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Biomedical subjects

B Chen

Publications and source records attributed to B Chen.

At least 343 records · Page 19Linked to original sources
PubMed1997

[Differential display analysis of human fetal brain mRNAs and isolation of brain-specific novel ESTs].

Using the differential display technique (DDRT-PCR) originally developed by Liang and Pardee, we tried to isolate the stage-specific or tissue-specific genes in the developing human neural system (brain). With about fifty sets of arbitrary primers and anchored primers, DDRT-PCR was carried out to analyze the differentially expressed mRNAs between human fetal brains of different developmental stage or different parts of human fetal brain at the same developmental stage. About one hundred bands containing cDNA fragments of differential interest were cut out from the polyacrylamide gel, thirty-four of which were cloned and sequenced. They were accepted as novel cDNA sequences by GeneBank. In order to check the feasibility of DDRT-PCR, three of the thirty-four cDNA sequences were randomly chosen as probes for further analysis by dot blot RNA hybridization, and two proved to be specifically expressed in human brain.

Brain Chemistry↗
PubMed1997

[Long-term results in 31 patients on total hemispherectomy modified for infantile hemiplegic epilepsy].

To overcome long-term complications of hemispherectomy, We modified its operative method. The modified hemispherectomy was performed for 31 patients between 1985 and 1992. These patients were studied for 7 years after operation. The results showed total control of seizures in 28 children with chronic epilepsy (90%) or near-total control in the others. No deaths or delayed complications were noted but improvement in behavior and hemiplegia. CT and MRI showed marked shift of the remaining hemisphere. On brain-stem auditory evoked potentials, the latency of peak I was not variant (P > 0.05). The method makes the insulation of the subdural cavity from the ventricular system more reliable, and climates the pathological conditions.

Adolescent↗
PubMed1997

[LIM homeobox genes family in nervous system].

Homeobox genes define a class of genes containing homeobox sequences and encoding proteins, that are identified as transcription regulator controlling cellular development and differentiation, and controlling patterns of gene expression. LIM homeobox genes contain both a homeobox and a conservative sequences (encoded LIM domain). The members of the LIM homeobox genes family which have recently been identified include lin-11, mec-3, apterous(ap), isl-1, LH-2, Rlim, lim-1, lmx-1, Xlim-1 and Xlim-3. Recent findings suggested that products expressed by LIM homeobox genes family play an important role in adjusting differentiation and developmental of the organism. The effects of LIM homeobox genes in the differentiation and development of neurons are currently attracting more and more attention.

Animals↗
PubMed1997

High performance liquid chromatographic determination of dextromethorphan and its metabolite in human urine.

A reverse-phase high-performance liquid chromatographic method was established for the determination of dextromethorphan (DM) and its metabolite dextrophan (DX) in human urine. The sample was purified by an acid-base extraction followed by HPLC analysis on a phenyl column. The eluate was monitored by fluorescence at 280 nm (excitation) and 310 nm (emission). The limit of detection of DM was 0.023 mg.L-1. The within-day and between-day RSD% of DM and DX were all lower than 5%. The average recovery was 104.78%.

Chromatography, High Pressure Liquid↗
PubMed1997

[Isolation of coltivirus from mosquitoes in Beijing and it's biological characteristics].

Two strains (Beijing 95-70 and 95-75) of coltivirus were isolated from mosquitoes collected in Beijing during summer-autumn in 1994. The viruses caused cytopathogenic effect on C6/36 cells but not on BHK-21 and Vero cells, and were not lethal for new born mice and three week old mice. The isolates were resistant to 5'-IdU and ether, but sensitive to acid pH 3.0. There were 12 segments RNA shown by polyacrylamide gel electrophoresis (PAGE) and PAGE profile of the two isolates were similar (6-6). The PAGE profile was also similar to that of the TRT2 strain isolated in 1991, but there were at least 8 segments slightly different between the new isolates and TRT2 in band migration distance. Tissue culture cross-neutralization test showed that the new isolates were antigenically related to TRT2 strain identified as coltivirus. Growth curve of the two isolates on C6/36 cells showed that virus titer began to rise at the first day after infection and continued to increase up to 7.0 Log TCID50 per 0.1 ml and maintained a high level until the 21st day after infection. It seems that the virus may cause persistent infection on C6/36 cell.

Animals↗
PubMed1997

Oltipraz chemoprevention trial in Qidong, People's Republic of China: study design and clinical outcomes.

