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gastrin-producing cell antibodies (GPCAs) 289 gemtuzumab
of this condition, and poor responsiveness to H2-receptor
antagonists; however, other investigators have failed to
confirm these results.
gastrin-producing cell antibodies (GPCAs)
Antibodies present in 8 to 16% of antral (type B) chronic
atrophic gastritis patients. GPCAs may lead to diminished
gastrin secretion and fewer gastrin-producing cells in antral
gastritis. There are no parietal cell antibodies present, and
GPCAs are not linked to pernicious anemia. GPCAs in type
B gastritis are different from gastric fundus parietal cell
antibodies that have been linked to fundal mucosal atrophy
in type A gastritis.
gastrin-producing cell autoantibodies (GPCAs)
Autoantibodies found in 8 to 16% of patients with antral
(type B) chronic atrophic gastritis, which primarily affects
the antral mucosa. Parietal cell autoantibodies (PCA) are
not present, and the autoantibodies are not associated with
pernicious anemia or polyendocrinopathy. The GPCAs are
believed to be responsible for the diminished gastrin secretion
and fewer gastrin-producing cells in antral gastritis.
PCAs are found only in patients with normal antral mucosa.
By contrast, GPCAs are present only in patients with normal
antral mucosa or mild antral gastritis but not in individuals
with moderate or severe antral gastritis. Helicobacter
pylori has a world-established association with antral (type
B) gastritis and peptic ulcer disease, but antibodies against
H. pylori are not helpful for monitoring the disease.
gastrin receptor antibodies
These antibodies are claimed to be present in 30% of pernicious
anemia patients by some investigators, but this finding
has not been confirmed. Gastric receptor antibodies may
inhibit gastrin binding and have been demonstrated to bind
gastric parietal cells.
GATA-2 gene
A gene that encodes a transcription factor required for
the development of lymphoid, erythroid, and myeloid
hematopoietic cell lineages.
gatekeeper effect
Contraction of endothelium mediated by immunoglobulin
E (IgE), permitting components of the blood to gain access
to the extravascular space as a consequence of increased
vascular permeability.
gay bowel syndrome
A constellation of gastrointestinal symptoms in homosexual
males related to both infectious and noninfectious etiologies
before the acquired immune deficiency syndrome (AIDS)
epidemic. Clinical features include alterations in bowel
habits, condyloma acuminata, bloating, flatulence, diarrhea,
nausea, vomiting, adenomatous polyps, fistulas, fissures,
hemorrhoids, and perirectal abscesses, among many other
features. Associated sexually transmitted infections include
syphilis, herpes simplex, gonorrhea, and Chlamydia
trachomatis. Numerous other microbial species identified
include human papilloma virus, Campylobacter organisms,
hepatitis A and B, cytomegalovirus, and parasites such as
Entamoeba histolytica. Treatment varies with the etiology
of gay bowel syndrome manifestations.
GCDFP-15 (23A3)
Gross cystic disease fluid protein-15 is a 15,000-Da glycoprotein
localized in the apocrine metaplastic epithelium
lining breast cysts and in apocrine glands in the axilla,
vulva, eyelid and ear canal. Approximately 70% of breast
carcinomas stain positive with antibody to GCDFP-15.
Colorectal carcinomas and mesotheliomas do not stain with
this antibody. Lung adenocarcinoma rarely stains with this
antibody.
GCP-2 (granulocyte chemotactic protein-2)
Granulocyte chemotactic protein-2 is a chemokine of the
α (CXC) family. Osteosarcoma cells can produce both
human GCP-2 and interleukin-8 (IL8). The bovine homolog
of human CP-2 has been demonstrated in kidney tumor
cells. Human and bovine GCP-2 are chemotactic for human
granulocytes and activate postreceptor mechanisms that
cause the release of gelatinase B, which portends a possible
role in inflammation and tumor cell invasion. Tissue
sources include osteosarcoma cells and kidney neoplastic
cells. Granulocytes are the target cells.
G-CSF
Granulocyte colony-stimulating factor. A biological
response modifier that facilitates formation of granulocytes
in the bone marrow. It was first licensed by the U.S.
Food and Drug Administration in 1991 and may be useful
to reactivate granulocyte production in the marrow of
irradiated or chemotherapy-treated patients. The genes for
G-CSF are found on chromosome 17. Endothelial cells,
macrophages, and fibroblasts produce G-CSF, which functions
synergistically with IL3 in stimulating bone marrow
cells. G-CSF induces differentiation and clonal extinction
in certain myeloid leukemia cell lines. It promotes almost
exclusively the development of neutrophils from normal
hematopoietic progenitor cells.
GEF
Refer to guanine-nucleotide exchange factor.
gel
A semisolid substance prepared from seaweed agar that was
widely used in bacteriology and is now used in immunology
for diffusion of antigen and antibody in Ouchterlony-type
techniques, electrophoresis, immunoelectrophoresis, and
related methods.
gel diffusion
A method to evaluate antibodies and antigens based upon
their diffusion in gels toward one another and their reaction
at the point of contact in the gel.
gel filtration chromatography
This method permits the separation of molecules on the
basis of size. Porous beads are allowed to swell in buffer,
water, or other solutions and are packed into a column. The
molecular pores of the beads permit the entry of some molecules
and exclude others on the basis of size. Molecules
larger than the pores pass through the column and emerge
with the void volume. Because the solute molecules within
the beads maintain a concentration equilibrium with solutes
in the liquid phase outside the beads, molecular species
of a given weight, shape, and degree of hydration move as
a band. Gel chromatography using spherical agarose gel
particles is useful in the exclusion of immunoglobulin M
(IgM), which is present in the first peak. Of course, other
molecules of similar size, such as macroglobulins, are also
present in this peak. IgG is present in the second peak, but
the fractions of the leading side are contaminated by IgA
and IgD.
gemtuzumab
A humanized IgG4 monoclonal antibody that contains a
κ light chain specific for CD33, a sialoadhesion protein
G