Chapter 2 Lecture (Dr. Dobson) TEST 1

Question 1

Circulating DNA as Biomarker in Breast Cancer

Answer 1

• As the release of tumor-associated DNA (cell free DNA or cfDNA) into blood circulation is a common event in patients with cancer, screening of plasma or serum DNA may provide information on GENETIC AND EPIGENETIC PROFILES associated with breast cancer development, progression, and response to therapy.
• Quantitative testing of circulating DNA can reflect tumor burden, and MOLECULAR CHARACTERIZATION OF CIRCULATING DNA can reveal important tumor characteristics relevant to the choice of TARGETED THERAPIES in individual patients.
• Contrary to circulating DNA from blood that presents molecular changes in tumor DNA in real time, tissue biopsies can deliver only a spatially and temporally limited snapshot of the heterogeneous tumor.
• Analyses of circulating DNA might provide PROGNOSTIC AND PREDICTIVE INFORMATION and therefore advance personalized medicine.
• The release of cfDNA into the Bloodstream occurs by different sources, including the Primary Tumor, Tumor Cells that circulate in Peripheral Blood, Metastatic deposits present at distant sites, and normal cell types, such as HEMATOPOIETIC and STROMAL Cells.
• Thus, BOTH Tumor and Normal cfDNA Circulate in the Bloodstream of patients with Cancer. Its rapidly INCREASED Accumulation in Blood during Tumor Development is caused mainly by an EXCESSIVE DNA release by APOPTOTIC AND NECROTIC CELLS!!!!!!

Question 2

Pathology Building Blocks

Answer 2

• Cells, tissues, organs disease
• Use all tools at your disposal ——-> microbiologic, immunologic, molecular, physiologic, pharmacologic
• Use this information in MOD and apply to systems pathology year 2

1) Etiology (cause)
2) Pathogenesis (sequence of events)
3) Morphology (structural alterations)
4) Clinical manifestations or functional derangements

Question 3

Example - Colonic Adenocarcinoma

Answer 3

• The combination of MOLECULAR EVENTS that lead to Colonic Adenocarcinoma is heterogeneous and includes genetic and epigenetic abnormalities. At least two genetic pathways have been described.
• Epigenetic events, the most common of which is Methylation- induced gene SILENCING, may enhance progression along either pathway.

Question 4

Breast Cancer

Answer 4

• Breast Cancer is associated with different Genetic and Epigenetic events, such as DNA Strand Integrity, Gene Amplifications, Gene Mutations, DNA Methylation, and Microsatellite Abnormalities

Question 5

Pathology —> The Study of “Disease”

Answer 5

• Virtually all forms of disease start with molecular or structural
alterations in CELLS.

• Injury to cells and to extracellular matrix ultimately leads to TISSUE AND ORGAN INJURY, which determines the morphologic and clinical patterns of disease.
• First we have to have some understanding of the normal cellular response to stress and noxious stimuli.

Question 6

cellular Responses to Stress and Toxic Insults

Answer 6

1) Adaptation
2) Injury
3) Death

Question 7

Adaptation

Answer 7

A) An organ (Organism) is in a state of HOMEOSTATIS until it is “STRESSED”

B) There is a functional or structural response to changes in Physiologic State or Pathologic Stimuli

C) HYPERTROPHY,

• HYPERPLASIA
• ATROPHY
• METAPLASIA

D) Uterus Hypertrophy in Pregnancy

• ENDOMETRIAL Hyperplasia from Estrogen
• Muscle Atrophy from Disuse (Cast)
• Goblet Cell METAPLASIA in Barrett Esophagus

Question 8

Cell Injury

Answer 8

• If the limits of Adaptive Responses are exceeded or if cells are exposed to Injurious Agent or stress, Deprives of essential Nutrients, or become compromised by MUTATIONS that affect essential Cellular Constituents, a sequence of events follows that is termed Cell Injury

a) Hypertrophy (Adaptation):
- Requires gene Activation, Protein Synthesis and New Organelles

b) Cell Injury:
- From DECREASED Blood Flow due t Atherosclerosis

c) Cell Death:
- Myocardial Infarction
* ** Cell Death can be due to Ischemia, Infection, Toxins

