This document provides an overview of butyrylcholinesterase (BChE), including its substrates, inhibitors, structure, mechanism of action, and therapeutic indications. It discusses the biochemistry and genetic variability of BChE, as well as its role in protecting against toxicities and disease. BChE preferentially hydrolyzes butyrylcholine and can also hydrolyze acetylcholine and various drugs like cocaine. Inherited BChE deficiencies have implications for responses to drugs like succinylcholine. Enhancing BChE activity may help treat cocaine abuse and toxicity.
Chemistry of peptide (BPHARM,MPHARM,MSC,BSC)Shikha Popali
THE PRESENTATION DESCRIBING BOND FORMATION OF AMINO ACIDS AND PROTEINS AND COUPLING REAGENTS IN PEPTIDE SYNTHESIS FOLLOWED BY CARBODIMIDES, PHOSPHONIUM AND AMMONIUM SALTS.
HERE PRESENTS AN OLIGONUCLEOTIDE THERAPY, ITS INTRODUCTION TO OLIGONUCLEOTIDE, ITS TECHNIQUES, DEVELOPED METHODS AND THEIR APP,LICATIONS IN PHARMACEUTICAL ARE HERE DISCUSSED IN DETAIL
PEPTIDOMIMETICS , HERE WE HAVE INCLUDED THE INTRODUCTION, CLASSIFICATION, ADVANTAGES , DISADVANTAGES, ITS METHODS PREPARATION, PRINCIPLES OD DRUG DESIGN, ITS CHEMISTRY. STEREOCHEMISTRY, SYNTHESIS AND APPLICATIONS
Chemistry of peptide (BPHARM,MPHARM,MSC,BSC)Shikha Popali
THE PRESENTATION DESCRIBING BOND FORMATION OF AMINO ACIDS AND PROTEINS AND COUPLING REAGENTS IN PEPTIDE SYNTHESIS FOLLOWED BY CARBODIMIDES, PHOSPHONIUM AND AMMONIUM SALTS.
HERE PRESENTS AN OLIGONUCLEOTIDE THERAPY, ITS INTRODUCTION TO OLIGONUCLEOTIDE, ITS TECHNIQUES, DEVELOPED METHODS AND THEIR APP,LICATIONS IN PHARMACEUTICAL ARE HERE DISCUSSED IN DETAIL
PEPTIDOMIMETICS , HERE WE HAVE INCLUDED THE INTRODUCTION, CLASSIFICATION, ADVANTAGES , DISADVANTAGES, ITS METHODS PREPARATION, PRINCIPLES OD DRUG DESIGN, ITS CHEMISTRY. STEREOCHEMISTRY, SYNTHESIS AND APPLICATIONS
SAR versus QSAR, History and development of QSAR, Types of physicochemical
parameters, experimental and theoretical approaches for the determination of
physicochemical parameters such as Partition coefficient, Hammet’s substituent
constant and Taft’s steric constant. Hansch analysis, Free Wilson analysis, 3D-QSAR
approaches like COMFA and COMSIA.
ENZYME INHIBITION THE MOST IMPORTANT TOPIC FOR BIOLOGY AS WELL AS CHEMISTRY PEOPLES. WE HAVE HERE COVERED FOR THE PHARMA STUDENTS THIS WILL MAKE THEM EASY AS WE ARE COLLECTED ALL THE DATA A SINGLE PLACE WICH COVERS ALL THE COTENTS.
CHEMISTRY OF PEPTIDES [M.PHARM, M.SC, BSC, B.PHARM]Shikha Popali
THE CHEMISTRY OF PEPTIDES THE DIFFICULT TO COLLECT DATA FOR READERS , THREFORE HERE WE HAVE COLLECTED ALL THE DATA AT A PLACE AND PROVIDED EASIER TO CHEMISTRIANS.
Presented by Shikha Popali and Harshpal singh Wahi students from Gurunanak college of pharmacy, Nagpur in Department of pharmaceutical Chemistry. The explained topic is seful for every chemistry student and for others too
Quantum Mechanics in Molecular modelingAkshay Kank
This slides gives you the information related to computer aided drug design and its application in drug discovery. Also you learn the Quantum mechanics related to the molecular mechanics. Theory related to molecular modeling and how the molecular modeling helps in drug discovery.
SAR versus QSAR, History and development of QSAR, Types of physicochemical
parameters, experimental and theoretical approaches for the determination of
physicochemical parameters such as Partition coefficient, Hammet’s substituent
constant and Taft’s steric constant. Hansch analysis, Free Wilson analysis, 3D-QSAR
approaches like COMFA and COMSIA.
ENZYME INHIBITION THE MOST IMPORTANT TOPIC FOR BIOLOGY AS WELL AS CHEMISTRY PEOPLES. WE HAVE HERE COVERED FOR THE PHARMA STUDENTS THIS WILL MAKE THEM EASY AS WE ARE COLLECTED ALL THE DATA A SINGLE PLACE WICH COVERS ALL THE COTENTS.
