Computer modeling of the oxygen supply and demand of cells of the avian growth cartilage

1993 ◽  
Vol 265 (2) ◽  
pp. C497-C506 ◽  
Author(s):  
J. C. Haselgrove ◽  
I. M. Shapiro ◽  
S. F. Silverton
Keyword(s):  
Oxygen Consumption ◽  
Blood Vessels ◽  
Computer Modeling ◽  
Growth Plate ◽  
Oxygen Supply ◽  
Supply And Demand ◽  
Protective Mechanism ◽  
Low Oxygen ◽  
Growth Cartilage ◽  
Oxygen Tensions

We have used computer modeling studies to investigate the oxygen supply to the prehypertrophic and hypertrophic regions of avian growth plate. We measured experimentally the characteristics of the oxygen consumption of chondrocytes at different oxygen tensions. The oxygen consumption decreases at low oxygen tensions. This relation between oxygen tension and oxygen consumption serves as a protective mechanism that prevents the cells in the prehypertrophic zone from becoming anoxic in the regions farthest from the blood vessels. The results of the calculations, when combined with redox measurements of the cells in the growth plate, indicate that the metabolism of the chondrocytes is not controlled simply by the available oxygen supply.

Respiration and biometry in the sea cucumber Holothuria forskali

1991 ◽  
Vol 71 (1) ◽  
pp. 73-81 ◽  
Author(s):  
C. M. Astall ◽  
M. B. Jones
Keyword(s):  
Body Weight ◽  
Oxygen Consumption ◽  
Sea Cucumber ◽  
Regression Line ◽  
Weight Ratio ◽  
Mechanical Trauma ◽  
Low Oxygen ◽  
Sea Cucumbers ◽  
Oxygen Tensions ◽  
Respiratory Trees

Relationships between wet body weight, dry body weight and ash-free dry body weight (AFDW) were established for the aspidochirote sea cucumber Holothuria forskali (Echinodermata: Holothuroidea); a wetdry weight ratio of 6–38:1 was found. Length-weight relations were also determined. Low oxygen tensions and mechanical trauma induced H. forskali to eviscerate (70% of individuals tested). Respiratory measurements of intact and eviscerated sea cucumbers were determined at 17°C. For intact animals, oxygen consumption (ul h1) was directly related to AFDW (the slope of the regression line, b=0–60), whereas weight-specific oxygen consumption (Vo2; ul g1AFDW h) was inversely related to AFDW (b=0–54). Oxygen consumption of eviscerated sea cucumbers was independent of AFDW (b=0-\5), but Vo 2 was inversely related to AFDW (t–0–85). There were no significant differences between the respiratory rates of intact and eviscerated individuals, indicating that H. forskali is not so dependent upon respiratory trees for oxygen uptake as previously assumed.

scholarly journals NADH changes during hypoxia, ischemia, and increased work differ between isolated heart preparations

2014 ◽  
Vol 306 (4) ◽  
pp. H529-H537 ◽  
Author(s):  
Anastasia M. Wengrowski ◽  
Sarah Kuzmiak-Glancy ◽  
Rafael Jaimes ◽  
Matthew W. Kay
Keyword(s):  
Energy Supply ◽  
Oxygen Supply ◽  
Heart Function ◽  
Isolated Heart ◽  
Supply And Demand ◽  
Half Maximum ◽  
Low Oxygen ◽  
Heart Preparation ◽  
Perfused Hearts

Langendorff-perfused hearts and working hearts are established isolated heart preparation techniques that are advantageous for studying cardiac physiology and function, especially when fluorescence imaging is a key component. However, oxygen and energy requirements vary widely between isolated heart preparations. When energy supply and demand are not in harmony, such as when oxygen is not adequately available, the imbalance is reflected in NADH fluctuations. As such, NADH imaging can provide insight into the metabolic state of tissue. Hearts from New Zealand white rabbits were prepared as mechanically silenced Langendorff-perfused hearts, Langendorff-perfused hearts, or biventricular working hearts and subjected to sudden changes in workload, instantaneous global ischemia, and gradual hypoxia while heart rate, aortic pressure, and epicardial NADH fluorescence were monitored. Fast pacing resulted in a dip in NADH upon initiation and a spike in NADH when pacing was terminated in biventricular working hearts only, with the magnitude of the changes greatest at the fastest pacing rate. Working hearts were also most susceptible to changes in oxygen supply; NADH was at half-maximum value when perfusate oxygen was at 67.8 ± 13.7%. Langendorff-perfused and mechanically arrested hearts were the least affected by low oxygen supply, with half-maximum NADH occurring at 42.5 ± 5.0% and 23.7 ± 4.6% perfusate oxygen, respectively. Although the biventricular working heart preparation can provide a useful representation of mechanical in vivo heart function, it is not without limitations. Understanding the limitations of isolated heart preparations is crucial when studying cardiac function in the context of energy supply and demand.

