Biomedical subjects

X Chen

Publications and source records attributed to X Chen.

At least 1,153 records · Page 64Linked to original sources

PubMed1997

[Determination of ampelopsin and myricetin in Ampelopsis cantoniensis].

Ampelopsis cantoniensis (Hook. et Arn.) Planch. is a Chinese herbal medicine rich in flavonoids. A method to determine flavonoids in the herbal was studied. After the herbal was extracted in hot water, Ampelopsin and myricetin in the extract were separated by polyamide column with eluent of ethanol-water and measured by spectrophotometry. As results, 100 g of the dry herbal contains 25.2 g of ampelopsin (RSD = 1.7%, recovery = 97.0%) and 1.77 g of myricetin (RSD = 3.3%, recovery = 103%).

Ampelopsis↗

PubMed1997

[Studies on the relationship between purified alpha class glutathione S-transferase (GST-alpha) and hepatocellular damage].

Using our ELISA kit for GST-alpha, we tested the serum GST-alpha levels of patients with hepatitis A, acute hepatitis B (HB), chronic active HB, chronic persistent HB and liver cirrhosis. Serum GST-alpha levels in all these groups of patients were significantly higher than those in the controls (P < 0.01). Serum GST-alpha levels was closely (P < 0.01) correlated with serum alanine transaminase (ALT) levels in various groups of patients except chronic persistant HB. The combined application of the two markers, GST-alpha and ALT, raised the sensitivity of detection for liver diseases. In detection of chronic persistent HB patients, the GST-alpha marker was more sensitive than ALT (P < 0.01). The follow-up data of GST-alpha and ALT markers in serum showed that the GST-alpha level could reflect the clinical progression of liver disease more exactly as observed in 79 liver cancer patients in then GST-alpha and ALT positive rate were 81% and 61% respectively (P < 0.01). In 30 persons with positive HBsAg, the positive rates of GST-alpha and ALT were 70% and 37%, respectively. These results indicated that, (1) the detection of GST-alpha combined with ALT was capable of increasing the sensitivity for recognizing hepatocellular damage; (2) the elevation of serum GST-alpha level mainly resulted from the increased expression of GST-alpha in liver cells during hepatocarcinogenesis, thus, the GST-alpha is thought to be a tumor marker for liver cancer; (3) GST-alpha measurement offers advantage over ALT for the detection of minor degree of hepatocellular damages. GST-alpha may act as an early, sensitive and specific enzyme marker.

Alanine Transaminase↗

PubMed1997

[Inhibitory effect of trisodium phosphonoformate (PFA) on duck hepatitis B virus (DHBV) DNA in vivo].

This paper described that DHBV infected ducklings were given with PFA 250 mg, 125 mg, 62.5 mg/kg b. i. d for 21 days intraperitioneally (i.p.) and dynamics of duck hepatitis B virus DNA (DHBV DNA) and duck hepatitis B surface antigen (DHBsAg) were detected in serum and distribution of DHBV DNA was tested in liver, kidney, pancreas and spleen. Supercoiled DNA (SC DNA) extracted from liver was analysed with Southern blot. The results showed that PFA in a dose of 125 mg and 250 mg/kg inhibited significantly the serum DHBsAg; doses of 125 mg and 250 mg/kg inhibited the serum DHBV DNA from 14 to 21 days, and dose of 250 mg/kg inhibited the serum DHBV DNA earlier even at 7 days after being given with PFA. Doses of 125 mg and 250 mg/kg inhibited obviously DHBV DNA in liver and kidney, but no inhibition was found in spleen and pancreas. The replication of DHBV DNA in liver of ducklings treated with PFA in a dose of 250 mg/kg for 21 days showed that the PFA inhibited significantly the synthesis of linear DNA (L DNA), relaxed circular DNA (RC DNA) and SC DNA. But DHBsAg and DHBV DNA in serum and DHBV DNA in liver, kidney, pancreas and spleen after treated with PFA for 21 days were still present, this meant that PFA treatment didn't clear off the virus genome in infected ducklings, the "rebounding" of DHBV appeared after cessation of the PFA treatment.

