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Biomedical subjects

H Tröster

Publications and source records attributed to H Tröster.

28 records · Page 2Linked to original sources
PubMed1991

[Impression management in behavior toward handicapped patients].

A previous study (Tröster, 1989) showed that nonhandicapped persons preferred a physically handicapped interaction partner to a nonhandicapped partner in an attributionally unambiguous situation. In order to test whether this "sympathy effect of physical handicap" is based on tendencies of impression management, 48 female subjects had to choose to sit next to either a physically handicapped or nonhandicapped female interaction partner in order to view a film together. Attributional ambiguity was varied by either confounding the choice of an interaction partner with a second, socially acceptable alternative (attributionally ambiguous situation: a choice between two films) or not confounding it (attributionally unambiguous situation: no choice between films). Public responsibility was manipulated by informing the subjects about their freedom to choose where they wished to sit either in public (public responsibility) or in private (no public responsibility). The results supported the impression management hypothesis: The handicapped interaction partner (in a wheelchair) was only preferred when the subjects had to anticipate that observers would deduce a preference of the chosen partner from the subjects' choices because of the attributionally unambiguous situation and the public announcement of their freedom of choice. Results suggest that the nonhandicapped strive to exhibit positive and nondiscriminative behavior toward the handicapped in order to avoid creating a disadvantageous impression in an observer.

Adult↗
PubMed1990

Structural organization of Acheta rDNA. Evidence for differential amplification of soma and germ-line-specific rDNA sequences.

Amplification is one of the mechanisms whereby the expression of genes can be specifically reinforced. Ribosomal gene amplification in amphibian and insect oocytes is a particularly well documented case. We studied heterogeneity, amplification and size of Acheta domesticus (insects; Orthoptera) ribosomal DNA and characteristics of male and female somatic or germ line rDNAs by analysis of genomic clones from a conventional and a microclone library. The length of the Acheta rDNA repeat unit (transcription unit and non-transcribed spacer (NTS] varied from 47 x 10(3) to 60 x 10(3) base-pairs, with highest variability within the NTS region. Deletions, fragment length heterogeneity and size variability in small steps of individual NTS segments are responsible for the observed size variation. The number of rDNA repeat units per haploid genome of Acheta was determined as 190(+/- 10%). The rDNA is amplified 14(+/- 10%)-fold in the oocyte, producing about 10,000 gene copies per cell. Our results show that the amplification mechanism does not favor individual fragments within the repeat unit. Thus, it can be concluded that amplification does not change the chromosomal characteristics of the rDNA pool. Two fragments specific for oocyte rDNA suggest that the rearrangements accompanying amplification are preferentially located in one distinct EcoRI fragment. Certain regions of Acheta rDNA contain cell-type-specific fragments: it was thus possible to characterize one purely male fragment and a second one specific for male and female soma but not for germ line rDNA. We show that Acheta rDNA reveals a combination of many features reported from different organisms and novel tissue-specific alterations on an extremely large repeat unit. The tissue-specific alterations indicate sexual and soma/germ line differentiation events that are derived by as yet unknown mechanisms.

Animals↗
PubMed1990

[Is self disclosure by a physically handicapped proband reciprocated by the interaction partner? An experimental study of the effect of physical handicap on interaction behavior with non-handicapped interaction partners].

An experimental study tested whether an able-bodied person's positive disposition toward a disabled interaction partner was effective in the amount of reciprocation given to the disabled partner's self-disclosure. Sixty female subjects were confronted with either a disabled or nondisabled conversation partner who showed either a high or a low amount of self-disclosure. We anticipated that a "sympathy" effect of disablement in the amount of the subjects' self-disclosure would result from the nondisabled partner's overcompensation. This arises from an effort to compensate the negative, stereotyped attitudes to the disabled in actual behavior toward a single, disabled person by more strongly reciprocating the self-disclosure of a disabled interaction partner compared to a nondisabled one. Results showed that, contrary to expectations, self-disclosure was equally reciprocated with both a disabled and a nondisabled partner. However, a "sympathy" effect was found in the impression judgments on the disabled partner who had shown a high amount of self-disclosure in the previous conversation. The lack of a "sympathy" effect in the amount of self-disclosure was possibly the result of (1) the reciprocation of self-disclosure not being exclusively determined by intentional control processes; and/or (2) the evaluative significance of the amount of self-disclosure not being clear to the subjects in the interaction studied. It is concluded that the efforts of the nondisabled to show an unprejudiced attitude toward a disabled interaction partner are mostly effective in other aspects of behavior than the amount of self-disclosure.

Adult↗
PubMed1989

Restriction analysis of lambda EMBL3 background recombinants: occurrence of lambda phages carrying a head to tail oriented left arm DNA sequence.

