Biomedical subjects

Y Yan

Publications and source records attributed to Y Yan.

At least 73 records · Page 4Linked to original sources

PubMed2001

Changes of evoked potentials and evaluation of mild hypothermia for treatment of severe brain injury.

OBJECTIVE: To observe the changes of evoked potentials after severe brain injury and the effect of mild hypothermia on acute severe brain injury. METHODS: A total of 44 patients with severe closed head injury (GCS 3-8, admitted within 10 hours from injury) admitted from May 1998 to March 1999 were selected for this study. All patients were admitted into the intensive care unit and divided into 2 groups, Group A (GCS 3-5) and Group B (GCS 6-8). Patients were also randomly assigned to either normothermia or hypothermia subgroups. Patients in the hypothermia group were cooled to 32-34 degrees C. Median nerve short-latency somatosensory evoked potentials (SLSEP) and brain stem auditory evoked potentials (BAEP) were recorded before cooling and 4, 24, 48, 72, 96 and 120 hours, respectively after cooling and temperature resuming. SLSEP and BAEP were measured at the same time in the normothermia group (control group). The changes of evoked potentials (EP) were analyzed by statistical methods. RESULTS: In the Group B, N(20) amplitudes in SLSEP and I/V amplitudes in BAEP after mild hypothermia treatment in the hypothermia group differed significantly from those in the control group (P<0.05). However, in the Group A, no significant difference in all parameters was found. CONCLUSIONS: These results demonstrate that mild hypothermia treatment (32-34 degrees C) in the Group B has a significant neuroelectrophysiological effect on severe brain injury. Nevertheless, the effect of mild hypothermia in the Group A is not apparent and needs further studying.

Acute Disease↗

PubMed2001

[Relationship between epidemiology of HIV-1 infection and HIV-1 subtypes in Fujian province].

OBJECTIVE: To explore the relationship of AIDS epidemic and HIV-1 subtype in Fujian province of China based on molecular findings. METHODS: HIV-1 infected persons and patient with AIDS (HIV/AIDS) were identified by AIDS surveillance project in the province. AIDS epidemic situation was estimated by related data collected from the HIV/AIDS cases. HIV-1 C2-V3 region amplified from the PBMC DNA of HIV/AIDS cases was analysed by nucleotide sequencing to identified HIV-1 subtype. RESULTS: One hundred and eighty-eight cases of HIV/AIDS were found from 1987 to the end of 2000. Among 59 AIDS cases, 53 had died. HIV infection through heterosexual contacts took up 65.4%, including 44.1% of them infected abroad. Out of them, 83.1% were infected in Southeast Asia. Thirty-nine point nine percentage of the total HIV(+) were infected in China, while 9.0% were infected through blood transmission. Sequence analysis from 41 specimens showed that there were 4 kinds of HIV-1 subtypes, including A, B, C and E. Subtype E took up 75.6% (31/41), all infected by heterosexual contacts; subtype B taking up 17.1% (7/41) with most of them infected through blood transmission; subtype A and C were seen only 1 and 2 cases respectively. Gene divergence of innergroup of subtypes E was 12.245% +/- 3.894%, while subtype B was 10.762% +/- 2.707%. The high divergence of subtype E could be attributed to the region and time of infection. CONCLUSION: HIV prevalent rate has been increasing in Fujian with major transmission route of heterosexual contact. The dominant strain of HIV-1 was subtype E.

Acquired Immunodeficiency Syndrome↗

PubMed2001

[Study on the epidemiology and factors influencing the behavior of school children in Taiyuan].

OBJECTIVE: To study the epidemiological features and factors influencing behavior problems of school children in Taiyuan. METHODS: One thousand five hundred and ninety-seven school children aged 6 - 11 years selected from three schools differently located in three city proper were measured by Achenbach Child Behavior Checklist. RESULTS: Pervaleuce rate of children having behavior problems averaged 12.34%, with 12.40% in boys and 12.27% in girls. If was found higher in Hexi than in other two schools. The total scores of CBCL hyperkinesia and discipline violation among boys were higher than that of girls. The score including depression, somatic problem, and social withdraw of girls was found higher than that of boys. The result of multiple regression indicated that factors as interest in study, easy rearing, and good living condition when mother was in pregnancy were possibly benefit to behavior development in children, while beating and scolding children, indifference toward children, and particular preference of diet seemed to be the main risk factors affecting children's behavior. CONCLUSION: There appeared different rates of childrens behavior problems among pupils. The scores of CBCL were different between boys and girls. It is essential to adopt comprehensive measures for the prevention of behavior problems in children.

