Intestinal release and uptake of phenolic antioxidant diferulic acids

Diferulic acids are potent antioxidants and are abundant structural components of plant cell walls, especially in cereal brans. As such, they are part of many human and animal diets and may contribute to the beneficial effect of cereal brans on health. However, these phenolics are ester-linked to cell wall polysaccharides and cannot be absorbed in this form. This study provides the first evidence that diferulic acids can be absorbed via the gastrointestinal tract. The 5-5-, 8-O-4-, and 8-5-diferulic acids were identified in the plasma of rats after oral dosing with a mixture of the three acids in oil. Our study also reveals that human and rat colonic microflora contain esterase activity able to release 5-5-, 8-O-4-, and 8-5-diferulic acids from model compounds and dietary cereal brans, hence providing a mechanism for release of dietary diferulates prior to absorption of the free acids. In addition, cell-free extracts from human and rat small intestine mucosa exhibited esterase activity towards diferulate esters. Hence, we have shown that esterified diferulates can be released from cereal brans by intestinal enzymes, and that free diferulic acids can be absorbed and enter the circulatory system. Our results suggest that the phenolic antioxidant diferulic acids are bioavailable.

Esterase activity able to hydrolyze dietary antioxidant hydroxycinnamates is distributed along the intestine of mammals

Hydroxycinnamic acids are effective antioxidants and are abundant components of plant cell walls, especially in cereal bran. For example, wheat and rye brans are rich sources of the hydroxycinnamates ferulic acid, sinapic acid, and p-coumaric acid. These phenolics are part of human and animal diets and may contribute to the beneficial effects derived from consumption of cereal bran. However, these compounds are ester linked to the main polymers in the plant cell wall and cannot be absorbed in this complex form. The present work shows that esterases with activity toward esters of the major dietary hydroxycinnamates are distributed throughout the intestinal tract of mammals. In rats, the cinnamoyl esterase activity in the small intestine is derived mainly from the mucosa, whereas in the large intestine the esterase activity was found predominantly in the luminal microflora. Mucosa cell-free extracts obtained from human duodenum, jejunum, and ileum efficiently hydrolyzed various hydroxycinnamoyl esters, providing the first evidence of human cinnamoyl esterase(s). This study first demonstrates the release by human colonic esterase(s) (mostly of microbial origin) of sinapic acid and p-coumaric acid from rye and wheat brans. Hydrolysis by intestinal esterase(s) is very likely the major route for release of antioxidant hydroxycinnamic acids in vivo.

Antioxidant effects of phenolic rye (Secale cereale L.) extracts, monomeric hydroxycinnamates, and ferulic acid dehydrodimers on human low-density lipoproteins

Dietary antioxidants that protect low-density lipoprotein (LDL) from oxidation may help to prevent atherosclerosis and coronary heart disease. The antioxidant activities of purified monomeric and dimeric hydroxycinnamates and of phenolic extracts from rye (whole grain, bran, and flour) were investigated using an in vitro copper-catalyzed human LDL oxidation assay. The most abundant ferulic acid dehydrodimer (diFA) found in rye, 8-O-4-diFA, was a slightly better antioxidant than ferulic acid and p-coumaric acid. The antioxidant activity of the 8-5-diFA was comparable to that of ferulic acid, but neither 5-5-diFA nor 8-5-benzofuran-diFA inhibited LDL oxidation when added at 10-40 microM. The antioxidant activity of the monomeric hydroxycinnamates decreased in the following order: caffeic acid > sinapic acid > ferulic acid > p-coumaric acid. The antioxidant activity of rye extracts was significantly correlated with their total content of monomeric and dimeric hydroxycinnamates, and the rye bran extract was the most potent. The data suggest that especially rye bran provides a source of dietary phenolic antioxidants that may have potential health effects.

Effects of new non-N-methyl-D-aspartate antagonists on synaptic transmission in the in vitro rat hippocampus

1. The effects of new, potent non-N-methyl-D-aspartate (NMDA) receptor antagonists, 6,7-dinitroquinoxaline-2,3-dione (DNQX) and 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX), have been examined using intra- and extracellular recordings in the hippocampal slice preparation. In terms of potency and selectivity, the action of the two blockers was similar and CNQX was used in most experiments. 2. CNQX reduced the responses to ionophoretic applications of the non-NMDA agonists kainate (KAI) and quisqualate (QUIS) with IC50 values of 1.2 and 4.8 microM, respectively. In Mg2+-free solutions responses to NMDA were generally not affected by concentrations of CNQX up to 25 microM. 3. The action of CNQX was only slowly and poorly reversible on washing. Responses to QUIS and KAI were also reversibly reduced by ionophoretic application of CNQX. 4. CNQX blocked the evoked EPSP in CA1 and CA3 neurones with an IC50 of around 2 microM, which is similar to the IC50 for responses to KAI. CNQX was without effect on the passive membrane properties, the afferent volley and paired pulse potentiation. 5. In the presence of CNQX (greater than 5 microM) a small EPSP remained which was largest in CA1 neurones. It was blocked by low concentrations of the NMDA receptor antagonist (+/-)-2-amino-5-phosphonovaleric acid (APV), was markedly enhanced on removing Mg2+ ions from the bathing medium and, in voltage-clamp experiments, showed a potential dependence which is characteristic of the NMDA ionophore. 6. The latency of the APV-sensitive EPSP in CA1 was the same as the CNQX-sensitive EPSP, indicating that NMDA receptors participate in monosynaptic excitation. 7. Feedback and feed-forward inhibition in both area CA1 and CA3 were sensitive to CNQX. There seemed to be two components of the inhibition, both of which appear to be GABAergic since they could be blocked by picrotoxin (PTX), but only one of which was blocked by CNQX. The CNQX-resistant IPSP was not affected by APV. 8. In conclusion, quinoxalinediones have been used to demonstrate that non-NMDA receptors mediate the majority of the EPSP. Additionally, a component of the EPSP in CA1 is mediated by NMDA receptors and is manifested at resting membrane potentials and in the presence of Mg2+.

