Placental MRI: Development of an MRI compatible ex vivo system for whole placenta dual perfusion.

PURPOSE: Placental dysfunction plays a key role in diseases that affect the fetus in utero and after birth. Aiming to develop a platform for validating in vivo placental MRI and investigations into placental physiology, we designed and built a prototype MRI-compatible perfusion chamber with an integrated MRI receive coil for high SNR ex vivo placental imaging. PRINCIPAL RESULTS: After optimizing placenta vascular clearing and perfusion protocols, we performed contrast enhanced MR angiography and MR relaxometry on eight carefully selected placentas while they were perfused via the umbilical arteries (UAs). Additionally, two of these placentas underwent maternal perfusion via the intervillous space (IVS). Despite striving for homogenous perfusion across the whole placenta, imaging results were highly heterogeneous for both UA and IVS perfused placentas. By histology, we observed blood congestion in the villi in regions that showed low UA perfusion during MRI. In two placentas prominent chorionic arteries followed by adjacent veins underwent contrast enhancement in the absence of villous capillary blush. The single placenta from a pregnancy affected by IUGR had the most homogeneous villous capillary perfusion. MAJOR CONCLUSIONS: A dual perfusion system for ex vivo placentas compatible with MRI permitted assessment of UA and IVS placental perfusion. We observed spatial UA perfusion heterogeneity and evidence for arteriovenous shunting in placentas from normal pregnancies and deliveries, but relative villous capillary perfusion homogeneity in a single IUGR placenta. Future work will focus on system optimization, followed by physiological manipulation and validation of in vivo placental MRI.

Improvement of size-based particle separation throughput in slanted spiral microchannel by modifying outlet geometry.

The inertial microfluidic technique, as a powerful new tool for accurate cell/particle separation based on the hydrodynamic phenomenon, has drawn considerable interest in recent years. Despite numerous microfluidic techniques of particle separation, there are few articles in the literature on separation techniques addressing external outlet geometry to increase the throughput efficiency and purity. In this work, we report on a spiral inertial microfluidic device with high efficiency (>98%). Herein, we demonstrate how changing the outlet geometry can improve the particle separation throughput. We present a complete separation of 4 and 6 µm from 10 µm particles potentially applicable to separate microalgae (Tetraselmis suecica from Phaeodactylum tricornutum). Two spiral microchannels with the same cross section dimension but different outlet geometry were considered and tested to investigate the particle focusing behavior and separation efficiency. As compared with particle focusing observed in channels with a simple outlet, the particle focusing in a modified outlet geometry appears in a more successful focusing manner with complete separation. This simple approach of particle separation makes it attractive for lab-on-a-chip devices for continuous extraction and filtration of a wide range of cell/particle sizes.

Phase transitions and asymmetry between signal comprehension and production in biological communication.

We introduce a model for collective information acquisition from the environment, in a biological population. In this model, individuals can make noisy observations of the environment, and communicate their observation by production and comprehension of signals. As the communication noise decreases, the model shows an order-disorder transition from a disordered phase in which no consensus about the environmental state exists to an ordered phase where the population forms a consensus about the environmental state. The ordered phase itself is composed of an informed consensus, in which the correct belief about the environment prevails, and an uninformed consensus phase, in which consensus on a random belief about the environmental state is formed. The probability of reaching informed consensus increases with increasing the observation probability. This phenomenology implies that a maximum noise level, and a minimum observation probability are necessary for informed consensus in a communicating population. Furthermore, we show that the fraction of observant individuals needed for the group to reach informed consensus decreases with increasing population size. This results from a shift in the uninformed-informed transition to smaller observation probabilities by increasing population size. Importantly, we also find that an amount of noise in signal production deteriorates the information flow and the inference capability, more than the same amount of noise in comprehension. This finding implies that there is higher selection pressure to reduce noise in production of signals compared to comprehension. Regarding this asymmetry, we propose an experimental design to separately measure comprehension and production noise in a given population and test the predicted asymmetry.

