Cost-Effectiveness of Cardiovascular Magnetic Resonance for Rejection Surveillance After Cardiac Transplantation in the Australian Health Care System

BACKGROUND

Heart transplantation is an effective treatment for end-stage congestive heart failure, however, achieving the right balance of immunosuppression to maintain graft function while minimising adverse effects is challenging. Serial endomyocardial biopsies (EMBs) are currently the standard for rejection surveillance, despite being invasive. Replacing EMB-based surveillance with cardiac magnetic resonance (CMR)-based surveillance for acute cardiac allograft rejection has shown feasibility. This study aimed to assess the cost-effectiveness of CMR-based surveillance in the first year after heart transplantation.

METHOD

A prospective clinical trial was conducted with 40 orthotopic heart transplant (OHT) recipients. Participants were randomly allocated into two surveillance groups: EMB-based, and CMR-based. The trial included economic evaluations, comparing the frequency and cost of surveillance modalities in relation to quality-adjusted life years (QALYs) within the first year post-transplantation. Sensitivity analysis encompassed modelled data from observed EMB and CMR arms, integrating two hypothetical models of expedited CMR-based surveillance.

RESULTS

In the CMR cohort, 238 CMR scans and 15 EMBs were conducted, versus (vs) 235 EMBs in the EMB group. CMR surveillance yielded comparable rejection rates (CMR 74 vs EMB 94 events, p=0.10) and did not increase hospitalisation risk (CMR 32 vs EMB 46 events, p=0.031). It significantly reduced the necessity for invasive EMBs by 94%, lowered costs by an average of AUD$32,878.61, and enhanced cumulative QALY by 0.588 compared with EMB. Sensitivity analysis showed that increased surveillance with expedited CMR Models 1 and 2 were more cost-effective than EMB (all p<0.01), with CMR Model 1 achieving the greatest cost savings (AUD$34,091.12±AUD$23,271.86 less) and utility increase (+0.62±1.49 QALYs, p=0.011), signifying an optimal cost-utility ratio. Model 2 showed comparable utility to the base CMR model (p=0.900) while offering the benefit of heightened surveillance frequency during periods of elevated rejection risk.

CONCLUSIONS

CMR-based rejection surveillance in orthotopic heart transplant recipients provides a cost-effective alternative to EMB-based surveillance. Furthermore, it reduces the need for invasive procedures, without increased risk of rejection or hospitalisation for patients, and can be incorporated economically for expedited surveillance. These findings have important implications for improving patient care and optimising resource allocation in post-transplant management.

Echocardiographic Evaluation of Diastolic Function in Special Populations

Left ventricular (LV) diastolic dysfunction results from a combination of impaired relaxation, reduced restoring forces, and increased chamber stiffness. Noninvasive assessment of diastology uses a multiparametric approach involving surrogate markers of increased filling pressures, which include mitral inflow, septal and lateral annular velocities, tricuspid regurgitation velocity, and left atrial volume index. However, these parameters must be used cautiously. This is because the traditional algorithms for evaluating diastolic function and estimation of LV filling pressures (LVFPs), as recommended by the American Society of Echocardiography and European Association of Cardiovascular Imaging 2016 guidelines, do not apply to unique patients with underlying cardiomyopathies, significant valvular disease, conduction abnormalities, arrhythmias, LV assist devices, and heart transplants, which alter the relation between the conventional indexes of diastolic function and LVFP. The purpose of this review is to provide solutions for evaluating LVFP through illustrative examples of these special populations, incorporating supplemental Doppler indexes, such as isovolumic relaxation time, mitral deceleration time, and pulmonary venous flow analysis, as needed to formulate a more comprehensive approach.

Echo Doppler Parameters of Diastolic Function

PURPOSE OF REVIEW

The purpose of this review is to highlight the echo Doppler parameters that form the cornerstone for the evaluation of diastolic function as per the guideline documents of the American Society of Echocardiography (ASE) and the European Association of Cardiovascular Imaging (EACVI). In addition, the individual Doppler-based parameters will be explored, with commentary on the rationale behind their use and the multi-parametric approach to the assessment of diastolic dysfunction (DD) using echocardiography.

RECENT FINDINGS

Previous guidelines for assessment of diastolic function are complex with modest diagnostic performance and significant inter-observer variability. The most recent guidelines have made the evaluation of DD more streamlined with excellent correlation with invasive measures of LV filling pressures. This is a review of the echo-derived Doppler parameters that are integral in the diagnosis and gradation of DD. A brief description of the physiological principles that govern changes in echocardiographic parameters during normal and abnormal diastolic function is also discussed for the appropriate diagnosis of DD using non-invasive Doppler echocardiography techniques.

Cardiovascular Magnetic Resonance for Rejection Surveillance After Cardiac Transplantation

BACKGROUND

Endomyocardial biopsy (EMB) is the gold standard method for surveillance of acute cardiac allograft rejection (ACAR) despite its invasive nature. Cardiovascular magnetic resonance (CMR)-based myocardial tissue characterization allows detection of myocarditis. The feasibility of CMR-based surveillance for ACAR-induced myocarditis in the first year after heart transplantation is currently undescribed.

METHODS

CMR-based multiparametric mapping was initially assessed in a prospective cross-sectional fashion to establish agreement between CMR- and EMB-based ACAR and to determine CMR cutoff values between rejection grades. A prospective randomized noninferiority pilot study was then undertaken in adult orthotopic heart transplant recipients who were randomized at 4 weeks after orthotopic heart transplantation to either CMR- or EMB-based rejection surveillance. Clinical end points were assessed at 52 weeks.

