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Diabetes Oct 2023Roux-en-Y gastric bypass (GB) and sleeve gastrectomy (SG) surgeries increase prandial insulin and glucagon secretion but reduce the endogenous glucose production (EGP)...
UNLABELLED
Roux-en-Y gastric bypass (GB) and sleeve gastrectomy (SG) surgeries increase prandial insulin and glucagon secretion but reduce the endogenous glucose production (EGP) response to hypoglycemia in comparison with control subjects who had not undergone gastric surgery (CN), suggesting that parasympathetic nervous system (PNS) plays a role. Here, we investigated the effect of acute PNS blockade on the post-meal counterregulatory response to insulin-induced hypoglycemia in GB and SG compared with CN. Glucose kinetics and islet cell secretion were measured in nine subjects without diabetes with GB and seven with SG and five CN during hyperinsulinemic-hypoglycemic clamp (∼3.2 mmol/L) combined with meal ingestion on two separate days with and without intravenous atropine infusion. Glucose and hormonal levels were similar at baseline and during steady-state hypoglycemia before meal ingestion in three groups and unaffected by atropine. Atropine infusion diminished prandial systemic appearance of ingested glucose (RaO) by 30%, EGP by 40%, and glucagon response to hypoglycemia by 90% in CN. In GB or SG, blocking PNS had no effect on the RaO or meal-induced hyperglucagonemia but increased EGP in SG without any effect in GB (P < 0.05 interaction). These findings indicate that cholinergic signal contributes to the recovery from hypoglycemia by meal consumption in humans. However, bariatric surgery dissipates PNS-mediated physiologic responses to hypoglycemia in the fed state.
ARTICLE HIGHLIGHTS
Rerouted gut after Roux-en-Y gastric bypass (GB) and, to a lesser degree, after sleeve gastrectomy (SG) leads to larger glucose excursion and lower nadir glucose, predisposing individuals to hypoglycemia. Despite prandial hyperglucagonemia, endogenous glucose production response to hypoglycemia is reduced after GB or SG. Parasympathetic nervous system (PNS) activity plays a key role in regulation of glucose kinetics and islet cell function. We examined the effect of acute PNS blockade on counterregulatory glucose and islet cell response to meal ingestion during insulin-induced hypoglycemia among GB, SG, and control subjects who had not had gastric surgery. Our findings demonstrate that cholinergic signal is critical in the recovery from hypoglycemia by meal ingestion in humans who have not had gastric surgery, although prandial PNS-mediated physiologic responses to hypoglycemia are differentially changed by GB and SG.
Topics: Humans; Glucagon; Blood Glucose; Hypoglycemia; Insulin; Bariatric Surgery; Glucose; Gastric Bypass; Atropine; Gastrectomy
PubMed: 37467435
DOI: 10.2337/db23-0207 -
Journal of Education & Teaching in... Jan 2024Emergency medicine residents and medical students on emergency medicine rotation.
AUDIENCE
Emergency medicine residents and medical students on emergency medicine rotation.
BACKGROUND
Calcium channel blocker (CCB) overdoses can be severe with potentially serious adverse outcomes. CCBs work by blocking the calcium channels on smooth and cardiac muscle tissue. At low dose ranges, dihydropyridine CCBs (such as nifedipine, amlodipine, and nicardipine) block the L-type calcium receptors in the peripheral vasculature, whereas non-dihydropyridine CCBs (such as: verapamil and diltiazem) affect the L-type calcium receptors in the myocardium.1 Because of this distinction, dihydropyridine CCB toxicity manifests as arterial vasodilation and non-dihydropyridine CCB toxicity is associated with cardiac manifestations such as bradycardia and negative inotropy.2 It is important to note that in high concentrations (such as in overdoses), CCBs lose specificity for their specific receptors and can show all the manifestations of toxicity such as bradycardia, peripheral vasodilation, and hypotension. Patients can develop both vasoplegic shock from peripheral vasodilation and cardiogenic shock. This is a high acuity low occurrence case with infrequently used but specific treatments, and thus this case provides educational value.
EDUCATIONAL OBJECTIVES
At the end of this oral board session, examinees will: (1) demonstrate ability to evaluate a patient with undifferentiated shock with bradycardia and discuss the differential diagnosis, (2) recognize the signs and symptoms of calcium channel blocker overdose, (3) demonstrate ability to manage treatment of a patient with calcium channel overdose.
