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Biomedical subjects

R H Bradley

Publications and source records attributed to R H Bradley.

At least 19 recordsLinked to original sources
PubMed2006

Hydration-dehydration of adsorbed protein films studied by AFM and QCM-D.

The hydration-dehydration process of an adsorbed human serum albumin film has been studied using atomic force microscopy (AFM) and a quartz crystal microbalance (QCM). All measurements were performed with identically prepared protein films deposited on highly hydrophilic substrates. Both techniques are shown to be suitable for following in situ the kinetics of protein hydration, and for providing quantitative values of the adsorbed adlayer mass. The results obtained by the two methods have been compared and combined to study changes of physical properties of the films in terms of viscosity, shear, Young's modulus, density and film thickness. These properties were found to be reversible during hydration-dehydration cycles.

Adsorption↗
PubMed2005

Orientation and confinement of cells on chemically patterned polystyrene surfaces.

UV/ozone oxidation was combined with a photomasking technique to produce adjacent regions of different chemistry on polystyrene (PS) surfaces. The surface chemistry and topography were studied using AFM, XPS and contact angle measurements. The physicochemical patterns were visualised by the condensation of water vapour upon the surfaces and by the differential attachment of Chinese hamster ovarian (CHO) cells. The orientation of CHO cells on 55 and 125 microm wide oxidised PS strips were measured and found to be highly dependent on the width of the oxidised feature. CHO cells in relatively close proximity to a linear polar/non-polar border showed significant axial alignment along the border. CHO cells can also be confined to specific regions of the polymer surface. Cells attached to larger areas (75 microm x 75 microm) were found to have a smaller average cell size than cells attached to the smaller (56 microm x 56 microm) areas.

Animals↗
PubMed2005

The influence of electrostatic forces on protein adsorption.

In this paper we investigate the importance of electrostatic double layer forces on the adsorption of human serum albumin by UV-ozone modified polystyrene. Electrostatic forces were measured between oxidized polystyrene surfaces and gold-coated atomic force microscope (AFM) probes in phosphate buffered saline (PBS) solutions. The variation in surface potential with surface oxygen concentration was measured. The observed force characteristics were found to agree with the theory of electrical double layer interaction under the assumption of constant potential. Chemically patterned polystyrene surfaces with adjacent 5 microm x 5 microm polar and non-polar domains have been studied by AFM before and after human serum albumin adsorption. A topographically flat surface is observed before protein adsorption indicating that the patterning process does not physically modify the surface. Friction force imaging clearly reveals the oxidation pattern with the polar domains being characterised by a higher relative friction compared to the non-polar, untreated domains. Far-field force imaging was performed on the patterned surface using the interleave AFM mode to produce two-dimensional plots of the distribution of electrostatic double-layer forces formed when the patterned polystyrene surfaces is immersed in PBS. Imaging of protein layers adsorbed onto the chemically patterned surfaces indicates that the electrostatic double-layer force was a significant driving force in the interaction of protein with the surface.

Adsorption↗
PubMed2005

Improved cellular adhesion to acetone plasma modified polystyrene surfaces.

The plasma polymerization of acetone has been used to modify polystyrene substrates for the controlled growth of human fibroblast cells. The surface modified polystyrene was studied by X-ray photoelectron spectroscopy, water contact angle and atomic force microscopy. This showed the surface oxygen levels and wettability to increase rapidly with exposure to the acetone plasma. High-resolution XPS allowed the determination of the relative amounts of surface hydroxyl, carbonyl and carboxyl groups. This showed that there was little incorporation of carboxyl groups in the deposited films. AFM measurements revealed the films to be conformal with a surface roughness equivalent to that of the underlying polystyrene substrate with film growth rates of approximately 0.5 nm min(-1). High edge-definition patterns were produced with a simple masking procedure and allowed the confinement of cells to selected areas of the substrate. These chemically patterned surfaces allowed the study of cells confined to particular regions of the substrate as a function of incubation time.

