Abstract We review studies on the pharmacology and mode of action of pyrantel and comment on its ... more Abstract We review studies on the pharmacology and mode of action of pyrantel and comment on its analogs, oxantel and morantel, where appropriate. Pyrantel is a fairly selective agonist of nematode nicotinic acetylcholine receptors (nAChRs). Pyrantel produces depolarization and contraction of nematode body muscle which causes spastic paralysis; it is a relatively potent agonist (EC50~10 µM) on levamisole receptor subtypes of nematode nAChRs. In addition, pyrantel has open-channel blocking effects which reduce the response at higher agonist concentrations, weak anticholinesterase effects, and nicotinic agonist effects at higher concentrations in vertebrate tissues; pyrantel causes spastic paralysis in chicks, contracts the frog rectus abdominis muscle, depolarizes the end-plate potential in the rat hemi-diaphragm, and causes depolarization and then neuromuscular block in the cat soleus and tibialis muscle preparations. Pyrantel selectively activates a subgroup of nematode nAChRs and at toxic doses has effects on host nAChRs.
Secretome data from the non-parasitic free-living nematode Caenorhabditis elegans (N2 strain, L4 ... more Secretome data from the non-parasitic free-living nematode Caenorhabditis elegans (N2 strain, L4 – young adult stage worms) produced by liquid chromatography, tandem mass spectrometry. This data was generated at Génome Québec (QC, Canada) in 2011. Worms were synchronized on agar plates, washed extensively, and incubated in M9 buffer for 4 h. The collected excretory/secretory proteins were separated by SDS-PAGE on a 7–15% gradient acrylamide gel, and stained with Coomassie Brilliant Blue G. The entire lane was subjected to automated band excision to generate 13 contiguous bands which were subjected to reduction, cysteine-alkylation, and in-gel tryptic digestion. MS/MS raw data (Q-TOF micro (Waters Micromass, Manchester, UK)) were transferred from the Q-TOF Microcomputer to a server and automatically manipulated for generation of peaklists (MGF files) by employing Distiller version 2.3.2.0 (http://www.matrixscience.com/distiller.html) with peak picking parameters set at 5 for Signal Noise Ratio (SNR) and at 0.4 for Correlation Threshold (CT). Briefly, MS/MS peak lists (MGF files) generated were analyzed using Mascot (Matrix Science, London, UK) and X! Tandem (Version: 2007.01.01.1) , generating the .dat output files.
Great progress has been made in the development and deployment of medicines to treat parasitic in... more Great progress has been made in the development and deployment of medicines to treat parasitic infections and infestations of humans. In many case, these advances are the basis for hope of elimination or eradication of these diseases. Significant gaps in chemotherapy remain for some infections, but the current landscape of antiparasitic drug therapy is highly encouraging.
Metazoan parasites, especially nematodes, are a highly diverse group of large organisms that typi... more Metazoan parasites, especially nematodes, are a highly diverse group of large organisms that typically sustain an infection for long periods of time with relatively modest pathology. This state is achieved by the release of parasite-derived immunomodulatory molecules which coerce the host into providing a relatively safe niche in which the parasite is able to carry out the host-housed aspects of its life cycle. It has recently been recognized that parasitic nematodes release microRNAs (miRNAs) in culture and in mammalian hosts, primarily in exosome-like vesicles, and that these parasite-derived miRNAs may target host genes involved in the immune response. This review focused primarily on data from filarial nematodes, which occupy tissue niches in humans and other animals, and provides a perspective on possible biological roles of these molecules and their therapeutic and evolutionary implications.
SummaryAvailable primary structural information suggests that the FMRFamide-related peptides (FaR... more SummaryAvailable primary structural information suggests that the FMRFamide-related peptides (FaRPs) from parasitic and free-living nematodes are different, and that free-living forms may not represent appropriate models for the study of the neurochemistry of parasitic forms in the laboratory. However, here we report the isolation and unequivocal identification of AF2 (originally isolated from the parasite,Ascaris suum) from acidified alcoholic extracts of the free-living species,Panagrellus redivivus. While reverse-phase HPLC analysis of extracts revealed FMRFamide-immunoreactivity to be highly heterogeneous, AF2 was the predominant FMRFamide-immunoreactive peptide present (at least 26 pmol/g wet weight of worms). This peptide was also the major immunoreactant identified by an antiserum raised to the conserved C- terminal hexapeptide amide of mammalian pancreatic polypeptide (PP), which has been used previously to isolate neuropeptide F (NPF). These observations were confirmed by radioimmunoassay and chromatographic fractionation of an acidified alcoholic extract ofA. suumheads. The FMRFamide-related peptides present in a nematode extract may be highly dependent on the extraction medium employed, and these data would suggest that this complement of neuropeptides may not be as different between parasitic and free-living nematodes as initial studies have suggested. Finally, all of the evidence suggests that NPF is not present in nematodes and that the PP-immunoreactant previously demonstrated immunochemically is probably AF2.
