State of the field: Latin American decolonial philosophies of science.

Today, new histories of science are producing skeptical questions about the supposedly international philosophies of science that prevail in the North. The conceptual resources of such philosophies seem inadequate to enable them to interact effectively with how sciences and their philosophies do, could, and should function in today's economic, political, social and cultural, local and global contexts. How international, or universal, are these philosophies of science in reality? Here the focus will be on just one strain of these challenges. This one has emerged from Latin Americans who are creating anti-colonial histories and philosophies of knowledge production. They have named it modernity/coloniality/decolonial theory (MCD). They intend to develop a philosophy of science adequate for its own, Latin American needs. In the process, they transform typical Northern assumptions about modernity, its origins and its effects on Northern philosophies of science, as these are understood in both Latin America and around the globe. Five aspects of the MCD accounts will be discussed here. The first is historical differences between the worlds of the Spanish and Portuguese colonization of the Americas in the sixteenth century and of the worlds of the mostly British colonization of India and Africa in the 'long nineteenth century'. Second is feminist and anti-racist issues in these Latin American histories. Third is the neglect of these histories in the North. Fourth is the continuing effects of the rise and fall of a positivist philosophy of science in Latin America. The fifth is two progressive post-positivist tensions for Northern philosophy of science produced in this work.

The delivery of specialist spinal cord injury services in Queensland and the potential for telehealth.

BACKGROUND: The Queensland Spinal Cord Injuries Service (QSCIS) is a statewide service in Brisbane at the Princess Alexandra Hospital (PAH). The QSCIS assists individuals with a spinal cord injury (SCI) through three services: the Spinal Injuries Unit (SIU), Transitional Rehabilitation Program (TRP) and the Spinal Outreach Team (SPOT). The aim of this study was to undertake a review of ambulatory services provided by the QSCIS (SIU and SPOT) to help identify where telehealth may potentially be useful. METHODS: Profiling of patients with SCI in Queensland was achieved using database records containing referral data. Services provided by SIU Outpatient Clinics and the SPOT during a 6-year period (January 2008 - December 2013), were analysed. Using postcodes, we estimated distances between place of residence and Brisbane. We compared the general population of SCI patients with patients managed through SIU Outpatient Clinics and the SPOT. RESULTS: During the 6-year period, 2073 patients were referred to the QSCIS (and living) at the time of the analysis. 74% of all patients were male. The median age was 51y (IQR 39y-61y). About two-thirds of all patients lived within 200 km of Brisbane. 24% of all patients registered with the QSCIS lived further than 200 km away from Brisbane. 7513 appointments were provided in the SIU outpatient clinic. 43,827 occasions of service were reported by the SPOT, including telephone consultations (66%) and home visits (26%). 72 outreach clinics were held in selected regional sites for up to 100 patients per year. 13 videoconference appointments reported. 90% of all patients who attended the SIU outpatient clinic lived within 200 km of Brisbane. About two-thirds of patients who received a service from the SPOT lived within 200 km of Brisbane. CONCLUSION: Since one third of all patients registered with the QSCIS live at least 200 km away from Brisbane; it appears that these patients may not be accessing the same services as Brisbane based patients. Telehealth models of care, which promote better engagement with local health service providers (such as general practitioners, nurse practitioners and allied health professionals) could improve equity of access and reduce the need for extensive travel.

A dual-tracer study of extrastriatal 6-[18F]fluoro-m-tyrosine and 6-[18F]-fluoro-L-dopa uptake in Parkinson's disease.

