Which diagnostic tests are most useful in a chest pain unit protocol?

Background The chest pain unit (CPU) provides rapid diagnostic assessment for patients with acute, undifferentiated chest pain, using a combination of electrocardiographic (ECG) recording, biochemical markers and provocative cardiac testing. We aimed to identify which elements of a CPU protocol were most diagnostically and prognostically useful. Methods The Northern General Hospital CPU uses 2–6 hours of serial ECG / ST segment monitoring, CK-MB(mass) on arrival and at least two hours later, troponin T at least six hours after worst pain and exercise treadmill testing. Data were prospectively collected over an eighteen-month period from patients managed on the CPU. Patients discharged after CPU assessment were invited to attend a follow-up appointment 72 hours later for ECG and troponin T measurement. Hospital records of all patients were reviewed to identify adverse cardiac events over the subsequent six months. Diagnostic accuracy of each test was estimated by calculating sensitivity and specificity for: 1) acute coronary syndrome (ACS) with clinical myocardial infarction and 2) ACS with myocyte necrosis. Prognostic value was estimated by calculating the relative risk of an adverse cardiac event following a positive result. Results Of the 706 patients, 30 (4.2%) were diagnosed as ACS with myocardial infarction, 30 (4.2%) as ACS with myocyte necrosis, and 32 (4.5%) suffered an adverse cardiac event. Sensitivities for ACS with myocardial infarction and myocyte necrosis respectively were: serial ECG / ST segment monitoring 33% and 23%; CK-MB(mass) 96% and 63%; troponin T (using 0.03 ng/ml threshold) 96% and 90%. The only test that added useful prognostic information was exercise treadmill testing (relative risk 6 for cardiac death, non-fatal myocardial infarction or arrhythmia over six months). Conclusion Serial ECG / ST monitoring, as used in our protocol, adds little diagnostic or prognostic value in patients with a normal or non-diagnostic initial ECG. CK-MB(mass) can rule out ACS with clinical myocardial infarction but not myocyte necrosis(defined as a troponin elevation without myocardial infarction). Using a low threshold for positivity for troponin T improves sensitivity of this test for myocardial infarction and myocardial necrosis. Exercise treadmill testing predicts subsequent adverse cardiac events

Experience with posttransplant lymphoproliferative disorders in solid organ transplant recipients

Nearly 6000 solid organ transplants have been performed at the University of Pittsburgh since 1981. Posttransplant lymphoproliferative disorders (PTLD) have occurred in 131 patients, at a frequency of 2.2%. The majority of cases manifest within 6 months following allograft, but individual lesions may arise several years thereafter. From 1981 to 1989, cyclosporine-A (CsA) served as the primary immunosuppressant in this population. In March of 1989, FK506 was introduced for clinical trials. Since that time, 1421 patients have received FK506 either for primary immunosuppression or as rescue therapy. The frequency of PTLD in this subpopulation is 1.5%. PTLD arising under FK506-containing regimens have clinicopathologic features similar to those arising with CsA immunosuppression. The frequency of PTLD at this point in time is approximately 1%, in kidney allograft patients, 2.7% in liver, 3.3% in heart and 3.8%, in heart/lung or lung recipients. An understanding of the range of histologic appearance is important for the diagnosis of PTLD, especially when it involves the allograft itself. Immunoglobulin heavy chain gene analysis shows that lesions with no rearrangements or with a rearrangement in only a small proportion of cells are more likely to respond to reduced immunosuppression than are those with clonal rearrangement involving a high proportion of cells. However, this distinction is not absolute, and a trial of reduced immunosuppression appears to be indicated regardless of clonal status

Fretting corrosion of tin-plated separable connectors used in automotive applications

Greater demands are being placed on the separable connector to perform with higher reliability in harsher automotive environments. Corrosion in its various forms is a major mechanism which affects contact reliability and this current work focuses on surface oxidation and the related phenomenon of fretting corrosion, from which hot dipped tin (HDT), a common automotive connector coating, is known to suffer. For an in-depth study of high contact resistance, in both static conditions and when subjected to relative micromovement, an interdisciplinary approach was necessary, drawing on the results of published work carried out in the fields of contact and surface science, corrosion and tribology. [Continues.

