Spontaneous Exciton Collapse in a Strongly Flattened Ellipsoidal InSb Quantum Dot

Electronic and excitonic states in an InSb strongly flattened ellipsoidal quantum dot (QD) with complicated dispersion law are theoretically investigated within the framework of the geometric adiabatic approximation in the strong, intermediate, and weak quantum confinement regimes. For the lower levels of the spectrum, the square root dependence of energy on QD sizes is revealed in the case of Kane's dispersion law. The obtained results are compared to the case of a parabolic (standard) dispersion law of charge carriers. The possibility of the accidental exciton instability is revealed for the intermediate quantum confinement regime. For the weak quantum confinement regime, the motion of the exciton's center-of-gravity is quantized, which leads to the appearance of additional Coulomb-like sub-levels. It is revealed that in the case of the Kane dispersion law, the Coulomb levels shift into the depth of the forbidden band gap, moving away from the quantum confined level, whereas in the case of the parabolic dispersion law, the opposite picture is observed. The corresponding selection rules of quantum transitions for the interband absorption of light are obtained. New selection rules of quantum transitions between levels conditioned by 2D exciton center of mass vertical motion quantization in a QD are revealed. The absorption threshold behavior characteristics depending on the QDs geometrical sizes are also revealed.

[Knowledge of breastfeeding among mothers before maternity discharge]

OBJECTIVES

The aim of our study was to assess the knowledge of parturients about breastfeeding and to analyze the factors influencing this level of knowledge.

METHODS

It was a prospective, descriptive and analytical, cross-sectional study carried out over a period of six months including 500 parturients who gave birth at the maternity unit of the National Center for Maternity and Neonatalogy of Tunis during the period from July to December 2020. Sociodemographic, obstetrical and breastfeeding related data were collected through individual interviews carried out before leaving the postpartum service using a questionnaire written in Tunisian dialectal Arabic.

RESULTS

The average age of the mothers was 31.5 years. Housewives accounted for 73.3 % of cases. Forty-four percent of the women surveyed were first-time mothers. The main source of information was relatives (74.8 %). The prevalence of breastfeeding was 93.8 %. Knowledge about breasfeeding was insufficient in 76.4 % of cases. The level of knowledge was insufficient in particular regarding signs of effective breastfeeding, signs of awakening of the newborn, lactogenesis, and diet of breastfeeding women. Unemployment of the parturient age over 30 and primiparity negatively influenced the knowledge of parturients.

CONCLUSION

The level of knowledge of parturients was heterogeneous but generally insufficient. Health education programs on MA targeting subjects most at risk of insufficient knowledge should be put in place in order to improve the knowledge base and hopefully improve the breastfeeding rates.

Caractéristiques évolutives et facteurs pronostiques du pneumothorax et du pneumomédiastin chez les patients atteints de COVID-19

Introduction

La survenue d’un pneumomédiastin (PM) ou d’un pneumothorax (PNO) est une complication rare au cours du COVID-19 dont les mécanismes physiopathologiques exacts restent mal connus. Toutefois, il s’agit d’une complication grave qui doit être évoqué devant toute aggravation rapide de l’état respiratoire chez ces patients. L’objectif de notre travail est d’étudier les caractéristiques évolutives et les facteurs pronostiques du PM et du PNO associés à une infection à COVID-19.

Méthodes

Il s’agit d’une étude rétrospective réalisée, entre mars et juillet 2021, à l’hôpital militaire de campagne de Sfax, incluant des patients hospitalisés atteints du COVID-19 et qui ont présenté au cours de leurs évolutions un PM ou PNO.

