MDS PREP
Indirect chemical carcinogens differ from direct acting agents in those
indirect agents:
1. Induce carcinogenicity without chemical transformation
2. Induce carcinogenicity after chemical transformation
3. Don’t require metabolic conversion
4. None of the above
Pathology Answer: 2
Indirect chemical carcinogens differ from direct acting agents in that they
require metabolic activation to exert their carcinogenic effects. This means
that indirect carcinogens must undergo a chemical transformation within the body
before they can damage DNA and induce cancer. Direct acting carcinogens, on the
other hand, can interact directly with DNA without the need for metabolic
conversion. Therefore, the correct answer is:
2. Induce carcinogenicity after chemical transformation
1. Induce carcinogenicity without chemical transformation: This statement is
incorrect for indirect chemical carcinogens. Indirect carcinogens are typically
non-reactive or less reactive in their original form and must undergo metabolic
activation to become DNA-reactive. This metabolic conversion is crucial for
their carcinogenic potential.
2. Induce carcinogenicity after chemical transformation: This is the correct
explanation. Indirect carcinogens require metabolic activation by the body's
enzyme systems, particularly phase I enzymes such as cytochrome P450, to convert
them into electrophilic or reactive intermediates that can interact with DNA.
This activation process can occur in various tissues, often the liver, where
these enzymes are present. The reactive metabolites then form DNA adducts, which
can lead to mutations and ultimately cancer if not repaired properly by the
cell's DNA repair mechanisms.
3. Don’t require metabolic conversion: This statement is incorrect. Indirect
carcinogens do require metabolic conversion to become active carcinogens. It is
the direct acting carcinogens that can interact with DNA without the need for
such activation because they are already electrophilic or reactive in their
original form.
Letterer-Siwe disease is a disturbance of
1) Protein metabolism
2) Lipid metabolism
3) Mucopolysaccharide metabolism
4) Carbohydrate metabolism
Oral Pathology
Answer: 2
Letterer-Siwe disease is a type of Langerhans cell histiocytosis that is associated with disturbances in lipid metabolism.
Letterer-Siwe disease is a form of Langerhans cell
histiocytosis (LCH), which is characterized by the proliferation of
Langerhans cells, a type of dendritic cell involved in immune response. This
disease primarily affects children and can present with a variety of symptoms,
including:
Bone Lesions: Osteolytic bone lesions, particularly in
the skull, vertebrae, and long bones.
Skin Rash: Erythematous lesions or seborrheic
dermatitis-like rashes.
Hematological Abnormalities: Anemia, thrombocytopenia,
and leukopenia may occur.
Organ Involvement: It can affect multiple organs,
including the liver, spleen, and lungs.
Metabolic Disturbance:
Lipid Metabolism: Letterer-Siwe disease is associated
with disturbances in lipid metabolism, particularly due to the accumulation
of lipids in the affected tissues. The Langerhans cells in this condition
can exhibit abnormal lipid storage, which is a hallmark of the disease.
Which of the following may be a feature of acromegaly?
1. Large tongue
2. Micrognathia
3. Hypoglycaemia
4. Crowded teeth
Oral Pathology
Answer: 1
A large tongue is a common feature of acromegaly.
The major stimulator of monocytes
1. IL-I
2. ã-interferon
3. IgE
4. lgG
Pathology Answer: 1
1. Interleukin-1 (IL-1): Interleukin-1 is a pro-inflammatory cytokine that
plays a crucial role in the activation and regulation of the immune system. It
is produced mainly by macrophages and monocytes in response to various stimuli,
including bacterial endotoxins, viruses, and tissue damage. IL-1 is a major
stimulator of monocytes, as it promotes their proliferation, differentiation
into macrophages, and enhances their phagocytic and antigen-presenting
capabilities. It also induces the production of other cytokines, such as
TNF-alpha and IL-6, which further amplify the inflammatory response. Thus, it
acts as a critical mediator in the early stages of the immune response and is
involved in the initiation of the acute phase reaction.
2. α-Interferon: Interferons (IFNs) are a family of cytokines that play an
essential role in the innate immune response to viral infections. They are
mainly produced by cells in response to viral infection and can induce an
antiviral state in nearby cells by upregulating the expression of proteins that
inhibit viral replication. While α-interferon does not directly stimulate
monocytes, it does have some effects on the immune system, such as enhancing the
natural killer (NK) cell activity and modulating the function of macrophages and
other immune cells. However, it is not the primary stimulator of monocytes like
IL-1 is.
3. Immunoglobulin E (IgE): IgE is a class of antibodies that are involved in the
allergic response and the immune response to parasites. It is produced in
response to allergens and parasitic antigens. While IgE is important in the
activation of mast cells and basophils, which play a key role in the immediate
allergic response, it does not serve as a major stimulator of monocytes.
Monocytes are more closely associated with the innate immune response and are
not primarily activated by antibodies.
4. Immunoglobulin G (IgG): IgG is the most abundant and versatile class of
antibodies in the blood. It plays a pivotal role in the immune response by
binding to pathogens and facilitating their destruction through various
mechanisms, such as opsonization (enhancing phagocytosis), activation of the
complement system, and neutralization of toxins. IgG can interact with
macrophages via Fcγ receptors, which can lead to phagocytosis of
antigen-antibody complexes. However, IgG is not a direct stimulator of monocytes
in the same sense that IL-1 is. Monocytes are primarily activated by cytokines
and other signaling molecules released during inflammation and infection, rather
than by antibodies.
Mitotic delay is longer with
1. Smaller dose
2. Moderate dose
3. Large dose
4. A and B
Oral Pathology
Answer: 3
Mitotic delay is longer with a large dose of radiation.
A patient who has geen given tumoricidal dose of radiotherapy recently reports to dental clinic with painful carious exposed mandibular first molar with periapical abscess. The treatment of choice should be
1. Extraction of the offending tooth
2. Root canal treatment if possible
3. No treatment should be given
4. Incision and drainage of abscess
Oral Pathology
Answer: 2
Root canal treatment is the treatment of choice for a patient with a painful carious exposed mandibular first molar with periapical abscess.
What of the following is characterized by left lower quadrant periumbilical pain in an elderly person, with the presence of fever, tender abdomen, leukocytosis, nausea, and vomiting?
1) Acute appendicitis
2) Diverticulitis
3) Gallstones
4) Pancreatitis
General Pathology Answer: 2
Diverticulitis is characterized by left lower quadrant pain, fever, and leukocytosis, especially in elderly patients.
For extraction in a leukaemic patient
1. Consult physician
2. Obtain WBC count
3. Ontain platelet count
4. All of the above
Oral Pathology
Answer: 4
For extraction in a leukemic patient, all of the above steps should be taken.