CHEMISTRY OF PEPTIDES [M.PHARM, M.SC, BSC, B.PHARM]Shikha Popali
THE CHEMISTRY OF PEPTIDES THE DIFFICULT TO COLLECT DATA FOR READERS , THREFORE HERE WE HAVE COLLECTED ALL THE DATA AT A PLACE AND PROVIDED EASIER TO CHEMISTRIANS.
Presented by Shikha Popali and Harshpal singh Wahi students from Gurunanak college of pharmacy, Nagpur in Department of pharmaceutical Chemistry. The explained topic is seful for every chemistry student and for others too
Quantum Mechanics in Molecular modelingAkshay Kank
This slides gives you the information related to computer aided drug design and its application in drug discovery. Also you learn the Quantum mechanics related to the molecular mechanics. Theory related to molecular modeling and how the molecular modeling helps in drug discovery.
Assessment of haemodynamics a critically ill patient and its management has always been a matter if debate. Over time a lot of studies and therapeutic interventions have been carried out. This presentation is a review of such interventions and their impact on the outcome.
Lecture 11 from a college level neuropharmacology course taught in the spring 2012 semester by Brian J. Piper, Ph.D. (psy391@gmail.com) at Willamette University.
cholingeric and Anticholinesterase drug in detail .this ppt contains introduction ,mechanism of action ,pharmacological action ,uses and adverse effect of the drug
Ethanol (CH3CH2OH), or beverage alcohol, is a two-carbon alcohol
that is rapidly distributed in the body and brain. Ethanol alters many
neurochemical systems and has rewarding and addictive properties. It
is the oldest recreational drug and likely contributes to more morbidity,
mortality, and public health costs than all illicit drugs combined. The
5th edition of the Diagnostic and Statistical Manual of Mental Disorders
(DSM-5) integrates alcohol abuse and alcohol dependence into a single
disorder called alcohol use disorder (AUD), with mild, moderate,
and severe subclassifications (American Psychiatric Association, 2013).
In the DSM-5, all types of substance abuse and dependence have been
combined into a single substance use disorder (SUD) on a continuum
from mild to severe. A diagnosis of AUD requires that at least two of
the 11 DSM-5 behaviors be present within a 12-month period (mild
AUD: 2–3 criteria; moderate AUD: 4–5 criteria; severe AUD: 6–11 criteria).
The four main behavioral effects of AUD are impaired control over
drinking, negative social consequences, risky use, and altered physiological
effects (tolerance, withdrawal). This chapter presents an overview
of the prevalence and harmful consequences of AUD in the U.S.,
the systemic nature of the disease, neurocircuitry and stages of AUD,
comorbidities, fetal alcohol spectrum disorders, genetic risk factors, and
pharmacotherapies for AUD.
Lung Cancer: Artificial Intelligence, Synergetics, Complex System Analysis, S...Oleg Kshivets
RESULTS: Overall life span (LS) was 2252.1±1742.5 days and cumulative 5-year survival (5YS) reached 73.2%, 10 years – 64.8%, 20 years – 42.5%. 513 LCP lived more than 5 years (LS=3124.6±1525.6 days), 148 LCP – more than 10 years (LS=5054.4±1504.1 days).199 LCP died because of LC (LS=562.7±374.5 days). 5YS of LCP after bi/lobectomies was significantly superior in comparison with LCP after pneumonectomies (78.1% vs.63.7%, P=0.00001 by log-rank test). AT significantly improved 5YS (66.3% vs. 34.8%) (P=0.00000 by log-rank test) only for LCP with N1-2. Cox modeling displayed that 5YS of LCP significantly depended on: phase transition (PT) early-invasive LC in terms of synergetics, PT N0—N12, cell ratio factors (ratio between cancer cells- CC and blood cells subpopulations), G1-3, histology, glucose, AT, blood cell circuit, prothrombin index, heparin tolerance, recalcification time (P=0.000-0.038). Neural networks, genetic algorithm selection and bootstrap simulation revealed relationships between 5YS and PT early-invasive LC (rank=1), PT N0—N12 (rank=2), thrombocytes/CC (3), erythrocytes/CC (4), eosinophils/CC (5), healthy cells/CC (6), lymphocytes/CC (7), segmented neutrophils/CC (8), stick neutrophils/CC (9), monocytes/CC (10); leucocytes/CC (11). Correct prediction of 5YS was 100% by neural networks computing (area under ROC curve=1.0; error=0.0).
