Biomedical subjects

J Xu

Publications and source records attributed to J Xu.

At least 397 records · Page 22Linked to original sources

PubMed2000

Protective effect of Oren-gedoku-to (Huang-Lian-Jie-Du-Tang) against impairment of learning and memory induced by transient cerebral ischemia in mice.

The protective effect of Oren-gedoku-to (OGT; Huang-Lian-Jie-Du-Tang), a traditional Chinese medicine, against impairment of learning and memory induced by transient cerebral ischemia was investigated in mice. The cerebral ischemia caused a reduction of step-down latency and an increase of step-down errors in the passive avoidance task. Pretreatment with oral administration of OGT (2, 4 or 8 g of herbs per kg) once daily for 5 days prolonged the step-down latency significantly and decreased the step-down errors as compared with those of sham-operated controls. In the Morris water maze test, the cerebral ischemia caused an increase in the latency until finding the platform in the training trial and a decrease in the percentage of swimming in the quadrant of the former platform in the probe trial. Oren-gedoku-to (OGT; 2, 4 and 8 g/kg, p. o.) shortened the latency of escaping markedly onto the platform in the training trial and increased the percentage of crossing the former platform quadrant in the probe trial. A reference drug, tacrine (0.5 and 1.0 mg/kg, p.o.), prevented the reduction of step-down latency in the passive avoidance task and shortened the escape latency in the Morris water maze task. Furthermore, OGT significantly protected against cerebral ischemia-induced reduction in the acetylcholine (ACh) content of the cerebral cortex, hippocampus and striatum. These results indicate that the protective effects of OGT against the impairment of learning and memory induced by transient cerebral ischemia may be associated with preventing the decrease in the ACh content of the mouse brain.

Acetylcholine↗

PubMed2000

Effect of Ar ion irradiation on electrochemical behaviors of zircaloy-4

In order to investigate the effect of the damage on the electrochemical behavior, zircaloy-4 specimens were irradiated by Ar ions using an accelerator at an energy of 50 keV, with doses from 3 x 10(14) to 3 x 10(16) ions/cm2 at liquid nitrogen temperature. Potentiodynamic polarization measurements were employed to evaluate the corrosion resistance of zircaloy-4 in a 0.5 M H2SO4 water solution at room temperature. A damage efficiency function on the passive current density of the polarization curve was defined and deduced theoretically.

Journal Article↗

PubMed2000

Humoral immune response to proteins of human cytomegalovirus latency-associated transcripts.

Latent human cytomegalovirus (CMV) infection of hematopoietic progenitor cells is associated with the presence of latency-associated transcripts that may express 6 proteins larger than 44 amino acids in size (open reading frame [ORF] 55, ORF45, ORF94, ORF59, ORF154, ORF152/UL124). The serologic response to these proteins was evaluated in healthy seropositive individuals as well as in individuals undergoing active CMV infection. Individual recombinant GST-fusion proteins, prepared from bacteria, were found by enzyme-linked immunosorbent assay to be recognized by between 8% and 44% long-term healthy seropositive individuals, with ORF94 and ORF55 being the most broadly and significantly recognized. Although nearly all of serum samples (85%) recognized at least 1 of these proteins, none reacted with all 6. Patterns of antibody prevalence to these proteins in long-term seropositive individuals were similar to many antigens expressed during productive replication (IE1, ppUL57, ppUL83/pp65), but none were broadly detected by a majority of individuals, a characteristic of only a few productive-phase antigens, including ppUL44/ICP36 and ppUL32/pp150. Consistent with prevalence in long-term seropositive individuals, commercial preparations of pooled human gamma globulin were also found to recognize latency-associated proteins. Serologic reactivity to latency-associated proteins was slow to develop following primary infection, in a pattern distinct from any of the characterized replication-phase proteins tested here, and was boosted late after secondary infection or reactivation in solid-organ transplant recipients without showing a correlation with viremia or disease. These results provide evidence that proteins expressed from the latent region during natural infection exhibit immunogenicity comparable with most other characterized viral antigens, although the narrow response to individual latency-associated proteins likely precludes their use in serologic assays to investigate clinical correlates or outcome in transplant recipients.

