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Washout
Kinds of Washout Terms modified by Washout Selected AbstractsGadobenate dimeglumine as a contrast agent for MRI of the mouse liverNMR IN BIOMEDICINE, Issue 8 2007Yusuke Inoue Abstract We investigated the characteristics and utility of gadobenate dimeglumine (Gd-BOPTA) for MRI of the mouse liver. Mice were imaged under isoflurane anesthesia using a T1 -weighted, three-dimensional fast low-angle shot (3D FLASH) sequence before and after intravenous or subcutaneous injection of Gd-BOPTA, and the time course of the contrast effect was examined. The appropriate dose for subcutaneous injection was determined visually, and the inter- and intra-observer reproducibilities in liver volumetry were evaluated with and without contrast injection. When mice were imaged sequentially before and after Gd-BOPTA injection and isoflurane anesthesia was maintained throughout the experiment, a long-lasting contrast effect was noted in the liver. Subcutaneous injection caused delayed, but favorable, enhancement. Washout from the liver was definitely accelerated in conscious mice in comparison with anesthetized mice. Visual evaluation indicated that a dose of 0.1,mmol/kg was appropriate for clear delineation of the entire liver margin, and the application of Gd-BOPTA significantly improved the inter- and intra-observer reproducibilities of liver volumetry. In conclusion, the intravenous or subcutaneous injection of Gd-BOPTA has a favorable contrast effect for the mouse liver, resulting in clear visualization of the liver border and improved reproducibility of liver volumetry. The possible influence of anesthesia on the pharmacokinetics of a contrast agent should be considered in determining the optimal scan timing. Copyright © 2007 John Wiley & Sons, Ltd. [source] TOGp regulates microtubule assembly and density during mitosis and contributes to chromosome directional instabilityCYTOSKELETON, Issue 8 2009Lynne Cassimeris Abstract TOGp, a member of the XMAP215 MAP family, is required for bipolar mitotic spindle assembly. To understand how TOGp contributes to spindle assembly, we examined microtubule dynamics after depleting TOGp by siRNA. Fluorescence recovery after photobleaching of GFP-tubulin demonstrated that spindle microtubule turnover is slowed two-fold in the absence of TOGp. Consistent with photobleaching results, microtubule regrowth after washout of the microtubule depolymerizing drug nocodazole was slower at the centrosomes and in the vicinity of mitotic chromatin in cells depleted of TOGp. The slower microtubule turnover is likely due to either nucleation or the transitions of dynamic instability because TOGp depletion did not effect the rate of plus end growth, measured by tracking EB1-GFP at microtubule ends. In contrast, microtubule regrowth after nocodazole washout was unaffected by prior depletion of TACC3, a centrosomal protein that interacts with TOGp. Kinetochore fibers in both untreated and TOGp-depleted cells were stable to incubation at 4°C or lysis in buffer containing calcium indicating that stable kinetochore-microtubule attachments are formed in the absence of TOGp. Depletion of TOGp, but not TACC3, reduced kinetochore oscillations during prometaphase/metaphase. Defects in oscillations are not due simply to multipolarity or loss of centrosome focus in the TOGp-depleted cells, since kinetochore oscillations appear normal in cells treated with the proteosome inhibitor MG132, which also results in multipolar spindles and centrosome fragmentation. We hypothesize that TOGp is required for chromosome motility as a downstream consequence of reduced microtubule dynamics and/or density. Cell Motil. Cytoskeleton 2009. © 2009 Wiley-Liss, Inc. [source] Adenosine induces prolonged anti-,-adrenergic effects in guinea-pig papillary muscleACTA PHYSIOLOGICA, Issue 1 2002L. ARVOLA ABSTRACT A sustained anti- , -adrenergic effect of adenosine has been reported. This study was initiated to investigate this topic and especially elucidate the role of protein kinase C (PKC). Contractile force amplitude and action potential duration at 90% repolarization (APD90) were measured in guinea-pig papillary muscles before and after 5 min challenge with 5 nm isoproterenol. Protocols contained 30 min exposure to the test agents adenosine 33 ,m (ado), adenosine + PKC-inhibitor bisindolylmaleimide 20 nM (ado + BIM), PKC-activator 1,2-dioctanoyl-sn-glycerol 10 ,m (DOG) and , -agonist phenylephrine 5 ,m (phe). Isoproterenol was given at the end of test exposure and after 15 min washout. Results are mean ± SEM of percentage-change, P , 0.05 considered significant and labelled *. The first isoproterenol challenge significantly increased contractile force (27 ± 7%*) in the control group. Responses in the test groups were 2 ± 4 (ado), 1 ± 5 (ado + BIM), 14 ± 4* (DOG), 0 ± 2% (phe). After washout of adenosine, DOG and phenylephrine, isoproterenol induced 3 ± 8 (ado), 23 ± 5* (ado + BIM), 13 ± 5* (DOG), 15 ± 7% (phe) increase in test groups compared with 22 ± 5%* increase in contractile force in the control group. After 45 min washout of adenosine the inotropic response was still significantly reduced compared with control (29 ± 4 vs. 79 ± 8%*). Isoproterenol stimulation shortened APD90 in controls at both time points (5 ± 1%* and 4 ± 1%*), with no significant shortening in test groups. Adenosine induces sustained anti- , -adrenergic effects on contractile force as well as APD90. A role for PKC in signal transduction is supported with respect to contractile force. [source] Statin therapy improves brachial artery vasodilator function in patients with Type 1 diabetes and microalbuminuriaDIABETIC MEDICINE, Issue 3 2005G. K. Dogra Abstract Aims Type 1 diabetes mellitus patients with microalbuminuria have endothelial dysfunction associated with the degree of albuminuria but not with LDL-cholesterol levels. Lipid-lowering agents such as statins may still be of benefit as they can correct endothelial dysfunction by both lipid and non-lipid mechanisms. We therefore examined the effects of atorvastatin on brachial artery endothelial dysfunction in these patients. Methods In a double-blind, randomized crossover study, 16 Type 1 diabetes mellitus patients with microalbuminuria received 6 weeks of atorvastatin 40 mg/day or placebo, separated by a 4-week washout. Brachial artery, endothelium-dependent, flow-mediated dilatation (FMD) and endothelium-independent, glyceryl trinitrate-mediated dilatation (GTNMD) were measured. Results Compared with placebo, atorvastatin produced a significant decrease in apolipoprotein B (34.2%), LDL-cholesterol (44.1%) (all P < 0.001), and oxidized-LDL (35.7%, P = 0.03). There was a non-significant increase in plasma cGMP (P = 0.13) on atorvastatin. FMD and GTNMD increased significantly on atorvastatin (FMD: atorvastatin +1.8 ± 0.4%; placebo +0.2 ± 0.4%, P = 0.007); (GTNMD: atorvastatin +1.3 ± 0.9%; placebo ,1.2 ± 0.6%, P = 0.04). An increase in cGMP was independently