RESUMO

Los pólipos pilosos nasofaríngeos son tumores benignos poco frecuentes. Se presenta el caso de esta patología en una paciente recién nacida, quien presentó cianosis y dificultad respiratoria por obstrucción de la vía aérea superior, durante las primeras 24 horas de vida. La paciente requirió maniobras de reanimación e intubación endotraqueal. Estudios diagnósticos confirmaron la presencia de una masa en la pared lateral de la faringe. Se realizó la extirpación quirúrgica exitosa con evolución satisfactoria de la paciente

Nasopharyngeal hairy polyps are rare benign tumors. We present a newborn case with a hairy polyp mass causing cyanosis and respiratory distress due to obstruction of the upper airway during the first 24 hours of life. The patient required resuscitation and endotracheal intubation. Diagnostic studies confirmed the presence of a mass in the lateral pharyngeal wall. Surgical treatment and removal of the mass was performed with satisfactory evolution of the patient

Assuntos

RESUMO

Nasopharyngeal hairy polyps are rare benign tumors. We present a newborn case with a hairy polyp mass causing cyanosis and respiratory distress due to obstruction of the upper airway during the first 24 hours of life. The patient required resuscitation and endotracheal intubation. Diagnostic studies confirmed the presence of a mass in the lateral pharyngeal wall. Surgical treatment and removal of the mass was performed with satisfactory evolution of the patient.

Los pólipos pilosos nasofaríngeos son tumores benignos poco frecuentes. Se presenta el caso de esta patología en una paciente recién nacida, quien presentó cianosis y dificultad respiratoria por obstrucción de la vía aérea superior, durante las primeras 24 horas de vida. La paciente requirió maniobras de reanimación e intubación endotraqueal. Estudios diagnósticos confirmaron la presencia de una masa en la pared lateral de la faringe. Se realizó la extirpación quirúrgica exitosa con evolución satisfactoria de la paciente.

Assuntos

RESUMO

The highland forests of tropical regions are highly vulnerable to climate change because changes in soil organic quality due to the increased soil water deficit conditions through rising temperatures. Several authors have reported that labile molecules dominate soil organic matter at higher elevations, and it is therefore more vulnerable to the rising temperatures associated with climate change. The objective of the present study was to analyze the effect of interaction between the chemical composition of organic matter derived from the dominant plant species and the metabolism of microbial community along an elevational gradient in a highland forest in Central Mexico. The study compared three vegetation-soil systems that represent three different elevational levels: Alnus-system (3100 m.a.s.l.), Abies-system (3500 m.a.s.l.) and Pinus-system (3700 m.a.s.l.). The SOM produced in the lowest site is more recalcitrant (i.e., higher Alkyl:O-Alkyl ratio) as a result of the lower water availability than in the highest site. The results of Threshold Elemental RatioC:N (TERC:N) and TERC:P for the organic layer were lower than their C:N and C:P ratios in the organic layer, supporting that the microbial community of the organic layer in the site of lowest elevation must be limited by the carbon source, rather than by N and P. However, these results were not found in the mineral soil, suggesting that the drivers of organic matter decomposition differ between the organic layer and the mineral soil. As a conclusion, our results suggest that the chemical recalcitrance of organic matter (at the lowest site) and temperature (at the highest site) reduce the microbial metabolic activity in the forest floor. Integrated study of plant-derived organic material and the microbial metabolism of the forest floor is therefore required to achieve a full understanding of the vulnerability of tropical mountain ecosystems to climate change.

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RESUMO

BACKGROUND: Litter decomposition is a key process in the functioning of forest ecosystems, because it strongly controls nutrient recycling and soil fertility maintenance. The interaction between the litter chemical composition and the metabolism of the soil microbial community has been described as the main factor of the decomposition process based on three hypotheses: substrate-matrix interaction (SMI), functional breadth (FB) and home-field advantage (HFA). The objective of the present study was to evaluate the effect of leaf litter quality (as a direct plant effect, SMI hypothesis), the metabolic capacity of the microbial community (as a legacy effect, FB hypothesis), and the coupling between the litter quality and microbial activity (HFA hypothesis) on the litter decomposition of two contiguous deciduous oak species at a local scale. METHODS: To accomplish this objective, we performed a litterbag experiment in the field for 270 days to evaluate mass loss, leaf litter quality and microbial activity in a complete factorial design for litter quality and species site. RESULTS: The litter of Quercus deserticola had higher rate of decomposition independently of the site, while the site of Quercus castanea promoted a higher rate of decomposition independently of the litter quality, explained by the specialization of the soil microbial community in the use of recalcitrant organic compounds. The Home-Field Advantage Index was reduced with the decomposition date (22% and 4% for 30 and 270 days, respectively). DISCUSSION: We observed that the importance of the coupling of litter quality and microbial activity depends on decomposition stage. At the early decomposition stage, the home-advantage hypothesis explained the mass loss of litter; however, in the advanced decomposition stage, the litter quality and the metabolic capacity of the microbial community can be the key drivers.

RESUMO

The effect of precipitation regime on the C cycle of tropical forests is poorly understood, despite the existence of models that suggest a drier climate may substantially alter the source-sink function of these ecosystems. Along a precipitation regime gradient containing 12 mature seasonally dry tropical forests growing under otherwise similar conditions (similar annual temperature, rainfall seasonality, and geological substrate), we analyzed the influence of variation in annual precipitation (1240 to 642 mm) and duration of seasonal drought on soil C. We investigated litterfall, decomposition in the forest floor, and C storage in the mineral soil, and analyzed the dependence of these processes and pools on precipitation. Litterfall decreased slightly - about 10% - from stands with 1240 mm yr(-1) to those with 642 mm yr(-1), while the decomposition decreased by 56%. Reduced precipitation strongly affected C storage and basal respiration in the mineral soil. Higher soil C storage at the drier sites was also related to the higher chemical recalcitrance of litter (fine roots and forest floor) and the presence of charcoal across sites, suggesting an important indirect influence of climate on C sequestration. Basal respiration was controlled by the amount of recalcitrant organic matter in the mineral soil. We conclude that in these forest ecosystems, the long-term consequences of decreased precipitation would be an increase in organic layer and mineral soil C storage, mainly due to lower decomposition and higher chemical recalcitrance of organic matter, resulting from changes in litter composition and, likely also, wildfire patterns. This could turn these seasonally dry tropical forests into significant soil C sinks under the predicted longer drought periods if primary productivity is maintained.

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