Analysis of Coaxial Soil Cell in Reflection and Transmission

Accurate measurement of moisture content is a prime requirement in hydrological, geophysical and biogeochemical research as well as for material characterization and process control. Within these areas, accurate measurements of the surface area and bound water content is becoming increasingly important for providing answers to many fundamental questions ranging from characterization of cotton fiber maturity, to accurate characterization of soil water content in soil water conservation research to bio-plant water utilization to chemical reactions and diffusions of ionic species across membranes in cells as well as in the dense suspensions that occur in surface films. In these bound water materials, the errors in the traditional time-domain-reflectometer, “TDR”, exceed the range of the full span of the material’s permittivity that is being measured. Thus, there is a critical need to re-examine the TDR system and identify where the errors are to direct future research. One promising technique to address the increasing demands for higher accuracy water content measurements is utilization of electrical permittivity characterization of materials. This technique has enjoyed a strong following in the soil-science and geological community through measurements of apparent permittivity via time-domain-reflectometery as well in many process control applications. Recent research however, is indicating a need to increase the accuracy beyond that available from traditional TDR. The most logical pathway then becomes a transition from TDR based measurements to network analyzer measurements of absolute permittivity that will remove the adverse effects that high surface area soils and conductivity impart onto the measurements of apparent permittivity in traditional TDR applications. This research examines the theoretical basis behind the coaxial probe, from which the modern TDR probe originated from, to provide a basis on which to perform absolute permittivity measurements. The research reveals currently utilized formulations in accepted techniques for permittivity measurements which violate the underlying assumptions inherent in the basic models due to the TDR acting as an antenna by radiating energy off the end of the probe, rather than returning it back to the source as is the current assumption. To remove the effects of radiation from the experimental results obtain herein, this research utilized custom designed coaxial probes of various diameters and probe lengths by which to test the coaxial cell measurement technique for accuracy in determination of absolute permittivity. In doing so, the research reveals that the basic models available in the literature all omitted a key correction factor that is hypothesized by this research as being most likely due to fringe capacitance. To test this theory, a Poisson model of a coaxial cell was formulated to calculate the effective extra length provided by the fringe capacitance which is then used to correct the experimental results such that experimental measurements utilizing differing coaxial cell diameters and probe lengths, upon correction with the Poisson model derived correction factor, all produce the same results thereby lending support for the use of an augmented measurement technique, described herein, for measurement of absolute permittivity, as opposed to the traditional TDR measurement of apparent permittivity

Recovery and Utilization of Deceased Donor Kidneys from Small Pediatric Donors

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/72146/1/j.1600-6143.2006.01353.x.pd

A prospective, randomized trial of complete avoidance of steroids in liver transplantation with follow‐up of over 7 years

Objectives Steroids are a mainstay of treatment in orthotopic liver transplantation ( OLT ) and are associated with significant morbidity. This trial was conducted to assess the efficacy of steroids avoidance. Methods Patients undergoing OLT between June 2002 and April 2005 were entered into a prospective, randomized trial of complete steroids avoidance and followed until November 2011. Recipients received either standard therapy ( n = 50) or complete steroids avoidance ( n = 50). Analyses were performed on an intention‐to‐treat basis. The mean follow‐up of all recipients was 2095 ± 117 days. Sixteen (32%) recipients randomized to the steroids avoidance group ultimately received steroids for clinical indications. Results Incidences of diabetes and hypertension prior to or after OLT were similar in both groups, as was the incidence of rejection. Patient and graft survival rates at 1, 3 and 5 years were lower in the steroids avoidance group than in the standard therapy group (patient survival: 1‐year, 80% versus 86%; 3‐year, 68% versus 76%; 5‐year, 60% versus 72%; graft survival: 1‐year, 76% versus 76%; 3‐year, 64% versus 74%; 5‐year, 56% versus 72%), but the differences were not statistically different. Conclusions Complete steroids avoidance provides liver transplant recipients with minimal benefit and appears to result in a concerning trend towards decreased graft and recipient survival. The present data support the use of at least a short course of steroids after liver transplantation.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/97180/1/hpb576.pd

F.A.R.O.G. FORUM, Vol. 2 No. 9

https://digitalcommons.library.umaine.edu/francoamericain_forum/1008/thumbnail.jp

The clinical presentation and prognostic factors for intrahepatic and extrahepatic cholangiocarcinoma in a tertiary care centre

Aliment Pharmacol Ther   31 , 625–633The incidence of cholangiocarcinoma is rising. Accurate predictors of survival at diagnosis are not well defined.To clarify the clinical presentation and prognostic factors of intrahepatic cholangiocarcinoma and extrahepatic cholangiocarcinoma in a contemporary cohort of patients.Records for consecutive patients at the University of Michigan hospital diagnosed with cholangiocarcinoma between January 2003 and April 2008 were reviewed.In all, 136 patients had cholangiocarcinoma (79 intra- and 57 extrahepatic cholangiocarcinoma). Median survival was 27.3 months–25.8 months for intrahepatic cholangiocarcinoma and 30.3 months for extrahepatic cholangiocarcinoma. Independent predictors of mortality at presentation on multivariate analysis were elevated bilirubin level (HR 1.04, 95%CI 1.01–1.07), CA 19-9 levels >100 U/mL (HR 1.90, 95%CI 1.17–3.08) and stage of disease (HR 1.51, 95%CI 1.16–1.96). After adjusting for baseline prognostic factors, surgical therapy was associated with improved survival (HR 0.48; 95% CI 0.26–0.88). There were no significant differences regarding clinical presentation, disease stage ( P  = 0.98), and survival ( P  = 0.51) between intra- and extrahepatic cholangiocarcinoma.Survival for cholangiocarcinoma remains poor with no significant difference in outcomes between intra- and extrahepatic cholangiocarcinoma. Stage of disease, bilirubin level and CA 19-9 level are important prognostic factors at presentation. Surgical therapy provides similar efficacy for both tumours when adjusted for other prognostic variables.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/79101/1/j.1365-2036.2009.04218.x.pd

