Biomedical subjects

J Wu

Publications and source records attributed to J Wu.

At least 415 records · Page 23Linked to original sources

PubMed2000

Functional analysis of eight open reading frames on chromosomes XII and XIV of Saccharomyces cerevisiae.

Deletion, together with basic functional and bioinformatic analyses has been carried out on eight novel ORFs discovered during the sequencing of the Saccharomyces cerevisiae genome. Six ORFs (YLL049w, YLL051c, YLL052c, YLL053c, YLL054c and YLL055w) located on the left arm, and one (YLR130c) on the right arm, of chromosome XII, and an eighth ORF (YNL331c) on the left arm of the chromosome XIV, have been investigated. ORFs were deleted by the SFH-PCR gene-replacement strategy. Basic functional analysis revealed no obvious phenotype for any of the eight ORFs. Bioinformatic analysis, however, revealed possible functions for seven of the ORFs on the basis of the amino acid sequence similarity of their predicted protein products to those of proteins with known functions. ORF YLL051c (FRE6) shows similarity to iron transport proteins, such as ferric reductase. YLL052c and YLL053c appear to be aquaporins. The product of YLL054c (Yll054p) is highly similar to the oleate-specific transcriptional activator protein (Pip2p), which is involved in the peroxisomal induction pathway (pip). ORF YLL055w is similar to Dal5p, allantoate permease, and may play role in allantoin transport. YLR130c (ZRT2) is a low-affinity zinc transporter protein. YNL331c is also named AAD14, which is induced by chemicals that induce oxidative stress by depleting the cell of glutathione.

Chromosomes, Fungal↗

PubMed2000

Evidence of nucleophilic addition to chemiluminescent N-sulfonylacridinium-9-carboxamides from electrospray ionization mass spectrometry.

Addition of nucleophiles to the chemiluminescent acridinium-9-carboxamide 1 resulted in the formation of the acridan adduct 7. The relative ratio of 1/7 present in solution could be determined by electrospray ionization mass spectrometry (ESI-MS) for a number of nucleophiles that are commonly employed during the use of 1 as a label in medical diagnostic assays.

Acridines↗

PubMed2000

Water maze and radial maze learning and the density of binding sites of glutamate, GABA, and serotonin receptors in the hippocampus of inbred mouse strains.

Correlations between the densities of ionotropic glutamate, GABA(A), and serotonin binding sites in the hippocampus of seven inbred mouse strains and strain-specific learning capacities in two types of maze were studied. Binding site densities were measured with quantitative receptor autoradiography. Learning capacities were determined in a water maze task as well as in spatial and nonspatial versions of an eight-arm radial maze. The densities of most binding sites differed significantly between the strains in the subfields of Ammon's horn (CA1 and CA3) and the dentate gyrus, except for serotonin binding sites in CA1. By comparing the different strains, significant receptor-behavioral correlations between the densities of the GABA(A) receptors and the activity-dependent behavior in the water maze as well as the spatial learning in the radial maze were found. The densities of D,L-alpha-amino-3-hydroxy-5-methyl-4-isoxalone propionate (AMPA) and kainate receptors correlated positively with learning capacity in the spatial eight-arm radial maze. We conclude that hereditary variations mainly in AMPA, kainate, and GABA(A) receptor densities are involved in behavioral variations in spatial and nonspatial learning tasks.

Analysis of Variance↗

PubMed2000

Multiple channel phased arrays for echo planar imaging.

A new interface combining phased arrays and echo-planar imaging (EPI) technologies was developed for two channel breast MR EPI applications. A detailed design for a dual-channel, EPI-compatible, phased array breast coil is described. EPI digital data multiplexing, signal controlling and sampling schemes are also presented. Results from breast phantoms and patients demonstrate a 55% improvement in signal-to-noise ratio when compared to a conventional two-loop, single channel coil configuration. This method can be easily expanded to a four or more channel, EPI-compatible, phased array system to improve field-of-view coverage and signal-to-noise ratio.

