Sample-to-answer on molecular diagnosis of bacterial infection using integrated lab--on--a--disc.

Sepsis by bacterial infection causes high mortality in patients in intensive care unit (ICU). Rapid identification of bacterial infection is essential to ensure early appropriate administration of antibiotics to save lives of patients, yet the present benchtop molecular diagnosis is time-consuming and labor-intensive, which limits the treatment efficiency especially when the number of samples to be tested is extensive. Therefore, we hereby report a microfluidic platform lab-on-a-disc (LOAD) to provide a sample-to-answer solution. Our LOAD customized design of microfluidic channels allows automation to mimic sequential analytical steps in benchtop environment. It relies on a simple but controllable centrifugation force for the actuation of samples and reagents. Our LOAD system performs three major functions, namely DNA extraction, isothermal DNA amplification and real-time signal detection, in a predefined sequence. The disc is self-contained for conducting sample heating with chemical lysis buffer and silica microbeads are employed for DNA extraction from clinical specimens. Molecular diagnosis of specific target bacteria DNA sequences is then performed using a real-time loop-mediated isothermal amplification (RT-LAMP) with SYTO-9 as the signal reporter. Our LOAD system capable of bacterial identification of Mycobacterium tuberculosis (TB) and Acinetobacter baumanii (Ab) with the detection limits 103cfu/mL TB in sputum and 102cfu/mL Ab in blood within 2h after sample loading. The reported LOAD based on an integrated approach should address the growing needs for rapid point-of-care medical diagnosis in ICU.

Characterization of carbapenem-resistant Escherichia coli and Klebsiella pneumoniae from a healthcare region in Hong Kong.

Carbapenem-resistant Enterobacteriaceae represents a major public health issue. This study investigated the clonality and resistance mechanisms of 92 carbapenem-resistant E. coli (n = 21) and K. pneumoniae (n = 71) isolates collected consecutively from clinical specimens and patients at high risk of carriage between 2010 and 2012 in a healthcare region in Hong Kong. Combined disk tests (CDTs) and the Carba NP test were used for phenotypic detection of carbapenemases. PCR assays were used to detect carbapenemase genes. All isolates were intermediate or resistant to at least one carbapenem. Nine (9.8 %) isolates were genotypic carbapenemase producers and included six K. pneumoniae (one ST1306/bla IMP-4, one ST889/bla IMP-4, two ST11/bla KPC-2, one ST258/bla KPC-2, one ST483/bla NDM-1) and three E. coli (one ST131/bla IMP-4, two ST744/ bla NDM-1) isolates. All nine isolates carrying carbapenemase genes could be detected by the CDTs and the Carba NP test. PCR identified bla CTX-M and bla AmpC alone or in combination in 77.8 % (7/9) and 96.4 % (80/83) of the carbapenemase-producers and non-producers, respectively. Porin loss was detected in 22.2 % (2/9) and 59.0 % (49/83) of the carbapenemase-producers and non-producers, respectively. Overall, the E. coli clones were diverse (14 different STs), but 36.6 % (26/71) of the K. pneumoniae isolates belonged to ST11. In conclusion, the prevalence of carbapenemases among carbapenem-nonsusceptible E. coli and K. pneumoniae remained low in Hong Kong. Porin loss combined with AmpC and/or CTX-M type ESBL was the major mechanism of carbapenem resistance in the study population.

Total synthesis of (+/-)-asteriscanolide.

The total synthesis of asteriscanolide (1) has been achieved by taking advantage on an intermolecular Pauson-Khand cycloaddition and a ring-closing metathesis as key bond-forming transformations. The approach incorporates the cyclooctane stereogenic center prior to ring formation. Interestingly, the ring-closing metathesis generates a new eight-membered ring with an "in-out" intrabridgehead relationship.

Tear of the peroneus longus tendon: MR imaging features in nine patients.

PURPOSE: To determine the magnetic resonance (MR) imaging features that characterize tear of the peroneus longus tendon at the midfoot. MATERIALS AND METHODS: Medical records and MR images in nine patients with a tear of the middle segment of the peroneus longus tendon were retrospectively reviewed. All nine patients had undergone routine ankle MR imaging; three had undergone additional oblique coronal MR imaging. Surgical proof of a tear was available for three patients. RESULTS: Partial tear was present in four patients, and complete tear was present in five. Partial tears were characterized by heterogeneous signal intensity and thickening of the tendon. Complete tears were characterized by discontinuity of the tendon. Additional findings included fluid in the tendon sheath (n = 6), marrow edema of the lateral calcaneal wall (n = 3), enlarged peroneal tubercle (n = 3), and tear of the peroneus brevis tendon (n = 2). The extent of the tear was better assessed with oblique coronal MR images. CONCLUSION: The characteristic MR imaging appearance of complete or partial tear of the middle portion of the peroneus longus tendon includes foci of increased signal intensity in the distal tendon, morphologic alterations, and/or discontinuity of tendon. Bone marrow edema along the lateral calcaneal wall may be suggestive of the diagnosis. Additional oblique coronal midfoot MR images may help in assessment of the extent of the tear.