Question 9

Cellular Adaptations to Stress

KEY CONCEPTS

Answer 9

1) HYPERTROPHY: INCREASED CELL AND ORGAN SIZE, often in response to increased workload; induced by growth factors produced in response to mechanical stress or other stimuli; occurs in tissues incapable of cell division
2) HYPERPLASIA: INCREASED CELL NUMBERS in response to hormones and other growth factors; occurs in tissues whose cells are able to divide or contain abundant tissue stem cells
3) ATROPHY: DECREASED CELL ADN ORGAN SIZE, as a result of decreased nutrient supply or disuse; associated with decreased synthesis of cellular building blocks and increased breakdown of cellular organelles
4) METAPLASIA: CHANGE IN PHENOTYPE OF DIFFERENTIATED CELLS, often in response to chronic irritation, that makes cells better able to withstand the stress; usually induced by altered differentiation pathway of tissue stem cells; may result in reduced functions or increased propensity for malignant transformation

Question 10

Causes of Injury

Answer 10

• Oxygen deprivation (hypoxia/hypoxemia)
• Physical agents
• Chemical agents/drugs
• Infectious agents
• Immunologic reactions
• Genetic derangements
• Nutritional imbalance

PREVENTATIVE MEDICINE:

• Is the specialty of MEDICAL Practice that focuses on the Health of Individuals, Communities, and DEFINED Populations.
• Its goal is to Protect, Promote, and Maintain Health and well- being and to prevent Disease, Disability, and Death

Question 11

Necrosis

Answer 11

• The Morphologic appearance of Necrosis as well as Necroptosis is the result of DENATURATION OF INTRACELLULAR PROTEINS and Enzymatic Digestion of the Lethally Injured Cell (May see under the Microscope or in the Blood)

NECROSIS

a) Feature:
- ENLARGED (Swelling)

b) Cell Size:
- Pyknosis —–> Karyorrhexis ———-> Karyolysis

c) Plasma Membrane:
- DISRUPTED

d) Cellular Contents:
- Enzymatic Digestion; May LEAK OUT OF CELL

e) Adjacent Inflammation:
- Frequent

f) Physiologic or Pathologic Role:
- Invariably Pathologic (Culmination of Irreversible Cell Injury)

Question 12

Distinct Patterns of Necrosis

Answer 12

1) Coagulative Necrosis
2) Liquefactive Necrosis
3) Gangenous Necrosis
4) Caseous Necrosis
5) Fat Necrosis

Question 13

Caseous Necrosis

Answer 13

• Caseous [ka ́se-us], Caseation [ka′′se-a ́shun]

• Type of necrosis associated with infection Tuberculosis
(MYCOBACTERIUM TUBERCULOSIS)

• Described as Yellow-White and “CHEESE-LIKE”
• On microscopic examination, the necrotic area appears as a structure less collection of fragmented or lysed cells and amorphous granular debris enclosed within a distinctive inflammatory border; this appearance is characteristic of a focus of inflammation known as a GRANULOMA.

Question 14

What are the Mechanisms leading to Cell Injury?

Answer 14

• The cellular response to injurious stimuli depends on the NATURE of the injury, its DURATION, and its SEVERITY.
• The consequences of cell injury depend on the TYPE, STATE, and ADAPTABILITY of the Injured Cell.
• Cell injury results from different biochemical mechanisms acting on several ESSENTIAL CELLULAR COMPONENTS.

Question 15

Principal Biochemical Mechanisms and Sites of Damage in Cell Injury

Answer 15

1) MITOCHONDRIAL DAMAGE:
a) DECR ATP
- Multiple Downstream Effects

b) INCR ROS
- Damage to Lipids, Proteins, DNA

2) ENTRY OF CA2+
a) INCR Mitochondrial Permeability

b) Activation of Multiple Cellular Enzymes

3) MEMBRANE DAMAGE:
a) Plasma Membrane
- Loss of CELLULAR COMPONENTS

b) Lysosomal Membrane
- Enzymatic DIGESTION of Cellular Components

4) Protein Misfolding, DNA Damage
a) Activation of PRO-APOPTOTIC PROTEINS

Question 16

Mitochondrial Damage

Answer 16

1) DECREASE IN ATP:
- Reduction in ATP Levels is the fundamental CAUSE OF NECROTIC CELL DEATH!!!!!!!

