Visualizing metabolic transitions in aquatic mammals: does apnea plus swimming equal "diving"?

1988 ◽  
Vol 66 (1) ◽  
pp. 40-44 ◽  
Author(s):  
Michael A. Castellini
Keyword(s):  
Marked Change ◽  
Plasma Metabolites ◽  
Diving Response ◽  
Oxygen Utilization ◽  
Metabolic Plasticity ◽  
Long Duration ◽  
Metabolic Conditions ◽  
Metabolic Variation ◽  
The One ◽  
Aquatic Mammals

While diving, aquatic mammals must balance the oxygen conservation requirements of apnea with the oxygen utilization requirements of exercise. The resulting metabolic state depends on a complex range of behavioral, physiological, and metabolic conditions as required by the particular dive profile. Thus, at the one extreme of long duration diving, oxygen conservation requirements will outweigh those of exercise, while under conditions of rapid, short diving or propoising, exercise parameters will probably be of more importance than those of oxygen conservation. In the last several years, techniques for monitoring radioactively tagged plasma metabolites have allowed the visualization of metabolic variation throughout various diving and surface exercise regimes in aquatic mammals. By comparing such tracer turnover dilution curves under conditions of surface exercise, quiet forced diving, free diving, and sleep apnea, patterns emerge that demonstrate the extreme metabolic plasticity of the diving response. These comparisons have led to the conclusions that even short diving periods probably involve a marked change in metabolic steady state, and that aerobic diving is not simply analogous to aerobic exercise.

scholarly journals Apoptosis inducing factor and mitochondrial NADH dehydrogenases: redox-controlled gear boxes to switch between mitochondrial biogenesis and cell death

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Johannes M. Herrmann ◽  
Jan Riemer
Keyword(s):  
Cell Death ◽  
Complex I ◽  
Electron Transfer Reaction ◽  
Apoptotic Protein ◽  
Transport Chain ◽  
Metabolic Conditions ◽  
Nadh Dehydrogenases ◽  
The One ◽  
Apoptosis Inducing Factor ◽  
Redox Switches

AbstractThe mitochondrial complex I serves as entry point for NADH into the electron transport chain. In animals, fungi and plants, additional NADH dehydrogenases carry out the same electron transfer reaction, however they do not pump protons. The apoptosis inducing factor (AIF, AIFM1 in humans) is a famous member of this group as it was the first pro-apoptotic protein identified that can induce caspase-independent cell death. Recent studies on AIFM1 and the NADH dehydrogenase Nde1 of baker’s yeast revealed two independent and experimentally separable activities of this class of enzymes: On the one hand, these proteins promote the functionality of mitochondrial respiration in different ways: They channel electrons into the respiratory chain and, at least in animals, promote the import of Mia40 (named MIA40 or CHCHD4 in humans) and the assembly of complex I. On the other hand, they can give rise to pro-apoptotic fragments that are released from the mitochondria to trigger cell death. Here we propose that AIFM1 and Nde1 serve as conserved redox switches which measure metabolic conditions on the mitochondrial surface and translate it into a binary life/death decision. This function is conserved among eukaryotic cells and apparently used to purge metabolically compromised cells from populations.

An appropriate biomechanical model of seated human subjects exposed to whole-body vibration

2021 ◽  
pp. 146441932110394
Author(s):  
Raj Desai ◽  
Anirban Guha ◽  
Pasumarthy Seshu
Keyword(s):  
Degrees Of Freedom ◽  
Human Subjects ◽  
Computational Cost ◽  
Biomechanical Model ◽  
Whole Body ◽  
Body Parts ◽  
Lumped Parameter ◽  
Long Duration ◽  
The One ◽  
The Right

Long duration automobile-induced vibration is the cause of many ailments to humans. Predicting and mitigating these vibrations through seat requires a good model of seated human body. A good model is the one that strikes the right balance between modelling difficulty and simulation results accuracy. Increasing the number of body parts which have been separately modelled and increasing the number of ways these parts are connected to each other increase the number of degrees of freedom of the entire model. A number of such models have been reported in the literature. These range from simple lumped parameter models with limited accuracy to advanced models with high computational cost. However, a systematic comparison of these models has not been reported till date. This work creates eight such models ranging from 8 to 26 degrees of freedom and tries to identify the model which strikes the right balance between modelling complexity and results accuracy. A comparison of the models’ prediction with experimental data published in the literature allows the identification of a 12 degree of freedom backrest supported model as optimum for modelling complexity and prediction accuracy.

