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Biomedical subjects

Q Liang

Publications and source records attributed to Q Liang.

At least 55 records · Page 3Linked to original sources
PubMed1998

The relationship between caries activity and the status of dental caries--application of the Dentocult SM method.

OBJECTIVE: To study the relationship between caries activity and the status of dental caries in preschool children using a caries activity test (CAT). MATERIALS AND METHODS: The status of primary tooth caries in 229 children ages 3 to 5 was examined. Caries incidence, DFT, and caries severity index (CSI) were calculated. Based on the quantity of Streptococcus mutans in the oral cavity detected with Dentocult SM, a caries activity test, four grades of caries activity were classified: Grade 0 (< 10(4) colony-forming units/mL), Grade I (10(4)-10(5) CFU/mL), Grade II (10(5)-10(6) CFU/mL), and Grade III (> 10(6) CFU/mL). RESULTS: The results showed that 79.48% children had Grade I or higher caries severity. Significant differences of caries activity were found among different grades, which were highly correlated with caries incidence, DFT, and CSI (r = 0.22216, 0.31212, and 0.32276, respectively). CONCLUSIONS: As a CAT, Dentocult SM is a reliable method for measuring the status of dental caries in preschool children. It is also a valuable tool in the prevention and treatment of dental caries.

Child, Preschool↗
PubMed1998

[Effects of nao yi-an granule on hemorheological indexes and RCD (erythrocyte deformability) in patients with hemorrhagic stroke].

The effects of Nao Yi-an granule(Chinese medicine group, CMG) and western medicine (western medicine group, WMG) on hemorheological indexes and red cell deformability(RCD) were investigated in 40 patients with hemorrhagic stroke. The results showed that whole blood relative viscosity(high and low shear), whole blood reduced viscosity(high shear), plasma relative viscosity and RCD were significantly elevated before the treatment in both group than those of the control group(P < 0.01). After the treatment, the above indexes were lower in CMG than before the treatment and also lower in CMG than in WMG(P < 0.01). It is indicated that the Nao Yi-an granule is obviously superior to western medicine on the decrease of blood viscosity, increase of RCD, improvement of blood perfusion of brain tissue, protection of brain tissue and improved clinical in patients with hemorrhagic stroke.

Adult↗
PubMed1998

Signaling by HGF and KGF in corneal epithelial cells: Ras/MAP kinase and Jak-STAT pathways.

PURPOSE: To characterize the signaling pathways used by hepatocyte growth factor (HGF) and keratinocyte growth factor (KGF) in human corneal epithelial cells. METHODS: Cultures of SV40 large T antigen-transfected human corneal epithelial cells were treated with recombinant human HGF or KGF at 50 ng/ml to 100 ng/ml for 5 to 30 minutes and harvested for protein isolation. Immunoprecipitation was performed with antisera to signal transducers and activators of transcription 1 (STAT1), STAT3, Janus kinase 1 (Jak1), Shc, Grb2, Sos1, and HGF receptor (met). Immunoprecipitated proteins were analyzed by western blot analysis. Gel retardation experiments were carried out with first-passage human corneal epithelial cells to detect binding of STATs to the high affinity c-sis (platelet-derived growth factor) inducible DNA element (hSIE). Effects of HGF, KGF, and kinase inhibitors on mitogen-activated protein kinase (MAPK) activation were evaluated by western blot analysis and enzymatic assays. RESULTS: In human corneal epithelial cells, the phosphorylation of adapter protein Shc (52- and 66-kDa isoforms) was enhanced by HGF, but not by KGF. Phosphorylated HGF receptor coimmunoprecipitated with Shc, Grb2, and Sos1. Hepatocyte growth factor or KGF rapidly activated MAPK in corneal epithelial cells. The activation of MAPK (p42 and p44) by HGF or KGF was transient and decreased gradually within 1 hour. MAPK kinase 1 (MEK1) inhibitor PD098059 or the protein tyrosine kinase inhibitor genistein blocked MAPK activation. Activation of MAPK induced by HGF was partially inhibited by protein kinase C inhibitor calphostin C. Hepatocyte growth factor and KGF had no effect on the activation of Jak-STAT cascade components that are activated by epidermal growth factor. CONCLUSIONS: Hepatocyte growth factor and KGF activate Ras-MAPK pathways in human corneal epithelial cells. There may be at least two routes used by HGF in transmitting signals from its receptor to the MAPK cascade. One is the receptor-Grb2/Sos complex to the Ras pathway, and the other is through protein kinase C. Hepatocyte growth factor and KGF did not activate the Jak-STAT cascade components STAT1, STAT3, or Jak1 in corneal epithelial cells.