scholarly journals The Respiration of Freshwater Snails

1959 ◽  
Vol 36 (4) ◽  
pp. 690-708
Author(s):  
KAJ BERG ◽  
K. W. OCKELMANN
Keyword(s):  
Oxygen Consumption ◽  
Body Size ◽  
Oxygen Content ◽  
Oxygen Supply ◽  
Regression Line ◽  
Live Weight ◽  
Interspecific Variation ◽  
Freshwater Snails ◽  
Low Oxygen ◽  
Bithynia Tentaculata

1. The oxygen consumption of some Danish freshwater snails was studied in relation to varying periods of starvation, varying temperatures, weight of animals and oxygen content of the water. The observed respiration is a moderately active metabolism, not a basal one. 2. In the case of Lymnaea palustris and Bithynia leachi a distinct decrease of oxygen consumption has been found in the period 1-24 hr. after collecting; the decrease is supposed to be caused by starvation. In similar experiments Lymnaea pereger, Myxas giutinosa, Bithynia tentaculata, Valvata piscinalis and possibly Physafontinalis and Lymnaea auricularia show only a small decrease (or no decrease) of oxygen consumption. 3. During a gradual increase of the temperature (c. I° C. per hr.) the snails increase their oxygen consumption by 65-90% of the increase expected from Krogh's curve. In the case of Myxas glutinosa and Physa fontinalis the increase of respiration was nearly the same as that found by Krogh for other animals. 4. The relation of oxygen consumption to body size (live weight) is not a fixed, unchangeable quantity characteristic of every species, but may vary seasonally. A tentative explanation of this variation is given. 5. The oxygen consumption in relation to body size has also an interspecific variation. In prosobranchs the slopes b of the regression lines in a logarithmic co-ordinate system have in some cases nearly the magnitude 0.67 required by the surface law, but others are higher, e.g. c. 0.95. In pulmonates the relation varies as much as from b=c. 0.45 to b=c. 1.00, i.e. between less than proportional to surface and proportional to weight. 6. The oxygen consumption of the freshwater snails in relation to the sizes of the standard individuals is depicted in a logarithmic co-ordinate system as a belt showing only a slight deviation (Fig. 4, p. 697), i.e. the snails regarded as a whole have a fairly uniform respiration. The regression line of oxygen consumption to sizes of the standard individuals seems to be expressed by a regression line with a slope just under 1.0. 7. Experiments on oxygen consumption in relation to oxygen content of the water have shown that some species (Lymnaea auricularia, Myxas glutinosa, Physafontinalis, Valvata piscinalis and Bithynia leachi) are able to maintain their consumption with decreasing oxygen content of the water to a critical point of oxygen supply. But in some other species (Lymnaea pereger, L. palustris and Bithynia tentaculata) oxygen consumption decreases immediately in response to a declining oxygen supply. 8. In some freshwater snails (Myxas glutinosa, Lymnaea pereger, Physa fontinalis) the decrease in oxygen consumption in response to a decreasing oxygen supply is not gradual, but shows a steep fall below certain low values of the oxygen content. The only species able to maintain a comparatively high oxygen consumption at low oxygen supply is Bithynia leachi.

Sensitivity of malaria parasites to nitric oxide at low oxygen tensions

The Lancet ◽  
1998 ◽  
Vol 351 (9116) ◽  
pp. 1630 ◽  
Author(s):  
AW Taylor-Robinson ◽  
M Looker
Keyword(s):  
Nitric Oxide ◽  
Low Oxygen ◽  
Malaria Parasites ◽  
Oxygen Tensions

scholarly journals Oxygen saturations of medical inpatients in a Malawian hospital: cross-sectional study of oxygen supply and demand

Pneumonia ◽  
2012 ◽  
Vol 1 (1) ◽  
pp. 3-6 ◽  
Author(s):  
Hywel-Gethin Tudur Evans ◽  
Nadia Mahmood ◽  
Duncan G. Fullerton ◽  
Jamie Rylance ◽  
Andrew Gonani ◽  
...  
Keyword(s):  
Oxygen Supply ◽  
Supply And Demand ◽  
Cross Sectional Study ◽  
Sectional Study ◽  
Cross Sectional ◽  
Medical Inpatients

Weight loading young chicks inhibits bone elongation and promotes growth plate ossification and vascularization

2005 ◽  
Vol 98 (6) ◽  
pp. 2381-2389 ◽  
Author(s):  
A. Reich ◽  
N. Jaffe ◽  
A. Tong ◽  
I. Lavelin ◽  
O. Genina ◽  
...  
Keyword(s):  
Blood Vessels ◽  
Growth Plate ◽  
Developmental Process ◽  
Mechanical Strain ◽  
Cell Counting ◽  
Mechanical Stimuli ◽  
Growth Plates ◽  
Average Width ◽  
The Matrix ◽  
Weight Loading

