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Biomedical subjects

S Muller

Publications and source records attributed to S Muller.

At least 19 recordsLinked to original sources
PubMed2001

The Plasmodium falciparum bifunctional ornithine decarboxylase, S-adenosyl-L-methionine decarboxylase, enables a well balanced polyamine synthesis without domain-domain interaction.

In the human malaria parasite Plasmodium falciparum (Pf), polyamines are synthesized by a bifunctional enzyme that possesses both ornithine decarboxylase (ODC) and S-adenosyl-l-methionine decarboxylase (AdoMetDC) activities. The mature enzyme consists of the heterotetrameric N-terminal AdoMetDC and the C-terminal dimeric ODC, which results in the formation of a heterotetrameric complex. For the native bifunctional protein a half-life longer than 2 h was determined, which is in contrast to the extreme short half-life of its mammalian monofunctional counterparts. The biological advantage of the plasmodial bifunctional ODC/AdoMetDC might be that the control of polyamine synthesis is achieved by only having to regulate the abundance and activity of one protein. An interesting feature in the regulation of the bifunctional protein is that putrescine inhibits PfODC activity approximately 10-fold more efficiently than the mammalian ODC activity, and in contrast to the mammalian AdoMetDC the activity of the PfAdoMetDC domain is not stimulated by the diamine. To analyze post-translational processing, polymerization, and domain-domain interactions, several mutant proteins were generated that have single mutations in either the PfODC or PfAdoMetDC domains. The exchange of amino acids essential for the activity of one domain had no effect on the enzyme activity of the other domain. Even prevention of the post-translational cleavage of the AdoMetDC domain or ODC dimerization and thus the interference with the folding of the protein hardly affected the activity of the partner domain. In addition, inhibition of the activity of the PfODC domain had no effect on the activity of the PfAdoMetDC domain and vice versa. These results demonstrate that no domain-domain interactions occur between the two enzymes of the bifunctional PfODC/AdoMetDC and that both enzymatic activities are operating as independent catalytic sites that do not affect each other.

Adenosylmethionine Decarboxylase↗
PubMed2001

A novel early estrogen-regulated gene gec1 encodes a protein related to GABARAP.

We have isolated, in guinea-pig endometrial cells, an estrogen-induced 1.8 kb RNA called gec1. Screening of a guinea-pig genomic library led to identification of gec1 gene consisting of 4 exons and 3 introns. Exon 1 contains the 5'UTR and the ATG initiation codon. A guinea-pig gec1 cDNA was obtained by 5'-RACE. The 351 bp coding sequence shares 76.8% identity with that of the human GABARAP 924 bp cDNA while UTRs of the two cDNAs differ. A gec1 probe from the 3'UTR revealed a 1.9 kb mRNA in human tissues and a human GEC1 cDNA was isolated from placenta. Its coding sequence shares 93 and 79% identity with that of guinea-pig gec1 and human GABARAP, respectively. The human and guinea-pig GEC1 proteins have 100% identity. GEC1 and GABARAP proteins have 87% identity and N terminus featuring a tubulin binding motif. Thus, estrogen-regulated gec1 is a new gene which could encode a microtubule-associated protein.

3' Untranslated Regions↗
PubMed2001

Structure of antibody-bound peptides and retro-inverso analogues. A transferred nuclear Overhauser effect spectroscopy and molecular dynamics approach.

The three-dimensional structures of the two L-peptides, H-CGGIRGERA-OH, called L(A), and H-CGGIRGERG-OH, called L(G), corresponding or close to the IRGERA sequence present in the C-terminal region (residues 130-135) of histone H3, and their retro-inverso analogues HO-mAreGriGGC-NH2, called RI(mA), and HO-mGreGriGGC-NH2, called RI(mG), have been studied by two-dimensional 1H NMR and molecular dynamics calculations in association with a monoclonal antibody generated against L(A). At 25 degrees C, the affinity constants of the monoclonal antibody with respect to RI(mA) and RI(mG) were 75- and 270-fold higher than those measured with the homologous L(A) and L(G) peptides, respectively. Due to the spontaneous epimerization of the mA malonic residue, RI(mA) gave rise to two sets of resonances. With regard to the NH amide region, one set was similar to that for RI(mG) while the second was similar to those for the parent L-peptides L(A) and L(G). The antibody-bound conformations of the two couples of L- and retro-inverso peptides have been analyzed using molecular modeling calculations based on the transferred NOE interproton distances. Folded structures appeared in both cases with a type II' beta-turn in the parent GGIR sequence and a type I' beta-turn in the retro-inverso reGr sequence.

