Temporal dynamics of fecal microbiota community succession in broiler chickens, calves, and piglets under aerobic exposure.

Researchers have extensively studied the effect of oxygen on the growth and survival of bacteria. However, the impact of oxygen on bacterial community structure, particularly its ability to select for taxa within the context of a complex microbial community, is still unclear. In a 21-day microcosm experiment, we investigated the effect of aerobic exposure on the fecal community structure and succession pattern in broiler, calf, and piglet feces (n = 10 for each feces type). Bacterial diversity decreased and community structure changed rapidly in the broiler microbiome (P < 0.001), while the fecal community of calves and piglets, which have higher initial diversity, was stable after initial exposure but decreased in diversity after 3 days (P < 0.001). The response to aerobic exposure was host animal specific, but in all three animals, the change in community structure was driven by a decrease in anaerobic species, primarily belonging to Firmicutes and Bacteroidetes (except in broilers where Bacteroidetes increased), along with an increase in aerobic species belonging to Proteobacteria and Actinobacteria. Using random forest regression, we identified microbial features that predict aerobic exposure. In all three animals, host-beneficial Prevotella-related ASVs decreased after exposure, while ASVs belonging to Acinetobacter, Corynbacterium, and Tissierella were increased. The decrease of Prevotella was rapid in broilers but delayed in calves and piglets. Knowing when these pathobionts increase in abundance after aerobic exposure could inform farm sanitation practices and could be important in designing animal experiments that modulate the microbiome.IMPORTANCEThe fecal microbial community is contained within a dynamic ecosystem of interacting microbes that varies in biotic and abiotic components across different animal species. Although oxygen affects bacterial growth, its specific impact on the structure of complex communities, such as those found in feces, and how these effects vary between different animal species are poorly understood. In this study, we demonstrate that the effect of aerobic exposure on the fecal microbiota was host-animal-specific, primarily driven by a decrease in Firmicutes and Bacteroidetes, but accompanied by an increase in Actinobacteria, Proteobacteria, and other pathobionts. Interestingly, we observed that more complex communities from pig and cattle exhibited initial resilience, while a less diverse community from broilers displayed a rapid response to aerobic exposure. Our findings offer insights that can inform farm sanitation practices, as well as experimental design, sample collection, and processing protocols for microbiome studies across various animal species.

Intraoperative hemodynamics and risk of cardiac surgery-associated acute kidney injury: An observation study and a feasibility clinical trial.

Targeting greater pump flow and mean arterial pressure (MAP) during cardiopulmonary bypass (CPB) could potentially alleviate renal hypoxia and reduce the risk of postoperative acute kidney injury (AKI). Therefore, in an observational study of 93 patients undergoing on-pump cardiac surgery, we tested whether intraoperative hemodynamic management differed between patients who did and did not develop AKI. Then, in 20 patients, we assessed the feasibility of a larger-scale trial in which patients would be randomized to greater than normal target pump flow and MAP, or usual care, during CPB. In the observational cohort, MAP during hypothermic CPB averaged 68.8 ± 8.0 mmHg (mean ± SD) in the 36 patients who developed AKI and 68.9 ± 6.3 mmHg in the 57 patients who did not (p = 0.98). Pump flow averaged 2.4 ± 0.2 L/min/m2 in both groups. In the feasibility clinical trial, compared with usual care, those randomized to increased target pump flow and MAP had greater mean pump flow (2.70 ± 0.23 vs. 2.42 ± 0.09 L/min/m2 during the period before rewarming) and systemic oxygen delivery (363 ± 60 vs. 281 ± 45 mL/min/m2 ). Target MAP ≥80 mmHg was achieved in 66.6% of patients in the intervention group but in only 27.3% of patients in the usual care group. Nevertheless, MAP during CPB did not differ significantly between the two groups. We conclude that little insight was gained from our observational study regarding the impact of variations in pump flow and MAP on the risk of AKI. However, a clinical trial to assess the effects of greater target pump flow and MAP on the risk of AKI appears feasible.

Hepatitis C: A Rare Cause of Subacute Paralysis.

