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There is a need to quantify relationships among vegetation structure and soil properties in coastal areas to better understand resilience, erosion, land use impacts, eutrophication, and mobility in this terrain. Remote sensing observations have been shown to effectively capture both vegetation and soil properties. However, identifying linked vegetation-soil properties and inferring soil properties from remote sensing when vegetation obscures the pixels remains challenging. Leveraging multiscale and multisensor remote sensing data and fusion techniques, we investigated the capability to identify linked vegetation-soil properties and infer the strength and stability of a barrier island along a swath where the soil surface is bare to partially to fully obscured by vegetation. To this end, we asked (1) Which remote sensing and field measured vegetation properties relate most strongly to soil properties, especially strength and moisture? (2) Do observations of soil conditions, geotechnical descriptors, vegetation species and health, and sensible hyperspectral signatures (HSI) allow accurate characterization of the combined soil-vegetation complex? We used multilevel and multi-sensor ground-, uncrewed aerial system (UAS)-, and satellite-based observations, namely HSI, lidar, ground optical, and geotechnical measurements, to test the variability and relationships among remote sensing-based measurements and geotechnical measurements, such as soil bearing strength. Firstly, we found high capability of HSI data to discriminate soil and soil moisture when any soil was exposed (beach, foredune, back dune, and marsh) and discrimination of vegetation at UAS and satellite scale. We found strong relationships among relative vegetation structure and soil properties, namely biomass estimates and soil strength, when using combined ground-based observations and UAS-based HSI observations and relative high accuracy upscaling to high-resolution satellite level maps of soil and vegetation properties. In addition, we found that adding slope and aspect data moderately enhanced the assessment of soil strength parameters in vegetated areas, although improvement of lidar data collection protocols in subsequent data collections promise further improvements in upcoming studies. In areas with tallest vegetation or soils that were highly saturated (inundation), results were mixed, likely due to poorer inference of soil background from remote sensing and soil strength from field measurements approaching zero, respectively. However, using a combination of shortwave infrared data, full spectra for analyses (spectral unmixing, dimensionality analyses, and supervised classification techniques), water-specific indices, and vegetation type information, wetland soil delineation was improved. Differences in soil and vegetation properties detected using field optical measurements were used to test upscaling techniques, i.e. training, for UAS-based HSI. With the help from ground-based data, a framework of mapping vegetation and soil specific properties was developed which enabled finer spatial analyses to be carried out with respect to the interdependence of vegetation and soil properties from remote sensing observations on a coastal barrier island.

Improved understanding of vegetation impacts on soil strength could improve erosion and landslide assessment, stabilization and resilience efforts, and off-road vehicle mobility efforts while minimizing damage to vegetation or soil surfaces. It has been shown that belowground biomass, along with soil moisture and type, influences soil strength. Standard handheld geotechnical instruments, such as cone penetrometers, vane and torvane, typically used for measurements of soil strength were developed for civil engineering projects. These devices have been applied to studies in natural areas to determine shear strength profiles, namely wetlands, stream banks, slopes, and coastal dunes. However, in cases where soils are soft or complex, can be saturated, or where vegetation exists, such as coastal areas or wetlands, traditional geotechnical instruments provide uncertain and highly variable results, can miss vegetation contributions to soil strength, and are difficult to compare to one another. A few efforts exist to address these issues. In the case of wetlands, Sasser et al (2018) developed a Wetland Soil Strength Tester (WSST), which measures the torque required to shear the combined soil-vegetation wetland matrix using a four-pin design inserted into the wetland soil 15 cm. In our ongoing work to use remote sensing to map soil and vegetation properties, even when soil is obscured by vegetation, we found that the geotechnical measurements insufficiently capture soil strength in the presence of vegetation. We adapted the WSST design and systematically tested against traditional geotechnical measurements broadly (variety of vegetated terrain, mostly grasses and shrubs, ranging from low to high heights), not necessarily just wetlands, to investigate the utility of the measurements in applications where soil strength is a primary parameter. Soil types included sand, loam, and clay, and each were tested in wet and dry conditions. Measurements of peak torque were recorded at intervals of 90 degrees up to four revolutions with and without surface vegetation present to account for more soil properties than shear failure. Results of the analyses showed that the method can account for a greater variation in initial shear strength than the cone penetrometer-based cone index in soft to medium hard soils, such as wet and dry sands with vegetation and moist to wet clays. Analyses of torque-based measurements beyond initial shear, greater than 90 degrees, revealed a non-uniform and non-linear change in force required as sheared vegetation-soil matrix is further manipulated. Hard soils, especially dry clays were beyond the maximum limits of torque measurements and did not add valuable information beyond traditional geotechnical measurements. Based on these results, a preliminary model of the relationship between the torque-based measurement and the cone index was developed, terrain maps were enhanced, and further applications are being analyzed. The torque weighted index soil strength test techniques have potential application in stability, erosion, and mobility studies as well as our ongoing research in using remote sensing for indirect inferences of soil properties in vegetated areas.

