Mapping the impact of age and APOE risk factors for late onset Alzheimer's disease on long range brain connections through multiscale bundle analysis.

Alzheimer's disease currently has no cure and is usually detected too late for interventions to be effective. In this study we have focused on cognitively normal subjects to study the impact of risk factors on their long-range brain connections. To detect vulnerable connections, we devised a multiscale, hierarchical method for spatial clustering of the whole brain tractogram and examined the impact of age and APOE allelic variation on cognitive abilities and bundle properties including texture e.g., mean fractional anisotropy, variability, and geometric properties including streamline length, volume, and shape, as well as asymmetry. We found that the third level subdivision in the bundle hierarchy provided the most sensitive ability to detect age and genotype differences associated with risk factors. Our results indicate that frontal bundles were a major age predictor, while the occipital cortex and cerebellar connections were important risk predictors that were heavily genotype dependent, and showed accelerated decline in fractional anisotropy, shape similarity, and increased asymmetry. Cognitive metrics related to olfactory memory were mapped to bundles, providing possible early markers of neurodegeneration. In addition, physiological metrics such as diastolic blood pressure were associated with changes in white matter tracts. Our novel method for a data driven analysis of sensitive changes in tractography may differentiate populations at risk for AD and isolate specific vulnerable networks.

Clinician's perspectives on gene therapy for Alzheimer's disease: A qualitative study.

INTRODUCTION: We aimed to understand clinician views regarding gene therapy as a future treatment for Alzheimer's disease (AD) and potential barriers and facilitators to its use. METHODS: We interviewed ten clinicians who treat patients with AD. Clinicians helped design a semi-structured interview including the following domains: establishing understanding, cost/access, quality of life, and religion/spirituality. Transcripts were analyzed by a coding team using descriptive content analysis with inductive approach. RESULTS: Clinicians identified three main areas of concern: 1) potential clinician and patient understanding of gene therapy and Alzheimer's disease 2) consideration of inequity (i.e., care access, disease awareness along with education level, family support, trust in care systems); and 3) considerations in decision-making (i.e., religious/spiritual beliefs and method of treatment delivery as a decision-making tools). DISCUSSION AND CONCLUSION: Findings highlight areas for knowledge-building for patients and clinicians alike. Clinicians must be aware of patient/family educational needs and gaps in their own clinical knowledge before engaging patients/families with new technology. Allowing time for questions is crucial to building rapport and trust.

"Early in the morning, there's tolerance and later in the day it disappears" - The intersection of resource scarcity, stress and stigma in mental health and substance use care in South Africa.

Stress is a challenge among non-specialist health workers worldwide, particularly in low-resource settings. Understanding and targeting stress is critical for supporting non-specialists and their patients, as stress negatively affects patient care. Further, stigma toward mental health and substance use conditions also impacts patient care. However, there is little information on the intersection of these factors. This sub-analysis aims to explore how substance use and mental health stigma intersect with provider stress and resource constraints to influence the care of people with HIV/TB. We conducted semi-structured interviews (N=30) with patients (n=15) and providers (n=15, non-specialist health workers) within a low-resource community in Cape Town, South Africa. Data were analyzed using thematic analysis. Three key themes were identified: (1) resource constraints negatively affect patient care and contribute to non-specialist stress; (2) in the context of stress, non-specialists are hesitant to work with patients with mental health or substance use concerns, who they view as more demanding and (3) stress contributes to provider stigma, which negatively impacts patient care. Findings highlight the need for multilevel interventions targeting both provider stress and stigma toward people with mental health and substance use concerns, especially within the context of non-specialist-delivered mental health services in low-resource settings.

Piloting Siyakhana: A community health worker training to reduce substance use and depression stigma in South African HIV and TB care.