• The Major cause o ATP Depletion are REDUCED SUPPLY of OXYGEN and NUTRIENTS, Mitochondrial Damage, and the actions of some TOXINS (Ex: CYANIDE)
• The Pores that develop and can release Mitochondrial Proteins is BLOCKED BY CYCLOSPORIN (Anti-Rejection Drug)

2) INCREASE in ROS:
- Antioxidants (Vitamin A and E) help REMOVE Free Radicals

• Binding of FREE IRON and Copper to Storage and Transport Proteins prevents Generation of ROS’s

Question 17

Entry of Ca2+

Answer 17

• And Injurious Agent (ISCHEMIA and TOXINS) can cause ENTRY of Extracellular Ca2+
• Entry of Ca2+ causes INCR Mitochondrial Permeability and an ACTIVATION of Multiple Cellular Enzymes

Activation fo Multiple Cellular Enzymes:

1) Phopsholipases
2) Proteases
3) Endonucleases
3) ATPase’s
4) Caspases

Question 18

Membrane Damage

Answer 18

• Early loss of Selective Membrane PERMEABILITY, leading ultimate to OVERT MEMBRANE DAMAGE, is a Consistent feature of most forms of Cell Injury (Except Apoptosis).
• Membrane damage may affect the Functions and Integrity of all Cellular Membranes

MECHANISMS of MEMBRANE DAMAGE:

1) Reactive Oxygen Species
2) Decreased Phospholipid Synthesis
3) Increased Phospholipid Breakdown
4) Cytoskeletal Abnormalities

Question 19

What are the Mechanisms leading to Cell Injury?

Answer 19

• Cells have mechanisms that repair damage to DNA, but if DNA damage is too severe to be corrected (e.g., after exposure to DNA damaging drugs, radiation, or
  oxidative stress), the cell initiates a Suicide Program that results in death by APOPTOSIS.

Two phenomena consistently characterize IRREVERSIBILITY:
1. The Inability to reverse Mitochondrial Dysfunction (lack of oxidative phosphorylation and ATP generation) even after resolution of the original injury

2. Profound DISTURBANCES in Membrane Function.

*** Leakage of intracellular proteins through the damaged cell membrane and ultimately into the circulation provides a means of detecting tissue-specific cellular injury and necrosis using BLOOD SERUM SAMPLES!!!!!!*****

• The release of cfDNA into the bloodstream occurs by different sources, including the Primary Tumor, Tumor Cells that circulate in peripheral blood, Metastatic deposits present at distant sites, and Normal cell types, such as hematopoietic and stromal cells.
• Thus, both Tumor and Normal cfDNA circulate in the bloodstream of patients with cancer.
• Its rapidly Increased accumulation in blood during tumor development is caused mainly by an Excessive DNA Release by APOPTOTIC AND NECROTIC cells.
• In addition, active secretion within exosomes has been demonstrated, but it is still discussed whether this is a relevant or rather minor source of cfDNA.

Question 20

Clinical Correlations

Selected Examples of Cell Injury and NECROSIS:

Answer 20

1) ISCHEMIC AND HYPOXIC INJURY:
- Ischemia is the MOST COMMON TYPE OF CELL INJURY IN CLINICAL MEDICINE and it results from hypoxia induced by reduced blood flow, most commonly due to a mechanical arterial obstruction.

2) INSCHEMIA- REPERCUSSION INJURY:
- Restoration of blood flow to ischemic tissues can promote recovery of cells if they are reversibly injured, but can also paradoxically exacerbate the injury and cause cell death.

3) CHEMICAL (TOXIC) INJURY:
- Chemical injury REMAINS FREQUENT PROBLEM IN CLINICAL MEDICINE AND IS A MAJOR LIMITATION TO DRUG THERAPY!!!!