Antibodies, Viral↗

PubMed2000

Substrate effects of gel surfaces on cell adhesion and disruption.

Substrate effects of hydrogel surfaces prepared on hydrophilic and hydrophobic substrates on the cell adhesion and disruption were studied. The adhesion of tobacco protoplasts onto anionic hydrogels was strongly influenced by the substrates on which the gels were synthesized. In the case of anionic poly(2-acrylamido-2-methylpropanesulfonic acid) gel, more cells adhered on the gel surface prepared on hydrophobic substrates than that prepared on hydrophilic substrates. On the other hand, in the case of cationic quaternized poly-(dimethylaminopropylacrylamide) gel, cell disruption occurred in a few seconds accompanied with an intensive release of cellular contents on the gel surface prepared on the hydrophilic substrates, while the cationic gel synthesized on hydrophobic substrates induced no cell disruption. These different behaviors of the cell have been made in terms of different structures of gel surfaces associated with the presence of flexible dangling chains.

Acrylamides↗

PubMed2000

Four new clerodane diterpenoids from Callicarpa pentandra.

Leaf extracts of Callicarpa pentandra provided four new clerodane-type diterpenoids (1-4), of which 1, 2, and 4 have ring-A-contracted structures. Their structures and stereochemistry were established by spectral data interpretation, and for 3 also by single-crystal X-ray diffraction.

Chromatography, Liquid↗

PubMed2000

Influence of chemically modified tetracyclines on proliferation, invasion and migration properties of MDA-MB-468 human breast cancer cells.

Chemically modified tetracyclines (CMTs) are promising anti-cancer agents. In this study, we found that CMT-3 and CMT-8 showed dose-dependent cytotoxicities in MDA-MB-468 human breast cancer cells. Moreover, both CMT-3 and CMT-8 significantly inhibited in vitro cell migration and invasion at non-cytotoxic concentrations. Anti-invasion and migration potentials of the CMTs were associated with an increased expression of E-cadherin/catenins (alpha, beta and gamma-catenin) and tumor suppressor BRCA1. In addition, CMT-3 and CMT-8 abolished or reduced spontaneous and HGF/SF-induced cell invasion and migration in U-373 MG human glioblastoma cells. Our current finding is the first demonstration that CMT-3 and CMT-8 can activate the function of invasion suppressor molecules associated with the suppression of breast cancer cell invasion and migration. Thus, clinical application of CMTs may provide potential benefit for suppression of breast cancer growth, invasion and metastasis.

Antineoplastic Agents↗

PubMed2000

Permeability and diffusion in vitreous humor: implications for drug delivery.

PURPOSE: Previous experimental work suggests that convection may be important in determining the biodistribution of drugs implanted or injected in the vitreous humor. To develop accurate biodistribution models, the relative importance of diffusion and convection in intravitreal transport must be assessed. This requires knowledge of both the diffusivity of candidate drugs and the hydraulic conductivity of the vitreous humor. METHODS: Hydraulic conductivity of cadaveric bovine vitreous humor was measured by confined compression tests at constant loads of 0.15 and 0.2 N and analyzed numerically using a two-phase model. Diffusion coefficient of acid orange 8, a model compound, in the same medium was measured in a custom-built diffusion cell. RESULTS: Acid orange 8 diffusivity within vitreous humor is about half that in free solution. When viscous effects are properly accounted for, the hydraulic conductivity of bovine vitreous humor is 8.4+/-4.5 x 10(-7) cm2/Pa x s. CONCLUSIONS: We predict that convection does not contribute significantly to transport in the mouse eye, particularly for low-molecular-weight compounds. For delivery to larger animals, such as humans we conclude that convection accounts for roughly 30% of the total intravitreal drug transport. This effect should be magnified for higher-molecular-weight compounds, which diffuse more slowly, and in glaucoma, which involves higher intraocular pressure and thus potentially faster convective flow. Thus, caution should be exercised in the extrapolation of small-animal-model biodistribution data to human scale.

