Role of catecholaminergic neurones of the caudal ventrolateral medulla in cardiovascular responses induced by acute changes in circulating volume in rats

Several findings suggest that catecholaminergic neurones in the caudal ventrolateral medulla (CVLM) contribute to body fluid homeostasis and cardiovascular regulation. The present study sought to determine the effects of lesions of these neurones on the cardiovascular responses induced by changes in circulating volume. All experiments were performed in male Wistar rats (320-360 g). Medullary catecholaminergic neurones were lesioned by microinjection of anti-dopamine beta-hydroxylase-saporin (6.3 ng in 60 nl; SAP rats, n = 14) into the CVLM, whereas sham rats received microinjections of free saporin (1.3 ng in 60 nl, n = 15). Two weeks later, rats were anaesthetized (urethane, 1.2 g kg(-1), I.V..), instrumented for measurement of mean arterial pressure (MAP), renal blood flow (RBF) and renal vascular conductance (RVC), and infused with hypertonic saline (HS; 3 M NaCl, 0.18 ml (100 g body weight)(-1), I.V.) or an isotonic solution (volume expansion, VE; 4% Ficoll, 1% of body weight, I.V.). In sham rats, HS induced sustained increases in RBF and RVC (155 +/- 7 and 145 +/- 6% of baseline, at 20 min after HS). In SAP rats, RBF responses to HS were blunted (125 +/- 6%) and RVC increases were abolished (108 +/- 5%) 20 min after HS. Isotonic solution increased RBF and RVC in sham rats (149 +/- 10 and 145 +/- 12% of baseline, respectively, at 20 min). These responses were reduced in SAP rats (131 +/- 6 and 126 +/- 5%, respectively, at 20 min). Pressor responses to HS were larger in SAP rats than in sham rats (17 +/- 5 versus 9 +/- 2 mmHg, at 20 min), whereas during VE these responses were similar in both groups (6 +/- 3 versus 4 +/- 6 mmHg, at 20 min). Immunohistochemical analysis indicates that microinjections of anti-D beta H-saporin produced extensive destruction within the A1/C1 cell groups in the CVLM. These results suggest that catecholaminergic neurones mediate the cardiovascular responses to VE or increases in plasma sodium levels.

Holographic recording in [Sb(Po-3)(3)](n)-Sb2O3 glassy films by photoinduced volume and refraction index changes

Glassy films of 0.2[Sb(PO3)(3)]-0,8Sb(2)O(3) with 0.8 mum-thickness were deposited on quartz substrates by electron beam evaporation. A contraction in the film thickness (photoinduced decrease in volume) and photobleaching effect associated with a decrease of up to 25% in the index of refraction has been observed in the films after irradiation near the bandgap (3.89 eV), using the 350.7 nm (3.54 eV) Kr+ ion laser line with 2.5 W/cm(2) for 30 min. A loss of 30% in the phosphorus concentration was measured by wavelength dispersive X-ray microanalysis in the film after laser irradiation with 5.0 W/cm(2) for 1.0 h. These photoinduced changes in the samples are dependent on the power density and intensity profile of the laser beam. Using a Lloyd's mirror setup for continuous wave holography it was possible to record holographic gratings with period from 500 nm up to 20 mum and depth profile of similar to50 nm in the films after laser irradiation with 5.0 W/cm(2) for 1 h. Real-time diffraction efficiency measurements have shown that ultraviolet irradiation induces first a refractive index grating formation, and after this, the photocon traction effect takes place generating an irreversible relief grating. Diffraction efficiency up to 10% was achieved for the recorded gratings. 3D-refraction index measurements and atomic force microscopy images are presented. (C) 2004 Elsevier B.V. All rights reserved.

Hematologic changes in propofol-anesthetized dogs with or without tramadol administration

