[Action of trioxyethylrutin on capillary resistance and venous disorders in pregnant women].
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Adult↗
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The direct separation of the diastereoisomers and enantiomers of the fungicide triadimenol by micellar electrokinetic capillary chromatography.
The direct chiral separation of the four enantiomers of the systemic fungicide triadimenol has been investigated using micellar electrokinetic capillary chromatography (MECC) with cyclodextrin (CD) chiral selectors and organic modifiers. The capillary operating temperature, applied voltage, and column diameter were all shown to be important factors in achieving an enantioselective separation. The addition of various CDs to the micellar buffer mixture was evaluated. The type of CD and its concentration affected the degree of separation, with the best separation of the enantiomers demonstrated for heptakis 2,6-di-O-methyl-beta-cyclodextrin (di-OMe-beta-CD). The addition of organic modifiers and CDs to the background electrolyte further enhanced separation. The best separation of the four enantiomers was obtained using an MECC buffer system consisting of 20% methanol, 0.02 M hydroxypropyl-beta-cyclodextrin (HO-Pr-beta-CD), and 0.05 M sodium dodecyl sulfate (SDS) in 0.02 M sodium borate and 0.02 M disodium hydrogen phosphate. The reported method demonstrates how the separation of enantiomers can be achieved by systematically varying the parameters in an MECC buffer system.
Capillary Action↗
Separation of polynuclear aromatic hydrocarbons by micellar electrokinetic capillary chromatography using sodium taurodeoxycholate modified with organic solvents.
The usefulness of a bile acid salt, sodium taurodeoxycholate (STDC), as a surfactant and organic solvents as organic modifiers for the separation of 16 polynuclear aromatic hydrocarbons (PAHs) on the U.S. EPA priority pollutant list by micellar electrokinetic capillary chromatography (MEKC) was investigated. The best resolution of analytes was obtained with a phosphate-borate buffer containing 50 mM STDC and 30% acetone. Short capillaries effected rapid (< 6 min) partial PAH separation, an approach that has potential use in screening studies. The capability of the developed separation system was demonstrated in the analysis of ambient air extracts.
Acetone↗
The endocrine control of blood volume, blood pressure and sodium balance: atrial hormone and renin system interactions.
The atrial peptide hormone exhibits remarkable vasorelaxant, natriuretic and hypovolaemic actions, suggesting that it is part of a cardiovascular control mechanism which operates to regulate blood pressure, blood volume and sodium balance. In this endocrine control, the renin axis provides the primary defence against sodium volume depletion and hypotension while atrial hormone plays an increasingly active counter-role for coping with situations that involve a sodium-volume surfeit or rising blood volume or blood pressure levels. For this assignment, the atrial hormone acts in four different ways to counter or oppose the renin-angiotensin-aldosterone axis. Thus, it promptly reduces renin secretion, it relaxes angiotensin-constricted vessels, it blocks angiotensin-induced aldosterone synthesis, and its natriuresis opposes aldosterone-induced sodium retention. Another special action of atrial hormone seems to be rapidly adjust central blood volumes by promoting the rapid transfer of fluid to the extracellular spaces. This hypovolaemic action probably reflects an action on capillary fluid exchange. It is reflected by a prompt and sustained rise in haematocrit levels. A similar action on the glomerular capillaries may be involved in causing natriuresis. These effects serve to rapidly decompress blood volumes and thereby reduce cardiac work. More work is needed to define the afferent stimuli to the right and left heart which elicit atrial hormone release. The possible role(s) of this new hormonal system in hypertensive and oedematous cardiovascular disorders also remains to be defined.
Angiotensin II↗
[Influence of the ovarian cycle on the behavior of capillary circulation and the modifying action of progesterone; demonstrable during surgery].
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Capillaries↗
Endothelins inhibit adenylate cyclase in brain capillary endothelial cells.
