Epidemiología y características anatomoclínicas del melanoma maligno en un instituto oncológico / Epidemiology and clinical features of malignant melanoma. Analysis of 274 cases

BACKGROUND: Malignant melanoma (MM) is the most fatal cutaneous neoplasm. Its incidence is increasing progressively, which cannot be explained only by early diagnosis. Chilean population, due to the geography of the country, has a very varied solar exposure. AIM: To know the incidence of MM in a Chilean population, according to the level of sun exposure and to describe its clinical and histopathological characteristics. MATERIAL AND METHODS: Two hundred seventy-four surgeries for malignant melanoma with histological confirmation, carried out between 2016 and 2018 in an oncological institute were included. RESULTS: The annualized incidence of MM was 13.83 cases per 100,000 people over 15 years of age in the 2016-2018 period. The geographical distribution of the incidence did not have a clear relationship with sun exposure. The most frequent locations of the primary lesions were trunk, head/neck and lower limb. Sixty-one per cent of cases were invasive MM; lesion thickness and presence of ulceration were associated with a higher risk of sentinel node involvement. CONCLUSIONS: No association between the level of sun exposure and the incidence of MM was observed in this study.

Protective effects of antioxidants on striatal dopamine release induced by organophosphorus pesticides.

Although the toxic effects of organophosphorus (OP) pesticides have been classically attributed to inhibition of the acetylcholinesterase, other neurotoxic mechanisms, as oxidative stress can also occur. Here we evaluated if antioxidants prevent the excessive dopamine release induced by OP pesticides in conscious and freely moving rats, using cerebral microdialysis technique. Intrastriatal infusion of paraoxon (5 mM), glufosinate (10 mM) or glyphosate (5 mM) significantly increased the dopamine release (1006 ± 106%, 991 ± 142%, and 1164 ± 128%, relative to baseline, respectively). To evaluate if these increased dopamine release could be related to oxidative stress, we pretreated animals with antioxidants glutathione (GSH, 400 or 800 µM), dithiothreitol (DTT, 5 or 10 µM), trolox (1 or 3 mM), and α-lipoic acid (ALA, 400 or 800 µM) before administration of OP pesticides. Intrastriatal administration of the antioxidants GSH, DTT, trolox, and ALA was highly effective in preventing the glyphosate and glufosinate-induced dopamine overflow. However, only GSH (800 µM) significantly decreased the effect of paraoxon on dopamine levels. The high toxicity of this pesticide and the low concentrations used could explain this lack of effect in our experimental conditions. The fact that ROS scavengers prevent the excessive dopamine release induced by OP pesticides, further supports the view that dopamine overflow can cause neuronal damage mediated, at least in part, by oxidative stress.

[Epidemiology and clinical features of malignant melanoma. Analysis of 274 cases]. / Epidemiología y características anatomoclínicas del melanoma maligno en un instituto oncológico.

BACKGROUND: Malignant melanoma (MM) is the most fatal cutaneous neoplasm. Its incidence is increasing progressively, which cannot be explained only by early diagnosis. Chilean population, due to the geography of the country, has a very varied solar exposure. AIM: To know the incidence of MM in a Chilean population, according to the level of sun exposure and to describe its clinical and histopathological characteristics. MATERIAL AND METHODS: Two hundred seventy-four surgeries for malignant melanoma with histological confirmation, carried out between 2016 and 2018 in an oncological institute were included. RESULTS: The annualized incidence of MM was 13.83 cases per 100,000 people over 15 years of age in the 2016-2018 period. The geographical distribution of the incidence did not have a clear relationship with sun exposure. The most frequent locations of the primary lesions were trunk, head/neck and lower limb. Sixty-one per cent of cases were invasive MM; lesion thickness and presence of ulceration were associated with a higher risk of sentinel node involvement. CONCLUSIONS: No association between the level of sun exposure and the incidence of MM was observed in this study.

COVID-19 fatality in Mexico's indigenous populations.