RESULTS

Four hundred one CMR studies and 354 EMB procedures were performed in 106 participants. Forty heart transplant recipients were randomized. CMR-based multiparametric assessment was highly reproducible and reliable at detecting ACAR (area under the curve, 0.92; sensitivity, 93%; specificity, 92%; negative predictive value, 99%) with greater specificity and negative predictive value than either T1 or T2 parametric CMR mapping alone. High-grade rejection occurred in similar numbers of patients in each randomized group (CMR, n=7; EMB, n=8; P=0.74). Despite similarities in immunosuppression requirements, kidney function, and mortality between groups, the rates of hospitalization (9 of 20 [45%] versus 18 of 20 [90%]; odds ratio, 0.091; P=0.006) and infection (7 of 20 [35%] versus 14 of 20 [70%]; odds ratio, 0.192; P=0,019) were lower in the CMR group. On 15 occasions (6%), patients who were randomized to the CMR arm underwent EMB for clarification or logistic reasons, representing a 94% reduction in the requirement for EMB-based surveillance.

CONCLUSIONS

A noninvasive CMR-based surveillance strategy for ACAR in the first year after orthotopic heart transplantation is feasible compared with EMB-based surveillance.

REGISTRATION

HREC/13/SVH/66 and HREC/17/SVH/80.

AUSTRALIAN NEW ZEALAND CLINICAL TRIALS REGISTRY

ACTRN12618000672257.

Emerging Therapies for Recurrent Pericarditis: Interleukin-1 inhibitors

Recurrent pericarditis (RP) is a complex inflammatory disorder associated with adverse outcomes and poor quality of life. After the first episode of acute pericarditis, a non‐negligible group of patients will fail to achieve complete remission despite treatment and will be challenged by side effects from the chronic use of medications like corticosteroids. The cause of RP remains unknown in the majority of cases, mainly due to a gap in knowledge of its complex pathophysiology. Over the past 2 decades, the interleukin‐1 (IL‐1) pathway has been uncovered as a key element in the inflammatory cascade, allowing the development of pharmacological targets known as IL‐1 inhibitors. This group of medications has emerged as a treatment option for patients with RP colchicine‐resistance and steroid dependents. Currently, anakinra and rilonacept, have demonstrated beneficial impact in clinical outcomes with a reasonable safety profile in randomized clinical trials. There is still paucity of data regarding the use of canakinumab in the treatment of patients with RP. Although further studies are needed to refine therapeutic protocols and taper of concomitant therapies, IL‐1 inhibitors, continue to consolidate as part of the pharmacological armamentarium to manage this complex condition with potential use as monotherapy. The aim of this review is to highlight the role of IL‐1 pathway in RP and discuss the efficacy, safety, and clinical applicability of IL‐1 inhibitors in the treatment of RP based on current evidence.

The Role of Rilonacept in Recurrent Pericarditis

Recurrent pericarditis is associated with significant morbidity and adverse impact on quality of life. Contemporary studies have emphasized the key role of autoinflammatory pathways in its pathophysiology, mainly through the activation of inflammasomes and the production of interleukin (IL)-1α and IL-1β. The IL-1 pathway has emerged as a promising target for the treatment of these patients. A novel IL-1 inhibitor, rilonacept, functions as an IL-1 trap binding to the circulating IL-1α and IL-1β mitigating their inflammatory response. Recently, the RHAPSODY phase III clinical trial evaluated the use of rilonacept in patients with recurrent pericarditis, who were refractory to colchicine, or steroid-dependent. Rilonacept significantly reduced symptoms, inflammatory markers and recurrent episodes, and increased successful withdrawal of steroids. The safety profile of the medication is favourable and well tolerated by patients, with local injection site reaction being the most common side effect described. These results have shifted the paradigm of the understanding of the disease and promise to become part of the armamentarium of medications for the standard of care of these patients, with potential use as monotherapy. The changing landscape of therapeutics and pathophysiology warrants increased recognition and understanding from the international cardiology community about this novel drug and its implication in managing these complex patients.The objective of this review is to describe the bio-action of rilonacept in the treatment of recurrent pericarditis.

Initial assessment of framework for delivery of elective orthopaedic surgery in the United Kingdom following the COVID-19 pandemic

Purpose

In light of the COVID-19 pandemic, a framework for safe provision of elective orthopaedic surgery must be developed in order to restore and maintain activity. The aim of this study was to explore patient attitudes to surgery and theatre efficiency as a result of the COVID-19 pandemic and assess a potential framework for the delivery of such services.

Methods

Prospectively collected data on theatre timings and procedures completed per session used to assess theatre efficiency comparing June 2019 to June 2020. Information on patient compliance with 14-day household isolation and attitudes to surgery were collected prospectively over a seven-week period using a questionnaire. Follow-up data were collected via telephone consultation a minimum of two weeks after discharge.

Results

Significant reduction in the number of points per session (p = 0.02) with a mean of 3.19 in 2019 and 2.42 in 2020. Only 18 of 31 patients were compliant with pre-operative isolation with individual failures accounting for four of 13 and failures by household members accounting for nine. Impact of COVID-19 and precautions on patient anxiety was mixed. No patients required symptomatic COVID-19 swab post-operatively.

Conclusion

With the restrictions of COVID-19, there are significant problems with theatre efficiency, in effect losing an operation a list. Furthermore, compliance with pre-operative isolation was poor but to the best of our knowledge no patients became unwell from COVID-19 post-operatively. Additional strategies will be required to reinstate an effective elective orthopaedic service, especially as the nation heads into another wave.

Everolimus for the Prevention of Calcineurin-Inhibitor-Induced Left Ventricular Hypertrophy After Heart Transplantation (RADTAC Study)

OBJECTIVES

This study aimed to determine the safety and efficacy of combined low-dose everolimus and low-dose tacrolimus compared with standard-dose tacrolimus in attenuating left ventricular hypertrophy (LVH) after orthotopic heart transplantation (OHT).

