Biomedical subjects

W Wu

Publications and source records attributed to W Wu.

At least 91 records · Page 5Linked to original sources

PubMed2001

[The pathology and DNA quantitative study of renal clear cell carcinoma in children].

OBJECTIVE: To investigate the pathological features of renal clear cell carcinoma (RCCC) in children and its relationship to the DNA content of cancer cells and DNA ploidy. METHODS: The pathologic morphology of 4 cases of RCCC in children were observed. Using image analysis instruments the quantity of tumor cell DNA was measured. RESULTS: The cytoplasm of the tumor cells were clear in all four cases. Papillary structures were present in these tumors, of which the papillary structure in two cases was over 50%, three cases had small calcified bodies with prominent bleeding and necrosis. Around tumor the glomerular and tubular of kidney always is normal the average DNA index was 1.31. They presented diploidy, high diploidy or subtetraploidy. CONCLUSIONS: The specific features of most RCCC in children are clear cytoplasm, most contain papillary structures, calcified bodies, often with bleeding and necrosis. Around tumor the glomerular and tubular of kidney is always normal. The DNA contents of cancer cells present diploidy, high diploidy or subtetraploidy.

Carcinoma, Renal Cell↗

PubMed2001

[Xu Shou and the provenance of "confluence of Chinese and western medicine"].

Formerly, it is generally recognized that the idea of "confluence of Chinese and western medicine" was originated from Li Hongzhang's preface to the book, Wan guo yao fang (International Prescriptions) in 1890. Based on my own materials, in 1876, Xu Shou's Yi xue lun (On Medicine) already mentioned this term which may be reckoned as its earliest record.

Books↗

PubMed2001

[Long-term efficacy of vaccination against hepatitis B in newborns: 13 years' follow-up].

OBJECTIVE: To evaluate long-term efficacy of hepatitis B vaccination in newborns. METHODS: In the past 13 years we followed up the children who had been immunized with hepatitis B vaccine at birth in 1986 every other year. At each follow-up visit, every child was tested for HBsAg, anti-HBs and anti-HBc. RESULTS: HBsAg positive rate of these birth cohort was low (range between 0.46% and 0.98%) during 13 years' follow-up. Long-term efficacy of the vaccination in preventing HBsAg carriage was confirmed. CONCLUSIONS: Thirteen years later no booster was after needed.

Female↗

PubMed2001

Effect of batroxobin on expression of neural cell adhesion molecule in temporal infarction rats and spatial learning and memory disorder.

The effect of Batroxobin expression of neural cell adhesion molecule (NCAM) in left temporal ischemic rats with spatial memory disorder was investigated by means of Morri's water maze and immunohistochemical methods. The results showed that the mean reaction time and distance of temporal ischemic rats for searching a goal were significantly longer than those of sham-operated rats and at the same time NCAM expression of left temporal ischemic region was significantly increased. However, the mean reaction time and distance of Batroxobin-treated rats were shorter and they used normal strategies more often and earlier than those of ischemic rats. The number of NCAM immune reactive cells of Batroxobin-treated rats was more than that of ischemic group. In conclusion, Batroxobin can improve spatial memory disorder of temporal ischemic rats and the regulation of the expression of NCAM is probably related to the neuroprotective mechanism.

Animals↗

PubMed2001

[Intravitreally injectable poly (D, L-Lactide) microspheres containing dexamethasone acetate for sustained release].

