Imaging of pulmonary embolism and t-PA therapy effects using MDCT and liposomal iohexol blood pool agent – preliminary results in a rabbit model

Hypothesis and Objectives PEGylated liposomal blood pool contrast agents maintain contrast enhancement over several hours. This study aimed to evaluate (long-term) imaging of pulmonary arteries, comparing conventional iodinated contrast with a liposomal blood pool contrast agent. Secondly, visualization of the (real-time) therapeutic effects of tissue-Plasminogen Activator (t-PA) on pulmonary embolism (PE) was attempted. Materials and Methods Six rabbits (approximate 4 kg weight) had autologous blood clots injected through the superior vena cava. Imaging was performed using conventional contrast (iohexol, 350 mg I/ml, GE HealthCare, Princeton, NJ) at a dose of 1400 mgI per animal and after wash-out, animals were imaged using an iodinated liposomal blood pool agent (88 mg I/mL, dose 900 mgI/animal). Subsequently, five animals were injected with 2mg t-PA and imaging continued for up to 4 ½ hours. Results Both contrast agents identified PE in the pulmonary trunk and main pulmonary arteries in all rabbits. Liposomal blood pool agent yielded uniform enhancement, which remained relatively constant throughout the experiments. Conventional agents exhibited non uniform opacification and rapid clearance post injection. Three out of six rabbits had mistimed bolus injections, requiring repeat injections. Following t-PA, Pulmonary embolus volume (central to segmental) decreased in four of five treated rabbits (range 10–57%, mean 42%). One animal showed no response to t-PA. Conclusions Liposomal blood pool agents effectively identified acute PE without need for re-injection. PE resolution following t-PA was quantifiable over several hours. Blood pool agents offer the potential for repeated imaging procedures without need for repeated (nephrotoxic) contrast injections

Imaging of pulmonary embolism and t-PA therapy effects using MDCT and liposomal iohexol blood pool agent: preliminary results in a rabbit model.

RATIONALE AND OBJECTIVES: Polyethylene glycol-coated liposomal blood pool contrast agents maintain contrast enhancement over several hours. This study aimed to evaluate (long-term) imaging of pulmonary arteries, comparing conventional iodinated contrast with a liposomal blood pool contrast agent. Also, visualization of the (real-time) therapeutic effects of tissue plasminogen activator (t-PA) on pulmonary embolism (PE) was attempted. MATERIALS AND METHODS: Six rabbits (weight approximately 4 kg) had autologous blood clots injected through the superior vena cava. Imaging was performed using conventional contrast (iohexol, 350 mg I/ml; GE HealthCare, Princeton, NJ) at a dose of 1400 mg I per animal, and after wash-out, animals were imaged using an iodinated liposomal blood pool agent (88 mg I/mL, dose 900 mg I/animal). Subsequently, five animals were injected with 2 mg of t-PA and imaging continued for up to 4(1/2) hours. RESULTS: Both contrast agents identified PE in the pulmonary trunk and main pulmonary arteries in all rabbits. Liposomal blood pool agent yielded uniform enhancement, which remained relatively constant throughout the experiments. Conventional agents exhibited nonuniform opacification and rapid clearance postinjection. Three of six rabbits had mistimed bolus injections, requiring repeat injections. Following t-PA, pulmonary embolus volume (central to segmental) decreased in four of five treated rabbits (range 10-57%, mean 42%). One animal showed no response to t-PA. CONCLUSIONS: Liposomal blood pool agents effectively identified acute PE without need for reinjection. PE resolution following t-PA was quantifiable over several hours. Blood pool agents offer the potential for repeated imaging procedures without need for repeated (nephrotoxic) contrast injections.

Notification of abnormal lab test results in an electronic medical record: do any safety concerns remain?

