Specificity of PCR and in situ hybridization assays designed for detection of Marteilia sydneyi and M-refringens

Primers and DNA probes designed for use in the specific detection of the paramyxean parasites Marteilia sydneyi and Marteilia refringens were tested for their potential to cross-react with closely related species in Polymerase Chain Reaction (PCR) and in situ hybridization. PCR primers and a DNA probe designed within the ITS1 rRNA of M. sydneyi were specific for M. sydneyi when compared with related species of Marteilia and Marteilioides. PCR primers designed within the 18S rRNA of M. refringens were specific in the detection of this species in PCR while a DNA probe (named Smart 2) designed on the same gene cross-reacted with M. sydneyi in tissue sections of Saccostrea glomerata as well as Marteilioides sp. infecting Striostrea mytiloides. Though not species specific, the Smart 2 probe provided a stronger signal in detection of all stages of M. sydneyi than the ITS1 probe. The ITS probe is proposed for use as a confirmatory diagnostic too] for M. sydneyi.

Comparative evaluation of juvenoids for control of cat fleas (Siphonaptera : Pulicidae) in topsoil

The efficacy of a photostable formulation of methoprene and two photostable juvenoids, fenoxycarb and pyriproxyfen, and their residual activity in inhibiting the emergence of adult cat fleas, Ctenocephalides felis (Bouche), was studied in topsoil. Nursery pots composed of clay, peat, and plastic, and wooden flats were used to hold soil samples. Treated soil samples were exposed to sunlight during the 63-d study period. Methoprene was as effective as fenoxycarb and pyriproxyfen against cat fleas for up to 42 d in clay, peat, and plastic pots at a concentration of 64.56 mg (AI) /m(2) (6 mg [AI] /ft(2)), but its activity declined significantly thereafter. In contrast, fenoxycarb and pyriproxyfen showed strong residual activity for the entire 63 d. The activity of methoprene declined even more rapidly over time in wooden flats, while at the same concentrations the other two juvenoids showed significant residual activity for 63 d. Clay, peat, and plastic pots were therefore considered to be equally effective for evaluating the outdoor efficacy of juvenoids in comparison to the wooden flats. However, results obtained with wooden flats may be more realistic when testing residual activity of volatile chemicals such as methoprene. Fenoxycarb and pyriproxyfen showed strong efficacy and residual activity at concentrations of 8.07, 16.14, and 32.28 mg (AI) /m(2), whereas methoprene did not cause a significant reduction of adult emergence at levels below 64.56 mg (AI) /m(2). LC50 values for methoprene, fenoxycarb, and pyriproxyfen needed for preventing flea emergence when applied to topsoil were estimated to be 0.643, 0.031, and 0.028 ppm, respectively.

In vivo and in vitro toxicities of pithraj and neem against rice green leafhopper (Nephotettix cincticeps Uhler)

Seed extracts of Aphanamixis polystachya Wall et Parker (pithraj) and Azadirachta indica A. Juss (neem) were evaluated for their in vivo and in vitro toxicity to Nephotettix cincticeps Uhler (rice green leafhopper). Crude extracts from both plants showed toxicity to leafhopper. Among them, the methanol extract of pithraj (MCX) was most toxic and showed 95% mortality effects at 72 h after treatment (HAT), followed by neem (74%). When LD50's were compared, it was found that the neem extract possessed the highest toxicity (LD50 16.59 μg/insect) at 72 HAT. Both the pithraj (MCX) and neem extracts showed their enzyme inhibition effectiveness against rice green leafhopper. The highest inhibition rate (IR) was caused by neem (60%) at the concentration of 2.0 mg/ml, followed by MCX (47%). The lowest IR50 value (0.97 mg/ml) was observed in neem at 30 min.

