bluuebunny/crossref_metadata_2025_split huggingface dataset:
Skin damage and mitochondrial dysfunction after acute ultraviolet B irradiation: relationship with nitric oxide production
Authors: Maglio Daniel H. Gonzalez , Paz Mariela L. , Ferrari Alejandro , Weill Federico S. , Czerniczyniec Analía , Leoni Juliana , Bustamante Juanita 
Published: November 2005

Background: Ultraviolet (UV) radiation is the main environmental carcinogen. It is able to induce injury in the keratinocytes, which triggers mechanisms in order to protect the skin against molecular alterations that may lead to the development of skin cancer. UVB is capable of producing genotoxic damage, directly or indirectly through reactive oxygen species, inducing DNA alterations and mutations. UVB radiation has also been associated with the generation of nitric oxide (NO), which is able to induce many physiological and physiopathological processes. The aim of the current study was to investigate the effect of UVB irradiation in hairless mice skin.Methods: We evaluated the effect of an acute dose (200 mJ/cm2) of UVB irradiation correlating with histological alterations, nitric oxide synthase expression and activity, mitochondrial respiratory function, superoxide anion production and lipid peroxidation, 0, 6, 17 and 24 h post‐irradiation treatment.Results: Morphological analysis showed disruption of the epidermal stratum corneum and basale after UVB irradiation. The results indicated that skin UVB irradiation was associated with an increased cytosolic inducible nitric oxide synthase (iNOS) expression, inversely related to lipid peroxidation processes. An increase in mitochondrial superoxide anion (O2•−) and NO production 17 h post‐irradiation was correlated with a mitochondrial dysfunction, all of them integrating the skin response to acute UVB irradiation.Conclusions:UVB irradiation of the skin produces morphological alterations as a consequence of the induction of molecular mechanisms associated with mitochondrial respiratory dysfunction and O2•− production, probably mediated by the increased mitochondrial NO production. On the other hand lipid peroxidation decrease inversely correlates with cytosolic iNOS expression, suggesting a protective role for the inflammatory response.
Experimental phytophotodermatitis
Authors: Gonçalves N. E. L. , de Almeida H. L. , Hallal E. C. , Amado M. 
Published: November 2005

Background/Aims: Phytophotodermatitis (PPD) is defined as a phototoxic reaction of the skin after contact with substances derived from plants and subsequent exposure to sunlight. It is a frequent disease in our outpatient clinics during summer because of contact with Tahitian lemon. Our objectives were to experimentally reproduce PPD in rats, to identify whether PPD is induced by minimal exposure periods to sunlight, to find what kinds of lemons and which parts of the lemon (the fruit juice or the peel juice) may trigger the disease; to know whether the use of sunblock prevents the reaction; and to perform light microscopy of the lesions to describe their histology.Methods: Adult rats (Rattus norwegicus), three in each experiment, were used. After painting the rats with the fruit juice or the peel juice they were exposed to sunlight for 2.5, 5, 7.5, and 10 min. Tahitian and Sicilian lemons were used in the experiments. Biopsies with 3‐mm punches of different times of exposure were performed.Results: The peel juice of both lemons reproduced PPD, which was clinically evident after 48 h. When the peel juice was alone applied there was no reaction; moreover, exposure to sunlight alone triggered no reaction. Two and a half minutes of exposure time was sufficient to induce phototoxic reaction, which was time dependent (the longer the exposure the more intense the reaction). Histopathological studies showed epithelial time‐dependent vacuolar degeneration. The use of sunblock diminished the intensity of the reaction but did not prevent it.Conclusion: PPD can be reproduced in an animal model. It may be caused by the peel juice of Tahitian and Sicilian lemon. Because of an extremely short time of exposure (2.5 min) is sufficient to induce PPD it is necessary to alert the population, of the need for caution when handling lemons, especially outdoors despite using sunblock.
Sexual limitations in people living with Parkinson's disease
Authors: Mott Sarah , Kenrick Marita , Dixon Miriam , Bird Graham 
Published: November 2005