Blotting, Western↗
PubMed1997

Calicheamin-mediated DNA damage in a reconstituted nucleosome is not affected by histone acetylation: the role of drug structure in the target recognition process.

We have examined the role of drug structure and histone acetylation in DNA damage produced by the enediyne antibiotic calicheamicin gammaII in nucleosomes reconstituted onto the 5S rRNA gene of Xenopus borealis. Consistent with previous observations, calicheamicin damage at the 3'-end of a purine tract (positions -13 and -14) was enhanced in the nucleosome compared to the naked DNA while damage at other sites was somewhat reduced in the nucleosome. However, damage produced by esperamicin C, an analog of calicheamicin missing the terminal sugar-aromatic ring in the side chain, showed no enhancement at positions -13 and -14, and its sequence selectivity in naked DNA was markedly different from that of calicheamicin. This highlights the importance of the intact tetrasaccharide side chain in the recognition of the structural deformation occurring at the 3'-ends of purine tracts. Both drugs produced identical cleavage patterns in normal and hyperacetylated nucleosomes. Given the sensitivity of calicheamicin to local DNA conformation, this observation is consistent with other studies that suggest that histone acetylation alone does not significantly affect the local conformation of core DNA in the nucleosome.

Acetylation↗
PubMed1997

Tear hepatocyte growth factor (HGF) availability increases markedly after excimer laser surface ablation.

Tear cytokines and growth factors are likely to modulate the wound healing process following corneal epithelial injury. Hepatocyte growth factor (HGF) is a paracrine mediator of epithelial proliferation, motility, and differentiation that is produced by keratocytes and the lacrimal gland. Tear samples were collected preoperatively and one, two, and seven days postoperatively in eyes undergoing excimer laser surface ablation [photorefractive keratoplasty (PRK) or phototherapeutic keratoplasty (PTK)]. Tear HGF concentration was measured with a sensitive ELISA assay. Tear HGF production was calculated using the tear flow rate in the collection capillary and HGF concentration. Although the instantaneous concentration of HGF in tears decreased significantly in the days following PRK, a large increase in tear flow resulted in a marked increase in HGF bioavailability. The heparin-binding characteristics of HGF would result in increased binding to glycosaminoglycans and other heparin-like matrix components and, therefore, increased growth factor availability to the cognate recptor. This is the first report documenting changes in tear film HGF production. HGF may have an important function in maintenance and wound healing of the ocular surface epithelium since HGF is present in the normal tear film and the HGF secretion rate increases markedly in parallel with aqueous tear production following corneal surgical injury.

Enzyme-Linked Immunosorbent Assay↗
PubMed1997

Apoptosis in the cornea: further characterization of Fas/Fas ligand system.

This study was performed to further characterize expression and function of the Fas/Fas ligand system in the cornea. Specifically, these experiments examined (1) the effect of genetic inactivation of Fas or Fas ligand genes on keratocyte apoptosis in response to corneal epithelial wounding, (2) whether cultured human corneal epithelial and endothelial cells are competent to undergo apoptosis in response to Fas activation, (3) expression of membrane bound and soluble Fas and Fas ligand in corneal cells, and (4) the effect of IL-1 on expression of Fas and Fas ligand in corneal fibroblasts. Keratocyte apoptosis in response to corneal epithelial scrape detected by TUNEL assay and transmission electron microscopy was significantly decreased, but not eliminated, in Fas ligand -/- mice compared with control +/+ mice. There was also a decrease in Fas -/- mice that did not reach statistical significance. Thus, while the Fas/Fas ligand system is likely involved in regulating keratocyte apoptosis in response to epithelial wounding, systems with redundant function probably also modulate this response. Activation of the Fas receptor triggered death with ultrastructural changes characteristic of apoptosis in corneal epithelial and endothelial cells in culture. Since these cell types express both Fas and Fas ligand in vivo, systems must be in place to prevent uncontrolled activation via autocrine ligand-receptor interaction. Messenger RNAs coding for both membrane bound and soluble splicing variants of Fas were expressed in each corneal cell type, suggesting that soluble Fas production could be one mechanism to antagonize membrane bound Fas activation. Soluble Fas ligand protein was expressed in wounded ex vivo corneal epithelium, providing a mechanism for Fas ligand from epithelium to mediate keratocyte apoptosis. IL-1, however, also stimulated corneal fibroblasts to express Fas ligand mRNA and protein. Therefore, an alternative mode for epithelial injury to trigger keratocyte apoptosis may be by release of IL-1, subsequent induction of Fas ligand in keratocytes, and apoptosis mediated by autocrine mechanisms.

