Multicenter investigation of coronary stenting to treat acute or threatened closure after percutaneous transluminal coronary angioplasty: clinical and angiographic outcomes

OBJECTIVES: This study reports on the initial experience with the Gianturco-Roubin flexible coronary stent. The immediate and 6-month efficacy of the device and the incidence of the complications of death, myocardial infarction, emergency coronary artery bypass surgery and recurrent ischemic events are presented. BACKGROUND: Abrupt or threatened vessel closure after coronary angioplasty is associated with increased risk of myocardial infarction, emergency coronary artery bypass graft surgery and in-hospital death. When dissection or prolapse of dilated plaque into the lumen is unresponsive to additional or prolonged balloon catheter inflation, coronary stenting offers a nonsurgical mechanical means to rapidly restore stable vessel geometry and adequate coronary blood flow. METHODS: From September 1988 through June 1991, 518 patients underwent attempted coronary stenting with the 20-mm long Gianturco-Roubin coronary stent for acute or threatened vessel closure after angioplasty. In 494 patients, one or more stents were deployed. Thirty-two percent of patients received stents for acute closure and 69% for threatened closure. RESULTS: Successful deployment was achieved in 95.4% of patients. Overall, stenting resulted in an immediate angiographic improvement in the diameter stenosis from 63 +/- 25% before stenting to 15 +/- 14% after stenting. Emergency coronary artery bypass graft surgery was required in 4.3% (21 of 493 patients). The incidence of in-hospital myocardial infarction (Q wave and non-Q wave) was 5.5% (27 of 493 patients). At 6 months, myocardial infarction was infrequent, occurring in 1.6% (8 of 493 patients). The incidence of in-hospital death was 2.2% (11 of 493 patients). Late death occurred in 7 patients (1.4%) and 34 patients (6.9%) required later bypass graft surgery. Complications included blood loss, primarily from the arterial access site, and subacute thrombosis of the stented vessel in 43 patients (8.7%). CONCLUSIONS: The early multicenter experience suggests that this stent is a useful adjunct to coronary angioplasty to prevent or minimize complications associated with flow-limiting coronary artery dissections previously correctable only by surgery. Although this study was not randomized, it demonstrated a high technical success rate and encouraging results with respect to the low incidence of emergency coronary artery bypass graft surgery and myocardial infarction.     

Multivariate analysis of risk factors in stage 4 neuroblastoma patients over the age of one year treated with megatherapy and stem-cell transplantation: a report from the European Bone Marrow Transplantation Solid Tumor Registry

PURPOSE: The European Bone Marrow Transplantation (EBMT) Solid Tumor Registry (STR) contains detailed information on children with advanced neuroblastoma who, after standard-dose induction chemotherapy and surgery, received myeloablative megatherapy (MGT) followed by stem-cell transplantation (SCT). This data base was analyzed to identify factors that predict event-free survival (EFS). PATIENTS AND METHODS: Eligibility criteria were stage IV neuroblastoma, age over 1 year at diagnosis, and no relapse before MGT/SCT. Between February 1978 and July 1992, 549 patients were registered by 36 European transplant centers. The median age at diagnosis was 36 months (range, 13 to 216 months) and the male-female ratio was 1:45. Before MGT, 157 patients were in complete remission (CR), 156 in very good partial remission (VGPR), and 208 in partial remission (PR), whereas 24 had had only a minor response (MR). One hundred ten of 546 patients had undergone two successive MGT procedures. The median observation time was 60 months (range, 12 to 187 months). RESULTS: Actuarial EFS is 26% at 5 years. Multivariate analysis by the Cox proportional hazards regression model included 529 patients with complete data sets. After adjustment for treatment duration before MGT and double MGT procedures, two adverse, independent risk factors that influenced EFS were identified: (1) persisting skeletal lesions before MGT as defined by technetium (99TC) scans and/or meta-iodobenzylguanidine (mIBG) scans (P = .004) and (2) persisting bone marrow involvement before MGT (P = .03). CONCLUSION: After induction treatment, persisting skeletal disease as defined above and persisting bone marrow involvement may be predictive of a particularly poor outcome. Physicians may consider this an additional important tool to decide the patient's management.     

Decomposition kinetics of lithium amide for hydrogen storage materials

The kinetic behavior of LiNH₂ decomposition by ammonia release was quantified using thermogravimetric analysis (TGA). While not itself a hydrogen storage material, LiNH₂ is a primary component of the hydrided state in Li–N–H storage materials based on Li₃N or Li₂NH. Its decomposition by ammonia release, and consequent degradation of the hydrogen storage capacity, has important implications for the durability of Li–N–H storage systems. LiNH₂ from two commercial lots and one batch prepared at GM R&D were ball milled for 10 or 20 min to obtain fine LiNH₂ powders. Kinetic parameters were extracted from sets of TGA weight loss curves taken at different heating rates. The activation energy for the decomposition reaction was determined to be about 128 kJ/mole, virtually independent of the source and purity of the LiNH₂, its stoichiometry, ball milling time, and TGA sample size. The reaction rate was found to depend on the sample size as a consequence of the very low NH₃–LiNH₂ equilibrium vapor pressure at temperatures below 300 °C. Larger samples produce a local concentration of NH₃ high enough to inhibit further reaction. Direct isothermal measurements of the initial reaction rates at temperatures between 200 and 300 °C agree well with the values calculated from the heating rate-derived kinetic parameters. The durability of Li–N–H for hydrogen storage was estimated from the measured kinetic parameters by calculating the time required to decompose 20% of the initial LiNH₂, as a function of the operating temperature. The predicted lifetime falls below 10⁵ min for operating temperatures in excess of 160 °C.     

