Discover and publish cutting edge, open research.

Browse 8,699 multi-disciplinary research preprints

Most recent

Danielle Davenport

and 5 more

Population size is a central parameter for conservation, however monitoring abundance is often problematic for threatened marine species. Despite substantial investment in research, many marine species remain data-poor resulting in uncertain population forecasts and restricting the evaluation of past and present conservation actions. Such is the case for the white shark (Carcharodon carcharias), a highly mobile apex predator for whom population monitoring is a conservation priority following substantial declines recorded through the 20th century. Here, we estimate the effective number of breeders that successfully contribute offspring in one reproductive cycle (Nb) providing a snapshot of recent reproductive effort in an east-Australian New Zealand population of white shark. Nb was estimated over four consecutive age cohorts (2010, 2011, 2012, 2013) using two genetic estimators (linkage-disequilibrium; LD and sibship assignment; SA) based on genetic data derived from two types of genetic markers (single-nucleotide-polymorphisms; SNPs and microsatellite loci). While estimates of Nb using different marker types produced comparable estimates, microsatellite loci were the least precise. The LD and SA estimates of Nb within cohorts using SNPs were comparable, for example the 2013 age-cohort Nb(SA) was 289 (95%CI 200-461) and Nb(LD) was 208.5 (95%CI 116.4-712.7). We show that over the time period studied Nb was stable and ranged between 206.1(±45.9) and 252.0(±46.7) per year using a combined estimate of Nb(SA+LD) from SNP loci, and a simulation approach showed that in this population effective population size (Ne) per generation can be expected to be larger than Nb per reproductive cycle. This study demonstrates how breeding population size can be monitored over time to provide insight into the effectiveness of recovery and conservation measures for the white shark, where the methods described here may be applicable to other data-poor species of conservation concern.

Denglang Zou

and 5 more

1. Toxin resistance in all taxa is important for their survival. Resistance to bufadienolide toxin is mediated by molecular changes to the sodium-potassium-pump. As for toads themselves, the parotid is consisted of extremely high concentration of bufadienolide toxin, it indicates toads need stronger resistance for self-protection than any other species involved in toad predation. Thus, besides the widespread convergence of Na+/K+-ATPase, toads may develop a unique self-resistance way for their accumulated bufadienolide toxin. 2. Our studies on invasive cane toads from Australia and common asiatic toads from China showed that toads store defensive venom in parotid as a combinatorial library composed of low-toxic protoxin (conjugated bufadienolides), which is characterized by two building blocks, i.e. high-toxic toxin (free bufadienolide) and the argininyl side chain contributed to toxin absorption promotion. This protoxin could be hydrolyzed to high-toxic toxin for defense immediately as it is discharged from parotid at the time when toad is attacked or stimulated by predators. 3. Our results revealed that toads indeed develop a unique protoxin self-resistance way to their own extremely high concentration of bufadienolide toxin for self-protection besides the widespread convergence of Na+/K+-ATPase. The revelation of this protoxin self-resistance way highlights the importance and ecological multifunctionality of the sophisticated combinatorial chemistry of nature and may partly account for the strong adaptability of toad as infamous ailing invaders. It completes the picture of self-resistance mechanism to their own bufadienolide toxin for toad or may even for many other venomous animals.

Dominic Moyo

and 4 more

Abstract: Background. Doxorubicin chemotherapy drug , use is limited by it’s potential to cause cardiotoxicity. In resource poor settings, like Malawi, monitoring of doxorubicin cardiotoxicity is not routinely conducted in cancer patients and the incidence of doxorubicin cardiotoxicity is not known. Methods. Children aged 3 months to 18 years with cancer were prospectively enrolled from the paediatric oncology ward and followed up from January 2016 to June 2019. Transthoracic echocardiographic monitoring of left ventricular ejection fraction (LVEF) was done at baseline, one month, six months and a year after completion of therapy. Cardiotoxicity was defined as a decline in LVEF of ≥10% to a final value of <50%, and an overall incidence risk of developing cardiotoxicity was estimated. A one-way analysis of variance was conducted to compare baseline LVEF with that measured during follow up intervals. Findings. A total of 91 children were enrolled into the study, 74% (68/91) were male, and 67% (62/91) were aged 5 months to 14 years. Burkitt lymphoma was diagnosed in 41% (38/91) of the children. No one experienced cardiotoxicity during the study period. However, of 77 children who had at least one follow up, five children 6·54% (95% CI: 2.1-14.5) experienced a reduction in LVEF of >10%, though not to a final value of <50%. No deterioration of systolic function was found among 20 children who had completed follow up. (F= 2·43, p-value=0·07). Interpretation. In this cohort, there were no observed cardiotoxic events associated with doxorubicin administration as per pre-defined criterion