BACKGROUND: Follow-up of abnormal outpatient laboratory test results is a major patient safety concern. Electronic medical records can potentially address this concern through automated notification. We examined whether automated notifications of abnormal laboratory results (alerts) in an integrated electronic medical record resulted in timely follow-up actions. METHODS: We studied 4 alerts: hemoglobin A1c > or =15%, positive hepatitis C antibody, prostate-specific antigen > or =15 ng/mL, and thyroid-stimulating hormone > or =15 mIU/L. An alert tracking system determined whether the alert was acknowledged (ie, provider clicked on and opened the message) within 2 weeks of transmission; acknowledged alerts were considered read. Within 30 days of result transmission, record review and provider contact determined follow-up actions (eg, patient contact, treatment). Multivariable logistic regression models analyzed predictors for lack of timely follow-up. RESULTS: Between May and December 2008, 78,158 tests (hemoglobin A1c, hepatitis C antibody, thyroid-stimulating hormone, and prostate-specific antigen) were performed, of which 1163 (1.48%) were transmitted as alerts; 10.2% of these (119/1163) were unacknowledged. Timely follow-up was lacking in 79 (6.8%), and was statistically not different for acknowledged and unacknowledged alerts (6.4% vs 10.1%; P =.13). Of 1163 alerts, 202 (17.4%) arose from unnecessarily ordered (redundant) tests. Alerts for a new versus known diagnosis were more likely to lack timely follow-up (odds ratio 7.35; 95% confidence interval, 4.16-12.97), whereas alerts related to redundant tests were less likely to lack timely follow-up (odds ratio 0.24; 95% confidence interval, 0.07-0.84). CONCLUSIONS: Safety concerns related to timely patient follow-up remain despite automated notification of non-life-threatening abnormal laboratory results in the outpatient setting.

Timely follow-up of abnormal diagnostic imaging test results in an outpatient setting: are electronic medical records achieving their potential?

BACKGROUND: Given the fragmentation of outpatient care, timely follow-up of abnormal diagnostic imaging results remains a challenge. We hypothesized that an electronic medical record (EMR) that facilitates the transmission and availability of critical imaging results through either automated notification (alerting) or direct access to the primary report would eliminate this problem. METHODS: We studied critical imaging alert notifications in the outpatient setting of a tertiary care Department of Veterans Affairs facility from November 2007 to June 2008. Tracking software determined whether the alert was acknowledged (ie, health care practitioner/provider [HCP] opened the message for viewing) within 2 weeks of transmission; acknowledged alerts were considered read. We reviewed medical records and contacted HCPs to determine timely follow-up actions (eg, ordering a follow-up test or consultation) within 4 weeks of transmission. Multivariable logistic regression models accounting for clustering effect by HCPs analyzed predictors for 2 outcomes: lack of acknowledgment and lack of timely follow-up. RESULTS: Of 123 638 studies (including radiographs, computed tomographic scans, ultrasonograms, magnetic resonance images, and mammograms), 1196 images (0.97%) generated alerts; 217 (18.1%) of these were unacknowledged. Alerts had a higher risk of being unacknowledged when the ordering HCPs were trainees (odds ratio [OR], 5.58; 95% confidence interval [CI], 2.86-10.89) and when dual-alert (>1 HCP alerted) as opposed to single-alert communication was used (OR, 2.02; 95% CI, 1.22-3.36). Timely follow-up was lacking in 92 (7.7% of all alerts) and was similar for acknowledged and unacknowledged alerts (7.3% vs 9.7%; P = .22). Risk for lack of timely follow-up was higher with dual-alert communication (OR, 1.99; 95% CI, 1.06-3.48) but lower when additional verbal communication was used by the radiologist (OR, 0.12; 95% CI, 0.04-0.38). Nearly all abnormal results lacking timely follow-up at 4 weeks were eventually found to have measurable clinical impact in terms of further diagnostic testing or treatment. CONCLUSIONS: Critical imaging results may not receive timely follow-up actions even when HCPs receive and read results in an advanced, integrated electronic medical record system. A multidisciplinary approach is needed to improve patient safety in this area.

Loss of activator protein-2alpha results in overexpression of the thrombin receptor and correlates with the malignant phenotype of human melanoma

