The top 100 most cited articles on artificial intelligence in radiology: a bibliometric analysis

AIM

To identify the most influential publications relating to artificial intelligence (AI) in radiology in order to identify current trends in the literature and to highlight areas requiring further research.

MATERIALS AND METHODS

A retrospective bibliometric analysis was performed of the top 100 most cited articles on this topic. Data pertaining to year of publication, publishing journal, journal impact factor, authorship, article title, institution, country, type of article, article subject, and keywords were collected.

RESULTS

The number of citations per article for the top 100 list ranged from 254 to 3,576 (median 353). The number of citations per year, per article ranged from 10.4 to 894 (median 65.6). The majority of articles (n=62) were published within the last 10 years. The USA was the most common country of origin (n=44). The journal with the greatest number of articles was IEEE Transactions On Medical Imaging (n=38). University Medical Center Utrecht contributed the greatest number of articles (n=6). There were 92 original research articles, 52 of which were clinical studies. The most common clinical subjects were neuroimaging (n=25) and oncology (n=16). The most common keyword used was "deep learning" (n=34).

CONCLUSION

This study provides an in-depth analysis of the top 100 most-cited papers on the use of AI in radiology. It also provides researchers with detailed insight into the current influential papers in this field, the characteristics of those studies, as well as potential future trends in this fast-developing area of radiology.

Detailed analysis of in-hospital transmission of SARS-CoV-2 using whole genome sequencing

BACKGROUND

Hospital transmission of SARS-CoV-2 has proved difficult to control, with healthcare-associated infections troublesome throughout.

AIM

To understand factors contributing to hospital transmission of infections, which is necessary for containing spread.

METHODS

An outbreak of 56 staff and patient cases of COVID-19 over a 31-day period in a tertiary referral unit is presented, with at least a further 29 cases identified outside of the unit and the hospital by whole genome sequencing (WGS).

FINDINGS

Transmission is documented from staff to staff, staff to patients, and patients to staff, showing disruption of a tertiary referral service, despite implementation of nationally recommended control measures, superior ventilation, and use of personal protective equipment. There was extensive spread from the index case, despite this patient spending only 10 h bed bound on the ward in strict cubicle isolation and with an initial single target low level (C_T = 32) polymerase chain reaction test.

CONCLUSION

This investigation highlights how effectively and rapidly SARS-CoV-2 can spread in certain circumstances. It raises questions about infection control measures in place at the time and calls into question the premise that transmissibility can be reliably detected by using lower sensitivity rapid antigen lateral flow tests. We also highlight the value of early intervention in reducing impact as well as the value of WGS in understanding outbreaks.

Prenatal findings and associated survival rates in fetal ventriculomegaly: A prospective observational study

OBJECTIVES

Fetal ventriculomegaly is associated with varying degrees of genetic and structural abnormalities. The objective was to present the experience of fetal ventriculomegaly in a large European center in relation to: 1. grade of ventriculomegaly; 2. additional chromosomal/structural abnormalities; and 3. perinatal survival rates.

METHODS

This was a prospective observational study of patients referred with fetal ventriculomegaly from January 2011 to July 2020. Data were obtained from the hospital database and analyzed to determine the rate of isolated ventriculomegaly, associated structural abnormalities, chromosomal/genetic abnormalities, and survival rates. Data were stratified into three groups; mild (Vp = 10-12 mm), moderate (Vp = 13-15 mm) and severe (Vp > 15 mm) ventriculomegaly.

RESULTS

There were 213 fetuses included for analysis. Of these 42.7% had mild ventriculomegaly, 44.6% severe and 12.7% had moderate ventriculomegaly. Initial ultrasound assessment reported isolated ventriculomegaly in 45.5% fetuses, with additional structural abnormalities in 54.5%. The rate of chromosomal/genetic abnormalities was high,16.4%. After all investigations, the true rate of isolated VM was 36.1%. The overall survival was 85.6%. Survival was higher for those with isolated VM across all groups (P < 0.05).

CONCLUSION

Ventriculomegaly is a complex condition and patients should be counselled that even with apparently isolated VM, there remains the possibility of additional genetic and/or structural problems being diagnosed in up to 10% of fetuses.

