Patient centered guidelines for the laboratory diagnosis of Gaucher disease type 1

Gaucher disease (GD) is an autosomal recessive lysosomal storage disorder due to the deficient activity of the acid beta-glucosidase (GCase) enzyme, resulting in the progressive lysosomal accumulation of glucosylceramide (GlcCer) and its deacylated derivate, glucosylsphingosine (GlcSph). GCase is encoded by the GBA1 gene, located on chromosome 1q21 16 kb upstream from a highly homologous pseudogene. To date, more than 400 GBA1 pathogenic variants have been reported, many of them derived from recombination events between the gene and the pseudogene. In the last years, the increased access to new technologies has led to an exponential growth in the number of diagnostic laboratories offering GD testing. However, both biochemical and genetic diagnosis of GD are challenging and to date no specific evidence-based guidelines for the laboratory diagnosis of GD have been published. The objective of the guidelines presented here is to provide evidence-based recommendations for the technical implementation and interpretation of biochemical and genetic testing for the diagnosis of GD to ensure a timely and accurate diagnosis for patients with GD worldwide. The guidelines have been developed by members of the Diagnostic Working group of the International Working Group of Gaucher Disease (IWGGD), a non-profit network established to promote clinical and basic research into GD for the ultimate purpose of improving the lives of patients with this disease. One of the goals of the IWGGD is to support equitable access to diagnosis of GD and to standardize procedures to ensure an accurate diagnosis. Therefore, a guideline development group consisting of biochemists and geneticists working in the field of GD diagnosis was established and a list of topics to be discussed was selected. In these guidelines, twenty recommendations are provided based on information gathered through a systematic review of the literature and two different diagnostic algorithms are presented, considering the geographical differences in the access to diagnostic services. Besides, several gaps in the current diagnostic workflow were identified and actions to fulfill them were taken within the IWGGD. We believe that the implementation of recommendations provided in these guidelines will promote an equitable, timely and accurate diagnosis for patients with GD worldwide.

Artistic and Health Professionals' Perceptions of Training Load Practices in Pre-Professional and Professional Ballet and Contemporary Dance: A Cross-Sectional Survey

This study aimed to investigate the perceptions of training load practices of dance artistic and health professionals. Artistic staff and health professionals with experience in dance were invited to participate in a cross-sectional survey study relating to training load practices in pre-professional and professional, ballet and contemporary dance. The survey was developed from previous investigations in soccer and consisted of multiple-choice, Likert scale, and free-text responses. Responses to closed questions were reported by percentage and 95% confidence intervals (95% CI). Thematic analysis was performed by two independent assessors of free-text responses. There were six artistic staff and 18 health professional participants. Artistic staff were perceived to be "mostly/completely responsible" for planning training (artistic staff: 100%, 95% CI: 61%, 100%; health professionals: 94%, 95% CI: 76%, 100%), with health professionals "mostly/completely responsible" at times of injury (artistic staff: 83%, 95% CI: 41%, 99%; health professionals: 95% CI: 61%, 96%). Both groups reported using individual modification to manage training loads and recognized the benefits of rest. Artistic staff recognized the need to modify training when injured, in line with experience levels, workload, age, and general health. Both groups "agree/strongly agree" that monitoring would be or is useful (artistic staff: 83%, 95% CI: 41%, 99%; health professionals: 95% CI: 61%, 96%). This investigation provides insight into the perceptions of artistic staff and health professionals with experience in dance toward training practices. Artistic staff and health professionals need to work together and adapt monitoring practices to their context to support artistic staff in planning training. The findings guide the implementation of these interventions by understanding potential barriers to their effectiveness that may potentially reduce injury.