1. The physiological effects of two Phe-Met-Arg-Phe-NH2 (FMRFamide)-related neuropeptides isolate... more 1. The physiological effects of two Phe-Met-Arg-Phe-NH2 (FMRFamide)-related neuropeptides isolated from the free-living nematode Panagrellus redivivus, SDPNFLRFamide (PF1) and SADPNFLRFamide (PF2), were examined using neuromuscular preparations from the parasitic nematode Ascaris suum. 2. PF1 and PF2 hyperpolarized muscle membrane and induced sustained flaccid paralysis, independent of external Cl-, in both innervated and denervated preparations. 3. PF1 reversed spastic contractions induced by the cholinomimetic levamisole, elevated K+, or the excitatory nematode FMRFamide-related neuropeptides KNEFIRFamide or KHEYLRFamide. 4. PF1 reversal of levamisole contraction was blocked by pretreatment with agents that interfere with nitric oxide (NO) synthesis (e.g., N-nitro-L-arginine), whereas sodium nitroprusside, which releases NO in solution, mimicked PF1 and PF2. 5. NO synthase activity, monitored by the conversion of [3H]arginine to [3H]citrulline, was twice as abundant in A. suum hypodermis as in muscle, but was not present in reproductive tissue. The relative abundance of NO synthase activity in these tissues was similar to the observed specific binding of [3H]PF1. 6. These results suggest that the inhibitory effects of PF1 and PF2 on nematode somatic muscle are mediated by NO, and that the hypodermis may serve a role in this process analogous to that of the endothelium in vertebrate vasculature.
ABSTRACTContinuous cultivation of Plasmodium falciparum presently requires the nutritionally comp... more ABSTRACTContinuous cultivation of Plasmodium falciparum presently requires the nutritionally complex medium, RPMI 1640. A basal medium of KCl, NaCl, Na2HPO4, Ca(NO3)2, MgSO4, glucose, reduced glutathione, HEPES buffer, hypoxanthine, phenol red (in RPMI 1640 concentrations), and 10% (v/v) exhaustively dialyzed pooled human serum was used to determine which vitamins and amino acids had to be exogenously supplied for continuous cultivation. Supplementation of basal medium with calcium pantothenate, cystine, glutamate, glutamine, isoleucine, methionine, proline, and tyrosine was necessary for continuous growth. This semi‐defined minimal medium supported continuous growth of four isolates of P. falciparum at rates slightly less than those obtained with RPMI 1640. Adding any other vitamin or amino acid did not improve growth. Incorporation of several non‐essential amino acids, particularly phenylalanine and leucine, into proteins was markedly enhanced in the minimal medium compared to RPMI 1640.
Abstract We review studies on the pharmacology and mode of action of pyrantel and comment on its ... more Abstract We review studies on the pharmacology and mode of action of pyrantel and comment on its analogs, oxantel and morantel, where appropriate. Pyrantel is a fairly selective agonist of nematode nicotinic acetylcholine receptors (nAChRs). Pyrantel produces depolarization and contraction of nematode body muscle which causes spastic paralysis; it is a relatively potent agonist (EC50~10 µM) on levamisole receptor subtypes of nematode nAChRs. In addition, pyrantel has open-channel blocking effects which reduce the response at higher agonist concentrations, weak anticholinesterase effects, and nicotinic agonist effects at higher concentrations in vertebrate tissues; pyrantel causes spastic paralysis in chicks, contracts the frog rectus abdominis muscle, depolarizes the end-plate potential in the rat hemi-diaphragm, and causes depolarization and then neuromuscular block in the cat soleus and tibialis muscle preparations. Pyrantel selectively activates a subgroup of nematode nAChRs and at toxic doses has effects on host nAChRs.
Secretome data from the non-parasitic free-living nematode Caenorhabditis elegans (N2 strain, L4 ... more Secretome data from the non-parasitic free-living nematode Caenorhabditis elegans (N2 strain, L4 – young adult stage worms) produced by liquid chromatography, tandem mass spectrometry. This data was generated at Génome Québec (QC, Canada) in 2011. Worms were synchronized on agar plates, washed extensively, and incubated in M9 buffer for 4 h. The collected excretory/secretory proteins were separated by SDS-PAGE on a 7–15% gradient acrylamide gel, and stained with Coomassie Brilliant Blue G. The entire lane was subjected to automated band excision to generate 13 contiguous bands which were subjected to reduction, cysteine-alkylation, and in-gel tryptic digestion. MS/MS raw data (Q-TOF micro (Waters Micromass, Manchester, UK)) were transferred from the Q-TOF Microcomputer to a server and automatically manipulated for generation of peaklists (MGF files) by employing Distiller version 2.3.2.0 (http://www.matrixscience.com/distiller.html) with peak picking parameters set at 5 for Signal Noise Ratio (SNR) and at 0.4 for Correlation Threshold (CT). Briefly, MS/MS peak lists (MGF files) generated were analyzed using Mascot (Matrix Science, London, UK) and X! Tandem (Version: 2007.01.01.1) , generating the .dat output files.
