Organ curvature sensing using pneumatically attachable flexible rails in robotic-assisted laparoscopic surgery.

In robotic-assisted partial nephrectomy, surgeons remove a part of a kidney often due to the presence of a mass. A drop-in ultrasound probe paired to a surgical robot is deployed to execute multiple swipes over the kidney surface to localise the mass and define the margins of resection. This sub-task is challenging and must be performed by a highly-skilled surgeon. Automating this sub-task may reduce cognitive load for the surgeon and improve patient outcomes. The eventual goal of this work is to autonomously move the ultrasound probe on the surface of the kidney taking advantage of the use of the Pneumatically Attachable Flexible (PAF) rail system, a soft robotic device used for organ scanning and repositioning. First, we integrate a shape-sensing optical fibre into the PAF rail system to evaluate the curvature of target organs in robotic-assisted laparoscopic surgery. Then, we investigate the impact of the PAF rail's material stiffness on the curvature sensing accuracy, considering that soft targets are present in the surgical field. We found overall curvature sensing accuracy to be between 1.44% and 7.27% over the range of curvatures present in adult kidneys. Finally, we use shape sensing to plan the trajectory of the da Vinci surgical robot paired with a drop-in ultrasound probe and autonomously generate an Ultrasound scan of a kidney phantom.

A randomised controlled trial comparing deep neuromuscular blockade reversed with sugammadex with moderate neuromuscular block reversed with neostigmine.

Deep neuromuscular block aims to improve operative conditions during laparoscopic surgery with a lower intra-abdominal pressure. Studies are conflicting on whether meaningful improvements in quality of recovery occur beyond emergence, and whether lower intra-abdominal pressure is achieved. In this pragmatic randomised trial with 1:1 allocation, adults undergoing elective laparoscopic surgery were allocated to moderate neuromuscular block reversed with neostigmine, or deep neuromuscular block reversed with sugammadex. Allocation was revealed to the anaesthetist only. Primary outcome was cognitive recovery of the Postoperative Quality of Recovery Scale, 7 days after surgery. Secondary outcomes included recovery in other domains of the Postoperative Quality of Recovery Scale at 15 min and 40 min; days 1, 3, 7, 14; and 1 and 3 months after surgery. Chi-square test was used for the primary outcome, and generalised linear mixed model for recovery over time between groups. Of 350 participants randomised, 140 (deep) and 144 (moderate) were analysed for the primary outcome. There was no difference in the Postoperative Quality of Recovery Scale cognitive domain at day 7 (deep 92.9% vs. moderate 91.8%, OR 1.164; 95%CI 0.486-2.788, p = 0.826), or at any other time-point. No significant difference was observed for physiological, emotive, activities of daily living, nociception, or overall recovery. Length of stay in the recovery area (mean (SD) deep 108 (58) vs. moderate 109 (57) min, p = 0.78) and hospital (1.8 (1.9) vs. 2.6 (3.5) days, p = 0.019) was not different. Intra-abdominal pressure and surgical operating conditions were not different between groups. Deep neuromuscular block did not improve quality of recovery compared with moderate neuromuscular block in operative laparoscopic surgery over a 1-h duration.

Validation of the cognitive recovery assessments with the Postoperative Quality of Recovery Scale in patients with low-baseline cognition.

