Normal Steady State Research Articles

Vanilloid receptor-1 as a regulator of gut homeostasis (MUC8P.800)

Abstract The intestinal mucosa is exposed to myriads of foreign antigens. Hence the immune responses elicited to innocuous antigens in the gut are highly regulated to avoid overt inflammation. CX3CR1hi macrophages , also known as regulatory macrophages, play a critical role in maintenance of immune homeostasis in the gut. Thus therapeutic strategies leading to increase in CX3CR1hi macrophages would be beneficial for treatment of inflammatory diseases. Our present study demonstrates that Vanilloid receptor 1 (VR1), an ion channel previously identified on sensory neurons, is specifically expressed in the CD64+CX3CR1hi macrophages in intestinal lamina propria (LP). VR1-/- mice under normal steady state conditions have significantly reduced number of CX3CR1hi macrophages as compared to wild type counterpart. This data indicates a homeostatic role of VR1 and its endogenous ligands in regulating inflammation and maintaining immune tolerance in the gut. Interestingly, engagement of VR1 by orally administering its exogenous ligand Capsaicin (CP), the pungent component of chili peppers, increases the frequency of CD64+CX3CR1hi macrophages in LP. Furthermore we have shown that CP administration plays a key role in promotion of tolerance via the induction of immune-suppressive CD4+IL10+ IFN- γ+FoxP3- Tr1 cells in IL27 dependent manner. The therapeutic relevance of this phenomenon is highlighted by our study that oral administration of CP to NOD mice provides protection from Type 1 diabetes.

Integral region-based covariance tracking with occlusion detection

Covariance tracking has achieved impressive successes in recent years due to its competent region covariance-based feature descriptor. Although adopt fast integral image computation, covariance tracking's brute-force search strategy is still inefficient and it possibly leads to inconsecutive tracking trajectory and distraction. In this work, a generalized, adaptive covariance tracking approach with novel integral region computation and occlusion detection is proposed. The integral region is much faster than integral image and adaptive to the tracking target and tracking condition. The adaptive search window can be adjusted dynamically by simple occlusion detection. The integral image and the global covariance tracking can be seen just a special case of integral region and the proposed approach, respectively. The proposed approach unifies the local and global search strategies in an elegant way and smoothly switches between them according to the tracking conditions (i.e. occlusion distraction or sudden motion) which are judged by occlusion detector. It gets much better efficiency, robustness of distraction, and stable trajectory by local search in normal steady state, while obtains more abilities for occlusion and re-identification by enlarged search window (until to global search) in abnormal situation at the same time. Our approach shows excellent target representation ability, faster speed, and more robustness, which has been verified on some video sequences.

Bulk and isotopic characterization of biogenic CO2 sources and variability in the Weyburn injection area

To help evaluate surface monitoring tools for Weyburn, it is important to establish ranges of natural variation, and signal to noise ratio (SNR) of MMV tools in their intended setting. This study took place at three sites, two of which were in the injection field. For six months, we measured parameters at various temporal scales from half-hourly (CO2 surface flux and meteorology), to monthly (soil gas CO2 and δ13CO2), to bi-monthly (soil gas CO142), to compare SNRs of promising MMV techniques for Weyburn. Our summary of findings is as follows:1.All observed data fell within the range of values considered normal for Weyburn and for proximal control sites such as the Minard farm.2.High temporal variation in CO2 surface fluxes were observed. Lower atmospheric CO2 concentrations were also highly variant, and coupled with abiotic factors. A modelling strategy was able to reduce observed variability by 80–95%. When used together, soil CO2 surface flux + modelling methods can produce high SNRs for leak detection.3.Temporal variability in soil profile CO2 concentration was controlled by soil gas diffusivity (soil wetting/drying) and not biological production. Despite various sources of noise, we conclude that soil gas bulk CO2 investigations can still be useful for MMV.4.There were many possible influences on δ13CO2, including biological variation, normal steady and non-steady state physical transport (several ‰), spatial differences (0–3‰), and temporal fluctuations (0–3‰). The effects of these influences are cumulative. Relative to this background variation, the Cenovus-source δ13CO2 is not highly differentiated, and δ13CO2 is not a robust tracer.5.High precision radiocarbon soil profile data indicates that CO2 produced within the soil profile is modern and its average age is less than decades old. This age is consistent with other studies, and recent Kerr investigations (Trium, 2011). There was a tendency towards older CO142 production with increasing depth. There is a marked differentiation in CO142 signature from deep gases, and low variation. Radiocarbon is a very promising tracer for Weyburn with high SNR.

