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Zoo Biology 2015We fitted two blue wildebeest (Connochaetes taurinus) with modified versions of the Equivital™ EQ02 wireless monitoring system to evaluate if the device could...
We fitted two blue wildebeest (Connochaetes taurinus) with modified versions of the Equivital™ EQ02 wireless monitoring system to evaluate if the device could accurately measure heart rate and respiration rate in this species whilst anaesthetized as well as whilst fully conscious in captivity. Whilst under anaesthesia, we monitored each animal's heart rate and respiration rate using the Equivital™ biotelemetry belt, a Cardell(®) veterinary monitor and manual measurements. The animals were also administered doxapram hydrochloride (Dopram(®) ) and adrenaline intravenously at different times to stimulate changes in respiration and heart rate, respectively. Once 30 minutes of monitoring was completed, we reversed the anaesthetic and left the animals in captivity for 24 hours whilst wearing the Equivital™ belts. After 24 hr, we repeated the anaesthesia and monitoring as well as the administration of the doxapram hydrochloride and adrenaline. Intraclass Correlation Coefficients (ICC) calculated between all three monitoring methods showed moderate to excellent agreements for heart rate on both days (ICC: 0.73-0.98). ICCs calculated between the three methods for respiration rate showed good to excellent agreement between the Equivital belt and the other two methods (0.82-0.92) with the exception of occasions when only poor to fair agreements were found between the Cardell(®) measurements and manual measurements. Heart rate and respiration rate were also found to increase with motion while animals were in captivity. The results indicate that a modified version of the Equivital™ EQ02 system can be used as a potential biotelemetry device for measuring heart and respiration rate in captive blue wildebeest.
Topics: Animals; Animals, Zoo; Antelopes; Doxapram; Epinephrine; Heart Rate; Reproducibility of Results; Respiratory Rate; Telemetry
PubMed: 25982471
DOI: 10.1002/zoo.21222 -
Molecular Pharmacology Nov 2015Compounds PKTHPP (1-{1-[6-(biphenyl-4-ylcarbonyl)-5,6,7,8-tetrahydropyrido[4,3-d]-pyrimidin-4-yl]piperidin-4-yl}propan-1-one), A1899...
Compounds PKTHPP (1-{1-[6-(biphenyl-4-ylcarbonyl)-5,6,7,8-tetrahydropyrido[4,3-d]-pyrimidin-4-yl]piperidin-4-yl}propan-1-one), A1899 (2''-[(4-methoxybenzoylamino)methyl]biphenyl-2-carboxylic acid 2,4-difluorobenzylamide), and doxapram inhibit TASK-1 (KCNK3) and TASK-3 (KCNK9) tandem pore (K2P) potassium channel function and stimulate breathing. To better understand the molecular mechanism(s) of action of these drugs, we undertook studies to identify amino acid residues in the TASK-3 protein that mediate this inhibition. Guided by homology modeling and molecular docking, we hypothesized that PKTHPP and A1899 bind in the TASK-3 intracellular pore. To test our hypothesis, we mutated each residue in or near the predicted PKTHPP and A1899 binding site (residues 118-128 and 228-248), individually, to a negatively charged aspartate. We quantified each mutation's effect on TASK-3 potassium channel concentration response to PKTHPP. Studies were conducted on TASK-3 transiently expressed in Fischer rat thyroid epithelial monolayers; channel function was measured in an Ussing chamber. TASK-3 pore mutations at residues 122 (L122D, E, or K) and 236 (G236D) caused the IC50 of PKTHPP to increase more than 1000-fold. TASK-3 mutants L122D, G236D, L239D, and V242D were resistant to block by PKTHPP, A1899, and doxapram. Our data are consistent with a model in which breathing stimulant compounds PKTHPP, A1899, and doxapram inhibit TASK-3 function by binding at a common site within the channel intracellular pore region, although binding outside the channel pore cannot yet be excluded.
