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Basal Rate (basal + rate)

Distribution by Scientific Domains

Life Sciences	54%
Medical Sciences	45%

Selected Abstracts

Mitochondrial function and apoptotic susceptibility in aging skeletal muscle

AGING CELL, Issue 1 2008
Béatrice Chabi
Summary During aging, skeletal muscle undergoes sarcopenia, a condition characterized by a loss of muscle cell mass and alterations in contractile function. The origin of these decrements is unknown, but evidence suggests that they can be partly attributed to mitochondrial dysfunction. To characterize the nature of this dysfunction, we investigated skeletal muscle contractile properties, subsarcolemmal (SS) and intermyofibrillar (IMF) mitochondrial biogenesis and function, as well as apoptotic susceptibility in young (6 months old) and senescent (36 months old) Fischer 344 Brown Norway rats. Muscle mass and maximal force production were significantly lower in the 36-month group, which is indicative of a sarcopenic phenotype. Furthermore, contractile activity in situ revealed greater fatigability in the 36-month compared to the 6-month animals. This decrement could be partially accounted for by a 30% lower mitochondrial content in fast-twitch muscle from 36-month animals, as well as lower protein levels of the transcriptional coactivator peroxisome proliferator-activated receptor , coactivator-1,. Enzyme activities and glutamate-induced oxygen consumption rates in isolated SS and IMF mitochondria were similar between age groups. However, mitochondrial reactive oxygen species (ROS) production during state 3 respiration was ~1.7-fold greater in mitochondria isolated from 36-month compared to 6-month animals, and was accompanied by a 1.8-fold increase in the DNA repair enzyme 8-oxoguanine glycosylase 1 in fast-twitch muscle. Basal rates of release of cytochrome c and endonuclease G in SS mitochondria were 3.5- to 7-fold higher from senescent animals. These data suggest that the age-related sarcopenia and muscle fatigability are associated with enhanced ROS production, increased mitochondrial apoptotic susceptibility and reduced transcriptional drive for mitochondrial biogenesis. [source]

Minimizing energy expenditure facilitates vertebrate persistence on oceanic islands

ECOLOGY LETTERS, Issue 5 2002
Brian K. McNab
Abstract The characteristics of terrestrial vertebrates on oceanic islands are examined. They often include a reduced body size, a tolerance of conspecifics, flightlessness, a reduced basal rate of metabolism, and a propensity to enter torpor. On oceanic islands ectotherms frequently replace endotherms. These changes reduce the energy expenditure and resource requirements of vertebrates. Such reductions are permitted by the absence of mammalian predators and facilitate the survival of island endemics in the face of a restricted resource base and a variable environment through an increase in population size. Some insular species increase body size, but this occurs only when the resource base is large, due either to a fortuitously abundant resource, or to the absence of other species that exploit normally abundant resources. Some questions are posed to guide future work. They examine of the characteristics that permit species to disperse over water barriers, the conditions that require a reduction in resource use, the rapidity of response by immigrants to island conditions, whether supertramps show physiological differentiation with respect to island distance or size, and whether island size is absolute or relative to the size of the immigrants. [source]

Functional analysis of CBP/p300 in embryonic orofacial mesenchymal cells

JOURNAL OF CELLULAR BIOCHEMISTRY, Issue 5 2006
D.R. Warner
Abstract CREB binding protein (CBP) and the close structural homolog, p300, are nuclear coactivators of multiple signaling pathways that play important roles in embryonic development and cellular homeostasis. TGF, regulates the proliferation rate of many cell types and has been demonstrated to inhibit the growth rate of mouse embryonic maxillary mesenchymal (MEMM) cells. The role of CBP and p300 in TGF,-mediated control of proliferation of MEMM cells was thus investigated using an in vitro gene knockdown approach. TGF, reporter assays demonstrated that p300 mRNA knockdown via targeted siRNAs led to a reduction in the response to TGF,, whereas knockdown of CBP by the same approach had an insignificant effect. In MEMM cell proliferation assays, siRNA-mediated knockdown of CBP and/or p300 had little impact upon TGF,-mediated growth inhibition; however, the basal rate of proliferation was increased. Inhibition of p300 activity via overexpression of a dominant-negative mutant (p300,C/H3) led to significant inhibition of TGF,-mediated activation of p3TP-lux. As with the siRNA knockdown approach, p300,C/H3 also increased the basal rate of cell proliferation of MEMM cells. CBP/p300 siRNA knockdown had a significant but incomplete inhibition of TGF,-induction of matrix metalloproteinase-9 (gelatinase B) expression. These data demonstrate that p300 is involved in Smad-mediated transcription of p3TP-lux, however, its role (and that of CBP) in biological processes such as the control of cell proliferation and extracellular matrix metabolism is more complex and may be mediated via mechanisms beyond coactivator recruitment. J. Cell. Biochem. 99: 1374,1379, 2006. © 2006 Wiley-Liss, Inc. [source]

