Clinical Acceptability of Artificial Intelligence-Screened Interstitial Lung Disease (AI-ILD) in Lung Cancer Patients Treated with Radiotherapy

PURPOSE/OBJECTIVE(S)

Patients with interstitial lung disease (ILD) treated with thoracic radiotherapy (RT) are at greater risk of pulmonary toxicity. Automatic universal screening for ILD allows radiation oncologists (ROs) to risk stratify patients and implement necessary modifications to their respiratory monitoring or treatment. Automatic screening however may affect RO workload and so it is imperative to assess the clinical acceptability of this tool.

MATERIALS/METHODS

We have developed a machine learning algorithm to identify patients who are at high risk of having ILD based on RT planning computed tomography (CT) images. A quality improvement (QI) project was initiated to test feasibility and acceptability of the machine learning algorithm. If positive, the results of the machine learning algorithm were made available to ROs via structured electronic reporting. ROs were prompted to review the patient and consider expert radiologist consultation if thought appropriate. All electronic surveys and qualitative comments were summarized to describe clinical acceptability. Expert radiologist established gold standard ILD status of all patients on the study. A formal review of RO feedback was collected for all screen-positive, true-positive cases.

RESULTS

Two hundred forty cases were screened of which 45 were flagged as AI-ILD positive and the responsible RO notified. Of these 45 screen-positive cases, all continued on to RT except for 3 patients with tumor progression. From these 45, 24 surveys were completed, 21 had no prior suspicion of ILD. There were 7 true-positives, of which 1 had a survey response. Based on the survey responses, 88% of cases underwent review by the responsible RO. In 16 cases this automatic notification prompted case consultation with an expert radiologist. Expert review was performed from 10 minutes up to 53 hours after the email prompt to the radiologist, with median response time of 1.5 hours. In the 7 screen-positive, true-positive cases, only 2 were not previously known to the responsible RO. In the two cases where true-positive ILD status was previously unknown, one was a mild case of ILD and the other had previously received thoracic RT at this institution without ILD being identified, in both cases the ROs were grateful that this diagnosis was identified prior to treatment. RO confidence in the machine learning prediction was moderate due to the high proportion of false positives.

CONCLUSION

Based on available survey results, more than 75% of the screen-positive cases were reviewed by the responsible RO and two-thirds of these involved expert radiology input. RO feedback was generally positive and this tool was rated as a net benefit despite the high rate of false-positives and the need for clarification.

Association of Artificial Intelligence-Screened Interstitial Lung Disease with Radiation Pneumonitis and Mortality in Locally Advanced Non-Small Cell Lung Cancer

PURPOSE/OBJECTIVE(S)

Radiation pneumonitis (RP) is a common and dose-limiting toxicity following radiotherapy for non-small cell lung cancer (NSCLC). Patients with interstitial lung disease (ILD) are believed to be at increased risk of developing complications including RP, ILD progression, or death. An automated method to identify patients prior to radiotherapy at high risk of developing toxicities or death may allow clinicians to mitigate risk through informed treatment planning and careful patient monitoring.

MATERIALS/METHODS

All locally advanced NSCLC patients treated with definitive radiation from 2006-2021 with a minimum 1 year of follow-up were assessed. RP and mortality data were prospectively collected and retrospectively reviewed. A convolutional neural network (CNN) was previously developed and validated to identify patients with radiographic ILD using planning computed tomography (CT) images, with an accuracy of 0.82. Planning CT scans for the retrospective cohort were used as input to the CNN, with artificial intelligence-screened ILD (AI-ILD) score as an output. AI-ILD scores above our established threshold were labeled as AI-ILD+. The association between AI-ILD score, AI-ILD+/-, mean lung dose (MLD), and the primary outcome of grade ≥2 (G2+) RP or mortality, as well as the secondary outcomes of G2+ RP and mortality were assessed using Wilcoxon rank sum test, univariate and multivariable logistic regression, and Kaplan-Meier survival analysis.

