Biomedical subjects

R Li

Publications and source records attributed to R Li.

At least 127 records · Page 7Linked to original sources

PubMed2001

[Clinical application of three-dimensional spiral CT in the complex maxillofacial fractures].

OBJECTIVE: The aim of this study was to evaluate the clinical application of the three-dimensional spiral CT in the complex maxillofacial fractures. METHODS: A total of 26 patients with complex maxillofacial fractures were examined using spiral CT with the slice thickness of 3 to 5 mm. The surface shaded display (SSD) method was used for reconstruction of the three-dimensional (3D) images. The three-dimensional images of maxillofacial fractures were obtained by using various rotations. Before the three-dimensional images were reconstructed, the drawing and deleting way was used for these mandibular fractures. RESULTS: The method demonstrated clearly the three-dimensional anatomy and their relationships of the fractures; using the drawing and deleting way, location and move condition of mandibular fractures, especially condylar fractures, were showed clearly. CONCLUSION: The three-dimensional CT is important in evaluating complex maxillofacial fractures. It could be used to demonstrate clearly locations and move conditions of complex maxillofacial fractures and operative plans.

Adolescent↗

PubMed2001

[Plasma autoantibodies to heat shock proteins in idiopathic sensorineural hearing loss].

OBJECTIVE: To identify the specificity of autoantibodies to heat shock proteins in idiopathic sensorineural hearing loss (ISNHL) and to evaluate the existence of autoantibodies. METHOD: Plasma samples were obtained from patients with ISNHL (n = 41), systemic lupus erythematosus (n = 22), and normal controls (n = 30). Plasma autoantibodies to heat shock proteins (HSPs) were detected by Western blot using purified recombinant human HSP27, HSP60, HSP71 HSP90 alpha and HSP90 beta as antigen respectively. RESULT: In the ISNHL, the incidence of plasma autoantibodies to recombinant human HSP27, HSP60, HSP71, HSP90 alpha and HSP90 beta were 12.1%, 7.3%, 51.2%, 4.8% and 0% respectively. The incidence of autoantibody to HSP71 was significantly greater than that in systemic lupus erythematosus and in normal controls (P < 0.01). CONCLUSION: These results indicated that the autoantibody to HSP71 was main autoantibodies to HSPS in ISNHL and its presence might serve as a marker for an autoimmune etiology of these patients' hearing loss.

Adult↗

PubMed2001

[Influences of the mobile phase constitution, salt concentration and pH value on retention characters of proteins on the metal chelate column].

The effects of the nature and concentration of salts, pH value and competitive eluent in the mobile phase on the protein retention have been systematically investigated. A mathematical expression describing the protein retention in metal chelate chromatography has been derived. It is proposed that the eluting power of the salt solution can be expressed by the eluent strength exponent epsilon. According to the retention characters of protein under different chromatographic conditions, the interaction between the various metal chelate ligands and proteins is discussed. The protein retention on the metal chelate column is a cooperative interactions of coordination, electrostatic and hydrophobic interaction. For the strong combined metal column with proteins such as IDA-Cu, the coordination is the most important, and the electrostatic interaction is secondary in chromatographic process. However, for the weak combined metal columns with proteins such as IDA-Ni, IDA-Co and IDA-Zn, the electrostatic interaction between the metal chelate ligands and proteins is the chief one, while the coordination is the next in importance. When the mobile phase contains high concentration of salt which can't form complex with the immobilized metal, the hydrophobic interaction between the protein and stationary phase will be increased. As the interaction between the metal chelate ligand and proteins relates to chromatographic operating conditions closely, different elution processes may be selected for different metal chelate columns. The gradient elution is generally performed by the low concentration of salt or different pH for weakly combined columns with proteins, however the competitive elution procedure is commonly utilized for strongly combined column. The experiment showed that NH3 is an excellent competitive eluent. It isn't only give the efficient separation of proteins, but also has the advantages of cheapness, less bleeding of the immobilized metals and ease of controlling NH3 concentration. The interaction between the metal chelate ligand and proteins and the selectivity of metal chelate chromatography can be changed through changing chromatographic conditions.

Chelating Agents↗

PubMed2001

[A study on the breeding of new Ganoderma varieties by UV induced mutagenesis].

