The endoplasmic reticulum kinase PERK interacts with the oxidoreductase ERO1 to metabolically adapt mitochondria

Endoplasmic reticulum (ER) homeostasis requires molecular regulators that tailor mitochondrial bioenergetics to the needs of protein folding. For instance, calnexin maintains mitochondria metabolism and mitochondria-ER contacts (MERCs) through reactive oxygen species (ROS) from NADPH oxidase 4 (NOX4). However, induction of ER stress requires a quick molecular rewiring of mitochondria to adapt to new energy needs. This machinery is not characterized. We now show that the oxidoreductase ERO1⍺ covalently interacts with protein kinase RNA-like ER kinase (PERK) upon treatment with tunicamycin. The PERK-ERO1⍺ interaction requires the C-terminal active site of ERO1⍺ and cysteine 216 of PERK. Moreover, we show that the PERK-ERO1⍺ complex promotes oxidization of MERC proteins and controls mitochondrial dynamics. Using proteinaceous probes, we determined that these functions improve ER-mitochondria Ca²⁺ flux to maintain bioenergetics in both organelles, while limiting oxidative stress. Therefore, the PERK-ERO1⍺ complex is a key molecular machinery that allows quick metabolic adaptation to ER stress.

Endoplasmic reticulum chaperones tweak the mitochondrial calcium rheostat to control metabolism and cell death

The folding of secretory proteins is a well-understood mechanism, based on decades of research on endoplasmic reticulum (ER) chaperones. These chaperones interact with newly imported polypeptides close to the ER translocon. Classic examples for these proteins include the immunoglobulin binding protein (BiP/GRP78), and the lectins calnexin and calreticulin. Although not considered chaperones per se, the ER oxidoreductases of the protein disulfide isomerase (PDI) family complete the folding job by catalyzing the formation of disulfide bonds through cysteine oxidation. Research from the past decade has demonstrated that ER chaperones are multifunctional proteins. The regulation of ER-mitochondria Ca²⁺ crosstalk is one of their additional functions, as shown for calnexin, BiP/GRP78 or the oxidoreductases Ero1α and TMX1. This function depends on interactions of this group of proteins with the ER Ca²⁺ handling machinery. This novel function makes perfect sense for two reasons: i. It allows ER chaperones to control mitochondrial apoptosis instantly without a lengthy bypass involving the upregulation of pro-apoptotic transcription factors via the unfolded protein response (UPR); and ii. It allows the ER protein folding machinery to fine-tune ATP import via controlling the speed of mitochondrial oxidative phosphorylation. Therefore, the role of ER chaperones in regulating ER-mitochondria Ca²⁺ flux identifies the progression of secretory protein folding as a central regulator of cell survival and death, at least in cell types that secrete large amount of proteins. In other cell types, ER protein folding might serve as a sentinel mechanism that monitors cellular well-being to control cell metabolism and apoptosis. The selenoprotein SEPN1 is a classic example for such a role. Through the control of ER-mitochondria Ca²⁺-flux, ER chaperones and folding assistants guide cellular apoptosis and mitochondrial metabolism.

Noninvasive Mechanical Ventilation in Acute Respiratory Failure Patients: A Respiratory Therapist Perspective

Physiotherapist in Chile and Respiratory Therapist worldwide are the professionals who are experts in respiratory care, in mechanical ventilation (MV), pathophysiology and connection and disconnection criteria. They should be experts in every aspect of the acute respiratory failure and its management, they and are the ones who in medical units are able to resolve doubts about ventilation and the setting of the ventilator. Noninvasive mechanical ventilation should be the first-line of treatment in acute respiratory failure, and the standard of care in severe exacerbations of chronic obstructive pulmonary disease, acute cardiogenic pulmonary edema, and in immunosuppressed patients with high levels of evidence that support the work of physiotherapist. Exist other considerations where most of the time, physicians and other professionals in the critical units do not take into account when checking the patient ventilator synchrony, such as the appropriate patient selection, ventilator selection, mask selection, mode selection, and the selection of a trained team in NIMV. The physiotherapist needs to evaluate bedside; if patients are properly connected to the ventilator and in a synchronously manner. In Chile, since 2004, the physioterapist are included in the guidelines as a professional resource in the ICU organization, with the same skills and obligations as those described in the literature for respiratory therapists.

