Factors that Influence Placement of Gastrostomy Tube in Infants with Complex Congenital Heart Disease: A Single Center Study

BACKGROUND

Factors that determine the need for Gastrostomy tube (G-tube) placement in infants with complex congenital heart defects (CHD) are variable. We aim to identify factors that improve counseling of expectant parents regarding postnatal outcomes and management.

METHODS

We performed a retrospective review of medical record of infants with prenatal diagnoses of complex CHD between 2015-2019 in a single tertiary care center and assessed risk factors for G-tube placement with linear regression.

RESULTS

Of the 105 eligible infants with complex CHD, 44 infants required G-tube (42% ). No significant association was observed between G-tube placement and chromosomal abnormalities, cardiopulmonary bypass time or type of CHD. Median days on noninvasive ventilation (4 [IQR 2-12] vs. 3 [IQR 1-8], p = 0.035), time at which gavage-tube feeds were started postoperatively (3 [IQR 2-8] vs. 2 [IQR 0-4], p = 0.0013), time to reach full-volume gavage-tube feeds (6 [IQR 3-14] vs. 5 [IQR 0-8], p = 0.038) and intensive care unit (ICU) length of stay (LOS) (41 [IQR: 21 - 90] vs. 18 [IQR: 7 - 23], p <  0.01) were associated with G-tube placement. Infants with ICU LOS duration longer than median had almost 7 times the odds of requiring a G-tube (OR: 7.23, 95% CI: 2.71-19.32; by regression).

CONCLUSIONS

Delay in initiation and in reaching full-volume gavage-tube feeds after cardiac surgery, increased number of days spent on non-invasive ventilation and in the ICU were found to be significant predictors for G-tube placement. The type of CHD and the need for cardiac surgery were not significant predictors for G-tube placement.

1008 Incidental Solitary Cystic Mediastinal Lymphangioma with Mass Effect Complications: A Case Report

Introduction

Cystic mediastinal lymphangiomas (CML) are exceedingly rare, representing &lt;1% of cystic lymphangiomas (CL), and typically present before 2 years of age. Few cases describe adult presentations of solitary CML and none describe symptomatic cases with ‘mass-effect’ complications. We describe an incidental finding of a symptomatic solitary CML causing mass effect complications and our definitive surgical management.

Case Report

A 44-year-old Caucasian male presented with reduced responsiveness due to mixed drug overdose of fluoxetine and ibuprofen. Plain chest radiograph (CXR) revealed incidental new mediastinal widening. Thoracic computed tomography (CT) showed a well-defined lesion (75x63mm) in the right paratracheal region, with associated compression of the superior vena cava, left brachiocephalic vein and displacement of the azygos vein. Further questioning revealed 6-months history of non-productive cough, worsening dyspnoea on exertion and chest pain radiating to the right of the chest. Complete surgical resection was performed via posterolateral thoracotomy. It was seen compressing the 2nd and 3rd intercostal nerves. Enlarged lymph nodes at station 4 and 10 were excised and sent for analysis with aspirate from the excised lesion. Pathological gross examination showed a multiloculated cystic lesion containing thin straw-coloured fluid. Microscopically, it was thin walled with smooth muscle and scattered clusters of lymphocytes; its lining was markedly attenuated comprising bland flat endothelial cells, positive for CD-31. Lymph node samples showed reactive changes.

Conclusions

Although CMLs are benign, their location and growth in the mediastinum can result in compression of surrounding structures. Early detection and complete surgical resection are paramount to prevent such complications and lesion recurrence.

Decreased Sestrin levels in patients with type 2 diabetes and dyslipidemia and their association with the severity of atherogenic index

PURPOSE

We earlier reported that Sestrin2 regulates monocyte activation and atherogenic events through AMPK-mTOR nexus under high-glucose and dyslipidemic conditions. However, the statuses of Sestrins in diabetes and dyslipidemia are not known. We report here on the status of Sestrins and their association with diabetic dyslipidemia and atherosclerosis.