Antibodies, Monoclonal↗
PubMed2001

The bare skin and the nose as non-invasive routes for administering peptide vaccines.

Among the different technologies currently tested for the development of novel vaccines, synthetic peptides represent a promising option, since they are chemically pure and induce immune responses of predetermined specificity. Furthermore, they can be replaced with pseudopeptides or peptide mimetics that contain changes in the amide bond, resulting in more stable and immunogenic molecules. Administration of peptide vaccines via non-invasive routes, such as the nose or the bare skin, allows the efficient uptake of antigen by antigen-presenting cells, which are abundant in the associated lymphoid tissues, ensuring the induction of effective systemic and mucosal immune responses. Using non-invasive routes could be advantageous for vaccination programs in third-world countries, since vaccine administration is simple, painless and economical. In this review, we discuss and present some preliminary data on the advantages of synthetic peptides and peptidomimetics as candidate vaccines, and their potential for administration via the skin and the nose.

Administration, Cutaneous↗
PubMed2001

DNA-bound transcription factor complexes analysed by mass-spectrometry: binding of novel proteins to the human c-fos SRE and related sequences.

Transcription factors control eukaryotic polymerase II function by influencing the recruitment of multiprotein complexes to promoters and their subsequent integrated function. The complexity of the functional 'transcriptosome' has necessitated biochemical fractionation and subsequent protein sequencing on a grand scale to identify individual components. As a consequence, much is now known of the basal transcription complex. In contrast, less is known about the complexes formed at distal promoter elements. The c-fos SRE, for example, is known to bind Serum Response Factor (SRF) and ternary complex factors such as Elk-1. Their interaction with other factors at the SRE is implied but, to date, none have been identified. Here we describe the use of mass-spectrometric sequencing to identify six proteins, SRF, Elk-1 and four novel proteins, captured on SRE duplexes linked to magnetic beads. This approach is generally applicable to the characterisation of nucleic acid-bound protein complexes and the post-translational modification of their components.

Amino Acid Sequence↗
PubMed2001

High tumor grade in salivary gland mucoepidermoid carcinomas and loss of expression of transforming growth factor beta receptor type II.

BACKGROUND: Mucoepidermoid carcinoma (MEC) of salivary glands is a malignant, locally aggressive neoplasm with metastatic potential. The clinical course is usually dependent on histology; however, low-grade carcinomas can result in metastases and tumor-related death. Transforming growth factor beta1 (TGF-beta1) is a potent cytokine that affects growth inhibition of various cells and stimulates extracellular matrix production and angiogenesis. Loss of TGF-beta receptor type II (TGF-beta RII) expression has been related to resistance of TGF-beta1-mediated growth control and tumor progression. In this study, we correlate MEC tumor grade with expression of TGF-beta1 and TGF-beta RII. DESIGN: Immunohistochemical staining was performed on 16 MEC specimens for activated forms of TGF-beta1 and TGF-beta RII. The percentage of cells in which staining yielded positive findings for activated TGF-beta1 and TGF-beta RII was correlated with tumor grade. RESULTS: Activated TGF-beta1 was detected in 16 specimens (100%) of MEC and showed strong positive and diffuse staining. Predominately cytoplasmic staining of TGF-beta1 was seen in salivary gland ducts, stroma, and endothelial cells. There was an inverse correlation between tumor grade and loss of expression of TGF-beta RII. All low-grade MEC tumors yielded positive staining results, whereas only one case of intermediate-grade MEC had TGF-beta RII expression. No high-grade MEC showed TGF-beta RII expression. CONCLUSIONS: Loss of expression of TGF-beta RII correlates with tumor grade. The localization of activated TGF-beta1 within neoplastic epithelium, tumor-associated stroma, and endothelium suggests that it might play a role in the stromal proliferation and/or angiogenesis associated with MEC.

