The Role of Calcium in the Isolation of Brush Borders from Epithelial Cells of Rat Small Intestine

1966 ◽  
Vol 1 (4) ◽  
pp. 415-424
Author(s):  
P. F. MILLINGTON ◽  
D. R. CRITCHLEY ◽  
P.W. A. TOVELL
Keyword(s):  
Small Intestine ◽  
Calcium Ions ◽  
Chelating Agent ◽  
Tris Buffer ◽  
Good Separation ◽  
The Third ◽  
Low Concentrations ◽  
Brush Borders ◽  
The Stability

A chelating agent such as EDTA or EGTA used with a dilute TRIS buffer at pH 7.2-7.5 was used in order to effect a good separation of brush borders from the epithelium of the small intestine. A good separation was not obtained in low concentrations of TRIS buffer or saline alone. Brush borders were not obtained when the calcium-chelate complex of EDTA or EGTA was used, and only a partial fractionation was obtained when the magnesium complex of EDTA was tried. The involvement of calcium was further illustrated by adding calcium salts directly to the fractionation medium; separation was prevented when sufficient calcium had been added to saturate the chelating agent. It was found that there was no precise optimum concentration for EDTA but a separation could not be obtained below 2.4 mM/1. The effect of changing the pH of the buffer was also investigated and it was demonstrated that the onset of the ability to release brush borders coincided approximately with the ionization of the third acid radical of the chelating agent. This is in keeping with the suggested hypothesis that EDTA acts by chelating calcium ions. From these and electron-microscope studies it is suggested that the binding of calcium ions is an important factor in the maintenance of the stability of the epithelial cell membrane.

The role of metabolites in the interspecific interaction of bacteria (review)

2021 ◽  
pp. 26-33
Author(s):  
Irina O. Yunusova ◽  
Anatoly A. Yakovlev
Keyword(s):  
Antimicrobial Properties ◽  
Interspecific Interaction ◽  
Antimicrobial Substances ◽  
Current Period ◽  
Initial Stage ◽  
Low Concentrations ◽  
Metabolic Products ◽  
Number Of Publications ◽  
The Stability

In the current period, scientists both in our country and abroad are actively studying the processes of interaction between microorganisms since an understanding of the mechanisms of communication and competition between them will contribute to the development of new strategies in the fight against infectious diseases. Nevertheless, although in recent years there has been a significant increase in the number of publications on the indicated problem, studies covering far from all possible variants of interactions between various microorganisms, are still at their initial stage, and are still less focused on the understanding of direct mechanisms of interaction. Of particular interest is the study of antagonistic relationships in which the development of some forms of microbes is inhibited by others through the antimicrobial substances they produce. Metabolites that display antimicrobial properties at low concentrations are one such substance. In the present work, the authors present a literature analysis indicating that between-population relationships, realized through metabolic products, are among the main factors that are aimed at the stability of microbial communities and management of their productivity and species composition, including mixed biofilms.

EFFECT OF THYROIDECTOMY ON THE ACTIVITY OF α-GLUCOSIDASES AND ACID HYDROLASES IN THE SMALL INTESTINE OF RATS DURING WEANING

1975 ◽  
Vol 66 (1) ◽  
pp. 31-36 ◽  
Author(s):  
OTAKAR KOLDOVSKÝ ◽  
JOCELYN JUMAWAN ◽  
MICHAEL PALMIERI
Keyword(s):  
Body Weight ◽  
Small Intestine ◽  
Acid Hydrolases ◽  
Enzyme Profile ◽  
The Third ◽  
Maltase Activity ◽  
Old Rats

SUMMARY Adrenalectomy performed on 14-day-old rats delayed the usual increase of sucrase and maltase activity as well as the decrease of acid β-galactosidase, β-glucuronidase and N-acetyl-β-glucosaminidase activity during the third postnatal week. Since these changes were only delayed, the role of the thyroid was explored. Thyroidectomy performed simultaneously with adrenalectomy on 14-day-old rats did not influence the increase in body weight and growth of the small intestine (already slowed down by adrenalectomy), but caused a further substantial delay in the maturation of the enzyme profile of the small intestine. Our results indicate that the thyroid is involved in regulation of the hydrolases studied.

