations were analyzed by using PAPNET method and following Bethesda (TBS-NCI) diagnostic criteria. Quality control was carried out by following TBS-NCI standard. RESULTS: Abnormal epithelial change was found in 89 women (89/954, 9.3%) of pregnant group, which was quite similar to normal controls group and gynecological group. Occurrence rate of cervical squamous intraepithelial lesion (SIL) was the lowest in pregnant group (0.94%, 9 in 954 cases), comparing with control group (2.75%) and gynecological group (6.23%). However, pregnant group had the highest infection rate (89.9%), as compared to gynecological group (64.5%), and normal controls group (69.1%) (P < 0.01). CONCLUSIONS: Cervical Pap smear test is necessary, safety and acceptable for routine prenatal tests. Any pregnant women with infections must be treated as nonpregnant one.

Adult↗

PubMed1999

High affinity IgG receptor activation of Src family kinases is required for modulation of the Shc-Grb2-Sos complex and the downstream activation of the nicotinamide adenine dinucleotide phosphate (reduced) oxidase.

We used the U937 cell line to examine the modulation of adaptor protein interactions (Shc, Grb2, and Cbl) after high affinity IgG receptor (FcgammaRI) cross-linking, leading to the formation of the Grb2-Sos complex, the activation of Ras, and the regulation of the respiratory burst. Cross-linking of FcgammaRI induced the conversion of GDP-Ras to GTP-Ras reaching a maximum 5 min after stimulation. Concomitant with Ras activation, Sos underwent an electrophoretic mobility shift and the Sos-Grb2 association was increased (6-fold). The Grb2-Sos complex was present only in the membrane fraction and was augmented after FcgammaRI stimulation. Tyrosine-phosphorylated Shc, mainly the p52 isoform, was observed to transiently onload to the membrane Grb2-Sos complex on FcgammaRI stimulation. Cross-linking of FcgammaRI induces the tyrosine phosphorylation of Cbl, which forms a complex with Grb2 and Shc via the Cbl C terminus. Kinetic experiments confirm that Cbl-Grb2 is relatively stable, whereas Grb2-Sos, Grb2-Shc, and Cbl-Shc interactions are highly inducible. The Src family tyrosine kinase inhibitor, PP1, was shown to completely inhibit Shc tyrosine phosphorylation, the Shc-Grb2 interaction, and the FcgammaR-induced respiratory burst. Our results provide the first evidence that the upstream activation of Src kinases is required for the modulation of the Shc-Grb2 interaction and the myeloid NADPH oxidase response.

Adaptor Proteins, Signal Transducing↗

PubMed1999

Identification and characterization of glucoresponsive neurons in the enteric nervous system.

We tested the hypothesis that a subset of enteric neurons is glucoresponsive and expresses ATP-sensitive K(+) (K(ATP)) channels. The immunoreactivities of the inwardly rectifying K(+) channel 6.2 (Kir6.2) and the sulfonylurea receptor (SUR), now renamed SUR1, subunits of pancreatic beta-cell K(ATP) channels, were detected on cholinergic neurons in the guinea pig ileum, many of which were identified as sensory by their costorage of substance P and/or calbindin. Glucoresponsive neurons were distinguished in the myenteric plexus because of the hyperpolarization and decrease in membrane input resistance that were observed in response to removal of extracellular glucose. The effects of no-glucose were reversed on the reintroduction of glucose or by the K(ATP) channel inhibitor tolbutamide. No reversal of the hyperpolarization was observed when D- mannoheptulose, a hexokinase inhibitor, was present on the reintroduction of glucose. Application of the K(ATP) channel opener diazoxide or the ob gene product leptin mimicked the effect of glucose removal in a reversible manner; moreover, hyperpolarizations evoked by either agent were inhibited by tolbutamide. Glucoresponsive neurons displayed leptin receptor immunoreactivity, which was widespread in both enteric plexuses. Superfusion of diazoxide inhibited fast synaptic activity in myenteric neurons, via activation of presynaptic K(ATP) channels. Diazoxide also produced a decrease in colonic motility. These experiments demonstrate for the first time the presence of glucoresponsive neurons in the gut. We propose that the glucose-induced excitation of these neurons be mediated by inhibition of K(ATP) channels. The results support the idea that enteric K(ATP) channels play a role in glucose-evoked reflexes.

Adenosine Triphosphate↗

PubMed1999

Combination therapy with the farnesyl protein transferase inhibitor SCH66336 and SCH58500 (p53 adenovirus) in preclinical cancer models.

SCH66336 is a p.o.-active, farnesyl protein transferase inhibitor. SCH66336 inhibits farnesylation of RAS and other proteins in tumor cells and suppresses tumor growth in human xenograft and transgenic mouse cancer models in vivo. SCH58500 is a replication-deficient, recombinant adenovirus, which expresses the human p53 tumor suppressor. In preclinical models, SCH58500 has therapeutic efficacy against a wide range of human tumor types containing nonfunctional p53 and enhanced activity in combination with many chemotherapeutic drugs. Here we report that combination therapy with SCH66336 and SCH58500 has synergistic or additive antiproliferative effects on a panel of tumor cells lines in vitro. The efficacy of the three-drug combination of SCH66336, SCH58500, and paclitaxel was also examined in vitro. Each two-drug interaction displayed such marked synergy, the addition of a third drug to the statistical model could only yield additivity. Greater combined efficacy for SCH66336 and SCH58500 was also observed in vivo in the DU-145 human prostate and wap-ras/F transgenic mouse cancer models.

