Otoplasty: The Belfast Experience. A 10-Year Review of 2333 Ear Outcomes.

BACKGROUND: "Prominent ear" remains one of the most common referrals to pediatric plastic surgery. The perceived deformity has been corrected using a multitude of techniques for over a century, and significant variation in practice still exists. Recent studies suggesting that cartilage-scoring techniques are associated with more major complications than suture techniques may have led to an adverse international perception of the technique. Thus, waning use of anterior scoring prominent ear correction appears to be occurring. For appropriate cases, the authors have used anterior scoring for over 20 years, with high patient satisfaction and low complication rates. They present a review of all cases and outcomes from 2005 to 2015. The authors believe this is the largest case series of anterior scoring otoplasty published to date. METHODS: All pediatric cases undergoing prominent ear correction from 2005 to 2015 were included in this retrospective case note analysis and follow-up study. Patient demographics, operative details including early and late complications, and postoperative results were analyzed. METHODS: Over a 10-year period, 1199 otoplasties were performed (1134 bilateral, 65 unilateral), for a total of 2333 ear corrections. A total of 1575 ears were corrected using the anterior scoring technique. The remaining cases underwent correction by means of suture only, cartilage reduction, or combination techniques. There was a significantly lower all-cause reoperation rate for anterior scoring compared to suture-only techniques ( P = 0.0039; significant at P < 0.025). There were no reported cases of cartilage necrosis. CONCLUSIONS: This study demonstrates that in appropriately selected patients, anterior scoring otoplasty is a low-morbidity procedure. In the authors' institution, when compared to suture techniques, it was associated with a lower rate of complications and reoperation rate than suture-only techniques. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, IV.

Complete transection of the sciatic nerve following closed femoral fracture.

Complete transection of the sciatic nerve following femoral fracture is extremely rare. In the setting of closed injury it has only been reported in two other cases. Here we present a teenage motorcyclist who sustained a closed left, mid-femoral fracture following a road traffic collision with complete transection of the sciatic nerve. Despite being a closed injury, the obvious limb deformity of the patient and extreme pain prompted immediate nerve block during the primary survey making formal neurological assessment difficult. This case highlights the possibility of complete major nerve transection in closed injuries, and the importance of careful clinical examination alongside repeat imaging.

A review of functional latissimus dorsi transfers for absent elbow flexion and supination.

AIMS: To review patients treated with a functional latissimus dorsi flap for congenital and acquired elbow flexion deficits. METHODS: Retrospective review of functional latissimus dorsi flaps performed in one regional unit. Patient notes were reviewed to determine aetiology, pre-op deficits and function, surgical technique, complications and outcomes. RESULTS: A total of six functional latissimus dorsi transfers were performed on four patients. Two patients had bilateral latissimus dorsi transfers for congenital defects. The remaining two procedures were for traumatic defects. Post-operatively both children had excellent outcomes with full range of active movement allowing them to perform key activities of daily living. SURGICAL TECHNIQUE: Epimysium of latissimus dorsi folded to form a pseudo-tendon, tunnelled subcutaneously and either attached to a remnant of biceps tendon or secured to the radius. Congenital patients achieved better outcomes; pre-operatively, there was no active elbow flexion in all four elbows but 90-100 of passive flexion. COMPLICATIONS: One latissimus dorsi dehiscence which required revision surgery. Two donor-site seromas. CONCLUSIONS: Functional latissimus dorsi transfer has been shown to achieve excellent elbow flexion in patients with congenital absence of biceps and brachialis muscles. Outcomes in older patients with traumatic injuries have been less successful in achieving a full range of active flexion.

A constant harvest technique for chimeric anterolateral thigh flaps and patient outcomes following their use in reconstructive head and neck surgery.

BACKGROUND: Chimeric anterolateral thigh free flaps (ALT) have been commonly used for head and neck defects, which require two epithelial lined surfaces. However, because of unpredictable vascular anatomy, it is a challenge to consistently elevate large chimeric flaps with multiple perforators based on the Lateral Circumflex Femoral Artery (LCFA). Here, we present our method to reliably harvest a chimeric flap from the ALT territory and investigate its long-term outcomes when used in the reconstruction of extensive head and neck defects. METHODS: A prospective review of practice consisting of 27 patients, between January 2011 and April 2019, with extensive through-and-through head and neck defects, which require dual paddle flaps underwent reconstruction with chimeric ALT harvested with a portion of distal vastus lateralis. The age of the patients ranged from 32 to 68 years (mean 53.2 years). RESULTS: Flap length ranged from 17 to 30 cm (mean, 25.6 cm). The mean flap area was 261.6 cm2 (range, from 225 to 340 cm2). The mean ischemia time was 162.9 min (range, from 59 to 269 min). At a mean follow-up time of 33.4 months (range, from 4 to 91 months), four patients died of cancer recurrence. For the other 23 patients, 4 required revision to achieve better cosmetic lip competence. All flaps survived with two recorded returns to theater for pedicle exploration associated with partial flap loss only. CONCLUSION: Harvesting the chimeric ALT with a portion of vastus lateralis distally negates the need for tenuous intramuscular perforator dissection. It is a reliable option for head and neck surgery, which require composite reconstruction. Using this technique produces a good functional cosmetic outcome. It also allows large defects to be reconstructed in a single sitting with free tissue transfer.