Topics: Amino Acid Sequence; Animals; Benzamides; Benzeneacetamides; Binding Sites; Cells, Cultured; Doxapram; Molecular Docking Simulation; Molecular Sequence Data; Mutagenesis; Potassium Channels, Tandem Pore Domain; Rats; Rats, Inbred F344; Respiratory System Agents; Structure-Activity Relationship
PubMed: 26268529
DOI: 10.1124/mol.115.100107 -
Antimicrobial Agents and Chemotherapy Jun 2016Antibiotic resistance in medically relevant bacterial pathogens, coupled with a paucity of novel antimicrobial discoveries, represents a pressing global crisis....
Antibiotic resistance in medically relevant bacterial pathogens, coupled with a paucity of novel antimicrobial discoveries, represents a pressing global crisis. Traditional drug discovery is an inefficient and costly process; however, systematic screening of Food and Drug Administration (FDA)-approved therapeutics for other indications in humans offers a rapid alternative approach. In this study, we screened a library of 780 FDA-approved drugs to identify molecules that rendered RAW 264.7 murine macrophages resistant to cytotoxicity induced by the highly virulent Yersinia pestis CO92 strain. Of these compounds, we identified 94 not classified as antibiotics as being effective at preventing Y. pestis-induced cytotoxicity. A total of 17 prioritized drugs, based on efficacy in in vitro screens, were chosen for further evaluation in a murine model of pneumonic plague to delineate if in vitro efficacy could be translated in vivo Three drugs, doxapram (DXP), amoxapine (AXPN), and trifluoperazine (TFP), increased animal survivability despite not exhibiting any direct bacteriostatic or bactericidal effect on Y. pestis and having no modulating effect on crucial Y. pestis virulence factors. These findings suggested that DXP, AXPN, and TFP may modulate host cell pathways necessary for disease pathogenesis. Finally, to further assess the broad applicability of drugs identified from in vitro screens, the therapeutic potential of TFP, the most efficacious drug in vivo, was evaluated in murine models of Salmonella enterica serovar Typhimurium and Clostridium difficile infections. In both models, TFP treatment resulted in increased survivability of infected animals. Taken together, these results demonstrate the broad applicability and potential use of nonantibiotic FDA-approved drugs to combat respiratory and gastrointestinal bacterial pathogens.
Topics: Amoxapine; Animals; Anti-Inflammatory Agents, Non-Steroidal; Cell Survival; Clostridioides difficile; Disease Models, Animal; Doxapram; Drug Administration Schedule; Drug Repositioning; Enterocolitis, Pseudomembranous; Female; High-Throughput Screening Assays; Macrophages; Mice; Plague; Prescription Drugs; Salmonella Infections; Salmonella typhimurium; Small Molecule Libraries; Survival Analysis; Trifluoperazine; Yersinia pestis
PubMed: 27067323
DOI: 10.1128/AAC.00326-16 -
Journal of Neurophysiology Apr 2019Doxapram is a respiratory stimulant used for decades as a treatment option in apnea of prematurity refractory to methylxanthine treatment. Its mode of action, however,...
Doxapram is a respiratory stimulant used for decades as a treatment option in apnea of prematurity refractory to methylxanthine treatment. Its mode of action, however, is still poorly understood. We investigated direct effects of doxapram on the pre-Bötzinger complex (PreBötC) and on a downstream motor output system, the hypoglossal nucleus (XII), in the transverse brainstem slice preparation. While doxapram has only a modest stimulatory effect on frequency of activity generated within the PreBötC, a much more robust increase in the amplitude of population activity in the subsequent motor output generated in the XII was observed. In whole cell patch-clamp recordings of PreBötC and XII neurons, we confirmed significantly increased firing of evoked action potentials in XII neurons in the presence of doxapram, while PreBötC neurons showed no significant alteration in firing properties. Interestingly, the amplitude of activity in the motor output was not increased in the presence of doxapram compared with control conditions during hypoxia. We conclude that part of the stimulatory effects of doxapram is caused by direct input on brainstem centers with differential effects on the rhythm generating kernel (PreBötC) and the downstream motor output (XII). NEW & NOTEWORTHY The clinically used respiratory stimulant doxapram has distinct effects on the rhythm generating kernel (pre-Bötzinger complex) and motor output centers (nucleus hypoglossus). These effects are obliterated during hypoxia and are mediated by distinct changes in the intrinsic properties of neurons of the nucleus hypoglossus and synaptic transmission received by pre-Bötzinger complex neurons.