BACKGROUND

Calcineurin inhibitors (CNIs) such as tactrolimus are important in preventing cardiac allograft rejection and reducing mortality after OHT. However CNIs are causatively linked to the development of LVH, and are associated with nephrotoxicity and vasculopathy. CNI-sparing agents such as everolimus have been hypothesized to inhibit adverse effects of CNIs.

METHODS

In this prospective, randomized, open-label study, OHT recipients were randomized at 12 weeks after OHT to a combination of low-dose everolimus and tacrolimus (the RADTAC group) or standard-dose tacrolimus (the TAC group), with both groups coadministered mycophenolate and prednisolone. The primary endpoint was LVH indexed as the change in left ventricular mass (ΔLVM) by cardiovascular magnetic resonance (CMR) imaging from 12 to 52 weeks. Secondary endpoints included CMR-based myocardial performance, T1 fibrosis mapping, blood pressure, and renal function. Safety endpoints included episodes of allograft rejection and infection.

RESULTS

Forty stable OHT recipients were randomized. Recipients in the RADTAC group had significantly lower tacrolimus levels compared with the TAC group (6.5 ± 3.5 μg/l vs. 8.6 ± 2.8 μg/l; p = 0.02). The mean everolimus level in the RADTAC group was 4.2 ± 1.7 μg/l. A significant reduction in LVM was observed in the RADTAC group compared with an increase in LVM in the TAC group (ΔLVM = -13.0 ± 16.8 g vs. 2.1 ± 8.4 g; p < 0.001). Significant differences were also noted in secondary endpoints measuring function and fibrosis (Δ circumferential strain = -2.9 ± 2.8 vs. 2.1 ± 2.3; p < 0.001; ΔT1 mapping values = -32.7 ± 51.3 ms vs. 26.3 ± 90.4 ms; p = 0.003). No significant differences were observed in blood pressure (Δ mean arterial pressure = 4.2 ± 18.8 mm Hg vs. 2.8 ± 13.8 mm Hg; p = 0.77), renal function (Δ creatinine = 3.1 ± 19.9 μmol/l vs. 9 ± 21.8 μmol/l; p = 0.31), frequency of rejection episodes (p = 0.69), or frequency of infections (p = 0.67) between groups.

CONCLUSIONS

The combination of low-dose everolimus and tacrolimus compared with standard-dose tacrolimus safely attenuates LVH in the first year after cardiac transplantation with an observed reduction in CMR-measured fibrosis and an improvement in myocardial strain.

Combustion Method for Determination of Crude Protein in Meat and Meat Products: Collaborative Study

Twelve laboratories participated in a collaborative study to compare a combustion method with the AOAC mercury catalyst Kjeldahl method (928.08) for the determination of crude protein in meat and meat products. Three different combustion instruments were used; consequently, the combustion method for this study is written in generic terms describing the principle, the apparatus specifications, and the performance requirements needed. Fifteen sample pairs were used for the study; each pair consisted of the same commercial meat product from each of 2 different manufacturers. Protein content of all samples ranged from about 10 to 20%. In addition, nicotinic acid and lysine monohydrochloride were used as standards to assess combustion equipment performance. All laboratories and all instruments performed the combustion method satisfactorily on the basis of results for the standards. For the meat samples, repeatability standard deviations (sr) ranged from 0.11 to 0.40 for the Kjeldahl method and from 0.12 to 0.41 for the combustion method; the repeatability relative standard deviations (RSDr) ranged from 0.82 to 2.41% and from 0.60 to 2.23% for the Kjeldahl and combustion methods, respectively. Reproducibility standard deviations (SR) ranged from 0.20 to 0.49 for the Kjeldahl method and from 0.18 to 0.46 for the combustion method, whereas the reproducibility relative standard deviations (RSDR) ranged from 1.59 to 2.84% for the Kjeldahl method and from 1.32 to 3.35% for the combustion method. Overall grand means were 15.59% protein for the Kjeldahl method and 15.75% protein for the combustion method. The combustion method was adopted first action by AOAC International.

A1 The role of virus-antibody co-evolution in the development of a V3-glycan-directed HIV-1 broadly neutralizing antibody lineage

Broadly neutralizing antibodies (bNAbs) are essential for a preventative HIV-1 vaccine but have not been elicited through vaccination. bNAbs develop in 20–30 per cent of HIV-1 infections and often target the V3-glycan epitope of the HIV envelope protein (Env). In these individuals, virus-antibody co-evolution is thought to drive the maturation of antibody lineages to neutralization breadth. We used deep sequencing of env genes and antibody transcripts from fourteen time points spanning the first 3 years of infection to characterize the virus-antibody co-evolution in donor CAP255 who developed V3-glycan-specific bNAbs. Sequencing and cloning of env genes, followed by neutralization assays, were used to identify Env mutations associated with neutralization escape from two bNAbs (CAP255.G3 and CAP255.C5) isolated at 149 weeks post-infection (wpi). Sequencing data indicated that CAP255 was co-infected by three related viral variants, all of which had an intact N332 glycan, which persisted in > 90 per cent of later viruses. A recombinant V3-region became fixed from 8 wpi, conferring slight neutralization resistance to CAP255.G3/C5 and other V3-glycan bNAbs. Later, T415R/K substitutions in V4 emerged by 51 wpi and were associated with complete viral escape from CAP255.G3/C5, though not from the polyclonal plasma response. All 93-week and later Envs were resistant to CAP255.G3/C5 and V3-glycan bNAb PGT135. Viral escape by 51 wpi suggested that the CAP255 bNAbs arose earlier, driving escape, but persisted to 149 weeks. This was supported by preliminary deep sequencing of the antibody repertoire that indicated bNAb lineage members were already present in the plasma at 39 wpi. Escape from V3-glycan bNAbs via T415R/K mutations have not previously been shown, suggesting a novel mode of recognition within the V3-glycan supersite. Further work will focus on identifying the bNAb-initiating Env and intermediate bNAb lineage members that were capable of engaging contemporaneous Env neutralization escape mutants. Characterization of Envs that engaged bNAb precursors, as well as those that selected for broader members of the bNAb lineage, will inform the design of immunogens capable of eliciting V3-glycan bNAbs in a novel HIV-1 vaccine regimen.

