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The COVID-19 pandemic has significantly affected health care delivery globally. COVID-19 is associated with varied neurological manifestations including acute ischemic stroke. In densely populated South Asian nations like Nepal that have suboptimal baseline health care systems, we foresee unique challenges during this pandemic to ensure effective stroke management as well as the safety of health care workers involved in the management of stroke patients. Keywords: COVID-19; health care workers; safety; stroke management.

Objectives: The main objective of this study is to identify the prevalence of hearing loss in school aged children of Nepal., Methods: This cross-sectional study was carried out on school aged children attending the government run schools of Nepal. A total of 79,340 children from grades 1 through 10 were included in the study. After taking brief history about ear diseases and hearing loss, children were screened for ear diseases in their respective classroom by otoscope. Hearing evaluation was carried out by pure tone audiometer and hearing threshold was obtained at 0.5-4 kHz. The results were then documented and analyzed., Results: The prevalence of hearing impairment in school aged children in Nepal is found to be 5.73% (4551 of 79,340). Conductive hearing loss was the most common type of hearing loss and was observed in 70.47% (n = 3207) of the children., Conclusions: This study shows that hearing loss is a common problem in children of Nepal. With the main cause of hearing loss due to preventable conditions such as chronic otitis media, it is believed that early standardized screening, detection and timely management of chronic otitis media in these children can prevent hearing loss and its impact on their educational, social and language development. School based ear health programs are a useful community-oriented solution for prevention of deafness. It shows how important it is to introduce hearing screening for primary school aged children to prevent hearing loss., (Copyright © 2021 Elsevier B.V. All rights reserved.)

The presence of wax is a common finding during ear examination of children and it is one of the main causes of avoidable hearing impairment in children. The objective of this study was to find out the prevalence of wax in ear and evaluate the hearing loss in school-aged children. This is a cross sectional school-based study conducted over a four-year period. Children aged 5-16 were examined by otoscope and pure tone hearing thresholds were obtained at 0.5, 1, 2, and 4 kHz frequencies. A total of 53,970 children from 312 schools of Kathmandu valley were screened. The prevalence of ear wax was 34.64% (n=18697) and hearing impairment associated with wax was 0.88% (n=475). Ear wax and associated hearing loss is a common problem in Nepalese children. Lack of trained personnel and the costs involved in its treatment makes ear wax a big challenge for Nepal's rudimentary health care system., Competing Interests: None

Scientific research can act as the 'bedrock for development' which can provide a solid foundation for the overall socioeconomic transformation in a country through invention and innovation. The inclusion of seven groups of Nepalese monuments in the United Nations Educational, Scientific and Cultural Organization (UNESCO)'s world heritage sites provides evidence of the richness in architecture and civil engineering in the country, which also show how Nepal was influenced by arts and religious philosophy. The government of Nepal (GoN) has established different scientific departments, universities, and research institutions, and has tried to emphasize the application of science and research for the development of the nation. These institutions, however, have inadequate resources, exist in a poor academic and research environment and are subject to overt political influence. Despite these various problems, a variety of pioneer research and development activities have been conducted, which show positive rays of hope. This review presents history, current situation, progress and future perspective for scientific research and development in Nepal., Competing Interests: The authors declare no conflict of interest., (© 2020 The Authors.)

Posterior fossa arteriovenous malformations represent 7-15% of all intracranial AVMs. They carry a higher risk of rupture than supratentorial AVMs and are associated with considerable rates of morbidity and mortality. Available treatment options include conservative management, microsurgical resection, radiosurgery, endovascular embolization, or combinations of these modalities. Recent advances in endovascular techniques have revolutionized their management with better clinical outcomes. We illustrate two cases of posterior fossa AVMs treated by endovascular techniques with good clinical outcomes. The first patient also had associated flow-related aneurysms. One of these aneurysms had already ruptured, so it was coiled first followed by AVM nidus embolization using the same microcatheter. The second patient had a diffuse type of posterior fossa AVM for which staged-embolization was planned and the first-stage partial embolization was successfully performed.