Collaborative health systems ECHO: The use of a tele-education platform to facilitate communication and collaboration with recipients of state targeted response funds in Pennsylvania

Background: The opioid epidemic continues to erode communities across Pennsylvania (PA). Federal and PA state programs developed grants to establish Hub and Spoke programs for the expansion of medications for opioid use disorders (MOUD). Employing the telementoring platform Project ECHO (Extension for Community Health Outcomes), Penn State Health engaged the other seven grant awardees in a Collaborative Health Systems (CHS) ECHO. We conducted key informant interviews to better understand impact of the CHS ECHO on health systems collaboration and opioid crisis efforts. Methods: For eight one-hour sessions, each awardee presented their unique strategies, challenges, and opportunities. Using REDCap, program characteristics, such as number of waivered prescribers and number of patients served were collected at baseline. After completion of the sessions, key informant interviews were conducted to assess the impact of CHS ECHO on awardee's programs. Results: Analysis of key informant interviews revealed important themes to address opioid crisis efforts, including the need for strategic and proactive program reevaluation and the convenience of collaborative peer learning networks. Participants expressed benefits of the CHS ECHO including allowing space for discussion of challenges and best practices and facilitating conversation on collaborative targeted advocacy and systems-level improvements. Participants further reported bolstered motivation and confidence. Conclusions: Utilizing Project ECHO provided a bidirectional platform of learning and support that created important connections between institutions working to combat the opioid epidemic. CHS ECHO was a unique opportunity for productive and convenient peer learning across external partners. Open dialogue developed during CHS ECHO can continue to direct systems-levels improvements that benefit individual and population outcomes.

Frailty Is Associated with Impaired Diabetic Foot Ulcer Healing and All-Cause Re-Hospitalization

BACKGROUND

Diabetic Foot Ulcers (DFUs) are a common and feared complication of type 1 and type 2 diabetes. People with DFUs often present a significant clinical complexity due to multimorbidity, frailty, polypharmacy, and disabling conditions. Frailty, defined using the accumulation of health deficits model, has shown to predict worsening health status, hospitalizations, and death in older persons. There are no clinical studies, to date, that have examined the prevalence and effect of frailty on DFUs outcomes. The aim of our study was to explore the impact of frailty on DFUs healing and re-hospitalization in a cohort of patients hospitalized with DFUs.

DESIGN

prospective cohort study.

SETTING AND PARTICIPANTS

The frailty status of 76 consecutive hospitalized patients with DFUs was assessed by using the Frailty Index (FI).

MEASUREMENTS

The primary outcome was the non-healing of the DFU. Secondary outcome was re-hospitalization events (for any cause) within 6 months from hospital discharge. Frailty was defined as FI>0.25.

RESULTS

Out of 76 patients (median age 65 years, range 31-84), 56 (74%) were frail. At six months, 81.5% of frail patients had non-healing of the DFU compared to 55% in non-frail patients (p=0.02). The rate of of re-hospitalization was also higher in frail compared to non-frail (90.3% vs 54%, respectively; p=0.01) patients. In multivariable analyses, frailty was significantly associated with a more than fivefold increased risk of DFU non-healing [odds ratio 5.54 (95% confidence interval 1.28-23.91), p=0.02]. Similarly, re-hospitalization was also significantly higher in frail patients compared to the non-frail ones.

CONCLUSIONS

In hospitalized patients with DFUs, frailty was highly prevalent. Frailty emerged as an independent risk factor for DFU non-healing and re-hospitalization events. Patients with DFUs require a comprehensive assessment of their frailty status which would enable personalization of their management and interventions.

Increasing Antibiotic Susceptibility: The Use of Cationic Gold Nanoparticles in Gram-Negative Bacterial Membrane Models

Antibiotic resistance will be one of the most prominent challenges to health-care systems in the coming decades, with the OECD predicting that up to 2.4 million deaths will be caused between 2015 and 2050 by drug-resistant bacterial infections in first-world countries alone, with infections costing health-care systems billions of dollars each year. Developing new methods to increase bacterial susceptibility toward drugs is an important step in treating resistant infections. Here, the synergistic effects of gold nanoparticles and the antibiotic drug colistin sulfate have been examined. A tethered lipid bilayer membrane was used to mimic a Gram-negative bacterial cell membrane. Exposing the membrane to gold nanoparticles prior to adding the antibiotic significantly increased the effect of the antibiotic on the membrane. Cationic gold nanoparticles could thus be used to enhance bacterial susceptibility to antibiotics, leading to a more potent treatment.

Smoking habits of UK military personnel on deployment: Exercise SAIF SAREEA 3

INTRODUCTION

Changes of environment brought about by deployments are often attributed to an increase in smoking of service personnel. Electronic cigarettes are recognised as being a viable aid to quitting smoking but are currently banned from sale in Oman and were therefore banned during exercise SAIF SAREEA 3 (SS3). This paper sought to establish whether smoking increased on this exercise and for what reasons. Also, if deployed smoking cessation services are likely to be used, if available.