MR imaging of flexor digitorum accessorius longus.

OBJECTIVE: The flexor digitorum accessorius longus muscle (FDAL), an anomalous muscle about the ankle, has recently been implicated in tarsal tunnel syndrome. The purpose of this study is to document the prevalence of the FDAL, its MR appearance and its relation to the neurovascular bundle in the tarsal tunnel. DESIGN AND PATIENTS: The prevalence of the FDAL was determined from 100 ankle MR examinations in asymptomatic individuals. The appearance of the FDAL was summarized from 20 examples of FDAL: six gathered from the asymptomatic group and 14 acquired from a group of randomly collected cases of patients with ankle complaints. RESULTS: The prevalence of the FDAL was 6%, calculated from the group of 100 asymptomatic individuals. Possessing a dominant fleshy component in the tarsal tunnel, the FDAL accompanies the posterior neurovascular bundle as it descends the ankle. CONCLUSION: The FDAL is encountered in 6% of asymptomatic individuals. Its prominent fleshy component in the tarsal tunnel and its close proximity to the posterior tibial neurovascular bundle readily differentiate the FDAL from other medial anomalous muscles on MR imaging.

Peroneus quartus muscle: MR imaging features.

PURPOSE: To determine the prevalence of the peroneus quartus (PQ) muscle, to demonstrate the morphology of this accessory muscle on magnetic resonance (MR) images, and to reassess the reported association of the PQ muscle with a hypertrophic peroneal tubercle. MATERIALS AND METHODS: A retrospective review was performed of 136 consecutive ankle MR imaging studies. The origins, insertions, and variations in size of the muscle and the dimensions of the peroneal tubercle and retrotrochlear eminence were recorded. RESULTS: The prevalence of the PQ muscle was 10% (14 of 136 cases). The accessory muscle and tendon unit descended medial and posterior to the peroneal tendons. The site of insertion was variable and included the calcaneus, peroneus longus tendon, peroneus brevis tendon; and cuboid bone. The calcaneus was the insertion site in 11 cases. The accessory tendon attached to the retrotrochlear eminence of the calcaneus. In the group with the PQ muscle, the retrotrochlear eminence was significantly taller (P < .01) than in the group without the PQ muscle. CONCLUSION: Contrary to previous reports, the peroneocalcaneal variant of the PQ muscle appears to insert in the retrotrochlear eminence of the calcaneus rather than the peroneal tubercle. The presence of the PQ muscle is associated with a prominent retrotrochlear eminence but not with an enlarged peroneal tubercle.

MR features of longitudinal tears of the peroneus brevis tendon.

OBJECTIVE: Our objective is to describe the characteristic MR imaging features of longitudinal tears of the peroneus brevis tendon and to describe pathologic conditions and normal variants that are associated with these tears which may require surgical intervention at the time of primary tendon repair. MATERIALS AND METHODS: We retrospectively reviewed 10 MR images of asymptomatic volunteers and 31 MR images of 27 patients with evidence of longitudinal splits of the peroneus brevis tendon. Seven of these cases were surgically proven. In addition, we assessed five pathologic conditions and normal variants: lateral collateral ligamentous tears; injuries to the superior peroneal retinaculum; low-lying muscle belly of the peroneus brevis tendon; peroneus quartus muscle; and convex, flat, or irregular retromalleolar groove. RESULTS: In the patient's group, we saw longitudinal splits as clefts and an irregularity of the contour of the peroneus brevis tendon with (71%) and without (29%) signal changes on proton density-weighted and T2-weighted MR imaging sequences. Divisions of the split tendon assumed a characteristic C-shaped configuration that partly enveloped the peroneus longus tendon. Fifteen cases revealed other pathologic conditions and normal variants known to be associated with or to predispose to tears of the peroneus brevis tendon. These include ankle ligamentous tears (n = 3); abnormal superior peroneal retinaculum (n = 4); low-lying muscle belly of the peroneus brevis tendon (n = 1); peroneus quartus muscle (n = 2); and convex, flat, or irregular retromalleolar groove (n = 15). MR imaging revealed tears in all patients with surgical proof (n = 7). CONCLUSION: MR imaging is a useful technique for revealing longitudinal tears of the peroneus brevis tendon as well as showing anatomic and pathologic factors associated with or predisposed to tears.