Résultats

Trente-trois patients ont été inclus dans notre étude. Le PM était spontané chez 41,4 % des cas (prévalence à 1,2 %) et secondaire ou iatrogène dans 58,6 % des cas (prévalence à 1,71 %). Un PNO a été associé au PM dans 7 cas (21,2 %). Un PNO isolé spontané a été noté dans 4 cas (12,1 %). Le délai moyen de survenue d’un PM était de 20 jours. La prise en charge du pneumomédiastin était une surveillance clinique et radiologique dans 30,3 % des cas (PM spontané : 66,7 %, PM secondaire ou iatrogène 11,8 %, p = 0,03), le drainage thoracique 21,2 % (40 % pour le PNO spontané, 83,3 % pour le PNO secondaire ou iatrogène, p = 0,1). Quatorze patients (42,4 %) étaient intubés et nécessitaient une ventilation mécanique et 15,2 % ayant nécessités le recours à la ventilation non invasive. La durée moyenne de l’hospitalisation était de 30 jours (27 jours pour le PM spontané, 34 jours pour le PM secondaire ou iatrogène, p = 0,3). L’évolution était favorable dans 42,4 % des cas (83,3 % pour le PM spontané, 17,6 % pour le PM secondaire ou iatrogène, p = 0,001). Une corrélation significative a été trouvé entre la mortalité et la survenue d’un PM (p = 0,01), l’âge (p = 0), la sévérité de l’atteinte radiologique (p = 0,03), la gravité du tableau clinique (l’aggravation de l’état respiratoire p = 0,01 et la présence des signes de compression p = 0,03) et le recours à la ventilation mécanique (p = 0,03).

Conclusion

Le pneumothorax et le pneumomédiastin sont des complications rares mais grave de l’infection pulmonaire par le SARS-CoV-2. Il semble que l’âge, la survenue d’un PM, la sévérité de l’atteinte radiologique, la gravité du tableau clinique et le recours à la ventilation mécanique sont des facteurs de mauvais pronostic.

P6274Role of the nicotinamide riboside kinase 2 in NAD metabolism in the heart in basal and pathological condition

Background

NAD is a major coenzyme in energy metabolism and a substrate for SIRT1 and PARP1 enzymes involved in the response to energy and oxidative stress. We have shown the beneficial effects of nicotinamide riboside (NR), a new type of vitamin B3, on cardiac function and remodelling in a mouse model of dilated cardiomyopathy (DCM) triggered by deletion of the SRF transcription factor in the heart (Srf-HKO) (1). This functional improvement correlated with protection of NAD metabolism and a robust increase in cardiac expression of the Nicotinamide Riboside Kinase 2 (NMRK2) that phosphorylates NR to generate nicotinamide mononucleotide (NMN), an immediate precursor of NAD.

Purpose

We aim to understand the role of the NMRK2-mediated NAD biosynthetic pathway in the heart at baseline and in the DCM context.

Methods

We generated Nmrk2-KO mice that we bred with Srf-HKO to generate double KO mice (db-KO). We analysed cardiac function and remodelling by echocardiography and quantified myocardial NAD levels at baseline and following NR supplementation in food.

Results

Nmrk2KO mice developed a progressive eccentric remodelling of LV and decline in EF with aging. At 24-mo, we observed a reduction of myocardial NAD levels (−40% compared to wild type, p<0.05) and of LVEF (61%, SD 6.3% in Nmrk2-KO vs 78%, SD 1.5% in WT, p<0.05). To assess the contribution of cardiac Nmrk2 induction to NR response in DCM, we compared SrfH-KO and db-KO mice fed with control diet (CD) or NR supplemented diet for 40 days starting at young age (2-mo). NR reduced the extent of LV eccentric remodelling and drop in EF as well as the thinning of the LV posterior wall in both genotypes (2-way ANOVA, diet effect, p<0.01). Myocardial NAD levels were more reduced in db-KO mice under CD diet (−22% compared to control mice, p<0.05) than in Srf-HKO mice (−11%, non-significant), when we previously showed a 25% drop in myocardial NAD in aged SrfHKO mice (1). NR partially preserved cardiac NAD pool in db-KOmice (−10% compared to controls, non-significant). Parallel pathways for NMN synthesis were studied. Nampt gene expression was significantly repressed in db-KO mice fed with CD or NR diet compared to control mice (−50% in average, p<0.01), when there was only a trend toward lower expression in SrfHKO mice (−40% in average, p>0.05). Nmrk1 gene expression trended to increase in all groups compared to wild-type control mice.