Patients with pre-surgery cognitive impairment cannot currently be assessed for cognitive recovery after surgery using the Postoperative Quality of Recovery Scale (PostopQRS), as they would mathematically be scored as recovered. We aimed to validate a novel method to score cognitive recovery in patients with low-baseline cognition, using the number of low-score tests rather than their numerical values. Face validity was demonstrated in 86 participants in whom both the Postoperative Quality of Recovery Scale and an 11-item neuropsychological battery were performed. The Postoperative Quality of Recovery Scale agreed with neuropsychological categorisation of low vs. normal cognition 74% of the time, with all but five incorrectly coded participants deviating by only one neurocognitive test. Cognitive recovery over time was comparable for groups with differing baseline cognitive function, irrespective of whether the Postoperative Quality of Recovery Scale or neuropsychological methods were used. Discriminant validation was demonstrated in a post-hoc analysis of the steroids in cardiac surgery substudy by allocating groups to normal (n = 246) or low-baseline cognition (n = 231) stratified by cognitive recovery on day 1. Recovery was similar for participants with low and normal baseline cognition. Postoperative length of stay was longer in patients with failed cognitive recovery whether they had normal mean (SD) (10.4 (10.0) vs. 8.0 (5.9) days, p = 0.02) or low-baseline cognition (12.0 (11.1) vs. 8.2 (4.7) days, p < 0.01). Overall quality, as well as cognitive, emotive and physiological recovery was independent of baseline cognition. The modified scoring method for the Postoperative Quality of Recovery Scale cognitive domain demonstrates acceptable face and discriminant validity.

Role of chromogenic assays in haemophilia A and B diagnosis.

The laboratory diagnosis and monitoring of factors VIII and IX have been primarily by one-stage clotting assay (OSA) for many years. Chromogenic assays (CSA) have been available only in specialist laboratories and not for routine use. Significant differences, of more than 1.5-fold in results between the 2 assay methods, have been described in Europe and Australia in approximately one-third of patients with mild haemophilia A. In certain discrepant groups with restricted F8 gene mutations, the OSA results are more than 1.5-fold higher than CSA and risk a missed or misleading diagnostic result. More recently, an assay discrepancy in haemophilia B has been reported. With the introduction of extended half-life (EHL) FVIII and FIX products, it is likely most coagulation laboratories will need to evaluate at least one CSA and gain experience with this technique. The validation of CSA involves a careful appraisal of calibration curve linearity, limit of detection, precision, reference range, quality control material, sample analysis, method comparison and cost. This review will discuss the current status of FVIII and FIX CSA for the diagnosis of haemophilia A and B and describe approaches to implement CSA into the laboratory repertoire.

Qualification of a select one-stage activated partial thromboplastin time-based clotting assay and two chromogenic assays for the post-administration monitoring of nonacog beta pegol.

Essentials Nonacog beta pegol (N9-GP) is an extended half-life, recombinant human factor IX (FIX). One-stage clotting (OSC) and chromogenic FIX activity assays were assessed for N9-GP recovery. OSC STA® -Cephascreen® , ROX FIX and BIOPHEN FIX chromogenic assays were qualified for N9-GP. Other extended half-life factor products should be assessed in a similar way prior to approval. SUMMARY: Background Nonacog beta pegol (N9-GP) is an extended half-life, glycoPEGylated recombinant human factor IX that is under development for the prophylaxis and treatment of bleeding episodes in hemophilia B patients. Considerable reagent-dependent variability has been observed when one-stage clotting assays are used to measure the recovery of recombinant FIX products, including N9-GP. Objective To qualify select one-stage clotting and chromogenic FIX activity assays for measuring N9-GP recovery. Methods The accuracy and precision of the one-stage clotting assay (with the STA-Cephascreen activated partial thromboplastin [APTT] reagent) and the ROX Factor IX and BIOPHEN Factor IX chromogenic assays for measuring N9-GP recovery were assessed in N9-GP-spiked hemophilia B plasma samples in a systematic manner at three independent sites, with manufacturer-recommended protocols and/or site-specific assay setups, including different instruments. Results For each of the three FIX activity assays qualified on five different reagent-instrument systems, acceptable intra-assay and interassay accuracy and precision, dilution integrity, reagent robustness and freeze-thaw and short-term sample stabilities were demonstrated. The STA-Cephascreen assay showed a limited reportable range at one of the three qualification sites, and the BIOPHEN Factor IX assay showed suspect low-end sensitivity at one of the three qualification sites. An individual laboratory would account for these limitations by adjusting the assay's reportable range; thus, these findings are not considered to impact the respective assay qualifications. Conclusion The one-stage clotting assay with the STA-Cephascreen APTT reagent, the ROX Factor IX chromogenic assay and the BIOPHEN Factor IX chromogenic assay are considered to be qualified for the measurement of N9-GP in 3.2% (0.109 m) citrated human plasma.

