The use of bispyridinium non-oxime analogues for the restoration of nerve agent impaired neuromuscular transmission in rat hemidiaphragms - Structure optimization.

Organophosphate pesticide poisoning challenges health care systems worldwide. Furthermore, nerve agents remain a continuous threat. The treatment options for organophosphate poisoning have virtually been unchanged for decades, relying on symptomatic treatment and the use of oximes to indirectly restore neuromuscular function. Hence, compounds targeting directly nicotinic acetylcholine receptors (nAChRs) might substantially improve treatment options. The current study investigated a series of bispyridinium analogues with a trimethylene or 2,2'-diethyloxy linker in a rat hemidiaphragm model, using indirect field stimulation. Methyl- and ethyl-substituted bispyridinium analogues restored neuromuscular function up to 37 ± 17% (MB419, a 3-methyl analogue) at a stimulation frequency of 20 Hz. The bispyridinium analogues with a 2- or 3-methyl group, or a 2- or 3-ethyl group, tended towards a higher restoration of neuromuscular function than those with a 4-methyl or 4-ethyl group, respectively. The current data can be used for future studies to optimize structure-based molecular modeling of compounds targeting the nAChR.

Restoration of nerve agent impaired neuromuscular transmission in rat diaphragm by bispyridinium non-oximes - Structure-activity relationships.

Organophosphate (OP) poisoning is currently treated with atropine, oximes and benzodiazepines. The nicotinic signs, i.e., respiratory impairment, can only be targeted indirectly via the use of oximes as reactivators of OP-inhibited acetylcholinesterase. Hence, compounds selectively targeting nicotinic acetylcholine receptors (nAChRs) might fundamentally improve current treatment options. The bispyridinium compound MB327 has previously shown some therapeutic effect against nerve agents in vitro and in vivo. Nevertheless, compound optimization was deemed necessary, due to limitations (e.g., toxicity and efficacy). The current study investigated a series of 4-tert-butyl bispyridinium compounds and of corresponding bispyridinium compounds without substituents in a rat diaphragm model using an indirect field stimulation technique. The length of the respective linker influenced the ability of the bispyridinium compounds to restore muscle function in rat hemidiaphragms. The current data show structure-activity relationships for a series of bispyridinium compounds and provide insight for future structure-based molecular modeling.

Influence of Experimental End Point on the Therapeutic Efficacy of Essential and Additional Antidotes in Organophosphorus Nerve Agent-Intoxicated Mice.

The therapeutic efficacy of treatments for acute intoxication with highly toxic organophosphorus compounds, called nerve agents, usually involves determination of LD50 values 24 h after nerve agent challenge without and with a single administration of the treatment. Herein, the LD50 values of four nerve agents (sarin, soman, tabun and cyclosarin) for non-treated and treated intoxication were investigated in mice for experimental end points of 6 and 24 h. The LD50 values of the nerve agents were evaluated by probit-logarithmical analysis of deaths within 6 and 24 h of i.m. challenge of the nerve agent at five different doses, using six mice per dose. The efficiency of atropine alone or atropine in combination with an oxime was practically the same at 6 and 24 h. The therapeutic efficacy of the higher dose of the antinicotinic compound MB327 was slightly higher at the 6 h end point compared to the 24 h end point for soman and tabun intoxication. A higher dose of MB327 increased the therapeutic efficacy of atropine alone for sarin, soman and tabun intoxication, and that of the standard antidotal treatment (atropine and oxime) for sarin and tabun intoxication. The therapeutic efficacy of MB327 was lower than the oxime-based antidotal treatment. To compare the 6 and 24 h end points, the influence of the experimental end point was not observed, with the exception of the higher dose of MB327. In addition, only a negligible beneficial impact of the compound MB327 was observed. Nevertheless, antinicotinics may offer an additional avenue for countering poisoning by nerve agents that are difficult to treat, and synthetic and biological studies towards the development of such novel drugs based on the core bispyridinium structure or other molecular scaffolds should continue.

Molecular determinants of binding of non-oxime bispyridinium nerve agent antidote compounds to the adult muscle nAChR.

