Improvement of cast nephropathy with plasma exchange depends on the diagnosis and on reduction of serum free light chains

Cast nephropathy is the most common cause of renal disease in multiple myeloma, however, treatment with plasma exchange remains controversial even after 3 randomized controlled studies. We sought to determine the importance of diagnostic confirmation and goal directed therapy in the treatment of cast nephropathy in forty patients with confirmed multiple myeloma and renal failure who underwent plasma exchange. A positive renal response was defined as a decrease by half in the presenting serum creatinine and dialysis independence. No baseline differences were noted between eventual renal responders and non-responders. Three quarters of the patients with biopsy proven cast nephropathy resolved their renal disease when the free light chains present in the serum were reduced by half or more but there was no significant response when the reduction was less. The median time to a response was about 2 months. In patients without cast nephropathy, renal recovery occurred despite reductions in free light chain levels of the serum. No association was found between free light chains in the serum, urinary monoclonal proteins, overall proteinuria and cast nephropathy. We found that the relationship between renal recovery and free light chain reduction was present only in patients with biopsy proven cast nephropathy showing the importance of extracorporeal light chain removal in this disease

An active mantle mechanism for Gondwana breakup

Despite over thirty years of plate tectonic theory, the reasons why supercontinents like Gondwana disintegrate into smaller continents and disperse remain enigmatic. Current ideas mostly involve changes in plate-boundary driving forces (passive mantle hypothesis) in preference to an active plume mechanism, even though mantle plumes were present at most stages of Gondwana breakup. The role of these plumes in the breakup process is uncertain, and ideas vary from the chance unroofing of a pre-existing plume, which only contributed in the production of extensive flood basalts, to plumes that controlled the position of breakup. The magmatic and tectonic record along the proto-Pacific margin of Gondwana indicates that there were important changes in subduction zone forces during the initial stages of Gondwana breakup. However, the absence of subduction along the Neotethyan margin at the time of breakup, together with the fact that the initial rift formed almost at right angles to the active subducting margin, suggest a potential active role for a mantle plume in the initial separation. An active mantle mechanism, involving a very large thermal disturbance or megaplume, may, in contrast to a passive mantle hypothesis, more readily explain the formation and rotation of microplates in the South Atlantic region. It accounts also for the production of unusually large igneous provinces (Chon Aike province in Patagonia, Karoo province in southern Africa, and Ferrar province in Antarctica) just prior to breakup

VOLCANIC GEOLOGY OF MOUNT EREBUS, ROSS ISLAND, ANTARCTICA

Mount Erebus is an active volcano located on Ross Island, Antarctica, in an intraplate extensional tectonic setting. Reconnaissance geologic mapping has shown Mt. Erebus to be composed predominantly of anorthoclase phonolite lava flows and associated pyroclastic rocks. At the surrounding areas of Fang Ridge, Dellbridge Islands, Turks Head and Cape Barne, the lava flows and various pyroclastic deposits are predominantly intermediate in composition. Most of the lavas from Erebus and surroundings are strongly undersaturated and sodic, forming a continuous differentiation lineage consisting of basanite, Ne-hawaiite, Ne-mugearite, Ne-benmoreite and anorthoclase phonolite. These lavas are termed the Erebus lineage (EL) and are predominantly coarsely porphyritic with a similar phenocryst assemblage consisting of olivine, clinopyroxene, opaque oxides, feldspar, apatite and rare feldspathoids.EL lavas are distinctly different from the lavas of the three predominantly basanite volcanic centers which radially surround Mt. Erebus (DVDP lineage; P.R. KYLE : J. Petrol., 22,451,1981), and must have a different petrogenesis. Very minor volumes of less undersaturated benmoreite, phonolite and trachyte occur on Mt. Erebus and must also have evolved independently of the EL

Preliminary lithofacies assessment and 40Ar/39Ar ages of Cenozoic volcanic sequences in eastern Marie Byrd Land

Because of its remoteness, Marie Byrd Land is among the most inaccessible and least visited parts of Antarctica. However, it contains a very poorly studied, large Cenozoic alkaline volcanic province and an outstanding record of volcanism coeval with glaciation (LeMasurier & Thomson 1990). This short note describes the results of the second of two planned periods of fieldwork, which form part of the West Antarctic Volcano Exploration (WAVE) project. The background to WAVE and preliminary results of the 1989–1990 fieldwork are described in Smellie et al. (1990) and McIntosh et al. (1990). The studies described here took place between 2 November 1990 and 11 January 1991

Volcanoes of the Antarctic Plate and Southern Ocean

This volume attempts to present both a comprehensive overview of the south polar and subpolar volcanic provinces, and summary data on the status of knowledge of each volcano or volcano group. This broad region, covering roughly 6% of the Earth's surface, is infrequently visited and yet truly international. Its geoscience literature is dispersed in many journals, monographs, symposium volumes, and expedition reports, in many nations, and we hope that this summary will make it more widely available. The preparation of the volume has been a project of the International Association of Volcanology and Chemistry of the Earth's Interior (IAVCEI) through its Working Group on Antarctic Volcanology. It represents a substantial update and expansion of IAVCEI's 1960 Catalogue of Active Volcanoes for Antarctica (edited by W.H. Berninghausen and M. Neumann van Padang)