COVID-19 mRNA vaccine BNT162b2 induces autoantibodies against type I interferons in a healthy woman

Coronavirus disease (COVID-19) caused by SARS-CoV-2 virus is associated with a wide range of clinical manifestations, including autoimmune features and autoantibody production in a small subset of patients. Pre-exiting neutralizing autoantibodies against type I interferons (IFNs) are associated with COVID-19 disease severity. In this case report, plasma levels of IgG against type I interferons (IFNs) were increased specifically among the 103 autoantibodies tested following the second shot of COVID-19 vaccine BNT162b2 compared to pre-vaccination and further increased following the third shot of BNT162b2 in a healthy woman. Unlike COVID-19 mediated autoimmune responses, vaccination in this healthy woman did not induce autoantibodies against autoantigens associated with autoimmune diseases. Importantly, IFN-α-2a-induced STAT1 responses in human PBMCs in vitro were suppressed by adding plasma samples from the study subject post- but not pre-vaccination. After the second dose of vaccine, the study subject exhibited severe dermatitis for about six months and responded to treatments with Betamethasone Dipropionate Ointment and antihistamines for about one month. Immune responses to type I IFN can be double-edged swords in enhancing vaccine efficacy and immune responses to infectious diseases, as well as accelerating chronic disease pathogenesis (e.g., chronic viral infections and autoimmune diseases). This case highlights the BNT162b2-induced neutralizing anti-type I IFN autoantibody production, which may affect immune functions in a small subset of general population and patients with some chronic diseases.

STRategies to manage Emergency ambulance Telephone Callers with sustained High needs: an Evaluation using linked Data (STRETCHED) - a study protocol

INTRODUCTION

UK ambulance services have identified a concern with high users of the 999 service and have set up 'frequent callers' services, ranging from within-service management to cross-sectoral multidisciplinary case management approaches. There is little evidence about how to address the needs of this patient group.

AIM

To evaluate effectiveness, safety and efficiency of case management approaches to the care of people who frequently call the emergency ambulance service, and gain an understanding of barriers and facilitators to implementation.

OBJECTIVES

(1) Develop an understanding of predicted mechanisms of change to underpin evaluation. (2) Describe epidemiology of sustained high users of 999 services. (3) Evaluate case management approaches to the care of people who call the 999 ambulance service frequently in terms of: (i) Further emergency contacts (999, emergency department, emergency admissions to hospital) (ii) Effects on other services (iii) Adverse events (deaths, injuries, serious medical emergencies and police arrests) (iv) Costs of intervention and care (v) Patient experience of care. (4) Identify challenges and opportunities associated with using case management models, including features associated with success, and develop theories about how case management works in this population.

METHODS AND ANALYSIS

We will conduct a multisite mixed-methods evaluation of case management for people who use ambulance services frequently by using anonymised linked routine data outcomes in a 'natural experiment' cohort design, in four regional ambulance services. We will conduct interviews and focus groups with service users, commissioners and emergency and non-acute care providers. The planned start and end dates of the study are 1 April 2019 and 1 September 2022, respectively ETHICS AND DISSEMINATION: The study received approval from the UK Health Research Authority (Confidentiality Advisory Group reference number: 19/CAG/0195; research ethics committee reference number: 19/WA/0216).We will collate feedback from our Lived Experience Advisory Panel, the Frequent Caller National Network and Research Management Group for targeted dissemination activities.

Severe fetal ventriculomegaly: Fetal morbidity and mortality, caesarean delivery rates and obstetrical challenges in a large prospective cohort

INTRODUCTION

Severe fetal ventriculomegaly (VM) is defined as an enlargement of the atria of the lateral cerebral ventricles (Vp) of greater than 15 mm. While it is well established that it confers significant risk of morbidity and mortality to the neonate, there is limited information pertaining to the caesarean delivery rates and the obstetric management of these complex cases. The aim of this study was twofold: firstly, to determine survival rates in fetuses with severe VM, and secondly to determine the caesarean delivery rates in continuing pregnancies. We explore the obstetric challenges associated with these difficult cases.

