Non-invasive transcranial ultrasound stimulation for neuromodulation.

Transcranial ultrasound stimulation (TUS) holds great potential as a tool to alter neural circuits non-invasively in both animals and humans. In contrast to established non-invasive brain stimulation methods, ultrasonic waves can be focused on both cortical and deep brain targets with the unprecedented spatial resolution as small as a few cubic millimeters. This focusing allows exclusive targeting of small subcortical structures, previously accessible only by invasive deep brain stimulation devices. The neuromodulatory effects of TUS are likely derived from the kinetic interaction of the ultrasound waves with neuronal membranes and their constitutive mechanosensitive ion channels, to produce short term and long-lasting changes in neuronal excitability and spontaneous firing rate. After decades of mechanistic and safety investigation, the technique has finally come of age, and an increasing number of human TUS studies are expected. Given its excellent compatibility with non-invasive brain mapping techniques, such as electroencephalography (EEG) and functional magnetic resonance imaging (fMRI), as well as neuromodulatory techniques, such as transcranial magnetic stimulation (TMS), systemic TUS effects can readily be assessed in both basic and clinical research. In this review, we present the fundamentals of TUS for a broader audience. We provide up-to-date information on the physical and neurophysiological mechanisms of TUS, available readouts for its neural and behavioral effects, insights gained from animal models and human studies, potential clinical applications, and safety considerations. Moreover, we discuss the indirect effects of TUS on the nervous system through peripheral co-stimulation and how these confounding factors can be mitigated by proper control conditions.

Shakeoff Ionization near the Coulomb Barrier Energy.

We measure the projectile K x-ray spectra as a function of the beam energies around the Coulomb barrier in different collision systems. The energy is scanned in small steps around the barrier aiming to explore the nuclear effects on the elastically scattered projectile ions. The variation of the projectile x-ray energy with the ion-beam energies exhibits an unusual increase in between the interaction barrier and fusion barrier energies. This additional contribution to the projectile ionization can be attributed to the shakeoff of outer-shell electrons of the projectile ions due to the sudden nuclear recoil (∼10^{-21} sec) caused by the attractive nuclear potential, which gets switched on near the interaction barrier energy. In the sudden approximation limit, the theoretical shakeoff probability calculation due to the nuclear recoil explains the observed data well. In addition to its fundamental interest, such processes can play a significant role in dark matter detection through the possible mechanism of x-ray emissions, where the weakly interacting massive particle-nucleus elastic scattering can lead to the nuclear-recoil-induced inner-shell vacancy creations. Furthermore, the present work may provide new prospects for atomic physics research at barrier energies as well as provide a novel technique to perform barrier distribution studies for two-body systems.

Note: Multi channel Doppler tuned spectrometer to study highly charged ions.

We describe the design and implementation of a multi channel Doppler tuned spectrometer setup to study physics of highly charged ions at high resolution in a direct way. A unique Soller slit assembly coupled with a long one dimensional position sensitive proportional counter enables us to get distinct x-ray peaks at different angles, which allows us to cover large number of angle in one shot. By using this setup, 1s2s (3)S1 - 1s(2) (1)S0 M1 transition in He-like Fe has been resolved from its satellite line 1s2s2p 4P(5/2)° - 1s(2)2s (2)S(1/2) M2 transition in Li-like Fe and measured the lifetime of their respective upper levels with high precision.

Profile of Patients with Allergic Rhinitis (AR): A Clinic Based Cross-Sectional Study from Kolkata, India.

