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Biomedical subjects

B H Schneider

Publications and source records attributed to B H Schneider.

18 recordsLinked to original sources
PubMed2001

Child-parent attachment and children's peer relations: a quantitative review.

The central premise of attachment theory is that the security of the early child-parent bond is reflected in the child's interpersonal relationships across the life span. This meta-analysis was based on 63 studies that reported correlations between child-parent attachment and children's peer relations. The overall effect size (ES) for child-mother attachment was in the small-to-moderate range and was quite homogeneous. ESs were similar in studies that featured the Strange Situation and Q-sort methods. The effects were larger for peer relations in middle childhood and adolescence than for peer relations in early childhood. ESs were also higher for studies that focused on children's close friendships rather than on relations with other peers. Gender and cultural differences in ESs were minimal. The results for the few studies on father-child attachment were inconclusive.

Adolescent↗
PubMed2000

Highly sensitive optical chip immunoassays in human serum.

Over the past decade the ability of refractometric optical sensors to quantitatively measure a wide range of biomolecules has been demonstrated. These include proteins, nucleic acids, microorganisms, and in competitive formats small molecules such as drugs and pesticides. Furthermore, by using high refractive index nanoparticles to amplify the biomolecular binding signal, sensitivities approaching those of well established diagnostic assays have been achieved. However, to date it has not been possible to show rapid detection of analytes in complex bodily fluids such as serum, in a one-step procedure, due to the interference resulting from non-specific binding (NSB) to the sensor surface. We have carried out preliminary work on the control of interference due to NSB using an optical chip based on the Hartman interferometer. This interferometer configuration employs a reference sensing region that can be functionalized separately from the specific sensing region. Optical chips were stored dry after surface functionalization, and rehydrated in serum. The observed level of background drift in serum was reduced by an order of magnitude when an exposed reference was used, compared to a reference which was blind to the sample. An additional 70% reduction in signal drift in serum was achieved by controlling the surface chemistry of the optical chip using a biotin-poly(ethylene glycol) (PEG) blocking agent. This functionalization procedure was combined with a sandwich assay using gold nanoparticles to develop a one-step assay for human chorionic gonadotropin (hCG) in human serum with a detection limit of 0.1 ng/ml for a 35 min assay.

Chorionic Gonadotropin↗
PubMed2000

Optical chip immunoassay for hCG in human whole blood.

We report on the development of an integrated optic chip sensor for performing rapid and sensitive immunoassays with human whole blood using human chorionic gonadotropin (hCG) as the model system. The optical chip is based on the Hartman interferometer, which uses a single planar lightbeam to address multiple interferometers, each comprising a signal/reference pair of sensing regions. The binding of antigen to specific capture antibodies on the signal sensing region causes a change in the refractive index of the surface layer, which is detectable by its effect on the evanescent field of the guided lightbeam. The reference-sensing region is coated with an irrelevant antibody, which optically cancels a large fraction of the non-specific adsorption that occurs on the specific-sensing region when the sensor is tested with clinical specimens. This work extends previous experiments with buffer and human serum to measurements in undiluted whole human blood. Optical chips were stored dry after surface functionalization, and rehydrated with blood. Colloidal gold nanoparticles conjugated to a second anti-hCG monoclonal antibody were used to provide signal amplification, thereby enhancing assay sensitivity, in a one-step procedure with the gold conjugate added to the test sample immediately prior to measurement. Background signals due to non-specific binding (NSB) in blood were found to be higher than those previously reported with human serum. In addition, a high level of background signal was found with the gold conjugate, which had not been observed in experiments with either buffer or serum. Nevertheless, hCG could be detected at 0.5 ng/ml within 10 min of sample application. The sensor response was linear over the concentration range 0.5-5 ng/ml hCG, as compared with the clinically-relevant range 0.3-1.5 ng/ml. Detection at higher concentrations was affected by scattering from large amounts of bound gold nanoparticles. However, initial binding rate measurements could be used to maintain assay quantitation.

Chorionic Gonadotropin↗
PubMed1999

Effects of vascular or luminal administration and of simultaneous glucose availability on glutamine utilization by isolated rat small intestine.

