Power-time Curves Research Articles

Stimulation Effect of Lithium on the Metabolic Activity of Liver Tissue Mitochondria Measured by Microcalorimetry

The effect of Li(I) on the metabolism of mitochondria isolated from Carassius auratus liver tissue was investigated by microcalorimetric method to provide evidence for mitochondria hypothesis of bipolar disorder (BPD) and to explore therapeutic mechanism of drug for treatment of BPD. Obvious stimulation induced by Li(I) on mitochondria metabolism was reflected by power-time (P-t) curves. The power-time curves of hepatic mitochondria metabolism without Li(I) could be divided into four parts: lag phase, active recovery phase, stationary phase, and decline phase. When Li(I) was added, the second heat peak occurred in a concentration-dependent sequence. Considering the first heat peak on the P-t curves, Li(I) in the range of therapeutic and lower concentration induced slight alterations in comparison with the characteristic heat peak observed in the control. However, Li(I) above the therapeutic concentration resulted in significant changes. Heat output increased with the concentration of Li(I), but the rate constant (k2) and the maximum heat power (Pmax2) for the second heat peak reached maximum value in the range of therapeutic concentration. Mechanism of activation of mitoKatp was suggested and discussed.

Inhibitory study of some novel Schiff base derivatives on Staphylococcus aureus by microcalorimetry

The effect of a series of novel Schiff base compounds on Staphylococcus aureus was studied by microcalorimetric method at 37 °C The results showed that all of the organic compounds had the capacity to inhibit the growth of S. aureus in different extent. And the extent and duration of the inhibitory effect on the growth of S. aureus, judged from the rate constant ( k), varied with the different structure of the Schiff base compounds. According to the power–time curves, the multiplication rate constant and inhibition ratio were calculated. The growth rate constant of S. aureus (in log phase) in the presence of Schiff base compounds decreased with the increasing of the concentrations of these compounds regularly. The experimental results revealed that the hydrophilicity of Schiff bases had a great influence on their antibacterial activity. Of these Schiff bases, the greater their hydrophilicity, the higher their antibacterial activity. The antibacterial structure–activity relationship (SAR) of Schiff base derivatives was also briefly discussed.

Microcalorimetry as a possible tool for phylogenetic studies of Tetrahymena

Using isothermal microcalorimetry, the growth power-time curves of three strains of Tetrahymena were determined at 28 degrees C. Their Euclidean distances and cluster analysis diagram were obtained by using two thermokinetic parameters (r and Q(log)), which showed that T. thermophila BF1 and T. thermophila BF5 had a closer relationship. Compared with the single molecular biomarker (ITS1) method, microcalorimetry wasmaybe a simpler, more sensitive andmore economic technique in the phylogenetic studies of Tetrahymena species.

Calorimetric investigation of the effect of hydroxyanthraquinones in Rheum officinale Baill on Staphylococcus aureus growth

The inhibitory effects of five hydroxyanthraquinones (HAQs) from root and rhizoma of Rheum officinale Baill, a traditional Chinese medicinal (TCM) herb, on Staphylococcus aureus growth were investigated by calorimetry. The power–time curves of S. aureus with and without HAQ were acquired and the extent and duration of inhibitory effects on the metabolism evaluated by growth rate constants ( k 1, k 2), half inhibitory ratio (IC 50), maximum heat output ( P max) and peak time ( t p). The value of k 1 and k 2 of S. aureus in the presence of the five HAQs decreased with the increasing concentrations of HAQs. Moreover, P max was reduced and the value of t p increased with increasing concentrations of the five drugs. The inhibitory activity varied for different drugs. IC 50 of the five HAQs was 4 μg ml −1 for emodin, 3.5 μg ml −1 for rhein, 10 μg ml −1 for aloe-emodin, 1000 μg ml −1 for chrysophanol, 1600 μg ml −1 for physcion. The sequence of antimicrobial activity of the five HAQs: rhein > emodin > aloe-emodin > chrysophanol > physicion.

