Nanopatterning of oxide 2-dimensional electron systems using low-temperature ion milling.

We present a 'top-down' patterning technique based on ion milling performed at low-temperature, for the realization of oxide two-dimensional electron system devices with dimensions down to 160 nm. Using electrical transport and scanning Superconducting QUantum Interference Device measurements we demonstrate that the low-temperature ion milling process does not damage the 2DES properties nor creates oxygen vacancies-related conducting paths in the STO substrate. As opposed to other procedures used to realize oxide 2DES devices, the one we propose gives lateral access to the 2DES along the in-plane directions, finally opening the way to coupling with other materials, including superconductors.

HemaSpot, a Novel Blood Storage Device for HIV-1 Drug Resistance Testing.

HemaSpot, a novel dried-blood storage filter device, was used for HIV-1 pol resistance testing in 30 fresh United States blood samples and 54 previously frozen Kenyan blood samples. Genotyping succeeded in 79% and 58% of samples, respectively, improved with shorter storage and higher viral load, and had good (86%) resistance mutation concordance to plasma.

In vitro ictogenesis and parahippocampal networks in a rodent model of temporal lobe epilepsy.

Temporal lobe epilepsy (TLE) is a chronic epileptic disorder involving the hippocampal formation. Details on the interactions between the hippocampus proper and parahippocampal networks during ictogenesis remain, however, unclear. In addition, recent findings have shown that epileptic limbic networks maintained in vitro are paradoxically less responsive than non-epileptic control (NEC) tissue to application of the convulsant drug 4-aminopyridine (4AP). Field potential recordings allowed us to establish here the effects of 4AP in brain slices obtained from NEC and pilocarpine-treated epileptic rats; these slices included the hippocampus and parahippocampal areas such as entorhinal and perirhinal cortices and the amygdala. First, we found that both types of tissue generate epileptiform discharges with similar electrographic characteristics. Further investigation showed that generation of robust ictal-like discharges in the epileptic rat tissue is (i) favored by decreased hippocampal output (ii) reinforced by EC-subiculum interactions and (iii) predominantly driven by amygdala networks. We propose that a functional switch to alternative synaptic routes may promote network hyperexcitability in the epileptic limbic system.

Antiepileptic drugs and muscarinic receptor-dependent excitation in the rat subiculum.

Field and intracellular recordings were made in an in vitro slice preparation to establish whether the antiepileptic drugs topiramate and lamotrigine modulate cholinergic excitation in the rat subiculum. Bath application of carbachol (CCh, 70-100microM) induced: (i) spontaneous and synchronous field oscillations (duration=up to 7s) that were mirrored by intracellular depolarizations with rhythmic action potential bursts; and (ii) depolarizing plateau potentials (DPPs, duration=up to 2.5s) associated with action potential discharge in response to brief (50-100ms) intracellular depolarizing current pulses. Ionotropic glutamatergic receptor antagonists abolished the field oscillations without influencing DPPs, while atropine (1microM) markedly reduced both types of activity. Topiramate (10-100microM, n=8-13 slices) or lamotrigine (50-400microM, n=3-12) decreased in a dose-dependent manner, and eventually abolished, CCh-induced field oscillations. During topiramate application, these effects were accompanied by marked DPP reduction. When these antiepileptic drugs were tested on DPPs recorded in the presence of CCh+ionotropic glutamatergic and GABA receptor antagonists, only topiramate reduced DPPs (n=5-19/dose; IC(50)=18microM, n=48). Similar effects were induced by topiramate during metabotropic glutamate receptor antagonism (n=5), which did not influence DPPs. Thus, topiramate and lamotrigine reduce CCh-induced epileptiform synchronization in the rat subiculum but only topiramate is effective in controlling DPPs. We propose that muscarinic receptor-mediated excitation represents a target for the action of some antiepileptic drugs such as topiramate.

Reduced GABAB receptor subunit expression and paired-pulse depression in a genetic model of absence seizures.

