Neurotrophic properties of leptomeninges

The leptomeninges, consisted of pia mater and arachnoid, cover the surface of brain parenchyma. Leptomeningeal cells produce a number of biologically active proteins, including prostaglandin-D synthase, cyclooxygenase-1, -2, insulin-like growth factor-II, insulin-like growth factor-binding proten-2, and apolipoprotein E, released into the cerebrospinal fluid. The involvement of leptomeninges in neurotrophic, scavenging, and transport activities as well as inflammatory responses, associated with the brain, is reviewed.Biomedical Reviews 1999; 10: 31-36

NUMERICAL/EXPERIMENTAL INVESTIGATIONS ON INLET BACK FLOW IN A HELICAL INDUCER IN PARTIAL FLOW CONDITIONS

ABSTRACT The attachment of inducer upstream of main impeller is an effective method to improve the suction performance of turbopumps. However, the various types of cavitation instabilities are known to occur even at the designed flow rate as well as in the partial flow rate conditions. The cavitation surge is a viciously unstable phenomenon occurring at partial flow rates, in which all blade cavities are periodically and synchronously elongated and shortened, leading the strong vibration in pump systems. Because the cavitation surge is strongly associated with the inlet back flow of inducer, it is desirable to know the detailed structure of back flow for the development of its effective suppression methods/devices. Then, in the present study, we carried out the numerical and experimental investigations of non-cavitating flows in a two bladed helical inducer with/without an inlet ring plate, which has been found to be effective for the suppression of cavitation surge. The basic characteristics of the inlet back flow structure are obtained and discussed in terms of the occurrence/suppression mechanisms of cavitation surge. Key words: Inducer, Back flow, Computational fluid dynamics, LDV measurement. INTRODUCTION Recently, the miniaturization of turbopumps is expected to reduce the pump space for various fluid systems. Though the high-speed operation is necessary for this purpose, it might lead to the occurrence of cavitaion, then the deterioration of suction performance of turbopumps. The attachment of an inducer upstream of a main impeller is an effective way to achieve the high suction performance in severe cavitation conditions

Advanced Dry Low N0x Combustor for Mitsubishi G Glass Gas Turbines

ABSTRACT Design features and verification results for Mitsubishi Heavy Industries' (MHI) latest gas Dry Low NOx (DLN) combustor technology for 1500ºC G-class gas turbines is presented. Key design improvements include: A) Inlet aerodynamics: CFD based design air inlet for improved flow uniformity into the pre-mixers. B) Fuel/air mixing: integrated fuel injector and swirler to decrease local flame hot-spots and reduce NOx while preventing flashback. C) Combustor aerodynamics: redesigned flame holding baffle and combustor outer wall to achieve better flame stability and NOx reduction. D) Acoustic resonator: two acoustic resonators, one in the liner to prevent high frequency combustion dynamics and the other in the bypass valve for low frequency dynamics. Tests were conducted to verify the new DLN combustor by installing it in a M501G1 gas turbine at MHI's T-Point combined cycle power plant, with more than 1500 special measurements. Following the preliminary verification period the combustor was installed at the same plant for long-term operation. The results demonstrate the following capabilities: A) Less than 15ppm NOx operation with turn down to 60% load. B) Stable combustion dynamics at all load levels. C) High combustor ignition reliability. D) Suitable for daily start and stop (DSS) operation. E) Good reliability and durability. F) Retrofitable to existing 501G and 701G gas turbines

Mast cell activation by pedicellarial toxin of sea urchin, Toxopneustes pileolus

AbstractPedicellarial toxin, partially purified from the sea urchin Toxopneustes pileolus, dose-dependently and time-dependently caused histamine release from rat peritoneal mast cells. Pedicellarial toxin induced a rapid initial rise in [Ca2+]i within several seconds which was followed by a further slower increase of [Ca2+] (second rise). The toxin induced a dose-dependent formation of inositol 1,4,5-triphosphate (IP3) as well as the histamine release in mast cells. Furthermore, the toxin stimulated phosphoinositide-specific phospholipase C (PI-PLC) activity in mast cell membranes. 2-Nitro-4-carboxyphenyl-N,N. -diphenylcarbamate (NCDC), a PLC inhibitor, inhibited the activation of PI-PCL induced by pedicellarial toxin. Cholera toxin inhibited pedicellarial toxin-induced histamine release, whereas pretreatment of pertussis toxin failed to inhibit it. These results suggest that pedicellarial toxin from T. pileolus activates PI-PCL and the stimulation of PI turnover may lead to the release of IP3 into the cytoplasm, resulting in histamine release from rat mast cells

Infected aortic aneurysm and inflammatory aortic aneurysm—In search of an optimal differential diagnosis

SummaryInfected aortic aneurysm and inflammatory aortic aneurysm each account for a minor fraction of the total incidence of aortic aneurysm and are associated with periaortic inflammation. Despite the similarity, infected aortic aneurysm generally shows a more rapid change in clinical condition, leading to a fatal outcome; in addition, delayed diagnosis and misuse of corticosteroid or immunosuppressing drugs may lead to uncontrolled growth of microorganisms. Therefore, it is mandatory that detection of aortic aneurysm is followed by accurate differential diagnosis. In general, infected aortic aneurysm appears usually as a saccular form aneurysm with nodularity, irregular configuration; however, the differential diagnosis may not be easy sometimes for the following reasons: (1) symptoms, such as abdominal and/or back pain and fever, and blood test abnormalities, such as elevated C-reactive protein and enhanced erythrocyte sedimentation rate, are common in infected aortic aneurysm, but they are not found infrequently in inflammatory aortic aneurysm; (2) some inflammatory aortic aneurysms are immunoglobulin (Ig) G4-related, but not all of them; (3) the prevalence of IgG4 positivity in infected aortic aneurysm has not been well investigated; (4) enhanced uptake of 18F-fluorodeoxyglucose (FDG) by 18F-FDG-positron emission tomography may not distinguish between inflammation mediated by autoimmunity and that mediated by microorganism infection. Here we discuss the characteristics of these two forms of aortic aneurysm and the points of which we have to be aware before reaching a final diagnosis