The action of endothelins (Et) on cAMP formation was studied in endothelial cells from rat brain microvessels. Et-1 and Et-3 had no action by themselves. They both inhibited cholera toxin stimulated adenylate cyclase by about 50%. K0.5 values were observed at 2 nM and 40 nM for Et-1 and Et-3 respectively, indicating an involvement of a low affinity Et-3 receptor. Coupling to adenylate cyclase was achieved by a pertussis toxin sensitive mechanism. Another action of endothelins in brain capillary endothelial cells was to stimulate phospholipase C. This action involved a low affinity Et-3 receptor and a pertussis toxin insensitive mechanism. It is concluded that in brain capillary endothelial cells, ETA like receptors are coupled to phospholipase C and to adenylate cyclase via two different mechanisms.
Adenylyl Cyclase Inhibitors↗
Role of peritubular capillary forces in the renal action of carbonic anhydrase inhibitor.
Micropuncture study was performed in Munich-Wistar rats to assess peritubular capillary Starling forces in renal superficial cortex during suppression of proximal fluid reabsorption by carbonic anhydrase inhibitor. Administration of benzolamide (2 mg/kg/hr, i.v., Group 1, N = 7 rats) caused not only reduction in absolute rate of proximal fluid reabsorption (APR, from 26.7 +/- 4.0 nl/min to 17.7 +/- 3.6, P less than 0.001), but also an increase in peritubular transcapillary hydraulic-pressure difference (from 10.0 +/- 0.5 mm Hg to 15.2 +/- 0.5, P less than 0.001). In a separate group of seven rats (Group 2), these parameters did not change significantly without benzolamide treatment. In Group 1 rats, an attempt was made to nullify the benzolamide-induced reduction in the peritubular capillary net reabsorptive forces by infusing hyperoncotic high-hematocrit blood. Following this treatment, while benzolamide administration was continued, values for APR returned to levels (25.6 +/- 4.8 nl/min) nearly identical to those measured prior to benzolamide administration, in association with a rise in peritubular transcapillary oncotic pressure difference. A separate group of six rats treated in a fashion identical to that of Group 1 showed continued suppression of carbonic anhydrase activity following blood infusion as indicated by low levels of whole kidney bicarbonate reabsorption rate. Peritubular capillary reabsorption coefficient was calculated based on the measured values for Starling forces in Group 1 and were unaffected throughout the study. Continued benzolamide administration alone without the treatment of hyperoncotic blood did not change APR significantly (Group 3, N = 7 rats).(ABSTRACT TRUNCATED AT 250 WORDS)
Animals↗
A simple procedure for the preparation of fritless columns by entrapping conventional high performance liquid chromatography sorbents.
A rapid and direct method for immobilizing conventional high performance liquid chromatography (HPLC) packing material inside fritless capillaries has been developed. Due to the simple composition of the entrapment matrix (tetraethoxysilane, alkyltriethoxysilane, ethanol and water), straightforward manufacturing procedure and modest equipment requirement, the method can readily be transferred to any laboratory and easily automated. The entrapment procedure has minimal influence on the structure and chromatographic properties of the original reverse-phase sorbent. Various immobilization solutions have been tested, and a comparison between columns entrapped with different immobilization mixtures and conventional packed capillaries is presented. High efficiency separations were obtained using tert-butyl-triethoxysilane entrapped columns in both capillary electrochromatography (reduced plate heights of 1.1-1.4 were measured) and microliquid chromatography (reduced plate heights of 2.2-2.6 were observed) formats. Elimination of frits, stabilization of the packed bed and on-the-fly customization of column length render mechanically robust columns that are remarkably stable over time, from which manufacturing imperfections can be removed easily.
Capillary Action↗
Chemical stability of polyacrylamide-coating on fused silica capillary.
The chemical stability of polyacrylamide coatings on a fused silica capillary for capillary electrophoresis was investigated with respect to temperature of capillary and pH as well as salt concentration of running buffer solution by evaluating their effects on electroosmotic mobility. The capillary covalently bonded to linear polyacrylamide through Si-C linkage was stable in buffer solutions of pH 2.3-8.0 at 30 degrees C for 30 days, whereas the capillary bonded through Si-O-Si-C linkage was damaged at pH above 4.6. The electroosmotic mobility observed in both capillaries increased with increasing temperature, though the degree of increase was smaller in the Si-C linked capillary than in the Si-O-Si-C linked capillary. The increase in the buffer concentration resulted in increased electroosmotic mobility in the Si-O-Si-C linked capillary, but no effect was observed for the Si-C linked capillary.