Child↗

PubMed2001

[The antioxidative effect of procyanidins from pine bark in vitro].

OBJECTIVE: To assess the antioxidative effect of procyanidins from pine bark on free radical damage. METHODS: Hemolysis, Malonaldehyde(MDA) level of mice liver homogenates, the conformation changes of irradiated plasmid PUC18 were used as indexes. RESULTS: Procyanidins could reduce the hemolysis degree of human RBC induced by H2O2 significantly(P < 0.01), reduce the MDA level of mice liver homogenate initiated by VitC/Fe2+ remarkably(P < 0.01), and reduce the degree of single-strain break of plamid PUC18 induced by 60Co gamma significantly(P < 0.01). CONCLUSION: Procyanidins had good antioxidative function. It can prevent RBC membrane, plasmid DNA suffering from oxygen free radical damage in vitro.

Animals↗

PubMed2001

[Isolation of HIV-1 from infected individuals in Fujian Province].

OBJECTIVE: To isolate the virus from HIV-1 infected individuals. METHODS: Blood specimens were collected from 10 HIV-1 infected persons in Fujian Province. Peripheral blood mononuclear cells (PBMCs) were separated from the heparinized blood. Each sample was cocultured with fresh normal PBMCs to isolate HIV-1. Supernatant of the cocultures was tested by using HIV-1 P24 antigen Kit. RESULTS: Of the 10 specimens, 9 showed positive for the P24. 4 of 9 isolated infected MT4 cells, and cell syncytias could be seen. Three isolates showed transient infection of MT4, which probably belong to slow/low virus. Only one isolate could infect MT4 successively, which had been passed for 15 generations without significantly changed viral titer; it is believed to be a rapid/high replication virus. CONCLUSIONS: HIV-1 virus was successfully isolated.

HIV Infections↗

PubMed2001

[Clinical analysis of 17 cases rhabdomyosarcoma in ear nose and throat].

OBJECTIVE: To better understand the rhabdomyosarcoma in ear nose and throat and make correct diagnosis. METHOD: 17 patients with rhabdomyosarcoma in ear nose and throat were investigated. Diagnosis, treatment and prognosis were analyzed retrospectively. RESULT: Among 17 patients with rhabdomyosarcoma, three patients were in stage I, four patients were in stage II, eight patients were in stage III and two patients were in stage IV. It is the commonest in nose and predisposed to male. The clinic presentations were related to the size and location of tumor. Comprehensive therapy was need in most of patients. Poor prognosis was noted in this disease. CONCLUSION: This disease is easy to misdiagnose. Early diagnosis and comprehensive therapy will make contribution to better prognosis.

Adolescent↗

PubMed2001

[Studies on the chemical constituents of the herba of Cuscuta chinensis].

The chemical constituents of the herb of Cuscuta chinensis Lam. were investigated. Five compounds were isolated from petroleum ether and chloroform fraction. Their structures were identified as beta-sitosterol, d-sesamin, 9(R)-hydroxy-d-sesamin, d-pinoresinol and daucosterol by chemical and spectroscopical methods. All these compounds were isolated from the stem for the first time.

Chemical Fractionation↗

PubMed2001

[Effect of organic solvents on DNA conformation by fluorescent probe method].

In this paper, the conformation of calf thymus DNA(DNA) is investigated in some common solvents by spectrofluorimetry. The result of fluorescence spectra and scatchard plot indicate that the binding constant between DNA and ethidium bromide (EB) will decrease with the increasing concentration of ethanol, and the number of binding sites will increase. The change of binding constant elucidate that the interaction between DNA and EB will become poor, and the change of binding sites shows that the conformation of DNA has transformed from B-form to A-form. In the course of this change, the distance between both neighboring base plan will be decreased. When the EB molecule just fit into the interval, the fluorescence intensity will be maximum. When DNA shrink further, the EB molecules will be excluded from DNA, then the fluorescence intensity will decrease. Although the conformation of DNA will be changed in organic solvents, it will not denaturate or dehelix, because the absorption of DNA will not increase greatly with the increasing concentration of ethanol. The melting temperature of DNA decreases continually as the weight fraction of ethanol concentration is increased. It shows that the DNA will be more distabilized in ethanol, so it helps to explain some phenomena of life and physiology. Meanwhile, the results offer an opportunity to further study the interaction DNA and insoluble drugs.

