Optimization and use of near infrared imaging to guide lymph node collection in rhesus macaques (Macaca mulatta).

BACKGROUND: Identification of lymph nodes (LNs) draining a specific site or in obese macaques can be challenging. METHODS: Indocyanine Green (ICG) was administered intradermal (ID), intramuscular, in the oral mucosa, or subserosal in the colon followed by Near Infrared (NIR) imaging. RESULTS: After optimization to maximize LN identification, intradermal ICG was successful in identifying 50-100% of the axillary/inguinal LN at a site. Using NIR, collection of peripheral and mesenteric LNs in obese macaques was 100% successful after traditional methods failed. Additionally, guided collection of LNs draining the site of intraepithelial or intramuscular immunization demonstrated significantly increased numbers of T follicular helper (Tfh) cells in germinal centers of draining compared to nondraining LNs. CONCLUSION: These imaging techniques optimize our ability to evaluate immune changes within LNs over time, even in obese macaques. This approach allows for targeted serial biopsies that permit confidence that draining LNs are being harvested throughout the study.

Ex Vivo Fluorescence Confocal Microscopy (FCM) Ensures Representative Tissue in Prostate Cancer Biobanking: A Feasibility Study.

BACKGROUND: Biobanking of prostate carcinoma is particularly challenging due to the actual cancer within the organ often without clear margins. Frozen sections are to date the only way to examine the biobank material for its tumor content. We used ex vivo fluorescence confocal microscopy (FCM) to analyze biobank samples prior to cryoasservation. METHODS: 127 punch biopsies were acquired from prostatectomy-specimens from 40 patients. These biopsies were analyzed with a Vivascope 2500-G4 prior to their transfer to the biobank. In difficult cases, larger samples of the prostatectomy specimens were FCM scanned in order to locate tumor foci. After patient acquisition, all samples were taken from the biobank and analyzed. We compared the results of the FCM examinations with the results of conventional histology and measured the DNA content. RESULTS: With upstream FCM, the tumor content of biobank samples could be determined with high confidence. The detection rate of representative biobank samples was increased due to the rapid feedback. The biobank samples were suitable for further molecular analysis. CONCLUSION: FCM allows for the first time lossless microscopic analysis of biobank samples prior to their cryoasservation and guarantees representative tumor and normal tissue for further molecular analysis.

Implementing Targeted Sampling: Lessons Learned from Recruiting Female Sex Workers in Baltimore, MD.

Globally, HIV prevention interventions have proven efficacious among street-based female sex workers (FSWs); yet, there is a dearth of US-based HIV prevention research among this group. The lack of research among FSWs in the USA is partially driven by challenges in recruiting members of this population. The purpose of this research is to describe how targeted sampling was employed to recruit a cohort of street-based FSWs for a study that examined the role of police in shaping the HIV risk environments of street-based FSWs in Baltimore, MD. Our research demonstrates that targeted sampling can be an advantageous strategy for recruiting hidden populations that are mobile and geographically dispersed.

Active Participatory Regional Surveillance for Notifiable Swine Pathogens.

We evaluated an active participatory design for the regional surveillance of notifiable swine pathogens based on testing 10 samples collected by farm personnel in each participating farm. To evaluate the performance of the design, public domain software was used to simulate the introduction and spread of a pathogen among 17,521 farms in a geographic region of 1,615,246 km2. Using the simulated pathogen spread data, the probability of detecting ≥ 1 positive farms in the region was estimated as a function of the percent of participating farms (20%, 40%, 60%, 80%, 100%), farm-level detection probability (10%, 20%, 30%, 40%, 50%), and regional farm-level prevalence. At 0.1% prevalence (18 positive farms among 17,521 farms) and a farm-level detection probability of 30%, the participatory surveillance design achieved 67%, 90%, and 97% probability of detecting ≥ 1 positive farms in the region when producer participation was 20%, 40%, and 60%, respectively. The cost analysis assumed that 10 individual pig samples per farm would be pooled into 2 samples (5 pigs each) for testing. Depending on the specimen collected (serum or swab sample) and test format (nucleic acid or antibody detection), the cost per round of sampling ranged from EUR 0.017 to EUR 0.032 (USD 0.017 to USD 0.034) per pig in the region. Thus, the analysis suggested that an active regional participatory surveillance design could achieve detection at low prevalence and at a sustainable cost.

