Diffusive and convective transfer of cytokine-inducing bacterial products across hemodialysis membranes

Diffusive and convective transfer of cytokine-inducing bacterial products across hemodialysis membranes. The widespread use of bicarbonate dialysate, and high-flux and high-efficiency dialyzers have raised concerns regarding the transmembrane passage of bacterial products from the dialysate into the blood compartment. To study the mechanisms as well as magnitude of the transmembrane transfer of bacterial products from the dialysate, we developed a computerized in vitro dialysis model which provides continuous pressure recording from the arterial, venous, dialysate inflow and outflow ports. By virtue of a computer controlled on-line infusion pump, this model permits control of ultrafiltration/backfiltration. Heparinized (10 U/ml) whole blood (150 ml) was circulated through the blood compartment for 120 minutes at 100ml/min. Bicarbonate dialysate contaminated with Pseudomonas maltophilia filtrate was circulated through the dialysate compartment at 100ml/min. A two-point pressure of +10mm of Hg (ultrafiltration) was maintained for the first 60 minutes and -10mm of Hg (backfiltration) for the next 60 minutes. Whole blood samples (10 ml) were drawn from the blood at 0, 60 and 120 minutes. Peripheral blood mononuclear cells (PBMC) harvested from these samples were incubated for 24 hours in tissue culture medium. In addition, 0.5ml samples of dialysate were collected at 0, 60 and 120 minutes and incubated with PBMC from the same donor for 24 hours. After 24 hour incubation, total cell-associated IL-1Ra and IL-1β were measured by specific radioimmunoassay. Paired experiments were performed with eight high-flux synthetic membranes (polyamide) and eight low-flux cellulose membranes (hemophan). Cytokine production is expressed as pg/2.5 million PBMC. During the mandatory ultrafiltration phase of the experiment (first hour), the production of IL-1Ra by PBMC from the blood compartment rose from 515 ± 118 to 785 ± 209 with polyamide membranes, and from 1175 ± 365 to 3865 ± 1847 with hemophan membranes, suggesting diffusive transport of bacterial products across the membrane. In contrast, at the end of the backfiltration phase (second hour), there was no further rise in the production of IL-1Ra by PBMC from the blood compartment (702 ± 123 with polyamide, and 2284 ± 886 with hemophan). The production of IL-1Ra by PBMC harvested from the blood compartment of polyamide membranes at 0, 60 and 120 minutes was lower than that with hemophan membranes (P = 0.01). In contrast to IL-1Ra, the production of IL-1β by PBMC harvested from the blood compartment with both membranes was uniformly low. The results of this study demonstrate the diffusive transfer of bacterial products across dialysis membranes. Therefore, any condition that increases diffusive transport such as dialyzers with large surface areas and high blood and dialysate flow rates could potentially increase the reverse transfer of bacterial products from the dialysate. This risk is not greater for synthetic high-flux membranes such as polyamide. Further, IL-1β is a less sensitive indicator than IL-1Ra of the transmembrane passage of cytokine-inducing substances from the dialysate to blood compartment

Effects of Vegetated Field Borders on Arthropods in Cotton Fields in Eastern North Carolina

The influence, if any, of 5m wide, feral, herbaceous field borders on pest and beneficial arthropods in commercial cotton, Gossypium hirsutum (L.) (Malvales: Malvaceae), fields was measured through a variety of sampling techniques over three years. In each year, 5 fields with managed, feral vegetation borders and five fields without such borders were examined. Sampling was stratified from the field border or edge in each field in an attempt to elucidate any edge effects that might have occurred. Early season thrips populations appeared to be unaffected by the presence of a border. Pitfall sampling disclosed no differences in ground-dwelling predaceous arthropods but did detect increased populations of crickets around fields with borders. Cotton aphid (Aphis gossypii Glover) (Hemiptera: Aphididae) populations were too low during the study to adequately assess border effects. Heliothines, Heliothis virescens (F.) and Helicoverpa zea (Boddie) (Lepidoptera: Noctuidae), egg numbers and damage rates were largely unaffected by the presence or absence of a border, although in one instance egg numbers were significantly lower in fields with borders. Overall, foliage-dwelling predaceous arthropods were somewhat more abundant in fields with borders than in fields without borders. Tarnished plant bugs, Lygus lineolaris (Palisot de Beauvois) (Heteroptera: Miridae) were significantly more abundant in fields with borders, but stink bugs, Acrosternum hilare (Say), and Euschistus servus (Say) (Hemiptera: Pentatomidae) numbers appeared to be largely unaffected by border treatment. Few taxa clearly exhibited distributional edge effects relative to the presence or absence of border vegetation. Field borders like those examined in this study likely will have little impact on insect pest management in cotton under current insect management regimens

