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1.  Recombinase Polymerase Amplification-Based Assay to Diagnose Giardia in Stool Samples 
Giardia duodenalis is one of the most commonly identified parasites in stool samples. Although relatively easy to treat, giardiasis can be difficult to detect as it presents similar to other diarrheal diseases. Here, we present a recombinase polymerase amplification-based Giardia (RPAG) assay to detect the presence of Giardia in stool samples. The RPAG assay was characterized on the bench top using stool samples spiked with Giardia cysts where it showed a limit-of-detection nearly as low as the gold standard polymerase chain reaction assay. The RPAG assay was then tested in the highlands of Peru on 104 stool samples collected from the surrounding communities where it showed 73% sensitivity and 95% specificity against a polymerase chain reaction and microscopy composite gold standard. Further improvements in clinical sensitivity will be needed for the RPAG assay to have clinical relevance.
PMCID: PMC4350554  PMID: 25510713
2.  Quantitative Analysis of High-Resolution Microendoscopic Images for Diagnosis of Esophageal Squamous Cell Carcinoma 
Background & Aims
High-resolution microendoscopy is an optical imaging technique with the potential to improve the accuracy of endoscopic screening for esophageal squamous neoplasia. Although these microscopic images can readily be interpreted by trained personnel, quantitative image analysis software could facilitate the use of this technology in low-resource settings. In this study we developed and evaluated quantitative image analysis criteria for the evaluation of neoplastic and non-neoplastic squamous esophageal mucosa.
We performed image analysis of 177 patients undergoing standard upper endoscopy for screening or surveillance of esophageal squamous neoplasia, using high-resolution microendoscopy, at 2 hospitals in China and 1 in the United States from May 2010 to October 2012. Biopsies were collected from imaged sites (n=375); a consensus diagnosis was provided by 2 expert gastrointestinal pathologists and used as the standard.
Quantitative information from the high-resolution images was used to develop an algorithm to identify high-grade squamous dysplasia or invasive squamous cell cancer, based on histopathology findings. Optimal performance was obtained using mean nuclear area as the basis for classification, resulting in sensitivities and specificities of 93% and 92% in the training set, 87% and 97% in the test set, and 84% and 95% in an independent validation set, respectively.
High-resolution microendoscopy with quantitative image analysis can aid in the identification of esophageal squamous neoplasia. Use of software-based image guides may overcome issues of training and expertise in low-resource settings, allowing for widespread use of these optical biopsy technologies.
PMCID: PMC4305504  PMID: 25066838
esophageal cancer; HRME; quantitative diagnosis; diagnostic
3.  A paper and plastic device for the combined isothermal amplification and lateral flow detection of Plasmodium DNA 
Malaria Journal  2015;14:472.
Isothermal amplification techniques are emerging as a promising method for malaria diagnosis since they are capable of detecting extremely low concentrations of parasite target while mitigating the need for infrastructure and training required by other nucleic acid based tests. Recombinase polymerase amplification (RPA) is promising for further development since it operates in a short time frame (<30 min) and produces a product that can be visually detected on a lateral flow dipstick. A self-sealing paper and plastic system that performs both the amplification and detection of a malaria DNA sequence is presented.
Primers were designed using the NCBI nBLAST tools and screened using gel electrophoresis. Paper and plastic devices were prototyped using commercial design software and parts were cut using a laser cutter and assembled by hand. Synthetic copies of the Plasmodium 18S gene were spiked into solution and used as targets for the RPA reaction. To test the performance of the device the same samples spiked with synthetic target were run in parallel both in the paper and plastic devices and using conventional bench top methods.
Novel RPA primers were developed that bind to sequences present in the four species of Plasmodium which infect humans. The paper and plastic devices were found to be capable of detecting as few as 5 copies/µL of synthetic Plasmodium DNA (50 copies total), comparable to the same reaction run on the bench top. The devices produce visual results in an hour, cost approximately $1, and are self-contained once the device is sealed.
The device was capable of carrying out the RPA reaction and detecting meaningful amounts of synthetic Plasmodium DNA in a self-sealing and self-contained device. This device may be a step towards making nucleic acid tests more accessible for malaria detection.
