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Biomedical subjects

R E Smith

Publications and source records attributed to R E Smith.

At least 73 records · Page 4Linked to original sources
PubMed1998

Effect of polyamine analogues on hypusine content in JURKAT T-cells.

The availability of synthetic hypusine and deoxyhypusine has made it possible to develop analytical methods which allow for the measurement of these compounds in various tissues. The methods involve dansylation of extracts from the pellet remaining after perchloric acid precipitation of cell or tissue homogenates, followed by high-performance liquid chromatography. To demonstrate the utility of this approach, the impact of four polyamine analogues, N1,N11-diethylnorspermine (DENSPM), N1,N14-diethylhomospermine (DEHSPM), 1,6,12-triazadodecane [(4,5) triamine], and 1,7, 13-triazatridecane [(5,5) triamine], on hypusine levels in a human T-cell line (JURKAT) is evaluated. All four analogues are active in controlling cell growth and compete well with spermidine for the polyamine transport apparatus. After 144 h of exposure to JURKAT cells, DENSPM reduces putrescine to below detectable limits and spermidine to 10% of the level in control cells. The other three analogues diminish both putrescine and spermidine to below detectable limits. The effectiveness with which the compounds lower spermine levels is DENSPM > DEHSPM > (4,5) triamine > (5,5) triamine. The analogues decrease the activities of ornithine decarboxylase and S-adenosylmethionine decarboxylase in a similar fashion. Of the four polyamines, DENSPM and DEHSPM are potent at lowering intracellular hypusine levels after 144 h: 59 +/- 9% and 73 +/- 12% of control levels, respectively. The other two analogues have marginal effects.

Adenosylmethionine Decarboxylase↗
PubMed1998

The significance of hypersialylation of dipeptidyl peptidase IV (CD26) in the inhibition of its activity by Tat and other cationic peptides. CD26: a subverted adhesion molecule for HIV peptide binding.

The functionality of DPP-IV, purified from human placenta and isolated from CD4+/CD26+ T cells of noninfected and HIV-1-infected individuals, was investigated as to its ability to bind certain specific peptides. Using isoelectric focusing and the specificity of substrate-impregnated overlay membranes, we found that DPP-IV from term placenta and from T cells of HIV-infected individuals was significantly more sialylated compared with enzyme isozyme patterns of other tissues. We report here that (1) the number of isoforms of DPP-IV and extent of sialylation are critical to function and peptide binding; (2) the number of sialylated isoforms isolated from PBMCs increases significantly with age greater than 40 years; (3) hypersialylation by extreme anionic isoforms is highly associated with HIV infection and pathognomonic to remaining CD4+ cells in overt AIDS; and (4) highly sialylated DPP-IV is more significantly inhibited by Tat and cationic peptides. We conclude that hypersialylation of DPP-IV modifies surface charge of the CD26 antigen, promoting binding of HIV peptides through their cationic domains to the sialic acid residues of DPP-IV, and that certain HIV moieties are likely to engage this phenomenon as an auxiliary adhesion mechanism to fuse with cells. Furthermore, as a consequence of this occurrence, DPP-IV enzymatic activity can be significantly reduced, competitively.

Adolescent↗
PubMed1998

Hereditary spherocytosis, thrombocytosis, and chronic pulmonary emboli: a case report and review of the literature.

Thrombocytosis in post-splenectomy patients with hereditary spherocytosis (HS) is usually not attended by an increased risk of thrombosis. Review of the literature revealed HS in association with pulmonary thrombosis, portal vein thrombosis, and cerebral infarction in two brothers, TTP in an asplenic patient and a patient with corpora cavernosum thrombosis causing segmental priapism. We report a case of a 30-year-old white male with HS who presented with hemoptysis 29 years after splenectomy. Work-up revealed a hypercoagulable state with thrombocytosis and recurrent pulmonary emboli resulting in severe pulmonary hypertension, cor pulmonale, atrial flutter, and syncope.