Eight representative recombinant background clones of lambda EMBL3 were analysed using KpnI, BamHI, SalI, EcoRI and HindIII digestion. We found that lambda EMBL3 carries its own left arm in the BamHI cloning site. In the way, recombinant molecules were found to be generated which can grow on Escherichia coli strain NM539. In all cases analysed, the left arm DNA was inserted in a head to tail orientation. Seven clones carried a restored BamHI site at the cos site-BamHI site connection. In the region where the inserted left arm and the right arm were ligated, BamHI cloning produces a large palindromic sequence consisting of two polylinkers. This BamHI site was incompletely cleaved in all cases analysed. We assume that a part of the lambda DNA molecule in this region shows a cruciform structure prohibiting recognition or cleavage of this site by restriction endonuclease BamHI.

Bacteriophage lambda↗
PubMed1985

Structural organization of an active, chromosomal nucleolar organizer region (NOR) identified by light microscopy, and subsequent TEM and STEM electron microscopy.

The three-dimensional arrangement of the chromatin components within the nucleolar organizer regions (NORs) from living oocyte nuclei was investigated. As a suitable cell system we chose vitellogenic oocytes of the orthopteran insect Acheta. This cell type is particularly attractive for analysis of nucleolar chromatin, since structural and functional aspects of NORs during early oogenic stages (including the association of NORs with amplified rDNA copies) are particularly well known (Lima-de-Faria 1974). In the course of the present study we first identified putative chromosomal NORs in isolated nuclei of mid-diplotene oocytes according to morphological characteristics using differential interference contrast (DIC) or phase contrast light microscopy. The presence of actively transcribing chromosomal NORs during this late stage of Acheta oogenesis obviously had been overlooked by previous investigators, probably due to difficulties of chromosome visualization. For a more detailed ultrastructural analysis, NORs were gently sedimented from opened nuclei and processed for sectioning using a modified "end-embedding" procedure (Mott and Callan 1975; Spring and Franke 1981). A small number of thick and thin sections could be made from individual NORs. Sections were analyzed by light microscopy, conventional transmission electron microscopy (TEM) and scanning transmission electron microscopy (STEM). Whereas the structural connection of NORs to the chromosome axis and also the general arrangement of active nucleolar genes within the NOR complex could be seen with TEM, the visualization of individual nucleolar genes and the organization of transcription complexes was only possible using bright field STEM of thick sections at low temperature.

Animals↗
PubMedDate not supplied

The age dependence of stereotyped behaviours in blind infants and preschoolers.

As part of a research programme on early intervention and family care for blind infants and preschoolers, the Bielefeld Parents' Questionnaire for Blind and Sighted Infants and Preschoolers was given to 85 parents of congenitally blind children. All 85 children (from 5 to 72 months) in the sample were totally blind and had no further serious disabilities. A comparison of five age groups of blind infants and preschoolers indicated that the repertoire of stereotyped behaviour patterns depended on age. After expanding from the first to the second year of life, the range of different stereotyped behaviours decreased from the age of 3 years up to school enrollment. The amount of stereotyped behaviours showed a similar course. Among the individual stereotyped behaviours, only the frequency of eye poking and body rocking increased from the first to the second year of life and then maintained a relatively high level across the entire preschool age range. The situational and person-specific conditions under which stereotyped behaviours could typically be observed also appeared to change with the child's age. While in the first years of life, monotony and arousal situations dominated among the elicited stereotyped behaviours, the 4- to 6-year-old blind children increasingly exhibited stereotyped behaviours in situations in which they were confronted with cognitive and concentrative demands. Various possible explanations of the age dependence of stereotyped behaviour patterns in blind infants and preschoolers are discussed.

Age Factors↗
PubMedDate not supplied

Early social-emotional development in blind infants.

In order to study the impact of blindness on social and emotional development during the first year of life, the level of social-emotional development was compared in blind and sighted 9- and 12-month-old infants. The five 9-month-old and the 17 12-month-old blind infants were completely blind from birth and exhibited no further serious disabilities. Social-emotional development was assessed with a scale from the Bielefeld Developmental Test for Blind Infants and Preschoolers containing three subscales on emotions, social interaction and impulse control. Compared to non-disabled infants, blind infants exhibited a more limited repertoire of facial expressions and less responsiveness. They less frequently attempted to initiate contact with their mothers (self-initiated interactions) or comply with simple requests and prohibitions than sighted infants. These differences in the social-emotional development of blind and sighted infants are traced back to the effects of blindness on the mother-child interaction. The lack of visual perception appears to impede particularly the acquisition of a dialogue concept.

Blindness↗