Radioisotopes in biology
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Transcript of Radioisotopes in biology
RADIOISOTOPES IN
BIOLOGY
AYESHA ZAINAB BEG
14 MBT 007
CONTENTS
INTRODUCTIONHISTORYPHENOMENON OF RADIATIONRADIOISOTOPES IN BIOLOGYSCOPEDISADVANTAGESCONCLUSION
INTRODUCTION ISOTOPES
Having same atomic number (protons in nucleus) and different atomic mass ( proton + neutron) .STABLE ISOTOPES
Stable nuclei and do not undergo radioactive decay.RADIOISOTOPES
Unstable isotopes which through the process of the radioactive decay attain stability.
RADIOACTIVE DECAY Particles or electromagnetic radiation are emitted from the
nucleus of an unstable isotope.
Wilhelm Röntgen 1895, produced and detected X-rays Henri Becquerel, 1896 discovered Radioactivity
Marie and Perrie Curie, 1898 discovery of Polonium and Radium.
HISTORY
THE ATOM• Protons(P) in nucleus indicates the atomic
number(Z) of the element.• Central nucleus is of proton (P) and
neutrons(N) where atomic mass (A) is concentrated. [A= Z+N]
Atomic stability and radiation• Ratio of neutrons to proton determine the
stability of the elements
THE PHENOMENON OF RADIOACTIVITY
ELEMENTSWith low Z
With high Z
N/P
N/P
PN
CONT.. Isotopes having high Z are unstable as nuclear binding energy decreases for the protons. Instability of isotopes leads to radioactive decay. Radiatioactive decays are classified as
• Alpha (α), Beta (β),Gamma (ϒ) and X Ray radiation.
ALPHA
Heavy Charged particle
Most ToxicConstant energy per
particle
BETA
Light Charged Particle
Less toxicNegatively charged
Energy varies particle to particle
GAMMA/ X RAY
Electromagnetic Radiation
Toxicity same as βHighly penetrating
PENETRATION DIAGRAM
TERMS AND UNITS
• Half-life Time taken for the activity to fall from any value to half of that value• Biological half-life Time taken by half the amount of radioisotopic element to leave the
body.
• Bq- One disintegration per second (dps)
• Ci- Disintegration in 1g Radium (curie - 3.7x1010 disintegration per seconds)
• Sv - Amount of radiation that gives a dose in humans equivalent to 1Gy of X-ray (1Gy=100 rad; 1 rad = .01j/kg
Radioisotopes -exquisite sensitivityRadiotracing a processCompatibility with in vivo system Assays and Probe
RADIOISOTOPES IN BIOLOGY
TRACING , DETECTION AND ASSAYRADIOTRACERS
• For metabolic pathway elucidation
• Metabolic turn over time
• Pharmacological studies
AUTORADIOGRAPHY
• Detection and localization of radiation from a given object.
• Photographic emulsion- silver halide + gel
• Ionising radiation from radioactive object acts upon photographic emulsion to give latent image.
• Radioactive event- Dark silver grains• Uses- i. Detection on chromatogramii. Tissue/organ sections iii. DNA,RNA and protein studies
RADIOIMMUNOASSAY• Radioimmunoassay (RIA) is sensitive technique used to measure
concentrations of antigens by use of antibodies
• Principle: Competitive binding of radiolabeled Ag* and unlabeled Ag to a high-affinity Ab
A STEPS IN RIA
B. Determination of Uk
C. EXAMPLE
Historical perspective of 32 P & 35S - Hershey and Chase experimentUse of 32 P and 3H
MOLECULAR BIOLOGY
Probes and Labeling
Probes20-30 ntd*
End labeling5’ or 3’
MISMATCH CLEAVAGE ASSAY Radiolabelled synthetic RNA strands
• Method used to detect point mutation and genomic variations.
• Synthetic wild type isotopic RNA forms heteroduplex with cDNA of mutated gene
• RNAse cleaves to the mismatch points in
the heteroduplex
• PAGE analysis gives insight of the point mutations.
• Used in cancer research and vaccines production. eg. P 53 gene
Isotopic RNA
cDNA from mutated mRNA
Heteroduplex
RNAse
Proc. Natl. Acad. Sci. USA Vol. 87, pp. 7555-7559,Iternational Atomic Energy Agency
NUCLEAR MEDICINE AND CLINICAL ASPECT
•THERAPEUTIC RADIOPHARMACEUTICALS
• Efficacious therapy of diseases by noninvasive manner
• Radioisotopes – 131 I , 211 At, 192Ir
• Eg. Hyperthyroidism and cancers.
DIAGNOSTIC RADIOPHARMACEUTICALS
POSITRON EMISSION TOMOGRAPHY 3D image of functional processes in the body. •Radioisotopes and radio tracers - nitrogen-13 ,oxygen 15 ,fluorine- 18 Eg.18- FDG •Positron decay produces indirect gamma rays.
•Detection- Gamma camera in the scanner•USES
• Clinical diagnosis• Neuroimaging
RADIOTHERAPY
•RADISOTOPES- 60Co , 192Ir , 137Cs
•EXTERNAL BEAM RADIATION THERAPY
•INTERNAL BEAM RADIATION THERAPY(BRACHYTHERAPY)
EBRT
IBRT
CONVENTIONAL RI• Conjugation of Ab with
radionuclide• Eg. 90 Y , 131I, 161Tb
• AUGER THERAPY• 125 I, 177Lu
• Low energy electron (Auger Electrons) emission.
• Highly accurate, less damaging and applicable with non-internalizing Abs.
RADIOIMMUNOTHERAPY
ACCR ; Institut Laue-langevin
SCOPE
• EVOLUTIONARY AND ARCHELOGICAL SCIENCE- RADIODATING
• CRIMNOLOGY AND HISTORY- NEUTRON ACTIVATION ANALYSIS
• AGRICULTURE , ENVIRONMENT & ECONOMICS
Radiolabeled pesticides Crop improvement- BARC(2010) green gram, black gram, groundnut, jute
FROM WHERE DID THE ICE MAN COMMETH ?WHO
KILLED NAPOLEAN?
• Damage to environment and disposal problems.
• High cost for production of radioisotopes.
• Radiation induced mutations or other health issues.
• In assays or detections possibility of loss of native state of sample.
DISADVANTAGES
• Radioisotopes are aiding in the developmental researches and disease profiling.
• Radio tracing opened avenues for in-vivo processes’s elucidation
• Development of Molecular Biology
• In Nuclear medicine diagnostic and therapeutics radiopharmaceuticals aiding treatments by non invasive method.
CONCLUSION
THANK YOU!