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Biomedical subjects

D Friedrich

Publications and source records attributed to D Friedrich.

At least 19 recordsLinked to original sources
PubMed1989

[Is the visual fixation mark adequate visual attraction for babies in the 1st year of life?].

One of the most important clinical examinations in strabology is the test for foveal fixation. This test presupposes a mature primary visual pathway with well established afferent and efferent reactions, which certainly does not exist from birth. The presumed retinal fixation of 234 infants was critically examined during continuous observation in their first year of life.

Attention↗
PubMed1985

The core proteins of 35S hnRNP complexes. Characterization of nine different species.

Ribonucleoprotein complexes (hnRNP) containing fragments of heterogeneous nuclear (hn)RNA and sedimenting at 35-40 S were isolated from the nuclei of HeLa S3 cells using the pH 8.0/diffusion technique. These hnRNP complexes are thought to be part of the hnRNA processing apparatus. The major protein components (core proteins) were identified by their constant ratios in native particles and in 35S hnRNP particles reconstituted in vitro. All of the core proteins, with one exception, show an increase in Mr on sodium dodecylsulfate (NaDodSO4)/polyacrylamide gels containing 8 M urea, indicative of secondary structure elements resistant to denaturation by NaDodSO4. The nine core proteins found by us are: A1 [Mr(NaDodSO4) 31 X 10(3)/Mr (urea) 38 X 10(3), apparent isoelectric point, pIapp 9.3], A2 (32.5 X 10(3)/39 X 10(3), 8.4), B1a (35.5 X 10(3)/41 X 10(3), 8.8), B1b (35.5 X 10(3)/44 X 10(3), 8.3), B1c (35.5 X 10(3)/43 X 10(3), 5.7) B2 (37 X 10(3)/42 X 10(3), 9.15), C1 (39 X 10(3)/46 X 10(3), 9.2), C2 (40.5 X 10(3)/45 X 10(3), 5.55) and C3 (38.5 X 10(3)/37 X 10(3), 4.8). Individual proteins were electroeluted from two-dimensional gels and their amino acid composition determined. Difference indices were calculated and show a group of closely related basic proteins (A1, A2, B1a, B1b, B2, C1), two related slightly acidic proteins (B1c, C2) and a distinct acidic member (C3). Two-dimensional analysis of tryptic fragments and one-dimensional separation of peptides after V8 protease treatment support these data. Peptide mapping of the proteins A1 and A2 from bovine and human cells yields identical fragments indicating a high degree of cross-species conservation. An additional protein (D4: 44 X 10(3)/55 X 10(3), greater than 9.5) was found, which preferentially associates with heavier, oligomeric hnRNP structures. Only traces of actin are present in the 35S hnRNP fraction. All core proteins are modified by charge. A large part of the charge isomers arises by phosphorylation, which has been shown by labeling with 32PO4 in vivo and with [gamma-32P]ATP in vitro. In vitro the phosphate transfer is mediated by an endogenous protein kinase associated with the 35S hnRNP complexes. The major core protein A1 exists in two conformeric forms (A1 and A1x) of which only A1x serves as phosphate acceptor in vivo.

Amino Acids↗
PubMed1979

Visual-motor test performance: race and achievement variables.

Tested rural Michigan black (N = 60) and white (N = 60) children of variant academic achievement on the Minnesota Percepto-Diagnostic Test for visual-motor skill development. The test, which consists of six gestalt designs for the person to copy, includes four measures of such skill development: Degree of copied design rotation and errors of separation of circle-diamond, distortion of circle-diamond and distortion of dots. In general, analyses that statistically controlled for intellectual level indicated that race was not a significant variable in the relationship of achievement level and visual-motor test performance. That is, such analyses resulted only in a significant achievement effect; low achievers, in comparison with high achievers, performed poorly on the copying test. Only with distortion of circle-diamond errors was a race interactive effect noted; i.e., black low achievers had significantly more errors than black high achievers, white low achievers or white high achievers. Results were discussed in relation to environmental determinants and symptomatology correlates.

Achievement↗
PubMed1977

Read-out times from iconic memory in normal and retarded adolescents.

The method limits was used to obtain an estimate of read-out times for a sample of 12 normal and 12 retarded subjects matched on chronological age. The procedure required tachistoscopic presentation of a stimulus array (2, 4, or 6 digits) for a variable duration, followed by a post-stimulus. The subject's task was to recall the digit indicated by the cue. The results indicated that read-out time (a) increased as the number of digits increased, (b) was longer for retardates relative to normals, and (c) decreased with practice for both intelligence groups. The implications of a read-out deficit in retarded individuals were discussed.

Adolescent↗
PubMed1976

Differential diagnosis of psychiatric patients with the Minnesota Percepto-Diagnostic Test.

This study investigated whether normals, personality disorders, psychotics and organics could be differentiated by the Minnesota Percepto-Diagnostic Test. There were significant differences between all the groups except the psychotics and personality disorders. It appears that, in general, perceptual disturbance lies along a pathological continuum. Similar performances of psychotics and personality disorders were discussed.

Diagnosis, Differential↗
PubMed1975

Response-stimulus interval performance of moderately retarded institutionalized subjects.

Based on previous dual reaction-time research with nonretarded and mildly retarded subjects, the expectancy- and capacity-limit hypotheses for the psychological refractory period effect were tested with moderately retarded subjects. The design included regular-irregular procedure, response-stimulus interval, signal, and hand-preference variable levels. The finding of a psychological refractory period effect at the 250-msec response-stimulus interval was consistent with past related research. The moderately retarded subjects indicated a capacity limitation, resulting in the psychological refractory period effect at the rapid response-stimulus interval. Previous researchers working with nonretarded and mildly retarded subjects have suggested an expectancy explanation for the psychological refractory period. This inconsistency in study findings was interpreted on the basis of an organismic confound. Methodological issues were also presented.

Acoustic Stimulation↗