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The role of collaboration in educating the global pediatric anesthesia workforce. Paediatr Anaesth 2024. [PMID: 38470009 DOI: 10.1111/pan.14877] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/01/2023] [Revised: 02/19/2024] [Accepted: 02/25/2024] [Indexed: 03/13/2024]
Abstract
An estimated 1.7 billion children and adolescents do not have access to safe and affordable surgical care, and the vast majority of these are located in low-middle-income countries (LMICs). Pediatric anesthesia, a specialized field that requires a diverse set of knowledge and skills, has seen various advancements over the years and has become well-established in upper-middle and high-income countries. However, in LMICs, due to a multitude of factors including severe workforce shortages, this has not been the case. Collaborations play a vital role in increasing the capacity of pediatric anesthesiology educators and training the pediatric anesthesia workforce. These efforts directly increase access for children who require surgical intervention. Collaboration models can be operationalized through bidirectional knowledge sharing, training, resource allocation, research and innovation, quality improvement, networking, and advocacy. This article aims to highlight a few of these collaborative efforts. Specifically, the role that the World Federation of Societies of Anaesthesiologists, the Safer Anesthesia from Education program, the Asian Society of Pediatric Anaesthesiologists, Pediatric Anesthesia Training in Africa, the Paediatric Anaesthesia Network New Zealand, the Safe Pediatric Anesthesia Network and two WhatsApp™ groups (global ped anesthesia and the Pediatric Difficult Intubation Collaborative) have played in improving anesthesiology care for children.
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Delivery of Safe Pediatric Anesthesia Care in the First 8000 days: Realities, Challenges, and Solutions in Low- and Middle-Income Countries. World J Surg 2023; 47:3429-3435. [PMID: 37891383 DOI: 10.1007/s00268-023-07229-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/09/2023] [Indexed: 10/29/2023]
Abstract
BACKGROUND Worldwide, perioperative mortality has declined over the past 50 years, but the reduction is skewed toward high-income countries (HICs). Currently, pediatric perioperative mortality is much higher in low- and middle-income countries (LMICs) compared to HICs, despite studied cohorts being predominantly low-risk. These disparities must be studied and addressed. METHODS A narrative review of the literature was undertaken to identify contributing factors and potential knowledge gaps. Interventions aimed at alleviating the outcomes disparities are discussed, and recommendations are made for future directions. RESULTS AND CONCLUSIONS There is a lack of adequately trained pediatric anesthesia providers in LMICs, and the number must be bolstered by making such training available. Essential anesthesia medications and equipment, in pediatric-appropriate sizes, are often not available; neither are essential infrastructure items. Perioperative staff are underprepared for emergent situations that may arise and simulation training may help to ameliorate this. The global anesthesia community has implemented several solutions to address these issues. The World Federation of Societies of Anaesthesiologists (WFSA) and Global Initiative for Children's Surgery have published standards that outline essential items for the provision of safe perioperative pediatric care. Several short educational courses have been developed and introduced in LMICs that either specifically address pediatric patients, or contain a pediatric component. The WFSA also maintains a collection of discrete tutorials for educational purposes. Finally, in Africa, large-scale, prospective data collection is underway to examine pediatric perioperative outcomes. More work needs to be done, though, to improve perioperative outcomes for pediatric patients in LMICs.
