Swallow syncope: reflex or reflux?

A 51-year-old man presented with symptoms of syncope on consuming solid foods. He had a 5 year history of intermittent symptoms on eating only solids and his cardiovascular investigations revealed bradycardia during food ingestion. He was treated by insertion of a pacemaker with cessation of his syncopal symptoms.     

The effect of experimental streptococcus infection in myocarditis on some biochemical and inflammatory markers in albino rats

Background

Myocarditis is an uncommon disease that presents with a wide range of symptoms in children and adults. It is histologically characterized by varying degrees of myocardialnecrosis, edema and cellular infiltration myocardial inflammation is a nonspecificresponse to many triggers such as bacterial infection, cardio toxic agents, ormechanical injury.

Objective

This study was carried out to investigate the experimental Streptococcus faecalis induction of myocarditis and its effect on some blood parameters, inflammatory markers and histopathological changes in male albino rats.

Methods

Rats were infected by intraperitoneal injection of 10 8 CFU/ml of Streptococcus faecalis and sacrificed after one, two and seven days post infection. Biochemical analyses of blood were carried out to investigate the serum biomarkers of inflammation, liver function tests, cardiac enzymes & kidney function tests.

Results

All biochemical analyses showed statistically significant increase in the measured parameters due to bacterial infections except for blood urea which appear to be normal. A significant positive correlation was observed between lactate dehydrogenase enzyme (LDH) with creatinine (r =0.778, P<0.01). In the 7 days group, there were significant positive correlations between aspartate aminotransferase (AST) and alanine aminotransferase (ALT) (r=0.675, P<0.05), erythrocyte sedimentation rate (ESR) with Urea (r=0.659, P<0.05) and alkaline phosphatase (ALP) with C-reactive protein (CRP) (r=0.765, p<0.01).

Conclusion

Many of these biomarkers will provide important new insights into pathophysiology and aid in the diagnosis and management of cardiovascular patients.     

Immune Cell‐Derived C3a and C5a Costimulate Human T Cell Alloimmunity

Emerging evidence indicates that complement provides costimulatory signals for murine T cells but whether complement impacts human T cells remains unclear. We observed production of complement activation products C3a and C5a during in vitro cultures of human T cells responding to allogeneic dendritic cells (DC). Both partners expressed the receptors for C3a (C3aR) and C5a (C5aR) and C3aR‐ and C5aR‐antagonists inhibited T cell proliferation. Recombinant C3a/C5a promoted CD4⁺ T cell expansion, bypassed the inhibitory effects of CTLA4‐Ig, and induced AKT phosphorylation, the latter biochemically linking C3aR/C5aR to known T cell signaling pathways. Lowering DC C3a/C5a production by siRNA knockdown of DC C3 reduced T cell alloresponses. Conversely downregulating DC expression of the complement regulatory protein decay–accelerating factor increased immune cell C3a/C5a and augmented T cell proliferation, identifying antigen presenting cells as the dominant complement source. Pharmacological C5aR blockade reduced graft versus host disease (GVHD) scores, prolonged survival, and inhibited T cell responses in NOD scid γc^null mouse recipients of human peripheral blood mononuclear cells, verifying that the mechanisms apply in vivo. Together our findings unequivocally document that immune cell–derived complement impacts human T cell immunity and provide the foundation for future studies targeting C3aR/C5aR as treatments of GVHD and organ transplant rejection in humans.     

Deep Convolutional Neural Networks for Endotracheal Tube Position and X-ray Image Classification: Challenges and Opportunities

The goal of this study is to evaluate the efficacy of deep convolutional neural networks (DCNNs) in differentiating subtle, intermediate, and more obvious image differences in radiography. Three different datasets were created, which included presence/absence of the endotracheal (ET) tube (n = 300), low/normal position of the ET tube (n = 300), and chest/abdominal radiographs (n = 120). The datasets were split into training, validation, and test. Both untrained and pre-trained deep neural networks were employed, including AlexNet and GoogLeNet classifiers, using the Caffe framework. Data augmentation was performed for the presence/absence and low/normal ET tube datasets. Receiver operating characteristic (ROC), area under the curves (AUC), and 95% confidence intervals were calculated. Statistical differences of the AUCs were determined using a non-parametric approach. The pre-trained AlexNet and GoogLeNet classifiers had perfect accuracy (AUC 1.00) in differentiating chest vs. abdominal radiographs, using only 45 training cases. For more difficult datasets, including the presence/absence and low/normal position endotracheal tubes, more training cases, pre-trained networks, and data-augmentation approaches were helpful to increase accuracy. The best-performing network for classifying presence vs. absence of an ET tube was still very accurate with an AUC of 0.99. However, for the most difficult dataset, such as low vs. normal position of the endotracheal tube, DCNNs did not perform as well, but achieved a reasonable AUC of 0.81.     

Prevention of acquired transient defect in platelet plug formation by infused prostacyclin

Cardiopulmonary bypass in baboons produced transient severe platelet dysfunction (bleeding times prolonged to 27.8 +/- 1.4 min compared with 3.9 +/- 0.7 baseline) that was associated with a parallel release of platelet alpha-granule proteins into plasma (platelet factor 4 and beta- thromboglobulin levels of 28.8 +/- 9.3 and 20.0 +/- 1.8 ng/ml, respectively) and their clearance into urine with a reciprocal depletion from circulating platelets. In contrast, platelet-dense granules did not undergo significant release. The bleeding times normalized rapidly following bypass (8.5 +/- 1.4 min at 1 hr). The infusion of prostacyclin (PGI2) into the bubble oxygenator during bypass (40--80 ng/kg/min) prevented the prolongation in bleeding time (p less than 0.01 compared with untreated control values) but did not block the release of alpha-granule proteins. Dosages outside this range were associated with prolonged bleeding times. These results show that transient platelet dysfunction occurring during cardiopulmonary bypass represents activation of platelets independent of alpha or dense granule release and is blocked by potent short-acting inhibition of platelet function using PGI2 infused into the oxygenator apparatus at optimal therapeutic doses.