scholarly journals A model for measurement of lactate disappearance with isotopic tracers in the steady state

1988 ◽  
Vol 256 (3) ◽  
pp. 1035-1038 ◽  
Author(s):  
W C Stanley ◽  
S L Lehman
Keyword(s):  
Steady State ◽  
Infusion Rate ◽  
Specific Radioactivity ◽  
Compartment Model ◽  
The Body ◽  
Total Carbon ◽  
Isotopic Tracers ◽  
Arterial Lactate ◽  
Lactate And Pyruvate ◽  
Almost All

1. The irreversible disappearance of lactate carbon from the body (RdL) is commonly calculated from data obtained with a continuous infusion of isotopically labelled lactate tracer. The tracer infusion rate divided by the steady-state lactate specific radioactivity in blood is taken to give the rate of lactate disappearance. 2. Measurement of lactate disappearance is complicated by the fact that it is reversibly converted into pyruvate as well as being irreversibly removed from the system. 3. We analysed a four-compartment model of lactate metabolism, representing blood lactate, tissue lactate and pyruvate carbon pools. 4. The standard method of calculating RdL from the lactate tracer infusion rate divided by the specific radioactivity of lactate was not validated. 5. We found that RdL can be calculated from the infusion rate and the pyruvate specific radioactivity, multiplied by the fraction of the total carbon flow out of pyruvate that goes to lactate. 6. Therefore, if almost all of the pyruvate carbon flows back to lactate, then RdL approaches the tracer infusion rate divided by the pyruvate specific radioactivity. On the other hand, if the rate of oxidation is large in relation to the rate of pyruvate conversion into lactate, than RdL is overestimated when calculated from the pyruvate specific radioactivity. 7. Calculation of RdL with the arterial lactate specific radioactivity results in an underestimate of the true RdL.

scholarly journals Metabolism of 3H- and 14C-labelled lactate in starved rats

1981 ◽  
Vol 194 (2) ◽  
pp. 525-540 ◽  
Author(s):  
Fumikazu Okajima ◽  
Maymie Chenoweth ◽  
Robert Rognstad ◽  
Arnold Dunn ◽  
Joseph Katz
Keyword(s):  
Amino Acids ◽  
Steady State ◽  
Transit Time ◽  
Bolus Injection ◽  
Mean Transit Time ◽  
Specific Radioactivity ◽  
Vena Cava ◽  
The Body ◽  
Replacement Rate ◽  
Kinetics Of

1. [2-3H,U-14C]- or [3-3H,U-14C]-Lactate was administered by infusion or bolus injection to overnight-starved rats. Tracer lactate was injected or infused through indwelling cannulas into the aorta and blood was sampled from the vena cava (A–VC mode), or it was administered into the vena cava and sampled from the aorta (V–A mode). Sampling was continued after infusion was terminated to obtain the wash-out curves for the tracer. The activities of lactate, glucose, amino acids and water were followed. 2. The kinetics of labelled lactate in the two modes differed markedly, but the kinetics of labelled glucose were much the same irrespective of mode. 3. The kinetics of 3H-labelled lactate differed markedly from those for [U-14C]lactate. Isotopic steady state was attained in less than 1h of infusion of [3H]lactate but required over 6h for [U-14C]lactate. 4. 3H from [2-3H]lactate labels glucose more extensive than does that from [3-3H]lactate. [3-3H]Lactate also labels plasma amino acids. The distribution of 3H in glucose was determined. 5. Maximal radioactivity in 3HOH in plasma is attained in less than 1min after injection. Near-maximal radioactivity in [14C]glucose and [3H]glucose is attained within 2–3min after injection. 6. The apparent replacement rates for lactate were calculated from the areas under the specific-radioactivity curves or plateau specific radioactivities after primed infusion. Results calculated from bolus injection and infusion agreed closely. The apparent replacement rate for [3H]lactate from the A–VC mode averaged about 16mg/min per kg body wt. and that in the V–A mode about 8.5mg/min per kg body wt. The apparent rates for [14C]lactate (‘rate of irreversible disposal’) were 8mg/min per kg body wt. for the A–VC mode and 5.5mg/min per kg body wt. for the V–A mode. Apparent recycling of lactate carbon was 55–60% according to the A–VC mode and 35% according to the V–A mode. 7. The specific radioactivities of [U-14C]glucose at isotopic steady state were 55% and 45% that of [U-14C]lactate in the A–VC and V–A modes respectively. We calculated, correcting for the dilution of 14C in gluconeogenesis via oxaloacetate, that over 70% of newly synthesized glucose was derived from circulating lactate. 8. Recycling of 3H between lactate and glucose was evaluated. It has no significant effect on the calculation of the replacement rate, but affects considerably the areas under the wash-out curves for both [2-3H]- and [3-3H]-lactate, and calculation of mean transit time and total lactate mass in the body. Corrected for recycling, in the A–VC mode the mean transit time is about 3min, the lactate mass about 50mg/kg body wt. and the lactate space about 65% of body space. The V–A mode yields a mass and lactate space about half those with the A–VC mode. 9. The area under the wash-out curve for [14C]lactate is some 20–30 times that for [3H]lactate, and apparent carbon mass is 400–500mg/kg body wt. and presumably includes the carbon of glucose, pyruvate and amino acids, which are exchanging rapidly with that of lactate.