Animals↗

PubMed1997

[Determination of gamma-aminobutyric acid and glutamic acid in human cerebrospinal fluid by high performance liquid chromatography].

Gamma-aminobutyric acid (Gaba) and glutamic acid (Glu) are believed to be the major neurotransmitter. Levels in cerebrospinal fluid (CSF) may reflect their metabolism in various neurotic and psychiatric diseases. Measurements of Gaba and Glu in body fluids will help to elucidate their metabolic role and diagnostic value. In the present work, the concentrations of glutamic acid and gamma-aminobutyric acid in human cerebrospinal fluid were determined by reversed-phase high performance liquid chromatography using pre-column derivatized with dansyl chloride and UV detection at 254 nm. The mobile phase was A:CH3OH and B: THF/CH3OH/0.05 mol/L NaAc (pH 6.2) (5/75/420, V/V) with gradient elution. The flow rate was 1 mL/min. CSF samples were deproteinizated with methanol. After centrifugation at 15000 r/min for 10 min, the supernatant was introduced into a screw-capped vial and evaporated to near dryness at 80 degrees C. Derivatization was carried out by the addition of 250 microL of bicarbonate solution (pH 9.8) and 250 microL of dansyl chloride solution (4 g/L) followed by heating at 40 degrees C water bath for 30 min. Extraction was performed with 300 microL of ethyl acetate and the organic layer separated was dried at room temperature under nitrogen. The dry residue was dissolved and injected into the HPLC system. The linear range of the method was 5-1000 micromol/L (r = 0.9988) for Glu and 1-600 micromol/L (r = 0.9984) for Gaba. The lower limit of detection were 0.002 micromol/L and 0.001 micromol/L respectively. The recoveries were 96.9%-98.8% and 97.5%-98.8% and the coefficients of variation of peak height measurements were 2.2%-3.4% and 3.8%-5.6% respectivery. The method enables a simple, rapid and reproducible quantification of Glu and Gaba neurotransmitter.

Chromatography, High Pressure Liquid↗

PubMed1997

[Strain effects in Zn1-xMn(x)Se superlattices of II -VI diluted magnetic semiconductors].

We report the strain effects of Zn1-xMn(x)Se superlattices of II -VI diluted magnetic semiconductors by the photoluminescence measurements with compostions x = 0.2, 0.3, 0.4 in the temperature range T = 11K to 300K. The results show that the exciton energy tends to a red shift with the increasing of x due to the strain effects. The distribution of strain in wells and barriers presents a considerable change when their thickness ratio is altered. Photoluminescence spectra peaks as a function of temperature are mainly dominated by the band gap of ZnSe. The temperature coefficient of exciton energy is obtained.

English Abstract↗

PubMed1997

[Study on the interaction between CP and DNA].

In this paper, interaction between CP (Cis-ddp or ciplatin) and DNA (deoxyribonucleicacid) was studied using the fluorescence probe as well as the absorption spectra of DAN.

Absorption↗

PubMed1997

Expression of carbonic anhydrase isozyme III in the ciliary processes and lens.