Organophosphorus nerve agents (NAs) are the most lethal chemical warfare agents and have been used by state and non-state actors since their discovery in the 1930s. They covalently modify acetylcholinesterase, preventing the breakdown of acetylcholine (ACh) with subsequent loss of synaptic transmission, which can result in death. Despite the availability of several antidotes for OPNA exposure, none directly targets the nicotinic acetylcholine receptor (nAChR) mediated component of toxicity. Non-oxime bispyridinium compounds (BPDs) have been shown previously to partially counteract the effects of NAs at skeletal muscle tissue, and this has been attributed to inhibition of the muscle nAChR. Functional data indicate that, by increasing the length of the alkyl linker between the pyridinium moieties of BPDs, the antagonistic activity at nAChRs can be improved. Molecular dynamics simulations of the adult muscle nAChR in the presence of BPDs identified key residues likely to be involved in binding. Subsequent two-electrode voltage clamp recordings showed that one of the residues, εY131, acts as an allosteric determinant of BPD binding, and that longer BPDs have a greater stabilizing effect on the orthosteric loop C than shorter ones. The work reported will inform future design work on novel antidotes for treating NA exposure.

Influence of experimental end point on the therapeutic efficacy of the antinicotinic compounds MB408, MB442 and MB444 in treating nerve agent poisoned mice - a comparison with oxime-based treatment.

Therapeutic efficacy of antidotal treatment of acute poisoning by nerve agents is generally assessed by the evaluation of LD50 values of nerve agents over 24 h following poisoning without or with a single administration of antidotal treatment. In this study, LD50 values of four nerve agents (sarin, soman, tabun and cyclosarin) for non-treated and treated poisoning were evaluated in mice for two experimental end points - 6 h and 24 h. While the efficacy of atropine or oxime-based antidotal treatment was the same regardless of the experimental end point, the therapeutic efficacy of all three newly developed bispyridinium non-oxime compounds (MB408, MB442, and MB444) was mostly slightly higher at the 6 h end point compared to the 24 h end point, although the therapeutic efficacy of MB compounds was not superior to oxime-based antidotal treatment. These results contrast with a study in guinea-pigs using a structurally-related compound, MB327, which showed a striking increase in protection at 6 h compared to 24 h. It is suggested that the disparity may be due to pharmacokinetic differences between the two animal species.

3-Quinuclidinyl-α-methoxydiphenylacetate: A multi-targeted ligand with antimuscarinic and antinicotinic effects designed for the treatment of anticholinesterase poisoning.

Racemic 3-quinuclidinyl-α-methoxydiphenylacetate (MB266) was synthesised. Its activity at muscarinic acetylcholine receptors (mAChRs), and muscle and neuronal nicotinic acetylcholine receptors (nAChRs), was compared to that of atropine and racemic 3-quinucidinyl benzilate (QNB) using a functional assay based on agonist-induced elevation of intracellular calcium ion concentration in CN21, Chinese Hamster Ovary (CHO) and SHSY5Y human cell lines. MB266 acted as an antagonist at acetylcholine receptors, displaying 18-fold selectivity for mAChR versus nAChR (compared to the 15,200-fold selectivity observed for QNB). Thus O-methylation of QNB reduced the affinity for mAChR antagonism and increased the relative potency at both muscle and neuronal nAChRs. Despite MB266 having a pharmacological profile potentially useful for the treatment of anticholinesterase poisoning, its administration did not improve the neuromuscular function in a soman-poisoned guinea-pig diaphragm preparation pretreated with the organophosphorus nerve agent soman. Consideration should be given to exploring the potential of MB266 for possible anticonvulsant action in vitro as part of a multi-targeted ligand approach.

Assessment of false transmitters as treatments for nerve agent poisoning.

