High precision elemental abundances for tektites and crater glasses-thorium,uranium and potassium

Thorium, uranium and potassium mean abundances for 15 Ivory Coast tektites, 23 Australites, 10 Philippinites, 25 Thailandites, 16 Bediasites and 12 Moldavites are reported. Abundances are also reported for Muong Nong type tektites, Nordlinger Ries crater glass, Bosumtwi crater glass and Darwin crater glass. Previous measurements are reviewed. The value of the present work lies in the fact that high precision instrumental neutron activation analysis was employed to measure a large number of tektites encompassing the major strewn fields. Four independent measurements of thorium were made for each specimen with two Ge(Li) gamma spectrometers. Two of the measurements were based on the 312 keV gamma of²³³Pa, while the other two measurements were based on the uranium and X-rays which accompany the decay of²³³Pa. Internal consistency among the four thorium measurements is high. The uranium measurements were based on the 106 keV gamma of²³⁹Np, while potassium was measured from the 1524 keV gamma of⁴²K.     

On the monotonicity of the power functions of tests based on traces of multivariate beta matrices

It is shown that for the MANOVA problem the power function of the test based on the trace of a multivariate beta matrix is monotonically increasing in each noncentrality parameter provided that the cutoff point is not too large. This result is also true for the problem of testing independence of two sets of variates.     

Novel synthesis of 19-nor-vitamin D compounds

1,25-Dihydroxy-19-nor-vitamin D₃ was prepared efficiently in a convergent synthesis starting with (−)-quinic acid and a ketone of the Windaus-Grundmann type.     

Untersuchung verschiedener Lebensmittel

Ohne Zusammenfassung     

High-performance liquid chromatographic analyses of the antihypertensive drug captopril

High-performance liquid chromatographic systems have been developed to separate and quantitate captopril. The presence of interfering excipients in various formulations necessitated the development of three assays, each with distinctly different columns and mobile phases. All work well for bulk material, providing short analysis time, high precision, and rapid sample preparation, demonstrating that there is not necessarily one, best, high-performance liquid chromatographic system. The advantages and shortcomings of the ion-exchange, amino and octadecylsilane systems are evaluated and one of them is selected as optimum for bulk and tablet analysis.     

Predicting extinction or explosion in a Galton–Watson branching process

Based on observations $X_1,\dots ,X_n$ X 1 , … , X n of successive generations of a discrete-parameter Galton–Watson branching process, one wishes to predict whether extinction or explosion will ultimately occur. This problem can be formulated as a simple hypothesis-testing problem to which the Neyman–Pearson Lemma is directly applicable if the extinction probability is known or estimable. If it is not, valid (but conservative) tests still can be obtained.     

Identification of oxidative post-translational modification of serum albumin in patients with idiopathic pulmonary arterial hypertension and pulmonary hypertension of sickle cell anemia

Pulmonary hypertension (PH) in sickle cell anemia (SCA) is characterized by decreased nitric oxide bioavailability that might, in part, be related to oxidative stress. Oxidative post-translational modifications of plasma proteins may serve as hallmarks of disease severity and could result in altered protein function and structure. We hypothesized that serum albumin in patients with PH of SCA undergoes oxidative post-translational modification and that this modification may reflect important mediators of disease pathogenesis that are common to both idiopathic pulmonary arterial hypertension (IPAH) and PH of SCA. To explore this hypothesis, we studied albumin purified from the plasma of patients in four subject groups: SCA and PH, SCA steady-state without PH, IPAH, and normal volunteers. Purified albumin was analyzed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) and liquid chromatography/tandem mass spectrometry (LC/MS/MS). Using MALDI-TOFMS, we identified that an ion corresponding to a malondialdehyde (MDA)-modified albumin peptide was differentially present in patients with IPAH and PH of SCA. These results were confirmed by dot-blotting and Western analysis. We localized the site of MDA modification to albumin residue K159 using LC/MS/MS. Thus, we have identified an MDA modification of serum albumin that appears to be a common link between PH of SCA and IPAH. This finding supports the notion that oxidative stress modulates the pathogenesis of PH of SCA and suggests that this and other post-translational modifications may be important biomarkers of disease.     

Evaluation of an on-target sample preparation system for matrix-assisted laser desorption/ionization time-of-flight mass spectrometry in conjunction with normal-flow peptide high-performance liquid chromatography for peptide mass fingerprint analyses

Large-scale mass spectrometry (MS)-based proteomic analyses require high-throughput sample preparation techniques due to the increasing numbers of samples that make up a typical proteomics experiment. Moreover, extensive sample pre-treatment steps are necessary prior to MS acquisition for even the most rapid and robust MS-based proteomics methodology, matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) MS followed by peptide mass fingerprinting (PMF) analysis. These include sample purification and fractionation, removal of digestion buffers or solvents, and spotting of sample with matrix onto the MALDI target. These multiple steps of time-consuming sample handling can result in high overall analysis costs and the likelihood of sample contamination and loss. In order to overcome some of these limitations in sample processing, we have investigated the use of a novel, simple, inexpensive 96-well elastomeric array that affixes to a MALDI target to create an on-target 96-well plate that accommodates a high solution volume (ca. 200 microL), thereby enabling the on-target processing of samples for MALDI-TOFMS. We explored several factors that influence MALDI sample preparation: type of matrix, solution volume, solution organic composition, solution drying rates and matrix/analyte co-crystallization methods. We also investigated the use of the 96-well elastomeric device for coupling MALDI-TOFMS analysis directly to high flow rate (1 mL/min) reversed-phase (rp)-HPLC. By developing an optimized, robust sample preparation protocol, we were able to obtain mass spectra with a high signal-to-noise ratio from peptide standards present at the 50-fmol level in large starting volumes of solution. PMF analyses were possible from 1-pmol and 500-fmol protein-digest standards. Coupling the device to high-flow HPLC (750 microL/min) yielded a robust and semi-automated means to obtain enhanced MALDI-TOFMS data at 500 ng of protein digest. These methodologies developed for this simple, on-target, elastomeric device show promise for streamlining the sample preparation process from HPLC to MALDI-MS.