Biomedical subjects

W Hu

Publications and source records attributed to W Hu.

At least 127 records · Page 7Linked to original sources

PubMed2000

Clinical application of 201Tl SPECT imaging of brain tumors.

UNLABELLED: This study investigated the clinical usefulness of evaluating the histologic grade of brain tumors by 201Tl SPECT brain imaging. METHODS: Early and delayed SPECT brain images were obtained about 10 min and 3 h, respectively, after intravenous injection of 111MBq (3 mCi) 201Tl in 9 healthy subjects (control subjects), 3 patients with brain hematomas, and 41 patients with brain tumors. Semiquantitative data were obtained for early and delayed 201Tl uptake indices and 201Tl retained index in all patients and healthy subjects. RESULTS: In 9 healthy subjects, there was little radioactivity in brain substance. In all patients with brain hematomas or tumors, a high tracer uptake was visible in lesions on early images, but the radioactivity in lesions varied with the histologic nature of the lesion on delayed images. The radioactivity decreased remarkably in brain hematomas (average retained index, 0.61 +/- 0.04). The radioactivity was stable or decreased slightly in benign or low-grade tumors (average retained index, 0.96 +/- 0.24). The radioactivity was increased in high-grade or metastatic tumors (average retained index, 1.26 +/- 0.28). CONCLUSION: This study indicates that 201Tl brain SPECT early and delayed imaging is very useful in brain tumor localization, in distinguishing low-grade from high-grade brain tumors, in predicting histologic grades of brain tumors, and in detecting residual or recurrence of brain tumors postoperatively. 201Tl brain SPECT may also offer the most accurate assessment of response to therapy.

Adult↗

PubMed2000

[Electroporation of sperm to introduce foreign DNA into the genome of Pinctada maxima (Jameson)].

Gene transfer was investigated in marine molluscs via electroporated sperm. Sperm of P. maxima (J.) was incubated with linear "all-fish" growth hormone gene (pCAgcGH and pCAgcGHc) for 30 min. Then, mature eggs were in-vitro fertilized with the sperm cells treated with electroporation at 10 kV and 2(7) pulses of six cycles. DNA was extracted from spat and analyzed by PCR and southern blot. The results indicated that the foreign DNA had been transferred into the genome of experimental molluscs. The transgenetic ration was 5.6%, 20% and 50% when 2 micrograms/mL, 6 micrograms/mL and 18 micrograms/mL of foreign DNA was used, respectively. It is suggested that the transferred efficiency is correlated with the amount of the foreign DNA.

Animals↗

PubMed2000

[Rehabilitation of the first dorsal interosseous muscle by transfer of the extensor pollicis brevis tendon].

Weakness of the pinch grip between index finger and thumb, in ulnar nerve palsy, leads to severe loss of hand function. The first dorsal interosseous plays a major rôle as it abducts and flexes the index finger at its base and stabilizes the MP joint of this finger. Replacement of this muscle is therefore important. The authors report the results of eight clinical cases of replacement of the first dorsal interosseous by extensor pollicis brevis. They obtained good improvement of hand function, in terms of objective and subjective results, in all cases.

Adolescent↗

PubMed2000

Hyperbaric oxygen preconditioning induces neuroprotection against ischemia in transient not permanent middle cerebral artery occlusion rat model.

OBJECTIVE: This study was designed to determine if repeated hyperbaric oxygen (HBO) exposure induces ischemic tolerance in focal cerebral ischemia. METHODS: Sixty male SD rats were used in this study. Thirty animals underwent transient middle cerebral artery occlusion (MCAO) and the other thirty permanent MCAO model. The rats were randomly allocated to 3 sub-groups: control group (n = 10), HBO-3 group (n = 10), and HBO-5 group (n = 10). The animals in HBO-3 and HBO-5 groups received 1 hour hyperbaric oxygenation at 2.5 atmosphere absolute (ATA) in 100% oxygen every day for 3 and 5 days, respectively. The animals in the control group received sham treatments. 24 hours after the last HBO, transient MCAO (120 min) and permanent MCAO were induced by introducing a 3-0 nylon monofilament suture through internal carotid artery based on the Koizumi technique. The neurological outcome was evaluated until 24 hours after reperfusion in transient MCAO rats and ischemia in permanent MCAO rats. The infarct volume was then assessed by TTC staining. RESULTS: In transient MCAO rats, the neurological outcome in both the HBO-3 and HBO-5 groups was better than that of the control group (P < 0.05 and 0.001). The infarct volume decreased from 171.5 +/- 113 mm3 to 40.6 +/- 49.9 mm3(P < 0.05) in the HBO-3 group and 16.2 +/- 28.8 mm3(P < 0.01) in the HBO-5 group. There were no significant differences in neurological outcome and infarct volume among the three groups in permanent MCAO rats. CONCLUSIONS: The present study demonstrated that HBO preconditioning can induce ischemic tolerance in transient not permanent MCAO rats in a "dose-dependent" manner.

