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Biomedical subjects

R Owens

Publications and source records attributed to R Owens.

At least 19 recordsLinked to original sources
PubMed2006

First steps towards effective methods in exploiting high-throughput technologies for the determination of human protein structures of high biomedical value.

The EC 'Structural Proteomics In Europe' contract is aimed specifically at the atomic resolution structure determination of human protein targets closely linked to health, with a focus on cancer (kinesins, kinases, proteins from the ubiquitin pathway), neurological development and neurodegenerative diseases and immune recognition. Despite the challenging nature of the analysis of such targets, approximately 170 structures have been determined to date. Here, the impact of high-throughput technologies, such as parallel expression of multiple constructs, the use of standardized refolding protocols and optimized crystallization screens or the use of mass spectrometry to assist sample preparation, on the structural biology of mammalian protein targets is illustrated through selected examples.

Animals↗
PubMed2001

Cellular basis of potato spindle tuber viroid systemic movement.

Viroids are small, nontranslatable pathogenic RNAs that replicate autonomously and traffic systemically in their host plants. We have used in situ hybridization to analyze the trafficking pattern of Potato spindle tuber viroid (PSTVd) in tomato and Nicotiana benthamiana. When PSTVd was inoculated onto the stem of a plant, it replicated and trafficked to sink, but not source, leaves. PSTVd was absent from shoot apical meristems. In the flowers of infected plants, PSTVd was present in the sepals, but was absent in the petals, stamens, and ovary. The replicative form of PSTVd was detected in the phloem. Our data demonstrate that (i) PSTVd traffics long distance in the phloem and this trafficking is likely sustained by replication of the viroid in the phloem, and (ii) PSTVd trafficking is governed by plant developmental and cellular factors. The dependency of PSTVd and other viroids on cellular mechanisms for RNA trafficking makes them excellent tools to study such mechanisms.

In Situ Hybridization↗
PubMed1999

Registration of stereo and temporal images of the retina.

The registration of retinal images is required to facilitate the study of the optic nerve head and the retina. The method we propose combines the use of mutual information as the similarity measure and simulated annealing as the search technique. It is robust toward large transformations between the images and significant changes in light intensity. By using a pyramid sampling approach combined with simulated reannealing we find that registration can be achieved to predetermined precision, subject to choice of interpolation and the constraint of time. The algorithm was tested on 49 pairs of stereo images and 48 pairs of temporal images with success.

Algorithms↗
PubMed1999

Development of novel monoclonal antibodies for the analysis of functional sites in FGF-2.

Fibroblast growth factor 2 (FGF-2) can function as a potent mitogen, as well as a survival factor for a variety of mammalian cell types. The biological effects of FGF-2 are mediated by its interaction with two types of cellular binding sites: (1) high affinity tyrosine kinase receptors; and (2) low affinity heparan sulfate proteoglycans (HSPGs) on the cell surface. Although numerous FGF-2 antibodies have been used previously to analyze its biological actions, few studies have utilized antibodies to analyze domains within FGF-2 involved in its interactions with the two binding sites. In this report, we describe the generation and use of two monoclonal antibodies against human recombinant FGF-2 (254F1 and 256A12) that inhibit FGF-2 function. However, these antibodies appear to target preferentially different domains within the FGF-2 molecule, and therefore differentially influence the interactions of FGF-2 with its low and high affinity receptors. 254F1 is a more effective inhibitor of the high affinity, receptor tyrosine kinase binding site, whereas 256A12 appears to be a better inhibitor of the low affinity, HSPG interactions. We also demonstrate that the two antibodies are potent inhibitors of FGF-2 stimulated vascular cell proliferation, and as such have potential use in the treatment of vascular hyperproliferative diseases.

3T3 Cells↗
PubMed1998

Disproportionate fetal growth and fingerprint patterns.

Fingerprint whorl patterns are formed during fetal life. In a group of 180 term infants, those with more fingerprint whorls tended to have a small abdominal circumference (P = 0.09) and high ratio of head to abdominal circumference (P = 0.008). These associations were independent of the relation between the whorl counts of the mothers and their infants. We also found an independent correlation between the babies' whorl count and the combination of increasing subscapular (P = 0.03) and decreasing triceps (P = 0.02) skinfold thicknesses of the mothers. Whorl patterns are associated with adult hypertension; maternal nutritional status may influence their common origin during fetal development.

Adult↗
PubMed1998

Nurses' attitudes towards cost-effectiveness and quality of care.