The role of magnesium ion in the adenine phosphoribosyltransferase reaction

1970 ◽  
Vol 48 (3) ◽  
pp. 302-307 ◽  
Author(s):  
R. E. A. Gadd ◽  
J. Frank Henderson
Keyword(s):  
Stability Constant ◽  
Initial Velocity ◽  
Adenosine Monophosphate ◽  
Magnesium Ion ◽  
Adenine Phosphoribosyltransferase ◽  
Good Correspondence ◽  
Low Concentrations ◽  
High Concentrations ◽  
The Stability

Low concentrations of magnesium ion stimulate, and high concentrations inhibit, the adenine phosphoribosyltransferase reaction. The stability constant of the Mg–pyrophosphoryl moiety of phosphoribosylpyrophosphate was assumed to be the same as that of Mg–adenosine triphosphate; the stability constant of the Mg–phosphoryl moiety of phosphoribosylpyrophosphate was assumed to be the same as that of Mg–adenosine monophosphate, and the concentration of the monomagnesium complex of phosphoribosylpyrophosphate was calculated as a function of magnesium ion and phosphoribosylpyrophosphate concentrations. The good correspondence between these curves and those of initial velocity under the same conditions suggest that the monomagnesium complex of phosphoribosylpyrophosphate is the true substrate of this reaction.

scholarly journals A fluorimetric study of the role of calcium ions in the stability of thermolysin

1977 ◽  
Vol 165 (3) ◽  
pp. 539-545 ◽  
Author(s):  
Angelo Fontana ◽  
Claudio Vita ◽  
Enrico Boccu' ◽  
Francesco M. Veronese
Keyword(s):  
Calcium Ions ◽  
Fluorescence Emission ◽  
Protein Molecule ◽  
Fluorescence Emission Spectrum ◽  
Guanidinium Chloride ◽  
Emission Maximum ◽  
Heat Stable ◽  
Tryptophan Residues ◽  
The Stability

1. Fluorimetric techniques were used to characterize the environment of tryptophan residues in thermolysin and apo-thermolysin. The apo-thermolysin was obtained by dissolving the enzyme in the presence of 10mm-EDTA, which removed the functional Zn2+ ion and the four Ca2+ ions/molecule from the enzyme. 2. At 25°C in aqueous solution the fluorescence-emission spectrum of the native holoenzyme, on excitation at 290nm, was essentially characteristic of tryptophan, with an emission maximum at 333nm. The emission maximum of the apoenzyme is red-shifted to 338nm and the relative intensity of fluorescence is decreased by 10%, both effects indicating some unfolding of the protein molecule, with the indole groups being transferred to a more hydrophilic environment. 3. Fluorescence quenching studies using KI, N′-methylnicotinamide hydrochloride and acrylamide indicated a more open structure in the apoenzyme, with the tryptophan residues located in a negatively charged environment. 4. The thermal properties of the apoenzyme, as monitored by fluorescence-emission measurements, are dramatically changed with respect to the native holoenzyme. In fact, whereas the native enzyme is heat-stable up to about 80°C, for the apoenzyme a thermal transition is observed near 48°C. The apoenzyme is also unstable to the action of unfolding agents such as urea and guanidinium chloride, much as for other globular proteins from mesophilic organisms. 5. The functional Zn2+ ion does not contribute noticeably to the stability of thermolysin. 6. It is concluded that a major role in the structural stability of thermolysin is played by the Ca2+ ions, which have a bridging function within this disulphide-free protein molecule.

scholarly journals Role of an additional third screw in the fixation of transverse patellar fracture with two parallel cannulated screw and anterior wire

2020 ◽  
Vol 21 (1) ◽  
Author(s):  
Chih-Wei Chang ◽  
Chih-Hsien Chen ◽  
Chun-Ting Li ◽  
Yen-Nien Chen ◽  
Tai-Hua Yang ◽  
...  
Keyword(s):  
Knee Flexion ◽  
Cannulated Screw ◽  
Cannulated Screws ◽  
Full Extension ◽  
The Third ◽  
Gap Opening ◽  
Biomechanical Effect ◽  
The Stability ◽  
Patellar Fractures