Question 21

Myocardial Infarction

Answer 21

• The American College of Cardiology/American Heart Association (ACC/AHA) guidelines on Unstable Angina/NSTEMI recommend that in patients with suspected myocardial infarction, CARDIAC BIOMARKERS should be MEASURED AT PRESENTATION.
• The guidelines recommend a total turnaround time of less than 1 hour and preferably LESS THAN 30 minutes for the Cardiac Biomarker Measurements
• TROPONIN is plentiful in Heart Muscle. It should also make sense that Troponin is NOT FOUND FREELY in Blood. However when Cardiac Muscle dies, Troponin are released into the Blood. This can be used to the Advantage of the Caregiver in determine the cause of Potential Symptoms. Thus, point of Care tests have been developed for Basic Health Care Services and Emergency rooms for the detection of Cardiac Muscle Death. These tests will be perform several times between 6 to 12 hours AFTER Symptoms of Heart Attack present!!!!!

Question 22

Progression of Myocardial Infarction

Answer 22

TIME:

a) Seconds:
- ONSET of ATP Depletion

b) Less than 2 Min:
- Loss of CONTRACTILITY

c) 10 Min:
- ATP Reduced to 50% of Normal

d) 40 Min:
- ATP Reduced to 10% of Normal

e) Greater than 1 Hour:
- MICROVASCUALR INJURY!!!

* 20 to 40 min is IRREVERSIBLE CELL INJURY!!!!!!!!!!!!!**

Question 23

Pattern of Necrosis in Myocardial Infarction

Answer 23

• Microscopic features of Myocardial Infarction and tis repair.
  1) A ONE DAY OLD Infarction showing COAGULATIVE NECROSIS AND WAVY FIBERS (Elongated and Narrow, as compared with Adjacent normal Fibers)
• WIDENED SPACES between the DEAD FIEBRS contain EDEMA FLUID and SCATTERED NEUTROPHILS.
  2) 3 to 4 Days Old: Dense Polymorphonuclear LEUKOCYTIC INFILTRATE in an Acute Myocardial Infarction
  3) 7 to 10 Days Old: REMOVAL of Necrotic Myocytes by PHAGOCYTOSIS
  4) Granulation tissue characterized by LOOSE COLLAGEN and ABUNDANT CAPILLARIES
  5) Healed Myocardial Infarction: The Necrotic Tissue has been replaced by a DENSE COLLAGENOUS SCAR. The Residual Cardiac Muscle cells show evidence of COMPENSATORY HYPERTROPHY!!!!!!

Question 24

Apoptosis

Answer 24

• Apoptosis is a pathway of Cell Death that is induced by a tightly regulated SUICIDE PROGRAM in which cells destined to die ACTIVATE INTRINSIC ENZYMES that DEGRADE the cells’ own nuclear DNA and Nuclear and Cytoplasmic Proteins.

CAUSES:

1) PHYSIOLOGIC SITUATIONS:
- Death by apoptosis is a normal phenomenon that serves to ELIMINATE Cells that are no longer needed, and to maintain a steady number of various cell populations in tissues.

2) PATHOLOGIC SITUATIONS:
a) DNA Damage (S Phase)
b) Accumulation of MISFOLDED Proteins
c) Cell Death in CERTAIN Infection
d) Pathological ATROPHY in Parenchymal Organs AFTER Duct Obstruction

Question 25

Mechanisms of Apoptosis

Answer 25

• Apoptosis results form the ACTIVATION of Enzymes called CASPASES (Cysteine PROTEASES that cleave Proteins AFTER Aspartic Residues)

Question 26

Extrinsic Pathway

Answer 26

• This pathway is initiated by engagement of plasma membrane death receptors on a variety of cells.
  1) The ligand for Fas is called Fas LIGAND(FasL). FasL is expressed on T CELLS that RECOGNIZE SELF ANTIGENS (and functions to ELIMINATE Self-Reactive Lymphocytes), and on SOME CYTOTOXIC T LYMPHOCYTES (which kill virus-infected and tumor cells).

