Enhanced γ-Ray Emission from Neutron Unbound States Populated in ß Decay.

Total absorption spectroscopy is used to investigate the ß-decay intensity to states above the neutron separation energy followed by γ-ray emission in (87,88)Br and (94)Rb. Accurate results are obtained thanks to a careful control of systematic errors. An unexpectedly large γ intensity is observed in all three cases extending well beyond the excitation energy region where neutron penetration is hindered by low neutron energy. The γ branching as a function of excitation energy is compared to Hauser-Feshbach model calculations. For (87)Br and (88)Br the γ branching reaches 57% and 20%, respectively, and could be explained as a nuclear structure effect. Some of the states populated in the daughter can only decay through the emission of a large orbital angular momentum neutron with a strongly reduced barrier penetrability. In the case of neutron-rich (94)Rb the observed 4.5% branching is much larger than the calculations performed with standard nuclear statistical model parameters, even after proper correction for fluctuation effects on individual transition widths. The difference can be reconciled by introducing an enhancement of 1 order of magnitude in the photon strength to neutron strength ratio. An increase in the photon strength function of such magnitude for very neutron-rich nuclei, if it proves to be correct, leads to a similar increase in the (n,γ) cross section that would have an impact on r process abundance calculations.

Total Absorption Spectroscopy Study of (92)Rb Decay: A Major Contributor to Reactor Antineutrino Spectrum Shape.

The antineutrino spectra measured in recent experiments at reactors are inconsistent with calculations based on the conversion of integral beta spectra recorded at the ILL reactor. (92)Rb makes the dominant contribution to the reactor antineutrino spectrum in the 5-8 MeV range but its decay properties are in question. We have studied (92)Rb decay with total absorption spectroscopy. Previously unobserved beta feeding was seen in the 4.5-5.5 region and the GS to GS feeding was found to be 87.5(25)%. The impact on the reactor antineutrino spectra calculated with the summation method is shown and discussed.

Expressed sequence tags and proteomics of antennae from the tortricid moth, Epiphyas postvittana.

Genomic and proteomic analyses of the antennae of the light brown apple moth, Epiphyas postvittana (Walker) (Lepidoptera: Tortricidae) were undertaken to identify genes and proteins potentially involved in odorant and pheromone binding and turnover. An EST approach yielded 5739 sequences, comprising 808 contigs and 1545 singletons. InterPro and Blast analyses revealed members of families implicated in odorant and pheromone binding (PBPs, GOBPs, ABPXs and CSPs) and turnover (CXEs, GSTs, CYPs). Of the three pheromone binding proteins (PBPs) identified, two were more highly expressed at the RNA and protein levels in adult male antennae (EpPBP1, EpPBP3), while a third was more highly expressed in female antennae (EpPBP2). To identify proteins involved in the detection of sex-specific signals, differential 2D gel electrophoresis (pH 5-8) followed by mass spectrometry was conducted on antennal proteins from males versus females. Identified male-biased proteins included a pheromone binding protein, a porin, a short chain dehydrogenase/reductase, and a member of the takeout family.

Human astrocytic grid networks patterned in parylene-C inlayed SiO2 trenches.

Recent literature suggests that glia, and in particular astrocytes, should be studied as organised networks which communicate through gap junctions. Astrocytes, however, adhere to most surfaces and are highly mobile cells. In order to study, such organised networks effectively in vitro it is necessary to influence them to pattern to certain substrates whilst being repelled from others and to immobilise the astrocytes sufficiently such that they do not continue to migrate further whilst under study. In this article, we demonstrate for the first time how it is possible to facilitate the study of organised patterned human astrocytic networks using hNT astrocytes in a SiO2 trench grid network that is inlayed with the biocompatible material, parylene-C. We demonstrate how the immobilisation of astrocytes lies in the depth of the SiO2 trench, determining an optimum trench depth and that the optimum patterning of astrocytes is a consequence of the parylene-C inlay and the grid node spacing. We demonstrate high fidelity of the astrocytic networks and demonstrate that functionality of the hNT astrocytes through ATP evoked calcium signalling is also dependent on the grid node spacing. Finally, we demonstrate that the location of the nuclei on the grid nodes is also a function of the grid node spacing. The significance of this work, is to describe a suitable platform to facilitate the study of hNT astrocytes from the single cell level to the network level to improve knowledge and understanding of how communication links to spatial organisation at these higher order scales and trigger in vitro research further in this area with clinical applications in the area of epilepsy, stroke and focal cerebral ischemia.