In 1995, 234 adults from Qidong, Jiangsu Province, People's Republic of China, where hepatocellular carcinoma is the leading cause of cancer deaths and exposure to dietary aflatoxins is widespread, were enrolled and followed in a Phase II chemoprevention trial. The goals of the study were to define a dose and schedule of oltipraz for reducing levels of validated aflatoxin biomarkers and to characterize dose-limiting toxicities. Healthy eligible individuals, including those infected with hepatitis B virus, were randomized to receive either 125 mg of oltipraz daily, 500 mg of oltipraz weekly, or placebo. Blood and urine specimens were collected to monitor toxicities and evaluate biomarkers over the 8-week intervention period and subsequent 8-week follow-up period. Unique trial aspects included a synchronous follow-up schedule, daily observed administration of all medications, timely international data transference, and use of biomarkers as outcomes. One hundred thirty-two participants took their medications without interruptions, approximately 77% contributed all nine urine samples, and 78% contributed all seven blood samples. Fifty-one participants (21.8%) reported clinical adverse events. An extremity syndrome, developing soon after the start of treatment, was the only event that occurred more frequently (P = 0.002) among the active groups (18.4 and 14.1% of the daily 125 and weekly 500 mg arms, respectively) compared with placebo (2.5%). The oltipraz arms did not differ in symptom type or severity, and there were no indications of exacerbated drug intolerance among the few participants infected with hepatitis B virus. The good compliance with an intense follow-up schedule shows that chemoprevention trials with biomarker end points may be conducted in such populations.

Adult↗
PubMed1997

[Record linkage of the elderly in the national surveys on the geriatric intermediate care facility].

Geriatric intermediate care facility, GICF, have been established since 1986 in Japan. The term of 'intermediate' denotes a facility midpoint between a hospital and home, with a powerful rehabilitation function. The annual governmental survey on GICF has been applied to all GICFs in Japan since 1989. This survey is a cross-sectional-type survey. For evaluating the role of GICF, we considered a type of cohort study using these surveys for four years by means of a record linkage method. This method is possible, because subjects of a survey for any year become subjects in the survey of the following year, if they have been in a GICF for more than one year. In this paper, for the purpose of preparing for a study of the role of GICF, we report some results about a record linkage for these surveys, and two continuing rates were calculated for these cohorts. Sources were personal records in 1989 to 1992 gathered by The National Survey on GICF in Japan. The record linkage method is as follows. We divided the annual personal records into several files by both the periods of the last admission and the survey year. Three cohorts, i.e. a cohort-89, a cohort-90 and a cohort-91 for persons for whom the first survey was 1989, 1990 and 1991, respectively are thus obtained. Next, we identified individuals from the annual files in each cohort. As personal names were not available, we identified individuals by sex, birth date, date of admission and facility number by the use of a personal computer and a FORTRAN program. Results were as follows. 1. Multiple matched persons were few (0.5% or less), and identification rates were 90% or more, despite the fact that basic linking variables were used. 2. Continuing rates were about 40% and decreased with new cohorts, while those of a fixed cohort were increased as length of stay increased. These reveal that recent admissions who stay continuously at a GICF were decreasing, but the longer the period for which the elderly stays at a GICF, the less possibility that he will be discharged. 3. Between record agreement rates for individuals over two years for unchangeable characteristics such as a place before admission which are expected to be 100% were about 80%. 4. A record linkage method appears to be useful for calculating continuing rates classified by any attribute.

Aged↗
PubMed1997

Oltipraz chemoprevention trial in Qidong, Jiangsu Province, People's Republic of China.

Oltipraz has been used clinically in many regions of the world as an antischistosomal agent and is an effective inhibitor of aflatoxin hepatocarcinogenesis in rats. This chemopreventive action of oltipraz results primarily from an altered balance in aflatoxin metabolic activation and detoxication. In 1995, a randomized, placebo-controlled, double-blind intervention was conducted in residents of Qidong, People's Republic of China, who are at high risk for exposure to aflatoxin and development of hepatocellular carcinoma. The major study objectives were to define a dose and schedule for oltipraz that would reduce levels of aflatoxin biomarkers in biofluids of the participants, and to further characterize dose-limiting side effects. Two hundred thirty-four healthy eligible individuals, including those infected with HBV, were randomized to receive either 125 mg oltipraz daily, 500 mg oltipraz weekly, or placebo. Blood and urine specimens were collected to monitor potential toxicities and evaluate biomarkers over the 8-week intervention and subsequent 8-week follow-up periods. Overall, compliance in the intervention was excellent; approximately 85% of the participants completed the study. Objective evaluation of adverse events was greatly facilitated by inclusion of a placebo arm in the study design. A syndrome involving numbness, tingling, and pain in the fingertips was the only event that occurred more frequently among the active groups (18 and 14% of the daily 125 mg and weekly 500 mg arms, respectively) compared to placebo (3%). These symptoms were reversible and could be relieved with non-steroidal antiinflammatory agents. A more complete understanding of the chemopreventive utility of oltipraz awaits completion of an assessment of the efficacy of oltipraz in modulating levels of aflatoxin biomarkers.