Drugs commonly used in anesthesia practice may significantly alter the oxidative state of blood cells. This mechanism could contribute to the immune suppression that occurs transiently in the early postoperative period. Thus, we assessed the effects of continuous rate infusion (CRI) of propofol associated or not with tramadol on hematologic parameters in dogs. Eight adult mongrel dogs were anesthetized on 2 occasions, 15 d apart. Two groups were formed: control group (CG) and tramadol group (GT). Propofol was used for induction (10mg kg-1) followed by a CRI (0.7mg kg-1minute-1). The animals were positioned in lateral recumbency and mechanically ventilated with inspired oxygen fraction of 0.6. In TG, tramadol (2mg kg-1) followed by a CRI (0.5mg kg-1minute-1) was administered in dogs. In the CG the sodium chloride (NaCl) solution at 0.9% was administered followed by its CRI, in the same volume that was used in TG. The measurement was taken before anesthesia induction (Tbasal), 30 minutes after induction (T0) and then at 30-minute intervals (T30 to T60). Red blood cells, hematocrit, hemoblogin concentration and total leukocytes count decreased from T0 in both groups. In TG, lymphocytes count at Tbasal [1.86 (0.82) x103µl-1] was greater than at T0, T30 and T60 [0.96(0.50), 0.92(0.48) and 0.95(0.48) x103µl-1, respectively]. No significant differences were observed for platelets neutrophil, eosinophil, basophil and monocyte count. In dogs, propofol-anesthesia associated or not with tramadol promoted decrease in blood cell count and should be used with caution in immunossupressed patients.

Effects of dexmedetomidine on pulse pressure variation changes induced by hemorrhage followed by volume replacement in isoflurane-anesthetized dogs

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Effects of high and low volume of strength training on muscle strength, muscle volume and lipid profile in postmenopausal women

Changes in lipid profile are considered a risk factor for cardiovascular disease (CVD), especially in postmenopausal woman who have been associated with age-related loss of muscle mass. The beneficial role of aerobic exercise in the prevention of CVD has been well documented. However, the effect of strength training has not been established. The purpose of this study was to determine the changes of lipoprotein levels after 12 weeks of different volumes of strength training and its correlation with strength and muscle volume in postmenopausal women. The participants were randomized into three groups: low volume (LVST; n = 12, 1 set) and high volume of strength training (HVST; n = 11, 3 sets), or control group (n = 12). Training groups performed 12 weeks of supervised strength exercises, 15 maximum repetitions, five times a week, 20 minutes for LVST and 40 minutes for HVST for each training session. Measurements included body composition, strength and muscle volume, as well as blood analysis (glucose, total cholesterol, triglycerides, low-density lipoprotein, and high-density lipoprotein) pre- and post-training. The HVST and LVST improved the one-repetition maximum knee extension strength (p < 0.001), maximal dynamic strength (p < 0.001), and muscle volume (p = 0.048). Post-training triglyceride was lower in HVST when compared to LVST and the control group (p = 0.047). Even though they present the same neuromuscular and morphological adaptations in postmenopausal women, the HVST is more effective than LVST in improving the lipid profile of postmenopausal woman, and can be considered as an ideal program of intervention to reverse changes in lipid metabolism commonly found in this group. Copyright (C) 2014, The Society of Chinese Scholars on Exercise Physiology and Fitness. Published by Elsevier (Singapore) Pte Ltd. All rights reserved.

Cannabinoid CB1 receptor mediates glucocorticoid effects on hormone secretion induced by volume and osmotic changes

1. The present study provides the first in vivo evidence that the cannabinoid CB1 receptor mediates the effects of dexamethasone on hormone release induced by changes in circulating volume and osmolality. Male adult rats were administered with the CB1 receptor antagonist rimonabant (10 mg/Kg, p.o.), followed or not in 1 hour by dexamethasone (1 mg/Kg, i.p.). Extracellular volume expansion (EVE, 2 mL/100 g of body weight, i.v.) was performed 2 hours after dexamethasone or vehicle treatment using either isotonic (I-EVE, 0.15 mol/L) or hypertonic (H-EVE, 0.30 mol/L) NaCl solution. Five minutes after EVE, animals were decapitated and trunk blood was collected for all plasma measurements. 2. Rimonabant potentiated oxytocin (OT) secretion induced by H-EVE and completely reversed the inhibitory effects of dexamethasone in response to the same stimulus. These data suggest that glucocorticoid modulation of OT release is mediated by the CB1 receptor. 3. Although dexamethasone did not affect vasopressin (AVP) secretion induced by H-EVE, the administration of rimonabant potentiated AVP release in response to the same stimulus, supporting the hypothesis that the CB1 receptor regulates AVP secretion independently of glucocorticoid-mediated signalling. 4. Dexamethasone alone did not affect atrial natriuretic peptide (ANP) release stimulated by I-EVE or H-EVE. However, pretreatment with rimonabant potentiated ANP secretion induced by H-EVE, suggesting a possible role for the CB1 receptor in the control of peripheral factors that modulate cardiovascular function. 5. Rimonabant also reversed the inhibitory effects of dexamethasone on H-EVE-induced corticosterone secretion, reinforcing the hypothesis that the CB1 receptor may be involved in the negative feedback exerted by glucocorticoids on the activity of the hypothalamicpituitaryadrenal axis. 6. Collectively, the results of the present study indicate that the CB1 receptor modulates neurohypophyseal hormone secretion and systemic factors, such as corticosterone and ANP, thus participating in homeostatic responses to altered extracellular volume and plasma tonicity.

