Structural and functional relationships in the virulence-associated cathepsin L proteases of the parasitic liver fluke, Fasciola hepatica

The helminth parasite Fasciola hepatica secretes cysteine proteases to facilitate tissue invasion, migration, and development within the mammalian host. The major proteases cathepsin L1 (FheCL1) and cathepsin L2 (FheCL2) were recombinantly produced and biochemically characterized. By using site-directed mutagenesis, we show that residues at position 67 and 205, which lie within the S2 pocket of the active site, are critical in determining the substrate and inhibitor specificity. FheCL1 exhibits a broader specificity and a higher substrate turnover rate compared with FheCL2. However, FheCL2 can efficiently cleave substrates with a Pro in the P2 position and degrade collagen within the triple helices at physiological pH, an activity that among cysteine proteases has only been reported forhuman cathepsin K. The 1.4-Å three-dimensional structure of the FheCL1 was determined by x-ray crystallography, and the three-dimensional structure of FheCL2 was constructed via homology-based modeling. Analysis and comparison of these structures and our biochemical data with those of human cathepsins L and Kprovided an interpretation of the substrate-recognition mechanisms of these major parasite proteases. Furthermore, our studies suggest that a configuration involving residue 67 and the "gatekeeper" residues 157 and 158 situated at the entrance of the active site pocket create a topology that endows FheCL2 with its unusual collagenolytic activity. The emergence of a specialized collagenolytic function in Fasciola likely contributes to the success of this tissue-invasive parasite. © 2008 by The American Society for Biochemistry and Molecular Biology, Inc

Complications Associated with the Percutaneous Insertion of Fiducial Markers in the Thorax

Radiosurgery requires precise lesion localization. Fiducial markers enable lesion tracking, but complications from insertion may occur. The purpose of this study was to describe complications of fiducial marker insertion into pulmonary lesions. Clinical and imaging records of 28 consecutive patients with 32 lung nodules or masses who underwent insertion of a total of 59 fiducial markers before radiosurgery were retrospectively reviewed. Eighteen patients (67%) developed a pneumothorax, and six patients (22%) required a chest tube. The rates of pneumothorax were 82% and 40%, respectively, when 18-gauge and 19-gauge needles were used for marker insertion (P = 0.01). Increased rate of pneumothorax was also associated with targeting smaller lesions (P = 0.03) and tumors not in contact with the pleural surface (P = 0.04). A total of 11 fiducials (19%) migrated after insertion into the pleural space (10 markers) or into the airway (1 marker). Migration was associated with shorter distances from pleura to the marker deposition site (P = 0.04) and with fiducial placement outside of the target lesion (P = 0.03). Fiducial marker placement into lung lesions is associated with a high risk of pneumothorax and a risk of fiducial migration

Reducing Constraints in a Higher Dimensional Extension of the Randall and Sundrum Model

In order to investigate the phenomenological implications of warped spaces in more than five dimensions, we consider a $4+1+\delta$ dimensional extension to the Randall and Sundrum model in which the space is warped with respect to a single direction by the presence of an anisotropic bulk cosmological constant. The Einstein equations are solved, giving rise to a range of possible spaces in which the $\delta$ additional spaces are warped. Here we consider models in which the gauge fields are free to propagate into such spaces. After carrying out the Kaluza Klein (KK) decomposition of such fields it is found that the KK mass spectrum changes significantly depending on how the $\delta$ additional dimensions are warped. We proceed to compute the lower bound on the KK mass scale from electroweak observables for models with a bulk $SU(2)\times U(1)$ gauge symmetry and models with a bulk $SU(2)_R\times SU(2)_L\times U(1)$ gauge symmetry. It is found that in both cases the most favourable bounds are approximately $M_{KK}\gtrsim 2$ TeV, corresponding to a mass of the first gauge boson excitation of about 4-6 TeV. Hence additional warped dimensions offer a new way of reducing the constraints on the KK scale.Comment: 27 pages, 15 figures, v3: Additional comments in sections 1, 2 and 4. New appendix added. Five additional figures. References adde

Comparison of m-mode echocardiographic left ventricular mass measured using digital and strip chart readings: The Atherosclerosis Risk in Communities (ARIC) study

BACKGROUND: Epidemiological and clinical studies frequently use echocardiography to measure LV wall thicknesses and chamber dimension for estimating quantitative measures of LV mass. While echocardiographic M-mode LV images have traditionally been measured using hand-held calipers and strip-chart paper tracings, digitized M-mode LV image measurements made directly on the computer screen using electronic calipers have become standard practice. We sought to determine if systematic differences in LV mass occur between the two methods by comparing LV mass measured from simultaneous M-mode strip chart recordings and digitized recordings. METHODS: The Atherosclerosis Risk in Communities study applied the latter method. To determine if systematic differences in LV mass occur between the two methods, LV mass was measured from simultaneous M-mode strip chart recordings and digitized recordings. RESULTS: We found no difference in LV mass (p > .25) and a strong correlation in LV mass between the two methods (r = 0.97). Neither age, sex, nor hypertension status affected the correlation of LV mass between the two methods. CONCLUSIONS: We conclude that digital estimates of LV mass provide unbiased estimates comparable to the strip-chart method

A highly attenuated recombinant human respiratory syncytial virus lacking the G protein induces long-lasting protection in cotton rats