One of the primary objectives of the Oncology Pathology Working Group (OPWG) is for oncologists and pathologists to collaboratively generate consensus documents to standardize aspects of and provide guidelines for veterinary oncologic pathology. Consensus is established through review of relevant peer-reviewed literature relative to a subgroup's particular focus. In this article, the authors provide a critical review of the current literature for the diagnosis of, and histopathologic prognostication for, canine cutaneous and oral/lip melanocytic neoplasms, suggest guidelines for reporting, provide recommendations for clinical interpretation, and discuss future directions. This document represents the opinions of the working group and the authors and does not constitute a formal endorsement by the American College of Veterinary Pathologists, American College of Veterinary Internal Medicine or the Veterinary Cancer Society.

PURPOSE OF REVIEW: Review recent literature investigating the relationship between bone health and sleep/circadian disruptions (e.g., abnormal sleep duration, night shift work). RECENT FINDINGS: Short and long sleep are associated with low bone mineral density (BMD). Recent data from observational studies identified an increased risk of fracture in women with short sleep. Studies suggest that age, sex, weight change, and concurrent circadian misalignment may modify the effects of sleep restriction on bone metabolism. Interventional studies demonstrate alterations in bone metabolism and structure in response to circadian disruption that could underlie the increased fracture risk seen with night shift work. The effects of sleep and circadian disruption during adolescence may have lifelong skeletal consequences if they adversely impact bone modeling. SUMMARY: Data suggest that short sleep and night shift work negatively impact bone metabolism and health. Rigorous studies of prevalent sleep and circadian disruptions are needed to determine mechanisms and develop prevention strategies to optimize lifelong skeletal health.

Osteoporosis screening, diagnosis, and treatment have gained much attention in the health care community over the past 2 decades. During this time, creation of multispecialty awareness programs (eg, “Own the Bone,” American Orthopedic Association; “Capture the Fracture,” International Osteoporosis Foundation) and improvements in diagnostic protocols have been evident. Significant advances in technology have elucidated elements of genetic predisposition for decreased bone mineral density in the aging population. Additionally, several novel drug therapies have entered the market and provide more options for primary care and osteoporosis specialists to medically manage patients at risk for fragility fractures. Despite this, adherence to osteoporosis screening and treatment protocols has been surprisingly low by health care practitioners, including orthopedic surgeons. Continued awareness and education of this skeletal disorder is crucial to effectively care for our aging population. [ Orthopedics . 2023;46(1):e20–e26.]

Trees absorb carbon and are our most powerful ally against climate change, but we still don't know their full potential. That is set to change, finds Christine Swanson

A critical consideration when remotely sensing forest structure is how data resolution impacts signal interpretation. Grain size and spacing between signals affect the discrimination and convolutio...