Microtubule-dependent Organization of Vaccinia Virus Core-derivd Early mRNAs into Distinct Cytoplasmic Structures.

Vaccinia virus (vv) early transcription can be reconstituted in vitro from purified virions; in this assay mRNAs are made inside the viral core and subsequently extruded. Although the in vitro process has been extensively characterized, relatively little is known about vv early transcription in vivo. In the present study the fate of vv early mRNAs in infected HeLa cells was followed by BrUTP transfection and confocal and electron microscopy. The extruded vv early mRNAs were found to be organized into unique granular cytoplasmic structures that reached a size up to 1 μm. By EM these structures appeared as amorphous electron-dense cytoplasmic aggregates that were surrounded by ribosomes. Confocal images showed that the RNA structures were located some distance away from intracellular cores and that both structures appeared to be aligned on microtubules (MTs), implying that MT tracks connected mRNAs and cores. Accordingly, intact MTs were found to be required for the typical punctate organization of viral mRNAs. Biochemical evidence supported the notion that vv mRNAs were MT associated and that MT depletion severely affected viral (but not cellular) mRNA synthesis and stability. By confocal microscopy the viral mRNA structures appeared to be surrounded by molecules of the translation machinery, showing that they were active in protein synthesis. Finally, our data suggest a role for a MT and RNA-binding viral protein of 25 kDa (gene L4R), in mRNA targeting away from intracellular cores to their sites of cytoplasmic accumulation

Spectral theory of some non-selfadjoint linear differential operators

We give a characterisation of the spectral properties of linear differential operators with constant coefficients, acting on functions defined on a bounded interval, and determined by general linear boundary conditions. The boundary conditions may be such that the resulting operator is not selfadjoint. We associate the spectral properties of such an operator $S$ with the properties of the solution of a corresponding boundary value problem for the partial differential equation $\partial_t q \pm iSq=0$. Namely, we are able to establish an explicit correspondence between the properties of the family of eigenfunctions of the operator, and in particular whether this family is a basis, and the existence and properties of the unique solution of the associated boundary value problem. When such a unique solution exists, we consider its representation as a complex contour integral that is obtained using a transform method recently proposed by Fokas and one of the authors. The analyticity properties of the integrand in this representation are crucial for studying the spectral theory of the associated operator.Comment: 1 figur

The origins of intensive marine fishing in medieval Europe: the English evidence

The catastrophic impact of fishing pressure on species such as cod and herring is well documented. However, the antiquity of their intensive exploitation has not been established. Systematic catch statistics are only available for ca. 100 years, but large-scale fishing industries existed in medieval Europe and the expansion of cod fishing from the fourteenth century (first in Iceland, then in Newfoundland) played an important role in the European colonization of the Northwest Atlantic. History has demonstrated the scale of these late medieval and post-medieval fisheries, but only archaeology can illuminate earlier practices. Zooarchaeological evidence shows that the clearest changes in marine fishing in England between AD 600 and 1600 occurred rapidly around AD 1000 and involved large increases in catches of herring and cod. Surprisingly, this revolution predated the documented post-medieval expansion of England's sea fisheries and coincided with the Medieval Warm Period-when natural herring and cod productivity was probably low in the North Sea. This counterintuitive discovery can be explained by the concurrent rise of urbanism and human impacts on freshwater ecosystems. The search for 'pristine' baselines regarding marine ecosystems will thus need to employ medieval palaeoecological proxies in addition to recent fisheries data and early modern historical records

Randomised controlled trial and economic evaluation of a chest pain observation unit compared with routine care