The effects of the hepatitis C virus (HCV) on the nervous system have been primarily reported with a pathology of the peripheral nervous system through the involvement of a vasculitic process via cryoglobulinemia. A review of the recent literature reinforced the likely association between chronic HCV infection and transverse myelitis (TM), but the causal relationship remains elusive. Here, we present a rare case of acute TM developing over the course of days from symptom onset and a concomitant new diagnosis of HCV infection. A 31-year-old male with a medical history of stimulant use disorder with intravenous methamphetamine use presented to the hospital for acute bilateral leg weakness. The weakness was predominantly in his thighs and later progressed to his calves over the course of days. He denied urinary or fecal incontinence; however, on hospital day two, he developed acute urinary retention requiring the insertion of a Foley catheter. An initial MRI of the spine revealed an intramedullary T2 hyperintense signal at the lower thoracic cord concerning for TM, multiple sclerosis, ischemia, or neoplasm. MRI of the brain was unremarkable. Lumbar puncture results also displayed no abnormalities. HCV screening should be considered in all patients who develop acute neurological deficits that are not otherwise explained, such as TM, given the significant morbidity associated with delayed treatment.

Mitochondrial morphology controls fatty acid utilization by changing CPT1 sensitivity to malonyl-CoA.

Changes in mitochondrial morphology are associated with nutrient utilization, but the precise causalities and the underlying mechanisms remain unknown. Here, using cellular models representing a wide variety of mitochondrial shapes, we show a strong linear correlation between mitochondrial fragmentation and increased fatty acid oxidation (FAO) rates. Forced mitochondrial elongation following MFN2 over-expression or DRP1 depletion diminishes FAO, while forced fragmentation upon knockdown or knockout of MFN2 augments FAO as evident from respirometry and metabolic tracing. Remarkably, the genetic induction of fragmentation phenocopies distinct cell type-specific biological functions of enhanced FAO. These include stimulation of gluconeogenesis in hepatocytes, induction of insulin secretion in islet ß-cells exposed to fatty acids, and survival of FAO-dependent lymphoma subtypes. We find that fragmentation increases long-chain but not short-chain FAO, identifying carnitine O-palmitoyltransferase 1 (CPT1) as the downstream effector of mitochondrial morphology in regulation of FAO. Mechanistically, we determined that fragmentation reduces malonyl-CoA inhibition of CPT1, while elongation increases CPT1 sensitivity to malonyl-CoA inhibition. Overall, these findings underscore a physiologic role for fragmentation as a mechanism whereby cellular fuel preference and FAO capacity are determined.

Association Between Changes in Norepinephrine Infusion Rate and Urinary Oxygen Tension After Cardiac Surgery.

OBJECTIVES: To determine if the administration of norepinephrine to patients recovering from on-pump cardiac surgery is associated with changes in urinary oxygen tension (PO2), an indirect index of renal medullary oxygenation. DESIGN: Single center, prospective observational study. SETTING: Surgical intensive care unit (ICU). PARTICIPANTS: A nonconsecutive sample of 93 patients recovering from on-pump cardiac surgery. MEASUREMENTS AND MAIN RESULTS: In the ICU, norepinephrine was the most commonly used vasopressor agent (90% of patients, 84/93), with fewer patients receiving epinephrine (48%, 45/93) or vasopressin (4%, 4/93). During the 30-to-60-minute period after increasing the infused dose of norepinephrine (n = 89 instances), urinary PO2 decreased by (least squares mean ± SEM) 1.8 ± 0.5 mmHg from its baseline level of 25.1 ± 1.1 mmHg. Conversely, during the 30-to-60-minute period after the dose of norepinephrine was decreased (n = 134 instances), urinary PO2 increased by 2.6 ± 0.5 mmHg from its baseline level of 22.7 ± 1.2 mmHg. No significant change in urinary PO2 was detected when the dose of epinephrine was decreased (n = 21). There were insufficient observations to assess the effects of increasing the dose of epinephrine (n = 11) or of changing the dose of vasopressin (n <4). CONCLUSIONS: In patients recovering from on-pump cardiac surgery, changes in norepinephrine dose are associated with reciprocal changes in urinary PO2, potentially reflecting an effect of norepinephrine on renal medullary oxygenation.

A rare case of Acrodermatitis continua of Hallopeau successfully treated with topical calcipotriol/betamethasone dipropionate ointment associated with Jaccaud's arthropathy: A case report.

