Forest disturbance and recovery in Peruvian Amazonia.

Amazonian forests function as biomass and biodiversity reservoirs, contributing to climate change mitigation. While they continuously experience disturbance, the effect that disturbances have on biomass and biodiversity over time has not yet been assessed at a large scale. Here, we evaluate the degree of recent forest disturbance in Peruvian Amazonia and the effects that disturbance, environmental conditions and human use have on biomass and biodiversity in disturbed forests. We integrate tree-level data on aboveground biomass (AGB) and species richness from 1840 forest plots from Peru's National Forest Inventory with remotely sensed monitoring of forest change dynamics, based on disturbances detected from Landsat-derived Normalized Difference Moisture Index time series. Our results show a clear negative effect of disturbance intensity tree species richness. This effect was also observed on AGB and species richness recovery values towards undisturbed levels, as well as on the recovery of species composition towards undisturbed levels. Time since disturbance had a larger effect on AGB than on species richness. While time since disturbance has a positive effect on AGB, unexpectedly we found a small negative effect of time since disturbance on species richness. We estimate that roughly 15% of Peruvian Amazonian forests have experienced disturbance at least once since 1984, and that, following disturbance, have been increasing in AGB at a rate of 4.7 Mg ha-1 year-1 during the first 20 years. Furthermore, the positive effect of surrounding forest cover was evident for both AGB and its recovery towards undisturbed levels, as well as for species richness. There was a negative effect of forest accessibility on the recovery of species composition towards undisturbed levels. Moving forward, we recommend that forest-based climate change mitigation endeavours consider forest disturbance through the integration of forest inventory data with remote sensing methods.

Los bosques amazónicos son reservorios y sumideros de carbono, contribuyendo a la mitigación del cambio climático. Si bien experimentan perturbaciones, el efecto de estas en la biomasa y biodiversidad a través del tiempo no ha sido evaluado a gran escala. En este estudio, evaluamos el grado de perturbación forestal reciente en la Amazonía peruana y los efectos de las perturbaciones, condiciones ambientales y actividad antrópica sobre la biomasa y la biodiversidad en bosques perturbados. Los datos de biomasa aérea y riqueza de especies forestales provenientes de 1,840 subparcelas del Inventario Nacional Forestal y de Fauna Silvestre (INFFS) se analizaron en conjunto con la información de detección de cambios de cobertura forestal derivadas de perturbaciones detectadas a partir de series de tiempo de índices de diferencia de humedad normalizados (NDMI) a partir de imágenes Landsat. Nuestros resultados muestran un claro efecto negativo de la intensidad de las perturbaciones sobre la riqueza de especies arbóreas. Este efecto también fue observado en los valores de recuperación de biomasa aérea y riqueza de especies arbóreas hacia niveles no perturbados, así como en la recuperación de la composición florística. El tiempo transcurrido desde la perturbación tuvo un efecto mayor sobre la biomasa aérea que sobre la riqueza de especies. Mientras el tiempo desde una perturbación forestal tuvo un efecto positivo sobre la biomasa área, se observó un pequeño efecto negativo sobre la riqueza de especies. Estimamos que aproximadamente el 15% de los bosques en la Amazonía peruana han experimentado una perturbación al menos una vez desde 1984, y que, tras esta, han aumentado en biomasa aérea en una tasa de 4.7 Mg ha−1 año−1 durante los primeros 20 años posteriores al evento de perturbación. Además, el efecto positivo de la cubierta forestal circundante fue evidente tanto para la biomasa aérea como para su recuperación hacia niveles no perturbados, así como para los valores de riqueza de especies. La accesibilidad a bosques tuvo un efecto negativo en la recuperación de la composición de especies hacia niveles no perturbados. Recomendamos que los esfuerzos de mitigación de cambio climático basados en bosques tengan en cuenta las perturbaciones forestales mediante el análisis integrado de información de inventarios forestales con métodos de teledetección.

Reporte del uso de infliximab en psoriasis generalizada y resistente / Use of infl iximab in refractory and extended psoriasis report

La psoriasis es una enfermedad inflamatoria hiperproliferativa de causa desconocida y multifactorial. Es la primera causa de consulta y hospitalización en el Servicio de Dermatología del Hospital Nacional Guillermo Almenara Irigoyen (HNGAI). Se presenta un caso de tratamiento exitoso con infliximab en un paciente con psoriasis extensa y resistente a terapia convencional.

Psoriasis is an infl ammatory hiperproliferative disease of unknown cause and polygenic factors. Is the most common disease among patientsrequiring hospitalization in Dermatology Service of Guillermo Almenara Irigoyen Hospital (GAIH). Here we report on the successful treatmentwith infl iximab in a patient with refractory and extensive psoriasis.

