Electrospun Quaternized Chitosan Fibers for Virus Removal from Drinking Water

Membrane filtration has become an accepted technology for the removal of pathogens from drinking water. Viruses, known to contaminate water supplies, are too small to be removed by a size-exclusion mechanism without a large energy penalty. Thus, functionalized electrospun membranes that can adsorb viruses have drawn our interest. We chose a quaternized chitosan derivative (HTCC) which carries a positively-charged quaternary amine, known to bind negatively-charged virus particles, as a functionalized membrane material. The technique of electrospinning was utilized to produce nanofiber mats with large pore diameters to increase water flux and decrease membrane fouling. In this study, stable, functionalized, electrospun HTCC-PVA nanofibers that can remove 3.6 logs (99.97%) of a model virus, porcine parvovirus (PPV), from water by adsorption and filtration have been successfully produced. This technology has the potential to purify drinking water in undeveloped countries and reduce the number of deaths due to lack of sanitation.

Arthroscopically assisted removal of intraosseous ganglion cysts of the distal tibia

Intraosseous ganglia of the distal tibia are rare. We evaluated the feasibility of surgically treating these lesions with an arthroscopically assisted technique. Five patients with symptomatic distal tibial ganglia underwent surgical curettage and excision with this technique. All patients underwent débridement of the chondral lesion and hypertrophied synovial lining when present, probing of the portal to the ganglion, and subsequently thorough curettage with bone grafting performed through a cortical window made from a separate small incision. Biopsy confirmed the diagnosis in all patients. All patients had eventual relief of symptoms with good integration of bone graft at final followup. There were no recurrences at a minimum followup of 19 months (mean, 38.6 months; range, 19-69 months). Mean time for return to full function was 15.4 weeks (range, 8-17 weeks). There were no intraoperative or postoperative complications. The mean American Orthopaedic Foot and Ankle Society scores increased from 73 points (range, 67-77 points) preoperatively to 94 points (range, 90-100 points) postoperatively. Arthroscopically assisted surgical treatment of ganglia of the distal tibia in the appropriate patient is a reasonably simple technique that relieves symptoms and helps the patient to regain normal gait and full function with no recurrence (in our small series). LEVEL OF EVIDENCE: Level IV, case series. See Guidelines for Authors for a complete description of levels of evidence.

Selective removal of anomeric O-acetate groups in carbohydrates using HCl04-Si02-tr

A convenient methodology has been developed for the selective removal of the anomeric acyl group of carbohydrate derivatives using HCI04-Si02 under acidic reaction conditions. Anomeric benzoyl groups can also be removed selectively following similar reaction conditions. The yields were excellent in all cases.

Ctp1CtIP and Rad32Mre11 nuclease activity are required for Rec12Spo11 removal, but Rec12Spo11 removal is dispensable for other MRN-dependent meiotic functions

The evolutionarily conserved Mre11/Rad50/Nbs1 (MRN) complex is involved in various aspects of meiosis. Whereas available evidence suggests that the Mre11 nuclease activity might be responsible for Spo11 removal in Saccharomyces cerevisiae, this has not been confirmed experimentally. This study demonstrates for the first time that Mre11 (Schizosaccharomyces pombe Rad32(Mre11)) nuclease activity is required for the removal of Rec12(Spo11). Furthermore, we show that the CtIP homologue Ctp1 is required for Rec12(Spo11) removal, confirming functional conservation between Ctp1(CtIP) and the more distantly related Sae2 protein from Saccharomyces cerevisiae. Finally, we show that the MRN complex is required for meiotic recombination, chromatin remodeling at the ade6-M26 recombination hot spot, and formation of linear elements (which are the equivalent of the synaptonemal complex found in other eukaryotes) but that all of these functions are proficient in a rad50S mutant, which is deficient for Rec12(Spo11) removal. These observations suggest that the conserved role of the MRN complex in these meiotic functions is independent of Rec12(Spo11) removal.

Ctp1 and the MRN-complex are required for endonucleolytic Rec12 removal with release of a single class of oligonucleotides in fission yeast

DNA double-strand breaks (DSBs) are formed during meiosis by the action of the topoisomerase-like Spo11/Rec12 protein, which remains covalently bound to the 5' ends of the broken DNA. Spo11/Rec12 removal is required for resection and initiation of strand invasion for DSB repair. It was previously shown that budding yeast Spo11, the homolog of fission yeast Rec12, is removed from DNA by endonucleolytic cleavage. The release of two Spo11 bound oligonucleotide classes, heterogeneous in length, led to the conjecture of asymmetric cleavage. In fission yeast, we found only one class of oligonucleotides bound to Rec12 ranging in length from 17 to 27 nucleotides. Ctp1, Rad50, and the nuclease activity of Rad32, the fission yeast homolog of Mre11, are required for endonucleolytic Rec12 removal. Further, we detected no Rec12 removal in a rad50S mutant. However, strains with additional loss of components localizing to the linear elements, Hop1 or Mek1, showed some Rec12 removal, a restoration depending on Ctp1 and Rad32 nuclease activity. But, deletion of hop1 or mek1 did not suppress the phenotypes of ctp1Delta and the nuclease dead mutant (rad32-D65N). We discuss what consequences for subsequent repair a single class of Rec12-oligonucleotides may have during meiotic recombination in fission yeast in comparison to two classes of Spo11-oligonucleotides in budding yeast. Furthermore, we hypothesize on the participation of Hop1 and Mek1 in Rec12 removal.

Near-infrared digital photography to estimate snow correlation length for microwave emission modeling

The study is based on experimental work conducted in alpine snow. We made microwave radiometric and near-infrared reflectance measurements of snow slabs under different experimental conditions. We used an empirical relation to link near-infrared reflectance of snow to the specific surface area (SSA), and converted the SSA into the correlation length. From the measurements of snow radiances at 21 and 35 GHz , we derived the microwave scattering coefficient by inverting two coupled radiative transfer models (the sandwich and six-flux model). The correlation lengths found are in the same range as those determined in the literature using cold laboratory work. The technique shows great potential in the determination of the snow correlation length under field conditions.

Right ventricular rupture after lateral thoracotomy for removal of rib-associated telangiectatic osteosarcoma in a dog

OBJECTIVE: To describe a case of a focal right ventricular rupture following removal of a rib-associated telangiectatic osteosarcoma (TOS) in a dog. CASE SUMMARY: A 2-year-old spayed female mixed-breed dog, weighing 20 kg, was presented in compensated hypovolemic shock due to active bleeding into the thoracic cavity. The dog was stabilized with appropriate fluid administration. Subsequent computed tomographic examination revealed a large mineralized mass originating from the body of a rib and displacing the heart. Two days after surgical removal of this mass, focal right ventricular rupture occurred and the dog died. The mass was later identified as a TOS. NEW OR UNIQUE INFORMATION PROVIDED: Although hemothorax secondary to TOS has been described previously, this report describes for the first time, spontaneous focal right ventricular rupture as a rare complication of thoracotomy and rib resection for the removal of a rib-associated, intrathoracic TOS.