A Novel, Modified Human Butyrylcholinesterase Catalytically Degrades the Chemical Warfare Nerve Agent, Sarin.

Chemical warfare nerve agents (CWNAs) present a global threat to both military and civilian populations. The acute toxicity of CWNAs stems from their ability to effectively inhibit acetylcholinesterase (AChE). This inhibition can lead to uncontrolled cholinergic cellular signaling, resulting in cholinergic crisis and, ultimately, death. Although the current FDA-approved standard of care is moderately effective when administered early, development of novel treatment strategies is necessary. Butyrylcholinesterase (BChE) is an enzyme which displays a high degree of structural homology to AChE. Unlike AChE, the roles of BChE are uncertain and possibilities are still being explored. However, BChE appears to primarily serve as a bioscavenger of toxic esters due to its ability to accommodate a wide variety of substrates within its active site. Like AChE, BChE is also readily inhibited by CWNAs. Due to its high affinity for binding CWNAs, and that null-BChE yields no apparent health effects, exogenous BChE has been explored as a candidate therapeutic for CWNA intoxication. Despite years of research, minimal strides have been made to develop a catalytic bioscavenger. Furthermore, BChE is only in early clinical trials as a stoichiometric bioscavenger of CWNAs, and large quantities must be administered to treat CWNA toxicity. Here, we describe previously unidentified mutations to residues within and adjacent to the acyl binding pocket (positions 282-285 were mutagenized from YGTP to NHML) of BChE that confer catalytic degradation of the CWNA, sarin. These mutations, along with corresponding future efforts, may finally lead to a novel therapeutic to combat CWNA intoxication.

Characterization of Cholinesterases From Multiple Large Animal Species for Medical Countermeasure Development Against Chemical Warfare Nerve Agents.

Organophosphorus (OP) compounds, which include insecticides and chemical warfare nerve agents (CWNAs) such as sarin (GB) and VX, continue to be a global threat to both civilian and military populations. It is widely accepted that cholinesterase inhibition is the primary mechanism for acute OP toxicity. Disruption of cholinergic function through the inhibition of acetylcholinesterase (AChE) leads to the accumulation of the neurotransmitter acetylcholine. Excess acetylcholine at the synapse results in an overstimulation of cholinergic neurons which manifests in the common signs and symptoms of OP intoxication (miosis, increased secretions, seizures, convulsions, and respiratory failure). The primary therapeutic strategy employed in the United States to treat OP intoxication includes reactivation of inhibited AChE with the oxime pralidoxime (2-PAM) along with the muscarinic acetylcholine receptor antagonist atropine and the benzodiazepine, diazepam. CWNAs are also known to inhibit butyrylcholinesterase (BChE) without any apparent toxic effects. Therefore, BChE may be viewed as a "bioscavenger" that stoichiometrically binds CWNAs and removes them from circulation. The degree of inhibition of AChE and BChE and the effectiveness of 2-PAM are known to vary among species. Animal models are imperative for evaluating the efficacy of CWNA medical countermeasures, and a thorough characterization of available animal models is important for translating results to humans. Thus, the objective of this study was to compare the circulating levels of each of the cholinesterases as well as multiple kinetic properties (inhibition, reactivation, and aging rates) of both AChE and BChE derived from humans to AChE and BChE derived from commonly used large animal models.

Kinetic analysis of oxime-assisted reactivation of human, Guinea pig, and rat acetylcholinesterase inhibited by the organophosphorus pesticide metabolite phorate oxon (PHO).