Measuring FVIII activity of glycopegylated recombinant factor VIII, N8-GP, with commercially available one-stage clotting and chromogenic assay kits: a two-centre study.

INTRODUCTION: Factor VIII activity (FVIII:C) assays of samples containing glycoPEGylated recombinant FVIII such as turoctocog alfa pegol (N8-GP) can be associated with differences in FVIII recovery in vitro between various one-stage activated partial thromboplastin time (APTT)-based clotting assays and some chromogenic assays. Careful validation and qualification of specific assays and conditions is therefore necessary for the assessment of FVIII:C in samples containing modified FVIII molecules. AIM: To assess the ability of various one-stage clotting and chromogenic FVIII:C assays to measure samples containing N8-GP compared to unmodified recombinant FVIII (rFVIII) across two laboratory sites. METHODS: Factor VIII activity in severe haemophilia A (HA) plasma spiked with a range of concentrations (from low, 0.20 IU mL-1 , to high, 0.90 IU mL-1 ) of N8-GP and rFVIII, was determined at two laboratory sites using 12 commercially available one-stage clotting and chromogenic FVIII:C assays. Assays were performed using a plasma calibrator and different analysers. RESULTS: Acceptable N8-GP recovery was observed in the low to high concentration samples tested using the majority of the tested APTT reagents with only one reagent causing a significant underestimation as compared to rFVIII. For the chromogenic assays, a slight overestimation was observed with some of the kits. Variability between the two laboratory sites are likely attributable to the use of different analysers with the respective APTT reagents. CONCLUSIONS: These results highlight the need to investigate the performance of modified factor products using standard assays. The performance of different one-stage clotting assays, APTT reagents, reference calibrators and instrumentation should also be evaluated.

Precision-feeding dairy heifers a high rumen-undegradable protein diet with different proportions of dietary fiber and forage-to-concentrate ratios.

The addition of dietary fiber can alter nutrient and N utilization in precision-fed dairy heifers and may further benefit from higher inclusion levels of RUP. The objective of this experiment was to determine the effects of feeding a high-RUP diet when dietary fiber content was manipulated within differing forage-to-concentrate ratios (F:C) on nutrient utilization of precision-fed dairy heifers. Six rumen-cannulated Holstein heifers (555.4 ± 31.4 kg BW; 17.4 ± 0.1 mo) were randomly assigned to 2 levels of forage, high forage (HF; 60% forage) or low forage (LF; 45% forage), and to a fiber proportion sequence (low fiber: 100% oat hay and silage [OA], 0% wheat straw [WS]; medium fiber: 83.4% OA, 16.6% WS; and high fiber: 66.7% OA, 33.3% WS) administered according to a split-plot 3 × 3 Latin square design (21-d periods). Similar levels of N intake (1.70 g N/kg BW) and RUP (55% of CP) were provided. Data were analyzed as a split-plot, 3 × 3 Latin square design using a mixed model with fixed effects of period and treatment. A repeated measures model was used with data that had multiple measurements over time. No differences were observed for DM, OM, NDF, or ADF apparent digestibility coefficients (dC) between HF- and LF-fed heifers. Heifers receiving LF diets had greater starch dC compared to HF heifers. Increasing the fiber level through WS addition resulted in a linear reduction of OM dC. There was a linear interaction for DM dC with a concurrent linear interaction in NDF dC. Nitrogen intake, dC, and retention did not differ; however, urine and total N excretion increased linearly with added fiber. Predicted microbial CP flow (MP) linearly decreased with WS inclusion mainly in LF heifers, as indicated by a significant interaction between F:C and WS. Rumen pH linearly increased with WS addition, although no F:C effect was detected. Ruminal ammonia concentration had an opposite linear effect with respect to MP as WS increased. Diets with the higher proportion of fiber benefited the most from a high RUP supply, complementing the substantial reduction in predicted MP caused by the incremental dietary fiber concentration. These results suggest that RUP supplementation is a practical method for reestablishing optimal ruminal N balance in the event of increased dietary fiber through forage inclusion in precision-fed dairy heifer diets.

