A nucleosynthetic origin for the Earth's anomalous (142)Nd composition.

A long-standing paradigm assumes that the chemical and isotopic compositions of many elements in the bulk silicate Earth are the same as in chondrites. However, the accessible Earth has a greater (142)Nd/(144)Nd ratio than do chondrites. Because (142)Nd is the decay product of the now-extinct (146)Sm (which has a half-life of 103 million years), this (142)Nd difference seems to require a higher-than-chondritic Sm/Nd ratio for the accessible Earth. This must have been acquired during global silicate differentiation within the first 30 million years of Solar System formation and implies the formation of a complementary (142)Nd-depleted reservoir that either is hidden in the deep Earth, or lost to space by impact erosion. Whether this complementary reservoir existed, and whether or not it has been lost from Earth, is a matter of debate, and has implications for determining the bulk composition of Earth, its heat content and structure, as well as for constraining the modes and timescales of its geodynamical evolution. Here we show that, compared with chondrites, Earth's precursor bodies were enriched in neodymium that was produced by the slow neutron capture process (s-process) of nucleosynthesis. This s-process excess leads to higher (142)Nd/(144)Nd ratios; after correction for this effect, the (142)Nd/(144)Nd ratios of chondrites and the accessible Earth are indistinguishable within five parts per million. The (142)Nd offset between the accessible silicate Earth and chondrites therefore reflects a higher proportion of s-process neodymium in the Earth, and not early differentiation processes. As such, our results obviate the need for hidden-reservoir or super-chondritic Earth models and imply a chondritic Sm/Nd ratio for the bulk Earth. Although chondrites formed at greater heliocentric distances and contain a different mix of presolar components than Earth, they nevertheless are suitable proxies for Earth's bulk chemical composition.

Late formation and prolonged differentiation of the Moon inferred from W isotopes in lunar metals.

The Moon is thought to have formed from debris ejected by a giant impact with the early 'proto'-Earth and, as a result of the high energies involved, the Moon would have melted to form a magma ocean. The timescales for formation and solidification of the Moon can be quantified by using 182Hf-182W and 146Sm-142Nd chronometry, but these methods have yielded contradicting results. In earlier studies, 182W anomalies in lunar rocks were attributed to decay of 182Hf within the lunar mantle and were used to infer that the Moon solidified within the first approximately 60 million years of the Solar System. However, the dominant 182W component in most lunar rocks reflects cosmogenic production mainly by neutron capture of 181Ta during cosmic-ray exposure of the lunar surface, compromising a reliable interpretation in terms of 182Hf-182W chronometry. Here we present tungsten isotope data for lunar metals that do not contain any measurable Ta-derived 182W. All metals have identical 182W/184W ratios, indicating that the lunar magma ocean did not crystallize within the first approximately 60 Myr of the Solar System, which is no longer inconsistent with Sm-Nd chronometry. Our new data reveal that the lunar and terrestrial mantles have identical 182W/184W. This, in conjunction with 147Sm-143Nd ages for the oldest lunar rocks, constrains the age of the Moon and Earth to Myr after formation of the Solar System. The identical 182W/184W ratios of the lunar and terrestrial mantles require either that the Moon is derived mainly from terrestrial material or that tungsten isotopes in the Moon and Earth's mantle equilibrated in the aftermath of the giant impact, as has been proposed to account for identical oxygen isotope compositions of the Earth and Moon.

A long-lived magma ocean on a young Moon.

A giant impact onto Earth led to the formation of the Moon, resulted in a lunar magma ocean (LMO), and initiated the last event of core segregation on Earth. However, the timing and temporal link of these events remain uncertain. Here, we demonstrate that the low thermal conductivity of the lunar crust combined with heat extraction by partial melting of deep cumulates undergoing convection results in an LMO solidification time scale of 150 to 200 million years. Combining this result with a crystallization model of the LMO and with the ages and isotopic compositions of lunar samples indicates that the Moon formed 4.425 ± 0.025 billion years ago. This age is in remarkable agreement with the U-Pb age of Earth, demonstrating that the U-Pb age dates the final segregation of Earth's core.

Biosynthesis of chondroitin sulfate side chains and hyaluronate. Time-course studies with cartilage slices of calf ribs under different conditions.