Adult↗
PubMed1998

Heterogeneous suppression of experimentally induced colon cancer metastasis in rat liver lobes by inhibition of extracellular cathepsin B.

Metastatic rat colon cancer cells but not normal rat hepatocytes showed activity of cathepsin B on their plasma membranes. Activity was visualized in living cells with a new fluorogenic substrate, [Z-Arg]2-cresyl violet, and confocal microscopy. When these cancer cells were injected into the portal vein of rats, the animals developed tumors in the liver in a heterogeneous fashion. Three- to four-fold more tumors were found in the small caudate lobe than in the other three large lobes of the liver. Oral treatment with a selective water-soluble inhibitor of extracellular cathepsin B, Mu-Phe-homoPhe-fluoromethylketone, resulted in 60% reduction of the number of tumors and 80% reduction of the volume of tumors in the three large lobes whereas tumor development was not affected in the small caudate lobe. This study supports the conclusions that (a) extracellular cathepsin B plays a crucial but complex role in liver colonisation by rat colon carcinoma cells in vivo, (b) its selective inhibition suppresses tumor growth heterogeneously in the liver and (c) the caudate lobe of the liver is a relatively large risk factor for tumor development.

Amino Acid Chloromethyl Ketones↗
PubMed1998

Preservation of mucosal and systemic adjuvant properties of ISCOMS in the absence of functional interleukin-4 or interferon-gamma.

Adjuvants are a critical component of non-viable vaccine vectors, particularly for those to be used via mucosal routes. Although most adjuvants act by inducing local inflammatory responses, the molecular basis of many of these effects is unclear. Here we have investigated whether interleukin-4 (IL-4) and interferon-gamma (IFN-gamma) are required for the induction of local and systemic immune responses by oral and parenteral administration of ovalbumin (OVA) in immune stimulating complexes (ISCOMS), a potent mucosal adjuvant vector. Our results show that after oral or systemic immunization with OVA ISCOMS, IL-4 knockout (IL4KO) and IFN-gamma receptor knockout (IFN-gamma RKO) mice develop an entirely normal range of immune responses including delayed-type hypersensitivity (DTH), serum immunoglobulin G (IgG) antibodies, T-cell proliferation and cytokine production, class I major histocompatibility complex (MHC)-restricted cytotoxic T lymphocyte (CTL) activity and intestinal IgA antibodies. These responses were of a similar magnitude to those found in the wild-type mice, indicating that the immunogenicity of ISCOMS is not influenced by the presence of IL-4 or IFN-gamma and emphasizing the potential of ISCOMS as widely applicable mucosal adjuvants.

Adjuvants, Immunologic↗
PubMed1998

Immune stimulating complexes as mucosal vaccines.

There is a need for non-living adjuvant vectors that will allow a full range of local and systemic immune responses to orally administered purified antigens. Here we describe our experience with lipophilic immune-stimulating complexes (ISCOMs) containing the saponin adjuvant Quil A. When given orally, ISCOMs containing the model protein antigen ovalbumin (OVA) induce a wide range of systemic immune responses, including Th1 and Th2 CD4-dependent activity, serum IgG antibodies and class I MHC-restricted cytotoxic T cell responses. In addition, there is local production of secretory IgA antibodies in the intestine itself, as well as priming of CD4 and CD8 T cell responses in the draining lymphoid tissues. Preliminary results indicate that the mucosal adjuvant properties of ISCOMs may reflect their ability to deliver antigen combined with the pro-inflammatory properties of Quil A in a particulate form. Of the many inflammatory mediators induced, interleukin-12, derived from dendritic cells and/or macrophages, appears to be of central importance. These results indicate that ISCOMs may prove to be useful mucosal vaccine vectors with functions which are distinct from existing vectors of this type.

Animals↗
PubMed1998

Rheumatoid diseases.