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Abstract
BACKGROUND Indicators to evaluate progress towards timely access to safe surgical, anaesthesia, and obstetric (SAO) care were proposed in 2015 by the Lancet Commission on Global Surgery. These aimed to capture access to surgery, surgical workforce, surgical volume, perioperative mortality rate, and catastrophic and impoverishing financial consequences of surgery. Despite being rapidly taken up by practitioners, data points from which to derive the indicators were not defined, limiting comparability across time or settings. We convened global experts to evaluate and explicitly define-for the first time-the indicators to improve comparability and support achievement of 2030 goals to improve access to safe affordable surgical and anaesthesia care globally. METHODS AND FINDINGS The Utstein process for developing and reporting guidelines through a consensus building process was followed. In-person discussions at a 2-day meeting were followed by an iterative process conducted by email and virtual group meetings until consensus was reached. The meeting was held between June 16 to 18, 2019; discussions continued until August 2020. Participants consisted of experts in surgery, anaesthesia, and obstetric care, data science, and health indicators from high-, middle-, and low-income countries. Considering each of the 6 indicators in turn, we refined overarching descriptions and agreed upon data points needed for construction of each indicator at current time (basic data points), and as each evolves over 2 to 5 (intermediate) and >5 year (full) time frames. We removed one of the original 6 indicators (one of 2 financial risk protection indicators was eliminated) and refined descriptions and defined data points required to construct the 5 remaining indicators: geospatial access, workforce, surgical volume, perioperative mortality, and catastrophic expenditure. A strength of the process was the number of people from global institutes and multilateral agencies involved in the collection and reporting of global health metrics; a limitation was the limited number of participants from low- or middle-income countries-who only made up 21% of the total attendees. CONCLUSIONS To track global progress towards timely access to quality SAO care, these indicators-at the basic level-should be implemented universally as soon as possible. Intermediate and full indicator sets should be achieved by all countries over time. Meanwhile, these evolutions can assist in the short term in developing national surgical plans and collecting more detailed data for research studies.
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Factors influencing mothers' decisions regarding obstetrical care in Western Kenya: a mixed-methods study. BMC WOMENS HEALTH 2021; 21:210. [PMID: 34011323 PMCID: PMC8136230 DOI: 10.1186/s12905-021-01355-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/19/2020] [Accepted: 05/11/2021] [Indexed: 11/20/2022]
Abstract
Background Siaya County in Western Kenya has one of the highest maternal mortality rates in Kenya. We sought to elucidate factors that influence mothers’ decisions regarding where to seek obstetrical care, to inform interventions that seek to promote effective use of obstetric services and reduce maternal mortalities. To guide our research, we used the “Three Delays Model”, focusing on the first delay—seeking care. While interventions to reduce maternal mortalities have focused on addressing delays in accessing and receiving care, context-specific data on drivers of the first delay are scarce. Methods We used a mixed-method study to assess how maternal decision-making of birth location is influenced by personal, contextual, and cultural factors. We conducted structured interviews with women aged 14 years or older living in Siaya, Bondo, and Yala, rural districts in Western Kenya. We then conducted focus group interviews with a subset of women to elucidate this question: How do drivers of the first delay (i.e., seeking care) affect the decision to seek home versus hospital delivery, potentially negatively influencing maternal mortality. Results Three hundred and seven women responded to the surveys, and 67 women (22%) from this group participated in focus group interviews. Although we focused on type 1 delays, we discovered that several factors that impact type 2 and type 3 delays directly contribute to type 1 delays. Our findings highlighted that factors influencing women’s decisions to seek care are not simply medical or cultural but rather contextual, involving many elements of life, particularly in rural communities. Conclusions It is imperative to address multiple-level factors that influence women’s decisions to seek care and have in-hospital deliveries. To curtail maternal mortality in rural Western Kenya and comparable settings, targeted interventions must take into consideration these important influencers. Supplementary Information The online version contains supplementary material available at 10.1186/s12905-021-01355-9.