The time course of double labeling with 35SO24- and [3H]glucosamine was followed in a semi-in vitro system of cartilage slices from calf ribs whose chondroitin sulfate peptide pool consists of (A) less than 1% of very short under sulfated side chains of less than 10 disaccharide units length, (B) 3--5% of short under sulfated longer side chains (16 to 25 disaccharide units), (C) 3--5% of short, slightly oversulfated side chains (16--23 dissacharide units, very probably containing some dermatan sulfate), (D) the bulk material (74--82% of total uronate) of longest, slightly undersulfated or equally sulfated side chains (22--42 disaccharide units). After 10 min incubation rapid chain elongation with [3H]glucosamine and prelabeling with 35SO24- of endogenous acceptors are apparent. Chains of type A exhibit highest specific radioactivities. During 30--60 min incubation it is mainly chains of type B that show highest specific radioactivities, after 90 min chains of type C. On the after hand, chains of type D always incorporated the highest total amount of both precursors. Preincubation of slices for 40 min at 37 degres C strongly enhances labeling rates of all types A and B. After 10 min preincubation followed by 35SO24- labeling for 60 min, a decrease of radioactivity of type A and a distinct increase with type B are observed during the post incubation period. After pulse chase experiments type B exhibits highest specific radioactivities. The data make it evident that undersulfated short chondroitin sulfate side chains form very rapidly in a well organised manner and grow, by elongation and proceeding sulfation processes, to longer higher sulfated chains. The labeling of the hyaluronate pool is about half of that of the chondroitin sulfate pool after a lag phase of 10 min. The latter increases linearly after 35--45 min incubation time. However, after preincubation and chase experiments the hyaluronate pool is more highly labeled. The data indicate different precursor pools of both biosynthesis mechanisms, probably located in different cell compartments and/or different cartilage cells.

Structural implications for the role of the N terminus in the 'superactivation' of collagenases. A crystallographic study.

For the collagenases PMNL-CL and FIB-CL, the presence of the N-terminal Phe79 correlates with an increase in proteolytic activity. We have determined the X-ray crystal structure of the recombinant Phe79-Gly242 catalytic domain of human neutrophil collagenase (PMNL-CL, MMP-8) using the recently solved model of the Met80-Gly242 form for phasing and subsequently refined it to a final crystallographic R-factor of 18.0% at 2.5 A resolution. The PMNL-CL catalytic domain is a spherical molecule with a flat active site cleft separating a smaller C-terminal subdomain from a bigger N-terminal domain, that harbours two zinc ions, namely a 'structural' and a 'catalytic' zinc, and two calcium ions. The N-terminal segment prior to Pro86, which is disordered in the Met80-Gly242 form, packs against a concave hydrophobic surface made by the C-terminal helix. The N-terminal Phe79 ammonium group makes a salt link with the side chain carboxylate group of the strictly conserved Asp232. Stabilization of the catalytic site might be conferred via strong hydrogen bonds made by the adjacent, likewise strictly conserved Asp233 with the characteristic 'Met-turn', which forms the base of the active site residues.

Disorganization of glycolytic and gluconeogenic pathways in skeletal muscle of aged persons studied by histometric and enzymatic methods.

Histometric data obtained by the point counting method, and the enzyme patterns of glycolysis, gluconeogenesis, fatty degradation and energy transfer have been determined in the same muscle specimens of m. vastus lateralis from 12 untrained patients between the ages of 4 and 78 years who suffered no disturbance of the neuromuscular system. Activities of 18 enzymes have been related to pure muscle weight corrected for fatty and connective tissue content, as well as to single fibre weight. A comparable muscle enzyme pattern was found in persons of around 20 years old and around 70 years old when expressed per gram of single fibre weight. However, in terms of grams of pure muscle weight, a significant activity decrease with age was obtained for 6-phosphofructokinase, triosephosphate dehydrogenase and phosphoenolpyruvate carboxykinase, whereas activity of hexose diphosphatase increased with age as also did 3-hydroxyacyl-CoA dehydrogenase activity. Five other cytoplasmic enzyme activities involved in glycolysis and energy transfer did not change significantly with age, nor did lysosomal acid phosphatase. The mitochondrial enzyme activities of gluconeogenesis (for example, pyruvate carboxylase, malic enzyme) were diminished to a lesser extent as also the auxiliary enzymes glutamic-oxaloacetic transminase and glutamic-pyruvic transaminase; glutamate dehydrogenase activity remained unchanged. The findings indicate a distinct disorganization of cytoplasmic glycolysis and gluconeogenesis pathways in presenile human skeletal muscle, confirming the histometric data already described. They cannot be explained by changes with age in numerical or areal ratio of type I and type II fibres.