scholarly journals ON THE OCCURRENCE OF CATALASE IN HUMAN TISSUES AND ITS VARIATIONS IN DISEASES

1908 ◽  
Vol 10 (6) ◽  
pp. 759-781 ◽  
Author(s):  
M. C. Winternitz ◽  
C. R. Meloy
Keyword(s):  
Catalytic Activity ◽  
Clinical Symptoms ◽  
Congenital Syphilis ◽  
Marked Change ◽  
The Other ◽  
Human Tissues ◽  
Subsequent Work ◽  
Simple Method ◽  
The One ◽  
Increased Activity

1. In work along this line it is most important to have a simple method of determining the catalytic activity of tissues. The method must be such that several observations can be made during a single experiment, so that a better idea can be obtained of the velocity of the reaction at various intervals. 2. The catalytic activity of human tissues varies greatly in diseases. A. Nephritis.—The kidney always shows the most marked reduction although the other tissues examined, blood, lung, liver, spleen, likewise show decrease in their power of decomposing hydrogen peroxide. This reduction varies directly with the severity of the pathological lesion in the kidney and the clinical symptoms. The urine also in cases of nephritis shows a much greater inhibiting power than normal urine. This may be accounted for by the reaction of the urine, and subsequent work must prove whether or not the kidney takes any more active part in nephritis and secretes into the blood and urine a substance which manifests itself by a reduction in the catalytic activity. B. The catalytic activity of the blood in the two cases of eclampsia which we have studied was not reduced. This is the most important fact we have so far obtained, if it can be substantiated, since it can furnish us with a ready ante-mortem means of differentiating eclampsia and nephritis. C.Pneumonia.—The lung in the stage of red hepatization has an increased catalytic activity. This increase varies directly with the number of intact red blood cells in the exudate, and in the engorged capillaries. Strength is given to this conclusion by the fact, that on the one hand, there is no increased activity in gray hepatization, while on the other hand, there is an enormously increased activity in the fresh hemorrhagic infarct. D. Tuberculosis.—The decreased activity of the lung in tuberculosis is probably due, for the most part, to the lack of blood in the diseased area, while the lowered activity which is present in the other organs is to be explained by the anæmia and emaciation which accompanies the process. Whether there is a specific catalytic inhibiting substance generated by the process, has not been determined. E. There was no reduction of the catalytic activity in the cases of diabetes mellitus and jaundice studied. F. In the one case of asphyxiation by illuminating gas, there was decided decrease in the catalytic activity of the blood. G. The tissues in the one case of congenital syphilis showed a marked lowering of the catalytic activity. 3. There is a slight decrease in the catalytic activity of the tissues due to post-mortem change, but this is so slight that it is hardly to be taken into consideration in the interpretation of the results obtained. 4. There is no marked change in the catalytic activity due to age. In concluding, we wish to thank Dr. A. S. Loevenhart, at whose suggestion this enzyme was studied, for the unfailing interest with which he has followed the progress of this work, and for the many valuable suggestions he has given us.

scholarly journals STUDIES ON EXPERIMENTAL HYPERTENSION

1943 ◽  
Vol 77 (4) ◽  
pp. 297-307 ◽  
Author(s):  
Harry Goldblatt ◽  
Joseph R. Kahn ◽  
Harvey A. Lewis
Keyword(s):  
Blood Pressure ◽  
Renal Artery ◽  
Renal Hypertension ◽  
Renal Arteries ◽  
Experimental Hypertension ◽  
Long Duration ◽  
Humoral Mechanism ◽  
Main Renal Artery ◽  
Experimental Renal Hypertension ◽  
The One

Persistent hypertension has been produced in the goat and sheep by constriction of the main renal arteries. The presence or absence of accompanying uremia depends upon the degree of constriction of the renal arteries. In both sheep and goat, constriction of one main renal artery also caused elevation of the blood pressure which tended to persist longer than in the dog. Excision of the one kidney with main renal artery constricted resulted in a prompt (24 hours) return of the blood pressure to normal. In the animals with hypertension of long duration but without renal excretory insufficiency, (the "benign" phase) no significant arterio- or arteriolosclerosis developed as a result of the hypertension alone. In the animals that had both hypertension and renal excretory insufficiency, (the "malignant" phase) the typical terminal arteriolar lesions developed in many organs. These lesions consisted of necrosis and fibrinoid degeneration of arterioles and necrotizing arteriolitis which should not be confused with arteriolosclerosis. The same humoral mechanism which is responsible for experimental renal hypertension in the dog and other animals also obtains in the pathogenesis of experimental renal hypertension in the sheep and goat.

