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G L Smith

Publications and source records attributed to G L Smith.

At least 55 records · Page 3Linked to original sources
PubMed2000

Cellular basis for contractile dysfunction in the diaphragm from a rabbit infarct model of heart failure.

Abnormal respiratory muscle function is thought to contribute to breathlessness and exercise intolerance in heart failure but little is known about possible alterations in the function of such muscle. We have measured tetanic force and intracellular Ca(2+) concentration ([Ca(2+)](i)) in isolated, arterially perfused hemidiaphragm preparations from a rabbit coronary artery ligation model of heart failure. Increasing stimulation frequency (10-100 Hz) caused a progressive increase of force and [Ca(2+)](i) in control preparations, whereas force and [Ca(2+)](i) only increased between 10 and 25 Hz stimulation (decreasing at higher frequencies) in preparations from ligated animals. Cyclopiazonic acid produced a dose-dependent shift in the relationship between stimulation frequency and [Ca(2+)](i) in control preparations that was similar to the shift observed in the diaphragm of coronary-ligated animals. These data indicate that the in vitro contractile characteristics of the diaphragm are significantly altered in our model and that altered [Ca(2+)](i) regulation contributes to the reduced diaphragm strength observed in heart failure.

Animals↗
PubMed2000

P(i) inhibits the SR Ca(2+) pump and stimulates pump-mediated Ca(2+) leak in rabbit cardiac myocytes.

Measurements of sarcoplasmic reticulum (SR) Ca(2+) uptake were made from aliquots of dissociated permeabilized ventricular myocytes using fura 2. Equilibration with 10 mM oxalate ensured a reproducible exponential decline of [Ca(2+)] from 600 nM to a steady state of 100-200 nM after addition of Ca(2+). In the presence of 5 microM ruthenium red, which blocks the ryanodine receptor, the time course of the decline of [Ca(2+)] can be modeled by a Ca(2+)-dependent uptake process and a fixed Ca(2+) leak. Partial inhibition of the Ca(2+) pump with 1 microM cyclopiazonic acid or 50 nM thapsigargin reduced the time constant for Ca(2+) uptake but did not affect the SR Ca(2+) leak. Addition of 10 mM inorganic phosphate (P(i)) decreased the rate of Ca(2+) accumulation by the SR and increased the Ca(2+) leak rate. This effect was reversed on addition of 10 mM phosphocreatine. 10 mM P(i) had no effect on Ca(2+) leak from the SR after complete inhibition of the Ca(2+) pump. In conclusion, P(i) decreases the Ca(2+) uptake capacity of cardiac SR via a decrease in pump rate and an increase in Ca(2+) pump-dependent Ca(2+) leak.

Animals↗
PubMed2000

Prognostic significance of vascular endothelial growth factor protein levels in oral and oropharyngeal squamous cell carcinoma.

PURPOSE: Vascular Endothelial Growth Factor (VEGF) promotes angiogenesis in many different tumor types. VEGF levels may affect tumor growth, metastatic potential, and response to radiotherapy. This study assesses the prognostic value of VEGF protein levels in a cohort of patients with oral and oropharyngeal squamous cell carcinomas. The relationships between clinical outcome and the covariables of tumor-node-metastasis stage, disease stage (I to IV), grade, margin status, race, sex, and age were also determined. PATIENTS AND METHODS: Chart review identified 77 patients with oral or oropharyngeal squamous cell carcinoma treated with gross total surgical resection and postoperative radiation between 1981 and 1992. Sufficient follow-up data and tumor tissue were available in 56 patients (73%). VEGF protein levels were determined using immunohistochemistry. The association between VEGF status, covariables, and outcome was assessed in a bivariate and multivariate model using two-sided statistical tests. RESULTS: Twenty-three tumors (41%) were positive for VEGF expression. VEGF-positive tumors were more likely to recur locally (relative risk [RR] = 3.08; 95% confidence interval [CI], 1.03 to 9.24) and distantly (RR = 4.62; 95% CI, 1.41 to 15.10). In bivariate analysis, VEGF positivity was the most significant predictor of poor disease-free survival (RR = 2.66; 95% CI, 1.27 to 5.56) and overall survival (RR = 3.21; 95% CI, 1.63 to 6.32). In multivariate analysis, VEGF positivity was the most significant predictor of poor disease-free survival (RR = 2.75; 95% CI, 1.30 to 5.79) and overall survival (RR = 3.53; 95% CI, 1.75 to 7.13). CONCLUSION: In this cohort, VEGF positivity was the most significant predictor of poor prognosis. VEGF status may prove to be an important prognostic factor in head and neck cancer.