South Africa has one of the highest rates of HIV/tuberculosis (TB) co-infection, and poor engagement in HIV/TB care contributes to morbidity and mortality. In South Africa, community health workers (CHWs) are tasked with re-engaging patients who have dropped out of HIV/TB care. CHWs have described substantial challenges with substance use (SU) and depression among their patients, while patients have described CHW stigma towards SU and depression as barriers to re-engagement in care. Yet, CHWs receive little-to-no training on SU or depression. Therefore, we piloted Siyakhana, a brief CHW training to reduce stigma related to SU and depression while improving skills for re-engaging these patients in HIV and/or TB care. This study evaluated the preliminary effectiveness (stigma towards SU and depression; clinical competence assessed via roleplay) and implementation (quantitative ratings of feasibility, acceptability, appropriateness, adoption; semi-structured written qualitative feedback) of Siyakhana among CHWs and supervisors (N = 17) at pre- and post-training assessments. SU stigma significantly decreased (F(1,16) = 18.94, p < 0.001, ηp2 = 0.54). Depression stigma was lower than SU stigma at both timepoints and did not significantly decrease after training. CHW clinical competency towards patients with SU/depression significantly improved (t(11) = -3.35, p = 0.007, d = 1.00). The training was rated as feasible, acceptable, appropriate, and likely to be adopted by CHWs and their supervisors. Nonjudgmental communication was commonly described as the most useful training component. Based on this pilot, the training is being refined and evaluated in a larger randomized stepped-wedge clinical trial.

Neuropsychiatric Comorbidities and Psychotropic Medication Use in Medicare Beneficiaries With Dementia by Sex and Race.

BACKGROUND: Neuropsychiatric symptoms affect the majority of dementia patients. Past studies report high rates of potentially inappropriate prescribing of psychotropic medications in this population. We investigate differences in neuropsychiatric diagnoses and psychotropic medication prescribing in a local US cohort by sex and race. METHODS: We utilize Medicare claims and prescription fill records in a cohort of 100% Medicare North and South Carolina beneficiaries ages 50 and above for the year 2017 with a dementia diagnosis. We identify dementia and quantify diagnosis of anxiety, depression and psychosis using validated coding algorithms. We search Medicare claims for antianxiety, antidepressant and antipsychotic medications to determine prescriptions filled. RESULTS: Anxiety and depression were diagnosed at higher rates in White patients; psychosis at higher rates in Black patients. (P < .001) Females were diagnosed with anxiety, depression and psychosis at higher rates than males (P < .001) and filled more antianxiety and antidepressant medications than males. (P < .001) Black and Other race patients filled more antipsychotic medications for anxiety, depression and psychosis than White patients. (P < .001) Antidepressants were prescribed at higher rates than antianxiety or antipsychotic medications across all patients and diagnoses. Of patients with no neuropsychiatric diagnosis, 11.4% were prescribed an antianxiety medication, 22.8% prescribed an antidepressant and 7.6% prescribed an antipsychotic. CONCLUSIONS: The high fill rate of antianxiety (benzodiazepine) medications in dementia patients, especially females is a concern. Patients are prescribed psychotropic medications at high rates. This practice may represent potentially inappropriate prescribing. Patient/caregiver education with innovative community outreach and care delivery models may help decrease medication use.

Racial Disparities in Low-Value Care in the Last Year of Life for Medicare Beneficiaries With Neurodegenerative Disease.

Background and Objectives: There are racial disparities in health care services received by patients with neurodegenerative diseases, but little is known about disparities in the last year of life, specifically in high-value and low-value care utilization. This study evaluated racial disparities in the utilization of high-value and low-value care in the last year of life among Medicare beneficiaries with dementia or Parkinson disease. Methods: This was a retrospective, population-based cohort analysis using data from North and South Carolina fee-for-service Medicare claims between 2013 and 2017. We created a decedent cohort of beneficiaries aged 50 years or older at diagnosis with dementia or Parkinson disease. Specific low-value utilization outcomes were selected from the Choosing Wisely initiative, including cancer screening, peripheral artery stenting, and feeding tube placement in the last year of life. Low-value outcomes included hospitalization, emergency department visits, neuroimaging services, and number of days receiving skilled nursing. High-value outcomes included receipt of occupational and physical therapy, hospice care, and medications indicated for dementia and/or Parkinson disease. Results: Among 70,650 decedents, 13,753 were Black, 55,765 were White, 93.1% had dementia, and 7.7% had Parkinson disease. Adjusting for age, sex, Medicaid dual enrollment status, rural vs urban location, state (NC and SC), and comorbidities, Black decedents were more likely to receive low-value care including colorectal cancer screening (adjusted hazard ratio [aHR] 1.46 [1.32-1.61]), peripheral artery stenting (aHR 1.72 [1.43-2.08]), and feeding tube placement (aHR 2.96 [2.70-3.24]) and less likely to receive physical therapy (aHR 0.73 [0.64-0.85)], dementia medications (aHR 0.90 [0.86-0.95]), or Parkinson disease medications (aHR 0.88 [0.75-1.02]) within the last year of life. Black decedents were more likely to be hospitalized (aHR 1.28 [1.25-1.32]), more likely to be admitted to skilled nursing (aHR 1.09 [1.05-1.13]), and less likely to be admitted to hospice (aHR 0.82 [0.79-0.85]) than White decedents. Discussion: We found racial disparities in care utilization among patients with neurodegenerative disease in the last year of life, such that Black decedents were more likely to receive specific low-value care services and less likely to receive high-value supportive care than White decedents, even after adjusting for health status and socioeconomic factors.