CONCLUSIONS: 5YS of LCP after radical procedures significantly depended on: 1) PT early-invasive cancer; 2) PT N0--N12; 3) cell ratio factors; 4) blood cell circuit; 5) biochemical factors; 6) hemostasis system; 7) AT; 8) LC characteristics; 9) LC cell dynamics; 10) surgery type: lobectomy/pneumonectomy; 11) anthropometric data. Optimal diagnosis and treatment strategies for LC are: 1) screening and early detection of LC; 2) availability of experienced thoracic surgeons because of complexity of radical procedures; 3) aggressive en block surgery and adequate lymph node dissection for completeness; 4) precise prediction; 5) adjuvant chemoimmunoradiotherapy for LCP with unfavorable prognosis.
These lecture slides, by Dr Sidra Arshad, offer a quick overview of physiological basis of a normal electrocardiogram.
Learning objectives:
1. Define an electrocardiogram (ECG) and electrocardiography
2. Describe how dipoles generated by the heart produce the waveforms of the ECG
3. Describe the components of a normal electrocardiogram of a typical bipolar leads (limb II)
4. Differentiate between intervals and segments
5. Enlist some common indications for obtaining an ECG
Study Resources:
1. Chapter 11, Guyton and Hall Textbook of Medical Physiology, 14th edition
2. Chapter 9, Human Physiology - From Cells to Systems, Lauralee Sherwood, 9th edition
3. Chapter 29, Ganong’s Review of Medical Physiology, 26th edition
4. Electrocardiogram, StatPearls - https://www.ncbi.nlm.nih.gov/books/NBK549803/
5. ECG in Medical Practice by ABM Abdullah, 4th edition
6. ECG Basics, http://www.nataliescasebook.com/tag/e-c-g-basics
The prostate is an exocrine gland of the male mammalian reproductive system
It is a walnut-sized gland that forms part of the male reproductive system and is located in front of the rectum and just below the urinary bladder
Function is to store and secrete a clear, slightly alkaline fluid that constitutes 10-30% of the volume of the seminal fluid that along with the spermatozoa, constitutes semen
A healthy human prostate measures (4cm-vertical, by 3cm-horizontal, 2cm ant-post ).
It surrounds the urethra just below the urinary bladder. It has anterior, median, posterior and two lateral lobes
It’s work is regulated by androgens which are responsible for male sex characteristics
Generalised disease of the prostate due to hormonal derangement which leads to non malignant enlargement of the gland (increase in the number of epithelial cells and stromal tissue)to cause compression of the urethra leading to symptoms (LUTS
ARTIFICIAL INTELLIGENCE IN HEALTHCARE.pdfAnujkumaranit
Artificial intelligence (AI) refers to the simulation of human intelligence processes by machines, especially computer systems. It encompasses tasks such as learning, reasoning, problem-solving, perception, and language understanding. AI technologies are revolutionizing various fields, from healthcare to finance, by enabling machines to perform tasks that typically require human intelligence.
Title: Sense of Taste
Presenter: Dr. Faiza, Assistant Professor of Physiology
Qualifications:
MBBS (Best Graduate, AIMC Lahore)
FCPS Physiology
ICMT, CHPE, DHPE (STMU)
MPH (GC University, Faisalabad)
MBA (Virtual University of Pakistan)
Learning Objectives:
Describe the structure and function of taste buds.
Describe the relationship between the taste threshold and taste index of common substances.
Explain the chemical basis and signal transduction of taste perception for each type of primary taste sensation.
Recognize different abnormalities of taste perception and their causes.
Key Topics:
Significance of Taste Sensation:
Differentiation between pleasant and harmful food
Influence on behavior
Selection of food based on metabolic needs
Receptors of Taste:
Taste buds on the tongue
Influence of sense of smell, texture of food, and pain stimulation (e.g., by pepper)
Primary and Secondary Taste Sensations:
Primary taste sensations: Sweet, Sour, Salty, Bitter, Umami
Chemical basis and signal transduction mechanisms for each taste
Taste Threshold and Index:
Taste threshold values for Sweet (sucrose), Salty (NaCl), Sour (HCl), and Bitter (Quinine)
Taste index relationship: Inversely proportional to taste threshold
Taste Blindness:
Inability to taste certain substances, particularly thiourea compounds
Example: Phenylthiocarbamide
Structure and Function of Taste Buds:
Composition: Epithelial cells, Sustentacular/Supporting cells, Taste cells, Basal cells
Features: Taste pores, Taste hairs/microvilli, and Taste nerve fibers
Location of Taste Buds:
Found in papillae of the tongue (Fungiform, Circumvallate, Foliate)
Also present on the palate, tonsillar pillars, epiglottis, and proximal esophagus
Mechanism of Taste Stimulation:
Interaction of taste substances with receptors on microvilli
Signal transduction pathways for Umami, Sweet, Bitter, Sour, and Salty tastes
Taste Sensitivity and Adaptation:
Decrease in sensitivity with age
Rapid adaptation of taste sensation
Role of Saliva in Taste:
Dissolution of tastants to reach receptors
Washing away the stimulus
Taste Preferences and Aversions:
Mechanisms behind taste preference and aversion
Influence of receptors and neural pathways
Impact of Sensory Nerve Damage:
Degeneration of taste buds if the sensory nerve fiber is cut
Abnormalities of Taste Detection:
Conditions: Ageusia, Hypogeusia, Dysgeusia (parageusia)
Causes: Nerve damage, neurological disorders, infections, poor oral hygiene, adverse drug effects, deficiencies, aging, tobacco use, altered neurotransmitter levels
Neurotransmitters and Taste Threshold:
Effects of serotonin (5-HT) and norepinephrine (NE) on taste sensitivity
Supertasters:
25% of the population with heightened sensitivity to taste, especially bitterness
Increased number of fungiform papillae
Report Back from SGO 2024: What’s the Latest in Cervical Cancer?bkling
Are you curious about what’s new in cervical cancer research or unsure what the findings mean? Join Dr. Emily Ko, a gynecologic oncologist at Penn Medicine, to learn about the latest updates from the Society of Gynecologic Oncology (SGO) 2024 Annual Meeting on Women’s Cancer. Dr. Ko will discuss what the research presented at the conference means for you and answer your questions about the new developments.