Content of phenolic acids and ferulic acid dehydrodimers in 17 rye (Secale cereale L.) varieties

The contents of pnenolic acids and ferulic acid dehydrodimers were quantified by HPLC analysis after alkaline hydrolysis in kernels of 17 rye (Secale cereale L.) varieties grown in one location in Denmark during 1997 and 1998. Significant variations (P < 0.05) with regard to the concentration of the analyzed components were observed among the different rye varieties and also between different harvest years. However, the content of phenolic acids in the analyzed rye varieties was narrow compared to cereals such as wheat and barley. The concentration of ferulic acid, the most abundant phenolic acid ranged from 900 to 1170 microgram g(-1) dry matter. The content in sinapic acid ranged from 70 to 140 microgram g(-1) dry matter, p-coumaric acid ranged from 40 to 70 microgram g(-1) dry matter, and caffeic, p-hydroxybenzoic, protocatechuic, and vanillic acids were all detected in concentrations less than 20 microgram g(-1) dry matter. The most abundant ferulic acid dehydrodimer 8-O-4 -DiFA was quantified in concentrations from 130 to 200 microgram g(-1) dry matter followed by 8,5 -DiFA benzofuran form (50-100 microgram g(-1) dry matter), 5,5 -DiFA (40-70 microgram g(-1) dry matter), and 8,5 -DiFA (20-40 microgram g(-1) dry matter).

Regenerative properties of pyramidal cell dendrites in area CA1 of the rat hippocampus

1. Intracellular recordings were obtained from 184 distal apical dendrites and twenty-six somata of CA1 pyramidal neurones in the rat hippocampal slice preparation. In the presence of 3.25 mM K+ 200 ms suprathreshold current pulses evoked three different types of firing patterns in the apical dendrites, all of which were distinct from regular somatic firing. Fast tetrodotoxin (TTX)-sensitive spiking was evoked in 38.8% of the dendrites. Compound spiking, consisting of an initial fast spike followed by one or more secondary slow spikes of variable amplitude and duration, was seen in 44.1% of dendrites. 'Classical' burst firing, resembling intrinsic somatic bursts, was evoked in 17.1% of the dendrites. 2. In fast spiking dendrites, the spikes evoked by long depolarizing pulses were rarely overshooting, showed prominent accommodation and declined progressively to about one-third of the initial amplitude. The amplitude of single dendritic fast spikes (50.6 +/- 1.5 mV; mean +/- S.E.M.) was smaller than that of somatic spikes (82.2 +/- 1.9 mV) and their rate of rise (81.3 +/- 4.3 V s-1) was markedly slower than that of somatic spikes (291.5 +/- 17.8 V s-1). However, the thresholds were not significantly different (dendrites, -49.8 +/- 0.8 mV; somata, -50.8 +/- 1.3 mV). These results indicate that fast spikes in the distal parts of apical dendrites are generated by a local regenerative Na+ current. 3. 4-Aminopyridine (4-AP, 0.1-0.5 mM) caused a dose-dependent slowing of the repolarization of the fast spikes, while tetraethylammonium (TEA, 2 mM) and Co2+ (2 mM) induced a slowing of the late phase of the repolarization. These results indicate that the transient outward K+ current, IA, and the Ca(2+)-activated K+ current, IC, are involved in the repolarization of dendritic Na(+)-dependent spikes. 4. Compound spiking was completely blocked by TTX (0.5-1 microM). The secondary slow spikes within the complex were blocked by Co2+ (2 mM), nifedipine (10 microM) and high concentrations (> 50 microM) of verapamil, while Ni2+ (100-300 microM) had no effect. Thus, compound spiking consists of an initial Na(+)-dependent spike followed by one or more slow Ca(2+)-dependent spikes mediated by L-type Ca2+ channels located in the apical dendrites. 5. In fast spiking dendrites, 4-AP (0.5-2.5 mM) changed the firing pattern from regular fast spiking to compound spiking. In the presence of 4-AP (0.1-0.5 mM), the single fast spike evoked by a short (20 ms), threshold current pulse, was followed by secondary slow spikes of variable amplitude and duration.(ABSTRACT TRUNCATED AT 400 WORDS)

Paired-pulse facilitation in the dentate gyrus: a patch-clamp study in rat hippocampus in vitro

