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Chapter 11 Medical Biotechnology Detecting and Diagnosing Human Disease Conditions Models of Human Disease • Identify diseases and test therapies before clinical trials in humans • Clinical trials: three phases • Phase I: safety studies- safe dose and how to administer the dose (ADME) • Phase II: few hundred patients for the purpose of testing effectiveness • Phase III: effectiveness compared to other drugs –involve thousands of patients often with different backgrounds and stages of illness throughout the country Detecting and Diagnosing Human Disease Conditions Models of Human Disease • Rat gene, ob, also found in humans therefore homologous • Codes for a protein hormone called leptin if missing leads to obesity • Found that treating obese children defected in this gene with leptin decreases their weight Detecting and Diagnosing Human Disease Conditions Models of Human Disease • Organism has 959 cells, 131 of them are destined to go through apoptosis • Study programmed cell death in this organism • Programmed cell death important to correct development of the fetus and improper cell death is implicated in: Alzheimers, Lou Gehrig’s, Huntington’s, Parkinson’s Detecting and Diagnosing Human Disease Conditions Models of Human Disease • Heart attack mice • Defect in cholesterol uptake Detecting and Diagnosing Human Disease Conditions Detecting Genetic Diseases Detecting and Diagnosing Human Disease Conditions Detecting Genetic Diseases • Testing for chromosome abnormalities and defective genes • Amniocentesis (Test at 16 weeks - karyotype) • Chorionic villus sampling (Test at 8 to 10 weeks - karyotype) Detecting and Diagnosing Human Disease Conditions Detecting Genetic Diseases • Testing for chromosome abnormalities and defective genes • Fluorescence in situ hybridization (FISH) • Fluorescence probes that are specific for chromosomes and/or genes • Spectral karotype Detecting and Diagnosing Human Disease Conditions Detecting Genetic Diseases • Testing for chromosome abnormalities and defective genes • RFLP (restriction fragment length polymorphisms) Detecting and Diagnosing Human Disease Conditions Detecting Genetic Diseases • Testing for chromosome abnormalities and defective genes • ASO allele-specific oligonucleotide analysis Detecting and Diagnosing Human Disease Conditions Detecting Genetic Diseases • Single Nucleotide Polymorphisms (SNPs) • One of the most common forms of genetic variation • Estimated that one SNP occurs approximately every 1,000-3,000 bp in the human genome • 99.9 percent of the DNA sequence will be exactly the same –> 80% of 0.1 percent variation will be SNPs • Most have no effect because they occur in non-protein coding regions (introns) • 10 pharmaceuticals donated millions in a collaborative partnership called the SNP Consortium Detecting and Diagnosing Human Disease Conditions Detecting Genetic Diseases • Identifying sets of disease genes by microarray analysis • Microarray created with known diseased genes or SNPs • DNA from a patient is tagged with fluorescent dyes and then hybridized to the chip • Binding of a patient’s DNA to a gene sequence on the chip indicates that the person’s DNA has a particular mutation or SNP Detecting and Diagnosing Human Disease Conditions Detecting Genetic Diseases • Protein Arrays • Chips contain antibodies • Apply blood from a patient • Proteins from disease-causing organisms can be detected Medical Products and Applications of Biotechnology The search for new medicines and drugs • Pharmacogenomics • Different individuals with the same disease often respond differently to a drug treatment because of differences in gene expression. Animation http://learn.genetics.utah.edu/content/pharma/intro / Medical Products and Applications of Biotechnology The search for new medicines and drugs • Oncogenes- genes that produce proteins that may function as transcription factors and receptors for hormones and growth factors, as well as serve as enzymes involved in a wide variety of ways to change growth properties of cells that cause cancer • Tumor Suppressor Genes – regulate oncogenes Medical Products and Applications of Biotechnology The search for new medicines and drugs • Personalized Medicine • BRCA1 or 2 – increases risk of developing breast cancer • But there are many other cases of breast cancer that do not exhibit this mode of inheritance • They SHOULD be treated differently (i.e. different chemotherapy!) Medical Products and Applications of Biotechnology The search for new medicines and drugs • Improving techniques for drug delivery • Factors that influence drug effectiveness • Drug solubility • Drug breakdown • Drug elimination • Microspheres – tiny particles that can be filled with drugs Medical Products and Applications of Biotechnology The search for new medicines and drugs • Nanotechnology and Nanomedicine • nanosensors that can monitor blood pressure, hormone concentrations, unblock arteries, detect and eliminate cancer cells Medical Products and Applications of Biotechnology Artificial Blood • Started testing of blood in 1980’s for HIV • However it is still not tested in poor, developing countries • There is a need for safe-blood • Possibilities: cell free solutions containing molecules that can bind to and transport oxygen; or blood substitutes such as Hemopure that is made from the hemoglobin of cattle • What does blood matching mean? Medical Products