correlated with an increase in FMD on atorvastatin (adjusted R2 0.41, P = 0.02). Conclusion Atorvastatin improves endothelium-dependent and independent vasodilator function of the brachial artery in Type 1 diabetes mellitus patients with microalbuminuria. This may relate to pleiotropic effects of statins, in particular reduced oxidative stress and increased availability of nitric oxide. [source] Endoscopic Injection Sclerotherapy for the Treatment of Recurrent Esophageal Varices after Esophageal TransectionDIGESTIVE ENDOSCOPY, Issue 3 2002Hiroshi Yoshida Background: ,We examined the hemodynamic changes associated with recurrent esophageal varices after esophageal transection (ET) and evaluated the effectiveness of endoscopic injection sclerotherapy (EIS) as the treatment for these varices. Methods: ,Nineteen patients with recurrent esophageal varices after ET were treated by EIS. Endoscopic varicealography during injection sclerotherapy, following oral blockage of flow by a balloon, identified three patterns: (i) type 1: common type, continuous filling by the feeder vessel of the varix; (ii) type 2: retrograde-disappearing type, confirmed hepatofugal flow; and (iii) type 3: immediate washout type, immediate washout of contrast medium. Results: ,Angiography revealed that the hepatofugal feeder vessel was the right gastric vein in all cases. Fourteen patients (73.7%) were classified as type 1, 4 patients (21.1%) as type 2, and 1 patient (5.3%) as type 3. Fewer treatment sessions were required in type 1 than in type 2 (P < 0.005). Recurrent varices were completely eradicated in all patients except the patient with type 3 disease. Cumulative re-recurrence rates at 5 and 10 years were similar for types 1 and 2 (28.6 and 71.4%vs 25 and 25%, respectively). The cumulative survival rates after EIS at 5 and 10 years were also similar for types 1 and 2 (77.1 and 66.1%vs 66.7 and 66.7%). Conclusion: ,Endoscopic injection sclerotherapy is an effective treatment for recurrent esophageal varices after ET, except in type 3 disease. Our classification based on endoscopic varicealography during injection sclerotherapy provides knowledge of blood flow within the varices that helps to inform the treatment strategy. [source] Sensitivity and reproducibility of indirect calorimetry in measurement of resting metabolic rateDRUG DEVELOPMENT RESEARCH, Issue 8 2008Cecilia Karlsson Abstract The aim of this study was to assess indirect calorimetry measurement of resting metabolic rate (RMR) with respect to sensitivity and reproducibility in a human study population suitable for early clinical studies to evaluate new anti-obesity candidate drugs. Twenty-four overweight, but otherwise healthy males were included in this randomized, single-blind, placebo-controlled, crossover study. Three different doses of epinephrine (0.005, 0.01, 0.03,µg · kg fat-free mass (FFM),1 · min,1) were used as active treatment. There were two identical study periods, separated by a 4-week washout. Increases in RMR were seen with all tested concentrations of epinephrine when compared with placebo. Changes in RMR of ,1.8% could be detected with 90% power in this crossover study design. The RMR values measured at the two study periods revealed a highly significant correlation (Spearman correlation 0.803, P=0.0007). To conclude, indirect calorimetry is a sensitive and robust means of measuring RMR. The method can be used to assess RMR in diverse clinical settings, even when considering modest differences. Drug Dev Res 69: 2008. © 2008 Wiley-Liss, Inc. [source] Rectal Absorption of Lamotrigine Compressed TabletsEPILEPSIA, Issue 7 2000Angela K. Birnbaum Summary: Purpose: Interruption of oral drug administration poses a significant clinical problem for antiepileptic drugs that have no parenteral formulation. If a drug is absorbed rectally, rectal administration can be a useful alternative when the oral route of administration is not possible. The purpose of this study was to compare the single-dose pharmacokinetics of la-motrigine (LTG) compressed tablets after rectal and oral administration in healthy volunteers. Methods: A single LTG compressed tablet (100 mg) was administered orally and rectally to 12 volunteers in this single-dose, two-period, crossover study with a 2-week washout between doses. For rectal administration, tablets were crushed and suspended in 10 mL of water. Plasma samples were collected from 0 to 120 hr after each dose and analyzed for LTG by an HPLC method developed for this investigation. Results: LTG plasma concentrations were lower after rectal administration versus oral administration. The average area under the curve was 28.90 ± 9.5 ,g/mL/hr after rectal administration and 51.71 ± 19.2 ,g/mL/hr after oral administration. The average maximum LTG concentration was 0.53 ± 0.14 ,g/mL after rectal administration and 1.45 ± 0.35 ,g/mL after oral administration. The relative bioavailability for LTG compressed tablets was 0.63 ± 0.33 for rectal administration. There were no drug-related rashes or serious side effects. Conclusions: LTG suspension prepared from LTG compressed tablets is absorbed rectally, although not to the same extent or rate as when given orally. [source] Nasal nitric oxide measurements before and after repeated humming maneuversEUROPEAN JOURNAL OF CLINICAL INVESTIGATION, Issue 12 2003M. Maniscalco Abstract Background, It has been recently shown that humming greatly increases nasal nitric oxide (NO). This is most likely owing to a rapid washout of sinus NO caused by the oscillating sound waves. During repeated humming manoeuvres nasal NO gradually decreases, likely because NO accumulated in the sinuses is washed out. Aim, We studied whether humming before measurements would affect nasally exhaled NO. Materials and methods, NO output was measured by the chemiluminescence technique in orally and nasally exhaled air in 38 subjects: 18 healthy subjects (HS), 15 subjects with allergic rhinitis (AR) and five subjects with allergic nasal polyposis (AP). Each subject performed a NO measurement during quiet nasal exhalation either preceded by a period of silence/free speaking or immediately after five consecutive humming manoeuvres (posthumming). Results, Mean nasal NO output (95% CI) after a period of silence/free speaking was 231 nL min,1 (178,284) in HS, 434 nL min,1 (347,522) in AR (P < 0·001) and 262 nL min,1 (163,361) in AP. Post-humming nasal NO output was 16% (5 to 50%) lower in HS and 14% (1 to 49%) lower in AR, while it remained unchanged in AP subjects. Intra-subject coefficient of variation of quiet nasal exhalation was 12% in HS, 13% in AR and 5% in AP. Post humming intraindividual coefficient of variation significantly decreased in both HS and AR, but it did not change in AP. Conclusions, Nasal NO levels measured immediately after repeated humming manoeuvres are consistently lower and more reproducible than nasal NO levels measured after a period of silence or free speaking. Repeated humming effectively empties the