Chemical Composition of an Unusual Xenolith of the Allende Meteorite

The chemical composition of an unusual xenolith (All-AF) from the Allende meteorite was determined by neutron activation and x-ray fluorescence analyses. The xenolith is similar in bulk composition to Allende, but has large excesses in some moderately volatile trace elements, such as Na, K, Au, Sb etc. Some of these elements show considerable variations in other components of Allende, suggesting inhomogeneous distribution in Allende. However, elements of higher volatility, such as Zn and Se have concentrations typical of bulk Allende and other type 3 carbonaceous chondrites. Therefore, All-AF must have formed from the same reservoir as bulk Allende.

All-AF has uniform grain size and does not, and did never, contain chondrules. The low content of volatile elements, therefore cannot be ascribed to loss of volatiles during the chondrule forming process. It is a characteristic of the Allende reservoir. The chemical composition of related dark inclusions (DIs) in Allende is different from All-AF. Dark inclusions may have formed by separation of fine grained material in the early solar nebula while All-AF resembles bulk Allende material that was never subject to chondrule formation. Both, dark inclusions and All-AF have oxygen isotopic compositions which plot at the upper end of the δ18O vs. δ17O correlation, suggesting extensive oxygen exchange with ambient gas.

Allende Xenolith AF: Undisturbed Record of Condensation and Aggregation of Matter in the Solar Nebula

Allende-AF (All-AF) is chemically similar to bulk Allende, its texture is. however, completely different. It consists mainly of highly porous silicate-rich aggregates embedded in a largely opaque matrix. Occasionally olivine-sulfide-metal aggregates and large sulfide-andradite objects are found. Chondrules are absent and grain size in matrix and aggregates is the same, quite different from normal Allende.

The main mineral in All-AF is olivine (22-41 wt% FeO). low Ca-pyroxene is absent, but a variety of clinopyroxenes were encountered. Rare phases found throughout All-AF are refractory metal nuggets (Ir, Os, Ru etc.), HgS, and Ca-phosphate. Associated with sulfide-andradite objects are native-Cu, Ti-magnetite, perovskite, barite, and calcite.

Morphology, crystalline state and minor element contents of olivine strongly suggest an origin by condensation from a gas. Al20 3-contents, for example, range from 0.5 to 3% and Cr2O3-contents reach 2.5%.

Texture of All-AF indicates that condensation of olivine continued during formation of aggregates. Relictic low-Fe aluminous diopsides suggest that olivine was initially FeO-poor. Before final accretion into a solid rock exchange reactions between condensed phases and an (increasingly oxidized) vapor established the high FeO-content of olivine. A similar process led to sulfurization of most of the original metal. The exotic sulfide-andradite objects are probably alteration products of unusual, metal-rich calcium-aluminium-rich inclusions.

It appears that All-AF has preserved a unique record of condensation, hierarchical aggregation, and metasomatic exchange reactions in the solar nebula.

A phase I study (CA180021-Segment 2) of dasatinib in patients (pts) with advanced solid tumors

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Background: SPRYCEL™ is a potent, orally active, multi-targeted kinase inhibitor, active against BCR-ABL and SRC family kinases. We report the results of a Phase I dose-escalation study evaluating safety, tolerability, pharmacokinetics, and biomarkers of dasatinib in pts with advanced solid tumors. Methods: Pts with adequate hematologic, renal, cardiac and liver function received oral dasatinib once daily for 7 days per week. Three doses and schedules were examined: 90 mg BID; 140 mg QD; and 180 mg QD. Pharmacokinetics and pharmacodynamic biomarkers were collected on Days 1 and 26 of Cycle 1. Tissue biomarkers were assessed at screening. CT was performed at least every 8 weeks, and FDG-PET at weeks 4, and 8. Results: 26 pts [M=15, F=11] ECOG PS ≤ 2 with epithelial tumors (n=14) or other solid tumors (n=12) have been treated in escalating dose levels. Toxicity was generally mild; most patients came off study for progressive disease. DLTs of pleural effusions were seen in 3/9 subjects on the 180 mg cohort, 2 of whom had pre-existing effusions. Patients with pleural effusion have been excluded from future enrollment. The maximum tolerated dose has not been identified. There have been no objective responses on CT. Six patients have had stable disease with continued study treatment for 2–10 months. Conclusions: Dasatinib can be safely administered at doses of 140 and 180 mg QD. Clinical efficacy, pharmacokinetics, and correlative studies of tumor biopsy material and early FDG-PET results will be reported.

No significant financial relationships to disclose.

Rapid accretion and early core formation on asteroids and the terrestrial planets from Hf-W chronometry

The timescales and mechanisms for the formation and chemical differentiation of the planets can be quantified using the radioactive decay of short-lived isotopes. Of these, the (182)Hf-to-(182)W decay is ideally suited for dating core formation in planetary bodies. In an earlier study, the W isotope composition of the Earth's mantle was used to infer that core formation was late (> or = 60 million years after the beginning of the Solar System) and that accretion was a protracted process. The correct interpretation of Hf-W data depends, however, on accurate knowledge of the initial abundance of (182)Hf in the Solar System and the W isotope composition of chondritic meteorites. Here we report Hf-W data for carbonaceous and H chondrite meteorites that lead to timescales of accretion and core formation significantly different from those calculated previously. The revised ages for Vesta, Mars and Earth indicate rapid accretion, and show that the timescale for core formation decreases with decreasing size of the planet. We conclude that core formation in the terrestrial planets and the formation of the Moon must have occurred during the first approximately 30 million years of the life of the Solar System.

[Results of allogenic and autologous bone marrow transplantation in children with acute myeloid leukemia]

We report on our experience of bone marrow transplantation (BMT) in children with acute myeloblastic leukaemia (AML) and high risk of relapse (initial WBC greater than 20 x 10(9)/l, FAB M 5, M 6, M 7). 32 children were grafted between november 1982 and october 1991 at the Children's Hospital of the University of Jena. Two patients underwent an allogenous BMT in relapse and died from progressive disease. In 13 children an allogeneic BMT was performed in first complete remission. One patient relapsed, two patients died from severe acute graft-versus-host disease, and two patients died from encephalopathy and cardiomyopathy. Eight of the 13 patients are living and well 18 months to eight and a half year after BMT. Seventeen patients received an autologous (unpurged) BMT. Four of them relapsed four to seven months after BMT. The disease free survival (DFS) for the 29 patients grafted in remission was 0.65. There was no statistical significant difference in DFS between patients with allogeneic and autologous BMT. We conclude that in children with AML and high risk for relapse BMT offers a real chance for better survival. Autologous BMT avoids the problems of graft-versus-host disease and of finding suitable donors for allogeneic marrow transplantation.

[Therapy of acute myeloid leukemia in children--results of the AML II/87 multicenter study]

Fifty seven patients entered the cooperative study AML II/87 of the working group "Pediatric Hematology and Oncology" of East Germany. Two patients with initial hyperleukocytosis died prior therapy. 13 patients died within the first 4 weeks of therapy, 3 patients did not respond to therapy, and one patient is not yet in remission. 38 patients (70%) attained a complete remission. 15 patients get a bone marrow transplantation in first CR (10 autologous BMT without purging, 5 allogenous BMT). 12 of them are living and well 3 to 34 months after BMT. 9 of the 23 patients under chemotherapy relapsed, one patient is lost to follow up. 13 patients are living in continuous complete remission. The life table probabilities 48 months after the start of the protocol are 0.43 for disease free survival (DFS) and 0.60 for event free interval (EFI). The respective results of the former protocol AML I/82 were 0.34 for DFS and 0.47 for EFI.