PMCID: PMC4661981  PMID: 26611141
Paper microfluidics; Recombinase polymerase amplification; Nucleic acid test
4.  Applications and Advancements in the use of High-Resolution Microendoscopy for Detection of Gastrointestinal Neoplasia 
The high-resolution microendoscope (HRME) is a novel imaging modality that allows real-time epithelial imaging at subcellular resolution. Used in concert with any standard endoscope, this portable, low cost, ‘optical biopsy’ technology has the ability to provide images of cellular morphology during a procedure. This technology has been the subject of a number of studies investigating its use in screening and surveillance of a range of gastrointestinal neoplasia, including esophageal adenocarcinoma(EAC), esophageal squamous cell cancer(ESCC), colorectal neoplasia(CRC) and anal neoplasia. These studies have shown that HRME is a modality that consistently provides high specificity, negative predictive value, and accuracy across different diseases. In addition, they have illustrated that HRME users can be relatively easily trained in a short period of time and that users have demonstrated solid inter-rater reliability. These features make HRME a potential complement to high definition white light imaging, narrow band imaging and other ‘red flag technologies’ in facilitating real-time clinical diagnosis, endoscopic therapy and margin determination. Further clinical validation is needed to determine whether this translates to reduced procedure times, pathology costs, and follow up procedures. Finally, the HRME has a relatively simple design compared to other similar technologies, making it portable, simple to maintain, and low cost. This may allow the HRME device to function in both advanced care settings as well as in places with less resources and specialized support systems. As a whole, the HRME device has shown good performance along with low-cost and portable construction, and its application in different conditions and settings has been promising.
PMCID: PMC4250374  PMID: 25108219
5.  All-plastic, miniature, digital fluorescence microscope for three part white blood cell differential measurements at the point of care 
Biomedical Optics Express  2015;6(11):4433-4446.
Three-part differential white blood cell counts are used for disease diagnosis and monitoring at the point-of-care. A low-cost, miniature achromatic microscope was fabricated for identification of lymphocytes, monocytes, and granulocytes in samples of whole blood stained with acridine orange. The microscope was manufactured using rapid prototyping techniques of diamond turning and 3D printing and is intended for use at the point-of-care in low-resource settings. The custom-designed microscope requires no manual adjustment between samples and was successfully able to classify three white blood cell types (lymphocytes, granulocytes, and monocytes) using samples of peripheral whole blood stained with acridine orange.
PMCID: PMC4646550  PMID: 26601006
(170.2520) Fluorescence microscopy; (170.3880) Medical and biological imaging; (170.1470) Blood or tissue constituent monitoring
6.  Design of a New Type of Compact Chemical Heater for Isothermal Nucleic Acid Amplification 
PLoS ONE  2015;10(10):e0139449.
Previous chemical heater designs for isothermal nucleic acid amplification have been based on solid-liquid phase transition, but using this approach, developers have identified design challenges en route to developing a low-cost, disposable device. Here, we demonstrate the feasibility of a new heater configuration suitable for isothermal amplification in which one reactant of an exothermic reaction is a liquid-gas phase-change material, thereby eliminating the need for a separate phase-change compartment. This design offers potentially enhanced performance and energy density compared to other chemical and electric heaters.
PMCID: PMC4591995  PMID: 26430883
7.  Design and Performance of a Low-Cost, Handheld Reader for Diagnosing Anemia in Blantyre, Malawi 
Anemia, a condition characterized by insufficient hemoglobin, affects 56.2% of pregnant women and 66.1% of children under five in low-resource countries. Though hemoglobin concentration measurement is the most common laboratory test in the world, the high cost of disposables (>$1.00 per test in Malawi) limits its availability in these settings. We have demonstrated a spectrophotometric method that reduces the per-test cost of anemia diagnosis to under $0.01 by using chromatography paper as the only disposable. Improvements in the hand-held reader, including using laser modules and a reference photodiode, enabled repeatable results within and across devices. We evaluated this method by analyzing capillary blood samples from 70 patients in the pediatric ward of Queen Elizabeth Central Hospital, Blantyre, Malawi. ~90% of these samples were within 2 g/dL of the standard value, with higher accuracy on more anemic samples. Current work aims to improve this accuracy by converting the hemoglobin in the sample to the more stable form methemoglobin.
PMCID: PMC4409007  PMID: 25918750
8.  Low-Cost Disposable Cartridge for Performing a White Blood Cell Count and Partial Differential at the Point-of-Care* 
Being able to perform a white blood cell (WBC) count and differential is a crucial laboratory test for basic diagnostic practices. In this paper, we demonstrate proof of concept results for a disposable cartridge that could be used to perform a WBC count and 3-part differential at the point-of-care. The cartridge is composed of a glass slide, a layer of transfer tape, and a glass cover slip and incorporates acridine orange for cell staining and sub-type differentiation; the stained blood is then imaged, and image analysis techniques return a WBC count and 3-part differential. The cartridge was tested on a laboratory microscope with 3 normal samples, and had promising results with 85.7% of images resulting in a WBC count with ±15% of the true value. Further, the 3-part differential concentrations determined using the disposable cartridge had strong correlations with the true concentrations (R2 values of 0.9986, 0.9421, and 0.6942 for granulocytes, lymphocytes, and monocytes, respectively). Preliminary designs for a low-cost, portable microscope have been created and are currently being prototyped.
