The effect of arachidonic acid on the M current of NG108-15 neuroblastoma × glioma hybrid cells

The M current, I _M, a voltage-dependent non-inactivating K⁺ current, was recorded in NG108-15 neuroblastoma × glioma hybrid cells, using the whole-cell mode of the patch-clamp technique. We studied the effect of arachidonic acid, other fatty acids and inhibitors of the arachidonic acid metabolism. In relatively high concentrations (25–50 M) arachidonic acid first increased and later decreased the current, I _h, which holds the membrane potential at –30 mV and mainly flows through open M channels. It shifted the midpoint potential, V _o, of the relation between M conductance, g _M, and membrane potential, V, to more negative values and decreased the maximum conductance ¯g _M and the time constant _M. In smaller concentrations (5–10 M) arachidonic acid merely decreased I _h and ¯g _M with little effect on V _o and _M. Eicosatetraynoic acid and docosa-hexaenoic acid acted similarly to arachidonic acid whereas stearic acid had no effect. Of the three enzyme inhibitors studied, nordihydroguaiaretic acid acted similarly to arachidonic acid. i. e. caused a biphasic change in I _h. Indomethacin and quinacrine caused, respectively, a pure increase and a pure decrease of I _h and ¯g _M. Possible explanations are build-up of internally produced arachidonic acid, depletion of eicosanoid products or an inhibitory effect unrelated to arachidonic acid metabolism.     

Effects of ageing on the content in sulfur-containing amino acids in rat brain

Summary Concentrations of the sulfur-containing amino acids methionine, homocysteic acid, cysteic acid and taurine were measured in brain structures of young and old Wistar rats in an attempt to etablish a possible link between the increase in oxidative stress with ageing and changes in tissue levels of these amino acids. Contrary to data reported by others, in all brain structures of young and old rats homocysteic acid levels could not be quantified. Compared with young rats, in old animals taurine and methionine concentrations significantly decreased in striatum and cortex; decreased taurine levels were also found in nucleus accumbens and cerebellum and lower concentrations of methionine were found in midbrain, hippocampus and pons-medulla. Cysteic acid levels either did not change or significantly increased in cortex and hippocampus. These results are discussed taking into account the biosynthesis of sulfur-containing amino acids in rat brain and the decrease in glutathione in relation to oxidative stress with ageing.Changes in aspartic acid, glutamic acid, serine, glutamine, glycine and GABA concentrations with ageing were also determined in the same brain structures and were in good agreement with those previously reportedAbbreviations H ₂O₂ hydrogen peroxide - MAO monoamine oxidase - GSHP glutathione peroxidase - PAPS 3-phosphoadenosine-5-phosphosulfate - OPA O-phthaldialdehyde - HPLC high performance liquid chromatography - Asp aspartic acid - CA cysteic acid - CSA cysteine sulfinic acid - Cys cysteine - GABA -aminobutyric acid - Gln glutamine - Glu glutamic acid - Gly glycine - HCA homocysteic acid - Met methionine - Ser serine - Tau taurine     

Excitatory Connections Between CA1 Pyramidal Cells Revealed by Spike Triggered Averaging in Slices of Rat Hippocampus are Partially NMDA Receptor Mediated

Spike triggered averaging was used to record local circuit connections between pairs of CA1 pyramidal neurons in isolated slices of rat hippocampus. Of 795 pairs of neurons tested, six were connected. These epsps were only partially blocked by 2-amino-5-phosphonovalerate (AP-5), which decreased the amplitude and half width of the epsp, but did not affect the early rising phase. In contrast, 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) blocked all phases of the epsp and combinations of AP-5 and CNQX blocked the epsp almost entirely. These results indicate that these epsps were mediated by both N-methyl-d-aspartate (NMDA) and non-NMDA excitatory amino acid receptors. Moreover, they exhibited a voltage relation typical of neuronal responses to NMDA, increasing in amplitude and duration as the postsynaptic cell was depolarized. These epsps were brief (10 - 90% rise time < 5 ms, width at half amplitude < 20 ms), indicating a proximal location. Increasing presynaptic firing rate (1 - 4 spikes/s) reduced average epsp amplitude by almost 50%. When epsps were evoked by pairs of spikes (interval 3 - 25 ms), a large response to the first spike precluded a large response to the second. No evidence for selective enhancement of the NMDA receptor component by paired spike activation was found. It is concluded that a significant NMDA receptor mediated input to CA1 is provided by local circuit CA1 - CA1 connections and that these synapses can be demonstrated under control conditions.     

