Biomedical subjects

X Xu

Publications and source records attributed to X Xu.

At least 613 records · Page 34Linked to original sources

PubMed1998

[Immunohistochemical research on brain stem injury: expression of heat shock protein 70 in rat brain after traumatic brain stem injury].

The aim of this study was to determine the expression of heat shock protein 70 (HSP70) as molecular chaperones, following traumatic brain stem injury(TBSI). The expression of HSP70 was detected in respective brain regions of rats 1 h, 3 h, 6 h, 12 h, 24 h after brain stem stabbing wound. Numerous HSP70 immunoreactivity positive blood vessel endothelioid and glia cells were found in cerebral, cerebellar cortex and hippocampus after 1 h, with H.E stain unchanged. In the area near the focal of brain stem injury, HSP70 immunoreactivity positive neurons increased significantly after 1 h of injury, reaching the highest level after 3 h, much higher than in other areas. HSP70 immunoreactivity positive cells still existed after 24 h of injury. It was suggested that TBSI cause the defectiveness of protein structure in brain, and induce HSP70 proteolysis of denature protein including misfolding or aggregate. TBSI can be diagnosed regionally by the increasing of HSP70 immunoreactivity positive neurons in the focal of brain stems.

Animals↗

PubMed1998

[Determination of diterpenoic acid, triterpenoids and tritersaponins in Aralia by RP-HPLC].

In this paper, an accurate RP-HPLC method for the determination of oleanolic acid 28-O-beta-D-glucopyranoside (I), oleanolic acid 3-O-alpha-L-arabinopyranoside (II), 3 beta-hydroxy-oleana-11, 13(18)-dien-28-oic acid (III), (ent)-pimara-8(14), 15-dien-19-oic acid (IV), oleanolic acid (V) and 3-ox-oleana-12-en-28-oic acid (VI) in 11 species of Aralia Linn. was described. The analytical column used was Supelco SIL-LC-18. The mobile phase was MeOH-1%HOAc-THF (500:110:1, pH 3.4). The flow rate was 1.2 ml.min-1. The detection wavelength was 205 nm. The linear ranges of I-VI were 0.135-2.160, 0.163-2.610, 0.123-1.962, 0.068-1.080, 0.135-2.160 and 0.248-2.646 micrograms, respectively. The recoveries of I-VI were from 86.88% to 93.31%. Detailed comparison of the diterpenoic acid, triterpenoids and tritersaponins for the group of herbal with those of woody the content of diterpenoic acid in herbal is higher than that of in woody. It showed that the diterponic acid is the specific constituent in the group of herbal, which is the difference to woody. This conclusion provides the evidence of the chemical classification for dividing the groups of herbal and woody into two distinct subgenus.

Aralia↗

PubMed1998

[Synthesis and anti-Candida albicans properties of L-4-oxalysine-N3-4-methoxyfumaroyl-L-2,3-diaminopropanoic-containing peptide analogues].

In order to improve the inhibitory activity of L-4-oxalysine(abbreviated as I-677) against clinically important pathogen Candida albicans, double-warheads peptide analogues containing I-677 and N3-4-methoxyfumaroyl-L-2,3-diaminopropanoic acid(FMDP) were designed based on the concept of "Illicit Transport" and peptide transport specificities of C. albicans. One compound of I-677-FMDP and seven compounds of I-677-AA-FMDP(AA = Nva, Leu, Val, Phe, Pro, D-Pgly, D, L-p-Cl-Phe) were synthesized and examined for antifungal activities. The results of anti-Candida albicans test in vitro of these double- warheads peptide analogues containing I-677 and FMDP showed very high activities against Candida albicans. The molar MIC (molar minimum inhibitory concentration) ratio of free I-677 to I-677-AA-FMDP is 40-770 and that of FMDP is 60-1130. The values of molar MIC of I-677-AA-FMDP varied from 6.56 x 10(-9) mol.disk-1 to 3.5 x 10(-10) mol.disk-1. The results of competitive antagonism studies indicated that I-677-AA-FMDP were transported into Candida albicans cells by the di-tripeptide permease and subsequently hydrolyzed by intracellular peptidases, releasing free I-677 and FMDP inside cells. The result of antienzymic degradation test in vitro of I-677-FMDP showed that compound I-677-FMDP was resistant to the hydrolysis by carboxypeptidase A.

