On prosthetic control: A regenerative agonist-antagonist myoneural interface

Prosthetic limb control is fundamentally constrained by the current amputation procedure. Since the U.S. Civil War, the external prosthesis has benefited from a pronounced level of innovation, but amputation technique has not significantly changed. During a standard amputation, nerves are transected without the reintroduction of proper neural targets, causing painful neuromas and rendering efferent recordings infeasible. Furthermore, the physiological agonist-antagonist muscle relationships are severed, precluding the generation of musculotendinous proprioception, an afferent feedback modality critical for joint stability, trajectory planning, and fine motor control. We establish an agonist-antagonist myoneural interface (AMI), a unique surgical paradigm for amputation. Regenerated free muscle grafts innervated with transected nerves are linked in agonist-antagonist relationships, emulating the dynamic interactions found within an intact limb. Using biomechanical, electrophysiological, and histological evaluations, we demonstrate a viable architecture for bidirectional signaling with transected motor nerves. Upon neural activation, the agonist muscle contracts, generating electromyographic signal. This contraction in the agonist creates a stretch in the mechanically linked antagonist muscle, producing afferent feedback, which is transmitted through its motor nerve. Histological results demonstrate regeneration and the presence of the spindle fibers responsible for afferent signal generation. These results suggest that the AMI will not only produce robust signals for the efferent control of an external prosthesis but also provide an amputee's central nervous system with critical musculotendinous proprioception, offering the potential for an enhanced prosthetic controllability and sensation.

Risk Factors for Pregnancy Associated Venous Thromboembolism

In an attempt to reduce the incidence of pregnancy associated venous thromboembolism (PA-VTE), some researchers have advocated screening of all women for the factor VLeiden mutation during early pregnancy. We have conducted a large retrospective study (over 72,000 deliveries) to determine if this would be useful. Sixty-two objectively confirmed venous thrombotic events (51 DVT, 11 PE) were recorded at two maternity units in the UK. The incidence of DVT was 0.71 per 1000 deliveries (95% CI 0.5-0.9) with 0.50 occurring in the antenatal period (95% CI 0.34-0.66) and 0.21 in the puerperium (95% CI 0.11-0.31). The incidence of PE was 0.15 per 1000 deliveries (95% CI 0.06-0.24), 0.07 antenatal (95% CI 0.01-0.13) and 0.08 in the puerperium (95% CI 0.02-0.14). Of these 62,50 attended for follow-up and thrombophilia screening. 28% of all episodes of PA-VTE had no CIinical risk factor for thrombosis or an identifiable thrombophilic abnormality. Deficiency of antithrombin was identified in 12% of individuals (95% CI 3-21) and the factor VLeiden mutation in 8% (95% CI 0.5-15.5). Based on estimates of the prevalence of the factor VLeiden mutation in the population, we estimate that the thrombotic risk for a woman during pregnancy or the puerperium with the defect is approximately 1 in 400-500. This figure would not lend support to the idea of random screening for the mutation in early pregnancy.

Superficial Vein Thrombosis: Incidence in Association with Pregnancy and Prevalence of Thrombophilic Defects

Superficial venous thrombotic (SVT) events are a feature of thrombophilic abnormalities, particularly those involving the protein C pathway. We have determined the incidence of SVT associated with pregnancy and the early postpartum period in a retrospective study involving 72 000 deliveries. Fourty-nine cases occurring in 47 individuals were recorded, with an overall incidence of 0.68/1000 deliveries (95% CI 0.48-0.88). None had a previous history of deep vein thrombosis or pulmonary embolism. Most events occurred in the early post-partum period (0.54/1000 deliveries). Twenty-four/fourty-seven were screened for established thrombophilic abnormalities, with only 1 abnormality detected (FVLeiden heterozygote). Thrombophilia may play a minor role in the aetiology of SVT associated with pregnancy, although a larger study is required to confirm this.

Cluster randomized trial to evaluate the impact of team training on surgical outcomes

Background

The application of safety principles from the aviation industry to the operating room has offered hope in reducing surgical complications. This study aimed to assess the impact on major surgical complications of adding an aviation-based team training programme after checklist implementation.

Methods

A prospective parallel-group cluster trial was undertaken between September 2011 and March 2013. Operating room teams from 31 hospitals were assigned randomly to participate in a team training programme focused on major concepts of crew resource management and checklist utilization. The primary outcome measure was the occurrence of any major adverse event, including death, during the hospital stay within the first 30 days after surgery. Using a difference-in-difference approach, the ratio of the odds ratios (ROR) was estimated to compare changes in surgical outcomes between intervention and control hospitals.

