The action potential (AP) waveform controls the opening of voltage-gated calcium channels and contributes to the driving force for calcium ion flux that triggers neurotransmission at presynaptic nerve terminals. Although the frog neuromuscular junction (NMJ) has long been a model synapse for the study of neurotransmission, its presynaptic AP waveform has never been directly studied, and thus the AP waveform shape and propagation through this long presynaptic nerve terminal are unknown. Using a fast voltage-sensitive dye, we have imaged the AP waveform from the presynaptic terminal of male and female frog NMJs and shown that the AP is very brief in duration and actively propagated along the entire length of the terminal. Furthermore, based on measured AP waveforms at different regions along the length of the nerve terminal, we show that the terminal is divided into three distinct electrical regions: A beginning region immediately after the last node of Ranvier where the AP is broadest, a middle region with a relatively consistent AP duration, and an end region near the tip of nerve terminal branches where the AP is briefer. We hypothesize that these measured changes in the AP waveform along the length of the motor nerve terminal may explain the proximal-distal gradient in transmitter release previously reported at the frog NMJ.

SIGNIFICANCE STATEMENT The AP waveform plays an essential role in determining the behavior of neurotransmission at the presynaptic terminal. Although the frog NMJ is a model synapse for the study of synaptic transmission, there are many unknowns centered around the shape and propagation of its presynaptic AP waveform. Here, we demonstrate that the presynaptic terminal of the frog NMJ has a very brief AP waveform and that the motor nerve terminal contains three distinct electrical regions. We propose that the changes in the AP waveform as it propagates along the terminal can explain the proximal-distal gradient in transmitter release seen in electrophysiological studies.

Autism spectrum disorder (ASD) is characterized partly by atypical attentional engagement, reflected in exaggerated and variable responses to sensory stimuli. Attentional engagement is known to be regulated by the locus ceruleus (LC). Moderate baseline LC activity globally dampens neural responsivity and is associated with adaptive deployment and narrowing of attention to task-relevant stimuli. In contrast, increased baseline LC activity enhances neural responsivity across cortex and widening of attention to environmental stimuli regardless of their task relevance. Given attentional atypicalities in ASD, this study is the first to evaluate whether, under different attentional task demands, individuals with ASD exhibit a different profile of LC activity compared with typically developing controls. Males and females with ASD and age- and gender-matched controls participated in a one-back letter detection test while task-evoked pupillary responses, an established correlate for LC activity, were recorded. Participants completed this task in two conditions, either in the absence or presence of distractor auditory tones. Compared with controls, individuals with ASD evinced atypical pupillary responses in the presence versus absence of distractors. Notably, this atypical pupillary profile was evident despite the fact that both groups exhibited equivalent task performance. Moreover, between-group differences in pupillary responses were observed specifically in response to task-relevant events, providing confirmation that the group differences most likely were specifically associated with distinctions in LC activity. These findings suggest that individuals with ASD show atypical modulation of LC activity with changes in attentional demands, offering a possible mechanistic and neurobiological account for attentional atypicalities in ASD.

SIGNIFICANCE STATEMENT Individuals with autism spectrum disorder (ASD) exhibit atypical attentional behaviors, including altered sensory responses and atypical fixedness, but the neural mechanism underlying these behaviors remains elusive. One candidate mechanism is atypical locus ceruleus (LC) activity, as the LC plays a critical role in attentional modulation. Specifically, LC activity is involved in regulating the trade-off between environmental exploration and focused attention. This study shows that, under tightly controlled conditions, task-evoked pupil responses, an LC activity proxy, are lower in individuals with ASD than in controls, but only in the presence of task-irrelevant stimuli. This suggests that individuals with ASD evince atypical modulation of LC activity in accordance with changes in attentional demands, offering a mechanistic account for attentional atypicalities in ASD.

‘What on earth were they doing there?’ one researcher asks

With no new infections reported in Hubei province in recent days, restrictions are easing up—but experts worry about possible 'second wave' of cases

Mary Pearson, who was briefly engaged to the writer's brother, may be the real-life counterpart of Lydia Bennet from "Pride and Prejudice"

Scientists discover neurotoxin-producing bacteria living on the skin of rough-skinned newts

Darin Isaac was elected on Wednesday as the new chief of the Selkirk First Nation in Yukon. Isaac also held the position for two terms from 2005 to 2011. He has also served as a councillor for three terms.