Topics: Action Potentials; Animals; Brain Stem; Central Nervous System Stimulants; Central Pattern Generators; Doxapram; Female; Hypoglossal Nerve; Male; Mice; Motor Neurons; Respiration; Respiratory System Agents
PubMed: 30699003
DOI: 10.1152/jn.00304.2018 -
International Journal of Molecular... Dec 2022Bacterial septicemia is commonly induced by Gram-negative bacteria. The immune response is triggered in part by the secretion of bacterial endotoxin lipopolysaccharide...
Bacterial septicemia is commonly induced by Gram-negative bacteria. The immune response is triggered in part by the secretion of bacterial endotoxin lipopolysaccharide (LPS). LPS induces the subsequent release of inflammatory cytokines which can result in pathological conditions. There is no known blocker to the receptors of LPS. The larval muscle is an amendable model to rapidly screen various compounds that affect membrane potential and synaptic transmission such as LPS. LPS induces a rapid hyperpolarization in the body wall muscles and depolarization of motor neurons. These actions are blocked by the compound doxapram (10 mM), which is known to inhibit a subtype of the two-P-domain K+ channel (K2P channels). However, the K2P channel blocker PK-THPP had no effect on the larval muscle at 1 and 10 mM. These channels are activated by chloroform, which also induces a rapid hyperpolarization of these muscles, but the channels are not blocked by doxapram. Likewise, chloroform does not block the depolarization induced by doxapram. LPS blocks the postsynaptic glutamate receptors on muscle. Pre-exposure to doxapram reduces the LPS block of these ionotropic glutamate receptors. Given that the larval body wall muscles are depolarized by doxapram and hyperpolarized by chloroform, they offer a model to begin pharmacological profiling of the K2P subtype channels with the potential of identifying blockers for the receptors to mitigate the actions of the Gram-negative endotoxin LPS.
Topics: Animals; Doxapram; Lipopolysaccharides; Chloroform; Synaptic Transmission; Drosophila
PubMed: 36555429
DOI: 10.3390/ijms232415787 -
European Journal of Pharmacology Jun 2016The present study was undertaken to investigate whether doxapram, a blocker of tandem pore K(+) (TASK-1/-3) channels, is a useful tool for recovery from morphine-induced...
The present study was undertaken to investigate whether doxapram, a blocker of tandem pore K(+) (TASK-1/-3) channels, is a useful tool for recovery from morphine-induced ventilatory disturbances. Spontaneous ventilation and the hind leg withdrawal response against noxious thermal stimulation were recorded simultaneously in anesthetized rats. Morphine (1.0mg/kg, i.v.) decreased the minute volume resulting from depression of the ventilatory rate and tracheal airflow. Concomitantly, it prolonged the latency of withdrawal response against the thermal stimulation. Subsequent intravenous injection of doxapram recovered the morphine-induced ventilatory depression. This effect of doxapram declined rapidly after a single injection (1.0-3.0mg/kg, i.v.) but persisted with a continuous infusion (0.33mg/kg/min). Neither single injection nor continuous infusion of doxapram had any detectable effect on the analgesic potency of morphine. The central respiratory activity was recorded from the phrenic nerve in anesthetized, vagotomized, paralyzed and artificially ventilated rats. Morphine (3.0mg/kg, i.v.) induced respiratory depression, characterized by a prolonged plateau-like inspiratory discharge (apneustic discharge) in the phrenic nerve. Doxapram (10mg/kg, i.v.) restored the morphine-induced apneustic discharge to an augmenting inspiratory discharge. This study demonstrated that doxapram counteracted morphine-induced respiratory depression by stimulating the central respiratory network without compromising morphine antinociception. These results support the clinical use of doxapram for amelioration of ventilatory disturbances in patients treated with opioids.