Neocortical networks play a major role in the genesis of generalized spike-and-wave (SW) discharges associated with absence seizures in humans and in animal models, including genetically predisposed WAG/Rij rats. Here, we tested the hypothesis that alterations in GABA(B) receptors contribute to neocortical hyperexcitability in these animals. By using Real-Time PCR we found that mRNA levels for most GABA(B(1)) subunits are diminished in epileptic WAG/Rij neocortex as compared with age-matched non-epileptic controls (NEC), whereas GABA(B(2)) mRNA is unchanged. Next, we investigated the cellular distribution of GABA(B(1)) and GABA(B(2)) subunits by confocal microscopy and discovered that GABA(B(1)) subunits fail to localize in the distal dendrites of WAG/Rij neocortical pyramidal cells. Intracellular recordings from neocortical cells in an in vitro slice preparation demonstrated reduced paired-pulse depression of pharmacologically isolated excitatory and inhibitory responses in epileptic WAG/Rij rats as compared with NECs; moreover, paired-pulse depression in NEC slices was diminished by a GABA(B) receptor antagonist to a greater extent than in WAG/Rij rats further suggesting GABA(B) receptor dysfunction. In conclusion, our data identify changes in GABA(B) receptor subunit expression and distribution along with decreased paired-pulse depression in epileptic WAG/Rij rat neocortex. We propose that these alterations may contribute to neocortical hyperexcitability and thus to SW generation in absence epilepsy.

Effects of gap junction blockers on human neocortical synchronization.

Field potentials and intracellular recordings were obtained from human neocortical slices to study the role of gap junctions (GJ) in neuronal network synchronization. First, we examined the effects of GJ blockers (i.e., carbenoxolone, octanol, quinine, and quinidine) on the spontaneous synchronous events (duration = 0.2-1.1 s; intervals of occurrence = 3-27 s) generated by neocortical slices obtained from temporal lobe epileptic patients during application of 4-aminopyridine (4AP, 50 muM) and glutamatergic receptor antagonists. The synchronicity of these potentials (recorded at distances up to 5 mm) was decreased by GJ blockers within 20 min of application, while prolonged GJ blockers treatment at higher doses made them disappear with different time courses. Second, we found that slices from patients with focal cortical dysplasia (FCD) could generate in normal medium spontaneous synchronous discharges (duration = 0.4-8 s; intervals of occurrence = 0.5-90 s) that were (i) abolished by NMDA receptor antagonists and (ii) slowed down by carbenoxolone. Finally, octanol or carbenoxolone blocked 4AP-induced ictal-like discharges (duration = up to 35 s) in FCD slices. These data indicate that GJ play a role in synchronizing human neocortical networks and may implement epileptiform activity in FCD.

Synaptic hyperexcitability of deep layer neocortical cells in a genetic model of absence seizures.

We used sharp-electrode, intracellular recordings in an in vitro brain slice preparation to study the excitability of neocortical neurons located in the deep layers (>900 microm from the pia) of epileptic (180-210-days old) Wistar Albino Glaxo/Rijswijk (WAG/Rij) and age-matched, non-epileptic control (NEC) rats. Wistar Albino Glaxo/Rijswijk rats represent a genetic model of absence seizures associated with generalized spike and wave (SW) discharges in vivo. When filled with neurobiotin, these neurons had a typical pyramidal shape with extensive apical and basal dendritic trees; moreover, WAG/Rij and NEC cells had similar fundamental electrophysiological and repetitive firing properties. Sequences of excitatory postsynaptic potentials (EPSPs) and hyperpolarizing inhibitory postsynaptic potentials (IPSPs) were induced in both the strains by electrical stimuli delivered to the underlying white matter or within the neocortex; however, in 24 of 55 regularly firing WAG/Rij cells but only in 2 of 25 NEC neurons, we identified a late EPSP that (1) led to action potential discharge and (2) was abolished by the N-methyl-D-aspartate (NMDA) receptor antagonist 3,3-(2-carboxypiperazine-4-yl)-propyl-1-phosphonate (20 microM; n = 8/8 WAG/Rij cells). Finally, we found that the fast and slow components of the stimulus-induced IPSPs recorded during the application of glutamatergic receptor antagonists had similar reversal potentials in the two strains, while the peak conductance of the fast IPSP was significantly reduced in WAG/Rij cells. These findings document an increase in synaptic excitability that is mediated by NMDA receptors, in epileptic WAG/Rij rat neurons located in neocortical deep layers. We propose that this mechanism may be instrumental for initiating and maintaining generalized SW discharges in vivo.