METHODS

Individuals with normal glucose tolerance (NGT) (n = 46), dyslipidemia (n = 42), and patients with Type 2 diabetes with (n = 41) and without dyslipidemia (n = 40) were recruited from a tertiary diabetes centre, Chennai, India to study the mRNA expression levels of Sestrins (1, 2, and 3) in monocytes by RT-qPCR. Serum levels of Sestrins were measured using ELISA. Atherogenic index of plasma was calculated as log (triglyceride/HDL).

RESULTS

mRNA expressions of Sestrin1 and Sestrin3 were significantly reduced in monocytes under dyslipidemic conditions but not in diabetes condition. Interestingly, Sestrin2 mRNA expression was significantly reduced in all disease conditions including dyslipidemia, and diabetes with and without dyslipidemia. Sestrin2 mRNA levels were negatively correlated with glycemic and lipid parameters and plasma atherogenic index. Furthermore, circulatory Sestrin2 was also found to be significantly decreased in dyslipidemia (415.2 ± 44.7 pg/ml), diabetes (375 ± 45 pg/ml), and diabetes with dyslipidemia (319.2 ± 26.3 pg/ml) compared to NGT (706.3 ± 77 pg/ml) and negatively correlated with glycemic, lipid parameters, and plasma atherogenic index.

CONCLUSION

We report for the first time that Sestrins levels are significantly decreased in diabetes and dyslipidemic conditions. More strikingly, Sestrin2 had a strong association with atherogenic risk factors and severity of atherogenic index and we suggest that Sestrin2 may be used as a biomarker for assessing atherogenesis.

Impact of early postnatal exposure of red blood cell transfusions on the severity of retinopathy of prematurity

BACKGROUND

Postnatal exposure to red blood cell transfusion (RBCT) in premature infants is an important risk factor for Retinopathy of Prematurity (ROP) progression. We hypothesized that higher number and earlier timing of RBCT are associated with worse ROP severity and result in laser treatment at an earlier postmenstrual age (PMA) in very low birth weight (≤1500 g, VLBW) infants.

METHODS

A retrospective medical record review of 631 VLBW infants over a 5-year period was performed. Demographic features and potential clinical risk factors including number of RBCT, ROP severity, and progression to laser treatment were collected to evaluate predictors of severe ROP. ANCOVA, pairwise post-hoc analyses, and multivariate regression were used to determine associations between frequency and timing of RBCT and ROP severity.

RESULTS

Of the 456 eligible infants, 61 developed severe ROP (13%). There was significant correlation between number of RBCTs and ROP severity, adjusted for gestational age and birthweight (Adjusted R2 = 0.53; p <  0.001). Compared to infants with No/Mild and Type 2 ROP, infants with Type 1 ROP received more RBCTs, with higher number of RBCTs per week during the first month of life (mean RBCT in ROP No/Mild 5.7±0.4 vs Type 2 16.3±1.8 vs Type 1 22.4±1.5, p = 0.042). Laser-treated infants received a higher number of RBCTs than non-treated infants (mean RBCT 22.3 vs. 6.5, p <  0.001) but no correlation was observed between number of RBCTs and PMA at time of laser treatment.

CONCLUSION

Higher number of RBCTs in early postnatal life of VLBW infants was associated with more severe ROP.

Automated trichome counting in soybean using advanced image-processing techniques

PREMISE

Trichomes are hair-like appendages extending from the plant epidermis. They serve many important biotic roles, including interference with herbivore movement. Characterizing the number, density, and distribution of trichomes can provide valuable insights on plant response to insect infestation and define the extent of plant defense capability. Automated trichome counting would speed up this research but poses several challenges, primarily because of the variability in coloration and the high occlusion of the trichomes.

METHODS AND RESULTS

We developed a simplified method for image processing for automated and semi-automated trichome counting. We illustrate this process using 30 leaves from 10 genotypes of soybean (Glycine max) differing in trichome abundance. We explored various heuristic image-processing methods including thresholding and graph-based algorithms to facilitate trichome counting. Of the two automated and two semi-automated methods for trichome counting tested and with the help of regression analysis, the semi-automated manually annotated trichome intersection curve method performed best, with an accuracy of close to 90% compared with the manually counted data.

