Toxicity and bacterial anti-motility activities of the hydroethanolic extract of Acacia senegal (L.) Willd (Fabaceae) leaves.

BACKGROUND: Acacia senegal is a plant traditionally used for its various properties, including the treatment of infectious diseases. Recently, our team has demonstrated the ability of the hydroethanolic extract of the leaves to increase the activity of phenicol antibiotics against multi-resistant bacteria. The aim of this work is to determine the toxicological effects of the extract and its capacity to inhibit the bacterial mobility of Gram-negative bacteria, in order to evaluate the level of safety use of this plant. METHODS: The cytotoxicity test was performed using the neutral red absorption method. Acute and sub-acute oral toxicity were conducted on NMRI mice and Wistar rats. The behaviour and adverse effects were recorded during the 14 days of the acute study. For the subacute test, biochemical parameters, food and water consumption, and morphological parameters were determined. The anti-motility activities were evaluated on Pseudomonas aeruginosa PA01 and Escherichia coli AG100, using specific concentrations of Agar as required by the method. RESULTS: HEASG induced inhibition of keratinocytes cell growth with an IC50 of 1302 ± 60 µg/mL. For the acute toxicity study in mice, the single dose of extract of 2000 mg/kg body weight caused no deaths and no behavioural changes were observed; therefore, the median lethal dose (LD50) of HEASG was calculated to 5000 mg/kg body weight. In Wistar rats, no mortality was observed at 250, 500 and 1000 mg/kg/day during the 28-day subacute oral toxicity study. The weights of both females and males increased globally over time, regardless of the batch. No statistically significant differences were registered for organ weights and biochemical parameters, except for chloride for biochemical parameters. Water and food consumption did not change significantly. Furthermore, no macroscopic changes in organ appearance were observed. Regarding anti-motility activity, the extract has reduced the swarming motility of PA01 and AG100 significantly at the concentration of 32 µg/mL (P < 0.001). The extract has reduced the swimming motility (P < 0.01) of PA01 but not AG100. CONCLUSIONS: The results suggest that hydroethanolic extract of A. senegal leaves has significant activity against bacterial motility and relatively low toxicity.

Enhanced photoemission from laser-excited plasmonic nano-objects in periodic arrays.

The process of photoelectron emission from gold surfaces covered with nano-objects that are organized in the form of a periodic array is addressed in the short laser pulse regime ([Formula: see text] fs) at moderate intensities [Formula: see text] W cm(-2) and for various laser wavelengths. The emission spectrum from a gold single crystal measured under the same conditions is used for reference. The comparison of the photo-emission yield and the energy of the ejected electrons with their counterparts from the (more simple) reference system shows that the periodic conditions imposed on the target surface drastically enhance both quantities. In addition to the standard mechanism of Coulomb explosion, a second mechanism comes into play, driven by surface plasmon excitation. This can be clearly demonstrated by varying the laser wavelength. This interpretation of the experimental data is supported by predictions from model calculations that account both for the primary quantum electron emission and for the subsequent surface-plasmon-driven acceleration in the vacuum. Despite the fact that the incident laser intensity is as low as [Formula: see text] W cm(-2), such a structured target permits generating electrons with energies as high as 300 eV. Experiments with two incident laser beams of different wavelengths with an adjustable delay, have also been carried out. The results show that there exist various channels for the decay of the photo-emission signal, depending on the target type. These observations are shedding light on the various relaxation mechanisms that take place on different timescales.

Multi-channel electronic and vibrational dynamics in polyatomic resonant high-order harmonic generation.

High-order harmonic generation in polyatomic molecules generally involves multiple channels of ionization. Their relative contribution can be strongly influenced by the presence of resonances, whose assignment remains a major challenge for high-harmonic spectroscopy. Here we present a multi-modal approach for the investigation of unaligned polyatomic molecules, using SF6 as an example. We combine methods from extreme-ultraviolet spectroscopy, above-threshold ionization and attosecond metrology. Fragment-resolved above-threshold ionization measurements reveal that strong-field ionization opens at least three channels. A shape resonance in one of them is found to dominate the signal in the 20-26 eV range. This resonance induces a phase jump in the harmonic emission, a switch in the polarization state and different dynamical responses to molecular vibrations. This study demonstrates a method for extending high-harmonic spectroscopy to polyatomic molecules, where complex attosecond dynamics are expected.

Spasmolytic effects of aqueous extract of mixture from Aframomumum melegueta (K Schum) - Citrus aurantifolia (Christm and Panzer) on isolated trachea from rat.