UV induced mutagenesis of Ganoderma's protoplast was carried out. By crude screen and careful screen, we obtained two mutants, 43020# and 43026$, whose dry weight and polysaccharides contents are higher than original strain. Results of continued cultivation for 10 generation on PDA slants and successive tests of shaking bottles, and successive 3 time pilot scale tests at 3 tons, showed that these two mutants are excellent strains with steady properties, high production and high content of polysaccharides. This study has provided a rapid and effective method for breeding of Ganoderma varieties which is suitable to industrial fermentation.

Breeding↗

PubMed2001

[Application of FAM networks in recommendation of mobile phase for RP-HPLC].

AIM: To establish expert system to recommend solvent strength in RP-HPLC by using FAM (fuzzy associate memorizer) networks. METHODS: Symbolic rules reflecting the quantitative relationship among molecular structure, capacity factors and solvent strength in RP-HPLC were extracted from trained radial basis function networks. Then FAM networks consisting of these rules were built to recommend mobile phase strength for RP-HPLC. RESULTS: The validation results of the system by monocomponent and mutilcomponent drug samples were satisfied. CONCLUSION: The mobile phase recommendation system for RP-HPLC analysis of drugs showed reliable performance.

Chromatography, High Pressure Liquid↗

PubMed2001

[The significance of nuclear factor kappa Bp65 (NF kappa Bp65) expression on the vascular endothelial cells of rectum adenocarcinoma of human].

OBJECTIVE: This study inquired into the mechanism of cancer vascular metastasis. METHODS: The immunohistochemical method was adopted in determining the expression of intercellular adhesion molecule-1 (ICAM-1) and nuclear factor kappa B (NF kappa Bp65) on the peritumoral rectum tissues and metastatic lymph nodes of 8 patients and on the rectum tissues and lymph nodes of 5 normal human subjects. Also, the method of in situ hybridization was employed in detecting the binding site of NF kappa Bp65 on vascular endothelial cells. RESULTS: It was found that the proteins of ICAM-1 and NF kappa Bp65 were expressed on the vascular endothelial cells of the rectum adenocarcinoma patients, and there was a NF kappa B binding consensus sequences on ICAM-1 promoter in the vascular endothelial cells of the rectum adenocarcinoma patients. When DIG-AKP labeled 38-bp oligonucleotide probe was used, there was no expression of ICAM-1 and NF kappa Bp65 on the vascular endothelial cells of the normal human lymph node and rectum tissues. CONCLUSION: The above data suggest that the activation of ICAM-1 promoter may critically depend on NF kappa Bp65 homodimers or heterodimers binding to a variant kappa B site on the vascular endothelial cells of human rectum adenocarcinoma. These may indicate the potential roles of NF kappa B in cancer metastasis, thus giving clues to the development of a novel anti-metastasis strategy.

Adenocarcinoma↗

PubMed2001

[Transforming growth factor-beta can induce differentiation of hypertrophic chondrocytes into osteoblast-like cells in epiphyseal plate].

OBJECTIVE: To investigate the effect of transforming growth factor-beta (TGF-beta) on the differentiation of hypertrophic chondrocytes in epiphyseal plate in order to understand its role in the mechanism of bone and cartilage formation. METHODS: We observed the effect of TGF-beta in varied time and dosage on the differentiation of hypertrophic chondrocytes in embryonic chick femora which were cultured in serum-free medium, using histochemical staining to detect the expression of alkaline phosphatase (ALP) and immunohistochemical staining to detect the expression of type I collagen and fibronectin. RESULTS: TGF-beta enabled the chondrocytes to express type I collagen and fibronectin, and it enhanced the expression of ALP in hypertrophic zone. Time-effect and dosage-effect relationships were observed. CONCLUSION: TGF-beta can induce the differentiation of hypertrophic chondrocytes into osteoblast-like cells in epiphyseal plate of embryonic chick femora. The inducing effect might be closely related to time and dosage of TGF-beta.

Animals↗

PubMed2001

[Study on the construction of DYS385 allelic ladder and the genotype distribution in two populations].

