Radiocarbon dating of deep-sea corals

Deep-sea corals are a promising new archive of paleoclimate. Coupled radiocarbon and U-series dates allow ^(14)C to be used as a tracer of ocean circulation rate in the same manner as it is used in the modern ocean. Diagnetic alteration of coral skeletons on the seafloor requires a thorough cleaning of contaminating phases of carbon. In addition, 10% of the coral must be chemically leached prior to dissolution to remove adsorbed modern CO_2. A survey of modern samples from the full Δ^(14)C gradient in the deep ocean demonstrates that the coralline CaCO_3 records the radiocarbon value of the dissolved inorganic carbon

Ubiquinone-8 Stimulates Phagocytosis in Macrophages by Modulation of the Kinetics of the Fc Receptor

The effect of exogenous ubiquinone-8 (Q8) on IgG- and C3b-mediated phagocytosis of sensitized sheep red blood cells and of opsonized Staphylococcus aureus by macrophages was studied by morphological and quantitative methods. Q8 stimulated the initial events of phagocytosis, that is, attachment and ingestion, in which occupancy of the Fe receptor by IgG was shown to be of critical significance. The kinetics of competitive inhibition of phagocytosis of opsonized bacteria by macrophages by using Fe fragments suggested the intimate role of the kinetics of the Fe receptor in the initial events of phagocytosis and, further, the modulation of the kinetics of the Fe receptor by Q8 as the basis of enhanced phagocytosis by Q

Editorial

The Tenth International Conference on Accelerator Mass Spectrometry (AMS-10) was held from September 5-10 at the University of California, Berkeley campus. The conference attracted 305 attendees from 26 countries who gave 144 platform presentations and presented a total of 170 posters. The conference opened with a special tribute to the late Roy Middleton, which was followed by a companion session on 'ion sourcery'. A plenary talk by Wally Broecker on his '53 years in the Radiocarbon Trenches', provided thought-provoking challenges to commonly accepted paradigms. A workshop on issues in the estimation of isotopic ratios and evaluations of activities from AMS measurements preceded the conference and a workshop on AMS in low-dose bioscience concluded it. Conference attendees had ample opportunity to sample local sights and mid-week excursions to the Napa Valley wine region and the Monterey Bay Aquarium were well attended. The social highlight of the conference was a dinner cruise on San Francisco Bay aboard the San Francisco Belle, which toured the bay on a clear evening and afforded spectacular views of the city front as well as the Bay and Golden Gate bridges. The proceedings of AMS-10 contain 140 peer-reviewed papers that detail recent developments in AMS technology and a broad range of scientific applications. The editors worked to ensure that these contributions represent original research that has not been published elsewhere. We are grateful to the many outside reviewers who provided thoughtful consideration and suggestions in their reviews of these manuscripts. The staff of the Center for Accelerator Mass Spectrometry at the Lawrence Livermore National Laboratory wishes to thank the many members of the international AMS community in allowing us to organize this conference. We are particularly grateful to the University of California's Toxic Substances Research Program, which provided key assistance with conference administration

Sources and cycling of dissolved and particulate organic radiocarbon in the northwest Atlantic continental margin

Continental shelves and slopes are productive and dynamic ocean margin systems that also regulate the fluxes of terrestrial, riverine, and estuarine materials between the continents and oceans. In order to evaluate the ages, potential sources, and transformations of organic matter in an ocean margin system, we measured the radiocarbon (Delta (14)C and delta (13)C distributions of total dissolved organic carbon (DOC), suspended particulate organic carbon (POC), and dissolved inorganic carbon (DIC) in waters of the Middle Atlantic Bight (MAB) continental shelf and slope in April-May 1994. The Delta (14)C of DOC was greatest (as high as -39 parts per thousand) in surface waters of the shelf, decreasing rapidly offshore and with depth, even in relatively shallow (25-50 in depth) shelf waters. The lowest Delta (14)C-DOC values were observed in deep slope waters, where they were significantly lower than values measured previously for the deep Sargasso Sea. There was a strong inverse relationship between Delta (14)C-DOC and delta (-13)C-DOC in all shelf and surface slope waters of the MAB, which is likely attributable to varying contributions of young, (14)C-enriched organic matter of terrestrial and/or riverine origin. The more highly (14)C-depleted DOC in deep : slope waters (as low as -442 parts per thousand) generally had a correspondingly lower delta (13)C (as low as -22.3 parts per thousand) component. However, this must originate from relic terrestrial material either in the MAB itself or be discharged to the MAB from rivers and estuaries. The isotopic signatures of POC were clearly differentiable from DOC and indicate that this pool also contained a broad range of both old and young material of terrestrial (delta (13)C as low as -24.9 parts per thousand) and marine (delta (13)C as high as -19.9 parts per thousand) origin throughout the MAB shelf and slope. The highest Delta (14)C-POC values (up to 78 parts per thousand) were observed in shallow shelf waters of the southern MAR Conversely, the lowest Delta (14)C-POC values (as low as -394 parts per thousand) were found in MAB deep slope waters and were also significantly more depleted in (14)C than POC from the central north Atlantic (Sargasso Sea). A multiple-source isotopic mass balance model employing both (14)C and (13)C was used to evaluate the relative contributions of both young and old terrigenous versus marine organic matter to DOC and POC in the MAR The results indicate that shelf and slope DOC is comprised of an old marine fraction (represented by offshore Sargasso Sea material) and either a young terrestrial/riverine/estuarine (TRE) component (in shelf and shallow slope waters) or a relic TRE component (in deep and some shallow slope waters). In contrast, suspended POC from the MAB appears to originate predominantly from a mixture of recent MAB primary production and an old, TRE component, similar to that observed in one of the major subestuaries of the Chesapeake Bay. These results suggest that both young and old sources of terrestrial and riverine organic matter can comprise a significant fraction of the DOC and POC in ocean margins. Preliminary calculations indicate that the export of this compositionally unique DOC and suspended POC may be significant terms in the organic carbon budgets of the MAB and other margin systems

Mechanisms of progression of chronic kidney disease

Chronic kidney disease (CKD) occurs in all age groups, including children. Regardless of the underlying cause, CKD is characterized by progressive scarring that ultimately affects all structures of the kidney. The relentless progression of CKD is postulated to result from a self-perpetuating vicious cycle of fibrosis activated after initial injury. We will review possible mechanisms of progressive renal damage, including systemic and glomerular hypertension, various cytokines and growth factors, with special emphasis on the renin–angiotensin–aldosterone system (RAAS), podocyte loss, dyslipidemia and proteinuria. We will also discuss possible specific mechanisms of tubulointerstitial fibrosis that are not dependent on glomerulosclerosis, and possible underlying predispositions for CKD, such as genetic factors and low nephron number