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Biomedical subjects

Lin Zhang

Publications and source records attributed to Lin Zhang.

At least 307 records · Page 17Linked to original sources
PubMed2003

[A study on the construction of allelic ladders for 4 short tandem repeat loci (D7S817, D10S1432, D10S1213 and D18S865) and their genetic polymorphism in two Chinese populations].

OBJECTIVE: To produce standard allelic ladders for four STR loci(D7S817, D10S1432, D10S1213 and D18S865) by recombined plasmids and use them in the research of genetic polymorphism. METHODS: After being amplified by PCR, different STR allelic fragments were isolated from the polyacryramide gel. The STR allelic fragments were eluted into distilled water and reamplified by PCR to obtain purified allelic fragments. Next, the purified allelic fragments were subcloned individually into the PUC plasmid vectors, and the size and structure of the inserts were confirmed by the analysis of their DNA sequences. Then we transfected the PUC plasmid vectors into E. coli DH5 alpha cells, worked on selective culture, and finally, mixed the alleles of the four STR loci respectively. RESULTS: The standard allelic ladders for four new loci (D7S817, D10S1432, D10S1213 and D18S865) were obtained, with which the genetic polymorphisms of four new loci in Chinese Hans and Dongxiang ethnic groups were studied. CONCLUSION: The standard STR allelic ladders acquired by this method are of high value in forensic practice, and they are applicable to the analysis of genetic polymorphism.

Alleles↗
PubMed2003

[DNA-based technique and species identification].

The species identification plays a key role in forensic analysis. Generally, three methods have been applied for this purpose, they are morphologic-based, serologic-based and DNA-based techniques. This review mainly discussed the DNA-based technique and evaluate it's value in species identification of forensic science.

Animals↗
PubMed2003

[Preauricular lateral maxillocervical fasciocutaneous flap].

OBJECTIVE: To investigate the design and blood supply type of the reverse narrow pedicle lateral maxillocervical fasciocutaneous flap. METHODS: The reverse narrow pedicle lateral maxillocervical fasciocutaneous flap with its pedicle locate in front of auricle was designed to repair the defect caused by removing the malignant tumor in aged patients. The largest size is about 10 cm x 6 cm, the width of pedicle ranged from 2.5-3.0 cm, 2-4 cm in length. RESULTS: The flaps were used in 4 patients, age from 57 to 83 years old and the flap was designed as lateral maxillocervical fasciocutaneous flap. The flap was survived well in all patients, donor site can be closed without strain, no tumor relapsed. CONCLUSION: The flap should be included to be a reverse axial flap and it should be designed from jaw edge to chin. The pedicle couldn't be too narrow, in this way, donor site can be closed directly, and less surgical operation time needed. The patients can accept synthesize treatment early, for example actinotheraphy. It is an ideal choice for repair the defect caused by removing the malignant tumor in aged patients.

Aged↗
PubMed2003

[Detection and identification of emergence of HBV YMDD motif mutation during lamivudine treatment by hybridization to an oligonucleotide array].

OBJECTIVE: Gene chip technology was set up to quickly and accurately detect and identify the HBV P gene YMDD motif mutation during the chronic hepatitis treated with lamivudine. METHODS: DNA microarrays were prepared by spotting fluorescence labeled probes of target genes onto specially lattice glass slides with robotics. The serum samples from 30 patients with hepatitis B after 68-week treatment with lamivudine were detected double-blind by gene chips and by nucleotide sequences assay technique to identify the rate of emergence of HBV P gene YMDD motif mutation. RESULTS: Twenty-one patients were found HBV P gene YMDD motif mutation by the gene chips including 11 cases with YVDD and 10 cases with YIDD motif mutation. By direct sequencing of the PCR products, 11 cases were found to have YVDD with adenine741 changed into cytidine resulted in methionine552 changed into valine in which 6 cases with adenine669 changed into cytidine and leucine changed into methionine, 10 cases had YIDD motif mutation with guanosine743 altered thymidine methionine552 changed into isoleucine, including 3 cases with thymidine281 changed into cytidine and leucine565 altered proline. CONCLUSION: The gene chip can be used to test HBV YVDD,YIDD motif mutation compared with nucleotide sequences assay technique, the accuracy rate was 100%.

Antiviral Agents↗
PubMed2003

[The lipid peroxidation mechanism initiated by ischemia-reperfusion injury during renal transplantation].

