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Search Results: 1 - 10 of 252 matches for " Nahum Meller "
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Integrin β3 Crosstalk with VEGFR Accommodating Tyrosine Phosphorylation as a Regulatory Switch
Xiaoxia Z. West, Nahum Meller, Nikolay L. Malinin, Lalit Deshmukh, Julia Meller, Ganapati H. Mahabeleshwar, Malory E. Weber, Bethany A. Kerr, Olga Vinogradova, Tatiana V. Byzova
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0031071
Abstract: Integrins mediate cell adhesion, migration, and survival by connecting intracellular machinery with the surrounding extracellular matrix. Previous studies demonstrated the importance of the interaction between β3 integrin and VEGF type 2 receptor (VEGFR2) in VEGF-induced angiogenesis. Here we present in vitro evidence of the direct association between the cytoplasmic tails (CTs) of β3 and VEGFR2. Specifically, the membrane-proximal motif around 801YLSI in VEGFR2 mediates its binding to non-phosphorylated β3CT, accommodating an α-helical turn in integrin bound conformation. We also show that Y747 phosphorylation of β3 enhances the above interaction. To demonstrate the importance of β3 phosphorylation in endothelial cell functions, we synthesized β3CT-mimicking Y747 phosphorylated and unphosphorylated membrane permeable peptides. We show that a peptide containing phospho-Y747 but not F747 significantly inhibits VEGF-induced signaling and angiogenesis. Moreover, phospho-Y747 peptide exhibits inhibitory effect only in WT but not in β3 integrin knock-out or β3 integrin knock-in cells expressing β3 with two tyrosines substituted for phenylalanines, demonstrating its specificity. Importantly, these peptides have no effect on fibroblast growth factor receptor signaling. Collectively these data provide novel mechanistic insights into phosphorylation dependent cross-talk between integrin and VEGFR2.
Arthroscopic Subacromial Decompression for Small and Medium Size Tears of Rotator Cuff without Tendon Repair  [PDF]
Suhail Karkabi, Nahum Rosenberg
Open Journal of Clinical Diagnostics (OJCD) , 2014, DOI: 10.4236/ojcd.2014.44034
Abstract: According to our previous clinical impression, we hypothesized that patients who had symptomatic rotator cuff tendon tear in a diamemter below 3 cm would benefit from arthroscopic subacromial decompression only, without the need for the repair of the thorn tendon. From 1998 to 2003, 160 patients (168 shoulders) had arthroscopic subacromial decompression for impingement syndrome with a torn rotator cuff without repairing the tear of the cuffs (120 males and 40 females). The average patient age was 64 years and the average follow up was 30 months. At follow up, 96 patients (60%) had full recovery; 55 patients (35%) had residual low grade shoulder pain on effort and 7 patients (5%) had poor outcome. In the last group of patients with unsatisfactory outcome, the postoperative Constant score was only 64 points. In 95% of patients, the average Constant score values raised from average preoperative value of 62 to postoperative average score of 82. According to these results, there is an indication that in patients in the seventh decade of life or older with symptomatic rotator cuff tear, pain relief and good shoulder function can be achieved by more conservative approach of subacromial decompression alone, providing a clear diagnosis that the diameter of the tear in the supraspinatus and infraspinatus tendons is below 3 cm.
Arthroscopic Debridement with Lavage and Arthroscopic Lavage Only as the Treatment of Symptomatic Osteoarthritic Knee  [PDF]
Suhail Karkabi, Nahum Rosenberg
Open Journal of Clinical Diagnostics (OJCD) , 2015, DOI: 10.4236/ojcd.2015.52013
Abstract: In this prospective follow up study we evaluated and compared the effect of arthroscopic lavage with and without debridement as a treatment of moderately osteoarthritic knees in middle aged and elderly population. The study group comprised of 500 patients (250 patients for each type of treatment, mean age 58 years). The patients were followed six months, three years and six years postoperatively. Following both treatments there was a clear deterioration in function of the knee function over the time, as measured starting at six months follow up until six years postoperatively (p < 0.001). This deterioration was more prominent in patients after treatment by the arthroscopic lavage only. We show that for the patients with high functional demand and expectations for long term rehabilitation and improvement both arthroscopic treatments are not satisfactory in more of 60% of cases.
Open software in small enterprises. Private medical practise example
Dominik Meller
Contemporary Economy , 2011,
Abstract: Article covers basic concepts of free and open software and its implementation at small health care facilities. It summarizes costs of possession and maintenance free/open and proprietary software. Functional analysis is conducted on example of office software. Further analysis covers barriers of open software implementation based on requirements of small health care facilities. Finally, according to stated requirements suggestion of ways to overcome these barriers are made.