GABAA receptor-dependent synchronization leads to ictogenesis in the human dysplastic cortex.

Patients with Taylor's type focal cortical dysplasia (FCD) present with seizures that are often medically intractable. Here, we attempted to identify the cellular and pharmacological mechanisms responsible for this epileptogenic state by using field potential and K+-selective recordings in neocortical slices obtained from epileptic patients with FCD and, for purposes of comparison, with mesial temporal lobe epilepsy (MTLE), an epileptic disorder that, at least in the neocortex, is not characterized by any obvious structural aberration of neuronal networks. Spontaneous epileptiform activity was induced in vitro by applying 4-aminopyridine (4AP)-containing medium. Under these conditions, we could identify in FCD slices a close temporal relationship between ictal activity onset and the occurrence of slow interictal-like events that were mainly contributed by GABAA receptor activation. We also found that in FCD slices, pharmacological procedures capable of decreasing or increasing GABAA receptor function abolished or potentiated ictal discharges, respectively. In addition, the initiation of ictal events in FCD tissue coincided with the occurrence of GABAA receptor-dependent interictal events leading to [K+]o elevations that were larger than those seen during the interictal period. Finally, by testing the effects induced by baclofen on epileptiform events generated by FCD and MTLE slices, we discovered that the function of GABAB receptors (presumably located at presynaptic inhibitory terminals) was markedly decreased in FCD tissue. Thus, epileptiform synchronization leading to in vitro ictal activity in the human FCD tissue is initiated by a synchronizing mechanism that paradoxically relies on GABAA receptor activation causing sizeable increases in [K+]o. This mechanism may be facilitated by the decreased ability of GABAB receptors to control GABA release from interneuron terminals.

Initiation of electrographic seizures by neuronal networks in entorhinal and perirhinal cortices in vitro.

The hippocampus is often considered to play a major role in the pathophysiology of mesial temporal lobe epilepsy. However, emerging clinical and experimental evidence suggests that parahippocampal areas may contribute to a greater extent to limbic seizure initiation, and perhaps epileptogenesis. To date, little is known about the participation of entorhinal and perirhinal networks to epileptiform synchronization. Here, we addressed this issue by using simultaneous field potential recordings in horizontal rat brain slices containing interconnected limbic structures that included the hippocampus proper. Epileptiform discharges were disclosed by bath applying the convulsant drug 4-aminopyridine (50 microM) or by superfusing Mg(2+)-free medium. In the presence of 4-aminopyridine, slow interictal- (duration=2.34+/-0.29 s; interval of occurrence=25.75+/-2.11 s, n=16) and ictal-like (duration=31.25+/-3.34 s; interval of occurrence=196.96+/-21.56 s, n=17) discharges were recorded in entorhinal and perirhinal cortices after abating the propagation of CA3-driven interictal activity to these areas following extended hippocampal knife cuts. Simultaneous recordings obtained from the medial and lateral entorhinal cortex, and from the perirhinal cortex revealed that interictal and ictal discharges could initiate from any of these areas and propagate to the neighboring structure with delays of 8-66 ms. However, slow interictal- and ictal-like events more often originated in the medial entorhinal cortex and perirhinal cortex, respectively. Cutting the connections between entorhinal and perirhinal cortices (n=10), or functional inactivation of cortical areas by local application of a glutamatergic receptor antagonist (n=11) made independent epileptiform activity occur in all areas. These procedures also shortened ictal discharge duration in the entorhinal cortices, but not in the perirhinal area. Similar results could be obtained by applying Mg(2+)-free medium (n=7). These findings indicate that parahippocampal networks provide independent epileptiform synchronization sufficient to sustain limbic seizures as well as that the perirhinal cortex plays a preferential role in in vitro ictogenesis.

Involvement of amygdala networks in epileptiform synchronization in vitro.