Animals↗

PubMed1998

[Differentiation of cryptic species A and D of Anopheles dirus complex by polymerase chain reaction].

AIM: To distinguish cryptic species A and D of Anopheles dirus complex using polymerase chain reaction (PCR). METHODS: A diagnostic PCR assay of species was developed by use of three primers, one derived from highly conservative 5.8 S coding sequences and two from different interspecies sequence in the second internal transcribed spacer (ITS2) of ribosomal DNA. RESULTS: Using the PCR method, specific fragments were amplified in both species, the size of fragments is 374 bp for species A and 663 bp for species D. Thirty samples of species A from AFRIMS and HN laboratory colony and seven samples of the species D from Yunnan Province were correctly identified by PCR. Satisfactory results were obtained from the amount of DNA as little as 1/1,600 of extracted DNA of a single mosquito or 1/5 of DNA derived from one leg of a mosquito triturated in water. A total of 148 field-collected specimens of Anopheles dirus from Heping(HP), Baisha(BS), Loukui(LK), and Maoyang (MY) in Hainan Province revealed fragment characteristic of species A, while 30 specimens from Mengla (ML) in Yunnan Province showed the specific fragment of species D. CONCLUSION: A simple and reliable method was developed to identify cryptic species A and D of Anopheles dirus complex and it was further verified that Anopheles dirus from Hainan and Yunnan Provinces is the species A and the species D, respectively.

Animals↗

PubMed1998

[Continuous cultivation of a large number of Plasmodium falciparum gametocytes in carbon dioxide incubator].

AIM: To establish a method for continuously cultivating a large number of P. falciparum gametocytes in vitro using carbon dioxide incubator. METHODS: The number of gametocytes produced in experimental and control groups was compared after the addition of various concentrations of NaHCO3 to the culture medium. RESULTS: The gametocytes began to rise on day 5 of cultivation and reached a peak on day 11-13. The peak gametocyte loads were 1.9% +/- 0.6% and 1.3% +/- 0.4% (P < 0.05) in experimental and control group, respectively, indicating that the complete medium with 30 mmol/L sodium bicarbonate was beneficial to gametogenesis. The numbers of stages I-V gametocytes rose to a peak on d5, d7, d11, d13 and d15, respectively. On day 15 the percentage of stage V gametocytes was 7.1%-52.6% with an average of 24.3%. The ratio of macrogametocyte to microgametocyte was 12.8:1. The parasites were able to produce high gametocytaemia up to 24th subculture after thawing. Laboratory reared Anopheles stephensi fed through membrane on blood infected with P. falciparum were dissected, no oocyst was found in the midgut. CONCLUSION: A culture system which could consistently and stably produce a large number of gametocytes of P. falciparum was established.

Animals↗

PubMed1998

[Triterpenoids from the root bark of Aralia subcapitata].

OBJECTIVE: To investigate the chemical constituents of Aralia subcapitata. METHOD: The methanol extract of A. subcapitata was separated by repeated column chromatography, and the compounds were identified on the basis of spectroscopic analysis(IR, EI-MS, 1HNMR and 13CNMR) and physicochemical properties. RESULT: Four compounds were isolated from the root bark of A. subcapitata. Their structures were identified as 3 beta-hydroxy-oleana-11, 13(18)-dien-28-oic acid(I), 3-oxo-oleana-12-en-28-oic acid (II), oleanolic acid(III) and daucosterol(IV). CONCLUSION: All these compounds were isolated from this plant for the first time. Among them, compounds I and II were obtained for the first time from Aralia.

