Changes In Relative Activity Research Articles

Cell Surface Biliverdin Reductase Mediates Biliverdin-induced Anti-inflammatory Effects via Phosphatidylinositol 3-Kinase and Akt

Biliverdin reductase A (BVR) catalyzes the reduction of biliverdin (BV) to bilirubin (BR) in all cells. Others and we have shown that biliverdin is a potent anti-inflammatory molecule, however, the mechanism by which BV exerts its protective effects is unclear. We describe and elucidate a novel finding demonstrating that BVR is expressed on the external plasma membrane of macrophages (and other cells) where it quickly converts BV to BR. The enzymatic conversion of BV to BR on the surface by BVR initiates a signaling cascade through tyrosine phosphorylation of BVR on the cytoplasmic tail. Phosphorylated BVR in turn binds to the p85alpha subunit of phosphatidylinositol 3-kinase and activates downstream signaling to Akt. Using bacterial endotoxin (lipopolysaccharide) to initiate an inflammatory response in macrophages, we find a rapid increase in BVR surface expression. One of the mechanisms by which BV mediates its protective effects in response to lipopolysaccharide is through enhanced production of interleukin-10 (IL-10) the prototypical anti-inflammatory cytokine. IL-10 regulation is dependent in part on the activation of Akt. The effects of BV on IL-10 expression are lost with blockade of Akt. Inhibition of surface BVR with RNA interference attenuates BV-induced Akt signaling and IL-10 expression and in vivo negates the cytoprotective effects of BV in models of shock and acute hepatitis. Collectively, our findings elucidate a potentially important new molecular mechanism by which BV, through the enzymatic activity and phosphorylation of surface BVR (BVR)(surf) modulates the inflammatory response.

Correlation of sequential nuclear imaging with interval histological changes in a porcine abdominal aortic aneurysm model

The mechanism of abdominal aortic aneurysm (AAA) formation remains incompletely described. AAA were created in the infrarenal aortas of 14 Yorkshire swine (25–35kg) using balloon dilation and luminal collagenase (8000u) and elastase (500u) perfusion. Positron emission tomography computed tomography (PET CT) was performed on post-operative days 1, 3, 7, 14, and 28 in 5 swine. Cellular uptake of 18-fluorodeoxyglucose (FDG) was quantified within AAA and sham segments of aorta using radioactive decay density within an ellipsoid volume of interest (VOI). Nine swine were euthanized at 1(n=3), 3(n=1), 7(n=1), 14(n=1), 21(n=2) and 28(n=1) days for histological analysis (H&E, Masson’s trichrome, and Verhoeff-van Giesen stain). AAA activity on day 7 (32.7%±22.3%) was significantly higher (p=0.01) than day one (−2.8±17.9%) and day 28 (1.2±22.9%). Inflammatory response, smooth muscle cell regeneration, and the appearance of hyaline matrix deposition correlate to interval FDG activity of the AAA. Extensive elastin fiber disruption was evident at all time points. FDG uptake demonstrates increased local metabolic demand following mechanical and enzyme-induced AAA formation. Regression of relative FDG uptake at 28 days suggests that elastase induced injury may not be perpetual. PET CT may provide a useful method for longitudinal noninvasive measurements within a single animal for endovascular research. Change in Relative Activity Within Ellipsoid VOIs Enclosing Porcine AAA and Sham Aorta

Autonomic nervous activity changes in relation to the reporting of subjective symptoms among male workers in an information service company

The objective of the study was to clarify the relationship between major subjective symptoms and autonomic nervous system function by power spectral analysis of heart rate variability (HRV). Short-term HRV was examined for 413 male workers in a Japanese information service company aged 19-45 years, and questionnaire survey on subjective symptoms and biochemical measurements were conducted at annual health checkup. The most prevalent subjective symptom (> or =10%) was dullness, followed by fatigue, backache, diarrhea, sleep disorder, and irritation. HRV in high frequency (HF 0.15-0.40 Hz) bands and the coefficient of variance in the electrocardiographic R-R interval (CVrr) were lower in the subjects with any of these six symptoms than in those without the symptoms. Both parameters were negatively associated with the reporting of any of the six symptoms by multiple regression analyses, controlling for the significant effects of age (HF and CVrr) and plasma cortisol levels (HF). It was suggested that the reporting of the subjective symptoms is one of good predictors for reduced parasympathetic tones.