Animals↗

PubMed2000

Normal telomere lengths found in cloned cattle.

Success of cloning using adult somatic cells has been reported in sheep, mice and cattle. The report that 'Dolly' the sheep, the first clone from an adult mammal, inherited shortened telomeres from her cell donor and that her telomeres were further shortened by the brief culture of donor cells has raised serious scientific and public concerns about the 'genetic age' and potential developmental problems of cloned animals. This observation was challenged by a recent report that showed calves cloned from fetal cells have longer telomeres than their age-matched controls. The question remains whether Dolly's short telomeres were an exception or a general fact, which would differ from the telomeres of fetal-derived clones.

Aging↗

PubMed2000

Photoelectron spectroscopy of ammonia via a fast predissociative state

We report a study on resonance enhanced multiphoton ionization photoelectron spectroscopy (REMPI-PES) involving the fast predissociative A state of ammonia, using nano- and femtosecond lasers. The multiphoton scheme involves (1 + 1), (2 + 2), (2 + 2) + 1 and (2 + 2) + 2 photon processes. We have found a progression of stretching vibrations v1 in the PE spectrum when pumping NH3 A v2 = 0, 1 and 3 as intermediate states. The stretching vibration intensity distributions in the photoelectron spectrum are calculated by using the Chebychev method of the wavepacket propagation. The femtosecond spectrum shows a similar feature to the nanosecond spectrum. However, high laser power also causes band broadening and shifting effect as well as above threshold multiphoton ionization.

Journal Article↗

PubMed2000

Multiple gene genealogies reveal recent dispersion and hybridization in the human pathogenic fungus Cryptococcus neoformans.

Cryptococcus neoformans (= Filobasidiella neoformans) is a significant emerging fungal pathogen of humans. To understand the evolution of this pathogen, 34 strains were obtained from various locations around the world and fragments of four genes were sequenced from each. These strains represented all three varieties and five serotypes. The four sequenced genes are: (i) the mitochondrial large ribosomal subunit RNA; (ii) the internal transcribed spacer region of the nuclear rRNA, including ITS1, 5.8S rRNA subunit and ITS2; (iii) orotidine monophosphate pyrophosphorylase; and (iv) diphenol oxidase. Phylogenetic analyses indicated considerable divergence among lineages, which corresponded to the current classification of C. neoformans into three varieties. However, there is no apparent phylogeographic pattern. Significant incongruences were observed among gene genealogies. The analyses indicated that the major lineages in C. neoformans diverged tens of millions of years ago but have undergone recent dispersion and hybridization.

Catechol Oxidase↗

PubMed2000

Gene expression of vascular endothelial growth factor in giant cell tumors of bone.

The production of vascular endothelial growth factors (VEGF), a major cause of neoangiogenesis, is a prerequisite for tumor growth and invasion. VEGF have also been shown to be important for the formation of osteoclasts. Because giant cell tumors of bone (GCT) are frequently hypervascular and have the ability to recruit macrophages and multinucleated osteoclast-like giant cells, we evaluated the levels of VEGF gene transcript in several of these tumors using Northern blot analyses, semiquantitative reverse transcription polymerase chain reaction (RT-PCR), fluorescence in situ hybridization (FISH), and immunohistochemistry. Our results showed that three major isoforms of VEGF (121, 165, and 189) were expressed in all cases of GCT investigated, with isoform 121 transcripts the most abundant. By both FISH and immunohistochemistry, we have shown that VEGF was present in spindle-shaped stromal-like tumor cells, round macrophage-like cells, and osteoclast-like multinucleate giant cells. Moreover, we have shown that the levels of VEGF gene expression but not microvessel density correlated with Enneking's clinical stage of GCT. There were higher levels of VEGF gene expression in stage III GCT than in stage I/II GCT (P < .0357). In conclusion, our results indicate that overexpression of VEGF may be associated with the advanced stage of the neoplasm.

Adult↗

PubMed2000

The effect of wrapping scarred nerves with autogenous vein graft to treat recurrent chronic nerve compression.