Acrylic Resins↗
Analysis of electro-osmotic flow characteristics at joint of capillaries with step change in zeta-potential and dimension.
The Navier-Stokes equation was used to describe the characteristics of electro-osmotic flow. The corresponding numerical simulations were performed for varying zeta-potential and dimension. The results indicated that a step change in zeta-potential will cause a significant variation in the velocity profile and pressure distribution of the flow. A step change both in zeta-potential and dimension will result in a more violent variation near the joint of the capillary. This variation will reduce the separation efficiency and quality of capillary electrophoresis. The conclusions are helpful to design and fabrication of microfluidic devices, the analysis of data collected from such devices and improvement of the separation efficiency of capillary electrophoresis.
Capillary Action↗
Mechanism of action of tablet disintegrants.
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Absorption↗
Protective effect of a purified flavonoid fraction against reactive oxygen radicals. In vivo and in vitro study.
S 5682 is a purified flavonoid fraction containing 90% diosmin (flavone derivative) and 10% hesperidin (flavanone derivative). In this study the scavenging properties of S 5682 on active oxygen radicals were demonstrated in vivo and in vitro. The activity of intravenous S 5682 was evaluated in the rat by measuring the degree of hyperglycemia provoked by an intravenous injection of alloxan, the metabolism of which produces active oxygen radicals which are toxic to B cells of the pancreas. S 5682 produced a decrease in the hyperglycemia in a dose-dependent manner (25 mg/kg and 50 mg/kg). The production in vitro of active oxygen radicals during phagocytosis by polymorphonuclear cells and macrophages is accompanied by emission of photons which can be amplified in the presence of luminol. Measurement of this chemiluminescence is a way of determining the quantity of active oxygen radicals generated in the medium, this may be reduced either by a decrease in production or by an increase in neutralisation through a reducing effect. Results demonstrated that S 5682 had a scavenging effect on active oxygen radicals for concentrations between 2 x 10(-8) mol/l and 2 x 10(-4) mol/l. The concentration of S 5682 reducing the chemiluminescence by 50% was 1.6 x 10(-5) mol/l. These scavenging properties imply that S 5682 has a pharmacological action on capillary hyperpermeability as well as an anti-inflammatory and anti-oedematous action.
Animals↗
The separation and determination of quinine in bitter drinks by micellar electrokinetic capillary chromatography.
A rapid method for the determination of quinine in bitter drinks by micellar electrokinetic capillary chromatography (MECC) with ultraviolet (UV) detection is described. The beverage is simply diluted with deionized water, filtered, and analyzed using a 75 cm x 75 micrometer uncoated fused-silica capillary column with a buffer consisting of 15% methanol and 85% of a mixture of 0.05 M cetyltrimethylammonium bromide (CTAB), 0.01 M sodium tetraborate, and 0.01 M potassium dihydrogen orthophosphate, pH 8.6, with an operating voltage of -25 kV. The levels of quinine determined by MECC were in good agreement with those determined by HPLC. The CVs for area calculation (2.1%, n = 7) and migration time variation (1.3%, n = 20) for multiple injections of a sample solution by MECC were satisfactory.
Antimalarials↗
Nanoliter capillary electrochromatography columns based on collocated monolithic support structures molded in poly(dimethyl siloxane).
Following current trends in miniaturization of analytical chemistry, an inexpensive disposable analytical tool in the form of a liquid chromatography column fabricated on a poly(dimethyl siloxane) (PDMS) chip was created. Ease of fabricating the chromatography column was demonstrated by molding collocated monolithic support structures (COMOSS) directly in the column. Positive photo-resist, SPR 220, was used to create column structures on a negative relief master providing final channel dimensions of 2.7-5.2 microm wide by 10.0 microm deep, while monolithic dimensions were 9.8 x 9.8 x 10.0 microm - 12.3 x 12.3 x 10.0 microm. The ability to separate biological samples such as peptides from a tryptic digest of fluorescein isothiocyanate labeled bovine serum albumin (FITC-BSA) was shown. Separations in capillary electrochromatographic (CEC) mode were performed yielding column efficiencies of 4.0 x 10(5) plates/m.
