Characterization of neutral sphingomyelinase activity and isoform expression in rodent skeletal muscle mitochondria

Skeletal muscle is composed of fiber types that differ in mitochondrial content, antioxidant capacity, and susceptibility to apoptosis. Ceramides have been linked to oxidative stress-mediated apoptotic intracellular signalling and the enzyme neutral sphingomyelinase (nSMase) is, in part, responsible for generating these ceramides through the hydrolysis of sphingomyelin. Despite the role of ceramides in mediating apoptosis, there is a gap in the literature regarding nSMase in skeletal muscle mitochondria. This study aimed to characterize total nSMase activity and individual isoform expression in isolated subsarcolemmal (SS) mitochondria from soleus, diaphragm, plantaris, and extensor digitorum longus (EDL). Total nSMase activity did not differ between muscle types. nSMase2 content was detectable in all muscles and higher in EDL, soleus, and plantaris compared to diaphragm whereas nSMase3 was undetectable in all muscles. Finally, total nSMase activity positively correlated to nSMase2 protein content in soleus but not the other muscles. These findings suggest that nSMase associated with SS mitochondria may play a role in intracellular signalling processes involving ceramides in skeletal muscle and nSMase2 may be the key isoform, specifically in slow twitch muscle like soleus. Further studies are needed to fully elucidate the specific contribution of nSMase, along with the role of the various isoforms and mitochondrial subpopulation in generating mitochondrial ceramides in skeletal muscle, and its potential effects on mediating apoptosis.

Influence of clinical suspicion on CT accuracy of acute mesenteric ischemia: Retrospective study of 362 patients

PURPOSE

Acute mesenteric ischemia (AMI) may be underdiagnosed when not clinically suspected before CT is performed. We assessed the influence of a clinical suspicion of AMI on the CT accuracy.

METHOD

This retrospective single-centre study included patients who underwent CT in 2014-2019 and had clinically suspected AMI and/or confirmed AMI. CT protocols were adapted based on each patient's presentation and on findings from unenhanced images. The CT protocol was considered optimal for AMI when it included arterial and portal venous phases. CT protocols, accuracy of reports, and outcomes were compared between the groups with and without suspected AMI before CT.

RESULTS

Of the 375 events, 337 (90 %) were suspected AMI and 66 (18 %) were AMI, including 28 (42 %) with and 38 without suspected AMI. These two groups did not differ significantly regarding the medical history, clinical presentation, or laboratory tests. The CT protocol was more often optimal for AMI in the group with suspected AMI (26/28 [93 %] vs. 28/38 [74 %], p = 0.046). Diagnostic accuracy was not different between groups with and without suspected AMI (26/28 [93 %] vs. 34/38 [90 %], p = 1.00). However, it was lower in the group without suspicion of AMI when the CT protocol was not optimal for AMI (27/28 [96 %] vs 7/10 [70 %], p = 0.048).

CONCLUSIONS

The negative influence of not clinically suspecting AMI can be mitigated by using a tailored CT protocol.

The effect of cardiolipin side chain composition on cytochrome c protein conformation and peroxidase activity

Skeletal muscle, a highly active tissue, makes up 40% of the total body weight. This tissue relies on mitochondria for ATP production, calcium homeostasis, and programed cell death. Mitochondrial phospholipid composition, namely, cardiolipin (CL), influences the functional efficiency of mitochondrial proteins, specifically cytochrome c. The interaction of CL with cytochrome c in the presence of free radicals induces structural and functional changes promoting peroxidase activity and cytochrome c release, a key event in the initiation of apoptosis. The CL acyl chain degree of saturation has been implicated in the cytochrome c to cytochrome c peroxidase transition in liposomal models. However, mitochondrial membranes are composed of differing CL acyl chain composition. Currently, it is unclear how differing CL acyl chain composition utilizing liposomes will influence the cytochrome c form and function as a peroxidase. Thus, this study examined the role of CL acyl chain saturation within liposomes broadly reflecting the relative CL composition of mitochondrial membranes from healthy and dystrophic mouse muscle on cytochrome c conformation and function. Despite no differences in protein conformation or function between healthy and dystrophic liposomes, cytochrome c's affinity to CL increased with greater unsaturation. These findings suggest that increasing CL acyl chain saturation, as implicated in muscle wasting diseases, may not influence cytochrome c transformation and function as a peroxidase but may alter its interaction with CL, potentially impacting further downstream effects.