Animals↗
PubMed1997

A new automated computerized analyzing system simplifies readings and reduces the variability in ultrasound measurement of intima-media thickness.

BACKGROUND AND PURPOSE: A computerized analyzing system with manual tracing of echo interfaces for measurement of intima-media thickness and lumen diameter in carotid and femoral arteries was previously developed by our research group and has been used for many years in several laboratories. However, manual measurements are not only time consuming, but the results from these readings are also dependent on training and subjective judgement. A further problem is the observed drift in measurements over time. A new computerized technique for automatic detection of echo interfaces was therefore developed. The aim of this study was to evaluate the new automated computerized analyzing system. METHODS: The new system is based on dynamic programming and includes optional interactive modification by the human operator. Local measurements of vessel echo intensity, intensity gradient, and boundary continuity are extracted by image analysis techniques and included as weighed terms in a cost function. The dynamic programming procedure is used for determining the optimal location of the vessel interfaces in a way that the cost function is minimized. RESULTS: With the new automated computerized analyzing system the measurement results were less dependent on the reader's experience, and the variability between readers was less compared with the old manual analyzing system. The measurements were also less time consuming. CONCLUSIONS: The new automated analyzing system will not only greatly increase the speed of measurements but also reduce the variability between readers. It should also reduce the variability between different laboratories if the same analyzing program is used. Furthermore, the new system will probably prevent the problem with drift in measurements over time.

Automation↗
PubMed1997

[Study on immunological pharmacology of keyin granule].

By intragastric keyin granule at the dosage of 1.0-4.0 g/kg.d[-1] for 7-10 days in mice, this drug can enhance the phagocytic function of the macrophages of peritoneal cavity, increase the index of spleen and the clearance rate of i.v. charcoal particles, obviously inhibit the formation of mouse-specific antibody and the delayed cutaneous hypersensitivity (DCH), recover the decrease of ANAE lymphocyte in periphery blood induced by cyclophosphamide. It can also improve the index of immunological organ of immunosuppression mice. These show the immunological regulative function of this drug.

Adjuvants, Immunologic↗
PubMed1997

Hepatocyte growth factor, keratinocyte growth factor, and other growth factor-receptor systems in the lens.

PURPOSE: To examine the expression and function of hepatocyte growth factor (HGF), keratinocyte growth factor (KGF), epidermal growth factor (EGF) and other growth factor-cytokine-receptor systems in lens epithelial cells. METHODS: Reverse transcription-polymerase chain reaction (RT-PCR) and Northern blot analysis were used to examine the expression of messenger RNAs in primary cultured rabbit and human lens cells and in ex vivo rabbit lens tissue. Protein expression and the effect of HGF and KGF on crystallin expression in lens epithelial cells were evaluated by immunoprecipitation and Western blot analysis. The effect of exogenous HGF, KGF, and EGF and of the coculture of lens epithelial cells with corneal endothelial cells on the proliferation of rabbit lens cells in a Transwell system was determined by cell counting. RESULTS: Messenger RNAs and proteins of HGF and KGF were expressed in primary rabbit lens epithelial cells and in ex vivo rabbit lens epithelial tissue. Human lens cells also expressed the mRNAs. Other growth factors and receptor messenger RNAs were also expressed. Hepatocyte and keratinocyte growth factors, and coculture with corneal endothelial cells stimulated proliferation of rabbit lens epithelial cells. In first-passage rabbit lens cells, HGF, KGF, and EGF increased the expression of alpha and beta crystallins. CONCLUSIONS: Hepatocyte and keratinocyte growth factor-receptor systems are expressed in lens cells. HGF and KGF are not expressed in epithelial cells in such tissues as skin, cornea, and lacrimal gland in which fibroblastic and epithelial cells interact in the formation of an organ. Expression of these growth factors in the lens may have evolved because the lens cells are relatively isolated within the anterior chamber of the eye. Our results suggest, however, that growth factors released by the corneal endothelium also could modulate lens functions (aquecrine interactions).