Results

Some 22 779 patients were enrolled, including 5934 before and 16 845 after team training implementation. The risk of major adverse events fell from 8·8 to 5·5 per cent in 16 intervention hospitals (adjusted odds ratio 0·57, 95 per cent c.i. 0·48 to 0·68; P < 0·001) and from 7·9 to 5·4 per cent in 15 control hospitals (odds ratio 0·64, 0·50 to 0·81; P < 0·001), resulting in the absence of difference between arms (ROR 0·90, 95 per cent c.i. 0·67 to 1·21; P = 0·474). Outcome trends revealed significant improvements among ten institutions, equally distributed across intervention and control hospitals.

Conclusion

Surgical outcomes improved substantially, with no difference between trial arms. Successful implementation of an aviation-based team training programme appears to require modification and adaptation of its principles in the context of the the surgical milieu. Registration number: NCT01384474 (http://www.clinicaltrials.gov).

Initial experience of dual maintenance immunosuppression with steroid withdrawal in vascular composite tissue allotransplantation

Current immunosuppression in VCA is largely based on the experience in solid organ transplantation. It remains unclear if steroids can be reduced safely in VCA recipients. We report on five VCA recipients who were weaned off maintenance steroids after a median of 2 months (mean: 4.8 months, range 2-12 months). Patients were kept subsequently on a low dose, dual maintenance consisting of tacrolimus and mycophenolate mofetil/mycophenloic acid with a mean follow-up of 43.6 months (median = 40 months, range 34-64 months). Early and late acute rejections responded well to temporarily augmented maintenance, topical immunosuppression, and/or steroid bolus treatment. One late steroid-resistant acute rejection required treatment with thymoglobulin. All patients have been gradually weaned off steroids subsequent to the treatment of acute rejections. Low levels of tacrolimus (<5 ng/mL) appeared as a risk for acute rejections. Although further experience and a cautious approach are warranted, dual-steroid free maintenance immunosuppression appears feasible in a series of five VCA recipients.

Systematic review of methodological quality of individual performance measurement in surgery

Background

Calls for greater transparency with improved quality, safety and outcomes have led to performance tracking of individual surgeons. This study evaluated the methodology of studies investigating individual performance in surgery.

Methods

MEDLINE, Embase, PsycINFO, AMED and the Cochrane Database of Systematic Reviews (from their inception to July 2014) were searched. Two authors independently reviewed citations using predetermined inclusion and exclusion criteria; 91 data points per study were extracted.

Results

The search strategy yielded 8514 citations; 101 were eligible, comprising 1 006 037 procedures by 14 455 surgeons. Thirty-four studies were prospective and 66 were retrospective. The aim of the studies was either to assess individual performance and describe the learning curve of a procedure, to describe factors influencing performance, or to describe methods for routine performance monitoring. Some 51·5 per cent of the studies investigated 500 or fewer procedures. Most (77 of 101) were single-centre studies. Less than half of the studies (42, 41·6 per cent) employed statistical modelling or stratification to adjust performance measures. Forty studies (39·6 per cent) adjusted outcomes for case mix. Seventeen (16·8 per cent) adjusted metrics for surgeon-specific factors. Thirteen studies (12·9 per cent) considered clustering in their analyses. The most frequent outcome studied was duration of operation (59·4 per cent), followed by complication rate (45·5 per cent) and reoperation rate (29·7 per cent); 15·8 per cent of studies recorded mortality, and 4·0 per cent explored patient satisfaction. Only 48·5 per cent of studies displayed procedural learning curves using a graph.

Conclusion

There exist substantial shortcomings in methodological quality, outcome measurements and quality improvement evaluation among current studies of individual surgical performance. Methodological guidelines should be established to ensure that assessments are valid.

Angiographic embolisation in the management of pelvic haemorrhage

Haemorrhage from pelvic veins during obstetric and gynaecological surgery is a major cause of morbidity and mortality. In a recent commentary entitled The Seven Surgeons of King's: a fable by Aesop(1), surgeons from different specialties used techniques peculiar to their own practice to treat a woman with intractable haemorrhage. Could transcatheter arterial embolisation be the 'eighth surgeon'? We describe two cases where embolisation was used to control bleeding when local surgical measures had failed and discuss the use of embolisation in obstetrics and gynaecology.

