Biomedical subjects

R Chen

Publications and source records attributed to R Chen.

At least 163 records · Page 9Linked to original sources

PubMed2001

The effect of electro-acupuncture on motor function recovery in patients with acute cerebral infarction: a randomly controlled trial.

UNLABELLED: The aim of this study is to investigate the effect of electro-acupuncture treatment in acute phase of cerebral infarction on the motor functions. In this randomly controlled trial, 86 patients were allocated to two groups, the experimental group given clinical and electro-acupuncture treatments for a period of 4 weeks, and the control group given clinical treatment plus active and/or passive functional exercise. The result showed that the level of impairment and disability in both groups were improvement according to the Chinese Stroke Scale, Brunnstrom-Fugl-Meyer score, and Barthel Index throughout the study and 3 months after. The motor functions and the activities of daily living (ADL) were improved significantly in the electro-acupuncture group as compared with the control group (P < 0.05). Also, the results showed greater reduction of neurological deficit in the electro-acupuncture group than in the control group. CONCLUSION: Early acupuncture treatment for acute stroke patients may improve motor functions, and consequently the activities of daily living.

Acupuncture Therapy↗

PubMed2001

[Effects of IL-8 on neutrophils under fluid shear].

OBJECTIVE: In order to elucidate the effect of IL-8 on neutrophils in a systematic and all-round way, we introduced an important physiological environment of neutrophils, fluid flow, into this study on the changes in some responses of neutrophils to IL-8 and the inter relationship of those responses under the conditions of different patterns of flow field. METHODS: After using IL-8 and steady flow or sinusoidal-oscillate fluid shear rate simultaneously acting on separated neutrophils for one minute, we measured the expression of CD18, CD62L and the F-actin content with flow cytometry and measured the free calcium concentration inside cells ([Ca2+]i) with the fluorescent stain Fura2/AM using the fluorescent spectrophotometer. RESULTS: It was found that flow shear stress could influence the expression of surface adherence molecule of neutrophils under the action of IL-8. CD18 surface expression increased, and CD62L shed under different flow shear rates, but no significant relationship of these changes with the intensity and pattern of shear stress was noted. On the other hand, the F-actin content in neutrophils under the action of shear stress and IL-8 decreased significantly at low shear rate and then gradually increased at high shear rate (600s -1) to the control value (without shear). The [Ca2+]i concentration under the action of shear stress and IL-8 decreased significantly at low shear rate followed by a quick increase at high shear rate. CONCLUSION: The flow shear stress can influence the activation effects of IL-8 on neutrophils and regulate the magnitude of neutrophil reactions to a great extent, and among these reactions, the change of [Ca2+]i concentration is the most sensitive one and the greatest one. This is in consistence with its second messenger role in the signal transduction pathway. Our results could serve as a basis on which to understand better the mechanism of inflammatory reaction wherein the neutrophils under flow condition of blood are involved.

Actins↗

PubMed2001

[A survey of oral health status of the elderly individuals in Chengdu of China].

OBJECTIVE: The aim of this survey is to investigate the oral health status of the oldsters over 65-year-old in Chengdu of China. METHODS: The oral health status, including oral hygiene, caries, periodontal diseases and the tooth loss of 468 elderly individuals over 65 years old were surveyed and analyzed. RESULTS: It was found that all these older individuals brushed their teeth everyday, but most of them had tooth decay, gingivitis and periodontitis. About 7.47% of them were edentulous, and 2.56% of them were half edentulous. The masticatory ability of most of them declined and the chewing ability of them was low. CONCLUSION: The oral health status of these elderly individuals in Chengdu is poor. It is therefore necessary to improve the health status of this population.

Aged↗

PubMed2001

[Application of voice acoustic analysis in microlaryngoscopic surgery].

OBJECTIVE: To evaluate the relationship between the effect of microlaryngoscopic surgery of vocal polyp and the change of all-parameters. METHOD: Acoustic parameters of 80 patients with vocal polyp were measured by Dr. Speech Sciente for Windows, and analyzed preoperatively and postoperatively. RESULT: The jitter, shimmer and NNE were different significantly between preoperative and postoperative, the NNE and shimmer were more sensitive than jitter. CONCLUSION: The NNE and shimmer of acoustic parameter are objective parameter to evaluate the effect of the microlaryngoscopic surgery of vocal polyp.

Adolescent↗

PubMed2001

[Extraction of DNA from environmental samples and construction of mixed genomic DNA libraries].

