Short-term risk prediction after major lower limb amputation: PERCEIVE study

BACKGROUND

The accuracy with which healthcare professionals (HCPs) and risk prediction tools predict outcomes after major lower limb amputation (MLLA) is uncertain. The aim of this study was to evaluate the accuracy of predicting short-term (30 days after MLLA) mortality, morbidity, and revisional surgery.

METHODS

The PERCEIVE (PrEdiction of Risk and Communication of outcomE following major lower limb amputation: a collaboratIVE) study was launched on 1 October 2020. It was an international multicentre study, including adults undergoing MLLA for complications of peripheral arterial disease and/or diabetes. Preoperative predictions of 30-day mortality, morbidity, and MLLA revision by surgeons and anaesthetists were recorded. Probabilities from relevant risk prediction tools were calculated. Evaluation of accuracy included measures of discrimination, calibration, and overall performance.

RESULTS

Some 537 patients were included. HCPs had acceptable discrimination in predicting mortality (931 predictions; C-statistic 0.758) and MLLA revision (565 predictions; C-statistic 0.756), but were poor at predicting morbidity (980 predictions; C-statistic 0.616). They overpredicted the risk of all outcomes. All except three risk prediction tools had worse discrimination than HCPs for predicting mortality (C-statistics 0.789, 0.774, and 0.773); two of these significantly overestimated the risk compared with HCPs. SORT version 2 (the only tool incorporating HCP predictions) demonstrated better calibration and overall performance (Brier score 0.082) than HCPs. Tools predicting morbidity and MLLA revision had poor discrimination (C-statistics 0.520 and 0.679).

CONCLUSION

Clinicians predicted mortality and MLLA revision well, but predicted morbidity poorly. They overestimated the risk of mortality, morbidity, and MLLA revision. Most short-term risk prediction tools had poorer discrimination or calibration than HCPs. The best method of predicting mortality was a statistical tool that incorporated HCP estimation.

Abstract 374: Small intestinal organoids to study the effects of tight junction modulators that may improve the absorption of orally-administered, anti-neoplastic drugs

Although oral dosing is the most convenient route of drug administration, most anti-neoplastic drugs are administered intravenously due to poor bioavailability because of the epithelial barriers. A major organ involved in oral drug absorption is the small intestine where enterocytes are linked together by tight junctions (TJs). TJs regulate paracellular transport by creating a selectively-permeable barrier to small molecules, ions and water, thereby restricting the uptake of drugs. Transient modulation of the TJs is considered a potential strategy to improve drug delivery. Human small intestinal (SI) organoids are 3D in vitro models of the epithelium which recapitulate the structure and function of the small intestine. However, their geometry prevents access to the apical compartment of the epithelium (the outer, or luminal, surface being located within the organoid with the basal surface on the outside), making them unsuitable for the study of orally-administered drugs. Here we describe methods to generate transwell cell monolayers and inverted or ‘apical-out’ organoids, both derived from normal human small intestine, that allow direct access to the apical surface. We demonstrate that both formats provide an in vivo-like cell composition, comprising of all the intestinal cellular types, including stem cells, Paneth cells, goblet cells, enteroendocrine cells and enterocytes, and respond to treatment with ‘tool drug’ TJ modulators such as sodium caprate, chitosan, EGTA and various cytokines. Briefly, for the generation of transwell-grown cell monolayers, SI organoids were dissociated into single cells and plated in matrix-coated transwell inserts. The monolayer formation was followed by live imaging and Trans-Epithelial Electrical Resistance (TEER) measurements. Treatments with TJ modulators were applied after TEER reached a plateau and effects on TJs were evaluated by TEER reduction, FITC-Dextran permeability increase and analysis of TJ proteins by immunofluorescence. For the generation of apical-out organoids, SI organoids were mechanically broken into fragments and seeded in low adhesion plates until the organoids switched polarity. Treatments with TJ modulators were applied and effects on TJs were evaluated by immunofluorescence. In conclusion, our models provide an innovative in vitro solution to study the effect of TJ modulators on increasing paracellular transport of orally-administered, anti-neoplastic drugs. Furthermore, as anti-neoplastic drugs can also have toxic effects on the intestinal epithelium by affecting TJs, thereby creating a leaky barrier, the models are useful to predict such effects and stratify drug candidates prior to in vivo studies.

Citation Format: Valentina Ubertini, Stephanie French, James Wilson, Frida Ponthan. Small intestinal organoids to study the effects of tight junction modulators that may improve the absorption of orally-administered, anti-neoplastic drugs [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 374.

Quality Measures and Quality Improvement Initiatives in Osteoporosis-an Update

PURPOSE OF REVIEW

The aims of this review are to summarize current performance for osteoporosis quality measures used by Centers for Medicare and Medicaid (CMS) for pay-for-performance programs and to describe recent quality improvement strategies around these measures.

