Hailey-Hailey disease (HHD, MIM 16960) is inherited in an autosomal dominant manner and characterized by persistent blisters and erosions of the skin. Impaired intercellular adhesion and epidermal blistering also occur in individuals with pemphigus (which is due to autoantibodies directed against desmosomal proteins) and in patients with Darier disease (DD, MIM 124200), which is caused by mutations in a gene encoding a sarco/endoplasmic reticulum (ER)-Golgi calcium pump. We report here the identification of mutations in ATP2C1, encoding the human homologue of an ATP-powered pump that sequesters calcium into the Golgi in yeast, in 21 HHD kindreds. Regulation of cytoplasmic calcium is impaired in cultured keratinocytes from HHD patients, and the normal epidermal calcium gradient is attenuated in vivo in HHD patients. Our findings not only provide an understanding of the molecular basis of HHD, but also underscore the importance of calcium control to the functioning of stratified squamous epithelia.
The growth of accelerator mass spectrometry as a tool for quantitative isotope ratio analysis in the biosciences necessitates high-throughput sample preparation. A method has been developed to convert CO(2) obtained from carbonaceous samples to solid graphite for highly sensitive and precise (14)C quantification. Septa-sealed vials are used along with commercially available disposable materials, eliminating sample cross contamination, minimizing complex handling, and keeping per sample costs low. Samples containing between 0.25 and 10 mg of total carbon can be reduced to graphite in approximately 4 h in routine operation. Approximately 150 samples per 8-h day can be prepared by a single technician.
[1] Fine particulate matter collected at two urban, four near-urban, and six remote sites throughout the United States were analyzed for total carbon (TC) and radiocarbon ( 14 C). Samples were collected at most sites for both a summer and winter season. The radiocarbon was used to partition the TC into fossil and contemporary fractions. On average, contemporary carbon composed about half of the carbon at the urban, $70-97% at near-urban, and 82-100% at remote sites. At Phoenix, Arizona, and Seattle, Washington, one monitor was located within the urban center and one outside to assess the urban excess over background concentrations. During the summer the urban and rural sites had similar contemporary carbon concentrations. However, during the winter the urban sites had more than twice the contemporary carbon measured at the neighboring sites, indicating anthropogenic contributions to the contemporary carbon. The urban fossil carbon was 4-20 times larger than the neighboring rural sites for both seasons. Organic (OC) and elemental carbon (EC) from TOR analysis were available. These and the radiocarbon data were used to estimate characteristic fossil and contemporary EC/TC ratios for the winter and summer seasons. These ratios were applied to carbon data from the Interagency Monitoring of Protected Visual Environments network to estimate the fraction of contemporary carbon at mostly rural sites throughout the United States. In addition, the ratios were used to develop a semiquantitative, lower bound estimate of secondary organic carbon (SOC) contribution to fossil and contemporary carbon. SOC accounted for more than one-third of the fossil and contemporary carbon.
Plasmodium falciparum is unable to synthesize purine bases and relies upon purine salvage and purine recycling to meet its purine needs. We report that purines formed as products of polyamine synthesis are recycled in a novel pathway in which 5 -methylthioinosine is generated by adenosine deaminase. The action of P. falciparum purine nucleoside phosphorylase is a convergent step of purine salvage, converting both 5 -methylthioinosine and inosine to hypoxanthine. We used accelerator mass spectrometry to verify that 5 -methylthioinosine is an active nucleic acid precursor in P. falciparum. Prior studies have shown that inhibitors of purine salvage enzymes kill malaria, but potent malaria-specific inhibitors of these enzymes have not been described previously. 5 -Methylthio-immucillin-H, a transition state analogue inhibitor that is selective for malarial relative to human purine nucleoside phosphorylase, kills P. falciparum in culture. Immucillins are currently in clinical trials for other indications and may also have application as anti-malarials.
Epidermal permeability barrier homeostasis requires the delivery of lipids and hydrolytic enzymes by lamellar body exocytosis from the uppermost granular cells, a process that is upregulated following barrier disruption. As lamellar body secretion is controlled by ionic concentrations, especially Ca2+ and K+, we used a quantitative technique, microbeam proton-induced X-ray emission, to measure Ca2+, K+, Cl-, and P concentrations before and after acute barrier perturbation by acetone applications. We found a steep gradient of Ca2+ in normal tissue, peaking in the outer stratum granulosum, which disappeared after barrier disruption, and partially reformed as the barrier recovered. A similar gradient, peaking somewhat lower in the epidermis (i.e., at the stratum granulosum-stratum corneum interface), was found for K+. Epidermal concentrations of K+ also decreased after barrier abrogation, although to a lesser extent than Ca2+. In contrast, P and Cl- demonstrated distribution gradients at baseline, which remained unchanged after barrier disruption. These studies quantitate the levels of Ca2+, K+, Cl-, and P within specific epidermal cell layers at baseline, and in relation to changes in permeability barrier integrity. Ca2+ and K+, but not Cl- or P, decrease after barrier disruption, consistent with these two ion's role in barrier repair.
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