Adolescent↗
PubMed2001

Heterotopic neuroglial tissue causing airway obstruction in the newborn.

BACKGROUND: Heterotopic neuroglial (brain) tissue is a rare cause of airway obstruction in newborns. Fewer than 30 cases have been reported in the English literature. Brain heterotopias can mimic more common congenital anomalies of the head and neck. OBJECTIVE: To review our experience in the diagnosis and treatment of children with heterotopic pharyngeal neuroglial tissue. DESIGN: Case series. SETTING: Tertiary care children's hospital. PATIENTS: Four newborns with airway obstruction caused by heterotopic neuroglial tissue. RESULTS: All patients were infants (3 full-term girls and a 32 weeks' gestation boy) who had airway obstruction in the newborn period. All patients underwent preoperative computed tomography and magnetic resonance imaging, which revealed a heterogeneous mass involving the pharynx, neck, and parapharyngeal space. Bony deformities of the skull base and mandible were present in all patients, although intracranial connection was absent. Multiple surgical procedures were performed in all 4 patients. Tracheotomy was performed in 2 patients, gastrostomy tube placement was required in 3, and a nasopharyngeal tube was used in 1. Combined cervicofacial and transoral approaches were used for resection, preserving vital structures. Histopathologic evaluation revealed mature glial tissue and choroid plexus-like structures. CONCLUSIONS: Heterotopic neuroglial tissue must be considered in the differential diagnosis of airway obstruction in the newborn. Management is surgical resection, with attention to vital structures and function-analogous to surgery for lymphangioma. Multiple surgical procedures might be necessary in the treatment of these patients.

Airway Obstruction↗
PubMed2001

[Severe autoimmune immunoglobulin A hemolytic anemia in a 10-month-old infant].

CASE REPORT: A ten-month-old boy presented with a severe auto-immune hemolytic anemia. Direct antiglobin test was positive only for IgA class autoantibodies. He recovered with a high dose corticosteroid treatment. CONCLUSION: IgA class autoantibodies should be searched for in the case of a high suspicion of auto-immune hemolytic anemia with negative direct antiglobin test for IgG and complement. Corticosteroid treatment is most often successful.

Anemia, Hemolytic, Autoimmune↗
PubMed2001

Palliative surgical debulking in malignant mesothelioma. Predictors of survival and symptom control.

OBJECTIVE: Malignant mesothelioma (MM) typically presents at an advanced stage. In the UK surgical intervention has been mostly reserved for tissue diagnosis or chemical pleurodesis. However, the role of debulking surgery in symptom control has not been fully explored. METHODS: In a prospective cohort study, 51 consecutive patients presenting with MM underwent palliative surgical debulking for symptomatic relief (all patients presented with dyspnoea, 39 also had pain and two had a co-existing pleural empyema). Patients with early disease who underwent extrapleural pneumonectomy were excluded. The treatment aims were pleural drainage, lung re-expansion, pleurodesis and pleural debulking for symptom control. If the lung re-expanded after drainage of the effusion a subtotal parietal pleurectomy was performed via Video Assisted Thoracic Surgery (VATS). If the lung remained entrapped, a parietal and visceral decortication using VATS or thoracotomy was performed. The changes in subjective dyspnoea and pain scores were recorded at 6 weeks and 3, 6 and 12 months after surgery. Prognostic factors were analyzed to determine their influence on survival and symptom control. RESULTS: VATS pleurectomy was possible in 17 patients (34%), whilst decortication was required in the remainder (three by VATS and 31 by thoracotomy). Median postoperative stay was 7 days (range 2-17) with 30-day mortality of 7.8% (four of 51 patients). Morbidity included postoperative empyema in two patients (4%) and prolonged air-leak in five (9.8%). Overall significant symptomatic benefit was obtained up to 3 months after surgery but subsequently increasing mortality offset these benefits. Epithelial cell type and absence of weight loss prior to surgery were found to predict longer survival and successful symptom control. CONCLUSIONS: Debulking surgery has a beneficial role in symptom control for unresectable MM. However, this surgery should be reserved for those patients who present with epithelial cell type and before significant loss of weight.

Adult↗
PubMed2001

Fusogenic activity of vesicular stomatitis virus glycoprotein plasmid in tumors as an enhancer of IL-12 gene therapy.

