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Biomedical subjects

Robert Johnson

Publications and source records attributed to Robert Johnson.

At least 19 recordsLinked to original sources
PubMed2006

Dystocia in an injured common eastern long-necked turtle (Chelodina longicollis).

Dystocia in the class Reptilia is a common problem. In turtles, it is often difficult to distinguish between a normal gravid state and dystocia. This case report describes nonobstructive dystocia in a free-living freshwater chelonian, Chelodina longicollis, complicated by traumatic injuries to the head, bridge, and plastron. Medical treatment of the dystocia and external fixation of the facial injuries provided a successful outcome.

Accidents, Traffic↗
PubMed2006

Role of african-american fathers in child-rearing and oral health practices in an inner city environment--a brief communication.

OBJECTIVE: This study assesses parenting behaviors, health behaviors and attitudes in a sample of disadvantaged African-American fathers and evaluates the potential of fathers as recipients of oral health promotion interventions. METHODS: Participants were 60 African-American fathers whose children were enrolled in a childhood caries prevention study at Women and Infant Child Program (WIC) (n=25) or who were members of a Young Fathers' Program (n=35) at an urban health center. Demographic factors, oral health knowledge, dental self-efficacy, parenting behaviors, readiness to change, and health promotion behaviors were assessed. RESULTS: Participants averaged 30.8 years of age (sd=8.6); children averaged 2.1 years (sd=0. 9). Half of the fathers always have lived with their own children and 92% had regular physical contact with their children. Almost half of the sample reported 'fair/poor' oral health status, while less than 25% reported 'fair/poor' general health. Fathers had high oral health knowledge scores (x=7.7 correct of 9 items), and high readiness for change scores at the action stage (X=12.2 of 15; sd=1.9). dental self-efficacy scores were moderate (X=15.7 of 24; sd=5.5). Half of the fathers shared or had sole responsibility for brushing their children's teeth; 90% report children's teeth were brushed daily. CONCLUSIONS: African- American fathers participated in childrearing and oral health promotion behaviors.

Adult↗
PubMed2006

The effectiveness of dementia care mapping in intellectual disability residential services: a follow-up study.

This article is presented as a follow-up to exploratory work published in this journal in 2001. It describes a study that aimed to assess the effectiveness of dementia care mapping in supporting practice improvement in intellectual disability residential services. An average of 9 hours of observational data was collected using dementia care mapping in relation to 14 adults with severe or profound intellectual disabilities. Sixteen interviews were also undertaken with staff over a 4 month period.The findings provided a detailed picture of the activities and interactions between the participants involved in the study and raised some issues about 'organizational culture' when developing person-centred approaches. They have helped strengthen the case that care mapping has the potential to be a useful addition to the existing repertoire of tools to support effective practice improvement and person-centred planning.

Activities of Daily Living↗
PubMed2005

Cardiac magnetic resonance imaging after stage I Norwood operation for hypoplastic left heart syndrome.

BACKGROUND: After the Norwood operation, a patient's suitability for proceeding to a bidirectional cavopulmonary connection (BCPC) is assessed by a combination of echocardiography and diagnostic cardiac catheterization. In this study, we describe the results of 37 patients who underwent cardiovascular magnetic resonance (MR) assessment before BCPC. METHODS AND RESULTS: Cardiovascular MR and echocardiography were performed in 37 infants with hypoplastic left heart syndrome before BCPC, and the findings were compared with surgical findings. MR assessment of ventricular function and valvar regurgitation were compared with echocardiography. MR exhibited high sensitivity and specificity for identification of neoaortic (sensitivity 86%, specificity 97%) and left pulmonary artery (sensitivity 100%, specificity 94%) obstruction. Echocardiography exhibited poor sensitivity for identification of vascular stenosis. The mean right ventricular ejection fraction calculated from the MR data was 50+/-10%. There was general agreement between MR and echocardiographic measures of ventricular function, although patients with good function on echocardiography demonstrated a wide range of ejection fractions. There was good agreement between MR and echocardiography for identification of valvar regurgitation. CONCLUSIONS: Cardiovascular MR can be used to define ventricular and valvar function and vascular anatomy in infants with hypoplastic left heart syndrome after the Norwood operation. We have shown how this information can be used to plan the BCPC and identify any revisions or additional valvar surgery.