sinuses, thereby probably minimizing the normal contribution from the sinuses to nasal NO. This may be useful to better estimate NO output from the nasal cavity mucosa in health and disease. [source] Elective coronary angioplasty with 60 s balloon inflation does not cause peroxidative injuryEUROPEAN JOURNAL OF CLINICAL INVESTIGATION, Issue 3 2002K. Cedro Abstract Background The aim of this study was to evaluate the ongoing controversial issue of whether ischemia/reperfusion during elective coronary angioplasty evokes myocardial peroxidative injury. Design We measured indicators of free radical damage to lipids (free malondialdehyde) and proteins (sulphydryl groups) in coronary sinus blood in 19 patients with stable angina who were undergoing elective angioplasty for isolated stenosis of the proximal left anterior descending coronary artery. Ischemia induced by 60 s balloon inflations was confirmed by lactate washout into coronary sinus after deflation, with immediate and 1 min samples. Peroxidative injury was assessed from washout of (a) malondialdehyde measured directly by high performance liquid chromatography and (b) reduced sulphydryl groups, inverse marker of protein oxidative stress. Results Mean lactate concentration immediately after each deflation increased by 120,150% of the initial value, confirming ischemia and showing that blood originated largely from the ischemic region. Lack of myocardial production of malondialdehyde was confirmed by (a) no arteriovenous differences in individual basal concentrations (aortic, range 0·33,12·03 nmol mL,1, mean 7·82; coronary sinus blood, range 0·52,15·82 nmol mL,1, mean 8·18), and (b) after deflations, mean concentrations were not significantly different from preocclusion value. There was no decrease in concentration of sulphydryl groups throughout angioplasty. Conclusion Elective coronary angioplasty with 60 s balloon inflations is a safe procedure that does not induce peroxidative myocardial injury as assessed by methods used in the present study. [source] Metabotropic glutamate receptor 1 activity generates persistent, N -methyl- d -aspartate receptor-dependent depression of hippocampal pyramidal cell excitabilityEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 12 2009J. P. Clement Abstract Metabotropic glutamate receptors (mGluRs) are involved in many forms of neuronal plasticity. In the hippocampus, they have well-defined roles in long-lasting forms of both synaptic and intrinsic plasticity. Here, we describe a novel form of long-lasting intrinsic plasticity that we call (S)-3,5-dihydroxyphenylglycine (DHPG)-mediated long-term depression of excitability (DHPG-LDE), and which is generated following transient pharmacological activation of group I mGluRs. In extracellular recordings from hippocampal slices, DHPG-LDE was expressed as a long-lasting depression of antidromic compound action potentials (cAPs) in CA1 or CA3 cells following a 4-min exposure to the group I mGluR agonist (S)-DHPG. A similar phenomenon was also seen for orthodromic fibre volleys evoked in CA3 axons. In single-cell recordings from CA1 pyramids, DHPG-LDE was manifest as persistent failures in antidromic action potential generation. DHPG-LDE was blocked by (S)-(+)- a -amino-4-carboxy-2-methylbenzeneacetic acid (LY367385), an antagonist of mGluR1, but not 2-methyl-6-(phenylethynyl)pyridine hydrochloride (MPEP), an mGluR5 inhibitor. Although insensitive to antagonists of ,-amino-3-hydroxyl-5-methyl-4-isoxazole-propionate/kainate and ,-aminobutyric acidA receptors, DHPG-LDE was blocked by antagonists of N -methyl- d -aspartate (NMDA) receptors. Similarly, in single-cell recordings, DHPG-mediated antidromic spike failures were eliminated by NMDA receptor antagonism. Long after (S)-DHPG washout, DHPG-LDE was reversed by mGluR1 antagonism. A 4-min application of (S)-DHPG also produced an NMDA receptor-dependent persistent depolarization of CA1 pyramidal cells. This depolarization was not solely responsible for DHPG-LDE, because a similar level of depolarization elicited by raising extracellular K+ increased the amplitude of the cAP. DHPG-LDE did not involve HCN channels or protein synthesis, but was eliminated by blockers of protein kinase C or tyrosine phosphatases. [source] ,-Conotoxin CVIB differentially inhibits native and recombinant N- and P/Q-type calcium channelsEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 2 2007Leonid Motin Abstract ,-Conotoxins are routinely used as selective inhibitors of different classes of voltage-gated calcium channels (VGCCs) in excitable cells. In the present study, we examined the potent N-type VGCC antagonist ,-conotoxin CVID and non-selective N- and P/Q-type antagonist CVIB for their ability to block native VGCCs in rat dorsal root ganglion (DRG) neurons and recombinant VGCCs expressed in Xenopus oocytes. ,-Conotoxins CVID and CVIB inhibited depolarization-activated whole-cell VGCC currents in DRG neurons with pIC50 values of 8.12 ± 0.05 and 7.64 ± 0.08, respectively. Inhibition of Ba2+ currents in DRG neurons by CVID (, 66% of total) appeared to be irreversible for >,30 min washout, whereas Ba2+ currents exhibited rapid recovery from block by CVIB (, 80% within 3 min). The recoverable component of the Ba2+ current inhibited by CVIB was mediated by the N-type VGCC, whereas the irreversibly blocked current (, 22% of total) was attributable to P/Q-type VGCCs. ,-Conotoxin CVIB reversibly inhibited Ba2+ currents mediated by N- (CaV2.2) and P/Q- (CaV2.1), but not R- (CaV2.3) type VGCCs expressed in Xenopus oocytes. The ,2,1 auxiliary subunit co-expressed with CaV2.2 and CaV2.1 reduced the sensitivity of VGCCs to CVIB but had no effect on reversibility of block. Determination of the NMR structure of CVIB identified structural differences to CVID that may underlie differences in selectivity of these closely related conotoxins. ,-Conotoxins CVIB and CVID may be useful as antagonists of N- and P/Q-type VGCCs, particularly in sensory neurons involved in processing primary nociceptive information. [source] Exogenous nitric oxide causes potentiation of hippocampal synaptic transmission during low-frequency stimulation via the endogenous nitric oxide,cGMP pathwayEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 4 2001Christelle L. M. Bon Abstract Nitric oxide (NO) is a putative participant in synaptic plasticity and demonstrations that exogenous NO can elicit the same plastic changes have been taken to support such a role. The experiments, carried out on the CA1 region of rat hippocampal slices, were aimed at testing this interpretation. A major component of tetanus-induced long-term potentiation (LTP) was lost in response to l -nitroarginine, which inhibits NO synthase, and 1H -[1,2,4]oxadiazolo[4,3- a]quinoxalin-1-one (ODQ), which inhibits NO-sensitive soluble guanylyl cyclase (sGC). At 0.2 Hz afferent fibre stimulation, exogenous NO produced, concentration-dependently, a synaptic depression that reverted on washout to a persistent potentiation