EDUCATIONAL METHODS
This oral board case followed the standard American Board of Emergency Medicine-style case in a tertiary care hospital with access to all specialists and resources needed. This case was tested using 12 resident volunteers ranging from PGY 1-2 in an ACGME (Accreditation Council for Graduate Medical Education) accredited emergency medicine residency program.
RESEARCH METHODS
Immediate feedback was solicited both from the learners and from the evaluators following the debriefing session. Residents were asked to evaluate the educational value of the case using a 1-5 Likert scale (5 being excellent). Evaluators were asked to score the residents using the ACGME core competencies with a scale of 1-8, 1-4 being unacceptable and 5-8 being acceptable.
RESULTS
Seven PGY1 residents and five PGY2 residents, thus twelve residents in total, completed the case. The average score was 5.10/8. Three residents missed zero critical actions. The most common critical action missed was consulting cardiology or cardiothoracic surgery for circulatory support options. Many residents failed to recognize that the patient did not have a perfusing blood pressure at the beginning of the case and did not start CPR. Although most residents recognized the patient's hemodynamic collapse was from a calcium channel blocker overdose, most did not know the treatment for this beyond atropine and intravenous fluids.The learners rated the educational value of the case as 4.9/5. Seven residents reported that the case definitely increased their medical knowledge; five residents reported that it somewhat increased their medical knowledge. All residents rated the case as helpful in preparing to manage this medical condition.
DISCUSSION
The educational content from this case was effective. This is a high acuity low occurrence case that has unique treatments that are not commonly used. This makes this case excellent for practice and discussion. We learned during implementation that this case has a high degree of difficulty compared to other cases, and junior learners will need more prompting. It is also important for the proctor to keep the case moving because there is a lot to cover in the allotted amount of time.
TOPICS
Calcium channel blocker overdose, toxicology.
PubMed: 38344049
DOI: 10.21980/J8CQ07 -
Clinical & Experimental Ophthalmology Jul 2024A rebound in myopia progression following cessation of atropine eyedrops has been reported, yet there is limited data on the effects of stopping 0.01% atropine compared... (Randomized Controlled Trial)
Randomized Controlled Trial
BACKGROUND
A rebound in myopia progression following cessation of atropine eyedrops has been reported, yet there is limited data on the effects of stopping 0.01% atropine compared to placebo control. This study tested the hypothesis that there is minimal rebound myopia progression after cessation of 0.01% atropine eyedrops, compared to a placebo.
METHODS
Children with myopia (n = 153) were randomised to receive 0.01% atropine eyedrops or a placebo (2:1 ratio) daily at bedtime during the 2-year treatment phase of the study. In the third year (wash-out phase), all participants ceased eyedrop instillation. Participants underwent an eye examination every 6 months, including measurements of spherical equivalent (SphE) after cycloplegia and axial length (AL). Changes in the SphE and AL during the wash-out phase and throughout the 3 years of the study (treatment + wash-out phase) were compared between the treatment and control groups.
RESULTS
During the 1-year wash-out phase, SphE and AL progressed by -0.41D (95% CI = -0.33 to -0.22) and +0.20 mm (95% CI = -0.46 to -0.36) in the treatment group compared to -0.28D (95% CI = 0.11 to 0.16) and +0.13 mm (95% CI = 0.18 to 0.21) in the control group. Progression in the treatment group was significantly faster than in the control group (p = 0.016 for SphE and <0.001 for AL). Over the 3-year study period, the cumulative myopia progression was similar between the atropine and the control groups.
CONCLUSIONS
These findings showed evidence of rapid myopia progression following cessation of 0.01% atropine. Further investigations are warranted to ascertain the long-term effects of atropine eyedrops.
Topics: Humans; Atropine; Disease Progression; Male; Female; Child; Ophthalmic Solutions; Mydriatics; Refraction, Ocular; Double-Blind Method; Axial Length, Eye; Myopia; Western Australia; Adolescent
PubMed: 38400607
DOI: 10.1111/ceo.14368 -
The Journal of Innovations in Cardiac... Dec 2023Pulmonary vein isolation via cryoballoon (CB) ablation is the cornerstone ablation strategy for the treatment of atrial fibrillation (AF). Acute intraprocedural...