CONCLUSIONS

We address trichome counting challenges including occlusion by combining image processing with human intervention to propose a semi-automated method for trichome quantification. This provides new opportunities for the rapid and automated identification and quantification of trichomes, which has applications in a wide variety of disciplines.

Rheological transition in simple shear of moderately dense assemblies of dry cohesive granules

The rheology of homogeneous cohesive granular assemblies under shear at moderate volume fractions is investigated using the discrete element method for both frictionless and frictional granules. A transition in rheology from inertial to quasistatic scaling is observed at volume fractions below the jamming point of noncohesive systems, which is a function of the granular temperature, energy dissipation, and cohesive potential. The transition is found to be the result of growing clusters, which eventually percolate the domain, and change the mode of momentum transport in the system. Differences in the behavior of the shear stress normalized by the pressure are observed when frictionless and frictional cases are compared. These differences are explained through contact anisotropy after percolation occurs. Both frictionless and frictional systems are found to be vulnerable to instabilities after full system percolation has occurred, where the former becomes thermodynamically unstable and the latter may form shear bands. Finally, implications for constitutive modeling are discussed.

Distributed Newton Methods for Deep Neural Networks

Deep learning involves a difficult nonconvex optimization problem with a large number of weights between any two adjacent layers of a deep structure. To handle large data sets or complicated networks, distributed training is needed, but the calculation of function, gradient, and Hessian is expensive. In particular, the communication and the synchronization cost may become a bottleneck. In this letter, we focus on situations where the model is distributedly stored and propose a novel distributed Newton method for training deep neural networks. By variable and feature-wise data partitions and some careful designs, we are able to explicitly use the Jacobian matrix for matrix-vector products in the Newton method. Some techniques are incorporated to reduce the running time as well as memory consumption. First, to reduce the communication cost, we propose a diagonalization method such that an approximate Newton direction can be obtained without communication between machines. Second, we consider subsampled Gauss-Newton matrices for reducing the running time as well as the communication cost. Third, to reduce the synchronization cost, we terminate the process of finding an approximate Newton direction even though some nodes have not finished their tasks. Details of some implementation issues in distributed environments are thoroughly investigated. Experiments demonstrate that the proposed method is effective for the distributed training of deep neural networks. Compared with stochastic gradient methods, it is more robust and may give better test accuracy.

Ecological risk assessment of trace metal accumulation in sediments of Veraval Harbor, Gujarat, Arabian Sea

In this study, different types of indices were used to assess the ecological risk of trace metal contamination in sediments on the basis of sediment quality guidelines at Veraval Fishery Harbor. Sediment samples were collected from three sectors in pre-, post-, and monsoon seasons in 2006. Trace metal concentrations were higher in the inner sector during post-monsoon, and it showed the highest statistical significance (p<0.01) among the stations. Pollution load index was higher than unity, indicating alternation by effluent discharge from industries. Enrichment factor and geo-accumulation index showed that Cd, Pb, and Zn were enriched in the northern part of the harbor and Pb had accumulated in the harbor sediment. The ecological risk assessment index revealed that Ni, Zn, and Pb were higher than the effect range median values, indicating their potential toxicity to the aquatic environment in the Veraval Harbor. Hence, the harbor is dominated by anthropogenic activities rather than natural process.

A Simple Label Switching Algorithm for Semisupervised Structural SVMs

In structured output learning, obtaining labeled data for real-world applications is usually costly, while unlabeled examples are available in abundance. Semisupervised structured classification deals with a small number of labeled examples and a large number of unlabeled structured data. In this work, we consider semisupervised structural support vector machines with domain constraints. The optimization problem, which in general is not convex, contains the loss terms associated with the labeled and unlabeled examples, along with the domain constraints. We propose a simple optimization approach that alternates between solving a supervised learning problem and a constraint matching problem. Solving the constraint matching problem is difficult for structured prediction, and we propose an efficient and effective label switching method to solve it. The alternating optimization is carried out within a deterministic annealing framework, which helps in effective constraint matching and avoiding poor local minima, which are not very useful. The algorithm is simple and easy to implement. Further, it is suitable for any structured output learning problem where exact inference is available. Experiments on benchmark sequence labeling data sets and a natural language parsing data set show that the proposed approach, though simple, achieves comparable generalization performance.

