Gamma-band synchronization in the macaque hippocampus and memory formation

Increasing evidence suggests that neuronal synchronization in the gamma band (30–100 Hz) may play an important role in mediating cognitive processes. Gamma-band synchronization provides for the optimal temporal relationship between two signals to produce the long-term synaptic changes that have been theorized to underlie memory formation. Although neuronal populations in the hippocampus oscillate in the gamma range, the role of these oscillations in memory formation is still unclear. To address this issue, we recorded neuronal activity in the hippocampus while macaque monkeys performed a visual recognition memory task. During the encoding phase of this task, hippocampal neurons displayed gamma-band synchronization. Additionally, enhanced gamma-band synchronization during encoding predicted greater subsequent recognition memory performance. These changes in synchronization reflect enhanced coordination among hippocampal neurons and may facilitate synaptic changes necessary for successful memory encoding

Feasibility study for a microwave-powered ozone sniffer aircraft

The preliminary design of a high-altitude, remotely-piloted, atmospheric-sampling aircraft powered by microwave energy beamed from ground-based antenna was completed. The vehicle has a gross weight of 6720 pounds and is sized to carry a 1000 pound payload at an altitude of 100,000 feet. The underside of the wing serves as the surface of a rectenna designed to receive microwave energy at a power density of 700 watts per square meter and the wing has a planform area of 3634 square feet to absorb the required power at an optimum Mach number M = 0.44. The aircraft utilizes a horizontal tail and a canard for longitudinal control and to enhance the structural rigidity of the twin fuselage configuration. The wing structure is designed to withstand a gust-induced load factor n = 3 at cruise altitude but the low-wing loading of the aircraft makes it very sensitive to gusts at low altitudes, which may induce load factors in excess of 20. A structural load alleviation system is therefore proposed to limit actual loads to the designed structural limit. Losses will require transmitted power on the order of megawatts to be radiated to the aircraft from the ground station, presenting environmental problems. Since the transmitting antenna would have a diameter of several hundred feet, it would not be readily transportable, so we propose that a single antenna be constructed at a site from which the aircraft is flown. The aircraft would be towed aloft to an initial altitude at which the microwave power would be utilized. The aircraft would climb to cruise altitude in a spiral flight path and orbit the transmitter in a gentle turn

Susceptibility of group A beta-hemolytic streptococci in the lower St Lawrence region, Quebec