and Applications of Biotechnology Vaccines and Therapeutic Antibodies • Vaccines stimulate immune system • Also hope that vaccination may be useful against conditions such as Alzheimer’s disease or drug addiction • Using antibodies in some types of therapies: Development of Monoclonal Antibodies Gene Therapy How is it done? Gene Therapy How is it done? • Delivering the payload: viral vectors for gene delivery Gene Therapy Targets for Gene Therapy • Treating cystic fibrosis • Defective cystic fibrosis transmembrane conductance regulator (CFTR) • Normally it serves as a pump at the cell membrane to move electrically charged chloride atoms out of the cells • If cells can’t move chloride out, they absorb water trying to dilute the chloride in the cell • This leads to the production of THICK sticky mucus Gene Therapy Challenges Facing Gene Therapy • Reaction to the vector, an adenovirus, led to the death of Jesse Gelsinger • It raised more questions than answers: • Can gene expression be controlled in the patient? • How long will the therapy last? • What is the best vector? Animation Regenerative Medicine Growing cells and tissues that can be used to replace or repair defective tissues and organs Regenerative Medicine Cells and Tissue Transplantation • 50,000 Americans are diagnosed with Parkinson’s annually • Caused by a loss of dopamine-producing cells deep inside the brain • Leads to tremors, weakness, poor balance, loss of dexterity, muscle rigidity, reduced sense of smell, inability to swallow and speech problems • After 4 to 10 years the drugs become ineffective leading to a poor quality of life for the patient Regenerative Medicine Cells and Tissue Transplantation • Fetal tissue grafts • The basic idea is to introduce fetal neurons which can establish connection with other neurons • Over 100 patients have received such transplants-shown some recovery Regenerative Medicine Cells and Tissue Transplantation • Organ transplantation • 8 million surgeries are performed each year and about 4000 people die waiting • Autograft – transplanting a patient’s own tissue from one region of the body to another- ex. Vein from leg used in coronary bypass-organ transplants are between individuals and so must be checked for compatibility • Histocompatibility complex - >70 genes which produce tissue typing proteins (must match!) • There are many different types of MHC proteins (one group is called human leukocyte antigens or HLAs)- have been using immunosuppressive drugs but there are problems. Regenerative Medicine Cells and Tissue Transplantation • Organ transplantation • Xenotransplantation – transfer between species (pig to human) • University of Missouri scientists have produced cloned, knockout pigs that lack a gene called GGTA1 (or 1,3 galactosyltransferase) • The gene normally codes for a sugar that would be recognized as foreign by humans Regenerative Medicine Cells and Tissue Transplantation • Cellular therapeutics • Involves using cells to replace defective tissues to deliver important biological molecules • Encapsulate living cells into tiny plastic beads (biocapsules) • Capsule protects the cells from rejection but yet allows chemicals to diffuse out • Could be used in Type 1 diabetes therapy Regenerative Medicine Tissue Engineering • Replacement of tissues and organs by growing them in culture • So far skin grafts have been successfully engineered Regenerative Medicine Tissue Engineering • The telomere story • Usually 8 to 12,000 base pair units of the the repeating sequence 5’TTAGGG-3’. (think of plastic tabs at the end of your shoe lacesprevents unraveling) • A cell’s lifespan is affected in part by telomeres –each time a cell divides, telomeres shorten slightly-which leads to senescence! (aged cells!) • Telomerase repairs telomere length by adding DNA nucleotides to cap the telomere after each round of cell division Regenerative Medicine Stem Cell Technologies • The CDC estimates hat 3,000 Americans die every day from diseases that may one day potentially be treated by stem cell technologies • What are stem cells? Known as Pluripotent! Regenerative Medicine Stem Cell Technologies • What are stem cells? • Two major properties: • ES cells can self-renew indefinitely to produce more stem cells • Under the proper growth conditions, ES cells can differentiate into a variety of mature cells with specialized functions • Human ES cells avoid senescene in part because they express high levels of telomerase! Regenerative Medicine Stem Cell Technologies • Adult-derived stem cells do everything embryonic stem cells can do and remove the ethical issue of destroying embryos. • Amniotic-fluid derived stem cells • Reprogramming somatic cells Regenerative Medicine Stem Cell Technologies • Potential Applications of Stem Cells Regenerative Medicine Stem Cell Technologies • Questions that need to be answered: • Is there an “ultimate” adult stem cell that could turn into every tissue in the body? • Why do stem cells self-renew and maintain an undifferentiated state? • What factors trigger division of stem cells? • What are the growth signals (chemical, genetic, environmental) that influence the differentiation of stem cells? • What factors affect the integration of new tissues and cells into existing organs? Regenerative Medicine Cloning • Therapeutic Cloning and Reproductive Cloning Human Genome Project How was this done? Human Genome Project Revealed disease genes on all human chromosomes