Reversible, Specific, Active Aggregates of Endogenous Proteins Assemble upon Heat Stress.

Heat causes protein misfolding and aggregation and, in eukaryotic cells, triggers aggregation of proteins and RNA into stress granules. We have carried out extensive proteomic studies to quantify heat-triggered aggregation and subsequent disaggregation in budding yeast, identifying >170 endogenous proteins aggregating within minutes of heat shock in multiple subcellular compartments. We demonstrate that these aggregated proteins are not misfolded and destined for degradation. Stable-isotope labeling reveals that even severely aggregated endogenous proteins are disaggregated without degradation during recovery from shock, contrasting with the rapid degradation observed for many exogenous thermolabile proteins. Although aggregation likely inactivates many cellular proteins, in the case of a heterotrimeric aminoacyl-tRNA synthetase complex, the aggregated proteins remain active with unaltered fidelity. We propose that most heat-induced aggregation of mature proteins reflects the operation of an adaptive, autoregulatory process of functionally significant aggregate assembly and disassembly that aids cellular adaptation to thermal stress.

Motor control complexity can be dynamically simplified during gait pattern exploration using motor control-based biofeedback.

Understanding how the central nervous system coordinates diverse motor outputs has been a topic of extensive investigation. Although it is generally accepted that a small set of synergies underlies many common activities, such as walking, whether synergies are equally robust across a broader array of gait patterns or can be flexibly modified remains unclear. Here, we evaluated the extent to which synergies changed as nondisabled adults (n = 14) explored gait patterns using custom biofeedback. Secondarily, we used Bayesian additive regression trees to identify factors that were associated with synergy modulation. Participants explored 41.1 ± 8.0 gait patterns using biofeedback, during which synergy recruitment changed depending on the type and magnitude of gait pattern modification. Specifically, a consistent set of synergies was recruited to accommodate small deviations from baseline, but additional synergies emerged for larger gait changes. Synergy complexity was similarly modulated; complexity decreased for 82.6% of the attempted gait patterns, but distal gait mechanics were strongly associated with these changes. In particular, greater ankle dorsiflexion moments and knee flexion through stance, as well as greater knee extension moments at initial contact, corresponded to a reduction in synergy complexity. Taken together, these results suggest that the central nervous system preferentially adopts a low-dimensional, largely invariant control strategy but can modify that strategy to produce diverse gait patterns. Beyond improving understanding of how synergies are recruited during gait, study outcomes may also help identify parameters that can be targeted with interventions to alter synergies and improve motor control after neurological injury.NEW & NOTEWORTHY We used a motor control-based biofeedback system and machine learning to characterize the extent to which nondisabled adults can modulate synergies during gait pattern exploration. Results revealed that a small library of synergies underlies an array of gait patterns but that recruitment from this library changes as a function of the imposed biomechanical constraints. Our findings enhance understanding of the neural control of gait and may inform biofeedback strategies to improve synergy recruitment after neurological injury.

Audiovisual biofeedback amplifies plantarflexor adaptation during walking among children with cerebral palsy.

BACKGROUND: Biofeedback is a promising noninvasive strategy to enhance gait training among individuals with cerebral palsy (CP). Commonly, biofeedback systems are designed to guide movement correction using audio, visual, or sensorimotor (i.e., tactile or proprioceptive) cues, each of which has demonstrated measurable success in CP. However, it is currently unclear how the modality of biofeedback may influence user response which has significant implications if systems are to be consistently adopted into clinical care. METHODS: In this study, we evaluated the extent to which adolescents with CP (7M/1F; 14 [12.5,15.5] years) adapted their gait patterns during treadmill walking (6 min/modality) with audiovisual (AV), sensorimotor (SM), and combined AV + SM biofeedback before and after four acclimation sessions (20 min/session) and at a two-week follow-up. Both biofeedback systems were designed to target plantarflexor activity on the more-affected limb, as these muscles are commonly impaired in CP and impact walking function. SM biofeedback was administered using a resistive ankle exoskeleton and AV biofeedback displayed soleus activity from electromyography recordings during gait. At every visit, we measured the time-course response to each biofeedback modality to understand how the rate and magnitude of gait adaptation differed between modalities and following acclimation. RESULTS: Participants significantly increased soleus activity from baseline using AV + SM (42.8% [15.1, 59.6]), AV (28.5% [19.2, 58.5]), and SM (10.3% [3.2, 15.2]) biofeedback, but the rate of soleus adaptation was faster using AV + SM biofeedback than either modality alone. Further, SM-only biofeedback produced small initial increases in plantarflexor activity, but these responses were transient within and across sessions (p > 0.11). Following multi-session acclimation and at the two-week follow-up, responses to AV and AV + SM biofeedback were maintained. CONCLUSIONS: This study demonstrated that AV biofeedback was critical to increase plantarflexor engagement during walking, but that combining AV and SM modalities further amplified the rate of gait adaptation. Beyond improving our understanding of how individuals may differentially prioritize distinct forms of afferent information, outcomes from this study may inform the design and selection of biofeedback systems for use in clinical care.