Effect of γ-irradiation on antioxidant activity of black pepper ( Piper nigrum L.)

Antioxidant activity and EPR investigations of irradiated ground black pepper ( Piper nigrum L.) were evaluated. The black pepper was exposed to γ-irradiation at doses from 5 to 30 kGy. The effect of irradiation on antioxidant properties of black pepper extracts was investigated by radical-scavenging effect on 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals, by determination of reducing power and content of thiobarbituric acid-reactive substances. Some significant changes were observed in creation of thiobarbituric acid-reactive substances (TBARS). Difference between non-irradiated and irradiated samples at the legal European limit dose of 10 kGy reached, on average, 23% and, at the Food and Drug Administration (FDA) 30 kGy limit, 33%. Irradiation affected significantly the DPPH radical-scavenging activity and reducing power of ground black pepper extracts. The γ-radiation treatment of ground black pepper samples observed by EPR, resulted in the production of three paramagnetic species ( GI– GIII) characterized by different origin, thermal behaviour and stability. The axially symmetric EPR resonances, GI and GII, were assigned to the carbohydrate radical structures. The spin Hamiltonian parameters of GIII possessed the characteristic features of “cellulosic” radical species. The EPR measurements, performed 20 weeks after the radiation process, confirmed that temperature increase from 298 to 353 K, caused significant decrease of integral EPR signal intensity for γ-irradiated samples (∼40%), compared to the reference (non-irradiated) ground black pepper, where only 13% drop was found. Significant correlation between EPR and thiobarbituric acid methods was assessed by study of antioxidant activity changes in relation to irradiation doses and also in the case of spice storage, between EPR and reducing power methods.

Profiling treatment-specific post-translational modifications in a complex proteome with subtractive substrate phage display.

Proteolytic activation of zymogens or controlled degradation of inhibitory factors is part of a major regulatory system on the post-translational level to regulate treatment induced cellular stress responses. The identification of differential activity based substrates is thus of high interest to prioritize and validate candidate targets for drug discovery. Here we present a novel subtractive substrate phage display screening method for the selection of treatment induced post-translational peptide modifications in complex proteomes. We investigated this approach with tumor cells in response to a protease activating anticancer treatment modality using subtractive and iterative screening of cellular extracts derived from control and treated cells. Specific phage were identified that served as substrates for proteolytic activities in response to treatment related activity changes and could be distinguished from substrates for unspecific proteolytic background activities. Novel, selected peptide substrates were investigated in vitro and in vivo and showed high substrate specificity and functional biological significance.

Enzyme activity changes in relation to internal browning of Raphanus roots sown early and late

SummaryEarly sown radish seedlings were subjected to heat stress from the middle to late growth stage. Roots exhibiting internal browning (IB) were more prevalent in the susceptible cultivars whose seeds were sown early in the summer compared with those which were sown late. However, IB occurrence in the resistant ones was not nearly so marked regardless of the sowing date. In the IB susceptible cultivars, higher levels of L-phenylalanine ammonia-lyase (PAL) and polyphenol oxidase (PPO) activities were detected in roots from the early sown plot (ESP), but these enyzme inductions did not occur to a significant extent in the resistant ones. Roots suffering internal browning were also detected to have pronounced increases in ascorbate peroxidase (APX) activity, but decreases in both dehydroascorbate reductase (DHAR) and glutathione reductase (GHAR) activities. These observations strongly suggest that a decline in H2O2 decomposing capacity of the ascorbate-glutathione cycle by heat stress is responsible for the activation of H2O2 detoxyifying pathway derived from PPO.

Activity-dependent distribution of protein kinase C-delta within rat cerebellar Purkinje cells following unilateral labyrinthectomy.