OBJECTIVE: To describe nurses' attitudes toward cost-effectiveness in nursing practice and its perceived effects on quality of care, and to examine the influence of role, education, and experience on these attitudes. DESIGN: A comparative, descriptive design was used. SETTING: Two community hospitals in the midwest. SUBJECTS: Registered nurses and licensed practical nurses. MEASUREMENTS AND MAIN RESULTS: Blaney Hobson Nursing Attitude Scale was used to measure nurses' attitudes toward cost-effectiveness. Demographic information was obtained by asking open-ended questions. Scores ranged from 30 to 96, with a mean score of 65.57 (SD = 13.58). CONCLUSIONS: Nurses with greater than 10 years experience had more positive attitudes than nurses with 10 years or less experience. Nurses in administration/management positions had more positive attitudes than did staff nurses. No significant correlation was found between education level and attitudes toward cost-effectiveness. The major concern of participants was that quality of care would suffer due to cost containment efforts. The majority of participants agreed that education in cost containment and budgetary issues should begin in basic nursing school and should be included in employer orientation programs.

Attitude of Health Personnel↗
PubMed1997

Psychosocial outcome of children evaluated for short stature.

OBJECTIVE: To assess the psychosocial functioning of adults who were evaluated as children for short stature and were not treated with human growth hormone. DESIGN: Inception cohort study. SETTING: Hospital-based pediatric endocrinology clinic. PARTICIPANTS: From 1975 to 1980, medical record review indicated that 181 of the children referred to our clinic for concerns about short stature were non-growth hormone deficient. In 1992 and 1993, we were able to recruit 35 of these patients for a follow-up study. Eligible subjects were at least 18 years of age at the time of follow-up. MAIN OUTCOME MEASURES: Standardized self-report questionnaires assessed various domains of psychosocial adjustment. Also, a brief test of intellectual functioning was administered and subjects underwent a semistructured in-person interview to evaluate pragmatic functioning and experiences associated with short stature. RESULTS: Few significant differences between the study sample and standardization samples were found on measures of psychosocial and intellectual functioning. Within-group childhood height during the first evaluation appointment was not significantly associated with most adult measures of psychosocial adjustment. Shorter adult stature was significantly associated with lower educational achievement, lower self-esteem, and greater emotional distress. CONCLUSIONS: The absence of significant psychosocial distress or impairment in these subjects brings into question one basis for hormonal treatment for non-growth hormone deficient short stature; that short stature in childhood is likely to lead to psychological dysfunction in adulthood. The results, however, also suggest that shorter stature in adulthood may constitute a psychosocial stressor, increasing vulnerability across several domains.

Adaptation, Psychological↗
PubMed1997

The in vivo and in vitro characterisation of an engineered human antibody to E-selectin.

BACKGROUND: E-selectin is an endothelial cell specific adhesion molecule that is believed to play an important role in the early stages of leukocyte extravasation. OBJECTIVES: Here we describe the construction and evaluation of an engineered human monoclonal antibody that blocks E-selectin function. RESULTS: SPLAT-1 is an engineered human monoclonal antibody that has a very similar affinity for E-selectin as its murine parent antibody. In vitro SPLAT-1 blocks the binding of human leukocytes to E-selectin and does not mediate antibody-dependent cellular cytotoxicity (ADCC) or complement-mediated lysis of endothelial cells. In vivo, SPLAT-1 inhibits the recruitment of leukocytes to cytokine-inflamed human skin grafted on to SCID mice and has a long circulating half-life in primates. It does not appear to provoke an immune response in primates even on repeat administration. CONCLUSIONS: SPLAT-1 has the characteristics of a antibody suitable for human therapy studies.

Animals↗
PubMed1997

Cell-to-cell movement of potato spindle tuber viroid.

Viroids are non-translatable, autonomously replicating circular RNAs that infect only plants. An important component of the viroid infection process is cell-to-cell movement; however, there is virtually no information available about the pathways and mechanisms of this process. In this study, potato spindle tuber viroid (PSTVd) has been used as a model system to investigate the mechanism of viroid cell-to-cell transport. Infectious RNA transcripts were produced from PSTVd cDNA clones in vitro, labeled with the nucleotide-specific fluorescent dye TOTO-1 iodide, and used for micro-injection. When injected into symplasmically isolated guard cells of mature tomato and tobacco leaves, PSTVd remained in the injected cells; in contrast, PSTVd injected into symplasmically connected mesophyll cells moved rapidly from cell to cell. A 1400 nt RNA containing only vector sequences was unable to move out of the injected mesophyll cells, but when PSTVd was fused to this transcript, the fusion RNA moved from cell to cell. At the DNA level, PSTVd cDNA also appears able to mediate cell-to-cell movement of plasmid DNA. These data indicate that (i) PSTVd moves from cell to cell via plasmodesmata, and (ii) this movement may be mediated by a specific sequence or structural motif.