Atom scale characterization of the near apex region of an atomic force microscope tip

Three-dimensional atom probe tomography (APT) is successfully used to analyze the near-apex regions of an atomic force microscope (AFM) tip. Atom scale material structure and chemistry from APT analysis for standard silicon AFM tips and silicon AFM tips coated with a thin film of Cu is presented. Comparison of the thin film data with that observed using transmission electron microscopy indicates that APT can be reliably used to investigate the material structure and chemistry of the apex of an AFM tip at near atomic scales.

Extension of the neuroprotective time window for thiazolidinediones in ischemic stroke is dependent on time of reperfusion

Stroke is a leading cause of death and disability but has limited therapeutic options. Thiazolidinediones (TZDs), agonists for the nuclear receptor, peroxisome proliferator-activated receptor (PPAR)γ, reduce infarct volume and improve neurologic function following transient middle cerebral artery occlusion (MCAO) in rats. Translation of these findings into clinical therapy will require careful assessment of dosing paradigms and effective time windows for treatment. Understanding the mechanisms by which TZDs protect the brain provides insight into how time windows for neuroprotection might be extended. We find that two TZDs, pioglitazone and rosiglitazone, significantly reduce infarct volume at doses similar to those used clinically (1 mg/kg for pioglitazone and 0.1 mg/kg for rosiglitazone). We also find that pioglitazone reduces infarction volume in a transient, but not a permanent MCAO model suggesting that reperfusion plays an important role in TZD mediated neuroprotection. Since PPARγ agonists reduce inflammation and oxidative stress, both of which are exacerbated by reperfusion, we hypothesized that TZDs would be most effective if administered prior to reperfusion. We administered TZDs 3 h after MCAO and found that infarction volume and neurologic function are significantly improved in animals reperfused at 3 h and 15 min (after TZD treatment), but not in animals reperfused at 2 h (before TZD treatment) when assessed either 24 h or 3 weeks after MCAO. While TZDs reduce intercellular adhesion molecule (ICAM) expression to a similar extent regardless of the time of reperfusion, leukocyte entry into brain parenchyma is more dramatically reduced when reperfusion is delayed until after drug treatment. The finding that delaying reperfusion until after TZD treatment is beneficial despite a longer period of ischemia, is dramatic given the widely held view that duration of ischemia is the most important determinate of injury.

An alternative method to determining optical lever sensitivity in atomic force microscopy without tip-sample contact

Force studies using atomic force microscopy generally require knowledge of the cantilever spring constants and the optical lever sensitivity. The traditional method of evaluating the optical lever sensitivity by pressing the tip against a hard surface can damage the tip, especially sharp ones. Here a method is shown to calculate the sensitivity without having to bring the tip into contact. Instead a sharpened tungsten wire is used to cause a point contact directly onto the cantilever and cause cantilever bending. Using beam theory, the sensitivity thus found can be converted to the equivalent sensitivity that would be obtained using the tip location. A comparison is presented between sensitivity values obtained from the conventional tip contact method and those derived from the wire-based technique for a range of cantilevers in air. It was found that the difference between the calculated sensitivity from the wire-based technique and the sensitivity obtained conventionally was less than 12%. These measurements indicate the presented method offers a simple alternative approach to obtain optical lever sensitivity without compromising the tip shape.

