Module 4 Biomedical Science Showcase PDF

MODULE 4: BIOMEDICAL SCIENCE SHOWCASE MODULE 4.1: FEVER AND THERMOREGULATION ❖ Define homeostasis and explain how whole body homeostasis maintains optimal environment for cell function. ❖ Explain why regulating core temperature is important for all multicellular animals What is...

MODULE 4: BIOMEDICAL SCIENCE SHOWCASE MODULE 4.1: FEVER AND THERMOREGULATION ❖ Define homeostasis and explain how whole body homeostasis maintains optimal environment for cell function. ❖ Explain why regulating core temperature is important for all multicellular animals What is Maintenance of a relatively stable internal environment homeostasis? of an organism What is it geared Geared towards (create environment) optimal protein towards? function throughout the body → Notwithstanding changes in the external (ambient) environment Why regulating core temperature is important for all multicellular animals? Biological molecules (proteins, enzymes) function best at specific temperatures (optimal temperatures that they can hold their shape) Shifts from the optimal temperatures → change the protein shape → lose their function Membranes may rupture at high temperature → denaturation What is denaturation (sự Unfolding biến tính)? the protein from Causes? Factors its 3D shape by that cause? the disruption of hydrogen bonds between amino acids → loss of biological activity  Factors that disrupt hydrogen bonds: + Temperature + pH + Ions in the solution (salts) + Solvents (polar molecules) → dissolve proteins → Homeostasis will regulate these factors How does Reflexive (or self regulating): unconscious homeostasis work? Regulatory systems + Endocrine (nội tiết) + Nervous system-Autonomic (ANS) What is the Feedback process of reflex loops: process of control? # types of feedback/reflex reflexes control Negative feedback loops + Self regulatory (nature) + Lead to stabilization between stimulus and response + Oscillate at the equilibrium balance (towards the mean) Positive feedback loops: Amplification What is the process of a negative feedback loop? Thermoregulation is a negative feedback loop Stimulus (kích thích) (what is regulated) → Receptor (cơ quan thụ cảm) detects a change in the stimulus →  carries information towards integration center (brain or spinal cord) - afferent pathway (xung thần kinh hướng tâm) → Control center checks if the information coming from the sensor matches the intended output → Communicates with the response system to respond - efferent pathway (xung thần kinh ly tâm) → Effector produces the response → Back to homeostasis Examples of Stable blood glucose levels in body negative feedback in physiology Regulation of blood pressure *MAP: mean arterial blood pressure (huyết áp động mạch) ❖ Distinguish between somatic and visceral sensation ❖ Distinguish between somatic and visceral motor response # between somatic Somatic sensation: and visceral + Sensory information from “body wall” (skin, skeletal sensation? muscles, bones and joints) + Sensory information that the are (or can be) consciously aware of from external environment Visceral sensation: + Sensory information from internal organs of the body  (heart, blood vessels, lungs, GI tract and bladder) + Sensory information that we are not consciously aware of # between somatic Somatic response: and visceral + Skeletal muscle activity (cơ vân) response? + Movement of joints and limbs (and respiration) + Voluntary movement Visceral response: + Smooth (cơ trơn) and cardiac muscle (cơ tim) related activity (and glandular secretion) + Involuntary + Typically associated with homeostasis How are sensory Information about and motor external and internal responses environment is connected? detected by sensors → passed through the afferent pathway to the CNS (integration center) → passed back to the muscle via the efferent pathway → The motor systems will then activate the effectors What is the Specific division of the nervous system that controls autonomous visceral motor system nervous system (ANS)? Divided into: + Sympathetic nervous system: Regulates reflexes (fear flight or fight reflexes) Responses that increase heart rate / respiratory rate… → Prepare our body to either run away from a threat or to engage and fight with that threat + Parasympathetic nervous system Rest and digest Processes involved when we are not under threat ⇒ Thermoregulatory reflexes involve changes in activity of the sympathetic nervous system. ❖ Explain how chemicals and receptors interact with each other and describe how information is communicated between cells ❖ Define an endocrine hormone, and explain how hormones act ❖ Explain the difference between endocrine hormonal and neural signalling How does the Cells communicate with endocrine system each other via chemical signals. facilitate chemical The cell (endocrine or signaling? neuro-secretory) released hormones (chemical signals)  into the endocrine glands → the glands transport these signals to the target cell via the circulatory system (bloodstream) How does the Neurons communicate with nervous system their target cell via facilitate chemical neurotransmitters (chemical signaling? signals), but signaling is restricted to only the target cell The neurotransmitters are released into the gap (synaptic cleft) between the neuron and its target cell → effects are restricted to the adjacent cell How does a cell Chemical signaling know that the molecules (ligands) are signal is intended detected by a receptor on the for it? cell. + Neurotransmitters + Hormones + Inflammatory mediators In order to activate the target cell, ligands bind to receptors on the target cell → initiates events inside the cell that produce a response. The presence and expression of the receptor on the cell will determine whether the cell will respond to the ligand. How does receptor-ligand binding work? There are many different chemicals that act as signaling  molecules The receptor is specific for a particular ligand (lock-and-key specificity) and produces a specific response in the cell (Receptor –ligand specificity) # between endocrine hormonal and neural signaling. Neurotransmitters + Are released into small packets at the synapse (functional connection between two neurons or neuron muscle cell, or neuron and gland) into the synaptic cleft → activating the receptor on the other side of the synapse + Action/transmission is restricted to receptors at the end of the synapse Endocrine hormones + Released into circulatory system + Actions on any cell in the body with a receptor for the ligand Key Noradrenaline (neurotransmitter) - NE neurotransmitters + Released by neurons of the sympathetic nervous systems and hormones to evoke fear, flight or fight responses involved in + Activates class of receptors called adrenergic receptors thermoregulation → increase heart rate, increase heat production (thermogenesis) ⇒ increase metabolic rate Adrenaline  + Secreted by adrenal gland (under sympathetic control) + Activates a class of receptors call adrenergic receptors Thyroid hormone + Secreted by thyroid gland, under hypothalamic regulation + Increases energy expenditure Sympathetic Thyroid nervous system hormones (T3 & (ANS) and T4) being endocrine system delivered in through the thermoregulation circulatory system → activates receptors inside the cell (thyroid hormone receptors) → activate pathways inside the cells → heat production Sympathetic nervous system (SNS) also activates adrenergic receptors → activates pathways → heat production ⇒ Both the endocrine pathway and ANS pathway increases thermogenesis (heat production) ❖ Describe what is meant by circadian rhythm, and apply this more broadly to understand of the dynamic nature of homeostasis What are circadian 24-hour cycles that are part of rhythms? the body’s internal clock, running to carry out essential background functions and processes. Circadian rhythms and the sleep-wake cycle Increased body temperature → wake up, falling body temperature → fall asleep Blood pressure lowest while asleep, increases to wake up Circadian rhythm and core body temperature Decline in core body temperature → sleep, rise in core body temperature → arousal and waking Homeostasis around the set point is not fixed, and we can oscillate naturally around a normal range (circadian rhythm) Correlation Decline in CBT → tiredness, dips in subjective alertness, mean between arterial pressure, dips in performance reaction time oscillations Rise in CBT → arousal and waking between core body temperature and sense of alertness / performance reaction time ❖ Explain the visceral reflexes involved in regulating core body temperature and describe how both hormonal and neural signalling chemicals are involved. Ways we exchange Radiation: heat with the heat given off via environment infrared (sunlight) Evaporation: tends to be cooling, transfers heat as water evaporates (sweat) Convection: heat exchange with surroundings (wind carrying heat away from the body, fans) Conduction: heat exchange with another object (koala on tree) Changes in blood flow to the skin (temp decrease = restrict, temp rise = increase), and sweat responses, help these systems (increasing heat loss or conserving heat to the environment) Physiological ❖ Metabolism thermoregulatory Non-shivering thermogenesis: responses + Increased energy use from cells (heat production through metabolism) + Both sympathetically regulated (adrenergic receptors) and regulate by endocrine system (thyroid hormones → adrenergic receptors) + Cold defense: conserve CBT, turn on nonshivering thermogenesis + Heat defense: lower CBT, switch off non-shivering thermogenesis Shivering thermogenesis: + Skeletal muscle rhythmically contracts to generate heat from muscle activity + Somatic (voluntary muscles) and endocrine regulation ❖ Skin blood flow: Sympathetic Cutaneous vasoconstriction (cold defense): decrease skin blood flow and skin body temperature → reduces skin-air temperature gradient Active vasodilation (heat defense): increase skin blood flow → heat loss to environment via convection, conduction, evaporation ❖ Sweating: Sympathetic neural control of sweating Elements of reflex pathway Reflex response to Reflex changes in responses are environmental more complex temperature (involves both somatic responses to thermal discomfort and visceral responses to protect CBT) Changes to ambient temperature → sensed by skin thermosensors → we are aware of thermal discomfort → afferent pathways into the homeostatic regulatory centres of the brain (unconscious reflexes → visceral responses) and higher centres of the brain (conscious → efferent pathway to behavioural response) Changes in core body temperature (stimulus) → sensed by thermoregulatory sensors in the hypothalamus (vùng dưới đồi) → afferent pathways into the homeostatic regulatory centres of the brain (unconscious reflexes) → evoke visceral responses to protect CBT independent to any changes in ambient temperature) ⇒ Cross-talk between somatic and visceral systems such that changes in ambient temperature are sensed and the visceral system evokes responses to protect the CBT (can take place without disruption to CBT) ❖ Describe how fever is an adaptive (survival) response to infection  ❖ Describe the reflexes involved in elevating core body temperature to produce fever. What is fever? Fever = altered temperature regulated “set point” higher than normal value (we are still homeostatically regulating it) Infectious agent (pyrogens contained) activates immune response → releases inflammatory mediators Stimulates production of prostaglandin (PGE2) (stimulated from inflammatory mediators): secret into the blood, then carried to the thermostatic center in the hypothalamus Alters neuronal activity in hypothalamus leading to altered set point ⇒ Drug use: NSAID (ibuprofen / aspirin) reduce fever by blocking the production of PGE2 Physiological Recall that cells are big protein factories benefits of fever + Proteins do the work of the cell + Protein shape = protein function Optimal operating range for bacteria is 37ºC: moving away from their optimal range (fever) → less effective at surviving by impacting protein function Viruses: human cells operate most effectively at 37ºC ⇒ fever shifting the CBT → slow virus replication (by slowing down cellular processes in our body) Activate or enhance immune response to infection Heat sensitive Certain immune proteins operate better at higher than activation of the normal body temperature immune system It is an adaptive advantage to have an immune system  optimized to work at a different temperature + Immune response is low activity during normal temperature + Immune response is selectively activated during infection (proteins involved operate better at higher temperature) Fever is not always Sepsis beneficial –uncontrolled inflammatory response Excess high temperature can lead to organ damage MODULE 4.2: THUNDERSTORM ASTHMA WHAT IS ASTHMA? ❖ Respiratory System: basic anatomy and physiology ❖ What is asthma? ❖ What is the burden of asthma? ❖ Immunology of asthma ❖ Triggers for an asthma attack ❖ Overlap of upper and lower airways disease Overview of the Goes from the respiratory system nose to the diaphragm (cơ hoành) The upper airway + The hair from the nose → larynx (thanh quản): a filter that trap large particles and prevent them from reaching more delicate part of lungs  + Occupy in both left and right chest cavities surrounding the heart and constricted by the rib cage Purpose: + Transfer oxygen from the environment to the red blood cells + Transfer carbon dioxide from the blood to the air + To regulate acid-base balance. The bronchial * Air sacs: túi system khí * Alveoli: phế nang * Trachea: khí quản * Bronchi: phế quản Conducting system of the airways that then causes asthma What is asthma? A disease of the conducting airways of the lung → variable airflow obstruction Take biopsy → Inflamed mucosa (inflammation) Wall remodeling: thickening of the basement membrane  (epithelium) Asthma ❖ Airflow obstruction physiology Measure the performance of the lungs in terms of breathing through spirometry Ask a person to do a forced expiration from a top of breath in to the bottom of breath out + Forced vital capacity (FVC): the accessible volume of the lungs for a person + The amount of air they can blow in 1 second (FEV1): around 70-80% or more of the forced vital capacity (healthy lungs) For asthma patients: + Reduced airflow on expiration (breathing out) + By convention: reduced FEV1 to ~250 → people having eosinophilic asthma Allergic and Eosinophils are very important cell mediating the non-Allergic pathology of asthma Activation The eosinophils can get to the airway and cause asthma pathways (eosinophilic inflammation) in two pathways: allergen specific and non-allergen specific pathways. ❖ Allergic activation pathway Allergens are breathe in (inhale) → land on respiratory epithelium (a type of ciliated columnar epithelium found lining most of the respiratory tract as respiratory mucosa, where it serves to moisten and protect the airways) → pick up by dendritic cells and presented to the naive T cells in the airways submucosa → stimulate the cytokines IL4 and IL13 → the B cells which produce IGE The B cells bind with the mast cells → mast cells become allergen receptors + Contain histamine and other mediators that are very potent constrictors of airway smooth muscle and secretagogues for mucus + Cause the recruitment of  eosinophils to the airway through the secretion of compounds IL5 → Mast cells and T-cells lead to eosinophilic recruitment of the airway ❖ Non-allergic activation pathway Fungi or other pollutants (cigarette smok) can cause non-specific / innate immune pathway activation. TSLP and IL33 + Activate innate lymphoid cells + Secrete IL-5 and IL-13 → leading to hypertrophy of airways smooth muscle (increased muscle mass) and recruitment of eosinophils to the airways → Importance of viruses as stimulus for secretion of IL33, TSLP and innate lymphoid cells Role of IgE (more IgE (allergic antibody → details below) response to allergen challenge): lowest serum concentration of all antibodies Bound to cells both in the blood (basophils) and in the tissue (dominantly tissue bound to FcεR1 on mast cells and basophils) FcεR1 receptor density is strongly correlated with: IL-4 concentrations and IgE concentrations. Asthma Biologics Asthma triggers Air Pollution: Indoor and outdoor Allergens: + House dust mite: the most common allergen for  perennial allergic rhinitis ( 30 to 50% of asthma cases in children, 85% of patients with asthma are sensitised to HDM…) + Grass pollens, Animal danders + Occupational allergens → the allergic antibody could be synthesized to common allergens (stimulate immune response system despite being harmless) Exercise Viral infections + Responsible for >80% of asthma admissions to hospital in children, 70% in adults + Most common is rhinovirus. Cigarettes Health impacts of bushfire smoke Seasonal allergens Late winter to early spring: Tree pollens (silver birch, olive tree, plane tree) Late spring to early summer: Grass pollens (ryegrass) Summer to early autumn: Grass pollens (Bermuda, bahia) Spring to early autumn: Weed pollens (Plantain, Paterson’s curse) → Allergy diagnosis: skin prick test Thunderstorm asthma epidemic in Melbourne Normally: grass pollens are too big to get into the lower airway (trapped by upper airway only cause fever) and cause asthma (filtered out by the upper airway) In humid environment / to water: grass pollens will burst and exclude particles that are much smaller to be able to reach the lower airway → asthma POLLEN, ALLERGY AND THUNDERSTORM ASTHMA ❖ What is pollen and how do you count it? ❖ The 2016 thunderstorm asthma event ❖ What is thunderstorm asthma? ❖ What’s happened since the 2016 event? What is pollen? Fine powdery substance produced by certain types of plants as part of their process of sexual reproduction Pollen contains the male gametes of conifers (pine trees etc.) and flowering plants Plants are immobile → developed other ways of distributing their pollen to ensure their male gametes or pollen grains reach a receptive female Wind pollinated: + Cryptic flowers (those that do not attract pollinators, not remarkable, not secrete nectar)  + Light pollen and can drift considerable distance + Large amounts of pollen: chances that pollen grains reach the receptive