Craniofacial Reconstruction Techniques Quiz

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Questions and Answers

What is the primary purpose of the Boyden chamber assay in an in vitro test of a chemical agent?

To assess the cytotoxicity of the chemical agent

To analyze gene expression in treated cells

To measure the rate of cell proliferation

To test the ability of cells to migrate across a membrane (correct)

Which characteristic distinguishes the acquired immune response from the innate immune response?

It is immediate and non-specific

It activates the complement cascade

It recognizes specific antigens (correct)

It involves the production of chemokines

What role do neutrophils play in the inflammatory response?

They release histamines to induce vasodilation

They migrate to areas of inflammation to ingest foreign substances (correct)

They assist in the repair of damaged tissues

They produce antibodies to neutralize pathogens

Which of the following is NOT a characteristic of the innate immune response?

Slow response time of 3-5 days Signup and view all the answers

Which type of barrier is skin classified as in the context of innate defenses?

Anatomic barrier Signup and view all the answers

What condition is characterized by the premature fusion of cranial sutures?

Craniosynostosis Signup and view all the answers

What is a potential consequence of craniosynostosis?

Increased cranial pressure Signup and view all the answers

Why are biodegradable devices preferred over metal ones for craniofacial implants in children?

Avoidance of growth interference Signup and view all the answers

What is the composition of Lactosorb as a plating system for CMF implants?

82% LA, 18% GA Signup and view all the answers

What is NOT a benefit of using biodegradable implants for craniofacial reconstruction?

Permanent structural support Signup and view all the answers

How many successful implantations of Lactosorb have been reported since its introduction?

Over 50,000 Signup and view all the answers

Which factor is NOT a characteristic of CMF biodegradable implants?

Intrinsic growth promotion in pediatric cases Signup and view all the answers

What aspect of biodegradable implants contributes to their ideal use in pediatric cases?

Tailored degradation correlating with healing Signup and view all the answers

What is the main function of neutrophils?

Phagocytosis Signup and view all the answers

Which chemical mediator attracts neutrophils to the site of inflammation?

Interleukin (IL-8) Signup and view all the answers

What role do macrophages play in the immune response?

They act as antigen presenting cells. Signup and view all the answers

What is a consequence of problematic biomaterials remaining in macrophages?

They can lead to clinical conditions like silicosis. Signup and view all the answers

How do body mechanisms ensure the termination of acute inflammation?

Through the action of chemical mediators like IL-1ra Signup and view all the answers

What occurs to monocytes when they arrive at the site of damage?

They become macrophages Signup and view all the answers

What happens during the respiratory burst in neutrophils?

They release reactive oxygen and nitrogen species Signup and view all the answers

Why is termination of inflammation important?

To prevent prolonged physiological changes that can harm tissue function Signup and view all the answers

What is the purpose of SDS treatment in the sample preparation process?

To denature proteins and impart negative charges Signup and view all the answers

Which membranes can proteins be transferred to during the protein transfer process?

PVDF and nitrocellulose membranes Signup and view all the answers

How does the separation of proteins occur during the transfer process?

Based on their molecular weight and charge Signup and view all the answers

What is the role of BSA in the membrane incubation process?

To prevent the primary antibody from binding unspecifically Signup and view all the answers

What causes the visible detection of bands in western blotting?

Color change induced by horse radish peroxidase Signup and view all the answers

What is the primary function of channel proteins in a cell membrane?

Facilitating the diffusion of ions Signup and view all the answers

Which of the following describes a function of microtubules in the cytoskeleton?

Maintaining cell shape and division Signup and view all the answers

What distinguishes secondary antibodies from primary antibodies in the context of protein detection?

Secondary antibodies help visualize the binding of primary antibodies Signup and view all the answers

What is the main role of T helper cells after activation?

Stimulate B cell growth and proliferation Signup and view all the answers

What type of glycoproteins do cytotoxic T cells express?

CD8 Signup and view all the answers

What primarily allows bacteria to resist host defense mechanisms after adhering to biomaterials?

Formation of a biofilm Signup and view all the answers

Why do granulocytes struggle to effectively neutralize implanted biomaterials?

Biomaterials are too large or chemically resistant Signup and view all the answers

What do plasma cells produce upon activation?

Soluble antibodies Signup and view all the answers

What is the potential consequence of constant granulocyte activation at the site of biomaterial implantation?

Exhaustion of granulocyte function Signup and view all the answers

How many antibodies can a mature plasma cell release per second?

2,000 Signup and view all the answers

What initiates the immune response to biomaterials after implantation?

Recognition of biomaterials as foreign entities Signup and view all the answers

What is the main function of cytotoxic T cells?

To lyse infected or cancerous cells Signup and view all the answers

Which molecules do T helper cells recognize?

MHC Class II Signup and view all the answers

What role does polysaccharide slime play in bacterial colonies associated with biomaterials?

Acts as a physical barrier to phagocytic cells Signup and view all the answers

What is the role of memory cells in the immune response?

To remember past antigens for future responses Signup and view all the answers

What form do antibodies take on the surface of B cells?

Both membrane-bound and soluble Signup and view all the answers

Study Notes

Polymer Structure

Polymers are structural entities composed of a fixed number of atoms repeated to form the polymer.
Examples include polyethylene (PE), poly(tetrafluoroethylene) (PTFE), and polystyrene (PS).

Molecular Weight

Degree of polymerization (n): the number of repeat units in a polymer, indicated by 'n' in the chemical formula.
Molecular weight of the polymer: total weight of the polymer.
Number average molecular weight (Mn): calculated using the following formula, M_n = Σ(N_iM_i)/ΣN_i, where N_i is the number of chains and M_i is the molecular weight of each fraction.
Weight average molecular weight (Mw): calculated using the following formula, M_w = Σ(N_iM_i²)/ΣN_iM_i, where N_i is the number of chains and M_i is the molecular weight of each fraction.
Polydispersity index (PI): ratio of the weight average molecular weight to the number average molecular weight (PI = Mw/Mn). A higher PI indicates a broader distribution of molecular weights.

