1st radiometric dating of a paleontologically dated Bathonian level from Georgia (USSR) - Use of the cathodoluminescence for selection of suitable plagioclases

Jurassic volcanic formations interlayered with (ammonite-bearing) sediments are common in the Caucasus area; this situation is of interest for the numerical calibration of the poorly documented Jurassic portion of the time scale. However, following petrographic study on thin sections no whole-rocks can be considered reliable geochronometers due to subsequent alteration; from about 20 samples, two were selected for plagioclase dating; one (V134) is probably early Kimmeridgian in age; the other (V136) is probably located in the Lower Bathonian stage according to diagnostic ammonites. Cathodoluminescence (CTL) study has shown that sample V136 was similar to usual volcanic feldspars (blue to green colour); however, the lack of CTL of the V134 plagioclase is a character common to diagenetic feldspars; consequently, in spite of a good optical preservation, this geo-chronometer cannot give an age representative of the time of emplacement of the lava flow. We have combined CTL observation with microprobe analysis in order to document the poorly known CTL behaviour of volcanic feldspars; cations Ti4+ and Fe2+ play a major role in the CTL colour of plagioclases and are able to document the growing history of these feldspars ; phenocrysts are initially rich in Fe2+ (core of the crystals, green in colour), then richer in Ti toward the exterior; microcrysts are even richer in Ti (blue to bright blue). We have also observed that natural CTL colour was modified resulting from acid ``cleaning'' of the separated feldspars : the initial blue or green colour tends to change to yellow or violet, respectively, after acid treatment probably due to oxydation of Fe2+ toward Fe3+. X-ray and microprobe analyses both indicated that plagioclases from sample V134 was near the sodic end member (albite) suggesting a diagenetic origin in this andesitic basalt; In contrast, sample V136 contains a calcic plagioclase of common composition for a doleritic basalt. The K-Ar conventional technique was applied as a preliminary tool for radiometric analysis. The Kimmeridgian Na-plagioclase sample gave a ``rejuvenated'' (85 Ma) apparent age which confirms a late genesis for the separated plagioclase phase; this interpretation is based on CTL observation, X-ray analysis, and microprobe analysis ; these techniques are able to distinguish samples which have been submitted to diagenetic alteration from those which have not. An age consistent with the stratigraphic location has been obtained from sample V136. This age of 161 +/- 3 (2-sigma) Ma, is the first one available from a sample palaeontologically located with reasonable precision within the mid Jurassic time.

Recent developments in the use of isotope ratio mass spectrometry in sports drug testing.

According to the annual report of the World Anti-Doping Agency, steroids are the most frequently detected class of doping agents. Detecting the misuse of endogenously occurring steroids, i.e. steroids such as testosterone that are produced naturally by humans, is one of the most challenging issues in doping control analysis. The established thresholds for urinary concentrations or concentration ratios such as the testosterone/epitestosterone quotient are sometimes inconclusive owing to the large biological variation in these parameters.For more than 15 years, doping control laboratories focused on the carbon isotope ratios of endogenous steroids to distinguish between naturally elevated steroid profile parameters and illicit administration of steroids. A variety of different methods has been developed throughout the last decade and the number of different steroids under investigation by isotope ratio mass spectrometry has recently grown considerably. Besides norandrosterone, boldenone was found to occur endogenously in rare cases and the misuse of corticosteroids or epitestosterone can now be detected with the aid of carbon isotope ratios as well. In addition, steroids excreted as sulfoconjugates were investigated, and the first results regarding hydrogen isotope ratios recently became available.All of these will be presented in detail within this review together with some considerations on validation issues and on identification of parameters influencing steroidal isotope ratios in urine.

Développement, implémentation et utilisation pratique d'un score diagnostique [Development, implementation and practical use of a diagnostic score].

In recent years many clinical prediction rules (CPR) have been developed. Before a CPR can be used in clinical practice, different methodical steps are necessary, from the development of the score, the internal and external validation to the impact study. Before using a CPR in daily practice family doctors have to verify how the rules have been developed and whether this has been done in a population similar to the population in which they would use them. The aim of this paper is to describe the development of a CPR, and to discuss advantages and risks related to the use of CPR in order to help family doctors in their choice of scores for use in their daily practice.

Use of long-term suppressive acyclovir after hematopoietic stem-cell transplantation: impact on herpes simplex virus (HSV) disease and drug-resistant HSV disease.

The effect that long-term use of suppressive acyclovir (ACV) has on both overall herpes simplex virus (HSV) disease and ACV-resistant HSV disease was examined in 3 consecutive cohorts of hematopoietic stem-cell transplant (HCT) recipients (n=2049); cohort 1 received ACV for 30 days after HCT, cohort 2 received it for 1 year after HCT, and cohort 3 received it for an extended period (i.e., >1 year) if the patient's immunosuppression continued after 1 year. The 2-year probability of HSV disease was 31.6% (95% confidence interval [CI], 28.0%-35%) in cohort 1, 3.9% (95% CI, 2.7%-5.2%) in cohort 2, and 0% in cohort 3 (P<.001). ACV-resistant HSV disease developed in 10 patients in cohort 1 (2-year probability, 1.3% [95% CI, 0.8%-2.7%]), in 2 patients in cohort 2 (2-year probability, 0.2% [95% CI, 0%-0.8%]; P=.006), and in 0 patients in cohort 3 (cohort 2 vs. cohort 3, P=.3). Long-term use of suppressive prophylactic ACV appears to prevent the emergence of drug-resistant HSV disease in HCT.