Long-term effects of spasticity treatment, including selective dorsal rhizotomy, for individuals with cerebral palsy.

AIM: To understand the long-term effects of comprehensive spasticity treatment, including selective dorsal rhizotomy (SDR), on individuals with spastic cerebral palsy. METHOD: This was a pre-registered, multicenter, retrospectively matched cohort study. Children were matched on age range and spasticity at baseline. Children at one center underwent spasticity treatment including SDR (Yes-SDR, n=35) and antispastic injections. Children at two other centers had no SDR (No-SDR, n=40 total) and limited antispastic injections. All underwent subsequent orthopedic treatment. Participants returned for comprehensive long-term assessment (age ≥21y, follow-up ≥10y). Assessment included spasticity, contracture, bony alignment, strength, gait, walking energy, function, pain, stiffness, participation, and quality of life. RESULTS: Spasticity was effectively reduced at long-term assessment in the Yes-SDR group and was unchanged in the No-SDR group. There were no meaningful differences between the groups in any measure except the Gait Deviation Index (Yes-SDR + 11 vs No-SDR + 5) and walking speed (Yes-SDR unchanged, No-SDR declined 25%). The Yes-SDR group underwent more subsequent orthopedic surgery (11.9 vs 9.7 per individual) and antispastic injections to the lower limbs (14.4 vs <3, by design). INTERPRETATION: Untreated spasticity does not cause meaningful impairments in young adulthood at the level of pathophysiology, function, or quality of life.

Rectus femoris transfer in children with cerebral palsy: comparing a propensity score-matched observational study to a randomized controlled trial.

AIM: To test whether an observational study employing propensity score matching could accurately estimate the causal treatment effects of rectus femoris transfer (RFT) as part of single-event multilevel surgery (SEMLS) in ambulatory children with cerebral palsy. METHOD: We used a large clinical database to derive a propensity score for treatment assignment (SEMLS±RFT) and used this score to generate a matched patient cohort. We compared the causal treatment effects estimated from this matched cohort with a previously published randomized controlled trial (RCT). RESULTS: The treated arms of the observational study and RCT were well matched. There were 129 limbs (81 males) with a mean age of 10 years 7 months (4y 7mo) in the treated arm of the observational study, and 129 limbs (68 males) with a mean age of 10 years 2 months (3y 9mo) in the control arm of the observational study. Differences between the observational study and RCT cohorts were clinically meaningless for knee flexion kinematics (1-4°), timing of knee angle extrema (<3% gait cycle), and speed (<5mm/s). Postoperative changes in the observational study matched those from the RCT. All but one of the observational study confidence intervals were completely contained within the corresponding RCT confidence interval; there were no meaningful differences in magnitude or sign of key outcomes related to stiff knee gait. INTERPRETATION: Propensity score matching is an accurate method for estimating the causal treatment effects of RFT as part of an SEMLS. It seems reasonable to extend this approach to other common components of SEMLS treatment in this population. WHAT THIS PAPER ADDS: Propensity score matching is an accurate method for estimating the causal treatment effects of rectus femoris transfer (RFT) in ambulatory children with cerebral palsy (CP). The causal treatment effects for RFT surgery in ambulatory children diagnosed with CP were validated.

Comparing short-term outcomes between conus medullaris and cauda equina surgical techniques of selective dorsal rhizotomy.