A DesRosiers, P Dolcé, P Jutras, LP Jetté. Susceptibility of group A beta-hemolytic streptococci in the lower St Lawrence region, Quebec, Canada. Can J Infect Dis 1999;10(4):279-285. OBJECTIVE: To determine the susceptibility of group A beta-hemolytic streptococci (GABHS) in the lower St Lawrence region, Quebec to different antibiotics, particularly macrolides, and to compare different antibiogram methods (disk diffusion, E-test and microdilution) and incubation atmospheres (ambient air and 5% carbon dioxide). METHODS: A total of 384 strains of GABHS isolated from 377 patients (throat 335; other sites 49) from three hospitals in the lower St Lawrence region were analyzed for their susceptibility to erythromycin, clarithromycin, azithromycin, penicillin, clindamycin, cephalothin, rifampin and vancomycin by disk diffusion on Mueller-Hinton (MH) agar supplemented with 5% defibrinated sheep blood (MHB) at 35ºC in 5% carbon dioxide. Strains that were found to be intermediately resistant or resistant to one of the antibiotics by disc diffusion, strains from sites other than throat, and a sample of 97 pharyngeal strains were evaluated by E-test on MHB (35ºC, 5% carbon dioxide) for their susceptibility to the antibiotics erythromycin, clarithromycin, azithromycin, penicillin, clindamycin and ceftriaxone. In addition, minimum inhibitory concentrations (MICs) were determined for erythromycin and azithromycin by broth microdilution using MH broth supplemented with 2.5 % of lysed horse blood (35ºC, ambient air) on strains that were resistant or intermediately resistant to the macrolides (erythromycin, clarithromycin, azithromycin). An evaluation was also carried out on these strains to determine the influence of the incubating atmosphere (ambient air versus 5% carbon dioxide) on susceptibility results obtained by disk diffusion (erythromycin, clarithromycin and azithromycin) and E-test (erythromycin and azithromycin) methods. RESULTS: Nine strains (2%) from nine patients (throat eight, pus one) were resistant to all macrolides as tested by three different techniques (disk diffusion, E-test and microdilution). All strains were susceptible to all the other antibiotics tested. For the strains intermediately resistant or resistant to macrolides, incubation in a 5% carbon dioxide atmosphere was associated with a reduction in the diameter of inhibition determined by disk diffusion (P<0.001) with frequent minor variations in interpretation, and with an increase in the MIC by E-test (P<0.001), which had no impact on interpretation. CONCLUSIONS: Resistance of GABHS to macrolides was not common (2%) in the lower St Lawrence Region. GABHS susceptibility to erythromycin seemed to predict the susceptibility to the other macrolides. Significant variation in antibiogram results (disk diffusion and E-test) of GABHS susceptibility to macrolides was related to the incubation atmosphere and may have an impact on the interpretation of disk diffusion results. I n the past few years with the resurgence of invasive infections, group A beta-hemolytic streptococci (GABHS) have become a public health threat (1-8). Surveillance programs have been implemented in many countries. In Canada, in the province of Quebec, GABHS invasive infections became a notifiable disease in 1995 (unpublished data). In 1995, 11 cases of invasive GABHS infections occurred in the lower St Lawrence region (LSLR) of Quebec. This region, with a population of approximately 215,000 people, had an incidence rate of 5.1/100 000 cases/year, the highest in the province of Quebec. The overall incidence rate in Quebec was 1.4/100,000 cases/year (unpublished data). Pharyngitis is the most frequent clinical manifestation of GABHS infections, and it is believed that pharyngitis usually precedes invasive infections. Penicillin is the antibiotic of choice in the treatment of pharyngitis. Erythromycin is recommended as an alternative for patients allergic to penicillin (9,110). Recently, increasing resistance of GABHS to erythromycin and its derivatives has been observed in several countries. In Japan, the frequency of GABHS erythromycin resistance rose from 2% in 1971 to 50% to 70% in the 1990s (11-13). A resistance of nearly 40% was reported in certain areas of Finland in 1990 (14-16) and was associated with the level of regional erythromycin consumption. Erythromycin resistance dropped to 8.6% after a successful nationwide information and education program to reduce erythromycin consumption (17). Such high levels of resistance have not been reported in North America. For instance, the rate of erythromycin resistance is low in the United States: 5% and less, for studies published between 1968 and 1997 (11,18,19). Very few Canadian studies have addressed the issue of GABHS resistance to macrolides. In 1992, Knowles et al (20) found 2% erythromycin resistance among 492 GABHS isolates from clinical specimens gathered from in a children's hospital in Montreal. They also reported that, in comparison with ambient air, incubation under a 5% carbon dioxide atmosphere was