Animals↗

PubMed2000

Crystal structure of Escherichia coli UDPMurNAc-tripeptide d-alanyl-d-alanine-adding enzyme (MurF) at 2.3 A resolution.

MurF is required to catalyze the final step in the synthesis of the cytoplasmic precursor of the bacterial cell wall peptidoglycan, rendering it an attractive target for antibacterial drug development. The crystal structure of the MurF apo-enzyme has been determined using the multiwavelength anomalous dispersion method and refined to 2.3 A resolution. It contains three consecutive open alpha/beta-sheet domains. In comparison with the complex crystal structures of MurD and its substrates, The topology of the N-terminal domain of MurF is unique, while its central and C-terminal domains exhibit similar mononucleotide and dinucleotide-binding folds, respectively. The apo-enzyme of MurF crystal structure reveals an open conformation with the three domains juxtaposed in a crescent-like arrangement creating a wide-open space where substrates are expected to bind. As such, catalysis is not feasible and significant domain closure is expected upon substrate binding.

Adenosine Triphosphate↗

PubMed2000

Cadmium-induced mRNA expression of Hsp32 is augmented in metallothionein-I and -II knock-out mice.

Cadmium is toxic and carcinogenic to humans and animals. The testis and lung are the target organs for cadmium carcinogenesis. Heat shock proteins (HSPs) as well as metallothionein (MT) and glutathione (GSH) play an important role in protection against its toxicity. HSP32, also known as heme oxygenase-1, is a 32-kDa protein induced by heme, heavy metals, oxidative stresses, and heat. We investigated expression of the Hsp32 gene of various organs (the liver, lung, heart, stomach, kidney, and testis) in transgenic mice deficient in the MT-I and -II genes (MT-KO) and in control mice (MT-W) after an injection of cadmium chloride (CdCl2). Survival of MT-W mice after a subcutaneously injection of CdCl2 was higher than that of MT-KO mice, while no significant difference was observed in the level of GSH in each organ between MT-W and MT-KO mice. Northern blot analysis showed that the MT-I mRNA was more extensively induced in the liver, kidney, and heart than other organs 6 h after an injection of CdCl2 (30 micromol/kg body wt, sc). There was little increase of the MT-I mRNA in the testis when induced by CdCl2. Expression of the Hsp32 gene in the liver and kidney in response to CdCl2 was more extensively augmented in MT-KO mice than in MT-W mice. In the lung and testis, there was little induction and no augmentation in expression of the Hsp32 gene induced by CdCl2 in both MT-W and MT-KO mice. In the stomach, there was little induction of the Hsp32 mRNA in MT-W mice, but was increased in MT-KO mice. Immunohistochemical staining revealed that the HSP32 protein was strongly expressed in the kidney and liver of MT-W mice 24 h after an injection of CdCl2 (20 micromol/kg body wt, sc), while the expression of HSP32 protein was not increased in the testis. In metabolically active organs such as the liver and kidney, expression of the Hsp32 gene as well as the MT-I gene was extensively induced by cadmium in MT-W mice, and more eminently induced in MT-KO mice. We suggest that organs of low stress response to cadmium such as the testis and lung may be vulnerable target sites for cadmium toxicity and carcinogenesis.

Animals↗

PubMed2000

Visual estimate of the percentage of carcinoma is an independent predictor of prostate carcinoma recurrence after radical prostatectomy.

