Search

Computed tomography angiography (CTA) and magnetic resonance angiography (MRA) are highly accurate cross-sectional vascular imaging modalities that have almost completely replaced diagnostic catheter angiography for the evaluation of the mesenteric vasculature. CTA is the technique of choice when evaluating patients with suspected mesenteric ischemia; it permits to differentiate between occlusive and nonocclusive etiologies, to evaluate indirect signs of bowel ischemia, and in some instances, to provide alternative diagnoses. MRA has the advantage of not using ionizing radiation and iodinated contrast agents and can be appropriate in the nonacute setting. Both CTA and MRA are suitable for the assessment of patients with suspected chronic mesenteric ischemia, allowing to evaluate the degree of atherosclerotic steno-occlusive disease and the existence of collateral circulation, as well as other nonatherosclerotic vascular pathologies such as fibromuscular dysplasia and median arcuate ligament syndrome. CTA provides excellent depiction of visceral aneurysms and has an important role to plan therapy for both occlusive and aneurysmal diseases and in the follow-up of patients after open or endovascular mesenteric revascularization procedures. This article provides an introduction to the CTA and MRA imaging protocol to study the mesenteric vasculature, the imaging findings in patients presenting with acute and chronic mesenteric ischemia and visceral aneurysms, and the value of these imaging techniques for therapy planning and follow-up., (Copyright © 2015 Elsevier Inc. All rights reserved.)

Objectives: The purpose of this study was to test the hypothesis that coronary microvascular function is impaired in subjects with cardiac amyloidosis., Background: Effort angina is common in subjects with cardiac amyloidosis, even in the absence of epicardial coronary artery disease (CAD)., Methods: Thirty-one subjects were prospectively enrolled in this study, including 21 subjects with definite cardiac amyloidosis without epicardial CAD and 10 subjects with hypertensive left ventricular hypertrophy (LVH). All subjects underwent rest and vasodilator stress N-13 ammonia positron emission tomography and 2-dimensional echocardiography. Global left ventricular myocardial blood flow (MBF) was quantified at rest and during peak hyperemia, and coronary flow reserve (CFR) was computed (peak stress MBF/rest MBF) adjusting for rest rate pressure product., Results: Compared with the LVH group, the amyloid group showed lower rest MBF (0.59 ± 0.15 ml/g/min vs. 0.88 ± 0.23 ml/g/min; p = 0.004), stress MBF (0.85 ± 0.29 ml/g/min vs. 1.85 ± 0.45 ml/g/min; p < 0.0001), and CFR (1.19 ± 0.38 vs. 2.23 ± 0.88; p < 0.0001) and higher minimal coronary vascular resistance (111 ± 40 ml/g/min/mm Hg vs. 70 ± 19 ml/g/min/mm Hg; p = 0.004). Of note, almost all subjects with amyloidosis (>95%) had significantly reduced peak stress MBF (<1.3 ml/g/min). In multivariable linear regression analyses, a diagnosis of amyloidosis, increased left ventricular mass, and age were the only independent predictors of impaired coronary vasodilator function., Conclusions: Coronary microvascular dysfunction is highly prevalent in subjects with cardiac amyloidosis, even in the absence of epicardial CAD, and may explain their anginal symptoms. Further study is required to understand whether specific therapy directed at amyloidosis may improve coronary vasomotion in amyloidosis., (Copyright © 2014 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