AIM: To compare short-term outcomes between conus medullaris (conus) and cauda equina (cauda) selective dorsal rhizotomy (SDR) techniques in children with spastic cerebral palsy. METHOD: This was a retrospective review of SDR at a single center from 2013 to 2017. Gait and functional outcome measures were assessed at no more than 18 months pre-SDR (baseline) and 8 to 36 months post-SDR (follow-up). Transient complications during inpatient stay were quantified. RESULTS: In total, 21 and 59 children underwent conus and cauda SDR respectively. Ashworth Scale scores were nearly normalized at follow-up. Most physical examination and functional measures exhibited similar baseline to follow-up responses for both groups. From baseline to follow-up, sagittal plane knee kinematics for both groups significantly improved (p<0.01) by 11° at initial contact, 9° to 10° in stance phase, and 4° in swing phase. Sagittal plane ankle kinematics improved more for the cauda group than the conus group in both stance phase (10° vs 2°, p<0.01) and swing phase (13° vs 3°, p<0.01). Post-surgical complications were similar between groups. INTERPRETATION: Conus and cauda SDR techniques resulted in similar short-term outcomes except in ankle kinematics at follow-up. The cauda group exhibited a large improvement towards dorsiflexion, while there was residual equinus in the conus group despite Ashworth Scale scores normalizing equally in both groups. WHAT THIS PAPER ADDS: Conus and cauda selective dorsal rhizotomy (SDR) resulted in mostly similar short-term gait and functional outcomes. Conus SDR resulted in residual equinus dynamically, despite normalized spasticity measures. Post-surgical complications were mostly similar between SDR techniques.

Queuosine modification protects cognate tRNAs against ribonuclease cleavage.

Eukaryotic transfer RNAs (tRNA) contain on average 13 modifications that perform a wide range of roles in translation and in the generation of tRNA fragments that regulate gene expression. Queuosine (Q) modification occurs in the wobble anticodon position of tRNAs for amino acids His, Asn, Tyr, and Asp. In eukaryotes, Q modification is fully dependent on diet or on gut microbiome in multicellular organisms. Despite decades of study, cellular roles of Q modification remain to be fully elucidated. Here we show that in human cells, Q modification specifically protects its cognate tRNAHis and tRNAAsn against cleavage by ribonucleases. We generated cell lines that contain completely depleted or fully Q-modified tRNAs. Using these resources, we found that Q modification significantly reduces angiogenin cleavage of its cognate tRNAs in vitro. Q modification does not change the cellular abundance of the cognate full-length tRNAs, but alters the cellular content of their fragments in vivo in the absence and presence of stress. Our results provide a new biological aspect of Q modification and a mechanism of how Q modification alters small RNA pools in human cells.

Energy consumption does not change after selective dorsal rhizotomy in children with spastic cerebral palsy.

AIM: To determine whether energy consumption changes after selective dorsal rhizotomy (SDR) among children with cerebral palsy (CP). METHOD: We retrospectively evaluated net nondimensional energy consumption during walking among 101 children with bilateral spastic CP who underwent SDR (59 males, 42 females; median age [5th centile, 95th centile] 5y 8mo [4y 2mo, 9y 4mo]) compared to a control group of children with CP who did not undergo SDR. The control group was matched by baseline age, spasticity, and energy consumption (56 males, 45 females; median age [5th centile, 95th centile] 5y 8mo [4y 1mo, 9y 6mo]). Outcomes were compared at baseline and follow-up (SDR: mean [SD] 1y 7mo [6mo], control: 1y 8mo [8mo]). RESULTS: The SDR group had significantly greater decreases in spasticity compared to matched controls (-42% SDR vs -20% control, p<0.001). While both groups had a modest reduction in energy consumption between visits (-12% SDR, -7% control), there was no difference in change in energy consumption (p=0.11) or walking speed (p=0.56) between groups. INTERPRETATION: The SDR group did not exhibit greater reductions in energy consumption compared to controls. The SDR group had significantly greater spasticity reduction, suggesting that spasticity had minimal impact on energy consumption during walking in CP. These results support prior findings that spasticity and energy consumption decrease with age in CP. Identifying matched control groups is critical for outcomes research involving children with CP to account for developmental changes.

Function and origin of mistranslation in distinct cellular contexts.