Isolated myocardial relapse of Philadelphia-positive acute lymphoblastic leukaemia causing myocarditis: a case report

Background

Relapse of acute lymphoblastic leukaemia (ALL) causes significant morbidity. Extramedullary relapse is seldom isolated to one site and almost always coexists with extensive marrow disease. Leukaemic infiltration of the myocardium is a well described entity, evident in up to 44% of patients at post-mortem examination; however, ante-mortem diagnosis remains difficult and rare. As a result, myocardial involvement in the absence of any other foci of relapse has only seldom been reported.

Case summary

Here, we present an unusual case of isolated gross intracardiac relapse of ALL in a patient presenting with chest pain and fevers. Both cardiac magnetic resonance imaging and endomyocardial biopsy were utilized in the diagnosis and identified leukaemic infiltrate in the absence of peripheral lymphoblasts.

Discussion

Despite evidence supporting a positive correlation between peripheral lymphocyte count and myocardial infiltration, our case highlights the rare and hypothesis-driving occurrence of myocardial infiltration with a complete absence of a peripheral lymphoblastosis. The report highlights the utility of modern histopathological and imaging modalities in the diagnosis of isolated myocardial relapse of ALL and provides insight into the aetiologies driving this process.

Angioplasty versus stenting for infrapopliteal arterial lesions in chronic limb-threatening ischaemia

BACKGROUND

Chronic limb-threatening ischaemia (CLTI) is a manifestation of peripheral arterial disease (PAD) that includes chronic ischaemic rest pain or ischaemic skin lesions, ulcers, or gangrene for longer than two weeks. The severity of the disease depends on the extent of arterial stenosis and the availability of collateral circulation. Treatment for CLTI aims to relieve ischaemic pain, heal ischaemic ulcers, prevent limb loss, improve quality of life, and prolong survival. CLTI due to occlusive disease in the infrapopliteal arterial circulation (below-knee circulation) can be treated via an endovascular technique by a balloon opening the narrowed vessel, so called angioplasty, with or without the additional deployment of a scaffold made of metal alloy or other material, so called stenting. Endovascular interventions in the infrapopliteal vasculature may improve symptoms in patients with CLTI by re-establishing in-line blood flow to the foot. Controversy remains as to whether a balloon should be used alone to open the vessel, or whether a stent should also be deployed.

OBJECTIVES

To determine the efficacy and safety of percutaneous transluminal angioplasty (PTA) alone versus PTA with stenting of infrapopliteal arterial lesions (anterior tibial artery, posterior tibial artery, fibular artery (formerly known as peroneal artery), and common tibioperoneal trunk) for patients with chronic limb-threatening ischaemia (CLTI).

SEARCH METHODS

The Cochrane Vascular Information Specialist searched the Cochrane Vascular Specialised Register, CENTRAL, MEDLINE, Embase, CINAHL, and AMED databases, as well as World Health Organization International Clinical Trials Registry Platform and ClinicalTrials.gov trials registers to 25 June 2018. We applied no language restrictions.

SELECTION CRITERIA

We planned to include randomised or quasi-randomised controlled trials comparing PTA versus PTA with a stent and including patients aged 18 years or over with CLTI. We defined CLTI as Fontaine stage III (ischaemic rest pain) and IV (ischaemic ulcers or gangrene) or consistent with Rutherford category 4 (ischaemic rest pain), 5 (minor tissue loss), and 6 (major tissue loss), with stenotic (> 50% luminal loss) or occluded infrapopliteal artery, including tibiofibular trunk, anterior tibial artery, posterior tibial artery, and fibular artery. We included all types of stents irrespective of design (e.g. bare-metal, drug-eluting, bio-absorbable).

DATA COLLECTION AND ANALYSIS

Two review authors (CC-TH and GNCK) independently selected suitable trials, assessed trial quality, and extracted data. An additional third review author (MLvD) assessed trial quality and, when necessary, acted as arbiter for study selection and data extraction. Outcomes included technical success of the procedure, procedural complications, patency, major amputation, and mortality. We assessed the quality of evidence using the GRADE approach.

MAIN RESULTS

We included in the review seven trials with 542 participants. One trial randomised limbs to undergo PTA alone or PTA with stent placement, and the remaining studies randomised participants. Five trials with 476 participants show that the technical success rate was greater in the stent group than in the angioplasty group (odds ratio (OR) 3.00, 95% confidence interval (CI) 1.14 to 7.93; 476 lesions; 5 studies; I² = 23%). Meta-analysis of three eligible trials with 456 participants did not show a clear difference in short-term (within six months) patency between infrapopliteal arterial lesions treated with PTA and those treated with PTA and stenting (OR 0.88, 95% CI 0.37 to 2.11; 456 lesions; 3 studies; I² = 77%). Results also did not show clear differences between treatment groups in procedure complication rate (OR 0.87, 95% CI 0.01 to 53.60; 360 participants; 5 studies; I² = 85%), rate of major amputations at 12 months (OR 1.34, 95% CI 0.56 to 3.22; 306 participants; 4 studies; I² = 0%), and rate of mortality at 12 months (OR 0.71, 95% CI 0.43 to 1.17; 497 participants; 6 studies; I² = 0%). Heterogeneity between studies was high for the outcomes procedure complications and primary patency. The overall methodological quality of the trials included in this review was moderate due to selection and performance bias. Studies used different regimens for pretreatment and post-treatment antiplatelet/anticoagulant medication. We downgraded the certainty of the overall evidence for all outcomes by one level to moderate due to inconsistency of results across studies and large confidence intervals (small numbers of trials and participants).