Pulmonary vein isolation via cryoballoon (CB) ablation is the cornerstone ablation strategy for the treatment of atrial fibrillation (AF). Acute intraprocedural hypotensive and/or bradycardic responses have been reported in patients undergoing CB ablation for AF. However, it remains unclear as to whether these are due to a true vagal response (VR), which can be used to predict long-term outcomes of CB ablation. We analyzed 139 freezes across 17 patients who received CB ablation for paroxysmal AF, measuring vital signs and freeze characteristics. Only one freeze was associated with both hypotension and bradycardia, constituting a true VR. Several freezes were associated with hypotension only that did not respond to atropine administration, suggesting that these responses are not associated with a VR. Hypotensive responses were significantly associated with ice bubble bursts during CB deflation. Unlike the true VR reported in patients undergoing conscious sedation, the presence of acute hypotension shortly after CB deflation cannot be used as a predictor for long-term ablation outcomes.
PubMed: 38155725
DOI: 10.19102/icrm.2023.14123 -
Veterinary Medicine and Science Sep 2023A 6-year-old neutered male Siamese cat was referred for investigation of hindlimb ataxia and blindness of 2 weeks' duration. A swollen right hind limb, with no history...
A 6-year-old neutered male Siamese cat was referred for investigation of hindlimb ataxia and blindness of 2 weeks' duration. A swollen right hind limb, with no history of trauma, and no evidence of an external wound, was observed on physical examination. Ophthalmic examination revealed bilateral absence of the menace response and changes consistent with uveitis. Blood tests identified changes consistent with inflammation including serum amyloid A elevation. Infectious disease testing was negative. Degenerate neutrophils and bacterial cocci were detected on fine needle aspiration cytology of the affected limb. Thoracic radiography and abdominal ultrasonography identified no abnormalities. Primary pyomyositis was suspected and clindamycin was prescribed following Penrose drain tube placement. In addition, eye drops containing tobramycin, atropine, and prednisolone were administered. The clinical signs and serum amyloid A level were markedly improved after 5 days of treatment. Based on the medical history and lack of other findings, the uveitis was suspected to be secondary to the pyomyositis. The clinical signs resolved completely, and no recurrence was reported within a 6-month follow-up period. To the best of our knowledge, primary pyomyositis with uveitis has not been previously reported in cats.
Topics: Cats; Male; Animals; Pyomyositis; Serum Amyloid A Protein; Uveitis; Cat Diseases
PubMed: 37515576
DOI: 10.1002/vms3.1224 -
Planta Medica May 2024Plants are an incredible source of metabolites showing a wide range of biological activities. Among these, there are the alkaloids, which have been exploited for medical... (Review)
Review
Plants are an incredible source of metabolites showing a wide range of biological activities. Among these, there are the alkaloids, which have been exploited for medical purposes since ancient times. Nowadays, many plant-derived alkaloids are the main components of drugs used as therapy for different human diseases. This review deals with providing an overview of the alkaloids used to treat eye diseases, describing the historical outline, the plants from which they are extracted, and the clinical and molecular data supporting their therapeutic activity. Among the different alkaloids that have found application in medicine so far, atropine and pilocarpine are the most characterized ones. Conversely, caffeine and berberine have been proposed for the treatment of different eye disorders, but further studies are still necessary to fully understand their clinical value. Lastly, the alkaloid used for managing hypertension, reserpine, has been recently identified as a potential drug for ameliorating retinal disorders. Other important aspects discussed in this review are different solutions for alkaloid production. Given that the industrial production of many of the plant-derived alkaloids still relies on extraction from plants, and the chemical synthesis can be highly expensive and poorly efficient, alternative methods need to be found. Biotechnologies offer a multitude of possibilities to overcome these issues, spanning from genetic engineering to synthetic biology for microorganisms and bioreactors for plant cell cultures. However, further efforts are needed to completely satisfy the pharmaceutical demand.
