Bob Lewin

5 R's of Inflammation

1) Recognition of injurious agent.

2) Recruitment of leukocytes

3) Removal of agent

4) Regulation/control of response

5) Resolution/repair

Cardinal Signs of Inflammation

Heat- Calor

Redness- Rubor

Swelling- Tumor

Pain- Dolor

Loss of Function- Functio Laesa

Acute Inflammation

Onset: Fast- minutes or hours.

Cellular Infiltrate: many NEUTROPHILS.

Tissue injury, fibrosis: mild and self-limited.

Local and Systemic Signs: prominent.

Exudation: fluid and plasma protein.

Acute Inflammation Major Components- Vascular and Cellular Changes

1) Vascular Changes:

- Vasodilation: increased blood flow.

- Increased Vascular Permeability: plasma proteins can leave circulation

- Endothelial Cells Activated: Increased adhesion of leukocytes (WBC's) and migration through vessel wall.

2) Cellular Events:

- Emigration of leukocytes from circulation

- Accumulation in focus of injury (cellular recruitment)

- Activation of leukocytes to eliminate offending agent

- Principal leukocytes are NEUTROPHILS

What occurs when a microbe enters the tissue? Damage?

Macrophages and dendritic cells and mast cells sense an infection/damage and secrete cytokines (TNF IL-1 and CHEMOKINES) to induce and regulate the inflammatory response. TNF and IL-1 act on endothelial cells of VENULES adjacent to the infection site to induce expression of adhesion molecules (E-selectins are expressed) so leukocytes can be released.

Inflammatory mediators also produced by plasma proteins react with microbes/ injured tissue. Some of these mediators promote efflux of plasma and recruitment of leukocytes to site of injury. Activated leukocytes remove offending agents via phagocytosis.

Side effect: damage to normal host tissues.

Exudate

Inflammatory extravascular fluid with HIGH PROTEIN CONCENTRATION, CELLULAR DEBRIS.

Specific gravity > 1.020.

Implies significant alteration in normal permeability of small blood vessels in injury site.

**The exudate contains molecules and cells that are vital to support the healing process.

Transudate

Clear watery fluid made of water, salts and LOW PROTEIN CONTENT (mostly albumin). Caused by hydrostatic pressure.

Specific gravity < 1.012.

*No increase in vascular permeability

*Not usually associated with inflammation

*Its just any fluid that passed through a normal membrane as a result of imbalanced hydrostatic and osmotic forces.

Edema

Excess of fluid in interstitial or serious cavities (either exudate or transudate)

Pus

Purulent exudate. Inflammation exudate rich in leukocytes (neutrophils), dead cell debris, microbes.

What stimulates acute inflammation?

- Infections (bacterial, viral, parasitic), microbal toxins.

- Trauma (blunt, penetrating)

- Physical and chemical agents (thermal injury, burn, frostbite, irradiation)

- Tissue necrosis

- Foreign bodies (splinters, dirt, sutures)

- Immune reactions

Changes in vascular flow in inflammation

** INCREASED VASCULAR PERMEABILITY is the hallmark of acute inflammation.

1) Vasodilation- earliest manifestation of acute inflammation. First in arterioles, then capillaries in injury site. Increased blood flow causes heat and redness (erythema). Induced by HISTAMINE.

2) Increased permeability of microvasculature will lead to the outpouring of protein rich fluid into extravascular tissue. This increases the osmotic pressure of intertitial fluid and leads to more outflow of water from blood to tissues- exudate. The fluid accumulation in extravascular spaces = EDEMA.

3) This loss of fluid leads to increased viscosity of blood- the vessels will be packed with red cells and the flow will be slower. This is referred to as STASIS.

4) With stasis, leukocytes (neutrophils) will accumulate along the vascular endothelium (Margination). The leukocytes will stick to the endothelium and migrate through the vascular wall into interstitial tissue.

Toll-like Receptors (TLRs)

In plasma membranes and endosomes, and detect extracellular and ingested microbes. This recognition activates transcription factors that stimulate production of secreted and membrane proteins such as mediators of inflammation, interferons, and proteins that promote lymphocyte activation

Inflammasome

Recognizes dead cells. Triggering this eventually results in activation of IL-1, a mediator of leukocyte recruitment in acute inflammation.

Mechanism that causes increased vascular permeability - what happens to the blood vessel walls?

Histamine, bradykinin, leukotrienes, and other mediators to specific receptors will cause endothelial cell (blood vessel) to contract- short lived contraction. The contraction of endothelial cells will cause intercellular gaps in postcapillary venules- MAKES PORES IN VESSEL WALLS LARGER.

Then, cytokines (TNF and IL-1) will induce a more prolonged retraction of endothelial cells and the cytoskeleton will change.

Lymphatic vessels during inflammation

Lymph flow increases and helps to drain edema fluid, leukocytes, and cell debris from the extravascular space.

Leukocyte Recruitment/ Neutrophil Migration (steps)- EXTRAVASATION

1) Margination

2) Rolling

3) Adhesion

4) Transmigration and chemotaxis

5) Phagocytosis

6) Destruction of phagocytes

(each step is outlined below)

Margination

Leukocyte accumulation at periphery of vessels. Cytokines and other mediators activate endothelial cells to express adhesion molecules. Leukocytes loosely attach to these.