RESULTS

Of 799 patients reviewed, 745 eligible patients were included in the analysis; grade 0-5 RP was reported in 51.3%, 27.1%, 16.9%, 4.0%, 0.1%, and 0.5% of patients respectively. Overall, 22.9% of patients were AI-ILD+, and therefore at high risk (>20% chance) of having true ILD. On UVA, AI-ILD score, AI-ILD+ and MLD were significantly associated with the primary outcome of G2+ RP or mortality, as well as the secondary outcome of mortality. However, only MLD was significantly associated with the secondary outcome of G2+ RP. On MVA, both AI-ILD+ (OR 1.42, 95% CI 1.02-1.97, p = 0.04) and MLD (OR 1.13, 95% 1.05-1.21, p = 0.008) were significantly associated with G2+ RP or mortality. On Kaplan-Meier analysis, the median toxicity-free survival (TFS) time for AI-ILD+ and AI-ILD- patients were 1.7 and 3.4 years respectively, with a 2-year TFS of 48.3% vs. 59.3% (log-rank test: p = 0.02). There was no significant difference in rates of G2+ RP.

CONCLUSION

The AI-ILD algorithm can detect high risk patients with significantly decreased TFS following definitive treatment for NSCLC. AI-ILD classification was not associated with a significant difference in rates of RP when accounting for MLD. Future work will focus on improving the classification algorithm, expert radiologist validation of this dataset, and exploring reasons for the mortality difference in AI-ILD+ patients.

Sex-dependent effects of social status on the regulation of arginine-vasopressin (AVP) V1a, oxytocin (OT), and serotonin (5-HT) 1A receptor binding and aggression in Syrian hamsters (Mesocricetus auratus)

Dominance status in hamsters is driven by interactions between arginine-vasopressin V1a, oxytocin (OT), and serotonin 1A (5-HT1A) receptors. Activation of V1a and OT receptors in the anterior hypothalamus (AH) increases aggression in males, while decreasing aggression in females. In contrast, activation of 5-HT1A receptors in the AH decreases aggression in males and increases aggression in females. The mechanism underlying these differences is not known. The purpose of this study was to determine if dominance status and sex interact to regulate V1a, OT, and 5-HT1A receptor binding. Same-sex hamsters (N = 47) were paired 12 times across six days in five min sessions. Brains from paired and unpaired (non-social control) hamsters were collected immediately after the last interaction and processed for receptor binding using autoradiography. Differences in V1a, OT, and 5-HT1A receptor binding densities were observed in several brain regions as a function of social status and sex. For example, in the AH, there was an interaction between sex and social status, such that V1a binding in subordinate males was lower than in subordinate females and V1a receptor density in dominant males was higher than in dominant females. There was also an interaction in 5-HT1A receptor binding, such that social pairing increased 5-HT1A binding in the AH of males but decreased 5-HT1A binding in females compared with unpaired controls. These results indicate that dominance status and sex play important roles in shaping the binding profiles of key receptor subtypes across the neural circuitry that regulates social behavior.

Recurrent massive pulmonary emboli in a critically ill patient with COVID-19

We report the haematological management of a critically ill patient with coronavirus disease 2019 (COVID-19), with recurrent massive pulmonary emboli. A previous healthy 56-year-old man presented to the emergency department with severe hypoxaemic respiratory failure due to suspected COVID-19. He required invasive mechanical ventilation and transfer to the intensive care unit for increasing ventilatory requirements and cardiovascular instability. A computed tomography (CT) pulmonary angiogram demonstrated large bilateral pulmonary emboli with right heart strain, for which he received intravenous systemic thrombolysis followed by therapeutic weight-adjusted anticoagulation with low molecular weight heparin (dalteparin). Two weeks later, following an acute respiratory deterioration, a repeat CT pulmonary angiogram demonstrated a new saddle embolus with right heart strain requiring another regime of intravenous systemic thrombolysis. This occurred despite anti-Xa-guided therapeutic anticoagulation. The dose of therapeutic dalteparin was increased incrementally to an eventual dose of 12,500 units twice daily. A low threshold for radiological imaging should be considered in all COVID-19 patients with acute cardiorespiratory deterioration. Multidisciplinary team discussions highlighted aspects of balancing the risks of bleeding from anticoagulation vs. risk of death from pulmonary embolism. This report highlights the need for further research into the underlying mechanisms and optimal management of thrombotic complications in COVID-19.