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Global surgery in the 21st century: The voice from Africa - We need a new model. Paediatr Anaesth 2021; 31:510-512. [PMID: 33844377 DOI: 10.1111/pan.14162] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/02/2021] [Revised: 02/15/2021] [Accepted: 02/16/2021] [Indexed: 12/26/2022]
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Development and Pilot Testing of a Context-Relevant Safe Anesthesia Checklist for Cesarean Delivery in East Africa. Anesth Analg 2019; 128:993-998. [DOI: 10.1213/ane.0000000000003874] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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World Health Organization-World Federation of Societies of Anaesthesiologists (WHO-WFSA) International Standards for a Safe Practice of Anesthesia. Anesth Analg 2018; 126:2047-2055. [DOI: 10.1213/ane.0000000000002927] [Citation(s) in RCA: 73] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Molecular characterization of Wilms' tumor from a resource-constrained region of sub-Saharan Africa. Int J Cancer 2012; 131:E983-94. [PMID: 22437966 DOI: 10.1002/ijc.27544] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2011] [Accepted: 03/05/2012] [Indexed: 11/10/2022]
Abstract
Sub-Saharan African children have an increased incidence of Wilms' tumor (WT) and experience alarmingly poor outcomes. Although these outcomes are largely due to inadequate therapy, we hypothesized that WT from this region exhibits features of biological aggressiveness that may warrant broader implementation of high-risk therapeutic protocols. We evaluated 15 Kenyan WT (KWT) for features of aggressive disease (blastemal predominance and Ki67/cellular proliferation) and treatment resistance (anaplasia and p53 immunopositivity). To explore the additional biological features of KWT, we determined the mutational status of the CTNNB1/β-catenin and WT1 genes and performed immunostaining for markers of Wnt pathway activation (β-catenin) and nephronic progenitor cell self-renewal (WT1, CITED1 and SIX2). We characterized the proteome of KWT using imaging mass spectrometry (IMS). The results were compared to histology- and age-matched North American WT (NAWT) controls. For patients with KWT, blastemal predominance was noted in 53.3% and anaplasia in 13%. We detected increased loss to follow-up (p = 0.028), disease relapse (p = 0.044), mortality (p = 0.001) and nuclear unrest (p = 0.001) in patients with KWT compared to controls. KWT and NAWT showed similar Ki67/cellular proliferation. We detected an increased proportion of epithelial nuclear β-catenin in KWT (p = 0.013). All 15 KWT specimens were found to harbor wild-type CTNNB1/β-catenin, and one contained a WT1 nonsense mutation. WT1 was detected by immunostaining in 100% of KWT, CITED1 in 80% and SIX2 in 80%. IMS revealed a molecular signature unique to KWT that was distinct from NAWT. The African WT specimens appear to express markers of adverse clinical behavior and treatment resistance and may require alternative therapies or implementation of high-risk treatment protocols.
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Abstract
We report an extensive program of high-precision radiocarbon dating to establish the best date for a floating 1599-year Anatolian tree ring chronology that spans the later third millennium B.C. through the earlier first millennium B.C. This chronology is directly associated with a number of key sites and ancient personages. A previously suggested dating is withdrawn and is replaced by a robust new date fix 22 (+4 or -7) years earlier. These new radiocarbon wiggle-matched dates offer a unique independent resource for establishing the precise chronology of the ancient Near East and Aegean and help resolve, among others, a long-standing debate in favor of the so-called Middle Mesopotamian chronology.
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Abstract
Radiocarbon dating methods typically assume that there are no significant tropospheric (14)CO(2) gradients within the low- to mid-latitude zone of the Northern Hemisphere. Comparison of tree ring (14)C data from southern Germany and Anatolia supports this assumption in general but also documents episodes of significant short-term regional (14)CO(2) offsets. We suggest that the offset is caused by an enhanced seasonal (14)CO(2) cycle, with seasonally peaked flux of stratospheric (14)C into the troposphere during periods of low solar magnetic activity, coinciding with substantial atmospheric cooling. Short-term episodes of regional (14)CO(2) offsets are important to palaeoclimate studies and to high-resolution archaeological dating.