Rolling

Cells bind and detach to tumble on the endothelial surface.

Selectins (bind sugars) mediate this:

- E-selectin: endothelial cells

- P-selectin: platelets and endothelium.

They bind sialylated oligossacharides attached to glycoproteins on cells.

The endothelial selectins are usually at low levels or not present on unactivated endothelium, but they are up-regulated after stimulation by cytokines and mediators.

Adhesion

Leukocytes have integrins and endothelial cells have ligands.

Adhesion is mediated by integrins (glycoproteins normally expressed on leukocyte membranes) on leukocytes interacting with their ligands on endothelial cells.

The integrins will not adhere to their ligands until the leukocytes have been activated by chemokines (cytokines secreted by cells at sites of inflammation, displayed on endothelial surface). Chemokines will cause integrins to cluster together and convert to high affinity form.

Other cytokines (TNF and IL-1) activate endothelial cells to increase the expression of ligands for integrins. These ligands include ICAM-1 and VCAM-1.

Transmigration

DIAPEDESIS- leukocytes squeeze between cells at intercellular junctions. The chemokines produced in extravascular tissues drive the migration of leukocytes toward the chemical gradient. Occurs predominantly in VENULES

PECAM-1 is a cellular adhesion molecule on leukocytes and endothelial cells. It mediates the binding events needed for leukocytes to transverse endothelium.

After passing through the endothelium, leukocytes secrete collagenases to help them pass through vascular basement membrane.

Chemotaxis ?

The migration of cells toward attractant chemicals or away from repellants.

Exogenous (outside)- bacterial products

Endogenous (inside)- chemoattractants such as components of complement system, pdts of lipoxygenase pathway, and cytokines of the chemokine family.

*All chemotactic agents bind to g-protein coupled receptors on leukocyte surfaces. This activates phospholipase C and phosphoinositol-3 kinase which leads to increased cytosolic Ca, which activates GTPases, which polymerizes actin, which leads to movement of leukocyte via chomotaxis!!! (this is one form of leukocyte activation- for the other two see below)

Neutrophil time-span

Neutrophils predominate during 6-24 hours, and are then replaced by monocytes in 24-48 hours.

The early abundance of neutrophils respond more rapidly to chemokines and attach more firmly to adhesion molecules (selectins).

However, neutrophils are short lived- they die by apoptosis and disappear.

Progression of main component in acute inflammation

edema --> neutrophils --> monocytes --> macrophages

3 Diff Forms of Leukocyte Activation

1) Peptides, chemokines, or lipid mediators bind to G-coupled receptors. This signals transduction and cytoskeletal changes: increased integrin avidity, which leads to adhesion to endothelium, and chemotaxis, which leads to migration into tissues. MAIN FORM.

2) The microbe binds to Toll-like receptor and the cytokines bind cytokine receptor which produces mediators such as arachidonic acid metabolites and cytokines to amplify the inflammatory reaction. MORE ON THIS LATER.

3) Phagocytic receptor binds the microbe and cytokines bind cytokine receptor, leads to the production of reactive oxygen species (lysosomal enzymes) and initiates phagocytosis of microbe into a phagosome. This ultimately leads to microbicidal activity of leukocytes and the killing of microbes!!

What does leukocyte activation result in?

- Phagocytosis of particles

- Intracellular destruction of phagocytosed microbes and dead cells

- Liberation of substances that destory extracellular microbes and dead tissues.

- Production of mediators including AA metabolites and cytokines. These amp the inflammatory response by recruiting and activating even more leukocytes.

What happens after phagocytosis?

Neutrophils rapidly undergo apoptotic cell death and are ingested by macrophages.

Mast Cells

Release histamine, leukotrienes, enzymes, cytokines. Inflammation.

Macrophages

Secrete most of the cytokines important in acute inflammation. They are stationed in tissues to rapidly recognize injuries.

Vasoactive Amines

Histamine and serotonin are vasoactive amines that cause vasodilation and increased vascular permeability- first mediators released during inflammation.

Histamine- dilation of arterioles and increases permeability of venules

Serotonin- like histamine, in platelets, release is stimulated when the platelets aggregate after contact with collagen, thrombin, aDP, antigen complexes

Outcomes of Acute Inflammation

1. Resolution- Regeneration and repair

2. Chronic inflammation- can lead to restoration of normal structure and function or scarring

3. Scarring- fibrosis, loss of function

Cell Derived Mediators of Inflammation (overview)

Histamine- comes from mast cells, basophils, platelets. Causes vasodilation, increased vascular permeability, endothelial activation.

Serotonin- comes from platelets, causes vasoconstriction.

Prostaglandins- comes from mast cells and leukocytes. Causes vasodilation, pain, and fever.

Leukotrienes- comes from mast cells and leukocytes. Causes increased vascular permeability, chemotaxis, leukocyte adhesion and activation.

Platelet-activating factor- Comes from leukocytes and mast cells. Causes vasodilation, increased vascular permeability, leukocyte adhesion, chemotaxis, degranulation, oxidative burst.

Reactive Oxygen Species- Comes from leukocytes. Causes killing of microbes that are phagocytosed and tissue damage (high levels cause thrombosis and increased permeability, breakdown of ECM, and direct injury to other cell types).

