Comparison of Human Surrogate Responses in Underbody Blast Loading Conditions.

Impact biomechanics research in occupant safety predominantly focuses on the effects of loads applied to human subjects during automotive collisions. Characterization of the biomechanical response under such loading conditions is an active and important area of investigation. However, critical knowledge gaps remain in our understanding of human biomechanical response and injury tolerance under vertically accelerated loading conditions experienced due to underbody blast (UBB) events. This knowledge gap is reflected in anthropomorphic test devices (ATDs) used to assess occupant safety. Experiments are needed to characterize biomechanical response under UBB relevant loading conditions. Matched pair experiments in which an existing ATD is evaluated in the same conditions as a post mortem human subject (PMHS) may be utilized to evaluate biofidelity and injury prediction capabilities, as well as ATD durability, under vertical loading. To characterize whole body response in the vertical direction, six whole body PMHS tests were completed under two vertical loading conditions. A series of 50th percentile hybrid III ATD tests were completed under the same conditions. Ability of the hybrid III to represent the PMHS response was evaluated using a standard evaluation metric. Tibial accelerations were comparable in both response shape and magnitude, while other sensor locations had large variations in response. Posttest inspection of the hybrid III revealed damage to the pelvis foam and skin, which resulted in large variations in pelvis response. This work provides an initial characterization of the response of the seated hybrid III ATD and PMHS under high rate vertical accelerative loading.

Aeromagnetic and radio echo ice-sounding measurements show much greater area of the dufek intrusion, antarctica.

A combined aeromagnetic and radio echo ice-sounding survey made in 1978 in Antarctica over the Dufek layered mafic intrusion suggests a minimum area of the intrusion of about 50,000 square kilometers, making it comparable in size with the Bushveld Complex of Africa. Comparisons of the magnetic and subglacial topographic profiles illustrate the usefulness of this combination of methods in studying bedrock geology beneath ice-covered areas. Magnetic anomalies range in peak-to-through amplitude from about 50 nanoteslas over the lowermost exposed portion of the section in the Dufek Massif to about 3600 nanoteslas over the uppermost part of the section in the Forrestal Range. Theoretical magnetic anomalies, computed from a model based on the subice topography fitted to the highest amplitude observed magnetic anomalies, required normal and reversed magnetizations ranging from 10(-3) to 10(-2) electromagnetic units per cubic centimeter. This result is interpreted as indicating that the Dufek intrusion cooled through the Curie isotherm during one or more reversals of the earth's magnetic field.

Structure of the catalytic domain of fibroblast collagenase complexed with an inhibitor.

Collagenase is a zinc-dependent endoproteinase and is a member of the matrix metalloproteinase (MMP) family of enzymes. The MMPs participate in connective tissue remodeling events and aberrant regulation has been associated with several pathologies. The 2.4 angstrom resolution structure of the inhibited enzyme revealed that, in addition to the catalytic zinc, there is a second zinc ion and a calcium ion which play a major role in stabilizing the tertiary structure of collagenase. Despite scant sequence homology, collagenase shares structural homology with two other endoproteinases, bacterial thermolysin and crayfish astacin. The detailed description of protein-inhibitor interactions present in the structure will aid in the design of compounds that selectively inhibit individual members of the MMP family. Such inhibitors will be useful in examining the function of MMPs in pathological processes.

In depth analysis of kinase cross screening data to identify chemical starting points for inhibition of the Nek family of kinases.

Potent, selective, and cell active small molecule kinase inhibitors are useful tools to help unravel the complexities of kinase signaling. As the biological functions of individual kinases become better understood, they can become targets of drug discovery efforts. The small molecules used to shed light on function can also then serve as chemical starting points in these drug discovery efforts. The Nek family of kinases has received very little attention, as judged by number of citations in PubMed, yet they appear to play many key roles and have been implicated in disease. Here we present our work to identify high quality chemical starting points that have emerged due to the increased incidence of broad kinome screening. We anticipate that this analysis will allow the community to progress towards the generation of chemical probes and eventually drugs that target members of the Nek family.

OCO-2 advances photosynthesis observation from space via solar-induced chlorophyll fluorescence.

