Title

Professor and Chair

Education

Ph.D., Chemical Engineering – Rice University, 1995
B.S., Chemical Engineering – Purdue University, 1990

Professional Interests

Microbial Adhesion and Biofilm Formation. My research interests involve the application of chemical engineering principles to solve questions concerning the molecular mechanisms of cell adhesion processes. Our approach uses controlled, dynamic, /in vitro/ experimental systems to systematically and comprehensively examine cell adhesion phenomena. The ultimate goal is to identify and understand the molecular mechanisms involved in cell adhesion in order to manipulate either cells or surfaces to increase or prevent adhesion as desired.

Bacterial adherence to host tissues is the crucial first step in the development of many bacterial infections. The adhesion of bacteria is predominantly dependent on specific interactions between cell surface receptors and ligands in the host tissue. Both gram-negative and gram-positive bacteria, as well as yeast cells, have been shown to bind extracellular matrix proteins with a high degree of specificity and affinity. These interactions have been proposed to mediate microbial adherence to host tissues where the tissue location of the matrix protein may impose tissue specificity of the infection. In many cases, /in vivo/ microbial adherence occurs under shear conditions in the cardiovascular system. Consequently, the molecular surface characteristics of the bacteria and tissue (or biomaterial) will govern the probability of an adhesive interaction, while the local hemodynamics will determine the kinetics of the process.

/Staphylococcus/ /aureus/ is involved in many different types of infections, a number of which occur in the cardiovascular system (e.g. vascular graft infection, endocarditis). The heavy use of antibiotics in treating /S. aureus/ infections has led to a rapid rise in antibiotic resistance, and strains resistant to vancomycin (the “antibiotic of last resort”) have recently emerged. Therefore, novel strategies to combat staphylococcal infections are becoming increasingly important.

/S aureus/ pathogenesis typically begins with adhesion to either host tissue or protein-coated biomaterial, which can eventually lead to tissue colonization, biofilm formation and metastatic seeding through the bloodstream to other sites by planktonic (suspended) cells. Once a biofilm has developed, the ability of the host’s immune system to combat the infection is greatly reduced and antibiotic treatment becomes dramatically less effective. Chronic infection is often the result.
While it is commonly known that bacteria growing as a biofilm are phenotypically different than planktonic cells, a fundamental and comprehensive understanding of how the phenotypes differ in staphylococci is lacking.

The broad objective of our research is to comprehensively characterize the molecular interactions between /S. aureus /and tissue/blood components as a function of the dynamic shear environment in order to provide a rational basis for the development of novel treatments to combat cardiovascular staphylococcal infections. In addition, we seek to characterize the structure, growth and maturation of /S. aureus/ biofilms as well as the phenotypic similarities and differences between staphylococci grown as biofilm versus planktonic cells. Elucidation of these phenotypic differences may ultimately lead to the design of novel therapeutic strategies for staphylococcal biofilm prevention and control. A long-term goal of our work is to investigate the interrelationship between thrombogenesis (blood clot formation) and cardiovascular infection mechanisms.

Engineering Education. The need to recruit more students into engineering fields in the U.S. is urgent. Although increased employment opportunities for engineering careers are forecast for the future, national enrollment in engineering disciplines has been declining. These diverging trends are likely to create a shortfall of trained engineers in the U.S. in the near future. While women and minorities comprise an increasingly large percentage of the total workforce, representation in engineering careers remains low at nine and four percent respectively.

In order to alter current enrollment trends, more students must be attracted to engineering careers and be prepared to pursue engineering study at the college level. Increasing the desire among women and minorities to pursue degrees in engineering will be critical.

To meet these challenges, new innovative high school curricula are needed. Indeed, the recent report entitled “Rising Above the Gathering Storm” issued by the National Academy of Sciences, National Academy of Engineering, and Institute of Medicine highlighted the need to develop rigorous new K-12 curriculum materials in science and mathematics as a highest priority action. New curricula must be accessible to all high schools and must inspire greater numbers of women and minorities to choose engineering careers. The *INSPIRES* Curriculum is being developed with these goals in mind.

The *INSPIRES* Curriculum (*IN*creasing *S*tudent *P*articipation, *I*nterest and *R*ecruitment in *E*ngineering and *S*cience) is the result of a National Science Foundation funded project to provide new curricula for high school technology education. The curriculum uses engineering design challenges and problem-based learning strategies to increase technology literacy as defined by the International Technology Education Association. *INSPIRES* targets national standards for technology education that relate to engineering design as well as key skills that we believe are foundational for success in the study of engineering. The *INSPIRES* Curriculum will ultimately consist of five stand-alone inquiry-based learning modules, each targeting a unique societal need or problem.

Publications

George, NPE, Konstantopoulos, K, and Ross, JM. Differential kinetics and molecular recognition mechanisms involved in early versus late growth phase S. aureus cell binding to platelets under physiological shear conditions. J Infect Dis, 196:639-46, 2007. [PMID: 17624852]

Ymele-Leki, P, and Ross, JM. Erosion from Staphylococcus aureus biofilms grown under physiologically relevant fluid shear yields bacterial cells with reduced avidity to collagen. Appl Env Microbiol, 73:1834-41, 2007. [PMID: 17277217]

George, NPE, Shin, PK, Wei, Q, Konstantopoulos, K, and Ross, JM.
Staphylococcus aureus adhesion via Spa, ClfA and SdrCDE to immobilized platelets demonstrates shear dependent behavior. Arterioscler Thromb Vasc Biol, 26:2394-2400, 2006. [PMID: 16857949]

Shin, PK, Pawar, P, Konstantopoulos, K, and Ross, JM. Characteristics of a new Staphylococcus aureus-RBC adhesion mechanism independent of fibrinogen and immunoglobulin G under hydrodynamic shear conditions. Am J Physiol Cell Physiol, 289:C727-34, 2005. [PMID: 15888554]

Nandakumar, R, Madayiputhiya, N, Marten, MR, and Ross, JM. Proteome analysis of cell wall associated proteins from Staphylococcus aureus: Lysis and sample preparation protocols. J Proteome Res, 4:250-7, 2005. [PMID: 15822900]

Pawar, P, Shin, PK, Ross, JM, and Konstantopoulos, K. Fluid shear regulates the kinetics and receptor specificity of Staphylococcus aureus binding to activated platelets. J Immunol, 173: 1258-65, 2004. [PMID: 15240718]

Mascari, L, and Ross, JM. Quantification of staphylococcal-collagen binding interactions in whole blood using a confocal microscopy shear adhesion assay. J Infect Dis, 188:98-107, 2003. [PMID: 12825177]

Mascari, L, Ymele-Leki, P, Speziale, P, Eggleton, CD, and Ross, JM. Fluid shear contributions to cell detachment initiated by a monoclonal antibody. Biotechnol Bioeng, 85: 56-74, 2003. [PMID: 12740934]

Mascari, L, and Ross, JM. Quantifying the temporal expression of the /Staphylococcus aureus/ collagen adhesin. /Microb. Pathog/., *32*:99-103, 2002. [PMID: 11812215]

Mascari, L, and Ross, JM. Hydrodynamic shear and collagen receptor density determine the adhesion capacity of S. aureus to collagen. Ann Biomed Eng, 29:956-62, 2001. [PMID: 11791678]