Latifa Adarmouch

and 3 more

Introduction: The aim of this study was to assess the impact of the COVID-19 pandemic on the activity of private medical practices in Morocco. Methods: An online survey was carried out in June 2020. The study population consisted of physicians (General practitioners and specialists) who run private practices in different regions of Morocco. The questionnaire comprised 3 sections: demographic and professional data, the impact noticed by the doctors and the strategies adopted to tackle this impact. Results: We analyzed 225 responses. Specialists represented 71.6% of the respondents. The majority (94.2%) of the private practices were located in urban areas. Almost all respondents have noticed a change in the demand for medical services, mainly a decrease (96,44%). There was an increase in urgent consultations (30.7%) and consultations for acute motives (39.1%). Respondents also reported less (69,3%) or no (23,1%) regular follow-up visits for patients with chronic diseases. Decreased incomes concerned 97,33% of the practices. Doctors reacted by working less hours (87,55%), delaying some procedures (78,22%), and applying recommended safety measures (100%). Telemedicine was used in an informal way to facilitate the communication with patients. Discussion and conclusion: During this pandemic, private practices were challenged to contribute to the continuity of healthcare services while ensuring the safety of the staff and the patients. Several strategies were adopted to cope with the new situation and to survive its many challenges.

Browse more recent preprints

Recently published in scholarly journals

Wahaj Munir

and 3 more

Background: Acute type A aortic dissection (ATAAD), is a surgical emergency often requiring intervention on the aortic root. There is much controversy regarding root management; aggressively pursuing a root replacement, versus more conservative approaches to preserve native structures. Methods: Electronic database search we performed through PubMed, Embase, SCOPUS, google scholar and Cochrane identifying studies that reported on outcomes of surgical repair of ATAAD through either root preservation or replacement. The identified articles focused on short- and long-term mortalities, and rates of re-operation on the aortic root. Results: There remains controversy on replacing or preserving aortic root in ATAAD. Current evidence supports practice of both trends following an extensive decision-making framework, with conflicting series suggesting favourable results with both procedures as the approach that best defines higher survival rates and lower perioperative complications. Yet, the decision to perform either approach remains surgeon decision and bound to the extent of the dissection and tear entries in strong correlation with status of the aortic valve and involvement of coronaries in the dissection. Conclusions: There exists much controversy regarding fate of the aortic root in ATAAD. There are conflicting studies for impact of root replacement on mortality, whilst some study’s report no significant results at all. There is strong evidence regarding risk of re-operation being greater when root is not replaced. Majority of these studies are limited by the single centred, retrospective nature of these small sample sized cohorts, further hindered by potential of treatment bias.

Matthew Sussman

and 9 more

The recognition of fibrinolysis phenotypes in trauma patients has led to a reevaluation of antifibrinolytic therapy (AF). Many cardiac patients also receive AF, however the distribution of fibrinolytic phenotypes in that population is unknown. The purpose of this study was to fill that gap. Methods: Data were retrospectively reviewed from 78 cardiac surgery patients. Phenotypes were defined as hypofibrinolytic (LY30 <0.8%), physiologic (LY30 0.8-3.0%) and hyperfibrinolytic (LY30 >3%). Continuous variables were expressed as M ± SD or median (interquartile range). Results: The study population was 65±10 yrs old, 74% male, average body mass index of 29±5 kg/m2. Fibrinolytic phenotypes were distributed as physiologic=45%, hypo=32% and hyper = 23%. There was no obvious effect of age, gender, race, or ethnicity on the distribution of fibrinolysis phenotypes; 47% received AF. The time with chest tube during post-operative recovery was longer in those who received AF (4[3,5] days) vs no AF (3[2,4] days), P=0.037). All cause morbidity occurred in 51% of patients who received AF vs 25% with no AF (p=0.017). However, with AF vs no AF, apparent differences in median chest tube output (1379 vs 820ml, p=0.075), hospital LOS (13 vs 10 days, P=0.873), estimated blood loss (1100 vs 775 ml, P=0.127), units of transfused RBCs (4 vs 2], P=0.152) or all-cause mortality (5.4% [2/37] vs 10% [4/41], P=0.518) were not statistically significant. Conclusion: This is the first description of three distinctly different fibrinolytic phenotypes in cardiac surgery patients. In this population, the use of AF was associated with increased morbidity.

Arushi Singh

and 6 more

Background: Ibrutinib is associated with atrial fibrillation (AF), though echocardiographic predictors of AF have not been studied in this population. We sought to determine whether left atrial (LA) strain on transthoracic echocardiography could identify patients at risk for developing ibrutinib-related atrial fibrillation (IRAF). Methods: We performed a retrospective review of 66 patients who had an echocardiogram prior to ibrutinib treatment. LA strain was measured with TOMTEC Imaging Systems, obtaining peak atrial longitudinal strain (PALS) and peak atrial contraction strain (PACS) on 4-chamber and 2-chamber views. Statistical analysis was performed with Chi-square analysis, T-test, or binomial regression analysis, with a p-value < 0.05 considered statistically significant. Results: Twenty-two patients developed IRAF (33%). Age at initiation of ibrutinib was significantly associated with IRAF (65.1 years vs. 74.1 years, p = 0.002). Mean ibrutinib dose was lower among patients who developed IRAF (388.2 ± 121.7 vs. 448.6 ± 88.4, p = 0.025). E/e’ was significantly higher among patients who developed IRAF (11.5 vs. 9.3, p = 0.04). PALS was significantly lower in patients who developed AF (30.3% vs. 36.3%, p = 0.01). On multivariate regression analysis, age, PALS and PACS were significantly associated with IRAF. On multivariate regression analysis, only PACS remained significantly associated with IRAF while accounting for age. Conclusions: Age, ibrutinib dose, E/e’, and PALS on pre-treatment echocardiogram were significantly associated with development of IRAF. On multivariate regression analyses, age, PALS and PACS remained significantly associated with IRAF. Impaired LA mechanics add to the assessment of patients at risk for IRAF

James Hummel

and 1 more

We thank Medina et al. for their interest in our recent work on QTc prolongation associated with treatment of COVID-19 patients with hydroxychloroquine and azithromycin. As they appropriately point out in their letter, genetic variation is likely a significant determinant of QT prolongation in the population at large and in COVID-19 patients specifically. While drugs causing acquired long QT syndrome and torsades de pointes are generally blockers of IKr, repolarization results from the aggregate of multiple inward and outward currents. Patients with sub-clinical defects in any of these ion channels can have normal or only slightly prolonged baseline QT intervals, but may possess decreased repolarization reserve leading to an exaggerated response to IKr blockade (1).  In our study, a baseline QTc of > 460 ms was associated with excessive QTc prolongation, and this likely represents a group of patients with sub-clinical cardiac ion channel mutations (so called “first hit”) (2). We also agree that many patients with latent mutations demonstrate a normal baseline QT, which gets prolonged with the addition of a drug or a change in the clinical condition “second hit” (3). The patients in our study who exhibited QTc prolongation were generally acutely ill, and displayed “multiple hits” that led to QTc prolongation and it is certainly plausible that many may have had sub-clinical cardiac ion mutations. We therefore wholeheartedly agree that pharmacogenetics should be considered in studies of drug-induced QT prolongation, however this information is rarely available to include for acutely ill patients. And while it makes sense to obtain genetic profiles prior to administration of QT-prolonging medications, that can only be performed in the elective outpatient setting, while taking into consideration medical, ethical and social issues related to asymptomatic genetic screening (e.g. cost, reimbursement, informed consent, etc…). There is significant interest in building genomic databases, and when this becomes a reality for the population at large we believe that genetic information should certainly be included in studies of QT prolongation.Roden DM Long QT syndrome: reduced repolarization reserve and the genetic link. J Intern Med. 2006 Jan; 259(1):59-69.Napolitano C, Schwartz PJ, Brown AM, et al. Evidence for a cardiac ion channel mutation underlying drug-induced QT prolongation and life-threatening arrhythmias. J Cardiovasc Electrophysiol. 2000;11:691–6Sauer AJ and Newton-Cheh C. Clinical and genetic determinants of torsade de pointes risk. Circulation. 2012;125:1684-94.