female are very low Animal pollinated: + Showy flowers (have nectar) + Sticky pollen (get trapped in the fur/ feathers and get carried away after the animal visit) + Small amounts of pollen Wind pollinated plants are the most concerned: large amount of pollen that the immune system get exposed to → associated with allergies (pasture grasses in Victoria) How to count Use a Burkhart spore trap (like a vacuum cleaner) sucks in pollen air through a small nozzle at a rate of 10 litres / minute (same amount of human breathe) Inside the machine is a glass microscope slide covered with a sticky substance → move across the nozzle over a 24 hour period → physically count the pollen grains on each slide The raw count is converted to a value for the average numbers of pollen grains per cubic meter of air for 24 hour period Translate into the rating in the Melbourne Pollen count app (low/ moderate/ high/ extreme) → manage allergies by taking antihistamines or staying indoor The 2016 10th wettest spring on record (pasture grasses across thunderstorm Victoria were high in productivity) asthma event November 1: First hot day of spring (temperature: mid-high 30s) → an ‘extreme’ grass pollen day Strong gusty northerly winds most of the day Early afternoon, a cool south-westerly change moved into the state North-south line of storms developed ahead of the change Gust front  hit Melbourne from about 5pm Temperature fell rapidly (low 20s) and humidity rose. After the gust of rain comes through, thousands of people have respiratory problems (difficult breathing) called ‘000’ for an ambulance → Largest epidemic thunderstorm asthma event What causes Triggered by a combination of high grass pollen levels and thunderstorm a certain type of gusty thunderstorm. asthma? (above) Role of the thunderstorm is to fragment the pollen What’s happened Eight monitoring sites distributed across Victoria since the 2016 Pollen monitored daily at 9am event? Observations and pollen forecasts sent to severe weather forecasters at BoM Thunderstorm asthma forecasts issued by Victorian Department of Health ALLERGY, IGE AND MAST CELLS ❖ Describe how mast cells are activated with particular reference made to activation in thunderstorm asthma (TA) ❖ Identify some of the mediators that are released from mast cells and the actions that they have ❖ Define the key role played by immunoglobulin E (IgE) and how it connects mast cell activation to allergens ❖ Describe the simple structure of an antibody ❖ Discuss the detrimental aspects of IgE and mast cells in the context of allergic disease ❖ Discuss the possible beneficial aspects of IgE and mast cells in host defense/immunosurveillance ❖ Discuss theories as to why the incidence of allergic disease is increasing. Describe how Called ‘mastzellen’- well fed cells: stained effectively with mast cells are chemical dyes activated with Granules: electron dense vesicles within its cytoplasm particular There are mediators in these granules (Histamine) reference made to The mast cell activated → degranulation: granules fuses activation in with the plasma membrane and disgorge their contents thunderstorm into the environment asthma (TA) Histamine then go and stimulate other cell types to produce symptoms of allergy + Cause a dilation of blood vessels → redness + Increase leakiness of blood vessels (local edema) → puffed up mucosa + Stimulate sensory neurons: itchiness → increase the risk of sneezing Describe the simple structure of an antibody Structure of common antibodies: Y shaped (FC and Fab part) Scientist tried to identify if it was an antibody (IgD, IgG, IgA, IgM) but none of these were possible ⇒ Finally found a unique type of antibody called immunoglobulin E (IgE) IgE characteristics Unlike other antibodies that tend to bind to the allergen, and when a few bind there’s kind of enough to interact with cells, the IgE is  sitting on the particular receptor of the mast cells (bound IgE with high affinity) → sensitize these cells, ready to respond rapidly should they encounter the allergen they have been raised against How IgE Histamine - connects mast cell contraction of activation to smooth muscle allergens? tissues of the lungs, uterus, and stomach. Cytokines - Th2 cytokines and particularly IL4 are responsible for switching the immunoglobulin synthesis by B cells to IgE production. Eicosanoids - Stimulate the production, recruitment, and activation of additional inflammatory cells, predominantly eosinophils. Why do we have A variety of mice models have been developed to mast cells? Are understand the they useful? role of mast cells Test on whether mast cell are protective for certain bacterial infections IgE is assumed to mediate some surveillance in anti-cancer actions Mast cells have shown to display a protective role to:  certain bacteria, certain viruses, parasitic worms, some cancers, HOST DEFENCE/Immune Surveillance Another study indicated the effectiveness in terms of the protective role of certain venoms → mast cells that provide efficiency in terms of survival → Mast cells play important protective roles in immune system, not as bad because they cause symptoms of allergy Why are allergic diseases on the rise? ❖ Hygiene hypothesis We no longer live in rural environments (in close contact with farm animals), we are using detergents and cleaning products to antimicrobial products… → less exposure to organisms that help direct and push our immune system in certain ways Therefore, our immune system starts producing T2 type of an immune response → generating IgE to sensitize  mast cells + triggering cells → allergic symptoms ❖ ‘Old friends’/ Microbiota hypothesis: We no longer have specific microorganisms / diversity of them in the environment, we are no longer exposed to these organisms → push the immune system into a sort of more protective and healthy direction. ❖ Epithelial Barrier Hypothesis: Damage of the integrity of the epithelium → permit greater entry of some microorganisms → triggers types of responses that drive chronic inflammatory symptoms of asthma PHARMACOLOGY, DRUGS AND THE TREATMENT OF ASTHMA ❖ The useful features of drugs as medicines ❖ Define the terms agonist and antagonist ❖ Describe drug binding to receptors to elicit effects ❖ Understand how different drugs can modify allergic inflammation The useful Effective: have the therapeutic action for which they are features of drugs indicated (for specific condition) as medicines Convenient: once a day tablet… Well-tolerated: few and manageable adverse (side) effects Safe: low risk of toxicity/drug allergy (consider current vaccine discussion – rare toxicity) Not too expensive How do Medicines (drugs) bind to proteins that are called medicines act in receptors the body? Agonists: drugs that stimulate the receptor protein function (action) Antagonists: drugs that bind to the active region of the receptor protein but do not stimulate the protein function (prevent action) Get the medicines in the body * Adrenal gland: tuyến thượng thận * Adrenal medulla: tủy thượng thận → Study different structure and closely related chemically (how chemical structure change over time) to optimize the features How does a receptor stimulant (agonist) convey a response to the cell? Get medicines Atropine: a xenobiotic antagonist binds to muscarinic from plants receptors and prevents the actions of the endogenous ( deadly agonist acetylcholine → as acetylcholine can cause muscle nightshade atropa spasms, this is ideal to use in terms of therapy/treatment. belladonna) Get medicines from HTS Glucocorticoids and 𝛽2-adrenoceptor agonists inflammation and airway obstruction A newer class of Monoclonal antibodies: antagonize the receptors by targeting biological towards the Fc portion of IgE, preventing IgE from binding to medicines mast cells  BASIC MANAGEMENT OF ALLERGIC RHINITIS AND ASTHMA Allergic rhinitis Symptomatic inflammation of the nose induced by allergen inhalation by sensitised individuals + Early/immediate allergic response (IgE crosslinking, degranulation, oedema) + Late-phase response (~4-8hrs post, nasal congestion) + Priming effect (worse on repeat) Diagnosis + Clinical history + Aeroallergen skin prick testing + Specific IgE testing / RAST Treatment + Minimisation / avoidance + Intranasal corticosteroids + Thunderstorm asthma education if rye grass pollen sensitized Asthma Triggers + Infections + Allergy + Irritants Diagnosis + History of recurrent wheeze and breathlessness, responsive to beta agonist (salbutamol) + Lung function testing to confirm Management + Preventers: inhaled corticosteroid to suppress airway inflammation  + Relievers: used as required to relaxed airway smooth muscle + Advanced treatments: monoclonal antibodies targeting IgE and eosinophilic inflammation, others + Best asthma care is medication adherence and avoidance of known trigger Climate change Climate change affects: and asthma Aeroallergen concentration + Increasing air temperatures and CO2 concentration associated with increased pollen production (faster and larger growth of plants) + Lengthening of pollen seasons Frequency of extreme weather events + Flooding, tropical cyclones: mold (nấm mốc) growth in homes + Thunderstorm frequency Impact + Greater exposure of aeroallergen leading to higher sensitisation rate + More frequent epidemic events + Other major cities may encounter similar environmental conditions MODULE 4.3: GASTROENTERITIS AND TYPHOID (viêm dạ dày ruột) Introduction to the gastrointestinal tract (GIT) and microbes Some specific examples of GIT pathogens: Brief overview of some mechanisms of pathogenesis Discussion/interview of developments in studying GIT pathogens OVERVIEW AND THE GASTROINTESTINAL TRACT ❖ Describe the role and structure of the gastrointestinal tract ❖ Identify the relationship between the immune system and the gut ❖ Define the arms of the immune system ❖ Understand the importance of balancing immune responses in the  gut The Covering the area from mouth to large intestines and gastrointestinal the bowels (GI) tract Part of the digestive system Open tube that is exposed to the external environment → not impermeable to prevent entry of microbes Important role in the uptake of material * Esophagus: thực quản Anatomically similar but can have different characteristics Specialized sections for uptake of different components + Small intestine: absorbing mainly nutrients + Large intestine: absorbing fluids Uptake in the The mucosal tissue GI tract is lined with mucosal tissue (selectively exclude or take up different outside components) The immune system and the gut There are something that don’t want to take in → immune system forms important role within the gut and GI tract The arms of the Innate immune system immunity: broad, short lived but rapid Adaptive immunity: specific, potential for memory but takes time ⇒ Both arms work together to carry out an effective immune response: innate immunity to quickly target and remove pathogens / bacteria (at the start) → adaptive immunity clear out those pathogens Balancing Immune responses need to be tightly regulated immune response Role for microbiota and trained immunity MICROBES AND GASTROENTERITIS ❖ Explain the differences between good and bad microbes in the gut ❖ Identify pathogenic traits of microbes that lead to gastroenteritis  ❖ Define gastroenteritis and the symptoms ❖ Describe the role of inflammation in gastroenteritis Microbes of the There are many different microbes that can line in the gut mucosal layer of the GI tract Some microorganisms sit within the gut and help with digestion Some cause damage to the host (salmonella): get enough nutrients → replicate → use host machinery to spread generic material Harmful ones need to find the right niche that allows them to occur without harming (stay inside the cell → shielding themselves from host defenses) Good types of microbes in the gut Regulating functions in the gut Different microbiota (diversity, number…) found in different tubes of the GI tract → depend on types of nutrients available and niches there Diversity of these also depend on the condition of the tissue (sick / healthy…) Bad types of microbes in the gut Pathogenic traits Promoting colonization in novel places (Niche settings of microbes of sterile locations - places