6-[(18)F]-Fluoro-L-dopa (FDOPA) has been widely used as a biomarker for catecholamine synthesis, storage, and metabolism--its intense uptake in the striatum, and fainter uptake in other brain regions, is correlated with the symptoms and pathophysiology of Parkinson's disease (PD). 6-[(18)F]fluoro-m-tyrosine (FMT), which also targets L-amino acid decarboxylase, has potential advantages over FDOPA as a radiotracer because it does not form catechol-O-methyltransferase (COMT) metabolites. The purpose of the present study was to compare the regional distribution of these radiotracers in the brains of PD patients. Fifteen Parkinson's patients were studied with FMT and FDOPA positron emission tomography (PET) as well as high-resolution structural magnetic resonance imaging (MRI). MRI's were automatically parcellated into neuroanatomical regions of interest (ROIs) in Freesurfer (http://surfer.nmr.mgh.harvard.edu); region-specific uptake rate constants (Kocc) were generated from coregistered PET using a Patlak graphical approach. The essential findings were as follows: (1) regional Kocc were highly correlated between the radiotracers and in agreement with a previous FDOPA studies that used different ROI selection techniques; (2) FMT Kocc were higher in extrastriatal regions of relatively large uptake such as amygdala, pallidum, brainstem, hippocampus, entorhinal cortex, and thalamus, whereas cortical Kocc were similar between radiotracers; (3) while subcortical uptake of both radiotracers was related to disease duration and severity, cortical uptake was not. These results suggest that FMT may have advantages for examining pathologic changes within allocortical loop structures, which may contribute to cognitive and emotional symptoms of PD.

White matter microstructural integrity and executive function in Parkinson's disease.

Recent studies suggest that white matter abnormalities contribute to both motor and non-motor symptoms of Parkinson's disease. The present study was designed to investigate the degree to which diffusion tensor magnetic resonance imaging (DTI) indices are related to executive function in Parkinson's patients. We used tract-based spatial statistics to compare DTI data from 15 patients to 15 healthy, age- and education-matched controls. We then extracted mean values of fractional anisotropy (FA) and mean diffusivity (MD) within an a priori frontal mask. Executive function composite Z scores were regressed against these DTI indices, age, and total intracranial volume. In Parkinson's patients, FA was related to executive composite scores, and both indices were related to Stroop interference scores. We conclude that white matter microstructural abnormalities contribute to cognitive deficits in Parkinson's disease. Further work is needed to determine whether these white matter changes reflect the pathological process or a clinically important comorbidity.

Gut inflammation associated with age and Alzheimer's disease pathology: a human cohort study.

Age-related disease may be mediated by low levels of chronic inflammation ("inflammaging"). Recent work suggests that gut microbes can contribute to inflammation via degradation of the intestinal barrier. While aging and age-related diseases including Alzheimer's disease (AD) are linked to altered microbiome composition and higher levels of gut microbial components in systemic circulation, the role of intestinal inflammation remains unclear. To investigate whether greater gut inflammation is associated with advanced age and AD pathology, we assessed fecal samples from older adults to measure calprotectin, an established marker of intestinal inflammation which is elevated in diseases of gut barrier integrity. Multiple regression with maximum likelihood estimation and Satorra-Bentler corrections were used to test relationships between fecal calprotectin and clinical diagnosis, participant age, cerebrospinal fluid biomarkers of AD pathology, amyloid burden measured using 11C-Pittsburgh compound B positron emission tomography (PiB PET) imaging, and performance on cognitive tests measuring executive function and verbal learning and recall. Calprotectin levels were elevated in advanced age and were higher in participants diagnosed with amyloid-confirmed AD dementia. Additionally, among individuals with AD dementia, higher calprotectin was associated with greater amyloid burden as measured with PiB PET. Exploratory analyses indicated that calprotectin levels were also associated with cerebrospinal fluid markers of AD, and with lower verbal memory function even among cognitively unimpaired participants. Taken together, these findings suggest that intestinal inflammation is linked with brain pathology even in the earliest disease stages. Moreover, intestinal inflammation may exacerbate the progression toward AD.

A within-subject comparison of 6-[18F]fluoro-m-tyrosine and 6-[18F]fluoro-L-dopa in Parkinson's disease.