Norman Mukarati

and 10 more

Numerous unknown factors influence anthrax epidemiology in multi-host systems, especially at wildlife/livestock/human interfaces. Serology tests for anti-anthrax antibodies in carnivores are useful tools in identifying the presence or absence of Bacillus anthracis in a range. These were employed to ascertain if the disease pattern followed the recognized high and low risk anthrax zonation in Zimbabwe and also to establish if anthrax was absent from Hwange National Park in which there has been no reported outbreaks. African lions (Panthera leo) (n= 114) drawn from -free-range protected areas and captive game parks located in recognized high and low risk zones across Zimbabwe were tested for antibodies to anthrax PA antigen using the ELISA immunoassay. A random selection of 27 lion sera samples comprising 17 sero-positive and 10 sero-negative sera were further tested in the species-independent toxin neutralization assay (TNA) in order to validate the former as a surveillance tool for anthrax in African lions. Using the ELISA-PA immunoassay, 21.9% (25/114) of the lions tested positive for antibodies to anthrax. Seropositivity was recorded in all study areas and there was no significant difference (p= 0.852) in seropositivity between lions in high and low risk anthrax zones. Also, there was no significant difference (McNemar’s χ2 = 0.9, p = 0.343) in the proportion of lions testing positive to anti-PA anthrax antibodies on ELISA-PA immunoassay compared to the TNA, with fair agreement between the two tests [Kappa (K) statistic = 0.30; 0.08

Roberto CHIESA

and 3 more

During the first phase of COVID-19 pandemic in Italy, several strategies have been taken to deal with the pandemic outbreak. The Regional Authority of Lombardy remodeled the hospitalization system in order to allocate appropriate resources to treat COVID-19 patients and to identify “Hub/Spoke” hospitals for highly specialized medical activities. The Hubs hospitals were required to guarantee full time evaluation of all patients presenting with cardiovavascular diseases with an independent pathway for patients with suspect or confirmed COVID-19 infection. San Raffaele Hospital was identified as Hub for cardiovascular emergencies and the Vascular Surgery Department was remodeled to face this epidemic situation. Surgical treatment was reserved only to symptomatic, urgent or emergent cases. Large areas of the hospital were simultaneously reorganized to assist COVID-19 patients. During this period, 135 patients were referred to San Raffaele Vascular Surgery Department. COVID-19 was diagnosed in 24 patients and, among them, acute limb ischemia was the most common cause of admission. At this time, the COVID-19 trend is in decline in Italy and the local authorities reorganized the health care system in order to return to normal activities avoiding new escalations of COVID-19 cases. Several strategies have been taken to ensure the safety of the San Raffaele hospital, and maintaining potentially suspected patients with COVID-19 separated from other patients. The aim of this paper is to report the remodeling of the Vascular Surgery Department of San Raffaele Hospital as regards the strategies of preparation, escalation, de-escalation and return to normal activities during the COVID-19 pandemic.

Browse more published preprints

How it works

Upload or create your research work
You can upload Word, PDF, LaTeX as well as data, code, Jupyter Notebooks, videos, and figures. Or start a document from scratch.
Disseminate your research rapidly
Post your work as a preprint. A Digital Object Identifier (DOI) makes your research citeable and discoverable immediately.
Get published in a refereed journal
Track the status of your paper as it goes through peer review. When published, it automatically links to the publisher version.
Learn More
Featured collections
Explore More Collections

Other benefits of Authorea


A repository for any field of research, from Anthropology to Zoology


Discuss your preprints with your collaborators and the scientific community

Interactive Figures

Not just PDFs. You can publish d3.js and graphs, data, code, Jupyter notebooks

Featured templates
Featured and interactive
Journals with direct submission
Explore All Templates