Spreading waves of a reduced diffusion coefficient of water in normal and ischemic rat brain

Using echo planar diffusion-weighted magnetic resonance imaging, we measured three-dimensional changes in the apparent diffusion coefficient (ADC) of water in eight contiguous coronal slices, encompassing the entire rat brain, before and after local cortical stimulation. We applied chemical (potassium chloride application; n = 6) and mechanical (needle stab; n = 4) stimulations to the right posterior parietal rat cortex. In all animals in which potassium chloride or the needle stab was applied, a region of decreased ADC values to a mean of 0.45 +/- 0.03 x 10(-5)cm2/s occurred. These reduced ADC levels appeared in the posterior parietal cortex within 1 min after cortical stimulation and the change recovered within 1 min. Then a ripple-like movement of similar changes developed across the unilateral cortex. This change was localized to the cortex and no significant ADC changes occurred in subcortical structures. The propagating speed of this movement was 3.4 +/- 0.5 mm/min. These findings are compatible with spreading depression as observed electrophysiologically. Similar ADC changes occurred in areas distinct from the ischemic lesion in 3 of 12 animals subjected to focal cerebral ischemia. This magnetic resonance method could detect spreading ADC decline if it occurred in human diseases including brain ischemia.     

Mechanical vibrations induced on elastic structures by piezopolymertransducers

Theoretical and experimental results are presented to analyze the mechanical vibrations of elastic structures activated by piezopolymer transducers. Elastic thin plates and cylindrical shell structures are activated by polyvinylidene fluoride piezoelectric films. Vibrational behavior of activated structures are observed in gaseous and liquid surrounding media. These structures have been considered in view of applications for protection of oceanographic sensors against marine fouling by mechanical surface vibrations     

Differences detected in vivo between samples of aflatoxincontaminated peanut meal, following decontamination by two ammonia-based processes

A sample of peanut meal, highly contaminated with aflatoxins, has been subjected to decontamination by two commercial ammonia-based processes. The original contaminated and the two decontaminated meals were fed to rats for 90 days. No lesions associated with aflatoxin-induced hepatocarcinogenesis were detected histologically following feeding with the two detoxified meals. There were, however, clear differences between the two meals in respect of growth rates of the rats. In addition, feeding one of the detoxified meals resulted in hepatic abnormalities detected using novel immunohistochemical reagents. Differences between the two detoxified meals were also indicated by the results of studies using meals 'spiked' with [¹⁴C]-aflatoxin B₁ prior to being subjected to the detoxification processes. The meals differed in the bioavailability of the label. It was concluded that peanut meal where an initial, unacceptable level of contamination with aflatoxins had been reduced by two ammonia-based processes to comparable, acceptable levels, may still have different effects in vivo when incorporated into animal diets.     

Naloxone attenuates serum corticosterone and augments serum glucose concentrations in broilers stimulated with adrenocorticotropin

The effects of exogenous naloxone and adrenocorticotropin (ACTH) on circulating concentrations of corticosterone and glucose in broilers were determined. Birds were injected i.m. at 0 and 2 h with either saline or naloxone, then i.v. at 2.5 h with either saline or ACTH. Control birds received saline at each injection. Blood samples were taken before the experiment started (0 min) and 30, 60, and 90 min after the last injection. Intramuscular injections of naloxone significantly reduced subsequent ACTH-stimulated increases in serum corticosterone; however, when followed by saline, naloxone elevated corticosterone by 90 min after the final injection of saline. Glucose levels were significantly elevated at 60 min in birds receiving ACTH i.v., but remained elevated through 90 min in birds pretreated with naloxone. Naloxone pretreatment attenuated serum corticosterone but augmented serum glucose concentrations in ACTH-stimulated broilers.     

Effects of type of input and type of processing on recall hypermnesia.

120 undergraduates participated in 1 of 6 conditions representing 2 types of input (words, pictures) and 3 types of initial processing, including imagery (generate object imagery or real-world imagery), semantic (rate pleasantness or form a verbal association), and physical (rate complexity or judge the presence of a feature). After viewing 70 items, Ss attempted to recall them 4 times. Except for physical processing of words, the number of items correctly recalled improved over trials, demonstrating hypermnesia. Intrusions increased over trials in most conditions and appeared later within a trial for words than for pictures. Of 5 alternative accounts of hypermnesia, results favor the sensory/semantic model of memory coding. (French abstract) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Drug metabolism and morphologic changes in the liver of nafenopin-treated rats

Nafenopin (2-methyl-2[p-(1,2,3,4-tetrahydro-1-naphthyl) phenoxy] propionic acid), a phenolic ether with hypolipidemic properties, given to rats of both sexes for 3 or 14 days, caused an increase in liver weight, peroxisome (microbody) proliferation and smooth endoplasmic reticulum accumulation in hepatocytes. In females, 3 days of nafenopin administration elicited a significant reduction of zoxazolamine paralysis time and an enhancement of its metabolism by the 9,000 g supernatant fraction of the liver. In contrast, treatment of males resulted in a prolongation of paralysis and a decrease of zoxazolamine hydroxylation. The serum cholesterol and triglyceride levels were not changed by short-term administration of the hypolipidemic drug to female rats, but there was a lowering of triglycerides in the males. Given for 14 days, nafenopin reduced paralysis time to the same extent in both sexes. The in vitro metabolism of zoxazolamine was similar to that observed after short-term nafenopin administration. A significant fall in serum triglycerides was noted in both females and males. The sex difference in zoxazolamine metabolism was not dependent on endogenous testosterone.     