OBJECTIVE: The aim of the study was to explore the factors that could explain the differences in fatality rates among indigenous groups with COVID-19 diagnosis compared with the rest of the population in Mexico. STUDY DESIGN: We analyzed the public data of COVID-19 surveillance, of the Mexican Ministry of Health, to estimate COVID-19 fatality rates by ethnicity. METHODS: We explored associated factors using Cox proportional hazards models stratified by outpatient and hospital management at diagnosis; analysis was conducted in three scenarios: national level, states with 89% of the indigenous population, and South Pacific region. RESULTS: A total of 412,017 COVID-19 cases were included, with 1.1% of the indigenous population. The crude fatality rate per 1000 person-weeks was 64.8% higher among indigenous than among non-indigenous people (29.97 vs. 18.18, respectively), and it increased more than twice within outpatients (5.99 vs. 2.64, respectively). Cox analysis revealed that indigenous people who received outpatient management had higher fatality rate than non-indigenous outpatients, at the national level (hazard ratio [HR] = 1.63; 95% confidence interval [CI] = 1.34-1.98), within the subgroup of 13 states (HR = 1.66; 95% CI = 1.33-2.07), and in the South Pacific region (HR = 2.35; 95% CI = 1.49-3.69). Factors associated with higher fatality rates among non-indigenous and indigenous outpatients were age, sex, and comorbidities. CONCLUSIONS: COVID-19 fatality is higher among indigenous populations, particularly within cases managed as outpatients.

Development and large volume production of extremely high current density YBa2Cu3O7 superconducting wires for fusion.

The fusion power density produced in a tokamak is proportional to its magnetic field strength to the fourth power. Second-generation high temperature superconductor (2G HTS) wires demonstrate remarkable engineering current density (averaged over the full wire), JE, at very high magnetic fields, driving progress in fusion and other applications. The key challenge for HTS wires has been to offer an acceptable combination of high and consistent superconducting performance in high magnetic fields, high volume supply, and low price. Here we report a very high and reproducible JE in practical HTS wires based on a simple YBa2Cu3O7 (YBCO) superconductor formulation with Y2O3 nanoparticles, which have been delivered in just nine months to a commercial fusion customer in the largest-volume order the HTS industry has seen to date. We demonstrate a novel YBCO superconductor formulation without the c-axis correlated nano-columnar defects that are widely believed to be prerequisite for high in-field performance. The simplicity of this new formulation allows robust and scalable manufacturing, providing, for the first time, large volumes of consistently high performance wire, and the economies of scale necessary to lower HTS wire prices to a level acceptable for fusion and ultimately for the widespread commercial adoption of HTS.

Levantamento parasitológico realizado em munícipes do interior do estado de São Paulo (Brasil) entre os anos de 1957 a 1986

Parasitism caused by protozoa and helminths is a serious public health problem, affecting millions of individuals worldwide, especially in underdeveloped and developing countries. From this perspective, a parasitological survey was conducted in 37 cities in the interior of the state of São Paulo. This study focused mainly on old places such as schools and rural and urban health units in the interior of the State of São Paulo between 1957 and 1986. The objective of this study was to conduct a comprehensive survey on the data found to diagnose the occurrence of parasitic diseases in the city. Population at that time, according to their rural and urban origin, age and gender. Thus, the proposal is to make the generated data available to all interested parties in an organized and systematized manner and to discuss the reality faced by the population regarding the current public policies in Brazil relating the sanitary conditions with the occurrence of endoparasites. According to the survey conducted in the municipalities studied, 274,487 occurrences of individuals positive for endoparasites were obtained from 391,633 samples collected. The highest frequency was found in children aged 1 to 10 years with 146,090 cases, accounting for 37,302% of the infected population. The percentage of parasitized individuals decreases with increasing age.

