Search PubMed⌕ Search

Biomedical subjects

S Waugh

Publications and source records attributed to S Waugh.

13 recordsLinked to original sources
PubMed2001

Process characterization for metal-affinity chromatography of an Fc fusion protein: a design-of-experiments approach.

The utility of a design-of-experiments approach was investigated for process characterization of a metal-affinity chromatographic purification process for an Fc fusion protein. This approach gave a better understanding of some of the key process variables as well as robustness for this step in the purification process. Single-variable experiments were employed to screen some of the potentially important variables in this step. Ranges for these variables were set based on prior experience in clinical manufacturing with similar processes. Following these experiments, a fractional factorial study was employed to further investigate the most important variables and their interactions. Key operational variables that had an impact on step yield and eluate purity were identified. In addition, the study helped identify a worst-case scenario for the step purity and helped assure that the rest of the process would successfully purify the product. This paper demonstrates the utility of a design-of-experiments approach for the characterization and validation of process chromatography steps in downstream processing. In addition, this study emphasizes the utility of robustness studies early in process development and establishes a strategy for future robustness studies.

Animals↗
PubMed1998

2'-Fluoropyrimidine RNA-based aptamers to the 165-amino acid form of vascular endothelial growth factor (VEGF165). Inhibition of receptor binding and VEGF-induced vascular permeability through interactions requiring the exon 7-encoded domain.

Vascular endothelial growth factor (VEGF) has been implicated in the pathological induction of new blood vessel growth in a variety of proliferative disorders. Using the SELEX process (systematic evolution of ligands by exponential enrichment), we have isolated 2'-F-pyrimidine RNA oligonucleotide ligands (aptamers) to human VEGF165. Representative aptamers from three distinct sequence families were truncated to the minimal sequence capable of high affinity binding to VEGF (23-29 nucleotides) and were further modified by replacement of 2'-O-methyl for 2'-OH at all ribopurine positions where the substitution was tolerated. Equilibrium dissociation constants for the interaction of VEGF with the truncated, 2'-O-methyl-modified aptamers range between 49 and 130 pM. These aptamers bind equally well to murine VEGF164, do not bind to VEGF121 or the smaller isoform of placenta growth factor (PlGF129), and show reduced, but significant affinity for the VEGF165/PlGF129 heterodimer. Cysteine 137 in the exon 7-encoded domain of VEGF165 forms a photo-inducible cross-link to a single uridine residue in each of the three aptamers. The aptamers potently inhibit the binding of VEGF to the human VEGF receptors, KDR and Flt-1, expressed by transfected porcine aortic endothelial cells. Furthermore, one of the aptamers is able to significantly reduce intradermal VEGF-induced vascular permeability in vivo.

Amino Acid Sequence↗
PubMed1998

Economic outcomes associated with the use of risperidone in a naturalistic group practice setting.

The purpose of this cohort pilot study was to compare the resource utilization and economic outcomes associated with the use of risperidone versus haloperidol in a naturalistic setting. Patient charts from a large psychiatric group practice were reviewed, and hospital billing data were obtained. Patients meeting the inclusion criteria were placed into one of two cohorts depending on their medication history. Thirty patients treated with risperidone met the selection criteria, and a random quota sampling technique was used to allow for a matched control cohort of 30 patients treated with haloperidol. In the haloperidol and risperidone cohorts, 24 and 28 patients, respectively, were evaluated statistically. Mean utilization rates and costs per patient per month for each service were estimated by using regression analysis. Patients in the risperidone cohort had significantly fewer hospitalizations than did those in the haloperidol cohort (P = 0.004). Likewise, risperidone patients had significantly lower hospitalization costs than haloperidol patients (P = 0.005). Conversely, patients treated with risperidone visited the physician more frequently than did those treated with haloperidol (P = 0.0005). Estimated mean total monthly costs were $123.34 lower (95% confidence interval = $464, $217) per patient in the risperidone cohort than in the haloperidol cohort ($1,636.11 vs $1759.45; P = 0.4693). Significant reductions in hospital costs in the risperidone cohort offset higher medication and physician costs. Overall, total monthly costs were similar for the two cohorts.

