Modulation of cerebellar purkinje cell activity with low intensity electric and ultrasound stimulation

Non-invasive brain stimulation (NIBS) techniques garner significant interest due to their potential to offer instantaneous and region-specific treatments to neurological disorders. The cerebellum is one of the target sites for NIBS methods due to its central role in motor and cognitive functions. Among several modulation techniques, transcranial electric stimulations (tEs), in particular, transcranial direct and alternating current stimulations (tDCs/tACs), and low intensity focused ultrasound stimulation (LIFUS) show encouraging outcomes in clinical applications. tDCs and tACs are favored due to their low cost and accessibility while LIFUS offers high spatial resolution and deeper penetration without affecting the surrounding structures. In order to better understand the underlying mechanism of these methods in the cerebellum, animal studies are needed since these experiments require invasive surgeries. The goal of this study is to investigate the response of cerebellar PCs to electric and ultrasound stimulation in an animal model. The first objective is to measure the electric field (e-field) distribution inside the brain parenchyma since e-field is the main parameter that determines the local effects of electrical stimulation. The results of this part show that e-field decays exponentially through horizontal and vertical directions from the stimulating electrode and scattered by the skin up to 80%. Then, tACS and tDCS are applied to the cerebellar cortex respectively while recording the extracellular spike activity from the cerebellar PCs. The activity of PCs is important because they generate the sole output from the cerebellar cortex, which in turn modifies the output of the deep cerebellar nuclei (DCN). The results of this part demonstrate that the direction of e-field is highly correlated with the level of modulation measured on the PCs. Applying the e-field parallel to the dendritic tree of the PCs generates the highest modulation level. Our data show that PCs have a characteristic response to both DC and AC fields, including entrainment of the simple spike activity at high frequencies. Our findings for the LIFUS also show that spike timing of PCs is strongly entrained with the pulsed ultrasound stimulation, and the level of the entrainment is inversely correlated with the pulse width. In summary, the low intensity electric and ultrasound stimulation are able to effectively modulate the PC activity in the cerebellar cortex. This warrants research to further look into the mechanism of tES and LIFUS acting on the cerebellar cortex at the cellular level

Systemic and local antibiotic prophylaxis in the prevention of Staphylococcus epidermidis graft infection

BACKGROUND: The aim of the study was to investigate the in vivo efficacy of local and systemic antibiotic prophylaxis in the prevention of Staphylococcus (S.) epidermidis graft infection in a rat model and to evaluate the bacterial adherence to frequently used prosthetic graft materials. METHODS: Graft infections were established in the subcutaneous tissue of 120 male Wistar rats by implantation of Dacron/ePTFE grafts followed by topical inoculation with 2 × 10(7 )CFUs of clinical isolate of methicillin-resistant S. epidermidis. Each of the graft series included a control group, one contaminated group that did not receive any antibiotic prophylaxis, two contaminated groups that received systemic prophylaxis with teicoplanin or levofloxacin and two contaminated groups that received teicoplanin-soaked or levofloxacin-soaked grafts. The grafts were removed 7 days after implantation and evaluated by quantitative culture. RESULTS: There was significant bacterial growth inhibition in the groups given systemic or local prophylaxis (P < 0.05). Methicillin-resistant S. epidermidis had greater affinity to Dacron graft when compared with ePTFE graft in the untreated contaminated groups (P < 0.05). CONCLUSION: The study demonstrated that the usage of systemic or local prophylaxis and preference of ePTFE graft can be useful in reducing the risk of vascular graft infections caused by staphylococcal strains with high levels of resistance