Riparian vegetation performs important ecosystems services, improving water quality, mitigating erosion, and maintaining regional plant and animal biodiversity. Regular annual flooding maintains riparian forests through an intermediate disturbance regime. In response, seasonally flooded vegetation has developed adaptations for seed dispersal and gas transfer to survive and reproduce while undergoing periods of flooding. In the Amazon, a dam building boom threatens the integrity of riparian vegetation by moving riparian corridors into dry-adapted ecosystems and reducing downstream flooding of riparian areas. Additionally, the region is undergoing intense development pressure resulting in the conversion of native riparian vegetation into agriculture. In this study, we measure how the installation of six large dams on the Tocantins River, coupled with land cover change from native forest and savanna to cattle pasture, has changed the land–water interface of this region. Using land cover data provided by MapBiomas, we quantified land cover change from 1985 to 2018 and measured changes in the riparian areas of the still free-flowing areas of the Tocantins River, riparian areas surrounding reservoirs, and in-stream vegetation dynamics. We found that deforestation in the riparian areas of the Tocantins River downstream of the dams is occurring at a higher rate than deforestation in the watershed. Additionally, reservoir filling resulted in creating hundreds of square kilometers of new riparian areas, pushing the riparian zone away from forest-dominated ecosystems into savanna-dominated areas. The quantity of in-stream vegetation throughout the study was dynamic and initially increased after damming before declining for the last decade of the study. Changes to native land cover in riparian areas of the Tocantins River threaten the integrity of ecosystem services provided by riparian vegetation and are likely to lead to further degradation of these areas.

ObjectiveDystonia is a complex movement disorder. Research progress has been difficult, particularly in developing widely effective therapies. This is a review of the current state of knowledge, research gaps, and proposed research priorities.MethodsThe NIH convened leaders in the field for a 2-day workshop. The participants addressed the natural history of the disease, the underlying etiology, the pathophysiology, relevant research technologies, research resources, and therapeutic approaches and attempted to prioritize dystonia research recommendations.ResultsThe heterogeneity of dystonia poses challenges to research and therapy development. Much can be learned from specific genetic subtypes, and the disorder can be conceptualized along clinical, etiology, and pathophysiology axes. Advances in research technology and pooled resources can accelerate progress. Although etiologically based therapies would be optimal, a focus on circuit abnormalities can provide a convergent common target for symptomatic therapies across dystonia subtypes. The discussions have been integrated into a comprehensive review of all aspects of dystonia.ConclusionOverall research priorities include the generation and integration of high-quality phenotypic and genotypic data, reproducing key features in cellular and animal models, both of basic cellular mechanisms and phenotypes, leveraging new research technologies, and targeting circuit-level dysfunction with therapeutic interventions. Collaboration is necessary both for collection of large data sets and integration of different research methods.

Riparian forests are ecotones that link aquatic and terrestrial habitats, providing ecosystem services including sediment control and nutrient regulation. Riparian forest function is intimately linked to river hydrology and floodplain dynamics, which can be severely altered by dams. The Tocantins River in the eastern Amazon has six mega-dams along its course. To understand the large-scale and cumulative impacts of multiple dams on the Tocantins floodplain, we quantified landscape-scale changes in floodplain extent, hydroperiod, and flood timing on a 145-km stretch of the river downstream of five dams. We used water level data from 1985 to 2019 to compare daily floodplain inundation dynamics before and after damming. We also developed models to examine the impacts of climate and land use change on hydrology of the Tocantins River. After installation of the first dam in 1998, an average of 82.3 km2 (63%) of the floodplain no longer flooded, overall average hydroperiod decreased by 15 days (11%), and flooding started an average of five days earlier. After all five dams were installed, 72% of the average pre-dam flooded area no longer flooded, average hydroperiod had decreased by 35%, and average inundation onset occurred 12 days later. These changes in floodplain hydrology appeared to be driven primarily by dam operations as we found no significant changes in precipitation over the study period. Increasing loss of natural vegetation in the watershed may play a role in changed hydrology but cannot explain the abrupt loss of floodplain extent after the first dam was installed. This is one of few studies to quantify dam-induced floodplain alteration at a landscape scale and to investigate impacts of multiple dams on a landscape. Our results indicate that the Tocantins River floodplain is undergoing drastic hydrologic alteration. The impacts of multiple dams are cumulative and non-linear, especially for hydroperiod and flood timing.