WALL-ASSOCIATED KINASE Like 14 regulates vascular tissue development in Arabidopsis and tomato.

Initiation of plant vascular tissue is regulated by transcriptional networks during development and in response to environmental stimuli. The WALL-ASSOCIATED KINASES (WAKs) and WAK-likes (WAKLs) are cell surface receptors involved in cell expansion and defence in cells with primary walls, yet their roles in regulation of vascular tissue development that contain secondary walls remains unclear. In this study, we showed tomato (Solanum lycopersicum) SlWAKL2 and the orthologous gene in Arabidopsis thaliana, AtWAKL14, were specifically expressed in vascular tissues. SlWAKL2-RNAi tomato plants displayed smaller fruit size with fewer seeds and vascular bundles compared to wild-type (WT) and over-expression (OE) lines. RNA-seq data showed that SlWAKL2-RNAi fruits down-regulated transcript levels of genes related to vascular tissue development compared to WT. Histological analysis showed T-DNA insertion mutant wakl14-1 had reduced plant stem length with fewer number of xylem vessels and interfascicular fibres compared to WT, with no significant differences in cellulose and lignin content. Mutant wakl14-1 also showed reduced number of vascular bundles in fruit. A proWAKL14::mCherry-WAKL14 fusion protein was able to complement wakl14-1 phenotypes and showed mCherry-WAKL14 associated with the plasma membrane. In vitro binding assays showed both SlWAKL2 and AtWAKL14 can interact with pectin and oligogalacturonides. Our results reveal novel roles of WAKLs in regulating vascular tissue development.

Peripapillary Optical Coherence Tomography Angiography in Alzheimer's Disease, Mild Cognitive Impairment, and Normal Cognition.

OBJECTIVE: This study aimed to identify peripapillary microvascular changes in Alzheimer's disease (AD) and mild cognitive impairment (MCI). PATIENTS AND METHODS: In this prospective study, 66 eyes of 36 subjects with AD, 119 eyes of 63 with MCI, and 513 eyes of 265 controls with normal cognition were enrolled. Peripapillary capillary perfusion density (CPD), capillary flux index (CFI), and retinal nerve fiber layer (RNFL) thickness were determined. RESULTS: Average CPD differed significantly between all three groups (P = 0.001), being significantly greater in AD vs controls (0.446 ± 0.015 vs 0.439 ± 0.017, P = 0.001) and MCI vs controls (0.443 ± 0.020 vs 0.439 ± 0.017, P = 0.007) but not AD vs MCI (P = 0.69). CFI and average RNFL thickness did not significantly differ among groups (all P > 0.05). CONCLUSION: Peripapillary CPD is increased in eyes with AD or MCI compared to controls despite similar RNFL thickness. [Ophthalmic Surg Lasers Imaging Retina 2024;55:78-84.].

Structural changes in cell wall pectic polymers contribute to freezing tolerance induced by cold acclimation in plants.

