Thermogelling aqueous solutions of alternating multiblock copolymers of poly(L-lactic acid) and poly(ethylene glycol)

We are reporting alternating multiblock copolymers of poly(L-lactic acid)/poly(ethylene glycol) aqueous solution (> 15 wt %) undergoing sol-gel-sol transition as the temperature increases from 20 to 60 degrees C. Micelles of the multiblock copolymers (in water) are about 20 nm in radius at low temperature. They are aggregated to a larger size as the temperature increases, which should play a critical role in the sol-to-gel transition. The transition temperature and gel window were affected by the molecular weight and composition of the multiblock copolymer. In particular, the aqueous solution of an alternating multiblock copolymer (Mn approximately 6700 daltons) prepared from poly(ethylene glycol) (Mn approximately 600 daltons) and poly(L-lactic acid) (Mn approximately 1300 daltons) showed a maximum modulus at body temperature (37 degrees C). The in situ gel forming ability of the polymer aqueous solution in vivo as well as in vitro indicates that it can be a promising injectable biomaterial.     

Biomimetic nanofibrous scaffolds: preparation and characterization of PGA/chitin blend nanofibers

Electrospinning of poly(glycolic acid) (PGA)/chitin blend solutions in 1,1,1,3,3,3-hexafluoro-2-propanol was investigated to fabricate biodegradable and biomimetic nanostructured scaffolds for tissue engineering. The morphology of the electrospun PGA/chitin blend nanofibers was investigated with a field emission scanning electron microscope. The PGA/chitin blend fibers have average diameters of around 140 nm, and their diameters have a distribution in the range 50-350 nm. The miscibility of PGA/chitin blend fibers was examined by differential scanning calorimetry. The PGA and chitin were immiscible in the as-spun nanofibrous structure. An in vitro degradation study of PGA/chitin blend nanofibers was conducted in phosphate-buffered saline, pH 7.2. It was found that the hydrolytic cleavage of PGA in the blend nanofibers was accelerated by the coexistence of hydrophilic chitin. To assay the cytocompatability and cell behavior on the PGA/chitin blend nanofibrous scaffolds, cell attachment and spreading of normal human epidermal fibroblasts seeded on the scaffolds were studied. Our results indicate that the PGA/chitin blend nanofibrous matrix, particularly the one that contained 25% PGA and 75% chitin with bovine serum albumin coating, could be a good candidate for tissue engineering scaffolds, because it has an excellent cell attachment and spreading for normal human fibroblasts.     

Immunomodulatory properties of Enterococcus faecium JWS 833 isolated from duck intestinal tract and suppression of Listeria monocytogenes infection

The aim of this study was to evaluate the immunomodulatory properties of Enterococcus faecium JWS 833 (JWS 833) isolated from duck intestine and compare them to those of Lactobacillus rhamnosus GG (LGG), a proven immunity-enhancing probiotic. To investigate the immune-enhancing properties of JWS 833, production of nitric oxide (NO) and cytokines was measured in mouse peritoneal macrophages. In addition, a Listeria monocytogenes challenge model was used in the assessment. It was found that heat-killed JWS 833 stimulates mouse peritoneal macrophages to produce NO, interleukin-1 β (IL-1β) and tumor necrosis factor-α (TNF-α) and that oral administration of viable JWS833 enhances NO, IL-1β and TNF-α synthesis upon L. monocytogenes challenge. Moreover, mice fed with JWS 833 were partially protected against lethal challenge with L. monocytogenes. JWS 833 strain has significantly greater immunostimulatory properties than LGG. Moreover, JWS 833 strain partially protects mice against lethal challenge with L. monocytogenes. JWS 833, a novel strain of E. faecium isolated from duck intestine, is potentially a useful feed supplement for controlling pathogens and enhancing host immune responses.     

CAPS markers using mitochondrial consensus primers for molecular identification of Panax species and Korean ginseng cultivars (Panax ginseng C. A. Meyer)

Cleaved amplified polymorphic sequence (CAPS) marker system using mitochondrial consensus primers was applied for molecular identification of Korean ginseng cultivars (Panax ginseng). Initially, a total of 34 primers were tested to six Korean ginseng cultivars and two foreign Panax species, P. quinquefolius and P. notoginseng. In the polymerase chain reaction (PCR) amplification results, four primers (mt7, mt11, mt13, and mt18) generated co-dominant polymorphic banding patterns discriminating the Korean ginseng cultivars from P. quinquefolius and P. notoginseng. In the CAPS analysis results, the majority of the cleaved PCR products also yielded additional latent polymorphisms between the Korean ginseng cultivars and two foreign Panax species. Specific latent CAPS polymorphisms for cultivar Gopoong and Chunpoong were detected from internal region amplified with mt9 primer by treating HinfI and Tsp509I endonucleases, respectively. Sequencing analysis revealed that the length of amplified region of Korean ginseng cultivars was 2,179 bp, and those of P. quinquefolius and P. notoginseng were 2,178 and 2,185 bp, respectively. Blast search revealed that the amplified region was a mitochondrial cytochrome oxidase subunit 2 (cox2) gene intron II region. Nineteen single nucleotide polymorphisms (SNP) including each specific SNP for Gopoong and Chunpoong, and three insertion and deletion (InDel) polymorphisms were detected by sequence alignment. The CAPS markers developed in this study, which are specific to Gopoong and Chunpoong, and between the Korean ginseng cultivars and two foreign Panax species, will serve as a practical and reliable tool for their identification, purity maintenance, and selection of candidate lines and cultivars.     