Nerve agents inhibit acetylcholinesterase (AChE), leading to a build-up of acetylcholine (ACh) and overstimulation at cholinergic synapses. Current post-exposure nerve agent treatment includes atropine to treat overstimulation at muscarinic synapses, a benzodiazepine anti-convulsant, and an oxime to restore the function of AChE. Aside from the oxime, the components do not act directly to reduce the overstimulation at nicotinic synapses. The false transmitters acetylmonoethylcholine (AMECh) and acetyldiethylcholine (ADECh) are analogs of ACh, synthesised similarly at synapses. AMECh and ADECh are partial agonists, with reduced activity compared to ACh, so it was hypothesised the false transmitters could reduce overstimulation. Synthetic routes to AMECh and ADECh, and their precursors, monoethylcholine (MECh) and diethylcholine (DECh), were devised, allowing them to be produced easily on a laboratory-scale. The mechanism of action of the false transmitters was investigated in vitro. AMECh acted as a partial agonist at human muscarinic (M1 and M3) and muscle-type nicotinic receptors, and ADECh was a partial agonist only at certain muscarinic subtypes. Their precursors acted as antagonists at muscle-type nicotinic, but not muscarinic receptors. Administration of MECh and DECh improved neuromuscular function in the soman-exposed guinea-pig hemi-diaphragm preparation. False transmitters may therefore help reduce nerve agent induced overstimulation at cholinergic synapses.

Some benefit from non-oximes MB408, MB442 and MB444 in combination with the oximes HI-6 or obidoxime and atropine in antidoting sarin or cyclosarin poisoned mice.

The effect of three newly developed bispyridinium non-oxime compounds (MB408, MB442, and MB444) on the therapeutic efficacy of a standard antidotal treatment (atropine in combination with the oxime HI-6 or obidoxime) of acute poisoning by two nerve agents (sarin and cyclosarin) in mice was studied. The therapeutic efficacy of atropine in combination with an oxime with or without one of the bispyridinium non-oximes was evaluated by determination of the 24 h LD50 values of the nerve agents studied and by measurement of the survival time after supralethal poisoning. Addition of all tested non-oximes increased the therapeutic efficacy of atropine in combination with an oxime against sarin poisoning; however, the differences were not significant. The non-oximes also positively influenced the number of surviving mice 6 h after supralethal poisoning with sarin. In the case of cyclosarin, they were also slightly beneficial in the treatment of acute poisoning. The higher dose of MB444 was able to significantly increase the therapeutic efficacy of standard antidotal treatment of poisoning with cyclosarin. The benefit of each bispyridinium non-oxime compound itself was obviously dose-dependent. In summary, the addition of MB compounds to the standard antidotal treatment of acute nerve agent poisoning was beneficial for the antidotal treatment of sarin or cyclosarin poisoning, although their benefit at 24 h after poisoning was not significant, with the exception of the higher dose of MB444 against cyclosarin.

Evaluation of the Influence of Three Newly Developed Bispyridinium Anti-nicotinic Compounds (MB408, MB442, MB444) on the Efficacy of Antidotal Treatment of Nerve Agent Poisoning in Mice.

The influence of three newly developed bispyridinium antinicotinic compounds (the non-oximes MB408, MB442 and MB444) on the therapeutic efficacy of a standard antidotal treatment (atropine in combination with an oxime) of acute poisoning by the organophosphorus nerve agents tabun and soman was studied in mice. The therapeutic efficacy of atropine in combination with an oxime with or without one of the bispyridinium non-oximes was evaluated by determination of the LD50 values of the nerve agents and measurement of the survival time after supralethal poisoning. Addition of all the tested non-oximes increased significantly the therapeutic efficacy of atropine in combination with an oxime against tabun poisoning. They also positively influenced the number of surviving mice 6 hr after supralethal poisoning with tabun. However, they were only slightly effective for the treatment of soman poisoning. The benefit of the tested bispyridinium non-oximes was dose-dependent. To conclude, the addition of bispyridinium non-oximes to the standard antidotal treatment of acute poisoning with tabun was beneficial regardless of the chosen non-oxime, but only slightly beneficial in the case of soman poisoning.

Do interventions with staff in long-term residential facilities improve quality of care or quality for life people with dementia? A systematic review of the evidence.