A method has been developed for extracting and purifying genomic DNA from environmental samples. In this method, an environmental sample is treated first by grinding and freezing/thawing and subsequently by SDS/proteinase K-based DNA extraction. The yields of purified DNA from three samples used in this study ranged from 2 to 16 micrograms per gram of dry sample. Mixed genomic DNA libraries for two of the environmental samples were constructed by inserting restriction fragments (3-8 kb) of the purified DNAs into plasmid pUC18 and transforming E. coli DH5 alpha with the resultant plasmids. Approximately 10(3) to 10(4) insert-containing clones were obtained from 1 g of each sample. Clone libraries were analyzed by DNA sequencing and gene annotation. Among 20 randomly-selected clones, 14 contained an insert whose sequence had not been reported while the rest had an insert of either E. coli or vector origin. A search of sequence databases using the end sequences of each of the foreign inserts showed that each sequence was part of a gene encoding, in most cases, a predictable function. Our results are of significance to the collection, investigation and exploitation of the genes of uncultured microorganisms.

Amino Acid Sequence↗

PubMed2001

[Cloning and DNA sequencing of Bacillus pumilus endo-1,4-beta-glucanase gene].

Bacillus pumilus S-27 screened from marine environment produces an extracellular endo-1,4-beta-glucanase. The enzyme has its optimal activity at pH 5.0-7.0 and 55 degrees C and still retained 79.0% of it at pH 9.0. The gene encoded this endo-1,4-beta-glucanase was cloned and sequenced. The structural gene contained an open reading frame of 1980 bp, corresponding to 660 amino acids, the amino acid sequence of this enzyme is very close to that of an EG of C. cellulovorans and an EG of Bacillus sp. KSM-522, all belong to the cellulase family E2.

Amino Acid Sequence↗

PubMed2001

[Growth and osteogenesis characteristics of cultured rat marrow stromal cells under bone induction condition].

OBJECTIVE: To investigate the growth and osteogenesis characteristics of cultured rat marrow stromal cells(rMSCs) under bone induction condition. METHODS: rMSCs were isolated from adult rat using density gradient separation method. The rMSCs attachment formed soon after seeding and grew into colonies with the appearance of fibroblastic cells. The osteogenic induction compound of Dex(10(-8) mol/L), beta-GP(10 mmol/L) and AA(50 micrograms/ml) was added to different passaged rMSCs and the proliferation and osteogenic differentiation of them was observed. RESULTS: The induction compound had strong effect on promoting proliferation, especially on that of further passaged rMSCs, and its stimulation effect on osteogenesis was also well proved with the expression of alkaline phosphatase (ALP) rising after one-week induction. Further subculturing from P1 to P6 led to the increase of proliferation activity of rMSCs. After three-week induction, mineral deposits appeared in the culture. CONCLUSION: The lower expression of ALP in P1 rMSCs and the increase of it in further passages or under induction condition suggest the rMSCs in our culture system are mainly undifferentiated osteoprogenitors.

Alkaline Phosphatase↗

PubMed2001

[Relations of electrolytes to the by-product CHCl3 produced in electrochemical disinfection].

OBJECTIVE: To investigate the relation of electrolytes(NaCl, Na2SO4) to the by-product CHCl3 produced in the electrochemical disinfection process. METHODS: Taking filtering water, we used the graphite and Ti (matrix)-Ti as electrodes, adjusted the current sample for analysis in different time, and determined the production of CHCl3 under different conditions. RESULTS: Na2SO4 had no effect on the production of CHCl3 in the electrolysis(P > 0.05). but NaCl had the effect and the higher the concentration of Cl- was, the more the production of CHCl3 increased. The production of CHCl3 increased with the length of electrolysis time, and it exceeded the national standard after 10 minutes' electrolysis using Ti (matrix)-Ti as electrodes. When graphite was used as electrodes, the production of CHCl3 was much less. CONCLUSION: Na2SO4 has no effect on the production of CHCl3. Our suggestion is that graphite should be used as the electrodes for electrochemical disinfection of drinking water.

Chloroform↗

PubMed2001

[Application of artificial neural network to simultaneous spectrophotometric determination of Cu, Co and Ni].

By means of artificial neural network and Levenberg-Marquardt back-propagation train algorithm, the three-component metal coordinate compounds of PAR-Cu, Co, Ni were determined simultaneously, in which the spectra overlapped. In 452-552 nm, the absorbance(A) at 14 wavelength were taken as character of artificial neural network, and samples were arranged by method of orthogonal design. The mean recovery of Cu, Co, Ni were 99.96%, 99.99% and 99.97% respectively. The RSD of the results were 0.1%, 0.2% and 0.1% respectively. The results were better than those of other networks in training speed and the accuracy. In conclusion, the new network spectrophotometry is a good choice for resolving multicomponent.

