The status of the genera Hysterolecithoides Yamaguti, 1934, Neotheletrum Gibson & Bray, 1979 and Machidatrema Leon-Regagnon, 1998 (Digenea : Hemiuroidea), including a description of M. leonae n. sp from Australian waters

A diagnosis is given for the lecithasterid genus Hysterolecithoides Yamaguti, 1934, which is now found to have two to six (possibly seven) vitelline masses. The species H. frontilatus (Manter, 1969) is returned to the genus, having been considered a member of the bunocotylid genus Neotheletrum by recent authors. It is redescribed from Siganus nebulosus, Moreton Bay, and S. doliatus, Lizard Island, Great Barrier Reef and New Caledonia, with emphasis on the presence of Juel's organ, a uterine seminal receptacle and the blind sac associated with the genital atrium. It differs from its congeners in the trajectory of the pars prostatica which recurves dorsally to the sinus-sac. Oligolecithoides Shen, 1982 is synonymised with Hysterolecithoides and O. trilobatus Shen, 1982 is synomised with H. epinepheli Yamaguti, 1934. Machidatrema Leon-Regagnon, 1998 is diagnosed, and found to be close to Hysterolecithoides, but differs in the lack of a blind-sac projecting from the dorsal genital atrium, by its tandem testes, the coiling of the uterus between the testes and the ovary, and the ventral excretory pore. M. leonae n. sp. is described from Siganus fuscescens, S. lineatus, S. doliatus, S. corallinus, S. vulpinus and Scarus globiceps at Heron Island, Queensland. It differs from its closest congener, M. akeh, in the muscular and tegumental flap over the genital pore and details of the terminal genitalia. M. chilostoma (Machida, 1980) and M. kyphosi (Yamaguti, 1970) are redescribed from Kyphosus vaigiensis from Heron Island. Neotheletrum Gibson & Bray, 1979 is diagnosed: it differs from Hysterolecithoides in its confluent excretory arms, blind seminal receptacle (no Juel's organ) and uniformly tripartite vitellarium. A cladistic analysis suggests that M. chilostoma and M. kyphosi are not best accommodated in Machidatrema, that Machidatrema (sensu stricto) is monophyletic and that Hysterolecithoides is paraphyletic. Hysterolecithoides and Machidatrema are considered hysterolecithine lecithasterids, whilst Neotheletrum is retained as an opisthadenine bunocotylid.

Strain-dependent fluid flow defined through rock mass classification schemes

Strain-dependent hydraulic conductivities are uniquely defined by an environmental factor, representing applied normal and shear strains, combined with intrinsic material parameters representing mass and component deformation moduli, initial conductivities, and mass structure. The components representing mass moduli and structure are defined in terms of RQD (rock quality designation) and RMR (rock mass rating) to represent the response of a whole spectrum of rock masses, varying from highly fractured (crushed) rock to intact rock. These two empirical parameters determine the hydraulic response of a fractured medium to the induced-deformations The constitutive relations are verified against available published data and applied to study one-dimensional, strain-dependent fluid flow. Analytical results indicate that both normal and shear strains exert a significant influence on the processes of fluid flow and that the magnitude of this influence is regulated by the values of RQD and RMR.

Sporadic and familial pheochromocytomas are associated with loss of at least two discrete intervals on chromosome 1p

Pheochromocytomas are tumors of the adrenal medulla originating in the chromaffin cells derived from the neural crest. Ten % of these tumors are associated with the familial cancer syndromes multiple endocrine neoplasia type 2, von Hippel-Lindau disease (VHL), and rarely, neurofibromatosis type 1, in which germ-line mutations have been identified in RET, VHL, and NF1, respectively. In both the sporadic and familial forms of pheochromocytoma, allelic loss at 1p, 3p, 17p, and 22q has been reported, yet the molecular pathogenesis of these tumors is largely unknown. Allelic loss at chromosome 1p has also been reported in other endocrine tumors, such as medullary thyroid cancer and tumors of the parathyroid gland, as well as in tumors of neural crest origin including neuroblastoma and malignant melanoma, In this study, we performed fine structure mapping of deletions at chromosome 1p in familial and sporadic pheochromocytomas to identify discrete regions likely housing tumor suppressor genes involved in the development of these tumors. Ten microsatellite markers spanning a region of similar to 70 cM (Ipter to 1p34.3) were used to screen 20 pheochromocytomas from 19 unrelated patients for loss of heterozygosity (LOH). LOH was detected at five or more loci in 8 of 13 (61%)sporadic samples and at five or more loci in four of five (80%) tumor samples from patients with multiple endocrine neoplasia type 2. No LOH at 1p was detected in pheochromocytomas from two VHL patients, Analysis of the combined sporadic and familial tumor data suggested three possible regions of common somatic loss, designated as PCI (D1S243 to D1S244), PC2 (D1S228 to D1S507), and PC3 (D1S507 toward the centromere). We propose that chromosome Ip may be the site of at least three putative tumor suppressor loci involved in the tumorigenesis of pheochromocytomas. At least one of these loci, PC2 spanning an interval of <3.8 cM, is Likely to have a broader role in the development of endocrine malignancies.