RECENT FINDINGS

Healthcare Effectiveness Data and Information (HEDIS) quality measures for the managed care population indicate gradual improvement in osteoporosis screening, osteoporosis identification and treatment following fragility fracture, and documentation of fall risk assessment and plan of care between 2006 and 2016. However, population-based studies suggest achievement for these process measures is lower where reporting is not mandated. Performance gaps remain, particularly for post-fracture care. Elderly patients with increased comorbidity are especially vulnerable to fractures, yet underperformance is documented in this population. Gender and racial disparities also exist. As has been shown for other areas of health care, education alone has a limited role as a quality improvement intervention. Multifactorial and systems-based interventions seem to be most successful in leading to measurable change for osteoporosis care and fall prevention. Despite increasing recognition of evidence-based quality measures for osteoporosis and incentives to improve upon performance for these measures, persistent gaps in care exist that will require further investigation into sustainable and value-adding quality improvement interventions.

Quantification of Oxygen Consumption in Retina Ex Vivo Demonstrates Limited Reserve Capacity of Photoreceptor Mitochondria

PURPOSE

Cell death in neurodegeneration occurs at the convergence of diverse metabolic pathways. In the retina, a common underlying mechanism involves mitochondrial dysfunction since photoreceptor homeostasis and survival are highly susceptible to altered aerobic energy metabolism. We sought to develop an assay to directly measure oxygen consumption in intact retina with the goal of identifying alterations in respiration during photoreceptor dysfunction and degeneration.

METHODS

Circular punches of freshly isolated mouse retina, adjacent to the optic nerve head, were used in the microplate-based Seahorse Extracellular Flux Analyzer to measure oxygen consumption. Tissue integrity was evaluated by propidium iodide staining and live imaging. Different substrates were tested for mitochondrial respiration. Basal and maximal respiration were expressed as oxygen consumption rate (OCR) and respectively measured in Ames' medium before and after the addition of mitochondrial uncoupler, BAM15.

RESULTS

We show that glucose is an essential substrate for retinal mitochondria. At baseline, mitochondria respiration in the intact wild-type retina was close to maximal, with limited reserve capacity. Similar OCR and limited mitochondrial reserve capacity was also observed in cone-only Nrl-/- retina. However, the retina of Pde6brd1/rd1, Cep290rd16/rd16 and Rpgrip1-/- mice, all with dysfunctional or no photoreceptors, had reduced OCR and higher mitochondrial reserve capacity.

CONCLUSIONS

We have optimized a method to directly measure oxygen consumption in acutely isolated, ex vivo mouse retina and demonstrate that photoreceptors have low mitochondrial reserve capacity. Our data provide a plausible explanation for the high vulnerability of photoreceptors to altered energy homeostasis caused by mutations or metabolic challenges.

Pulmonary Veno-Occlusive Disease

Pulmonary hypertension is a well-known though poorly characterized disease in veterinary medicine. In humans, pulmonary veno-occlusive disease (PVOD) is a rare cause of severe pulmonary hypertension with a mean survival time of 2 years without lung transplantation. Eleven adult dogs (5 males, 6 females; median age 10.5 years, representing various breeds) were examined following the development of severe respiratory signs. Lungs of affected animals were evaluated morphologically and with immunohistochemistry for alpha smooth muscle actin, desmin, CD31, CD3, CD20, and CD204. All dogs had pulmonary lesions consistent with PVOD, consisting of occlusive remodeling of small- to medium-sized pulmonary veins, foci of pulmonary capillary hemangiomatosis (PCH), and accumulation of hemosiderophages; 6 of 11 dogs had substantial pulmonary arterial medial and intimal thickening. Ultrastructural examination and immunohistochemistry showed that smooth muscle cells contributed to the venous occlusion. Increased expression of CD31 was evident in regions of PCH indicating increased numbers of endothelial cells in these foci. Spindle cells strongly expressing alpha smooth muscle actin and desmin co-localized with foci of PCH; similar cells were present but less intensely labeled elsewhere in non-PCH alveoli. B cells and macrophages, detected by immunohistochemistry, were not co-localized with the venous lesions of canine PVOD; small numbers of CD3-positive T cells were occasionally in and around the wall of remodeled veins. These findings indicate a condition in dogs with clinically severe respiratory disease and pathologic features resembling human PVOD, including foci of pulmonary venous remodeling and PCH.

In vivo microscopy reveals extensive embedding of capillaries within the sarcolemma of skeletal muscle fibers

OBJECTIVE

To provide insight into mitochondrial function in vivo, we evaluated the 3D spatial relationship between capillaries, mitochondria, and muscle fibers in live mice.

METHODS

3D volumes of in vivo murine TA muscles were imaged by MPM. Muscle fiber type, mitochondrial distribution, number of capillaries, and capillary-to-fiber contact were assessed. The role of Mb-facilitated diffusion was examined in Mb KO mice. Distribution of GLUT4 was also evaluated in the context of the capillary and mitochondrial network.

