Retrograde Mitochondrial Transport Is Essential for Organelle Distribution and Health in Zebrafish Neurons

In neurons, mitochondria are transported by molecular motors throughout the cell to form and maintain functional neural connections. These organelles have many critical functions in neurons and are of high interest as their dysfunction is associated with disease. While the mechanics and impact of anterograde mitochondrial movement toward axon terminals are beginning to be understood, the frequency and function of retrograde (cell body directed) mitochondrial transport in neurons are still largely unexplored. While existing evidence indicates that some mitochondria are retrogradely transported for degradation in the cell body, the precise impact of disrupting retrograde transport on the organelles and the axon was unknown. Using long-term, in vivo imaging, we examined mitochondrial motility in zebrafish sensory and motor axons. We show that retrograde transport of mitochondria from axon terminals allows replacement of the axon terminal population within a day. By tracking these organelles, we show that not all mitochondria that leave the axon terminal are degraded; rather, they persist over several days. Disrupting retrograde mitochondrial flux in neurons leads to accumulation of aged organelles in axon terminals and loss of cell body mitochondria. Assays of neural circuit activity demonstrated that disrupting mitochondrial transport and function has no effect on sensory axon terminal activity but does negatively impact motor neuron axons. Taken together, our work supports a previously unappreciated role for retrograde mitochondrial transport in the maintenance of a homeostatic distribution of mitochondria in neurons and illustrates the downstream effects of disrupting this process on sensory and motor circuits.SIGNIFICANCE STATEMENT Disrupted mitochondrial transport has been linked to neurodegenerative disease. Retrograde transport of this organelle has been implicated in turnover of aged organelles through lysosomal degradation in the cell body. Consistent with this, we provide evidence that retrograde mitochondrial transport is important for removing aged organelles from axons; however, we show that these organelles are not solely degraded, rather they persist in neurons for days. Disrupting retrograde mitochondrial transport impacts the homeostatic distribution of mitochondria throughout the neuron and the function of motor, but not sensory, axon synapses. Together, our work shows the conserved reliance on retrograde mitochondrial transport for maintaining a healthy mitochondrial pool in neurons and illustrates the disparate effects of disrupting this process on sensory versus motor circuits.     

Primary vs delayed primary closure in patients undergoing lower limb amputation following trauma: A randomised control study

Lower limb crush injury is a major source of mortality and morbidity in trauma patients. Complications, especially surgical site infections (SSIs) are a major source of financial burden to the institute and to the patient as it delays rehabilitation. As such, every possible attempt should be made to reduce any complications. We, thus, aimed to compare the outcomes in early vs delayed closure of lower extremity stumps in cases of lower limb crush injury requiring amputation, so as to achieve best possible outcome. A randomised controlled study was conducted in the Division of Trauma Surgery & Critical Care at Jai Prakash Narayan Apex Trauma Centre, All India Institute of Medical Sciences, New Delhi from 1 September 2018 to 30 June 2019 and included patients undergoing lower limb amputation below hip joint. Patients were randomised in two groups, in one group amputation stump was closed primarily, while in the second group delayed primary closure of stump was performed. We compared rate of SSI, length of hospital stay, and number of surgeries in both the groups. Fifty‐six patients with 63 amputation stumps were recruited in the study. Mean age of patients in the study was 34 years, of which about 95% patients were males. The most common mechanism of injury was road traffic injury in 66% of patients. Mean injury severity score was 12.28 and four patients had diabetes preoperatively. Total 63 extremities were randomised with 30 cases in group I and 33 cases in group II as per computer‐generated random number. Above knee amputations was commonest (57.14%) followed by below knee amputations (33.3%). Two patients died in the current study. In group I, In‐hospital infection was detected in 7 cases (23.3%) and in group II 9 cases (27.3%) had SSI during hospital admission (P > .05). Mean hospital stay in group I was 10.32 ± 7.68 days and in group II was 11 ± 8.17 days (P > .05). Road traffic injuries and train‐associated injuries are a major cause of lower limb crush injuries, leading to limb loss. Delayed primary closure of such wounds requires extra number of surgical interventions than primary closure. There is no difference in extra number of surgical interventions required in both the groups. Thus, primary closure can be safely performed in patients undergoing lower limb amputations following trauma, provided that a good lavage and wound debridement is performed.     