Antipsychotic Agents↗
PubMed1997

In vitro selection of RNAs that bind to the human immunodeficiency virus type-1 gag polyprotein.

RNA ligands that bind to the human immunodeficiency virus type-1 (HIV-1) gag polyprotein with 10(-9) M affinity were isolated from a complex pool of RNAs using an in vitro selection method. The ligands bind to two different regions within gag, either to the matrix protein or to the nucleocapsid protein. Binding of a matrix ligand to gag did not interfere with the binding of a nucleocapsid ligand, and binding of a nucleocapsid ligand to gag did not interfere with the binding of a matrix ligand. However, binding of a nucleocapsid ligand to gag did interfere with binding of an RNA containing the HIV-1 RNA packaging element (psi), even though the sequence of the nucleocapsid ligand is not similar topsi. The minimal sequences required for the ligands to bind to matrix or nucleocapsid were determined. Minimal nucleocapsid ligands are predicted to form a stem-loop structure that has a self-complementary sequence at one end. Minimal matrix ligands are predicted to form a different stem-loop structure that has a CAARU loop sequence. The properties of these RNA ligands may provide tools for studying RNA interactions with matrix and nucleocapsid, and a novel method for inhibiting HIV replication.

Base Sequence↗
PubMed1995

Comprehensive chemical modification interference and nucleotide substitution analysis of an RNA pseudoknot inhibitor to HIV-1 reverse transcriptase.

We had previously used in vitro RNA selection techniques to describe a consensus RNA pseudoknot that binds and inhibits HIV-1 reverse transcriptase (HIV-RT). In this work we constructed variants of this consensus pseudoknot in order to evaluate the contributions of individual nucleotide identities and secondary structure to affinity for HIV-RT. We have also used chemical modification of ligand RNAs to corroborate the predicted structure of the pseudoknot, to discover which modifiable groups are protected from chemical attack when bound to HIV-RT, and to find which modifications interfere with binding to HIV-RT. A novel interference study is presented which involves selection of ligands from a pool created by mixed reagent oligonucleotide synthesis in order to rapidly determine allowed substitutions of 2'-OCH3 groups for the usual 2'-OH group in such RNA ligands.

Antiviral Agents↗
PubMed1993

Independent binding of interleukin-1 alpha and interleukin-1 beta to type I and type II interleukin-1 receptors.

Interleukin (IL)-1 refers to a group of three polypeptide hormones with a wide range of cellular targets. Two types of IL-1 receptor have been identified and characterized by cDNA cloning. Both human type I and type II IL-1 receptors contain extracellular domains of approximately 310 residues and a single membrane-spanning region. The type I receptor contains a cytoplasmic domain of 213 residues. The cytoplasmic region of the type II receptor is 29 residues in length. It has been found recently that a number of cells express both forms of receptor. By analogy with other cytokine receptor systems, the two IL-1 receptors might be expected to form a heterodimeric complex, the type II receptor being an alpha-chain-like structure, functioning only to bind ligand, and associating with the type I receptor (a beta-chain-like structure) which would transduce signals. In this report we show that this is not the case, but rather that IL-1, when complexed to type II receptor, cannot bind type I receptors, and vice versa. These data show that the complex patterns often observed for IL-1 binding to cells cannot be accounted for by the same type of mechanism that underlies the behavior of, for example, the IL-2 system.