OBJECTIVE: To explore the mechanism of acute ischemia-reperfusion injury (IRI) to renal-transplant METHODS: A total of 12 Chinese Sichuan White Pigs (SWPs) (2-3 months old, 17.5 +/- 4.6 kg, with clear family background) were used. 3 pairs of them with better tissue typing were subjected to renal allotransplantation. The other SWPs were allocated to renal autotransplantation. We assessed the SWPs' kidney function, serum superoxide dismutase (SOD) and malonaldehyde (MDA) after transplantation so as to shed light on the possible mechanism of IRI and to find out good detecting methods which could monitor IRI. RESULTS: Serum creatinine and urea increased in 2 days of postoperation and then returned to normal in both groups except the pigs that suffered from acute tubular necrosis or acute rejection. The concentrations of serum MDA and SOD began to increase 2 days after operation (P < 0.05). More increase of serum MDA and less increase of SOD were detected in renal allotransplant groups than in renal autotransplant groups (P < 0.05). The concentration of serum SOD and MDA were correlated (r = 0.961). CONCLUSION: IRI could initiate lipid peroxidation. IRI could be a single factor or be synergistic with immunologic factors to injure the transplanted organs.

Animals↗
PubMed2003

[Associations between aldosterone synthase gene polymorphisms and left ventricular structure and function in Chinese normal Han People].

OBJECTIVE: The aim of the present study was to investigate the association between a polymorphism of the aldosterone synthase gene CYP11B2 and left ventricular structure and function in Chinese Han people. METHODS: One handred and ten persons aged 20 to 49 years were studies by echocardiography to assess left ventricular size, mass and function. The subjects were genotyped with the use of PCR-RFLP. RESULTS: Three genotypes for aldosterone synthase at position -334 in the transcriptional regulatory region were found: TT, TC and CC. The distribution of sex and arterial blood pressure was homogeneous in the aldosterone synthase genotype groups. No significant associations of echocardiographic LV dimensions, mass and function with a specific aldosterone synthase genotype were noted. CONCLUSION: The above data are not in favor of a significant association between the polymorphisms of aldosterone synthase gene CYP11B2 and the LV structure and function in Chinese normal Han people.

Adult↗
PubMed2002

Development and in-vitro evaluation of sustained release poloxamer 407 (P407) gel formulations of ceftiofur.

The objective of this study was to develop sustained release Poloxamer 407 (P407) gel formulations of ceftiofur for treating foot infections in cattle. The formulations contained 25-35% (w/v) P407 alone or with polyvinyl pyrrolidone (PVP), carboxy methylcellulose (CMC), or hydroxylpropyl methylcellulose (HPMC) as an additive. The in-vitro release profiles of ceftiofur from the P407 formulations and the gel dissolution profiles were obtained simultaneously. Ceftiofur release followed zero order kinetics and correlated well with the weight percentage of P407 dissolved, indicating that the overall rate of release of ceftiofur is controlled by dissolution of the P407. An increase in P407 content from 25 to 35% resulted in a decrease in the rate of ceftiofur release. However, it appears that other factors may have also affected the drug release rate. Inclusion of PVP, CMC, and HPMC in the gel decreased the rate of release of ceftiofur to some extent. A decrease in the temperatures of the release medium decreased the release rate of ceftiofur, but not the rate of gel dissolution. The pH of the release medium showed a very slight effect on the release of ceftiofur and did not affect gel dissolution due to the non-ionic nature of P407.

Cephalosporins↗
PubMed2002

Quantitation of yeast ceramides using high-performance liquid chromatography-evaporative light-scattering detection.

A high-performance liquid chromatograph equipped with an evaporative light scattering detector (ELSD) (HPLC-ELSD) was used to assay the ceramides in yeast cells. The HPLC-ELSD method employed a cyanopropyl bonded column (CN column) that effectively separated the main interfering substance ergosterol without any derivatization process; most other interfering substances were also removed. The method can be applied for routine assay of ceramide content in yeast.

Ceramides↗
PubMed2002

[Genotyping of hepatitis C virus by hepatitis gene diagnosis microarray].

