Gerstmann-Sträussler-Scheinker disease (GSS) is a prion-related encephalopathy pathologically characterized by massive deposition of prion protein (PrP) amyloid in the central nervous system. The major component of amyloid fibrils isolated from patients of the Indiana kindred of GSS (GSS-Ik) is an 11-kDa fragment of PrP spanning residues 58 to approximately 150. These patients carry a missense mutation of the PRNP gene, causing a Phe-->Ser substitution at codon 198. We investigated fibrillogenesis in vitro by using synthetic peptides homologous to consecutive segments of GSS-Ik amyloid protein (residues 57-64, 89-106, 106-126, and 127-147) as well as peptides from the PrP region with the GSS-Ik mutation (residues 191-205 and 181-205, both wild type and mutant). Peptide PrP-(106-126) formed straight fibrils similar to those extracted from GSS brains, whereas peptide PrP-(127-147) formed twisted fibrils resembling scrapie-associated fibrils isolated from subjects with transmissible spongiform encephalopathies. Congo red staining and x-ray fibril diffraction showed that both straight and twisted fibrils had tinctorial and conformational properties of native amyloid. Conversely, the other peptides did not form amyloid-like fibrils under similar conditions. These findings suggest that the sequence spanning residues 106-147 of PrP is central to amyloid fibril formation in GSS and related encephalopathies.

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The B-myb gene is highly homologous to the c-myb protooncogene in several domains and also shares some of the functions of c-myb in that it can act as a transcriptional activator. In addition, the expression of both the B-myb and c-myb genes correlates with proliferation of normal hematopoietic cells. We investigated more directly the role of B- myb in proliferation of hematopoietic cell lines using B-myb-specific antisense oligonucleotides. We showed that several anti-B-myb oligonucleotides, complementary to distinct regions of the gene, inhibit significantly and in a dose-dependent manner the proliferation of all myeloid or lymphoid cell lines tested. This block in proliferation was not accompanied by detectable differentiation of U937 or HL60 cells to macrophages or granulocytes either spontaneously or after exposure to chemical agents. These data suggest that the B-myb gene, like c-myb, is necessary for hematopoietic cell proliferation.

A 38-year-old amenorrhoeic woman suffering from a prolactin (PRL) secreting adenoma, which had suprasellar extension as shown by caroe agonist (lisuride). PRL levels were lowered and after 1 year of treatment CAT showed a marked reduction of the tumour size. After 2 years of treatment menstruation returned and CAT demonstrated a further reduction of the adenomatous tissue. This study supports the suggestion that dopamine agonists possess an anti-proliferative effect on tumoural lactotrophic cells of humans.