Equipment review: Tracheal gas insufflation
Avi Nahum
Critical Care , 1998, DOI: 10.1186/cc124
Abstract: Carbon dioxide elimination during TGI depends on catheter flow rate because fresh gas flushes a greater portion of the proximal deadspace at higher flow rates. Moreover, at higher flow rates, turbulence generated at the catheter tip may further enhance distal gas mixing. The volume of fresh gas introduced into the trachea during TGI depends on expiratory time (TE) and catheter flow rate (Vc). At a certain TE × Vc, fresh gas completely sweeps the proximal anatomic deadspace during expiration. At that point, increasing Vc most likely does not dilute the CO2 residing in the series deadspace any further. This operational charactertistic of TGI, and the fact that the decrease in the partial pressure of CO2 (PaCO2) caused by a reduction in total physiologic deadspace fraction (VD/VT) is much less at lower VD/VT, limits the decrement in PaCO2 afforded by TGI at high Vc [8]. Nevertheless, at high Vc (< 10–15 1/min) PaCO2 continues to decrease with increasing Vc, but at a slower rate [8,9,10]. Once the series deadspace is flushed completely by the fresh gas during expiration, the flow dependence of PaCO2 is thought to be secondary to enhanced turbulent mixing in the airways distal to the catheter tip [5,11,12]. TGI is unlikely to be very effective when the alveolar as opposed to the series compartment dominates the total physiologic deadspace; yet, at small tidal volumes (whenever series deadspace is especially high) or when alveolar ventilation is very low. TGI should be a helpful adjunct to conventional mechanical ventilation (CMV) [8].During TGI, more distal catheter placement improves CO2 elimination as TGI can flush a greater portion of the deadspace proximal to the catheter tip during exhalation [5,7]. Advancing the catheter also moves the turbulence zone generated by the catheter closer to the periphery, thereby improving the efficacy of TGI. However, for most clinical applications, TGI efficiency is optimized when the catheter tip is positioned within a few centimete
Les juifs à Smyrne : de l’enfermement à l’ouverture vers le monde Jews in Smyrna : from Confinement to Awakening.
Henri Nahum
Revue des Mondes Musulmans et de la Méditerranée , 2012, DOI: 10.4000/remmm.2799
Abstract: Constituée plus tard que celles des autres cités de l'Empire ottoman, la communauté juive de Smyrne conna t une période de prospérité au xviie siècle, co ncidant avec le développement économique de la ville. D'abord installé près de la c te, le quartier juif se situe ensuite au centre de la cité, près du Konak ; au xixe siècle, il a un aspect misérable ; les habitants n'en sortent guère. Vers 1900, les juifs de Smyrne participent à nouveau à l'expansion économique du grand port égéen et sortent de leur isolement. L'incendie de septembre 1922, qui met fin à la guerre gréco-turque, bouleverse l'équilibre urbain. La transformation de l'état plurinational ottoman en un état-nation turc, les maladresses du gouvernement républicain, l'instauration d'un imp t frappant préférentiellement les non musulmans, la création de l'état d'Isra l, provoquent une émigration massive des juifs de Smyrne. Ils sont aujourd'hui moins de 2 000. Set up later than those of the other cities of the Ottoman Empire, the Jewish community of Smyrna enjoyed a time of prosperity in the 17th century connected to the expanding commercial activity of the city. First located by the seaside, the Jewish quarter moved later to the center of the city, near the Konak. In the 19th century, it looked shabby; its inhabitants seldom went out of it. About 1900, the Jews of Smyrna take part in the economical expansion of the great Aegean port and give up their isolation. The fire of September 1922 which puts an end to the Greek-Turkish war changes drastically the equilibrium of the city. The transformation of the plurinational Ottoman Empire into a Turkish nation-state, the awkwardness of the republican government, a capital levy on non-Muslim citizens, the creation of the State of Israel, empty the city of its Jewish inhabitants. Today, their number is less than 2 000.