Topics: Humans; Alkaloids; Eye Diseases; Atropine; Pilocarpine; Plants, Medicinal; Caffeine; Plant Extracts; Reserpine
PubMed: 38452806
DOI: 10.1055/a-2283-2350 -
Eye (London, England) May 2024Two quantitative models for myopia have been proposed and used for myopic intervention, one derived from feedback theory, and the other from physiological and mechanical...
BACKGROUND
Two quantitative models for myopia have been proposed and used for myopic intervention, one derived from feedback theory, and the other from physiological and mechanical considerations. This paper shows that they both predict the same results indicating that they are valid and reliable. These models are the only ones that can make predictions about the effect of atropine and lenses on myopia, explain multiple observations heretofore unexplained and offer possible interventions.
OBJECTIVE
Using their predictive power we test the models by calculating and comparing the effect of accommodation, lenses or atropine. The models offer a rationale that makes atropine equivalent to a positive lens for purposes of refractive development.
METHODS
This report includes thought experiments, actual experiments and trials, as well as an analysis of clinical data and integrates and tests results from all of them for far-reaching conclusions.
RESULTS
Both models accurately predict the same myopia progression caused by near work. These models are simple but powerful enough to suggest what treatments are indicated. Interventions for prevention and control of myopia are evaluated analytically, in particular atropine and optical treatments, such as positive lenses and under correction.
CONCLUSION
Optical treatments have enormous potential; atropine is of questionable value since there are ways to get the same or superior effect with lenses of power calculated as described here.
Topics: Atropine; Humans; Accommodation, Ocular; Myopia; Mydriatics; Eyeglasses; Models, Biological; Refraction, Ocular; Disease Progression
PubMed: 38087120
DOI: 10.1038/s41433-023-02884-3 -
Journal of Neuroinflammation Jul 2023Acute exposure to seizurogenic organophosphate (OP) nerve agents (OPNA) such as diisopropylfluorophosphate (DFP) or soman (GD), at high concentrations, induce immediate...
BACKGROUND
Acute exposure to seizurogenic organophosphate (OP) nerve agents (OPNA) such as diisopropylfluorophosphate (DFP) or soman (GD), at high concentrations, induce immediate status epilepticus (SE), reactive gliosis, neurodegeneration, and epileptogenesis as a consequence. Medical countermeasures (MCMs-atropine, oximes, benzodiazepines), if administered in < 20 min of OPNA exposure, can control acute symptoms and mortality. However, MCMs alone are inadequate to prevent OPNA-induced brain injury and behavioral dysfunction in survivors. We have previously shown that OPNA exposure-induced SE increases the production of inducible nitric oxide synthase (iNOS) in glial cells in both short- and long- terms. Treating with a water soluble and highly selective iNOS inhibitor, 1400W, for 3 days significantly reduced OPNA-induced brain changes in those animals that had mild-moderate SE in the rat DFP model. However, such mitigating effects and the mechanisms of 1400W are unknown in a highly volatile nerve agent GD exposure.
METHODS
Mixed-sex cohort of adult Sprague Dawley rats were exposed to GD (132 μg/kg, s.c.) and immediately treated with atropine (2 mg/kg, i.m) and HI-6 (125 mg/kg, i.m.). Severity of seizures were quantified for an hour and treated with midazolam (3 mg/kg, i.m.). An hour post-midazolam, 1400W (20 mg/kg, i.m.) or vehicle was administered daily for 2 weeks. After behavioral testing and EEG acquisition, animals were euthanized at 3.5 months post-GD. Brains were processed for neuroinflammatory and neurodegeneration markers. Serum and CSF were used for nitrooxidative and proinflammatory cytokines assays.
RESULTS
We demonstrate a significant long-term (3.5 months post-soman) disease-modifying effect of 1400W in animals that had severe SE for > 20 min of continuous convulsive seizures. 1400W significantly reduced GD-induced motor and cognitive dysfunction; nitrooxidative stress (nitrite, ROS; increased GSH: GSSG); proinflammatory cytokines in the serum and some in the cerebrospinal fluid (CSF); epileptiform spikes and spontaneously recurring seizures (SRS) in males; reactive gliosis (GFAP + C3 and IBA1 + CD68-positive glia) as a measure of neuroinflammation, and neurodegeneration (especially parvalbumin-positive neurons) in some brain regions.