Nitric Oxide (NO)- Comes from endothelium and microphages. Causes vascular smooth muscle relaxation, vasodilation and killing of microbes (cytotoxic agent).

Cytokines (TNF, IL-1, IL-6)- Come from macrophages, endothelial cells, mast cells. Locally cause endothelial activation (expression of adhesion molecules). Systemically cause fever, metabolic abnormalities, hypotension.

Chemokines- Come from leukocytes and activated macrophages. Cause chemotaxis and leukocyte activation.

Plasma Protein Derived Mediators of Inflammation (overview)

Complement- Comes from plasma (liver). Causes leukocyte chemotaxis and activation, direct target killing, and vasodilation (mast cell stimulation).

Kinins- Come from plasma (liver). Causes increased vascular permeability, smooth muscle contraction, vasodilation, pain.

Proteases (activated during coagulation)- Come from plasma (liver) and causes endothelial activation and leukocyte recruitment.

(more related to wound healing process)

Complement System

A group of about 20 plasma proteins that may amplify the inflammatory response, enhance phagocytosis, or directly lyse extracellular pathogens.

- Innate and adaptive immunity.

- Most abundant protein is C3.

Consists of the Classical Pathway (triggered by C1 activation), Alternative Pathway (continuously activated due to spontaneous C3 hydrolysis), and Lectin Pathway (activated by manose binding lectin (MBL) binding to mannose residues on pathogen surface).

*ALL THREE PATHWAYS GENERATE VARIANTS OF THE PROTEASE C3 CONVERTASE. This cleaves C3 into C3a and C3b, which stimulate histamine release from mast cells. Leukocyte adhesion, chemotaxis, activation, and phagocytosis are all influenced.

C5 convertase makes C5a which is important in promoting arachidonic acid metabolism in neutrophils and monocytes.

Arachnoid Acid (AA) Pathway

Produced when there is a tissue injury. Arachidonic acid is metabolized to produce inflammatory mediators (protaglandins and leukotrienes).

The Arachidonic Acid metabolites are called EICOSANOIDS and their major sources are leukocytes, mast cells, endothelial cells, and platelets.

There are two major pathways in AA metabolism- COX (stimulates synthesis of prostaglandins and thromboxanes) and LIPOXYGENASE (production of leuokrienes and lipoxins).

*MEMORIZE COMBOT PICTURE

Below in the next few cards are the metabolites (whats produced) of the AA pathway:

Prostaglandins and Thromboxanes

PGE2, PGD2, PGF2a, PFI2 (prostacyclin), and TXA2.

Platelets contain TXA2- platelet aggregating agent and vasoconstrictor.

Endothelial cells have prostacyclin synthase- PG12- vasodilator and inhibitor of aggression.

PDG2, PGE2, PGF2a- vasodilation and edema formation

PGE2- pain sensitivity, interacts with cytokines to cause fever.

Leukotrienes (LT)

Produced by 5-lypoxygenase, a major arachodonic metabolizing enzyme in neutrophils.

LTB4- potent chemotactic agent for neutrophils; produced by neurtophils and macrophages.

LTC4 and its metabolites- bronchoconstriction and increased permeability; produced in mast cells.

Lipoxins

In tissues, leukocytes change their major AA products from LT (leukotrienes) to lipoxins.

They are anti-inflammatory mediators that inhibit neutrophil chemotaxis and adhesion to endothelium.

Antagonists of LT.

Chronic Inflammation

Infiltration with mononuclear cells (MACROPHAGES, lymphocytes (T-cells), plasma cells). Monocytes differentiate into macrophages, which last several months-year.

Tissue destruction by products of inflammatory cells.

Repair- Angiogenesis (new vessel proliferation) and Fibrosis.

2 Major Pathways of Macrophage Activation

Classical (M1): Microbes and IFN-gamma activate the macrophage. This leads to ROS,NO, and lysosomal enzymes which have microbicidal actions such as phagocytosis and killing of bacteria. Or this leads to IL-1, IL-12, and chemokines which lead to inflammation.

Alternative (M2)- IL-13 and IL-14 activate the macrophage. This leads to growth factors and TGF-b to cause tissue repair and fibrosis. Or it leads to IL-10 and TGF-b which causes anti-inflammatory effects.

Lymphocytes

T and B lymphocytes migrate into inflammatory sites using adhesion molecule pairs and chemokines.

In tissues, B lymphocytes can develop into plasma cells that secrete antibodies.

CD4 T lymphocytes are activated to secrete cytokines. They recruit and activate macrophages as well as allow for more antigen presentation and cytokine secretion.

Cold Compresses

Cryotherapy.

1) Decreases local temperature

2) Decreases metabolism

3) Vasoconstriction of arterioles and capillaries (at first)

4) Decreased blood flow (at first)

5) Decreased nerve conduction velocity

6) Decreased delivery of leukocytes and phagocyte

7) Decreased lymphatic and venous drainage

8) Decreased muscle excitability

9) Decreased muscle spindle depolarization

10) DECREASED FORMATION AND ACCUMULATION OF EDEMA - due to vasoconstriction

11) Extreme anesthetic (insensitivity) effect

*Relieves pain (analgesic) because it decreases rate of nerve conduction or causes pain impulses to be lost or increases pain threshold by depressing nerve ending excitability.

