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A multifunctional macromolecular thiol (TPVA) obtained by esterification of poly(vinyl alcohol) (PVA) with 3-mercaptopropionic acid was characterized by a combination of NMR, IR, transmission electron microscopy (TEM), and differential scanning calorimetry (DSC), and was used as a wheat gluten (WG) reactive modifier. The effect of TPVA molecular weight (M(w) = 2000, 9500, 50 000, and 205 000) and blend composition (5, 20, and 40% w/w TPVA/WG) on the mechanical properties of compression-molded bars indicates that TPVA/WG blends increase the fracture strength by up to 76%, the elongation by 80%, and the modulus by 25% above WG. In contrast, typical WG additives such as glycerol and sorbitol improve flexibility but decrease modulus and strength. Preliminary investigations of suspension rheology, water uptake, molecular weight distribution and electron microscopy of TPVA/WG and PVA/WG blends illustrate the different protein interactions with PVA and TPVA. Further work is underway to determine whether TPVA and WG form protein conjugates or microphase-separated morphologies.

Electromagnetic (and adiabatic) energy losses of pi's and mu's modify the flavor ratio (measured at Earth) of neutrinos produced by pi decay in astrophysical sources, Phi v: phi v mu: phi v tau, from 1:1:1 at low energy to 1:1.8:1.8 at high energy. The transition occurs over 1-2 decades of v energy, and is correlated with a modification of the neutrino spectrum. For gamma-ray bursts, e.g., the transition is expected at approximately 100 TeV and may be detected by km-scale v telescopes. Measurements of the transition energy and energy width will provide unique probes of the physics of the sources. Pi and mu energy losses also affect the ratio of ve flux to total v flux, which may be measured at the resonance (6.3 PeV): It is modified from 1/6(1/15) at low energy to 1/9 (practically 0) at high energy for neutrinos produced in p p (p gamma) interactions.

We analytically study diffusive particle acceleration in relativistic, collisionless shocks. We find a simple relation between the spectral index s and the anisotropy of the momentum distribution along the shock front. Based on this relation, we obtain s=(3beta(u)-2beta(u)beta(2)(d)+beta(3)(d))/(beta(u)-beta(d)) for isotropic diffusion, where beta(u) (beta(d)) is the upstream (downstream) fluid velocity normalized to the speed of light. This result is in agreement with previous numerical determinations of s for all (beta(u),beta(d)), and yields s=38/9 in the ultrarelativistic limit. The spectrum-anisotropy connection is useful for testing numerical studies and constraining anisotropic diffusion results. It suggests that the spectrum is highly sensitive to the form of the diffusion function for particles traveling along the shock front.

A fraction of core-collapse supernovae of type Ib/c are associated with gamma-ray bursts, which are thought to produce highly relativistic jets. Recently, it has been hypothesized that a larger fraction of core-collapse supernovae produce slower jets, which may contribute to the disruption and ejection of the supernova envelope, and explain the unusually energetic hypernovae. We explore the TeV neutrino signatures expected from such slower jets, and calculate the expected detection rates with upcoming Gigaton Cherenkov experiments. We conclude that individual jetted supernovae may be detectable from nearby galaxies.

The high energy neutrino signature from proton-proton and photo-meson interactions in a supernova remnant shell ejected prior to a gamma-ray burst provides a test for the precursor supernova, or supranova, model of gamma-ray bursts. Protons in the supernova remnant shell and photons entrapped from a supernova explosion or a pulsar wind from a fast-rotating neutron star remnant provide ample targets for protons escaping the internal shocks of the gamma-ray burst to interact and produce high energy neutrinos. We calculate the expected neutrino fluxes, which can be detected by current and future experiments.

Core collapse of massive stars resulting in a relativistic fireball jet which breaks through the stellar envelope is a widely discussed scenario for gamma-ray burst production. For very extended or slow rotating stars, the jet may be unable to break through the envelope. Both penetrating and choked jets will produce, by photomeson interactions of accelerated protons, a burst of greater, greater than or similar to 5 TeV neutrinos while propagating in the envelope. The predicted flux, from both penetrating and choked jets, should be easily detectable by planned 1 km(3) neutrino telescopes.

The jets associated with galactic microquasars are believed to be ejected by accreting stellar mass black holes or neutron stars. We show that if the energy content of the jets in the transient sources is dominated by electron-proton plasma, then a several hour outburst of 1-100 TeV neutrinos produced by photomeson interactions should precede the radio flares associated with major ejection events. Several neutrinos may be detected during a single outburst by a 1 km(2) detector, thereby providing a powerful probe of microquasar jet physics.

We show that as a Type II supernova shock breaks out of its progenitor star, it becomes collisionless and may accelerate protons to energies >10 TeV. Inelastic nuclear collisions of these protons produce an approximately 1 h long flash of TeV neutrinos and 10 GeV photons, about 10 h after the thermal (10 MeV) neutrino burst from the cooling neutron star. A Galactic supernova in a red supergiant star would produce a photon and neutrino flux of approximately 10(-4) erg cm(-2) s(-1). A km(2) neutrino detector will detect approximately 100 muons, thus allowing to constrain both supernova models and neutrino properties.

The Universe is filled with a diffuse background of gamma-ray radiation, the origin of which remains one of the unsolved puzzles of cosmology. Less than one-quarter of the gamma-ray flux can be attributed to unresolved discrete sources, such as active galactic nuclei; the remainder appears to constitute a truly diffuse background. Here we show that the shock waves induced by gravity in the gas of the intergalactic medium, during the formation of large-scale structures like filaments and sheets of galaxies, produce a population of highly relativistic electrons. These electrons scatter a small fraction of the cosmic microwave background photons in the local Universe up to gamma-ray energies, thereby providing the gamma-ray background. The predicted diffuse flux agrees with the observed background across more than four orders of magnitude in photon energy, and the model predicts that the gamma-ray background, though generated locally, is isotropic to better than five per cent on angular scales larger than a degree. Moreover, the agreement between the predicted and observed background fluxes implies a mean cosmological density of baryons that is consistent with Big Bang nucleosynthesis.

