Brain neurotransmitters in glycine encephalopathy

Transurethral resection of the prostate syndrome: almost gone but not forgotten

Transurethral resection of the prostate (TURP) syndrome is a rare but potentially fatal syndrome with multifactorial pathophysiology that is now better understood. Unfortunately, despite this improved understanding, it is not yet obsolete and still remains a risk. Many reviews of TURP syndrome have been presented from an anesthetic perspective; this review reflects more the urologic perspective with emphasis on the importance of multidisciplinary management of this complex syndrome. We present a review of TURP syndrome that specifically assesses advances in the understanding of risk factors, pathophysiology, and techniques used to prevent this syndrome. The databases Medline, Embase, Cochrane Controlled Trial Register, and Database of Abstracts of Reviews of Effects were systematically reviewed from inception to April 2009 for the keywords TUR (P), TUR (P) syndrome, and transurethral resection of prostate. There was no language restriction for our search. Randomized controlled trials, review articles and case series were included in our search. Our review showed a declining trend in the incidence of TURP syndrome despite TURP remaining the gold standard for the management of benign prostatic obstruction. Technologic advances using an array of laser techniques, the use of bipolar circuitry, together with advances in training techniques have helped minimize the risk of development of this syndrome. This review demonstrates the complexity of TURP syndrome. Even with a greater understanding of the pathophysiology, it highlights the unpredictability of the syndrome from presenting symptoms, preventative measures, and management. TURP syndrome cannot be protocol driven and the need for vigilance, a high index of suspicion, intensive monitoring, and a multidisciplinary approach is vital.

Analysis of cholinergic markers, biogenic amines, and amino acids in the CNS of two APP overexpression mouse models

Two transgenic mouse models expressing mutated human amyloid precursor protein and previously found to display cognitive and behavioural alterations, reminiscent of Alzheimer patients' symptomatology, were scrutinised for putative brain region-specific changes in neurochemical parameters. Brains of NSE-hAPP751m-57, APP23 and wild-type mice were microdissected to perform brain region-specific neurochemical analyses. Impairment of cholinergic transmission, the prominent neurochemical deficit in Alzheimer brain, was examined; acetylcholinesterase and choline acetyltransferase activity levels were determined as markers of the cholinergic system. Since Alzheimer neurodegeneration is not restricted to the cholinergic system, brain levels of biogenic amines and metabolites, and amino acidergic neurotransmitters and systemic amino acids were analysed as well. Cholinergic dysfunction, reflected in reduced enzymatic activity in the basal forebrain nuclei, was restricted to the APP23 model, which also exhibited more outspoken and more widespread changes in other neurotransmitter systems. Significant changes in compounds of the noradrenergic and serotonergic system were observed, as well as alterations in levels of the inhibitory neurotransmitter glycine and systemic amino acids. These observations were clearly in occurrence with the more pronounced histopathological and behavioural phenotype of the APP23 model. As transgenic models often do not represent an end-stage of the disease, some discrepancies with results from post-mortem human Alzheimer brain analyses were apparent; in particular, no significant alterations in excitatory amino acid levels were detected. Our findings of brain region-specific alterations in compound levels indicate disturbed neurotransmission pathways, and greatly add to the validity of APP23 mice as a model for Alzheimer's disease. Transgenic mouse models may be employed as a tool to study early-stage neurochemical changes, which are often not accessible in Alzheimer brain.

One-methyl group metabolism in non-ketotic hyperglycinaemia: mildly elevated cerebrospinal fluid homocysteine levels

Non-ketotic hyperglycinaemia (NKH) is a rare, severe brain disease caused by deficient glycine cleavage enzyme complex activity resulting in elevated glycine concentrations. Recent experience suggests that factors in addition to glycine kinetics are involved in its pathogenesis. The glycine cleavage reaction through the formation of methylenetetrahydrofolate is an important one-methyl group donor. A deficiency in one-methyl group metabolites, in particular of choline, has been hypothesized in NKH. We investigated metabolites involved in one-methyl group metabolism in plasma and CSF of 8 patients with NKH, and monitored the effect of treatment with choline in one patient. Plasma and CSF choline and phosphatidylcholine concentrations were normal, except for a low plasma choline in the single neonate studied. Choline treatment did not change brain choline content, and was not associated with clinical or radiological improvement. Methionine concentrations and, in one-patient, S-adenosylmethionine and 5-methyltetrahydrofolate concentrations were normal in CSF. Homocysteine concentrations in CSF, however, were slightly but consistently elevated in all four patients examined, but cysteine, cysteinylglycine and glutathione were normal. Serine is important in the transfer of one-methyl groups from mitochondria to cytosol. Serine concentrations were normal in plasma and CSF, but dropped to below normal in CSF in three patients on benzoate treatment. These observations add to our understanding of the complex metabolic disturbances in NKH.

Spongy encephalopathy in ketotic hyperglycinemia

Three cases of ketotic hyperglycinemia are described. Spongy encephalopathy was present in white as well as gray matter. The cell type that predominantly exhibited swelling was the astrocyte. Glycine binding is required for activation of the NMDA receptor. By constant excitation a surplus of glycine could disturb the ion balance. This might provide the pathogenetic principle of seizures and cytotoxic edema in hyperglycinemia.

Neonatal glycine encephalopathy: biochemical and neuropathologic findings

A patient with neonatal glycine encephalopathy who had severe neurologic retardation, spasticity, and seizures died at 17 years of age. Glycine concentration was markedly elevated in brain tissue, especially in the cerebellum. Neuropathologic study revealed spongy myelinopathy throughout the central nervous system and calcium oxalate crystals in the cerebellum, which are probably derived from degradation of glycine. Myelinopathy appeared to be static compared to neonatal patients. The neurologic manifestations of neonatal glycine encephalopathy are probably due to neurotransmitter abnormalities, not to myelin damage.

Changes in amino acid contents in the spinal cord and brainstem of rats with experimental autoimmune encephalomyelitis

The effects of experimental autoimmune encephalomyelitis (attack and recovery) on levels of six amino acids have been investigated in nine regions of the Lewis rat spinal cord between segments C3 and Co1 and in the brainstem. Amino acids were analyzed by separation of their 4'-dimethylaminoazobenzene-4-sulfonyl chloride derivatives on a reversed-phase column using a ternary gradient. Glutamate and gamma-aminobutyric acid were reduced by 10-30% in all segments during the attack, whereas taurine, lysine, glutamine, and glycine were all greatly increased (up to 300%). Most values except those of taurine, as well as glutamate in certain segments, returned to normal on recovery. Because some of these compounds have neurotransmitter function, these changes may contribute to the neurological symptoms of experimental autoimmune encephalomyelitis.

[3H]glycine binding sites, NMDA and PCP receptors have similar distributions in the human hippocampus: an autoradiographic study

The distribution of [3H]glycine binding sites was compared with that of N-methyl-D-aspartate (NMDA) receptors labelled with L-[3H]glutamate, and with that of phencyclidine (PCP) receptors labelled with [3H]1-(1-(2-thienyl)-cyclohexyl)piperidine ([3H]TCP) in sections from 7 normal human hippocampi. The results indicate that strychnine-insensitive glycine binding sites are present in high concentrations in CA1 and the molecular layer of the dentate gyrus. This distribution is very similar to the distributions of NMDA and PCP receptors in the human hippocampus.