Regulation of Eukaryotic Initiation Factor 4E Phosphorylation in the Nervous System of Aplysia californica

JOURNAL OF NEUROCHEMISTRY, Issue 2 2000
John R Dyer
We have used an antibody that specifically recognizes eukaryotic initiation factor 4E (eIF4E) when it is phosphorylated at Ser207 to characterize eIF4E phosphorylation in the nervous system of Aplysia. The level of phosphorylated eIF4E, but not the level of total eIF4E, was significantly correlated with the basal rate of translation measured from different animals. Serotonin (5-HT), a transmitter that regulates the rate of translation in Aplysia neurons, had mixed effects on eIF4E phosphorylation. 5-HT decreased eIF4E phosphorylation in sensory cell clusters through activation of protein kinase C. 5-HT increased eIF4E phosphorylation in the whole pleural ganglia. In the Aplysia nervous system, eIF4E phosphorylation correlated with phosphorylation of the p38 MAP kinase, but not the p42 MAP kinase (ERK). Furthermore, an inhibitor of the p38 MAP kinase significantly decreased basal eIF4E phosphorylation, but an inhibitor of the MAP or ERK kinase (MEK) did not. Despite the correlation of eIF4E phosphorylation with the basal rate of translation, inhibition of eIF4E phosphorylation by an inhibitor of the p38 MAP kinase did not significantly decrease the rate of translation. [source]

Disparity Between Tonic and Phasic Ethanol-Induced Dopamine Increases in the Nucleus Accumbens of Rats

ALCOHOLISM, Issue 7 2009
Donita L. Robinson
Background:, Dopamine concentrations in the nucleus accumbens fluctuate on phasic (subsecond) and tonic (over minutes) timescales in awake rats. Acute ethanol increases tonic concentrations of dopamine, but its effect on subsecond dopamine transients has not been fully explored. Methods:, We measured tonic and phasic dopamine fluctuations in the nucleus accumbens of rats in response to ethanol (within-subject cumulative dosing, 0.125 to 2 g/kg, i.v.). Results:, Microdialysis samples yielded significant tonic increases in dopamine concentrations at 1 to 2 g/kg ethanol in each rat, while repeated saline infusions had no effect. When monitored with fast scan cyclic voltammetry, ethanol increased the frequency of dopamine transients in 6 of 16 recording sites, in contrast to the uniform effect of ethanol as measured with microdialysis. In the remaining 10 recording sites that were unresponsive to ethanol, dopamine transients either decreased in frequency or were unaffected by cumulative ethanol infusions, patterns also observed during repeated saline infusions. The responsiveness of particular recording sites to ethanol was not correlated with either core versus shell placement of the electrodes or the basal rate of dopamine transients. Importantly, the phasic response pattern to a single dose of ethanol at a particular site was qualitatively reproduced when a second dose of ethanol was administered, suggesting that the variable between-site effects reflected specific pharmacology at that recording site. Conclusions:, These data demonstrate that the relatively uniform dopamine concentrations obtained with microdialysis can mask a dramatic heterogeneity of phasic dopamine release within the accumbens. [source]

Life with continuous subcutaneous insulin infusion (CSII) therapy: child and parental perspectives and predictors of metabolic control