BACKGROUND: Common sense suggests and research indicates relationships between staff factors in residential dementia care and quality of life (QOL) for residents, with poor care increasing suffering. However, we do not have a coherent picture of which staff interventions have an impact on quality of care (QOC) or resident QOL. METHODS: A comprehensive search of 20 years' peer-reviewed literature using Medline, PsycINFO, Embase, PubMed, CINAHL, and the Cochrane, Campbell Collaboration identified 4,760 studies meriting full text review. Forty-six met the inclusion criteria, namely interventions in long-term facilities helping staff develop their capacity to provide better care and/or QOL for residents with dementia. Thirty-five other papers comprised an associated predictor review. RESULTS: Conclusions from these limited data are further compromised because nine studies failed to measure effects on residents and only half assessed effects after the project team withdrew. Of these, excellent studies produced change over the medium (3-4 months) or longer term, including reduction in challenging behavior and restraint use but this applied only to a minority. A number of studies failed to measure effects on QOC, limiting conclusions about mechanisms underlying change. CONCLUSION: In general, level of intervention required depended on the target. For outcomes like restraint use, structured education sessions with some support appear adequate. Programs to reduce pain require more support. For complicated issues like challenging behavior and increasing co-operation in showering, detailed, supportive, on-site interventions are required. Improvements in restraint and staff/resident interactions were the most promising findings. (Review registration number: PROSPERO 2014:CRD42014015224).

Evaluation of the benefit of the bispyridinium compound MB327 for the antidotal treatment of nerve agent-poisoned mice.

The potency of the bispyridinium non-oxime compound MB327 [1,1'-(propane-1,3-diyl)bis(4-tert-butylpyridinium) diiodide] to increase the therapeutic efficacy of the standard antidotal treatment (atropine in combination with an oxime) of acute poisoning with organophosphorus nerve agents was studied in vivo. The therapeutic efficacy of atropine alone - or atropine in combination with an oxime, MB327, or both an oxime and MB237 - was evaluated by the determination of LD50 values of several nerve agents (tabun, sarin and soman) in mice with and without treatment. The addition of MB327 increased the therapeutic efficacy of atropine alone, and atropine in combination with an oxime, against all three nerve agents, although differences in the LD50 values only reached statistical significance for sarin. In conclusion, the addition of the compound MB327 to the standard antidotal treatment of acute poisonings with nerve agents was beneficial regardless of the chemical structure of the nerve agent, although at the dose employed, MB327 in combination with atropine, or atropine and an oxime, provided only a modest increase in protection ratio. These results from mice, and previous ones from guinea-pigs, provide consistent evidence for additional, albeit modest, efficacy resulting from the inclusion of the antinicotinic compound MB327 in standard antidotal therapy. Given the typically steep probit slope for the dose-lethality relationship for nerve agents, such modest increases in protection ratio could provide significant survival benefit.

How do staff influence the quality of long-term dementia care and the lives of residents? A systematic review of the evidence.

BACKGROUND: Research suggests and common sense indicates that there are relationships between staff variables in residential dementia care and the quality of life (QOL) of residents, with poor care due to staff factors increasing resident suffering. Despite these indications, we do not have a coherent picture of these relationships, which variables are important, and where to intervene in order to minimize suffering for people with dementia. METHODS: This systematic review examined associations between staff variables, quality of care (QOC), and QOL for residents, using published peer-reviewed literature from the last 20 years. A comprehensive search was conducted using an exhaustive list of search terms, leading to the identification of 33,204 unique papers, which was reduced to 35 on-topic papers. RESULTS: In the main, we were able to provide collective evidence to suggest there are relationships between potentially adjustable staff variables and QOC on to QOL. When staff treat and interact empathetically and humanely in care, there is a relationship with better mood for residents, delayed functional dependence and better food intake. Where staff are more skilled and educated, there is less psychotropic medication use. Unlimited empathy about the risk of residents falling or being in pain is not enough; staff need to know about the dangers of restraint. CONCLUSIONS: Confidence in these indicative links is weakened by a lack of high-quality prospective longitudinal studies focusing on potentially adjustable staff variables, with a bias towards cross-sectional studies including only variables that are fixed or unlikely to change. (Review registration no. PROSPERO 2014:CRD42014015224).

The Development of the strain in dementia care scale (SDCS).

