Glycolytic component of rat spermatid energy and acid-base metabolism

1990 ◽  
Vol 259 (4) ◽  
pp. C660-C667 ◽  
Author(s):  
J. G. Reyes ◽  
M. V. Velarde ◽  
R. Ugarte ◽  
D. J. Benos
Keyword(s):  
Lactate Production ◽  
Co2 Production ◽  
Simultaneous Occurrence ◽  
Atp Content ◽  
Extracellular Medium ◽  
Glucose Addition ◽  
Intracellular Atp ◽  
Acid Diffusion ◽  
Glucose Analogues ◽  
The Impact

The impact of glycolysis on rat spermatid energy metabolism is made apparent by the simultaneous occurrence of the following three events upon glucose addition to the extracellular medium of a rat spermatid cell suspension: decrease in ATP content, exit of acid equivalents, and increased lactate production and efflux. In this work, we have studied the interrelations between these three phenomena. By measuring ATP content, net acid transport, lactate exit, oxygen consumption, intracellular pH, CO2 production, and glycolytic intermediates in the presence of glucose and glucose analogues, we conclude that 1) lactate production, decrease in ATP content, and acid equivalent exit are dependent on the metabolism of glucose up to different stages in glycolysis. 2) The decrease in ATP content is not directly related to the exit of acid equivalents from rat spermatids. 3) Glucose metabolism is a net ATP-consuming process at high intracellular ATP content but is a net ATP-producing process at low intracellular ATP concentration in rat spermatids. 4) Acid equivalent production arises from the metabolism of glucose beyond glyceraldehyde 3-phosphate dehydrogenase. 5) Lactic acid diffusion and/or lactate transport and CO2 production and exit could account for the glucose-dependent acid equivalent efflux in rat spermatids.

Decreased insulin binding and degradation associated with depressed intracellular ATP content

Diabetes ◽  
1980 ◽  
Vol 29 (3) ◽  
pp. 221-226 ◽  
Author(s):  
B. Draznin ◽  
C. C. Solomons ◽  
C. A. Emler ◽  
D. S. Schalch ◽  
K. E. Sussman
Keyword(s):  
Insulin Binding ◽  
Atp Content ◽  
Intracellular Atp

Selenium promotes proliferation of chondrogenic cell ATDC5 by increment of intracellular ATP content under serum deprivation

2012 ◽  
Vol 30 (8) ◽  
pp. 657-663 ◽  
Author(s):  
Jidong Yan ◽  
Juan Tian ◽  
Yuewen Zheng ◽  
Yan Han ◽  
Shemin Lu
Keyword(s):  
Serum Deprivation ◽  
Atp Content ◽  
Intracellular Atp

scholarly journals Atmospheric fluidized bed gasification of promising biomass fuels in southern European regions

2007 ◽  
Vol 11 (1) ◽  
pp. 5-15 ◽  
Author(s):  
Kyriakos Panopoulos ◽  
Lydia Fryda ◽  
Emmanuel Kakaras
Keyword(s):  
Fluidized Bed ◽  
Lignin Content ◽  
Giant Reed ◽  
Co2 Production ◽  
European Regions ◽  
Biomass Fuels ◽  
Product Gas ◽  
Sorghum Bagasse ◽  
Bed Material ◽  
The Impact

Three promising biomass fuels from southern European regions were gasified atmospherically with air in a lab-scale fluidized bed reactor with quartz or olivine as bed material. The fuels used were an agro-industrial residue (olive bagasse) and the energy crops giant reed and sweet sorghum bagasse. Varying air ratios and temperatures were tested to study the impact on the product gas composition and tar load. Tars were higher in the case of olive bagasse, attributed to its higher lignin content compared to the other two biomasses with higher cellulose. Giant reed gasification causes agglomeration and defluidisation problems at 790?C while olive bagasse shows the least agglomeration tendency. The particular olivine material promoted the destruction of tars, but to a lesser level than other reported works; this was attributed to its limited iron content. It also promoted the H2 and CO2 production while CO content decreased. Methane yield was slightly affected (decreased) with olivine, higher temperatures, and air ratios. Air ratio increase decreased the tar load but at the same time the gas quality deteriorated. .

scholarly journals Mitochondrial genome and its regulator TFAM modulates head and neck tumourigenesis through intracellular metabolic reprogramming and activation of oncogenic effectors