Progression of Parkinson's disease symptoms is imperfectly correlated with positron emission tomography biomarkers for dopamine biosynthetic pathways. The radiopharmaceutical 6-[(18) F]fluoro-m-tyrosine is not a substrate for catechol-O-methyltransferase and therefore has a more favorable uptake-to-background ratio than 6-[(18) F]fluoro-L-dopa. The objective of this study was to evaluate 6-[(18) F]fluoro-m-tyrosine relative to 6-[(18) F]fluoro-L-dopa with partial catechol-O-methyltransferase inhibition as a biomarker for clinical status in Parkinson's disease. Twelve patients with early-stage Parkinson's disease, off medication, underwent Unified Parkinson Disease Rating Scale scoring, brain magnetic resonance imaging, and 3-dimensional dynamic positron emission tomography using equivalent doses of 6-[(18) F]fluoro-m-tyrosine and 6-[(18) F]fluoro-L-dopa with tolcapone, a catechol-O-methyltransferase inhibitor. Images were realigned within subject, after which the tissue-derived uptake rate constant was generated for volumes of interest encompassing the caudate nucleus, putamen, and subregions of the putamen. We computed both bivariate (Pearson) and partial (covariate of age) correlations between clinical subscores and tissue-derived uptake rate constant. Tissue-derived uptake rate constant values were correlated between the radiopharmaceuticals (r = 0.8). Motor subscores were inversely correlated with the contralateral putamen 6-[(18) F]fluoro-m-tyrosine tissue-derived uptake rate constant (|r| > 0.72, P < .005) but not significantly with the 6-[(18) F]fluoro-L-dopa tissue-derived uptake rate constant. The uptake rate constants for both radiopharmaceuticals were also inversely correlated with activities of daily living subscores, but the magnitude of correlation coefficients was greater for 6-[(18) F]fluoro-m-tyrosine. In this design, 6-[(18) F]fluoro-m-tyrosine uptake better reflected clinical status than did 6-[(18) F]fluoro-L-dopa uptake. We attribute this finding to 6-[(18) F]fluoro-m-tyrosine's higher affinity for the target, L-aromatic amino acid decarboxylase, and the absence of other major determinants of the uptake rate constant. These results also imply that L-aromatic amino acid decarboxylase activity is a major determinant of clinical status.

Gut microbiome alterations in Alzheimer's disease.

Alzheimer's disease (AD) is the most common form of dementia. However, the etiopathogenesis of this devastating disease is not fully understood. Recent studies in rodents suggest that alterations in the gut microbiome may contribute to amyloid deposition, yet the microbial communities associated with AD have not been characterized in humans. Towards this end, we characterized the bacterial taxonomic composition of fecal samples from participants with and without a diagnosis of dementia due to AD. Our analyses revealed that the gut microbiome of AD participants has decreased microbial diversity and is compositionally distinct from control age- and sex-matched individuals. We identified phylum- through genus-wide differences in bacterial abundance including decreased Firmicutes, increased Bacteroidetes, and decreased Bifidobacterium in the microbiome of AD participants. Furthermore, we observed correlations between levels of differentially abundant genera and cerebrospinal fluid (CSF) biomarkers of AD. These findings add AD to the growing list of diseases associated with gut microbial alterations, as well as suggest that gut bacterial communities may be a target for therapeutic intervention.

Anterior cingulate dopamine turnover and behavior change in Parkinson's disease.

Subtle cognitive and behavioral changes are common in early Parkinson's disease. The cause of these symptoms is probably multifactorial but may in part be related to extra-striatal dopamine levels. 6-[(18) F]-Fluoro-L-dopa (FDOPA) positron emission tomography has been widely used to quantify dopamine metabolism in the brain; the most frequently measured kinetic parameter is the tissue uptake rate constant, Ki. However, estimates of dopamine turnover, which also account for the small rate of FDOPA loss from areas of specific trapping, may be more sensitive than Ki for early disease-related changes in dopamine biosynthesis. The purpose of the present study was to compare effective distribution volume ratio (eDVR), a metric for dopamine turnover, to cognitive and behavioral measures in Parkinson's patients. We chose to focus the investigation on anterior cingulate cortex, which shows highest FDOPA uptake within frontal regions and has known roles in executive function. Fifteen non-demented early-stage PD patients were pretreated with carbidopa and tolcapone, a central catechol-O-methyl transferase (COMT) inhibitor, and then underwent extended imaging with FDOPA PET. Anterior cingulate eDVR was compared with composite scores for language, memory, and executive function measured by neuropsychological testing, and behavior change measured using two informant-based questionnaires, the Cambridge Behavioral Inventory and the Behavior Rating Inventory of Executive Function-Adult Version. Lower mean eDVR (thus higher dopamine turnover) in anterior cingulate cortex was related to lower (more impaired) behavior scores. We conclude that subtle changes in anterior cingulate dopamine metabolism may contribute to dysexecutive behaviors in Parkinson's disease.