Purpose: To test the hypothesis that type II endoleak cavity volume (ECV) and endoleak cavity diameter (ECD) measurements are accurate indicators of aneurysm sac volume (ASV) enlargement in patients who undergo endovascular aneurysm repair (EVAR) in the abdominal aorta., Materials and Methods: The institutional review board approved and waived the need to obtain patient consent for this HIPAA-compliant retrospective study. In 72 patients who underwent EVAR, 160 computed tomographic (CT) angiography studies revealed type II endoleaks. Corresponding to these 160 CT angiography studies, 113 CT follow-up studies (in 52 patients) were available and were included in the analysis. ECV measurements were obtained by two observers in consensus by using arterial enhanced phase (ECVAEP) and 70-second delayed enhanced phase (ECVDEP) CT images. The ECVDEP was also normalized as the ECV/ASV ratio. Maximum (ECDM) and transverse (ECDT) ECDs were determined from delayed enhanced phase images. The outcome was determined as interval increase (>2%) in ASV versus stable or decreasing (≤2%) ASV. Receiver operating characteristic (ROC) analysis was used to compare the accuracy of type II ECV and ECD measurements in indicating interval increase in ASV., Results: In 56 (49.5%) of 113 CT studies in type II endoleaks, there was an interval increase in ASV. The accuracies of ECVDEP (area under the ROC curve [AUC], 0.85) and normalized ECVDEP (AUC, 0.86) were superior to the accuracies of ECDM (AUC, 0.73), ECDT (AUC, 0.73), and ECVAEP (AUC, 0.66). At ROC curve analysis, the sensitivity, specificity, and positive and negative predictive values for type II endoleak cavities with an ECVDEP of less than 0.5 mL for showing no future sac volume enlargement were 33% (19 of 57), 100% (56 of 56), 100% (19 of 19), and 60% (56 of 94), respectively., Conclusion: With use of the delayed enhanced phase of CT angiography, ECV measurement is an accurate indicator of aneurysm sac enlargement., (RSNA, 2013)

Although aortic valve replacement is the definitive therapy for severe aortic stenosis, almost half of patients with severe aortic stenosis are unable to undergo conventional aortic valve replacement because of advanced age, comorbidities, or prohibitive surgical risk. Treatment options have been recently expanded with the introduction of catheter-based implantation of a bioprosthetic aortic valve, referred to as transcatheter aortic valve replacement. Because this procedure is characterized by lack of exposure of the operative field, image guidance plays a critical role in preprocedural planning. This guideline document evaluates several preintervention imaging examinations that focus on both imaging at the aortic valve plane and planning in the supravalvular aorta and iliofemoral system. The ACR Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed every 2 years by a multidisciplinary expert panel. The guideline development and review include an extensive analysis of current medical literature from peer-reviewed journals and the application of a well-established consensus methodology (modified Delphi) to rate the appropriateness of imaging and treatment procedures by the panel. In those instances in which evidence is lacking or not definitive, expert opinion may be used to recommend imaging or treatment., (Copyright © 2013 American College of Radiology. Published by Elsevier Inc. All rights reserved.)

Although lead paint was banned by federal law in 1978, it continues to poison children living in homes built before that time. The lifelong effects of childhood exposure to even small amounts of lead are well established by medical research. Federal and state laws have reduced rates of lead poisoning significantly in the past three decades. However, pockets of high rates of lead poisoning remain, primarily in low-income urban neighborhoods with older housing stock. Recently, several municipalities have passed local lead laws to reduce lead hazards in high-risk areas. There has been no systematic attempt to compare the design and effectiveness of these local policies. To address this gap, we conducted comparative case studies of eight innovative lead laws promulgated since 2000. The laws used a wide variety of legal structures and tools, although certain elements were common. The impact of the policies was intertwined with local housing, economic, and legal environments. While data do not yet exist to systematically evaluate the impact of these laws on lead poisoning rates, our analysis suggests that local laws hold great promise for reducing lead hazards in children's homes.

Objective: The purpose of this article is to describe the image acquisition, identification, and reporting of postoperative adhesions in patients undergoing CT for "redo sternotomy" surgical planning., Conclusion: Adhesions appear as linear fibrous bands that join structures in the mediastinum viewed on static images. Confirmation by cine imaging shows deformation of mediastinal structures. Identification and reporting of adhesions will likely guide surgeons to safer interventions.