PMCID: PMC4409009  PMID: 25918749
9.  Point-of-care and point-of-procedure optical imaging technologies for primary care and global health 
Science translational medicine  2014;6(253):253rv2.
Leveraging advances in consumer electronics and wireless telecommunications, low-cost, portable optical imaging devices have the potential to improve screening and detection of disease at the point of care in primary health care settings in both low- and high-resource countries. Similarly, real-time optical imaging technologies can improve diagnosis and treatment at the point of procedure by circumventing the need for biopsy and analysis by expert pathologists, who are scarce in developing countries. Although many optical imaging technologies have been translated from bench to bedside, industry support is needed to commercialize and broadly disseminate these from the patient level to the population level to transform the standard of care. This review provides an overview of promising optical imaging technologies, the infrastructure needed to integrate them into widespread clinical use, and the challenges that must be addressed to harness the potential of these technologies to improve health care systems around the world.
PMCID: PMC4370289  PMID: 25210062
10.  Feasibility of Transoral Robotic-Assisted High Resolution Microendoscopic Imaging of Oropharyngeal Squamous Cell Carcinoma 
Head & neck  2015;37(8):E99-E102.
Transoral robotic-assisted oncologic surgery of the head and neck offers promising functional results. Nonetheless, the efficacy of oncologic surgery remains critically dependent on obtaining negative margins. We aimed to integrate a miniaturized high resolution fiberoptic microendoscope (HRME), which provides real time histological assessment, with the da Vinci robotic system (Intuitive Surgical Inc., Sunnyvale, CA).
Three patients undergoing transoral robotic surgery were prospectively enrolled. Optical imaging of the oropharynx was performed intraoperatively with the robotic-assisted HRME.
All patients underwent the procedure successfully with no complications. The HRME was successfully integrated with the Da Vinci Robotic system. Several sites of the oropharynx and associated malignancy were imaged, which correlated with the standard histopathological analysis.
Transoral robotic-assisted high resolution microendoscopic imaging of the oropharynx is a safe and technically feasible approach, providing a real time histological assessment and may serve as a valuable aid in oncologic surgery.
PMCID: PMC4478240  PMID: 25327825
Transoral robotic surgery; optical imaging; HRME; oropharynx; microendoscopy; squamous cell carcinoma
11.  In vivo microscopy of hemozoin: towards a needle free diagnostic for malaria 
Biomedical Optics Express  2015;6(9):3462-3474.
Clinical diagnosis of malaria suffers from poor specificity leading to overtreatment with antimalarial medications. Alternatives, like blood smear microscopy or antigen-based tests, require a blood sample. We investigate in vivo microscopy as a needle-free malaria diagnostic. Two optical signatures, birefringence and absorbance, of the endogenous malaria by-product hemozoin were evaluated as in vivo optical biomarkers. Hemozoin birefringence was difficult to detect in highly scattering tissue; however, hemozoin absorbance was observed in increasingly complex biological environments and detectable over a clinically-relevant range of parasitemia in vivo in a P. yoelii-infected mouse model of malaria.
PMCID: PMC4574671  PMID: 26417515
(170.0180) Microscopy; (170.1470) Blood or tissue constituent monitoring; (260.1440) Birefringence
12.  Micro-anatomical quantitative optical imaging: toward automated assessment of breast tissues 
Pathologists currently diagnose breast lesions through histologic assessment, which requires fixation and tissue preparation. The diagnostic criteria used to classify breast lesions are qualitative and subjective, and inter-observer discordance has been shown to be a significant challenge in the diagnosis of selected breast lesions, particularly for borderline proliferative lesions. Thus, there is an opportunity to develop tools to rapidly visualize and quantitatively interpret breast tissue morphology for a variety of clinical applications.
Toward this end, we acquired images of freshly excised breast tissue specimens from a total of 34 patients using confocal fluorescence microscopy and proflavine as a topical stain. We developed computerized algorithms to segment and quantify nuclear and ductal parameters that characterize breast architectural features. A total of 33 parameters were evaluated and used as input to develop a decision tree model to classify benign and malignant breast tissue. Benign features were classified in tissue specimens acquired from 30 patients and malignant features were classified in specimens from 22 patients.
