Making sense of ultrahigh-resolution movement data: A new algorithm for inferring sites of interest

Decomposing the life track of an animal into behavioral segments is a fundamental challenge for movement ecology. The proliferation of high-resolution data, often collected many times per second, offers much opportunity for understanding animal movement. However, the sheer size of modern data sets means there is an increasing need for rapid, novel computational techniques to make sense of these data. Most existing methods were designed with smaller data sets in mind and can thus be prohibitively slow. Here, we introduce a method for segmenting high-resolution movement trajectories into sites of interest and transitions between these sites. This builds on a previous algorithm of Benhamou and Riotte-Lambert (2012). Adapting it for use with high-resolution data. The data's resolution removed the need to interpolate between successive locations, allowing us to increase the algorithm's speed by approximately two orders of magnitude with essentially no drop in accuracy. Furthermore, we incorporate a color scheme for testing the level of confidence in the algorithm's inference (high = green, medium = amber, low = red). We demonstrate the speed and accuracy of our algorithm with application to both simulated and real data (Alpine cattle at 1 Hz resolution). On simulated data, our algorithm correctly identified the sites of interest for 99% of "high confidence" paths. For the cattle data, the algorithm identified the two known sites of interest: a watering hole and a milking station. It also identified several other sites which can be related to hypothesized environmental drivers (e.g., food). Our algorithm gives an efficient method for turning a long, high-resolution movement path into a schematic representation of broadscale decisions, allowing a direct link to existing point-to-point analysis techniques such as optimal foraging theory. It is encoded into an R package called SitesInterest, so should serve as a valuable tool for making sense of these increasingly large data streams.

Opportunities for NanoTheranosis in Lung Cancer and Pulmonary Metastasis

Malignancies of the lungs, both primary and metastatic, are the leading cause of death worldwide. Over 1.5 million new cases of primary lung cancer are diagnosed annually worldwide with a dismal five-year survival rate of approximately 15%, which remains unchanged despite major efforts and medical advances. As expected, survival for patients with lung metastases is even worse at about 5%. Early detection and staging are fundamental in improving survival rates and selecting the most effective treatment strategies. Recently, nanoparticles have been developed for imaging and treating various cancers, including pulmonary malignancies. In this work, three different examples of nanoparticle configurations for cancer theranosis are presented, namely conventional spherical polymeric nanoparticles with a diameter of ~ 150 nm; and discoidal mesoporous silicon nanoconstructs and discoidal polymeric nanoconstructs with a diameter of ~ 1,000 nm and a height of 400 and 500 nm, respectively. The spherical nanoparticles accumulate in tumors by means of the well-known enhanced permeation and retention effect, whereas sub-micrometer discoidal nanoconstructs are rationally designed to adhere firmly to the tortuous tumor vasculature. All three nanoparticles are characterized for their in vivo performance in terms of magnetic resonance, positron-emission tomography (PET), and optical imaging. Preliminary data on the in vivo and ex vivo PET/CT imaging of breast cancer metastasis in the lungs using discoidal nanoconstructs is presented. In conclusion, opportunities for nanoparticle-based theranosis in primary lung cancer and pulmonary metastasis are presented and discussed.

Prognostic quantification of non-small cell lung cancer metastases to the lung

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Background: Lung is the most frequent organ site of metastases from non-small cell lung cancer (NSCLC), yet the impact of these metastases on the natural history of the disease has not been well elucidated. Part of the difficulty of evaluating the prognosis of lung metastases in NSCLC patients is the effect of metastases to other organ sites. Here we have studied the survival of patients with lung as the solitary or dominant site of metastases and correlated it with number and maximal size of tumors. Methods: Data from the M.D. Anderson Cancer Center Tumor Registry during 1998 to 2002 was interrogated. Of 1280 patients registering as new patients, 87 were evaluable as having lung as the only site of metastases on initial staging evaluation. Excluding 13 patients who had bronchioloalveolar carcinoma (BAC) or BAC features on histology, the remaining 74 patients’ baseline CT scans were reviewed and scored for 1) the maximal linear measurement of the largest lung tumor and 2) the number of lung nodules that were growing and consistent with lung metastases. Results: In non-BAC patients with lung only metastases, an inverse correlation is seen between maximal linear measurement of a patient’s largest lung metastasis on baseline staging and their subsequent survival. A similar inverse correlation is seen between the number of lung metastases and survival. When patients with subsequent development of other metastatic sites are excluded from the analysis, these correlations are strengthened. Also, in BAC patients with lung only metastases, a trend toward longer survival with fewer metastases was seen, but only 13 patients were evaluable. Formal statistical analysis of these results is pending. Conclusions: The number and size of lung metastases from NSCLC appear to be independent predictors of survival. This might be explained by lead-time bias where fewer lesions represent an earlier stage of metastatic disease, however, increasing number and size of metastases may also be multiplying the source for further metastatic spread of disease. This interpretation of data may justify the local therapy of individual lung metastases in oligometastatic disease by surgery, stereotactic radiosurgery, or radiofrequency ablation.