Subzero temperatures are often lethal to plants. Many temperate herbaceous plants have a cold acclimation mechanism that allows them to sense a drop in temperature and prepare for freezing stress through accumulation of soluble sugars and cryoprotective proteins. As ice formation primarily occurs in the apoplast (the cell wall space), cell wall functional properties are important for plant freezing tolerance. Although previous studies have shown that the amounts of constituent sugars of the cell wall, in particular those of pectic polysaccharides, are altered by cold acclimation, the significance of this change during cold acclimation has not been clarified. We found that ß-1,4-galactan, which forms neutral side chains of the acidic pectic rhamnogalacturonan-I, accumulates in the cell walls of Arabidopsis and various freezing-tolerant vegetables during cold acclimation. The gals1 gals2 gals3 triple mutant, which has reduced ß-1,4-galactan in the cell wall, exhibited impaired freezing tolerance compared with wild-type Arabidopsis during initial stages of cold acclimation. Expression of genes involved in the galactan biosynthesis pathway, such as galactan synthases and UDP-glucose 4-epimerases, was induced during cold acclimation in Arabidopsis, explaining the galactan accumulation. Cold acclimation resulted in a decrease in extensibility and an increase in rigidity of the cell wall in the wild type, whereas these changes were not observed in the gals1 gals2 gals3 triple mutant. These results indicate that the accumulation of pectic ß-1,4-galactan contributes to acquired freezing tolerance by cold acclimation, likely via changes in cell wall mechanical properties.

Community Engagement Strategies for Underrepresented Racial and Ethnic Populations.

The representation of racial and ethnic minority populations in clinical trials continues to be a challenge despite mandates, good intentions, and concerted efforts by funding agencies, regulatory bodies, and researchers to close the clinical trials gap. A lack of diversity in research results in both continued disparities and poorer health outcomes. It is thus imperative that investigators understand and effectively address the challenges of clinical trials participation by underrepresented populations. In this paper, we expound on best practices for participatory research by clearly defining the community, highlighting the importance of proper identification and engagement of strong community partners, and exploring patient- and provider-level barriers and facilitators that require consideration. A clearer understanding of the balance of power between researchers and community partners is needed for any approach that addresses clinical trials representation. Unintended biases in study design and methods may continue to prevent racial and ethnic minority participants from taking part, and significant organizational changes are necessary for efficient and transparent relationships. Comprehensive community engagement in research includes dissemination of clinical trial results within and in partnership with community partners. Through careful deliberation and honest reflection, investigators, institutions, and community partners can develop the tailored blueprints of research collaborations essential for true equity in clinical trials.

Differences in Retinal and Choroidal Microvasculature and Structure in Dementia With Lewy Bodies Compared With Normal Cognition.

Purpose: To evaluate the retinal and choroidal microvasculature and structure in individuals with dementia with Lewy bodies (DLB) compared with controls with normal cognition using optical coherence tomography (OCT) and OCT angiography (OCTA). Methods: An institutional review board-approved cross-sectional comparison of patients with DLB and cognitively normal controls was performed. The Cirrus HD-OCT 5000 with AngioPlex (Carl Zeiss Meditec) was used to obtain OCT and OCTA images. Results: Thirty-four eyes of 18 patients with DLB and 85 eyes of 48 cognitively normal patients were analyzed. The average capillary perfusion density (CPD) was higher in the DLB group than in the control group (P = .005). The average capillary flux index (CFI) and ganglion cell inner-plexiform layer (GC-IPL) thickness were lower in the DLB group than in the control group (P = .016 and P = .040, respectively). Conclusions: Patients with DLB had an increased peripapillary CPD, decreased peripapillary CFI, and attenuated GC-IPL thickness compared with those with normal cognition.

Community health worker training to reduce mental health and substance use stigma towards patients who have disengaged from HIV/TB care in South Africa: protocol for a stepped wedge hybrid type II pilot implementation trial.