Warm compress

Thermotherapy.

1) Increased local temperature

2) Increased local metabolism

3) Vasodilation of arterioles and capillaries, increased blood flow to part heated, increased leukocytes and phagocytosis.

4) Increased capillary permeability

5) Increased lymphatic and venous drainage

6) Increased metabolic wastes, increased axon reflex activity, increased elasticity of muscles ligaments and capsule fibers.

*Muscle relaxation

* Can be analgesic bc it makes your superficial layer of tissues hotter than tissue temperatures at the site of injury

Cold and Warm Compress

Altering cycles of short vasodilation periods followed by longer vasoconstriction periods can prevent local tissue injury caused by the cold.

Types of lip lacerations

Uncomplicated: extensive repair is not necessary, the key is to make sure there is accurate alignment of the anatomic structures. After alignment the laceration can be closed with sutures.

Complicated: Thru and Thru... repair begins with closure of vermilion border. Deep (polyglycolic) sutures are needed.

Thru and Thru Laceration

Signs and Symptoms: Significant hemorrhage due to abundant blood supply in fave and maxillofacial areas, visible defects, patient distress.

Normal Skin Histology

(COMBOT- be able to ID every picture)

types of epithelial tissue

Simple Squamous- one layer not perfect

Simple Cuboidal- one layer cubes

Simple Columnar- one layer, super long

Stratified squamous- multilayered, not perfect

Stratified cuboidal- layered cubes

Pseudostratefied columnar- layered and long

Transitional- multilayered and all different kinds.

Epidermis

"Come Lets Get Some Brunch"- Stratum corneum, stratum lucidum (only in thick skin), stratum granulosum, stratum spinosum, stratum basale (make up the epidermis). Top to bottom.

Mostly stratified squamous kertainized epithelium. Mostly keratinocytes.

Includes langerhan cells, melanocytes, merkel cells, keratin, lymphocytes ... be able to ID all in pics.

Basal Layer

Deepest layer of epidermis- right before dermis.

Mostly columnar or cubical keratinocytes that tend to have larger nucleus. Proliferation occurs here.

Melanocytes distributed among keratinocytes.

Lymphocytes are mostly here.

BRUNCH

Merkel Cells

Mechanoreceptors; act like synapses for dermal sensory axons

Spinosium

Polygonal keratinocytes attached to each other though desmosomes.

SOME

Granular

Flattened keratinocytes parallel to skin surface. Contain keratohyalin granules, keratin, lamellar bodies.

Darkly stained.

GET

Corneum

Top top layer of epithelium.

Hexagonal highly flattened eosinophilic keratinocytes. Mostly keratin matrix. Sheds from skin.

COME

Basement Membrane

The junction between epidermis and dermis.

Wavy - contributes to skins resistance to tears and shearing forces.

Rete ridges- downward projections.

Dermal papillae- upward projections.

Dermis

Middle layer of skin. Split into two parts:

Papillary Dermis- Fine, relatively small collagen fibers. Fibroblasts, dermal dendrocytes, mast cells, vessels, nerve endings

Reticular Dermis- Coarser, larger collagen fibers

Hypodermis

Also called a subcutaneous layer, this is a layer of *fat located under the dermis of the skin. The hypodermis helps to insulate, thermoregulate, store energy, and protect the body.

Adipocytes, high lipid content.

Connective tissue septa separate adipocytes. Has fibroblasts, dendrocytes, mast cells, sweat glands, blood vessels.

Oral Mucosa

1) Stratified squamous epithelium- oral epithelium.

2) Basement membrane

3) Lamina proproa

4) Dermis

(COMBOT pics)

Stratified Squamous Epithelium

Oral epithelium. It lacks a superficial layer of keratin or just has a super thin layer of keratin.

Nonkeratinized- soft palate, inner lips, inner cheek, floor of mouth, ventral surface of tongue

Keratinized- attached gingiva, hard palate, dorsal surface of tongue

Super sensitive.

Vermillion Border

area where the pink-red lip tissue meets the facial skin

vermillion border is pinkish red bc of the relatively translucent epithelium and blood in capillaries in the connective tissue papillae under the epithelium.

**This border lacks hair follicles and is dry due to lack of glands.

Ethics and Legal Responsibilities of Dental Student

?

Wound Healing - Phases and Timeframes

1) Hemostasis- stop bleeding (day 1-3)

2) Inflammation- New framework for blood and vessel growth (day 3 to 20)

3) Proliferation or Granulation- Pulls the wound closed (week 1 to 6)

4) Remodeling or Maturation- Final proper tissue (week 6 to 2 years)

PHASE I: Inflammatory Phase

PHASE 2: Granulation Tissue Formation

PHASE 3: Matrix Formation and Remodeling

Homeostasis Phase

Fibrin plug formation, release of growth factors, cytokines, hypoxia (deficiency in the amount of oxygen reaching tissues).

Involves

A) Vasoconstriction

B) Platelet Plug Formation

C) Coagulation

Vasoconstriction (haemostasis)

This is our initial response to vessel injury. The blood vessels contract to keep blood from gushing out. Cells around the injured area, especially endothelial cells, will begin to secrete signals telling smooth muscles of the blood vessels to contract. Our nerve reflexes then cause smooth muscle to contract.