Os quadros de parasitismos causados por protozoários e helmintos constituem sérios problemas de saúde pública, por afetarem milhões de indivíduos em todo o mundo, sobretudo, nos países subdesenvolvidos e em desenvolvimento. Sob esta perspectiva foi realizado um levantamento parasitológico em 37 cidades do interior do Estado de São Paulo. Este estudo contemplou principalmente antigos locais como as escolas e unidades de saúde rurais e urbanas do interior do Estado de São Paulo entre os anos de 1957 e 1986. O objetivo deste trabalho foi realizar um levantamento abrangente nos dados encontrados para diagnosticar a ocorrência de parasitoses na população da época, segundo sua origem rural e urbana, a faixa etária e o gênero. Dessa forma, a proposta é tornar os dados gerados disponíveis a todos os interessados de forma organizada e sistematizada e discutir a realidade enfrentada pela população frente às políticas públicas vigentes no Brasil relacionando as condições sanitárias com a ocorrência de endoparasitoses. Segundo o levantamento realizado nos municípios estudados, obteve-se 274.487 ocorrências de indivíduos positivos para endoparasitas a partir de 391.633 amostras coletadas. A maior frequência foi encontrada em crianças de 1 a 10 anos com 146.090 casos, sendo estes responsáveis por 37.302% da população infectada. A porcentagem de indivíduos parasitados diminui de acordo com o aumento da idade.

Dolor abdominal en paciente con antecedente de diverticulosis colónica / Abdominal pain in a patient with a history of colonic diverticular disease

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Automatic pedicle screw planning using atlas-based registration of anatomy and reference trajectories.

An algorithm for automatic spinal pedicle screw planning is reported and evaluated in simulation and first clinical studies. A statistical atlas of the lumbar spine (N = 40 members) was constructed for active shape model (ASM) registration of target vertebrae to an unsegmented patient CT. The atlas was augmented to include 'reference' trajectories through the pedicles as defined by a spinal neurosurgeon. Following ASM registration, the trajectories are transformed to the patient CT and accumulated to define a patient-specific screw trajectory, diameter, and length. The algorithm was evaluated in leave-one-out analysis (N = 40 members) and for the first time in a clinical study (N = 5 patients undergoing cone-beam CT (CBCT) guided spine surgery), and in simulated low-dose CBCT images. ASM registration achieved (2.0 ± 0.5) mm root-mean-square-error (RMSE) in surface registration in 96% of cases, with outliers owing to limitations in CT image quality (high noise/slice thickness). Trajectory centerlines were conformant to the pedicle in 95% of cases. For all non-breaching trajectories, automatically defined screw diameter and length were similarly conformant to the pedicle and vertebral body (98.7%, Grade A/B). The algorithm performed similarly in CBCT clinical studies (93% centerline and screw conformance) and was consistent at the lowest dose levels tested. Average runtime in planning five-level (lumbar) bilateral screws (ten trajectories) was (312.1 ± 104.0) s. The runtime per level for ASM registration was (41.2 ± 39.9) s, and the runtime per trajectory was (4.1 ± 0.8) s, suggesting a runtime of ~(45.3 ± 39.9) s with a more fully parallelized implementation. The algorithm demonstrated accurate, automatic definition of pedicle screw trajectories, diameter, and length in CT images of the spine without segmentation. The studies support translation to clinical studies in free-hand or robot-assisted spine surgery, quality assurance, and data analytics in which fast trajectory definition is a benefit to workflow.

The onset of dissipation in high-temperature superconductors: magnetic hysteresis and field dependence.

Recently, we showed that the self-field transport critical current, Ic(sf), of a superconducting wire can be defined in a more fundamental way than the conventional (and arbitrary) electric field criterion, Ec = 1 µV/cm. We defined Ic(sf) as the threshold current, Ic,B, at which the perpendicular component of the local magnetic flux density, B⊥, measured at any point on the surface of a high-temperature superconducting tape abruptly crosses over from a non-linear to a linear dependence with increasing transport current. This effect results from the current distribution across the tape width progressively transitioning from non-uniform to uniform. The completion of this progressive transition was found to be singular. It coincides with the first discernible onset of dissipation and immediately precedes the formation of a measureable electric field. Here, we show that the same Ic,B definition of critical currents applies in the presence of an external applied magnetic field, Ba. In all experimental data presented here Ic,B is found to be significantly (10-30%) lower than Ic,E determined by the common electric field criterion of Ec = 1 µV/cm, and Ec to be up to 50 times lower at Ic,B than at Ic,E.