METHODS

Questionnaires were distributed to deployed troops at various locations in theatre for data collection.

RESULTS

Smoking prevalence increased by 5.2% (29) in the deployed population by the end of the exercise. The largest increase was seen in those smoking 20 cigarettes a day or more, rising by 269.8% (73) with a mean increase of 9 cigarettes per day. During the exercise the number of personnel using electronic cigarettes decreased and individuals' rate of electronic cigarette use also decreased. Those who smoked less during the exercise did mainly through choice (56.8%). 50% (280) of all individuals who increased smoking habits during the exercise did so out of boredom.

CONCLUSIONS

During exercise SS3 the number of individuals who smoked and the quantity they smoked increased. The ban on electronic cigarettes in Oman and while on exercise potentially had an effect on the increased smoking habits. There is an argument to include smoking cessation material in medical modules to prevent ex-smokers from restarting, continue to aid those quitting and potentially lessen severity of increasing smoking habits while deployed.

Injuries during transition periods across the year in pre-professional and professional ballet and contemporary dancers: A systematic review and meta-analysis

OBJECTIVE

To consider the association of injuries with transition periods in the dance year, i.e., when dancers return at the start of the year, and when they transition from rehearsal to performance periods.

METHODS

Six electronic databases were searched to November 2019. All English language peer-reviewed studies, of any study design investigating ballet and contemporary pre-professional and professional dance populations were included. Only those studies reporting on the timing of injury were included.

RESULTS

Fifteen cohort and two case-series studies were included. A meta-analysis of seven studies revealed the rate of injuries to be significantly higher for the second and third months (1.52; 95% confidence interval [CI]:1.11-2.08; 1.26; 95%CI:1.07-1.48 respectively) after the return to dance. Two further studies report more injuries up to Week 13 of the year. One study showed an increase in injured dancers at three and four weeks after transition from rehearsals to a performance season. Four studies show an increase in injuries at performance times.

CONCLUSIONS

Meta-analyses of seven studies shows the second and third months after returning to dance have a significantly higher rate of injuries. More research is needed to quantify training loads in dance. Practitioners should be cognisant of the higher injury rates during periods of transition and consider modifying load, as it is a potential contributing factor.

Multifocal and multicentric breast cancer, is it time to think again?

Multifocal multicentric breast cancer has traditionally been considered a contraindication to breast conserving surgery because of concerns regarding locoregional control and risk of disease recurrence. However, the evidence supporting this practice is limited. Increasingly, many breast surgeons are advocating breast conservation in selected cases. This short narrative review summarises current evidence on the role of surgery in multifocal multicentric breast cancer and shows that when technically feasible the option of breast conservation is oncologically safe.

Identical and Nonidentical Twins: Risk and Factors Involved in Development of Islet Autoimmunity and Type 1 Diabetes

OBJECTIVE

There are variable reports of risk of concordance for progression to islet autoantibodies and type 1 diabetes in identical twins after one twin is diagnosed. We examined development of positive autoantibodies and type 1 diabetes and the effects of genetic factors and common environment on autoantibody positivity in identical twins, nonidentical twins, and full siblings.

RESEARCH DESIGN AND METHODS

Subjects from the TrialNet Pathway to Prevention Study (N = 48,026) were screened from 2004 to 2015 for islet autoantibodies (GAD antibody [GADA], insulinoma-associated antigen 2 [IA-2A], and autoantibodies against insulin [IAA]). Of these subjects, 17,226 (157 identical twins, 283 nonidentical twins, and 16,786 full siblings) were followed for autoantibody positivity or type 1 diabetes for a median of 2.1 years.