Explore the source record for details and available documents.

Anti-Inflammatory Agents↗
PubMed1998

TNF and IL-6 mediate MIP-1alpha expression in bleomycin-induced lung injury.

Previously, macrophage inflammatory protein-1alpha (MIP-1alpha), a member of the C-C chemokine family, has been implicated in bleomycin-induced pulmonary fibrosis, a model of the human disease idiopathic pulmonary fibrosis. Neutralization of MIP-1alpha protein with anti-MIP-1alpha antibodies significantly attenuated both mononuclear phagocyte recruitment and pulmonary fibrosis in bleomycin-challenged CBA/J mice. However, the specific stimuli for MIP-1alpha expression in the bleomycin-induced lesion have not been characterized. In this report, two mediators of the inflammatory response to bleomycin, tumor necrosis factor (TNF) and interleukin-6 (IL-6), were evaluated as putative stimuli for MIP-1alpha expression after bleomycin challenge in CBA/J mice. Elevated levels of bioactive TNF and IL-6 were detected in bronchoalveolar lavage (BAL) fluid and lung homogenates from bleomycin-treated CBA/J mice at time points post-bleomycin challenge, which precede MIP-1alpha protein expression. Treatment of bleomycin-challenged mice with soluble TNF receptor (sTNFr) or anti-IL-6 antibodies significantly decreased MIP-1alpha protein expression in the lungs. Furthermore, normal alveolar macrophages secreted elevated levels of MIP-1alpha protein in response to treatment with TNF plus IL-6 or bleomycin plus IL-6, but not TNF, bleomycin, or IL-6 alone. Finally, leukocytes recovered from the BAL fluid of bleomycin-challenged mice secreted higher levels of MIP-1alpha protein, compared to controls, when treated with TNF alone. Based on the data presented here, we propose that TNF and IL-6 are part of a cytokine network that modulates MIP-1alpha protein expression in the profibrotic inflammatory lesion during the response to intratracheal bleomycin challenge.

Animals↗
PubMed1997

Functional conservation of HTLV-1 rex balances the immune pressure for sequence variation in the rex gene.

Naturally occurring mutations in Human T-cell Leukemia Virus Type 1 (HTLV-1) Tax protein lead to loss of recognition by cytotoxic T-lymphocytes. Most of these mutations also abolish or severely impair the transactivation function of Tax. Ninety percent of the rex gene, which encodes the viral regulator of mRNA splicing (Rex), overlaps with the tax gene. In this paper, we report that four previously described point mutations in tax that abolished CTL recognition and activity did not alter either the dimerisation function or the ability to export viral mRNA of the corresponding Rex proteins. Rex proteins containing two other amino acid changes were likewise functional. However, five Rex deletion mutants, predominantly but not exclusively found in HAM/TSP patients, had all lost these functions. We conclude that, although the Tax protein is subject to strong CTL-mediated selection, there are stronger functional constraints on amino acid variation in Rex. This may limit the variation in the tax/rex nucleotide sequence which results in immune evasion.

Cells, Cultured↗
PubMed1997

Ala-Pro-cresyl violet, a synthetic fluorogenic substrate for the analysis of kinetic parameters of dipeptidyl peptidase IV (CD26) in individual living rat hepatocytes.