Animals↗
[Local action of adrenaline and acetylcholine on the capillary reactivity of patients with diencephalic disorders].
The local action of adrenaline and acetylcholine was studied capillaroscopically and capillarographically in 30 patients with diencephalic disorders. An abnormal capillary reactivity was present difficult to affect by the action of specific irritant as adrenaline and acetylcholine. The problem of the atypical changes in capillaroscopic and capillarographic status under the action of adrenaline and acetylcholine is discussed with consideration given to the diencephalic disorders advanced--central and local.
Acetylcholine↗
Influence of capillary multifilament sutures on the antibacterial action of inflammatory cells in infected wounds.
Implants of two capillary multifilament suture materials, braided polyester and twisted polyamide with cover, in tissue infected with Staphylococcus aureus were studied with light microscopy and transmission electron microscopy. In the tissue around both suture materials there was a pronounced inflammatory cell reaction. Staphylococci were found between the filaments of both materials. Some ingrowth of granulation tissue with inflammatory cells close to the exterior thread surface was seen in braided polyester suture. No such infiltration was seen in the suture consisting of twisted polyamide with cover. Bacteriologic studies showed faster elimination of staphylococci from the braided polyester than from the twisted polyamide implants. The capacity of leukocytes to penetrate into a capillary multifilament material presumably is dependent on the structure of the suture thread. Bacteria which are enclosed in the interstices of multifilament suture material, and protected from the phagocytic activity of leukocytes, can sustain and prolong an infection.
Animals↗
Characterization of rat aortic fragment within collagen gel as an angiogenesis model; capillary morphology may reflect the action mechanisms of angiogenesis inhibitors.
A fragment of rat thoracic aorta within type I collagen gel was employed as a model of angiogenesis, including the processes of cell migration, proliferation and capillary tube formation. Endogenous angiogenic factors in this model were studied. Expressions of vascular endothelial growth factor (VEGF) and its receptor, and proteolytic enzyme activities (matrix metalloprotease-2; MMP-2 and plasminogen activator; PA) increased during angiogenesis. The angiogenesis was inhibited by VEGF receptor kinase inhibitor and MMP inhibitor, confirming that these endogenous factors played an important role in angiogenesis. Interestingly, these inhibitors induced different capillary morphologies, including differences of cell migration and sprouting. Furthermore, dexamethasone (a down-regulator of MMP and PA) and TNP-470 (an endothelial cell growth inhibitor) induced another capillary morphology. The results suggest that the capillary structure in this model is dramatically influenced by the inhibition of angiogenic signalling and extracellular matrix (ECM) degradation. We also found that a novel angiogenesis inhibitor, the microbial metabolite luminacin, which was recently identified by us (Wakabayashi et al., J. Antiobiot., 53, 591-596 (2000)), induced a different morphology compared with other inhibitors examined, suggesting that it has a unique mechanism of action. Our results indicate that this rat aorta model should be useful for screening novel angiogenesis inhibitors.
Angiogenesis Inhibitors↗
Micellar electrokinetic capillary chromatography combined with immunoaffinity chromatography for identification and determination of dexamethasone and flumethasone in equine urine.
A capillary electrophoresis technique was developed for the separation of synthetic glucocorticoids and the determination of dexamethasone and flumethasone in horse urine. Pretreatment of the sample using a dexamethasone affinity column resulted in low background that enabled the authors to detect levels as low as 1.1 ng/mL and 2.7 ng/mL for dexamethasone and flumethasone in horse urine, respectively. The developed method was used to detect dexamethasone in horse urine samples after the injection of a therapeutic dose of dexamethasone for up to 12 hr postinjection. The optimum conditions for capillary electrophoresis and dexamethasone elution from the affinity column are described.
Animals↗