Is endoluminal abdominal aortic aneurysm repair using an aortoaortic (tube) device a durable procedure?

BACKGROUND: Controversies over the frequency and intensity of the follow-up care of breast cancer patients exist. Some physicians have adopted an intensive approach to follow-up care that consists of frequent laboratory tests and routine imaging studies, including chest radiographs, bone scans, and CT scans, whereas others have established a minimalist approach consisting of only history, physical examinations, and mammograms. OBJECTIVES: Our objective was to evaluate the role of intensive follow-up on detection of breast cancer recurrence and to examine the impact of follow-up on overall survival. METHODS: During a 10-year period (1986-1996), 129 patients with recurrent disease were identified from a prospective database of 1898 breast cancer patients. The patients with recurrent disease were divided into minimalist or intensive groups according to method of detection. RESULTS: Twenty-seven of 126 (21%) patients were assigned to the intensive method of detection group (LFT, CEA, CA 15-3, chest radiograph, CT scan, and bone scan); 99 of 126 (79%) patients were assigned to the minimal detection group (history, physical examination, and mammography). Distant disease to the bone was the most common initial tumor recurrence, at 27%. History, physical examination, and mammography detected recurrent cancer in approximately the same amount of time as LFTs, tumor markers, CT scans, and chest radiographs (P = .960). When the recurrent patients were divided into intensive and minimalist groups and analyzed by time to detection of recurrence, there was no significant difference between the time to detection in those recurrences detected by intensive methods and those recurrences detected by minimalist methods (P = .95). The independent variables age, tumor size, type of surgery, number of positive nodes, time to recurrence, method of detection, and site of recurrence (regional or distant) were subject to univariate and multivariate analysis by the Cox proportional hazards model. Only two variables had an impact on survival by multivariate analysis: early timing of the recurrence (P = .0011) and the site of the recurrence (P = .02). Timing was defined as early (< or =365 days from the time of diagnosis to recurrence) or late (> or =365 days from the time of diagnosis to recurrence). Early recurrence was the first variable found to be significant on stepwise forward regression analysis. The primary site of recurrence was significant at step two. The method of detection--intensive or minimal--did not significantly affect survival (P = .18). CONCLUSIONS: There is no survival benefit to routine intensive follow-up regimens in detecting recurrent breast cancer. Expensive diagnostic tests such as bone scans, CT scans, and serial tumor markers are best used for detection of metastasis in symptomatic patients.     

A survey and classification of hypertext documentation systems

The authors describe and classify different hypertext documentation approaches by surveying a number of existing systems. They comprehensively list features of each system but do not numerically compare systems because of the subjective nature of evaluation. Instead, the data provided should be used as a basis for local comparisons by the reader. The classification breaks systems down according to publishing type, i.e. those designed for both publishing and accessing hypertext, either publishing or accessing documentation, and those that use general-purpose hypertext systems for document production and presentation. These categories are further subdivided according to functionality and specific system information     

Simple and accurate methods for quantifying deformation,disruption, and development in biological tissues

When mechanical factors underlie growth, development, disease or healing, they often function through local regions of tissue where deformation is highly concentrated. Current optical techniques to estimate deformation can lack precision and accuracy in such regions due to challenges in distinguishing a region of concentrated deformation from an error in displacement tracking. Here, we present a simple and general technique for improving the accuracy and precision of strain estimation and an associated technique for distinguishing a concentrated deformation from a tracking error. The strain estimation technique improves accuracy relative to other state-of-the-art algorithms by directly estimating strain fields without first estimating displacements, resulting in a very simple method and low computational cost. The technique for identifying local elevation of strain enables for the first time the successful identification of the onset and consequences of local strain concentrating features such as cracks and tears in a highly strained tissue. We apply these new techniques to demonstrate a novel hypothesis in prenatal wound healing. More generally, the analytical methods we have developed provide a simple tool for quantifying the appearance and magnitude of localized deformation from a series of digital images across a broad range of disciplines.     

Limit and shakedown analysis of nozzle/cylinder intersections under internal pressure and in-plane moment loading

A simple technique called the elastic compensation method developed previously by Mackenzie & Boyle is used in combination with full three-dimensional finite-element analysis to obtain limit and shakedown interaction diagrams for nozzle/cylinder intersections subject to combined internal pressure and in-plane nozzle moment loading. The results are compared with solutions from the literature and also with detailed elasto-plastic thin shell finite-element analysis. It is found that the simple elastic compensation procedure can provide good estimates of plastic failure mechanisms for complex three-dimensional structures. A detailed discussion of various issues which arose relates to finite-element modelling and the measures taken to improve the results are also documented.     

Surveillance of developmental disabilities with an emphasis on special studies

The developing central nervous system seems to be particularly vulnerable to chemical insults. A model for developmental disabilities surveillance is presented that provides a reasonable framework for monitoring the prevalence of various developmental abnormalities in human populations. Effective monitoring will not only increase the likelihood of detecting the adverse effects of new physical or chemical agents in the environment but will provide a readily available case series for specially directed case-control studies. A specific example is provided of a large case-control study of cerebral palsy and intrapartum magnesium exposure among very low birth weight children, which is being conducted within the framework of a developmental disabilities surveillance program.     