that haven’t been occupied by) - urine / blood Antagonising host defenses: stop from working correctly Facilitating spread of other microbes Most will require a range of virulence factors + Needles that allow them to inject genetic material or protein into our cells → take control of host machinery + Producing different proteins that stop our immune cells from working Mechanism of infection Gastroenteritis Inflammation of the gastrointestinal tract Symptoms include diarrhea, vomiting, abdominal cramping (fever if its an infection) → loss of fluids Treatment involves rehydration therapy: most are self-limiting (disadvantaged countries don’t have access to resources to treat: drinking fluids, taking up salt…) Can be classified as infectious or non-infectious + As a result of the microorganism (cause damage themselves or produce toxins that affect mechanisms…)  + Caused by the host response (immune cells overreacting → damage) Inflammation 5 pillars that show the signs of inflammation: heat, and the gut redness, swelling, pain, loss of function Inflammation helps with immune responses but excessive can lead to damage → tightly control immune responses Inflammatory conditions → lots of molecules from immune system that tell blood vessels to dilate → lose tight junctions that keep cells together → Leaky gut + Easier for things to get in and out + Fluid leak from blood into the extra interstitial spaces where get the swelling SALMONELLA ENTERICA: DISEASE AND HOST IMMUNITY Salmonella Is a faecal-orally transmitted bacterial pathogen enterica Is a major food safety risk (undercooked chicken) Can be divided into more than 2500 subgroups known as serovars → cause infections in human and animals Global disease Human-restricted serovars (Typhi, ParatyphiA) burden of + No animal hosting infections caused between by pathogenic + Cause enteric fever serovars of (typhoid and paratyphoid Salmonella fever respectively) Non-typhoidal Salmonella (NTS) serovars (Typhimurium, Enteritidis) + Broad host range:  infected on colonize meat producing animals → passed to human (or reverse) + Cause gastroenteritis and Invasive NTS (iNTS) Disease Salmonella is ingested via contaminated food/ water → progression small intestine Salmonella comes to the gut lumen: + Anaerobic space, deplete of oxygen → fight for space and nutrients with normal gut flora (challenges) + Lumenal space provides extracellular niche for Salmonella growth + Interaction with other gut flora can affect disease pathology Some salmonella excreted into feces: become a source that contaminate other food / water → infect other people / animals Some salmonella stay in the gut and proliferate: at some point, salmonella begin the process of breaching the epithelial lining + Actively by infecting M cells and gain access to internal face of gut epithelial cells + Express a specific variant factors to infect epithelial cells + Passively captured by macrophages or dendritic cells ⇒ Whichever route it takes, crossing the gut barrier is a major bottleneck ⇒ Once crossed, it is quickly collected by local draining lymph nodes → into the bloodstream that cause sepsis and disseminate to other stereotypes (spleen, liver, bone marrow, gall bladder…) Systemic dissemination + Salmonella invades sites that would otherwise be sterile  + Predominantly grows in intracellular niche (Salmonella-containing vacuole - SCV) of infected cells → provide a physical barrier between salmonella and immune detection mechanism + Salmonella controlled by various host immune cells How does the The mode of recognition highlights different functions immune system of innate and adaptive immunity respond to salmonella? Control of Salmonella infection Requires both innate and adaptive immune responses THE ROLE OF BACTERIAL TOXINS IN GASTROENTERITIS Causes of There are many causes of gastroenteritis including gastroenteritis viruses, bacteria, parasites, chemicals and certain drugs Bacteria are a major cause of gastrointestinal illness Many different bacterial species are “enteropathogens” that cause gastroenteritis + Produce toxins that are responsible for the symptoms of gastroenteritis  + Strains that don’t make toxins often don’t cause disease + Bacterial toxin mediated gastroenteritis can be infectious (ingest pathogen → pathogen produce toxins within host → disease) or non-infectious (ingest preformed toxins → symptoms of disease, absence of enteropathogens) What is a Is a toxic substance produced and released by a bacteria bacterial toxin? that causes damage to another cell Bacterial toxins are usually proteins but not always Bacterial toxins come in many different shapes and sizes Bacterial toxins can damage different cells Bacterial toxins can damage cells in different ways Clostridiodes Is a difficile major hospital pathogen Causes gastrointestinal diseases known as C. difficile infections (CDI) ranging from mild diarrhoea to life-threatening pseudomembraneous colitis CDI is entirely toxin mediated: Toxin A, Toxin B, CDT (?) Strains that do not produce toxins do not cause disease Monoclonal antibodies targeting the toxins alleviate symptoms of disease Clostridiodes TcdA and TcdB are the major toxins produced by C. difficile toxins difficile within the colonic niche and disease Patients ingest spores of C. difficile → germinate and produce toxins within the gut → the toxins are taken up by colonic epithelial cells Once inside the cell the toxins target Rho-family GTPases (important signalling protein) ⇒ inhibition of  those proteins causing cell death The toxins cause extensive tissue damage, haemorrhage, inflammation of the gut and fluid accumulation leading to the onset of diarrhoea ⇒ the symptoms of disease associated with CDI are dependent on the presence of TcdA and TcdB Bacillus cereus Is an important cause of food poisoning It is a spore forming bacterium that is commonly found in soil, on vegetables and in many raw and processed foods It causes two different types of foodborne illness: Emetic (vomiting) and Diarrhoeal Symptoms are generally mild and resolve untreated within 6 – 24 hours Type of syndrome is dependent on the bacterial toxins