Animals↗

PubMed2000

[Shear bond strength of glass ionomer cement for orthodontic bracket bonding].

OBJECTIVE: The purpose of this study was to investigate the shear bond strength of resin-modified glass ionomer used for orthodontic bracket bonding. METHODS: 30 extracted premolars were evenly divided into two groups. Edgewise brackets (Orsu) were bonded with resin-modified glass ionomer (Advance) in group one and with composite resin (DM) in group two. The shear bond strengths of two materials were tested by material testing machine after 24 hours. The adhesive remnant index was scored after debonding. RESULTS: The shear bong strengths of resin-modified glass ionomer and composite resin were (6.862 +/- 2.142) MPa and (7.183 +/- 3.205) MPa respectively. There were no statistically significant differences between two groups. CONCLUSIONS: In vitro bond strength of resin-modified glass ionomer had reached the same level of composite resin. It had the prospect of clinic use.

Composite Resins↗

PubMed2000

[Effects of shuanglong pill on mRNA expression of platelet-derived growth factor A and monocyte chemoattractant protein-1 mRNA].

OBJECTIVE: To explore the molecular mechanism of Shuanglong Pill (SLP) in intervening atherosclerosis, mainly the effect of SLP on the mRNA expression of the platelet-derived growth factor-A (PDGF-A) and the monocyte chemoattractant protein-1 (MCP-1). METHODS: Using the hyperlipoprotein serum (HLS) of cultured rabbits' aortic smooth muscle cell (SMC) to build the atherosclerotic cell model, and medicated serum acting on the cell model by serum pharmacologic method. The effect of SLP medicated serum on the level of PDGF-A, MCP-1 mRNA expression were observed and analysed by means of reverse transcriptase-polymerase chain reaction assay. RESULTS: It was found that HLS stimulated mRNA expression of the PDGF-A and the MCP-1, but the medicated serum of SLP lowered their expression level. CONCLUSION: SLP could inhibit the function of cellular auto-secreting growth factor, it is one of the possible pharmacologic mechanism in intervening atherosclerosis.

Animals↗

PubMed2000

[Changes of myocardial tissue and plasma angiotensin II in rats with pressure overload and effect of lujiao prescription].

OBJECTIVE: To observe the changes of myocardial tissue and plasma angiotensin II in rats with pressure overload and effect of Lujiao prescription (LJP). METHODS: Left ventricular mass index (LVMI), cardiac tissue and plasma angiotensin II were measured in the rat model with myocardial hypertrophy of congestive heart failure and pressure overload by abdominal aortic constriction by radioimmunoassay. RESULTS: LVMI level in the model group was obviously higher than that of the sham group (P < 0.001), while in LJP groups (both groups of low and high dose) was lowered significantly as compared with the model group. The myocardial and plasma angiotensin II levels in the model group were obviously higher than those of the sham group (P < 0.001), while those of the LJP groups were also lowered significantly (P < 0.001). CONCLUSIONS: Cardial tissue and plasma angiotensin II in rats with myocardial hypertrophy of congestive heart failure by pressure overload were increased, and LJP could decrease them significantly. The therapeutic mechanism of LJP in treating heart failure might be related with the lowering of angiotensin II in cardial tissue and plasma so as to reduce the left ventricular hypertrophy.

Angiotensin II↗

PubMed2000

[Attenuation of hyperacute rejection from xenograft by reseeding of endothelial cell].

