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Biomedical subjects

E Zhang

Publications and source records attributed to E Zhang.

At least 19 recordsLinked to original sources
PubMed2006

Ga-assisted synthesis and optical properties of ZnO submicron- and nanotowers.

Tower-like ZnO submicron- and nanostructures were synthesized by simply evaporating a mixture of Zn and Ga. Scanning electron microscopy and transmission electron microscopy observations showed that the regular hexagonal tower-like structure is likely to be made up in a layer-by-layer fashion and consist of sheets. According to our experiments, the amount of Ga has a large effect on their morphologies. The growth of such tower-like structures is ascribed to the vapor-solid mechanism. The introduction of Ga hinders the growth of ZnO along the [0001] direction, resulting in the formation of the novel tower-like structures. In addition, the photoluminescence of such structures shows a strong green-light emission.

Journal Article↗
PubMed2006

Successful liver transplantation following medical management of portopulmonary hypertension: a single-center series.

Severe portopulmonary hypertension (POPH) is an absolute contraindication to orthotopic liver transplantation (OLT). Vasodilators have been used, but the safety of subsequent transplantation and the reversibility of pulmonary hypertension after transplantation are uncertain. This study examined the feasibility and post-transplant effects of liver transplantation following medical control of POPH. Eight consecutive patients (three females and five males, ages 39-51) with POPH as their only contraindication to transplantation were treated with continuous intravenous epoprostenol. Liver transplantation was considered if the mean pulmonary artery pressure (PAM) was lowered to <35 mmHg. Epoprostenol 2-8 ng/kg/min successfully improved hemodynamics in seven of eight patients, usually within 6.5 months of initiating therapy. PAM declined from an average of 43-33 mmHg (p=0.03); mean pulmonary vascular resistance declined from 410 to 192 dyn s cm-5 (p=0.01) and cardiac output increased from 6.6 to 10 L/min (p=0.02). Six of the seven responders were actively listed for liver transplantation. Two died on the waiting list; the remaining four were transplanted and remain alive and well 9-18 months post-OLT-two without vasodilators, and two on oral medication. We conclude that pulmonary vasodilators permit safe liver transplantation in some cases, and that POPH may be reversible after transplantation.

Adult↗
PubMed2006

Hereditary haemorrhagic telangiectasia: mutation detection, test sensitivity and novel mutations.

BACKGROUND: Hereditary haemorrhagic telangiectasia (HHT) is a genetic disorder present in 1 in 8000 people and associated with arteriovenous malformations. Genetic testing can identify individuals at risk of developing the disease and is a useful diagnostic tool. OBJECTIVE: To present a strategy for mutation detection in families clinically diagnosed with HHT. METHODS: An optimised strategy for detecting mutations that predispose to HHT is presented. The strategy includes quantitative multiplex polymerase chain reaction, sequence analysis, RNA analysis, validation of missense mutations by amino acid conservation analysis for the ENG (endoglin) and ACVRL1 (ALK1) genes, and analysis of an ACVRL1 protein structural model. If no causative ENG or ACVRL1 mutation is found, proband samples are referred for sequence analysis of MADH4 (associated with a combined syndrome of juvenile polyposis and HHT). RESULTS: Data obtained over the past eight years were summarised and 16 novel mutations described. Mutations were identified in 155 of 194 families with a confirmed clinical diagnosis (80% sensitivity). Of 155 mutations identified, 94 were in ENG (61%), 58 in ACVRL1 (37%), and three in MADH4 (2%). CONCLUSIONS: For most missense variants of ENG and ACVRL1 reported to date, study of amino acid conservation showed good concordance between prediction of altered protein function and disease occurrence. The 39 families (20%) yet to be resolved may carry ENG, ACVRL1, or MADH4 mutations too complex or difficult to detect, or mutations in genes yet to be identified.

Activin Receptors, Type II↗
PubMed2006

[Neurofibromatosis type 2].