METHODS

This was a prospective observational study of patients with antenatal severe VM, attending the Department of Fetal Medicine, National Maternity Hospital, Dublin, Ireland, from 1st January 2011 to 31st July 2020. Data were obtained from the hospital database and those with severe VM (Vp > 15 mm) were identified. The rates of chromosomal abnormalities, the survival rates and the caesarean delivery (CD) rates for the overall group were then determined. The data were then further sub-divided into two groups: 1. Vp < 20 mm and 2. Vp > 20 mm, and the results compared. Statistical analysis was performed using the Chi-Square test.

RESULTS

A total of N = 95 pregnancies with severe VM were included for analysis, of which additional structural abnormalities on ultrasound were apparent in 67/95 (70.5%) and 28/95 (29.5%) had isolated severe VM. Chromosomal abnormalities were diagnosed in 15/95 (15.8%) of cases, with (2/28) 7.1% in the isolated SVM group versus (13/67) 19.4% in the non-isolated SVM group. The overall survival rate (excluding TOP) was 53/74 (71.6%), with 20/23 (86.9%) in the isolated SVM group. The overall CD rate was 47/72 (65.3%), which was significantly higher than the CD for the hospital during the same time period of 25.4% (P < 0.01). The data were subdivided into Vp < 20 and Vp > 20 and those with a Vp > 20 had higher rates of additional intracranial findings on ultrasound (Vp < 20 13/41 (31.7%) versus Vp > 20 32/54 (59.3%) (P < 0.05)) and macrocrania (Vp < 20 14/41 (34.1%) versus Vp > 20 35/54 (64.8%) (P < 0.05)). No significant difference was observed in the overall survival or CD rates between the two groups.

CONCLUSION

In conclusion this study reports significant fetal morbidity and mortality with severe VM with high CD rates observed in this cohort. Significant challenges exist in relation to the obstetric management and counseling of parents regarding an often uncertain neonatal prognosis. In continuing pregnancies with significant macrocrania delivery plans should be individualized to improve neonatal outcomes where possible and minimize harm to the mother.

170 Social and Environmental Benefits of Virtual Fracture Clinics in Trauma and Orthopaedic Surgery: Reduced Patient Travel Time, Patient Cost and Air Pollutant Emissions

Aim

Several papers have analysed the clinical benefits and safety of Virtual Fracture Clinics (VFCs). A significant increase in the use of Trauma and Orthopaedic (T&O) VFCs was seen during the COVID-19 pandemic. This study aims to investigate the social impact of VFCs on the travel burden and travel costs of T&O patients, as well as the potential environmental benefits in relation to fuel consumption and travel-related pollutant emissions.

Method

All patients referred for T&O VFC review from March 2020 to June 2020 were retrospectively analysed. The travel burden and environmental impacts of hypothetical face-to-face consultations were compared with these VFC reviews. The primary outcomes measured were patient travel time saved, patient travel distance saved, patient cost savings and reduction in air-pollutant emissions.

Results

Over a four-month period, 1359 VFC consultations were conducted. The average travel distance saved by VFC review was 88.6 kilometres (range 3.3-615), with an average of 73 minutes (range 9-390) of travel-time saved. Patients consumed, on average, 8.2 litres (range 0.3-57.8) less fuel and saved an average of €11.02 (range 0.41-76.59). The average reduction in air-pollutant vehicle emissions, including carbon dioxide, carbon monoxide, nitric oxides and volatile organic compounds was 20.3 kilograms (range 0.8-140.8), 517.3 grams (g) (range 19.3-3592.3), 38.1g (range 1.4-264.8) and 56.9g (range 2.1-395.2), respectively.

Conclusions

VFCs reduce patient travel distance, travel time and travel costs. In addition, VFCs confer significant environmental benefits through reduced fuel consumption and reduction of harmful environmental emissions.

The Natural History of Trisomy 21: Outcome Data from a Large Tertiary Referral Centre

OBJECTIVE

The aim of the study was to prospectively gather data on pregnancy outcomes of prenatally diagnosed trisomy 21 (T21) in a large tertiary referral centre.

METHODS

Data were gathered prospectively in a large tertiary referral centre over 5 years from 2013 to 2017 inclusively. Baseline demographic and pregnancy outcome data were recorded on an anonymized computerized database.