Thromboxane A2 (TXA2) is produced locally at the site of injury via the release of arachidonic acid from platelet membrane - it is a potent constrictor of smooth muscles.

Endothelin synthesized by injured endothelium and Serotonin released during platelet aggression are also potent vasoconstrictors.

Bradykinin and Fibrinopeptides are vasoconstrictors as well.

Platelet Plug Formation (haemostasis)

PLATELET ADHESION: Injury to the intimal layer in the vascular wall exposes COLLAGEN to which platelets adhere. This process involves von Willebrand's factor (vWF) a protein in the sub-endothelium. The vWF in injured collagen binds to glycoprotein I/IX/V on the platelet membrane.

PLATELET RELEASE REACTION: After adhesion, platelets initiate a release reaction that recruits other platelets from the circulating blood to seal the disrupted vessel. ADP and serotonin are the principal mediators in platelet aggression. Arachidonic acid released from the platelet membranes is converted by COX to prostaglandin G2 (PGG2) and then to prostaglandin H2 (PGH2) which is converted to TXA2. TXA2 has potent vasoconstriction and platelet aggression effects.

PLATELET AGGREGATION: In a second wave of platelet aggression, a release reaction occurs where ADP, Ca 2+, serotonin, TXA2, and alpha-granule proteins are discharged. Fibrinogen is a required cofactor for this process, acting as a bridge for the glycoprotein IIb/IIIa receptor on the activated platelets. This release reaction results in compaction of platelets into a plug (irreversible). This causes alterations to occur in the phospholipids of the platelet membrane that allow calcium and clotting factors to bind to the platelet surface, forming enzymatically active complexes.

*Activated platelets express phospholipids (platelet factor III) and coagulation factor V, which are important in clot formation.

Coagulation (haemostasis)

Activation of thrombin and formation of fibrin.

INTRINSIC PATHWAY: Begins with factor XII and through a cascade of enzymatic reactions activates factors XI, IX, and VII in sequence. All the components that ultimately lead to fibrin clot formation are intrinsic to the circulating plasma and no surface is required to initiate the process.

EXTRINSIC PATHWAY: Requires exposure of tissue factor on the surface of the injured vessel wall to initiate the arm of the cascade beginning with factor VII.

*Activation of the extrinsic or intrinsic clotting pathway results in production of activated factor X (the two pathways CONVERGE), and activation proceeds in sequence of factors II (prothrombin) and I (fibrinogen). Clot formation occurs after proteolytic conversion of fibrinogen to fibrin.

Propagation of the clotting reaction ensues with a sequence of 4 enzymatic reactions, each of which involves a proteolytic enzyme that generates the next enzyme in the cascade by cleavage of a proenzyme and a phospholipid surface, such as a platelet membrane. Factor VIIa combines with factor IXA to form the intrinsic factor complex, which is responsible for the bulk of conversion of factor X to Xa. Factor Xa combines with factor Va, on the activated platelet membrane surface, to form the PROTHROMBINASE COMPLEX which is responsible for converting prothrombin to thrombin. Thrombin has multiple factors in the clotting process, such as conversion of fibrinogen to fibrin and activations of many factors (including XII which stabilizes the fibrin clot), as well as activation of platelets. Once formed, thrombin leaves the membrane surface and converts fibrinogen by two cleavage steps into FIBRIN (the clot) and two small peptides termed fibrinopeptides A and B.

*Calcium ion is needed for these cascades

Inflammation Phase

Platelets, macrophages, neutrophils. Involves cell recruitment, chemotaxis, and wound debridement.

- Complement cascade and neutrophil infiltration into wound site within 24-48 hours of injury.

- Leukocytes adhere to the adjacent blood vessels (margination) and actively move through the vessel wall via diapedesis.

- Macrophages appear 72 hours after injury- they are the main phagocytic cells. Fibroconnectin, elastin, and transforming growth factor beta 1 are all chemoattractants for monocytes.

(For more detail see inflammation slides above)

Proliferation Phase

Macrophages, fibroblasts, epithelial cells, endothelial cells, keratinocytes. RE-EPITHELIZATION.

Epiderma resurfacing, fibroplasia, angiogenesis, ECM deposition, contraction. Characterized by fibroblast migration, deposition of ECM and formation of granulation tissue.

Migration of keratinocytes. PDGF and TGF-beta attract fibroblasts to the wound, they proliferate and make a matrix of fibroconnectin. Fibroblasts make immature collagen, fibrilar collagen from the connective tissue in wound healing.

Maturation Phase

Fibroblasts, myofibroblasts.

Scar formation and release of fibrinogen fragments and other proinflammatory mediators. Longest phase involving continuous synthesis and breakdown of collagen as the ECM evolves.

Interaction of ECM and fibroblasts causes wound contraction and is influenced by multiple cytokines. ECM material is altered --> Type III collagen to Type I. The collagen matures and reorganizes.

Granulation disappears or evolves into a scar composed of less active fibroblasts, dense collagen, and fragments of elastic tissue.

