Identification of an ATP-sensitive potassium channel in mitochondria

Mitochondria provide chemical energy for endoergonic reactions in the form of ATP, and their activity must meet cellular energy requirements, but the mechanisms that link organelle performance to ATP levels are poorly understood. Here we confirm the existence of a protein complex localized in mitochondria that mediates ATP-dependent potassium currents (that is, mitoK_ATP). We show that-similar to their plasma membrane counterparts-mitoK_ATP channels are composed of pore-forming and ATP-binding subunits, which we term MITOK and MITOSUR, respectively. In vitro reconstitution of MITOK together with MITOSUR recapitulates the main properties of mitoK_ATP. Overexpression of MITOK triggers marked organelle swelling, whereas the genetic ablation of this subunit causes instability in the mitochondrial membrane potential, widening of the intracristal space and decreased oxidative phosphorylation. In a mouse model, the loss of MITOK suppresses the cardioprotection that is elicited by pharmacological preconditioning induced by diazoxide. Our results indicate that mitoK_ATP channels respond to the cellular energetic status by regulating organelle volume and function, and thereby have a key role in mitochondrial physiology and potential effects on several pathological processes.

A High-Throughput Screening Identifies MICU1 Targeting Compounds

Mitochondrial Ca²⁺ uptake depends on the mitochondrial calcium uniporter (MCU) complex, a highly selective channel of the inner mitochondrial membrane (IMM). Here, we screen a library of 44,000 non-proprietary compounds for their ability to modulate mitochondrial Ca²⁺ uptake. Two of them, named MCU-i4 and MCU-i11, are confirmed to reliably decrease mitochondrial Ca²⁺ influx. Docking simulations reveal that these molecules directly bind a specific cleft in MICU1, a key element of the MCU complex that controls channel gating. Accordingly, in MICU1-silenced or deleted cells, the inhibitory effect of the two compounds is lost. Moreover, MCU-i4 and MCU-i11 fail to inhibit mitochondrial Ca²⁺ uptake in cells expressing a MICU1 mutated in the critical amino acids that forge the predicted binding cleft. Finally, these compounds are tested ex vivo, revealing a primary role for mitochondrial Ca²⁺ uptake in muscle growth. Overall, MCU-i4 and MCU-i11 represent leading molecules for the development of MICU1-targeting drugs.

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An HTS identifies MCU-i4 and MCU-i11 as negative modulators of the MCU

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MCU-i4 and MCU-i11 bind MICU1

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MICU1 is required for the activity of MCU-i4 and MCU-i11

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MCU-i4 and MCU-i11 impair muscle cell growth

Possible synergistic effect of metformin and enalapril on the development of hyperkaliemic lactic acidosis

A 71 year old hypertensive, non insulin-dependent diabetic patient with moderate renal insufficiency taking 500 mg/d of metformin and 5 mg/d of enalapril, developed metabolic acidosis characterized by fairly elevated anion gap, hyperchloremia, severe hyperkaliemia, normal plasma level of 3-hydroxybutyric acid, absence of ketonuria and high plasma level of lactic acid. This biochemical feature allowed us to ascribe the pathogenesis of metabolic acidosis, both to the increased plasma level of lactic acid and to the type IV renal tubular acidosis syndrome, the precipitating factor being an infection of urinary tract (as we assumed on the basis of the urine culture). The patient was dehydrated and lethargic; the ECG revealed the presence of nonparoxysmal junctional tachycardia. The clinical evolution was favorable under the treatment with an infusion of isotonic saline solutions, mild alkalinizing solutions, low-dose regular insulin and antibiotics. It is likely that metformin and enalapril, regularly taken by this nephropathic patient, could have played an iatrogenic role, even if the doses were low. This case highlights the importance of complying with the contraindications of these drugs, to avoid the rare but reported life-threatening complications of metformin administration.

The mitochondrial ATP-dependent potassium channel (mitoKATP) controls skeletal muscle structure and function

MitoKATP is a channel of the inner mitochondrial membrane that controls mitochondrial K+ influx according to ATP availability. Recently, the genes encoding the pore-forming (MITOK) and the regulatory ATP-sensitive (MITOSUR) subunits of mitoKATP were identified, allowing the genetic manipulation of the channel. Here, we analyzed the role of mitoKATP in determining skeletal muscle structure and activity. Mitok-/- muscles were characterized by mitochondrial cristae remodeling and defective oxidative metabolism, with consequent impairment of exercise performance and altered response to damaging muscle contractions. On the other hand, constitutive mitochondrial K+ influx by MITOK overexpression in the skeletal muscle triggered overt mitochondrial dysfunction and energy default, increased protein polyubiquitination, aberrant autophagy flux, and induction of a stress response program. MITOK overexpressing muscles were therefore severely atrophic. Thus, the proper modulation of mitoKATP activity is required for the maintenance of skeletal muscle homeostasis and function.

