Robust estimation of bacterial cell count from optical density

Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data

Corporate Political Activism Crises Response and Attachment Styles

This dissertation investigates how consumers' attachment styles affect their responses to corporate political activism stands. Traditionally, businesses have shied away from politics, except when lobbying for more favorable business policies. But in the past few years, many companies have moved beyond lobbying and have gotten involved in or have been pulled into controversial social and political issues, which often pit different segments of society against each other. Examples of corporate political activism (CPA) include the stands taken by Apple on gay marriage, Starbucks on Immigration, and NCAA on LGBT rights. Given the contentious nature of such issues, these companies have faced a backlash from consumers that hold contrary views. Such crises, related to a company's political activities, are becoming common and can lead to severe deterioration of customer relationships with a company. Handling CPA crises in a manner that minimizes damage to these relationships is of critical importance. Given that a company has no option but to upset some customers when responding to CPA crises, knowing which customers are more likely to excuse its actions is of great value as it enables the company to minimize crises damage by accommodating customers that are less forgiving. In this dissertation, I employ attachment theory to develop response strategies that can be used in case of CPA crises. Attachment theory is particularly useful in predicting consumer response to CPA crises as it can (a) help identify consumers who are more likely to continue their relationship with the company despite CPA related transgressions (e.g. taking an opposing stand), and (b) guide the development post-crisis communication strategies that improve the chances of appeasing disgruntled consumers (e.g. message frames). Study 1 investigates the impact of consumers' attachment styles on their response to a company's decision to reverse its original stand on the issue of gun control. As predicted, results show that avoidant consumers have greater purchase intention than anxious consumers when the company changes its stand even when the change aligns with their own stand on gun-control. Study 2 shows that the effect of a company's decision to reverse its original stand or stand by it on consumers' purchase intent is mediated by the perceived responsiveness of the company. Avoidant consumers are more likely to perceive a company to be responsive when it doubles down on its original stand even when it is opposite to their own views on the issue. Study 3 explores the use of dependent versus independent message frames to communicate a company's decision to reverse its stand to minimize the negative impact on perceived responsiveness for avoidant consumers.Ph.D., Business Administration -- Drexel University, 201

SUCCESSFUL USE OF POLYURETHANE COVERED CORONARY STENT (PCCS) FOR MANAGEMENT OF GIANT CORONARY ANEURYSM

Background: Coronary Artery Aneurysm (CAA) is defined as localized dilatation of coronary artery exceeding 50% of its reference diameter. Although CAA is uncommon, it is associated with a poor prognosis. At present, there are no guidelines on its management. By presenting this case, we acknowledge the scarcity of data on this topic and support the use of PCCS for clinical situations that may mimic our case. Case: 71 year old female with multiple comorbidities presented with NSTEMI. Coronary angiogram showed 95% stenosis of proximal RCA with a large aneurysm distal to the stenotic segment. Due to multiple comorbidities, patient was deemed a poor surgical candidate. Thereafter, a staged PCI of proximal RCA and simultaneous repair of coronary aneurysm using a single covered coronary stent was planned. A 4mm x 26mm PCCS was deployed successfully. At 6-month follow-up, the patient had no major adverse cardiovascular event. Decision-making: PCCS were originally approved to treat coronary perforations. Data on its use in treating CAA is not sufficient. Our patient had prohibitive surgical risk. Clinical presentation was complicated with the presence of a large aneurysm in conjunction with significant subtotal stenosis. We decided to intervene percutaneously and fix both lesions simultaneously. Conclusion: Giant CAA although occurs infrequently, it may have dreaded complications like rupture and death. PCCS could potentially be used to seal-off CAA, if hemodynamically indicated in a poor surgical candidate

Evaluation of tuberculosis-associated chronic obstructive pulmonary disease at a tertiary care hospital: A case–control study

Context: Irreversible airway obstruction is important sequelae of pulmonary tuberculosis (TB) that might contribute to a significant proportion of chronic obstructive pulmonary disease (COPD). India has the highest TB burden in the world. However, there are limited data on the prevalence and presentation of TB-associated COPD from this region. Aims: This study aims to evaluate the prevalence of TB-associated COPD among COPD patients presenting to a tertiary care hospital. Settings and Design: It was a case–control study conducted in a tertiary care hospital. Subjects and Methods: Stable COPD patients presenting to chest OPD and an equal number of healthy controls were enrolled. COPD patients were subjected to detailed clinical evaluation and lung function test. History of pulmonary TB was evaluated from both groups through self-reporting and/or checking previous records. TB-associated COPD patients were identified and their prevalence and distinguishing features evaluated. Results: Of 74 COPD patients, 24 (32.4%) had previous history of pulmonary TB. The odds of having a previous TB in COPD patients was 3.96 (95% confidence interval: 1.64–9.55; P = 0.002) as compared to controls. Patients with TB-associated COPD were younger (P = 0.02), had lesser pack-years of smoking (P = 0.027) but had more number of hospitalizations (P = 0.01). The airflow limitation was similar in both groups. Conclusions: TB-associated COPD constitutes a significant proportion of COPD patients. It is a distinct clinical entity with preponderance in young. It may be associated with frequent hospitalizations as compared to other COPD patients