Finger-like projections of plasma membrane in the most senescent fiber cells of human lenses

PURPOSE: To corroborate the findings of finger-like membrane projections in monkey and baboon lenses, in human lens fiber cells. METHODS: Normal human lenses, two months to 76 years old, as well as age-related nuclear cataracts, were immersion fixed in 2% paraformaldehyde-0.2% glutaraldehyde in 0.1 M sodium cacodylate buffer pH 7.2 for 24 h at room temperature, cut into 200-500 microm thick sections along the equatorial axis, fixed for an additional 12-18 h at room temperature, dehydrated in an ascending ethanol series and embedded in Lowicryl K4M. Semi-thick sections (0.25-1.0 microm) were cut, absorbed onto 75 or 100 nickel slotted grids, labeled with anti-MIP 26 or phalloidin, stained with 2% uranyl acetate and viewed by transmission electron microscopy at 100 kV. RESULTS: Transmission electron microscopy micrographs demonstrated the presence of finger-like plasma membrane projections measuring 0.16-0.25 microm in diameter and 1.0-6.5 microm in length with bulbous terminal tips in the most senescent fiber cells in two-month and older normal lenses, as well as, in nuclear cataracts. These projections appeared to overlie furrowed membrane domains in the extracellular space, as well as project into the cytosol along the cytosolic leaflet of plasma membrane. CONCLUSIONS: The results extend the findings in monkey and baboon lenses, to the human lens, and demonstrate that these projections, which sparsely label with antiserum against MIP 26, but not filamentous actin, not only extend into the extracellular space, but also project inward into the cytosol.     

Enhanced responses to a DNA vaccine encoding a fusion antigen that is directed to sites of immune induction

Viral infection and vaccination with DNA both induce similar immune responses to encoded antigens that are produced by the host. The availability of antigens in lymphoid organs is important in generating an immune response to viral challenge. Antigen availability may also be important in the response to DNA vaccines, because immune responses are stronger when antigen is secreted from DNA-transfected cells. We directed antigen to lymphoid organs by vaccination with DNA encoding antigen-ligand fusion proteins. The two ligands examined bind to receptors that are present on high endothelial venule cells of lymph nodes or on antigen-presenting cells. Here we show that both the humoral and the cellular immune responses to a model DNA vaccine were enhanced using either antigen-targeting strategy. Moreover, directing antigen to antigen-presenting cells speeded up, and altered the form of, the immune response. Directing antigen to sites of immune-response induction may represent a generic means of tailoring a potent and effective immune response to a DNA vaccine.     

osteoprotegerin-deficient mice develop early onset osteoporosis and arterial calcification

Osteoprotegerin (OPG) is a secreted protein that inhibits osteoclast formation. In this study the physiological role of OPG is investigated by generating OPG-deficient mice. Adolescent and adult OPG-/- mice exhibit a decrease in total bone density characterized by severe trabecular and cortical bone porosity, marked thinning of the parietal bones of the skull, and a high incidence of fractures. These findings demonstrate that OPG is a critical regulator of postnatal bone mass. Unexpectedly, OPG-deficient mice also exhibit medial calcification of the aorta and renal arteries, suggesting that regulation of OPG, its signaling pathway, or its ligand(s) may play a role in the long observed association between osteoporosis and vascular calcification.     

Geographical variation in the referral of patients with chronic end stage renal failure for renal replacement therapy

The translocation of t(8;16)(p11;p13) has been demonstrated in the blasts of a phenotypically normal newborn baby with acute monoblastic leukemia. No antileukemic therapy was administered and spontaneous, complete remission was observed at 2 months of age. The patient remains well 18 months after the diagnosis and continues to have a normal hemogram.     

Strategies to manipulate reliability: impact on statistical associations

OBJECTIVE: To examine the effects of improving measurement reliability on associations between risk factors and childhood psychiatric disorder. METHOD: Data were from a general population sample of parents (N = 211) with children aged 6 to 16 years. Reliability of measurement was improved in three ways: by increasing the number of items in a scale (internal-consistency reliability), by averaging assessments of the same variables collected on two different occasions, and by constructing latent variable measures. To assess the effects of improving reliability, selected risk factors were regressed on parental assessments of childhood oppositional defiant disorder (ODD) and overanxious disorder (OAD). RESULTS: Improving reliability led to systematic increases in the magnitude of standardized regression coefficients between family dysfunction and ODD (beta = .30-.51) and between family dysfunction and OAD (beta = .24-.48). In multiple regression, improving reliability served to strengthen the specificity of associations between ODD, OAD, and family dysfunction and maternal depressed mood. Although latent variable methods produced the largest associations, the standard errors of these estimates were also larger, resulting in wider confidence intervals and slightly larger significance values. CONCLUSIONS: Improving reliability of measurement results in larger associations between risk factors and childhood disorder and may increase the opportunity of revealing differential associations between variables.