Mistranslation describes errors during protein synthesis that prevent the amino acid sequences specified in the genetic code from being reflected within proteins. For a long time, mistranslation has largely been considered an aberrant cellular process that cells actively avoid at all times. However, recent evidence has demonstrated that cells from all three domains of life not only tolerate certain levels and forms of mistranslation, but actively induce mistranslation under certain circumstances. To this end, dedicated biological mechanisms have recently been found to reduce translational fidelity, which indicates that mistranslation is not exclusively an erroneous process and can even benefit cells in particular cellular contexts. There currently exists a spectrum of mistranslational processes that differ not only in their origins, but also in their molecular and cellular effects. These findings suggest that the optimal degree of translational fidelity largely depends on a specific cellular context. This review aims to conceptualize the basis and functional consequence of the diverse types of mistranslation that have been described so far.

Ground reaction and solid ankle-foot orthoses are equivalent for the correction of crouch gait in children with cerebral palsy.

AIM: To investigate any performance differences between the solid ankle-foot orthosis (SAFO) and ground reaction ankle-foot orthosis (GRAFO) designs for correcting crouch gait in children diagnosed with cerebral palsy (CP). METHOD: We retrospectively analyzed 147 individuals seen at our center who: (1) were diagnosed with diplegic CP, (2) walked with crouch gait, (3) had bilateral SAFO or GRAFO prescription, and (4) had three-dimensional gait analysis collected for both barefoot and orthosis walking conditions. RESULTS: Overall, no performance gap was identified between the SAFO and GRAFO groups (p=0.828). A series of bootstrapped stepwise regression analyses indicated that ankle-foot orthosis (AFO) design was not predictive of crouch gait improvements. Improvements in crouch gait were instead shown to be predicted by AFO neutral angle and four patient factors: amount of dorsiflexion in stance, level of knee flexion contracture, age, and severity of crouch. INTERPRETATION: Our results show that the SAFO and GRAFO designs are equally effective at correcting crouch gait for individuals diagnosed with CP. WHAT THIS PAPER ADDS: No performance difference was detected between solid ankle-foot orthoses and ground reaction ankle-foot orthoses designs for crouch gait correction. Crouch gait improvement from ankle-foot orthoses (AFO) is influenced by AFO neutral angle. Other factors of influence include: dorsiflexion in stance, level of knee flexion contracture, age, and severity of crouch.

Muscle synergies demonstrate only minimal changes after treatment in cerebral palsy.

BACKGROUND: Children with cerebral palsy (CP) have altered synergies compared to typically-developing peers, reflecting different neuromuscular control strategies used to move. While these children receive a variety of treatments to improve gait, whether synergies change after treatment, or are associated with treatment outcomes, remains unknown. METHODS: We evaluated synergies for 147 children with CP before and after three common treatments: botulinum toxin type-A injection (n = 52), selective dorsal rhizotomy (n = 38), and multi-level orthopaedic surgery (n = 57). Changes in synergy complexity were measured by the number of synergies required to explain > 90% of the total variance in electromyography data and total variance accounted for by one synergy. Synergy weights and activations before and after treatment were compared using the cosine similarity relative to average synergies of 31 typically-developing (TD) peers. RESULTS: There were minimal changes in synergies after treatment despite changes in walking patterns. Number of synergies did not change significantly for any treatment group. Total variance accounted for by one synergy increased (i.e., moved further from TD peers) after botulinum toxin type-A injection (1.3%) and selective dorsal rhizotomy (1.9%), but the change was small. Synergy weights did not change for any treatment group (average 0.001 ± 0.10), but synergy activations after selective dorsal rhizotomy did change and were less similar to TD peers (- 0.03 ± 0.07). Only changes in synergy activations were associated with changes in gait kinematics or walking speed after treatment. Children with synergy activations more similar to TD peers after treatment had greater improvements in gait. CONCLUSIONS: While many of these children received significant surgical procedures and prolonged rehabilitation, the minimal changes in synergies after treatment highlight the challenges in altering neuromuscular control in CP. Development of treatment strategies that directly target impaired control or are optimized to an individual's unique control may be required to improve walking function.

Determining the fidelity of tRNA aminoacylation via microarrays.

