Autocrine effects of nitric oxide on HCO3- transport by rat thick ascending limb

Autocrine effects of nitric oxide on HCO3- transport by rat thick ascending limb.BackgroundIn vivo and in vitro studies have shown that nitric oxide (NO) is an important modulator of transport processes along the nephron. The thick ascending limb (TAL) plays a significant role in the urine-concentrating mechanism and in the maintenance of acid/base balance.MethodsTALs from male Sprague-Dawley rats were isolated and perfused, and net bicarbonate flux (JHCO3-) was determined.ResultsIn perfused TALs, 0.5 mmol/L L-arginine (L-Arg), the substrate for NO synthase, significantly lowered JHCO3- from 35.4 ± 4.6 to 23.2 ± 2.9 pmol · mm-1· min-1, a decrease of 36.9 ± 11.6% (P < 0.025). D-Arg (0.5 mmol/L) had no effect on JHCO3- (N = 7). In the presence of 5 mmol/L L-NAME, an NO synthase (NOS) inhibitor, the addition of L-Arg did not affect TAL JHCO3- (43.4 ± 4.4 vs. 44.6 ± 5.0 pmol · mm-1· min-1). L-NAME alone (5 mmol/L) did not affect TAL JHCO3-. After removing L-Arg from the bath, JHCO3- increased from 26.2 ± 3.9 to 34.8 ± 3.2 pmol · mm-1· min-1 (P < 0.01), indicating no cytotoxicity of NO. We next investigated the effect of cGMP analogues on TAL JHCO3-. 8-Br-cGMP (50 μmol/L) and db-cGMP (50 μmol/L) significantly decreased JHCO3- by 26.3 ± 9.1% and 35.1 ± 11.6%, respectively. In the presence of cGMP (50 μmol/L), the addition of L-Arg had no effect on JHCO3-. In the presence of KT-5823 (2 μmol/L), a protein kinase G inhibitor, the addition of L-Arg did not change TAL JHCO3- (N = 5).ConclusionsWe conclude that (1) endogenously produced NO inhibits TAL JHCO3- in an autocrine manner, (2) cGMP mediates all of the effects of NO, and (3) this effect is mediated by protein kinase G activation

Mass and heat integration in ethanol production mills for enhanced process efficiency and exergy-based renewability performance

This paper presents the process design and assessment of a sugarcane-based ethanol production system that combines the usage of both mass and heat integration (pinch analysis) strategies to enhance the process efficiency and renewability performance. Three configurations were analyzed: (i) Base case: traditional ethanol production (1G); (ii) mass-integrated (1G2G); and (iii) mass and heat-integrated system (1G2G-HI). The overall assessment of these systems was based on complementary approaches such as mass and mass-heat integration, energy and exergy analysis, exergy-based greenhouse gas (GHG) emissions, and renewability exergy criteria. The performances of the three cases were assessed through five key performance indicators (KIPs) divided into two groups: one is related to process performance, namely, energy efficiency, exergy efficiency, and average unitary exergy cost (AUEC), and the other one is associated to environmental performance i.e., exergy-based CO2-equation emissions and renewability exergy index. Results showed a higher exergy efficiency of 50% and the lowest AUEC of all the systems (1.61 kJ/kJ) for 1G2G-HI. Furthermore, the destroyed exergy in 1G2G-HI was lower by 7% and 9% in comparison to the 1G and 1G2G cases, respectively. Regarding the exergy-based GHG emissions and renewability performance (lambda(index)), the 1G2G-HI case presented the lowest impacts in terms of the CO2-equivalent emissions (94.10 gCO(2)-eq/MJ products), while lambda(index) was found to be environmentally unfavorable (lambda = 0.77). However, lambda(index) became favorable (lambda > 1) when the useful exergy of the byproducts was considered710sem informaçãosem informaçã

Extending Water Resources Performance Metrics to River Ecosystems

A persistent challenge in integrated water management is the ability to accurately evaluate human and ecological tradeoffs. Two-dimensional (2D) hydraulic models are frequently used to evaluate water management alternatives concerning aquatic species physical habitat needs or preferences. Recent studies have assessed the timing or duration of suitable habitat conditions, but no standardized approach exists to integrate and interpret ecohydraulic model outputs within a water management framework. Such an approach is needed to maximize the information obtained from model outputs and to facilitate communication between river scientists and water managers. This study presents a general framework to aggregate and summarize 2D hydraulic model outputs by adapting the traditional water resources metrics of reliability, resilience, vulnerability, and sustainability. Just as these metrics are typically used to quantify distinct aspects of water resources performance, applying them to ecohydraulic conditions facilitates interpretation of ecological performance and human-ecosystem water management tradeoffs. This paper examines the utility and limitations of the proposed framework and metrics in a simple application to fall-run Chinook salmon in a typical Mediterranean-montane stream

Insulin and GLP-1 infusions demonstrate the onset of adipose-specific insulin resistance in a large fasting mammal: potential glucogenic role for GLP-1.