Monitorization of alveolar deposited surface area of nanoparticles and ultrafine particles in different environments

Nanotechnology is an important emerging industry with a projected annual market of around one trillion dollars by 2015. It involves the control of atoms and molecules to create new materials with a variety of useful functions. Although there are advantages on the utilization of these nano-scale materials, questions related with its impact over the environment and human health must be addressed too, so that potential risks can be limited at early stages of development. At this time, occupational health risks associated with manufacturing and use of nanoparticles are not yet clearly understood. However, workers may be exposed to nanoparticles through inhalation at levels that can greatly exceed ambient concentrations. Current workplace exposure limits are based on particle mass, but this criteria could not be adequate in this case as nanoparticles are characterized by very large surface area, which has been pointed out as the distinctive characteristic that could even turn out an inert substance into another substance exhibiting very different interactions with biological fluids and cells. Therefore, it seems that, when assessing human exposure based on the mass concentration of particles, which is widely adopted for particles over 1 μm, would not work in this particular case. In fact, nanoparticles have far more surface area for the equivalent mass of larger particles, which increases the chance they may react with body tissues. Thus, it has been claimed that surface area should be used for nanoparticle exposure and dosing. As a result, assessing exposure based on the measurement of particle surface area is of increasing interest. It is well known that lung deposition is the most efficient way for airborne particles to enter the body and cause adverse health effects. If nanoparticles can deposit in the lung and remain there, have an active surface chemistry and interact with the body, then, there is potential for exposure. It was showed that surface area plays an important role in the toxicity of nanoparticles and this is the metric that best correlates with particle-induced adverse health effects. The potential for adverse health effects seems to be directly proportional to particle surface area. The objective of the study is to identify and validate methods and tools for measuring nanoparticles during production, manipulation and use of nanomaterials.

Environmental determinants of infectious and parasitic diseases

A review of the role of the environment as a determinant of infectious and parasitic diseases is presented. Historical considerations and the several environmental classifications of diseases are introduced. In a broader perspective the subject is analyzed in view of the emergence of the environmental health area, with its new paradigms. A review of epidemiological studies about environmental sanitation conditions and measures is presented, analyzing the conclusions derived from 256 studies. Finally, an epidemiological study carried out in Betim, Minas Gerais is briefly described, in order to illustrate the potentiality of this kind of study. Setting priorities of interventions regarding diarrhea control was the aim of this investigation. Conclusion about the role of this approach to optimize preventive measures for the control of infectious and parasitic diseases, of sound importance to the reality of the developing world, is stated.

Combination of enteral and parenteral nutrition in intensive care patients: A new concept of optimization

Undernutrition is a widespread problem in intensive care unit and is associated with a worse clinical outcome. A state of negative energy balance increases stress catabolism and is associated with increased morbidity and mortality in ICU patients. Undernutrition-related increased morbidity is correlated with an increase in the length of hospital stay and health care costs. Enteral nutrition is the recommended feeding route in critically ill patients, but it is often insufficient to cover the nutritional needs. The initiation of supplemental parenteral nutrition, when enteral nutrition is insufficient, could optimize the nutritional therapy by preventing the onset of early energy deficiency, and thus, could allow to reduce morbidity, length of stay and costs, shorten recovery period and, finally, improve quality of life. (C) 2009 Elsevier Masson SAS. All rights reserved.

FGF receptors control vitamin D and phosphate homeostasis by mediating renal FGF-23 signaling and regulating FGF-23 expression in bone.

The functional interaction between fibroblast growth factor 23 (FGF-23) and Klotho in the control of vitamin D and phosphate homeostasis is manifested by the largely overlapping phenotypes of Fgf23- and Klotho-deficient mouse models. However, to date, targeted inactivation of FGF receptors (FGFRs) has not provided clear evidence for an analogous function of FGFRs in this process. Here, by means of pharmacologic inhibition of FGFRs, we demonstrate their involvement in renal FGF-23/Klotho signaling and elicit their role in the control of phosphate and vitamin D homeostasis. Specifically, FGFR loss of function counteracts renal FGF-23/Klotho signaling, leading to deregulation of Cyp27b1 and Cyp24a1 and the induction of hypervitaminosis D and hyperphosphatemia. In turn, this initiates a feedback response leading to high serum levels of FGF-23. Further, we show that FGFR inhibition blocks Fgf23 transcription in bone and that this is dominant over vitamin D-induced Fgf23 expression, ultimately impinging on systemic FGF-23 protein levels. Additionally, we identify Fgf23 as a specific target gene of FGF signaling in vitro. Thus, in line with Fgf23- and Klotho-deficient mouse models, our study illustrates the essential function of FGFRs in the regulation of vitamin D and phosphate levels. Further, we reveal FGFR signaling as a novel in vivo control mechanism for Fgf23 expression in bone, suggesting a dual function of FGFRs in the FGF-23/Klotho pathway leading to vitamin D and phosphate homeostasis.

Structure function relationships of ENaC and its role in sodium handling.

The epithelial sodium channel (ENaC) in the apical membrane of polarized epithelial cells is the rate-limiting step for Na entry into the cell; in series with the basolateral Na pump, it allows the vectorial transepithelial transport of Na ions. ENaC is expressed in different epithelia like the distal nephron or colon, and the airways epithelium. In the lung ENaC controls the composition and the amount of pulmonary fluid, whereas in the distal nephron ENaC under the control of aldosterone and vasopressin, is essential to adapt the amount of Na+ reabsorbed with the daily sodium intake. Activating mutations of ENaC cause severe disturbances of Na+ homeostasis leading to hypertension in human and in mouse models. Functional expression of ENaC in different cell systems allowed the identification of structural domains of the protein that are essential for channel function and/or modulation of channel activity. Site-directed mutations in specific domains of the channel protein lead to channel hyperactivity or channel loss of function. Knowledge about ENaC structure-function relationships opens new opportunities for development of pharmacological tools for controlling ENaC activity, such as channel activators of potential benefit in the treatment of pulmonary edema, or highly potent ENaC blockers with natriuretic effects.

Low-frequency transcranial magnetic stimulation over left dorsal premotor cortex improves the dynamic control of visuospatially cued actions.

Left rostral dorsal premotor cortex (rPMd) and supramarginal gyrus (SMG) have been implicated in the dynamic control of actions. In 12 right-handed healthy individuals, we applied 30 min of low-frequency (1 Hz) repetitive transcranial magnetic stimulation (rTMS) over left rPMd to investigate the involvement of left rPMd and SMG in the rapid adjustment of actions guided by visuospatial cues. After rTMS, subjects underwent functional magnetic resonance imaging while making spatially congruent button presses with the right or left index finger in response to a left- or right-sided target. Subjects were asked to covertly prepare motor responses as indicated by a directional cue presented 1 s before the target. On 20% of trials, the cue was invalid, requiring subjects to readjust their motor plan according to the target location. Compared with sham rTMS, real rTMS increased the number of correct responses in invalidly cued trials. After real rTMS, task-related activity of the stimulated left rPMd showed increased task-related coupling with activity in ipsilateral SMG and the adjacent anterior intraparietal area (AIP). Individuals who showed a stronger increase in left-hemispheric premotor-parietal connectivity also made fewer errors on invalidly cued trials after rTMS. The results suggest that rTMS over left rPMd improved the ability to dynamically adjust visuospatial response mapping by strengthening left-hemispheric connectivity between rPMd and the SMG-AIP region. These results support the notion that left rPMd and SMG-AIP contribute toward dynamic control of actions and demonstrate that low-frequency rTMS can enhance functional coupling between task-relevant brain regions and improve some aspects of motor performance.

Neuroendocrine control of body fluid homeostasis

Angiotensin II and atrial natriuretic peptide (ANP) play important and opposite roles in the control of water and salt intake, with angiotensin II promoting the intake of both and ANP inhibiting the intake of both. Following blood volume expansion, baroreceptor input to the brainstem induces the release of ANP within the hypothalamus that releases oxytocin (OT) that acts on its receptors in the heart to cause the release of ANP. ANP activates guanylyl cyclase that converts guanosine triphosphate into cyclic guanosine monophosphate (cGMP). cGMP activates protein kinase G that reduces heart rate and force of contraction, decreasing cardiac output. ANP acts similarly to induce vasodilation. The intrinsic OT system in the heart and vascular system augments the effects of circulating OT to cause a rapid reduction in effective circulating blood volume. Furthermore, natriuresis is rapidly induced by the action of ANP on its tubular guanylyl cyclase receptors, resulting in the production of cGMP that closes Na+ channels. The OT released by volume expansion also acts on its tubular receptors to activate nitric oxide synthase. The nitric oxide released activates guanylyl cyclase leading to the production of cGMP that also closes Na+ channels, thereby augmenting the natriuretic effect of ANP. The natriuresis induced by cGMP finally causes blood volume to return to normal. At the same time, the ANP released acts centrally to decrease water and salt intake.

Role of α2-adrenoceptors in the lateral parabrachial nucleus in the control of body fluid homeostasis

Central α2-adrenoceptors and the pontine lateral parabrachial nucleus (LPBN) are involved in the control of sodium and water intake. Bilateral injections of moxonidine (α2-adrenergic/imidazoline receptor agonist) or noradrenaline into the LPBN strongly increases 0.3 M NaCl intake induced by a combined treatment of furosemide plus captopril. Injection of moxonidine into the LPBN also increases hypertonic NaCl and water intake and reduces oxytocin secretion, urinary sodium, and water excreted by cell-dehydrated rats, causing a positive sodium and water balance, which suggests that moxonidine injected into the LPBN deactivates mechanisms that restrain body fluid volume expansion. Pretreatment with specific α2-adrenoceptor antagonists injected into the LPBN abolishes the behavioral and renal effects of moxonidine or noradrenaline injected into the same area, suggesting that these effects depend on activation of LPBN α2-adrenoceptors. In fluid-depleted rats, the palatability of sodium is reduced by ingestion of hypertonic NaCl, limiting intake. However, in rats treated with moxonidine injected into the LPBN, the NaCl palatability remains high, even after ingestion of significant amounts of 0.3 M NaCl. The changes in behavioral and renal responses produced by activation of α2-adrenoceptors in the LPBN are probably a consequence of reduction of oxytocin secretion and blockade of inhibitory signals that affect sodium palatability. In this review, a model is proposed to show how activation of α2-adrenoceptors in the LPBN may affect palatability and, consequently, ingestion of sodium as well as renal sodium excretion.

On logarithmic ratio quantities and their units

The use of special units for logarithmic ratio quantities is reviewed. The neper is used with a natural logarithm (logarithm to the base e) to express the logarithm of the amplitude ratio of two pure sinusoidal signals, particularly in the context of linear systems where it is desired to represent the gain or loss in amplitude of a single-frequency signal between the input and output. The bel, and its more commonly used submultiple, the decibel, are used with a decadic logarithm (logarithm to the base 10) to measure the ratio of two power-like quantities, such as a mean square signal or a mean square sound pressure in acoustics. Thus two distinctly different quantities are involved. In this review we define the quantities first, without reference to the units, as is standard practice in any system of quantities and units. We show that two different definitions of the quantity power level, or logarithmic power ratio, are possible. We show that this leads to two different interpretations for the meaning and numerical values of the units bel and decibel. We review the question of which of these alternative definitions is actually used, or is used by implication, by workers in the field. Finally, we discuss the relative advantages of the alternative definitions.

Gap junctions and connexin hemichannels in the regulation of haemostasis and thrombosis

Platelets are involved in the maintenance of haemostasis but their inappropriate activation leads to thrombosis, a principal trigger for heart attack and ischemic stroke. Although platelets circulate in isolation, upon activation they accumulate or aggregate together to form a thrombus, where they function in a coordinated manner to prevent loss of blood and control wound repair. Recent reports indicate that the stability and functions of a thrombus are maintained through sustained, contact dependent signalling between platelets. Given the role of gap junctions in the coordination of tissue responses, it was hypothesized that gap junctions may be present within a thrombus and mediate intercellular communication between platelets. Therefore studies were performed to explore the presence and functions of connexins in platelets. In this brief review, the roles of hemichannels and gap junctions in the control of thrombosis and haemostasis and the future directions for this research will be discussed.

ROLE OF CHOLINERGIC AND ADRENERGIC PATHWAYS OF THE MEDIAL SEPTAL AREA IN THE WATER-INTAKE AND PRESSOR-RESPONSE TO CENTRAL ANGIOTENSIN-II AND CARBACHOL IN RATS

In the present study, we investigated the effect of previous injection of either prazosin (alpha 1-adrenergic antagonist) or atropine (muscarinic cholinergic antagonist) into the medial septal area (MSA) on the presser and dipsogenic responses induced by intracerebroventricular (ICV) injection of carbachol (cholinergic agonist) and angiotensin II (ANGII) in rats. The presser and dipsogenic responses to ICV carbachol (7 nmol) were reduced after previous treatment of the MSA with atropine (0.5 to 5 nmol), but not prazosin (20 and 40 nmol). The dipsogenic response to ICV ANGII (25 ng) was reduced after prazosin (40 nmol) into the MSA. The presser response to ICV ANGII was not changed either by previous treatment of the MSA with prazosin or atropine. The present results suggest a dissociation among the pathways subserving the control of dipsogenic and presser responses to central cholinergic or angiotensinergic activation.

Optimal laser control of molecular photoassociation along with vibrational stabilization

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