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Couples presenting to the infertility clinic- Do they really have infertility...Sujoy Dasgupta
Dr Sujoy Dasgupta presented the study on "Couples presenting to the infertility clinic- Do they really have infertility? – The unexplored stories of non-consummation" in the 13th Congress of the Asia Pacific Initiative on Reproduction (ASPIRE 2024) at Manila on 24 May, 2024.
Prix Galien International 2024 Forum ProgramLevi Shapiro
June 20, 2024, Prix Galien International and Jerusalem Ethics Forum in ROME. Detailed agenda including panels:
- ADVANCES IN CARDIOLOGY: A NEW PARADIGM IS COMING
- WOMEN’S HEALTH: FERTILITY PRESERVATION
- WHAT’S NEW IN THE TREATMENT OF INFECTIOUS,
ONCOLOGICAL AND INFLAMMATORY SKIN DISEASES?
- ARTIFICIAL INTELLIGENCE AND ETHICS
- GENE THERAPY
- BEYOND BORDERS: GLOBAL INITIATIVES FOR DEMOCRATIZING LIFE SCIENCE TECHNOLOGIES AND PROMOTING ACCESS TO HEALTHCARE
- ETHICAL CHALLENGES IN LIFE SCIENCES
- Prix Galien International Awards Ceremony
New Directions in Targeted Therapeutic Approaches for Older Adults With Mantl...i3 Health
i3 Health is pleased to make the speaker slides from this activity available for use as a non-accredited self-study or teaching resource.
This slide deck presented by Dr. Kami Maddocks, Professor-Clinical in the Division of Hematology and
Associate Division Director for Ambulatory Operations
The Ohio State University Comprehensive Cancer Center, will provide insight into new directions in targeted therapeutic approaches for older adults with mantle cell lymphoma.
STATEMENT OF NEED
Mantle cell lymphoma (MCL) is a rare, aggressive B-cell non-Hodgkin lymphoma (NHL) accounting for 5% to 7% of all lymphomas. Its prognosis ranges from indolent disease that does not require treatment for years to very aggressive disease, which is associated with poor survival (Silkenstedt et al, 2021). Typically, MCL is diagnosed at advanced stage and in older patients who cannot tolerate intensive therapy (NCCN, 2022). Although recent advances have slightly increased remission rates, recurrence and relapse remain very common, leading to a median overall survival between 3 and 6 years (LLS, 2021). Though there are several effective options, progress is still needed towards establishing an accepted frontline approach for MCL (Castellino et al, 2022). Treatment selection and management of MCL are complicated by the heterogeneity of prognosis, advanced age and comorbidities of patients, and lack of an established standard approach for treatment, making it vital that clinicians be familiar with the latest research and advances in this area. In this activity chaired by Michael Wang, MD, Professor in the Department of Lymphoma & Myeloma at MD Anderson Cancer Center, expert faculty will discuss prognostic factors informing treatment, the promising results of recent trials in new therapeutic approaches, and the implications of treatment resistance in therapeutic selection for MCL.
Target Audience
Hematology/oncology fellows, attending faculty, and other health care professionals involved in the treatment of patients with mantle cell lymphoma (MCL).
Learning Objectives
1.) Identify clinical and biological prognostic factors that can guide treatment decision making for older adults with MCL
2.) Evaluate emerging data on targeted therapeutic approaches for treatment-naive and relapsed/refractory MCL and their applicability to older adults
3.) Assess mechanisms of resistance to targeted therapies for MCL and their implications for treatment selection
Recomendações da OMS sobre cuidados maternos e neonatais para uma experiência pós-natal positiva.