Riesgo cardiovascular en una población adolescente de Timbío, Colombia / Cardiovascular risk in a teenage population in Timbío, Colombia

Resumen Introducción: Las enfermedades cardiovasculares se encuentran entre las primeras causas de muerte a nivel mundial y la evidencia científica sugiere que tienen un origen en edades tempranas, por lo que disminuir desde la adolescencia los riesgos que contribuyen a su aparición es indispensable. Objetivo: Determinar riesgo cardiovascular en la población adolescente de una institución educativa de Timbío, Cauca, 2015 - 2016. Metodología: Estudio cuantitativo, descriptivo, observacional y de corte transversal. Muestra: 100 estudiantes (47 mujeres, 53 hombres), de 10 a 19 años de edad. Se evaluaron variables sociodemográficas, antropométricas, fisiológicas, bioquímicas (glicemia), antecedentes personales, familiares, estilos de vida y uso de anticonceptivos orales. Resultados: Se encontró una mayor prevalencia de riesgo cardiovascular en el grupo etario adolescente (15-18 años) con 84.6%; el género femenino presentó más posibilidad de tener riesgo cardiovascular (OR: 2.8, IC 95% 1.17 - 6.87); el 7% afirmó consumir tabaco regularmente y el 12% son fumadores pasivos. Se obtuvo que el 26% ingiere bebidas alcohólicas, con una mayor prevalencia entre las edades de 15 a 18 años (OR: 19.4, IC 95% 2.45 - 48.11); en cuanto a la actividad física el 79% la practicaba de forma extracurricular. Presentar hábitos alimenticios no saludables genera mayor riesgo cardiovascular (OR: 5.57, IC 95% 1.95 - 15.90). El 67% (n= 67) tiene riesgo cardiovascular. Conclusiones: El género femenino, el grupo adolescente (15-18 años), el consumo de bebidas alcohólicas y hábitos alimenticios no saludables, se asocian con una mayor posibilidad de tener riesgo cardiovascular. Se encontró en un gran porcentaje de la población de estudio riesgo cardiovascular.

Abstract Introduction: Cardiovascular diseases are among the leading causes of death worldwide and scientific evidence suggests that they have an origin at early ages, so that diminishing from adolescence the risks that contribute to its emergence is essential. Objective: To determine cardiovascular risk in the adolescent population of a high school of Timbío, Cauca, 2015 - 2016. Methodology: Quantitative, descriptive, observational and cross-sectional study. Sample: 100 students (47 women, 53 men), from 10 to 19 years old. Sociodemographic, anthropometric, physiological, biochemical variables (glycemia), personal history, family history, lifestyles and use of oral contraceptives were evaluated. Results: A higher prevalence of cardiovascular risk was found in the adolescent age group (15-18 years) with 84.6%; female gender was more likely to have cardiovascular risk (OR: 2.8, 95% CI 1.17 - 6.87); 7% said they use tobacco regularly and 12% are passive smokers. It was obtained that 26% ingested alcoholic beverages, with a higher prevalence between the ages of 15 to 18 years (OR: 19.4, 95% CI 2.45-48.11); In terms of physical activity, 79% practiced it extracurricularly. Presenting unhealthy eating habits generates greater cardiovascular risk (OR: 5.57, 95% CI 1.95 - 15.90). 67% (n = 67) have cardiovascular risk. Conclusions: The female gender, the adolescent group (15-18 years), drink alcoholic beverages and unhealthy eating habits, are associated with a greater possibility of having cardiovascular risk. It was found in a large percentage of the study population cardiovascular risk.

Current distribution across type II superconducting films: a new vortex-free critical state.