Finite element modeling of fluid-rock interaction problems in pore-fluid saturated hydrothermal/sedimentary basins

In order to use the finite element method for solving fluid-rock interaction problems in pore-fluid saturated hydrothermal/sedimentary basins effectively and efficiently, we have presented, in this paper, the new concept and numerical algorithms to deal with the fundamental issues associated with the fluid-rock interaction problems. These fundamental issues are often overlooked by some purely numerical modelers. (1) Since the fluid-rock interaction problem involves heterogeneous chemical reactions between reactive aqueous chemical species in the pore-fluid and solid minerals in the rock masses, it is necessary to develop the new concept of the generalized concentration of a solid mineral, so that two types of reactive mass transport equations, namely, the conventional mass transport equation for the aqueous chemical species in the pore-fluid and the degenerated mass transport equation for the solid minerals in the rock mass, can be solved simultaneously in computation. (2) Since the reaction area between the pore-fluid and mineral surfaces is basically a function of the generalized concentration of the solid mineral, there is a definite need to appropriately consider the dependence of the dissolution rate of a dissolving mineral on its generalized concentration in the numerical analysis. (3) Considering the direct consequence of the porosity evolution with time in the transient analysis of fluid-rock interaction problems; we have proposed the term splitting algorithm and the concept of the equivalent source/sink terms in mass transport equations so that the problem of variable mesh Peclet number and Courant number has been successfully converted into the problem of constant mesh Peclet and Courant numbers. The numerical results from an application example have demonstrated the usefulness of the proposed concepts and the robustness of the proposed numerical algorithms in dealing with fluid-rock interaction problems in pore-fluid saturated hydrothermal/sedimentary basins. (C) 2001 Elsevier Science B.V. All rights reserved.

A numerical study of flexural buckling of foliated rock slopes

The occurrence of foliated rock masses is common in mining environment. Methods employing continuum approximation in describing the deformation of such rock masses possess a clear advantage over methods where each rock layer and each inter-layer interface (joint) is explicitly modelled. In devising such a continuum model it is imperative that moment (couple) stresses and internal rotations associated with the bending of the rock layers be properly incorporated in the model formulation. Such an approach will lead to a Cosserat-type theory. In the present model, the behaviour of the intact rock layer is assumed to be linearly elastic and the joints are assumed to be elastic-perfectly plastic. Condition of slip at the interfaces are determined by a Mohr-Coulomb criterion with tension cut off at zero normal stress. The theory is valid for large deformations. The model is incorporated into the finite element program AFENA and validated against an analytical solution of elementary buckling problems of a layered medium under gravity loading. A design chart suitable for assessing the stability of slopes in foliated rock masses against flexural buckling failure has been developed. The design chart is easy to use and provides a quick estimate of critical loading factors for slopes in foliated rock masses. It is shown that the model based on Euler's buckling theory as proposed by Cavers (Rock Mechanics and Rock Engineering 1981; 14:87-104) substantially overestimates the critical heights for a vertical slope and underestimates the same for sub-vertical slopes. Copyright (C) 2001 John Wiley & Sons, Ltd.