AUTHORS' CONCLUSIONS

Trials show that the immediate technical success rate of restoring luminal patency is higher in the stent group but reveal no clear differences in short-term patency at six months between infrapopliteal arterial lesions treated with PTA with stenting versus those treated with PTA without stenting. We ascertained no clear differences between groups in periprocedural complications, major amputation, and mortality. However, use of different regimens for pretreatment and post-treatment antiplatelet/anticoagulant medication and the duration of its use within and between trials may have influenced the outcomes. Limited currently available data suggest that high-quality evidence is insufficient to show that PTA with stent insertion is superior to use of standard PTA alone without stenting for treatment of infrapopliteal arterial lesions. Further studies should standardise the use of antiplatelets/anticoagulants before and after the intervention to improve the comparability of the two treatments.

Life-Saving Combined Heart-Kidney Transplantation in a Previous Sequential Heart and Kidney Transplant Recipient

Purpose

Solid organ re-transplantation in the context of allograft failure is a challenging clinical and ethical problem. Ideally, solid organ re-transplantation after initial allograft failure should be performed in all recipients, but this is often not clinically or logistically feasible.

Methods

This report details what we believe is the first combined heart–kidney transplant in a recipient of a previous sequential heart and kidney transplant.

Results

Eight years after a combined heart and kidney transplant after initially receiving a sequential heart and kidney transplant, a 31-year-old man is doing extremely well, with no rejection episodes or significant complications after transplantation.

Summary

This case confirms that combined heart and kidney transplantation is a viable option for tackling the complex issue of graft failure in recipients of previous cardiac and renal grafts.

LEARNING POINTS

Effect of Lateral Column Lengthening Calcaneal Osteotomy on Radiographic Measurements of Foot Alignment

Category:

Hindfoot

Introduction/Purpose:

Lateral column lengthening (LCL) with calcaneal osteotomy has been increasingly used for reconstruction in flexible flat foot reconstruction. The aims of this study were to 1) evaluate the effects of variably sized LCL blocks on the restoration of alignment in an acute flat foot cadaveric model; 2) create a computer algorithm to more objectively measure foot alignment; and 3) develop an acute flat foot model that does not require cyclic loading for creating a type IIB flat foot. Determining if overcorrection with lateral column lengthening can occur would provide guidance surgeons to avoid lateral column overload. A computer guided measurement program could make studies more comparable. An acute flat foot model would clarify the ligament deficiencies necessary to create a type IIB flat foot.

Methods:

A type IIB flat foot model was used in which the medial and medial-plantar fibers of the calcaneonavicular (CN), the interosseous talo-calcaneal (ITCL) and the cervical (CL) ligaments were transected. Metallic markers were placed in the PF origin. 3D weightbearing CT scans were obtained with the specimens in a custom jig that permitted loading with 100 lbs. (445 N). The jig allowed full pronation under load. Scans were obtained: intact, flat, and with 6, 8 and 10 mm LCL blocks. Simulated AP and lateral radiographs were created using a custom MATLAB program. A custom ImageJ plugin was created which guided measurement of Meary’s angle, naviculo-cuneiform overlap, AP talo-first metatarsal angle, and a novel plantar fascia (PF) distance and PF angle. The program automatically calculated midpoints and perpendicular lines from guided user input. Four observers performed all measurements in blinded and randomized fashion on two occasions greater than 12 weeks apart.

Results:

The ligament sectioning model reliably produced a type IIB flat foot as noted by talo-navicular sag, increased talar head uncovering (forefoot abduction) and divergence of the talus and calcaneus as seen on the AP weightbearing view (Figure 1). Cyclic loading was not required in any specimens and the remaining medial column ligaments were not sectioned. Intraobserver and interobserver comparisons indicated naviculo-cuneiform overlap and plantar fascia distance had excellent interobserver agreement and Meary’s and plantar fascia angle had good interobserver agreement (Figure 1). Lateral column lengthening trended toward overcorrection at 10 mm suggesting a possible threshold for over-correction.

Conclusion:

The trend toward overcorrection with 10 mm LCL may indicate a threshold for lateral column overload. Computer guided measurement may improve consistency when comparing studies. The PF measurements are not possible in vivo. The use of a heel centering ring might be a surrogate for the implanted metallic beads. The CL sectioning was essential for creating type IIB flat foot without cyclic loading. The CL has been noted to be a main subtalar stabilizer, but has not entered into mainstream discussions regarding flat foot. Changes that occurred with cyclic loading performed in other flat foot studies have not been defined.

Transcatheter Aortic Valve Replacement for Native Aortic Valve Regurgitation

Transcatheter aortic valve replacement with either the balloon-expandable Edwards SAPIEN XT valve, or the self-expandable CoreValve prosthesis has become the established therapeutic modality for severe aortic valve stenosis in patients who are not deemed suitable for surgical intervention due to excessively high operative risk. Native aortic valve regurgitation, defined as primary aortic incompetence not associated with aortic stenosis or failed valve replacement, on the other hand, is still considered a relative contraindication for transcatheter aortic valve therapies, because of the absence of annular or leaflet calcification required for secure anchoring of the transcatheter heart valve. In addition, severe aortic regurgitation often coexists with aortic root or ascending aorta dilatation, the treatment of which mandates operative intervention. For these reasons, transcatheter aortic valve replacement has been only sporadically used to treat pure aortic incompetence, typically on a compassionate basis and in surgically inoperable patients. More recently, however, transcatheter aortic valve replacement for native aortic valve regurgitation has been trialled with newer-generation heart valves, with encouraging results, and new ancillary devices have emerged that are designed to stabilize the annulus-root complex. In this paper we review the clinical context, technical characteristics and outcomes associated with transcatheter treatment of native aortic valve regurgitation.