2021 ◽  
Vol 12 (11) ◽  
Author(s):  
Yi-Ta Hsieh ◽  
Hsi-Feng Tu ◽  
Muh-Hwa Yang ◽  
Yi-Fen Chen ◽  
Xiang-Yun Lan ◽  
...  
Keyword(s):  
Head And Neck ◽  
Tongue Cancer ◽  
Aerobic Glycolysis ◽  
Lactate Production ◽  
Cellular Level ◽  
Metabolic Reprogramming ◽  
Transport Chain ◽  
Genetically Manipulated ◽  
The Impact

AbstractMitochondrial transcriptional factor A (TFAM) acts as a key regulatory to control mitochondrial DNA (mtDNA); the impact of TFAM and mtDNA in modulating carcinogenesis is controversial. Current study aims to define TFAM mediated regulations in head and neck cancer (HNC). Multifaceted analyses in HNC cells genetically manipulated for TFAM were performed. Clinical associations of TFAM and mtDNA encoded Electron Transport Chain (ETC) genes in regulating HNC tumourigenesis were also examined in HNC specimens. At cellular level, TFAM silencing led to an enhanced cell growth, motility and chemoresistance whereas enforced TFAM expression significantly reversed these phenotypic changes. These TFAM mediated cellular changes resulted from (1) metabolic reprogramming by directing metabolism towards aerobic glycolysis, based on the detection of less respiratory capacity in accompany with greater lactate production; and/or (2) enhanced ERK1/2-Akt-mTORC-S6 signalling activity in response to TFAM induced mtDNA perturbance. Clinical impacts of TFAM and mtDNA were further defined in carcinogen-induced mouse tongue cancer and clinical human HNC tissues; as the results showed that TFAM and mtDNA expression were significantly dropped in tumour compared with their normal counterparts and negatively correlated with disease progression. Collectively, our data uncovered a tumour-suppressing role of TFAM and mtDNA in determining HNC oncogenicity and potentially paved the way for development of TFAM/mtDNA based scheme for HNC diagnosis.

scholarly journals Anatomy of simultaneous flood peaks at a lowland confluence

2018 ◽  
Vol 22 (10) ◽  
pp. 5599-5613 ◽  
Author(s):  
Tjitske J. Geertsema ◽  
Adriaan J. Teuling ◽  
Remko Uijlenhoet ◽  
Paul J. J. F. Torfs ◽  
Antonius J. F. Hoitink
Keyword(s):  
Economic Value ◽  
Water Levels ◽  
Simultaneous Occurrence ◽  
Main Stream ◽  
Time Lags ◽  
Main River ◽  
Long Duration ◽  
Independent Observations ◽  
Flood Peaks ◽  
The Impact

Abstract. Lowlands are vulnerable to flooding due to their mild topography in often densely populated areas with high social and economic value. Moreover, multiple physical processes coincide in lowland areas, such as those involved in river–sea interactions and in merging rivers at confluences. Simultaneous occurrence of such processes can result in amplifying or attenuating effects on water levels. Our aim is to understand the mechanisms behind simultaneous occurrence of discharge waves in a river and its lowland tributaries. Here, we introduce a new way of analyzing lowland discharge and water level dynamics, by tracing individual flood waves based on dynamic time warping. We take the confluence of the Meuse River (∼33 000 km2) with the joining tributaries of the Dommel and Aa rivers as an example, especially because the January 1995 flood at this confluence was the result of the simultaneous occurrence of discharge peaks in the main stream and the tributaries and because independent observations of water levels and discharge are available for a longer period. The analysis shows that the exact timing of the arrival of discharge peaks is of little relevance because of the long duration of the average discharge wave compared to typical time lags between peaks. The discharge waves last on average 9 days, whereas the lag time between discharge peaks in the main river and the tributaries is typically 3 days. This results in backwaters that can rise up to 1.5 m over a distance of 4 km from the confluence. Thus, local measures to reduce the impact of flooding around the confluence should account for the long duration of flood peaks in the main system.