Adult↗
PubMed2000

Expression of a single pair of desmosomal glycoproteins renders the corneal epithelium unique amongst stratified epithelia.

PURPOSE: To determine desmosomal glycoprotein isoform expression in bovine corneal, limbal, and conjunctival epithelium and desmosomal profile and distribution during corneal re-epithelialization. METHODS: Immunofluorescence (IF) for desmosomal components on cryostat sections of fresh epithelia was supported by immunoblot analysis of tissue lysates. Wounded corneas maintained in organ culture were examined by IF at times up to full re-epithelialization (96 hours). RESULT: Immunofluorescence for desmoplakin confirmed desmosome presence throughout all three epithelia. Plakoglobin was also ubiquitous. Of the desmosomal glycoproteins, desmocollin 2 (Dsc2) and desmoglein 2 (Dsg2) were expressed throughout, but Dsc3 and Dsg3 were confined to the limbus and conjunctiva, and Dscl and Dsgl were absent. Dsc2 and Dsg2 IFs were stronger in superficial layers, but Dsc3 and Dsg3 were stronger basally, fading suprabasally. Glycoprotein expression in cornea and conjunctiva was confirmed by immunoblot analysis. No change in glycoprotein expression occurred during re-epithelialization. CONCLUSIONS: Uniquely among stratified epithelia, cornea expresses only a single pair of desmosomal glycoproteins, Dsc2 and Dsg2. Expression of Dsc3 and Dsg3 in limbus and conjunctiva coincides with their association with cell proliferation in other epithelia, but corneal epithelial cells did not express Dsc3 or Dsg3 during re-epithelialization. Absence of Dscl and Dsgl correlates with lack of keratinization in ocular epithelia. These expression patterns may have significance for the specific properties and differentiation patterns of the epithelia. Presence of desmosomes throughout re-epithelialization raises the question of how migrating cells mutually re-position.

Animals↗
PubMed1999

Inverse relation between prostate-specific antigen and insulin-like growth factor-binding protein 3 in bone metastases and serum of patients with prostate cancer.

The usual osteoblastic phenotype of metastatic prostate cancer is unexplained. Here we show that tissue and serum concentrations of prostate-specific antigen (PSA)-vary inversely with a substrate protein that binds a growth factor known to activate osteoblasts. These findings suggest that PSA may contribute to the osteoblastic phenotype, and could thus represent a new drug target devoid of antiandrogenic toxicity.

Biomarkers, Tumor↗
PubMed1999

The effects of targeting the vaccinia virus B5R protein to the endoplasmic reticulum on virus morphogenesis and dissemination.

The consequence of redirecting the vaccinia virus (VV) B5R protein to the endoplasmic reticulum (ER) has been investigated by the addition of an ER retrieval signal KKSL (K(2)X(2)) to the B5R C-terminus. This mutant B5R gene and a version of the gene with the inactive ER retrieval sequence KKSLAL (K(2)X(4)) were inserted into the thymidine kinase locus of a VV mutant lacking the B5R gene, vDeltaB5R. Similar levels of B5R protein were made by each virus, but the B5R-K(2)X(2) protein remained sensitive to endoglycosidase H and colocalised with protein disulphide isomerase in the ER. In contrast, the B5R-K(2)X(4) protein colocalised with 1, 4-galactosyltransferase in the trans-Golgi network. Electron microscopy revealed that even when the B5R protein was redirected to the ER, intracellular mature virus particles were wrapped by cellular membranes to form intracellular enveloped virus particles, although more incompletely wrapped particles were evident compared with wild type. These intracellular enveloped virus particles were, however, unable to efficiently induce the polymerisation of actin and the plaque size formed by vB5R-K(2)X(2) was small. Nevertheless, the amount and specific infectivity of EEV produced by vB5R-K(2)X(2) were similar to those of wild type, despite the dramatic reduction in the amount of B5R protein present in vB5R-K(2)X(2) EEV.

Actins↗
PubMed1999

Calcium/calmodulin-dependent protein kinase II activity is increased in sarcoplasmic reticulum from coronary artery ligated rabbit hearts.