Objectives:  To explore disease sequelae and usage of support services in people living with Parkinson's disease (PD). Methods:  A 31‐item survey was administered to a convenience sample of people with PD recruited through Parkinson's NSW Inc. and its support groups. Results:  Four hundred and forty‐four responses were received. Sexual limitations were reported by 73.5% of people with PD. Additionally, respondents indicated that health professionals did not necessarily understand what it is like to live with the disease. Conclusions:  Movement problems are most often presented as the major sequelae of PD. This study shows that for a large proportion of sufferers, sexual limitations are an issue. Additionally, it is important for health professionals to provide ample opportunity for the discussion of these difficulties.
Individual differences in the experience of burden in caring for relatives with dementia: role of personality and mastery
Authors: Helmes Edward , Green Bev , Almeida Osvaldo P 
Published: November 2005

Objective:  We explored individual differences in caregiver outcome according to the personality and behavioural style of the carer. Current models of caregiver burden fail to consider such factors. Methods:  This cross‐sectional, exploratory study used carer variables of personality traits and mastery and patient variables of cognitive, functional and neurobehavioural status to predict scores on an established measure of burden in a sample of 51 people with dementia and their carers. Results:  Hierarchical multiple regression showed a significant association between behavioural disturbance and neuroticism and burden, but not with mastery. Conclusions:  The primary findings in this study are that models of caregiver outcome need to take an individual differences perspective in accounting for caregiver mental health risk factors: personality characteristics do play a part in the way caregivers manage this difficult role.
Accommodation options in later life: retirement village or community living?
Authors: Gardner Ian L , Browning Colette , Kendig Hal 
Published: November 2005

Objectives:  To assess retirement villages as an accommodation option for older people by examining the impact on quality of life of moving to a village. Method:  A cross‐sectional survey of three groups: residents of independent living units of two retirement villages and a group of older people who considered moving but decided to remain living in the community. Results:  The quality of life of all groups at interview was high. However, the village group's overall satisfaction with life, and satisfaction with friendships and social life, was better after moving, whereas the community group were more likely to say that their quality of life was the same or worse since looking at moving to a village. Conclusions:  Retirement villages can be a viable accommodation option in later life and enhance quality of life. The results of this study have implications for government policy, public and private housing providers, and older people.
Effects of Season and Successional Stage on Leaf Area Index and Spectral Vegetation Indices in Three Mesoamerican Tropical Dry Forests1
Authors: Kalacska Margaret E. R. , Sánchez‐Azofeifa G. Arturo , Calvo‐Alvarado Julio C. , Rivard Benoit , Quesada Mauricio 
Published: November 2005

ABSTRACTWe compared plant area index (PAI) and canopy openness for different successional stages in three tropical dry forest sites: Chamela, Mexico; Santa Rosa, Costa Rica; and Palo Verde, Costa Rica, in the wet and dry seasons. We also compared leaf area index (LAI) for the Costa Rican sites during the wet and dry seasons. In addition, we examined differences in canopy structure to ascertain the most influential factors on PAI/LAI. Subsequently, we explored relationships between spectral vegetation indices derived from Landsat 7 ETM+ satellite imagery and PAI/LAI to create maps of PAI/LAI for the wet season for the three sites. Specific forest structure characteristics with the greatest influence on PAI/LAI varied among the sites and were linked to climatic differences. The differences in PAI/LAI and canopy openness among the sites were explained by both the past land‐use history and forest management practices. For all sites, the best‐fit regression model between the spectral vegetation indices and PAI/LAI was a Lorentzian Cumulative Function. Overall, this study aimed to further research linkages between PAI/LAI and remotely sensed data while exploring unique challenges posed by this ecosystem.
The Utility of Spectral Indices from Landsat ETM+ for Measuring the Structure and Composition of Tropical Dry Forests1
Authors: Feeley Kenneth J. , Gillespie Thomas W. , Terborgh John W. 
Published: November 2005

