Search Results - (Author, Cooperation:T. Kendall)

2018-02-08

The American Society for Biochemistry and Molecular Biology (ASBMB)

0021-9258

1083-351X

Biology

Chemistry and Pharmacology

2014-10-04

American Association for the Advancement of Science (AAAS)

0036-8075

1095-9203

Biology

Chemistry and Pharmacology

Computer Science

Medicine

Natural Sciences in General

Physics

Animals ; *Carnivora ; *Energy Metabolism ; *Predatory Behavior ; Puma/*metabolism/*psychology ; Running

1471-4159

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

Abstract: Primary cultures of neonatal murine brain have been reported to express multiple receptors that regulate adenylate cyclase activity. Since for the most part these results were obtained with mixed cell cultures, it has been difficult to define receptor profiles for specific cell types. With this concern in mind a series of studies has been initiated designed to identify specific receptors present on highly purified, immunocytochemically defined astroglia derived from the cerebral cortices of neonatal rats. In this study the capacity of a variety of peptide hormones to regulate cyclic AMP metabolism in these cells was examined. Fibroblasts derived from the meninges represent a predictable source of contamination in primary CNS culture. Thus, to assign more clearly specific receptors to the astroglial cell population, receptor-mediated regulation of cyclic AMP accumulation was also examined in fibroblasts. Cyclic AMP accumulation in astroglia was stimulated by catecholamines (acting at β1,- adrenergic receptors), prostaglandin E1, vasoactive intestinal polypeptide, α-melanocyte-stimulating hormone, and adrenocorticotropin. Bombesin, luteinizing hormonereleasing hormone, neurotensin, thyrotropin-releasing hormone, somatostatin, secretin, and vasopressin did not significantly increase cyclic AMP levels in these cultures. Catecholamines, acting at α2-adrenergic receptors, and somatostatin inhibited agonist-stimulated cyclic AMP ac cumulation. In meningeal cell cultures catecholamines (acting at β2- and α2-adrenergic receptors) and prostaglandin E1, regulated cyclic AMP levels. However, vasoactive intestinal peptide did not stimulate and somatostatin did not inhibit cyclic AMP accumulation in these cells.

Electronic Resource

1749-6632

Blackwell Publishing Journal Backfiles 1879-2005

Natural Sciences in General

Electronic Resource

1749-6632

Blackwell Publishing Journal Backfiles 1879-2005

Natural Sciences in General

Electronic Resource

1545-9985

Nature Archives 1869 - 2009

Biology

Medicine

[Auszug] Although diverse signaling cascades require the coordinated regulation of heterotrimeric G proteins and small GTPases, these connections remain poorly understood. We present the crystal structure of the GTPase Rac1 bound to phospholipase C-β2 (PLC-β2), a classic effector of heterotrimeric ...

Electronic Resource

1072-8368

Nature Archives 1869 - 2009

Biology

Medicine

[Auszug] GTP-bound subunits of the Gq family of Gα subunits directly activate phospholipase C-β (PLC-β) isozymes to produce the second messengers inositol 1,4,5-trisphosphate and diacylglycerol. PLC-βs are GTPase activating proteins (GAPs) that also promote the formation of GDP-bound, ...

Electronic Resource

0021-9541

Life and Medical Sciences ; Cell & Developmental Biology

Wiley InterScience Backfile Collection 1832-2000

Biology

Medicine

Platelet-derived growth factor (PDGF) and angiotensin II (All) are thought to mediate their biological effects in vascular smooth muscle cells (VSMCs) by causing alterations in cytosolic free calcium ([Ca2+]i). In this study we examine the pathways by which PDGF and All alter [Ca2 +]i in VSMCs. Addition of PDGF resulted in a rapid, transient, concentration-dependent increase in [Ca2+]i; this rise in [Ca2 +]i was blocked completely by preincubation of cells with ethylene glycol-bis (β-aminoethyl ether) N,N,N′,N′-tetraacetic acid (EGTA) or CoCl2, by the voltage-sensitive Ca2 +-channel antagonists verapamil or nifedipine, by 12-O-tetradecanoylphorbol-13-acetate (TPA), or by pertussis toxin. All also caused an increase in [Ca2 +]i; however, All-stimulated alterations in [Ca2+]i displayed different kinetics compared with those caused by PDGF. Pretreatment of cells with 8-(diethylamine)-octyl-3,4,5-trimethyoxybenzoate hydrochloride (TMB-8), almost totally inhibited All-induced increases in [Ca2+]i. EGTA or CoCl2 only slightly diminished All-stimulated increases in [Ca2+]i. Nifedipine, verapamil, TPA, and pertussis toxin pretreatment were without effect on All-induced increases in [Ca2+]i. PDGF and All both stimulated increases in total inositol phosphate accumulation, although the one-half maximal concentration (ED50) for alterations in [Ca2+]i and phosphoinisitide hydrolysis differed by a factor of 10 for PDGF (3 × 10-10 M for Ca2+ vs. 2.5 × 10-9 M for phosphoinositide hydrolysis), but they were essentially identical for All (7.5 × 10-9 M for Ca2+ vs. 5.0 × 10-9 M for phosphoinositide hydrolysis). PDGF stimulated mitogenesis (as measured by [3H]-thymidine incorporation into DNA) in VSMCs with an ED50 similar to that for PDGF-induced alterations in phosphoinositide hydrolysis. PDGF-stimulated mitogenesis was blocked by pretreatment of cells with voltage-sensitive Ca2 + channel blockers, TPA, or pertussis toxin. These results suggest that PDGF and All cause alterations in [Ca2+]i in VSMCs by at least quantitatively distinct mechanisms. PDGF binding activates a pertussis-toxin-sensitive Ca2+ influx into cells via voltage-sensitive Ca2+ channels (blocked by EGTA, verapamil, and nifedipine), as well as stimulating phosphoinositide hydrolysis leading to release of Ca2+ from intracellular stores. All-induced alterations in [Ca2+]i are mainly the result of phosphoinositide hydrolysis and consequent entry of Ca2+ into the cytoplasm from intracellular stores. Our data also suggest that changes in [Ca2 +]i caused by PDGF are required for PDGF-stimulated mitogenesis.