<p>Abstract</p> <p>Background</p> <p>Respiratory syncytial virus (RSV) is a primary cause of serious lower respiratory tract illness for which there is still no safe and effective vaccine available. Using reverse genetics, recombinant (r)RSV and an rRSV lacking the G gene (ΔG) were constructed based on a clinical RSV isolate (strain 98-25147-X).</p> <p>Results</p> <p>Growth of both recombinant viruses was equivalent to that of wild type virus in Vero cells, but was reduced in human epithelial cells like Hep-2. Replication in cotton rat lungs could not be detected for ΔG, while rRSV was 100-fold attenuated compared to wild type virus. Upon single dose intranasal administration in cotton rats, both recombinant viruses developed high levels of neutralizing antibodies and conferred comparable long-lasting protection against RSV challenge; protection against replication in the lungs lasted at least 147 days and protection against pulmonary inflammation lasted at least 75 days.</p> <p>Conclusion</p> <p>Collectively, the data indicate that a single dose immunization with the highly attenuated ΔG as well as the attenuated rRSV conferred long term protection in the cotton rat against subsequent RSV challenge, without inducing vaccine enhanced pathology. Since ΔG is not likely to revert to a less attenuated phenotype, we plan to evaluate this deletion mutant further and to investigate its potential as a vaccine candidate against RSV infection.</p

Characterizing the double-sided cascade of care for adolescents living with HIV transitioning to adulthood across Southern Africa

INTRODUCTION: As adolescents and young people living with HIV (AYLH) age, they face a "transition cascade," a series of steps associated with transitions in their care as they become responsible for their own healthcare. In high-income countries, this usually includes transfer from predominantly paediatric/adolescent to adult clinics. In sub-Saharan Africa, paediatric HIV care is mostly provided in decentralized, non-specialist primary care clinics, where "transition" may not necessarily include transfer of care but entails becoming more autonomous for one's HIV care. Using different age thresholds as proxies for when "transition" to autonomy might occur, we evaluated pre- and post-transition outcomes among AYLH. METHODS: We included AYLH aged <16 years at enrolment, receiving antiretroviral therapy (ART) within International epidemiology Databases to Evaluate AIDS Southern Africa (IeDEA-SA) sites (2004 to 2017) with no history of transferring care. Using the ages of 16, 18, 20 and 22 years as proxies for "transition to autonomy," we compared the outcomes: no gap in care (≥2 clinic visits) and viral suppression (HIV-RNA <400 copies/mL) in the 12 months before and after each age threshold. Using log-binomial regression, we examined factors associated with no gap in care (retention) in the 12 months post-transition. RESULTS: A total of 5516 AYLH from 16 sites were included at "transition" age 16 (transition-16y), 3864 at 18 (transition-18y), 1463 at 20 (transition-20y) and 440 at 22 years (transition-22y). At transition-18y, in the 12 months pre- and post-transition, 83% versus 74% of AYLH had no gap in care (difference 9.3 (95% confidence interval (CI) 7.8 to 10.9)); while 65% versus 62% were virally suppressed (difference 2.7 (-1.0 to 6.5%)). The strongest predictor of being retained post-transition was having no gap in the preceding year, across all transition age thresholds (transition-16y: adjusted risk ratio (aRR) 1.72; 95% CI (1.60 to 1.86); transition-18y: aRR 1.76 (1.61 to 1.92); transition-20y: aRR 1.75 (1.53 to 2.01); transition-22y: aRR 1.47; (1.21 to 1.78)). CONCLUSIONS: AYLH with gaps in care need targeted support to prevent non-retention as they take on greater responsibility for their healthcare. Interventions to increase virologic suppression rates are necessary for all AYLH ageing to adulthood

Imaging-guided chest biopsies: techniques and clinical results

Background This article aims to comprehensively describe indications, contraindications, technical aspects, diagnostic accuracy and complications of percutaneous lung biopsy. Methods Imaging-guided biopsy currently represents one of the predominant methods for obtaining tissue specimens in patients with lung nodules; in many cases treatment protocols are based on histological information; thus, biopsy is frequently performed, when technically feasible, or in case other techniques (such as bronchoscopy with lavage) are inconclusive. Results Although a coaxial system is suitable in any case, two categories of needles can be used: fine-needle aspiration biopsy (FNAB) and core-needle biopsy (CNB), with the latter demonstrated to have a slightly higher overall sensitivity, specificity and accuracy. Conclusion Percutaneous lung biopsy is a safe procedure even though a few complications are possible: pneumothorax, pulmonary haemorrhage and haemoptysis are common complications, while air embolism and seeding are rare, but potentially fatal complications

Hemosuccus Pancreaticus in the Era of Capsule Endoscopy and Double Balloon Enteroscopy Complicated by Multifocal Mycobacterium chelonae/abscessus Infection

Hemosuccus pancreaticus is a rare etiology of obscure gastrointestinal bleeding characterized by bleeding into the pancreatic duct. The diagnosis may be delayed for months to years, due to the episodic nature of bleeding and failure to consider the diagnosis. Patients often undergo multiple endoscopies and radiologic evaluations prior to diagnosis. Incidental gastrointestinal findings may lead to unnecessary endoscopic and surgical interventions. This report describes a patient with hemosuccus pancreaticus diagnosed in the era of video capsule endoscopy and double balloon enteroscopy, whose management was complicated by multifocal Mycobacteria chelonae/abscessus infection