Aralia↗

PubMed1998

[Genetic characterization of an avian influenza A (H5N1) virus isolated from a sick goose in China].

Genetic analysis of viral HA gene showed that there were 22 nucleotide differences in HA gene between goose and human H5N1 viruses. The sequence analysis of amino acid on viral protein molecules indicated that there were 7 and 9 position differences between goose and human, chicken H5N1 viruses, respectively. All the three viruses share multiple basic amino acids (R-E-R-R-R-K-K-R) at the cleavage site between HA1 and HA2 domain, that is associated with highly pathogenic H5 avian viruses. Except one more glycosylation site located at 156 position in the chicken strain, there were 7 glycosylation sites at same positions in three virus HA protein molecules. The analysis of NA protein molecule indicated that the stalk region which extends from the viral membrane up to amino acid 85, human and chicken viruses had a 19 amino-acid deletion as compared with that of goose virus, while the goose NA gene was closely related to A/Parrot/Ulster/73 (H7N1) virus. Therefore, goose H5N1 virus HA and NA genes were avian in origin and were different from those of human and chicken H5N1 viruses. In our knowledge, this is the first time that the avian H5N1 virus was found causing influenza outbreak in goose. Why was A/Goose/Guangdong/2/96(H5N1) virus virulent for geese? It might be related to the substitution of amino acid located at 138 position near by RBS on HA protein molecule and 19 amino acids insertion on NA protein molecule as compared with those of human and chicken H5N1 viruses.

Amino Acid Sequence↗

PubMed1998

[Karyotype analysis on Iris lactea ssp. chinensis].

In this paper, the chromosome number, karyotype and chromosome volume of Iris lactea ssp. chinensis were reported. The normal diploid was 2n = 32. Karyotype formula was based on Levan's publication in 1964, k (2n) = 32 = 22 m + 8 sm + 2T. According to the method of Kuo SR, the species chromosome based on the relative length was 2n = 32 = 6L + 4 M2 + 18 M1 + 4 S which belong to "2A" type according to the Stebbins' karyotype classification. The AS.K% was 62.5% from Arano's method. The total volume of chromosome groups was 34.95 micron 3.

Base Sequence↗

PubMed1998

[Study on the Rheum palmatum volatile oil against HBV in cell culture in vitro].

The antiHBV effect of Rheum palmatum Volatile oil was studied by using 2215 cell line transfected with HBV DNA. At the same time MTT method was applied for the detection of cytoxicity of drugs, selecting acyclovir(ACV) as control medicine. It turns out that the toxic concentration of Rheum palmatum Volatile oil for 50% cells was (CD50) > 1.25 x 10(-1) g/L. When concentration was below 0.625 x 10(-1) g/L, the survival rate of cells was over 90%. The maximum inhibitory rates for HBsAg and HBeAg were 70.71 +/- 5.4% and 30.99 +/- 5.3% respectively. This shows Rheum palmatum Volatile oil possesses the effect of antiHBV in vitro.

Acyclovir↗

PubMed1998

[The effect of intracoronal bleaching on cervical periodontium of dogs]

OBJECTIVE:To study the effects of two intracoronal bleaching techniques on dog's cervical periodontium.METHODS: The experimental animal modles of intracoronal bleaching were established and pathological slides were made. The histological changes of dogs' periodontium were examined by means of light micro-scope. RESULTS: A year following intracoronal bleaching,the group received thermocatalytic bleaching showed:(1)resorption of cementum or dentine;(2)ankylosis,(3)infiltratin of substantial inflamatory cells into resorption areas.The group received walking bleaching showed:(1)localized resorption of alveolar bone;(2)lacuna-shaped resorption of cementum. CONCLUSION: Whether heated or not,intracoronal bleaching with bleaching with bleaching agent including 30% hydrogen peroxide may innitiate external cervical resorption of dog's teeth.