Síndrome de Stevens-Johnson y necrólisis epidérmica tóxica: experiencia clínica en el Hospital Nacional Guillermo Almenara Irigoyen, Lima - Perú / Stevens-Johnson Syndrome and toxic epidermal necrolysis: clinical experience at the Hospital Nacional Guillermo Almenara Irigoyen, Lima-Peru

Objetivo: Describir las características clínicas de un grupo de pacientes diagnosticados de síndrome de Stevens-Johnsons (SSJ) y necrólisis epidérmica tóxica (NET). Material y métodos: Estudio retrospectivo, transversal y descriptivo realizado en el Hospital Nacional Guillermo Almenara Irigoyen entre junio de 2004 y mayo del 2007. Se revisó las historias clínicas de los casos hospitalizados, recogiendo la información sobre drogas responsables, tratamiento y resultado final. Resultados: Se estudiaron siete pacientes, cinco con diagnóstico de NET, uno con SSJ y uno con síndrome SSJ-NET. Cinco pacientes fueron mujeres y dos varones, con una edad media de 47 años.Los fármacos asociados fueron los anticonvulsivantes (fenitoína y lamotrigina) en tres pacientes, metamizol en dos, cotrimoxazol en uno y fluconazol también en uno. La mucosa oral fue afectada en todos los casos, la mucosa genital en cuatro y la mucosa conjuntival en tres. El tratamiento de elección fueron los corticoides en seis pacientes y se inicio de forma rápida en cuatro, evolucionando con mínimas complicaciones y solo uno de ellos presento secuelas oculares. Solo hubo un deceso en este grupo. Conclusiones: El SSJ y la NET en nuestros casos fueron causados principalmente por anticonvulsivantes y metamizol, fueron tratados en su mayoría con corticoides sistémicos. Drogas de uso creciente como fluconazol y lamotrigina también deben considerarse entre los medicamentos de riesgo.

Fibrohistiocitoma maligno / Malignant fibrous histiocytoma

El fibrohistiocitoma maligno ha sido considerado el sarcoma de los tejidos blandos más común, durante la adultez media y tardía. Es frecuente en tejidos profundos y músculo estriado, y raro como tumor cutáneo. Reportamos el caso de un varón de 31 años, con una lesión tumoral de seis meses en piel de la zona iliaca derecha, que muestra en el estudio histopatológico un fuerte infiltrado de células neoplásicas indiferenciadas, diagnosticándose fibrohistiocitoma maligno, y detectándose signos de metástasis ósea. Se remarca la utilidad del estudio inmunohistoquímico para la tipificación de tumores con células neoplásicas indiferenciadas.

Hipoqueratosis palmar circunscrita: reporte de un primer caso / Circumscribed palmar hypokeratosis: report of a clinical case

Una paciente de 63 años de edad, presentó por seis años una placa deprimida circunscrita en la región tenar de palma derecha, la cual va incrementando paulatinamente de tamaño. Histológicamente se observó una disminución abrupta en el grosor de la capa córnea, con un área central de estrato córneo adelgazado y una capa granular disminuida; no se evidenció inflamación. La paciente tuvo muchos diagnósticos y tratamientos previos con corioterapia tópica y calcitriol, sin obtener mejoría evidente. Es el primer caso reportado en nuestro país de esta reciente enfermedad llamada hipoqueratosis palmar o plantar circunscrita, que correspondió a lo descrito en la literatura como propio de mujeres de edad mayor y con evolución crónica y persistente. Actualmente recién está siendo descrita y probando nuevos esquemas terapéuticos.

Non-chromatographic speciation of toxic arsenic in fish.

A rapid, sensitive and economic method has been developed for the direct determination of toxic species of arsenic present in fish and mussel samples. As(III), As(V), dimethylarsinic acid (DMA), and monomethylarsonic acid (MMA) were determined by hydride generation-atomic fluorescence spectrometry using a series of proportional equations without the need of a chromatographic previous separation. The method is based on the extraction of arsenic species from fish through sonication with HNO(3) 3moll(-1) and 0.1% (m/v) Triton and washing of the solid phase with 0.1% (m/v) EDTA, followed by direct measurement of the corresponding hydrides in four different experimental conditions. The limit of detection of the method was 0.62ngg(-1) for As(III), 2.1ngg(-1) for As(V), 1.8ngg(-1) for MMA and 5.4ngg(-1) for DMA, in all cases expressed in terms of sample dry weight. The mean relative standard deviation values (R.S.D.) in actual sample analysis were: 6.8% for As(III), 10.3% for As(V), 8.5% for MMA and 7.4% for DMA at concentration levels from 0.08mgkg(-1) As(III) to 1.3mgkg(-1) DMA. Recovery studies provided percentages greater than 93% for all species in spiked samples. The analysis of SRM DORM-2 and CRM 627 certified materials evidenced that the method is suitable for the accurate determination of arsenic species in fish.