The potential solution to palliate the critical shortage of suitable donor organs for transplantation may be xenogenic transplantation. However, hyperacute rejection (HAR) after xenotransplantation is the main problem in this process. Since the vascular endothelial cell of donor organ is the primary target cell in rejection, the replacement of endothelium in donor organs with endothelial cell from recipients themselves may be beneficial to the prevention of HAR. Discordant xenotransplantation model (guinea pig-to-rat) was adopted in this study. Firstly, endothelial cell from rat abdominal aorta was separated and cultured. Secondly, the guinea pig abdominal aorta of which the endothelium had been removed was cultured with the suspension containing rat endothelial cells (4 x 10(6)/ml). The viability of cultured vessel was assessed using light microscopy and transmission electron microscopy. The guinea pig vessel reseeded with rat endothelial cell was then examined by immuno-fluorescence staining assay to find out whether IgM and C3 in rat serum were bound to it after preincubation with rat serum. It was found that rat endothelial cells grew into the monolayer endothelium on the inner surface of guinea pig vessel with previous endothelial loss. IgM and C3 in rat serum did not deposit along the new endothelium of guinea pig vessel in the treated group as shown by immuno-fluorescence microscopy, whereas possive results were observed in the untreated normal guinea pig aorta. These findings indicate that donor vessel reseeded with endothelial cell from recipients undergoes less severe rejection and this technique may be very useful for the attenuation of HAR.

Animals↗

PubMed2000

[Isolation and identification of myxobacteria].

This paper reported that the authors isolated large numbers of myxobacteria from more than 100 samples collected in many places of China. More than 400 pure strains were obtained. These strains belonged to 10 genera of Myxococcales. The most frequent genera isolated were Myxococcus, Sorangium, Corallococcus, and Cystobacter. Melittangium was seldom isolated. No Chondromyces and Haploangium were found.

Cellulose↗

PubMed2000

[Effects of high dose of dynorphin on NMDA receptor and NOS activities in spinal cord of rats].

OBJECTIVE: To elucidate the effects of N-methyl-D-aspartate(NMDA) receptor and nitric oxide synthase (NOS) activity in dynorphin (Dyn)-induced spinal cord injury. METHODS: The NMDA receptor activity was measured by radio-ligand of 3H-MK801. The constitutive and inducible NOS (cNOS and iNOS) activities were assayed by 3H-arginine conversion. RESULTS: In ventral samples, both 3H-MK801 binding and cNOS activity increased at 0.5 h and persisted for 48 h while iNOS activity enhanced at 4 h after intratheacal injection (i.t.) Dyn A(1-17) at dose of 20 nmol/L. However, the 3H-MK801 binding activity reduced significantly from 4 h to 24 h and cNOS activity did not change at the same time in dorsal samples. 7-nitroindozol (7-NI) and aminoguanidine (AG) inhibited the effects of Dyn A(1-17) (20 nmol/L) on 3H-MK801 binding and NOS activities in ventral samples. N-nitro-L-arginine methyl ester (L-NAME) did not affect the elevation of Dyn A(1-17) on NOS activities but caused 3H-MK801 binding activity reduction in ventral samples. CONCLUSIONS: NMDA-NOS pathway might play important role in Dyn spinal neurotoxicity. NOS inhibitors and Dyn might produce cooperative down-regulation on the function of NMDA-NOS pathway in dorsal cord.

Animals↗

PubMed2000

[Application of confocal microprobe Raman spectroscopy in the analysis of interfaces].

Confocal microprobe Raman spectroscopy has been applied to the study of liquid/gas and solid/liquid interfaces. With the help of the resonance Raman effect, the aggregation process of TSPP has been monitored at the liquid/gas interface using Raman spectroscopy, which is shown to have very different behavior compared with that in the bulk. The solution layer analysis has been performed in the interfacial region above a Pt electrode under reaction, and the solution composition is monitored in situ during the electrochemecial reaction. Taking the advantage of high spatial resolution of the confocal microscope, the surface enhanced Raman imaging has been performed on the electrodeposited gold surface.

Electrochemistry↗

PubMed1999

Anchoring an extended HTLV-1 Rex peptide within an RNA major groove containing junctional base triples.