The purpose of this study was to determine the efficacy of vein wrapping of scarred nerves in a chronic nerve compression model in rats. The ultimate goal was to provide experimental evidence for application of the technique of vein wrapping of nerves for the treatment of recurrent compressive neuropathy. The chronic nerve compression model was created in 100 rats. After 8 months the nerves were decompressed. In 50 rats the nerves were wrapped with an opened femoral vein graft; the remaining 50 animals served as controls. The sciatic nerves of both groups were evaluated at 4, 8, 12, 24, and 48 weeks after surgery. Functionally, the sciatic nerves in the vein-wrapped group showed greater improvement than those in the non-vein-wrapped group. For electrophysiologic testing the latency was significantly shorter in the vein-wrapped group. Histologic evaluation showed marked nerve degeneration and scar tissue formation around the nerves in the non-vein-wrapped group but not in the vein-wrapped group. The results indicate that the vein graft could improve the recovery of nerve function by protecting the nerve from surrounding scar and is an effective and feasible technique for the surgical treatment of recurrent compressive neuropathy. (J Hand Surg 2000; 25A:93-103.

Action Potentials↗

PubMed2000

Correction of severe congenital epicanthus using the modified square-flap method.

The square-flap method has been gradually adopted for the correction of cicatricial contracture because it effectively relieves the longitudinal shortness in the deformity. Since 1990, the authors have slightly modified the design and employed it for the correction of severe congenital epicanthus. Forty-six cases (23 patients) have been treated by using this modified square flap. Good functional and cosmetic results were obtained. The authors consider it an effective technique with the advantages of rational design, simple operation and fewer incisions. This paper describes the operation design and discusses the advantages and key points of the surgery.

Adolescent↗

PubMed2000

Vascularized plantaris tendon graft: anatomic study of the donor.

In order to determine new vascularized donor tendons for grafting, a detailed anatomic study of the plantaris tendon and vascular connections with the posterior tibial artery or its branches was undertaken in 20 legs of 10 fresh adult cadavers. A histologic evaluation was also undertaken. Findings demonstrated that there is a close vascular connection between the crural fascial-linked section of the plantaris tendon and the posterior tibial artery. Through its rich surrounding paratenon, the blood supply of the tendon is provided by two to four transfascial branches of the posterior artery in the lower-middle portion of the leg. Out of these branches, one or two anastomosing arteries (more than 1.0 mm in diameter), together with accompanying veins, consistently emerge 5 to 8 cm from the insertion of the plantaris tendon. Histologic observations demonstrate the reliable vascularity of the paratenon and crural fascia. The authors consider this vascularized tendon donor a good option for grafting. A composite tendofascial flap with vascularized pedicle from the posterior tibial artery or an isolated vascularized tendon graft from its branches would both be alternative techniques for clinical vascularized tendon grafting.

Adult↗

PubMed2000

Different methods and results in the treatment of obstetrical brachial plexus palsy.

Mallet's test was used to evaluate shoulder and elbow functional results following conservative treatment, neurolysis, and nerve transfer and grafting in 31 patients with obstetrical brachial plexus palsy, who had no recovery of biceps contraction by 3 months of age. Twelve of them had been treated conservatively for 3 to 4 years. Nine patients with upper trunk conducting neuromas underwent neurolysis at the age of 4 to 6 months. Nerve transfer and grafting were performed in 10 patients at the age of 3 to 6 months. Upper trunk conducting neuromas were found in six of them. The follow-up period was, on average, 44.3 and 51.5 months in the nerve transfer and grafting group and in the neurolysis group, respectively. Excellent and good results in shoulder abduction, external rotation, and elbow flexion were found in 70 percent of patients in the nerve transfer and grafting group. However, none of the conservative treatment and neurolysis groups had a good result. The authors conclude that when there is no recovery of biceps contraction by 3 months of age, surgical intervention is indicated. Neuroma should be managed by nerve transfer and grafting, even though intraoperative electrophysiologic studies show that the neuroma is a conducting one.