Measuring factor IX activity of nonacog beta pegol with commercially available one-stage clotting and chromogenic assay kits: a two-center study.

UNLABELLED: Essentials Validated assays are required to precisely measure factor IX (FIX) activity in FIX products. N9-GP and two other FIX products were assessed in various coagulation assay systems at two sites. Large variations in FIX activity measurements were observed for N9-GP using some assays. One-stage and chromogenic assays accurately measuring FIX activity for N9-GP were identified. SUMMARY: Background Measurement of factor IX activity (FIX:C) with activated partial thromboplastin time-based one-stage clotting assays is associated with a large degree of interlaboratory variation in samples containing glycoPEGylated recombinant FIX (rFIX), i.e. nonacog beta pegol (N9-GP). Validation and qualification of specific assays and conditions are necessary for the accurate assessment of FIX:C in samples containing N9-GP. Objectives To assess the accuracy of various one-stage clotting and chromogenic assays for measuring FIX:C in samples containing N9-GP as compared with samples containing rFIX or plasma-derived FIX (pdFIX) across two laboratory sites. Methods FIX:C, in severe hemophilia B plasma spiked with a range of concentrations (from very low, i.e. 0.03 IU mL(-1) , to high, i.e. 0.90 IU mL(-1) ) of N9-GP, rFIX (BeneFIX), and pdFIX (Mononine), was determined at two laboratory sites with 10 commercially available one-stage clotting assays and two chromogenic FIX:C assays. Assays were performed with a plasma calibrator and different analyzers. Results A high degree of variation in FIX:C measurement was observed for one-stage clotting assays for N9-GP as compared with rFIX or pdFIX. Acceptable N9-GP recovery was observed in the low-concentration to high-concentration samples tested with one-stage clotting assays using SynthAFax or DG Synth, or with chromogenic FIX:C assays. Similar patterns of FIX:C measurement were observed at both laboratory sites, with minor differences probably being attributable to the use of different analyzers. Conclusions These results suggest that, of the reagents tested, FIX:C in N9-GP-containing plasma samples can be most accurately measured with one-stage clotting assays using SynthAFax or DG Synth, or with chromogenic FIX:C assays.

Postoperative recovery and outcomes--what are we measuring and for whom?

Recovery is an abstract quantity the definition of which varies according to the pre-dilection of individual institutions, clinicians or patients. While traditionally focused on immediate postoperative restitution of function and readiness for discharge, recovery assessment has progressively expanded its focus to include other clinically relevant time periods, each of which is influenced by specific factors. Assessment tools have progressed from assessing one dimension of recovery, such as physiological variables, to multidimensional assessment of physical, nociceptive, emotive, functional and cognitive performance. They should be validated ideally for repeat measures and should provide real-time recovery data, as recovery can be viewed as a continuous process.

X-ray, spectroscopic and normal-mode dynamics of calexcitin: structure-function studies of a neuronal calcium-signalling protein.

The protein calexcitin was originally identified in molluscan photoreceptor neurons as a 20 kDa molecule which was up-regulated and phosphorylated following a Pavlovian conditioning protocol. Subsequent studies showed that calexcitin regulates the voltage-dependent potassium channel and the calcium-dependent potassium channel as well as causing the release of calcium ions from the endoplasmic reticulum (ER) by binding to the ryanodine receptor. A crystal structure of calexcitin from the squid Loligo pealei showed that the fold is similar to that of another signalling protein, calmodulin, the N- and C-terminal domains of which are known to separate upon calcium binding, allowing interactions with the target protein. Phosphorylation of calexcitin causes it to translocate to the cell membrane, where its effects on membrane excitability are exerted and, accordingly, L. pealei calexcitin contains two protein kinase C phosphorylation sites (Thr61 and Thr188). Thr-to-Asp mutations which mimic phosphorylation of the protein were introduced and crystal structures of the corresponding single and double mutants were determined, which suggest that the C-terminal phosphorylation site (Thr188) exerts the greatest effects on the protein structure. Extensive NMR studies were also conducted, which demonstrate that the wild-type protein predominantly adopts a more open conformation in solution than the crystallographic studies have indicated and, accordingly, normal-mode dynamic simulations suggest that it has considerably greater capacity for flexible motion than the X-ray studies had suggested. Like calmodulin, calexcitin consists of four EF-hand motifs, although only the first three EF-hands of calexcitin are involved in binding calcium ions; the C-terminal EF-hand lacks the appropriate amino acids. Hence, calexcitin possesses two functional EF-hands in close proximity in its N-terminal domain and one functional calcium site in its C-terminal domain. There is evidence that the protein has two markedly different affinities for calcium ions, the weaker of which is most likely to be associated with binding of calcium ions to the protein during neuronal excitation. In the current study, site-directed mutagenesis has been used to abolish each of the three calcium-binding sites of calexcitin, and these experiments suggest that it is the single calcium-binding site in the C-terminal domain of the protein which is likely to have a sensory role in the neuron.

