Insight into epileptic and physiological déjà vu: from a multicentric cohort study.

BACKGROUND AND PURPOSE: The presence of a continuum between physiological déjà vu (DV) and epileptic DV is still not known as well as epidemiological data in the Italian population. The aim was to identify the epidemiological distribution of DV in Italy, and secondly to look for specific features of DV able to discriminate between epileptic and non-epileptic DV. METHODS: In all, 1000 individuals, 543 healthy controls (C) (313 women; age 40 ± 15 years) and 457 patients with epilepsy (E) (260 women; age 39 ± 14 years), were prospectively recruited from 10 outpatient neurological clinics throughout Italy. All populations were screened using the Italian Inventory for Déjà Vu Experiences Assessment (I-IDEA) test and E and pairwise C underwent a comprehensive epilepsy interview. RESULTS: Of E, 69% stated that they experienced 'recognition' and 13.2% reported that this feeling occurred from a few times a month to at least weekly (versus 7.7% of the control group). Furthermore, a greater percentage of E (6.8% vs. 2.2%) reported that from a few times a month to at least weekly they felt that it seemed as though everything around was not real. In E, the feeling of recognition raised fright (22.3% vs. 13.2%) and a sense of oppression (19.4% vs. 9.4%). A fifth of E felt recognition during epileptic seizures. CONCLUSION: Only E regardless of aetiology firmly answered that they had the feeling of recognition during an epileptic seizure; thus question 14 of the I-IDEA test part 2 discriminated E from C. Paranormal activity, remembering dreams and travel frequency were mostly correlated to DV in E suggesting that the visual-memory network might be involved in epileptic DV.

Vagal Nerve Stimulation for Drug-Resistant Epilepsy: Adverse Events and Outcome in a Series of Patients with Long-Term Follow-Up.

BACKGROUND: Vagal nerve stimulation (VNS) is a palliative treatment option for drug-resistant epilepsy. The aim of this study was to describe the clinical and demographic features of selected patients scheduled for VNS and to evaluate the long-term efficacy of VNS in seizure control. MATERIALS AND METHODS: Between 2006 and 2013, 32 consecutive epileptic patients (14 male and 18 female) were enrolled at our Institute for VNS implantation. In all cases resective surgery had previously been excluded by the use of a noninvasive presurgical study protocol. Mean age was 32 years (range 18-50), and mean epilepsy duration 23 years (range 11-39). All subjects were followed-up for at least 2 years (mean 6 years, range 2-9) after VNS implantation. Patients were considered responders when a reduction of seizures of more than 50 % was reported. RESULTS: All patients had complex partial seizures, in 81 % of the patients with secondary generalization and in 56 % with drop attacks. Neurological examination revealed focal deficits in 19 % of the patients. Brain magnetic resonance imaging (MRI) was positive in 47 % of the patients. No surgical complications were observed in this series. Three patients were lost to follow-up. Twelve patients were classified as responders. Among the others, 1 patient experienced side effects (snoring and groaning during sleep) and the device was removed. CONCLUSIONS: Our data confirm that VNS is a safe procedure and a valid palliative treatment option for drug-resistant epileptic patients not suitable for resective surgery.

Rufinamide in refractory childhood epileptic encephalopathies other than Lennox-Gastaut syndrome.

BACKGROUND: To report on the first multicenter Italian experience with rufinamide as adjunctive drug in children, adolescents and young adults with refractory childhood-onset epileptic encephalopathies other than Lennox-Gastaut syndrome. METHODS: Thirty-eight patients (19 males, 19 females), aged between 4 and 34 (mean 13.7 ± 8.3, median 12.5), all affected by different types of childhood-onset refractory epileptic encephalopathies other than Lennox-Gastaut syndrome, were treated with rufinamide as adjunctive drug for a mean period of 11.4 months (range 3-26 months). RESULTS: Fifteen of 38 patients (39.5%) had a ≥ 50% seizure reduction in countable seizures. Complete seizure freedom was achieved in one of these patients (2.6%). Three patients (7.9%) had a 25-49% seizure reduction, whilst seizure frequency remained unchanged in 15 (39.5%) and increased in five patients (13.1%). Eleven patients (28.9%) reported adverse side effects. Vomiting was reported in five patients (13.1%); drowsiness, decreased appetite and irritability with migraine manifested in other four patients. They were transient and mild in all cases. CONCLUSION: Rufinamide may be an effective and well-tolerated adjunctive drug for the treatment of refractory childhood-onset epileptic encephalopathies other than Lennox-Gastaut syndrome. Rufinamide was most effective in patients with drop-attacks and (bi)frontal spike-wave discharges.