ABSTRACTThere is a growing emphasis on developing methods for quantifying the structure and composition of tropical forests that can be applied over large landscapes, especially for tropical dry forests that are severely fragmented and have a high conservation priority. This study investigates the relationships between various measures of forest structure (annual woody increment, canopy closure, stand density, stand basal area) and composition (tree species diversity, tree community composition) measured in semi‐deciduous tropical dry forests on islands in Lago Guri, Venezuela and three spectral indices derived from Landsat ETM+: Normalized Difference Vegetation Index (NDVI), Infrared Index (IRI), and Mid‐Infrared Index (MIRI). Even though there were significant autocorrelations among spectral indices, there were significant differences in the relationships between spectral indices and forest attributes. IRI was not significantly correlated with any of the structural variables while MIRI was correlated with canopy closure and NDVI values were correlated with canopy closure as well as annual woody increment. NDVI and MIRI were both related to relative tree diversity and all three indices were associated with aspects of tree species composition. Based on the results of this study, it appears that spectral indices, and in particular NDVI, may be useful indicators of forest attributes in tropical dry forest habitats. Further research needs to be undertaken to identify if the results of this study can be applied to other tropical dry forests at a global spatial scale.
Vegetation Structure, Composition, and Species Richness Across a 56‐year Chronosequence of Dry Tropical Forest on Providencia Island, Colombia1
Authors: Ruiz Jorge , Fandiño Maria C. , Chazdon Robin L. 
Published: November 2005

ABSTRACTWe compared vegetation structure and species richness across a 56‐yr chronosequence of six replicated age classes of dry tropical forest on the island of Providencia, Colombia, in the Southwest Caribbean. Stand age classes were determined using sequential, orthorectified panchromatic aerial photos acquired between 1944 and 1996 and Landsat 7 ETM + satellite imagery from 2000. Along the chronosequence we established 59 plots of 2 × 50 m (0.01 ha) to document changes in species richness, basal area, tree height, stem density, and sprouting ability. All woody trees and shrubs >2.5 cm diameter at breast height (DBH) were censused and measured. Although woody species density reached a peak in stands from 32 to 56 yr old, rarefaction analysis showed that species richness increased linearly with stand age and was highest in stands 56 yr old or greater. Nonparametric, abundance‐based estimators of species richness also showed positive and linear associations with age. Basal area and mean tree height were positively associated with age since abandonment, while sprouting ability showed a negative relationship. Our results indicate rapid recovery of woody species richness and structural characteristics along this tropical dry forest chronosequence.
Tropical Dry Forests of Venezuela: Characterization and Current Conservation Status1
Authors: Fajardo Laurie , González Valois , Nassar Jafet M. , Lacabana Pablo , Portillo Q. Carlos A. , Carrasquel Fabián , Rodríguez Jon Paul 
Published: November 2005

ABSTRACTTropical dry forests are located predominantly in the northern portion of Venezuela, above 6°N. Although their potential extent covers ca 400,000 km2 (44% of the land), they currently occupy about 10 percent of this area. The diversity and complexity of Venezuelan dry forests increases from north to south along a gradient of decreasing severity of the dry season. A typical dry forest in Venezuela presents ca 110–170 species of plants from ca 40 to 50 families within an area of approximately 10 ha. Species composition and forest structure, however, are dependent on local landscape conditions (e.g., soil type, topography), and nearby forest types can be very different. Our analysis of five dry forest variants showed a maximum family similarity of 67 percent, although most values fell in the 50–60 percent interval. They are currently considered as one of Venezuela's most threatened ecosystems, but only 5 percent of extant dry forests are included in protected areas; this represents 0.5 percent of their potential extent. It is fundamental to promote the creation of at least 3 or 4 more large protected areas (ca 5000 ha), with different climatic and orographic characteristics, in combination with the recovery of threatened species, the restoration of degraded systems, and the implementation of sustainable development projects. Their apparent high resilience suggests that with the proper management we can restore and maintain the integrity of Venezuelan dry forests.
Diverse Optical and Photosynthetic Properties in a Neotropical Dry Forest during the Dry Season: Implications for Remote Estimation of Photosynthesis1
Authors: Gamon John A. , Kitajima Kaoru , Mulkey Stephen S. , Serrano Lydia , Wright S. Joseph 
Published: November 2005

