Oculocerebral syndrome with hypopigmentation (Cross syndrome): the mixed pattern of hair pigmentation as an important diagnostic sign.

The present report describes two female siblings of mixed ancestry (Cape Coloured) with consanguineous parents as further examples of Cross oculocerebral hypopigmentation syndrome. The mixed pattern of hair pigmentation as an important diagnostic sign is emphasized.     

Involvement of cyclic GMP in the fusion of chick embryonic myoblasts in culture.

We found that a transient rise in cGMP levels, which was closely associated with the Ca2+ influx, occurred concomitant with the onset of myoblast fusion. The Ca2+ channel blocker D600 decreased both the cell fusion and the normal rise in cGMP levels. In contrast, the Ca2+ ionophore A23187 transiently increased cGMP levels and induced precocious fusion. In addition, the cGMP analog 8-Br-cGMP induced precocious fusion as A23187 did. The guanylate cyclase inhibitor, methylene blue delayed the fusion in a dose-dependent manner without significantly affecting cell alignment, proliferation, or muscle-specific protein expression. Furthermore, methylene blue delayed the normal rise in cGMP levels, and the fusion block imposed by methylene blue was significantly recovered by 8-Br-cGMP. On the basis of our present findings, we suggest that a Ca2+ influx-dependent rise in cGMP levels is an important step in myoblast fusion.     

Evidence for a new extracellular peroxidase. Manganese-inhibited peroxidase from the white-rot fungus Bjerkandera sp. BOS 55.

A novel enzyme activity was detected in the extracellular fluid of Bjerkandera sp. BOS 55. The purified enzyme could oxidize several compounds, such as Phenol red, 2,6-dimethoxyphenol (DMP), Poly R-478, ABTS and guaiacol, with H2O2 as an electron acceptor. In contrast, veratryl alcohol was not a substrate. This enzyme also had the capacity to oxidize DMP in the absence of H2O2. With some substrates, a strong inhibition of the peroxidative activity by Mn2+ was observed. Phenol red oxidation was inhibited by 84% with only 1 mM of this metal ion. Because DMP oxidation by this enzyme is only slightly inhibited by Mn2+, this substrate should not be used in assays to detect manganese peroxidase. The enzyme is tentatively named 'Manganese-Inhibited Peroxidase'.     

Stabilization of the nuclear matrix by disulfide bridges: identification of matrix polypeptides that form disulfides.

The molecular structure of the nuclear matrix is still poorly understood. We have tried to assess which proteins are important structural elements by examining the process of stabilization of the nuclear matrix by sodium tetrathionate. Sodium tetrathionate stabilizes the nuclear matrix by oxidizing sulfhydryl groups to disulfides. We show that tetrathionate-stabilized matrices are disassembled in buffers containing SDS, indicating that the stabilized nuclear matrix is not a continuous network of cross-linked proteins. Using monobromobimane, a thiol-specific fluorescent reagent, we show that many protein thiols in the stabilized matrix are oxidized. By chromatography on activated thiol-Sepharose we estimated that about 50% of the matrix proteins had oxidized sulfhydryl groups. The protein composition of the material bound to activated thiol-Sepharose was similar to that of the not-bound material. A few proteins are highly enriched in the fraction that was bound to the column. This indicates that many matrix protein species are partially oxidized and that some proteins are completely oxidized. The oxidized protein thiols are found in relatively large complexes as determined by SDS gel-electrophoresis under nonreducing conditions. These results are interpreted in terms of protein-protein interactions in the matrix. The possible role of thiols and disulfides in the in vivo organization of the nucleus is discussed.     

Induction of an organ-specific autoimmune disease, lymphocytic hypophysitis, in hamsters by recombinant rubella virus glycoprotein and prevention of disease by neonatal thymectomy.

Glycosylated, membrane-associated E1 (58-kDa) and E2 (47- to 49-kDa) rubella virus proteins and unglycosylated nucleoprotein C (33 kDa), from separately expressed vaccinia virus recombinants, were injected into golden Syrian hamsters. Rubella virus E1 and E2 glycoproteins consistently induced an organ-specific autoimmune disease, autoimmune lymphocytic hypophysitis, which was evidenced by the induction of autoantibodies against pituitary cells and by lymphocytic infiltration of the pituitary. Neonatal thymectomy prevented the disease. In contrast, rubella virus nucleoprotein C did not induce either autoantibodies against pituitary cells or lymphocytic infiltration of the pituitary. This finding raises the possibility that virus-specific protein itself can induce an organ-specific autoimmune disease in certain circumstances.     

Evolution of the V3 envelope domain in proviral sequences and isolates of human immunodeficiency virus type 1 during transition of the viral biological phenotype.

The third variable domain (V3) of the envelope gene of human immunodeficiency virus type 1 contains a major neutralization epitope and determinants of syncytium-inducing (SI) capacity and replication rate (reviewed by J. P. Moore and P. L. Nara, AIDS Suppl. 2:S21-S33, 1991). Sequences were generated from DNA of samples taken 3 months apart over a period of 24 and 30 months from peripheral blood mononuclear cells (PBMC) of two individuals, both before and after cocultivation with uninfected donor PBMC. The isolated virus shifted from the non-syncytium-inducing (NSI) phenotype to the SI phenotype during the study period. This shift was associated with distinct changes in the V3 domain in both patients. The association of the phenotype shift with the V3 sequence changes was confirmed by construction of viruses with chimeric V3 loops. The shift from NSI- to SI-associated V3 variants was also seen in the uncultured PBMC of both patients, but not until 3 and 9 months after the detection of SI virus in culture. In the samples of uncultured PBMC DNA, several subgroups of sequences were found, indicating that the process of evolution may not be gradual and that several distinct populations can coexist. The paucity of intermediate sequences indicated that strong selection pressure was exerted on this part of the envelope. The early emergence of disease-associated SI variants in cultured material indicates that virus culture may have relevance for the in vivo situation.     

