Long-term decline of the Amazon carbon sink

Atmospheric carbon dioxide records indicate that the land surface has acted as a strong global carbon sink over recent decades, with a substantial fraction of this sink probably located in the tropics, particularly in the Amazon. Nevertheless, it is unclear how the terrestrial carbon sink will evolve as climate and atmospheric composition continue to change. Here we analyse the historical evolution of the biomass dynamics of the Amazon rainforest over three decades using a distributed network of 321 plots. While this analysis confirms that Amazon forests have acted as a long-term net biomass sink, we find a long-term decreasing trend of carbon accumulation. Rates of net increase in above-ground biomass declined by one-third during the past decade compared to the 1990s. This is a consequence of growth rate increases levelling off recently, while biomass mortality persistently increased throughout, leading to a shortening of carbon residence times. Potential drivers for the mortality increase include greater climate variability, and feedbacks of faster growth on mortality, resulting in shortened tree longevity. The observed decline of the Amazon sink diverges markedly from the recent increase in terrestrial carbon uptake at the global scale, and is contrary to expectations based on models.

Managing knee ostheoarthritis: efficacy of hyaluronic acid injections

Osteoarthritis (OA) is the most common form of chronic arthritis worldwide. The etiology of pain in osteoarthritis is multifactoral, and includes mechanical and inflammatory processes. The use of intra-articular viscosupplementation in the nonoperative management of patients with osteoarthritis has become quite popular. Recent clinical data have demonstrated that the anti-inflammatory and chondroprotective actions of hyaluronic acid viscosupplementation reduce pain, from 4 to 14 weeks after injection, while improving patient function. Viscosupplements are comparable in efficacy to systemic forms of active intervention, with more local reactions but fewer systemic adverse events, and hyaluronic acid has more prolonged effects than IA corticosteroids. Although several randomized controlled trials have established the efficacy of this treatment modality, additional high quality randomized control studies with appropriate comparison are still required to clearly define the role of intra-articular hyaluronic acid injections in the treatment of osteoarthritis. We review the basic science and development of viscosupplementation and discuss the mounting evidence in support of its efficacy and safety profile.

Trauma, stressful life events and depression predict HIV-related fatigue

Despite the fact that fatigue is a common and debilitating symptom among HIV-infected persons, we know little about the predictors of fatigue in this population. The goal of this cross-sectional study was to examine the effects of early childhood trauma, recent stressful life events and depression on intensity and impairment of fatigue in HIV, over and above demographic factors and clinical characteristics. We studied 128 HIV-infected men and women from one southern state. The median number of childhood traumatic events was two and participants tended to have at least one moderate recent stressful event. Multiple regression findings showed that patients with less income, more childhood trauma, more recent stressful events and more depressive symptoms had greater fatigue intensity and fatigue-related impairment in daily functioning. Recent stresses were a more powerful predictor of fatigue than childhood trauma. None of the disease-related measures (e.g. CD4, viral load, antiretroviral medication) predicted fatigue. Although stress and trauma have been related to fatigue in other populations, this is the first study to examine the effects of traumatic and recent stressful life events on fatigue in an HIV-infected sample.

Measuring fatigue in people living with HIV/AIDS: psychometric characteristics of the HIV-related fatigue scale

In the era of life-prolonging antiretroviral therapy, chronic fatigue is one of the most prevalent and disabling symptoms of people living with HIV/AIDS, yet its measurement remains challenging. No instruments have been developed specifically to describe HIV-related fatigue. We assessed the reliability and construct validity of the HIV-Related Fatigue Scale (HRFS), a 56-item self-report instrument developed through formative qualitative research and designed to measure the intensity and consequences of fatigue as well as the circumstances surrounding fatigue in people living with HIV. The HRFS has three main scales, which measure fatigue intensity, the responsiveness of fatigue to circumstances and fatigue-related impairment of functioning. The functioning scale can be further divided into subscales measuring impairment of activities of daily living, impairment of mental functioning and impairment of social functioning. Each scale demonstrated high internal consistency (Cronbach's alpha=0.93, 0.91 and 0.97 for the intensity, responsiveness and functioning scales, respectively). The HRFS scales also demonstrated satisfactory convergent validity when compared to other fatigue measures. HIV-Related Fatigue Scales were moderately correlated with quality of nighttime sleep (rho=0.46, 0.47 and 0.35) but showed only weak correlations with daytime sleepiness (rho=0.20, 0.33 and 0.18). The scales were also moderately correlated with general mental and physical health as measured by the SF-36 Health Survey (rho ranged from 0.30 to 0.68 across the 8 SF-36 subscales with most >0.40). The HRFS is a promising tool to help facilitate research on the prevalence, etiology and consequences of fatigue in people living with HIV.