Objectives: The main objective of the study was to ascertain the prevalence of chronic otitis media and determine the corresponding hearing loss in children from Nepal's Himalayan region now residing in Buddhist Monastic schools of Nepal., Methods: The study was conducted among children at Buddhist monastic school in different parts of Nepal. A total of 3174 children aged between 5 and 15 years, who were originally from the Himalayan region of Nepal and were currently residing in monastic schools, were screened for ear problems and hearing loss. They were examined by otoscope to diagnose chronic otitis media. Hearing was evaluated by pure tone audiometer, and 0.5-4 kHz air conduction hearing threshold was measured and documented., Results: Of the total of 3174 children who were screened for ear diseases and hearing loss, monks constituted 76.21% (n = 2419) and Nuns 23.78% (n = 755). Chronic otitis media was the most common otoscopic finding during the screening, and it affected a total of 344 (10.83%) children. Out of these 344, hearing loss of varying degrees was observed in 5.42% (n = 172) children., Conclusion: There is high prevalence of chronic otitis media in children belonging to the Himalayan region of Nepal, and it is the main cause of avoidable hearing loss. Timely diagnosis and treatment of chronic otitis media could prevent unnecessary hearing loss in these children., Competing Interests: None., (© 2020 PLA General Hospital Department of Otolaryngology Head and Neck Surgery. Production and hosting by Elsevier (Singapore) Pte Ltd.)

Giant intracranial aneurysms are defined as aneurysms that measure over 25 mm in the greatest dimension. They are rare vascular lesions that preferentially involve regions with high-velocity blood flow, such as the cavernous and supraclinoid segments of the internal carotid artery, the middle cerebral artery, the vertebrobasilar region, and the basilar apex. The treatment of giant aneurysms is challenging and associated with high rates of morbidity and mortality. Flow-diverter devices have revolutionized their treatment in recent times. We report the successful management of two patients with giant cavernous internal carotid artery aneurysms using flow-diverter devices for the first time in Nepal. Keywords: Endovascular; flow-diverter devices; giant aneurysm.

Mechanical stimuli have profound effects on the cellular architecture and functions. Over the past two decades, considerable progress has been made in unraveling the molecular machineries that confer cells the ability to sense and transduce mechanical input into biochemical signals. This has resulted in the identification of several force-sensing proteins or mechanically activated ion channels distributed throughout most cell types, whereby the plasma membrane, cytoskeleton, and the nucleus have garnered much attention. Although organelles from the endomembrane system make up significant portion of cell volume and play pivotal roles in the spatiotemporal distribution of signaling molecules, they have received surprisingly little attention in mechanobiology. In this mini-review, we summarize results that document participation of the endomembrane system in sensing and responding to mechanical cues., (Copyright © 2020 Phuyal and Baschieri.)

While studies of the autophagy-related (ATG) genes in knockout models have led to an explosion of knowledge about the functions of autophagy components, the exact roles of LC3 and GABARAP family proteins (human ATG8 equivalents) are still poorly understood. A major drawback in understanding their roles is that the available interactome data has largely been acquired using overexpression systems. To overcome these limitations, we employed CRISPR/Cas9-based genome-editing to generate a panel of cells in which human ATG8 genes were tagged at their natural chromosomal locations with an N-terminal affinity epitope. This cellular resource was employed to map endogenous GABARAPL2 protein complexes using interaction proteomics. This approach identified the ER-associated protein and lipid droplet (LD) biogenesis factor ACSL3 as a stabilizing GABARAPL2-binding partner. GABARAPL2 bound ACSL3 in a manner dependent on its LC3-interacting regions, whose binding site in GABARAPL2 was required to recruit the latter to the ER. Through this interaction, the UFM1-activating enzyme UBA5 became anchored at the ER. Furthermore, ACSL3 depletion and LD induction affected the abundance of several ufmylation components and ER-phagy. Together these data allow us to define ACSL3 as a novel regulator of the enigmatic UFM1 conjugation pathway., Competing Interests: Competing interestsThe authors declare no competing or financial interests., (© 2020. Published by The Company of Biologists Ltd.)