The current distribution across the thickness of a current-carrying rectangular film in the Meissner state was established long ago by the London brothers. The distribution across the width is more complicated but was later shown to be highly non-uniform, diverging at the edges. Accordingly, the standard view for type II superconductors is that vortices enter at the edges and, with increasing current, are driven inwards until they self-annihilate at the centre, causing dissipation. This condition is presumed to define the critical current. However we have shown that, under self-field (no external field), the transport critical current is a London surface current where the surface current density equals the critical field divided by λ, across the entire width. The critical current distribution must therefore be uniform. Here we report studies of the current and field distribution across commercial YBa2Cu3 O7 conductors and confirm the accepted non-uniform distribution at low current but demonstrate a radical crossover to a uniform distribution at critical current. This crossover ends discontinuously at a singularity and calculations quantitatively confirm these results in detail. The onset of self-field dissipation is, unexpectedly, thermodynamic in character and the implied vortex-free critical state seems to require new physics.

Malformación cavernomatosa cerebral en mujer presentándose con hemicorea: respuesta al haloperidol / Cerebral cavernous malformation in a woman presenting with hemichorea: Response to haloperidol

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EVALUACIÓN IN VITRO DE LA CAPACIDAD ANTIMICROBIANA DEL ACEITE ESENCIAL DE ENELDO -Anethum graveolens- COMO INHIBIDOR DEL CRECIMIENTO DE Staphylococcus aureus, COLIFORMES Y HONGOS PRESENTES EN LA CARNE DE TRUCHA / IN VITRO EVALUATION OF THE ANTIMICROBIAL CAPACITY OF THE ESSENTIAL OIL OF DILL -Anethum graveolens- AS A GROWTH INHIBITOR OF Staphylococcus aureus, COLIFORMS AND FUNGI FOUND IN TROUT MEAT

El aceite esencial de eneldo tiene propiedades antimicrobianas y antifungicas, por lo que puede ser utilizado para evitar el deterioro de los alimentos. En esta investigación se evaluó la capacidad inhibitoria del aceite esencial de eneldo sobre Staphylococcus aureus, coliformes y hongos presentes en la carne de trucha (Oncorhynchus mykiss), utilizando 50 y 100 pL de aceite esencial. Se evaluaron diferentes condiciones de extracción del aceite esencial mediante el método de hidrodestilación y se logró un rendimiento máximo en base seca de 1,32% utilizando una relación 1:5 de agua y material vegetal durante 90 minutos. Al evaluar la capacidad antimicrobiana, el mayor efecto inhibitorio se obtuvo al aplicar 100 pL de aceite esencial de eneldo en cultivos de Staphylococcus aureus, coliformes fecales, coliformes totales y hongos, evidenciándose un mayor halo de inhibición para coliformes totales.

Dill essential oil has antimicrobial and antifungal properties; therefore it can be used in food to avoid deterioration. In this research, the inhibitory capacity of dill essential oil on Staphylococcus aureus, coliforms and fungi present in trout meat (Oncorhynchus mykiss) was evaluated by using 50 and 100 pL of essential oil. In addition, the different conditions of essential oil extraction were evaluated by the hydrodistillation method, yielding a maximum dry basis yield ofl.32%, using a water-plant ratio of 1:5, during 90 minutes. Antimicrobial capacity was evaluated obtaining greater inhibitory effect when applying 100 pL of dill essential oil in cultures of Staphylococcus aureus, fecal coliforms, total coliforms and fungi, evidencing a greater halo of inhibition for total coliforms.

Market assessment of tuberculosis diagnostics in China in 2012.

