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NE 490 Stuff
Stuff that wasn't on Exam 1 and 2
| Question | Answer |
|---|---|
| What is the definition of cancer? | Categorized by uncontrollable growth and spread of abnormal cells |
| What are the different types of cancer? | Carcinomas: cells that cover internal and external body surfaces Ex: lung, breast, bladder, colon, prostate Leukemia: cancer of blood cells ex: Stem cells Lymphoma: cells in lymph nodes and tissues Sarcoma: cancer in supportive tissue ex: bones |
| Difference between benign and malignant tumors | Benign don't spread, but can crowd out healthy tumors Malignant will spread |
| What are germ cells? | Reproductive cells- sperm and ovary |
| What are the different types of effects from radiation? | Deterministic: has threshold, above threshold: increase severity Stochastic: no threshold, probability increases with dose |
| What types of cancers were popular with x-ray workers? | skin cancers and leukeima |
| What types of cancers were popular with Saxony pitchblade miners and uranium miners? | Lung cancers |
| What workers had bone cancers? | Radium: the dial painters and the people treated with radium salt (ankylosing spondylitis & tuberculosis) |
| What cancer did people who were treated with Thorotrast have? | Liver |
| What is a latent period? | Time period between irradiation and appearance of disease Leukemia 5 –15 years (shortest) Solid cancers possibly 10 -60+ year |
| What are the different risk models? | Absolute, relative |
| Describe absolute risk model | the chance of a person developing a specific disease over a specified time-period radiation induces cancers at some fixed number above the natural incidence |
| Describe relative risk model | compare risk in two different groups of people radiation increases the natural incidence at all ages proportional to spontaneous background rates (predicts a larger number of induced cancers in old age) |
| Describe time-dependent relative risk model | function of dose, age at exposure, time since exposure, gender, etc. (Favored by BEIR) |
| How do you calculate relative risk? | p(event when exposed)/p(event when non-exposed) |
| What is dose rate effectiveness factor? | the dose rate effectiveness factor by which cancer risks are reduced for low dose rate, 2-10 for animals, around 1.5-2 for humans |
| How is dose affected by cataracts? | The higher the dose, the less of a latent period before cataract development |
| How is high LET radiation affected by cataracts? | At high doses, RBE = 10 for neutrons At low doses, RBE = 50 for neutrons |
| Where do radiation induced cataracts typically develop? | in the posterior region |
| What is the typical latent period for cataracts based on dosage? | 2.5 –6.5 Gy -~8y 6.5 –11.5Gy -~4y |
| What is the threshold dose for cataracts? | ~2 Gy for threshold ~5-8 Gy for prolonged/fractionated exposure |
| What are the germ cell radiation effects for males? | It may take several weeks for rad symptoms to fully exposed, threshold for temp sterility is ~0.15 Gy, perm is ~6 Gy, no physical changes |
| Describe the germ cell for males. | Sperm, goes through several divisions before progress to spermatozoa (~10 weeks) |
| What are the germ cell radiations effects for females? | No gamete stem cells after birth, produced hormonal changes, similar to menopause, ~4 Gy is perm sterility |
| What is the difference between heterozygous and homozygous gene pairs? | 2 genes in pair are alike in homo, 2 genes in pair are unalike in hetero |
| What does the y chromosome do? | Determines sex |
| What is doubling dose? | dose of radiation, if given uniformly to an entire population, needed to double the spontaneous mutation rate |
| What are the different mutation types? | Mutation, somatic mutations, germline mutations |
| Describe mutation. | Any change in chromosome, genes, and DNA |
| Somatic mutation | not inheritable, occurs when the DNA of a non-reproductive cell is damaged radiation-induced somatic mutations affect only the exposed individual |
| Germline mutation | inheritable, occurs when the DNA of a reproductive cell (sperm or ovum) is damaged example effects include miscarriages, stillbirths, congenital defects, premature death (first year of life), chromosomal abnormalities, and cancers |
| What is the definition for single gene mutations? | DNA structural change Recessive mutations-require that the gene be present in duplicate to produce the trait (unless X-linked) Dominant mutations-require only one gene to produce the trait |
| What are the two heredity changes that are possible for radiation damage? | Gene mutations: dominant, recessive, sex-linked Chromosomal changes: too many or too few. chromosome aberrations Multifactorial |
| What were the conclusions from the megamouse study? | Radiosensitivity of different mutations varied significantly,only possible to speak in terms of average mutation rates, A substantial dose-rate effect in mice was observed, spreading out dose resulted in fewer observed mutations. |
| Other conclusions from megamouse study? | Male mice were more radiosensitive than female mice at low dose rates, almost all genetic burden is carried by males, Genetic consequences of a given dose were greatly reduced if time was allowed between irradiation and conception |
| Is there a signature lesion or mutation from ionizing radiation? | No, Radiation tends to affect the same mutations that are induced spontaneously |
| Is the number of mutations proportional to dose of radiation? | Yes |
| What are the developmental effects of radiation of an unknown child? | Lethal effects Malformations Growth disturbances |
| What is preimplantation? | up to 5th day in mice, 10th day in humans, most sensitive stage to LETHAL effects, 0.1 Gy and above is lethal, "all or nothing" effect |
| What is organogenesis? | Period where all of the major organs are being developed, end of preimplantation an lasts until beginning of fetal period, irradiation results in structural, congenital anomalies, greatest temp growth retardation |
| What is the fetal period? | 14th day onward in mice; or at about 6 weeks onward in humans, largest degree of perm retardation, Effects on kidneys, hemotapoietic system, liver, gonads |
| The dose response curve for radiation-induced mutations was linear with no threshold: T or F? | True |
| What does repair do? | spares late responding normal tissue preferentially, repair of sublethal damage |
| What does reassortment/redistribution of cells in the cell cycle? | increases acute effects, no influence on late effects, increases damage to tumor |
| What does Repopulation/Regeneration do? | spares acute responding normal tissue preferentially, no influence on late effects, danger of tumor repopulation |
| What does Reoxygenation do? | no influence on normal tissue responses, increases tumor damage |
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