Influence of stable iodine on the uptake of the thyroid – model vs. experiment

2001 ◽  
Vol 40 (01) ◽  
pp. 31-37 ◽  
Author(s):  
U. Wellner ◽  
E. Voth ◽  
H. Schicha ◽  
K. Weber
Keyword(s):  
Time Course ◽  
Compartment Model ◽  
The Body ◽  
Iodine Uptake ◽  
Model Calculations ◽  
Physiological Conditions ◽  
Iodine Supply ◽  
Predicted Values ◽  
The Individual ◽  
Stable Iodine

Summary Aim: The influence of physiological and pharmacological amounts of iodine on the uptake of radioiodine in the thyroid was examined in a 4-compartment model. This model allows equations to be derived describing the distribution of tracer iodine as a function of time. The aim of the study was to compare the predictions of the model with experimental data. Methods: Five euthyroid persons received stable iodine (200 μg, 10 mg). 1-123-uptake into the thyroid was measured with the Nal (Tl)-detector of a body counter under physiological conditions and after application of each dose of additional iodine. Actual measurements and predicted values were compared, taking into account the individual iodine supply as estimated from the thyroid uptake under physiological conditions and data from the literature. Results: Thyroid iodine uptake decreased from 80% under physiological conditions to 50% in individuals with very low iodine supply (15 μg/d) (n = 2). The uptake calculated from the model was 36%. Iodine uptake into the thyroid did not decrease in individuals with typical iodine supply, i.e. for Cologne 65-85 μg/d (n = 3). After application of 10 mg of stable iodine, uptake into the thyroid decreased in all individuals to about 5%, in accordance with the model calculations. Conclusion: Comparison of theoretical predictions with the measured values demonstrated that the model tested is well suited for describing the time course of iodine distribution and uptake within the body. It can now be used to study aspects of iodine metabolism relevant to the pharmacological administration of iodine which cannot be investigated experimentally in humans for ethical and technical reasons.

Continuous Estimation of CO2 Production during Exercise

1997 ◽  
Vol 36 (04/05) ◽  
pp. 368-371
Author(s):  
R. Soma ◽  
Y. Yamamoto
Keyword(s):  
Fuzzy Logic ◽  
Steady State ◽  
Infusion Rate ◽  
Feedback System ◽  
Whole Body ◽  
Co2 Production ◽  
Cycle Exercise ◽  
Continuous Estimation ◽  
Breath Measurement ◽  
13Co2 Enrichment

Abstract.A new method was developed for continuous isotopic estimation of human whole body CO2 rate of appearance (Ra) during non-steady state exercise. The technique consisted of a breath-by-breath measurement of 13CO2 enrichment (E) and a real-time fuzzy logic feedback system which controlled NaH13CO3 infusion rate to achieve an isotopic steady state. Ra was estimated from the isotope infusion rate and body 13CO2 enrichment which was equal to E at the isotopic steady state. During a non-steady state incremental cycle exercise (5 w/min or 10 w/min), NaH13CO3 infusion rate was successfully increased by the action of feedback controller so as to keep E constant.