Microcalorimetric study of <Emphasis Type=?Italic?>Bacillus thuringiensis</Emphasis> growth with different plasmid numbers and various promoters

A microcalorimetric technique was used to investigate the influence of plasmid copy number and various promoters on the green fluorescent protein expression in Bacillus thuringiensis. The power-time curves of the growth metabolism of B. thuringiensis have been determined by using an LKB-2277 bioactivity monitor at 28°C. For evaluation of the results, the maximum peak-heat output power ( P max ), the generation time ( t G ), the growth rate constants ( k ) in the log phase, the total heat effect ( Q total ) for the growth metabolism of Bacillus thuringiensis were determined. The results firstly indicated that the more plasmid copy number per cell the more protein synthesization, and promoter BtI-BtII had a stronger impact on the gene expression than promoter 3A investigated by the method of microcalorimetry.

Microcalorimetry is a sensitive method for studying the effect of nucleotide mutation on promoter activity

Microcalorimetric method was successfully used to study the effect of nucleotide mutations on promoter activity and identify the important nucleotide necessary for the promoter function in Escherichia coli. The thermokinetic parameters, such as k, I and IC 50, were calculated from the metabolic power–time curves obtained by microcalorimetric measurement using the TAM air Isothermal Microcalorimeter (manufactured by Thermometric AB company of Sweden). Analysis of these data revealed that different nucleotide mutations in −10 box sequence of RM07 fragment had different effect on the promoter activity. Our research also suggest that the microcalorimetric method is a very sensitive and easily performed method for investigation of promoter mutation.

The effect of zinc(II) on the growth of E . coli studied by microcalorimetry

By using an LKB2277 Bioactivity Monitor, stop-flow mode, the power-time curves of E . coli at 37°C effected by zinc(II) were determined. Some parameters, such as growth rate constants k, inhibitory ratio I, the maximum heat production rate P max heat output Q and the time in the maximum heat production t max were obtained. According these parameters, we found that a low concentration of zinc(II) had a promoting action on the growth of E. coli, but a high concentration of zinc(II) had an inhibitory action. The toxicity of zinc(II) can also be expressed as half inhibitory concentration IC 50 of zinc(II), i.e., 50% effective in this inhibition. The value of IC 50 of zinc(II) on E. coliis 28.09 µg mL-1. The assay is quantitative, inexpensive and versatile.

Characterization of sulfate-reducing bacteria in yeast industry waste by microcalorimetry and PCR amplification

Sulfate-reducing bacteria (SRB) were isolated from anaerobic sludge of yeast factory wastewater treatment plant by cultivation on Postgate C medium. Microcalorimetry was used to monitor the anaerobic digestion processes and to measure the growth rates of sulfate-reducing bacteria. The maximum growth rates determined by microcalorimetry and ATP analysis were different— μ max(d Q/d t) = 0.165 ± 0.008 h −1 and μ max(N ATP) = 0.207 ± 0.013 h −1. Experiments on the cultivation of SRB from yeast industry wastewater treatment plant in batch culture showed that during the first 20 h the concentration of sulfate decreased from 78.3 mM down to 62.2 mM while the increase of sulfide production was negligible. Perceptible amount of sulfide (7.82 mM) appeared on the 33.5 h of fermentation together with a peak on the power–time curve and considerable increase in the cell count (1.26 × 10 9). First steps of sulfate metabolism (activation of sulfate by ATP sulfurylase, production of H 2) are accompanied by endothermic heat effects, therefore the values of thermal power remain moderate until the evolution of sulfide starts. The influence of green microalgae Chlorococcum sp. (preparation Biotreat 100) on the growth characteristics of microorganisms was also studied. Identification of one SRB strain was started by sequencing of PCR-amplified 16S rRNA gene. Two sets of primers were used for PCR amplification, both specific for domain Bacteria but giving different gene fragments. PCR-products were purified with JETQUICK kit according to the manufacturer instructions.

