P = 0.017)—or 3%—many of these additional mail ballots counted only because a last-minute policy intervention allowed most mail ballots postmarked by Election Day to count.The ability to cast a mail ballot can safeguard the franchise. However, because there are often additional procedural protections to ensure that a ballot cast in person counts, voting by mail can also jeopardize people’s ability to cast a recorded vote. An experiment carried out during the COVID-19 pandemic illustrates both forces. Philadelphia officials randomly sent 46,960 Philadelphia registrants postcards encouraging them to apply to vote by mail in the lead-up to the June 2020 primary election. While the intervention increased the likelihood a registrant cast a mail ballot by 0.4 percentage points ( The United States has long used absentee voting to protect the voting rights of people who find it difficult to vote at a polling place, such as military personnel and citizens with disabilities . ElectioWhile increased access to mail ballots has helped protect voting rights, there are also concerns that their increased use could disenfranchise voters , 6. A maTo better understand how access to mail balloting affected Americans’ ability to vote during the pandemic, we analyze a field experiment conducted in Philadelphia leading up to Pennsylvania’s 2 June 2020 primary election. Philadelphia had a stay-at-home order in place from 23 March until after the primary. Two weeks before the election, 46,960 randomly selected registrants received postcards with information about applying to vote by mail. This was the first statewide federal election held since Pennsylvania adopted universal access to mail ballots, so information about how to apply was particularly likely to increase awareness of voting by mail.Previous field experiments show that facilitating mail ballot requests increases their use. Refs. P = 0.004), and about 0.4 percentage points more likely to return a mail ballot (P = 0.017), than registrants who did not. Roughly half of the additional mail ballots cast by registrants sent postcards were received after Election Day. While Pennsylvania state law specifies that mail ballots must be received by Election Day, issues with mail ballot distribution and large-scale protests following George Floyd’s death led Pennsylvania’s governor to order that ballots postmarked by Election Day be counted if received within a week of Election Day. While such estimates are noisy, the changes in in-person voting and overall turnout jointly suggest that 35% of the increased voting by mail came from substitution by people who would have otherwise voted in person.Our results show that registrants receiving a postcard about mail balloting were at least as likely to successfully cast a ballot in the 2020 primary as those that did not, but that this occurred partly because of a late change in policy. Registrants receiving the postcard were about 0.5 percentage points more likely to request a mail ballot (We seek to answer three research questions. We are primarily interested in 1) whether postcards from local officials increase applications to vote by mail and secondarily 2) whether the postcards’ wording matters or 3) their effect is stronger among those who had received four postcards as part of a prior 2019 experiment. The University of Pennsylvania Institutional Review Board approved this study (832927).The universe for this experiment consists of 935,745 registered voters. This represents a subset of the 1,048,575 registered voters in the universe for a previous mobilization experiment conducted by the City of Philadelphia and the City Commissioners prior to the 2019 municipal election.Registrants in our experimental universe were sent one of two postcards about mail ballots or no postcard. The postcards conveyed information about the 26 May deadline to request a mail ballot and included a message either encouraging voters to request a ballot because “[i]t’s safer for you to vote by mail!” or “[i]t’s safer for [neighborhood] to vote by mail!”t tests to confirm that there were no significant imbalances in any of the 78 covariates used in the blocking, including subjects’ ward of residence, party registration, or prior vote history.We used a stratified, blocked randomization to determine who received postcards. We blocked on several variables that were measured before treatments were administered in the initial 2019 experiment as well as whether a registrant received postcards in the initial experiment.Mail ballots were sent only to those requesting them by the 26 May deadline. Mail ballots originally had to be received by the primary, but a last-minute policy change allowed ballots to be counted if they were postmarked by 2 June if received by 9 June.SI Appendix provides additional information about our outcomes, which include whether subjects requested a mail ballot, failed to return a mail ballot, voted by mail, voted in person, or cast a provisional ballot, as well as when mail ballots were received.Top) and whose ballot was received (Bottom). As expected, there was no difference in either applications received or mail ballots received before the postcards were mailed. However, those assigned to receive postcards subsequently applied for mail ballots and returned those ballots at higher rates.In received , Bottom.t tests comparing those receiving a postcard to those not. The first column provides the full-sample results. Those assigned to treatment were 0.5 percentage points more likely to apply for a mail ballot (P = 0.004) and 0.4 percentage points more likely to vote by mail (P = 0.017). They were 0.2 percentage points more likely to have their ballot received after the primary and for it to be recorded (P = 0.01 for both). There was no significant impact on in-person voting (P = 0.462). While turnout overall was up 0.2 percentage points in the treated group, this difference is insignificant (P = 0.259). Together, the treatment group’s (insignificant) 0.13 percentage point decrease in in-person voting coupled with its (significant) 0.37 percentage point increase in mail voting suggest that roughly 35% (0.13/0.37) of the increased mail voting comes from substitution by people who would have otherwise voted in person.How large are such differences? The results are essentially identical when reestimated via linear models conditioning on the variables included in the blocking.P = 0.005). The effect of substitution from in-person voting remains similar, too.In columns 2 through 4 of In Philadelphia’s June primary, encouraging voting by mail increased recorded votes by mail. Under certain conditions, mail ballots can certainly increase the use of the franchise. However, the procedures for counting mail ballots condition their ability to enfranchise. Mail ballots are at greater risk than ballots cast in person to be not counted because of clerical errors or procedural violations. For example, in Pennsylvania’s November 2020 election, thousands of mail ballots were not counted because they were not enclosed in secrecy envelopes, a provision not enforced in the primary. Also, it is plausible that primary voters were more knowledgeable about vote-by-mail options and that a similar information campaign in a highly salient general election could produce larger effects. In such conditions, political parties may well intervene to assist voters in navigating this process, too.In the run-up to the 2020 elections, officials made substantial efforts through multiple media to educate voters about voting by mail. Our results provide an estimate of the impact of one such effort and may inform future efforts.Supplementary File


Currently, it is an ongoing challenge to develop fluorescent nanosphere detectors that are uniform, non-toxic, stable and bearing a large number of functional groups on the surface for further applications in a variety of fields. Here, we have synthesized hairy nanospheres (HNs) with different particle sizes and a content range of carboxyl groups from 4 mmol/g to 9 mmol/g. Based on this, hairy fluorescent nanospheres (HFNs) were prepared by the traditional coupling method (TCM) or adsorption-induced coupling method (ACM). By comparison, it was found that high brightness HFNs are fabricated based on HNs with poly (acrylic acid) brushes on the surface via ACM. The fluorescence intensity of hairy fluorescent nanospheres could be controlled by tuning the content of 5-aminofluorescein (5-AF) or the carboxyl groups of HNs easily. The carboxyl content of the HFNs could be as high as 8 mmol/g for further applications. The obtained HFNs are used for the detection of heavy metal ions in environmental pollution. Among various other metal ions, the response to Cu (II) is more obvious. We demonstrated that HFNs can serve as a selective probe and for the separation and determination of Cu(II) ions with a linear range of 0–0.5 μM and a low detection limit of 64 nM. Heavy metal ion determination and removal are becoming more and more important. Copper (Cu(II)), a crucial cofactor for multiple enzymes, plays an critical role in bone formation together with certain proteins ,2, but iOver the last decade, many analytical approaches for Cu(II) ions quantification have been noted according to the detection methods, such as atomic absorption spectroscopy (AAS) , colorimFluorescent nanospheres (FNs) that can excite fluorescence under the stimulation of external energy have become of interest in many fields, particularly in ion detection ,13,14,15Hairy nanospheres (HNs) based on polymer brush structure, typically spherical poly (acrylic acid) brushes ,30, haveIn this paper, we report an effective method for fabricating hairy fluorescent nanospheres (HFNs) using hairy nanospheres (HNs). The HFNs were well characterized and the fluorescence intensity was controlled and optimized. The method presented here can be considered as a general method to other fluorescent molecules with functional groups. The extra carboxyl groups of HFNs can be used in further applications like enzyme immobilization, antibody coupling etc. Here, HFNs with abundant extra carboxyl groups could be used as the detector for Cu(II).N-hydroxy-succinimide (NHS), potassium persulfate (KPS), hydrochloric acid (HCl), sodium hydroxide (NaOH), sodium dodecyl sulfate (SDS), 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC) and 2-(N-morpholino) ethanesulfonic acid (MES) were bought from Adamas-beta . 