Acetone↗
PubMed2004

UV-ozone modification of plasma-polymerised acetonitrile films for enhanced cell attachment.

Plasma polymerisation is of great interest for modifying the surface properties of biomedical devices in order to control, for example, protein adsorption and cell attachment. In this paper we present results for plasma-polymerised acetonitrile deposited onto silicon or polystyrene substrates. The chemistry of films deposited under a range of experimental conditions was studied by X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR). XPS provided evidence that the elemental composition of the films varied with rf power to flow rate parameter (W/F) with films produced at higher W/F being deficient in nitrogen. FTIR revealed that the plasma deposited film contained a wide range of nitrogen functional groups including amine, imine and nitrile. Oxidation of the films by exposure to radiation from a low pressure mercury vapour lamp in an air ambient increased the surface oxygen levels from 3 to 17at.% after 300 s exposure. XPS also revealed that the oxidation process proceeded via the formation of carbonyl groups at short exposure times (<60s) while longer treatment times (>60s) resulted in an increase in the concentration of carboxyl groups. To assess their potential to support cell growth, polystyrene culture dishes coated with plasma deposited films and UV-ozone oxidised films were seeded with 1BR.3.N human fibroblast cells and incubated for up to 72 h. Un-oxidised plasma-polymerised acetonitrile films were found to give comparable cell attachment densities as tissue culture polystyrene. The greatest cell attachment density was found with plasma polymer films which had been UV-ozone treated for the longest time (300 s). Enhanced attachment to this surface was attributed to the high level of carboxylic groups found on this substrate.

Acetonitriles↗
PubMed2004

Cellular attachment and spatial control of cells using micro-patterned ultra-violet/ozone treatment in serum enriched media.

Ultra-violet Ozone (UVO) modified polystyrene (PS) surfaces were analyzed by X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), contact angle (CA), optical microscopy (OM) and cell culture experiments. UV/Ozone treatment up to 900 s was used to increase the surface oxygen concentration of PS surfaces from 0% to approximately 35% (unwashed) and 0% to approximately 27% (washed). The observed differences in oxygen concentration, between washed and unwashed surfaces, have been previously attributed to the removal of low molecular weight debris produced in this treatment process. Surface roughness (Rq) is known to affect cellular attachment and proliferation. AFM studies of the UV/Ozone treated PS surfaces show the surface roughness is an order of magnitude less than that expected to cause an effect. UV/Ozone treatment of PS showed a marked change in CA which decreased to approximately 60 degrees after 900 s treatment. The increased attachment and proliferation of Chinese hamster ovarian (CHO) and mouse embryo 3T3-L1 (3T3) cells on the treated surfaces compared to untreated PS were found to correlate strongly with the increase in surface oxygen concentration. Surface chemical oxidation patterns on the PS were produced using a simple masking technique and a short UV/Ozone treatment time, typically 20-45 s. The chemical patterns on PS were visualized by water condensation and the spatially selective attachment of CHO and 3T3-L1 cells cultured with 10% (v/v) serum. This paper describes an easily reproducible, one step technique to produce a well-defined, chemically heterogeneous surface with a cellular resolution using UV/Ozone modification. By using a variety of cell types, that require different media conditions, we have been able to expand the potential applications of this procedure.

3T3 Cells↗
PubMed2001

A comprehensive substance abuse treatment program for women and their children: an initial evaluation.

This article examines a comprehensive, residential substance abuse treatment program for women and their children. A majority of the 72 participants studied were African American single mothers, for whom crack/cocaine was the drug of choice. The women and their children were assessed repeatedly during treatment, and at 3, 6, and 12 months postdischarge. Program impact was estimated by comparing the outcomes of three groups that differed in the amount of treatment they received: early dropouts, late dropouts, and treatment graduates. Program graduates showed more positive outcomes than the nongraduate comparison groups in the areas of drug use and negative consequences of use, employment and self-sufficiency, and family interaction skills. Young children enrolled in treatment with their mothers were assessed using a developmental screening test, and older children with a measure of drug refusal skills. Results from both child measures suggest substantial improvement.