RESULTS

MPM revealed that 43.6 ± 3.3% of oxidative fiber capillaries had ≥50% of their circumference embedded in a groove in the sarcolemma, in vivo. Embedded capillaries were tightly associated with dense mitochondrial populations lateral to capillary grooves and nearly absent below the groove. Mitochondrial distribution, number of embedded capillaries, and capillary-to-fiber contact were proportional to fiber oxidative capacity and unaffected by Mb KO. GLUT4 did not preferentially localize to embedded capillaries.

CONCLUSIONS

Embedding capillaries in the sarcolemma may provide a regulatory mechanism to optimize delivery of oxygen to heterogeneous groups of muscle fibers. We hypothesize that mitochondria locate to PV regions due to myofibril voids created by embedded capillaries, not to enhance the delivery of oxygen to the mitochondria.

Stimulation of oxidative phosphorylation by calcium in cardiac mitochondria is not influenced by cAMP and PKA activity

Cardiac oxidative ATP generation is finely tuned to match several-fold increases in energy demand. Calcium has been proposed to play a role in the activation of ATP production via PKA phosphorylation in response to intramitochondrial cAMP generation. We evaluated the effect of cAMP, its membrane permeable analogs (dibutyryl-cAMP, 8-bromo-cAMP), and the PKA inhibitor H89 on respiration of isolated pig heart mitochondria. cAMP analogs did not stimulate State 3 respiration of Ca2 +-depleted mitochondria (82.2 ± 3.6% of control), in contrast to the 2-fold activation induced by 0.95 μM free Ca2 +, which was unaffected by H89. Using fluorescence and integrating sphere spectroscopy, we determined that Ca2 + increased the reduction of NADH (8%), and of cytochromes bH (3%), c1 (3%), c (4%), and a (2%), together with a doubling of conductances for Complex I + III and Complex IV. None of these changes were induced by cAMP analogs nor abolished by H89. In Ca2 +-undepleted mitochondria, we observed only slight changes in State 3 respiration rates upon addition of 50 μM cAMP (85 ± 9.9%), dibutyryl-cAMP (80.1 ± 5.2%), 8-bromo-cAMP (88.6 ± 3.3%), or 1 μM H89 (89.7 ± 19.9%) with respect to controls. Similar results were obtained when measuring respiration in heart homogenates. Addition of exogenous PKA with dibutyryl-cAMP or the constitutively active catalytic subunit of PKA to isolated mitochondria decreased State 3 respiration by only 5–15%. These functional studies suggest that alterations in mitochondrial cAMP and PKA activity do not contribute significantly to the acute Ca2 + stimulation of oxidative phosphorylation

Genetic mosaic analysis of a deleterious mitochondrial DNA mutation in Drosophila reveals novel aspects of mitochondrial regulation and function

A lethal mtDNA mutation affecting COX is fully rescued by AOX. The mutant genome level remains constant in the somatic tissues along the aging process in heteroplasmic flies. A genetic scheme creates tissue-specific heteroplasmy in otherwise heteroplasmic background and reveals that Ca2⁺ mishandling contributes to the neurodegeneration.

Various human diseases are associated with mitochondrial DNA (mtDNA) mutations, but heteroplasmy—the coexistence of mutant and wild-type mtDNA—complicates their study. We previously isolated a temperature-lethal mtDNA mutation in Drosophila, mt:CoI^T300I, which affects the cytochrome c oxidase subunit I (CoI) locus. In the present study, we found that the decrease in cytochrome c oxidase (COX) activity was ascribable to a temperature-dependent destabilization of cytochrome a heme. Consistently, the viability of homoplasmic flies at 29°C was fully restored by expressing an alternative oxidase, which specifically bypasses the cytochrome chains. Heteroplasmic flies are fully viable and were used to explore the age-related and tissue-specific phenotypes of mt:CoI^T300I. The proportion of mt:CoI^T300I genome remained constant in somatic tissues along the aging process, suggesting a lack of quality control mechanism to remove defective mitochondria containing a deleterious mtDNA mutation. Using a genetic scheme that expresses a mitochondrially targeted restriction enzyme to induce tissue-specific homoplasmy in heteroplasmic flies, we found that mt:CoI^T300I homoplasmy in the eye caused severe neurodegeneration at 29°C. Degeneration was suppressed by improving mitochondrial Ca²⁺ uptake, suggesting that Ca²⁺ mishandling contributed to mt:CoI^T300I pathogenesis. Our results demonstrate a novel approach for Drosophila mtDNA genetics and its application in modeling mtDNA diseases.

