CT in the evaluation of nontraumatic abdominal pain in pregnant women

PURPOSE: To retrospectively determine sensitivity and specificity of computed tomography (CT) for the diagnosis of appendicitis in pregnant women with nontraumatic abdominal pain and retrospectively compare findings at CT and ultrasonography (US) in patients who underwent both examinations, with surgery or clinical follow-up as a reference standard. MATERIALS AND METHODS: Institutional review board approval was obtained, and the study was HIPAA compliant. Informed consent was waived. Findings of 80 consecutive CT examinations performed in 78 pregnant women (mean age, 25.9 years; range, 17-43 years) for abdominal pain between September 2000 and October 2004 were compared with findings at prior US (n=52), surgery, and clinical follow-up. Sensitivity and specificity were calculated for the diagnosis of appendicitis. The average fetal radiation dose was 16 mGy (1.6 rad) (range, 4-45 mGy [4-4.5 rad]). RESULTS: CT findings were normal in 51 examinations (64%) and abnormal in 29 (36%). Abnormal findings were appendicitis (n=13), urinary tract calculi (n=6), small-bowel obstruction (n=2), cholelithiasis (n=2), pyelonephritis (n=2), diaphragmatic hernia (n=1), cecal bascule (n=1), ileus (n=1), and metastatic lymphadenopathy (n=1). One surgically confirmed case of appendicitis was not detected at CT. For diagnosis of appendicitis, sensitivity of CT was 92% (12 of 13 examinations), specificity was 99% (66 of 67), and negative predictive value was 99% (66 of 67). Fifty-two CT studies were performed after US. US findings were normal in 46 patients (88%) and abnormal in six (12%). Abnormal findings were cholelithiasis (n=3), obstructive hydronephrosis (n=1), small-bowel dilatation (n=1), and appendicitis (n=1). Among 46 patients with normal US findings, CT findings were abnormal in 14, nine of whom required surgery. CT added important diagnostic information in 14 of 46 patients (30%). CONCLUSION: CT findings established the diagnosis in 35% of examinations in pregnant women with abdominal pain (28 of 80), with a negative predictive value of 99% for appendicitis; when CT followed negative US findings, CT findings established the diagnosis in 30% of patients.     

Four-dimensional vascular tree reconstruction using moving grid deformation

RATIONALE AND OBJECTIVES: Thinned perforator flaps have been widely used in plastic surgery for greater survivability and decreased morbidity. However, quantitative analysis of three-dimensional (3D) blood flow direction and location has not been examined yet. Such information will benefit and guide the surgical thinning and dissection process. Toward this goal, this study was performed for 3D vascular tree reconstruction with the incorporation of temporal contrast-agent propagation information (three spatial dimensions plus one temporal dimension; ie, 4D). MATERIALS AND METHODS: A novel computational framework by adopting a moving grid deformation method is presented. To take advantage of temporal information of the bolus propagating, a sequential segmentation procedure is proposed. Moreover, the temporal evolution of the vascular tree (4D vascular tree) is reconstructed during the procedure. RESULTS: Eight anterolateral thigh perforator flaps from eight cadavers were used for this study. The age range is 60-80 years old and the gender includes four males and four females. The 3D nature of the vascular structure and 4D vascular tree evolving process are showed in comparison with maximum intensity projection images. CONCLUSION: The proposed computational framework demonstrates effectiveness in the modeling of 4D vascular tree. Furthermore, it reveals the ability to detect small vessel tree structures that are beyond the limit of image resolution.     

Radiation exposure from diagnostic imaging in severely injured trauma patients

BACKGROUND: Trauma patients often require multiple imaging tests, including computed tomography (CT) scans. CT scanning, however, is associated with high-radiation doses. The purpose of this study was to measure the radiation doses trauma patients receive from diagnostic imaging. METHODS: A prospective cohort study was conducted from June 1, 2004 to March 31, 2005 at a Level I trauma center in Toronto, Canada. All trauma patients who arrived directly from the scene of injury and who survived to discharge were included. Three dosimeters were placed on each patient (neck, chest, and groin) before radiologic examination. Dosimeters were removed before discharge. Surface doses in millisieverts (mSv) at the neck, chest, and groin were measured. Total effective dose, thyroid, breast, and red bone marrow organ doses were then calculated. RESULTS: Trauma patients received a mean effective dose of 22.7 mSv. The standard "linear no threshold" (LNT) model used to extrapolate from effects observed at higher dose levels suggests that this would result in approximately 190 additional cancer deaths in a population of 100,000 individuals so exposed. In addition, the thyroid received a mean dose of 58.5 mSv. Therefore, 4.4 additional fatal thyroid cancers would be expected per 100,000 persons. In all, 22% of all patients had a thyroid dose of over 100 mSv (mean, 156.3 mSv), meaning 11.7 additional fatal thyroid cancers per 100,000 persons would result in this subgroup. CONCLUSION: Trauma patients are exposed to significant radiation doses from diagnostic imaging, resulting in a small but measurable excess cancer risk. This small individual risk may become a greater public health issue as more CT examinations are performed. Unnecessary CT scans should be avoided.     