OBJECTIVE: To assess the 2012 served available market for tuberculosis (TB) diagnostics in China in the sector served by the China Centre for Disease Control and Prevention (CDC) and the hospital sector in China, including both designated TB hospitals and general hospitals. DESIGN: Test volumes and unit costs were assessed for tuberculin skin tests, interferon-gamma release assays (IGRAs), smear microscopy, serology, cultures, speciation tests, nucleic-acid amplification tests (NAATs), drug susceptibility tests and adenosine-deaminase tests (ADA). Data were obtained from electronic databases (CDC sector) and through surveys (hospital sector), and were estimated for the two sectors and for the country as a whole. Test costs were estimated by staff at China CDC, and using published literature. RESULTS: In 2012, the China CDC and hospital sectors performed a total of 44 million TB diagnostic tests at an overall value of US$294 million. Tests used by the CDC sector were smear microscopy, solid and liquid culture and DST, while the hospital sector also used IGRAs, NAATs, ADA and serology. The hospital sector accounted for 76% of the overall test volume and 94% of the market value. CONCLUSION: China has a very large TB diagnostic market that encompasses a wide range of diagnostic tests, with the majority being performed in Chinese hospitals.

Market assessment of tuberculosis diagnostics in India in 2013.

BACKGROUND: India represents a significant potential market for new tests. We assessed India's market for tuberculosis (TB) diagnostics in 2013. METHODS: Test volumes and unit costs were assessed for tuberculin tests, interferon-gamma release assays, sputum smear microscopy, serology, culture, speciation testing, nucleic-acid amplification tests (i.e., in-house polymerase chain reaction, Xpert(®) MTB/RIF, line-probe assays) and drug susceptibility testing. Data from the public sector were collected from the Revised National TB Control Programme reports. Private sector data were collected through a survey of private laboratories and practitioners. Data were also collected from manufacturers. RESULTS: In 2013, India's public sector performed 19.2 million tests, with a market value of US$22.9 million. The private sector performed 13.6 million tests, with a market value of US$60.4 million when prices charged to the patient were applied. The overall market was US$70.8 million when unit costs from the ingredient approach were used for the 32.8 million TB tests performed in the entire country. Smear microscopy was the most common test performed, accounting for 25% of the overall market value. CONCLUSION: India's estimated market value for TB diagnostics in 2013 was US$70.8 million. These data should be of relevance to test developers, donors and implementers.

Carcinoma sebáceo asociado al síndrome de Muir-Torre: a propósito de un caso / Sebaceous carcinoma associated with Muir-Torre syndrome: report of a case

El Carcinoma Sebáceo (CS) es una neoplasia maligna, poco frecuente, formada por células que muestran una diferenciación hacia el epitelio sebáceo. Generalmente, se presenta en promedio a los 70 años de edad, es más frecuente en mujeres y principalmente en raza asiática. Presentamos el caso de una paciente de sexo femenino de 69 años, con antecedentes familiares de múltiples cánceres, cáncer de mama y la aparición de numerosos adenomas y carcinomas sebáceos, cuadro compatible con un Síndrome de Muir-Torre (SMT). El 75% de los CS se localizan en la región ocular y el 25% es de ubicación extra-ocular. El de ubicación ocular, se caracteriza por un comportamiento agresivo, con diseminación directa y alto potencial de metástasis regional y a distancia. Los tumores extraoculares generalmente son menos agresivos y se localizan principalmente en cabeza y cuello. La patogénesis es incierta, pero los procesos inflamatorios crónicos, la radiación ultravioleta y la radioterapia favorecerán su desarrollo. El CS es un tumor versátil, que se presenta con diferentes aspectos clínicos y distintos patrones histológicos de crecimiento, que retardan el diagnóstico definitivo. El CS es uno de los marcadores cutáneos diagnósticos del SMT, que es una enfermedad genética asociada a neoplasias viscerales. Por lo tanto, los pacientes con CS deben ser cuidadosamente valorados, realizándose una historia oncológica personal y familiar adecuada. El tratamiento de elección es la cirugía con márgenes amplios.