Physiological role of calcium-activated potassium currents in the rat lateral amygdala

Principal neurons in the lateral nucleus of the amygdala (LA) exhibit a continuum of firing properties in response to prolonged current injections ranging from those that accommodate fully to those that fire repetitively. In most cells, trains of action potentials are followed by a slow after hyperpolarization (AHP) lasting several seconds. Reducing calcium influx either by lowering concentrations of extracellular calcium or by applying nickel abolished the AHP, confirming it is mediated by calcium influx. Blockade of large conductance calcium-activated potassium channel (BK) channels with paxilline, iberiotoxin, or TEA revealed that BK channels are involved in action potential repolarization but only make a small contribution to the fast AHP that follows action potentials. The fast AHP was, however, markedly reduced by low concentrations of 4-aminopyridine and alpha-dendrotoxin, indicating the involvement of voltage-gated potassium channels in the fast AHP. The medium AHP was blocked by apamin and UCL1848, indicating it was mediated by small conductance calcium-activated potassium channel (SK) channels. Blockade of these channels had no effect on instantaneous firing. However, enhancement of the SK-mediated current by 1-ethyl-2-benzimidazolinone or paxilline increased the early interspike interval, showing that under physiological conditions activation of SK channels is insufficient to control firing frequency. The slow AHP, mediated by non-SK BK channels, was apamin-insensitive but was modulated by carbachol and noradrenaline. Tetanic stimulation of cholinergic afferents to the LA depressed the slow AHP and led to an increase in firing. These results show that BK, SK, and non-BK SK-mediated calcium-activated potassium currents are present in principal LA neurons and play distinct physiological roles.

Computer simulations of coupled problems in geological and geochemical systems

The finite element method is used to simulate coupled problems, which describe the related physical and chemical processes of ore body formation and mineralization, in geological and geochemical systems. The main purpose of this paper is to illustrate some simulation results for different types of modelling problems in pore-fluid saturated rock masses. The aims of the simulation results presented in this paper are: (1) getting a better understanding of the processes and mechanisms of ore body formation and mineralization in the upper crust of the Earth; (2) demonstrating the usefulness and applicability of the finite element method in dealing with a wide range of coupled problems in geological and geochemical systems; (3) qualitatively establishing a set of showcase problems, against which any numerical method and computer package can be reasonably validated. (C) 2002 Published by Elsevier Science B.V.

Channels underlying neuronal calcium-activated potassium currents

In many cell types rises in cytosolic calcium, either due to influx from the extracellular space, or by release from an intracellular store activates calcium dependent potassium currents on the plasmalemma. In neurons, these currents are largely activated following calcium influx via voltage gated calcium channels active during the action potentials. Three types of these currents are known: I-c. I-AHP and I-sAHP. These currents can be distinguished by clear differences in their pharmacology and kinetics. Activation of these potassium currents modulates action potential time course and the repetitive firing properties of neurons. Single channel studies have identified two types of calcium-activated potassium channel which can also be separated on biophysical and pharmacological grounds and have been named BK and SK channels. It is now clear that BK channels underlie Ic whereas SK channels underlie I-AHP. The identity of the channels underlying I-sAHP are not known. In this review, we discuss the properties of the different types of calcium-activated potassium channels and the relationship between these channels and the macroscopic currents present in neurons. (C) 2002 Elsevier Science Ltd. All rights reserved.

Calcium-activated potassium channels: Multiple contributions to neuronal function

Calcium-activated potassium channels are a large family of potassium channels that are found throughout the central nervous system and in many other cell types. These channels are activated by rises in cytosolic calcium largely in response to calcium influx via voltage-gated calcium channels that open during action potentials. Activation of these potassium channels is involved in the control of a number of physiological processes from the firing properties of neurons to the control of transmitter release. These channels form the target for modulation for a range of neurotransmitters and have been implicated in the pathogenesis of neurological and psychiatric disorders. Here the authors summarize the varieties of calcium-activated potassium channels present in central neurons and their defining molecular and biophysical properties.