The carboxy-terminal lysine of alpha B-crystallin is an amine-donor substrate for tissue transglutaminase.

A hexapeptide, corresponding to the sequence around the glutamine in beta A3-crystallin that functions as amine-acceptor for transglutaminase, was synthesized. This peptide was biotinylated and used as a probe to identify amine-donor substrates for transglutaminase among lens proteins. It was found that Ca(2+)-activated transglutaminase linked this peptide not only to several beta-crystallins but, unexpectedly, also to alpha B-crystallin. The C-terminal lysine residue of alpha B-crystalline could be identified as the site of linkage. This strengthens the notion that, at least in crystallins, all transglutaminase substrate residues are located in terminal extensions of the polypeptides. It was shown that in lens homogenate, alpha B-crystallin can be covalently crosslinked to beta-crystallins by transglutaminase. The transglutaminase-mediated crosslinking of alpha B-crystallin may have implications for its involvement in normal and pathological processes in lens and other tissues.     

Maturation- and differentiation-dependent responsiveness of human CD4+ T helper subsets.

The human CD45R0+ (memory) CD4+ T cell population can be subdivided into a large (82%) CD27+ and a small (18%) CD27- subset. Within the CD45R0+CD27- subset, cells accumulate that have been persistently stimulated by Ag in vivo. As an apparent consequence, TLC with a differentiated functional phenotype, producing either high levels of IFN-gamma (Th1-like), high levels of IL-4 (Th2-like) or high amounts of both these cytokines (here referred to as Thx) can primarily be generated from the CD27- memory CD4+ T cell subset. In this study we examined the requirements for induction of proliferation of distinct CD4+CD45R0+ Th subsets. Immobilized CD3 mAb induced proliferation with comparable magnitude and kinetics in all types of TLC. However, interference with intracellular signaling pathways in this activation system, resulted in a strong inhibition of proliferation in TLC derived from CD27+ cells whereas, in contrast, TLC from CD27- cells were relatively resistant to elevation of [cAMP]i, inhibition of protein kinase C activation and the immunosuppressive effects of cyclosporin A. Stimulation with CD3 mAb in soluble form resulted in Il-4 secretion by Th2-like and Thx-type TLC but did not induce IFN-gamma or Il-2 secretion in any Th subset. Interestingly, Th2-like cells but not Thx-type cells were able to use endogenously produced Il-4 for proliferation. These data demonstrate a differential sensitivity of CD45R0+CD4+ Th subsets for immune activation and suppression, which correlated with their maturation stage, as reflected by CD27 membrane expression, as well as with their effector phenotype.     

Platelet kinetics and other hematological profiles in experimental Plasmodium falciparum infection: a comparative study between Saimiri and Aotus monkeys.

Levels of platelets and other hematological values were monitored in 21 Saimiri and 12 Aotus monkeys over a period of three weeks post-infection with monkey-adapted Indochina CDC-1 strain of Plasmodium falciparum. In both Saimiri sciureus boliviensis and Aotus nancymai karyotype-1 monkeys the severest thrombocytopenia was observed at 14 days post-infection coinciding with peak parasitemia, neutropenia, lymphocytosis, and anemia associated with severe hemoglobinemia and elevated fibrinogen degeneration products(FDP's). MCH and MCV profiles in Aotus monkeys decreased with ascending parasitemia. In contrast, these parameters in Saimiri were characterized by a significant compensatory increase correlating with parasitemia. In general, thrombocytopenia was one of the earliest clinical manifestations of the infection with the platelets returning to normal levels shortly after peak parasitemia at 14 days. Platelet kinetics had a strong correlation with hematologic and parasitologic values in the Aotus model. No consistent associations were observed between platelet kinetics and other parameters in the Saimiri model. These data indicate that the Aotus model for malaria is more predictable than the Saimiri. Further, platelet turnover rates and recovery provide a useful prognostic parameter during malaria infection. The results are discussed in relation to the value of the two species of monkeys as models for the pathogenesis of human malaria.     

Plant size,geitonogamy and seed set in Ipomopsis aggregata

Summary We used powdered fluorescent dyes to estimate receipt of self vs. outcross pollen in the self-incompatible species Ipomopsis aggregata (Polemoniaceae). Flowers on small and large plants received equal amounts of outcross pollen, whereas flowers on large plants received more self pollen, so the proportion of self pollen delivered through geitonogamy increased with plant size. In natural populations emasculation of all flowers on a plant raised average seed set per flower from 5.19 to 6.99 and also raised fruit set, though not significantly. From these results one expects a negative correlation between plant size and seeds per flower. The opposite trend was observed in a sample of plants in the field, suggesting that deleterious effects of geitonogamy on female fecundity in large plants can be overruled by other factors such as size-related fruit or seed abortion. Results are discussed in relation to the evolution of gynodioecy.