Abstract Background Two parallel cannulated screws along with an anterior wire to construct a tension band is a popular approach in transverse patellar fractures. However, the optimal screw proximity, either deep or superficial screw placements, remains controversial. Hence, a new concept of the addition of a third screw to form a triangular configuration along with the original two parallel screws was proposed in this study. Therefore, the biomechanical effect of the additional third screw on the stability of the fractured patella was investigated with finite element (FE) simulation. Methods An FE knee model including the distal femur, proximal tibia, and fractured patella (type AT/OTA 34-C) was developed in this study. Four different screw configurations, including two parallel cannulated screws with superficial (5-mm proximity) and deep (10-mm proximity) placements and two parallel superficial screws plus a third deep screw, and two parallel deep screws plus a third superficial screw, with or without the anterior wire, were considered for the simulation. Results Results indicated that the addition of a third screw increased stability by reducing the dorsal gap opening when two parallel screws were deeply placed, particularly on the fractured patella without an anterior wire. However, the third screw was of little value when two parallel screws were superficially placed. In the existence of two deep parallel screws and the anterior wire, the third screw reduced the gap opening by 23.5% (from 1.15 mm to 0.88 mm) and 53.6% (from 1.21 mm to 0.61 mm) in knee flexion 45° and full extension, respectively. Furthermore, in the absence of the anterior wire, the third screw reduced the gap opening by 73.5% (from 2 mm to 0.53 mm) and 72.2% (from 1.33 mm to 0.37 mm) in knee flexion 45° and full extension, respectively. Conclusion Based on the results, a third cannulated screw superficially placed (5-mm proximity) is recommended to increase stability and maintain contact of the fractured patella, fixed with two parallel cannulated screws deeply placed (10-mm proximity), particularly when an anterior wire was not used. Furthermore, the third screw deeply placed is not recommended in a fractured patella with two parallel superficial screws.

scholarly journals Composition and stability of complexes of Ephedrine hydrochloride with Ni2+, Zn2+, and Cd2+ as toxic ions

2003 ◽  
Vol 71 (2) ◽  
pp. 75-88
Author(s):  
Nabawia EL Guindi
Keyword(s):  
Metal Ions ◽  
Chelating Agent ◽  
Cadmium Ions ◽  
Nickel Zinc ◽  
Ephedrine Hydrochloride ◽  
Stability Of Complexes ◽  
Different Temperatures ◽  
The Stability

The complexes of Ephedrine with Nickel, Zinc and Cadmium ions have been investigated spectrophotometricalfy using the method of corresponding solutions [I-3] and pH-metrically using Irving and Rossoti technique [4] Two compositions were observed spectrophotometrically 1 : 1 and 2: 1 (L: M) for concentration of metal ions (0.5 x 10-3 M and 1 x 10-3 M) hile the first composition only predominate at concentration of metal ions (1.5 x 10-3 M and 2 x 10-3 M ). The stability of complexes show that complexes of Ni2+ are more stable than that of Zn2+ an Cd2+, Moreover, the composition and stabilities of complexes were studied pHmetrically in aqueous medium at 0.1 M NaCl and two different temperatures 30°C and 40°C; hence the value of the free energy change (ΔG°), the enthalpy (ΔH°) and the entropy (ΔS°) were calculated at 30°C. Beside the role of Ephedrine as chelating agent to toxic elements, the complexometric method was used for the determination of Ephedrine in its pure form and in tablets.

scholarly journals The role of calcium ions in the stability and instability of a thermolysin-like protease

2011 ◽  
Vol 20 (8) ◽  
pp. 1346-1355 ◽  
Author(s):  
V. G. H. Eijsink ◽  
B. W. Matthews ◽  
G. Vriend
Keyword(s):  
Calcium Ions ◽  
Stability And Instability ◽  
The Stability

Mitochondrial matrix calcium ions regulate energy production in myocardium: A cytochemical study

1990 ◽  
Vol 48 (2) ◽  
pp. 166-167
Author(s):  
W.A. Jacob ◽  
R. Hertsens ◽  
A. Van Bogaert ◽  
M. De Smet
Keyword(s):  
Energy Metabolism ◽  
Calcium Ions ◽  
Energy Production ◽  
Regulation Of Respiration ◽  
Free Calcium ◽  
Mitochondrial Matrix ◽  
Cytochemical Study ◽  
Nmr Techniques

