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Biomedical subjects

L He

Publications and source records attributed to L He.

At least 145 records · Page 8Linked to original sources
PubMed2001

[Study on maxillofacial impact injury associated with brain injury].

OBJECTIVE: The purpose was to study the mechanism and the characteristics of brain damage associated with maxillofacial injury under the impacting load of middle face. METHODS: Eighteen rabbits were subjected to impacting on left middle face with pneumatic impact device, which were horizontally located on the ground. The impact velocities respectively were 4.77 m/s +/- 0.53 m/s (group A), 9.16 m/s +/- 0.65 m/s (group B) and 13.95 m/s +/- 0.67 m/s (group C). The acceleration of head and stress of encephalic was monitored during the impact period. The pathological characteristics of correlative tissues were examined in detail 6 hours after impacting. The contents of LPO, SOD and NO in blood and water in brain were measured at the same time. RESULTS: The contents of LPO and SOD in blood significantly increased along with the increasing of impact velocity (P < 0.05). The same pattern was observed in the changing of water content of brain (P < 0.05). But the contents of NO in blood reduced when the impact velocity increased (P < 0.05). The animals of group A showed single fracture of middle face bone, while Group B showed multiple fractures of middle face bone. Group C represented severe maxillofacial injury associated with brain damage. The pathological damage of brain became more serious along with the increase of impact velocity. The peak value of head acceleration and encephalic stress of group C were higher than that of group A and group B (P < 0.05). CONCLUSION: The responses of head acceleration and encephalic stress resulting from middle face impacting might play a key role in brain injury associated with maxillofacial injury.

Animals↗
PubMed2001

[Effect of alpha-lipoic acid on the apoptosis of PC12 cells induced by 6-hydroxydopamine].

PC12 cell line, a clonal cell line derived from a pheochromocytoma of rat adrenal medulla, was used as a model of dopaminergic neuron in vitro to study the effect of alpha-lipoic acid on the 6-OHDA induced apoptosis. The results from MTT method show that 6-OHDA decreased the cell survival rate obviously. Through TUNEL (TdT-mediated dUTP-biotion nick end labeling) and Flow cytometer (FCM) detection, we found that 6-OHDA triggered cell apoptosis and induced necrosis. It was confirmed by the different percentage of cell survival rate and apoptosis concluded from FCM and MTT. alpha-lipoic acid was used as antioxidant to protect the cell from 6-OHDA's injury. The result indicateed that alpha-lipoic acid can partly prevent apoptosis induced by 6-OHDA but fail to prevent necrosis since it can decrease the apoptotic cell from 20.09% to 3.09%, just as increased cell survival rate from 56.8% to 72.6% but can not reach the normal level showed by MTT assay. Biochemical approach showed the cell's antioxidant ability especial for SOD activity and GSH content increased after the treatment of alpha-lipoic acid. The data suggest that alpha-lipoic acid may protect PC12 cells from apoptosis induced by 6-OHDA through the antioxidant path.

Animals↗
PubMed2001

[The clone and comparison of very virulent plus Marek's disease virus(vv+ DMV)648 strain glycoprotein E(gE) gene].

The glycoprotein E(gE) gene of very virulent plus Marek's Disease (vv+ MDV) 648 strain was amplified by polymerase chain reaction (PCR) and cloned into pUC18 vector. The gE sequence was determined and analysed. The whole length of 648 strain gE gene is 1494 base pairs. The protein encoded by gE gene has several features characteristic of a membrane-associated glycoprotein. It contains eight potential glycosylation sites, a markedly hydrophobic region at the N terminus that could function as a signal peptide and a hydrophobic segment (aa 391-419) at C terminus that could function as a transmembrane anchor element. Comparison of the gE between 648 strain and virulent MDV (vMDV) GA strain revealed that gE sequence is conserved in MDV serotype 1, there are only two basepairs different, (at bp 512 and 1472), which induce two amino acids changed respectively (at aa 171 and 491). The function of 648 strain gE and the difference of gE between 648 strain and GA strain is on study.

Amino Acid Sequence↗
PubMed2001

[Effect of acryl thiourea on liver pathologic changes in mice infected with Schistosoma japonicum].

OBJECTIVE: To observe the effect of acryl thiourea, an inhibitor of phenol oxidase, on pathological changes in the liver of mice infected with Schistosoma japonicum. METHODS: From day 22 to day 42 postinfection with cercariae, the mice of the acryl thiourea group were each injected i.p. with acryl thiourea at a dose of 300 mg/kg every other day. The mice were killed on the 42nd day postinfection to observe the pathological changes in the liver. RESULTS: Compared to the infected control group, the liver tissue of the acryl thiourea group showed scattered foci of inflammatory cell infiltration, the mean diameter and area of the foci were significantly reduced (P < 0.01), and there were no eggs in the center of the foci except for some granules. CONCLUSION: After i.p. injections of acryl thiourea, no typical egg granuloma was found in the liver of infected mice. This was possibly due to the inhibition of schistosome phenol oxidase activity and so the female adult schistosomes could not produce normal eggs.