Biological Transport↗
PubMed1997

Cryptosporidium parvum oocysts recovered from water by the membrane filter dissolution method retain their infectivity.

Cryptosporidium parvum oocysts infectious to neonatal BALB/c mice were processed by the cellulose-acetate membrane (CAM) filter dissolution method to determine if the procedure that utilizes acetone incubation and alcohol centrifugations alters their viability (determined by in vitro excystation) or infectivity (determined by infectivity bioassay). In addition, most oocysts with altered viability by desiccation, heat inactivation, and snap freezing that were processed by the CAM filter dissolution method were nonrefractile, unstained oocyst ghosts. The remaining organisms, oocyst shells, were lightly stained with the acid-fast stain. Infectious oocysts retained their infectivity and nonviable oocysts (oocyst shells) retained their morphology when processed by the CAM dissolution method. Infectious oocysts, oocyst shells, and oocyst ghosts produced positive reactions of similar intensity in direct immunofluorescence antibody staining, utilizing the MERIFLUOR Cryptosporidium/Giardia test kit. Cryptosporidium oocysts recovered from finished drinking water by the CAM dissolution method can be subjected to testing for their viability and infectivity.

Acetone↗
PubMed1996

Diagnosis of subclinical cryptosporidiosis in captive snakes based on stomach lavage and cloacal sampling.

The applicability of stomach lavage and cloacal swab techniques for diagnosis of subclinical cryptosporidiosis were tested in eight captive snakes subclinically infected with Cryptosporidium serpentis. Two feeding regimes were employed. The snakes were first fed 7 days prior to stomach and cloaca sampling, and then 3 days prior to sampling, and the oocysts were detected by fluorescein labeled monoclonal antibody (mAb) and by acid-fast stained (AFS) direct wet smear (DWS). The overall sensitivity of AFS DWS was 95% for stomach samples and 57% for cloacal samples, with false-negativity of 5% and 43%, respectively. A significant relationship (P < 0.01) was found between stomach and cloacal samples when mAb were used for oocyst detection. Stomach sampling was diagnostically superior to cloacal sampling for identifying snake subclinical cryptosporidiosis. Based on gastric aspirates, cryptosporidial infection was diagnosed in all eight animals, and only in two or four snakes when cloacal swab material was processed by AFS or by mAb, respectively. Feeding snakes 3 days prior to sampling facilitated diagnosis based on stomach samples; however, it did not improve diagnosis when cloacal samples were used. The fraction of oocyst-positive stomach samples was significantly higher (P < 0.05) for snakes fed 3 days prior to gastric lavage when compared with the fraction of positive samples of snakes fed 7 days prior to lavage. If subclinical cryptosporidiosis is suspected in a non-eating snake patient, force-feeding and stomach lavage, 3 days after the meal, is recommended.

Animals↗
PubMed1996

Human constant regions influence the antibody binding characteristics of mouse-human chimeric IgG subclasses.

Although antibody affinity is primarily determined by immunoglobulin variable region structure human IgG antibodies of the four subclasses specific for the same antigen have been shown to differ in their affinity. To explore the influence of the immunoglobulin constant region on functional antibody affinity, a set of V region identical mouse-human chimeric IgG subclasses specific for TAG72 (tumour-associated glycoprotein) were studied. Biomolecular interaction analysis (BIA) was used to determine the binding kinetics of whole IgG subclasses and F(ab')2 fragments. Despite identical V regions, binding kinetics differed for the four subclasses. The apparent dissociation rate constants of the intact immunoglobulins ranked IgG4 < IgG3 < IgG2 < IgG1. In contrast, analysis of the binding characteriztics of the F(ab')2 fragments derived from IgG1, IgG2 and IgG4 revealed identical binding kinetics. The structure of the constant regions of the humanized IgG subclass antibodies clearly influenced functional antibody affinity, as has been described for the murine IgG subclasses. The exact mechanism for this phenomenon remains obscure but such differences should be taken into account when designing or choosing antibodies for therapeutic use.

Animals↗
PubMed1996

The inhibition of antigen-induced eosinophilia and bronchoconstriction by CDP840, a novel stereo-selective inhibitor of phosphodiesterase type 4.