Fetal Doppler Parameters at Term in Pregnancies Affected by Gestational Diabetes: Role in the Prediction of Perinatal Outcomes

OBJECTIVE

 The timing of delivery for women affected by gestational diabetes (GDM) is still controversial. Good clinical practice often suggests offering induction of labor at term in order to reduce the complications associated with this condition, while recent evidence supports expectant management. Fetal Doppler parameters represent a validated tool for testing fetal well-being at term and can select pregnancies that need increased surveillance. The aim of the present study was to evaluate the role of fetal Doppler parameters at term for the prediction of pregnancy outcomes in patients affected by GDM.

METHODS

 Prospective cohort study in a single center. Evaluation of umbilical artery (UA) PI, middle cerebral artery (MCA) PI, cerebroplacental ratio (CPR) and umbilical-to-cerebral ratio (UCR) at > 37 weeks of gestation in singleton, morphologically normal pregnancies affected by GDM, was performed in order to estimate the association between ultrasound measurements at term and perinatal outcome. Regression linear analysis was used to estimate the association between fetal Doppler parameters and neonatal pH, neonatal Apgar score, neonatal weight and a composite adverse outcome. The receiver operating characteristic (ROC) curve was used to estimate the possible predictive value of the above association.

RESULTS

 Our results on 130 women showed MCA PI to be the best predictor of perinatal outcomes in terms of low Apgar score at the 1st minute (p = 0.00), pH (p = 0.02) and composite adverse outcome (p = 0.05). UCR showed a significant correlation with neonatal pH (p = 0.02). No significant correlations for UA PI and CPR MoMs have been demonstrated in our population. However, the small sample size is a limitation of the study.

CONCLUSION

 Evaluation of MCA Doppler and eventually UCR at term can be a useful tool to discriminate pregnancies affected by GDM that can benefit from IOL before 41 weeks in order to reduce complications related to this condition.

Photosynthetic properties of leaves of a yellow green mutant of wheat compared to its wild type

We investigated several photosynthetic parameters of a virescent mutant of durum wheat and of its wild-type. Electron transport rate to ferricyanide was the same in the two genotypes when expressed on leaf area basis while O2 evolution of the leaf tissue in saturating light and CO2 was slightly higher in the yellow genotype. RuBPCase was also slightly higher. Quantum yield per absorbed light was similar in the two genotypes. P700 and Cyt f were less concentrated in the mutant while PS II was only marginally lower. The light response curve of CO2 assimilation indicated higher level of photosynthesis of the mutant in high light, which corresponded to a lower non-photochemical quenching compared to the wild-type. It is concluded that the reaction centres, cyt f and chlorophyll are not limiting factors of electron transport in wheat seedlings and that electron transport capacity is in excess with respect to that needed for driving photosynthesis. Since the differences in photosynthesis reflect differences in RuBPCase activity, it is suggested that this enzyme limits photosynthesis in wheat seedlings also at high light intensities.

Maternal position during the second stage of labor and maternal-neonatal outcomes in nulliparous women: a retrospective cohort study

BACKGROUND

The existing evidence is insufficient to draw conclusions about the association between maternal position in labor and obstetrical outcomes.

OBJECTIVE

This study aimed to evaluate the effects of different maternal positions during the second stage of labor among women with and those without epidural analgesia on important obstetrical outcomes including perineal damage.

STUDY DESIGN

In this retrospective cohort study, we collected data of women who delivered vaginally over a 2-year period. The associations between maternal and gestational characteristics and several obstetrical outcomes were analyzed. We considered perineal damage as the primary outcome. Secondary outcomes were the incidence of operative vaginal births, duration of fetal descent, intrapartum blood loss, and 1-minute and 5-minutes Apgar scores.

RESULTS

A total of 2240 nulliparous, at-term pregnancies were included. Of those, 76.9% gave birth in a supine position and 23.1% gave birth in alternative positions. The results showed that regardless of the use of epidural analgesia, nonsupine positions in the second stage of labor are associated with a significant reduction in the risk of both episiotomy and perineal damage to any degree (P<.0001) and to a reduction in the duration of fetal descent (Spearman rho, 9.17; confidence interval, 3.07-15.32; P=.003). No statistically significant differences were found in the 1-minute and 5-minutes Apgar score between the 2 groups.