RESULTS

There were 1,836 congenital anomalies diagnosed in the study period including 8.9% (n = 165) cases of T21. 79% (n = 131) were age 35 or older at diagnosis. 79/113 (69.9%) women chose a termination of pregnancy (TOP) following a diagnosis of T21. Amongst pregnancies that continued, there were 4 second-trimester miscarriages (4/34, 11.7%), 9 stillbirths (9/34, 26.4%), and 1 neonatal death, giving an overall pregnancy and neonatal loss rate of 14/34 (41.1%).

CONCLUSION

The risk of foetal loss in prenatally diagnosed T21 is high at 38% with an overall pregnancy loss rate of 41.1%. This information may be of benefit when counselling couples who are faced with a diagnosis of T21 particularly in the context of limited access to TOP.

05 Co-design of a logic model describing components, mechanisms of change and expected impacts of case management for people who frequently call ambulance services

Background

Multi-agency case management is being introduced by ambulance services and their partners in the UK to try to identify and address the needs of those who call 999 ambulance services frequently. However, there is a lack of evidence about what works well in this setting and how. Based on current nationally agreed definitions, calling frequently is defined as 5 or more times in a month, or 12 or more times in a three-month period. The STRETCHED study (STRategies to manage Emergency ambulance Telephone Callers with sustained High needs – an Evaluation using linked Data) study seeks to evaluate clinical and cost-effectiveness, safety, and efficiency of case management for people who frequently call the emergency ambulance service.

We developed a logic model to describe key components, mechanisms of change and expected impacts of cross-sectoral case management approaches to the management of people who call 999 frequently.

Method

We conducted a stakeholder event with 37 people from Wales, England and Northern Ireland including patient representatives and professional staff involved in commissioning, planning and delivering case management for people who call 999 services frequently. The aggregated responses from the participants was used as the basis for developing a logic model.

Results

Components: dedicated staff time for case management, availability and knowledge of relevant services for referral, multidisciplinary collaboration, organisational support, and clear information sharing protocols

Mechanisms: provision of space for a clear understanding of reasons for calling, tailoring of multi–sectoral management to individual needs, offering therapeutic support and assistance in development of self–efficacy

Impacts: improvement in access to appropriate and timely care, increase in efficiency and accessibility of the healthcare system, reduction in emergency calls, costs and mortality

Conclusion

Case management is a developing area of provision in prehospital emergency care for people who call ambulance services frequently. Our logic model provides a firm foundation for evaluation to build the urgently needed evidence base for case management of people who call ambulance services frequently.

Diagnostic Limitations in Congenital Zika Virus Infection

This is the first documented case of an infant with congenital Zika virus infection (ZVI) born in Ireland. A term infant was delivered with an antenatal diagnosis of severe microcephaly. First trimester bloods confirmed maternal ZVI and although the infant did not have Zika virus RNA or Zika-specific IgM in her blood or urine, she had multiple clinical features of congenital ZVI and Zika virus RNA was present in the placenta.

Patient deprivation and perceived scan burden negatively impact the quality of whole-body MRI

AIM

To evaluate the association between the image quality of cancer staging whole-body magnetic resonance imaging (WB-MRI) and patient demographics, distress, and perceived scan burden.

MATERIALS AND METHODS

A sample of patients recruited prospectively to multicentre trials comparing WB-MRI with standard scans for staging lung and colorectal cancer were invited to complete two questionnaires. The baseline questionnaire, administered at recruitment, collated data on demographics, distress and co-morbidity. The follow-up questionnaire, completed after staging investigations, measured perceived WB-MRI scan burden (scored 1 low to 7 high). WB-MRI anatomical coverage, and technical quality was graded by a radiographic technician and grading combined to categorise the scan as "optimal", "sub-optimal" or "degraded". A radiologist categorised 30 scans to test interobserver agreement. Data were analysed using the chi-square, Fisher's exact, t-tests, and multinomial regression.