Acrodermatitis continua of Hallopeau (ACH) is a rare and localized form of pustular psoriasis that can lead to irreversible anonychia whereas Jaccoud's arthropathy (JA) is a rare non-articular condition characterized by a deforming non-erosive arthropathy involving the digits. This case describes the first reported association of these two rare conditions in a 73-year-old Filipino male who was treated topically until remission of ACH. Because calcipotriol/betamethasone ointment works better and faster than clobetasol ointment, it may be considered as a preferred first-line treatment for ACH. This case also highlights the evaluation of joint symptoms in the context of psoriatic arthritis and JA, along with a discussion of its management. A multidisciplinary approach involving dermatology, rheumatology, and physiatry is essential in the care of these two rare conditions.

Review of the utility of routine mortality reviews among deaths on General Internal Medicine wards in a Canadian tertiary care hospital.

BACKGROUND: Hospital morbidity and mortality reviews are common quality assurance activities, intended to uncover latent or unrecognised systemic issues that contribute to preventable adverse events and patient harm. Mortality reviews may be routinely mandated by hospital policy or for accreditation purposes. However, patients under the care of certain specialties, such as general internal medicine (GIM), are affected by a substantial burden of chronic disease, advanced age, frailty or limited life expectancy. Many of their deaths could be viewed as reasonably foreseeable, and unrelated to poor-quality care. METHODS: We sought to determine how frequently postmortem chart reviews for hospitalised GIM patients at our tertiary care centre in Canada would uncover patient safety or quality of care issues that directly led to these patients' deaths. We reviewed the charts of all patients who died while admitted to the GIM admitting service over a 12-month time period between 1 July 2020 and 30 June 2021. RESULTS: We found that in only 2% of cases was a clinical adverse event detected that directly contributed to a poor or unexpected outcome for the patient, and of those cases, more than half were related to unfortunate nosocomial transmission of COVID-19 infection. CONCLUSION: Due to an overall low yield, we discourage routine mortality chart reviews for general medical patients, and instead suggest that organisations focus on strategies to recognise and capture safety incidents that may not necessarily result in death.

Parkin regulates adiposity by coordinating mitophagy with mitochondrial biogenesis in white adipocytes.

Parkin, an E3 ubiquitin ligase, plays an essential role in mitochondrial quality control. However, the mechanisms by which Parkin connects mitochondrial homeostasis with cellular metabolism in adipose tissue remain unclear. Here, we demonstrate that Park2 gene (encodes Parkin) deletion specifically from adipose tissue protects mice against high-fat diet and aging-induced obesity. Despite a mild reduction in mitophagy, mitochondrial DNA content and mitochondrial function are increased in Park2 deficient white adipocytes. Moreover, Park2 gene deletion elevates mitochondrial biogenesis by increasing Pgc1α protein stability through mitochondrial superoxide-activated NAD(P)H quinone dehydrogenase 1 (Nqo1). Both in vitro and in vivo studies show that Nqo1 overexpression elevates Pgc1α protein level and mitochondrial DNA content and enhances mitochondrial activity in mouse and human adipocytes. Taken together, our findings indicate that Parkin regulates mitochondrial homeostasis by balancing mitophagy and Pgc1α-mediated mitochondrial biogenesis in white adipocytes, suggesting a potential therapeutic target in adipocytes to combat obesity and obesity-associated disorders.

Improving incident reporting among physicians at south health campus hospital.

