Ecthyma gangrenosum secondary to Staphylococcus aureus in an infant with transient neutropenia.

Ecthyma gangrenosum is classically a cutaneous manifestation of a pseudomonal septicemia that presents in a patient with an immunodeficiency or hematologic malignancy. We describe a previously healthy 8-month-old girl who developed transient neutropenia and characteristic ecthyma gangrenosum lesions secondary to methicillin-resistant Staphylococcus aureus. This unique presentation of methicillin-resistant Staphylococcus aureus ecthyma gangrenosum emphasizes the importance of broad empiric coverage and early culturing for microorganism and susceptibilities in any patient presenting with ecthyma gangrenosum.

CD4+/CD56+ Hematodermic neoplasm (plasmacytoid dendritic cell tumor).

A 60-year-old male presented with multiple, purplish-red, nodules and plaques. After a complete work-up, he was diagnosed with CD4+/CD56+ hematodermic neoplasm. We review the clinical, pathological, and immunohistochemical features of this disease.

Basal body duplication and maintenance require one member of the Tetrahymena thermophila centrin gene family.

Centrins, small calcium binding EF-hand proteins, function in the duplication of a variety of microtubule organizing centers. These include centrioles in humans, basal bodies in green algae, and spindle pole bodies in yeast. The ciliate Tetrahymena thermophila contains at least four centrin genes as determined by sequence homology, and these have distinct localization and expression patterns.

Tyrosine-sulfated peptides functionally reconstitute a CCR5 variant lacking a critical amino-terminal region.

Entry of most primary human immunodeficiency virus, type 1 (HIV-1) isolates into their target cells requires the cellular receptor CD4 and the G protein-coupled chemokine coreceptor CCR5. An acidic, tyrosine-rich, and tyrosine-sulfated domain of the CCR5 amino terminus plays a critical role in the ability of CCR5 to serve as an HIV-1 coreceptor, and tyrosine-sulfated peptides based on this region physically associate with the HIV-1 envelope glycoprotein gp120 and slow HIV-1 entry into CCR5-expressing cells. Here we show that the same tyrosine-sulfated peptides, but not their unsulfated analogs, can restore the HIV-1 coreceptor activity of a CCR5 variant lacking residues 2-17 of its amino terminus.

Kinetic characterization of wild-type and proton transfer-impaired variants of beta-carbonic anhydrase from Arabidopsis thaliana.

We have cloned and overexpressed a truncated, recombinant form of beta-carbonic anhydrase from Arabidopsis thaliana. The wild-type enzyme and two site-directed variants, H216N and Y212F, have been kinetically characterized both at steady state by stopped-flow spectrophotometry and at chemical equilibrium by (18)O isotope exchange methods. The wild-type enzyme has a maximal k(cat) for CO2 hydration of 320 ms(-1) and is rate limited by proton transfer involving two residues with apparent pK(a) values of 6.