Em consonância com os ODS – Objetivos do Desenvolvimento Sustentável e a Estratégia Global para a Saúde das Mulheres, Crianças e Adolescentes, e aplicando uma abordagem baseada nos direitos humanos, os esforços de cuidados pós-natais devem expandir-se para além da cobertura e da simples sobrevivência, de modo a incluir cuidados de qualidade.
Estas diretrizes visam melhorar a qualidade dos cuidados pós-natais essenciais e de rotina prestados às mulheres e aos recém-nascidos, com o objetivo final de melhorar a saúde e o bem-estar materno e neonatal.
Uma “experiência pós-natal positiva” é um resultado importante para todas as mulheres que dão à luz e para os seus recém-nascidos, estabelecendo as bases para a melhoria da saúde e do bem-estar a curto e longo prazo. Uma experiência pós-natal positiva é definida como aquela em que as mulheres, pessoas que gestam, os recém-nascidos, os casais, os pais, os cuidadores e as famílias recebem informação consistente, garantia e apoio de profissionais de saúde motivados; e onde um sistema de saúde flexível e com recursos reconheça as necessidades das mulheres e dos bebês e respeite o seu contexto cultural.
Estas diretrizes consolidadas apresentam algumas recomendações novas e já bem fundamentadas sobre cuidados pós-natais de rotina para mulheres e neonatos que recebem cuidados no pós-parto em unidades de saúde ou na comunidade, independentemente dos recursos disponíveis.
É fornecido um conjunto abrangente de recomendações para cuidados durante o período puerperal, com ênfase nos cuidados essenciais que todas as mulheres e recém-nascidos devem receber, e com a devida atenção à qualidade dos cuidados; isto é, a entrega e a experiência do cuidado recebido. Estas diretrizes atualizam e ampliam as recomendações da OMS de 2014 sobre cuidados pós-natais da mãe e do recém-nascido e complementam as atuais diretrizes da OMS sobre a gestão de complicações pós-natais.
O estabelecimento da amamentação e o manejo das principais intercorrências é contemplada.
Recomendamos muito.
Vamos discutir essas recomendações no nosso curso de pós-graduação em Aleitamento no Instituto Ciclos.
Esta publicação só está disponível em inglês até o momento.
Prof. Marcus Renato de Carvalho
www.agostodourado.com
Pulmonary Thromboembolism - etilogy, types, medical- Surgical and nursing man...VarunMahajani
Disruption of blood supply to lung alveoli due to blockage of one or more pulmonary blood vessels is called as Pulmonary thromboembolism. In this presentation we will discuss its causes, types and its management in depth.
Ozempic: Preoperative Management of Patients on GLP-1 Receptor Agonists Saeid Safari
Preoperative Management of Patients on GLP-1 Receptor Agonists like Ozempic and Semiglutide
ASA GUIDELINE
NYSORA Guideline
2 Case Reports of Gastric Ultrasound
4. BChE Introduction
• Preferentially hydrolyzes butyrylcholine, but also hydrolyzes acetylcholine
– Function thought to be a scavenger of toxic molecules
• Serum BChE is synthesized in the liver and then secreted
– But also synthesized in the lungs, heart, and brain
• > 11 different isoforms
– > 60 isoforms of human P450
• Many different names
– Pseudo, plasma, serum, benzoyl, false, non-specific, or type II cholinesterase
– Acyl hydrolase or Acylcholine acylhydrolase
• Member of the type-b carboxylesterase/lipase family
– Inhibited by organophosphates
• type a’s hydrolyze OPs, type c’s do not interact)
4
5. History
• 1920’s
– Loewi in Austria
• Awarded Nobel Prize for work on cholinesterase, etc.