The spasmolytic properties of the aqueous extract of Aframomum melegueta (K Schum) and Citrus aurantifolia (Christm and Panzer) (AMCA) mixture were tested on isolated rat trachea. Inhibition of the contraction was observed the in presence of the AMCA (EC 50 = 1.80 ± 0.48 mg/mL) after a pre contraction of the trachea by acetylcholine (10⁻5 M). With propranolol (10⁻6 M), the spasmolytic activity of the mixture was inhibited and the concentration-response curve shifted to the right. The EC50 value was then 2.60 ± 0.41 mg/mL. AMCA also inhibited contraction induced by KCl (4.10⁻² M) with EC50 value = 1.86 ± 0.65 mg/mL. These results clearly show the relaxing effect of the aqueous extract on the isolated rat trachea. This effect involved some ß-adrenergic receptor inhibition.

Adjunctive therapy with oxcarbazepine in children with partial seizures. The Oxcarbazepine Pediatric Study Group.

OBJECTIVE: To evaluate the safety and efficacy of oxcarbazepine (OXC) as adjunctive therapy in children with inadequately controlled partial seizures on one or two concomitant antiepileptic drugs (AEDs). BACKGROUND: OXC has shown antiepileptic activity in several comparative monotherapy trials in newly diagnosed patients with epilepsy, and in a placebo-controlled monotherapy trial in hospitalized patients evaluated for epilepsy surgery. DESIGN: A total of 267 patients were evaluated in a multicenter, randomized, placebo-controlled trial consisting of three phases: 1) a 56-day baseline phase (patients maintained on their current AEDs); 2) a 112-day double-blind treatment phase (patients received either OXC 30-46 mg/kg/day orally or placebo); and 3) an open-label extension phase. Data are reported only from the double-blind treatment phase; the open-label extension phase is ongoing. METHODS: Children (3 to 17 years old) with inadequately controlled partial seizures (simple, complex, and partial seizures evolving to secondarily generalized seizures) were enrolled. RESULTS: Patients treated with OXC experienced a significantly greater median percent reduction from baseline in partial seizure frequency than patients treated with placebo (p = 0.0001; 35% versus 9%, respectively). Forty-one percent of patients treated with OXC experienced a > or =50% reduction from baseline in partial seizure frequency per 28 days compared with 22% of patients treated with placebo (p = 0.0005). Ninety-one percent of the group treated with OXC and 82% of the group treated with placebo reported > or =1 adverse event; vomiting, somnolence, dizziness, and nausea occurred more frequently (twofold or greater) in the group treated with OXC. CONCLUSION: OXC adjunctive therapy administered in a dose range of 6 to 51 mg/kg/day (median 31.4 mg/kg/day) is safe, effective, and well tolerated in children with partial seizures.

Stimulus-response incompatibility effects on event-related potentials in children with attention-deficit hyperactivity disorder.

In order to test the hypothesis of a response choice deficit in attention-deficit hyperactivity disorder (ADHD) children, event-related potentials (ERPs) were recorded from 30 scalp electrodes in 21 ADHD and 21 normal boys during a spatial stimulus-response compatibility (SRC) task. ADHD children made fewer correct responses than control children, but did not show a larger incompatibility effect on response speed and accuracy. In ERPs, ADHD children had longer N1 latency and larger condition effect on the frontal N2, which would reflect a greater frontal involvement for the correct responses. The ADHD group who performed the SRC task first showed a larger condition effect on an early occipital P3 only, while the ADHD group who performed the SRC task second showed a larger condition effect on a later central P650 component and on a late parietal NSW, as compared with normal controls. These results suggest strategic differences in information processing in ADHD children, rather than a specific deficit.

ERPs and behavioral inhibition in a Go/No-go task in children with attention-deficit hyperactivity disorder.

In order to study the behavioral responses and the brain inhibition process in children with attention-deficit hyperactivity disorder (ADHD), Event-Related Potentials (ERPs) were recorded from 30 scalp electrodes in 21 ADHD and 21 normal boys during performing a Go/No-go task. ADHD children made fewer correct responses to both Go and No-go stimuli than normal controls. The frontal N2 amplitude was larger for No-go stimuli than Go stimuli in both groups, reflecting inhibition of responding. Smaller N2 amplitudes to No-go stimuli were found in ADHD children, but only when the Go/No-go task was performed after a first stimulus-response compatibility (SRC) task. In addition, the controls exhibited a prolonged N2 only when the Go/No-go task was performed second. However, the ADHD subjects exhibited this prolonged N2 when the task was first, but not when it was second. These results suggest an inhibitory regulation problem rather an inhibition deficit in ADHD children.

