Orthogonal projection to latent structures and first derivative for manipulation of PLSR and SVR chemometric models' prediction: A case study.

Novel manipulations of the well-established multivariate calibration models namely; partial least square regression (PLSR) and support vector regression (SVR) are introduced in the presented comparative study. Two preprocessing methods comprising first derivatization and orthogonal projection to latent structures (OPLS) are implemented prior to modeling with PLSR and SVR. Quantitative determination of pyridostigmine bromide (PR) in existence of its two associated substances; impurity a (IMP A) and impurity b (IMP B); was utilized as a case study for achieving comparison. A series consisting of 16 mixtures with numerous percentages of the studied compounds was applied for implementation of a 3 factor 4 level experimental design. Additionally, a series consisting of 9 mixtures was employed in an independent test to verify the predictive power of the suggested models. Significant improvement of predictive abilities of the two studied chemometric models was attained via implementation of OPLS processing method. The root mean square error of prediction RMSEP for the test set mixtures was employed as a key comparison tool. About PLSR model, RMSEP was found 0.5283 without preprocessing method, 1.1750 when first derivative data was used and 0.2890 when OPLS preprocessing method was applied. With regard to SVR model, RMSEP was found 0.2173 without preprocessing method, 0.3516 when first derivative data was used and 0.1819 when OPLS preprocessing method was applied.

Novel potent pyridoxine-based inhibitors of AChE and BChE, structural analogs of pyridostigmine, with improved in vivo safety profile.

We report a novel class of carbamate-type ChE inhibitors, structural analogs of pyridostigmine. A small library of congeneric pyridoxine-based compounds was designed, synthesized and evaluated for AChE and BChE enzymes inhibition in vitro. The most active compounds have potent enzyme inhibiting activity with IC50 values in the range of 0.46-2.1µM (for AChE) and 0.59-8.1µM (for BChE), with moderate selectivity for AChE comparable with that of pyridostigmine and neostigmine. Acute toxicity studies using mice models demonstrated excellent safety profile of the obtained compounds with LD50 in the range of 22-326mg/kg, while pyridostigmine and neostigmine are much more toxic (LD50 3.3 and 0.51mg/kg, respectively). The obtained results pave the way to design of novel potent and safe cholinesterase inhibitors for symptomatic treatment of neuromuscular disorders.

Possibility of usage of aminostigmine structural analogue for the treatment of toxic cognitive disorders.

We studied the effects of 2-(hexyl(methyl)amino)methyl)pyridyl-3-dimethyl carbamate (OPDC), a structural analogue of aminostigmine oxalate, on memory formation in rats with toxic scopolamine-induced amnesia. It was shown that OPDC in non-toxic doses ((1)/215 LD50) has significant anti-amnesic action. Ipidacrine and galantamine in the doses similar to toxic doses ((1)/17 and (1)/6 of LD50, respectively) induced the retention of memory trace. Administration of aminostigmine ((1)/11 of LD50) induced unstable anti-amnesic effect in the model of scopolamine-induced amnesia.

[Bizerine: new anticholinesterase drug with selective gastrointestinal action].

Bizerine-oxalate of hexamethylene-bic-[N-methylcarbamic acid-3-(2-dimethylaminomethyl)pyridyl ether] exhibits the properties of acetylcholine esterase (AChE) inhibitor, being comparable in this respect in in vitro tests to aminostigmine. Bizerine is 2.5 and 6.7 times less active in these tests than proserine and distigmine, respectively, but it forms more stable complex with the enzyme. Bizerine is 10-80 times less toxic for laboratory mammals as compared to prozerine; it is 3-60 times more active on the isolated urinary bladder of rats, but it is 100-500 times less effective on the spinal muscle of leeches and skeletal muscles of mice and rats. Bizerine actively inhibits intestinal cholinesterase (ChE) of guinea pigs. In systematic use, it does not inhibit brain ChE of mice. Bizerine is a prolonged peripheral muscarinic potentiating inhibitor of ChE and activator of intestinal peristalsis.