BACKGROUND: South Africa has deployed community health workers (CHWs) to support individuals to enter and stay in HIV/TB care. Although CHWs routinely encounter patients with mental health (particularly depression) and substance use (SU) conditions that impact their engagement in HIV/TB care, CHWs are rarely trained in how to work with these patients. This contributes to mental health and SU stigma among CHWs, a known barrier to patient engagement in care. Mental health and SU training interventions could reduce CHW stigma and potentially improve patient engagement in care, but evidence of the feasibility, acceptability, and preliminary effectiveness of these interventions is scarce. Therefore, we designed a hybrid type 2 effectiveness-implementation pilot trial to evaluate the implementation and preliminary effectiveness of a CHW training intervention for reducing depression and SU stigma in the Western Cape, South Africa. METHODS: This stepped wedge pilot trial will engage CHWs from six primary care clinics offering HIV/TB care. Clinics will be block randomized into three-step cohorts that receive the intervention at varying time points. The Siyakhana intervention involves 3 days of training in depression and SU focused on psychoeducation, evidence-based skills for working with patients, and self-care strategies for promoting CHW wellness. The implementation strategy involves social contact with people with lived experience of depression/SU during training (via patient videos and a peer trainer) and clinical supervision to support CHWs to practice new skills. Both implementation outcomes (acceptability, feasibility, fidelity) and preliminary effectiveness of the intervention on CHW stigma will be assessed using mixed methods at 3- and 6-month follow-up assessments. DISCUSSION: This trial will advance knowledge of the feasibility, acceptability, and preliminary effectiveness of a CHW training for reducing depression and SU stigma towards patients with HIV and/or TB. Study findings will inform a larger implementation trial to evaluate the longer-term implementation and effectiveness of this intervention for reducing CHW stigma towards patients with depression and SU and improving patient engagement in HIV/TB care. TRIAL REGISTRATION: ClinicalTrials.gov NCT05282173. Registered on 7 March 2022.

Depth- and curvature-based quantitative susceptibility mapping analyses of cortical iron in Alzheimer's disease.

In addition to amyloid beta plaques and neurofibrillary tangles, Alzheimer's disease (AD) has been associated with elevated iron in deep gray matter nuclei using quantitative susceptibility mapping (QSM). However, only a few studies have examined cortical iron, using more macroscopic approaches that cannot assess layer-specific differences. Here, we conducted column-based QSM analyses to assess whether AD-related increases in cortical iron vary in relation to layer-specific differences in the type and density of neurons. We obtained global and regional measures of positive (iron) and negative (myelin, protein aggregation) susceptibility from 22 adults with AD and 22 demographically matched healthy controls. Depth-wise analyses indicated that global susceptibility increased from the pial surface to the gray/white matter boundary, with a larger slope for positive susceptibility in the left hemisphere for adults with AD than controls. Curvature-based analyses indicated larger global susceptibility for adults with AD versus controls; the right hemisphere versus left; and gyri versus sulci. Region-of-interest analyses identified similar depth- and curvature-specific group differences, especially for temporo-parietal regions. Finding that iron accumulates in a topographically heterogenous manner across the cortical mantle may help explain the profound cognitive deterioration that differentiates AD from the slowing of general motor processes in healthy aging.

Promoter and domain structures regulate FLA12 function during Arabidopsis secondary wall development.

Introduction: Fasciclin-like arabinogalactan-proteins (FLAs) are a family of multi-domain glycoproteins present at the cell surface and walls of plants. Arabidopsis thaliana FLA12 and homologs in cotton, Populus, and flax have been shown to play important functions regulating secondary cell wall (SCW) development. FLA12 has been shown to have distinct roles from the closely related FLA11 that also functions during SCW development. The promoter and domain features of FLA12 that regulate functional specificity have not been well characterized. Methods: In this study, promoter swap experiments of FLA11 and FLA12 were investigated. Mutation of proposed functional regions within FLA12 were used to investigate the role of post-translational modifications on sub-cellular location and trafficking. Domain swap experiments between FLA11 and FLA12 were performed to identify regions of functional specificity. Results: Promote swap experiments showed that FLA12 is differentially expressed in both stem and rosette leaves compared to FLA11. Post-translational modifications, in particular addition of the glycosylphosphatidylinositol-anchor (GPI-anchor), were shown to be important for FLA12 location at the plasma membrane (PM)/cell wall interface. Domain swap experiments between FLA11 and FLA12 showed that the C-terminal arabinogalactan (AG) glycan motif acts as a key regulatory region differentiating FLA12 functions from FLA11. Discussion: Understanding of FLA12 promoter and functional domains has provided new insights into the regulation of SCW development and functional specificity of FLAs for plant growth and development.