AGN Outflows: Analysis of the Absorption Troughs
Nahum Arav
Physics , 2002,
Abstract: With the advent of Chandra and XMM, X-ray lines spectroscopy of AGN outflows is off to an exciting start. In this paper we illuminate some of the complications involved in extracting the outflow's physical conditions (ionization equilibrium, total column density, chemical abundances) from such spectroscopic data. To do so we use the example provided by high-quality FUSE and HST observations of the outflow seen in NGC 985. We show how simple determinations of the column density in the UV absorption lines often severely underestimate the real column densities. This is due to strong non-black saturation of the absorption troughs, where in many cases the UV line profile mainly reflects the velocity-dependent covering factor rather than the column density distribution. We then show that underestimating individual ionic column densities by a factor of 5 can cause a two orders of magnitude error in the inferred total column density of the outflow. In some case this will be enough to associate the UV and X-ray absorber with the same outflowing material. Finally, we note that the UV spectra of NGC 985 have 10--20 times the resolution and 2--5$\times$ the S/N per resolution element compared with the best available Chandra spectra of similar objects. Therefore, in the X-ray band non-black saturation and velocity-dependent covering factor effects will only become abundantly clear using vastly more capable future X-ray telescopes. However, by taking into consideration the lessons learned from the UV band, we can greatly improve the quality of physical constraints we extract from current X-ray data of AGN outflows.
PG 0946+301: the Rosetta Stone of BALQSOs?
Nahum Arav
Physics , 1998,
Abstract: We describe the motivation and features of a multiwavelength spectroscopic campaign on broad absorption line (BAL) QSO PG~0946+301. The main goal of this project is to determine the ionization equilibrium and abundances (IEA) in BAL outflows. Previous studies of IEA in BALQSOs were based on the assumption that the BALs are not saturated so that the column densities inferred from the apparent optical depths are realistic. This critical assumption is at odds with several recent observations and with analysis of existing data which indicate that the absorption troughs are heavily saturated even when they are not black. In addition, X-ray observations, which are important for constraining the ionizing continuum, were not available for those objects that had UV spectral data. Quantifying the level of saturation in the BALs necessitates UV spectroscopy with much higher S/N and broader spectral coverage than currently exist. After taking into account the capabilities of available observatories, our best hope for a substantial improvement in understanding the IEA in BALQSOs is to concentrate considerable observational resources on the most promising object. Our studies of available HST and ground-based spectra show that PG~0946+301 is by far the best candidate for such a program. This BALQSO is at least five times brighter, shortward of 1000 A rest frame, than any other object, and due to its low redshift it has an especially sparse Lya forest. At the same time PG~0946+301 is a typical BALQSO and therefore its IEA should be representative. To this effect we are developing a multiwavelength spectroscopic campaign (UV, FUV, X-ray and optical) on BALQSO PG 0946+301. We discuss the goals and feasibility of each observational component: HST, FUSE, ASCA and ground-based.
Fubctional integral approach to quantum gauge theories on a noncommutative space-time
Nahum Zobin
Physics , 2006,
Abstract: We propose a construction of actions of a quantum gauge field theory on a noncommutative space-time, based on a Fourier transform on the Doplicher-Fredenhagen-Roberts group. This approach leads to a functional integral representation of the action, which in turn leads to considering the space of probability measures on the classical space-time as a noncommutative version of the space-time. This approach allows a very natural treatment of gauge fields terms in the action.
The Generic Critical Behaviour for 2D Polymer Collapse
Adam Nahum
Physics , 2015,
Abstract: The nature of the theta point for a polymer in two dimensions has long been debated, with a variety of candidates put forward for the critical exponents. This includes those derived by Duplantier and Saleur (DS) for an exactly solvable model. We use a representation of the problem via the $CP^{N-1}$ sigma model in the limit $N \rightarrow 1$ to determine the stability of this critical point. First we prove that the DS critical exponents are robust, so long as the polymer does not cross itself: they can arise in a generic lattice model, and do not require fine tuning. This resolves a longstanding theoretical question. However there is an apparent paradox: two different lattice models, apparently both in the DS universality class, show different numbers of relevant perturbations, apparently leading to contradictory conclusions about the stability of the DS exponents. We explain this in terms of subtle differences between the two models, one of which is fine-tuned (and not strictly in the DS universality class). Next, we allow the polymer to cross itself, as appropriate e.g. to the quasi-2D case. This introduces an additional independent relevant perturbation, so we do not expect the DS exponents to apply. The exponents in the case with crossings will be those of the generic tricritical $O(n)$ model at $n=0$, and different to the case without crossings. We also discuss interesting features of the operator content of the $CP^{N-1}$ model. Simple geometrical arguments show that two operators in this field theory, with very different symmetry properties, have the same scaling dimension for any value of $N$ (equivalently, any value of the loop fugacity). Also we argue that for any value of $N$ the $CP^{N-1}$ model has a marginal parity-odd operator which is related to the loops' winding angle.
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