associated with a significant increase in minimal inhibition concentration (MIC) for GABHS isolates to erythromycin and clarithromycin. A similar effect of incubation atmosphere was described by Brorson and Larsson (21). The aim of the present study was to determine the susceptibility level of GABHS to different antibiotics, particularly macrolides, in the LSLR. In addition, the study compared different antibiogram methods (disk diffusion, E-test and microdilution) and two incubation atmospheres (ambient air and 5% carbon dioxide) in a subset of isolates. MATERIALS AND METHODS GABHS strains: GABHS isolates were collected between March 1995 and February 1996 from three hospitals in the LSLR: the Centre Hospitalier Régional de Rimouski, the Centre Hospitalier d'Amqui and the Centre Hospitalier du Grand Portage. A maximum of two strains per patient were admissible: one strain from the throat and the other from a normally sterile site. 280 Can J Infect Dis Vol 10 No 4 July/August 1999 MÉTHODES : En tout, on a analysé 384 isolats de SBHGA provenant de 377 patients (gorge, 335; autres foyers, 49) de trois hôpitaux du Bas Saint-Laurent pour vérifier leur sensibilité à l'érythromycine, à la clarithromycine, à l'azithromycine, à la pénicilline, à la clindamicyne, à la céphalothine, au rifampim et à la vancomycine, par diffusion en gélose de Mueller-Hinton (MH) enrichie de sang de mouton à 5 % défibriné (SMD), à 35°C, dans du dioxyde de carbone à 5 %. Les souches qui se sont révélées résistantes ou moyennement résistantes à l'un des antibiotiques par la méthode de diffusion en gélose, les souches provenant d'autres foyers que la gorge et un échantillon de 97 isolats pharyngés ont été éva-lués par test E sur SMD (35°C, dioxyde de carbone à 5 %) pour en mesurer la sensibilité à l'endroit des antibiotiques érythromycine, clarithromycine, azithromycine, pénicilline, clindamycine et ceftriaxone. De plus, les concentrations minimales inhibitrices (CMI) ont été calculées pour l'érythromycine et l'azithromycine par microdilution sur bouillon de culture, à l'aide de solutions MH auxquelles a été ajouté du sang de cheval à 2,5 % lysé (35°C, air ambiant), sur des souches qui se sont révélées résistantes ou moyennement résistantes à l'endroit des macrolides (érythromycine, clarithromycine, azithromycine). Une évaluation a en outre été effectuée sur ces souches afin de déterminer l'influence de l'atmosphère d'incubation (air ambiant vs dioxyde de carbone à 5 %) sur les résultats d'antibiogrammes obtenus par diffusion en gélose (érythromycine, clarithromycine et azithromycine) et test E (érythromycine et azithromycine). RÉSULTATS : Neuf souches (2 %) provenant de neuf patients (8 prélèvements de gorge, 1 spécimen de pus) se sont révé-lées résistantes à tous les macrolides testés au moyen des trois techniques (diffusion en gélose, test E et microdilution). La totalité des souches se sont révélées sensibles à tous les autres antibiotiques testés. Pour les souches résistantes ou moyennement résistantes aux macrolides, l'incubation dans une atmosphère de dioxyde de carbone à 5 % a été associée à une réduction du diamètre d'inhibition, déterminée par la méthode de diffusion en gélose (p < 0,001), avec fréquentes variations mineures des interprétations et augmentation de la CMI selon le test E (p < 0,001), qui n'ont eu aucun impact sur l'interprétation de ces résultats. CONCLUSIONS : La résistance des SBHGA à l'endroit des macrolides n'a pas été fréquente (2 %) dans le Bas Saint-Laurent. Leur sensibilité à l'érythromycine a semblé être un facteur de prévisibilité de leur sensibilité aux autres macrolides. La variabilité significative des résultats d'antibiogrammes (diffusion en gélose et test E), du degré de sensibilité des SBHGA à l'endroit des macrolides a été jugée en lien avec l'atmosphère d'incubation et pourrait exercer un impact sur l'interprétation des résultats obtenus au moyen de la technique par diffusion en gélose. Statistical analysis: Data were analyzed on EPI INFO, version 6.0 (Atlanta, Georgia). The influence of the incubation atmosphere (ambient air versus carbon dioxide) was determined by ANOVA with a significance level of P<0.05 using SYSTAT software, version 5.02 (Systat Inc, Evanston, Illinois). Conservation and reidentification: Review of the medical files: The medical files of patients with strains resistant or intermediately resistant to macrolides were reviewed to obtain any pertinent clinical data. RESULTS A total of 384 GABHS strains isolated from 377 patients (throat 335 [87%], other sites 49 [13%]) were examined (Table 1). Seven patients had two isolates: one from the throat and the second from another site (wound four, fascia two, joint liquid one). Fifteen of the 49 nonpharyngeal strains were isolated in patients with invasive infections. The re-identification of all 384 strains confirmed them to be S pyogenes. Only six isolates yielded unexpected results; all exhibited trimethoprim/sulphamethoxazole susceptibility. In these cases, seroagglutination with group A antigen gave positive results