that occluded tetanus-induced LTP. The NO concentrations necessary (estimated in the 100-nm range), however, were mostly supramaximal for stimulating hippocampal slice sGC activity. Nevertheless the potentiation, but not the preceding depression, was blocked by ODQ. l -nitroarginine and an NMDA antagonist were similarly effective, indicating mediation by the endogenous NMDA receptor,NO synthase,sGC pathway. At a concentration normally too low to affect synaptic transmission but sufficient to stimulate sGC (estimated to be 50 nm), exogenous NO reversed the effect of l -nitroarginine and caused a potentiation which was blocked by ODQ. At a concentration inducing the depression/potentiation sequence, NO partially inhibited hippocampal slice oxygen consumption. It is concluded that, at physiological levels, exogenous NO can directly elicit a potentiation of synaptic transmission through sGC, provided that the synapses are suitably primed. At higher concentrations, NO inhibits mitochondrial respiration, which can result in an enduring synaptic potentiation due to secondary activation of the endogenous NO,cGMP pathway. [source] A comparative study on the effects of naltrexone and loratadine on uremic pruritusEXPERIMENTAL DERMATOLOGY, Issue 9 2004E. Legroux-Crespel Two recent studies have provided opposite results on the efficacy of naltrexone on uremic pruritus. We have performed a third study. We compared efficacy and tolerance of naltrexone and loratadine on uremic pruritus. Among 296 hemodialysed patients, 65 suffered from uremic pruritus. 52 patients participated in the study. Patients were treated for 2 weeks with naltrexone (50 mg/day; 26 patients) or loratadine (10 mg/day; 26 patients), after a washout of 48 h. Pruritus intensity was scored by a visual analog scale (VAS). Adverse events were carefully searched. The two groups were statistically equivalent. There was no significant difference in the mean VAS scores after treatment, but naltrexone allowed a dramatic decrease of VAS sores (, > 3/10) in seven patients. Adverse events (mainly nausea and sleep disturbances) were observed in 10 of 26 patients. We could notice that 22% of hemodialysed patients suffered from uremic pruritus. Naltrexone was effective only in a subset of patients. Adverse events were very frequent. The differences of efficacy and tolerance between patients might be due to metabolism. Naltrexone might be considered as a second-line treatment. [source] Evidence for an amphipathicity independent cellular uptake of amphipathic cell-penetrating peptidesFEBS JOURNAL, Issue 19 2000Anne Scheller The cellular uptake of a peptide set derived from membrane-permeable ,-helical amphipathic peptides by stepwise alterations of structure forming propensity and charge was studied by confocal laser scanning microscopy (CLSM) combined with HPLC. For CLSM monitoring, an online protocol was employed that avoided bias of the uptake results by washout. Using this protocol, extensive fluorescence, approaching the intensity of the external peptide, was observed in the cytosol and nucleus within minutes in all cases, irrespective of the degree of amphipathicity. HPLC analyses of the cell lysates revealed the unmetabolized peptides to be the predominant source of the intracellular fluorescence. Significant amphipathicity-dependent differences became apparent only after washing the peptide-loaded cells, reflecting the effects of amphipathicity on resistance to wash out. Exposure of the cells to the peptides at 37 and 0 °C led to similar results, indicating the nonendocytic character of the uptake. With a view to practical applications , the results of the present study open the possibility of exploiting nonamphipathic peptides as vectors for translocating polar compounds into the cell interior, which would circumvent substantial obstacles currently connected with the use of amphipathic vector peptides, such as membrane toxicity and low solubility. Moreover, differences in the uptake of several members of the investigated peptide series into different cell types present a promising basis for the design of cell-type specific vector peptides. [source] Conduction block and glial injury induced in developing central white matter by glycine, GABA, noradrenalin, or nicotine, studied in isolated neonatal rat optic nerveGLIA, Issue 11 2009Stavros Constantinou Abstract The damaging effects of excessive glutamate receptor activation have been highlighted recently during injury in developing central white matter. We have examined the effects of acute exposure to four other neurotransmitters that have known actions on white matter. Eighty minutes of Glycine or GABA-A receptor activation produced a significant fall in the compound action potential recorded from isolated post-natal day 10 rat optic nerve. This effect was largely reversed upon washout. Nicotinic acetylcholine receptor (nAChR) or adrenoreceptor activation with noradrenalin resulted in an ,35% block of the action potential that did not reverse during a 30-min washout period. While the effect of nAChR activation was blocked by a nAChR antagonist, the effect of noradrenalin was not ablated by ,- or ,-adrenoreceptor blockers applied alone or in combination. In the absence of noradrenalin, co-perfusion with ,- and ,-adrenoreceptor blockers resulted in nonreversible nerve failure indicating that tonic adrenoreceptor activation is required for nerve viability, while overactivation of these receptors is also damaging. Nerves exposed to nAChR + adrenoreceptor activation showed no axon pathology but had extensive glial injury revealed by ultrastructural analysis. Oligodendroglia exhibited regions of membrane vacuolization while profound changes were evident in astrocytes and included the presence of swollen and expanded mitochondria, vacuolization, cell processes disintegration, and membrane breakdown. Blinded assessment revealed higher levels of astrocyte injury than oligodendroglial injury. The findings show that overactivation of neurotransmitter receptors other than those for glutamate can produce extensive injury to developing white matter, a phenomenon that may be clinically significant. © 2009 Wiley-Liss, Inc. [source] Diagnosis of hepatic nodules 20 mm or smaller in cirrhosis: Prospective validation of the noninvasive diagnostic criteria for hepatocellular carcinoma,HEPATOLOGY, Issue 1 2008Alejandro Forner This study prospectively evaluates the accuracy of contrast-enhanced ultrasound (CEUS) and dynamic magnetic resonance imaging (MRI) for the diagnosis of nodules 20 mm or smaller detected during ultrasound (US) surveillance. We included 89 patients with cirrhosis [median age, 65 years; male 53, hepatitis C virus 68, Child-Pugh A 80] without prior hepatocellular carcinoma (HCC) in whom US detected a small solitary nodule (mean diameter, 14 mm). Hepatic MRI, CEUS, and fine-needle biopsy (gold standard) (FNB) were performed at baseline. Non-HCC cases were followed (median 23 months) by CEUS/3 months and