Microbiological and calorimetric investigations on the antimicrobial actions of different propolis extracts: an in vitro approach

The antibacterial action of three different types of propolis extracts: (i) water-extracted propolis (WEP), (ii) propolis volatiles (PV), and (iii) ethanol-extracted propolis (EEP) were investigated by flow microcalorimetry coupled with polarography, and by Petri dish bioassay methods. The water-extracted propolis solution had the weakest antibacterial and antifungal action, compared to the other two extracts, which showed effects nearly similar to each other. Filamentous fungi were generally less sensitive to propolis than bacteria and yeasts, regardless of the type or concentration of propolis. Propolis displayed both bacteriostatic and bactericidal actions depending on the concentration, type of propolis, and type of bacteria tested. The Gram negative bacterium E. coli was insensitive to most treatments, and higher concentrations of propolis were required to achieve bactericidal effects. Treatments of bacteria with weak propolis concentrations caused a decrease in the calorimetric power-time ( p– t) curves to lower levels, at which the curves remained for the rest of the experimental period, decreased to the baseline with the course of time, or revived after some time and attained peaks. The treatment with strong concentrations, however, caused the curves to descend to the baseline immediately.

Correlations Between Systemic Work and Summed Measures of Lower Extremity Mechanical Demand

0720 Integrated measures, such as net joint moment impulse and mechanical energy expenditure, may be more appropriate than peak measures when quantifying lower extremity demand. Currently, it is not known which of these measures may be more appropriate when analyzing dynamic exercise. PURPORSE: To determine the relations between the work performed at the center of mass (WCOM) and the summed measures of mechanical output at the hip, knee, and ankle. METHODS: Older adult participants (N = 20) performed a forward step-up under three loading conditions (no external resistance, and external resistances equal to 5% and 10% of the participants' body weight) for a total of 60 data sets. Support moment impulse (SMI) was calculated as the algebraic sum of the integrals of the moment-time curves at the hip, knee, and ankle. Total mechanical energy expenditure (MEE) was calculated as the algebraic sum of the integrals of the absolute power-time curves at the hip, knee, and ankle. Associations were determined for both concentric and eccentric phases of the movement using Pearson's Product moment correlation coefficient (á = 0.05). RESULTS: Results are presented in Table 1. Both measures were correlated with WCOM during both phases at the 0.01 level. A stronger association was seen between WCOM and MEE than with WCOM and SMI: 79%–80% of the variability in WCOM was accounted for by MEE, while 51%–64% of the variability in WCOM was accounted for by SMI. Additionally, MEE appeared to be less affected by movement phase and had a lower coefficient of variation.Table 1: Correlation coefficients (r), common variance (R2), and coefficients of variation (CV).CONCLUSION: Results suggest total mechanical energy expenditure may be a more appropriate measure of mechanical demand during this dynamic activity. Similar analyses should be conducted for different types of exercises (i.e., exercises with a large isometric component). Supported by NIA AG19320-01.

Solution calorimetry as a tool for investigating drug interaction with intestinal fluid

Solution calorimetry offers a reproducible technique for measuring the enthalpy of solution (Δ sol H) of a solute dissolving into a solvent. The Δ sol H of two solutes, propranolol HCl and mannitol were determined in simulated intestinal fluid (SIF) solutions designed to model the fed and fasted states within the gut, and in Hanks’ balanced salt solution (HBSS) of varying pH. The bile salt and lipid within the SIF solutions formed mixed micelles. Both solutes exhibited endothermic reactions in all solvents. The Δ sol H for propranolol HCl in the SIF solutions differed from those in the HBSS and was lower in the fed state than the fasted state SIF solution, revealing an interaction between propranolol and the micellar phase in both SIF solutions. In contrast, for mannitol the Δ sol H was constant in all solutions indicating minimal interaction between mannitol and the micellar phases of the SIF solutions. In this study, solution calorimetry proved to be a simple method for measuring the enthalpy associated with the dissolution of model drugs in complex biological media such as SIF solutions. In addition, the derived power–time curves allowed the time taken for the powdered solutes to form solutions to be estimated.

A study of promotive and fungistatic actions of steroidal saponin by microcalorimetric method

In this paper, the steroidal saponin was isolated from natural Chinese drugs of yam and allum macrostemon bunge. The promotive and fungistatic actions of steroidal saponin was studied. The power–time curves of growth of Escherichia coli at different concentrations of steroidal saponin were determined by using a 2277 Thermal Activity Monitor. The rate constant of promotive and fungistatic actions was calculated. The relationship between growth rate constant with concentration was established. The optimum concentration of promotive action and the minimum concentration of fungistatic action were determined. Results have proved that the steroidal saponin of yam and allum macrostemon bunge has promotive action (in low concentration) and fungistatic action (in high concentration).