Cobalt↗

PubMed2001

[The structures and characteristic infrared spectra of beta-DDB and its derivatives].

The characteristic infrared bands of the 3, 4-methylenedioxy-5-methoxybenzoate, 6-Br-3, 4-methylenedioxy-5-methoxybenzoate, beta-DDB (6, 6'-dimethoxy-4, 5, 4', 5'-dimethylenedioxy-2, 2'-dimethoxycarbonylbiphenyl) and its five derivatives were assigned. The effects of the substituents of these compounds on their IR data were discussed. The results indicated the varying of ester alkyl mainly influences the C=O double band stretching mode, but has little effects on the C=C double band stretching mode of the phenyl. When the H atom was substituted by other substituents, the absorptions of the C=O and C=C both changed.

Biphenyl Compounds↗

PubMed2000

Functionally discrete mimics of light-activated rhodopsin identified through expression of soluble cytoplasmic domains.

Numerous studies on the seven-helix receptor rhodopsin have implicated the cytoplasmic loops and carboxyl-terminal region in the binding and activation of proteins involved in visual transduction and desensitization. In our continuing studies on rhodopsin folding, assembly, and structure, we have attempted to reconstruct the interacting surface(s) for these proteins by inserting fragments corresponding to the cytoplasmic loops and/or the carboxyl-terminal tail of bovine opsin either singly, or in combination, onto a surface loop in thioredoxin. The purpose of the thioredoxin fusion is to provide a soluble scaffold for the cytoplasmic fragments thereby allowing them sufficient conformational freedom to fold to a structure that mimics the protein-binding sites on light-activated rhodopsin. All of the fusion proteins are expressed to relatively high levels in Escherichia coli and can be purified using a two- or three-step chromatography procedure. Biochemical studies show that some of the fusion proteins effectively mimic the activated conformation(s) of rhodopsin in stimulating G-protein or competing with the light-activated rhodopsin/G-protein interaction, in supporting phosphorylation of the carboxyl-terminal opsin fragment by rhodopsin kinase, and/or phosphopeptide-stimulated arrestin binding. These results suggest that specific segments of the cytoplasmic surface of rhodopsin can adopt functionally discrete conformations in the absence of the connecting transmembrane helices and retinal chromophore.

Amino Acid Sequence↗

PubMed2000

Construction and structural modeling of a single-chain Fv-asparaginase fusion protein resistant to proteolysis.

In this study, we construct a fusion protein composed of L-asparaginase (ASNase; from Escherichia coli AS 1.357) and a protective single-chain Fv (scFv), which was selected from a phage-display scFv library from our previous studies. The antibody moiety of the fusion protein was fused to the N-terminus of the enzyme moiety via a linker peptide, (Gly(4)Ser)(6). Recombinant plasmid pET-SLA was constructed to express scFv-ASNase fusion to high levels in E. coli and the expressed product was found to form inclusion bodies. We obtained a soluble fusion protein by refolding and purification. The soluble fusion protein exhibited about 82% of the enzymatic activity of the native ASNase at the same molar concentration, and had a K(m) value similar to that of the native enzyme for the substrate L-asparagine. Importantly, the fusion protein was more stable than native ASNase. In addition: (1) following treatment with trypsin, alpha-chymotrypsin, and rennet, at 37 degrees C for 30 min, scFv-ASNase fusion retained 94.0%, 88.8%, and 84.5% of its original activity, respectively, whereas native ASNase became inactive; and (2) ScFv-ASNase fusion had a much longer in vitro half-life (9 h) in serum than the native enzyme (2 h). The three-dimensional structure of the fusion protein was obtained by modeling with the Homology and Discover modules of the INSIGHT II software package. On the basis of the structural evidence and biochemical properties, we propose that the scFv moiety of the fusion protein may confer ASNase moiety resistance to proteolysis as a result of both steric hindrance and a change in the electrostatic surface of the enzyme.

Asparaginase↗

PubMed2000

A highly specific monomeric isocitrate dehydrogenase from Corynebacterium glutamicum.