MRI/6 months. FNB was repeated up to 3 times and on detection of change in aspect/size. Intense arterial contrast uptake followed by washout in the delayed/venous phase was registered as conclusive for HCC. Final diagnoses were: HCC (n = 60), cholangiocarcinoma (n = 1), and benign lesions (regenerative/dysplastic nodule, hemangioma, focal nodular hyperplasia) (n = 28). Sex, cirrhosis cause, liver function, and alpha-fetoprotein (AFP) levels were similar between HCC and non-HCC groups. HCC patients were older and their nodules significantly larger (P < 0.0001). First biopsy was positive in 42 of 60 HCC patients. Sensitivity, specificity, and positive and negative predictive values of conclusive profile were 61.7%, 96.6%, 97.4%, and 54.9%, for MRI, 51.7%, 93.1%, 93.9%, and 50.9%, for CEUS. Values for coincidental conclusive findings in both techniques were 33.3%, 100%, 100%, and 42%. Thus, diagnosis of HCC 20 mm or smaller can be established without a positive biopsy if both CEUS and MRI are conclusive. However, sensitivity of these noninvasive criteria is 33% and, as occurs with biopsy, absence of a conclusive pattern does not rule out malignancy. These results validate the American Association for the Study of Liver Disease (AASLD) guidelines. (HEPATOLOGY 2007.) [source] Improved diagnosis of well-differentiated hepatocellular carcinoma with gadolinium ethoxybenzyl diethylene triamine pentaacetic acid-enhanced magnetic resonance imaging and Sonazoid contrast-enhanced ultrasonographyHEPATOLOGY RESEARCH, Issue 9 2010Natsuko Kawada Aim:, Two new imaging modalities have been developed recently that are directed at the focal liver lesions: gadolinium ethoxybenzyl diethylene triamine pentaacetic acid (Gd-EOB-DTPA)-enhanced magnetic resonance imaging (MRI) and Sonazoid contrast-enhanced ultrasonography (CEUS). We investigated the usefulness of these modalities for the diagnosis of small (<2 cm), well-differentiated hepatocellular carcinoma (HCC). Methods:, A total of 15 nodules from 13 patients, which were histologically diagnosed as well-differentiated HCC, were subjected to this study. Lesions that showed hypervascularity in the arterial phase and washout in the portal or late non-hemodynamic phase were regarded as HCC in the dynamic studies of all imaging modalities. Results:, By multidetector computed tomography (MDCT), six of 15 (40%) nodules were diagnosed as HCC. Gd-EOB-DTPA-enhanced MRI diagnosed HCC in nine of the 15 (60%) nodules. Of the nine nodules that were not diagnosed by MDCT, four could be diagnosed by Gd-EOB-DTPA-enhanced MRI. In Sonazoid CEUS, 10 of 15 nodules (67%) were diagnosed as HCC. Four of nine nodules that could not be diagnosed as HCC by MDCT, were diagnosed by Sonazoid CEUS. A total of 11 of the 15 (73%) nodules were diagnosed as HCC by Gd-EOB-DTPA-enhanced MRI and Sonazoid CEUS in addition to MDCT. Conclusion:, Gd-EOB-DTPA-enhanced MRI and Sonazoid CEUS had greater diagnostic value for small, well-differentiated HCC than did conventional MDCT. [source] Regulatory processes interacting to maintain hepatic blood flow constancy: Vascular compliance, hepatic arterial buffer response, hepatorenal reflex, liver regeneration, escape from vasoconstrictionHEPATOLOGY RESEARCH, Issue 11 2007W. Wayne Lautt Constancy of hepatic blood flow (HBF) is crucial for several homeostatic roles. The present conceptual review focuses on interrelated mechanisms that act to maintain a constant HBF per liver mass. The liver cannot directly control portal blood flow (PF); therefore, these mechanisms largely operate to compensate for PF changes. A reduction in PF leads to reduced intrahepatic distending pressure, resulting in the highly compliant hepatic vasculature passively expelling up to 50% of its blood volume, thus adding to venous return, cardiac output and HBF. Also activated immediately upon reduction of PF are the hepatic arterial buffer response and an HBF-dependent hepatorenal reflex. Adenosine is secreted at a constant rate into the small fluid space of Mall which surrounds the terminal branches of the hepatic arterioles, portal venules and sensory nerves. The concentration of adenosine is regulated by washout into the portal venules. Reduced PFreduces the washout and the accumulated adenosine causes dilation of the hepatic artery, thus buffering the PF change. Adenosine also activates hepatic sensory nerves to cause reflex renal fluid retention, thus increasing circulating blood volume and maintaining cardiac output and PF. If these mechanisms are not able to maintain total HBF, the hemodynamic imbalance results in hepatocyte proliferation, or apoptosis, by a shear stress/nitric oxide-dependent mechanism, to adjust total liver mass to match the blood supply. These mechanisms are specific to this unique vascular bed and provide an excellent example of multiple integrative regulation of a major homeostatic organ. [source] Brain region binding of the D2/3 agonist [11C]-(+)-PHNO and the D2/3 antagonist [11C]raclopride in healthy humansHUMAN BRAIN MAPPING, Issue 4 2008Ariel Graff-Guerrero Abstract The D2 receptors exist in either the high- or low-affinity state with respect to agonists, and while agonists bind preferentially to the high-affinity state, antagonists do not distinguish between the two states. [11C]-(+)-PHNO is a PET D2agonist radioligand and therefore provides a preferential measure of the D2high receptors. In contrast, [11C]raclopride is an antagonist radioligand and thus binds with equal affinity to the D2 high- and low-affinity states. The aim was to compare the brain uptake, distribution and binding characteristics between [11C]-(+)-PHNO and [11C]raclopride in volunteers using a within-subject design. Both radioligands accumulated in brain areas rich in D2/D3 -receptors. However, [11C]-(+)-PHNO showed preferential uptake in the ventral striatum and globus pallidus, while [11C]raclopride showed preferential uptake in the dorsal striatum. Mean binding potentials were higher in the putamen (4.3 vs. 2.8) and caudate (3.4 vs 2.1) for [11C]raclopride, equal in the ventral-striatum (3.4 vs. 3.3), and higher in the globus pallidus for [11C]-(+)-PHNO (1.8 vs. 3.3). Moreover [11C]-(+)-PHNO kinetics in the globus pallidus showed a slower washout than other regions. One explanation for the preferential binding of [11C]-(+)-PHNO in the globus pallidus and ventral-striatum could be the presence of a greater proportion of high- vs. low-affinity receptors in these areas. Alternatively, the observed distribution could also be explained by a preferential binding of D3 -over-D2 with [11C]-(+)-PHNO. This differential binding of agonist vs. antagonist radioligand, especially in the critically important region of the limbic striatum/pallidum, offers new avenues to investigate the role of the dopamine system in health and disease. Hum Brain Mapp 2008. © 2007 Wiley-Liss, Inc. [source] Hydrogeochemical balance of forest umbrisol profiles (,Sierra de Gata', central western Spain)HYDROLOGICAL PROCESSES, Issue 