Rat osseous plate alkaline phosphatase as Langmuir monolayer - An infrared study at the air-water interface

A glycosylphosphatidylinositol (GPI)-anchored enzyme (rat osseous plate alkaline phosphatase-OAP) was studied as monolayer (pure and mixed with lipids) at the air-water interface. Surface pressure and surface potential-area isotherms showed that the enzyme forms a stable monolayer and exhibits a liquid-expanded state even at surface pressure as high as 30 mN m(-1). Isotherms for mixed dimyristoylphosphatidic acid (DMPA)-OAP monolayer showed the absence of a liquid-expanded/liquid-condensed phase transition as observed for pure DMPA monolayer. In both cases, pure or mixed monolayer, the enzyme preserves its native conformation under compression at the air-water interface as observed from in situ p-polarized light Fourier transform-infrared reflection-absorption spectroscopic (FT-IRRAS) measurements. Changes in orientation and conformation of the enzyme due to the presence or absence of DMPA, as well as due to the surface compression, are discussed. (C) 2008 Published by Elsevier Inc.

Unusual Incorporation of Neutral and Low Water-Soluble Guest Molecules into Layered Double Hydroxides: The Case of Cucurbit [6 and 7]uril Inclusion Hosts

CNPq

Rare Earth Doped SnO(2) Nanoscaled Powders and Coatings: Enhanced Photoluminescence in Water and Waveguiding Properties

Luminescent Eu(3+) and Er(3+) doped SnO(2) powders have been prepared by Sn(4+) hydrolysis followed by a controlled growth reaction using a particle`s surface modifier in order to avoid particles aggregation. The powders so obtained doped with up to 2 mol% rare earth ions are fully redispersable in water at pH > 8 and present the cassiterite structure. Particles size range from 3 to 10 nm as determined by Photon Correlation Spectroscopy. Rare earth ions were found to be essentially incorporated into the cassiterite structure, substituting for Sn(4+), for doping concentration smaller than 0.05 mol%. For higher concentration they are also located at the particles surface. The presence of Eu(3+) ions at the surface of the particles hinder their growth and has therefore allowed the preparation of new materials consisting of water redispersable powders coated with Eu(3+)-beta dike-tonate complexes. Enhanced UV excited photoluminescence was observed in water. SnO(2) single layers with thickness up to 200 nm and multilayer coatings were spin coated on borosilicate glass substrates from the colloidal suspensions. Waveguiding properties were evaluated by the prism coupling technique. For a 0.3 mu m planar waveguide single propagating mode was observed with attenuation coefficient of 3.5 dB/cm at 632.8 nm.

Fluoxetine effect on kidney water reabsorption

Background. The pathogenesis of hyponatraemia caused by fluoxetine (Fx) use in the treatment of depression is not well understood. It has been attributed to a SIADH, although ADH-enhanced plasma level has not yet been demonstrated in all the cases reported in humans. This experiment aimed at investigating the effect of fluoxetine on the kidney and more specifically in the inner medullary collecting duct (IMCD). Methods. ( 1) In vivo study: ( a) 10 rats were injected daily i. p. with 10 mg/kg fluoxetine doses. After 10 days, rats were sacrificed and blood and kidneys were collected. (b) Immunoblotting studies for AQP2 protein expression in the IMCD from injected rats and in IMCD tubules suspension from 10 normal rats incubated with 10(-7) M fluoxetine. ( 2) In vitro microperfusion study: The osmotic water permeability (P-f, mu m/s) was determined in normal rats IMCD (n = 6), isolated and perfused by the standard methods. Results. In vivo study: ( a) Injected rats with fluoxetine lost about 12% body weight; Na+ plasma level decreased from 139.3 +/- 0.78 mEq/1 to 134.9 +/- 0.5 mEq/1 ( p < 0.01) and K+ and ADH plasma levels remained unchanged. ( b) Immunoblotting densitometric analysis of the assays showed an increase in AQP2 protein abundance of about 40%, both in IMCDs from injected rats [ control period (cont) 99.6 +/- 5.2 versus Fx 145.6 +/- 16.9, p < 0.05] and in tubule suspension incubated with fluoxetine ( cont 100.0 +/- 3.5 versus 143.0 +/- 2.0, p < 0.01). In vitro microperfusion study fluoxetine increased Pf in the IMCD in the absence of ADH from the cont 7.24 +/- 2.07 to Fx 15.77 +/- 3.25 ( p < 0.01). Conclusion. After fluoxetine use, the weight and plasma Na+ level decreased, and the K+ and ADH plasma levels remained unchanged, whereas the AQP2 protein abundance and water absorption in the IMCD increased, leading us to conclude that the direct effect of fluoxetine in the IMCD could explain at least in part, the hyponatraemia found sometime after this drug use in humans.