Nanoscale friction switches: friction modulation of monomolecular assemblies using external electric fields

This paper presents experimental investigations to actively modulate the nanoscale friction properties of a self-assembled monolayer (SAM) assembly using an external electric field that drives conformational changes in the SAM. Such "friction switches" have widespread implications in interfacial energy control in micro/nanoscale devices. Friction response of a low-density mercaptocarboxylic acid SAM is evaluated using an atomic force microscope (AFM) in the presence of a DC bias applied between the sample and the AFM probe under a nitrogen (dry) environment. The low density allows reorientation of individual SAM molecules to accommodate the attractive force between the -COOH terminal group and a positively biased surface. This enables the surface to present a hydrophilic group or a hydrophobic backbone to the contacting AFM probe depending upon the direction of the field (bias). Synthesis and deposition of the low-density SAM (LD-SAM) is reported. Results from AFM experiments show an increased friction response (up to 300%) of the LD-SAM system in the presence of a positive bias compared to the friction response in the presence of a negative bias. The difference in the friction response is attributed to the change in the structural and crystalline order of the film in addition to the interfacial surface chemistry and composition presented upon application of the bias.

Validation-Based Sparse Gaussian Process Classifier Design

Gaussian processes (GPs) are promising Bayesian methods for classification and regression problems. Design of a GP classifier and making predictions using it is, however, computationally demanding, especially when the training set size is large. Sparse GP classifiers are known to overcome this limitation. In this letter, we propose and study a validation-based method for sparse GP classifier design. The proposed method uses a negative log predictive (NLP) loss measure, which is easy to compute for GP models. We use this measure for both basis vector selection and hyperparameter adaptation. The experimental results on several real-world benchmark data sets show better or comparable generalization performance over existing methods.

Visualization by atomic force microscopy and FISH of the 45S rDNA gaps in mitotic chromosomes of Lolium perenne

The mitotic chromosome structure of 45S rDNA site gaps in Lolium perenne was studied by atomic force microscope (AFM) combining with fluorescence in situ hybridization (FISH) analysis in the present study. FISH on the mitotic chromosomes showed that 45S rDNA gaps were completely broken or local despiralizations of the chromatid which had the appearance of one or a few thin DNA fiber threads. Topography imaging using AFM confirmed these observations. In addition, AFM imaging showed that the broken end of the chromosome fragment lacking the 45S rDNA was sharper, suggesting high condensation. In contrast, the broken ends containing the 45S rDNA or thin 45S rDNA fibers exhibited lower density and were uncompacted. Higher magnification visualization by AFM of the terminals of decondensed 45S rDNA chromatin indicated that both ends containing the 45S rDNA also exhibited lower density zones. The measured height of a decondensed 45S rDNA chromatin as obtained from the AFM image was about 55-65 nm, composed of just two 30-nm single fibers of chromatin. FISH in flow-sorted G2 interphase nuclei showed that 45S rDNA was highly decondensed in more than 90% of the G2/M nuclei. Our results suggested that a failure of the complex folding of the chromatin fibers occurred at 45S rDNA sites, resulting in gap formation or break.

Recombinant factor VIIa in a case of pontine hemorrhage

A 59-year-old lady presented with hypertensive hemorrhage involving the pons. Since she presented within 3 hours of onset of the stroke, recombinant factor VIIa was administered. From a state of altered sensorium there was a rapid recovery of consciousness followed by gradual improvement in limb weakness. Serial CT scans of the brain revealed no further expansion of the hematoma. The hematoma progressively resolved. Recombinant factor VIIa could be an attractive therapeutic option in treating hemorrhages at critical sites like brainstem where expansion of hematoma could be fatal.

Method to generate surfaces with desired roughness parameters

A surface engineering method based on the electrostatic deposition of microparticles and dry etching is described and shown to be able to independently tune both amplitude and spatial roughness parameters of the final surface. Statistical models were developed to connect process variables to the amplitude parameters (center line average and root-mean-square) and a spatial parameter (autocorrelation length) of the final surfaces. Process variables include particle coverage, which affects both amplitude and spatial roughness parameters, particle size, which affects only spatial parameters, and etch depth, which affects only amplitude parameters. Correlations between experimental data and model predictions are discussed.

Role of ultrasonography and MRI in the detection of wide intraductal component of invasive breast cancer—a prospective study

AIM

To compare the role of ultrasound (US) and magnetic resonance imaging (MRI) in the detection of extent and direction of intraductal components around invasive breast cancer in comparison with histopathological findings.

