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Sabin–Feldman dye test 634 SAMS
local immunity in the intestine. His vaccine largely
replaced the earlier Salk vaccine.
Sabin–Feldman dye test
An in vitro diagnostic test for toxoplasmosis. Serial dilutions
of serum are combined with Toxoplasma gondii
microorganisms and complement is added. If specific
antibodies against Toxoplasma organisms are present
in the serum, complement interrupts the integrity of the
toxoplasma membrane, admitting methylene blue that is
added to the system and stains the interior of the organism.
The dilution of serum in which one half of the Toxoplasma
organisms are killed is the titer.
Sabin vaccine
An attenuated live poliomyelitis virus vaccine administered
orally to induce local immunity in the gut, which is the natural
route of entry of the virus, thereby stimulating local and
systemic immunity against the causative agent of the disease.
saccharated iron oxide
Colloidal iron oxide employed to investigate the phagocytic
capacity of mononuclear phagocytes.
sacculus rotundus
The lymphoid tissue-rich terminal segments of the ileum
of the rabbit; a component of the gut-associated lymphoid
tissue (GALT).
sago spleen
The replacement of lymphoid follicles by circular and transparent
amyloid deposits in amyloidosis of the spleen.
SAIDS (simian acquired immune deficiency syndrome)
An immunodeficiency of rhesus monkeys induced by retrovirus
group D. The animals develop opportunistic infections
and tumors. Their CD4 lymphocytes decrease, and
they suffer wasting and develop granulomatous encephalitis.
The sequence homology between simian immunodeficiency
virus (SIV) and human immunodeficiency virus 1
(HIV-1) is minimal, but the sequence homology between
SIV and HIV-2 is significant.
saline agglutinin
An antibody that causes the aggregation or agglutination of
red blood cells, bacterial cells, or other particles in 0.15 M
salt solutions without additives.
Jonas Salk.
Salk, Jonas (1914–1994)
American physician working at the University of Pittsburgh
who prepared the first effective polio vaccine including
all three types of viruses inactivated by formaldehyde. It
proved safe and effective and was used in 650,000 children
in 1954.
Salk vaccine
An injectable, inactivated poliomyelitis vaccine containing
virus killed by formalin. It was used for prophylactic immunization
against poliomyelitis prior to development of the
Sabin oral vaccine.
Salmonella immunity
Natural immunity and adaptive immunity are necessary for
survival following primary infection with virulent microorganisms
of this genus. Salmonellae grow exponentially
in the reticuloendothelial system and may reach 10 8 microorganisms—a
lethal number, apparently due to endotoxin
activity. The balance between strain virulence and host
resistance controls the rate at which bacterial cells increase
in the reticuloendothelial system. Bone marrow-derived cells,
tumor necrosis factor α (TNF-α), interferon-γ (IFN-γ), and
interleukin-12 (IL12), but not T lymphocytes, control early
growth (plateau phase), after which an immune response
phase clears the microorganisms from tissues and provides
effective immunity to reinfection. CD4 + and CD8 + T lymphocytes
along with TNF-α, IFN-γ, and IL12 help clear bacteria
from the tissues, but antibody is also required in addition
to cell-mediated immunity. The antibody may be directed
against lipopolysaccharide (LPS) in animal infections; antibodies
to Vi antigen are believed to be significant in humans.
The diagnosis of typhoid fever is based on the detection of
antibodies to O and H antigens and to Vi antigens in carriers.
Immunization with killed Salmonellae does not induce cellmediated
immunity and confers less protection than immunization
with live organisms that induce both cell-mediated
and humoral immunity. Antibody alone is not protective. The
protective immunogen is probably LPS O or Vi in S. typhi,
other protein antigens, or a combination. IgA provides partial
immunity. Because killed microorganisms used in vaccines
in the past did not induce appropriate cell-mediated immunity
and were highly reactogenic, live vaccines of superior
efficacy in experimental models are under development.
SALT
Abbreviation for skin-associated lymphoid tissue.
salting out
Salt precipitation of serum proteins such as globulins.
salt precipitation
An earlier method to separate serum proteins based on the
principle that globulins precipitate when the concentration
of sodium sulfate or ammonium sulfate is less than the
concentration at which albumin precipitates. Euglobulins
precipitate at concentrations below those at which pseudoglobulins
precipitate. Salt precipitation was largely replaced
by chromatographic methods using Sephadex ® beads and
related techniques.
salvage pathway of nucleic acid synthesis
Construction of nucleotides from degraded spent nucleic
acids through the actions of adenosine deaminase and
purine nucleoside phosphorylase (PIMP).
salvage therapy
An extraordinary effort to rescue a patient with refractory
cancer through an innovative or experimental
treatment.
Salvarsan (606)
Arsenical compound developed by Paul Ehrlich for the
treatment of syphilis.
SAMS
Abbreviation for substrate adhesion molecules.