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Effects of chronic dietary administration of the cholinergic false precursor N-amino-N,N-dimethylaminoethanol on behavior and cholinergic parameters in rats. Brain Res 1986; 373:197-204. [PMID: 3013361 DOI: 10.1016/0006-8993(86)90331-8] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The choline analog, N-amino-N,N-dimethylaminoethanol (NADe), was fed ad libitum (chloride salt; 0.5%) to weanling rats in a low choline, low methionine synthetic diet. Control rats were fed choline chloride (0.5%) in place of NADe. Initial observation and behavioral screen tests of grasp strength, startle reflex, righting reflex, analgesia (hot plate test) and body temperature did not reveal any toxic effects caused by NADe, although both experimental and control groups gained weight more slowly than rats fed standard lab chow. After 25 days on the diet, the performance of rats fed NADe in a one-trial passive avoidance test was significantly impaired compared to control rats. There was no difference between experimental and control rats in sensitivity to foot shock or in activity monitored in a closed field. A subjective, 6-component behavioral rating scale indicated rats fed NADe were resistant to handling but not aggressive. These behavioral results were similar in two separate feeding experiments using deuterium-labeled and unlabeled NADe. The twitch response of isolated rat phrenic nerve-diaphragms during stimulation did not show any impairment of neuromuscular function in rats fed NADe. Receptor binding experiments indicated there were no differences between experimental and control rats in tritiated quinuclidinyl benzilate [( 3H]QNB) binding capacity in cortex, heart and ileum. Competitive [3H]QNB binding with carbachol indicated there was no difference in the IC50's measured in cortex homogenates. Acetylcholinesterase (AChE) and choline acetyltransferase (ChAT) activities in cortex were similar in experimental and control groups.(ABSTRACT TRUNCATED AT 250 WORDS)
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Acetyl-N-aminodeanol: a cholinergic false transmitter in rat phrenic nerve-diaphragm and guinea-pig myenteric plexus preparations. J Pharmacol Exp Ther 1985; 235:147-56. [PMID: 2864431] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
The metabolism of the choline analog N-amino-N,N-dimethylaminoethanol (N-aminodeanol) by isolated rat diaphragm and guinea-pig myenteric plexus preparations and the pharmacological properties of the acetate ester were studied. Deuterium-labeled N-aminodeanol was transported and acetylated by rat diaphragm and guinea-pig myenteric plexus preparations. Diaphragms stimulated indirectly in the presence of [2H4]N-aminodeanol (2 X 10(-5) M) released [2H4]acetyl-N-aminodeanol at 38% the rate at which [2H4]acetylcholine was released from controls incubated with [2H4]choline (2 X 10(-5) M). In the guinea-pig myenteric plexus, [2H4]acetyl-N-aminodeanol was synthesized and released at a rate up to 70% that measured for [2H4] acetylcholine. N-methylatropine (10(-7) M) enhanced the stimulated release of [2H4]acetyl-N-aminodeanol and [2H4] acetylcholine (in separate controls) by the same amount (2,3-fold). After incubation in the presence of [2H4]N-aminodeanol, [2H4]acetyl-N-aminodeanol replaced (mole for mole) 17 and 50% of the endogenous acetylcholine tissue content in diaphragm and myenteric plexus, respectively. As the tissue [2H0]acetylcholine was replaced, its release was reduced to 38 and 22% of control in diaphragm and myenteric plexus, respectively. Combined transmitter release (true + false) was reduced to 56 to 79% of release from controls. Endogenous choline efflux apparently limited the replacement of true with false transmitter in these preparations. Acetyl-N-aminodeanol had 4 and 17% the potency of acetylcholine on the guinea-pig ileum and frog rectus abdominis preparations, respectively. These findings indicate that [2H4]N-aminodeanol forms a false transmitter in rat diaphragm and guinea-pig myenteric plexus and may potentially interfere with cholinergic function. Effective replacement of endogenous acetylcholine in vivo would also require replacement of endogenous sources of choline for transmitter synthesis.