MATERIALS AND METHODS

In 60 invasive breast cancers (59 patients), US features of the intraductal components were classified as: (a) solid ductal dilatation radiating from the tumour, (b) the presence of a satellite lesion in the same segment without ductal dilatation, (c) ductal dilatation between the main tumour and the satellite lesion. The criteria for the detection of intraductal components by MRI were as follows: (a) strand-like enhancement on the margin of the main tumour, (b) satellite lesions around the main tumour, or (c) bridging enhancement between the main tumour and the satellite lesion. The direction of the intraductal components was classified as towards the nipple and towards the periphery.

RESULTS

Wide intraductal components (>or=15 mm) towards the nipple were proven histopathologically in 17 of 59 (28.8%) cancers, and wide intraductal components towards the periphery were proven histopathologically in three out of 60 (5.0%) cancers. One cancer was located too close to the nipple and it was not possible to measure the intraductal component towards the nipple. US and MRI could accurately detect wide intraductal components towards the nipple in 14 and 8 cancers, respectively, out of 17 cancers. Sensitivity, specificity and accuracy for detection of wide intraductal components towards the nipple by US were 87.5, 88.3, and 88.1%, respectively. Sensitivity, specificity and accuracy for detection of wide intraductal components towards the nipple by MRI were 50, 79.1, and 72.1%, respectively. When the results of both diagnostic methods namely US and MRI were combined, sensitivity rose to 93.7%, specificity was 72.1% and accuracy was 78.0%.

CONCLUSION

Although ultrasound is more sensitive than MRI in the delineation of intraductal extension towards the nipple, there is no statistically significant difference in overall accuracy between the two modalities.

Fast generalized cross-validation algorithm for sparse model learning

We propose a fast, incremental algorithm for designing linear regression models. The proposed algorithm generates a sparse model by optimizing multiple smoothing parameters using the generalized cross-validation approach. The performances on synthetic and real-world data sets are compared with other incremental algorithms such as Tipping and Faul's fast relevance vector machine, Chen et al.'s orthogonal least squares, and Orr's regularized forward selection. The results demonstrate that the proposed algorithm is competitive.

Altered PPARgamma expression and activation after transient focal ischemia in rats

Stroke is a devastating disease with limited treatment options. Recently, we found that the peroxisome proliferator-activated receptor-gamma (PPARgamma) agonists troglitazone and pioglitazone reduce injury and inflammation in a rat model of transient cerebral ischemia. The mechanism of this protection is unclear, as these agents can act through PPAR-gamma activation or through PPAR-gamma-independent mechanisms. Therefore, we examined PPAR-gamma expression, DNA binding and transcriptional activity following stroke. In addition, we used a PPAR-gamma antagonist, T0070907, to determine the role of PPAR-gamma during ischemia. Using immunohistochemical techniques and real-time PCR, we found low levels of PPAR-gamma mRNA and PPAR-gamma immunoreactivity in nonischemic brain; however, PPAR-gamma expression dramatically increased in ischemic neurons, peaking 24 h following middle cerebral artery occlusion. Interestingly, we found that in both vehicle- and agonist-treated brains, DNA binding was reduced in the ischemic hemisphere relative to the contralateral hemisphere. Expression of a PPAR-gamma target gene, lipoprotein lipase, was also reduced in ischemic relative to nonischemic brain. Both DNA binding and lipoprotein lipase expression were increased by the addition of the PPAR-gamma agonist rosiglitazone. Finally, we found that rosiglitazone-mediated protection after stroke was reversed by the PPAR-gamma antagonist T0070907. Interestingly, infarction size was also increased by T0070907 in the absence of PPAR-gamma agonist, suggesting that endogenous PPAR-gamma ligands may mitigate the effects of cerebral ischemia.