Modulation of Na+/H+exchange activity by Cl−

2001 ◽  
Vol 281 (1) ◽  
pp. C133-C141 ◽  
Author(s):  
Orit Aharonovitz ◽  
András Kapus ◽  
Katalin Szászi ◽  
Natasha Coady-Osberg ◽  
Tim Jancelewicz ◽  
...  
Keyword(s):  
Cell Volume ◽  
Underlying Mechanism ◽  
Intrinsic Activity ◽  
Atp Content ◽  
Extracellular Medium ◽  
Optimal Activity ◽  
Terminal Domain ◽  
Normal Transport ◽  
The Individual ◽  
Exchange Activity

Na+/H+ exchanger (NHE) activity is exquisitely dependent on the intra- and extracellular concentrations of Na+ and H+. In addition, Cl− ions have been suggested to modulate NHE activity, but little is known about the underlying mechanism, and the Cl− sensitivity of the individual isoforms has not been established. To explore their Cl− sensitivity, types 1, 2, and 3 Na+/H+ exchangers (NHE1, NHE2, and NHE3) were heterologously expressed in antiport-deficient cells. Bilateral replacement of Cl− with nitrate or thiocyanate inhibited the activity of all isoforms. Cl− depletion did not affect cell volume or the cellular ATP content, which could have indirectly altered NHE activity. The number of plasmalemmal exchangers was unaffected by Cl− removal, implying that inhibition was due to a decrease in the intrinsic activity of individual exchangers. Analysis of truncated mutants of NHE1 revealed that the anion sensitivity resides, at least in part, in the COOH-terminal domain of the exchanger. Moreover, readdition of Cl− into the extracellular medium failed to restore normal transport, suggesting that intracellular Cl− is critical for activity. Thus interaction of intracellular Cl− with the COOH terminus of NHE1 or with an associated protein is essential for optimal activity.

scholarly journals Long-term HIF-1α transcriptional activation is essential for heat-acclimation-mediated cross tolerance: mitochondrial target genes

2017 ◽  
Vol 312 (5) ◽  
pp. R753-R762 ◽  
Author(s):  
Rivka Alexander-Shani ◽  
Ahmad Mreisat ◽  
Elia Smeir ◽  
Gary Gerstenblith ◽  
Michael D. Stern ◽  
...  
Keyword(s):  
Transcriptional Activation ◽  
Target Genes ◽  
Ischemia Reperfusion ◽  
Mitochondrial Gene ◽  
Lactate Production ◽  
Heat Acclimation ◽  
Cross Tolerance ◽  
Metabolic Switch ◽  
Atp Production ◽  
The Impact

An important adaptive feature of heat acclimation (HA) is the induction of cross tolerance against novel stressors (HACT) Reprogramming of gene expression leading to enhanced innate cytoprotective features by attenuating damage and/or enhancing the response of “help” signals plays a pivotal role. Hypoxia-inducible factor-1α (HIF-1α), constitutively upregulated by HA (1 mo, 34°C), is a crucial transcription factor in this program, although its specific role is as yet unknown. By using a rat HA model, we studied the impact of disrupting HIF-1α transcriptional activation [HIF-1α:HIF-1β dimerization blockade by intraperitoneal acriflavine (4 mg/kg)] on its mitochondrial gene targets [phosphoinositide-dependent kinase-1 (PDK1), LON, and cyclooxygenase 4 (COX4) isoforms] in the HA rat heart. Physiological measures of cardiac HACT were infarct size after ischemia-reperfusion and time to rigor contracture during hypoxia in cardiomyocytes. We show that HACT requires transcriptional activation of HIF-1α throughout the course of HA and that this activation is accompanied by two metabolic switches: 1) profound upregulation of PDK1, which reduces pyruvate entry into the mitochondria, consequently increasing glycolytic lactate production; 2) remodeling of the COX4 isoform ratio, inducing hypoxic-tolerant COX4.2 dominance, and optimizing electron transfer and possibly ATP production during the ischemic and hypoxic insults. LON and COX4.2 transcript upregulation accompanied this shift. Loss of HACT despite elevated expression of the cytoprotective protein heat shock protein-72 concomitantly with disrupted HIF-1α dimerization suggests that HIF-1α is essential for HACT. The role of a PDK1 metabolic switch is well known in hypoxia acclimation but not in the HA model and its ischemic setting. Remodeling of COX4 isoforms by environmental acclimation is a novel finding.

scholarly journals The influence of insulin and of contraction on glucose metabolism in the perfused diaphragm muscle from normal and streptozotocin-treated rats

1971 ◽  
Vol 125 (1) ◽  
pp. 97-103 ◽  
Author(s):  
Anne Beloff-Chain ◽  
E. B. Chain ◽  
K. A. Rookledge
Keyword(s):  
Glucose Metabolism ◽  
Glycogen Synthesis ◽  
Lactate Production ◽  
Diaphragm Muscle ◽  
Co2 Production ◽  
Experimental Conditions ◽  
Contracting Muscle ◽  
Hexose Phosphate ◽  
Muscle Formation ◽  
Resting Muscle