We used field potential and intracellular recordings in rat brain slices that included the hippocampus, a portion of the basolateral/lateral nuclei of the amygdala (BLA) and the entorhinal cortex (EC). Bath application of the convulsant 4-aminopyridine (50 microM) to slices (n=12) with reciprocally connected areas, induced short-lasting interictal-like epileptiform discharges that (i) occurred at intervals of 1.2-2.8 s, (ii) originated in CA3, and (iii) spread to EC and BLA. Cutting the Schaffer collaterals abolished them in both parahippocampal areas where slower interictal-like (interval of occurrence=4-17 s) and prolonged ictal-like discharges (duration=15+/-6.9 s, mean+/-S.D., n=7) appeared. These new types of epileptiform activity originated in either EC or BLA. Similar findings were obtained in slices (n=19) in which the hippocampus outputs were not connected with the EC and BLA under control conditions. Cutting the EC-BLA connections made independent slow interictal- and ictal-like activities appear in both areas (n=5). NMDA receptor antagonism (n=6) abolished ictal-like discharges and reduced the duration of the slow interictal-like events. Repetitive stimulation of BLA at 0.5-1 Hz in Schaffer collateral cut slices, induced interictal-like epileptiform depolarizations in EC and reversibly blocked ictal-like activity (n=14). Thus, CA3 outputs in intact slices entrain EC and BLA networks into an interictal-like pattern that inhibits the propensity of these parahippocampal areas to generate prolonged ictal-like paroxysms. Accordingly, NMDA receptor-dependent ictal-like events are initiated in BLA or EC once the propagation of CA3-driven interictal-like discharges to these areas is abated by cutting the Schaffer collaterals. Similar inhibitory effects also occur by activating BLA outputs directed to EC at rates that mimic the CA3-driven interictal-like pattern.

Involvement of cholinergic and gabaergic systems in the fragile X knockout mice.

Fragile X syndrome is an inherited cause of mental retardation. We used extra- and intracellular recordings in brain slices obtained from wild type and fragile X knockout mice to establish whether bath application of the cholinergic agent carbachol (5 microM) induces different responses in neurons of the subiculum, a limbic structure involved in learning and memory. We found that carbachol diminished excitatory post-synaptic responses induced by CA1 stratum radiatum stimulation in wild type mice, but caused an unexpected increase in knockout animals. Moreover, these responses augmented in knockout mice after carbachol washout, a phenomenon that resembled the muscarinic long-term potentiation seen in wild type mice during application of carbachol and GABA(A) receptor antagonists. We also used paired-pulse stimulation to determine whether the changes in synaptic excitability induced by carbachol were caused by pre- or post-synaptic mechanism. Under control conditions, this protocol induced facilitation in both wild type and knockout mice; in contrast, during carbachol application, this facilitatory effect was seen in wild type mice only. In conclusion, our data highlight for the first time differences in cholinergic and GABA-ergic mechanisms that may contribute to the phenotype of fragile X patients.

Network and intrinsic contributions to carbachol-induced oscillations in the rat subiculum.

Low-frequency network oscillations occur in several areas of the limbic system where they contribute to synaptic plasticity and mnemonic functions that are in turn modulated by cholinergic mechanisms. Here we used slices of the rat subiculum (a limbic area involved in cognitive functions) to establish how network and single neuron (intrinsic) membrane mechanisms participate to the rhythmic oscillations elicited by the cholinergic agent carbachol (CCh, 50-100 microM). We have found that CCh-induced network oscillations (intraoscillatory frequency = 5-16 Hz) are abolished by an antagonist of non-N-methyl-D-aspartate (NMDA) glutamatergic receptors (n = 6 slices) but persist during blockade of GABA receptors (n = 16). In addition, during application of glutamate and GABA receptor antagonists, single subicular cells generate burst oscillations at 2.1-6.8 Hz when depolarized with steady current injection. These intrinsic burst oscillations disappear during application of a Ca(2+) channel blocker (n = 6 cells), intracellular Ca(2+) chelation (n = 6), or replacement of extracellular Na(+) (n = 4) but persist in recordings made with electrodes containing a blocker of voltage-gated Na(+) channels (n = 7). These procedures cause similar effects on CCh-induced depolarizing plateau potentials that are contributed by a Ca(2+)-activated nonselective cationic conductance (I(CAN)). Network and intrinsic oscillations along with depolarizing plateau potentials were abolished by the muscarinic receptor antagonist atropine. In conclusion, our findings demonstrate that low-frequency oscillations in the rat subiculum rely on the muscarinic receptor-dependent activation of an intrinsic oscillatory mechanism that is presumably contributed by I(CAN) and are integrated within the network via non-NMDA receptor-mediated transmission.

