Social Isolation in Community-Dwelling Older Adults During COVID-19: Understanding the Role of Resilience.

The COVID-19 pandemic increased social isolation for many older adults, causing concern for their health and well-being. To enhance understanding of how community-dwelling older adults were impacted by prolonged social isolation during COVID-19, a qualitative descriptive study was conducted to: (1) explore the self-reported factors supporting their resilience during COVID-19 related social isolation, and (2) to help understand the intentional and unintentional outcomes of the government mandated health measures. A total of 19 community dwelling older adults were sampled. Factors that supported older adults' resilience during COVID-19 included maintaining positivity, drawing on historical experiences of resilience and finding opportunities to connect with their community. However, collective safety came with losses: such as time, freedom, opportunity, engagement, and initiative. The findings provide insight on contributing factors to resilience against social isolation in older adults and suggest the value of collective, community-based approaches to build resilience across variable contexts in this population.

Pre-operative respiratory assessment for children with spinal deformity.

Pre-operative respiratory assessment of children with spinal deformity requires an understanding of the deformity, the proposed surgery and most importantly the children themselves. The assessment and the tailoring of investigations will differ according to the age, developmental level and co-morbidities of the child. This review uses a mixture of evidence and case-based practice in order to set out a suggested framework for pre-operative spinal assessment, and suggested recommendations that may be provided to best support children undergoing surgery for spinal deformity.

The loss of Sirt1 in mouse pancreatic beta cells impairs insulin secretion by disrupting glucose sensing.

AIMS/HYPOTHESIS: Sirtuin 1 (SIRT1) has emerged as a key metabolic regulator of glucose homeostasis and insulin secretion. Enhanced SIRT1 activity has been shown to be protective against diabetes, although the mechanisms remain largely unknown. The aim of this study was to determine how SIRT1 regulates insulin secretion in the pancreatic beta cell. METHODS: Pancreatic beta cell-specific Sirt1 deletion was induced by tamoxifen injection in 9-week-old Pdx1CreER:floxSirt1 mice (Sirt1BKO). Controls were injected with vehicle. Mice were assessed metabolically via glucose challenge, insulin tolerance tests and physical variables. In parallel, Sirt1 short interfering RNA-treated MIN6 cells (SIRT1KD) and isolated Sirt1BKO islets were used to investigate the effect of SIRT1 inactivation on insulin secretion and gene expression. RESULTS: OGTTs showed impaired glucose disposal in Sirt1BKO mice due to insufficient insulin secretion. Isolated Sirt1BKO islets and SIRT1KD MIN6 cells also exhibited impaired glucose-stimulated insulin secretion. Subsequent analyses revealed impaired α-ketoisocaproic acid-induced insulin secretion and attenuated glucose-induced Ca(2+) influx, but normal insulin granule exocytosis in Sirt1BKO beta cells. Microarray studies revealed a large cluster of mitochondria-related genes, the expression of which was dysregulated in SIRT1KD MIN6 cells. Upon further analysis, we demonstrated an explicit defect in mitochondrial function: the inability to couple nutrient metabolism to mitochondrial membrane hyperpolarisation and reduced oxygen consumption rates. CONCLUSIONS/INTERPRETATION: Taken together, these findings indicate that in beta cells the deacetylase SIRT1 regulates the expression of specific mitochondria-related genes that control metabolic coupling, and that a decrease in beta cell Sirt1 expression impairs glucose sensing and insulin secretion.

Effects of high-fat diet feeding on Znt8-null mice: differences between ß-cell and global knockout of Znt8.

Genomewide association studies have linked a polymorphism in the zinc transporter 8 (Znt8) gene to higher risk of developing type 2 diabetes. Znt8 is highly expressed in pancreatic ß-cells where it is involved in the regulation of zinc transport into granules. However, Znt8 is also expressed in other tissues including α-cells, where its function is as yet unknown. Previous work demonstrated that mice lacking Znt8 globally were more susceptible to diet-induced obesity (Lemaire et al., Proc Natl Acad Sci USA 106: 14872-14877, 2009; Nicolson et al., Diabetes 58: 2070-2083, 2009). Therefore, the main goal of this study was to examine the physiological impact of ß-cell-specific Znt8 deficiency in mice during high-fat high-calorie (HFHC) diet feeding. For these studies, we used ß-cell-specific Znt8 knockout (Ins2Cre:Znt8loxP/loxP) and whole body Znt8 knockout (Cre-:Znt8(-/-)) mice placed on a HFHC diet for 16 wk. Ins2Cre:Znt8loxP/loxP mice on HFHC diet had similar body weights throughout the study but displayed impaired insulin biosynthesis and secretion and were glucose intolerant compared with littermate control Ins2Cre mice. In contrast, Cre-:Znt8(-/-) mice became remarkably obese, hyperglycemic, hyperinsulinemic, insulin resistant, and glucose intolerant compared with littermate control Cre- mice. These data show that ß-cell Znt8 alone does not considerably aggravate weight gain and glucose intolerance during metabolic stress imposed by an HFHC diet. However, global loss of Znt8 is involved in exacerbating diet-induced obesity and resulting insulin resistance, and this may be due to the loss of Znt8 activity in a tissue other than the ß-cell. Thus, our data suggest that Znt8 contributes to the risk of developing type 2 diabetes through ß-cell- and non-ß-cell-specific effects.

