Biomedical subjects

M Lu

Publications and source records attributed to M Lu.

At least 19 recordsLinked to original sources

PubMed2005

MRI-guided, open trial of abciximab for ischemic stroke within a 3- to 24-hour window.

The authors assessed the effect of IV abciximab on early neurologic improvement and ischemic lesion growth in 29 patients with supratentorial stroke and NIH stroke scale score (NIHSSS) > or = 4 (11.1 +/- 5.9), treated within 3 to 24 (13.6 +/- 5.5) hours of onset. The 48 to 72-hour NIHSSS improvement was 4.4 +/- 3.2 and the 24-hour lesion growth on DWI was +23% (-50%, +103%); 7/26 (27%) patients experienced lesion size decrease. Treatment of sub-24-hour stroke with abciximab improves early post-treatment neurologic status and often attenuates ischemic lesion growth.

Abciximab↗

PubMed2005

Identification of the pathological prion protein allotypes in scrapie-infected heterozygous bank voles (Clethrionomys glareolus) by high-performance liquid chromatography-mass spectrometry.

Cerebral formation of the pathological isoform of the prion protein (PrP) is a crucial molecular event in prion diseases. The bank vole (Clethrionomys glareolus) is a rodent species highly susceptible to natural scrapie. The PrP gene of bank vole is polymorphic (Met/Ile) at codon 109. Here we show that homozygous 109Met/Met voles have incubation times shorter than heterozygous 109Met/Ile voles after experimental challenge with three different scrapie isolates. An HPLC-MS/MS method was optimized and applied to investigate whether in heterozygous animals both PrP allotypes are able to undergo pathological conversion. The results demonstrate that both allotypes of the prion protein participate to pathological deposition.

Amino Acid Sequence↗

PubMed2005

Fluctuation of the cytokine expression in the liver during the chronic woodchuck hepatitis virus (WHV) infection is not related to viral load.

The woodchuck together with the woodchuck hepatitis virus (WHV) is an excellent model to study the pathogenesis of hepadnaviral infections. Chronic WHV infection causes severe liver disease and hepatocellular carcinoma in woodchucks. The mechanism of viral clearance is not fully understood, interferons seem to play a major role in down-regulating viral replication prior to elimination of infected hepatocytes. We investigated on the pattern of cytokine and T-cell-marker expression in livers of woodchucks chronically infected with WHV. RNase-protection-assay (RPA) was used to determine mRNA of woodchuck specific genes (TNF-alpha, IFN-gamma, IL-15, CD3, CD4, CD8). Serial liver biopsies were performed daily or weekly in eight chronic WHV-carrier woodchucks. Cytokine/T-cell-marker expression differed significantly between the time points up to +/-50% within each woodchuck. The different expression patterns of cytokines or T-cell-markers did not correlate to the (weak) fluctuations in the viremia but may explain the observed fluctuations in the WHV/HBV-load in chronically infected individuals. Furthermore, we observed associations between cytokine and T-cell-marker expression. The marginal fluctuations in viremia during the chronic infection may indicate, that, once the chronic hepadnaviral infection is established, cytokines/interferons expressed endogenously (i.e. not vector-borne or injected) play only a minor role.

Animals↗

PubMed2005

The genome of the social amoeba Dictyostelium discoideum.

The social amoebae are exceptional in their ability to alternate between unicellular and multicellular forms. Here we describe the genome of the best-studied member of this group, Dictyostelium discoideum. The gene-dense chromosomes of this organism encode approximately 12,500 predicted proteins, a high proportion of which have long, repetitive amino acid tracts. There are many genes for polyketide synthases and ABC transporters, suggesting an extensive secondary metabolism for producing and exporting small molecules. The genome is rich in complex repeats, one class of which is clustered and may serve as centromeres. Partial copies of the extrachromosomal ribosomal DNA (rDNA) element are found at the ends of each chromosome, suggesting a novel telomere structure and the use of a common mechanism to maintain both the rDNA and chromosomal termini. A proteome-based phylogeny shows that the amoebozoa diverged from the animal-fungal lineage after the plant-animal split, but Dictyostelium seems to have retained more of the diversity of the ancestral genome than have plants, animals or fungi.

ATP-Binding Cassette Transporters↗

PubMed2005

Exotic meson decay to omegapi0pi-.

A partial-wave analysis of the mesons from the reaction pi(-)p --> pi(+)pi(-)pi(-)pi(0)pi(0)p has been performed. The data show b(1)pi decay of the spin-exotic states pi(1)(1600) and pi(1)(2000). Three isovector 2(-+) states were seen in the omegarho(-) decay channel. In addition to the well known pi(2)(1670), signals were also observed for pi(2)(1880) and pi(2)(1970).