Introduction The use of telemedicine services may be effective in the perioperative management of patients with varicose veins. Methods Over a seven-month period, patients with varicose veins were evaluated in the virtual clinic via two-way secure videoconferencing or the traditional clinic by the same physician provider. Data sources included institutional Vascular Quality Initiative registry and patient satisfaction surveys. Results Among a total of 121 patients with varicose veins who underwent endovenous catheter ablation of the saphenous vein, 20 patients (16.5%) chose the telemedicine clinic (Group A) and 101 patients (83.5%) chose the traditional clinic (Group B) for their perioperative management. Comparing Group A and Group B, the mean age was 59.2 ± 12.1 versus 59.6 ± 13.0, respectively ( p = 0.944); women were 75% versus 73.3%, respectively ( p = 0.872); African Americans comprised 5% versus 22.8%, while Caucasians comprised 95% versus 63%, respectively ( p = 0.049). Half of the telemedicine patients had multiple virtual visits for a total of 31 virtual encounters. Among telemedicine patients using SurveyMonkey®, 29 telemedicine encounters (93.5%) reported that their virtual visit is “Yes, definitely” or “Yes, somewhat” more convenient over traditional methods. All patients answered that they were able to communicate clearly with the provider, able to have their questions answered, and able to clearly hear and see the provider via telemedicine methods. Discussion Telemedicine services enable another means to deliver high-quality care for patients with venous disease in a safe and coordinated manner. Patients with varicose veins are highly satisfied with the use of telehealth services over the traditional healthcare delivery model.

Purpose The use of fiducial markers or direct tumor visualization allows for tumor tracking and ultimately smaller planning target volume (PTV) margins in the treatment of lung tumors, yet many patients are either not amenable to fiducial marker placement or their tumors are unable to be visualized on orthogonal-axis x-ray images. Spine tracking is an alternative method for tumor localization but is limited by the assumption that the location of the lung tumor relative to the spine is constant. The purpose of this study was to quantify the additional PTV margin needed when spine tracking is used to ensure the internal target volume (ITV) receives the prescription dose during treatment. Methods and materials Daily cone beam computed tomography images, registered based on tumor position, from 63 patients with lung cancer treated with stereotactic body radiation therapy were collected and analyzed. Rigid registrations were reperformed so that the position of the spine on the cone beam computed tomography image was aligned to its position on the planning computed tomography. Shifts from the treatment position to the new position were recorded, and per-patient mean shifts and standard deviations were calculated, as well as group systematic and random standard deviations. These data were used with van Herk's margin recipe to determine the additional margin required to adequately treat the patient population if spine tracking were used instead of direct daily tumor imaging. A retrospective dosimetric analysis was also performed on 6 patients with lung cancer previously treated by CyberKnife using spine tracking to determine the potential decrease in target coverage attributable to insufficient margin on the ITV. This analysis was performed by shifting the PTV volume relative to the CyberKnife treatment geometry to simulate a setup error caused by tracking the spine as opposed to the tumor. Results The additional margins calculated by van Herk's margin recipe to adequately cover the ITV with the 95% isodose surface for 90% of the entire patient population in the vertical, longitudinal, and lateral directions were 6.4, 6.0, and 4.5 mm, respectively. The retrospective analysis showed a decrease in PTV coverage from 95.6% to 93.1% and an increase in new conformity index by 2.7% when the average shift data were used to simulate setup error. When the maximum shift data were used to simulate the worst possible outcome, PTV coverage decreased to 73.4% and the new conformity index increased by 26.8%. Conclusions Standard margins of 5 mm on the ITV for patients with lung cancer being treated with stereotactic body radiation therapy are insufficient and may result in geographic misses of the tumor when spine tracking is used to locate the position of the tumor in the lung. Therefore, we recommend the addition of 5-mm margins in all directions for a total of 10 mm to take into account the change in position of the tumor relative to the spine from the time of simulation to treatment.