The functional and molecular characterisation of human embryonic stem cell-derived insulin-positive cells compared with adult pancreatic beta cells.

AIMS/HYPOTHESIS: Using a novel directed differentiation protocol, we recently generated up to 25% insulin-producing cells from human embryonic stem cells (hESCs) (insulin(+) cells). At this juncture, it was important to functionally and molecularly characterise these hESC-derived insulin(+) cells and identify key differences and similarities between them and primary beta cells. METHODS: We used a new reporter hESC line with green fluorescent protein (GFP) cDNA targeted to the INS locus by homologous recombination (INS (GFP/w)) and an untargeted hESC line (HES2). INS (GFP/w) allowed efficient identification and purification of GFP-producing (INS:GFP(+)) cells. Insulin(+) cells were examined for key features of adult beta cells using microarray, quantitative PCR, secretion assays, imaging and electrophysiology. RESULTS: Immunofluorescent staining showed complete co-localisation of insulin with GFP; however, cells were often multihormonal, many with granules containing insulin and glucagon. Electrophysiological recordings revealed variable K(ATP) and voltage-gated Ca(2+) channel activity, and reduced glucose-induced cytosolic Ca(2+) uptake. This translated into defective glucose-stimulated insulin secretion but, intriguingly, appropriate glucagon responses. Gene profiling revealed differences in global gene expression between INS:GFP(+) cells and adult human islets; however, INS:GFP(+) cells had remarkably similar expression of endocrine-lineage transcription factors and genes involved in glucose sensing and exocytosis. CONCLUSIONS/INTERPRETATION: INS:GFP(+) cells can be purified from differentiated hESCs, providing a superior source of insulin-producing cells. Genomic analyses revealed that INS:GFP(+) cells collectively resemble immature endocrine cells. However, insulin(+) cells were heterogeneous, a fact that translated into important functional differences within this population. The information gained from this study may now be used to generate new iterations of functioning beta cells that can be purified for transplant.

Incretin hormones and the expanding families of glucagon-like sequences and their receptors.

Peptide hormones encoded by the proglucagon (Gcg) and glucose-dependent insulinotropic polypeptide (Gip) genes are evolutionarily related glucagon-like sequences and act through a subfamily of G-protein-coupled receptors. A better understanding of the evolutionary history of these hormones and receptors should yield insight into their biological functions. The availability of a large number of near-complete vertebrate genome sequences is a powerful resource to address questions concerning the evolution of sequences; here, we utilize these resources to examine the evolution of glucagon-like sequences and their receptors. These studies led to the discovery of novel genes for a glucagon receptor-like receptor (Grlr) and a glucagon-like sequence (exendin) in vertebrates. Both exendin and GRLR have ancient origins, early in vertebrate evolution, but have been lost on the ancestral lineage leading to extant mammals. We also show that exendin and GRLR are both expressed in the brain of the chicken and Xenopus tropicals, results that suggest that the products of these genes function in this tissue. The lack of exendin or Grlr genes in mammals suggests that other genes may have acquired the functions of exendin and Grlr during mammalian evolution.

A Critical Evaluation of Interlaboratory Data on Total, Elemental, and Isotopic Carbon in the Carbonaceous Particle Reference Material, NIST SRM 1649a.