Tyrosine-containing activation motif-dependent phagocytosis in mast cells

FcR capable of triggering cell activation share with BCR and TCR a conserved intracytoplasmic tyrosine-containing activation motif (TAM). Besides cell activation, these receptors trigger other biologic responses, such as endocytosis of soluble ligands. Murine mast cells express two types of FcR that, when aggregated by antibodies and multivalent Ag, trigger the release of inflammatory mediators and cytokines. These are high affinity receptors for IgE (Fc epsilon RI) and low affinity receptors for IgG (Fc gamma RIII). They comprise each an IgE- or IgG-binding alpha-subunit and two TAM-containing subunits that associate with both receptors: a beta-subunit and a homodimeric gamma-subunit that can associate also with the other subunits of the TCR. Herein, we focused on biologic activities triggered in mast cells via the TAM of the gamma-subunits. Using rat basophilic leukemia (RBL) cells stably transfected with cDNA-encoding murine Fc gamma RIII alpha, we found that murine Fc gamma RIII trigger the phagocytosis of antibody-coated erythrocytes. Using RBL transfectants expressing Fc gamma RIII with a deletion of the intracytoplasmic domain of Fc gamma RIII alpha or chimeric receptors having the extracellular and transmembrane domains of Fc gamma RII and the intracytoplasmic domain of Fc gamma RIII alpha, we showed that intracytoplasmic sequences of Fc gamma RIII alpha are neither necessary nor sufficient for Fc gamma RIII to trigger phagocytosis. Using RBL transfectants expressing chimeric receptors having the extracellular and transmembrane domains of Fc gamma RII and the TAM-containing intracytoplasmic domain of murine Fc gamma RIII gamma, we demonstrated that intracytoplasmic sequences of Fc gamma RIII gamma are sufficient to trigger phagocytosis. Using RBL transfectants expressing the same Fc gamma RII-III gamma chimeras, in the TAM of which one, the other, or both tyrosine residues were mutated, we established that tyrosines in the TAM sequence are required for phagocytosis. Our results endow TAM gamma with previously unknown triggering capacities and Fc gamma RIII with new biologic properties.     

The same tyrosine-based inhibition motif, in the intracytoplasmic domain of Fc gamma RIIB, regulates negatively BCR-, TCR-, and FcR-dependent cell activation

The cell-triggering properties of BCR, TCR and FcR depend on structurally related immunoreceptor tyrosine-based activation motifs (ITAMs). Fc gamma RIIB have no ITAM and do not trigger cell activation. When coaggregated to BCR, they inhibit B cell activation. We show here that, when coaggregated to these receptors, Fc gamma RIIB inhibit Fc epsilon RI-, Fc gamma RIIA-, and TCR-dependent cell activation. Inhibition also affected cell activation by single ITAMs, in isolated FcR or TCR subunits. The same tyrosine-based inhibitory motif (ITIM), which is highly conserved in murine and human Fc gamma RIIB and that was previously shown to inhibit BCR-dependent B cell activation, was required to regulate TCR- and FcR-dependent cell activation. Our findings endow Fc gamma RIIB, and thus IgG antibodies, with general immunoregulatory properties susceptible to act on all ITAM-containing receptors.     

Renal arteries and renal parenchyma in arterial hypertension in pregnancy

Hypertensives in pregnancy are not so grossly distinct and different from adult hypertensives if reference is made to the underlying arterial anomalies and malformations of the parenchyma and their incidence. It is, however, in this group that the limited way in which the active remnant of parenchyma, once constrained by these anomalies, can compensate for the changes in pressure and volume sensitivity imposed by pregnancy is most evident; these changes may be caused by pyelonephritis of pregnancy (genuine but rare), eclampsia of the primigravida, progressive hypertension in the multigravida, or certain cases of late hypertension, menopausal hypertension, or hypertension as a late result of a simple juvenile eclampsia. This series contains a particularly high percentage (21%) of cases of hypertension due to unilateral renal arterial ischaemia which are curable.     

Pressure Relief Design and Performance of Metal Oxide Surge Arresters

Surge arresters with porcelain housing must not have explosive breakage of the housing to minimize damage to other equipment when subjected to internal high short circuit currents. Also, arrester porcelain housings are generally susceptible to undesirable thermal shock. As a solution, this paper describes pressure relief design and performance of arresters equipped with a fiber reinforced plastic tube and an optimum pressure relief nozzle. The arresters showed satisfactory performance during a newly developed synthetic pressure relief test using a 25 kA symmetrical rms current with the first half-cycle fully offset.