• 1940’s
– Mendel in Toronto, Canada
• “True cholinesterase”: present in red blood cells
• “pseudo-cholinesterase”: present in plasma
5
6. More History
• 1950’s:
– Patients with schizophrenia treated with electroshock
– Good therapeutic success, but also overstimulated some
patients’ skeletal muscles broken bones
– Succinylcholine would be injected to avoid contractions
• Most times, paralyzing effect is over in a few minutes
– BChE rapidly hydrolyzes succinylcholine
• In some patients, the effect can last > 1 hour
• 1957:
– BChE activity of plasma from patients and their parents was
analyzed
– Genetic difference in BChE activity in humans was described
6
7. • 2 classes
Animal Cholinesterases
– Based on their substrate specificity and susceptibility to inhibitors
• Acetylcholinesterase (AChE)
– Hydrolyzes ACh faster than other choline esters
– Much less active on BCh
– Inhibited by excess substrate
• Butyrylcholinesterase (BChE)
– Preferentially hydrolyzes BCh
– Also hydrolyzes Ach (4X slower)
– Activated by excess substrate
– Hydrolyzes a large number of ester-containing compounds
• Species with higher BChE activity in plasma
– Human, monkeys, guinea pig, mice
• Species with higher AChE activity in plasma
– Rat, bovine, sheep
7
8. Cholinesterases
• Acetylcholinesterase
– Function is to hydrolyze acetylcholine released at the synaptic cleft and
neuromuscular junction in response to nerve action potential
– Loss of AChE activity muscle paralysis, seizures, death
– Extremely efficient – rate approaches diffusion
– Membrane bound
• Butyrylcholinesterase
– Physiological role is unclear – no endogenous substrate
• Lipoprotein metabolism
• Myelin maintenance
• Cellular adhesion and neurogenesis
• Processing of amyloid precursor protein (implications for Alzheimer’s)
– Individuals with no BChE have no physiological abnormalities
– Plays an important role in pharmacology and toxicology
8
9. Localization Differences
AChE BChE
Brain Plasma (relatively abundant, ~ 2-3 mg/L)
Muscle Liver
Erythrocyte membrane Smooth muscle
Nerve endings Intestinal mucosa
Spleen Pancreas
Lung Heart
Kidney
Lung
White matter of the brain
No carboxylesterases in human blood
Are present in high amounts in mice, rat, rabbit, horse, cat, and tiger blood
9
10. Selective Inhibitors
AChE BChE
H
H N O
N O N
N O
N
O
N
Phenserine
Phenethyl-norcymserine
Huperzine A
Ethopromazine
BW284C51
10
11. •
Inherited BChE Deficiency
Not clinically significant until plasma activity is reduced to 75% of normal
• No physical characteristics correlate with deficiency
• Most often recognized when respiratory paralysis unexpectedly persists for a
prolonged period after a dose of succinylcholine
• One of the oldest (50’s) and best-studied examples of a pharmacogenetic
condition
– Normally,
• 90-95% of an IV dose of succinylcholine is hydrolyzed before it reaches the neuromuscular
junction
• 5-10% of the dose flaccid paralysis in 1 min
• Skeletal muscle returns to normal after 5 min
– If BChE deficient,
• Duration of paralytic effect can last 8 hours
• Most common in Europeans and rare in Asians
11
12. Genetic Variants
• 96% of population is homozygous for normal genotype
• 4% of the population:
– Atypical (Dibucaine) resistant (most of the 4%) and F- resistant
• Measure % inhibition of enzyme activity in presence of dibucaine or F-
• WT is inhibited 80% and 60%, respectively
• Homozygous variants are inhibited only 20% and 36%, respectively
• Succinylcholine paralysis for > 1hr
– ~ 20 different “silent” genotypes identified 0-2% WT activity
• 1 in 100,000
• No functional BChE synthesized
• Succinylcholine paralysis for > 8 hours
– Cynthiana variant increased amount of BCh (3X)
• Resistant to succinylcholine treatment
– Johannesburg variant same amount of BChE, but increased activity
12
13. •
Genetic Variability
Deficiencies are due to one or more inherited abnormal alleles
– Failure to produce normal amounts of the enzyme
– Production of BChE with altered structure and activity
• > 11 different variants – all have reduced activity compared to WT
mutation homozygous
– U “usual” WT
– A “atypical” Asp70Gly 1:3,000
“dibucaine resistant”
– K Kalow form Ala539Thr
– J Glu497Val 1:150,000
– F1 F- resistant Thr247Met
– F2 F- resistant Gly390Val
– H Val142Met
– S silent 129STOP 1:100,000
13
14. Biochemical Features
• MW ~ 68,000 Da (602 AA’s)
– Human AChE is ~ 60,000 Da, human CE-1 is ~ 63,000 Da and P450s are ~ 50,000 Da
• 9 different glycosylation sites
• 3 internal disulfide bonds
– Cys65-Cys92, Cys252-Cys263, Cys400-Cys519
• Homotetramer
• Made up of 2 dimers linked by a disulfide bond (Cys571-Cys571)
• Catalytic Triad
– Ser198, Glu325, His438 (akin to hCEs)
• “Atypical” variant is identical in every way, except for one AA
– Reduced binding affinity (2X) reduced activity
14
15. Interspecies Similarities
• Protein Sequence Identity (and Homology) with
Human BChE (~ 50 mg costs $350)
– Rabbit 91% (93%)
– Horse 90% (94%)
– Cat 87% (91%)