Protein kinase C isoforms PKC-delta and PKC-gamma are expressed in Purkinje cells in the uvula-nodulus of the cerebellum. We examined the effect of Purkinje cell activity on the transcription, expression and intracellular distribution of PKC-delta and PKC-gamma. Relative changes in activity were induced by unilateral labyrinthectomy (UL), decreasing the activity of Purkinje cells on the side of the labyrinthectomy relative to the contralateral side with intact vestibular input. After a UL, there was decreased immunolabeling of Purkinje cell axon terminals in the ipsilateral caudal vestibular complex by antisera to PKC-delta, but not PKC-gamma. Western blots prepared from the uvula-nodulus and caudal vestibular complex showed an increase in the cytosolic PKC-delta and a decrease in membrane-associated PKC-delta in the ipsilateral uvula-nodulus 12-48 h after the UL. Hybridization histochemistry and semiquantitative reverse transcription polymerase chain reaction (RT-PCR) demonstrated no change in transcription of PKC-delta mRNA in the uvula-nodulus 1-240 h after unilateral labyrinthectomy. We conclude that both PKC-delta and PKC-gamma are constitutively expressed in Purkinje cells. The targeting of PKC-delta, but not PKC-gamma, to Purkinje neuron synaptic terminals is influenced by activity.

A modification of receptor theory. 1956.

A modification of receptor theory. 1956.

Polarized Na+/H+ exchange function is pliable in response to transepithelial gradients of propionate.

Short-chain fatty acids are produced at high concentration in the colonic lumen and stimulate electroneutral Na+ absorption by activating apical Na+/H+ exchange in colonocytes. We used an epithelial cell line derived from a human colon carcinoma (HT29-18-C1) to study activation of apical and basolateral Na+/H+ exchange by a short-chain fatty acid, propionate. Confluent cell monolayers on membrane filters were loaded with 2',7'-bis(2-carboxyethyl)-5 (and 6)-carboxyfluorescein (a fluorescent pH indicator) and intracellular pH was monitored with a digital fluorescence imaging microscope. Cells acidified by transient exposure to NH4Cl demonstrated both apical and basolateral Na+/H+ exchange. In this condition, apical Na+/H+ exchange was 50% of the total Na+/H+ exchange activity. Similar results were obtained when cells were bilaterally perfused with apical and basolateral propionate in an isosmotic medium (130 mM propionate at each membrane surface). However, apical Na+/H+ exchange was a significantly larger fraction (76%) of the total Na+/H+ exchange activity when cells were acidified by exposure to apical propionate alone. Conversely, in cells acidified by basolateral propionate alone, apical Na+/H+ exchange was 21% of the total Na+/H+ exchange activity. The change in relative activity was observed in individual cells which expressed both apical and basolateral Na+/H+ exchange and occurred rapidly (within 7 min). In the presence of transepithelial propionate gradients, all Na(+)-dependent alkalinization was sensitive to 3 microM 5-(N-ethyl-N-isopropyl)amiloride, a potent Na+/H+ exchange inhibitor. These results suggest that transepithelial gradients of short-chain fatty acids, which occur in vivo, can cause preferential activation of apical Na+/H+ exchange.

Prefrontal unit activity during associative learning in the monkey

Single unit activity was recorded from the dorsolateral prefrontal cortex of two monkeys which were trained on a stimulus-reward association task. The monkeys were trained on a reaction time task overlapped with a classical conditioning paradigm. The sequential events of the task were as follows: (1) lever pressing to start the trial; (2) presentation of a visual cue for 1 s; (3) delay period of 1 s; (4) imperative stimulus presentation; and (5) release of the lever by the animal. The visual cue signaled whether or not a drop of fruit juice would be given (its associative significance) for the animal's release response instead of signaling what response the animal should perform (its behavioral significance). In this task, the animal had to release the lever even on the trial where no juice was given in order to advance to the next trial. A total of 423 units showed activity changes in relation to one or more of the task events, such as the cue presentation, delay, release response and reward delivery. Among 313 units which showed cue-related activity changes, 179 units showed differential activity in relation to the different cues. A majority of them (Type M; n = 120) showed activity changes in relation to whether the cue indicated juice delivery or not, independent of its physical properties. The activity of 13 units (Type P) was related to the physical properties of the stimulus, and the activity of the remaining 46 units (Type MP) appeared to be related to both aspects of the stimulus. Sustained activity changes during the delay period were observed in 68 Type M, in 3 Type P and in 24 Type MP units. The results suggest that the prefrontal cortex plays important roles in the stimulus-reward association and that prefrontal units are involved in higher order information processing, extracting and retaining the "associative significance" of the stimulus independent of its physical properties.

Time‐Cost Trade‐Off Among Related Activities

This paper describes the typical pragmatic approach that construction planners take in performing time-cost trade-off (TCT). In general, projects have major dominant characteristics, operations, or resources whose planning affects or dominates planning of other operations and resources. Planning focuses first on the dominant characteristics and is then fine-tuned in its details. Planners typically cycle between plan generation and cost estimating at ever finer levels of detail until they settle on a plan that has an acceptable cost and duration. Computerized TCT methods do not follow this cycle. Instead, they separate the plan into activities, each of which is assumed to have a single time-cost curve in which all points are compatible and independent of all points in other activities’ curves and that contains all direct cost differences among its methods. In general, these assumptions are not true for construction. Construction activities are related because they share methods and resources. Crashing activities usually require changes from normal, least-cost methods and resources. Changes in one activity are not independent of changes in related activities. Therefore, normal computerized TCT techniques are conceptually wrong for construction and they are not useful in practice.

The feeding, growth and behaviour of juvenile cod, Gadus morhua L., in cold environments

Most studies on feeding‐related activities of fish in cold water (0° C) have not used eurythermal species or examined a broad suite of activities. In this study we report on the feeding, growth, behaviour and conversion‐efficiency of 0 + Atlantic cod in response to water temperature and food availability. In one experiment, activity, opercular beat and growth decreased with decreasing temperature over the range 8·3–0·6° C. However, the conversion efficiency increased with decreasing temperature, a result partly explained by the relative change in activity and opercular rate. In another experiment, temperature had a linear effect on growth in cod fed different food rations. Both food availability and temperature were found to influence growth in group 0 + cod. The specific growth rate of cod in this experiment exceeded 2% day‐1. Growth data collected from cod sampled in the field during the cold‐water period showed a progressive increase of mean length over the season. Overall, these results demonstrate that 0 + cod have adapted to life in cold‐water environments, in contrast to adult cod which mostly inhabit warmer environments.

Proline Metabolism in Solanum tuberosum Cell Suspension Cultures Under Water Stress

Summary Application of water stress (10% w/v polyethylene glycol 6000, PEG) to potato cell suspension cultures resulted in an increase of the proline pool from 2.3 to 20.7 μmol/g dry mass. Despite this proline accumulation in stressed potato cells, no in vitro changes in relative activities of key enzymes of basic metabolic pathways thought to be involved in proline biosynthesis could be detected. The pyridine nucleotide reduction charges, which are measures of the nucleotide signaling system of a cell, were also the same in stressed and non-stressed cells. The results are discussed in terms of water-stress-induced changes of the physico-chemical state of the aqueous cytoplasm. These changes of the microenvironment of the aqueous cytoplasm probably alter the efficiency of the multi-enzyme reaction chains involved in proline biosynthesis.

Differences in CO2 threshold of respiratory muscles in preterm infants.