RESULTS

At screening, identical twins were more likely to have positive GADA, IA-2A, and IAA than nonidentical twins or full siblings (all P < 0.0001). Younger age, male sex, and genetic factors were significant factors for expression of IA-2A, IAA, one or more positive autoantibodies, and two or more positive autoantibodies (all P ≤ 0.03). Initially autoantibody-positive identical twins had a 69% risk of diabetes by 3 years compared with 1.5% for initially autoantibody-negative identical twins. In nonidentical twins, type 1 diabetes risk by 3 years was 72% for initially multiple autoantibody-positive, 13% for single autoantibody-positive, and 0% for initially autoantibody-negative nonidentical twins. Full siblings had a 3-year type 1 diabetes risk of 47% for multiple autoantibody-positive, 12% for single autoantibody-positive, and 0.5% for initially autoantibody-negative subjects.

CONCLUSIONS

Risk of type 1 diabetes at 3 years is high for initially multiple and single autoantibody-positive identical twins and multiple autoantibody-positive nonidentical twins. Genetic predisposition, age, and male sex are significant risk factors for development of positive autoantibodies in twins.

EYA4 is inactivated biallelically at a high frequency in sporadic lung cancer and is associated with familial lung cancer risk

In an effort to identify novel biallelically inactivated tumor suppressor genes (TSG) in sporadic invasive and pre-invasive non-small cell lung cancer (NSCLC) genomes, we applied a comprehensive integrated multi-‘omics approach to investigate patient matched, paired NSCLC tumor and non-malignant parenchymal tissues. By surveying lung tumor genomes for genes concomitantly inactivated within individual tumors by multiple mechanisms, and by the frequency of disruption in tumors across multiple cohorts, we have identified a putative lung cancer TSG, Eyes Absent 4 (EYA4). EYA4 is frequently and concomitantly deleted, hypermethylated and underexpressed in multiple independent lung tumor data sets, in both major NSCLC subtypes, and in the earliest stages of lung cancer. We find not only that decreased EYA4 expression is associated with poor survival in sporadic lung cancers, but EYA4 SNPs are associated with increased familial cancer risk, consistent with EYA4’s proximity to the previously reported lung cancer susceptibility locus on 6q. Functionally, we find that EYA4 displays TSG-like properties with a role in modulating apoptosis and DNA repair. Cross examination of EYA4 expression across multiple tumor types suggests a cell type-specific tumorigenic role for EYA4, consistent with a tumor suppressor function in cancers of epithelial origin. This work shows a clear role for EYA4 as a putative TSG in NSCLC.

Quality improvement framework for major amputation: are we getting it right?

INTRODUCTION

The quality improvement framework for major amputation was developed with the aim of improving outcomes and reducing the perioperartive mortality to less than 5% by 2015. The aim of the study was to assess our compliance with the framework guidelines and look for the reasons for non-compliance.

METHOD

All major amputations performed between 2008 and 2010 were included. The following data were collected: presence of infection ± tissue loss, status of arterial supply, revascularisation attempts, time to surgery, type of amputation, morbidity and mortality.

RESULTS

A total of 81 patients were included (42 BKAs, 39 AKAs). Ninety percentage had formal preoperative arterial investigations and 84% had an attempted revascularisation procedure. Patients who were transferred late from non-vascular units (n = 12) had a 30-day mortality of 50% whereas patients who presented directly to our unit had a 30-day mortality of 7.2%. The number of amputations has decreased over the last 3 years from 34 to 21 per year, coinciding with the doubling of crural revascularisation procedures performed (from 60 to 120 per year). Ten patients underwent a revision from BKA to AKA because of an inadequate profunda femoris artery (PFA), whereas all those with a healed BKA stump either had a good PFA or a named crural vessel.

CONCLUSION

The overall number of amputations is decreasing from year to year. By doubling our crural revascularisation procedures we are saving more limbs. Thirty-day mortality is higher than expected, particularly in patients who present late. Expeditious referral may potentially improve the mortality rate among this group of patients.

Abnormal gangliosides are localized in lipid rafts in Sanfilippo (MPS3a) mouse brain