Reports of adverse events and near-misses provide the opportunity to learn about latent (systems) errors. However, voluntary incident reporting systems are underused by physicians. While reports submitted by nursing staff relate to common hazards such as medication administration or falls, physicians have broader exposure to patients' entire hospital journey. Reports by physicians have the potential to uncover more serious errors that could span multiple departments and layers of personnel. Organisational safety culture thrives when all staff are represented and feel empowered to share safety concerns.At the South Health Campus (SHC) Hospital in Calgary, Alberta, Canada, the baseline proportion of physician-submitted reports within our site's Reporting and Learning System (RLS) from July 2013 to December 2016 was 1.12%. We implemented an intervention to double the proportion of physician-submitted RLS reports, using quality improvement methods.Focus groups identified lack of experience with the RLS system, lack of feedback or closure after an RLS submission, and apprehensions about disclosing the incident to the affected patient as barriers to physician submission. Accordingly, the intervention involved direct responses from physician leadership to each physician-submitted RLS report, multimedia demonstrations of efficient RLS submission to physician groups and medical learners, and linkage to materials on safe disclosures. Effectiveness was assessed using a controlled before-and-after design, comparing SHC with the rest of Calgary and with the rest of Alberta.Following the intervention, the proportion of RLS reports that were physician submitted increased to 2.65% (OR 2.42 [95% CI 1.96 to 3.02], p<0.001), sustained over the following 4 years. While an increase was observed for the rest of Calgary, it was smaller (OR 1.27 [1.15 to 1.40], p<0.001). A decrease in the odds of physician submission was observed for the rest of Alberta. Differences between sites were significant (p<0.001).Overall, we found that physician-submitted incident reports can be increased and sustained over time if submitters receive personalised feedback by a physician safety leader. At our site, reports submitted by physicians have been valuable in uncovering complex systems issues that may not have been readily apparent.

Bilioptysis associated with alcohol hepatitis without evidence of bronchobiliary fistula: A rare case report.

The presence of bilirubin in the sputum is uncommon but, when present, is most commonly associated with the presence of bronchobiliary fistula, which could be associated with a number of underlying conditions. However, the finding of bilioptysis without bronchobiliary fistula is uncommon, with one associated mechanism postulated to involve increased capillary membrane permeability. This case report describes a patient presenting with bilioptysis while being medically managed with prednisolone for severe alcoholic hepatitis. The patient developed hospital-acquired pneumonia during her hospitalization associated with bilioptysis, resulting in progressive respiratory failure requiring ventilatory support. Alcohol-related pulmonary dysfunction alters pulmonary immune processes, leading to increased susceptibility to pulmonary infection and disrupting the basal alveolar epithelial membrane, thus increasing permeability. This patient's findings were in the absence of a bronchobiliary or bronchopleural fistula, and we hypothesize that increased capillary membrane permeability was contributory to the bilioptysis in this case.

The mitochondrial fission protein Drp1 in liver is required to mitigate NASH and prevents the activation of the mitochondrial ISR.

OBJECTIVE: The mitochondrial fission protein Drp1 was proposed to promote NAFLD, as inhibition of hepatocyte Drp1 early in life prevents liver steatosis induced by high-fat diet in mice. However, whether Drp1-knockdown in older mice can reverse established NASH is unknown. METHODS: N-acetylgalactosamine-siRNA conjugates, an FDA approved method to deliver siRNA selectively to hepatocytes, were used to knockdown hepatocyte-Drp1 in mice (NAG-Drp1si). NASH was induced in C57BL/6NTac mice by Gubra-Amylin-NASH diet (D09100310, 40% fat, 22% fructose and 2% cholesterol) and treatment with NAG-Drp1si was started at week 24 of diet. Circulating transaminases, liver histology, gene expression of fibrosis and inflammation markers, and hydroxyproline synthesis determined NASH severity. Liver NEFA and triglycerides were quantified by GC/MS. Mitochondrial function was determined by respirometry. Western blots of Oma1, Opa1, p-eIf2α, as well as transcriptional analyses of Atf4-regulated genes determined ISR engagement. RESULTS: NAG-Drp1si treatment decreased body weight and induced liver inflammation in adult healthy mice. Increased hepatic Gdf15 production was the major contributor to body-weight loss caused by NAG-Drp1si treatment, as Gdf15 receptor deletion (Gfral KO) prevented the decrease in food intake and mitigated weight loss. NAG-Drp1si activated the Atf4-controlled integrated stress response (ISR) to increase hepatic Gdf15 expression. NAG-Drp1si in healthy mice caused ER stress and activated the mitochondrial protease Oma1, which are the ER and mitochondrial triggers that activate the Atf4-controlled ISR. Remarkably, induction of NASH was not sufficient to activate Oma1 in liver. However, NAG-Drp1si treatment was sufficient to activate Oma1 in adult mice with NASH, as well as exacerbating NASH-induced ER stress. Consequently, NAG-Drp1si treatment in mice with NASH led to higher ISR activation, exacerbated inflammation, fibrosis and necrosis. CONCLUSION: Drp1 mitigates NASH by decreasing ER stress, preventing Oma1 activation and ISR exacerbation. The elevation in Gdf15 actions induced by NAG-Drp1si might represent an adaptive response decreasing the nutrient load to liver when mitochondria are misfunctional. Our study argues against blocking Drp1 in hepatocytes to combat NASH.