From benign adrenal incidentaloma to adrenocortical carcinoma: an exceptional random event

New European guidelines for the management of adrenal incidentalomas were recently released. One of the most novel recommendations is to stop following patients when they present a typical, small and non-secreting adenoma. We report here the case of a 71-year-old man with such an adenoma, who developed an adrenocortical carcinoma (ACC) fourteen years later, with subsequent metastases and death. Clinically, he had a normal blood pressure and no sign of hormonal hypersecretion. The hormonal work-up showed no hormone excess: urinary free cortisol level was normal, the diurnal cortisol rhythm was respected and urinary catecholamine metabolites levels were normal. Computed tomography (CT) scan showed a homogeneous lesion, with a low density. The lesion remained unchanged during the five years of follow-up. Eight years after the last CT, a large right heterogeneous adrenal mass was incidentally discovered during an ultrasound examination. On CT scan, it was a 6 cm heterogeneous tumor. On hormonal work-up, there was no secretion. The patient was operated of an adrenalectomy, and the histology described an ACC with a Weiss score at 8, with no benign contingent. To our knowledge, this is the first case of an ACC occurring in a patient with prior adrenal imaging showing a typical benign adenoma.

[Embolization of a ruptured pseudo-aneurysm of the uterine artery at 26weeks of gestation: Materno-fetal consequences; a case-report]

Rupture of a uterine artery pseudo-aneurysm during pregnancy is a rare condition with potential life-threatening complications, and management should take into account the fetal impact of the therapeutic choice. We report the case of a 2cm left uterine artery pseudo-aneurysm revealed by pelvic pain, in a 30-year-old pregnant woman at 26(+0)weeks of gestation (WG). Diagnosis was suspected at ultrasound scan, and confirmed with Magnetic Resonance angiography that showed signs of pre-rupture. An emergency selective embolization attempted in utero allowed the complete exclusion of the aneurysmal sac. The patient gave birth one month later to a girl at 31(+1)WG, initially managed by neonatologists, who is currently in good health.

[A pancreatic pseudocyst associated with three simultaneous hemorragic complications]

The onset of secondary hemorrhagic complications with the development of pancreatic pseudocysts is rare but has a high mortality rate. Management of the hemorrhagic complications of pancreatic pseudocysts is surgical despite the contribution of arterial embolization. We report the observation of a 59-year-old patient who had presented an episode of acute pancreatitis 1 month before consulting for abdominal pain associated with an episode of melena. The CT showed a pancreatic pseudocyst complicated by an intracystic tear, a splenic artery aneurysm in the Wirsung canal, and rupture of the spleen. These three lesions were treated simultaneously with left splenopancreatectomy starting with the splenic vessels. The simultaneous onset of three hemorrhagic complications of a pseudocyst is exceptional and has never been described to our knowledge.

[Radiologically-guided hysterosalpingography and tubal catheterization]

Radiological exploration of hypofertility by means of hysterosalpingography is a method still valid but no longer sufficient. Tubal catheterization has thus become a necessary complementary exam in order to eliminate the pseudo-obturations of hysterosalpingography and, in case of proximal tubal obstructions, to obtain pregnancies. The conditions for the realization of hysteroalpingography and tubal catheterization are hereby described, with emphasis on the rigorous technique that is required together with careful listening to the patients.

[Coronary artery implantation and course abnormalities: the contribution of multislice CT]

Abnormalities in coronary artery origin and course are rare and often asymptomatic. However, visualizing them is of great interest because they can be responsible for iatrogenic trauma during cardiac surgery, and, for some of them, for myocardial infarction, which can lead to sudden death. We show the contribution of multislice CT in the positive diagnosis of these anatomic variations and in the differential diagnosis between benign and malignant forms, potentially responsible for myocardial ischemia.

[Imaging of non-traumatic intracerebral hematoma]

Intracerebral hematoma is mainly due to the spontaneous rupture of small vessels damaged by chronic hypertension or amyloid angiopathy. In some cases, intracerebral hemorrhage may be associated with a vascular malformation, a tumor, venous thrombosis or hemorrhagic transformation of a cerebral infarct. The objective of brain imaging is to identify the hematoma according to its different stages and to find a potential underlying cause because of the risk of recurrence and the possibilities of treatment. In emergency, a diagnosis of hematoma may be obtained by CT scan or MRI but the etiologic work-up requires early MRI. According to the patient's age, the medical history and the location of the hematoma, it may be necessary to perform conventional angiography in order to exclude an intracranial vascular malformation. The aim of this review is to detail the different aspects of intracerebral hemorrhages and to discuss the main causes that can be found at brain imaging.