14 2007I. Menéndez Abstract Three techniques for obtaining soil water solutions (gravitational and matrical waters extracted using both in situ tension lysimeters and in vitro pressure chambers) and their later chemical analysis were performed in order to know the evolution of the soil-solution composition when water moves down through the soil, from the Ah soil horizon to the BwC- or C-horizons of forest soils located in western Spain. Additionally, ion concentrations and water volumes of input waters to soil (canopy washout) and exported waters (drainage solutions from C-horizons) were determined to establish the net balance of solutes in order to determine the rates of leaching or retention of ions. A generalized process of sorption or retention of most components (even Cl,) was observed, from the soil surface to the C-horizon, in both gravitational and matrical waters, with H4SiO4, Mn2+, Na+, and SO42, being the net exported components from the soil through the groundwater. These results enhance the role of the recycling effect in these forest soils. The net percentages of elements retained in these forest soils, considering the inputs and the outputs balance, were 68% K+, 85% Ca2+, 58% Mg2+, 7% Al3+, 5% Fe3+, 34% Zn2+, 57% Cl,, and 20% NO3,, and about 75% of dissolved organic carbon was mineralized. Copyright © 2007 John Wiley & Sons, Ltd. [source] Vorinostat increases carboplatin and paclitaxel activity in non-small cell lung cancer cellsINTERNATIONAL JOURNAL OF CANCER, Issue 3 2010Taofeek K. Owonikoko Abstract We observed a 53% response rate in non-small cell lung cancer (NSCLC) patients treated with vorinostat plus paclitaxel/carboplatin in a Phase I trial. Studies were undertaken to investigate the mechanism (s) underlying this activity. Growth inhibition was assessed in NSCLC cells by MTT assay after 72 hr of continuous drug exposure. Vorinostat (1 ,M) inhibited growth by: 17% ± 7% in A549, 28% ± 6% in 128-88T, 39% ± 8% in Calu1 and 41% ± 7% in 201T cells. Vorinostat addition to carboplatin or paclitaxel led to significantly greater growth inhibition than chemotherapy alone in all 4 cell lines. Vorinostat (1 ,M) synergistically increased the growth inhibitory effects of carboplatin/paclitaxel in 128-88T cells. When colony formation was measured after drug withdrawal, vorinostat significantly increased the effects of carboplatin but not paclitaxel. The % colony formation was control 100%; 1 ,M vorinostat, 83% ± 10%; 5 ,M carboplatin, 41% ± 11%; carboplatin/vorinostat, 8% ± 4%; 2 nM paclitaxel, 53% ± 11%; paclitaxel/vorinostat, 46% ± 21%. In A549 and 128-88T, vorinostat potentiated carboplatin induction of gamma-H2AX (a DNA damage marker) and increased ,-tubulin acetylation (a marker for stabilized mictrotubules). In A549, combination of vorinostat with paclitaxel resulted in a synergistic increase in ,-tubulin acetylation, which reversed upon drug washout. We conclude that vorinostat interacts favorably with carboplatin and paclitaxel in NSCLC cells, which may explain the provocative response observed in our clinical trial. This likely involves a vorinostat-mediated irreversible increase in DNA damage in the case of carboplatin and a reversible increase in microtubule stability in the case of paclitaxel. [source] Improvement in duration of erection following phosphodiesterase type 5 inhibitor therapy with vardenafil in men with erectile dysfunction: the ENDURANCE studyINTERNATIONAL JOURNAL OF CLINICAL PRACTICE, Issue 1 2009M. T. Rosenberg Summary Objective:, The ENDURANCE study evaluated the efficacy of vardenafil, a phosphodiesterase type 5 (PDE5) inhibitor, in men with erectile dysfunction (ED), by measuring the duration of erection leading to successful intercourse using a stopwatch as the assessment instrument. Methods:, This was a randomised, multicentre, double-blind, placebo-controlled, crossover study consisting of a 4-week treatment-free run-in phase after which patients were randomised to either fixed-dose vardenafil 10 mg or placebo (to be administered 60 min prior to intercourse) and entered the first of the two 4-week double-blind treatment periods, separated by a 1-week washout. The primary efficacy end-point was the stopwatch-assessed duration of erection, which was defined as the time from erection perceived hard enough for penetration until withdrawal from the partner's vagina leading to successful intercourse as measured by Sexual Encounter Profile Question 3 (SEP-3). Secondary efficacy end-points included SEP-2 and SEP-3 success rates, the erectile function domain of the International Index of Erectile Function, global assessment questionnaire, change from baseline in duration of erection and duration of erection not leading to successful intercourse. Safety was assessed by adverse events (AEs), laboratory samples, vital signs and ECGs. Results:, Of the 191 men included in the safety population, 40% had moderate ED and 33% had severe ED at baseline. The duration of erection (least squares mean ± SE) leading to successful intercourse was longer with vardenafil than with placebo (12.81 ± 1.00 min vs. 5.45 ± 1.00 min; p < 0.001). The differences recorded for all secondary end-points were statistically significant in favour of vardenafil compared with placebo (p < 0.001), with the exception of duration of erection not leading to successful intercourse. Vardenafil was well tolerated in this study; the majority of AEs being mild-to-moderate in intensity. Conclusion:, Vardenafil 10-mg therapy provided a statistically superior duration of erection leading to successful intercourse in men with ED compared with placebo. [source] Post-conditioning with cyclosporine A fails to reduce the infarct size in an in vivo porcine modelACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 7 2010R. H. LIE Background: Cyclosporine A has generated intense interest in the field of cardioprotection due to its ability to protect the mitochondria at reperfusion by blocking the opening of the mitochondrial permeability transition pore. The aim of our study was to examine the cardioprotective effect of Sandimmun®, a clinically available formulation of cyclosporine A, in an in vivo large mammal model. Methods: Forty-eight pigs were randomly allocated to one of three groups: (i) Control group (Con, n=19), (ii) Cyclosporine group, (Cyclo, n=19) Sandimmun® 10 mg/kg i.v. bolus 5 min before reperfusion and (iii) Pre-conditioning group (Precon, n=10) two cycles of 10 min ischemia interspersed with 30-min reperfusion. The study was further sub-divided into a metabolic protocol, evaluating myocardial metabolism by measuring changes in the interstitial lactate concentration, and a coronary flow protocol. All animals were subjected to 40 min of left anterior descending coronary artery occlusion, followed by 180 min of reperfusion before histochemical staining and assessment of infarct size by planimetry. Results: Infarct sizes were measured as: Con 51.4 ± 16.5%, Cyclo 47.3 ± 15.7% and Precon 2.4 ± 3.6%, with no