Conclusion

We show that NMRK2 pathway plays a role in the maintenance of basal cardiac function and NAD levels when relying on the endogenous myocardial NR pool. In contrast, the beneficial effect of a therapeutic dose of NR is not affected by the lack of NMRK2 suggesting compensation by NMRK1 in the heart and/or that NR beneficial effects on cardiac function could be mediated through its action on systemic metabolism. Aging appears as an aggravating factor for the loss of myocardial NAD coenzyme in DCM.

Acknowledgement/Funding

Agence Nationale pour la Recherche, Fondation de France

[Surgical and endoluminal management of the inflammatory aortitis: A Tunisian center experience]

Non-infectious aortitis is usually due to giant-cell arteritis, Takayasu disease or Behçet disease. The main aortic lesions are stenoses, occlusions and aneurysms in the Takayasu disease and aneurysms in the Behçet disease and giant-cell arteritis. Treatment is based on corticosteroid therapy and surgery. Endoluminal management is now the rule. We report a retrospective descriptive study of 10 patients who underwent surgical or endoluminal management of inflammatory lesions of the aorta between January 2000 and December 2015. There were 4 cases of Takayasu disease and 6 cases of Behçet disease. The aortic lesions were aneurysmal in all of the patients with Behçet disease. In the patients with Takayasu disease, aortic occlusions predominated, associated with other arterial lesions. Four patients with Behçet disease were managed surgically, and 2 patients underwent endovascular repair. All of the patients with Takayasu disease underwent surgery. Two patients died in the postoperative period, and two patients died during long-term follow-up. Systematic screening, as well as regular monitoring of the entire aorta during the follow-up, is necessary due to the frequency of aortic aneurysms.

Subsarcolemmal and interfibrillar mitochondria display distinct superoxide production profiles

Cardiac subsarcolemmal mitochondria (SSM) and interfibrillar mitochondria (IFM) subpopulations display distinct biochemical, morphological, and functional characteristics. Moreover, they appear to be differently influenced during cardiac pathologies or toxic injuries. Although mitochondrial reactive oxygen species seem to play a critical role in cardiac function and diseases, limited information exists about the superoxide production characteristics of these mitochondrial subpopulations. In this work, using direct measurement of superoxide by electron paramagnetic resonance, we showed that differences in superoxide production profiles were present between cardiac IFM and SSM, in terms of intensity and major sites of superoxide generation. In SSM incubated with glutamate plus malate as substrates, the total observed superoxide levels were significantly higher than those observed with IFM, with an important contribution of the NADH-oxidizing site of complex I (site If) and the quinol-oxidizing site of complex III (site IIIQ0). In both IFM and SSM, succinate leads to similar rates of total superoxide levels with a substantial role for contribution of reverse electron transfer. Finally, using two spin probes with different membrane permeabilities, our data on complex III showed direct intra- and extra-mitochondrial superoxide release whereas complex I- and II-dependent superoxide were exclusively released inside the mitochondria, confirming previous studies. Feasibility of this approach to measure intra- and extra-mitochondrial superoxide levels and to characterize distinct superoxide production profiles of cardiac IFM and SSM has been demonstrated.

The use of N-terminal pro-brain natriuretic peptide as a predictor of atrial fibrillation after cardiac surgery

AIM

Atrial fibrillation (AF) is the most common arrhythmia after cardiac surgery with cardiopulmonary bypass (CPB). The value of Nt-pro BNP in predicting AF complicating cardiac surgery is not well studied. Our objective is to determine its predictive role in the occurrence of this complication after heart surgery with cardiopulmonary bypass.