RESULTS

One hundred and fourteen patients were included in the study (53 lung, 61 colorectal; average age 65.3 years, SD=11.8; 66 men [57.9%]). Overall, 45.6% (n=52), scans were classified as "optimal" quality, 39.5% (n=45) "sub-optimal", and 14.9% (n=17) as "degraded". In adjusted analyses, greater deprivation level and higher patient-reported scan burden were both associated with a higher likelihood of having a sub-optimal versus an optimal scan (odds ratio [OR]: 4.465, 95% confidence interval [CI]: 1.454 to 13.709, p=0.009; OR: 1.987, CI: 1.153 to 3.425, p=0.013, respectively). None of the variables predicted the likelihood of having a degraded scan.

CONCLUSIONS

Deprivation and patients' perceived experience of the WB-MRI are related to image quality. Tailored protocols and individualised patient management before and during WB-MRI may improve image quality.

Recovery of S. Epidermidis and E. Coli from Effluent Peritoneal Dialysate

The effect of incubation temperature and duration was studied on the growth of organisms in peritoneal dialysate effluent. Penicillin-sensitive, and gentamicin sensitive clinical isolates of S. epidermidis (SE} and E. Coli (EC}, respectively, were inoculated into freshly drained dialysate of 19 CAPD patients who did not have peritonitis. Each dialysate was 1.5% dextrose in strength and had a minimum dwell of 6 hours. Control and test aliquots were incubated at 4°C, 20°C and 37°C for periods of up to 12 hours, and samples collected and plated to determine colony counts. Initial counts at time zero were 9.4 × 104 (SE} and 6.6 × 103 (EC} CFUlml. SE showed no change in count at 4 or 20°C up to 12 hours. There was a significant increase (p<0.005} at 37°C, at 12 hours to 1.72 × 106 CFUlml. EC showed no change at 4 or 20°C. There was a significant decrease in count for EC at 37°C, 6 hours (5.5 × 102 CFUlml, p<0.01} and 37°, 12 hours (2.9 × 102 CFUlml, p<0.0001}. It is recommended that infected dialysate should be stored in cool conditions until it can be transported for culture to ensure adequate recovery of gram negative organisms.

InFORM: Improving care for people who Frequently call 999: co-production of guidance through an Observational study using Routine linked data and Mixed methods

BackgroundPeople who frequently call the 999 ambulance service present an operational challenge to providers and their needs are inadequately met by current service provision. Aim of researchTo understand patterns and health outcomes of frequent calling and to work with stakeholders to co-produce guidance for formal testing in a future evaluation. MethodsThis mixed methods study will include a scoping review of national and international literature followed by an epidemiological study of callers at the all Wales level exploring health outcomes through anonymised linked data. We will also explore the views of patients using qualitative Bio-photographic interview method with a follow up interview at six months and use focus groups with care providers from across primary and emergency care and the third sector. We will use generalised linear model to analyse quantitative data and qualitative data will be analysed thematically. ResultsFindings will include follow up of eligible patients; successful data matching and data linkage; retrieval of outcomes within 12 months. Outcomes will include: adverse events, deaths, emergency admissions; 999 attendances. Qualitative results will include Bio-photographic interviews with completed scrap books and interviews based on the books (n=34). Care provider focus groups (n= 22). Output Co-produced guidance developed with stakeholders. ConclusionHigh users of the 999-ambulance represent a significant policy challenge to emergency ambulance services and often present with complex needs. This study will inform on the characteristics of callers and how to address their care supported with a co-produced guidance for care providers.

PP31 Strategies to manage emergency ambulance telephone callers with sustained high needs – an evaluation using linked data (STRETCHED)

Background

Ambulance services across the UK have recognised a clinical and operational problem with persistent high users of the 999 service, but there is a lack of evidence about what works in this setting and how. We aim to evaluate the effectiveness, safety and efficiency of multi-agency case management approaches to the care of people who frequently call the emergency ambulance service, and gain understanding of barriers and facilitators to implementation.

Methods

We will carry out a mixed methods evaluation using anonymised linked routine data outcomes in a ‘natural experiment’ cohort design in four UK ambulance services, with one case management intervention site and one control site within each service. We will describe the epidemiology of ‘frequent calling’; assess the effects of case management on process, outcomes, safety and costs up to six months for 300 high users per service (n-1200); and examine the views of stakeholders, including patients, through qualitative methods. We will synthesise quantitative and qualitative findings, informed by a logic model describing predicted mechanisms of change.

Results

We received confirmation of NIHR grant funding for this study in 2018 so do not yet have results to report.