Posterior intermalleolar ligament of the ankle: normal anatomy and MR imaging features.

OBJECTIVE: The purposes of this study were to delineate the normal anatomy and MR imaging features of the posterior intermalleolar ligament--a normal ligamentous variant of the posterior portion of the ankle--and to identify normal anatomic characteristics that may account for the role of the ligament in the development of posterior impingement syndrome. MATERIALS AND METHODS: The prevalence, size, and shape of the posterior intermalleolar ligament were documented in 36 cadaveric ankles and in 97 MR studies of the ankle in patients with and without symptoms. RESULTS: The posterior intermalleolar ligament was identified in 20 (56%) of the 36 cadaveric feet. It was 1-8 mm wide, and its diameter (anterior to posterior) was 5-8 mm. The ligament often resembled a meniscus, and in one case its anterior lip herniated into the ankle joint. The posterior intermalleolar ligament was detected in 18 (19%) of the 97 MR studies of the ankle. It was visualized on coronal T1- or T2-weighted images as a distinct, hypointense band traversing between the posterior talofibular ligament and the inferior transverse ligament. CONCLUSION: The posterior intermalleolar ligament is a normal variant of the posterior ligaments of the ankle and is present in a significant number of persons. It is best seen on coronal T1- and T2-weighted MR images. Its meniscuslike shape and occasional extension into the ankle joint may account for the development of posterior impingement syndrome in susceptible persons.

Pseudodefect of the capitellum: potential MR imaging pitfall.

PURPOSE: To describe the pseudodefect of the distal humerus at the junction of the capitellum and lateral epicondyle, which may simulate an osteochondral lesion on axial and coronal magnetic resonance (MR) images. MATERIALS AND METHODS: MR imaging studies of the elbow in 32 patients and 22 asymptomatic volunteers were retrospectively reviewed. Thirty-two human humeri were also examined for normal anatomy of the junction of the capitellum and distal humerus. RESULTS: Twenty-two of the clinical MR examinations and 14 of the studies on volunteers revealed the presence of the pseudodefect. A groove at the junction and the overhanging lateral edges of the capitellum account for the appearance of this pseudolesion. CONCLUSION: Familiarity with the characteristic appearance and location of this pseudodefect will prevent its misinterpretation as an osteochondral fracture of the distal humerus.

The elbow: MR features of nerve disorders.

The authors retrospectively reviewed 15 magnetic resonance (MR) studies of elbows with radiographic evidence of nerve disorders. These 15 cases were selected from 55 MR studies of the elbow in patients referred for various complaints. MR images of the elbow of 10 healthy volunteers were also reviewed. Ulnar nerve disorders were seen in 11 cases. Three patients had median nerve disease, and one patient had a pathologic condition of the radial nerve. The following nerve abnormalities were detected: focal or diffuse nerve thickening, increased signal intensity on T2-weighted images, and course deviation due to either mass effect or spontaneous subluxation. Six of seven patients with nerve thickening, two of two patients with increased nerve signal intensity, and five of eight patients with nerve displacement complained of neurologic symptoms. Four of the patients underwent surgery; in each, surgical results confirmed the findings at MR. These results suggest that MR imaging has a potential role in the detection of nerve disorders at the elbow and in the guidance of treatment.

Osgood-Schlatter lesion: fracture or tendinitis? Scintigraphic, CT, and MR imaging features.

To determine whether the Osgood-Schlatter lesion (OS) is produced by avulsion fracture or injury to the patellar tendon, all images obtained in 28 cases of OS in 20 patients (16 scintigrams, 34 computed tomographic [CT] scans, and 27 magnetic resonance [MR] images) were retrospectively analyzed. In 21 cases, imaging was performed before and after treatment; in 20 cases, relief from pain was complete at the time of repeat examination. In all patients (100%), abnormal size of the tendon, decreased attenuation, and increase in signal intensity were compatible with the CT and MR imaging appearance of tendinitis. Distended deep infrapatellar bursa was a frequent finding, particularly on MR studies. These abnormalities had partially disappeared at follow-up examination. An ossicle was seen in only nine of 28 cases (32%); in three of seven cases with follow-up, the ossicle remained nonunited to the tibial tuberosity on follow-up studies despite relief from symptoms. This implies that healing of fracture is not essential for relief from symptoms. These results strengthen the argument that in most cases of OS, insult to the tendon and associated soft tissues, rather than avulsion fracture, causes OS.

MR findings in extracranial cysticercosis.

A patient with disseminated cysticercosis involving orbit, tongue, parotid glands, epicardial fat, muscle, and subcutaneous tissues is presented. Magnetic resonance findings are described with emphasis on intraorbital and extracranial lesions.