Numerical simulation of the fluid dynamics in vitreous cavity due to saccadic eye movement

In this study, the flow dynamics of vitreous due to saccadic movements following vitreous liquefaction or in post-vitrectomy eyes is investigated. Using a dynamic mesh technique, the eye motion was modeled and unsteady three-dimensional forms of continuity and Navier-Stokes equations were solved numerically. Firstly, the numerical model was validated for a sphere as a model of vitreous chamber and agrees well with the results based on available analytic solutions and experimental data. Then, numerical simulation was performed based on a deformed sphere with an indentation representing the lens. This consists of a vitreous cavity filled with a liquid having the viscosity of liquefied vitreous and balanced salt solution. The wall shear stress on the retina was computed and compared for various saccade amplitudes. Also, the effect of variation in vitreous viscosity and the size of lens indentation are investigated. The results show that the secondary flow in the vertical direction in the vitreous cavity is much higher for the liquefied vitreous and balanced salt solution compared with that for silicone oil. The possible effect of shear stress on the retinal detachment for all studied cases is discussed. A semi-analytic correlation is also developed for maximum wall shear stress of the spherical domain that is subjected to sinusoidal rotations.     

A fatal case of Degos' disease which presented with recurrent intestinal perforation

Degos’ disease,otherwise known as "malignant atrophic papulosis" is a rare vasculopathy with an unknown etiology characterized by typical cutaneous lesions.Involvement of the gastrointestinal(GI) tract is observed in approximately half of patients and small infarctions in the mucosa can cause perforation and resulting peritonitis,the leading cause of death.We present a fatal case of Degos’ disease with skin and GI involvement,manifesting as recurrent intestinal perforations and peritonitis,in a 15-year-old Iranian boy.     

Midterm outcomes and quality of life following percutaneous coronary intervention in nonagenarians

The midterm clinical and functional benefits of percutaneous coronary intervention in patients aged ≥90 years have not been clearly defined. From January 2005 to June 2009, 173 patients aged ≥90 years underwent diagnostic cardiac catheterization, of whom 90 underwent percutaneous coronary intervention. There were 45 men (50%) and 45 women (50%), with a mean age of 92 years (range 90 to 101). Of these, 24 patients (27%) presented with ST-segment elevation myocardial infarction, 31 (34%) with non-ST-segment elevation myocardial infarction, 28 (31%) with unstable angina pectoris, and 2 (2%) with stable angina pectoris; 5 patients (6%) were studied for preoperative risk assessment. A total of 127 lesions were successfully treated using 102 drug-eluting stents and 37 bare-metal stents, with a mean of 1.5 stents per patient. Postprocedural complications included renal insufficiency in 5 patients (5.6%), heart failure in 6 patients (6.7%), and cardiogenic shock in 2 patients (2.2%). Seventy-seven patients (85.6%) experienced no postprocedural complications. In-hospital mortality was 7.8%, and actuarial survival was 61.5 ± 5.2% at 24 months and 31.6 ± 6.1% at 48 months. The SF-36 Health Survey was administered at follow-up, and results demonstrated a quality of life similar to that of the general population corrected for age and gender. In conclusion, this study demonstrates that percutaneous coronary intervention in nonagenarians can be accomplished with low mortality and morbidity and excellent midterm results. Moreover, functional improvement in nonagenarians supports enhanced quality of life comparable to that of the general population.     

Placement of intraventricular catheters using flexible electromagnetic navigation and a dynamic reference frame: a new technique

BACKGROUND: Catheterization of narrow ventricles may prove difficult resulting in misplacement or inefficient trials with potential damage to brain tissue. MATERIAL AND METHODS: The application of a new module for navigated ventricular catheterization using flexible electromagnetic navigation and a dynamic reference frame is presented. RESULTS: Navigated catheter placement was successful and accurate in a pilot study. Electromagnetic interferences had to be taken into consideration. CONCLUSION: Flexible electromagnetic navigation with a dynamic reference frame is a useful tool for catheter placement as it reduces the risk of misplacement or repeated catheterization trials.     

Anticonvulsant effect of celecoxib on pentylenetetrazole-induced convulsion: Modulation by NO pathway

This study aimed to examine whether celecoxib influences clonic seizure thresholds through modulation of nitric oxidergic (NO) pathway. The effect of celecoxib (1-5 mg per kg, p.o.) was investigated on clonic seizures induced by pentylenetetrazole (PTZ, 50 and 80 mg per kg, i.p.) in male Swiss mice. The interaction of celecoxib-induced effects with NO pathway was examined using a NO synthase (NOS) inhibitor, N(G)-omega-nitro-L-arginine methyl ester (L-NAME, 20 and 50 mg per kg, i.p.) and a NOS substrate, L-arginine (100 and 200 mg per kg, i.p.). The criteria for the development of seizure activity were the possibility for appearance of generalized clonus and prolongation of latency to the onset of convulsions following administration of 50 and 80 mg per kg of PTZ, respectively. Pretreatment with celecoxib (2.5 and 5 mg per kg) or L-NAME (50 mg per kg) induced anticonvulsant effect on the PTZ-induced clonic seizures. L-arginine at the dose of 200 mg per kg had proconvulsant effect. A sub-effective dose of celecoxib (1 mg per kg) induced an additive anticonvulsant effect when co-administered with L-NAME (20 mg per kg). Although L-arginine (100 mg per kg) per se did not influence PTZ-induced convulsion, it could attenuate the anticonvulsant effect of celecoxib (5 mg per kg). Our results indicate that celecoxib induces an anticonvulsant effect on clonic seizure threshold that may involve NO pathway.     

Engineered antibody Fc variants with enhanced effector function

Antibody-dependent cell-mediated cytotoxicity, a key effector function for the clinical efficacy of monoclonal antibodies, is mediated primarily through a set of closely related Fcgamma receptors with both activating and inhibitory activities. By using computational design algorithms and high-throughput screening, we have engineered a series of Fc variants with optimized Fcgamma receptor affinity and specificity. The designed variants display >2 orders of magnitude enhancement of in vitro effector function, enable efficacy against cells expressing low levels of target antigen, and result in increased cytotoxicity in an in vivo preclinical model. Our engineered Fc regions offer a means for improving the next generation of therapeutic antibodies and have the potential to broaden the diversity of antigens that can be targeted for antibody-based tumor therapy.