METHODS

It is a prospective observational study including patients proposed for scheduled cardiac surgery with normo-thermal CPB. We performed blood samples for each patient: the first one immediately after the induction of anesthesia and before CPB. The following samples were made at the end of the CBP (H0), 4 hours later (H4) and every day during the first four days (H24, H48, H72 and H96). NT-proBNP and cTnI were measured in each sample. The postoperative AF was defined as any episode of AF documented of a period not less than 15 min recorded in the first 3 days post operative.

RESULTS

The most common cardiovascular complication was the AF (17.5%). Rates of Nt-proBNP were significantly increased in patients who developed this complication. The ROC analysis of NT-proBNP at different times studied for the prediction of AF showed that assays at the end of the CPB and those of the 4th postoperative hour (H4) had the best area under the curve (AUC). A threshold value of 353.5 mg/mL of Nt-proBNP at the end of the CPB has a sensitivity of 71% and a specificity of 84% for the prediction of the AF and an AUC of 0.711. The threshold value (307.5 mg/mL) of Nt-proBNP measured at H4 has the same sensitivity but with a lower specificity (74%) and AUC=0.709.

DISCUSSION AND CONCLUSION

An early Nt pro BNP at H0 or H4, respectively, and with thresholds of 353 and 307 pg/mL could predict the occurrence of the AF. In this case, a primary prevention could be envisaged.

[Management of traumatic aortic rupture. About 37 cases]

OBJECTIVES

The aim of this study was to review our experience in the management of traumatic rupture of the aortic isthmus, to evaluate the results of surgery and endovascular exclusion and to develop an adequate therapeutic strategy based on the existence and severity of associated injuries.

MATERIAL

A series of 37 patients presenting posttraumatic aortic rupture associated with other severe lesions was collected from 2000 to 2012. There were 33 males and four females, mean age 38 years. In this series, 25 patients underwent surgical treatment and 12 endovascular exclusion.

RESULTS

Six patients died during or after surgery. Overall mortality was 16% (24% in the surgery group). The postoperative period was uneventful in all patients treated with the endovascular procedure. Postoperative computed tomography controls at one week, 1 month and 12 months showed good positioning of the stent without endoleakage.

CONCLUSION

Traumatic aortic rupture is often the result of a severe high-energy chest trauma. Other serious injuries are often associated. Results of immediate surgical repair are associated with high morbidity and mortality. The advent of endovascular treatment has revolutionized the treatment of traumatic aortic rupture, especially in patients with a high surgical risk.

[Myoplasty by reversal of the pectoris major muscle in the treatment of mediastinitis. A case report and review of the literature]

Mediastinitis are among the most dreadful infectious complications following cardiac surgery. Their prognosis depends essentially on the precociousness of the diagnosis. In most of the cases, the medical treatment associated with an irrigation drainage is sufficient. But in case of severe sternal dehiscence, plastic surgery becomes necessary in order to fill up the loss with a well-vascularized tissue. We report the case of a 78-year-old patient, chronic bronchitic who presented, after a coronary artery bypass, an aseptic sternal dehiscence necessitating an osteosynthesis, then a Klebsiella pneumoniae mediastinitis with an enlarged sternal necrosis which was treated by bone resection and a myoplasty via reversal of the right pectoris major muscle. The postsurgery course was favourable. Now, after one-year remote, cicatrisation is complete and we have not noticed any infectious recurrence.

[Surgery of aortic coarctation with aneurysm of the ascending aorta and aortic coronary fistula]

Aortic coarctation is rarely associated with an aneurysm of the ascending aorta and an aortic coronary fistula. In this study, we report the case of a 52-year-old man undergoing surgery for an isthmic coarctation who also had an aneurysm of the initial portion of the aorta and an aortic coronary fistula. The diagnosis was clinically suspected and confirmed by vascular catheterism. The first operative stage consisted of treating the coarctation. The second stage was performed two months later to remove the aneurysm and replace the ascending aorta and the aortic valve with a prosthesis. The coronary arteries were then reimplanted. The postoperative results were quite favourable.