1. Whole-cell patch-clamp recordings were used to study paired-pulse facilitation (PPF) of the lateral perforant path input to the dentate gyrus in thin hippocampal slices. 2. Orthodromic stimulation of the lateral perforant pathway evoked a excitatory postsynaptic current (EPSC) with a latency of 3.3 +/- 0.1 ms (mean +/- SE) that fluctuated in amplitude. The EPSC had a rise time (10-90%) of 2.79 +/- 0.06 ms (n = 35) and decayed with a single exponential time course with a time-constant of 9.14 +/- 0.24 ms (n = 35). No correlation was found between the amplitude of the EPSC and the rise time or decay time-constant. The non-N-methyl-D-aspartate (NMDA) antagonist 6-cyano-7-nitroquinoxaline-2,3-dione completely blocked the EPSC whereas the NMDA antagonist D-aminophosphonovaleric acid (APV) had modest effects. 3. When a test (T-)EPSC was preceded at an interval of 100 ms by a conditioning (C-)EPSC, a significant increase in the amplitude of the T-EPSC was seen in 38 out of 44 trials analyzed from a total of 27 granule cells. The average amount of PPF was 35.7 +/- 2.1%. There was no apparent correlation between the amount of PPF and the stimulation intensity or mean amplitude of the C-EPSC. The time course of the facilitated T-EPSC was not significantly different from that of the C-EPSC. 4. No correlation was found between the amplitude of the C-EPSC and that of the T-EPSC. Estimates of quantal content (mcv) were determined by calculating the ratio of the squared averaged EPSC amplitude (from 48 responses) to the variance of these responses (M2/sigma 2) whereas quantal amplitudes (qcv) were estimated by calculating the ratio of the response variance to average EPSC amplitude (sigma 2/M). PPF was found to be associated with an average increase in mcv of 64.8 +/- 7.2% (n = 38) whereas qcv was decreased by 12.1 +/- 3.8%. 5. The time course of PPF was studied by varying the interval between the C- and T-pulse from 10 to 400 ms while keeping the stimulation intensity constant. Maximal facilitation of the T-EPSC was obtained with interpulse intervals < or = 25 ms where the average facilitation amounted to approximately 70% (n = 6). The decline of facilitation was nearly exponential and was no longer evident with intervals > 350 ms.(ABSTRACT TRUNCATED AT 400 WORDS)

Somatic amplification of distally generated subthreshold EPSPs in rat hippocampal pyramidal neurones

1. Intracellular recordings from hippocampal CA1 pyramidal neurones revealed that EPSPs evoked by selective stimulation of the isolated afferent input to the distal third of the apical dendrites were relatively insensitive to changes in dendritic membrane potential (Vm) but amplified by depolarizations of the somatic Vm. The amplification was present at potentials depolarized from resting membrane potential (RMP) but was most marked when the EPSPs were close to threshold for action potential generation. The amplification consisted of a uniform component and a variable component which was only present when the EPSPs were threshold straddling. 2. The somatic amplification was caused by an intrinsic membrane current which was blocked by somatic application of tetrodotoxin (TTX, 10 microM), but was insensitive to bath application of NiCl2 (100-200 microM). We therefore suggest that the amplification of the subthreshold EPSP is due primarily to the activation of a non-inactivating Na+ current (INaP). 3. Injection of 4-aminopyridine (4-AP, 25-50 mM) during intradendritic recordings resulted in amplification of the EPSPs in 37% of the dendrites, which was similar to that observed in somatic recordings. However, in the one case in which somatic application of TTX was tested, dendritic amplification was blocked, suggesting that it is a reflection of the somatic amplification. 4. Because the shift to variable amplification was very abrupt and it is present in only a very narrow voltage range close to threshold, we suggest that the variable component is caused by the regenerative activation of INaP. The variability itself is probably due to the simultaneous activation of different outward K+ currents. 5. The present results indicate that the somatic region of CA1 pyramidal neurones can function as a voltage-dependent amplifier of distally evoked EPSPs and that this is due to the activation of a somatic INaP. The presence of this amplifying mechanism will have important functional consequences for the way in which distally generated EPSPs are integrated.

An Actinobacillus pleuropneumoniae PCR typing system based on the apx and omlA genes--evaluation of isolates from lungs and tonsils of pigs

The genetic variability of a gene coding for an outer membrane lipoprotein (omlA) was used to develop a PCR typing system for Actinobacillus pleuropneumoniae. Sequence differences in the middle region of the gene divided the A. pleuropneumoniae serotypes in five distinct groups. Group I included serotypes 1, 9, 11 and 12 (omlA l), Group II consisted of serotypes 2 and 8 (omlA II), Group III included serotypes 3, 6 and 7 (omlA III), Group IV (omlA IV) consisted of serotype 4 and Group V of serotypes 5a, 5b and 10 (omlA V). The sequence differences were utilized to construct PCR primers specific for each group, except of Group IV, as the amplicon of serotype 4 could be separated from Group III by size. Together with a PCR apx typing system, the omlA PCR typing system could discriminate the majority of A. pleuropneumoniae serotypes of biovar 1 except of serotypes 1, 9 and 11 and serotypes 2 and 8. The PCR typing system was tested on 102 field strains of A. pleuropneumoniae isolated from lungs of diseased pigs. The serotyping results of the investigated field strains were in agreement with the apx and omlA gene patterns found in the reference strains of the bacteria, with the exception of the omlA gene of five strains of serotype 8. To examine the apx and omlA gene pattern of tonsil isolates, the PCR typing system was tested on a total of 280 A. pleuropneumoniae field strains isolated from tonsils of pigs. Agreement between serotyping and DNA typing was found in 96% of the isolates using the apx gene patterns and in 89% of the isolates using the omlA gene. The same serotype specific apx/omlA gene pattern was thus found in the majority of the tonsil isolates and in isolates from diseased lungs. Most of the differences in the omlA gene were found in 18 tonsil isolates of serotype 12. The omlA/apx PCR typing system described in the present study makes it possible to determine the type specificity of the majority of A. pleuropneumoniae isolates by simple PCR technique and enables phenotype independent characterization of isolates non-typable by serotyping.