The decision tree model that achieved the highest accuracy for distinguishing between benign and malignant breast features used the following parameters: standard deviation of inter-nuclear distance and number of duct lumens. The model achieved 81 % sensitivity and 93 % specificity, corresponding to an area under the curve of 0.93 and an overall accuracy of 90 %. The model classified IDC and DCIS with 92 % and 96 % accuracy, respectively. The cross-validated model achieved 75 % sensitivity and 93 % specificity and an overall accuracy of 88 %.
These results suggest that proflavine staining and confocal fluorescence microscopy combined with image analysis strategies to segment morphological features could potentially be used to quantitatively diagnose freshly obtained breast tissue at the point of care without the need for tissue preparation.
Electronic supplementary material
The online version of this article (doi:10.1186/s13058-015-0617-9) contains supplementary material, which is available to authorized users.
PMCID: PMC4545917  PMID: 26290094
13.  In-vivo classification of colorectal neoplasia using high-resolution microendoscopy: improvement with experience 
Background and Aims
High-resolution microendoscopy (HRME) is a novel, low-cost “optical biopsy” technology that allows for subcellular imaging. The study aim was to evaluate the learning curve of HRME for the differentiation of neoplastic from non-neoplastic colorectal polyps.
In a prospective cohort fashion, a total of 162 polyps from 97 patients at a single tertiary care center were imaged by HRME and classified in real-time as neoplastic (adenomatous, cancer) or non-neoplastic (normal, hyperplastic, inflammatory). Histopathology was the gold standard for comparison. Diagnostic accuracy was examined at three intervals over time throughout the study; the initial interval included the first 40 polyps, the middle interval included the next 40 polyps examined, and the final interval included the last 82 polyps examined.
Sensitivity increased significantly from the initial interval (50%) to the middle interval (94%, p = 0.02) and the last interval (97%, p = 0.01). Similarly, specificity was 69% for the initial interval but increased to 92% (p = 0.07) in the middle interval and 96% (p = 0.02) in the last interval. Overall accuracy was 63% for the initial interval and then improved to 93% (p = 0.003) in the middle interval and 96% (p = 0.0007) in the last interval.
In conclusion, this in-vivo study demonstrates that an endoscopist without prior colon HRME experience can achieve greater than 90% accuracy for identifying neoplastic colorectal polyps after 40 polyps imaged. HRME is a promising modality to complement white-light endoscopy in differentiating neoplastic from non-neoplastic colorectal polyps.
PMCID: PMC4504008  PMID: 25753782
Colorectal polyps; adenoma classification; microendoscopy
14.  Development and validation of a simple algorithm for initiation of CPAP in neonates with respiratory distress in Malawi 
Low-cost bubble continuous positive airway pressure (bCPAP) systems have been shown to improve survival in neonates with respiratory distress, in developing countries including Malawi. District hospitals in Malawi implementing CPAP requested simple and reliable guidelines to enable healthcare workers with basic skills and minimal training to determine when treatment with CPAP is necessary. We developed and validated TRY (T: Tone is good, R: Respiratory Distress and Y=Yes) CPAP, a simple algorithm to identify neonates with respiratory distress who would benefit from CPAP.
To validate the TRY CPAP algorithm for neonates with respiratory distress in a low-resource setting.
We constructed an algorithm using a combination of vital signs, tone and birth weight to determine the need for CPAP in neonates with respiratory distress. Neonates admitted to the neonatal ward of Queen Elizabeth Central Hospital, in Blantyre, Malawi, were assessed in a prospective, cross-sectional study. Nurses and paediatricians-in-training assessed neonates to determine whether they required CPAP using the TRY CPAP algorithm. To establish the accuracy of the TRY CPAP algorithm in evaluating the need for CPAP, their assessment was compared with the decision of a neonatologist blinded to the TRY CPAP algorithm findings.
325 neonates were evaluated over a 2-month period; 13% were deemed to require CPAP by the neonatologist. The inter-rater reliability with the algorithm was 0.90 for nurses and 0.97 for paediatricians-in-training using the neonatologist's assessment as the reference standard.
The TRY CPAP algorithm has the potential to be a simple and reliable tool to assist nurses and clinicians in identifying neonates who require treatment with CPAP in low-resource settings.