OBJECTIVE: To recognise the predisposing factors, clinical manifestations, diagnosis and treatment of neurofibromatosis type 2 (NF2). METHOD: The clinical data of one NF2 case was reported and the literatures were also reviewed. RESULT: The patient was diagnosed at a much later stage than onset. Progressive hearing loss and tinnitus were the initial symptoms. MRI scan indicated space-occupying lesions in the bilateral cerebellopontine angles, bilateral cavernous sinuses and bilateral cervical parts of the patient. The patient was diagnosed as NF2 according to the National Institutes of Health (NIH) criteria, and received operation on the left acoustic tumor. The tumor was proved to be schwannomas by pathological test. The hearing loss and the facial nerve paralysis (House-Brackmann II) had appeared after operation. CONCLUSION: NF2 is an autosomal dominant, highly penetrant disease which is characterized by bilateral vestibular schwannomas. Early diagnosis and management for tumor is very important for survival and hearing preservation. The "golden standard" in terms of diagnostic precision is the magnetic resonance imaging (MRI) scan with gadolinium enhancement.

Adult↗
PubMed2001

Localization of heat shock protein 20 in swine carotid artery.

BACKGROUND: Cyclic nucleotides can relax vascular smooth muscle by mechanisms distal to myosin regulatory light chain (MRLC) phosphorylation. This mechanism, termed relaxation without MRLC dephosphorylation, may be regulated by ser16 phosphorylation of heat shock protein 20 (HSP20). RESULTS: Confocal imaging of HSP20 in smooth muscle tissues revealed that HSP20 was present throughout the cytoplasm, although some focal regions of the cytoplasm were found to contain more HSP20 than the remaining cytoplasm. The distribution of HSP20 within the cytoplasm was not altered by histamine, forskolin, or nitroglycerin. CONCLUSION: Cytoplasmic localization of HSP20 is consistent with a potential function of HSP20 as a regulator of smooth muscle contractile force.

Animals↗
PubMed2001

Angiogenic growth factor messenger ribonucleic acids in uterine natural killer cells.

Angiogenesis is essential for endometrial growth and repair, and disruption of this process may lead to common disorders of women, including menorrhagia and endometriosis. In pregnancy, failure of the endometrial spiral arterioles to undergo remodeling leads to preeclampsia. Here we report that in addition to vascular endothelial growth factor A (VEGF-A), human endometrium expresses messenger ribonucleic acids (mRNAs) encoding VEGF-C, placenta growth factor (PlGF), the angiopoietins, angiopoietin 1 (Ang1) and Ang2, and the receptors VEGFR-3 (Flt-4), Tie 1, and Tie 2. Levels of VEGF-C, PlGF, and Tie 2 changed during the menstrual cycle. Intense hybridization for VEGF-C and PlGF mRNAs was found in uterine nature killer cells in secretory phase endometrium and for Ang2 mRNA in the same cells in the late secretory phase. Interleukin-2 (IL-2) and IL-15 up-regulated VEGF-C, but not PlGF or Ang2, mRNA levels in isolated NK cells. Conditioned medium from decidual NK cells did not induce human umbilical vein endothelial cell apoptosis. These results indicate that human endometrium expresses a wide range of angiogenic growth factors and that uterine nature killer cells may play an important role in the abnormal endometrial angiogenesis that underlies a range of disorders affecting women.

Angiogenesis Inducing Agents↗
PubMed2001

[The complexity measure and its application to EEG analysis].

In this paper are reviewed the conceptions, characteristics and application of the complexity measure in studying EEG. The reviewers expound the advantages and problems of using complexity measure in the analysis of EEG in different physiological states and deem it a new way to study and understand the human brain function.

Algorithms↗
PubMed2001

[The resource conservation and utilization of wild Sika deer in China].

There had once been six subspecies of Sika deer (Cervus nippon) in China, but now only three subspecies in wild, i.e. Northeast China, Sichuan and South China subspecies, and all the three subspecies lie in the endangered status. Most of population are very small, and their distribution ranges have already been broken up into many isolated patches, furthermore, their habitats have been deteriorating. So it is very necessary to enhance the protecting of wild sika deer. Some endangered and small populations of wild deer can be saved by inflows of domestic health deer. Wild deer can help farm deer to acquire some good characters again by interbreeding between them. So we think that the purposes of protecting wild population and developing domestic population can be achieved by cooperating between reserves and deer farms.

Animals↗
PubMed2001

[Important prognostic factors in patients with skull base erosion from nasopharyngeal carcinoma after radiotherapy].

