NIBRS Data Available for Secondary Analysis

The NIBRS data program currently being implemented by the FBI and local lawenforcement agencies has by now produced sufficient data for archiving anddistribution. Although not representative of crime in the United States, existing NIBRS data can be used to investigate the nature of crimesknown to the police compared to the traditional UCR data. The Bureau ofJustice Statistics has requested the National Archive of Criminal JusticeData to store and make NIBRS data available to interested users. The datafrom 1996 will shortly be available from the NACJD web site. The 1996 datacontain almost 6.5 million records and the FBI's full file includes about 361 Mbytes of data. The data have been disaggregated from the FBI's complex single file into 11 segment levels or record types. This makes theindividual record types easier and faster to analyze than using the fullfile, which more closely resembles a relational database than a hierarchicalfile. However, splitting apart the record types requires that specialprocedures be used to merge files of different record types, which would benecessary if a user were interested in analyzing variables appearing in morethan one record type (e.g., comparing offender and victim ages). These procedures are described, and a test comparing the time to run a simple frequencycount using the full file against the merged files shows that using themerged files is considerably more efficient. Also discussed are some futuredevelopments to facilitate the analysis of NIBRS data.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/45110/1/10940_2004_Article_220510.pd

Gadolinium-enhanced magnetic resonance angiography of abdominal aortic aneurysms

AbstractPurpose: The objective of this study was to assess the usefulness of gadolinum-enhanced magnetic resonance angiography (MRA) for defining anatomic features relevant to performing aortic surgery for aneurysmal disease.Methods: Anatomic data defined by MRA, including abdominal aortic aneurysm (AAA) size and character, as well as the status of the celiac, mesenteric, renal, and iliac arteries, were correlated with angiography, ultrasonography, computed tomography, or operative data in 43 patients. Five MRA sequences were obtained in an hour-long examination optimized for aortoiliac, splanchnic, and renal artery imaging at 1.5 T in a body coil. Four of the sequences were performed during or after infusion of gadolinium to improve image quality.Results: MRA correctly defined the maximum aneurysm diameter, as well as its proximal and distal extent in all patients. MRA detected 33 of 35 significant stenoses among 153 splanchnic, renal, or iliac branches examined (sensitivity = 94% and specificity = 98%). MRA did not resolve the degree of aortic branch stenotic disease sufficiently to precisely grade its severity. MRA did not reliably define the status of the inferior mesenteric artery, lumbar arteries or internal iliac arteries. One ruptured AAA and one inflammatory AAA were correctly diagnosed by MRA. No patient had a contrast reaction or contrast-induced renal toxicity related to administration of gadolinium.Conclusion: Gadolinium-enhanced MRA of AAA provides appropriate, essential anatomic information for aortic reconstructive surgery in a 1-hour examination devoid of contrast-related renal toxicity or catheterization-related complications attending conventional arteriography. (J VASC SURG 1995;21:656-69.

A novel protamine variant reversal of heparin anticoagulation in human blood in vitro

AbstractPurpose: Protamine reversal of heparin anticoagulation during cardiovascular surgery may cause severe hypotension and pulmonary hypertension. A novel protamine variant, [+18RGD], has been developed that effectively reverses heparin anticoagulation without toxicity in canine experiments. Heretofore, human studies have not been undertaken. This investigation hypothesized that [+18RGD] would effectively reverse heparin anticoagulation of human blood in vitro. Methods: Fifty patients who underwent anticoagulation therapy during vascular surgery had blood sampled at baseline and 30 minutes after receiving heparin (150 IU/kg). Activated clotting times were used to define specific quantities of [+18RGD] or protamine necessary to completely reverse heparin anticoagulation in the blood sample of each patient. These defined amounts of [+18RGD] or protamine were then administered to the heparinized blood samples, and percent reversals of activated partial thromboplastin time, thrombin clotting time, and antifactor Xa/IIa levels were determined. In addition, platelet aggregation assays, as well as platelet and white blood cell counts were performed. Results: [+18RGD] and protamine were equivalent in reversing heparin as assessed by thrombin clotting time, antifactor Xa, antifactor IIa levels, and white blood cell changes. [+18RGD], when compared with protamine, was superior in this regard, as assessed by activated partial thromboplastin time (94.5 ± 1.0 vs 86.5 ± 1.3%δ, respectively; p < 0.001) and platelet declines (–3.9 ± 2.9 vs –12.8 ± 3.4 per mm3, respectively; p = 0.048). Platelet aggregation was also decreased for [+18RGD] compared with protamine (23.6 ± 1.5 vs 28.5 ± 1.9%, respectively; p = 0.048). Conclusions: [+18RGD] was as effective as protamine for in vitro reversal of heparin anticoagulation by most coagulation assays, was statistically more effective at reversal than protamine by aPTT assay, and was associated with lesser platelet reductions than protamine. [+18RGD], if less toxic than protamine in human beings, would allow for effective clinical reversal of heparin anticoagulation. (J Vasc Surg 1997;26:1043-8.

A Preliminary Study of the Impact of Case Specificity on Computer-Based Assessment of Medical Student Clinical Performance

The implications of case specificity of two computer-based clinical simulation examination cases (CBX) were examined by a classical measurement approach and by a Bayesian analysis of test characteristics. The CBXs (a surgery and an ob/gyn case) were designed by the National Board of Medical Examiners and administered to 163 University of Michigan Medical School students. The results indicate that the students performed differently on the two cases, the surgery case appearing to be more difficult. The ob/gyn case had greater sensitivity (more accuracy in passing competent students), whereas the surgery case had greater specificity (more accuracy in failing noncompetent students). The differences between the cases and evidence of case specificity raise the issue of an exam's objective and the acceptable type of classification error These results suggest that additional studies are required before widespread use of such exams can be implemented in "high stakes" situations for licensure purposes.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/67879/2/10.1177_016327879401700304.pd