Predisposing factors for seroma formation in patients undergoing thyroidectomy: Cross-sectional study.

INTRODUCTION: Seroma is defined as collection of fluid within the surgical site during postoperative period that causes several complications. Recognition of predisposing risk factors can lead to avoid seroma formation after thyroidectomy. MATERIALS AND METHODS: A cross-sectional study was carried out during a 3-year period and 678 patients were enrolled the study. We recorded demographic data, past medical history and the type of thyroidectomy were for all patients. We measured total and ionized serum calcium and albumin level in all patients before surgery and a day after it. All patients underwent total or subtotal thyroidectomy and if needed central neck dissection was performed subsequently. Patients underwent serial aspiration If they had seroma formation. RESULTS: The overall post-thyroidectomy seroma incidence was 2.2%. There was no statistically significant correlation while evaluating gender, age and body mass index with post-operative seroma formation. However, seroma formation was significantly higher in patients underwent total thyroidectomy (P = 0.041). The results of postoperative laboratory tests showed a significant lower level of ionized calcium in patients with seroma formation (P < 0.0001). Logistic regression showed statistically significant value for variables including age, BMI and decreased ionized calcium level, in developing of seroma. CONCLUSION: We showed that Seroma formation was lower during thyroidectomy via electrical vessel sealing system in comparison with previous studies. In our study, older age, greater body mass index and decreased ionized calcium level were predictors of seroma formation.

Double blind study of sertaconazole 2% cream vs. clotrimazole 1% cream in treatment of seborrheic dermatitis.

Treatment of seborrheic dermatitis (SD) is an important issue in dermatology. This study was undertaken to compare efficiency of sertaconazole 2% cream vs. clotrimazole 1% cream for the treatment of seborrheic dermatitis. One hundred twenty eight patients suffering from SD were studied. Patients were randomly divided into two groups. Sixty four patients received local sertoconazole 2% cream and in control group 64 patients received clotrimazole 1% cream. They were recommended to use the cream twice a day for 4 weeks. At the beginning of referring and 2 and 4 weeks after first visit, the patients were examined by a dermatologist to assess improvement of clinical symptoms. The mean age of sertaconazole and clotrimazole group patients was 34.78+/-13.54 and 38.68+/-11.88, respectively. The highest level of satisfaction (87.6%) was observed 28 days after sertaconazole administration and in clotrimazole group it was 50%. Relapse of the disease one month after stopping treatment was not observed in groups treated with sertaconazole 2% cream and clotrimazole 1% cream. This study suggests that sertaconazole 2% cream is an effective and well-tolerated treatment for moderate to severe facial seborrheic dermatitis.

Comparison of titanium elastic nails with traction and spica cast in treatment of children's femoral shaft fractures.

Titanium Elastic Nails (TEN) are commonly used to stabilize femoral fractures in school-aged children, but there have been few studies assessing the risk of traditional traction and application of spica cast. The aim of this study was to compare of titanium elastic nails with traction and spica cast in treatment of children's femoral shaft fractures. A group of thirty children aged 6-12 years with one-sided femoral shaft fracture were randomly allocated either to traction with spica casting group or titanium elastic nails group and were followed up to 1 year. Factors such as age, sex, time needed for walking with aids, time needed for independent walking, time needed for callus formation, time absent from school, time spent in hospital, malunion, malalignment and wound complication were recorded and compared. Fifteen patients (10 boys, 5 girls) with a mean age of 8.33 +/- 1.63 years were treated by traction and spica casting. The other 15 (9 boys, 6 girls) with a mean age of 8.73 +/- 1.53 years underwent surgery using TEN. Mean absence time from school, length of hospital stay, time needed for walking with and without help and angular deviation (varus or valgus) were significantly lower in the group treated by TEN (p-value < 0.05). Time needed for callus formation was significantly lower in spica casting group (p-value < 0.001). No statistically significant difference was observed between the two groups regarding malunion wound complications and hospital charges. The results indicated that a child in whom a femoral fracture is treated with TEN achieves recovery milestones significantly faster than a child treated with traction and spica cast.