Pathophysiological Basis of Acute Respiratory Failure on Non-Invasive Mechanical Ventilation

Noninvasive mechanical ventilation (NIMV) was created for patients who needed noninvasive ventilator support, this procedure decreases the complications associated with the use of endotracheal intubation (ETT). The application of NIMV has acquired major relevance in the last few years in the management of acute respiratory failure (ARF), in patients with hypoxemic and hypercapnic failure. The main advantage of NIMV as compared to invasive mechanical ventilation (IMV) is that it can be used earlier outside intensive care units (ICUs). The evidence strongly supports its use in patients with COPD exacerbation, support in weaning process in chronic obstructive pulmonary disease (COPD) patients, patients with acute cardiogenic pulmonary edema (ACPE), and Immunosuppressed patients. On the other hand, there is poor evidence that supports the use of NIMV in other pathologies such as pneumonia, acute respiratory distress syndrome (ARDS), and during procedures as bronchoscopy, where its use is still controversial because the results of these studies are inconclusive against the decrease in the rate of intubation or mortality.

Humidification on Ventilated Patients: Heated Humidifications or Heat and Moisture Exchangers?

The normal physiology of conditioning of inspired gases is altered when the patient requires an artificial airway access and an invasive mechanical ventilation (IMV). The endotracheal tube (ETT) removes the natural mechanisms of filtration, humidification and warming of inspired air. Despite the noninvasive ventilation (NIMV) in the upper airways, humidification of inspired gas may not be optimal mainly due to the high flow that is being created by the leakage compensation, among other aspects. Any moisture and heating deficit is compensated by the large airways of the tracheobronchial tree, these are poorly suited for this task, which alters mucociliary function, quality of secretions, and homeostasis gas exchange system. To avoid the occurrence of these events, external devices that provide humidification, heating and filtration have been developed, with different degrees of evidence that support their use.

Glycoprotein emulsifiers from two marine Halomonas species: chemical and physical characterization

AIMS

To partially purify and characterize bioemulsifiers produced by two new marine Halomonas species, TG39 and TG67, and to compare their emulsifying activities with those of commercial emulsifiers.

METHODS AND RESULTS

The production of emulsifiers HE39 and HE67 was achieved from glucose-supplemented marine broth, and recovered by cell removal, concentration by ultrafiltration, precipitation with salt and ethanol, and lyophilization. Purification and chemical analysis revealed both emulsifiers to be glycoproteins of high molecular weight with a notably high content of protein and uronic acids. Physical characterization showed both glycoproteins to effectively emulsify a wide range of food oils under both neutral and acidic pH conditions and withstand acid and high temperature treatment.

CONCLUSIONS

The emulsifying activities of these two new glycoprotein emulsifiers were comparable and, under certain conditions, superior to those produced by commercial emulsifiers tested (xanthan gum, gum arabic and lecithin). They show the highest reported emulsifying activities derived from a Halomonas species.

SIGNIFICANCE AND IMPACT OF THE STUDY

These strains, and the emulsifiers produced, appear to be promising candidates for further development in applications requiring emulsifiers that are natural and compatible to the existing commercial emulsifiers.

Smoking-related attitudes, characteristics, and opinions in a group of young men with asthma

The objective of this study was to examine the attitudes, characteristics, and opinions about smoking of a group of young asthmatic men.

POPULATION AND METHODS

An anonymous, personal questionnaire was administered to 611 young male volunteers who had been diagnosed with asthma (according to the National Heart, Lung, and Blood Institute/World Health Organization Global Initiative for Asthma, 1995) in the respiratory disease and allergy clinics of the Burgos Military Hospital (Spain). This questionnaire contained items related to personal information, asthma characteristics, opinions about smoking, and information related to smoking habits.

RESULTS

Six hundred patients with asthma completed the questionnaire. All were men, mean age 20.16 +/- 3.03 years; 189 (31.5%) were smokers and 16 (2.5%) were ex-smokers. Mean age at onset of regular smoking was 16.46 +/- 2 years. Sixty-five percent (65.07%) smoked fewer than 10 cigarettes per day. Most of the smoking asthmatics had mild asthma (58.9%). Eighty-eight percent (88.3%) had moderate dependence. Many of the smoking asthmatics were contemplating stopping smoking (54%), and 59% had tried before to stop. Concern about health was the main reason given for stopping smoking. Asthmatics who smoked had a higher percentage of smokers among family members, friends, and colleagues than nonsmoking asthmatics. Attitudes toward smoking were more permissive among smoking asthmatics. Only 36.64% of the total had received information about tobacco previously. In the sample group, 7% claimed that they did not smoke but their carbon monoxide concentration in exhaled air was 10 ppm or higher.

CONCLUSIONS

There were no differences in the onset of the smoking habit between asthmatic and nonasthmatic young people. A large percentage of the smoking asthmatics were considering smoking cessation, motivated mainly by their asthma condition. The group as a whole had little previous information about tobacco.