Aorta↗
PubMed2005

Preparation and characterization of nitrilotriacetic-acid-terminated self-assembled monolayers on gold surfaces for matrix-assisted laser desorption ionization-time of flight-mass spectrometry analysis of proteins and peptides.

On-target affinity capture, enrichment and purification of biomolecules improve detection of specific analytes from complex biological samples in matrix-assisted laser desorption ionization-time of flight-mass spectrometry (MALDI-TOF-MS) analysis. In this paper, we report a simple method for preparation of a self-assembled nitrilotriacetic acid (NTA) monolayer on gold surface which can be used as a MALDI-TOF-MS sample target specifically for recombinant oligohistidine-tagged proteins/peptides and phosphorylated peptides. The NTA functional groups are immobilized to the gold surface via the linkage of 1,8-octanedithiol which forms a self-assembled monolayer on gold. Characterization by X-ray photoelectron spectroscopy and MALDI analysis of the modified surface are described. The chemically modified surface shows strong affinity toward the analytes of interest, which allows effective removal of the common interferences, e.g. salts and detergents, and therefore leads to improved signal/noise ratio and detection limit. The use of the modified surface simplifies the sample preparation for MALDI analysis of these targeted analytes.

Gold↗
PubMed2005

Measurement of total pulmonary arterial compliance using invasive pressure monitoring and MR flow quantification during MR-guided cardiac catheterization.

Pulmonary hypertensive disease is assessed by quantification of pulmonary vascular resistance. Pulmonary total arterial compliance is also an indicator of pulmonary hypertensive disease. However, because of difficulties in measuring compliance, it is rarely used. We describe a method of measuring pulmonary arterial compliance utilizing magnetic resonance (MR) flow data and invasive pressure measurements. Seventeen patients with suspected pulmonary hypertension or congenital heart disease requiring preoperative assessment underwent MR-guided cardiac catheterization. Invasive manometry was used to measure pulmonary arterial pressure, and phase-contrast MR was used to measure flow at baseline and at 20 ppm nitric oxide (NO). Total arterial compliance was calculated using the pulse pressure method (parameter optimization of the 2-element windkessel model) and the ratio of stroke volume to pulse pressure. There was good agreement between the two estimates of compliance (r = 0.98, P < 0.001). However, there was a systematic bias between the ratio of stroke volume to pulse pressure and the pulse pressure method (bias = 61%, upper level of agreement = 84%, lower level of agreement = 38%). In response to 20 ppm NO, there was a statistically significant fall in resistance, systolic pressure, and pulse pressure. In seven patients, total arterial compliance increased >10% in response to 20 ppm NO. As a population, the increase did not reach statistical significance. There was an inverse relation between compliance and resistance (r = 0.89, P < 0.001) and between compliance and mean pulmonary arterial pressure (r = 0.72, P < 0.001). We have demonstrated the feasibility of quantifying total arterial compliance using an MR method.

Adolescent↗
PubMed2005

Chemical colloids versus biological colloids: a comparative study for the elucidation of the mechanism of protein fiber formation.

Fiber formation from murine serum amyloid A1 (SAA) was compared to the linear aggregation and fiber formation of colloidal gold particles. Here we report the similarities of these processes. Upon incubation with acetic acid, SAA misfolds and adopts a new conformation, which we termed saa. saa apparently is less soluble than SAA in aqueous solution; it aggregates and forms nucleation units and then fibers. The fibers appear as a string of the nucleation units. Additionally, an external electric field promotes saa fiber formation. These properties of saa are reminiscent of colloidal gold formation from gold ions and one-dimensional aggregation of the gold colloids. Colloidal gold particles were also found to be capable of aggregating one-dimensionally under an electric field or in the presence of polylysine. These gold fibers resembled in structure that of saa fibers. In summary, protein aggregation and formation of fibers appear to follow the generalized principles derived in colloidal science for the aggregation of atoms and molecules, including polymers such as polypeptides. The analysis of colloidal gold formation and of one-dimensional aggregation provides a simple model system for the elucidation of some aspects of protein fiber formation.

Animals↗
PubMed2004

P4 and P1' optimization of bicycloproline P2 bearing tetrapeptidyl alpha-ketoamides as HCV protease inhibitors.