significant difference between the Con and Cyclo groups but a highly significant difference between the Precon and Cyclo and Con groups (P<0.0001 for both comparisons). In the Cyclo group, the interstitial lactate concentration was significantly increased compared with the Con group at 6-min reperfusion, although significantly lower at 14 min presumably due to accelerated washout. Conclusion: In this large animal model, a 10 mg/kg bolus administration of Sandimmun® 5 min before reperfusion did not reduce the infarct size. [source] Clinicopathological review of 46 primary retroperitoneal tumorsINTERNATIONAL JOURNAL OF UROLOGY, Issue 9 2007Mitsuhiro Tambo Objectives: To clarify the clinical factors including diagnostic imaging findings that may correlate with the histopathological malignancy in primary retroperitoneal tumors. Methods: The clinical backgrounds and imaging findings of 22 benign and 24 malignant primary retroperitoneal tumors were retrospectively investigated, and the prognosis of patients with malignant retroperitoneal tumors was assessed. Results: There were significant correlations between the presence of symptoms and malignancy (P < 0.01), as well as between the irregularity of tumor margins and malignancy (P < 0.01). On dynamic magnetic resonance imaging (MRI), 90% of malignant tumors showed early enhancement either with quick or slow washout, while 75% of benign tumors showed delayed and no enhancement (P < 0.002). All malignant and benign paraganglioma showed the same early enhancement with quick washout. Malignant lymphoma showed various enhancement patterns. The 2-year and 5-year cause-specific survival rates of the patients with malignant retroperitoneal tumors were 68.0% and 43.2%, respectively. All malignant lymphoma patients were mainly treated with chemotherapy after being diagnosed histologically. Malignant paraganglioma patients who could not meet complete resection needed chemotherapy for promising survival. Conclusion: The symptoms, the irregularity of the margins, and the specific enhancement pattern on the dynamic MRI may be important predictive factors of the primary malignant retroperitoneal tumors. Histological diagnosis was needed for malignant definition of paraganglioma because both benign and malignant paraganglioma showed similar clinical and imaging findings. Preoperative biopsy should be considered for selection of the appropriate treatment particularly in patients that are likely to have malignant lymphoma that could not be diagnosed definitively by the clinical and imaging findings. [source] Validation and clinical feasibility of nitrogen washin/washout functional residual capacity measurements in childrenACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 3 2010C. OLEGĹRD Background: The functional residual capacity (FRC) is an important parameter in pediatric respiratory monitoring but it is difficult to assess in the clinical setting. We have introduced a modified N2 washout method utilizing a change of FIO2 of 0.1 for FRC measurement in adult respiratory monitoring. This study validated the algorithm in a pediatric lung model and investigated the stability and feasibility in a pediatric peri-operative and intensive care setting. Methods: The lung model was ventilated in combinations of ventilatory modes, CO2 production, model FRC and respiratory rates. Sixteen children from 10 days to 5 years were studied peri-operatively with controlled ventilation using a Mapleson D system and in the intensive care unit using a Servo-i ventilator in a supported spontaneous mode. FRC was measured during stable metabolic, respiratory and circulatory periods at positive end expiratory pressure of 3,4 and 7,8 cmH2O. Results: In the model and in the clinical setting, we found an excellent agreement between washout and washin measurements of FRC as well as acceptable coefficients of repeatability. Conclusion: FRC was satisfactorily measured by a modified N2 algorithm and may be included as a monitoring variable in pediatric respiratory care. Pediatric FRC monitoring demands strictly stable conditions as measurements are performed close to the limits of the monitor's specifications. [source] Cadmium accumulation and binding characteristics in intact Sertoli/germ cell units, and associated effects on stage-specific functions in vitro: insights from a shark testis modelJOURNAL OF APPLIED TOXICOLOGY, Issue 2 2008Leon M. McClusky Abstract The increased human use of cadmium (Cd) and its increased occurrence in the environment is of concern. The testis is sensitive to Cd because of the steroid-mediated regulation of spermatogenesis, high levels of DNA synthesis and gene transcription, all of which varies in a stage-related manner. Validated techniques (acridine orange vital staining to detect apoptosis and dextran-rhodamine exclusion to assess blood,testis barrier function) were recently developed and the shark testis was proposed as an alternative model for assessing stage-specific functions in living testicular tissue and to study toxicant actions on spermatogenesis. The present paper shows that 109Cd accumulation and binding in vitro was stage-dependent (premeiotic, PrM > meiotic, M > postmeiotic, PoM), rapid and persisted in spermatocysts (intact germ cell/Sertoli cell units) 49 h after washout. In competitive binding analyses of all three spermatocyst stages, Hg, but not Zn, could replace bound 109Cd, suggesting that Cd binding was specific. These findings were associated with a biphasic apoptotic response in the PrM spermatocysts, which was maximal at 10 µm CdCl2 and 1 µm CdCl2 after 2 and 4 days in culture, respectively. Although Cd uptake in PoM cysts was more than 2-fold less than uptake in PrM cysts, the percentage dextran-rhodamine permeant PoM cysts was ,8-fold greater than in controls in the presence of both 10 µm CdCl2 and 30 µm CdCl2 after 4 days culture, indicating that blood,testis barrier function in PoM spermatocysts was compromised. These findings demonstrate that this model has utility for use in screening assays of environmental toxicants. Copyright © 2007 John Wiley & Sons, Ltd. [source] Systems biology approaches for toxicology,JOURNAL OF APPLIED TOXICOLOGY, Issue 3 2007William Slikker Jr Abstract Systems biology/toxicology involves the iterative and integrative study of perturbations by chemicals and other stressors of gene and protein expression that are linked firmly to toxicological outcome. In this review, the value of systems biology to enhance the understanding of complex biological processes such as neurodegeneration in the developing brain is explored. Exposure of the developing mammal to NMDA (N -methyl- d -aspartate) receptor antagonists perturbs the endogenous NMDA receptor system and results in enhanced neuronal cell death. It is proposed that continuous blockade of NMDA receptors in the developing brain by NMDA antagonists such as ketamine (a dissociative anesthetic) causes a compensatory up-regulation of NMDA receptors, which makes the