scholarly journals CONSUMPTION AND USE OF OXYGEN BY THE BODY OF PERSONS WITH CARDIOVASCULAR PATHOLOGY WITH CHANGES IN GEOMAGNETIC ACTIVITY

2021 ◽  
Vol 3 (1) ◽  
pp. 323-330
Author(s):  
Gennady A. Usenko ◽  
Dmitry V. Vasendin
Keyword(s):  
Solar Activity ◽  
Radio Emission ◽  
Arterial Hypertension ◽  
Air Temperature ◽  
Atmospheric Pressure ◽  
The Body ◽  
Emission Flux ◽  
Oxygen Utilization ◽  
Gamma Background ◽  
The One

The aim of the study was to identify and evaluate the relationship between the indicators of solar activity, the content of magnesium in the blood and the level of oxygen utilization by tissues in men with different temperaments and anxiety, suffering from arterial hypertension. During the period of the study from 1995 to 2015, sick and healthy men were divided into equal groups with a predominance of choleric, sanguine, phlegmatic and melancholic temperament with high and low anxiety. The average annual values of the Wolf numbers, the radio emission of the Sun at a wavelength of 10,7 cm, atmospheric pressure, gamma background and air temperature were taken into account, and the content of magnesium and hemoglobin in the blood serum was determined. The oxygen concentration was determined by the calculated method. A statistically significant direct correlation has been established between the increase in solar activity (Wolf numbers, radio emission flux at a wavelength of 10.7 cm), on the one hand, and atmospheric pressure, air temperature, and the gamma background of the environment, on the other. Under the same environmental conditions, the content of magnesium in the blood and the level of oxygen utilization by the body tissues of patients with arterial hypertension decreased in the temperamental range from high- and low-anxiety sympathotonics (choleric and sanguine) to parasympathotonics (high- and low-anxiety phlegmatic and melancholic). During the study period, a statistically significant relationship was established between an increase in solar activity (Wolf numbers, radio emission flux), atmospheric pressure, air temperature, and gamma background, on the one hand, and a decrease in the content of magnesium in the blood, as well as the level of oxygen utilization by tissues in healthy high- and low-anxiety individuals and patients with arterial hypertension, regardless of temperament.

scholarly journals Quantitative analysis of intermediary metabolism in rat hepatocytes incubated in the presence and absence of ethanol with a substrate mixture including ketoleucine

1989 ◽  
Vol 258 (1) ◽  
pp. 121-140 ◽  
Author(s):  
J M Baranyai ◽  
J J Blum
Keyword(s):  
Ketone Bodies ◽  
Rat Hepatocytes ◽  
Metabolic Model ◽  
Oxygen Utilization ◽  
Acetyl Coa ◽  
Atp Production ◽  
Considerable Excess ◽  
Metabolic Conditions ◽  
Label Incorporation

Hepatocytes isolated from livers of fed rats were incubated with a mixture of glucose (10 mM), ribose (1.0 mM), acetate (1.25 mM), alanine (3.5 mM), glutamate (2.0 mM), aspartate (2.0 mM), 4-methyl-2-oxovaleric acid (ketoleucine) (3.0 mM), and, in paired flasks, 10 mM-ethanol. One substrate was 14C-radiolabelled in any given incubation. Incorporation of 14C into glucose, glycogen, CO2, lactate, alanine, aspartate, glutamate, acetate, urea, lipid glycerol, fatty acids and the 1- and 2,3,4-positions of ketone bodies was measured after 20 and 40 min of incubation under quasi-steady-state conditions. Data were analysed with the aid of a realistic structural metabolic model. In each of the four conditions examined, there were approx. 77 label incorporation measurements and several measurements of changes in metabolite concentrations. The considerable excess of measurements over the 37 independent flux parameters allowed for a stringent test of the model. A satisfactory fit to these data was obtained for each condition. There were large bidirectional fluxes along the gluconeogenic/glycolytic pathways, with net gluconeogenesis. Rates of ureagenesis, oxygen consumption and ketogenesis were high under all four conditions studied. Oxygen utilization was accurately predicted by three of the four models. There was complete equilibration between mitochondrial and cytosolic pools of acetate and of CO2, but for several of the metabolic conditions, two incompletely equilibrated pools of mitochondrial acetyl-CoA and oxaloacetate were required. Ketoleucine was utilized at a rate comparable to that reported by others in perfused liver and entered the mitochondrial pool of acetyl-CoA directly associated with ketone body formation. Ethanol, which was metabolized at rates comparable to those in vivo, caused relatively few changes in overall flux patterns. Several effects related to the increased NADH/NAD+ ratio were observed. Pyruvate dehydrogenase was completely inhibited and the ratio of acetoacetate to 3-hydroxybutyrate was decreased; flux through glutamate dehydrogenase, the citric acid cycle, and ketoleucine dehydrogenase were, however, only slightly inhibited. Net production of ATP occurred in all conditions studied and was increased by ethanol. Futile cycling was quantified at the glucose/glucose 6-phosphate, glycogen/glucose 6-phosphate, fructose 6-phosphate/fructose 1,6-bis-phosphate, and phosphoenolpyruvate/pyruvate/oxaloacetate substrate cycles. Cycling at these four loci consumed about 22% of cellular ATP production in control hepatocytes and 14% in ethanol-treated cells.

