Allograft Tissue for Use in Valve Replacement

Homograft or allograft tissue has been available for use as replacement for diseased valves or reconstruction of major vessels for decades. However, with respect to replacement of diseased valvular tissue the search for the ideal valve still continues. In this review we will discuss the clinical indications, surgical techniques, and outcome of aortic homografts.     

Synthesis and activity against HBV of novel Tetra-seconucleoside analogues of dyphlline having the acyclic chains of ACV and HBG

Selective alkylation of dyphylline (1) with (2-acetoxyethoxy)methyl bromide (2a) or 4-acetoxybutyl bromide (2b) afforded 3'-O-[(acetoxyethoxy)methyl]dyphylline (3a) and 3'-O-(4-acetoxybutyl)-dyphylline (3b), respectively. A trans esterification process rather than alkylation of the dihydroxy-propyl side chain in 1 had taken place during the reaction with 2-p-toluoyloxy)ethyl chloride (5) to afford the respective 3'-toluoyloxy derivative 7 and not the anticipated 3'-O-[(p-toluoyloxy)ethyl]-dyphylline (6). Deacylation of 3a,b and 7 afforded 4a,b and 1, respectively. Viral screening of selected compounds against HBV has been investigated.     

Chemical compositions and antimicrobial activities of four different Anatolian propolis samples

Propolis means a gum that is gathered by bees from various plants. It is known for its biological properties, having antibacterial, antifungal and healing properties. The aims of this study were to evaluate the antimicrobial activity of four different Anatolian propolis samples on different groups of microorganisms including some oral pathogens and comparison between their chemical compositions. Ethanol extracts of propolis (EEP) were prepared from four different Anatolian propolis samples and examined whether EEP inhibit the growth of the test microorganisms or not. For the antimicrobial activity assays, minimum inhibitory concentrations (MIC) were determined by using macrodilution method. The MIC values of the most effective propolis (TB) were 2 microg/ml for Streptococcus sobrinus and Enterococcus faecalis, 4 microg/ml for Micrococcus luteus, Candida albicans and C. krusei, 8 microg/ml for Streptococcus mutans, Staphylococcus aureus, Staphylococcus epidermidis and Enterobacter aerogenes, 16 microg/ml for Escherichia coli and C. tropicalis and 32 microg/ml for Salmonella typhimurium and Pseudomonas aeruginosa. The chemical compositions of EEP's were determined by high-temperature high-resolution gas chromatography coupled to mass spectrometry. The main compounds of four Anatolian propolis samples were flavonoids such as pinocembrin, pinostropin, isalpinin, pinobanksin, quercetin, naringenin, galangine and chrysin. Although propolis samples were collected from different regions of Anatolia all showed significant antimicrobial activity against the Gram positive bacteria and yeasts. Propolis can prevent dental caries since it demonstrated significant antimicrobial activity against the microorganisms such as Streptococcus mutans, Streptococcus sobrinus and C. albicans, which involves in oral diseases.     

Nonredundant role of Bax and Bak in Bid-mediated apoptosis

Animal models suggest that Bax and Bak play an essential role in the implementation of apoptosis and as a result can hinder tumorigenesis. We analyzed the expression of these proteins in 50 human glioblastoma multiforme (GBM) tumors. We found that all the tumors expressed Bak, while three did not express Bax. In vitro, Bax-deficient GBM (BdGBM) exhibited an important resistance to various apoptogenic stimuli (e.g., UV, staurosporine, and doxorubicin) compared to the Bax-expressing GBM (BeGBM). Using an antisense strategy, we generated Bak(-) BeGBM and Bak(-) BdGBM, which enabled us to show that the remaining sensitivity of the BdGBM to apoptosis was due to the overexpression of Bak. Bax/Bak single or double deficiency had no influence on either the clonogenicity or the growth of tumors in Swiss nude mice. Of note, Bak(-) BeGBM cells were resistant to apoptosis induced by caspase 8 (C8) but not to that induced by granzyme B (GrB). Cells lacking both Bax and Bak (i.e., Bak(-) BdGBM) were completely resistant to all stimuli including the microinjection of C8 and GrB. We show that GrB-cleaved Bid and C8-cleaved Bid differ in size and utilize preferentially Bax and Bak, respectively, to promote cytochrome c release from mitochondria. Our results suggest that Bax deficiency is compensated by an increase of the expression of Bak in GBM and show, for the first time in human cancer, that the double Bax and Bak deficiency severely impairs the apoptotic program.     