OBJECTIVE: We have designed a new method to produce standard DYS385 allelic ladder in order to solve the problem of the accuracy and standardization of STR-PCR typing in forensic practice. METHODS: Nine different PCR amplified DYS385 allelic fragments were isolated from the gel, eluted into the distilled water and reamplified by PCR. The purified allelic fragments were then blunt-end subcloned individually into the pUC plasmid vectors and transfected into competent E. coli DH5 alpha cells. The sequencing results confirmed that the size and the constructure of the inserts were correct. The recombinant plasmids DNA with 9 inserts were then used as templates for reamplification to generate DYS385 standard ladder. RESULTS: A large quantity of standard DYS385 allelic ladder was obtained, with which the genetic polymorphisms of DYS385 locus both in Chinese Han and German populations were studied. CONCLUSION: The STR standard ladder constructed by this method has high value in the forensic application, and the DYS385 locus is robust for forensic analysis.

Alleles↗

PubMed2001

[The role of immune enhanced enteral nutrition on plasma amino acid, gut permeability and clinical outcome (a randomized, double blind, controlled, multi-center clinical trail with 120 cases)].

OBJECTIVE: To evaluate the role of arginine, RNA and omega 3 fatty acid enriched enteral nutrition. METHODS: The study was designed as a prospective, randomized, double blind, multi-central trial. It was an isocaloric and isonitrogenous intake in both groups. The protocol was approved by the Ethic Committee and, written informed consents were obtained. RESULTS: There were 120 patients enrolled in this protocol. After data were input to computer, open the code. 118 out of 120 patients completed the study and, 2 of them were dropped out. One is because the nasal jejunum tubes dropped and not willing to be replaced. Second patient had fistula of anastomosis on 4th days after operation. There were finally 60 patients in the study group and 58 in the control group. There were no liver or renal functions damage and, obvious adverse in both groups. Plasma amino acid profile: There was significant difference (delta) of plasma arginine levels pre- and after study [(33.7 +/- 58.5) mumol/L vs (-2.4 +/- 30.7) mumol/L] (P = 0.004). Intestinal Permeability (lactulose/mannitol ratio): The differences (delta) of lactulose/mannitol ratio pre- and after the study were 0.017 +/- 0.012 in study group and, 0.027 +/- 0.016 in control group. (P = 0.047). Immunological markers: Humoral immunity: The differences of IgM levels pre- and after the study were (0.6 +/- 0.4) g/L in study group and, (0.2 +/- 0.4) g/L in control group(P = 0.006). Cellular immunity: The differences (delta) of CD3 levels pre- and after the study were (3.8 +/- 5.2)% in study group and (0.3 +/- 6.5)% in control group (P = 0.01). In CD4, (3.4 +/- 5.3)% in study group and, (-0.3 +/- 5.7)% in control group (P = 0.032). Clinical Outcomes: There was no infection-related in study group and, 2 abdominal infection patients in control group. No significant difference was found between groups (P = 0.46). The hospital stays were (13 +/- 2.5) days in study group and, (14.5 +/- 3.0) days in control group (P = 0.004). The cost for full hospitalization was (15,122 +/- 6,279) Yuan in study group and, (17,403 +/- 7,091) Yuan in control group. There was 2,281 Yuan lower in study group (P = 0.07). The costs for nutritional drugs were (1,383 +/- 242) Yuan in study group and, (707 +/- 111) Yuan in control group. The difference was 676 Yuan higher in study (P = 0.001). CONCLUSION: Immune enhanced enteral nutrition had better plasma arginine level, intestinal permeability marker, IgM, CD3 and CD4. Also had less hospital stay and, less totaled hospital cost in study group.

Adult↗

PubMed2001

[Determination of sulfamethoxazole in compound sulfamethoxazole tablet by first derivative ratio spectrometry].

The first derivative ratio spectrometry is used for the determination of sulfamethoxazole in compound sulfamethoxazole tablet. According to the first derivative ratio spectrum of sulfamethoxazole, peak-zero method is applied for the determination at 251 nm. There is a good linear correlation between the first derivative ratio spectrum value and concentration (1-15 micrograms.mL-1) for the method that can eliminate the disturbance of trimethoprim, and no difference while comparing the method with pharmacopoeia method (P > 0.05).

Spectrophotometry, Ultraviolet↗

PubMed2000

Characterization of a novel trans-activation domain of BRCA1 that functions in concert with the BRCA1 C-terminal (BRCT) domain.