ERP differences in visual attention processing between attention-deficit hyperactivity disorder and control boys in the absence of performance differences.

Event-related potentials (ERPs) were recorded during a visual two-choice reaction time (RT) task in attention-deficit hyperactivity disorder (ADHD) and control boys selected using strict inclusion and exclusion criteria. No group differences were found in mean RT and correct responses. Although early occipital ERPs were not affected in the ADHD group, the peak latency of early anterior ERPs (N1, P1, N2) was significantly delayed. ADHD showed a larger effect of stimulus type on the frontal negativity (N530) and the posterior late negativity (nSW) and a smaller effect of stimulus type on anterior N2 and posterior P3b amplitude. The development of N530 and P450 amplitude across blocks of five trials was analyzed using orthogonal polynomial trend analysis of variance software. In the control group, P450 amplitude to "frequent" stimuli reduced across blocks. In the ADHD group, N530 amplitude increased for "rare" stimuli across blocks. It is suggested that the ADHD group showed a lack of automatization of the categorization process with increasing time on task for which they compensated by controlled attentional processes.

Stroke-like episodes in autosomal recessive cytochrome oxidase deficiency.

Stroke-like episodes, defined as periods of acute localized neurological dysfunction during which brain imagery suggests cerebral ischemia but vascular anatomy is normal, occurred in 3 patients with autosomal recessive Saguenay-Lac St-Jean (SLSJ) cytochrome oxidase (COX) deficiency. The patients developed focal neurological deterioration and frontal hypodensities on cerebral computerized tomography (CT). Arteriography, performed in 1 patient during an acute episode, showed normal vascular anatomy. Nevertheless, capillary shunting was evident both in regions that appeared abnormal on the initial cerebral CT study and in regions that appeared normal but subsequently developed Leigh disease. Stroke-like episodes did not exacerbate systemic acidosis, and acidotic decompensations occurred independently of stroke-like episodes. In conclusion, stroke-like episodes occur in autosomal recessively inherited congenital lactic acidoses as well as in those caused by mitochondrial DNA mutations. In some cases, acute localized neurovascular changes occur in regions that subsequently develop Leigh disease.

Genetic locus heterogeneity in Lafora's progressive myoclonus epilepsy.

In 1995, we mapped a gene for Lafora's progressive myoclonus epilepsy in chromosome 6q23-25. In 1997 and 1998, we reduced the size of the locus to 300 kb, and an international collaboration identified mutations in the protein tyrosine phosphatase gene. Here, we examine for heterogeneity through the admixture test in 22 families and estimate the proportion of linked families to be 75 to 85%. Extremely low posterior probabilities of linkage (Wi), exclusionary LOD scores, and haplotypes identify 4 families unlikely to be linked to chromosome 6q24.

Case study: dreamy state and temporal lobe dysfunction in a migrainous adolescent.

Symptoms of migraine can be very atypical during childhood and adolescence. This article describes a case in which the symptoms of migraine were mainly psychiatric: dreamy state, intermittent confusion, partial amnesia, and childlike regressive behavior with depressive features. Although the results from neurological examinations and electroencephalographic recordings were normal when the individual was symptomatic or not, temporal lobe dysfunction, determined by 99mTc-hexamethyl-propyleneamine oxamine single-photon emission computed tomography, was evident during the migraine.

Sound localization in hemispherectomized patients.

In order to precisely evaluate the consequences of cortical damage on free-field sound localization in humans, the present study examined response accuracy to auditory targets in three hemispherectomized patients and IQ-matched controls. Listeners reported sound location by pointing with their dominant hand to the apparent sound location in an anechoic chamber. Two conditions were tested: (i) localization of a fixed-sound source and (ii) localization of the beginning and the end of a simulated moving stimulus. In both conditions, the responses of the patients were less accurate than those of the controls in the hemifield contralateral to their removed hemisphere. Moreover, the single-case analyses revealed that the performances obtained with fixed sources were generally more precise than those obtained with moving sources. This result is discussed in terms of a differential involvement of cortical and subcortical pathways in the processing of stationary and moving sounds. Finally, the age at surgery and the post-surgical interval were related with the magnitude of the deficits, suggesting the possible influences of functional reorganization and cerebral plasticity.

Neurological findings in HIV-infected children: a review of 49 cases.