Animals↗
PubMed1996

The Fas-Fas ligand system and other modulators of apoptosis in the cornea.

PURPOSE: Previous studies have suggested that the disappearance of anterior keratocytes after injury to the overlying epithelium is mediated by apoptosis. The authors examined the expression of the apoptosis-related modulators, Fas (receptor), Fas ligand, Bax, Bcl-2, Bcl-XL, and interleukin-1 beta converting enzyme (ICE) in corneal cells as candidate mediators of this response and tested the effect of Fas receptor-stimulating antibody on corneal stromal fibroblast cells in vitro. METHODS: Reverse-transcription-polymerase chain reaction was used to detect FAS, FAS ligand, Bax, Bcl-2, Bcl-XL, and ICE mRNA expression in primary cultures of human corneal epithelial, stromal fibroblast, and endothelial cells. Immunohistochemistry was applied to detect Fas and Fas ligand proteins in fresh-frozen sections of normal human cornea. The effect of FAS-stimulating monoclonal antibody on first-passage stromal fibroblasts was studied using a DNA fragmentation assay, the live-dead assay with fluorescent microscopy, toluidene blue staining with light microscopy, and electron microscopy. RESULTS: FAS, Fas ligand, Bax, Bcl-2, Bcl-XL, and ICE mRNAs are expressed in all three major cell types of the cornea. Fas protein is expressed in corneal epithelial, keratocyte, and endothelial cells in fresh-frozen human cornea. Fas ligand protein, however, was detected in corneal epithelial and endothelial, but not keratocyte, cells. Fas-stimulating antibody induced first-passage stromal fibroblast cell death with morphologic changes and DNA fragmentation consistent with apoptosis. CONCLUSIONS: The Fas system (Fas and Fas ligand) modulators and final common pathway mediators of apoptosis are expressed in corneal cells. The distribution of Fas (epithelial, keratocyte, and endothelial cells) and Fas ligand (epithelial and endothelial cells) protein expression in fresh-frozen corneal tissue suggests that Fas ligand expressed in corneal epithelial and endothelial cells modulates functions in keratocyte cells and, possibly, autocrine-juxtacrine functions in epithelium and endothelium. The Fas-Fas ligand system is expressed in the cornea and could have important functions in normal corneal physiology and in the pathophysiology of corneal disease, including modulation of keratocyte apoptosis after epithelial injury.

Amino Acid Sequence↗
PubMed1995

Transcriptional regulation of the genes encoding cytochromes P450BM-1 and P450BM-3 in Bacillus megaterium by the binding of Bm3R1 repressor to Barbie box elements and operator sites.

We previously reported (Liang, Q., He, J.-S., and Fulco, A.J. (1995) J. Biol. Chem. 270, 4438-4450) that Bm3R1, a repressor regulating the expression of P450BM-3 in Bacillus megaterium, could bind to Barbie box sequences in the 5'-flanking regions of barbiturate-inducible genes. We've now shown that pentobarbital does not inhibit in vitro binding of Bm3R1 to the P450BM-3 and P450BM-1 Barbie boxes (BB3 and BB1), although the palindromic operator sequence (OIII) of P450BM-3 did have a strong competitive effect on such binding. G39E-Bm3R1, a mutant of Bm3R1, did not bind to either Barbie box. In the presence of Bm3R1, portions of the regulatory regions of P450BM-3 and P450BM-1 were protected from DNase I digestion. These included 11 of the 15 base pairs of BB3 plus 7 base pairs 3' to BB3, BB1 plus 16 base pairs 3' to BB1, and, in the 5'-flanking region of P450BM-1, segments covering most of two palindromic sequences (OII and OIII) of 24 and 52 base pairs. These DNase I-protected regions (including OIII) showed considerable sequence identity, especially in a conserved poly(A) motif. Barbiturates did not inhibit binding of Bm3R1 to OI. OII in vitro while G39E-Bm3R1 did not bind. The regulatory effects of Bm3R1 on P450BM-1 and P450BM-3 were also evaluated in vivo using heterologous chloramphenicol acetyltransferase constructs and Western blotting. In the G39E mutant strain, both P450BM-1 and P450BM-3 were constitutively expressed, and the regulatory proteins Bm1P1 and Bm3P1, although still pentobarbital-inducible, had significantly higher basal levels of synthesis. In toto, our results show that Bm3R1 represses both P450BM-1 and P450BM-3 expression and that it may effect this by coordinate binding to operator and Barbie box sequences to produce looping of the P450BM-1 and P450BM-3 regulatory regions through protein-protein interaction.