Aim: The present study evaluated the possibility of drug interactions involving blueberry juice (BBJ) and substrate drugs whose clearance is dependent on cytochromes P4503A (CYP3A) and P4502C9 (CYP2C9)., Methods: A 50:50 mixture of lowbush and highbush BBJ was evaluated in vitro as an inhibitor of CYP3A activity (hydroxylation of triazolam and dealkylation of buspirone) and of CYP2C9 activity (flurbiprofen hydroxylation) using human liver microsomes. In clinical studies, clearance of oral buspirone and oral flurbiprofen was studied in healthy volunteers with and without co-treatment with BBJ., Results: BBJ inhibited CYP3A and CYP2C9 activity in vitro, with 50% inhibitory concentrations (IC50 ) of less than 2%, but without evidence of mechanism-based (irreversible) inhibition. Grapefruit juice (GFJ) also inhibited CYP3A activity, but inhibitory potency was increased by pre-incubation, consistent with mechanism-based inhibition. In clinical studies, GFJ significantly increased area under the plasma concentration-time curve (AUC) for the CYP3A substrate buspirone. The geometric mean ratio (GMR = AUC with GFJ divided by AUC with water) was 2.12. In contrast, the effect of BBJ (GMR = 1.39) was not significant. In the study of flurbiprofen (CYP2C9 substrate), the positive control inhibitor fluconazole significantly increased flurbiprofen AUC (GMR = 1.71), but BBJ had no significant effect (GMR = 1.03)., Conclusion: The increased buspirone AUC associated with BBJ is quantitatively small and could have occurred by chance. BBJ has no effect on flurbiprofen AUC. The studies provide no evidence for concern about clinically important pharmacokinetic drug interactions of BBJ with substrate drugs metabolized by CYP3A or CYP2C9., (© 2012 The Authors. British Journal of Clinical Pharmacology © 2012 The British Pharmacological Society.)

Intraluminal layering of iodinated contrast on a single axial computed tomography image is described as a possible sign of slow arterial flow and is quantified using a new region of interest-based metric, that is, gravitational gradient. The metric was measured in 4 patients who demonstrated this phenomenon and in the aorta of 10 patients with no clinical sign suggestive of slow flow. Future studies are needed to validate the relationship between gravitational gradient, slow flow, and patient outcome.

Aims: Turmeric extract derived curcuminoids (curcumin, demethoxycurcumin and bisdemethoxycurcumin) are currently being evaluated for the treatment of cancer and Alzheimer's dementia. Previous in vitro studies indicate that curcuminoids and piperine (a black pepper derivative that enhances curcuminoid bioavailability) could inhibit human CYP3A, CYP2C9, UGT and SULT dependent drug metabolism. The aim of this study was to determine whether a commercially available curcuminoid/piperine extract alters the pharmacokinetic disposition of probe drugs for these enzymes in human volunteers., Methods: A randomized placebo-controlled six way crossover study was conducted in eight healthy volunteers. A standardized curcuminoid/piperine preparation (4 g curcuminoids plus 24 mg piperine) or matched placebo was given orally four times over 2 days before oral administration of midazolam (CYP3A probe), flurbiprofen (CYP2C9 probe) or paracetamol (acetaminophen) (dual UGT and SULT probe). Plasma and urine concentrations of drugs, metabolites and herbals were measured by HPLC. Subject sedation and electroencephalograph effects were also measured following midazolam dosing., Results: Compared with placebo, the curcuminoid/piperine treatment produced no meaningful changes in plasma C(max), AUC, clearance, elimination half-life or metabolite levels of midazolam, flurbiprofen or paracetamol (α = 0.05, paired t-tests). There was also no effect of curcuminoid/piperine treatment on the pharmacodynamics of midazolam. Although curcuminoid and piperine concentrations were readily measured in plasma following glucuronidase/sulfatase treatment, unconjugated concentrations were consistently below the assay thresholds (0.05-0.08 μM and 0.6 μM, respectively)., Conclusion: The results indicate that short term use of this piperine-enhanced curcuminoid preparation is unlikely to result in a clinically significant interaction involving CYP3A, CYP2C9 or the paracetamol conjugation enzymes., (© 2012 The Authors. British Journal of Clinical Pharmacology © 2012 The British Pharmacological Society.)

Introduction: Since their initial discovery in 1989, grapefruit juice (GFJ)-drug interactions have received extensive interest from the scientific, medical, regulatory and lay communities. Although knowledge regarding the effects of GFJ on drug disposition continues to expand, the list of drugs studied in the clinical setting remains relatively limited., Areas Covered: This article reviews the in vitro effects of GFJ and its constituents on the activity of CYP enzymes, organic anion-transporting polypeptides (OATPs), P-glycoprotein, esterases and sulfotransferases. The translational applicability of the in vitro findings to the clinical setting is discussed for each drug metabolizing enzyme and transporter. Reported AUC ratios for available GFJ-drug interaction studies are also provided. Relevant investigations were identified by searching the PubMed electronic database from 1989 to 2010., Expert Opinion: GFJ increases the bioavailability of some orally administered drugs that are metabolized by CYP3A and normally undergo extensive presystemic extraction. In addition, GFJ can decrease the oral absorption of a few drugs that rely on OATPs in the gastrointestinal tract for their uptake. The number of drugs shown to interact with GFJ in vitro is far greater than the number of clinically relevant GFJ-drug interactions. For the majority of patients, complete avoidance of GFJ is unwarranted.