A new type of fluorogenic substrates for proteases based on the leaving group cresyl violet has been synthesized. Cresyl violet is not fluorescent when amino acids or peptide groups are attached but becomes highly fluorescent after proteolytic liberation. Its fluorescence shows linearity with concentration and barely any fading. The properties of Ala-Pro-cresyl violet as substrate for dipeptidyl peptidase IV (DPPIV) (CD26) for localization and quantification of its activity in individual freshly isolated living rat hepatocytes were investigated using confocal microscopy, image analysis, and flow cytometry. DPPIV activity was localized exclusively in patches at plasma membranes likely being bile canalicular domains. Activity was analyzed quantitatively in individual cells by capturing series of images in time. Production of fluorescence was analyzed on the basis of the series of digital images and it appeared to be nonlinear with time. By calculation of the initial velocity at time zero, activity of DPPIV per individual hepatocyte was calculated. Cresyl violet-dependent fluorescence appeared in a similar way when cells were analyzed by flow cytometry. A dipeptide phosphonate inhibitor inhibited production of fluorescence competitively with a Ki of 7 microM. K(m) values in individual hepatocytes varied in the range of 6-22 microM depending on the individual rat from which the hepatocytes were obtained, whereas the Vmax varied in the range of 4-16 nU. K(m) and Vmax values per individual rat were inversely correlated indicating posttranslational regulation of the kinetic parameters of DPPIV. This relationship was lost when membrane fractions of the same hepatocyte suspensions were analyzed. It is concluded that cresyl violet-based protease substrates are the compounds of choice to localize and quantify protease activity in living cells and tissues.

Animals↗
PubMed1997

Chemical synthesis of 4-trifluoromethylumbelliferyl-alpha-D-N-acetylneuraminic acid glycoside and its use for the fluorometric detection of poorly expressed natural and recombinant sialidases.

When compared to bacterial or viral sialidases, eukaryotic sialidases are expressed at lower levels and frequently show poor specific activities. The identification and characterization of sialidases from eukaryotes have been slowed down due to the limited sensitivity of available sialidase substrates. Therefore, we chemically synthesized a fluorogenic compound, 4-trifluoromethylumbelliferyl-alpha-D-N-acetylneuraminic acid (CF3MU-Neu5Ac), and tested its use as a substrate for eight different sialidases, including enzymes from viral, bacterial, and eukaryotic sources. Kinetic analysis revealed CF3MU-Neu5Ac to be a very sensitive sialidase substrate. Furthermore, this substance proves to be perfectly suitable for the in vivo examination of sialidases and for the detection of recombinant sialidase by means of expression cloning.

Escherichia coli↗
PubMed1997

Acetylsalicylic-acid-containing drugs and nonsteroidal anti-inflammatory drugs available in Canada.

A large number of drugs containing acetylsalicylic acid (ASA) and nonsteroidal anti-inflammatory drugs (NSAIDs) are available by prescription and over the counter in Canada. The possibility of serious side effects and drug interactions is therefore high. The authors have compiled a comprehensive list of products containing these drugs from information supplied by pharmaceutical databases, independent marketing researchers and Health Canada's Drug Directorate. Physicians should ensure that additional ASA-containing drugs or NSAIDs are not inadvertently taken by patients, especially those receiving oral anticoagulant therapy or those with a qualitative platelet defect. Patients at risk should be cautioned to check with their physician before taking any new medication, even over-the-counter products.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed1997

Intensified regimen for advanced head and neck squamous cell carcinomas.

OBJECTIVE: To devise an intensified treatment regimen for patients with advanced, resectable head and neck squamous cell carcinomas. DESIGN: Phase I/II clinical trial consisting of perioperative cisplatin chemoradiotherapy, surgical resection, intraoperative radiotherapy, and postoperative cisplatin chemoradiotherapy. SETTING: The Ohio State University Comprehensive Cancer Center, Columbus. PATIENTS: Thirty-seven patients (median age, 63 years) with advanced oral cavity, oropharyngeal, or hypopharyngeal carcinomas. RESULTS: The range of time at risk was 1 to 30 months (median, 21 months). Thirty of the 37 registered patients were analyzable; 11 have died (5 with distant metastases; 1 of lung carcinoma; and 5 were cancer-free); 2 experienced second primary tumors in the oral cavity (out of or adjacent to the previous radiotherapy portals). Treatment compliance was excellent (92%), morbidity was low, and excellent locoregional control was achieved. CONCLUSIONS: The initial results are encouraging; the future strategy will intensify the systemic component of therapy based on results from concurrent laboratory studies.