5-Aminofluorescein (5-AF) was obtained from Aladdin . Sodium hydrogen phosphate and sodium dihydrogen phosphate were obtained from sinopharm .Styrene (St) and acrylic acid (AA) were purchased from Aladdin  and reserved to use after distillation under reduced pressure. Phosphate buffer  and 2-(N-morpholino) ethanesulfonic acid buffer  were formulated before the coupling experiments.Narrowly distributed hairy nanospheres (HNs) were prepared by the combination of conventional emulsion polymerization and photoemulsion polymerization according to our previous work ,33,34. FTypically, for the traditional coupling methods (TCM), 10 mg of hairy nanospheres (HNs) were added into 10 mL buffer , then 80 mg NHS and 120 mg EDC were dispersed into the buffer. The mixture was incubated for 15 min under shaking at room temperature. 5-AF, ranging from 0.5 wt.% to 4 wt.%, was dispersed into 10 mL PBS buffer (pH = 7.2), then HNs after activation of carboxyl were quickly added into the solution containing 5-AF under sonication. The solution was allowed to react for 10 h under gentle shaking at room temperature. The HFNs were purified by dialysis using pure water until the conductivity was no longer changed. For the adsorption-induced coupling methods (ACM), the 10 mg HNs were dissolved in buffer  and 5-AF, ranging from 0.5 wt.% to 16 wt.%, was added. The mixture was subjected to physical adsorption for 2 h at room temperature and then coupled with 80 mg EDC on a shaker for 10 h to obtain narrowly dispersed hairy fluorescent nanospheres (HFNs). After the coupling was completed, the HFNs were purified by dialysis using pure water until the conductivity was no longer changed. The hydrodynamic diameter of particles was measured by dynamic light scattering (DLS NANO-S90). Intensity-average size and polydispersity index (PDI) were obtained for analysis.Fluorescence images of HFNs was obtain by laser confocal microscope calorimetry .Morphology of particles were characterized by scanning electronic microscopy (SEM), the voltage of the instrument is about 5 kV.The carboxyl content of the polyelectrolyte brush was calculated by conductivity instrument (METTLER-T50). The titrant is NaOH and its concentration is 0.1 mol/L.The fluorescence intensity of all HFNs were measured by the constant wavelength synchronous fluorescence method (Spectrofluorometer FS5). In our study, we chose a constant-wavelength (Δλ) equal to the Stokes shift .10 particles mL−1 of FHNs at most). The probability of HFNs as a fluorescent detector for metal ions was investigated at a normal temperature. Some metal ions solutions, including Cr(III), Cu(II), Cd(II), Ca(II), Mg(II), Pb(II), Ni(II) and Ag(I),were mixed with FHNs respectively with same concentrations  accurately, metal ions with different concentrations were mixed with HFNs at room temperature (the concentration of HFNs was kept at 2 × 1010 particles mL−1).The quantity of HFNs in aqueous solution can be calculated from the formula (1) .The quaAfter shaking for 3 min at normal temperature, fluorescent signals were recorded by using the synchronous fluorescence method (Spectrofluorometer FS5). As shown in the In this work, hairy nanospheres and polystyrene-poly (acrylic acid) (PS-PAA) were selected as a carrier. The core of HNs used here is 157 nm, and the thickness of the PAA chain is 57 nm. The amino of 5-AF and carboxyl of HNs can be fixed together by typical NHS/EDC coupling. However, the process may greatly sacrifice the potential of the PAA brushes due to the special three-dimensional structure of the HNs. Therefore, two methods for preparing HFNs were designed, i.e., the traditional coupling method (TCM) and adsorption-induced coupling method (ACM). The proposed mechanism for TCM is described in However, in the adsorption-induced coupling method (ACM), both the HNs and the 5-AF were dispersed in the MES buffer; therefore, it was easier for 5-AF to enter the inside of the HNs and carry on electrostatic adsorption owing to the unique electrostatic adsorption of the polyelectrolyte brushes ,42,43. TTo confirm the speculation, the two coupling methods were carried out and compared. As a start, the traditional coupling method (TCM) was employed to introduce 5-AF into the monodisperse HNs bearing poly(acrylic acid) (PAA) shell with thickness of 57 nm.The concentration of the 5-AF was firstly set to 0.5 wt.%, which is a typical dye content in fluorescent nanospheres obtained by other methods ,48, as sWe then changed to an alternative coupling process  adsorptb. The seFluorescein is connected to the carboxyl in the HNs. Therefore, the fluorescein immobilization amount is closely related to the carboxyl content, so the effect of carboxyl content on fluorescence intensity was explored in the further study. HNs with different PAA thickness were used and their characteristic parameters are shown in C is the concentration of the titrant (HCl), V2 and V1 are the volumes consumed by sodium hydroxide, which are the turning points at the low conductivity after the addition of the NaOH and m is the amount of added HNs (g).The carboxyl content of the HNs is calculated according to formula (2).The conductometric titration curves of HNs with various PAA thickness was shown in The fluorescence intensity of the HFNs also depends on the dye content. A high content of 5-AF coupled to the carboxyl groups may lead to fluorescence quenching, which is adverse to obtaining a cost-effective use of 5-AF. We studied the relationship between the 5-AF dosage and fluorescence intensity of the HFNs. The core of HNs used here is 77 nm and the thickness of PAA chain is 139 nm. As shown in As shown in The saturated reaction amount of carboxyl groups is 3 mmol/g, which is near one-third of the total carboxyl groups. When the 5-AF dosage continues to increase from 8 wt.% to 16 wt.%, the fluorescence intensity sharply decreased, which is most likely as the result of the fluorescence aggregation quenching effect. The spacing between the fluorescent molecules reaches the critical point of fluorescence quenching due to the further increase of 5-AF. When the PAA thickness is 139 nm with the 8 wt.% 5-AF, the highest fluorescence brightness HFNs can be obtained.We then calculated that up to two-thirds of the carboxyl groups were still free after adequate coupling of 5-AF, which could be used as the functional groups in applications including ion detection and removal.F0 − F)/F0 was found to be linear with respect to the concentration of Cu (II) . Therefore, HFNs can be used as a sensitive fluorescence detector for detecting the concentration of Cu(II). There is a good linear relationship between the fluorescence enhancement of Cu(II) loaded HFNs (HFNs@Cu(II)) and the concentration of S(-II) . The recovery of HFNs from HFNs@Cu(II) could be realized by further adding sulfide anion S(-II) [In this work, HFNs (HN5 with 8 wt.% 5-AF) were selected as a detector to detect Cu(II). The fluorescence intensity of HFNs versus the concentration of Cu(II)   into then S(-II)  at a cosThe detection performance of HFNs was good compared to other reported results concerning the fluorescence sensors for the detecting of Cu(II) or S(-II) as shown in Various metal ions ,52 were In summary, a new adsorption-induced coupling method (ACM) for the preparation of fluorescent nanospheres has been developed. The ACM makes full use of the abundant carboxyl groups, which means that it is efficient, simple and easy to control the fluorescence intensity of HFNs. When the PAA thickness is 50 nm, the fluorescence intensity of HFNs obtained by the adsorption-induced coupling method (ACM) is 200% of the traditional coupling method (TCM). The thicker the PAA, the higher the carboxyl content, and the higher fluorescence intensity at the same 5-AF dosage. For HNs with the same PAA thickness, 5-AF dosage could be higher, up to 8 wt.%, without obvious fluorescence quenching, which is almost one magnitude higher than that produced by other routes. HFNs with abundant extra carboxyl groups could be used as detectors for Cu(II). Extra carboxyl groups on the surface of HFNs can also be used for further applications, and the method proposed here can be considered as a general method for other fluorescent molecules with functional groups. By adjusting the 5-AF content and the PAA thickness, fluorescent-coded beads can be formed for biological analysis. At the same time, HFNs provide useful guidance for understanding the principles of fluorescence tuning and designing novel fluorescent nanospheres in the fields of labeling, detection and biosensing.