PURPOSE: To determine whether carbonic anhydrase isozyme (CA) III is expressed in the ciliary processes and lens. METHODS: Total RNA was isolated from rabbit ciliary epithelium and human ciliary processes and from the anterior lens of rabbit, cow, and human eyes. First-strand cDNA was synthesized, and the polymerase chain reaction (PCR) was performed using oligomer primers designed to amplify CA III sequences specifically. Selected PCR products were eluted from agarose gels, cloned, and sequenced. Northern blots were performed to confirm the presence of CA III in these tissues. RESULTS: Polymerase chain reaction products of the predicted size were generated from rabbit ciliary epithelium and from rabbit, bovine, and human lens. The sequence of the PCR product from human lens was identical to the published sequence of the corresponding region of the human CA III gene. The sequence of the PCR products from rabbit ciliary epithelium and bovine lens showed 88% and 97% identity, respectively, with the corresponding sequences for human CA III, suggesting that the PCR products corresponded to the rabbit and bovine orthologs. Northern blots confirmed the presence of CA III mRNA in the rabbit ciliary epithelium and in rabbit and bovine lens. CONCLUSIONS: mRNA for CA III is present in the intraocular tissues of rabbits, cows, and humans. The previous detection of CA III protein in the bovine lens is confirmed, and it extended to the lenses of other species, including humans. The detection of mRNA for CA III in the ciliary epithelium is new and suggests that the ciliary epithelium contains not only isozymes II and IV but isoenzyme III as well. Although the function of CA III in the eye is unknown, it may play a role in fluid transport and homeostasis.

Animals↗

PubMed1997

CAND3: a ubiquitously expressed gene immediately adjacent and in opposite transcriptional orientation to the ATM gene at 11q23.1.

Using a magnetic beads-mediated cDNA selection procedure and a fetal brain expression library, we identified a transcriptional unit within a cosmid positive for the marker D11S384. Pursuit of its full-length cDNA led to the cloning of the third candidate gene (CAND3) we studied in our quest for the ataxia-telangiectasia (A-T) gene, ATM. CAND3 spans approximately 140 kb of genomic DNA and is located immediately centrimeric to ATM, with 544 bp of DNA separating the two genes. CAND3 encodes two ubiquitously expressed transcripts of approximately 5.8 kb and approximately 4.6 kb that are divergently transcribed from a promoter region common to ATM. Nucleotide sequence was determined for one of its alternately spliced transcripts. The predicted protein has 1175 amino acids and is novel in sequence, with only weak homologies to transcriptional factors, nucleoporin protein, and protein kinases, including members of the phosphatidylinositol 3-kinase (PI-3 kinase) family. Although neither homology to ATM nor any mutation of CAND3 in A-T patients has been found, the head-to-head arrangement of CAND3 and ATM, with expression of both housekeeping genes from a common stretch of 544 bp intergenic DNA, suggests a bi-directional promoter possibly for co-regulation of biologically related functions. YACs, BACs, cosmids, and STSs are defined to aid in further study of this gene.

Amino Acid Sequence↗

PubMed1997

Crystallization and preliminary studies of lima bean trypsin inhibitor.

Crystals of lima been trypsin inhibitor (LBTI) were obtained by using the vapor phase equilibration technique with sodium/potassium tartrate as the precipitating agent. The space group was determined to be cubic, I2(1)3 with a = 110.2. A These crystals diffract to about 1.9 A resolution. Preliminary analysis of self-rotation maps (calculated from native x-ray intensity data) suggests the presence of two monomers in the asymmetric unit. LBTI is very thermostable and retains activity even after boiling for 10 minutes. This property is exploited as part of its purification procedure.

Crystallography, X-Ray↗

PubMed1997

The consistency and concomitants of inhibition: some of the children, all of the time.

Toddlers displaying extremely inhibited behavior may be at risk for becoming socially withdrawn. However, behavioral inhibition may be a multifaceted characteristic, and its concurrent relation to toddler wariness with peers has not been examined. In this study, 108 toddlers (54 females) and their mothers were observed in novel situations involving unfamiliar settings, adults, and peers. Vagal tone, temperament, separation-reunion behavior, and maternal oversolicitousness also were assessed. There was little consistency of inhibited behavior across the 3 situations. Consistently inhibited toddlers had fearful temperaments, showed distress following maternal separation, and had mothers who were warm and controlling but unresponsive to children's cues during interaction. Toddlers with highly fearful temperaments and highly oversolicitous mothers were the most inhibited across contexts.