Optical spectroscopy in turbid media using an integrating sphere: mitochondrial chromophore analysis during metabolic transitions

Recent evidence suggests that the activity of mitochondrial oxidative phosphorylation complexes (MOPCs) is modulated at multiple sites. Here, a method of optically monitoring electron distribution within and between MOPCs is described using a center-mounted sample in an integrating sphere (to minimize scattering effects) with a rapid-scanning spectrometer. The redox-sensitive MOPC absorbances (∼465-630 nm) were modeled using linear least squares analysis with individual chromophore spectra. Classical mitochondrial activity transitions (e.g., ADP-induced increase in oxygen consumption) were used to characterize this approach. Most notable in these studies was the observation that intermediates of the catalytic cycle of cytochrome oxidase are dynamically modulated with metabolic state. The MOPC redox state, along with measurements of oxygen consumption and mitochondrial membrane potential, was used to evaluate the conductances of different sections of the electron transport chain. This analysis then was applied to mitochondria isolated from rabbit hearts subjected to ischemia/reperfusion (I/R). Surprisingly, I/R resulted in an inhibition of all measured MOPC conductances, suggesting a coordinated down-regulation of mitochondrial activity with this well-established cardiac perturbation.

Role of routine chest radiographs in the evaluation of patients with stable blunt chest trauma--a prospective analysis

OBJECTIVE

The study sought to assess the test performance characteristics of clinical judgement in the evaluation of stable blunt chest trauma patients compared with chest radiography (CXR) in the determination of significant intra-thoracic injury.

METHODS

We prospectively enrolled all adult patients (older than 16years) who were considered to have stable blunt chest trauma over a six-month period (May 1-October 31, 2009). We defined the latter as patients who were unintubated, normotensive (systolic blood pressure > 90 mm Hg) and without hypoxia (oxygen saturation> 95% at room air). Patients eligible for the study were sent for anteroposterior (AP) CXRs which were then interpreted by the same consultant radiologist throughout the study period. Both test (clinical judgement) and disease status (CXR) were assigned and correlated as binary measures. We compared the test performance characteristics such as sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and diagnostic likelihood ratios of clinical judgement to CXR findings in the determination of significant intra-thoracic injury.

RESULTS

During the six-month period, data were collected from 77 eligible stable blunt chest trauma patients (age over 16 years). Fifty-nine patients (76.6%) were male. Nine patients (11.7%) were radiologically confirmed to have significant blunt chest injuries including rib fractures, pneumothorax and an isolated case of pulmonary contusion. All nine (11.7%) patients had a positive (abnormal) radiograph for rib fractures. In addition, three (3.9%) of them also had both rib fracture and pneumothoraces and one (1.3%) had both a rib fracture and pulmonary contusion. Clinical judgementfor the diagnosis of significant blunt chest injuries matched with the CXR finding with 95% confidence intervals (CIs): sensitivity 100% (95% CI 66.4, 100), specificity 32.4% (95% CI 21.5, 44.8), prevalence 11.7%, PPV 16.4% (95% CI 7.77, 28.8), NPV100% (95% CI 84.6, 100), DLR+ 1.48 (95% CI 1.25, 1.74).

CONCLUSION

The majority ofpatients who sustained blunt chest injuries and were assessed as stable patients do not require CXR routinely. This study revealed that physicians in the local Emergency Department may be over-utilizing CXRfor patients who have stable blunt chest trauma.

[The chronic patient and the nurse-managed hospital unit]

In this article we discuss the implementation of a hospital nursing care unit in a local health authority in Rome (Italy), The hospital involved provides a wide range of healthcare and social services. The project is a very innovative one at the national level, with respect to healthcare services offered to patients with chronic disorders and associated disabilities. Starting from the concept of "centrality of the patient" in the area of healthcare services, we developed an organizational model where nursing care represents one of the basic elements.

Can a participatory approach contribute to food chain risk analysis?

We consider food chain risks and specifically address stakeholder participation in the risk analysis process. We combine social and natural science perspectives to explore the participation process in relation to food risks and, in particular, to consider how some specific participation processes might be scientifically evaluated and how stakeholder participation in general might be incorporated into food risk decision making. We have built considerations based on three large integrative case studies that examine aspects of participatory processes. Here we use the case studies collectively to illustrate observations and beliefs concerning the nature of the interaction of stakeholders with established quantitative risk methodologies. This account is not supported by any large volume of analysis. The views in the report are expressed in relation to an accepted risk analysis framework and also with respect to probabilistic modeling of risks and are illustrated where possible with anecdotal reports of actual case study events.

[In the heart of the district. 50 interviews with the health professionals of the Lazio Region districts, Italy]

This article aims to explore some key issues relating to the health districts of the Lazio Region, in particular the major critical aspects as well as some strengths highlighted by the operators. In the Lazio Region there are 12 Local Health Units, divided into 55 health districts. In recent years, the majority of the authors analized theoretical models proposed by regional standards, while the strengths and weaknesses of the district, as well as the organizational difficulties and problems experienced daily by the operators have not been investigated. It was decided to use qualitative methods of research, through open interviews with 50 operators in 15 health districts of the Region. Interviews were analysed utilizing software Nvivo. Some codes were identified to guide interviews. We can summarize the emergency issues at least in three major areas: 1) the organization of the district, 2) the management of personnel and resources, 3) the care pathways. It is hoped that, during next years, the research directed at health district analysis will grow, with particular reference to quantitative and qualitative investigations, in order to build a body of knowledge from practical experience of health professionals.