The article examines how many leaders used Twitter during the COVID-19 pandemic, in what way, and the impact they had on the public. In the context of Twitter, the impact on the public refers to the growth in followers as it signifies the increased interest of the public about information. 50,872 tweets were collected from 143 state leaders and an original dataset was created containing information on the growth of followers. Ordinary least squares regression models were used for the analysis. It was found that 64.8% of UN member states had a leader that tweeted about COVID-19. Furthermore, a significant increase in the number of followers during the pandemic compared to months prior was noted. Since March, the pandemic has been a dominant topic on Twitter. During the COVID-19 pandemic, the highest percentage increase in gaining Twitter followers was experienced by politicians who frequently tweeted and those who had a lower ratio of the number of followers to internet users. The research implies that citizens are interested in being informed about emergencies through social networks, and government officials should use them. Social sciences; Social media; Twitter; COVID-19; Uses and gratifications theory; Public communication; Political communication. COVID-19 is transmitted quite effectively and is primarily spread by contact transmission and respiratory droplets . State lSeveral mass communication theories are used and applied to social media . One of In recent years, research on political communication through Twitter has become more prominent in social science research , 2016. TNumerous studies have been published that examined spreading misinformation on social media during the COVID-19 pandemic . For exaHowever, there has been only one study that examined state leaders and their activity on Twitter and this was limited to the world leaders of the Group of Seven (G7). The study shows, alongside other findings, that world leaders of the G7 all use Twitter except Angela Merkel . It may This article is unique because a study has not yet been presented that analyzes the global use of Twitter by state leaders and the public's reaction to it. Therefore, it is a significant contribution to the literature that examines the situation during the COVID-19 pandemic. The article is divided into four main parts. The first part offers information on the methods used and has two subsections. The first subsection concerns with data collection and the second subsection explains regression models. The second part presents the results with two subsections. The first subsection offers insights from social media analytics while the second subsection shows insights from regression models. Therefore, the first subsection presents mainly figures and tables about the usage of Twitter during the pandemic by state leaders. Thus, it is focused on the visual presentation of the activity of world leaders. In the second section, the explanation about the growth rate of Twitter followers on leaders' accounts is offered. Regression models were used to determine the reasons for the growth rate of Twitter followers. The third part discusses contribution to theory and literature, implications to practice, limitations and suggests avenues for future research. In the last part, the core findings are mentioned.2In recent years, big data research and their challenges have been the subject of literature . This st2.1Twitter API was used to create the original dataset of state leaders' tweets. 50,872 tweets that were sent from 30 December 20192.2The dependent variable is the growth of Twitter followers in percentage points from 27 January to 3 May 2020. This period was chosen because it covers the outbreak of COVID-19 and the spread of confirmed cases around the world. At the beginning of May 2020, almost every country had already put some measures in place to curb the spread of COVID-19. Moreover, at that time, every state leader analyzed in this study had already tweeted about the pandemic, as As it has been already mentioned, detailed information about the growth rate of Twitter followers for all state leaders was not for the purpose of study available. Furthermore, state leaders that took office in January 2020 and later were filtered out because it would skew results as one would expect there to be an increase of Twitter followers based on their win. Also, leaders who did not mention COVID-19 on Twitter were filtered out. Therefore, in the regression models, 113 leaders from UN member states were included. There may be various reasons that explain the growth of Twitter followers. Four predictor variables were chosen.The first independent variable is the number of tweetsOne may assume that the world leaders with greater Twitter activity gain more followers than leaders who use Twitter very little. State leaders with a very high number of followers are limited in the possibility of the growth of Twitter followers. Therefore, this possibility was measured for growth in the following way: number of followers as of 27 January 2020/number of users of internet in the country x 100. Here, the ratio of the number of followers to internet users was calculated as a percentage. Data on internet usage in a country was provided by the Another important factor in the usage of Twitter is the language that is used. Users tweeting in English may attract more attention. Therefore, it is possible that leaders tweeting in global languages can have an advantage in also gaining followers from other countries. This may be particularly in the case of neighboring countries with the same language. Citizens follow foreign leaders to see how the virus might have spread in neighboring countries but also world leaders that use global language. Therefore, four languages were chosen that might have a significant impact on the boosting of followers. These were English, Spanish, French, and Arabic. Therefore, the fourth variable, language, is a categorical variable. All other languages used by world leaders were included in the group “other languages”. Even though there were languages that are widely spoken in the group “other languages,” they were used only by a few leaders33.1The first insight from social media analytics concerns with the first mention of COVID-19 on Twitter. It is important to examine when the state leaders first mentioned COVID-19 on Twitter. To do this, several keywords, such as “COVID,” “corona,” “virus”, were looked for within the accounts of leaders. However, many leaders use a non-Latin script. Therefore, the words coronavirus and virus were translated into all languages. After that, tweets found corresponded with COVID-19 were manually re-checked. Leaders, by mentioning COVID-19 on Twitter, acknowledge it as a significant threat. However, not all leaders use Twitter in the same fashion. While leaders who frequently use Twitter might have informed people about the danger of COVID-19 when the disease remained mostly in China and a few other countries, others waited until they started putting security measures in place in their own countries before they informed citizens. Therefore, how swift people were informed about COVID-19 might differ significantly. Table 1The second insight from social media analytics relates to what words leaders used. While it is possible to express the content of tweets by certain groups on Twitter in different ways, one of the most effective ways is to visualize it as word clouds. It is a commonly used technique in social media analytics . This haThird insight from social media analytics concerns with how often state leaders tweeted. The fourth insight from social media analytics relates to the growth of Twitter followers. First, the number of tweets sent by state leaders was analyzed. Second, the number of followers that state leaders gained on Twitter was examined. One may assume that these matters are connected. Therefore, the next section analyzes them in regression models. However, this section describes and visualizes them. The growth rate and frequency of tweeting were not equal, and there are significant differences between state leaders. Moreover, there are two vertical lines. The blue dashed line indicates the first case of COVID-19 in a country, while the dotted orange line denotes the first mention of COVID-19 on Twitter by a particular leader. These two lines are important to visualize as one may expect that the growth rate would start after the first mention of COVID-19 and the first confirmed case in a country. Each graph starts with the first week of January (30 December 2019) and the last week ends on 3 May 2020. Therefore, it covers a period of a little over four months. The weeks of January can be considered as a baseline for growth. It is possible to see that there is a sharp increase in the growth rate for all presented leaders in February and especially March. In April, the growth rate declines as the room for growth was partially exhausted. It is more likely that citizens would start following their leaders in February and especially March as the pandemic started to significantly spread. As graphs clearly show, European politicians such as Giuseppe Conte and Boris Johnson even gained around 15% of followers within one week. Similar growth was also experienced by Latin American leaders Iván Duque and Alberto Fernández. Emmanuel Macron and Pedro Sánchez had a lower increase that could have been caused by an already significant number of followers. Interestingly, in the case of Cyril Ramaphosa, the growth rate continued to increase until April. This may be because South Africa, unlike European countries, experienced a significant spread in COVID-19 later. Donald Trump had a higher growth rate at the beginning of the year in the middle of impeachment than later during the COVID-19 pandemic.3.2Descriptive statistics are presented in The number of cases per one million people has a negative association with the dependent variable and does not reach statistical significance in the model. One might consider this surprising. However, even countries with a small number of cases have introduced strict measures to prevent the spread of COVID-19. Therefore, the need for information from state leaders may be similar for citizens from countries with a low and high number of cases. The last variable was language. Models show that when country leaders used French their growth rate increased significantly in comparison to the reference group (“other languages”). Many neighboring African countries use French as their main language, and, therefore, there was a possibility to follow various leaders in the region. All other global languages also have a positive direction, and English and Spanish also reach statistical significance. However, their coefficients are lower compared to French.44.1This paper contributes to the significant body of literature examining the COVID-19 pandemic. The study showed that the global pandemic COVID-19 significantly impacted the discourse on Twitter accounts of state leaders. It was the most important topic at that time. Twitter is an important tool for state leaders as it allows them to easily communicate directly with their citizens. They recognize this importance. Therefore, it is not a surprise that most governments have an active presence on social media . FindingThese findings correspond to the UGT  that staThe finding on the growth of followers offers some contrast to the literature on spreading misinformation during the COVID-19 pandemic . It is i4.2There are some clear implications to practice from this study. During times of crisis, political actors and relevant authorities should offer relevant information through different media. Twitter, as a social media website, is a relatively new medium compared to traditional television or radio. At the moment, not all state leaders use Twitter. However, this study shows that state leaders who tweeted more frequently gained more Twitter followers. Therefore, people will follow state leaders when they offer information to fulfill their needs during health emergencies. Understandably, there are fewer reasons and less motivation to follow rather inactive accounts. In today's digital age, governments should make use of modern technology, such as Twitter, to be transparent on the state of the country and provide relevant health information for their citizens. Recommendation and information from relevant authorities are important for preventing the spread of COVID-19 as a study on U. S. governors' Twitter communications confirms . However4.3The limitation of the study is that it was not feasible to confirm that followers are legitimate accounts of citizens. However, the same limitation also applies to the pre-pandemic period. The study focused only on Twitter follower counts and did not analyze followers. This is understandable as the study would have to analyze the activity of hundreds of millions of Twitter accounts in different time periods. It is very difficult to detect whether accounts are legitimate, especially if accounts are passive and do not tweet.In relation to this study, there is a possibility for future research. It will be especially interesting to see whether politicians retain newly obtained followers or whether users will unfollow them in large numbers when the crisis is over. It is already possible to see that the growth rate is decreasing in comparison to March 2020 in the case of the majority of politicians. However, it does not seem likely that the crisis will be over soon. Therefore, it is possible that there will not be any mass unfollowing soon and that more people will use Twitter.5The study showed that the global pandemic COVID-19 significantly impacted the discourse on Twitter. It was the most important topic at that time. Furthermore, most leaders reacted to the spread of COVID-19. While some mentioned COVID-19 already in January, others mentioned it first in February, March, or April. However, in total, 64.8% of UN member states had a leader that tweeted about COVID-19. Another key finding is that there was a significant growth rate of Twitter followers for state leaders in comparison with pre-pandemic months. Leaders had a higher growth of followers when they used their Twitter accounts more frequently. Therefore, it seems that citizens were interested in the latest update from their leading politicians. Furthermore, especially French-speaking politicians had a higher growth rate compared to leaders speaking other languages and the growth rate was higher when the ratio of the number of followers to internet users was lower as there was room for growth.M. Haman: Conceived and designed the experiments; Performed the experiments; Analyzed and interpreted the data; Contributed reagents, materials, analysis tools or data; Wrote the paper.University of Hradec Králové, Czech Republic.This work was supported by The Philosophical Faculty, Data included in article/supplementary material/referenced in article.The authors declare no conflict of interest.No additional information is available for this paper.