Synergistic effects between analogs of DNA and RNA improve the potency of siRNA-mediated gene silencing

We report that combining a DNA analog (2′F-ANA) with rigid RNA analogs [2′F-RNA and/or locked nucleic acid (LNA)] in siRNA duplexes can produce gene silencing agents with enhanced potency. The favored conformations of these two analogs are different, and combining them in a 1–1 pattern led to reduced affinity, whereas alternating short continuous regions of individual modifications increased affinity relative to an RNA:RNA duplex. Thus, the binding affinity at key regions of the siRNA duplex could be tuned by changing the pattern of incorporation of DNA-like and RNA-like nucleotides. These heavily or fully modified duplexes are active against a range of mRNA targets. Effective patterns of modification were chosen based on screens using two sequences targeting firefly luciferase. We then applied the most effective duplex designs to the knockdown of the eIF4E binding proteins 4E-BP1 and 4E-BP2. We identified modified duplexes with potency comparable to native siRNA. Modified duplexes showed dramatically enhanced stability to serum nucleases, and were characterized by circular dichroism and thermal denaturation studies. Chemical modification significantly reduced the immunostimulatory properties of these siRNAs in human peripheral blood mononuclear cells

Risk Factors for Urinary Complications After Renal Transplantation

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/73788/1/j.1600-6143.2007.01790.x.pd

A Francisella Mutant in Lipid A Carbohydrate Modification Elicits Protective Immunity

Francisella tularensis (Ft) is a highly infectious Gram-negative bacterium and the causative agent of the human disease tularemia. Ft is designated a class A select agent by the Centers for Disease Control and Prevention. Human clinical isolates of Ft produce lipid A of similar structure to Ft subspecies novicida (Fn), a pathogen of mice. We identified three enzymes required for Fn lipid A carbohydrate modifications, specifically the presence of mannose (flmF1), galactosamine (flmF2), or both carbohydrates (flmK). Mutants lacking either galactosamine (flmF2) or galactosamine/mannose (flmK) addition to their lipid A were attenuated in mice by both pulmonary and subcutaneous routes of infection. In addition, aerosolization of the mutants (flmF2 and flmK) provided protection against challenge with wild-type (WT) Fn, whereas subcutaneous administration of only the flmK mutant provided protection from challenge with WT Fn. Furthermore, infection of an alveolar macrophage cell line by the flmK mutant induced higher levels of tumor necrosis factor-α (TNF-α) and macrophage inhibitory protein-2 (MIP-2) when compared to infection with WT Fn. Bone marrow–derived macrophages (BMMø) from Toll-like receptor 4 (TLR4) and TLR2/4 knockout mice infected with the flmK mutant also produced significantly higher amounts of interleukin-6 (IL-6) and MIP-2 than BMMø infected with WT Fn. However, production of IL-6 and MIP-2 was undetectable in BMMø from MyD88−/− mice infected with either strain. MyD88−/− mice were also susceptible to flmK mutant infection. We hypothesize that the ability of the flmK mutant to activate pro-inflammatory cytokine/chemokine production and innate immune responses mediated by the MyD88 signaling pathway may be responsible for its attenuation, leading to the induction of protective immunity by this mutant

Nucleoside triphosphate diphosphohydrolase-1 ectonucleotidase is required for normal vas deferens contraction and male fertility through maintaining P2X1 receptor function

In this work, we report that Entpd1(-/-) mice, deficient for the ectonucleotidase nucleoside triphosphate diphosphohydrolase-1 (NTPDase1), produce smaller litters (27% reduction) compared with wild-type C57BL6 animals. This deficit is linked to reduced in vivo oocyte fertilization by Entpd1(-/-) males (61 ± 11% versus 88 ± 7% for Entpd1(+/+)). Normal epididymal sperm count, spermatozoa morphology, capacitation, and motility and reduced ejaculated sperm number (2.4 ± 0.5 versus 3.7 ± 0.4 million for Entpd1(+/+)) pointed to vas deferens dysfunction. NTPDase1 was localized by immunofluorescence in the tunica muscularis of the vas deferens. Its absence resulted in a major ATP hydrolysis deficiency, as observed in situ by histochemistry and in primary smooth muscle cell cultures. In vitro, Entpd1(-/-) vas deferens displayed an exacerbated contraction to ATP, a diminished response to its non-hydrolysable analog αβMeATP, and a reduced contraction to electrical field stimulation, suggesting altered P2X1 receptor function with a propensity to desensitize. This functional alteration was accompanied by a 3-fold decrease in P2X1 protein expression in Entpd1(-/-) vas deferens with no variation in mRNA levels. Accordingly, exogenous nucleotidase activity was required to fully preserve P2X1 receptor activation by ATP in vitro. Our study demonstrates that NTPDase1 is required to maintain normal P2X1 receptor functionality in the vas deferens and that its absence leads to impaired peristalsis, reduced spermatozoa concentration in the semen, and, eventually, reduced fertility. This suggests that alteration of NTPDase1 activity affects ejaculation efficacy and male fertility. This work may contribute to unveil a cause of infertility and open new therapeutic potentials

Le FORUM, Vol. 39 No. 4

https://digitalcommons.library.umaine.edu/francoamericain_forum/1047/thumbnail.jp