The fidelity of tRNA aminoacylation is a critical determinant for the ultimate accuracy of protein synthesis. Although aminoacyl-tRNA synthetases are assumed to consistently maintain high tRNA charging fidelity, recent evidence has demonstrated that the fidelity of the aminoacylation reaction can be actively regulated and liable to change. Accordingly, the ability to conveniently assay the fidelity of tRNA charging is becoming increasingly relevant for studying mistranslation. Here we describe a combined radioactivity and microarray based method that can quantitatively elucidate which individual cognate or noncognate tRNA isoacceptors are charged with amino acid. In this technique, in vitro tRNA charging reactions or in vivo pulse-labeling is performed using a radiolabeled amino acid and tRNA microarrays are used to distinguish tRNA isoacceptors in total tRNA. During the tRNA array hybridization, each tRNA will hybridize to its unique probe and subsequent phosphorimaging of the array can determine which tRNAs were aminoacylated with the radiolabeled amino acid. The method can be used to assess the fidelity of tRNA charging in vivo or in vitro and can be applied to any organism with annotated tRNA genes.

Associations Between Muscle Synergies and Treatment Outcomes in Cerebral Palsy Are Robust Across Clinical Centers.

OBJECTIVE: To determine whether patient-specific differences in motor control quantified using muscle synergy analysis were associated with changes in gait after treatment of cerebral palsy (CP) across 2 clinical centers with different treatments and clinical protocols. DESIGN: Retrospective cohort study. SETTING: Clinical medical center. PARTICIPANTS: Center 1: children with CP (n=473) and typically developing (TD) children (n=84). Center 2: children with CP (n=163) and TD children (n=12). INTERVENTIONS: Standard clinical care at each center. MAIN OUTCOME MEASURES: The Dynamic Motor Control Index During Walking (walk-DMC) was computed from electromyographic data during gait using muscle synergy analysis. Regression analysis was used to evaluate whether pretreatment walking speed or kinematics, muscle synergies, treatment group, prior treatment, or age were associated with posttreatment changes in gait at both clinical centers. RESULTS: Walk-DMC was significantly associated with changes in speed and kinematics after treatment with similar regression models at both centers. Children with less impaired motor control were more likely to have improvements in walking speed and gait kinematics after treatment, independent of treatment group. CONCLUSIONS: Dynamic motor control evaluated with synergy analysis was associated with changes in gait after treatment at both centers, despite differences in treatments and clinical protocols. This study further supports the finding that walk-DMC provides additional information, not captured in traditional gait analysis, that may be useful for treatment planning.

Temperature dependent mistranslation in a hyperthermophile adapts proteins to lower temperatures.

All organisms universally encode, synthesize and utilize proteins that function optimally within a subset of growth conditions. While healthy cells are thought to maintain high translational fidelity within their natural habitats, natural environments can easily fluctuate outside the optimal functional range of genetically encoded proteins. The hyperthermophilic archaeon Aeropyrum pernix (A. pernix) can grow throughout temperature variations ranging from 70 to 100°C, although the specific factors facilitating such adaptability are unknown. Here, we show that A. pernix undergoes constitutive leucine to methionine mistranslation at low growth temperatures. Low-temperature mistranslation is facilitated by the misacylation of tRNA(Leu) with methionine by the methionyl-tRNA synthetase (MetRS). At low growth temperatures, the A. pernix MetRS undergoes a temperature dependent shift in tRNA charging fidelity, allowing the enzyme to conditionally charge tRNA(Leu) with methionine. We demonstrate enhanced low-temperature activity for A. pernix citrate synthase that is synthesized during leucine to methionine mistranslation at low-temperature growth compared to its high-fidelity counterpart synthesized at high-temperature. Our results show that conditional leucine to methionine mistranslation can make protein adjustments capable of improving the low-temperature activity of hyperthermophilic proteins, likely by facilitating the increasing flexibility required for greater protein function at lower physiological temperatures.

Global tRNA misacylation induced by anaerobiosis and antibiotic exposure broadly increases stress resistance in Escherichia coli.