Topics: Anesthesia; Animals; Doxapram; Male; Morphine; Phrenic Nerve; Rats; Rats, Wistar; Respiratory Insufficiency
PubMed: 27038521
DOI: 10.1016/j.ejphar.2016.03.053 -
Zebrafish Dec 2017Considering the conserved nature of synaptic physiology among vertebrates, we tested the effects of three psychotropics (diazepam, doxapram, and nicotine) on...
Considering the conserved nature of synaptic physiology among vertebrates, we tested the effects of three psychotropics (diazepam, doxapram, and nicotine) on Microsternarchus cf. bilineatus, measuring 10 parameters associated to the electric organ discharges rhythm and waveform before and after the administration of each drug and a control group. There were statistically significant differences (p < 0.005) among all the experimental groups, F (70, 22619.25) = 77.7, between the two experimental phases within their respective drug treatment, F (80, 24604.51) = 16.0, and among the six experimental hours within their respective phases and groups, F (320, 37124.15) = 4.1. We observed a common general trend of reduction in the electric organ's (EO) firing rate, regardless of the expected stimulant or depressor effect of the drugs on the central nervous system (CNS). The intensity of the response changed with the treatment. The observed changes in the fishes' behavior may be a result of the drugs' direct action on the CNS or a combination of this with systemic effects of each substance tested, also in the EO.
Topics: Animals; Anticonvulsants; Behavior, Animal; Central Nervous System; Central Nervous System Stimulants; Diazepam; Doxapram; Electric Organ; Gymnotiformes; Nicotine; Nicotinic Agonists
PubMed: 28968184
DOI: 10.1089/zeb.2017.1459 -
Journal of the American Association For... Mar 2016Improving the quality of physiologic data collected from research animals is most easily accomplished by collecting as much information as possible from a single...
Improving the quality of physiologic data collected from research animals is most easily accomplished by collecting as much information as possible from a single subject, thereby reducing animal use and error associated with satellite groups. We investigated the feasibility of using a large-animal implantable telemetry device in New Zealand white rabbits (n = 6). The first task was to develop an implantation technique that yielded calibrated tidal volume (Vt) measurements that were within 10% of those obtained simultaneously from a pneumotachograph, a low-noise electrocardiogram, and stable blood pressure. The second task was to challenge implanted rabbits with the respiratory stimulant doxapram to assess linearity of the calibration across a range of Vt. Of the 3 electrode placements attempted, only one resulted in calibrations consistently below 10% error. Optimal electrode placement resulted in calibrated Vt measurements within 1.7% ± 0.3% of those obtained from a pneumotachograph during normal tidal breathing, 7.3% ± 0.7% of those after saline injection, and 6.0% ± 0.5% of those after doxapram injection. The Vt range was 9 to 15 mL for normal tidal breathing and saline injection and 25 to 30 mL after doxapram injection. Increases in mean arterial pressure of 25.0 ± 6.82 mm Hg and decreases in heart rate of 56.3 ± 6.82 bpm were associated with doxapram injection only. Our findings represent the first time that multiple cardiopulmonary endpoints have been assessed by telemetry in conscious, restrained rabbits. Whether animal position affects calibration accuracy warrants investigation.
Topics: Animals; Doxapram; Electric Impedance; Electrocardiography; Heart Rate; Male; Rabbits; Respiratory Function Tests; Respiratory System Agents; Telemetry; Tidal Volume; Toxicity Tests
PubMed: 27025814
DOI: No ID Found -
Frontiers in Bioscience (Landmark... Nov 2023Mutations in the gene are among the most frequent genetic alterations in various cancers, and inhibiting RAS signaling has shown promising results in treating solid...
Identification of Potential Inhibitors Targeting GTPase-Kirsten RAt Sarcoma Virus (K-Ras) Driven Cancers via E-Pharmacophore-Based Virtual Screening and Drug Repurposing Approach.
BACKGROUND
Mutations in the gene are among the most frequent genetic alterations in various cancers, and inhibiting RAS signaling has shown promising results in treating solid tumors. However, finding effective drugs that can bind to the RAS protein remains challenging. This drove us to explore new compounds that could inhibit tumor growth, particularly in cancers that harbor K-Ras mutations.