Increasing evidence demonstrates that the thrombin receptor (protease activated receptor-1, PAR-1) plays a major role in tumor invasion and contributes to the metastatic phenotype of human melanoma. We demonstrate that the metastatic potential of human melanoma cells correlates with overexpression of PAR-1. The promoter of the PAR-1 gene contains multiple putative AP-2 and Sp1 consensus elements. We provide evidence that an inverse correlation exists between the expression of AP-2 and the expression of PAR-1 in human melanoma cells. Re-expression of AP-2 in WM266-4 melanoma cells (AP-2 negative) resulted in decreased mRNA and protein expression of PAR-1 and significantly reduced the tumor potential in nude mice. ChIP analysis of the PAR-1 promoter regions bp −365 to −329 (complex 1) and bp −206 to −180 (complex 2) demonstrates that in metastatic cells Sp1 is predominantly binding to the PAR-1 promoter, while in nonmetastatic cells AP-2 is bound. In vitro analysis of complex 1 demonstrates that AP-2 and Sp1 bind to this region in a mutually exclusive manner. Transfection experiments with full-length and progressive deletions of the PAR-1 promoter luciferase constructs demonstrated that metastatic cells had increased promoter activity compared to low and nonmetastatic melanoma cells. Our data shows that exogenous AP-2 expression decreased promoter activity, while transient expression of Sp1 further activated expression of the reporter gene. Mutational analysis of complex 1 within PAR-1 luciferase constructs further demonstrates that the regulation of PAR-1 is mediated through interactions with AP-2 and Sp1. Moreover, loss of AP-2 in metastatic cells alters the AP-2 to Sp1 ratio and DNA-binding activity resulting in overexpression of PAR-1. In addition, we evaluated the expression of AP-2 and PAR-1 utilizing a tissue microarray of 93 melanocytic lesions spanning from benign nevi to melanoma metastasis. We report loss of AP-2 expression in malignant tumors compared to benign tissue while PAR-1 was expressed more often in metastatic melanoma cells than in benign melanocytes. We propose that loss of AP-2 results in increased expression of PAR-1, which in turn results in upregulation of gene products that contribute to the metastatic phenotype of melanoma. ^

Abnormal expression of E2F1 and E2F4 results in hyperproliferation of the ependyma and lethal hydrocephalus

The proliferative role of E2F has been under investigation for several years. However, while it is known that E2F1 and E2F4 play a part in development and differentiation, research has not been centered on determining the exact functions these E2Fs play in brain development, given there high expression levels throughout embryogenesis. A GFAP-E2F1 mouse model directing human E2F1 transgene expression to glial cells, such as ependymal cells, was used in the present study in combination with an E2F4 mutant mouse model. Interestingly, 20% of tgE2F1; E2F4 null mice developed a phenotype consisting of domed head, hunched posture, seizures, tremors, hyperactivity or hypeactivity, dysnea, and low body weight. These mice died during the first three weeks of severe hydrocephalus. Similarly, tgE2F1; E2F4 heterozygous mice also develop severe hydrocephalus, although this occurs at 6 weeks at a 2% frequency. Pathological examination of the brains of those animals uncovered enlarged cerebral ventricles with marked thinning of the cerebral cortices, confirming the diagnosis of three-ventricle hydrocephalus, and the absence of tumors. Careful examination of the aqueduct shows an excess of proliferating cells that may cause a blockage of CSF. Of significance, 44% of ependymal cells in hydrocephalic tgE2F1;E2F4-/- mouse brains were positive for BrdU incorporation. Studies determining the molecular rationale for the hydrocephalic phenotype suggest proliferative ependymal cells may not be exclusively related to dysregulated cell cycle in conjuction with E2F activity. Due in part to the deficiency of E2F4 in this mouse model, we find that differentiation of these ependymal cells is not complete and instead undergoes maturation arrest. This suggestion is confirmed by the expression of genes found in neural stem cells or precursor cell populations, in the ependymal cell region of tgE2F1; E2F4-/-. Therefore, from this study, we conclude that dysregulated E2F1 expression in combination with deficient E2F4 expression results in an undifferentiated ependymal cell population that is hyperproliferative in the ventricular system causing an impediment of CSF circulation. It is further concluded that normal E2F1 and E2F4 expression in brain development is crucial for the proper formation and function of the ventricular system.^

Dysregulation of alternative splicing of coagulation factor V results in bleeding disorder, east Texas type and other disorders of hemostasis