OBJECTIVE: To study the preparation of hepatitis C virus (HCV) diagnosis microarray and its accuracy in diagnosis of gene type of hepatitis C virus. METHODS: Probe and primer and primers were designed in 5'-untranslated region and C region of hepatitis C virus gene. The probes were synthesized by DNA synthesizer. Solutions of probe of the final concentration of 50 micromol/L were made by dissolving the probes into sodium carbonate buffer. Hepatitis C virus genotype array spotting was performed by pin-based spotting robot PixSys5500 with CMP3 pin. The gene chips were prepared by spotting the probes onto the specially treated glass sliders. Sixty HCV RNA positive serum samples were obtained from the in-patients of the Nanjing Second Hospital (experimental group), and 60 HCV RNA negative serum samples were obtained from the healthy people undergoing physical examination (control group). Quantitative examination of serum HCV RNA was made by fluorescent quantitation PCR. The HCV RNA in the serum specimens of the experimental group (with the HCV RNA concentration of more than 500 copies/ml) and of the control group (with the HCV RNA concentration of less than 500 copies/ml) was isolated and purified, underwent reversed transcription and nested PCR to be amplified, and then genotyped by gene microarray and HCV RNA sequencing. During the experiment, double blind method was used. RESULTS: Tested by the gene microarray, the serum specimens in the experimental group were all HCV RNA positive, out of which 46 cases were 1b type, 3 cases were 3a type, 3 cases were 3b type, 2 cases were 2a type, 2 cases were 2b type, 2 cases were 1b + 2a type, and 2 cases were 3a type. Tested by nucleotide sequencing assay, 50 cases were 1b type, 3 cases were 3a type, 3 cases were 3b type, 2 cases were 2a type, and 2 cases were 2b type. The double-blind test results showed a coincidence rate of 93.3% in genotyping HCV by these two methods. CONCLUSION: Hepatitis gene microarray can be used in detection of serum HCV RNA and in diagnostic genotyping with great accuracy.

Genotype↗
PubMed2002

Isoform-dependent formation of heteromeric Ca2+ release channels (ryanodine receptors).

Three ryanodine receptor (RyR) isoforms, RyR1, RyR2, and RyR3, are expressed in mammalian tissues. It is unclear whether RyR isoforms are capable of forming heteromeric channels. To investigate their ability to form heteromeric channels, we co-expressed different RyR isoforms in HEK293 cells and examined their interactions biochemically and functionally. Immunoprecipitation studies revealed that RyR2 is able to interact physically with RyR3 and RyR1 in HEK293 cells and that RyR1 does not interact with RyR3. Co-expression of a ryanodine binding deficient mutant of RyR2, RyR2 (I4827T), with RyR3 (wt) restored [(3)H]ryanodine binding to the mutant. Interactions between RyR isoforms were further assessed by complementation analysis using mutants RyR2 (I4827T), RyR2 (E3987A), RyR3 (I4732T), RyR3 (E3885A), and RyR1 (E4032A), all of which are deficient in caffeine response. Caffeine-induced Ca(2+) release was restored in HEK293 cells co-transfected with mutants RyR2 (I4827T) and RyR3 (E3885A), RyR2 (E3987A) and RyR3 (I4732T), or RyR2 (I4827T) and RyR1 (E4032A), but not with RyR1 (E4032A) and RyR3 (I4732T), indicating that mutants of RyR2 and RyR3, or RyR2 and RyR1, but not RyR1 and RyR3, are able to complement each other. Co-expression of RyR3 (wt) and a pore mutant of RyR2, RyR2 (G4824A), produced regulatable single channels with intermediate unitary conductances. These observations demonstrate that RyR2 is capable of forming functional heteromeric channels with RyR3 and RyR1, whereas RyR1 is incapable of forming heteromeric channels with RyR3.

Caffeine↗
PubMed2002

Calibration standardization algorithm for partial least-squares regression: application to the determination of physiological levels of glucose by near-infrared spectroscopy.

