Fallacies of preoperative lymphoscintigraphy in detecting sentinel node in breast cancer

BACKGROUND: Preoperative lymphoscintigraphy is one of the three methods of evaluating sentinel nodes in patients with breast cancer; however, it has been reported to have a high false negative rate. CASE PRESENTATIONS: We report here two cases where the preoperative lymphoscintigraphy was found to be fallacious. A 44-year-old female with T2N0 breast cancer underwent preoperative lymphoscintigraphy with Tc(99 )sulfur colloid which failed to show any uptake in axilla or internal mammary chain. Intraoperative scintigraphy with blue dye and hand held gamma probe identified sentinel lymph node in axilla. Another patient with T2N0 lesion underwent preoperative lymphoscintigraphy which showed a sentinel lymph node in axilla and another in supraclevicular fossa. Intraoperative scintigraphy failed to show supraclevicular node however axillary node was correctly identified. CONCLUSION: These two cases further strengthen the need to carry out triple test in identification of sentinel lymph node in patients with breast cancer. It also demonstrates the fallacies of preoperative lymphoscintigraphy

A foreign body in the urinary bladder leads to bladder stone and vesicorectal fistula: A case report

The case in this study was presented, the features in the diagnosis and treatment of rare complications such as bladder stone and vesicorectal fistula caused by the injection needle, which is a foreign body in the bladder. A 1-year-old male child came to our outpatient department with chief complaints of straining during micturition, dribbling of urine and history of high-grade fever, chills & rigor. A kidney, ureter, and bladder (KUB) X-ray revealed an approximately 1.5 cm bladder stone with radiopaque linear foreign body. On diagnostic cystoscopy anterior, posterior urethra was normal, fecal debris, stone and a needle was seen coming out through posterior wall of bladder. Open anterior cystolithotomy was done to remove 1.5-cm stone and a foreign body described as injection needle 24 gauge surrounded with fecal debris coming out through posterior wall was also removed. Fistulous tract was present and probed with 5 Fr feeding tube. A diversion colostomy was done. Patient discharged with colostomy and in follow up after 1 month micturating cystourethrogram (MCU) and distal loopogram of colon were normal; no fistulous communication present. Colostomy was closed after 3 months. There has been many cases reported in literature about insertion of different foreign bodies in bladder but foreign body ( injection needle) leading to bladder stone and vesicorectal fistula  is first of its kind as far as our knowledge is concerned

Maintaining real-time precise point positioning during outages of orbit and clock corrections

The precise point positioning (PPP) is a popular positioning technique that is dependent on the use of precise orbits and clock corrections. One serious problem for real-time PPP applications such as natural hazard early warning systems and hydrographic surveying is when a sudden communication break takes place resulting in a discontinuity in receiving these orbit and clock corrections for a period that may extend from a few minutes to hours. A method is presented to maintain real-time PPP with 3D accuracy less than a decimeter when such a break takes place. We focus on the open-access International GNSS Service (IGS) real-time service (RTS) products and propose predicting the precise orbit and clock corrections as time series. For a short corrections outage of a few minutes, we predict the IGS-RTS orbits using a high-order polynomial, and for longer outages up to 3 h, the most recent IGS ultra-rapid orbits are used. The IGS-RTS clock corrections are predicted using a second-order polynomial and sinusoidal terms. The model parameters are estimated sequentially using a sliding time window such that they are available when needed. The prediction model of the clock correction is built based on the analysis of their properties, including their temporal behavior and stability. Evaluation of the proposed method in static and kinematic testing shows that positioning precision of less than 10 cm can be maintained for up to 2 h after the break. When PPP re-initialization is needed during the break, the solution convergence time increases; however, positioning precision remains less than a decimeter after convergence

Linkages among forest, water, and wildlife: a case study from Kalapani community forest in Lamahi bottleneck area in Terai Arc Landscape.

Forest and water are important entities for sustaining life on earth. In a terrestrial ecosystem, linkages between the entities creates a mosaic benefiting the wildlife by creating the suitable habitat. In turn, communities get benefits stemming up from ecosystem services such as fodder, fuelwood, and water. We present a case study from a forest restoration project to assess the linkages between forest, water and wildlife across Lamahi bottleneck area in Terai Arc Landscape. We used combination of surveys such as forest area and canopy cover change (2001-2016) analysis followed by household questionnaire, water hole, camera trapping including process documentation. Forest area has increased by ~20 km2 in last 16 yrs. followed by number of water spouts along the identified tributaries. Water spouts are conserved in the form of conservation pond by the communities living downstream and utilized in the vegetable farming. Communities have benefited financially (~ US$ 1,252) contributing to their income level from the sale of fresh season vegetables in nearby market. Camera trap survey including the assessment of historical records showed presence of wildlife including elephant, hyena and other small carnivores in and around bottleneck forest. Both, motivation and enthusiastic support from local communities followed by the conducive government policies led to improve condition of natural resources over the period. This has also created a mosaic habitat for wildlife forming functional connectivity along the linear Terai Arc Landscape