Mutations in the breast cancer susceptibility gene, BRCA1, account for a significant proportion of hereditary breast and ovarian cancers. The BRCA1 C-terminal (BRCT) domain, which can activate transcription when fused to a heterologous DNA binding domain, is required for BRCA1 function in suppression of tumorigenesis. Here, we provide evidence for a new activation domain in BRCA1 that lies adjacent to the BRCT domain. We name the two domains AD1 and AD2, respectively. Like AD2, the newly discovered AD1 can act independently as an activation domain in both yeast and human cells. However, unlike AD2, AD1 activity in mammalian cells is cell type context-dependent. Furthermore, combination of these two domains in mammalian cells can result in a robust synergy in transcriptional activation. A highly conserved coiled-coil motif in AD1 is required for the cooperative transcription activation. Interestingly, the functional cooperativity between AD1 and AD2 is absent in certain breast and ovarian cancer cell lines, although each domain can still activate transcription. Therefore, the differential and cooperative actions of the two activation modules may contribute to the heterogeneous risk of BRCA1 mutations in different tissues.

Amino Acid Sequence↗

PubMed2000

A functional comparison of BRCA1 C-terminal domains in transcription activation and chromatin remodeling.

The BRCA1 C-terminal (BRCT) domain is present in a number of proteins that are involved in various aspects of chromosomal events. The BRCT domain of BRCA1 is important for its function in DNA repair and transcriptional activation. When tethered to chromosomal DNA, this region of BRCA1 is capable of inducing changes in chromatin structure. Despite the sequence homology and functional proximity shared by the BRCT-containing proteins, it is not clear whether different BRCT domains confer a common biochemical activity. Much less is known about the functional significance of the characteristic amino acid residues in the BRCT motif. Here, we show that chromatin remodeling and transcription activation is not a common feature of BRCT domains. However, the BRCT domain of the multi-functional repressor-activator protein 1 (RAP1) can activate transcription and remodel chromatin in a manner similar to that shown for the BRCA1 BRCT domain. Most of the conserved amino acid residues in the second BRCA1 BRCT domain are essential for its function in transcriptional activation. In contrast, mutations of many analogous amino acid residues in the RAP1 BRCT domain greatly elevate the transcriptional activity. These data indicate that the conserved residues in these two BRCT domains may play different roles in transcriptional activation.

Amino Acid Sequence↗

PubMed2000

Regulation of Ets function by protein - protein interactions.

Ets proteins are a family of transcription factors that share an 85 amino acid conserved DNA binding domain, the ETS domain. Over 25 mammalian Ets family members control important biological processes, including cellular proliferation, differentiation, lymphocyte development and activation, transformation and apoptosis by recognizing the GGA core motif in the promoter or enhancer of their target genes. Protein - protein interactions regulates DNA binding, subcellular localization, target gene selection and transcriptional activity of Ets proteins. Combinatorial control is a characteristic property of Ets family members, involving interaction between Ets and other key transcriptional factors such as AP-1, NFkappaB and Pax family members. Specific domains of Ets proteins interact with many protein motifs such as bHLH, bZipper and Paired domain. Such interactions coordinate cellular processes in response to diverse signals including cytokines, growth factors, antigen and cellular stresses.

Amino Acid Motifs↗

PubMed2000

An isoleucine-based allosteric switch controls affinity and shape shifting in integrin CD11b A-domain.

In response to cell activation signals, integrins switch from a low to a high affinity state. Physiologic ligands bind to integrins through a von Willebrand Factor A-type domain. Crystallographic studies revealed two conformations of this domain, "closed" and "open." The latter crystallizes in complex with a pseudoligand or ligand, suggesting that it represents the high affinity state; data linking structure and activity are lacking however. In this communication, we expressed stable low and high affinity forms of integrin CD11b A-domain and determined their binding isotherms and crystal structures. The low affinity form, generated by deleting an N-terminal extension extrinsic to the domain, did not bind to physiologic ligands, and crystallized in the closed conformation. The high affinity form was generated by either deleting or substituting an invariable C-terminal Ile(316), wedged into a hydrophobic socket in the closed form, but displaced from it in the open structure. Both mutants crystallized in the open conformation, and the Ile(316) --> Gly-modified integrin displayed high affinity. Structural differences between the low and high affinity forms were detected in solution. These data establish the structure-function correlates for the CD11b A-domain, and define a ligand-independent isoleucine-based allosteric switch intrinsic to this domain that controls its conformation and affinity.