IntroductionThe aim of this study was to evaluate radiological measurements to establish the origin of giant cell tumours of bone.MethodsA multi-centre retrospective review was conducted of patients with histologically confirmed giant cell tumours of bone. Images were analysed to estimate the centre of the tumour. Measured from the joint line, the ratio between the distance of the centre of the tumour and the physeal scar was calculated.ResultsNinety-five patients were included in the study. Two observers found the tumour to be arising from the metaphyseal area in 94% - 97% of the cases. There was good agreement between the measurements of observers (interclass correlation coefficient 0.71).Conclusion Giant cell tumours of bone appear to be arising from the metaphyseal region. Giant cell tumours of bone (GCTBs) are intermediate, locally destructive tumours, accounting for approximately 5% of all primary bone tumours. Typically, young adults between the ages of 20 and 40 years are affected, with a predilection for females . MalignaGiant cell tumours of bone are primarily treated with surgical resection, either by intralesional curettage or wide resection. Intralesional curettage is often favoured, as most giant cell tumours of bone occur peri-articularly and curettage preserves limb function. Some authors favour wide resection to minimise local recurrence. However, these procedures have a higher incidence of surgical complications, including infection, and limited joint function . The manThe aim of this study was to evaluate the origin of giant cell tumours of bone on imaging investigations.PatientsA multi-centre retrospective review was conducted of consecutive adult patients with a confirmed histological diagnosis of a giant cell tumour of bone between June 2012 and May 2017 in two primary bone tumour centres. Inclusion criteria included a confirmed histological diagnosis of a non-malignant giant cell tumour of bone and age over 18 years. Patients without appropriate imaging  were excluded.Magnetic resonance imaging (MRI) imagesMRI images were often obtained from outside institutions and the sequences obtained were not standardised. However, as a minimum, a T1 sequence was obtained in all patients. Measurements were taken from the T1 sequence that had a minimum slice thickness of 3 mm.Images were downloaded from the picture archive and communications system (PACS), duplicated into two separate folders, and measured independently by two observers (A and B). Observer A was a consultant orthopaedic oncologist, and observer B was a medical student. The method of taking measurements Figure  was pre-MeasurementsFrom the MRI images, the distance from the joint line to the physeal scar was measured Figure . The disThe length of the tumour was calculated by subtracting the distance from the joint line to the inferior margin of the tumour Figure  from theA ratio of less than one indicates the tumour originates in the epiphysis and a ratio of greater than one suggests a metaphyseal origin Figure .Statistical analysisData were analysed with R statistical software . Boxplots of ratios were created and agreement between observers was assessed with the interclass correlation coefficient . Bland-AInterclass correlation coefficient values between 0.40 and 0.59 were regarded as showing fair agreement, between 0.60 and 0.74 as good agreement and greater than 0.75 as excellent agreement.Ninety-five patients were identified from a consecutive cohort of 195 patients that had all required imaging available for review. One hundred patients were excluded, as the physeal scar was not visible on images and, therefore, measurements could not be completed. Fifty-six patients were male (59%) and 39 patients were female (41%). The median age was 35 years (interquartile range (IQR): 27 - 47 years). Forty-four (46%) tumours were on the left side and 51 (54%) on the right side. The most common site of tumour was the distal femur in 43 (45%) cases, followed by the proximal tibia in 36 (38%), proximal femur 4 (4%), proximal humerus 4 (4%), metacarpal 3 (3%), distal humerus 1 (1%), distal tibia 1 (1%), proximal fibula 1 (1%), metatarsal 1 (1%) and distal radius 1 (1%).Although roughly spherical, most tumours were slightly longer along the long axis of the bone Figure .The origin of the tumour was found to be predominantly in the metaphyseal area Figure .The interclass correlation coefficient for tumour length over width was 0.56 (95% CI: 0.40 - 0.68) showing only fair agreement between observers. However, the interclass correlation coefficient for the ratio of the tumour centre to the physeal scar was 0.71 (95% CI: 0.60 - 0.80) showing good agreement between observers. The Bland-Altman plot also shows good agreement without bias (Figure Using the ratio as a measure of tumour origin, one observer estimated 97% of the tumours to be metaphyseal in origin whilst the other estimated this to be 94%.Our study suggests that giant cell tumours of bone are tumours originating from the metaphyseal area. It is generally reported in the literature that giant cell tumours of bone are epiphyseal in origin . ConversIn a recent study by Futamura et al., the investigators calculated the vertical centre of tumours on anteroposterior X-rays of tumours . In theiHowever, measurements are not always easy to obtain. Not all patients had appropriate imaging, and of the 195 consecutive patients, only 95 had suitable imaging available. Most patients with a distal radial tumour had extensive involvement, making measurements impossible, as the physeal scar was no longer visible. Our study only includes one patient with a distal radial giant cell tumour of bone and this may have introduced bias.Measurements in the distal femur and proximal tibia were usually straightforward to obtain. However, the physis has a more complex arrangement in the proximal humerus, perhaps explaining the larger variance in measurements in that location.The limited spatial resolution of MRI may have caused further variance in measurements. However, the use of ratios, rather than absolute measurements, helps to reduce this effect.Our results show that the ratio between tumour length and tumour width is roughly equal, indicating a spherical tumour shape. This seems to indicate equal tumour growth in all directions. Consequently, it appears reasonable to assume a metaphyseal origin as indicated by the measurements.Tumour growth is supported by osteoclastic resorption of bone in all directions. However, cartilage cannot be resorbed by the osteoclast and tumour growth stops at the subchondral bone. From then onwards, growth can only occur in the width or proximally. Initially, pain may not be a predominant feature. However, once the tumour has reached the subchondral bone, a subchondral fracture is likely to occur, and the patient presents with pain.Previously, giant cell tumours of bone were considered to be epiphyseal originating tumours. From our study, measurements from MRI images found giant cell tumours of bone to be roughly spherical, but slightly longer in the long axis, and to be originating from the metaphysis in 94%-97% of cases.


Varicella zoster virus (VZV) causes varicella primarily in childhood, and some rare adults also report varicella. Herpes zoster mainly occurs in adults by endogenous reactivation of latent VZV. Until now, varicella and herpes zoster have seldom been reported simultaneously in one patient. Here, we report a rare case co-presenting with varicella and herpes zoster in a Chinese adult.Treponema pallidum infections by ELISA antibody tests. Laboratory tests revealed that the ratio of eosinophils (0.1%) and eosinophil count (0.0 × 109/L) were significantly downregulated. Treatment with valacyclovir, ebastine, mecobalamine, pregabalin and calamine lotion for 5 days was effective therapy for varicella and herpes zoster. Polymerase chain reaction for vesicular fluids from varicella and herpes zoster was positive for VZV, and further phylogenetic analysis and single nucleotide polymorphism variations confirmed that the VZV genotype was type J (clade 2).A 44-year-old Chinese man suffered papules and vesicles with pain on the left ear. Five days after onset, he was admitted to the Department of Dermatology of The Third Hospital of Xiamen. Physical examination revealed that small vesicles surrounded by erythema had developed on his trunk, back and neck, and unilateral papules and vesicles in ribbons had also developed on the left ear. This patient was excluded from human immunodeficiency virus and This rare case highlights awareness of varicella and herpes zoster caused by VZV infection in adults. Our report provides novel insight into the rare clinical presentation of VZV genotype J. Infection with varicella zoster virus (VZV) can cause trivial mucocutaneous lesions to life-threatening neurological syndrome complications, such as postherpetic neuralgia (PHN) and vasculitis . VaricelSingle nucleotide polymorphisms (SNPs) in different open reading frames (ORFs) of the VZV genome have been used for VZV genotyping. Genogroups E (European), M (Mosaic) and J (Japanese) of VZV are further divided into seven clades  based on specific SNPs in ORFs 1, 21, 22, 50 and 54 –13. HereTreponema pallidum were determined, but the patient was negative for these two pathogens. Chest computed tomography confirmed the patient did not have pneumonia. The laboratory test showed that the ratio of neutrophils (82.6%) and neutrophil count (7.8 × 109/L), concentrations of haemoglobin (177 g/L) and complement C4 (0.43 g/L), and haematocrit (51.3%) were upregulated; however, the ratios of lymphocytes (14.3%) and monocytes (2.6%) were downregulated; the ratio of eosinophils (0.1%) and the eosinophil count (0.0 × 109/L) were significantly downregulated  surrounded by erythema had developed on his trunk and back , HSV-2 and VZV were detected by nested PCR , and onlTo examine the genotype of VZV, 6 ORFs  of the VZV genome were amplified  of the VZV genome by PCRAdditional file 3: Supplementary Table S1. Clinical characteristics of a rare case with varicella and herpes zoster in Xiamen, China


In this report, we describe the implementation and short-term outcomes of a Special Populations Consultation Service within the University of California, Los Angeles (UCLA) Clinical and Translational Science Institute (CTSI). With the goal of increasing the quality and quantity of special population (SP) research, the UCLA CTSI Integrating Special Populations program designed a consultation service to support faculty and trainees conducting research involving one of three CTSI “special populations:” children, older adults, and/or minority; underserved; or health disparity populations. The Special Populations Consultation Service offers three types of activities: grant proposal studios, career consultations, and project reviews. UCLA CTSI faculty with appropriate content expertise serve as consultants. We evaluated this consultation model using satisfaction surveys and by quantifying funded grants and reported changes in career goals in SP research. Between 2016 and 2019, the Special Populations Consultation Service provided 59 consultations including 42 grant studios and was used by researchers at all levels from all four UCLA CTSI institutions. Recipients rated the consultations very highly. Funding success rates were 57% following K-level grant studios and 28% following R-level grant studios. Users of project and career consultations commonly attributed career accomplishments in part to their consultation experiences. The SP Consultation Service is feasible and acceptable and appears to enhance careers of investigators studying special populations. The sociodemographic makeup of the United States is rapidly changing. In less than 15 years, non-Latino white persons will become the minority and adults over age 65 years will make up 25% of the American population , while chttps://www.ctsi.ucla.edu/about/programs/pages/specialpop) with support from the University of California, Los Angeles (UCLA) Chancellor’s office and a Clinical and Translational Science Award administered by the National Center for Advancing Translational Sciences (NCATS). The ISP core is within the UCLA Clinical and Translational Science Institute (CTSI) hub, with the overarching mission to improve the quality and quantity of science focused on three types of “special populations” as defined by NCATS [As one step toward addressing the unmet need for more diverse research populations ,6,7, in by NCATS : childrePrevious reports have described studios and/or consultation services as successful mechanisms to support community-based research –11. “GraIn this paper, we describe the implementation of the Special Populations Consultation Service and short-term outcome metrics. Our aims were to (1) assess the feasibility and acceptability of this consultation model and (2) estimate the impact based on self-reported metrics and grant funding outcomes.The Special Populations Consultation Service was designed for academic researchers conducting special populations (SP) research. Following NCATS, we defined SP research as research involving children, older adults, and/or populations affected by health disparities .The Special Populations Consultation Service is available at no cost to all postdoctoral researchers and faculty members affiliated with any of the four institutions that comprise the UCLA CTSI: UCLA and its three partner institutions, Cedars-Sinai Medical Center, Lundquist Institute for Biomedical Innovation at Harbor-UCLA Medical Center, and Charles R. Drew University of Medicine and Science. We promoted the consultation service via CTSI flyers/online materials describing the service, word of mouth, and local presentations by ISP program staff and faculty.The UCLA CTSI ISP core leadership team consists of two faculty co-directors funded at 20% effort, a full-time program manager and a part-time (50%) community outreach director. An executive committee including representatives from each of the three partner CTSI institutions meets regularly with the leadership team to provide substantive input on all ISP program activities, including the Special Populations Consultation Service. As the point person for consultation requests, the ISP program manager solicits appropriate expert consultants and reviewers, schedules consultations, and collects and distributes materials to/from consultants and clients. Potential consultants are selected from the pool of NIH-funded scientists across all UCLA CTSI institutions, based on appropriate content expertise as well as reputation for being skilled grant reviewers and/or project or career consultants. We additionally prioritized selecting consultants with research expertise  in the NCATS CTSI-defined “special population” that was the focus of the consultation .Faculty reviewers participated in the consultations without compensation.1) and CV to the ISP program manager; the form is tailored to the specific type of consultation.The Special Populations Consultation Service provides three consultation types: (1) internal, presubmission grant reviews , (2) career consultations, and (3) project-specific consultations. Consultations are generally conducted in-person with all expert consultants/reviewers together at one time along with the consultation service recipient; occasionally, reviewers call in by phone. Clients are encouraged to audiotape the consultation with consent from all consultants. Interested faculty/trainees doing SP research seeking a consultation submit an electronic “Consultation Service Intake Form” . When a career development grant is being reviewed, the primary mentor sometimes attends as well. The studios are held 4–6 weeks prior to the targeted submission deadline. Potential grant mechanisms include NIH funding mechanisms  or any type of R-level application) and Patient-Centered Outcomes Research Institute (PCORI) proposals. The intake request form solicits details about the grant application . The investigator is also asked to suggest potential reviewers and provide a date when a draft of the grant will be available. However, the ISP program reviews the work of prospective grant reviewers very carefully to select experienced, grant-funded faculty reviewers.The ISP program manager then invites faculty members via electronic mail to serve as grant studio reviewers. The invitation includes a summary of the grant proposal details, as well as the applicant’s specific aims page (when available). After the grant studio has been scheduled, the applicant submits a grant draft proposal to the program manager via email 7 days prior to the scheduled grant studio. The program manager sends this to the reviewers and moderator along with an NIH-style review template and instructions. Reviewers complete and return their written reviews to the program manager and the moderator at least 1 day before the grant studio, allowing the moderator time to read the reviews; reviewers are also encouraged to send critiques directly to the applicant before the grant studio meets. Reviewers utilize an NIH-style nine-point rating scale  to provide an overall impact score as well as individual criterion scores ,21. ReviThe grant studio lasts 60 minutes. The first half simulates a regular NIH study section except that the grant applicant is in the room as a silent observer. The moderator starts by asking each reviewer for his/her overall impact score, then the primary reviewer provides a brief overview of the proposal and a 5–10 minute detailed summary of his/her review. Then the next reviewer gives his/her review, focusing on areas where he/she disagrees with the first reviewer and/or identifies new issues. Reviewers respond to each other’s comments, and the moderator summarizes key points and differences of opinion.During the second half of the hour, the client him/herself responds to the reviews, and the moderator and the reviewers work together to provide specific constructive feedback to help the grant applicant improve the application. In the final 5 minutes, the moderator and reviewers give their overall recommendations as to whether to submit as planned, or delay in order to allow time for recommended revisions; if substantial revisions are recommended, this recommendation will naturally depend upon how much time the client has to devote to revision before the submission deadline.After the grant studio, the moderator typically spends another 20–30 minutes individually with the client to help collate and prioritize the critiques and modifications. In addition, reviewers frequently offer to be available to assist in the future with either a specific issue on the same proposal or a different proposal. If they have not done so before the grant studio, reviewers send their reviews directly to the applicant after the studio.1) and CV. In this case, the client is asked to briefly describe his/her career goals in the next 5 years and indicate the specific question(s) for which he/she seeks consultation. The client also indicates how many hours per week he/she can commit to research in the next year and delineates a projected plan regarding grant proposal and manuscript submissions, and/or research presentations at conferences (if applicable).Suggested topics for a career consultation include (a) potential sources of funding, (b) collaboration opportunities, (c) the overall direction of the research, (d) promotion and advancement, (e) career transitions, and (f) strategies for achieving academic success. Career consultations are especially encouraged for faculty at career crossroads or transitions, e.g., near the end of a funding cycle, or deciding between different employment opportunities. Just as with grant studio clients, interested faculty/trainees seeking a career consultation submit an electronic “Consultation Service Intake Form”  conceptualizing a project, (b) identifying key collaborators, (c) identifying potential grant sources, (d) study design, (e) manuscript development, or (f) obtaining advice on operation-related issues such as IRB submissions, hiring staff, and subject recruitment and enrollment of special populations. The process for arranging and executing project-specific consultations is similar to that of career consultations, except with a focus on a specific project.2) is tailored using automatic branch patterns to the type of consultation and additionally includes general items measuring level of satisfaction with the quality of the consultation service, and whether or not the client would recommend the consultation service to their colleagues or department. The survey also probes the client’s opinion regarding the best feature of the consultation service, the extent to which the consultation service resulted in new opportunities, and how the client would improve the consultation service.After the consultation, the ISP program manager sends each consultation service recipient a link to an electronic post-consultation meeting survey via REDCap . The surFor grant studio consultations, the client indicates the extent to which the grant review session helped him/her prepare a stronger grant proposal, how much it changed and/or helped their NIH application, and whether he/she changed the timing of their grant submission based upon the grant studio. For career consultations, the client indicates the degree to which the career consultation changed and/or helped their career planning, whether or not they feel more confident about meeting their career goals, and whether or not they have a concrete plan following the consultation. For project-specific consultations, the client indicates the degree to which the consultation changed and/or helped his/her project and to specify whether and/or how he/she changed the project as a result of the consultation.n = 42, 71%), followed by project specific  and career consultations . Overall, 64% of the consultations involved research focused on children; 16% involved research focused on older adults. Altogether, 51% focused on racial/ethnic minorities or other disparity population . Clients were most frequently female (69.5%); 12% self-identified as Latino and 12% as Black or African-American. Most were at the rank of Assistant Professor (64%), had NIH early stage investigator status (71%), and had an MD degree (51%). The Special Populations Consultation Service was utilized by investigators from all partner institutions.Between September 2016 and December 2019, the Special Populations Consultation Service provided 59 consultations (Table n = 43) completed and returned it. Figures We began using the standardized Consultation Service Intake Request Form and the Post-Consultation Survey in January 2017. Of 49 clients sent the post-consultation survey, 88% . The unit of analysis for funding outcomes is, therefore, 38 representing the number of unique grant applications. Grant submissions were stratified by award status . The success rate ,14 was dn = 2, 50%) or “slightly”  with their career planning; all 4 reported feeling more confident about meeting their career goals and endorsed having a concrete career plan following the consultation.All clients who participated in a career consultation completed the evaluation and reported that the consultation helped either “moderately” (n = 11), 91% reported that the consultation changed/helped their project either “a great deal”  or “moderately” .Of the clients who completed the evaluation (n = 47) had clinical/research expertise in the CTSI special population focus. Approximately two-thirds of invited reviewers accepted the invitation; the most common reason cited for declining the invitation was unavailability due to travel or personal grant proposal deadlines. For the grant studios, most consultants reported spending approximately 2–3 hours on their grant review. Though we did not formally measure faculty experience, most reported informally that they found participating in the Special Populations Consultation Service to be a positive experience, as evidenced by the fact that 90% (n = 19) of reviewers and senior consultants who were invited a second time agreed to participate.To date, 58 of the 59 of the consultations included the participation of at least one senior faculty consultant with expertise in the CTSI “special population”  that was the focus of the consultation. Overall, 67 different consultants from five institutions and 18 departments, including leaders from 8 programsWe successfully implemented a new Special Populations Consultation Service designed for academic investigators at the UCLA CTSI hub. This consultation model has demonstrated feasibility and shows preliminary evidence of impact based upon client surveys indicating high satisfaction and reported change in career plans. Though the observational nature of this study precludes attributing causality, it is encouraging that the Special Populations Consultation Service was associated with relatively high rates of successful grant funding, particularly for career development grants.Among the three types of consultations offered, the grant studios were the most frequently utilized. While the Special Populations Consultation Service was used predominately by women, junior faculty, investigators with MD degrees, and those conducting pediatrics research, the consultation service reached a wide range of clients, including mid-career and senior investigators, those with PhD or MD/PhD degrees, and those conducting disparities research. In addition, although the Special Populations Consultation Service targeted research focused on SP research and not under-represented minority (URM) researchers, it is interesting that 14 (24%) recipients were URM, a much higher proportion than exists among all researchers at UCLA. Overall, the Special Populations Consultation Service appeared to meet a need at our CTSI hub – namely, assistance with peer review of extramural funding applications for faculty applicants across multiple departments, regardless of academic rank.Compared to formal grant studios described in the literature which were designed to reach prospective clients in the School of Nursing  or DeparPreliminary outcomes for CDA, in particular, appeared to benefit from the grant proposal studios. Compared to the NIH CDA success rate of 32.5% in fiscal year 2018, we observed a high success rate, with half of CDA applications reviewed through the Special Populations Consultation Service being funded; this success rate is comparable to CDA funding outcomes reported for other grant studio recipients . The R sOur number of project-specific and career-specific consultations were small, and arguably underutilized. Nevertheless, frequently, clients reported that the consultation “resulted in a major change,” suggesting that measurable outcomes such as reduced burnout, successful grant funding, and promotions might be important downstream outcomes. For example, through the Special Populations Consultation Service, a junior faculty member in the Department of Pediatrics with a research background in statistical modeling was introduced to an implementation science framework that she was previously unaware of and introduced to an expert in homelessness research; she subsequently rewrote a CDA application and a new R21 application using this new framework and is developing a third grant application with the new collaborator.There are a number of limitations to this small observational study. First, we did not formally assess the impact on the client for enhanced inclusion of special populations (SP) in the post-consultation survey. Second, as institutional comparators  are not available, it is not possible to attribute precisely the degree to which grant studios helped grant applications or contributed to funding. Likewise, it is not possible to directly quantitate the degree to which the Special Populations Consultation Service resulted in more faculty or trainees conducting research or pursuing careers in SP. In the early days of this model, we have disproportionately drawn consultations from UCLA-based researchers and clients conducting pediatric research. This may be in part because grant review services are already accessible to geriatric researchers through the NIA-funded UCLA Resource Center for Minority Aging Research (RCMAR) in the Department of Medicine and the UCLA Pediatrics Department policy of requiring internal peer review for faculty who submit a NIH CDA or their first R01 grant.We are broadening our outreach to increase utilization of the Special Populations Consultation Service from investigators from other departments and the other three UCLA CTSI-affiliated institutions. Although the consultation service is moderately busy, there is capacity for growth across our four institutions. To date we have not had difficulty recruiting faculty reviewers and/or consultants, but as we expand, we are considering implementing an incentive system  with pubImplementing a Special Populations Consultation Service across multiple departments and institutions was feasible. Though future research is needed to examine long-term outcomes and expanded metrics, the Special Populations Consultation Service has become an important mechanism for increasing research focused on SP within the UCLA CTSI.


We have previously reported reduction of cardiac herniation following intrapericardial pneumonectomy with pleural perfusion of saline in 2018.The authors confirm that there is no conflict of interest.


Objectives: To estimate the jitter parameters (single-fiber electromyography) in myasthenia gravis patients mostly by electrical activation in Frontalis, Orbicularis Oculi, and Extensor Digitorum muscles using a concentric needle electrode.Methods: Between 2009 and 2019, a total of 97 myasthenia gravis patients, 52 male, and mean age 54 years were included.Results: Any abnormal jitter parameter in individual muscles was 90.5% , 88.5% (Orbicularis Oculi), and 86.6% (Extensor Digitorum). Any jitter parameter combining Orbicularis Oculi and Frontalis muscle was abnormal in 100% for the ocular, and in 92.9% for the generalized myasthenia gravis. The most abnormal muscle was Orbicularis Oculi for the generalized, and Frontalis for the ocular myasthenia gravis. The decrement was abnormal in 78.4%, 85.9% for the generalized, and 25% for the ocular myasthenia gravis. The mean jitter ranged from 14.2 to 86 μs (mean 33.3 μs) for the ocular myasthenia gravis and from 14.4 to 220.4 μs (mean 66.3 μs) for the generalized myasthenia gravis. The antibody titers tested positive in 86.6%, 91.8% for the generalized, and 50% for the ocular myasthenia gravis. Thymectomy was done in 48.5%, thymoma was found in 19.6%, and myasthenic crisis occurred by 21.6%.Conclusion: The jitter parameters achieved a 100% abnormality in ocular myasthenia gravis if both the Orbicularis Oculi and Frontalis muscles were tested. There was a high jitter abnormality in generalized myasthenia gravis cases with one muscle tested, with about a 2% increase in sensitivity when a second is added. Concentric needle electrode jitter had high sensitivity similar to the single fiber electrode (93.8%), followed by antibody titers (86.6%), and abnormal decrement (78.4%). The neuromuscular transmission is compromised in several diseases, like myasthenia gravis (MG). It can be evaluated by the single-fiber electromyography (SFEMG), a technique developed in the early 1960s by Erik Stålberg and Jan Ekstedt in Sweden . The tesMyasthenia gravis is an autoimmune disorder affecting NMJ, usually associated with antibodies to the acetylcholine receptor (AChR) in about 85%. In 10–20% of patients with generalized MG (GMG) and about 50% of patients with ocular MG (OMG), there are no detectable antibodies to the AChRs (Orbicularis Oculi (OO). It should be stressed that increased jitter is not equal to myasthenic disorder but is also seen in other conditions, particularly reinnervation (The sensitivity of SFEMG is about 88% in OMG and 95–100% in GMG . Similarervation . IncreasExtensor Digitorum (ED) and OO muscles in 24 MG patients using both single fiber electrode (SFE) and CNE. Papathanasiou and Zamba-Papanicolaou  muscles.Disposable concentric needle electrodes (CNE) is currently used for jitter measurement , 11, duenicolaou  found nonicolaou . In our nicolaou , is prefnicolaou , 27, we the worst through disease,” and “the best after treatment” at the last visit. Worst MGFA was considered for the OMG or GMC distinction. Concentric needle electrode jitter recordings and antibody measurements, either to AbAChR or MuSK, were studied the same day while RNS may have been performed at another time up to 21 years separation in time.Between August 2009 and September 2018, we retrospectively studied hundred-five patients, highly suspected of having MG. They were referred for CNE jitter measurements. Patients to be eligible for being included had to present at least one of the following; fluctuating weakness, unequivocal clinical response to pyridostigmine or other anticholinesterase drugs, and at least one of the following; positive acetylcholine receptor antibody (AbAChR) titer (>0.40 nmol/L), positive muscle-specific tyrosine kinase antibody (AbMuSK) titer (≥0.02 nmol/L), or decrement of at least 10% on slow (2–3 Hz) repetitive nerve stimulation (RNS) studies. The first of their jitter studies being reported. The severity of disease was determined clinically according to the Myasthenia Gravis Foundation of America (MGFA) clinical classification from I, ocular weakness, to II-V, generalized weakness , and defNatus™ UltraPro (USA) machine. A few cases came from other services, and the RNS was done in different machine trades. Repetitive nerve stimulation was done in all patients, and the most pronounced and reliable quality recording decrement was considered anytime since the MG beginning. Several nerve-muscle settings, either distal, proximal, or facial, were done. Routine rules for RNS were followed. The distal limb temperature was kept warm (>32°C). The patients on cholinesterase inhibitors (mostly pyridostigmine) were asked to withhold the medication 24 h before the test if medically not contraindicated. The limb tested was adequately immobilized. Adhesive superficial electrodes were used. A supramaximal stimulation was delivered, about 10–20% above the intensity level needed for a maximal response. There was no rigorous protocol, but most of the cases had been tested for at least two muscles, distal limbs, and either proximal or facial unless the first test showed an unequivocal abnormal decrement. The most commonly nerve-muscles studied were the median nerve to the Abductor Pollicis Brevis (APB) muscle  with 7 or 10 stimuli. A decremental response higher than 10% of the forth to the first amplitude or area  response was considered abnormal. In all cases, the compound muscle action potentials had an amplitude within normal limits. In 25 cases, the RNS studies were done at rest and repeated 2, 3, and 4 min after 60 s of strong voluntary activation. Maximal decrement was considered.Most recordings were done in the Portable Keypoint or KeypointNet electromyograph  and some in the ) muscle , the uln2 and, Natus™ Dantec® DCN Disposable Concentric Needle Electrode, 25 × 0.30 mm (30G), recording area 0.02 mm2. Both electrodes are routinely used and approved by the Brazilian Agency for Health Surveillance (ANVISA).All jitter measurements were performed on the Natus™ Keypoint-Net  or Natus™ UltraPro (USA) machines with in-built software developed explicitly for the SFEMG test. The measurement of jitter parameters was done using disposable concentric needle electrodes (CNE) of two brands: Ambu® Neuroline Concentric, 25 × 0.30 mm (30G), recording area 0.02 mm2 . The first author (JAK) performed all jitter measurements, and the last author (ES) revised, when necessary, the digital recordings. Cholinesterase inhibitors may mask abnormal jitter when the abnormality of neuromuscular transmission is mild  for each pair of potentials (voluntarily activation), or each spike , using ideally 100 pair/spikes (we accepted 50 in some circumstances).amplitude level,” i.e., by the temporal variation of the ascending lines of depolarization of the ASFAPs, or by “the peak,” i.e., by the temporal variation of the mathematically defined peaks of the ASFAPs. Acceptance of potentials was based on the criteria established in the literature summarized in Sanders et al.  or the zygomatic branch (OO muscle) of the facial nerve percutaneously. We find the appropriate location for the bar fixation by adjusting the stimulus intensity to produce a slightly visible muscle twitch. In general, this could be achieved at about 5–7 mA. Stimulation parameters were 10 Hz frequency  using rectangular pulses of 0.10 ms duration. The recording position and stimulus intensity were adjusted to give a minimum number of spikes in the response. The most important here is to assure that each spike accepted for analysis had a supraliminal stimulation. If a spike showed increased jitter, the intensity was raised slightly to check for correct stimulus intensity. When the stimulus intensity was raised from subliminal to adequate, the spike latency decreased somewhat, the jitter decreased, the impulse blocking disappeared. Frequently some more spikes came out, but these must be skipped or undergo the test for adequate stimulation.axon-reflex,” and F-waves , AMBU A/S ], 25 mm, was introduced into the muscle near the motor point (active); another similar electrode (reference) was introduced 2–3 cm in any direction, to the insertion site of the active electrode, following standards already described , 14, 29. F-waves , 31. TheThe CNE was introduced into the chosen muscle, and after minimal maintained voluntary contraction, the ASFAPs were recorded. After slight electrode movements, a pair of ASFAPs was recorded, with both potentials belonging to the same motor unit. The trigger was usually set to the highest amplitude spike. We excluded the ASFAP pairs without clear separation between them (>300 μs), the records with <50 ASFAP pairs, the ASFAP pairs with interpotential interval (IPI) >4 ms to avoid the effect of velocity recovery function (VRF), or when the shape criteria were not fulfilled. The mean value of the sorted differences (MSD) was also calculated, which expresses the consecutive differences according to the potential pairs' frequency of discharge. When the inter-potential interval (IPI) variation is higher than 4 ms and not constant, there may be interference from the VRF; in a few situations when it occurs we use the MSD if the MCD/MSD ratio is higher than 1.25, or with recent software, the smaller of the two parameters is chosen automatically. The other electrophysiological parameters were the same as those already described in the previous technique.t-test made the comparison of parametric variables with a significance of 0.05. The comparison of non-parametric variables was made by the Mann-Whitney non-parametric test (U-test) to verify the medians' equality. Correlation of the mean jitter values (MCD) with variables was made with a linear model, calculating the R-square to show the correlation power of jitter in the regression line.Descriptive statistics calculated the mean jitter (MCD) values of the 97 MG patients and all other parameters: mean and standard deviation for normal or Gaussian distribution or median/percentage for non-normal distribution. Anderson-Darling normality test was used. The Student's From the 105 cases selected, we excluded 8, leaving 97 cases for analysis. The exclusion was based on the full constellation of normal jitter parameters, no abnormal decrement, no antibody increased titers either to AChR or MuSK, no or just a disputable fluctuating weakness, and no response to anticholinesterase inhibitor drugs or prednisone for at least a year. With all tests still negative for MG for 1 year, alternate diagnoses were considered.The majority of the cases (74/97 or 76.3%) considered themselves free of symptoms for daily activities. Overall, 94 (96.9%) were taking daily pyridostigmine, 53 (54.6%), regular or alternated prednisone, and 26 (26.8%), azathioprine. One case was in remission (medicine-free). The most frequent combination was pyridostigmine plus prednisone , and pyridostigmine, prednisone plus azathioprine . Just one patient used the combination pyridostigmine plus azathioprine. No circumstances went to death due to the MG itself. Three cases died from other reasons; aortic aneurysm, acute myocardial infarction, and heart failure, one case each. Thymectomy was performed on 47 (48.5%) patients with thymoma found in 40.4% . Myasthenic crisis occurred in 21 cases (21.6%) without fatalities .The worst MGFA was considered for the OMG or GMC distinction. Ocular MG was defined for 12 cases (12.4%), meaning that patients had maintained just ocular symptoms (eyelid drop and diplopia) for at least 2 years . Generalized MG was defined for 85 cases (87.6%), meaning that patients had extensive weakness outside the ocular muscle symptoms. Some of the variables are shown in The mean abnormal AbAChR titer was 14.14 ± 21.05 nmol/L . The AbAChR was abnormal in 84.5% and antiMuSKAb in 2.1%. The two MuSK positive patients were AbAChR negative . In eighAbnormal decrement was found in 76/97 patients 78.4%) at any time of the disease, meaning that the RNS and the jitter analysis plus antibodies could be more than 10 years apart. In total, 258 tests were done with a mean of 2.7 per patient .4% at an. There wAmplitude and area parameters showed a similar degree of change in stimulation. When only one of them was abnormal, the study was considered abnormal (this occurred in one case). In a comparison between facial and the distal group, eight cases were only abnormal in facial muscles, and in two instances, just the distal muscles were abnormal. All abnormal proximal muscles share the abnormality with the facial muscles. Despite the increase of the decrement after 2–4 min of 60 s