High translational fidelity is commonly considered a requirement for optimal cellular health and protein function. However, recent findings have shown that inducible mistranslation specifically with methionine engendered at the tRNA charging level occurs in mammalian cells, yeast and archaea, yet it was unknown whether bacteria were capable of mounting a similar response. Here, we demonstrate that Escherichia coli misacylates non-methionyl-tRNAs with methionine in response to anaerobiosis and antibiotic exposure via the methionyl-tRNA synthetase (MetRS). Two MetRS succinyl-lysine modifications independently confer high tRNA charging fidelity to the otherwise promiscuous, unmodified enzyme. Strains incapable of tRNA mismethionylation are less adept at growth in the presence of antibiotics and stressors. The presence of tRNA mismethionylation and its potential role in mistranslation within the bacterial domain establishes this response as a pervasive biological mechanism and connects it to diverse cellular functions and modes of fitness.

tRNA Misacylation with Methionine in the Mouse Gut Microbiome in Situ.

Global protein mistranslation with methionine has been shown to be a conserved biological process that affords distinct functional advantages in all three domains of life. In all instances, methionine mistranslation occurs through a regulated process where low-fidelity forms of methionyl-tRNA synthetase are conditionally induced to mischarge non-methionyl-tRNAs with methionine followed by the utilization of the misacylated tRNAs in translation. In mammals, methionine mistranslation contributes to oxidative stress response; in the hyperthermophilic archaeon Aeropyrum pernix, methionine mistranslation produces proteins that are better adapted to low temperature growth; in E. coli, methionine mistranslation increases resistance to antibiotics and chemical stressors. The phenotypic benefits conferred by tRNA mismethionylation suggest that it should be a widespread adaptational mechanism in diverse bacterial lineages, yet this response has only been described in E. coli. Furthermore, previous microbial investigations on this response have been confined to axenic laboratory cultures. It was unknown whether tRNA mismethionylation was relevant in a natural microbial habitat. Here we show that four abundant gut microbiotal genera belonging to the Firmicutes and Bacteroidetes phyla perform constitutive tRNA misacylation with methionine in the mouse cecum in situ. These results reveal the ubiquity of the tRNA mismethionylation process among bacteria and implicate the potential importance of this response for subsistence and adaptation in natural habitats.

Changes in hip abductor moment 3 or more years after femoral derotation osteotomy among individuals with cerebral palsy.

AIM: To examine the effect of femoral derotation osteotomy (FDO) on dimensionless hip abductor moment during gait in children with cerebral palsy. METHODS: We retrospectively analyzed data from independent ambulators within our database. Postoperative visits 1 year (short-term) and at least 3 years (mid-term) were analyzed. We estimated the coronal plane hip abductor moment arm based on musculoskeletal modeling that accounted for anteversion and hip rotation. RESULTS: There were 140 individuals with a short-term analysis (77 males, 63 females; age at surgery 9y 11mo [range 4y 5mo-17y 5mo]) and 29 with mid-term analysis (15 males, 14 females; age at surgery 8y 7mo [range 4y 5mo-13y 1mo]). At short-term, anteversion and internal hip rotation decreased 35° and 13° respectively, which increased median (IQR) moment arms from 20 (23) per cent below normal to 2 (12) per cent above normal. Dimensionless mean hip abductor moment remained unchanged at short-term. Mid-term anteversion did not change but hip rotation increased 8° and hip abductor moment increased to 0.040 (0.029). There was no change in pelvic and trunk obliquity, although hip abductor strength increased and walking velocity decreased at mid-term. INTERPRETATION: The unexpected lack of improvement in hip abductor moment from pre- to short-term may be caused by gait compensations that unload the hip. The increase in hip abductor moment beyond 3 years postoperatively underscores the benefits of an FDO into adolescence for independent ambulating individuals with cerebral palsy.

Long-term outcomes after selective dorsal rhizotomy: a retrospective matched cohort study.