The Amsterdam Declaration on Fungal Nomenclature

The Amsterdam Declaration on Fungal Nomenclature was agreed at an international symposium convened in Amsterdam on 19–20 April 2011 under the auspices of the International Commission on the Taxonomy of Fungi (ICTF). The purpose of the symposium was to address the issue of whether or how the current system of naming pleomorphic fungi should be maintained or changed now that molecular data are routinely available. The issue is urgent as mycologists currently follow different practices, and no consensus was achieved by a Special Committee appointed in 2005 by the International Botanical Congress to advise on the problem. The Declaration recognizes the need for an orderly transitition to a single-name nomenclatural system for all fungi, and to provide mechanisms to protect names that otherwise then become endangered. That is, meaning that priority should be given to the first described name, except where that is a younger name in general use when the first author to select a name of a pleomorphic monophyletic genus is to be followed, and suggests controversial cases are referred to a body, such as the ICTF, which will report to the Committee for Fungi. If appropriate, the ICTF could be mandated to promote the implementation of the Declaration. In addition, but not forming part of the Declaration, are reports of discussions held during the symposium on the governance of the nomenclature of fungi, and the naming of fungi known only from an environmental nucleic acid sequence in particular. Possible amendments to the Draft BioCode (2011) to allow for the needs of mycologists are suggested for further consideration, and a possible example of how a fungus only known from the environment might be described is presented

Electrical fields induced inside the rat brain with skin, skull, and dural placements of the current injection electrode.

Transcranial electrical stimulation (tES) is rapidly becoming an indispensable clinical tool with its different forms. Animal data are crucially needed for better understanding of the underlying mechanisms of tES. For reproducibility of results in animal experiments, the electric fields (E-Fields) inside the brain parenchyma induced by the injected currents need to be predicted accurately. In this study, we measured the electrical fields in the rat brain perpendicular to the brain surface, i.e. vertical electric field (VE-field), when the stimulation electrode was placed over the skin, skull, or dura mater through a craniotomy hole. The E-field attenuation through the skin was a few times larger than that of the skull and the presence of skin substantially reduced the VE-field peak at the cortical surface near the electrode. The VE-field declined much quicker in the gray matter underneath the pial surface than it did in the white matter, and thus the large VE-fields were contained mostly in the gray matter. The transition at the gray/white matter border caused a significant peak in the VE-field, as well as at other local inhomogeneties. A conductivity value of 0.57 S/m is predicted as a global value for the whole brain by matching our VE-field measurements to the field profile given by analytical equations for volume conductors. Finally, insertion of the current return electrode into the shoulder, submandibular, and hind leg muscles had virtually no effects on the measured E-field amplitudes in the cortex underneath the epidural electrodes

Modulation of cerebellar cortical, cerebellar nuclear and vestibular nuclear activity using alternating electric currents

IntroductionCerebellar transcranial alternating current stimulation (ctACS) has shown promise as a therapeutic modality for treating a variety of neurological disorders, and for affecting normal learning processes. Yet, little is known about how electric fields induced by applied currents affect cerebellar activity in the mammalian cerebellum under in vivo conditions.MethodsAlternating current (AC) stimulation with frequencies from 0.5 to 20 Hz was applied to the surface of the cerebellum in anesthetized rats. Extracellular recordings were obtained from Purkinje cells (PC), cerebellar and vestibular nuclear neurons, and other cerebellar cortical neurons.Results and discussionAC stimulation modulated the activity of all classes of neurons. Cerebellar and vestibular nuclear neurons most often showed increased spike activity during the negative phase of the AC stimulation. Purkinje cell simple spike activity was also increased during the negative phase at most locations, except for the cortex directly below the stimulus electrode, where activity was most often increased during the positive phase of the AC cycle. Other cortical neurons showed a more mixed, generally weaker pattern of modulation. The patterns of Purkinje cell responses suggest that AC stimulation induces a complex electrical field with changes in amplitude and orientation between local regions that may reflect the folding of the cerebellar cortex. Direct measurements of the induced electric field show that it deviates significantly from the theoretically predicted radial field for an isotropic, homogeneous medium, in both its orientation and magnitude. These results have relevance for models of the electric field induced in the cerebellum by AC stimulation