Adolescent↗
PubMed2000

Moderating effect of perceived amount of family conflict on the relation between home environmental processes and the well-being of adolescents.

This study examined the extent that perceived amount of conflict in the family moderates the relation between proximal aspects of the home environment and adolescent well-being. Regression models consisting of Home Observation for Measurement of the Environment (HOME) subscale scores (Responsivity, Learning Materials, Variety of Experiences), family conflict, and the interaction between HOME scores and family conflict were tested for each of 6 dependent measures: academic achievement, task orientation, being considerate, self-efficacy as it pertains to school, self-efficacy as it pertains to family, and school grades. Results indicated moderation in all 3 ethnic groups examined (European Americans, African Americans, and Chinese Americans). For all 3 groups, relations were stronger in families with high conflict, suggesting a heightened sensitivity to social exchanges and events within the family.

Adolescent↗
PubMed1996

Effects of poverty on home environment: an analysis of three-year outcome data for low birth weight premature infants.

Investigated the relationship between poverty and parenting in a sample of low birth weight (< or = 2,500 grams) premature (LBWPT) infants (gestation < or = 37 weeks) who were control subjects in the Infant Health and Development Program. When classified using federal poverty levels, poor families scored lower on the HOME inventory (used to measure the caregiving environment) than nonpoor families. A regression model including poverty, race, site, and representative environmental, maternal, and child variables accounted for 60% of variance in total HOME scores. Poverty and maternal IQ had significant and independent effects on HOME scores, whereas maternal distress accounted for little of the variance. In a LBWPT sample, our results find a strong relationship between parenting and poverty, suggest a modest role for maternal psychological distress in this relationship, and indicate that the influence of poverty likely extends beyond commonly measured environmental, maternal, and child factors.

Child, Preschool↗
PubMed1995

Home environment and adaptive social behavior among premature, low birth weight children: alternative models of environmental action.

Used data from 465 premature, low birth weight children representing three major sociocultural groups (Caucasian, African American, Hispanic) to examine the relation between children's home environments and their adaptive social behavior. Results showed low to moderate associations between scores on the HOME Inventory at 1 and 3 years and scores on two measures of adaptive social behavior at 30 to 36 months, the Adaptive Social Behavior Inventory, and observations of mother-child interaction in a structured laboratory situation. Results indicated that responsive, nurturant care at both 1 and 3 years are related to child adaptive social behavior, as are cognitively stimulating experiences and materials. However, canonical correlational analysis indicated that only Acceptance and Variety of Experience, measured at age 3, and Variety of Experience measured at age 1 accounted for independent amounts of variance in adaptive social behavior as perceived by mothers. Also, only sociocultural group status and Learning Materials at 36 months contributed to the prediction of persistence and enthusiasm as observed in the laboratory setting.

Adult↗
PubMed1995

Families of young technology-dependent children and the social worker.

Health care social workers are increasingly providing services to young children who are technology-dependent through participation on individualized family service plan (IFSP) teams, as well as in clinical settings. Such participation suggests that new models for assessing the impact of medical technologies on family functioning will, of necessity, also begin to emerge. Assessment implications from a family systems perspective are presented that may be used to guide the development of future assessment strategies for health care social workers.

Caregivers↗
PubMed1995

The amobarbital sodium interview in conversion disorders: use of video feedback in therapy.

The prognosis in treating acute conversion disorder is good, but it demands considerable time in the form of an intensive, and often extensive, hospital stay. With the increasing trend to limiting hospital stays, the family practitioner working with a psychiatrist in the hospital setting is pressured to find new approaches in order to limit the use of inpatient units. The authors describe a case of classic conversion disorder and outline a successful approach that uses a video recording of the interview, during which the patient is under the influence of amobarbital sodium. The videotape then provides valuable feedback during future therapy sessions in the treatment of this persistent disorder.