Inhibitory and stimulating effects of various types and series of prostaglandins on in vitro biosynthesis of proteochondroitin-4,6-sulfate and protein and anaerobic glycolysis in calf rib cartilage.

The effect of various types of prostaglandins (PGs) have been studied in a semi-in-vitro system with cartilage slices of calf ribs. 0.1 mmol/1 PG B1, D2, E1, E2, F1 alpha, F2 alpha inhibit biosynthesis of Ch-4,6-S protein to a higher extent than 10 mumol/l; 1 and 2 series PG E and F (but not B) inhibit similarly, PG A2 inhibits twice as much. With biosynthesis of total protein 2-series PG A, B, E, F act more inhibitorily than 1-series PG. 10 mumol/l PG A2, E1, E2 produce cAMP-like effects, e.g. acceleration of biosynthesis of Ch-4,6-S protein and total protein as well as of anaerobic glycolysis; PG F2 alpha stimulates the first two anabolic processes, PG B1 only the second one. PG A1 stimulates Ch-4,6-S protein biosynthesis and anaerobic glycolysis, a cGMP-like effect. 20 mumol/l diBu-cAMP or cAMP (together with 0.1 mmol/l theophylline) produce stimulating and inhibitory effects on these three anabolic processes; both compounds produce additively positive or additively negative effects in connection with the inhibitory PG effects on these three anabolic processes.

Protracted core formation and rapid accretion of protoplanets.

Understanding core formation in meteorite parent bodies is critical for constraining the fundamental processes of protoplanet accretion and differentiation within the solar protoplanetary disk. We report variations of 5 to 20 parts per million in (182)W, resulting from the decay of now-extinct (182)Hf, among five magmatic iron meteorite groups. These (182)W variations indicate that core formation occurred over an interval of ~1 million years and may have involved an early segregation of Fe-FeS and a later segregation of Fe melts. Despite this protracted interval of core formation, the iron meteorite parent bodies probably accreted concurrently ~0.1 to 0.3 million years after the formation of Ca-Al-rich inclusions. Variations in volatile contents among these bodies, therefore, did not result from accretion at different times from an incompletely condensed solar nebula but must reflect local processes within the nebula.

[Initial education for parents of children with diabetes: effort and outcomes in children and parents]. / Initialschulung für Eltern von Kindern mit Diabetes: Aufwand und Effekte bei Kindern und Eltern.

INTRODUCTION: Parents are responsible for the therapy and prognosis of their child with diabetes. Thus a structured initial education covering medical and psychosocial aspects of diabetes for parents offered by a multidisciplinary paediatric diabetes team is essential. METHODS: Quality of educational process and outcomes were assessed in 10 German paediatric diabetes units with parents of 81 children (4-14 yrs). A structured diabetes education programme for parents was used. Outcome parameters were parental satisfaction with education, diabetes knowledge (DWT: Typ1), children's quality of metabolic control and health related quality of life (QoL) (KINDL-R) and both parents' well-being (WHO-5) at onset (t0) and 6 (t1) and 12 (t2) months later. RESULTS: On average 30.6 ± 10.1 lessons were required. Parents were highly satisfied with the education. Their diabetes knowledge at t0 and t1 exceeded the T-norms of the best educated adult patients. Children's QoL at t1 and t2, assessed by their parents, didn't differ from representative healthy norms. Mean HbA1c at t1 was 6.8 ± 1.0% and 7.2 ± 1.2% at t2. Compared to standard values of WHO-5 mothers' psychological well-being was poor. Scores < 13 (indicating depression) were seen at 50% (t0), 41% (t1) and 29% (t2) of the mothers. DISCUSSION: The comprehensive diabetes education leads to high levels of diabetes knowledge and satisfaction with care. 12 months after diabetes onset the target of metabolic control (HbA1c < 7.5%) was met by 71% of the children, while their QoL was good. However, the great psychological burden of mothers at onset indicates their need for ongoing specialized care.