Examination of the growth of probiotic culture combinations by the isoperibolic batch calorimetry

Probiotic (“intestinal friend”) foods, and probiotic dairy products in particular, have substantially increased in number recently. In the production of some of these products a problem is caused by the fact that the thermotolerant microbes that produce the probiotic effect do not generate an aroma; the taste of the product is given by aroma-producing mesophilic microbes. The growth optima of the two microbe groups do not coincide. Given that heat is released in the course of microbe reproduction, the isoperibolic calorimetry method appears the best and fastest for monitoring the process. During the experiments the thermotolerant Prebiolact, owned by the Hungarian Dairy Research Institute (HDRI) and clinically verified to be probiotic, and Hansen Company’s CHN-22 mesophilic butter culture were examined bred separately and together. The cultures were incubated at 30 °C, at which temperature prior studies had shown both lactic acid bacteria cultures were capable of growing. The cultures were injected into milk, then the microbe growth heat flow-time curve over 18 h was taken on the Setaram Micro DSC-II calorimeter at 30 °C under isothermic conditions. Analysis of the heat flow curves led to the following conclusions. Both lactic acid bacteria cultures grow well at the non-optimal temperature of 30 °C, thermotolerant Prebiolact somewhat faster and mesophilic CHN-22 slower. The two cultures do not impede each other in mixed cultures; the growth peaks of the two cultures were easily isolated on the power–time curve by a deconvolution program. In sum it can be stated that mixed cultures of the two cultures examined can be used to produce dairy products which are probiotic, but their taste character (e.g. aroma) is determined by the butter culture. To date we have elaborated production procedures for probiotic butter cream and heat-resistant sour cream using the two cultures in a mixed one.

Study of Activation and Inhibition of Certain Metal Ions to Amylase Catalyzed Reaction by Microcalorimetry

AbstractWith or without activation or inhibition of metal ion, the power‐time curves of amylase catalyzed reaction were determined by a 2277 thermal activity monitor (Sweden). The Michaelis constant (K), apparent Michaelis constant (Km), maximum velocity (vm) and apparent maximum velocity (vam) of amylase catalyzed reaction were obtained using thermokinetic theory and reduced extent method.On the basis of data obtained, the following relationships between Km and concentration of metal ion (c) were establishedfor inhibitor of Ni2+Km = 2.9648 × 10−3‐1.3912 × 10−4cR =0.9998for inhibitor of Co2+Km = 1.0227 × 10−3 + 8.2676 × 10−6cR = 0.9955for activator of Ca2+Km = 1.0630 × 10–7c2‐1.8311 × 10−6c + 9.3058 × 10−6R = 0.9999for activator of Li+Km = 5.6300 × 10–8c2‐1.5329 × 10−6c + 1.2662 × 10−5R = 0.9999The Km‐c relationships show a strenuous inhibitory effect for Ni2+ and a strenuous active effect for Ca2+.

Microcalorimetric study of the action of Yb3+ ion on the growth of Staphylococcus aureus

AbstractA microcalorimetric method was used to evaluate the action of Yb3+ ions on the growth metabolism of Staphylococcus aureus. The power‐time curves of the growth metabolism of Staphylococcus aureus and the action of Yb3+ ions were obtained by using stopped‐flow method at 37°C. For evaluation of the action, the growth rate constants (k1 and k2) for the log phase 1, log phase 2, and the total heat effect (Qtotal) for Staphylococcus aureus were determined. The results show that Yb3+ ions at low concentrations have the stimulatory effect on Staphylococcus aureus and that Yb* ions at higher concentration could inhibit its growth.

Study of the thermokinetic properties of copper(II) on Escherichia coli growth.

By using an LKB2277 Bioactivity Monitor, stop-flow mode, the power-time curves of Escherichia coli at 37 degrees C affected by Cu(II) were determined. Some parameters, such as growth rate constants k, inhibitory ratio I, the heat output Qlog in the log phase, and the generation times G were obtained. According to these parameters, we found that a low concentration of Cu(II) (0-20 microg/mL) had an promoting action on the growth of E. coli, but a high concentration of Cu(II) (40-100 microg/mL) had an inhibitory action. The toxicity of Cu(II) can also be expressed as the half-inhibitory concentration IC50; the value is 69.7 microg/mL. The assay is quantitative, inexpensive, and versatile.

