2,064 research outputs found

    Trash removal methods for improved mechanical emptying of pit latrines using a screw auger

    Get PDF
    Trash in pit latrines is one of the largest challenges facing pit emptying technologies, including the powered auger (the Excrevator), developed for improved emptying in lower- and lower-middle income countries. This study focused on two trash removal methods in conjunction with pit emptying by the Excrevator: (1) simultaneous removal of trash with sludge and (2) manual trash removal prior to sludge removal. Simultaneous removal was tested by adding to the inlet of the Excrevator system two cutting heads designed to reduce the size of trash particles before entering the pipe and auger. Laboratory testing indicated that the auger will not provide the rotational speeds necessary for proper maceration of fibrous materials such as clothing, indicating that a separate maceration unit with higher rotational methods may be more appropriate. Four manual trash removal mechanisms were designed to improve on existing manual trash ‘fishing’ tools such as iron rods with fixed hooks. Two of these tools (the ‘claw’ and the ‘hook’) showed promising laboratory results and were subsequently field tested in Mzuzu, Malawi. Both tools proved more efficient than the current tools used in the field and have potential for use in Malawi

    Reduced human platelet uptake by pig livers deficient in the asialoglycoprotein receptor 1 protein

    Get PDF
    BACKGROUND: The lethal thrombocytopenia that accompanies liver xenotransplantation is a barrier to clinical application. Human platelets are bound by the asialoglycoprotein receptor (ASGR) on pig sinusoidal endothelial cells and phagocytosed. Inactivation of the ASGR1 gene in donor pigs may prevent xenotransplantation-induced thrombocytopenia. METHODS: Transcription activator-like effector nucleases (TALENs) were targeted to the ASGR1 gene in pig liver-derived cells. ASGR1 deficient pig cells were used for somatic cell nuclear transfer (SCNT). ASGR1 knock out (ASGR1-/-) fetal fibroblasts were used to produce healthy ASGR1 knock out piglets. Human platelet uptake was measured in ASGR1+/+ and ASGR1-/- livers. RESULTS: Targeted disruption of the ASGR1 gene with TALENs eliminated expression of the receptor. ASGR1-/- livers phagocytosed fewer human platelets than domestic porcine livers during perfusion. CONCLUSIONS: The use of TALENs in liver-derived cells followed by SCNT enabled the production of healthy homozygous ASGR1 knock out pigs. Livers from ASGR1-/- pigs exhibit decreased human platelet uptake. Deletion of the ASGR1 gene is a viable strategy to diminish platelet destruction in pig-to-human xenotransplantation

    Structure of the first representative of Pfam family PF04016 (DUF364) reveals enolase and Rossmann-like folds that combine to form a unique active site with a possible role in heavy-metal chelation.

    Get PDF
    The crystal structure of Dhaf4260 from Desulfitobacterium hafniense DCB-2 was determined by single-wavelength anomalous diffraction (SAD) to a resolution of 2.01 Å using the semi-automated high-throughput pipeline of the Joint Center for Structural Genomics (JCSG) as part of the NIGMS Protein Structure Initiative (PSI). This protein structure is the first representative of the PF04016 (DUF364) Pfam family and reveals a novel combination of two well known domains (an enolase N-terminal-like fold followed by a Rossmann-like domain). Structural and bioinformatic analyses reveal partial similarities to Rossmann-like methyltransferases, with residues from the enolase-like fold combining to form a unique active site that is likely to be involved in the condensation or hydrolysis of molecules implicated in the synthesis of flavins, pterins or other siderophores. The genome context of Dhaf4260 and homologs additionally supports a role in heavy-metal chelation

    The structure of BVU2987 from Bacteroides vulgatus reveals a superfamily of bacterial periplasmic proteins with possible inhibitory function.

    Get PDF
    Proteins that contain the DUF2874 domain constitute a new Pfam family PF11396. Members of this family have predominantly been identified in microbes found in the human gut and oral cavity. The crystal structure of one member of this family, BVU2987 from Bacteroides vulgatus, has been determined, revealing a ÎČ-lactamase inhibitor protein-like structure with a tandem repeat of domains. Sequence analysis and structural comparisons reveal that BVU2987 and other DUF2874 proteins are related to ÎČ-lactamase inhibitor protein, PepSY and SmpA_OmlA proteins and hence are likely to function as inhibitory proteins

    Structure of a putative NTP pyrophosphohydrolase: YP_001813558.1 from Exiguobacterium sibiricum 255-15.

    Get PDF
    The crystal structure of a putative NTPase, YP_001813558.1 from Exiguobacterium sibiricum 255-15 (PF09934, DUF2166) was determined to 1.78 Å resolution. YP_001813558.1 and its homologs (dimeric dUTPases, MazG proteins and HisE-encoded phosphoribosyl ATP pyrophosphohydrolases) form a superfamily of all-α-helical NTP pyrophosphatases. In dimeric dUTPase-like proteins, a central four-helix bundle forms the active site. However, in YP_001813558.1, an unexpected intertwined swapping of two of the helices that compose the conserved helix bundle results in a `linked dimer' that has not previously been observed for this family. Interestingly, despite this novel mode of dimerization, the metal-binding site for divalent cations, such as magnesium, that are essential for NTPase activity is still conserved. Furthermore, the active-site residues that are involved in sugar binding of the NTPs are also conserved when compared with other α-helical NTPases, but those that recognize the nucleotide bases are not conserved, suggesting a different substrate specificity
    • 

    corecore