Predictive values of aspartate aminotransferase and gamma-glutamyl transferase for the hepatic accumulation of copper in cattle and buffalo

Ten cattle and 10 buffalo were divided into 2 groups (control [n = 8] and experimental [n = 12]) that received daily administration of copper. Three hepatic biopsies and blood samples were performed on days 0, 45, and 105. The concentration of hepatic copper was determined by spectrophotometric atomic absorption, and the activities of aspartate aminotransferase (AST) and gamma-glutamyl transferase (GGT) were analyzed. Regression analyses were done to verify the possible existing relationship between enzymatic activity and concentration of hepatic copper. Sensitivity, specificity, accuracy, and positive and negative predictive values were determined. The serum activities of AST and GGT had coefficients of determination that were excellent predictive indicators of hepatic copper accumulation in cattle, while only GGT serum activity was predictive of hepatic copper accumulation in buffalo. Elevated serum GGT activity may be indicative of increased concentrations of hepatic copper even in cattle and buffalo that appear to be clinically healthy. Thus, prophylactic measures can be implemented to prevent the onset of a hemolytic crisis that is characteristic of copper intoxication.

The effect of 5 days of aspartate and asparagine supplementation on glucose transport activity in rat muscle

The consumption of protein supplements containing amino acids is increasing around the world Aspartate (Asp) and asparagine (Asn) are amino acids metabolized by skeletal muscle. This metabolism involves biochemical pathways that are involved in increasing Krebs cycle activity via anaplerotic reactions. resulting in higher glutamine concentrations. A connection between amino acid supplementation, glycogen concentration, and glucose uptake has been previously demonstrated. The purpose of this study was to evaluate the effect of asp and Asn Supplementation on glucose uptake in rats using three different glycogen concentrations The results indicate that Asp and Asn supplementation in rats with high glycogen concentrations (fed state) further increased the glycogen concentration in the muscle, and decreased in vitro 2-deoxyglucose (a glucose analog.) uptake by the muscle at maximal insulin concentrations When animals had a medium glycogen concentration (consumed lard for 3 days). glucose uptake was higher in the supplemented group at sub-maximal insulin concentrations. We conclude that supplementation of Asp and Asn reduced glucose transport in rat muscle only at higher levels of glycogen. The ingestion of lard for 3 days changed the responsiveness and sensitivity to insulin, and that group had higher levels of insulin sensivity with Asp and Asn supplementation. Copyright (C) 2009 John Wiley & Sons, Ltd.

Structure-activity studies of conantokins as human N-methyl-D-aspartate receptor modulators

The activities of conantokin-G (con-G), conantokin-T (con-T), and several novel analogues have been studied using polyamine enhancement of [H-3]MK-801 binding to human glutamate-N-methyl-D-aspartate (NMDA) receptors, and their structures have been examined using CD and H-1 NMR spectroscopy. The potencies of con-G[A7], con-G, and con-T as noncompetitive inhibitors of spermine-enhanced [H-3]MK-801 binding to NMDA receptor obtained from human brain tissue are similar to those obtained using rat brain tissue. The secondary structure and activity of con-G are found to be highly sensitive to amino acid substitution and modification. NMR chemical shift data indicate that con-G, con-G[D8,D17], and con-G[A7] have similar conformations in the presence of Ca2+. This consists of a helix for residues 2-16, which is kinked in the vicinity of Gla10. This is confirmed by 3D structure calculations on con-G[A7]. Restraining this helix in a linear form (i.e., con-G[A7,E10-K13]) results in a minor reduction in potency. Incorporation of a 7-10 salt-bridge replacement (con-G[K7-E10]) prevents helix formation in aqueous solution and produces a peptide with low potency. Peptides with the Leu5-Tyr5 substitution also have low potencies (con-G[Y5,A7] and con-G[Y5,K7]) indicating that Leu5 in con-G is important for full antagonist behavior. We have also shown that the Gla-Ala7 substitution increases potency, whereas the Gla-Lys7 substitution has no effect. Con-G and con-G[K7] both exhibit selectivity between NMDA subtypes from mid-frontal and superior temporal gyri, but not between sensorimotor and mid-frontal gyri. Asn8 and/or Asn17 appear to be important for the ability of con-G to function as an inhibitor of polyamine-stimulated [3H]MK-801 binding, but not in maintaining secondary structure. The presence of Ca2+ does not increase the potencies of con-G and con-T for NMDA receptors but does stabilize the helical structures of con-G, con-G[D8,D17], and, to a lesser extent, con-G[A7]. The NMR data support the existence of at least two independent Ca2+-chelating sites in con-G, one involving Gla7 and possibly Gla3 and the other likely to involve Gla10 and/or Gla14.

Lower N-Acetyl-Aspartate Levels in Prefrontal Cortices in Pediatric Bipolar Disorder: A (1)H Magnetic Resonance Spectroscopy Study

Objective: The few studies applying single-voxel(1)H spectroscopy in children and adolescents with bipolar disorder (BD) have reported low N-acetyl-aspartate (NAA) levels in the dorsolateral prefrontal cortex (DLPFC), and high myo-inositol / phosphocreatine plus creatine (PCr+Cr) ratios in the anterior cingulate. The aim of this study was to evaluate NAA, glycerophosphocholine plus phosphocholine (GPC+PC) and PCr+Cr in various frontal cortical areas in children and adolescents with BD. We hypothesized that NAA levels within the prefrontal cortex are lower in BD patients than in healthy controls, indicating neurodevelopmental alterations in the former. Method: We studied 43 pediatric patients with DSM-IV BD (19 female, mean age 13.2 +/- 2.9 years) and 38 healthy controls (79 female, mean age 13.9 +/- 2.7 years). We conducted multivoxel in vivo (1)H spectroscopy measurements at 1.5 Tesla using a long echo time of 272 ms to obtain bilateral metabolite levels from the medial prefrontal cortex (MPFC), DLPFC (white and gray matter), cingulate (anterior and posterior), and occipital lobes. We used the nonparametric Mann-Whitney U test to compare neurochemical levels between groups. Results: In pediatric BD patients, NAA and GPC+PC levels in the bilateral MPFC, and PCr+Cr levels in the left MPFC were lower than those seen in the controls. In the left DLPFC white matter, levels of NAA and PCr+Cr were also lower in BD patients than in controls. Conclusions: Lower NAA and PCr+Cr levels in the PFC of children and adolescents with BD may be indicative of abnormal dendritic arborization and neuropil, suggesting neurodevelopmental abnormalities. J. Am. Acad. Child Adolesc. Psychiatry, 2011;50(1):85-94.

Reduced medial prefrontal N-Acetyl-Aspartate levels in pediatric major depressive disorder: A multi-voxel in vivo (1)H spectroscopy study

There is increasing evidence of a reciprocal fronto-limbic network in the pathogenesis of mood disorders. Prior in vivo proton ((1)H) spectroscopy studies provide evidence of abnormal neurochemical levels in the cingulate and dorsolateral prefrontal cortex (DLPFC) of adult subjects with major depressive disorder (MOD). We examined whether similar abnormalities occur in children and adolescents with MDD. We collected two-dimensional multi-voxel in vivo 1H spectroscopy data at 1.5 Tesla to quantify levels of N-acetyl-aspartate (NAA), glycerolphosphocholine plus phosphocholine (GPC + PC), and phosphocreatine plus creatine (PCr + Cr) in the DLPFC, medial prefrontal cortex (MPFC), and anterior cingulate (AC) of children and adolescents aged 8-17 years with MDD (n = 16) compared with healthy control subjects (n = 38). Analysis of covariance with age and gender as covariates was performed. MDD subjects showed significantly lower levels of NAA in the right MPFC and right AC than controls. MDD subjects also had significantly lower levels of GPC + PC in the right AC than control subjects. There were no significant differences in other metabolites in the studied regions. Pediatric patients with MDD exhibit neurochemical alterations in prefrontal cortex regions that are important in the monitoring and regulation of emotional states. (C) 2010 Elsevier Ireland Ltd. All rights reserved.

Role of N-Methyl-D-Aspartate and Non-N-Methyl-D-Aspartate Receptors in the Cardiovascular Effects of L-Glutamate Microinjection Into the Hypothalamic Paraventricular Nucleus of Unanesthetized Rats

We report on the cardiovascular effects of L-glutamate (L-glu) microinjection into the hypothalamic paraventricular nucleus (PVN) as well as the mechanisms involved in their mediation. L-glu microinjection into the PVN caused dose-related pressor and tachycardiac responses in unanesthetized rats. These responses were blocked by intravenous (i.v.) pretreatment with the ganglion blocker pentolinium (PE; 5 mg/kg), suggesting sympathetic mediation. Responses to L-glu were not affected by local microinjection of the selective non-NMDA receptor antagonist NBQX (2 nmol) or by local microinjection of the selective NMDA receptor antagonist LY235959 (LY; 2 nmol). However, the tachycardiac response was changed to a bradycardiac response after treatment with LY235959, suggesting that NMDA receptors are involved in the L-glu heart rate response. Local pretreatment with LY235959 associated with systemic PE or dTyr(CH(2))(5)(Me)AVP (50 mu g/kg) respectively potentiated or blocked the response to L-glu, suggesting that L-glu responses observed after LY235959 are vasopressin mediated. The increased pressor and bradycardiac responses observed after LY + PE was blocked by subsequent i.v. treatment with the V(1)-vasopressin receptor antagonist dTyr(CH(2))(5)(Me)AVP, suggesting vasopressin mediation. The pressor and bradycardiac response to L-glu microinjection into the PVN observed in animals pretreated with LY + PE was progressively inhibited and even blocked by additional pretreatment with increasing doses of NBQX (2, 10, and 20 nmol) microinjected into the PVN, suggesting its mediation by local non-NMDA receptors. In conclusion, results suggest the existence of two glutamatergic pressor pathways in the PVN: one sympathetic pathway that is mediated by NMDA receptors and a vasopressinergic pathway that is mediated by non-NMDA receptors. (C) 2009 Wiley-Liss, Inc.

Non-N-Methyl-D-Aspartate Glutamate Receptors in the Paraventricular Nucleus of Hypothalamus Mediate the Pressor Response Evoked by Noradrenaline Microinjected Into the Lateral Septal Area in Rats

The lateral septal area (LSA) is a part of the limbic system and is involved in cardiovascular modulation. We previously reported that microinjection of noradrenaline (NA) into the LSA of unanesthetized rats caused pressor responses that are mediated by acute vasopressin release. Magnocellular neurons of the paraventricular (PVN) and supraoptic (SON) of the hypothalamus synthesize vasopressin. In the present work, we studied which of these nuclei is involved in the pressor pathway activated by unilateral NA injection into the LSA as well as the local neurotransmitter involved. Chemical ablation of the SON by unilateral injection of the nonspecific synapses blocker cobalt chloride (1 mM/100 nl) did not affect the pressor response evoked by NA (21 nmol/200 nl) microinjection into the LSA. However, the response to NA was blocked when cobalt chloride (1 mM/100 nl) was microinjected into the PVN, indicating that this hypothalamic nucleus is responsible for the mediation of the pressor response. There is evidence in the literature pointing to glutamate as a putative neurotransmitter activating magnocellular neurons. Pretreatment of the PVN with the selective non-N-methyl-D-asparate (NMDA) antagonist NBQX (2 nmol/100 nl) blocked the pressor response to NA microinjected into the LSA, whereas pretreatment with the selective NMDA antagonist LY235959 (2 nmol/100 nl) did not affect the response to NA. Our results implicate the PVN as the final structure in the pressor pathway activated by the microinjection of NA into the LSA. They also indicate that local glutamatergic synapses and non-NMDA glutamatergic receptors mediate the response in the PVN. (c) 2008 Wiley-Liss, Inc.

N-Methyl-D-aspartate glutamate receptors in the hypothalamic paraventricular nucleus modulate cardiac component of the baroreflex in unanesthetized rats

In the present study, we investigated the role played by the hypothalamic paraventricular nucleus (PVN) in the modulation of cardiac baroreflex activity in unanesthetized rats. Bilateral microinjections of the nonselective neurotransmission blocker CoCl(2) into the PVN decreased the reflex bradycardic response evoked by blood pressure increases, but had no effect on reflex tachycardia evoked by blood pressure decreases. Bilateral microinjections of the selective NMDA glutamate receptor antagonist LY235959 into the PVN caused effects that were similar to those observed after microinjections of CoCl(2), decreasing reflex bradycardia without affecting tachycardic response. The microinjection of the selective non-NMDA glutamate receptor antagonist NBQX into the PVN did not affect the baroreflex activity. Also, the microinjection of L-glutamate into the PVN increased the reflex bradycardia, an effect opposed to that observed after PVN treatment with CoCl(2) or LY235959, and this effect of L-glutamate was blocked by PVN pretreatment with LY235959. LY235959 injected into the PVN after iv. treatment with the selective beta(1)-adrenoceptor antagonist atenolol still decreased the reflex bradycardia. Taken together, our results suggest a facilitatory influence of the PVN on the bradycardic response of the baroreflex through activation of local NMDA glutamate receptors and a modulation of the cardiac parasympathetic activity. (C) 2010 Elsevier Ireland Ltd and the Japan Neuroscience Society. All rights reserved.

Non-N-methyl-d-aspartate glutamate receptors in the lateral hypothalamus modulate cardiac baroreflex responses in conscious rats

P>In the present study, we investigated the effects of inhibition of the lateral hypothalamus (LH) neurotransmission with bilateral microinjection of CoCl(2), a non-selective blocker of neurotransmission, on modulation of cardiac baroreflex responses in conscious rats as well as the involvement of LH glutamatergic neurotransmission in this modulation. Reflex bradycardiac and tachycardiac responses to blood pressure increases (following i.v. infusion of phenylephrine) or decreases (following i.v. infusion of sodium nitroprusside) were investigated in conscious male Wistar rats. Responses were evaluated before and after microinjection of 1 nmol/100 nL CoCl(2), 2 nmol/100 nL 1,2,3,4-tetrahydro-6-nitro-2,3-dioxobenzoquinoxaline-7-sulphonamide (NBQX; a selective non-N-methyl-d-aspartate (NMDA) glutamate receptor antagonist) or different doses (2, 4 or 8 nmol/100 nL) of the selective NMDA glutamate receptor antagonist LY235959. Microinjection of CoCl(2) into the LH had no effect on the tachycardiac baroreflex response, but did evoke a decrease in the reflex bradycardia caused by increases in blood pressure. Microinjection of NBQX into the LH had a similar effect on reflex bradycardia as CoCl(2), but had no effect on the tachycardiac response. Microinjection of increasing doses of LY235959 into the LH had no effect on the cardiac baroreflex response. In conclusion, the data suggest that the LH has a tonic facilitatory influence on the parasympathetic component of the baroreflex. The results also indicate that this facilitatory influence is mediated by local LH glutamatergic neurotransmission through non-NMDA glutamatergic receptors.

Involvement of hypothalamic paraventricular nucleus non-N-methyl-d-aspartate receptors in the pressor response to noradrenaline microinjected into the bed nucleus of the stria terminalis of unanesthetized rats

Microinjection of noradrenaline into the bed nucleus of the stria terminalis (BST) has been reported to cause a pressor response in unanesthetized rats, which was shown to be mediated by acute vasopressin release into the systemic circulation. In the present study we verified the involvement of magnocellular neurons of the hypothalamic paraventricular (PVN) or supraoptic (SON) nuclei and the local neurotransmitter involved in the pressor response to noradrenaline microinjection into the BST. The PVN pretreatment with the non-selective neurotransmission blocker CoCl(2) (1 nmol/100 nL) inhibited the noradrenaline-evoked pressor response. However, responses were not affected by SON treatment with CoCl(2). Further experiments were carried out to test if glutamatergic neurotransmission in the PVN mediates the pressor response evoked by noradrenaline microinjection into the BST. Pretreatment of the PVN with the selective N-methyl-d-aspartate (NMDA) receptor antagonist LY235959 (2 nmol/100 nL) did not affect the noradrenaline-evoked pressor response. However, PVN pretreatment with the selective non-NMDA receptor antagonist NBQX (2 nmol/100 nL) significantly reduced the pressor response to noradrenaline microinjection into the BST. In conclusion, our results suggest that pressor responses to noradrenaline microinjection into the BST are mediated by PVN magnocellular neurons without involvement of SON neurons. They also suggest that a glutamatergic neurotransmission through non-NMDA glutamate receptors in the PVN mediates the response.

Anti-N-Methyl-D-Aspartate (NMDA) Receptor Encephalitis Mimicking a Primary Psychiatric Disorder in an Adolescent.

Anti-N-methyl-d-aspartate (anti-NMDA) receptor encephalitis likely has a wider clinical spectrum than previously recognized. This article reports a previously healthy 16-year-old girl who was diagnosed with anti-NMDA receptor encephalitis 3 months after onset of severe depression with psychotic features. She had no neurological manifestations, and cerebral magnetic resonance imaging (MRI) was normal. Slow background on electroencephalogram and an oligoclonal band in the cerebrospinal fluid prompted the search for anti-NMDA receptor antibodies. She markedly improved over time but remained with mild neuropsychological sequelae after a trial of late immunotherapy. Only a high index of suspicion enables recognition of the milder forms of the disease masquerading as primary psychiatric disorders.

The effect of the N-methyl-D-aspartate receptor antagonist dextromethorphan on perioperative brain injury in children undergoing cardiac surgery with cardiopulmonary bypass: results of a pilot study.

Experimental evidence indicates a role of the N-methyl-D-aspartate receptor in the pathogenesis of brain injury occurring during cardiac surgery with cardiopulmonary bypass (CPB). Dextromethorphan is a noncompetitive antagonist of this receptor with a favorable safety profile. Thirteen children age 3-36 months undergoing cardiac surgery with expected CPB of 60 minutes or more were randomly assigned to treatment with dextromethorphan (36-38 mg/kg/day) or placebo administered by naso-gastric tube. Dextromethorphan was absorbed well and reached putative therapeutic levels in blood and cerebrospinal fluid. Adverse effects were not observed. Mild hemiparesis developed after operation in one child of each group, and severe encephalopathy in one of the placebo group. Sharp waves were recorded in postoperative continuous electroencephalography in all placebo (n = 7) but only in 2/6 dextromethorphan treated children (p = 0.02). Pre- and postoperative cranial magnetic resonance imaging (MRI) revealed less pronounced ventricular enlargement in the dextromethorphan group (not significant). An increase of periventricular white matter lesions was visible in two placebo-treated children only. No elevations of cerebrospinal fluid enzymes were observed in either group. Although children with dextromethorphan showed less abnormalities in electroencephalography and MRI, dissimilarities of the treatment groups by chance diminished conclusions to possible protective effects of dextromethorphan at this time.

Severe childhood encephalopathy with dyskinesia and prolonged cognitive disturbances: evidence for anti-N-methyl-d-aspartate receptor encephalitis.

Aim We report four cases of acquired severe encephalopathy with massive hyperkinesia, marked neurological and cognitive regression, sleep disturbance, prolonged mutism, and a remarkably delayed recovery (time to full recovery between 5 and 18mo) with an overall good outcome, and its association with anti-N-methyl-d-aspartate (anti-NMDA) receptor antibodies. Method We reviewed the four cases retrospectively and we also reviewed the literature. Results Anti-NMDA receptor antibodies (without ovarian teratoma detected so far) were found in the two children tested in this study. Interpretation The clinical features are similar to those first reported in 1992 by Sebire et al.,(1) and rarely recognized since. Sleep disturbance was not emphasized as part of the disorder, but appears to be an important feature, whereas coma is less certain and difficult to evaluate in this setting. The combination of symptoms, evolution (mainly seizures at onset), severity, paucity of abnormal laboratory findings, very slow recovery, and difficult management justify its recognition as a specific entity. The neuropathological substrate may be anatomically close to that involved in encephalitis lethargica, in which the same target functions (sleep and movement) are affected but in reverse, with hypersomnolence and bradykinesia. This syndrome closely resembles anti-NMDA receptor encephalitis, which has been reported in adults and is often paraneoplastic.

Inhibitory effects of (2S, 3S)-3-[3-[4-(trifluoromethyl)benzoylamino]benzyloxy]aspartate (TFB-TBOA) on the astrocytic sodium responses to glutamate.

Astrocytes are responsible for the majority of the clearance of extracellular glutamate released during neuronal activity. dl-threo-beta-benzyloxyaspartate (TBOA) is extensively used as inhibitor of glutamate transport activity, but suffers from relatively low affinity for the transporter. Here, we characterized the effects of (2S, 3S)-3-[3-[4-(trifluoromethyl)benzoylamino]benzyloxy]aspartate (TFB-TBOA), a recently developed inhibitor of the glutamate transporter on mouse cortical astrocytes in primary culture. The glial Na(+)-glutamate transport system is very efficient and its activation by glutamate causes rapid intracellular Na(+) concentration (Na(+)(i)) changes that enable real time monitoring of transporter activity. Na(+)(i) was monitored by fluorescence microscopy in single astrocytes using the fluorescent Na(+)-sensitive probe sodium-binding benzofuran isophtalate. When applied alone, TFB-TBOA, at a concentration of 1 muM, caused small alterations of Na(+)(i). TFB-TBOA inhibited the Na(+)(i) response evoked by 200 muM glutamate in a concentration-dependent manner with IC(50) value of 43+/-9 nM, as measured on the amplitude of the Na(+)(i) response. The maximum inhibition of glutamate-evoked Na(+)(i) increase by TFB-TBOA was >80%, but was only partly reversible. The residual response persisted in the presence of the AMPA/kainate receptor antagonist CNQX. TFB-TBOA also efficiently inhibited Na(+)(i) elevations caused by the application of d-aspartate, a transporter substrate that does not activate non-NMDA ionotropic receptors. TFB-TBOA was found not to influence the membrane properties of cultured cortical neurons recorded in whole-cell patch clamp. Thus, TFB-TBOA, with its high potency and its apparent lack of neuronal effects, appears to be one of the most useful pharmacological tools available so far for studying glial glutamate transporters.