Download the Free Unbound MEDLINE PubMed App to your smartphone or tablet.
Available for iPhone, iPad, iPod touch, and Android.
Advances in bioscience and biotechnology [journal]
- Aging promotes pro-fibrotic matrix production and increases fibrocyte recruitment during acute lung injury. [JOURNAL ARTICLE]
- Adv Biosci Biotechnol 2014 Jan; 5(1):19-30.
Fibrotic lung diseases increase with age. Previously we determined that senescence increases tissue expression of fibronectin EDA (Fn-EDA) and decreases fibroblast expression of Thy-1, and that fibrocytes contribute to fibrosis following bleomycin-induced lung injury in mice. In this study we hypothesized that fibroblasts lacking Thy-1 expression produce an extracellular matrix that promotes fibrocyte retention and myofibroblast transdifferentiation, thereby promoting fibrogenesis. Young and old mice were treated with bleomycin intratracheally; fibrocytes in the bone marrow, blood, and lungs were quantified, and lung fibroblast Thy-1 expression assessed. Bone marrow-derived fibrocytes were cultured on matrices derived from Thy-1(+) or Thy-1(-) fibroblasts ± the pro-fibrotic cytokine TGFβ1. Older mice had more fibrocytes in their bone marrows at baseline and more fibrocytes in their lungs following bleomycin treatment. In parallel, lung fibroblasts in older mice had lower expression of Thy-1 at baseline that increased transiently 7 days after bleomycin treatment but then rapidly waned such that 14 days after bleomycin treatment Thy-1 expression was again markedly lower. Fibrocytes cultured on matrices derived from Thy-1(-) fibroblasts + TGFβ1 had increased gene expression for collagen type 1, fibronectin, Fn-EDA, and α-smooth muscle actin. In parallel, whereas the matrices derived from Thy-1(-) fibroblasts stimulated phosphorylation of Akt in cultured fibrocytes, the matrices derived from Thy-1(+) fibroblasts induced apoptosis. These findings suggest that senescence increases fibrocyte recruitment to the lung following injury and that loss of Thy-1 expression by lung fibroblasts promotes fibrocyte retention and myofibroblast trans-differentiation that renders the "aging lung" susceptible to fibrosis.
- Role of TGF-β in breast cancer bone metastases. [JOURNAL ARTICLE]
- Adv Biosci Biotechnol 2013 Oct 1; 4(10C):15-30.
Breast cancer is the most prevalent cancer among females worldwide leading to approximately 350,000 deaths each year. It has long been known that cancers preferentially metastasize to particular organs, and bone metastases occur in ~70% of patients with advanced breast cancer. Breast cancer bone metastases are predominantly osteolytic and accompanied by increased fracture risk, pain, nerve compression and hypercalcemia, causing severe morbidity. In the bone matrix, transforming growth factor-β (TGF-β) is one of the most abundant growth factors, which is released in active form upon tumor-induced osteoclastic bone resorption. TGF-β, in turn, stimulates bone metastatic tumor cells to secrete factors that further drive osteolytic bone destruction adjacent to the tumor. Thus, TGF-β is a crucial factor responsible for driving the feed-forward vicious cycle of cancer growth in bone. Moreover, TGF-β activates epithelial-to-mesenchymal transition, increases tumor cell invasiveness and angiogenesis and induces immunosuppression. Blocking the TGF-β signaling pathway to interrupt this vicious cycle between breast cancer and bone offers a promising target for therapeutic intervention to decrease skeletal metastasis. This review will describe the role of TGF-β in breast cancer and bone metastasis, and pre-clinical and clinical data will be evaluated for the potential use of TGF-β inhibitors in clinical practice to treat breast cancer bone metastases.
- Cyclophosphamide Induces an Early Wave of Acrolein-Independent Apoptosis in the Urothelium. [JOURNAL ARTICLE]
- Adv Biosci Biotechnol 2013 Aug; 4(88)
Hemorrhagic cystitis (HC or bladder inflammation) affects a significant number of patients undergoing cyclophosphamide (CP) chemotherapy despite treatment with 2-mercaptoethane sulfonate (Mesna) to inactivate the metabolite acrolein. While the mechanism is unknown, there is clearly acrolein-independent damage to the urothelium. In this study we have explored the induction of apoptosis in the urothelium as a marker of damage and the mechanism underlying the acrolein-independent apoptosis.Apoptosis in urothelium (caspase-3/7 activity and Poly (ADP-ribosyl) polymerase (PARP) cleavage) was measured following CP administration (80 mg/kg). Sodium 2-mercaptoethane sulfonate (Mesna) was used to mask acrolein's effect. An IL-1β receptor antagonist and a cell-permeable caspase-1 inhibitor were used to assess the involvement of IL-1β and caspase-1, respectively.Two waves of apoptosis were detected following CP administration, one peaking at 2 h and a second at 48 h. The first wave was independent of acrolein. Caspase-1 was also active at 2 h and activation of caspase-3/7 was blocked by a caspase-1 inhibitor but not an IL-1β receptor antagonist suggesting the direct activation of caspase-3/7 by caspase-1 without the need for IL-1β as an intermediate.Our results indicate that CP initiates an early, acrolein-independent wave of apoptosis that results from direct cleavage of caspase-3/7 by caspase-1.
- Physiological effects of nickel chloride on the freshwater cyanobacterium Synechococcus sp. IU 625. [JOURNAL ARTICLE]
- Adv Biosci Biotechnol 2013 Jul; 4(7B):10-14.