Alveolar mimics with periodic strain and its effect on the cell layer formation

We report on the development of a new model of alveolar air–tissue interface on a chip. The model consists of an array of suspended hexagonal monolayers of gelatin nanofibers supported by microframes and a microfluidic device for the patch integration. The suspended monolayers are deformed to a central displacement of 40–80 µm at the air–liquid interface by application of air pressure in the range of 200–1,000 Pa. With respect to the diameter of the monolayers, that is, 500 µm, this displacement corresponds to a linear strain of 2–10% in agreement with the physiological strain range in the lung alveoli. The culture of A549 cells on the monolayers for an incubation time of 1–3 days showed viability in the model. We exerted a periodic strain of 5% at a frequency of 0.2 Hz for 1 hr to the cells. We found that the cells were strongly coupled to the nanofibers, but the strain reduced the coupling and induced remodeling of the actin cytoskeleton, which led to a better tissue formation. Our model can serve as a versatile tool in lung investigations such as in inhalation toxicology and therapy.     

Pathology of the human pulmonary paracoccidioidomycosis

Lungs of twelve patients with chronic paracoccidioidomycosis (Pb) were studied in an attempt to understand the pathogenesis of the pulmonary disease. Ribbons of the lung parenchyma including the hilar region and directed towards apical, basal and lateral regions were subdivided into sections from the hilar, intermediate and peripheral segments. The following histopathological reactions directly or indirectly related to P. brasiliensis were described and analysed in relation to the number of slides studied and the pulmonary region involved: (1) pneumonic reaction; (2) early granulomatous formation; (3) mature and healed granulomata; (4) mixed pattern (early and mature granuloma in the same pulmonary area visualized in the slide); (5) pulmonary fibrosis.It was concluded that chronic pulmonary Pb is a recurrent disease affecting equally both lungs. Fibrosis was connected mainly with the progressive evolution of the granulomata towards cicatrization and to a lesser degree probably to a direct induction by the fungi. Based chiefly on the tendency of the fibrosis to run around bronchi and to make up septa interconnecting bronchi and vessels it was hipothesized that these findings were the result of a previous chronic specific lymphangitis by the fungi. Hilar fibrosis would be the result of this lymphangitis and/or of the progression of the specific granulomatous reaction seen in the hilar lymph nodes.Non specific forms of arteritis and areas of destructive emphysema related to granulomatous inflammation and fibrosis were described. Three cases developed pulmonary hypertension.     

Piezoelectric biosensors for biorecognition analysis: application to the kinetic study of HIV-1 Vif protein binding to recombinant antibodies

In this work three piezoelectric sensors modified with anti-HIV-1 Vif (virion infectivity factor) single fragment antibodies (4BL scFV), single domains (VH) and camelized single domains (VHD) were constructed and used to detect HIV1 Vif in liquid samples. Dithio-bis-succinimidyl-undecanoate (DSU) and 11-hydroxy-1-undecanethiol (HUT) mixed self assembled monolayers (SAM) were generated at the sensors surface onto which the antibodies were immobilized. All sensors detected specifically the target HIV1-Vif antigen in solution and no unspecific binding was monitored. Impedance analysis was performed to quantify electroacoustic and viscoelastic interferences during antibody immobilization and antigen recognition. The elimination of such interferences enabled the quantitative use of the piezoelectric immunosensors to estimate the antibody surface density as well as antigen binding and equilibrium constants. In spite of the possible limitation regarding mass transport and other related molecular phenomena, which were not considered in the binding model used, this work demonstrates the usefulness of piezoelectric biosensors in biorecognition analysis and evidences the advantages on using simultaneous impedance analysis to bring analytical significance to measured data, and thus to improve piezoelectric sensors sensitivity and applicability.     

PIKfyve activity regulates reformation of terminal storage lysosomes from endolysosomes

The protein complex composed of the kinase PIKfyve, the phosphatase FIG4 and the scaffolding protein VAC14 regulates the metabolism of phosphatidylinositol 3,5‐bisphosphate, which serves as both a signaling lipid and the major precursor for phosphatidylinositol 5‐phosphate. This complex is involved in the homeostasis of late endocytic compartments, but its precise role in maintaining the dynamic equilibrium of late endosomes, endolysosomes and lysosomes remains to be determined. Here, we report that inhibition of PIKfyve activity impairs terminal lysosome reformation from acidic and hydrolase‐active, but enlarged endolysosomes. Our live‐cell imaging and electron tomography data show that PIKfyve activity regulates extensive membrane remodeling that initiates reformation of lysosomes from endolysosomes. Altogether, our findings show that PIKfyve activity is required to maintain the dynamic equilibrium of late endocytic compartments by regulating the reformation of terminal storage lysosomes.      

Squaramides as novel class I and IIB histone deacetylase inhibitors for topical treatment of cutaneous t-cell lymphoma

A series of squaramide-based hydroxamic acids were designed, synthesized and evaluated against human HDAC enzyme. Squaramides were found to be potent in the Hut78 cell line, but initially suffered from low solubility. Leads with improved solubility and metabolic profiles were shown to be class I, IIB and IV selective.