Accommodation of physostigmine and its analogues by acetylcholinesterase is dominated by hydrophobic interactions.

The role of the functional architecture of the HuAChE (human acetylcholinesterase) in reactivity toward the carbamates pyridostigmine, rivastigmine and several analogues of physostigmine, that are currently used or considered for use as drugs for Alzheimer's disease, was analysed using over 20 mutants of residues that constitute the interaction subsites in the active centre. Both steps of the HuAChE carbamylation reaction, formation of the Michaelis complex as well as the nucleophilic process, are sensitive to accommodation of the ligand by the enzyme. For certain carbamate/HuAChE combinations, the mode of inhibition shifted from a covalent to a noncovalent type, according to the balance between dissociation and covalent reaction rates. Whereas the charged moieties of pyridostigmine and rivastigmine contribute significantly to the stability of the corresponding HuAChE complexes, no such effect was observed for physostigmine and its analogues, phenserine and cymserine. Moreover, physostigmine-like ligands carrying oxygen instead of nitrogen at position -1 of the tricyclic moiety (physovenine and tetrahydrofurobenzofuran analogues) displayed comparable structure-function characteristics toward the various HuAChE enzymes. The essential role of the HuAChE hydrophobic pocket, comprising mostly residues Trp(86) and Tyr(337), in accommodating (-)-physostigmine and in conferring approximately 300-fold stereoselectivity toward physostigmines, was elucidated through examination of the reactivity of selected HuAChE mutations toward enantiomeric pairs of different physostigmine analogues. The present study demonstrates that certain charged and uncharged ligands, like analogues of physostigmine and physovenine, seem to be accommodated by the enzyme mostly through hydrophobic interactions.

[Criminal clozapine intoxications].

The paper deals with the topical problem--study criminal clozapine intoxications that have recently ranked first in the total structure of criminal intoxications, by ousting poisoning by clofelin. Thus, in 2004 to 2006, the number of victims taken to the Prof. A. A. Ostroumov Moscow City Hospital No. 33 increased by 1.9 times, by amounting to 1120 cases in 2006. At the same time, its correct prehospital diagnosis was made only in 1.76% of the victims. Abundant clinical material (2720 cases) has been analyzed, by using the currently performed studies. The specific features of the development and clinical manifestations of these intoxications, including those concurrent with alcoholic intoxication, are described in detail. The characteristic manifestations of impaired consciousness, hypersalivation, and myosis in the absence of generally, respiratory failure and hemodynamic disorders, as well as altered clinical and biochemical blood parameters are shown. At the same time there were elevated ammonia levels within the first hours after intoxication, which, in the authors' opinion, may suggest the development of hepatic dysfunction. Emphasis is laid on the fact that the leading component in the complex of medical measures is the administration of central anticholinesterase agents (aminostigmine and galantamine hydrobromide) that may be used as an antidote and for the differential diagnosis of these intoxications.

Bifunctional compounds eliciting both anti-inflammatory and cholinergic activity as potential drugs for neuroinflammatory impairments.

We tested two novel bifunctional compounds: ibuprofen-N-octyl-pyridostigmine bromide (IBU-PO) and ibuprofen-N-decyl-pyridostigmine bromide (IBU-PD). They both contain a non-steroidal anti-inflammatory drug (NSAID), ibuprofen (IBU) and pyridostigmine (PO), a cholinesterase inhibitor that acts as a cholinergic up-regulator (CURE). The two moieties are conjugated by a hydrocarbon spacer consisting of 8 (octyl) and 10 (decyl) carbons, respectively. The compounds were tested for their efficiency in reducing the neurological symptoms observed in experimental autoimmune encephalomyelitis induced in mice by myelin oligodendrocyte glycoprotein (MOG). IBU-PO and IBU-PD significantly ameliorated the clinical score (a 40-50% reduction in disease severity) over a period of 30 days, following daily administration of 1 and 0.1mg/kg, i.p., respectively. Clinical improvement was accompanied by reduced responsiveness of MOG-specific T-cells. In addition, IBU-PO and IBU-PD down-regulated the production of nitric oxide (NO) and prostaglandin E2 (PGE2) in cultured astrocytes. To determine which moiety was responsible for these effects, we tested each of the two components, IBU and PO. Our findings indicate that combining NSAID with cholinergic intervention contributes an added therapeutic value for each distinct entity and that these bifunctional compounds act both on the peripheral immunological system and on the central nervous system (CNS) inflammatory pathways.

