Term
| State the differences between G+ and G- bacteria. |
|
Definition
G+: cell wall thicker
G-: LPS outer membrane = additional barrier to drug penetration |
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Term
State whether the following combinations of antibiotics give a synergistic, additive, or inhibitory effect:
- bactericidal + bactericidal
- bacteriostatic + bacteriostatic
- bactericidal + bacteriostatic |
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Definition
- synergystic and additive
- additive
- inhibitory to each other |
|
|
Term
Describe the following methods of acquisition of resistance.
- conjugation
- transduction
- transformation |
|
Definition
- conjugation: transfer via physical contact b/t 2 organisms
- transduction: transfer via bacteriophage
- transformation: acquisition from the environment |
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Term
| List 3 common mechanisms by which MRSA shows resistance. |
|
Definition
1. beta-lactamase digestion of beta-lactams
2. REMODELED peptidoglycan to which Vancomycin no longer binds
3. THICKENED peptidoglycan |
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Term
| How does low O2 tension change the effect of antimicrobials? |
|
Definition
| low O2 tension---> impairs phagocytic activity of WBCs; slows microbial replication---> causing bacteriocidal drugs to be less effective |
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|
Term
| How soon should an antimicrobial generate a noticeable therapeutic effect? |
|
Definition
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|
Term
| Are antibiotics that inhibit cell wall synthesis bacteriostatic or bactericidal? |
|
Definition
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Term
| Why is the penicillin, Piperacillin, administered in combination with Tazobactam? |
|
Definition
| Tazobactam = penicillinase inhibitor |
|
|
Term
| What is the purpose of Clavulilanic acid and Tazobactam? |
|
Definition
| beta-lactamase inhibition |
|
|
Term
To which cell wall synthesis inhibitor group do the following new drugs belong to?
- carbapenems
- monobactams |
|
Definition
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|
Term
| How will antacids affect ketoconazole absorption? |
|
Definition
| raises pH---> poorer absorption from GI tract |
|
|
Term
| Which azole antifungal distributes to the CNS? |
|
Definition
|
|
Term
| Which azole antifungal decreases steroid biosynthesis? |
|
Definition
|
|
Term
| How is the mechanism of azole antifungals different from that of the antifungal - Terbinafine? |
|
Definition
| Terbinadine inhibits the step prior to that inhibited by azole antifungals in the biosynthesis pathway of ergosterol. |
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|
Term
| Which nucleic acid-affecting antibiotic is contraindicated in pregnancy for being a teratogen? |
|
Definition
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|
Term
To which class of protein synthesis inhibitors do the following drugs belong to?
- Gentamicin
- Amikacin
- Tobramycin
- Netilmicin |
|
Definition
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|
Term
Differentiate between bone marrow toxicity and aplastic anemia (caused by Chloramphenicol) in the following categories:
- appearance of marrow
- peripheral blood
- dose-response
- time of appearance
- common symptoms
- prognosis |
|
Definition
marrow: TOXIC: normocellular; APLASTIC: hypoplastic/aplastic
peripheral bld: TOXIC: anemia; APLASTIC: pancytopenia
dose-response: TOXIC: dose related; APLASTIC: not dose related
time of appearance: TOXIC: during treatment; APLASTIC: days/months later
common symptoms: TOXIC: anemia; APLASTIC: purpura and/or hemorrhage
prognosis: TOXIC: recovery; APLASTIC: often fatal |
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|
Term
| Which two protein synthesis inhibitors can be used in the case of Vancomycin resistance? |
|
Definition
| Quinupristin/Dalfopristin |
|
|
Term
| Explain the general mechanism of action by antimetabolite antibiotics. |
|
Definition