We have characterized the fusogenic activity of a plasmid expression system encoding vesicular stomatitis virus G protein (VSVG) in vitro and in vivo. Over 70% of murine colon and renal carcinoma cells (MC38 and Renca, respectively) transfected with VSVG plasmid in vitro fused and formed polykaryons upon incubation with pH 5.5 media. Using a plasmid expression system encoding VSVG and bacterial green fluorescent protein (GFP) formulated in a polyvinyl pyrrolidone (PVP) delivery system, diffusion of GFP throughout the VSVG-induced syncytia was shown in vivo in MC38 and Renca tumors. Moreover, tumor-bearing mice showed tumor growth inhibition following in vivo transfection with VSVG plasmid at an optimal dose of 48 microg. We have previously shown that direct injection of interleukin -12 (IL -12) plasmid complexed with PVP into tumors induces a strong immune response. In the current study, we assessed the ability of VSVG to elicit an antitumor response by enhancing cytokine gene delivery within the tumor mass. Tumor-bearing mice treated intratumorally with both VSVG/PVP and IL-12/PVP (48 and 24 microg, respectively) showed increase in tumor rejection when compared to IL- 12 plasmid alone (75% vs. 50%, respectively). These data suggest that VSVG gene therapy can be used in combination with other therapeutic genes to induce an antitumor response in vivo by enhancing the expression of the gene of interest.

Animals↗
PubMed2001

Immunization onto bare skin with heat-labile enterotoxin of Escherichia coli enhances immune responses to coadministered protein and peptide antigens and protects mice against lethal toxin challenge.

In this study, the potential of the bare skin as a non-invasive route for vaccination was examined. Following application of heat-labile enterotoxin (LT) of Escherichia coli onto bare skin of BALB/c mice, strong serum anti-LT antibody responses were observed, and mucosal immunoglobulin A (IgA) and IgG antibodies were measured in vagina washes. In addition, LT enhanced the serum and mucosal antibody and proliferative T-cell responses to the model protein antigen beta-galactosidase (beta-gal) when coadministered onto bare skin, highlighting its potential to exert an adjuvant effect. When a peptide representing a T-helper epitope (aa 307-319) from the haemagglutinin of influenza virus was applied onto bare skin with LT or cholera toxin (CT), it primed effectively peptide- and virus-specific T cells, as measured in vitro by the interleukin-2 (IL-2) secretion assay. LT was shown to be as immunogenic as CT. Binding activity to GM1 gangliosides was essential for effective induction of anti-CT serum and mucosal antibody responses. Finally, mice immunized onto bare skin with LT were protected against intraperitoneal challenge with a lethal dose of the homologous toxin. These findings give further support to a growing body of evidence on the potential of skin as a non-invasive route for vaccine delivery. This immunization strategy might be advantageous for vaccination programmes in Third World countries, because administration by this route is simple, painless and economical.

Adjuvants, Immunologic↗
PubMed2001

Stimulation of antiviral antibody response in SHIV-IIIB-infected macaques.

Three macaques infected with SHIV-IIIB and expressing the shared 1F7-idiotypic marker on antibodies against HIV-1 gp120, were injected intravenously with 1F7 monoclonal antibodies (MoAb). As controls, a SHIV-IIIB-infected macaque was injected with a HIV-unrelated mouse monoclonal isotype antibody (TEPC-183) and two healthy, noninfected macaques were injected with MoAb 1F7. 1F7-id-expressing antibodies against gp120-IIIB decreased in two of the three MoAb 1F7-treated macaques and then rebounded. Importantly, antibodies binding to envelope proteins of heterologous HIV-1 strains MN, CM, and SF2, which were low or not detectable before the MoAb 1F7 treatment, increased rapidly following MoAb inoculations in all three 1F7 MoAb treated macaques, but not in the macaque injected with control MoAb TEPC-183. Newly arising antibodies reacting with heterologous virus, i.e. HIV-1 gp120-MN, SF2, and CM did not express 1F7-id. Surprisingly, significant increases of antibodies were also observed in the 1F7-inoculated macaques' antibodies directed to non-HIV antigens (DNP, peptides and BSA). The noninfected control animals did not produce antibodies to these antigens despite MoAb 1F7 treatment. These data show that the MoAb 1F7 injections of chronically SHIV-IIIB-infected macaques resulted in idiotype-specific clonal suppression with broadening the antibody response to HIV envelope proteins.