The association between range usage and tibial quality in commercial free-range laying hens

1. Bone tissue adapts continuously to metabolic calcium demands, as well as to external forces due to physical weight loading subject to hen movement. Limited calcium metabolism and, subsequently, its availability from the medullary bone, is a major factor contributing to reduced eggshell quality in hens in the late laying period (>60 weeks of age). 2. Increasing physical activity and biomechanical loading during hen rearing has been demonstrated to increase skeletal strength, enhancing bone mass as well as endocortical and periosteal bone metabolism. Presently, the consequences of range use during lay on bone quality characteristics in laying hens remain unknown. 3.The aims of this study were to characterise tibiotarsal bone indices and evaluate the impact of range access during lay on tibia bone quality in commercial free-range laying hens. 4. This exploratory study described and analysed the volumetric measurements, morphological mechanical and trabeculae indices of the tibiotarsal bone of 48 Lohmann Brown laying hens at 74 weeks of age. All bone parameters were obtained using micro-computed tomography and correlated with individual hen range use. 5. Range usage throughout lay was not associated with tibial trabecular architecture (bone volume and fraction, trabecular thickness, trabecular connectivity density and structural model index), or any other morphological characteristics (breaking strength, diaphyseal diameter, bone weight and bone mineral density) of the tibia (P > 0.05) when hens were 74 weeks of age. 6. The results demonstrated a large variation in individual bone characteristics and suggested that range usage was not associated with bone quality in commercial free-range laying hens used in this study. In conclusion, the bone health of free-range commercial laying hens may be positively impacted by other features, such as hen genetics, feed, the quality of pullet rearing, perch availability or other shed equipment, and the benefits of these variables exceed the benefit of range use.

Flock use of the range is associated with the use of different components of a multi-tier aviary system in commercial free-range laying hens

1. The objective of this study was to investigate the association of using a multi-tier aviary system and access to range on flock uniformity in free-range laying hens, and to determine whether the extent of range use or flock uniformity can be predicted from the use of different levels of the aviary system.2. A total of 13,716 Lohmann Brown hens from five commercial free-range flocks housed in identical houses on the same farm were individually weighed at 16 weeks of age and allocated to five replicate areas within each house. Hen movement in the multi-tier aviary system and on the range was individually monitored using radio frequency identification (RFID). All hens had access to the range from 18 to 22 weeks of age and were exposed to the same management conditions.3. Whilst only one flock significantly changed its flock uniformity with time, they differed from each other in uniformity and body weight (P = 0.001).4. Hens spent most of their available time on the lower aviary tier (7.29 ± 0.029 h/hen/day) and on the upper aviary tier (4.29 ± 0.024 h/hen/day) while the least amount of time was spent on the range and in the nest boxes (0.93 ± 0.005 h/hen/day and 1.48 ± 0.007 h, respectively, P = 0.001).5. Range use was negatively correlated (r = -0.30) to the time spent on the upper aviary tier and positively correlated (r = 0.46) to the time spent on the lower aviary tier (P = 0.001). Bivariate analysis revealed that range and upper aviary resp. lower aviary tier usage had a significant curvilinear association.6. In conclusion, the study showed that range use was associated to the time hens spent on the different tiers of the aviary system. Flock uniformity varied between flocks but was not associated with either range and aviary system usage.

Free-range laying hens: using technology to show the dynamics and impact of hen movement

Free-range laying hens are provided with the opportunity to access various structural areas, including open floor space, feed areas, water lines, next boxes, perches, aviary tiers, winter gardens and ranges. Different individual location preferences can lead to the development of hen subpopulations that are characterised by various health, welfare and performance parameters. Understanding the complexity of hen movement and hen interactions within their environment provides an opportunity to limit the disadvantages that are associated with housing in loose husbandry systems and aids in decision-making. Monitoring hen movement using modern technologies such as radio-frequency identification (RFID), optical flow patterns, image analysis and three-dimensional (3D) cameras allows the accumulation of big data for data mining, clustering and machine learning. Integrating individual-based management systems into modern flock management will not only help improve the care of under-performing hens, but also ensure that elite hens are able to use their full genetic potential, allowing an ethical, sustainable and welfare friendly egg production. This review highlights the dynamics and impact of hen movement in free-range systems, reviews existing knowledge relevant for feeding hens in non-cage systems, and outlines recent technological advances and strategies to improve the management of free-range laying hens.