OBJECTIVE: To evaluate the long-term outcome and prognostic factors in patients with skull base erosion from nasopharyngeal carcinoma (NPC) after initial radiation therapy. METHODS: From January 1985 to December 1986, 100 patients (71 male, 29 female) with the diagnosis of NPC were found to have skull base erosion from computed tomography (CT). The mean age was 41 (16-66) years. Ninety-six patients had World Health Organization (WHO) type III undifferentiated carcinoma while four had type I carcinomas. Metastatic workup including chest radiography, liver ultrasound and liver function test were negative. All patients underwent external beam radiotherapy alone to 66-80 Gy over 6-8 weeks. Daily fraction size of 2 Gy was delivered utilizing cobalt-60 or linear accelerator. No patient received chemotherapy. All patients were followed up at regular intervals after irradiation. Median follow-up was 22.3 months (2 months-174 months). Overall survival of the cohort was computed by the Kaplan-Meier method. Potential prognostic factors on survival were examined. Multivariate analyses was performed using Cox regression model. RESULTS: One, three, five, and ten year overall survival rates for the cohort were 79%, 38%, 27% and 13%, respectively. However, in the sub-group of patients with both anterior cranial nerves (I-VIII) and posterior cranial nerve (IX-XII) involvement had a five-year survival of only 7.7%. Causes of death included local recurrence (59 patients), distant metastases (21 patients), both local recurrence and distant metastases (1 patient) and unrelated causes (5 patients). After multivariate analysis, complete recovery of cranial nerve involvement, cranial nerves palsy and recovery of headache after irradiation were found to be independent prognostic factors in this cohort. CONCLUSION: This report presents one of the longest follow-ups of patients with nasopharyngeal carcinoma invading skill base. It demonstrates the importance of cranial nerves involvement as well as recovery of headache and cranial nerve palsy. These factors should be evaluated carefully from history and physical examination as well as imaging studies. Currently available magnetic resonance imaging (MRI) is highly recommended as an additional test. A subgroup of patients with skull base involvement had long-term survival after radiotherapy alone. More aggressive strategy such as combined chemo-radiotherapy and altered fractionation radiotherapy may improve outcome in patients with poor prognostic factors.

Adolescent↗
PubMed2000

Pyrido[2,3-d]pyrimidin-7-one inhibitors of cyclin-dependent kinases.

The identification of 8-ethyl-2-phenylamino-8H-pyrido[2, 3-d]pyrimidin-7-one (1) as an inhibitor of Cdk4 led to the initiation of a program to evaluate related pyrido[2, 3-d]pyrimidin-7-ones for inhibition of cyclin-dependent kinases (Cdks). Analysis of more than 60 analogues has identified some clear SAR trends that may be exploited in the design of more potent Cdk inhibitors. The most potent Cdk4 inhibitors reported in this study inhibit Cdk4 with IC(50) = 0.004 microM ([ATP] = 25 microM). X-ray crystallographic analysis of representative compounds bound to the related kinase, Cdk2, reveals that they occupy the ATP binding site. Modest selectivity between Cdks is exhibited by some compounds, and Cdk4-selective inhibitors block pRb(+) cells in the G(1)-phase of the cell division cycle.

Adenosine Triphosphate↗
PubMed2000

The crystal structure and amino acid sequence of dehaloperoxidase from Amphitrite ornata indicate common ancestry with globins.

The full-length, protein coding sequence for dehaloperoxidase was obtained using a reverse genetic approach and a cDNA library from marine worm Amphitrite ornata. The crystal structure of the dehaloperoxidase (DHP) was determined by the multiple isomorphous replacement method and was refined at 1.8-A resolution. The enzyme fold is that of the globin family and, together with the amino acid sequence information, indicates that the enzyme evolved from an ancient oxygen carrier. The peroxidase activity of DHP arose mainly through changes in the positions of the proximal and distal histidines relative to those seen in globins. The structure of a complex of DHP with 4-iodophenol is also reported, and it shows that in contrast to larger heme peroxidases DHP binds organic substrates in the distal cavity. The binding is facilitated by the histidine swinging in and out of the cavity. The modeled position of the oxygen atom bound to the heme suggests that the enzymatic reaction proceeds via direct attack of the oxygen atom on the carbon atom bound to the halogen atom.

Amino Acid Sequence↗
PubMed2000

[Effect of fish oil supplementation on fatty acid composition and neurotransmitters of growing rats].