Antibiotics (Classifications)

Classified according to the type of organism against which they are active:

- Antibacterial

- Antiviral

- Antifungal

- Antiprotozoal

- Antithelmintic

Antimicrobals (types and effect dependency)

Classified into:

1) Bacteriostatic- act primarily by arresting bacterial multiplication. Only inhibits bacterial proliferation while the host's immune system does the killing. Ex. Sulphoanamides, Tetracyclines, Chloramphenicol

2) Bactericidal- Act primarily by killing bacteria. Necessary for infections in patients with defective immune system (HIV, cancer, diabetes) and for overwhelming infections. Ex. Penicillins, Cephalosporins, Aminoglycosides, Isoniazid, Rifampicin.

The antimicrobial effect can be concentration dependent or time dependent:

- Concentration dependent: The outcome is related to the peak antibiotic concentration achieved at the site of infection in relation to minimum concentration necessary to inhibit multiplication of the organism (Minimum Inhibitory Concentration- MIC).

- Time dependent: Have more modest PAEs and exhibit time dependant killing; for optimal efficacy, their concentrations should be kept above MIC for high portion of the time between each dose.

*Chemotherapy = the drug treatment of parasitic infection in which the parasites are removed without injuring the host.

How Antimicrobials Act

Cell Wall- Bacterial multiplication involves breakdown and extensive of the wall. Interference with these processes prvents the organism from resisting osmotic pressures, so that it bursts. Ex. B-lactams (penicillins, cephalosporins, vanvomycin, bacitracin, cycloserine).

Protein Synthesis- Interference with build up of peptide chains. Ex. aminoglycosides, tetracyclines, macrolides (erythromycin and clindamycin)

Nucleid Acid Metabolism- These drugs interfere directly with microbal DNA or its replication or repair. Ex. quinolones, metroindazole, rifampicin (RNA).

Penicillins

Act by inhibiting the enzymes involved in the crosslinking of the peptidoglycan layer of the cell wall which protects the bacterium from its environment; incapable of withstanding the osmotic gradient between its interior and its environment, the cell swells and ruptures.

So, penicillins are bactericidal and effective only against multiplying organisms bc resulting organisms are not making new cell walls.

Aminoglycosides

Act inside the cell by binding to the ribosomes in such a way that incorrect amino acid sequences are entered into peptide chains. The abnormal proteins are fatal to the microbe.

Aminoglycosides are bactericidal and exhibit concentration dependent bacterial killings.

Tetracyclines

Interfere with protein synthesis by binding to bacterial ribosomes. Their selective action is due to higher uptake by bacterial than by human cells.

Bacteriostatic.

Macrolides (Erythromycin)

Erythromycin binds to bacterial ribosomes and interferes with protein synthesis.

Bacteriostatic, time dependent.

Quinolones

Act by inhibiting bacterial (but not human) DNA gyrase, so preventing the supercoiling of DNA, a process that is necessary for compacting chromosomes into the bacterial cell.

Bactericidal and exhibit concentration dependent killign.

Metronidazole

In abligate anaerobic microorganisms, metronidazole is converted to an active form by the reduction of its nitro group. This binds to DNA and prevents nucleic acid formation.

Bacteriostatic.

Gram- Positives Drugs

Nafcillin and Dicloxacillin provide excellent coverage of most gram positives and are not destroyed by penicillinases.

Cephalosporins are effective against most skin and skin structure infections.

Gram negative drugs

Third generations cephalosporins are effective agaisnt many gram negatives and are not destroyed by cephalosporinases. They penetrate the brain well.

Cephalosporins and penicillins may enhance the activity of aminoglycosides against gram negatives. The combination of ampicillin and gentamicin provides very good coverage of both gram positive and gram negatives.

Amoxicillin is frequently used for otitis media and other bacterial upper respiratory infections.

Anaerobes Drugs

Metronidazole or clindamycin cover most anaerobic bacteria.

Mouth anaerobes are adeqately covered by Penicillin.

Systemic Fungi Drugs

Amphotericin is the drug of choice for presumed fungemia. Systemic fungal infections occur most frequently in patients that have been on broad spectrum antibiotics that have destroyed their endogenous bacteria, allowing fungal overgrowth.

Mycoplasma Drugs

The macrolides (erythromycin, clarithromycin, azithromycin) treat presumed mycoplasm pneumonia, along with most other organisms that cause community acquired pneumonia.

Pseudomonas Drugs

Ticarcillin or ceftazidmine cover most gram negatives, including Pseudomonas, but fail to treat some gram positives.

Imipenem and meropenem have good activity against pseudomanas.

Lymph Nodes

Look at COMBOT diagrams- ID all of them.

Cleanse the lymph (filters via macrophages) and alerts the immune system to pathogens (via lymphocytes).

**Cancer infiltrated lymph nodes are swollen but usually not painful. This helps distinguish cancerous lymph nodes from those infected by microorganisms.

Lymphatic Flow

Lymph flows through a system of lymphatic vessels (lymphatics) similar to blood vessels. Begins with LYMPHATIC CAPILLARIES, which are associated with blood capillaries.

They converge to form COLLECTING VESSELS which often travel alongside veins and arteries and share a common connective tissue sheath.

The collecting vessels empty into LYMPH NODES. The lymph trickles slowly through a node, where bacteria are phagocytized and immune cells monitor the fluid for foreign antigens. It leaves the other side of the node through another collecting vessel, traveling on and often encountering additional lymph nodes before returning to the blood.