AIM: To prepare and evaluate dexamethasone acetate-loaded poly (d, l-lactide) microspheres for sustained release in vitro and their therapeutic effect on proliferative vitreoretinopathy in vivo. METHODS: The microspheres were prepared by a solvent evaporation/extraction technique. Properties such as geometric mean diameter, span, drug loading, rate of entrapment and release characteristics were evaluated. Differential scanning calorimetry and X-ray powder diffractometry were used to identify the physical phase of dexamethasone acetate in poly (d, l-lactide) matrix, and safety in vivo was examined. Effect of drug-loaded microspheres on suppression of experimental proliferative vitreoretinopathy was studied in albino rabbit eyes after an intravitreal injection of macrophages. RESULTS: The geometric mean diameter and span of the microspheres were 62.9 microns and 0.92, respectively. Drug loading and rate of entrapment of dexamethasone acetate in microspheres were 17.5% and 86.5%, respectively. Differential scanning calorimetry and X-ray powder diffractometry showed that dexamethasone acetate dispersed uniformly as molecules in poly (d, l-lactide) matrix. Ninety percent of the dexamethasone acetate was released in vitro from dexamethasone acetate after 48 days, while the same amount released from microspheres took 90 days. Storage under 4 degrees C in refrigerator or 25 degrees C in a dessicator at a relative humidity of 75% for 90 days had little effect on the properties of the microspheres. Intravitreal injection of microspheres showed a sustained release and continuous action of dexamethasone acetate for 84 days. After injection of activated macrophages, the groups of blank microspheres and dexamethasone acetate showed proliferation to different extent, while the base of the eye remained clear and no obvious proliferation was observed for the group of microspheres. A significant difference exists between these three groups. CONCLUSION: Poly (d, l-lactide) microspheres containing dexamethasone acetate is a potentially promising delivery system for the suppression of proliferative vitreoretinopathy.

Animals↗

PubMed2000

Expression of constitutively active phosphatidylinositol 3-kinase inhibits activation of caspase 3 and apoptosis of cardiac muscle cells.

Apoptosis of cardiac muscle cells contributes to the development of cardiomyopathy. Recent studies showed that insulin-like growth factor I (IGF-I) inhibits apoptosis of cardiac muscle cells and improves myocardial function in experimental heart failure. This study was carried out to elucidate the role of phosphatidylinositol 3-kinase (PI 3-kinase) in the anti-apoptotic actions of IGF-I in cardiomyocytes and to explore whether expression of constitutively active PI 3-kinase can inhibit apoptosis in cardiomyocytes. Apoptosis of primary cardiomyocytes was induced by doxorubicin treatment and serum withdrawal. Transduction of cardiomyocytes with constitutively active PI 3-kinase specifically lead to serine phosphorylation of Akt, whereas phosphorylation of IGF-I receptor, IRS1/2 and p44/42 mitogen-activated protein kinase were not increased. In the cardiomyocytes transduced with constitutively active PI 3-kinase, activation of the pro-apoptotic caspase 3 was attenuated and fragmentation of DNA was reduced. Preincubating cells with PI 3-kinase inhibitor LY294002 was associated with loss of anti-apoptotic actions of IGF-I and PI 3-kinase. Neither IGF-I nor constitutively active PI 3-kinase lead to serine phosphorylation of Bad, suggesting that the anti-apoptotic effects of PI 3-kinase are not mediated through Bad phosphorylation in cardiac muscle cells. To determine whether activation of caspase 3 is sufficient to induce apoptosis in cardiomyocytes, an engineered TAT-caspase 3 protein was introduced to cardiomyocytes. Significant reduction of cell viability occurred in the cardiomyocytes transduced with active caspase 3, indicating that activation of caspase 3 is sufficient to cause cardiomyocyte death. These findings indicate the existence of an IGF-I receptor-PI 3-kinase-caspase 3 pathway in cardiomyocytes that plays an important role in the anti-apoptotic actions of IGF-I in heart. Moreover, these data suggest that modulation of PI 3-kinase activities may represent a potential therapeutic strategy to counteract the occurrence of apoptosis in cardiomyopathy.

Animals↗

PubMed2000

High-resolution inkjet printing of all-polymer transistor circuits.