The monomeric isocitrate dehydrogenase (IDH) of Corynebacterium glutamicum is compared to the topologically distinct dimeric IDH of Escherichia coli. Both IDHs have evolved to efficiently catalyze identical reactions with similar pH optimum as well as striking specificity toward NADP and isocitrate. However, the monomeric IDH is 10-fold more active (calculated as kcat/Km.isocitrate/Km.NADP) and 7-fold more NADP-specific than the dimeric enzyme, favoring NADP over NAD by a factor of 50,000. Such an extraordinary coenzyme specificity is not rivaled by any other characterized dehydrogenases. In addition, the monomeric enzyme is 10-fold more specific for isocitrate. The spectacular substrate specificity may be predominantly attributed to the isocitrate-assisted stabilization of catalytic complex during hydride transfer. No significant overall sequence identity is found between the monomeric and dimeric enzymes. However, structure-based alignment leads to the identification of three regions in the monomeric enzyme that match closely the three motifs located in the central region of dimeric IDHs and the homologous isopropylmalate dehydrogenases. The role of Lys253 as catalytic residue has been demonstrated by site-directed mutagenesis. Our results suggest that monomeric and dimeric forms of IDHs are functionally and structurally homologous.

Alcohol Oxidoreductases↗

PubMed2000

Characterization of l-asparaginase fused with a protective ScFv and the protection mechanism.

A fusion protein of the protective scFv linked to the C-terminus of ASNase via (Gly(4)Ser)(6) peptide was constructed. The ASNase-scFv fusion protein expressed in Escherichia coli exists mainly in the form of inclusion bodies, and a small amount of it was soluble. The soluble form was purified by four-step purification and it has been demonstrated that ASNase-scFv fusion exists as a dimer. By assay of the stability against proteolysis, the ASNase-scFv fusion was found to be more stable than native ASNase but less stable than scFv-ASNase fusion. The results of immunological assay indicated that the immunogenicity of the fusion proteins increased while their binding capacity with the anti-ASNase serum decreased by comparison to the native ASNase. Moreover, here the comparison of the basic physical and chemical properties of the ASNase-scFv fusion, scFv-ASNase fusion, and native ASNase is presented. Based on the structural evidence and the biochemical analysis described in this paper, the protection mechanism proposed in our previous study was further supported. The scFv moiety of the fusion protein may confer the ASNase moiety resistance to proteolysis as a result of both steric hindrance such as blocking the cleavage sites of trypsin and a change in the electrostatic potential surface of the enzyme.

Animals↗

PubMed2000

Role of organic cation transporters in the renal secretion of nucleosides.

The mammalian kidney eliminates toxic substances from the body, in part via secretion by the organic cation transporters (OCT) or organic anion transporters. Nucleosides are nitrogenous heterocycles that are often secreted by human and other animal kidneys. Previous experiments have shown that 2'-deoxytubercidin (7-deazadeoxyadenosine, dTub) is secreted by the mouse kidney via a cimetidine-sensitive OCT (Nelson et al., Biochem Pharmacol 32: 2323-2327, 1983). Experiments reported herein demonstrated that the cloned rat kidney rOCT1 transports dTub, cytosine arabinoside, 2-chlorodeoxyadenosine, and azidothymidine when expressed in the Xenopus laevis oocyte translation system. Although rOCT2 is 67% identical with rOCT1 in its amino acid sequence, rOCT2 does not mediate the uptake of these nucleosides. Uptake of dTub mediated by rOCT1 was pH-dependent in a manner suggesting that the positive charged moiety of dTub may be the true substrate. Protons acted as competitive inhibitors for the rOCT1-mediated uptake of dTub or tetraethylammonium (TEA), with K(i) values corresponding to a pH of about 6.1. TEA and dTub mutually inhibited the uptake of one another by rOCT1, competitively, with K(i) values approximately the same as their respective K(m) values. These findings suggest that protons, dTub, and TEA act at a common site on rOCT1, and that rOCT1 participates in the renal secretion of dTub and other nucleosides.

Animals↗

PubMed2000

Characterization and transcriptional profiles of two rice MADS-box genes.

The plant MADS-box gene family plays a key role in plant development, especially in flower development. We designed degenerate primer according to the MADS-box conserved region and isolated two cDNA from rice, FDRMADS6 and FDRMADS7, which are homologous to AP1. RT-PCR expression analyses by using total RNA isolated from root, shoot and flower showed that the FDRMADS6 transcript was detectable only in flower while FDRMADS7 was expressed in all three tissues. In situ hybridization experiments indicated that at the early stage of rice flower development, the transcripts of FDRMADS6 and FDRMADS7 were detected in the spikelet apical meristem, which were same as AP1. At the late stage, when flower organ primordia started differentiating, the expression of FDRMADS6 appeared to be specifically localized in developing stamens and the pistil primordia, while the transcripts of FDRMADS7 were detectable abundantly throughout the organ primordia. Our results suggest the two MADS-box genes may be members of the AP1 family, but may have different functions.