Calibration standardization methodology for near-infrared (near-IR) spectroscopy is described for updating a partial least-squares calibration model to take into account changes in instrumental response. The guided model reoptimization (GMR) algorithm uses a transfer set of eight samples to characterize the new response and a database of previously acquired spectra used to develop the original calibration model. The samples in the transfer set need not have been measured under the old instrumental conditions, making the algorithm compatible with samples that change over time. The spectra comprising the transfer set are used to guide an iterative optimization procedure that (1) finds an optimal subset of samples from the original database to use in computing the updated model and (2) finds an optimal set of weights to apply to the spectral resolution elements in order to minimize the effects of instrumental changes on the computed model. The optimization relies on an alternating grid search and stepwise addition/deletion steps. The algorithm is evaluated through the use of combination region near-IR spectra to determine physiological levels of glucose in a synthetic biological matrix containing bovine serum albumin and triacetin in phosphate buffer. The ability to update a calibration to account for changes in the response of a Fourier transform spectrometer over four to six years is examined in this study. Separate spectral databases collected in 1994 and 1996 are used with a transfer set and separate test set of spectra collected in 2000. With the 1994 database, the standardization algorithm achieves a standard error of prediction (SEP) of 0.69 mM for the 2000 test set. This compares favorably to SEP values > 2 mM when the original 1994 calibration model is used without standardization. A similar improvement in the prediction performance of the 2000 test set is obtained after standardization with the 1996 database (SEP = 0.70 mM).

Algorithms↗
PubMed2002

Enhanced basal activity of a cardiac Ca2+ release channel (ryanodine receptor) mutant associated with ventricular tachycardia and sudden death.

Mutations in the human cardiac Ca2+ release channel (ryanodine receptor, RyR2) gene have recently been shown to cause effort-induced ventricular arrhythmias. However, the consequences of these disease-causing mutations in RyR2 channel function are unknown. In the present study, we characterized the properties of mutation R4496C of mouse RyR2, which is equivalent to a disease-causing human RyR2 mutation R4497C, by heterologous expression of the mutant in HEK293 cells. [3H]ryanodine binding studies revealed that the R4496C mutation resulted in an increase in RyR2 channel activity in particular at low Ca2+ concentrations. This increased basal channel activity remained sensitive to modulation by caffeine, ATP, Mg2+, and ruthenium red. In addition, the R4496C mutation enhanced the sensitivity of RyR2 to activation by Ca2+ and by caffeine. Single-channel analysis showed that single R4496C mutant channels exhibited considerable channel openings at low Ca2+ concentrations. HEK293 cells transfected with mutant R4496C displayed spontaneous Ca2+ oscillations more frequently than cells transfected with wild-type RyR2. Substitution of a negatively charged glutamate for the positively charged R4496 (R4496E) further enhanced the basal channel activity, whereas replacement of R4496 by a positively charged lysine (R4496K) had no significant effect on the basal activity. These observations indicate that the charge and polarity at residue 4496 plays an essential role in RyR2 channel gating. Enhanced basal activity of RyR2 may underlie an arrhythmogenic mechanism for effort-induced ventricular tachycardia.

Animals↗
PubMed2002

[The "Fas counterattack": a mechanism for immune evasion in human hilar cholangiocarcinomas].

OBJECTIVE: To investigate FasL expression in hilar cholangiocarcinoma tissues and cultured cholangiocarcinoma cells, and to assess the its ability to induce apoptosis. METHODS: The expression of FasL in 48 specimens of human hilar cholangiocacinoma resected in operation and cultured QBC939 cholangiocarcinoma cell line was detected by RT-PCR, immunohistochemistry, and Western blotting. TUNEL and flow cytometry were used to detect apoptotic cells. RESULTS: Prevalent expression of FasL was detected in 48 resected hilar cholangiocarcinomas examined. TUNEL staining disclosed a high level of cell death among lymphocytes infiltrating FasL positive areas of tumor. FasL mRNA and protein was expressed in cholangiocarcinoma cells. Apoptosis was seen in 60% of Jurkat cells cultured together with QBC939 Cholangiocarcinoma cells. CONCLUSION: The hilar cholangiocarcinoma eludes immunological surveillance by inducing, via the Fas/FasL system, the apoptosis of activated lymphocytes.

Apoptosis↗
PubMed2002

Different effects of glucose starvation on expression and stability of VEGF mRNA isoforms in murine ovarian cancer cells.

Vascular endothelial growth factor (VEGF) has been implicated as a potent regulator of angiogenesis in tumors, and its protein exists as at least five isoforms with distinct biologic activities and clinical significance. Tumors under metabolic stress conditions dramatically increase VEGF expression due to both increased transcription and decreased mRNA degradation. However, it is not known how stress conditions regulate expression of each VEGF isoform. Here, we report a novel Taqman real-time RT-PCR strategy for quantification of all murine VEGF isoforms and find that (1) glucose starvation dramatically up-regulates the mRNA level of all VEGF isoforms, with the three abundant isoforms, VEGF120, VEGF164, and VEGF188, increasing at a similar rate, while the rare isoform VEGF144 is more markedly up-regulated; (2) glucose starvation induces a significant increase of the relative abundance of VEGF144 mRNA, but not the more prevalent isoforms VEGF120, VEGF164, and VEGF188, compared to total VEGF; and (3) the stability of each isoform mRNA differs under the control conditions as well as glucose starvation. The latter significantly stabilizes mRNA of all VEGF isoforms at a different rate, with VEGF144 most significantly stabilized. Our results indicate that under metabolic stress conditions VEGF144 is the most dramatically up-regulated VEGF isoform, probably through mechanism(s) different from the three abundant VEGF isoforms.