[The influence of aminostigmine on the parameters of nonspecific resistance and immune system of the organism upon acute poisoning of benzyl 3-quinuclidylate].

The results of experiments on outbred rats weighing 180 -240 g showed that the acute poisoning with benzyl 3-quinuclidylate decreases the parameters of nonspecific resistance of the organism, reduces the antibody production mainly to T-dependent antigens (sheep red blood cells), decreases the activity of natural killers and the antibody-dependent cell-mediated cytotoxicity, and suppresses the formation of delayed-type hypersensitivity. Aminostigmine partly inhibits the immunotoxicity benzyl 3-quinuclidylate.

[Histamine blockers increase efficacy of specific antidote prophylaxis of intoxication by cholinesterase inhibitors in mice]. / Gistaminoblokatory povyshaiut éffektivnost' spetsificheskoi antidotnoi profilaktiki otravlenii myshei inhibitorami kholinésterazy.

Dimedrol and pipolphen, but not loratadine, increase efficacy of the atropine and dipiroxime treatment of mice--an antidote prophylaxis against their intoxication with phosphacol and aminostigmine. The results of experiments confirm a hypothesis that histamine participates in the formation of secondary toxicity reactions in the case of heavy poisoning with anticholinesterase agents.

[Effects of acetylcholine and histamine on leukocyte and neutrophil numbers in the endometrium of rats in various phases of the estrous cycle (by imprints)]. / Vliianie atsetilkholina i gistamina na kolichestvo limfotsitov i neitrofilov v éndometrii matki krys v razlichnye fazy éstral'nogo tsikla (po otpechatkam).

Administration of the acetylcholine esterase antagonist aminostigmin increased the number of neutrophils in the estrus phase and the number of lymphocytes in the diestrus phase in rats. Histamine decreased both the neutrophils and lymphocytes at all stages of the estrus cycle in the uterus endometrium.

[Protection of mice by carbamates cholinesterase inhibitors against poisoning by armin and its dependence on certain physico-chemical indicators]. / Zashchita myshei ingibitorami kholinésterazy iz klassa karbamatov ot otravleniia arminom i zavisimost' ot nekotorykh fiziko-khimicheskikh pokazatelei.

A series of aminostigmin derivatives with various substituents at nitrogen in the second position of the pyridine ring, has been tested. The efficacy of preventing the death of mice poisoned by armine in five of the seven substances correlates with the constant of the rate of carbamylation of acetylcholinesterase in the in vitro experiments and with the hydrophobic nature. It is suggested that the phenomenon of protection of animals against the toxic effect of organophosphorous compounds involves the "leaving portion" of the molecule of carbamates.

[New data on the pharmacokinetics of aminostigmine]. / Novye dannye o farmakokinetike aminostigmina.

The results of studying the pharmacokinetics of aminostigmine, a new reversible cholinesterase inhibitor produced in Russia, are discussed. Tissue radioactivity after intragastric administration of a toxic dose of aminostigmine was quite quickly absorbed from the intestinal lumen. The half-life period of aminostigmine exceeded considerably that of earlier studied carbamates and correlated with the clinical manifestations of the drug effects. This confirms that the use of aminostigmine in the treatment of neurologic and somatic diseases is preferable.

Studies of the role of the brain cholinergic system in the mechanisms of dissociative learning.