Child, Preschool↗

PubMed1997

Microsatellite marker development, mapping and applications in rice genetics and breeding.

Microsatellites are simple, tandemly repeated di- to tetra-nucleotide sequence motifs flanked by unique sequences. They are valuable as genetic markers because they are co-dominant, detect high levels of allelic diversity, and are easily and economically assayed by the polymerase chain reaction (PCR). Results from screening a rice genomic library suggest that there are an estimated 5700-10,000 microsatellites in rice, with the relative frequency of different repeats decreasing with increasing size of the motif. A map consisting of 120 microsatellite markers demonstrates that they are well distributed throughout the 12 chromosomes of rice. Five multiple copy primer sequences have been identified that could be mapped to independent chromosomal locations. The current level of genome coverage provided by these simple sequence length polymorphisms (SSLPs) in rice is sufficient to be useful for genotype identification, gene and quantitative trail locus (QTL) analysis, screening of large insert libraries, and marker-assisted selection in breeding. Studies of allelic diversity have documented up to 25 alleles at a single locus in cultivated rice germplasm and provide evidence that amplification in wild relatives of Oryza sativa is generally reliable. The availability of increasing numbers of mapped SSLP markers can be expected to complement existing RFLP and AFLP maps, increasing the power and resolution of genome analysis in rice.

Breeding↗

PubMed1997

Reduction by antiinflammatory drugs of the response of corneal sensory nerve fibers to chemical irritation.

PURPOSE: Nonsteroidal antiinflammatory drugs (NSAIDs) have been applied topically to reduce ocular pain caused by corneal injury or anterior segment surgery. The authors investigated whether the analgesic effects of the NSAIDs diclofenac, indomethacin, and flurbiprofen and of the calcium channel antagonist diltiazem on corneal pain are mediated by a reduction of nerve activity in corneal polymodal nociceptive fibers. METHODS: Impulse activity of single A-delta and C corneal nerve fibers was recorded from the ciliary nerves of anesthetized cats. Polymodal units were identified by their response to both touching with the Cochet-Bonnet esthesiometer and to acidic stimulation with 30-second pulses of 80% or 98.5% CO2 or 60 microl of 10 mM acetic acid, applied to the corneal receptive area. Ongoing impulse activity, firing responses to CO2 or acetic acid, and mechanical threshold of single fibers were recorded before and at various times (5 to 90 minutes) after topical application of 0.1% sodium diclofenac, 0.03% sodium flurbiprofen, 0.1% indomethacin, and 0.045% diltiazem hydrochloride or of their vehicles. RESULTS: Indomethacin, diclofenac, and flurbiprofen, in decreasing order of potency, gradually reduced the mean frequency of the impulse response of corneal polymodal nerve fibers evoked by CO2 stimuli. The progressive increase of ongoing activity, observed in vehicle-treated eyes after repeated CO2 stimulation was also prevented by NSAIDs. Diltiazem also attenuated the response to CO2 for a shorter period of time and with a faster time course. The mechanical threshold of corneal polymodal fibers was not affected by treatment with any of these drugs. CONCLUSIONS: Indomethacin, diclofenac, and flurbiprofen, as well as the calcium antagonist diltiazem, diminish the responsiveness of corneal polymodal nociceptors to chemical stimuli. This appears to be caused, in part, by a direct effect of these drugs on the excitability of polymodal nerve endings, but also by an inhibition by NSAIDs of the formation of cyclooxygenase products such as prostaglandins, thus reducing the enhanced responsiveness of nociceptors caused by local release of arachidonic acid metabolites from injured cells.

Acetic Acid↗

PubMed1997

Neuroendocrine cells in the prostatic carcinomas after neoadjuvant hormonal therapy.