Biomarkers for Parkinson's disease (PD) diagnosis, prognostication and clinical trial cohort selection are an urgent need. While many promising markers have been discovered through the National Institute of Neurological Disorders and Stroke Parkinson's Disease Biomarker Program (PDBP) and other mechanisms, no single PD marker or set of markers are ready for clinical use. Here we discuss the current state of biomarker discovery for platforms relevant to PDBP. We discuss the role of the PDBP in PD biomarker identification and present guidelines to facilitate their development. These guidelines include: harmonizing procedures for biofluid acquisition and clinical assessments, replication of the most promising biomarkers, support and encouragement of publications that report negative findings, longitudinal follow-up of current cohorts including the PDBP, testing of wearable technologies to capture readouts between study visits and development of recently diagnosed (de novo) cohorts to foster identification of the earliest markers of disease onset.

The goal of this study is to evaluate patterns of failure and survival in relation to HPV/p16 status in patients with oropharyngeal (OP) cancers who were treated with chemoradiotherapy. A retrospective review of 271 consecutive head and neck cancer patients with known HPV/p16 status treated between 2009 and 2012 were reviewed. Ninety-four were identified OP cancers. Ninety-five percent of patients were treated with intensity-modulated radiation therapy (IMRT) with or without systemic therapy. Diagnostic imaging was coregistered with the planning CT scan in order to assess radiation dose statistics for the failure site. The median follow-up time was 30 months. The estimated 3-year overall survival for the cohort was 63 %. There was a trend for improved survival in HPV/p16+ patients compared to HPV/p16− patients (75 vs 58 %, p = 0.052). Heavy smoking was related to worse survival. There was a nonsignificant increase in locoregional failure (15.4 vs 2.8 %, p = 0.127) and distant metastasis (12.5 vs 1.5 %, p = 0.108) in HPV/p16− compared to HPV/p16+ tumors. No neck failures occurred in the HPV/p16+ patients, while six neck failures occurred in HPV/p16− patients. There was no difference between elective nodal doses between the two groups. A lower mean elective nodal dose was significant for predicting neck failure (44.54Gy vs 55.19Gy, p = 0.042). HPV/p16− patients have trends toward worse overall survival, locoregional recurrence, and distant metastasis. Lower elective nodal doses in HPV/p16− patients may increase the risk for elective neck failure.