Targeted sampling reduces the uncertainty in force of infection estimates from serological surveillance.

Age bins are frequently used in serological studies of infectious diseases in wildlife to deal with uncertainty in the age of sampled animals. This study analyzed how age binning and targeted sampling in serological surveillance affect the width of the 95% confidence interval (CI) of the estimated force of infection (FOI) of infectious diseases. We indicate that the optimal target population with the narrowest 95% CI differs depending on the expected FOI using computer simulations and mathematical models. In addition, our findings show that we can substantially reduce the number of animals required to infer transmission risk by tailoring targeted, age-based sampling to specific epidemiological situations.

Support for targeted sampling of red fox (Vulpes vulpes) feces in Sweden: a method to improve the probability of finding Echinococcus multilocularis.

BACKGROUND: Localized concentrations of Echinococcus multilocularis eggs from feces of infected red fox (Vulpes vulpes) can create areas of higher transmission risk for rodent hosts and possibly also for humans; therefore, identification of these areas is important. However, in a low prevalence environment, such as Sweden, these areas could be easily overlooked. As part of a project investigating the role of different rodents in the epidemiology of E. multilocularis in Sweden, fox feces were collected seasonally from rodent trapping sites in two regions with known parasite status and in two regions with unknown parasite status, 2013-2015. The aim was to evaluate background contamination in rodent trapping sites from parasite eggs in these regions. To maximize the likelihood of finding fox feces positive for the parasite, fecal collection was focused in habitats with the assumed presence of suitable rodent intermediate hosts (i.e. targeted sampling). Parasite eggs were isolated from feces through sieving-flotation, and parasite species were then confirmed using PCR and sequencing. RESULTS: Most samples were collected in the late winter/early spring and in open fields where both Arvicola amphibius and Microtus agrestis were captured. Fox feces positive for E. multilocularis (41/714) were found within 1-3 field collection sites within each of the four regions. The overall proportion of positive samples was low (≤5.4%) in three regions, but was significantly higher in one region (22.5%, P < 0.001). There was not a significant difference between seasons or years. Compared to previous national screenings, our sampling strategy identified multiple E. multilocularis positive feces in all four regions, including the two regions with previously unknown parasite status. CONCLUSIONS: These results further suggest that the distribution of E. multilocularis is highly aggregated in the environment and provide support for further development of a targeted sampling strategy. Our results show that it was possible to identify new areas of high contamination in low endemic environments. After further elaboration, such a strategy may be particularly useful for countries designing surveillance to document freedom from disease.

Nonrandom Distribution of Cabbage Aphids (Hemiptera: Aphididae) in Dryland Canola (Brassicales: Brassicaceae).

Characterization of spatial distribution patterns of pests in large-scale agricultural fields is important because these patterns affect the sampling effort needed to accurately detect and estimate their population density. In this study, we conducted experimental releases of alate cabbage aphids (Brevicoryne brassicae L.) into centers of small plots of canola (Brassica napus L.), and their gradual spread over a 7-wk period was characterized. The small-plot experiment demonstrated gradient effects from plot centers and a nonrandom vertical distribution, with initial colonization occurring on the abaxial side of lower canopy leaves and, later, highest numbers of cabbage aphids occurring on racemes. We also conducted large-scale distribution analyses of cabbage aphid infestations in two commercial canola fields, using visual inspection and sweep net sampling. We used canola plant phenological and landscape features as explanatory variables of the spatial distribution of cabbage aphid counts. These large-scale experiments showed strong edge effects with negative associations between cabbage aphid counts and distance to crop edges, including tree lines and contour banks. Cabbage aphid distribution was more effectively displayed using logistic regression than ordinary regression, Spatial Analysis by Distance IndicEs, or both. Based on the study findings, a nonrandom or optimized inspection approach is proposed to focus monitoring efforts on canola plants within 20 m from field edges with particular attention to the abaxial side of lower-canopy leaves. Detection of advanced cabbage aphid infestations should target the racemes within 20 m from field edges.