[Verbal fluency in school-aged Spanish children: normative data and analysis of clustering and switching strategies]

INTRODUCTION

Verbal fluency tasks are highly sensitive to the presence of brain pathology. The use of verbal fluency tasks in paediatric clinical neuropsychology requires knowing how the execution progresses across age. Developmental changes in children's verbal fluency were explored in this study.

SUBJECTS AND METHODS

Participants were 79 school-aged children divided into three age groups. Phonemic (FAM) and semantic (animals) fluency task were administered. Three scores were obtained for qualitative analyses: number of clusters, switches and mean cluster size.

RESULTS

Children in older groups generated more words in phonemic fluency than children in 6-7 years group. In semantic fluency differences were significant only between the 10-11 years group and the youngest group. In both tasks year-group effects were found in number of clusters and number of switches. High positive correlations were found between total production and number of cluster and number of switches.

CONCLUSIONS

Results suggest that the development of the capability to generate words is related to the maturation of frontal component of the task. That means, that it is related to development of a greater cognitive flexibility that allows more efficient strategic search processes. Data obtained, although preliminary, may be useful to evaluate the executive functions in Spanish speaking paediatric population.

Progression to AIDS, a clinical AIDS condition and mortality: psychosocial and physiological predictors

BACKGROUND

The primary aim of this study is to examine prospectively the association of stressful life events, social support, depressive symptoms, anger, serum cortisol and lymphocyte subsets with changes in multiple measures of human immunodeficiency virus (HIV) disease progression.

METHODS

Ninety-six HIV-infected gay men without symptoms or anti-retroviral medication use at baseline were studied every 6 months for up to 9 years. Disease progression was defined in three ways using the Centers for Disease Control (CDC) classifications (e.g. AIDS, clinical AIDS condition and mortality). Cox regression models with time-dependent covariates were used, adjusting for control variables (e.g. race, age, baseline, CD4 T cells and viral load, number of anti-retroviral medications).

RESULTS

Higher cumulative average stressful life events and lower cumulative average social support predicted faster progression to both the CDC AIDS classification and a clinical AIDS condition. Higher anger scores and CD8 T cells were associated with faster progression to AIDS, and depressive symptoms were associated with faster development of an AIDS clinical condition. Higher levels of serum cortisol predicted all three measures of disease progression.

CONCLUSIONS

These results suggest that stressful life events, dysphoric mood and limited social support are associated with more rapid clinical progression in HIV infection, with serum cortisol also exerting an independent effect on disease progression.

Production and characteristics of Debaryomyces hansenii killer toxin

The optimal conditions for the production of the killer toxin of Debaryomyces hansenii CYC 1021 have been studied. The lethal activity of the killer toxin increased with the presence of NaCl in the medium used for testing the killing action. Production of the killer toxin was stimulated in the presence of proteins of complex culture media. Addition of nonionic detergents and other additives, such as dimethylsulfoxide enhanced killer toxin production significantly. Killer toxin secretion pattern followed the growth curve and reached its maximum activity at the early stationary phase. Optimal stability was observed at pH 4.5 and temperatures up to 20 degrees C. Above pH 4.5 a steep decrease of the stability was noted. The activity was hardly detectable at pH 5.1.

(1-->6)-Beta-D-glucan as the cell wall binding site for Debaryomyces hansenii killer toxin

AIMS

The aims of this study were to characterize the cell wall binding site of Debaryomyces hansenii killer toxin to provide a simple purification method and to determine some characteristics of this toxin.

