Explore the vast range of titles available.

This multidisciplinary scientific monograph provides the first exhaustive ecological assessment of Abu Al Abyad, the largest offshore island in the Emirate of Abu Dhabi. Written by a team of ten specialists, the work documents a unique \"living laboratory\" where traditional desert ecosystems meet managed conservation efforts. The study is particularly significant for its record of the island’s transformation from a barren landscape into a thriving sanctuary for indigenous and exotic wildlife under the patronage of the UAE leadership.

A growing body of research is investigating the potential contribution of mitochondrial function to the etiology of type 2 diabetes. Numerous in vitro, in situ, and in vivo methodologies are available to examine various aspects of mitochondrial function, each requiring an understanding of their principles, advantages, and limitations. This review provides investigators with a critical overview of the strengths, limitations and critical experimental parameters to consider when selecting and conducting studies on mitochondrial function. In vitro (isolated mitochondria) and in situ (permeabilized cells/tissue) approaches provide direct access to the mitochondria, allowing for study of mitochondrial bioenergetics and redox function under defined substrate conditions. Several experimental parameters must be tightly controlled, including assay media, temperature, oxygen concentration, and in the case of permeabilized skeletal muscle, the contractile state of the fibers. Recently developed technology now offers the opportunity to measure oxygen consumption in intact cultured cells. Magnetic resonance spectroscopy provides the most direct way of assessing mitochondrial function in vivo with interpretations based on specific modeling approaches. The continuing rapid evolution of these technologies offers new and exciting opportunities for deciphering the potential role of mitochondrial function in the etiology and treatment of diabetes.

In Duchenne muscular dystrophy, a lack of dystrophin leads to extensive muscle weakness and atrophy that is linked to cellular metabolic dysfunction and oxidative stress. This dystrophinopathy results in a loss of tethering between microtubules and the sarcolemma. Microtubules are also believed to regulate mitochondrial bioenergetics potentially by binding the outer mitochondrial membrane voltage dependent anion channel (VDAC) and influencing permeability to ADP/ATP cycling. The objective of this investigation was to determine if a lack of dystrophin causes microtubule disorganization concurrent with mitochondrial dysfunction in skeletal muscle, and whether this relationship is linked to altered binding of tubulin to VDAC. In extensor digitorum longus (EDL) muscle from 4-week old D2.mdx mice, microtubule disorganization was observed when probing for [alpha]-tubulin. This cytoskeletal disorder was associated with a reduced ability of ADP to stimulate respiration and attenuate H.sub.2 O.sub.2 emission relative to wildtype controls. However, this was not associated with altered [alpha]-tubulin-VDAC2 interactions. These findings reveal that microtubule disorganization in dystrophin-deficient EDL is associated with impaired ADP control of mitochondrial bioenergetics, and suggests that mechanisms alternative to [alpha]-tubulin's regulation of VDAC2 should be examined to understand how cytoskeletal disruption in the absence of dystrophin may cause metabolic dysfunctions in skeletal muscle.

PurposeTo examine the relationship between changes in nuclear factor erythroid 2-related factor 2 (Nrf2) expression and markers of mitochondrial biogenesis in acutely and chronically exercised human skeletal muscle.MethodsThe impact of acute submaximal endurance (END) and supramaximal interval (Tabata) cycling on the upregulation of Nrf2 (and its downstream targets), nuclear respiratory factor-1 (NRF-1) and mitochondrial transcription factor A (TFAM) mRNA expression was examined in healthy young males (n = 10). The relationship between changes in citrate synthase (CS) maximal activity and the protein content of Nrf2, heme oxygenase 1 (HO-1), NRF-1, and TFAM was also investigated following 4 weeks of Tabata in a separate group of males (n = 21).ResultsNrf2, NRF-1, and HO-1 mRNA expression increased after acute exercise (p < 0.05), whereas the increase in superoxide dismutase 2 (SOD2) mRNA expression approached significance (p = 0.08). Four weeks of Tabata increased CS activity and Nrf2, NRF-1, and TFAM protein content (p < 0.05), but decreased HO-1 protein content (p < 0.05). Training-induced changes in Nrf2 protein were strongly correlated with NRF-1 (r = 0.63, p < 0.01). When comparing protein content changes between individuals with the largest (HI: + 23%) and smallest (LO: − 1%) observed changes in CS activity (n = 8 each), increases in Nrf2 and TFAM protein content were apparent in the HI group only (p < 0.02) with medium-to-large effect sizes for between-group differences in changes in Nrf2 (ηp2=0.15) and TFAM (ηp2 = 0.12) protein content.ConclusionAltogether, our findings support a potential role for Nrf2 in exercise-induced mitochondrial biogenesis in human skeletal muscle.