Animals↗
PubMed1997

Frequency distributions of plasma apolipoprotein(a) levels and phenotypes: a comparison between southern and northern Chinese populations.

OBJECTIVE: This study was designed to examine the genetic variation and levels of apolipoprotein (a) [apo(a)] in Chinese living in two different geographical regions of China and the influence of the apo(a) size polymorphism on plasma apo(a) levels. METHODS: An immunoradiometric assay was used to determine plasma apo(a) levels and a simplified and sensitive SDS-agarose gel electrophoresis method followed by immunoblotting with chemiluminescent detection for apo(a) phenotyping was employed to compare the frequency distributions of apo(a) levels and phenotypes in southern (Hong Kong) and northern (Henan) Chinese populations. RESULTS: Distributions of plasma apo(a) levels were highly skewed in both population groups. Although plasma apo(a) levels were generally higher in northern Chinese than in southern Chinese this was not explained by differences in K-IV repeats allele frequencies between these two population groups. The association of K-IV repeat length with apo(a) levels is similar in the two populations. CONCLUSIONS: We conclude that besides the apo(a) size polymorphism, which is similar in these two Chinese populations, other factors affect apo(a) levels to a certain degree. Most likely, this is the sequence variation in apo(a) gene which may not be the same in different Chinese populations.

Adult↗
PubMed1997

[Dobutamine technetium-99m-MIBI spect in evaluating the effects of coronary interventional management].

OBJECTIVE: To evaluate the effects of coronary interventional management by dobutamine 99mTc-MIBI single photon emission computed tomography (Dobu-ECT). METHODS: Dobu-ECT was performed in pre- and post-interventional management of 32 patients. Dobutamine was administered intravenously at incremental rates from 5 to 40 micrograms x kg-1.min-1 at 3-minute intervals. At the highest infusion rate, 20 mCi 99mTc-MIBI was injected intravenously, and tomographic imaging was performed after one hour. Rest imagings were taken after 24 hours with a second dose of 99mTc-MIBI. RESULTS: In 32 patients accepting interventional treatment, within 3-6 months follow-up, the results of Dobu-ECT showed a total effectiveness rate of treatment was 68.1%. 27 patients of whose Dobu-ECT showed significant reversible defects before procedure, the effectiveness rate was 77.8% (21/26), 6 still had reversible ischemia within the follow-up period, and restenoses of 5 patients were confirmed by angiography. We also compared the effect of percutaneous transluminal coronary angioplasty (PTCA) with intracoronary stenting using Dobu-ECT. The results showed that intracoronary stenting was more beneficial than PTCA (81.3% vs 43.8%, P < 0.05) CONCLUSION: Dobu-ECT can be used to evaluate the effect of interventional management and detect restenosis after procedure.

Adult↗
PubMed1997

[Experimental study on direct volume reconstruction].

Application of DVR is investigated with the X-ray equipment under single circle imaging geometry. A real volume model that consists of aluminum bar, lucite and air bar is designed. A prototype imaging system that includes X-ray cone-beams ource, rotating system, fluorescent screen, image intensifier, TV camera, image acquisitor and microcomputer is constructed. The experimental results show that DVR with the current simple X-ray equipment is of interests and values.

Image Processing, Computer-Assisted↗
PubMed1997

[Method and significance of removal of dermal epithelial components in the study of composite skin].

UNLABELLED: In order to investigate the possible re-epithelialization originated from the dermal epithelial components after trypsinization of the allo-dermis, microscopic observation, tissue culture study and histological observation after allo-grafting were adopted. The number of the hair follicles in dermal layer was counted in the study process. The results showed that a few of hair follicles in the structure of allo-dermis remained after trypsin digestion for 80 minutes. After culturing and grafting of such trypsinized dermis, none of the newly formed epithelium was observed. CONCLUSION: 1. Trypsinization of allo-dermis eliminates the antigenic epithelial components of dermis preventing the possibility of re-epithelization; 2. Strictly controled time is required while digesting the allo-dermis with trypsin.

Animals↗
PubMed1996

17 beta-Estradiol prevents dysfunction of canine coronary endothelium and myocardium and reperfusion arrhythmias after brief ischemia/reperfusion.