Factors determining the efficacy of distal excitatory synapses in rat hippocampal CA1 pyramidal neurones

1. A new preparation of the in vitro rat hippocampal slice has been developed in which the synaptic input to the distal apical dendrites of CA1 pyramidal neurones is isolated. This has been used to investigate the properties of distally evoked synaptic potentials. 2. Distal paired-pulse stimulation (0.1 Hz) evoked a dendritic response consisting of a pair of EPSPs, which showed facilitation. The first EPSP had a rise time (10-90%) of 2.2 +/- 0.05 ms and a half-width of 9.1 +/- 0.13 ms. The EPSPs were greatly reduced by CNQX (10 microM) and the remaining component could be enhanced in Mg(2+)-free Ringer solution and blocked by AP5 (50 microM). In 70% of the dendrites, the EPSPs were followed by a prolonged after-hyperpolarization (AHP) which could be blocked by a selective and potent GABAB antagonist, CGP55845A (2 microM). These results indicate that the EPSPs are primarily mediated by non-NMDA receptors with a small contribution from NMDA receptors, whereas the AHP is a GABAB receptor-mediated slow IPSP. 3. With intrasomatic recordings, the rise time of proximally generated EPSPs (3.4 +/- 0.1 ms) was half that of distally generated EPSPs (6.7 +/- 0.5 ms), whereas the half-widths were similar (19.6 +/- 0.8 ms and 23.8 +/- 1 ms, respectively). These results indicate that propagation through the proximal apical dendrites slows the time-to-peak of distally generated EPSPs. 4. Distal stimulation evoked spikes in 60% of pyramidal neurones. At threshold, the distally evoked spike always appeared on the decaying phase of the dendritic EPSP, indicating that the spike is initiated at some distance proximal to the dendritic recording site. Furthermore, distally and proximally generated threshold spikes had a similar voltage dependency. These results therefore suggest that distally generated threshold spikes are primarily initiated at the initial segment. 5. At threshold, spikes generated by stimulation of distal synapses arose from the decaying phase of the dendritic EPSPs with a latency determined by the time course of the EPSP at the spike initiation zone. With maximal stimulation, however, the spikes arose directly from the peak of the EPSPs with a time-to-spike similar to the time-to-peak of subthreshold dendritic EPSPs. Functionally, this means that the effect of dendritic propagation can be overcome by recruiting more synapses, thereby ensuring a faster response time to distal synaptic inputs. 6. In 42% of the neurones in which distal EPSPs evoked spikes, the relationship between EPSP amplitude and spike latency could be accounted for by a constant dendritic modulation of the EPSP. In the remaining 58%, the change in latency was greater than can be accounted for by a constant dendritic influence. This additional change in latency is best explained by a sudden shift in the spike initiation zone to the proximal dendrites. This would explain the delay observed between the action of somatic application of TTX (10 microM) on antidromically evoked spikes and distally evoked suprathreshold spikes. 7. The present results indicate that full compensation for the electrotonic properties of the main proximal dendrites is not achieved despite the presence of Na+ and Ca2+ currents. Nevertheless, distal excitatory synapses are capable of initiating spiking in most pyramidal neurones, and changes in EPSP amplitude can modulate the spike latency. Furthermore, even though the primary spike initiation zone is in the initial segment, the results suggest that it can move into the proximal apical dendrites under physiological conditions, which has the effect of further shortening the response time to distal excitatory synaptic inputs.

The excitability of CA1 pyramidal cell dendrites is modulated by a local Ca(2+)-dependent K(+)-conductance

Intracellular recordings are made from distal apical dendrites of CA1 pyramidal neurones in the rat hippocampal slice preparation. Injection of a threshold current evoked two predominant firing patterns: fast spiking and compound spiking. Suprathreshold current injection evoked high frequency dendritic spiking followed by a pronounced slow afterhyperpolarization (sAHP(dend)) lasting for several hundred milliseconds, during which spiking was inhibited for a variable period. In fast spiking dendrites, the size of the sAHP(dend) depended on the number and frequency of preceding spikes, whereas, in compound spiking dendrites, it was more closely related to the size and duration of preceding Ca(2+)-spikes. During the peak of the sAHP(dend), the membrane conductance was increased by 56%. The sAHP(dend) was blocked by perfusion with Ca2+ and by intradendritic injection of ethyleneglycol-bis-(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid (EGTA; 0.01 or 0.2 M), indicating that the activation of the sAHP(dend) depends on a rise in intradendritic Ca2+. The sAHP(dend) was also blocked by low concentrations (0.5-1 microM) of carbachol. The data presented here therefore, provide strong evidence that the sAHP(dend) is due to the activation of a local Ca(2+)-dependent K(+)-conductance. Possible implications of a dendritic Ca(2+)-dependent K(+)-conductance for the integration of synaptic potentials are discussed.