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In vivo metabolism of a cholinergic false precursor after dietary administration to rats. J Pharmacol Exp Ther 1985; 235:157-61. [PMID: 4045719] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
The false cholinergic precursor [2H4]N-amino-N,N-dimethylaminoethanol (N-aminodeanol, NADe) was fed ad libitum to weanling rats in a low choline (Ch), low methionine synthetic diet. The free [2H4]NADe plasma concentration achieved at 32 days was 51 microM. The free Ch plasma concentration was reduced to 6 microM, compared to 20 microM measured in control rats which were fed Ch in place of [2H4]NADe. After 33 days the rats were killed by rapid microwave fixation, and tissues were assayed for [2H4]NADe, [2H0]Ch and their acetate esters using combined gas chromatography mass spectrometry. Approximately 50% of the acetylcholine content of cortex, striatum, hippocampus, diaphragm and ileum had been replaced by the false transmitter [2H4]O-acetyl-N-aminodeanol. In all tissues measured except striatum the sum of the true + false transmitters was not significantly different from the acetylcholine content in control rats. In striatum the sum of the transmitters was significantly reduced to 79% of control. [2H4]NADe was incorporated into lipids. The ratio of lipid bound [2H4]NADe to lipid bound Ch in the plasma of experimental rats was 2.6. In cortex, the ratio of lipid bound [2H4]NADe to lipid bound Ch (1.3) was comparable to the ratio of false to true transmitter (1.0), although the ratio of free [2H4]NADe to free Ch was much higher (4.9). NADe caused no obvious toxicity, although both control and experimental groups gained weight more slowly than rats fed standard laboratory chow. These results demonstrate that NADe can enter the biochemical pathways for Ch in vivo, causing replacement of endogenous acetylcholine with the false transmitter acetyl-NADe.(ABSTRACT TRUNCATED AT 250 WORDS)
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Metabolism and subcellular distribution of N-amino-N,N-dimethylaminoethanol (N-aminodeanol) in rat striatal synaptosomes. J Pharmacol Exp Ther 1985; 235:135-46. [PMID: 4045718] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
The metabolism and subcellular distribution of a novel choline analog, N-amino-N,N-dimethylaminoethanol (N-aminodeanol) in rat striatal synaptosomes was studied using combined gas chromatography mass spectrometry for simultaneous estimation of N-aminodeanol, choline, tracer choline and their acetate esters. The enzymes choline acetyltransferase, acetylcholinesterase and choline kinase were assayed in kinetic studies using N-aminodeanol or acetyl-N-aminodeanol as substrates. The results demonstrate that [2H4]N-aminodeanol is transported and acetylated in synaptosomes at rates approximately 30% of those measured for [2H4]choline. Of the [2H4]N-aminodeanol that was transported by the high affinity choline uptake system, the proportion acetylated was similar to that measured for [2H4]choline. [2H4]Acetyl-N-aminodeanol replaced endogenous acetylcholine stores and was released. The combined release of endogenous and false transmitters from synaptosomes in the presence of [2H4]N-aminodeanol was reduced compared to controls in the presence of [2H4]choline, although combined tissue stores did not change significantly. After coincubation with [2H4]N-aminodeanol and [2H4]choline, the molar ratios of true and false transmitter in the tissue appeared to reflect the kinetic parameters for high affinity transport of the precursors. Subcellular fractionation experiments indicated that [2H4]acetyl-N-aminodeanol was incorporated into vesicles more slowly than [2H4]acetylcholine. These results indicate that the reduced rate of turnover in the presence of false precursor is not due to its rate of acetylation or to the rate of release of previously formed false transmitter, but rather to the slower membrane transport of N-aminodeanol by the high affinity uptake system. The replacement of endogenous acetylcholine in synaptosomes by acetyl-N-aminodeanol, which has 4% the potency of acetylcholine at muscarinic receptors, suggests that N-aminodeanol may be useful in studying the in vivo effects of a false cholinergic transmitter.
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Rapid decline in acetylcholine release and content of rat extensor digitorum longus muscle after denervation. Exp Neurol 1983; 81:613-26. [PMID: 6884472 DOI: 10.1016/0014-4886(83)90330-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
The amount of acetylcholine (ACh) and choline (Ch) in normal and denervated rat extensor digitorum longus (EDL) muscles, as well as that released spontaneously from these muscles, was determined by an extremely sensitive gas chromatographic-mass spectrometric assay method. We found decreases in ACh content and spontaneous, resting ACh release as early as 8 h after denervation. The ACh content decreased to a plateau of 30% of control by 11 h; ACh release attained a plateau of 50% of control several hours later. These results showed that in denervated EDL muscles ACh content and spontaneous release (measured biochemically) decreased before nerve-evoked and spontaneous quantal release (measured physiologically) ceased at most synapses. The rapid reduction in ACh, or possibly in other substances that may be released with ACh, may be an important factor in initiating postsynaptic degenerative changes after nerve transection. Choline content and choline resting release increased significantly at both 1 and 3 days after nerve transection. These increases may be related to onset of postsynaptic neuromuscular degenerative changes.