With the aim of improving HCV protease inhibitors reported in our previous manuscripts, we synthesized and evaluated a series of 1a-based tetrapeptidyl alpha-ketoamides with additional P4 modification. The promising analog discovered through this SAR, 5a, was further derivatized at P1' or P1 position. As a result of these efforts, we found that replacement of the P4 valine as seen in 1a with cyclohexylglycine (Chg) resulted in the discovery of 5a, 5c, and 5e endowed with improved cellular activity in comparison to 1a.

Amides↗
PubMed2004

Protein kinase A phosphorylation characterized by tandem Fourier transform ion cyclotron resonance mass spectrometry.

A microelectrospray ionization tandem Fourier transform ion cyclotron resonance mass spectrometry (ESI FT-ICR MS(n)) approach for structural characterization of protein phosphorylation is described. Identification of proteolytic peptides is based solely upon mass measurement by high field (9.4 Tesla) FT-ICR MS. The location of the modification within any phosphopeptide is then established by FT-ICR MS(2) and MS(3) experiments. Structural information is maximized by use of electron capture dissociation (ECD) and/or infrared multiphoton dissociation (IRMPD). The analytical utility of the method is demonstrated by characterization of protein kinase A (PKA) phosphorylation. In a single FT-ICR MS experiment, 30 PKA tryptic peptides (including three phosphopeptides) were mass measured by internal calibration to within an absolute mean error of |0.7 ppm|. The location of each of the three sites of phosphorylation was then determined by MS(2) and MS(3) experiments, in which ECD and IRMPD provide complementary peptide sequence information. In two out of three cases, electron irradiation of a phosphopeptide [M + nH](n+) ion produced an abundant charge-reduced [M + nH]((n-1)+*) ion, but few sequence-specific c and z(*) fragment ions. Subsequent IRMPD (MS(3)) of the charge-reduced radical ion resulted in the detection of a large number of ECD-type ion products (c and z ions), but no b or y type ions. The utility of activated ion ECD for the characterization of tryptic phosphopeptides was then demonstrated.

Amino Acid Sequence↗
PubMed2004

Ethics training: a genuine dilemma for engineering educators.

This is an examination of three main strategies used by engineering educators to integrate ethics into the engineering curriculum. They are: (1) the standalone course, (2) the ethics imperative mandating ethics content for all engineering courses, and (3) outsourcing ethics instruction to an external expert. The expectations from each approach are discussed and their main limitations described. These limitations include the insular status of the stand-alone course, the diffuse and uneven integration with the ethics imperative, and the orphaned status of ethics using the outside expert. A fourth option is proposed--a special modular option. This strategy avoids the limitations of earlier approaches and harmonizes well with curricular objectives and professional values. While some help is provided by a professional ethicist, the headliner for the series of seminars is a high-profile engineer who shares an ethics dilemma encountered in professional practice. Students discuss the case and propose solutions. The goal is to make ethics applicable to real-life problems facing working engineers and to help change behaviors.

Engineering↗
PubMed2004

Review of an institutional experience of coronary arterial fistulas in childhood set in context of review of the literature.

Coronary artery fistulas are uncommon in children. We conducted a retrospective review of the case notes of 17 children who presented to our institution with the diagnosis of a coronary fistula since 1970. Their median age was 2.3 years. In five patients, there were associated congenital cardiac anomalies, with four having these as part of the spectrum of tetralogy of Fallot. Surgical correction was performed in nine patients, while in five closure was achieved using percutaneous embolization with coils. No complications or deaths were encountered related to the treatments chosen. In two patients, further procedures were needed to close residual fistulas. The median follow-up was 16 years, and on echocardiography, all fistulas appeared to be successfully closed, albeit that we lost three patients to follow up. We also conducted a review of 426 cases of coronary fistulas reported in children in the English literature. We have compared these findings with our institutional experience.

Age Distribution↗
PubMed2003

Bivalent biogenic amine reuptake inhibitors.

A series of aryltropane-based bivalent ligands was prepared and investigated for binding potency and for their ability to inhibit reuptake of human dopamine, serotonin and norepinephrine transporters. The bivalent ligand 4, comprised of linking an aryltropane by an octamethylene spacer showed high efficacy for the human dopamine transporter and had a discrimination ratio of 130.

Adrenergic Uptake Inhibitors↗