Bifurcating response to hemorrhage in a population of mathematical models of the circulation

Hemorrhage experiments in humans have produced a variety of outcomes, ranging from circulatory compensation to decompensation from a stable steady state. We have constructed model populations by parameter sampling from distributions drawn from the literature. These populations display normal steady state circulatory function, but show a bifurcated response to hemorrhage by or derived via a calibration algorithm. Each model in the population is itself deterministic. After calibrating the population to simulate ordinary ranges in a variety of circulatory outputs, the response to hemorrhage in mean arterial pressure and cardiac output was similar to that seen in a human population. Individuals were assumed to be entering cardiovascular shock provided MAP decreased at least 15 mmHg. This definition produced a meta-output, the circulatory decompensation rate (CDR), that could be compared against that seen in human hemorrhage studies. Our population showed 76% decompensation, comparable to 78% in human studies. Furthermore, applying trained learning machines to analysis of parameters and variables before hemorrhage allows the construction susceptibility rubrics capable of high value prediction of decompensation. Supported by NSF EPSCoR and 1T32HL105324.

Influence of Renal Sympathetic Nerve Activity on Sodium Excretion during Sodium Restriction

Sodium restriction leads to a decrease in blood pressure which causes a rise in renal sympathetic nerve activity (RSNA). An increased RSNA acts directly on the kidneys to increase renin secretion, sodium reabsorption, and vascular resistance. We hypothesize that during sodium restriction an increased RSNA contributes to decreased sodium excretion. To test this hypothesis, we used a mathematical model of a cardiovascular system with two kidneys. We performed three simulations where we decreased the normal sodium intake 50% for ten days: (1) When both kidneys are innervated, our model predicted that within a few days, the decrease in renal sodium excretion matched the decrease in sodium intake. (2) We fixed both kidneys’ RSNA at a normal steady state value. With bilaterally RSNA-fixed conditions sodium excretion stabilizes at the same value as in the normal condition suggesting that RSNA does not affect renal sodium excretion. However it is possible that other compensatory mechanisms mask the influence of RSNA when both kidneys’ RSNA are fixed. (3) Therefore, we fixed the left kidney's RSNA so that it could not increase, while the right kidney's RSNA remained intact and able to increase. Because both kidneys were exposed to the same arterial pressures and hormonal effects, the difference in renal sodium excretion between the intact and RSNA-fixed kidney was due to RSNA's effect. In this simulation, the RSNA intact kidney excreted less sodium than the RSNA fixed kidney, predicting that increased RSNA helps to decrease renal sodium excretion during restriction of sodium intake. Supported by NSF EPSCoR 0903787

Unexpected Role for Properdin in Complement C3 Glomerulopathies

The complement system is a major component of innate immunity and plays a key role in our defense against foreign pathogens.[1][1] In normal steady state conditions, the complement system has no significant biologic activity. There are three main pathways to generate biologic activity by initiation

Tle4 Is Critical for Proper B- Cell Differentiation and Maintenance of the Murine Bone Marrow Niche

AbstractAbstract 1202Transducin-like/Enhancer of Split 4 (TLE4), a homolog of the master developmental regulator in Drosophila, Groucho, is a co repressor previously described by our group as the putative tumor suppressor lost in a subset of t(8:21) AML patients also harboring 9q deletion. TLE4 has been found to be of fundamental importance in the repressive function of multiple highly conserved transcriptional complexes, including Hes1, Tcf/Lef, CSL, Runx1-3, and Pax5, all of which have been shown to be intimately connected to normal steady state hematopoiesis and deregulated in malignancy. Owing to its deletion in leukemia and its ability to confer functionality to a variety of signaling networks, our lab sought to investigate its role in hematopoiesis by generating a murine knockout model for Tle4.While normal at birth, within 2–3 weeks of age knockout (KO) animals become runted and eventually moribund by the time of weaning. Gross examination of the spleen and thymus in 3 week old animals reveals significant atrophy of these organs with severe abnormalities in normal tissue architecture. Tle4−/− mice lack clear demarcations between medullary and cortical regions of the thymus, in addition to having a significant increase in apoptosis seen via TUNEL staining. FACS analysis of the thymus shows CD4/CD8 double positive cells are heavily reduced in KOs, with an increase in both single positive mature populations. Additionally, there is a partial, but not complete, block in T cell progenitor development through TCR rearrangement (DN2-DN3 stages). Structural defects are seen in the spleen as well, with a failure in the formation of follicular zones. B cells are significantly reduced with an increase in CD11b+ cells in the spleen, in addition to a shift in the percentages of B1, B2, and marginal zone B cells in some animals. Histological examination of the long bones reveals dramatic abnormalities, both in hematopoietic and bone lineages. Tle4−/− mice exhibit a reduction in calcified bone, a dysplastic and reduced hypertrophic zone, and reabsorption of the trabecular region. These mice also have a gradual clearing of the marrow itself, with 2 week old animals first showing evidence of cytopenia that then progresses to full marrow failure by 3–3.5 weeks of age. The bone marrow exhibits a marked leukocytopenia, with a clear B lymphocytopenia as in the spleen. Furthermore, within the bone marrow, there is an increase in the number of CD4 and decrease in the number of CD8 T cells. ProB staging of developing B cells also trends towards a partial arrest in the transitions from the A through C fractions. When analyzed for progenitor populations, KO mice show severe reductions in the number of common lymphoid progenitors, while myeloid progenitors show no particular shifts in population frequency. Finally, there is a significant decrease in HSCs, defined as lin-Sca1+Ckit++ (LSK).In order to assess whether the hematological phenotype observed in these mice are of a cell intrinsic or extrinsic nature, transplants were performed using embryonic day 13.5 fetal liver and 2 week old bone marrow. Analysis of recipient animals 16 weeks after transplant revealed leukocytopenia with a specific reduction in B cells in the blood, however the T cell and LSK defects seen in donor animals was not observed. Furthermore, when LSK CD34+ Flt3+ or – cells from KO or WT 2 week old animals were plated on OP9 cells over-expressing Deltex1 or GFP, there were no defects in T, B, or CD11b+ cell production.The unique spectrum of phenotypic consequences concomitant to Tle4 deletion argues for a complex yet fundamental role in the maintenance of the hematopoietic niche. As illustrated by the ability to recapitulate some yet not all of the KO hematological aberrations in transplants, it appears that Tle4's involvement in lineage commitment is heterotypic in nature, an unsurprising finding considering its direct involvement in multiple highly conserved signaling pathways. Considering its principal role in those pathways, continued efforts to investigate the role the TLE family of corepressors play in the bone marrow niche may prove vital in reworking our paradigms for both normal and malignant hematopoiesis. [Display omitted] [Display omitted] Disclosures:No relevant conflicts of interest to declare.

On the Stability of a Four Species Syn Eco-System with Commensal Prey-Predator Pair with Prey-Predator Pair of Hosts-VI (Normal Steady State)

The present paper is devoted to an investigation on a Four Species $(S_1, S_2, S_3, S_4)$ Syn Eco-System with Commensal Prey-Predator pair with Prey-Predator pair of Hosts (Normal Steady state). The System comprises of a Prey $(S_1),$ a Predator $(S_2)$ that survives upon $S_1,$ two Hosts $S_3$ and $S_4$ for which $S_1, S-2$ are Commensal respectively i.e., $S_3$ and $S_4$ benefit $S_1 and $S_2$ respectively, without getting effected either positively or adversely. Further $S_3$ is Prey for $S_4$ and $S_4$ is Predator for $S_3.$ The pair $(S_1, S_2)$ may be referred as 1st level Prey-Predator and the pair $(S_3, S_4)$ the 2nd level Prey-Predator. The model equations of the system constitute a set of four first order non-linear ordinary differential coupled equations. In all, there are sixteen equilibrium points. Criteria for the asymptotic stability of one of these sixteen equilibrium points : Normal Steady State is established. The system would be stable if all the characteristic roots are negative, in case they are real, and have negative real parts, in case they are complex. The linearized equations for the perturbations over the equilibrium points are analyzed to establish the criteria for stability and the trajectories are illustrated. Keywords: Commensal; Eco-System; Equillibrium point; Host; Prey; Predator; Quasi-linearization; Stable; Trajectories. 2010 Mathematics Subject Classification: 92D25; 92D40.

Fault Diagnosis of Generation IV Nuclear HTGR Components Using the Enthalpy-Entropy Graph Approach

Fault diagnosis (FD) is an important component in modern nuclear power plant (NPP) supervision to improve safety, reliability, and availability. In this regard, a significant amount of experience has been gained in FD of generation II and III water-cooled nuclear energy systems through active research. However, new energy conversion methodologies as well as advances in reactor and component technology support the study of different FD methods in modern NPPs. This paper presents the application of the enthalpy-entropy (h-s) graph for FD of generation IV nuclear high temperature gas-cooled reactor (HTGR) components. The h-s graph is adapted for fault signature generation by comparing actual operating plant graphs with reference models. Multiple input feature sets (patterns) are generated for the fault classification algorithm based on the error, area, and direction of the fault residuals. The effectiveness of the FD method is demonstrated by classifying 24 non-critical single faults in the main power system of the Pebble Bed Modular Reactor (PBMR) during normal steady state operation as well as load following of the plant. Reference and fault data are calculated for the thermo-hydraulic network by means of a simulation model in Flownex ® Nuclear. The results show that the proposed FD method produces different uncorrelated fault signatures for all the examined fault conditions.

17β-Estradiol Is Required for the Sexually Dimorphic Effects of Repeated Binge-Pattern Alcohol Exposure on the HPA Axis during Adolescence

Alcohol consumption during adolescence has long-term sexually dimorphic effects on anxiety behavior and mood disorders. We have previously shown that repeated binge-pattern alcohol exposure increased the expression of two critical central regulators of stress and anxiety, corticotrophin-releasing hormone (CRH) and arginine vasopressin (AVP), in adolescent male rats. By contrast, there was no effect of alcohol on these same genes in adolescent females. Therefore, we tested the hypothesis that 17β-estradiol (E2), the predominant sex steroid hormone in females, prevents alcohol-induced changes in CRH and AVP gene expression in the paraventricular nucleus (PVN) of the hypothalamus. To test this hypothesis, postnatal day (PND) 26 females were ovariectomized and given E2 replacement or cholesterol as a control. Next, they were given an alcohol exposure paradigm of 1) saline alone, 2) acute (single dose) or 3) a repeated binge-pattern. Our results showed that acute and repeated binge-pattern alcohol treatment increased plasma ACTH and CORT levels in both E2- and Ch-treated groups, however habituation to repeated binge-pattern alcohol exposure was evident only in E2-treated animals. Further, repeated binge-pattern alcohol exposure significantly decreased CRH and AVP mRNA in Ch-, but not E2-treated animals, which was consistent with our previous observations in gonad intact females. We further tested the effects of E2 and alcohol treatment on the activity of the wild type CRH promoter in a PVN-derived neuronal cell line. Alcohol increased CRH promoter activity in these cells and concomitant treatment with E2 completely abolished the effect. Together our data suggest that E2 regulates the reactivity of the HPA axis to a repeated stressor through modulation of the habituation response and further serves to maintain normal steady state mRNA levels of CRH and AVP in the PVN in response to a repeated alcohol stressor.

Use of Genetically Encoded Photoactivable Cross-Linking Molecules to Probe NaV Channel Fast Inactivation

Fast inactivation in voltage-gated sodium channels requires efficient and rapidly reversible conformational changes in the cytoplasmic linker between domains III and IV (DIII-IV) and their putative receptor in the pore region of the channel. Introduced or acquired mutations in this complex lead to defective channel inactivation, and the resulting excessive sodium conductance can cause a myriad of pathophysiological disorders. We set out to better understand fast-inactivation by expressing voltage-gated sodium channels that carry genetically encoded orthogonal photocrosslinking (PC) amino acid molecules in the inactivation complex with the goal of capturing transient, but physiologically important complexes. PC molecules have widely been used to characterize protein-protein interactions through their ability to covalently bond with nearby molecules upon excitation by UV light. Conventional in-vivo use of PC molecules relies on their covalent attachment to introduced cysteine residues, which must be functionally tolerated and equally solvent accessible, and are limited by non-specific labelling of both target and off target proteins in the cellular environment. We have bypassed these limitations by utilizing the amber stop codon suppression system to genetically incorporate the PC unnatural amino acids (UAA) p-benzoyl-L-phenyl alanine and p-azido-L-phenylalanine into NaV1.5 channels in HEK cells. NaV1.5 channels carrying the UAA molecules showed robust expression at a number of sites in the DIII-IV linker with channel currents that displayed near normal activation, fast and steady state inactivation properties, verifying that the UAAs were well tolerated. Simultaneous patch clamp recording and UV irradiation of channels demonstrated that photo-activating the crosslinking UAA has effects on fast inactivation that are dependent upon the incorporation site and the state of the channel during UV exposure. This technique allows resolution of discrete, transient molecular conformations of the inactivation machinery that support sodium channel fast inactivation.

Analysis of operating principles with S-system models

Operating principles address general questions regarding the response dynamics of biological systems as we observe or hypothesize them, in comparison to a priori equally valid alternatives. In analogy to design principles, the question arises: Why are some operating strategies encountered more frequently than others and in what sense might they be superior? It is at this point impossible to study operation principles in complete generality, but the work here discusses the important situation where a biological system must shift operation from its normal steady state to a new steady state. This situation is quite common and includes many stress responses. We present two distinct methods for determining different solutions to this task of achieving a new target steady state. Both methods utilize the property of S-system models within Biochemical Systems Theory (BST) that steady states can be explicitly represented as systems of linear algebraic equations. The first method uses matrix inversion, a pseudo-inverse, or regression to characterize the entire admissible solution space. Operations on the basis of the solution space permit modest alterations of the transients toward the target steady state. The second method uses standard or mixed integer linear programming to determine admissible solutions that satisfy criteria of functional effectiveness, which are specified beforehand. As an illustration, we use both methods to characterize alternative response patterns of yeast subjected to heat stress, and compare them with observations from the literature.

Homeostatic interactions between the intestinal microbiome and the mucosal immune system (LL1-2)

The diverse intestinal microbiome in mammals is the product of many thousands of years of natural selection and adaptation of the enteric microflora to their luminal environment. Under normal steady state conditions, the relationship between the commensal enteric flora and their hosts is characterized by peaceful coexistence. The commensal enteric microflora sustain themselves in a variety of niches in a nutrient-rich environment while benefiting the host by various mechanisms including production of digestive enzymes and vitamins and protection against pathogenic bacterial species. Full development of a normal mucosal immune system depends on stimuli derived from the intestinal microbiome. The host utilizes several tools to impose limits on the enteric microflora, including antibacterial peptides, mucus, and secretory immunoglobulins. Continuous sampling of the enteric microflora by the host immune system is part of this process and is accomplished via the action of M (microfold) cells and mononuclear phagocytes residing in the lamina propria. Dysregulation of the normally mutualistic relationship between the host and the enteric microflora can upset the homeostatic balance and lead to serious consequences for the host. Unchecked stimulation of innate or adaptive immunity directed against components of the microflora can lead to inflammatory bowel disease. Recent technical advances in DNA sequencing technologies have led to new insights into the contribution of specific bacterial species to maintaining homeostasis at the gut mucosal interface. Manipulation of the composition of the enteric microflora has emerged as a potential approach to promoting homeostatic interactions in the gut and improving digestive health.

Prediction of internal temperature in stator winding of three-phase induction motors with ann

This paper implements an artificial neural network (ANN) model able to estimate the internal temperatures in stator winding of a squirrel-cage three-phase induction motor fed by a voltage inverter. A sinusoidal pulse-width modulation (SPWM) inverter feeding three-phase induction motors were tested up to over load. The temperatures are measured in a node of stator winding. The results show that the ANN model produces reliable estimates of interior temperature of stator winding. Through this model, it is possible to determine the temperatures in the tested motors and to analyze the influence of the fundamental frequency voltage on steady state temperatures and motor performance limitation, specifically the maximum acceptable load, so that the motor does not exceed its normal steady state temperature when is supplied by an inverter. Copyright © 2010 John Wiley & Sons, Ltd.

Light cone dynamics and reverse Kibble-Zurek mechanism in two-dimensional superfluids following a quantum quench

We study the dynamics of the relative phase of a bilayer of two-dimensional superfluids after the two superfluids have been decoupled. We find that on short time scales the relative phase shows "light cone" like dynamics and creates a metastable superfluid state, which can be supercritical. We also demonstrate similar light cone dynamics for the transverse field Ising model. On longer time scales the supercritical state relaxes to a disordered state due to dynamical vortex unbinding. This scenario of dynamically suppressed vortex proliferation constitutes a reverse-Kibble-Zurek effect. We study this effect both numerically using truncated Wigner approximation and analytically within a newly suggested time dependent renormalization group approach (RG). In particular, within RG we show that there are two possible fixed points for the real time evolution corresponding to the superfluid and normal steady states. So depending on the initial conditions and the microscopic parameters of the Hamiltonian the system undergoes a non-equilibrium phase transition of the Kosterlitz-Thouless type. The time scales for the vortex unbinding near the critical point are exponentially divergent, similar to the equilibrium case.

Characteristics of the Current Density Induced Inside a Worker Near a Neutral Ground Reactor

To reduce a high fault current, neutral ground reactors (NGR) were installed in the Korean substation. Current with several harmonic components flows in a NGR due to load unbalance in normal steady state and magnetic fields with several harmonic components are also generated around a NGR. As results of study, we found magnetic fields around a NGR in Korean substation included two harmonics, 180Hz and 540Hz. Magnetic fields of 180 Hz increased 3 times more current density inside a worker near a NGR than same magnitude magnetic fields of 60 Hz. We know a worker near a NGR may not meet ICNIRP guideline of 10(mA/) due to several harmonic components.

Defects in osteoblast function but no changes in long-term repopulating potential of hematopoietic stem cells in a mouse chronic inflammatory arthritis model

AbstractRecent studies support the notion that there is an intricate relationship between hematopoiesis and bone homeostasis in normal steady states. Using mice undergoing chronic inflammatory arthritis, we investigated the relationship between hematopoiesis and bone homeostasis in pathologic conditions. We demonstrate that mice undergoing chronic inflammatory arthritis displayed osteoporosis resulting from a severe defect in osteoblast function. Despite the defective osteoblast function, however, the hematopoietic stem cells from these mice exhibited normal properties in either long-term repopulation or cell cycling. Therefore, the bone-forming capacity of osteoblasts is distinct from their ability to maintain hematopoietic stem cells in chronic inflammatory conditions.

Increased serum OPG in atrophic nonunion shaft fractures

BackgroundBone repair alteration is hypothesized for nonunion fracture pathogenesis. Since it is involved in osteoclast regulation, the RANK/RANKL/OPG system (receptor activator of nuclear factor kB/its ligand/osteoprotegerin) may play a role.Materials and methodsSerum OPG, free RANKL, bone alkaline phosphatase (BAP), osteocalcin (OC), and urinary deoxypyridinoline (DPD) were determined in 16 male patients (20–39 years) with long bone atrophic nonunion fractures. Serum markers were also measured in 18 age-matched male controls who healed from the same type of fractures within six months, and in 14 age-matched male controls who were healing from the same fractures one month after injury. One-way ANOVA and Bonferroni’s test were used for statistical analysis.ResultsOnly OPG was significantly higher (0.56 sd 0.11 ng/ml) in the patients compared to healed (0.26 sd 0.04 ng/ml; P < 0.001) and healing (0.29 sd 0.09 ng/ml; P < 0.001) controls. The patients’ DPD levels were normal. No correlations were found between bone markers and the characteristics of the subjects in all groups.ConclusionsA normal steady state of bone metabolism seems to be present in patients with atrophic nonunion fractures, despite the high serum OPG. The reason for the inability of the patients’ OPG to inhibit osteoclastic activity is unknown. Osteoblast activity also appears normal, so another cellular source of OPG can be hypothesized.

The yeast Coq4 polypeptide organizes a mitochondrial protein complex essential for coenzyme Q biosynthesis

Coenzyme Q is a redox active lipid essential for aerobic respiration. The Coq4 polypeptide is required for Q biosynthesis and growth on non-fermentable carbon sources, however its exact function in this pathway is not known. Here we probe the functional roles of Coq4p in a yeast Q biosynthetic polypeptide complex. A yeast coq4-1 mutant harboring an E226K substitution is unable to grow on nonfermentable carbon sources. The coq4-1 yeast mutant retains significant Coq3p O-methyltransferase activity, and mitochondria isolated from coq4-1 and coq4-2 (E 121K) yeast point mutants contain normal steady state levels of Coq polypeptides, unlike the decreased levels of Coq polypeptides generally found in strains harboring coq gene deletions. Digitonin-solubilized mitochondrial extracts prepared from yeast coq4 point mutants show that Coq3p and Coq4 polypeptides no longer co-migrate as high molecular mass complexes by one- and two-dimensional Blue Native-PAGE. Similarly, gel filtration chromatography confirms that O-methyltransferase activity, Coq3p, Coq4p, and Coq7p migration are disorganized in the coq4-1 mutant mitochondria. The data suggest that Coq4p plays an essential role in organizing a Coq enzyme complex required for Q biosynthesis.

Adipose tissue gene expression in obese dogs after weight loss

Body weight (BW) mainly depends on a balance between fat storage (lipogenesis) and fat mobilization (lipolysis) in adipocytes. BW changes play a role in insulin resistance (IR), the inability of insulin target tissue to respond to physiological levels of insulin. This results in inhibition of lipogenesis and stimulation of lipolysis. Weight gain leads to IR whereas, weight loss improves insulin sensitivity (IS). The aim of this study was to evaluate the effect of weight loss and recovery of IS on the expression of genes involved in lipogenesis and lipolysis in weight losing dogs. Gene expression was studied in both subcutaneous and visceral adipose tissue. Obese dogs received a hypoenergetic low fat high protein diet (0.6 x NRC recommendation). Before and after weight loss, IS was assessed using the euglycaemic hyperinsulinaemic clamp. Gene expression of IRS-2, SREBP, intracellular insulin effectors, ACC, FAS, FABP, ADRP, PEPCK, lipogenesis key proteins, perilipin and HSL, lipolysis key proteins were quantified using real-time RT-PCR in subcutaneous and visceral fat. BW decreased from 15.2 +/- 0.5 to 11.4 +/- 0.4 kg (p < 0.05) over 78 +/- 8 days. When obese, dogs were insulin resistant. After weight loss, IS was improved. In the subcutaneous adipose tissue, the expression of only the IRS-2 was increased. In the visceral adipose tissue, the expression of the genes involved in the lipogenesis was decreased whereas one of the genes implied in the lipolysis did not change. The expression profile of genes involved in lipid metabolism, as measured after weight loss, is indicative for a lower lipogenesis after weight loss than in obese dogs. Our results also confirm dramatic differences in the lipid metabolism of visceral and subcutaneous fat. They should be completed by comparing gene expression during weight losing and normal weight steady state.