Eventually, the collecting vessels converge to form larger LYMPHATIC TRUNKS, each of which drains a major portion of the body. There are 6 principal trunks: jugular, subclavian, bronchomediastinal, intercostal, intestinal, and lumbar trunks.

The lymphatic trunks converge to form two COLLECTING DUCTS, the largest of the lymphatic vessels. The right lymphatic duct receives lymphatic drainage from the right upper limb and the right side of the thorax and head and empties into the right subclavian vein. The Thoracic duct drains all the body below the diaphragm, and the left upper limb and the left side of the head, neck, and thorax.

*No pump, low pressure and speed- mechanism of flow is rhythmic contractions of the lymphatic vessels themselves.

*Flow is one way, it collects from the tissue and always deposits at the subclavian veins of the heart.

Lymph Node Anatomy

Cortex- Contains nodules.

- Situated beneath the capsule and represents the compartment where most lymphoid follicles reside. Composed of primarily B lymphocytes and follicular dendritic cells.

- Received lymph from afferent lymphatics

- Contains subcapsular sinus immediately inside the capsule, which receives lymph from the afferent lymphatics. Theyre lined by a thin endothelium penetrated by reticulin fibers and processes of dendritic cells.

- The outer cortex is where the B cells and dendritic cells are.

Paracortex- lacks nodules

- the region between the cortex and medulla. Does not have precise boundaries but is distinguished due to lack of nodules. Contain T cells and dendritic cells from other tissues.

Medulla- has draining sinusoids next to the hilum. Has two major components: Medullary cords and mediullary sinuses.

- Grows in the form of cords- rich in lymph sinuses, arteries, and veins but contains only a minor lymphocytic component (mix of B and T cells).

- Each node usually has a slight indentation on one side.

- Germinal center cells are predominantly B lymphocytes known as follicular center cells (centroblasts and centrocytes or small and large cleaves and non-cleaved cells)

- Has mactrophages and follicular dendritic cells.

Lesions

Abnormal tissue found in or on organism.

CLASSIFIED AS:

1) Shape

2) Size

3) Space

4) Location

5) Name

6) Cancerous?

Primary skin lesions involve a variation in color or texture of the skin, they are the initial reaction to pathologically altered tissue.

Secondary skin lesions take place in primary lesion as result of infection, scratching, trauma.

Common terms- rashes, macules, patches, papules, plaques, nodules, vesicles, pastules, bullae, erosions, and ulcers.

Types of Lesions (listed out)

Primary:

Macule- flat, pigmented, circumscribed area less than 1 cm. Ex. freckle, flat mole

Papule- Solid, elevated, less than 1 cm, skin color or pigmented. Ex. wart, pimple.

Nodule- Palpable, circumscribed lesion. Larger and deeper than papule. Extends into dermal area. Ex. tumor.

Tumor- Sold, elevated, larger than 2cm, extends into dermal and subcutaneous layers.

Wheal- Elevated, firm, rounded, with localized skin edema (swelling). Varies in size, shape, color. Paler in the center, accompanied by itching. Ex. hives, bug bite.

Vesicle: Elevated, circumscribed, fluid filled, less than 0.5cm. Ex. shingles, chickenpox.

Pustule- Small, raised, circumscribed lesion that contains pus. Less than 1cm. Ex. acne, psoriasis.

Bulla- Vesicle or blister larger than 1 cm. Ex. second degree bur, poison ivy.

Secondary:

Excoriations- Linear scratch marks or traumatized abrasions of the epidermis. Scratch.

Fissure- Small slit or cracklike sore that extends into dermal layer. Caused by inflammation or drying.

Ulcer- Open sore or lesion that extends to the dermis and heals with scaring. Ex. basal cell carcinoma.

Wound Infection

Wounds that drain purulent (pus) material, with bacteria identified on culture. IDed by edema (swelling w fluid), erythema (redness), and tenderness. Bacteria alone doesnt constitute an infection bc large numbers of bacteria can be present normally.

Deep infections present with fever and leukocytosis.

Common symptoms: Exudate, induration (hardness, mass formation), erythema, fever, biofilm, bad smell, necrotic tissue, slough tissue (yellow, tan, green, brown; moist in appearance)

Keloid

Benign growths of fibrous tissue that grow beyond wound boundaries. Caused by an OVERPRODUCTION OF CONNECTIVE TISSUE. Exhibit increased ratio of Type 1 to Type 3 Collagen- mainly composed of Type 3 collagen.

Associated with negative wound healing factors such as infection, excessive tension, foreign bodies, repetitive trauma.

Possible Causes:

- Apoptosis deregulation (excessive scaring, inflammation, overproduction of ECM)

- Keloidal fibroblasts- compared to normal dermal fibroblasts, these have increased proliferation rates and produce too much ECM

- Aberrant expression of various growth factors. Increase numbers of local fibroblasts and prompt excessive production of collagen and ECM. TGF-B is overproduced and poorly regulated.

COMBOT- histology slides

Treatment of Keloids

Before it develops: silicon sheeting, pressure treatment, corticosteroid injections.