BpaB, a novel protein encoded by the Lyme disease spirochete’s cp32 prophages, binds to erp Operator 2 DNA

Borrelia burgdorferi produces Erp outer surface proteins throughout mammalian infection, but represses their synthesis during colonization of vector ticks. A DNA region 5′ of the start of erp transcription, Operator 2, was previously shown to be essential for regulation of expression. We now report identification and characterization of a novel erp Operator 2-binding protein, which we named BpaB. erp operons are located on episomal cp32 prophages, and a single bacterium may contain as many as 10 different cp32s. Each cp32 family member encodes a unique BpaB protein, yet the three tested cp32-encoded BpaB alleles all bound to the same DNA sequence. A 20-bp region of erp Operator 2 was determined to be essential for BpaB binding, and initial protein binding to that site was required for binding of additional BpaB molecules. A 36-residue region near the BpaB carboxy terminus was found to be essential for high-affinity DNA-binding. BpaB competed for binding to erp Operator 2 with a second B. burgdorferi DNA-binding protein, EbfC. Thus, cellular levels of free BpaB and EbfC could potentially control erp transcription levels

BpaB, a Novel Protein Encoded by the Lyme Disease Spirochete\u27s Cp32 Prophages, Binds to Erp Operator 2 DNA

Borrelia burgdorferi produces Erp outer surface proteins throughout mammalian infection, but represses their synthesis during colonization of vector ticks. A DNA region 5′ of the start of erp transcription, Operator 2, was previously shown to be essential for regulation of expression. We now report identification and characterization of a novel erp Operator 2-binding protein, which we named BpaB. erp operons are located on episomal cp32 prophages, and a single bacterium may contain as many as 10 different cp32s. Each cp32 family member encodes a unique BpaB protein, yet the three tested cp32-encoded BpaB alleles all bound to the same DNA sequence. A 20-bp region of erp Operator 2 was determined to be essential for BpaB binding, and initial protein binding to that site was required for binding of additional BpaB molecules. A 36-residue region near the BpaB carboxy terminus was found to be essential for high-affinity DNA-binding. BpaB competed for binding to erp Operator 2 with a second B. burgdorferi DNA-binding protein, EbfC. Thus, cellular levels of free BpaB and EbfC could potentially control erp transcription levels

Evidence for Human Fronto-Central Gamma Activity during Long-Term Memory Encoding of Word Sequences

Although human gamma activity (30–80 Hz) associated with visual processing is often reported, it is not clear to what extend gamma activity can be reliably detected non-invasively from frontal areas during complex cognitive tasks such as long term memory (LTM) formation. We conducted a memory experiment composed of 35 blocks each having three parts: LTM encoding, working memory (WM) maintenance and LTM retrieval. In the LTM encoding and WM maintenance parts, participants had to respectively encode or maintain the order of three sequentially presented words. During LTM retrieval subjects had to reproduce these sequences. Using magnetoencephalography (MEG) we identified significant differences in the gamma and beta activity. Robust gamma activity (55–65 Hz) in left BA6 (supplementary motor area (SMA)/pre-SMA) was stronger during LTM rehearsal than during WM maintenance. The gamma activity was sustained throughout the 3.4 s rehearsal period during which a fixation cross was presented. Importantly, the difference in gamma band activity correlated with memory performance over subjects. Further we observed a weak gamma power difference in left BA6 during the first half of the LTM rehearsal interval larger for successfully than unsuccessfully reproduced word triplets. In the beta band, we found a power decrease in left anterior regions during LTM rehearsal compared to WM maintenance. Also this suppression of beta power correlated with memory performance over subjects. Our findings show that an extended network of brain areas, characterized by oscillatory activity in different frequency bands, supports the encoding of word sequences in LTM. Gamma band activity in BA6 possibly reflects memory processes associated with language and timing, and suppression of beta activity at left frontal sensors is likely to reflect the release of inhibition directly associated with the engagement of language functions