Sensory Excitatory Postsynaptic Potentials Mediated by NMDA and non-NMDA Receptors in the Thalamus in vivo

Excitatory amino acid neurotransmitters, such as l-glutamate, act at several receptors in the brain, which are sometimes referred to as N-methyl-d-aspartate (NMDA) and non-NMDA receptors. Extensive in vitro work indicates that both NMDA receptors and non-NMDA receptors contribute to excitatory postsynaptic potentials (epsps). The contribution of NMDA receptors to epsps in vivo under physiological conditions is, however, almost unknown. The receptors that mediate the epsps evoked in thalamic relay cells by natural stimulation of sensory afferents have been investigated in anaesthetized rats, and we report the first pharmacological characterization of an excitatory amino acid receptor-mediated epsp in vivo involving both non-NMDA receptors and, in particular, NMDA receptors.     

Adrenomyeloneuropathy

Summary Adrenomyeloneuropathy (AMN) is reported in two kindreds. In the first family, four male patients were affected: two adults with the full clinical picture but with a different chronology of the main symptoms, a third adult with central nervous system involvement and a child who died early with adrenal insufficiency. The second family included two male patients with AMN, one adult with raised ACTH levels and his nephew with normal adrenal function. Two other young males died with adrenoleukodystrophy (ALD), one being subjected to a postmortem study.Clinical, endocrinological, neurophysiological and pathological studies were performed.The following conclusions can be made: (1) AMN and ALD are closely related entities; (2) there exists a considerable intrafamilial variability of the clinical picture; (3) AMN is to be included in the differential diagnosis of myelopathies and, conversely, signs of central nervous system damage must be sought in male patients with adrenal insufficiency; (4) electron microscopy of nerve twigs brings supportive diagnostic evidence pending the more widespread determination of the C26/C22 fatty acids ratios in cultured fibroblasts or plasma.This paper has been financially supported by the Fonds voor Geneeskundig Wetenschappelijk Onderzoek (grant no. 3.0004.81) and by the Baron Charles Bracht Foundation     

比色法测定消癌平注射液中总酚酸的含量

目的　建立消癌平注射液中总酚酸的含量测定方法。方法　以绿原酸为对照品 ,比色法测定。结果　绿原酸回归方程为A =35 8.1 4×C - 5 .3879(r=0 .9993,n =9)。在 2 0 .5～ 32 8μg范围内呈线性关系 ,平均回收率为 1 0 0 .4 8% ,RSD =1 .70 %。结论　所用方法简便、准确、快速 ,可作为该制剂的定量方法     

小儿先天性胆管扩张症囊肿内胆汁酸盐的LC-MS/MS分析

目的 探讨小儿先天性胆管扩张症囊肿内胆汁中胆汁酸谱的特点及其意义.方法 通过建立人类已知的全部15种胆汁酸改良的液相色谱串联质谱定量检测方法 ,以我院2002年10月至2004年6月收治小儿先天性胆管扩张症(CBD)16例为研究对象,其中男11例,女5例,年龄11～134个月,平均(44.8±24.6)个月,术前B超和(或)CT、术中胆道造影确诊为先天性胆管扩张症.对16例先天性胆管扩张症囊肿内胆汁进行胆汁酸定量检测.结果 先天性胆管扩张症囊肿内总胆汁酸的浓度与对照组比较明显降低,组成胆汁酸谱的各种胆汁酸与对照组比较相应减少,未见致癌性胆酸浓度增高.儿童胆汁中甘氨熊脱氧胆酸含量较高,总胆汁酸的降低与肝纤维化程度呈正相关.结论 先天性胆管扩张症患儿存在胆汁酸代谢异常,可能与肝脏继发性损伤程度有关,异常的胆汁酸谱可能与胆结石的发生相关.     

