Huy P. Pham

EBM: an entropy-based model to infer social strength from spatiotemporal data

The ubiquity of mobile devices and the popularity of location-based-services have generated, for the first time, rich datasets of peoples location information at a very high fidelity. These location datasets can be used to study peoples behavior - for example, social studies have shown that people, who are seen together frequently at the same place and at the same time, are most probably socially related. In this paper, we are interested in inferring these social connections by analyzing peoples location information, which is useful in a variety of application domains from sales and marketing to intelligence analysis. In particular, we propose an entropy-based model (EBM) that not only infers social connections but also estimates the strength of social connections by analyzing peoples co-occurrences in space and time. We examine two independent ways: diversity and weighted frequency, through which co-occurrences contribute to social strength. In addition, we take the characteristics of each location into consideration in order to compensate for cases where only limited location information is available. We conducted extensive sets of experiments with real-world datasets including both peoples location data and their social connections, where we used the latter as the ground-truth to verify the results of applying our approach to the former. We show that our approach outperforms the competitors.

Update on massive transfusion

Massive haemorrhage requires massive transfusion (MT) to maintain adequate circulation and haemostasis. For optimal management of massively bleeding patients, regardless of aetiology (trauma, obstetrical, surgical), effective preparation and communication between transfusion and other laboratory services and clinical teams are essential. A well-defined MT protocol is a valuable tool to delineate how blood products are ordered, prepared, and delivered; determine laboratory algorithms to use as transfusion guidelines; and outline duties and facilitate communication between involved personnel. In MT patients, it is crucial to practice damage control resuscitation and to administer blood products early in the resuscitation. Trauma patients are often admitted with early trauma-induced coagulopathy (ETIC), which is associated with mortality; the aetiology of ETIC is likely multifactorial. Current data support that trauma patients treated with higher ratios of plasma and platelet to red blood cell transfusions have improved outcomes, but further clinical investigation is needed. Additionally, tranexamic acid has been shown to decrease the mortality in trauma patients requiring MT. Greater use of cryoprecipitate or fibrinogen concentrate might be beneficial in MT patients from obstetrical causes. The risks and benefits for other therapies (prothrombin complex concentrate, recombinant activated factor VII, or whole blood) are not clearly defined in MT patients. Throughout the resuscitation, the patient should be closely monitored and both metabolic and coagulation abnormalities corrected. Further studies are needed to clarify the optimal ratios of blood products, treatment based on underlying clinical disorder, use of alternative therapies, and integration of laboratory testing results in the management of massively bleeding patients.

Therapeutic plasma exchange for the treatment of anti-NMDA receptor encephalitis

Anti‐N‐methyl‐D‐aspartate receptor (NMDA‐R) encephalitis is thought to be one of the common paraneoplastic‐associated encephalitides. Between February 2001 and February 2011, nine patients were diagnosed with this disorder at Columbia University Medical Center: eight females (mean age 23 years) and one male (3 years of age). Four female patients had ovarian teratomas, which were removed as part of their treatment. Therapeutic plasma exchange (TPE) was used as one of the treatment modalities in addition to immunosuppressive therapy, including corticosteroids, intravenous immunoglobulin (IVIG), and/or rituximab. A total of 56 TPE procedures were performed in these patients on alternate days (range, 5–14 procedures/patient). Approximately 1 plasma volume (PV) was processed for all patients; 5% albumin and 0.9% normal saline were used as replacement fluid. Complications occurred in 20% of TPE procedures; 9% were possibly due to underlying disease. The remaining 11% of complications were hypotensive episodes that rapidly responded to either a fluid bolus or a vasopressor treatment. One patient demonstrated immediate clinical improvement after three TPE treatments, and four patients had significant improvement at time of discharge from the hospital. Long‐term follow‐up showed that early initiation of TPE appears to be beneficial, and patients who received IVIG after TPE did better than those who received IVIG before TPE. However, the number of patients in this series is too small to provide statistically significant conclusions. Overall, TPE is a relatively safe treatment option in patients with anti‐NMDA‐R encephalitis. Further studies are needed to elucidate the benefit of TPE in this disease. J. Clin. Apheresis, 2011.

Towards integrating real-world spatiotemporal data with social networks

As the popularity of social networks is continuously growing, collected data about online social activities is becoming an important asset enabling many applications such as target advertising, sale promotions, and marketing campaigns. Although most social interactions are recorded through online activities, we believe that social experiences taking place offline in the real physical world are equally if not more important. This paper introduces a geo-social model that derives social activities from the history of peoples movements in the real world, i.e., who has been where and when. In particular, from spatiotemporal histories, we infer real-world co-occurrences - being there at the same time - and then use co-occurrences to quantify social distances between any two persons. We show that straightforward measures either do not scale or may overestimate the strength of social connections by giving too much weight to coincidences.