Rats were trained to make conditioned food reflex excursions in two states: in normal conditions and on a background of treatment with pharmacological agents producing dissociative states. A number of cholinergic substances were completely interchangeable in dissociative learning; anticholinergic compounds efficiently neutralized the ability of cholinergic substances to produce dissociative states; muscarinic cholinoreceptors played the leading role in production of the dissociative state.

[Biochemical characteristics of aminostigmine--a new anticholinesterase agent]. / Biokhimicheskaia kharakteristika aminostigmina--novogo lekarstvennogo antikholinésteraznogo sredstva.

The properties of aminostigmine in comparison with those of other carbamate inhibitors of cholinesterases have been studied in vitro using potentiometric titration and Ellman methods. The bimolecular constants of the inhibition rate of acetyl-, butyryl- and propionylcholinesterase were found to be equal to (8.0-14.0).10(5) (3.8-7.7).10(5) and 11.0.10(5) M-1.min-1, respectively. In terms of inhibitory activity, aminostrigmine is comparable to neostigmine methylsulphate, being inferior to physostigmine and superior to pyridistigmine. The rate of decarbamylation of acetylcholinesterase inhibited by aminostigmine measured by the dilution method, by creating excessive acetylcholine and by dialysis is characterized by k2c constants equal to (1.1-1.6).10(-2), (2.5-2.8).10(-2) and 0.025.10(-2) min-1, respectively. On the whole, aminostigmine belongs to slowly reversible inhibitors. Being carbamylated by aminostigmine, the enzyme is resistant to reactivation by TMB-4 and HI-6. At (4-6).10(-7) M aminostigmine prevents by 50% the irreversible binding of cholinesterase by certain organophosphate inhibitors of cholinesterase when the latter are used at concentrations needed to inhibit the enzymatic activity by 85-90%.

[The comparative clinico-experimental characteristics of aminostigmine and galanthamine used for treating poisonings by choline-blocking substances]. / Sravnitel'naia kliniko-éksperimental'naia kharakteristika aminostigmina i galantamina, ispol'zuemykh dlia lecheniia otravlenii kholinoblokiruiushchimi veshchestvami.

The results of application of cholinesterase inhibitors, aminostigmin and galantamin, for treatment of acute poisoning with cyclodol, dimedrol, and solutan of moderately grave condition are presented. Aminostigmin was shown to exhibit the more pronounced stable and universal effect. The experiments in animals showed that aminostigmine affected peripheral and central M-cholinoreactive structures and conjugated with them more actively than galantamin. Aminostigmin, but not galantamin increases the rate of dopamine circulation and content of cyclic guanozinemonophosphate in frontal brain of rats, and this effect is exhibited even under the conditions of N-cholinoreceptor blockade with amizyl.

[Aminostigmine-a novel drug against home poisoning]. / Primenenie novogo lekarstvennogo sredstva aminostigmina v terapii bytovykh otravlenii.

Aminostigmin, a novel reversible inhibitor of cholinesterase developed in Russia, has been tried in management of poisoning with cholinolytyics, antihistamine drugs, tricycle antidepressants and derivatives of 1,4-benzodiazepine. The treatment of 144 patients with aminostigmin and 20 patients with galantamin showed close to similar efficacy of these drugs. The scheme of aminostigmin administration is proposed warranting fast relief of cholinolytic syndrome in subjects poisoned with cholinolytics, antihistamine drugs and antidepressants. Benzodiazepines poisoning was unresponsive to aminostigmin. Rare side effects were caused by overdose. Aminostigmin is an effective antidote in cholinolytic poisoning.

[The toxicological characteristics of the interaction of cholinolytics with aminostigmine--a new reversible cholinesterase inhibitor]. / Toksikologicheskaia kharakteristika vzaimovliianiia kholinolitikov s aminostigminom--novym obratimym ingibitorom kholinesterazy.