Dynamic responses of renal oxygenation at the onset of cardiopulmonary bypass in sheep and man.

INTRODUCTION: The renal medulla is susceptible to hypoxia during cardiopulmonary bypass (CPB), which may contribute to the development of acute kidney injury. But the speed of onset of renal medullary hypoxia remains unknown. METHODS: We continuously measured renal medullary oxygen tension (MPO2) in 24 sheep, and urinary PO2 (UPO2) as an index of MPO2 in 92 patients, before and after induction of CPB. RESULTS: In laterally recumbent sheep with a right thoracotomy (n = 20), even before CPB commenced MPO2 fell from (mean ± SEM) 52 ± 4 to 41 ±5 mmHg simultaneously with reduced arterial pressure (from 108 ± 5 to 88 ± 5 mmHg). In dorsally recumbent sheep with a medial sternotomy (n = 4), MPO2 was even more severely reduced (to 12 ± 12 mmHg) before CPB. In laterally recumbent sheep in which a crystalloid prime was used (n = 7), after commencing CPB, MPO2 fell abruptly to 24 ±6 mmHg within 20-30 minutes. MPO2 during CPB was not improved by adding donor blood to the prime (n = 13). In patients undergoing cardiac surgery, UPO2 fell by 4 ± 1 mmHg and mean arterial pressure fell by 7 ± 1 mmHg during the 30 minutes before CPB. UPO2 then fell by a further 12 ± 2 mmHg during the first 30 minutes of CPB but remained relatively stable for the remaining 24 minutes of observation. CONCLUSIONS: Renal medullary hypoxia is an early event during CPB. It starts to develop even before CPB, presumably due to a pressure-dependent decrease in renal blood flow. Medullary hypoxia during CPB appears to be promoted by hypotension and is not ameliorated by increasing blood hemoglobin concentration.

Intra-operative and early post-operative prediction of cardiac surgery-associated acute kidney injury: Urinary oxygen tension compared with plasma and urinary biomarkers.

Acute kidney injury (AKI) is a common and serious post-operative complication of cardiac surgery. The value of a predictive biomarker is determined not only by its predictive efficacy, but also by how early this prediction can be made. For a biomarker of cardiac surgery-associated AKI, this is ideally during the intra-operative period. Therefore, in 82 adult patients undergoing cardiac surgery requiring cardiopulmonary bypass (CPB), we prospectively compared the predictive efficacy of various blood and urinary biomarkers with that of continuous measurement of urinary oxygen tension (UPO2 ) at pre-determined intra- and post-operative time-points. None of the blood or urine biomarkers we studied showed predictive efficacy for post-operative AKI when measured intra-operatively. When treated as a binary variable (≤ or > median for the whole cohort), the earliest excess risk of AKI was predicted by an increase in urinary neutrophil gelatinase-associated lipocalin (NGAL) at 3 h after entry into the intensive care unit (odds ratio [95% confidence limits], 2.86 [1.14-7.21], p = 0.03). Corresponding time-points were 6 h for serum creatinine (3.59 [1.40-9.20], p = 0.008), and 24 h for plasma NGAL (4.54 [1.73-11.90], p = 0.002) and serum cystatin C (6.38 [2.35-17.27], p = 0.001). In contrast, indices of intra-operative urinary hypoxia predicted AKI after weaning from CPB, and in the case of a fall in UPO2 to ≤10 mmHg, during the rewarming phase of CPB (3.00 [1.19-7.56], p = 0.02). We conclude that continuous measurement of UPO2 predicts AKI earlier than plasma or urinary NGAL, serum cystatin C, or early post-operative changes in serum creatinine.

Mitochondrial Heterogeneity in Metabolic Diseases.