– Dog 86% (91%)
– Mouse 80% (87%)
– Rat 79% (87%)
– Chicken 71% (83%)
– Human AChE 53% (65%)
15
16. Crystal Structure of BChE
• Comparison to AChE
– Catalytic triads of both are at the bottom of a 20 Å-deep
gorge
• Gorge of BChE is lined with hydrophobic residues instead of
aromatic ones
– Acyl binding pockets are different
• 2 Phe’s Val, Leu bulkier substrates can be accommodated
– Peripheral site
• At the outer rim of the gorges
• Proposed to be the initial binding site – attraction center for
substrates
– Anionic site
• Found half-way down the gorges
• In between the peripheral and acylation sites
16
18. BChE Mechanism
ES1: substrate binds to PAS (Asp70)
ES2: substrate slides down the active
site gorge (Trp 82)
ES3: substrate rotates to horizontal
position for hydrolysis
(Ser-198)
18
19. Choline Substrates
O
+ O N
+ O
N O + N
O O
acetylcholine
succinylcholine
(powerful muscle relaxant)
O + S
N N
O O
butyrylcholine butyrylthiocholine
(optimal substrate)
19
20. Prodrugs
N
H
CPT-11
O O
O
O O N O O N
O O
Heroin
H
(Silent variants N
Cannot hydrolyze) HO
Bambuterol
20
21. Drugs
O
O
N
O HO
O
H3C N
N
H
Tetracaine
Benzactyzine
O OH
O
O
Aspirin
21
22. Inhibitors
H3C N O
O
O
P
N S
O
Amitryptiline
Phosphonothiolate
Cocaine Analog
22
23. Kinetic Parameters
Ki (µM) kcat (min-1) plasma t1/2
Butyrylthiocholine ~ 20 33,900
Benzoylcholine ~ 8000
Succinylcholine ~ 1500
Aspirin 5,000-12,000
(+) Cocaine (synthetic) ~5 7500 seconds
(-) Cocaine (natural) ~ 10 3.9 45-90 min
Butyryl and propionyl choline are hydrolyzed ~ 2X faster than acetyl choline
KM’s for (+) and (-) cocaine are 10 and 14 µM, respectively
23
26. Cocaine Structure
BCh (-) cocaine • Carbonyl C-N distance
– BCh
• 4.92 Å
– Cocaine
• 5.23 Å (benzoyl)
• 2.95 Å (methyl)
– Explains hydrolysis at
benzoyl
By BChE
• Non-enzymatic
hydrolysis
methyl > benzoyl
26
27. BChE Mechanism
ES1: substrate binds to PAS (Asp70)
ES2: substrate slides down the active
site gorge (Trp 82)
ES3: substrate rotates to horizontal
position for hydrolysis
(Ser-198)
MD simulations: cocaine goes
through same pathway
Difference in (+) vs. (-) cocaine
is in the rotation step
27
28. Cocaine Hydrolysis
H C N 3 O
O
OH
H3C N O
BChE
Ecgonine Methyl Ester (EME)
O hCE-2 ~45%
O
O hCE-1 H3C N O
(-) Cocaine OH
O
O
cocaine hydrolysis 95% of metabolites Benzoyl ecgonine (BE)
~45%
28
29. Cocaine Metabolism
• EME
– vasodilative effects
• BE
– potent vasoconstriction effects
• Norcocaine
– local anesthetic and hepato- and cardiotoxic properties
• Plasma BChE accounts for all the cocaine hydrolysis in
blood
• Deficiency in BChE shifts metabolism to norcocaine and BE
• Enhancing BChE may mediate cocaine-induced
complications
29
30. Cocaine Toxicity Rats
• Tetraisopropylpyrophosphoramide (iso-OMPA)
– Selective BChE inhibitor
– Increases cocaine lethality in mice and rats
• Exogenous BChE in rats
– 400-800X (5000 IU IV-7.8 mg/kg IV) increase in plasma
levels
• decrease in cocaine-induced: locomotor activity, hypertension,
and cardiac arrhythmias
• saline-induced rats exhibited no change
– 3200-6400X increase protection against seizures and
death
30
31. Cocaine Toxicity Monkeys
• Monkeys have different basal BChE activities than
rats
– Squirrel monkeys used
– + saline, + plasma, + plasma + BChE
– Cocaine 3 mg/kg IV
– BChE half-life = 72 h (rhesus monkeys)
– 3X decrease in [cocaine], 3X increase in peak [EME], no
change in [BE]
31
32. Cocaine Abuse and Toxicity in Humans
• Cocaine abuse is major medical and public health problem
– Affected > 40 million in US since 1980
• ~ 400,000 daily users in US
• ~ 5,000 new users each day
– Overdose respiratory depression, cardiac arrhythmia, acute hypertension
• Serum [cocaine] on overdose ~ 20 mg/L
– Requires > 100 mg BChE for “timely” detoxification
• Increase BChE levels to treat cocaine abuse and toxicity
– ~ 12X increase in BChE (3-37 µg/mL) decreases t1/2 of cocaine (2 µg/mL) in plasma
from 116 to 10 min (~ 12X)
– Higher turnover than catalytic antibodies for cocaine
• Patients with lower BChE activity more severe problems
– Acceleration of benzoylester hydrolysis
32
33. BChE Variants for Cocaine Toxicity
• Used molecular dynamic simulations to
– Optimize hydrogen bonding energies between oxyanion
hole and carbonyl oxygen on benzoyl group of (-) cocaine
– Simulated the transition state
• A199S/F227A/A328W/Y332G BChE Mutant
– Engineered BChE mutant that hydrolyzes cocaine very
efficiently
• WT (kcat/KM): ~ 1 X 106 M min-1
• Mutant: (kcat/KM): ~ 1.4 X 108 M min-1
• ~ 140X increase
• Half-life in plasma decreases from 45-90 min to 18-36 s
33
34. Organophosphorous Compounds (OPs)
O CH3 O H3C CH3
O
P P CH3
F O CH3 H3C O N P N CH3
H 3C H3C S
CH3 O
H3C
Sarin N
VX
CH3
Tabun
AChE inhibitor – developed as a pesticide (1952)
most deadly nerve agent in existence
3X more deadly than sarin
300 g is fatal
Widely used as: pesticides, plasticizers, pharmaceuticals, chemical warfare agents
"It's one of those things we wish we could disinvent."