This investigation has been carried out on albino mice. In the first series of experiments, we determined the dependence of LD50 of aminostigmine on different doses of 10 cholinolytics, and conversely, the dependence of LD50 of cholinolytics on aminostigmine administration. The initial slopes of the dose-effect curves were calculated. This data form the basis for evaluation of the character and degree of interactions. We established that benactyzine, spasmolytin, ftoracizin, arpenal, atropine, ganglerone, and methacin at low doses exhibit antagonism (with decreasing activity), whereas at high doses they exhibit synergism to the toxic effect of aminostigmine. In the interaction with aminostigmine, pirenzepine and amitriptyline (M1--cholinolytics) reveal a slightly pronounced antagonism, whereas aetyrophene, a selective central N-cholinolytic, displays mutual synergism. In the second series of experiments we showed that a combination of M1-, M2-cholinolytic atropine with M1- cholinolytics does not change the efficacy of the prophylaxis of aminostigmine and physostigmine poisoning, whereas a combination with N-cholinolytic increases it.

[Aminostigmine as a cholinesterase inhibitor and as an agent for treating poisonings by cholinergic blockers]. / Aminostigmin kak ingibitor kholinésterazy i kak sredstvo dlia lecheniia otravlenii kholinoblokatorami.

Experiments on non-inbred albino mice have demonstrated that aminostigmine is an active reversible centrally active cholinesterase inhibitor close to the properties of physostigmine, but greatly superior to it in its action duration. Clinical examinations of healthy volunteers and patients have shown that aminostigmine-induced inhibition of cholinesterase activity persists 6 hours. The agent have been found to be more highly effective in treating cholin blocker-induced intoxications than galanthamine, which manifests itself in its greater stability of the therapeutical effect achieved and in its higher ability to prevent cardiovascular events occurring in intoxication.

[The pharmacological characteristics of the new anticholinesterase drug aminostigmine]. / Farmakologicheskaia kharakteristika novogo antikholinésteraznogo lekarstvennogo sredstva aminostigmina.

The pharmacological properties of a new drug approved in the USSR for the treatment of cholinolytics poisonings are described. The drug is as active as physostigmine. However, its action is longer. Aminostigmine exhibits marked central effects, which forms the basis for its use for elimination of brain dysfunctions caused by choline blockers.

A novel tertiary pyridostigmine derivative [3-(N,N-dimethylcarbamyloxy)-1-methyl-delta 3-tetrahydropyridine]: anticholinesterase properties and efficacy against soman.

In an effort to develop an effective centrally acting pretreatment compound against organophosphorus poisons, the tertiary pyridostigmine (Pyr) derivative 3-(N,N-dimethyl-carbamyloxy)-1-methyl-delta 3-tetrahydropyridine (THP) was synthesized and studied for its anticholinesterase properties, as well as its efficacy against soman intoxication in guinea pigs. Injection of THP (262 micrograms/kg, im) into adult male guinea pigs caused inhibition of blood (30%) and brain (25%) acetylcholinesterase (AChE), showing that THP penetrates the blood-brain barrier. Pyr (131 micrograms/kg, im) caused AChE inhibition in the blood (59%), but not in the brain. The inhibitory potencies of THP and Pyr were compared by determining their IC50 values for in vitro inhibition of both AChE (brain, erythrocyte) and pseudo-cholinesterase (plasma) in three mammalian species (guinea pig, rat, rabbit). THP, although effective in inhibiting both types of cholinesterase, was in general less potent than Pyr. Pretreatment of guinea pigs with THP (262 micrograms/kg, im) plus Pyr (131 micrograms/kg, im), 30 min prior to subcutaneous soman challenge, with no antimuscarinic or oxime treatment, protected 60% of the animals against 2 X LD50 of soman. Neither THP nor Pyr alone was effective. The protective pretreatment regimen did not prevent convulsions, but shortened the recovery time in surviving animals (median recovery time 1.6 hr, compared to 24 hr in control and other groups of animals pretreated with THP or Pyr alone). A combination of THP and Pyr thus appears to provide a means of evaluating the relative importance of selective peripheral plus central vs peripheral AChE protection against soman.