The mechanical stimuli resulting from weight loading play an important role in mature bone remodeling. However, the effect of weight loading on the developmental process in young bones is less well understood. In this work, chicks were loaded with bags weighing 10% of their body weight during their rapid growth phase. The increased load reduced the length and diameter of the long bones. The average width of the bag-loaded group's growth plates was 75 ± 4% that of the controls, and the plates showed increased mineralization. Northern blot analysis, in situ hybridization, and longitudinal cell counting of mechanically loaded growth plates showed narrowed expression zones of collagen types II and X compared with controls, with no differences between the relative proportions of those areas. An increase in osteopontin (OPN) expression with loading was most pronounced at the bone-cartilage interface. This extended expression overlapped with tartarate-resistant acid phosphatase staining and with the front of the mineralized matrix in the chondro-osseous junction. Moreover, weight loading enhanced the penetration of blood vessels into the growth plates and enhanced the gene expression of the matrix metalloproteinases MMP9 and MMP13 in those growth plates. On the basis of these results, we speculate that the mechanical strain on the chondrocytes in the growth plate causes overexpression of OPN, MMP9, and MMP13. The MMPs enable penetration of the blood vessels, which carry osteoclasts and osteoblasts. OPN recruits the osteoclasts to the cartilage-bone border, thus accelerating cartilage resorption in this zone and subsequent ossification which, in turn, contributes to the observed phenotype of narrower growth plate and shorter bones.

scholarly journals The Hypoxic Testicle: Physiology and Pathophysiology

2012 ◽  
Vol 2012 ◽  
pp. 1-15 ◽  
Author(s):  
Juan G. Reyes ◽  
Jorge G. Farias ◽  
Sebastián Henríquez-Olavarrieta ◽  
Eva Madrid ◽  
Mario Parraga ◽  
...  
Keyword(s):  
Germ Cell ◽  
Testicular Torsion ◽  
Oxygen Supply ◽  
Cell Function ◽  
Cell Damage ◽  
The Body ◽  
Body Core Temperature ◽  
Seminiferous Tubules ◽  
Low Oxygen ◽  
Complex Biological Process

Mammalian spermatogenesis is a complex biological process occurring in the seminiferous tubules in the testis. This process represents a delicate balance between cell proliferation, differentiation, and apoptosis. In most mammals, the testicles are kept in the scrotum 2 to 7°C below body core temperature, and the spermatogenic process proceeds with a blood and oxygen supply that is fairly independent of changes in other vascular beds in the body. Despite this apparently well-controlled local environment, pathologies such as varicocele or testicular torsion and environmental exposure to low oxygen (hypoxia) can result in changes in blood flow, nutrients, and oxygen supply along with an increased local temperature that may induce adverse effects on Leydig cell function and spermatogenesis. These conditions may lead to male subfertility or infertility. Our literature analyses and our own results suggest that conditions such as germ cell apoptosis and DNA damage are common features in hypoxia and varicocele and testicular torsion. Furthermore, oxidative damage seems to be present in these conditions during the initiation stages of germ cell damage and apoptosis. Other mechanisms like membrane-bound metalloproteinases and phospholipase A2 activation could also be part of the pathophysiological consequences of testicular hypoxia.

Cerebral sympathetic nerve activity has a major regulatory role in the cerebral circulation in REM sleep

2009 ◽  
Vol 106 (4) ◽  
pp. 1050-1056 ◽  
Author(s):  
Priscila A. Cassaglia ◽  
Robert I. Griffiths ◽  
Adrian M. Walker
Keyword(s):  
Arterial Pressure ◽  
Blood Vessels ◽  
Rem Sleep ◽  
Sympathetic Nerve ◽  
Cerebral Circulation ◽  
Sympathetic Nerve Activity ◽  
Nrem Sleep ◽  
Protective Mechanism ◽  
Nerve Activity ◽  
Phasic Rem Sleep

Sympathetic nerve activity (SNA) in neurons projecting to skeletal muscle blood vessels increases during rapid-eye-movement (REM) sleep, substantially exceeding SNA of non-REM (NREM) sleep and quiet wakefulness (QW). Similar SNA increases to cerebral blood vessels may regulate the cerebral circulation in REM sleep, but this is unknown. We hypothesized that cerebral SNA increases during phasic REM sleep, constricting cerebral vessels as a protective mechanism against cerebral hyperperfusion during the large arterial pressure surges that characterize this sleep state. We tested this hypothesis using a newly developed model to continuously record SNA in the superior cervical ganglion (SCG) before, during, and after arterial pressure surges occurring during REM in spontaneously sleeping lambs. Arterial pressure (AP), intracranial pressure (ICP), cerebral blood flow (CBF), cerebral vascular resistance [CVR = (AP − ICP)/CBF], and SNA from the SCG were recorded in lambs ( n = 5) undergoing spontaneous sleep-wake cycles. In REM sleep, CBF was greatest (REM > QW = NREM, P < 0.05) and CVR was least (REM < QW = NREM, P < 0.05). SNA in the SCG did not change from QW to NREM sleep but increased during tonic REM sleep, with a further increase during phasic REM sleep (phasic REM > tonic REM > QW = NREM, P < 0.05). Coherent averaging revealed that SNA increases preceded AP surges in phasic REM sleep by 12 s ( P < 0.05). We report the first recordings of cerebral SNA during natural sleep-wake cycles. SNA increases markedly during tonic REM sleep, and further in phasic REM sleep. As SNA increases precede AP surges, they may serve to protect the brain against potentially damaging intravascular pressure changes or hyperperfusion in REM sleep.

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