Antibodies, Monoclonal↗
PubMed1992

Characterization of a multi-copy gene for a major stage-specific cysteine proteinase of Leishmania mexicana.

lmcpb, a gene from Leishmania mexicana that encodes a major cysteine proteinase in the parasite, has been cloned and sequenced. LmCPb is related more to cysteine proteinases from Trypanosoma brucei and Trypanosoma cruzi than to a previously characterized cysteine proteinase, LmCPa, of L. mexicana. It contains a long C-terminal extension characteristic of similar enzymes of T. brucei and T. cruzi. The gene is multi-copy and tandemly arranged. lmcpb RNA levels are developmentally regulated with steady state levels being high in amastigotes, low in metacyclic promastigotes and undetectable in multiplicative promastigotes. This variation correlates with and may account for the stage-specific expression of LmCPb enzyme activity.

Amino Acid Sequence↗
PubMed1992

Coping responses in depressed, socially maladjusted, and suicidal adolescents.

To study the relation between specific coping-response preferences and three dimensions of psychological disturbance in adolescents, 41 adolescents who had been admitted to an inpatient psychiatry program completed measures of depression, social maladjustment, suicidality, and coping responses to stressful life events. Analysis indicated that lower affective regulation was associated with increased depression, higher emotional discharge was associated with increased social maladjustment, and lower problem solving was associated with suicide attempts.

Adaptation, Psychological↗
PubMed1991

Experimental autoimmune encephalomyelitis is exacerbated by IL-1 alpha and suppressed by soluble IL-1 receptor.

To assess the role of IL-1 in the development of experimental autoimmune encephalomyelitis (EAE), the effects of in vivo treatment with IL-1 alpha or an IL-1 antagonist on the clinical course of EAE were evaluated. First, Lewis rats were immunized with guinea pig myelin in CFA and treated for 19 consecutive days with i.p. injections of recombinant human IL-1 alpha. Clinical signs of paralysis in the IL-1 alpha-treated groups were of longer duration and of greater severity compared to placebo injected controls. In addition, more weight loss was observed in the IL-1 alpha-treated groups compared to controls. This enhanced weight loss was not due to IL-1 alpha injections alone as CFA-treated rats injected with IL-1 alpha did not lose weight when compared to placebo injected, CFA-treated controls. Second, soluble mouse rIL-1R (sIL-1R), which binds both IL-1 alpha and IL-1 beta, was given as an IL-1 antagonist. Treatment of guinea pig myelin/CFA immunized rats with sIL-1R for 13 consecutive days significantly delayed the onset of EAE, reduced the severity of paralysis and weight loss, and shortened the duration of disease. Treatment with sIL-1R was most effective in reducing EAE if administered for 15 consecutive days immediately after immunization. Shortened 5-day treatment regimens spanning days 1 to 5, days 6 to 10, or days 11 to 15 after immunization were less effective in reducing EAE. These data suggest that IL-1 may initiate or promote inflammation within the central nervous system. In addition, specifically blocking the biological activity of IL-1 in vivo by soluble receptors may prove beneficial for the treatment of autoimmune or inflammatory diseases.

Animals↗
PubMed1990

Cytokine receptors and B cell functions. I. Recombinant soluble receptors specifically inhibit IL-1- and IL-4-induced B cell activities in vitro.

IL-1 and IL-4 are important mediators of B cell growth and differentiation. The cell-surface receptors for these cytokines have recently been cloned and recombinant soluble receptors have been produced that bind their respective ligand. The ability of soluble forms of the murine IL-1R (sIL-1R) and IL-4R (sIL-4R) to inhibit B cell functions in vitro was examined. Proliferation of B cells treated with anti-Ig plus IL-1 or IL-4 was inhibited by the appropriate soluble receptor. sIL-4R also inhibited IL-4-dependent B cell differentiation as measured by: induction of IgG1 and IgE secretion by LPS blasts, down-regulation of IgG3 secretion by LPS blasts, increased Ia expression, and increased Fc epsilon R (CD23) expression. The inhibitory effects of the soluble receptors were found to be highly specific in that sIL-4R had no effect on IL-1-induced B cell activity and sIL-1R had no effect on IL-4 activity, further demonstrating the existence of two independent pathways of B cell activation directed by IL-1 and IL-4.

Animals↗