Staining for intracytoplasmic lumina and CAM5.2 increases the detection rate for bile duct cancers

BACKGROUND AND STUDY AIMS

Endoscopic biopsies have a low sensitivity for diagnosing malignant bile duct strictures. Tumor markers detected by mucin staining and immunohistochemistry may help to determine the malignancy of a biopsy specimen where histologic evaluation alone is nondiagnostic.

PATIENTS AND METHODS

61 patients who underwent forceps biopsies were retrospectively identified, yielding 49 and 40 biopsy specimens for strictures finally diagnosed as benign and malignant, respectively. Biopsy specimens were histologically evaluated and stained for p53, Ki-67, carcinoembryonic antigen (CEA), CA19-9, CAM5.2, and presence of intracytoplasmic lumina (ICL). Sensitivity, specificity, positive and negative predictive values (PPV and NPV), and positive and negative likelihood ratios (PLR and NLR) were calculated to evaluate the performance of each test.

RESULTS

Histology alone provided sensitivity and specificity of 53 % and 100 %. Addition of ICL or CAM5.2 increased sensitivity to 73 % or 60 %, respectively, and provided excellent specificity, PPV, and PLR (ICL, 98 %, 97 %, and 36; CAM5.2, 100 %, 100 %, and infinite). Both stains in combination increased the sensitivity to 75 %. Staining for Ki-67, p53, CEA, and CA19-9 increased the sensitivity to detect malignancy (range 60 % to 83 %), but significantly reduced the specificity, PPV and PLR (ranges 73 % to 90 %, 72 % to 86 %, and 3 to 7, respectively). Markers in all combinations performed poorly as a negative test (NPV 69 % to 87 %, and NLR 0.19 to 0.55).

CONCLUSIONS

Staining for tumor markers ICL and CAM5.2 can improve the diagnostic value of endoscopic biopsies, and may change the course of management for patients with indeterminate histological findings.

Delays in presentations of stroke patients at the University Hospital of the West Indies

Thrombolytic therapy has been proven to be beneficial in selected patients with ischaemic strokes. Early diagnosis is paramount because there is a narrow therapeutic window for these patients to derive benefit from thrombolytics. We sought to evaluate the timing of stroke presentations at the University Hospital of the West Indies (UHWI) in order to assess the potential eligibility for definitive therapy A retrospective audit of all consecutive patients who had emergent computed tomographic (CT) scans for suspected ischaemic stroke at the UHWI was performed over a six-month period between February 2006 and July 2006. Data were extracted from the hospital records and analysed using SPSS version 12. There were 331 patients evaluated with brain CT for a clinically suspected stroke during the study period. Complete time documentation and CT scans were available for analysis in 171 patients with ischaemic strokes. The average age was 64.5 years (range +/- SD: 3-98 +/- 19.9 years) with a slight male preponderance (58% vs. 42%). There was considerable pre-hospital delay with 63% of patients presenting more than 12 hours after the onset of symptoms. There were also long inhospital delays. Only 52% of patients were assessed by a physician within an hour of presentation to hospital and only 55% of patients had CT scans completed within three hours of a physician s request. Although thrombolysis is not routinely performed for ischaemic strokes at our institution, sensitization of physicians and the general public in our setting to symptoms and signs of this disease is urgently needed to improve stroke management, whereby definitive treatment can be considered for selected patients.

Use of (32)P to study dynamics of the mitochondrial phosphoproteome

Protein phosphorylation is a well-characterized regulatory mechanism in the cytosol, but remains poorly defined in the mitochondrion. In this study, we characterized the use of (32)P-labeling to monitor the turnover of protein phosphorylation in the heart and liver mitochondria matrix. The (32)P labeling technique was compared and contrasted to Phos-tag protein phosphorylation fluorescent stain and 2D isoelectric focusing. Of the 64 proteins identified by MS spectroscopy in the Phos-Tag gels, over 20 proteins were correlated with (32)P labeling. The high sensitivity of (32)P incorporation detected proteins well below the mass spectrometry and even 2D gel protein detection limits. Phosphate-chase experiments revealed both turnover and phosphate associated protein pool size alterations dependent on initial incubation conditions. Extensive weak phosphate/phosphate metabolite interactions were observed using nondisruptive native gels, providing a novel approach to screen for potential allosteric interactions of phosphate metabolites with matrix proteins. We confirmed the phosphate associations in Complexes V and I due to their critical role in oxidative phosphorylation and to validate the 2D methods. These complexes were isolated by immunocapture, after (32)P labeling in the intact mitochondria, and revealed (32)P-incorporation for the alpha, beta, gamma, OSCP, and d subunits in Complex V and the 75, 51, 42, 23, and 13a kDa subunits in Complex I. These results demonstrate that a dynamic and extensive mitochondrial matrix phosphoproteome exists in heart and liver.