Lower-limb extension power: How well does it predict short distance speed skating performance?

Purpose: This study was aimed to explore the relationship between lower limb extension power measured by isokinetic knee extensions (IK) and vertical jumps performed on a force plate (VJ) and speed skating (SS) sprint power measured by a laser device. Methods: Twenty elite short- and long-track speed skaters performed 100 m sprints followed by VJ and IK trials. Power-time curves were calculated off-line. Pearson correlation coefficients were used to determine the degree of association between the variables. Results: SS sprint power correlates strongly with VJ power (r = 0.870; p < 0.001) while IK power showed a weaker but significant correlation to both (r = 0.707 and r = 0.706, respectively; p < 0.01). As expected, SS times at 15 m and 100 m were inversely associated with SS sprint power (r = -0.818 and r = -0.909; p < 0.001) and VJ power (r = -0.730 and r = -0.763; p < 0.001), and to a lesser degree with IK power (r = -0.602; r = -0.618; p < 0.01). Conclusion: The analyses differentiate between methods of estimating power in speed skaters, and show a strong relationship between initial SS performance and muscular power. Given that 100 m split times strongly relate to final 500 m results (r = 0.972; p < 0.001, N = 332), it is reasonable to believe that an initial power and a stable peak speed before the first curve may lead to achieving the winning edge in short SS events. A finding of particular interest is that isokinetic power results are correlated significantly with the practical outcomes of the performance in spite of the high specificity of the isokinetic testing method.

Microcalorimetric Study of the Biological Effects of Zn2+ on Bacillus thuringiensis Growth

AbstractA microcalorimetric technique was used to investigate the influence of Zn2+ on the growth metabolism of Bacillus thuringiensis. LKB‐2277 Bioactivity Monitor was employed to obtain the power‐time curves, from which the maximum peak‐heat output power (Pmax) in the log phase, the growth rate constants (k), the inhibitory ratios (I), the generational time (tG) and the total heat effect (Qtotal) in 23 h for the growth metabolism of Bacillus thuringiensis at 28 °C can be evaluated. The results indicate that the concentration of Zn2+ affects its growth obviously. Low concentration (0–50 μg/mL) of Zn2+ promotes the growth of Bacillus thuringiensis while high concentration (50–500 μg/mL) of Zn2+ inhibits its growth. When the concentration reached up to 600 μg/mL, it can not grow at all.

The inhibitory biodegradation effects of the pesticide 2,4-D when chemically anchored on silica gel

The pesticide 2,4-D (2,4-dichlolorophenoxyacetic acid) was immobilized on a silica gel surface to yield a new compound designed SiD. The free and anchored pesticide was applied to typical Brazilian agricultural soils and the biodegradation caused by microbial activity was followed by microcalorimetry. The activity of the microorganisms on soil samples under 34.8% of controlled humidity at 298.15±0.02 K was determined through power–time curves. The recorded curves for increasing amounts of the 2,4-D active principle varied from zero to 6.67 mg per gram of soil. The increased amounts of both free and immobilized pesticide caused an enhancement of the original thermal effect. The calorimetric data demonstrated that the anchored pesticide (SiD) presents a much lower biodegradation with microbial activity, when compared with the free pesticide (2,4-D).

The influence of some physicochemical parameters on the microbial growth in soils

Microcalorimetric techniques have been used to study the influence of different physicochemical parameters on microbial growth in different soils in Galicia (NW Spain). The study was carried out using a 4 channels Thermal Activity Monitor (Thermometric, Sweden). Two types of soil, humic cambisol and umbric regosol, with different uses, vineyard, orchard, maize field, and scrubland, were investigated. Microbial activity in all the soils studied was stimulated by the addition of 1.25 mg of glucose g −1 soil. The power–time curves recorded from every experiment were analysed and from these analyses characteristic parameters such as peak time, peak height and microbial growth rate constants were determined. The influence of different environmental parameters, temperature (ambience and soil), moisture content (sample and residual), pH in water, and C/N ratio, were considered.