Use of recombinant tissue plasminogen activator in children with meningococcal purpura fulminans: a retrospective study.

OBJECTIVE: Meningococcal disease causes septic shock with associated disseminated intravascular coagulation and hemorrhagic skin necrosis. In severe cases, widespread vascular thrombosis leads to gangrene of limbs and digits and contributes to morbidity and mortality. Uncontrolled case reports have suggested that thrombolytic therapy may prevent some complications, and the use of tissue plasminogen activator (t-PA) has been widespread. Our aim was to summarize the clinical outcome and adverse effects where systemic t-PA has been used to treat children with fulminant meningococcemia. DESIGN: International, multiple-center, retrospective, observational case note study between January 1992 and June 2000. SETTING: Twenty-four different hospitals in seven European countries and Australia. PATIENTS: A total of 62 consecutive infants and children with severe meningococcal sepsis in whom t-PA was used for the treatment of predicted amputations and/or refractory shock (40 to treat severe ischemia, 12 to treat shock, and ten to treat both). INTERVENTIONS: t-PA was administered with a median dose of 0.3 mg.kg(-1).hr(-1) (range, 0.008-1.13) and a median duration of 9 hrs (range, 1.2-83). MAIN RESULTS: Twenty-nine of 62 patients died (47%; 95% confidence interval, 28-65). Seventeen of 33 survivors had amputations (11 below knee/elbow or greater loss; six less severe). In 12 of 50 patients to whom t-PA was given for imminent amputation, no amputations were observed. Five developed intracerebral hemorrhages (five of 62, 8%; 95% confidence interval, 0.5-16). Of these five, three died, one developed a persistent hemiparesis, and one recovered completely. CONCLUSIONS: The high incidence of intracerebral hemorrhage in our study raises concerns about the safety of t-PA in children with fulminant meningococcemia. However, due to the absence of a control group in such a severe subset of patients, whether t-PA is beneficial or harmful cannot be answered from the unrestricted use of the drug that is described in this report. Our experience highlights the need to avoid strategies that use experimental drugs in an uncontrolled fashion and to participate in multiple-center trials, which are inevitably required to study rare diseases.

ITMIG consensus statement on the use of the WHO histological classification of thymoma and thymic carcinoma: refined definitions, histological criteria, and reporting.

INTRODUCTION: The 2004 version of the World Health Organization classification subdivides thymic epithelial tumors into A, AB, B1, B2, and B3 (and rare other) thymomas and thymic carcinomas (TC). Due to a morphological continuum between some thymoma subtypes and some morphological overlap between thymomas and TC, a variable proportion of cases may pose problems in classification, contributing to the poor interobserver reproducibility in some studies. METHODS: To overcome this problem, hematoxylin-eosin-stained and immunohistochemically processed sections of prototypic, "borderland," and "combined" thymomas and TC (n = 72) were studied by 18 pathologists at an international consensus slide workshop supported by the International Thymic Malignancy Interest Group. RESULTS: Consensus was achieved on refined criteria for decision making at the A/AB borderland, the distinction between B1, B2, and B3 thymomas and the separation of B3 thymomas from TCs. "Atypical type A thymoma" is tentatively proposed as a new type A thymoma variant. New reporting strategies for tumors with more than one histological pattern are proposed. CONCLUSION: These guidelines can set the stage for reproducibility studies and the design of a clinically meaningful grading system for thymic epithelial tumors.

The use of ISO 9001 quality standard in higher education institution libraries

[eng] ISO standard 9001 is one of a set of management tools that libraries have adopted in recent years. This article focuses on libraries in higher education institutions that have received ISO certification of their quality management systems (ISO standard 9001:2000). We examine their reasons for seeking certification and the advantages and difficulties they have encountered in applying this ISO standard. Finally, we consider the future prospects of ISO standard 9001 in university libraries.

Prophylactic use of bevacizumab to avoid anterior segment neovascularization following proton therapy for uveal melanoma.

PURPOSE: To investigate whether the prophylactic use of bevacizumab reduces the rate of rubeosis after proton therapy for uveal melanoma and improves the possibility to treat ischemic, reapplicated retina with laser photocoagulation. DESIGN: Comparative retrospective case series. METHODS: Uveal melanoma patients with ischemic retinal detachment and treated with proton therapy were included in this institutional study. Twenty-four eyes received prophylactic intravitreal bevacizumab injections and were compared with a control group of 44 eyes without bevacizumab treatment. Bevacizumab injections were performed at the time of tantalum clip insertion and were repeated every 2 months during 6 months, and every 3 months thereafter. Ultra-widefield angiography allowed determination of the extent of retinal ischemia, which was treated with laser photocoagulation after retinal reapplication. Main outcome measures were the time to rubeosis, the time to retinal reattachment, and the time to laser photocoagulation of ischemic retina. RESULTS: Baseline characteristics were balanced between the groups, except for thicker tumors and larger retinal detachments in the bevacizumab group, potentially to the disadvantage of the study group. Nevertheless, bevacizumab prophylaxis significantly reduced the rate of iris rubeosis from 36% to 4% (log-rank test P = .02) and tended to shorten the time to retinal reapplication until laser photocoagulation of the nonperfusion areas could be performed. CONCLUSIONS: Prophylactic intravitreal bevacizumab in patients treated with proton therapy for uveal melanoma with ischemic retinal detachment prevented anterior segment neovascularization, until laser photocoagulation to the reapplied retina could be performed.