4 Use of topical haemostatic dressings in an extended field care model of external haemorrhage

Introduction

The use of Celox gauze has been established in military practice as an adjunct in the treatment of external haemorrhage. The future character of conflict means that casualties may take longer to reach definitive care. The aim of this study was to test whether Celox Rapid, a topical haemostatic dressing, would maintain haemostasis during extended use in a junctional haemorrhage model.

Methods

An anaesthetised swine underwent simultaneous bilateral femoral arteriotomies; after 30 s of free bleeding Celox Rapid gauze was applied to the wound and pressure was maintained for 1 min. Following inspection for re-bleeding the Celox gauze was covered with standard field dressings and checked for re-bleeding every hour until the 6 hours had elapsed or the animal deceased.

Results

There was no evidence of re-bleeding at any point up to and including 6 hours. The animal was declared deceased shortly afterwards. Celox Rapid gauze maintained haemostasis in extended use in this limited single animal model. Post mortem examination revealed a stable clot at the site of the arteriotomy with no evidence of re-bleeding.

Conclusion

Celox Rapid was effective at achieving initial homeostasis and preventing re-bleeding in this limited study using a single anaesthetised swine. Its potential for use in situations where evacuation and definitive care may be delayed should be explored.

Identification of new quorum sensing autoinducer binding partners in Pseudomonas aeruginosa using photoaffinity probes

Many bacterial species, including the human pathogen Pseudomonas aeruginosa, employ a mechanism of intercellular communication known as quorum sensing (QS), which is mediated by signalling molecules termed autoinducers. The Pseudomonas Quinolone Signal (PQS) and 2-Heptyl-3H-4-Quinolone (HHQ) are autoinducers in P. aeruginosa, and they are considered important factors in the progress of infections by this clinically relevant organism. Herein, we report the development of HHQ and PQS photoaffinity-based probes for chemical proteomic studies. Application of these probes led to the identification of previously unsuspected putative HHQ and PQS binders, thereby providing new insights into QS at a proteomic level and revealing potential new small molecule targets for virulence attenuation strategies. Notably, we found evidence that PQS binds RhlR, the cognate receptor in the Rhl QS sub-system of P. aeruginosa. This is the first indication of interaction between the Rhl and PQS systems at the protein/ligand level, which suggests that RhlR should be considered a highly attractive target for antivirulence strategies.

Impact of Azithromycin on the Quorum Sensing-Controlled Proteome of Pseudomonas aeruginosa

The macrolide antibiotic, azithromycin (AZM), has been reported to improve the clinical outcome of cystic fibrosis patients, many of whom are chronically-infected with Pseudomonas aeruginosa. However, the highest clinically-achievable concentrations of this drug are well-below the minimum inhibitory concentration for P. aeruginosa, raising the question of why AZM exhibits therapeutic activity. One possibility that has been raised by earlier studies is that AZM inhibits quorum sensing (QS) by P. aeruginosa. To explicitly test this hypothesis the changes brought about by AZM treatment need to be compared with those associated with specific QS mutants grown alongside in the same growth medium, but this has not been done. In this work, we used quantitative 2D-difference gel electrophoresis and 1H-NMR spectroscopy footprint analysis to examine whether a range of clinically-relevant AZM concentrations elicited proteomic and metabolomic changes in wild-type cultures that were similar to those seen in cultures of defined QS mutants. Consistent with earlier reports, over half of the AZM-induced spot changes on the 2D gels were found to affect QS-regulated proteins. However, AZM modulated very few protein spots overall (compared with QS) and collectively, these modulated proteins comprised only a small fraction (12-13%) of the global QS regulon. We conclude that AZM perturbs a sub-regulon of the QS system but does not block QS per se. Reinforcing this notion, we further show that AZM is capable of attenuating virulence factor production in another Gram-negative species that secretes copious quantities of exoenzymes (Serratia marcescens), even in the absence of a functional QS system.

A new Pseudomonas quinolone signal (PQS) binding partner: MexG

Pseudomonas Quinolone Signal (PQS) probes capture a new binding partner for this signal molecule.