- Stanley Goodspeed, on VX nerve agent
34
35. OP Poisoning Mechanism – “Aging”
Ser
Ser
OH O
O
O
P
H3C O
P
H3C O O
O NO2
O
paraoxon
H3C
H3C HO NO2
H2O
- BChE is inactivated by these organophosphates phosphonylated enzyme
- point mutations in the active site of BChE (inactivated)
efficient organophosphate hydrolase
35
36. OP Poisoning
• Extrapolate rhesus monkey data to humans
– ~ 150 mg human BChE in a 70 kg human can protect against
• 2X LD50 of soman
• 1.5X LD50 of VX
• Want to reduce initial blood levels of OPs by 50% in <10 s
• Protection of at least 30% of red blood cell AChE activity
• Intrinsically limited since its binding is stoichiometric to OPs
– Requires a significant amount of enzyme to detoxify a lethal dose
– To make a more a more efficient OP hydrolyzing enzyme:
• Use crystal structures of human BChE to direct mutations
• Use random mutagenesis of human BCHE to create a library of variants
• Bioscavenger (DVC) and Protexia (Pharmathene) in development for
Army
– Human plasma derived and recombinant (probably mutated) versions of
human BChE
– For pre- and post-exposure to chemical warfare agents 36
37. Exogenous BChE Therapy
• BChE chosen instead of AChE because it:
– Comprises 0.1 % of human plasma protein
• AChE is found only in the erythrocyte membrane
– Can be purified in large amounts from human serum
• AChE from other species could be immunoreactive
– Has a larger active site (200 Å3 larger)
• more substrates will be accommodated
– Has a long half-life in vivo (8-12 days)
• Single injection could increase plasma levels of BChE for several days
• No adverse FX reported with increased BChE plasma activity
– Is thermally stable on prolonged storage
37
38. Alzheimer’s Disease
• Chronic and progressive neurodegenerative disease
– Degeneration of cholinergic neurons loss of neurotransmission
– Reduced levels of Ach
• Leading cause of dementia among older people – affects:
– 10% of people > 65 years old
– 50% of people > 85 years old
• Aging population numbers could increase exponentially
• Reversible AChE inhibitors are viable therapies for AD
– Protect residual ACh levels in the brains of patients with AD
• Tacrine (1993) Donepezil (1996)
• Rivastigmine (2000) Galantamine (2001)
– However, associated with ADRs: liver damage, nausea, vomiting
38
39. AChE
Inhibitors
for AD • Benefits of
treatment
are not
sustained
long-term
and illness
continues
to progress
Confidential 39
40. Alzheimer’s Disease
• AChE levels decrease 85-90% at the more severe
stages of AD
• BChE levels increase 2X
– Normal brain: 10-15% of cholinergic neurons possess BChE not AChE
– Brain affected by AD: glial cells express and secrete more BChE
– Also BChE can catalyze:
• Amyloid precursor protein β-amyloid proteins plaques AD
– Maybe increased BChE activity increased risk of AD
• BChE inhibition may provide therapeutic value at
later stages
• Novel BChE inhibitors were recently described
(2005):
– Tacrine heterobivalent ligands
– Flexible docking procedures
– Molecular modeling studies
40
41. Novel BChE Inhibitors for AD
Tacrine analogs
427X preference for binding BChE (Ki = 110 pM) over AChE
Confirmed extra interaction sites in the mid-gorge and peripheral sites of BChE
41
42. •
Summary than AChE
BChE can metabolize a broader spectrum esterase
• There is an important pharmacogenetic condition that is associated with
BChE activity
• The binding and catalysis of cocaine hydrolysis has been described using a
host of different techniques
• Organophosphorus compounds can act MBIs of BChE
• Administration of exogenous BChE could be a useful therapy for certain
toxic and overdose situations
• Inhibitors of BChE are being developed to treat AD
42