Adult↗
PubMed1994

A multifaceted intervention for infants with failure to thrive. A prospective study.

OBJECTIVE: To determine whether a multifaceted intervention decreased the incidence of failure to thrive (FTT) in a group of preterm infants with low birth weights and improved the 3-year intelligence, health, growth, and behavior status of the children with FTT. DESIGN: Three-year, prospective, randomized, clinical trial. SETTING: Eight large university hospital sites throughout the United States. SAMPLE: Nine hundred fourteen preterm infants with low birth weights who were born at the sites and met study criteria. INTERVENTION: Home visits weekly during the first year of life and biweekly thereafter until the age of 3 years to provide family support and implement two curricula; and attendance at a child development center from 12 months until 3 years of age, 5 days a week, to deliver an early childhood educational intervention. RESULTS: The incidence of FTT did not differ between the treatment and control groups (20% vs 22%). Overall, children with FTT in the treatment group were not different from children with FTT in the follow-up group on any of the outcome variables. However, after controlling for other factors, treatment group membership significantly contributed to the prediction model of 36-month IQ (P = .005) for the children with FTT. In addition, children with FTT in the intervention group with higher compliance demonstrated higher 3-year IQ and better behavior scores than the children with FTT in the low-compliance group. CONCLUSIONS: The intervention did not change the incidence of FTT or the 3-year outcomes in this low-birth-weight, preterm cohort. After controlling for multiple independent variables, marked effects on 3-year IQ were noted. In addition, these beneficial effects were most pronounced in families that were most complaint with the intervention.

Child Behavior↗
PubMed1994

A factor analytic study of the infant-toddler and early childhood versions of the HOME Inventory administered to white, black, and Hispanic american parents of children born preterm.

Factor analyses were performed on the Infant-Toddler and the Early Childhood versions of the HOME Inventory for 3 groups (blacks, whites, and Hispanics) of premature, low-birthweight children. Participants lived in 8 different U.S. cities. On the IT-HOME, 5 factors were originally retained for each group using the principal factors method of extraction. Factor structures for blacks and whites were similar, accounting for 85% and 75% of the variance, respectively. The structure for Hispanics was somewhat different; a 7-factor solution accounting for 65% of the variance was most interpretable. For the EC-HOME, 6 factors were retained for both black and white groups, accounting for 80% and 73% of the variance, respectively. For Hispanics, an 8-factor solution accounted for 59% of the variance. The factor structures for blacks and whites were largely in agreement with the current organization of items into subscales. The fit for Hispanics was not quite as good, but most factors also corresponded to current subscales.

Adult↗
PubMed1994

Early indications of resilience and their relation to experiences in the home environments of low birthweight, premature children living in poverty.

The caregiving environment experienced by 243 premature, low birthweight (LBW) children living in poverty was examined to determine whether the quality of care such children receive affords them some measure of protection from the generally deleterious consequences of poverty and prematurity. Only 26 children were identified as functioning in the normal range for cognitive, social/adaptive, health, and growth parameters at age 3. These children, who showed early signs of resiliency, differed from nonresilient children in that they were receiving more responsive, accepting, stimulating, and organized care. They were also living in safer, less crowded homes. 6 "protective" aspects of caregiving were identified and used as part of a cumulative protection index. Children with less than 3 protective aspects of caregiving present at age 1 had only a 2% probability of being resilient, and only a 6% probability if fewer than 3 were present at age 3. Overall, premature LBW children born into conditions of poverty have a very poor prognosis of functioning within normal ranges across all the dimensions of health and development assessed. However, those raised in a setting with 3 or more protective factors were more likely to show early signs of resiliency.

Adaptation, Psychological↗