Conclusions

Telephone callers with sustained high needs represent a significant, high profile policy challenge to emergency ambulance services. Such callers may be indicative of gaps elsewhere in the health care system, which could be more effectively addressed by pro-active care. The STRETCHED study provides the opportunity to contribute to the currently sparse evidence base on interventions for this patient group.

Engineering an anti-CD52 antibody for enhanced deamidation stability

Deamidation evaluation and mitigation is an important aspect of therapeutic antibody developability assessment. We investigated the structure and function of the Asn-Gly deamidation in a human anti-CD52 IgG1 antibody light chain complementarity-determining region 1, and risk mitigation through protein engineering. Antigen binding affinity was found to decrease about 400-fold when Asn³³ was replaced with an Asp residue to mimic the deamidation product, suggesting significant impacts on antibody function. Other variants made at Asn³³ (N33H, N33Q, N33H, N33R) were also found to result in significant loss of antigen binding affinity. The co-crystal structure of the antigen-binding fragment bound to a CD52 peptide mimetic was solved at 2.2Å (PDB code 6OBD), which revealed that Asn³³ directly interacts with the CD52 phosphate group via a hydrogen bond. Gly³⁴, but sits away from the binding interface, rendering it more amendable to mutagenesis without affecting affinity. Saturation mutants at Gly³⁴ were prepared and subjected to forced deamidation by incubation at elevated pH and temperature. Three mutants (G34R, G34K and G34Q) showed increased resistance to deamidation by LC-MS peptide mapping, while maintaining high binding affinity to CD52 antigen measured by Biacore. A complement -dependent cytotoxicity assay indicated that these mutants function by triggering antibody effector function. This study illustrates the importance of structure-based design and extensive mutagenesis to mitigate antibody developability issues.

A Life-Saving Palsy: Hereditary Neuropathy with Liability to Pressure Palsies (HNPP) Presenting As Hand Weakness during Cardiopulmonary Resuscitation (CPR) Training

Aim To describe a case of acute and transient hand weakness that developed during cardiopulmonary resuscitation (CPR) training. Hereditary neuropathy with liability to pressure palsies (HNPP) should be considered in patients with recurrent, painless motor or sensory neuropathies at sites of peripheral nerve compression. Methods Nerve conduction studies confirmed neuropraxia of the distal ulnar nerve with a mild background demyelinating peripheral neuropathy. Results A positive family history emerged and HNPP was confirmed by genetic testing. HNPP is most reliably diagnosed by molecular testing for peripheral myelin protein 22 (PMP22) gene deletion or point mutation on chromosome 17p11.2. Conclusion CPR, a procedure carried out by medical professionals on a daily basis, is a high-energy manual task and provides multiple opportunities for nerve compression. This case demonstrates the importance of having a high index of clinical suspicion of this disorder in patients. Recognising a diagnosis of HNPP may prevent unnecessary surgical decompression.

The involvement of older inpatients in medical student education

Objectives

To examine older inpatients’ experiences with medical student education, their views on future interactions, and to seek their opinion on the most important curricular topics related to geriatric medicine.

Methods

The study involved 112 non-confused inpatients older than 65 years of age, who completed a uniformed questionnaire on the day of their discharge from a teaching hospital.

Results

The mean age was 81 years, with equal number of male and female participants. 57% interacted with the students during their admission, the majority being interviewed and examined. Almost all (92%) of these patients described their experience as positive, some described it as time-consuming (23%), repetitive (19%) and tiresome (9%). 92% of all participants agreed that the older patients should be part of medical students’ education. Dementia, cardiac conditions, cancer, arthritis, isolation/loneliness were highlighted as the most important topics to teach medical students related to geriatric medicine, while patience and listening were listed as important skills. They suggested practical, easily implemented advice for the improvement of the interaction between students and older patients; including allowing more time for interactions and for students to speak louder.

Conclusions

Older patients felt positively about their interactions with medical students, and believed that older patients should be involved in medical student education. As well as medical conditions such as dementia, cardiac disease and cancer, these patients highlighted isolation and loneliness as important topics for undergraduate geriatric medical education, implying that students should learn about broader aspects of older patients’ health and wellbeing.