1. The metabolism of [U-14C]glucose in perfused resting and contracting diaphragm muscle from normal rats and rats made diabetic with streptozotocin was studied in the presence and absence of insulin. 2. The incorporation of [U-14C]-glucose into glycogen and oligosaccharides was stimulated by insulin under all experimental conditions studied. 3. In the normal perfused resting diaphragm muscle the incorporation of radioactivity from [14C]glucose into lactate and CO2 was not affected by insulin. 4. Periodic contractions, induced by electrical stimulation of the perfused diaphragm muscle in the absence of insulin, caused an increased incorporation of 14C into glycogen and hexose phosphate esters, whereas incorporation of 14C into lactate was greatly decreased. Production of 14CO2 in the contracting muscle was not significantly different from that in resting muscle. Addition of insulin to the perfusion liquid caused a further increase in formation of [14C]-glycogen in contracting muscle to values reached in the resting muscle in the presence of insulin. Formation of [14C]lactate was also stimulated by insulin, to values close to those found in the resting muscle in the presence of insulin. 5. In the diabetic resting muscle the rate of glucose metabolism was very low in the absence of insulin. Insulin increased formation of [14C]glycogen to the value found in normal muscle in the absence of insulin. Production of 14CO2 and formation of [14C]hexose phosphate remained unchanged. 6. In the diabetic contracting muscle production of 14CO2 was increased to values approaching those found in normal contracting muscle. Formation of [14C]lactate and [14C]glycogen was also increased by contraction, to normal values. Only traces of [14C]hexose phosphate were detectable. Addition of insulin to the perfusion medium stimulated formation of [14C]glycogen, to values found in normal contracting muscle. Production of [14C]hexose phosphate was stimulated by insulin, to approximately the values found in the normal contracting muscle. Production of 14CO2 and [14C]lactate, however, was not significantly affected by insulin. 7. These results indicate that the defects of glucose metabolism observed in perfused resting diabetic diaphragm muscle can be partially corrected by contraction, and in the presence of insulin the contracting diabetic muscle has a completely normal pattern of glycogen synthesis and lactate production, but CO2 production remains impaired.

Extension of 3DVAR to 4DVAR: Implementation of 4DVAR at the Meteorological Service of Canada

2007 ◽  
Vol 135 (6) ◽  
pp. 2339-2354 ◽  
Author(s):  
Pierre Gauthier ◽  
Monique Tanguay ◽  
Stéphane Laroche ◽  
Simon Pellerin ◽  
Josée Morneau
Keyword(s):  
Data Assimilation ◽  
Global Analysis ◽  
Variational Data Assimilation ◽  
Simultaneous Occurrence ◽  
Strong Wind ◽  
Surface Drag ◽  
Vertical Diffusion ◽  
Regional Forecasts ◽  
The Impact ◽  
Lagrangian Scheme

Abstract On 15 March 2005, the Meteorological Service of Canada (MSC) proceeded to the implementation of a four-dimensional variational data assimilation (4DVAR) system, which led to significant improvements in the quality of global forecasts. This paper describes the different elements of MSC’s 4DVAR assimilation system, discusses some issues encountered during the development, and reports on the overall results from the 4DVAR implementation tests. The 4DVAR system adopted an incremental approach with two outer iterations. The simplified model used in the minimization has a horizontal resolution of 170 km and its simplified physics includes vertical diffusion, surface drag, orographic blocking, stratiform condensation, and convection. One important element of the design is its modularity, which has permitted continued progress on the three-dimensional variational data assimilation (3DVAR) component (e.g., addition of new observation types) and the model (e.g., computational and numerical changes). This paper discusses some numerical problems that occur in the vicinity of the Poles where the semi-Lagrangian scheme becomes unstable when there is a simultaneous occurrence of converging meridians and strong wind gradients. These could be removed by filtering the winds in the zonal direction before they are used to estimate the upstream position in the semi-Lagrangian scheme. The results show improvements in all aspects of the forecasts over all regions. The impact is particularly significant in the Southern Hemisphere where 4DVAR is able to extract more information from satellite data. In the Northern Hemisphere, 4DVAR accepts more asynoptic data, in particular coming from profilers and aircrafts. The impact noted is also positive and the short-term forecasts are particularly improved over the west coast of North America. Finally, the dynamical consistency of the 4DVAR global analyses leads to a significant impact on regional forecasts. Experimentation has shown that regional forecasts initiated directly from a 4DVAR global analysis are improved with respect to the regional forecasts resulting from the regional 3DVAR analysis.

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