produced by the causative strain + Emetic syndrome is a non-infectious illness + Diarrhoeal syndrome is a form of infectious gastroenteritis Bacillus cereus Emetic Syndrome: emetic toxin + Involves the ingestion of pre-formed emetic toxin also known as cereulide + It is a protein toxin that is resistant to heat, pH and proteolysis → ingestion of preformed toxin can lead to disease (in the absence of organism) Can survive cooking/ baking  Can survive passage through the stomach Exposure to cereulide leads to the destruction of mitochondria within intoxicated cells (toxins affect the mitochondrial membrane → destroy the cells → dies) Nausea and vomiting is caused by the binding and activation of 5-HT3 receptors: cereulide binds to 5-HT3 → hyperstimulation of the afferent vagus nerve (major nerve controlling stomach function) → nausea and vomiting Bacillus cereus Diarrhoeal Syndrome: infectious form of gastroenteritis enterotoxins + Involves the production of enterotoxins within the small intestine following ingestion of heat resistant B. cereus spores + Nhe–non-haemolytic enterotoxin + Hbl–haemolytic enterotoxin + Both enterotoxins are heat labile → Destroyed by cooking Both toxins are three- component toxins + Nhe–NheA, NheBand NheC + Hbl–L1, L2, B These three subunits associate with each other within the cell membrane → punch a hole / pore into the cell membrane → cell lysis and death (normally through the induction of caspase pathways) → disruption of the ileal barrier function → tissue damage, fluid accumulation and the onset of diarrhoea ⇒ The symptoms linked with the presence of those enterotoxins MODULE 4.4: MITOCHONDRIAL BIOLOGY AND DISEASE REVISION: ORGANELLE BIOLOGY Cells – the Chemical fundamental units level (atoms of life → molecules) → Cellular level → Tissue level → Organ level → Organ system level → Organism level Cell classification Both have DNA, plasma membrane, and ribosomes Components of Eukaryotic Cells Mitochondria Where sugar, fat, protein + O2 → energy (ATP) Function  + Generate energy through oxidative phosphorylation (OXPHOS) + Buffer Ca2+ + Fe–S cluster biogenesis + Regulation of cell death (apoptosis) + Immune signalling Endosymbiosis The Endosymbiotic Theory – describes how a large host cell and ingested bacteria became dependent each other for survival, resulting in a permanent relationship The nucleus may have formed from invaginations of the plasma membrane around the nucleoid of an ancient prokaryote Modern day mitochondria arose from an oxygen-breathing bacterium MITOCHONDRIA: RELICS OF THE BACTERIAL ANCESTOR Common Features of Mitochondria and Bacteria Ultrastructure of a Gram-negative bacteria bacteria Mitochondrial The features are very Membranes similar to the bacteria The mitochondria is divided into 4 subcompartments + Outer membrane + Intermembrane space + Inner membrane + Matrix: find mitochondrial DNA + ribosomes → ~ bacterial cytosol Mitochondrial Double stranded, DNA (mtDNA) supercoiled circular molecule 37 genes in human cells: 2 rRNA, 22 tRNA and 13 proteins Arranged in “nucleoids” mtDNA and proteins involved in replication and transcription Maternally inherited: di truyền theo dòng mẹ Multiple copies (heteroplasmy): not every mtDNA in a given cell is exactly the same Mitochondrial Ribosomes and Translation HOW DO NUCLEAR ENCODED PROTEINS GET TO THE  MITOCHONDRIA? Reduction in the There mitochondrial was an overall genome reduction in the mitochondrial genome over time: the organism that became mitochondria relinquished some of its control by transferring the majority of its genome to the nuclear genome Modern-day mitochondria contain ~ 1200 proteins but only 13 are encoded by mtDNA (the remainder are encoded in the nuclear genome) 13 proteins that maintained by mtDNA are components of mitochondrial electron transport chain Hypothesis: Electron transport chain consists of predominantly membrane proteins. These proteins are so hydrophobic that can put too much pressure on eukaryotic cell to produce them in cytosol and bring them to the mitochondria from the outside The life of a DNA → mRNA nuclear encoded (transcription) → protein mitochondrial (translation) precursor Nuclear encoded proteins are synthesized as “precursor” proteins on cytosolic ribosomes Precursor proteins have specific targeting sequences or “zip codes” (amino acids) that deliver them to mitochondria At mitochondria,  precursor proteins engage with machines called “translocases” → mediate entry into the organelle Mitochondrial Their Translocases function is to deliver the protein into the correct compartment) TOM: Translocase of the Outer Membrane TIM: Translocase of the Inner Membrane SAM: Sorting and Assembly Machinery of the Outer Membrane OXA1: Oxidase Assembly Protein 1 *SAM and OXA are conserved from bacteria Protein Transport in Cells The Proteome: mitochondrial the entire set of proteome proteins that is, or can be, expressed by a genome, cell, tissue, or organism at a certain time. Mitochondrial proteome: the entire set of proteins that is, or can be, expressed by the genome (including  mitochondrial genome) and is targeted to mitochondria CELLULAR RESPIRATION What is cellular The respiration? metabolic pathway that breaks down glucose and produces ATP: C6H12O6 + 6O2 = 6CO2 + 6H2O + ATP Three steps: Glycolysis, Citric Acid Cycle (Krebs cycle / TCA cycle), Oxidative phosphorylation Total of 38 molecules of ATP when the process is efficient (not every round will creates 38 ATP Glycolysis Occur in cytosol (tế bào chất) (có hoặc không có O2 đều xảy ra) Converts glucose to pyruvate Glucose (six-carbon sugar) undergoes a series of chemical transformations that results in glucose conversion to 2 molecules of pyruvate (three-carbon organic molecule) C6H12O6 → 2 C3H4O3 + 2 ATP + 2 NADH End products of glycolysis: 2 pyruvate, 2 ATP (4 in total but 2 ATP utilised during the process), 2 NADH, 2 H2O Each pyruvate molecule  travels to the mitochondrial matrix and is converted to a 2 carbon molecule Acetyl CoA (are oxidized by an enzyme complex called pyruvate dehydrogenase complex) 2 C3H4O3 → 2 Acetyl CoA (2C) + 2 NADH + 2 CO2 Krebs cycle (TCA cycle, Citric Acid cycle) Acetyl CoA is the starting point and is oxidized within 8 steps 2 Acetyl CoA → 4 CO2 + 2 ATP + 6 NADH + 2 FADH2 ⇒ End products after 2 rounds of TCA cycle (1 / Acetyl CoA) Oxidative Is a series of proteins and organic molecules found in Phosphorylation the inner membrane of the mitochondria (electron transport Electrons passed from one member of the transport chain) chain to another in a series of redox reactions Energy released in these reactions is captured as a proton gradient, which is then used to make ATP in a process called chemiosmosis (the movement of ions across a semipermeable membrane bound structure, down their electrochemical gradient) Together, the ETC and chemiosmosis make up oxidative phosphorylation. End products are: 32-34 ATP + 10 NAD+ + 2 FAD + 6 H2O Electron transport chain Electrons entered complex I / II through Ubiquinone to complex III → through Cytochrome c to complex IV Transfer H+ from matrix to IMS → create imbalance of H+ (proton-motive force) → H+ from IMS back to matrix → ATP The real electron chain Complex V  MITOCHONDRIAL DYSFUNCTION AND MITOCHONDRIAL DISEASE What is Long-term, genetic, often inherited disorders that Mitochondrial occur when mitochondria fail to produce enough Disease (Mito)? energy for the body to function properly Disease of energy production: Problems from ETC or other components Genetically and clinically heterogeneous: two mutations in the same gene can present with different clinical presentations → Poses a clinical challenge Any or all tissues can be affected Mutations in > 280 nuclear genes (or even mitochondrial mutations) linked to mitochondrial disease Affects 1 in 5,000 live births Severe condition in children (often fatal) Currently lack of effective treatments or therapies ⇒Any symptom, any organ, any age, any mode of inheritance Mutations leading to Mito: + Inherited from parents + Happen for the first time in a child (de novo mutations): during embryogenesis Clinical Features Mito principally affect tissues that are heavily reliant on oxidative metabolism + The central nervous system + Peripheral nerves, eye + Skeletal and cardiac muscle + Endocrine organs Many individuals with Mito have a multi-system disorder that often involves skeletal muscle and the central nervous system, but some individuals have a disorder that only affects one organ system Clinical Encephalopathy: disorder or disease of the brain presentations Neuropathies: nerve damage/dysfunction ‘Stroke-like’ episodes: ischemia (loss of blood flow)  + convulsions, visual abnormalities, numbness, hemiplegia (weakness on one side of body), and aphasia (language impairment) Myoclonic epilepsy: seizures, involving uncontrolled muscle contractions or twitching Ataxia: loss of muscle coordination (neurological) Dystonia: sustained muscle contractions (twisting, spasms etc, neurological) Myopathy: disease of the muscle, resulting in weakness Deafness and Blindness Lactic acidosis: anaerobic glucose metabolism → increase in blood lactate and decrease in pH Cardiomyopathy: disease of the heart muscle that makes it harder for your heart to pump blood to the rest of your body Adult and Childhood-onset mitochondrial diseases can be linked childhood-onset to both mitochondrial and nuclear mutations Mito Adult-onset mutations are often linked to mitochondrial mutations Classification Many other genes/processes (transcription, translation) / proteins (import) if mutations / not working properly are linked to mitochondrial diseases Primary mitochondrial disease (PMD): genes with a primary link to the function of the electron transport chain (including mtDNA mutations) Secondary mitochondrial disease (SMD): genes with an indirect function on the electron transport chain, or linked to another mitochondrial function MITOCHONDRIAL DISEASE DIAGNOSIS Mitochondrial ❖ Biochemical tests Disease Diagnosis Blood and urine samples as a first step: measurements of lactate and pyruvate in plasma, cerebrospinal fluid (CSF) and urine, measuring specific amino and organic acids → Hint perturbations / disturbances in metabolism → Can  be a reflection of dysfunctional mitochondria and mito Additional tests may be included: neuroimaging, electromyography (EMG) to measure muscle activity, and nerve conduction studies (NCS) ❖ Genetic studies of mitochondrial and nuclear DNA Replace muscle biopsies as the gold standard for diagnosis Very specific: identify mutations in a particular gene Expensive → requires a good deal of evidence that the cause of symptoms is mitochondrial ❖ Things to consider: Clinicians are using muscle and tissue biopsies less frequently for mitochondrial diagnosis because these tests may not be as comprehensive as genetic testing and may not be well tolerated by mitochondrial disease patients PMD and SMD cannot be differentiated with laboratory tissue testing alone Functional tests (evaluations of how mitochondria are functioning in cells) remain important measures of mitochondrial function. Advancements in genetic diagnoses  ❖ Genomic studies Extract DNA from blood sample Undertake different degrees of coverage in terms of sequencing of the genome Look for variation and interpret variation in genetic variants from databases + If specific genetic variants are identified as pathogenic based on prior evidence (in databases) → this could lead to established diagnosis + Novel variant or no likely caused identified, variant of uncertain significance → supplement with functional analysis of tissues ❖ Functional studies: Omics approaches allow us to hone in potential defects of mitochondrial Functional Studies in Biomedical Research The analysis of large amounts of data representing an entire set of some kind, especially the entire set of molecules, such as proteins, lipids, or metabolites, in a cell, organ, or organism Proteomics in Use the mass spectrometry to get fast evidence, disease diagnosis especially if genomics is proving to be challenging for  diagnosis Can facilitate downstream genomics and downstream genomic functional analysis MITOCHONDRIAL DISEASES LINKED TO MTDNA MUTATION Division of mtDNA MODULE 4.5: