scholarly journals Arabidopsis plants perform arithmetic division to prevent starvation at night

eLife ◽  
2013 ◽  
Vol 2 ◽  
Author(s):  
Antonio Scialdone ◽  
Sam T Mugford ◽  
Doreen Feike ◽  
Alastair Skeffington ◽  
Philippa Borrill ◽  
...  
Keyword(s):  
Biological System ◽  
Kinetic Models ◽  
Starch Content ◽  
Chemical Kinetic ◽  
Light Period ◽  
Starch Degradation ◽  
Degradation Pathways ◽  
Night Time ◽  
Expected Time ◽  
Time Period

Photosynthetic starch reserves that accumulate in Arabidopsis leaves during the day decrease approximately linearly with time at night to support metabolism and growth. We find that the rate of decrease is adjusted to accommodate variation in the time of onset of darkness and starch content, such that reserves last almost precisely until dawn. Generation of these dynamics therefore requires an arithmetic division computation between the starch content and expected time to dawn. We introduce two novel chemical kinetic models capable of implementing analog arithmetic division. Predictions from the models are successfully tested in plants perturbed by a night-time light period or by mutations in starch degradation pathways. Our experiments indicate which components of the starch degradation apparatus may be important for appropriate arithmetic division. Our results are potentially relevant for any biological system dependent on a food reserve for survival over a predictable time period.

Fever in pregnant, parturient, and lactating rats

1995 ◽  
Vol 268 (4) ◽  
pp. R919-R923 ◽  
Author(s):  
S. M. Martin ◽  
T. J. Malkinson ◽  
W. L. Veale ◽  
Q. J. Pittman
Keyword(s):  
Escherichia Coli ◽  
Pregnant Rats ◽  
Expected Time ◽  
Time Period ◽  
Toxic Responses

Conscious virgin, pregnant, or lactating rats were given intravenous Escherichia coli endotoxin while their temperatures were monitored telemetrically. Virgin females responded to 10-50 micrograms/kg endotoxin with a slight hypothermia, followed by a fever of nearly 2 degrees C magnitude. In pregnant rats given 25 micrograms/kg of the endotoxin, fevers were reduced between 96 h before and 24 h after parturition compared with those seen in virgins or in lactating rats > 24 h postpartum. In the 24-h period before expected time of parturition, no rat developed a fever and the majority of animals became hypothermic; furthermore, in 80% of such animals given 25 micrograms/kg endotoxin, the hypothermia was accompanied by death within 3-15 h. Some mortality and hypothermia were also seen up to 48 h before birth and up to 24 h after birth. No mortality was observed in virgin, pregnant, or lactating rats outside of this time period. We conclude that, around the time of delivery, there is a suppression of fever in the rat and occasional toxic responses to endotoxin.

scholarly journals Combined Aerobic and Resistance Exercises Evokes Longer Reductions on Ambulatory Blood Pressure in Resistant Hypertension: A Randomized Crossover Trial

2020 ◽  
Vol 2020 ◽  
pp. 1-11 ◽  
Author(s):  
Nayara Fraccari Pires ◽  
Helio José Coelho-Júnior ◽  
Bruno Bavaresco Gambassi ◽  
Ana Paula Cabral de Faria ◽  
Alessandra Mileni Versuti Ritter ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Resistant Hypertension ◽  
Crossover Trial ◽  
Experimental Session ◽  
Acute Effects ◽  
Night Time ◽  
Randomized Crossover Trial ◽  
Time Period ◽  
Resistance Exercises ◽  
Postexercise Hypotension

Aim. The present study compared the acute effects of aerobic (AER), resistance (RES), and combined (COM) exercises on blood pressure (BP) levels in people with resistant hypertension (RH) and nonresistant hypertension (NON-RH). Methods. Twenty patients (10 RH and 10 NON-RH) were recruited and randomly performed three exercise sessions and a control session. Ambulatory BP was monitored over 24 hours after each experimental session. Results. Significant reductions on ambulatory BP were found in people with RH after AER, RES, and COM sessions. Notably, ambulatory BP was reduced during awake-time and night-time periods after COM. On the other hand, the effects of AER were more prominent during awake periods, while RES caused greater reductions during the night-time period. In NON-RH, only RES acutely reduced systolic BP, while diastolic BP was reduced after all exercise sessions. However, the longest postexercise ambulatory hypotension was observed after AER (~11 h) in comparison to RES (~8 h) and COM (~4 h) exercises. Conclusion. Findings of the present study indicate that AER, RES, and COM exercises elicit systolic and diastolic postexercise ambulatory hypotension in RH patients. Notably, longer hypotension periods were observed after COM exercise. In addition, NON-RH and RH people showed different changes on BP after exercise sessions, suggesting that postexercise hypotension is influenced by the pathophysiological bases of hypertension.