neurons bearing these receptors subsequently more vulnerable (e.g. after ketamine washout), to the excitotoxic effects of endogenous glutamate: the up-regulation of NMDA receptors allows for the accumulation of toxic levels of intracellular Ca2+ under normal physiological conditions. Systems biology, as applied to toxicology, provides a framework in which information can be arranged in the form of a biological model. In our ketamine model, for example, blockade of NMDA receptor up-regulation by the co-administration of antisense oligonucleotides that specifically target NMDA receptor NR1 subunit mRNA, dramatically diminishes ketamine-induced cell death. Preliminary gene expression data support the role of apoptosis as a mode of action of ketamine-induced neurotoxicity. In addition, ketamine-induced cell death is also prevented by the inhibition of NF- ,B translocation into the nucleus. This process is known to respond to changes in the redox state of the cytoplasm and has been shown to respond to NMDA-induced cellular stress. Although comprehensive gene expression/proteomic studies and mathematical modeling remain to be carried out, biological models have been established in an iterative manner to allow for the confirmation of biological pathways underlying NMDA antagonist-induced cell death in the developing nonhuman primate and rodent. Published in 2007 John Wiley & Sons, Ltd. [source] Crushed Clopidogrel Administered via Nasogastric Tube Has Faster and Greater Absorption than Oral Whole TabletsJOURNAL OF INTERVENTIONAL CARDIOLOGY, Issue 4 2009M. UROOJ ZAFAR M.B.B.S. Objectives: To compare the absorption of 300 mg clopidogrel administered crushed via nasogastric (NG) tube versus whole tablets taken orally in healthy volunteers. Background: Earlier antiplatelet therapy has proven benefits in treatment of myocardial infarction and in patients undergoing PCI. Aspirin can be delivered early in crushed form via NG tube after CABG surgery to prevent graft occlusion. If clopidogrel given crushed via NG tube provides faster absorption, it could allow earlier clopidogrel loading. Methods: Nine healthy human subjects (34.7 ± 11.1 years, 5 males) were given 300 mg clopidogrel in crushed form via NG tube with 30 mL water after 8 hours of fasting. Plasma levels of the primary circulating inactive clopidogrel metabolite SR26334 were measured after 20 minutes, 40 minutes, 1, 2, 4, 8, 12, and 24 hours of dosing. Following ,2 week washout, same subjects swallowed 300 mg clopidogrel (four 75 mg tablets) after an 8-hour fasting and SR26334 levels were measured at the same time points. Results: Plasma SR26334 concentrations peaked earlier after crushed delivery than after oral intake (44 vs. 70 minutes, P = 0.023) and the median peak was 80% higher (13,083 vs. 7,255 ng/mL, respectively, P = 0.021). At 40 minutes, area under the curve was almost twofold greater with NG administration than oral administration (geometric means ratio = 0.5299, 95% CI = 0.28,0.99, P = 0.048), but was similar over the 24-hour period with both administration methods (geometric means ratio = 1.05, 95% CI = 0.84,1.32, P = 0.646). Conclusions: A 300 mg loading dose of crushed clopidogrel administered via NG tube provides faster and greater bioavailability than an equal dose taken orally as whole tablets. The clinical benefits of this strategy need to be investigated. [source] Bi-directional modulation of fast inhibitory synaptic transmission by leptinJOURNAL OF NEUROCHEMISTRY, Issue 1 2009Natasha Solovyova Abstract The hormone leptin has widespread actions in the CNS. Indeed, leptin markedly influences hippocampal excitatory synaptic transmission and synaptic plasticity. However, the effects of leptin on fast inhibitory synaptic transmission in the hippocampus have not been evaluated. Here, we show that leptin modulates GABAA receptor-mediated synaptic transmission onto hippocampal CA1 pyramidal cells. Leptin promotes a rapid and reversible increase in the amplitude of evoked GABAA receptor-mediated inhibitory synaptic currents (IPSCs); an effect that was paralleled by increases in the frequency and amplitude of miniature IPSCs, but with no change in paired pulse ratio or coefficient of variation, suggesting a post-synaptic expression mechanism. Following washout of leptin, a persistent depression (inhibitory long-lasting depression) of evoked IPSCs was observed. Whole-cell dialysis or bath application of inhibitors of phosphoinositide 3 (PI 3)-kinase or Akt prevented leptin-induced enhancement of IPSCs indicating involvement of a post-synaptic PI 3-kinase/Akt-dependent pathway. In contrast, blockade of PI 3-kinase or Akt activity failed to alter the ability of leptin to induce inhibitory long-lasting depression, suggesting that this process is independent of PI 3-kinase/Akt. In conclusion these data indicate that the hormone leptin bi-directionally modulates GABAA receptor-mediated synaptic transmission in the hippocampus. These findings have important implications for the role of this hormone in regulating hippocampal pyramidal neuron excitability. [source] Inhibition of neural activity depletes orexin from rat hypothalamic slice cultureJOURNAL OF NEUROSCIENCE RESEARCH, Issue 1 2010Shotaro Michinaga Abstract Orexins (hypocretins) are neuropeptides produced by a small population of hypothalamic neurons whose dysregulation may lead to narcolepsy, a neurological disorder characterized by disorganization of sleep and wakefulness. Excessive stimulation of the N-methyl-D-aspartate (NMDA) subtype of glutamate receptors causes preferential loss of orexin neurons in the hypothalamus, whereas an adequate level of neuronal excitatory activities is generally known to be important for the maintenance of central neurons. By examining the effect of manipulation of neural activity, we found that 24,72 hr application of tetrodotoxin (TTX) caused a substantial decrease in the number of orexin-immunoreactive neurons, but not of melanin-concentrating hormone-immunoreactive neurons, in hypothalamic slice culture. Similar results were obtained when neural activity was arrested by added extracellular Mg2+. Reduction of orexin expression by TTX and Mg2+ was also observed at mRNA level. The decrease of orexin-immunoreactive neurons was attributable to depletion of orexin, because it was reversible after washout of TTX or elevated extracellular Mg2+ and was not associated with induction of cell death. Blockers of voltage-dependent Ca2+ channels as well as of NMDA receptors also induced a significant and selective decrease of orexin-immunoreactive neurons. Moreover, TTX-induced decrease of orexin immunoreactivity was largely abrogated by concurrent application of a moderate concentration of NMDA. These results suggest that Ca2+ entry associated with nontoxic levels of spontaneous activity of glutamatergic inputs plays an important role in the maintenance of orexin neurons in a tissue culture model. © 2009 Wiley-Liss, Inc. [source] | ||||||||||||||||||||||||||||||||||||||||