Facteurs de protection dans les conduites d’alcoolisation chez les étudiants de l’université Saint-Esprit de Kaslik au Liban. Étude transversale effectuée sur des étudiants séminaristes et non séminaristes

ObjectivesAlcohol consumption is facilitated in university students by personal risk factors such as initiation with the substances at an early age, a low self-esteem, a lack of social aptitudes and heredity. Protective factors are characteristics of the personality like optimistic attitude towards the future, good coping strategies, good self-esteem and good capacity of resilience. The objective of our study consists in comparing the alcohol consumption of subjects between 18 and 25 years old within the Holy Spirit University of Kaslik in Beirut. We postulate that the alcohol consumption and the protection factors in the same university vary, as the students are seminarists or not. We tried to see if the seminarists students have lesser alcohol consumption (binge drinking, abuse, dependence) than none seminarists students and to see if they have personal psychological protection factors (optimism, high self-esteem, positive coping strategies to resolve the problems and resilience) higher than none seminarists students.Subjects and methodsOur study concern a Lebanese sample of 200 students of the Holy Spirit University of Kaslik, Lebanese Francophone University, aged between 18 and 25 years, distributed on four faculties (theology, management, science and medicine) of 50 persons each one. The students were informed and agreed to pass two anonymous questionnaires: the first one help to detect subjects having alcohol drinking (binge drinking, abuse and dependence) whose a part corresponds to the test AUDIT measuring the alcoholic dependence; and the second allows evaluating personal psychological factors of protection (optimism, good self-esteem, positive coping strategies and resilience) whose a part concerning the self-esteem is the one of Rosenberg, the part relating to the coping strategies is inspired by the “Brief cope” scale of Carver; the part concerning the optimism is inspired by the LOT “Test Life orientation” of Schier and Carver and the part relating to the resilience is inspired by “the control and the self-resilience” scale.ResultsTheology students have personal factors of protection, which protect them from alcohol drinking: higher optimism than others, more positive coping strategies, a better resilience and a good self-esteem more than those in other faculties. This differentiates them from other students concerning the risk use and the “binge drinking” and did not significantly differentiate them concerning the abuse and the dependence. The binge drinking seems to be significantly higher at the students in management, sciences and medicine. Their search for domination, which accompanies the competition between each others, where it is socially “virile” to drink important quantities of alcohol around games, can influence their behavior. So, we can understand why such behaviors do not seem to interest the seminarists. The risk use on the test of the AUDIT seems to be significantly lower in seminarists students than in sciences and management. This can be explained by their less frequent use of substances to resolve their conflicts and their use of coping strategies such as prayers and by their vision in the life is based on the hope, faith and carrier of optimism. The major problem of Lebanese students remains the “binge drinking”.ConclusionIt would be interesting to propose interventions within the university. Talking groups could be settled to help them talking about their own consumption of alcohol.     

NG2 colocalizes with axons and is expressed by a mixed cell population in spinal cord lesions

The NG2 proteoglycan is of general interest after spinal cord injury because it is expressed by oligodendrocyte progenitors (OPCs), which contribute to central nervous system remyelination; however, NG2 may inhibit axon regeneration. We and others have examined the spatiotemporal expression of NG2 after spinal cord injury (SCI). Here, we extend those observations and provide a comprehensive analysis of the distribution, phenotype, and colocalization of NG2 cells with axons in a clinically relevant model of spinal contusion. Because contusion models mimic the majority of human SCI, this information is important for understanding endogenous processes that promote and/or prevent repair. The data demonstrate that NG2 levels rise significantly between 3 and 7 days postinjury (dpi) and remain elevated chronically throughout the lesions. NG2 within the lesions could be derived from an array of infiltrating cells; thus, a panel of antibodies was used to investigate NG2 cell phenotypes. First, platelet-derived growth factor-alpha receptor (PDGFalphaR) colocalization was examined because OPCs normally express both markers. PDGFalphaR cells were present in lesions at all times examined. However, only 37% of NG2 cells coexpressed PDGFalphaR at 14 dpi, which dropped to <1% by 70 dpi. This contrasts with the nearly complete overlap in spared tissue surrounding the lesion. In contrast, 40% to 60% of NG2 cells expressed p75 and approximately 84% expressed Sox10, suggesting that many NG2 cells were nonmyelinating Schwann cells. Despite rising levels of NG2, we noted robust and sustained axon growth into the lesions, many of which were located along NG2 profiles. Thus, spinal contusion produces an NG2-rich environment into which axons grow and in which the source of NG2 appears considerably different from that in surrounding spared tissue.     