CONCLUSION

Our results show that nonsupine positions in the second stage of labor and at the time of birth are associated with a significant increase in having an intact perineum and a reduction in any perineal trauma and in the need for an episiotomy regardless of the use of epidural analgesia.

The impact of placental anastomoses and umbilical cord insertions' sites on monochorionic twin pregnancy outcomes: Evidence from color-dye injection studies

INTRODUCTION

Our knowledge of monochorionic pregnancies' complications is largely based on the extensive ongoing research on monochorionic placental structure. Previous studies on the concordance of umbilical cord insertions are limited. This study aimed to evaluate placental anastomoses and cord insertions as independent risk factors for neonatal adverse outcomes.

METHODS

This was a prospective study conducted at Fondazione Policlinico Universitario Agostino Gemelli IRCCS, Rome, Italy from April 2021 to December 2022. Seventy-six women with a monochorionic pregnancy were enrolled at their first-trimester scan. After delivery, all placentas that were confirmed to be monochorionic were analyzed according to standard protocols, including those of complicated monochorionic twin pregnancies. The primary outcomes were a Composite Monochorionic Pregnancy Outcome (CMPO) and a Composite Neonatal Adverse Outcome (CNAO). The secondary outcome was the birth weight discordance between the neonates.

RESULTS

The CMPO occurred in 15.8 % pregnancies, and the CNAO occurred in 67.1 % pregnancies. The analysis confirmed a significant association between velamentous cord insertions and neonatal adverse events (p = 0.003). Also, a significant positive association (p = 0.0326) between twin birth weight discordance and discordance in twins umbilical cord insertions' sites was found. No significant association between the number and type of the anastomoses and both the CMPO or CNAO was detected.

DISCUSSION

Our data suggest that the routine sonographic assessment of umbilical cords' insertion sites during the first trimester could be helpful in predicting fetal and neonatal adverse events. We believe that this sonographic assessment should start to be implemented in our routine care of monochorionic pregnancies.

Anaphylaxis in Adolescent/Adult Patients Treated in the Emergency Department: Differences Between Initial Impressions and the Definitive Diagnosis

OBJECTIVES

To contrast the initial suspected etiology of anaphylaxis with the postworkup diagnosis in patients attended at the emergency department (ED) of a tertiary-level hospital in Spain and to investigate the incidence, causes, and management of anaphylaxis.

METHODS

We performed an observational study of patients aged more than 15 years who came to the ED with anaphylaxis between 2009 and 2010. All clinical records from the ED were reviewed. We recorded data on clinical management, the etiology proposed by the attending emergency physician, and the cause reported by the patient. The findings were compared with the diagnosis reached after the allergy workup.

RESULTS

The incidence of anaphylaxis was 0.08%. The most common manifestation was skin-mucosal symptoms (98.3%). Anaphylaxis was diagnosed in the ED in only 44% of the cases, regardless of severity. Only 39.7% received epinephrine, which was administered more frequently when the ED physician diagnosed anaphylaxis, regardless of severity. A total of 60 patients were subsequently seen at the allergy department. The final etiology differed from the initial suspicion in the ED in 45% of cases. The frequency of anaphylaxis of uncertain origin decreased from 33.3% to 13.3%. After the allergy workup, drugs (41.7%) were considered the main cause of anaphylaxis, followed by food (25%).

CONCLUSIONS

The incidence of anaphylaxis (0.08%) was double that estimated in the ED. Anaphylaxis is underdiagnosed. A correct diagnosis conditions the administration of epinephrine, regardless of the severity of symptoms. The real etiology of anaphylaxis should only be proposed after an allergy workup, which is recommended in all cases, as the real cause can differ considerably from the initial impression in the ED.

[Efficacy of 0.1 mg of subarachnoid morphine combined with bupivacaine on postoperative analgesia in total hip arthroplasty]

OBJECTIVES

To analyze the analgesic efficacy, safety and side effects of subarachnoid morphine (0.1 mg) with bupivacaine in patients undergoing total hip arthroplasty.

PATIENTS AND METHODS

Thirty patients scheduled for total hip replacement under spinal anesthesia with bupivacaine were randomly assigned to two groups according to whether local anesthetic with 0.1 mg subarachnoid morphine was also provided or not (group M [n = 15] and group S ņ = 15[, respectively). Top-up analgesia with morphine was available through a patient-controlled device. Postoperative pain was assessed on a visual analogue scale (VAS) and consumption of intravenous morphine in the first 48 hours after surgery was recorded.

