Chronic Fibrotic Changes in Experimental Pulmonary Embolization in the Rat Model

Comparative Medicine - OneHealth and Comparative Medicine Poster SessionIntroduction: Fat embolism, a subclinical event, occurs in many clinical settings, such as long bones fractures, liposuction and during cardiopulmonary bypass. Some cases, especially with trauma, result in fat embolism syndrome (FES), a serious manifestation of fat embolism. FES is reported to occur in 5-10% of major trauma cases and can produce profound respiratory problems that may culminate in adult respiratory distress syndrome (ARDS). Embolized fat is hydrolyzed by lipase into free fatty acids which have been shown by previous histological studies to be toxic to the lung. An animal model of fat embolism has been developed utilizing triolein given intravenously (i.v.) to rats. We hypothesized that i.v. triolein will produce histological changes in the lung that are similar to the changes seen in human FES. Methods: Following University animal care approval, unanesthetized Sprague Dawley rats (study n=13, control n=12) were injected with either triolein, 0.2 mL (study) or saline, 0.2 mL (control). Weights were recorded until necropsy at 3 weeks (n=13) and 6 weeks (n=12). Morphometric measurements were made on both H&E and fat-stained tissues from the lungs, heart, kidneys and spleen. All vessels were examined using high magnification fields. Arterial wall thickness (lumen patency) was calculated by vessel luminal and external diameters. The medial-adventitial ratio was calculated from the outer medial diameter divided by the outer adventitial diameter. These values were keyed into statistical software and analysis as a function of time and treatment was calculated using t-tests with significance noted at a p<0.05. Results: Gross pathological changes were seen in lung, heart, kidneys, liver and spleen of the triolein group. Pulmonary histological examination revealed diffuse intra-alveolar hemorrhages and edema with peri-bronchial inflammation. Vasculitis was more prominent in the peri-bronchial areas as well. Pulmonary arteries revealed significant medial thickening as compared with the control groups with lumen patency p=0.004. Adventitia/media ratio, with large variability in the triolein group, was not statistically significant. Conclusions: Our data showed that injected triolein remains in the rat lung after 3 and 6 weeks with associated vascular and septal damage in the lung tissue compared to controls. Discussion: This study is a continuation of our previous study showing an increase of severe pulmonary damage within 3-6 hours following triolein induced fat embolism in the rat, reaching a peak at 96 hrs post injection. Despite unmedicated recovery of general condition and body weight and reopening of the pulmonary arteries and arterioles, collagen and vasculitis persisted up to 6 weeks. Further studies are needed to verify the eventual recovery or the organ evolution toward chronic fibrosis

3q26 Amplification is Rarely Present in Women Whose LSIL Cytology does not Represent CIN 2+ Disease

Comparative Medicine - OneHealth and Comparative Medicine Poster SessionObjective: 10-17% of women with LSIL cytology truly have CIN 2+ disease at colposcopically directed biopsy and 20% of the CIN 2+ lesions derive from women with LSIL cytology. No molecular marker has yet been able to triage LSIL cytology effectively. If possible, the triage would spare women the referral to colposcopy. Irreversible chromosomal damage occurs during oncogenesis. Increasing cervical dysplastic severity occurs with increasing amplification of the 3q26 chromosomal region. The purpose of this study is to evaluate the test characteristics of 3q26 amplification in women whose routine cytology is reported as LSIL with emphasis on the negative predictive value for reassurance. Methods: We conducted a retrospective study using the available SurePath™ liquid cytology LSIL archival samples from women 17-59 years old which were linked to colposcopically directed biopsy samples taken on average 36 days after cytology sampling (3-90 day range). Nuclei from the LSIL samples were hybridized with a single-copy probe for the chromosome 3q26 region and a control probe for the centromeric alpha repeat sequence of chromosome 7, using standard FISH methods. Amplification was defined as five or more signals present in at least 2 cells. Results: Of the 68 paired cytology/biopsy samples, 3q26 amplification occurred in 40% of the women with CIN 2+ disease (sensitivity 95% CI: 12, 74). There was no amplification in 91% of women with less than CIN 2 disease (specificity 95% CI: 81, 97); and the negative predictive value was 90% (79, 96). Conclusions: The lack of 3q26 amplification in women with screening cytology LSIL results offers reassurance that CIN 2+ disease has not developed. Future prospective studies are ongoing