Active palliative anti-cancer therapy.

Palliative care has a high profile in the delivery of cancer care services and is of growing interest to all health care practitioners. This reflects a marked change in attitudes to the management of cancer: not too long ago, nurses were forbidden to discuss treatment with patients, who were often ignorant of their diagnosis. Now, the focus has shifted to optimising quality of life in a comprehensive package of total care involving the patient and the family.

Amyloid burden and neural function in people at risk for Alzheimer's Disease.

To determine the relationship between amyloid burden and neural function in healthy adults at risk for Alzheimer's Disease (AD), we used multimodal imaging with [C-11]Pittsburgh compound B positron emission tomography, [F-18]fluorodeoxyglucose, positron emission tomography , and magnetic resonance imaging, together with cognitive measurement in 201 subjects (mean age, 60.1 years; range, 46-73 years) from the Wisconsin Registry for Alzheimer's Prevention. Using a qualitative rating, 18% of the samples were strongly positive Beta-amyloid (Aß+), 41% indeterminate (Aßi), and 41% negative (Aß-). Aß+ was associated with older age, female sex, and showed trends for maternal family history of AD and APOE4. Relative to the Aß- group, Aß+ and Aßi participants had increased glucose metabolism in the bilateral thalamus; Aß+ participants also had increased metabolism in the bilateral superior temporal gyrus. Aß+ participants exhibited increased gray matter in the lateral parietal lobe bilaterally relative to the Aß- group, and no areas of significant atrophy. Cognitive performance and self report cognitive and affective symptoms did not differ between groups. Amyloid burden can be identified in adults at a mean age of 60 years and is accompanied by glucometabolic increases in specific areas, but not atrophy or cognitive loss. This asymptomatic stage may be an opportune window for intervention to prevent progression to symptomatic AD.

An Argonaute transports siRNAs from the cytoplasm to the nucleus.

Ribonucleoprotein complexes consisting of Argonaute-like proteins and small regulatory RNAs function in a wide range of biological processes. Many of these small regulatory RNAs are predicted to act, at least in part, within the nucleus. We conducted a genetic screen to identify factors essential for RNA interference (RNAi) in nuclei of Caenorhabditis elegans and identified the Argonaute protein NRDE-3. In the absence of small interfering RNAs (siRNAs), NRDE-3 resides in the cytoplasm. NRDE-3 binds siRNAs generated by RNA-dependent RNA polymerases acting on messenger RNA templates in the cytoplasm and redistributes to the nucleus. Nuclear redistribution of NRDE-3 requires a functional nuclear localization signal, is required for nuclear RNAi, and results in NRDE-3 association with nuclear-localized nascent transcripts. Thus, specific Argonaute proteins can transport specific classes of small regulatory RNAs to distinct cellular compartments to regulate gene expression.

Functional proteomics reveals the biochemical niche of C. elegans DCR-1 in multiple small-RNA-mediated pathways.

In plants, animals, and fungi, members of the Dicer family of RNase III-related enzymes process double-stranded RNA (dsRNA) to initiate small-RNA-mediated gene-silencing mechanisms. To learn how C. elegans Dicer, DCR-1, functions in multiple distinct silencing mechanisms, we used a mass-spectrometry-based proteomics approach to identify DCR-1-interacting proteins. We then generated and characterized deletion alleles for the corresponding genes. The interactors are required for production of three species of small RNA, including (1) small interfering RNAs (siRNAs), derived from exogenous dsRNA triggers (exo-siRNAs); (2) siRNAs derived from endogenous triggers (endo-siRNAs); and (3) developmental regulatory microRNAs (miRNAs). One interactor, the conserved RNA-phosphatase homolog PIR-1, is required for the processing of a putative amplified DCR-1 substrate. Interactors required for endo-siRNA production include ERI-1 and RRF-3, whose loss of function enhances RNAi. Our findings provide a first glimpse at the complex biochemical niche of Dicer and suggest that competition exists between DCR-1-mediated small-RNA pathways.