Cannabis-Dependence Risk Relates to Synergism between Neuroticism and Proenkephalin SNPs Associated with Amygdala Gene Expression: Case-Control Study

BACKGROUND:Many young people experiment with cannabis, yet only a subgroup progress to dependence suggesting individual differences that could relate to factors such as genetics and behavioral traits. Dopamine receptor D2 (DRD2) and proenkephalin (PENK) genes have been implicated in animal studies with cannabis exposure. Whether polymorphisms of these genes are associated with cannabis dependence and related behavioral traits is unknown. METHODOLOGY/PRINCIPAL FINDINGS:Healthy young adults (18-27 years) with cannabis dependence and without a dependence diagnosis were studied (N = 50/group) in relation to a priori-determined single nucleotide polymorphisms (SNPs) of the DRD2 and PENK genes. Negative affect, Impulsive Risk Taking and Neuroticism-Anxiety temperamental traits, positive and negative reward-learning performance and stop-signal reaction times were examined. The findings replicated the known association between the rs6277 DRD2 SNP and decisions associated with negative reinforcement outcomes. Moreover, PENK variants (rs2576573 and rs2609997) significantly related to Neuroticism and cannabis dependence. Cigarette smoking is common in cannabis users, but it was not associated to PENK SNPs as also validated in another cohort (N = 247 smokers, N = 312 non-smokers). Neuroticism mediated (15.3%-19.5%) the genetic risk to cannabis dependence and interacted with risk SNPs, resulting in a 9-fold increase risk for cannabis dependence. Molecular characterization of the postmortem human brain in a different population revealed an association between PENK SNPs and PENK mRNA expression in the central amygdala nucleus emphasizing the functional relevance of the SNPs in a brain region strongly linked to negative affect. CONCLUSIONS/SIGNIFICANCE:Overall, the findings suggest an important role for Neuroticism as an endophenotype linking PENK polymorphisms to cannabis-dependence vulnerability synergistically amplifying the apparent genetic risk

The Multicultural Classroom as a Comparative Law Site: A United Kingdom Perspective

This chapter studies the impact of the recent multicultural approach to comparative legal studies on comparative law teaching, with a focus on British debates and literature. I will argue that the multicultural turn of (comparative) legal teaching, reflected for example in a greater diversity of teaching techniques, a greater emphasis on minority issues and law &… disciplines, responds to a multiplicity of motivations. Pedagogically, it is a response to the increasingly diverse backgrounds of students and their differing intellectual starting-points. Pragmatically, it is a means to boost students’ employability and intellectual versality in a job market that now values “cultural awareness skills”. Finally, conceptually, it is a tool designed to unravel the pluralistic nature of law. From these diverse drivers to the multicultural turn in (comparative) legal teaching, it is possible to identify similarities with other recent trends of globalisation and internationalisation of legal education. However, this article will submit that differences remain. Having analysed these differences, I will go on to argue and reveal that in them lie the core features of a multicultural approach to legal teaching and its intrinsic connections to comparative law, as the multicultural classroom itself becomes a comparative law site

A summer heat wave decreases the immunocompetence of the mesograzer, Idotea baltica

Extreme events associated with global change will impose increasing stress on coastal organisms. How strong biological interactions such as the host–parasite arms-race are modulated by environmental change is largely unknown. The immune system of invertebrates, in particular phagocytosis and phenoloxidase activity response are key defence mechanisms against parasites, yet they may be sensitive to environmental perturbations. We here simulated an extreme event that mimicked the European heat wave in 2003 to investigate the effect of environmental change on the immunocompetence of the mesograzer Idotea baltica. Unlike earlier studies, our experiment aimed at simulation of the natural situation as closely as possible by using long acclimation, a slow increase in temperature and a natural community setting including the animals’ providence with natural food sources (Zostera marina and Fucus vesiculosus). Our results demonstrate that a simulated heat wave results in decreased immunocompetence of the mesograzer Idotea baltica, in particular a drop of phagocytosis by 50%. This suggests that global change has the potential to significantly affect host–parasite interactions