Mitochondria have distinct architectural features and biochemical functions consistent with cell-specific bioenergetic needs. However, as imaging and isolation techniques advance, heterogeneity amongst mitochondria has been observed to occur within the same cell. Moreover, mitochondrial heterogeneity is associated with functional differences in metabolic signaling, fuel utilization, and triglyceride synthesis. These phenotypic associations suggest that mitochondrial subpopulations and heterogeneity influence the risk of metabolic diseases. This review examines the current literature regarding mitochondrial heterogeneity in the pancreatic beta-cell and renal proximal tubules as they exist in the pathological and physiological states; specifically, pathological states of glucolipotoxicity, progression of type 2 diabetes, and kidney diseases. Emphasis will be placed on the benefits of balancing mitochondrial heterogeneity and how the disruption of balancing heterogeneity leads to impaired tissue function and disease onset.

Intraoperative renal hypoxia and risk of cardiac surgery-associated acute kidney injury.

BACKGROUND: Acute kidney injury (AKI) is common after cardiac surgery requiring cardiopulmonary bypass. Renal hypoxia may precede clinically detectable AKI. We compared the efficacy of two indices of renal hypoxia, (i) intraoperative urinary oxygen tension (UPO2 ) and (ii) the change in plasma erythropoietin (pEPO) during surgery, in predicting AKI. We also investigated whether the performance of these prognostic markers varies with preoperative patient characteristics. METHODS: In 82 patients undergoing on-pump cardiac surgery, blood samples were taken upon induction of anesthesia and upon entry into the intensive care unit. UPO2 was continuously measured throughout surgery. RESULTS: Thirty-two (39%) patients developed postoperative AKI. pEPO increased during surgery, but this increase did not predict AKI, regardless of risk of postoperative mortality assessed by EuroSCORE-II. For patients categorized at higher risk by EuroSCORE-II >1.98 (median score for the cohort), UPO2 ≤10 mmHg at any time during surgery predicted a 4.04-fold excess risk of AKI (p = .04). However, UPO2 did not significantly predict AKI in lower-risk patients. UPO2 significantly predicted AKI in patients who were older, had previous myocardial infarction, diabetes, lower preoperative serum creatinine, or shorter bypass times. pEPO and UPO2 were only weakly correlated. CONCLUSIONS: Intraoperative change in pEPO does not predict AKI. However, UPO2 shows promise, particularly in patients with higher risk of operative mortality. The disparity between these two markers of renal hypoxia may indicate that UPO2 reflects medullary oxygenation whereas pEPO reflects cortical oxygenation.

ABCB10 exports mitochondrial biliverdin, driving metabolic maladaptation in obesity.

Although the role of hydrophilic antioxidants in the development of hepatic insulin resistance and nonalcoholic fatty liver disease has been well studied, the role of lipophilic antioxidants remains poorly characterized. A known lipophilic hydrogen peroxide scavenger is bilirubin, which can be oxidized to biliverdin and then reduced back to bilirubin by cytosolic biliverdin reductase. Oxidation of bilirubin to biliverdin inside mitochondria must be followed by the export of biliverdin to the cytosol, where biliverdin is reduced back to bilirubin. Thus, the putative mitochondrial exporter of biliverdin is expected to be a major determinant of bilirubin regeneration and intracellular hydrogen peroxide scavenging. Here, we identified ABCB10 as a mitochondrial biliverdin exporter. ABCB10 reconstituted into liposomes transported biliverdin, and ABCB10 deletion caused accumulation of biliverdin inside mitochondria. Obesity with insulin resistance up-regulated hepatic ABCB10 expression in mice and elevated cytosolic and mitochondrial bilirubin content in an ABCB10-dependent manner. Revealing a maladaptive role of ABCB10-driven bilirubin synthesis, hepatic ABCB10 deletion protected diet-induced obese mice from steatosis and hyperglycemia, improving insulin-mediated suppression of glucose production and decreasing lipogenic SREBP-1c expression. Protection was concurrent with enhanced mitochondrial function and increased inactivation of PTP1B, a phosphatase disrupting insulin signaling and elevating SREBP-1c expression. Restoration of cellular bilirubin content in ABCB10 KO hepatocytes reversed the improvements in mitochondrial function and PTP1B inactivation, demonstrating that bilirubin was the maladaptive effector linked to ABCB10 function. Thus, we identified a fundamental transport process that amplifies intracellular bilirubin redox actions, which can exacerbate insulin resistance and steatosis in obesity.

Isolation and functional analysis of peridroplet mitochondria from murine brown adipose tissue.

