Potentiometric pH response of membranes prepared with various aminated-poly (vinyl chloride) products

The preparation and potentiometric pH response properties of membranes formulated with various aminated-poly(vinyl chloride) (PVC-NH 2 ) products are described. Products containing secondary and/or primary amino functional groups are obtained by modifying PVC with mono- and/or diamines, respectively. Blank membranes prepared with either type of aminated-polymer exhibit nearly Nernstian potentiometric pH responses over different pH ranges. In general, membranes based on diamino products exhibit pH response over a wider range (5–10.5) than membranes formulated with monoamino products (<8.0). These potentiometric results are used to estimate the basicity of the various primary and secondary amino sites in the membrane phases.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/41621/1/604_2005_Article_BF01244842.pd

Reconstruction of phyletic trees by global alignment of multiple metabolic networks

Background: In the last decade, a considerable amount of research has been devoted to investigating the phylogenetic properties of organisms from a systems-level perspective. Most studies have focused on the classification of organisms based on structural comparison and local alignment of metabolic pathways. In contrast, global alignment of multiple metabolic networks complements sequence-based phylogenetic analyses and provides more comprehensive information. Results: We explored the phylogenetic relationships between microorganisms through global alignment of multiple metabolic networks. The proposed approach integrates sequence homology data with topological information of metabolic networks. In general, compared to recent studies, the resulting trees reflect the living style of organisms as well as classical taxa. Moreover, for phylogenetically closely related organisms, the classification results are consistent with specific metabolic characteristics, such as the light-harvesting systems, fermentation types, and sources of electrons in photosynthesis. Conclusions: We demonstrate the usefulness of global alignment of multiple metabolic networks to infer phylogenetic relationships between species. In addition, our exhaustive analysis of microbial metabolic pathways reveals differences in metabolic features between phylogenetically closely related organisms. With the ongoing increase in the number of genomic sequences and metabolic annotations, the proposed approach will help identify phenotypic variations that may not be apparent based solely on sequence-based classification.National Institutes of Health (U.S.) (Grant GM081871

Polymer membrane-based ion-, gas- and bio-selective potentiometric sensors

Recent progress in the design of new polymer membrane-based potentiometric ion-, gas- and bio-selective electrodes in chemistry laboratories at the University of Michigan (Ann Arbor) is reviewed. Emphasis is placed on describing the performance of devices for measuring anions (e.g., salicylate, thiocyanate, chloride and heparin) and gases (e.g., ammonia, carbon dioxide and oxygen) in biological samples, both in vitro and in vivo. Beyond direct measurement of key ions and gases in complex matrices, some of the new membrane electrode systems reported can serve as base transducers for the development of biosensors containing integrated biological reagents, including enzymes and antibodies. New approaches for mass fabricating solid-state ion and biosensor devices as well as future directions for research in the entire field of polymer membrane sensors are also described.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/31010/1/0000685.pd

Effects of varying blood flow rate during peripheral veno-arterial extracorporeal membrane oxygen (V-A ECMO) on left ventricular function measured by two-dimensional strain

BackgroundWe evaluated the effects of varying blood flow rate during peripheral veno-arterial extracorporeal membrane oxygen (V-A ECMO) on left ventricular function measured by two-dimensional strain.MethodsAdult patients who were supported by peripheral V-A ECMO were recruited. Serial hemodynamic and cardiac performance parameters were measured by transthoracic echocardiogram within the first 48 h after implementation of V-A ECMO. Measurements at 100%, 120%, and 50% of target blood flow (TBF) were compared.ResultsA total of 54 patients were included and the main indications for V-A ECMO were myocardial infarction [32 (59.3%)] and myocarditis [6 (11.1%)]. With extracorporeal blood flow at 50% compared with 100% TBF, the mean arterial pressure was lower [66 ± 19 vs. 75 ± 18 mmHg, p &lt; 0.001], stroke volume was greater [23 (12–34) vs. 15 (8–26) ml, p &lt; 0.001], and cardiac index was higher [1.2 (0.7–1.7) vs. 0.8 (0.5–1.3) L/min/m2, p &lt; 0.001]. Left ventricular contractile function measured by global longitudinal strain improved at 50% compared with 100% TBF [−2.8 (−7.6- −0.1) vs. −1.2 (−5.2–0) %, p &lt; 0.001]. Similarly, left ventricular ejection fraction increased [24.4 (15.8–35.5) vs. 16.7 (10.0–28.5) %, p &lt; 0.001] and left ventricular outflow tract velocity time integral increased [7.7 (3.8–11.4) vs. 4.8 (2.5–8.5) cm, p &lt; 0.001]. Adding echocardiographic parameters of left ventricular systolic function to the Survival After Veno-arterial ECMO (SAVE) score had better discriminatory value in predicting eventual hospital mortality (AUROC 0.69, 95% CI 0.55–0.84, p = 0.008) and successful weaning from V-A ECMO (AUROC 0.68, 95% CI 0.53–0.83, p = 0.017).ConclusionIn the initial period of V-A ECMO support, measures of left ventricular function including left ventricular ejection fraction and global longitudinal strain were inversely related to ECMO blood flow rate. Understanding the heart-ECMO interaction is vital to interpretation of echocardiographic measures of the left ventricle while on ECMO