A Targeted and Adjuvanted Nanocarrier Lowers the Effective Dose of Liposomal Amphotericin B and Enhances Adaptive Immunity in Murine Cutaneous Leishmaniasis

Background: Amphotericin B (AmB), the most effective drug against leishmaniasis, has serious toxicity. As Leishmania species are obligate intracellular parasites of antigen presenting cells (APC), an immunopotentiating APC-specific AmB nanocarrier would be ideally suited to reduce the drug dosage and regimen requirements in leishmaniasis treatment. Here, we report a nanocarrier that results in effective treatment shortening of cutaneous leishmaniasis in a mouse model, while also enhancing L. major specific T-cell immune responses in the infected host. Methods: We used a Pan-DR-binding epitope (PADRE)-derivatized-dendrimer (PDD), complexed with liposomal amphotericin B (LAmB) in an L. major mouse model and analyzed the therapeutic efficacy of low-dose PDD/ LAmB vs full dose LAmB. Results: PDD was shown to escort LAmB to APCs in vivo, enhanced the drug efficacy by 83% and drug APC targeting by 10-fold and significantly reduced parasite burden and toxicity. Fortuitously, the PDD immunopotentiating effect significantly enhanced parasite-specific T-cell responses in immunocompetent infected mice. Conclusions: PDD reduced the effective dose and toxicity of LAmB and resulted in elicitation of strong parasite specific T-cell responses. A reduced effective therapeutic dose was achieved by selective LAmB delivery to APC, bypassing bystander cells, reducing toxicity and inducing antiparasite immunity

Improving Precise Point Positioning Performance Using Multi-Frequency Multi-Constellation GNSS

The main drawback of Precise Point Positioning (PPP) is a long convergence time. This thesis integrates Multi-Frequency Multi-Constellation (MFMC) GNSS data to improve PPP convergence. The biases that occur during data integration were identified and modelled. Triple-frequency data was used to improve both float ambiguity and integer ambiguity resolution PPP models. Precise atmospheric products were investigated for constraining the ionosphere and troposphere errors. A method was proposed for maintaining decimetre accuracy during communication outages

Triple Frequency precise point positioning with multi-constellation GNSS

The availability of signals on three or more frequencies from multiple GNSS constellations provides opportunities for improving precise point positioning (PPP) convergence time and accuracy, compared to when using dual-frequency observations from a single constellation. Although the multi-frequency and multi-constellation (MFMC) data may be used with present day precise orbit and clock products, there are several biases that must be considered to get the best results. When using IGS products, the precise orbit and clock corrections are generated using dual-frequency ionosphere-free combinations of a ‘base’ pair of signals, and usage of other signals in the PPP model results in differential code biases (DCB). Other biases to consider include differential phase biases (DPB) for the satellites and receiver and satellite antenna offsets for individual frequencies. Integrating multi-constellation data introduces additional biases, such as inter-system hardware and time biases and inter-frequency bias. Although the integration of MFMC data introduces such biases, it improves the measurement model strength and hence can potentially improve PPP performance through reducing solution convergence time and increasing precision and accuracy. A brief overview of the MFMC biases and strategies that may be used to treat them is discussed. A proposed PPP model that uses triple frequency ionosphere-free low-noise linear combination for float ambiguity estimation is tested and analysed. MFMC data from four Australian sites is used to demonstrate the improvements in PPP solution convergence time, accuracy and precision, when comparing single- to multi-constellation GNSS data

A method for precise point positioning with integer ambiguity resolution using triple-frequency GNSS data