Allogenic stem cell transplantation can reduce lysosomal storage of heparan sulfate-derived oligosaccharides by up to 27 % in Sanfilippo MPS3a brain, but does not reduce the abnormal storage of sialolactosylceramide (G(M3)) or improve neurological symptoms, suggesting that ganglioside storage is in a non-lysosomal compartment. To investigate this further we isolated the Triton X100-insoluble at 4 °C, lipid raft (LR) fraction from a sucrose-density gradient from cerebral hemispheres of a 7 month old mouse model of Sanfilippo MPS3a and age-matched control mouse brain. HPLC/MS/MS analysis revealed the expected enrichment of normal complex gangliosides, ceramides, galatosylceramides and sphingomyelin enrichment in this LR fraction. The abnormal HS-derived oligosaccharide storage material was in the Triton X100-soluble at 4 °C fractions (8-12),whereas both GM3 and sialo[GalNAc]lactosylceramide (GM2) were found exclusively in the LR fraction (fractions 3 and 4) and were >90 % C18:0 fatty acid, suggesting a neuronal origin. Further analysis also revealed a >threefold increase in the late-endosome marker bis (monoacylglycerol) phosphate (>70 % as C22:6/22:6-BMP) in non-LR fractions 8-12 whereas different forms of the proposed BMP precursor, phosphatidylglycerol (PG) were in both LR and non-LR fractions and were less elevated in MPS3a brain. Thus heparan sulfate-derived oligosaccharide storage is associated with abnormal lipid accumulation in both lysosomal (BMP) and non-lysosomal (GM3 and GM2) compartments.

Assessment of shoulder function using the coronal plane angle

Background:

Assessment of shoulder function is an essential part of clinical practice. Current scoring relies on multiple subjective and / or objective components. We present a single angular measurement, the coronal plane angle, which relates to the functional assessment of the shoulder.

Materials and Methods:

One hundred patients were prospectively enrolled and assessed using the Constant-Murley score and the Oxford shoulder questionnaire, and the coronal plane angle was measured for both symptomatic and asymptomatic shoulder.

Results:

Nine patients were excluded from the study: Four had apprehension and five were not able to get their hand to head. The mean coronal plane angle on the symptomatic side was +11.3° and the asymptomatic side −1.5° (P ≤ 0.01). Pearson's correlation of 0.9 and 0.84 was demonstrated for the Constant-Murley and Oxford shoulder scores, respectively, with the coronal plane angle.

Conclusion:

The coronal plane angle is a single objective assessment and provides a simple alternative to shoulder assessment for the majority of patients.

Biochemical profiling to predict disease severity in metachromatic leukodystrophy

Metachromatic leukodystrophy is a neurodegenerative disease that is characterized by a deficiency of arylsulfatase A, resulting in the accumulation of sulfatide and other lipids in the lysosomal network of affected cells. Accumulation of sulfatide in the nervous system leads to severe impairment of neurological function with a fatal outcome. Prognosis is often poor unless treatment is carried out before the onset of clinical symptoms. Pre-symptomatic detection of affected individuals may be possible with the introduction of newborn screening programs. The ability to accurately predict clinical phenotype and rate of disease progression in asymptomatic individuals will be essential to assist selection of the most appropriate treatment strategy. Biochemical profiling, incorporating the determination of residual enzyme protein/activity using immune-based assays, and metabolite profiling using electrospray ionization-tandem mass spectrometry, was performed on urine and cultured skin fibroblasts from a cohort of patients representing the clinical spectrum of metachromatic leukodystrophy and on unaffected controls. Residual enzyme protein/activity in fibroblasts was able to differentiate unaffected controls, arylsulfatase A pseudo-deficient individuals, pseudo-deficient compound heterozygotes and affected patients. Metachromatic leukodystrophy phenotypes were distinguished by quantification of sulfatide and other secondarily altered lipids in urine and skin fibroblasts; this enabled further differentiation of the late-infantile form of the disorder from the juvenile and adult forms. Prediction of the rate of disease progression for metachromatic leukodystrophy requires a combination of information on genotype, residual arylsulfatase A protein and activity and the measurement of sulfatide and other lipids in urine and cultured skin fibroblasts.

Glomus tumour following a total knee replacement: a case report

Pain following total knee replacement (TKR) is a common problem and cause of poor satisfaction amongst patients. We report on a glomus tumour causing pain on the anterolateral aspect of the knee, 2 years after an otherwise successful total knee replacement for osteoarthritis. The tumour was treated by excision biopsy under general anaesthesia and the diagnosis confirmed by histopathological examination. The removal of the tumour relieved the pain and the patient regained good function. We conclude that a thorough clinical assessment of a patient with a painful knee following TKR is essential to detect and treat coincidental painful pathology.