RESULTS

VAS scores (mean +/- SD) were significantly lower in the first six hours in group M, but no differences between the two groups were observed thereafter. Total consumption of morphine at 48 hours was much lower in group M (6.80 +/- 7.74 mg) than in group S (31.38 +/- 13.17 mg). The incidence of nausea was high in both groups (46%). Slight pruritus affected 26.6% of patients in group M. Urinary retention necessitating temporary placement of a catheter was observed only in group M, where the incidence was 35.7%. No cases of respiratory depression occurred. Drowsiness was observed in 26.6% of patients in group S in comparison with 6.6% in group M.

CONCLUSIONS

Combining 0.1 mg morphine and bupivacaine for total spinal anesthesia during hip arthroplasty significantly decreased the consumption of intravenous morphine during the first 48 hours after surgery. No respiratory depression occurred and the only side effects were urinary retention and mild pruritus and drowsiness.

Ductus Venosus Agenesis in Monochorionic Twin Pregnancies Complicated by Fetal Growth Restriction: When to Deliver?

Introduction: The prevalence of ductus venosus agenesis (ADV) in singleton pregnancies ranges from 0.04% to 0.15%, while its prevalence in twins remains largely unknown. To our knowledge, in the literature, there is only a single case report of a monochorionic diamniotic (MCDA) pregnancy complicated by ADV. Fetuses with ADV are at increased risk for congenital cardiac disease, heart failure, and fetal growth restriction (FGR). Consequently, these pregnancies have a heightened risk of experiencing an adverse outcome, like stillbirth and neonatal or infant death. Closer antenatal monitoring is warranted when ADV is suspected. Currently, there are no guidelines regarding the standard of care in cases of ADV and no recommendations for the timing of delivery in either singleton or twin pregnancies. Cases: This study aims to provide a comprehensive overview of the management of twin pregnancies complicated by ADV, featuring two cases of MC twins with concurrent sFGR and ADV in one twin. Discussion: These pregnancies experienced completely different outcomes, underscoring the necessity for personalized management tailored to the specific risk factors present in each pregnancy. Typically, in MCDA pregnancies with severe sFGR (type II and III), delivery represents the most reasonable option when venous Doppler abnormalities are identified. However, the absence of the DV complicates the management and the process of decision-making regarding the timing of delivery in cases of sFGR and ADV. We emphasize that effective decision-making should be guided by the presence of additional risk factors, including velamentous insertion, significant estimated fetal weight discordance, and progressive deterioration of the Doppler over time. Conclusions: Our experience suggests that these factors are strongly correlated with poorer outcomes. Given this context, could it be acceptable, in the case of MC pregnancy complicated by severe sFGR and ADV, with worsening findings and additional risk factors (e.g., velamentous insertion, severe birth weight discrepancy), to anticipate the time of delivery starting from 30 weeks of gestational age?

Recommendations for the evaluation and management of the anticipated and non-anticipated difficult airway of the Societat Catalana d'Anestesiologia, Reanimació i Terapèutica del Dolor, based on the adaptation of clinical practice guidelines and expert consensus

The Airway Division of the Catalan Society of Anaesthesiology, Intensive Care and Pain Management (SCARTD) presents its latest guidelines for the evaluation and management of the difficult airway. This update includes the technical advances and changes observed in clinical practice since publication of the first edition of the guidelines in 2008. The recommendations were defined by a consensus of experts from the 19 participating hospitals, and were adapted from 5 recently published international guidelines following an in-depth analysis and systematic comparison of their recommendations. The final document was sent to the members of SCARTD for evaluation, and was reviewed by 11 independent experts. The recommendations, therefore, are supported by the latest scientific evidence and endorsed by professionals in the field. This edition develops the definition of the difficult airway, including all airway management techniques, and places emphasis on evaluating and classifying the airway into 3 categories according to the anticipated degree of difficulty and additional safety considerations in order to plan the management strategy. Pre-management planning, in terms of preparing patients and resources and optimising communication and interaction between all professionals involved, plays a pivotal role in all the scenarios addressed. The guidelines reflect the increased presence of video laryngoscopes and second-generation devices in our setting, and promotes their routine use in intubation and their prompt use in cases of unanticipated difficult airway. They also address the increased use of ultrasound imaging as an aid to evaluation and decision-making. New scenarios have also been included, such as the risk of bronchoaspiration and difficult extubation Finally, the document outlines the training and continuing professional development programmes required to guarantee effective and safe implementation of the guidelines.