Journal Article↗

PubMed2005

[Diverticula of the appendix and their complications: value of sonography (review of 21 cases)].

PURPOSE: Diverticulosis is defined by the presence of diverticula along any segment of the GI tract. Diverticulosis and its associated complications may involve the appendix. The imaging and histological findings of 21 cases of diverticulitis of the appendix are reviewed. MATERIALS AND METHODS: Sonography, because of its high spatial resolution, is an ideal imaging technique to diagnose diverticulitis of the appendix. RESULTS: Similar to diverticulosis of the large bowel, diverticula of the appendix correspond to pseudo-diverticula composed of mucosa and sub mucosa herniating through the muscular layer. Chronic inflammatory changes affect the surrounding appendicular wall, as confirmed by histological examination. Clinical symptoms range from chronic right lower quadrant abdominal pain to acute appendicitis and even peritonitis. CONCLUSION: Based on this retrospective analysis of 21 cases, it is possible to describe the specific and sensitive imaging findings for diagnosis of simple and complicated forms of diverticulitis of the appendix. Surgery is the treatment of choice because of the high risk of perforation.

Appendix↗

PubMed2005

The recombinant rat glucagon-like peptide-1 receptor, expressed in an alpha-cell line, is coupled to adenylyl cyclase activation and intracellular calcium release.

The glucagon-like peptide-1 (GLP-1) receptor is expressed on alpha-cells, though its functional significance is unknown. The endogenous beta-cell GLP-1 receptor is coupled to adenylyl cyclase, cell depolarization, activation of voltage-dependent Ca2+ channels (VDCC) and extracellular Ca2+ influx (Lu et al., 1993 b). In contrast, the signaling pathways of the GLP-1 receptor in alpha-cells are poorly understood. To determine the signaling mechanisms of the alpha-cell GLP-1 receptor, we established a stable pancreatic islet alpha-cell line expressing the recombinant rat GLP-1 receptor (INR1-SF2), using INRl-G9 cells. These INRl-G9 cells do not express endogenous GLP-1 receptor. In INR1-SF2 cells, GLP-1 bound to the recombinant receptor (Kd = 0.9 nM) and increased cAMP (ED50 = 0.6 nM). GLP-1 increased the free cytosolic Ca2+ ([Ca2+]i) (ED50 = 50 nM) by release from intracellular stores, but did not affect INR1-SF2 cell phosphoinositol turnover. Despite expressing VDCC, the INR1-SF2 cells were not depolarized by GLP-1, even in the presence of glucose. This contrasts with the depolarizing action of GLP-1 in beta-cells in the presence of glucose (Lu et al., 1993 b). This study establishes that a single GLP-1 receptor species can mediate the effects of GLP-1 through multiple signaling pathways, including the adenylyl cyclase system and intracellular Ca2+ release, in an alpha-cell type. Furthermore, since GLP-1 is unable to cause cellular depolarization or activate VDCC in INR1-SF2 cells, these data suggest that glucose-induced membrane depolarization may be crucial for GLP-1 to further activate VDCC and potentiate glucose-stimulated insulin release in beta-cells. Finally this study describes a cell line that can be used as a model system for evaluation of GLP-1 signaling in alpha-cells.

Adenylyl Cyclases↗

PubMed2004

Quantitative assessment of early healing of intramembranous and endochondral autogenous bone grafts using micro-computed tomography and Q-win image analyzer.

Micro-computed tomography (microCT) is a new tool to image and quantify trabecular bone. The aim of this study is to compare the two measurement methods when evaluating the early healing of intramembranous (IM) and endochondral (EC) autogenous bone grafts using micro-computed tomography and Q-win computer image analyzer. Twelve critical size (15 mm x 10 mm) defects were created in rabbit mandibles bilaterally. Six defects were grafted with autogenous EC bone; six defects were grafted with autogenous IM bone. Three weeks post-surgery, the defects were retrieved for microCT imaging analysis and histological evaluation. Results showed a significant correlation (r = 0.96, P < 0.0001) between microCT and Q-win in measuring the volume of new bone and graft bone in the mandibular defects after 3 weeks of early healing. There were distinct differences between IM bone and EC bone grafts in 2D and 3D features of graft bone maintenance as well as new bone formation. MicroCT imaging is a non-destructive, fast and precise procedure that allows for quantitative evaluation of the early healing of IM and EC autogenous bone grafts in membranous bone defects.

