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NON mouse 534 nonproductive rearrangement
NON mouse
The normal control mouse for use in studies involving
the NOD mouse strain that spontaneously develops type I
(insulin-dependent) diabetes mellitus. The two strains differ
only in genes associated with the development of diabetes.
Nonobese normal mouse.
non-A non-B hepatitis
Refer to hepatitis, non-A and non-B.
non-classical Hodgkin lymphoma
Nodular lymphocyte-predominant Hodgkin lymphoma that
comprises 5% of all Hodgkin lymphomas. The neoplastic
cells are CD30-, CD15-, CD19 + , and CD20 + popcorn cells.
non-Hodgkin lymphoma (NHL)
All lymphoid neoplasms without the characteristics of
Hodgkin disease constitute non-Hodgkin lymphomas.
They are monoclonal lymphoid neoplasms that are very
heterogeneous morphologically, antigenically, and with
respect to kinetic phenotypes. They also differ greatly in
clinical expression. They are divided into low, intermediate,
and high grade. Low grade lymphomas are treated
conservatively. Intermediate and high grade lymphomas
are aggressive and are appropriately treated. T lymphocyte,
B lymphocyte, and NULL cell lymphomas make
up the NHL group. Tumor derived from a transformed
peripheral B cell or occasionally a transformed peripheral
T cell. A heterogeneous group of neoplasms that include
precursor B lymphoblastic leukemia/lymphoma, mantle
cell lymphoma, B cell chronic lymphocytic leukemia,
follicular lymphoma, mucosa-associated lymphoid tissue
lymphoma, diffuse large cell lymphoma, Burkitt’s lymphoma,
precursor T lymphoblastic leukemia/lymphoma,
adult T cell leukemia/lymphoma, mycosis fungoides,
Sezary syndrome, anaplastic large cell lymphomas, angioimmunoblastic
T cell lymphoma, and peripheral T cell
lymphoma (unspecified.)
nonadherent cell
A cell that fails to stick to a surface such as a culture flask.
A lymphocyte is an example. Conversely, macrophages
readily adhere to the glass surfaces of tissue culture flasks.
noncovalent forces
Include hydrogen bonding, ionic or Coulombic bonding,
Van der Waals interactions, hydrophobic bonding, and steric
repulsion forces that are extremely sensitive to distances
between interacting groups. Although charged on antigen–
antibody binding, these forces may play a very important
role in determining the stability of the antigen–antibody
complex. The literature differs on the issue of whether
charged antigens elicit antibodies of reciprocal charge effect
per se or if the effect is exerted by the microenvironment of
the antigen and antibody molecules and not so much by the
net of the molecules as a whole.
noncytopathic virus
A virus that appropriates cellular functions and reproduction
without injuring the host cell.
nondeletional tolerance
The development of donor-specific tolerance without
a discernible change in anti-donor reactivity in vitro.
Nondeletional tolerance develops to antigen-presenting cell
(APC)-depleted islet or thyroid allografts.
nonhomologous end-joining (NEHJ) pathway
A DNA repair pathway possessed by all cells that repairs
double-stranded DNA breaks without the requirement for
DNA sequence homology between the ends to be joined. The
DNA ends are merely ligated back together. Some of the proteins
that participate in V(D)J recombination are involved.
nonimmunologic classic pathway activators
Selected microorganisms such as Escherichia coli and
low-virulence Salmonella strains and certain viruses such
as parainfluenza react with C1q and lead to C1 activation
without antibody which represents classic pathway activation
that facilitates defense mechanisms. Various other
substances such as myelin basic protein, denatured bacterial
endotoxin, heparin, and urate crystal surfaces may also
directly activate the classic complement pathway.
nonmyeloablative conditioning
A diminished level of chemotherapy that induces only partial
depletion of the bone marrow as part of the conditioning
process prior to transplantation.
nonobese normal mice (NON mice)
Normal control mice for use in studies involving the
nonobese diabetic (NOD) mouse strain that spontaneously
develops type I (insulin-dependent) diabetes mellitus. The
two strains differ only in genes associated with the development
of diabetes.
nonprecipitating antibodies
The addition of antigen in increments to an optimal amount
of antibody precipitates only ~78% of the amount of antibody
that would be precipitated by one-step addition to the
antigen. This demonstrates the presence of both precipitating
and nonprecipitating antibodies. Although the nonprecipitating
variety cannot produce formation of insoluble
antigen–antibody complexes, they can be assimilated into
precipitates that correspond to their specificity. Rather than
being univalent as was once believed, they may merely
have a relatively low affinity for the homologous antigen.
Monogamous bivalency, which describes the combination
of high affinity antibody with two antigenic determinants
on the same antigen particle, represents an alternative
explanation for the failure of these molecules to precipitate
with their homologous antigen. The formation of nonprecipitating
antibodies, which usually represents 10 to 15% of
the antibody population produced, is dependent upon such
variables as heterogeneity of the antigen, characteristics
of the antibody, and animal species. The equivalence zone
is narrower with native proteins of 40 to 60 kDa and their
homologous antibodies than with polysaccharide antigens
or aggregated denatured proteins and their specific antibodies.
The equivalence zone with synthetic polypeptide
antigens varies with the individual compound used. The
solubility of antibody–antigen complexes and the nature
of the antigen are related to these variations at the equivalence
zone. The extent of precipitation is dependent upon
characteristics of both the antigen and antibody. At the
equivalence zone, not all antigen and antibody molecules
are present in the complexes. For example, rabbit anti-BSA
(bovine serum albumin) precipitates only 46% of BSA at
equivalence.
nonproductive rearrangement
Rearrangements in which gene segments are joined out
of phase, leading to failure to preserve the triplet-reading
frame for translation. Nonproductive rearrangements of
gene segments encoding T and B cell receptors lead to failure
to encode a protein because the coding sequences are in
the wrong translational reading frame.