The opportunistic pathogen Pseudomonas aeruginosa utilises the cell–cell signalling mechanism known as quorum sensing to regulate virulence. P. aeruginosa produces two quinolone-based quorum sensing signalling molecules; the Pseudomonas quinolone signal (PQS) and its biosynthetic precursor 2-heptyl-4(1H)-quinolone (HHQ). To date, only one receptor (the PqsR protein) has been identified that is capable of binding PQS and HHQ. Here, we report on the synthesis of PQS and HHQ affinity probes for chemical proteomic studies. The PQS affinity probe very effectively captured PqsR in vitro. In addition, we also identified an interaction between PQS and the “orphan” RND efflux pump protein, MexG. The PQS–MexG interaction was further confirmed by purifying MexG and characterizing its ability to bind PQS and HHQ in vitro. Our findings suggest that PQS may have multiple binding partners in the cell and provide important new tools for studying quinolone signalling in P. aeruginosa and other organisms.

Orlistat-induced fulminant hepatic failure

Orlistat was approved by the Food and Drug Administration in 1998 and has been shown to be superior to placebo in achieving weight loss. It is generally well tolerated. However, severe liver injury has been reported. We present a case of hepatic failure in a patient taking orlistat. A 54-year-old African-American woman with hypertension presented with hepatic failure. She had noticed increasing fatigue, jaundice and confusion. She used alcohol sparingly and denied tobacco or illicit drug use, but had been taking over-the-counter orlistat for the past two months. Physical examination revealed scleral icterus, jaundice, asterixis and slow speech. Laboratory testing showed markedly abnormal liver function tests with coagulopathy. Acute viral and autoimmune serologies were negative, as was toxicology screen. Liver biopsy showed necrotic hepatic parenchyma likely secondary to drug toxicity. Based upon her clinical presentation and time course, the pattern of liver injury seen on liver biopsy and lack of an alternative plausible explanation, her liver failure was most likely associated with orlistat use. She continued to deteriorate and ultimately underwent orthotopic liver transplantation. Fourteen cases of severe liver injury associated with orlistat use have been reported, four of which are detailed in the literature. This is the second published case of liver failure associated with over-the-counter orlistat usage. Clinicians should be aware of the growing number of cases associating liver injury and orlistat use and carefully monitor their patients on this medication for signs of hepatic dysfunction.

A Study of the Optical Band Gap of Lithium Tungsten Trioxide Thin Films

The insertion of lithium (lithiation) into tungsten trioxide results in the formation of the tungsten bronze LixWO3. Polycrystalline, rf sputter deposited thin films of LixWO3 were investigated for their application in Smart Window Devices. The optical band gap studies of these films revealed the narrowing of the intrinsic band gap as a consequence of lithium insertion. The results suggest that the rigid band model, which is generally adopted in interpreting the electronic structure of the tungsten bronzes may not be applicable in Lix WO3.

Biofilms and type III secretion are not mutually exclusive in Pseudomonas aeruginosa

Pseudomonas aeruginosa is a Gram-negative opportunistic pathogen that causes acute and chronic infections in immunocompromised individuals. It is also a model organism for bacterial biofilm formation. Acute infections are often associated with planktonic or free-floating cells, high virulence and fast growth. Conversely, chronic infections are often associated with the biofilm mode of growth, low virulence and slow growth that resembles that of planktonic cells in stationary phase. Biofilm formation and type III secretion have been shown to be reciprocally regulated, and it has been suggested that factors related to acute infection may be incompatible with biofilm formation. In a previous proteomic study of the interrelationships between planktonic cells, colonies and continuously grown biofilms, we showed that biofilms under the growth conditions applied are more similar to planktonic cells in exponential phase than to those in stationary phase. In the current study, we investigated how these conditions influence the production of virulence factors using a transcriptomic approach. Our results show that biofilms express the type III secretion system, whereas planktonic cells do not. This was confirmed by the detection of PcrV in the cellular and secreted fractions of biofilms, but not in those of planktonic cells. We also detected the type III effector proteins ExoS and ExoT in the biofilm effluent, but not in the supernatants of planktonic cells. Biofilm formation and type III secretion are therefore not mutually exclusive in P. aeruginosa, and biofilms could play a more active role in virulence than previously thought.