Direct printing of functional electronic materials may provide a new route to low-cost fabrication of integrated circuits. However, to be useful it must allow continuous manufacturing of all circuit components by successive solution deposition and printing steps in the same environment. We demonstrate direct inkjet printing of complete transistor circuits, including via-hole interconnections based on solution-processed polymer conductors, insulators, and self-organizing semiconductors. We show that the use of substrate surface energy patterning to direct the flow of water-based conducting polymer inkjet droplets enables high-resolution definition of practical channel lengths of 5 micrometers. High mobilities of 0.02 square centimeters per volt second and on-off current switching ratios of 10(5) were achieved.

Journal Article↗

PubMed2000

Regulation of somatic growth by the p160 coactivator p/CIP.

A family of p160 coactivators was initially identified based on ligand-dependent interactions with nuclear receptors and thought to function, in part, by recruiting CREB-binding protein/p300 to several classes of transcription factors. One of the p160 factors, p/CIP/AIB1, often amplified and overexpressed in breast cancer, also exhibits particularly strong interaction with CREB-binding protein/p300. In this manuscript, we report that p/CIP, which exhibits regulated transfer from cytoplasm to nucleus, is required for normal somatic growth from embryonic day 13.5 through maturity. Our data suggest that a short stature phenotype of p/CIP gene-deleted mice reflect both altered regulation of insulin-like growth factor-1 (IGF-1) gene expression in specific tissues and a cell-autonomous defect of response to IGF-1, including ineffective transcriptional activities by several classes of regulated transcription factors under specific conditions. The actions of p/CIP are therefore required for full expression of a subset of genes critical for regulating physiological patterns of somatic growth in mammals.

Animals↗

PubMed2000

Gene expression monitoring for gene discovery in models of peripheral and central nervous system differentiation, regeneration, and trauma.

Gene expression monitoring using gene expression microarrays represents an extremely powerful technology for gene discovery in a variety of systems. We describe the results of seven experiments using Incyte GEM technology to compile a proprietary portfolio of data concerning differential gene expression in six different models of neuronal differentiation and regeneration, and recovery from injury or disease. Our first two experiments cataloged genes significantly up- or down-regulated during two phases of the retinoic acid-induced differentiation of the embryonal carcinoma line Ntera-2. To identify genes involved in neuronal regeneration we performed three GEM experiments, which included changes in gene expression in rat dorsal root ganglia during the healing of experimentally injured sciatic nerve, in regenerating neonatal opossum spinal cord, and during lipopolysaccharide stimulation of primary cultures of rat Schwann cells. Finally we have monitored genes involved in the recovery phase of the inflammatory disease of the rat spinal cord, experimental allergic encephalomyelitis, as well as those responsible for protection from oxidative stress in a glutamate-resistant rat hippocampal cell line. Analysis of the results of the approximately 70,000 data points collected is presented.

Animals↗

PubMed2000

Lysine 2,3-aminomutase and trans-4,5-dehydrolysine: characterization of an allylic analogue of a substrate-based radical in the catalytic mechanism.

An analogue of lysine, trans-4,5-dehydro-L-lysine (trans-4, 5-dehydrolysine), is a potent inhibitor of lysine 2,3-aminomutase from Clostridium subterminale SB4 that competes with L-lysine for binding to the active site. Inclusion of trans-4,5-dehydrolysine with activated enzyme and the coenzymes pyridoxal-5'-phosphate and S-adenosylmethionine, followed by freezing at 77 K, produces an intense signal in the electron paramagnetic resonance (EPR) spectrum at g 2.0, which is characteristic of an organic radical. A series of deuterated and (15)N-labeled samples of trans-4,5-dehydrolysine were synthesized and used to generate the EPR signal. Substitution of deuterium for hydrogen at C2, C3, C4, C5, and C6 of trans-4, 5-dehydrolysine led to significant simplifications and narrowing of the EPR signal, showing that the unpaired electron was located on the carbon skeleton of 4,5-trans-4,5-dehydrolysine. The hyperfine splitting pattern is simplified by use of 4,5-dehydro[3, 3-(2)H(2)]lysine or 4,5-dehydro[4,5-(2)H(2)]lysine, and it is dramatically simplified with 4,5-dehydro-[3,3,4,5,6,6-(2)H(6)]lysine. Spectral simulations show that the EPR signal arises from the allylic radical resulting from the abstraction of a hydrogen atom from C3 of trans-4,5-dehydrolysine. This radical is an allylic analogue of the substrate-related radical in the rearrangement mechanism postulated for this enzyme. The rate constant for formation of the 4,5-dehydrolysyl radical (2 min(-)(1)) matches that for the decrease in the concentration of [4Fe-4S](+), showing that the two processes are coupled. The cleavage of S-adenosylmethionine to 5'-deoxyadenosine and methionine takes place with a rate constant of approximately 5 min(-)(1). These kinetic correlations support the hypothesis that radical formation results from a reversible reaction between [4Fe-4S](+) and S-adenosylmethionine at the active site to form [4Fe-4S](2+), the 5'-deoxyadenosyl radical, and methionine as intermediates.

Binding Sites↗

PubMed2000

Effects of neurotrophic factors on motoneuron survival following axonal injury in newborn rats.

Using two different lesion models, the spinal root avulsion and the distal nerve axotomy, the present study investigated effects of known neurotrophic factors on motoneuron survival in newborn rats. Results of the present study show that 100% of motoneurons in the lesioned spinal segment die at 1 week following root avulsion, and more than 80% of them die at 2 weeks following distal nerve axotomy. Local application of GDNF can rescue 92% of motoneurons up to 1 week from degeneration due to root avulsion and almost 100% of them up to 2 weeks from degeneration due to distal nerve axotomy. Local application of BDNF fails to prevent any motoneuron death in newborn rats following root avulsion, but it can rescue about 50% of motoneurons up to 2 weeks from degeneration due to distal nerve axotomy. CNTF and IGF-1 fail to prevent any motoneuron death following either distal nerve axotomy or root avulsion. Thus, comparing all the neurotrophic factors tested in this study, GDNF is most effective in preventing death of motoneurons following axonal injury in newborn rats.

Animals↗

PubMed2000

Construction and characterization of a heterodimeric iron protein: defining roles for adenosine triphosphate in nitrogenase catalysis.

One molecule of MgATP binds to each subunit of the homodimeric Fe protein component of nitrogenase. Both MgATP molecules are hydrolyzed to MgADP and P(i) in reactions coupled to the transfer of one electron into the MoFe protein component. As an approach to assess the contributions of individual ATP binding sites, a heterodimeric Fe protein was produced that has an Asn substituted for residue 39 in the ATP binding domain in one subunit, while the normal Asp(39) residue within the other subunit remains unchanged. Separation of the heterodimeric Fe protein from a mixed population with homodimeric Fe proteins contained in crude extracts was accomplished by construction of a seven His tag on one subunit and a differential immobilized-metal-affinity chromatography technique. Three forms of the Fe protein (wild-type homodimeric Fe protein [Asp(39)/Asp(39)], altered homodimeric Fe protein [Asn(39)/Asn(39)], and heterodimeric Fe protein [Asp(39)/Asn(39)]) were compared on the basis of the biochemical and biophysical changes elicited by nucleotide binding. Among those features examined were the MgATP- and MgADP-induced protein conformational changes that are manifested by the susceptibility of the [4Fe-4S] cluster to chelation and by alterations in the electron paramagnetic resonance, circular dichroism, and midpoint potential of the [4Fe-4S] cluster. The results indicate that changes in the [4Fe-4S] cluster caused by nucleotide binding are the result of additive conformational changes contributed by the individual subunits. The [Asp(39)/Asn(39)] Fe protein did not support substrate reduction activity but did hydrolyze MgATP and showed MgATP-dependent primary electron transfer to the MoFe protein. These results support a model where each MgATP site contributes to the rate acceleration of primary electron transfer, but both MgATP sites must be functioning properly for substrate reduction. Like the altered homodimeric [Asn(39)/Asn(39)] Fe protein, the heterodimeric [Asp(39)/Asn(39)] Fe protein was found to form a high affinity complex with the MoFe protein, revealing that alteration on one subunit is sufficient to create a tight complex.

Adenosine Triphosphate↗

PubMed2000

Activated leukocytes oxidatively damage DNA, RNA, and the nucleotide pool through halide-dependent formation of hydroxyl radical.

A variety of chronic inflammatory conditions are associated with an increased risk for the development of cancer. Because of the numerous links between DNA oxidative damage and carcinogenesis, a potential role for leukocyte-generated oxidants in these processes has been suggested. In the present study, we demonstrate a novel free transition metal ion-independent mechanism for hydroxyl radical ((*)OH)-mediated damage of cellular DNA, RNA, and cytosolic nucleotides by activated neutrophils and eosinophils. The mechanism involves reaction of peroxidase-generated hypohalous acid (HOCl or HOBr) with intracellular superoxide (O(2)(*)(-)) forming (*)OH, a reactive oxidant species implicated in carcinogenesis. Incubation of DNA with either isolated myeloperoxidase (MPO) or eosinophil peroxidase (EPO), plasma levels of halides (Cl(-) and Br(-)), and a cell-free O(2)(*)(-) -generating system resulted in DNA oxidative damage. Formation of 8-hydroxyguanine (8-OHG), a mutagenic base which is a marker for (*)OH-mediated DNA damage, required peroxidase and halides and occurred in the presence of transition metal chelators (DTPA +/- desferrioxamine), and was inhibited by catalase, superoxide dismutase (SOD), and scavengers of hypohalous acids. Similarly, exposure of DNA to either neutrophils or eosinophils activated in media containing metal ion chelators resulted in 8-OHG formation through a pathway that was blocked by peroxidase inhibitors, hypohalous acid scavengers, and catalytically active (but not heat-inactivated) catalase and SOD. Formation of 8-OHG in target cells (HA1 fibroblasts) occurred in all guanyl nucleotide-containing pools examined following exposure to both a low continuous flux of HOCl (at sublethal doses, as assessed by [(14)C]adenine release and clonogenic survival), and hyperoxia (to enhance intracellular O(2)(*)(-) levels). Mitochondrial DNA, poly A RNA, and the cytosolic nucleotide pool were the primary targets for oxidation. Moreover, modest but statistically significant increases in the 8-OHG content of nuclear DNA were also noted. These results suggest that the peroxidase-H(2)O(2)-halide system of leukocytes is a potential mechanism contributing to the well-established link between chronic inflammation, DNA damage, and cancer development.

Animals↗

PubMed2000

Survival and regeneration of motoneurons in adult rats by reimplantation of ventral root following spinal root avulsion.

The present study examines whether reimplantation of the ventral root could prevent motoneuron death after root avulsion. In the control animals about 65% or 39% of motoneurons survived at 3 or 6 weeks post-injury respectively. More than 60% of them expressed nitric oxide synthase (NOS). In contrast, in animals with ventral root reimplantation, nearly 90% or 80% of motoneurons survived at 3 or 6 weeks post-injury respectively. Expression of NOS due to root avulsion was significantly inhibited in these experimental animals. More interestingly, about 80% of the surviving motoneurons were found to regenerate their axons into the reimplanted ventral root, and all of these regenerating motoneurons were NOS negative. Results of the present study show that reimplantation of avulsed ventral root can greatly enhance motoneuron survival and the surviving motoneurons can regrow their axons into the original ventral root.

Animals↗

PubMed2000

Construction and characterization of a Schistosoma mansoni bacterial artificial chromosome library.