Superficial vein thrombosis: incidence in association with pregnancy and prevalence of thrombophilic defects

Superficial venous thrombotic (SVT) events are a feature of thrombophilic abnormalities, particularly those involving the protein C pathway. We have determined the incidence of SVT associated with pregnancy and the early postpartum period in a retrospective study involving 72000 deliveries. Fourty-nine cases occurring in 47 individuals were recorded, with an overall incidence of 0.68/1000 deliveries (95% CI 0.48-0.88). None had a previous history of deep vein thrombosis or pulmonary embolism. Most events occurred in the early postpartum period (0.54/1000 deliveries). Twenty-four/fourty-seven were screened for established thrombophilic abnormalities, with only 1 abnormality detected (FV(Leiden) heterozygote). Thrombophilia may play a minor role in the aetiology of SVT associated with pregnancy, although a larger study is required to confirm this.

Risk factors for pregnancy associated venous thromboembolism

In an attempt to reduce the incidence of pregnancy associated venous thromboembolism (PA-VTE), some researchers have advocated screening of all women for the factor V(Leiden) mutation during early pregnancy. We have conducted a large retrospective study (over 72,000 deliveries) to determine if this would be useful. Sixty-two objectively confirmed venous thrombotic events (51 DVT, 11 PE) were recorded at two maternity units in the UK. The incidence of DVT was 0.71 per 1000 deliveries (95% CI 0.5-0.9) with 0.50 occurring in the antenatal period (95% CI 0.34-0.66) and 0.21 in the puerperium (95% CI 0.11-0.31). The incidence of PE was 0.15 per 1000 deliveries (95% CI 0.06-0.24), 0.07 antenatal (95% CI 0.01-0.13) and 0.08 in the puerperium (95% CI 0.02-0.14). Of these 62, 50 attended for follow-up and thrombophilia screening. 28% of all episodes of PA-VTE had no clinical risk factor for thrombosis or an identifiable thrombophilic abnormality. Deficiency of antithrombin was identified in 12% of individuals (95% CI 3-21) and the factor V(Leiden) mutation in 8% (95% CI 0.5-15.5). Based on estimates of the prevalence of the factor V(Leiden) mutation in the population, we estimate that the thrombotic risk for a woman during pregnancy or the puerperium with the defect is approximately 1 in 400-500. This figure would not lend support to the idea of random screening for the mutation in early pregnancy.

Early prenatal investigation of a pregnancy at risk of adenosine deaminase deficiency using chorionic villi

A pregnancy at risk for adenosine deaminase deficiency and severe combined immunodeficiency disease was investigated using samples of chorionic villi obtained during the eighth week of pregnancy. Adenosine deaminase levels suggested that the fetus was a probable carrier and that a diagnosis of severe combined immunodeficiency disease could be excluded. Enzyme and chromosome results were available within 24 hours of the chorionic villous sampling procedure, and were confirmed on amniotic fluid cell cultures after amniocentesis at 17 weeks' gestation and on cord blood at delivery.

Tubo-ovarian actinomycosis and the IUCD

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Coagulation and fibrinolytic properties of peripheral venous blood in chronic ectopic pregnancy

The coagulation and fibrinolytic properties of peripheral venous blood was studied in 10 Black patients with chronic ectopic pregnancy. There were significant elevations of plasma fibrinogen and serum fibrin-fibrinogen degradation products (FDP) and prolongation of the euglobulin lysis time. These features are believed to be compatible with chronic inflammation. No evidence of a haemostatic defect was found.

Ambulance transport of obstetric emergencies

Ninety-eight patient records from obstetric flying squad calls were reviewed. The reasons for call-out and the effect of transport on maternal and foetal cardiovascular parameters were analysed. The main reason for calling the flying squad is now antepartum haemorrhage. Transporting the patient to hospital has little effect on the cardiovascular state.

An ultrastructural study of the reversibility of the effects of hypoxia on human trophoblast maintained in organ culture

Ultrastructural changes in normal human trophoblast maintained in hypoxic organ culture are described. Marked structural changes were noted even after hypoxia for 6 hr. These changes could be partly reversed by reoxygenation after hypoxia for 18 hr or less, but no regeneration occurred when hypoxia lasted for 24 hr or longer. The significance of the vulnerability of trophoblast to hypoxia is discussed.

Maternal bronchial carcinoma and its possible relation to neonatal hypoglycaemia

A neonate whose mother had been diagnosed as suffering from bronchial carcinoma presented with many of the features characterizing the syndrome shown by babies of diabetic mothers. It is suggested that over-production of corticotrophin in the mother was responsible for the hypoglycaemia and other manifestations in the infant.