This paper proposes a method for precise point positioning with integer ambiguity resolution (PPP-AR) using triple-frequency global navigation satellite systems (GNSS) data. Firstly, an enhanced linear combination is developed for rapid fixing of the extra wide-lane (EWL) and wide lane (WL) ambiguities. This combination has improved performance compared to the Melbourne–Wübbena linear combination, and has 6.7% lower measurement error for the GPS L1/L2 signals, 12.7% lower error for L1/L5, and 0.7% lower error for L2/L5. Comparable improvements were also determined for the Beidou and Galileo constellations. After fixing the EWL/WL ambiguities, a full-rank, triple-frequency carrier-phase-only PPP model is proposed with ionosphere constraints. The probability of AR success rate (Ps) is analysed with the LAMBDA method, using a range of carrier phase and regional ionospheric model (RIM) precisions. Results show that a Ps of 99% is achieved within four epochs of data with carrier phase std  =  0.002 m and RIM std  =  0.1 total electron content unit (TECU); and within six epochs when RIM std  =  0.5 TECU. When the carrier phase std was increased to 0.02 m (depicting high multipath conditions), and with use of a low-precision RIM (std  =  0.5 TECU), the proposed method gave significantly improved performance over the method proposed by Li et al (2014 GPS Solut. 18 429–42). The direct estimation of the more challenging narrow-lane (NL) integer ambiguity is analysed by multi-epoch averaging of a proposed geometry-free and ionosphere-free triple-frequency linear combination. Tests with GPS data showed that 65.4% of the NL ambiguities were fixed within 10 min, 90.2% within 20 min, and 95.6% within 30 min

Ionosphere Augmentation for Accelerated Convergence in Precise Point Positioning with Triple-frequency and GPS

A Precise Point Positioning (PPP) method is presented that uses raw triple-frequency GPS measurements augmented with a regional ionospheric model (RIM) for faster solution convergence. The proposed method has two characteristics. Firstly, there is no noise amplification since raw uncombined carrier phase and code measurements are used. This reduces the solution convergence time, contrary to the ionosphere-free linear combination with a noise amplification factor of 3 that is used in traditional dual-frequency model. Secondly, the ionosphere delay remaining in the uncombined equations is modelled using externally provided precise ionosphere corrections, hence reducing the number of parameters to be estimated. Triple frequency simulated data was used to validate the model using a fully operational GPS constellation at four sites in Australia for one week duration. The performance of 2-hourly PPP solutions were compared for three cases including (1) the proposed triple frequency raw uncombined model with treatment of the ionosphere delay using an externally provided model (2) triple frequency raw uncombined model with estimation of ionosphere error (i.e. without RIM) and (3) traditional dual frequency PPP model. The three cases were compared in terms of solution convergence time taken to achieve and maintain 3- dimensional (3D), horizontal and vertical positional accuracies of 1 decimeter and 5cm. The tests for the first case considered the use of varying precisions of the externally provided ionosphere model with standard deviations (std) of 0.1, 0.25, 0.5 and 1.0 TECU. Results from the comparison show that the best improvement was achieved with the proposed raw model when using a high precision ionosphere model with std = 0.1 TECU, where the convergence time to achieve sub-decimeter accuracy was reduced by 37%, 84% and 33% in the 3D, horizontal and vertical components. The most significant improvement was in the horizontal component since the ionospheric error mostly affects the height. The second model also outperformed the standard dual frequency model, but had less improvement in convergence time by 13%, 3% and 21% in the three components

Bridging Real-Time Precise Point Positioning in Natural Hazard Warning Systems during Outages of MADOCA Corrections

Real-time Precise Point Positioning (RT-PPP) is the primary positioning method used in natural hazard warning systems (NHWS), e.g. for monitoring tsunami and earthquakes. The Japanese Multi-GNSS Advanced Demonstration tool for Orbit and Clock Analysis (MADOCA) is a promising service that enables RT-PPP. Currently it includes GPS, GLONASS and QZSS orbits and clock corrections in addition to code biases. However, one concern for continuous hazard monitoring by using RT PPP is the severe decline of positioning accuracy if a discontinuity in receiving these corrections occur, for instance due to a temporary user modem failure. In this paper, we present a method that can sustain RT PPP with 3D accuracy less than 20 cm when such a break takes place. For short outages less than 30 minutes we predict MADOCA orbits using a Holt-Winters’ autoregressive model, and for longer outages up to 2 hrs, the most recent International GNSS Service (IGS) ultra-rapid orbits can be used for GPS observations. Moreover, the clock corrections are predicted as a time series using a joint quadratic polynomial and sinusoidal model. The best regression period to estimate the required model parameters is discussed based on autocorrelation analysis of the corrections. The time lengths of the sinusoidal terms are estimated from analysis of the data in the frequency-domain. The prediction model parameters are estimated sequentially using a sliding time window with short intervals to reduce the computational load. Evaluation of the proposed method is performed at a site resembling a NHWS station and positioning accuracy were compared for the cases when using the original corrections and when using the predicted corrections for 1 hr, assuming that within this period the outage can be fixed. The experimental results proved validity of the presented approach where positioning accuracy of 20 cm was maintained during the prediction period