After establishment: steroid injection, corticosteroids reduce excessiev scaring by reduction of collagen synthesis, glucosaminoglycan synthesis, and a reuction in inflammatory mediators and fibroblast proliferation

Surgical excision- almost 100% recur after surgery though. Post surgery silicon sheeting and compression is used

Cryotherapy- liquid nitrogen affects the microvasculature and causes cell damage via intracellular crystals leading to tissue anoxia (?)

Laser Therapy- CO2 laser or pulse dye laser PDL- provides photothermolysis leading to microvascular throbosis. PDL treatment is associated with suppression of keloidal fibroblast proliferation as well as induction of apoptosis.

Radiation Therapy- Silicone sheets are thought to work by increasing the temperature, hydration and oxygen tension of the occluded scar, causing it to soften and flatten. Applied after surgery

Genetics and Ethnicity of Keloid Predisposition

The genetic predisposition to form keloids is found predominantly in people of African and Asian descent.

It is unlikely that a single gene is responsible in keloids. A more likely scenario involves the interaction of one or more genes or gene pathways and or environmental factors with the culminating effect being the precipitation of dermal fibrosis.

Scar (and steps of formation)

Depressed or elevated proliferation of connective tissue that has replaced inflamed or traumatized skin.

Scar maturation is associated with proportional increases in collagen Type 1 relative to collagen Type 3.

It forms after the formation of granulation tissue in wound healing.

STEP 1: Fibroblasts migrate to site of injury, and proliferation is triggered by cytokines and growth factors.

STEP 2: Extracellular matrix deposition and scar formation- the number of proliferating fibroblasts and vessels decrease. Fibroblasts progressively deposit increased ECM

STEP 3: Tissue Remodeling- degradation of collagen and ECM proteins by matrix metalloproteinase. Myofibroblasts begin in produce excessive collagen limited to the borders of skin injury- leads to hypertrophic scarring.

Cicatrix

AKA hypertrophic scars. Scars left by injured tissue healing. Fades over time.

Dysregulation in apoptosis results in excessive scarring, inflammation, and an overproduction of ECM components.

Demonstrate elevated expression of growth factors: TGFb, platelet derived, IL-1, IGF-1. This increases fibroblasts and prompt too much collagen production in ECM.

Hypervascularity and hypercellularity.

Age and Environmental Effects on Wound Healing

Delayed wound healing in the aged is associated with an altered inflammatory response, such as delayed T cell infiltration into the wound area with alterations in chemokine production and reduced macrophage phagocytic capacity. Delayed re-epithelialization, collagen synthesis, and angiogenesis have been observed in aged people also.

Stress causes a delay in wound healing... stress causes dysregulation of immune system mediated through the hypothalamic-pituitary-adrena and sympathetic-adrena medullary axes. Less inflammatory cytokines go to wound cite.

Diabetes causes impaired healing due to defective T cell immunity, defects in chemotaxis, phagocytosis...

Alcohol Consumption - Diminishes host resistance and is a risk factor for increased susceptibility to infection in wound. Also your defense mechanisms like cytokine release is hindered.

Smoking- delayed healing and complications that lead to infection. Also nicotine causes decreased bloodflow due to vasoconstriction.

Vitamins involved in Wound Healing

Vitamin C (ascorbic acid)- Collagen synthesis

- Hydroxylizes proline and lysin in preprocollagen.

- Scurvy- impaired wound healing. a disease caused by vitamin C deficiency characterized by swollen bleeding gums and opening of previously healing wounds.

Vitamin K- Needed for prothrombin (II, VII, IX, and X), which is a protein present in blood plasma which is converted into active thrombin during coagulation.

Vitamin A (Retinoic acid)- Increases inflammatory response in wound healing.

Trauma Head and Neck Exam

Head, eyes, ears, nose, oral cavity/throat, neck. Areas of concern regarding possible trauma injuries are checked for.

Inspection- visual exam of head and neck.

Ausculation- listening to sounds within the body for defects or conditions

Palpation/Percussion- to discover internal abnormalities

Radiographic Evaluation- panoramic or lateral oblique views.

Sutures (Stitches)

Promotes primary wound healing. May generate inflammatory response, interfere with wound healing, increase infection.

TWO TYPES:

1) Resorbable- Do not need to be removed, dissolve on their own within a week of being plaved.

2) Nonresorbable- silk/nylon, must be removed.

**Closure should be completed within 6-8 hours of injury but 24 hrs is okay for simple facial wounds.

Tonsils

Lymphatic nodules. Participate in immune response against inhaled or ingested foreign substances. Lie within oropharynx.

Function is to process antigens and present them to the germinal centers of the lymphoid follicles. This modulates both B and T cell populations within the tonsil in early childhood.

3 Types:

1) Pharyngeal- nasopharynx; no lymph, sinuses, or crypts.

2) Palatine- on either side of posterior oropharynx; contain crypts and lymphoid follicles

3) Lingual- dorsum of tongue; has lymphoid follicles, each w a single crypt

Tonsilitis

Occurs when your tonsils are infected, they swell. Most cases caused by viruses- strep throat is caused by streptococcus bacteria.

The major viral etiologies are Epstein-Barr virus, coxsackievirus A, adenovirus, Rhinovirus, and measles.

Antibiotics can treat tonsilitis caused by bacteria (but not those caused by virus).