Regulation of autophagy by reactive oxygen species (ROS): implications for cancer progression and treatment

Reactive oxygen species (ROS) have been identified as signaling molecules in various pathways regulating both cell survival and cell death. Autophagy, a self-digestion process that degrades intracellular structures in response to stress, such as nutrient starvation, is also involved in both cell survival and cell death. Alterations in both ROS and autophagy regulation contribute to cancer initiation and progression, and both are targets for developing therapies to induce cell death selectively in cancer cells. Many stimuli that induce ROS generation also induce autophagy, including nutrient starvation, mitochondrial toxins, hypoxia, and oxidative stress. Some of these stimuli are under clinical investigation as cancer treatments, such as 2-methoxyestrodial and arsenic trioxide. Recently, it was demonstrated that ROS can induce autophagy through several distinct mechanisms involving Atg4, catalase, and the mitochondrial electron transport chain (mETC). This leads to both cell-survival and cell-death responses and could be selective toward cancer cells. In this review, we give an overview of the roles ROS and autophagy play in cell survival and cell death, and their importance to cancer. Furthermore, we describe how autophagy is mediated by ROS and the implications of this regulation to cancer treatments.     

Rapid detection of the CYP2A6*12 hybrid allele by Pyrosequencing? technology

Background  

Identification of CYP2A6 alleles associated with reduced enzyme activity is important in the study of inter-individual differences in drug metabolism. CYP2A6*12 is a hybrid allele that results from unequal crossover between CYP2A6 and CYP2A7 genes. The 5' regulatory region and exons 1–2 are derived from CYP2A7, and exons 3–9 are derived from CYP2A6. Conventional methods for detection of CYP2A6*12 consist of two-step PCR protocols that are laborious and unsuitable for high-throughput genotyping. We developed a rapid and accurate method to detect the CYP2A6*12 allele by Pyrosequencing technology.     

Postprandial lipemia as an early predictor of cardiovascular complications in childhood obesity

Abstract. The growing trend of childhood overweight and obesity is a major health concern worldwide. Although obesity is a key risk factor for cardiovascular disease, the etiologic link between obesity and the progression of vascular disease remains unknown. Traditionally, lowering fasting blood cholesterol concentration has been the main interventional target for decreasing the risk of heart disease. However, there is increasing evidence that elevated concentrations of intestinally-derived chylomicron particles are associated with cardiovascular disease risk and that this is particularly evident in insulin-resistance and obesity in adulthood. In this review we comment on recent evidence suggesting that overweight children have fasting chylomicron concentrations equivalent to that found in adults diagnosed with cardiovascular disease. Further, we consider the hypothesis that fasting and postprandial chylomicron metabolism has a central role in the genesis of cardiovascular disease during childhood obesity.     

Sequence learning is preserved in individuals with cerebellar degeneration when the movements are directly cued

Cerebellar pathology is associated with impairments on a range of motor learning tasks including sequence learning. However, various lines of evidence are at odds with the idea that the cerebellum plays a central role in the associative processes underlying sequence learning. Behavioral studies indicate that sequence learning, at least with short periods of practice, involves the establishment of effector-independent, abstract spatial associations, a form of representation not associated with cerebellar function. Moreover, neuroimaging studies have failed to identify learning-related changes within the cerebellum. We hypothesize that the cerebellar contribution to sequence learning may be indirect, related to the maintenance of stimulus-response associations in working memory, rather than through processes directly involved in the formation of sequential predictions. Consistent with this hypothesis, individuals with cerebellar pathology were impaired in learning movement sequences when the task involved a demanding stimulus-response translation. When this translation process was eliminated by having the stimuli directly indicate the response location, the cerebellar ataxia group demonstrated normal sequence learning. This dissociation provides an important constraint on the functional domain of the cerebellum in motor learning.