PPR is an economically important trans-boundary disease of sheep and goats. Nepal had experienced several episodes of PPR outbreaks in the past. Although severity and frequency of outbreaks have decreased due to strenuous effort of Government of Nepal, it has been rather endemic. National PPR Control Program 2001, and PPR Control Program Implementation Working Guidelines, 2013, the legal documents guiding PPR control activities, have not been effective as expected due to multifactorial reasons. Thus, a critical analysis of the program with emphasis on impeding factors is must. In this review, we attempted to analyse and suggest more effective strategies considering geopolitical, social and cultural context of Nepal., Competing Interests: Conflict of interestI/We hereby declare that there is no conflict of interest regarding the technical and financial aspects of this research., (© Indian Virological Society 2020.)

Avian influenza virus infection in humans is an emerging zoonotic disease having high economic and public health impacts. Due to its capability for genetic re-assortment, this virus can emerge as novel influenza strains with pandemic potential. Even though the first Avian influenza incidence in humans in Nepal was reported in April 2019, the threat of the disease remains unmitigated. Limited resources for surveillance, disease tracking, and weak health care facilities in low and middle-income countries will increase the possibility of the outbreak. Therefore, timely management and preparedness by strengthening veterinary and medical services, operational capabilities of laboratories, and surveillance programs through the "One-Health" approach could be crucial for the control of possible outbreaks in Nepal., Competing Interests: Conflict of interestThere are no competing interests., (© Indian Virological Society 2020.)

More than 75% of emerging infectious diseases and 60% of known human infectious diseases are transmitted from animals. Among these zoonoses, rabies is of utmost public health significance due to its lethality. The multi-faceted nature of zoonotic disease complicates control and prevention and thus, a multi-sectoral One Health Approach could be a better strategy to cope with rabies. Up until now, rabies prevention and control programs are conducted utilizing mass vaccination of domestic and community dogs and cats, and mass awareness programs. However, the burden of rabies has not been reduced as these approaches have failed to include all stakeholders (human, animal, and environmental health sectors) in disease management programs. The aim of this review is to highlight why and how One Health Approach would be the most effective way to control rabies in low- and middle-income countries (LMICs) like Nepal., Competing Interests: There are no competing interests., (© 2020 The Authors.)

Viruses are having great time as they seem to have bogged humans down. Severe acute respiratory syndrome (SARS), Middle East respiratory syndrome (MERS), and novel coronavirus (COVID-19) are the three major coronaviruses of present-day global human and animal health concern. COVID-19 caused by SARS-CoV-2 is identified as the newest disease, presumably of bat origin. Different theories on the evolution of viruses are in circulation, yet there is no denying the fact that the animal source is the skeleton. The whole world is witnessing the terror of the COVID-19 pandemic that is following the same path of SARS and MERS, and seems to be more severe. In addition to humans, several species of animals are reported to have been infected with these life-threatening viruses. The possible routes of transmission and their zoonotic potentialities are the subjects of intense research. This review article aims to overview the link of all these three deadly coronaviruses among animals along with their phylogenic evolution and cross-species transmission. This is essential since animals as pets or food are said to pose some risk, and their better understanding is a must in order to prepare a possible plan for future havoc in both human and animal health. Although COVID-19 is causing a human health hazard globally, its reporting in animals are limited compared to SARS and MERS. Non-human primates and carnivores are most susceptible to SARS-coronavirus and SARS-CoV-2, respectively, whereas the dromedary camel is susceptible to MERS-coronavirus. Phylogenetically, the trio viruses are reported to have originated from bats and have special capacity to undergo mutation and genomic recombination in order to infect humans through its reservoir or replication host. However, it is difficult to analyze how the genomic pattern of coronaviruses occurs. Thus, increased possibility of new virus-variants infecting humans and animals in the upcoming days seems to be the biggest challenge for the future of the world. One health approach is portrayed as our best way ahead, and understanding the animal dimension will go a long way in formulating such preparedness plans., Competing Interests: The authors declare that there is no conflict of interest.

Posterior circulation strokes are potentially devastating events that carry a significant risk of morbidity and mortality. Acute basilar artery occlusion stroke is a rare posterior circulation stroke that needs emergent management. We report the case of a 67-year-old woman who developed an acute basilar artery occlusion. We achieved complete recanalization of the occluded basilar artery and its branches with endovascular mechanical thrombectomy. It is possible to achieve excellent results with mechanical thrombectomy in acute basilar artery occlusion if timely diagnosis and reperfusion can be done. We are not aware of any previous publication from Nepal describing this technique in acute basilar artery occlusion.