Carbamazepine can induce kidney water absorption by increasing aquaporin 2 expression

Background. Carbamazepine (Carba) is an anticonvulsant and psychotropic drug used widely for the treatment of intellectual disability and severe pains, but the incidence of hyponatremia is a common related occurrence. This hyponatremia is frequently attributed to a SIADH induced by this drug. It is also known that Carba is used to decrease the urinary volume in Diabetes Insipidus (DI) because it has an antidiuretic effect. Lithium (Li) is one of the most important drugs used to treat bipolar mood disorders. However Li has the undesirable capacity to induce DI. Nowadays, the association of these drugs is used in the treatment of patients with psychiatric and neurological problems. Methods. In vivo and in vitro (microperfusion) experiments were developed to investigate the effect of Carba in the rat Inner Medullary Collecting Duct (IMCD). Results. The results revealed that Carba was able to stimulate the V2 vasopressin receptor-Protein G complex increasing the water permeability (Pf) and water absorption. In vivo studies showed that in rats with lithium-induced DI, Carba decreased the urinary volume and increased the urinary osmolality. AQP2 expression was increased both in normal IMCD incubated with Carba and in IMCD from lithium-induced DI after Carba addition to the diet, when compared with the control. Conclusion. These results showed that the hyponatremia observed in patients using this anticonvulsant drug, at least in part, is due to the Carba capacity to increase IMCD`s Pf and that the Lithium-Carbamazepine association is beneficial to the patient.

Comparative Analysis of the Performance of Various Crystalloid Cardioplegic Solutions on Myocardial Protection After Prolonged Cold Ischemia

Introduction. The quality and effectiveness of myocardial protection are fundamental problems to expand the use of and consequently good outcomes of donated hearts for transplantation. Objective. The purpose of this investigation was to compare the cardioprotective effects of Krebs-Henseleit, Bretschneider-HTK, St Thomas, and Celsior solutions using a modified nonrecirculating Langendorff column model of isolated perfused rat heart during prolonged cold storage. Materials and Methods. After removal 36 rat hearts underwent isolated perfusion into a Langendorff apparatus using Krebs-Henseleit solution for a 15-minute period of recovery; we excluded organs that did not maintain an aortic pressure above 100 m Hg. Subsequently, we equally distributed the hearts into four groups according to the cardioprotection solution; group 1, Krebs-Henseleit (control); group II, Bretschneider-HTK; group III, St Thomas; and group IV, Celsior. Each heart received the specific cardioplegic solution at 10 C for 2-hour storage at 20 C, before a 15 minutes perfusion with Krebs-Henseleit solution for recovery and stabilization. After 60 additional minutes of perfusion, every 5 minutes we determined heart rate (HR), coronary flow (CF), left ventricular systolic pressure (LVSP), and positive and negative peak of the first derivative of left ventricular pressure (+dP/dt and dP/dt, respectively). Results. Comparative analysis by Turkey`s test showed the following performances among the groups at 60 minutes of reperfusion: HR: II = IV > III > I; CF: II = IV > I = III; LVSP: IV > I = II = III; +dP/dt: IV > I = II = III; and dP/dt: IV = II > I = II. Conclusion. Cardioprotective solutions generally used in clinical practice are not able to avoid hemodynamic alterations in hearts exposed to prolonged ischemia. Celsior solution showed better performance than Bretschneider-HTK, St Thomas, and Krebs-Henseleit.

Choroidal expansion during the water drinking test

To evaluate the correlation between intraocular pressure (IOP) rise, ocular pulse amplitude (OPA), and choroidal thickness (ChT) during the water drinking test (WDT). Primary open-angle glaucoma (POAG) patients were submitted to the WDT followed by serial IOP measurements using dynamic contour tonometry (DCT), Goldman tonometry (GAT), and ChT measurements using ultrasonographic A and B-scan (USG). A control group not submitted to the test was also evaluated using DCT, GAT, and USG. Intraclass correlation coefficient (ICC) was calculated in the control group in order to assess the reproducibility of measurements. Spearman`s coefficient (rho) was used to assess the correlation between the variables. Thirty eyes were included in the study. There was a significant IOP rise during the WDT using both GAT and DCT (p < 0.001). The OPA and ChT measurements also increased significantly (p < 0.001). Spearman`s correlation between the OPA values and ChT measurements was significant and moderate (rho = 0.40, p = 0.005). The average increase of OPA and ChT measurements occurred 15 min before the IOP rise. There was a significant increase of OPA and ChT measurements followed by an IOP rise during the WDT. Increased choroidal volume due to hemodynamic forces may be enrolled in the mechanism of IOP elevation during this stress test.

Centella asiatica water extract inhibits iPLA(2) and cPLA(2) activities in rat cerebellum

Centella asiatica (L.) Urb an is distributed widely in South America and Asia and is known as a therapeutic agent in folk medicine, capable of improving memory and treating several neurological disorders. Asiaticoside is one of the compounds found in C asiatica leaves that is suggested to be responsible for its pharmacological potential. Phospholipase A(2) (PLA(2)) is a group of enzymes that has abnormal activity in the central nervous system in some neuropsychiatric diseases. In this work, the asiaticoside present in C asiatica water extract was quantified by HPLC analysis. We also evaluated the activity of subtypes of PLA(2) in cerebellar samples from rats after C asiatica water extract treatment using a radioenzymatic assay. Asiaticoside was the major compound (84%) found in Centella water extract. We found a dose-dependent inhibitory effect of C asiatica water extract on the activity of Ca(2+)-independent PLA(2) (iPLA(2)) and cytosolic PLA(2) (cPLA(2)). The inhibition of these enzymes in the brain suggests that C asiatica may be useful to treat conditions associated with increased PLA(2) activity in the brain, such as epilepsy, stroke, multiple sclerosis and other neuropsychiatric disorders. (C) 2008 Elsevier GmbH. All rights reserved.

Water deficit and ABA application on leaf gas exchange and flavonoid content in marigold (Calendula officinalis L.)

Water deficit and ABA application on leaf gas exchange and flavonoid content in marigold (Calendula officinalis L.).The goal of this study was to evaluate the effects of water deficit and abscisic acid (ABA) application on physiological parameters and flavonoid production in marigold plant. The experiment was performed under nursery conditions with potted plants. It was tested water deficit by withholding water (control - diary irrigation, 3, 6 and 9 days without irrigation) followed by 3 ABA concentrations (0, 10 e 100 mu M) applied in the beginning of blooming. It was evaluated the relative water content and the leaf gas exchange using a portable infrared gas analyzer (A: net photosynthesis, gs: stomatal conductance, E: transpiration, Ci: CO(2) intercellular concentration and EUA: water use efficiency). At the end of 9 days of water deficit there were significant decreases in all the characteristics evaluated, independent of ABA application. This suggests that the main effect of ABA was to cause a reduction on gs which was accompanied of a reduction in A, only when the plants were submitted to the water deficit. There was no significant difference among the levels of water deficit tested in relation to the total flavonoid content in inflorescences. However, ABA restricted the flavonoids biosynthesis both in control plant and stressed plants.

Effects of Cold Stress, Corticosterone and Catecholamines on Phagocytosis in Mice: Differences between Resting and Activated Macrophages

Objective: We subjected mice to acute cold stress and studied the effect on phagocytosis by peritoneal macrophages mediated by 3 types of phagocytic receptors: Fc gamma, complement receptors 3 (CR3) and mannose and beta-glucan receptors. Methods: Mice were subjected to a cold stress condition (4 C for 4 h), and then peritoneal macrophages were harvested and phagocytosis assays performed in vitro. Results: We found a striking difference between resting and lipopolysaccharide (LPS)-activated macrophages (by intraperitoneal injection of LPS 4 days before the stress experiment): for resting macrophages cold stress caused a decrease in phagocytosis mediated by Fc gamma or mannose receptors, while for activated macrophages we observed an increase in phagocytosis by the 3 types of receptors. These effects were associated with an increase in plasma concentrations of corticosterone and catecholamines following the cold stress. In order to verify whether these hormone changes could account for the observed effects on phagocytosis, we performed in vitro assays by incubating macrophages harvested from nonstressed animals with these hormones for 4 h at 37 degrees C and measuring their phagocytic capacity. The following experiments were done: (a) with resting (nonactivated) macrophages; (b) with macrophages previously activated in vitro by incubation with LPS; (c) with macrophages previously activated in vivo by intraperitoneal injection of mice with LPS, 4 days before harvesting the cells. We found that for resting macrophages, corticosterone decreased phagocytosis mediated by Fc gamma and mannose and beta-glucan receptors, but catecholamines had no effect. For macrophages activated either in vivo or in vitro, catecholamines caused an increase in phagocytosis (excluding mannose receptors) while corticosterone had no effect. Conclusion: The above findings suggest that stress can regulate phagocytosis in different ways, depending on the kind of phagocytic receptor involved, the level of stress hormones and the physiological state of the macrophages. Copyright (C) 2010 S. Karger AG, Basel

Effects of Acute Cold Stress on Phagocytosis of Apoptotic Cells: The Role of Corticosterone

Background and Aims: Stress can alter many aspects of the immune response, and many studies have been conducted on the effects of stress on inflammatory processes, but little is known about its influence on the resolution of inflammation in tissue homeostasis, which includes the clearance of apoptotic cells by macrophages in a non-phlogistic way. In the present study, we investigated the effect of acute cold stress on the phagocytosis of apoptotic cells by macrophages. Methods: Mice were submitted to acute cold stress (4 degrees C for 4 h) and the capacity of peritoneal macrophages to phagocyte apoptotic thymocytes and to secrete anti-inflammatory cytokines was evaluated. Plasma corticosterone and catecholamine levels were investigated to assess their effect on the phagocytic capacity of macrophages in vitro. Results: We showed that acute cold stress decreases phagocytosis of apoptotic cells at the inflammatory site by lipopolysaccharide-activated macrophages but did not affect resting macrophages. The inhibitory effect on phagocytosis is accompanied by a reduced level of TGF-beta and higher IL-10 secretion. After stress, plasma concentrations of corticosterone increased 6-fold, epinephrine 2-fold and norepinephrine 1.7-fold compared to control mice. In vitro experiments showed that the decrease in phagocytosis after stress could be attributed, at least in part, to the effects of corticosterone; epinephrine and norepinephrine had no effect. Conclusions: The current study shows that acute cold stress decreases phagocytosis of apoptotic cells from an inflammatory environment by macrophages, and this inhibition is mediated by the intracellular glucocorticoid receptor. Copyright (C) 2009 S. Karger AG, Basel

Characteristics of women who frequently under report their energy intake: a doubly labelled water study

Background/Objectives: We applied three dietary assessment methods and aimed at obtaining a set of physical, social and psychological variables that can discriminate those individuals who did not underreport (`never under-reporters`), those who underreported in one dietary assessment method (`occasional under-reporters`) and those who underreported in two or three dietary assessment methods (`frequent under-reporters`). Participants/Methods: Sixty-five women aged 18-57 years were recruited for this study. Total energy expenditure was determined by doubly labelled water, and energy intake was estimated by three 24-h diet recalls, 3-day food records and a food frequency questionnaire. A multiple discriminant analysis was used to identify which of those variables better discriminated the three groups: body mass index (BMI), income, education, social desirability, nutritional knowledge, dietary restraint, physical activity practice, body dissatisfaction and binge-eating symptoms. Results: Twenty-three participants were `never under-reporters`. Twenty-four participants were `occasional under-reporters` and 18 were `frequent under-reporters`. Four variables entered the discriminant model: income, BMI, social desirability and body dissatisfaction. According to potency indices, income contributed the most to the total discriminant power, followed in decreasing order by social desirability score, BMI and body dissatisfaction. Income, social desirability and BMI were the characteristics that mainly separated the `never under-reporters` from the under-reporters (occasional or frequent). Body dissatisfaction better discriminated the `occasional under-reporters` from the `frequent under-reporters`. Conclusions: `Frequent under-reporters` have a greater BMI, social desirability score, body dissatisfaction score and lower income. These four variables seemed to be able to discriminate individuals who are more prone to systematic under reporting. European Journal of Clinical Nutrition (2009) 63, 1192-1199; doi:10.1038/ejcn.2009.54; published online 15 July 2009

Water excitation MPRAGE: An alternative sequence for postcontrast imaging of the abdomen in noncooperative patients at 1.5 Tesla and 3.0 Tesla MRI

Purpose: To evaluate the diagnostic image quality of post-gadolinium water excitation-magnetization-prepared rapid gradient-echo (WE-MPRAGE) sequence in abdominal examinations of noncooperative patients at 1.5 Tesla (T) and 3.0T MRI. Materials and Methods: Eighty-nine consecutive patients (48 males and 41 females; mean age +/- standard deviation, 54.6 +/- 16.6 years) who had MRI examinations including postgadolinium WE-MPRAGE were included in the study. Of 89 patients, 33 underwent noncooperative protocol at 1.5T. 10 under-went noncooperative protocol at 3.0T, and 46 underwent cooperative protocol at 3.0T. Postgadolinium WE-MPRAGE, MPRAGE, and three-dimensional gradient-echo sequences of these three different groups were qualitatively evaluated for image quality, extent of artifacts, lesion conspicuity, and homogeneity of fat-attenuation by two reviewers retrospectively, independently, and blindly. The results were compared using Wilcoxon signed rank and Mann-Whitney U tests. Kappa statistics were used to measure the extent of agreement between the reviewers. Results: The average scores indicated that the images were diagnostic for WE-MPRAGE at 1.5T and 3.0T in noncooperative patients. WE-MPRAGE achieved homogenous fat-attenuation in 31/33 (94%) of noncooperative patients at 1.5T and 10/10 (100%) of noncooperative patients at 3.0T. WE-MPRAGE at 3.0T had better results for image quality, extent of artifacts, lesion conspicuity and homogeneity of fat-attenuation compared with WE-MPRAGE at 1.5T. in noncooperative patients (P = 0.0008, 0.0006, 0.0024, and 0.0042: respectively). Kappa statistics varied between 0.76 and 1.00, representing good to excellent agreement. Conclusion: WE-MPRAGE may be used as a T1-weighted postgadolinium fat-attenuated sequence in noncooperative patients, particularly at 3.0T MRI.

Under-reporting of food intake is frequent among Brazilian free-living older persons: a doubly labelled water study

The assessment of food intake is essential for the development of dietetic interventions. Accuracy is low when intake is assessed by questionnaires, the under-reporting of food intake being frequent. Most such studies, however, were performed in developed countries and there is little data about the older population of developing nations. This study aimed to verify the total energy expenditure (TEE) of independent older Brazilians living in an urban area, through the doubly labelled water (DLW) method and to compare it with the reported energy intake obtained through the application of a food frequency questionnaire (FFQ). Initially, 100 volunteers aged from 60 to 75 years had their body composition determined by dual-energy X-ray absorptiometry (DEXA). Five volunteers of each quartile of body fat percentage had their energy expenditure determined by DLW. The mean age of the subjects included in this phase of the study was 66.4 +/- 3.5 years, and ten of the subjects were men. The mean TEE was 2565 +/- 614 and 2154 +/- 339 kcal.day(-1) for men and women, respectively. The Physical Activity Level (PAL) was 1.58 +/- 0.31 and 1.52 +/- 0.22, respectively. Under-reporting of food intake was highly prevalent, with a mean percentage of reported intake in relation to measured TEE of -17.7%. Thus, under-reporting of food intake is highly prevalent among Brazilian independent older persons. The DLW method is an important tool in nutritional studies and its use is to be recommended in developing countries. Copyright (C) 2010 John Wiley & Sons, Ltd.

Water deprivation increases Fos expression in hypothalamic corticotropin-releasing factor neurons induced by right atrial distension in awake rats

Atrial mechanoreceptors, sensitive to stretch, contribute in regulating heart rate and intravascular volume. The information from those receptors reaches the nucleus tractus solitarius and then the paraventricular nucleus (PVN), known to have a crucial role in the regulation of cardiovascular function. Neurons in the PVN synthesize CRF, AVP, and oxytocin (OT). Stimulation of atrial mechanoreceptors was performed in awake rats implanted with a balloon at the junction of the superior vena cava and right atrium. Plasma ACTH, AVP, and OT concentrations and Fos, CRF, AVP, and OT immunolabeling in the PVN were determined after balloon inflation in hydrated and water-deprived rats. The distension of the balloon increased the plasma ACTH concentrations, which were higher in water-deprived than in hydrated rats (P < 0.05). In addition, the distension in the water-deprived group decreased plasma AVP concentrations (P < 0.05), compared with the respective control group. The distension increased the number of Fos- and double-labeled Fos/CRF neurons in the parvocellular PVN, which was higher in the water-deprived than in the hydrated group (P < 0.01). There was no difference in the Fos expression in magnocellular PVN neurons after distension in hydrated and water-deprived groups, compared with respective controls. In conclusion, parvocellular CRF neurons showed an increase of Fos expression induced by stimulation of right atrial mechanoreceptors, suggesting that CRF participates in the cardiovascular reflex adjustments elicited by volume loading. Activation of CRF neurons in the PVN by cardiovascular reflex is affected by osmotic stimulation.