of maximal effort in eight cases (25 nerve-muscles), in only 1, the values went from normal (<10%) to abnormal (more than 10%).A total of 170 muscles were tested. Overall, 91/97 MG patients (93.8%) had at least one muscle and one abnormal jitter parameter. Overall, 79/85 GMC patients (92.9%) had at least one muscle and one abnormal jitter parameter. Overall, 12/12 OMG patients (100%) had at least one muscle and one abnormal jitter parameter. Just one muscle was tested in 25 patients, two muscles in 71 patients, and three muscles in one patient. The jitter parameters in all tested muscles for the GMG and OMG are displayed in For the OMG, neither OO  nor FR  individually could provide a 100% abnormality. The combination of the mean jitter measurement for the OO and the FR muscles added 5/12 abnormal cases and reached 100% abnormality. For the GMC group (85 cases), the combination of two tested muscles helped for detecting neuromuscular transmission dysfunction in just two additional cases, and the percentage of cases with abnormal jitter for any jitter parameter went from 90.6 to our final number of 92.9%. The overall sensitivity for all cases and GMC and OMG forms are shown in In patients with GMG and OMG, we found spikes with an impulse blocking in 20.9 and 5.8%, respectively, either ED, FR, or OO muscles. Overall, impulse blocking was found in 19.3%. Impulse blocking in MG cases after therapy (similar to this study) was found in 5.2% (ED muscle) and 20.6% (FR muscle) for ocular and 9.9–38.3% (ED muscle) and 20.6–47.6% (FR muscle) for generalized forms , 27 withDespite the small cohort, a comparison between OMG  and GMG  was done for some parameters and is shown in We retrospectively reviewed a larger MG cohort than our previous report , 27 measThis observational, consecutive, and retrospective survey was designed to study the general feasibility of CNE jitter analysis in MG. The results do not represent the techniques' sensitivity and specificity. All three of the most studied muscles were used for the activation, ED, OO, and FR. Abnormal jitter was found in 93.8% for any, regardless of MG type. This percentage was more than 90%, and 90.5% found in our previous reports , 27 may Our results showed the requirement to test two muscles  for the OMG in most since the isolated muscle jitter results may not fully reflect the abnormality, whereas the combination FR and OO gave 100%.For the GMG, any abnormal jitter parameter was found in 92.9%. Our results showed the requirement of two muscle tests for the GMG would be unnecessary in most since the isolated muscle jitter results are abnormal in a high percentage. If the first muscle is normal, a second muscle should be tested, increasing the sensitivity by just 2%. This may indicate a more even distribution of abnormalities among muscle in GMA than in OMG.The analysis of the six patients without abnormality of any jitter parameters showed 4 cases with previous abnormal decrement obtained 9–21 years earlier, and three cases with abnormal AbAChR titers, confirming a neuromuscular transmission dysfunction in all cases at some time. This unexpected finding of the discrepancy between jitter and RNS may be explained by the delay between the tests. In the two examples with striking previous abnormal decrement and negative abnormal AbAChR titers, a congenital myasthenic syndrome should be suspected. In our previous studies , 27 simiNasalis), the Trapezius, and the Anconeus could increase in 33% the test sensitivity  in 75% of patients with GMG, the same as here. In OMG and OMG, RNS was reported abnormal in 10–48 and 48.5%, respectively . Our primary purpose here was related to the CNE jitter analysis). The first limitation is that the study was observational and retrospective. We have different protocols for some electrophysiological data as RNS and sequence of examining muscles for the jitter measurements. Besides, the activation technique was not the same for all patients. The second limitation is that we could not routinely test for the congenital myasthenic syndrome or congenital myopathies when there was no response to MG therapy. It occurred in three cases with negative antibodies titers. A third limitation is the RNS and jitter studies may have been performed many years apart, and we may have a completely different clinical situation on two occasions. However, these limitations do not influence the main results and conclusions.In conclusion, the present study confirms that CNE can be reliably used for the jitter analysis and impulse blocking for a neuromuscular transmission dysfunction suspicion as MG. For the GMG, we found a high rate of abnormality for any jitter parameters, regardless of one or more muscles were studied. For the OMG, we found a very high percentage of abnormality for any jitter parameters (100%) only using combined muscles, OO, and FR in the same exam. Therefore, in OMG, a second facial muscle should be studied if the first showed normal results. These findings were similar to what has been reported in a more extensive series with SFE. Technically, CNE jitter measurement was much more easily obtained, less painful, and less time consuming for the facial muscles than for the ED. We found the combined distal and ocular RNS studies was the most useful for having a decremental response.The raw data supporting the conclusions of this article will be made available by the authors, without undue reservation.The studies involving human participants were reviewed and approved by Ethics committee of the Faculdade Estadual de Medicina de São José do Rio Preto (FAMERP), Av. Faria Lima 5416, 15090-000, São Paulo, Brazil, where the SFEMG test was performed. The patients/participants provided their written informed consent to participate in this study.JK and ES contributed to the conceptual project design, statistical analysis, data interpretation, and manuscript draft. JK did all SFEMG tests. GP contributed to the data collection and management. All authors contributed to the manuscript's critical review and approval.The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.


Clinical chemistry analysis of body fluids from non-blood or urine sources presents a technical challenge for clinical laboratories. Examples of body fluids include biliary secretions, cerebrospinal fluid, cyst contents, dialysate, gastric aspirates, peritoneal fluid, pleural fluid, stool, surgical drain fluid, synovial fluid, and wound exudates. The heterogeneous nature of these body fluids presents technical difficulties for analysis. For example, body fluid specimens may have presence of hemolysis, icterus, or lipemia (‘interference indices’) that can interfere with clinical chemistry analysis. In the related research article, we analyzed the distribution of these interference indices and body fluid samples submitted for analysis at an academic medical center central clinical laboratory and compared this to data from serum/plasma specimens. The data in this article provide the body fluid type, clinical chemistry testing ordered, interference indices, and whether the indices exceeded the manufacturer's recommendations in the package insert for serum/blood specimens. The analyzed data are provided in the supplementary tables included in this article. The dataset reported is related to the research article entitled “Review of interference indices in body fluids specimens admitted for clinical chemistry analyses” [1]. Specific data fields include: location/unit at time of testing , age in years, legal gender, exact body fluid type, category of body fluid, hemolysis index, icteric index, lipemia index, and quantitative analyte concentrations for 12 different clinical chemistry assays . The data include the quantitative analyte concentration for the clinical chemistry test  and whether the interference index exceeded the parameter for that analyte for serum/plasma as reported in the manufacturer package insert.Supplementary file 1: Data for 2752 unique body fluid specimens divided into categories•Supplementary file 2: Data for 25,507 unique serum/plasma specimens for 12 different clinical chemistry assays . Specific data include hemolysis index, icteric index, lipemia index, and quantitative analyte concentrations for the different clinical chemistry assays. The data include the quantitative analyte concentration for the clinical chemistry test  and whether the interference index exceeded the parameter for that assay for serum/plasma as reported in the manufacturer package insert.We analyzed interference indices in body fluid and serum/plasma samples submitted for analysis at an academic medical center central clinical laboratory 2All analyses were performed on Roche Diagnostics cobas 8000 analyzers (c502 and c702) as reported elsewhere


The authorities in the domain of shock physiology, Vincent and colleagues, have recently offered a concise perspective on intravenous fluid administration . They distroke volume is the closest clinically-available approximation of the cardiac length-tension relationship. This point is highlighted by a hypothetical example.Historically, fluid responsiveness (FR) has been defined by change in cardiac output (CO = heart rate x stroke volume) as CO is a key determinant of oxygen delivery , 2. IgnoA patient in early septic shock has a heart rate (HR) of 120 beats per minute (BPM), stroke volume (SV) of 51 mL and, therefore, a CO of 6.1 L per minute (L/min). The patient is given 30 mL/kg of balanced crystalloid; subsequently HR falls to 90 BPM and SV rises to 65 mL resulting in a CO of 5.9 L/min. Was this patient harmed by intravenous fluids? Is this patient ‘fluid unresponsive’ despite SV rising by over 25%?fall in cardiac output, the patient above may have significantly increased ventricular oxygen delivery with intravenous fluids, especially if there is co-morbid coronary artery disease and/or ventricular hypertrophy. These principles could partly explain recent data associating diminished diastolic shock index  with improved outcome [low HR and high diastolic pressure is a good prognosticator in septic shock.An implicit, mathematical assumption of CO is that its augmentation is beneficial independent of the relationship between SV and HR; this may not be universally true. For example, the coronary circulation is perfused preferentially during diastole. Therefore, diminishing HR augments diastolic time and subendocardial perfusion . Accordi outcome . In otheThus, because CO comprises two variables that may diverge as a normal, adaptive response or following beneficial therapy, relying on it as a lumped index of ‘fluid responsiveness’ may mislead. Accordingly, clinicians and researchers should rely not merely on CO as it may conceal the effect of fluids on the cardiac length-tension, i.e., Frank-Starling, relationship. 2), this will not be achieved by increasing SV without an increase in CO. A decrease in hemoglobin concentration due to a dilutional effect of a large bolus of fluid may also limit the increase in DO2.We would like to thank Drs Kenny and Barjaktarevic for their comment about our paper on fluid challenge . The autMeasurements of CO rather than SV also have some practical advantages. First, the decrease in heart rate can vary during a fluid challenge. In a study evaluating fluid responsiveness in 491 critically ill patients , heart r2 is what matters for the tissues.Perhaps, the most important message is that the management of critically ill patients is complex and cannot be based on one variable only. Using SV to assess fluid response is not wrong if one looks at the Frank–Starling relationship, but ultimately the DO