A protein kinase activity intrinsic to the sarcoplasmic reticulum was studied in normal and hypertrophied rabbit hearts. The relationship between this kinase activity and phospholamban phosphorylation was examined. Calmodulin-dependent kinase II activity was found to be increased in sarcoplasmic reticulum preparations from hypertrophied hearts compared with normal. This was evident by measuring the phosphotransferase activity of the kinase and also by examining phospholamban phosphorylation by electrophoretic band shift analysis. Increased phospholamban phosphorylation by Calmodulin-dependent protein kinase II was dependent on prior phosphorylation by cAMP-dependent protein kinase, indicating potential crosstalk. Specific immunoblot analysis of the rabbit sarcoplasmic reticulum identified the presence of the delta form of calmodulin dependent protein kinase II and showed it to be up-regulated in hypertrophied hearts.

Animals↗
PubMed1999

Vaccines for smallpox.

Explore the source record for details and available documents.

AIDS-Related Opportunistic Infections↗
PubMed1999

Cell motility and cell morphology: how some viruses take control.

Viruses replicate inside host cells, where they use host biochemical and structural components to facilitate the production of new virus particles. As a consequence of co-evolution with their hosts, viruses have acquired host genes and genetic mutations that confer dominance over normal cell function. Research on virus-cell interactions has focused on the identification of mechanisms of virus dominance in order to develop therapeutic strategies for preventing productive infection. Although such research remains an essential part of molecular virology, viruses are also important genetic tools that can be used to analyse cell function. Because virus genomes contain genetic information, some of which was derived from host cells, it is possible that the analyses of virus-host interactions might lead to the identification of functionally dominant virus genes and novel eukaryotic counterparts. In this article, we have described how transforming and non-transforming viruses can control cell motility (cell migration or membrane projection), and explained how the analysis of virus cytopathic effects (CPEs) led to the identification of a novel family of cellular genes that regulate diverse aspects of cell motility.

Journal Article↗
PubMed1999

Effective induction of HIV-specific CTL by multi-epitope using gene gun in a combined vaccination regime.

Reliable and effective induction of cytotoxic T-lymphocytes (CTL) is one of the prime objectives of vaccine research. Previously, novel HIV vaccine candidates were constructed as a string of CTL epitopes (20 human, 3 macaque and 1 mouse) delivered using a DNA vector [Hanke T, Schneider J, Gilbert SG, Hill AVS, McMichael A. DNA multi-CTL epitope vaccines for HIV and Plasmodium falciparum: immunogenicity in mice. Vaccine 1998;16:426-435.] or modified vaccinia Ankara (MVA [Hanke T, Blanchard TJ, Schneider J, Ogg GS, Tan R, Becker MSC, Gilbert SG, Hill AVS, Smith GL, McMichael A. Immunogenicities of intravenous and intramuscular administrations of MVA-based multi-CTL epitope vaccine for HIV in mice. J Gen Virol 1998;79:83-90.]), i.e. vaccine vehicles acceptable for use in humans. In mice, a single intramuscular (i.m.) needle injection of either vaccine alone elicited good CTL responses. Here, it is demonstrated that the multi-epitope DNA also induced CTL when delivered intradermally using the Accell gene gun. The CTL responses increased after re-immunization and after three deliveries were comparable to those induced by a single i.m. injection. Recent evidence indicates that combining routes and vaccine vehicles enhances the immunogenicity of vaccine-delivered or -encoded antigens. Here, it is shown that administration of DNA by an i.m. priming/gene gun boosting more efficiently induced CTL than gene gun priming/i.m. boosting. A similar increment was obtained by sequential vaccinations using a gene gun-delivered DNA followed by recombinant MVA. Thus particular sequences of routes or vaccine vehicles rather than simple prime-boost delivery of a single vaccine is critical for an effective elicitation of CTL.

AIDS Vaccines↗
PubMed1999

Immune modulation by proteins secreted from cells infected by vaccinia virus.

Vaccinia virus comprises the live vaccine that was used for vaccination against smallpox. Following the eradication of smallpox, vaccinia virus was developed as an expression vector that is now used widely in biological research and vaccine development. In recent years vaccinia virus and other poxviruses have been found to express a collection of proteins that block parts of the host response to infection. Some of these proteins are secreted from the infected cell where they bind and neutralise host cytokines, chemokines and interferons (IFN). In this paper three such proteins that bind interleukin (IL)-1 beta, type I IFNs and CC chemokines are described. The study of these immunomodulatory molecules is enhancing our understanding of virus pathogenesis, yielding fundamental information about the immune system, and providing new molecules that have potential application for the treatment of immunological disorders or infectious diseases.