In order to observe the change of brain fatty acid composition and neurotransmitter by DHA supplementation during the development stage of young rats, pregnant rats were randomly divided into four groups: normal control group (O), low (L), medium (M) and high (H) dose-DHA supplemented groups. The fatty acids composition, the levels of 5-hydroxy-tryptamine (5-HT), dopamine (DA), norepinephrine (NE) and somatostatin (SS) in ceretral cortex and hippocampus of offsprings were measured. The body weight of pregnant rats and offsprings were also observed. The results showed that DHA content of brain homogenate and the levels of 5-HT, DA and SS in hippocampus of experimental young rats were significantly higher than those of the control group. And the body weight of young rats in the three DHA-supplemented groups were retarded in different degree. It was concluded that DHA supplementation changed the fatty acid composition and increased the levels of 5-HT, DA and SS in hippocampus. Proper ratio of n-3 and n-6 fatty acids in dietary supplementation should be considered.

Animals↗
PubMed2000

[Modification of surface of Dacron materials by UV irradiation for prevention of microbial adhesion].

UV irradiation grafting method was used to modify the surface of Prosthetic Valve materials (Dacron) for prevention of bacteria-adhesion, and PEG was introduced to the surface of Dacron by this method. The result showed that the chemical magnifying effect of PEG improved the grafting of heparin on the material surface. This method can obviously reduce the number of adherent bacteria.

Bacterial Adhesion↗
PubMed1999

OmpF changes and the complexity of Escherichia coli adaptation to prolonged lactose limitation.

The disaccharide lactose has no specific diffusion pathway across the outer membrane of Escherichia coli. At least three classes of spontaneous mutation affecting outer membrane permeability arose with each of three independent E. coli populations adapting to prolonged lactose limitation in chemostats. Both structural and regulatory mutations affecting OmpF porin predominated in isolates after 210-280 generations of culture. Six types of ompF mutation were found, including in-frame deletions and substitutions at Arg82 and Asp113, all affecting the channel constriction residues of OmpF. Isolates had increased susceptibility to antibiotics and were affected in the quantity of OmpF, LamB and OmpA proteins. A minimum of three or four mutations was evident in all isolates after 280 generations in a lactose-limited environment, in addition to lac mutations defined in previous studies.

Adaptation, Physiological↗
PubMed1999

Bound structures of novel P3-P1' beta-strand mimetic inhibitors of thrombin.

The X-ray crystal structures of four beta-strand-templated active site inhibitors of thrombin containing P1' groups have been determined and refined at about 2.1-A resolution to crystallographic R-values between 0.148 and 0.164. Two of the inhibitors have an alpha-ketoamide functionality at the scissile bond; the other two have a nonhydrolyzable electrophilic group at the P1' position. The binding of lysine is compared with that of arginine at the S1 specificity site, while that of D,L-phenylalanine enantiomorphs is compared in the S3 region of thrombin. Four different P1' moieties bind at the S1' subsite in three different ways. The binding constants vary between 2.0 microM and 70 pM. The bound structures are used to intercorrelate the various binding constants and also lead to insightful inferences concerning binding at the S1' site of thrombin.

Aza Compounds↗
PubMed1999

Mechanism of triclosan inhibition of bacterial fatty acid synthesis.

Triclosan is a broad-spectrum antibacterial agent that inhibits bacterial fatty acid synthesis at the enoyl-acyl carrier protein reductase (FabI) step. Resistance to triclosan in Escherichia coli is acquired through a missense mutation in the fabI gene that leads to the expression of FabI[G93V]. The specific activity and substrate affinities of FabI[G93V] are similar to FabI. Two different binding assays establish that triclosan dramatically increases the affinity of FabI for NAD+. In contrast, triclosan does not increase the binding of NAD+ to FabI[G93V]. The x-ray crystal structure of the FabI-NAD+-triclosan complex confirms that hydrogen bonds and hydrophobic interactions between triclosan and both the protein and the NAD+ cofactor contribute to the formation of a stable ternary complex, with the drug binding at the enoyl substrate site. These data show that the formation of a noncovalent "bi-substrate" complex accounts for the effectiveness of triclosan as a FabI inhibitor and illustrates that mutations in the FabI active site that interfere with the formation of a stable FabI-NAD+-triclosan ternary complex acquire resistance to the drug.

Enoyl-(Acyl-Carrier-Protein) Reductase (NADH)↗