Proteomic changes associated with diabetes in the BB-DP rat

These studies were structured with the aim of utilizing emerging technologies in two-dimensional (2D) gel electrophoresis and mass spectrometry to evaluate protein expression changes associated with type 1 diabetes. We reasoned that a broad examination of diabetic tissues at the protein level might open up novel avenues of investigation of the metabolic and signaling pathways that are adversely affected in type 1 diabetes. This study compared the protein expression of the liver, heart, and skeletal muscle of diabetes-prone rats and matched control rats by semiquantitative liquid chromatography-mass spectrometry and differential in-gel 2D gel electrophoresis. Differential expression of 341 proteins in liver, 43 in heart, and 9 (2D gel only) in skeletal muscle was detected. These data were assembled into the relevant metabolic pathways affected primarily in liver. Multiple covalent modifications were also apparent in 2D gel analysis. Several new hypotheses were generated by these data, including mechanisms of net cytosolic protein oxidation, formaldehyde generation by the methionine cycle, and inhibition of carbon substrate oxidation via reduction in citrate synthase and short-chain acyl-CoA dehydrogenase.

32P labeling of protein phosphorylation and metabolite association in the mitochondria matrix

Protein phosphorylations, as well as phosphate metabolite binding, are well characterized post-translational mechanisms that regulate enzyme activity in the cytosol, but remain poorly defined in mitochondria. Recently extensive matrix protein phosphorylation sites have been discovered but their functional significance is unclear. Herein we describe methods of using (32)P labeling of intact mitochondria to determine the dynamic pools of protein phosphorylation as well as phosphate metabolite association. This screening approach may be useful in not only characterizing the dynamics of these pools, but also provide insight into which phosphorylation sites have a functional significance. Using the mitochondrial ATP synthetic capacity under appropriate conditions, inorganic (32)P was added to energized mitochondria to generate high specific activity gamma-P(32)-ATP in the matrix. In general, SDS denaturing and gel electrophoresis was used to primarily follow protein phosphorylation, whereas native gel techniques were used to observe weaker metabolite associations since the structure of mitochondrial complexes was minimally affected. The protein phosphorylation and metabolite association within the matrix was found to be extensive using these approaches. (32)P labeling in 2D gels was detected in over 40 proteins, including most of the complexes of the cytochrome chain and proteins associated with intermediary metabolism, biosynthetic pathways, membrane transport, and reactive oxygen species metabolism. (32)P pulse-chase experiments further revealed the overall dynamics of these processes that included phosphorylation site turnover as well as phosphate-protein pool size alterations. The high sensitivity of (32)P resulted in many proteins being intensely labeled, but not identified due to the sensitivity limitations of mass spectrometry. These low concentration proteins may represent signaling proteins within the matrix. These results demonstrate that the mitochondrial matrix phosphoproteome is both extensive and dynamic. The use of this, in situ, labeling approach is extremely valuable in confirming protein phosphorylation sites as well as examining the dynamics of these processes under near physiological conditions.

Pilot series of radiofrequency ablation of Barrett's esophagus with or without neoplasia

BACKGROUND AND STUDY AIMS

Radiofrequency ablation is a rapidly evolving therapeutic modality for Barrett's esophagus. The aim of this ongoing 12-month trial is to assess Barrett's esophagus eradication after radiofrequency ablation using a balloon-based (HALO-360) and a plate-based (HALO-90) device. We report here our experience with the first 10 patients (out of 40) who have completed 12 months of follow-up.

PATIENTS AND METHODS

Following radiofrequency ablation using the HALO-360 device all patients were maintained on double-dose proton pump inhibitor therapy. Endoscopic evaluation was performed at 3 and 12 months postablation. Patients with residual Barrett's esophagus at 3 months underwent repeat ablation. Ten patients, seven with nondysplastic Barrett's esophagus, two with low-grade and one with high-grade dysplasia have completed the study to date.

RESULTS

Complete Barrett's esophagus eradication was achieved in seven patients, and partial eradication was achieved in three. There were no major complications. One case of buried Barrett's metaplasia was encountered and successfully re-ablated, with complete Barrett's esophagus eradication achieved at 12 months.

CONCLUSIONS

In this study, Barrett's eradication rates were comparable to previously published reports. One case of buried Barrett's metaplasia was identified out of 247 biopsies and was eradicated with repeat ablation.

The evolution of emergency medicine in Jamaica

Emergency Medicine in Jamaica has evolved rapidly over the past 20 years and has gained recognition as a specialty. A residency training programme has been established, trademark life support courses are now available, moves to develop areas of sub-specialization have begun and an emergency medicine association has been formed. There has been an increase in the diagnostic modalities in the main teaching institution, the University Hospital of the West Indies (UHWI). There is an urgent need for improvements in pre-hospital care. This will require the development of an efficient Emergency Medical Service (EMS). More emphasis and attention is required on disaster medicine, toxicology and trauma. Increased training of emergency physicians and nurses, advances in academia and research, and greater advocacy by local emergency physicians will further advance the specialty.