Because neonatal apnea is frequently associated with airway obstruction, we compared relative changes in activity between various upper airway muscles and the diaphragm during hypercapnic stimulation. The technique of hyperoxic CO2 rebreathing was employed in 17 healthy, sleeping preterm infants studied at a postnatal age of 32 +/- 12 days. Surface diaphragm (DIA) electromyograms (EMGs) were recorded in all infants, and noninvasive measurements of posterior cricoarytenoid (PCA), genioglossus (GG), and alae nasi (AN) EMGs were analyzed in 11, 9, and 8 infants, respectively. During the control period, consistent phasic EMGs were recorded from the DIA in all infants and from the PCA in 8 infants, but from the GG and AN each in only one infant. During CO2 rebreathing, minute ventilation and end-tidal CO2 increased linearly as CO2 rose from 31 +/- 5 to 51 +/- 5 Torr. DIA and PCA EMGs also had proportional and comparable increases throughout rebreathing. In contrast, both GG and AN responses differed from the DIA and PCA (P less than 0.001) and exhibited minimal or absent responses at low levels of hypercapnia. Consistent GG and AN EMGs appeared at comparable levels of end-tidal CO2 (47 +/- 5 and 45 +/- 5 Torr, respectively) and subsequently increased linearly in most infants. We conclude that during CO2 rebreathing the initially delayed and subsequently linear responses of the GG and AN EMGs indicate a high CO2 threshold for these muscles.

Neuronal activity in cortical motor areas related to ipsilateral, contralateral, and bilateral digit movements of the monkey.

1. Single cell activity was studied in the precentral (PCM), premotor (PM), and supplementary (SMA) motor cortex of the monkey to compare magnitudes of activity changes in relation to ipsilateral, contralateral, and bilateral digit movements. 2. Three Japanese monkeys were trained to press a small key with the right or left hand, or with both hands, in accordance with visual instruction signals given 2.6-5.4 s before a visual movement-trigger signal. Great care was taken to train the animal to use only the required part of the limb. As a result of extensive training, electromyographic (EMG) studies revealed that muscle activities before the key press were limited to the digit and hand muscles of the limb instructed to move. No overt increase or decrease in activity was detectable in the proximal limb or body muscles in relation to the key-press movements or instructions. 3. Even though the movement was thus limited to distal forelimb, distinct ipsilateral relationships were observed in 8.2% of the task-related PCM neurons. They changed their activity before ipsilateral and bilateral (but not before contralateral) key press. 4. A majority of the neurons recorded from the digit area of PCM (mostly limited to the anterior bank of the central sulcus) exhibited a contralateral relationship; namely the activity increased or decreased before the onset of the contralateral and bilateral key-press movements. In most of them, the magnitudes of the activity changes before the contralateral and bilateral movements were similar. 5. In proximal limb and trunk areas of PCM and also in the somatosensory cortex, no neurons were found to exhibit distinct relations to any of the key-press movements. 6. In both SMA and PM, a number of neurons exhibited relationships of the type never or only rarely observed in the primary motor cortex. Thirty-seven percent of SMA and 62% of PM neurons exhibited premovement activity changes before all of the key-press movements. The movement-specific type of activity was observed in 28% of SMA and 16% of PM neurons. In these neurons, the activity changes were observed in relation to only one of the right or left key-press movements or exclusively in relation to the bilateral key press. Neuronal activity resembling the majority of the PCM neurons (contralateral type) was observed in 31% of SMA and 13% of PM neurons. 7. Instruction-induced changes in activity were more often found in the secondary than in the primary motor area.(ABSTRACT TRUNCATED AT 400 WORDS)

Neuronal activity in the postcentral cortex related to force regulation during a precision grip task

Recordings from single neurons in the primary somatosensory cortex of the monkey during force regulation between the fingers showed following characteristics: (1) the existence of classes of discharge patterns similar to those in motor cortex, but with differences in their distribution, (2) a late onset of activity changes in relation to force increase and (3) a linear relation to force, but with shallow mean rate-force slope.