Comparison of antimicrobial agents as therapy for experimental endocarditis

We used an experimental rat model to compare the therapeutic efficacy of teicoplanin, linezolid, and quinupristin/dalfopristin with that of vancomycin as standard therapy for infective endocarditis. Aortic endocarditis was induced in rats by insertion of a polyethylene catheter into the left ventricle, followed by intravenous inoculation of 106 colony-forming units of methicillin-resistant Staphylococcus aureus 24 hours later. Forty-eight hours after bacterial challenge, intravenous antibiotic therapies were initiated. There were 6 groups of 8 rats each: uninfected control; infected, untreated control; vancomycin-treated (40 mg/kg twice daily); teicoplanin-treated (20 mg/kg twice daily after a loading dose of 40 mg/kg); linezolid-treated (75 mg/kg 3 times daily for 1 day, then 75 mg/kg twice daily); and quinupristin/dalfopristintreated (30 mg/kg twice daily and an additional 10 mg/kg dalfopristin infusion over 6 to 12 hr daily). At the end of therapy, the aortic valve vegetations in the drug-treated rats were evaluated microbiologically. Compared with the infected, untreated group, all drug-treated groups had significantly reduced bacterial titers in the vegetations. Vancomycin, teicoplanin, and quinupristin/dalfopristin all effectively reduced the quantitative bacterial cultures of aortic valve vegetations. In addition, there was no significant difference in the comparative efficacy of teicoplanin, linezolid, and quinupristin/dalfopristin. Vancomycin significantly reduced bacterial counts in comparison with linezolid, which was nonetheless also effective. Our experimental model showed that each of the investigated antimicrobial agents was effective in the treatment of infective endocarditis. © 2010 by the Texas Heart® Institute, Houston

Kültürel Bellek 2017

KÜLTÜREL BELLEK 2017 kitabımızda, 7-8-9 Kasım 2017'de üniversitemizin Bilimsel Araştırma Projeleri Koordinasyon Birimi'nin desteğiyle gerçekleştirdiğimiz sempozyumdan seçilmiş yazılar ve konuyla ilgili olduğunu düşündüğümüz araştırma yazıları toplanmıştır. Başta Hacettepe Üniversitesi olmak üzere Ankara Üniversitesi, Anadolu Üniversitesi, Orta Doğu Teknik Üniversitesi, Hacı Bayram Veli Üniversitesi, TED Üniversitesi, Çankaya Üniversitesi gibi Ankara'daki üniversiteler ile Tekirdağ Üniversitesi, Zonguldak Bülent Ecevit Üniversitesi, Balıkesir Üniversitesi, Nevşehir Üniversitesi, Sakarya Üniversitesi, Özyeğin Üniversitesi gibi ülkemizin farklı kentlerindeki üniversitelerden ve Varşova Üniversitesi'nden araştırmacıların çalışmalarını biraraya getirmekten mutluyuz. Disiplinlerarası yaklaşımı ve farklı bakış açılarını birleştirmeyi amaçladığımız bu seçkide sanat tarihi, psikoloji, halkbilimi, arkeoloji gibi insani bilimler alanlarından, Türk dili ve edebiyatı, Fransız dili ve edebiyatı, İngiliz dili ve edebiyatı, İtalyan dili ve edebiyatı gibi filoloji alanlarından, seramik, mimarlık, şehir ve bölge planlama gibi güzel sanatlar ve mimarlık fakültelerinden, psikiyatri ve nöroloji gibi tıp alanlarından araştırma yazıları yer almaktadır. Unutmamak için biz hatırlamayı, öğrenmeyi, görmeyi, araştırmayı seçiyoruz. Unutmamak için, unutulduysa hatırlamak ve hatırlatmak için, bilmeyenlere göstermek, anlatmak ve belleğimize sahip çıkmak için başladığımız bu yolculukta çağrımızı kırmayan değerli araştırmacılara şükranlarımızı sunuyoruz. Unutmayalım ki, kültürel bellek hepimizi birleştiren güçtür