PurposeTo characterize the ocular surface microbiome of healthy volunteers using a combination of microbial culture and high-throughput DNA sequencing techniques.MethodsConjunctival swab samples from 107 healthy volunteers were analyzed by bacterial culture, 16S rDNA gene deep sequencing (n = 89), and biome representational in silico karyotyping (BRiSK; n = 80). Swab samples of the facial skin (n = 42), buccal mucosa (n = 50), and environmental controls (n = 27) were processed in parallel. 16S rDNA gene quantitative PCR was used to calculate the bacterial load in each site. Bacteria were characterized by site using principal coordinate analysis of metagenomics data. BRiSK data were analyzed for presence of fungi and viruses.ResultsCorynebacteria, Propionibacteria, and coagulase-negative Staphylococci were the predominant organisms identified by all three techniques. Quantitative 16S PCR demonstrated approximately 0.1 bacterial 16S rDNA/human actin copy on the ocular surface compared with greater than 10 16S rDNA/human actin copy for facial skin or the buccal mucosa. The conjunctival bacterial community structure is distinct compared with the facial skin (R = 0.474, analysis of similarities P = 0.0001), the buccal mucosa (R = 0.893, P = 0.0001), and environmental control samples (R = 0.536, P = 0.0001). 16S metagenomics revealed substantially more bacterial diversity on the ocular surface than other techniques, which appears to be artifactual. BRiSK revealed presence of torque teno virus (TTV) on the healthy ocular surface, which was confirmed by direct PCR to be present in 65% of all conjunctiva samples tested.ConclusionsRelative to adjacent skin or other mucosa, healthy ocular surface microbiome is paucibacterial. Its flora are distinct from adjacent skin. Torque teno virus is a frequent constituent of the ocular surface microbiome. (ClinicalTrials.gov number, NCT02298881.)

Mice lacking the oxalate transporter SLC26A6 develop hyperoxalemia, hyperoxaluria, and calciumoxalate stones as a result of a defect in intestinal oxalate secretion, but what accounts for the absorptive oxalate flux remains unknown. We measured transepithelial absorption of [14 C]oxalate simultaneously with the flux of [ 3 H]mannitol, a marker of the paracellular pathway, across intestine from wild-type and Slc26a6-null mice. We used the anion transport inhibitor DIDS to investigate other members of the SLC26 family that may mediate transcellular oxalate absorption. Absorptive flux of oxalate in duodenum was similar to mannitol, insensitive to DIDS, and nonsaturable, indicating that it is predominantly passive and paracellular. In contrast, in wild-type mice, secretory flux of oxalate in duodenum exceeded that of mannitol, was sensitive to DIDS, and saturable, indicating transcellular secretion of oxalate. In Slc26a6-null mice, secretory flux of oxalate was similar to mannitol, and no net flux of oxalate occurred. Absorptive fluxes of both oxalate and mannitol varied in parallel in different segments of small and large intestine. In epithelial cell lines, modulation of the charge selectivity of the claudin-based pore pathway did not affect oxalate permeability, but knockdown of the tight-junction protein ZO-1 enhanced permeability to oxalate and mannitol in parallel. Moreover, formation of soluble complexes with cations did not affect oxalate absorption. In conclusion, absorptive oxalate flux occurs through the paracellular "leak" pathway, and net absorption of dietary oxalate depends on the relative balance between absorption and SLC26A6-dependent transcellular secretion. 22: 224722: -225522: , 201122: . doi: 10.1681 Nephrolithiasis is the second most common chronic kidney condition after hypertension and demonstrates a rising prevalence and association with chronic kidney disease. 1 Calcium oxalate (CaOx) is the predominant component of most stones, and the level of urinary oxalate is an important risk factor for CaOx nephrolithiasis. 2,3 The amount of urinary oxalate depends on the net effect of metabolic production, intestinal absorption, and renal excretion. 4 The integral role of the intestine in oxalate homeostasis becomes most evident in diseases of intestine. Inflammatory bowel disease and small-bowel resections are conditions that are strongly associated with hyperoxaluria and CaOx nephrolithiasis. 5 New insight into the importance of the intestine in the pathogenesis of CaOx nephrolithiasis has come from studies of anion transporter SLC26A6. Slc26a6-null mice have a defect in in- J Am Soc Nephrol

Fully covalently connected polymer−clay nanocomposites have been prepared by growing the polymer chains from initiator sites on the lamellae of a zirconium phosphonate clay. The zirconium phosphonate material was synthesized with an approximately 1:3 ratio of 4-aminobenzylphosphonate and ethylphosphonate groups (Zr(AbPO3) x (EtPO3)2- x , x ≈ 0.5) in a “solid solution” distribution within the lamellae. After conversion of the amine groups to 2-bromo-2-methylpropionamide moieties, composites of the zirconium phosphonate and tethered poly(methyl methacrylate) (PMMA) brushes were synthesized by atom transfer radical polymerization (ATRP); the tethered initiator within Zr(Init-AbPO3) x (EtPO3)2- x and its soluble analogue are the first examples of aromatic amide-based initiators for ATRP. To facilitate characterization of the composites, the polymerization conditions were intentionally not optimized for high molecular weight polymer, but PMMA was nonetheless formed at the conditions studied, and the weight fraction of polymer was observed to increase with polymerization time. A combination of thermogravimetric analysis, 13C CP MAS NMR, X-ray diffraction, and scanning electron microscopy confirmed the compositions and structures of the composites, including the covalent connectivity among all of the components.

PS. Sat1 is dispensable for active oxalate secretion in mouse duodenum.

Our study highlights both advantages and limitations of OCT compared with technician SLE in the evaluation of donor corneal tissue. Although OCT may miss some peripheral lesions and LASIK scars that are identifiable on SLE, OCT's depth resolution is helpful in differentiating whether shallow anterior opacities actually extend deeper into the stroma or are confined superficially to the epithelium.