En este documento se informa sobre la fase de inscripción de un estudio de la historia natural de la neoplasia de cuello uterino basado en la población de Guanacaste, una provincia rural de Costa Rica con tasas constantemente elevadas de cáncer cervicouterino invasor. Las principales metas del estudio son investigar el papel de la infección por virus del papiloma humano (VPH) y otros factores relacionados con la etiología de la neoplasia cervicouterina de alto grado, así como evaluar las nuevas tecnologías de detección de cáncer de cuello uterino. Se comenzó por seleccionar una muestra aleatoria de segmentos censales y enumerar todas las mujeres de 18 años o más que residían en ellos, con ayuda de varios agentes de extensión del Ministerio de Salud de Costa Rica. De las 10 738 mujeres que reunían las condiciones exigidas para participar, se entrevistó a 10 049 (93,6%) que dieron su consentimiento informado por escrito. Una vez concluida la entrevista sobre los factores de riesgo de cáncer de cuello uterino, se les realizó un examen pélvico a las que declararon haber tenido actividad sexual previa. Dicho examen incluyó una determinación del pH vaginal y recolección de células del cuello de útero para diagnóstico citológico con tres técnicas diferentes. Se recolectaron otras células cervicouterinas para determinar la presencia y cantidad de ADN de 16 tipos diferentes de VPH y se tomaron dos imágenes fotográficas del cuello uterino, que fueron interpretadas en un establecimiento externo por un colposcopista experto. Por último, se tomaron muestras de sangre para inmunovaloración y análisis de micronutrientes. Las mujeres con diagnóstico citológico anormal o cervigrama positivo, junto con una muestra de todo el grupo, se enviaron a otros servicios para colposcopia, y se tomaron biopsias en los casos en que se observaron lesiones. El tamizaje realizado para efectos de la inscripción servirá de base para un estudio de casos prevalentes y controles (testigos) y se realizará un activo seguimiento de los miembros de la cohorte sin enfermedad grave, a intervalos no mayores de un año, para estudiar la historia natural de la infección por VPH y los orígenes de las lesiones intraepiteliales escamosas de alto grado. Aquí se dan detalles de la operación realizada sobre el terreno, con referencia en particular a la realización de esta clase de estudio en un país en desarrollo. También se presentan datos descriptivos de la prevalencia de la enfermedad y la exposición a varios factores de riesgo.This paper reports on the enrollment phase of a population-based natural history study of cervical neoplasia in Guanacaste, a rural province of Costa Rica with consistently high rates of invasive cervical cancer. The main goals of the study are to investigate the role of human papillomavirus (HPV) infection and its co-factors in the etiology of high-grade cervical neoplasia, and to evaluate new cervical cancer screening technologies. To begin, a random sample of censal segments was selected and enumeration of all resident women 18 years of age and over was conducted with the aid of outreach workers of the Costa Rican Ministry of Health. Of the 10 738 women who were eligible to participate, 10 049 (93.6%) were interviewed after giving written informed consent. After the interview on cervical cancer risk factors was administered, a pelvic examination was performed on those women who reported previous sexual activity. The pelvic examination included a vaginal pH determination and collection of cervical cells for cytologic diagnosis using three different techniques. Additional cervical cells were collected for determination of the presence and amount of DNA from 16 different types of HPV, and two photographic images of the cervix were taken and interpreted offsite by an expert colposcopist. Finally, blood samples were collected for immunologic and micronutrient assays. Women with any abnormal cytologic diagnosis or a positive Cervigram, as well as a sample of the whole group, were referred for colposcopy, and biopsies were taken when lesions were observed. The enrollment screening will serve as the basis for a prevalent case-control study, and the members of the cohort free from serious disease will be followed actively, at intervals of no more than a year, to study the natural history of HPV infection and the origins of high-grade squamous intraepithelial lesions (HSIL). Details of the field operation are outlined, with particular reference to the realization of this kind of study in developing countries. Descriptive data on the prevalence of disease and exposure to various risk factors are also presented.