Antineoplastic Agents↗
PubMed1997

Cell-to-cell and cell-to-matrix interactions mediate chemokine expression: an important component of the inflammatory lesion.

Although many studies have characterized soluble factors that stimulate or inhibit chemokine secretion, in this review we focus on the event of cellular adhesion as a novel mechanism for stimulating chemokine expression. Recent work has demonstrated chemokine expression following cell-to-cell and cell-to-matrix adhesion. The specificity of this finding was demonstrated utilizing various techniques that illustrate that adhesion, and not a soluble stimulus, is in some cases responsible for initiating or augmenting chemokine expression. For example, co-cultures of peripheral blood monocytes and endothelial cells secreted elevated levels of IL-8 and MCP-1 compared with either cell type alone. When co-cultured in transwells, this effect was significantly attenuated. In other experiments, neutralizing monoclonal antibodies to various adhesion molecules inhibited chemokine expression. The effects of adhesion were not limited to leukocytes. Both immune and non-immune cell types were evaluated as potential sources of adhesion-mediated chemokine expression. Not suprisingly, expression of some chemokines was associated with adhesion, whereas others were not, supporting the notion that adhesion differentially signals chemokine secretion during the inflammatory response. We hypothesize that as a recruited leukocyte encounters different adhesion substrates such as endothelial cells, basement membrane, extracellular matrix, and fibroblasts, the expression of chemokines from both the leukocyte and the substrate may be initiated, inhibited, or augmented. Careful characterization of the contribution of adhesion to regulation of chemokine expression will provide insight into the pathogenesis of many human diseases where chemokines have a central role.

Animals↗
PubMed1997

Transradial artery coronary angiography and intervention in patients with severe peripheral vascular disease.

BACKGROUND: Traditionally, cardiac catheterization in patients with severe aorto-iliac disease has been performed using a brachial arteriotomy. This approach is associated with significant vascular and neuronal complications and requires considerable training to achieve an adequate level of expertise. Improvement and miniaturization of catheter equipment now allows the radial artery to be used for coronary investigation and intervention. The lack of important structures close to the radial artery, a good collateral ulnar artery circulation and its superficial position suggests that these procedures should have a low complication rate. The purpose of this study was to assess the efficacy and safety of percutaneous transradial diagnostic and interventional coronary catheterization in patients with severe peripheral vascular disease. PATIENTS AND METHODS: We undertook a non-randomized prospective analysis of 75 patients who had transradial artery diagnostic and interventional coronary catheterization in whom femoral angiography was impossible or relatively contraindicated (22 patients with severe claudication and absent femoral pulses, 24 patients with previous aorto-iliac surgery or intervention, 20 patients with a failed femoral approach, 9 patients with an aortic aneurysm). Three patients had an absent ulnar artery and were excluded. RESULTS: Radial artery cannulation was successful in 73/75 (97%) cases. Seventy-one (95%) patients had a successful diagnostic study. There was a high incidence of 3 vessel disease (73%), and the majority of patients (64%) were referred for coronary bypass surgery. Twelve patients underwent successful follow-on intervention including the insertion of 9 intracoronary stents. Adequate haemostasis was achieved within 20 min after diagnostic angiography and 60 min after interventional procedures. One patient had a forearm haematoma with paraesthesia of the hand which settled with conservative treatment. At 4-6 weeks, all patients had normal hand sensation and function (100%) with a palpable pulse present in 59/62 (96%). All patients undergoing diagnostic angiography were discharged on the same day, and patients undergoing intervention were discharged the following day. CONCLUSIONS: Transradial coronary investigation and intervention can be performed with a high degree of success and a low complication rate with early mobilization and discharge in patients with severe peripheral vascular disease. We suggest that the percutaneous transradial technique should be considered as an alternative to the Sones' technique in these patients.

Angioplasty, Balloon, Coronary↗