Northwestern University

About: Northwestern University is a education organization based out in Evanston, Illinois, United States. It is known for research contribution in the topics: Population & Transplantation. The organization has 75430 authors who have published 188857 publications receiving 9463252 citations. The organization is also known as: Northwestern & NU.

Deterministic Equivalents for Optimizing and Satisficing under Chance Constraints

Abstract: Chance constrained programming admits random data variations and permits constraint violations up to specified probability limits. Different kinds of decision rules and optimizing objectives may be used so that, under certain conditions, a programming problem not necessarily linear can be achieved that is deterministic---in that all random elements have been eliminated. Existence of such “deterministic equivalents” in the form of specified convex programming problems is here established for a general class of linear decision rules under the following 3 classes of objectives 1 maximum expected value “E model”, 2 minimum variance “V model”, and 3 maximum probability “P model”. Various explanations and interpretations of these results are supplied along with other aspects of chance constrained programming. For example, the “P model” is interpreted so that H. A. Simon's suggestions for “satisficing” can be studied relative to more traditional optimizing objectives associated with “E” and “V model” variants.

Multiple Chronic Conditions: Prevalence, Health Consequences, and Implications for Quality, Care Management, and Costs

Abstract: Persons with multiple chronic conditions are a large and growing segment of the US population. However, little is known about how chronic conditions cluster, and the ramifications of having specific combinations of chronic conditions. Clinical guidelines and disease management programs focus on single conditions, and clinical research often excludes persons with multiple chronic conditions. Understanding how conditions in combination impact the burden of disease and the costs and quality of care received is critical to improving care for the 1 in 5 Americans with multiple chronic conditions. This Medline review of publications examining somatic chronic conditions co-occurring with 1 or more additional specific chronic illness between January 2000 and March 2007 summarizes the state of our understanding of the prevalence and health challenges of multiple chronic conditions and the implications for quality, care management, and costs.

Multi-step pericellular proteolysis controls the transition from individual to collective cancer cell invasion

Abstract: Invasive cell migration through tissue barriers requires pericellular remodelling of extracellular matrix (ECM) executed by cell-surface proteases, particularly membrane-type-1 matrix metalloproteinase (MT1-MMP/MMP-14). Using time-resolved multimodal microscopy, we show how invasive HT-1080 fibrosarcoma and MDA-MB-231 breast cancer cells coordinate mechanotransduction and fibrillar collagen remodelling by segregating the anterior force-generating leading edge containing beta1 integrin, MT1-MMP and F-actin from a posterior proteolytic zone executing fibre breakdown. During forward movement, sterically impeding fibres are selectively realigned into microtracks of single-cell calibre. Microtracks become expanded by multiple following cells by means of the large-scale degradation of lateral ECM interfaces, ultimately prompting transition towards collective invasion similar to that in vivo. Both ECM track widening and transition to multicellular invasion are dependent on MT1-MMP-mediated collagenolysis, shown by broad-spectrum protease inhibition and RNA interference. Thus, invasive migration and proteolytic ECM remodelling are interdependent processes that control tissue micropatterning and macropatterning and, consequently, individual and collective cell migration.

Major Risk Factors as Antecedents of Fatal and Nonfatal Coronary Heart Disease Events

Abstract: ContextA frequently cited concept is that individual major risk factors for coronary heart disease (CHD) are absent in many patients (perhaps >50%) with CHD. However, prior studies have not systematically evaluated the extent to which CHD patients have previous exposure to at least 1 risk factor, including diabetes, cigarette smoking, or clinically elevated levels of cholesterol or blood pressure.ObjectiveTo determine the frequency of exposure to major CHD risk factors.Design, Setting, and ParticipantsThree prospective cohort studies were included: the Chicago Heart Association Detection Project in Industry, with a population sample of 35 642 employed men and women aged 18 to 59 years; screenees for the Multiple Risk Factor Intervention Trial, including 347 978 men aged 35 to 57 years; and a population-based sample of 3295 men and women aged 34 to 59 years from the Framingham Heart Study (FHS). Follow-up lasted 21 to 30 years across the studies.Main Outcome MeasuresFatal CHD in all cohorts and nonfatal myocardial infarction (MI) in the FHS, compared by exposure to major CHD risk factors, defined as total cholesterol of at least 240 mg/dL (≥6.22 mmol/L), systolic blood pressure of at least 140 mm Hg, diastolic blood pressure of at least 90 mm Hg, cigarette smoking, and diabetes. Participants were stratified by sex and age (18-39 vs 40-59 years).ResultsFor fatal CHD (n = 20 995), exposure to at least 1 clinically elevated major risk factor ranged from 87% to 100%. Among those aged 40 to 59 years at baseline with fatal CHD (n = 19 263), exposure to at least 1 major risk factor ranged from 87% to 94%. For nonfatal MI, prior exposure was documented in 92% (95% CI, 87%-96%) (n = 167) of men aged 40 to 59 years at baseline and in 87% (95% CI, 80%-94%) (n = 94) of women in this age group.ConclusionsAntecedent major CHD risk factor exposures were very common among those who developed CHD, emphasizing the importance of considering all major risk factors in determining CHD risk estimation and in attempting to prevent clinical CHD. These results challenge claims that CHD events commonly occur in persons without exposure to at least 1 major CHD risk factor.