Allosteric Regulation↗

PubMed2000

A novel evidence of different mechanisms of lithium and valproate neuroprotective action on human SY5Y neuroblastoma cells: caspase-3 dependency.

Both lithium and valproate have been used in the treatment of manic-depressive illness with very limited understanding of their therapeutic mechanism of action. Recent literature suggests that blocking of potassium channels may be a common therapeutic mechanism of many antidepressant agents. To determine whether the commonly used antimanic agents could prevent potassium efflux-induced cell damage and apoptosis and the underlying mechanisms, we treated SH-SY5Y human neuroblastoma cells with the potassium ionophore, valinomycin (2-100 microM) and observed cell shrinkage, mitochondria damage, a significant increase in of lactate dehydrogenase (LDH) activity and caspase-3 protein expression. Cells treated with lithium (0.5-3 mM) or valproate (0.07-1.4 mM) alone produced no apoptotic morphological and biochemical changes while both mood stabilizers pretreatment reduced or prevented the apoptotic morphological changes. However, valinomycin-induced caspase-3 elevation was only prevented by lithium pretreatment while both lithium and valproate attenuated valinomycin-induced LDH release. Our results suggest that lithium and valproate share a common neuroprotective action against potassium efflux-induced cell apoptosis with different mechanisms.

Antimanic Agents↗

PubMed2000

Expression and structural characterization of the recombinant human doppel protein.

The doppel protein (Dpl) is a newly recognized prion protein (PrP)-like molecule encoded by a novel gene locus, prnd, located on the same chromosome as the PrP gene. To study the structural features of Dpl, we have expressed recombinant human Dpl corresponding to the putative mature protein domain (residues 24-152) in Escherichia coli. The primary structure of the recombinant Dpl 24-152 was characterized using gel electrophoresis, N-terminal Edman sequencing, matrix-assisted laser desorption ionization mass spectrometry, and electrospray ionization mass spectrometry. Dpl 24-152 was shown to contain two disulfide bonds (Cys94-Cys145 and Cys108-Cys140). The secondary structure of Dpl was analyzed using far-UV circular dichroism spectroscopy. Dpl 24-152 was found to be an alpha-helical protein having a high helical content (40%). Dpl 24-152 exhibited characteristics of a thermodynamically stable protein that undergoes reversible and cooperative thermal denaturation. In addition, Dpl was found to be soluble and sensitive to proteinase K digestion. Therefore, Dpl 24-152 possesses biochemical properties similar to those of recombinant PrP. This study provides knowledge about the molecular features of human Dpl that will be useful in further investigation into its normal function and the role it may play in neurodegenerative diseases.

Amino Acid Sequence↗

PubMed2000

Cellular gangliosides promote growth factor-induced proliferation of fibroblasts.

Cell surface gangliosides have been proposed as modulators of transmembrane signaling. In this study, we used two complementary approaches to investigate the function of cellular gangliosides in the response of mammalian fibroblasts to growth factors. First, inhibition of glucosyl ceramide synthase by a new specific inhibitor of d-l-threo-1-phenyl-2-hexadecanoylamino-3 -pyrrolidino-1-propanol-HC l (glucosylceramide synthase), which depletes cellular gangliosides at a concentration of 1 microm without causing an increase in ceramide levels, blocked epidermal growth factor-stimulated proliferation of fibroblasts. Similarly, responses to several other growth factors that activate receptor tyrosine kinases, including fibroblast growth factor, insulin-like growth factor-I, and platelet-derived growth factor, were inhibited by 50-100%. Conversely, enrichment of cellular gangliosides by preincubation of the mouse and human fibroblasts with exogenously added gangliosides enhanced growth factor-elicited cell proliferation. Novel findings of this study, distinguishing it from previous similar studies, include differential effects of preincubation versus continuous incubation of cells with gangliosides on growth factor-dependent cell proliferation and the growth factor-like action of NeuNAc alpha 2-3Gal beta 1-3GalNAc beta 1-4(NeuNAc alpha 2-3)Gal beta 1-4Glc beta 1-1Cer when cells are pretreated with the ganglioside.

3T3 Cells↗

PubMed2000

Mitosis: shutting the door behind when you leave.

Yeast cells must segregate sister chromosomes to the opposite sides of the bud neck during mitosis. A pathway has been identified, involving a small GTPase, which prevents the onset of cytokinesis until one of the spindle poles has migrated into the bud.

Cell Division↗