Animals↗
PubMed2001

[Anatomic characteristics of lingual artery and midline glossectomy].

OBJECTIVE: To investigate the relationship between anatomic characteristics of lingual artery and midline glossectomy, for the purpose of increasing operative safety. METHODS: (1) 16 extraoral dissections of the submandibular region were performed on 8 human cadavers and to observe the origin and distribution of lingual artery. (3) The lingual artery was divided into three segments, and the length and adjacent organs were observed and measured. RESULTS: The whole length of lingual artery was (92.88 +/- 13.53) mm; At points of foramen cecum of the tongue, 5 mm and 10 mm prior to foramen cecum, 10 mm behind foramen cecum, and at adjacent part between root of the tongue and epiglotic vallecula, the distances between lingual artery and midline of the tongue were separately measured. The distances were (11.00 +/- 4.95) mm, (8.56 +/- 3.51) mm, (7.78 +/- 3.15) mm, (13.00 +/- 3.28) mm, (15.22 +/- 3.11) mm. The distances between lingual artery and the surface of tongue were (21.4 +/- 5.59) mm, (22.11 +/- 6.74) mm, (22.56 +/- 7.81) mm, (16.56 +/- 5.57) mm, (2.56 +/- 0.73) mm respectively. CONCLUSION: During the midline glossectomy, the lingual artery is easier to be damaged at the position where the root of tongue adjoining epiglottic vallecala. The operation should be done within 10 mm below the surface, 7 mm lateral to the midline, to avoid the damage of lingual artery.

Arteries↗
PubMed2001

[Study on the spectral properties of nanocrystals Dy0.5Sr0.5CoO3-Y].

The spectral properties of nanocrystallines Dy0.5Sr0.5CoO3-Y were studied. The results show that the band edge of emission spectra is blue shift when the size of particles decrease to nanometer. The infrared absorption peak fission of nanocrystallines and the XRD diffraction peak of nanocrystallines were widen than microcrystallines. It was appeared as quantum size effect.

Cobalt↗
PubMed2001

[In situ IR study of the reaction behavior of clusters [VnCr3-n (mu 3-O) (mu-O2CCH3)6(THF)3]X[n = 0-3, X = Cl-, ClO4-, (VO5)0.5-] and [VnFe3-n(mu 3-O) (mu-O2CCH3)6(THF)3]X(n = 0-3, X = Cl-) in nitrogen atmosphere].

The reaction behavior of the title complexes have been investigated by means of in situ IR in nitrogen atmosphere. It has been found that they enabled the acetic acid to convert to acetone and methane in different temperatures. The results indicate that the sequence of the ketonization reaction activity for the clusters was [V3OAT] > [VFe2OAT], [V2CrOAT] > [Fe3OAT], [VCr2OAT] > [Cr3OAT] [OAT = (mu 3-O) (mu-O2CCH3)6 (THF)3], and the sequence of the methanation reaction activity for the clusters was [Cr3OAT] > [VCr2OAT], [V2CrOAT] > [V3OAT] > [VFe2OAT], [Fe2OAH]. The ketonization reaction activity of [Fe3OAT] were obviously lower than that of [Fe3OAH] [OAH = (mu 3-O) (mu-O2CCH3)6 (H2O)3] and the methanation reaction activity of [Cr3OAT] were also much lower than that of [Cr3OAH]. The difference between [Fe3OAH], [Cr3OAT] and [Fe3OAH], [Cr3OAH] mentioned above were discussed.

English Abstract↗
PubMed2001

[In situ IR study of the reaction behavior of transition metal oxides-propionic acid system, Fe2Cr(mu 3-O) (mu-O2CC2H5)6(H2O)3Cl.xH2O and Cr3 (mu 3-O) (mu-O2CC2H5)6(H2O)3NO3.xH2O].