BACKGROUND: Brief myocardial ischemia is associated with myocardial and coronary endothelial dysfunction caused by oxygen free radicals released during reperfusion. Estrogen, known to have antioxidant activity, may prevent these complications. METHODS AND RESULTS: We assessed the effect of 2 weeks of treatment with 17 beta-estradiol (E, 100 micrograms.kg-1.d-1, n = 12) or placebo (P, n = 15) on myocardial and coronary endothelial function during the first 2 hours of reperfusion in dogs subjected to 15 minutes of ischemia induced by occlusion of the left anterior descending coronary artery (LAD). Our results show that the incidence of ventricular arrhythmias significantly decreased in E (3 of 12) compared with P (11 of 15). Systolic shortening, significantly depressed in P during early reperfusion, was maintained at preischemic levels in E. During reperfusion, the increase in LAD flow to acetylcholine, attenuated in P (60 +/- 6%), was preserved in E endothelium. (151 +/- 28%) and was associated with increased serum nitrite/nitrate concentration. n-Pentane in exhaled gas in vivo, an index of lipid peroxidation, increased significantly during early reperfusion in P (from 9.1 +/- 1.9 to 41.6 +/- 13.0 ppb, P < .05) but not in E (23.0 +/- 6.9 ppb). In vitro, arterial segments from E generated significantly less superoxide anion after hypoxia/reoxygenation than those from P. Ischemic/reperfused LAD segments from E also revealed a better preservation of endothelium-dependent relaxation in vitro (maximum relaxation, 42 +/- 4% versus 24 +/- 4% in P; P < .05). CONCLUSIONS: Estrogen protects against endothelial and myocardial dysfunction resulting from brief ischemia/reperfusion. This protection may relate to an antioxidant effect of estrogen.

Acetylcholine↗
PubMed1996

Primitive hematopoietic cells in murine bone marrow express the CD34 antigen.

The CD34 antigen is expressed on most, if not all, human hematopoietic stem cells (HSCs) and hematopoietic progenitor cells, and its use for the enrichment of HSCs with repopulating potential is well established. However, despite homology between human and murine CD34, its expression on subsets of primitive murine hematopoietic cells has not been examined in full detail. To address this issue, we used a novel monoclonal antibody against murine CD34 (RAM34) to fractionate bone marrow (BM) cells that were then assayed in vitro and in vivo with respect to differing functional properties. A total of 4% to 17% of murine BM cells expressed CD34 at intermediate to high levels, representing a marked improvement over the resolution obtained with previously described polyclonal anti-CD34 antibodies. Sixty percent of CD34+ BM cells lacked lineage (Lin) markers expressed on mature lymphoid or myeloid cells. Eighty-five percent of Sca-1+Thy-1(10)Lin-/10 cells that are highly enriched in HSCs expressed intermediate, but not high, levels of CD34 antigen. The remainder of these phenotypically defined stem cells were CD34-. In vitro colony-forming cells, day-8 and -12 spleen colony-forming units (CFU-S), primitive progenitors able to differentiate into B lymphocytes in vitro or into T lymphocytes in SCID mice, and stem cells with radioprotective and competitive long-term repopulating activity were all markedly enriched in the CD34+ fraction after single-parameter cell sorting. In contrast, CD34-BM cells were depleted of such activities at the cell doses tested and were capable of only short-term B-cell production in vitro. The results indicate that a significant proportion of murine HSCs and multilineage progenitor cells express detectable levels of CD34, and that the RAM34 monoclonal antibody is a useful tool to subset primitive murine hematopoietic cells. These findings should facilitate more direct comparisons of the biology of CD34+ murine and human stem and progenitor cells.

Animals↗
PubMed1996

Partially differentiated ex vivo expanded cells accelerate hematologic recovery in myeloablated mice transplanted with highly enriched long-term repopulating stem cells.