Metal worker's lung: spatial association with Mycobacterium avium

BACKGROUND

Outbreaks of hypersensitivity pneumonitis (HP) are not uncommon in workplaces where metal working fluid (MWF) is used to facilitate metal turning. Inhalation of microbe-contaminated MWF has been assumed to be the cause, but previous investigations have failed to establish a spatial relationship between a contaminated source and an outbreak.

OBJECTIVES

After an outbreak of five cases of HP in a UK factory, we carried out blinded, molecular-based microbiological investigation of MWF samples in order to identify potential links between specific microbial taxa and machines in the outbreak zone.

METHODS

Custom-quantitative PCR assays, microscopy and phylogenetic analyses were performed on blinded MWF samples to quantify microbial burden and identify potential aetiological agents of HP in metal workers.

MEASUREMENTS AND MAIN RESULTS

MWF from machines fed by a central sump, but not those with an isolated supply, was contaminated by mycobacteria. The factory sump and a single linked machine at the centre of the outbreak zone, known to be the workstation of the index cases, had very high levels of detectable organisms. Phylogenetic placement of mycobacterial taxonomic marker genes generated from these samples indicated that the contaminating organisms were closely related to Mycobacterium avium.

CONCLUSIONS

We describe, for the first time, a close spatial relationship between the abundance of a mycobacterium-like organism, most probably M. avium, and a localised outbreak of MWF-associated HP. The further development of sequence-based analytic techniques should assist in the prevention of this important occupational disease.

X-ray and biochemical analysis of N370S mutant human acid β-glucosidase

Gaucher disease is caused by mutations in the enzyme acid β-glucosidase (GCase), the most common of which is the substitution of serine for asparagine at residue 370 (N370S). To characterize the nature of this mutation, we expressed human N370S GCase in insect cells and compared the x-ray structure and biochemical properties of the purified protein with that of the recombinant human GCase (imiglucerase, Cerezyme®). The x-ray structure of N370S mutant acid β-glucosidase at acidic and neutral pH values indicates that the overall folding of the N370S mutant is identical to that of recombinant GCase. Subtle differences were observed in the conformation of a flexible loop at the active site and in the hydrogen bonding ability of aromatic residues on this loop with residue 370 and the catalytic residues Glu-235 and Glu-340. Circular dichroism spectroscopy showed a pH-dependent change in the environment of tryptophan residues in imiglucerase that is absent in N370S GCase. The mutant protein was catalytically deficient with reduced V(max) and increased K(m) values for the substrate p-nitrophenyl-β-D-glucopyranoside and reduced sensitivity to competitive inhibitors. N370S GCase was more stable to thermal denaturation and had an increased lysosomal half-life compared with imiglucerase following uptake into macrophages. The competitive inhibitor N-(n-nonyl)deoxynojirimycin increased lysosomal levels of both N370S and imiglucerase 2-3-fold by reducing lysosomal degradation. Overall, these data indicate that the N370S mutation results in a normally folded but less flexible protein with reduced catalytic activity compared with imiglucerase.

Use of direct fluorescence labeling and confocal microscopy to determine the biodistribution of two protein therapeutics, Cerezyme and Ceredase

Efficient targeting of therapeutic reagents to tissues and cell types of interest is critical to achieving therapeutic efficacy and avoiding unwanted side effects due to offtarget uptake. To increase assay efficiency and reduce the number of animals used per experiment during preclinical development, we used a combination of direct fluorescence labeling and confocal microscopy to simultaneously examine the biodistribution of two therapeutic proteins, Cerezyme and Ceredase, in the same animals. We show that the fluorescent tags do not interfere with protein uptake and localization. We are able to detect Cerezyme and Ceredase in intact cells and organs and demonstrate colocalization within target cells using confocal microscopy. In addition, the relative amount of protein internalized by different cell types can be quantified using cell type-specific markers and morphometric analysis. This approach provides an easy and straightforward means of assessing the tissue and cell type-specific biodistribution of multiple protein therapeutics in target organs using a minimal number of animals.