Analysis of Variance↗

PubMed2004

Identification of a glycosylation site in the woodchuck hepatitis virus preS2 protein and its role in protein trafficking.

The middle surface antigen (M-sAg) of hepadnaviruses is one of three envelope proteins that share a common C-terminal S domain. M-sAg contains the preS2 domain in addition to the S region. The preS2 region of woodchuck hepatitis virus (WHV) contains a potential glycosylation site Asn-Gln-Thr at amino acid (aa) positions 3-5. In this study, we mutated this site by site-directed mutagenesis and confirmed that glycosylation occurs here. In in vitro translation assays, the mutation Thr to Asn at aa 5 significantly impaired glycosylation of M-sAg. The mutated M-sAg formed abnormal clustered structures in transfected cells as determined by immunofluorescent staining. Confocal microscopic analysis showed that an enrichment of this glycosylation-deficient protein in the Golgi apparatus occurred, which is not typical for the wild-type protein. These results are consistent with earlier findings that incorrect glycosylation of viral proteins may interfere with virus assembly.

Amino Acid Sequence↗

PubMed2003

Interstitial collagenase activity stimulates the formation of actin rings and ruffled membranes in mouse marrow osteoclasts.

Interstitial collagenase activity stimulates bone resorption by mouse marrow osteoclasts [1]. Here, we show that collagenase activity promotes bone resorption by activating adherent osteoclasts to resorb bone. Inhibition of interstitial collagenase activity, either with peptidomimetic hydroxymates or with a specific anti-interstitial collagenase inhibiting antibody, reduced bone resorption by 73-92%. Equal numbers of osteoclasts adhered to bone in the presence of collagenase inhibitors and osteoclast survival was unaffected. In contrast, formation of actin rings and polarization of the vacuolar-H+-ATPase (V-ATPase) to ruffled membranes, two indicators of osteoclast activation, were decreased by inhibiting collagenase activity and stimulated in the presence of cleaved or heat-denatured type I collagen in proportion to increases and decreases of bone resorptive activity. Addition of excess recombinant osteoprotegerin-ligand to cultures did not restore bone resorption in the presence of interstitial collagenase inhibitors. These data support the hypothesis that cleaved collagen stimulates osteoclastic bone resorption by triggering cytoskeletal reorganization and transport of V-ATPase from cytoplasmic stores to ruffled membranes.

Actins↗

PubMed2003

Microarchitecture of rabbit mandibular defects grafted with intramembranous or endochondral bone shown by micro-computed tomography.

The aim of this study was to assess the integration of intramembranous and endochondral autogeneous bone grafts into membranous bony defects, by analysing the microarchitectural changes of the grafted bone 3 months after grafting. Twelve critical size defects (15 x 10mm) were created in rabbit mandibles bilaterally. Six defects on the right side of the mandible were grafted with autogenous endochondral bone, and six on the left were grafted with intramembranous bone. Three months later, the defects were retrieved for imaging with micro-computed tomography (Micro-CT) and for radiographic and histological evaluation. Micro-CT showed that intramembranous bone gave more bone volume a larger, trabecular number and trabecular thickness (P<0.001), and that endochondral bone had more trabecular separation (P<0.001). These findings indicate that intramembranous bone grafts integrate better than endochondral bone grafts in three-dimensions when they are grafted into membranous bony defects.

Animals↗

PubMed2003

Molecular genetic and biochemical analysis of woodchuck (Marmota monax) MHC class I polymorphism.

The woodchuck (Marmota monax) is an animal model that is used in the study of human hepatitis B virus ( HBV ) infection. A knowledge of woodchuck MHC class I (Mamo-I) genes and gene products is therefore essential for understanding the antigen-specific T-cell responses in this animal model. A number of Mamo-I genes have been identified by molecular cloning and sequencing. However, the allelic nature of these genes has not been proven by classical genetics like the segregation analysis in families. In this study, we analyzed the allelic diversity of Mamo-I in two three-generation woodchuck families including 15 members by sequencing of Mamo-I genes and immunoblotting of Mamo-I proteins after one-dimensional isoelectric focusing (1D-IEF). In addition to four published Mamo-I alleles, six new alleles that belonged to the same locus as the known Mamo-I alleles (Mamo-A) were found within the two woodchuck families. A typical Mendelian segregation of Mamo-I gene and antigens was observed in the families studied. For simple and rapid detection of allelic variability of Mamo-I gene, a typing method based on the detection of PCR products amplified by sequence specific primers (SSP) has been developed and tested in 41 unrelated animals. The most prevalent allele was Mamo-A*01 with a frequency of 21.9% followed by Mamo-A*07 (12.2%). Our study established Mamo-A as a classical MHC class I locus by the polymorphic and allelic nature of Mamo-I gene in the woodchuck.