Preliminary investigation of differential tapelifting for sampling forensically relevant layered deposits.

The analysis of DNA mixtures can be problematic, especially when in trace quantities such as when a biological sample is deposited onto a substrate which contains background DNA (for example, in the case of touch DNA deposited onto a garment containing the wearer's DNA). We conducted a preliminary investigation into the possibility of removing such multi-donor deposits layer by layer using a differential tape-lifting method. Two types of tape were tested using two different numbers of applications for sampling layered deposits of touch DNA/touch DNA and touch DNA/saliva, both on the same polyester-cotton plain woven material. The data showed that there was no significant increase in the ratio of secondary to primary deposit when sampled in this manner, compared to direct extraction from cuttings of the touched fabric. A similar result was also obtained even when the deposits were on opposing surfaces of the fabric and the sampling was carried out on the secondary deposit side. These findings indicate that biological material, whether touch DNA or saliva, does not predominantly remain on the side of the fabric on which it is deposited (at least for plain-woven polyester-cotton). They also highlight the importance of considering substrate properties when making assumptions as to the resulting location of biological materials from a deposition event, and the necessity to conduct further research on the interactions between substrates and deposits.

Un estudio comparativo de tres métodos de muestreo para poblaciones ocultas ode difícil acceso / A comparison of three methods for sampling hard - to - reach or hidden populations

Los proyectos de investigación que necesitan reclutar participantes pertenecientesa poblaciones “ocultas” o “difíciles de encontrar” requieren de métodos de muestreoque no solo faciliten la recolección de los datos y la confidencialidad, sino tambiénque incrementen la validez externa y permitan hacer inferencias estadísticasapropiadas. Este artículo presenta tres métodos que han demostrado ser útiles enlos trabajos de investigación con estas poblaciones estigmatizadas, clandestinaso de difícil acceso: 1) Muestreo basado en sitios y horarios específicos (VenueBased Time- Location Sampling). 2) Muestreo de áreas en las que se localiza lapoblación blanco o población objeto de estudio (Targeted Sampling). 3) Muestreodirigido por el participante (Respondent Driven Sampling). Luego de analizar lascaracterísticas, ventajas y limitaciones de cada método de muestreo, se presentauna comparación de todos ellos en términos de validez externa, posibilidad deobtener muestras probabilísticas y empleo de investigación etnográfica.

Research projects that need to recruit “hard-to-reach” or “hidden populations”require sampling methods that not only facilitate data collection and confidentialitybut also increase external validity and allow for statistically appropriate inferences.This paper presents three sampling methods useful for researchers who workwith stigmatized hard-to-reach or clandestine populations: 1) Venue Based Time/Location Sampling, 2) Targeted Sampling; and 3) Respondent Driven Sampling.The characteristics, advantages and limitations for each method are analyzed.They are also compared in terms of the possibility of obtaining probabilisticsamples, external validity, and use of ethnographic research.

Projetos de pesquisa que necessitam recrutar participantes pertencentesa povoações “oculta” ou “difíceis de encontrar” requerem de métodos deamostragem que não só facilitem a colheita dos dados e a confidencialidade mastambém que aumentem a validade externa e permitam fazer inferências estatísticasapropriadas. Este artigo teórico apresenta três métodos que demonstraram serúteis nos trabalhos de pesquisa com estas povoações estigmatizadas, clandestinasou de difícil acesso: 1) Amostragem baseado em lugares e horários específicos(Venue Based Time- Location Sampling); 2) Amostragem de áreas nas quais selocaliza a população branco ou população objeto de estudo (Targeted Sampling);e 3) Amostragem dirigido pelo participante (Respondent Driven Sampling).Depois de analisar as características, vantagens e limitações de cada método deamostragem, se apresenta uma comparação de todos eles em termos de validadeexterna, possibilidade de obter amostras probabilísticas e emprego de pesquisaetnográfica.