Prolonged food deprivation increases lipid oxidation and utilization, which may contribute to the onset of the insulin resistance associated with fasting. Because insulin resistance promotes the preservation of glucose and oxidation of fat, it has been suggested to be an adaptive response to food deprivation. However, fasting mammals exhibit hypoinsulinemia, suggesting that the insulin resistance-like conditions they experience may actually result from reduced pancreatic sensitivity to glucose/capacity to secrete insulin. To determine whether fasting results in insulin resistance or in pancreatic dysfunction, we infused early- and late-fasted seals (naturally adapted to prolonged fasting) with insulin (0.065 U/kg), and a separate group of late-fasted seals with low (10 pM/kg) or high (100 pM/kg) dosages of glucagon-like peptide-1 (GLP-1) immediately following a glucose bolus (0.5g/kg), and measured the systemic and cellular responses. Because GLP-1 facilitates glucose-stimulated insulin secretion, these infusions provide a method to assess pancreatic insulin-secreting capacity. Insulin infusions increased the phosphorylation of insulin receptor and Akt in adipose and muscle of early and late fasted seals; however the timing of the signaling response was blunted in adipose of late fasted seals. Despite the dose-dependent increases in insulin and increased glucose clearance (high dose), both GLP-1 dosages produced increases in plasma cortisol and glucagon, which may have contributed to the glucogenic role of GLP-1. Results suggest that fasting induces adipose-specific insulin resistance in elephant seal pups, while maintaining skeletal muscle insulin sensitivity, and therefore suggests that the onset of insulin resistance in fasting mammals is an evolved response to cope with prolonged food deprivation

LPS-Induced Genes in Intestinal Tissue of the Sea Cucumber Holothuria glaberrima

Metazoan immunity is mainly associated with specialized cells that are directly involved with the immune response. Nevertheless, both in vertebrates and invertebrates other organs might respond to immune activation and participate either directly or indirectly in the ongoing immune process. However, most of what is known about invertebrate immunity has been restricted to immune effector cells and little information is available on the immune responses of other tissues or organs. We now focus on the immune reactions of the intestinal tissue of an echinoderm. Our study employs a non-conventional model, the echinoderm Holothuria glaberrima, to identify intestinal molecules expressed after an immune challenge presented by an intra-coelomic injection of lipopolysaccharides (LPS). The expression profiles of intestinal genes expressed differentially between LPS-injected animals and control sea water-injected animals were determined using a custom-made Agilent microarray with 7209 sea cucumber intestinal ESTs. Fifty (50) unique sequences were found to be differentially expressed in the intestine of LPS-treated sea cucumbers. Seven (7) of these sequences represented homologues of known proteins, while the remaining (43) had no significant similarity with any protein, EST or RNA database. The known sequences corresponded to cytoskeletal proteins (Actin and alpha-actinin), metabolic enzymes (GAPDH, Ahcy and Gnmt), metal ion transport/metabolism (major yolk protein) and defense/recognition (fibrinogen-like protein). The expression pattern of 11 genes was validated using semi-quantitative RT-PCR. Nine of these corroborated the microarray results and the remaining two showed a similar trend but without statistical significance. Our results show some of the molecular events by which the holothurian intestine responds to an immune challenge and provide important information to the study of the evolution of the immune response

MOGEDA : Modelo Genérico de Desensamblado Automático

El desensamblado de productos es la clave del proceso de reciclado. En este artículo se plantea el modelado del proceso de desensamblado automático de productos. Se estudian, tanto los requerimientos necesarios para poder abordar el proceso de forma automática, como las herramientas necesarias para poderlo llevar a cabo: base de conocimiento basada en modelos y técnicas de reconocimiento y localización tridimensional de objetos mediante visión artificial.Tanto los trabajos realizados como los futuros están enmarcados en el proyecto de la CICYT “Sistema Robotizado de Desensamblado Automático basado en Modelos y Visión Artificial” (TAP1999-0436)

Differential Subplastidial Localization and Turnover of Enzymes Involved in Isoprenoid Biosynthesis in Chloroplasts

Plastidial isoprenoids are a diverse group of metabolites with roles in photosynthesis, growth regulation, and interaction with the environment. The methylerythritol 4-phosphate (MEP) pathway produces the metabolic precursors of all types of plastidial isoprenoids. Proteomics studies in Arabidopsis thaliana have shown that all the enzymes of the MEP pathway are localized in the plastid stroma. However, immunoblot analysis of chloroplast subfractions showed that the first two enzymes of the pathway, deoxyxylulose 5-phosphate synthase (DXS) and reductoisomerase (DXR), can also be found in non-stromal fractions. Both transient and stable expression of GFP-tagged DXS and DXR proteins confirmed the presence of the fusion proteins in distinct subplastidial compartments. In particular, DXR-GFP was found to accumulate in relatively large vesicles that could eventually be released from chloroplasts, presumably to be degraded by an autophagy-independent process. Together, we propose that protein-specific mechanisms control the localization and turnover of the first two enzymes of the MEP pathway in Arabidopsis chloroplasts

Testing integrability with a single bit of quantum information

We show that deterministic quantum computing with a single bit (DQC1) can determine whether the classical limit of a quantum system is chaotic or integrable using O(N) physical resources, where $N$ is the dimension of the Hilbert space of the system under study. This is a square root improvement over all known classical procedures. Our study relies strictly on the random matrix conjecture. We also present numerical results for the nonlinear kicked top.Comment: Minor changes taking into account Howard Wiseman's comment: quant-ph/0305153. Accepted for publication in Phys. Rev.