Alternative Splicing↗
PubMed2002

Effects of hyperoxia on human sensorimotor cortex activity produced by electrical stimulation of the median nerve: a functional magnetic resonance imaging study.

This study investigated the effect of hyperoxia on sensorimotorcortical activity resulting from electrical stimulation of the median nerve, using functional magnetic resonance imaging (fMRI). Nine volunteers underwent stimulation at 5 and 100 Hz while breathing 21% FIO(2) (fraction of inspired oxygen) or 100% FIO(2). fMRI data were correlated with a stimulus predictor curve, transformed into Talairach space and averaged by group. Normoxic (21% FIO(2)) and hyperoxic (100% FIO(2)) sensorimotor activation volumes were compared using Student's t-test. There were no significant differences between the primary somatosensory/primary motor/Brodmann area 40 (SI/MI/Ba40) and secondary somatosensory cortex (SII) activation volumes for normoxia and hyperoxia. (P>0.05). There was no difference between SI/MI/Ba40 and SII activations at 5 and 100 Hz. In contrast to results previously reported for primary visual cortex (V1), hyperoxia did not enhance sensorimotor cortical activation in area SI/MI/Ba40 or SII. These results indicate that there is regional heterogeneity of the fMRI response to hyperoxia in the cerebral cortex.

Adult↗
PubMed2002

Development of a precolumn derivatization method for the determination of free amines in wastewater by high-performance liquid chromatography via fluorescent detection with 9-(2-hydroxyethyl)acridone.

A simple, sensitive, and mild method for the determination of amino compounds based on a condensation reaction with fluorescence detection has been developed. 9-(2-Hydroxyethyl)acridone reacts with coupling agent N,N'-carbonyldiimidazole at ambient temperature to form activated amide intermediate 9-(2-acridone)oxyethylcarbonylimidazole (AOCD). The amide intermediate (AOCD) preferably reacts with amino compounds under mild reactions in the presence of 4-(dimethylamino)pyridine (base catalyst) in acetonitrile to give the corresponding sensitively fluorescent derivatives with an excitation maximum at lambda(ex) 404 nm and an emission maximum at lambda(em) 440 nm. The labeled derivatives exhibit high stability under reversed-phase conditions. The fluorescence intensities of derivatives in various solvents or at different temperatures were investigated. The method, in conjunction with a gradient elution, offers a baseline resolution of the common amine derivatives on a reversed-phase C18 column. The LC separation for the derivatized amines shows good reproducibility with acetonitrile-water including 2.5% DMF as mobile phase. The relative standard deviations (n = 6) for each amine derivative are <4.5%. The detection limits (at a signal-to-noise ratio of 3) per injection were 0.16-12.8 ng/mL. Further research for the field of application, based on the AOCD amide intermediate as derivatization reagent, for the determination of free amines in real water samples is achieved.

Acridines↗
PubMed2002

Apolipoprotein E affects the central nervous system response to injury and the development of cerebral edema.

Apolipoprotein E has been implicated in modifying neurological outcome after traumatic brain injury, although the mechanisms by which this occurs remain poorly defined. To investigate the role of endogenous apolipoprotein E following acute brain injury, noninvasive magnetic resonance imaging was performed on anesthetized mice following closed head injury. Effacement of the lateral ventricle was used as a radiographic surrogate for cerebral edema. At 24 hours following injury, apolipoprotein E-deficient animals had a greater degree of cerebral edema as compared to matched controls. In addition, the brains of apolipoprotein E-deficient animals had a significantly greater upregulation of tissue necrosis factor alpha messenger ribonucleic acid as compared to controls as early as 1-hr post injury. Thus, modulation of the endogenous central nervous system inflammatory response may be one mechanism by which apolipoprotein E affects outcome following acute brain injury.

Acute Disease↗