PMCID: PMC4484369  PMID: 25877290
Neonatology; Respiratory
15.  Confocal foveated endomicroscope for the detection of esophageal carcinoma 
Biomedical Optics Express  2015;6(7):2311-2324.
By mimicking the variable resolution of the human eye, a newly designed foveated endomicroscopic objective shows the potential to improve current endoscopic based techniques of identifying abnormal tissue in the esophagus and colon. The prototype miniature foveated objective is imaged with a confocal microscope to provide large field of view images combined with a high resolution central region to rapidly observe morphological structures associated with cancer development in a mouse model.
PMCID: PMC4505691  PMID: 26203363
(170.2150) Endoscopic imaging; (350.3950) Micro-optics; (170.3880) Medical and biological imaging; (170.3890) Medical optics instrumentation; (170.1790) Confocal microscopy
16.  High-resolution microendoscopy for esophageal cancer screening in China: A cost-effectiveness analysis 
AIM: To study the cost-effectiveness of high-resolution microendoscopy (HRME) in an esophageal squamous cell carcinoma (ESCC) screening program in China.
METHODS: A decision analytic Markov model of ESCC was developed. Separate model analyses were conducted for cohorts consisting of an average-risk population or a high-risk population in China. Hypothetical 50-year-old individuals were followed until age 80 or death. We compared three different strategies for both cohorts: (1) no screening; (2) standard endoscopic screening with Lugol’s iodine staining; and (3) endoscopic screening with Lugol’s iodine staining and an HRME. Model parameters were estimated from the literature as well as from GLOBOCAN, the Cancer Incidence and Mortality Worldwide cancer database. Health states in the model included non-neoplasia, mild dysplasia, moderate dysplasia, high-grade dysplasia, intramucosal carcinoma, operable cancer, inoperable cancer, and death. Separate ESCC incidence transition rates were generated for the average-risk and high-risk populations. Costs in Chinese currency were converted to international dollars (I$) and were adjusted to 2012 dollars using the Consumer Price Index.
RESULTS: The main outcome measurements for this study were quality-adjusted life years (QALYs) and incremental cost-effectiveness ratio (ICER). For the average-risk population, the HRME screening strategy produced 0.043 more QALYs than the no screening strategy at an additional cost of I$646, resulting in an ICER of I$11808 per QALY gained. Standard endoscopic screening was weakly dominated. Among the high-risk population, when the HRME screening strategy was compared with the standard screening strategy, the ICER was I$8173 per QALY. For both the high-risk and average-risk screening populations, the HRME screening strategy appeared to be the most cost-effective strategy, producing ICERs below the willingness-to-pay threshold, I$23500 per QALY. One-way sensitivity analysis showed that, for the average-risk population, higher specificity of Lugol’s iodine (> 40%) and lower specificity of HRME (< 70%) could make Lugol’s iodine screening cost-effective. For the high-risk population, the results of the model were not substantially affected by varying the follow-up rate after Lugol’s iodine screening, Lugol’s iodine test characteristics (sensitivity and specificity), or HRME specificity.
CONCLUSION: The incorporation of HRME into an ESCC screening program could be cost-effective in China. Larger studies of HRME performance are needed to confirm these findings.
PMCID: PMC4427673  PMID: 25987774
Cost-effectiveness analysis; Diagnostic imaging; Endoscopy; Esophageal squamous cell cancer; Simulation disease model
17.  Optical systems for point-of-care diagnostic instrumentation: analysis of imaging performance and cost 
Annals of biomedical engineering  2013;42(1):10.1007/s10439-013-0918-z.
One of the key elements in point-of-care (POC) diagnostic test instrumentation is the optical system required for signal detection and / or imaging. Many tests which use fluorescence, absorbance, or colorimetric optical signals are under development for management of infectious diseases in resource limited settings, where the overall size and cost of the device is of critical importance. At present, high-performance lenses are expensive to fabricate and difficult to obtain commercially, presenting barriers for developers of in vitro POC tests or microscopic image-based diagnostics. We recently described a compact “hybrid” objective lens incorporating both glass and plastic optical elements, with a numerical aperture of 1.0 and field-of-view of 250 m. This design concept may potentially enable mass-production of high-performance, low-cost optical systems which can be easily incorporated in the readout path of existing and emerging POC diagnostic assays.