Biomedical Engineering↗

PubMed2000

Diffuse and marked breast uptake of both 123I-BMIPP and 99mTc-TF by myocardial scintigraphy.

Unexpected breast uptake was observed in a 32-year-old woman referred for evaluation of hypertrophic cardiomyopathy. Diffuse and marked bilateral breast uptake of 123I-BMIPP and 99mTc-TF was shown by both planar and SPECT imaging during the first study, and the uptake of both radionuclides had decreased significantly eleven months later. At the time of the first radionuclide examination, she was occasionally breast feeding her 2-year-old child and had small amounts of milk production. At the follow up examination, the frequency of breast feeding was significantly reduced and she produced only small amounts of milk. Therefore, the uptake of 123I-BMIPP and 99mTc-TF may have been caused by lactation.

Adult↗

PubMed2000

Evolution of cis-acting elements in 5' flanking regions of vertebrate actin genes.

Regulation of the vertebrate actin multigene family involves the recognition of various regulatory sequences (cis-acting elements) that specify the distinct tissue type and developmental program of expression for each actin paralogue, which implies that the distribution of cis-acting elements may be unique for each paralogue gene. To elucidate the evolution of these unique distribution patterns, we improved a method to scan for cis-acting elements in the 5' flanking regulatory region of genes and used it to analyze five cis-acting elements (SRE, MyoD binding site, Elk-1 binding site, positive and negative YY1 binding sites) of six actin paralogue genes (beta and gamma cytoplasmic actins, alpha and gamma smooth muscle actins, and alpha skeletal and alpha cardiac actins) among various vertebrates. It was shown that although an element(s) may exist in all paralogue genes of the same species, its numbers, compositions, and distribution patterns or even sequences vary remarkably among paralogues, which contributes to their different tissue- and developmental-specific expression. However, each pair of coexpressed paralogues has some certain similarity in distribution patterns. Furthermore, among various orthologues of actin genes derived from diverse vertebrates, the sequences, numbers, and distribution patterns of these cis-acting elements are highly conserved or even identical in the long run of phylogeny of vertebrates. Taken together, the results described above strongly indicate that not only the structures of actins but also their expression patterns are essential in both the phylogeny and the physiology of vertebrates. The distribution patterns of cis-acting elements of various actin genes can be regarded as indicators of both horizontal (paralogues) and vertical (orthologous) evolution of actins.

Actins↗

PubMed2000

Hepatic stellate cells: a target for the treatment of liver fibrosis.

Hepatic fibrosis is a wound-healing process that occurs when the liver is injured chronically. Hepatic stellate cells (HSC) are responsible for the excess production of extracellular matrix (ECM) components. The activation of HSC, a key issue in the pathogenesis of hepatic fibrosis, is mediated by various cytokines and reactive oxygen species released from the damaged hepatocytes and activated Kupffer cells. Therefore, inhibition of HSC activation and its related subsequent events, such as increased production of ECM components and enhanced proliferation, are crucial goals for intervention in the hepatic fibrogenesis cascade. This is especially true when the etiology is unknown or there is no established therapy for the cause of the chronic injury. This review explores the rationale for choosing HSC as a target for the pharmacological, molecular, and other novel therapeutics for hepatic fibrosis. One focus of this review is the inhibition of two cytokines, transforming growth factor-beta and platelet-derived growth factor, which are important in hepatic fibrogenesis. A number of new agents, such as Chinese herbal recipes and herbal extracts, silymarin, S-adenosyl-L-methionine, polyenylphosphatidylcholine, and pentoxifylline are also discussed.

Antioxidants↗

PubMed2000

Successful sealing of fetoscopic access sites with collagen plugs in the rabbit model.

OBJECTIVE: The aim of this study was to evaluate the efficacies of various plugging techniques in sealing the membrane defect created by fetoscopy in the rabbit at midgestation. STUDY DESIGN: Fetoscopy was performed in pregnant rabbits at 23 days' gestation (term, 32 days' gestation). In group 1 fetal sacs were left unclosed (positive control group, n = 24). In group 2 injection with commercially available extracellular matrix (Matrigel; BD Labware, Bedford, Mass) was performed and a myometrial suture was inserted (n = 23). In group 3 the entry site was plugged with collagen (Colgen; Inter-Phar, Paris, France) combined with a myometrial suture (n = 22). At 30 days' gestation the membrane integrity, amniotic fluid presence, and fetal lung/body weight ratios were assessed. The plugging site was examined histologically. RESULTS: The use of suture and collagen plugs (group 3) resulted in functional restoration of membrane integrity with preservation of amniotic fluid and normal fetal lung/body weight ratio at term in 82% of cases, compared with 42% in the positive control group (group 1; P <.05). Histologic examination revealed entrapment of membranes between the plug and the myometrium but no anatomic repair of the membranes. The use of suture and extracellular matrix (group 2) did not achieve better results than those seen in group 1 (positive control group). CONCLUSION: Collagen plugs achieved functional sealing of fetoscopic access sites in a rabbit model and prevented oligohydramnios and pulmonary hypoplasia.

Amnion↗

PubMed2000

Maturation and apoptosis of human oocytes in vitro are age-related.

OBJECTIVE: To study the morphological changes of apoptotic oocytes, and rates of in vitro maturation and apoptosis of human oocytes in relation to age. DESIGN: Prospective comparative study. SETTING: Reproductive medicine center. PATIENT(S): Women undergoing surgery for ovarian cysts. INTERVENTION(S): Oocytes were incubated in Ham's F-10 medium with 15% fetal cord serum (FCS) for 32 to 120 hours and were examined under inverted microscope every 6 to 8 hours. MAIN OUTCOME MEASURE(S): Oocyte maturation and apoptosis, Fas antigen. RESULT(S): The morphologic changes characteristic of apoptosis oocytes were shrinkage, or the occurrence of cytoplasmic condensation, membrane blebbing, fragmentation of the oocyte into "apoptotic" bodies of unequal size, or internucleosomal DNA cleavage as shown by TUNEL. The maturation rates of oocytes were highest in those from women aged 21 to 30 years, and lowest in those aged 41 to 50 years. Apoptosis occurred in 17.1% (age group 21 to 30 years), 37. 7% (31 to 40 years), and 52.3% (41 to 50 years). The rate of apoptosis of human immature oocytes cultured in vitro was significantly higher in those from older women who were 41 to 50 years old than in those women 21 to 40 years old. Fas antigen was found to be present on apoptotic oocyte membranes. CONCLUSION(S): The developmental potential of oocytes from older women decreased in vitro in a manner similar to that seen in vivo. DNA fragmentation in oocytes associated with apoptotic death might be one of the reasons for poor oocyte quality and lower fertility in older women. Fas antigen in the oocyte presumably mediates apoptosis.

Adult↗

PubMed2000

Evaluation of chemiluminescent estradiol conjugates by using a surface plasmon resonance detector.

A series of chemiluminescent 17beta-estradiol probes were synthesized. Relative equilibrium dissociation constants (K(D)) for the interaction of an anti-E(2) Fab fragment for the probes in solution were evaluated using a single E(2)-analog biosensor surface on a BIAcore surface plasmon resonance instrument. The results show the antibody fragment binds all chemiluminescent conjugates tested with high affinity showing only minor preferences for site of substitution (C6 versus C7), stereochemistry (alpha versus beta), or linker moiety.

Antibodies, Monoclonal↗

PubMed2000

Reflectometry using longitudinal, shear and Rayleigh waves.

A new technique of reflectometry using longitudinal, shear and Rayleigh waves is presented. Reflection coefficient as a function of angle incidence of an ultrasound beam with a finite beamwidth was measured for water-aluminum, water-brass, and water-glass interfaces. The measured values have matched very favorably with the results of numerical calculations based on the angular spectrum of waves method. It has been shown that the speeds of longitudinal, shear and Rayleigh waves of a solid can be determined very accurately by measuring a spectacularly reflected signal versus angle of incidence.

Alloys↗

PubMed2000

NK cell activation: distinct stimulatory pathways counterbalancing inhibitory signals.

A delicate balance between positive and negative signals regulates NK cell effector function. Activation of NK cells may be initiated by the triggering of multiple adhesion or costimulatory molecules, and can be counterbalanced by inhibitory signals induced by receptors for MHC class I. A common pathway of inhibitory signaling is provided by immunoreceptor tyrosine-based inhibitory motifs (ITIMs) in the cytoplasmic domains of these receptors which mediate the recruitment of SH2 domain-bearing tyrosine phosphate-1 (SHP-1). In contrast to the extensive progress that has been made regarding the negative regulation of NK cell function, our knowledge of the signals that activate NK cells is still poor. Recent studies of the activating receptor complexes have shed new light on the induction of NK cell effector function. Several NK receptors using novel adaptors with immunoreceptor tyrosine-based activation motifs (ITAMs) and with PI 3-kinase recruiting motifs have been implicated in NK cell stimulation.

Adaptor Proteins, Signal Transducing↗

PubMed2000

An organ-culture for in vitro evaluation of fetal membrane healing capacity.

OBJECTIVES: We aimed to set up an organ culture of human amniochorion to evaluate fetal membrane repair capacity following surgical trauma. METHODS: Fetal membranes were collected from four patients, during elective caesarean section at term. Explants were traumatised at the centre and cultured on collagen support material for a total of 12 days. Viability was assessed by light microscopy and proliferation by detection of 5-Bromo-2' deoxy-Uridine (BrdU) incorporation and immunohistochemistry. Wound healing capacity was assessed trough photographic documentation every 2 days. RESULTS: Cultures showed good survival for 12 days. Increased cellularity, survival and proliferations were observed at the borders of the cultures in contrast to the central trauma site. During the 12 days observation period, no significant closure of the membrane defect could be demonstrated. CONCLUSION: This organ culture system represents a new model for the study of human fetal membrane repair. Despite good survival and localised proliferation, no obvious closure of a surgically created defect was observed in the described culture conditions.

Extraembryonic Membranes↗

PubMed2000

Ultrasound shear wave imaging for bone.

Recently, a computer-controlled scanning ultrasound (US) imaging system was developed in our laboratory. It includes a pair of broadband 48-MHz focusing copolymer transducers. The apertures of the transducers and their f-numbers were identically equal to 2 mm and 2.25, respectively. A specimen can be moved in a 10-microm increment in its plane and its normal direction can be rotated along the US propagation direction. It can be used to produce transmission-mode images of shear waves, as well as longitudinal waves for solid specimens. Shear waves in solids were generated by mode conversion. The results of the longitudinal and shear-wave US images for a piece of compact bovine bone obtained using this system are presented. Shear-wave images combined with longitudinal images can provide a more complete mechanical characterization of bone.

Animals↗

PubMed2000

Experimental study of the effects of Optison concentration on sonoporation in vitro.

Lethal sonoporation and reparable sonoporation were observed in Jurkat lymphocytes in suspension with the addition of varying amounts of Optison, a commercially available bubble-based contrast agent. For given ultrasound (US) exposure conditions (spatial peak-pressure amplitude of 0.2 MPa, duty cycle 10% and 2-MHz frequency), sonoporation was directly related to the bubble-to-cell ratio (in a range from 0 to 230). It was found that the nearest bubble-cell spacing was also related to the occurrence frequency of bioeffects. A constant bubble-to-cell ratio often provided very different results for two different initial cell concentrations (200,000 cells/mL and 600,000 cells/mL), with the higher cell concentration generally exhibiting higher levels of sonoporation. In contrast, a constant bubble-to-cell spacing provided similar results between the two initial cell concentrations. The frequency of reparable and lethal sonoporation was seen to decay as the inverse-cube power of the nearest bubble-cell spacing. Significant reparable sonoporation was observed at a bubble-cell spacing that was 10 microm larger than the minimum spacing at which significant lethal sonoporation was observed. Preliminary analysis also suggests the possibility of a step-wise increase in lethal sonoporation as spacing decreases; further experiment is needed.

Albumins↗

PubMed2000

Fos expression is induced by increased nitric oxide release in rat spinal cord dorsal horn.

The relationship between exogenous or endogenous nitric oxide and c-fos, an immediate-early gene which can further activate the production of other substances in the central nervous system, was investigated in this study. We found that Fos expression is increased after intradermal capsaicin injection, which also leads to endogenous nitric oxide release in the spinal cord. The increased Fos expression is distributed in neurons of the superficial layers and lamina V of the dorsal horn on the side ipsilateral to the injection. The increased Fos expression is blocked by N(G)-nitro-L-arginine methyl ester, a nitric oxide synthase inhibitor, but not by its inactive isomer N(G)-nitro-D-arginine methyl ester. Fos expression was also increased following the perfusion of 3-morpholino-sydnonimine, a nitric oxide donor, into the dorsal horn through a microdialysis fiber. The increased Fos was distributed within 400 microm from the edge of the microdialysis fiber. Although Fos expression was increased with 3-morpholino-sydnonimine perfusion compared to that seen with artificial cerebrospinal fluid perfusion, there was still some Fos immunostaining in the control sections. Following perfusion of artificial cerebrospinal fluid in the spinal cord of rats pretreated with N(G)-nitro-L-arginine methyl ester, it was found that Fos staining was reduced significantly compared to the control sections from animals without N(G)-nitro-L-arginine methyl ester pretreatment. These results suggest that nitric oxide helps mediate Fos expression induced by an intradermal capsaicin injection. We conclude that both endogenous and exogenous nitric oxide induce Fos expression. Involvement of nitric oxide in the development of central sensitization may affect nociceptive processing by increasing Fos expression. Since many other substances which are related to pain mechanisms can be induced by Fos, it is suggested that nitric oxide may regulate production of these substances through activation of Fos. Nitric oxide is not only involved in the development of central sensitization, but is also involved in the activation of control mechanisms affecting nociception.

Animals↗

PubMed2000

A multi-element ICP-MS survey method as an alternative to the heavy metals limit test for pharmaceutical materials.

A multi-element inductively coupled plasma-mass spectrometry (ICP-MS) survey method has been demonstrated as an alternative to the antiquated 'heavy metals limit test' prescribed by United States Pharmacopoeia (USP), European Pharmacopoeia (EP), and British Pharmacopoeia (BP), for drug substances, intermediates, and raw materials. The survey method is simple, fast, sensitive, semi-quantitative to quantitative, and includes all the elements which can be analyzed by atomic spectroscopy.

Calibration↗

PubMed2000

Purification and characterization of a cystatin from the leaves of methyl jasmonate treated tomato plants.

A multidomain cystatin was purified from the leaves of mature and seedling tomato plants (Lycopersicon esculentum, cv Bonnie Best) that had been sprayed with methyl jasmonate. For seedlings, cystatin purification was accomplished using EDTA washing, KCI extraction, 70 degrees C heat treatment, ammonium sulfate fractionation and gel filtration chromatography. For mature plants, DEAE chromatography was also needed to separate a protease, hydrolysis products of cystatin and serine proteinase inhibitors from the intact cystatin. Purified tomato cystatin has a molecular weight (Mr) of 88 kDa, eight papain binding domains, is a non-competitive inhibitor of papain with K1 of 1.4 nM and is not a glycoprotein. Tryptic peptides (Mr 26, 13 kDa) and most chymotryptic peptides (Mr 33, 13 kDa) of tomato cystatin retain inhibitor activity. Amino acid analysis revealed no Cys; Asx, Glx, Gly, Ser accounted for almost half the residues and there was some homology with potato multicystatin. Activity is stable at pH 4-11 at 4 degrees C, but unstable at neutral pH at > 60 degrees C (Ea = 92.5 kJ/mole). Extracts of mature plants treated with methyl jasmonate contain lower Mr cystatins that appear to result from the action of an endogenous 26 kDa protease on the 88 kDa inhibitor.

Acetates↗