Local anesthetics block transient outward potassium currents in rat neocortical neurons

1. Whole-cell patch clamp techniques were used to record transient outward potassium currents in embryonic rat neocortical neurons maintained in culture. The effect of lidocaine and its quaternary derivative QX222 on this transient outward current (TOC) was examined. 2. Extracellular application of lidocaine produced a progressive decrease in peak TOC amplitude with no change in the overall current waveform. Peak amplitude was reduced to 74 +/- 6% (mean +/- SE) of control by 0.5 mM and to 48 +/- 2% by 2 mM lidocaine. The effect of lidocaine was fully reversible. Intracellular application of QX222 also resulted in a concentration-dependent reduction of the TOC with 0.5 mM reducing the peak amplitude to 73 +/- 8% of control and 1 mM reducing it to 41 +/- 4%. 3. Lidocaine reduced TOCs when applied intracellularly but the rate of block was considerably slower than with extracellular application. QX222 had no effect on the TOC when applied extracellularly. 4. Lidocaine (1 mM) induced a 4-5 mV hyperpolarizing shift in the voltage-dependence of activation and steady-state inactivation with no change in the slope factor. This small hyperpolarizing shift could not account for the > 30% reduction in peak amplitude produced by 1 mM lidocaine. Hyperpolarizing shifts were not seen with 0.5 mM intracellular QX222. The lack of effect on the slope of the activation and steady-state inactivation curves indicates that local anesthetic (LA) actions were not voltage-dependent. 5. Lidocaine or QX222 did not produce a significant change in the TOC decay time-constant. The lack of any significant change in the voltage-dependence of steady-state inactivation or time course of recovery from inactivation indicates that LAs were not altering inactivation mechanisms. 6. Application of lidocaine or QX222 during a 60-s period, when the TOC channels were kept in the resting state, reduced the peak amplitude of the first evoked TOC. The reduction was not as large as when TOCs were evoked at regular 0.1-Hz intervals during drug application. This indicates that the amount of tonic block induced by the LA is dependent on channel activation. Increasing the activation frequency to 1 Hz after a steady-state had been obtained with lidocaine or QX222 did not result in additional reductions in the TOC. 7. It is proposed that lidocaine and QX222 tonically block TOCs by binding to a site within the channel protein complex, rendering the channel non-conductive.(ABSTRACT TRUNCATED AT 400 WORDS)

Direct demonstration of an N-methyl-D-aspartate receptor mediated component of excitatory synaptic transmission in area CA1 of the rat hippocampus

The action of a new non-N-methyl-D-aspartate (NMDA) receptor antagonist, 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX), on synaptic transmission in area CA1 of the rat hippocampus has been examined. Intracellular and extracellular recordings showed CNQX to be a potent antagonist of synaptic potentials evoked by stimulation of the Schaffer collateral-commissural fibre system. One to 2 microM CNQX was sufficient to reduce the excitatory postsynaptic potential (EPSP) by 50%. CNQX is therefore about 100 times more potent than previously available non-NMDA receptor antagonists. In the presence of CNQX, a small depolarizing potential could still be evoked. This potential was sensitive to the NMDA-receptor blocker, 2-amino-5-phosphonovaleric acid (APV), increased in size on depolarizing the neurone and also increased in size on removing Mg2+ from the perfusing medium. This residual EPSP therefore has characteristics which are consistent with its mediation via the NMDA receptor-coupled ionophore. These results indicate a dual composition of the monosynaptic excitatory potential in area CA1.

A Metabolomics Study of Retrospective Forensic Data from Whole Blood Samples of Humans Exposed to 3,4-Methylenedioxymethamphetamine: A New Approach for Identifying Drug Metabolites and Changes in Metabolism Related to Drug Consumption

The illicit drug 3,4-methylenedioxymethamphetamine (MDMA) has profound physiological cerebral, cardiac, and hepatic effects that are reflected in the blood. Screening of blood for MDMA and other narcotics are routinely performed in forensics analysis using ultra-performance liquid chromatography with high-resolution time-of-flight mass spectrometry (UPLC-HR-TOFMS). The aim of this study was to investigate whether such UPLC-HR-TOFMS data collected over a two-year period could be used for untargeted metabolomics to determine MDMA metabolites as well as endogenous changes related to drug response and toxicology. Whole blood samples from living Danish drivers' positive for MDMA in different concentrations were compared to negative control samples using various statistical methods. The untargeted identification of known MDMA metabolites was used to validate the methods. The results further revealed changes of several acylcarnitines, adenosine monophosphate, adenosine, inosine, thiomorpholine 3-carboxylate, tryptophan, S-adenosyl-l-homocysteine (SAH), and lysophospatidylcholine (lysoPC) species in response to MDMA. These endogenous metabolites could be implicated in an increased energy demand and mechanisms related to the serotonergic syndrome as well as drug induced neurotoxicity. The findings showed that it was possible to extract meaningful results from retrospective UPLC-HR-TOFMS screening data for metabolic profiling in relation to drug metabolism, endogenous physiological effects, and toxicology.