Changes in the volume and density of calvarial split bone grafts after alveolar ridge augmentation

OBJECTIVES: One main problem occurring after bone grafting is resorption, leading to insufficient bone volume and quality, and may subsequently cause dental implant failure. Comparison of graft volume and bone density of iliac crest and calvarial transplants determined by animal studies demonstrates significantly lower resorption of bone grafts harvested from the skull. This paper is the first clinical study evaluating bone volume and density changes of calvarial split bone grafts after alveolar ridge reconstruction. MATERIAL AND METHODS: Bone volume and density were determined using CT scans and the software program Dicom Works in a total of 51 calvarial grafts after alveolar ridge augmentation in 15 patients. CT scans were taken in all 15 patients immediately after grafting (T0) and before implantation after a postoperative period of 6 months (T1). In five patients (26 calvarial grafts), a 1-year follow-up was performed (T2). RESULTS: A mean volume reduction of 16.2% at T1 (15 patients) and 19.2% at T2 (five patients) was observed. Bone density was high--about 1000 Hounsfield units--and did not change during the 1-year period. At the time of implantation, 41 transplants were classified as quality 1 bone and 10 as quality 2-3 bone. Grafting area and the technique used for grafting (inlay or onlay graft) did not affect the postoperative bone volume reduction. Generalized osteoporosis did not increase the resorption rate of calvarial transplants. CONCLUSION: Based on these findings, calvarial split bone grafts are a promising alternative for alveolar ridge reconstruction in dental implantology.

Deficiency in parvalbumin, but not in calbindin D-28k upregulates mitochondrial volume and decreases smooth endoplasmic reticulum surface selectively in a peripheral, subplasmalemmal region in the soma of Purkinje cells

The Ca(2+)-binding proteins parvalbumin (PV) and calbindin D-28k (CB) are key players in the intracellular Ca(2+)-buffering in specific cells including neurons and have profound effects on spatiotemporal aspects of Ca(2+) transients. The previously observed increase in mitochondrial volume density in fast-twitch muscle of PV-/- mice is viewed as a specific compensation mechanism to maintain Ca(2+) homeostasis. Since cerebellar Purkinje cells (PC) are characterized by high expression levels of the Ca(2+) buffers PV and CB, the question was raised, whether homeostatic mechanisms are induced in PC lacking these buffers. Mitochondrial volume density, i.e. relative mitochondrial mass was increased by 40% in the soma of PV-/- PC. Upregulation of mitochondrial volume density was not homogenous throughout the soma, but was selectively restricted to a peripheral region of 1.5 microm width underneath the plasma membrane. Accompanied was a decreased surface of subplasmalemmal smooth endoplasmic reticulum (sPL-sER) in a shell of 0.5 microm thickness underneath the plasma membrane. These alterations were specific for the absence of the "slow-onset" buffer PV, since in CB-/- mice neither changes in peripheral mitochondria nor in sPL-sER were observed. This implicates that the morphological alterations are aimed to specifically substitute the function of the slow buffer PV. We propose a novel concept that homeostatic mechanisms of components involved in Ca(2+) homeostasis do not always occur at the level of similar or closely related molecules. Rather the cell attempts to restore spatiotemporal aspects of Ca(2+) signals prevailing in the undisturbed (wildtype) situation by subtly fine tuning existing components involved in the regulation of Ca(2+) fluxes.

Phosphoregulation of K(+)-Cl(-) cotransporter 4 during changes in intracellular Cl(-) and cell volume