In the past most studies of the control of energy metabolism focus on the role of the phosphorylation potential ATP/ADP.Pi on the regulation of respiration. Studies using NMR techniques have demonstrated that the concentrations of these compounds for oxidation phosphorylation do not change appreciably throughout the cardiac cycle and during increases in cardiac work. Hence regulation of energy production by calcium ions, present in the mitochondrial matrix, has been the object of a number of recent studies.Three exclusively intramitochondnal dehydrogenases are key enzymes for the regulation of oxidative metabolism. They are activated by calcium ions in the low micromolar range. Since, however, earlier estimates of the intramitochondnal calcium, based on equilibrium thermodynamic considerations, were in the millimolar range, a physiological correlation was not evident. The introduction of calcium-sensitive probes fura-2 and indo-1 made monitoring of free calcium during changing energy metabolism possible. These studies were performed on isolated mitochondria and extrapolation to the in vivo situation is more or less speculative.

Kinetics of Various 99mTc-Sn-Pyrophosphate Compounds in the Rat

1977 ◽  
Vol 16 (04) ◽  
pp. 157-162 ◽  
Author(s):  
C. Schümichen ◽  
B. Mackenbrock ◽  
G. Hoffmann
Keyword(s):  
Normal Saline ◽  
Half Life ◽  
Compound A ◽  
Short Half Life ◽  
Low Concentrations ◽  
The Stability ◽  
Kinetics Of ◽  
In Vitro Stability

SummaryThe bone-seeking 99mTc-Sn-pyrophosphate compound (compound A) was diluted both in vitro and in vivo and proved to be unstable both in vitro and in vivo. However, stability was much better in vivo than in vitro and thus the in vitro stability of compound A after dilution in various mediums could be followed up by a consecutive evaluation of the in vivo distribution in the rat. After dilution in neutral normal saline compound A is metastable and after a short half-life it is transformed into the other 99mTc-Sn-pyrophosphate compound A is metastable and after a short half-life in bone but in the kidneys. After dilution in normal saline of low pH and in buffering solutions the stability of compound A is increased. In human plasma compound A is relatively stable but not in plasma water. When compound B is formed in a buffering solution, uptake in the kidneys and excretion in urine is lowered and blood concentration increased.It is assumed that the association of protons to compound A will increase its stability at low concentrations while that to compound B will lead to a strong protein bond in plasma. It is concluded that compound A will not be stable in vivo because of a lack of stability in the extravascular space, and that the protein bond in plasma will be a measure of its in vivo stability.

Testosterone Potentiation of Ionophore and ADP Induced Platelet Aggregation : Relationship to Arachidonic Acid Metabolism

1981 ◽  
Vol 46 (02) ◽  
pp. 538-542 ◽  
Author(s):  
R Pilo ◽  
D Aharony ◽  
A Raz
Keyword(s):  
Arachidonic Acid ◽  
Platelet Aggregation ◽  
Unsaturated Fatty Acids ◽  
Human Platelet ◽  
Platelet Rich Plasma ◽  
Arachidonic Acid Metabolism ◽  
Ionophore A23187 ◽  
Low Concentrations ◽  
Induced Aggregation

SummaryThe role of arachidonic acid oxygenated products in human platelet aggregation induced by the ionophore A23187 was investigated. The ionophore produced an increased release of both saturated and unsaturated fatty acids and a concomitant increased formation of TxA2 and other arachidonate products. TxA2 (and possibly other cyclo oxygenase products) appears to have a significant role in ionophore-induced aggregation only when low concentrations (<1 μM) of the ionophore are employed.Testosterone added to rat or human platelet-rich plasma (PRP) was shown previously to potentiate platelet aggregation induced by ADP, adrenaline, collagen and arachidonic acid (1, 2). We show that testosterone also potentiates ionophore induced aggregation in washed platelets and in PRP. This potentiation was dose and time dependent and resulted from increased lipolysis and concomitant generation of TxA2 and other prostaglandin products. The testosterone potentiating effect was abolished by preincubation of the platelets with indomethacin.

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