Comparison of two nested PCR methods for the detection of human malaria

Battling malaria will be a persistent struggle without the proper means to diagnose the parasitic infection. However, the inherent limitations of microscopy, the conventional method of diagnosing malaria, affect the accuracy of diagnosis. The present study aimed to compare the accuracy of two different set of primers targeting the small subunit ribosomal RNA (ssRNA) and the dihydrofolate reductase-thymidylate synthase linker region (dhfr-ts) in detecting species specific malaria infections by nested PCR. The sensitivity and specificity of nested PCR assay using the two primers were calculated with reference to microscopy as the 'gold standard'. The results show that 18S rRNA primers had 91.9% sensitivity and 100% specificity in detecting human Plasmodium species as opposed to dhfr-ts primers which had 51.4% sensitivity and 100% specificity. The higher sensitivity of 18S rRNA primers suggests that it may be a better diagnostic tool for detecting human malaria.

A behavioral weight-loss intervention for persons with serious mental illness in psychiatric rehabilitation centers

Objective

Overweight and obesity are epidemic in populations with serious mental illnesses. We developed and pilot tested a behavioral weight loss intervention appropriately tailored for persons with serious mental disorders.

Methods

We conducted a single arm pilot study in two psychiatric rehabilitation day programs in Maryland and enrolled 63 overweight or obese adults. The six-month intervention provided group and individual weight management and group physical activity classes. The primary outcome was weight change from baseline to 6 months.

Results

Sixty-four percent of those potentially eligible at the centers enrolled. The mean age was 43.7 years; 56% were women, 49% were white and over half had a schizophrenia or schizoaffective disorder. One third had hypertension and one fifth had diabetes. Fifty-two (82%) completed the study; others were discharged from psychiatric centers before study completion. Average attendance across all weight management sessions was 70% (87% on days participants attended the center) and 59% for physical activity classes (74% on days participants attended the center). From a baseline mean of 210.9 lbs (SD 43.9), average weight loss for 52 participants was 4.5 pounds (SD 12.8) (p<0.014). On average, participants lost 1.9% of body weight. Mean waist circumference change was 3.1 cm (SD 5.6). Participants on average increased the distance on the six minute walk test by eight percent.

Conclusion

This pilot documents the feasibility and preliminary efficacy of a behavioral weight loss intervention in adults with serious mental illness who were attendees at psychiatric rehabilitation centers. The results may have implications for developing weight loss interventions in other institutional settings such as schools or nursing homes.

The 1.6Å X-ray Structure of the Unusual c-type Cytochrome, Cytochrome cL, from the Methylotrophic Bacterium Methylobacterium extorquens

The structure of cytochrome cL from Methylobacterium extorquens has been determined by X-ray crystallography to a resolution of 1.6 A. This unusually large, acidic cytochrome is the physiological electron acceptor for the quinoprotein methanol dehydrogenase in the periplasm of methylotrophic bacteria. Its amino acid sequence is completely different from that of other cytochromes but its X-ray structure reveals a core that is typical of class I cytochromes c, having alpha-helices folded into a compact structure enclosing the single haem c prosthetic group and leaving one edge of the haem exposed. The haem is bound through thioether bonds to Cys65 and Cys68, and the fifth ligand to the haem iron is provided by His69. Remarkably, the sixth ligand is provided by His112, and not by Met109, which had been shown to be the sixth ligand in solution. Cytochrome cL is unusual in having a disulphide bridge that tethers the long C-terminal extension to the body of the structure. The crystal structure reveals that, close to the inner haem propionate, there is tightly bound calcium ion that is likely to be involved in stabilization of the redox potential, and that may be important in the flow of electrons from reduced pyrroloquinoline quinone in methanol dehydrogenase to the haem of cytochrome cL. As predicted, both haem propionates are exposed to solvent, accounting for the unusual influence of pH on the redox potential of this cytochrome.

Biochemistry: role of PQQ as a mammalian enzyme cofactor?

The announcement by Kasahara and Kato of a new redox-cofactor vitamin for mammals, pyrroloquinoline quinone (PQQ), was based on their claim that an enzyme, predicted to be involved in mouse lysine metabolism, is a PQQ-dependent dehydrogenase. However, this claim was dependent on a sequence analysis using databases that inappropriately label beta-propeller sequences as PQQ-binding motifs. What the evidence actually suggests is that the enzyme is an interesting novel protein that has a seven-bladed beta-propeller structure, but there is nothing to indicate that it is a PQQ-dependent dehydrogenase.

The atomic resolution structure of methanol dehydrogenase fromMethylobacterium extorquens

The crystal structure of methanol dehydrogenase (MDH) from Methylobacterium extorquens has been refined without stereochemical restraints at a resolution of 1.2 A. The high-resolution data have defined the conformation of the tricyclic pyrroloquinoline quinone (PQQ) cofactor ring as entirely planar. The detailed definition of the active-site geometry has shown many features that are similar to the quinohaemo-protein alcohol dehydrogenases from Comamonas testosteroni and Pseudomonas putida, both of which possess MDH-like and cytochrome c-like domains. Conserved features between the two types of PQQ-containing enzyme suggest a common pathway for electron transfer between MDH and its physiological electron acceptor cytochrome cL. A pathway for proton transfer from the active site to the bulk solvent is also suggested.

Clinical effects of air filters in homes of asthmatic adults sensitized and exposed to pet allergens

BACKGROUND

Despite medical advice, many pet-allergic asthma sufferers refuse to remove the pet to which they are sensitized from their home.