Interrelationships between colonies, biofilms, and planktonic cells of Pseudomonas aeruginosa

Pseudomonas aeruginosa is a gram-negative bacterium and an opportunistic human pathogen that causes chronic infections in immunocompromised individuals. These infections are hard to treat, partly due to the high intrinsic resistance of the bacterium to clinically used antibiotics and partly due to the formation of antibiotic-tolerant biofilms. The three most common ways of growing bacteria in vitro are as planktonic cultures, colonies on agar plates, and biofilms in continuous-flow systems. Biofilms are known to express genes different from those of planktonic cells, and biofilm cells are generally believed to closely resemble planktonic cells in stationary phase. However, few, if any, studies have examined global gene expression in colonies. We used a proteomic approach to investigate the interrelationships between planktonic cells, colonies, and biofilms under comparable conditions. Our results show that protein profiles in colonies resemble those of planktonic cells. Furthermore, contrary to what has been reported previously, the protein profiles of biofilms were found to more closely resemble those of exponentially growing planktonic cells than those of planktonic cells in the stationary phase. These findings raise some intriguing questions about the true nature of biofilms.

The success of routine MRSA screening in vascular surgery: a nine year review

AIM

Methicillin resistant Staphylococcus aureus (MRSA) infection in vascular patients is associated with increased morbidity and mortality. We investigated whether routine MRSA screening reduced complications related to MRSA infection.

METHODS

Data was analysed for all MRSA positive (+ve) vascular patients admitted before (1996-2000) and after (2001-2004) routine MRSA screening was introduced. Outcome measures compared included wound infection, major limb amputation and mortality rates.

RESULTS

There were 92 and 188 MRSA +ve patients in the pre- and postscreening periods, respectively. After the introduction of MRSA screening, MRSA wound infection in MRSA +ve elective admissions was significantly reduced from 55.6% (20/36) to 22.4% (15/67), (P=0.002, chi2 test); amputations were reduced from 27.8% (10/36) to 9% (6/67), P value 0.026, and mortality from 16.7% (6/36) to 9% (6/67), P value >0.05. In MRSA +ve emergency admissions wound infection was significantly reduced from 62.5% (35/56) to 43.8% (53/121), P value 0.042, amputations from 50% (28/56) to 38.8% (47/121), P value 0.26, and mortality from 25% (14/56) to 12.4% (15/121), P value 0.067.

CONCLUSIONS

While the incidence of MRSA infection continues to rise, we have successfully demonstrated that MRSA screening identifies patients at risk of serious complications and is associated with a reduction in these complications following both elective and emergency surgery. Routine screening of all vascular admissions should be part of the strategy to combat MRSA infection.

Is it possible to predict outcome in MRSA positive patients undergoing arterial reconstruction?

AIM

There is an increasing incidence of methicillin resistant Staphylococcus aureus (MRSA) following vascular surgery, which is associated with poor outcome. The risk factors and timing for MRSA acquisition have been established. We attempt to establish predictors of outcome in MRSA positive patients undergoing arterial reconstruction.

METHODS

Eighty-five MRSA positive patients who underwent arterial surgery were grouped according to outcome: good outcome group (successful revascularisation) or poor outcome group (major limb amputation or death). Seven variables were compared: age, gender, renal function, co-morbidity, positive swab site, incision site and second revascularisation surgery.

RESULTS

Increased MRSA incidence from 1.1% to 4.6% of total admissions was highlighted over a 6 year period. When good (n=40) and poor (n=45) outcome groups were compared, no statistically significant differences were identified for the variables listed above, but a second revascularisation operation was 3 times more likely to be associated with poor outcome (P=0.09). Categorising gender and age groups suggests that male gender and age over 75 years was more likely to be associated with poor outcome (odds ratio 0.77). The results also suggest that patients having surgery involving a groin incision do worse than those who do not. One year survival of MRSA positive patients who had successful revascularisation was 90% and a significant number had MRSA eradicated.

CONCLUSIONS

Although this study was unable to identify statistically significant predictors of outcome in patients with MRSA undergoing arterial reconstruction, almost half had a positive outcome. An aggressive detection and eradication policy is clearly indicated.