Digestibility of nutrients and milk productivity of cows when using the concentrate mixture with the inclusion of rapeseed presscake

2020 ◽  
pp. 48-53
Author(s):  
L. Yarmots ◽  
G. Yarmots ◽  
A. Belenkaya
Keyword(s):  
Protein Digestibility ◽  
High Energy ◽  
Negative Influence ◽  
The Body ◽  
Milk Productivity ◽  
Lactating Cows ◽  
Low Protein ◽  
Concentrate Mixture ◽  
Almost All ◽  
Experimental Group

For ruminants, especially high-yielding animals in addition to the complete supply of animals with protein, its digestibility in the rumen is important. With low protein digestibility in the rumen, the released ammonia will be more effectively used by the rumen microflora, and the undigestible protein in the subsequent sections of the digestive tract can serve as a source of amino acids for the body. The use of concentrate mixtures with the inclusion of local, affordable and cheaper grain feeds, in particular a high-energy and protein ingredient- rapeseed presscake makes it possible to increase the milk productivity of cows throughout lactation. These presscakes are well balanced in their amino acid composition and belong to feeds whose protein has a low degree of digestibility in the rumen. The purpose of the researches was to study the digestibility of nutrients and milk productivity of cows when using the concentrate mixture with the inclusion of rapeseed presscake. In the scientific and economic experiment has been carried out on lactating cows, where the cows of the experimental group in the concentrate mixture of peas has been replaced with rapeseed presscake the digestibility of nutrients in the ration, energy metabolism and milk productivity have been studied. Studies have shown that almost all the nutrients were significantly better digested by the animals of the experimental group. Energy in milk was more allocated by cows of the experimental group by 6,29 MJ. From cows of the experimental group for 100 and 305 days of lactation has been obtained more milk by 6,27 and 7,06 %, respectively, than from control herdmates. The biochemical parameters of blood were within the limits of the physiological norm in animals of both groups. Thus, the replacement of peas with rapeseed presscake in the concentrate mixture did not have a negative influence on the metabolic processes and helped to increase the milk productivity of cows.

Blood, joy and tears: menarche narratives of undergraduate females in a selected in Nigeria Private University

2017 ◽  
Vol 31 (4) ◽  
Author(s):  
Adenike Adegbayi
Keyword(s):  
Adolescent Health ◽  
Qualitative Methodology ◽  
Private University ◽  
The Body ◽  
Female Adolescent ◽  
Menstrual Period ◽  
Future Health ◽  
Female Relative ◽  
Undergraduate Females ◽  
Almost All

Abstract The aim of the study is to add to the body of knowledge on less researched aspects of female adolescent health in Nigeria. It specifically explored the menarche or first period narratives of 136 young women, focusing on the contents of the discussion that ensued with whom they told when they first got their period using qualitative methodology. It also explores sources of premenstrual information and how the menstrual period is managed. The sample consisted of 136 undergraduate females in Redeemer’s University, Ede, Nigeria. Almost all of the respondents (95%) received information about menstruation from mothers, female relatives and school lessons prior to menarche. The majority of the respondents first told either their mother or a female relative when they first got their period and viewed menarche as a crisis. Two salient themes emerged from the contents of the narratives; celebration and advice. The advice theme was further explored and three advice patterns were identified: being a woman, hygiene and changed dynamics in relationships with males. Data from the present study suggests that only certain aspects of the menstruation discourse have evolved. All respondents reported using sanitary towels during their menstrual period with the majority experiencing cramps regularly and (61%) using pharmalogical agents for remedy. It is envisaged that findings from the study will be useful in future health intervention programmes and research on female adolescent health in Nigeria and elsewhere.

