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Biomedical subjects

J Beck

Publications and source records attributed to J Beck.

At least 307 records · Page 17Linked to original sources
PubMed1966

Perceptual grouping produced by changes in orientation and shape.

The relative effectiveness of changes in orientation and shape in producing perceptual grouping has been stuidied using a method based on threshold judgments. Statistical analyses of the threshold vallues show that rotating some of the figures in afield from a vertical position to a slant of 45 degrees facilitates segregating the field into separate perceptual groups. In contrast, changes in the shape or orientation of these figures, which leave their component lines vertical and hlorizontal, do not reliably aid grouipinig. The results also suggest that the simli-larity of the figures comtposing the field is not a good predictor of the degree to which the figures will cohere to form distinct perceptual groups.

Adult↗
PubMedDate not supplied

Primary structure and evolutionary relationship between the adult alpha-globin genes and their 5'-flanking regions of Xenopus laevis and Xenopus tropicalis.

To investigate the evolution of globin genes in the genus Xenopus, we have determined the primary structure of the related adult alpha I- and alpha II-globin genes of X. laevis and of the adult alpha-globin gene of X. tropicalis, including their 5'-flanking regions. All three genes are comprised of three exons and two introns at homologous positions. The exons are highly conserved and code for 141 amino acids. By contrast, the corresponding introns vary in length and show considerable divergence. Comparison of 900 bp of the 5'-flanking region revealed that the X. tropicalis gene contains a conserved proximal 310-bp promoter sequence, comprised of the canonical TATA and CCAAT motifs at homologous positions, and five conserved elements in the same order and at similar positions as previously shown for the corresponding genes of X. laevis. We therefore conclude that these conserved upstream elements may represent regulatory sequences for cell-specific regulation of the adult Xenopus globin genes.

Animals↗
PubMedDate not supplied

Low grade malignant non-Hodgkin's lymphomas and peripheral pleomorphic T-cell lymphomas in childhood--a BFM study group report.

Non-Hodgkin's lymphomas (NHL) are classified as low or high grade malignant lymphomas of either B or T cell origin. Cells of low grade malignant NHL (LG-NHL) of B cell type represent either follicular or postfollicular, cells of LG-NHL of T cell type postthymic maturation stages in the lymphoid differentiation pathway. LG-NHL often fail to undergo long-term complete remission or cure in adults, no matter what type of conventional therapy is applied. In three pediatric therapy studies frequency and probability of continuous complete remission (pCCR) were studied for LG-NHL and peripheral pleomorphic T-cell lymphomas (PTCL). Of 432 evaluated patients only six children (1.4%) were qualified as LG-NHL. LG-NHL of T cell type were diagnosed in three children (one T-zone lymphoma, two PTCL of small cell type), LG-NHL of B cell type in another three cases. Two children presented with nodular type of centroblastic/centrocytic lymphoma (CB/CC), one with lymphoplasmocytoid type of immunocytoma (IC). In addition to the two patients with low grade malignant PTCL, there have been also four children with high grade malignant PTCL. The analysis showed that there was not significant difference for event free survival of children with LG-NHL and HG-NHL, respectively (pCCR: 0.63 and 0.82, p = 0.29). In contrast, when comparing high and low grade PTCL versus all other types of childhood NHL (non-PTCL), a significant difference seems to exist (pCCR for PTCL: 0.44, for non-PTCL: 0.83; p = 0.02). However, for further concisive conclusions more patients are needed for evaluation.

Adolescent↗