Journal Article↗

PubMed1998

Molecular study and prenatal diagnosis of alpha- and beta-thalassemias in Chinese.

Thalassemia is one of the most common single gene diseases worldwide. Populations in southern China and Taiwan have high prevalence rates of alpha- and beta-thalassemias. This review summarizes the current status of molecular studies, carrier screening, and prenatal diagnosis of thalassemia in Chinese. There are three genotypes of alpha-thalassemia 1 and at least six of alpha-thalassemia 2 in Chinese. For alpha-thalassemia 1, the South-East Asian deletion is the most common, followed by the Thai then Philippino deletions. For alpha-thalassemia 2, the rightward deletion is the most common, followed by the leftward deletion, and the nondeletional defects Hb Constant Spring and Hb Quong Sze. Twenty-eight different beta-thalassemia mutations have been reported. Four mutations, IVS-II-654 (C-->T), codons 41/42 frameshift (-TCTT), and nonsense codons 17 (A-->T) and -28 (A-->G), account for more than 90% of mutant alleles. For detection of alpha-thalassemia, polymerase chain reaction-related techniques are mainly used. Southern blot hybridization is still useful, especially for prenatal diagnosis. For detection of beta-thalassemia mutations, analysis of amplification-created restriction sites and reverse dot blot hybridization have been extensively used. In Taiwan, a national screening program incorporating hematological and molecular biological methods for thalassemia detection in pregnant women has been in progress for 5 years. Prenatal diagnosis has been performed in more than 1,800 pregnancies, including 1,500 cases at risk for homozygous alpha-thalassemia 1 and 300 for beta-thalassemia major, resulting in early prenatal diagnosis and termination of pregnancies affected with homozygous alpha-thalassemia 1 and an approximately 70% decrease in the number of newborns affected with beta-thalassemia major. In mainland China, only one large-scale screening program is in place. Characterization of undefined alleles, a higher awareness of the disease among physicians and the general public, and improvement of the service network will be important for early prenatal diagnosis and prevention of the disease in the future.

China↗

PubMed1998

In vitro and in vivo evaluations of intestinal barriers for the zwitterion L-767,679 and its carboxyl ester prodrug L-775,318. Roles of efflux and metabolism.

The barriers to oral delivery of the hydrophilic zwitterion L-767, 679 (I) and its carboxyl ester prodrug L-775,318 (II) were examined. In the Caco-2 cell model, transport of II, but not I, was strongly oriented in the secretory direction. The basal-to-apical transport of II displayed saturable kinetics and was markedly inhibited by verapamil and quinidine, known P-glycoprotein inhibitors. In Caco-2 cells, metabolism of I was not observed, whereas hydrolysis of II was modest (</=20%). In the in situ rat intestinal loop model, verapamil did not affect the absorption of I but significantly increased the absorption of II. I was resistant to intestinal metabolism, whereas II underwent hydrolysis partially in rat lumen but more extensively in rat intestinal tissue and blood. In vitro metabolism studies indicated that verapamil also inhibited the hydrolysis of II in rats. The inhibition was relatively specific for the intestinal and not the luminal esterases. These results suggested that the intestinal absorption of I was limited not by intestinal efflux or metabolism but more likely by the low lipophilicity of I. However, an efflux system, likely mediated by P-glycoprotein, played an important role in limiting the absorption of II. In rats, metabolism served as an additional barrier to the absorption of II. Verapamil increased the intestinal absorption of the prodrug by inhibiting the efflux system in the two models studied, as well as possibly inhibiting metabolism in rats. For the first time, secretory transport was identified as a cause of the failure to increase the absorption of a lipophilic and cationic prodrug developed to overcome the absorption problem.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed1998

Immunological characterization of cell-surface and soluble forms of membrane type 1 matrix metalloproteinase in human breast cancer cells and in fibroblasts.