Efficacy of reverse triangle screw fixation in patients suffering from femoral neck fractures.

Although the fractures of femoral neck are not so common, their accompanying complications are more frequent and important. This research aims at studying the results of reverse triangle screw fixation in patients suffering from femoral neck fractures in two groups with perfect and imperfect position of the mentioned screw. In a cohort study, 51 patients with femoral neck fracture appointed for the so-called reverse triangle screw fixation were divided into two perfect and imperfect groups considering surgeon comment on position of the screws. The patients were followed up for 12 months and the resulted outcomes were compared. There were 34 patients in the perfect group with mean age of 48.7 +/- 18.6 (18-80) and 17 patients in the imperfect group with mean age of 50.4 +/- 15.9 (19-80) years old. Both groups were the same considering underlying causes and fraction grades. The overall frequency of nonunion and avascular necrosis was 7.8 and 3.9%, respectively. These rates were 2.9 and 0% in the perfect group and 17.6 and 12.5% in the imperfect group, respectively (p > 0.05). The mean Harris hip score and motion range of the hip at different directions in the perfect group were substantially higher than those of the imperfect one. According to present results, position of the screws determined by the surgeon after operating the reverse triangle screw fixation in femoral neck fractures may significantly affect the prognosis of patients.

Excision of osteoid osteoma with intramedullary reaming: a new method.

Osteoid osteoma is a small benign bone tumor usually affects adolescents and young adults. Although this tumor mainly affects the shafts of long bones there have been several reports of subperiosteal and intramedullary involvement .Complete surgical excision is the classic treatment of choice for patients with osteoid osteoma. Despite the small size of the tumor, the operative procedure for its removal can be extensive .The surgeon may have to excise a significant piece of bone to be sure the lesion is removed. There is a risk of fracture if a large amount of bone is removed and therefore internal fixation, bone grafting, or both may be required. In recent years several techniques of minimally invasive treatment of osteoid osteoma have been proposed. We introduce intramedullary reaming as a minimally invasive procedure for the treatment of intramedullary osteoid osteoma in long bones.

Simulation of DNA electrophoresis through microstructures.

The dependence of the mobility of DNA molecules through an hexagonal array of micropillars on their length and the applied electric field was investigated and it was found that mobility is a nonmonotonic function of their length. Results also revealed that the size dependence of the DNA mobility depends on the applied electric field and there is a crossover around E approximately 25 V/cm for the mobility of lambda-DNA and T4-DNA. These observations are explained in terms of the diffusion process inside the structure affected by the solvent and are modeled using the Langevin and its corresponding Fokker-Planck equations. The phenomenon is generalized under three regimes in a phase diagram relating the electric field and the DNA lengths. The model and the associated phase diagram described here provide an explanation for the conflicting results reported by previous authors (Han et al. on the one hand, and Duong et al. and Inatomi et al. on the other) about the dependence of mobility on the DNA size in lattices near or below the radius of gyration.

New attractor states for synchronous activity in synfire chains with excitatory and inhibitory coupling.

In a feedforward network of integrate-and-fire neurons, where the firing of each layer is synchronous (synfire chain), the final firing state of the network converges to two attractor states: either a full activation or complete fading of the tailing layers. In this article, we analyze various modes of pattern propagation in a synfire chain with random connection weights and delta-type postsynaptic currents. We predict analytically that when the input is fully synchronized and the network is noise free, varying the characteristics of the weights distribution would result in modes of behavior that are different from those described in the literature. These are convergence to fixed points, limit cycles, multiple periodic, and possibly chaotic dynamics. We checked our analytic results by computer simulation of the network, and showed that the above results can be generalized when the input is asynchronous and neurons are spontaneously active at low rates.