Bacillus megaterium↗
PubMed1995

The molecular cloning and characterization of BM1P1 and BM1P2 proteins, putative positive transcription factors involved in barbiturate-mediated induction of the genes encoding cytochrome P450BM-1 of Bacillus megaterium.

Analysis of a 1.3-kilobase segment of 5'-flanking DNA from the barbiturate-inducible P450BM-1 gene (CYP106) of Bacillus megaterium revealed two open reading frames. One, BM1P1, encodes 98 amino acids and is located 267 base pairs upstream from the sequence encoding cytochrome P450BM-1 but in the opposite orientation. The second, BM1P2 (88 amino acids), is 892 base pairs upstream from the P450BM-1 coding sequence and in the same coding strand. The expression of BM1P1 and BM1P2 was strongly stimulated in cells grown in the presence of pentobarbital, and the BM1P1 gene product exerted positive control on expression of P450BM-1. When a 177-base pair fragment encompassing the overlapping promoter regions of the P450BM-1 and BM1P1 genes was used as a probe in DNA binding assays, the BM1P1 and BM1P2 gene products and Bm3R1 (the repressor protein regulating the barbiturate-mediated expression of P450BM-3) could bind individually, but the addition of BM1P1 or BM1P2 to a binding mixture containing Bm3R1 completely prevented the appearance of a Bm3R1 binding band. When a 208-base pair fragment containing a Barbie box sequence and located upstream of the 177-base pair fragment was used as a probe, only a Bm3R1 binding band was detected. Although neither BM1P1 and BM1P2 appeared to bind to this 208-base pair fragment, their presence strongly inhibited the binding of Bm3R1 to the same probe. The evidence suggests that BM1P1 and BM1P2 may, in part, act as positive regulatory proteins involved in the expression of the P450BM-1 gene by interfering with the binding of the repressor protein, Bm3R1, to the regulatory regions of P450BM-1.

Amino Acid Sequence↗
PubMed1995

The role of Barbie box sequences as cis-acting elements involved in the barbiturate-mediated induction of cytochromes P450BM-1 and P450BM-3 in Bacillus megaterium.

In a previous publication (He, J.-S., and Fulco, A. J. (1991) J. Biol. Chem. 266, 7864-7869), we reported that a 15-17-base pair DNA sequence (designated a Barbie box element) in the 5'-regulatory regions of cytochrome P450BM-1 and P450BM-3 genes from Bacillus megaterium was recognized by a barbiturate-regulated protein. It is now recognized that essentially all eukaryotic and prokaryotic genes whose 5'-flanking regions are known and that encode barbiturate-inducible proteins contain the Barbie box element. A 4-base pair sequence (AAAG) is found in the same relative position in all Barbie box elements. In B. megaterium, mutation of the Barbie box located in the P450BM-1 gene leads to the constitutive synthesis of cytochrome P450BM-1 and a 10-fold increase of expression of Bm1P1, a small gene located upstream of the P450BM-1 gene, that encodes a putative regulatory protein. Mutation of the P450BM-3 Barbie box significantly increased the expression of both P450BM-3 and Bm3P1 (another small gene located upstream of the P450BM-3 gene that encodes a second putative regulatory protein) in response to pentobarbital induction but left the basal levels unaffected. In gel mobility shift assays, Bm3R1, a repressor of the P450BM-3 gene, was found to specifically interact with the Barbie box sequences of the B. megaterium P450 genes. Mutated Barbie boxes showed a decreased binding affinity for Bm3R1 compared to their wild type (unmutated) counterparts. Barbie box sequences were also shown to specifically interact with putative positive regulatory factors of B. megaterium cells. These putative positive factors were induced by pentobarbital and were also present at high levels during late stationary phase of B. megaterium cell cultures grown in the absence of barbiturates. The mutated Barbie box sequences had greater binding affinity for these positive factors than did unmutated Barbie box sequences. DNase I footprinting analysis of the 5'-flanking region of the P450BM-1 gene revealed that these positive factors protected a segment of DNA covering a portion of the Barbie box sequence and a small flanking region. Similar footprinting experiments with the 5'-flanking region of the P450BM-3 gene failed, however, to unambiguously reveal protected sequences in the Barbie box region. The evidence suggests that the positive factors and Bm3R1 compete with each other for binding to the Barbie box region, especially in the 5'-flanking region of the P450BM-1 gene, and for putative roles in the regulation of transcription from the B. megaterium P450 genes.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1995

