Search results for "Molar concentration"

Rapid fluorimetric assay for primary amine groups in water samples

2003

Bond Elut C(18) solid-phase extraction cartridges were used for pre-concentration followed by derivatization with o-phthaldialdehyde-N-acetylcysteine (OPA-NAC) of primary amines in water. Optimal conditions were: conditioning the cartridges with borate buffer pH 10.4, retention of the primary amines, addition of the OPA-NAC(3.7 mmol L(-1)) 1:1 molar ratio and borate buffer pH 8, elution of the isoindol with MeOH-borate buffer (9:1) pH 10.2 and fluorescence measurement. The equations of the calibration graphs for methylamine, ethylamine, propylamine, butylamine, pentylamine, and beta-phenylethylamine at lambda(excitation)=330 nm and lambda(emission)=440 nm, in the optimal conditions are pres…

A minireview on NHE1 inhibitors. A rediscovered hope in oncohematology.

2015

Background: Na+/H+ exchanger-1 (NHE-1) is involved in pH regulation and is up-regulated in different malignancies. Activation of NHE-1 is one way for allowing cells to avoid intracellular acidification and protect them against apoptosis. Inhibitors of NHE-1 are able to decrease intracellular pH and induce apoptosis. Some statins can also act by partial inhibition of NHE-1. This review presents progress in understanding the mechanisms of action of these inhibitors, connections with certain genetic mutations and acquired treatment resistance, as well as new patents on them. Methods: A MEDLINE search for original and review articles using key terms, Na+/H+ exchanger, leukemia, cariporide, and …

Osmolality of various viscoelastic substances: comparative study.

2000

Abstract Purpose To determine the osmolality of various viscoelastic substances. Setting Department of Ophthalmology, Johannes Gutenberg-University, Mainz, and Institute for Medical Device Testing, Memmingen, Germany. Methods The analysis was carried out according to the European Pharmacopoeia by means of a calibrated osmometer using the freezing-point depression method. Each syringe was analyzed as a duplicate analysis. Results Mean osmolalities (mOsmol/kg) of the sodium hyaluronate viscoelastic substances were Allervisc® 299; Allervisc® Plus 307; Amvisc® Plus 335; AMO Vitrax® 284; Biolon® 279; Dispasan® 311; Dispasan® Plus 314; Healon® 295; Healon GV® 312; Healon®5 322; HYA-Ophtal® 376; M…

Hypoosmolar conditions reduce extracellular volume fraction and enhance epileptiform activity in the CA3 region of the immature rat hippocampus

2006

The osmolarity of the extracellular space (ECS) compartment is an important factor determining the excitability of neuronal tissue. In the adult hippocampus an important role of osmolarity and ECS diffusion parameters on the susceptibility to epileptic events is well established, but the influence of hypo- and hyperosmolar conditions on the immature hippocampus remains elusive. To investigate the influence of osmolarity on epileptiform activity, extracellular field potentials were recorded in the CA3 region of hippocampal slices of immature (postnatal days 4-7) Wistar rats. The ECS diffusion parameters were determined by the real-time tetramethylammonium (TMA+) iontophoretic method with ion…

NephroCheck: should we consider urine osmolality?

2019

Muscarinic mobilization of choline in rat brain in vivo as shown by the cerebral arterio-venous difference of choline.

1987

In anesthetized rats, the choline levels of cerebrospinal fluid and plasma obtained from blood collected from peripheral vessels (carotid artery, cardiac vessels) and from the transverse sinus were determined with a radioenzymatic assay. Cortical release of choline was studied using the "cup technique." The plasma choline level of the peripheral blood (11.5 mumol/L) was lower than that of the sinus blood. The resulting cerebral arterio-venous difference of choline was negative (3.2 mumol/L) and reflected the net release of choline from the whole brain. The plasma choline levels were not different irrespective of whether the rats were anesthetized with ether, urethane, or pentobarbital. Howe…

Modulation of central corneal thickness by various riboflavin eyedrop compositions in porcine corneas

2012

Purpose To evaluate the modulatory effect of various riboflavin 0.1% and 0.2% compositions on the central corneal thickness (CCT) in fresh porcine corneas. Setting Department of Ophthalmology, Johannes Gutenberg University of Mainz, Mainz, Germany. Design Experimental study. Methods The CCT in freshly enucleated porcine globes was measured by ultrasound pachymetry before and after (if applicable) deepithelialization and every 10 minutes thereafter during 120 minutes of eyedrop application. In Groups 1 and 2 (controls), no eyedrops were applied. In Groups 3 and 4, isotonic riboflavin eyedrops were used. In Groups 5 to 9, hypotonic riboflavin eyedrops were given. In Groups 10 and 11, preparat…

Modulation by docosahexaenoic acid of the epinephrine-stimulated adenylate cyclase activity of the bovine retina.

1988

This work shows that unsaturated fatty acids enhance the epinephrine-stimulated adenylate cyclase activity in bovine retina. The modulating effect on the epinephrine-stimulated formation of cyclic AMP seems to be linked to the degree of unsaturation of the fatty acid. Treatment of the intact retina with docosahexaenoic acid in the concentration range 0.5 X 10(-6)-1 X 10(-3) M does not affect the enzyme activity measured in the absence of the hormone but markedly increases the cyclase activity when the tissue is incubated in the presence of 0.1 mM epinephrine. Docosahexaenoic acid enhances the maximal response to epinephrine without affecting the apparent ED50 value for this effector. Docosa…