Two men are charged in connection with an illegal drug distribution operation after Winnipeg police seized more than $2.2 million worth of methamphetamine, cocaine and ecstasy.

Philip Pynn is being released from federal prison for a second time, after breaching conditions landed him back behind bars last year — but it's not clear where he can live.

Successful modification of the bacterial artificial chromosome (BAC) after two-step BAC engineering is confirmed in two separate polymerase chain reactions (PCRs). The first reaction (5' co-integrate PCR) uses a forward 5' co-integrate primer (a sequence located upstream of the 5' end of the A-box) and a reverse 3' primer on the vector (175PA+50AT) or within the reporter sequence or mutated region as appropriate. The second reaction (3' co-integrate PCR) uses a forward 5' primer on the recA gene (RecA1300S) and a reverse 3' co-integrate primer (a sequence located downstream from the 3' end of the B-box). Those colonies shown to be positive in PCR analysis are further tested for sensitivity to UV light. After the resolution, colonies that have lost the excised recombination vector including sacB and recA genes become UV light sensitive.

Bacterial artificial chromosome (BAC) clones are rendered electrocompetent and transformed with the recombinant shuttle vector, pLD53SCAB/AB-box. Cointegrates are selected by growth on chloramphenicol and ampicillin to ensure recombination of the shuttle vector into the BAC.

Plasmid DNA is prepared from the recombinant shuttle vector pLD53.SCAB/A-B created by cloning of the A and B homology arms for two-step bacterial artificial chromosome (BAC) engineering. To confirm that the A-box and B-box arms have been successfully incorporated into pLD53.SCAB, the pattern of enzyme digestion of the modified plasmid is compared with that of the unmodified pLD53.SCAB. Once the shuttle vector is shown to carry the proper sequences, it is ready for transfer into the BAC host.

This protocol describes the preparation of the shuttle vector before its introduction into bacterial artificial chromosome (BAC) host cells for BAC two-step engineering. The homology arm sequences, prepared previously, are introduced by ligation into the digested shuttle vector DNA to provide sites for recombination within the BAC clone. Crude lysates of individual bacterial transformants serve as templates in polymerase chain reaction (PCR) analysis to confirm the presence of the homology arms in the recombinant shuttle vector.

The 700-bp A homology arm (A-box) and the 700-bp B homology arm (B-box) are amplified by polymerase chain reaction (PCR) using purified bacterial artificial chromosome (BAC) DNA as template for two-step BAC engineering. The resulting A-box PCR product contains an AscI site at its 5' end (the 5' primer incorporates an AscI site, and the 3' primer does not incorporate any restriction sites). The B-box PCR product contains an XmaI site at its 3' end (the 5' primer does not incorporate any restriction sites, and the 3' primer incorporates an XmaI site). The amplification products are then digested with the appropriate restriction endonucleases to render them suitable for cloning into the shuttle vector.

In two-step bacterial artificial chromosome (BAC) engineering, a single plasmid is introduced into the BAC-carrying cell lines. The shuttle vector pLD53.SCAB (or pLD53.SCAEB) carries the recA gene and the R6K origin, which requires the protein to replicate. PIR2 cells, expressing , are typically used for the amplification of the vector and maintain about 15 copies/cell of the donor vector, which is relatively stable in this host.

FSI Briefs No 3, April 2020. In response to the 2007-09 Great Financial Crisis (GFC), accounting standard setters introduced a new methodology to value loans based on expected credit losses (ECL). The previous approach, based on incurred losses, was viewed as procyclical and inconsistent with prudential objectives. In the wake of the Covid-19 pandemic, several prudential authorities and the Basel Committee on Banking Supervision (BCBS), introduced a series of measures to clarify how banks should consider various public and private debt relief programmes in their ECL estimates and in their calculation of regulatory capital. These measures are intended to incentivise banks to continue supporting the real economy, while reducing pressure on banks' ECL provisions, earnings and regulatory capital. Supervisory initiatives that provide capital relief should be augmented by severe constraints on the payment of dividends, bonuses and share buybacks. These joint actions will simultaneously expand banks' lending capacity and enhance their ability to absorb losses. Prudential authorities face difficult trade-offs as they confront the most severe economic crisis in modern times. Encouraging the use of flexibility in applicable accounting standards, while preserving market trust and transparency in the reported financial statements of banks, will be key in fostering both economic and financial stability.