Introduction: Reducing mean population sodium intake by ~1200 mg is projected to reduce thousands of deaths from heart disease and stroke and save billions of health care dollars annually. Twenty-four hour urine collection is recommended for assessing changes in mean population sodium intake, but can be difficult to implement. Predicting 24-hour urine sodium excretion using spot urines is not recommended due to diurnal variations in excretion. Further, sodium excretion patterns differ between black and white persons. We assessed the validity of previously published prediction equations for 24-hour sodium excretion in black and other young adults by timing of spot urine collection. Design: Of 481 adult volunteers aged 18-39 years (50% Blacks) asked to participate in a 2011 study in the Metropolitan DC area, 407 collected each urine void in a separate container for 24 hours. Four timed voids from the 24-h urine collection were selected (morning, afternoon, evening, and overnight) to use with previously published predictive equations. Predictive equations were based on one of two approaches; 1) an indirect approach using spot urine sodium-to-creatinine concentrations and predicted 24-hour creatinine excretion ( Tanaka, Kawasaki, Mage ), and 2) a direct approach using spot urine sodium, potassium, and creatinine concentrations, and age, and body mass index with separate equations by sex ( Brown ). We assessed mean differences between predicted and measured 24-hour sodium excretion (bias) and individual differences across levels of sodium excretion using Bland-Altman plots. Results: Among participants, mean measured 24-hour sodium excretion was ~3300 mg (SD ~1400 mg). Of the equations evaluated, mean bias in predicted 24-hour sodium excretion was least from Brown equations when using morning (-165 mg, 95% confidence interval [CI], -295, -36 mg), afternoon (-90 mg, 95% CI, -208, 28 mg) or evening ( -120 mg, 95% CI -230, -11 mg) spot urines. When using overnight spot urines, mean bias from Brown equations was greatest and statistically significant (-247 mg, 95% CI, -348, -151 mg). When using overnight spot urines, mean bias from Tanaka (-23 mg) or Mage (-145 mg) equations was not significant, however, when stratified by sex, mean biases were significant and in opposite directions. Among Blacks, mean biases from Brown were not significant (-167 to 122 mg) except using overnight specimens among Black females (-267 mg, 95% CI, -525, -47 mg). Across equations and time periods, Bland-Altman plots indicated significant bias at the individual level. Conclusions: Of the evaluated equations, predicted 24-hour urine sodium excretion using the Brown equations with morning, afternoon, or evening specimens may provide the least biased estimates of group mean sodium intake among young US adults. None of the equations adequately predicted individual 24-hour sodium excretion measured on the same day.

En este documento se informa sobre la fase de inscripción de un estudio de la historia natural de la neoplasia de cuello uterino basado en la población de Guanacaste, una provincia rural de Costa Rica con tasas constantemente elevadas de cáncer cervicouterino invasor. Las principales metas del estudio son investigar el papel de la infección por virus del papiloma humano (VPH) y otros factores relacionados con la etiología de la neoplasia cervicouterina de alto grado, así como evaluar las nuevas tecnologías de detección de cáncer de cuello uterino. Se comenzó por seleccionar una muestra aleatoria de segmentos censales y enumerar todas las mujeres de 18 años o más que residían en ellos, con ayuda de varios agentes de extensión del Ministerio de Salud de Costa Rica. De las 10 738 mujeres que reunían las condiciones exigidas para participar, se entrevistó a 10 049 (93,6%) que dieron su consentimiento informado por escrito. Una vez concluida la entrevista sobre los factores de riesgo de cáncer de cuello uterino, se les realizó un examen pélvico a las que declararon haber tenido actividad sexual previa. Dicho examen incluyó una determinación del pH vaginal y recolección de células del cuello de útero para diagnóstico citológico con tres técnicas diferentes. Se recolectaron otras células cervicouterinas para determinar la presencia y cantidad de ADN de 16 tipos diferentes de VPH y se tomaron dos imágenes fotográficas del cuello uterino, que fueron interpretadas en un establecimiento externo por un colposcopista experto. Por último, se tomaron muestras de sangre para inmunovaloración y análisis de micronutrientes. Las mujeres con diagnóstico citológico anormal o cervigrama positivo, junto con una muestra de todo el grupo, se enviaron a otros servicios para colposcopia, y se tomaron biopsias en los casos en que se observaron lesiones. El tamizaje realizado para efectos de la inscripción servirá de base para un estudio de casos prevalentes y controles (testigos) y se realizará un activo seguimiento de los miembros de la cohorte sin enfermedad grave, a intervalos no mayores de un año, para estudiar la historia natural de la infección por VPH y los orígenes de las lesiones intraepiteliales escamosas de alto grado. Aquí se dan detalles de la operación realizada sobre el terreno, con referencia en particular a la realización de esta clase de estudio en un país en desarrollo. También se presentan datos descriptivos de la prevalencia de la enfermedad y la exposición a varios factores de riesgo.