Penetrating neck trauma and the aberrant subclavian artery

Vascular injuries from penetrating trauma to the base of the neck are accompanied by significant morbidity and potential mortality. These injuries require several diagnostic adjuncts in order to facilitate early diagnosis and appropriate treatment. Herein reported is the case of a patient who sustained penetrating injury to the thoracic inlet but had a fortuitous anomaly that prevented vascular injury and its attendant complications.

Association between exposure/non-exposure to the mandatory seat belt law with regards to compliance in vehicle accident victims--a hospital review

OBJECTIVE

Injuries sustained in motor vehicle accidents (MVAs) are a major challenge to the Jamaican healthcare system. In November 1999, Jamaica enacted legislation to make seat belt usage in motor vehicles compulsory. The effect of this policy change on seat belt usage is unclear. This study therefore sought to determine the prevalence of seat belt usage and to determine the association between exposure/non-exposure to the mandatory seat belt law and seat belt use in subjects who presented to the Accident and Emergency Department (A&E) of the University Hospital of the West Indies (UHWI) as a result of motor vehicle accidents.

METHODS

Subjects were recruited from June to November 2003, post-seat belt law (POBL) period, and May to October 1999, pre-seat belt law (PRBL) period. Data collected included demographic variables, seat belt use and position of the occupants in the vehicle.

RESULTS

Of the 277 patients who were eligible for inclusion, data were complete in 258 subjects, 87 in the PRBL period and 171 in the POBL period. The prevalence of seat belt use was 47% (PRBL) and 63% (POBL) respectively. There was no significant gender difference at each period. The odds of wearing seat belt in the rear of a motor vehicle were significantly lower than that of a driver (Table 3, OR 0.19, 95% CI 0.07, 0.48). Adjusting for age, gender and position in vehicle exposure, there was about 100% increase in the odds of seat belt use during the post seat belt law era (OR = 2.09, 95% CI 1.21, 3.61).

CONCLUSION

It is concluded from this hospital-based study that the mandatory seat belt law legislature was associated with increased seat belt use in motor vehicle accident victims. However, current data from the Road Traffic Agency indicate that there is still an alarming number of fatalities. This clearly suggests that additional public health measures are needed to address the epidemic of motor vehicle trauma in Jamaica.

What young Dutch adults say they do to keep from gaining weight: self-reported prevalence of overeating, compensatory behaviours and specific weight control behaviours

OBJECTIVE

The aim of this study was to explore the prevalence of and differences in self-reported occasions of overeating (such as at celebrations and other parties), compensatory behaviours and specific weight gain prevention strategies among young Dutch adults according to sociodemographics and overweight status.

DESIGN AND SUBJECTS

Cross-sectional data were analysed from Dutch adults aged 20-40 years, recruited from an Internet research panel (n = 857, response rate = 76.6%). Using electronic questionnaires, self-report data were collected on sociodemographics, body mass index (BMI), occasions of overeating, compensatory behaviours, and diet and physical activity used as weight gain prevention strategies. Associations were tested using multiple linear and logistic regression analyses.

RESULTS

Of the participants, 48.6% reported occasions of overeating at least once a week during the 4-week period, 44.6% reported compensating for these occasions and 72.9% reported engaging in dietary and physical activities specifically for weight gain prevention purposes. Only 32.1% of the respondents reported using the recommended combination of diet and physical activity as a weight gain prevention strategy. In addition, results showed that overweight people (BMI > or = 25 kg m-2) and women were more likely to report overeating than people with healthy body weights (odds ratio (OR) = 1.79; 95% confidence interval (CI) 1.32-2.42) and men (OR = 1.50; 95% CI 1.14-1.97). Overweight people, women and people who regularly reported overeating were also significantly more likely to report compensatory behaviours by eating less and to report specific weight gain prevention strategies using diet and physical activity.

CONCLUSION

The present study suggests that people experience frequent occasions of overeating and try to compensate for such occasions in different ways. However, the combination of dietary changes and physical activity recommended by experts was seldom reported.