Phorate is a highly toxic agricultural pesticide currently in use throughout the world. Like many other organophosphorus (OP) pesticides, the primary mechanism of the acute toxicity of phorate is acetylcholinesterase (AChE) inhibition mediated by its bioactivated oxon metabolite. AChE reactivation is a critical aspect in the treatment of acute OP intoxication. Unfortunately, very little is currently known about the capacity of various oximes to rescue phorate oxon (PHO)-inhibited AChE. To help fill this knowledge gap, we evaluated the kinetics of inhibition, reactivation, and aging of PHO using recombinant AChE derived from three species (rat, guinea pig and human) commonly utilized to study the toxicity of OP compounds and five oximes that are currently fielded (or have been deemed extremely promising) as anti-OP therapies by various nations around the globe: 2-PAM Cl, HI-6 DMS, obidoxime Cl2, MMB4-DMS, and HLö7 DMS. The inhibition rate constants (ki) for PHO were calculated for AChE derived from each species and found to be low (i.e., 4.8×103 to 1.4×104M-1min-1) compared to many other OPs. Obidoxime Cl2 was the most effective reactivator tested. The aging rate of PHO-inhibited AChE was very slow (limited aging was observed out to 48h) for all three species. CONCLUSIONS: (1) Obidoxime Cl2 was the most effective reactivator tested. (2) 2-PAM Cl, showed limited effectiveness in reactivating PHO-inhibited AChE, suggesting that it may have limited usefulness in the clinical management of acute PHO intoxication. (3) The therapeutic window for oxime administration following exposure to phorate (or PHO) is not limited by aging.

Punishment Attacks in Post-Ceasefire Northern Ireland: An Emergency Department Perspective.

Northern Ireland (NI) has been in a post-conflict state for over twenty years. However, injuries sustained during paramilitary Punishment Attacks (PA) remain a common hospital presentation. The aim of this study was to compare the current province-wide frequency and cost with data collected from the same unit in 1994, the end of the so called, "Troubles". A ten month retrospective emergency chart analysis from all assault and gunshot wound (GSW) attendances to the Emergency Department, Royal Victoria Hospital Belfast (RVH) in 2012 was carried out. Age, sex, injury type, treatment outcome and associated cost of PA was documented. During the study period we recorded a total of thirty two PAs. Twenty seven were the result of gunshot wounds (GSWs), while five were assaults (punishment beatings). Seventeen required admission for definitive management. Nine cases required orthopaedic intervention, two required plastic surgery, two required maxillofacial input and one case required vascular surgery. All but two of those involved were male. Mean age of individuals admitted was 27.47. Total cost of patients both admitted and managed in the Emergency Department (ED) amounted to £91,362. On comparison with 1994, there are more PA presentations. Due to changing wound characteristics and evolving management overall cost is however less.

Efficacy of Recommended Prehospital Human Equivalent Doses of Atropine and Pralidoxime Against the Toxic Effects of Carbamate Poisoning in the Hartley Guinea Pig.

PURPOSE: Aldicarb and methomyl are carbamate pesticides commonly implicated in human poisonings. The primary toxic mechanism of action for carbamate poisoning is cholinesterase (ChE) inhibition. As such, it is logical to assume that the currently accepted therapies for organophosphate poisoning (muscarinic antagonist atropine and the oxime acetylcholinesterase reactivator pralidoxime chloride [2-PAM Cl]) could afford therapeutic protection. However, oximes have been shown to be contraindicated for poisoning by some carbamates. METHODS: A protective ratio study was conducted in guinea pigs to evaluate the efficacy of atropine and 2-PAM Cl. The ChE activity was determined in both the blood and the cerebral cortex. RESULTS: Coadministration of atropine free base (0.4 mg/kg) and 2-PAM Cl (25.7 mg/kg) demonstrated protective ratios of 2 and 3 against aldicarb and methomyl, respectively, relative to saline. The data reported here show that this protection was primarily mediated by the action of atropine. The reactivator 2-PAM Cl had neither positive nor negative effects on survival. Both blood acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) activities were significantly reduced at 15 minutes postchallenge but gradually returned to normal within 24 hours. Analysis of cerebral cortex showed that BChE, but not AChE, activity was reduced in animals that succumbed prior to 24 hours after challenge. CONCLUSION: The results suggest that coadministration of atropine and 2-PAM Cl at the currently recommended human equivalent doses for use in the prehospital setting to treat organophosphorus nerve agent and pesticide poisoning would likely also be effective against aldicarb or methomyl poisoning.

Acute toxicity of phorate oxon by oral gavage in the Sprague-Dawley rat.

The oral toxicity of phorate oxon (PHO), with emphasis on gender- and age-related effects, was characterized in the Sprague-Dawley rat. The oral LD50 (95% fiducial limits) for PHO in corn oil was 0.88 (0.79, 1.04) mg/kg in males and 0.55 (0.46, 0.63) mg/kg in females with a probit slope of 15. Females had higher baseline blood cholinesterase titers, but males were significantly more tolerant. Younger rats generally had lower absolute cholinesterase blood titers. However as PHO challenges increased, baseline-normalized cholinesterase inhibition was independent of age and gender. Butyrylcholinesterase (BChE) and especially acetylcholinesterase (AChE) in brains of younger females were affected more than that in either males or older females. In summary, while female rats, especially older females, had higher titers relative to males, female rats were more susceptible in terms of absolute cholinesterase inhibition and 24-hr lethality data, but the differences were not observed when titers were normalized to baseline levels.