Diaphragmatic pathology: a cause of clinically unexplained death in the perinatal/paediatric age group

Sudden unexpected death in infancy and childhood requires a 'full' post-mortem investigation. Guidance from the Royal College of Pathologists recommends sampling of all the major organs. However, the diaphragm does not feature in this or in most lists of routine histology. Our aim is to emphasize the importance of sampling the diaphragm for histological examination during autopsy. We describe three autopsy cases of clinically unexplained death in the perinatal and paediatric age group that showed significant pathology of the diaphragm. In Case 1, a previously healthy five-year-old girl collapsed suddenly and died four days later. In Case 2, an eight-month-old infant had repeated episodes of respiratory arrest that culminated in death. Autopsy demonstrated a predominantly diaphragmatic myositis. In Case 3 a female neonate had a respiratory arrest three days after birth and died less than a month later. Autopsy showed multiple large calcified necrotic fibres in the diaphragm. The diaphragm is seldom sampled at autopsy. In the first two cases a predominantly diaphragmatic myositis was either the direct or underlying cause of death. In the third case long-standing diaphragmatic pathology of uncertain cause may have contributed to the original respiratory arrest. Had the diaphragm not been examined histologically, the cause of death would have remained unascertained in these cases. In cases of sudden death in infancy and childhood, failure to reach a diagnosis may lead to undue suspicion falling upon the child's carers. This underscores the need for full histology at post-mortem in child deaths, including diaphragmatic sampling.

Peroxisome proliferator-activated receptor-γ ligands reduce inflammation and infarction size in transient focal ischemia

Newly developed insulin-sensitizing agents, which target the nuclear receptor peroxisome proliferator-activated receptor-gamma have recently been appreciated to exhibit potent anti-inflammatory actions. Since stroke is associated with an intense inflammatory response, we reasoned that these agents may ameliorate injury from stroke. We report that administration of troglitazone or pioglitazone 24 h before and at the time of cerebral infarction dramatically reduced infarction volume and improved neurological function following middle cerebral artery occlusion in rats. Furthermore, we find that delayed therapy also significantly reduced infarct volume. The brains of the drug-treated animals displayed reduced inflammation as evidenced by decreased immunoreactivity for microglial/macrophage markers and reduced protein and mRNA for interleukin-1beta, cyclooxygenase-2 and inducible nitric oxide synthase. We argue that the beneficial effects of these drugs are likely due to reduced expression of these inflammatory mediators, which are known to exacerbate ischemic injury following stroke. These results are of particular relevance to diabetic patients chronically treated with these agents who may benefit from the neuroprotective actions of these drugs.

Comparison of the effect of surface roughness on the micro/nanotribological behavior of ultra-high-molecular-weight polyethylene (UHMWPE) in air and bovine serum solution

Tribological properties of materials used in biomedical implants critically affect the performance of the implant. A UHMWPE cup paired with a ceramic ball is a popular combination for implants due to its relatively low wear rate. In this study we investigate the effect of surface roughness of UHMWPE on the friction behavior and onset of wear in a UHMWPE/silicon nitride interface in both dry air and bovine serum environments. Microscale multi-asperity contact is examined using a ball-on-flat reciprocating microtribometer. Nanoscale single-asperity contact and surface topography are examined using atomic force microscopy. Friction was found to increase with a decrease in surface roughness of the UHMWPE sample in air, which is due to an increase in real area of contact. This trend was seen to disappear or even reverse in serum. This is due to an increase in the interfacial shear stress of the UHMWPE surface when exposed to the serum. This increase is believed to be caused by an adhered layer of protein on the UHMWPE surface.

Effects of flux enhancing polymer on the characteristics of sludge in membrane bioreactor process

A newly developed membrane performance enhancer (MPE) was used to prevent membrane fouling in a membrane bioreactor (MBR) process. It transpired that 1,000 mg/l of MPE reduced polysaccharide levels from 41 mg/I to 21 mg/I on average under the experimental condition. Repeated experiments also confirmed that 50-1,000 mg/l of MPE could reduce membrane fouling significantly and increase the intervals between membrane cleanings. Depending on MPE dosages and experimental conditions, trans-membrane pressure (TMP) increase was suppressed for 20-30 days, while baseline TMP surged within a few days. In addition, MPE allowed MBR operation even at 50,000 mg/l of total solid and reduced permeate COD. However, no evidence of toxicity for sludge was found from respiratory works.