Segmental correction of adolescent idiopathic scoliosis by all-screw fixation method in adolescents and young adults. minimum 5 years follow-up with SF-36 questionnaire

<p>Abstract</p> <p>Background</p> <p>In our institution, the fixation technique in treating idiopathic scoliosis was shifted from hybrid fixation to the all-screw method beginning in 2000. We conducted this study to assess the intermediate -term outcome of all-screw method in treating adolescent idiopathic scoliosis (AIS).</p> <p>Methods</p> <p>Forty-nine consecutive patients were retrospectively included with minimum of 5-year follow-up (mean, 6.1; range, 5.1-7.3 years). The average age of surgery was 18.5 ± 5.0 years. We assessed radiographic measurements at preoperative (Preop), postoperative (PO) and final follow-up (FFU) period. Curve correction rate, correction loss rate, complications, accuracy of pedicle screws and SF-36 scores were analyzed.</p> <p>Results</p> <p>The average major curve was corrected from 58.0 ± 13.0° Preop to 16.0 ± 9.0° PO(<it>p </it>< 0.0001), and increased to 18.4 ± 8.6°(<it>p </it>= 0.12) FFU. This revealed a 72.7% correction rate and a correction loss of 2.4° (3.92%). The thoracic kyphosis decreased little at FFU (22 ± 12° to 20 ± 6°, (<it>p </it>= 0.25)). Apical vertebral rotation decreased from 2.1 ± 0.8 PreOP to 0.8 ± 0.8 at FFU (Nash-Moe grading, <it>p </it>< 0.01). Among total 831 pedicle screws, 56 (6.7%) were found to be malpositioned. Compared with 2069 age-matched Taiwanese, SF-36 scores showed inferior result in 2 variables: physical function and role physical.</p> <p>Conclusion</p> <p>Follow-up more than 5 years, the authors suggest that all-screw method is an efficient and safe method.</p

CD4+ T Cell-Derived IL-2 Signals during Early Priming Advances Primary CD8+ T Cell Responses

Stimulating naïve CD8+ T cells with specific antigens and costimulatory signals is insufficient to induce optimal clonal expansion and effector functions. In this study, we show that the activation and differentiation of CD8+ T cells require IL-2 provided by activated CD4+ T cells at the initial priming stage within 0–2.5 hours after stimulation. This critical IL-2 signal from CD4+ cells is mediated through the IL-2Rβγ of CD8+ cells, which is independent of IL-2Rα. The activation of IL-2 signaling advances the restriction point of the cell cycle, and thereby expedites the entry of antigen-stimulated CD8+ T-cell into the S phase. Besides promoting cell proliferation, IL-2 stimulation increases the amount of IFNγ and granzyme B produced by CD8+ T cells. Furthermore, IL-2 at priming enhances the ability of P14 effector cells generated by antigen activation to eradicate B16.gp33 tumors in vivo. Therefore, our studies demonstrate that a full CD8+ T-cell response is elicited by a critical temporal function of IL-2 released from CD4+ T cells, providing mechanistic insights into the regulation of CD8+ T cell activation and differentiation

Short-Term Exposure of Multipotent Stromal Cells to Low Oxygen Increases Their Expression of CX3CR1 and CXCR4 and Their Engraftment In Vivo

The ability of stem/progenitor cells to migrate and engraft into host tissues is key to their potential use in gene and cell therapy. Among the cells of interest are the adherent cells from bone marrow, referred to as mesenchymal stem cells or multipotent stromal cells (MSC). Since the bone marrow environment is hypoxic, with oxygen tensions ranging from 1% to 7%, we decided to test whether hypoxia can upregulate chemokine receptors and enhance the ability of human MSCs to engraft in vivo. Short-term exposure of MSCs to 1% oxygen increased expression of the chemokine receptors CX3CR1and CXCR4, both as mRNA and as protein. After 1-day exposure to low oxygen, MSCs increased in vitro migration in response to the fractalkine and SDF-1α in a dose dependent manner. Blocking antibodies for the chemokine receptors significantly decreased the migration. Xenotypic grafting into early chick embryos demonstrated cells from hypoxic cultures engrafted more efficiently than cells from normoxic cultures and generated a variety of cell types in host tissues. The results suggest that short-term culture of MSCs under hypoxic conditions may provide a general method of enhancing their engraftment in vivo into a variety of tissues