Imperforate hymen, though a congenital anomaly, usually presents late in puberty as lower abdominal pain, primary amenorrhea, and cyclical pain. Blood collects in vagina and uterus, proximal to imperforate hymen leading to their distention. Its presentation at infancy is a rare entity. We report such a rare case of symptomatic imperforate hymen in infancy, who presented with acute retention of urine, chills and rigor. Abdominal examination revealed an intra-abdominal mass in the lower abdomen and pelvis with the absence of vaginal opening on perineal examination. Contrast enhanced computed tomography abdomen showed large abdominopelvic cystic lesion posterior to the urinary bladder and anterior to the rectum consistent with a highly distended vagina. She was managed by the incision of the imperforate hymen and drainage of the pus. A high index of suspicion is necessary whenever a female infant presents with abdomino-pelvic mass with symptoms of fever or urinary retention.

Obstructed by hurdles in information extraction, handling and processing, computer-assisted sperm analysis systems have typically not considered in detail the complex flagellar waveforms of spermatozoa, despite their defining role in cell motility. Recent developments in imaging techniques and data processing have produced significantly improved methods of waveform digitization. Here, we use these improvements to demonstrate that near-complete flagellar capture is realizable on the scale of hundreds of cells, and, further, that meaningful statistical comparisons of flagellar waveforms may be readily performed with widely available tools. Representing the advent of high-fidelity computer-assisted beat-pattern analysis, we show how such a statistical approach can distinguish between samples using complex flagellar beating patterns rather than crude summary statistics. Dimensionality-reduction techniques applied to entire samples also reveal qualitatively distinct components of the beat, and a novel data-driven methodology for the generation of representative synthetic waveform data is proposed., Competing Interests: We declare we have no competing interest., (© 2020 The Authors.)

Intradural spinal epidermoid cysts are rare, benign lesions either acquired from trauma, surgery, lumbar puncture or arise as congenital lesions, particularly associated with spinal dysraphism. Epidermoid cyst arising from the spine with expansile destruction of vertebrae has not been reported yet in the literature. We report a case of 36-years male presented with history of fall 8 years back with progressive symptoms of lower back pain, weakness of left lower limb and bladder/bowel incontinence. Computed tomography revealed large lytic expansile, midline sacral vertebral lesion with soft tissue component and multiple calcific foci. Magnetic resonance imaging demonstrated large non-enhancing heterogeneous mass showing restricted diffusion on diffusion weighted images. The patient underwent biopsy confirming the diagnosis of an epidermoid cyst. The possibility of an epidermoid tumor should be kept in the differential diagnosis in patients presenting with post-traumatic sacral mass.

The Rho family of small GTPases orchestrates fundamental biological processes such as cell cycle progression, cell migration, and actin cytoskeleton dynamics, and their aberrant signaling is linked to numerous human diseases and disorders. Traditionally, active Rho GTPase proteins were proposed to reside and function predominantly at the plasma membrane. While this view still holds true, it is emerging that active pool of multiple Rho GTPases are in part localized to endomembranes such as endosomes and the Golgi. In this review, we will focus on the intracellular pools and discuss how their local activation contributes to the shaping of various cellular processes. Our main focus will be on Rho signaling from the endosomes, Golgi, mitochondria and nucleus and how they regulate multiple cellular events such as receptor trafficking, cell proliferation and differentiation, cell migration and polarity.

The original article [1] contains errors in author panels and their contributions, errors in both the Methodology and the Results sections, and errors with respect to funding sources. The affected sections of the manuscript and their respective regions of corrected text can be viewed ahead.