BACKGROUND: Though many staff gain satisfaction from working with people with dementia in residential facilities, they also experience significant stress. This is a serious issue because this in turn can affect the quality of care. There is, however, a lack of instruments to measure staff strain in the dementia-specific residential care environment, and the aim of this study, accordingly, was to develop the "Strain in Dementia Care Scale." METHODS: The instrument was developed in three steps. In the first step, items were derived from six focus group discussions with 35 nurses in the United Kingdom, Australia, and Sweden concerning their experience of strain. In the second step, a preliminary 64-item scale was distributed to 927 dementia care staff in Australia and Sweden, which, based on exploratory factor analysis, resulted in a 29-item scale. In the final step, the 29-item scale was distributed to a new sample of 346 staff in Sweden, and the results were subjected to confirmatory factor analysis. RESULTS: The final scale comprised the following 27 items producing a five-factor solution: Frustrated empathy; difficulties understanding and interpreting; balancing competing needs; balancing emotional involvement; and lack of recognition. CONCLUSIONS: The scale can be used (a) as an outcome measurement in residential care intervention studies; (b) to help residential facilities identify interventions needed to improve staff well-being, and, by extension, those they care for; and

Potency of irritation by benzylidenemalononitriles in humans correlates with TRPA1 ion channel activation.

We show that the physiological activity of solid aerosolized benzylidenemalononitriles (BMNs) including 'tear gas' (CS) in historic human volunteer trials correlates with activation of the human transient receptor potential ankyrin 1 ion channel (hTRPA1). This suggests that the irritation caused by the most potent of these compounds results from activation of this channel. We prepared 50 BMNs and measured their hTRPA1 agonist potencies. A mechanism of action consistent with their physiological activity, involving their dissolution in water on contaminated body surfaces, cell membrane penetration and reversible thiolation by a cysteine residue of hTRPA1, supported by data from nuclear magnetic resonance experiments with a model thiol, explains the structure-activity relationships. The correlation provides evidence that hTRPA1 is a receptor for irritants on nociceptive neurons involved in pain perception; thus, its activation in the eye, nose, mouth and skin would explain the symptoms of lachrymation, sneezing, coughing and stinging, respectively. The structure-activity results and the use of the BMNs as pharmacological tools in future by other researchers may contribute to a better understanding of the TRPA1 channel in humans (and other animals) and help facilitate the discovery of treatments for human diseases involving this receptor.

Strain in nursing care of people with dementia: nurses' experience in Australia, Sweden and United Kingdom.

OBJECTIVES: The aim of this study was to explore nurses' experience of strain in dementia care. METHOD: Focus groups were held with 35 nurses in Sweden, Australia and UK, who care for people with dementia. The discussions were tape-recorded and analysed using qualitative content analysis. RESULTS: The nurses described the complexity of their situation and referred to environmental factors such as 'the system', community attitudes, other staff, residents' family members and also their own family. With regard to caring for people with dementia, three main sources of strain could be identified: Being unable to reach; Trying to protect; and Having to balance competing needs. CONCLUSION: The nurses' experience could be understood as a desire to do the best for the people in their care by trying to alleviate their suffering and enhance their quality of life. When they did not have the resources, opportunity or ability to do this, it caused strain.

P-selectin blocking potency of multimeric tyrosine sulfates in vitro and in vivo.

P-selectin blocking potency was investigated using synthetic monomeric and polymeric anionic compounds containing sulfate groups such as O-sulfotyrosine (sTyr) and/or sulfated Lewis structures. A non-carbohydrate-containing polyacrylamide conjugate sTyr-PAA (80% mol of sTyr) was a remarkably potent inhibitor of P-selectin binding in vitro, having an IC(50) value of 6 ng/mL (equivalent to 10 nM calculated on the basis of sTyr residues or 0.1 nM calculated by the mass of the macromolecule). The inhibitory effect of sTyr-PAA (80%) towards P-selectin is significantly greater than that of fucoidan (IC(50), 100 ng/mL). However, sTyr-PAA (80%) was less effective than fucoidan at reducing neutrophil extravasation in an in vivo rat model of peritonitis.