Purpose: To evaluate the usefulness of the various culture media used in the traditional workup in infectious keratitis., Methods: Microbiology data sheets from all corneal cultures performed at the University of California Davis Medical Center over a 1-year period were reviewed retrospectively., Results: Bacterial cultures were sent in 76 cases. In 19 cases, culture specimens from ulcers were plated onto blood, chocolate, and inhibitory mold agar and were inoculated into an anaerobic medium. In 58 cases, blood and chocolate agar were sent. In 70% of cases, blood and chocolate agar provided identical information. Inhibitory mold agar was positive twice in 39 plates sent. A fungal pathogen had been identified on chocolate agar plates sent for these cases., Conclusion: In the evaluation of infectious keratitis, plating onto chocolate agar or blood agar alone is a reasonable alternative to sending multiple cultures.

Treatment modalities for prostate cancer include surgery, radiation therapy, and hormonal manipulation. Sexual dysfunction is a potential sequela of these treatments. Ideally, nursing interventions are begun before treatment is initiated. Pertinent questions enable nurses to elicit specific information needed to develop the patient's care plan. Sexual assessment strategies and interventions, such as the PLISSIT model, that can be implemented when caring for these patients are presented.

Cooperative binding of the bacteriophage lambda cI repressor dimer to specific sites of the phage operators OR and OL controls the developmental state of the phage. It has long been believed that cooperativity is mediated by self-assembly of repressor dimers to form tetramers which can then bind simultaneously to adjacent operator sites. As a first step in defining the individual energy contributions to binding cooperativity, sedimentation equilibrium and steady-state fluorescence anisotropy methods have been used to study the higher order assembly reactions of the free repressor in solution. Wild-type repressor with 5-hydroxytryptophan (5-OHTrp) substituted for the native tryptophan [Ross et al. (1992) Proc. Natl. Acad. Sci. U.S.A. 89, 12023-12027] and two mutant repressor proteins that bind cooperatively to OR but have altered dimerization properties were also studied. We report here that the primary assembly mode of all four proteins is dimer to octamer. It is not dimer to tetramer as previously assumed. While tetramer does form as an assembly intermediate, dimer-octamer assembly is a concerted process so that tetramer is never a predominant species in solution. Sedimentation velocity experiments suggest that the octamer is highly asymmetric, consistent with an elongated shape. This conformation could allow octamers to bind simultaneously to all three operator sites at either OR or OL. Examination of tetramer and octamer concentrations suggests that both species could be involved in cooperative repressor-operator interactions. Our previous work used the unique spectral properties of 5-OHTrp to demonstrate that octamer binds single-operator DNA and is not dissociated to tetramer [Laue et al. (1993) Biochemistry 32, 2469-2472]. Taken together with the results presented here, octamers as well as tetramers must be considered in developing models to explain the cooperativity of lambda cI repressor binding to operator DNA.

Ultracentrifugation and fluorescence anisotropy decay measurements were used to evaluate the asymmetry and conformational dynamics of human blood clotting enzyme VIIa (VIIa) and the complex it forms with a soluble truncation mutant of human tissue factor (sTF) which acts as an essential cofactor for VIIa. Sedimentation velocity experiments showed that both VIIa and the sTF.VIIa complex are highly asymmetric. In each case, the friction ratio f/fsphere, is consistent with a family of general elliposids ranging from prolate to oblate. Fluorescence anisotropy decay experiments were used to limit the family of elliposids which can describe the hydrodynamic behavior of VIIa and sTF.VIIa. For both VIIa and the sTF.VIIa complex, the oblate ellipsoid of revolution was eliminated. In addition, the fluorescence anisotropy decay data clearly show that upon binding sTF.VIIa loses a segmental motion involving a domain containing the active site of the enzyme. This suggests that sTF causes a stabilization of a limited range of VIIa conformations. This stabilization may be important for proper recognition of the TF.VIIa substrate, factor X.

We find that the isolated, extracellular domain of tissue factor (TF1-218; sTF) exhibits only 4% of the activity of wild-type transmembrane TF (TF1-263) in an assay that measures the conversion of factor X to Xa by the TF:VIIa complex. Further, the activity of sTF is manifest only when vesicles consisting of phosphatidylserine and phosphatidylcholine (30/70 w/w) are present. To determine whether the decreased activity results from weakened affinity of sTF for VIIa, we studied their interaction using equilibrium ultracentrifugation, fluorescence anisotropy, and an activity titration. Ultracentrifugation of the sTF:VIIa complex established a stoichiometry of 1:1 and an upper limit of 1 nM for the equilibrium dissociation constant (Kd). This value is in agreement with titrations of dansyl-D-Phe-L-Phe-Arg chloromethyl ketone active site labeled VIIa (DF-VIIa) with sTF using dansyl fluorescence anisotropy as the observable. Pressure dissociation experiments were used to obtain quantitative values for the binding interaction. These experiments indicate that the Kd for the interaction of sTF with DF-VIIa is 0.59 nM (25 degrees C). This value may be compared to a Kd of 7.3 pM obtained by the same method for the interaction of DF-VIIa with TF1-263 reconstituted into phosphatidylcholine vesicles. The molar volume change of association was found to be 63 and 117 mL mol-1 for the interaction of DF-VIIa with sTF and TF1-263, respectively. These binding data show that the sTF:VIIa complex is quantitatively and qualitatively different from the complex formed by TF1-263 and VIIa.