Individuals with type 1 diabetes (T1D) experience a complex set of alterations to skeletal muscle metabolic, neuromuscular, and vascular health; collectively referred to as diabetic myopathy. While the full scope of diabetic myopathy is still being elucidated, evidence suggests that even when individuals with T1D are physically active, indices of myopathy still exist. As such, there is a question if adherence to current physical activity guidelines elicits improvements in skeletal muscle health indices similarly between individuals with and without T1D. The objectives of this trial are to: 1) compare baseline differences in skeletal muscle health between adults with and without T1D, 2) examine the association between participation in a home-based exercise program, detraining, and retraining, with changes in skeletal muscle health, and 3) examine the roles of age and sex on these associations. This will be a prospective interventional trial. Younger (18-30 years) and older (45-65 years) males and females with T1D and matched individuals without T1D will engage in a four-phase, 18-week study sequentially consisting of a one-week lead-in period, 12-week exercise training program, one-week detraining period, and four-week retraining period. The exercise program will consist of aerobic and resistance exercise based on current guidelines set by Diabetes Canada. Metabolic, neuromuscular, and vascular outcome measures will be assessed four times: at baseline, post-exercise program, post-detraining, and post-retraining. Differences in baseline metrics between those with and without T1D will be examined with independent sample t-tests, and with two-way analyses of variance for age- and sex-stratified analyses. Changes across the duration of the study will be examined using mixed-model analyses. Findings from this research will be shared locally and internationally with research participants, clinicians, diabetes educators, and patient advocacy organizations via in-person presentations, social media, and scientific fora. NCT05740514.

Background/Objectives: Chronic exercise training reduces markers of systemic inflammation; however, less is known about how to optimize this adaptation using nutrition. Dairy products, especially fermented ones, like Greek yogurt (GY), contain anti-inflammatory constituents. This secondary analysis aimed to examine the influence of post-exercise GY consumption vs. an isoenergetic carbohydrate pudding (CP; control) on markers of systemic inflammation during an exercise training intervention. Methods: Thirty healthy young males completed 12 weeks of resistance and plyometric exercise training and were randomized to consume GY (n = 15) or CP (n = 15). Rested/fasted blood samples were acquired at baseline, and weeks 1 and 12, and inflammatory biomarkers (tumor necrosis factor-alpha [TNF-α], interleukin [IL]-6, IL-1 receptor antagonist [IL-1ra], IL-1Beta [IL-1β], IL-10, and C-reactive protein [CRP]) were measured. Linear mixed models were run on the absolute concentrations, and linear regressions were performed on the absolute change (baseline to week 12), allowing us to account for important covariates. Results: In both groups, CRP (pro) and IL-1ra (anti) increased at week 1 vs. baseline and week 12, while IL-1β (pro) decreased at week 12 vs. baseline (main time effects). We observed significant interactions for IL-6, TNF-α, and the TNF-α/IL-10 ratio, indicating that at week 12, IL-6 (pro) was lower in GY, whereas TNF-α and TNF-α/IL-10 (both pro-inflammatory) were higher in CP vs. week 1 and baseline, respectively. Additionally, within our linear regression models, higher baseline concentrations of IL-1ra (anti), IL-10 (anti) and CRP (pro) predicted greater change over the intervention. Conclusions: These results indicate that our intervention benefited circulating inflammatory markers, and GY supplementation may enhance these effects.