Membrane type (MT) 1 matrix metalloproteinase (MMP) activates progelatinase A (pro-MMP-2), a type IV collagenase, on the cell surface of tumors; however, its function in breast cancer progression and metastasis is not fully understood. To examine the expression of MT1-MMP in breast cancer cells and fibroblasts, a specific rabbit antibody (Ab) directed against a unique synthetic peptide derived from the human MT1-MMP catalytic domain was produced, purified, and characterized. This Ab is not likely to cross-react with MT2-, MT3-, or MT4-MMP or any other MMPs. MT1-MMP expression and pro-MMP-2 activation were stimulated by concanavalin A in two human breast carcinoma cell lines (BT549 and MDA-MB-231) and in normal human fetal-lung fibroblasts (HFL-1) and were slightly upregulated by breast cancer cell-fibroblast interactions. Both pro-MT1-MMP in plasma membrane (63.4 kDa) and the soluble forms of the enzyme in culture medium (57.6 and 25-30 kDa) were detected by immunoblot analysis, suggesting that cell-surface MT1-MMP exhibits an active conformation without the removal of its propeptide domain and that the mature enzyme is shed into the medium. In breast cancer cells, MT1-MMP and a recombinant catalytic domain of MT1-MMP were unable to activate pro-matrilysin, indicating that MT1-MMP is not a universal activator of all MMPs. MT1-MMP may play an important role in the invasive growth and spread of breast cancer cells by specifically activating pro-MMP-2 to cleave the connective-tissue barrier. Furthermore, use of the specific Ab may aid in the investigation of the role of MT1-MMP in human tumors.

Amino Acid Sequence↗

PubMed1998

Microsomal epoxide hydrolase polymorphism and risk of spontaneous abortion.

We conducted a nested case-control study to examine the association of microsomal epoxide hydrolase polymorphism with spontaneous abortion. The analysis included 127 cases and 107 controls from a rural community in China. The prevalence of the homozygous wild-type (AA), the heterozygous variant (Aa), and the homozygous variant (aa) in exon 3 of epoxide hydrolase was 13.4%, 34.6%, and 52.0% in cases and 27.1%, 30.8%, and 42.1% in controls, respectively. In contrast, the variant genotypes in exon 4 of epoxide hydrolase were less frequent in cases than controls. Using women with genotype AA as the referent, the adjusted odds ratio of spontaneous abortion was 2.69 [95% confidence interval (CI) = 1.33-5.42] for those with genotype Aa or aa in exon 3; but it was 0.45 (95% CI = 0.22-0.94) for those with genotype Aa or aa in exon 4, indicating that the two variants have opposite associations with spontaneous abortion. The findings persisted after adjustment for age, education, parity, smoking, alcohol use, occupation, and pesticide exposure, as well as in subgroup analysis. Moreover, for the variant genotypes Aa or aa in exon 3, the odds ratio was twice as great in those cases with three or more spontaneous abortions than in those with fewer spontaneous abortions.

Abortion, Spontaneous↗

PubMed1998

Homology modeling of tissue-type plasminogen activator K1 domain and studies on the interactions between kringles and lysine.

The 3-D structure of t-PA K1 domain was predicted by the method of homology modeling. The putative lysine-binding pockets of t-PA K1, UK K, PLG K1 and K4 were determined by superimposing their 3-D structures to that of t-PA K2 domain, of which the lysine-binding pockets had been revealed previously. After that the key residues of lysine-binding pockets of kringles were identified. The structural analyses showed that both the electrostatic potential and hydrophobic complementarity were well matched between lysine and the binding pockets of t-PA K2, PLG K1 and K4, but for t-PA K1 and UK K domains the complementarity did not match well in one or both respects. It is proposed that this is the reason that t-PA K1 and UK K domains do not bear the ability to bind lysine. With the respect of improving the affinity for fibrin, new types of mutants of t-PA K1 and UK K domains were designed, and structural changes caused by mutation were predicted by simulating the residue replacements. The mutant structural models demonstrated that the molecular design was reasonable.