Great progress has been made in the development and deployment of medicines to treat parasitic in... more Great progress has been made in the development and deployment of medicines to treat parasitic infections and infestations of humans. In many case, these advances are the basis for hope of elimination or eradication of these diseases. Significant gaps in chemotherapy remain for some infections, but the current landscape of antiparasitic drug therapy is highly encouraging.
Metazoan parasites, especially nematodes, are a highly diverse group of large organisms that typi... more Metazoan parasites, especially nematodes, are a highly diverse group of large organisms that typically sustain an infection for long periods of time with relatively modest pathology. This state is achieved by the release of parasite-derived immunomodulatory molecules which coerce the host into providing a relatively safe niche in which the parasite is able to carry out the host-housed aspects of its life cycle. It has recently been recognized that parasitic nematodes release microRNAs (miRNAs) in culture and in mammalian hosts, primarily in exosome-like vesicles, and that these parasite-derived miRNAs may target host genes involved in the immune response. This review focused primarily on data from filarial nematodes, which occupy tissue niches in humans and other animals, and provides a perspective on possible biological roles of these molecules and their therapeutic and evolutionary implications.
SummaryAvailable primary structural information suggests that the FMRFamide-related peptides (FaR... more SummaryAvailable primary structural information suggests that the FMRFamide-related peptides (FaRPs) from parasitic and free-living nematodes are different, and that free-living forms may not represent appropriate models for the study of the neurochemistry of parasitic forms in the laboratory. However, here we report the isolation and unequivocal identification of AF2 (originally isolated from the parasite,Ascaris suum) from acidified alcoholic extracts of the free-living species,Panagrellus redivivus. While reverse-phase HPLC analysis of extracts revealed FMRFamide-immunoreactivity to be highly heterogeneous, AF2 was the predominant FMRFamide-immunoreactive peptide present (at least 26 pmol/g wet weight of worms). This peptide was also the major immunoreactant identified by an antiserum raised to the conserved C- terminal hexapeptide amide of mammalian pancreatic polypeptide (PP), which has been used previously to isolate neuropeptide F (NPF). These observations were confirmed by radioimmunoassay and chromatographic fractionation of an acidified alcoholic extract ofA. suumheads. The FMRFamide-related peptides present in a nematode extract may be highly dependent on the extraction medium employed, and these data would suggest that this complement of neuropeptides may not be as different between parasitic and free-living nematodes as initial studies have suggested. Finally, all of the evidence suggests that NPF is not present in nematodes and that the PP-immunoreactant previously demonstrated immunochemically is probably AF2.
1. The physiological effects of two Phe-Met-Arg-Phe-NH2 (FMRFamide)-related neuropeptides isolate... more 1. The physiological effects of two Phe-Met-Arg-Phe-NH2 (FMRFamide)-related neuropeptides isolated from the free-living nematode Panagrellus redivivus, SDPNFLRFamide (PF1) and SADPNFLRFamide (PF2), were examined using neuromuscular preparations from the parasitic nematode Ascaris suum. 2. PF1 and PF2 hyperpolarized muscle membrane and induced sustained flaccid paralysis, independent of external Cl-, in both innervated and denervated preparations. 3. PF1 reversed spastic contractions induced by the cholinomimetic levamisole, elevated K+, or the excitatory nematode FMRFamide-related neuropeptides KNEFIRFamide or KHEYLRFamide. 4. PF1 reversal of levamisole contraction was blocked by pretreatment with agents that interfere with nitric oxide (NO) synthesis (e.g., N-nitro-L-arginine), whereas sodium nitroprusside, which releases NO in solution, mimicked PF1 and PF2. 5. NO synthase activity, monitored by the conversion of [3H]arginine to [3H]citrulline, was twice as abundant in A. suum hypodermis as in muscle, but was not present in reproductive tissue. The relative abundance of NO synthase activity in these tissues was similar to the observed specific binding of [3H]PF1. 6. These results suggest that the inhibitory effects of PF1 and PF2 on nematode somatic muscle are mediated by NO, and that the hypodermis may serve a role in this process analogous to that of the endothelium in vertebrate vasculature.
ABSTRACTContinuous cultivation of Plasmodium falciparum presently requires the nutritionally comp... more ABSTRACTContinuous cultivation of Plasmodium falciparum presently requires the nutritionally complex medium, RPMI 1640. A basal medium of KCl, NaCl, Na2HPO4, Ca(NO3)2, MgSO4, glucose, reduced glutathione, HEPES buffer, hypoxanthine, phenol red (in RPMI 1640 concentrations), and 10% (v/v) exhaustively dialyzed pooled human serum was used to determine which vitamins and amino acids had to be exogenously supplied for continuous cultivation. Supplementation of basal medium with calcium pantothenate, cystine, glutamate, glutamine, isoleucine, methionine, proline, and tyrosine was necessary for continuous growth. This semi‐defined minimal medium supported continuous growth of four isolates of P. falciparum at rates slightly less than those obtained with RPMI 1640. Adding any other vitamin or amino acid did not improve growth. Incorporation of several non‐essential amino acids, particularly phenylalanine and leucine, into proteins was markedly enhanced in the minimal medium compared to RPMI 1640.
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Papers by Timothy Geary