This study examined whether the route of glutamine administration and the simultaneous availability of glucose affect intestinal glutamine metabolism. We measured net substrate exchange rates of glutamine and its nitrogenous products in the isolated vascularly and luminally perfused rat small intestine (a) as a function of glutamine provision from either the vascular or the luminal or simultaneously from both sides and (b) as a function of simultaneous availability of glucose from various routes. When glutamine was provided from the lumen, only 19-32% of absorbed glutamine appeared intact in the venous effluent, but the release of metabolic products was 170 +/- 5 nmol N min-1 g-1. This measure of intestinal glutamine metabolism was unchanged when glutamine was available only in the vascular perfusate (164 +/- 6 nmol N min-1 g-1). It increased, however, to 271 +/- 14 nmol N min-1 g-1 (P < 0.001) when glutamine was available simultaneously from both the luminal and the vascular perfusate. Glutamine consumption (-110 +/- 6 vs. -70 +/- 5 or -91 +/- 5 vs. -73 +/- 7 nmol min-1 g-1; P < 0.05 each) and the production of citrulline (11.4 +/- 0.7 vs. 10.0 +/- 0.8 or 9.8 +/- 0.5 vs. 7.8 +/- 0.4 nmol min-1 g-1; P < 0.05 each) or ammonia (124 +/- 7 vs. 88 +/- 4; P < 0.01 or 78 +/- 4 vs. 68 +/- 5 nmol min-1 g-1) decreased when glucose (vascular or luminal perfusate) became available in addition to glutamine. We conclude that glutamine is utilized by the small intestine very efficiently regardless of the route of administration being enteral or parenteral. The two routes can be used interchangeably to provide the intestinal mucosa with glutamine. Glucose and glutamine may partially substitute each other, most likely for the purpose as a metabolic fuel.

Ammonia↗
PubMed1999

A multimethod exploration of the friendships of children considered socially withdrawn by their school peers.

Friendships of children considered socially withdrawn by their school peers were investigated within a population of elementary school children. Reciprocal friends were identified by a friendship nomination procedure; social withdrawal was assessed by peer nominations. Trained graduate students rated videotapes of dyads of friends (n = 58 dyads, of which 29 contained at least one withdrawn child) for selected features of friendship quality. In addition, each friend within a dyad provided ratings of the quality of the relationship. The videotaped data showed the withdrawn children to be somewhat restricted in their verbal communication with their friends, and less competitive with their friends, than were friends in a comparison group. In dyads consisting of one withdrawn and one nonwithdrawn child, the withdrawn child perceived the relationship as characterized by greater closeness and helpfulness than did the nonwithdrawn friend. Despite some signs of inhibited behavior within the friendship context, withdrawn children seem to have access to close friendships of high quality.

Child↗
PubMed1998

Program integrity in primary and early secondary prevention: are implementation effects out of control?

We examined the extent to which program integrity (i.e., the degree to which programs were implemented as planned) was verified and promoted in evaluations of primary and early secondary prevention programs published between 1980 and 1994. Only 39 of 162 outcome studies featured specified procedures for the documentation of fidelity. Of these, only 13 considered variations in integrity in analyzing the effects of the program. Lowered adherence to protocol was often associated with poorer outcome. There was mixed evidence of dosage effects. The omission of integrity data, particularly measures of adherence, may compromise the internal validity of outcome studies in the prevention literature. We do not view procedures for integrity verification as inconsistent with the adaptation of interventions to the needs of receiving communities.

Adolescent↗
PubMed1998

Cross-cultural comparison as doorkeeper in research on the social and emotional adjustment of children and adolescents.

Cross-cultural comparison serves a crucial function as a final test of paradigms that emerge in intracultural studies of child and adolescent adjustment and maladjustment. Beliefs about child and adolescent adjustment are inextricably linked to cultural values regarding the place of the individual in society. Socialization practices and coping behaviors differ in adaptive significance according to the economic structure of a society and its value system. It is argued that the doorkeeper function of cross-cultural research is performed most effectively when a wide range of cultures are sampled, for which core beliefs are measured directly and not inferred from the general literature on each culture, and multiple sources of information are tapped.

Adolescent↗
PubMed1997

Relational aggression, gender, and peer acceptance: invariance across culture, stability over time, and concordance among informants.

It has been proposed that overt physical and verbal aggression are more prevalent among boys and that covert aggression in the context of interpersonal relationships is more typical of girls. The purpose of this study was to replicate and extend American research on this topic to Italy. Italian elementary school pupils (n = 314) and their teachers provided nominations for aggression and prosocial behavior on 2 occasions within a single school year. Both peer and teacher nominations were highly stable, though there was very poor concordance between them. Peer nominations for both overt and relational aggression were linked to peer rejection. Contrary to expectations, boys scored higher than girls in both overt and relational aggression. Nevertheless, on the basis of the gender composition of extreme groups, the authors conclude that the distinction between overt and relational aggression is as useful in facilitating research on aggressiveness among girls in Italy as it is in the United States.

Aggression↗
PubMed1997

Predicting children's friendship status from their dyadic interaction in structured situations of potential conflict.