Laser surface modification using Inconel 617 machining swarf as coating material

A single-stage, blown powder laser cladding process is used to deposit a protective layer of Ni-based alloy Inconel 617 on mild steel substrates. A Design of Experiments methodology is used to analyse the effects of the major laser cladding processing parameters on the deposited layer characteristics. Layer thickness, microstructure, dilution, elemental composition and corrosion resistance are analysed and correlated with the processing parameters and the overall effectiveness of the protective coating assessed. The work is different in that the protective material, usually in the form of costly powder, is in this case virtually cost-free and simply recycled from machining waste without any costly atomisation or similar process. The results show a number of significant relationships between the processing parameters and the effectiveness of the protective coating. The layer thickness and hardness were found to increase with the mass feed rate and decrease with an increase in laser power. A mainly columnar dendritic microstructure was observed in the clads. There was no evidence of significant bonding defects, trapped unmelted particles or porosity under most conditions. In all samples, the coatings displayed significant higher corrosion resistance than the mild steel sample.     

Cost-effectiveness of HIV-prevention skills training for men who have sex with men

OBJECTIVE: A previous study empirically compared the effects of two HIV-prevention interventions for men who have sex with men: (i) a safer sex lecture, and (ii) the same lecture coupled with a 1.5 h skills-training group session. The skills-training intervention led to a significant increase in condom use at 12-month follow-up, compared with the lecture-only condition. The current study retrospectively assesses the incremental cost-effectiveness of skills training to determine whether it is worth the extra cost to add this component to an HIV-prevention intervention that would otherwise consist of a safer sex lecture only. DESIGN: Standard techniques of incremental cost-utility analysis were employed. METHODS: A societal perspective and a 5% discount rate were used. Cost categories assessed included: staff salary, fringe benefits, quality assurance, session materials, client transportation, client time valuation, and costs shared with other programs. A Bernoulli-process model of HIV transmission was used to estimate the number of HIV infections averted by the skills-training intervention component. For each infection averted, the discounted medical costs and quality-adjusted life years (QALY) saved were estimated. One- and multi-way sensitivity analyses were performed to assess the robustness of base-case results to changes in modeling assumptions. RESULTS: Under base-case assumptions, the incremental cost of the skills training was less than $13,000 (or about $40 per person). The discounted medical costs averted by incrementally preventing HIV infections were over $170,000; more than 21 discounted QALY were saved. The cost per QALY saved was negative, indicating cost-savings. These results are robust to changes in most modeling assumptions. However, the model is moderately sensitive to changes in the per-contact risk of HIV transmission. CONCLUSIONS: Under most reasonable assumptions, the incremental costs of the skills training were outweighed by the medical costs saved. Thus, not only is skills training effective in reducing risky behavior, it is also cost-saving.     

Cyberguide: A mobile context‐aware tour guide

Future computing environments will free the user from the constraints of the desktop. Applications for a mobile environment should take advantage of contextual information, such as position, to offer greater services to the user. In this paper, we present the Cyberguide project, in which we are building prototypes of a mobile context‐aware tour guide. Knowledge of the user's current location, as well as a history of past locations, are used to provide more of the kind of services that we come to expect from a real tour guide. We describe the architecture and features of a variety of Cyberguide prototypes developed for indoor and outdoor use on a number of different hand‐held platforms. We also discuss the general research issues that have emerged in our context‐aware applications development in a mobile environment. This revised version was published online in June 2006 with corrections to the Cover Date.     

A prospective randomized single-blind comparative trial of nafarelin acetate with buserelin in long-protocol gonadotrophin-releasing hormone analogue controlled in-vitro fertilization cycles

Matrix metalloproteinases (MMPs) play key roles in tissue remodeling during physiological and pathological processes by degrading various extracellular matrix (ECM) components. Although nine distinct MMPs have been characterized by cDNA cloning, there are thought to be more corresponding to the complexity of the ECM. MMP genes expressed in human tissues and cell lines were analyzed by the polymerase chain reaction (PCR) using degenerate primers that corresponded to the conserved amino acid (aa) sequences of the MMPs. One isolated complementary DNA (cDNA) fragment had sequence homology to the reported MMPs, but was otherwise unique. A human placenta cDNA library (Clontech) was screened using the fragment as a probe and a 3.4-kb cDNA fragment containing a long open reading frame (potentially encoding 582 aa) was isolated. The putative gene product had a common domain structure and the conserved sequence of a MMP, but it had a unique transmembrane (TM)-like structure at the C terminus. It should, therefore, be an TM protein, whereas all the other reported MMPs are secretory proteins. Thus, the gene is thought to be the first of a new subclass of MMPs whose products are potentially expressed on the cell surface.     

Volume-reduction technique for the X-ray spectrographic determination of micronutrients in plant tissues

A volume-reduction technique is described for the X-ray spectrographic analysis of the micronutrient elements manganese, iron, and zinc in plant tissues. This simple technique is believed to minimise inter-element effects and utilises dilution by volume instead of by weight, thus avoiding intimate mixing of sample and diluent. The method has particular advantages for the analysis of manganese and iron when they occur in plant tissues in concentrations large enough for inter-element effects to be serious.