Electrophysiology of regular firing cells in the rat perirhinal cortex.

The electrophysiological properties of neurons in the rat perirhinal cortex were analyzed with intracellular recordings in an in vitro slice preparation. Cells included in this study (n = 59) had resting membrane potential (RMP) = -73.9 +/- 8.5 mV (mean +/- SD), action potential amplitude = 95.5 +/- 10.4 mV, input resistance = 36.1 +/- v 15.7 M omega, and time constant = 13.9 +/- 3.4 ms. When filled with neurobiotin (n = 27) they displayed a pyramidal shape with an apical dendrite and extensive basal dendritic tree. Injection of intracellular current pulses revealed: 1) a tetrodotoxin (TTX, 1 microM)-sensitive, inward rectification in the depolarizing direction (n = 6), and 2) a time- and voltage-dependent hyperpolarizing sag that was blocked by extracellular Cs+ (3 mM, n = 5) application. Prolonged (up to 3 s) depolarizing pulses made perirhinal cells discharge regular firing of fast action potentials that diminished over time in frequency and reached a steady level (i.e., adapted). Repetitive firing was followed by an afterhyperpolarization that was decreased, along with firing adaptation, by the Ca(2+)-channel blocker Co2+ (2 mM, n = 6). Action potential broadening became evident during repetitive firing. This behavior, which was more pronounced when larger pulses of depolarizing current were injected (and thus when repetitive firing attained higher rates), was markedly decreased by Co2+ application. Subthreshold membrane oscillations at 5-12 Hz became apparent when cells were depolarized by 10-20 mV from RMP, and action potential clusters appeared with further depolarization. Application of glutamatergic and GABAA receptor antagonists (n = 4), CO2+ (n = 6), or Cs+ (n = 5) did not prevent the occurrence of these oscillations that were abolished by TTX (n = 6). Our results show that pyramidal-like neurons in the perirhinal cortex are regular firing cells with electrophysiological features resembling those of other cortical pyramidal elements. The ability to generate subthreshold membrane oscillations may play a role in synaptic plasticity and thus in the mnemonic processes typical of this limbic structure.

Spindle-like thalamocortical synchronization in a rat brain slice preparation.

We obtained rat brain slices (550-650 microm) that contained part of the frontoparietal cortex along with a portion of the thalamic ventrobasal complex (VB) and of the reticular nucleus (RTN). Maintained reciprocal thalamocortical connectivity was demonstrated by VB stimulation, which elicited orthodromic and antidromic responses in the cortex, along with re-entry of thalamocortical firing originating in VB neurons excited by cortical output activity. In addition, orthodromic responses were recorded in VB and RTN following stimuli delivered in the cortex. Spontaneous and stimulus-induced coherent rhythmic oscillations (duration = 0.4-3.5 s; frequency = 9-16 Hz) occurred in cortex, VB, and RTN during application of medium containing low concentrations of the K(+) channel blocker 4-aminopyridine (0.5-1 microM). This activity, which resembled electroencephalograph (EEG) spindles recorded in vivo, disappeared in both cortex and thalamus during application of the excitatory amino acid receptor antagonist kynurenic acid in VB (n = 6). By contrast, cortical application of kynurenic acid (n = 4) abolished spindle-like oscillations at this site, but not those recorded in VB, where their frequency was higher than under control conditions. Our findings demonstrate the preservation of reciprocally interconnected cortical and thalamic neuron networks that generate thalamocortical spindle-like oscillations in an in vitro rat brain slice. As shown in intact animals, these oscillations originate in the thalamus where they are presumably caused by interactions between RTN and VB neurons. We propose that this preparation may help to analyze thalamocortical synchronization and to understand the physiopathogenesis of absence attacks.

The inhibitory effects of interleukin-6 on synaptic plasticity in the rat hippocampus are associated with an inhibition of mitogen-activated protein kinase ERK.