scholarly journals ALCAT1 Overexpression Affects Supercomplex Formation and Increases ROS in Respiring Mitochondria

2019 ◽  
Vol 2019 ◽  
pp. 1-12 ◽  
Author(s):  
Bettina Rieger ◽  
Adéla Krajčová ◽  
Patrick Duwe ◽  
Karin B. Busch
Keyword(s):  
Electron Transport ◽  
Electron Transport Chain ◽  
High Variability ◽  
Ros Production ◽  
Metabolic Plasticity ◽  
Contact Sites ◽  
Chain Complexes ◽  
Mitochondrial Ros ◽  
Transport Chain ◽  
Metabolic Conditions

Cardiolipin (CL) is a multifunctional dimeric phospholipid that physically interacts with electron transport chain complexes I, III, and IV, and ATP synthase (complex V). The enzyme ALCAT1 catalyzes the conversion of cardiolipin by incorporating polyunsaturated fatty acids into cardiolipin. The resulting CL species are said to be more susceptible to oxidative damage. This is thought to negatively affect the interaction of cardiolipin and electron transport chain complexes, leading to increased ROS production and mitochondrial dysfunction. Furthermore, it is discussed that ALCAT1 itself is upregulated due to oxidative stress. Here, we investigated the effects of overexpression of ALCAT1 under different metabolic conditions. ALCAT1 is located at the ER and mitochondria, probably at contact sites. We found that respiration stimulated by galactose supply promoted supercomplex assembly but also led to increased mitochondrial ROS levels. Endogeneous ALCAT1 protein expression levels showed a fairly high variability. Artificially induced ALCAT1 overexpression reduced supercomplex formation, further promoted ROS production, and prevented upregulation of coupled respiration. Taken together, our data suggest that the amount of the CL conversion enzyme ALCAT1 is critical for coupling mitochondrial respiration and metabolic plasticity.

scholarly journals Opposite response of blood vessels in the retina to 6° head-down tilt and long-duration microgravity

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Giovanni Taibbi ◽  
Millennia Young ◽  
Ruchi J. Vyas ◽  
Matthew C. Murray ◽  
Shiyin Lim ◽  
...  
Keyword(s):  
Space Station ◽  
Bed Rest ◽  
Vascular Density ◽  
Vascular Response ◽  
Mixed Effects Modeling ◽  
Long Duration ◽  
Fluid Shifts ◽  
Before And After ◽  
And Performance ◽  
The One

AbstractThe Spaceflight Associated Neuro-ocular Syndrome (SANS), associated with the headward fluid shifts incurred in microgravity during long-duration missions, remains a high-priority health and performance risk for human space exploration. To help characterize the pathophysiology of SANS, NASA’s VESsel GENeration Analysis (VESGEN) software was used to map and quantify vascular adaptations in the retina before and after 70 days of bed rest at 6-degree Head-Down Tilt (HDT), a well-studied microgravity analog. Results were compared to the retinal vascular response of astronauts following 6-month missions to the International Space Station (ISS). By mixed effects modeling, the trends of vascular response were opposite. Vascular density decreased significantly in the 16 retinas of eight astronauts and in contrast, increased slightly in the ten retinas of five subjects after HDT (although with limited significance). The one astronaut retina diagnosed with SANS displayed the greatest vascular loss. Results suggest that microgravity is a major variable in the retinal mediation of fluid shifts that is not reproduced in this HDT bed rest model.