The Sebaceous Carcinoma (SC) is an uncommon malignant tumor formed by cells that show differentiation toward sebaceous epithelium. It usually occurs in women of average at 70 years of age. We report a case of a 69 years old female with a family history of multiples cancer, breast cancer and the emergence of multiple sebaceous adenomas and carcinomas, features consistent with Syndrome Muir Torre (SMT). The 75% of the SC are located in the ocular region and the 25% rest presents extraocular location. The eye location is characterized by aggressive behavior, with direct extension and high potential for regional and distant metastases. Extraocular are generally less aggressive tumors and are located mainly in the head and neck. The pathogenesis is unclear, but chronic inflammatory processes, ultraviolet radiation and radiation will favor its development. The SC is a versatile tumor that presents with different clinical and histological different growth patterns, which retard the definitive diagnosis. SC is one of the cutaneous diagnostic markers of SMT, which is a genetic disease associated with visceral neoplasms. They are carefully assessed, performing a proper personal and family cancer history. The treatment of choice is the surgery with wide margins.

Bryophytes in fragments of Terra Firme forest on the great curve of the Xingu River, Pará state, Brazil.

Microclimatic conditions of tropical forest favour the high richness of bryophytes, which by being sensitive to environmental changes, are important indicators of habitat conditions. The aim of this study was to determine the richness and species composition of the bryophyte flora in fragments of terra firme forest on the great curve of the Xingu River, Pará state, Brazil. The collections were made in August and September 2012 in 14 fragments, in which were installed two plots per fragment, one at the edge and one inside, measuring 10 × 10 m each. The results showed 77 species in 45 genera and 18 families. Lejeunea setiloba Spruce and Marchesinia brachiata (Sw.) Schiffn. are new records for Pará state. The richness families in this study were the ones typically found in tropical forest surveys. A high richness of rare species in comparison to common ones, a pattern usually observed for plants in tropical forests was not reported in this study, probably due to historical fragmentation and disturbance in the area. The richness and species composition were determined mainly by the physiognomic characteristics of the studied forest fragments.

Bryophytes in fragments of Terra Firme forest on the great curve of the Xingu River, Pará state, Brazil 1 Part of Master's Dissertation of the first author / Briófitas em fragmentos florestais de terra firme na região da Volta Grande do Xingu, Pará, Brasil

Microclimatic conditions of tropical forest favour the high richness of bryophytes, which by being sensitive to environmental changes, are important indicators of habitat conditions. The aim of this study was to determine the richness and species composition of the bryophyte flora in fragments of terra firme forest on the great curve of the Xingu River, Pará state, Brazil. The collections were made in August and September 2012 in 14 fragments, in which were installed two plots per fragment, one at the edge and one inside, measuring 10 × 10 m each. The results showed 77 species in 45 genera and 18 families. Lejeunea setiloba Spruce and Marchesinia brachiata (Sw.) Schiffn. are new records for Pará state. The richness families in this study were the ones typically found in tropical forest surveys. A high richness of rare species in comparison to common ones, a pattern usually observed for plants in tropical forests was not reported in this study, probably due to historical fragmentation and disturbance in the area. The richness and species composition were determined mainly by the physiognomic characteristics of the studied forest fragments.

As condições microclimáticas das florestas tropicais favorecem elevada riqueza de briófitas, que por serem sensíveis às alterações ambientais, são importantes indicadoras das condições dos habitats. O objetivo deste trabalho foi determinar a riqueza e a composição florística da brioflora de fragmentos florestais de terra firme na região da Volta Grande do Xingu, Pará, Brasil. As coletas foram realizadas em Agosto e Setembro de 2012, em 14 fragmentos e em cada um destes foram plotadas duas parcelas, uma na borda e outra no interior, medindo 10 × 10 m (cada). Foram registradas 77 espécies, distribuídas em 45 gêneros e 18 famílias. Lejeunea setiloba Spruce e Marchesinia brachiata (Sw.) Schiffn. são novos registros para o Pará. As famílias mais ricas neste estudo foram aquelas tipicamente encontradas em levantamentos em florestas tropicais. A elevada riqueza de espécies raras em comparação às comuns, padrão comumente reportado para plantas em florestas tropicais, não foi observada, provavelmente devido ao histórico de fragmentação e distúrbios na área de estudo. A riqueza e a composição de espécies foram determinadas principalmente pelas características fisionômicas dos fragmentos estudados.