Several cytokines have short-term effects on synaptic transmission and plasticity that are thought to be mediated by the activation of intracellular protein kinases. We have studied the effects of interleukin-6 (IL-6) on the expression of paired pulse facilitation (PPF), posttetanic potentiation (PTP), and long-term potentiation (LTP) in the CA1 region of the hippocampus as well as on the activation of the signal transducer and activator of transcription-3 (STAT3), the mitogen-activated protein kinase ERK (MAPK/ERK), and the stress-activated protein kinase/c-Jun NH(2)-terminal kinase (SAPK/JNK). IL-6 induced a marked and dose-dependent decrease in the expression of PTP and LTP that could be counteracted by the simultaneous treatment with the tyrosine kinase inhibitor lavendustin A (LavA) but did not significantly affect PPF. The IL-6-induced inhibition of PTP and LTP was accompanied by a simulation of STAT3 tyrosine phosphorylation and an inhibition of MAPK/ERK dual phosphorylation, in the absence of changes in the state of activation of SAPK/JNK. Both effects of IL-6 on STAT3 and MAPK/ERK activation were effectively counteracted by LavA treatment. The results indicate the tyrosine kinases and MAPK/ERK are involved in hippocampal synaptic plasticity and may represent preferential intracellular targets for the actions of IL-6 in the adult nervous system.

Interleukin-6 inhibits neurotransmitter release and the spread of excitation in the rat cerebral cortex.

Cytokines are extracellular mediators that have been reported to affect neurotransmitter release and synaptic plasticity phenomena when applied in vitro. Most of these effects occur rapidly after the application of the cytokines and are presumably mediated through the activation of protein phosphorylation processes. While many cytokines have an inflammatory action, interleukin-6 (IL-6) has been found to have a neuroprotective effect against ischaemia lesions and glutamate excitotoxicity, and to increase neuronal survival in a variety of experimental conditions. In this paper, the functional effects of IL-6 on the spread of excitation visualized by dark-field/infrared videomicroscopy in rat cortical slices and on glutamate release from cortical synaptosomes were analysed and correlated with the activation of the STAT3, mitogen-activated protein kinase ERK (MAPK/ERK) and stress-activated protein kinase/cJun NH2-terminal kinase (SAPK/JNK) pathways. We have found that IL-6 depresses the spread of excitation and evoked glutamate release in the cerebral cortex, and that these effects are accompanied by a stimulation of STAT3 tyrosine phosphorylation, an inhibition of MAPK/ERK activity, a decreased phosphorylation of the presynaptic MAPK/ERK substrate synapsin I and no detectable effects on SAPK/JNK. The effects of IL-6 were effectively counteracted by treatment of the cortical slices with the tyrosine kinase inhibitor lavendustin A. The inhibitory effects of IL-6 on glutamate release and on the spread of excitation in the rat cerebral cortex indicate that the protective effect of IL-6 on neuronal survival could be mediated by a downregulation of neuronal activity, release of excitatory neurotransmitters and MAPK/ERK activity.

Assessment of endothelial cell proliferation in primary breast carcinoma and its association with axillary lymph node status.

The correlation between angiogenesis as assessed by endothelial cell proliferation in blood/lymphatic vessels in primary breast carcinomas, and axillary lymph-node metastasis was studied using a case-control design. Primary breast carcinomas, < 2 cm in diameter, from 26 axillary node positive patients (case), were compared with neoplasms from 45 node-negative patients (control). Vascularity, as assessed by vessel density, and endothelial cell proliferation were measured in a single tissue section using a double immunohistochemical staining technique using MIBI (Ki-67) and FVIII antibodies. No association between vascularity and node status was found (P > 0.70). Node positive breast carcinomas had, on average, significantly smaller proliferating vessels (140+/-7 microm in perimeter) in the primary lesion when compared with node negative tumours (164+/-7 microm in perimeter (P < 0.02). In addition, the frequency of relatively small vessels (less than 180 microm in perimeter) with proliferating endothelium was higher in node positive carcinomas than lymph-node negative neoplasms (P < 0.03). This association between node status and the size and frequency of blood/lymphatic vessels with proliferating endothelium in primary carcinoma may have important implications in metastasis.

Androgen receptor expression of proliferating basal and luminal cells in adult murine ventral prostate.