METHODS AND RESULTS

Various linear (1-->6)-beta-D-glucans of different origins were effective competitive inhibitors of the toxin action. Periodate oxidation and 1H-NMR was used to determine the receptor nature. Affinity chromatography on pustulan-Sepharose column was used to purify D. hansenii killer toxin, probably a 23-kDa protein. The killer toxin character was cureless.

CONCLUSIONS

The investigation revealed that the killer toxin was mainly adsorbed by (1-->6)-beta-D-glucans. This is a low molecular weight protein, probably encoded by chromosomal genes.

SIGNIFICANCE AND IMPACT OF THE STUDY

The specificity of the killer toxin for its receptor provides an effective means to purify the killer toxin. This study is the first to identify the cell wall binding site of this killer toxin, a toxin with properties of industrial relevance.

In the field with the Beck depression inventory

Qualitative methods are typically and formally used only in the earliest phases of instrument development to generate items. Once these items are generated, instrument development usually then moves into the testing phases, where quantitative methods prevail. The achievement of psychometric credibility is presumed to depend largely on quantitative measures of reliability and validity. Or if qualitative methods are employed, their use is masked, unfocused, and/or unplanned. The planned use of qualitative methods is critical in every phase of instrument use and in all studies that depend for their results on instruments, and their use is critical in illuminating problems with existing instruments. The authors illustrate these points by drawing on the first author's experiences in the field with the Beck Depression Inventory in her research program on managing fatigue in persons with HIV/AIDS.

[Study of brain asymmetry with neurologically normal subjects: visual procedures]

OBJECTIVES

We present a revision of the technique of visual lateralization of stimuli as one approach to the study of brain asymmetry with regard to language. At the same time, we present a summary of the research carried out by our group using these techniques, reflecting not only the main results but also the most relevant methodological aspects.

DEVELOPMENT

Brain asymmetry is a basic characteristic of the organization of the nervous system. In most of the principal psychological processes there exists a greater or lesser degree of hemispheric differentiation. Among these, language is possibly one of the processes most noticeably lateralized. One of the main approaches in this field is the study of neurologically normal subjects using techniques of visual lateralization of stimuli. Appropriate use of this technique requires a knowledge of the basic principles involved and of the methodological requirement, as well as the different types of tasks and stimuli, which can be adapted to these requirements.

CONCLUSIONS

The technique of lateralization of visual stimuli has a long tradition as a procedure for the study of cerebral asymmetry for language and is within the possibilities of most laboratories. However, ensuring correct lateralization requires rigorous controls and this has to be taken into consideration in the selection and adaptation of the experimental paradigm to be used. Several of these paradigms are used in our research and our results provide evidence of the relative character of cerebral asymmetry and of the participation of the right hemisphere in lexico-semantic processing.

Comparison between African-American and white women in their beliefs about breast cancer and their health locus of control

The purpose of this study was to examine the health beliefs of African-American and white women about breast cancer and locus of control, using the health belief model and the health locus of control construct. The Health Screening Questionnaire, developed by Sugarek, Deyo, and Holmes, was used to collect self-report data about health beliefs related to breast cancer and health locus of control. Participants included 197 white and 152 African-American women, between the ages of 19 and 93, recruited from various settings in central Florida. Significant differences were found between the two groups on all of the health beliefs about cancer items. The African-American women were significantly more likely to believe in chance, or to depend on powerful others for their health. Perceived susceptibility to cancer, doubts about the value of early diagnosis, and beliefs about the seriousness of breast cancer all were significantly associated with powerful other scores among African-American women. There was no relation between health beliefs and years of education for African-American women, but for white women, those with the least education were more likely to believe that death was inevitable with a cancer diagnosis. These results add to the information needed for the development of effective programs aimed at increasing breast cancer screening among African-American women.

[Neuropsychological assessment in multiple sclerosis]

OBJECTIVE

Over the past 20 years great advances have been made in understanding the neuropsychological changes in multiple sclerosis. In this paper we review the nature of mental deterioration in multiple sclerosis and the procedures used for its evaluation.