Role of hypoxia-inducible factor-1α in angiogenic–osteogenic coupling

Angiogenesis and osteogenesis are tightly coupled during bone development and regeneration. The vasculature supplies oxygen to developing and regenerating bone and also delivers critical signals to the stroma that stimulate mesenchymal cell specification to promote bone formation. Recent studies suggest that the hypoxia-inducible factors (HIFs) are required for the initiation of the angiogenic–osteogenic cascade. Genetic manipulation of individual components of the HIF/vascular endothelial growth factor (VEGF) pathway in mice has provided clues to how coupling is achieved. In this article, we review the current understanding of the cellular and molecular mechanisms responsible for angiogenic–osteogenic coupling. We also briefly discuss the therapeutic manipulation of HIF and VEGF in skeletal repair. Such discoveries suggest promising approaches for the development of novel therapies to improve bone accretion and repair.     

Long-term deficits of preterm birth: evidence for arousal and attentional disturbances.

OBJECTIVE: Quantitative measures of pre-attentional, attentional and frontal lobe processes were compared to evaluate quantitative measures of these deficits in Ex-Preterm vs. Ex-Term adolescents. METHODS: We compared 43 Ex-Preterm with 26 Ex-Term adolescents using the P50 auditory potential, the Psychomotor Vigilance Task (PVT), a reaction time (RT) test, and Near Infrared Spectroscopy (NIRS). RESULTS: The mean amplitude (+/-SE) of the P50 amplitude was similar in the Ex-Preterm (1.8+/-1.4 microV) vs. Ex-Term adolescents (1.8+/-0.6 microV, df = 68, F = 0.05, p = 0.8), but the Ex-Preterm group showed a trimodal distribution in amplitude (High, 3.3+/-0.4 microV, df=42.25, F=19.2, p < 0.01; Medium, 1.7+/-0.1 microV, df = 39, F = 0.41, p = 0.53; Low, 0.7+/-0.1 microV, df = 40, F = 49.5, p < 0.01) suggested by statistically significant variance between populations (Kolmogorov-Kuiper test, df = 42.25, F = 5.4, p < 0.01). Mean RT was longer in Ex-Preterm (250+/-8 ms) vs. Ex-Term subjects (200+/-5 ms, df = 68, F = 18.8, p < 0.001). PVT lapses were increased in Ex-Preterm subjects, and varied inversely with P50 amplitude (Overall Mean 17+/-5 lapses, df = 67, F = 5.34, p < 0.05; Low P50 amplitude, 25+/-10, df = 40, F = 8.8, p < 0.01; Medium, 21+/-11, df = 38, F = 5.37, p < 0.05; High, 6+/-2, df = 39, F = 6.78, p < 0.01) vs. Ex-Term subjects (2+/-0.4 lapses, p < 0.01). NIRS levels did not differ statistically, but tended to correlate with P50 amplitude in the Ex-Preterm group. CONCLUSIONS: These findings suggest differential pre-attentional, attentional and frontal lobe dysfunction in Ex-Preterm adolescents. SIGNIFICANCE: These measures could provide a means to objectively assess differential dysregulation of arousal and attention in Ex-Preterm adolescents, allowing optimization of therapeutic designs.     

Awareness and knowledge about risks of drinking during pregnancy in pregnant Lebanese women

Objective

To assess the awareness and knowledge of pregnant Lebanese women about the risks of drinking during pregnancy and the factors that influence their drinking patterns.

Materials and methods

A prospective study was conducted on a sample of 107 women consulting the gynecology outpatient department of Hôtel-Dieu de France in Beirut, Lebanon, who completed the T-ACE screening test included in a 21 multiple choice questionnaire which examine knowledge and beliefs about alcohol use during pregnancy, drinking patterns and awareness of fetal alcohol exposure.