Background: Avian pathogenic Escherichia coli (APEC) are causative agent of extraintestinal infections, collectively known as colibacillosis, which results significant losses in poultry industries. The extraintestinal survival of E. coli is facilitated by numerous virulence factors which are coded by virulence genes. This study was conducted to find out the pattern of antibiotic resistance and virulence genes content in the APEC strains isolated from broiler chickens at National Avian Disease Investigation Laboratory and Veterinary Teaching Hospital, Rampur, Chitwan, Nepal., Results: A total of 50 E. coli strains were isolated from 50 colibacillosis suspected broiler chickens. Out of 50 isolates of E. coli, 47 (94%) showed resistant to three or more antimicrobials. The highest levels (22%) of multidrug-resistant E. coli were observed for five different types of antimicrobials. Antibiogram profiles of 50 E. coli strains showed the maximum resistance to ampicillin (98%), followed by co-trimoxazole (90%), and doxycycline (62%). The highest intermediate resistance was shown by colistin (50%) and the highest sensitivity was against amikacin (84%), followed by nitrofurantoin (55%). Based on the genetic criteria, 45 (90%) E. coli isolates were considered as pathogenic (APEC) which contained more than five virulence genes. Out of total APEC genes detected, we found the combination of iss, iucD, hlyF, ompT, iroN, and iutA genes were mostly associated with the APEC and additionally, to some lesser extent irp2, papC, Cva/cvi, and tsh genes showed the critical role for virulent traits of APEC strains., Conclusion: In this study, high prevalent of antimicrobial resistant pattern was found with avian pathogenic E. coli strains isolated from broiler chickens. To our knowledge, this is the first molecular analysis which confirmed the prevalence of APEC strains in poultry sector in Nepal. These finding suggest the need of surveillance and intervention system to control misuse of antibiotics and APEC outbreak in the poultry farm.

The effects of long-term chronic exposure of human lung cells to multi-walled carbon nanotubes (MWCNT) and their impact upon cellular proteins and lipids were investigated. Since the lung is the major target organ, an in vitro normal bronchial epithelial cell line model was used. Additionally, to better mimic exposure to manufactured nanomaterials at occupational settings, cells were continuously exposed to two non-toxic and low doses of a MWCNT for 13-weeks. MWCNT-treatment increased ROS levels in cells without increasing oxidative DNA damage and resulted in differential expression of multiple anti- and pro-apoptotic proteins. The proteomic analysis of the MWCNT-exposed cells showed that among more than 5000 identified proteins; more than 200 were differentially expressed in the treated cells. Functional analyses revealed association of these differentially regulated proteins to cellular processes such as cell death and survival, cellular assembly, and organization. Similarly, shotgun lipidomic profiling revealed accumulation of multiple lipid classes. Our results indicate that long-term MWCNT-exposure of human normal lung cells at occupationally relevant low-doses may alter both the proteome and the lipidome profiles of the target epithelial cells in the lung.

The most plausible exposure route to manufactured nanomaterials (MNM) remains pulmonary inhalation. Yet, few studies have attempted to assess carcinogenic properties in vitro following long-term exposure of human pulmonary cells to low and occupationally relevant doses. The most advanced in vitro tests for carcinogenicity, the cell transformation assay (CTA), rely mostly on rodent cells and short-term exposure. We hypothesized that long-term exposure of human bronchial epithelial cells with a normal phenotype could be a valuable assay for testing carcinogenicity of nanomaterials. Therefore, this study (performed within the framework of the FP7-NANoREG project) assessed carcinogenic potential of chronic exposure (up to 6months) to low doses of multi-walled carbon nanotubes (MWCNT, NM-400 and NM-401) and TiO 2 materials (NM62002 and KC7000). In order to harmonize and standardize the experiments, standard operating protocols of MNM dispersion (NANOGENOTOX) were used by three different NANoREG project partners. All nanomaterials showed low cytotoxicity in short-term tests for the tested doses (0.96 and 1.92μg/cm 2 ). During long-term exposure, however, NM-401 clearly affected cell proliferation. In contrast, no cell transformation was observed for NM-401 by any of the partners. NM-400 and NM62002 formed some colonies after 3months. We conclude that agglomerated NM-401 in low doses affect cell proliferation but do not cause cell transformation in the CTA assay used., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Current methods for characterisation of extracellular vesicles (EVs) need further standardisation in order to obtain an acceptable level of data comparability. Size and concentration of EVs can be determined by nanoparticle tracking analysis (NTA). However, both the heterogeneity of EVs and the choice of instrument settings may cause an appreciable analytical variation. Intra-assay (within-day, n  = 6) and inter-assay (day-to-day, n  = 6) variations (coefficient of variation, % CV) of different preparations of EVs and artificial vesicles or beads were determined using two NanoSight NS500 instruments, located at different laboratories. All analyses were performed by the same operator. The effect of applying identical software settings or instrument-optimised settings for each sample type and instrument was also evaluated. Finally, the impact of different operators and the use of two different software versions were investigated. The intra-assay CVs were 1-12% for both EVs and artificial samples, measured on the same instrument. The overall day-to-day variation was similar for both instruments, ranging from 2% to 25%. However, significantly different results were observed between the two instruments using identical software settings. The effect of applying instrument-optimised settings reduced the mismatch between the instruments, resulting in little to no significant divergences. The impact of using different operators and software versions when analysing silica microspheres and microvesicles from monocytes using instrument-optimised settings on the same instrument did not contribute to significant variation compared to the overall day-to-day variation of one operator. Performance differences between two similar NTA instruments may display significant divergences in size and concentration measurements when analysing EVs, depending on applied instrument settings and technical conditions. The importance of developing a streamlined and standardised execution of analysis, as well as monitoring longitudinal variation parameters on both biological and synthetic samples, should be highlighted.