The ability of an infusion of ex vivo expanded hematopoietic cells to ameliorate cytopenia following transplantation of hematopoietic stem cells (HSCs) is controversial. To address this issue, we measured the recovery of circulating leukocytes, erythrocytes, and platelets in lethally irradiated mice transplanted with 10(3) enriched HSCs, with or without their expanded equivalent (EE) generated after 7 days of culture in interleukin-3 (IL-3), IL-6, granulocyte colony-stimulating factor and Steel Factor. Two HSC populations differing in their content of short-term repopulating progenitors were evaluated. Thy-1loLIN-Sca-1+ (TLS) bone marrow (BM) is enriched in colony-forming cells (CFCs), day 8 and day 12 spleen colony-forming units (CFU-S) (435 +/- 19, 170 +/- 30, and 740 +/- 70 per 10(3) cells, respectively), and stem cells with competitive long-term repopulating potential (> or = 1 per 43 cells). Thy-1loSca-1+H-2Khl cells (TSHFU) isolated from BM 1 day after treatment of donor mice with 5-fluorouracil (5-FU) are also highly enriched in competitive repopulating units (CRU, > or = 1 per 55 cells), but are depleted of CFCs, day 8 and day 12 CFU-S (171 +/- 8, 0 and 15 +/- 4 per 10(3) cells, respectively). Recipients of 10(3) TLS cells transiently recovered leukocytes to > or = 2,000/microL in 12 days, but sustained engraftment required 25 days. Platelets recovered to > or = 200,000/microL in 15 days, and erythrocytes never decreased below 50% of normal. Mice transplanted with 10(3) TSHFU cells recovered leukocytes in 15 days, and platelets and erythrocytes in 18 days. Recipients of unseparated normal or 5-FU-treated BM cells (containing 10(3) TLS or TSHFU cells) recovered safe levels of blood cells in 9 to 12 days, suggesting that unseparated marrow contains early engrafting cells that were depleted by sorting. Upon ex vivo expansion, total cells, CFCs and day 12 CFU-S were amplified 2,062-,83- and 13-fold, respectively, from TLS cells; and 1,279-, 259- and 708-fold, respectively, from TSHFU cells. Expanded cells could regenerate the majority of lymphocytes and granulocytes in primary (17 weeks) and secondary (26 weeks) hosts and were only moderately impaired compared to fresh HSCs. The EE of TSHFU cells was more potent than that of TLS cells, suggesting that more highly enriched HSCs are more desirable starting populations for this application. When mice were transplanted with 10(3) TSHFU cells and their EE, the duration of thrombocytopenia was shortened from 18 to 12 days, and anemia was abolished. Leukocytes were also elevated on days 9 to 12, although sustained recovery was not accelerated. Anemia was also abrogated in recipients of 10(3) TLS cells and their EE. Early platelet counts were slightly higher than with TLS cells alone, but leukocyte recovery was not improved. These data confirm that TLS cells contribute to early and sustained hematopoiesis, and demonstrate a benefit of ex vivo expanded cells in accelerating engraftment of more primitive TSHFU stem cells depleted of progenitors.

Animals↗
PubMed1996

Extensive alteration of fungal gene transcript accumulation and elevation of G-protein-regulated cAMP levels by a virulence-attenuating hypovirus.

Persistent infection of the chestnut blight fungus Cryphonectria parasitica with the prototypic hypovirus CHVI-713 results in attenuation of fungal virulence (hypo-virulence) and reduced accumulation of the GTP-binding (G) protein a subunit CPG-1. Transgenic cosuppression of CPG-1 accumulation in the absence of virus infection also confers hypovirulence. We now report the use of mRNA differential display to examine the extent to which virus infection alters fungal gene transcript accumulation and to assess the degree to which modification of CPG-1 signal transduction contributes to this alteration. More than 400 PCR products were identified that either increased (296 products) or decreased (127 products) in abundance as a result of virus infection. Significantly, 65% of these products exhibited similar changes as a result of CPG-1 cosuppression in the absence of virus infection. We also report that both virus infection and CPG-1 cosuppression elevate cAMP levels 3- to 5-fold. Additionally, it was possible to mimic the effect of virus infection and CPG-1 cosuppression on transcript accumulation for representative fungal genes by drug-induced elevation of cAMP levels. These results strengthen and extend previous indications that hypovirus infection causes a significant and persistent alteration of fungal gene expression/transcript accumulation. They further show that this alteration is primarily mediated through modification of the CPG-1 signaling pathway and suggest that, similar to mammalian Gi alpha subunits, CPG-1 functions as a negative modulator of adenylyl cyclase. Finally, these results suggest a role for G-protein-regulated cAMP accumulation in hypovirus-mediated alteration of fungal gene expression.

1-Methyl-3-isobutylxanthine↗
PubMed1996

Human G(alpha q): cDNA and tissue distribution.

G(alpha q), a member of the Gq family of heterotrimeric G proteins, transduces signals from several G protein-coupled receptors that stimulate membrane phosphoinositide hydrolysis. In order to further define the role of G(alpha q) in the function of G protein-coupled receptors, we have cloned the cDNA encoding human G(alpha q) from a prostate cDNA library. Human G(alpha q) exhibits high homology with its mouse homolog - 94% similarity at the nucleotide level, and 99% similarity at the amino acid level. Northern hybridization data indicate high expression of G(alpha q) mRNA in organs of the human reproductive system including ovary, prostate, and testis.

Amino Acid Sequence↗