Impact of a real-time peer review audit on patient management in a radiation oncology department

In September 2006, the Royal Australian and New Zealand College of Radiologists (RANZCR) endorsed the modified Peer Review Audit Tool (PRAT). We aimed to assess the feasibility of using this tool in a busy radiation oncology department using an electronic medical record (EMR) system, identify areas of compliance and assess the impact of the audit process on patient management. Fortnightly random clinical audit was undertaken by using the revised RANZCR PRAT in the departments of radiation oncology at Liverpool and Macarthur Cancer Therapy Centres (LCTC and MCTC). Following audit of the EMR, treatment plans were audited by peer review. Data were collected prospectively from June 2007 to June 2008. Audits were carried out on 208 patients. Behaviour criteria were well documented in the EMR, but scanning of histology and medical imaging reports did not occur in up to a third of cases. With electronic prescriptions, treatment prescription errors were rare. In total, 8 (3.8%) out of 208 patients had a change to management recommended. Variability in interpretation of PRAT 'protocol/study' criteria was identified. We found that real-time audit is feasible and effective in detecting both issues with documentation in the EMR, and a small number of patients in whom a change to management is recommended. Recommendations have been made in order to continue to improve the audit process including documentation of any changes recommended and whether the recommended change occurred.

The significance of the choice of radiobiological (NTCP) models in treatment plan objective functions

A Clinician's discrimination between radiation therapy treatment plans is traditionally a subjective process, based on experience and existing protocols. A more objective and quantitative approach to distinguish between treatment plans is to use radiobiological or dosimetric objective functions, based on radiobiological or dosimetric models. The efficacy of models is not well understood, nor is the correlation of the rank of plans resulting from the use of models compared to the traditional subjective approach. One such radiobiological model is the Normal Tissue Complication Probability (NTCP). Dosimetric models or indicators are more accepted in clinical practice. In this study, three radiobiological models, Lyman NTCP, critical volume NTCP and relative seriality NTCP, and three dosimetric models, Mean Lung Dose (MLD) and the Lung volumes irradiated at 10Gy (V10) and 20Gy (V20), were used to rank a series of treatment plans using, harm to normal (Lung) tissue as the objective criterion. None of the models considered in this study showed consistent correlation with the Radiation Oncologists plan ranking. If radiobiological or dosimetric models are to be used in objective functions for lung treatments, based on this study it is recommended that the Lyman NTCP model be used because it will provide most consistency with traditional clinician ranking.

Hospitalisation and resource utilisation in patients with schizophrenia following initiation of risperidone long-acting therapy in the Veterans Affairs Healthcare System

OBJECTIVE

To examine hospitalisation rates and resource utilisation following initiation of risperidone long-acting therapy (RLAT) among US veterans with schizophrenia.

METHODS

Encounter data were analysed from the Ohio Veterans Affairs (VA) Healthcare System. Adult patients (schizophrenia or schizoaffective disorder) with ≥1 medical or hospital visits with a diagnosis code of 295.xx, continuous enrolment from January 2003 through January 2006, and ≥4 injections of RLAT were selected. Analyses compared psychiatric-related resource utilisation pre- and post-exposure to RLAT; each patient served as his/her own control. The pre-exposure and post-exposure periods defined were equal in duration (e.g., a 6-month post-exposure period was matched with a 6-month pre-exposure period). Descriptive and comparative analyses (paired t tests, McNemar's test) were performed.

RESULTS

Patients (n=106) were 51.9 years old (+/-10.2), male (93%), white (73%) and received on average 14 RLAT doses (+/-9.7; range, 4-47 injections) over 309 days (+/-196; range, 42-737 days). Most experienced a psychiatric-related hospitalisation prior to initiation; less than half experienced hospitalisation after initiation (75% vs. 42%; p<0.001). Relative to pre-initiation, fewer psychiatric-related hospitalisations (mean [SD] change, -0.8 [2.0]; p<0.001), shorter length of stay (-25 [63.6] days; p<0.001), fewer inpatient days/month (-3.1 [7.2] days) and one (2.8) additional outpatient visit/month (p<0.001) occurred post-initiation.

LIMITATIONS

The absence of a control group in this pre-/post comparison may have resulted in exposure to a regression to the mean effect. Also, this study evaluated only one cohort of patients in a VA healthcare setting.