ABSTRACTUsing optical and photosynthetic assays from a canopy access crane, we examined the photosynthetic performance of tropical dry forest canopies during the dry season in Parque Metropolitano, Panama City, Panama. Photosynthetic gas exchange, chlorophyll fluorescence, and three indices derived from spectral reflectance (the normalized difference vegetation index, the simple ratio, and the photochemical reflectance index) were used as indicators of structural and physiological components of photosynthetic activity. Considerable interspecific variation was evident in structural and physiological behavior in this forest stand, which included varying degrees of foliage loss, altered leaf orientation, stomatal closure, and photosystem II downregulation. The normalized difference vegetation index and the simple ratio were closely related to canopy structure and absorbed radiation for most species, but failed to capture the widely divergent photosynthetic behavior among evergreen species exhibiting various degrees of downregulation. The photochemical reflectance index and chlorophyll fluorescence were related indicators of photosynthetic downregulation, which was not detectable with the normalized difference vegetation index or simple ratio. These results suggest that remote sensing methods that ignore downregulation cannot capture within‐stand variability in actual carbon flux for this diverse forest type. Instead, these findings support a sampling approach that derives photosynthetic fluxes from a consideration of both canopy light absorption (e.g., normalized difference vegetation index) and photosynthetic light‐use efficiency (e.g., photochemical reflectance index). Such sampling should improve our understanding of controls on photosynthetic carbon uptake in diverse tropical forest stands.
Regional‐Scale Variation in Litter Production and Seasonality in Tropical Dry Forests of Southern Mexico1
Authors: Lawrence Deborah 
Published: November 2005

ABSTRACTHighly seasonal rainfall creates a pulse of litterfall in the southern Yucatan peninsula region, with cascading effects on the timing of essential nutrient fluxes, microbial dynamics, and vegetation growth. I investigated whether forest age or a regional environmental gradient related to rainfall has a greater effect on patterns of litterfall in this increasingly human‐dominated landscape. Litterfall was sampled in 10–13 stands in each of three locations spanning a rainfall gradient of ca 900–1400 mm/yr. Litter was collected monthly from November 1998 through January 2000 in mature forests and in secondary forests aged 2–25 yr. Despite a substantial precipitation gradient, age was the only significant predictor of annual litter mass. Two‐ to five‐yr‐old forests produced significantly less litter than 12–25‐yr‐old secondary forests (4.6 vs. 6.2 Mg/ha/yr), but the difference between older secondary forests and mature forests (9 percent) was not significant. Litter production increased with rainfall, but not significantly so. The pattern of litterfall was similar across locations and age classes, with a peak during late March or early April. However, litterfall seasonality was most pronounced in the old secondary and mature forests. Litterfall was more evenly distributed throughout the year in forests under 10 yr old. Seasonality of litterfall was also less pronounced at the wettest site, with less disparity between peak litterfall and off‐peak months. Seasonality was not related to soil texture. Forest age and rainfall are important drivers of litterfall dynamics; however, both litter mass and degree of seasonality depended more strongly on forest age. Thus, the impact of land‐use change on litter nutrient cycling is as great, if not greater, than the constraint imposed by the major natural environmental factor affecting tropical dry forests.
The Influence of Hurricane Winds on Caribbean Dry Forest Structure and Nutrient Pools1
Authors: Van Bloem Skip J. , Murphy Peter G. , Lugo Ariel E. , Ostertag Rebecca , Costa María Rivera , Bernard Ivelisse Ruiz , Colón Sandra Molina , Mora Miguel Canals 
Published: November 2005