Prostate cancer is a malignant tumor that is likely to increase in incidence in Japan. The most troublesome facet of this tumor is its conversion from a hormone-sensitive status to an insensitive one. Neuroendocrine differentiation may help explain this phenomenon. We studied the prevalence of neuroendocrine cells in prostate carcinoma after androgen ablation therapy. Radical prostatectomy specimens from 28 patients who had undergone neoadjuvant endocrine therapy with luteinizing hormone-releasing hormone analogue were retrospectively studied. Immunohistochemical staining was used to assess the localization of neuroendocrine cells. Neuroendocrine differentiation index, defined as the sum of the immunoreactivity scores of the specimens against anti-chromogranin A and anti-neuron specific enolase antibodies, was developed. Overall, 46.4% and 53.6% of the prostate carcinomas contained chromogranin A and neuron-specific enolase positive cells, respectively. Localization of these neuroendocrine cells in tumors was patchy. Two specific types of neuroendocrine cells were identified: a closed type and an open type based on the location of the neuroendocrine cells. The neuroendocrine differentiation index correlated with tumor grade, but not with tumor stage. The prevalence of neuroendocrine cells in higher grade prostatic carcinoma may help to explain the insensitivity of these cancers to hormonal therapy.

Adenocarcinoma↗

PubMed1997

[Cloning and expression of promoter and signal peptide function fragments from Lactococcus lactis in Escherichia coli].

Promoter and signal peptide function fragments from Lactococcus lactis were cloned in E. coli using a promoter-signal sequence probe vector pGPB14. Forty-two clones were obtained, whose level of resistance to ampicillin ranged from 100 to 8000 micrograms/ml. Eight clones were selected for beta-lactamase distribution assay. The beta-lactamase activity was found mainly in the periplasm, which indicated successful secretion of the enzyme. Southern hybridization test demonstrated that the inserted fragments were indeed from L. lactis. Restriction enzyme analysis revealed that the size of inserted fragments ranged from 80bp to 400 bp, four of which were sequenced on the vector pGEM-3Zf. It was found that the inserted fragments of pSEQ8 and pSEQ12 turned out to be part of the inserted fragments of pSEQ4 and pSEQ17 respectively. Promoter and translation initiation codon were found among all four fragments signal sequenced. One typical S. D. sequence and one atypical signal sequence were found in pHSB4 and pHSB8, while the other two contained no typical S. D. sequence and signal peptide sequence. In addition, it was found that the upstream regions of the promoter contributed to the efficiency of transcription initiation.

Base Sequence↗

PubMed1997

Association of angiotensin-converting enzyme gene insertion/deletion polymorphism with the clinico-pathological manifestations in immunoglobulin A nephropathy patients.

OBJECTIVE: To investigate the relationship between angiotensin-converting enzyme (ACE) gene insertion/deletion polymorphism and the clinico-pathological manifestations in patients with immunoglobulin nephropathy (IgAN). METHODS: A flanking primer pair and an insertion-specific primer pair were used to perform two polymerase chain reactions so as to analyse the insertion/deletion polymorphism of ACE gene. RESULTS: There was a significantly higher genotype frequency for DD genotype in IgAN patients. The frequencies for DD genotype were also higher in those patients with hypertension and/or heavy proteinuria and/or severe glomerular sclerosis (P < 0.05). CONCLUSIONS: We observed a significant association of the deletion polymorphism of ACE gene with renal insufficiency, hypertension and severe glomerular lesions at biopsy. The deletion allele may play a role, at least to some extent, in the deterioration and progression in IgA nephropathy.

Adolescent↗

PubMed1997

[Correction of occipito-posterior position by maternal posture during the process of labor].

