Evaluating Retinal Function in Age-Related Maculopathy with the ERG Photostress Test

PURPOSE. To evaluate the diagnostic potential of the electroretinogram (ERG) photostress test and the focal cone ERG in age-related maculopathy (ARM). METHODS. The cohort comprised 31 patients with ARM and 27 age-matched control subjects. The ERG photostress test was used to monitor cone adaptation after intense light adaptation. Focal 41- and 5-Hz cone ERGs were recorded monocularly (central 20°) to assess steady state retinal function. Univariate analysis identified electrophysiological parameters that differed between groups, and receiver operating characteristic (ROC) curves were constructed to assess their diagnostic potential. Logistic regression analysis determined the diagnostic potential of a model incorporating several independent predictors of ARM. RESULTS. The rate of recovery of the ERG photostress test was reduced (recovery was slower) in subjects with ARM. The parameter exhibited good diagnostic potential (P = 0.002, area under ROC curve = 0.74). The implicit times of the 5-Hz (a-wave, P = 0.002; b-wave, P < 0.001) and the 41-Hz (P < 0.001) focal cone ERGs were increased, and the 41-Hz focal cone ERG amplitude (P = 0.003) and focal to full-field amplitude ratio (P = 0.001) were reduced in the ARM group. Logistic regression analysis identified three independent predictors of ARM, including the rate of recovery of the ERG photostress test. CONCLUSIONS. Early ARM has a marked effect on the kinetics of cone adaptation. The clinical application of the ERG photostress test increases the sensitivity and specificity of a model for the diagnosis of ARM. Improved assessment of the functional integrity of the central retina will facilitate early diagnosis and evaluation of therapeutic interventions

Treatment with octreotide to suppress corticotropin secretion by a carcinoid tumour

Ectopic secretion of corticotropin (ACTH) by a tumour is most likely to respond to somatostatin analogues if hypercortisolaemia has not yet developed

Patient progress modelling and results in Wilm's Tumour

The report describes the development of a mathematical model of the progress of patients with Wilm's Tumour using the methodology developed by Jackson & Aspden [1, 2]. The model incorporates two prognostic factors which are shown to influence patient progress. These are the stage of the tumour and the age of the patient at presentation. The model proved adequate to represent an initial set of patient data, and comparison runs were performed with data from a later time period. These runs highlighted changes in patient progress between the two groups and illustrated the usefulness of the model in this type of analysis. The analysis also underlined the poor prognosis of patients over 5 years old who relapsed.

Geochemistry and origin of listwanites in the Sartohay and Luobusa ophiolites, China

Gold-bearing listwanites of the Sartohay ophiolite, northwestern China, consist mainly of tale, magnesite, chlorite, quartz, and dolomite, locally accompanied by chromian mica (fuchsite). They formed along NE-trending faults by hydrothermal alteration of serpentinized peridotites. The original protoliths were clinopyroxene-bearing harzburgites and lherzolites containing relatively aluminous magnesiochromite. Compared to their protoliths, listwanites generally have lower MgO and significantly higher CaO, TiO 2, and total rare-earth elements. Gold mineralization occurs chiefly in large quartz veins with grades up to several tens of g/t. Listwanites in the Luobusa ophiolite, Tibet, form a narrow band along the southern boundary fault of the ophiolite. Some of these listwanites have relict textures, suggesting derivation from serpentinized peridotite; however, adjacent harzburgites and clinopyroxene-bearing harzburgites are very fresh, with less than 1% serpentinization. The Luobusa listwanites consist essentially of talc and magnesite with lesser amounts of quartz. Most are indistinguishable geochemically from the unserpentinized protoliths except for having notably higher loss on ignition. None of these rocks are mineralized. The Sartohay listwanites are spatially associated with granitic intrusions dated at 301 Ma. They were altered by relatively high temperature fluids, as indicated by homogenization temperatures of fluid inclusions in quartz ranging from 340 to 360°C. Those in the Luobusa ophiolite are not associated with any known igneous activity and are believed to have formed at somewhat lower temperatures. Although both varieties are completely altered and have generally similar mineral assemblages, only those of Sartohay show significant geochemical modification and gold mineralization. Both types have been moderately silicified and are easily recognized by their light brown color and resistant outcrops. Copyright © 2005 by V. H. Winston & Son, Inc. All rights reserved.link_to_subscribed_fulltex

Melt/mantle interaction and melt evolution in the Sartohay high-Al chromite deposits of the Dalabute ophiolite (NW China)

The Sartohay block of the Dalabute ophiolite consists chiefly of mantle harzburgite and lherzolite with minor dunite. These rocks host voluminous chromite deposits with lenticular or vein-like shapes. The podiform chromitites are associated with, and cross-cut by, numerous troctolite dykes. Chromite in the chromitites has Al 2O 3 (23-31 wt%). TiO 2 (0.29-0.44 wt%). and Cr 2O 3 contents (<45 wt%) with Cr#s [100Cr/(Cr + Al)] (<60), typical of high-Al chromite deposits. The host peridotites in Sartohay have been texturally and geochemically modified by magmas from which the high-Al chromitites and mafic dykes formed. Dunites commonly envelop the podiform chromite bodies and show transitional contacts with the peridotites. Some of the peridotites and chromitites contain plagioclase that crystallized from impregnated melts. The dunite locally grades into troctolite with increasing plagioclase contents. As a result of melt impregnation, peridotites and dunites show variable Ca and Al contents and LREE enrichment. The parental magma of the chromitites was likely tholeiitic in composition, derived from partial melting of the asthenospheric mantle in a rising diapir. The interaction between this magma and pre-existing lithospheric mantle, composed of depleted lherzolite, would have formed a more silicic, tholeiitic magma from which high-Al chromitites crystallized. During this interaction, harzburgite and dunite were depleted in modal pyroxene and enriched in some incompatible elements (such as Al, Ca and LREE) due to melt impregnation. © 2001 Elsevier Science Ltd. All rights reserved.link_to_subscribed_fulltex