OBJECTIVE

We aimed to assess the clinical effects of air cleaners in the homes of adult asthma patients sensitized and exposed to cats and/or dogs.

METHODS

We performed a randomized, parallel-group study of 30 asthmatic adults sensitized to and sharing a home with cats or dogs. The effects of placing air cleaners in the living room and bedroom for 12 months and using high efficiency particulate air filter vacuum cleaners (active group) were compared with using these vacuum cleaners alone (control group). Measures of airway responsiveness, treatment requirement, lung function, peak flow, reservoir and airborne allergen were recorded before, during and after the interventions. A beneficial clinical response was assessed in terms of a 'combined asthma outcome'. This was defined as a two or more doubling dose improvement in bronchial hyper-reactivity to histamine and/or a reduction in treatment requirement of at least one step change on the British Thoracic Society guidelines for asthma treatment.

RESULTS

A beneficial clinical response was observed in 10/15 subjects in the active group compared with 3/15 in the control group after 12 months intervention (P = 0.01). No significant differences between the active and control groups were detected for changes in measures of lung function, reservoir pet allergen and airborne pet allergen during the study.

CONCLUSION

Whilst the study design has not allowed complete exclusion of a placebo effect, we believe that this pragmatic study of adult asthmatic patients sensitized and exposed to pets resulted in a small, but significant improvement in combined asthma outcome.

Overexpression of eIF4E in Saccharomyces cerevisiae causes slow growth and decreased alpha-factor response through alterations in CLN3 expression

The association of G(1) cyclins and Cdc28/cyclin-dependent protein kinase catalyzes the cell cycle entry (Start) in budding yeast. Activation of Start is presumed to be triggered by a post-transcriptional increase in Cln3 during early G(1). Cells arrested by mating pheromone show a loss of cyclin-dependent protein kinase activity caused by transcriptional shutoff of cyclins and/or inhibition by Far1. We report that overexpression of eIF4E (Cdc33), a rate-limiting translation initiation factor, causes an increase in CLN3 mRNA translation, which results in increased expression of CLN2 and in slow growth and decreased alpha-factor response. This phenotype was abrogated in a Deltacln3 or Deltacln2 background. We isolated the transcription factor MBP1 as a multicopy suppressor of the growth and alpha-factor response defects. Furthermore, elevated MBP1, a transcriptional regulator of cyclins, altered the transcriptional start site in CLN3 mRNA, shifting it 45 nucleotides upstream of the normal. This lengthened 5'-untranslated region likely reduces translation efficiency and down-regulates CLN3 protein synthesis, thereby correcting for the excess translation promoted by elevated Cdc33. In addition, the CLN2 mRNA level returned to normal. We propose that regulation of translation initiation by Cdc33 plays a pivotal role in the activation of Start and cell cycle progression in budding yeast.

Pyrroloquinoline quinone (PQQ) and quinoprotein enzymes

This review summarises the characteristics, identification, and measurement of pyrroloquinoline quinone, the prosthetic group of bacterial quinoprotein dehydrogenases whose structures, mechanisms, and electron transport functions are described in detail. Type I alcohol dehydrogenase includes the "classic" methanol dehydrogenase; its x-ray structure and mechanism are discussed in detail. It is likely that its mechanism involves a direct hydride transfer rather than a mechanism involving a covalent adduct. The x-ray structure of a closely related ethanol dehydrogenase is also described. The type II alcohol dehydrogenase is a soluble quinohaemoprotein, having a C-terminal extension containing haem C, which provides an excellent opportunity for the study of intraprotein electron transfer processes. The type III alcohol dehydrogenase is similar but it has two additional subunits (one of which is a multihaem cytochrome c) bound in an unusual way to the periplasmic membrane. One type of glucose dehydrogenase is a soluble quinoprotein whose role in energy transduction is uncertain. Its x-ray structure (in the presence and absence of substrate) is described together with the detailed mechanism, which also involves a direct hydride transfer. The more widely distributed glucose dehydrogenases are integral membrane proteins, bound to the membrane by transmembrane helices at the N-terminus.

Site-directed mutagenesis and X-ray crystallography of the PQQ-containing quinoprotein methanol dehydrogenase and its electron acceptor, cytochrome c(L)

Two proteins specifically involved in methanol oxidation in the methylotrophic bacterium Methylobacterium extorquens have been modified by site-directed mutagenesis. Mutation of the proposed active site base (Asp303) to glutamate in methanol dehydrogenase (MDH) gave an active enzyme (D303E-MDH) with a greatly reduced affinity for substrate and with a lower activation energy. Results of kinetic and deuterium isotope studies showed that the essential mechanism in the mutant protein was unchanged, and that the step requiring activation by ammonia remained rate limiting. No spectrally detectable intermediates could be observed during the reaction. The X-ray structure, determined to 3 A resolution, of D303E-MDH showed that the position and coordination geometry of the Ca2+ ion in the active site was altered; the larger Glu303 side chain was coordinated to the Ca2+ ion and also hydrogen bonded to the O5 atom of pyrroloquinoline quinone (PQQ). The properties and structure of the D303E-MDH are consistent with the previous proposal that the reaction in MDH is initiated by proton abstraction involving Asp303, and that the mechanism involves a direct hydride transfer reaction. Mutation of the two adjacent cysteine residues that make up the novel disulfide ring in the active site of MDH led to an inactive enzyme, confirming the essential role of this remarkable ring structure. Mutations of cytochrome c(L), which is the electron acceptor from MDH was used to identify Met109 as the sixth ligand to the heme.

The impact of virtual simulation in palliative radiotherapy for non-small-cell lung cancer

BACKGROUND AND PURPOSE

Radiotherapy is widely used to palliate local symptoms in non-small-cell lung cancer. Using conventional X-ray simulation, it is often difficult to accurately localize the extent of the tumour. We report a randomized, double blind trial comparing target localization with conventional and virtual simulation.