Dyads of 8-year-old friends identified by sociometric friendship nominations were followed through the end of the school year to determine if they remained friends. These dyads as well as a control group of nonfriends were observed while participating in two structured tasks designed to stimulate real life social situations of potential conflict. When negotiating the sharing of an object, friends made more proposals than nonfriends, spent more time negotiating, and compromised more in making their counterproposals. Compared with dyads in which the friendship did not continue through the end of the school year, dyads of continuing friends exhibited greater sensitivity in their negotiations. During a fast-paced, competitive game, friends engaged in more competitive behavior and followed the rules more closely than did nonfriends. However, behavior in this game was unrelated to the continuation of friendship.

Child↗
PubMed1997

Hartman interferometer: versatile integrated optic sensor for label-free, real-time quantification of nucleic acids, proteins, and pathogens.

The Hartman interferometer, a proprietary integrated optic sensor, provides a basis for a broad range of biomedical diagnostics, including antibody-based and gene probe-based assays. As with other evanescent-wave optical sensors, the interferometer measures the refractive index change resulting from biomolecular binding on a waveguide surface. The exciting promise of evanescent-wave sensors lies, in general, in their potential to be used as label-free, real-time transducers that can operate in a true mix-and-read fashion and provide fast, quantitative results. One of the major issues facing their development, however, is creating a simple, low-cost configuration for multianalyte testing. The Hartman interferometer addresses this challenge by relying on linearly polarized light and a planar waveguide format, thereby avoiding the problems associated with circular polarization and channel waveguides. We report preliminary experiments that demonstrate the applicability of this sensor configuration to detection of a wide range of protein, nucleic acid, and pathogen analytes.

Animals↗
PubMed1991

Aggression and social withdrawal as viewed by children's peers: conceptual issues in assessment and implications for intervention.

Children's peer assessments of aggressive and withdrawn behavior are fundamentally related to developmental changes in their understanding of others. This article synthesizes research relevant to the thesis that peer assessments are dependent on children's ability both to recall the previous behavior of their peers and to predict their likely future behavior. Social schema theory, borrowed from adult social psychology, is highly relevant to such recall and prediction. Age differences, affective biases, and gender roles may color children's assessments of their peers' social behavior. Such influences should be taken into account when conceptualizing interventions aimed at enhancing children's peer status, and in measuring the success of these interventions.

Aggression↗
PubMed1990

A hydrophilic plasma polymerized film composite with potential application as an interface for biomaterials.

A hydrophilic polymer composite film (approx. 420 nm thick), with potential application as an interface for biomaterials has been prepared on nonorganic substrates, which include glass, silicon, and aluminum foil, using a glow discharge plasma polymerization technique. A thin film (110 nm thick) polymerized from hexane provided an adherent protective coating for the substrate material, and covalent bonding sites for the outer layer polymerized from N-vinyl-2-pyrrolidone. This outer layer provided the hydrophilic surface or interface. The two layers were copolymerized for a short period during transition between monomers to provide an intimate covalently bonded diffuse interphase. Preliminary in vitro and in vivo biocompatibility studies indicate that the hydrophilic film is non-cytotoxic, and does not increase the inflammatory response when compared with negative controls.

Animals↗
PubMed1990

Marital satisfaction during recovery from self-identified sexual addiction among bisexual men and their wives.

To learn the effect of the self-label of "sexual addict" on the marital adjustment of bisexual married men, we studied a specific subset who viewed their homosexual activities as addictive. Forty men and women, representing 22 marriages, were studied via telephone interviews and/or written surveys. All had committed to monogamy when they joined 12-step, self-help programs four months to six years previously. Current marriage ratings were good for 47%, average for 37%, and poor for 16% of couples. Ten couples (45%) believed their current sexual relationship was good, 27% rated it poor, and 27% were abstinent at the time of the study. Although a strong homosexual identity was associated with difficulties in marital satisfaction, viewing the same-sex activities as compulsive facilitated commitment to the marriage and to monogamy.

Adaptation, Psychological↗
PubMed1977

Enzyme induction in Streptomyces hydrogenas, VII. Short-term accumulation of guanosine polyphosphates.

Cells of Streptomyces hydrogenans (ATCC 19631) synthesize guanosine 3'(2')-diphosphate 5'-triphosphate (pppGpp) and guanosine 3'(2')-diphosphate 5'-diphosphate (ppGpp). 10 to 20 min after addition of steroids to the culture medium, the amount of pppGpp and ppGpp increases 2- to 3-fold. At the same time, the cellular amount of both ATP and GTP has been found to increase. While "shift down" experiments arrest growth of the cells temporarily, steroids do not impair cell division of Streptomyces hydrogenans. It is suggested that ppGpp and pppGpp mediate the regulatory shut off of nucleic acid synthesis or control their increased turnover triggered by the steroids.

Adenosine Triphosphate↗