BLG 311 Study Guide - Cardiac Surgery, Infection, Nanosecond

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coffeecoyote275

30 Apr 2012

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More than 85% of all cancers begin as precancerous lesions that are confined to the surface epithelium, which can be as thick as 500 m deep in human tissue. Two-photon imaging (tpi) is a powerful technique for the early diagnosis of epithelial cancers because it permits non-invasive imaging of sub- cellular features potentially hundreds of micrometers deep into tissue. Tpi can be used to distinguish cancerous and precancerous tissue from normal tissue down to 40 m deep. By attaching a fluorescent contrast agent to a non-fluorescent target of interest, tpi also has the ability to monitor a variety of additional bio-molecular signatures that are more strongly indicative of cancer. Microscope allows to study the dynamics of the immune system"s response to cancer and infectious diseases. Two-photon excited fluorescence differs from single photon excited fluorescence with regard to stage one of the three-stage fluorescence process.

Related Questions

Over years, a virus-infected cell slowly transformed into a cancerous cell exposing (due to mutations) changed antigens, i.e. proteins, on its cell surface. Which of the following cells of the immune system are most likely to recognize and attack this transformed cell?

A) tissue macrophages B) neutrophils C) natural killer (NK) cells

D) cytotoxic T cells

E) plasma cells

Scenario 5:
You are trying to image some structural feature or biochemical event within a thick tissue sample or within a restrained/anaesthetized small animal (e.g. a mouse). You need to achieve spatial resolution of ~10Î¼m to resolve cellular organization or signal from individual cells, and this needs to be at a depth of several 100 Î¼m, but imaging time is not a major limitation (the sample again is live although stationary). Issues to consider include limitations for imaging deep within a tissue sample and how image geometry and sample size affect which modalities can be used (i.e. tissue within an animal compared to isolated thick tissue sample)

The scenario describes commonly encountered problems in applying fluorescence microscopy to study biological samples. I would like you to discuss ways of overcoming the problems at hand.
-What is the cause of the fundamental limitation(s) present in the problem when using a conventional fluorescence microscope system (wide field microscope or regular confocal microscope)? What are the tradeoffs (e.g. photobleaching, acquisition speed, spatial resolution, signal, noise and background, or other factors) that provide practical limitations?

-What type of optical imaging approach, technology or strategy could overcome these problems?

-What light source, optical detector, fluorophore and other key instrumentation/reagents will be needed and why? (you may want to provide specs for specific products where relevant).

-How will this strategy work and how will it generate new information about the object/process being studied: e.g. will fluorescence intensity be measured, or fluorescence lifetime, or scattering, some other property?

-What other limitations could there be in the approach planned? Can these also be minimized and how?

tanbutterfly379

Scenario 4:
You are trying to image some biological event that occurs upon ~10ms time scale in a population of cells or tissue sample. This could involve measuring changes in membrane potential or calcium concentration, or rapid changes in some other biochemical event. The sample is of course live, and cellular (~5Î¼m) spatial resolution is required. The probes are generally reasonable bright but not sufficient that photobleaching and phototoxicity is not an issue. Issues to consider include acquisition time and the balance of signal collection efficiency and photo damage.

The scenario describes commonly encountered problems in applying fluorescence microscopy to study biological samples. I would like you to discuss ways of overcoming the problems at hand.

-What is the cause of the fundamental limitation(s) present in the problem when using a conventional fluorescence microscope system (wide field microscope or regular confocal microscope)? What are the tradeoffs (e.g. photobleaching, acquisition speed, spatial resolution, signal, noise and background, or other factors) that provide practical limitations?

-What type of optical imaging approach, technology or strategy could overcome these problems?

-What other limitations could there be in the approach planned? Can these also be minimized and how?

skycaribou976

BLG 311 Study Guide - Cardiac Surgery, Infection, Nanosecond

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