DEVELOPMENT

First we give a short summary of present knowledge of the involvement of different functions and the instruments most generally used to evaluate it. We then consider the different approaches to neuropsychological assessment, the use of broad guidelines as opposed to screening techniques, bearing in mind their advantages and disadvantages in the clinical field and in investigation. Similarly we mention the current trends in the evaluation and treatment of multiple sclerosis.

CONCLUSIONS

The general profile of neuropsychological alterations in multiple sclerosis is characterized by the presence of changes in secondary memory and speed of thought, although the nature of this defect is still not clear. Changes are also seen in other neuropsychological functions, although less frequently and more controversially. Our knowledge of the prevalence of these changes comes from the use of guidelines for thorough examination. However, the current tendency is to seek instruments for evaluation which combine diagnostic efficiency, clinical usefulness and brevity. In this respect, although progress is being made, there are still questions to be answered.

Metasynthesis of qualitative research on living with HIV infection

Qualitative studies of people living with HIV infection are crucial for providing direction for practice and research because they provide the emic perspective. As more of these qualitative studies are conducted, researchers are challenged to develop ways to synthesize the findings for research and clinical practice. The purpose of the metasynthesis described in this article was to understand the experience of adults living with HIV infection as described in published research. Findings from the studies were categorized into six overarching metaphors: (a) finding meaning in HIV/AIDS, (b) shattered meaning, (c) human connectedness, (d) focusing on the self, (e) negotiating health care, and (f) dealing with stigma.

Hemispheric asymmetry in lexical decisions: the effects of grammatical class and imageability

It has been suggested that neural systems for lexical processing of nouns and verbs are anatomically distinct. The aim of the present study was to investigate if brain asymmetry for the processing of these two grammatical classes is also different. Neurologically intact adults performed a lateralized lexical decision task with grammatically unambiguous words of high, medium, and low degrees of imagery. For error scores a right visual field (RVF) advantage and an overall effect of imageability were obtained. For latency scores grammatical class and imageability modified visual field differences: in the noun class a RVF advantage was obtained only for low imagery nouns, while for the verbs the RVF advantage was present for both medium and low imagery verbs. These results suggest that the participation of right hemisphere neural systems in the processing of verbs is more limited than in the processing of nouns.

A review of fatigue in people with HIV infection

Fatigue is often cited by clinicians as a debilitating symptom suffered by the many who are infected with HIV. This article provides a review of HIV-related fatigue, including research on possible physiological causes such as anemia, CD4 count, impaired liver function, impaired thyroid function, and cortisol abnormalities. Psychological causes of fatigue, particularly depression, are reviewed as well. Measurement issues, such as the use of inappropriate tools, the problem of measuring the presence or absence of fatigue, and the use of tools developed for other groups of patients, are reviewed. The need for a comprehensive fatigue tool that is appropriate for people with HIV is discussed. Current treatment research, including thyroid replacement, hyperbaric oxygen, and dextroamphetamine, is presented. Finally, the implications for further research, including the need for qualitative studies to learn more about the phenomenon, develop an instrument to measure fatigue, and examine variables together to get a complete picture of this complex concept, are reviewed.

Long-term nonprogressors with HIV disease

BACKGROUND

Although biomedical research is being conducted on long-term nonprogressors with HIV disease, there is relatively little research on the psychosocial factors influencing this phenomenon.

OBJECTIVE

To describe the perceptions of long-term nonprogressors of their HIV disease and its course.

METHOD

A naturalistic study design was used to elicit information from 25 men and women who were long-term nonprogressors (HIV positive for 7 or more years, CD4 count > 500, and free of opportunistic infections and/or AIDS-defining illnesses). Audiotaped interviews were transcribed verbatim, and content analysis and constant comparison were used to elicit themes.

RESULTS

Themes include viewing HIV as a manageable illness, taking care of my physical health, human connectedness, taking care of my emotional/mental health, and spirituality. Specific ways of adapting to HIV are identified within each theme.

CONCLUSIONS

The results of this study can be used by nurses who work with HIV positive individuals in an effort to help them adopt strategies that may assist them in maintaining their health. However, longitudinal studies that follow this group over time and that include biomedical markers of disease progression would provide knowledge that would assist in the refinement of these interventions.