BACKGROUND: The Rex protein of the human T cell leukemia virus type 1 (HTLV-1) belongs to a family of proteins that use arginine-rich motifs (ARMs) to recognize their RNA targets. Previously, an in vitro selected RNA aptamer sequence was identified that mediates mRNA transport in vivo when placed in the primary binding site on stem-loop IID of the Rex response element. We present the solution structure of the HTLV-1 arginine-rich Rex peptide bound to its RNA aptamer target determined by multidimensional heteronuclear NMR spectroscopy. RESULTS: The Rex peptide in a predominantly extended conformation threads through a channel formed by the shallow and widened RNA major groove and a looped out guanine. The RNA aptamer contains three stems separated by a pair of two-base bulges, and adopts an unanticipated fold in which both junctional sites are anchored through base triple formation. Binding specificity is associated with intermolecular hydrogen bonding between guanidinium groups of three non-adjacent arginines and the guanine base edges of three adjacent G.C pairs. CONCLUSIONS: The extended S-shaped conformation of the Rex peptide, together with previous demonstrations of a beta-hairpin conformation for the bovine immunodeficiency virus (BIV) Tat peptide and an alpha-helical conformation for the human immunodeficiency virus (HIV) Rev peptide in complex with their respective RNA targets, expands our understanding of the strategies employed by ARMs for adaptive recognition and highlights the importance of RNA tertiary structure in accommodating minimalist elements of protein secondary structure.

Amino Acid Sequence↗

PubMed1999

Plant importin alpha binds nuclear localization sequences with high affinity and can mediate nuclear import independent of importin beta.

Nuclear import of conventional nuclear localization sequence (NLS)-containing proteins initially involves recognition by the importin (IMP) alpha/beta heterodimer, where IMPalpha binds the NLS and IMPbeta targets the IMPalpha/NLS-containing protein complex to the nuclear pore. Here we examine IMPalpha from the plant Arabidopsis thaliana (At-IMPalpha), which exhibits nuclear envelope localization typical of IMPbeta rather than IMPalpha in other eukaryotic cell systems. We show that At-IMPalpha recognizes conventional NLSs of two different types with high affinity (K(d) of 5-10 nM), in contrast to mouse IMPalpha (m-IMPalpha), which exhibits much lower affinity (K(d) of 50-70 nM) and only achieves high affinity in the presence of m-IMPbeta. Unlike m-IMPalpha, At-IMPalpha is thus a high affinity NLS receptor in the absence of IMPbeta. Interestingly, At-IMPalpha was also able to bind with high affinity to NLSs recognized specifically by m-IMPbeta and not m-IMPalpha, including that of the maize transcription factor Opaque-2. Reconstitution of nuclear import in vitro indicated that in the absence of exogenous IMPbeta subunit but dependent on RanGDP and NTF2, At-IMPalpha was able to mediate nuclear accumulation to levels comparable with those mediated by m-IMPalpha/beta. Neither m-IMPalpha nor -beta was able to mediate nuclear import in the absence of the other subunit. At-IMPalpha's novel NLS recognition and nuclear transport properties imply that plants may possess an IMPalpha-mediated nuclear import pathway independent of IMPbeta in addition to that mediated by IMPalpha/beta.

Amino Acid Sequence↗

PubMed1999

Secondary structure and fold homology of the ArsC protein from the Escherichia coli arsenic resistance plasmid R773.

Resistance to several toxic anions in Escherichia coli is conferred by the ars operon carried on plasmid R773. The gene products of this operon catalyze extrusion of antimonials and arsenicals from cells. In this paper, we report the determination of the overall fold for ArsC, a 16 kDa protein of the ars operon involved in the reduction of arsenate to arsenite, using multidimensional, multinuclear NMR. The protein is found to contain large regions of extensive mobility, particularly in the active site. A model fold, computed on the basis of a preliminary set of NOEs, was found to be structurally homologous to E. coli glutaredoxin, thiol transferases, and glutathione S-transferase. Some kinship to the structure of low molecular weight tyrosine phosphatases, based on rough topological similarity but more so on the basis of a common anion-binding-loop motif H-CX(n)R, was also detected. Although functional, secondary, and tertiary structural homology is observed with these molecules, no significant homology in primary structure was detected. The mobilities of the active site of ArsC and of other enzymes are discussed.

Adenosine Triphosphatases↗

PubMed1999

Separation of carboxylic acids on a weakly acidic cation-exchange resin by ion-exclusion chromatography.

The separation of various carboxylic acids was performed on a polymethacrylate-based weakly acidic cation-exchange resin (TSKgel OApak-A) using ion-exclusion chromatography under the acidic elution conditions. When a diluted sulfuric acid solution was used as the eluent, highly sensitive conductimetric detection of carboxylic acids was achieved without increasing the background conductance of the eluent. This method was more sensitive than using benzoic acid eluent and enabled a good resolution of dicarboxylic as well as monocarboxylic acids. The addition of 5-20% methanol to the eluent considerably reduced the retention times of carboxylic acids with hydrophobic nature.