Enhancement strategies for Cu(II), Cr(III) and Cr(VI) remediation by a variety of seaweed species

Various chemical treatments have been applied to six brown, red and green seaweed species with a view to enhancing their metal removal for Cu(II), Cr(III) and Cr(VI). Treatment with acetone resulted in the greatest enhancement for both cationic and anionic species with relatively low mass losses (15-35%), indicating its low risk to biomass operational stability. Cation binding was increased by 69%, while the total Cr removal was augmented by 15%. Cr(VI) binding was shown to be an adsorption-coupled reduction, whereby Cr(VI) was bound to the biomass surface at pH 2 and subsequently reduced to Cr(III). Acetone treatment also resulted in biomasses that were capable of converting up to 83% of Cr(VI) in solution to Cr(III). Blocking of carboxyl and amino functionalities had significant negative effects both on total Cr removal as well as percentage conversion of Cr(VI) to Cr(III). Results therefore indicated the significant role played by these moieties in metal binding to these seaweeds. Potentiometric titrations displayed agreement between the degree of esterification and the decrease in Cu(II) removal for Ulva spp. and Polysiphonia lanosa. FTIR analysis identified changes in biomass functionality and availability after chemical modification, the results of which were in agreement with metal removal studies. In conclusion, these biosorbents represent suitable candidates to replace conventional removal technologies for metal bearing wastewaters, in particular for the detoxification of hazardous Cr(VI) waste streams.

A multi-tiered analytical approach for the analysis and quantitation of high-molecular-weight aggregates in a recombinant therapeutic glycoprotein

In this study, we have investigated sedimentation velocity ultracentrifugation (AUC-SV), size exclusion chromatography (SEC), and circular dichroism (CD) methods for the detection and quantitation of protein aggregates using recombinant acid alpha-glucosidase (rhGAA) as a model. The results of this study showed that the formation and molecular weight distribution of rhGAA aggregated species were dependent upon the formulation conditions as well as the storage or stress conditions used to induce aggregation. The utility of CD as a probe for non-native, aggregated species was affirmed, as this method was sensitive to rhGAA aggregation levels of < or = 4%. An extensive evaluation of AUC-SV variability was performed using nine levels of spiked rhGAA aggregate that were analyzed on six occasions. Based on our data, the precision of the AUC-SV results increased with increasing levels of aggregate, with a mean RSD of 37.2%. The limit of quantitation (LOQ) for the AUC-SV method, which was based on a Precision criterion of RSD < 20%, was determined to be > or = 3% aggregated rhGAA. The Precision and LOQ of the SEC method, determined using the same rhGAA sample set, was found to be 3.8% and > or = 0.2%, respectively. In general, there was good agreement between the levels of aggregated rhGAA determined using the AUC-SV and SEC methods, with a slight positive bias noted for the AUC-SV results. These studies emphasize the value of applying multiple, well-characterized analytical tools in the evaluation of therapeutic protein aggregation.

Investigation of dental samples using a 35MHz focussed ultrasound piezocomposite transducer

Dental erosion and decay are increasingly prevalent but as yet there is no quantitative monitoring tool. Such a tool would allow earlier diagnosis and treatment and ultimately the prevention of more serious disease and pain. Despite ultrasound having been demonstrated as a method of probing the internal structures of teeth more than 40 years ago, development of a clinical tool has been slow. The aim of the study reported here was to investigate the use of a novel high frequency ultrasound transducer and validate it using a known dental technique. A tooth extracted for clinical reasons was sectioned to provide a sample that contained an enamel and dentine layer such that the enamel-dentine junction (EDJ) was of a varying depth. The sample was then submerged in water and a B-scan recorded using a custom-designed piezocomposite ultrasound transducer with a centre frequency of 35 MHz and a -6 dB bandwidth of 24 MHz. The transducer has an axial resolution of 180 microm and a spatial resolution of 110 microm, a significant advance on previous work using lower frequencies. The depth of the EDJ was measured from the resulting data set and compared to measurements from the sequential grinding and imaging (SGI) method. The B-scan showed that the EDJ was of varying depth. Subsequently, the EDJ measurements were found to have a correlation of 0.89 (p<0.01) against the SGI measurements. The results indicate that high frequency ultrasound is capable of measuring enamel thickness to an accuracy of within 10% of the total enamel thickness, whereas currently there is no clinical tool available to measure enamel thickness.