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Estimation of N-amino-N,N-dimethylaminoethanol, choline and their acetate esters by gas chromatography mass spectrometry. Anal Biochem 1983; 130:88-94. [PMID: 6135371 DOI: 10.1016/0003-2697(83)90653-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
A method is described for measurement of choline, N-aminodeanol, and their acetyl esters by gas chromatography mass spectrometry. The preparation of N-aminodeanol and its isotopic variants is also described. This method allows a thorough quantitative analysis of the replacement of true with false neurotransmitter in biological preparations.
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Abstract
We have investigated the effects of intraventricularly or i.p. administered beta-bungarotoxin on the tissue content of acetylcholine and choline in three vertebrate species. A gas chromatographic mass spectrometric assay was used to measure acetylcholine and choline. Intraventricular administration of beta-bungarotoxin (1 microgram, 105 min) in rats raised the acetylcholine content of hippocampus and striatum but not of cortex. Choline was significantly increased in all three brain regions. Injection of the toxin i.p. (5 micrograms, 90 min) in rats caused variable increases of the acetylcholine content of diaphragm, tongue, temporalis muscle and adrenal gland, but no significant change was seen in heart atrium, eye, ileum or superior cervical ganglion. Significant increases of choline content were seen in heart and adrenal. The toxin caused the same degree of increase of acetylcholine in mouse diaphragm as in the rat. No alteration of sartorius muscle or tongue acetylcholine was observed after i.p. injection of beta-bungarotoxin (5 micrograms) in frog. Results with 125I-labelled beta-bungarotoxin (rats, i.p.) suggest that the observed differences in response to beta-bungarotoxin cannot be accounted for by the distribution of toxin alone. From these data we make suggestions regarding the variable effects of beta-bungarotoxin on tissue acetylcholine and choline content and the implication of these findings for the mechanism of action of the toxin.
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Beta-bungarotoxin stimulates the synthesis and accumulation of acetylcholine in rat phrenic nerve diaphragm preparations. J Physiol 1981; 310:13-35. [PMID: 7230031 PMCID: PMC1274726 DOI: 10.1113/jphysiol.1981.sp013535] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
1. The effects of beta-bungarotoxin on acetylcholine (ACh) synthesis, tissue content and release have been studied in the rat diaphragm. A gas chromatographic mass spectrometric assay was used to measure ACh and choline. 2. Within 30 min, beta-bungarotoxin (0.14 or 1.4 micrograms/ml.) caused a significant increase in tissue ACh content. This increase was apparent prior to the final inhibition by beta-bungarotoxin of evoked (10 Hz) ACh release. 3. The toxin enhanced the incorporation of [2H4]Ch into [2H4]ACh in both resting and stimulated preparations. 4. Hemicholinium-3 blocked the rise in diaphragm ACh normally produced by beta-bungarotoxin. 5. Beta-Bungarotoxin did not directly activate choline acetyltransferase in muscle homogenates. 6. The toxin-induced rise in tissue ACh was largely absent in Ca2+-free solutions which contained either EGTA (1 mM) or SrCl2 (2 or 10 mM). 7. Non-neurotoxic phospholipases A2, fatty acids and the neurotoxic phospholipase A2, notexin, did not cause ACh accumulation in the diaphragm. 8. Beta-Bungarotoxin did not stimulate ACh synthesis in denervated muscle. 9. The extra ACh which accumulated after beta-bungarotoxin did not contribute to enhanced release by nerve impulses even when 4-aminopyridine was added to the medium. High K+ solution and black widow spider venom were also ineffective in increasing output from toxin-treated diaphragms relative to controls that had not been treated with beta-bungarotoxin. 10. Prior injection of a rat with botulinum toxin prevented the accumulation of ACh due to beta-bungarotoxin. Tubocurarine, however, did not antagonize beta-bungarotoxin. 11. These data indicate that beta-bungarotoxin has a unique capacity to inhibit ACh release and stimulate ACh synthesis in diaphragm nerve endings. The results are discussed in terms of a possible action of beta-bungarotoxin to raise the level of ionized Ca in the nerve terminal cytosol.
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