Amino Acid Sequence↗

PubMed1998

Predictors of long-term change in functional status after coronary artery bypass graft surgery in women.

A cohort of 164 women who had undergone coronary artery bypass graft surgery (CABG) was followed for one year to examine changes in functional status and determine the relative influence of clinical, psychosocial and sociodemographic factors on change in functional status outcomes between 6 and 12 months after surgery. Clinical, psychosocial, sociodemographic and preoperative functional status data were collected by written questionnaire and personal interview at the time of surgery and again at 6 and 12 months after CABG. Functional status scores improved significantly from before to 6 months after CABG. Between 6 and 12 months post-CABG 65% sustained or continued to experience improvement in physical functioning, 83% in social and leisure activities, and 54% in psychological functioning. Predictors of sustained improvement in physical functioning were being married, younger age, low 6-month functioning, having an ejection fraction of 50% or greater, and being white. The significant predictors of sustained improvement in social and leisure activities and psychological functioning were being married and low 6-month psychological functioning, respectively. These data suggest that interventions to improve long-term outcomes in women undergoing CABG should take into account not only their age, functional capacity and level of functioning at 6 months post-CABG, but also their race and marital status as potential risk factors for long-term functional status disability.

Age Factors↗

PubMed1998

Design and evaluation of a portable rigid forced-air warming cover for prehospital transport of cold patients.

Forced-air warming is promising for use during transport of cold patients. However, the current soft covers may be easily damaged in the nonhospital environment. Two rigid covers were designed to direct heat to the torso and thighs. Five subjects (one female) were heated with an AC powered heater (Bair Hugger 505, Augustine) and either a soft cover or the rigid covers (with heat input at the head or abdomen). Compared to the soft cover, the rigid cover (with heat input at the abdomen) provided similar heat delivery but a higher mean skin temperature. We conclude that the portable rigid covers are efficient for treatment of cold victims during pre-hospital transport.

Air↗

PubMed1998

Effects of soy isoflavones on estrogen and phytoestrogen metabolism in premenopausal women.

Isoflavones and lignans are soy phytoestrogens that have been suggested to be anticarcinogenic. The mechanisms by which they exert cancer-preventive effects may involve modulation of estrogen synthesis and metabolism. To evaluate this hypothesis, a randomized, cross-over soy isoflavone feeding study was performed in 12 healthy premenopausal women. The study consisted of three diet periods, each separated by a washout of approximately 3 weeks. Each diet period lasted for three menstrual cycles plus 9 days (averaging approximately 100 days), during which subjects consumed their habitual diets supplemented with soy protein powder providing 0.16 (control diet), 1.01, or 2.01 mg of total isoflavones per kg of body weight per day (10+/-1.1, 65+/-9.4, or 129+/-16 mg/day, respectively). A 72-h urine sample was collected during the midfollicular phase (days 7-9) of the fourth menstrual cycle in each diet period. Urine samples were analyzed for 10 phytoestrogens and 15 endogenous estrogens and their metabolites by a capillary gas chromatography-mass spectrometry method. Urinary excretion of isoflavonoids and lignans significantly increased with increased isoflavone consumption. Compared with the control diet, increased isoflavone consumption decreased urinary excretion of estradiol, estrone, estriol, and total estrogens, as well as excretion of the hypothesized genotoxic estrogen metabolites, 16alpha-hydroxyestrone, 4-hydroxyestrone, and 4-hydroxyestradiol. Of importance are the observations of a significant increase in the 2-hydroxyestrone/16alpha-hydroxyestrone ratio and a decrease in the genotoxic/total estrogens ratio. These data suggest that soy isoflavone consumption may exert cancer-preventive effects by decreasing estrogen synthesis and altering metabolism away from genotoxic metabolites toward inactive metabolites.

Adult↗