The reaction behavior of the title complexes have been investigated by means of in situ IR in nitrogen atmosphere. It has been found that they enabled the propionic acid to convert to acetaldehyde and pentanone in different temperature. The sequence of the ketonization reaction activity for metal oxides Fe3O4 > MnO2 > Cr2O3 > Co2O3 > Ni2O3 has analogy to that for metal clusters [Fe2MnOPH] > [Fe3OPH] > [Fe2CrOPH] > [Fe2CoOPH] > [Fe2NiOPH] > [Cr3OPH][OPH = (mu 3-O)(mu-O2CC2H5)6(H2O)3]. For the ketonization reactions, the reaction temperatures of transition-metal oxides were much higher than that of corresponding metal clusters [Fe2MOPH]. It has been verified that the active component of metal cluster [Fe2MOPH] is not the corresponding transition-metal oxides. The difference between Fe3O4 and Fe2O3 which catalyze the conversion of propionic acid to acetaldehyde and pentanone respectively were demonstrated.

English Abstract↗
PubMed2001

[Establishing a model of neutropenia rat with Pseudomonas aeruginosa pneumonia and a study on its inflammatory reaction].

OBJECTIVE: To establish an animal model and study the inflammatory reaction of P. Aeruginosa pneumonia in neutropenia rats. METHODS Fifty SD rats were randomly divided into two groups: drug-treated group and control CON group. Drug-treated group was given a combination regimen of cyclophosphamide (15 m x kg(-1) d(-1)) and cortisone acetate (100 mg x kg(-1) x d(-1)) for seven days,then both groups were intratracheally challenged with P. Aeruginosa (0.2 ml ATCC 27853 6 x 10(8) CFU/ml). Their blood, bronchial alveolar lavage fluid (BALF) and lung tissue were collected before and 3, 6, 9, 24 h after challenging. Cytological and bacteriological examinations were performed, histopathologic changes of lung tissue were observed. Total proteins (TP) of BALF and the wet/dry ratio (W/D) of lung tissue were determined. RESULTS: (1) Compared with CON group, rats of drug-treated group showed obviously weight loss and thymus atrophy [(141 +/- 8) g] vs [(201 +/- 14) g], [(0.06 +/- 0.05) g] vs (0.40 +/- 0.10) g, P < 0.001], developed leukocytopenia [(0.9 +/- 0.3) x 10(9)/L] vs [(7.3 +/- 1.9) x 10(9)/L, P < 0.001] and the numbers of alveolar macrophage in BALF decreased significantly; (2) After PA challenging, drug-treated rats showed less activities, worse situations and higher mortality (10.8%) than CON group which recovered quickly and none of them died. PA was identified from samples of BALF and lung tissue, both groups developed inflammatory reaction at 6 - 9 h in high level. Pulmonary pathologic study revealed that polymorphonuclears response of drug-treated group was delayed and less serious than that of CON group [at 9 h, drug-treated group, (102 +/- 13)/HP vs CON group (291 +/- 20)/HP, P < 0.01], however, interstitial edema, capillary congestion and focal hemorrhages were more obvious; (3) After PA challenging especially at 6 - 9 h, W/D ratio and TP concentrations were significantly high in both groups than those of before [drug-treated group, W/D (9.2 +/- 1.3) vs (5.9 +/- 1.4) TP (1.59 +/- 0.83) mg/ml vs (0.19 +/- 0.07) mg/ml; CON group:W/D 7.2 +/- 2.5 vs 4.9 +/- 0.8,TP(0.42 +/- 0.16) mg/ml vs (0.13 +/- 0.04) mg/ml, P < 0.05], however the alterations were much greater in drug-treated group (P < 0.05). Alteration of TP concentration showed some correlation with numbers of polymorphonuclears in lung tissue of CON group (r = 0.926, P < 0.05), but not in drug-treated group (r = 0.58, P = 0.31). CONCLUSION: It was indicated that there may be other mechanisms than polymorphonuclears infiltration contributing to the more severe lung injury in drug-treated group characterized as neutropenia.

Animals↗
PubMed2000

Autoradiographic analysis of dopamine receptor-stimulated [(35)S]GTPgammaS binding in rat striatum.

Autoradiographic analysis of [(35)S]GTPgammaS binding was used to investigate functional activation of dopamine receptors in rat striatum. Dopamine-stimulated [(35)S]GTPgammaS binding was observed with a maximal increase of 38% over basal activity. A similar stimulatory response was obtained with the D(2) agonist quinpirole, but not SKF-238393, a D(1) agonist. The effect of dopamine was blocked by the D(2) antagonist raclopride, but was unaffected by SCH-23990, a D(1) antagonist. There appeared to be a differential distribution of dopamine-stimulated [(35)S]GTPgammaS binding, with the lowest activity obtained in the medial portion of the caudal striatum. These results demonstrate, using an autoradiographic approach, (i) that dopamine stimulated [(35)S]GTPgammaS binding in the rat striatum occurs through activation of D(2) receptors, and (ii) that the effects of dopamine activation vary in different areas of the rat striatum.