Quantifying gross primary production (GPP) remains a major challenge in global carbon cycle research. Spaceborne monitoring of solar-induced chlorophyll fluorescence (SIF), an integrative photosynthetic signal of molecular origin, can assist in terrestrial GPP monitoring. However, the extent to which SIF tracks spatiotemporal variations in GPP remains unresolved. Orbiting Carbon Observatory-2 (OCO-2)'s SIF data acquisition and fine spatial resolution permit direct validation against ground and airborne observations. Empirical orthogonal function analysis shows consistent spatiotemporal correspondence between OCO-2 SIF and GPP globally. A linear SIF-GPP relationship is also obtained at eddy-flux sites covering diverse biomes, setting the stage for future investigations of the robustness of such a relationship across more biomes. Our findings support the central importance of high-quality satellite SIF for studying terrestrial carbon cycle dynamics.

Matrix metalloproteinase inhibitors containing a (carboxyalkyl)amino zinc ligand: modification of the P1 and P2' residues.

Systematic modification of the presumed P1 side chain in a series of (carboxyalkyl)amino-based inhibitors of matrix metalloproteinases enabled identification of the 2-(1,3-dihydro-1,3-dioxo-2H-benz[f]isoindol-2-yl)ethyl group as a preferred substituent imparting potent inhibition of the enzymes collagenase and gelatinase. It was subsequently found that the P2'-P3' residues in this series could be replaced by small non-peptide residues, while maintaining inhibitory potency. The imide group in this series of compounds can undergo autocatalytic hydrolysis under neutral conditions.

Low-molecular-weight solutes released during mild acid hydrolysis of the lipopolysaccharide of Pseudomonas aeruginosa.

A careful examination of the low-molecular-weight solutes released during mild acid hydrolysis of the lipopolysaccharide of Pseudomonas aeruginosa (N.C.T.C. 1999) revealed the presence of ethanolamine triphosphate. During storage, the compound decomposed to give ethanolamine pyrophosphate, identified in a previous study (Drewry et al., 1971); PP(i) may be a further decomposition product. Evidence for the attachment of ethanolamine triphosphate to a polysaccharide fraction was obtained, but the possibility that some was attached to the lipid A moiety was not excluded. Basic compounds released during the hydrolysis of lipopolysaccharide included amino acids, polyamines and oligopeptides.

Solid-supported reagents in organic synthesis.

The current interest in solid-phase organic synthesis has led to a renewed interest in a complementary technique in which solid supported reagents are used in solution phase chemistry. This technique obviates the need for attachment of the substrate to a solid-support, and enables the chemist to monitor the reactions using familiar analytical techniques. The purpose of this review is to increase awareness of the wide range of useful transformations which can be accomplished using solid-supported reagents.

Studies of polysaccharide fractions from the lipopolysaccharide of Pseudomonas aeruginosa N.C.T.C. 1999.

Two polymeric water-soluble fractions were isolated by gel filtration after mild acid hydrolysis of the lipopolysaccharide from Pseudomonas aeruginosa N.C.T.C. 1999. The fraction of higher molecular weight retained the O-antigenic specificity of the lipopolysaccharide and may be 'side-chain' material. This fraction was rich in N (about 10%) and gave several basic amino compounds on acid hydrolysis; fucosamine (at least 2.8% w/w) was the only specifc component identified. The fraction of lower molecular weight was a phosphorylated polysaccharide apparently corresponding to 'core' material. The major components of this fraction and their approximate molar proportions were: glucose (3-4); rhamnose (1); heptose (2); 3-deoxy-2-octulonic acid (1); galactosamine (1); alanine (1-1.5); phosphorus (6-7). In the intact lipopolysaccharide this fraction was probably linked to lipid A via a second residue of 3-deoxy-2-octulonic acid, and probably also contained additional phosphate residues and ethanolamine. The residues of 3-deoxy-2-octulonic acid were apparently substituted in the C-4 or C-5 position, and the phosphorylated heptose residues in the C-3 position. The rhamnose was mainly 2-substituted, though a little 3-substitution was detected. The glucose residues were either unsubstituted or 6-substituted. Four neutral oligosaccharides were produced by partial acid hydrolysis and were characterized by chemical, enzymic, chromatographic and mass-spectrometric methods of analysis. The structures assigned were: Glcpalpha1-6Glc; Glcpbeta1-2Rha; Rhapalpha1-6Glc; Glcpbeta1-2Rhapalpha1-6Glc. The galactosamine was substituted in the C-3 or C-4 position, the attachment of alanine was indicated, and evidence that the amino sugar linked the glucose-rhamnose region to the 'inner core' was obtained.

Staphylococcal slime: a cautionary tale.