Répercussions maternelles et néonatales de l'anesthésie générale par rémifentanil pour césarienne programmée

OBJECTIVE

Opioids are routinely omitted at the induction of general anesthesia for Caesarean delivery because of the risks of respiratory neonatal depression. The short-acting opioid remifentanil may afford advantages at the induction and surgical stimulation, without subsequent neonatal depression.

PATIENTS AND METHODS

In this double-blinded study, 40 at term women undergoing elective Caesarean section and requiring general anaesthesia were allocated randomly to receive either remifentanil (0,5 microg/kg) at the induction of anaesthesia (G1, n=20) or placebo (G2, n=20). Induction of anaesthesia was performed with propofol 2 mg/kg and succinylcholine 1 mg/kg. Anaesthesia was maintained with nitrous oxide in oxygen (50/50%, v/v), propofol (100 microg/kg/min), remifentanil (0.2 microg/kg/min) and atracurium. Neonates were assessed by using Apgar scores, possible respiratory depression, with or without ventilation in the mask or intubation and umbilical cord blood gas (artery: UA and vein: UV). Values are expressed as mean values +/-SD. Pearson's Chi squared and t-test were used for statistical analysis P<0.05 was considered significant.

RESULTS

Maternal systolic pressure, mean pressure and heart rate were significantly higher in G1 at induction. Apgar scores, heart and respiratory rate were similar between groups. Seven episodes of respiratory depressions were noted (3 in G1, 4 in G2). Five neonates required only brief assisted ventilation by face-mask (2 in G1, 3 in G2).

CONCLUSION

Remifentanil (0.5 microg/kg) at the induction of anaesthesia in elective Caesarean section under general anaesthesia can be used without subsequent neonatal depression. However, we believe that further research is necessary to extrapolate these results to a pregnancy carrying an acutely distressed foetus.

[Massive hemoptysis: experience of a surgical unit]

Massive hemoptysis is a clinical entity characterized by its unpredictable and potential lethal course. We studied retrospectively the observations of 25 patients hospitalized in our surgical unit. We collected all the demographic, clinical and surgical data. A male predominance with a sex-ratio of 2,1 was noted. The average age was 45 years, with extremes of 17 and 75. The dominant cause was bronchiectasis. Twenty patients were operated on. The surgery consisted of a pulmonary resection in 9 cases (45%), an atypical lung resection in 4 cases (20%), a resection of an aspergilloma in 2 cases (10%), a kystectomy of hydatic cyst in 4 cases (20%) and one arterial ligature (5%). Five patients (25%) had emergent surgery, and 15 (75%) delayed surgery. Hospital mortality was 20% in the first group and 6.66% in the second. No recurrence of bleeding was observed after an average follow-up of 7 months. Surgery remains a therapy of choice for massive hemopysis. It must as far as possible be avoided during active bleeding.

The effects of drainage with a Redon versus a conventional drain on postoperative pain and blood loss after valve replacements

AIM

The aim of this study was to assess the influence of drainage with a Redon drain versus a conventional drain on postoperative pain and blood loss after valve replacements.

METHODS

After approval by the local Ethics Committee and written informed consent, 30 patients, 20-60 years of age, scheduled for first elective valve replacement were included. After standardized anaesthetic regimens, cardiopulmonary bypass and coagulation therapy procedures and at the end of the operation, the patients were randomly assigned to 1 of 2 groups: (GI, n=15): drainage with 4 Redon drains; (GII, n=15): drainage with 2 conventional drains. Postoperative pain intensity at rest (VAS-R), during coughing and mobilization (VAS-M) in bed was independently evaluated using a visual analogue scale (VAS 100 mm) at 6 hourly intervals until 48 h after admission to the ICU (Ho). All patients received 2 g of paracetamol after obtaining the VAS score (8 g/24 h). No other analgesic agents were used. All patients were submitted to 2D echocardiography to verify the presence of pericardial effusion 24 h after surgery. Values are expressed as means. Pearson's chi squared and ANOVA (for repeated measurements) were used for statistical analysis. P<0.05 was considered significant.

