53 research outputs found
Association between Brain-Derived Neurotrophic Factor (BDNF) Levels in 2nd Trimester Amniotic Fluid and Fetal Development.
The development of the fetal nervous system mirrors general fetal development, comprising a combination of genetic resources and effects of the intrauterine environment. Our aim was to assess the 2nd trimester amniotic fluid levels of brain-derived neurotrophic factor (BDNF) and to investigate its association with fetal growth. In accordance with our study design, samples of amniotic fluid were collected from women who had undergone amniocentesis early in the 2nd trimester. All pregnancies were followed up until delivery and fetal growth patterns and birth weights were recorded, following which pregnancies were divided into three groups based on fetal weight: (1) AGA (appropriate for gestational age), (2) SGA (small for gestational age), and (3) LGA (large for gestational age). We focused on these three groups representing a reflection of the intrauterine growth spectrum. Our results revealed the presence of notably higher BDNF levels in the amniotic fluid of impaired growth fetuses by comparison with those of normal growth. Both SGA and macrosomic fetuses are characterized by notably higher amniotic fluid levels of BDNF (mean values of 36,300 pg/ml and 35,700 pg/ml, respectively) compared to normal-growth fetuses (mean value of 32,700 pg/ml). Though apparently small, this difference is, nevertheless, statistically significant (p value < 0.05) in SGA fetuses in the extremes of the distribution, i.e., below the 3rd centile. In conclusion, there is clear evidence that severe impairment of fetal growth induces the increased production of fetal brain growth factor as an adaptive mechanism in reaction to a hostile intrauterine environment, thereby accelerating fetal brain development and maturation
Resource Competition on Integral Polymatroids
We study competitive resource allocation problems in which players distribute
their demands integrally on a set of resources subject to player-specific
submodular capacity constraints. Each player has to pay for each unit of demand
a cost that is a nondecreasing and convex function of the total allocation of
that resource. This general model of resource allocation generalizes both
singleton congestion games with integer-splittable demands and matroid
congestion games with player-specific costs. As our main result, we show that
in such general resource allocation problems a pure Nash equilibrium is
guaranteed to exist by giving a pseudo-polynomial algorithm computing a pure
Nash equilibrium.Comment: 17 page
Mixed-precision deep learning based on computational memory
Deep neural networks (DNNs) have revolutionized the field of artificial
intelligence and have achieved unprecedented success in cognitive tasks such as
image and speech recognition. Training of large DNNs, however, is
computationally intensive and this has motivated the search for novel computing
architectures targeting this application. A computational memory unit with
nanoscale resistive memory devices organized in crossbar arrays could store the
synaptic weights in their conductance states and perform the expensive weighted
summations in place in a non-von Neumann manner. However, updating the
conductance states in a reliable manner during the weight update process is a
fundamental challenge that limits the training accuracy of such an
implementation. Here, we propose a mixed-precision architecture that combines a
computational memory unit performing the weighted summations and imprecise
conductance updates with a digital processing unit that accumulates the weight
updates in high precision. A combined hardware/software training experiment of
a multilayer perceptron based on the proposed architecture using a phase-change
memory (PCM) array achieves 97.73% test accuracy on the task of classifying
handwritten digits (based on the MNIST dataset), within 0.6% of the software
baseline. The architecture is further evaluated using accurate behavioral
models of PCM on a wide class of networks, namely convolutional neural
networks, long-short-term-memory networks, and generative-adversarial networks.
Accuracies comparable to those of floating-point implementations are achieved
without being constrained by the non-idealities associated with the PCM
devices. A system-level study demonstrates 173x improvement in energy
efficiency of the architecture when used for training a multilayer perceptron
compared with a dedicated fully digital 32-bit implementation
Intestinal Spirochaetosis: Light and Electron Microscopic Study
24 cases of colon spirochaetosis have been studied by light and electron microscopy. This condition, although rarely diagnosed because of the absence of special clinical symptoms, seems to be a rather frequent histologic finding with marked variation in its geographical incidence. In our material the incidence of spirochaetosis was 16.5%, almost double than in Great Britain. © 1987, Gustav Fischer Verlag · Stuttgart · New York. All rights reserved
A primary tumour of the oesophagus with both melanocytic and schwannian differentiation. Melanocytic schwannoma or malignant melanoma?