Question 27

Clfinicopathologic Correlation: Apoptosis in Health and Disease

ENABLERS of GENOMIC Stability

Answer 27

Gene:
- TP53

PROTEIN:

• p53 Protein
• ARRESTS CELL AT G1**

FUCNTION:
- Cell Cycle ARREST and APOPTOSIS in Response to DNA Damage

FAMILIAL SYNDROMES:
- Li-Fraumeni Syndrome (Diverse Cancers)

SPORADIC CANCERS:
- Most Human Cancers

Question 28

Diseases from Apoptosis

Answer 28

1) Alzheimer
2) Huntington
3) Parkinson
4) Type 2 DM

Question 29

Features of Necrosis and Apoptosis

Answer 29

NECROSIS:

1) Cell Size:
- ENLARGED (Swelling)

2) Nucleus:
- Pyknosis —-> Karyorrhexis ———> Karyolysis

3) Plasma Membrane:
- DISRUPTED

4) Cellular Contents:
- Enzymatic Digestion; May leak out of Cell

5) Adjacent Inflammation:
- FREQUENT

6) Physiologic or Pathologic Role:
- Invariably PATHOLOGIC (Culmination of IRREVERSIBLE Injury)

APOPTOSIS:

1) Cell Size:
- REDUCED (Shrinkage)

2) Nucleus:
- Fragmentation into NUCLEOSOME- Size Fragments

3) Plasma Membrane:
- INTACT; Altered Structure, especially Orientation of Lipids

4) Cellular Contents:
- INTACT’ May be released in Apoptotic Bodies

5) Adjacent Inflammation:
- NO

6) Physiologic or Pathologic Role:
- Often Physiologic, means of ELIMINATING Unwanted Cells; May be Cell Pathologic after some forms of Cell Injury, ESPECIALLY DNA DAMAGE!!!!!!!!!!!!!!

Question 30

Manifestations of Metabolic Derangements

Answer 30

• One of the MANIFESTATIONS OF METABOLIC DERANGEMENTS in cells is the intracellular accumulation of abnormal amounts of various substances that may be harmless or associated with varying degrees of injury. The substance may be located in the cytoplasm, within organelles (typically lysosomes), or in the nucleus, and it may be synthesized by the affected cells or may be produced elsewhere.

1) ABNORMLA METABOLISM:
- In developed nations, the most common causes of significant fatty change in the liver (FATTY LIVER) are ALCOHOL ABUSE and NONALCOHOLIC Fatty Liver disease, which is often associated with DIABETES and OBESITY.

2) DEFECT IN PROTEIN FOLDING:
- Intracellular ACCUMULATIONS of Proteins usually appear as Rounded, Eosinophilic Droplets, Vacuoles, or Aggregates in the CYTOPLASM.

Ex:
a) Misfiled Protiens in Alpha 1- Antitrypsin Deficiency

b) RUSSEL BODIES are Plasma Cells constipated with Immunoglobulin Proteins

3) LACK OF ENZYME:
- FAILURE to DEGRADE a Metabolite due to inherited Enzyme DEFICIENCIES. The resulting disorders are called storage diseases (Table 5-6, Chapter 5).

4) Ingestion of Indigestible Materials:
a) EXOGENOUS: Anthracosis or Tattoo

b) ENDOGENOUS: Lipofuscin, Melanin, Hemosiderin

Question 31

Pathologic Calcification

Answer 31

A) DYSTROPHIC: May simply be a Telltale sing of previous Cell Injury resulting in NECROSIS, it is often a cause of Organ Dysfunction

B) METASTATIC (A Change in Position, State, or Form) ca can be due to Hypercalcemia:

1) Hyperparathyroidism
2) Resorption of Bone
3) Vitamin D Related Disorders
4) Renal Failure

Question 32

Age

Answer 32

• Aging has important health consequences, because AGE is one of the STRONGEST INDEPENDENT RISK FACTORS for many CHRONIC DISEASES, such as CANCER, ALZHEIMER DISEASE, and ISCHEMIC HEART DISEASE
• Cellular aging is the result of a Progressive DECLINE in Cellular Function and viability caused by Genetic Abnormalities and the accumulation of cellular and molecular damage due to the effects of EXPOSURE to Exogenous Influences.

Question 33

Things that cause Cellular Aging

Answer 33

1) Carcinogen Exposure, Sporadic Errors:
- ROS which lead to DNA DAMAGE!!!!!
* ** Mutations***

2) Cellular Senescence:
- Telomere Shortening which leads to a DECREASE in CELLULAR REPLICATION!!!!
* * Cell Loss*

3) Defection Protein Homeostasis:
- Can lead to DECREASED Proteins, Damaged Proteins
* ** Decreased Cell Functions***