Results

The 107 women of our sample were all married, between 20 and 41 years old and had mostly a high educational level (86%). Most of the women (47%) were at their first pregnancy. Of the 20 women who self-reported drinking during pregnancy, 60% obtained a positive score on the T-ACE questionnaire, which indicates that more than 11% of the women engaged with potentially high risk drinking for the baby. There is not a significant difference between the different age categories or educational levels. This proportion is lower than that found in international publications. However, the rate of excessive drinking (4 drinks or more on any one occasion in females) was higher and one woman in five reported excessive drinking in the previous year. There is a high level of knowledge that alcohol use during pregnancy is harmful to the child, and the more consumption the more harmful and likely the effects, but there is confusion about the safety of small amounts of alcohol. Women (37%) think that there is a safe level of drinking during pregnancy; 29% tolerate up to one drink a month, 9% tolerate up to one drink a week and one woman thinks having one drink a day is safe. Women who actually drink during pregnancy are more likely to think that alcohol consumption to a certain level is safe. Women (31%) think that beer and/or wine are safe alcohols to a certain level during pregnancy. When asked about the source of this belief, 22% mention a gynecologist but the majority (61%) says it is a personal belief. Women (65%) in our sample are aware that alcohol use during pregnancy can lead to life-long disabilities in a child, such as delayed development (36%), birth defects/deformities (35%) and mental retardation (32%). However, up to 33% of the respondents report having no information about the effects of alcohol on the fetus and two women believe alcohol is not harmful at all. Women with lower levels of education are somewhat less knowledgeable about the risks of alcohol use during pregnancy than those with higher levels of education. There is no association between the drinking patterns of the women with their age, their professional habits and the alcohol consumption of their husbands. The women in our sample seem to be more aware of the necessity to stop smoking rather than stop drinking during pregnancy.

Conclusion

Lebanese women are not fully aware of the recommendations and risks related to drinking during pregnancy. This is the reason why action must be taken to ensure better diffusion of these recommendations and better assessment of alcohol intake during prenatal visits.     

Randomized trials stopped early for benefit: a systematic review

Context  Randomized clinical trials (RCTs) that stop earlier than planned because of apparent benefit often receive great attention and affect clinical practice. Their prevalence, the magnitude and plausibility of their treatment effects, and the extent to which they report information about how investigators decided to stop early are, however, unknown. Objective  To evaluate the epidemiology and reporting quality of RCTs involving interventions stopped early for benefit. Data Sources  Systematic review up to November 2004 of MEDLINE, EMBASE, Current Contents, and full-text journal content databases to identify RCTs stopped early for benefit. Study Selection  Randomized clinical trials of any intervention reported as having stopped early because of results favoring the intervention. There were no exclusion criteria. Data Extraction  Twelve reviewers working independently and in duplicate abstracted data on content area and type of intervention tested, reporting of funding, type of end point driving study termination, treatment effect, length of follow-up, estimated sample size and total sample studied, role of a data and safety monitoring board in stopping the study, number of interim analyses planned and conducted, and existence and type of monitoring methods, statistical boundaries, and adjustment procedures for interim analyses and early stopping. Data Synthesis  Of 143 RCTs stopped early for benefit, the majority (92) were published in 5 high-impact medical journals. Typically, these were industry-funded drug trials in cardiology, cancer, and human immunodeficiency virus/AIDS. The proportion of all RCTs published in high-impact journals that were stopped early for benefit increased from 0.5% in 1990-1994 to 1.2% in 2000-2004 (P<.001 for trend). On average, RCTs recruited 63% (SD, 25%) of the planned sample and stopped after a median of 13 (interquartile range [IQR], 3-25) months of follow-up, 1 interim analysis, and when a median of 66 (IQR, 23-195) patients had experienced the end point driving study termination (event). The median risk ratio among truncated RCTs was 0.53 (IQR, 0.28-0.66). One hundred thirty-five (94%) of the 143 RCTs did not report at least 1 of the following: the planned sample size (n = 28), the interim analysis after which the trial was stopped (n = 45), whether a stopping rule informed the decision (n = 48), or an adjusted analysis accounting for interim monitoring and truncation (n = 129). Trials with fewer events yielded greater treatment effects (odds ratio, 28; 95% confidence interval, 11-73). Conclusions  RCTs stopped early for benefit are becoming more common, often fail to adequately report relevant information about the decision to stop early, and show implausibly large treatment effects, particularly when the number of events is small. These findings suggest clinicians should view the results of such trials with skepticism.      

Anesthetic considerations in steroid-induced mediastinal lipomatosis

Mediastinal lipomatosis (ML) is a benign condition characterized by circumscribed overgrowth of adipose tissue producing mediastinal widening that can cause errors in diagnosis on chest roentgenogram. We describe a case of steroid-induced ML leading to difficulty in central venous catheterization during surgery and its other implications for anesthesiologists. Because many patients receive long-term steroid administration and present for surgical intervention, it is essential that they undergo detailed preoperative evaluation to exclude Cushing's syndrome and various pressure effects. IMPLICATIONS: This case report highlights problems during right internal jugular vein cannulation resulting from high back pressure and flow from superior vena cava obstruction in steroid-induced mediastinal lipomatosis. Other anesthetic considerations in mediastinal lipomatosis are also discussed.