BACKGROUND: Allergic Rhinitis (AR) though quite common in India, does not receive its due importance as it deserves. AIM OF THE STUDY: To identify the demographic and clinical profile of the patients with AR and to find the association of pre-dominant disease symptoms with common allergens, type and severity of the disease and other co-morbidities. SETTINGS AND DESIGN: This clinic-based cross-sectional, observational study was conducted among adult patients presenting with signs and symptoms suggestive of AR. METHODS AND MATERIAL: Consecutive 548 patients were initially screened for possible cases of AR by proper history taking and physical examination and confirmation was done by a battery of investigations, including modified skin prick test. A total of 462 patients who were finally diagnosed with AR were included in the study. Categorization of these patients was done following Allergic Rhinitis and its Impact on Asthma (ARIA) guidelines. Pulmonary function tests and X-ray/CT-scan of the para-nasal sinuses were done to confirm the presence of bronchial asthma and sinusitis, respectively. STATISTICAL ANALYSIS USED: Data were analyzed by Statistical Package for Social Scientists (SPSS version 10). Z-test was applied to compare between two rates, at 5% level of significance. RESULTS: Proportion of "blockers" was found to be much higher than that of "sneezers-runners" (64.1% vs. 35.9%). "Blockers" had significantly more sensitization to polyvalent house dust, house dust mites and fungi (p < 0.05), while, "sneezers-runners" had more sensitization to pollens (p < 0.05). Significantly more "blockers" had "moderate/severe persistent" and "mild persistent" types of the disease (p < 0.05), while "mild intermittent" and moderate/severe intermittent" type of disease were significantly more common among "sneezers-runners" (p < 0.05). Both bronchial asthma and sinusitis were significantly more common among the "blockers" (p < 0.05). CONCLUSION: It can be concluded from the present study that the clinical profiles of the two main categories of AR namely "sneezers-runners" and "blockers" were distinct from each other. This knowledge can be useful to physicians at all levels for better management of patients with AR.

Fast ion surface energy loss and straggling in the surface wake fields.

We have measured the stopping powers and straggling of fast, highly ionized atoms passing through thin bilayer targets made up of metals and insulators. We were surprised to find that the energy losses as well as the straggling depend on the ordering of the target and have small but significantly different values on bilayer reversal. We ascribe this newly found difference in energy loss to the surface energy loss field effect due to the differing surface wake fields as the beam exits the target in the two cases. This finding is validated with experiments using several different projectiles, velocities, and bilayer targets. Both partners of the diatomic molecular ions also display similar results. A comparison of the energy loss results with those of previous theoretical predictions for the surface wake potential for fast ions in solids supports the existence of a self-wake.

Molecular modeling of the ternary complex of Rusticyanin-cytochrome c4-cytochrome oxidase: an insight to possible H-bond mediated recognition and electron transfer reaction in T. ferrooxidans.

The metabolism of Thiobacillus ferrooxidans involves electron transfer from the Fe+2 ions in the extracellular environment to the terminal oxygen in the bacterial cytoplasm through a series of periplasmic proteins like Rusticyanin (RCy), Cytochrome (Cyt c4), and Cytochrome oxidase (CcO). The energy minimization and MD studies reveal the stabilization of the three redox proteins in their ternary complex through the direct and water mediated H-bonds and electrostatic interaction. The surface exposed polar residues of the three proteins, i.e., RCy (His 143, Thr 146, Lys 81, Glu 20), Cyt c4 (Asp 5, 15, 52, Ser 14, Glu 61), and CcO (Asp 135, Glu 126, 140, 142, Thr 177) formed the intermolecular hydrogen bonds and stabilized the ternary complex. The oxygen (Oepsilon1) of Glu 126, 140, and 142 on subunit II of the CcO interact to the exposed side-chain and Ob atoms of the Asp 52 of Cyt c4 and Glu 20 and Leu 12 of RCy. The Asp 135 of subunit II also forms H-bond with the Nepsilon atom of Lys 81 of RCy. The Oepsilon1 of Glu 61 of Cyt c4 is also H-bonded to Ogamma atom of Thr 177 of CcO. Solvation followed by MD studies of the ternary protein complex revealed the presence of seven water molecules in the interfacial region of the interacting proteins. Three of the seven water molecules (W 79, W 437, and W 606) bridged the three proteins by forming the hydrogen bonded network (with the distances approximately 2.10-2.95 A) between the Lys 81 (RCy), Glu 61 (Cyt c4), and Asp 135 (CcO). Another water molecule W 603 was H-bonded to Tyr 122 (CcO) and interconnected the Lys 81 (RCy) and Asp 135 (CcO) through the water molecules W 606 and W 437. The other two water molecules (W 21 and W 455) bridged the RCy to Cyt c4 through H-bonds, whereas the remaining W 76 interconnected the His 53 (Cytc4) to Glu 126 (CcO) with distances approximately 2.95-3.0 A.

