Publications by authors named "Philip Keegan"

The intestinal epithelium comprises diverse cell types and executes many specialized functions as the primary interface between luminal contents and internal organs. A key function provided by the epithelium is maintenance of a barrier that protects the individual from pathogens, irritating luminal contents, and the microbiota. Disruption of this barrier can lead to inflammatory disease within the intestinal mucosa, and, in more severe cases, to sepsis.

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Penile cancer is a rare but debilitating condition, which often requires aggressive treatment. Partial penectomy is considered as a treatment option when a sufficient portion of the penile shaft can be maintained to preserve functionality. This systematic review, which followed the PRIMSA guidelines, aimed to evaluate the effects of partial penectomy for penile cancer on sexual function-the maintenance of which is often a priority in patient groups-and to identify potential factors which may moderate these effects.

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Microphysiological organ-on-chip models offer the potential to improve the prediction of drug safety and efficacy through recapitulation of human physiological responses. The importance of including multiple cell types within tissue models has been well documented. However, the study of cell interactions in vitro can be limited by complexity of the tissue model and throughput of current culture systems.

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Correction for 'A high-throughput microfluidic microphysiological system (PREDICT-96) to recapitulate hepatocyte function in dynamic, re-circulating flow conditions' by Kelly Tan et al., Lab Chip, 2019, 19, 1556-1566, DOI: .

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Objective: Sickle cell anemia (SCA) causes chronic inflammation and multiorgan damage. Less understood are the arterial complications, most evident by increased strokes among children. Proteolytic mechanisms, biomechanical consequences, and pharmaceutical inhibitory strategies were studied in a mouse model to provide a platform for mechanistic and intervention studies of large artery damage due to sickle cell disease.

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Hepatic in vitro platforms ranging from multi-well cultures to bioreactors and microscale systems have been developed as tools to recapitulate cellular function and responses to aid in drug screening and disease model development. Recent developments in microfabrication techniques and cellular materials enabled fabrication of next-generation, advanced microphysiological systems (MPSs) that aim to capture the cellular complexity and dynamic nature of the organ presenting highly controlled extracellular cues to cells in a physiologically relevant context. Historically, MPSs have heavily relied on elastomeric materials in their manufacture, with unfavorable material characteristics (such as lack of structural rigidity) limiting their use in high-throughput systems.

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Microphysiological systems (MPSs) are dynamic cell culture systems that provide micro-environmental and external cues to support physiologically relevant, organ-specific functions. Recent progresses in MPS fabrication technologies have enabled the development of advanced models to capture microenvironments with physiological relevance, while increasing throughput and reducing material-based artefacts. In addition to conventional cell culture systems, advanced MPSs are emerging as ideal contenders for disease modeling and incorporation into drug screening.

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Cathepsins K and V are powerful elastases elevated in endothelial cells by tumor necrosis factor-α (TNFα) stimulation and disturbed blood flow both of which contribute to inflammation-mediated arterial remodeling. However, mechanisms behind endothelial cell integration of biochemical and biomechanical cues to regulate cathepsin production are not known. To distinguish these mechanisms, human aortic endothelial cells (HAECs) were stimulated with TNFα and exposed to pro-remodeling or vasoprotective shear stress profiles.

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Monitoring patient adherence to HIV antiretroviral therapy (ART) by patient survey is inherently error prone, justifying a need for objective, biological measures affordable in low-resource settings where HIV/AIDS epidemic is highest. In preliminary studies conducted in Ethiopia and South Africa, we observed loss of cysteine cathepsin activity in peripheral blood mononuclear cells of HIV-positive patients on ART. We optimized a rapid protocol for multiplex cathepsin zymography to quantify cysteine cathepsins, and prospectively enrolled 350 HIV-positive, ART-naïve adults attending the Themba Lethu Clinic, Johannesburg, South Africa, to test if suppressed cathepsin activity could be a biomarker of ART adherence (103 patients were included in final analysis).

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Fibrin is an extracellular matrix protein that is responsible for maintaining the structural integrity of blood clots. Much research has been done on fibrin in the past years to include the investigation of synthesis, structure-function, and lysis of clots. However, there is still much unknown about the morphological and structural features of clots that ensue from patients with disease.

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Sphingolipids are a class of lipids containing a backbone of sphingoid bases that can be produced de novo through the reaction of palmitate and serine and further metabolized through the activity of various enzymes to produce intermediates with diverse roles in cellular processes and signal transduction. One of these intermediates, sphingosine 1-phosphate (S1P), is stored at high concentrations (1 μM) in red blood cells (RBCs) and directs a wide array of cellular processes mediated by 5 known G-protein coupled receptors (S1P1-S1P5). In this study, we show that RBC membrane alterations in sickle cell disease enhance the activation acid sphingomyelinase by 13%, resulting in increased production and storage of sphingosine (2.

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Inflammation and damage promote monocyte adhesion to endothelium and cardiovascular disease (CVD). Elevated inflammation and increased monocyte-endothelial cell interactions represent the initial stages of vascular remodeling associated with a multitude of CVDs. Cathepsins are proteases produced by both cell types that degrade elastin and collagen in arterial walls, and are upregulated in CVD.

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Sickle cell disease is a genetic disease that increases systemic inflammation as well as the risk of pediatric strokes, but links between sickle-induced inflammation and arterial remodeling are not clear. Cathepsins are powerful elastases and collagenases secreted by endothelial cells and monocyte-derived macrophages in atherosclerosis, but their involvement in sickle cell disease has not been studied. Here, we investigated how tumor necrosis alpha (TNFα) and circulating mononuclear cell adhesion to human aortic endothelial cells (ECs) increase active cathepsins K and V as a model of inflammation occurring in the arterial wall.

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A range of chiral, optically-enriched bicyclic oxabispidines were prepared from (S)-(-)-2,3-epoxypropylphthalimide using an efficient sequence featuring a stereocontrolled intramolecular Mannich reaction as the key transformation.

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Treatment of glycidyl sulfonamides with LDA delivers the corresponding enesulfonamide with good selectivity for the E-isomer, whereas the corresponding carbamates exhibit selectivity for the Z-enecarbamate. An E1cB elimination mechanism proceeding from a substrate-base chelate complex is advanced as rationalisation of the latter set of Z-selective outcomes.

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Cathepsins K, L, S, and V are cysteine proteases that have been implicated in tissue-destructive diseases such as atherosclerosis, tumor metastasis, and osteoporosis. Among these four cathepsins are the most powerful human collagenases and elastases, and they share 60% sequence homology. Proper quantification of mature, active cathepsins has been confounded by inhibitor and reporter substrate cross-reactivity, but is necessary to develop properly dosed therapeutic applications.

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Objective: • To describe the incidence of the development of male genital lichen sclerosus (LS) in non-genital skin grafts used in penile reconstruction after cancer surgery.

Patients And Methods: • Between 1997 and 2009, 177 patients received surgical treatment for penile cancer in the Urology Department at Sunderland Royal Hospital, the regional penile cancer centre for the north-east of England. • Patients who had organ-sparing surgery and non-genital penile graft reconstructions were identified.

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Cathepsin K, the most potent mammalian collagenase, has been implicated in osteoporosis, cancer metastasis, atherosclerosis, and arthritis. Although procathepsin K is stable and readily detected, the active mature cathepsin K eludes detection by in vitro methods due to its shorter half-life and inactivation at neutral pH. We describe, for the first time, reliable detection, visualization, and quantification of mature cathepsin K to femtomole resolution using gelatin zymography.

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