A 76 year old white woman presented with a four month history of dysphagia and weight loss. Clinical, radiological, and endoscopic examination revealed a pigmented mass in the lower third of the oesophagus. The preoperative diagnosis, including biopsy examination, was that of malignant melanoma. Following oesophageal resection, the mass was found to be a localised, relatively superficial tumour with light, electron microscopic, and immunohistochemical features common to both Schwann cells and melanocytes. The patient survived 46 months after surgery and died of a stroke, with no evidence of tumour recurrence. The tumour is presented as a case of melanocytic schwannoma, with unique features when compared with oesophageal melanotic schwannomas and malignant melanomas described in the literature. The differential diagnosis is discussed and an origin from a common precursor cell of neural crest origin is postulated
Evolution of Renal Function in Renal Allograft Recipients under Various Everolimus-Based Immunosuppressive Regimens
Background Long-term allograft survival is a major challenge in kidney transplantation. This study sought to estimate the evolution of renal function in patients receiving different immunosuppressive regimens based on everolimus (EVR). Methods Ninety-nine renal allograft recipients were included in a 12-month open-label, noninterventional, prospective, single-center study. Patients were divided into 2 groups, de novo and late conversion to EVR. Results Group A included 40 patients under calcineurin inhibitor (CNI) plus EVR. Median time posttransplantation was 33.06 months (interquartile range 18.25 to 42.85). Mean estimated glomerular filtration rate (eGFR) the first month posttransplantation (using Modification of Diet in Renal Disease formula) was 54.89 ± 19.08 mL/min, and mean proteinuria was 0.54 ± 0.38 g/24 h. At the end of follow up, mean eGFR and mean proteinuria significantly improved (65.49 ± 20.79 mL/min; P =.011 and 0.157 ± 0.089 g/24 h; P =.002, respectively). Group B consisted of 59 patients; 49 of them initially received mycophenolic acid (MPA) plus CNI, and 10 had been on azathioprine plus CNI. Initial immunosuppression was switched to MPA plus EVR in 49 patients, CNI plus EVR in 4 patients, and EVR in 6 patients, in a median time of 37 months (interquartile range 14.75 to 112.5) posttransplantation. Main indications for conversion were malignancies and biopsy-proven chronic allograft injury. Mean eGFR 1 month posttransplantation and at the time of conversion were 50.79 ± 17.83 mL/min and 57.39 ± 19.17 mL/min, respectively (P =.014). After conversion, mean eGFR increased (66 ± 24.89 mL/min; P =.006). Mean proteinuria was 0.509 ± 0.530 g/24 h the first posttransplantation month, and it remained stable at 0.415 ± 0.431 g/24 h until study completion. Two acute rejection episodes occurred. At the end of follow-up, patient and death-censored graft survival were 97% and 100%, respectively. Conclusions In kidney transplant recipients, EVR either de novo or after conversion with or without CNI is a safe and effective treatment that preserves renal function. © 2015 Elsevier Inc
Invasive diagnostic procedures and risk of hypertensive disorders in pregnancy
Objective To determine whether the risk of hypertensive complications differs among low-risk women who undergo prenatal diagnosis via chorionic villus sampling (CVS) and amniocentesis. Methods In a retrospective study, data were analyzed from women who underwent prenatal diagnosis by CVS or amniocentesis at Alexandra Maternity Hospital, Athens, Greece, between 1998 and 2011. All women had either transabdominal CVS at 10-13 weeks of pregnancy with a 20-gauge needle, or amniocentesis at 17-21 weeks with a 22-gauge needle, both under direct ultrasound guidance. Only women who had cytogenetically normal pregnancies and delivered at the study hospital were included. The main outcome measure was the development of hypertensive complications. Results Overall, 3243 women who underwent CVS and 6875 woman who underwent amniocentesis met the inclusion criteria, and their outcomes were analyzed. In total, 237 women (2.3%) developed hypertensive disorders during their pregnancy. The incidence of pre-eclampsia (2.4% vs 0.8%) and total hypertensive disorders (3.8% vs 1.7%) was significantly higher (P < 0.001) in the CVS group than in the amniocentesis group. Conclusion Women who underwent CVS had a significantly higher risk of developing hypertensive disorders in comparison to those who underwent amniocentesis. This finding warrants further investigation via a well-designed prospective randomized trial. © 2014 International Federation of Gynecology and Obstetrics
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