非诺贝特和辛伐他汀对酒精性脂肪肝血清游离脂肪酸谱的影响

目的　研究非诺贝特和辛伐他汀对酒精性脂肪肝大鼠模型血清游离脂肪酸谱的影响。方法　以酒精灌胃加橄榄油饮食的方法建立酒精性脂肪肝大鼠模型 ,模型组分为非诺贝特治疗组 (80mg·kg-1)、辛伐他汀治疗组 (4mg·kg-1)以及未治疗组。 4wk后处死大鼠 ,用气相色谱方法测定血清游离脂肪酸谱。结果　非诺贝特治疗组明显改善由乙醇引起的血清多不饱和脂肪酸的降低 [油酸 :(38 2 12± 7 788) μg·L-1vs (31 6 2 0± 6 14 2 ) μg·L-1,亚油酸 :(37 2 6 9± 8 0 6 5 ) μg·L-1vs (30 2 5 4± 9 0 6 3) μg·L-1,花生四烯酸 :(11 6 4 6±2 6 0 1) μg·L-1vs (9 0 12± 1 2 36 ) μg·L-1) ;同时肝脏病理改善。辛伐他汀治疗组则加重血清多不饱和脂肪酸的降低 ,并使饱和脂肪酸增加。结论　非诺贝特和辛伐他汀对酒精性脂肪肝血清游离脂肪酸谱作用不同 ;血清多不饱和脂肪酸在酒精性脂肪肝的发病机制以及治疗反应中可能起着重要的作用     

A toxicokinetic model of malathion and its metabolites as a tool to assess human exposure and risk through measurements of urinary biomarkers.

A toxicokinetic model is proposed to predict the time evolution of malathion and its metabolites, mono- and dicarboxylic acids (MCA, DCA) and phosphoric derivatives (dimethyl dithiophosphate [DMDTP], dimethyl thiophosphate [DMTP], and dimethyl phosphate [DMP]) in the human body and excreta, under a variety of exposure routes and scenarios. The biological determinants of the kinetics were established from published data on the in vivo time profiles of malathion and its metabolites in the blood and urine of human volunteers exposed by intravenous, oral, or dermal routes. In the model, body and excreta compartments were used to represent the time varying amounts of each of the following: malathion, MCA, DCA, DMDTP, DMTP, and DMP. The dynamic of intercompartment exchanges was described mathematically by a differential equation system that ensured conservation of mass at all times. The model parameters were determined by statistically adjusting the explicit solution of the differential equations to the experimental human data. Simulations provide a close approximation to kinetic data available in the published literature. When simulating a dermal exposure to malathion, the main route of entry for workers, the model predicts that it takes an average of 11.8 h to recover half of the absorbed dose of malathion eventually excreted in urine as metabolites, compared to 3.2 h following an intravenous injection and 4.0 h after oral administration. This shows that following a dermal exposure, the absorption rate governs the urinary excretion rate of malathion metabolites because the dermal absorption rate is much slower than biotransformation and renal clearance processes. The model served to establish biological reference values for malathion metabolites in urine since it allows links to be made between the absorbed dose of malathion and the time course of cumulative amounts of metabolites excreted in urine. From the no-observed-effect level (NOEL) of 0.61 micromol/kg/day derived from the data of Moeller and Rider (1962), the model predicts corresponding biological reference values for MCA, DCA, and phosphoric derivatives of 44, 13, and 62 nmol/kg, respectively, in 24-h urine samples. The latter were used to assess the health risk of workers exposed to malathion in botanical greenhouses, starting from urinary measurements of MCA and DCA metabolites.     

Effect of iontophoresis and fatty acids on permeation of Arginine Vasopressin through rat skin

The aim of this study was to assess the effects of fatty acids and iontophoretic mode of penetration enhancement on transdermal delivery of Arginine Vasopressin (AVP). Sprague-Dawley (SD) rat skin was pretreated with fatty acids (e.g. 5% w/v, lauric acid, oleic acid, and linoleic acid in ethanol:water (EtOH:W, 2:1 system) for 2h and iontophoresis in vitro, separately or together. The results indicate that all fatty acids studied increased (P<0.05) the flux of AVP in comparison to control (not pretreated with enhancer) and their effectiveness in flux enhancement was comparable. Further, oleic acid in combination with iontophoresis significantly increased the permeation of AVP both in comparison to pretreatment with fatty acids and iontophoresis alone. However, iontophoresis did not further increase the permeation of AVP through linoleic acid pretreated skin. Fourier transform infrared (FT-IR) spectroscopic studies revealed that EtOH:W (2:1) system is not effective in lipid extraction. The shift to higher wavenumbers of the symmetric and asymmetric stretching peaks at 2850 and 2920cm(-1) revealed that at the concentration used, oleic acid and linoleic acid caused fluidization of stratum corneum (SC) lipids. This study provides direct evidence that oleic acid in EtOH:W (2:1) system causes disruption of the SC lipid lamellae and that a combination of oleic acid with iontophoresis further enhances the effects of oleic acid in a synergistic manner.