1. The novel tri-aryl ethane CDP840, is a potent and selective inhibitor of cyclic AMP phosphodiesterase type 4 (PDE 4) extracted from tissues or recombinant PDE 4 isoforms expressed in yeast (IC50S: 4-45 nM). CDP840 is stereo-selective since its S enantiomer (CT 1731) is 10-50 times less active against all forms of PDE 4 tested while both enantiomers are inactive (IC50S: > 100 microM) against PDE types 1, 2, 3 and 5. 2. Oral administration of CDP840 caused a dose-dependent reduction of interleukin-5 (IL-5)-induced pleural eosinophilia in rats (ED50 = 0.03 mg kg-1). The eosinophils in pleural exudates from CDP840-treated animals contained higher levels of eosinophil peroxidase (EPO) than cells from control animals, suggesting a stabilizing effect on eosinophil degranulation. CDP840 was approximately equi-active with the steroid dexamethasone in this model and was 10-100 times more potent than the known PDE 4-selective inhibitors rolipram and RP73401. The activity of CDP840 was not influenced by adrenalectomy, beta-sympathomimetics or beta-sympatholytics. 3. Antigen-induced pulmonary eosinophilia in sensitized guinea-pigs was reduced dose-dependently by CDP840 (0.01-1 mg kg-1, i.p.) and intracellular EPO levels were significantly higher. CDP840 was more potent in these activities than CT1731 or rolipram and comparable in potency to RP73401. 4. Rolipram or CDP840 were less active than dexamethasone in preventing neutrophil accumulation, or exudate formation in carrageenan-induced pleurisy in rats and thus do not exhibit general anti-inflammatory activity. 5. In sensitized guinea-pigs, aerosols of the antigen ovalbumin caused a dose-dependent bronchoconstriction demonstrated by an increase in pulmonary inflation pressure. Administration of CDP840 (0.001-1.0 mg kg-1, i.p.), 1 h before antigen challenge, resulted in dose-dependent reduction in response to antigen. This activity was not due to bronchodilatation since higher doses of CDP840 (3 mg kg-1) did not significantly change the bronchoconstrictor response to histamine. Rolipram was approximately 10 times less active than CDP840 in preventing antigen-induced bronchoconstriction. 6. These results confirm the observations that selective PDE 4 inhibitors reduce antigen-induced bronchoconstriction and pulmonary eosinophilic inflammation. CDP840 is more potent than rolipram in inhibiting native or recombinant PDE 4. Unlike the recently described potent PDE 4 inhibitor RP73401, CDP840 is more active than rolipram in the rat IL-5 model following oral administration. The novel series of tri-aryl ethanes, of which CDP840 is the lead compound, could be the basis of an orally active prophylactic treatment for human asthma.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1995

Use of peptide combinatorial libraries in drug design: the identification of a potent serotonin reuptake inhibitor derived from a tripeptide cassette library.

BACKGROUND: Medicinal chemistry traditionally requires the identification of biologically active molecules by synthesizing and screening each purified substrate. Further progress in drug discovery then requires definition of the structure-activity relationship of the lead compound. More recently, combinatorial chemistry has emerged as a way to examine structure-activity relationships by screening a large mixture of compounds synthesized in a predictably random manner, without the labor-intensive costs of molecular isolation and purification. We set out to use this approach to examine the structural requirements for peptide binding to serotonin and dopamine transporters. RESULTS: We screened a tripeptide cassette library for serotonin and dopamine reuptake inhibition using cloned transporter assay systems. The method has afforded a number of tripeptide pharmacophores with inhibitory IC50 values ranging from 10 microM to < 1 microM in the dopamine and serotonin reuptake systems. The conformation of one of these tripeptides, N-acetyl-D-Trp-L-Phe-D-Lys-CONH2 (which inhibits serotonin uptake with an IC50 of 10 microM) was compared to that of the serotonin uptake inhibitor s-fluoxetine, and was shown to be more similar in conformation to fluoxetine than was an analogous tripeptide containing L-Lys (IC50 > 50 microM). CONCLUSIONS: We have identified five tripeptides with inhibitory IC50 values of < 10 microM in the serotonin reuptake system. One tripeptide was predicted to have pharmacophore features similar to that of fluoxetine, a selective and potent non-peptide serotonin reuptake inhibitor. Our results suggest that tripeptides derived from combinatorial libraries will help to define the important structural elements of pharmacophores.

Animals↗
PubMed1995

Apocrine chromhidrosis involving the areolae in a 15-year-old amateur figure skater.

Apocrine chromhidrosis is a rare disease frequently localized to the face or axillae, and rarely has been reported to occur around the breasts. We report a 15-year-old amateur figure skater who displayed localized chromhidrosis around her areolae. The most common precipitating event was exercise. She was treated topically with capsaicin cream 0.025% with a subsequent decrease in symptomatology.

Adolescent↗