Restrictions on chemical kinetic models

1976 ◽  
Vol 65 (1) ◽  
pp. 284-292 ◽  
Author(s):  
David Wallwork ◽  
Alan S. Perelson
Keyword(s):  
Kinetic Models ◽  
Chemical Kinetic

Computer Construction of Detailed Chemical Kinetic Models for Gas-Phase Reactors

2001 ◽  
Vol 40 (23) ◽  
pp. 5362-5370 ◽  
Author(s):  
W. H. Green ◽  
P. I. Barton ◽  
B. Bhattacharjee ◽  
D. M. Matheu ◽  
D. A. Schwer ◽  
...  
Keyword(s):  
Gas Phase ◽  
Kinetic Models ◽  
Chemical Kinetic ◽  
Detailed Chemical

P3754Comparison of the transdermal bisoprolol patch with the oral bisoprolol fumarate administration as a therapeutic agent for idiopathic frequent premature ventricular contractions

2019 ◽  
Vol 40 (Supplement_1) ◽  
Author(s):  
M Shinohara ◽  
R Wada ◽  
K Akitsu ◽  
T Kinoshita ◽  
H Yuzawa ◽  
...  
Keyword(s):  
Therapeutic Agent ◽  
Group Differences ◽  
Night Time ◽  
Premature Ventricular Contractions ◽  
Duration Of Action ◽  
Time Period ◽  
Significant Difference ◽  
The Mean ◽  
Initiation Of Therapy ◽  
The Relationship

Abstract Background The transdermal bisoprolol patch (TB) was designed to maintain a sustained concentration of bisoprolol in plasma by higher trough concentration than the oral bisoporolol fumarate administration (OB). It is unclear whether the TB is as effective in treating idiopathic premature ventricular contractions (PVCs) as the OB. Purpose We compared the efficacy between the TB and OB in treating idiopathic PVCs while considering their duration of action. Methods Among 198 patients with a PVC count of ≥3,000 beats/24 hours, 84 patients were divided into groups treated with TB 4mg (n=50) or OB 2.5mg (n=34). The PVCs were divided into positive heart rate (HR)-dependent PVCs (P-PVCs) and non-positive HR-dependent PVCs (NP-PVCs) based on the relationship between the hourly PVCs density and hourly mean HR. To evaluate the efficacy, PVC counts by 24-hour Holter electrocardiograms were measured at baseline and at 1 month after the initiation of the therapy. Results There were no significant between-group differences for the mean HR, PVC count, or type of PVCs. Both the TB (from 16,692±9,737 to 10,442±10,711 beats/24 hours, P<0.001) and OB (from 19,633±16,298 to 9,235±12,124 beats/24 hours, P<0.001) significantly decreased the total PVC count after the initiation of therapy, and a comparison between the two drugs showed no significant difference (P=0.46). In the P-PVC group, both the TB and OB significantly decreased the total PVC count (P<0.001, P=0.022 respectively), PVC count during the day-time (P<0.001, P=0.030 respectively), and PVC count during the night-time (P=0.0038, P=0.022 respectively). In contrast, in the NP-PVC group, neither the TB nor OB made any significantly change in the total PVC count (P=0.079, P=0.10 respectively), PVC count during the day-time (P=0.35, P=0.12 respectively), or PVC count during the night-time (P=0.11, P=0.12 respectively). The TB exhibited a significant reduction during each time period regarding the changes within 24-hours in the P-PVC count from baseline, while the OB did not significantly reduce the P-PVC count from baseline during each time period between 0 and 5 o'clock. Conclusions Compared with the OB, the TB could be used with the same efficacy for reducing the PVC count. The TB could be a more useful therapeutic agent for idiopathic P-PVCs during a 24-hour period than the OB.

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