Background: Previous findings have demonstrated that lumbar radicular pain after disc herniation may be associated with up-regulation of inflammatory mediators. In the present study we examined the possible role of extracellular microRNAs (miRs) in this process., Methods: Single unit recordings, isolation of exosome-like vesicles, electron microscopy, nanoparticle tracking analysis, western blot analysis and qPCR were used in rats to demonstrate the effect of nucleus pulposus (NP) applied onto the dorsal nerve roots. ELISA and qPCR were used to measure the level of circulating IL-6 and miRs in a 1-year observational study in patients after disc herniation., Results: In the rats, enhanced spinal cord nociceptive responses were displayed after NP applied onto the dorsal nerve roots. An increased release of small non-coding RNAs, including miR-223, miR-760 and miR-145, from NP in exosome-like vesicles was demonstrated. In particular, the NP expression of miR-223, which inhibited the nociceptive spinal signalling, was increased. In the patients, increased extracellular miR-223 was also verified in the acute phase after disc herniation. The increased miR-223 expression was, however, only observed in those who recovered (sex, age and smoking were included as covariates)., Conclusions: Our findings suggest that miR-223, which can be released from the NP after disc herniation, attenuates the neuronal activity in the pain pathways. Dysregulation of miR-223 may predict chronic lumbar radicular pain. Trial registration/ethics REK 2014/1725.

Introduction: Total calcium (TC) and albumin-corrected calcium (ACC) are easily accessible AP severity tests in the Primary Health Care Center of Nepal. The aim of the study was to evaluate TC and ACC as prognostic severity markers in acute pancreatitis (AP)., Methods: All patients admitted in Tribhuvan University Teaching Hospital with the diagnosis of AP were studied prospectively over a period of one year from January 2015 to January 2016. TC and ACC were measured in the first 24 hours of admission in each patient. The modified Marshall score was determined at admission and at 48 hours and at any point of time during admission as per the need of the patient. Severity of acute pancreatitis was defined as per the Revised Atlanta Classification 2012., Results: 80 patients of AP were included in the study. Among them, 14% were categorized as having severe AP. The mean total calcium was 8.22, 7.51, and 6.98 for mild, moderate, and severe AP, respectively, which was significant at 0.001., Conclusion: TC and ACC, measured within the first 24 hours, are useful severity predictors in acute pancreatitis.

The aim of the study was to correlate the high-resolution computed tomography (HRCT) finding of high-attenuation mucus (HAM) impaction, including mean CT density and immunologic parameters in patients with allergic bronchopulmonary aspergillosis (ABPA). The institutional review board approved the study, and informed written consent was obtained. A total of 100 consecutive patients diagnosed with ABPA between June 2012 and December 2013 undergoing HRCT were enrolled. HRCT scan of the chest was evaluated for central bronchiectasis, mucoid impaction, and number of involved bronchial segments. Findings of mucoid impaction in patients were classified as HAM and non-HAM. CT attenuation values and mean CT density were calculated. Serologic parameters were assessed for total immunoglobin E (IgE), specific IgE, and absolute eosinophil count. Patients with HAM impaction on HRCT were found to have significantly higher levels of total IgE (P < 0.001), specific IgE (P = 0.03), and number of bronchial segments affected (P < 0.001). We found a CT density value of 70 Hounsfield units (HU) as an adequate cutoff value for HAM impaction. CT density >100HU is correlated with significantly higher values of serologic parameters. The present study suggests a relation between absolute HU values of HAM impaction and absolute value of serologic parameters in ABPA., (Copyright © 2015 Mosby, Inc. All rights reserved.)