Maintenance of the size and differentiated function of the adult prostate is dependent on testicular androgens. In this study, simultaneous androgen receptor (AR) immunohistochemistry and [(3)H]thymidine labelling was used to characterise the proliferating epithelial cells of the murine ventral prostate. Proliferation in the adult prostate was more prevalent in the basal cell population with 1.8&percent; AR-negative cells labelled with [(3)H]thymidine as compared with 0.7% AR-expressing luminal cells. Three weeks following castration of mice, the atrophied prostate contained rudimentary glands composed of both luminal and basal cells with the proportion of AR-expressing basal cells reduced from 50 to 25%. Administration of testosterone enanthate to castrated mice induced a recapitulation of the prostate gland that was preceded by up-regulation of AR expression in basal cells to normal adult levels (50% AR-positive cells) by 12 h following testosterone injection. Proliferation of AR-positive luminal cells peaked at 48 h (22.8%) while proliferation of AR-negative basal cells peaked at 96 h (6.1%) following testosterone administration. These results suggest that distinct populations of luminal and basal cells are resistant to castration-induced involution of the prostate but remain responsive to direct or indirect testosterone effects and recapitulate the gland following administration of testosterone.

Asymptomatic carotid artery stenosis associated with peripheral vascular disease: a prospective study.

This study aimed to determine the prevalence of symptomless internal carotid artery stenosis in consecutive patients presenting with peripheral vascular disease. Duplex ultrasound screening of the carotid arteries was used to determine the degree of stenosis. Co-morbidities were recorded together with age, sex and tobacco use. Internal carotid artery stenosis of > 50% was found in 35% of patients. Among these there was > or = 70% stenosis in 18% of patients and of this group 5% had an occluded carotid vessel at first presentation. Males presented with peripheral vascular disease and associated carotid stenoses at a younger age than females. Male smokers had a higher prevalence of stenosis (P = 0.036) but all smokers had developed stenoses 3-5 years before non-smokers. Females with abdominal aortic aneurysms had a greater prevalence of carotid stenosis (P = 0.037), and male aneurysmal disease diminished stenosis prevalence (P = 0.023). Men with an elevated serum creatinine were more likely to have a stenosis (P = 0.019), but not women. The other co-morbidities were not specifically associated with carotid artery stenosis.

Modulation of epileptiform activity by adenosine A1 receptor-mediated mechanisms in the juvenile rat hippocampus.

The modulatory role played by purinergic mechanisms on the epileptiform discharges induced by 4-aminopyridine (4AP, 50 microM) in juvenile (10 to 25-day-old) rat hippocampal slices was studied with field potential recordings in the CA3 stratum radiatum. 4AP-induced activity consisted of interictal and ictal discharges along with isolated gamma-aminobutyric acid-mediated potentials. The adenosine analogues 2-Cl-adenosine (10-200 microM) and N-ethylcarboxamido-adenosine (5-10 microM), the A1 receptor agonist N6-(L2-phenylisopropyl)-adenosine (2-10 microM), and the adenosine uptake inhibitor dipyridamole (1-40 microM) reduced and eventually abolished interictal and ictal discharges with IC50 values that were larger for ictal discharges as compared to interictal activity. These purinergic agents did not modify the rate of occurrence of the gamma-aminobutyric acidmediated potentials recorded during application of excitatory amino acid receptor antagonists. The changes induced by 2-Cl-adenosine, N6-(L2-phenylisopropyl)-adenosine, or dypiridamole were reversed by caffeine (500 microM) or 8-cyclopentyl-1,3-dipropylxantine (100 microM). However, these adenosine receptor antagonists did not alter the epileptiform discharges induced by 4AP. The depressant effects induced by N6-(L2-phenylisopropyl)-adenosine on the epileptiform activity were maintained in the presence of barium (2 mM), which blocks adenosine postsynaptic actions. These results demonstrate that activation of adenosine A1 receptors in the juvenile rat hippocampus leads to an anticonvulsant action that can be ascribed to a decreased release of glutamate from CA3 pyramidal cell terminals. We also propose that during the first weeks of postnatal life endogenous adenosine does not activate A1 receptors to a degree to control the ability of hippocampal neurons to generate epileptiform activity in the 4AP model.