An efficient and optimized PCR method with high fidelity for site-directed mutagenesis.

We have developed an efficient method for site-directed mutagenesis using two subsequential rounds of PCR. In this method, PCR conditions are optimized to favor high fidelity of Taq DNA polymerase in the presence of equimolar concentrations of MgCI2 and dNTP in the reaction mixture (pH 5.5-6.2). This method makes use of a pair of universal primers and the multiple cloning site of pUC/M13 vectors. Only one mutagenic primer is required per target site. In the second round of PCR, the 3' extension of the wild-type DNA strand is blocked by the presence of a segment of nonhomologous sequence at its 3' end, and as a consequence, the amplified, full-length DNA fragment is chiefly from the mutant strand. Furthermore, because the mutated DNA fragment has flanking restriction sites different from those of the wild-type DNA fragment, the wild-type DNA fragment is totally excluded in the step involving selective cloning of the mutant DNA fragment. This method was successfully used to introduce four, nonadjacent mutations in the 5' regulatory region of the cytochrome P450BM-3 gene. All 20 analyzed clones from these four cases of mutagenesis carried the desired mutations, and no undesired mutations were observed. We observed that the larger the number of mismatched nucleotide residues in the mutagenic primer, the higher the concentration of MgCI2 was necessary for successful PCR amplification. Our experimental results indicate that this method offers improvements in efficiency, flexibility, and fidelity.

Bacillus megaterium↗
PubMed1995

Surgical treatment of hallux valgus by reconstruction of metatarsal arch and modified McBride operation (40 cases report).

72 feet with hallux valgus among 40 patients treated by reconstruction of metatarsal arch and modified McBride operation are reported in this paper. After an average of 4.5 years of postoperative follow-up, the results showed an overall 9 degrees and 3 degrees correction of the hallux abductus angle and the intermetatarsal angle, respectively. 95% of the cases of bunions disappeared, 66% calli under the heads of the first and second metatarsal disappeared, and 91% patients were satisfied with the changes of their feet appearance.

Adult↗
PubMed1994

[Effects of wuzi yanzong pills on lipid in rats with alcohol-induced liver injury].

Experiments showed that in the rat model of alcohol-induced liver injury, a dosage of the pills (1-2g/kg, ig) could increase the cholesterol level, lower the triglyceride level, and improve the fatty degeneration and necrosis of liver (P < 0.05-0.01). The results suggest that the important mechanism of the pills in protecting and treating alcoholic fatty liver, lies in the regulation of metabolism of the lipid, especially of the triglyceride.

Animals↗
PubMed1993

Dynamic investigation on chromosome aberration of a human retinoblastoma cell line So-Rb50.

G-banding and karyotype analyses of cells in seventeen passages of SO-Rb50 during a long period of culture for about four years were performed. Three chromosome markers 13q14-, 1p36+ and 12p13+ were found. Cells possessed 13q14- reduced to zero after the 200th passage while 1p+ and 12p+ cells increased to 100% after 30 and 200 passages respectively. Abnormal chromosomes, ring chromosomes, chromosome radiuses and double minutes were also observed. These chromosomal changes were more often seen before the 200th passage. The significance of these changes are discussed.

Chromosome Aberrations↗