Refined crystal structure of the phosphorylase-heptulose 2-phosphate-oligosaccharide-AMP complex.

The crystal structure of phosphorylase b-heptulose 2-phosphate complex with oligosaccharide and AMP bound has been refined by molecular dynamics and crystallographic least-squares with the program XPLOR. Shifts in atomic positions of up to 4 A from the native enzyme structure were correctly determined by the program without manual intervention. The final crystallographic R value for data between 8 and 2.86 A resolution is 0.201, and the overall root-mean-square difference between the native and complexed structure is 0.58 A for all protein atoms. The results confirm the previous observation that there is a direct hydrogen bond between the phosphate of heptulose 2-phosphate and the pyridoxal phosphate 5'-phosphate group. The close proximity of the two phosphates is stabilized by an arginine residue, Arg569, which shifts from a site buried in the protein to a position where it can make contact with the product phosphate. There is a mutual interchange in position between the arginine and an acidic group, Asp283. These movements represent the first stage of the allosteric response which converts the catalytic site from a low to a high-affinity binding site. Communication of these changes to other sites is prevented in the crystal by the lattice forces, which also form the subunit interface. The constellation of groups in the phosphorylase transition state analogue complex provides a structural basis for understanding the catalytic mechanism in which the cofactor pyridoxal phosphate 5'-phosphate group functions as a general acid to promote attack by the substrate phosphate on the glycosidic bond when the reaction proceeds in the direction of glycogen degradation. In the direction of glycogen synthesis, stereoelectronic effects contribute to the cleavage of the C-1-O-1 bond. In both reactions the substrate phosphate plays a key role in transition state stabilization. The details of the oligosaccharide, maltoheptaose, interactions with the enzyme at the glycogen storage site are also described.

Audibility of the fourth heart sound. Relationship to presence of disease and examiner experience.

To determine the meaning of an audible fourth heart sound (S4), 51 subjects (21 normal and 30 abnormal persons), aged between 38 and 74 years (mean, 55.4 years), were examined by nine "blinded" physicians (four cardiologists, five house staff officers). Audibility scores were compared with phonocardiographic, echocardiographic, and hemodynamic measurements. An S4 was recorded graphically in 35 (68.6%) of all 51 subjects and splitting of the first sound (S1), in 37 subjects (72.5%). The abnormal group did not differ significantly from the normal subjects in incidence of recordable S4 or splitting of S1. Audibility of S4, however, correlated with its recorded amplitude, size, and palpability of the presystolic apical impulse, left ventricular systolic and diastolic diameters, and history of myocardial infarction. Despite variation among examiners, house staff officers were likelier than cardiologists to believe an S4 present even in cases lacking a recordable S4 and in normal subjects and were more apt to believe an S4 present when splitting of S1 was identified graphically. We conclude that an audible S4 continues to provide evidence for cardiac disease, and that increasing examiner experience renders this finding fairly specific. Less experienced examiners are likelier to confuse splitting of S1 with the S4, suggesting that training should be focused on means to improve this differentiation.

Histologic evidence of distal coronary thromboembolism. A complication of acute proximal coronary artery thrombolysis therapy.

Distal migration of occluding coronary thrombus during thrombolysis therapy for acute myocardial infarction rarely has been observed angiographically. Necropsy documentation of the final location of embolic fragments in this circumstance has not been reported previously. This report documents multiple occluded intramyocardial vessels with thrombus observed to have showered distally during thrombolysis therapy. Depending on size and number, fragments of dislodging proximal coronary embolus may produce additional myocardial necrosis.

Clinical and radiographic findings of a sliding inguinoscrotal hernia containing the urinary bladder.

Large sliding inguinal hernias involving the urinary bladder are rare. We present the relevant clinical data, radiographic images, and the intraoperative findings of a sliding inguinoscrotal herniation of the urinary bladder. A 67-year-old male presented with a scrotal mass and the need to manually compress his scrotum in order to void. Diagnosed with a large sliding inguinal hernia with significant bladder involvement (scrotal cystocele), the patient underwent an inguinal herniorraphy and replacement of the bladder in the retroperitoneal space. Surgery proved to be successful in the management of the inguinal hernia and voiding dysfunction.