Adenocarcinoma↗

PubMed1999

Hydrogen storage in single-walled carbon nanotubes at room temperature

Masses of single-walled carbon nanotubes (SWNTs) with a large mean diameter of about 1.85 nanometers, synthesized by a semicontinuous hydrogen arc discharge method, were employed for hydrogen adsorption experiments in their as-prepared and pretreated states. A hydrogen storage capacity of 4.2 weight percent, or a hydrogen to carbon atom ratio of 0.52, was achieved reproducibly at room temperature under a modestly high pressure (about 10 megapascal) for a SWNT sample of about 500 milligram weight that was soaked in hydrochloric acid and then heat-treated in vacuum. Moreover, 78.3 percent of the adsorbed hydrogen (3.3 weight percent) could be released under ambient pressure at room temperature, while the release of the residual stored hydrogen (0.9 weight percent) required some heating of the sample. Because the SWNTs can be easily produced and show reproducible and modestly high hydrogen uptake at room temperature, they show promise as an effective hydrogen storage material.

Journal Article↗

PubMed1999

Interdomain interactions regulate GDP release from heterotrimeric G proteins.

The role of interdomain contact sites in basal GDP release from heterotrimeric G proteins is unknown. G(alpha)(o) and G(alpha)(i1) display a 5-fold difference in the rate of GDP dissociation with half-times of 2.3 +/- 0.2 and 10.4 +/- 1.3 min, respectively. To identify molecular determinants of the GDP release rate, we evaluated the rate of binding of the fluorescent guanine nucleotide 2'(3')-O-(N-methyl-3'-anthraniloyl)guanosine 5'-O-(3-thiotriphosphate) (mGTPgammaS) to chimers of G(alpha)(o) and G(alpha)(i1). Although no one region of the G protein determined the GDP dissociation rate, when the C-terminal 123 amino acids in G(alpha)(i1) were replaced with those of G(alpha)(o), the GDP release rate increased 3.3-fold compared to that of wild-type G(alpha)(i1). Within the C-terminal portion, modification of four amino acids in a coil between beta4 and the alpha3 helix resulted in GDP release kinetics identical to those of wild-type G(alpha)(o). Based on the G(alpha)(i1)-GDP crystal structure of this region, Leu(232) appeared to form a hydrophobic contact with Arg(144) of the helical domain. The role of this interaction was confirmed by G(alpha)(i1) L232Q and G(alpha)(i1) R144A which displayed 2-5-fold faster GDP release rates compared to wild-type G(alpha)(i1) (t(1/2) 4.7 and 1.5 min, respectively), suggesting that interdomain bridging contacts partially determine the basal rate of GDP release from heterotrimeric G proteins.

Amino Acid Sequence↗

PubMed1999

Gadolinium induces domain and pore formation of human erythrocyte membrane: an atomic force microscopic study.

Lanthanide cations bind to human erythrocyte membranes and enhance cell permeability. It was postulated that this effect is due to their likeness with calcium ions, which have been used to induce perforation of cells. However, the nature and mechanism of the perforation are still not clear. In the present work, the change in surface topography of erythrocyte membranes exposed to various gadolinium species was imaged with an atomic force microscope (AFM) in order to get direct evidence of perforation. The images of the whole cell and regions in nanometer scale showed that the normal surface is featured by closely packed nanometer size particles. The AFM images showed that Gd(3+) binding to erythrocytes led to domain structure at low concentration and pore formation at higher concentration. The domain structures that appeared after incubation with 1.0x10(-6)-1.0x10(-5) mol/l Gd(3+) solution for 30 min are featured by the particles aggregated to form ranges and the separations among them enlarged to gorges. With a higher concentration, 2.5x10(-5) mol/l Gd(3+), the further aggregation developed into crater-shaped 'pores'. By washing with EDTA the 'pores' can be resealed but the domain structure remained. The anionic complex of Gd(3+), [Gd(Cit)(2)](3-) of this concentration, can only induce the domain structure formation. The domain and 'pore' structures mediated by Gd(3+) concentrations might be responsible for both enhanced permeability and perforation. The mechanism of Gd-induced domain formation and perforation is discussed on the basis of aggregation of membrane proteins and the coexistence of different phases of membrane lipids resulting from Gd(3+) binding.

Animals↗

PubMed1999

Ultra-short columns for low-pressure ion chromatography.

Since the development of low-pressure ion chromatography (LPIC), many inorganic cations and anions as well as organic acids could be analyzed at a low-pressure of 1.96 x 10(5)-2.94 x 10(5) Pa. And the ultra-short columns took the place of the common long chromatographic columns. Furthermore, the ultra-short columns of LPIC not only reduced the system pressure appreciably, but also achieved high sensitivity and precision. In order to assess the characteristics of the super-short columns, much analysis, i.e., the analysis of alkali metals, alkaline earth metals, transition-metals, rare-earth elements, inorganic anions and organic acids as well as the common amino acids, were conducted. Moreover, excellent results were obtained from the LPIC columns.

Chromatography, Liquid↗