CONCLUSIONS

VA patients with schizophrenia and schizoaffective disorder treated with RLAT experienced fewer hospitalisations and psychiatric-related inpatient days following RLAT initiation. Further studies utilising a control group and in non-VA populations are warranted.

Effect of intravenous contrast on treatment planning system dose calculations in the lung?

Intravenous contrast-enhanced computed tomography is utilised in radiotherapy lung treatment planning to improve the delineation of the tumour volume and nodal areas. In the resultant CT images, the electron density is increased within the vascular structures of the lung and the overall density in the lung volume may also be increased. As yet, it is unclear whether the change in density affects the accuracy of dose calculations based on this CT data. Two investigations were undertaken. Firstly, contrast-enhancement was simulated using an anthropomorphic phantom. In the second investigation, bulk density corrections were performed in an existing patient dataset. In both investigations, treatment plans were generated using both pre- and post-contrast datasets. The numbers of monitor units calculated in each of the plans were compared, as were the resulting isodose curves, dose volume histograms and physical mean lung doses. The numbers of monitor units calculated from the contrast- and non contrast-enhanced datasets agreed within 2%. The isodose curves and dose volume histograms showed very minor differences in size and shape. With the introduction of contrast agent, the physical mean lung doses calculated remained below the limit recommended for an acceptable plan. These results indicate that the introduction of contrast agent has a minimal dosimetric impact upon lung cancer treatment plans.

Can the Use of HIV-1 Derived Gene Transfer Vectors for Clinical Application be Justified?

Vectors derived from human immunodeficiency virus type 1 (HIV-1) are an attractive option for many gene therapy applications as they can transduce non-cycling cell populations, and can integrate their genome into the host cell chromosome. The rationale underlying the design of most retroviral vector systems is to segregate the viral cis sequences, which are required for transfer of the viral genome, from the trans sequences that encode viral proteins. This allows the efficient production of replication incompetent virus and has been successfully applied to the generation of HIV-1 vectors. Nonetheless, the possibility that recombination events in the vector production system can generate replication-competent virus, combined with the pathogenic nature of HIV-1, raises major bio-safety issues. Numerous HIV-1 vectors have now been reported, with each generation significantly improved in ways designed to reduce the risk of replication-competent virus being produced. However, progress in vector design needs to be complemented by the development of methods for the quantitation of the probability of replication competent virus being produced. Assaying individual events in the multi-step pathway that can lead to the production of replication-competent virus, rather than relying on the detection of replication-competent virus per se, will be important for quality control purposes. This review will specifically examine the approaches to HIV-1 vector design that have been postulated as increasing bio-safety, possible methods for evaluating bio-safety and whether these approaches are likely to be sufficient to overcome resistance to the use of HIV-1 for clinical application. In addition, we discuss the possible justifications for developing vectors from lentiviruses other than HIV-1.

Mass spectrometry in the study of lysosomal storage disorders

Lysosomal storage disorders represent a group of over 45 distinct genetic diseases, each one resulting from a deficiency of a particular lysosomal protein or, in a few cases, from non-lysosomal proteins that are involved in lysosomal biogenesis. A common biochemical feature of this group of disorders is the accumulation within lysosomes of undegraded or partially degraded substrates that are normally degraded within, and transported out of the lysosome. The particular substrates stored and the site(s) of storage vary with disease type and enzyme/protein deficiency. The nature of the substrate can be used to group the disorders into broad categories including the mucopolysaccharidoses, lipidoses, glycogenoses and oligosaccharidoses. These categories show many clinical similarities within groups as well as significant similarities between groups. For most lysosomal storage disorders the relationship between the stored substrates (type, amount and location) and the disease pathology is not well understood. The use of mass spectrometry and in particular tandem mass spectrometry provides a powerful tool for the investigation of stored substrates in this group of disorders. In this review we will describe the use of mass spectrometry for the analysis of stored substrates. We will discuss progress in the field, limitations of current methods, and summarise issues relating to the diagnosis and treatment of some of the more prevalent lysosomal storage disorders.