Journal Article↗

PubMed2000

Long-term follow-up of unilateral pallidotomy in advanced Parkinson's disease.

BACKGROUND: Although the short-term benefits of posteroventral pallidotomy for patients with advanced Parkinson's disease have been well documented, little is known about the long-term outcome of the procedure. METHODS: We conducted a long-term follow-up study of a cohort of 40 patients who had undergone unilateral posteroventral medial pallidotomy between 1993 and 1996. Twenty patients were not evaluated because they had undergone a second surgical procedure (11 patients) or had died (2) or because they had dementia or another debilitating illness (4), lived too far away (1), or had been lost to follow-up (2). We conducted serial postoperative assessments of parkinsonism in the remaining 20 patients while they were taking medications ("on" period) and after overnight withdrawal of the drugs ("off" period). The mean follow-up time was 52 months (range, 41 to 64). RESULTS: The combined off-period score for activities of daily living and motor function on the Unified Parkinson's Disease Rating Scale was 18.0 percent better at the last evaluation than at base line (95 percent confidence interval, 4.9 to 31.0 percent; P=0.01). Significant improvements were also evident in the off-period scores for contralateral tremor (65.4 percent improvement, P=0.007), rigidity (43.2 percent, P=0.03), and bradykinesia (18.2 percent, P=0.04) and in the on-period score for contralateral dyskinesia (70.6 percent, P<0.001). Changes in medication did not contribute to the sustained improvement. The 20 patients who could not be included in the long-term analysis had similar base-line characteristics but a worse response to surgery at six months. CONCLUSIONS: In the group of patients with advanced Parkinson's disease who could be enrolled in our long-term follow-up study of unilateral posteroventral medial pallidotomy (20 patients from the original cohort of 40), significant early improvements in off-period contralateral signs of parkinsonism were sustained for up to five and a half years. There was a sustained significant improvement in on-period contralateral dyskinesia but not in other on-period signs of parkinsonism.

Activities of Daily Living↗

PubMed2000

Human umbilical cord blood effect on sod mice (amyotrophic lateral sclerosis).

In previous studies we observed that human umbilical cord blood (HUCB) could have a protective effect on the onset of disease and time of death in MRL Lpr/Lpr mice which have an autoimmune disease that may be considered similar to human lupus. We believed a temporary xenograph may have occurred in these animals with the disease process delayed and the life span markedly increased. When HUCB is stored at 4 degrees C in gas permeable bags, there is a decrease of the cell reaction in mixed lymphocyte cultures. The blood, however, maintains a significant number of cells capable of producing replatable colonies. This study attempted to determine the effect of HUCB on SOD1 mice (transgenic B6SJL-TgN(SOD1-G93A)1GUR), which have a mutation of the human transgene, (CuZn superoxide dismutase gene SOD1) that has been associated with amyotrophic lateral sclerosis. We previously developed evidence that the survival of lethally irradiated mice was related to the number of human mononuclear cells administered. In the present study, we decided to investigate the effect of a relatively large dose of human mononuclear cord blood cells on SOD1 mice subjected to a sublethal dose of irradiation preceded by antikiller sera (rabbit anti-asialo). The SOD1 mice show evidence of paralysis at 4 to 5 months. The average expected lifetime of these mice is reported to be 130 days (Jackson Laboratory). In this experiment, there were 23 mice. Two mice died before the onset of paralysis. The remainder were divided into three groups: group I: control group of 4 untreated mice; group II: an experimental group of 6 mice treated with antikiller sera, 800 cGy irradiation plus 5 x 10(6) congenic bone marrow mononuclear cells; group III: another experimental group of 11 mice treated with antikiller sera, 800 cGy irradiation plus 34.2-35.6 x 10(6) HUCB mononuclear cells, previously stored for 17-20 days at 4 degrees C in gas permeable bags. The results were as follows: the average age at death was: (I) 127 days for the untreated control group, (II) 138 days for the group that received 800 cGy of irradiation and congenic bone marrow (BM) and (III) 148 days for the group that received irradiation and HUCB. (P < 0.001 HUCB vs control, p < 0.01 HUCB vs BM). The longest surviving mouse in each group was 131, 153, and 182 days old respectively. In summary, large doses of HUCB mononuclear cells produced considerable delay in the onset of symptoms and death of SOD1 mice. These preliminary results may not only indicate that amyotrophic lateral sclerosis is an autoimmune disease, but may also indicate a possible treatment for a devastating disease and possibly others.

Adoptive Transfer↗