Exosomes are vesicles released by cells after fusion of multivesicular bodies with the plasma membrane. In this study, we have investigated whether ether lipids affect the release of exosomes in PC-3 cells. To increase the cellular levels of ether lipids, the ether lipid precursor hexadecylglycerol was added to cells. Lipidomic analysis showed that this compound was in fact able to double the cellular levels of ether lipids in these cells. Furthermore, increased levels of ether lipids were also found in exosomes released by cells containing high levels of these lipids. Interestingly, as measured by nanoparticle tracking analysis, cells containing high levels of ether lipids released more exosomes than control cells, and these exosomes were similar in size to control exosomes. Moreover, silver staining and Western blot analyses showed that the protein composition of exosomes released in the presence of hexadecylglycerol was changed; the levels of some proteins were increased, and the levels of others were reduced. In conclusion, this study clearly shows that an increase in cellular ether lipids is associated with changes in the release and composition of exosomes., (© 2015 by The American Society for Biochemistry and Molecular Biology, Inc.)

Exosomes are released by cells after fusion of multivesicular bodies with the plasma membrane. The molecular mechanism of this process is still unclear. We investigated the role of sphingolipids and flotillins, which constitute a raft-associated family of proteins, in the release of exosomes. Interestingly, our results show that dl-threo-1-phenyl-2-decanoylamino-3-morpholino-1-propanol, an inhibitor of glucosylceramide synthase, seemed to affect the composition of exosomes released from PC-3 cells. However, the inhibition of ceramide formation from the de novo pathway by fumonisin B1 did not affect exosome secretion. Moreover, in contrast to findings obtained with other cell lines published so far, inhibition of neutral sphingomyelinase 2, an enzyme that catalyzes the formation of ceramide from sphingomyelin, did not inhibit the secretion of exosomes in PC-3 cells. Finally, small interfering RNA-mediated downregulation of flotillin-1 and flotillin-2 did not significantly change the levels of released exosomes as such, but seemed to affect the composition of exosomes. In conclusion, our results reveal the involvement of glycosphingolipids and flotillins in the release of exosomes from PC-3 cells, and indicate that the role of ceramide in exosome formation may be cell-dependent., (© 2014 FEBS.)

Exosomes are small extracellular vesicles released to the extracellular milieu through fusion of multivesicular bodies with the plasma membrane. These vesicles contain microRNAs and might therefore be vehicles transferring genetic information between cells. The aim of this study was to investigate whether there was a sorting of microRNAs into exosomes in the prostate cancer cell line PC-3. In addition, microRNAs in PC-3 cells and in the non-cancerous prostate cell line RWPE-1 were compared. Exosomes were isolated from the conditioned media from PC-3 cells by ultracentrifugation and inspected by electron microscopy. Total RNA was isolated and microRNAs were analyzed by microarray analysis and real time RT-PCR. MicroRNA microarray analysis revealed that the microRNA profile of PC-3 released exosomes was similar to the profile of the corresponding parent cells. Nevertheless, a sorting of certain microRNAs into exosomes was observed, and low number microRNAs (microRNAs with a low number in their name) were found to be underrepresented in these vesicles. Moreover, the miRNA profile of PC-3 cells resembled the miRNA profile of RWPE-1 cells, though some miRNAs were found to be differently expressed in these cell lines. These results show that exosomes from PC-3 cells, in agreement with previous reports from other cell types, contain microRNAs. Furthermore, this study supports the idea that there is a sorting of microRNAs into exosomes and adds a new perspective by pointing at the underrepresentation of low number miRNAs in PC-3 released exosomes., (Copyright © 2012 Elsevier B.V. All rights reserved.)