Animals↗
PubMed2001

Murine models of systemic lupus erythematosus: B and T cell responses to spliceosomal ribonucleoproteins in MRL/Fas(lpr) and (NZB x NZW)F(1) lupus mice.

(NZB x NZW)F(1) and MRL/Fas(lpr) lupus mice present a similar phenotype with a spectrum of autoantibodies associated with very severe nephritis. It is thought, however, that in contrast to other lupus-prone mice such as MRL/Fas(lpr) mice, (NZB x NZW)F(1) mice do not generate autoantibodies to ribonucleoproteins (RNP) Sm/RNP. In this study, we demonstrate that contrary to previous reports, the autoimmune response directed against Sm/RNP antigens also occurs in NZB x NZW mice. CD4(+) T cells from unprimed 10-week-old NZB x NZW mice proliferate and secrete IL-2 in response to peptide 131-151 of the U1-70K protein, which is known to contain a T(h) epitope recognized by CD4(+) T cells from MRL/Fas(lpr) mice. Peptide 131-151, which was found to bind I-A(k) and I-E(k) class II MHC molecules, also bound both I-A(d) and I-E(d) molecules. This result led us to also re-evaluate longitudinally the anti-Sm/RNP antibody response in NZB x NZW mice. We found that 25-week-old mice do produce antibodies reacting with several small nuclear and heterogeneous nuclear (hn) RNP proteins, such as SmD1, U1-70K and hnRNP A2/B1 proteins. The fine specificity of these antibodies was studied with overlapping synthetic peptides. The same antigenically positive and negative peptides were characterized in MRL/Fas(lpr) and NZB x NZW mice in the three proteins. This new finding can help to understand the mechanisms involved in the development of the anti-Sm/RNP antibody response and, particularly, the role played by non-MHC genes in this autoimmune response.

Animals↗
PubMed2001

Sinonasal undifferentiated carcinoma with orbital invasion: report of three cases.

PURPOSE: To report three patients with sinonasal undifferentiated carcinoma (SNUC) that invaded the orbit. METHODS: Retrospective small case series. The clinical, radiographic, and pathologic features of three patients with SNUC were reviewed. RESULTS: Three patients with SNUC that invaded the orbit were evaluated. A biopsy was performed on the tumors, which were composed of small, hyperchromatic cells with numerous mitoses and areas of necrosis. Immunohistochemical staining was positive for cytokeratins AE1.3, epithelial membrane antigen, and neuron-specific enolase in all three tumors. Electron microscopic examination showed absence of neurosecretory granules and presence of basement membrane production. Two patients were treated with surgical resection and postoperative chemotherapy and/or radiation. One patient was treated with preoperative radiation and chemotherapy. CONCLUSIONS: Sinonasal undifferentiated carcinoma is a high-grade tumor that arises in the nasal and paranasal sinuses and may invade the orbit. SNUC should be distinguished from other small, round, blue cell tumors, in particular, esthesioneuroblastoma.

Adult↗
PubMed2001

Detection of nucleosome particles in serum and plasma from patients with systemic lupus erythematosus using monoclonal antibody 4H7.

OBJECTIVE: To develop a monoclonal antibody reagent that would react with nucleosomes but not directly with constituent double stranded DNA (dsDNA) or with histones. METHODS: Mice were immunized with highly purified chicken mononucleosomes and hybridomas employed to produce Mab that did not react with dsDNA or histones but still showed reactivity with nucleosomes. RESULTS: Murine monoclonal IgG antibody 4H7, generated from a mouse immunized with highly purified chicken erythrocyte nucleosomes, showed no direct ELISA reactivity with either dsDNA or isolated histones or with Sm and RNP antigens or combinations of any of these components. Mab 4H7 did show strong ELISA reactivity for chicken erythrocyte and calf thymus nucleosomes as well as for human leukocyte nucleosomes. The Mab did show strong ELISA reactions with peptides 1-25 of histone H2B and 1-21 of H3, which correspond to sequences known to be located at the surface of nucleosomes. We then measured relative serum levels of 4H7 reactive nucleosome antigen in 140 patients with systemic lupus erythematosus (SLE) in parallel with 50 non-SLE patients with other types of connective tissue disease and 92 healthy subjects. Occasional low levels of serum nucleosomal antigen were seen in 4 of 92 controls, but many patients with SLE (66/140) showed marked elevations of serum nucleosomal antigen. No difference was observed when serum or plasma samples were studied. A marked correlation (R = 0.401, p < 0.0001) was noted when disease activity score (SLEDAI) was plotted against optical density value measured with 4H7 in ELISA. Further, the levels of circulating nucleosomes were raised in SLE patients with very active central nervous system and renal involvement. CONCLUSION: Presence of nucleosome related antigen in sera from patients with SLE may provide insight into the sequence of disease related antigenic stimuli in active SLE.