METHODS

Eighty-six patients underwent both conventional and virtual simulation. The conventional simulator films were compared with digitally reconstructed radiographs (DRRs) produced from the computed tomography (CT) data. The treatment fields defined by the clinicians using each modality were compared in terms of field area, position and the implications for target coverage.

RESULTS

Comparing fields defined by each study arm, there was a major mis-match in coverage between fields in 66.2% of cases, and a complete match in only 5.2% of cases. In 82.4% of cases, conventional simulator fields were larger (mean 24.5+/-5.1% (95% confidence interval)) than CT-localized fields, potentially contributing to a mean target under-coverage of 16.4+/-3.5% and normal tissue over-coverage of 25.4+/-4.2%.

CONCLUSIONS

CT localization and virtual simulation allow more accurate definition of the target volume. This could enable a reduction in geographical misses, while also reducing treatment-related toxicity.

A translationally regulated Tousled kinase phosphorylates histone H3 and confers radioresistance when overexpressed

The gene Tousled of Arabidopsis Thaliana encodes a protein kinase which, when mutated, results in abnormal flower development. From a library of mRNAs that are translationally upregulated by overexpression of the translation initiation factor 4E, we identified a mammalian Tousled Like kinase (TLK1B). The human TLK1B mRNA contains a 5'UTR 1088-nt-long with two upstream AUG codons, and was found to be very inhibitory for translation. The TLK1B protein localizes almost exclusively to the nuclei. TLK1B overexpression in mammalian cells rendered them more resistant to ionizing radiation (IR). Purified TLK1B phosphorylated histone H3 at S(10) with high specificity both in a mix of core histones and in isolated chromatin, suggesting that histone H3 is a physiological substrate for TLK1B. Moreover, overexpression of TLK1B in transfected cells resulted in a higher degree of H3 phosphorylation. Expression of TLK1B in a yeast strain that harbors a temperature-sensitive mutation of the major H3 kinase, Ipl1, complemented the growth defect; restored normal levels of histone H3 phosphorylation; and increased their resistance to IR. Phosphorylation of H3 has been linked to the activation of the immediate-early genes upon mitogenic stimulation, and to chromatin condensation during mitotic/meiotic events. A possible role for TLK1B in radioprotection is discussed.

An unusual role of tryptophan in PQQ-containing quinoproteins

Methanol dehydrogenase is a bacterial quinoprotein containing PQQ at its active site, which is in the centre of a superbarrel structure made up of eight beta-sheets arranged radially as the blades of a propeller. A series of novel tryptophan-docking interactions between the beta-sheets make planar, stabilizing girdles around the periphery of the protein. The tryptophan residues form stacking interactions, and hydrogen bonds through their indole ring NH groups.

Translational regulation of ribonucleotide reductase by eukaryotic initiation factor 4E links protein synthesis to the control of DNA replication

Ribonucleotide reductase synthesizes dNDPs, a specific and limiting step in DNA synthesis, and can participate in neoplastic transformation when overexpressed. The small subunit (ribonucleotide reductase 2 (RNR2)) was cloned as a major product in a subtraction library from eukaryotic initiation factor 4E (eIF4E)-transformed cells (Chinese hamster ovary-4E (CHO-4E)). CHO-4E cells have 20-40-fold elevated RNR2 protein, reflecting an increased distribution of RNR2 mRNA to the heavy polysomes. CHO-4E cells display an altered cell cycle with shortened S phase, similar to cells selected for RNR2 overexpression with hydroxyurea. The function of ribonucleotide reductase as a checkpoint component of S progression was studied in yeast in which elevated eIF4E rescued S-arrested rnr2-68(ts) cells, by increasing recruitment of its mRNA to polysomes. Crosses between rnr2-68(ts) and mutant eIF4E (cdc33-1(ts)) engendered conditional synthetic lethality, with extreme sensitivity to hydroxyurea and the microtubule depolymerizing agent, benomyl. The double mutant (cdc33-1 rnr2-68) also identified a unique terminal phenotype, arrested with small bud and a randomly distributed single nucleus, which is distinct from those of both parental single mutants. This phenotype defines eIF4E and RNR2 as determinants in an important cell cycle checkpoint, in early/mid-S phase. These results also provide a link between protein and DNA synthesis and provide an explanation for cell cycle alterations induced by elevated eIF4E.

Characterization of the membrane quinoprotein glucose dehydrogenase from Escherichia coli and characterization of a site-directed mutant in which histidine-262 has been changed to tyrosine

The requirements for substrate binding in the quinoprotein glucose dehydrogenase (GDH) in the membranes of Escherichia coli are described, together with the changes in activity in a site-directed mutant in which His262 has been altered to a tyrosine residue (H262Y-GDH). The differences in catalytic efficiency between substrates are mainly related to differences in their affinity for the enzyme. Remarkably, it appears that, if a hexose is able to bind in the active site, then it is also oxidized, whereas some pentoses are able to bind (and act as competitive inhibitors), but are not substrates. The activation energies for the oxidation of hexoses and pentoses are almost identical. In a previously published model of the enzyme, His262 is at the entrance to the active site and appears to be important in holding the prosthetic group pyrroloquinoline quinone (PQQ) in place, and it has been suggested that it might play a role in electron transfer from the reduced PQQ to the ubiquinone in the membrane. The H262Y-GDH has a greatly diminished catalytic efficiency for all substrates, which is mainly due to a marked decrease in their affinities for the enzyme, but the rate of electron transfer to oxygen is unaffected. During the processing of the PQQ into the apoenzyme to give active enzyme, its affinity is markedly dependent on the pH, four groups with pK values between pH7 and pH8 being involved. Identical results were obtained with H262Y-GDH, showing that His262 it is not directly involved in this process.