Brachial Plexus Neuropathies↗

PubMed2000

Absorption, distribution, metabolism and excretion of p-bromophenylacetylurea in the female rat.

1. This study has investigated absorption, distribution, metabolism and excretion of p-bromophenylacetylurea (BPAU) in the F344 female rat. BPAU and its metabolites were determined by HPLC. 2. Following a single p.o. dose of 150 mg/kg BPAU, the absorbed fraction of dosed BPAU was 65.9% and its half-life in the blood was 9.4 h. The relative distribution of BPAU (tissue/serum ratio) at 6 h (peak time point) after a single i.p. dose of 150 mg/kg BPAU was spinal cord (4.6+/-0.2) > liver (3.7+/-0.1) > brain (2.9+/-0.1) (mean+/-SD, n = 5), and they were significantly different from each other (p < 0.05). BPAU in spinal cord reached the highest level. 3. Absorbed BPAU was metabolized in vivo into three major metabolites. N'-hydroxy-p-bromophenylacetylurea (M1) was a dominant metabolite in tissues, whereas 4-(4-bromophenyl)-3-oxapyrrolidine-2,5-dione (M2) reached a high concentration in blood. N'-methyl-p-bromophenylacetylurea (M3) was mainly found in the urine. All three metabolites were excreted via the urine and together accounted for 87% of absorbed BPAU. 4. This study provides a basic understanding of BPAU absorption, distribution, metabolism and elimination in rat.

Administration, Oral↗

PubMed2000

Multidentate hydroxypyridinonate ligands for Pu(IV) chelation in vivo: comparative efficacy and toxicity in mouse of ligands containing 1,2-HOPO or Me-3,2-HOPO.

PURPOSE: To identify the most effective multidentate 1,2-HOPO and Me-3,2-HOPO ligands for chelation of Pu(IV) in vivo. MATERIALS AND METHODS: Two sets of ligands with four identical backbones were prepared containing two, three or four bidentate 1,2-HOPO or Me-3,2-HOPO groups, and 3,4,3-LI(1,2-HOPO) was resynthesized in a higher yielding procedure. They were evaluated in mouse for acute toxicity and reduction of tissue 238Pu, in comparison with CaNa3-DTPA (30 micromol kg(-1)). RESULTS: Nine HOPO ligands, promptly injected or given orally or injected at low dosage, are superior to CaNa3-DTPA for reducing 238Pu retention in mouse. Five, given by delayed injection or promptly injected or orally administered as ferric complexes, are superior to CaNa3-DTPA or FeNa2-DTPA respectively. The Me-3,2-HOPO ligands are more effective than their structural 1,2-HOPO analogues, demonstrating the greater affinity of Me-3,2-HOPO for Pu(IV) in vivo. CONCLUSIONS: The most efficacious ligand, 3,4,3-LI(1,2-HOPO), contains the less stably binding 1,2-HOPO group; therefore, its linear spermine backbone must confer advantages for Pu(IV) binding (greater solubility, more favorable arrangement of ligating groups, more flexible backbone). Effective low toxicity tetradentate 5-LIO(Me-3,2-HOPO) and hexadentate TREN-(Me-3,2-HOPO) and highly effective but moderately toxic 3,4,3-LI(1,2-HOPO) (LD50 approximately 300 micromol kg(-1) in mouse) are recommended for further investigation.

Administration, Oral↗

PubMed2000

Full-genome scan for linkage in 50 families segregating the bipolar affective disease phenotype.

A genome scan of approximately 12-cM initial resolution was done on 50 of a set of 51 carefully ascertained unilineal multiplex families segregating the bipolar affective disorder phenotype. In addition to standard multipoint linkage analysis methods, a simultaneous-search algorithm was applied in an attempt to surmount the problem of genetic heterogeneity. The results revealed no linkage across the genome. The results exclude monogenic models and make it unlikely that two genes account for the disease in this sample. These results support the conclusion that at least several hundred kindreds will be required in order to establish linkage of susceptibility loci to bipolar disorder in heterogeneous populations.

Bipolar Disorder↗