Adult↗
PubMed2001

Effects of an angelica extract on human erythrocyte aggregation, deformation and osmotic fragility.

In Chinese traditional medicine, angelica is widely used for its known clinical effects of ameliorating blood microcirculation. But the mechanism of these beneficial effects still remains unclear. In this work the rheological behaviour of human erythrocytes treated by angelica was studied in vitro. Normal RBCs incubated with an angelica extract at different concentrations (5, 10 or 20 mg/ml) for 60 min at 37 degrees C and then their aggregation, deformation and osmotic fragility were measured with different recently developed optical techniques, namely Erythroaggregometer (Regulest, Florange, France), LORCA (Mechatronics, Amsterdam) and Fragilimeter (Regulest, Florange, France). Experimental results show that angelica (20 mg/ml) significantly decreased normal RBCs' aggregation speed (p<0.01) and could inhibit the hyperaggregability caused by dextran 500. However, the strength of normal RBCs aggregates were not influenced by angelica. When a calcium ionophore A23187 (1.9 microM) was used to harden cell membrane, angelica (20 mg/ml) could significantly (p<0.01) protect erythrocytes against the loss of their deformability even it had no effects on normal RBCs deformation. Finally angelica (5 and 10 mg/ml) decreased significantly (p<0.01) normal RBCs osmotic fragility. In conclusion angelica plays a rheologically active role on human erythrocytes, and this study suggests a possible mechanism for angelica's positive effects against certain cardiovascular diseases.

Asteraceae↗
PubMed2000

Intersubunit interactions in Plasmodium falciparum thioredoxin reductase.

The thioredoxin redox system is composed of the NADPH-dependent homodimeric flavoprotein thioredoxin reductase (TrxR) and the 12-kDa protein thioredoxin. It is responsible for the reduction of disulfide bridges in proteins such as ribonucleotide reductase and several transcription factors. Furthermore, thioredoxin is involved in the detoxification of hydrogen peroxide and protects the cell against oxidative damage. There exist two classes of TrxRs: the high M(r) and the low M(r) proteins. The well characterized Escherichia coli TrxR represents a member of the low M(r) class of proteins, whereas the mammalian, Caenorhabditis elegans, and Plasmodium falciparum proteins belong to the family of high M(r) proteins. The primary structure of these proteins is very similar to that of glutathione reductase and lipoamide dehydrogenase. However, the high M(r) TrxRs possess, in addition to their redox active N-terminal pair of cysteines, a pair of cysteine residues or a selenenylsulfide motif at their C terminus. These residues have been shown to be crucial for the reduction of thioredoxin. In this study we address the question whether the active site residues of P. falciparum TrxR are provided by one or both subunits. Differentially tagged wild-type and PfTrxR mutants were co-expressed in E. coli and the recombinant protein species were purified by affinity chromatography specific for the respective tags of the recombinant proteins. Co-expression of PfTrxR wild-type and mutant proteins resulted in the formation of three different protein species: homodimeric PfTrxR wild-type proteins, homodimeric mutant proteins, and heterodimers composed of one PfTrxR wild-type subunit and one PfTrxR mutant subunit. Co-expression of the double mutant PfTrxRC88AC535A with PfTrxR wild-type generated an inactive heterodimer, which indicates that PfTrxR possesses intersubunit active sites. In addition, the data presented possibly imply a coopertive interaction between both active sites of PfTrxR.

Animals↗