In this paper, we evaluate the biological imaging performance of these lens systems in three broad POC diagnostic application areas; (1) bright field microscopy of histopathology slides, (2) cytologic examination of blood smears, and (3) immunofluorescence imaging. We also break down the fabrication costs and draw comparisons with other miniature optical systems. The hybrid lenses provided images with quality comparable to conventional microscopy, enabling examination of neoplastic pathology and infectious parasites including malaria and cryptosporidium. We describe how these components can be produced at below $10 per unit in full-scale production quantities, making these systems well suited for use within POC diagnostic instrumentation.
PMCID: PMC3872497  PMID: 24097204
POC optics; Miniature optics; Cost assessment; Diagnostic imaging performance
18.  Vital-dye-enhanced multimodal imaging of neoplastic progression in a mouse model of oral carcinogenesis 
Journal of Biomedical Optics  2013;18(12):126017.
In this longitudinal study, a mouse model of 4-nitroquinoline 1-oxide chemically induced tongue carcinogenesis was used to assess the ability of optical imaging with exogenous and endogenous contrast to detect neoplastic lesions in a heterogeneous mucosal surface. Widefield autofluorescence and fluorescence images of intact 2-NBDG-stained and proflavine-stained tissues were acquired at multiple time points in the carcinogenesis process. Confocal fluorescence images of transverse fresh tissue slices from the same specimens were acquired to investigate how changes in tissue microarchitecture affect widefield fluorescence images of intact tissue. Widefield images were analyzed to develop and evaluate an algorithm to delineate areas of dysplasia and cancer. A classification algorithm for the presence of neoplasia based on the mean fluorescence intensity of 2-NBDG staining and the standard deviation of the fluorescence intensity of proflavine staining was found to separate moderate dysplasia, severe dysplasia, and cancer from non-neoplastic regions of interest with 91% sensitivity and specificity. Results suggest this combination of noninvasive optical imaging modalities can be used in vivo to discriminate non-neoplastic from neoplastic tissue in this model with the potential to translate this technology to the clinic.
PMCID: PMC3869894  PMID: 24362926
optical imaging; fluorescence; microscopy; carcinogenesis; mouse cancer model; contrast agents
19.  Cost-effectiveness analysis of a low-cost bubble CPAP device in providing ventilatory support for neonates in Malawi – a preliminary report 
BMC Pediatrics  2014;14:288.
A low-cost bubble continuous positive airway pressure (bCPAP) device has been shown to be an excellent clinical alternative to nasal oxygen for the care of neonates with respiratory difficulty. However, the delivery of bCPAP requires more resources than the current routine care using nasal oxygen. We performed an economic evaluation to determine the cost-effectiveness of a low-cost bCPAP device in providing ventilatory support for neonates in Malawi.
We used patient-level clinical data from a previously published non-randomized controlled study. Economic data were based on the purchase price of supplies and equipment, adjusted for shelf life, as well as hospital cost data from the World Health Organization. Costs and benefits were discounted at 3%. The outcomes were measured in terms of cost, discounted life expectancy, cost/life year gained and net benefits of using bCPAP or nasal oxygen. The incremental cost-effectiveness ratio and incremental net benefits determined the value of one intervention compared to the other. Subgroup analysis on several parameters (birth weight categories, diagnosis of respiratory distress syndrome, and comorbidity of sepsis) was conducted to evaluate the effect of these parameters on the cost-effectiveness.
Nasal oxygen therapy was less costly (US$29.29) than the low-cost bCPAP device ($57.78). Incremental effectiveness associated with bCPAP was 6.78 life years (LYs). In the base case analysis, the incremental cost-effectiveness ratio for bCPAP relative to nasal oxygen therapy was determined to be $4.20 (95% confidence interval, US$2.29–US$16.67) per LY gained. The results were highly sensitive for all tested subgroups, particularly for neonates with birth weight 1– < 1.5 kg, respiratory distress syndrome, or comorbidity of sepsis; these subgroups had a higher probability that bCPAP would be cost effective.
The bCPAP is a highly cost-effective strategy in providing ventilatory support for neonates in Malawi.