The effect of biological sex on rates of skeletal muscle mitochondrial respiration supported by creatine‐dependent phosphate shuttling was previously unknown. The aim of this investigation was to test the hypothesis that females and males matched for peak oxygen uptake normalized to fat‐free mass would not exhibit differences in rates of mass‐specific and intrinsic mitochondrial respiration in the presence or absence of creatine. Rates of mass‐specific and intrinsic complex I (pyruvate and malate)‐ and complex I+II‐supported, adenosine diphosphate (ADP)‐stimulated mitochondrial respiration in the presence and absence of 20 mM creatine were measured via high‐resolution respirometry. Total, intermyofibrillar and subsarcolemmal mitochondrial volume density were analysed using transmission electron microscopy. Rates of intrinsic mitochondrial respiration were obtained by normalizing mass‐specific respiration rates to total mitochondrial volume density and total electron transport chain subunit protein content. Overall, there was no effect of sex on rates of mass‐specific or intrinsic mitochondrial respiration in the presence or absence of creatine. There was also no effect of sex on total, intermyofibrillar and subsarcolemmal mitochondrial volume density or electron transport chain subunit protein content. Our data demonstrate an overall lack of sex‐based differences in rates of intrinsic complex I‐ and complex I+II‐supported, ADP‐stimulated mitochondrial respiration in the presence or absence of creatine in females and males matched for aerobic fitness. Thus, biological sex per se does not appear to modulate intrinsic skeletal muscle mitochondrial respiration in healthy young adults. What is the central question of this study? Mitochondrial–cytosolic energy exchange can occur via creatine‐dependent and ‐independent mechanisms, but whether biological sex impacts rates of intrinsic mitochondrial respiration in the presence of creatine in human skeletal muscle remains unknown. What is the main finding and its importance? Biological sex does not impact mitochondrial volume density or intrinsic mitochondrial respiration supported by creatine‐dependent phosphate shuttling and creatine‐independent ADP diffusion when females and males are matched for peak oxygen uptake normalized to fat‐free mass. Matching females and males for aerobic fitness mitigates sex differences in rates of mitochondrial respiration and mitochondrial content in humans.

Lipocalin-2 (Lcn2), a critical component of the innate immune response which binds siderophores and limits bacterial iron acquisition, can elicit spillover adverse proinflammatory effects. Here we show that holo-Lcn2 (Lcn2–siderophore–iron, 1:3:1) increases mitochondrial reactive oxygen species (ROS) generation and attenuates mitochondrial oxidative phosphorylation in adult rat primary cardiomyocytes in a manner blocked by N-acetyl-cysteine or the mitochondria-specific antioxidant SkQ1. We further demonstrate using siderophores 2,3-DHBA (2,3-dihydroxybenzoic acid) and 2,5-DHBA that increased ROS and reduction in oxidative phosphorylation are direct effects of the siderophore component of holo-Lcn2 and not due to apo-Lcn2 alone. Extracellular apo-Lcn2 enhanced the potency of 2,3-DHBA and 2,5-DHBA to increase ROS production and decrease mitochondrial respiratory capacity, whereas intracellular apo-Lcn2 attenuated these effects. These actions of holo-Lcn2 required an intact plasma membrane and were decreased by inhibition of endocytosis. The hearts, but not serum, of Lcn2 knockout (LKO) mice contained lower levels of 2,5-DHBA compared with wild-type hearts. Furthermore, LKO mice were protected from ischemia/reperfusion-induced cardiac mitochondrial dysfunction. Our study identifies the siderophore moiety of holo-Lcn2 as a regulator of cardiomyocyte mitochondrial bioenergetics.