Recent advances in multidetector-row computed tomography (MDCT) have led to substantial improvements in coverage area, acquisition speed, and temporal/spatial resolution, which have strengthened the performance of thoracic and cardiac MDCT angiography but have also imposed new challenges for optimization of contrast medium enhancement and scan acquisition strategies. Understanding contrast media dynamics is fundamental for the design of scan acquisition and injection protocols. This article examines the fundamentals of the physiological and contrast delivery factors that determine the quality of contrast enhancement, emphasizing the modifications required in contrast delivery protocols for optimizing cardiothoracic MDCT angiography with modern-era MDCT scanners.

Recent advances in multidetector-row computed tomography (MDCT) technology have created new opportunities in cardiac imaging and provided new insights into a variety of disease states. Use of 64-slice coronary computed tomography angiography has been validated for the evaluation of clinically relevant coronary artery stenosis with high negative predictive values for ruling out significant obstructive disease. This technology has also advanced the care of patients with acute chest pain by simultaneous assessment of acute coronary syndrome, pulmonary embolism, and acute aortic syndrome ("triple rule out"). Although MDCT has been instrumental in the advancement of cardiac imaging, there are still limitations in patients with high or irregular heart rates. Newer MDCT scanner generations hold promise to improve some of these limitations for noninvasive cardiac imaging. The evaluation of coronary artery stenosis remains the primary clinical indication for cardiac computed tomography angiography. However, the use of MDCT for simultaneous assessment of coronary artery stenosis, atherosclerotic plaque formation, ventricular function, myocardial perfusion, and viability with a single modality is under intense investigation. Recent technical developments hold promise for accomplishing this goal and establishing MDCT as a comprehensive stand-alone test for integrative imaging of coronary heart disease.

Concerns have been raised regarding the increasing radiation exposure associated with cardiac computed tomography (CT). Traditional cardiac CT imaging techniques comprise simultaneous recording of the electrocardiogram signal combined with continuous slow-pitch spiral/helical scan acquisition with a relatively high incident radiation dose. Because of the increasing number of cardiac CT studies and further anticipated growth, the contribution of cardiac CT to radiation exposure of the population is not negligible. With growing radiation dose awareness, a variety of strategies have been developed aimed at improving the dose efficiency of electrocardiogram-synchronized cardiac CT acquisition techniques. Recent innovations have demonstrated that the radiation dose at cardiac CT can be substantially reduced without detrimental effects on diagnostic image quality. This study reviews currently available strategies for successfully reducing radiation dose in cardiac CT.

Numerous conditions affect the occipitocervical junction requiring treatment with occipitocervical fixation. In this paper the authors present their technique of craniocervical fixation achieved with the cephalad extension of posterior C1-3 polyaxial screw and rods to polyaxial screws placed in the occipital condyles. They retrospectively analyzed occipital condyle morphology obtained from CT analyses of 40 patients with normal cervical spines, evaluated occipital condyle screw placement feasibility in 4 cadavers, and provided a case report of a 70-year-old woman with rheumatoid arthritis, basilar invagination, and atlantoaxial instability who was treated with this novel technique. Based on radiographic analysis of occipital condyle anatomy, they concluded that on average a 3.5-mm-diameter x 20- to 30-mm-long screw can be safely placed at an angle of 20-33 degrees from the sagittal plane. Overall, measuring the condylar heights (mean [+/- SD] 10.8 +/- 1.5 mm, range 8.1-15.0 mm), widths (mean 11.1 +/- 1.4 mm, range 8.5-14.2 mm), lengths (20.3 +/- 2.1 mm, range 15.4-24.6 mm), and angles (mean 32.8 +/- 5.2 degrees , range 20.2-45.8 degrees) by using CT studies is an accurate and precise method. This finding correlates with the results of prior anatomical studies of occipital condyles and is important in the planning of craniovertebral junction surgery.