PEDIATRIC DIABETES, Issue 2 2001
Aristides k Maniatis
Abstract: Objective:, The purpose of this study was twofold (i): to evaluate metabolic control in patients receiving CSII therapy in a routine pediatric diabetes clinic by describing reasons for initiating therapy and daily management issues, including needle fear; and (ii) to assess the change in parental involvement and anxiety once their child initiated CSII therapy. Research design and methods: The study included 52 subjects (aged 7.6,23.6 yr) from a general pediatric diabetes clinic. Management issues were defined as diet, exercise, home blood glucose monitoring (HBGM) frequency, and self/staff assessment of needle fear. Characteristics were analyzed both according to a 0.5% change in HbA1c status (decreased vs. stable vs. increased) compared with pre-CSII therapy, and final HbA1c achieved (, 8.1 vs. > 8.1%). Results: The primary recommendation source for CSII use was most often the physician/diabetes team (48.1%), followed by a combination of the former with a personal referral source (32.7%). The most common reason (71.2%) for CSII initiation was a combination of wanting to achieve better metabolic control, dislike of insulin injections, and/or increased flexibility in daily living. Over one-quarter (26.9%) of subjects were identified as being needle-fearful, and this characteristic was predictive of final metabolic control (3/25 subjects ,,8.1% vs. 11/27 subjects >,8.1%, p =,0.03). On CSII therapy, dietary carbohydrate consistency was highly variable, and most subjects (65.3%) exclusively used an insulin to carbohydrate ratio for insulin bolus dosage calculation. The most common adjustment strategy (63.5%) for exercise was a combination of decreasing the insulin basal rate, disconnecting the pump, and/or eating extra carbohydrates. For the total cohort, the frequency of HBGM significantly increased on CSII therapy (4.31,4.85 tests/day, p =,0.02). Females did not have a significant change in HBGM frequency, while the youngest subjects had the highest HBGM frequency. Parental involvement and anxiety primarily stayed the same or decreased, regardless of the child's age (, 18 vs. > 18 yr) or metabolic control. Conclusions:, Analyses of the various characteristics identified only needle fearfulness as being predictive of poor metabolic control. Interestingly, poor control with CSII therapy did not result in a significant increase in parental involvement and/or anxiety. [source]

Effect of intermittent and continuous exposure to electromagnetic fields on cultured hippocampal cells

BIOELECTROMAGNETICS, Issue 2 2002
A. Boland
Abstract This study was designed to assess the effect of 50 Hz electromagnetic fields (EMFs) on hippocampal cell cultures in the presence or absence of either sodium nitroprusside (SNP, a NO donor) or Fe2+ induced oxidative stress. One week old cultured rat hippocampal cells were exposed to either intermittent EMFs (IEMFs, 50 Hz, 0,5 mT, 1 min ON/OFF cycles, repeated 10 times every 2 h, 6 times/day during 48 h) or continuous EMFs (CEMFs, 50 Hz, 0,5 mT for 48 h). In a second set of experiments, the effect on such EMFs applied in combination with oxidative stress induced by 0.5 ,M Fe2+ or SNP was estimated. At the end of both sets of experiments, cell mortality was assessed by lactate dehydrogenase measurements (LDH). Neither type of exposure to EMFs was observed to modify the basal rate of cell mortality. The exposure to CEMFs in presence of either NO or Fe2+ did not induce any significant increase in cell death. However, when cells were exposed to EMFs in the presence of NO, we observed a significant increase in cell death of 11 and 23% (P<0.001) at 2.5 and 5 mT, respectively. This effect had some specificity because IEMFs did not modify the effect of Fe2+ on cell mortality. Although the effects of IEMFs reported in this study were only observed at very high intensities, our model may prove valuable in trying to identify one cellular target of EMFs. Bioelectromagnetics 23:97,105, 2002. © 2002 Wiley-Liss, Inc. [source]

Age-dependent basal insulin patterns in children with type 1 diabetes treated with continuous subcutaneous insulin infusion