Carboxylic Acids↗

PubMed1999

Electrostatic ion chromatography of polarizable anions in saline waters with N-[2-[acetyl(3-sulfopropyl)amino]ethyl]-N,N-dimethyldodecanaminium hydroxide (ammonium sulfobetaine-1) as the stationary phase and a dilute electrolytic solution as the mobile phase.

A new type of zwitterionic surfactant, N-{2-[acetyl(3-sulfopropyl)amino]ethyl}-N,N-dimethyldodecanaminium hydroxide (ammonium sulfobetaine-1), with a greater distance between the two charged groups, was used as the stationary phase for electrostatic ion chromatography (EIC) of polarizable anions (e.g., thiocyanate, iodide and nitrate) in saline water samples. The targeted species (polarizable anions) were baseline separated using this type of zwitterionic surfactant as the stationary phase, but the highly polarizable species (iodide and thiocyanate) were eluted faster (compared with the results obtained using N-dodecyl-N,N-dimethyl-3-ammonio-1-propanesulfonate, C12N3S, with a shorter distance between the two charged groups, as the stationary phase). In other words, the extent of binding of the highly polarizable anion (iodide and thiocyanate) was found to be smaller when using ammonium sulfobetaine-1 as the stationary phase. This provides a rapid but effective method for the analysis of highly polarizable anions in saline water samples. The results for the successful detection of iodide in seawater demonstrates the usefulness of this new type of zwitterionic surfactants for EIC.

Betaine↗

PubMed1999

Saccharide-RNA recognition in a complex formed between neomycin B and an RNA aptamer.

BACKGROUND: Aminoglycoside antibiotics can target RNA folds with micromolar affinity and inhibit biological processes ranging from protein biosynthesis to ribozyme action and viral replication. Specific features of aminoglycoside antibiotic-RNA recognition have been probed using chemical, biochemical, spectroscopic and computational approaches on both natural RNA targets and RNA aptamers identified through in vitro selection. Our previous studies on tobramycin-RNA aptamer complexes are extended to neomycin B bound to its selected RNA aptamer with 100 nM affinity. RESULTS: The neamine moiety (rings I and II) of neomycin B is sandwiched between the major groove floor of a 'zippered-up' G.U mismatch aligned segment and a looped-out purine base that flaps over the bound antibiotic. Specific intermolecular hydrogen bonds are observed between the charged amines of neomycin B and base mismatch edges and backbone phosphates. These interactions anchor 2-deoxystreptamine ring I and pyranose ring II within the RNA-binding pocket. CONCLUSIONS: The RNA aptamer complexes with tobramycin and neomycin B utilize common architectural principles to generate RNA-binding pockets for the bound aminoglycoside antibiotics. In each case, the 2-deoxystreptamine ring I and an attached pyranose ring are encapsulated within the major groove binding pocket, which is lined with mismatch pairs. The bound antibiotic within the pocket is capped over by a looped-out base and anchored in place through intermolecular hydrogen bonds involving charged amine groups of the antibiotic.

Anti-Bacterial Agents↗

PubMed1999

Five-transmembrane domains appear sufficient for a G protein-coupled receptor: functional five-transmembrane domain chemokine receptors.

The putative seven-transmembrane (TM) domains have been the structural hallmark for the superfamily of heterotrimeric G protein-coupled receptors (GPCRs) that regulate a variety of cellular functions by mediating a large number of extracellular signals. Five-TM GPCR mutants of chemokine receptor CCR5 and CXCR4, the N-terminal segment of which connected directly to TM3 as a result of a deletion of TM1-2 and the first intracellular and extracellular loops, have been obtained in this study. Laser confocal microscopy and flow cytometry analysis revealed that these five-TM mutant GPCRs were expressed stably on the cell surface after transfection into human embryonic kidney 293 cells. The five-TM CCR5 and CXCR4 functioned as normal chemokine receptors in mediating chemokine-stimulated chemotaxis, Ca2+ influx, and activation of pertussis toxin-sensitive G proteins. Like the wild-type GPCRs, the five-TM mutant receptors also underwent agonist-dependent internalization and desensitization and were subjected to regulation by GPCR kinases and arrestins. Our study indicates that five-TM domains, at least in the case of CCR5 and CXCR4, appear to meet the minimum structural requirements for a functional GPCR and suggests possible existence of functional five-TM GPCRs in nature during evolution.

1-Methyl-3-isobutylxanthine↗