Many HIV-infected children have neurological involvement. We present our observations in 49 cases, 58% of which had some form of clinical neurological impairment. Most of the patients affected (71%) presented with progressive encephalopathy, characterized by developmental delay with loss of acquisitions and cognitive decline, an impaired growth curve, microcephaly and corticospinal dysfunction. CT-scan imaging shows cerebral atrophy in all cases and basal ganglia calcifications in 29%. Non-specific abnormalities are found on the EEG in two-thirds of cases and in the CSF in slightly less than half the cases. Pathological studies sometime revealed HIV encephalitis or lateral corticospinal tracts degeneration. Neurological impairment secondary to vascular events, neoplasms or opportunistic infections were rare, especially when compared with the adult HIV population.

Paediatric myelography with iohexol.

32 paediatric patients requiring myelography were studied with iohexol 210 mgI/ml (n = 15) and iohexol 180 mgI/ml (n = 17). Visualization was good or excellent in over 90% of the group receiving the higher concentration and in over 83% of the lower. There were no side effects in either group and vital signs were not significantly altered during the procedure. In the majority of patients (14/18) who had CT, additional diagnostic information was obtained. Iohexol 180 mgI/ml is preferred for routine use, but 210 mgI/ml may give superior visualization with no apparent added risk. Procedural technique and good communication with the patients and their families may have contributed to the absence of side effects.

Auditory lateralization for speech in language-impaired children.

The ability of five language-impaired (LI) children and five matched controls, aged 7-10 years, to discriminate natural pairs of consonant-vowel syllables contrasted on place of articulation and voicing, presented to the right or left ear with white noise in the contralateral ear, was investigated. The general pattern of errors indicated that LI children had more difficulty than controls in discriminating place of articulation contrasts only when they were presented to the left ear, as well as a difficulty in discriminating voice contrasts selective to the right ear. The results are discussed in terms of acoustic integration and suggest that bihemispheric dysfunction is a basis for specific language impairment.

Absence of disconnexion syndrome in callosal agenesis and early callosotomy: brain reorganization or lack of structural specificity during ontogeny?

Four acallosal subjects, one child, aged 5, and three adults, as well as five epileptic patients who underwent callosotomy between the ages of 6-21 years, were tested on a variety of intra- and intermanual tasks in a study aimed at elucidating the developmental aspects of callosal plasticity. The performance of the clinical sample was compared to that of 48 normal children, aged 5-12 years, an age span generally considered to coincide with the final stages of callosal maturation. As previously reported, interhemispheric integration improved with increasing age in the normal sample. The two patients having undergone callosotomy in childhood performed as well as their normal peers, whereas the three others who had the operation in late adolescence or adulthood showed the typical disconnexion deficits reported in the literature. The acallosal subjects, including the youngest one, outperformed all groups. We speculate that the remarkable plasticity seen in the acallosals and the young callosotomized patients may be related to a critical period in development coinciding with a phase of synaptic overproduction and redundancy that would favor the reinforcement of alternative neural pathways. The compensatory mechanisms appear to become more limited in late adolescence when synaptic distribution presumably assumes adult patterns.

Extent and limits of cerebral adjustment to early section or congenital absence of the corpus callosum.

The ability to effect inter- and intrahemispheric comparisons of visual and tactile stimuli was studied in 4 callosotomized patients and 6 callosal agenesis subjects using response accuracy and response times to determine the extent of cerebral adjustment to functional or congenital absence of the corpus callosum. The visual tasks involved within- and between-fields presentation of pairs of colours and shapes. The tactile tasks required uni- and bimanual comparisons of 3 categories of stimuli (size, shape and texture) of increasing difficulty. Older callosotomized children showed disconnection deficits similar to those reported in adult split-brain patients, whereas both acallosal subjects and our youngest patient with complete callosal transection demonstrated a high level of accuracy in the interhemispheric tasks. However, all patients required considerably more time to accomplish the cross-integration of relatively complex visual and tactile information which seems to be one of the major limitations of the compensatory mechanisms. The results also indicate that the quality of transfer differs between the acallosal and early-callosotomized patients in relation to the sensory modality studied. Thus, visual cross-matching was found to be superior to bimanual matching for the callosotomized group, whereas intermanual comparisons proved to be more efficient than visual integration in the acallosals. These divergent findings suggest not only that different compensatory mechanisms may be operating in visual and tactile transfer, but also that the same mechanisms may be utilized differently by the two populations deprived of the use of callosal connections.