Rational development of a HIV-1 gene therapy vector

BACKGROUND

HIV-1 provides an attractive option as the basis for gene transfer vectors due to its ability to stably transduce non-cycling cell populations. In order to fully utilise the promise of HIV-1 as a vector it is important that the effects of viral cis sequence elements on vector function are carefully delineated.

METHODS

In this study we have systematically evaluated the effect of various cis elements from the HIV-1 YU-2 genome that have been implicated as either affecting vector performance, or HIV-1 replication, on the efficiency of vector production (titre and infectivity). As a measure of the relative safety of vectors their propensity to inadvertently transfer the gagpol gene to transduced cells was assessed.

RESULTS

Sequences that were found to increase vector titre were from the 5' end of the gag gene, from the 5' and 3' ends of the env gene, from immediately upstream of the polypurine tract, and the central polypurine tract. The substitution of the HIV-1 RRE with heterologous RNA transport elements, or the deletion of the RRE, resulted in greatly reduced vector titres. RNA analysis suggested that the role of the Rev/RRE system extends beyond simply acting as an RNA nuclear export signal. The relative safety of different vector designs was compared and an optimal construct selected.

CONCLUSIONS

Based on our results we have constructed a vector that is both more efficient, and has better safety characteristics, than the widely used pHR' HIV-1 vector construct.

On the confirmation of an effect of magnetic fields on the interictal firing rate of epileptic patients

The effect of magnetic fields on interictal firing rates was investigated in three epileptic patients with depth electrode implantation in the hippocampus for pre-surgical evaluation. The protocol consisted of 10 min test periods, during which magnetic fields were cycled for 1 min on and 1 min off, and intervening 5 min rest periods. Only one patient revealed a 95% significant increase in the 10 s after the fields were switched on compared with the background estimate from the 10s before the fields were applied. This patient was also the only patient to show significant increases in firing rates during field-on compared with field-off periods, and during magnetic field test periods compared with intervening rest periods. This patient had a right hippocampal seizure onset. All patients showed increased firing rates during the 10 min periods of magnetic field testing compared to the 5 min rest periods between tests. This result was significant for the group at the 99% level. Two patients with right temporal lobe onset showed greater activity in the right hippocampus than the left. All patients exhibited a progressive increase in firing rates in rest periods between tests.

Helper plasmids for production of HIV-1-derived vectors

Vectors derived from human immunodeficiency virus type 1 (HIV-1) appear an attractive option for many gene therapy applications. This is due to their ability to transduce noncycling cell populations and to integrate their genome into the host cell chromosome, resulting in the stable genetic modification of the transduced cell. These properties have permitted the direct in vivo transduction of several tissues, including the central nervous system, retina, and liver. However, the pathogenic nature of HIV-1 has raised considerable concerns about the safety of such vector systems. To help address these concerns, we have expressed each of the primary transcriptional units encoding trans functions relevant for vector production in individual plasmid constructs. The gag-pol gene sequence was codon-optimized for expression in mammalian cells resulting in high level Rev/Rev-response element (RRE)-independent expression. Codon optimization of gag-pol also reduces sequence homology with vectors containing gag gene sequences, which results in reduced transfer of biologically active gag-pol sequences to transduced cells. Furthermore, the vif reading frame overlapping the 3' end of the pol coding sequence is destroyed by codon optimization. We have also shown that the Gag and Gag-Pol polyproteins can be efficiently expressed from separate transcriptional units. This has enabled the removal of a cis-acting viral element, the gag-pol translational frameshift sequence, from the vector/packaging system and prevents detectable transfer of biologically active sequences equivalent to the gag-pol gene to transduced cells.

Prefrontal cortical sulcal widening associated with poor treatment response to clozapine

Increased sulcal widening in the prefrontal cortex of patients with schizophrenia may be associated with a poor treatment response to clozapine. To further evaluate this, we examined data from patients treated with clozapine in our center. Patients with the greatest degree of improvement (n=26) and those with no improvement (n=10) were compared. Computerized tomography (CT) scans were rated blindly on a visual scale of prefrontal sulcal widening. Patients with the greatest degree of functional improvement had significantly less prefrontal sulcal widening than those whose symptoms remained unchanged. There was no relationship between clozapine response and general sulcal widening. These data support the link between the superior therapeutic efficacy of clozapine and the integrity of the prefrontal cortex.