Slime production by Staphylococcus epidermidis may be important in the adherence to and colonization of biomedical devices, and slime has been proposed to have various effects on the immune system. Attempts were made to isolate, purify, and chemically characterize slime from S. epidermidis cultivated under fluid on tryptic soy broth-agar medium. "Crude slime" from slime-producing strain RP-12 was characterized by a high galactose content. Similar materials in similar yields were isolated from slime-producing strain Kaplan, a non-slime-producing mutant, Kaplan-6A, and sterile medium controls, suggesting that crude slime was derived mainly from the medium. The occurrence of D- and L-galactose and pyruvate and sulfate residues and methylation analysis of these crude slime preparations, monitored by gas-liquid chromatography and mass spectrometry, showed that the agar was the main source of crude slime, suggesting that the preparation was largely an artifact of the growth and isolation procedures. Similar high-galactose-content preparations from both S. epidermidis and Staphylococcus aureus, assumed to be bacterial products and with a variety of biological activities, have been described by other investigators. Growth attached to a solid surface appears to be important for slime production. An accumulation of turned-over cell surface molecules and released macromolecules such as DNA may contribute to slime production. Avoidance of agar and development of a chemically defined medium for slime production are recommended for further studies.

Studies of lipid A fractions from the lipopolysaccharides of Pseudomonas aeruginosa and Pseudomonas alcaligenes.

Lipid A fractions from Pseudomonas aeruginosa and Pseudomonas alcaligenes have similar compositions and structural features. By means of hydrazinolysis of the parent lipopolysaccharides and partial hydrolysis of the deacylation products, it was established that both lipids are derived from the beta-(1-->6)-linked disaccharide of glucosamine. Phosphorylated derivatives of the disaccharide from Ps. aeruginosa were also characterized. The lipids differ mainly in the absence of hexadecanoic acid and 2-hydroxydodecanoic acid from the lipid from Ps. alcaligenes. Evidence that in Ps. aeruginosa these acids are ester-linked to residues of 3-hydroxyalkanoic acids (including 3-hydroxydecanoic acid) was obtained. Heterogeneity of lipid A fractions was indicated by t.l.c., and by gel filtration of de-O-acylation products from mild alkaline methanolysis of the lipids.

Inhibition of thermolysin by phosphonamidate transition-state analogues: measurement of 31P-15N bond lengths and chemical shifts in two enzyme-inhibitor complexes by solid-state nuclear magnetic resonance.

31P and 15N chemical shifts and 31P-15N bond lengths have been measured with solid-state NMR techniques in two inhibitors of thermolysin, carbobenzoxy-Glyp-L-Leu-L-Ala (ZGpLA) and carbobenzoxy-L-Phep-L-Leu-L-Ala (ZFpLA), both as free lithium salts and when bound to the enzyme. Binding of both inhibitors to thermolysin results in large changes in the 31P chemical shifts. These changes are more dramatic for the tighter binding inhibitor ZFpLA, where a approximately 20 ppm downfield movement of the 31P isotropic chemical shift (sigma iso) is observed. This shift is due to changes in the shift tensor elements sigma 11 and sigma 22, while sigma 33 remains essentially constant. We observed a similar pattern for ZGpLA, but only a approximately 5 ppm change occurs in sigma iso. The changes in the 15N chemical shifts for both inhibitors are small upon binding, amounting to downfield shifts of 2 and 4 ppm for ZGpLA and ZFpLA, respectively. This indicates that there are no changes in the protonation state of the 15N in either the ZFpLA- or the ZGpLA-thermolysin complex. NMR distance measurements yield a P-N bond length rP-N = 1.68 +/- 0.03 A for the tight binding inhibitor ZFpLA both in its free lithium salt form and in its thermolysin-ZFpLA complex, a distance that is much shorter than the 1.90-A distance reported by X-ray crystallography studies [Holden et al. (1987) Biochemistry 26, 8542-8553].(ABSTRACT TRUNCATED AT 250 WORDS)

2-Amino-4,6-diarylpyridines as novel ligands for the estrogen receptor.

We have prepared a novel series of 2-amino-4,6-diarylpyridines that function as ligands of estrogen receptor alpha (ERalpha) and estrogen receptor beta (ERbeta). These compounds bind to both ERalpha and ERbeta with a modest selectivity for the alpha subtype. The most potent of these analogues, compound 19, has a K(i)=20nM at ERalpha. These molecules represent a novel template for designing potentially useful ligands for the estrogen receptor.