Amino Acid Sequence↗

PubMed2003

Molecular characterization of CD28 and cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4) of woodchuck (Marmota monax).

Eastern woodchuck (Marmota monax) became an important animal model to study the immunological processes in hepatitis B virus infection. To facilitate further study of T-cell responses in this model, we cloned and sequenced the cDNAs of Woodchuck CD28 and cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4), which play important roles for the regulation of T-cell activation by delivering the costimulation signals. According to the deduced amino-acid sequences, Woodchuck CD28 showed a similarity of 70% to 80% to its mammalian homologues. Woodchuck CTLA-4 has a higher similarity of 74% to 85% to corresponding mammalian CTLA-4 molecules. The strict conservation of critical amino-acid residues like cystein and asparagine residues in Woodchuck CD28 and CTLA-4 suggests that both molecules may structurally resemble their human or mouse homologues. A hexapeptide motif, MYPPPY, which has been supposed to be essential for the interaction with CD80, is present in both Woodchuck CD28 and CTLA-4. The cloned cDNAs of Woodchuck CD28 and CTLA-4 were placed under the control of the cytomegalovirus (CMV) promoter of the mammalian expression vector pcDNA3. Both proteins were expressed and detected by respective crossreactive antibodies in transiently transfected mammalian cells. By immunohistochemical staining with these antibodies, CD28 and CTLA-4 were also detected on cultured woodchuck peripheral blood lymphocytes. The molecular characterization of Woodchuck CD28 and CTLA-4 will facilitate studies on the T-cell response to hepadnavirus in the woodchuck model.

Animals↗

PubMed2003

Pre-neutralization of C5a-mediated effects by the monoclonal antibody 137-26 reacting with the C5a moiety of native C5 without preventing C5 cleavage.

Complement C5a is aetiologically linked to inflammatory tissue damage in conditions like septicaemia, immune complex diseases and ischaemia-reperfusion injury. We here describe a monoclonal antibody (mAb), 137-26, that binds to the C5a moiety of human C5 and neutralizes the effects of C5a without interfering with C5 cleavage and the subsequent formation of lytic C5b-9 complex. Mouse anti-human C5 mAbs were generated and the reactivity with C5 and C5a was detected by ELISA and surface plasmon resonance. The inhibition of C5a binding to C5a receptor was studied using a radioligand binding assay. The effects of the antibody on C5a functions were examined using isolated neutrophils and a novel human whole blood model of inflammation. Haemolytic assays were used to study the effect on complement-mediated lysis. mAb 137-26 reacted with both solid- and solution-phase C5 and C5a in a dose-dependent manner with high affinity. The antibody competed C5a binding to C5a receptor and inhibited C5a-mediated chemotaxis of neutrophils. Furthermore, the antibody effectively abrogated complement-dependent E. coli-induced CD11b up-regulation and oxidative burst in neutrophils of human whole blood. mAb 137-26 was more potent than a C5a receptor antagonist and a previously described anti-C5a antibody. mAb 137-26 did not inhibit complement-mediated lysis, nor did it activate complement itself. Together, mAb 137-26 binds both the C5a moiety of native C5 and free C5a, thereby effectively neutralizing the biological effects of C5a. The antibody may have therapeutic potential in inflammatory diseases where C5a inhibition combined with an operative lytic pathway of C5b-9 is particularly desired.

Animals↗

PubMed2003

The infectivity of Plasmodium yoelii in different strains of mice.

We evaluated the effect of using Medium 199 alone and Medium 199 supplemented with 5% normal mouse serum, 5% fetal calf serum, 5% bovine serum albumin or 5% Albumax on Plasmodium yoelii sporozoite yield from infected mosquitoes and infectivity in BALB/c mice. The sporozoites yield, as well as their infectivity, was statistically lower (P = 0.0031) when unsupplemented Medium 199 was used to separate sporozoites from infected mosquitoes. Although Medium 199 supplemented with Albumax led to lower sporozoite yield (P < 0.0009), infectivity of the sporozoites was similar to those obtained with the other medium supplements. Because normal mouse serum supports good sporozoite infections and is also the supplement that can be used repeatedly in mice during multiple sporozoite injections without inducing anaphylaxis, we selected it to evaluate the infectivity of P. yoelii sporozoites in different strains of mice. After injecting mice with serial dilutions of sporozoites and detecting patent infections, we determined that the infective dose 50 (ID50) for BALB/c, C57Bl/6, A/J, and B10BR mice ranged between 4.9 and 10.6 sporozoites. The ID50 obtained for CD-1 mice (147 sporozoites) was significantly higher.