Noradrenaline receptors participate in the regulation of GABAergic inhibition in area CA1 of the rat hippocampus

1. Standard intracellular recordings from CA1 pyramidal neurones in in vitro hippocampal slices have been used to investigate the effects of excitatory amino acid antagonists and adrenergic agents on evoked synaptic potentials. 2. Ortho- and antidromic stimulation were conducted with remotely placed electrodes in order to minimize the possibility of stimulating the interneurones directly. In addition to the excitatory postsynaptic potential (EPSP), orthodromic stimulation evoked an inhibitory sequence consisting of a fast and slow inhibitory postsynaptic potential (IPSP). The slow-IPSP was blocked by intracellular injection of QX 314. Antidromic stimulation evoked a relatively pure fast-IPSP. 3. In seven neurones the differential effects of glutamatergic receptor blockers on the fast-IPSP were investigated. The N-methyl-D-aspartate (NMDA) receptor blocker, DL-2-amino-5-phosphonovaleric acid (APV) was added after the full effect of the non-NMDA receptor blocker, 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) had been achieved. In three neurones, APV had no additional blocking effect, while in the remaining four neurones, both the ortho- and antidromically evoked IPSPs were reduced by 20-50%. This suggests that NMDA receptors participate in the activation of some GABAergic interneurones, which was further confirmed by showing that the IPSP was enhanced by Mg(2+)-free medium. 4. In the presence of CNQX (10 microM) and APV (50 microM) together, the ortho- and antidromically evoked fast-IPSPs were greatly reduced. A small 'residual' IPSP remained which was best studied by depolarizing the neurone to around -50 mV. With maximum stimulation, this amounted to 26.3 +/- 15.4% (mean +/- S.E.M., n = 15) of the control IPSP evoked by orthodromic stimulation and 41 +/- 14.6% of the control IPSP evoked by antidromic stimulation. The following statements apply equally to the ortho- and antidromically activated residual IPSPs. 5. The residual IPSP was completely blocked by low concentrations of bicuculline, indicating that it is mediated by GABAA receptors. When compared with a control IPSP of similar amplitude, the residual IPSP was found to have a faster rise time and time-to-peak, but a similar decay time. 6. Neither the muscarinic cholinergic antagonist, atropine nor the presynaptic glutamate agonist, L-2-amino-4-phosphonobutyric acid (L-APB) had any effect on the residual IPSP. 7. The residual IPSP was completely blocked by the adrenergic beta-receptor antagonist, L-propranolol (50-100 microM).(ABSTRACT TRUNCATED AT 400 WORDS)

Dendritic electrogenesis in rat hippocampal CA1 pyramidal neurons: functional aspects of Na+ and Ca2+ currents in apical dendrites

The regenerative properties of CA1 pyramidal neurons were studied through differential polarization with external electrical fields. Recordings were obtained from somata and apical dendrites in the presence of 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX), DL-2-amino-5-phosphonovaleric acid (APV), and bicuculline. S+ fields hyperpolarized the distal apical dendrites and depolarized the rest of the cell, whereas S divided by fields reversed the polarization. During intradendritic recordings, S+ fields evoked either fast spikes or compound spiking. The threshold response consisted of a low-amplitude fast spike and a slow depolarizing potential. At higher field intensities the slow depolarizing potential increased in amplitude, and additional spikes of high amplitude appeared. During intrasomatic recordings, S+ field evoked repetitive firing of fast spikes, whereas S divided by fields evoked a slow depolarizing potential on top of which high- and low-amplitude spikes were evoked. Tetrodotoxin (TTX) blocked all types of responses in both dendrites and somata. Perfusion with Ca(2+)-free, Co(2+)-containing medium increased the frequency and amplitude of fast spikes evoked by S+ field and substantially reduced the slow depolarizing potential evoked by S+ field and substantially reduced the slow depolarizing potential evoked by S divided by fields. Antidromic stimulation revealed that an all-or-none dendritic component was activated in the distal apical dendrites by back-propagating somatic spikes. The dendritic component had an absolute refractory period of about 4 ms and a relative refractory period of 10-12 ms. Ca(2+)-dependent spikes in the dendrites were followed by a long-lasting afterhyperpolarization (AHP) and a decrease in membrane input resistance, during which dendritic excitability was selectively reduced. The data suggest that generation of fast Na+ currents and slow Ca2+ currents in the distal part of apical dendrites is highly sensitive to the dynamic state of the dendritic membrane. Depending on the mode and frequency of activation these currents can exert a substantial influence on the input-output behavior of the pyramidal neurons.

A longitudinal study of serological patterns of respiratory infections in nine infected Danish swine herds

Sixteen litters of seven pigs from each of nine Danish farrow-to-finish herds were followed to investigate the serological patterns caused by natural infection with Mycoplasma hyopneumoniae, Pasteurella multocida toxin and Actinobacillus pleuropneumoniae serotypes 2, 5-7, 12. In seven of the herds, pigs were followed as two separate cohorts started 4 weeks apart, and in two herds only one cohort was followed.A total of 999 pigs were included in the study. The pigs were blood sampled at weaning and subsequently every fourth week until slaughter. All pigs were examined for antibodies against M. hyopneumoniae (enzyme-linked immunosorbent assay), P. multocida toxin (enzyme-linked immunosorbent assay) and A. pleuropneumoniae serotypes 2, 5-7, 12 (complement-fixation tests). The most-common pattern (28%) of seroconversion was that of pigs first seroconverting to A. pleuropneumoniae serotype 2, followed by seroconversion to M. hyopneumoniae. Each herd had a dominant serotype of A. pleuropneumoniae to which most pigs seroconverted. Seroconversion to the respiratory pathogens occurred mainly in the growing-to-finishing units (8-24 weeks). The risk of seroconversion to the P. multocida toxin was very low (<20%) and occurred late.None, four and seven herds tested seropositive to PRRS and to swine influenza virus subtypes H3N2 and H1N1, respectively, when testing 10 pigs per herd (selected randomly among the study pigs) at the age of 20 weeks.

