Validation of Probabilistic Linkage to Match De-identified Ambulance Records to a State Trauma Registry

Objectives: To validate the accuracy of using probabilistic linkage for matching de‐identified ambulance records to a state trauma registry. Methods: This was a retrospective cohort analysis. Three thousand nine hundred nineteen true matches between ambulance and state trauma registry data from 1998 to 2003 were identified by deterministic matching on trauma identification number and verified by human review. Two thousand thirty‐eight ambulance records from trauma patients not meeting criteria for a true match, and an identical number of trauma registry records randomly selected from the one local county served by a different EMS provider, were included as nonmatches. There were 17 variables considered for linkage, which included the following: age, gender, race, county, hospital, date, rural setting, call and arrival times, mechanism, penetrating injury, vital signs, intubation, and intoxication. Probabilistic linkage was used to link the two data sets, using seven different combinations of common variables (maximum, 17; minimum, 4). The sensitivity and specificity of identifying true matches and nonmatches (95% confidence intervals [95% CI]) were calculated for each combination of variables. Results: Using all 17 available variables, 3,766 of 3,919 true matches were appropriately linked (sensitivity, 96.1%; 95% CI = 95.4% to 96.7%), with eight mismatches (specificity, 99.6%; 95% CI = 99.2% to 99.8%). Sensitivity fell below 95% with < 15 variables; however, sensitivity was very dependent on the inclusion of variables with high discriminatory power. Specificity remained >98% regardless of the number of variables included. Conclusions: Probabilistic linkage is a valid method for matching ambulance records to a trauma registry without the use of patient identifiers; however, the sensitivity of identifying true matches is critically dependent on the number and type of common variables included in the analysis.     

Rat amylin: cloning and tissue-specific expression in pancreatic islets.

Amyloid deposits in the islets of Langerhans of the pancreas are a common finding in non-insulin-dependent diabetes mellitus. The main protein constituent of these deposits is a 37-amino acid peptide known as amylin that resembles calcitonin gene-related peptide, a neuropeptide. We have isolated cDNA clones corresponding to the rat amylin precursor from an islet cDNA library and we show that this peptide is encoded in a 0.9-kilobase mRNA that is translated to yield a 93-amino acid precursor. The amylin peptide is bordered by dibasic residues, suggesting that it is proteolyzed like calcitonin gene-related peptide. The peptide sequences flanking the amylin sequence do not resemble the calcitonin gene-related peptide flanking sequences. RNA hybridization studies show that amylin mRNA is abundant in the islets of Langerhans but is not present in the brain or seven other tissues examined. Dietary changes, such as fasting or fasting and refeeding, have little effect on amylin mRNA expression. This tissue specificity suggests that amylin is involved in specific signaling pathways related to islet function.     

Sequence Analysis of the RNA Polymerase Gene of Foot-and-Mouth Disease Virus Serotype Asia1

The complete nucleotide (nt.) sequence of the RNA polymerase (3D) gene and 81 nt. in the 3-untranslated region of foot-and-mouth disease virus (FMDV) serotype Asia1 (IND63/72) was determined and compared with the sequence of other FMDV serotypes. The 3D genomic region was 1410 nt. long encoding 470 amino acids with an inframe stop codon (TAA) at nt. position 1411–1413. The deduced amino acid sequence of the protein showed 8 conserved motifs as reported in other picornaviruses, 2 of which are 100% identical across the serotypes. Antigenic regions in the polymerase protein were predicted and found to be located at the N-terminus of the protein. The phylogenetic analysis showed that the FMD viruses were segregated into different clusters based on geographical origin; the Asia1 virus did not cluster tightly with any of the geographical groups.     

Comparison of ultrasonographic findings in spontaneous abortions with normal and abnormal karyotypes

To determine whether ultrasonographic findings can predict the karyotype of spontaneous abortions, 137 pregnancies (54 spontaneous, 83 assisted ovulatory cycles) that subsequently aborted and had chromosome analysis performed on the products of conception were studied ultrasonographically. Transvaginal ultrasound was performed using an Acuson 128XP/10 with 7.5 MHz probe. The numbers of empty gestational sacs, small and normal for gestational size, embryonic poles and embryos with documented cardiac activity were calculated. The frequency of each of these findings in pregnancies with normal and abnormal karyotypes was compared. Of the 137 spontaneous abortions, 51 had normal chromosome analyses and 86 had abnormal karyotypes (68 aneuploidies and 18 polyploidies). Ultrasonographic findings in the 51 karyotypically normal pregnancies included 16 (31%) with empty gestational sacs, and 35 (69%) with embryonic poles, of which 24 (69%) were at least 1 week smaller than expected for gestational age and 11 (31%) were the expected size. Embryonic cardiac activity was documented in 22 (63%) of the 35 embryonic poles. Amongst 86 pregnancies with abnormal karyotypes, similar frequencies of ultrasound findings were found: 23 (27%) with empty gestational sacs, 42 (67%) with embryonic poles smaller than expected for gestational age, and 50 (79%) embryos lost after documentation of embryonic cardiac activity. No differences in the frequency of ultrasonographic findings of empty gestational sacs, small embryonic pole and embryonic cardiac activity were observed between karyotypically normal and abnormal spontaneous abortions. Ultrasonographic findings cannot predict the karyotype of spontaneous abortions.