A review of the scope and measurement of postoperative quality of recovery.

To date, postoperative quality of recovery lacks a universally accepted definition and assessment technique. Current quality of recovery assessment tools vary in their development, breadth of assessment, validation, use of continuous vs dichotomous outcomes and focus on individual vs group recovery. They have progressed from identifying pure restitution of physiological parameters to multidimensional assessments of postoperative function and patient-focused outcomes. This review focuses on the progression of these tools towards an as yet unreached ideal that would provide multidimensional assessment of recovery over time at the individual and group level. A literature search identified 11 unique recovery assessment tools. The Postoperative Quality of Recovery Scale assesses recovery in multiple domains, including physiological, nociceptive, emotive, activities of daily living, cognition and patient satisfaction. It addresses recovery over time and compares individual patient data with base line, thus describing resumption of capacities and is an acceptable method for identification of individual patient recovery.

Crystallization and preliminary X-ray characterization of the 2,4'-dihydroxyacetophenone dioxygenase from Alcaligenes sp. 4HAP.

The enzyme 2,4'-dihydroxyacetophenone dioxygenase (or DAD) catalyses the conversion of 2,4'-dihydroxyacetophenone to 4-hydroxybenzoic acid and formic acid with the incorporation of molecular oxygen. Whilst the vast majority of dioxygenases cleave within the aromatic ring of the substrate, DAD is very unusual in that it is involved in C-C bond cleavage in a substituent of the aromatic ring. There is evidence that the enzyme is a homotetramer of 20.3 kDa subunits each containing nonhaem iron and its sequence suggests that it belongs to the cupin family of dioxygenases. By the use of limited chymotrypsinolysis, the DAD enzyme from Alcaligenes sp. 4HAP has been crystallized in a form that diffracts synchrotron radiation to a resolution of 2.2 Å.

The impact on cardiac diagnosis and mortality of focused transthoracic echocardiography in hip fracture surgery patients with increased risk of cardiac disease: a retrospective cohort study.

Hip fracture surgery is associated with a high rate of mortality and morbidity; heart disease is the leading cause and is often unrecognised and inadequately treated. Pre-operative focused transthoracic echocardiography by anaesthetists frequently influences management, but mortality outcome studies have not been performed to date. Mortality over the 12 months after hip fracture surgery, in 64 patients at risk of cardiac disease who received pre-operative echocardiography, was compared with 66 randomised historical controls who did not receive echocardiography. Mortality was lower in the group that received echocardiography over the 30 days (4.7% vs 15.2%, log rank p=0.047) and 12 months after surgery (17.1% vs 33.3%, log rank p=0.031). Hazard of death was also reduced with pre-operative echocardiography over 12 months after adjustment for known risk factors (hazard ratio 0.41, 95% CI 0.2-0.85, p=0.016). Pre-operative echocardiography was not associated with a delay in surgery. These data support a randomised controlled trial to confirm these findings.

The investigation of a prolonged APTT with specific clotting factor assays is unnecessary if an APTT with Actin FS is normal.

