Ecofriendly Long Life Nanocomposite Sensors for Determination of Carbachol in Presence of Choline: Application in Ophthalmic Solutions and Biological Fluids.

Several emerging nano scale forms of carbon are showing great promise in electrochemical sensing such as graphene and multi-walled carbon nanotubes (MWCNTs). Herein we present an ecofriendly method to fabricate long life and sensitive ion selective sensors based on graphene and MWCNTs nanocomposites with no need for volatile organic solvents. Both sensors were fabricated, for the analysis of carbachol in ophthalmic solutions, plasma and urine where ion- association complex was formed between cationic carbachol and anionic Sodium tetra phenyl borate (NaTBP) in a ratio 1:1. Both sensors were evaluated according to the IUPAC recommendation data, revealing linear response in the concentration range 10-7 M to 10-2 M with near Nernstian slopes 50.80 ± 5 and 58.14 ± 3 mV/decade and correlation coefficients 0.9992 and 0.9998 for graphene and MWCNTs based sensors, respectively. Both sensors were successfully applied as stability indicating method for the analysis of carbachol in presence of its metabolite choline, in ophthalmic preparations, in plasma and urine showing good recovery percentage values. MWCNTs based sensor showed some advantages over graphene sensor regarding lower limit of detection (LOD), longer life time and higher selectivity towards carbachol. Statistical comparison of the proposed sensors with the official method showed no significant difference for accuracy and precision.

Study of human serum albumin structure by dynamic light scattering: two types of reactions under different pH and interaction with physiologically active compounds.

The effect of pH and binding of ten physiologically active compounds (isoproterenol, yohimbine, propranolol, clonidine, phenylephrine, carbachol, tripeptide fMLP, diphenhydramine, chlorpromazine and atropine) on the molecular structure of human serum albumin (HSA) has been studied using the dynamic light scattering. It was found that albumin globule has the most compact configuration (Stokes diameter 59-62 A) at physiological pH 7.4. The changes in pH, both increase to 8.0 and decrease to 5.4, result in the growth of globule size to 72-81 A. At acidic shift of pH an additional peak arises in the correlation spectra caused by the light scattering on the structures with the Stokes diameters of 29-37 A. Those conform to the sizes of the albumin subdomains. The indicated peak is not displayed at basic shift of pH. The interaction with propranolol, clonidine, phenylephrine, carbachol and tripeptide fMLP which hinder adenylate cyclase (AdC) and activate Ca-polyphosphoinositide (Ca-PPI) signaling system of a cell initiates structural rearrangements similar to acidic transitions. Isoproterenol, yohimbine diphenhydramine, chlorpromazine and atropine, which activate AdC and hinder Ca-PPI, cause conformational changes of HSA similar to basic transitions.

Negative inotropic effect of chagasic IgG mediated by nitric oxide.

In this paper we analyse the interaction of IgG from T. cruzi infected patients with cardiac muscarinic acetylcholine receptors (mAChRs). Human chagasic IgG, activating M2 mAChR simulated the agonist actions excerting negative inotropic effect and stimulation of nitric oxide synthase (NOS). Inhibitors of phospholipase C, protein kinase C, calcium/calmodulin, NOS and guanylate cyclase activities prevented the chagasic effects upon contractility and NOS activity.

Negative inotropic effect of chagasic IGG mediated by nitric oxide

In this paper we analyse the interaction of IgG from T. cruzi infected patients with cardiac muscarinic acetycholine receptors (mAChRs). Human chagasic IgG, activating M2 mAChR simulated the agonist actions excerting negative inotropic effect and simulation of nitric oxide synthase (NOS). Inhibitos of phospholipase C, protein Kinase C, calcium/calmodulin, NOS and guanylate cyclase activities prevented the chagasis effects upon contractility and NOS activity.

Negative inotropic effect of chagasic IGG mediated by nitric oxide

In this paper we analyse the interaction of IgG from T. cruzi infected patients with cardiac muscarinic acetycholine receptors (mAChRs). Human chagasic IgG, activating M2 mAChR simulated the agonist actions excerting negative inotropic effect and simulation of nitric oxide synthase (NOS). Inhibitos of phospholipase C, protein Kinase C, calcium/calmodulin, NOS and guanylate cyclase activities prevented the chagasis effects upon contractility and NOS activity. (AU)

Drinking and natriuresis during volume expansion and intracranial angiotensin or carbachol.

Two methods of sodium loading were used to counteract the body fluid dilution resulting from natriuresis and water drinking during sustained lateral ventricular infusions of carbachol (CBC) or angiotensin II (ANG II) in rats. It was expected that preventing dilution would also prevent the precipitous decline of both drinking and natriuresis during the later hours of CBC infusion. In the first study, rats having isotonic saline as the sole drinking fluid during CBC infusions drank less fluid and had only slightly higher plasma osmolality and sodium concentration than rats drinking water, which showed extreme dilution. In the second study, rats with only water to drink were given intravenous infusions of 0.15, 0.45, or 1.00 M NaCl solutions at 1.8 ml/h concurrently with the intraventricular infusions. Significant dilution of plasma was found at the two lower rates but not at 1.00 M NaCl in CBC-infused rats. Only the latter group showed both persistent drinking and natriuresis throughout the 4-h infusion period, and this was not because of elevated plasma osmolality. Infusions of ANG II generated less severe body fluid dilution and more persistent drinking in both experiments. The study demonstrates that body fluid dilution may control the offset of both drinking and natriuresis during sustained infusions of CBC and that the more persistent drinking to ANG II vs. CBC probably occurs because of a lesser natriuresis and consequent fluid dilution.