Know Your Enemy: How to Build and Vanquish a Global Fungal Scourge

The 8th International Conference on Cryptococcus and Cryptococcosis, chaired by Maurizio Del Poeta (Medical University of South Carolina), and organized together with June Kwon-Chung (National Institute of Allergy and Infectious Diseases), Stuart Levitz (University of Massachusetts Medical School), and John Perfect (Duke University), occurred in May 2011. This meeting brought together the world's leading researchers on Cryptococcus and cryptococcosis, including basic scientists, epidemiologists, and clinicians, to discuss new developments in Cryptococcus biology. With more than 60 oral presentations and 180 posters, this meeting enhanced our understanding of pathogenicity of Cryptococcus and served as a robust forum that facilitated cross-disciplinary discussions, research, and clinical collaborations. Due to space constraints, this brief overview highlights only a few of the topics discussed in this meeting, focusing on the evolution of virulence, host and pathogen interactions, fungal and host signaling, new advances of genomics studies on Cryptococcus, and the current status of the outbreak caused by C. gattii. The 8th International Conference on Cryptococcus and Cryptococcosis brought together scientists from across the globe in the beautiful historical downtown setting of Charleston to share their latest findings and highlight advances in Cryptococcus research. With more than 250 participants, this meeting was the largest gathering of the Cryptococcus international community in the 24-year history. Here, we review the advances presented and the current state of knowledge in the field.     

Mechanisms and consequences of TGF-? overexpression by podocytes in progressive podocyte disease

In patients with progressive podocyte disease, such as focal segmental glomerulosclerosis (FSGS) and membranous nephropathy, upregulation of transforming growth factor-? (TGF-?) is observed in podocytes. Mechanical pressure or biomechanical strain in podocytopathies may cause overexpression of TGF-? and angiotensin II (Ang II). Oxidative stress induced by Ang II may activate the latent TGF-?, which then activates Smads and Ras/extracellular signal-regulated kinase (ERK) signaling pathways in podocytes. Enhanced TGF-? activity in podocytes may lead to thickening of the glomerular basement membrane (GBM) by overproduction of GBM proteins and impaired GBM degradation in podocyte disease. It may also lead to podocyte apoptosis and detachment from the GBM, and epithelial-mesenchymal transition (EMT) of podocytes, initiating the development of glomerulosclerosis. Furthermore, activated TGF-?/Smad signaling by podocytes may induce connective tissue growth factor and vascular endothelial growth factor overexpression, which could act as a paracrine effector mechanism on mesangial cells to stimulate mesangial matrix synthesis. In proliferative podocytopathies, such as cellular or collapsing FSGS, TGF-?-induced ERK activation may play a role in podocyte proliferation, possibly via TGF-?-induced EMT of podocytes. Collectively, these data bring new mechanistic insights into our understanding of the TGF-? overexpression by podocytes in progressive podocyte disease.     

Klebsiella pneumoniae secretes outer membrane vesicles that induce the innate immune response

Outer membrane vesicles (OMVs) derived from pathogenic Gram-negative bacteria are an important vehicle for delivery of effector molecules to host cells, but the production of OMVs from Klebsiella pneumoniae, an opportunistic pathogen of both nosocomial and community-acquired infections, and their role in bacterial pathogenesis have not yet been determined. In the present study, we examined the production of OMVs from K. pneumoniae and determined the induction of the innate immune response against K. pneumoniae OMVs. Klebsiella pneumoniae ATCC 13883 produced and secreted OMVs during in vitro culture. Proteomic analysis revealed that 159 different proteins were associated with K. pneumoniae OMVs. Klebsiella pneumoniae OMVs did not inhibit cell growth or induce cell death. However, these vesicles induced expression of proinflammatory cytokine genes such as interleukin (IL)-1β and IL-8 in epithelial cells. An intratracheal challenge of K. pneumoniae OMVs in neutropenic mice resulted in severe lung pathology similar to K. pneumoniae infection. In conclusion, K. pneumoniae produces OMVs like other pathogenic Gram-negative bacteria and K. pneumoniae OMVs are a molecular complex that induces the innate immune response.     

Genetically Engineered Mesenchymal Stem Cells as a Proposed Therapeutic for Huntington’s Disease

There is much interest in the use of mesenchymal stem cells/marrow stromal cells (MSC) to treat neurodegenerative disorders, in particular those that are fatal and difficult to treat, such as Huntington's disease. MSC present a promising tool for cell therapy and are currently being tested in FDA-approved phase I-III clinical trials for many disorders. In preclinical studies of neurodegenerative disorders, MSC have demonstrated efficacy, when used as delivery vehicles for neural growth factors. A number of investigators have examined the potential benefits of innate MSC-secreted trophic support and augmented growth factors to support injured neurons. These include overexpression of brain-derived neurotrophic factor and glial-derived neurotrophic factor, using genetically engineered MSC as a vehicle to deliver the cytokines directly into the microenvironment. Proposed regenerative approaches to neurological diseases using MSC include cell therapies in which cells are delivered via intracerebral or intrathecal injection. Upon transplantation, MSC in the brain promote endogenous neuronal growth, encourage synaptic connection from damaged neurons, decrease apoptosis, reduce levels of free radicals, and regulate inflammation. These abilities are primarily modulated through paracrine actions. Clinical trials for MSC injection into the central nervous system to treat amyotrophic lateral sclerosis, traumatic brain injury, and stroke are currently ongoing. The current data in support of applying MSC-based cellular therapies to the treatment of Huntington's disease is discussed.