Weekly Bone Loading Exercise Effects on a Healthy Subjects Strength, Bone Density, and Bone Biomarkers

2021 ◽  
Vol 92 (3) ◽  
pp. 201-206
Author(s):  
Ann Tsung ◽  
Daniel Jupiter ◽  
John Jaquish ◽  
Jean Sibonga
Keyword(s):  
Bone Density ◽  
Healthy Subjects ◽  
Whole Body ◽  
Bone Biomarkers ◽  
Mineral Density ◽  
Long Duration ◽  
Bone Loading ◽  
The Subject ◽  
The One ◽  
Increased Strength

BACKGROUND: Bone density loss affects astronauts in long-duration spaceflight. The OsteoStrong Company has shown increased hip (14.95%) and lumbar (16.6%) area bone mineral density (aBMD) after 6 mo of exercises with their loading devices. The devices were tested on one subject as a pilot study.CASE REPORT: The subject performed 15 min of osteogenic exercises weekly for 24 wk. Total and regional aBMD, BAP (bone formation biomarker), NTX (bone resorption biomarker), forces exerted on devices, and weekly maximum weights lifted were collected. The control data was the subjects own lifting records 1.5 yr prestudy. The subject increased forces exerted on the devices in the upper extremity (97%, 197 to 390 kg; 435 to 859 lb), lower extremity (43%, 767 to 1097 kg; 1690 to 2418 lb), and spinal compression (22%, 275 to 336 kg; 607 to 740 lb). The monthly strength gain rate increased for snatch (2.3 vs. 0.71 kg; 5 vs. 1.56 lb), clean and jerk (2.5 vs. 0.4 kg; 5.5 vs. 0.88 lb), back squat (3.74 vs. 0 kg; 8.25 vs. 0 lb), front squat (2.15 vs. 0.2 kg; 4.75 vs. 0.47 lb), and deadlift (3.97 vs. 1.09 kg; 8.75 vs. 2.4 lb). The BAP increased by 39% (10.4 to 14.5 4 ug L1) and NTX decreased by 41% (13.4 to 7 nmol L1 BME). aBMD increased in the head (6%), arms (4.3%), trunk (6.3%), ribs (3.8%), and pelvis (11%). There were no differences in body weight, legs, spine, and whole-body aBMD on the full-body dual-energy X-ray absorptiometry (DXA). There were no differences in lumbar, hip, and femoral neck aBMD on the regional DXA.DISCUSSION: The osteogenic loading apparatus used for 15 min weekly increased strength for the one individual in this preliminary study. Future studies on astronauts and other healthy populations are necessary.Tsung A, Jupiter D, Jaquish J, Sibonga J. Weekly bone loading exercise effects on a healthy subjects strength, bone density, and bone biomarkers. Aerosp Med Hum Perform. 2021;92(3):201206.

Slavery, Indenture and the Development of British Industrial Capitalism

2019 ◽  
Vol 88 ◽  
pp. 66-88 ◽  
Author(s):  
Mark Harvey
Keyword(s):  
Industrial Revolution ◽  
Central Feature ◽  
Deep South ◽  
Industrial Capitalism ◽  
Indentured Servitude ◽  
Wage Labour ◽  
Long Duration ◽  
Epochal Change ◽  
Market Wage ◽  
The One

Abstract The paper addresses the central issue of the relationship between slavery and industrial capitalism. It does so by re-examining Eric Williams’s classic account and recent debates related to it on the one hand, and on the other, by challenging basic assumptions about capitalism as a closed market-wage labour-capital system. Taking a long-duration approach (from the mid eighteenth century to the end of the nineteenth century) to three key commodities – guns, sugar and cotton – the paper argues that British industrial capitalism drove the expansion of slavery and then other regimes of exploitation in a dynamic and interdependent relationship with the transformation of the metropolitan wage economy. The analysis is based on changing configurations of production-exchange-distribution-consumption for each of these three exemplary commodities. The British industrial revolution is thus characterized by its hybridity and heterogeneity, always combining varied regimes of exploitation: metropolitan wage labour, directly-owned British Caribbean and Mauritian slavery, and US Deep South slavery, each followed by varied transitions to indentured servitude or sharecropping. New and contrasting racialized orders of hierarchy and inequality emerged and were entrenched as a central feature of this epochal change, the legacies of which are only too present today.

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