Simplified parametric methods for [11C]PIB studies

The purpose of the present study was to evaluate the performance of various parametric reference tissue models for quantification of [11C]PIB studies. Several models with and without fixing the reference tissue efflux rate constant (k'(2)) were investigated using both simulations and clinical data. The following parametric methods were evaluated: receptor parametric mapping (basis function implementation of the simplified reference tissue model with and without fixed k'(2)), reference Logan, and several multi-linear reference tissue methods (again with and without fixed k'(2)). In addition, standardised uptake value ratios with cerebellum (SUV(r)) were evaluated. Simulations were used to assess the effects of variation in flow (R(1)), fractional blood volume (V(b)) and binding potential (BP(ND)) itself on precision and accuracy of parametric BP(ND). For clinical studies, most parametric methods showed comparable performance, with poorest results for SUV(r). Best performance was obtained for receptor parametric mapping (RPM2) and one of the multi-linear reference tissue models (MRTM2), both with fixed k'(2): BP(ND) outcome was less affected by noise and the images showed better contrast than other tested methods. RPM2 and MRTM2 also provided best accuracy and precision in the simulation studies and are therefore the methods of choice for parametric analysis of clinical [11C]PIB studies.     

Chief complaints, diagnoses, and medications prescribed seven weeks post-Katrina in New Orleans

BACKGROUND: In the aftermath of Hurricane Katrina, widespread flooding devastated the New Orleans healthcare system. Prior studies of post-hurricane healthcare do not consistently offer evidence-based recommendations for re-establishing patient care post-disaster. The primary objective of this study is to examine associations between patient characteristics, chief complaints, final diagnoses, and medications prescribed at a post-Katrina clinic to better inform strategic planning for post-disaster healthcare delivery (e.g., charitable donations of medications and medical supplies). METHODS: This study is a retrospective chart review of 465 patient visits from 02 September 2005 to 22 October 2005 at a post-Katrina clinic in New Orleans, Louisiana that was open for seven weeks, providing urgent care services in the central business district. Using logistic regression, the relationships between patient characteristics (date of visit, gender, age, evacuation status), type of chief complaint, final diagnosis, and type of medication prescribed was examined. RESULTS: Of 465 patients, 49.2% were middle-aged, 62.4% were men, 35% were relief workers, and 33.3% were evacuees; 35% of visits occurred in week five. Of 580 chief complaints, 71% were illnesses, 21% were medication refill requests, and 8.5% were injuries. Among 410 illness complaints, 25% were ears, nose, and throat (ENT)/dental, 17% were dermatologic, and 11% were cardiovascular. Most requested classes of medication refills for chronic medical conditions (n = 121) were cardiovascular (52%) and endocrine (24%). Most illness-related diagnoses (n = 400) were ENT/dental (18.2%), dermatologic (14.8%), cardiovascular (10.2%), and pulmonary (10.2%). Thirty-six percent of these diagnoses were infectious. Among 667 medications prescribed, 21% were cardiac agents, 13% pulmonary, 13% neurologic/musculoskeletal/pain, 11% antibiotics, 10% endocrine, and 9.3% anti-allergy. The likelihood of certain chief complaints, diagnoses, and medications prescribed varied with patient characteristics. CONCLUSIONS: Donations of certain classes of medications were more useful than others. Prevalence of select co-morbidities, the nature of patient involvement in recovery activities in the disaster area, and post-disaster health hazards may explain variations in chief complaints, diagnoses, and medications prescribed by patient characteristics.     

Ficoll-separated mononuclear cells from sepsis patients are contaminated with granulocytes

Objective To determine the cell content and purity of Ficoll-separated peripheral blood mononuclear cells and granulocyte isolates in sepsis patients compared to healthy controls. Design and setting Prospective study in the adult and pediatric intensive care departments of the Erasmus University Medical Center in the Netherlands. Patients Three sepsis patients (two adults, one child) and four healthy controls. Measurements and results Blood leukocytes were separated by Ficoll into an interface and a bottom fraction. The cell content and purity was analyzed by cytospin and flow-cytometric immunofluorescence. In sepsis patients, the interface consisted of 11–52% mononuclear cells only, due to high contamination with granulocytes (48–89%). This was in contrast to a high proportion of mononuclear cells (88–100%) in healthy controls. The bottom fraction showed a cell purity of ≥ 92% polymorphonuclear granulocytes in sepsis patients as well as in healthy controls. Conclusions Ficoll-separated leukocytes of sepsis patients are not suitable for studying mononuclear cells but can be used for studying granulocytes with high purity. The mononuclear cell fraction is highly contaminated with granulocytes. Additional separation techniques are necessary to obtain a pure cell fraction.     

Peripheral nerve regeneration is delayed in neuropilin 2-deficient mice

Peripheral nerve transection or crush induces expression of class 3 semaphorins by epineurial and perineurial cells at the injury site and of the neuropilins neuropilin-1 and neuropilin-2 by Schwann and perineurial cells in the nerve segment distal to the injury. Neuropilin-dependent class 3 semaphorin signaling guides axons during neural development, but the significance of this signaling system for regeneration of adult peripheral nerves is not known. To test the hypothesis that neuropilin-2 facilitates peripheral-nerve axonal regeneration, we crushed sciatic nerves of adult neuropilin-2-deficient and littermate control mice. Axonal regeneration through the crush site and into the distal nerve segment, repression by the regenerating axons of Schwann cell p75 neurotrophin receptor expression, remyelination of the regenerating axons, and recovery of normal gait were all significantly slower in the neuropilin-2-deficient mice than in the control mice. Thus, neuropilin-2 facilitates peripheral-nerve axonal regeneration.