BACKGROUND: The importance of tumor size measurements as predictors of disease recurrence after radical prostatectomy in patients with prostate carcinoma remains somewhat controversial, and many pathologists do not report these measurements routinely. The authors studied the correlation between the visual estimate of the percentage of carcinoma in prostatic tissue from radical prostatectomy specimens and prostate carcinoma recurrence rates in a series of 595 patients who underwent radical prostatectomy. METHODS: A total of 595 men with clinically localized prostate carcinoma were treated by the same surgeon (W.J.C.) from 1993 through 1997. The percentage of carcinoma in radical prostatectomy specimens from these patients was assessed microscopically through visual estimate. The authors used Kaplan-Meier product limit estimates, log-rank statistics, and the Cox proportional hazards model to evaluate the percentage of carcinoma in the pathologic specimens as predictors of recurrence free survival. RESULTS: Of the 595 patients, 46 (8%) had evidence of tumor recurrence. The mean percentage of carcinoma in the prostatectomy specimen was 11.3% in the group of patients who did not have disease recurrence and 23.8% in the group of patients who did experience disease recurrence. The percentage of carcinoma, preoperative prostate specific antigen levels, tumor differentiation (histologic Gleason grade), and pathologic stage all were significant predictors of disease recurrence according to the Kaplan-Meier method (all log-rank P values < 0.0001). Using the Cox proportional hazards model, controlling for all of these variables, only pathologic tumor stage, Gleason score, and percentage of carcinoma proved to be independent predictors of disease recurrence. In the final model, which included pathologic stage, Gleason score, and percentage of carcinoma, for each 5% increase in the percentage of carcinoma in the surgical specimen, there was an 11% incremental increase in the chance of tumor recurrence. CONCLUSIONS: The visual estimate of the percentage of carcinoma in prostatic tissue specimens from patients who undergo radical prostatectomy is a practical, simple, and inexpensive method that provides important prognostic information after radical prostatectomy.

Adult↗

PubMed2000

Molecular cloning and identification of full-length cDNA encoding high affinity Fc receptor for bovine IgG (Fc gamma RI).

The receptor I for the Fc region of immunoglobulin G (Fc gamma RI) is a member of the Ig superfamily with a high affinity, and it mediates antibody-dependent cellular cytotoxicity and immune complex clearance. In this study, a cDNA encoding the bovine Fc gamma RI was cloned. The full-length cDNA sequence is 1050 bp long with a short 5'- and long 3'-untranslated end regions, which codes for 349 amino acids and contains a signal peptide, an extracellular region with three Ig-like domains, and transmembrane and intracytoplasmic domains. Five potential N-linked glycosylation sites are recognized in this sequence. Compared with the sequences of human and mouse Fc gamma RI, the homologies of nucleotide sequences are 80 and 69% and homologies of deduced amino acid sequences are 66 and 55%, respectively. It is shown that the sequences of the monomeric IgG binding domain in these three species of Fc gamma RI are highly conserved.

Amino Acid Sequence↗

PubMed2000

Improved scheme of chelation ion chromatography with a mixed eluent for the simultaneous analysis of transition metals at microg l(-1) levels.

An improved scheme of chelation ion chromatography (CIC) system and a mixed eluent for the simultaneous determination of transition metals are described. A method based on the improved CIC system and the mixed eluent (PDCA/Na2C2O4/LiOH/NaCl) for the analysis of seven metals (Pb2+, Cu2+, Ni2+, Zn2+, Co2+, Cd2+ and Mn2+) at microg l(-1) levels in a single isocratic elution is developed. The optimize conditions which are different from references for analyte concentration and chromatographic separation are studied in detail. D418 chelation resin is used to further reduce values of the reagent blank. The above seven metals are measured at 565 nm using 2-[(5-Bromo-2-Pyridyl)-Azo]-5-Diethyl-AminoPhenol(5-Br-PADAP) as the post-column derivatizing reagent. Detection limits range from 0.3 to 12 microg l(-1) when 4 ml of sample is pre-concentrated. The results of real sample analysis are satisfactory.

Chelating Agents↗

PubMed2000

Investigation of possible involvement of several genes related to development of hepatocarcinogenesis in rats.