It has long been stated that the K(+)-Cl(-) cotransporters (KCCs) are activated during cell swelling through dephosphorylation of their cytoplasmic domains by a protein phosphatase (PP) but that other enzymes are involved by targeting this PP or the KCCs directly. To date, however, the role of signaling intermediates in KCC regulation has been deduced from indirect evidence rather than in vitro phosphorylation studies, and examined after simulation of ion transport through cell swelling or N-ethylmaleimide treatment. In this study, the oocyte expression system was used to examine the effects of changes in cell volume (C(VOL)) and intracellular [Cl(-)] ([Cl(-)](i)) on the activity and phosphorylation levels (P(LEV)) of KCC4, and determine whether these effects are mediated by PP1 or phorbol myristate acetate (PMA)-sensitive effectors. We found that (1) low [Cl(-)](i) or low C(VOL) leads to decreased activity but increased P(LEV), (2) high C(VOL) leads to increased activity but no decrease in P(LEV) and (3) calyculin A (Cal A) or PMA treatment leads to decreased activity but no increase in P(LEV). Thus, we have shown for the first time that one of the KCCs can be regulated through direct phosphorylation, that changes in [Cl(-)](i) or C(VOL) modify the activity of signaling enzymes at carrier sites, and that the effectors directly involved do not include a Cal A-sensitive PP in contrast to the widely held view. J. Cell. Physiol. 219: 787-796, 2009. (c) 2009 Wiley-Liss, Inc.

Estimate of the total volume of Svalbard glaciers, and their potential contribution to sea-level rise, using new regionally based scaling relationships

We present a set of new volume scaling relationships specific to Svalbard glaciers, derived from a sample of 60 volume–area pairs. Glacier volumes are computed from ground-penetrating radar (GPR)-retrieved ice thickness measurements, which have been compiled from different sources for this study. The most precise scaling models, in terms of lowest cross-validation errors, are obtained using a multivariate approach where, in addition to glacier area, glacier length and elevation range are also used as predictors. Using this multivariate scaling approach, together with the Randolph Glacier Inventory V3.2 for Svalbard and Jan Mayen, we obtain a regional volume estimate of 6700 ± 835 km3, or 17 ± 2 mm of sea-level equivalent (SLE). This result lies in the mid- to low range of recently published estimates, which show values as varied as 13 and 24 mm SLE. We assess the sensitivity of the scaling exponents to glacier characteristics such as size, aspect ratio and average slope, and find that the volume of steep-slope and cirque-type glaciers is not very sensitive to changes in glacier area.

Changes in brain cell shape create residual extracellular space volume and explain tortuosity behavior during osmotic challenge

Diffusion of molecules in brain extracellular space is constrained by two macroscopic parameters, tortuosity factor λ and volume fraction α. Recent studies in brain slices show that when osmolarity is reduced, λ increases while α decreases. In contrast, with increased osmolarity, α increases, but λ attains a plateau. Using homogenization theory and a variety of lattice models, we found that the plateau behavior of λ can be explained if the shape of brain cells changes nonuniformly during the shrinking or swelling induced by osmotic challenge. The nonuniform cellular shrinkage creates residual extracellular space that temporarily traps diffusing molecules, thus impeding the macroscopic diffusion. The paper also discusses the definition of tortuosity and its independence of the measurement frame of reference.

Folate supplementation fails to affect vascular function and carotid artery intima media thickness in cyclosporin A-treated renal transplant recipients

Background: Cyclosporin A (CsA)-treated renal transplant recipients (RTR) exhibit relative hyperhomocystinemia and vascular dysfunction. Folate supplementation lowers homocysteine and has been shown to improve vascular function in healthy subjects and patients with coronary artery disease. The aim of this study was to assess the effects of 3 months of folate supplementation (5 mg/day) on vascular function and structure in RTR. Methods: A double-blind, placebo-controlled crossover study was conducted in 10 CsA-treated RTR. Vascular structure was measured as carotid artery intima media thickness (IMT) and function was assessed as changes in brachial artery diameter during reactive hyperemia (RE) and in response to glyceryl trinitrate (GTN). Function data were analyzed as absolute and percent change from baseline and area under the diameter/time curve. Blood samples were collected before and after supplementation and analyzed for total plasma homocysteine, folate, vitamin B-12 and asymmetric dimethyl arginine (ADMA) in addition to regular measures of hemoglobin, hematocrit, mean corpuscular volume (MCV) and serum creatinine. Results: Folate supplementation significantly increased plasma folate by 687% (p < 0.005) and decreased homocysteine by 37% (p < 0.05) with no changes (p > 0.05) in vitamin B 12 or ADMA. There were no significant (p > 0.05) changes in vascular structure or function during the placebo or the folate supplementation phases; IMT; placebo pre mean +/- SD, 0.52 +/- 0.12, post 0.50 +/- 0.11; folate pre 0.55 +/- 0.17, post 0.49 +/- 10.20 mm 5% change in brachial artery diameter (RH, placebo pre 10 +/- 8, post 6 +/- 5; folate pre 9 +/- 7, post 7 +/- 5; GTN, placebo pre 18 +/- 10, post 17 +/- 9, folate pre 16 +/- 9, post-supplementation 18 +/- 8). Conclusion: Three months of folate supplementation decreases plasma homocysteine but has no effect on endothelial function or carotid artery IMT in RTR.