No significant financial relationships to disclose.

Radiotherapy patterns of care study in lung carcinoma

PURPOSE

For the first time, a lung Patterns of Care Study was conducted to determine the national patterns of radiation (RT) practice in patients treated for nonmetastatic lung cancer in 1998 to 1999.

MATERIALS AND METHODS

A national survey of randomly selected RT institutions in the United States was conducted using two-stage cluster sampling, stratified by practice type. Patients with nonmetastatic lung cancer (Karnofsky performance score [KPS] > or = 60), who received RT as definitive or adjuvant therapy, were randomly selected. To determine national estimates, sample size was weighted by the relative number of institutions per strata and the number of patient records reviewed per the number of patients eligible. Accordingly, 42,335 patient records from 58 institutions were reviewed by trained research associates. The unweighted sample size (or number of patients) was 541.

RESULTS

The histologies were small-cell lung cancer (SCLC) in 14.5% of patients versus non-small-cell lung cancer (NSCLC) in 85.5% of patients. The median age was 67 years (range, 29 to 92 years); 61% of patients were male, and 38% were current smokers. Bone scans and brain imaging were not obtained in 34% and 52% of clinical stage (CS) III NSCLC patients, respectively. Regarding treatment strategies, for SCLC and CS III NSCLC, chemotherapy plus RT was used significantly more than RT alone (P <.05); in CS I NSCLC, RT alone was the primary treatment (P <.05). Overall, 58% of patients received systemic therapy. On multivariate analysis, factors correlating with increased use of chemotherapy included younger age, histology (SCLC > NSCLC), increasing CS, increasing KPS, and lack of comorbidities. Only 3% of all patients were treated on prospective clinical trials.

CONCLUSION

This study establishes the general patterns of care for lung carcinoma in RT facilities within the United States. As supported by clinical trials, patients with limited-stage SCLC and CS III NSCLC received chemotherapy plus RT more than they received RT alone. Further improvements in staging, smoking cessation, and increased accrual to clinical trials must be encouraged.

Coronary artery dosimetry in intact left breast irradiation

PURPOSE

The purpose of this article is to report dose-volume histograms of coronary vessels from irradiation of the intact left breast.

PATIENTS AND METHODS

Fifteen women with cancer of the left breast underwent computed tomographic treatment planning for radiation treatments of an intact left breast. Images through the heart were reconstructed at 1-mm increments to permit contouring of the coronary vessels. Five treatment plans were created for each patient; one plan from the simulated treatment fields and four additional plans that were generated from virtual treatment fields created by shifting the isocenter 5 mm and 10 mm both superficially and deep. The radiation dose was calculated using a three-dimensional treatment planning system that incorporated heterogeneity correction factors.

RESULTS

With no adjustment to the perpendicular lung distance, a mean volume of 12% of the left anterior descending coronary artery received 20 Gy, 6% received 30 Gy, and 3% received 40 Gy. The dose to the left anterior descending coronary artery varied significantly with changes in the perpendicular lung distance. From the mean perpendicular lung distance of 1.87 for the simulated fields, a 5-mm increase in the perpendicular lung distance resulted in an increase of 20%, 15%, and 12% in the percentage of the left anterior descending coronary artery treated to 20 Gy, 30 Gy, and 40 Gy, respectively. With a 10-mm increase, the respective volumes were increased to 49%, 41%, and 34%, respectively. A 5-mm reduction of lung distance in the original plan resulted in a decrease of 10%, 5%, and 3% in the percentage treated to 20 Gy, 30 Gy, and 40 Gy, respectively. The dose to the left main coronary artery, the right main coronary artery, and the left circumflex coronary artery was limited to scatter and was less than 7 Gy. Changes in the perpendicular lung distance did not significantly affect the dose administered to these vessels.

DISCUSSION

The left anterior descending coronary artery is anatomically located at the edge of the cardiac silhouette on traditional treatment films. Small changes in the perpendicular lung distance can significantly change the dose delivered to this vessel. A fundamental change in the shape of the dose-volume histogram occurs at a perpendicular lung distance of 2.3 cm, whereas the dose is very low when the perpendicular lung distance is less than 1.3 cm. These points may serve as clinically important values in the treatment planning for cancer of an intact breast.