A comparative study on the possible involvement of several genes in the susceptibility of chemical carcinogenesis was carried out using carcinogen-resistant DRH rat and -sensitive Donryu and F344 rats. Previously, we observed that the induction of glutathione S-transferase placental form (GST-P) in the liver of Donryu rats by 3'-methyl-4-dimethylaminoazobenzene (3'-Me-DAB) was significantly greater than that of DRH rats. In the present study, we tentatively determined base sequences of the enhancer region including GPE-I and GPE-II (GST-P enhancers I and II) of GST-P genes of DRH, Donryu and F344 rats, but we did not observe any nucleotide polymorphism around these regions. Furthermore, the mRNA levels of silencer binding protein (NFA-1) for the GST-P promoter of rat liver were also similar in the DRH and Donryu rats. Since clonal expansion of putative preneoplastic GST-P-positive foci in the DRH rat liver was significantly suppressed during 3'-Me-DAB administration, we examined whether two opposite growth controlling factors, TGF-alpha and TGF-beta, may participate in such suppression of growth. It was supposed that mannose 6-phosphate/insulin-like growth factor 2 receptor (M6P/IGF2R), at least in part, activates TGF-beta preproprotein. However, we observed that the levels of M6P/IGF2R mRNA in the livers of DRH were not higher than those of Donryu rats after being fed 3'-Me-DAB for 8 weeks. Another important factor in the carcinogenesis is insulin-like growth factor II itself. Although liver tumors induced by 3'-Me-DAB in F344 had high levels of IGF-II mRNA, little IGF-II gene expression existed in normal adult livers of Donryu, F344 and DRH rats. High levels of IGF-II mRNA were detected similarly in the livers of neonates from all these three strains of rats. Finally, we detected a significant increase of AFP (alpha-fetoprotein) mRNA in the livers of Donryu rats around 6 to 8 weeks from the start of 3'-Me-DAB feeding, which is in parallel with detrimental effects of this carcinogen on these rats. A reduced induction of AFP mRNA was observed in DRH rats under the same conditions. Further study will be needed to explain the lower tumor susceptibility in the DRH rat.

Animals↗

PubMed2000

Genetic resistance to chemical carcinogen-induced preneoplastic hepatic lesions in DRH strain rats.

DRH strain rats were established by inbreeding a closed colony of Donryu rats continuously fed the chemical hepatocarcinogen 3'-methyl-4-dimethylaminoazobenzene for over 10 years. They are highly resistant to chemical induction of liver cancer and preneoplastic lesions. We studied the genetic basis of DRH resistance to preneoplastic lesions by analyzing 108 (F344 x DRH)F2 male rats fed 3'-methyl-4-dimethylaminoazobenzene for 7 weeks. Five parameters of preneoplastic liver lesions were selected for quantitative analysis: (a) number of glutathione S-transferase placental form-positive foci per unit area of liver section; (b) percentage area occupied by the foci; (c) average size of foci; (d) glutathione S-transferase placental form mRNA level; and (e) gamma-glutamyltranspeptidase mRNA level. Furthermore, O6-methylguanine DNA methyltransferase and mannose 6-phosphatase/insulin-like growth factor 2 receptor mRNA levels were quantified. Composite interval mapping analysis showed that there were two remarkably significant clusters of quantitative trait loci affecting preneoplastic liver lesions on chromosomes 1 and 4. These clusters were designated collectively as Drh1 and Drh2, respectively. The functions of the recessive DRH allele of Drh1 and the semidominant DRH allele of Drh2 were to suppress the phenotypes of precancerous lesions. Each cluster showed two to three subpeaks in linkage likelihood plots, suggesting the presence of several closely linked quantitative trait loci affecting preneoplastic lesions. Possible candidate genes at each locus will be discussed. Expression of O6-methylguanine DNA methyltransferase and mannose 6-phosphatase/insulin-like growth factor 2 receptor did not affect DRH resistance to hepatocarcinogenesis, although they were polymorphic between DRH and F344 rats.

Alleles↗

PubMed2000

Distances between DNA and ATP binding sites in the TyrR-DNA complex.