The prevalence of obesity has dramatically increased in recent years and now includes a significant proportion of the world's children, adolescents and adults. Obesity is linked to a number of co-morbidities, the most prominent being type 2 diabetes mellitus. While many agents are available to treat these conditions, the current knowledge regarding their disposition in the obese remains limited. Over the years, both direct and indirect methodologies have been utilized to assess body composition. Commonly used direct measures include underwater weighing, skinfold measurement, bioelectrical impedance analysis and dual-energy x-ray absorptiometry. Unfortunately, these methods are not readily available to the majority of clinicians. As a result, a number of indirect measures to assess body composition have been developed. Indirect measures rely on patient attributes such as height, bodyweight and sex. These size metrics are often utilized clinically and include body mass index (BMI), body surface area (BSA), ideal bodyweight (IBW), percent IBW, adjusted bodyweight, lean bodyweight (LBW) and predicted normal weight (PNWT). An understanding of how the volume of distribution (V(d)) of a drug changes in the obese is critical, as this parameter determines loading-dose selection. The V(d) of a drug is dependent upon its physiochemical properties, the degree of plasma protein binding and tissue blood flow. Obesity does not appear to have an impact on drug binding to albumin; however, data regarding alpha(1)-acid glycoprotein binding have been contradictory. A reduction in tissue blood flow and alterations in cardiac structure and function have been noted in obese individuals. At the present time, a universal size descriptor to describe the V(d) of all drugs in obese and lean individuals does not exist. Drug clearance (CL) is the primary determinant to consider when designing a maintenance dose regimen. CL is largely controlled by hepatic and renal physiology. In the obese, increases in cytochrome P450 2E1 activity and phase II conjugation activity have been observed. The effects of obesity on renal tubular secretion, tubular reabsorption, and glomerular filtration have not been fully elucidated. As with the V(d), a single, well validated size metric to characterize drug CL in the obese does not currently exist. Therefore, clinicians should apply a weight-normalized maintenance dose, using a size descriptor that corrects for differences in absolute CL between obese and non-obese individuals. The elimination half-life (t((1/2))) of a drug depends on both the V(d) and CL. Since the V(d) and CL are biologically independent entities, changes in the t((1/2)) of a drug in obese individuals can reflect changes in the V(d), the CL, or both. This review also examines recent publications that investigated the disposition of several classes of drugs in the obese--antibacterials, anticoagulants, antidiabetics, anticancer agents and neuromuscular blockers. In conclusion, pharmacokinetic data in obese patients do not exist for the majority of drugs. In situations where such information is available, clinicians should design treatment regimens that account for any significant differences in the CL and V(d) in the obese.

Complications of dacryocystoceles can be life-threatening in neonates. Dacryocystitis is a common complication of dacryocystoceles. The following case report illustrates the clinical characteristics of dacryocystitis in a 4-day-old infant. The pathophysiology, associated anatomical abnormalities, differential diagnosis, complications, and management of dacryocystoceles are reviewed.

Purpose: The use of quetiapine as a drug to treat various substance use disorders as well as a drug of abuse is examined., Summary: Quetiapine's effectiveness in treating schizophrenia and bipolar disorder is well-known; however, growing evidence has indicated that it may be useful in the treatment of various substance use disorders. Small-scale studies have been conducted to investigate the potential benefit of quetiapine in patients dependent on alcohol, cocaine, and amphetamines. The results of these two studies provide some evidence that quetiapine may benefit patients diagnosed with a mental illness who are also dependent on cocaine, amphetamines, or both, though more rigorous studies are needed. An unforeseen use of antipsychotics, specifically quetiapine, as drugs of abuse has emerged. Since antipsychotics are not classified as controlled substances, the majority of clinicians may not consider the diversion of antipsychotics for recreational purposes, but evidence of this is increasing, particularly in incarcerated individuals. Intravenous quetiapine abuse was first reported in the literature in 2005. Although most cases of quetiapine abuse have been reported in the correctional setting, inappropriate quetiapine use within the community has been documented. Thus far, all of the documented cases have involved patients with a prior history of substance abuse. Clinicians must be cognizant of the potential for quetiapine as a treatment for substance use disorders and as a drug of abuse., Conclusion: Quetiapine is a promising treatment for substance use disorders alone or combined with other psychiatric diagnoses, such as bipolar disorder and schizophrenia. Quetiapine abuse has also been documented, particularly in the correctional setting.