Mitochondria play a central role in lipid metabolism and can bind to lipid droplets. However, the role and functional specialization of the population of peridroplet mitochondria (PDMs) remain unclear, as methods to isolate functional PDMs were not developed until recently. Here, we describe an approach to isolate intact PDMs from murine brown adipose tissue based on their adherence to lipid droplets. PDMs isolated using our approach can be used to study their specialized function by respirometry. For complete information on the use and execution of this protocol, please refer to Benador et al. (2018).

ß-blockade prevents coronary macro- and microvascular dysfunction induced by a high salt diet and insulin resistance in the Goto-Kakizaki rat.

A high salt intake exacerbates insulin resistance, evoking hypertension due to systemic perivascular inflammation, oxidative-nitrosative stress and endothelial dysfunction. Angiotensin-converting enzyme inhibitor (ACEi) and angiotensin receptor blockers (ARBs) have been shown to abolish inflammation and redox stress but only partially restore endothelial function in mesenteric vessels. We investigated whether sympatho-adrenal overactivation evokes coronary vascular dysfunction when a high salt intake is combined with insulin resistance in male Goto-Kakizaki (GK) and Wistar rats treated with two different classes of ß-blocker or vehicle, utilising synchrotron-based microangiography in vivo. Further, we examined if chronic carvedilol (CAR) treatment preserves nitric oxide (NO)-mediated coronary dilation more than metoprolol (MET). A high salt diet (6% NaCl w/w) exacerbated coronary microvessel endothelial dysfunction and NO-resistance in vehicle-treated GK rats while Wistar rats showed modest impairment. Microvascular dysfunction was associated with elevated expression of myocardial endothelin, inducible NO synthase (NOS) protein and 3-nitrotyrosine (3-NT). Both CAR and MET reduced basal coronary perfusion but restored microvessel endothelium-dependent and -independent dilation indicating a role for sympatho-adrenal overactivation in vehicle-treated rats. While MET treatment reduced myocardial nitrates, only MET treatment completely restored microvessel dilation to dobutamine (DOB) stimulation in the absence of NO and prostanoids (combined inhibition), indicating that MET restored the coronary flow reserve attributable to endothelium-derived hyperpolarisation (EDH). In conclusion, sympatho-adrenal overactivation caused by high salt intake and insulin resistance evoked coronary microvessel endothelial dysfunction and diminished NO sensitivity, which were restored by MET and CAR treatment in spite of ongoing inflammation and oxidative-nitrosative stress presumably caused by uninhibited renin-angiotensin-aldosterone system (RAAS) overactivation.

Mitochondrial oxidative function in NAFLD: Friend or foe?

BACKGROUND: Mitochondrial oxidative function plays a key role in the development of non-alcoholic fatty liver disease (NAFLD) and insulin resistance (IR). Recent studies reported that fatty liver might not be a result of decreased mitochondrial fat oxidation caused by mitochondrial damage. Rather, NAFLD and IR induce an elevation in mitochondrial function that covers the increased demand for carbon intermediates and ATP caused by elevated lipogenesis and gluconeogenesis. Furthermore, mitochondria play a role in regulating hepatic insulin sensitivity and lipogenesis by modulating redox-sensitive signaling pathways. SCOPE OF REVIEW: We review the contradictory studies indicating that NAFLD and hyperglycemia can either increase or decrease mitochondrial oxidative capacity in the liver. We summarize mechanisms regulating mitochondrial heterogeneity inside the same cell and discuss how these mechanisms may determine the role of mitochondria in NAFLD. We further discuss the role of endogenous antioxidants in controlling mitochondrial H2O2 release and redox-mediated signaling. We describe the emerging concept that the subcellular location of cellular antioxidants is a key determinant of their effects on NAFLD. MAJOR CONCLUSIONS: The balance of fat oxidation versus accumulation depends on mitochondrial fuel preference rather than ATP-synthesizing respiration. As such, therapies targeting fuel preference might be more suitable for treating NAFLD. Similarly, suppressing maladaptive antioxidants, rather than interfering with physiological mitochondrial H2O2-mediated signaling, may allow the maintenance of intact hepatic insulin signaling in NAFLD. Exploration of the subcellular compartmentalization of different antioxidant systems and the unique functions of specific mitochondrial subpopulations may offer new intervention points to treat NAFLD.