Purification and characterization of a metacestode cysteine proteinase from Taenia solium involved in the breakdown of human IgG

Infection of the central nervous system by Taenia solium cysticerci is the cause of human neurocysticercosis, a major neurological infection in the Third World and an emerging infectious disease in the United States. We previously isolated a cysteine proteinase from cysticerci of Taenia crassiceps and demonstrated that it degrades human IgG in vitro. We have now isolated a 48 kDa thiol-dependent proteinase from T. solium. The T. solium enzyme also degrades human IgG, but does not significantly degrade albumin. IgG degradation was inhibited by cysteine proteinase inhibitors, but not significantly by inhibitors of aspartic, serine, or metalloproteinases. The peptide substrate specificity and pH optimum resemble cathepsin L. The Km for the peptide substrate Z-Phe-Arg-AFC was calculated to be 7.0 x 10(-6) M, the Kcat was 1.98 x 10(-5) s(-1), and the Kcat/Km 2.84 x 10(9) M(-1) s(-1), a value which is within the diffusion control limit for highly catalytic enzymes. We propose that immunoglobulin degradation by the T. solium cysteine proteinase may play a key role in the host-parasite interface and could be employed as a target for chemotherapy.

Screening men for aortic aneurysm

AIM

Ruptured abdominal aortic aneurysm (rAAA) accounts for 10000 deaths annually in the UK. Deaths occur in the 6th and 7th decades with loss of potential years of life. Mortality rates of 5% to 8% are reported for elective AAA repair, but no significant improvement in emergency outcome, with community mortality remaining at 80% and operative mortality at 50%. Patients surviving have several years life expectancy, regardless of age, and good quality of life. The difference suggests that overall emergency mortality could be significantly reduced by earlier diagnosis with widespread screening of the at risk population. Previous studies suggest screening men over 65 years significantly reduces incidence of rupture and aneurysm related death. Patients with abdominal aortic aneurysm (AAA) have a high prevalence of coronary artery disease (CAD) and vice versa. There is mounting evidence that screening men for AAA reduces rAAA mortality, especially in high-risk groups. A limited screening study of CABG patients was introduced.

METHODS

Patients on the waiting list for coronary artery bypass grafting (CABG) (n=118) had a single duplex scan of the abdominal aorta. Aortic diameter of >2.6 cm was considered abnormal.

RESULTS

Eighteen AAAs were detected (15.3%), 5 required surgery, 13 underwent surveillance. Mean age at detection was 64.8 years with a range of ages between 60 and 72 years.

CONCLUSION

Patients with symptomatic CAD have a high incidence of AAA, with significant risk of rupture in the perioperative period post-CABG. Screening should form part of the routine work-up for coronary revascularisation. Staged repair should be considered with AAA greater than 5.5 cm diameter.

Ruptured abdominal aortic aneurysm. Is it possible to predict outcome?

AIM

Mortality after ruptured abdominal aortic aneurysm (rAAA) remains high. Hardman et al. suggested that the following factors predict perioperative death: age >76 years, loss of consciousness, ECG confirmed ischemia, creatinine over 180 micromol/l and hemoglobin below 9 g/dl. A score of 3 or more had 100% mortality. A retrospective study was performed to validate this and determine if modification is required.

METHODS

Retrospective analysis of the 5 Hardman Index factors along with preoperative systolic blood pressure at presentation, after resuscitation and during surgery was performed.

RESULTS

A total of 137 cases were reviewed with overall mortality of 56.2%. Of Hardman's criteria: age, ECG ischemic changes, creatinine and hemoglobin levels were significant in predicting outcome (p=0.0007, 0.0152, 0.0001 and 0.0213, respectively). Loss of consciousness was not significant (p=0.9054). Hardman scores of 0, 1, 2, 3, and 4 scored mortality percentages of 40.4%, 46.4%, 76.7%, 91.7% and 100%, respectively. Systolic blood pressure was significantly predictive at 100 mmHg and 120 mmHg on presentation (p=0.0008 and 0.0017, respectively) and 100 mmHg and 120 mmHg after resuscitation (p=0.0001 and 0.0510, respectively). A modified score replaced loss of consciousness with systolic blood pressure below 100 mmHg with scores of 0, 1, 2, 3, and 4 had mortality of 22.2%, 46.8%, 66.7%, 83.9% and 100%, respectively.