INTRODUCTION: An isolated prolongation to the activated partial thromboplastin time (APTT) can be caused by the presence of the lupus anticoagulant or an intrinsic or contact factor deficiency, of which only deficiencies of factors VIII, IX or XI are associated with bleeding. Our local protocol states that further investigation of a prolonged APTT by specific assays of FVIII, FIX and FXI should only be undertaken where the APTT with one reagent (Synthasil) is more than 3 s prolonged, and further investigation by an APTT with a second reagent (Actin FS) is also prolonged, unless there is a history of bleeding in the patient, in which case assays are indicated irrespective of the APTT. METHODS: We retrospectively reviewed the results of all APTTs performed over a 36-month period to evaluate whether strictly applying our protocol would reduce the number of unnecessary clotting factor assays performed, without leaving patients with potentially significant bleeding disorders undiagnosed. RESULTS: Of a total number of 587 samples tested for coagulation factors VIII, IX and XI, only 117 samples yielded an abnormal result. Thus, 80% of all the assays requested in the 3-year period audited gave a result within the reference range for factors VIII, FIX and XI. Three quarters of the abnormal results revealed mild FXI deficiency. CONCLUSION: This review has demonstrated that no significant coagulation factor deficiency would be left undiagnosed if the protocol was followed. This would have considerably reduced the cost and time spent performing these assays.

The responsiveness of different APTT reagents to mild factor VIII, IX and XI deficiencies.

INTRODUCTION: The sensitivity of APTT reagents to deficiencies of factors VIII, IX, XI and XII varies because of their composition. The APTT is used as a screening test for these factors, and a deficiency should manifest with a prolongation to the APTT, which may trigger the need for specific factor assays to be performed. METHODS: The suitability of APTT reagents to detect mild deficiencies can be assessed by the analysis of the APTT of plasma, which has an increasing concentration of the factor in question. The APTT responsiveness can be determined from the intersection of the curve and the upper limit of the APTT normal reference range for that APTT reagent. We assessed the APTT responsiveness (in U/dl) to factors VIII, IX and XI of four APTT reagents; Actin FS (Siemens), Synthasil (IL), STA-PTTA (Stago) and Dapttin (Technoclone). RESULTS: Actin FS was the most sensitive reagent to mild reductions of factors VIII, IX and XI [Correction added on 26 October 2010, after first online publication: Synthasil was corrected to Actin FS]. STA-PTTA showed less sensitivity than Synthasil and Actin FS; Dapttin was insensitive to mild deficiencies of factors IX and XI and should not be used as a screening test. CONCLUSION: Both Synthasil and Actin FS are acceptable reagents to screen for reduced factors VIII, IX and XI, and the number of mildly reduced factors not diagnosed will be limited.

Structure and function of the l-threonine dehydrogenase (TkTDH) from the hyperthermophilic archaeon Thermococcus kodakaraensis.

The X-ray structure of the holo-form of l-threonine dehydrogenase (TDH) from Thermococcus kodakaraensis (TkTDH) has been determined at 2.4A resolution. TDH catalyses the NAD(+)-dependent oxidation of l-threonine to 2-amino-3-ketobutyrate, and is one of the first enzymes in this family to be solved by X-ray crystallography. The enzyme is a homo-tetramer, each monomer consisting of 350 amino acids that form two domains; a catalytic domain and a nicotinamide co-factor (NAD(+))-binding domain, which contains an alpha/beta Rossmann fold motif. An extended twelve-stranded beta-sheet is formed by the association of pairs of monomers in the tetramer. TkTDH shows strong overall structural similarity to TDHs from thermophiles and alcohol dehydrogenases (ADH) from lower life forms, despite low sequence homology, exhibiting the same overall fold of the monomer and assembly of the tetramer. The structure reveals the binding site of the essential co-factor NAD(+) which is present in all subunits. Docking studies suggest a mode of interaction of TDH with 2-amino-3-ketobutyrate CoA ligase, the subsequent enzyme in the pathway for conversion of threonine to glycine. TDH is known to form a stable functional complex with 2-amino-3-ketobutyrate ligase, most probably to shield an unstable intermediate.