2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-ben↗
PubMed2000

Association between angiotensin-converting enzyme gene and late onset Alzheimer's disease in Han chinese.

There is now overwhelming evidence that the varepsilon4 allele of apolipoprotein (APOE) gene is a major risk factor for late-onset Alzheimer's disease (AD). However, the APOE locus only accounts for a proportion of the overall genetic risk for AD. The angiotensin-converting enzyme (ACE) is widely expressed in the brain and may have a role in AD. Recently an insertion/deletion (I/D) DNA polymorphism at the intron 16 of ACE gene has been found associated with late-onset AD, but the results are not consistent. We have examined ACE gene in a cohort of Han Chinese AD cases and controls. We have found the ACE-I allele was enriched in our cases compared to controls (odds ratio (OR)=2.09, P=0.0043). The phenomenon was restricted to cases presenting with AD after the age of 70 years (P<0.0005), and was independent of APOE genotype. We conclude that ACE genotype is a risk factor for late onset AD.

Age Factors↗
PubMed2000

Nuclear targeting determinants of the far upstream element binding protein, a c-myc transcription factor.

FUSE binding protein (FBP) binds in vivo and in vitro with the single-stranded far upstream element (FUSE) upstream of the c-myc gene. In addition to its transcriptional role, FBP and its closely related siblings FBP2 (KSRP) and FBP3 have been reported to bind RNA and participate in various steps of RNA processing, transport or catabolism. To perform these diverse functions, FBP must traffic to different nuclear sites. To identify determinants of nuclear localization, full-length FBP or fragments thereof were fused to green fluorescent protein. Fluorescent-FBP localized in the nucleus in three patterns, diffuse, dots and spots. Each pattern was conferred by a distinct nuclear localization signal (NLS): a classical bipartite NLS in the N-terminal and two non-canonical signals, an alpha-helix in the third KH-motif of the nucleic acid binding domain and a tyrosine-rich motif in the C-terminal transcription activation domain. Upon treatment with the transcription inhibitor actinomycin D, FBP completely re-localized into dots, but did not exit from the nucleus. This is in contrast to many general RNA-binding proteins, which shuttle from the nucleus upon treatment with actinomycin D. Furthermore, FBP co-localized with transcription sites and with the general transcription factor TFIIH, but not with the splicing factor SC-35. Taken together, these data reveal complex intranuclear trafficking of FBP and support a transcriptional role for this protein.

Biological Transport↗
PubMed2000

A stereocontrolled, efficient synthetic route to bioactive sphingolipids: synthesis of phytosphingosine and phytoceramides from unsaturated ester precursors via cyclic sulfate intermediates.

An efficient and highly enantioselective method for the preparation of D-ribo- and L-lyxo-phytosphingosines (1a,b, respectively) and phytoceramides (2a,b) has been developed. The key steps in the syntheses are as follows: (i) osmium-catalyzed asymmetric dihydroxylation of 4-O-protected (E)-alpha,beta-unsaturated ester 5 (generated by dihydroxylation of 1-hexadecene, followed by oxidation to the aldehyde and Horner-Wadsworth-Emmons olefination), (ii) conversion to cyclic sulfate intermediate 7, and (iii) regioselective alpha-azidation of 7. Reduction of 4-O-protected 2-azido ester 8 via alpha-azidolactone 9 afforded phytosphingosine 1a. Staudinger reduction of the azido group of 8, followed by in situ N-acylation in aqueous media and reduction of the ester functionality with NaBH(4)/LiBr, provided phytoceramide 2a. By using a similar approach, phytosphingosine 1b was synthesized. D-erythro-4, 5-Dihydrosphingosine 1c and D-erythro-4,5-dihydroceramide 2c were synthesized in high yield from 1-hexadecanol via cyclic sulfate intermediate 15. The desired configurations at C-2, C-3, and C-4 of the sphingoid chain can be accessed readily by the route described here.

Ceramides↗
PubMed2000

Stereoselective preparation of ceramide and its skeleton backbone modified analogues via cyclic thionocarbonate intermediates derived by catalytic asymmetric dihydroxylation of alpha,beta-unsaturated ester precursors.