Local geometric changes in left ventricular remodeling post-infarction can lead to apparent reduction in scar thickness

Serial reduction in scar thickness has been shown in animal models. We sought whether this reduction in scar thickness may be a result of dilatation of the left ventricle (LV) with stretching and thinning of the wall. Contrast enhanced magnetic resonance imaging (CMRI) was performed to delineate radial scar thickness in 25 patients (age 63±10, 21 men) after myocardial infarction. The LV was divided into 16 segts and the absolute radial scar thickness (ST) and percentage scar to total wall thickness (%ST) were measured. Regional end diastolic (EDV) and end systolic volumes (ESV) of corresponding segments were measured on CMRI. All patients underwent revascularization and serial changes in ST, %ST, and regional volumes were assessed with a mean follow up of 15±5 months. CMRI identified a total of 93 scar segments. An increase in EDV or ESV was associated with a serial reduction inST(versusEDV, r =−0.3, p = 0.01; versusESV, r =−0.3, p = 0.005) and%ST(versusEDV, r =−0.2, p = 0.04; versus ESV, r =−0.3, p = 0.001). For segts associated with a positive increase in EDV (group I) or ESV (group II) there was a significant decrease in ST and %ST, but in those segts with stable EDV (group III) or ESV (group IV) there were no significant changes in ST and %ST (Table).

Bioimpedance: Is it a predictor of true water volume?

Bioelectrical impedance analysis (BIA) has been reported to be insensitive to changes in water volumes in individual subjects, This study was designed to investigate the effect on the intra- and extracellular resistances (Ri and Re) of the segments of subjects for whom body water was changed without significant change to the total amount of electrolyte in the respective fluids, Twelve healthy adult subjects were recruited. Ri and Re of the leg, trunk, and arm of the subjects were determined from BIA measures prior to commencement of two separate studies that involved intervention, resulting in a loss/gain of body water effected either bt a sauna followed by water intake (study 1) or by ingestion (study 2). Ri and Re of the segments were also determined at a number of times following these interventions, The mean change in body water, expressed as a percentage of body weight, was 0.9% in study 1 and 1.25% in study 2. For each study, the results for each subject were normalized for each limb to the initial (prestudy) value and then the normalized results for each segment were pooled for all subjects, ANOVA of these pooled results failed to demonstrate any significant differences between the normalized mean values of Ri or Re of the segments measured through the course of each study, The failure to detect a change in Ri or Re is explained in terms of the basic theory of BIA.

Visible and near-infrared luminescent Eu(3+) or Er(3+) doped laponite-derived xerogels and thick films: Structural and spectroscopic properties

Laponite-derived materials represent promising materials for optical applications. In this work, Eu(3+)- or Er(3+)-doped laponite xerogels and films were prepared from colloidal dispersion. Homogeneous, crack-free and transparent single layers were deposited on soda-lime substrates with a thickness of 10 mu m. Structural and spectroscopic properties were analyzed by thermal analyses, X-ray diffractometry, transmission electron microscopy, infrared spectroscopy, and luminescence spectroscopy. The addition of a rare earth ion to the laponite does not promote any changes in thermal stability or phase transition. Laponite clay was identified after annealing up to 500 degrees C, with a decrease in basal spacing when the annealing temperature is changed from 100 degrees C to 500 degrees C. Enstatite polymorphs and amorphous silicate phases were observed after heat treatment at 700 degrees C and 900 degrees C. Stationary and time-dependent luminescence spectra in the visible region for Eu(3+), and (5)D(0) lifetime are discussed in terms of thermal treatment and structural evolution. In the layered host, the Eu(3+) ions are distributed in many different local environments. However, Eu(3+) ions were found to occupy at least two symmetry sites, and the ions are preferentially incorporated into the crystalline enstatite for the materials annealed at 700 degrees C and 900 degrees C. A (5)D(0) lifetime of 1.3 ms and 3.1 ms was obtained for Eu(3+) ions in an amorphous silicate and crystalline MgSiO(3) local environment, respectively. Strong Er(3+) emission at the 1550 nm region was observed for the materials annealed at 900 degrees C, with a bandwidth of 44 nm. (C) 2008 Elsevier B.V. All rights reserved.