Disaster preparedness typically includes plans that address the need for surge capacity to manage mass-casualty events. A major concern of disaster preparedness in respiratory therapy focuses on responding to a sudden increase in the volume of patients who require mechanical ventilation. Plans for such disasters must include contingencies to address surge capacity in ventilator inventories and the respiratory therapy staff who will manage the ventilators. Tactics to address these situations include efforts to lower demand by transferring patients to other institutions as well as efforts to augment staffing levels. Staff can be augmented by mobilization of deployable teams of volunteers from outside the region and through exploitation of local resources. The latter includes strategies to recruit local respiratory therapists who are currently in either non-clinical or non-hospital-based positions and policies that optimize existing respiratory therapy resources within an institution by canceling elective surgeries, altering shift structure, and postponing vacations. An alternative approach would employ non-respiratory-therapy staff to assist in the management of patients with respiratory failure. Project XTREME (Cross-Training Respiratory Extenders for Medical Emergencies) is a cross-training program developed to facilitate training of non-respiratory-therapy health professionals to assist in the management of patients who require mechanical ventilation. It includes an interactive digital video disc as well as a competency validation laboratory and is designed to be performed at the time of an emergency. Pilot testing of the program suggests it is effective.

Studying the structural consequences of the direct binding of arsenite, cadmium, cobalt, nickel, and lead to a number of protein tyrosine kinases led to the discovery of the metal-binding properties of a dicysteine-containing motif in the C-terminal (CT) lobe of the kinases. Of all the synthesized peptides derived from different domains of c-Src and Csk, only peptides based on a dicysteine-containing motif located in the CT lobe of the kinase domain-CPESLHDLMCQC and CPESLHDLMC in c-Src, and CPPAVYDVMKNC in Csk-exhibited significant conformational changes in the presence of all metals, as shown by circular dichroism (CD) analyses. Furthermore, CD analysis of natural enzymes c-Src, Csk, Fyn, c-Abl, Lck, EGFR, and c-Src domains containing the CT lobe in the presence of metals showed a significant concentration-dependent conformational change. ICP-MS, (113)Cd NMR, (33)S NMR, and/or molecular modeling studies of CPESLHDLMC and CPPAVYDVMKNC confirmed the binding between the free sulfhydryl groups of the cysteine residues and Cd(II) or As(III). UV-titration studies suggested a high-affinity interaction between Cd(II) and As(III) and the peptides (K(d) values in the range of 0.6-18.3 nM).

A novel approach is presented for the simultaneous identification and relative quantification of secreted peptides, particularly those that have been historically difficult to analyze in a concerted manner. Peptides exceeding 60 residues with various degrees of post-translational modification were identified on a liquid chromatographic time scale. The approach demonstrates high efficiency pattern-based recognition analysis of complex neuroendocrine peptide sets and enables rapid identification of biomarkers from biological material.

Differential sensitivity (DS) storage dynamics describe a temporal niche axis that determines coexistence of competing taxa through a trade-off between environmental insensitivity and competitive ability at the recruitment stage. In DS storage dynamics, when the relevant environmental factor is low, the more sensitive, better competitor preferentially recruits; when the environmental factor is high, the environmentally sensitive species suffers high mortality and the environmentally insensitive taxon preferentially recruits. A herbivore defense/growth rate trade-off at the seedling/juvenile stage could support this dynamic. We therefore compared juvenile palatability, a measure of anti-herbivore defense, and early growth rate for five congeneric pairs of native British herbs. All five comparisons showed a positive association between average individual growth rate and average palatability to a native slug species. We observed no evidence of associations between early growth rate and adult palatability or between early growth rate and life history strategy (annual vs. perennial). Seed mass was not associated with either early growth rate or with life history strategy whether or not relatedness was taken into account. We offer two explanations as to why we found statistically significant support for a growth rate- defense trade-off when within-species studies so often produce only equivocal results.