Animals↗
PubMed1999

Enhanced phosphorylation of phospholamban and downregulation of sarco/endoplasmic reticulum Ca2+ ATPase type 2 (SERCA 2) in cardiac sarcoplasmic reticulum from rabbits with heart failure.

OBJECTIVES: To assess the phosphorylation of myocardial phospholamban (PLB) and quantify protein levels of PLB and sarco/endoplasmic reticulum Ca2+ ATPase type 2 (SERCA 2) in a rabbit model of heart failure. Furthermore, to correlate these parameters with the rate of Ca2+ uptake into sarcoplasmic reticulum (SR) vesicles. METHODS: Heart failure in the rabbit was indicated by the pronounced ventricular contractile dysfunction accompanied by post-mortem evidence of lung and liver congestion 8 weeks after a coronary artery ligation procedure. Phosphorylation of PLB was measured by reduced mobility of the phosphorylated forms on Tris-glycine gels. Phosphoserine and phosphothreonine-specific antibodies against PLB were used to determine the phosphorylated residues. Immunoblotting combined with densitometry was used to assess PLB and SERCA 2 levels. Finally, oxalate-supported Ca2+ uptake into SR vesicles was studied using the fluorescent indicator Fura-2. RESULTS: The phosphorylation state of PLB was significantly higher in myocardium isolated from left ventricles of heart failure rabbits (8.3 +/- 0.42 P-PLB) when compared with sham-operated animals (4.0 +/- 1.7 P-PLB). The kinase activity associated with SR vesicles isolated from animals with heart failure was a factor of 1.58 +/- 0.21-times higher than sham hearts, as assessed by the initial rate of phosphorylation of PLB. This higher kinase activity observed in heart failure was not completely abolished by inhibitors of either A-kinase, C-kinase or Ca2+/calmodulin-dependent protein kinase (CaM-kinase). Abundance of SERCA in heart failure myocardial homogenates was significantly less than sham values (0.68 +/- 0.11 vs. 1.74 +/- 0.27) as was PLB (0.41 +/- 0.08 vs. 0.69 +/- 0.13), similar reductions were seen in vesicle preparations. The rate constant of Ca2+ uptake into the isolated SR vesicles was lower in preparations from heart failure myocardium than from sham myocardium (2.50 +/- 0.23 ms vs. 4.43 +/- 0.3 ms). CONCLUSIONS: The higher level of phosphorylation of PLB observed in the left ventricle of rabbits with heart failure is associated with a higher intrinsic kinase activity of the SR. However, the abundance of both of SERCA 2 and PLB proteins are lower in heart failure. The net effect of these changes appears to be a reduced rate of Ca2+ uptake by the SR in heart failure.

Animals↗
PubMed1999

Vaccinia virus immune evasion.

Vaccinia virus expresses many virulence factors that are non-essential for virus replication in cell culture but are important in vivo. In this paper three mechanisms are described that are used by vaccinia virus to evade the host immune response to infection. One of these is the release of a soluble protein that binds CC chemokines and that is unrelated to cellular chemokine receptors. The other two mechanisms are displayed by virus particles that are released from infected cells. This form of vaccinia virus is called extracellular enveloped virus (EEV) and is resistant to neutralisation by antibody and to destruction by complement. Resistance to complement is mediated by the acquisition of host complement control proteins, particularly CD55, during virus release from infected cells.

Animals↗
PubMed1999

An exploration of varieties of visual attention: ERP findings.

A set of five tasks was designed to examine dynamic aspects of visual attention: selective attention to color, selective attention to pattern, dividing and switching attention between color and pattern, and selective attention to pattern with changing target. These varieties of visual attention were examined using the same set of stimuli under different instruction sets; thus differences between tasks cannot be attributed to differences in the perceptual features of the stimuli. ERP data are presented for each of these tasks. A within-task analysis of different stimulus types varying in similarity to the attended target feature revealed that an early frontal selection positivity (FSP) was evident in selective attention tasks, regardless of whether color was the attended feature. The scalp distribution of a later posterior selection negativity (SN) was affected by whether the attended feature was color or pattern. The SN was largely unaffected by dividing attention across color and pattern. A large widespread positivity was evident in most conditions, consisting of at least three subcomponents which were differentially affected by the attention conditions. These findings are discussed in relation to prior research and the time course of visual attention processes in the brain.

Adolescent↗