Eight COVID-19 cases are now connected to that workplace, including six employees.

The Flint Registry is holding in-person enrollment across the city of Flint all week. Officials are trying to track the health of residents made ill by the Flint Water Crisis.

Global real residential property prices rose 1.4% year/year in aggregate in Q3 2019, reflecting subdued developments both in advanced (+ 1.5%) and emerging market economies (+ 1.3%).

From stage to sofa: NAC brings local arts to homes in new livestream initiative  Connected to India

Darin Isaac has been elected chief of the Selkirk First Nation while Jeremy Harper, Morris Morrison, Carmen Lee Baker and Ashley Edzerza were voted in as councillors. Cody Sims has been elected youth councillor.

The Pittsburgh Steelers selected Canadian receiver Chase Claypool in the second round of the NFL draft Friday night. Claypool was the 17th player taken in the round, 49th overall.

If you think it's cold this morning, just wait — the forecast low for Friday night is –3 C.

Rosario, Argentina :: Church members from a vulnerable community learn about human trafficking and experience care and respect.

Laurie Garrett, the prophet of this pandemic, expects years of death and “collective rage.”

Five members of the Penn State football team were selected in this past weekend's NFL Draft, marking the third straight year that the Nittany Lions have had at least five draft picks.

The 2013 Hope of Israel team shows motivation and unity during a month of intense ministry.

God uses theatrical evangelism camps to impact children from vulnerable populations as well as the short-term volunteers who serve.

OM EAST rejoices at God’s provision sent by post.

As expected, the number of passengers at Berlin airports fell in January. Tegel and Schönefeld dealt with a total of 2,252,265 passengers, 6.9% fewer than in the same month last year.

The Celtic Connections roots and traditional music festival recorded 100,000 visits this January.

Hamish Wilson, radio producer and actor

Lord Armstrong of Ilminster

Why hasn't every PC user on the planet upgraded to Windows 10 by now? Because Microsoft, as usual, can't communicate to anyone why they should.

Most teachers say that school discipline is inconsistent or inadequate, a new study from the Fordham Institute finds.

Rosario, Argentina :: Church members from a vulnerable community learn about human trafficking and experience care and respect.

Educators, public health authorities, and law enforcement are confronting an increasing number of cases in which youth made sexual images of themselves and other minors and transmitted them via cell phones and the Internet.

This study provides the first detailed and comprehensive national estimate of the percentage of youth who create and distribute various kinds of sexual images. (Read the full article)

Gallbladder disease in children is an evolving entity and studies suggest an increasing frequency of symptomatic pediatric gallbladder disease and resultant cholecystectomies.

Hispanic ethnicity and obesity are epidemiologically significant risk factors for symptomatic gallbladder disease in the pediatric population. (Read the full article)

Eating disorders are characterized by preoccupation with weight and shape, which is manifested by a refusal to maintain a normal weight. An exact determination of expected body weight (EBW) is critical for diagnosis and clinical management of these disorders.

The McLaren and Moore methods present with several limitations when calculating EBW for adolescents with eating disorders. A commonly agreed upon method for EBW calculation such as the BMI percentile method is recommended for clinical and research purposes. (Read the full article)

Asthma is a common obstructive pulmonary disease experienced during pregnancy. Clinical guidelines recommend women with asthma maintain asthma medication use during pregnancy. Epidemiologic studies suggest an association between several types of defects and asthma or asthma medication use during pregnancy.

Data from a large, population-based, multicenter, case-control study was used. This provides the opportunity to study specific birth defects with minimal heterogeneity in case groups, as well as control for a variety of potential confounders. (Read the full article)

Approximately 1.1% to 5.9% of febrile infants aged <90 days have bacteremia, but the incidence of bacteremia in this age is unknown. Escherichia coli, group B Streptococcus, and Staphylococcus aureus are the leading causes of bacteremia.