The studies completed herein explore different phenotypes related to the genetic defects that predispose individuals to a disruption of normal hemostasis. In the first study, a novel autosomal dominant bleeding disorder, which is characterized by excessive bleeding with trauma or surgery and menorrhagia in affected women, was studied in a large family (16 affected individuals) from east Texas. Affected members had a prolongation of their PT and/or aPTT, but normal clinical coagulation studies. Previous linkage analysis by Kuang et. al. (2001) mapped the defective gene to 1g23-24 (LODmax 7.22), which contains the gene for coagulation factor V (FV). I identified an alteration (A2440G) in the FV gene in exon 13 that segregated with the disease and was not present in 62 controls. Interestingly, this alteration resulted in a 22-fold up-regulation of a novel alternative splicing variant in patients' RNA versus controls. This translated into a similar fold increase in a 250-kDa isoform of FV seen in patients' plasma versus controls. A recombinant of this splicing event exhibited an increased sensitivity to cleavage by activated protein C (APC) that was more striking in the presence of PS. In addition, this novel isoform had increased APC cofactor activity, thus increasing the degradation of FVIIIa. These data indicated that A2440G up-regulates an alternatively spliced transcript of FV, and increases a FV isoform that hinders coagulation as opposed to promoting it like its wild-type counterpart. ^ The second study reports the largest screening to date of African Americans in two independent cohorts for a rare prothrombin variant, C20209T, which is suspected to be associated with thrombotic disease. The Texas Medical Center Genetics Resource (TexGen) Stroke DNA repository revealed 1.67% (Fisher p=0.27) of African American stroke patients were heterozygous for the 20209*T allele. Screening of the Atherosclerosis Risk in Communities Study (ARIC) cohort (n=3470) for the 20209*T allele revealed a population prevalence of 0.58% in individuals of African American descent; however, all associations with thrombotic disease were negative. Analysis of these two independent cohorts revealed that, unlike its neighbor G20210A, the C20209T variant does not increase the risk of thrombotic events in the African American population. ^

Indeterminate QunatiFERON-TB Gold In-Tube assay results in association with procedural specimen collection in children

BACKGROUND. The development of interferon-gamma release assays (IGRA) has introduced powerful tools in diagnosing latent tuberculosis infection (LTBI) and may play a critical role in the future of tuberculosis diagnosis. However, there have been reports of high indeterminate results in young patient populations (0-18 years). This study investigated results of the QunatiFERON-TB Gold In-Tube (QFT-GIT) IGRA in a population of children (0-18 years) at Texas Children's Hospital in association with specimen collection procedures using surrogate variables. ^ METHODS. A retrospective case-control study design was used for this investigation. Cases were defined as having QFT-GIT indeterminate results. Controls were defined as having either positive or negative results (determinates). Patients' admission status, staff performing specimen collection, and specific nurse performing specimen collection were used as surrogates to measure specimen collection procedures. ^ To minimize potential confounding, abstraction of patients' electronic medical records was performed. Abstracted data included patients' medications and evaluation at the time of QFT-GIT specimen collection in addition to their medical history. QFT-GIT related data was also abstracted. Cases and controls were characterized using chi-squared tests or Fisher's exact tests across categorical variables. Continuous variables were analyzed using one-way ANOVA and t-tests for continuous variables. A multivariate model was constructed by backward stepwise removal of statistically significant variables from univariate analysis. ^ RESULTS. Patient data was abstracted from 182 individuals aged 0-18 years from July 2010 to August 2011 at Texas Children's Hospital. 56 cases (indeterminates) and 126 controls (determinates) were enrolled. Cancer was found to be an effect modifier with subsequent stratification resulting in a cancer patient population too small to analyze (n=13). Subsequent analyses excluded these patients. ^ The exclusion of cancer patients resulted in a population of 169 patients with 49 indeterminates (28.99%) and 120 determinates (71.01%), with mean ages of 9.73 (95% CI: 8.03, 11.43) years and 11.66 (95% CI: 10.75, 12.56) years (p = 0.033), respectively. Median age of patients who were indeterminates and determinates were 12.37 and 12.87 years, respectively. Lack of data for our specific nurse surrogate (QFTNurse) resulted in its exclusion from analysis. The final model included only our remaining surrogate variables (QFTStaff and QFTInpatientOutpatient). The staff collecting surrogate (QFTStaff) was found to be modestly associated with indeterminates when nurses collected the specimen (OR = 1.54, 95% CI: 0.51, 4.64, p = 0.439) in the final model. Inpatients were found to have a strong and statistically significant association with indeterminates (OR = 11.65, 95% CI: 3.89, 34.9, p < 0.001) in the final model. ^ CONCLUSION. Inpatient status was used as a surrogate for indication of nurse drawn blood specimens. Nurses have had little to no training regarding shaking of tubes versus phlebotomists regarding QFT-GIT testing procedures. This was also measured by two other surrogates; specifically a medical note stating whether a nurse or phlebotomist collected the specimen (QFTStaff) and the name and title of the specific nurse if collection was performed by a nurse (QFTNurse). Results indicated that inpatient status was a strong and statistically significant factor for indeterminates, however, nurse collected specimens and indeterminate results had no statistically significant association in non-cancer patients. The lack of data denoting the specific nurse performing specimen collection excluded the QFTNurse surrogate in our analysis. ^ Findings suggests training of staff personnel in specimen procedures may have little effect on the number of indeterminates while inpatient status and thus possibly illness severity may be the most important factor for indeterminate results in this population. The lack of congruence between our surrogate measures may imply that our inpatient surrogate gauged illness severity rather than collection procedures as intended. ^ Despite the lack of clear findings, our analysis indicated that more than half of indeterminates were found in specimens drawn by nurses and as such staff training may be explored. Future studies may explore methods in measuring modifiable variables during pre-analytical QFT-GIT procedures that can be discerned and controlled. Identification of such measures may provide insight into ways to lowering indeterminate QFT-GIT rates in children.^

