Imaging Fibrogenesis in a Diet-Induced Model of Nonalcoholic Steatohepatitis (NASH).

Purpose: Liver fibrosis is the hallmark of chronic nonalcoholic steatohepatitis (NASH) and is characterised by the excessive deposition of extracellular matrix proteins. Early detection and accurate staging of liver fibrosis is critically important for patient management. One of the earliest pathological markers in NASH is the activation of hepatic stellate cells (HSCs) which may be exploited as a marker of fibrogenesis. Activated HSCs secreting factors such as integrin α v ß 3 propagate fibrosis. The purpose of the current study was to assess the utility of the integrin α v ß 3 imaging agent [18F]FtRGD for the early detection of fibrosis in a diet-induced model of NASH longitudinally using PET imaging. Procedures: Mice were fed with either standard chow diet (SD), high-fat diet (HFD), or a choline-deficient, L-amino acid-defined high-fat fibrogenic diet (CDAHFD) to mimic the clinical pathology of liver disease and followed longitudinally for 10 weeks to assess the development of liver fibrosis using [18F]FtRGD positron emission tomography (PET) imaging. Standard blood biochemistry, histological measures, and qPCR were used to quantify integrin α v ß 3, smooth muscle actin, and collagen types 1 and 6 to assess the extent of NASH pathology and accurately stage liver fibrosis. Results: The CDAHFD fibrogenic diet predictably developed hepatic inflammation and steatosis over the 10 weeks studied with little NASH pathology detected in high fat diet-treated animals. Stage 1 fibrosis was detected early by histology at day 21 and progressed to stage 2 by day 35 and stage 3 by day 56 in mice fed with CDAHFD diet only. Noninvasive imaging with [18F]FtRGD correlated well with integrin α v ß 3 and was able to distinguish early mild stage 2 fibrosis in CDAHFD animals compared with standard chow diet-fed animals at day 35. When compared with high fat diet-fed animals, [18F]FtRGD was only able to distinguish later moderate stage 2 fibrosis in CDAHFD animals at day 49. Conclusions: The diet-induced progression of liver fibrosis was confirmed using histology and correlated well with the mRNA of integrin α v ß 3 and extracellular matrix protein expression. [18F]FtRGD showed very good correlation between liver uptake and integrin α v ß 3 expression and similar detection sensitivity to the current clinical gold standard modalities for staging of liver fibrosis.

Imaging adipose tissue browning using the TSPO-18kDa tracer [18F]FEPPA.

OBJECTIVES: The browning of white adipose tissue (WAT) into beige has been proposed as a strategy to enhance energy expenditure to combat the growing epidemic of obesity. Research into browning strategies are hampered by the lack of sensitive, translatable, imaging tools capable of detecting beige fat mass non-invasively. [18F]FDG is able to detect activated beige fat but provides little information on unstimulated beige fat mass. We have assessed the use of [18F]FEPPA, a tracer for the TSPO-18KDa found on the outer mitochondrial membrane, as an alternative imaging agent capable of detecting unstimulated brown fat (BAT) and beige fat. METHODS: Female Balb/c mice (n = 5) were treated for 7 days with the ß3 adrenergic agonist CL-316,243 to induce the browning of inguinal WAT (beige fat). Animals were imaged longitudinally with [18F]FDG and [18F]FEPPA and uptake in interscapular BAT and inguinal WAT assessed. The browning of inguinal WAT was confirmed using H&E and immunohistochemical detection of UCP-1 and TSPO. RESULTS: Repeated dosing with ß3-adrenergic agonist CL-316,243 caused a significant increase in [18F]FDG uptake in both interscapular BAT and inguinal WAT associated with the increased metabolic activity of brown and beige adipocytes respectively. [18F]FEPPA uptake was likewise increased in inguinal WAT but showed no increase in BAT uptake due to stimulation over the same time course. Furthermore, inguinal WAT uptake was unaffected by pharmacological blockade, indicating that [18F]FEPPA uptake is associated with the expression of mitochondria in BAT and beige adipocytes and independent of activation. CONCLUSION: These data show that [18F]FEPPA can detect BAT and newly formed beige fat under non-stimulated, thermoneutral conditions and that uptake after stimulation is linked to mitochondrial expression as opposed to activation.

Discrepancy in blood pressure between the left and right arms - importance of clinical diagnosis and role of radiological imaging.

INTRODUCTION: Differences in systolic blood pressure reading between arms are common but could signal trouble if the discrepancy is significant. Early detection of aortic dissection could invariably determine patient's survivability. Hence, a high index of suspicion with prompt diagnostic imaging is vital for accurate diagnosis. CASE PRESENTATION: A previously healthy 35-year-old lady was referred from district hospital for hypertensive cardiomyopathy complicated by acute pulmonary oedema. After being admitted to the Intensive Care Unit, the mean arterial pressure on the left arm was noted to be significant higher. On physical examination, both lower limbs were dusky in appearance because of poor perfusion. INVESTIGATIONS: Computed Tomography Angiography showed extensive arch and abdominal aorta dissection extending to the proximal common carotid artery. There was distal abdominal aorta thrombosis with partial left renal infarction. Echocardiogram showed global hypokinesia, presence of intimal flap, aortic regurgitation and mild pericardial effusion. Supine chest X-ray showed apparent cardiomegaly. TREATMENT: Repair of the ascending aortic dissection and suspension of the aortic valve by the cardiothoracic team on Day 2 of admission. The vascular team did bilateral high above knee amputation on Day 9 of admission. OUTCOME: Patient passed away on Day 10 of admission. DISCUSSION: With the absence of classical features of aortic dissection, establishing the diagnosis can be challenging and requires both good clinical judgment and prompt radiological imaging, such that early treatment can be initiated. CONCLUSION: A high index of suspicion and good clinical judgment is needed in cases of significant blood pressure discrepancy between arms.

Ping wei san, a Chinese medicine for gastrointestinal disorders.

OBJECTIVE: To describe the dilemma that American pharmacists face when their patient uses a traditional Chinese herbal formula. Ping wei san (PWS), an agent used to treat gastrointestinal disorders, is used to illustrate the problems encountered and to identify resources on Chinese herbal medicines available to pharmacists. DATA SYNTHESIS: In the US, Chinese herbal medicine is making its way into mainstream Western medicine. Patients may discover PWS in their search for a substitute for cisapride, which was partially withdrawn from the US market in July 2000. The pharmacist may be called on to assist in the management of patients who wish to use PWS for treatment of common gastrointestinal disorders like gastritis, esophageal reflux, gastric or duodenal ulcers, and acute or chronic enteritis. As with most other Chinese herbal formulas, English-language literature about PWS is limited and is often difficult to interpret. Pharmacists who are unfamiliar with the basic principles and terminology used in traditional Chinese medical practices will need to identify sources of information about this complementary alternative practice to be able to provide pharmaceutical care for patients taking a Chinese herbal formula like PWS. CONCLUSIONS: To develop a pharmaceutical care plan for patients using a Chinese herbal medicine therapy such as PWS, the pharmacist will need to become familiar with traditional Chinese medical practices and terminology describing indications, therapeutic effects, and risks. Fortunately, resources are available to pharmacists who need assistance in interpreting information on Chinese herbal therapies so that they can appropriately manage patients using them.