METHODS
Our study used bioinformatic techniques such as E-pharmacophore virtual screening, molecular simulation, principal component analysis (PCA), extra precision (XP) docking, and ADMET analyses to identify potential inhibitors for K-Ras mutants G12C and G12D.
RESULTS
In our study, we discovered that inhibitors such as afatinib, osimertinib, and hydroxychloroquine strongly inhibit the G12C mutant. Similarly, hydroxyzine, zuclopenthixol, fluphenazine, and doxapram were potent inhibitors for the G12D mutant. Notably, all six of these molecules exhibit a high binding affinity for the H95 cryptic groove present in the mutant structure. These molecules exhibited a unique affinity mechanism at the molecular level, which was further enhanced by hydrophobic interactions. Molecular simulations and PCA revealed the formation of stable complexes within switch regions I and II. This was particularly evident in three complexes: G12C-osimertinib, G12D-fluphenazine, and G12D-zuclopenthixol. Despite the dynamic nature of switches I and II in K-Ras, the interaction of inhibitors remained stable. According to QikProp results, the properties and descriptors of the selected molecules fell within an acceptable range compared to sotorasib.
CONCLUSIONS
We have successfully identified potential inhibitors of the K-Ras protein, laying the groundwork for the development of targeted therapies for cancers driven by K-Ras mutations.
Topics: Humans; Protein Binding; Proto-Oncogene Proteins p21(ras); Pharmacophore; Clopenthixol; Drug Repositioning; Fluphenazine; Early Detection of Cancer; ras Proteins; Neoplasms; Molecular Dynamics Simulation
PubMed: 38062837
DOI: 10.31083/j.fbl2811288 -
BMJ Open Sep 2021Apnoea affects 85% of premature infants under 34 weeks of age and would be an important risk factor for subsequent neuropsychological disorders. Currently, premature...
Protocol of controlled odorant stimulation for reducing apnoeic episodes in premature newborns: a randomised open-label Latin-square study with independent evaluation of the main endpoint (PREMODEUR).
INTRODUCTION
Apnoea affects 85% of premature infants under 34 weeks of age and would be an important risk factor for subsequent neuropsychological disorders. Currently, premature children with life-threatening apnoeas receive stimulants such as methylxanthines (mainly, caffeine) or doxapram (an analeptic unlicensed in children under 15). However, these products have undesirable effects (hyperarousal, irritability, sleep disorders, tachycardia) and are not always effective because apnoea does persist in some premature newborns. Previous studies have indicated that odorant stimulation, a non-invasive intervention, may stimulate the respiratory rhythm. The objective of the present protocol is to reduce the occurrence of apnoeic episodes in premature newborns by controlled odorant stimulation added to current pharmacological treatments.
METHODS AND ANALYSIS
The project is a randomised open-label Latin-square trial with independent evaluation of the main endpoint. It will include 60 preterm neonates from two university hospital neonatal intensive care units over 2 years (2021-2023). Each newborn will receive no (S0), sham (S1) or real olfactory stimulation (S2) in random order. During S2, three distinct odorants (mint, grapefruit and vanilla) will be delivered successively, in puffs, over 24 hours. Mint and grapefruit odours stimulate the main and the trigeminal olfactory pathways, whereas vanilla odour stimulates only the main olfactory pathway. A statistical analysis will compare the incidence of apnoeic episodes during S1 versus S2 using a mixed effects Poisson model.
ETHICS AND DISSEMINATION
Ethical approval was obtained from the Comité de Protection des Personnes Île-de-France XI (# 2017-AO13-50-53). The results will be disseminated through various scientific meetings, specialised peer-reviewed journals and, whenever possible, posted on appropriate public websites.
TRIAL REGISTRATION NUMBER
NCT02851979; Pre-results.
Topics: Apnea; Child; Humans; Infant; Infant, Newborn; Infant, Premature; Infant, Premature, Diseases; Intensive Care Units, Neonatal; Odorants; Randomized Controlled Trials as Topic
PubMed: 34518252
DOI: 10.1136/bmjopen-2020-047141