Animals↗

PubMed2002

Human marrow stromal cell therapy for stroke in rat: neurotrophins and functional recovery.

OBJECTIVE: To test the effect of i.v.-injected human bone marrow stromal cells (hMSC) on neurologic functional deficits after stroke in rats. METHODS: Rats were subjected to transient middle cerebral artery occlusion and IV injected with 3 x 10(6) hMSC 1 day after stroke. Functional outcome was measured before and 1, 7, and 14 days after stroke. Mixed lymphocyte reaction and the development of cytotoxic T lymphocytes measured the immune rejection of hMSC. A monoclonal antibody specific to human cellular nuclei (mAb1281) was used to identify hMSC and to measure neural phenotype. ELISA analyzed neurotrophin levels in cerebral tissue from hMSC-treated or nontreated rats. Bromodeoxyuridine injections were used to identify newly formed cells. RESULTS: Significant recovery of function was found in rats treated with hMSC at 14 days compared with control rats with ischemia. Few (1 to 5%) hMSC expressed proteins phenotypic of brain parenchymal cells. Brain-derived neurotrophic factor and nerve growth factor significantly increased, and apoptotic cells significantly decreased in the ischemic boundary zone; significantly more bromodeoxyuridine-reactive cells were detected in the subventricular zone of the ischemic hemisphere of rats treated with hMSC. hMSC induced proliferation of lymphocytes without the induction of cytotoxic T lymphocytes. CONCLUSION: Neurologic benefit resulting from hMSC treatment of stroke in rats may derive from the increase of growth factors in the ischemic tissue, the reduction of apoptosis in the penumbral zone of the lesion, and the proliferation of endogenous cells in the subventricular zone.

Animals↗

PubMed2002

Electrochemical behavior of Au colloidal electrode through layer-by-layer self-assembly.

Electrodes formed by Au colloidal nanoparticles have been obtained by layer-by-layer self-assembly using 1,6-hexanedithiol as cross-linkers. Cyclic voltammograms show that the peak-to-peak separation decreases as the number of Au colloidal layers increases. After seven layers of Au colloidal particles have been deposited, the multilayer electrodes have the electrochemical properties of metallic Au and show ideal microelectrode behavior. An equivalent circuit for the electrochemical impedance spectroscopy was established to model the working electrode. It is evident that by increasing the layer number of Au colloidals, the interfacial electron transfer is promoted, implying the electron-transfer process changes from a kinetically limited process to a diffusionally limited process.

Colloids↗

PubMed2002

Modelling the cost-effectiveness of sentinel lymph node mapping and adjuvant interferon treatment for stage II melanoma.

Clinical studies have demonstrated that high dose adjuvant interferon therapy improves disease-free and overall survival among high risk (stage IIb and III) melanoma patients. Sentinel lymph node mapping (SLM) has been shown to accurately detect micrometastasis and may be used to identify higher risk stage II patients, who might benefit most from adjuvant interferon therapy. We modelled the cost-effectiveness of first testing with SLM and then treating with adjuvant interferon (IFN) therapy for stage II melanoma. We used a decision analytical model to compare four strategies for stage II patients after surgical excision of their melanoma: (1) treat all with low dose IFN; (2) test first with SLM and then treat only those with positive micrometastasis with high dose IFN; (3) test first with SLM and treat positives with high dose IFN and negatives with low dose IFN (test and treat appropriately); and (4) surgery only. Treatment, toxicity, follow-up and relapse costs were included over a 5 year time period. The primary outcome was cost per quality-adjusted relapse-free life year saved. Our analysis shows that, compared with the current surgery-only strategy, all three treatment strategies provide incremental benefits. The test and treat appropriately strategy is the most effective, with an incremental improvement of 0.64 quality-adjusted life-years (QALY). The cost-effectiveness of test and treat some with high dose IFN compared with the surgery-only strategy is $18,700/QALY. The test and treat appropriately strategy is also cost-effective compared with test and treat some at $31,100/QALY. In conclusion appropriate dosing of IFN therapy based on the results of SLM is a cost-effective strategy for stage II melanoma patients.

Adjuvants, Immunologic↗