Demonstration of the relationship between MSD and online learning during the COVID-19 pandemic

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Kochu Therisa Karingada ◽  
Michael Sony
Keyword(s):  
Online Learning ◽  
Undergraduate Students ◽  
Online Survey ◽  
Cross Sectional Study ◽  
The Body ◽  
Body Parts ◽  
Cross Sectional ◽  
Content Type ◽  
The Right ◽  
Almost All

PurposeThe COVID-19 pandemic lockdown has caught many educational institutions by surprise and warranted an abrupt migration from offline to online learning. This has resulted in an education change, without any time for due consideration, as regards its impact on musculoskeletal disorders (MSD) on students. The purpose of this study is to investigate MSD related to online learning during the COVID-19 pandemic lockdown.Design/methodology/approachA cross-sectional study was conducted on undergraduate students in India. In total, 261 students participated in this online survey.FindingsThe study finds that around 80% of students have reported some symptom in the head, neck and eyes since they started online learning. In total, 58% have reported MSD symptom in the right shoulder and 56% in the right hand fingers. Besides, more than 40 % of students experienced some MSD symptoms, in almost all the body parts studied, due to online learning. Correlation analysis is conducted between time spent on online learning per day and MSD symptoms.Originality/valueThis is the first study conducted on MSD and online learning during COVID-19 pandemic.

On the Regulation of the Respiration in Reptiles

1961 ◽  
Vol 38 (2) ◽  
pp. 301-314 ◽  
Author(s):  
BODIL NIELSEN
Keyword(s):  
Steady State ◽  
Body Temperature ◽  
Metabolic Rate ◽  
Temperature Interval ◽  
Normal Values ◽  
Pulmonary Ventilation ◽  
The Body ◽  
Respiratory Frequency ◽  
Temperature Changes ◽  
Instantaneous Increase

1. In two species of Lacerta (L. viridis and L. sicula) the effects on respiration of body temperature (changes in metabolic rate) and of CO2 added to the inspired air were studied. 2. Pulmonary ventilation increases when body temperature increases. The increase is brought about by an increase in respiratory frequency. No relationship is found between respiratory depth and temperature. 3. The rise in ventilation is provoked by the needs of metabolism and is not established for temperature regulating purposes (in the temperature interval 10°-35°C). 4. The ventilation per litre O2 consumed has a high numerical value (about 75, compared to about 20 in man). It varies with the body temperature and demonstrates that the inspired air is better utilized at the higher temperatures. 5. Pulmonary ventilation increases with increasing CO2 percentages in the inspired air between o and 3%. At further increases in the CO2 percentage (3-13.5%) it decreases again. 6. At each CO2 percentage the pulmonary ventilation reaches a steady state after some time (10-60 min.) and is then unchanged over prolonged periods (1 hr.). 7. The respiratory frequency in the steady state decreases with increasing CO2 percentages. The respiratory depth in the steady state increases with increasing CO2 percentages. This effect of CO2 breathing is not influenced by a change in body temperature from 20° to 30°C. 8. Respiration is periodically inhibited by CO2 percentages above 4%. This inhibition, causing a Cheyne-Stokes-like respiration, ceases after a certain time, proportional to the CO2 percentage (1 hr. at 8-13% CO2), and respiration becomes regular (steady state). Shift to room air breathing causes an instantaneous increase in frequency to well above the normal value followed by a gradual decrease to normal values. 9. The nature of the CO2 effect on respiratory frequency and respiratory depth is discussed, considering both chemoreceptor and humoral mechanisms.

