Autocrine or paracrine inflammatory actions of corticotropin-releasing hormone in vivo

Corticotropin-releasing hormone (CRH) functions as a regulator of the hypothalamic-pituitary-adrenal axis and coordinator of the stress response. CRH receptors exist in peripheral sites of the immune system, and CRH promotes several immune functions in vitro. The effect of systemic immunoneutralization of CRH was tested in an experimental model of chemically induced aseptic inflammation in rats. Intraperitoneal administration of rabbit antiserum to CRH caused suppression of both inflammatory exudate volume and cell concentration by approximately 50 to 60 percent. CRH was detected in the inflamed area but not in the systemic circulation. Immunoreactive CRH is therefore produced in peripheral inflammatory sites where, in contrast to its systemic indirect immunosuppressive effects, it acts as an autocrine or paracrine inflammatory cytokine.     

Heterogeneous reaction probabilities, solubilities, and the physical state of cold volcanic aerosols

On 19 January 1992, heterogeneous loss of HNO(3), ClNO(3), and HCl was observed in part of the Mount Pinatubo volcanic cloud that had cooled as a result of forced ascent. Portions of the volcanic cloud froze near 191 kelvin. The reaction probability of ClNO(3) and the solubility of HNO(3) were close to laboratory measurements on liquid sulfuric acid. The magnitude of the observed loss of HCl suggests that it underwent a heterogeneous reaction. Such reactions could lead to substantial loss of HCl on background sulfuric acid particles and so be important for polar ozone loss.     

Vapor pressures of solid hydrates of nitric Acid: implications for polar stratospheric clouds

Thermodynamic data are presented for hydrates of nitric acid: HNO(3).H(2)O, HNO(3).2H(2)O, HNO(3).3H(2)O, and a higher hydrate. Laboratory data indicate that nucleation and persistence of metastable HNO(3).2H(2)O may be favored in polar stratospheric clouds over the slightly more stable HNO(3).3H(2)O. Atmospheric observations indicate that some polar stratospheric clouds may be composed of HNO(3).2H(2)O and HNO(3).3H(2)O. Vapor transfer from HNO(3).2H(2)O to HNO(3).3H(2)O could be a key step in the sedimentation of HNO(3), which plays an important role in the depletion of polar ozone.     

Iceberg discharges into the north atlantic on millennial time scales during the last glaciation

High-resolution studies of North Atlantic deep sea cores demonstrate that prominent increases in iceberg calving recurred at intervals of 2000 to 3000 years, much more frequently than the 7000-to 10,000-year pacing of massive ice discharges associated with Heinrich events. The calving cycles correlate with warm-cold oscillations, called Dansgaard-Oeschger events, in Greenland ice cores. Each cycle records synchronous discharges of ice from different sources, and the cycles are decoupled from sea-surface temperatures. These findings point to a mechanism operating within the atmosphere that caused rapid oscillations in air temperatures above Greenland and in calving from more than one ice sheet.     

Timing of hot spot--related volcanism and the breakup of madagascar and India

Widespread basalts and rhyolites were erupted in Madagascar during the Late Cretaceous. These are considered to be related to the Marion hot spot and the breakup of Madagascar and Greater India. Seventeen argon-40/argon-39 age determinations reveal that volcanic rocks and dikes from the 1500-kilometer-long rifted eastern margin of Madagascar were emplaced rapidly (mean age = 87.6 +/- 0.6 million years ago) and that the entire duration of Cretaceous volcanism on the island was no more than 6 million years. The evidence suggests that the thick lava pile at Volcan de l'Androy in the south of the island marks the focal point of the Marion hot spot at approximately 88 million years ago and that this mantle plume was instrumental in causing continental breakup.     

The needle length of bacterial injectisomes is determined by a molecular ruler

Size determination represents a fundamental requirement for multicomponent biological structures. Some pathogenic bacteria possess a weapon derived from the flagellum. Like the flagellum, this type-III secretion apparatus, called the injectisome, has a transmembrane basal body, but the external component is a needle-like structure instead of a hook and a filament. Here, we provide evidence that the length of this needle is determined by the size of a protein, YscP, acting as a molecular ruler.     

Relapse to cocaine-seeking after hippocampal theta burst stimulation

Treatment efforts for cocaine addiction are hampered by high relapse rates. To map brain areas underlying relapse, we used electrical brain stimulation and intracranial injection of pharmacological compounds after extinction of cocaine self-administration behavior in rats. Electrical stimulation of the hippocampus containing glutamatergic fibers, but not the medial forebrain bundle containing dopaminergic fibers, elicited cocaine-seeking behavior dependent on glutamate in the ventral tegmental area. This suggests a role for glutamatergic neurotransmission in relapse to cocaine abuse. The medial forebrain bundle electrodes supported intense electrical self-stimulation. These findings suggest a dissociation of neural systems subserving positive reinforcement (self-stimulation) and incentive motivation (relapse).