Lentiviral vectors (LVs) are potent tools for the delivery of genes of interest into mammalian cells and are now commonly utilised within the growing field of cell and gene therapy for the treatment of monogenic diseases and adoptive therapies such as chimeric antigen T-cell (CAR-T) therapy. This is a comprehensive review of the individual bioprocess operations employed in LV production. We highlight the role of envelope proteins in vector design as well as their impact on the bioprocessing of lentiviral vectors. An overview of the current state of these operations provides opportunities for bioprocess discovery and improvement with emphasis on the considerations for optimal and scalable processing of LV during development and clinical production. Upstream culture for LV generation is described with comparisons on the different transfection methods and various bioreactors for suspension and adherent producer cell cultivation. The purification of LV is examined, evaluating different sequences of downstream process operations for both small- and large-scale production requirements. For scalable operations, a key focus is the development in chromatographic purification in addition to an in-depth examination of the application of tangential flow filtration. A summary of vector quantification and characterisation assays is also presented. Finally, the assessment of the whole bioprocess for LV production is discussed to benefit from the broader understanding of potential interactions of the different process options. This review is aimed to assist in the achievement of high quality, high concentration lentiviral vectors from robust and scalable processes.

Aims/hypothesisThis study interrogated mitochondrial respiratory function and content in skeletal muscle biopsies of healthy adults between 30 and 72 years old with and without uncomplicated type 1 diabetes.MethodsParticipants (12 women/nine men) with type 1 diabetes (48 ± 11 years of age), without overt complications, were matched for age, sex, BMI and level of physical activity to participants without diabetes (control participants) (49 ± 12 years of age). Participants underwent a Bergström biopsy of the vastus lateralis to assess mitochondrial respiratory function using high-resolution respirometry and citrate synthase activity. Electron microscopy was used to quantify mitochondrial content and cristae (pixel) density.ResultsMean mitochondrial area density was 27% lower (p = 0.006) in participants with type 1 diabetes compared with control participants. This was largely due to smaller mitochondrial fragments in women with type 1 diabetes (−18%, p = 0.057), as opposed to a decrease in the total number of mitochondrial fragments in men with diabetes (−28%, p = 0.130). Mitochondrial respiratory measures, whether estimated per milligram of tissue (i.e. mass-specific) or normalised to area density (i.e. intrinsic mitochondrial function), differed between cohorts, and demonstrated sexual dimorphism. Mass-specific mitochondrial oxidative phosphorylation (OXPHOS) capacity with the substrates for complex I and complex II (CI + II) was significantly lower (−24%, p = 0.033) in women with type 1 diabetes compared with control participants, whereas mass-specific OXPHOS capacities with substrates for complex I only (pyruvate [CI pyr] or glutamate [CI glu]) or complex II only (succinate [CII succ]) were not different (p > 0.404). No statistical differences (p > 0.397) were found in mass-specific OXPHOS capacity in men with type 1 diabetes compared with control participants despite a 42% non-significant increase in CI glu OXPHOS capacity (p = 0.218). In contrast, intrinsic CI + II OXPHOS capacity was not different in women with type 1 diabetes (+5%, p = 0.378), whereas in men with type 1 diabetes it was 25% higher (p = 0.163) compared with control participants. Men with type 1 diabetes also demonstrated higher intrinsic OXPHOS capacity for CI pyr (+50%, p = 0.159), CI glu (+88%, p = 0.033) and CII succ (+28%, p = 0.123), as well as higher intrinsic respiratory rates with low (more physiological) concentrations of either ADP, pyruvate, glutamate or succinate (p < 0.012). Women with type 1 diabetes had higher (p < 0.003) intrinsic respiratory rates with low concentrations of succinate only. Calculated aerobic fitness (Physical Working Capacity Test [PWC130]) showed a strong relationship with mitochondrial respiratory function and content in the type 1 diabetes cohort.Conclusions/interpretationIn middle- to older-aged adults with uncomplicated type 1 diabetes, we conclude that skeletal muscle mitochondria differentially adapt to type 1 diabetes and demonstrate sexual dimorphism. Importantly, these cellular alterations were significantly associated with our metric of aerobic fitness (PWC130) and preceded notable impairments in skeletal mass and strength.