Stony Brook University

About: Stony Brook University is a education organization based out in Stony Brook, New York, United States. It is known for research contribution in the topics: Population & Poison control. The organization has 32534 authors who have published 68218 publications receiving 3035131 citations. The organization is also known as: State University of New York at Stony Brook & SUNY Stony Brook.

Dynamic control of positional information in the early Drosophila embryo

Abstract: Morphogen gradients contribute to pattern formation by determining positional information in morphogenetic fields. Interpretation of positional information is thought to rely on direct, concentration-threshold-dependent mechanisms for establishing multiple differential domains of target gene expression. In Drosophila, maternal gradients establish the initial position of boundaries for zygotic gap gene expression, which in turn convey positional information to pair-rule and segment-polarity genes, the latter forming a segmental pre-pattern by the onset of gastrulation. Here we report, on the basis of quantitative gene expression data, substantial anterior shifts in the position of gap domains after their initial establishment. Using a data-driven mathematical modelling approach, we show that these shifts are based on a regulatory mechanism that relies on asymmetric gap-gap cross-repression and does not require the diffusion of gap proteins. Our analysis implies that the threshold-dependent interpretation of maternal morphogen concentration is not sufficient to determine shifting gap domain boundary positions, and suggests that establishing and interpreting positional information are not independent processes in the Drosophila blastoderm.

Development and preliminary evaluation of the social problem-solving inventory

Abstract: The Social Problem-Solving Inventory (SPSI) is a 70-item, multidimensional, self-report measure of social problem-solving ability that is based on the prescriptive model developed previously by D'Zurilla and his associates. From samples of undergraduate college students and middle-aged community residents, preliminary data concerning the reliability and validity of the SPSI are presented

Nerve growth factor-induced hyperalgesia in the neonatal and adult rat

Abstract: Recently, we have shown that the interaction between NGF and sensory neurons in early postnatal periods is restricted to nociceptive afferents (Ritter et al., 1991; Lewin et al., 1992a; Ritter and Mendell, 1992). Here we show that administration of excess NGF to neonatal or mature animals can lead to a profound behavioral hyperalgesia. Neonatal NGF treatment (postnatal day 0-14) resulted in a profound mechanical hyperalgesia that persisted until the animals had reached maturity (6 weeks of age). This hyperalgesia could be explained by an NGF-mediated sensitization of A delta nociceptive afferents to mechanical stimuli. This peripheral sensitization wore off with a time course similar to that of the behavior hyperalgesia. Treatment of animals from the second postnatal week until 5 weeks of age (juveniles) led to a very similar behavioral hyperalgesia; however, there was no corresponding sensitization of A delta nociceptors to mechanical stimuli. Finally, one group of adult animals (5 weeks old) was treated daily with single injections of NGF for between 1 and 4 d. Within 24 hr after the first NGF injection these animals developed a mechanical hyperalgesia of the same magnitude seen after neonatal and juvenile NGF treatments. No sensitization of A delta nociceptive afferents was observed in these animals. In addition to the mechanical hyperalgesia, the animals also developed a heat hyperalgesia after one injection of NGF. The heat hyperalgesia was apparent within 15 min after the injection; however, signs of mechanical hyperalgesia were not seen until 6 hr after the injection. In conclusion, it appears that the NGF-induced mechanical hyperalgesia is brought about by different mechanisms in neonatal and adult rats. Furthermore, in adult animals the NGF-induced mechanical and heat hyperalgesia also appear to be attributable to two different mechanisms. The mechanical hyperalgesia may be due to central changes (see Lewin et al., 1992b), whereas the heat hyperalgesia is likely to result at least in part from the sensitization of peripheral receptors to heat.

How does a drug molecule find its target binding site

Abstract: Although the thermodynamic principles that control the binding of drug molecules to their protein targets are well understood, detailed experimental characterization of the process by which such binding occurs has proven challenging. We conducted relatively long, unguided molecular dynamics simulations in which a ligand (the cancer drug dasatinib or the kinase inhibitor PP1) was initially placed at a random location within a box that also contained a protein (Src kinase) to which that ligand was known to bind. In several of these simulations, the ligand correctly identified its target binding site, forming a complex virtually identical to the crystallographically determined bound structure. The simulated trajectories provide a continuous, atomic-level view of the entire binding process, revealing persistent and noteworthy intermediate conformations and shedding light on the role of water molecules. The technique we employed, which does not assume any prior knowledge of the binding site's location, may prove particularly useful in the development of allosteric inhibitors that target previously undiscovered binding sites.

Structure and elastic properties of quartz at pressure

Abstract: Unit cells and crystal structures were determined on a single crystal of quartz at seven pressures from I atm to 61.4 kbar. Unit-cell parameters are a:4'916(l) and c : 5.a054(4)A at I atm, and a: 4.7O22(3) and c : 5.2561Q)A at 61.4 kbar. Structural changes observed over this pressure range include a decrease in the Si-O-Si angle ftom 143.73(7)" to 134.2(l)"' a decrease in the average Si-O bond distance from 1.6092(7) to 1.605(l)A, and an increase in distortion ofthe silicate tetrahedron. Several O-O distances show very large changes (ll7a) that can be related to the unit-cell-edge compression. As pressure is increased, the geometry of the SiO, (quartz) structure approaches that of the low-pressure GeO, (quartz) structure. The structural changes that take place with increased temperature are not the inverses of those that occur with increased pressure; changes in the Si-O-Si angle and the tetrahedral tilt angle control thermal expansion, whereas smaller changes in the Si-O-Si angle and tetrahedral distortion control isothermal compression. By constraining the zero-pressure bulk modulus to be equal to that calculated from acoustic data [K, : 0.371(2) Mbar], the pressure derivative of the bulk modulus at Tnro pressure tKi : 6.2(l)l has been calculated by fitting the P-V data to a Birch-Murnaghan equation of state. The anomalously low value of Poisson's ratio in quartz can be explai-ned by the low ratio of the off-diagonal shear moduli to the pure-shear moduli. This small ratio reflects the easily expandin! or contracting spirals of tetrahedra that behave like coiled springs.