Multicommutation as an environmentally friendly analytical tool in the hydride generation atomic fluorescence determination of tellurium in milk.

The aim of this study is to show the advantages of the emerging multicommutation methodology based on the use of solenoid valves for Te determination in milk by hydride generation atomic fluorescence spectrometry (HG-AFS). The delivery of a series of alternating sequential insertions of small volumes of samples and reagents gives rise to new hydrodynamic processes and exciting analytical potentials by controlling the time of flow through the on/off-switched solenoid valves. This drastically reduces the reagent consumption by a factor of 4 and the generation of effluents (590 mL h(-1) instead of 750 mL h(-1) generated by the continuous-mode measurement) and also provides an improvement in the laboratory productivity by an increase of the sample throughput (85 h(-1) compared to 20 h(-1) found in the continuous mode). So, multicommutation is an environmentally and economically sustainable alternative to the methodology based on continuous measurements. The multicommutation-based method developed was applied to tellurium determination in commercially available milk samples; a calibration range of 0.0-0.5 ng mL(-1) and a detection limit of 0.20 ng L(-1) with average relative standard deviation of 2.1% were found. Comparable results were obtained for a series of samples using both continuous and multicommutation HG-AFS modes.

Determination of As, Sb, Se, Te and Bi in milk by slurry sampling hydride generation atomic fluorescence spectrometry.

A simple and fast analytical procedure has been developed for the determination of As, Sb, Se, Te and Bi in milk samples by hydride generation atomic fluorescence spectrometry (HG-AFS). Samples were treated with aqua regia for 10min in an ultrasound water bath and pre-reduced with KBr for total Se and Te determination or with KI and ascorbic acid for total As and Sb, the determination of Bi being possible in all with or without pre-reduction. Slurries of samples, in the presence of antifoam A, were treated with NaBH(4) in HCl medium to obtain the corresponding hydrides, and AFS measurements were processed in front of external calibrations prepared and measured in the same way as samples. Results obtained by the developed procedure compare well with those found after microwave-assisted complete digestion of samples. The proposed method is simple and fast, and only 1ml of milk is needed. The values obtained for detection limit are 2.5, 1.6, 3, 6 and 7ngl(-1) for As, Sb, Se, Te and Bi respectively in the diluted samples, with average relative standard deviation values of 3.8, 3.1, 1.9, 6.4 and 1.2% for three independent analysis of a series of commercially available samples of different origin. Data found in Spanish market samples varied from 3.2+/-0.3 to 11.3+/-0.2ngg(-1) As, from 3.1+/-0.2 to 11.6+/-0.4ngg(-1) Sb, from 10.7+/-0.5 to 25.5+/-0.4ngg(-1) Se, from 0.9+/-0.2 to 9.4+/-0.6ngg(-1) Te and from 11.5+/-0.1 to 27.7+/-0.4ngg(-1) Bi.

Determination of ultratrace bismuth in milk samples by atomic fluorescence spectrometry.

A sensitive procedure was developed for determination of bismuth (Bi) in milk samples by hydride generation atomic fluorescence spectrometry (HG-AFS) after microwave-assisted sample digestion with HNO3 and H2O2. The method provides a sensitivity of 1832 fluorescence units (ng/mL) with a detection limit of 0.01 ng/mL, which corresponds to 20 pg absolute limit of detection, equivalent to 0.50 ng/g in the original sample. Application of the methodology to cow milk samples from the Spanish market showed the presence of Bi at a concentration of 11.8-28.8 ng/g, which compared well with data obtained after dry ashing of samples and with data obtained by inductively coupled plasma-mass spectrometry after microwave-assisted digestion.

Determination of arsenic and antimony in milk by hydride generation atomic fluorescence spectrometry.

A highly sensitive procedure has been developed for total arsenic and antimony determination in milk samples by hydride generation atomic fluorescence spectrometry after microwave-assisted sample digestion. The discrete introduction of 2 ml of digested sample in the automated continuous flow hydride generation system allows us to reduce drastically the sample and HCl consume and to determine several elements from a same sample digestion. The method provides detection limits of 0.006 and 0.003 ng ml(-1), a sensitivity of 2390 and 2840 fluorescence units per ng ml(-1) for As and Sb respectively, and average relative standard deviation of 2.3% for As and 4.8% for Sb. The analysis of cow milk samples, obtained from the Spanish market evidenced the presence of As at concentration levels from 3.4 to 11.6 ng g(-1) and Sb levels from 3.5 to 11.9 ng g(-1), thus in a proportion near to 1:1, which is in contrast with the 10:1 natural ratio between As and Sb and could evidence the effect of the introduction of new alloys and polymer materials in the industrial process of milk. The method was validated by the comparison of data found for commercial samples by using the proposed procedure and reference methods based on dry-ashing and AFS, and microwave-assisted digestion and inductively coupled plasma mass spectrometry determination.