The Escherichia coli regulatory protein TyrR controls the expression of eight transcription units that encode proteins involved in the biosynthesis and transport of aromatic amino acids. It binds to DNA as a homodimer with a subunit molecular mass of 57 640 Da, each of which has a single site for the binding of ATP within a central structural domain. This paper reports distances between four sites on the DNA and the ATP binding site as determined by fluorescence resonance energy transfer. The DNA was a 30mer containing a centrally located binding site for TyrR. Replacement of a thymidine residue with an aminouridine residue at positions -9, -7, -3, and 2 of the palindromic oligonucleotide sequence enabled the placement of a single fluorescein group along the major groove of the DNA. The energy transfer acceptor was ATP labeled with a rhodamine group through positions 2' and 3' of the ribose, positions that are known to cause minimal interference with the binding of ATP to protein. The dissociation constant for the binding of rhodamine-ATP to TyrR was 300 nM as determined by steady-state fluorescence anisotropy titrations. The energy transfer efficiencies were determined by measuring the level of quenching of donor fluorescence on binding rhodamine-ATP to the TyrR-DNA complex. The experimental transfer efficiencies were compared to theoretical values calculated for a model of the DNA-TyrR complex in which the position of the ATP binding site was allowed to vary over the surface of the monomer unit. Theory was written to account for the transfer from one donor to two acceptors, one on each monomer unit of the TyrR dimer. The results indicate that the ATP binding site is about 40-45 A from the nearest point on the DNA and distant from the DNA helix-turn-helix binding domain. The effects of ATP binding of (i) increasing the TyrR binding affinity by a factor of 4-5 and (ii) permitting the binding of the tyrosine corepressor must therefore occur because of a significant allosteric change in the conformation of the protein.

Adenosine Triphosphate↗

PubMed2000

Quality-of-life outcomes for men with prostate carcinoma detected by screening.

BACKGROUND: There is limited information on outcomes of prostate carcinoma treatments given to screened patient populations for whom cancer is usually detected at an earlier stage. METHODS: The authors conducted a cross-sectional evaluation of quality-of-life outcomes for men with prostate carcinoma detected in screening studies at a university center. Of 2234 men diagnosed with prostate carcinoma between 1989 and 1997, 74% responded to the questionnaire. Primary management included radical prostatectomy (76%), radiotherapy (11%), observation (7%), hormonal therapy (4%), and cryoablation (2%). Main outcome measures included validated measurements of quality of life, urinary and sexual functioning, and bother (36-item RAND Health Survey, UCLA Prostate Cancer Index). RESULTS: After controlling for demographic factors, differences among treatment groups were found for all general quality-of-life outcomes, with increased impairment in men who underwent hormonal therapy (all P values <0.05). Urinary and sexual function and bother were also significantly related to treatment. However, among men followed for > or =12 months, only 9% reported a moderate or major problem with urinary control. Sexual functioning was a moderate or major problem following treatment for 58% treated with prostatectomy, 48% treated with radiotherapy, 64% treated with hormonal therapy, 45% treated with cryoablation, and 30% managed with observation. Approximately one-third of the men younger than 70 years who underwent radical prostatectomy maintained adequate sexual functioning posttreatment. CONCLUSIONS: Up to 6 years after diagnosis, the majority of men with prostate carcinoma detected by screening were bothered by their current sexual function, regardless of treatment. In contrast, most men were not bothered by their current urinary function.

Age Factors↗

PubMed2000

Helicobacter pylori induces formation of stress fibers and membrane ruffles in AGS cells by rac activation.

Helicobacter pylori induces signaling cascades leading to changes in cytoskeleton and an inflammatory response. Information on the morphological changes and cytoskeletal rearrangements induced by attachment of the bacterium is contradictory and signal transduction pathways are not well known. Since rho family of small GTPases is known to mediate cytoskeletal response to various extracellular stimuli, and is also involved in several other important signal transduction pathways, we have investigated the role of rac and cdc42 in H. pylori-induced cytoskeletal changes in cultured carcinoma AGS cells. AGS cells grown with serum expressed actin filaments in the form of short stress fibers and thin network at the edges, which were depolymerized by removal of serum. In serum-starved cells both type I and type II strains of H. pylori induced formation of actin filaments and lamellipodia-like structures. Microinjection of active rac induced similar changes, but injection of inactive rac prevented the effects of H. pylori, while active or inactive cdc42 did not have any significant effect. Cytoskeletal effects of H. pylori were inhibited by actinomycin D, but not completely by cycloheximide. These results indicate that rac activation is involved in signal transduction cascade leading to cytoskeletal reorganization induced by H. pylori and that gene activation and synthesis of new proteins is necessary in this process.

Actins↗