Mechanical property measurements of nanoscale structures using an atomic force microscope

This paper describes nanometer-scale bending tests of fixed single-crystal silicon (Si) and silicon dioxide (SiO2) nanobeams using an atomic force microscope (AFM). The technique is used to evaluate elastic modulus of the beam materials and bending strength of the beams. Nanometer-scale Si beams with widths ranging from 200 to 800 nm were fabricated on a Si diaphragm using field-enhanced anodization using an AFM followed by anisotropic wet etching. Subsequent thermal oxidation of Si beams was carried out to create SiO2 beams. Results from the bending tests indicate that elastic modulus values are comparable to bulk values. However, the bending strength appears to be higher for these nanoscale structures than for large-scale specimens. Observations of the fracture surface and calculations of the crack length from Griffith's theory appear to indicate that the maximum peak-to-valley distance on the beam top surfaces influence the values of the observed bending strengths.

Predictive Approaches for Choosing Hyperparameters in Gaussian Processes

Gaussian processes are powerful regression models specified by parameterized mean and covariance functions. Standard approaches to choose these parameters (known by the name hyperparameters) are maximum likelihood and maximum a posteriori. In this article, we propose and investigate predictive approaches based on Geisser's predictive sample reuse (PSR) methodology and the related Stone's cross-validation (CV) methodology. More specifically, we derive results for Geisser's surrogate predictive probability (GPP), Geisser's predictive mean square error (GPE), and the standard CV error and make a comparative study. Within an approximation we arrive at the generalized cross-validation (GCV) and establish its relationship with the GPP and GPE approaches. These approaches are tested on a number of problems. Experimental results show that these approaches are strongly competitive with the existing approaches.

Exposure of developing oligodendrocytes to cadmium causes HSP72 induction, free radical generation, reduction in glutathione levels, and cell death

Primary cultures of oligodendrocytes were used to study the toxic effects of cadmium chloride. Cell viability was evaluated by the mitochondrial dehydrogenase activity and confirmed by propidium iodide (PI) fluorescence staining. The expression of the 72 kDa stress protein, HSP72, was assayed by Western blot analysis. The results showed that Cd(2+)-induced toxicity was dependent on the time and dose of exposure, as well as on the developmental stage of the cultures. Oligodendrocyte progenitors were more vulnerable to Cd(2+) toxicity than were mature oligodendrocytes. Mature oligodendrocytes accumulated relatively higher levels of Cd(2+) than did progenitors, as determined by (109)CdCl(2) uptake; treatment with the metal ion caused a more pronounced reduction in intracellular glutathione levels and significantly higher free radical accumulation in progenitors. The latter could explain the observed differences in Cd(2+) susceptibility. HSP72 protein expression was increased both in progenitors and in mature cells exposed to Cd(2+). Pretreatment with N-acetylcysteine, a thiocompound with antioxidant activity and a precursor of glutathione, prevented Cd(2+)-induced (i) reduction in glutathione levels and (ii) induction of HSP72 and diminished (i) Cd(2+) uptake and (ii) Cd(2+)-evoked cell death. In contrast, buthionine sulfoximine, an inhibitor of gamma-glutamyl-cysteine synthetase, depleted glutathione, and potentiated the toxic effect of Cd(2+). These results strongly suggest that Cd(2+)-induced cytotoxicity in oligodendrocytes is mediated by reactive oxygen species and is modulated by glutathione levels.

Thrombolysis for acute stroke: is it for everyone?

To date, there is only one US Food and Drug Administration-approved treatment for stroke. Many patients have benefited after receiving rt-PA within 3 hours of acute stroke. Although the risk of hemorrhagic conversion is real, the patients at high risk for this complication are often the same patients most at risk for poor outcome secondary to their ischemic events. In this article, we review the data supporting the use of thrombolytics, both intravenously and intra-arterially, as well as patient selection criteria. Furthermore, we provide a framework for administering rt-PA and discuss the future of thrombolytic therapy.

Acute leptomeningitis due to Bacillus anthracis. A case report

A fatal case of anthrax meningitis in a 45-year-old woman is presented from Karnataka State, South India. The clinical, microbiological and histopathological profile is presented.