Objectives To measure the effectiveness and cost effectiveness of providing care in a chest pain observation unit compared with routine care for patients with acute, undifferentiated chest pain. Design Cluster randomised controlled trial, with 442 days randomised to the chest pain observation unit or routine care, and cost effectiveness analysis from a health service costing perspective. Setting The emergency department at the Northern General Hospital, Sheffield, United Kingdom. Participants 972 patients with acute, undifferentiated chest pain (479 attending on days when care was delivered in the chest pain observation unit, 493 on days of routine care) followed up until six months after initial attendance. Main outcome measures The proportion of participants admitted to hospital, the proportion with acute coronary syndrome sent home inappropriately, major adverse cardiac events over six months, health utility, hospital reattendance and readmission, and costs per patient to the health service. Results Use of a chest pain observation unit reduced the proportion of patients admitted from 54% to 37% (difference 17%, odds ratio 0.50, 95% confidence interval 0.39 to 0.65, P < 0.001) and the proportion discharged with acute coronary syndrome from 14% to 6% (8%, –7% to 23%, P = 0.264). Rates of cardiac event were unchanged. Care in the chest pain observation unit was associated with improved health utility during follow up (0.0137 quality adjusted life years gained, 95% confidence interval 0.0030 to 0.0254, P = 0.022) and a saving of £78 per patient (–£56 to £210, P = 0.252). Conclusions Care in a chest pain observation unit can improve outcomes and may reduce costs to the health service. It seems to be more effective and more cost effective than routine care

Effect of Short Chain Branching on the Interlamellar Structure of Semicrystalline Polyethylene

We use molecular simulations with a united atom force field to examine the effect of short chain branching (SCB) on the noncrystalline, interlamellar structure typical of linear low density polyethylene (LLDPE). The model is predicated on a metastable thermodynamic equilibrium within the interlamellar space of the crystal stack and accounts explicitly for the various chain topologies (loops, tails, and bridges) therein. We examine three branched systems containing methyl, ethyl, and butyl side branches and compare our results to high density polyethylene (HDPE), without branches. We also compare results for two united atom force fields, PYS and TraPPE-UA, within the context of these simulations. In contrast to conventional wisdom, our simulations indicate that the thicknesses of the interfacial regions in systems with SCB are smaller than those observed for a linear polyethylene without branches and that branches are uniformly distributed throughout the interlamellar region. We find a prevalence of gauche states along the backbone due to the presence of branches and an abrupt decrease in the orientational order in the region immediately adjacent to the crystallite

Validity and reliability of the Oral Impacts on Daily Performance (OIDP) frequency scale: a cross-sectional study of adolescents in Uganda

BACKGROUND: Assessing oral health related quality of life impact of mouth in adolescents is a relatively ignored area in dental research. This study aimed to examine reliability and validity of an abbreviated version of the oral impact of daily performance (OIDP) questionnaire and to analyse the interrelationship among OIDP scores, socio-demographic characteristics and oral health status in Uganda. METHOD: 1146 adolescents (mean age 15.8, response rate 87%) attending secondary schools in Kampala (urban) and Lira (rural) completed a survey instrument designed to measure subjective oral health indicators including the eight-item OIDP frequency scores. A clinical examination was conducted among 372 students (mean age 16.3, response rate 72%) and caries was assessed following the World Health Organisation criteria (1997). RESULTS: 62% of the students experienced at least one oral impact during the 6 months preceding the survey. Cronbach's alpha for the OIDP frequency items was 0.91 and the corrected item-total correlation ranged from 0.62 to 0.75. Discriminant and construct validity were demonstrated in that the OIDP scores varied systematically in the expected direction with missing teeth and self-report indicators of oral health status, respectively. Socio-demographics and dental attendance did not predict OIDP through interaction with clinical indicators but varied systematically and independently with OIDP frequency scores in the multivariate analysis. CONCLUSION: the OIDP frequency score have acceptable psychometric properties in the context of an oral health survey among Ugandan adolescents. Some evidence of the importance of social and personal characteristics in shaping adolescents' responses to oral disorders was provided