Acid Phosphatase Activity in Karri (Eucalyptus diversicolorF. Muell.) in Relation to Soil Phosphate and Nitrogen Supply

O'Connell, A. M. and Grove, T. S. 1985. Acid phosphatase activity in karri (Eucalyptus diversicolor F. Muell.) in relation to soil phosphate and nitrogen supply.—J. exp. Bot. 36: 1359-1372. Soluble acid phosphatase activity was measured in tissues of karri (Eucalyptus diversicolor F. Muell.) seedlings and five year old karri trees to which P and N fertilizer had been applied. Addition of P from 0 to 1250 mg P kg1 soil with a basal treatment of other nutrients produced significant increases in growth, P content and P concentration of karri seedlings. In each of five plant components (shoot tips, partly expanded leaves, mature leaves, young stems and old stems) soluble acid phosphatase activity was greatest at low levels of added P and decreased with increasing soil P supply. The range of acid phosphatase activity (0-5-6-5 pmol NPP g 1 f.wt. min ') was similar to that reported for a number of agricultural and horticultural plants. Enzyme activity was highest for shoot tips and lowest for old stems. Flowever, the relative change in activity with decreasing soil P supply was greatest for stems (4-3 fold) and least for shoot tips (2-7 fold). Mature leaves of seedlings grown in 'high P' and 'low P' soil at four levels of added N showed, in addition to the effect of P, a significant N-P interaction on soluble acid phosphatase activity. In leaf samples from five year old karri trees there was a significant decrease in soluble acid phosphatase with increasing P fertilization. Addition of N fertilizer had no significant effect on enzyme activity, probably because added N had little effect on foliar N concentrations. Exponential models relating (1) plant growth to enzyme activity and (2) plant growth to P concentration in stems and mature leaves of plants grown in soil with a range of added P accounted for 78-92% and 63-87%, respectively, of the variation in top dry weight. The results suggest that for the diagnosis of plant P status, (1) stem components may be the most appropriate tissue to sample, and (2) nutrient and enzyme assays may complement each other, P concentration being most useful where P supply is adequate and phosphatase activity where P supply limits growth.

Microsomal Aryl Hydrocarbon Hydroxylase Comparison of the Direct, Indirect and Radiometric Assays

Abstract The direct fluorometric assay of aryl hydrocarbon hydroxylase has been compared to the more commonly used indirect fluorometric and radiometric assays. Although rat hepatic microsomal activities measured by the direct assay were consistently higher than those obtained by the other assays, the relative changes in activity following enzyme induction and/or inhibition were similar. The direct assay provides an accurate and rapid measure of aryl hydrocarbon hydroxylase activity and avoids several problems inherent in the indirect and radiometric assays.

Energy metabolism and ageing of Phormia terraenovae—I. Programmed changes of enzyme activities and substrate concentrations in carbohydrate metabolism

1. 1. The age related activity changes of glycolytic key enzymes (PFK, aldolase, GADPH an PK; and their corresponding substrates were determined in thoraxes of male blowflies Phormia terraenovae. 2. 2. All enzyme activities rise rapidly during the first days after emergence reaching a maximum near the 12th day, thereafter they decrease to a nearly constant level between the 17th and 23rd day of adult life. 3. 3. The glycolytic capacity is reduced after the second week but no defect in the glycolytic flow appears as the constant quotient between aldolase and GAPDH and the unchanged energy charge shows. 4. 4. Flight performance is not affected by enzyme activity or substrate concentration changes.

Changes in cyclic AMP-dependent protein kinases during inhibition of mastocytoma cell growth by dibutyryl cyclic AMP.

Inhibition of growth of PY815 mouse mastocytoma cells in vitro by N6,O2'-dibutyryladenosine 3',5' cyclic monophosphate (DB cyclic AMP) was accompanied by increases in intracellular cyclic AMP and histamine and minor changes in cytosolic cyclic AMP-dependent histone kinase activity. However, DEAE-cellulose chromatography revealed substantial changes in the relative proportions of the principal cyclic AMP-dependent protein kinases and in free cyclic AMP-binding protein after DB cyclic AMP treatment. The activity of cytosolic cyclic AMP-dependent protein kinase type I (PKI) decreased relative to cyclic AMP-dependent protein kinase type II (PKII) and there was an increase in a cytosol cyclic AMP-binding protein with little associated protein kinase activity. The relative changes in activity of PKI, PKII and cyclic AMP binding protein after DB cyclic AMP treatment may reflect events important in the regulation of growth and differentiation of mast cells.