OBJECTIVE: To investigate the effect on correction of occipito-posterior (OP) presentation by changing maternal posture during labor. METHOD: A prospective study was conducted in 120 pregnant women from March 1994 to December 1995. Women in labor were instructed to take the lateral posture so that the resultant force of the gravity of the fetus, the buoyancy of amniotic fluid, and the intermittent uterine contraction may change the fetal position from occipito-posterior into occipito-anterior (OA) presentation. Another 120 women were selected as controls. RESULTS: (1) In the study group, 106 women (88.3%) delivered vaginally with fetal presentation changed from OP into OA, and 14 (11.7%) received cesarean section. In the control group, only 20 women (16.7%) delivered vaginally, and 100 (83.3%) had cesarean sections (P < 0.001). (2) The average time interval in the study group was 302.6 min for the first stage and 59.8 min for the second stage, whereas 483.7 min and 156.1 min respectively in the controls. A significant difference was noted (P < 0.01). CONCLUSION: It is an effective method for the mother to take the lateral posture on the same side of the fetal spine for correcting the OP position. The incidence of dystocia may be reduced as well as the cesarean section rate. The method in simple and effective, and can be used in most of hospitals.

Adult↗

PubMed1997

[The expression of AT1A receptor and its modulation by benazepril in the renal tubulointerstitial lesions induced by ureteral obstruction].

OBJECTIVE: To study the expressions of angiotensin II 1A receptor (AT1A) both at the mRNA level and the protein level and their modulation by an angiotensin converting enzyme inhibitor, benazepril, in the renal tubulointerstitial injuries induced by unilateral ureteral obstruction (UUO) in rats. METHODS: Six SD rats (UUO-T) were administered benazepril in the drinking water (50mg/L). Additional 6 rats were used as untreated controls (UUO-C). Mean arterial Prossure (MAP) was measured at the 10th day after UUO, and then all animals were sacrificed. The expressions of AT1A were examined both at the mRNA level by in situ hybridization using a subtype-specific probe and at the protein level by an immunohistochemistry methods using AT1 receptor antibody in normal rat kidneys and the obstructed rat kidneys. RESULTS: MAP was 14.2 +/- 0. 6kPa in the UUO-T and 16.6 +/- 0.7kPa in the UUO-C (P < 0.05). Benazepril slowed the tubulointerstitial fibrosis (TIF) and reduced the expression of AT1A in the renal tubular epithelial cells, the interstitial areas, and the walls of renal arteriole in the UUO-T group. CONCLUSION: The increased expressions of AT1A were found in the acute renal tubulointerstitial pathogenesis induced by UUO. Benazepril may retard the progression of TIF and decrease the expression of AT1A in the obstructed kidneys. We conclude that the effects of Ang II on the obstructed kidneys may be due to its binding with AT1A.

Angiotensin-Converting Enzyme Inhibitors↗

PubMed1997

[Induction of apoptosis in human ovarian cancer cell line HO-8910 by transforming growth factor beta 1].

OBJECTIVE: To investigate the mechanism of inhibitory effects of Transforming Growth Factor beta 1 (TGF-beta 1) on human ovarian cancer cell in vitro. METHODS: The possibility of induction of apoptosis in human ovarian cancer cell line HO-8910 cells after treatment with TGF-beta 1 was studied by using methods of DNA electrophoresis, P1-staining, TdT-mediated dUTP-x nick end labeling and flow cytometer assay (FCM); and the kinetic change of expression of c-myc was also studied by relative quantified RT-PCR. RESULTS: DNA-strand nicks were present in cells after treatment with TGF-beta 1 at the final concentration of 20 ng/ml for 36 hours. The percent of labeled cells reached 75.55% on the time of 48 hours, PI staining-FCM assay also showed subdiploid peak of apoptotic cells at the same time. The typical apoptotic DNA ladder was present in genomic DNA preparation after treatment with TGF-beta 1 for 60 hours, meanwhile, the expression of c-myc in cells started to decrease beginning at treatment for 9 hours. CONCLUSIONS: TGF-beta 1 can induce apoptosis in HO-8910; such an inductive effect may occur mainly in G0/G1 phase. The effects of TGF-beta 1 on the inhibited expression of c-myc and on the enhancement of cAMP concentration may also play important roles in the process of apoptotic induction.

Apoptosis↗