Dementia and Parkinson's disease diagnoses in electronic health records vs. Medicare claims data: a study of 101,980 linked patients.

BACKGROUND: Medicare claims and electronic health record data are both commonly used for research and clinical practice improvement; however, it is not known how concordant diagnoses of neurodegenerative diseases (NDD, comprising dementia and Parkinson's disease) are in these data types. Therefore, our objective was to determine the sensitivity and specificity of neurodegenerative disease (NDD) diagnoses contained in structured electronic health record (EHR) data compared to Medicare claims data. METHODS: This was a retrospective cohort study of 101,980 unique patients seen at a large North Carolina health system between 2013-2017, which were linked to 100% North and South Carolina Medicare claims data, to evaluate the accuracy of diagnoses of neurodegenerative diseases in EHRs compared to Medicare claims data. Patients age > 50 who were enrolled in fee-for-service Medicare were included in the study. Patients were classified as having or not having NDD based on the presence of validated ICD-CM-9 or ICD-CM-10 codes associated with NDD or claims for prescription drugs used to treat NDD. EHR diagnoses were compared to Medicare claims diagnoses. RESULTS: The specificity of any EHR diagnosis of NDD was 99.0%; sensitivity was 61.3%. Positive predictive value and negative predictive value were 90.8% and 94.1% respectively. Specificity of an EHR diagnosis of dementia was 99.0%, and sensitivity was 56.1%. Specificity of an EHR diagnosis of PD was 99.7%, while sensitivity was 76.1%. CONCLUSIONS: More research is needed to investigate under-documentation of NDD in electronic health records relative to Medicare claims data, which has major implications for clinical practice (particularly patient safety) and research using real-world data.

A blood biomarker test for brain amyloid impacts the clinical evaluation of cognitive impairment.

OBJECTIVE: The objective of this study was to examine clinicians' patient selection and result interpretation of a clinically validated mass spectrometry test measuring amyloid beta and ApoE blood biomarkers combined with patient age (PrecivityAD® blood test) in symptomatic patients evaluated for Alzheimer's disease (AD) or other causes of cognitive decline. METHODS: The Quality Improvement and Clinical Utility PrecivityAD Clinician Survey (QUIP I, ClinicalTrials.gov Identifier: NCT05477056) was a prospective, single-arm cohort study among 366 patients evaluated by neurologists and other cognitive specialists. Participants underwent blood biomarker testing and received an amyloid probability score (APS), indicating the likelihood of a positive result on an amyloid positron emission tomography (PET) scan. The primary study outcomes were appropriateness of patient selection as well as result interpretation associated with PrecivityAD blood testing. RESULTS: A 95% (347/366) concordance rate was noted between clinicians' patient selection and the test's intended use criteria. In the final analysis including these 347 patients (median age 75 years, 56% women), prespecified test result categories incorporated 133 (38%) low APS, 162 (47%) high APS, and 52 (15%) intermediate APS patients. Clinicians' pretest and posttest AD diagnosis probability changed from 58% to 23% in low APS patients and 71% to 89% in high APS patients (p < 0.0001). Anti-AD drug therapy decreased by 46% in low APS patients (p < 0.0001) and increased by 57% in high APS patients (p < 0.0001). INTERPRETATION: These findings demonstrate the clinical utility of the PrecivityAD blood test in clinical care and may have added relevance as new AD therapies are introduced.

Comparative genomics of flowering behavior in Cannabis sativa.