CONCLUSION

Our data supports the effectiveness of the Hardman Index in predicting successful surgery. However loss of consciousness was not a significant predictor. We proposed review of predictive indices, but resources should be channelled into screening to prevent rAAA.

Subfascial endoscopic perforator surgery: a review

Approximately 1-2% of the UK population suffers from venous ulcers. Incompetent perforator leg veins are thought to be a major contributory factor. Subfascial endoscopic perforator surgery treats incompetent perforators in a minimally invasive fashion with significant improvement in wound healing and reduction in ulcer recurrence rates.

Halogenated furanones from the red alga, Delisea pulchra, inhibit carbapenem antibiotic synthesis and exoenzyme virulence factor production in the phytopathogen Erwinia carotovora

The plant pathogen Erwinia carotovora regulates expression of virulence factors and antibiotic production via an N-3-oxohexanoyl-L-homoserine lactone (3-oxo-C6-HSL) dependent quorum sensing mechanism. The marine alga Delisea pulchra produces halogenated furanones known to antagonise 3-oxo-C6-HSL activity. We have tested the effects of a halogenated furanone on the production of carbapenem, cellulase and protease in E. carotovora. Despite differences in the regulatory mechanisms controlling carbapenem and exoenzyme production each was inhibited by the algal metabolite. We present evidence to suggest that the furanone dependent inhibition of carbapenem production is a result of the disruption of the 3-oxo-C6-HSL dependent expression of the carABCDEFGH operon.

Novel enzyme activities and functional plasticity revealed by recombining highly homologous enzymes

BACKGROUND

Directed evolution by DNA shuffling has been used to modify physical and catalytic properties of biological systems. We have shuffled two highly homologous triazine hydrolases and conducted an exploration of the substrate specificities of the resulting enzymes to acquire a better understanding of the possible distributions of novel functions in sequence space.

RESULTS

Both parental enzymes and a library of 1600 variant triazine hydrolases were screened against a synthetic library of 15 triazines. The shuffled library contained enzymes with up to 150-fold greater transformation rates than either parent. It also contained enzymes that hydrolyzed five of eight triazines that were not substrates for either starting enzyme.

CONCLUSIONS

Permutation of nine amino acid differences resulted in a set of enzymes with surprisingly diverse patterns of reactions catalyzed. The functional richness of this small area of sequence space may aid our understanding of both natural and artificial evolution.

A randomized study to evaluate the effect of a perioperative infusion of dopexamine on colonic mucosal ischemia after aortic surgery

PURPOSE

Colonic ischemia after aortic surgery is associated with increased mortality and morbidity rates. This study was conducted as a single-center side arm to a multicenter, randomized, placebo-controlled study to evaluate the effect of dopexamine hydrochloride on its incidence.

METHODS

Thirty patients, mean age 65.1 years (range, 46-84), undergoing elective infrarenal aortic surgery were entered. Preoperative hemodynamic and respiratory parameters were optimized. Patients were then randomly assigned to receive a perioperative infusion of dopexamine at 2 microg/kg per minute (n = 12) or 0.9% saline placebo (n = 18). All patients underwent colonoscopy and biopsy preoperatively and 1 week postoperatively. Specimens were assessed for evidence of mucosal ischemia, presence of mast cell tryptase, myeloperoxidase activity, and both the inducible and endothelial isoforms of nitric oxide synthase.

RESULTS

There was no significant difference in perioperative fluid and blood requirements or hemodynamic and respiratory parameters between the two groups. However, there was significantly less evidence of mucosal ischemic changes in dopexamine-treated patients (n = 1) compared with placebo (n = 8) (P =.049). Furthermore, when preoperative biopsies were compared with those performed 1 week postoperatively, nine (50%) patients in the placebo group and two (16.7%) in the dopexamine group scored worse. Although there was no significant difference in inflammatory markers between the two groups, both mast cell tryptase and myeloperoxidase expression were increased in patients with histologic evidence of ischemia (P <.05). Furthermore, inducible nitric oxide synthase staining within the vascular (P =.001) and lamina propria (P <.05) components of the mucosa was also significantly greater.

CONCLUSION

A perioperative dopexamine infusion affords significant histologic protection to colonic mucosa after aortic surgery.