Size Exclusion Chromatography (SEC)

Separation is based on differential partitioning between a mobile phase and stationary phase, with molecules separated based on size differences, with larger molecules exiting the column first.
The retention time of a molecule depends on the size of the molecule in relation to the pores in the porous stationary phase.
Larger molecules do not enter the porous stationary phase and therefore exit the column first
Used to measure the molecular weight distribution of a polymer sample.

Polymer Tacticity

Isotactic: R groups arranged on the same side of the polymer chain.
Syndiotactic: R groups alternate positions on either side of the chain.
Atactic: R groups are randomly arranged on the chain.

Polymer Linearity

Linear: end-to-end fashion - chains branching off the main chain.
Branched: chains branching off the main chain.
Cross-linked: adjacent chains are joined at certain points via covalent bonds, forming a three-dimensional network.

Copolymers

Random: two or more repeating units randomly distributed along the chain.
Alternating: two or more repeating units alternating along the chain.
Block: each type of repeat unit is clustered in regions along the chain.
Graft: homopolymer chains are attached to a different homopolymer main chain.

Polymer Synthesis (Polymerization)

Initiation (Free radical): a monomer is activated through a chemical reaction to form a free radical.
Propagation: monomers successively join the polymer chain, increasing its molecular weight.
Termination: destruction of the active site; free radical coupling
Addition polymerization: monomers join together, with no loss of atoms
Condensation polymerization: monomers join together, with elimination of a small molecule (water).

Polymer Crystallization

Percent crystallinity: the degree to which a polymer is crystalline.
Lamellar structure: basic unit of a polymeric crystal; polymer chains fold to form this structure.
Semi-crystalline: polymers that contain both crystalline and amorphous regions.
Amorphous: regions found outside the lamellar structures

Factors Affecting Crystallinity

Mer side group, large side groups prevent neighboring chains from coming close enough to form a crystalline structure.
Chain branching, branched polymers have a lower percentage crystallinity.
Tacticity, atactic polymers have a lower possibility of crystallizing than isotactic or syndiotactic polymers.
Regularity of mer placement in copolymers, alternating and block copolymers have a higher probability of forming crystalline regions.

Melting Temperature (Tm)

Only crystalline polymers can undergo melting at a specific temperature.
Below Tm, the crystalline regions of the polymers are highly ordered.
Above Tm, the polymer chains show random distribution.
Melting occurs when there are enough atoms or chain segments vibrating to result in overall chain motion.

Glass Transition Temperature (Tg)

Only amorphous polymers possess a glass transition.
Below Tg, the polymer material is glassy and brittle
Above Tg, the chains are mobile enough to produce a rubbery and elastic material

Thermal Analysis (e.g., DSC)

Differential scanning calorimetry (DSC): measures the difference in heat flow into a sample and a reference sample as a function of temperature, while both samples are exposed to a controlled temperature ramp.
Used for thermal characterization of polymers

Crystal Structures

The ratio of volume of atoms in a unit cell and total volume of unit cell is called Atomic Packing Factor

Point Defects

The creation of defects increases the entropy of the system.
Vacancies: vacant atomic sites in a structure
Self-interstitials: extra atoms positioned between atomic sites.

Defects in Metal Crystal Structures (alloys)

Substitutional solid solution: impurity B added to host A (Zn in Mg)
Interstitial solid solution: impurity B (smaller than host A) is added to host A (C in Fe)

Physical and Chemical Properties of Metals

Metals are reactive with air, water, and acids, and usually form cation oxides in the process.
Metals are strong, hard, and tough; have a high strength-to-weight ratio; and are solids at room temperature
Malleable and ductile.

Ceramics and Their Parameters

Cations are generally smaller than anions
R_cation/r_anion determines coordination number.
Coordination number = max allowable no. of anions that can surround a cation.
Preferred coordination numbers - 2, 3, 4, 6, 8

Crystal Structure of Ceramics

AX crystal structures: Both cations and anions have equal charge.

Defects in Ceramic Crystal Structures

Schottky defect: missing oppositely charged ion pairs in the correct ratio to maintain electroneutrality.
Frenkel defect: an atom or ion leaves its lattice position and occupies an interstitial site.

Carbon Based Materials (e.g. graphite)

Formation of pyrolytic carbon used for its blood compatibility and stability.
Plane of hexagonally arranged carbon atoms, Van der Waals interaction between the plane.
Fullerene : single/multi-walled carbon nanotubes (used in reinforces biomaterials for orthopedic applications)
Biosensors are used for monitoring neural activities.

Adsorption and Absorption

Adsorption: adhesion of molecules to a solid surface
Absorption: penetration of molecules into bulk materials

Hydrophillic and Hydrophobic Interactions

Hydrophobic: low affinity for water.
Hydrophilic: high affinity for water. Hydrophilic polymers tend to repel proteins.

Surface Charge

An ionizable group or charged ion in a solution attracts an oppositely charged solution species to the surface.

Surface Roughness

Greater roughness may promotes protein adsorption.

Surface Modification Techniques

Chemical Vapor Deposition (CVD)
Radiation Grafting/Photografting
Self-assembled monolayer (SAM)

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Description

Test your knowledge on the principles and applications of craniofacial reconstruction, particularly focusing on biodegradable implants and the immune response involved in the healing process. This quiz covers various aspects from inflammatory responses to specific materials used in implants. Challenge yourself to see how well you understand these medical concepts!