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Quellung phenomenon 606 quinidine (β-quinine; 6′-methoxycinchonan-9-ol)
Quartenary structure.
quaternary syphilis is seen more often in AIDS patients
also infected with Treponema pallidum who show increased
susceptibility to neurosyphilis.
Quellung phenomenon
Swelling of the pneumococcus capsule fol lowing exposure to
antibodies against pneu mococci. Refer to Quellung reaction.
Quellung reaction
Swelling of bacterial capsules when the microorganisms
are incubated with species-specific antiserum.
Examples of bacteria in which this can be observed include
Streptococcus pneumoniae, Hemophilus influenzae,
Neisseria, and Klebsiella species. The combination of a
drop of antiserum with a drop of material from a patient
containing an encapsulated microorganism and the addition
of a small loopful of 0.3% methylene blue produces the
Quellung reaction. The microorganisms are stained blue
and are encircled by a clear halo that resembles swelling,
but is in fact antigen–antibody complex produced at the
CH 3 O
COO –
N
N
COO –
COO –
Quin-2.
CH 3
surface of the organism. The reaction is due to an alteration
of the refractory index.
quenching
When immunofluorescent cell or tissue preparations treated
with fluorochrome-labeled antibodies are exposed to ultraviolet
light under a microscope, the emission of fluorescent
radiation from the fluorochrome label diminishes as a result
of quenching. The term may also refer to diminished efficiency
of assaying radioactivity in a scintillation counter by
such agents as ethanol or hydrogen peroxide (H 2O 2).
Quin-2
A derivative of quinoline that combines with free Ca 2+ to
accentuate fluorescence intensity. It can be introduced into
cells as an ester followed by de-esterification. When T or B
lymphocytes containing Quin-2 are activated, their fluorescence
intensity rises, implying an elevation of free Ca 2+ in
the cytosol.
quinidine (-quinine; 6′-methoxycinchonan-9-ol)
A stereoisomer of quinine recognized for its cardiac antiarrhythmic
effects.
N
O
COO –