Demonstration of airborne transmission of Actinobacillus pleuropneumoniae serotype 2 between simulated pig units located at close range

Airborne transmission of Actinobacillus pleuropneumoniae was studied as the percentage of air needed to establish airborne transmission from an infected pig unit into a neighbouring non-infected pig unit. The experiment was carried out in two containers constructed as pig units, placed 1m apart and connected by pipes. By manipulating the air pressure in the two units, the amount of ventilation air transferred from the infected pigs (unit A) to the non-infected pigs (unit B) was controlled and measured. In three experiments, between 48 and 50 specific pathogen free-pigs were randomly assigned to each of the two units. In unit A, five pigs (experiment 1) or eight pigs (experiments 2 and 3) were inoculated with A. pleuropneumoniae serotype 2. In experiments 1 and 3, 10% of the air was transferred from unit A to B; in experiment 2, 70% of the air was transferred. In the non-infected unit (B), 36% of the pigs seroconverted during experiment 2 (70% air transfer), whereas none of the pigs seroconverted in experiments 1 and 3 (10% air transfer). As air transmission between closely located pig units has been estimated to be less than 2% under field conditions, these results indicate that airborne transmission of A. pleuropneumoniae serotype 2 between closely located pig units is rare.

Postmortem analysis of three methoxyacetylfentanyl-related deaths in Denmark and in vitro metabolite profiling in pooled human hepatocytes

Methoxyacetylfentanyl belongs to the group of fentanyl analogues and has been associated with several deaths in recent years. We present three case reports of deceased individuals that tested positive for methoxyacetylfentanyl consumption, as well as in vitro and in vivo metabolite profiles. Methoxyacetylfentanyl was quantified by ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) in femoral blood, as well as in urine and brain tissue when these were available. Metabolite profiling was performed by incubating methoxyacetylfentanyl with pooled human hepatocytes (pHH) in Leibovitz's L-15 medium supplemented with fetal bovine serum. Metabolites were identified in vivo and in vitro using UHPLC-high resolution (HR)-MS/MS. The measured methoxyacetylfentanyl concentration was 0.022-0.056mg/kg (N=3) in femoral blood, 0.12mg/kg (N=1) in urine, and 0.074mg/kg (N=1) in brain tissue homogenate. A total of 10 metabolites were identified. The observed metabolic pathways were: hydroxylation(s), N-dealkylation, O-demethylation, deamination, glucuronidation, and combinations thereof. Major analytical targets in vitro and across measured biological samples in vivo were methoxyacetylfentanyl, the O-demethyl- metabolite, and the deamide-metabolite. Intoxication with methoxyacetylfentanyl was judged as the cause of death or a major contributing factor in all three presented cases.

A PET study of effects of chronic 3,4-methylenedioxymethamphetamine (MDMA, “ecstasy”) on serotonin markers in Göttingen minipig brain

The psychostimulant 3,4-methylendioxymethamphetamine (MDMA, "ecstasy") evokes degeneration of telencephalic serotonin innervations in rodents, nonhuman primates, and human recreational drug users. However, there has been no alternative to nonhuman primates for studies of the cognitive and neurochemical consequences of serotonin depletion in a large-bodied animal. Therefore, we used positron emission tomography (PET) with [(11)C]DASB to map the distribution of plasma membrane serotonin transporters in brain of Göttingen minipigs, first in a baseline condition, and again at 2 weeks after treatment with MDMA (i.m.), administered at a range of doses. In parallel PET studies, [(11)C]WAY-100635 was used to map the distribution of serotonin 5HT(1A) receptors. The acute MDMA treatment in awake pigs evoked 1 degrees C of hyperthermia. MDMA at total doses greater than 20 mg/kg administered over 2-4 days reduced the binding potential (pB) of [(11)C]DASB for serotonin transporters in porcine brain. A mean total dose of 42 mg/kg MDMA in four animals evoked a mean 32% decrease in [(11)C]DASB pB in mesencephalon and diencephalon, and a mean 53% decrease in telencephalic structures. However, this depletion of serotonin innervations was not associated with consistent alterations in the binding of [(11)C]WAY-100635 to serotonin 5HT(1A) receptors. Stereological cell counting of serotonin-positive neurons, which numbered 95,000 in the dorsal raphé nucleus of normal animals, was unaffected in MDMA-treated group. group.