Because of increased interest in the marine and atmospheric sciences in elemental carbon (EC), or black carbon (BC) or soot carbon (SC), and because of the difficulties in analyzing or even defining this pervasive component of particulate carbon, it has become quite important to have appropriate reference materials for intercomparison and quality control. The NIST "urban dust" Standard Reference Material(®) SRM 1649a is useful in this respect, in part because it comprises a considerable array of inorganic and organic species, and because it exhibits a large degree of ((14)C) isotopic heterogeneity, with biomass carbon source contributions ranging from about 2 % (essentially fossil aliphatic fraction) to about 32 % (polar fraction). A primary purpose of this report is to provide documentation for the new isotopic and chemical particulate carbon data for the most recent (31 Jan. 2001) SRM 1649a Certificate of Analysis. Supporting this is a critical review of underlying international intercomparison data and methodologies, provided by 18 teams of analytical experts from 11 institutions. Key results of the intercomparison are: (1) a new, Certified Value for total carbon (TC) in SRM 1649a; (2) (14)C Reference Values for total carbon and a number of organic species, including for the first time 8 individual PAHs; and (3) elemental carbon (EC) Information Values derived from 13 analytical methods applied to this component. Results for elemental carbon, which comprised a special focus of the intercomparison, were quite diverse, reflecting the confounding of methodological-matrix artifacts, and methods that tended to probe more or less refractory regions of this universal, but ill-defined product of incomplete combustion. Availability of both chemical and (14)C speciation data for SRM 1649a holds great promise for improved analytical insight through comparative analysis (e.g., fossil/biomass partition in EC compared to PAH), and through application of the principle of isotopic mass balance.

An improved thermal oxidation method for the quantification of soot/graphitic black carbon in sediments and soils.

Recent findings have confirmed the importance of black carbon (BC) in the global biogeochemical cycles of carbon and oxygen through its important contribution to the slowly cycling organic carbon (OC) pool. Yet, most BC determination methods published to date measure operationally defined BC fractions, oftentimes with a high potential for artifacts and a lack of specificity for one of the two major forms of the BC continuum, soot/graphitic BC (GBC) and char/charcoal BC (CBC). This paper describes a method that reduces the potential for artifacts to accurately and selectively measure the concentration of GBC in complex mineral and organic matrixes. Marine and lacustrine sediments, river sediments, suspended particles, and a marine plankton sample were first demineralized with a mixture of hydrochloric (HCl) and hydrofluoric (HF) acids to expose any biochemical entrapped in a mineral matrix. The hydrolyzable organic matter fraction (mostly proteins and carbohydrates) was then removed with 02-free trifluoroacetic acid and HCl, after which the non-GBC, non-hydrolyzable OC fraction was finally removed by thermal oxidation at 375 degrees C for 24 h. The specificity of the method for GBC was assessed with pure CBC and GBC samples. Detection limit and GBC recovery in spiked samples were 10 mg kg(-1) and approximately 85%, respectively. Typical GBC concentrations measured in a series of natural samples ranged from <10 mg kg(-1) in marine plankton to 0.19% in a riverine sample. These concentrations were lower by as much as 3 orders of magnitude than those obtained by thermal oxidation without demineralization and removal of hydrolyzable organic matter. The improvements presented in this work allow for the accurate and precise measurement of GBC in complex organic and mineral matrixes by eliminating the interference caused by the presence of CBC, residual non-BC OC and minerals, or by the formation of condensation products that could account for as much as 4-6% of total OC. Combined to stable and radioisotope analysis, this improved method should permit quantitative assessments of the role and dynamics of GBC in the global geochemical cycles of carbon and oxygen.

Memory and encoding of spoken discourse following right hemisphere damage: evidence from the Auditory Moving Window (AMW) technique.

We investigated the hypotheses that impaired discourse processing following right hemisphere damage is mediated by task difficulty and is associated with deficits in discourse encoding. Spoken discourse passages differing in contextual predictability were presented to right hemisphere-damaged (RHD) patients and to non-brain-damaged (NBD) controls for subsequent recall using the Auditory Moving Window paradigm. To manipulate processing difficulty, speech segments were of normal or accelerated speech rates. The recall results showed that RHD adults recalled less than NBD controls overall and failed to recall major idea units better than minor idea units for high predictability passages presented at accelerated speech rates. Both RHD patients and NBD controls failed to recall major idea units better than minor idea units for low predictability passages, regardless of speech rate. The encoding results showed that RHD adults were both slower overall and differentially slower than NBD controls when listening to accelerated passage segments. Taken together, the encoding and recall results are consistent with the view that extracting passage gist under difficult listening conditions is especially vulnerable for patients with right hemisphere strokes.

Resource allocation during spoken discourse processing: effects of age and passage difficulty as revealed by self-paced listening.

The allocation of processing resources during spoken discourse comprehension was studied in a manner analogous to self-paced reading using the auditory moving window technique (Ferreira, Henderson, Anes, Weeks, & McFarlane, 1996). Young and older participants listened to spoken passages in a self-paced segment-by-segment fashion. In Experiment 1, we examined the influence of speech rate and passage complexity on discourse encoding and recall performance. In Experiment 2, we examined the influence of speech rate and presentation mode (self-paced vs. full-passage presentation) on recall performance. Results suggest that diminished memory performance in the older adult group relative to the young adult group is attributable to age-related differences in how resources were allocated during the initial encoding of the spoken discourse.