Multi-Institutional Phase I/II Trial of Oral Bexarotene in Combination With Cisplatin and Vinorelbine in Previously Untreated Patients With Advanced Non–Small-Cell Lung Cancer

PURPOSE: Bexarotene (Targretin; Ligand Pharmaceuticals, Inc, San Diego, CA) is a retinoid-X-receptor (RXR)-selective retinoid with preclinical antitumor activity in squamous cell cancers. In this phase I/II trial, we combined bexarotene with cisplatin and vinorelbine in the treatment of patients with non–small-cell lung cancer (NSCLC).

PATIENTS AND METHODS: Forty-three patients who had stage IIIB NSCLC with pleural effusion or stage IV NSCLC and had received no prior therapy received bexarotene in combination with cisplatin (100 mg/m2) and vinorelbine (alternating doses of 30 mg/m2 and 15 mg/m2). In the phase I portion, the daily dose of bexarotene was escalated in cohorts of three patients from 150 mg/m2 to 600 mg/m2, beginning 1 week before the start of the cisplatin-vinorelbine regimen. Once the maximum-tolerated dose (MTD) of bexarotene was determined, the study entered the phase II portion. Response rate was the primary end point; median survival time and 1-year survival rate were secondary end points.

RESULTS: In the phase I portion, the daily MTD of bexarotene was determined to be 400 mg/m2. Eight of 43 patients exhibited major responses. Seven (25%) of the 28 patients in the phase II portion responded to treatment. The median survival time in the phase II portion was 14 months; nine (32%) of the 28 patients were still alive at a minimum follow-up of 2 years. One-year and projected 3-year survival rates were 61% and 30%, respectively. The most common grade 3 and 4 adverse events were hyperlipemia, leukopenia, nausea, vomiting, pneumonia, dyspnea, anemia, and asthenia. Grade 3 and 4 laboratory abnormalities with incidences greater than 5% were decreased hemoglobin levels and WBC, absolute neutrophil, and absolute lymphocyte counts and increased prothrombin time and creatinine and amylase levels. Of the two cases of pancreatitis, one required hospitalization and both were associated with increased triglyceride levels. There was one death secondary to renal insufficiency unrelated to bexarotene treatment.

CONCLUSION: In patients with advanced NSCLC, bexarotene with cisplatin and vinorelbine yielded acceptable phase II response rates (25%) and was associated with better-than-expected survival (14-month median survival time; 61% 1-year, 32% 2-year, and 30% projected 3-year survival rates). The regimen should be studied in larger clinical trials.

Cystic pheochromocytoma: radiologic diagnosis

Cystic pheochromocytomas are unusual variants of adrenal pheochromocytomas. Computed tomography and pathologic findings in the two cases reported here illustrate three cardinal principles in the diagnosis of cystic pheochromocytomas: (1) A suprarenal cystic tumor discovered on CT may be the result of hemorrhage and necrosis of an adrenal pheochromocytoma. (2) The cystic pheochromocytoma typically exhibits areas of low attenuation, with Hounsfield units in the range of 5 to 15 and rim enhancement on contrast administration. (3) Incidental adrenal lesions with these features discovered on CT scanning are an indication for catecholamine assays to screen for pheochromocytoma.

Voltammetric study of salbutamol and application to its determination in a tablet dosage form and dissolution profiles for the dosage form

The oxidative voltammetric behaviour of salbutamol at a glassy carbon electrode surface has been studied using cyclic voltammetry and differential pulse voltammetry. Oxidation of the drug was effected in a single irreversible, adsorption-controlled step in phosphate buffer. The process was found to be dependent on the ionic strength and the pH of the supporting electrolyte. The response was evaluated with respect to accumulation time, scan rate and other variables. Using differential pulse voltammetry following electrochemical pretreatment of the electrode surface, the drug yielded a well-defined voltammetric response in phosphate buffer, pH 5.0, at +0.75 V (vs SCE). This process could be used to determine salbutamol concentrations in the range 8 x 10(-7) M to 8 x 10(-5) M with a detection limit of 2 x 10(-7) M. The method was applied, without any interferences from the excipients, to the determination of the drug in a tablet dosage form and in drug dissolution studies. The absolute recovery for salbutamol was greater than 95% at the concentration levels studied, and reproducible voltammetric signals were obtained with a relative standard deviation of 2.4% for n = 7 at a concentration level of 8 x 10(-5) M.

Differential pulse voltammetric determination of sumatriptan succinate (1:1) in a tablet dosage form

A voltammetric study of the oxidation of sumatriptan succinate (1:1) has been carried out at the glassy carbon electrode. This compound exhibited a single wave in Britton-Robinson buffer solutions of pH 2-11, with a maximum current at pH 5.0. The mechanism of oxidation was shown to be due to oxidation of the N-H group in the indole ring. Based on this study, a simple, rapid and sensitive voltammetric method was developed for the determination of the drug in a tablet dosage form.