PMCID: PMC4247223  PMID: 25421903
Cost-effectiveness analysis; Neonate; Malawi; Prematurity; Respiratory distress syndrome; Sepsis; Ventilatory support; Bubble continuous positive airway pressure
20.  Confocal fluorescence microscopy for rapid evaluation of invasive tumor cellularity of inflammatory breast carcinoma core needle biopsies 
Tissue sampling is a problematic issue for inflammatory breast carcinoma, and immediate evaluation following core needle biopsy is needed to evaluate specimen adequacy. We sought to determine if confocal fluorescence microscopy provides sufficient resolution to evaluate specimen adequacy by comparing invasive tumor cellularity estimated from standard histologic images to invasive tumor cellularity estimated from confocal images of breast core needle biopsy specimens. Grayscale confocal fluorescence images of breast core needle biopsy specimens were acquired following proflavine application. A breast-dedicated pathologist evaluated invasive tumor cellularity in histologic images with hematoxylin and eosin staining and in grayscale and false-colored confocal images of cores. Agreement between cellularity estimates was quantified using a kappa coefficient. 23 cores from 23 patients with suspected inflammatory breast carcinoma were imaged. Confocal images were acquired in an average of less than 2 min per core. Invasive tumor cellularity estimated from histologic and grayscale confocal images showed moderate agreement by kappa coefficient: κ = 0.48 ± 0.09 (p < 0.001). Grayscale confocal images require less than 2 min for acquisition and allow for evaluation of invasive tumor cellularity in breast core needle biopsy specimens with moderate agreement to histologic images. We show that confocal fluorescence microscopy can be performed immediately following specimen acquisition and could indicate the need for additional biopsies at the initial visit.
PMCID: PMC4298669  PMID: 25417171
Inflammatory breast cancer; Core needle biopsy; Confocal fluorescence microscopy; Tissue sampling
21.  Equipment-Free Incubation of Recombinase Polymerase Amplification Reactions Using Body Heat 
PLoS ONE  2014;9(11):e112146.
The development of isothermal amplification platforms for nucleic acid detection has the potential to increase access to molecular diagnostics in low resource settings; however, simple, low-cost methods for heating samples are required to perform reactions. In this study, we demonstrated that human body heat may be harnessed to incubate recombinase polymerase amplification (RPA) reactions for isothermal amplification of HIV-1 DNA. After measuring the temperature of mock reactions at 4 body locations, the axilla was chosen as the ideal site for comfortable, convenient incubation. Using commonly available materials, 3 methods for securing RPA reactions to the body were characterized. Finally, RPA reactions were incubated using body heat while control RPA reactions were incubated in a heat block. At room temperature, all reactions with 10 copies of HIV-1 DNA and 90% of reactions with 100 copies of HIV-1 DNA tested positive when incubated with body heat. In a cold room with an ambient temperature of 10 degrees Celsius, all reactions containing 10 copies or 100 copies of HIV-1 DNA tested positive when incubated with body heat. These results suggest that human body heat may provide an extremely low-cost solution for incubating RPA reactions in low resource settings.
PMCID: PMC4221156  PMID: 25372030
22.  Endoscopic ultrasound-assisted direct peritoneal visualization with a small-caliber scope: A proof of concept study in a swine model 
Endoscopic Ultrasound  2014;3(4):226-231.
Laparoscopic and natural orifice transluminal endoscopic surgery techniques can diagnose peritoneal findings that suggest tumor cell dissemination. However, they have not been incorporated into routine practice, mainly owing to their complexity. To develop a minimally invasive endoscopic technique for the diagnosis of peritoneal findings, we conducted feasibility study using an acute swine model.
Materials and Methods:
This study involved six domestic pigs. Trans-gastric access to the peritoneal cavity was performed utilizing an endoscopic ultrasound fine needle aspiration (EUS-FNA) technique. After dilation of the needle hole with a biliary dilatation catheter and balloon, a small-caliber scope was inserted into the peritoneal cavity. Peritoneal images were obtained with the scope and a high-resolution microendoscope (HRME). Main outcome measurements were technical feasibility and time needed to access the peritoneal cavity.
Direct visualization of the peritoneum was successful in all six pigs and gained access to the gross appearance of the peritoneal cavity. HRME imaging with topical contrast agent also obtained reasonable quality images representing nuclei of the peritoneal mesothelium. Average operation time from the initiation of EUS-FNA to acquiring peritoneal images was 26.5 min (range 15-40 min). Autopsy found no damage to the adjacent organs, and stomach wall defects were tightly closed with hemostasis clips.
EUS-assisted direct peritoneal visualization with small-caliber scope is technically feasible. HRME may assist in the diagnosis of findings on the peritoneum.