Cervical cancer screening in Hispanic women as compared with other ethnic groups on an urban campus

Although Pap screening has decreased morbidity and mortality from cervical cancer, reported statistics indicate that among ethnic groups, Hispanic women are one of the least likely to follow screening guidelines. Human papillomavirus (HPV), a major risk factor for cervical cancer, as well as pre-cancerous lesions, may be detected by early Pap screening. With a reported 43% prevalence of HPV infection in college women, regular Pap screening is important. The purpose of this descriptive, cross-sectional survey was to examine self-reported cervical cancer screening rates in a target population of primarily Mexican-American college women, and to discover if recognized correlates for screening behavior explained differences in screening rates between this and two other predominant groups on the University of Houston Downtown campus, non-Hispanic white and African-American. The sample size consisted of 613 women recruited from summer 2003 classes. A survey, adapted from an earlier El Paso study, and based on constructs of the Health Belief Model (HBM), was administered to women ages 18 and older. It was found that although screening rates were similar across ethnic groups, overall, the Hispanic group obtained screening less frequently, though this did not reach statistical significance. However, a significant difference in lower screening rates was found in Mexican American women ages <25. Additionally, of the predicted correlates, the construct of perceived barriers from the HBM was most significant for the Mexican American group for non-screening. For all groups, knowledge about cervical cancer was negatively correlated with ever obtaining Pap screening and screening within the past year. This implies that if health counseling is given at the time of women's screening visits, both adherence to appropriate screening intervals and risk factor avoidance may be more likely. Studies such as these are needed to address both screening behaviors and likelihood of follow-up for abnormal results in populations of multicultural, urban college women. ^

Are anatomic brain locations important in determining the clinical outcomes in acute ischemic stroke? --- An exploratory analysis of the NINDS Stroke Trial data

Background and purpose. Brain lesions in acute ischemic stroke measured by imaging tools provide important clinical information for diagnosis and final infarct volume has been considered as a potential surrogate marker for clinical outcomes. Strong correlations have been found between lesion volume and clinical outcomes in the NINDS t-PA Stroke Trial but little has been published about lesion location and clinical outcomes. Studies of the National Institute of Neurological Disorders and Stroke (NINDS) t-PA Stroke Trial data found the direction of the t-PA treatment effect on a decrease in CT lesion volume was consistent with the observed clinical effects at 3 months, but measure of t-PA treatment benefits using CT lesion volumes showed a diminished statistical significance, as compared to using clinical scales. ^ Methods. We used the global test to evaluate the hypothesis that lesion locations were strongly associated with clinical outcomes within each treatment group at 3 months after stroke. The anatomic locations of CT scans were used for analysis. We also assessed the effect of t-PA on lesion location using a global statistical test. ^ Results. In the t-PA group, patients with frontal lesions had larger infarct volumes and worse NIHSS score at 3 months after stroke. The clinical status of patients with frontal lesions in t-PA group was less likely to be affected by lesion volume, as compared to those who had no frontal lesions in at 3 months. For patients within the placebo group, both brain stem and internal capsule locations were significantly associated with a lower odd of having favorable outcomes at 3 months. Using a global test we could not detect a significant effect of t-PA treatment on lesion location although differences between two treatment groups in the proportion of lesion findings in each location were found. ^ Conclusions. Frontal, brain stem, and internal capsule locations were significantly related to clinical status at 3 months after stroke onset. We detect no significant t-PA effect on all 9 locations although proportion of lesion findings in differed among locations between the two treatment groups.^