On the origin and evolution of the material in 67P/Churyumov-Gerasimenko

International audiencePrimitive objects like comets hold important information on the material that formed our solar system. Several comets have been visited by spacecraft and many more have been observed through Earth- and space-based telescopes. Still our understanding remains limited. Molecular abundances in comets have been shown to be similar to interstellar ices and thus indicate that common processes and conditions were involved in their formation. The samples returned by the Stardust mission to comet Wild 2 showed that the bulk refractory material was processed by high temperatures in the vicinity of the early sun. The recent Rosetta mission acquired a wealth of new data on the composition of comet 67P/Churyumov-Gerasimenko (hereafter 67P/C-G) and complemented earlier observations of other comets. The isotopic, elemental, and molecular abundances of the volatile, semi-volatile, and refractory phases brought many new insights into the origin and processing of the incorporated material. The emerging picture after Rosetta is that at least part of the volatile material was formed before the solar system and that cometary nuclei agglomerated over a wide range of heliocentric distances, different from where they are found today. Deviations from bulk solar system abundances indicate that the material was not fully homogenized at the location of comet formation, despite the radial mixing implied by the Stardust results. Post-formation evolution of the material might play an important role, which further complicates the picture. This paper discusses these major findings of the Rosetta mission with respect to the origin of the material and puts them in the context of what we know from other comets and solar system objects

sj-jpg-4-cpc-10.1177_10556656221141188 - Supplemental material for Establishing a Clinical Protocol for Velopharyngeal MRI and Interpreting Imaging Findings

Supplemental material, sj-jpg-4-cpc-10.1177_10556656221141188 for Establishing a Clinical Protocol for Velopharyngeal MRI and Interpreting Imaging Findings by Jamie L. Perry, Taylor D. Snodgrass, Imani R. Gilbert, Bradley P. Sutton, Adriane L. Baylis, Erica M. Weidler, Raymond W. Tse, Stacey L. Ishman and Thomas J. Sitzman in The Cleft Palate Craniofacial Journal</p

sj-jpg-3-cpc-10.1177_10556656221141188 - Supplemental material for Establishing a Clinical Protocol for Velopharyngeal MRI and Interpreting Imaging Findings

Supplemental material, sj-jpg-3-cpc-10.1177_10556656221141188 for Establishing a Clinical Protocol for Velopharyngeal MRI and Interpreting Imaging Findings by Jamie L. Perry, Taylor D. Snodgrass, Imani R. Gilbert, Bradley P. Sutton, Adriane L. Baylis, Erica M. Weidler, Raymond W. Tse, Stacey L. Ishman and Thomas J. Sitzman in The Cleft Palate Craniofacial Journal</p

sj-jpg-2-cpc-10.1177_10556656221141188 - Supplemental material for Establishing a Clinical Protocol for Velopharyngeal MRI and Interpreting Imaging Findings

Supplemental material, sj-jpg-2-cpc-10.1177_10556656221141188 for Establishing a Clinical Protocol for Velopharyngeal MRI and Interpreting Imaging Findings by Jamie L. Perry, Taylor D. Snodgrass, Imani R. Gilbert, Bradley P. Sutton, Adriane L. Baylis, Erica M. Weidler, Raymond W. Tse, Stacey L. Ishman and Thomas J. Sitzman in The Cleft Palate Craniofacial Journal</p

sj-docx-7-cpc-10.1177_10556656221141188 - Supplemental material for Establishing a Clinical Protocol for Velopharyngeal MRI and Interpreting Imaging Findings

Supplemental material, sj-docx-7-cpc-10.1177_10556656221141188 for Establishing a Clinical Protocol for Velopharyngeal MRI and Interpreting Imaging Findings by Jamie L. Perry, Taylor D. Snodgrass, Imani R. Gilbert, Bradley P. Sutton, Adriane L. Baylis, Erica M. Weidler, Raymond W. Tse, Stacey L. Ishman and Thomas J. Sitzman in The Cleft Palate Craniofacial Journal</p

sj-tgz-6-cpc-10.1177_10556656221141188 - Supplemental material for Establishing a Clinical Protocol for Velopharyngeal MRI and Interpreting Imaging Findings

Supplemental material, sj-tgz-6-cpc-10.1177_10556656221141188 for Establishing a Clinical Protocol for Velopharyngeal MRI and Interpreting Imaging Findings by Jamie L. Perry, Taylor D. Snodgrass, Imani R. Gilbert, Bradley P. Sutton, Adriane L. Baylis, Erica M. Weidler, Raymond W. Tse, Stacey L. Ishman and Thomas J. Sitzman in The Cleft Palate Craniofacial Journal</p