Harmful algal blooms (HABs) are a serious environmental problem globally. The ability of cyanobacteria, one of the major causative agents of HABs, to grow in heavy metal polluted areas is proving a challenge to environmental restoration initiatives. Some cyanobacteria secrete toxins, such as microcystin, that are potentially dangerous to animals and humans. In this study, the physiology of a cyanobacterium was assessed to nickel chloride exposure. Cell growths were monitored throughout the study with various nickel chloride concentrations (0, 10, 25 or 50 mg/L). Morphological abnormalities were observed with microscopic image analyses. Inductively coupled plasma mass spectrometry (ICP-MS) was carried out to trace the distribution of nickel during the growth period. This study provides insight on potential nickel response mechanisms in freshwater cyanobacteria, which may lead to effective HAB prevention strategy development.
- Increased survivin expression contributes to apoptosis-resistance in IPF fibroblasts. [JOURNAL ARTICLE]
- Adv Biosci Biotechnol 2012 Oct; 3(6A):657-664.
Fibroblasts perform critical functions during the normal host response to tissue injury, but the inappropriate accumulation and persistent activation of these cells results in the development of tissue fibrosis. The mechanisms accounting for the aberrant accumulation of fibroblasts during fibrotic repair are poorly understood, although evidence supports a role for fibroblast resistance to apoptosis as a contributing factor. We have shown that TGF-β1 and endothelin-1 (ET-1), soluble mediators implicated in fibrogenesis, promote fibroblast resistance to apoptosis. Moreover, we recently found that ET-1 induced apoptosis resistance in normal lung fibroblasts through the upregulation of survivin, a member of the Inhibitor of Apoptosis (IAP) protein family. In the current study, we sought to determine the role of survivin in the apoptosis resistance of primary fibroblasts isolated from the lungs of patients with Idiopathic Pulmonary Fibrosis (IPF), a fibrotic lung disease of unclear etiology for which there is no definitive therapy. First, we examined survivin expression in lung tissue from patients with IPF and found that there is robust expression in the fibroblasts residing within fibroblastic foci (the "active" lesions in IPF which correlate with mortality). Next, we show that survivin expression is increased in fibroblasts isolated from IPF lung tissue compared to cells from normal lung tissue. Consistent with a role in fibrogenesis, we demonstrate that TGF-β1 increases survivin expression in normal lung fibroblasts. Finally, we show that inhibition of survivin enhances susceptibility of a subset of IPF fibroblasts to apoptosis. Collectively, these findings suggest that increased survivin expression represents one mechanism contributing an apoptosis-resistant phenotype in IPF fibroblasts.
- Degradation of naturally occurring and engineered antimicrobial peptides by proteases. [JOURNAL ARTICLE]
- Adv Biosci Biotechnol 2011 Dec; 2(6):404-408.
We hypothesized that current antimicrobial peptides should be susceptible to proteolytic digestion. The antimicrobial peptides: Griffithinsin, RC-101, LL-37, LSA-5, PSC-RANTES and DJ007 were degraded by commercially available proteases. Two different species of anaerobic vaginal flora, Prevotella bivia and Porphyromonas asaccharolytica also degraded the materials. Griffithsin was resistant to digestion by 8 of the 9 proteases and the bacteria while LL-37 was the most sensitive to protease digestion. These data suggests most of the molecules may not survive for very long in the proteolytic rich environments in which they are intended to function.
- pHluorin2: an enhanced, ratiometric, pH-sensitive green florescent protein. [JOURNAL ARTICLE]
- Adv Biosci Biotechnol 2011 Jun; 2(3):132-137.
Green florescent protein (GFP) variants that are sensitive to changes in pH are invaluable reagents for the analysis of protein dynamics associated with both endo- and exocytotic vesicular trafficking. Ratiometric pHluorin is a GFP variant that displays a bimodal excitation spectrum with peaks at 395 and 475 nm and an emission maximum at 509 nm. Upon acidification, pHluorin excitation at 395 nm decreases with a corresponding increase in the excitation at 475 nm. GFP2, a GFP variant that contains mammalianized codons and the folding enhancing mutation F64L, displays ~8-fold higher florescence compared to pHluorin upon excitation at 395 nm. Using GFP2 as a template, an enhanced ratiometric pHluorin (pHluorin2) construct was developed to contain fully mammalianized codons, the F64L mutation and ten of the thirteen pHluorin-specific mutations. As a result, pHluorin2 displays markedly higher florescence when compared to pHluorin while maintaining the ratiometric pH-sensitivity. Unlike native pHluorin, pHluorin2 expressed in the ligand-binding domain of the parathyroid hormone 1 receptor is readily detectable by confocal microscopy and displays a marked increase in florescence upon ligand-induced endocytosis to intracellular vesicles. Thus, pHluorin2's enhanced florescence while sustaining ratiometric pH-sensitivity represents a significant improvement for this methodological approach.
- Direct measurement of oxygen consumption rates from attached and unattached cells in a reversibly sealed, diffusionally isolated sample chamber. [JOURNAL ARTICLE]
- Adv Biosci Biotechnol 2010 Dec 1; 5(5):398-408.
Oxygen consumption is a fundamental component of metabolic networks, mitochondrial function, and global carbon cycling. To date there is no method available that allows for replicate measurements on attached and unattached biological samples without compensation for extraneous oxygen leaking into the system. Here we present the Respiratory Detection System, which is compatible with virtually any biological sample. The RDS can be used to measure oxygen uptake in microliter-scale volumes with a reversibly sealed sample chamber, which contains a porphyrin-based oxygen sensor. With the RDS, one can maintain a diffusional seal for up to three hours, allowing for the direct measurement of respiratory function of samples with fast or slow metabolic rates. The ability to easily measure oxygen uptake in small volumes with small populations or dilute samples has implications in cell biology, environmental biology, and clinical diagnostics.