ABSTRACTIn 1998, we measured the effects of Hurricane Georges after it passed over long‐term research sites in Puerto Rican dry forest. Our primary objectives were to quantify hurricane effects on forest structure, to compare effects in a large tract of forest versus a series of nearby forest fragments, to evaluate short‐term response to hurricane disturbance in terms of mortality and sprouting, and to assess the ability of hurricanes to maintain forest structure. We sampled damage from 33 plots (1.3 ha) across a 3000‐ha tract of forest as well as in 19 fragments. For stems with 2.5‐cm minimum diameter, 1004 stems/ha (12.4%) suffered structural damage, while 69 percent of the undamaged stems were at least 50 percent defoliated. Basal area lost to structural damage equaled 4.0 m2/ha (22%) in south‐facing native forests. Structural damage and defoliation increased with stem diameter and were more common in certain dry forest species. South‐facing forests and those on ridgetops incurred more damage than north‐facing forests or those comprised primarily of introduced species. Stem mortality was only 2 percent of all stems after 9 mo. Structural damage did not necessarily result in stem mortality. Hurricane‐induced mortality was not associated with stem height or diameter, but was ten times greater than background mortality. Basal sprouting was proportional to the amount of structural damage incurred in a stand. Forest fragments experienced the same patterns of hurricane effects as the reference forest. The low, dense structure of Caribbean dry forest can be maintained by hurricane damage to larger stems and induction of basal sprouting to generate multistemmed trees.
Seasonal Patterns of Flowering and Fruiting in a Dry Tropical Forest in Jamaica1
Authors: McLaren Kurt P. , McDonald Morag A. 
Published: November 2005

ABSTRACTTropical dry forests occupy more area and are more endangered than rainforests, yet their regeneration ecology has received less study and is consequently poorly understood. We recorded the flowering and fruiting phenology of a tropical dry forest in Jamaica over a period of 26 mo within ten 15 × 15‐m plots. Community‐wide recruitment reached a maximum in the wet season, whereas no recruitment occurred during the dry season. We observed a unimodal peak in rainfall and fruit production, and the periodicity and intensity of seed production were significantly correlated with rainfall seasonality (the optimal time for germination). Flowering at the community and system levels lagged behind a significant increase and subsequent decrease in rainfall by 7 and 3 mo, respectively, indicating that the dominant factor controlling flowering periodicity is the passage of the major (4‐mo long) rainy season and changes in soil moisture conditions. Fruiting lagged behind flowering by 2 mo and a significant increase in fruiting occurred 2 mo prior to a significant increase in rainfall. At the population level, a correspondence analysis identified a major dichotomy in the patterns of flowering and fruiting between species and indicated two broad species groups based on their time of peak fruiting and the number of times they were in fruit. These were either individuals which were usually in peak fruit 1–2 mo prior to the start of the major rainy season or those that were in fruit more or less continuously throughout the year with no peak fruiting time. This study supports the view that seasonal variation in rainfall and hence soil water availability constitutes both the proximate and the ultimate cause of flowering periodicity in tropical dry forests.
Phyllostomid Bat Community Structure and Abundance in Two Contrasting Tropical Dry Forests1
Authors: Stoner Kathryn E. 
Published: November 2005

ABSTRACTAlthough tropical wet forests are generally more diverse than dry forests for many faunal groups, few studies have compared bat diversity among dry forests. I compared ground level phyllostomid bat community structure between two tropical dry forests with different precipitation regimes. Parque National Palo Verde in northwestern Costa Rica represents one of the wettest tropical dry forests (rainfall 1.5 m/yr), whereas the Chamela‐Cuixmala Biosphere Reserve on the Pacific coast of central Mexico represents one of the driest (750 mm/yr). Mist net sampling was conducted at the two study sites to compare changes in ground level phyllostomid bat community structure between regions and seasons. Palo Verde was more diverse than Chamela and phyllostomid species showed low similarity between sites (Classic Jaccard = 0.263). The distinct phyllostomid communities observed at these two dry forest sites demonstrates that variants of tropical dry forest can be sufficiently different in structure and composition to affect phyllostomid communities. At both dry forest sites, abundance of the two most common foraging guilds (frugivores and nectarivores) differed between seasons, with greatest numbers of individuals captured coinciding with highest chiropterophilic resource abundance.