An epilepsy-associated SV2A mutation disrupts synaptotagmin-1 expression and activity-dependent trafficking

The epilepsy-linked gene , has a number of potential roles in the synaptic vesicle (SV) life cycle. However, how loss of SV2A function translates into presynaptic dysfunction and ultimately seizure activity is still undetermined. In this study, we examined whether the first SV2A mutation identified in human disease (R383Q) could provide information regarding which SV2A-dependent events are critical in the translation to epilepsy. We utilized a molecular replacement strategy in which exogenous SV2A was expressed in mouse neuronal cultures of either sex, which had been depleted of endogenous SV2A to mimic the homozygous human condition. We found that the R383Q mutation resulted in a mislocalization of SV2A from SVs to the plasma membrane, but had no effect on its activity-dependent trafficking. This SV2A mutant displayed reduced mobility when stranded on the plasma membrane and reduced binding to its interaction partner synaptotagmin-1 (Syt1). Furthermore, the R383Q mutant failed to rescue reduced expression and dysfunctional activity-dependent trafficking of Syt1 in the absence of endogenous SV2A. This suggests that the inability to control Syt1 expression and trafficking at the presynapse may be key in the transition from loss of SV2A function to seizure activity. SV2A is a synaptic vesicle (SV) protein, the absence or dysfunction of which is linked to epilepsy. However, the series of molecular events that result in this neurological disorder is still undetermined. We demonstrate here that the first human mutation in SV2A identified in an individual with epilepsy displays reduced binding to synaptotagmin-1 (Syt1), an SV protein essential for synchronous neurotransmitter release. Furthermore, this mutant cannot correct alterations in both Syt1 expression and trafficking when expressed in the absence of endogenous SV2A (to mimic the homozygous human condition). This suggests that the inability to control Syt1 expression and trafficking may be key in the transition from loss of SV2A function to seizure activity

Arizona\u27s Vulnerable Populations

Arizona’s vulnerable populations are struggling on a daily basis but usually do so in silence, undetected by traditional radar and rankings, often unaware themselves of their high risk for being pushed or pulled into a full crisis. Ineligible for financial assistance under strict eligibility guidelines, they don’t qualify as poor because vulnerable populations are not yet in full crisis. To be clear, this report is not about the “poor,” at least not in the limited sense of the word. It is about our underemployed wage earners, our single-parent households, our deployed or returning military members, our under-educated and unskilled workforce, our debt-ridden neighbors, our uninsured friends, our family members with no savings for an emergency, much less retirement

Finishing the euchromatic sequence of the human genome

The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers ∼99% of the euchromatic genome and is accurate to an error rate of ∼1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead

The Lord Howe Island Rodent Eradication: Lessons Learnt from an Inhabited Island

The 2019 rodent eradication on 1,455-ha Lord Howe Island was the second and largest attempted on a permanently inhabited island. With 350 residents, it presented numerous novel challenges, resulting in an operation best summarised in four words: Compromise, Commensal, Complexity, and Cost. A ground-based operation was conducted across the built-up portion of the island, some 300 ha, with aerial bait applied on forested higher ground (1,200 ha); brodifacoum was used exclusively for this attempted eradication. Initial community resistance and the presence of mice meant that almost 19,000 external bait stations were established within the Settlement, on a 10-m grid. The intensive grid was expected to result in numerous bait stations within rodents’ home ranges. An additional 3,500 internal bait stations were put in all buildings and 9,500 hand-broadcast points overlapped the aerial and bait station boundaries. Over 60 field staff were employed locally, from Australia and overseas, to run the toxic baiting operation for 5.3 months. On-going resistance from a small community group resulted in two legal challenges early in the operational stage, including one in the Australian Supreme Court. Additional complications included initial active opposition to private land access; unaccepted personnel by the private land owners; resistance to livestock removal requiring novel bait station infrastructure; possible significant bait loss to invertebrates; and a small proportion of rats apparently avoiding bait stations. A fundamental aim of future operations on inhabited islands should be that they are community-led, which is likely to take several years to mature to the operational stage. Eradication practitioners should prepare for a significantly more complex operation with a concomitant increase in resourcing and planning

Faculty Recital, Darryl Harper, clarinet, Disc One

First Half of Performance Darryl Harper: Those Who Make Believ

‘Don’t play the butter notes’: jazz in medical education

Jazz has influenced world music and culture globally – attesting to its universal truths of surviving, enduring, and triumphing over tragedy. This begs the question, what can we glean in medical education from this philosophy of jazz mentoring? Despite our training to understand disease and illness in branching logic diagrams, the human experience of illness is still best understood when told as a story. Stories like music have tempos, pauses, and silences. Often they are not linear but wrap around the past, future, and back to the present, frustrating the novice and the experienced clinician in documenting the history of present illness. The first mentoring lesson Hancock discusses is from a time he felt stuck with his playing – his sound was routine. Miles Davis told him in a low husky murmur, ‘Don’t play the butter notes’. In medical education, ‘don’t play the butter notes’ suggests not undervaluing the metacognition and reflective aspects of medical training that need to be fostered during the early years of clinical teaching years

Faculty Recital, Darryl Harper, clarinet, Disc Two

Second Half of Performance Darryl Harper: Those Who Make Believ

Fusion of Wearable Kinetic and Kinematic Sensors to Estimate Triceps Surae Work during Outdoor Locomotion on Slopes

Muscle–tendon power output is commonly assessed in the laboratory through the work loop, a paired analysis of muscle force and length during a cyclic task. Work-loop analysis of muscle–tendon function in out-of-lab conditions has been elusive due to methodological limitations. In this work, we combined kinetic and kinematic measures from shear wave tensiometry and inertial measurement units, respectively, to establish a wearable system for estimating work and power output from the soleus and gastrocnemius muscles during outdoor locomotion. Across 11 healthy young adults, we amassed 4777 strides of walking on slopes from −10° to +10°. Results showed that soleus work scales with incline, while gastrocnemius work is relatively insensitive to incline. These findings agree with previous results from laboratory-based studies while expanding technological capabilities by enabling wearable analysis of muscle–tendon kinetics. Applying this system in additional settings and activities could improve biomechanical knowledge and evaluation of protocols in scenarios such as rehabilitation, device design, athletics, and military training

Wearable Tendon Kinetics

This study introduces a noninvasive wearable system for investigating tendon loading patterns during outdoor locomotion on variable terrain. The system leverages shear wave tensiometry, which is a new approach for assessing tendon load by tracking wave speed within the tissue. Our wearable tensiometry system uses a battery-operated piezoelectric actuator to induce micron-scale shear waves in a tendon. A data logger monitors wave propagation by recording from two miniature accelerometers mounted on the skin above the tendon. Wave speed is determined from the wave travel time between accelerometers. The wearable system was used to record Achilles tendon wave speed at 100 Hz during 1-km outdoor walking trials in nine young adults. Inertial measurement units (IMUs) simultaneously monitored participant position, walking speed, and ground incline. An analysis of 5108 walking strides revealed the coupled biomechanical effects of terrain slope and walking speed on tendon loading. Uphill slopes increased the tendon wave speed during push-off, whereas downhill slopes increased tendon wave speeds during early stance braking. Walking speed significantly modulated peak tendon wave speed on uphill slopes but had less influence on downhill slopes. Walking speed consistently induced greater early stance wave speeds for all slopes. These observations demonstrate that wearable shear wave tensiometry holds promise for evaluating tendon tissue kinetics in natural environments and uncontrolled movements. There are numerous practical applications of wearable tensiometry spanning orthopedics, athletics, rehabilitation, and ergonomics