4 Ill.

Electronic Resource

0021-9541

Life and Medical Sciences ; Cell & Developmental Biology

Wiley InterScience Backfile Collection 1832-2000

Biology

Medicine

The ability of isoproterenol, glucagon, PGE1 and cholera toxin to stimulate the synthesis of cAMP and protein kinase activity in a line of liver cells (BRL) and a line of rat hepatoma cells (H35) has been determined.The concentration of cAMP in BRL cells (∼ 10 pmoles/mg protein) is in the range reported for other cultured cell lines but H35 cells contain extraordinarily low amounts of this cyclic nucleotide (∼ 0.05 pmoles/mg protein). Isoproterenol and PGE1 caused an increase in cAMP content, and protein kinase activation in BRL cells, although glucagon was ineffective. H35 cells, in contrast, were completely insensitive to all hormonal agonists. Despite this fact, cholera toxin was able to produce a marked increase in cAMP content, adenylate cyclase activity and protein kinase activation in H35 cells. Binding studies with [125I]-iodohydroxybenzylpindolol, a specific β-adrenergic receptor antagonist, revealed that each H35 cell possesses fewer than 10 β-adrenergic receptors whereas BRL cells contain 2-5,000 receptors per cell. The low level of cAMP in H35 cells appears to result from a combination of totally unstimulated adenylate cyclase and apparently elevated phoshodiesterase activities.

1 Ill.

Electronic Resource

1089-7690

AIP Digital Archive

Physics

Chemistry and Pharmacology

Canonical ensemble molecular dynamics simulations were conducted for methane diffusion in AlPO4-5 in order to assess the role of the lattice motion on adsorbate diffusivity in straight pore zeolites. Both a static lattice model and a full dynamic lattice model were used at a loading of 1.5 methane/unit cell at 295 K. Although recent simulation work has asserted that there should be a difference, we show that there is little difference in the observed methane diffusivity (1.26×10−7 m2/s) and passing frequency (0.305) when a static lattice approximation is used over a full dynamic lattice (1.33×10−7 m2/s and 0.328). Furthermore, we introduce a methodology for handling lattice motion in molecular simulations by utilizing the normal vibrational modes in a harmonic crystal approximation. © 2000 American Institute of Physics.

Electronic Resource

1089-7690

AIP Digital Archive

Physics

Chemistry and Pharmacology

We have conducted a first principles density functional theory (DFT) calculation to explore the electronic structure of sodalite at various stages of Al-substitution. By calculating the electronic structure of both substituted and unsubstituted frameworks, with and without the presence of extra-framework atoms, we show that Al-substitution and cation compensation essentially affect the electronic structure only at the upper valence band edge (i.e., the frontier orbitals of reactivity theory). In addition, we show that the equilibrium positions of the extra-framework cations are located in the vicinity of the frontier orbitals which are preferentially localized near aluminum. © 1998 American Institute of Physics.

Electronic Resource

1573-868X

Springer Online Journal Archives 1860-2000

Geosciences

Abstract The origin of a western boundary current as a jet is accounted for by a transfer of potential energy to kinetic energy, and poleward changes along the western boundary are directly correlated to variation in Coriolis parameter.

Electronic Resource

1573-868X

Springer Online Journal Archives 1860-2000

Geosciences

Abstract Large fluctuation in transport of the Equatorial Countercurrent flowing eastward from the western boundary is not the direct result of fluctuation in transport of the North Equatorial Current, but rather relates to fluctuation of sea level anomaly in the Philippine Sea.

Electronic Resource

1572-9508

atmospheric ; Čerenk technique ; gamma ray astronomy ; gamma ray telescopes

Springer Online Journal Archives 1860-2000

Physics

Abstract The design, construction and operation of the University of Durham ground-based gamma ray telescope is discussed. The telescope has been designed to detect gamma rays in the ≤ 200 GeV region and to achieve good discrimination between gamma ray and hadron initiated showers in the higher energy region (≳ 300 GeV). The telescope was commissioned in 1995 and a description of its design and operation is presented, together with a verification of the telescope's performance.

Electronic Resource