RESULTS

There was no statistically significant difference in the mean postoperative VAS-R and VAS-M, and in the mean postoperative total blood drainage 822.3 ml in GI, versus 704.3 ml in GII. Non pericardial effusion was found, and we did not see side-effects in any of the patients.

CONCLUSIONS

We have shown that drainage with a Redon drains versus a conventional drain does not influence postoperative pain intensity and blood loss after valve replacements.

[Internal trans-Oddi's sphincter fistula drainage of hydatid cysts communicating with the bile ducts]

OBJECTIVE

The purpose of this study was to examine the contribution of internal trans-fistulary drainage without opening the cystic cavity for the treatment of hydatic cyst of the liver.

PATIENTS AND METHODS

Between 1985 and 1990, 14 patients with hydatid cyst of the liver communicating with the bile duct were treated by internal trans-fistulary drainage without opening the hydatic cavity. Choledocoscopy demonstrated good bile flow without a remaining cystic fragment in all cases. The residual cavity was drained via an external drain in the common bile duct. A second hydatic cyst of the liver was also treated in 4 patients.

RESULTS

Internal trans-fistulary drainage was achieved easily. There were two treatment-related postoperative complications: bilary leakage in one patient and infection of the residual cavity leading to septicemia and death in another.

CONCLUSION

Internal trans-fistulary drainage without opening the hydatic cavity is indicated for central hydatic cyst of the liver measuring less than 15 cm with a flexible pericyst and a large biliocystic fistula measuring more than 5 mm. Peroperative choledochoscopy of the hydatic cavity is necessary.

Aortic valve replacement for infective endocarditis in a renal transplant recipient

Renal transplant recipients are more prone to developing infections. We report a 37-year old renal transplant recipient who developed infective endocarditis of the aortic valve, heart failure and renal allograft dysfunction. He underwent aortic valve replacement which was followed by improvement in cardiac as well as allograft function.

[Thoracic aortic aneurysm complicating pseudo-coarctation]

INTRODUCTION

The aneurysm of the descending aorta complicating a pseudocoarctation, itself due to a congenital elongation with kinking of the aorta is a rare entity.

OBSERVATION

We report a case of aortic aneurysm discovered in a 72 years old woman without notable antecedents, which was referred for recurrent bronchitis. The X-ray showed a calcified opacity of the upper mediastinum, 5 cm of large. A thoracic CT-scan evoked the presence of a circulating sacciform aneurysm with calcified walls, developing on the final part of the aortic arch, which was with abnormally ascending way going up to the cervico-thoracic orifice and carrying out an aspect of aortic kinking. The assessment was complemented by a RMI as well as an aortic opacification. A thoracic scintigraphy showed an hypoperfusion of the left lung. The remainder of the cardiac assessment was normal. The patient was operated under femoro-femoral extracorporeal circulation through a left posterolateral thoracotomy of the 4th intercostal space. The examination showed a 7 cm diameter calcified aneurysm of the descending thoracic aorta complicating a tight stenosis in connection with an elongation and a kinking. The upper section of the aorta was shifted towards the pleural dome. The aortic section above aneurism was of normal size whereas the lower section was dilated. The aneurism was excised and a prosthetic graft was carried out. The surgery follow-up was marked by an hemodynamic stability, without neurological deficit. A ventilatory assistance was necessary during 5 days. Currently with 8 months follow-up, the patient goes well.

COMMENTS

A prosthetic replacement in front of this type of aneurism is legitimate given the risk of the occurrence of complications secondary to the pseudocoarctation (arterial hypertension, aortic insufficiency) or to the aneurism itself, dissection or compression of vicinity (pulmonary artery).