AIM: To examine long-term outcomes of selective dorsal rhizotomy (SDR) 10 to 17 years after surgery. METHOD: Participants who underwent SDR had spastic diplegic cerebral palsy (CP), completed baseline gait analysis, and were 16 to 25 years old at follow-up. Non-SDR participants (i.e. controls) were matched on important clinical parameters at baseline but did not undergo SDR. All study participants completed six surveys assessing pain, quality of life, participation, function, and mobility. Treatment history for lower extremity surgery and antispasticity injections was tabulated. A subset of each study group returned for three-dimensional gait analysis, including kinematics, metabolic energy cost, and physical examination. Gait Deviation Index (GDI) was calculated to measure gait quality. RESULTS: The study cohort had 24 participants with SDR and 11 without SDR. Of these, 13 patients with SDR (five males, eight females; median [IQR] age 17y 2mo [16y 8mo-17y 9mo]) and eight without SDR (three males, five females; median [IQR] age 19y 2mo [17y 3mo-21y 11mo]) completed baseline and follow-up gait analysis. Spasticity significantly decreased in those with SDR (p<0.05). Gait Deviation Index improved more in participants without SDR than those with SDR (Δnon-SDR =12.8 vs ΔSDR =9.1; p=0.01). Compared with the SDR group, participants without SDR underwent significantly more subsequent interventions (p<0.05). INTERPRETATION: Patients in both the SDR and non-SDR groups showed improved gait quality more than 10 years after surgery. Participants without SDR had a larger improvement in gait pathology but underwent significantly more intervention. There were no differences between groups in survey measures. These results suggest differing treatment courses provide similar outcomes into early adulthood. WHAT THIS PAPER ADDS: Selective dorsal rhizotomy (SDR) and non-SDR groups had significant improvement in gait pathology over time. The non-SDR group had significantly better gait compared with the SDR group at follow-up. The groups had similar levels of energy cost, pain, and quality of life. Non-SDR participants underwent significantly more orthopaedic surgery and antispasticity injections than SDR participants. Use of a clinically similar control group highlights that different treatment courses may result in similar outcomes into young adulthood.

Deficits in functional performance and gait one year after total knee arthroplasty despite improved self-reported function.

PURPOSE: The current literature lacks sufficient information about improvements in gait patterns and function after total knee arthroplasty (TKA) and whether patients return to full function. This study evaluated change in gait, performance-based function, and self-reported function 1 year after TKA in patients with symptomatic knee osteoarthritis and how these aspects interrelate. METHODS: A total of 28 patients (64 % female) with knee osteoarthritis, with a mean age of 66 (±7) years, and 25 age- and gender-matched controls participated in this prospective cohort study. Three-dimensional gait analysis generated comprehensive measures of kinematic and kinetic gait deviations, respectively. Participants completed the Five Times Sit-to-Stand (5STS) test, and the self-reported questionnaire Knee Injury and Osteoarthritis Outcome Score (KOOS), at baseline prior to surgery and 1 year after TKA. RESULTS: Kinetic gait deviations of both the operated and non-operated limb persisted in patients with knee osteoarthritis at 1 year after surgery, while kinematic gait patterns were comparable to controls. Performance on the 5STS and KOOS scores in patients with knee osteoarthritis improved significantly 1 year after surgery (effect size 0.5-1.5), but did not reach the level of controls. Ten patients with knee osteoarthritis (36 %) exceeded the minimally detectable change on the 5STS. CONCLUSION: Measures of overall gait patterns and the 5STS revealed improvements in function 1 year after TKA, but were not restored to the level of healthy controls. Based on change in 5STS performance, we identified patients with substantial improvements in gait patterns. Self-reported measures of function could not detect differences between patients improving in 5STS performance and those who did not. These findings highlight the use of the 5STS in clinical practice since improvement on this test seems to follow the reduction in gait pattern deviations. LEVEL OF EVIDENCE: II.

Selective Enzymatic Demethylation of N2 ,N2 -Dimethylguanosine in RNA and Its Application in High-Throughput tRNA Sequencing.

The abundant Watson-Crick face methylations in biological RNAs such as N1 -methyladenosine (m1 A), N1 -methylguanosine (m1 G), N3 -methylcytosine (m3 C), and N2 ,N2 -dimethylguanosine (m22 G) cause significant obstacles for high-throughput RNA sequencing by impairing cDNA synthesis. One strategy to overcome this obstacle is to remove the methyl group on these modified bases prior to cDNA synthesis using enzymes. The wild-type E. coli AlkB and its D135S mutant can remove most of m1 A, m1 G, m3 C modifications in transfer RNA (tRNA), but they work poorly on m22 G. Here we report the design and evaluation of a series of AlkB mutants against m22 G-containing model RNA substrates that we synthesize using an improved synthetic method. We show that the AlkB D135S/L118V mutant efficiently and selectively converts m22 G modification to N2 -methylguanosine (m2 G). We also show that this new enzyme improves the efficiency of tRNA sequencing.