| drug--->occupied active site of enzyme---> unavailable to catalyze reaction |
|
|
Term
| How are more recent sulfonamides better than the previous types? |
|
Definition
| more soluble in acidic urine pH---> better excretion |
|
|
Term
| Describe the purpose of sequential inhibition. |
|
Definition
| antimetabolite prevents build-up of metabolite that would otherwise compete off an antimetabolite that blocks the next sequential step of the given biosynthesis pathway |
|
|
Term
| Describe sequential inhibition of folic acid synthesis. |
|
Definition
PABA---> Folate (blocked by Sulfonamides)
Folate---> Tetrahydrofolate (blocked by Trimethoprim) |
|
|
Term
| Which class of genes act as the "gas pedal" and "breaks" of carcinogenesis? |
|
Definition
gas: oncogenes (normal homologs---> protooncogenes)
breaks: tumor suppressor genes |
|
|
Term
| Define the term "high growth fraction." |
|
Definition
| high fraction of cells are going through cell cycle |
|
|
Term
| Distinguish between cycle active and non-cycle active. |
|
Definition
cycle active: more useful in population with high growth fraction
non-cycle active: able to kill at any stage of cycle |
|
|
Term
| Explain the "cell kill hypothesis." |
|
Definition
| 100% of the tumor cells MUST be killed, to prevent the return of cancer from remaining cancer cells. |
|
|
Term
| What is the relationship between a solid tumor growth and growth fraction? |
|
Definition
| tumor size is INVERSELY PROPORTIONAL to growth fraction (because cells are running out of resources) |
|
|
Term
| Which two components are vital for effective chemotherapy? |
|
Definition
selectivity
ability of normal cell populations to regenerate |
|
|
Term
| What are the two most serious adverse events of chemotherapy? |
|
Definition
infection (from bone marrow activity supression)
hemorrhage |
|
|
Term
| Why are tyrosine kinase inhibitors useful in cancer chemo? |
|
Definition
| TK's---> phosphorylate cellular components---> activate gene transcription needed for cell proliferation |
|
|
Term
| How are antibodies (e.g. Trastuzumab) used as chemotherapy? |
|
Definition
| to inhibit action of oncogene (e.g. HER2 receptor blocking---> delivered via IgG in combination with Pertuzumab (prevents dimerization of HER2) |
|
|
Term
| Describe the affect of histone acetylation on gene txn. |
|
Definition
| acetylation---> open configuration---> txn |
|
|
Term
| Describe the affect of DNA methylation on gene txn. |
|
Definition
| methylation---> down-regulation of genes---> gene suppression |
|
|
Term
| Describe the relationship between MGMT gene silencing and Temozolomide treatment. |
|
Definition
| methylated MGMT---> unable to repair alkyation damaged DNA---> allows Temozolomide (alkylating agent) to inhibit growth of glioblastoma |
|
|
Term
| What is the significance of sarcosine in pts with prostate cancer? |
|
Definition
| = measure of liklihood of invasion and metastasis |
|
|
Term
Distinguish between immunological, interferon, and chemical approaches to the control of viral infections in the following areas:
- level of effectiveness
- spectrum
- duration |
|
Definition
effectiveness: IMMUNO: high; INTERF: moderate/high; CHEM: low
spectrum: IMMUO and CHEM: narrow; INTERF: broad
duration: IMMUNO: long; INTERF and CHEM: short |
|
|
Term
| What option does an amantadine-resistant pt have to treat and prevent an influenza A infection? |
|
Definition
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|
Term
| Distinguish between the 3 types of interferons produced in response to viral infections. |
|
Definition
alpha - used most
beta - produced by most cells
gamma - less direct antiviral activity, stimulates T-cells) |
|
|
Term
| Describe the mechanism of attachment of HIV to a T-cell. |
|
Definition
| HIV-gp120 binds T-cell-CD4---> coreceptor (CCR5 or CXCR4) solidifies binding |
|
|
Term
| What is the biggest challenge to antiretroviral therapy? |
|
Definition
| reverse transcriptase---> ERROR PRONE---> high rate of mutation confers resistance |
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