Bacteremia occurs in 2.2% of infants who have a blood culture drawn. The incidence rate of true bacteremia was 0.57 in 1000 full-term births. The most common pathogens were Escherichia coli (56%), group B Streptococcus (21%), and Staphylococcus aureus (8%). (Read the full article)

There is a perception among clinicians that methicillin-resistant Staphylococcus aureus (MRSA) bacteremia and/or meningitis result in a greater burden of disease than invasive infections attributed to methicillin-susceptible Staphylococcus aureus (MSSA) among very low birth weight (VLBW) infants.

VLBW infants with MRSA and MSSA bacteremia and/or meningitis have equivalent morbidity and mortality. These findings suggest that allocation of resources for prevention and treatment of both MRSA and MSSA infections among VLBW infants should be comparable. (Read the full article)

Autism is widely considered a heterogeneous disorder in terms of etiology and phenotype. Although autism is usually a lifelong disorder, little is known about the rate or timing of how children develop regarding their communication and social functioning.

Utilizing annual evaluations for a large population of children with autism, we describe the 6 most common trajectories from diagnosis through age 14 years. Trajectories revealed considerable variation, and high socioeconomic status children were more likely to experience rapid improvement. (Read the full article)

Preterm, growth-restricted infants are at high risk of necrotizing enterocolitis (NEC). NEC occurs most frequently in infants who have received enteral feeds. It is common practice to delay introduction of enteral feeds in these infants.

Early introduction of enteral feeds results in earlier achievement of full enteral feeding. Early feeding is not associated with a higher risk of NEC. Delayed feeding is associated with a higher risk of cholestasis. (Read the full article)

Nonadherence to antiretroviral therapy among children and youth with HIV is a frequent problem that can result in treatment failure and disease progression for this population. Children and adolescents face different barriers to adherence than adults infected with HIV.

Few studies have examined specific barriers to adherence as reported by children with perinatally acquired HIV and their caregivers. This report examines the agreement between child and caregiver perceptions of adherence barriers and the factors associated with these barriers. (Read the full article)

More than one-tenth pediatric patients use complementary and alternative medicines (CAM) for their medial conditions in the United States. Traditional Chinese medicine (TCM) is the most commonly used CAM in East Asia but large-scale epidemiologic studies are lacking.

In comparing TCM and non-TCM users among children in Taiwan, children’s age and parental TCM use were strongly associated with TCM use. Additionally, dyspepsia and allergic rhinitis were positively related to increasing TCM use. (Read the full article)

Neonatal sepsis is an important cause of under-5 childhood mortality. Infants born to HIV-infected mothers are at increased risk of morbidity and mortality, even if not having acquired HIV. This association needs further study during the neonatal period.

Maternal HIV infection was associated with increased vaginal colonization by Escherichia ecoli but not group B Streptococcus. Neonates born to HIV-infected mothers were only at increased risk of sepsis if they had acquired HIV-infection, but not if HIV-uninfected. (Read the full article)

There is evidence from both developed and developing countries that antiretroviral treatment significantly reduces mortality in HIV-infected children. However, in sub-Saharan Africa, numerous health system, financial, and human resource obstacles make delivering quality pediatric HIV care a challenge.

We describe the experience of the Baylor International Pediatrics AIDS Initiative in Malawi, Lesotho, and Swaziland. Despite challenges delivering pediatric treatment in these countries, mortality and clinical outcomes approaching those from developed countries are feasible. (Read the full article)

Pediatric osteoarticular infections can be treated with successful microbiologic and clinical outcomes with a transition from parenteral to oral therapy. The best way to determine the timing of this transition is neither well studied nor standardized.

A total of 193 (99.5%) of 194 pediatric patients with acute bacterial osteoarticular infections were successfully transitioned to oral therapy, determined by using a combination of clinical findings and C-reactive protein levels, representing the largest single-center data set analyzed. (Read the full article)

Retinal hemorrhages occur in accidental and inflicted traumatic brain injury (ITBI) and some medical encephalopathies. Large numbers and peripherally located retinal hemorrhages are frequently cited as distinguishing features of ITBI in infants, but the predictive value has not been established.

This prospective retinal imaging study found that a diagnosis of ITBI in infants and children can be distinguished from other traumatic and nontraumatic causes by the presence of >25 dot-blot (intraretinal layer) hemorrhages (positive predictive value = 93%). (Read the full article)