Subcellular Energetics and Metabolism: Potential Therapeutic Applications

Impact of functional status on 30-day resource utilization and organ system complications following index bariatric surgery: a cohort study

BACKGROUND

Bariatric surgical procedures carry an appreciable risk profile despite their elective nature. Identified risk factors for procedural complications are often limited to medical comorbidities. This study assesses the impact of functional status on resource utilization and organ system complications following bariatric surgery.

MATERIALS AND METHODS

This retrospective cohort study analyzed patients undergoing elective, index bariatric surgery from American College of Surgeons National Surgical Quality Improvement Program participating hospitals from 2015 to 2019 ( n =65 627). The primary independent variable was functional status. The primary outcome was unplanned resource utilization. Secondary outcomes included composite organ system complications and mortality. The impact of functional status was first investigated with univariate analyses. Survival and multivariate analyses were then performed on select complications with clinically and statistically significant incidence in the dependent cohort.

RESULTS

On univariate analysis, dependent functional status was associated with unplanned resource utilization [12.1% (27/223) vs. 4.1% (2661/65 404)]; relative risk, 2.98 (95% CI, 2.09-4.25); P < 0.001] and haematologic/infectious complications [6.7% (15/223) vs. 2.4% (1540/65 404); relative risk, 2.86 (95% CI, 1.75-4.67); P < 0.001]. Survival analysis demonstrated a significantly shorter time to both events in patients with dependent functional status ( P < 0.001). On multivariate analysis, dependent functional status was an independent predictor of unplanned resource utilization[adjusted odds ratio 2.17 (95% CI, 1.27-3.50); P = 0.003; model c-statistic, 0.572]) and haematologic/infectious complications [adjusted odds ratio, 2.20 ([95% CI, 1.14-3.86); P = 0.011; model c-statistic, 0.579].

CONCLUSION

Patients with dependent functional status are at an elevated risk of unplanned resource utilization and haematologic/infectious complications following index bariatric surgery. The increased risk cannot be explained by medical comorbidities alone.

Oxygen in Metabolic Dysfunction and Its Therapeutic Relevance

Significance: In recent years, a number of studies have shown altered oxygen partial pressure at a tissue level in metabolic disorders, and some researchers have considered oxygen to be a (macro) nutrient. Oxygen availability may be compromised in obesity and several other metabolism-related pathological conditions, including sleep apnea-hypopnea syndrome, the metabolic syndrome (which is a set of conditions), type 2 diabetes, cardiovascular disease, and cancer. Recent Advances: Strategies designed to reduce adiposity and its accompanying disorders have been mainly centered on nutritional interventions and physical activity programs. However, novel therapies are needed since these approaches have not been sufficient to counteract the worldwide increasing rates of metabolic disorders. In this regard, intermittent hypoxia training and hyperoxia could be potential treatments through oxygen-related adaptations. Moreover, living at a high altitude may have a protective effect against the development of abnormal metabolic conditions. In addition, oxygen delivery systems may be of therapeutic value for supplying the tissue-specific oxygen requirements. Critical Issues: Precise in vivo methods to measure oxygenation are vital to disentangle some of the controversies related to this research area. Further, it is evident that there is a growing need for novel in vitro models to study the potential pathways involved in metabolic dysfunction to find appropriate therapeutic targets. Future Directions: Based on the existing evidence, it is suggested that oxygen availability has a key role in obesity and its related comorbidities. Oxygen should be considered in relation to potential therapeutic strategies in the treatment and prevention of metabolic disorders. Antioxid. Redox Signal. 35, 642-687.

Impact of inflammation on brain subcellular energetics in anesthetized rats

Background

Emerging data suggests that volatile anesthetic agents may have organ protection properties in the setting of critical illness. The purpose of this study was to better understand the effect of inflammation on cerebral subcellular energetics in animals exposed to two different anesthetic agents—a GABA agonist (propofol) and a volatile agent (isoflurane).

Results

Forty-eight Sprague–Dawley rats were anesthetized with isoflurane or propofol. In each group, rats were randomized to celiotomy and closure (sham) or cecal ligation and puncture (inflammation [sepsis model]) for 8 h. Brain tissue oxygen saturation and the oxidation state of cytochrome aa₃ were measured. Brain tissue was extracted using the freeze-blow technique. All rats experienced progressive increases in tissue oxygenation and cytochrome aa₃ reduction over time. Inflammation had no impact on cytochrome aa₃, but isoflurane caused significant cytochrome aa₃ reduction. During isoflurane (not propofol) anesthesia, inflammation led to an increase in lactate (+ 0.64 vs. − 0.80 mEq/L, p = 0.0061). There were no differences in ADP:ATP ratios between groups. In the isoflurane (not propofol) group, inflammation increased the expression of hypoxia-inducible factor-1α (62%, p = 0.0012), heme oxygenase-1 (67%, p = 0.0011), and inducible nitric oxide synthase (31%, p = 0.023) in the brain. Animals exposed to inflammation and isoflurane (but not propofol) exhibited increased expression of protein carbonyls (9.2 vs. 7.0 nM/mg protein, p = 0.0050) and S-nitrosylation (49%, p = 0.045) in the brain. RNA sequencing identified an increase in heat shock protein 90 and NF-κβ inhibitor mRNA in the inflammation/isoflurane group.

Conclusions

In the setting of inflammation, rats exposed to isoflurane show increased hypoxia-inducible factor-1α expression despite a lack of hypoxia, increased oxidative stress in the brain, and increased serum lactate, all of which suggest a relative increase in anaerobic metabolism compared to propofol. Differences in oxidative stress as well as heat shock protein 90 and NF-κβ inhibitor may account for the differential expression of cerebral hypoxia-inducible factor-1α during inflammation.

Electronic supplementary material

The online version of this article (10.1186/s12868-019-0514-8) contains supplementary material, which is available to authorized users.

New advances in perioperative cardioprotection

With the increasing age of the general population, medical conditions necessitating a surgical intervention will increase. Concomitant with advanced age, the prevalence of type 2 diabetes mellitus will also increase. These patients have a two- to three-fold higher risk of occurrence of cardiovascular events and are at higher risk of perioperative myocardial ischemia. This review will discuss recent advances in the field of perioperative cardioprotection and focus specifically on strategies that have aimed to protect the diabetic and the aged myocardium. This review will not deal with potential putative cardioprotective effects of opioids and anesthetic agents, as this is a very broad area that would necessitate a dedicated overview.