A bacterial artificial chromosome (BAC) library has been established from genomic DNA isolated from the trematode parasite of human, Schistosoma mansoni. This library consists of more than 21,000 recombinant clones carrying inserts in the pBeloBAC11 vector. The mean insert size was 100 kb, representing an approximate 7.95-fold genome coverage. Library screening with eight chromosome-specific or single-copy gene probes yielded between 1 and 9 positive clones, and none of those tested was absent from the library. End sequences were obtained for 93 randomly selected clones, and 37 showed sequence identity to S. mansoni sequences (ESTs, genes, or repetitive sequences). A preliminary analysis by fluorescence in situ hybridization localized 8 clones on schistosome chromosomes 1 (2 clones), 2, 3, 5, Z, and W (3 clones). This library provides a new resource for the physical mapping and sequencing of the genome of this important human pathogen.

Animals↗

PubMed2000

Chondroitinase ABC promotes axonal regeneration of Clarke's neurons after spinal cord injury.

We examined whether enzymatic digestion of chondroitin sulfate (CS) promoted the axonal regeneration of neurons in Clarke's nucleus (CN) into a peripheral nerve (PN) graft following injury of the spinal cord. After hemisection at T11, a segment of PN graft was implanted at the lesion site. Either vehicle, brain-derived neurotrophic factor (BDNF) or chondroitinase ABC was applied at the implantation site. The postoperative survival period was 4 weeks. Treatment with vehicle or BDNF did not promote the axonal regeneration of CN neurons into the PN graft. Application of 2.5 unit/ml chondroitinase ABC resulted in a significant increase (12.8%) in the number of regenerated CN neurons. Double labeling with Fluoro-Gold and NADPH-diaphorase histochemistry showed that the regenerated CN neurons did not express nitric oxide synthase (NOS). Our results suggest that CS is inhibitory to the regeneration of CN neurons following injury of the spinal cord.

Animals↗

PubMed2000

A low-voltage droplet charging circuit with simulative cell-sorting function for flow cytometer-cell sorter.

BACKGROUND: Flow cytometer cell sorters have become important tools in many biological laboratories. Commercial electrically-deflected cell sorters that deflect wanted cells in electrically charged droplets need high-voltage amplifiers which are expensive and difficult to obtain. Effort was made to build an alternative droplet charging circuit with low-voltage amplifiers that are much easier to get and have more reasonable price. METHODS: A low-voltage charging circuit was designed. Every time a cell was to be separated, a pair of complementary charging pulses were produced: one was positive and the other was negative with equal amplitude. These were enlarged by two low-voltage charging amplifiers to drive two charging electrodes respectively. RESULTS: Due to the effect of addition, the voltage between the two electrodes was double as high as the output of either amplifier. The result of test experiment proved that the cell sorter with low-voltage amplifiers, which was cheaper and easier to obtain, could separate cells as efficiently as the instrument with high-voltage ones that were more expensive and more difficult to make. In addition, a simulative cell-sorting function was provided. CONCLUSIONS: This low-voltage, easily-built and low-price charging circuit for flow cytometer cell sorter is a good alternative to the commonly used high-voltage one, especially to researcher who hopes to build his own personal instrument.

Animals↗

PubMed2000

Social isolation stress enhanced liver metastasis of murine colon 26-L5 carcinoma cells by suppressing immune responses in mice.

We investigated the effect of social isolation stress on the formation of experimental liver metastasis resulted from intraportal vein (i.p.v.) injection of colon 26-L5 carcinoma cells in male Balb/c mice, and elucidated some of the underlying mechanism involving the effects of this stress on cellular immunity. Increases in the colony number and tumor burden were observed in the mice socially isolated before and/or after tumor cell challenge, as compared with the group-housed mice. In addition, exposure of mice to 2 weeks of preisolation resulted in decreases in the thymus weight and number of thymocytes by 35.8% and 40.2%, respectively, in comparison with the controls. Reduced proliferative response of splenocytes to various stimuli and suppressed splenic NK activity, as well as decreased macrophage-mediated cytotoxicity, were also found in the mice exposed to social isolation. Thus, these results suggest that social isolation stress enhances tumor metastasis in part via its suppressive effect on the immune system of the host.

Animals↗