Tissue heterogeneity of the mammalian mitochondrial proteome

The functionality of the mitochondrion is primarily determined by nuclear encoded proteins. The mitochondrial functional requirements of different tissues vary from a significant biosynthetic role (liver) to a primarily energy metabolism-oriented organelle (heart). The purpose of this study was to compare the mitochondrial proteome from four different tissues of the rat, brain, liver, heart, and kidney, to provide insight into the extent of mitochondrial heterogeneity and to further characterize the overall mitochondrial proteome. Mitochondria were isolated, solubilized, digested, and subjected to quantitative liquid chromatography-mass spectroscopy. Of the 16,950 distinct peptides detected, 8,045 proteins were identified. High-confidence identification threshold was reached by 1,162 peptides, which were further analyzed. Of these 1,162 proteins, 1,149 were significantly different in content ( P and q values < 0.05) between at least 2 tissues, whereas 13 were not significantly different between any tissues. Confirmation of the mitochondrial origin of proteins was determined from the literature or via NH2-terminal mitochondrial localization signals. With these criteria, 382 proteins in the significantly different groups were confirmed to be mitochondrial, and 493 could not be confirmed to be mitochondrial but were not definitively localized elsewhere in the cell. A total of 145 proteins were assigned to the rat mitochondrial proteome for the first time via their NH2-terminal mitochondrial localization signals. Among the proteins that were not significantly different between tissues, three were confirmed to be mitochondrial. Most notable of the significantly different proteins were histone family proteins and several structural proteins, including tubulin and intermediate filaments. The mitochondrial proteome from each tissue had very specific characteristics indicative of different functional emphasis. These data confirm the notion that mitochondria are tuned by the nucleus for specific functions in different tissues.

Are current processes for nuclear emergency management in Europe adequate?

We describe the results of process mapping of nuclear emergency management procedures in four European countries. We find clear differences and explore these in relation to their suitability for building a shared understanding across the emergency management team of the evolving situation and a balanced appreciation of the uncertainties. Our findings indicate that there are some issues that cause concern in that the procedures may run smoothly and efficiently but they may also risk underestimating uncertainty or ignore key issues that have only been identified by a minority of experts or models. We are concerned that they do not facilitate the building of shared mental models that the literature such as that on highly reliable organisations has shown is important.

Mitochondrial matrix phosphoproteome: effect of extra mitochondrial calcium

Post-translational modification of mitochondrial proteins by phosphorylation or dephosphorylation plays an essential role in numerous cell signaling pathways involved in regulating energy metabolism and in mitochondrion-induced apoptosis. Here we present a phosphoproteomic screen of the mitochondrial matrix proteins and begin to establish the protein phosphorylations acutely associated with calcium ions (Ca(2+)) signaling in porcine heart mitochondria. Forty-five phosphorylated proteins were detected by gel electrophoresis-mass spectrometry of Pro-Q Diamond staining, while many more Pro-Q Diamond-stained proteins evaded mass spectrometry detection. Time-dependent (32)P incorporation in intact mitochondria confirmed the extensive matrix protein phosphoryation and revealed the dynamic nature of this process. Classes of proteins that were detected included all of the mitochondrial respiratory chain complexes, as well as enzymes involved in intermediary metabolism, such as pyruvate dehydrogenase (PDH), citrate synthase, and acyl-CoA dehydrogenases. These data demonstrate that the phosphoproteome of the mitochondrial matrix is extensive and dynamic. Ca(2+) has previously been shown to activate various dehydrogenases, promote the generation of reactive oxygen species (ROS), and initiate apoptosis via cytochrome c release. To evaluate the Ca(2+) signaling network, the effects of a Ca(2+) challenge sufficient to release cytochrome c were evaluated on the mitochondrial phosphoproteome. Novel Ca(2+)-induced dephosphorylation was observed in manganese superoxide dismutase (MnSOD) as well as the previously characterized PDH. A Ca(2+) dose-dependent dephosphorylation of MnSOD was associated with an approximately 2-fold maximum increase in activity; neither the dephosphorylation nor activity changes were induced by ROS production in the absence of Ca(2+). These data demonstrate the use of a phosphoproteome screen in determining mitochondrial signaling pathways and reveal new pathways for Ca(2+) modification of mitochondrial function at the level of MnSOD.

The mammalian longevity-associated gene product p66shc regulates mitochondrial metabolism

Previous studies have determined that mice with a homozygous deletion in the adapter protein p66(shc) have an extended life span and that cells derived from these mice exhibit lower levels of reactive oxygen species. Here we demonstrate that a fraction of p66(shc) localizes to the mitochondria and that p66(shc-/-) fibroblasts have altered mitochondrial energetics. In particular, despite similar cytochrome content, under basal conditions, the oxygen consumption of spontaneously immortalized p66(shc-/-) mouse embryonic fibroblasts were lower than similarly maintained wild type cells. Differences in oxygen consumption were particularly evident under chemically uncoupled conditions, demonstrating that p66(shc-/-) cells have a reduction in both their resting and maximal oxidative capacity. We further demonstrate that reconstitution of p66(shc) expression in p66(shc-/-) cells increases oxygen consumption. The observed defect in oxidative capacity seen in p66(shc-/-) cells is partially offset by augmented levels of aerobic glycolysis. This metabolic switch is manifested by p66(shc-/-) cells exhibiting an increase in lactate production and a stricter requirement for extracellular glucose in order to maintain intracellular ATP levels. In addition, using an in vivo NADH photobleaching technique, we demonstrate that mitochondrial NADH metabolism is reduced in p66(shc-/-) cells. These results demonstrate that p66(shc) regulates mitochondrial oxidative capacity and suggest that p66(shc) may extend life span by repartitioning metabolic energy conversion away from oxidative and toward glycolytic pathways.