Kinetic properties of a transient outward current in rat neocortical neurons

1. Whole-cell patch-clamp techniques were used to record outward currents in embryonic rat neocortical neurons maintained in culture. In the presence of tetrodotoxin and cadmium, depolarization evoked an outward current with a complex waveform. This outward current consisted of an initial fast transient component and a late, slowly inactivating component. 2. The two outward current components could be separated pharmacologically with the use of tetraethylammonium (TEA) and 4-aminopyridine (4-AP). TEA (20 mM) applied extracellularly completely blocked the late component, unmasking a fast transient outward current (TOC). 4-AP (5 mM) applied extracellularly blocked the early component while reducing the late component by 27.8 +/- 9.7% (mean +/- SE). 3. The TOC activated after a short delay and rose rapidly to a peak. The time to peak was voltage dependent and decreased with depolarization. In the presence of 200 microM extracellular cadmium, activation threshold was around -25 mV, and current amplitude increased with depolarization. The voltage-conductance relationship was well fitted by the use of the Boltzmann equation with a Vm of +19 mV for half activation and a slope factor of +6 mV. 4. On sustained depolarization the TOC rapidly inactivated and decayed to baseline within 500-600 ms. The decay phase followed a single exponential time course with a time constant of 55-65 ms. The decay time was most rapid at potentials from +5 to +20 mV and increased slightly with further depolarization. 5. Steady-state inactivation of the TOC, in the presence of cadmium, was complete near -10 mV and was totally relieved at potentials more negative than -75 mV. With the use of the Boltzmann equation, a Vm of -34 mV for half inactivation and a slope factor of -8.6 mV were found. 6. Recovery of the TOC from steady-state inactivation followed a single exponential time course and was voltage dependent. When the membrane potential was held at -84 mV during the conditioning pulse, the time constant of recovery was 17 ms, increasing to 45.2 and 58.1 ms at holding potentials of -64 and -44 mV, respectively. Holding at potentials more negative than -84 mV produced no further change in the recovery time course. 7. The presence of 200 microM external cadmium altered the TOC activation and inactivation curves. Removal of cadmium produced a -16-mV shift in the Vm for half activation and a -25-mV shift in the inactivation curve. This sensitivity to cadmium is higher than that reported in other systems.(ABSTRACT TRUNCATED AT 400 WORDS)

Analysis of the kinetics of synaptic inhibition points to a reduction in GABA release in area CA1 of the genetically epileptic mouse, El

In order to determine whether changes in synaptic inhibition are involved in chronic models of epilepsy, it is necessary to understand the factors which determine the kinetics of fast gamma-aminobutyric acid (GABA)ergic inhibition. For this purpose, we analyzed the decaying phase of isolated inhibitory postsynaptic currents (IPSC) in rats CA1 pyramidal cells. Reduction of GABA release (by reducing [Ca2+]o or paired-pulse stimulation) or blockade of GABA uptake (with tiagabine) led to the conclusion that small changes in the amount of GABA available for postsynaptic binding have little effect on the peak amplitude, but have marked effect on the duration of the IPSC. We then studied isolated GABAA receptor-mediated inhibition in area CA1 of the El mouse strain, which is genetically predisposed to epilepsy. Results were compared with the non-epileptogenic mother strain, ddY. Inhibitory postsynaptic potentials (IPSPs) in El mice (IPSPEl) were not significantly different in amplitude of those from ddY mice (IPSPddY). However, the rise-time and duration of IPSPEl were respectively about 25% and 50% shorter than those of IPSPddY. With appropriate pharmacological manipulation of GABA release or uptake, IPSPEl could be made to resemble the IPSPddY and vice versa. It is concluded that the synaptic release of GABA in area CA1 of the El mouse is decreased compared to that of the ddY mouse.

The role of excitatory amino acids in synaptic transmission in the hippocampus

We have highlighted some aspects of the action of excitatory amino acid transmission in the hippocampus. Fast epsps can be blocked by CNQX to reveal a component of synaptic transmission which is mediated by NMDA receptors. Extracellular recordings of ionic activities show that NMDA and non-NMDA ionophores are permeable to the major monovalent cations, while NMDA ionophores also appear to be permeable to Ca2+. Interactions of agonists applied by iontophoresis may be correlates of phenomena such as LTP, which can be evoked by appropriate synaptic stimulation.

Effect of tulathromycin on the carrier status of Actinobacillus pleuropneumoniae serotype 2 in the tonsils of pigs

The effect of a single or double dose of tulathromycin was evaluated in pigs carrying Actinobacillus pleuropneumoniae serotype 2 in their tonsils. Twenty-nine pigs from a reinfected specific pathogen-free-herd were selected from animals testing positive in an A pleuropneumoniae serotype 2-specific pcr test on tonsil scrapings and they were divided into three groups. The pigs in group 1 were treated subcutaneously with 2.5 mg/kg tulathromycin on day 0, the pigs in group 2 were treated with 2.5 mg/kg tulathromycin on days 0 and 4, and the pigs in group 3 were left untreated as controls. The pigs were tested by pcr on tonsil scrapings on days 0, 4, 11 and 33, and on day 33 all the animals were euthanased. There were no significant differences between the numbers of PCR-positive animals in the three groups on any of the sampling dates.

The effect of discontinued use of antimicrobial growth promoters on the risk of therapeutic antibiotic treatment in Danish farrow-to-finish pig farms

This study estimated the effect of discontinued use of antimicrobial growth promoters (duAGPs) on the risk of antibiotic treatment for diarrhoea, arthritis, pneumonia, unthriving and miscellaneous disorders in Danish pig farms. The estimation was done in a case-crossover study comparing: (1) the proportion of days per farm where treatment was performed (PDT) and (2) the proportion of pigs treated per day per farm at days where treatment was performed (PPT) before and after duAGPs at 68 farrow-to-finish farms. The farms were selected using a two-stage (veterinarian/farm) convenience sampling. On average, during the first year after duAGPs there was a significant increase in the risk of antibiotic treatment for diarrhoea (PDT: OR 2.5, 95% CI 1.7-3.8; PPT: OR 1.6, 95% CI 1.1-2.2). However, the effect varied among farms--some farms experienced substantial problems, while others experienced few problems after duAGPs. No effect was identified for the risk of treatment for other diseases.