Purification and Biochemical Properties of a Glucose-Stimulated beta-D-Glucosidase Produced by Humicola grisea var. thermoidea Grown on Sugarcane Bagasse

The effect of several carbon sources on the production of mycelial-bound beta-glucosidase by Humicola grisea var. thermoidea in submerged fermentation was investigated. Maximum production occurred when cellulose was present in the culture medium, but higher specific activities were achieved with cellobiose or sugarcane bagasse. Xylose or glucose (1%) in the reaction medium stimulated beta-glucosidase activity by about 2-fold in crude extracts from mycelia grown in sugarcane bagasse. The enzyme was purified by ammonium sulfate precipitation, followed by Sephadex G-200 and DEAE-cellulose chromatography, showing a single band in PAGE and SDS-PAGE. The beta-glucosidase had a carbohydrate content of 43% and showed apparent molecular masses of 57 and 60 kDa, as estimated by SDS-PAGE and gel filtration, respectively. The optimal pH and temperature were 6.0 and 50 degrees C, respectively. The purified enzyme was thermostable up to 60 min in water at 55 degrees C and showed half-lives of 7 and 14 min when incubated in the absence or presence of 50 mM glucose, respectively, at 60 degrees C. The enzyme hydrolyzed p-nitrophenyl-beta-D-glucopyranoside, p-nitrophenyl-beta-D-galactopyranoside, p-nitrophenyl-beta-D-fucopyranoside, p-nitrophenyl-beta-D-xylopyranoside, o-nitrophenyl-beta-D-galactopyranoside, lactose, and cellobiose. The best synthetic and natural substrates were p-nitrophenyl-beta-D-fucopyranoside and cellobiose, respectively. Purified enzyme activity was stimulated up to 2-fold by glucose or xylose at concentrations from 25 to 200 mM. The addition of purified or crude beta-glucosidase to a reaction medium containing Trichoderma reesei cellulases increased the saccharification of sugarcane bagasse by about 50%. These findings suggest that H. grisea var. thermoidea beta-glucosidase has a potential for biotechnological applications in the bioconversion of lignocellulosic materials.

Calcium Carbonate Particle Growth Depending on Coupling among Adjacent Layers in Hybrid LB/LbL Films

There are practical and academic situations that justify the study of calcium carbonate crystallization and especially of systems that are associated with organic matrices and a confined medium. Despite the fact that many different matrices have been studied, the use of well-behaved, thin organic films may provide new knowledge about this system. In this work, we have studied the growth of calcium carbonate particles on well-defined organic matrices that were formed by layer-by-layer (LbL) polyelectrolyte films deposited on phospholipid Langmuir-Blodgett films (LB). We were able to change the surface electrical charge density of the LB films by changing the proportions of a negatively charged lipid, the sodium salt of dimyristoyl-sn-glycero-phosphatidyl acid (DMPA), and a zwitterionic lipid. dimyristoyl-sn-glycero-phosphatidylethanolamine (DMPE). This affects the subsequent polyelectrolyte LbL film deposition, which also changes the the nature of the bonding (electrostatic interaction or hydrogen bonding). This approach allowed for the formation of calcium carbonate particles of different final shapes, roughnesses, and sizes. The masses of deposited lipids, polyelectrolytes, and calcium cabonate were quantified by the quartz crystal microbalance technique. The structures of obtained particles were analyzed by scanning electron microscopy.

Dissolved organic carbon in rainwater from areas heavily impacted by sugar cane burning

This work reports on rainwater dissolved organic carbon (DOC) from Ribeirao Preto (RP) and Araraquara over a period of 3 years. The economies of these two cities, located in Sao Paulo state (Brazil), are based on agriculture and related industries, and the region is strongly impacted by the burning of sugar cane foliage before harvesting. Highest DOC concentrations were obtained when air masses traversed sugar cane fields burned on the same day as the rain event. Significant increases in the DOC volume weighted means (VWM) during the harvest period, for both sites, and a good linear correlation (r=0.83) between DOC and K (a biomass burning marker) suggest that regional scale organic carbon emissions prevail over long-range transport. The DOC VWMs and standard deviations were 272 +/- 22 mu mol L-1 (n=193) and 338 +/- 40 mu mol L-1 (n=80) for RP and Araraquara, respectively, values which are at least two times higher than those reported for other regions influenced by biomass burning, such as the Amazon. These high DOC levels are discussed in terms of agricultural activities, particularly the large usage of biogenic fuels in Brazil, as well as the analytical method used in this work, which includes volatile organic carbon when reporting DOC values. Taking into account rainfall volume, estimated annual rainwater DOC fluxes for RP (4.8 g C m(-2) yr(-1)) and Araraquara (5.4 g C m(-2) yr(-1)) were close to that previously found for the Amazon region (4.8 g C m(-2) yr(-1)). This work also discusses whether previous calculations of the global rainwater carbon flux may have been underestimated, since they did not consider large inputs from biomass combustion sources, and suffered from a possible analytical bias. (c) 2008 Elsevier Ltd. All rights reserved.

Effect of early malnutrition and environmental stimulation in the performance of rats in the elevated plus maze

Malnourished rats since birth (mothers fed on 6% of protein) or controlled ones (16% of protein), half of each group received environmental stimulation (ES) from the age of 0-35th day, were studied. The performance in the elevated plus maze (EPM) was assessed on the last day. ES increased time spent and also the entries into open arms of EPM, but malnourished non-stimulated rats visited more segments near the central area than the distant ones. Data suggests an anxiolytic effect of ES which is less evident in malnourished rats. (C) 2009 Elsevier B.V. All rights reserved.

Neonatal exposure to LPS leads to heightened exploratory activity in adolescent rats

Although several reports have demonstrated physiological and behavioral changes in adult rats due to neonatal immune challenges, little is known about their effects in adolescence. Since neonatal exposure to lipopolysaccharide (LPS) alters the neural substrates involved in cognitive disorders, we tested the hypothesis that it may also alter the response to novel environments in adolescent rats. At 3 and 5 days of age, male Wistar rats received intraperitoneal injections of either vehicle solution or E. coli LPS (0.05 mg/kg) or were left undisturbed. In the mid-adolescent period, between 40 and 46 days of age, the rats were exposed to the following behavioral tests: elevated plus-maze, open-field, novel-object exploration task, hole-board and the modified Porsolt forced swim test. The results showed that, in comparison with control animals, LPS-treated rats exhibited (1) less anxiety-related behaviors and enhanced patterns of locomotion and rearing in the plus-maze and the open-field tests, (2) high levels of exploration of both objects in the novel-object task and of corner and central holes in hole-board test, and (3) more time spent diving, an active behavior in the forced swim test. The present findings suggest that neonatal LPS exposure has long-lasting effects on the behavior profile adolescent rats exhibit in response to novelty. This behavioral pattern, characterized by heightened exploratory activity in novel environments, also suggests that early immune stimulation may contribute to the development of impulsive behavior in adolescent rats. (C) 2010 Elsevier B.V. All rights reserved.

Cited2 is required both for heart morphogenesis and establishment of the left-right axis in mouse development

Establishment of the left-right axis is a fundamental process of vertebrate embryogenesis. Failure to develop left-right asymmetry leads to incorrect positioning and morphogenesis of numerous internal organs, and is proposed to underlie the etiology of several common cardiac malformations. The transcriptional modulator Cited2 is essential for embryonic development: Cited2-null embryos die during gestation with profound developmental abnormalities, including cardiac malformations, exencephaly and adrenal agenesis. Cited2 is also required for normal establishment of the left-right axis; we demonstrate that abnormal heart looping and right atrial and pulmonary isomerism are consistent features of the left-right-patterning defect. We show by gene expression analysis that Cited2 acts upstream of Nodal, Lefty2 and Pitx2 in the lateral mesoderm, and of Lefty1 in the presumptive floor plate. Although abnormal left-right patterning has a major impact on the cardiac phenotype in Cited2-null embryos, laterality defects are only observed in a proportion of these embryos. We have therefore used a combination of high-resolution imaging and three-dimensional (3D) modeling to systematically document the full spectrum of Cited2-associated cardiac defects. Previous studies have focused on the role of Cited2 in cardiac neural crest cell development, as Cited2 can bind the transcription factor Tfap2, and thus affect the expression of Erbb3 in neural crest cells. However, we have identified Cited2-associated cardiac defects that cannot be explained by laterality or neural crest abnormalities. In particular, muscular ventricular septal defects and reduced cell density in the atrioventricular (AV) endocardial cushions are evident in Cited2-null embryos. As we found that Cited2 expression tightly correlated with these sites, we believe that Cited2 plays a direct role in development of the AV canal and cardiac septa. We therefore propose that, in addition to the previously described reduction of cardiac neural crest cells, two other distinct mechanisms contribute to the spectrum of complex cardiac defects in Cited2-null mice; disruption of normal left-right patterning and direct loss of Cited2 expression in cardiac tissues.