Modeling study of Rusticyanin-Cytochrome C(4) complex: an insight to possible H-bond mediated recognition and electron--transfer process.

Rusticyanin (RCy) mediated transfer of electron to Cytochrome C(4) (Cytc(4)) from the extracellular Fe(+2) ion is primarily involved in the Thiobacillus ferrooxidans induced bio-leaching of pyrite ore and also in the metabolism of this acidophilic bacteria. The modeling studies have revealed the two possible mode of RCy-Cytc(4) complexation involving nearly the same stabilization energy approximately -15 x 10(3) kJ/mol, one through N-terminal Asp 15 and another -C terminal Glu 121 of Cytc(4) with the Cu-bonded His 143 of RCy. The Asp 15:His 143 associated complex (DH) of Cytc(4)-RCy was stabilized by the intermolecular H-bonds of the carboxyl oxygen atoms O(delta1) and O(delta2) of Asp 15 with the Nepsilon-atom of His 143 and O(b) atoms of Ala 8 and Asp 5 (of Cytc(4)) with the Thr 146 and Phe 51 (of RCy). But the other Glu 121:His 143 associated complex (EH) of Cytc(4)-RCy was stabilized by the H-bonding interaction of the oxygen atoms O(epsilon1) and O(epsilon2) of Glu 121 with the Nepsilon and Ogamma atoms of His 143 and Thr 146 of RCy. The six water molecules were present in the binding region of the two proteins in the energy minimized autosolvated DH and EH-complexes. The MD studies also revealed the presence of six interacting water molecules at the binding region between the two proteins in both the complexes. Several residues Gly 82 and 84, His 143 (RCy) were participated through the water mediated (W 389, W 430, W 413, W 431, W 373, and W 478) interaction with the Asp 15, Ile 82, and 62, Tyr 63 (Cytc(4)) in DH complex, whereas in EH complex the Phe 51, Asn 80, Tyr 146 (RCy) residues were observed to interact with Asn 108, Met 120, Glu 121 (of Cytc(4)) through the water molecules W 507, W 445, W 401, W 446, and W 440. The direct water mediated (W 478) interaction of His 143 (RCy) to Asp 15 (of Cytc(4)) was observed only in the DH complex but not in EH. These direct and water mediated H-bonding between the two respective proteins and the binding free energy with higher interacting buried surface area of the DH complex compare to other EH complex have indicated an alternative possibility of the electron transfer route through the interaction of His 143 of RCy and the N-terminal Asp 15 of Cytc(4).

Synovial sarcoma of parapharyngeal and retropharyngeal space: A case report.

Synovial sarcoma is a rare tumour of head and neck. It was first described by Pack and Ariel in 1950. Synovial sarcoma is said to be the commonest sarcoma of hands and feet and they are usually found adjacent to the articular surfaces. They rarely occur in extra-articular sites originating from bursa or tendon sheaths. Parapharyngeal space appears to be the site of predilection in most of the cases occurring in the head and neck region. One such case is being reported here along with its management and review of literature.

Juvenile nasopharyngeal angiofibroma-three years experience.

Juvenile nasopharyngeal angiofibroma is a rare, highly vascular, histologically benign but locally invasive tumour, affecting almost exclusively adolescent males. This is a prospective study of 37 patients with juvenile nasopharyngeal angiofibroma treated during 3 years in our institution. The various pharyngeal and extrapharyngeal presentation staging and proper surgical approaches as per extensions are discussed here with reference to past reports.

Juvenile nasopharyngeal angiofibromas with unique extrapharyngeal extensions.

From June 1999 to May 2000, 13 canes of Juvenile nasopharyngeal angiofibroma were diagnosed and treated in our department. From this series, 3 cases are highlighted here for their unusual extrapharyngeal presentation. Bio-mechanisms of these spreads are described. Management protocols are also discussed for these difficult cases.