ACTA PAEDIATRICA, Issue 3 2009
Agnieszka Szypowska
Aims: Identifying age-dependent basal rates in type 1 diabetic children treated with continuous subcutaneous insulin infusion (CSII). Methods: CSII-treated children with type 1 diabetes exhibiting insulin requirement > 0.5U/kg and glycated haemoglobin (HbA1c) < 8%. The study population was composed of 198 Caucasian children (111 girls) with mean age of 9.8 ± 3.8 years, mean duration of diabetes of 4.3 ± 3.1 years and mean HbA1c value of 6.7 ± 0.7%. Data were evaluated for four age groups (0,6; 6,9; 9,12, 12,18 years). Basal rates records were downloaded from pump memory. HbA1c, weight, height were measured at scheduled visits. Results: Significant differences in the average hourly basal rate between groups were observed: I gr. 0.14 versus II gr. 0.24 versus III gr. 0.39 versus IV gr. 0.72 units/h; p < 0.0001. The average hourly basal rate correlated with age, body weight, BMI, diabetes duration and total insulin daily dose. Insulin peaks were observed for: I gr. , before midnight, II gr. , before midnight and in the early morning, gr. III and IV , in the early morning. Conclusion: Basal insulin infusion rate profiles in well-controlled paediatric patients on CSII reflect the age-dependent amount of basal insulin (20,40%) and affect circadian distribution of insulin needs. [source]

Diabetes management in the new millennium using insulin pump therapy

DIABETES/METABOLISM: RESEARCH AND REVIEWS, Issue S1 2002
Bruce W. Bode
Abstract Current goals of therapy of type 1 and 2 diabetes are to achieve near normal glycemia, minimize the risk of severe hypoglycemia, limit excessive weight gain, improve quality of life and delay or prevent late vascular complications. As discussed in this review, insulin pump or continuous subcutaneous insulin infusion (CSII) therapy provides a treatment option that can dramatically aid in achieving all of these goals. In comparison to multiple daily injections (MDI), CSII uses only rapid-acting insulin, provides greater flexibility in timing of meals and snacks, has programmable basal rates to optimize overnight glycemic control, can reduce the risk of exercise-induced hypoglycemia, and enhances patients' ability to control their own diabetes. Most important, in adults and adolescents with type 1 diabetes, CSII has been shown to lower HbA1c levels, reduce the frequency of severe hypoglycemia and limit excessive weight gain versus MDI without increasing the risk of diabetic ketoacidosis. Similarly positive results are being seen with CSII in adults with type 2 diabetes. The effectiveness of CSII and improvements in pump technology have fueled a dramatic increase in the use of this therapy. Practical guidelines are presented for selection of patients, initiation of treatment, patient education, follow-up assessments and troubleshooting. The recent introduction of methods for continuous glucose monitoring provides a new means to optimize the basal and bolus capabilities of CSII and offers the hope of the development of a feedback-controlled artificial pancreas. Copyright © 2002 John Wiley & Sons, Ltd. [source]

Temperature responses are a window to the physiology of dark respiration: differences between CO2 release and O2 reduction shed light on energy conservation

PLANT CELL & ENVIRONMENT, Issue 7 2008
JÖRG KRUSE
ABSTRACT We showed that temperature responses of dark respiration for foliage of Pinus radiata could be approximated by Arrhenius kinetics, whereby E0 determines shape of the exponential response and denotes overall activation energy of respiratory metabolism. Reproducible and predictable deviation from strict Arrhenius kinetics depended on foliage age, and differed between RCO2 and RO2. Inhibition of oxygen reduction (RO2) by cyanide (inhibiting COX) or SHAM (inhibiting AOX) resulted in reproducible changes of the temperature sensitivity for RO2, but did not affect RCO2. Enthalpic growth , preservation of electrons in anabolic products , could be approximated with knowledge of four variables: activation energies (E0) for both RCO2 and RO2, and basal rates of respiration at a low reference temperature (RREF). Rates of enthalpic growth by P. radiata needles were large in spring due to differences between RREF of oxidative decarboxylation and that of oxygen reduction, while overall activation energies for the two processes were similar. Later during needle development, enthalpic growth was dependent on differences between E0 for RCO2 as compared with RO2, and increased E0(RO2) indicated greater contributions of cytochrome oxidase to accompany the switch from carbohydrate sink to source. Temperature-dependent increments in stored energy can be calculated as the difference between RCO2,HCO2 and RO2,HO2. [source]