ISB204_F10_Lecture07p

ISB204_F10_Lecture07p - Last Class Last Class • Immunity...

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Unformatted text preview: Last Class Last Class • Immunity Chapter 13a Chapter 13a • Infectious Disease Pathogens Are Disease­ Pathogens Are Disease­ Causing Organisms cause disease – Staphylococcus – Salmonella – Escherichia coli – Clostridium botulinum • Certain bacteria produce toxins that • • • Bacteria itself could serve as a toxin ~100,000 cases/year ~60 deaths/year • E. Coli O157:H7 – Shiga­like Toxin (Verotoxin) – Shigella dysenteriae • Shiga toxin • Inhibit protein synthesis • N­glycosidase, cleaves key RNA from – Enterohemorrhagic • HUS – Hemolytic­uremic syndrome – – – – ribosome Toxin attaches to renal endothelium Acute renal failure Disseminate intravascular coagulation Loss of red blood cells and thrombocytes Antibiotic Antibiotic • • • • Bactrim Septra Trimethoprim/sulfamethoxazole cotrimoxazole INCREASES VEROTOXIN PRODUCTION Pathogens Are Disease­ Pathogens Are Disease­ Causing Organisms – bacterial toxins – beneficial bacteria – antibiotics – antibiotic resistance • Viruses can damage the host cell as they leave the cell after replication or when incorporated into the cell’s chromosomes • Ebstein­Barr • CMV • HSV – – – – mononucleosis – Cytomeglovirus – Herpes Simplex HAV, HBV, HCV Inflammatory liver Leads to cirrhosis • Hepatitis Virus • Protozoans (single celled eukaryotes with defined nucleus) cause • • disease by producing toxins and enzymes Giardiasis (diarrhea that can last for weeks) Malaria, sleeping sickness, amebic dysentery • Fungi often cause disease by secreting • enzymes that digest cells Parasitic worms cause disease by releasing toxins, feeding off blood, or competing with the host for food – Tape worm (cestoda and eucestoda) – Ascaris – large round worm • Eggs – develop into larve in intestine • Go through the intestine wall and enter blood stream • Travel to lungs and develop further • 25% of the world has is infected Pathogens Are Disease­ Pathogens Are Disease­ Causing Organisms • Prions cause disease by causing normal proteins to become misfolded and form clumps Prions Prions • “proteinaceous infectious particle” • Stanely B. Pruisner (1942­), 1982 The most bizarre of all the infections agents discovered in the twentieth century – We are not absolutely sure of mode of transmission – Transmissible spongiform encephalopathies (TSE) • Prion Diseases TSEs TSEs • Scrapie • • Transmissible mink encephalopathy Chronic Wasting disease – Mule, Deer, and Elk – Sheep and goats TSEs TSEs • Scrapie • • Transmissible mink encephalopathy Chronic Wasting disease – Mule, Deer, and Elk – Sheep and goats • Feline spongiform encephalopathy • Bovine spongiform encephalopathy (BSE) – Mad Cows Disease Human TSEs Human TSEs • • • • • Creutzfeldt­Jakob disease (CJD) Variant Creutzfeldt­Jakob Disease (vCJD) Fatal familial insomnia (FFI) Gerstmann­Staussler­Scheinker syndrome Kuru – Early 1960s, Carleton Gajdusek – Transmitted by cannibalistic mourning rituals – Suggested that Kuru, scrapies and CJD are similar Human TSEs Human TSEs • vCJD • CWD – Variant cases involving humans that were confirmed to have digested animals confirmed to have BSE – Hunters eating diseased deer Hypothesis versus Theory Hypothesis versus Theory • Hypothesis – An interpretation of a practical situation or condition taken as the grounds for action – A tentative assumption make in order to draw out and test its logical or empirical consequences – A plausible or scientifically acceptable general principle or body of principles offered to explain phenomena • Theory CJD lead to discover of prions CJD lead to discover of prions • Stanely B. Pruisner – Patient died of CJD (1972) – 1:1,000,000 people over the age of 60 – 90% of patients die within 1 year – Early stages of disease: • Failing memory, behavioral changes, lack of – Progression of the disease: • Pronounced mental deterioration, involuntary movements, blindness, weakness in extremities, and coma coordination, and visual disturbances Typical protein production Typical protein production • DNA • RNA – Transcribed – Translated – Folds – Forms quaternary structures • Protein Protein­Only Hypothesis Protein­Only Hypothesis • Prion proteins exist in two distinct conformations (same protein different shape) – Good twin and the evil twin – Dr. Jekylls and Mr. Hydes – The Mr. Hydes can make the Dr. Jekylls transform • As Mr. Hydes accumulate they aggregate (gather together) form threads – kill cells Protein­only Hypothesis Protein­only Hypothesis • 1997 Pruisner gets Nobel prize in • Physiology and Medicine for discovering prions and establishing a new genre of disease­causing agents 1967: Alper T, Cramp WA, Haig DA, Clarke MC. Does the agent of scrapie replicate without nucleic acid? Nature. 1967 May 20; 214(90):764­766 Hypothesis versus Theory Hypothesis versus Theory • Hypothesis – An interpretation of a practical situation or condition taken as the grounds for action – A tenetative assumption make in order to draw out and test its logical or empirical consequences – A plausible or scientifically acceptable general principle or body of principles offered to explain phenomena • Theory Protein­Only Theory Protein­Only Theory Hypotheses for the origin Hypotheses for the origin Human Evolution Human Evolution • Given a particularlu unexplainable • phenomenon we look for answers in evolutionary scenarios “biological tradition of trying to explain aspects of an organism’s phenotype through the fitness advantage” – Phenotype is a physical characteristic of a genetic component – Fitness advantage = only fit survive • There are different sequences for the • • Prion Evolution Prion Evolution prion protein in our genome (polymorphisms) This has been a consistent feature of our evolutionary past Could – Imply that acquired prion diseases were and are common in our history – OR – Implies a legacy of our past cannibalism Hypotheses for the origin Hypotheses for the origin If we did cause it If we did cause it • Did we exacerbate the situation – The manganese connection • Inactivates normal function leading to – (Nazi Chemists as chemical nerve agent) abnormal (Mr. Hyde) conformation • Phosmet Organophosphate insecticide • Used extensively to control warble­fly in United Kingdom If we did cause it If we did cause it • Assumption that the disease is caused by the recruitment and aggregation of Mr. Hydes Disease Is Spread When a Disease Is Spread When a Pathogen Enters the Body Through Contact, Consumption, or an Animal Vector Infectious Diseases Remain Infectious Diseases Remain Cause for Concern old diseases are reappearing • New diseases are emerging, and some Infectious Diseases Remain Infectious Diseases Remain Cause for Concern • Mutations • Environmental changes Infectious Diseases Remain Infectious Diseases Remain Cause for Concern • Epidemiologists track diseases Biological Organisms and Biological Organisms and Products May Be Used As Biological Weapons • Anthrax is caused by a bacterium that forms resistant spores Biological Organisms and Biological Organisms and Products May Be Used As Biological Weapons • Smallpox is caused by a highly contagious virus Biological Organisms and Biological Organisms and Products May Be Used As Biological Weapons • Botulinum toxin is a potent poison – Clostridium botulinum – 1 gram of crystalline toxin could kill 1 million if aerosolled and inhaled – Blocks muscle contraction • Paralysis and respiratory failure Biological Organisms and Biological Organisms and Products May Be Used As Biological Weapons • HIV – Lentivirus ...
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