Valproic acid and phenobarbital blood levels during the first month of treatment with the ketogenic diet.

OBJECTIVE: The aim of this study was to assess how the ketogenic diet influences the blood levels of antiepileptic drugs in the first month of treatment in a pediatric population with drug-resistant epilepsy. METHODS: The plasma concentrations of antiepileptic drugs were investigated in an open study on 36 consecutive children and adolescents (20 males), aged between 6 months and 16 years (mean age 4.7 years), who were put on the ketogenic diet because of medically refractory epilepsy. The plasma levels of antiepileptic drugs were determined 30 days and immediately before the diet and on days 8, 15, 22 and 29 after the start of the diet. The daily dose of each drug was not changed during the first month of treatment, while the daily dose of benzodiazepines was reduced by up to 30% if excessive sedation or drowsiness occurred. RESULTS: While plasma concentrations of phenobarbital did not change in the first month on the ketogenic diet (mean increase of 2.3 mg/l ± 1.0), valproic acid showed a slight but not significant decrease (mean decrease of 6.7 mg/l ± 3.2), 2 weeks after the start of the diet. CONCLUSIONS: Adjustments in the daily dose of either drug before the start of the diet do not however appear to be justified.

A case of epilepsia partialis continua of abdominal muscles after brain tumor surgery.

Epilepsia partialis continua (EPC) is a rare form of focal motor status epilepticus characterized by continuous muscular twitches or jerks involving a limited part of the body, usually facial region and distal limb. Although the cerebrovascular disease is known to be one of the most common causes of this condition, other reported cases with predominant abdominal involvement have different aetiologies, including, tumors, focal cortical dysplasia, and central nervous system infections. No cases of epilepsia partialis continua of the abdominal wall occurred after brain surgery have been previously reported. We describe the clinical, electrophysiological, and neuroimaging findings in an adult patient presenting with persistent unilateral abdominal myoclonus configuring an EPC as the evolution of a super-refractory hemibody convulsive status epilepticus, occurred after brain tumor surgery.

Precursor ion discovery on a hybrid quadrupole-time-of-flight mass spectrometer for gonadotropin-releasing hormone detection in complex biological mixtures.

The gonadotropin-releasing hormone (GnRH) family includes several hypophysiotropic peptides occupying a central position in the regulatory loop controlling reproduction. Studies are still under way to clarify its biological role and evolutionary implication. Although sequencing of multiple genomes is bringing further advances in the understanding of the evolution of GnRH, there is still a need for biochemical studies aiming to identify GnRH from different species. Using a hybrid quadrupole-time-of-flight (Q-TOF) instrument, a new method for selective and sensitive GnRH detection and characterization from tissue extracts has been developed. The method uses the "precursor ion discovery" mode based on the capability of the Q-TOF analyzer to quickly record alternate mass spectra at low and high collision energy of precursor and product ion spectra, respectively, following liquid chromatographic separation of complex biological mixtures. The method exploits the selective detection of a specific b(2) product ion at m/z 249.1, corresponding to the N-terminus dipeptide pyroglutamic acid-histidine, highly conserved among nearly all species (22 of 24), and deriving from the preferential fragmentation of GnRHs carrying the dipeptide. Importantly, the method also includes acquisition of the product ion spectra from any candidate precursor ion, thereby allowing the determination of sequence information to confirm the GnRH identity or to isolate new ones.

Subacute cerebellar ataxia as presenting symptom of systemic lupus erythematosus.

Neuropsychiatric manifestations are commonly observed in systemic lupus erythematosus (SLE) patients. In particular, neurological involvement is known to be more common in patients with positive anticardiolipin antibodies and lupus anticoagulants. Nevertheless, cerebellar ataxia has rarely been reported, especially as the first clinical manifestation of this systemic autoimmune disorder. Cerebral vascular infarction or ischemia, vasogenic oedema and antibody-mediated cerebral vasculopathy or vasculitic process have been supposed as possible aetiologies of acute cerebellar ataxia related to SLE. We report the clinical and radiological features of a woman who developed a rapidly progressive cerebellar syndrome as first sign of SLE; no other cause explaining her cerebellar ataxia was found. The patient improved after high-dose steroids. The appearance of a cerebellar syndrome with unknown aetiology with associated features of possible systemic autoimmune dysfunction, should be taken into account in clinical practice for appropriate diagnostic workup in order to provide effective therapeutic options.

D-aspartate and reproductive activity in sheep.

D-aspartic acid (D-Asp) has been isolated from neuroendocrine tissues of many invertebrates and vertebrates. Recently, it has been demonstrated that this D-amino acid may be converted to N-methyl-D-aspartic acid (NMDA), a neuromodulator associated with sexual activity. In this study, we determined D-Asp and NMDA concentrations in endocrine glands and other tissues in ewes after D-Asp administration and in controls. We also evaluated the effects of d-Asp administration on the reproductive activity of ewes by determining either progesterone concentrations or LH pulses in the presence or absence of estradiol benzoate. The pineal gland showed the highest natural content of D-Asp (1.47+/-0.22 micromol/g tissue), whereas the pituitary gland had the highest capability to store d-Asp, with a peak value (9.7+/-0.81 micromol/g tissue) 6 h after its administration. NMDA increased sharply 12 h following D-Asp administration, reaching values three times higher than the baseline in both the pituitary and brain. D-Asp was quickly adsorbed after subcutaneous administration, with a peak in plasma levels 2 h after administration and a return to baseline values after 6 h. D-Asp administration achieved a significant (P < 0.001) increase in LH values with respect to estradiol or estradiol + D-Asp treatments. d-Asp treatment once or twice a week did not successfully drive acyclic ewes into reproductive activity. In conclusion, the results obtained in this study demonstrated that D-Asp is endogenously present in sheep tissues and electively stored in endocrine glands and brain after its administration. NMDA and LH increase following D-Asp administration suggesting a role of this D-amino acid in the reproductive activity of sheep.

Total hydrolysis of proteins with strongly reduced racemization of amino acids.

A new method has been devised for the complete hydrolysis of proteins with an extremely low level of racemization of amino acids. Proteins are incubated in 10 M HCl at a low temperature to obtain partial hydrolysis. They are then incubated with pronase and finally with leucine aminopeptidase and peptidyl-D-amino-acid hydrolase from Loligo vulgaris. The proposed method ensures the total hydrolysis of either purified proteins or proteins contained in a crude homogenate of animal or vegetable tissue. In both cases, the racemization of amino acids (expressed as rate of D form/D + L form X 100) was lower than 0.015% for aspartic acid and lower than 0.01% for other amino acids. D-Amino acids released from peptides or proteins were estimated with enzymatic methods based on the use of octopus D-aspartate oxidase or hog kidney D-amino acid oxidase; with these enzymes, 0.05 nmol of a D-amino acid was determined in the presence of up to 20 mumols of a mixture of L-amino acids (ratio %D/D + L = 0.00025). The method allows the determination of D-amino acids either in tissues in which they are present in high concentrations (as human cataract lenses, tooth enamel, etc.) or in those with low enantiomer content (as brain, erythrocytes, etc.). Using the method described, we hydrolyzed several synthetic peptides consisting of D- and L-amino acids and determined the amount of D-amino acids. In addition, we totally hydrolyzed all the nuclear proteins of human cataractous lenses. The amount of D-aspartic acid was 0.026 mumols/mg in lenses of women aged between 71 and 76 years and 0.0256 mumols/mg in lenses of men aged between 55 and 72 years. The D-aspartic acid measured corresponds to about 12% with respect to total aspartic acid.

Hatching enzyme from the sea-squirt Ciona intestinalis: purification and properties.

We have purified a 34 kDa hatching enzyme from the water in which the embryos of the sea-squirt Ciona intestinalis hatch. This enzyme was obtained in homogeneous form as judged from SDS-PAGE and HPLC gel filtration. The enzyme possesses proteolytic activity and is able to digest the chorion of the egg of C. intestinalis. It is a metalloproteinase and contains one atom of Zn per molecule. The optimum pH is 8.5. The enzyme shows hydrolytic activity towards the -CO-NH- bonds, which are hydrolyzed by the members of the serine proteinase family. It has a trypsin-like activity in that it cuts the bond of Arg and Lys at P1 position of the scissile bond -P1-P1', but it differs from trypsin insofar as it hydrolyzes the peptide bond on either side of Arg and Lys. The purified enzyme is inhibited by the common metal-chelators and by the classical trypsin proteinase inhibitors. The apparent K(m) values at 37 degrees C and pH 8.5 toward tosyl-Gly-Pro-Arg-NHNap, tosyl-Gly-Pro-Lys-NHNap and Bz-Arg-Gly-Arg-NHNap were 0.125, 0.5 and 2.5 mM, respectively. The results obtained in this study suggest that the hatching enzyme from C. intestinalis exhibits both trypsin-like activity and metalloproteinase activity.

Properties of the flavoenzyme D-aspartate oxidase from Octopus vulgaris.

The properties of D-aspartate oxidase from Octopus vulgaris (EC 1.4.3.1) have been investigated. The protein is a monomer of M(r) 37,000 containing one mol flavin/mol protein. The enzyme as isolated exists at least in two forms, one containing FAD and the other, which is catalytically inactive, probably containing 6-OH-FAD, as inferred from the absorption spectrum of the enzyme. An additional form of the enzyme, as far as the nature of the coenzyme is concerned, has been detected in the purified enzyme and shown to derive from the form originally containing FAD. The modulation of the coenzyme reactivity exerted by Octopus D-aspartate oxidase, as studied by spectrophotometric techniques, conforms to the one expected for an enzyme belonging to the oxidase class of flavoproteins. Structural investigations show similarities in both the amino-acid composition and the N-terminal amino-acid sequence to bovine D-aspartate oxidase and porcine D-amino-acid oxidase. In summary, the general properties of the enzyme from Octopus vulgaris closely resemble those of the enzyme from beef kidney. Moreover, kinetic analyses suggest that two active-site residues with pKa of 7.1 and 9.1 are critical for catalysis, and that the ionization of such residues has different effects on the catalytic activity depending whether mono- or dicarboxylic D-amino acids are used as substrate.

Palmitoylethanolamide reduces pain-related behaviors and restores glutamatergic synapses homeostasis in the medial prefrontal cortex of neuropathic mice.

BACKGROUND: Enhanced supraspinal glutamate levels following nerve injury are associated with pathophysiological mechanisms responsible for neuropathic pain. Chronic pain can interfere with specific brain areas involved in glutamate-dependent neuropsychological processes, such as cognition, memory, and decision-making. The medial prefrontal cortex (mPFC) is thought to play a critical role in pain-related depression and anxiety, which are frequent co-morbidities of chronic pain. Using an animal model of spared nerve injury (SNI) of the sciatic nerve, we assess bio-molecular modifications in glutamatergic synapses in the mPFC that underlie neuropathic pain-induced plastic changes at 30 days post-surgery. Moreover, we examine the effects of palmitoylethanolamide (PEA) administration on pain-related behaviours, as well as the cortical biochemical and morphological changes that occur in SNI animals. RESULTS: At 1 month, SNI was associated with mechanical and thermal hypersensitivity, as well as depression-like behaviour, cognitive impairments, and obsessive-compulsive activities. Moreover, we observed an overall glutamate synapse modification in the mPFC, characterized by changes in synaptic density proteins and amino acid levels. Finally, with regard to the resolution of pain and depressive-like syndrome in SNI mice, PEA restored the glutamatergic synapse proteins and changes in amino acid release. CONCLUSIONS: Given the potential role of the mPFC in pain mechanisms, our findings may provide novel insights into neuropathic pain forebrain processes and indicate PEA as a new pharmacological tool to treat neuropathic pain and the related negative affective states. Graphical Abstract Palmitoylethanolamide: a new pharmacological tool to treat neuropathic pain and the related negative affective states.

The role of D-aspartic acid and N-methyl-D-aspartic acid in the regulation of prolactin release.

In this study, using an enzymatic HPLC method in combination with D-aspartate oxidase, we show that N-methyl-D-aspartate (NMDA) is present at nanomolar levels in rat nervous system and endocrine glands as a natural compound, and it is biosynthesized in vivo and in vitro. D-aspartate (D-Asp) is its natural precursor and also occurs as an endogenous compound. Among the endocrine glands, the highest quantities of D-Asp (78 +/- 12 nmol/g) and NMDA (8.4 +/- 1.2 nmol/g) occur in the adenohypophysis, whereas the hypothalamus represents the area of the nervous system where these amino acids are most abundant (55 +/- 9 and 5.6 +/- 1.1 nmol/g for D-Asp and NMDA, respectively). When D-Asp is administered to rats by ip injection, there is a significant uptake of D-Asp into the adenohypophysis and a significant increase in the concentration of NMDA in the adenohypophysis, hypothalamus and hippocampus, suggesting that D-Asp is an endogenous precursor for NMDA biosynthesis. Experiments conducted on tissue homogenates confirm that D-Asp is the precursor of the NMDA and that the enzyme catalyzing this reaction is a methyltransferase. S-adenosyl-L-methionine (SAM) is the methyl group donor. In vivo experiments consisting of ip injections of sodium D-aspartate show that this amino acid induced a significant serum PRL elevation and this effect is dose and time dependent. In vitro experiments conducted on isolated adenohypophysis or adenohypophysis coincubated with the hypothalamus, showed that the release of PRL is caused by a direct action of D-Asp on the pituitary gland and also mediated by the indirect action of NMDA on the hypothalamus. Then, the latter induces the release of a putative factor that in turn stimulates the adenohypophysis reinforcing the PRL release. In conclusion, our data suggest that D-Asp and NMDA are present endogenously in the rat and are involved in the modulation of PRL release.

Secretion of D-aspartic acid by the rat testis and its role in endocrinology of the testis and spermatogenesis.

The D-isomer of aspartic acid (D-Asp) has been found in rat testes. In the present study, samples of testicular venous blood plasma, rete testis fluid, interstitial extracellular fluid, luminal fluid from the seminiferous tubules, testicular parenchymal cells, epididymal spermatozoa and peripheral blood plasma were collected and analyzed for D-Asp by two methods, an enzymatic and a chromatographic HPLC method. The two methods gave very similar results for all samples. The highest concentrations of D-Asp (about 120 nmol/ml) were found in testicular venous blood plasma, with slightly lower concentrations in rete testis fluid (95 nmol/ml) and epididymal spermatozoa (80 nmol/g wet weight). Lower levels were found in testicular parenchymal cells (which would comprise mostly spermatids and spermatocytes), luminal fluid from the seminiferous tubules and interstitial extracellular fluid (26, 23 and 11 nmol/ml respectively). However, these values were all higher than those for peripheral blood plasma (6 nmol/ml). It would appear that D-Asp is being secreted by the testis mostly into the venous blood, passing thence into the rete testis fluid and being incorporated into the spermatozoa at the time or after they leave the testis. The distribution of D-Asp is thus quite different from that of testosterone, and its role and the reason for its high concentration in the male reproductive tract remain to be elucidated.

D-aspartate disposition in neuronal and endocrine tissues: ontogeny, biosynthesis and release.

High levels of D-aspartate occur in the brain and endocrine glands, such as pineal, adrenal and pituitary. In the brain, D-aspartate levels are highest in embryonic and early postnatal stages. Notably high levels occur in the early postnatal cortical plate and subventricular zone of the cerebral cortical cultures, implying a role in development. In embryonic neuronal primary culture cells, we detected high levels of endogenous D-aspartate and demonstrated biosynthesis of [14C]D-aspartate using [14C]L-aspartate as precursor. Synthesis of D-aspartate in cell cultures is inhibited by amino-oxyacetic acid, an inhibitor of pyridoxal phosphate-dependent enzymes. In the rat adrenal medulla, D-aspartate is depleted by treatment of the animals with intraperitoneal nicotine injections. In adrenal slices, D-aspartate is released by depolarization with KCl or acetylcholine, implying physiological release by activation of the cholinergic innervation of the adrenal. Our characterization of D-aspartate ontogeny, biosynthesis and depolarization-induced release implies specific physiological roles for this amino acid.

D-aspartic acid is implicated in the control of testosterone production by the vertebrate gonad. Studies on the female green frog, Rana esculenta.

In the present study we report the occurrence of D-aspartic acid (D-Asp) in the ovary of the green frog Rana esculenta and its putative involvement in testosterone production by the gonad. In the ovary, D-Asp concentrations undergo significant variations during the main phases of the sexual cycle. In spawning females (March), its concentration was low (2.5 +/- 1.1 nmol/g ovary) and during the post-reproductive period (June) it increased and reached its peak level (58.0 +/- 10.1 nmol/g) in October. In that month, vitellogenesis occurs in a new set of ovarian follicles and continues until the next spring. The concentrations of D-Asp in the ovary and of testosterone in the ovary and in the plasma were inversely correlated during the reproductive cycle: when endogenous D-Asp was low (March), testosterone was high (36.9 +/- 4.8 ng/g ovary; 23.1 +/- 2.76 ng/ml plasma) and, in contrast, when the D-Asp concentration was high (October), the testosterone concentration was low (0.86 +/- 0.21 ng/g ovary and 5.0 +/- 1.3 ng/ml plasma). In vivo experiments, consisting of injection of D-Asp (2.0 mumol/g body weight) into the dorsal lymphatic sac of adult female frogs, demonstrated that this amino acid accumulates significantly in the ovary. After 3 h, moreover, it caused a decrease in testosterone level in the plasma of about 80%. This inhibition was reversible: within 18 h after the amino acid injection, as the D-Asp concentration in the ovary decreased, the testosterone titre was restored in both ovary and plasma. In vitro experiments, conducted in isolated ovarian follicles, confirmed this phenomenon and identified these gonadal components as the putative D-Asp targets. Other amino acids (L-Asp, D-Glu, L-Glu, D-Ala and L-Ala) used instead of D-Asp were ineffective. These findings indicate that D-Asp is involved in the control of androgen secretion by the ovary in this amphibian species, revealing a more complex system for control of this androgen synthesis than was previously believed to exist.

The purification and characterization of alpha-L-fucosidase from the hepatopancreas of Octopus vulgaris.

We have isolated and purified, by affinity chromatography with Agarose-epsilon-amino-caproyl-fucosamine, an alpha-L-fucosidase [alpha-L-fucoside fucohydrolase EC 3.2.1.51] from the hepatopancreas of Octopus vulgaris. In the purified fraction only fucosidase activity could be detected. However, two protein bands, one major (about 95 per cent) and one minor (about 5 per cent), were evident on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Isoelectric focusing also revealed two activities, pI 8.1 (major) and pI 7.3 (minor). Under denaturing conditions the molecular weight of the major band was estimated to be 52,000 while that of the minor one was 43,000. Only one major activity peak with an apparent molecular weight of 70,000--75,000 was detected by gel filtration chromatography. The enzyme has two optimal pH values, and the relative activities are temperature-dependent; one optimum is at pH 5.5 +/- 0.2 and the other at pH 3.0 +/- 0.2. We found that the enzyme has a maximum activity at about 70 degrees C, but 50 per cent of the enzyme was inactivated at 70 degrees C after 5 min. The purified enzyme, using p-nitrophenyl-L-fucoside as substrate, has a specific activity of 38.9 units/mg of protein, Km of 3.58 x 10(-4) M and Vmax of 65 mumol/min/mg of protein. alpha-L-Fucose acts as a competitive inhibitor, with a K1 of 1.2 x 10(-3) M. alpha-L-Fucosidase released radioactive fucose from cellular glycopeptides, but no detectable free fucose was released fom 5 natural substrates.

Presence of D-alanine in proteins of normal and Alzheimer human brain.

This report constitutes the first demonstration of the presence of D-alanine in the proteins of the human nervous system. Proteins of the frontal lobe white and gray matter of human brains, both normal and Alzheimer subjects, contain D-alanine at concentrations between 0.50 and 1.28 mumol/g of wet tissue, 50-70-times lower than the concentration of L-alanine. Both white and gray matter of Alzheimer brains contain D-alanine 1.4-times higher than the respective regions of normal brains. The gray matter proteins of Alzheimer brains show a highly significant 8% decrease in total alanine content, when compared with normal brain gray matter proteins. Since Alzheimer's disease is exhibited by deterioration of the gray matter, the occurrence of elevated D-alanine levels in the gray matter of Alzheimer brains is a significant discovery and raises the question whether this enantiomer causes the degeneration of the gray matter proteins in Alzheimer's disease, or whether it is an effect of the disease.

Quantification of D-aspartate in normal and Alzheimer brains.

Using a new procedure to hydrolyze proteins without provoking racemization of the amino acids and using enzymatic methods to determine D- and L-aspartate (Asp), we have quantified the content of protein-bound D-aspartate (both D-aspartic acid and D-asparagine) of human brain white and gray matter proteins from normal and Alzheimer subjects. The D-enantiomer is present in brain proteins at mean concentrations between 0.48 and 0.90 mumol/g of wet tissue, corresponding to concentrations 34-82 times lower than that of L-aspartate. The highest levels of D-aspartate were found in Alzheimer gray matter (0.60-0.90, mean 0.69 mumol/g of wet tissue). When expressed as the percentage of total (i.e. D- plus L-) aspartate, %D = [D/(D + L)] x 100, the Alzheimer brains show a significantly higher content of D-aspartate in both gray matter (2.08%) and white matter (1.80%) than in the corresponding tissues of normal brains (1.65% in gray, 1.58% in white).