Cannabis sativa L. is a phenotypically diverse and multi-use plant used in the production of fiber, seed, oils, and a class of specialized metabolites known as phytocannabinoids. The last decade has seen a rapid increase in the licit cultivation and processing of C. sativa for medical end-use. Medical morphotypes produce highly branched compact inflorescences which support a high density of glandular trichomes, specialized epidermal hair-like structures that are the site of phytocannabinoid biosynthesis and accumulation. While there is a focus on the regulation of phytocannabinoid pathways, the genetic determinants that govern flowering time and inflorescence structure in C. sativa are less well-defined but equally important. Understanding the molecular mechanisms that underly flowering behavior is key to maximizing phytocannabinoid production. The genetic basis of flowering regulation in C. sativa has been examined using genome-wide association studies, quantitative trait loci mapping and selection analysis, although the lack of a consistent reference genome has confounded attempts to directly compare candidate loci. Here we review the existing knowledge of flowering time control in C. sativa, and, using a common reference genome, we generate an integrated map. The co-location of known and putative flowering time loci within this resource will be essential to improve the understanding of C. sativa phenology.

Elongated galactan side chains mediate cellulose-pectin interactions in engineered Arabidopsis secondary cell walls.

The plant secondary cell wall is a thickened matrix of polysaccharides and lignin deposited at the cessation of growth in some cells. It forms the majority of carbon in lignocellulosic biomass, and it is an abundant and renewable source for forage, fiber, materials, fuels, and bioproducts. The complex structure and arrangement of the cell wall polymers mean that the carbon is difficult to access in an economical and sustainable way. One solution is to alter the cell wall polymer structure so that it is more suited to downstream processing. However, it remains difficult to predict what the effects of this engineering will be on the assembly, architecture, and properties of the cell wall. Here, we make use of Arabidopsis plants expressing a suite of genes to increase pectic galactan chain length in the secondary cell wall. Using multi-dimensional solid-state nuclear magnetic resonance, we show that increasing galactan chain length enhances pectin-cellulose spatial contacts and increases cellulose crystallinity. We also found that the increased galactan content leads to fewer spatial contacts of cellulose with xyloglucan and the backbone of pectin. Hence, we propose that the elongated galactan side chains compete with xyloglucan and the pectic backbone for cellulose interactions. Due to the galactan topology, this may result in comparatively weak interactions and disrupt the cell wall architecture. Therefore, introduction of this strategy into trees or other bioenergy crops would benefit from cell-specific expression strategies to avoid negative effects on plant growth.

Arabinogalactan proteins - Multifunctional glycoproteins of the plant cell wall.

Arabinogalactan-proteins (AGPs) are cell wall glycoproteins that make up a relatively small component of the extracellular matrix of plants yet have significant influence on wall mechanics and signalling. Present in walls of algae, bryophytes and angiosperms, AGPs have a wide range of functional roles, from signalling, cell expansion and division, embryogenesis, responses to abiotic and biotic stress, plant growth and development. AGPs interact with and influence wall matrix components and plasma membrane proteins to regulate developmental pathways and growth responses, yet the exact mechanisms remain elusive. Comprising a large gene family that is highly diverse, from minimally to highly glycosylated members, varying in their glycan heterogeneity, can be plasma membrane bound or secreted into the extracellular matrix, have members that are highly tissue specific to those with constitutive expression; all these factors have made it extremely challenging to categorise AGPs many qualities and roles. Here we attempt to define some key features of AGPs and their biological functions.

Patient and stakeholder perspectives on impacts of the COVID-19 pandemic on HIV and mental health care delivery in South Africa.

BACKGROUND: The COVID-19 pandemic had a global impact on health systems and the delivery of health services, including for chronic conditions such as HIV. In South Africa, impacts on HIV services have widely been quantitatively described. Across different health settings, patients have also qualitatively described numerous negative impacts to their HIV care. However, patient perspectives on COVID-19 impacts to HIV care in South Africa, the largest HIV care system in the world, have been little explored to date. METHODS: We conducted 29 semi-structured individual interviews with people living with HIV (n = 24) and providers (n = 5) in Cape Town, South Africa. RESULTS: While most patient participants reported continued access to HIV treatment during the pandemic, many described perceiving that the quality of their care declined. Increased structural barriers were described as one contributing factor to this change. Additionally, patients described that reduced privacy in clinical interactions was a key factor negatively influencing their experience of receiving care. CONCLUSION: Findings underscore the importance of ensuring patient privacy for HIV services even during the rearrangement of services in emergencies. It is also important to continue developing models to integrate community mental health services within HIV care delivery in South Africa.