Evaluation of HemogloBind™ treatment for preparation of samples for cholinesterase analysis.

Acetylcholine is an essential neurotransmitter found throughout the nervous system. Its action on postsynaptic receptors is regulated through hydrolysis by various carboxylesterases, especially cholinesterases (ChEs). The acute toxicity of organophosphate (OP) compounds is directly linked to their action as inhibitors of ChE. One widely used assay for evaluating ChE activity is a spectrophotometric method developed by Ellman et al. When the enzyme source is from tissues or, in particular, blood, hemoglobin displays a spectrophotometric peak at the same wavelength used to analyze cholinergic activity. This creates a substantial background that interferes with the Ellman's assay and must be overcome in order to accurately monitor cholinesterase activity. Herein, we directly compare blood processing methods: classical method (1.67 ± 0.30 U/mL) and HemogloBind™ treatment (1.51 ± 0.17 U/mL), and clearly demonstrate that pretreatment of blood samples with Hemoglobind™ is both a sufficient and rapid sample preparation method for the assessment of ChE activity using the Ellman's method.

Mutational analysis reveals Escherichia coli oriC interacts with both DnaA-ATP and DnaA-ADP during pre-RC assembly.

Prior to initiating DNA synthesis, Escherichia coli oriC switches from ORC, comprising initiator DnaA bound at three high-affinity sites, to pre-RC, when additional DnaA molecules interact with low-affinity sites. Two types of low-affinity sites exist: R boxes that bind DnaA-ATP and DnaA-ADP with equal affinity, and I-sites with a three- to fourfold preference for DnaA-ATP. To assess the regulatory role of weak DnaA interactions during pre-RC assembly in vivo, we compared the behaviour of plasmid-borne wild-type oriC with mutants having an increased or decreased number of DnaA-ATP discriminatory I-sites. Increasing the number of discriminatory sites by replacing R5M with I2 inactivated extrachromosomal oriC function. Mutants with no discriminatory sites perturbed host growth and rapidly replaced wild-type chromosomal oriC, but normal function returned if one I-site was restored at either the I2, I3 or R5M position. These observations are consistent with assembly of E. coli pre-RC in vivo from mixtures of DnaA-ATP and DnaA-ADP, with I-site interactions coupling pre-RC assembly to DnaA-ATP levels.

Destabilization of the P site codon-anticodon helix results from movement of tRNA into the P/E hybrid state within the ribosome.

Retention of the reading frame in ribosomal complexes after single-round translocation depends on the acylation state of the tRNA. When tRNA lacking a peptidyl group is translocated to the P site, the mRNA slips to allow re-pairing of the tRNA with a nearby out-of-frame codon. Here, we show that this ribosomal activity results from movement of tRNA into the P/E hybrid state. Slippage of mRNA is suppressed by 3' truncation of the translocated tRNA, increased MgCl2 concentration, and mutation C2394A of the 50S E site, and each of these conditions inhibits P/E-state formation. Mutation G2252U of the 50S P site stimulates mRNA slippage, suggesting that decreased affinity of tRNA for the P/P state also destabilizes mRNA in the complex. The effects of G2252U are suppressed by C2394A, further implicating the P/E state in mRNA destabilization. This work uncovers a functional attribute of the P/E state crucial for understanding translation.

Two discriminatory binding sites in the Escherichia coli replication origin are required for DNA strand opening by initiator DnaA-ATP.

Initiation of DNA replication in eukaryotes, archea, and eubacteria requires interaction of structurally conserved ATP-binding initiator proteins and origin DNA to mediate assembly of replisomes. However, the specific requirement for ATP in the early steps of initiation remains unclear. This is true even for the well studied Escherichia coli replication origin, oriC, where the ATP form of initiator DnaA is necessary and sufficient for initial DNA strand separation, but the five DnaA-binding sites (R boxes) with consensus sequence 5'TGTGNAT/AAA bind both active ATP-DnaA and inactive ADP-DnaA with equal affinity. By using dimethyl sulfate footprinting, we recently identified two initiator-binding sites, I2 and I3, with sequence 5'TG/TGGATCAG/A. We now show that sites I2 and I3 preferentially bind DnaA-ATP and are required for origin unwinding. Guanine at position 3 determines DnaA-ATP preference, and changing this base to thymine at both I sites allows DnaA-ADP to bind and open oriC, although DNA strand separation is not precisely localized in the AT-rich region. These observations indicate that specific initiator binding sites within a replication origin can be important determinants of an ATP-dependent molecular switch regulating DNA strand separation.