A novel and efficient synthetic route to ceramide 1a and skeleton backbone modified ceramide analogues 1b,c is reported. The syntheses utilize osmium-catalyzed asymmetric dihydroxylation of (E)-alpha, beta-unsaturated ester 5a-c as the chiral induction step, with the desired configurations in the products 1a-c, 2a, and 13 being generated by regioselective azide substitution at the alpha position of alpha,beta-dihydroxyesters 6a-c via a cyclic thionocarbonate intermediate. Azido esters 10a-c are converted to the corresponding ceramides 1a-c by a sequence of azide reduction, N-acylation, ester reduction (NaBH(4)/LiBr), and Birch reduction of the triple bond (Li, EtNH(2)). These seven- to eight-step syntheses afford the target compounds 1a-c with excellent stereocontrol and in 30-42% overall yields. Furthermore, propargylic alpha-azido-beta-hydroxyester 10a is converted to D-erythro-sphingosine 2a via simultaneous reduction of the triple bond, azido, and ester functional groups with LiAlH(4), providing a highly concise and practical four-step synthesis of this key naturally occurring sphingolipid. The L-erythro stereoisomers are also available in high enantiomeric purity by the method described herein.

Catalysis↗
PubMed2000

Synthesis of ceramide analogues having the C(4)-C(5) bond of the long-chain base as part of an aromatic or heteroaromatic system.

Two efficient and stereoselective methods are described for the preparation of aryl and heteroaryl ceramide analogues 2 and 3. The first route involves the addition of an aryllithium or a heteroaryllithium reagent (7a or 25a, respectively) to the L-serine-derived aldehyde 4, followed by hydrolysis of the oxazolidine, liberation of the amino group, and N-acylation. The second route, which was used to prepare arylceramide analogue 2 in eight steps and 28% overall yield starting with 3-bromobenzaldehyde, utilizes a Heck reaction to afford (E)-alpha,beta-unsaturated ester 16, then osmium-catalyzed asymmetric dihydroxylation for the introduction of the desired chirality at C-2 and C-3. Regioselective alpha-azidation of alpha-O-nosyl-beta-hydroxyester 18 with sodium azide, followed by LiAlH(4) reduction of the azido and ester groups and N-acylation, complete the synthesis of arylceramide analogue 2.

Benzene Derivatives↗
PubMed2000

Surface-enhanced Raman scattering: a structure-specific detection method for capillary electrophoresis.

A new approach to detecting capillary electrophoresis (CE) eluent components by interfacing CE with a surface-enhanced Raman scattering (SERS) system is described. In this approach, CE-based separation of a mixture of trans-1,2-bis(4-pyridyl)ethylene and N,N-dimethyl-4-nitrosoaniline has been detected by SERS in a postcolumn geometry. The retention time obtained from SERS corresponds well with that from conventional UV-visible detection. Meanwhile, CE eluants are identified by their characteristic vibrational spectra, demonstrating the validity of SERS as a structure-specific detection method for CE. In addition, the ability to monitor SERS intensity changes at molecule-specific frequencies makes selective detection of individual analytes possible, even when separation is incomplete. Finally, CE-SERS is evaluated for separation of amino acids (tyrosine and tryptophan) and environmental pollutants (chlorophenol mixtures).

Aniline Compounds↗
PubMed2000

Molecular cloning and characterization of a novel CXC chemokine macrophage inflammatory protein-2 gamma chemoattractant for human neutrophils and dendritic cells.

Chemokines play important roles in leukocyte trafficking as well as function regulation. In this study, we described the identification and characterization of a novel CXC chemokine from a human dendritic cell (DC) cDNA library, the full-length cDNA of which contains an open reading frame encoding 111 aa with a putative signal peptide of 34 aa. This CXC chemokine shares greatest homology with macrophage inflammatory protein (MIP)-2alphabeta, hence is designated as MIP-2gamma. Mouse MIP-2gamma was identified by electrocloning and is highly homologous to human MIP-2gamma. Northern blotting revealed that MIP-2gamma was constitutively and widely expressed in most normal tissues with the greatest expression in kidney, but undetectable in most tumor cell lines except THP-1 cells. In situ hybridization analysis demonstrated that MIP-2gamma was mainly expressed by the epithelium of tubules in the kidney and hepatocytes in the liver. Although no detectable expression was observed in freshly isolated or PMA-treated monocytes, RT-PCR analysis revealed MIP-2gamma expression by monocyte-derived DC. Recombinant MIP-2gamma from 293 cells is about 9.5 kDa in size and specifically detectable by its polyclonal Ab developed by the immunization with its 6His-tagged fusion protein. The eukaryotically expressed MIP-2gamma is a potent chemoattractant for neutrophils, and weaker for DC, but inactive to monocytes, NK cells, and T and B lymphocytes. Receptor binding assays showed that MIP-2gamma does not bind to CXCR2. This implies that DC might contribute to the innate immunity through the production of neutrophil-attracting chemokines and extends the knowledge about the regulation of DC migration.

Adult↗