Removal of Vancomycin during Plasmapheresis

1997 ◽  
Vol 31 (10) ◽  
pp. 1132-1136 ◽  
Author(s):  
Syble D McClellan ◽  
Charles H Whitaker ◽  
Richard C Friedberg
Keyword(s):  
Tertiary Care ◽  
Compartment Model ◽  
The Body ◽  
Patient Specific ◽  
Pharmacokinetic Parameters ◽  
Serum Concentrations ◽  
Total Clearance ◽  
Concentration Data ◽  
Vancomycin Concentration ◽  
Total Body

OBJECTIVE: To examine the removal of vancomycin during plasmapheresis, determine whether drug administration should be withheld prior to or a supplemental dose given after the procedure, and determine whether a redistribution phenomenon in vancomycin serum concentrations occurs after plasmapheresis. DESIGN: Prospective, cohort study. SETTING: An 800-bed, tertiary-care, teaching hospital. PATIENTS: Twelve patients receiving vancomycin as prescribed who were also undergoing therapeutic plasmapheresis. METHODS: Blood samples for determination of vancomycin concentrations were obtained from each patient immediately before, during, immediately after, and 2 hours after plasmapheresis. Vancomycin concentration in plasma removed by plasmapheresis and volume of plasma removed were measured. Patient-specific pharmacokinetic parameters were determined for each patient using serum concentration data and a one-compartment model. Percent of drug removed by plasmapheresis and percent increase in vancomycin total clearance secondary to plasmapheresis were calculated. RESULTS: A mean of 6.3% of the total body store of vancomycin was removed by plasmapheresis. Vancomycin clearance during plasmapheresis averaged 1.6 L/h, which was an average increase of 285% in the total clearance of vancomycin from the body. Nine of 10 patients had a higher observed vancomycin concentration 2 hours after plasmapheresis than that predicted by degrading the concentration observed immediately after the procedure, suggesting that redistribution in serum concentrations occurs after the procedure. CONCLUSIONS: A single one-volume plasmapheresis does not remove a clinically important amount of vancomycin; therefore, supplemental dosing after the procedure is not necessary. A redistribution phenomenon in vancomycin concentrations appears to exist after plasmapheresis. Further study is needed to determine how long the redistribution phase lasts and when vancomycin concentrations should be measured after plasmapheresis.

scholarly journals Total body irradiation induced mouse small intestine senescence as a late effect

2019 ◽  
Vol 60 (4) ◽  
pp. 442-450 ◽  
Author(s):  
Yu Zhao ◽  
Junling Zhang ◽  
Xiaodan Han ◽  
Saijun Fan
Keyword(s):  
Small Intestine ◽  
Total Body Irradiation ◽  
Profile Analysis ◽  
Bacterial Flora ◽  
Body Weight Loss ◽  
Underlying Mechanism ◽  
The Body ◽  
Mouse Small Intestine ◽  
Total Body ◽  
Almost All

Abstract Radiation can induce senescence in many organs and tissues; however, it is still unclear how radiation stimulates senescence in mouse small intestine. In this study, we use the bone marrow transplantation mouse model to explore the late effects of total body irradiation on small intestine. Our results showed that almost all of the body hairs of the irradiated mice were white (which is an indication of aging) 10 months after the exposure to radiation. Furthermore, compared with the age-matched control mice, there were more SA-β-galactosidase (SA-β-gal)–positive cells and an upregulation of p16 and p21 in 8 Gy–irradiated mice intestinal crypts, indicating that radiation induced senescence in the small intestine. Intestinal bacterial flora profile analysis showed that the diversity of the intestinal bacterial flora decreased in irradiated mice; in addition it showed that the principal components of the irradiated and control mice differed: there was increased abundance of Bacteroidia and a decreased abundance of Clostridia in irradiated mice. To explore the underlying mechanism, an RNA-sequence was executed; the results suggested that pancreatic secretion, and the digestion and absorption of proteins, carbohydrates, fats and vitamins were damaged in irradiated mice, which may be responsible for the body weight loss observed in irradiated mice. In summary, our study suggested that total body irradiation may induce senescence in the small intestine and damage the health status of the irradiated mice.

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