Cryoprecipitate AHF vs. fibrinogen concentrates for fibrinogen replacement in acquired bleeding patients – an economic evaluation

Fibrinogen repletion in patients with acquired bleeding disorders can be accomplished by transfusing cryoprecipitate AHF (cryo) or fibrinogen concentrate (FC); thus, we undertook an economic evaluation from the transfusion service perspective regarding the use of cryo vs. FC in patients with acquired bleeding.

Real-Time Multi-Criteria Social Graph Partitioning: A Game Theoretic Approach

Graph partitioning has attracted considerable attention due to its high practicality for real-world applications. It is particularly relevant to social networks because it enables the grouping of users into communities for market analysis and advertising purposes. In this paper, we introduce RMGP, a type of real-time multi-criteria graph partitioning for social networks that groups the users based on their connectivity and their similarity to a set of input classes. We consider RMGP as an on-line task, which may be frequently performed for different query parameters (e.g., classes). In order to overcome the serious performance issues associated with the large social graphs found in practice, we develop solutions based on a game theoretic framework. Specifically, we consider each user as a player, whose goal is to find the class that optimizes his objective function. We propose algorithms based on best-response dynamics, analyze their properties, and show their efficiency and effectiveness on real datasets under centralized and decentralized scenarios.

Report of the ASFA apheresis registry study on Wilson's disease

Wilsons disease is a rare autosomal recessive genetic disorder that results in accumulation of copper in the liver, brain, cornea and kidney. Therapeutic plasma exchange (TPE) has been used to remove copper and provide a bridge to liver transplantation. We report here the collective experiences through the ASFA apheresis registry on Wilsons disease.

Granulocyte transfusion therapy in pediatric patients after hematopoietic stem cell transplantation: a 5-year single tertiary care center experience.

Background: Granulocyte transfusion (GTx) has been used in neutropenic patients to treat infections; however, there are few studies that document its efficacy, especially in pediatric patients after hematopoietic stem cell transplantation (HSCT). We, therefore, reviewed the use of GTx in these patients. Materials and Methods: A retrospective observational analysis was performed on all pediatric HSCT patients between January 2005 and January 2010 who met our institution’s criteria for GTx and received more than 1 GTx. Unstimulated granulocyte donors were used until June 2007, followed by dexamethasone-stimulated donors thereafter. Outcomes were infection clearance, safety profile of GTx, and 30-day survival. Results: One hundred fifty-three GTxs were administered to 16 pediatric HSCT patients. Indications for GTx: bacterial (69%), fungal (19%), and combined infection (12%). Concurrent infections, mostly bacterial, developed in 60% patients. One adverse reaction (pulmonary toxicity) was reported. The absolute neutrophil count of the stimulated products was significantly higher compared with the unstimulated products; however, neither the average number of granulocytes transfused by weight nor outcomes difference was noticed between these groups. Conclusions: GTx is safe in neutropenic and infected pediatric patients after HSCT. However, no difference in the outcomes was noticed between the group that received stimulated products and the group that received unstimulated products.

How we approach a patient with symptoms of leukostasis requiring emergent leukocytapheresis

Hyperleukocytosis can induce leukostasis, which can lead to vascular obstructions (usually in the lungs and central nervous system), tumor lysis syndrome, and disseminated intravascular coagulation. Although it has not been conclusively shown to improve long‐term outcome, leukocytapheresis may be used as part of the management of hyperleukocytosis with or without leukostasis to rapidly reduce the white blood cell (WBC) burden. Since leukocytapheresis only temporarily decreases the WBC count, early initiation of more definite therapy, such as hydroxyurea and/or chemotherapy, is essential. In this article, clinical assessment of the patients clinical status to determine the need for leukocytapheresis as well as a general guideline for management of the technical aspects and complications of the procedure are discussed.

How to approach an apheresis consultation using the American Society for Apheresis guidelines for therapeutic apheresis procedures

Therapeutic apheresis (TA) is a treatment modality currently being used in many disease conditions. However, the decision to treat a patient with TA depends on many factors, including but not limited to the most likely diagnosis the patient has and whether there is a rationale for TA to be used as a treatment modality, the risk versus benefit ratio of the treatment and the technical aspects of the procedure if apheresis is performed. The guidelines on the use of therapeutic apheresis in clinical practice – evidence‐based approach from the writing committee of the American Society for Apheresis (ASFA) are update every 3 years and are based on the review of the most up to date medical literature addressing the rationale as well as technical aspect of apheresis. The guidelines are meant to help with clinical decision‐making in apheresis consultations and to encourage research on the use of apheresis for novel indications. The format used for the different disease conditions is one‐page fact sheet. In this article, the development and application of these fact sheets in those guidelines are discussed along with an example for each of ASFAs four categories.