CONCLUSION
These findings demonstrate the long-term disease-modifying effects of a glial-targeted iNOS inhibitor, 1400W, in a rat GD model by modulating reactive gliosis, neurodegeneration (parvalbumin-positive neurons), and neuronal hyperexcitability.
Topics: Animals; Male; Rats; Atropine; Cytokines; Enzyme Inhibitors; Epilepsy; Gliosis; Midazolam; Neuroglia; Nitric Oxide Synthase Type II; Parvalbumins; Rats, Sprague-Dawley; Seizures; Soman; Status Epilepticus
PubMed: 37438764
DOI: 10.1186/s12974-023-02847-1 -
Circulation Research Sep 2023The phrase complete vagal withdrawal is often used when discussing autonomic control of the heart during exercise. However, more recent studies have challenged this...
BACKGROUND
The phrase complete vagal withdrawal is often used when discussing autonomic control of the heart during exercise. However, more recent studies have challenged this assumption. We hypothesized that cardiac vagal activity increases during exercise and maintains cardiac function via transmitters other than acetylcholine.
METHODS
Chronic direct recordings of cardiac vagal nerve activity, cardiac output, coronary artery blood flow, and heart rate were recorded in conscious adult sheep during whole-body treadmill exercise. Cardiac innervation of the left cardiac vagal branch was confirmed with lipophilic tracer dyes (DiO). Sheep were exercised with pharmacological blockers of acetylcholine (atropine, 250 mg), VIP (vasoactive intestinal peptide; [4Cl-D-Phe6,Leu17]VIP 25 µg), or saline control, randomized on different days. In a subset of sheep, the left cardiac vagal branch was denervated.
RESULTS
Neural innervation from the cardiac vagal branch is seen at major cardiac ganglionic plexi, and within the fat pads associated with the coronary arteries. Directly recorded cardiac vagal nerve activity increased during exercise. Left cardiac vagal branch denervation attenuated the maximum changes in coronary artery blood flow (maximum exercise, control: 63.5±5.9 mL/min, n=8; cardiac vagal denervated: 32.7±5.6 mL/min, n=6, 2.5×10), cardiac output, and heart rate during exercise. Atropine did not affect any cardiac parameters during exercise, but VIP antagonism significantly reduced coronary artery blood flow during exercise to a similar level to vagal denervation.
CONCLUSIONS
Our study demonstrates that cardiac vagal nerve activity actually increases and is crucial for maintaining cardiac function during exercise. Furthermore, our findings show the dynamic modulation of coronary artery blood flow during exercise is mediated by VIP.
Topics: Animals; Sheep; Acetylcholine; Heart; Coronary Vessels; Cardiac Output; Atropine
PubMed: 37641938
DOI: 10.1161/CIRCRESAHA.123.323017 -
European Journal of Ophthalmology Dec 2023Myopia is becoming increasingly common in young generations all over the world, and it is predicted to become the most common cause of blindness and visual impairment in... (Review)
Review
Myopia management algorithm. Annexe to the article titled Update and guidance on management of myopia. European Society of Ophthalmology in cooperation with International Myopia Institute.
Myopia is becoming increasingly common in young generations all over the world, and it is predicted to become the most common cause of blindness and visual impairment in later life in the near future. Because myopia can cause serious complications and vision loss, it is critical to create and prescribe effective myopia treatment solutions that can help prevent or delay the onset and progression of myopia. The scientific understanding of myopia's causes, genetic background, environmental conditions, and various management techniques, including therapies to prevent or postpone its development and slow its progression, is rapidly expanding. However, some significant information gaps exist on this subject, making it difficult to develop an effective intervention plan. As with the creation of this present algorithm, a compromise is to work on best practices and reach consensus among a wide number of specialists. The quick rise in information regarding myopia management may be difficult for the busy eye care provider, but it necessitates a continuing need to evaluate new research and implement it into daily practice. To assist eye care providers in developing these strategies, an algorithm has been proposed that covers all aspects of myopia mitigation and management. The algorithm aims to provide practical assistance in choosing and developing an effective myopia management strategy tailored to the individual child. It incorporates the latest research findings and covers a wide range of modalities, from primary, secondary, and tertiary myopia prevention to interventions that reduce the progression of myopia.
PubMed: 38087768
DOI: 10.1177/11206721231219532