PMCID: PMC4247530  PMID: 25485270
Cancer staging; endoscopic ultrasound-guided fine needle aspiration; natural orifice transluminal endoscopic surgery; peritoneoscopy; tumor implant
23.  Optical Molecular Imaging in the Gastrointestinal Tract 
Recent developments in optical molecular imaging allow for real-time identification of morphological and biochemical changes in tissue associated with gastrointestinal neoplasia. This review summarizes widefield and high resolution imaging modalities currently in pre-clinical and clinical evaluation for the detection of colorectal cancer and esophageal cancer. Widefield techniques discussed include high definition white light endoscopy, narrow band imaging, autofluoresence imaging, and chromoendoscopy; high resolution techniques discussed include probe-based confocal laser endomicroscopy, high-resolution microendoscopy, and optical coherence tomography. Finally, new approaches to enhance image contrast using vital dyes and molecular-specific targeted contrast agents are evaluated.
PMCID: PMC3746803  PMID: 23735112
optical molecular imaging; white light endoscopy; narrow band imaging; autofluorescence imaging; chromoendoscopy; confocal laser endomicroscopy; high resolution microendoscopy; optical coherence tomography
24.  In vivo diagnostic accuracy of high resolution microendoscopy in differentiating neoplastic from non-neoplastic colorectal polyps: a prospective study 
High-resolution microendoscopy (HRME) is a low-cost, “optical biopsy” technology that allows for subcellular imaging. The purpose of this study was to determine the in vivo diagnostic accuracy of the HRME for the differentiation of neoplastic from non-neoplastic colorectal polyps and compare it to that of high-definition white-light endoscopy (WLE) with histopathology as the gold standard. Three endoscopists prospectively detected a total of 171 polyps from 94 patients that were then imaged by HRME and classified in real-time as neoplastic (adenomatous, cancer) or non-neoplastic (normal, hyperplastic, inflammatory). HRME had a significantly higher accuracy (94%), specificity (95%), and positive predictive value (87%) for the determination of neoplastic colorectal polyps compared to WLE (65%, 39%, and 55%, respectively). When looking at small colorectal polyps (less than 10 mm), HRME continued to significantly outperform WLE in terms of accuracy (95% vs. 64%), specificity (98% vs. 40%) and positive predictive value (92% vs. 55%). These trends continued when evaluating diminutive polyps (less than 5 mm) as HRME's accuracy (95%), specificity (98%), and positive predictive value (93%) were all significantly greater than their WLE counterparts (62%, 41%, and 53%, respectively). In conclusion, this in vivo study demonstrates that HRME can be a very effective modality in the differentiation of neoplastic and non-neoplastic colorectal polyps. A combination of standard white-light colonoscopy for polyp detection and HRME for polyp classification has the potential to truly allow the endoscopist to selectively determine which lesions can be left in situ, which lesions can simply be discarded, and which lesions need formal histopathologic analysis.
PMCID: PMC3947255  PMID: 24296752
Colorectal polyps; adenoma classification; microendoscopy; neoplasia; diagnostic accuracy
25.  Optical Imaging with a High Resolution Microendoscope to Identify Cholesteatoma of the Middle Ear 
The Laryngoscope  2013;123(4):1016-1020.
High resolution optical imaging is an imaging modality which allows visualization of structural changes in epithelial tissue in real time. Our prior studies using contrast-enhanced microendoscopy to image squamous cell carcinoma in the head and neck demonstrated that the contrast agent, proflavine, has high affinity for keratinized tissue. Thus, high-resolution microendoscopy with proflavine provides a potential mechanism to identify ectopic keratin production, such as that associated with cholesteatoma formation and distinguish between uninvolved mucosa and residual keratin at the time of surgery.
Study Design
Ex vivo imaging of histopathologically-confirmed samples of cholesteatoma and uninvolved middle-ear epithelium.
Seven separate specimens collected from patients who underwent surgical treatment for cholesteatoma were imaged ex vivo with the fiberoptic endoscope after surface staining with proflavine. Following imaging, the specimens were submitted for hematoxylin &eosin staining to allow histopathological correlation.
Cholesteatoma and surrounding middle ear epithelium have distinct imaging characteristics. Keratin-bearing areas of cholesteatoma lack nuclei and appear as confluent hyperfluorescence, while nuclei are easily visualized in specimens containing normal middle ear epithelium. Hyperfluorescence and loss of cellular detail is the imaging hallmark of keratin allowing for discrimination of cholesteatoma from normal middle ear epithelium.
This study demonstrates the feasibility of high-resolution optical imaging to discriminate cholesteatoma from uninvolved middle ear mucosa, based on the unique staining properties of keratin. Use of real-time imaging may facilitate more complete extirpation of cholesteatoma by identifying areas of residual disease.
PMCID: PMC3609873  PMID: 23299781
cholesteatoma; keratin; optical imaging; otology; high-resolution microendoscopy

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